Science.gov

Sample records for active force development

  1. Developing a musculoskeletal model of the primate skull: predicting muscle activations, bite force, and joint reaction forces using multibody dynamics analysis and advanced optimisation methods.

    PubMed

    Shi, Junfen; Curtis, Neil; Fitton, Laura C; O'Higgins, Paul; Fagan, Michael J

    2012-10-07

    An accurate, dynamic, functional model of the skull that can be used to predict muscle forces, bite forces, and joint reaction forces would have many uses across a broad range of disciplines. One major issue however with musculoskeletal analyses is that of muscle activation pattern indeterminacy. A very large number of possible muscle force combinations will satisfy a particular functional task. This makes predicting physiological muscle recruitment patterns difficult. Here we describe in detail the process of development of a complex multibody computer model of a primate skull (Macaca fascicularis), that aims to predict muscle recruitment patterns during biting. Using optimisation criteria based on minimisation of muscle stress we predict working to balancing side muscle force ratios, peak bite forces, and joint reaction forces during unilateral biting. Validation of such models is problematic; however we have shown comparable working to balancing muscle activity and TMJ reaction ratios during biting to those observed in vivo and that peak predicted bite forces compare well to published experimental data. To our knowledge the complexity of the musculoskeletal model is greater than any previously reported for a primate. This complexity, when compared to more simple representations provides more nuanced insights into the functioning of masticatory muscles. Thus, we have shown muscle activity to vary throughout individual muscle groups, which enables them to function optimally during specific masticatory tasks. This model will be utilised in future studies into the functioning of the masticatory apparatus.

  2. The development and validation of equations to predict grip force in the workplace: contributions of muscle activity and posture.

    PubMed

    Keir, Peter J; Mogk, Jeremy P M

    2005-08-15

    The inherent difficulty of measuring forces on the hand in ergonomic workplace assessments has led to the need for equations to predict grip force. A family of equations was developed, and validated, for the prediction of grip force using forearm electromyography (six finger and wrist muscles) as well as posture of the wrist (flexed, neutral and extended) and forearm (pronated, neutral, supinated). Inclusion of muscle activity was necessary to explain over 85% of the grip force variance and was further improved with wrist posture but not forearm posture. Posture itself had little predictive power without muscle activity (<1%). Nominal wrist posture improved predictive power more than the measured wrist angle. Inclusion of baseline muscle activity, the activity required to simply hold the grip dynamometer, greatly improved grip force predictions, especially at low force levels. While the complete model using six muscles and posture was the most accurate, the detailed validation and error analysis revealed that equations based on fewer components often resulted in a negligible reduction in predictive strength. Error was typically less than 10% under 50% of maximal grip force and around 15% over 50% of maximal grip force. This study presents detailed error analyses to both improve upon previous studies and to allow an educated decision to be made on which muscles to monitor depending on expected force levels, costs and error deemed acceptable by the potential user.

  3. The acute effects of static stretching on peak force, peak rate of force development and muscle activity during single- and multiple-joint actions in older women.

    PubMed

    Gonçalves, Raquel; Gurjão, André Luiz Demantova; Jambassi Filho, José Claudio; Farinatti, Paulo De Tarso Veras; Gobbi, Lilian Teresa Bucken; Gobbi, Sebastião

    2013-01-01

    The present study investigated the acute effects of static stretching on peak force, peak rate of force development and integrated electromyography (iEMG) in 27 older women (65 ± 4 years; 69 ± 9 kg; 157 ± 1 cm; 28 ± 4 kg · m(-2)). The participants were tested during two exercises (leg press and knee extension) after two conditions: stretching and control. The data were collected on four days (counterbalanced with a 24-hour rest period). In the stretching condition, the quadriceps muscle was stretched (knee flexion) for three sets of 30 s with 30 s rest intervals. No significant difference was detected for peak force and peak rate of force development during the single- and multiple-joint exercises, regardless of the following interactions: condition (stretching and control) vs. time (pre x post x 10 x 20 x 30 minutes post; P > 0.05) and exercise vs. time (P > 0.05). Additionally, no significant interaction was found for the iEMG activity (condition vs. time; P > 0.05) in the single- and multiple-joint exercises. In conclusion, a small amount of stretching of an agonist muscle (quadriceps) did not affect the peak force, peak rate of force development and EMG activity in older women during single- and multiple-joint exercises.

  4. Research, test, and development activities performed by junction box bypass diode task force # 4

    NASA Astrophysics Data System (ADS)

    Gade, Vivek; Shiradkar, Narendra; Robusto, Paul; Whitfield, Kent; Wohlgemuth, John; Uchida, Yasunori; Dhere, Neelkanth G.

    2014-10-01

    The paper provides latest update on the activities performed by the group #4-diodes, shading and reverse bias of the PV Module Quality Assurance Task Force (PVQAT) in the areas such as electrostatic discharge testing and standards, thermal runaway testing, diode junction temperature measurement techniques, thermal endurance tests and analysis of field failures. Philosophy, motivation and future direction for the group #4 is also discussed.

  5. Development of the method of an electrohydrodynamic force effect on a boundary layer for active control of aerodynamic flows

    NASA Astrophysics Data System (ADS)

    Aleshin, B. S.; Khomich, V. Yu.; Chernyshev, S. L.

    2016-12-01

    The results of investigations on the possibility of an electrohydrodynamic force effect on a gas flow implemented with the help of a barrier discharge are presented. A new method of controlling the laminar flow around a base with suppression of instabilities of the incoming flow due to electrohydrodynamic force action on the boundary layer near the forward edge of a swept wing is proposed. An efficient multidischarge actuator system is developed and created for active control of aerodynamic flows with induced-air-flow characteristics exceeding the world analogues.

  6. Haptic device development based on electro static force of cellulose electro active paper

    NASA Astrophysics Data System (ADS)

    Yun, Gyu-young; Kim, Sang-Youn; Jang, Sang-Dong; Kim, Dong-Gu; Kim, Jaehwan

    2011-04-01

    Haptic is one of well-considered device which is suitable for demanding virtual reality applications such as medical equipment, mobile devices, the online marketing and so on. Nowadays, many of concepts for haptic devices have been suggested to meet the demand of industries. Cellulose has received much attention as an emerging smart material, named as electro-active paper (EAPap). The EAPap is attractive for mobile haptic devices due to its unique characteristics in terms of low actuation power, suitability for thin devices and transparency. In this paper, we suggest a new concept of haptic actuator with the use of cellulose EAPap. Its performance is evaluated depending on various actuation conditions. As a result, cellulose electrostatic force actuator shows a large output displacement and fast response, which is suitable for mobile haptic devices.

  7. High-Reynolds Number Active Blowing Semi-Span Force Measurement System Development

    NASA Technical Reports Server (NTRS)

    Lynn, Keith C.; Rhew, Ray D.; Acheson, Michael J.; Jones, Gregory S.; Milholen, William E.; Goodliff, Scott L.

    2012-01-01

    Recent wind-tunnel tests at the NASA Langley Research Center National Transonic Facility utilized high-pressure bellows to route air to the model for evaluating aircraft circulation control. The introduction of these bellows within the Sidewall Model Support System significantly impacted the performance of the external sidewall mounted semi-span balance. As a result of this impact on the semi-span balance measurement performance, it became apparent that a new capability needed to be built into the National Transonic Facility s infrastructure to allow for performing pressure tare calibrations on the balance in order to properly characterize its performance under the influence of static bellows pressure tare loads and bellows thermal effects. The objective of this study was to design both mechanical calibration hardware and an experimental calibration design that can be employed at the facility in order to efficiently and precisely perform the necessary loadings in order to characterize the semi-span balance under the influence of multiple calibration factors (balance forces/moments and bellows pressure/temperature). Using statistical design of experiments, an experimental design was developed allowing for strategically characterizing the behavior of the semi-span balance for use in circulation control and propulsion-type flow control testing at the National Transonic Facility.

  8. ForC lacks canonical formin activity but bundles actin filaments and is required for multicellular development of Dictyostelium cells.

    PubMed

    Junemann, Alexander; Winterhoff, Moritz; Nordholz, Benjamin; Rottner, Klemens; Eichinger, Ludwig; Gräf, Ralph; Faix, Jan

    2013-01-01

    Diaphanous-related formins (DRFs) drive the nucleation and elongation of linear actin filaments downstream of Rho GTPase signalling pathways. Dictyostelium formin C (ForC) resembles a DRF, except that it lacks a genuine formin homology domain 1 (FH1), raising the questions whether or not ForC can nucleate and elongate actin filaments. We found that a recombinant ForC-FH2 fragment does not nucleate actin polymerization, but moderately decreases the rate of spontaneous actin assembly and disassembly, although the barbed-end elongation rate in the presence of the formin was not markedly changed. However, the protein bound to and crosslinked actin filaments into loose bundles of mixed polarity. Furthermore, ForC is an important regulator of morphogenesis since ForC-null cells are severely impaired in development resulting in the formation of aberrant fruiting bodies. Immunoblotting revealed that ForC is absent during growth, but becomes detectable at the onset of early aggregation when cells chemotactically stream together to form a multicellular organism, and peaks around the culmination stage. Fluorescence microscopy of cells ectopically expressing a GFP-tagged, N-terminal ForC fragment showed its prominent accumulation in the leading edge, suggesting that ForC may play a role in cell migration. In agreement with its expression profile, no defects were observed in random migration of vegetative mutant cells. Notably, chemotaxis of starved cells towards a source of cAMP was severely impaired as opposed to control. This was, however, largely due to a marked developmental delay of the mutant, as evidenced by the expression profile of the early developmental marker csA. In line with this, chemotaxis was almost restored to wild type levels after prolonged starvation. Finally, we observed a complete failure of phototaxis due to abolished slug formation and a massive reduction of spores consistent with forC promoter-driven expression of β-galactosidase in prespore cells

  9. “Astronomy for a Better World”: IAU/OAD Task Force One Activities to Develop Astronomy Education and Research at Universities in the Developing World

    NASA Astrophysics Data System (ADS)

    Guinan, Edward Francis; Kolenberg, Katrien

    2015-08-01

    The Task Force (1) on Astronomy for Universities & Research (TF-1) was established in 2012 as part of the IAU Office of Astronomy for Development (OAD). This Task Force drives activities related to astronomy education and research at universities mainly in the developing world. Astronomy is used to stimulate research and education in STEM fields and to develop and promote astronomy in regions of the world where there is little or no astronomy. There is also potential for developing research in the historical and cultural aspects of astronomy which may prove important for stimulating an interest in the subject in communities where there is yet no established interest in the science.Since the establishment of the OAD, over 25 TF-1 programs have been funded (or partially funded) to support a wide variety of interesting and innovative astronomy programs in Africa, Asia, South-East Asia, Middle-East, and in South & Central America. Nearly every aspect of development has been supported. These programs include supporting: regional astronomy training schools, specialized workshops, research visits, university twinning programs, distance learning projects, university astronomy curriculum development, as well as small telescope and equipment grants. In addition, a large new program - Astrolab - was introduced (by J-P De Greve and Michele Gerbaldi) to bring starlight” into the class room. In the Astrolab program students carry out and reduce CCD photometry secured by them using remotely controlled telescopes. Results from pilot programs will be discussed.OAD TF-1 programs will be discussed along with future plans for improving and expanding these programs to bring astronomy education and research to a greater number of people and indeed to use Astronomy for a Better World. Information and advice will also be provided about applying for support in the future.

  10. 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

  11. Zero side force volute development

    NASA Technical Reports Server (NTRS)

    Anderson, P. G.; Franz, R. J.; Farmer, R. C.; Chen, Y. S.

    1995-01-01

    Collector scrolls on high performance centrifugal pumps are currently designed with methods which are based on very approximate flowfield models. Such design practices result in some volute configurations causing excessive side loads even at design flowrates. The purpose of this study was to develop and verify computational design tools which may be used to optimize volute configurations with respect to avoiding excessive loads on the bearings. The new design methodology consisted of a volute grid generation module and a computational fluid dynamics (CFD) module to describe the volute geometry and predict the radial forces for a given flow condition, respectively. Initially, the CFD module was used to predict the impeller and the volute flowfields simultaneously; however, the required computation time was found to be excessive for parametric design studies. A second computational procedure was developed which utilized an analytical impeller flowfield model and an ordinary differential equation to describe the impeller/volute coupling obtained from the literature, Adkins & Brennen (1988). The second procedure resulted in 20 to 30 fold increase in computational speed for an analysis. The volute design analysis was validated by postulating a volute geometry, constructing a volute to this configuration, and measuring the steady radial forces over a range of flow coefficients. Excellent agreement between model predictions and observed pump operation prove the computational impeller/volute pump model to be a valuable design tool. Further applications are recommended to fully establish the benefits of this new methodology.

  12. Bouncing on Mars and the Moon-the role of gravity on neuromuscular control: correlation of muscle activity and rate of force development.

    PubMed

    Ritzmann, Ramona; Freyler, Kathrin; Krause, Anne; Gollhofer, Albert

    2016-11-01

    On our astronomical neighbors Mars and the Moon, bouncing movements are the preferred locomotor techniques. During bouncing, the stretch-shortening cycle describes the muscular activation pattern. This study aimed to identify gravity-dependent changes in kinematic and neuromuscular characteristics in the stretch-shortening cycle. Hence, neuromuscular control of limb muscles as well as correlations between the muscles' pre-activation, reflex components, and force output were assessed in lunar, Martian, and Earth gravity. During parabolic flights, peak force (Fmax), ground-contact-time, rate of force development (RFD), height, and impulse were measured. Electromyographic (EMG) activities in the m. soleus (SOL) and gastrocnemius medialis (GM) were assessed before (PRE) and during bounces for the reflex phases short-, medium-, and long-latency response (SLR, MLR, LLR). With gradually decreasing gravitation, Fmax, RFD, and impulse were reduced, whereas ground-contact time and height increased. Concomitantly, EMG_GM decreased for PRE, SLR, MLR, and LLR, and in EMG_SOL in SLR, MLR, and LLR. For SLR and MLR, Fmax and RFD were positively correlated to EMG_SOL. For PRE and LLR, RFD and Fmax were positively correlated to EMG_GM. Findings emphasize that biomechanically relevant kinematic adaptations in response to gravity variation were accompanied by muscle- and phase-specific modulations in neural control. Gravitational variation is anticipated and compensated for by gravity-adjusted muscle activities. Importantly, the pre-activation and reflex phases were differently affected: in SLR and MLR, SOL is assumed to contribute to the decline in force output with a decreasing load, and, complementary in PRE and LLR, GM seems to be of major importance for force generation.

  13. Magnetic Resonance Force Microscope Development

    SciTech Connect

    Hammel, P.C.; Zhang, Z.; Suh, B.J.; Roukes, M.L.; Midzor, M.; Wigen, P.E.; Childress, J.R.

    1999-06-03

    Our objectives were to develop the Magnetic Resonance Force Microscope (MRFM) into an instrument capable of scientific studies of buried structures in technologically and scientifically important electronic materials such as magnetic multilayer materials. This work resulted in the successful demonstration of MRFM-detected ferromagnetic resonance (FMR) as a microscopic characterization tool for thin magnetic films. Strong FMR spectra obtained from microscopic Co thin films (500 and 1000 angstroms thick and 40 x 200 microns in lateral extent) allowed us to observe variations in sample inhomogeneity and magnetic anisotropy field. We demonstrated lateral imaging in microscopic FMR for the first time using a novel approach employing a spatially selective local field generated by a small magnetically polarized spherical crystallite of yttrium iron garnet. These successful applications of the MRFM in materials studies provided the basis for our successful proposal to DOE/BES to employ the MRF M in studies of buried interfaces in magnetic materials.

  14. T cell activation requires force generation

    PubMed Central

    Hu, Kenneth H.

    2016-01-01

    Triggering of the T cell receptor (TCR) integrates both binding kinetics and mechanical forces. To understand the contribution of the T cell cytoskeleton to these forces, we triggered T cells using a novel application of atomic force microscopy (AFM). We presented antigenic stimulation using the AFM cantilever while simultaneously imaging with optical microscopy and measuring forces on the cantilever. T cells respond forcefully to antigen after calcium flux. All forces and calcium responses were abrogated upon treatment with an F-actin inhibitor. When we emulated the forces of the T cell using the AFM cantilever, even these actin-inhibited T cells became activated. Purely mechanical stimulation was not sufficient; the exogenous forces had to couple through the TCR. These studies suggest a mechanical–chemical feedback loop in which TCR-triggered T cells generate forceful contacts with antigen-presenting cells to improve access to antigen. PMID:27241914

  15. Establishing a Communications Officer Force Development Program

    DTIC Science & Technology

    2006-06-01

    provide you an Air Force Force Development overview and intent in section 2. Section 2 is designed to set the perspective for section 3, which goes in...increased skill sets . [14] The Air Force has the force development doctrine and a flight plan that clearly draws an intent or thrust behind...Link without reading the phrase, “Fly, Fight, and Win in Air, Space, and Cyberspace.” To accomplish this bold vision, leadership has to set a course

  16. Mechanobiocatalysis: Modulating Enzymatic Activity with Mechanical Force

    DTIC Science & Technology

    2015-09-28

    displayed by enzymes and other materials. It was demonstrated that the application of forces to enzymes properly outfitted with polymers resulted in...intrinsic activities displayed by enzymes and other materials. It was demonstrated that the application of forces to enzymes properly outfitted with polymers ...of eYFP-containing polymer composites via the application of mechanical force, as well as showing that the photophysical properties displayed by

  17. The Impact of Environment and Occupation on the Health and Safety of Active Duty Air Force Members - Database Development

    DTIC Science & Technology

    2014-04-01

    abuse, and physical altercations), high-risk sexual behavior (e.g., unprotected sexual intercourse), and physical health issues, such as high blood... sexual activity questions (section 12- reproductive ) PHA Sexually transmitted disease Sponsor ID (SSN), dependent status, DOB, sponsor pay grade...based on encounters and responses. The requested Health Assessment data consisted of specific information relating to tobacco, alcohol, and sexual

  18. Structural changes in the myosin filament and cross-bridges during active force development in single intact frog muscle fibres: stiffness and X-ray diffraction measurements.

    PubMed

    Brunello, E; Bianco, P; Piazzesi, G; Linari, M; Reconditi, M; Panine, P; Narayanan, T; Helsby, W I; Irving, M; Lombardi, V

    2006-12-15

    Structural and mechanical changes occurring in the myosin filament and myosin head domains during the development of the isometric tetanus have been investigated in intact frog muscle fibres at 4 degrees C and 2.15 microm sarcomere length, using sarcomere level mechanics and X-ray diffraction at beamline ID2 of the European Synchrotron Radiation Facility (Grenoble, France). The time courses of changes in both the M3 and M6 myosin-based reflections were recorded with 5 ms frames using the gas-filled RAPID detector (MicroGap Technology). Following the end of the latent period (11 ms after the start of stimulation), force increases to the tetanus plateau value (T(0)) with a half-time of 40 ms, and the spacings of the M3 and M6 reflections (S(M3) and S(M6)) increase by 1.5% from their resting values, with time courses that lead that of force by approximately 10 and approximately 20 ms, respectively. These temporal relations are maintained when the increase of force is delayed by approximately 10 ms by imposing, from 5 ms after the first stimulus, 50 nm (half-sarcomere)(-1) shortening at the velocity (V(0)) that maintains zero force. Shortening at V(0) transiently reduces S(M3) following the latent period and delays the subsequent increase in S(M3), but only delays the S(M6) increase without a transient decrease. Shortening at V(0) imposed at the tetanus plateau causes an abrupt reduction of the intensity of the M3 reflection (I(M3)), whereas the intensity of the M6 reflection (I(M6)) is only slightly reduced. The changes in half-sarcomere stiffness indicate that the isometric force at each time point is proportional to the number of myosin heads bound to actin. The different sensitivities of the intensity and spacing of the M3 and M6 reflections to the mechanical responses support the view that the M3 reflection in active muscle originates mainly from the myosin heads attached to the actin filament and the M6 reflection originates mainly from a fixed structure in the

  19. Force Field Development for Lipid Membrane Simulations.

    PubMed

    Lyubartsev, Alexander P; Rabinovich, Alexander L

    2016-10-01

    With the rapid development of computer power and wide availability of modelling software computer simulations of realistic models of lipid membranes, including their interactions with various molecular species, polypeptides and membrane proteins have become feasible for many research groups. The crucial issue of the reliability of such simulations is the quality of the force field, and many efforts, especially in the latest several years, have been devoted to parametrization and optimization of the force fields for biomembrane modelling. In this review, we give account of the recent development in this area, covering different classes of force fields, principles of the force field parametrization, comparison of the force fields, and their experimental validation. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.

  20. Mechanical forces in plant growth and development.

    PubMed

    Fisher, D D; Cyr, R J

    2000-06-01

    Plant cells perceive forces that arise from the environment and from the biophysics of plant growth. These forces provide meaningful cues that can affect the development of the plant. Seedlings of Arabidopsis thaliana were used to examine the cytoplasmic tensile character of cells that have been implicated in the gravitropic response. Laser-trapping technology revealed that the starch-containing statoliths of the central columella cells in root caps are held loosely within the cytoplasm. In contrast, the peripheral cells have starch granules that are relatively resistant to movement. The role of the actin cytoskeleton in affecting the tensile character of these cells is discussed. To explore the role that biophysical forces might play in generating developmental cues, we have developed an experimental model system in which protoplasts, embedded in a synthetic agarose matrix, are subjected to stretching or compression. We have found that protoplasts subjected to these forces from five minutes to two hours will subsequently elongate either at right angles or parallel to the tensive or compressive force vector. Moreover, the cortical microtubules are found to be organized either at right angles or parallel to the tensive or compressive force vector. We discuss these results in terms of an interplay of information between the extracellular matrix and the underlying cytoskeleton.

  1. Mechanical forces in plant growth and development

    NASA Technical Reports Server (NTRS)

    Fisher, D. D.; Cyr, R. J.

    2000-01-01

    Plant cells perceive forces that arise from the environment and from the biophysics of plant growth. These forces provide meaningful cues that can affect the development of the plant. Seedlings of Arabidopsis thaliana were used to examine the cytoplasmic tensile character of cells that have been implicated in the gravitropic response. Laser-trapping technology revealed that the starch-containing statoliths of the central columella cells in root caps are held loosely within the cytoplasm. In contrast, the peripheral cells have starch granules that are relatively resistant to movement. The role of the actin cytoskeleton in affecting the tensile character of these cells is discussed. To explore the role that biophysical forces might play in generating developmental cues, we have developed an experimental model system in which protoplasts, embedded in a synthetic agarose matrix, are subjected to stretching or compression. We have found that protoplasts subjected to these forces from five minutes to two hours will subsequently elongate either at right angles or parallel to the tensive or compressive force vector. Moreover, the cortical microtubules are found to be organized either at right angles or parallel to the tensive or compressive force vector. We discuss these results in terms of an interplay of information between the extracellular matrix and the underlying cytoskeleton.

  2. Air Force cryocooler development for spacecraft

    NASA Technical Reports Server (NTRS)

    Haskin, William L.

    1987-01-01

    An overview is given of Air Force sponsored cryocooler development for long duration spacecraft missions. Alternate approaches are being pursued to insure eventual success. The types of closed cycle cryocoolers that are now in advanced development include Vuilleumier, turbo-Brayton, and rotary-reciprocating refrigerators. Linear Stirling coolers with magnetic bearings have also been jointly sponsored by NASA and the Air Force. Technology is also being explored for future coolers using magnetic materials at low temperatures and for refrigerators with sorption compresssors. All of these cryocoolers are presently configured primarily for use with infrared sensor systems, but the designs could be adapted for use with cryogenic fluid storage systems or other applications.

  3. Effect of Lateral Epicondylosis on Grip Force Development

    PubMed Central

    Chourasia, Amrish O.; Buhr, Kevin A.; Rabago, David P.; Kijowski, Richard; Irwin, Curtis B.; Sesto, Mary E.

    2012-01-01

    Introduction While it is well known that grip strength is adversely affected by lateral epicondylosis (LE), the effect of LE on rapid grip force generation is unclear. Purpose The purpose of this study was to evaluate the effect of LE on the ability to rapidly generate grip force. Methods Twenty-eight participants with LE (13 unilateral and 15 bilateral LE) and 13 healthy controls participated in this study. A Multi-Axis Profile dynamometer was used to evaluate grip strength and rapid grip force generation. The ability to rapidly produce force is comprised of the electromechanical delay and rate of force development. Electromechanical delay is defined as the time between the onset of electrical activity and the onset of muscle force production. The Patient Rated Tennis Elbow Evaluation (PRTEE) questionnaire was used to assess pain and functional disability. Magnetic resonance imaging was used to evaluate tendon degeneration. Results LE-injured upper extremities had lower rate of force development (−50 lbs/sec, CI [−17, −84]) and less grip strength (−7.8 lbs, CI [−3.3, −12.4]) than non-injured extremities. Participants in the LE group had a longer electromechanical delay (+59%, CI [29,97]) than controls. Peak rate of force development had a higher correlation (r=0.56)(p<0.05) with PRTEE function than grip strength (r=0.47) (p<0.05) and electromechanical delay (r=0.30)(p>0.05) for participants with LE. Conclusion In addition to a reduction in grip strength, those with LE had a reduction in rate of force development and an increase in electromechanical delay. Collectively, these changes may contribute to an increase in reaction time, which may affect risk for recurrent symptoms. These findings suggest that therapists may need to address both strength and rapid force development deficits in patients with LE. PMID:22137195

  4. Development of a microlateral force sensor and its evaluation using lateral force microscopy.

    PubMed

    Ando, Yasuhisa; Shiraishi, Naoki

    2007-03-01

    A microlateral force sensor (MLFS) was developed and evaluated using atomic force microscopy (AFM). The sensor was attached to a sensing table supported by a suspension system. The lateral motion of the sensing table was activated by a comb actuator. The driving voltage to the comb actuator was controlled to maintain a constant position of the sensing table by detecting the tunneling current at a detector, which consisted of two electrodes where the bias voltage was applied. An AFM was used to apply a lateral force to the sensing table of the sensor. When the probe of a cantilever was pressed against the sensing table and a raster scanning was conducted, the driving voltage of the comb actuator changed to compensate the friction force between the probe and sensing table. AFM measurements of an asperity array on the sensing table were conducted, and a lateral force microscopy image (LFM) was obtained from the change in driving voltage. The image by MLFS was very similar to the LFM image that was conventionally obtained from torsion of the cantilever. The LFM image strongly correlated with the gradient image calculated from the AFM topographic image. The force sensitivity of the MLFS was determined by comparing the LFM image obtained by using the MLFS with the tangential force derived from the gradient of the AFM image.

  5. Rotordynamic Forces Developed by Labyrinth Seals

    DTIC Science & Technology

    1984-11-01

    force coefficient model was also developed. Predictions obtain from the approximate model are much more sensitive to shaft speed than corresponding...configuration with fluid prerotation in the direction of shaft rotation. The independent variable is running speed and families of curves are...tooth radial clearance a-0.216 mm. and radial distance from cavity base to stator wall d-1,105 mm, The shaft speed flm33.410 rpm. the mean cavity

  6. Wheel Force Transducer Research and Development

    DTIC Science & Technology

    2012-03-02

    develop, validate and calibrate cost effective field test equipment for measuring tire characteristics on vehicles whilst driving off-road. The proposed... field test equipment for measuring tire characteristics on vehicles whilst driving off-road. The proposed wheel force transducer is an important...of simulating off-road terrain under laboratory conditions, field test equipment, that can determine tire characteristics on vehicles whilst driving

  7. Development of force adaptation during childhood.

    PubMed

    Konczak, Jürgen; Jansen-Osmann, Petra; Kalveram, Karl-Theodor

    2003-03-01

    Humans learn to make reaching movements in novel dynamic environments by acquiring an internal motor model of their limb dynamics. Here, the authors investigated how 4- to 11-year-old children (N = 39) and adults (N = 7) adapted to changes in arm dynamics, and they examined whether those data support the view that the human brain acquires inverse dynamics models (IDM) during development. While external damping forces were applied, the children learned to perform goal-directed forearm flexion movements. After changes in damping, all children showed kinematic aftereffects indicative of a neural controller that still attempted to compensate the no longer existing damping force. With increasing age, the number of trials toward complete adaptation decreased. When damping was present, forearm paths were most perturbed and most variable in the youngest children but were improved in the older children. The findings indicate that the neural representations of limb dynamics are less precise in children and less stable in time than those of adults. Such controller instability might be a primary cause of the high kinematic variability observed in many motor tasks during childhood. Finally, the young children were not able to update those models at the same rate as the older children, who, in turn, adapted more slowly than adults. In conclusion, the ability to adapt to unknown forces is a developmental achievement. The present results are consistent with the view that the acquisition and modification of internal models of the limb dynamics form the basis of that adaptive process.

  8. Shaping tissues by balancing active forces and geometric constraints

    NASA Astrophysics Data System (ADS)

    Foolen, Jasper; Yamashita, Tadahiro; Kollmannsberger, Philip

    2016-02-01

    The self-organization of cells into complex tissues during growth and regeneration is a combination of physical-mechanical events and biochemical signal processing. Cells actively generate forces at all stages in this process, and according to the laws of mechanics, these forces result in stress fields defined by the geometric boundary conditions of the cell and tissue. The unique ability of cells to translate such force patterns into biochemical information and vice versa sets biological tissues apart from any other material. In this topical review, we summarize the current knowledge and open questions of how forces and geometry act together on scales from the single cell to tissues and organisms, and how their interaction determines biological shape and structure. Starting with a planar surface as the simplest type of geometric constraint, we review literature on how forces during cell spreading and adhesion together with geometric constraints impact cell shape, stress patterns, and the resulting biological response. We then move on to include cell-cell interactions and the role of forces in monolayers and in collective cell migration, and introduce curvature at the transition from flat cell sheets to three-dimensional (3D) tissues. Fibrous 3D environments, as cells experience them in the body, introduce new mechanical boundary conditions and change cell behaviour compared to flat surfaces. Starting from early work on force transmission and collagen remodelling, we discuss recent discoveries on the interaction with geometric constraints and the resulting structure formation and network organization in 3D. Recent literature on two physiological scenarios—embryonic development and bone—is reviewed to demonstrate the role of the force-geometry balance in living organisms. Furthermore, the role of mechanics in pathological scenarios such as cancer is discussed. We conclude by highlighting common physical principles guiding cell mechanics, tissue patterning and

  9. [Genes, forces and forms: mechanical aspects of prenatal craniofacial development].

    PubMed

    Radlanski, Ralf J; Renz, Herbert

    2007-12-01

    Current knowledge of molecular signaling during craniofacial development is advancing rapidly. We know that cells can respond to mechanical stimuli by biochemical signaling. Thus, the link between mechanical stimuli and gene expression has become a new and important area of the morphological sciences. This field of research seems to be a revival of the old approach of developmental mechanics, which goes back to the embryologists His [36], Carey [13, 14], and Blechschmidt [5]. These researchers argued that forces play a fundamental role in tissue differentiation and morphogenesis. They understood morphogenesis as a closed system with living cells as the active part and biological, chemical, and physical laws as the rules. This review reports on linking mechanical aspects of developmental biology with the contemporary knowledge of tissue differentiation. We focus on the formation of cartilage (in relation to pressure), bone (in relation to shearing forces), and muscles (in relation to dilation forces). The cascade of molecules may be triggered by forces, which arise during physical cell and tissue interaction. Detailed morphological knowledge is mandatory to elucidate the exact location and timing of the regions where forces are exerted. Because this finding also holds true for the exact timing and location of signals, more 3D images of the developmental processes are required. Further research is also required to create methods for measuring forces within a tissue. The molecules whose presence and indispensability we are investigating appear to be mediators rather than creators of form.

  10. Genes, forces, and forms: mechanical aspects of prenatal craniofacial development.

    PubMed

    Radlanski, Ralf J; Renz, Herbert

    2006-05-01

    Current knowledge of molecular signaling during craniofacial development is advancing rapidly. We know that cells can respond to mechanical stimuli by biochemical signaling. Thus, the link between mechanical stimuli and gene expression has become a new and important area of the morphological sciences. This field of research seems to be a revival of the old approach of developmental mechanics, which goes back to the embryologists His (1874), Carey (1920), and Blechschmidt (1948). These researchers argued that forces play a fundamental role in tissue differentiation and morphogenesis. They understood morphogenesis as a closed system with living cells as the active part and biological, chemical, and physical laws as the rules. This review reports on linking mechanical aspects of developmental biology with the contemporary knowledge of tissue differentiation. We focus on the formation of cartilage (in relation to pressure), bone (in relation to shearing forces), and muscles (in relation to dilation forces). The cascade of molecules may be triggered by forces, which arise during physical cell and tissue interaction. Detailed morphological knowledge is mandatory to elucidate the exact location and timing of the regions where forces are exerted. Because this finding also holds true for the exact timing and location of signals, more 3D images of the developmental processes are required. Further research is also required to create methods for measuring forces within a tissue. The molecules whose presence and indispensability we are investigating appear to be mediators rather than creators of form.

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

    PubMed Central

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

    2015-01-01

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

  12. Population Growth, Energy Use, and Pollution: Understanding the Driving Forces of Global Change. Hands-On! Developing Active Learning Modules on the Human Dimensions of Global Change.

    ERIC Educational Resources Information Center

    Kuby, Michael

    Since the beginning of the scientific revolution in the 1700s, the absolute scale of the human economy has increased many times over, and, with it, the impact on the natural environment. This learning module's activities introduce the student to linkages among population growth, energy use, level of economic and technological development and their…

  13. Tool Forces Developed During Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Melendez, M.; Tang, W.; Schmidt, C.; McClure, J. C.; Nunes, A. C.; Murr, L. E.

    2003-01-01

    This paper will describe a technique for measuring the various forces and the torque that exist on the Friction Stir Welding pin tool. Results for various plunge depths, weld speeds, rotational speed, and tool configurations will be presented. Welds made on 6061 aluminum with typical welding conditions require a downward force of 2800 lbs. (12.5 kN) a longitudinal force in the direction of motion of 300 lbs (1.33 kN), a transverse force in the omega x v direction of 30 lbs (135 N). Aluminum 2195 under typical weld conditions requires a downward force of 3100 lbs. (1.38 kN), a longitudinal force of 920 lbs. (4.1 kN), and a transverse force of 45 lbs. (200 N) in the omega x v direction.

  14. The Impact of Environment and Occupation on the Health and Safety of Active Duty Air Force Members: Database Development and De-Identification.

    PubMed

    Erich, Roger; Eaton, Melinda; Mayes, Ryan; Pierce, Lamar; Knight, Andrew; Genovesi, Paul; Escobar, James; Mychalczuk, George; Selent, Monica

    2016-08-01

    Preparing data for medical research can be challenging, detail oriented, and time consuming. Transcription errors, missing or nonsensical data, and records not applicable to the study population may hamper progress and, if unaddressed, can lead to erroneous conclusions. In addition, study data may be housed in multiple disparate databases and complex formats. Merging methods may be incomplete to obtain temporally synchronized data elements. We created a comprehensive database to explore the general hypothesis that environmental and occupational factors influence health outcomes and risk-taking behavior among active duty Air Force personnel. Several databases containing demographics, medical records, health survey responses, and safety incident reports were cleaned, validated, and linked to form a comprehensive, relational database. The final step involved removing and transforming personally identifiable information to form a Health Insurance Portability and Accountability Act compliant limited database. Initial data consisted of over 62.8 million records containing 221 variables. When completed, approximately 23.9 million clean and valid records with 214 variables remained. With a clean, robust database, future analysis aims to identify high-risk career fields for targeted interventions or uncover potential protective factors in low-risk career fields.

  15. The effect of keyboard keyswitch make force on applied force and finger flexor muscle activity.

    PubMed

    Rempel, D; Serina, E; Klinenberg, E; Martin, B J; Armstrong, T J; Foulke, J A; Natarajan, S

    1997-08-01

    The design of the force-displacement characteristics or 'feel' of keyboard keyswitches has been guided by preference and performance data; there has been very little information on how switch 'feel' alters muscle activity or applied force. This is a laboratory-based repeated measures design experiment to evaluate the effect of computer keyboard keyswitch design on applied finger force and muscle activity during a typing task. Ten experienced typists typed on three keyboards which differed in keyswitch make force (0.34, 0.47 and 1.02 N) while applied fingertip force and finger flexor electromyograms were recorded. The keyboard testing order was randomized and subjects typed on each keyboard for three trials, while data was collected for a minimum of 80 keystrokes per trial. No differences in applied fingertip force or finger flexor EMG were observed during typing on keyboards with switch make force of 0.34 or 0.47 N. However, applied fingertip force increased by approximately 40% (p < 0.05) and EMG activity increased by approximately 20% (p < 0.05) when the keyswitch make force was increased from 0.47 to 1.02 N. These results suggest that, in order to minimize the biomechanical loads to forearm tendons and muscles of keyboard users, keyswitches with a make force of 0.47 N or less should be considered over switches with a make force of 1.02 N.

  16. Training Chrysalis: Applications of Special Forces Training in the Development of the Objective Force

    DTIC Science & Technology

    2006-05-31

    TRAINING CHRYSALIS: APPLICATIONS OF SPECIAL FORCES TRAINING IN THE DEVELOPMENT OF THE OBJECTIVE FORCE A thesis presented to the Faculty of the U.S...Coleman, B.A. Accepted this 6th day of June 2003 by: , Director, Graduate Degree...Force O & O Operational and Organizational Plan PCS Permanent Change of Station POI Program of Instruction vii SERE Survival, Evasion, Resistance, and

  17. Transient Casimir Forces from Quenches in Thermal and Active Matter.

    PubMed

    Rohwer, Christian M; Kardar, Mehran; Krüger, Matthias

    2017-01-06

    We compute fluctuation-induced (Casimir) forces for classical systems after a temperature quench. Using a generic coarse-grained model for fluctuations of a conserved density, we find that transient forces arise even if the initial and final states are force free. In setups reminiscent of Casimir (planar walls) and van der Waals (small inclusions) interactions, we find comparable exact universal expressions for the force. Dynamical details only scale the time axis of transient force curves. We propose that such quenches can be achieved, for instance, in experiments on active matter, employing tunable activity or interaction protocols.

  18. Transient Casimir Forces from Quenches in Thermal and Active Matter

    NASA Astrophysics Data System (ADS)

    Rohwer, Christian M.; Kardar, Mehran; Krüger, Matthias

    2017-01-01

    We compute fluctuation-induced (Casimir) forces for classical systems after a temperature quench. Using a generic coarse-grained model for fluctuations of a conserved density, we find that transient forces arise even if the initial and final states are force free. In setups reminiscent of Casimir (planar walls) and van der Waals (small inclusions) interactions, we find comparable exact universal expressions for the force. Dynamical details only scale the time axis of transient force curves. We propose that such quenches can be achieved, for instance, in experiments on active matter, employing tunable activity or interaction protocols.

  19. Advanced atomic force microscopy: Development and application

    NASA Astrophysics Data System (ADS)

    Walters, Deron A.

    Over the decade since atomic force microscopy (AFM) was invented, development of new microscopes has been closely intertwined with application of AFM to problems of interest in physics, chemistry, biology, and engineering. New techniques such as tapping mode AFM move quickly in our lab from the designer's bench to the user's table-since this is often the same piece of furniture. In return, designers get ample feedback as to what problems are limiting current instruments, and thus need most urgent attention. Tip sharpness and characterization are such a problem. Chapter 1 describes an AFM designed to operate in a scanning electron microscope, whose electron beam is used to deposit sharp carbonaceous tips. These tips can be tested and used in situ. Another limitation is addressed in Chapter 2: the difficulty of extracting more than just topographic information from a sample. A combined AFM/confocal optical microscope was built to provide simultaneous, independent images of the topography and fluorescence of a sample. In combination with staining or antibody labelling, this could provide submicron information about the composition of a sample. Chapters 3 and 4 discuss two generations of small cantilevers developed for lower-noise, higher-speed AFM of biological samples. In Chapter 4, a 26 mum cantilever is used to image the process of calcite growth from solution at a rate of 1.6 sec/frame. Finally, Chapter 5 explores in detail a biophysics problem that motivates us to develop fast, quiet, and gentle microscopes; namely, the control of crystal growth in seashells by the action of soluble proteins on a growing calcite surface.

  20. Nuclear forces from EFT: Recent developments

    NASA Astrophysics Data System (ADS)

    Krebs, H.; Epelbaum, E.; Meißner, U.-G.

    2010-04-01

    Nuclear forces are considered based on chiral perturbation theory with and without explicit ∆-isobar degrees of freedom. We discuss the subleading corrections to chiral three-nucleon forces in the ∆-less formalism which contain no additional free parameters. In the formalism with explicit ∆-isobar we present the complete next-to-next-to-leading order analysis of isospin-conserving and next-to-leading order analysis of isospinviolating nuclear forces. The perturbative expansion of nuclear forces in the ∆-full case is shown to have much better convergence compared with the ∆-less theory where the ∆-resonance is integrated out and is encoded in certain low-energy constants.

  1. Arch development with trans-force lingual appliances.

    PubMed

    Clark, William J

    2005-01-01

    Trans-Force lingual appliances are designed to correct arch form in patients with contracted dental arches. Interceptive treatment with this new series of pre-activated lingual appliances offers new possibilities for arch development, in combination with fixed appliances. Palatal and lingual appliances insert in horizontal lingual sheaths in molar bands. No activation is required after the appliance is fitted, and this principle is extended to a series of appliances for sagittal and transverse arch development. Both sagittal and transverse appliances have additional components to achieve 3-way expansion where this is indicated. The invisible lingual appliances may be used in correction of all classes of malocclusion at any stage of development, from mixed dentition through permanent dentition, and this approach has wide indications in adult treatment.

  2. Human force discrimination during active arm motion for force feedback design.

    PubMed

    Feyzabadi, Seyedshams; Straube, Sirko; Folgheraiter, Michele; Kirchner, Elsa Andrea; Kim, Su Kyoung; Albiez, Jan Christian

    2013-01-01

    The goal of this study was to analyze the human ability of external force discrimination while actively moving the arm. With the approach presented here, we give an overview for the whole arm of the just-noticeable differences (JNDs) for controlled movements separately executed for the wrist, elbow, and shoulder joints. The work was originally motivated in the design phase of the actuation system of a wearable exoskeleton, which is used in a teleoperation scenario where force feedback should be provided to the subject. The amount of this force feedback has to be calibrated according to the human force discrimination abilities. In the experiments presented here, 10 subjects performed a series of movements facing an opposing force from a commercial haptic interface. Force changes had to be detected in a two-alternative forced choice task. For each of the three joints tested, perceptual thresholds were measured as absolute thresholds (no reference force) and three JNDs corresponding to three reference forces chosen. For this, we used the outcome of the QUEST procedure after 70 trials. Using these four measurements we computed the Weber fraction. Our results demonstrate that different Weber fractions can be measured with respect to the joint. These were 0.11, 0.13, and 0.08 for wrist, elbow, and shoulder, respectively. It is discussed that force perception may be affected by the number of muscles involved and the reproducibility of the movement itself. The minimum perceivable force, on average, was 0.04 N for all three joints.

  3. Grip force and muscle activity differences due to glove type.

    PubMed

    Kovacs, Kimberly; Splittstoesser, Riley; Maronitis, Anthony; Marras, William S

    2002-01-01

    The purpose of this study was to investigate the effects of different types and sizes of gloves on external grip force and muscle activity. Twenty-one male and seven female volunteers served as subjects. Each subject performed two maximum voluntary grip contractions while wearing each of the 10 glove types. Results indicated significant differences in the effects of different glove types on the peak force, ratio of peak force to normalized flexor muscle EMG activity, and the ratio of peak force to coactivity.

  4. Observational assessment of forceful exertion and the perceived force demands of daily activities.

    PubMed

    Marshall, Matthew M; Armstrong, Thomas J

    2004-12-01

    The primary objective of this study was to assess the accuracy and precision with which analysts observe and estimate the force produced as subjects performed exertions on a work simulator. Eight analysts observed 32 subjects and estimated force as a percent of subjects' maximum voluntary contraction (% MVC). Analysts exhibited bias toward the mean, as high force exertions (> 67% MVC) were underestimated (mean: 11.6% MVC) and low force exertions (<34% MVC) were overestimated (mean: 6.7% MVC). Average error for medium force exertions (34-67% MVC) was not statistically different from zero (2.1% MVC). For all force levels, precision of the estimate was very poor (standard deviation range: 16.2-20.7% MVC). Experience of the analyst in performing ergonomic analysis did not affect accuracy. A secondary objective of the study was to conduct a survey in which subjects identified activities of daily living they perceived as equivalent to controlled force levels. A total of 59 different activities ranging from minimal force required to near maximum were listed by at least 5% of the participants. This list may be used to assist health care practitioners and patients convey the force demands required of occupational tasks as well as for evaluating the diminished strength of the patient.

  5. New developments advance forced-oxidation FGD

    SciTech Connect

    Ellison, W.; Kutemeyer, P.M.

    1983-02-01

    In the US, many utility companies are specifying forced oxidation to help to stabilize the sludge from wet-limestone scrubbers. This technique is already used in Japan and West Germany. The oxidized sludge can be more easily dewatered and thus requires considerably less disposal area than is needed for ponding the FGD sludge. The solids can also be upgraded to a commercial-grade gypsum. The processes required and the systems currently in use in Japan and West Germany are described.

  6. Canadian Forces Education as a Contributor to National Development.

    ERIC Educational Resources Information Center

    McRoberts, B. G.

    The education and training provided by the Canadian Armed Forces is analyzed in consideration of its contribution to both the economic and social aspects of national development. From this analysis it appears that the Armed Forces' extensive formally organized education and training program has an important impact on economic development when…

  7. Development of cylindrical-type finger force measuring system using force sensors and its characteristics evaluation

    NASA Astrophysics Data System (ADS)

    Kim, Hyeon-Min; Yoon, Joungwon; Shin, Hee-Suk; Kim, Gab-Soon

    2012-02-01

    Some patients cannot use their hands because of the paralysis of their fingers. Their fingers can recover with rehabilitative training, and the extent of rehabilitation can be judged by grasping a cylindrical-object with their fingers. At present, the cylindrical-object used in hospitals is only a plastic cylinder, which cannot measure grasping force of the fingers. Therefore, doctors must judge the extent of rehabilitation by watching patients' fingers as they grasp the plastic cylinder. In this paper, the development of two cylindrical-type finger force measuring systems with four force sensors for left hand and right hand were developed. The developed finger force measuring system can measure the grasping force of patients' each finger (forefinger, middle finger, ring finger and little finger), and the measured results could be used to judge the rehabilitation extent of a finger patient. The grasping force tests of men and women were performed using the developed cylindrical-type finger force measuring systems. The tests confirm that the average finger forces of right hand and left hand for men were about 194 N and 179 N, and for women, 108 N and 95 N.

  8. Force-activated reactivity switch in a bimolecular chemical reaction.

    PubMed

    Garcia-Manyes, Sergi; Liang, Jian; Szoszkiewicz, Robert; Kuo, Tzu-Ling; Fernández, Julio M

    2009-06-01

    The effect of mechanical force on the free-energy surface that governs a chemical reaction is largely unknown. The combination of protein engineering with single-molecule force-clamp spectroscopy allows us to study the influence of mechanical force on the rate at which a protein disulfide bond is reduced by nucleophiles in a bimolecular substitution reaction (S(N)2). We found that cleavage of a protein disulfide bond by hydroxide anions exhibits an abrupt reactivity 'switch' at ∼500 pN, after which the accelerating effect of force on the rate of an S(N)2 chemical reaction greatly diminishes. We propose that an abrupt force-induced conformational change of the protein disulfide bond shifts its ground state, drastically changing its reactivity in S(N)2 chemical reactions. Our experiments directly demonstrate the action of a force-activated switch in the chemical reactivity of a single molecule.

  9. International Reference Ionosphere (IRI): Task Force Activity 2000

    NASA Technical Reports Server (NTRS)

    Bilitza, D.

    2000-01-01

    The annual IRI Task Force Activity was held at the Abdus Salam International Center for Theoretical Physics in Trieste, Italy from July 10 to July 14. The participants included J. Adeniyi (University of Ilorin, Nigeria), D. Bilitza (NSSDC/RITSS, USA), D. Buresova (Institute of Atmospheric Physics, Czech Republic), B. Forte (ICTP, Italy), R. Leitinger (University of Graz, Austria), B. Nava (ICTP, Italy), M. Mosert (University National Tucuman, Argentina), S. Pulinets (IZMIRAN, Russia), S. Radicella (ICTP, Italy), and B. Reinisch (University of Mass. Lowell, USA). The main topic of this Task Force Activity was the modeling of the topside ionosphere and the development of strategies for modeling of ionospheric variability. Each day during the workshop week the team debated a specific modeling problem in the morning during informal presentations and round table discussions of all participants. Ways of resolving the specific modeling problem were devised and tested in the afternoon in front of the computers of the ICTP Aeronomy and Radiopropagation Laboratory using ICTP s computer networks and internet access.

  10. Infusing a Global Perspective into the Study of Agriculture: Student Activities. Volume 1. Developed by the National Task Force on International Agricultural Education.

    ERIC Educational Resources Information Center

    Martin, Robert A., Ed.

    The need to develop an awareness of the global nature of the agriculture industry is one of the major issues that students must begin to understand. A packet of instructional materials was developed to help teachers infuse a global perspective into units of instruction about agriculture and related topics. This document offers a series of…

  11. Analysis of sitting forces on stationary chairs for daily activities.

    PubMed

    Hu, Lingling; Tackett, Bob; Tor, Onder; Zhang, Jilei

    2016-04-01

    No literature related to the study of sitting forces on chairs sat on by people who weighed over 136 kg was found. The Business Institutional Furniture Manufactures Association needs force data for development of performance test standards to test chairs for users who weigh up to 181 kg. 20 participants who weighed from 136 to 186 kg completed 6 tasks on an instrumented chair in the sequence of sitting down, remaining seated and rising. Effects of sitting motion, armrest use and seat cushion thickness on vertical sitting forces and centre-of-force were investigated. Results indicated hard sitting down yielded the highest sitting force of 213% in terms of participants' body weights. Armrest use affected sitting forces of normal sitting down, but not of rising and hard sitting down. Cushion thickness affected sitting forces of normal and hard sitting down and shifting, but not of rising, static seating or stretching backward situations. Practitioner Summary: Results of the sitting force and centre-of-force data obtained for this research can help furniture manufacturers develop new product performance test standards for creating reliable engineering design and manufacturing quality and durable products to meet a niche market need.

  12. 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.

  13. FEMALE LABOR FORCE PARTICIPATION AND ECONOMIC DEVELOPMENT,

    DTIC Science & Technology

    result, the share of females and elderly persons in the working-age population has increased. For the periods 1900-1930 and 1930-1950, the relation...occupations and the characteristics of women as active workers. in section IV a procedure is adopted for testing the relation between the growth of the

  14. Leadership Development in the Civilian Work Force

    DTIC Science & Technology

    1984-05-17

    targeted for preparing future managers with the requisite leadership skills to succeed in the job. Although the corporations may use different...approaches to accomplish leadership development, each corporation has a lucid and systematic program for developing its leaders. In contrast, the Department...The company "cul- ture" at both corporations was distinctly different. The "culture" at Texas Instruments was decidedly "Texas" in its orientation. A

  15. Isometric squat force output and muscle activity in stable and unstable conditions.

    PubMed

    McBride, Jeffrey M; Cormie, Prue; Deane, Russell

    2006-11-01

    The purpose of this study was to assess the effect of stable vs. unstable conditions on force output and muscle activity during an isometric squat. Nine men involved in recreational resistance training participated in the investigation by completing a single testing session. Within this session subjects performed isometric squats either while standing directly on the force plate (stable condition, S) or while standing on inflatable balls placed on top of the force plate (unstable condition, U). Electromyography (EMG) was recorded during both conditions from the vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), and medial gastrocnemius (G) muscles. Results indicated peak force (PF) and rate of force development (RFD) were significantly lower, 45.6% and 40.5% respectively, in the U vs. S condition (p < or = 0.05). Average integrated EMG values for the VL and VM were significantly higher in the S vs. U condition. VL and VM muscle activity was 37.3% and 34.4% less in U in comparison to S. No significant differences were observed in muscle activity of the BF or G between U and S. The primary finding in this investigation is that isometric squatting in an unstable condition significantly reduces peak force, rate of force development, and agonist muscle activity with no change in antagonist or synergist muscle activity. In terms of providing a stimulus for strength gain no discernable benefit of performing a resistance exercise in an unstable condition was observed in the current study.

  16. The Development of French Nuclear Forces

    DTIC Science & Technology

    1987-11-01

    the following issues : 1) restoration of pre-war status 2) restoration of French confidence 3) past and present concerns about dependency on alliances...casual 4 observer to be a nation or fine wines, excellent cuisine , contemporary fashion, fine furniture, classic art, and a revolutionary heritage. But... issues like the development of nuclear weapons is best described by 7 Lawrence Scheinman in Atomic Energy Policy in France Under the Fourth Republic

  17. Development of a force specification for a force-limited random vibration test

    SciTech Connect

    Stevens, R.R.

    1996-02-01

    Vibration testing, techniques have been developed and employed that reduce the overtesting caused by the essentially infinite mechanical impedance of the shaker in conventional vibration tests. With these ``force-limiting`` techniques, two vibration test specifications are used: the conventional acceleration specification, and an interface force specification. The vibration level of the shake table is controlled such that neither the table acceleration nor the force transmitted to the test item exceeds its specification, hence the name ``dual control`` vibration test. The effect of limiting the shake table vibration to the force specification is to reduce (``notch``) the shaker acceleration near some of the test item`s resonance frequencies. Several methods of deriving the force specification have been described in the literature. A new method is proposed in this paper that is based on a modal method of coupling two dynamic systems, in this case the ``source`` or launch vehicle, and the ``load`` or payload. The only information that is required is an experimentally-measurable frequency-response function (FRF) called the dynamic mass for both the source and the load. The method, referred to as the coupled system, modal approach (CSMA) method, is summarized and compared to an existing method of determining the force specification for force-limited vibration testing.

  18. Mapping Muscles Activation to Force Perception during Unloading

    PubMed Central

    Toma, Simone; Lacquaniti, Francesco

    2016-01-01

    It has been largely proved that while judging a force humans mainly rely on the motor commands produced to interact with that force (i.e., sense of effort). Despite of a large bulk of previous investigations interested in understanding the contributions of the descending and ascending signals in force perception, very few attempts have been made to link a measure of neural output (i.e., EMG) to the psychophysical performance. Indeed, the amount of correlation between EMG activity and perceptual decisions can be interpreted as an estimate of the contribution of central signals involved in the sensation of force. In this study we investigated this correlation by measuring the muscular activity of eight arm muscles while participants performed a quasi-isometric force detection task. Here we showed a method to quantitatively describe muscular activity (“muscle-metric function”) that was directly comparable to the description of the participants' psychophysical decisions about the stimulus force. We observed that under our experimental conditions, muscle-metric absolute thresholds and the shape of the muscle-metric curves were closely related to those provided by the psychophysics. In fact a global measure of the muscles considered was able to predict approximately 60% of the perceptual decisions total variance. Moreover the inter-subjects differences in psychophysical sensitivity showed high correlation with both participants' muscles sensitivity and participants' joint torques. Overall, our findings gave insights into both the role played by the corticospinal motor commands while performing a force detection task and the influence of the gravitational muscular torque on the estimation of vertical forces. PMID:27032087

  19. A viable non-axisymmetric non-force-free field to represent solar active regions

    NASA Astrophysics Data System (ADS)

    Prasad, A.; Bhattacharyya, R.

    2016-11-01

    A combination of analytical calculations and vectormagnetogram data is utilized to develop a non-axisymmetric non-force-free magnetic field and assess its viability in describing solar active regions. For that purpose, we construct a local spherical shell where a planar surface, tangential to the inner sphere, represents a Cartesian cutout of an active region. The magnetic field defined on the surface is then correlated with magnetograms. The analysis finds that the non-axisymmetric non-force-free magnetic field, obtained by a superposition of two linear-force-free fields, correlates reasonably well with magnetograms.

  20. The Force on a Boundary in Active Matter

    NASA Astrophysics Data System (ADS)

    Brady, John; Yan, Wen

    2015-11-01

    We present a general theory for determining the force (and torque) exerted on a boundary (or body) in active matter. The theory extends the description of passive Brownian colloids to self-propelled active particles and applies for all ratios of the thermal energy kB T to the swimmer's activity ksTs = ζU02τR / 6 , where ζ is the Stokes drag coefficient, U0 is the swim speed and τR is the reorientation time of the active particles. The theory has a natural microscopic length scale over which concentration and orientation distributions are confined near boundaries, but the microscopic length does not appear in the force. The swim pressure emerges naturally and dominates the behavior when the boundary size is large compared to the swimmer's run length l =U0τR . The theory is used to predict the motion of bodies of all sizes immersed in active matter.

  1. Force.

    ERIC Educational Resources Information Center

    Gamble, Reed

    1989-01-01

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

  2. The relationship between force and focal complex development

    PubMed Central

    Galbraith, Catherine G.; Yamada, Kenneth M.; Sheetz, Michael P.

    2002-01-01

    To adhere and migrate, cells must be capable of applying cytoskeletal force to the extracellular matrix (ECM) through integrin receptors. However, it is unclear if connections between integrins and the ECM are immediately capable of transducing cytoskeletal contraction into migration force, or whether engagement of force transmission requires maturation of the adhesion. Here, we show that initial integrin–ECM adhesions become capable of exerting migration force with the recruitment of vinculin, a marker for focal complexes, which are precursors of focal adhesions. We are able to induce the development of focal complexes by the application of mechanical force to fibronectin receptors from inside or outside the cell, and we are able to extend focal complex formation to vitronectin receptors by the removal of c-Src. These results indicate that cells use mechanical force as a signal to strengthen initial integrin–ECM adhesions into focal complexes and regulate the amount of migration force applied to individual adhesions at localized regions of the advancing lamella. PMID:12446745

  3. Joint Concept Development and Experimentation: A Force Development Perspective

    DTIC Science & Technology

    2012-02-01

    Defence R& D Canada Centre for Operational Research and Analysis Warfare Centre Science Team Canadian Forces Warfare Centre Joint Concept...Warfare Centre Sciences Team Lead DRDC CORA Defence R& D Canada – CORA Technical Memorandum DRDC CORA TM 2012-036 February 2012...Scientist, DRDC CORA Defence R& D Canada – Centre for Operational Research and Analysis (CORA) © Her Majesty the Queen in Right of Canada, as

  4. Children's Spiritual Development in Forced Displacement: A Human Rights Perspective

    ERIC Educational Resources Information Center

    Ojalehto, Bethany; Wang, Qi

    2008-01-01

    This article provides a synthesis of current research and theories of spiritual development in forced displacement from a human rights perspective. Spirituality, understood as a cognitive-cultural construct, has shown positive impact on children's development through both collective and individual processes and across ecological domains of the…

  5. House Divided: The Splitting of Active Duty Civil Affairs Forces

    DTIC Science & Technology

    2009-12-01

    training of Active Duty Civil Affairs. This will allow the reader to become familiar with the Active branch as a whole and show the different...readers are extremely familiar with the large-scale environment given the nightly news coverage, but the small-scale environment is decidedly different...apparatus and are familiar with operating in conjunction with embassies and country teams. While conventional forces also have their own intelligence

  6. Proteolytic activity alterations resulting from force-feeding in Muscovy and Pekin ducks.

    PubMed

    Awde, S; Marty-Gasset, N; Wilkesman, J; Rémignon, H

    2013-11-01

    We investigated liver protease activity in force-fed and non-force-fed ducks using zymography gels to better understand mechanisms underlying liver steatosis in palmipeds. Male Muscovy and Pekin ducks were slaughtered before and after a short period (13 d) while they were conventionally fed or force fed. The force-fed regimen contained a high level of carbohydrates and was delivered in large doses. Main hepatic proteases (matrix metalloprotease-2, calpains, and cathepsins) were extracted from raw liver and specifically activated within electrophoretic gels. Both force-fed Muscovy and Pekin ducks presented higher liver weights and BW associated with lower matrix metalloprotease-2 and m-calpain hepatic activities. On the other hand, hepatic cathepsin activity was not affected by force feeding. It was concluded that Muscovy and Pekin duck hepatic proteases are affected similarly by the force feeding. Thus, this cannot explain differences observed between Muscovy and Pekin ducks regarding their ability to develop hepatic steatosis generally reported in literature.

  7. An Improved Force Feedback Control Algorithm for Active Tendons

    PubMed Central

    Guo, Tieneng; Liu, Zhifeng; Cai, Ligang

    2012-01-01

    An active tendon, consisting of a displacement actuator and a co-located force sensor, has been adopted by many studies to suppress the vibration of large space flexible structures. The damping, provided by the force feedback control algorithm in these studies, is small and can increase, especially for tendons with low axial stiffness. This study introduces an improved force feedback algorithm, which is based on the idea of velocity feedback. The algorithm provides a large damping ratio for space flexible structures and does not require a structure model. The effectiveness of the algorithm is demonstrated on a structure similar to JPL-MPI. The results show that large damping can be achieved for the vibration control of large space structures. PMID:23112660

  8. Mechanical forces in the development of leaf venation networks

    NASA Astrophysics Data System (ADS)

    Corson, Francis; Boudaoud, Arezki; Adda-Bedia, Mokhtar

    2008-03-01

    Leaf venation patterns, like leaf shapes, are extremely diverse, yet their local structure has been shown to satisfy a simple, universal property: the angles veins form at junctions are related to their diameters by a vectorial equation analogous to a force balance. This structure is the signature of a reorganization of vein networks during the development of leaves, a process we investigated numerically using a cell proliferation model. Provided that vein cells are given different mechanical properties, tensile forces develop along the veins during growth, causing the network to deform progressively. The statistics of the patterns obtained in these simulations are in good quantitative agreement with observations on leaves, supporting the notion that the local structure of leaf venation networks reflects a balance of mechanical forces.

  9. Psychosocial Aspects of Nuclear Developments. Task Force Report 20.

    ERIC Educational Resources Information Center

    American Psychiatric Association, Washington, DC.

    This is the report of a task force formed to bring psychological understanding to bear on the various aspects of the development of nuclear arms and nuclear energy and the threat they pose to human physical, mental, and emotional health. The first of seven articles considers the sociopsychological aspects of the nuclear arms race. Other articles…

  10. Spartanburg Technical College 1998 Work Force Development Survey.

    ERIC Educational Resources Information Center

    Quinley, John W.; Cantrell, Jo Ellen

    The 1998 Work Force Development Study focuses on Spartanburg Technical College's (STC's) (South Carolina) role in preparing new workers and training/retraining the current workforce. Surveys were mailed to employers in business and industry--the response rate was 10%. In addition, a series of focus groups, including various business, industry,…

  11. Canadian developments. Bill to export generic drugs comes into force.

    PubMed

    Garmaise, David

    2005-08-01

    The Jean Chrétien Pledge to Africa Act (the Act), the Canadian legislation aimed at allowing the export of lower-cost medicines to developing countries, came into force on 14 May 2005, exactly one year after it received Royal Assent.

  12. Developing and Assessing a Force and Motion Learning Progression

    ERIC Educational Resources Information Center

    Alonzo, Alicia C.; Steedle, Jeffrey T.

    2009-01-01

    Learning progressions are ordered descriptions of students' understanding of a given concept. In this paper, we describe the iterative process of developing a force and motion learning progression and associated assessment items. We report on a pair of studies designed to explore the diagnosis of students' learning progression levels. First, we…

  13. Air Force Officer Qualifying Test Form O: Development and Standardization.

    ERIC Educational Resources Information Center

    Rogers, Deborah L.; And Others

    This report presents the rationale, development, and standardization of the Air Force Officer Qualifying Test (AFOQT) Form O. The test is used to select individuals for officer commissioning programs, and candidates for pilot and navigator training. Form O contains 380 items organized in 16 subtests. All items are administered in a single test…

  14. [Development of combat medical robots in the US Armed Forces].

    PubMed

    Golota, A S; Ivchenko, E V; Krassiĭ, A B; Kuvakin, V I; Soldatov, E A

    2014-04-01

    The current article is dedicated to the problem of scientific research organization in the field of combat medical robots development in the US Armed Forces. The role of the Telemedicine and Advanced Technology Research Center is singled out. The project A Robotic System for Wounded Patient Extraction and Evacuation from Hostile Environments is described in more detail. It is noted the high cost of such technical systems development and operation.

  15. Developments of a force image algorithm for micromachined optical bend loss sensor

    NASA Astrophysics Data System (ADS)

    Huang, Chu-Yu; Liu, Chao-Shih; Panergo, Reynold; Huang, Cheng-Sheng; Wang, Wei-Chih

    2005-05-01

    A flexible high-resolution sensor capable of measuring the distribution of both shear and pressure at the plantar interface are needed to study the actual distribution of this force during daily activities, and the role that shear plays in causing plantar ulceration. We have previously developed a novel means of transducing plantar shear and pressure stress via a new microfabricated optical system. However, a force image algorithm is needed to handle the complexity of construction of two-dimensional planar pressure and shear images. Here we have developed a force image algorithm for a micromachined optical bend loss sensor. A neural network is introduced to help identify different load shapes. According to the experimental result, we can conclude that once the neural network has been well trained, it can correctly identify the loading shape. With the neural network, our micromachined optical bend loss Sensor is able to construction the two-dimensional planar force images.

  16. Development of a Refined Space Vehicle Rollout Forcing Function

    NASA Technical Reports Server (NTRS)

    James, George; Tucker, Jon-Michael; Valle, Gerard; Grady, Robert; Schliesing, John; Fahling, James; Emory, Benjamin; Armand, Sasan

    2016-01-01

    For several decades, American manned spaceflight vehicles and the associated launch platforms have been transported from final assembly to the launch pad via a pre-launch phase called rollout. The rollout environment is rich with forced harmonics and higher order effects can be used for extracting structural dynamics information. To enable this utilization, processing tools are needed to move from measured and analytical data to dynamic metrics such as transfer functions, mode shapes, modal frequencies, and damping. This paper covers the range of systems and tests that are available to estimate rollout forcing functions for the Space Launch System (SLS). The specific information covered in this paper includes: the different definitions of rollout forcing functions; the operational and developmental data sets that are available; the suite of analytical processes that are currently in-place or in-development; and the plans and future work underway to solve two immediate problems related to rollout forcing functions. Problem 1 involves estimating enforced accelerations to drive finite element models for developing design requirements for the SLS class of launch vehicles. Problem 2 involves processing rollout measured data in near real time to understand structural dynamics properties of a specific vehicle and the class to which it belongs.

  17. 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.

  18. Akt activation prevents the force drop induced by eccentric contractions in dystrophin-deficient skeletal muscle.

    PubMed

    Blaauw, Bert; Mammucari, Cristina; Toniolo, Luana; Agatea, Lisa; Abraham, Reimar; Sandri, Marco; Reggiani, Carlo; Schiaffino, Stefano

    2008-12-01

    Skeletal muscles of the mdx mouse, a model of Duchenne Muscular Dystrophy, show an excessive reduction in the maximal tetanic force following eccentric contractions. This specific sign of the susceptibility of dystrophin-deficient muscles to mechanical stress can be used as a quantitative test to measure the efficacy of therapeutic interventions. Using inducible transgenesis in mice, we show that when Akt activity is increased the force drop induced by eccentric contractions in mdx mice becomes similar to that of wild-type mice. This effect is not correlated with muscle hypertrophy and is not blocked by rapamycin treatment. The force drop induced by eccentric contractions is similar in skinned muscle fibers from mdx and Akt-mdx mice when stretch is applied directly to skinned fibers. However, skinned fibers isolated from mdx muscles exposed to eccentric contractions in vivo develop less isometric force than wild-type fibers and this force depression is completely prevented by Akt activation. These experiments indicate that the myofibrillar-cytoskeletal system of dystrophin-deficient muscle is highly susceptible to a damage caused by eccentric contraction when elongation is applied in vivo, and this damage can be prevented by Akt activation. Microarray and PCR analyses indicate that Akt activation induces up-regulation of genes coding for proteins associated with Z-disks and costameres, and for proteins with anti-oxidant or chaperone function. The protein levels of utrophin and dysferlin are also increased by Akt activation.

  19. Video: Animals; Electric Current; Force; Science Activities. Learning in Science Project. Working Papers 51-54.

    ERIC Educational Resources Information Center

    Bell, Beverley; And Others

    Four papers to be used in conjunction with video-tapes developed by the Learning in Science Project are presented. Topic areas of the papers focus on: (1) animals; (2) electric current; (3) force; and (4) science activities. The first paper presents transcripts of class discussions focusing on the scientific meaning of the word animal. The second…

  20. 16 CFR 1211.13 - Inherent force activated secondary door sensors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Inherent force activated secondary door... § 1211.13 Inherent force activated secondary door sensors. (a) Normal operation test. (1) A force... when the door applies a 15 pound (66.7 N) or less force in the down or closing direction and when...

  1. Effect of Strength Training on Rate of Force Development in Older Women

    ERIC Educational Resources Information Center

    Gurjao, Andre Luiz Demantova; Gobbi, Lilian Teresa Bucken; Carneiro, Nelson Hilario; Goncalves, Raquel; Ferreira de Moura, Rodrigo; Cyrino, Edilson Serpeloni; Altimari, Leandro Ricardo; Gobbi, Sebastiao

    2012-01-01

    We analyzed the effect of an 8-week strength training (ST) program on the rate of force development (RFD) and electromyographic activity (EMG) in older women. Seventeen women (M age = 63.4 years, SD = 4.9) without previous ST experience were randomly assigned to either a control (n = 7) or training (n = 10) group. A leg-press isometric test was…

  2. Logistics in Security Force Assistance: Sustainable Partner Development

    DTIC Science & Technology

    2014-05-22

    by the American military centers on how well our partners learn to provide for themselves logistically. Developing a partner security force with...reductions. SFA is a critical tool in the American foreign policy kit bag. Ensuring that future efforts are informed by history, theory , doctrine...governmental duties and even less experience dealing with Korean culture and language , yet they had made a good start. Organization As the American

  3. Modulation of post‐movement beta rebound by contraction force and rate of force development

    PubMed Central

    Fry, Adam; Mullinger, Karen J.; O'Neill, George C.; Barratt, Eleanor L.; Morris, Peter G.; Bauer, Markus; Folland, Jonathan P.

    2016-01-01

    Abstract Movement induced modulation of the beta rhythm is one of the most robust neural oscillatory phenomena in the brain. In the preparation and execution phases of movement, a loss in beta amplitude is observed [movement related beta decrease (MRBD)]. This is followed by a rebound above baseline on movement cessation [post movement beta rebound (PMBR)]. These effects have been measured widely, and recent work suggests that they may have significant importance. Specifically, they have potential to form the basis of biomarkers for disease, and have been used in neuroscience applications ranging from brain computer interfaces to markers of neural plasticity. However, despite the robust nature of both MRBD and PMBR, the phenomena themselves are poorly understood. In this study, we characterise MRBD and PMBR during a carefully controlled isometric wrist flexion paradigm, isolating two fundamental movement parameters; force output, and the rate of force development (RFD). Our results show that neither altered force output nor RFD has a significant effect on MRBD. In contrast, PMBR was altered by both parameters. Higher force output results in greater PMBR amplitude, and greater RFD results in a PMBR which is higher in amplitude and shorter in duration. These findings demonstrate that careful control of movement parameters can systematically change PMBR. Further, for temporally protracted movements, the PMBR can be over 7 s in duration. This means accurate control of movement and judicious selection of paradigm parameters are critical in future clinical and basic neuroscientific studies of sensorimotor beta oscillations. Hum Brain Mapp 37:2493–2511, 2016. © 2016 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc PMID:27061243

  4. Development of Field Excavator with Embedded Force Measurement

    NASA Technical Reports Server (NTRS)

    Johnson, K.; Creager, C.; Izadnegahdar, A.; Bauman, S.; Gallo, C.; Abel, P.

    2012-01-01

    A semi-intelligent excavation mechanism was developed for use with the NASA-built Centaur 2 rover prototype. The excavator features a continuously rotatable large bucket supported between two parallel arms, both of which share a single pivot axis near the excavator base attached to the rover. The excavator is designed to simulate the collection of regolith, such as on the Moon, and to dump the collected soil into a hopper up to one meter tall for processing to extract oxygen. Because the vehicle can be autonomous and the terrain is generally unknown, there is risk of damaging equipment or using excessive power when attempting to extract soil from dense or rocky terrain. To minimize these risks, it is critical for the rover to sense the digging forces and adjust accordingly. It is also important to understand the digging capabilities and limitations of the excavator. This paper discusses the implementation of multiple strain gages as an embedded force measurement system in the excavator's arms. These strain gages can accurately measure and resolve multi-axial forces on the excavator. In order to validate these sensors and characterize the load capabilities, a series of controlled excavation tests were performed at Glenn Research Center with the excavator at various depths and cut angles while supported by a six axis load cell. The results of these tests are both compared to a force estimation model and used for calibration of the embedded strain gages. In addition, excavation forces generated using two different types of bucket edge (straight vs. with teeth) were compared.

  5. Shortening amplitude affects the incomplete force recovery after active shortening in mouse soleus muscle.

    PubMed

    Van Noten, Pieter; Van Leemputte, Marc

    2009-12-11

    Compared to isometric contraction, the force producing capacity of muscle is reduced (force depression, FD) after a work producing shortening phase. It has been suggested that FD results from an inhibition of cross-bridge binding. Because the rate constants of the exponential force (re)development are thought to be primarily determined by cross-bridge attachment/detachment rate, we aimed to investigate the components of force redevelopment (REDEV) after 0.6, 1.2 and 2.4mm shortening, resulting in varying amounts of FD (from about 5% to about 16%), in mouse soleus muscle (n=11). Compared to isometric force development (DEV), the time to reach steady-state during REDEV was about 3 times longer (370 versus 1261ms) increasing with increasing amplitude. Contrary to a single, a double exponential function with one component set equal to the rate constant of DEV (14.3s(-1)), accurately described REDEV (RMS<0.8%). The rate constant of the additional slow component decreased with increasing shortening amplitude and was associated with work delivered during shortening (R(2)=0.75) and FD (R(2)=0.77). We concluded that a work related slow exponential component is induced to the trajectory of incomplete force recovery after shortening, causing FD. These results suggest that after shortening, aside from cross-bridges with normal attachment/detachment rate, cross-bridges with reduced cycling rate are active.

  6. Influence of bite force on jaw muscle activity ratios in subject-controlled unilateral isometric biting.

    PubMed

    Chen, Lei; Pröschel, Peter Alfred; Morneburg, Thomas Riccardo

    2010-10-01

    Ratios of muscle activities in unilateral isometric biting are assumed to provide information on strategies of muscle activation independently from bite force. If valid, this assumption would facilitate experiments as it would justify subject-control instead of transducer-based force control in biting studies. As force independence of ratios is controversial, we tested whether activity ratios are associated with bite force and whether this could affect findings based on subject-controlled force. In 52 subjects, bite force and bilateral masseter and temporalis electromyograms were recorded during unilateral biting on a transducer with varying force levels and with uniform subject-controlled force. Working/balancing and temporalis/masseter ratios of activity peaks were related to bite force peaks. Activity ratios were significantly but weakly correlated with the bite force. The subject-controlled force varied within +/-25% around the prescribed force in 95% of all bites. This scatter could cause a variation of group mean activity ratios of at most +/-6% because of the weak correlation between bite force and ratios. As this small variation is negligible in most cases, subject-control of bite force can be considered an appropriate method to obtain group means of relative muscle activation in particular when force control with transducers is not feasible.

  7. Varenicline has antidepressant-like activity in the forced swim test and augments sertraline's effect.

    PubMed

    Rollema, Hans; Guanowsky, Victor; Mineur, Yann S; Shrikhande, Alka; Coe, Jotham W; Seymour, Patricia A; Picciotto, Marina R

    2009-03-01

    Varenicline, an alpha4beta2 nicotinic acetylcholine receptor partial agonist developed as a smoking cessation aid, showed antidepressant-like activity in the forced swim test in two mouse strains. In addition, a low varenicline dose significantly enhanced the effects of moderately active doses of the selective serotonin reuptake inhibitor sertraline. These findings are consistent with the notion that reducing alpha4beta2 nicotinic acetylcholine receptor activity either by antagonists or by partial agonists that can partially activate or desensitize acetylcholine receptors is associated with antidepressant-like properties. These data suggest that varenicline may have antidepressant potential and can, when combined, augment antidepressant responses of selective serotonin reuptake inhibitors.

  8. Political Activities by Members of the Armed Forces on Active Duty

    DTIC Science & Technology

    1990-06-15

    an election day. 13. Solicit or otherwise engage in fundraising activities in Federal offices or facilities, including military reservations, for a...actively promote, political dinners and similar fundraising events. 18. Attend partisan political events as an official representative of the Armed Forces

  9. Space station operations task force. Panel 3 report: User development and integration

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The User Development and Integration Panel of the Space Station Operations Task Force was chartered to develop concepts relating to the operations of the Space Station manned base and the platforms, user accommodation and integration activities. The needs of the user community are addressed in the context with the mature operations phase of the Space Station. Issues addressed include space station pricing options, marketing strategies, payload selection and resource allocation options, and manifesting techniques.

  10. Development of accurate force fields for the simulation of biomineralization.

    PubMed

    Raiteri, Paolo; Demichelis, Raffaella; Gale, Julian D

    2013-01-01

    The existence of an accurate force field (FF) model that reproduces the free-energy landscape is a key prerequisite for the simulation of biomineralization. Here, the stages in the development of such a model are discussed including the quality of the water model, the thermodynamics of polymorphism, and the free energies of solvation for the relevant species. The reliability of FFs can then be benchmarked against quantities such as the free energy of ion pairing in solution, the solubility product, and the structure of the mineral-water interface.

  11. Theater Nuclear Force Survivability and Security Instrumentation. Engineering Development Phase.

    DTIC Science & Technology

    1980-05-15

    THIS SHEET LINVENTORY o - Aproved I oi ;~ziTic :~ o |. .. Distiibutio,-; ni ,t, DISTRIBUTION STATEMENT ACCESSION FOR NTIS GRA&I DTIC T"A D UNANNOUNCED...H 81 2 O 01 " DATE KECEIVED IN DTIC PHOTOGRAPH THIS SHEET AND RETURN TO DTIC-DDA-2 FORM DOCUMENT PROCESSING SHEET DTIC OCT 79 70A h-10( 4.c DNA 5158F...THEATER NUCLEAR FORCE SURVIVABILITY SAND SECURITY INSTRUMENTATION ’ Engineering Development Phase o rhe BDM Corporation ’.0. Box 9274 kibuquerque

  12. U.S. Strategic Nuclear Forces: Background, Developments, and Issues

    DTIC Science & Technology

    2016-03-10

    the size and structure of the U.S. nuclear force , and a review of U.S. nuclear employment policy, in June 2013. This review has advised the force ...Strategic Triad ..................................................................................................... 2 Force Structure and Size During...the Cold War ......................................................................... 2 Force Structure and Size After the Cold War

  13. The Early Development of Satellite Characterization Capabilities at the Air Force Laboratories

    NASA Astrophysics Data System (ADS)

    Lambert, J.; Kissell, K.

    This presentation overviews the development of optical Space Object Identification (SOI) techniques at the Air Force laboratories during the two-decade "pre-operational" period prior to 1980 when the Groundbased Electro-Optical Deep Space Surveillance (GEODSS) sensors were deployed. Beginning with the launch of Sputnik in 1957, the United States Air Force has actively pursued the development and application of optical sensor technology for the detection, tracking, and characterization of artificial satellites. Until the mid-1980s, these activities were primarily conducted within Air Force research and development laboratories which supplied data to the operational components on a contributing basis. This presentation traces the early evolution of the optical space surveillance technologies from the early experimental sensors that led to the current generation of operationally deployed and research systems. The contributions of the participating Air Force organizations and facilities will be reviewed with special emphasis on the development of technologies for the characterization of spacecraft using optical signatures and imagery. The presentation will include descriptions and photographs of the early facilities and instrumentation, and examples of the SOI collection and analysis techniques employed. In this early period, computer support was limited so all aspects of space surveillance relied heavily on manual interaction. Many military, government, educational, and contractor agencies supported the development of instrumentation and analysis techniques. This overview focuses mainly on the role played by Air Force System Command and Office of Aerospace Research, and the closely related activities at the Department of Defense Advanced Research Projects Agency. The omission of other agencies from this review reflects the limitations of this presentation, not the significance of their contributions.

  14. Dissolution study of active pharmaceutical ingredients using molecular dynamics simulations with classical force fields

    NASA Astrophysics Data System (ADS)

    Greiner, Maximilian; Elts, Ekaterina; Schneider, Julian; Reuter, Karsten; Briesen, Heiko

    2014-11-01

    The CHARMM, general Amber and OPLS force fields are evaluated for their suitability in simulating the molecular dynamics of the dissolution of the hydrophobic, small-molecule active pharmaceutical ingredients aspirin, ibuprofen, and paracetamol in aqueous media. The force fields are evaluated by comparison with quantum chemical simulations or experimental references on the basis of the following capabilities: accurately representing intra- and intermolecular interactions, appropriately reproducing crystal lattice parameters, adequately describing thermodynamic properties, and the qualitative description of the dissolution behavior. To make this approach easily accessible for evaluating the dissolution properties of novel drug candidates in the early stage of drug development, the force field parameter files are generated using online resources such as the SWISS PARAM servers, and the software packages ACPYPE and Maestro. All force fields are found to reproduce the intermolecular interactions with a reasonable degree of accuracy, with the general Amber and CHARMM force fields showing the best agreement with quantum mechanical calculations. A stable crystal bulk structure is obtained for all model substances, except for ibuprofen, where the reproductions of the lattice parameters and observed crystal stability are considerably poor for all force fields. The heat of solution used to evaluate the solid-to-solution phase transitions is found to be in qualitative agreement with the experimental data for all combinations tested, with the results being quantitatively optimum for the general Amber and CHARMM force fields. For aspirin and paracetamol, stable crystal-water interfaces were obtained. The (100), (110), (011) and (001) interfaces of aspirin or paracetamol and water were simulated for each force field for 30 ns. Although generally expected as a rare event, in some of the simulations, dissolution is observed at 310 K and ambient pressure conditions.

  15. Air Force Organizational Transformation: Merging the Active and Reserve Components

    DTIC Science & Technology

    2007-11-02

    34Future Total Force." 18 34 Ibid. 35 Ibid. 36 John A. Tirpak, "The Blended Wing Goes to War," Air Force Magazine, October 2003. [ Jounal on-line...Space Power 3 (Fall 2004): 41-53. Tirpak, John A. "The Blended Wing Goes to War," Air Force Magazine, October 2003. Jounal on-line. Available from

  16. Quantification of Cyclic Ground Reaction Force Histories During Daily Activity in Humans

    NASA Technical Reports Server (NTRS)

    Breit, G. A.; Whalen, R. T.; Wade, Charles E. (Technical Monitor)

    1994-01-01

    Theoretical models and experimental studies of bone remodeling suggest that bone density and structure are influenced by local cyclic skeletal tissue stress and strain histories. Estimation of long-term loading histories in humans is usually achieved by assessment of physical activity level by questionnaires, logbooks, and pedometers, since the majority of lower limb cyclic loading occurs during walking and running. These methods provide some indication of the mechanical loading history, but fail to consider the true magnitude of the lower limb skeletal forces generated by various daily activities. These techniques cannot account for individual gait characteristics, gait speed, and unpredictable high loading events that may influence bone mass significantly. We have developed portable instrumentation to measure and record the vertical component of the ground reaction force (GRFz) during normal daily activity. This equipment allows long-term quantitative monitoring of musculoskeletal loads, which in conjunction with bone mineral density assessments, promises to elucidate the relationship between skeletal stresses and bone remodeling.

  17. Force-endurance capabilities of extravehicular activity (EVA) gloves at different pressure levels

    NASA Technical Reports Server (NTRS)

    Bishu, Ram R.; Klute, Glenn K.

    1993-01-01

    The human hand is a very useful multipurpose tool in all environments. However, performance capabilities are compromised considerably when gloves are donned. This is especially true to extravehicular activity (EVA) gloves. The primary intent was to answer the question of how long a person can perform tasks requiring certain levels of exertion. The objective was to develop grip force-endurance relations. Six subjects participated in a factorial experiment involving three hand conditions, three pressure differentials, and four levels of force exertion. The results indicate that, while the force that could be exerted depended on the glove, pressure differential, and the level of exertion, the endurance time at any exertion level depended just on the level of exertion expressed as a percentage of maximum exertion possible at that condition. The impact of these findings for practitioners as well as theoreticians is discussed.

  18. Positive force feedback in development of substrate grip in the stick insect tarsus.

    PubMed

    Zill, Sasha N; Chaudhry, Sumaiya; Exter, Annelie; Büschges, Ansgar; Schmitz, Josef

    2014-09-01

    The mechanics of substrate adhesion has recently been intensively studied in insects but less is known about the sensorimotor control of substrate engagement. We characterized the responses and motor effects of tarsal campaniform sensilla in stick insects to understand how sensory signals of force could contribute to substrate grip. The tarsi consist of a chain of segments linked by highly flexible articulations. Morphological studies showed that one to four campaniform sensilla are located on the distal end of each segment. Activities of the receptors were recorded neurographically and sensilla were identified by stimulation and ablation of their cuticular caps. Responses were characterized to bending forces and axial loads, muscle contractions and to forces applied to the retractor apodeme (tendon). The tarsal sensilla effectively encoded both the rate and amplitude of loads and muscle forces, but only when movement was resisted. Mechanical stimulation of the receptors produced activation of motor neurons in the retractor unguis and tibial flexor muscles. These findings indicate that campaniform sensilla can provide information about the effectiveness of the leg muscles in generating substrate adherence. They can also produce positive force feedback that could contribute to the development of substrate grip and stabilization of the tarsal chain.

  19. Iraqi Security Forces: Police Training Program Developed Sizeable Force, but Capabilities Are Unknown

    DTIC Science & Technology

    2010-10-25

    Iraq Training and Advisory Mission ( ITAM ), under U.S. Forces-Iraq (USF-I), is responsible for managing the program for DoD. On October 1, 2011...MOI and its forces over the next year. The STTs will be responsible for day-to-day management of the police advisors while ITAM will be responsible...transitioned to the Iraq Training and Advisory Mission ( ITAM ). In January 2010, the Multi-National Force-Iraq transitioned to the U.S. Force-Iraq (USF

  20. Women's labour force participation and socioeconomic development: the case of Peninsular Malaysia, 1957-1970.

    PubMed

    Hirschman, C; Aghajanian, A

    1980-03-01

    Changes in labor force participation of Malay, Chinese and Indian women in the agricultural and nonagricultural sectors in Peninsular Malaysia, based on the 1957 and 1970 censuses, are analyzed. Brief discussions of the relation between economic development and female labor force participation, the socioeconomic development and ethnic composition of Malaysia, and past research on women's labor force participation in Peninsular Malaysia provide background for the analysis. The overall participation rate of women aged 15 to 64 rose from 31% in 1957 to 37% in 1970, with most of the increase among younger women. Participation rates rose for Malay women at all ages, dropped sharply for Indian women at all ages, and rose for Chinese women below age 40 but declined thereafter. Trends in Chinese female labor force activity seem to fit the developmental model most closely; Malay employment in agriculture among middle-aged women probably appeared to increase due to underestimation in the 1957 census; and Indian participation declined due to a sharp curtailment of the entire plantation labor force. Cross sectional analysis using the 1970 2% census sample demonstrates that rural residence, low educational level, and married status are associated with employment in the traditional and modern agricultural sectors. Higher educational attainment, urban residence, and delayed marriage are associated with employment in the modern non-agricultural sector. Chinese women had higher proportions in the modern sector.

  1. Interaction of Rate of Force Development and Duration of Rate in Isometric Force.

    ERIC Educational Resources Information Center

    Siegel, Donald

    A study attempted to determine whether force and duration parameters are programmed in an interactive or independent fashion prior to executing ballistic type isometric contractions of graded intensities. Four adult females each performed 360 trials of producing ballistic type forces representing 25, 40, 55, and 75 percent of their maximal…

  2. The Impact of the Developmental Training Model on Staff Development in Air Force Child Development Programs

    ERIC Educational Resources Information Center

    Bird, Candace Maria Edmonds

    2010-01-01

    In an effort to standardize training delivery and to individualize staff development based on observation and reflective practice, the Air Force implemented the Developmental Training Model (DTM) in its Child Development Programs. The goal of the Developmental Training Model is to enhance high quality programs through improvements in the training…

  3. Regionalizing muscle activity causes changes to the magnitude and direction of the force from whole muscles—a modeling study

    PubMed Central

    Rahemi, Hadi; Nigam, Nilima; Wakeling, James M.

    2014-01-01

    Skeletal muscle can contain neuromuscular compartments that are spatially distinct regions that can receive relatively independent levels of activation. This study tested how the magnitude and direction of the force developed by a whole muscle would change when the muscle activity was regionalized within the muscle. A 3D finite element model of a muscle with its bounding aponeurosis was developed for the lateral gastrocnemius, and isometric contractions were simulated for a series of conditions with either a uniform activation pattern, or regionally distinct activation patterns: in all cases the mean activation from all fibers within the muscle reached 10%. The models showed emergent features of the fiber geometry that matched physiological characteristics: with fibers shortening, rotating to greater pennation, adopting curved trajectories in 3D and changes in the thickness and width of the muscle belly. Simulations were repeated for muscle with compliant, normal and stiff aponeurosis and the aponeurosis stiffness affected the changes to the fiber geometry and the resultant muscle force. Changing the regionalization of the activity resulted to changes in the magnitude, direction and center of the force vector from the whole muscle. Regionalizing the muscle activity resulted in greater muscle force than the simulation with uniform activity across the muscle belly. The study shows how the force from a muscle depends on the complex interactions between the muscle fibers and connective tissues and the region of muscle that is active. PMID:25232341

  4. Regionalizing muscle activity causes changes to the magnitude and direction of the force from whole muscles-a modeling study.

    PubMed

    Rahemi, Hadi; Nigam, Nilima; Wakeling, James M

    2014-01-01

    Skeletal muscle can contain neuromuscular compartments that are spatially distinct regions that can receive relatively independent levels of activation. This study tested how the magnitude and direction of the force developed by a whole muscle would change when the muscle activity was regionalized within the muscle. A 3D finite element model of a muscle with its bounding aponeurosis was developed for the lateral gastrocnemius, and isometric contractions were simulated for a series of conditions with either a uniform activation pattern, or regionally distinct activation patterns: in all cases the mean activation from all fibers within the muscle reached 10%. The models showed emergent features of the fiber geometry that matched physiological characteristics: with fibers shortening, rotating to greater pennation, adopting curved trajectories in 3D and changes in the thickness and width of the muscle belly. Simulations were repeated for muscle with compliant, normal and stiff aponeurosis and the aponeurosis stiffness affected the changes to the fiber geometry and the resultant muscle force. Changing the regionalization of the activity resulted to changes in the magnitude, direction and center of the force vector from the whole muscle. Regionalizing the muscle activity resulted in greater muscle force than the simulation with uniform activity across the muscle belly. The study shows how the force from a muscle depends on the complex interactions between the muscle fibers and connective tissues and the region of muscle that is active.

  5. Effect of Knee Position on Quadriceps Muscle Force Steadiness and Activation Strategies

    PubMed Central

    Krishnan, Chandramouli; Allen, Eric J.; Williams, Glenn N.

    2010-01-01

    Introduction This study investigated the effect of knee position on quadriceps force steadiness and activation strategies. Methods Quadriceps force steadiness was evaluated in twenty-two volunteers at two knee positions by testing their ability to regulate submaximal force. Muscle activation strategies were studied in both time and frequency domains using surface electromyography. Results Quadriceps force fluctuations and the associated agonist and antagonist activity were significantly higher at 90° than at 30° of flexion (P < 0.05). The quadriceps median frequency recorded at 30° was significantly higher than at 90° of flexion (P < 0.05). Regression analyses revealed that force steadiness was related to quadriceps activation and median frequency (P < 0.001), but not to hamstring coactivation (P > 0.05). Discussion The results indicate that knee position significantly affects quadriceps force steadiness and activation strategies. This finding may have important implications for designing a force control testing protocol and interpreting test results. PMID:21404288

  6. Mechanical forces regulate elastase activity and binding site availability in lung elastin.

    PubMed

    Jesudason, Rajiv; Sato, Susumu; Parameswaran, Harikrishnan; Araujo, Ascanio D; Majumdar, Arnab; Allen, Philip G; Bartolák-Suki, Erzsébet; Suki, Béla

    2010-11-03

    Many fundamental cellular and extracellular processes in the body are mediated by enzymes. At the single molecule level, enzyme activity is influenced by mechanical forces. However, the effects of mechanical forces on the kinetics of enzymatic reactions in complex tissues with intact extracellular matrix (ECM) have not been identified. Here we report that physiologically relevant macroscopic mechanical forces modify enzyme activity at the molecular level in the ECM of the lung parenchyma. Porcine pancreatic elastase (PPE), which binds to and digests elastin, was fluorescently conjugated (f-PPE) and fluorescent recovery after photobleach was used to evaluate the binding kinetics of f-PPE in the alveolar walls of normal mouse lungs. Fluorescent recovery after photobleach indicated that the dissociation rate constant (k(off)) for f-PPE was significantly larger in stretched than in relaxed alveolar walls with a linear relation between k(off) and macroscopic strain. Using a network model of the parenchyma, a linear relation was also found between k(off) and microscopic strain on elastin fibers. Further, the binding pattern of f-PPE suggested that binding sites on elastin unfold with strain. The increased overall reaction rate also resulted in stronger structural breakdown at the level of alveolar walls, as well as accelerated decay of stiffness and decreased failure stress of the ECM at the macroscopic scale. These results suggest an important role for the coupling between mechanical forces and enzyme activity in ECM breakdown and remodeling in development, and during diseases such as pulmonary emphysema or vascular aneurysm. Our findings may also have broader implications because in vivo, enzyme activity in nearly all cellular and extracellular processes takes place in the presence of mechanical forces.

  7. 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)

  8. Enhancing the Capacity of Four-Year Postsecondary Educational Institutions to Promote Economic Development. A Report by the Task Force on Education and Economic Development.

    ERIC Educational Resources Information Center

    Southern Education Foundation, Atlanta, GA.

    This report discusses efforts undertaken by the Southern Education Foundation's (SEF) Task Force on Education and Economic Development and summarizes case-study reports of activities at four-year, postsecondary educational institutions in the South to promote economic development. The activities of six institutions were reviewed: Jackson State…

  9. Force regulation of ankle extensor muscle activity in freely walking cats.

    PubMed

    Donelan, J M; McVea, D A; Pearson, K G

    2009-01-01

    To gain insight into the relative importance of force feedback to ongoing ankle extensor activity during walking in the conscious cat, we isolated the medial gastrocnemius muscle (MG) by denervating the other ankle extensors and measured the magnitude of its activity at different muscle lengths, velocities, and forces accomplished by having the animals walk up and down a sloped pegway. Mathematical models of proprioceptor dynamics predicted afferent activity and revealed that the changes in muscle activity under our experimental conditions were strongly correlated with Ib activity and not consistently associated with changes in Ia or group II activity. This allowed us to determine the gains within the force feedback pathway using a simple model of the neuromuscular system and the measured relationship between MG activity and force. Loop gain increased with muscle length due to the intrinsic force-length property of muscle. The gain of the pathway that converts muscle force to motoneuron depolarization was independent of length. To better test for a causal relationship between modulation of force feedback and changes in muscle activity, a second set of experiments was performed in which the MG muscle was perturbed during ground contact of the hind foot by dropping or lifting the peg underfoot. Collectively, these investigations support a causal role for force feedback and indicate that about 30% of the total muscle activity is due to force feedback during level walking. Force feedback's role increases during upslope walking and decreases during downslope walking, providing a simple mechanism for compensating for changes in terrain.

  10. Vehicle active suspension system using skyhook adaptive neuro active force control

    NASA Astrophysics Data System (ADS)

    Priyandoko, G.; Mailah, M.; Jamaluddin, H.

    2009-04-01

    This paper aims to highlight the practical viability of a new and novel hybrid control technique applied to a vehicle active suspension system of a quarter car model using skyhook and adaptive neuro active force control (SANAFC). The overall control system essentially comprises four feedback control loops, namely the innermost proportional-integral (PI) control loop for the force tracking of the pneumatic actuator, the intermediate skyhook and active force control (AFC) control loops for the compensation of the disturbances and the outermost proportional-integral-derivative (PID) control loop for the computation of the optimum target/commanded force. A neural network (NN) with a modified adaptive Levenberg-Marquardt learning algorithm was used to approximate the estimated mass and inverse dynamics of the pneumatic actuator in the AFC loop. A number of experiments were carried out on a physical test rig using a hardware-in-the-loop configuration that fully incorporates the theoretical elements. The performance of the proposed control method was evaluated and compared to examine the effectiveness of the system in suppressing the vibration effect on the suspension system. It was found that the simulation and experimental results were in good agreement, particularly for the sprung mass displacement and acceleration behaviours in which the proposed SANAFC scheme is found to outperform the PID and passive counterparts.

  11. The senses of active and passive forces at the human ankle joint.

    PubMed

    Savage, G; Allen, T J; Proske, U

    2015-07-01

    The traditional view of the neural basis for the sense of muscle force is that it is generated at least in part within the brain. Recently it has been proposed that force sensations do not arise entirely centrally and that there is a contribution from peripheral receptors within the contracting muscle. Evidence comes from experiments on thumb flexor and elbow flexor muscles. Here we have studied the sense of force in plantar flexor muscles of the human ankle, looking for further evidence for such a mechanism. The active angle-torque curve was measured for muscles of both legs, and for each muscle, ankle angles were identified on the ascending and descending limbs of the curve where active forces were similar. In a plantar flexion force matching task, subjects were asked to match the force in one foot, generated on the ascending limb of the curve, with force in the other foot, generated on the descending limb. It was hypothesised that despite active forces being similar, the sensation generated in the more stretched muscle should be greater because of the contribution from its peripheral stretch receptors, leading to an overestimation of the force in the stretched muscle. It was found that provided that the comparison was between active forces, there was no difference in the forces generated by the two legs, supporting the central hypothesis for the sense of force. When total forces were matched, including a component of passive force due to muscle stretch, subjects seemed to ignore the passive component. Yet subjects had an acute sense of passive force, provided that the muscles remained relaxed. It was concluded that subjects had two senses, a sense of active force, generated centrally, and a sense of passive force, or perhaps muscle stretch, generated within the muscle itself.

  12. Single-molecule kinetics under force: probing protein folding and enzymatic activity with optical tweezers

    NASA Astrophysics Data System (ADS)

    Wong, Wesley

    2010-03-01

    Weak non-covalent bonds between and within single molecules govern many aspects of biological structure and function (e.g. DNA base-paring, receptor-ligand binding, protein folding, etc.) In living systems, these interactions are often subject to mechanical forces, which can greatly alter their kinetics and activity. My group develops and applies novel single-molecule manipulation techniques to explore and quantify these force-dependent kinetics. Using optical tweezers, we have quantified the force-dependent unfolding and refolding kinetics of different proteins, including the cytoskeletal protein spectrin in collaboration with E. Evans's group [1], and the A2 domain of the von Willebrand factor blood clotting protein in collaboration with T. Springer's group [2]. Furthermore, we have studied the kinetics of the ADAMTS13 enzyme acting on a single A2 domain, and have shown that physiolgical forces in the circulation can act as a cofactor for enzymatic cleavage, regulating hemostatic activity [2]. References: 1. E. Evans, K. Halvorsen, K. Kinoshita, and W.P. Wong, Handbook of Single Molecule Biophysics, P. Hinterdorfer, ed., Springer (2009). 2. X. Zhang, K. Halvorsen, C.-Z. Zhang, W.P. Wong, and T.A. Springer, Science 324 (5932), 1330-1334 (2009).

  13. Prototypes of Cognitive Measures for Air Force Officers: Test Development and Item Banking

    DTIC Science & Technology

    1990-05-01

    AFHRL-TP-89-737 3, COPY AIR FORCE PROTOTYPES OF COGNITIVE MEASURES FOR AIR FORCE OFFICERS: TEST DEVELOPMENT AND ITEM BANKING DTIC f1 ELECTF H Frances...Jacobina Skinner MANPOWER AND PERSONNEL DIVISION R Brooks Air Force Base, Texas 78235-5601 E S O May 1990U Final Technical Paper for Period September 1987...November 1989 R C Approved for public release; distribution is unlimited. E S LABORATORY AIR FORCE SYSTEMS COMMAND BROOKS AIR FORCE BASE, TEXAS

  14. Development of Force Reflecting Joystick for Hydraulic Excavator

    NASA Astrophysics Data System (ADS)

    Ahn, Kyoungkwan

    In teleoperation field robotic system such as hydraulically actuated robotic excavator, the maneuverability and convenience is the most important in the operation of robotic excavator. Particularly the force information is important in dealing with digging and leveling operation in the teleoperated excavator. This paper presents a new force reflecting joystick in a velocity-force type bilateral teleoperation system. The master system is electrical joystick and the slave system is hydraulic cylinder. Particularly pneumatic motor is used newly in the master joystick for force reflection and the information of the pressure of slave cylinder is measured and utilized as force feedback signal. This paper also proposes a novel force-reflection gain selecting algorithm based on artificial neural network. Finally a series of experiments are conducted under various load conditions using a laboratory-made one axis slave cylinder and load simulator.

  15. Development of the Air Force Contingency Contracting Course Framework

    DTIC Science & Technology

    1993-09-01

    AUTHOR(S) 7.PERFORMING ORGANIZATION NAME(S) AND ADORESS(ES) B. PERFORMING ORGANIZATION REPORT NUMBER Air Force Institute of Technology , WPAFB OH 45433...Logistics and Acquisition Management of the Air Force Institute of Technology Air Education and Training Command I- 0 artial Fulfillment of the...officers that were deployed in support of the contingency, as well as other more recent Air Force Institute of Technology 1AFIT) theses, corroborated

  16. Tactical Special Operations and Conventional Force Interdependence: The Future of Land Force Development

    DTIC Science & Technology

    2013-06-14

    Conventional Forces DoD Department of Defense FID Foreign Internal Defense JP Joint Publication PME Professional Military Education SFA Security Force...and assistance to other nations. Finally, USSOCOM recently became DoD’s lead for countering threat financing in order to identify and disrupt terrorist... financing efforts (Feickert 2012, 2). The important aspect of this evolution is the observation that, as the complexity of the threat has increased

  17. Development of a measuring system of contact force during braille reading using an optical 6-axis force sensor.

    PubMed

    Watanabe, T; Oouchi, S; Yamaguchi, T; Shimojo, M; Shimada, S

    2006-01-01

    A system with an optical 6-axis force sensor was developed to measure contact force during braille reading. In using this system, we encountered two problems. One is a variability of output values depending on the contact point. This was solved by using two transformation techniques. The other is that subjects read braille in a different manner from the usual. We compared two manners of braille reading, one-handed vs two-handed, and found a small reduction in reading speed. Using this system, we collected data from four braille readers and quantitatively showed more minute contact force trajectories than those in earlier studies.

  18. 78 FR 21492 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-10

    ... ADMINISTRATION Interagency Task Force on Veterans Small Business Development AGENCY: U.S. Small Business Administration. ACTION: Notice of open Federal Interagency Task Force Meeting. SUMMARY: The SBA is issuing this... Force on Veterans Small Business Development. The meeting will be open to the public. DATES:...

  19. 78 FR 23970 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-23

    ... ADMINISTRATION Interagency Task Force on Veterans Small Business Development AGENCY: U.S. Small Business Administration. ACTION: Notice of open Federal Interagency Task Force Meeting. SUMMARY: This document corrects the SBA's Interagency Task Force on Veterans Small Business Developments notice of a public...

  20. 78 FR 70087 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-22

    ... ADMINISTRATION Interagency Task Force on Veterans Small Business Development AGENCY: U.S. Small Business Administration. ACTION: Notice of open Federal Interagency Task Force meeting. SUMMARY: The SBA is issuing this... Force on Veterans Small Business Development. The meeting will be open to the public. DATES:...

  1. 75 FR 62611 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-12

    ... ADMINISTRATION Interagency Task Force on Veterans Small Business Development AGENCY: U.S. Small Business Administration. ACTION: Notice of open Federal Interagency Task Force meeting. SUMMARY: The SBA is issuing this... Task Force on Veterans Small Business Development. The meeting will be open to the public....

  2. 76 FR 8393 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-14

    ... ADMINISTRATION Interagency Task Force on Veterans Small Business Development AGENCY: U.S. Small Business Administration. ACTION: Notice of open Federal Interagency Task Force meeting. SUMMARY: The SBA is issuing this... Task Force on Veterans Small Business Development. The meeting will be open to the public....

  3. 78 FR 45996 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-30

    ... ADMINISTRATION Interagency Task Force on Veterans Small Business Development AGENCY: U.S. Small Business Administration. ACTION: Notice of open Federal Interagency Task Force meeting. SUMMARY: The SBA is issuing this... Force on Veterans Small Business Development. The meeting will be open to the public. DATES: August...

  4. 77 FR 41472 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-13

    ... ADMINISTRATION Interagency Task Force on Veterans Small Business Development AGENCY: U.S. Small Business Administration. ACTION: Notice of open Federal Interagency Task Force meeting. SUMMARY: The SBA is issuing this... Task Force on Veterans Small Business Development. The meeting will be open to the public....

  5. Air Force Officers: Personnel Policy Development, 1944-1974

    DTIC Science & Technology

    1996-01-01

    Postwar Officer Corps, 1944-1945 ....... 7 General Arnold Confronts the Problem ....................... 9 Planning Fails to Keep Pace...Contents Photographs General of the Army Henry H. Arnold ............................ 8 General of the Army George C. Marshall...7 Air Force Officers General of the Army Henry H. Arnold , Commanding General of the Army Air Forces, 1942-1946. The problem was rooted in the prewar

  6. The National Guard: Recommendations to Develop the Joint Future Force

    DTIC Science & Technology

    2010-03-01

    author of this paper, is a requirement to educate the military personnel on total force and joint concepts from the earliest stages. Aristotle once...8 Phillip S. Meilinger, American Airpower Biography : A Survey of the Field Air and Space Power (Maxwell Air Force Base, AL: Air University Press

  7. 77 FR 71471 - Interagency Task Force on Veterans Small Business Development; Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-30

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Interagency Task Force on Veterans Small Business Development; Notice of Meeting AGENCY: U.S. Small Business Administration. ACTION: Notice of open Federal Interagency Task Force meeting....

  8. 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.

  9. Development of a force-reflecting robotic platform for cardiac catheter navigation.

    PubMed

    Park, Jun Woo; Choi, Jaesoon; Pak, Hui-Nam; Song, Seung Joon; Lee, Jung Chan; Park, Yongdoo; Shin, Seung Min; Sun, Kyung

    2010-11-01

    Electrophysiological catheters are used for both diagnostics and clinical intervention. To facilitate more accurate and precise catheter navigation, robotic cardiac catheter navigation systems have been developed and commercialized. The authors have developed a novel force-reflecting robotic catheter navigation system. The system is a network-based master-slave configuration having a 3-degree of freedom robotic manipulator for operation with a conventional cardiac ablation catheter. The master manipulator implements a haptic user interface device with force feedback using a force or torque signal either measured with a sensor or estimated from the motor current signal in the slave manipulator. The slave manipulator is a robotic motion control platform on which the cardiac ablation catheter is mounted. The catheter motions-forward and backward movements, rolling, and catheter tip bending-are controlled by electromechanical actuators located in the slave manipulator. The control software runs on a real-time operating system-based workstation and implements the master/slave motion synchronization control of the robot system. The master/slave motion synchronization response was assessed with step, sinusoidal, and arbitrarily varying motion commands, and showed satisfactory performance with insignificant steady-state motion error. The current system successfully implemented the motion control function and will undergo safety and performance evaluation by means of animal experiments. Further studies on the force feedback control algorithm and on an active motion catheter with an embedded actuation mechanism are underway.

  10. U.S. Strategic Nuclear Forces: Background, Developments, and Issues

    DTIC Science & Technology

    2012-02-22

    to less than 6,000 warheads today, and is slated to decline to 1,550 warheads by the year 2017 if the New START Treaty enters into force. At the...test program would begin to run short around 2017 or 2018. The added test assets would support the program through 2025 or longer. This time line...Adam. The Future Missile Force. Air Force Magazine. October 2005. 31 See, for example, Jeffrey Lewis. STRATCOM Hearts MIRV. ArmsControlWonk.com

  11. Conventional armed forces in Europe: Technology scenario development

    SciTech Connect

    Houser, G.M.

    1990-07-01

    In January 1986, the Soviet Union's Mikhail Gorbachev proposed elimination of all nuclear weapons by the year 2000. In April of that year, Mr. Gorbachev proposed substantial reductions of conventional weapons in Europe, from the Atlantic Ocean to the Ural Mountains, including reductions in operational-tactical nuclear weapons. In May 1986, the North Atlantic Treaty Organization (NATO) responded with the Brussels Declaration on Conventional Arms Control,'' which indicated readiness to open East/West discussions on establishing a mandate for negotiating conventional arms control throughout Europe. The Group of 23,'' which met in Vienna beginning in February 1987, concluded the meeting in January 1989 with a mandate for the Conventional Armed Forced in Europe (CFE) negotiations. On 6 March 1989, CFE talks began, and these talks have continued through six rounds (as of April 1990). Although US President George Bush, on 30 May 1989, called for agreement within six months to a year, and the Malta meeting of December 1989 called for completion of a CFE agreement by the end of 1990, much remains to be negotiated. This report provides three types of information. First, treaty provisions brought to the table by both sides are compared. Second, on the basis of these provisions, problem areas for each of the provision elements are postulated and possible scenarios for resolving these problem areas are developed. Third, the scenarios are used as requirements for tasks assigned program elements for possible US implementation of a CFE treaty. As progress is achieved during the negotiations, this report could be updated, as necessary, in each of the areas to provide a continuing systematic basis for program implementation and technology development. 8 refs.

  12. 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…

  13. Estimation of muscle forces in gait using a simulation of the electromyographic activity and numerical optimization.

    PubMed

    Ravera, Emiliano Pablo; Crespo, Marcos José; Braidot, Ariel Andrés Antonio

    2016-01-01

    Clinical gait analysis provides great contributions to the understanding of gait patterns. However, a complete distribution of muscle forces throughout the gait cycle is a current challenge for many researchers. Two techniques are often used to estimate muscle forces: inverse dynamics with static optimization and computer muscle control that uses forward dynamics to minimize tracking. The first method often involves limitations due to changing muscle dynamics and possible signal artefacts that depend on day-to-day variation in the position of electromyographic (EMG) electrodes. Nevertheless, in clinical gait analysis, the method of inverse dynamics is a fundamental and commonly used computational procedure to calculate the force and torque reactions at various body joints. Our aim was to develop a generic musculoskeletal model that could be able to be applied in the clinical setting. The musculoskeletal model of the lower limb presents a simulation for the EMG data to address the common limitations of these techniques. This model presents a new point of view from the inverse dynamics used on clinical gait analysis, including the EMG information, and shows a similar performance to another model available in the OpenSim software. The main problem of these methods to achieve a correct muscle coordination is the lack of complete EMG data for all muscles modelled. We present a technique that simulates the EMG activity and presents a good correlation with the muscle forces throughout the gait cycle. Also, this method showed great similarities whit the real EMG data recorded from the subjects doing the same movement.

  14. Analysis of Handling Qualities Design Criteria for Active Inceptor Force-Feel Characteristics

    NASA Technical Reports Server (NTRS)

    Malpica, Carlos A.; Lusardi, Jeff A.

    2013-01-01

    The force-feel system characteristics of the cyclic inceptors of most helicopters are set based on the characteristics of the mechanical components in the control system (mass, springs, friction dampers, etc.). For these helicopters, the force-feel characteristics typically remain constant over the entire flight envelope, with perhaps a trim release to minimize control forces while maneuvering. With the advent of fly-by-wire control systems and active inceptors in helicopters, the force-feel characteristics are now determined by the closed-loop response of the active inceptor itself as defined by the inertia, force/displacement gradient, damping, breakout force and detent shape configuration parameters in the inceptor control laws. These systems give the flexibility to dynamically prescribe different feel characteristics for different control modes or flight conditions, and the ability to provide tactile cueing to the pilot through the actively controlled side-stick or center-stick cyclic inceptor. For rotorcraft, a few studies have been conducted to assess the effects of cyclic force-feel characteristics on handling qualities in flight. An early study provided valuable insight into the static force-deflection characteristics (force gradient) and the number of axes controlled by the side-stick controller for the U.S. Army's Advanced Digital/Optical Control System (ADOCS) demonstrator aircraft [1]. The first of a series of studies providing insight on the inceptor dynamic force-feel characteristics was conducted on the NASA/Army CH-47B variable-stability helicopter [2]. This work led to a proposed requirement that set boundaries based on the cyclic natural frequency and inertia, with the stipulation of a lower damping ratio limit of 0.3 [3]. A second study was conducted by the Canadian Institute for Aerospace Research using their variable-stability Bell 205A helicopter [4]. This research suggested boundaries for stick dynamics based on natural frequency and damping

  15. U.S. Strategic Nuclear Forces: Background, Developments, and Issues

    DTIC Science & Technology

    2015-03-18

    2010 New START Treaty. The NPR indicated that the unique characteristics of each leg of the triad were important to the goal of maintaining...Commander, Air Force Space Command. Transcript of Speech to the National Defense University Breakfast . June 13, 2006. 46 Tom Collina, Fact Sheet: U.S...Klotz, Vice Commander, Air Force Space Command. Transcript of Speech to the National Defense University Breakfast . June 13, 2006. 51 Jason Simpson

  16. COIN in Cyberspace: Focusing Air Force Doctrine Development

    DTIC Science & Technology

    2007-01-01

    cyberspace and began codifying its cyber warfare doctrine. This effort is hampered, however, by a limited understanding of cyberspace by rank and file Air...Force members. Many believe cyberspace and cyber warfare are the responsibility of the communications community. If this new doctrine is to be...doctrine to build upon, the Air Force can create unity of effort among Airmen at all levels, ensure unity of purpose in the prosecution of cyber warfare , and

  17. U.S. Strategic Nuclear Forces: Background, Developments, and Issues

    DTIC Science & Technology

    2013-10-22

    the test program would begin to run short around 2017 or 2018. The added test assets would support the program through 2025 or longer. This time...February 2006. 33 Hebert, Adam. The Future Missile Force. Air Force Magazine. October 2005. 34 See, for example, Jeffrey Lewis. STRATCOM Hearts MIRV...transfer system, and associated cables, elastomers, valves , pads, cushions, foam supports, telemetries, and other miscellaneous parts.” The FY2012 budget

  18. 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.…

  19. Maximal force, voluntary activation and muscle soreness after eccentric damage to human elbow flexor muscles.

    PubMed

    Prasartwuth, O; Taylor, J L; Gandevia, S C

    2005-08-15

    Muscle damage reduces voluntary force after eccentric exercise but impaired neural drive to the muscle may also contribute. To determine whether the delayed-onset muscle soreness, which develops approximately 1 day after exercise, reduces voluntary activation and to identify the possible site for any reduction, voluntary activation of elbow flexor muscles was examined with both motor cortex and motor nerve stimulation. We measured maximal voluntary isometric torque (MVC), twitch torque, muscle soreness and voluntary activation in eight subjects before, immediately after, 2 h after, 1, 2, 4 and 8 days after eccentric exercise. Motor nerve stimulation and motor cortex stimulation were used to derive twitch torques and measures of voluntary activation. Eccentric exercise immediately reduced the MVC by 38 +/- 3% (mean +/- s.d., n = 8). The resting twitch produced by motor nerve stimulation fell by 82 +/- 6%, and the estimated resting twitch by cortical stimulation fell by 47 +/- 15%. While voluntary torque recovered after 8 days, both measures of the resting twitch remained depressed. Muscle tenderness occurred 1-2 days after exercise, and pain during contractions on days 1-4, but changes in voluntary activation did not follow this time course. Voluntary activation assessed with nerve stimulation fell 19 +/- 6% immediately after exercise but was not different from control values after 2 days. Voluntary activation assessed by motor cortex stimulation was unchanged by eccentric exercise. During MVCs, absolute increments in torque evoked by nerve and cortical stimulation behaved differently. Those to cortical stimulation decreased whereas those to nerve stimulation tended to increase. These findings suggest that reduced voluntary activation contributes to the early force loss after eccentric exercise, but that it is not due to muscle soreness. The impairment of voluntary activation to nerve stimulation but not motor cortical stimulation suggests that the activation

  20. Maximal force, voluntary activation and muscle soreness after eccentric damage to human elbow flexor muscles

    PubMed Central

    Prasartwuth, O; Taylor, JL; Gandevia, SC

    2005-01-01

    Muscle damage reduces voluntary force after eccentric exercise but impaired neural drive to the muscle may also contribute. To determine whether the delayed-onset muscle soreness, which develops ∼1 day after exercise, reduces voluntary activation and to identify the possible site for any reduction, voluntary activation of elbow flexor muscles was examined with both motor cortex and motor nerve stimulation. We measured maximal voluntary isometric torque (MVC), twitch torque, muscle soreness and voluntary activation in eight subjects before, immediately after, 2 h after, 1, 2, 4 and 8 days after eccentric exercise. Motor nerve stimulation and motor cortex stimulation were used to derive twitch torques and measures of voluntary activation. Eccentric exercise immediately reduced the MVC by 38 ± 3% (mean ±s.d., n = 8). The resting twitch produced by motor nerve stimulation fell by 82 ± 6%, and the estimated resting twitch by cortical stimulation fell by 47 ± 15%. While voluntary torque recovered after 8 days, both measures of the resting twitch remained depressed. Muscle tenderness occurred 1–2 days after exercise, and pain during contractions on days 1–4, but changes in voluntary activation did not follow this time course. Voluntary activation assessed with nerve stimulation fell 19 ± 6% immediately after exercise but was not different from control values after 2 days. Voluntary activation assessed by motor cortex stimulation was unchanged by eccentric exercise. During MVCs, absolute increments in torque evoked by nerve and cortical stimulation behaved differently. Those to cortical stimulation decreased whereas those to nerve stimulation tended to increase. These findings suggest that reduced voluntary activation contributes to the early force loss after eccentric exercise, but that it is not due to muscle soreness. The impairment of voluntary activation to nerve stimulation but not motor cortical stimulation suggests that the activation deficit lies in the

  1. Acoustic manipulation of active spherical carriers: Generation of negative radiation force

    NASA Astrophysics Data System (ADS)

    Rajabi, Majid; Mojahed, Alireza

    2016-09-01

    This paper examines theoretically a novel mechanism of generating negative (pulling) radiation force for acoustic manipulation of spherical carriers equipped with piezoelectric actuators in its inner surface. In this mechanism, the spherical particle is handled by common plane progressive monochromatic acoustic waves instead of zero-/higher- order Bessel beams or standing waves field. The handling strategy is based on applying a spatially uniform harmonic electrical voltage at the piezoelectric actuator with the same frequency of handling acoustic waves, in order to change the radiation force effect from repulsive (away from source) to attractive (toward source). This study may be considered as a start point for development of contact-free precise handling and entrapment technology of active carriers which are essential in many engineering and medicine applications.

  2. 16 CFR 1211.13 - Inherent force activated secondary door sensors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... sensors. 1211.13 Section 1211.13 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT... § 1211.13 Inherent force activated secondary door sensors. (a) Normal operation test. (1) A force activated door sensor of a door system installed according to the installation instructions shall...

  3. The Development of Air Force Undergraduate Space Training. LTTC Special Study.

    ERIC Educational Resources Information Center

    Levy, Michael H.

    This historical study traces the development of an undergraduate program at Lowry Technical Training Center (LTTC) situated in the Lowry Air Force Base, Colorado, to train Air Force officers and enlisted personnel for the space operations career field. The report begins in the 1950s when Air Force Systems Command examined the concept of a manned…

  4. Energy cost of isometric force production after active shortening in skinned muscle fibres.

    PubMed

    Joumaa, V; Fitzowich, A; Herzog, W

    2017-02-23

    The steady state isometric force after active shortening of a skeletal muscle is lower than the purely isometric force at the corresponding length. This property of skeletal muscle is known as force depression. The purpose of this study was to investigate whether the energy cost of force production at the steady state after active shortening was reduced compared to the energy cost of force production for a purely isometric contraction performed at the corresponding length (same length, same activation). Experiments were performed in skinned fibres isolated from rabbit psoas muscle. Skinned fibres were actively shortened from an average sarcomere length of 3.0 µm to an average sarcomere length of 2.4 µm. Purely isometric reference contractions were performed at an average sarcomere length of 2.4 µm. Simultaneously with the force measurements, the ATP cost was measured during the last 30 seconds of isometric contractions using an enzyme-coupled assay. Stiffness was calculated during a quick stretch-release cycle of 0.2% fibre length performed once the steady state had been reached after active shortening and during the purely isometric reference contractions. Force and stiffness following active shortening were decreased by 10.0±1.8% and 11.0±2.2%, respectively compared to the isometric reference contractions. Similarly, ATPase activity per second (not normalized to the force) showed a decrease of 15.6±3.0% in the force depressed state compared to the purely isometric reference state. However, ATPase activity per second per unit of force was similar for the isometric contractions following active shortening (28.7±2.4 mM/mN.s.mm(3)) and the corresponding purely isometric reference contraction (30.9±2.8 mM/mN.s.mm(3)). Furthermore, the reduction in absolute ATPase activity per second was significantly correlated with force depression and stiffness depression. These results are in accordance with the idea that force depression following active shortening is

  5. Depletion forces on circular and elliptical obstacles induced by active matter

    NASA Astrophysics Data System (ADS)

    Leite, L. R.; Lucena, D.; Potiguar, F. Q.; Ferreira, W. P.

    2016-12-01

    Depletion forces exerted by self-propelled particles on circular and elliptical passive objects are studied using numerical simulations. We show that a bath of active particles can induce repulsive and attractive forces which are sensitive to the shape and orientation of the passive objects (either horizontal or vertical ellipses). The resultant force on the passive objects due to the active particles is studied as a function of the shape and orientation of the passive objects, magnitude of the angular noise, and distance between the passive objects. By increasing the distance between obstacles the magnitude of the repulsive depletion force increases, as long as such a distance is less than one active particle diameter. For longer distances, the magnitude of the force always decreases with increasing distance. We also found that attractive forces may arise for vertical ellipses at high enough area fraction.

  6. Reduced Maximal Force during Acute Anterior Knee Pain Is Associated with Deficits in Voluntary Muscle Activation

    PubMed Central

    Salomoni, Sauro; Tucker, Kylie; Hug, François; McPhee, Megan; Hodges, Paul

    2016-01-01

    Although maximal voluntary contraction (MVC) force is reduced during pain, studies using interpolated twitch show no consistent reduction of voluntary muscle drive. The present study aimed to test if the reduction in MVC force during acute experimental pain could be explained by increased activation of antagonist muscles, weak voluntary activation at baseline, or changes in force direction. Twenty-two healthy volunteers performed maximal voluntary isometric knee extensions before, during, and after the effects of hypertonic (pain) and isotonic (control) saline injections into the infrapatellar fat pad. The MVC force, voluntary activation, electromyographic (EMG) activity of agonist, antagonist, and auxiliary (hip) muscles, and pain cognition and anxiety scores were recorded. MVC force was 9.3% lower during pain than baseline (p < 0.001), but there was no systematic change in voluntary activation. Reduced MVC force during pain was variable between participants (SD: 14%), and was correlated with reduced voluntary activation (r = 0.90), baseline voluntary activation (r = − 0.62), and reduced EMG amplitude of agonist and antagonist muscles (all r > 0.52), but not with changes in force direction, pain or anxiety scores. Hence, reduced MVC force during acute pain was mainly explained by deficits in maximal voluntary drive. PMID:27559737

  7. Muscular activity and physical interaction forces during lower limb exoskeleton use.

    PubMed

    Wilcox, Matthew; Rathore, Ashish; Morgado Ramirez, Dafne Zuleima; Loureiro, Rui C V; Carlson, Tom

    2016-12-01

    Spinal cord injury (SCI) typically manifests with a loss of sensorimotor control of the lower limbs. In order to overcome some of the disadvantages of chronic wheelchair use by such patients, robotic exoskeletons are an emerging technology that has the potential to transform the lives of patients. However, there are a number of points of contact between the robot and the user, which lead to interaction forces. In a recent study, the authors have shown that peak interaction forces are particularly prominent at the anterior aspect of the right leg. This study uses a similar experimental protocol with additional electromyography (EMG) analysis to examine whether such interaction forces are due to the muscular activity of the participant or the movement of the exoskeleton itself. Interestingly, the authors found that peak forces preceded peak EMG activity. This study did not find a significant correlation between EMG activity and force data, which would indicate that the interaction forces can largely be attributed to the movement of the exoskeleton itself. However, we also report significantly higher correlation coefficients in muscle/force pairs located at the anterior aspect of the right leg. In their previous research, the authors have shown peak interaction forces at the same locations, which suggests that muscular activity of the participant makes a more significant contribution to the interaction forces at these locations. The findings of this study are of significance for incomplete SCI patients, for whom EMG activity may provide an important input to an intuitive control schema.

  8. U.S. Strategic Nuclear Forces: Background, Developments, and Issues

    DTIC Science & Technology

    2014-09-05

    deploy the Minuteman III ICBM, with 3 warheads on each missile, in 1970, and the Poseidon SLBM, which could carry 10 warheads on each missile, in...missiles, for a total force of 2,450 warheads on 1,000 missiles. The submarine force included Poseidon submarines with Poseidon C-3 and Trident I (C...www.nrdc.org/nuclear/nudb/datab1.asp. 13 GlobalSecurity.org LGM Minuteman III History and Poseidon C-3 History. http://www.globalsecurity.org/wmd

  9. Active Design Method for the Static Characteristics of a Piezoelectric Six-Axis Force/Torque Sensor

    PubMed Central

    Liu, Jun; Li, Min; Qin, Lan; Liu, Jingcheng

    2014-01-01

    To address the bottleneck issues of an elastic-style six-axis force/torque sensor (six-axis force sensor), this work proposes a no-elastic piezoelectric six-axis force sensor. The operating principle of the piezoelectric six-axis force sensor is analyzed, and a structural model is constructed. The static-active design theory of the piezoelectric six-axis force sensor is established, including a static analytical/mathematical model and numerical simulation model (finite element model). A piezoelectric six-axis force sensor experimental prototype is developed according to the analytical mathematical model and numerical simulation model, and selected static characteristic parameters (including sensitivity, isotropic degree and cross-coupling) are tested using this model with three approaches. The measured results are in agreement with the analytical results from the static-active design method. Therefore, this study has successfully established a foundation for further research into the piezoelectric multi-axis force sensor and an overall design approach based on static characteristics. PMID:24451460

  10. Mechanosensitive Channel Activation by Diffusio-Osmotic Force

    NASA Astrophysics Data System (ADS)

    Bonthuis, Douwe Jan; Golestanian, Ramin

    2014-10-01

    For ion channel gating, the appearance of two distinct conformational states and the discrete transitions between them are essential, and therefore of crucial importance to all living organisms. We show that the physical interplay between two structural elements that are commonly present in bacterial mechanosensitive channels—namely, a charged vestibule and a hydrophobic constriction—creates two distinct conformational states, open and closed, as well as the gating between them. We solve the nonequilibrium Stokes-Poisson-Nernst-Planck equations, extended to include a molecular potential of mean force, and show that a first order transition between the closed and open states arises naturally from the diffusio-osmotic stress caused by the ions and the water inside the channel and the elastic restoring force from the membrane.

  11. Mechanosensitive channel activation by diffusio-osmotic force.

    PubMed

    Bonthuis, Douwe Jan; Golestanian, Ramin

    2014-10-03

    For ion channel gating, the appearance of two distinct conformational states and the discrete transitions between them are essential, and therefore of crucial importance to all living organisms. We show that the physical interplay between two structural elements that are commonly present in bacterial mechanosensitive channels--namely, a charged vestibule and a hydrophobic constriction--creates two distinct conformational states, open and closed, as well as the gating between them. We solve the nonequilibrium Stokes-Poisson-Nernst-Planck equations, extended to include a molecular potential of mean force, and show that a first order transition between the closed and open states arises naturally from the diffusio-osmotic stress caused by the ions and the water inside the channel and the elastic restoring force from the membrane.

  12. Morphological Transformation and Force Generation of Active Cytoskeletal Networks

    PubMed Central

    Maruri, Daniel; Kamm, Roger D.

    2017-01-01

    Cells assemble numerous types of actomyosin bundles that generate contractile forces for biological processes, such as cytokinesis and cell migration. One example of contractile bundles is a transverse arc that forms via actomyosin-driven condensation of actin filaments in the lamellipodia of migrating cells and exerts significant forces on the surrounding environments. Structural reorganization of a network into a bundle facilitated by actomyosin contractility is a physiologically relevant and biophysically interesting process. Nevertheless, it remains elusive how actin filaments are reoriented, buckled, and bundled as well as undergo tension buildup during the structural reorganization. In this study, using an agent-based computational model, we demonstrated how the interplay between the density of myosin motors and cross-linking proteins and the rigidity, initial orientation, and turnover of actin filaments regulates the morphological transformation of a cross-linked actomyosin network into a bundle and the buildup of tension occurring during the transformation. PMID:28114384

  13. Developing accurate molecular mechanics force fields for conjugated molecular systems.

    PubMed

    Do, Hainam; Troisi, Alessandro

    2015-10-14

    A rapid method to parameterize the intramolecular component of classical force fields for complex conjugated molecules is proposed. The method is based on a procedure of force matching with a reference electronic structure calculation. It is particularly suitable for those applications where molecular dynamics simulations are used to generate structures that are therefore analysed by electronic structure methods, because it is possible to build force fields that are consistent with electronic structure calculations that follow classical simulations. Such applications are commonly encountered in organic electronics, spectroscopy of complex systems and photobiology (e.g. photosynthetic systems). We illustrate the method by parameterizing the force fields of a molecule used in molecular semiconductors (2,2-dicyanovinyl-capped S,N-heteropentacene or DCV-SN5), a polymeric semiconductor (thieno[3,2-b]thiophene-diketopyrrolopyrrole TT-DPP) and a chromophore embedded in a protein environment (15,16-dihydrobiliverdin or DBV) where several hundreds of parameters need to be optimized in parallel.

  14. The Strategic Development of the Trinidad and Tobago Defence Force

    DTIC Science & Technology

    2009-06-12

    and ecommerce . In combination, these driving forces of change led to an explosion in world trade, an exponential increase in business ...and Tobago Defence Force‘s approach to organization strategy. In defining this term, the author slightly amends Thompson and Strickland‘s business ...extreme competition and intense rivalry especially between American and Japanese businesses . 15 After many decades of domination, American businesses

  15. A Hands-On Activity to Build Mastery of Intermolecular Forces and Its Impacts on Student Learning

    ERIC Educational Resources Information Center

    Bruck, Laura B.

    2016-01-01

    The intermolecular forces activity presented in this article is designed to foster concept-building through students' use of concrete, manipulative objects, and it was developed to be pedagogically sound. Data analysis via pre- and posttesting and subsequent exam questions indicated that students who had the opportunity to participate in the…

  16. Force-Induced H2S by PDLSCs Modifies Osteoclastic Activity during Tooth Movement.

    PubMed

    Liu, F; Wen, F; He, D; Liu, D; Yang, R; Wang, X; Yan, Y; Liu, Y; Kou, X; Zhou, Y

    2017-02-01

    Hydrogen sulfide (H2S), a gasotransmitter, has been recently linked to mesenchymal stem cell (MSC) function and bone homeostasis. Periodontal ligament stem cells (PDLSCs) are the main MSCs in PDL, which respond to mechanical force to induce physiological activities during orthodontic tooth movement (OTM). However, it is unknown whether mechanical force might induce endogenous H2S production by PDLSCs to regulate alveolar bone homeostasis. Here, we used a mouse OTM model to demonstrate that orthodontic force-induced endogenous H2S production in PDL tissue was associated with macrophage accumulation and osteoclastic activity in alveolar bone. Then, we showed that mechanical force application induced cystathionine β-synthase (CBS) expression and endogenous H2S production by PDLSCs. Moreover, blocking endogenous H2S or systemically increasing H2S levels could decrease or enhance force-induced osteoclastic activities to control tooth movement. We further revealed how force-induced H2S production by PDLSCs contributed to the secretion of monocyte chemoattractant protein-1 (MCP-1) and the expression of receptor activator of nuclear factor-κB ligand/osteoprotegerin (RANKL/OPG) system by PDLSCs. The secretion and expression of these factors controlled macrophage migration and osteoclast differentiation. This study demonstrated that PDLSCs produced H2S to respond to and transduce force signals. Force-induced gasotransmitter H2S production in PDLSCs therefore regulated osteoclastic activities in alveolar bone and controlled the OTM process through the MCP-1 secretion and RANKL/OPG system.

  17. Development of a mechanistic model for forced convection subcooled boiling

    NASA Astrophysics Data System (ADS)

    Shaver, Dillon R.

    The focus of this work is on the formulation, implementation, and testing of a mechanistic model of subcooled boiling. Subcooled boiling is the process of vapor generation on a heated wall when the bulk liquid temperature is still below saturation. This is part of a larger effort by the US DoE's CASL project to apply advanced computational tools to the simulation of light water reactors. To support this effort, the formulation of the dispersed field model is described and a complete model of interfacial forces is formulated. The model has been implemented in the NPHASE-CMFD computer code with a K-epsilon model of turbulence. The interfacial force models are built on extensive work by other authors, and include novel formulations of the turbulent dispersion and lift forces. The complete model of interfacial forces is compared to experiments for adiabatic bubbly flows, including both steady-state and unsteady conditions. The same model is then applied to a transient gas/liquid flow in a complex geometry of fuel channels in a sodium fast reactor. Building on the foundation of the interfacial force model, a mechanistic model of forced-convection subcooled boiling is proposed. This model uses the heat flux partitioning concept and accounts for condensation of bubbles attached to the wall. This allows the model to capture the enhanced heat transfer associated with boiling before the point of net generation of vapor, a phenomenon consistent with existing experimental observations. The model is compared to four different experiments encompassing flows of light water, heavy water, and R12 at different pressures, in cylindrical channels, an internally heated annulus, and a rectangular channel. The experimental data includes axial and radial profiles of both liquid temperature and vapor volume fraction, and the agreement can be considered quite good. The complete model is then applied to simulations of subcooled boiling in nuclear reactor subchannels consistent with the

  18. Effect of stretching on agonist-antagonist muscle activity and muscle force output during single and multiple joint isometric contractions.

    PubMed

    McBride, J M; Deane, R; Nimphius, S

    2007-02-01

    Eight moderately active male subjects where tested for peak force in an isometric knee extension test and peak force and rate of force development in an isometric squat test. Both tests where performed at a 100 degrees knee angle and average integrated electromyography (IEMG) was measured from the vastus medialis (VM), vastus lateralis (VL) and biceps femoris (BF) muscles. Subjects performed the two conditions, stretching (S) or control (C) in a randomized order. Subjects where tested for baseline strength measures in both the isometric knee extension and isometric squat and then either stretched or sat quietly for 10 min. Following S or C subjects where then tested at six time points. Following S peak force in the isometric knee extension was significantly (P < or = 0.05) less than C at 1, 2, 8 and 16 min post. No significant difference in peak force was found between S and C in the isometric squat. However, following S the rate of force development in the isometric squat was significantly less than C at immediately post. No significant differences where observed in IEMG of the VM or VL between S and C in either the isometric knee extension or isometric squat. However, IEMG significantly decreased in the BF at 1 min post after S in comparison with C in both the isometric knee extension and isometric squat. Stretching appears to decrease muscle force output in a single joint isometric contraction and rate of force development in a multiple joint isometric contraction. Possible changes in agonist-antagonist muscle activity patterns need to be further examined.

  19. Validation and Verification of the Operational Land Analysis Activities at the Air Force Weather Agency

    NASA Astrophysics Data System (ADS)

    Shaw, M.; Kumar, S.; Peters-Lidard, C. D.; Cetola, J.

    2011-12-01

    The importance of operational benchmarking and uncertainty characterization of land surface modeling can be clear upon considering the wide range of performance characteristics of numerical land surface models realizable through various combinations of factors. Such factors might include model physics and numerics, resolution, and forcing datasets used in operational implementation versus those that might have been involved in any prior development benchmarking. Of course, decisions concerning operational implementation may be better informed through more effective benchmarking of performance under various blends of such aforementioned operational factors. To facilitate this and other needs for land analysis activities at the Air Force Weather Agency (AFWA), the Model Evaluation Toolkit (MET) - a joint product of the National Center for Atmospheric Research Developmental Testbed Center (NCAR DTC), AFWA, and the user community - and the land information system (LIS) Verification Toolkit (LVT) - developed at the Goddard Space Flight Center (GSFC) - have been adapted to the operational benchmarking needs of AFWA's land characterization activities in order to compare the performance of new land modeling and related activities with that of previous activities as well as observational or analyzed datasets. In this talk, three examples of adaptations of MET and LVT to evaluation of LIS-related operations at AFWA will be presented. One example will include comparisons of new surface rainfall analysis capabilities, towards forcing of AFWA's LIS, with previous capabilities. Comparisons will be relative to retrieval-, model-, and measurement-based precipitation fields. Results generated via MET's grid-stat, neighborhood, wavelet, and object based evaluation (MODE) utilities adapted to AFWA's needs will be discussed. This example will be framed in the context of better informing optimal blends of land surface model (LSM) forcing data sources - namely precipitation data- under

  20. Environmental Assessment: Installation Development at Sheppard Air Force Base, Texas

    DTIC Science & Technology

    2007-05-01

    Branch) US Fish and Wildlife Service Carter, Patricia (NEPA Program Coordinator) 6.2 STATE AGENCIES Federal Emergency Management Agency Fairley ...FORCE’ AIR EDU.CATION AND TRAINING COMMAND 82 CES/CEVX 231 9th Avenue Stop 201 Sheppard AFB TX 76311-3333 Donald Fairley Environmental Specialist...TRAINING COMMAND March 7, 2007 82 CES/CEVX 231 9th Avenue Stop 201 Sheppard AFB TX 76311-3333 Donald Fairley Environmental

  1. Spiritual Development for Strategic Leadership in the Air Force

    DTIC Science & Technology

    2010-03-01

    demonstrated behavior harmful to the profession of arms. Examples of military members’ moral deficiencies continue to make headlines across the... behavior not consistent with Air Force values. 3 Dictionary.com defines conscience as “the inner sense of what is right or wrong in one’s conduct...16 Similarly, Webster defines moral as “of or relating to principles of right and wrong in behavior …expressing or teaching a conception of right

  2. Accurate Force Field Development for Modeling Conjugated Polymers.

    PubMed

    DuBay, Kateri H; Hall, Michelle Lynn; Hughes, Thomas F; Wu, Chuanjie; Reichman, David R; Friesner, Richard A

    2012-11-13

    The modeling of the conformational properties of conjugated polymers entails a unique challenge for classical force fields. Conjugation imposes strong constraints upon bond rotation. Planar configurations are favored, but the concomitantly shortened bond lengths result in moieties being brought into closer proximity than usual. The ensuing steric repulsions are particularly severe in the presence of side chains, straining angles, and stretching bonds to a degree infrequently found in nonconjugated systems. We herein demonstrate the resulting inaccuracies by comparing the LMP2-calculated inter-ring torsion potentials for a series of substituted stilbenes and bithiophenes to those calculated using standard classical force fields. We then implement adjustments to the OPLS-2005 force field in order to improve its ability to model such systems. Finally, we show the impact of these changes on the dihedral angle distributions, persistence lengths, and conjugation length distributions observed during molecular dynamics simulations of poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) and poly 3-hexylthiophene (P3HT), two of the most widely used conjugated polymers.

  3. Development of a synthetic gene network to modulate gene expression by mechanical forces

    PubMed Central

    Kis, Zoltán; Rodin, Tania; Zafar, Asma; Lai, Zhangxing; Freke, Grace; Fleck, Oliver; Del Rio Hernandez, Armando; Towhidi, Leila; Pedrigi, Ryan M.; Homma, Takayuki; Krams, Rob

    2016-01-01

    The majority of (mammalian) cells in our body are sensitive to mechanical forces, but little work has been done to develop assays to monitor mechanosensor activity. Furthermore, it is currently impossible to use mechanosensor activity to drive gene expression. To address these needs, we developed the first mammalian mechanosensitive synthetic gene network to monitor endothelial cell shear stress levels and directly modulate expression of an atheroprotective transcription factor by shear stress. The technique is highly modular, easily scalable and allows graded control of gene expression by mechanical stimuli in hard-to-transfect mammalian cells. We call this new approach mechanosyngenetics. To insert the gene network into a high proportion of cells, a hybrid transfection procedure was developed that involves electroporation, plasmids replication in mammalian cells, mammalian antibiotic selection, a second electroporation and gene network activation. This procedure takes 1 week and yielded over 60% of cells with a functional gene network. To test gene network functionality, we developed a flow setup that exposes cells to linearly increasing shear stress along the length of the flow channel floor. Activation of the gene network varied logarithmically as a function of shear stress magnitude. PMID:27404994

  4. Rupture Forces among Human Blood Platelets at different Degrees of Activation

    PubMed Central

    Nguyen, Thi-Huong; Palankar, Raghavendra; Bui, Van-Chien; Medvedev, Nikolay; Greinacher, Andreas; Delcea, Mihaela

    2016-01-01

    Little is known about mechanics underlying the interaction among platelets during activation and aggregation. Although the strength of a blood thrombus has likely major biological importance, no previous study has measured directly the adhesion forces of single platelet-platelet interaction at different activation states. Here, we filled this void first, by minimizing surface mediated platelet-activation and second, by generating a strong adhesion force between a single platelet and an AFM cantilever, preventing early platelet detachment. We applied our setup to measure rupture forces between two platelets using different platelet activation states, and blockade of platelet receptors. The rupture force was found to increase proportionally to the degree of platelet activation, but reduced with blockade of specific platelet receptors. Quantification of single platelet-platelet interaction provides major perspectives for testing and improving biocompatibility of new materials; quantifying the effect of drugs on platelet function; and assessing the mechanical characteristics of acquired/inherited platelet defects. PMID:27146004

  5. Effects of Sled Towing on Peak Force, the Rate of Force Development and Sprint Performance During the Acceleration Phase.

    PubMed

    Martínez-Valencia, María Asunción; Romero-Arenas, Salvador; Elvira, José L L; González-Ravé, José María; Navarro-Valdivielso, Fernando; Alcaraz, Pedro E

    2015-06-27

    Resisted sprint training is believed to increase strength specific to sprinting. Therefore, the knowledge of force output in these tasks is essential. The aim of this study was to analyze the effect of sled towing (10%, 15% and 20% of body mass (Bm)) on sprint performance and force production during the acceleration phase. Twenty-three young experienced sprinters (17 men and 6 women; men = 17.9 ± 3.3 years, 1.79 ± 0.06 m and 69.4 ± 6.1 kg; women = 17.2 ± 1.7 years, 1.65 ± 0.04 m and 56.6 ± 2.3 kg) performed four 30 m sprints from a crouch start. Sprint times in 20 and 30 m sprint, peak force (Fpeak), a peak rate of force development (RFDpeak) and time to RFD (TRFD) in first step were recorded. Repeated-measures ANOVA showed significant increases (p ≤ 0.001) in sprint times (20 and 30 m sprint) for each resisted condition as compared to the unloaded condition. The RFDpeak increased significantly when a load increased (3129.4 ± 894.6 N·s-1, p ≤ 0.05 and 3892.4 ± 1377.9 N·s-1, p ≤ 0.01). Otherwise, no significant increases were found in Fpeak and TRFD. The RFD determines the force that can be generated in the early phase of muscle contraction, and it has been considered a factor that influences performance of force-velocity tasks. The use of a load up to 20% Bm might provide a training stimulus in young sprinters to improve the RFDpeak during the sprint start, and thus, early acceleration.

  6. Effects of Sled Towing on Peak Force, the Rate of Force Development and Sprint Performance During the Acceleration Phase

    PubMed Central

    Martínez-Valencia, María Asunción; Romero-Arenas, Salvador; Elvira, José L.L.; González-Ravé, José María; Navarro-Valdivielso, Fernando; Alcaraz, Pedro E.

    2015-01-01

    Resisted sprint training is believed to increase strength specific to sprinting. Therefore, the knowledge of force output in these tasks is essential. The aim of this study was to analyze the effect of sled towing (10%, 15% and 20% of body mass (Bm)) on sprint performance and force production during the acceleration phase. Twenty-three young experienced sprinters (17 men and 6 women; men = 17.9 ± 3.3 years, 1.79 ± 0.06 m and 69.4 ± 6.1 kg; women = 17.2 ± 1.7 years, 1.65 ± 0.04 m and 56.6 ± 2.3 kg) performed four 30 m sprints from a crouch start. Sprint times in 20 and 30 m sprint, peak force (Fpeak), a peak rate of force development (RFDpeak) and time to RFD (TRFD) in first step were recorded. Repeated-measures ANOVA showed significant increases (p ≤ 0.001) in sprint times (20 and 30 m sprint) for each resisted condition as compared to the unloaded condition. The RFDpeak increased significantly when a load increased (3129.4 ± 894.6 N·s−1, p ≤ 0.05 and 3892.4 ± 1377.9 N·s−1, p ≤ 0.01). Otherwise, no significant increases were found in Fpeak and TRFD. The RFD determines the force that can be generated in the early phase of muscle contraction, and it has been considered a factor that influences performance of force-velocity tasks. The use of a load up to 20% Bm might provide a training stimulus in young sprinters to improve the RFDpeak during the sprint start, and thus, early acceleration. PMID:26240657

  7. Kosovo Armed Forces Development; Achieving NATO Non-Article 5 Crisis Response Operations Interoperability

    DTIC Science & Technology

    2014-12-12

    KOSOVO ARMED FORCES DEVELOPMENT; ACHIEVING NATO NON-ARTICLE 5 CRISIS RESPONSE OPERATIONS INTEROPERABILITY A thesis presented...Achieving NATO Non- Article 5 Crisis Response Operations Interoperability 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...interoperable and effective in NATO-led Crisis Response Operations. Therefore, this study focuses in examining current Kosovo Armed Forces development program

  8. 78 FR 7849 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-04

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Interagency Task Force on Veterans Small Business Development AGENCY: U.S. Small Business... Force on Veterans Small Business Development. The meeting will be open to the public. DATES:...

  9. Introducing a new semi-active engine mount using force controlled variable stiffness

    NASA Astrophysics Data System (ADS)

    Azadi, Mojtaba; Behzadipour, Saeed; Faulkner, Gary

    2013-05-01

    This work introduces a new concept in designing semi-active engine mounts. Engine mounts are under continuous development to provide better and more cost-effective engine vibration control. Passive engine mounts do not provide satisfactory solution. Available semi-active and active mounts provide better solutions but they are more complex and expensive. The variable stiffness engine mount (VSEM) is a semi-active engine mount with a simple ON-OFF control strategy. However, unlike available semi-active engine mounts that work based on damping change, the VSEM works based on the static stiffness change by using a new fast response force controlled variable spring. The VSEM is an improved version of the vibration mount introduced by the authors in their previous work. The results showed significant performance improvements over a passive rubber mount. The VSEM also provides better vibration control than a hydromount at idle speed. Low hysteresis and the ability to be modelled by a linear model in low-frequency are the advantages of the VSEM over the vibration isolator introduced earlier and available hydromounts. These specifications facilitate the use of VSEM in the automotive industry, however, further evaluation and developments are needed for this purpose.

  10. Increase in rate of force development with skin cooling during isometric knee extension.

    PubMed

    Shimose, Ryota; Ushigome, Nobuyuki; Tadano, Chigaya; Sugawara, Hitoshi; Yona, Masae; Matsunaga, Atsuhiko; Muro, Masuo

    2014-12-01

    Rate of force development (RFD) plays an important role when performing rapid and forceful movements. Cold-induced afferent input with transient skin cooling (SC) can modulate neural drive. However, the relationship between RFD and SC is unknown. The purpose of this study was to investigate whether SC increases RFD during isometric knee extension. Fifteen young healthy men (25 ± 8 yrs old) contracted their quadriceps muscle as fast and forcefully as possible with or without SC. Skin cooling was administered to the front of the thigh. Torque and electromyographic activity were measured simultaneously. Peak torque was not affected by SC. Skin cooling induced a significant increase in RFD at the phase 0-30 and 0-50 ms. The root mean square of the electromyography of vastus medialis, rectus femoris and vastus lateralis at the phases 0-30-50-100 ms increased significantly or tended to increase with SC. These results suggest that SC may increase neural drive and improve RFD in the very early phases of contraction.

  11. Within- and between-session reliability of power, force, and rate of force development during the power clean.

    PubMed

    Comfort, Paul

    2013-05-01

    Although there has been extensive research regarding the power clean, its application to sports performance, and use as a measure of assessing changes in performance, no research has determined the reliability assessing the kinetics of the power clean across testing session. The aim of this study was to determine the within- and between-session reliability of kinetic variables during the power clean. Twelve professional rugby league players (age 24.5 ± 2.1 years; height 182.86 ± 6.97 cm; body mass 92.85 ± 5.67 kg; 1 repetition maximum [1RM] power clean 102.50 ± 10.35 kg) performed 3 sets of 3 repetitions of power cleans at 70% of their 1RM, while standing on a force plate, to determine within-session reliability and repeated on 3 separate occasions to determine reliability between sessions. Intraclass correlation coefficients revealed a high reliability within- (r ≥ 0.969) and between-sessions (r ≥ 0.988). Repeated-measures analysis of variance showed no significant difference (p > 0.05) in peak vertical ground reaction force, rate of force development, and peak power between sessions, with small standard error of the measurements and smallest detectable differences for each kinetic variable (3.13 and 8.68 N; 84.39 and 233.93 N·s; 24.54 and 68.01 W, respectively). Therefore, to identify a meaningful change in performance, the strength and conditioning coach should look for a change in peak force ≥8.68 N, rate of force development ≥24.54 N·s, and a change in peak power ≥68.01 W to signify an adaptive response to training, which is greater than the variance between sessions, in trained athletes proficient at performing the power clean.

  12. The Development of a Scenario Set for Departmental Force Planning

    DTIC Science & Technology

    1998-11-01

    scenarios minimum aux fins de planification des forces du ministere. En reponse ace besoin, le directeur- analyse de defense (DAD) a parraine...document le Livre blanc sur la defense 1994, tandis que le document Guide de Planification de la Defense. 1997 fournissait un complement...Sufficiency in Raw Materials C3 .3 .4.1.4 Self-Sufficiency in Finished Goods C3 .3 .4.1.5 Self-Sufficiency in Machinery C3.3.4.2 Fiscal Position C3 .3

  13. The forces behind the words: development of the kinetic pen.

    PubMed

    Hooke, Alexander W; Park, Jaebum; Shim, Jae Kun

    2008-01-01

    This paper describes the creation of a Kinetic Pen capable of measuring the six-component force and torque that each of four individual contacts applies to the pen during writing. This was done by staggering the mounting of the four sensors along the long axis of the pen and having an extended arm run from the sensor to the grip site, preventing a clustering of the sensors where the digit tips meet while grasping. The implications of this tool allow handwriting studies to be expanded from two-dimensional pen-tip kinematics to three-dimensional dynamics at each contact point between the hand and pen.

  14. U.S. Strategic Nuclear Forces: Background, Developments, and Issues

    DTIC Science & Technology

    2014-05-15

    missile, in 1970, and the Poseidon SLBM, which could carry 10 warheads on each missile, in 1971.13 The increase in warheads in the mid-1980s reflects the...missiles. The submarine force included Poseidon submarines with Poseidon C-3 and Trident I (C-4) missiles, and the Ohio-class Trident submarines with...LGM Minuteman III History and Poseidon C-3 History. http://www.globalsecurity.org/wmd/ systems/lgm-30_3-hist.htm and http://www.globalsecurity.org/wmd

  15. Trunk muscle activation and associated lumbar spine joint shear forces under different levels of external forward force applied to the trunk.

    PubMed

    Kingma, Idsart; Staudenmann, Didier; van Dieën, Jaap H

    2007-02-01

    High anterior intervertebral shear loads could cause low back injuries and therefore the neuromuscular system may actively counteract these forces. This study investigated whether, under constant moment loading relative to L3L4, an increased externally applied forward force on the trunk results in a shift in muscle activation towards the use of muscles with more backward directed lines of action, thereby reducing the increase in total joint shear force. Twelve participants isometrically resisted forward forces, applied at several locations on the trunk, while moments were held constant relative to L3L4. Surface EMG and lumbar curvature were measured, and an EMG-driven muscle model was used to calculate compression and shear forces at all lumbar intervertebral joints. Larger externally applied forward forces resulted in a flattening of the lumbar lordosis and a slightly more backward directed muscle force. Furthermore, the overall muscle activation increased. At the T12L1 to L3L4 joint, resulting joint shear forces remained small (less than 200N) because the average muscle force pulled backward relative to those joints. However, at the L5S1 joint the average muscle force pulled the trunk forward so that the increase in muscle force with increasing externally applied forward force caused a further rise in shear force (by 102.1N, SD=104.0N), resulting in a joint shear force of 1080.1N (SD=150.4N) at 50Nm moment loading. It is concluded that the response of the neuromuscular system to shear force challenges tends to increase rather than reduce the shear loading at the lumbar joint that is subjected to the highest shear forces.

  16. Subthalamic nucleus local field potential activity helps encode motor effort rather than force in parkinsonism.

    PubMed

    Tan, Huiling; Pogosyan, Alek; Ashkan, Keyoumars; Cheeran, Binith; FitzGerald, James J; Green, Alexander L; Aziz, Tipu; Foltynie, Thomas; Limousin, Patricia; Zrinzo, Ludvic; Brown, Peter

    2015-04-15

    Local field potential (LFP) recordings from patients with deep brain stimulation electrodes in the basal ganglia have suggested that frequency-specific activities correlate with force or effort, but previous studies have not been able to disambiguate the two. Here, we dissociated effort from actual force generated by contrasting the force generation of different fingers while recording LFP activity from the subthalamic nucleus (STN) in patients with Parkinson's disease who had undergone functional surgery. Patients were studied while on their normal dopaminergic medication. We investigated the relationship between frequency-specific oscillatory activity in the STN and voluntary flexion of either the index or little finger at different effort levels. At each tested effort level (10%, 25%, and 40% of the maximal voluntary contraction force of each individual finger), the index finger generated larger force than the little finger. Movement-related suppression of beta-band power in the STN LFP was significantly modulated by effort, but not by which finger was used, suggesting that the beta suppression in the STN LFP during sustained contraction serves as a proxy for effort. The absolute force scaled with beta power suppression, but with the scaling determined by the maximal voluntary contraction force of the motor effector. Our results argue against the hypothesis that the basal ganglia are directly involved in the parameterization of force during movement and support a role of the STN in the control of motor effort to be attributed to a response.

  17. [Medical support of the Armed Forces of the Russian Federation: results of activity and tasks for 2016].

    PubMed

    Fisun, A Ya

    2016-01-01

    The author gives an analysis of activity of the medical service of the Armed Forces in 2015 concerning development of normative legal basis for the military health care, improvement of the level of operational and mobilization readiness of subunits of army group, and military-medical institutions, improvement of effectiveness of treatment and evacuation measures, health resort treatment, medical stuff training optimization, sanitary-and-epidemiologic support, material and technical support improvement, adoption of advanced scientific achievements focusing on medical care delivery to army group, active development and increase in medical information systems, telehealth. system. The author gives data characterizing state and level of development of medical service of the Armed Forces and its dynamics. Main tasks and parameters of development of the service in 2016 and up to 2020 are formulated.

  18. 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.

  19. Residual force depression in single sarcomeres is abolished by MgADP-induced activation.

    PubMed

    Trecarten, Neal; Minozzo, Fabio C; Leite, Felipe S; Rassier, Dilson E

    2015-06-03

    The mechanisms behind the shortening-induced force depression commonly observed in skeletal muscles remain unclear, but have been associated with sarcomere length non-uniformity and/or crossbridge inhibition. The purpose of this study was twofold: (i) to evaluate if force depression is present in isolated single sarcomeres, a preparation that eliminates sarcomere length non-uniformities and (ii) to evaluate if force depression is inhibited when single sarcomeres are activated with MgADP, which biases crossbridges into a strongly-bound state. Single sarcomeres (n = 16) were isolated from rabbit psoas myofibrils using two micro-needles (one compliant, one rigid), piercing the sarcomere externally adjacent to the Z-lines. The sarcomeres were contracted isometrically and subsequently shortened, in both Ca(2+)- and MgADP-activating solutions. Shortening in Ca(2+)-activated samples resulted in a 27.44 ± 9.04% force depression when compared to isometric contractions produced at similar final sarcomere lengths (P < 0.001). There was no force depression in MgADP-activated sarcomeres (force depression = -1.79 ± 9.69%, P =  0.435). These results suggest that force depression is a sarcomeric property, and that is associated with an inhibition of myosin-actin interactions.

  20. Women's labour force participation and socioeconomic development: influences of local context and individual characteristics in Brazil.

    PubMed

    Evans, M D; Saraiva, H U

    1993-03-01

    We address several key hypotheses about the effects of socioeconomic development on women's labour force participation during the transition from agriculture to industrialism. To this end, we explore differences in women's labour force participation in Brazil by education, marital status, age, and urban or rural residence. We also show how socioeconomic development affects the overall level of women's participation and the differentials by education, etc. Our data are drawn from a large 1973 PNAD (Pequisa Nacional por Amostra de Domicilos) survey conducted by the Brazilian census bureau. Socioeconomic development in different parts of Brazil ranges from pre-industrial agriculture to heavy industry. Using logistic regression, we show that the general level of women's labour force participation does not change with the level of development. Highly educated women are much more likely than the less educated to be in the labour force (net of other influences); this difference is substantially greater than in post-industrial societies. Somewhat surprisingly, the influence of education is the same across the range of development levels in Brazil. Single women are more likely to be in the labour force than married women, and the difference grows during development. Age has a curvilinear relationship to labour force participation, and the old are much less likely to participate in more developed places. Rural women are slightly more likely to be in the labour force at all levels of development.

  1. Musculoskeletal modelling of muscle activation and applied external forces for the correction of scoliosis

    PubMed Central

    2014-01-01

    Background This study uses biomechanical modelling and computational optimization to investigate muscle activation in combination with applied external forces as a treatment for scoliosis. Bracing, which incorporates applied external forces, is the most popular non surgical treatment for scoliosis. Non surgical treatments which make use of muscle activation include electrical stimulation, postural control, and therapeutic exercises. Electrical stimulation has been largely dismissed as a viable treatment for scoliosis, although previous studies have suggested that it can potentially deliver similarly effective corrective forces to the spine as bracing. Methods The potential of muscle activation for scoliosis correction was investigated over different curvatures both with and without the addition of externally applied forces. The five King’s classifications of scoliosis were investigated over a range of Cobb angles. A biomechanical model of the spine was used to represent various scoliotic curvatures. Optimization was applied to the model to reduce the curves using combinations of both deep and superficial muscle activation and applied external forces. Results Simulating applied external forces in combination with muscle activation at low Cobb angles (< 20 degrees) over the 5 King’s classifications, it was possible to reduce the magnitude of the curve by up to 85% for classification 4, 75% for classifications 3 and 5, 65% for classification 2, and 60% for classification 1. The reduction in curvature was less at larger Cobb angles. For King’s classifications 1 and 2, the serratus, latissimus dorsi, and trapezius muscles were consistently recruited by the optimization algorithm for activation across all Cobb angles. When muscle activation and external forces were applied in combination, lower levels of muscle activation or less external force was required to reduce the curvature of the spine, when compared with either muscle activation or external force applied

  2. The Potential Radiative Forcing of Global Land Use and Land Cover Change Activities

    NASA Astrophysics Data System (ADS)

    Ward, D. S.; Mahowald, N. M.; Kloster, S.

    2014-12-01

    Given the expected increase in pressure on land resources over the next century, there is a need to understand the total impacts of activities associated with land use and land cover change (LULCC). Here we quantify these impacts using the radiative forcing metric, including forcings from changes in long-lived greenhouse gases, tropospheric ozone, aerosol effects, and land surface albedo. We estimate radiative forcings from the different agents for historical LULCC and for six future projections using simulations from the National Center for Atmospheric Research Community Land Model and Community Atmosphere Models and additional offline analyses. When all forcing agents are considered together we show that 45% (+30%, -20%) of the present-day (2010) anthropogenic radiative forcing can be attributed to LULCC. Changes in the emission of non-CO2 greenhouse gases and aerosols from LULCC enhance the total LULCC radiative forcing by a factor of 2 to 3 with respect to the forcing from CO2 alone. In contrast, the non-CO2 forcings from fossil fuel burning are roughly neutral, due largely to the negative (cooling) impact of aerosols from these sources. We partition the global LULCC radiative forcing into three major sources: direct modification of land cover (e.g. deforestation), agricultural activities, and fire regime changes. Contributions from deforestation and agriculture are roughly equal in the present day, while changes to wildfire activity impose a small negative forcing globally. In 2100, deforestation activities comprise the majority of the LULCC radiative forcing for all projections except one (Representative Concentration Pathway (RCP) 4.5). This suggests that realistic scenarios of future forest area change are essential for projecting the contribution of LULCC to climate change. However, the commonly used RCP land cover change projections all include decreases in global deforestation rates over the next 85 years. To place an upper bound on the potential

  3. Thermal Noise Reduction of Mechanical Oscillators by Actively Controlled External Dissipative Forces

    NASA Technical Reports Server (NTRS)

    Liang, Shoudan; Medich, David; Czajkowsky, Daniel M.; Sheng, Sitong; Yuan, Jian-Yang; Shao, Zhifeng

    1999-01-01

    We show that the thermal fluctuations of very soft mechanical oscillators, such as the cantilever in an atomic force microscope (AFM), can be reduced without changing the stiffness of the spring or having to lower the environment temperature. We derive a theoretical relationship between the thermal fluctuations of an oscillator and an actively external-dissipative force. This relationship is verified by experiments with an AFM cantilever where the external active force is coupled through a magnetic field. With simple instrumentation, we have reduced the thermal noise amplitude of the cantilever by a factor of 3.4, achieving an apparent temperature of 25 K with the environment at 295K. This active noise reduction approach can significantly improve the accuracy of static position or static force measurements in a number of practical applications.

  4. Mechanical Allostery: Evidence for a Force Requirement in the Proteolytic Activation of Notch

    PubMed Central

    Gordon, Wendy R.; Zimmerman, Brandon; He, Li; Miles, Laura J.; Huang, Jiuhong; Tiyanont, Kittichoat; McArthur, Debbie G.; Aster, Jon C.; Perrimon, Norbert; Loparo, Joseph J.; Blacklow, Stephen C.

    2015-01-01

    Summary Ligands stimulate Notch receptors by inducing regulated intramembrane proteolysis (RIP) to produce a transcriptional effector. Notch activation requires unmasking of a metalloprotease cleavage site remote from the site of ligand binding, raising the question of how proteolytic sensitivity is achieved. Here, we show that application of physiologically relevant forces to the regulatory switch results in sensitivity to metalloprotease cleavage, and that bound ligands induce Notch signal transduction in cells only in the presence of applied mechanical force. Synthetic receptor-ligand systems that remove the native ligand-receptor interaction also activate Notch by inducing proteolysis of the regulatory switch. Together, these studies show that mechanical force exerted by signal-sending cells is required for ligand-induced Notch activation, and establish that force-induced proteolysis can act as a mechanism of cellular mechanotransduction. PMID:26051539

  5. Distribution of the forces produced by motor unit activity in the human flexor digitorum profundus

    PubMed Central

    Kilbreath, S L; Gorman, R B; Raymond, J; Gandevia, S C

    2002-01-01

    In humans, the flexor digitorum profundus (FDP), which is a multi-tendoned muscle, produces forces that flex the four distal interphalangeal joints of the fingers. We determined whether the force associated with activity in a single motor unit in the FDP was confined to a single finger or distributed to more than one finger during a natural grasp. The discharge of single low-threshold motor units (n = 69) was recorded at sites across the muscle during weak voluntary grasping involving all fingers and spike-triggered averaging of the forces under each of the finger pads was used to assess the distribution pattern. Spike-triggered averaging revealed that time-locked changes in force occurred under the ‘test’ finger (that finger on which the unit principally acted) as well as under the ‘non-test’ fingers. However, for the index-, middle- and ring-finger units, the changes in force under non-test fingers were typically small (< 20 % of those under the test finger). For little-finger units, the mean changes in force under the adjacent ring finger were large (>50 % of those under the test finger). The distribution of forces by little-finger units differed significantly from that for each of the other three fingers. Apart from increases in force under non-test fingers, there was occasional unloading of adjacent fingers (22/267 combinations), usually affecting the index finger. The increases in force under the test finger correlated significantly with the background force for units acting on the middle, ring and little fingers. During a functional grasp, the activity of single units in the FDP allows for a relatively selective control of forces at the tips of the index, middle and ring fingers, but this is limited for little-finger units. PMID:12181299

  6. Calcium-activated force of human muscle fibers following a standardized eccentric contraction.

    PubMed

    Choi, Seung Jun; Widrick, Jeffrey J

    2010-12-01

    Peak Ca(2+)-activated specific force (force/fiber cross-sectional area) of human chemically skinned vastus lateralis muscle fiber segments was determined before and after a fixed-end contraction or an eccentric contraction of standardized magnitude (+0.25 optimal fiber length) and velocity (0.50 unloaded shortening velocity). Fiber myosin heavy chain (MHC) isoform content was assayed by SDS-PAGE. Posteccentric force deficit, a marker of damage, was similar for type I and IIa fibers but threefold greater for type IIa/IIx hybrid fibers. A fixed-end contraction had no significant effect on force. Multiple linear regression revealed that posteccentric force was explained by a model consisting of a fiber type-independent and a fiber type-specific component (r(2) = 0.91). Preeccentric specific force was directly associated with a greater posteccentric force deficit. When preeccentric force was held constant, type I and IIa fibers showed identical susceptibility to damage, while type IIa/IIx fibers showed a significantly greater force loss. This heightened sensitivity to damage was directly related to the amount of type IIx MHC in the hybrid fiber. Our model reveals a fiber-type sensitivity of the myofilament lattice or cytoskeleton to mechanical strain that can be described as follows: type IIa/IIx > type IIa = type I. If these properties extend to fibers in vivo, then alterations in the number of type IIa/IIx fibers may modify a muscle's susceptibility to eccentric damage.

  7. 75 FR 22497 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-29

    ... Force on Veterans Small Business Development By the authority vested in me as President by the... ``Act''), and in order to establish an interagency task force to coordinate the efforts of Federal... Administration (Administrator) shall establish within the Small Business Administration an Interagency Task...

  8. Exploring Work and Development Options to Reduce Early Labour Force Exit of Mature Aged Australians

    ERIC Educational Resources Information Center

    Pillay, Hitendra; Kelly, Kathy; Tones, Megan

    2008-01-01

    Early labour force exit is a significant challenge associated with the ageing workforce in Australia and many other developed countries. A reduction and increased flexibility of work hours has been suggested to improve labour force participation of the mature aged cohort. However, little is known about mature aged workers' aspirations for…

  9. Development of a Knee-gap Force Measurement Device to Evaluate Quantitative Lower Limb Muscular Strength of the Elderly

    NASA Astrophysics Data System (ADS)

    Yamashita, Kazuhiko; Imaizumi, Kazuya; Iwakami, Yumi; Sato, Mitsuru; Nakajima, Sawako; Ino, Shuichi; Koyama, Hironori; Kawasumi, Masashi; Ifukube, Toru

    Falling is one of the most serious problems for the elderly. It is thought that lower limb muscular strength greatly affects falls of the elderly. The aim of this study is to develop a safe, easy-to-use and quantitative device of knee-gap force measurement for evaluation of the lower limb muscular strength, and additionally, we examined it for efficiency. We examined from the three viewpoints. In the results, 1. the knee-gap force is clearly associated with the strength of muscle contraction estimated by electromyogram in each muscle for the hip joint adductors. Therefore, the proposed device for the measurement of knee-gap force correctly estimates the activity of the hip joint adductors, which is closely related with the activities of daily living. 2.The results of knee-gap force measured from 170 people aging from middle age to elderly, including some persons who are suffering from physical frailness on a clinical estimation. In the group of healthy elderly knee-gap force was decreased by 16%, while that of the physically frail elderly was decreased by 34% in comparison to middle age.3. Furthermore, the correlation coefficient between the knee-gap force and 10m obstacle walking time was found to be -0.57 (negative correlation). It means that the ambulatory ability is decreased along with the knee-gap force being decreased. This indicates a possibility easily to estimate risk of falling by the knee-gap force, because the decrease of lower limb muscular strength and ambulatory ability is a factor of increased falling risk.

  10. A Development of Force Plate for Biomechanics Analysis of Standing and Walking

    NASA Astrophysics Data System (ADS)

    Wardoyo, S.; Hutajulu, P. T.; Togibasa, O.

    2016-08-01

    Force plates are known as an excellent teaching aid to demonstrate the kinematics and dynamics of motion and commonly used in biomechanics laboratories to measure ground forces involved in the motion of human. It is consist of a metal plate with sensors attached to give an electrical output proportional to the force on the plate. Moreover, force plates are useful for examining the kinetic characteristics of an athlete's movement. They provide information about the external forces involved in movement that can aid a coach or sports scientist to quantitatively evaluate the athlete's skill development. In this study, we develop our prototype of force plate with less than 100,- simply by using flexible force transducer attached inside rubber matt, in the form of square blocks (dimension: 250 mm × 150 mm × 10 mm), with maximum load up to 60 kg. The handmade force plate was tested by applying biomechanics analysis for standing and walking. The testing was done on Experimental Soccer Courses’ students at the Department of Physical Education, Health and Recreation, University of Cenderawasih. The design of the force plate system together with biomechanics analysis will be discussed.

  11. Coordinated integrin activation by actin-dependent force during T-cell migration.

    PubMed

    Nordenfelt, Pontus; Elliott, Hunter L; Springer, Timothy A

    2016-10-10

    For a cell to move forward it must convert chemical energy into mechanical propulsion. Force produced by actin polymerization can generate traction across the plasma membrane by transmission through integrins to their ligands. However, the role this force plays in integrin activation is unknown. Here we show that integrin activity and cytoskeletal dynamics are reciprocally linked, where actin-dependent force itself appears to regulate integrin activity. We generated fluorescent tension-sensing constructs of integrin αLβ2 (LFA-1) to visualize intramolecular tension during cell migration. Using quantitative imaging of migrating T cells, we correlate tension in the αL or β2 subunit with cell and actin dynamics. We find that actin engagement produces tension within the β2 subunit to induce and stabilize an active integrin conformational state and that this requires intact talin and kindlin motifs. This supports a general mechanism where localized actin polymerization can coordinate activation of the complex machinery required for cell migration.

  12. Satellite cascade attitude control via fuzzy PD controller with active force control under momentum dumping

    NASA Astrophysics Data System (ADS)

    Ismail, Z.; Varatharajoo, R.

    2016-10-01

    In this paper, fuzzy proportional-derivative (PD) controller with active force control (AFC) scheme is studied and employed in the satellite attitude control system equipped with reaction wheels. The momentum dumping is enabled via proportional integral (PI) controller as the system is impractical without momentum dumping control. The attitude controllers are developed together with their governing equations and evaluated through numerical treatment with respect to a reference satellite mission. From the results, it is evident that the three axis attitudes accuracies can be improved up to ±0.001 degree through the fuzzy PD controller with AFC scheme for the attitude control. In addition, the three-axis wheel angular momentums are well maintained during the attitude control tasks.

  13. Implementing Joint Operational Access: From Concept to Joint Force Development

    DTIC Science & Technology

    2014-01-01

    multiple DOTMLPF-P gover - nance processes across the Department of Defense (DOD). Finally, pulling all of the various activities together related to JOA...eral Martin E . Dempsey signed the Joint Concept for Entry Operations (JCEO) on April 7, 2014. 5 Sustaining U.S. Global Leadership, 5. 6 JOAC, 33–36

  14. Comparisons of peak ground reaction force and rate of force development during variations of the power clean.

    PubMed

    Comfort, Paul; Allen, Mark; Graham-Smith, Phillip

    2011-05-01

    The aim of this investigation was to determine the differences in vertical ground reaction forces and rate of force development (RFD) during variations of the power clean. Elite rugby league players (n = 11; age 21 ± 1.63 years; height 181.56 ± 2.61 cm; body mass 93.65 ± 6.84 kg) performed 1 set of 3 repetitions of the power clean, hang-power clean, midthigh power clean, or midthigh clean pull, using 60% of 1-repetition maximum power clean, in a randomized order, while standing on a force platform. Differences in peak vertical ground reaction forces (F(z)) and instantaneous RFD between lifts were analyzed via 1-way analysis of variance and Bonferroni post hoc analysis. Statistical analysis revealed a significantly (p < 0.001) greater peak F(z) during the midthigh power clean (2,801.7 ± 195.4 N) and the midthigh clean pull (2,880.2 ± 236.2 N) compared to both the power clean (2,306.24 ± 240.47 N) and the hang-power clean (2,442.9 ± 293.2 N). The midthigh power clean (14,655.8 ± 4,535.1 N·s⁻¹) and the midthigh clean pull (15,320.6 ± 3,533.3 N·s⁻¹) also demonstrated significantly (p < 0.001) greater instantaneous RFD when compared to both the power clean (8,839.7 ± 2,940.4 N·s⁻¹) and the hang-power clean (9,768.9 ± 4,012.4 N·s⁻¹). From the findings of this study, when training to maximize peak F(z) and RFD the midthigh power clean and midthigh clean pull appear to be the most advantageous variations of the power clean to perform.

  15. Analysis of ground reaction force and electromyographic activity of the gastrocnemius muscle during double support.

    PubMed

    Sousa, Andreia S P; Santos, Rubim; Oliveira, Francisco P M; Carvalho, Paulo; Tavares, João Manuel R S

    2012-05-01

    Mechanisms associated with energy expenditure during gait have been extensively researched and studied. According to the double-inverted pendulum model energy expenditure is higher during double support, as lower limbs need to work to redirect the centre of mass velocity. This study looks into how the ground reaction force of one limb affects the muscle activity required by the medial gastrocnemius of the contralateral limb during step-to-step transition. Thirty-five subjects were monitored as to the medial gastrocnemius electromyographic activity of one limb and the ground reaction force of the contralateral limb during double support. After determination of the Pearson correlation coefficient (r), a moderate correlation was observed between the medial gastrocnemius electromyographic activity of the dominant leg and the vertical (Fz) and anteroposterior (Fy) components of ground reaction force of the non-dominant leg (r = 0.797, p < 0.000 1; r = -0.807, p < 0.000 1). A weak and moderate correlation was observed between the medial gastrocnemius electromyographic activity of the non-dominant leg and the Fz and Fy of the dominant leg, respectively (r = 0.442, p = 0.018; r = -0.684 p < 0.000 1). The results obtained suggest that during double support, ground reaction force is associated with the electromyographic activity of the contralateral medial gastrocnemius and that there is an increased dependence between the ground reaction force of the non-dominant leg and the electromyographic activity of the dominant medial gastrocnemius.

  16. Validation and Verification of Operational Land Analysis Activities at the Air Force Weather Agency

    NASA Technical Reports Server (NTRS)

    Shaw, Michael; Kumar, Sujay V.; Peters-Lidard, Christa D.; Cetola, Jeffrey

    2012-01-01

    The NASA developed Land Information System (LIS) is the Air Force Weather Agency's (AFWA) operational Land Data Assimilation System (LDAS) combining real time precipitation observations and analyses, global forecast model data, vegetation, terrain, and soil parameters with the community Noah land surface model, along with other hydrology module options, to generate profile analyses of global soil moisture, soil temperature, and other important land surface characteristics. (1) A range of satellite data products and surface observations used to generate the land analysis products (2) Global, 1/4 deg spatial resolution (3) Model analysis generated at 3 hours. AFWA recognizes the importance of operational benchmarking and uncertainty characterization for land surface modeling and is developing standard methods, software, and metrics to verify and/or validate LIS output products. To facilitate this and other needs for land analysis activities at AFWA, the Model Evaluation Toolkit (MET) -- a joint product of the National Center for Atmospheric Research Developmental Testbed Center (NCAR DTC), AFWA, and the user community -- and the Land surface Verification Toolkit (LVT), developed at the Goddard Space Flight Center (GSFC), have been adapted to operational benchmarking needs of AFWA's land characterization activities.

  17. Bioelectric activity of skeletal muscle under conditions of alternating action of g-Forces and weightlessness

    NASA Technical Reports Server (NTRS)

    Yuganov, Y. M.; Kasyan, I. I.; Asyamolov, B. F.

    1975-01-01

    The bioelectric activity of the musculature of animals and man was studied during alternating g-forces and weightlessness. The appropriate conditions were reproduced in flight along a parabolic curve; in this case, weightlessness lasting 25-30 sec alternated with g-forces of about 2 g magnitude. Quite regular changes in the bioelectric activity of various groups of muscles were disclosed under g-forces and in weightlessness. Thus, muscle biopotential amplitudes of 130-180 microvolt in horizontal flight, increased to 190-330 microvolt under g-forces. In the subsequent weightlessness, an abrupt reduction in oscillation voltage was observed and, in a number of cases, phenomena, similar to the picture of bioelectric silence were noted.

  18. Force interacts with macromolecular structure in activation of TGF-β.

    PubMed

    Dong, Xianchi; Zhao, Bo; Iacob, Roxana E; Zhu, Jianghai; Koksal, Adem C; Lu, Chafen; Engen, John R; Springer, Timothy A

    2017-02-02

    Integrins are adhesion receptors that transmit force across the plasma membrane between extracellular ligands and the actin cytoskeleton. In activation of the transforming growth factor-β1 precursor (pro-TGF-β1), integrins bind to the prodomain, apply force, and release the TGF-β growth factor. However, we know little about how integrins bind macromolecular ligands in the extracellular matrix or transmit force to them. Here we show how integrin αVβ6 binds pro-TGF-β1 in an orientation biologically relevant for force-dependent release of TGF-β from latency. The conformation of the prodomain integrin-binding motif differs in the presence and absence of integrin binding; differences extend well outside the interface and illustrate how integrins can remodel extracellular matrix. Remodelled residues outside the interface stabilize the integrin-bound conformation, adopt a conformation similar to earlier-evolving family members, and show how macromolecular components outside the binding motif contribute to integrin recognition. Regions in and outside the highly interdigitated interface stabilize a specific integrin/pro-TGF-β orientation that defines the pathway through these macromolecules which actin-cytoskeleton-generated tensile force takes when applied through the integrin β-subunit. Simulations of force-dependent activation of TGF-β demonstrate evolutionary specializations for force application through the TGF-β prodomain and through the β- and not α-subunit of the integrin.

  19. Force-activated reactivity switch in a bimolecular chemical reaction at the single molecule level

    NASA Astrophysics Data System (ADS)

    Szoszkiewicz, Robert; Garcia-Manyes, Sergi; Liang, Jian; Kuo, Tzu-Ling; Fernandez, Julio M.

    2009-10-01

    Mechanical force is a distinct and usually less explored way to activate chemical reaction because it can deform the reacting molecules along a well-defined direction of the reaction coordinate. However, the effect of mechanical force on the free- energy surface that governs a chemical reaction is still largely unknown. The combination of protein engineering with single-molecule force-clamp spectroscopy allows us to study the influence of mechanical force on the rate at which a protein disulfide bond is reduced by some reducing agents in a bimolecular substitution reaction (so-called SN2). We found that cleavage of a protein disulfide bond by hydroxide anions exhibits an abrupt reactivity ``switch'' at 500 pN, after which the accelerating effect of force on the rate of an SN2 chemical reaction greatly diminishes. We propose that an abrupt force- induced conformational change of the protein disulfide bond shifts its ground state, drastically changing its reactivity in SN2 chemical reactions. Our experiments directly demonstrate the action of a force-activated switch in the chemical reactivity of a single molecule. References: S. Garcia-Manyes, J. Liang, R. Szoszkiewicz, T-L. Kuo and J. M. Fernandez, Nature Chemistry, 1, 236-242, 2009.

  20. Correlation of fingertip shear force direction with somatosensory cortical activity in monkey

    PubMed Central

    Fortier-Poisson, Pascal; Langlais, Jean-Sébastien

    2015-01-01

    To examine the activity of somatosensory cortex (S1) neurons to self-generated shear forces on the index and thumb, two monkeys were trained to grasp a stationary metal tab with a key grip and exert forces without the fingers slipping in one of four orthogonal directions for 1 s. A majority (∼85%) of slowly adapting and rapidly adapting (RA) S1 neurons had activity modulated with shear force direction. The cells were recorded mainly in areas 1 and 2 of the S1, although some area 3b neurons also responded to shear direction or magnitude. The preferred shear vectors were distributed in every direction, with tuning arcs varying from 50° to 170°. Some RA neurons sensitive to dynamic shear force direction also responded to static shear force but within a narrower range, suggesting that the direction of the shear force may influence the adaptation rate. Other neurons were modulated with shear forces in diametrically opposite directions. The directional sensitivity of S1 cortical neurons is consistent with recordings from cutaneous afferents showing that shear direction, even without slip, is a powerful stimulus to S1 neurons. PMID:26467520

  1. Radiological Air Sampling. Protocol Development for the Canadian Forces

    DTIC Science & Technology

    2003-03-01

    that filter must be removed from the sampler and counted by some method. If the efficiency of the radiation detector is D (in units of count rate per...unit activity), then the count rate R of the radiation detector will be R = CVFD. In practice, C is the unknown quantity. V is known from the sampling...Potential Solutions The problem, then, is that all air samples contain radon and thoron daughters that emit alpha, beta, and gamma radiation . Moreover

  2. Effects of non-gravitational forces on orbital evolution of active Centaurs

    NASA Astrophysics Data System (ADS)

    Churyumov, Klim; Kovalenko, Nataliya

    2016-07-01

    Currently there are 26 active Centaurs known among 121 discovered .In the present study we have investigated the influence of cometary activity on their orbital evolution by using orbital evolution integrators. Since there is no information on exact values of non-gravitational forces for these cometary Centaurs, because of their large heliocentric distances, we assumed their non-gravitational forces as the one for comet Halley with coefficient of 1/r^{2}, where r is perihelion distance. As a result we got the differences in perihelion passage dates for active Centaurs and differences in their perihelion distances during one period around the Sun and longer time-span.

  3. Active damping of modal vibrations by force apportioning. [for spacecraft structures

    NASA Technical Reports Server (NTRS)

    Hallauer, W. L., Jr.; Barthelemy, J.-F. M.

    1980-01-01

    The theory and numerical simulation of active structural damping is described which requires few discrete control thrusters positioned on the structure. A particular apportioning of coherently phased control forces is applied for each vibration mode which is to be damped; this strongly affects the damped vibration mode, while minimally exciting all other modes. The force apportioning used is that which would tune a target mode if the structure was being shaken in a model vibration test. In contrast to model testing, the forces are varied temporally so as to dampen, rather than excite, the target mode(s).

  4. Active force generation in cross-linked filament bundles without motor proteins.

    PubMed

    Walcott, Sam; Sun, Sean X

    2010-11-01

    Cytoskeletal filaments often interact laterally through cross-linking proteins, contributing to passive cellular viscoelasticity and, perhaps surprisingly, active force generation. We present a theory, based on the formation and rupture of cross-linker bonds, that relates molecular properties of those interactions to the macroscale mechanics of filament bundles. Computing the force-velocity relation for such a bundle, we demonstrate significant contractile forces in the absence of molecular motors. This theory provides insight into cytokinesis, cytoskeletal mechanics, and stress-fiber contraction.

  5. Development and validation of a method to directly measure the cable force during the hammer throw.

    PubMed

    Brice, Sara M; Ness, Kevin F; Rosemond, Doug; Lyons, Keith; Davis, Mark

    2008-05-01

    The development of cable force during hammer-throw turns is crucial to the throw distance. In this paper, we present a method that is capable of measuring cable force in real time and, as it does not interfere with technique, it is capable of providing immediate feedback to coaches and athletes during training. A strain gauge was mounted on the wires of three hammers to measure the tension in the wire and an elite male hammer thrower executed three throws with each hammer. The output from the gauges was recorded by a data logger positioned on the lower back of the thrower. The throws were captured by three high-speed video cameras and the three-dimensional position of the hammer's head was determined by digitizing the images manually. The five best throws were analysed. The force acting on the hammer's head was calculated from Newton's second law of motion and this was compared with the force measured via the strain gauge. Qualitatively the time dependence of the two forces was essentially the same, although the measured force showed more detail in the troughs of the force-time curves. Quantitatively the average difference between the measured and calculated forces over the five throws was 76 N, which corresponds to a difference of 3.8% for a cable force of 2000 N.

  6. Effects of fiber type on force depression after active shortening in skeletal muscle.

    PubMed

    Joumaa, V; Power, G A; Hisey, B; Caicedo, A; Stutz, J; Herzog, W

    2015-07-16

    The aim of this study was to investigate force depression in Type I and Type II muscle fibers. Experiments were performed using skinned fibers from rabbit soleus and psoas muscles. Force depression was quantified after active fiber shortening from an average sarcomere length (SL) of 3.2µ m to an average SL of 2.6 µm at an absolute speed of 0.115f iber length/s and at a relative speed corresponding to 17% of the unloaded shortening velocity (V0) in each type of fibers. Force decay and mechanical work during shortening were also compared between fiber types. After mechanical testing, each fiber was subjected to myosin heavy chain (MHC) analysis in order to confirm its type (Type I expressing MHC I, and Type II expressing MHC IId). Type II fibers showed greater steady-state force depression after active shortening at a speed of 0.115 fiber length/s than Type I fibers (14.5±1.5% versus 7.8±1.7%). Moreover, at this absolute shortening speed, Type I fibers showed a significantly greater rate of force decay during shortening and produced less mechanical work than Type II fibers. When active shortening was performed at the same relative speed (17% V0), the difference in force depression between fiber types was abolished. These results suggest that no intrinsic differences were at the origin of the disparate force depressions observed in Type I and Type II fibers when actively shortened at the same absolute speed, but rather their distinct force-velocity relationships.

  7. Cortical activity differs between position- and force-control knee extension tasks.

    PubMed

    Poortvliet, Peter C; Tucker, Kylie J; Finnigan, Simon; Scott, Dion; Sowman, Paul; Hodges, Paul W

    2015-12-01

    Neural control differs between position- and force-control tasks as evident from divergent effects of fatigue and pain. Unlike force-control tasks, position-control tasks focus on a postural goal to maintain a joint angle. Cortical involvement is suggested to be less during postural control, but whether this differs between position- and force-control paradigms remains unclear. Coherence estimates the functional communication between spatially distinct active regions within the cortex (cortico-cortical coherence; CCC) and between the cortex and muscles (corticomuscular coherence; CMC). We investigated whether cortical involvement differed between force-control and more posturally focused, position-control tasks. Seventeen adults performed position- and force-control knee extensor efforts at a submaximal load (10 % maximum voluntary contraction). Surface electromyography was recorded from the right knee extensor and flexor muscles and brain activity using electroencephalography (EEG). CCC and CMC in the beta (13-30 Hz) and gamma (30-45 Hz) frequency bands were calculated between combinations of intra- and inter-hemispheric pairs of electrodes, and between four EEG electrodes that approximated the left motor cortical area, and right knee extensor EMG, respectively. Differences in EEG power and muscle activity were also calculated. CCC was greater across distributed regions in the force-control task. Beta EEG power in the left hemisphere was higher for the position-control task. Although averaged CMC data differed between tasks, there was no task difference for individual CMC data. Muscle activity and force did not differ between tasks. The results demonstrate differential cortical contributions to control force- versus position-control tasks. This might contribute to differences in performance outcomes of these tasks that have been shown previously.

  8. The intrinsic conformational features of amino acids from a protein coil library and their applications in force field development.

    PubMed

    Jiang, Fan; Han, Wei; Wu, Yun-Dong

    2013-03-14

    The local conformational (φ, ψ, χ) preferences of amino acid residues remain an active research area, which are important for the development of protein force fields. In this perspective article, we first summarize spectroscopic studies of alanine-based short peptides in aqueous solution. While most studies indicate a preference for the P(II) conformation in the unfolded state over α and β conformations, significant variations are also observed. A statistical analysis from various coil libraries of high-resolution protein structures is then summarized, which gives a more coherent view of the local conformational features. The φ, ψ, χ distributions of the 20 amino acids have been obtained from a protein coil library, considering both backbone and side-chain conformational preferences. The intrinsic side-chain χ(1) rotamer preference and χ(1)-dependent Ramachandran plot can be generally understood by combining the interaction of the side-chain Cγ/Oγ atom with two neighboring backbone peptide groups. Current all-atom force fields such as AMBER ff99sb-ILDN, ff03 and OPLS-AA/L do not reproduce these distributions well. A method has been developed by combining the φ, ψ plot of alanine with the influence of side-chain χ(1) rotamers to derive the local conformational features of various amino acids. It has been further applied to improve the OPLS-AA force field. The modified force field (OPLS-AA/C) reproduces experimental (3)J coupling constants for various short peptides quite well. It also better reproduces the temperature-dependence of the helix-coil transition for alanine-based peptides. The new force field can fold a series of peptides and proteins with various secondary structures to their experimental structures. MD simulations of several globular proteins using the improved force field give significantly less deviation (RMSD) to experimental structures. The results indicate that the local conformational features from coil libraries are valuable for

  9. Regional Quality Assurance Activity in Higher Education in Southeast Asia: Its Characteristics and Driving Forces

    ERIC Educational Resources Information Center

    Umemiya, Naoki

    2008-01-01

    This article analyses the characteristics and driving forces of regional quality assurance activity in Southeast Asia, which has been actively promoted in recent years by the ASEAN University Network, an organisation for higher education under the auspices of the Association of Southeast Asian Nations (ASEAN). There are now more collaborative…

  10. Armed Forces and National Development in the Case of the Republic of Indonesia

    DTIC Science & Technology

    1990-03-01

    REPUBLIC OF INDONESIA by Sukirno March, 1990 Thesis Advisor: R. A. McGonigal Approved for public release; distribution is unlimited. 4.] Unclassified...8217, , N. .’ t ’ tt &c~so 11. TITLE (Include Security Classification) Armed Forces and National Development, in the case of the Republic of Indonesia . 12...GROUP SUBGROUP Republic of Indonesia , National Development, Armed Forces. 19 ABSTRACT (continue on reverse if necessary and identify by block number

  11. Mentoring and Leadership Development in the Officer Corps of the United States Air Force

    DTIC Science & Technology

    1984-09-01

    universal in its effects . Hypothesis 10 is important in its finding that mentored officers view mentoring as being a more valuable tool for leadership ...0 MENTORING AND LEADERSHIP DEVELOPMENT IN THE OFFICER CORPS FOF THE UNITED STATES AIR FORCE THESIS F D E Michael E. UeckerCaptain, USAF CZ’ AFIT/GSM...AND LEADERSHIP DEVELOPMENT IN THE OFFICER CORPS OF THE UNITED STATES AIR FORCE THESIS - Michael E. Uecker Captain, USAF AFIT/GSM/LSY/84S-30 DTICF-il

  12. Development of walking analysis system consisting of mobile force plate and motion sensor.

    PubMed

    Adachi, Wataru; Tsujiuchi, Nobutaka; Koizumi, Takayuki; Aikawa, Masataka; Shiojima, Kouzou; Tsuchiya, Youtaro; Inoue, Yoshio

    2011-01-01

    In walking analysis, which is one useful method for efficient physical rehabilitation, the ground reaction force, the center of pressure, and the body orientation data are measured during walking. In the past, these data were measured by a 3D motion analysis system consisting of high-speed cameras and force plates, which must be installed in the floor. However, a conventional 3D motion analysis system can measure the ground reaction force and the center of pressure just on force plates during a few steps. In addition, the subjects' stride lengths are limited because they have to walk on the center of the force plate. These problems can be resolved by converting conventional devices into wearable devices. We used a measuring device consisting of portable force plates and motion sensors. We developed a walking analysis system that calculates the ground reaction force, the center of pressure, and the body orientations and measured a walking subject to estimate this system. We simultaneously used a conventional 3D motion analysis system to compare with our development system and showed its validity for measurements of ground reaction force and the center of pressure.

  13. Automobile Engine Development, Task Force Assessment, Preliminary Report.

    ERIC Educational Resources Information Center

    Caretto, L. S.; And Others

    This report presents a comprehensive survey of current knowledge and ongoing research and development projects in the area of vehicular emissions and control. Information provided attempts to answer the questions: how can proposed standards be met with existing technology and what additional research would be required to obtain desired control…

  14. Developing Air Force Strategic Leadership - A Career Long Process

    DTIC Science & Technology

    2012-05-14

    remove the current impediments to early strategic leader development and pursue career long engagement with a focus on tools like social media to help...enable future strategic leaders the time to pursue these opportunities. One area for increased study is the use of social media . Social media have the

  15. 78 FR 49729 - Takes of Marine Mammals Incidental to Specified Activities; U.S. Air Force Launches, Aircraft and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-15

    ... Specified Activities; U.S. Air Force Launches, Aircraft and Helicopter Operations, and Harbor Activities Related to Launch Vehicles From Vandenberg Air Force Base (VAFB), California AGENCY: National Marine... has received a request from the U.S. Air Force (USAF) for authorization to take marine...

  16. Impact of tropomyosin isoform composition on fast skeletal muscle thin filament regulation and force development.

    PubMed

    Scellini, B; Piroddi, N; Flint, G V; Regnier, M; Poggesi, C; Tesi, C

    2015-02-01

    Tropomyosin (Tm) plays a central role in the regulation of muscle contraction and is present in three main isoforms in skeletal and cardiac muscles. In the present work we studied the functional role of α- and βTm on force development by modifying the isoform composition of rabbit psoas skeletal muscle myofibrils and of regulated thin filaments for in vitro motility measurements. Skeletal myofibril regulatory proteins were extracted (78%) and replaced (98%) with Tm isoforms as homogenous ααTm or ββTm dimers and the functional effects were measured. Maximal Ca(2+) activated force was the same in ααTm versus ββTm myofibrils, but ββTm myofibrils showed a marked slowing of relaxation and an impairment of regulation under resting conditions compared to ααTm and controls. ββTm myofibrils also showed a significantly shorter slack sarcomere length and a marked increase in resting tension. Both these mechanical features were almost completely abolished by 10 mM 2,3-butanedione 2-monoxime, suggesting the presence of a significant degree of Ca(2+)-independent cross-bridge formation in ββTm myofibrils. Finally, in motility assay experiments in the absence of Ca(2+) (pCa 9.0), complete regulation of thin filaments required greater ββTm versus ααTm concentrations, while at full activation (pCa 5.0) no effect was observed on maximal thin filament motility speed. We infer from these observations that high contents of ββTm in skeletal muscle result in partial Ca(2+)-independent activation of thin filaments at rest, and longer-lasting and less complete tension relaxation following Ca(2+) removal.

  17. Installation Development Environmental Assessment Travis Air Force Base, California

    DTIC Science & Technology

    2007-11-01

    area predominantly have a thermic soil temperature regime (the mean annual soil temperature is 15 degrees Celsius [°C] or higher but lower than 22°C...ranges from sea level to 660 feet (200 meters) in the foothills surrounding the Central Valley. The valley floor is almost flat, and relief is small...even along the borders of the area. The Final EA of Installation Development Travis AFB, CA November 2007 3-15 flatness of the valley floor

  18. Air Force Research Laboratory High Power Electric Propulsion Technology Development

    DTIC Science & Technology

    2009-10-27

    are currently less mature than the Hall thruster variants. Comparisons of candidate technologies are evaluated with VASIMR , a well publicized high...propellants. However, FRCs are currently less mature than the Hall thruster variants. Comparisons of candidate technologies are evaluated with VASIMR ...publicized VASIMR VX-200, a nominal 200-kW dual thruster system currently in development by Ad Astra for the International Space Station. This

  19. Air Force Officer Qualifying Test Form O: Development and Standardization.

    DTIC Science & Technology

    1986-08-01

    the subtests using the Kuder - Richardson Formula 20. The subtests were then combined to form the five composites, and the reliabilities of the composites...were based on a formula developed by Wherry and Gaylord (1943). Tables 5 and 6 present the reliabilities and standard errors of measurement of Form 0...statistics, reliabilities , and intercorrelatlons were computed and found to be similar to corresponding Form N statistics. Standardization of Form 0 was

  20. Ground reaction forces, kinematics, and muscle activations during the windmill softball pitch.

    PubMed

    Oliver, Gretchen D; Plummer, Hillary

    2011-07-01

    The aims of the present study were to examine quantitatively ground reaction forces, kinematics, and muscle activations during the windmill softball pitch, and to determine relationships between knee valgus and muscle activations, ball velocity and muscle activation as well as ball velocity and ground reaction forces. It was hypothesized that there would be an inverse relationship between degree of knee valgus and muscle activation, a direct relationship between ground reaction forces and ball velocity, and non-stride leg muscle activations and ball velocity. Ten female windmill softball pitchers (age 17.6 ± 3.47 years, stature 1.67 ± 0.07 m, weight 67.4 ± 12.2 kg) participated. Dependent variables were ball velocity, surface electromyographic (sEMG), kinematic, and kinetic data while the participant was the independent variable. Stride foot contact reported peak vertical forces of 179% body weight. There were positive relationships between ball velocity and ground reaction force (r = 0.758, n = 10, P = 0.029) as well as ball velocity and non-stride leg gluteus maximus (r = 0.851, n = 10, P = 0.007) and medius (r = 0.760, n = 10, P = 0.029) muscle activity, while there was no notable relationship between knee valgus and muscle activation. As the windmill softball pitcher increased ball velocity, her vertical ground reaction forces also increased. Proper conditioning of the lumbopelvic-hip complex, including the gluteals, is essential for injury prevention. From the data presented, it is evident that bilateral strength and conditioning of the gluteal muscle group is salient in the windmill softball pitch as an attempt to decrease incidence of injury.

  1. Differential roles of regulatory light chain and myosin binding protein-C phosphorylations in the modulation of cardiac force development

    SciTech Connect

    Colson, Brett A.; Locher, Matthew R.; Bekyarova, Tanya; Patel, Jitandrakumar R.; Fitzsimons, Daniel P.; Irving, Thomas C.; Moss, Richard L.

    2010-05-25

    Phosphorylation of myosin regulatory light chain (RLC) by myosin light chain kinase (MLCK) and myosin binding protein-C (cMyBP-C) by protein kinase A (PKA) independently accelerate the kinetics of force development in ventricular myocardium. However, while MLCK treatment has been shown to increase the Ca{sup 2+} sensitivity of force (pCa{sub 50}), PKA treatment has been shown to decrease pCa{sub 50}, presumably due to cardiac troponin I phosphorylation. Further, MLCK treatment increases Ca{sup 2+}-independent force and maximum Ca{sup 2+}-activated force, whereas PKA treatment has no effect on either force. To investigate the structural basis underlying the kinase-specific differential effects on steady-state force, we used synchrotron low-angle X-ray diffraction to compare equatorial intensity ratios (I{sub 1,1}/I{sub 1,0}) to assess the proximity of myosin cross-bridge mass relative to actin and to compare lattice spacings (d{sub 1,0}) to assess the inter-thick filament spacing in skinned myocardium following treatment with either MLCK or PKA. As we showed previously, PKA phosphorylation of cMyBP-C increases I{sub 1,1}/I{sub 1,0} and, as hypothesized, treatment with MLCK also increased I{sub 1,1}/I{sub 1,0}, which can explain the accelerated rates of force development during activation. Importantly, interfilament spacing was reduced by {approx}2 nm ({Delta} 3.5%) with MLCK treatment, but did not change with PKA treatment. Thus, RLC or cMyBP-C phosphorylation increases the proximity of cross-bridges to actin, but only RLC phosphorylation affects lattice spacing, which suggests that RLC and cMyBP-C modulate the kinetics of force development by similar structural mechanisms; however, the effect of RLC phosphorylation to increase the Ca{sup 2+} sensitivity of force is mediated by a distinct mechanism, most probably involving changes in interfilament spacing.

  2. Auditory and Acoustic Research & Development at Air Force Research Laboratory (AFRL)

    DTIC Science & Technology

    2010-09-01

    Communication Earpiece System (ACCES), high performance active noise reduction earplugs, helmets specifically designed to reduce bone conducted noise... Earpiece System), high performance active noise reduction earplugs, helmets specifically designed to reduce bone conducted noise, tactical hearing...distribution unlimited. ABBREVIATIONS AAM - Advanced Acoustic Model ACCES - Attenuating Custom Communication Earpiece System AFR - Air Force Regulation

  3. Force field development with GOMC, a fast new Monte Carlo molecular simulation code

    NASA Astrophysics Data System (ADS)

    Mick, Jason Richard

    In this work GOMC (GPU Optimized Monte Carlo) a new fast, flexible, and free molecular Monte Carlo code for the simulation atomistic chemical systems is presented. The results of a large Lennard-Jonesium simulation in the Gibbs ensemble is presented. Force fields developed using the code are also presented. To fit the models a quantitative fitting process is outlined using a scoring function and heat maps. The presented n-6 force fields include force fields for noble gases and branched alkanes. These force fields are shown to be the most accurate LJ or n-6 force fields to date for these compounds, capable of reproducing pure fluid behavior and binary mixture behavior to a high degree of accuracy.

  4. Development of 1-DOF manipulator with variable rheological joint for instantaneous force

    NASA Astrophysics Data System (ADS)

    Majima, T.; Nagai, S.; Tomori, H.; Nakamura, T.

    2013-02-01

    Highly rigid actuators such as a geared motor or hydraulic actuator are widely used in industrial robots. To obtain high-speed motion, actuators need to increase the actuator output. However, to increase high-rigidity actuators output, it is necessary to make actuators larger. In contrast, humans perform motions with instantaneous force such as jumping or throwing by using muscles. These instantaneous forces are realized by accumulating potential energy to the muscles and the muscles releasing the energy in a short time. Therefore, in this study a 1-DOF manipulator with variable rheological joint for instantaneous force using an artificial muscle and a magnetorheological (MR) brake was developed. In this paper, the method of generating instantaneous force for this manipulator was proposed. Further, the experiment of the proposed method was also conducted. As a result, generating instantaneous force by proposed method was realized.

  5. 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.

  6. How Force Might Activate Talin's Vinculin Binding Sites: SMD Reveals a Structural Mechanism

    PubMed Central

    Hytönen, Vesa P; Vogel, Viola

    2008-01-01

    Upon cell adhesion, talin physically couples the cytoskeleton via integrins to the extracellular matrix, and subsequent vinculin recruitment is enhanced by locally applied tensile force. Since the vinculin binding (VB) sites are buried in the talin rod under equilibrium conditions, the structural mechanism of how vinculin binding to talin is force-activated remains unknown. Taken together with experimental data, a biphasic vinculin binding model, as derived from steered molecular dynamics, provides high resolution structural insights how tensile mechanical force applied to the talin rod fragment (residues 486–889 constituting helices H1–H12) might activate the VB sites. Fragmentation of the rod into three helix subbundles is prerequisite to the sequential exposure of VB helices to water. Finally, unfolding of a VB helix into a completely stretched polypeptide might inhibit further binding of vinculin. The first events in fracturing the H1–H12 rods of talin1 and talin2 in subbundles are similar. The proposed force-activated α-helix swapping mechanism by which vinculin binding sites in talin rods are exposed works distinctly different from that of other force-activated bonds, including catch bonds. PMID:18282082

  7. Active Traction Force Response to Long-Term Cyclic Stretch Is Dependent on Cell Pre-stress.

    PubMed

    Cirka, Heather; Monterosso, Melissa; Diamantides, Nicole; Favreau, John; Wen, Qi; Billiar, Kristen

    2016-04-26

    Mechanical stimulation is recognized as a potent modulator of cellular behaviors such as proliferation, differentiation, and extracellular matrix assembly. However, the study of how cell-generated traction force changes in response to stretch is generally limited to short-term stimulation. The goal of this work is to determine how cells actively alter their traction force in response to long-term physiological cyclic stretch as a function of cell pre-stress. We have developed, to our knowledge, a novel method to assess traction force after long-term (24 h) uniaxial or biaxial cyclic stretch under conditions of high cell pre-stress with culture on stiff (7.5 kPa) polyacrylamide gels (with or without transforming growth factor β1 (TGF-β1)) and low pre-stress by treating with blebbistatin or culture on soft gels (0.6 kPa). In response to equibiaxial stretch, valvular interstitial cells on stiff substrates decreased their traction force (from 300 nN to 100 nN) and spread area (from 3000 to 2100 μm(2)). With uniaxial stretch, the cells had similar decreases in traction force and area and reoriented perpendicular to the stretch. TGF-β1-treated valvular interstitial cells had higher pre-stress (1100 nN) and exhibited a larger drop in traction force with uniaxial stretch, but the percentage changes in force and area with stretch were similar to the non-TGF-β1-treated group. Cells with inhibited myosin II motors increased traction force (from 41 nN to 63 nN) and slightly reoriented toward the stretch direction. In contrast, cells cultured on soft gels increased their traction force significantly, from 15 nN to 45 nN, doubled their spread area, elongated from an initially rounded morphology, and reoriented perpendicular to the uniaxial stretch. Contractile-moment measurements provided results consistent with total traction force measurements. The combined results indicate that the change in traction force in response to external cyclic stretch is dependent upon the

  8. [Development of food supply quality assurance system for armed forces].

    PubMed

    Plaksin, E I

    2012-01-01

    To study a serviceman's satisfaction with how nutrition was organized, the author elaborated a questionnaire containing the sections "nutrition organization quality assessment" and "mess food intake condition quality assessment". Different categories of military men taking food were inquired in a mess. The affirmation "I have no after-meal heartburn" became evidence that the sample was heterogeneous. For detailed analysis, the total sample was divided into two subgroups: those who had (Subgroup 1) and had not (Subgroup 2) a burning sensation after eating. Subgroup II servicemen gave lower scores on the questions about the comfort of food intake, the quality of dishes, a general attitude towards nutrition organization in the mess than did Subgroup I. The study has verified that the developed subsistence quality assurance system is of importance. The questionnaire has provided a valid assessment of the quality of the services given by the mess and revealed a reason for low scores.

  9. Fast skeletal muscle troponin activation increases force of mouse fast skeletal muscle and ameliorates weakness due to nebulin-deficiency.

    PubMed

    Lee, Eun-Jeong; De Winter, Josine M; Buck, Danielle; Jasper, Jeffrey R; Malik, Fady I; Labeit, Siegfried; Ottenheijm, Coen A; Granzier, Henk

    2013-01-01

    The effect of the fast skeletal muscle troponin activator, CK-2066260, on calcium-induced force development was studied in skinned fast skeletal muscle fibers from wildtype (WT) and nebulin deficient (NEB KO) mice. Nebulin is a sarcomeric protein that when absent (NEB KO mouse) or present at low levels (nemaline myopathy (NM) patients with NEB mutations) causes muscle weakness. We studied the effect of fast skeletal troponin activation on WT muscle and tested whether it might be a therapeutic mechanism to increase muscle strength in nebulin deficient muscle. We measured tension-pCa relations with and without added CK-2066260. Maximal active tension in NEB KO tibialis cranialis fibers in the absence of CK-2066260 was ∼60% less than in WT fibers, consistent with earlier work. CK-2066260 shifted the tension-calcium relationship leftwards, with the largest relative increase (up to 8-fold) at low to intermediate calcium levels. This was a general effect that was present in both WT and NEB KO fiber bundles. At pCa levels above ∼6.0 (i.e., calcium concentrations <1 µM), CK-2066260 increased tension of NEB KO fibers to beyond that of WT fibers. Crossbridge cycling kinetics were studied by measuring k(tr) (rate constant of force redevelopment following a rapid shortening/restretch). CK-2066260 greatly increased k(tr) at submaximal activation levels in both WT and NEB KO fiber bundles. We also studied the sarcomere length (SL) dependence of the CK-2066260 effect (SL 2.1 µm and 2.6 µm) and found that in the NEB KO fibers, CK-2066260 had a larger effect on calcium sensitivity at the long SL. We conclude that fast skeletal muscle troponin activation increases force at submaximal activation in both wildtype and NEB KO fiber bundles and, importantly, that this troponin activation is a potential therapeutic mechanism for increasing force in NM and other skeletal muscle diseases with loss of muscle strength.

  10. Force-activated reactivity switch in a bimolecular chemical reaction at the single molecule level

    NASA Astrophysics Data System (ADS)

    Szoszkiewicz, Robert; Garcia-Manyes, Sergi; Liang, Jian; Kuo, Tzu-Ling; Fernandez, Julio M.

    2010-03-01

    Mechanical force can deform the reacting molecules along a well-defined direction of the reaction coordinate. However, the effect of mechanical force on the free-energy surface that governs a chemical reaction is still largely unknown. The combination of protein engineering with single-molecule AFM force-clamp spectroscopy allows us to study the influence of mechanical force on the rate at which a protein disulfide bond is reduced by some reducing agents in a bimolecular substitution reaction (so-called SN2). We found that cleavage of a protein disulfide bond by hydroxide anions exhibits an abrupt reactivity ``switch'' at 500 pN, after which the accelerating effect of force on the rate of an SN2 chemical reaction greatly diminishes. We propose that an abrupt force-induced conformational change of the protein disulfide bond shifts its ground state, drastically changing its reactivity in SN2 chemical reactions. Our experiments directly demonstrate the action of a force-activated switch in the chemical reactivity of a single molecule. References: Sergi Garcia-Manyes, Jian Liang, Robert Szoszkiewicz, Tzu-Ling Kuo and Julio M. Fernandez, Nature Chemistry, 1, 236-242, 2009.

  11. Character Development at the United States Air Force Academy: A Phenomenological Case Study of Graduates' Reflections

    ERIC Educational Resources Information Center

    Smith, J. Micheal

    2010-01-01

    The United States Air Force Academy develops commissionable officers of character through an intense 4-year program that includes academic, athletic, and military education and training. The literature was silent on whether the Academy effectively develops character or, if so, how the development takes place. This was a phenomenological case study…

  12. Increasing physical activity. A report on recommendations of the Task Force on Community Preventive Services.

    PubMed

    2001-10-26

    The Task Force on Community Preventive Services (the Task Force) has conducted systematic reviews of community interventions to increase physical activity. The Task Force either strongly recommends or recommends six interventions: two informational approaches (i.e., communitywide campaigns and point-of-decision prompts to encourage use of stairs); three behavioral and social approaches (i.e., school-based physical education, social support interventions in community settings [e.g., setting up a buddy system or contracting with another person to complete specified levels of physical activity], and individually adapted health behavior change programs); and one intervention to increase physical activity by using environmental and policy approaches (i.e., creation of or enhanced access to places for physical activity, combined with informational outreach activities). The Task Force found insufficient evidence on which to base recommendations for classroom-based health education focused on information provision, behavioral skills, and social support interventions in family settings because of inconsistent findings; mass media campaigns, college-age physical education, and health education because of an insufficient number of studies; and classroom-based health education focusing on reducing television viewing and video game playing because of the lack of a demonstrated link between reduced time spent watching television or playing video games and increased physical activity. This report provides additional information regarding the recommendations, briefly describes how the reviews were conducted, and provides information that can help in applying the interventions locally.

  13. The optimization of force inputs for active structural acoustic control using a neural network

    NASA Technical Reports Server (NTRS)

    Cabell, R. H.; Lester, H. C.; Silcox, R. J.

    1992-01-01

    This paper investigates the use of a neural network to determine which force actuators, of a multi-actuator array, are best activated in order to achieve structural-acoustic control. The concept is demonstrated using a cylinder/cavity model on which the control forces, produced by piezoelectric actuators, are applied with the objective of reducing the interior noise. A two-layer neural network is employed and the back propagation solution is compared with the results calculated by a conventional, least-squares optimization analysis. The ability of the neural network to accurately and efficiently control actuator activation for interior noise reduction is demonstrated.

  14. Active control of low-frequency sound radiation by cylindrical shell with piezoelectric stack force actuators

    NASA Astrophysics Data System (ADS)

    Cao, Yin; Sun, Hongling; An, Fengyan; Li, Xiaodong

    2012-05-01

    A novel active control method of sound radiation from a cylindrical shell under axial excitations is proposed and theoretically analyzed. This control method is based on a pair of piezoelectric stack force actuators which are installed on the shell and parallel to the axial direction. The actuators are driven in phase and generate the same forces to control the vibration and the sound radiation of the cylindrical shell. The model considered is a fluid-loaded finite stiffened cylindrical shell with rigid end-caps and only low-frequency axial vibration modes are involved. Numerical simulations are performed to explore the required control forces and the optimal mounting positions of actuators under different cost functions. The results show that the proposed force actuators can reduce the radiated sound pressure of low-frequency axial modes in all directions.

  15. Stretch and shortening of skeletal muscles activated along the ascending limb of the force-length relation.

    PubMed

    Rassier, Dilson E; Pun, Clara

    2010-01-01

    There is a history dependence of skeletal muscle contraction. When muscles are activated and subsequently stretched, they produce a long lasting force enhancement. When muscles are activated and subsequently shortened, they produce a long-lasting force depression. The purposes of the studies shown in this chapter were (1) to evaluate if force enhancement and force depression are present along the ascending limb of the force-length (FL) relation, (2) to evaluate if the history-dependent properties of force production are associated with sarcomere length (SL) non-uniformity, and (3) to determine the effects of cross-bridge (de)activation on force depression. Isolated myofibrils were activated by either Ca²(+) or MgADP and were subjected to consecutive stretches or shortenings along the ascending limb of the FL relation, separated by periods (approximately 5 s) of isometric contraction. Force after stretch was higher than force after shortening when the contractions were produced at similar SLs. The difference in force could not be explained by SL non-uniformity. After shortening, MgADP activation produced forces that were higher than Ca²(+) activation. Since MgADP induces the formation of strongly bound cross-bridges, the result suggests that force depression following shortening is associated with cross-bridge deactivation.

  16. The influence of elbow joint angle on different phases of force development during maximal voluntary contraction.

    PubMed

    Jaskólski, A; Kisiel, K; Adach, Z; Jaskólska, A

    2000-12-01

    The first aim of the study was to find an elbow joint angle at which muscle can produce maximum voluntary force (Lo(MVC)) and to compare that angle with an angle at which the fastest rates of force development occur (Lo). The second aim of the study was to find if changes in MVC and force development speed at an angle smaller (Ls) and larger (Ll) than the optimal angle depend on whether Ls and Ll were compared to Lo or Ls and Ll to Lo(MVC). Twenty-four male physical education students were tested four times using the BIODYNA dynamometer to measure torque versus time at an optimal length, as well as at lengths that were shorter (Ls = optimal -30 degrees) and longer (Ll = optimal +50 degrees). The average values of optimal angles for force development indices (Lo) were similar to the angle at which maximum force was produced (Lo(MVC)); however, there was a small (5-10 degrees) difference between Lo and Lo(MVC) in the majority of subjects. The results showed that during elbow flexion with the forearm in the midrange position, the difference between Lo and Lo(MVC) was small and did not affect MVC; however, it had a significant effect on the relation between joint angle and force development speed.

  17. TRADEOFFs in climate effects through aircraft routing: forcing due to radiatively active gases

    NASA Astrophysics Data System (ADS)

    Stordal, F.; Gauss, M.; Myhre, G.; Mancini, E.; Hauglustaine, D. A.; Köhler, M. O.; Berntsen, T.; . G Stordal, E. J.; Iachetti, D.; Pitari, G.; Isaksen, I. S. A.

    2006-10-01

    We have estimated impacts of alternative aviation routings on the radiative forcing. Changes in ozone and OH have been estimated in four Chemistry Transport Models (CTMs) participating in the TRADEOFF project. Radiative forcings due to ozone and methane have been calculated accordingly. In addition radiative forcing due to CO2 is estimated based on fuel consumption. Three alternative routing cases are investigated; one scenario assuming additional polar routes and two scenarios assuming aircraft cruising at higher (+2000 ft) and lower (-6000 ft) altitudes. Results from the base case in year 2000 are included as a reference. Taking first a steady state backward looking approach, adding the changes in the forcing from ozone, CO2 and CH4, the ranges of the models used in this work are -0.8 to -1.8 and 0.3 to 0.6 m Wm-2 in the lower (-6000 ft) and higher (+2000 ft) cruise levels, respectively. In relative terms, flying 6000ft lower reduces the forcing by 5-10% compared to the current flight pattern, whereas flying higher, while saving fuel and presumably flying time, increases the forcing by about 2-3%. Taking next a forward looking approach we have estimated the integrated forcing (m Wm-2 yr) over 20 and 100 years time horizons. The relative contributions from each of the three climate gases are somewhat different from the backward looking approach. The differences are moderate adopting 100 year time horizon, whereas under the 20 year horizon CO2 naturally becomes less important relatively. Thus the forcing agents impact climate differently on various time scales. Also, we have found significant differences between the models for ozone and methane. We conclude that we are not yet at a point where we can include non-CO2 effects of aviation in emission trading schemes. Nevertheless, the rerouting cases that have been studied here yield relatively small changes in the radiative forcing due to the radiatively active gases.

  18. Effect of exercise training and myocardial infarction on force development and contractile kinetics in isolated canine myocardium.

    PubMed

    Canan, Benjamin D; Haizlip, Kaylan M; Xu, Ying; Monasky, Michelle M; Hiranandani, Nitisha; Milani-Nejad, Nima; Varian, Kenneth D; Slabaugh, Jessica L; Schultz, Eric J; Fedorov, Vadim V; Billman, George E; Janssen, Paul M L

    2016-04-15

    It is well known that moderate exercise training elicits a small increase in ventricular mass (i.e., a physiological hypertrophy) that has many beneficial effects on overall cardiac health. It is also well known that, when a myocardial infarction damages part of the heart, the remaining myocardium remodels to compensate for the loss of viable functioning myocardium. The effects of exercise training, myocardial infarction (MI), and their interaction on the contractile performance of the myocardium itself remain largely to be determined. The present study investigated the contractile properties and kinetics of right ventricular myocardium isolated from sedentary and exercise trained (10-12 wk progressively increasing treadmill running, begun 4 wk after MI induction) dogs with and without a left ventricular myocardial infarction. Exercise training increased force development, whereas MI decreased force development that was not improved by exercise training. Contractile kinetics were significantly slower in the trained dogs, whereas this impact of training was less or no longer present after MI. Length-dependent activation, both evaluated on contractile force and kinetics, was similar in all four groups. The control exercise-trained group exhibited a more positive force-frequency relationship compared with the sedentary control group while both sedentary and trained post-MI dogs had a more negative relationship. Last, the impact of the β-adrenergic receptor agonist isoproterenol resulted in a similar increase in force and acceleration of contractile kinetics in all groups. Thus, exercise training increased developed force but slowed contractile kinetics in control (noninfarcted animals), actions that were attenuated or completely absent in post-MI dogs.

  19. Active shortening protects against stretch-induced force deficits in human skeletal muscle.

    PubMed

    Saripalli, Anjali L; Sugg, Kristoffer B; Mendias, Christopher L; Brooks, Susan V; Claflin, Dennis R

    2017-02-23

    Skeletal muscle contraction results from molecular interactions of myosin "crossbridges" with adjacent actin filament binding sites. The binding of myosin to actin can be "weak" or "strong", and only strong binding states contribute to force production. During active shortening, the number of strongly-bound crossbridges declines with increasing shortening velocity. Forcibly stretching a muscle that is actively shortening at high velocity results in no apparent negative consequences whereas stretch of an isometrically (fixed-length) contracting muscle causes ultrastructural damage and a decline in force-generating capability. Our working hypothesis is that stretch-induced damage is uniquely attributable to the population of crossbridges that are strongly-bound. We tested the hypothesis that stretch-induced force deficits decline as the prevailing shortening velocity is increased. Experiments were performed on permeabilized segments of individual skeletal muscle fibers obtained from human subjects. Fibers were maximally activated and either allowed to generate maximum isometric force (Fo), or to shorten at velocities that resulted in force maintenance of ≈50% Fo or ≈2% Fo. For each test condition, a rapid stretch equivalent to 0.1 x optimal fiber length was applied. Relative to pre-stretch Fo, force deficits resulting from stretches applied during force maintenance of 100%, ≈50%, and ≈2% Fo were 23.2 ± 8.6%, 7.8 ± 4.2% and 0.3 ± 3.3%, respectively (mean ± SD, n=20). We conclude that stretch-induced damage declines with increasing shortening velocity, consistent with the working hypothesis that the fraction of strongly-bound crossbridges is a causative factor in the susceptibility of skeletal muscle to stretch-induced damage.

  20. Role of amygdala MAPK activation on immobility behavior of forced swim rats.

    PubMed

    Huang, Tung-Yi; Lin, Chih-Hung

    2006-10-02

    The role of amygdala mitogen-activated protein kinase (MAPK) in rats during a forced swim test was investigated. The variation of amygdala MAPK level was studied in control rats and early-life maternally deprived rats. A forced swim test was carried out to estimate the immobility level. The data showed that the immobility time of rats that received maternal deprivation in early life was longer than that of control rats and Western blot analysis also showed that the amygdala phospho-MAPK level in maternally deprived rats was almost two times higher than in control rats. Intra-amygdala infusion of PD098059 or U0126, MEK inhibitors, suppressed immobility behavior during the forced swim test in both rats. Western blot analysis also showed that the amygdala MAPK activities in both rats infused with MEK inhibitors were also suppressed in parallel with expression of immobility behavior. The suppressed MAPK activities as well as the restoration of immobility time returned to the original level 48 h later. These results suggest that amygdala MAPK activation might play a role in the regulation of immobility behavior in rats during the forced swim test. Moreover, it could provide a hint that amygdala MAPK activation might be involved in the formation of depression-like behavior.

  1. Force steadiness, muscle activity, and maximal muscle strength in subjects with subacromial impingement syndrome.

    PubMed

    Bandholm, Thomas; Rasmussen, Lars; Aagaard, Per; Jensen, Bente Rona; Diederichsen, Louise

    2006-11-01

    We investigated the effects of the subacromial impingement syndrome (SIS) on shoulder sensory-motor control and maximal shoulder muscle strength. It was hypothesized that both would be impaired due to chronic shoulder pain associated with the syndrome. Nine subjects with unilateral SIS who remained physically active in spite of shoulder pain and nine healthy matched controls were examined to determine isometric and isokinetic submaximal shoulder-abduction force steadiness at target forces corresponding to 20%, 27.5%, and 35% of the maximal shoulder abductor torque, and maximal shoulder muscle strength (MVC). Electromyographic (EMG) activity was assessed using surface and intramuscular recordings from eight shoulder muscles. Force steadiness was impaired in SIS subjects during concentric contractions at the highest target force level only, with muscle activity largely unaffected. No between-group differences in shoulder MVC were observed. The present data suggest that shoulder sensory-motor control is only mildly impaired in subjects with SIS who are able to continue with upper body physical activity in spite of shoulder pain. Thus, physical activity should be continued by patients with SIS, if possible, to avoid the loss in neural and muscle functions associated with inactivity.

  2. Developing an Assessment Framework for U.S. Air Force Building Partnerships Programs

    DTIC Science & Technology

    2010-01-01

    Planning Division , Directorate of Plans, Hq USAF. Library of Congress Cataloging-in-Publication Data Developing an assessment framework for U.S. Air...Era: The Strategic Importance of USAF Advisory and Assistance Missions, MG-509-AF, 2006. RAND Project AIR FORCE RAND Project AIR FORCE, a division ...Operations Training Division AF/A5X Air Staff Directorate of Regional Plans and Requirements AF/A5XS Air Staff Concepts, Strategy, and Wargaming Division

  3. Muscle force output and electromyographic activity in squats with various unstable surfaces.

    PubMed

    Saeterbakken, Atle H; Fimland, Marius S

    2013-01-01

    The purpose of the study was to compare force output and muscle activity of leg and trunk muscles in isometric squats executed on stable surface (i.e., floor), power board, BOSU ball, and balance cone. Fifteen healthy men (23.3 ± 2.7 years, mass: 80.5 ± 8.5 kg, height: 1.81 ± 0.09 m) volunteered. The force output and electromyographic (EMG) activities of the rectus femoris, vastus medialis, vastus lateralis, biceps femoris, soleus, rectus abdominis, oblique external, and erector spinae were assessed. The order of the surfaces was randomized. One familiarization session was executed before the experimental test. Compared with stable surface (749 ± 222 N), the force output using power board was similar (-7%, p = 0.320) but lower for BOSU ball (-19%, p = 0.003) and balance cone (-24%, p ≤ 0.001). The force output using BOSU ball and balance cone was approximately 13% (p = 0.037) and approximately 18% (p = 0.001) less than the power board. There were similar EMG activities between the surfaces in all muscles except for rectus femoris, in which stable squat provided greater EMG activity than did the other exercises (p = 0.004-0.030). Lower EMG activity was observed in the rectus femoris using balance cone compared with the BOSU ball (p = 0.030). In conclusion, increasing the instability of the surface during maximum effort isometric squats usually maintains the muscle activity of lower-limb and superficial trunk muscles although the force output is reduced. This suggests that unstable surfaces in the squat may be beneficial in rehabilitation and as a part of periodized training programs, because similar muscle activity can be achieved with reduced loads.

  4. 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,…

  5. A study of the formation of magnetically active solid dispersions of phenacetin using atomic and magnetic force microscopy.

    PubMed

    Usmanova, Liana Stanislavovna; Ziganshin, Marat Akhmedovich; Gorbatchuk, Valery Vilenovich; Ziganshina, Sufia Askhatovna; Bizyaev, Dmitry Anatolevich; Bukharaev, Anastas Akhmetovich; Mukhametzyanov, Timur Anvarovich; Gerasimov, Alexander Vladimirovich

    2017-01-01

    A lot of pharmaceutical substances have a poor solubility that limits their absorption and distribution to the targeted sites to elicit the desired action without causing untoward effects on healthy cells or tissues. For such drugs, new modes of delivery have to be developed for efficient and effective delivery of the drug to the target site. Formation of magnetically active solid dispersion of such drugs could be a useful approach to addressing this problem because they combine targeted delivery and good solubility. In this work, the distribution of superparamagnetic nanoparticles in the solid dispersion of polyethylene glycol with average molecular weight 950-1050 g/mol and phenacetin was studied using atomic force and magnetic force microscopy. The distribution of nanoparticles was found to be uniform in studied composites. Magnetically active solid dispersions may find application in the production of the capsulated drug delivery systems with enhanced solubility parameters.

  6. A study of the formation of magnetically active solid dispersions of phenacetin using atomic and magnetic force microscopy

    PubMed Central

    Usmanova, Liana Stanislavovna; Ziganshin, Marat Akhmedovich; Gorbatchuk, Valery Vilenovich; Ziganshina, Sufia Askhatovna; Bizyaev, Dmitry Anatolevich; Bukharaev, Anastas Akhmetovich; Mukhametzyanov, Timur Anvarovich; Gerasimov, Alexander Vladimirovich

    2017-01-01

    A lot of pharmaceutical substances have a poor solubility that limits their absorption and distribution to the targeted sites to elicit the desired action without causing untoward effects on healthy cells or tissues. For such drugs, new modes of delivery have to be developed for efficient and effective delivery of the drug to the target site. Formation of magnetically active solid dispersion of such drugs could be a useful approach to addressing this problem because they combine targeted delivery and good solubility. In this work, the distribution of superparamagnetic nanoparticles in the solid dispersion of polyethylene glycol with average molecular weight 950–1050 g/mol and phenacetin was studied using atomic force and magnetic force microscopy. The distribution of nanoparticles was found to be uniform in studied composites. Magnetically active solid dispersions may find application in the production of the capsulated drug delivery systems with enhanced solubility parameters. PMID:28217547

  7. Current radar responsive tag development activities at Sandia National Laboratories.

    SciTech Connect

    Plummer, Kenneth W.; Ormesher, Richard C.

    2003-09-01

    Over the past ten years, Sandia has developed RF radar responsive tag systems and supporting technologies for various government agencies and industry partners. RF tags can function as RF transmitters or radar transponders that enable tagging, tracking, and location determination functions. Expertise in tag architecture, microwave and radar design, signal analysis and processing techniques, digital design, modeling and simulation, and testing have been directly applicable to these tag programs. In general, the radar responsive tag designs have emphasized low power, small package size, and the ability to be detected by the radar at long ranges. Recently, there has been an interest in using radar responsive tags for Blue Force tracking and Combat ID (CID). The main reason for this interest is to allow airborne surveillance radars to easily distinguish U.S. assets from those of opposing forces. A Blue Force tracking capability would add materially to situational awareness. Combat ID is also an issue, as evidenced by the fact that approximately one-quarter of all U.S. casualties in the Gulf War took the form of ground troops killed by friendly fire. Because the evolution of warfare in the intervening decade has made asymmetric warfare the norm rather than the exception, swarming engagements in which U.S. forces will be freely intermixed with opposing forces is a situation that must be anticipated. Increasing utilization of precision munitions can be expected to drive fires progressively closer to engaged allied troops at times when visual de-confliction is not an option. In view of these trends, it becomes increasingly important that U.S. ground forces have a widely proliferated all-weather radar responsive tag that communicates to all-weather surveillance. The purpose of this paper is to provide an overview of the recent, current, and future radar responsive research and development activities at Sandia National Laboratories that support both the Blue Force Tracking

  8. Up-sliding Slantwise Vorticity Development and the complete vorticity equation with mass forcing

    NASA Astrophysics Data System (ADS)

    Cui, Xiaopeng; Gao, Shouting; Wu, Guoxiong

    2003-09-01

    The moist potential vorticity (MPV) equation is derived from complete atmospheric equations including the effect of mass forcing, with which the theory of Up-sliding Slantwise Vorticity Development (USVD) is proposed based on the theory of Slantwise Vorticity Development (SVD). When an air parcel slides up along a slantwise isentropic surface, its vertical component of relative vorticity will develop, and the steeper the isentropic surface is, the more violent the development will be. From the definition of MPV and the MPV equation produced here in, a complete vorticity equation is then put forward with mass forcing, which explicitly includes the effects of both internal forcings, such as variations of stability, baroclinicity, and vertical shear of horizontal wind, and external forcings, such as diabatic heating, friction, and mass forcing. When isentropic surfaces are flat, the complete vorticity equation matches its traditional counterpart. The physical interpretations of some of the items which are included in the complete vorticity equation but not in the traditional one are studied with a simplified model of the Changjiang-Huaihe Meiyu front. A 60-h simulation is then performed to reproduce a torrential rain event in the Changjiang-Huaihe region and the output of the model is studied qualitatively based on the theory of USVD. The result shows that the conditions of the theory of USVD are easily satisfied immediately in front of mesoscale rainstorms in the downwind direction, that is, the theory of USVD is important to the development and movement of these kinds of systems.

  9. Role of biomechanics and muscle activation strategy in the production of endpoint force patterns in the cat hindlimb.

    PubMed

    Lemay, Michel A; Bhowmik-Stoker, Manoshi; McConnell, George C; Grill, Warren M

    2007-01-01

    We used a musculoskeletal model of the cat hindlimb to compare the patterns of endpoint forces generated by all possible combination of 12 hindlimb muscles under three different muscle activation rules: homogeneous activation of muscles based on uniform activation levels, homogeneous activation of muscles based on uniform (normalized) force production, and activation based on the topography of spinal motoneuron pools. Force patterns were compared with the patterns obtained experimentally by microstimulation of the lumbar spinal cord in spinal intact cats. Magnitude and orientation of the force patterns were compared, as well as the proportion of the types found, and the proportions of patterns exhibiting points of zero force (equilibrium points). The force patterns obtained with the homogenous activation and motoneuron topography models were quite similar to those measured experimentally, with the differences being larger for the patterns from the normalized endpoint forces model. Differences in the proportions of types of force patterns between the three models and the experimental results were significant for each model. Both homogeneous activation and normalized endpoint force models produced similar proportions of equilibrium points as found experimentally. The results suggest that muscle biomechanics play an important role in limiting the number of endpoint force pattern types, and that muscle combinations activated at similar levels reproduced best the experimental results obtained with intraspinal microstimulation.

  10. Elasticity-induced force reversal between active spinning particles in dense passive media

    NASA Astrophysics Data System (ADS)

    Aragones, J. L.; Steimel, J. P.; Alexander-Katz, A.

    2016-04-01

    The self-organization of active particles is governed by their dynamic effective interactions. Such interactions are controlled by the medium in which such active agents reside. Here we study the interactions between active agents in a dense non-active medium. Our system consists of actuated, spinning, active particles embedded in a dense monolayer of passive, or non-active, particles. We demonstrate that the presence of the passive monolayer alters markedly the properties of the system and results in a reversal of the forces between active spinning particles from repulsive to attractive. The origin of such reversal is due to the coupling between the active stresses and elasticity of the system. This discovery provides a mechanism for the interaction between active agents in complex and structured media, opening up opportunities to tune the interaction range and directionality via the mechanical properties of the medium.

  11. Elasticity-induced force reversal between active spinning particles in dense passive media

    PubMed Central

    Aragones, J. L.; Steimel, J. P.; Alexander-Katz, A.

    2016-01-01

    The self-organization of active particles is governed by their dynamic effective interactions. Such interactions are controlled by the medium in which such active agents reside. Here we study the interactions between active agents in a dense non-active medium. Our system consists of actuated, spinning, active particles embedded in a dense monolayer of passive, or non-active, particles. We demonstrate that the presence of the passive monolayer alters markedly the properties of the system and results in a reversal of the forces between active spinning particles from repulsive to attractive. The origin of such reversal is due to the coupling between the active stresses and elasticity of the system. This discovery provides a mechanism for the interaction between active agents in complex and structured media, opening up opportunities to tune the interaction range and directionality via the mechanical properties of the medium. PMID:27112961

  12. Development of low temperature atomic force microscopy with an optical beam deflection system capable of simultaneously detecting the lateral and vertical forces

    NASA Astrophysics Data System (ADS)

    Arima, Eiji; Wen, Huanfei; Naitoh, Yoshitaka; Li, Yan Jun; Sugawara, Yasuhiro

    2016-09-01

    The atomic force microscopy (AFM) is a very important tool for imaging and investigating the complex force interactions on sample surfaces with high spatial resolution. In the AFM, two types of detection systems of the tip-sample interaction forces have been used: an optical detection system and an electrical detection system. In optical detection systems, such as optical beam deflection system or optical fiber interferometer system, both the lateral and the vertical tip-sample forces can be measured simultaneously. In electrical detection systems, such as qPlus or Kolibri sensors, either the lateral or vertical forces can be measured. Simultaneous measurement of the lateral and vertical interaction forces effectively allows investigation of force interactions because the force is a vector with magnitude and direction. In this study, we developed a low-temperature, frequency-modulation AFM using an optical beam deflection system to simultaneously measure the vertical and lateral forces. In this system, the heat sources, such as a laser diode and a current-to-voltage converter, for measuring the photocurrent of the four-segmented photodiode are located outside the observation chamber to avoid a temperature increase of the AFM unit. The focused optical beam is three-dimensionally adjustable on the back side of the cantilever. We demonstrate low-noise displacement measurement of the cantilever and successful atomic resolution imaging using the vertical and lateral forces at low temperatures.

  13. Development of low temperature atomic force microscopy with an optical beam deflection system capable of simultaneously detecting the lateral and vertical forces.

    PubMed

    Arima, Eiji; Wen, Huanfei; Naitoh, Yoshitaka; Li, Yan Jun; Sugawara, Yasuhiro

    2016-09-01

    The atomic force microscopy (AFM) is a very important tool for imaging and investigating the complex force interactions on sample surfaces with high spatial resolution. In the AFM, two types of detection systems of the tip-sample interaction forces have been used: an optical detection system and an electrical detection system. In optical detection systems, such as optical beam deflection system or optical fiber interferometer system, both the lateral and the vertical tip-sample forces can be measured simultaneously. In electrical detection systems, such as qPlus or Kolibri sensors, either the lateral or vertical forces can be measured. Simultaneous measurement of the lateral and vertical interaction forces effectively allows investigation of force interactions because the force is a vector with magnitude and direction. In this study, we developed a low-temperature, frequency-modulation AFM using an optical beam deflection system to simultaneously measure the vertical and lateral forces. In this system, the heat sources, such as a laser diode and a current-to-voltage converter, for measuring the photocurrent of the four-segmented photodiode are located outside the observation chamber to avoid a temperature increase of the AFM unit. The focused optical beam is three-dimensionally adjustable on the back side of the cantilever. We demonstrate low-noise displacement measurement of the cantilever and successful atomic resolution imaging using the vertical and lateral forces at low temperatures.

  14. Variability in Measurement of Swimming Forces: A Meta-Analysis of Passive and Active Drag

    ERIC Educational Resources Information Center

    Havriluk, Rod

    2007-01-01

    An analysis was conducted to identify sources of true and error variance in measuring swimming drag force to draw valid conclusions about performance factor effects. Passive drag studies were grouped according to methodological differences: tow line in pool, tow line in flume, and carriage in tow tank. Active drag studies were grouped according to…

  15. Pyrazinoic acid decreases the proton motive force, respiratory ATP synthesis activity, and cellular ATP levels.

    PubMed

    Lu, Ping; Haagsma, Anna C; Pham, Hoang; Maaskant, Janneke J; Mol, Selena; Lill, Holger; Bald, Dirk

    2011-11-01

    Pyrazinoic acid, the active form of the first-line antituberculosis drug pyrazinamide, decreased the proton motive force and respiratory ATP synthesis rates in subcellular mycobacterial membrane assays. Pyrazinoic acid also significantly lowered cellular ATP levels in Mycobacterium bovis BCG. These results indicate that the predominant mechanism of killing by this drug may operate by depletion of cellular ATP reserves.

  16. Reliability of EMG activity versus bite-force from human masticatory muscles

    PubMed Central

    Gonzalez, Y.; Iwasaki, L.R.; McCall, W.D.; Ohrbach, R.; Lozier, E.; Nickel, J.C.

    2011-01-01

    The reproducibility of electromyographic (EMG) activity in relation to static bite-force from masticatory muscles for a given biting situation is largely unknown. Our aim was to evaluate the reliability of EMG activity in relation to static bite-force in humans. Eighty-four subjects produced 5 unilateral static bites of different forces at different biting positions on molars and incisors, at two separate sessions, while surface EMG activities were recorded from temporalis, masseter, and suprahyoid muscles bilaterally. Intraclass Correlation Coefficients (ICCs) were used, where an ICC of ≥ 0.60 indicated good reliability of these slopes. ICCs for jaw closing muscles during molar biting were: temporalis ipsilateral 0.58 to 0.93 and contralateral 0.88 to 0.91, masseter ipsilateral 0.75 to 0.86 and contralateral 0.69 to 0.88; while during incisor biting were: temporalis ipsilateral 0.56 to 0.81 and contralateral 0.34 to 0.86, masseter ipsilateral 0.65 to 0.78 and contralateral 0.59 to 0.80. For the suprahyoid muscles the confidence intervals were mostly wide and most included zero. Slopes of the EMG activity versus bite-force for a given biting situation were reliable for temporalis and masseter muscles. These results support the use of these outcome measurements for the estimation and validation of mechanical models of the masticatory system. PMID:21564316

  17. A Monetary Repayment Model for Recoupment of the Educational Costs of Air Force Sponsored Graduate Education in Lieu of Completion of an Active Duty Service Commitment.

    ERIC Educational Resources Information Center

    Mangold, Sanford Dangler

    The study develops a model which enables the Air Force to initiate recoupment action against any officer, who is separating from active service prior to the completion of a graduate education Active Duty Service Commitment (ADSC). It is set up to determine the amount of money owed by the early existing officer, at any point in the ADSC. The…

  18. Effect of Female Education and Labor Force Ratio on Economic Development

    ERIC Educational Resources Information Center

    Turanli, Munevver; Taspinar Cengiz, Dicle; Turanli, Rona; Akdal, Serem

    2015-01-01

    This study investigates the effects of women's education and labor force ratio on the level of development in countries. We use a complete dataset covering 44 countries over the period 1990-2010. It comprises the following: education index, the ratio of girls to boys in primary and secondary education, income per capita, human development index,…

  19. 76 FR 56863 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-14

    ... Business Development. The Task Force is established pursuant to Executive Order 13540 and focused on coordinating the efforts of Federal agencies to improve capital, business development opportunities and pre... President, no later than one year after its first meeting, a report on the performance of its functions...

  20. Prediction of ground reaction forces and moments during various activities of daily living.

    PubMed

    Fluit, R; Andersen, M S; Kolk, S; Verdonschot, N; Koopman, H F J M

    2014-07-18

    Inverse dynamics based simulations on musculoskeletal models is a commonly used method for the analysis of human movement. Due to inaccuracies in the kinematic and force plate data, and a mismatch between the model and the subject, the equations of motion are violated when solving the inverse dynamics problem. As a result, dynamic inconsistency will exist and lead to residual forces and moments. In this study, we present and evaluate a computational method to perform inverse dynamics-based simulations without force plates, which both improves the dynamic consistency as well as removes the model׳s dependency on measured external forces. Using the equations of motion and a scaled musculoskeletal model, the ground reaction forces and moments (GRF&Ms) are derived from three-dimensional full-body motion. The method entails a dynamic contact model and optimization techniques to solve the indeterminacy problem during a double contact phase and, in contrast to previously proposed techniques, does not require training or empirical data. The method was applied to nine healthy subjects performing several Activities of Daily Living (ADLs) and evaluated with simultaneously measured force plate data. Except for the transverse ground reaction moment, no significant differences (P>0.05) were found between the mean predicted and measured GRF&Ms for almost all ADLs. The mean residual forces and moments, however, were significantly reduced (P>0.05) in almost all ADLs using our method compared to conventional inverse dynamic simulations. Hence, the proposed method may be used instead of raw force plate data in human movement analysis using inverse dynamics.

  1. Using the traditional model to evaluate the active force of the human lateral rectus muscle

    NASA Astrophysics Data System (ADS)

    Gao, ZhiPeng; Chen, WeiYi; Jing, Lin; Feng, PengFei; Wu, XiaoGang; Guo, HongMei

    2014-05-01

    The information on the force of extraocular muscles (EOMs) is beneficial for strabismus diagnosis and surgical planning, and a direct and simple method is important for surgeons to obtain these forces. Based on the traditional model, a numerical simulation method was proposed to achieve this aim, and then the active force of the lateral rectus (LR) muscle was successfully simulated when the eye rotated every angle from 0° to 30° in the horizontal plane from the nasal to the temporal side. In order to verify these simulations, the results were compared with the previous experimental data. The comparison shows that the simulation results diverged much more than the experimental data in the range of 0°-10°. The errors were corrected to make the simulation results closer to the experimental data. Finally, a general empirical equation was proposed to evaluate the active force of the LR muscle by fitting these data, which represent the relationship between the simulation forces and the contractive amounts of the LR muscle.

  2. Quantifying surface albedo and other direct biogeophysical climate forcings of forestry activities.

    PubMed

    Bright, Ryan M; Zhao, Kaiguang; Jackson, Robert B; Cherubini, Francesco

    2015-09-01

    By altering fluxes of heat, momentum, and moisture exchanges between the land surface and atmosphere, forestry and other land-use activities affect climate. Although long recognized scientifically as being important, these so-called biogeophysical forcings are rarely included in climate policies for forestry and other land management projects due to the many challenges associated with their quantification. Here, we review the scientific literature in the fields of atmospheric science and terrestrial ecology in light of three main objectives: (i) to elucidate the challenges associated with quantifying biogeophysical climate forcings connected to land use and land management, with a focus on the forestry sector; (ii) to identify and describe scientific approaches and/or metrics facilitating the quantification and interpretation of direct biogeophysical climate forcings; and (iii) to identify and recommend research priorities that can help overcome the challenges of their attribution to specific land-use activities, bridging the knowledge gap between the climate modeling, forest ecology, and resource management communities. We find that ignoring surface biogeophysics may mislead climate mitigation policies, yet existing metrics are unlikely to be sufficient. Successful metrics ought to (i) include both radiative and nonradiative climate forcings; (ii) reconcile disparities between biogeophysical and biogeochemical forcings, and (iii) acknowledge trade-offs between global and local climate benefits. We call for more coordinated research among terrestrial ecologists, resource managers, and coupled climate modelers to harmonize datasets, refine analytical techniques, and corroborate and validate metrics that are more amenable to analyses at the scale of an individual site or region.

  3. Sympathetic activation by the cold pressor test does not increase the muscle force generation capacity.

    PubMed

    Roatta, Silvestro; Farina, Dario

    2011-06-01

    A positive inotropic action by the sympathetic nervous system on skeletal muscles has been observed and investigated in animal and in vitro studies. This action provided a theoretical basis for the putative ergogenic action of catecholamines and adrenergic agonists, although there is no clear evidence of this effect in humans. The aim of this study was to investigate the occurrence of inotropic effects associated to physiological sympathetic activation in healthy subjects. The muscle force capacity was investigated in the tibialis anterior (n = 9 subjects) and in the soleus (n = 9) muscles electrically stimulated with single pulses and double pulses with variable interspike interval (4-1,000 ms) and short pulse trains (frequency: 5-14 Hz) before, during, and after sympathetic activation by the cold pressor test (CPT). CPT significantly decreased by 10.4 ± 7.2 and 10.6 ± 4.4% the force produced by single and double pulse stimulation, respectively, and produced smaller decreases in the force obtained by train stimulation in the tibialis anterior, while no significant changes were observed in either type of contraction in the soleus muscle. CPT failed to induce any increase in the force capacity of the investigated muscles. The prevalent decrease in force evidenced in this study supports the concept that the weakening sympathetic action on type I fiber, already shown to occur in humans, prevails over the putative potentiating action.

  4. The effect of muscle length on force depression after active shortening in soleus muscle of mice.

    PubMed

    Van Noten, Pieter; Van Leemputte, Marc

    2011-07-01

    Isometric muscle force after active shortening is reduced [force depression (FD)]. The mechanism is incompletely understood but work delivered during shortening has been suggested to be the main determinant of FD. However, whether muscle length affects the sensitivity of FD to work is unknown, although this information might add to the understanding of the phenomenon. The aim of this study is to investigate the length dependence of the FD/work ratio (Q). Therefore, isometric force production (ISO) of 10 incubated mouse soleus muscles was compared to isometric force after 0.6, 1.2, and 2.4 mm shortening (IAS) at different end lengths ranging from L(0) - 3 to L(0) + 1.8 mm in steps of 0.6 mm. FD was calculated as the force difference between an ISO and IAS contraction at the same activation time (6 s) and end length. We confirm the strong relation between FD and work at L(0) (R² = 0.92) and found that FD is length dependent with a maximum of 8.8 ± 0.3% at L(0) + 1.2 mm for 0.6 mm shortening amplitude. Q was only constant for short muscle lengths (<85% L(0)) but increased exponentially with increasing muscle length. The observed length dependence of Q indicates that FD is not only determined by work produced during shortening but also by a length-dependent factor, possibly actin compliance, which should be incorporated in any mechanism explaining FD.

  5. Active open boundary forcing using dual relaxation time-scales in downscaled ocean models

    NASA Astrophysics Data System (ADS)

    Herzfeld, M.; Gillibrand, P. A.

    2015-05-01

    Regional models actively forced with data from larger scale models at their open boundaries often contain motion at different time-scales (e.g. tidal and low frequency). These motions are not always individually well specified in the forcing data, and one may require a more active boundary forcing while the other exert less influence on the model interior. If a single relaxation time-scale is used to relax toward these data in the boundary equation, then this may be difficult. The method of fractional steps is used to introduce dual relaxation time-scales in an open boundary local flux adjustment scheme. This allows tidal and low frequency oscillations to be relaxed independently, resulting in a better overall solution than if a single relaxation parameter is optimized for tidal (short relaxation) or low frequency (long relaxation) boundary forcing. The dual method is compared to the single relaxation method for an idealized test case where a tidal signal is superimposed on a steady state low frequency solution, and a real application where the low frequency boundary forcing component is derived from a global circulation model for a region extending over the whole Great Barrier Reef, and a tidal signal subsequently superimposed.

  6. Optimization of Active Muscle Force-Length Models Using Least Squares Curve Fitting.

    PubMed

    Mohammed, Goran Abdulrahman; Hou, Ming

    2016-03-01

    The objective of this paper is to propose an asymmetric Gaussian function as an alternative to the existing active force-length models, and to optimize this model along with several other existing models by using the least squares curve fitting method. The minimal set of coefficients is identified for each of these models to facilitate the least squares curve fitting. Sarcomere simulated data and one set of rabbits extensor digitorum II experimental data are used to illustrate optimal curve fitting of the selected force-length functions. The results shows that all the curves fit reasonably well with the simulated and experimental data, while the Gordon-Huxley-Julian model and asymmetric Gaussian function are better than other functions in terms of statistical test scores root mean squared error and R-squared. However, the differences in RMSE scores are insignificant (0.3-6%) for simulated data and (0.2-5%) for experimental data. The proposed asymmetric Gaussian model and the method of parametrization of this and the other force-length models mentioned above can be used in the studies on active force-length relationships of skeletal muscles that generate forces to cause movements of human and animal bodies.

  7. Decoupling Principle Analysis and Development of a Parallel Three-Dimensional Force Sensor

    PubMed Central

    Zhao, Yanzhi; Jiao, Leihao; Weng, Dacheng; Zhang, Dan; Zheng, Rencheng

    2016-01-01

    In the development of the multi-dimensional force sensor, dimension coupling is the ubiquitous factor restricting the improvement of the measurement accuracy. To effectively reduce the influence of dimension coupling on the parallel multi-dimensional force sensor, a novel parallel three-dimensional force sensor is proposed using a mechanical decoupling principle, and the influence of the friction on dimension coupling is effectively reduced by making the friction rolling instead of sliding friction. In this paper, the mathematical model is established by combining with the structure model of the parallel three-dimensional force sensor, and the modeling and analysis of mechanical decoupling are carried out. The coupling degree (ε) of the designed sensor is defined and calculated, and the calculation results show that the mechanical decoupling parallel structure of the sensor possesses good decoupling performance. A prototype of the parallel three-dimensional force sensor was developed, and FEM analysis was carried out. The load calibration and data acquisition experiment system are built, and then calibration experiments were done. According to the calibration experiments, the measurement accuracy is less than 2.86% and the coupling accuracy is less than 3.02%. The experimental results show that the sensor system possesses high measuring accuracy, which provides a basis for the applied research of the parallel multi-dimensional force sensor. PMID:27649194

  8. Decoupling Principle Analysis and Development of a Parallel Three-Dimensional Force Sensor.

    PubMed

    Zhao, Yanzhi; Jiao, Leihao; Weng, Dacheng; Zhang, Dan; Zheng, Rencheng

    2016-09-15

    In the development of the multi-dimensional force sensor, dimension coupling is the ubiquitous factor restricting the improvement of the measurement accuracy. To effectively reduce the influence of dimension coupling on the parallel multi-dimensional force sensor, a novel parallel three-dimensional force sensor is proposed using a mechanical decoupling principle, and the influence of the friction on dimension coupling is effectively reduced by making the friction rolling instead of sliding friction. In this paper, the mathematical model is established by combining with the structure model of the parallel three-dimensional force sensor, and the modeling and analysis of mechanical decoupling are carried out. The coupling degree (ε) of the designed sensor is defined and calculated, and the calculation results show that the mechanical decoupling parallel structure of the sensor possesses good decoupling performance. A prototype of the parallel three-dimensional force sensor was developed, and FEM analysis was carried out. The load calibration and data acquisition experiment system are built, and then calibration experiments were done. According to the calibration experiments, the measurement accuracy is less than 2.86% and the coupling accuracy is less than 3.02%. The experimental results show that the sensor system possesses high measuring accuracy, which provides a basis for the applied research of the parallel multi-dimensional force sensor.

  9. Force adaptation transfers to untrained workspace regions in children: evidence for developing inverse dynamic motor models.

    PubMed

    Jansen-Osmann, Petra; Richter, Stefanie; Konczak, Jürgen; Kalveram, Karl-Theodor

    2002-03-01

    When humans perform goal-directed arm movements under the influence of an external damping force, they learn to adapt to these external dynamics. After removal of the external force field, they reveal kinematic aftereffects that are indicative of a neural controller that still compensates the no longer existing force. Such behavior suggests that the adult human nervous system uses a neural representation of inverse arm dynamics to control upper-extremity motion. Central to the notion of an inverse dynamic model (IDM) is that learning generalizes. Consequently, aftereffects should be observable even in untrained workspace regions. Adults have shown such behavior, but the ontogenetic development of this process remains unclear. This study examines the adaptive behavior of children and investigates whether learning a force field in one hemifield of the right arm workspace has an effect on force adaptation in the other hemifield. Thirty children (aged 6-10 years) and ten adults performed 30 degrees elbow flexion movements under two conditions of external damping (negative and null). We found that learning to compensate an external damping force transferred to the opposite hemifield, which indicates that a model of the limb dynamics rather than an association of visited space and experienced force was acquired. Aftereffects were more pronounced in the younger children and readaptation to a null-force condition was prolonged. This finding is consistent with the view that IDMs in children are imprecise neural representations of the actual arm dynamics. It indicates that the acquisition of IDMs is a developmental achievement and that the human motor system is inherently flexible enough to adapt to any novel force within the limits of the organism's biomechanics.

  10. A Methodology for Modeling the Flow of Military Personnel Across Air Force Active and Reserve Components

    DTIC Science & Technology

    2016-01-01

    C O R P O R A T I O N Research Report A Methodology for Modeling the Flow of Military Personnel Across Air Force Active and Reserve Components...Lisa M. Harrington, James H . Bigelow, Alexander Rothenberg, James Pita, Paul D. Emslie Limited Print and Electronic Distribution Rights This document...of a particular component—whether active , guard, or reserve. As a result, when personnel policies are implemented in one component, little is known

  11. Calcium uptake and force development by skinned muscle fibres in EGTA buffered solutions

    PubMed Central

    Ford, L. E.; Podolsky, R. J.

    1972-01-01

    1. The uptake of 45Ca and the development of force by segments of skinned muscle fibres were measured in Ca solutions buffered with EGTA. When the Ca ion concentration in these solutions was above the contraction threshold, Ca was accumulated by the sarcoplasmic reticulum during the delay phase before force developed. The uptake rate increased, and the length of the delay decreased, when the concentration of the calcium buffer was increased. 2. The maximum accumulation of Ca was 2-3 mM. Force developed, ending the delay phase, when the calcium uptake approached this maximum level. 3. The pattern of force development suggested that this process was often accompanied by a sudden release of accumulated Ca. 4. The relation between the kinetics of 45Ca uptake and the interaction of calcium with EGTA and the sarcoplasmic reticulum is discussed. The data indicate that at the low concentrations necessary for relaxation the sarcoplasmic reticulum takes up Ca fast enough to account for the rate at which force falls when intact muscle fibres relax. PMID:5046147

  12. Development of Si neural probe with piezoresistive force sensor for minimally invasive and precise monitoring of insertion forces

    NASA Astrophysics Data System (ADS)

    Harashima, Takuya; Morikawa, Takumi; Kino, Hisashi; Fukushima, Takafumi; Tanaka, Tetsu

    2017-04-01

    A Si neural probe is one of the most important tools for neurophysiology and brain science because of its various functions such as optical stimulation and drug delivery. However, the Si neural probe is not robust compared with a metal tetrode, and could be broken by mechanical stress caused by insertion to the brain. Therefore, the Si neural probe becomes more useful if it has a stress sensor that can measure mechanical forces applied to the probe so as not to be broken. In this paper, we proposed and fabricated the Si neural probe with a piezoresistive force sensor for minimally invasive and precise monitoring of insertion forces. The fabricated piezoresistive force sensor accurately measured forces and successfully detected insertion events without buckling or bending in the shank of the Si neural probe. This Si neural probe with a piezoresistive force sensor has become one of the most versatile tools for neurophysiology and brain science.

  13. Filament compliance influences cooperative activation of thin filaments and the dynamics of force production in skeletal muscle.

    PubMed

    Tanner, Bertrand C W; Daniel, Thomas L; Regnier, Michael

    2012-01-01

    Striated muscle contraction is a highly cooperative process initiated by Ca²⁺ binding to the troponin complex, which leads to tropomyosin movement and myosin cross-bridge (XB) formation along thin filaments. Experimental and computational studies suggest skeletal muscle fiber activation is greatly augmented by cooperative interactions between neighboring thin filament regulatory units (RU-RU cooperativity; 1 RU = 7 actin monomers+1 troponin complex+1 tropomyosin molecule). XB binding can also amplify thin filament activation through interactions with RUs (XB-RU cooperativity). Because these interactions occur with a temporal order, they can be considered kinetic forms of cooperativity. Our previous spatially-explicit models illustrated that mechanical forms of cooperativity also exist, arising from XB-induced XB binding (XB-XB cooperativity). These mechanical and kinetic forms of cooperativity are likely coordinated during muscle contraction, but the relative contribution from each of these mechanisms is difficult to separate experimentally. To investigate these contributions we built a multi-filament model of the half sarcomere, allowing RU activation kinetics to vary with the state of neighboring RUs or XBs. Simulations suggest Ca²⁺ binding to troponin activates a thin filament distance spanning 9 to 11 actins and coupled RU-RU interactions dominate the cooperative force response in skeletal muscle, consistent with measurements from rabbit psoas fibers. XB binding was critical for stabilizing thin filament activation, particularly at submaximal Ca²⁺ levels, even though XB-RU cooperativity amplified force less than RU-RU cooperativity. Similar to previous studies, XB-XB cooperativity scaled inversely with lattice stiffness, leading to slower rates of force development as stiffness decreased. Including RU-RU and XB-RU cooperativity in this model resulted in the novel prediction that the force-[Ca²⁺] relationship can vary due to filament and XB

  14. Endurance time, muscular activity and the hand/arm tremor for different exertion forces of holding.

    PubMed

    Lee, Tzu-Hsien

    2016-01-01

    This study aimed to examine the effects of exertion force on endurance time, muscular activity and hand/arm tremor during holding. Fifteen healthy young males were recruited as participants. The independent variable was exertion force (20%, 40%, 60% and 80% maximum holding capacity). The dependent variables were endurance time, muscular activity and hand/arm tremor. The results showed that endurance time decreased with exertion force while muscular activity and hand/arm tremor increased with exertion force. Hand/arm tremor increased with holding time. Endurance time of 40%, 60% and 80% maximum holding capacity was approximately 22.7%, 12.0% and 5.6% of that of 20% maximum holding capacity, respectively. The rms (root mean square) acceleration of hand/arm tremor of the final phase of holding was 2.27-, 1.33-, 1.20- and 1.73-fold of that of the initial phase of holding for 20%, 40%, 60% and 80% maximum holding capacity, respectively.

  15. Mechanical forces as information: an integrated approach to plant and animal development

    PubMed Central

    Hernández-Hernández, Valeria; Rueda, Denisse; Caballero, Lorena; Alvarez-Buylla, Elena R.; Benítez, Mariana

    2014-01-01

    Mechanical forces such as tension and compression act throughout growth and development of multicellular organisms. These forces not only affect the size and shape of the cells and tissues but are capable of modifying the expression of genes and the localization of molecular components within the cell, in the plasma membrane, and in the plant cell wall. The magnitude and direction of these physical forces change with cellular and tissue properties such as elasticity. Thus, mechanical forces and the mesoscopic fields that emerge from their local action constitute important sources of positional information. Moreover, physical and biochemical processes interact in non-linear ways during tissue and organ growth in plants and animals. In this review we discuss how such mechanical forces are generated, transmitted, and sensed in these two lineages of multicellular organisms to yield long-range positional information. In order to do so we first outline a potentially common basis for studying patterning and mechanosensing that relies on the structural principle of tensegrity, and discuss how tensegral structures might arise in plants and animals. We then provide some examples of morphogenesis in which mechanical forces appear to act as positional information during development, offering a possible explanation for ubiquitous processes, such as the formation of periodic structures. Such examples, we argue, can be interpreted in terms of tensegral phenomena. Finally, we discuss the hypothesis of mechanically isotropic points as a potentially generic mechanism for the localization and maintenance of stem-cell niches in multicellular organisms. This comparative approach aims to help uncovering generic mechanisms of morphogenesis and thus reach a better understanding of the evolution and development of multicellular phenotypes, focusing on the role of physical forces in these processes. PMID:24959170

  16. Resistance Training for Explosive and Maximal Strength: Effects on Early and Late Rate of Force Development

    PubMed Central

    Oliveira, Felipe B.D.; Oliveira, Anderson S.C.; Rizatto, Guilherme F.; Denadai, Benedito S.

    2013-01-01

    The aim of the present study was to verify whether strength training designed to improve explosive and maximal strength would influence rate of force development (RFD). Nine men participated in a 6-week knee extensors resistance training program and 9 matched subjects participated as controls. Throughout the training sessions, subjects were instructed to perform isometric knee extension as fast and forcefully as possible, achieving at least 90% maximal voluntary contraction as quickly as possible, hold it for 5 s, and relax. Fifteen seconds separated each repetition (6-10), and 2 min separated each set (3). Pre- and post-training measurements were maximal isometric knee extensor (MVC), RFD, and RFD relative to MVC (i.e., %MVC·s-1) in different time-epochs varying from 10 to 250 ms from the contraction onset. The MVC (Nm) increased by 19% (275.8 ± 64.9 vs. 329.8 ± 60.4, p < 0.001) after training. In addition, RFD (Nm·s-1) increased by 22-28% at time epochs up to 20 ms from the contraction onset (0-10 ms = 1679. 1 ± 597.1 vs. 2159.2 ± 475.2, p < 0.001; 0-20 ms = 1958.79 ± 640.3 vs. 2398.4 ± 479.6, p < 0. 01), with no changes verified in later time epochs. However, no training effects on RFD were found for the training group when RFD was normalized to MVC. No changes were found in the control group. In conclusion, very early and late RFD responded differently to a short period of resistance training for explosive and maximal strength. This time-specific RFD adaptation highlight that resistance training programs should consider the specific neuromuscular demands of each sport. Key Points The time-specific RFD adaptation evoked by resistance training highlight that the method of analyzing RFD is essential for the interpretation of results. Confirming previous data, maximal contractile RFD and maximal force can be differently influenced by resistance training. Thus, the resistance training programs should consider the specific neuromuscular demands of each sport

  17. Active and Progressive Exoskeleton Rehabilitation Using Multisource Information Fusion From EMG and Force-Position EPP.

    PubMed

    Fan, Yuanjie; Yin, Yuehong

    2013-12-01

    Although exoskeletons have received enormous attention and have been widely used in gait training and walking assistance in recent years, few reports addressed their application during early poststroke rehabilitation. This paper presents a healthcare technology for active and progressive early rehabilitation using multisource information fusion from surface electromyography and force-position extended physiological proprioception. The active-compliance control based on interaction force between patient and exoskeleton is applied to accelerate the recovery of the neuromuscular function, whereby progressive treatment through timely evaluation contributes to an effective and appropriate physical rehabilitation. Moreover, a clinic-oriented rehabilitation system, wherein a lower extremity exoskeleton with active compliance is mounted on a standing bed, is designed to ensure comfortable and secure rehabilitation according to the structure and control requirements. Preliminary experiments and clinical trial demonstrate valuable information on the feasibility, safety, and effectiveness of the progressive exoskeleton-assisted training.

  18. Development of a quartz tuning-fork-based force sensor for measurements in the tens of nanoNewton force range during nanomanipulation experiments

    SciTech Connect

    Oiko, V. T. A. Rodrigues, V.; Ugarte, D.; Martins, B. V. C.; Silva, P. C.

    2014-03-15

    Understanding the mechanical properties of nanoscale systems requires new experimental and theoretical tools. In particular, force sensors compatible with nanomechanical testing experiments and with sensitivity in the nN range are required. Here, we report the development and testing of a tuning-fork-based force sensor for in situ nanomanipulation experiments inside a scanning electron microscope. The sensor uses a very simple design for the electronics and it allows the direct and quantitative force measurement in the 1–100 nN force range. The sensor response is initially calibrated against a nN range force standard, as, for example, a calibrated Atomic Force Microscopy cantilever; subsequently, applied force values can be directly derived using only the electric signals generated by the tuning fork. Using a homemade nanomanipulator, the quantitative force sensor has been used to analyze the mechanical deformation of multi-walled carbon nanotube bundles, where we analyzed forces in the 5–40 nN range, measured with an error bar of a few nN.

  19. Induced Voltage Linear Extraction Method Using an Active Kelvin Bridge for Disturbing Force Self-Sensing.

    PubMed

    Yang, Yuanyuan; Wang, Lei; Tan, Jiubin; Zhao, Bo

    2016-05-20

    This paper presents an induced voltage linear extraction method for disturbing force self-sensing in the application of giant magnetostrictive actuators (GMAs). In this method, a Kelvin bridge combined with an active device is constructed instead of a conventional Wheatstone bridge for extraction of the induced voltage, and an additional GMA is adopted as a reference actuator in the self-sensing circuit in order to balance the circuit bridge. The linear fitting of the measurement data is done according to the linear relationship between the disturbing forces and the integral of the induced voltage. The experimental results confirm the good performance of the proposed method, and the self-sensitivity of the disturbing forces is better than 2.0 (mV·s)/N.

  20. Natural history and the formation of the human being: Kant on active forces.

    PubMed

    Waldow, Anik

    2016-08-01

    In his 1785-review of the Ideen zur Philosophie der Geschichte der Menschheit, Kant objects to Herder's conception of nature as being imbued with active forces. This attack is usually evaluated against the background of Kant's critical project and his epistemological concern to caution against the "metaphysical excess" of attributing immanent properties to matter. In this paper I explore a slightly different reading by investigating Kant's pre-critical account of creation and generation. The aim of this is to show that Kant's struggle with the forces of matter has a long history and revolves around one central problem: that of how to distinguish between the non-purposive forces of nature and the intentional powers of the mind. Given this history, the epistemic stricture that Kant's critical project imposes on him no longer appears to be the primary reason for his attack on Herder. It merely aggravates a problem that Kant has been battling with since his earliest writings.

  1. Coordinated integrin activation by actin-dependent force during T-cell migration

    PubMed Central

    Nordenfelt, Pontus; Elliott, Hunter L.; Springer, Timothy A.

    2016-01-01

    For a cell to move forward it must convert chemical energy into mechanical propulsion. Force produced by actin polymerization can generate traction across the plasma membrane by transmission through integrins to their ligands. However, the role this force plays in integrin activation is unknown. Here we show that integrin activity and cytoskeletal dynamics are reciprocally linked, where actin-dependent force itself appears to regulate integrin activity. We generated fluorescent tension-sensing constructs of integrin αLβ2 (LFA-1) to visualize intramolecular tension during cell migration. Using quantitative imaging of migrating T cells, we correlate tension in the αL or β2 subunit with cell and actin dynamics. We find that actin engagement produces tension within the β2 subunit to induce and stabilize an active integrin conformational state and that this requires intact talin and kindlin motifs. This supports a general mechanism where localized actin polymerization can coordinate activation of the complex machinery required for cell migration. PMID:27721490

  2. Atomistic insight into orthoborate-based ionic liquids: force field development and evaluation.

    PubMed

    Wang, Yong-Lei; Shah, Faiz Ullah; Glavatskih, Sergei; Antzutkin, Oleg N; Laaksonen, Aatto

    2014-07-24

    We have developed an all-atomistic force field for a new class of halogen-free chelated orthoborate-phosphonium ionic liquids. The force field is based on an AMBER framework with determination of force field parameters for phosphorus and boron atoms, as well as refinement of several available parameters. The bond and angle force constants were adjusted to fit vibration frequency data derived from both experimental measurements and ab initio calculations. The force field parameters for several dihedral angles were obtained by fitting torsion energy profiles deduced from ab initio calculations. To validate the proposed force field parameters, atomistic simulations were performed for 12 ionic liquids consisting of tetraalkylphosphonium cations and chelated orthoborate anions. The predicted densities for neat ionic liquids and the [P6,6,6,14][BOB] sample, with a water content of approximately 2.3-2.5 wt %, are in excellent agreement with available experimental data. The potential energy components of 12 ionic liquids were discussed in detail. The radial distribution functions and spatial distribution functions were analyzed and visualized to probe the microscopic ionic structures of these ionic liquids. There are mainly four high-probability regions of chelated orthoborate anions distributed around tetraalkylphosphonium cations in the first solvation shell, and such probability distribution functions are strongly influenced by the size of anions.

  3. 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…

  4. Trunk Muscle Activation and Estimating Spinal Compressive Force in Rope and Harness Vertical Dance.

    PubMed

    Wilson, Margaret; Dai, Boyi; Zhu, Qin; Humphrey, Neil

    2015-12-01

    Rope and harness vertical dance takes place off the floor with the dancer suspended from his or her center of mass in a harness attached to a rope from a point overhead. Vertical dance represents a novel environment for training and performing in which expected stresses on the dancer's body are different from those that take place during dance on the floor. Two male and eleven female dancers with training in vertical dance performed six typical vertical dance movements with electromyography (EMG) electrodes placed bilaterally on rectus abdominus, external oblique, erector spinae, and latissimus dorsi. EMG data were expressed as a percentage of maximum voluntary isometric contraction (MVIC). A simplified musculoskeletal model based on muscle activation for these four muscle groups was used to estimate the compressive force on the spine. The greatest muscle activation for erector spinae and latissimus dorsi and the greatest trunk compressive forces were seen in vertical axis positions where the dancer was moving the trunk into a hyper-extended position. The greatest muscle activation for rectus abdominus and external oblique and the second highest compressive force were seen in a supine position with the arms and legs extended away from the center of mass (COM). The least muscle activation occurred in positions where the limbs were hanging below the torso. These movements also showed relatively low muscle activation compression forces. Post-test survey results revealed that dancers felt comfortable in these positions; however, observation of some positions indicated insufficient muscular control. Computing the relative contribution of muscles, expressed as muscle activation and estimated spinal compression, provided a measure of how much the muscle groups were working to support the spine and the rest of the dancer's body in the different movements tested. Additionally, identifying typical muscle recruitment patterns in each movement will help identify key exercises

  5. Forty Years of Research and Development at Griffiss Air Force Base, June 1951-June 1991

    DTIC Science & Technology

    1991-06-01

    Broadband Tee Sections Sperry Gyroscope Co. developed and constructed tees for all standard waveguide sizes for the frequency range 2600 to 40,000...Co. for rework, since it did not conform to Air Force specifications. Broadband Transmission Line Adapters RADC accepted delivery of two waveguide-to...type "N" adapters from Microwave Development Laboratory. The broadband transmission line adapter series developed under this program would cover the

  6. A meteorological forcing data set for global crop modeling: Development, evaluation, and intercomparison

    NASA Astrophysics Data System (ADS)

    Iizumi, Toshichika; Okada, Masashi; Yokozawza, Masayuki

    2014-01-01

    The Global Risk Assessment toward Stable Production of Food (GRASP) project uses global crop models to evaluate the impacts on global food security by changes in climate extremes, water resources, and land use. Such models require meteorological forcing data. This study presents the development of the GRASP forcing data that is a hybrid of the reanalyses (ERA-40 and JRA-25) and observations. The GRASP data offer daily mean, maximum, and minimum 2 m air temperatures as well as precipitation, solar radiation, vapor pressure, and 10 m wind speed over global land areas, excluding Antarctica, for the period 1961-2010 at a grid size of 1.125°. The monthly climatologies of the variables of the GRASP data were forced to be close to those of the observations for the baseline period (1961-1990 or 1983-2005) through bias corrections. The GRASP data are intercompared with other forcing data for land surface modeling (the S06, WATCH Forcing Data, and WATCH Forcing Data Methodology Applied to ERA-Interim data). The results demonstrate that the daily minimum temperature, diurnal temperature range, vapor pressure, solar radiation, and wind speed from the GRASP data are more valuable for crop modeling than the reanalyses and other forcing data. For remaining variables, the reliability of the GRASP data is higher than that of the reanalyses and on a similar level with that of the other forcing data. The GRASP data offer accurate estimates of daily weather as the inputs for crop models, providing unique opportunities to link historical changes in climate with crop production over the last half century.

  7. Development of a combined atomic force microscopy and side-view imaging system for mechanotransduction research

    NASA Astrophysics Data System (ADS)

    Beicker, Kellie N.

    Key metrics for understanding cell response to mechanical stimuli include rearrangement of the cytoskeletal and nucleoskeletal structure, induced strains and biochemical distributions; however, structural information during applied stress is limited by our ability to image cells under load. In order to study the mechanics of single cells and subcellular components under load, I have developed a unique imaging system that combines an atomic force microscope (AFM) with both vertical light-sheet (VLS) illumination and a new imaging technique called PRISM - Pathway Rotated Imaging for Sideways Microscopy. The combined AFM and PRISM system facilitates the imaging of cell deformation in the direction of applied force with accompanying pico-Newton resolution force measurements. The additional inclusion of light-sheet microscopy improves the signal-to-noise ratio achieved by illumination of only a thin layer of the cell. This system is capable of pico-newton resolution force measurements with simultaneous side-view high frame rate imaging for single-molecule and single-cell force studies. Longer-term goals for this instrument are to investigate how external mechanical stimuli, specifically single-molecule interactions, alter gene expression, motility, and differentiation. The overall goal of my dissertation work is to design a tool useful for mechanobiology studies of single cells. This requires the design and implementation of PRISM and VLS systems that can be coupled to the standard Asylum AFM on inverted optical microscope. I also examine the strategy and implementation of experimental procedures and data analysis pipelines for single-cell and single-molecule force spectroscopy. These goals can be broken down as follows: • Performed single-molecule force spectroscopy experiments. • Performed single-cell force spectroscopy experiments. • Constructed and characterized the side-view microscopy system. • Applied combined AFM and side-vew microscopy system.

  8. An attempt to bridge muscle architecture dynamics and its instantaneous rate of force development using ultrasonography.

    PubMed

    Li, Jizhou; Zhou, Yongjin; Zheng, Yong-Ping; Li, Guanglin

    2015-08-01

    Muscle force output is an essential index in rehabilitation assessment or physical exams, and could provide considerable insights for various applications such as load monitoring and muscle assessment in sports science or rehabilitation therapy. Besides direct measurement of force output using a dynamometer, electromyography has earlier been used in several studies to quantify muscle force as an indirect means. However, its spatial resolution is easily compromised as a summation of the action potentials from neighboring motor units of electrode site. To explore an alternative method to indirectly estimate the muscle force output, and with better muscle specificity, we started with an investigation on the relationship between architecture dynamics and force output of triceps surae. The muscular architecture dynamics is captured in ultrasonography sequences and estimated using a previously reported motion estimation method. Then an indicator named as the dorsoventrally averaged motion profile (DAMP) is employed. The performance of force output is represented by an instantaneous version of the rate of force development (RFD), namely I-RFD. From experimental results on ten normal subjects, there were significant correlations between the I-RFD and DAMP for triceps surae, both normalized between 0 and 1, with the sum of squares error at 0.0516±0.0224, R-square at 0.7929±0.0931 and root mean squared error at 0.0159±0.0033. The statistical significance results were less than 0.01. The present study suggested that muscle architecture dynamics extracted from ultrasonography during contraction is well correlated to the I-RFD and it can be a promising option for indirect estimation of muscle force output.

  9. Supplement to Task Force Report on Rural Development Research in the Northeast for the Next Five Years--A Framework. Publication 1.

    ERIC Educational Resources Information Center

    Harrington, Clifford R., Comp.; Glock, Sandra, Comp.

    Prepared by the Task Force on Rural Development Research (appointed by the U.S. Department of Agriculture), this analytical directory gives primary emphasis to 133 Rural Development 1 (RD1) research projects which were "active" projects between January 1 and June 30, 1973 in 13 Northeastern state agricultural experiment stations and the…

  10. Development of a True Transition State Force Field from Quantum Mechanical Calculations.

    PubMed

    Madarász, Ádám; Berta, Dénes; Paton, Robert S

    2016-04-12

    Transition state force fields (TSFF) treated the TS structure as an artificial minimum on the potential energy surface in the past decades. The necessary parameters were developed either manually or by the Quantum-to-molecular mechanics method (Q2MM). In contrast with these approaches, here we propose to model the TS structures as genuine saddle points at the molecular mechanics level. Different methods were tested on small model systems of general chemical reactions such as protonation, nucleophilic attack, and substitution, and the new procedure led to more accurate models than the Q2MM-type parametrization. To demonstrate the practicality of our approach, transferrable parameters have been developed for Mo-catalyzed olefin metathesis using quantum mechanical properties as reference data. Based on the proposed strategy, any force field can be extended with true transition state force field (TTSFF) parameters, and they can be readily applied in several molecular mechanics programs as well.

  11. Force Sensing Resistor (FSR): a brief overview and the low-cost sensor for active compliance control

    NASA Astrophysics Data System (ADS)

    Sadun, A. S.; Jalani, J.; Sukor, J. A.

    2016-07-01

    Force Sensing Resistors (FSR) sensors are devices that allow measuring static and dynamic forces applied to a contact surface. Their range of responses is basically depending on the variation of its electric resistance. In general, Flexiforce and Interlink are two common types of FSR sensors that are available, cheap and easily found in the market. Studies have shown that the FSR sensors are usually applied for robotic grippers and for biomechanical fields. This paper provides a brief overview of the application of the FSR sensors. Subsequently, two different set of experiments are carried out to test the effectiveness of the Flexiforce and Interlink sensors. First, the hardness detector system (Case Study A) and second, the force-position control system (Case Study B). The hardware used for the experiment was developed from low-cost materials. The results revealed that both FSR sensors are sufficient and reliable to provide a good sensing modality particularly for measuring force. Apart from the low-cost sensors, essentially, the FSR sensors are very useful devices that able to provide a good active compliance control, particularly for the grasping robotic hand.

  12. 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.

  13. 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.

  14. Active Path Selection of Fluid Microcapsules in Artificial Blood Vessel by Acoustic Radiation Force

    NASA Astrophysics Data System (ADS)

    Masuda, Kohji; Muramatsu, Yusuke; Ueda, Sawami; Nakamoto, Ryusuke; Nakayashiki, Yusuke; Ishihara, Ken

    2009-07-01

    Micrometer-sized microcapsules collapse upon exposure to ultrasound. Use of this phenomenon for a drug delivery system (DDS), not only for local delivery of medication but also for gene therapy, should be possible. However, enhancing the efficiency of medication is limited because capsules in suspension diffuse in the human body after injection, since the motion of capsules in blood flow cannot be controlled. To control the behavior of microcapsules, acoustic radiation force was introduced. We detected local changes in microcapsule density by producing acoustic radiation force in an artificial blood vessel. Furthermore, we theoretically estimated the conditions required for active path selection of capsules at a bifurcation point in the artificial blood vessel. We observed the difference in capsule density at both in the bifurcation point and in alternative paths downstream of the bifurcation point for different acoustic radiation forces. Comparing the experimental results with those obtained theoretically, the conditions for active path selection were calculated from the acoustic radiation force and fluid resistance of the capsules. The possibility of controlling capsule flow towards a specific point in a blood vessel was demonstrated.

  15. Circadian force and EMG activity in hindlimb muscles of rhesus monkeys

    NASA Technical Reports Server (NTRS)

    Hodgson, J. A.; Wichayanuparp, S.; Recktenwald, M. R.; Roy, R. R.; McCall, G.; Day, M. K.; Washburn, D.; Fanton, J. W.; Kozlovskaya, I.; Edgerton, V. R.; Rumbaugh, D. M. (Principal Investigator)

    2001-01-01

    Continuous intramuscular electromyograms (EMGs) were recorded from the soleus (Sol), medial gastrocnemius (MG), tibialis anterior (TA), and vastus lateralis (VL) muscles of Rhesus during normal cage activity throughout 24-h periods and also during treadmill locomotion. Daily levels of MG tendon force and EMG activity were obtained from five monkeys with partial datasets from three other animals. Activity levels correlated with the light-dark cycle with peak activities in most muscles occurring between 08:00 and 10:00. The lowest levels of activity generally occurred between 22:00 and 02:00. Daily EMG integrals ranged from 19 mV/s in one TA muscle to 3339 mV/s in one Sol muscle: average values were 1245 (Sol), 90 (MG), 65 (TA), and 209 (VL) mV/s. The average Sol EMG amplitude per 24-h period was 14 microV, compared with 246 microV for a short burst of locomotion. Mean EMG amplitudes for the Sol, MG, TA, and VL during active periods were 102, 18, 20, and 33 microV, respectively. EMG amplitudes that approximated recruitment of all fibers within a muscle occurred for 5-40 s/day in all muscles. The duration of daily activation was greatest in the Sol [151 +/- 45 (SE) min] and shortest in the TA (61 +/- 19 min). The results show that even a "postural" muscle such as the Sol was active for only approximately 9% of the day, whereas less active muscles were active for approximately 4% of the day. MG tendon forces were generally very low, consistent with the MG EMG data but occasionally reached levels close to estimates of the maximum force generating potential of the muscle. The Sol and TA activities were mutually exclusive, except at very low levels, suggesting very little coactivation of these antagonistic muscles. In contrast, the MG activity usually accompanied Sol activity suggesting that the MG was rarely used in the absence of Sol activation. The results clearly demonstrate a wide range of activation levels among muscles of the same animal as well as among different

  16. Increase in Mechanical Resistance to Force in a Shear-Activated Protein

    NASA Astrophysics Data System (ADS)

    Botello, Eric; Harris, Nolan; Choi, Huiwan; Zhou, Zhou; Bergeron, Angela; Dong, Jing-Fei; Kiang, Ching-Hwa

    2009-03-01

    von Willebrand factor (VWF) is the largest multimeric adhesion ligand found in human blood. Plasma VWF (pVWF) must be exposed to shear stress, like at sites of vascular injury, to be activated to bind platelets to induce blood clotting. In addition, adhesion activity of VWF is related to its polymer size, with the ultra-large form of VWF (ULVWF) being hyper-active, and forming fibers even without exposure to shear stress. We used the AFM to stretch pVWF, sheared VWF (sVWF) and ULVWF, and monitor the forces as a function of molecular extension. We showed a similar increase in force resistance to unfolding for sVWF and ULVWF when compared to pVWF. The increase in force is reduced when other molecules that are known to disrupt their fibril formation are present. Our results provide evidence that the common higher order structure of sVWF and ULVWF may affect the domain structure that causes difference in their adhesion activity compared to pVWF.

  17. Differences in typing forces, muscle activity, comfort, and typing performance among virtual, notebook, and desktop keyboards.

    PubMed

    Kim, Jeong Ho; Aulck, Lovenoor; Bartha, Michael C; Harper, Christy A; Johnson, Peter W

    2014-11-01

    The present study investigated whether there were physical exposure and typing productivity differences between a virtual keyboard with no tactile feedback and two conventional keyboards where key travel and tactile feedback are provided by mechanical switches under the keys. The key size and layout were same across all the keyboards. Typing forces; finger and shoulder muscle activity; self-reported comfort; and typing productivity were measured from 19 subjects while typing on a virtual (0 mm key travel), notebook (1.8 mm key travel), and desktop keyboard (4 mm key travel). When typing on the virtual keyboard, subjects typed with less force (p's < 0.0001) and had lower finger flexor/extensor muscle activity (p's < 0.05). However, the lower typing forces and finger muscle activity came at the expense of a 60% reduction in typing productivity (p < 0.0001), decreased self-reported comfort (p's < 0.0001), and a trend indicating an increase in shoulder muscle activity (p's < 0.10). Therefore, for long typing sessions or when typing productivity is at a premium, conventional keyboards with tactile feedback may be more suitable interface.

  18. 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.

  19. The Children Are Waiting. The Report of the Early Childhood Development Task Force.

    ERIC Educational Resources Information Center

    Early Childhood Development Task Force, New York, NY.

    The Task Force on Early Childhood Development for New York City examined early childhood services and explored the feasibility of establishing an office for early childhood services. This report assesses the effectiveness of early childhood services in meeting the needs of children and their parents and recommends changes in the quantity and…

  20. Women in the Work Force: Development and Field Testing of Curriculum Materials. Final Report.

    ERIC Educational Resources Information Center

    Vetter, Louise; Sethney, Barbara J.

    To aid girls in considering future alternatives and making plans for labor force participation and adult female roles, curriculum materials and associated measures of knowledge, attitudes, and plans were developed and pilot tested with 100 girls in Grades 7, 9, and 11. Materials and measures were revised on the basis of pilot test data, including…

  1. Development and Standardization of the Air Force Officer Qualifying Test Form L.

    ERIC Educational Resources Information Center

    Miller, Robert E.

    In accordance with the normal replacement cycle, a new form of the Air Force Officer Qualifying Test (AFOQT) was developed for implementation in Fiscal Year 1972. The new form is designated Form L. It resembles other recent forms in type of content, organization, and norming strategy. Like other forms, it yields pilot, navagation-technical,…

  2. 76 FR 21090 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-14

    .... The Task Force is established pursuant to Executive Order 13540 and focused on coordinating the efforts of Federal agencies to improve capital, business development opportunities and pre-established... later than one year after its first meeting, a report on the performance of its functions and...

  3. The Symbiotic Relationship between the Air Force’s Active and Reserve Components: Ensuring the Health of the Total Force

    DTIC Science & Technology

    2013-02-01

    inefficiencies drive higher costs and may ultimately imperil our ability to perform the national defense mission. If we properly address the symbiotic...thresholds and tipping points to draw a line beyond which the health of the total force finds itself at risk. Maintaining higher RC experience levels is...schedule, and other performance goals.45 Moreover, the matrix incorporates qualitative factors such as leader- ship, total force education , the triad

  4. 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

  5. Effects of fast-velocity eccentric resistance training on early and late rate of force development.

    PubMed

    Oliveira, Anderson Souza; Corvino, Rogério Bulhões; Caputo, Fabrizio; Aagaard, Per; Denadai, Benedito Sérgio

    2016-01-01

    This study examined whether short-term maximal resistance training employing fast-velocity eccentric knee extensor actions would induce improvements in maximal isometric torque and rate of force development (RFD) at early (<100 ms) and late phases (>100 ms) of rising torque. Twenty healthy men were assigned to two experimental groups: eccentric resistance training (TG) or control (CG). Participants on the TG trained three days a week for a total of eight weeks. Training consisted of maximal unilateral eccentric knee extensors actions performed at 180 °s-1. Maximal isometric knee extensor torque (MVC) and incremental RFD in successive 50 ms time-windows from the onset contraction were analysed in absolute terms (RFDINC) or when normalised relative to MVC (RFDREL). After eight weeks, TG demonstrated increases in MVC (28%), RFDINC (0-50 ms: 30%; 50-100 ms: 31%) and RFDREL (0-50 ms: 29%; 50-100 ms: 32%). Moreover, no changes in the late phase of incremental RFD were observed in TG. No changes were found in the CG. In summary, we have demonstrated, in active individuals, that a short period of resistance training performed with eccentric fast-velocity isokinetic muscle contractions is able to enhance RFDINC and RFDREL obtained at the early phase of rising joint torque.

  6. The Possible Effects of Potential Key Technological Developments on the Force Structure of the Australian Army in 2040

    DTIC Science & Technology

    2014-12-01

    unlikely to be significant enough to effect force structures . Metal , ceramic and composite armours are likely to remain heavy and bulky. Even techniques...UNCLASSIFIED UNCLASSIFIED The Possible Effects of Potential Key Technological Developments on the Force Structure of the Australian...undertaken focussing on impacts to force structures . A modified TOWS (Threats, Opportunities, Weaknesses & Strengths) technique was applied to eleven

  7. Development of OPLS-AA Force Field Parameters for 68 Unique Ionic Liquids.

    PubMed

    Sambasivarao, Somisetti V; Acevedo, Orlando

    2009-04-14

    OPLS-AA force field parameters have been developed and validated for use in the simulation of 68 unique combinations of room temperature ionic liquids featuring 1-alkyl-3-methylimidazolium [RMIM] (R = Me, Et, Bu, Hex, Oct), N-alkylpyridinium [RPyr], and choline cations, along with Cl(-), PF6(-), BF4(-), NO3(-), AlCl4(-), Al2Cl7(-), TfO(-), saccharinate, and acesulfamate anions. The new parameters were fit to conformational profiles from gas-phase ab initio calculations at the LMP2/cc-pVTZ(-f)//HF/6-31G(d) theory level and compared to experimental condensed-phase structural and thermodynamic data. Monte Carlo simulations of the ionic liquids gave relative deviations from experimental densities of ca. 1-3% at 25 °C for most combinations and also yielded close agreement over a temperature range of 5 to 90 °C. Predicted heats of vaporization compared well with available experimental data and estimates. Transferability of the new parameters to multiple alkyl side-chain lengths for [RMIM] and [RPyr] was determined to give excellent agreement with charges and torsion potentials developed specific to desired alkyl lengths in 35 separate ionic liquid simulations. As further validation of the newly developed parameters, the Kemp elimination reaction of benzisoxazole via piperidine was computed in 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6] using mixed quantum and molecular mechanics (QM/MM) simulations and was found to give close agreement with the experimental free energy of activation.

  8. Malaria Vaccine Development and How External Forces Shape It: An Overview

    PubMed Central

    Lorenz, Veronique; Karanis, Gabriele; Karanis, Panagiotis

    2014-01-01

    The aim of this paper is to analyse the current status and scientific value of malaria vaccine approaches and to provide a realistic prognosis for future developments. We systematically review previous approaches to malaria vaccination, address how vaccine efforts have developed, how this issue may be fixed, and how external forces shape vaccine development. Our analysis provides significant information on the various aspects and on the external factors that shape malaria vaccine development and reveal the importance of vaccine development in our society. PMID:24983392

  9. [Unpredictable chronic mild stress effects on antidepressants activities in forced swim test].

    PubMed

    Kudryashov, N V; Kalinina, T S; Voronina, T A

    2015-02-01

    The experiments has been designed to study unpredictable chronic mild stress effect on anti-depressive activities of amitriptyline (10 mg/kg) and fluoxetine (20 mg/kg) in forced swim test in male outbred mice. It is shown that acute treatment with fluoxetine does not produce any antidepressant effects in mice following stress of 14 days while the sub-chronic injections of fluoxetine result in more deep depressive-like behavior. In 28 daily stressed mice, antidepressant effect of fluoxetine is observed independently of the injection rates. Amitriptyline demonstrates the antidepressant activity regardless of the duration of stress or administration scheduling, but at the same time the severity of anti-immobilization effect of amitriptyline in stressed mice is weaker in compare to non-stressed trails. Thus, the injection rates and duration of unpredictable mild chronic stress are the parameters that determine the efficiency of antidepressants in the mouse forced swimming test.

  10. A review of Air Force high efficiency cascaded multiple bandgap solar cell research and development

    NASA Technical Reports Server (NTRS)

    Rahilly, W. P.

    1979-01-01

    At the time of their conception, the cell stack systems to be discussed represent the best semiconductor materials combinations to achieve Air Force program goals. These systems are investigated thoroughly and the most promising systems, from the standpoint of high efficiency, are taken for further development with large area emphasized (at least 4 sq cm). The emphasis in the Air Force cascaded cell program is placed on eventual nonconcentrator application. This use of the final cell design considerably relieves the low resistance requirements for the tunnel junction. In a high concentration application the voltage drop across the tunnel junction can be a very serious problem.

  11. Encoding of forelimb forces by corticospinal tract activity in the rat

    PubMed Central

    Guo, Yi; Foulds, Richard A.; Adamovich, Sergei V.; Sahin, Mesut

    2014-01-01

    In search of a solution to the long standing problems encountered in traditional brain computer interfaces (BCI), the lateral descending tracts of the spinal cord present an alternative site for taping into the volitional motor signals. Due to the convergence of the cortical outputs into a final common pathway in the descending tracts of the spinal cord, neural interfaces with the spinal cord can potentially acquire signals richer with volitional information in a smaller anatomical region. The main objective of this study was to evaluate the feasibility of extracting motor control signals from the corticospinal tract (CST) of the rat spinal cord. Flexible substrate, multi-electrode arrays (MEA) were implanted in the CST of rats trained for a lever pressing task. This novel use of flexible substrate MEAs allowed recording of CST activity in behaving animals for up to three weeks with the current implantation technique. Time-frequency and principal component analyses (PCA) were applied to the neural signals to reconstruct isometric forelimb forces. Computed regression coefficients were then used to predict isometric forces in additional trials. The correlation between measured and predicted forces in the vertical direction averaged across six animals was 0.67 and R2 value was 0.44. Force regression in the horizontal directions was less successful, possibly due to the small amplitude of forces. Neural signals above and near the high gamma band made the largest contributions to prediction of forces. The results of this study support the feasibility of a spinal cord computer interface (SCCI) for generation of command signals in paralyzed individuals. PMID:24847198

  12. Development of the force-feedback model for an epidural needle insertion simulator.

    PubMed

    Hiemenz, L; Stredney, D; Schmalbrock, P

    1998-01-01

    The Ohio Supercomputer Center and the Department of Anesthesiology at the OSU Medical Center have developed a computer-based simulation system for use in training anesthesiology residents in the technique of placing a needle for an epidural block. Although the simulator has been well regarded, the fidelity of the haptic feedback is limited because it is based on subjective expert-user evaluation and not on objective model-based or data-based empirical methods. Only a single degree of freedom for force-feedback is required. However, the simulation must be able to accurately portray the force required to puncture each layer of tissue in order to feel realistic. The purpose of the research described in this paper was to devise a methodology for creating empirically based realistic force-feedback models for the epidural needle insertion procedure using MRI data and biomechanical data from materials testing.

  13. Magnetic force driven six degree-of-freedom active vibration isolation system using a phase compensated velocity sensor

    SciTech Connect

    Kim, Yongdae; Park, Kyihwan; Kim, Sangyoo

    2009-04-15

    A six-axis active vibration isolation system (AVIS) is developed using voice coil actuators. Point contact configuration is employed to have an easy assembly of eight voice coil actuators to an upper and a base plates. The velocity sensor, using an electromagnetic principle that is commonly used in the vibration control, is investigated since its phase lead characteristic causes an instability problem for a low frequency vibration. The performances of the AVIS are investigated in the frequency domain and finally validated by comparing with the passive isolation system using the atomic force microscope images.

  14. Calcium-activated force responses in fast- and slow-twitch skinned muscle fibres of the rat at different temperatures.

    PubMed Central

    Stephenson, D G; Williams, D A

    1981-01-01

    1. Force responses from mechanically skinned fibres of rat skeletal muscles (extensor digitorum longus and soleus) were measured at different temperatures in the range 3-35 degrees C following sudden changes in Ca2+ concentration in the preparations. 2. At all temperatures there were characteristic differences between the slow- and fast-twitch muscle fibres with respect to the relative steady-state force-[Ca2+] relation: such as a lower [Ca2+] threshold for activation and a less steep force-pCa curve in slow-twitch muscle fibres. 3. At 3-5 degrees C the force changes in both types of muscle fibres lagged considerably behind the estimated changes in [Ca2+] within the preparations and this enabled us to perform a comparative analysis of the Ca2+ kinetics in the process of force development in both muscle fibre types. This analysis suggest that two and six Ca2+ ions are involved in the regulatory unit for contraction of slow- and fast-twitch muscle fibres respectively. 4. The rate of relaxation following a sudden decrease in [Ca2+] was much lower in the slow-twitch than in the fast-twitch muscle at 5 degrees C, suggesting that properties of the contractile apparatus could play an essential role in determining the rate of relaxation in vivo. 5. There was substantial variation in Ca2+ sensitivity between muscle fibres of the same type from different animals at each temperature. However the steepness of the force-[Ca2+] relation was essentially the same for all fibres of the same type. 6. A change in temperature from 5 to 25 degrees C had a statistically significant effect on the sensitivity of the fast-twitch muscle fibres, rendering them less sensitive to Ca2+ by a factor of 2. However a further increase in temperature from 25 to 35 degrees C did not have any statistically significant effect on the force-[Ca2+] relation in fast-twitch muscle fibres. 7. The effect of temperature on the Ca2+ sensitivity of slow-twitch muscle fibres was not statistically significant

  15. Design and Development of a Flapping Wing System for Unsteady Forces and Power Measurement

    NASA Astrophysics Data System (ADS)

    Mudbhari, Durlav

    Flyers and swimmers flap their wings and fins to propel themselves efficiently over long distances, maneuver in tight spaces and navigate silently to avoid detection by prey. A key element to achieve these amazing feats is the flexibility of their propulsors. While numerous studies have shown that homogeneously flexible wings can enhance force production and efficiency, animals actually have wings with varying flexural rigidity along their chord and span. The goal of this study is to design and develop an experimental setup that would help understand and characterize the force production and energetics of functionally-graded, chordwise flexible wings. A flapping wing composed of a rigid and a flexible region, that define a chordwise gradient in flexural rigidity, is used to model functionally-graded materials. By varying the ratio of the lengths of the rigid to flexible regions, the flexural rigidity of the flexible region, and the flapping frequency, the thrust production of a functionally-graded wing is directly measured. An unsteady force and torque measurement system is developed to measure the lift/drag forces and power consumption during flapping wing flight in wind tunnel. A novel vacuum chamber apparatus is developed to be used in conjunction with the wind tunnel measurements to reliably measure the aerodynamic power input and the propulsive efficiency.

  16. Iterative weighted average diffusion as a novel external force in the active contour model

    NASA Astrophysics Data System (ADS)

    Mirov, Ilya S.; Nakhmani, Arie

    2016-03-01

    The active contour model has good performance in boundary extraction for medical images; particularly, Gradient Vector Flow (GVF) active contour model shows good performance at concavity convergence and insensitivity to initialization, yet it is susceptible to edge leaking, deep and narrow concavities, and has some issues handling noisy images. This paper proposes a novel external force, called Iterative Weighted Average Diffusion (IWAD), which used in tandem with parametric active contours, provides superior performance in images with high values of concavity. The image gradient is first turned into an edge image, smoothed, and modified with enhanced corner detection, then the IWAD algorithm diffuses the force at a given pixel based on its 3x3 pixel neighborhood. A forgetting factor, φ, is employed to ensure that forces being spread away from the boundary of the image will attenuate. The experimental results show better behavior in high curvature regions, faster convergence, and less edge leaking than GVF when both are compared to expert manual segmentation of the images.

  17. When forced fabrications become truth: causal explanations and false memory development.

    PubMed

    Chrobak, Quin M; Zaragoza, Maria S

    2013-08-01

    Studies of text comprehension have amply demonstrated that when reading a story, people seek to identify the causal and motivational forces that drive the interactions of characters and link events (e.g., Zwaan, Langston, & Graesser, 1995), thereby achieving explanatory coherence. In the present study we provide the first evidence that the search for explanatory coherence also plays a role in the memory errors that result from suggestive forensic interviews. Using a forced fabrication paradigm (e.g., Chrobak & Zaragoza, 2008), we conducted 3 experiments to test the hypothesis that false memory development is a function of the explanatory role these forced fabrications served (the explanatory role hypothesis). In support of this hypothesis, participants were more likely to subsequently freely report (Experiment 1) and falsely assent to (Experiment 2) their forced fabrications when they helped to provide a causal explanation for a witnessed outcome than when they did not serve this explanatory role. Participants were also less likely to report their forced fabrications when their explanatory strength had been reduced by the presence of an alternative explanation that could explain the same outcome as their fabrication (Experiment 3). These findings extend prior research on narrative and event comprehension processes by showing that the search for explanatory coherence can continue for weeks after the witnessed event is initially perceived, such that causally relevant misinformation from subsequent interviews is, over time, incorporated into memory for the earlier witnessed event.

  18. Development of An Automatic Approaching System for Electrochemical Nanofabrication Using Visual and Force-Displacement Sensing

    PubMed Central

    Lai, Lei-Jie; Zhou, Shi-Yu; Gu, Guo-Ying; Zhu, Li-Min

    2012-01-01

    In this paper, a fast automatic precision approaching system is developed for electrochemical nanofabrication using visual and force-displacement sensing. Before the substrate is fabricated, the template should approach the substrate accurately to establish the initial gap between the template and substrate. During the approaching process, the template is first quickly moved towards the substrate by the stepping motor until a specified gap is detected by the visual feedback. Then, the successive approach using the switch of macro-micro motion with a force-displacement sensing module is triggered to make the template contact with the substrate to nanometre accuracy. The contact force is measured by the force-displacement sensing module which employs the high-resolution capacitive displacement sensor and flexure compliant mechanism. The high sensitivity of this capacitive displacement sensor ensures high accuracy of the template-substrate contact. The experimental results show that the template can reach the substrate accurately and smoothly, which verifies the effectiveness of the proposed approaching system with the visual and the force-displacement sensing modules. PMID:23012500

  19. Development of a surgical instrument for measuring forces applied to the ossicles of the middle ear.

    PubMed

    Sheedy, Michael; Bergin, Mike; Wylie, Grant; Ross, Peter; Dove, Richard; Bird, Phil

    2012-12-01

    Surgery of the middle ear is a delicate process that requires the surgeon to manipulate the ossicles, the smallest bones in the body. Excessive force applied to the ossicles can easily be transmitted through to the inner ear which may cause a permanent sensorineural hearing loss. An instrument was required to measure the forces applied to cadaveric temporal bone ossicles with the vision of measuring forces in vivo at a later stage. A feasibility study was conducted to investigate a method of measuring force and torque applied to the ossicles of the middle ear. Information from research papers was gathered to determine the expected amplitudes. The study looked at commercially available transducers as well as constructing an instrument using individual axis transducers coupled together. A prototype surgical instrument was constructed using the ATI industrial automation Nano17 six axis transducer. The Nano17 allows for the measurement of force and torque in the X, Y and Z axis to a resolution of 1/320 N. The use of the Nano17 enabled rapid development of the surgical instrument. It meets the requirements for its use on cadaveric models and has the potential to be a useful data collection tool in vivo.

  20. Effect of extensor muscle activation on the response to lumbar posteroanterior forces.

    PubMed

    Lee, M; Esler, M A; Mildren, J; Herbert, R

    1993-05-01

    The purpose of this study was to examine the responses of normal subjects to the application of cyclical lumbar posteroanterior forces which simulated a manipulative therapy technique known as mobilization. The specific aim was to determine whether increases in spinal extensor muscle activity could modify the stiffness of lumbar posteroanterior movements. The lumbar posteroanterior stiffness was measured in eleven asymptomatic subjects in the prone position, both in the relaxed condition and during maximal voluntary isometric muscle contractions. The electromyographic activity of lumbar extensor muscles was measured in the relaxed and maximal contraction conditions during the application of mobilization. The posteroanterior stiffness was found to be significantly greater during maximum activation of the extensor muscles. The results indicate that muscle activity can significantly alter lumbar posteroanterior stiffness. Clinicians often apply posteroanterior forces over a spinous process of a vertebra to assess the resistance to movement. Information about the degree and nature of perceived resistance to posteroanterior movement is used to help make a diagnosis and select treatment techniques. This study has shown that increased activity of the spinal extensor muscles can increase the stiffness of lumbar posteroanterior movements, compared with the case where the subject is relaxed. When interpreting the posteroanterior responses of patients, clinicians should be aware that spinal extensor mucle activity can influence resistance to posteroanterior movement.

  1. Environmental Assessment, Wing Infrastructure Development Outlook (WINDO) Implementation Plan (FY 04-06). Volume 1, Beale Air Force Base, California

    DTIC Science & Technology

    2005-07-01

    Environmental Assessment Wing Infrastructure Development Outlook (WINDO) Implementation Plan (FY 04-06) Volume 1 Beale Air Force Base, California ...Development Outlook (WINDO) Implementation Plan (FY 04-06) Volume 1 Beale Air Force Base, California 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM...THE PROPOSED ACTION Wing Infrastructure Development Outlook (WINDO) Implementation Plan at Beale Air Force Base (AFB), California : Volume 1

  2. Defence force activities in marine protected areas: environmental management of Shoalwater Bay Training Area, Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Wu, Wen; Wang, Xiaohua; Paull, David; Kesby, Julie

    2010-05-01

    Environmental management of military activities is of growing global concern by defence forces. As one of the largest landholders in Australia, the Australian Defence Force (ADF) is increasingly concerned with sustainable environmental management. This paper focuses on how the ADF is maintaining effective environmental management, especially in environmentally sensitive marine protected areas. It uses Shoalwater Bay Training Area (SWBTA) as a research example to examine environmental management strategies conducted by the ADF. SWBTA is one of the most significant Defence training areas in Australia, with a large number of single, joint and combined military exercises conducted in the area. With its maritime component contained in the Great Barrier Reef Marine Park (GBRMP), the Great Barrier Reef World Heritage Area (GBRWHA), and abutting Queensland’s State Marine Parks, it has high protection values. It is therefore vital for the ADF to adopt environmentally responsible management while they are conducting military activities. As to various tools employed to manage environmental performance, the ISO 14001 Environmental Management System (EMS) is widely used by the ADF. This paper examines military activities and marine environmental management within SWBTA, using the Talisman Saber (TS) exercise series as an example. These are extensive joint exercises conducted by the ADF and the United States defence forces. The paper outlines relevant legislative framework and environmental policies, analyses how the EMS operates in environmental management of military activities, and how military activities comply with these regulations. It discusses the implementation of the ADF EMS, including risk reduction measures, environmental awareness training, consultation and communication with stakeholders. A number of environmental management actions used in the TS exercises are presented to demonstrate the EMS application. Our investigations to this point indicate that the ADF is

  3. Soleus Fiber Force and Maximal Shortening Velocity After Non-Weight Bearing with Intermittent Activity

    NASA Technical Reports Server (NTRS)

    Widrick, Jeffrey J.; Bangart, Jill J.; Karhanek, Miloslav; Fitts, Robert H.

    1996-01-01

    This study examined the effectiveness of intermittent weight bearing (IWB) as a countermeasure to non-weight-bearing (NWB)-induced alterations in soleus type 1 fiber force (in mN), tension (P(sub o); force per fiber cross-sectional area in kN/sq m), and maximal unloaded shortening velocity (V(sub o), in fiber lengths/s). Adult rats were assigned to one of the following groups: normal weight bearing (WB), 14 days of hindlimb NWB (NWB group), and 14 days of hindlimb NWB with IWB treatments (IWB group). The IWB treatment consisted of four 10-min periods of standing WB each day. Single, chemically permeabilized soleus fiber segments were mounted between a force transducer and position motor and were studied at maximal Ca(2+) activation, after which type 1 fiber myosin heavy-chain composition was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. NWB resulted in a loss in relative soleus mass (-45%), with type 1 fibers displaying reductions in diameter (-28%) and peak isometric force (-55%) and an increase in V(sub o) (+33%). In addition, NWB induced a 16% reduction in type 1 fiber P., a 41% reduction in type 1 fiber peak elastic modulus [E(sub o), defined as ((delta)force/(delta)length x (fiber length/fiber cross-sectional area] and a significant increase in the P(sub o)/E(sub o) ratio. In contrast to NWB, IWB reduced the loss of relative soleus mass (by 22%) and attenuated alterations in type 1 fiber diameter (by 36%), peak force (by 29%), and V(sub o)(by 48%) but had no significant effect on P(sub o), E(sub o) or P(sub o)/E(sub o). These results indicate that a modest restoration of WB activity during 14 days of NWB is sufficient to attenuate type 1 fiber atrophy and to partially restore type 1 peak isometric force and V(sub o) to WB levels. However, the NWB-induced reductions in P(sub o) and E(sub o) which we hypothesize to be due to a decline in the number and stiffness of cross bridges, respectively, are considerably less responsive to this

  4. Evaluation of EMG, force and joystick as control interfaces for active arm supports

    PubMed Central

    2014-01-01

    Background The performance capabilities and limitations of control interfaces for the operation of active movement-assistive devices remain unclear. Selecting an optimal interface for an application requires a thorough understanding of the performance of multiple control interfaces. Methods In this study the performance of EMG-, force- and joystick-based control interfaces were assessed in healthy volunteers with a screen-based one-dimensional position-tracking task. The participants had to track a target that was moving according to a multisine signal with a bandwidth of 3 Hz. The velocity of the cursor was proportional to the interface signal. The performance of the control interfaces were evaluated in terms of tracking error, gain margin crossover frequency, information transmission rate and effort. Results None of the evaluated interfaces was superior in all four performance descriptors. The EMG-based interface was superior in tracking error and gain margin crossover frequency compared to the force- and the joystick-based interfaces. The force-based interface provided higher information transmission rate and lower effort than the EMG-based interface. The joystick-based interface did not present any significant difference with the force-based interface for any of the four performance descriptors. We found that significant differences in terms of tracking error and information transmission rate were present beyond 0.9 and 1.4 Hz respectively. Conclusions Despite the fact that the EMG-based interface is far from the natural way of interacting with the environment, while the force-based interface is closer, the EMG-based interface presented very similar and for some descriptors even a better performance than the force-based interface for frequencies below 1.4 Hz. The classical joystick presented a similar performance to the force-based interface and holds the advantage of being a well established interface for the control of many assistive devices. From these

  5. Evaluation of uncertainty in experimental active buckling control of a slender beam-column with disturbance forces using Weibull analysis

    NASA Astrophysics Data System (ADS)

    Enss, Georg C.; Platz, Roland

    2016-10-01

    Buckling of slender load-bearing beam-columns is a crucial failure scenario in light-weight structures as it may result in the collapse of the entire structure. If axial load and load capacity are unknown, stability becomes uncertain. To compensate this uncertainty, the authors successfully developed and evaluated an approach for active buckling control for a slender beam-column, clamped at the base and pinned at the upper end. Active lateral forces are applied with two piezoelectric stack actuators in opposing directions near the beam-column' clamped base to prevent buckling. A Linear Quadratic Regulator is designed and implemented on the experimental demonstrator and statistical tests are conducted to prove effectivity of the active approach. The load capacity of the beam-column could be increased by 40% and scatter of buckling occurrences for increasing axial loads is reduced. Weibull analysis is used to evaluate the increase of the load capacity and its related uncertainty compensation.

  6. Cancer cachexia: physical activity and muscle force in tumour-bearing rats.

    PubMed

    Toledo, Míriam; Busquets, Sílvia; Sirisi, Sònia; Serpe, Roberto; Orpí, Marcel; Coutinho, Joana; Martínez, Raquel; López-Soriano, Francisco J; Argilés, Josep M

    2011-01-01

    Rats bearing the Yoshida AH-130 ascites hepatoma are subjected to substantial weight loss, which is accompanied by anorexia at the end of the tumour cycle. Total physical activity (measured using the IR Actimeter system and Actitrack software) was determined during 11 days in control and tumour-bearing animals, skeletal muscle strength being also by the grip-strength test. The results presented clearly show that the presence of the tumour induces an earlier decrease in physical performance, which affects both skeletal muscle force and physical activity (both locomotor movements and stereotyped movements and distance travelled, among others parameters).

  7. Intercountry comparisons of labor force trends and of related developments: an overview.

    PubMed

    Mincer, J

    1985-01-01

    This paper is a survey of analyses of women's labor force growth in 12 industrialized countries, presented at a conference in Sussex, England in 1983. The main focus is on growth of the labor force of married women from 1960-1980; trends in fertility, wages, and family instability are discussed. In all countries, wages of women were lower than wages of men, although between 1960 and 1980 labor force rates of married women rose in most of the industrialized countries. 2 factors that are associated with this growth are declines in fertility and increases in divorce rates. The 12 countries studied are: 1) Australia, 2) Britain, 3) France, 4) Germany, 5) Israel, 6) Italy, 7) Japan, 8) Netherlands, 9) Spain, 10) Sweden, 11) US, and 12) USSR. The substitution variables (wages of women or their education) have strong positive effects on labor force participation in most cases, and in most cases the positive wage elasticities exceed the negative income elasticities by a sizable margin. A summary table estimating parameters of the P-function for each country, and their predictive performance in time series, are included. From 1960-1980 the average per country growth in participation of married women was 2.84% per year. Wages of working women, in this same period grew, on average, faster than wages of men in most countries, in part due to selectivity by education in labor force growth. While growth rates of real wages across countries have a weak relation with the differential growth rates of married women's labor force, the relation is strong when country parameters are taken into account. The dominance of the "discouraged" over the "added" workers in female labor force growth appears to be upheld internationally. On the average, total fertility rate dropped from 2.42 in 1970 to 1.85 in 1980. Both fertility declines and the growth of family instability appear to represent lagged effects of longer term developments in the labor force of women. Women's wages are lower than

  8. Astronomy for a Better World: IAU Office of Astronomy for Development Activities to Grow and Advance Astronomy Education and Research at Universities in the Developing World

    NASA Astrophysics Data System (ADS)

    Guinan, Edward F.; Kolenberg, Katrien

    2016-10-01

    In 2012, the International Astronomical Union (IAU), through its Office of Astronomy for Development (OAD), established the three Task Forces which drive global activities using astronomy as a tool to stimulate development. These Task Forces are: (i) Astronomy for Universities and Research; (ii) Astronomy for Children and Schools; and (iii) Astronomy for the Public.

  9. The back compressive forces during maximal push-pull activities in the sagittal plane.

    PubMed

    Kumar, S

    1994-12-01

    Ten normal young male and ten normal young female subjects (each group with a mean age of 21.1 years) performed isometric and isokinetic (50 cm per second) push and pull activity at 35 cm, 100 cm and 150 cm heights. The subjects were placed on a specially designed subject-stabilizing-platform to stabilize their lower extremities. Horizontal push-pull forces were exerted through a friction-reduced rod and sleeve assembly attached to the modified Static Dynamic Strength Tester. The strength measured by a SM 500 load cell was fed to an IBM XT through an A to D converter. The postural records were made on a videotape. The posture and strength were synchronized through an external light signal. The strength for pull activities was higher than the corresponding push activities (p < 0.01). The isometric strengths were significantly higher than the isokinetic strengths (p < 0.01). Though the push strengths were significantly lower than the pull strength, the low-back compressive forces for the push activities were 129% to 627% of the corresponding pull conditions. It is concluded that the push activities are more hazardous due to the higher magnitude of compressive load and their faster contribution to the threshold level of cumulative load leading to the precipitation of injuries.

  10. Explicit polarization: a quantum mechanical framework for developing next generation force fields.

    PubMed

    Gao, Jiali; Truhlar, Donald G; Wang, Yingjie; Mazack, Michael J M; Löffler, Patrick; Provorse, Makenzie R; Rehak, Pavel

    2014-09-16

    Conspectus Molecular mechanical force fields have been successfully used to model condensed-phase and biological systems for a half century. By means of careful parametrization, such classical force fields can be used to provide useful interpretations of experimental findings and predictions of certain properties. Yet, there is a need to further improve computational accuracy for the quantitative prediction of biomolecular interactions and to model properties that depend on the wave functions and not just the energy terms. A new strategy called explicit polarization (X-Pol) has been developed to construct the potential energy surface and wave functions for macromolecular and liquid-phase simulations on the basis of quantum mechanics rather than only using quantum mechanical results to fit analytic force fields. In this spirit, this approach is called a quantum mechanical force field (QMFF). X-Pol is a general fragment method for electronic structure calculations based on the partition of a condensed-phase or macromolecular system into subsystems ("fragments") to achieve computational efficiency. Here, intrafragment energy and the mutual electronic polarization of interfragment interactions are treated explicitly using quantum mechanics. X-Pol can be used as a general, multilevel electronic structure model for macromolecular systems, and it can also serve as a new-generation force field. As a quantum chemical model, a variational many-body (VMB) expansion approach is used to systematically improve interfragment interactions, including exchange repulsion, charge delocalization, dispersion, and other correlation energies. As a quantum mechanical force field, these energy terms are approximated by empirical functions in the spirit of conventional molecular mechanics. This Account first reviews the formulation of X-Pol, in the full variationally correct version, in the faster embedded version, and with systematic many-body improvements. We discuss illustrative examples

  11. Explicit Polarization: A Quantum Mechanical Framework for Developing Next Generation Force Fields

    PubMed Central

    2015-01-01

    Conspectus Molecular mechanical force fields have been successfully used to model condensed-phase and biological systems for a half century. By means of careful parametrization, such classical force fields can be used to provide useful interpretations of experimental findings and predictions of certain properties. Yet, there is a need to further improve computational accuracy for the quantitative prediction of biomolecular interactions and to model properties that depend on the wave functions and not just the energy terms. A new strategy called explicit polarization (X-Pol) has been developed to construct the potential energy surface and wave functions for macromolecular and liquid-phase simulations on the basis of quantum mechanics rather than only using quantum mechanical results to fit analytic force fields. In this spirit, this approach is called a quantum mechanical force field (QMFF). X-Pol is a general fragment method for electronic structure calculations based on the partition of a condensed-phase or macromolecular system into subsystems (“fragments”) to achieve computational efficiency. Here, intrafragment energy and the mutual electronic polarization of interfragment interactions are treated explicitly using quantum mechanics. X-Pol can be used as a general, multilevel electronic structure model for macromolecular systems, and it can also serve as a new-generation force field. As a quantum chemical model, a variational many-body (VMB) expansion approach is used to systematically improve interfragment interactions, including exchange repulsion, charge delocalization, dispersion, and other correlation energies. As a quantum mechanical force field, these energy terms are approximated by empirical functions in the spirit of conventional molecular mechanics. This Account first reviews the formulation of X-Pol, in the full variationally correct version, in the faster embedded version, and with systematic many-body improvements. We discuss illustrative

  12. Development of a Force Measurement Device for Lower-Body Muscular Strength Measuring of Skaters

    NASA Astrophysics Data System (ADS)

    Kim, Dong Ki; Lee, Jeong Tae

    This paper presents a force measurement system that can measure a lower-body muscular strength of skaters. The precise measurement and analysis of the left and right lower-body strength of skaters is necessary, because a left/right lower-body strength balance is helpful to improve the athletes' performance and to protect them from injury. The system is constructed with a skate sliding board, a couple of sensor-units with load cell, indicator and control box, guard, force pad, and support bracket. The developed force measurement system is calibrated by the calibration setup, and the uncertainty of the force sensing unit on the left is within 0.087% and the uncertainty of the force sensing unit on the right is within 0.109%. In order to check the feasibility of the developed measurement device, a kinematic analysis is conducted with skater. As a result, the subject shows the deviation of left and right of 12.1 N with respect to average strength and 39.1 N with respect to the maximum strength. This evaluation results are reliable enough to make it possible to measure a lower-body muscular strength of skaters. The use of this measurement system will be expected to correct the posture of skaters and record the sports dynamics data for each athlete. It is believed that through the development of this equipment, skaters in elementary, middle, high schools, colleges, and the professional level have the systematic training to compete with world-class skaters.

  13. Contact force control of an active pantograph for high speed trains

    NASA Astrophysics Data System (ADS)

    Ko, M. T.; Yokoyama, M.; Yamashita, Y.; Kobayashi, S.; Usuda, T.

    2016-09-01

    In this paper, a mathematical model of the pantograph with flexibility is developed based on experiments, and then an optimal controller together with a sliding observer is proposed to regulate the contact force in the presence of variation with respect to the equivalent stiffness of the catenary system. Furthermore, some physical interpretations of the closed-loop dynamics and pole-zero cancelations are given by analysis from a viewpoint of the output zeroing.

  14. Implementation of EMG- and Force-Based Control Interfaces in Active Elbow Supports for Men With Duchenne Muscular Dystrophy: A Feasibility Study.

    PubMed

    Lobo-Prat, Joan; Kooren, Peter N; Janssen, Mariska M H P; Keemink, Arvid Q L; Veltink, Peter H; Stienen, Arno H A; Koopman, Bart F J M

    2016-11-01

    While there is an extensive number of studies on the development and evaluation of electromyography (EMG)- and force-based control interfaces for assistive devices, no studies have focused on testing these control strategies for the specific case of adults with Duchenne muscular dystrophy (DMD). This paper presents a feasibility study on the use of EMG and force as control interfaces for the operation of active arm supports for men with DMD. We have built an experimental active elbow support, with a threefold objective: 1) to investigate whether adult men with DMD could use EMG- and force-based control interfaces; 2) to evaluate their performance during a discrete position-tracking task; and 3) to examine users' acceptance of the control methods. The system was tested in three adults with DMD (21-22 years). Although none of the three participants had performed any voluntary movements with their arms for the past 3-5 years, all of them were 100% successful in performing the series of tracking tasks using both control interfaces (mean task completion time EMG: [Formula: see text] , force: [Formula: see text] ). While movements with the force-based control were considerably smoother in Subject 3 and faster in Subject 1, EMG based-control was perceived as less fatiguing by all three subjects. Both EMG- and force-based interfaces are feasible solutions for the control of active elbow supports in adults with DMD and should be considered for further investigations on multi-DOF control.

  15. The QBO and weak external forcing by solar activity: A three dimensional model study

    NASA Technical Reports Server (NTRS)

    Dameris, M.; Ebel, A.

    1989-01-01

    A better understanding is attempted of the physical mechanisms leading to significant correlations between oscillations in the lower and middle stratosphere and solar variability associated with the sun's rotation. A global 3-d mechanistic model of the middle atmosphere is employed to investigate the effects of minor artificially induced perturbations. The aim is to explore the physical mechanisms of the dynamical response especially of the stratosphere to weak external forcing as it may result from UV flux changes due to solar rotation. First results of numerical experiments dealing about the external forcing of the middle atmosphere by solar activity were presented elsewhere. Different numerical studies regarding the excitation and propagation of weak perturbations have been continued since then. The model calculations presented are made to investigate the influence of the quasi-biennial oscillation (QBO) on the dynamical response of the middle atmosphere to weak perturbations by employing different initial wind fields which represent the west and east phase of the QBO.

  16. Force-Based Puncture Detection and Active Position Holding for Assisted Retinal Vein Cannulation*

    PubMed Central

    Gonenc, Berk; Tran, Nhat; Riviere, Cameron N.; Gehlbach, Peter; Taylor, Russell H.; Iordachita, Iulian

    2016-01-01

    Retinal vein cannulation is a demanding procedure proposed to treat retinal vein occlusion by direct therapeutic agent delivery methods. Challenges in identifying the moment of venous puncture, achieving cannulation and maintaining cannulation during drug delivery currently limit the feasibility of the procedure. In this study, we respond to these problems with an assistive system combining a handheld micromanipulator, Micron, with a force-sensing microneedle. The integrated system senses the instant of vein puncture based on measured forces and the position of the needle tip. The system actively holds the cannulation device securely in the vein following cannulation and during drug delivery. Preliminary testing of the system in a dry phantom, stretched vinyl membranes, demonstrates a significant improvement in the total time the needle could be maintained stably inside of the vein. This was especially evident in smaller veins and is attributed to decreased movement of the positioned cannula following venous cannulation. PMID:27127804

  17. Force-Based Puncture Detection and Active Position Holding for Assisted Retinal Vein Cannulation.

    PubMed

    Gonenc, Berk; Tran, Nhat; Riviere, Cameron N; Gehlbach, Peter; Taylor, Russell H; Iordachita, Iulian

    2015-09-01

    Retinal vein cannulation is a demanding procedure proposed to treat retinal vein occlusion by direct therapeutic agent delivery methods. Challenges in identifying the moment of venous puncture, achieving cannulation and maintaining cannulation during drug delivery currently limit the feasibility of the procedure. In this study, we respond to these problems with an assistive system combining a handheld micromanipulator, Micron, with a force-sensing microneedle. The integrated system senses the instant of vein puncture based on measured forces and the position of the needle tip. The system actively holds the cannulation device securely in the vein following cannulation and during drug delivery. Preliminary testing of the system in a dry phantom, stretched vinyl membranes, demonstrates a significant improvement in the total time the needle could be maintained stably inside of the vein. This was especially evident in smaller veins and is attributed to decreased movement of the positioned cannula following venous cannulation.

  18. Three-dimensional analysis of optical forces generated by an active tractor beam using radial polarization.

    PubMed

    Carretero, Luis; Acebal, Pablo; Blaya, Salvador

    2014-02-10

    We theoretically study the three-dimensional behavior of nanoparticles in an active optical conveyor. To do this, we solved the Langevin equation when the forces are generated by a focusing system at the near field. Analytical expressions for the optical forces generated by the optical conveyor were obtained by solving the Richards and Wolf vectorial diffraction integrals in an approximated form when a mask of two annular pupils is illuminated by a radially polarized Hermite-Gauss beam. Trajectories, in both the transverse plane and the longitudinal direction, are analyzed showing that the behavior of the optical conveyor can be optimized by conveniently choosing the configuration of the mask of the two annular pupils (inner and outer radius of the two rings) in order to trap and transport all particles at the focal plane.

  19. 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.

  20. 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

  1. Environmental Assessment, Wing Infrastructure Development Outlook (WINDO) Implementation Plan (FY 04-06). Volume 2, Beale Air Force Base, California

    DTIC Science & Technology

    2005-08-01

    Environmental Assessment Wing Infrastructure Development Outlook (WINDO) Implementation Plan (FY 04-06) Volume 2 Beale Air Force Base, California ...Development Outlook (WINDO) Implementation Plan (FY 04-06) Volume 2 Beale Air Force Base, California 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM...Beale Air Force Base (AFB). California : Volume 2. 2.0 DESCRIPTION OF PROPOSED ACTION AND NO ACTION ALTERNATIVES Proposed Action. The Proposed Action

  2. Force depression and relaxation kinetics after active shortening and deactivation in mouse soleus muscle.

    PubMed

    Van Noten, P; Van Leemputte, M

    2013-03-15

    After active shortening, isometric force production capacity of muscle is reduced (force depression, FD). The mechanism is incompletely understood but increasing cross-bridge detachment and/or decreasing attachment rate might be involved. Therefore we aimed to investigate the relation between work delivered during shortening (W), and change in half-relaxation time (Δ0.5RT) and change in the slow phase of muscle relaxation (Δkslow), considered as a marker for cross-bridge detachment rate, after shortening and after a short (0.7s) interruption of activation (deactivation). We hypothesized that shortening induces an accelerated relaxation related to W which is, similar to FD, largely abolished by a short deactivation. In 10 incubated supra-maximally stimulated mouse soleus muscles, we varied the amount of FD at L0 by varying shortening amplitude (0.6, 1.2 and 2.4mm). We found that W not only induces FD (R(2)=0.92) but also a dose dependent accelerated relaxation (R(2)=0.88 and R(2)=0.77 for respectively Δkslow and Δ0.5RT). In cyclic movements this is of functional significance, because the loss in force generating capacity might be (partially) compensated by faster relaxation. After a short deactivation, both FD and Δkslow were largely abolished but Δ0.5RT remained largely present. Under the assumption that Δkslow reflects a change in cross-bridge detachment rate, these results support the idea that FD is an intrinsic sarcomeric property originating from a work induced reduction of the number of force generating cross-bridges, however not via decreased attachment but via increased detachment rate.

  3. Localization and diffusion of tracer particles in viscoelastic media with active force dipoles

    NASA Astrophysics Data System (ADS)

    Yasuda, Kento; Okamoto, Ryuichi; Komura, Shigeyuki; Mikhailov, Alexander S.

    2017-02-01

    Optical tracking in vivo experiments reveal that diffusion of particles in biological cells is strongly enhanced in the presence of ATP and the experimental data for animal cells could previously be reproduced within a phenomenological model of a gel with myosin motors acting within it (Fodor É. et al., EPL, 110 (2015) 48005). Here, the two-fluid model of a gel is considered where active macromolecules, described as force dipoles, cyclically operate both in the elastic and the fluid components. Through coarse-graining, effective equations of motions for idealized tracer particles displaying local deformations and local fluid flows are derived. The equation for deformation tracers coincides with the earlier phenomenological model and thus confirms it. For flow tracers, diffusion enhancement caused by active force dipoles in the fluid component, and thus due to metabolic activity, is found. The latter effect may explain why ATP-dependent diffusion enhancement could also be observed in bacteria that lack molecular motors in their skeleton or when the activity of myosin motors was chemically inhibited in eukaryotic cells.

  4. Antidepressant activity of some Hypericum reflexum L. fil. extracts in the forced swimming test in mice.

    PubMed

    Sánchez-Mateo, C C; Bonkanka, C X; Prado, B; Rabanal, R M

    2007-05-30

    We previously reported that oral administration of the methanol extract obtained from the aerial part in blossom of Hypericum reflexum L. fil. was active in the tetrabenazine and forced swimming test. In the present study, the effect of the aqueous, butanol and chloroform fractions obtained from the methanol extract of this species on the central nervous system was investigated in mice, particularly in animal models of depression. Antidepressant activity was detected in the butanol and chloroform fractions of this species using the forced swimming test since both fractions induced a significant reduction of the immobility time, producing no effects or only a slight depression on spontaneous motor activity when assessed in a photocell activity meter. Moreover, these fractions did not alter significantly the pentobarbital-induced sleeping time. On the other hand, the chloroform fraction produced a slight but significant hypothermia and was also effective in antagonizing the ptosis induced by tetrabenazine. Furthermore, the butanol fraction produced a slight potentiation of the head twitches and syndrome induced by 5-HTP. Taken together, these data indicate that the butanol and chloroform fractions from Hypericum reflexum possess antidepressant-like effects in mice, providing further support for the traditional use of these plants in the Canary Islands folk medicine against central nervous disorders.

  5. Single-molecule imaging of DNA polymerase I (Klenow fragment) activity by atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Chao, J.; Zhang, P.; Wang, Q.; Wu, N.; Zhang, F.; Hu, J.; Fan, C. H.; Li, B.

    2016-03-01

    We report a DNA origami-facilitated single-molecule platform that exploits atomic force microscopy to study DNA replication. We imaged several functional activities of the Klenow fragment of E. coli DNA polymerase I (KF) including binding, moving, and dissociation from the template DNA. Upon completion of these actions, a double-stranded DNA molecule was formed. Furthermore, the direction of KF activities was captured and then confirmed by shifting the KF binding sites on the template DNA.We report a DNA origami-facilitated single-molecule platform that exploits atomic force microscopy to study DNA replication. We imaged several functional activities of the Klenow fragment of E. coli DNA polymerase I (KF) including binding, moving, and dissociation from the template DNA. Upon completion of these actions, a double-stranded DNA molecule was formed. Furthermore, the direction of KF activities was captured and then confirmed by shifting the KF binding sites on the template DNA. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06544e

  6. An Introduction to Intelligent Processing Programs Developed by the Air Force Manufacturing Technology Directorate

    NASA Technical Reports Server (NTRS)

    Sampson, Paul G.; Sny, Linda C.

    1992-01-01

    The Air Force has numerous on-going manufacturing and integration development programs (machine tools, composites, metals, assembly, and electronics) which are instrumental in improving productivity in the aerospace industry, but more importantly, have identified strategies and technologies required for the integration of advanced processing equipment. An introduction to four current Air Force Manufacturing Technology Directorate (ManTech) manufacturing areas is provided. Research is being carried out in the following areas: (1) machining initiatives for aerospace subcontractors which provide for advanced technology and innovative manufacturing strategies to increase the capabilities of small shops; (2) innovative approaches to advance machine tool products and manufacturing processes; (3) innovative approaches to advance sensors for process control in machine tools; and (4) efforts currently underway to develop, with the support of industry, the Next Generation Workstation/Machine Controller (Low-End Controller Task).

  7. Immediate loading of an implant following implant site development using forced eruption: a case report.

    PubMed

    Park, Young-Seok; Yi, Ki-Young; Moon, Seong-Cheol; Jung, Young-Chul

    2005-01-01

    In restoring periodontally involved hopeless teeth, implant treatment has been widely used with combinations of various grafting techniques or guided bone regeneration. Instead of traditional surgical procedures, forced tooth eruption may be used successfully for implant site development. In this case, the authors orthodontically erupted a hopeless central incisor with an angular bony defect. Subsequently, they placed an implant immediately after tooth extraction and immediately loaded it with a temporary resin restoration.

  8. Navy Should Join the Air Force and Army Program to Develop an Advanced Integrated Avionics System.

    DTIC Science & Technology

    1985-06-17

    to be consolidated into a single package to conserve space, save weight, and reduce costs. This report points out the potential benefits of avionics...consolidation and recommends the Navy join in a demonstration program now being conducted by the Air Force and Army to exploit such benefits . Lii LLq...the cost of a separate Navy development program. Navy officials acknowledge the benefits of ICNIA, and recognize that it will cost more for the Navy

  9. Cultural Resources Management in the United States Air Force: Development of a Planning Primer.

    DTIC Science & Technology

    1992-09-01

    1991a:11-5). The 1870’s and 1880’s saw significant efforts to preserve battlefields from the Civil War and also the Revolutionary War. The Casa Grande...directive requires each Air Force insallation to prelpe and adopt a Cultura Resources Management Plan. This plan will incude an inventoy of all cultual...geophysical components of the Legacy program. Specific to cultura resources, the task areas were developed as a general program for improving management of all

  10. A Job-Oriented Reading Program for the Air Force: Development and Field Evaluation.

    DTIC Science & Technology

    1977-05-01

    These were the modules dealing with skill practice in the job- reading tasks of using a table of contents and an index . It was felt the students coming...AD-A047 203 HUMAN RESOURCES RESEARCH ORGANIZATION ALEXANDRIA VA F/6 5/9 A JOB-ORIENTED READING PROGRAM FOR THE AIR FORCE: DEVELOPMENT A—ETC(U...Instructional Technology Branch, was the contract monitor. This report has been reviewed and cleared for open publication and/or public release by

  11. Air Force Professional Military Education and Executive Leadership and Management Development - A Summary and Annotated Bibliography

    DTIC Science & Technology

    1980-01-01

    open publication and /or public release by the appropriate Office of Information in accordance with AFR 190-17 and DODD 5230.9. There is no objection...number) Air Force 1’rofcssional Military Education (PME) is examined in a framework of thic, uxcutt[ve leadership and management development as found in...Resident programs are offered to only a percentage of the officers eligible, but alternative seminar and correspondence programs are open to everyone

  12. Air Force Dynamic Mechanical Analysis of NATO Round Robin Propellant Testing for Development of AOP-4717

    DTIC Science & Technology

    2015-09-23

    Round Robin Propellant Testing for Development of AOP-4717 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...area code) N/A Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. 239.18 0 Air Force Dynamic Mechanical Analysis of NATO Round Robin ...the clamps are tight at the coldest temperature. • Long tests such as the frequency sweep sequences prescribed in this round robin may be

  13. An Analysis of the Cost Estimating Process in Air Force Research and Development Laboratories.

    DTIC Science & Technology

    1981-09-01

    4. TITLE (and Subtitle) S. TYPE Of REPORT & PERIOO COvEREO AN ANALYSIS OF THE COST ESTIMATING PROCESS IN AIR FORCE RESEARCH AND DEVELOPMENT Master’s...final typed thesis. Her efficiency and professionalism was unexcelled. Finally, very special thanks go to my children, Chris and Brian, and especially my...42 3-6 Computer Costs - Estimating Methods. . 44 3-7 Type of Work Unit Versus Estimating Methods Used ... ............. .47 3-8 Cost Variance Between

  14. Force-field development and molecular dynamics simulations of ferrocene-peptide conjugates as a scaffold for hydrogenase mimics

    SciTech Connect

    De Hatten, Xavier; Cournia, Zoe; Smith, Jeremy C; Huc, I; Metzler-Nolte, Nils

    2007-08-01

    The increasing importance of hydrogenase enzymes in the new energy research field has led us to examine the structure and dynamics of potential hydrogenase mimics, based on a ferrocene-peptide scaffold, using molecular dynamics (MD) simulations. To enable this MD study, a molecular mechanics force field for ferrocene-bearing peptides was developed and implemented in the CHARMM simulation package, thus extending the usefulness of the package into peptide-bioorganometallic chemistry. Using the automated frequency-matching method (AFMM), optimized intramolecular force-field parameters were generated through quantum chemical reference normal modes. The partial charges for ferrocene were derived by fitting point charges to quantum-chemically computed electrostatic potentials. The force field was tested against experimental X-ray crystal structures of dipeptide derivatives of ferrocene-1,1'-dicarboxylic acid. The calculations reproduce accurately the molecular geometries, including the characteristic C{sub 2}-symmetrical intramolecular hydrogen-bonding pattern, that were stable over 0.1 {micro}s MD simulations. The crystal packing properties of ferrocene-1-(D)alanine-(D)proline-1'-(D)alanine-(D)proline were also accurately reproduced. The lattice parameters of this crystal were conserved during a 0.1 {micro}s MD simulation and match the experimental values almost exactly. Simulations of the peptides in dichloromethane are also in good agreement with experimental NMR and circular dichroism (CD) data in solution. The developed force field was used to perform MD simulations on novel, as yet unsynthesized peptide fragments that surround the active site of [Ni-Fe] hydrogenase. The results of this simulation lead us to propose an improved design for synthetic peptide-based hydrogenase models. The presented MD simulation results of metallocenes thereby provide a convincing validation of our proposal to use ferrocene-peptides as minimal enzyme mimics.

  15. Force-field development and molecular dynamics simulations of ferrocene-peptide conjugates as a scaffold for hydrogenase mimics.

    SciTech Connect

    De Hatten, Xavier; Cournia, Zoe; Smith, Jeremy C; Metzler-Nolte, Nils

    2007-08-01

    The increasing importance of hydrogenase enzymes in the new energy research field has led us to examine the structure and dynamics of potential hydrogenase mimics, based on a ferrocene-peptide scaffold, using molecular dynamics (MD) simulations. To enable this MD study, a molecular mechanics force field for ferrocene-bearing peptides was developed and implemented in the CHARMM simulation package, thus extending the usefulness of the package into peptide-bioorganometallic chemistry. Using the automated frequency-matching method (AFMM), optimized intramolecular force-field parameters were generated through quantum chemical reference normal modes. The partial charges for ferrocene were derived by fitting point charges to quantum-chemically computed electrostatic potentials. The force field was tested against experimental X-ray crystal structures of dipeptide derivatives of ferrocene-1,1{prime}-dicarboxylic acid. The calculations reproduce accurately the molecular geometries, including the characteristic C2-symmetrical intramolecular hydrogen-bonding pattern, that were stable over 0.1{micro}s MD simulations. The crystal packing properties of ferrocene-1-(D)alanine-(D)proline{prime}-1-(D)alanine-(D)proline were also accurately reproduced. The lattice parameters of this crystal were conserved during a 0.1 s MD simulation and match the experimental values almost exactly. Simulations of the peptides in dichloromethane are also in good agreement with experimental NMR and circular dichroism (CD) data in solution. The developed force field was used to perform MD simulations on novel, as yet unsynthesized peptide fragments that surround the active site of [Ni-Fe] hydrogenase. The results of this simulation lead us to propose an improved design for synthetic peptide-based hydrogenase models. The presented MD simulation results of metallocenes thereby provide a convincing validation of our proposal to use ferrocene-peptides as minimal enzyme mimics.

  16. Developing Snow Model Forcing Data From WRF Model Output to Aid in Water Resource Forecasting

    NASA Astrophysics Data System (ADS)

    Havens, S.; Marks, D. G.; Watson, K. A.; Masarik, M.; Flores, A. N.; Kormos, P.; Hedrick, A. R.

    2015-12-01

    Traditional operational modeling tools used by water managers in the west are challenged by more frequently occurring uncharacteristic stream flow patterns caused by climate change. Water managers are now turning to new models based on the physical processes within a watershed to combat the increasing number of events that do not follow the historical patterns. The USDA-ARS has provided near real time snow water equivalent (SWE) maps using iSnobal since WY2012 for the Boise River Basin in southwest Idaho and since WY2013 for the Tuolumne Basin in California that feeds the Hetch Hetchy reservoir. The goal of these projects is to not only provide current snowpack estimates but to use the Weather Research and Forecasting (WRF) model to drive iSnobal in order to produce a forecasted stream flow when coupled to a hydrology model. The first step is to develop methods on how to create snow model forcing data from WRF outputs. Using a reanalysis 1km WRF dataset from WY2009 over the Boise River Basin, WRF model results like surface air temperature, relative humidity, wind, precipitation, cloud cover, and incoming long wave radiation must be downscaled for use in iSnobal. iSnobal results forced with WRF output are validated at point locations throughout the basin, as well as compared with iSnobal results forced with traditional weather station data. The presentation will explore the differences in forcing data derived from WRF outputs and weather stations and how this affects the snowpack distribution.

  17. Development and precision position/force control of a new flexure-based microgripper

    NASA Astrophysics Data System (ADS)

    Yang, Yi-ling; Wei, Yan-ding; Lou, Jun-qiang; Xie, Feng-ran; Fu, Lei

    2016-01-01

    This paper presents the design, modeling and position/force control of a new piezo-driven microgripper with integrated position and force sensors. The structural design of the microgripper is based on double amplification mechanisms employing the bridge-type mechanism and the parallelogram mechanism. The microgripper can generate a large gripping range and pure translation of the gripping arm. Through the pseudorigid-body-model method, theoretical models are derived. By means of several finite-element analysis simulations, the optimal structural parameters for the microgripper are acquired and the theoretical models are analyzed and validated. Furthermore, to improve the performance of the microgripper, a new hybrid position/force control scheme employing a nonlinear fuzzy logic controller combined with an incremental proportional-integral controller is presented. The control scheme is capable of regulating the position and the gripping force of the microgripper simultaneously. Experimental investigation and validation were performed and the experimental results verify the effectiveness of the developed structural design and the proposed hybrid control scheme.

  18. Dissociated time course recovery between rate of force development and peak torque after eccentric exercise.

    PubMed

    Molina, Renato; Denadai, Benedito S

    2012-05-01

    This study investigated the association between isokinetic peak torque (PT) of quadriceps and the corresponding peak rate of force development (peak RFD) during the recovery of eccentric exercise. Twelve untrained men (aged 21·7 ± 2·3 year) performed 100 maximal eccentric contractions for knee extensors (10 sets of 10 repetitions with a 2-min rest between each set) on isokinetic dynamometer. PT and peak RFD accessed by maximal isokinetic knee concentric contractions at 60° s(-1) were obtained before (baseline) and at 24 and 48 h after eccentric exercise. Indirect markers of muscle damage included delayed onset of muscle soreness (DOMS) and plasma creatine kinase (CK) activity. The eccentric exercise resulted in elevated DOMS and CK compared with baseline values. At 24 h, PT (-15·3%, P = 0·002) and peak RFD (-13·1%, P = 0·03) decreased significantly. At 48 h, PT (-7·9%, P = 0·002) was still decreased but peak RFD have returned to baseline values. Positive correlation was found between PT and peak RFD at baseline (r = 0·62, P = 0·02), 24 h (r = 0·99, P = 0·0001) and 48 h (r = 0·68, P = 0·01) after eccentric exercise. The magnitude of changes (%) in PT and peak RFD from baseline to 24 h (r = 0·68, P = 0·01) and from 24 to 48 h (r = 0·68, P = 0·01) were significantly correlated. It can be concluded that the muscle damage induced by the eccentric exercise affects differently the time course of PT and peak RFD recovery during isokinetic concentric contraction at 60° s(-1). During the recovery from exercise-induced muscle damage, PT and peak RFD are determined but not fully defined by shared putative physiological mechanisms.

  19. Oxidized cholesterol as the driving force behind the development of Alzheimer’s disease

    PubMed Central

    Gamba, Paola; Testa, Gabriella; Gargiulo, Simona; Staurenghi, Erica; Poli, Giuseppe; Leonarduzzi, Gabriella

    2015-01-01

    Alzheimer’s disease (AD), the most common neurodegenerative disorder associated with dementia, is typified by the pathological accumulation of amyloid Aβ peptides and neurofibrillary tangles (NFT) within the brain. Considerable evidence indicates that many events contribute to AD progression, including oxidative stress, inflammation, and altered cholesterol metabolism. The brain’s high lipid content makes it particularly vulnerable to oxidative species, with the consequent enhancement of lipid peroxidation and cholesterol oxidation, and the subsequent formation of end products, mainly 4-hydroxynonenal and oxysterols, respectively from the two processes. The chronic inflammatory events observed in the AD brain include activation of microglia and astrocytes, together with enhancement of inflammatory molecule and free radical release. Along with glial cells, neurons themselves have been found to contribute to neuroinflammation in the AD brain, by serving as sources of inflammatory mediators. Oxidative stress is intimately associated with neuroinflammation, and a vicious circle has been found to connect oxidative stress and inflammation in AD. Alongside oxidative stress and inflammation, altered cholesterol metabolism and hypercholesterolemia also significantly contribute to neuronal damage and to progression of AD. Increasing evidence is now consolidating the hypothesis that oxidized cholesterol is the driving force behind the development of AD, and that oxysterols are the link connecting the disease to altered cholesterol metabolism in the brain and hypercholesterolemia; this is because of the ability of oxysterols, unlike cholesterol, to cross the blood brain barrier (BBB). The key role of oxysterols in AD pathogenesis has been strongly supported by research pointing to their involvement in modulating neuroinflammation, Aβ accumulation, and cell death. This review highlights the key role played by cholesterol and oxysterols in the brain in AD pathogenesis

  20. Effects of daily schedules of forced activity on free-running rhythms in the rat.

    PubMed

    Mistlberger, R E

    1991-01-01

    Circadian rhythms of hamsters can be phase-shifted or entrained by single or daily sessions of induced wheel running. In contrast, observations of rats under restricted-feeding schedules suggest that their free-running rhythms are not readily entrainable by a daily bout of intense activity. A formal test of this idea was made by subjecting rats to daily 2-hr or 3-hr sessions of forced treadmill activity. None of 18 rats entrained to a daily treadmill schedule when tested in constant dim light, but 1 of 16 did entrain when tested after blinding, when the period of its free-running activity rhythm was very close to the period of the treadmill schedule and when the onset of its daily active phase overlapped with the treadmill sessions. These conditions were recreated in a final group of eight rats; the rats were trained in a light-dark cycle, blinded, and subjected to a treadmill schedule with a period of 23.91 hr that was initiated at the onset of the rats' active phase on day 1. Six of these rats entrained. The mechanism for entrainment by activity schedules clearly exists in rats, but the conditions under which this occurs are highly constrained, suggesting that activity is a very weak zeitgeber in this species. It is argued that the evolution of functionally separable food- and light-entrainable oscillators in the rat demands a very low sensitivity to feedback effects of activity.

  1. Atomic force microscope imaging and force measurements at electrified and actively corroding interfaces: Challenges and novel cell design

    NASA Astrophysics Data System (ADS)

    Valtiner, Markus; Ankah, Genesis Ngwa; Bashir, Asif; Renner, Frank Uwe

    2011-02-01

    We report the design of an improved electrochemical cell for atomic force microscope measurements in corrosive electrochemical environments. Our design improvements are guided by experimental requirements for studying corrosive reactions such as selective dissolution, dealloying, pitting corrosion, and/or surface and interface forces at electrified interfaces. Our aim is to examine some of the limitations of typical electrochemical scanning probe microscopy (SPM) experiments and in particular to outline precautions and cell-design elements, which must necessarily be taken into account in order to obtain reliable experimental results. In particular, we discuss electrochemical requirements for typical electrochemical SPM experiments and introduce novel design features to avoid common issues such as crevice formations; we discuss the choice of electrodes and contaminations from ions of reference electrodes. We optimize the cell geometry and introduce standard samples for electrochemical AFM experiments. We have tested the novel design by performing force-distance spectroscopy as a function of the applied electrochemical potential between a bare gold electrode surface and a SAM-coated AFM tip. Topography imaging was tested by studying the well-known dealloying process of a Cu3Au(111) surface up to the critical potential. Our design improvements should be equally applicable to in situ electrochemical scanning tunneling microscope cells.

  2. Development of a mobile sensor for robust assessment of river bed grain forces

    NASA Astrophysics Data System (ADS)

    Maniatis, G.; Hoey, T.; Sventek, J.; Hodge, R. A.

    2013-12-01

    The forces experienced by sediment grains at entrainment and during transport, and those exerted on river beds, are significant for the development of river systems and landscape evolution. The assessment of local grain forces has been approached using two different methodologies. The first approach uses static impact sensors at points or cross-sections to measure velocity and/or acceleration. A second approach uses mobile natural or artificial 'smart' pebbles instrumented with inertia micro-sensors for directly measuring the local forces experienced by individual grains. The two approaches have yielded significantly different magnitudes of impact forces. Static sensors (piezoelectric plates connected to accelerometers) temporally smooth the impacts from several grains and infrequently detect the higher forces (up to ×100g) generated by direct single-grain impacts. The second method is currently unable to record the full range of impacts in real rivers due to the low measurement range of the deployed inertia sensors (×3g). Laboratory applications have required only low-range accelerometers, so excluding the magnitude of natural impacts from the design criteria. Here we present the first results from the development of a mobile sensor, designed for the purpose of measuring local grain-forces in a natural riverbed. We present two sets of measurements. The first group presents the calibration of a wide range micro-accelerometer from a set of vertical drop experiments (gravitational acceleration) and further experiments on a shaking table moving with pre-defined acceleration. The second group of measurements are from incipient motion experiments performed in a 9m x0.9m flume (slope 0.001 to 0.018) under steadily increasing discharge. Initially the spherical sensor grain was placed on an artificial surface of hemispheres of identical diameter to the sensor (111mm). Incipient motion was assessed under both whole and half-diameter exposure for each slope. Subsequently

  3. Development of a Forced Oscillation System for Measuring Dynamic Derivatives of Fluidic Vehicles

    NASA Technical Reports Server (NTRS)

    Trieu, B. C.; Tyler, T. R.; Stewart, B. K.; Chamock, J. K.; Fisher, D. W.; Heim, E. H.; Brandon, J.; Grafton, S. B.

    2006-01-01

    A new Forced Oscillation System (FOS) has been designed and built at NASA Langley Research Center that provides new capabilities for aerodynamic researchers to investigate the dynamic derivatives of vehicle configurations. Test vehicles may include high performance and general aviation aircraft, re-entry spacecraft, submarines and other fluidic vehicles. The measured data from forced oscillation testing is used in damping characteristic studies and in simulation databases for control algorithm development and performance analyses. The newly developed FOS hardware provides new flexibility for conducting dynamic derivative studies. The design is based on a tracking principle where a desired motion profile is achieved via a fast closed-loop positional controller. The motion profile for the tracking system is numerically generated and thus not limited to sinusoidal motion. This approach permits non-traditional profiles such as constant velocity and Schroeder sweeps. Also, the new system permits changes in profile parameters including nominal offset angle, waveform, and associated parameters such as amplitude and frequency. Most importantly, the changes may be made remotely without halting the FOS and the tunnel. System requirements, system analysis, and the resulting design are addressed for a new FOS in the 12-Foot Low-Speed Wind Tunnel (LSWT). The overall system including mechanical, electrical, and control subsystems is described. The design is complete, and the FOS has been built and installed in the 12-Foot LSWT. System integration and testing have verified design intent and safe operation. Currently it is being validated for wind-tunnel operations and aerodynamic testing. The system is a potential major enhancement to forced oscillation studies. The productivity gain from the motion profile automation will shorten the testing cycles needed for control surface and aircraft control algorithm development. The new motion capabilities also will serve as a test bed for

  4. Effects of replica running shoes upon external forces and muscle activity during running.

    PubMed

    Azevedo, Ana Paula Da Silva; Brandina, Kátia; Bianco, Roberto; Oliveira, Vitor Henrique De; Souza, Juliana Roque De; Mezencio, Bruno; Amadio, Alberto Carlos; Serrão, Júlio Cerca

    2012-05-01

    Twelve participants ran (9 km · h(-1)) to test two types of running shoes: replica and original shoes. Ground reaction force, plantar pressure and electromyographic activity were recorded. The shoes were tested randomly and on different days. Comparisons between the two experimental conditions were made by analysis of variance (ANOVA) test (P ≤ 0.05). The time to first peak, loading rate of the first peak and impulse of the first 75 ms of stance were significantly different between the shoes (P ≤ 0.05), revealing an increase of impact forces for the replica shoes. The peak plantar pressure values were significantly higher (P ≤ 0.05) when wearing replica shoes. During running, the contact area was significantly smaller (P ≤ 0.05) for the replica shoe. The electromyographic activity of the analysed muscles did not show changes between the two shoes in running. These findings suggest that the use of replica running shoes can increase the external load applied to the human body, but may not change the muscle activity pattern during locomotion. This new mechanical situation may increase the risk of injuries in these movements.

  5. BDNF modulates heart contraction force and long-term homeostasis through truncated TrkB.T1 receptor activation

    PubMed Central

    Fulgenzi, Gianluca; Tomassoni-Ardori, Francesco; Babini, Lucia; Becker, Jodi; Barrick, Colleen; Puverel, Sandrine

    2015-01-01

    Brain-derived neurotrophic factor (BDNF) is critical for mammalian development and plasticity of neuronal circuitries affecting memory, mood, anxiety, pain sensitivity, and energy homeostasis. Here we report a novel unexpected role of BDNF in regulating the cardiac contraction force independent of the nervous system innervation. This function is mediated by the truncated TrkB.T1 receptor expressed in cardiomyocytes. Loss of TrkB.T1 in these cells impairs calcium signaling and causes cardiomyopathy. TrkB.T1 is activated by BDNF produced by cardiomyocytes, suggesting an autocrine/paracrine loop. These findings unveil a novel signaling mechanism in the heart that is activated by BDNF and provide evidence for a global role of this neurotrophin in the homeostasis of the organism by signaling through different TrkB receptor isoforms. PMID:26347138

  6. Force-sharing between cat soleus and gastrocnemius muscles during walking: explanations based on electrical activity, properties, and kinematics.

    PubMed

    Prilutsky, B I; Herzog, W; Allinger, T L

    1994-10-01

    Studying force sharing between synergistic muscles can be useful for understanding the functional significance of musculoskeletal redundancy and the mechanisms underlying the control of synergistic muscles. The purpose of this study was to quantify and explain force sharing between cat soleus (SO) and gastrocnemius (GA) muscles, and changes in force sharing, as a function of integrated electrical activity (IEMG), contractile and mechanical properties, and kinematics of the muscles for a variety of locomotor conditions. Forces in SO and GA were measured using standard tendon force transducers of the 'buckle' type, and EMGs were recorded using bipolar, indwelling fine wire electrodes. Muscle tendon and fiber lengths, as well as the corresponding velocities, were derived from the hindlimb kinematics, anthropometric measurements, and a muscle model. In order to describe force- and IEMG-sharing between SO and GA, SO force vs GA force and SO IEMG vs GA IEMG plots were constructed. Force- and IEMG-sharing curves had a loop-like shape. Direction of formation of the loop was typically counterclockwise for forces and clockwise for IEMG; that is, forces of GA reached the maximum and then decreased faster relative to forces of SO, and IEMG of SO reached the maximum and then decreased faster relative to IEMG of GA. With increasing speeds of locomotion, the width of the force-sharing loops tended to decrease, and the width of the IEMG-sharing loops increased. Peak forces in GA muscle and peak IEMGs in SO and GA muscles tended to increase with increasing speeds of locomotion, whereas peak SO forces remained nearly constant for all activities. Because of these changes in the peak forces and IEMGs of SO and GA, the slope of the force-sharing loop decreased, and the slope of the IEMG-sharing loop did not change significantly with increasing speeds of locomotion. Length changes and velocities of SO and GA increased with the speed of locomotion and were similar in absolute magnitude

  7. Labor Force

    ERIC Educational Resources Information Center

    Occupational Outlook Quarterly, 2012

    2012-01-01

    The labor force is the number of people ages 16 or older who are either working or looking for work. It does not include active-duty military personnel or the institutionalized population, such as prison inmates. Determining the size of the labor force is a way of determining how big the economy can get. The size of the labor force depends on two…

  8. A comparison of methods for determining the rate of force development during isometric midthigh clean pulls.

    PubMed

    Haff, G Gregory; Ruben, Ryan P; Lider, Joshua; Twine, Corey; Cormie, Prue

    2015-02-01

    Twelve female division I collegiate volleyball players were recruited to examine the reliability of several methods for calculating the rate of force development (RFD) during the isometric midthigh clean pull. All subjects were familiarized with the isometric midthigh clean pull and participated in regular strength training. Two isometric midthigh clean pulls were performed with 2 minutes rest between each trail. All measures were performed in a custom isometric testing device that included a step-wise adjustable bar and a force plate for measuring ground reaction forces. The RFD during predetermined time zone bands (0-30, 0-50, 0-90, 0-100, 0-150, 0-200, and 0-250 milliseconds) was then calculated by dividing the force at the end of the band by the band's time interval. The peak RFD was then calculated with the use of 2, 5, 10, 20, 30, and 50 milliseconds sampling windows. The average RFD (avgRFD) was calculated by dividing the peak force (PF) by the time to achieve PF. All data were analyzed with the use of intraclass correlation alpha (ICCα) and the coefficient of variation (CV) and 90% confidence intervals. All predetermined RFD time bands were deemed reliable based on an ICCα >0.95 and a CV <4%. Conversely, the avgRFD failed to meet the reliability standards set for this study. Overall, the method used to assess the RFD during an isometric midthigh clean pull impacts the reliability of the measure and predetermined RFD time bands should be used to quantify the RFD.

  9. Viral hepatitis A, active component, U.S. Armed Forces, 2000-2010.

    PubMed

    2011-08-01

    From 2000 to 2010, there were 214 incident diagnoses of acute hepatitis A among active component members of the U.S. Armed Forces; the crude overall incidence rate during the period was 1.37 per 100,000 person-years. Rates of incident diagnoses of acute hepatitis A were relatively low throughout the period and much lower than during the pre-vaccine era (1990-1996). There were disproportionate numbers of diagnoses of acute hepatitis A among service members born in countries endemic for the infection. The low rates of acute hepatitis A among U.S. military members overall reflect the widespread use of hepatitis A virus vaccine.

  10. 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…

  11. Development of a Tri-Axial Cutting Force Sensor for the Milling Process

    PubMed Central

    Li, Yingxue; Zhao, Yulong; Fei, Jiyou; Zhao, You; Li, Xiuyuan; Gao, Yunxiang

    2016-01-01

    This paper presents a three-component fixed dynamometer based on a strain gauge, which reduces output errors produced by the cutting force imposed on different milling positions of the workpiece. A reformative structure of tri-layer cross beams is proposed, sensitive areas were selected, and corresponding measuring circuits were arranged to decrease the inaccuracy brought about by positional variation. To simulate the situation with a milling cutter moving on the workpiece and validate the function of reducing the output errors when the milling position changes, both static calibration and dynamic milling tests were implemented on different parts of the workpiece. Static experiment results indicate that with standard loads imposed, the maximal deviation between the measured forces and the standard inputs is 4.87%. The results of the dynamic milling test illustrate that with identical machining parameters, the differences in output variation between the developed sensor and standard dynamometer are no larger than 6.61%. Both static and dynamic experimental results demonstrate that the developed dynamometer is suitable for measuring milling force imposed on different positions of the workpiece, which shows potential applicability in machining a monitoring system. PMID:27007374

  12. Development of a Tri-Axial Cutting Force Sensor for the Milling Process.

    PubMed

    Li, Yingxue; Zhao, Yulong; Fei, Jiyou; Zhao, You; Li, Xiuyuan; Gao, Yunxiang

    2016-03-19

    This paper presents a three-component fixed dynamometer based on a strain gauge, which reduces output errors produced by the cutting force imposed on different milling positions of the workpiece. A reformative structure of tri-layer cross beams is proposed, sensitive areas were selected, and corresponding measuring circuits were arranged to decrease the inaccuracy brought about by positional variation. To simulate the situation with a milling cutter moving on the workpiece and validate the function of reducing the output errors when the milling position changes, both static calibration and dynamic milling tests were implemented on different parts of the workpiece. Static experiment results indicate that with standard loads imposed, the maximal deviation between the measured forces and the standard inputs is 4.87%. The results of the dynamic milling test illustrate that with identical machining parameters, the differences in output variation between the developed sensor and standard dynamometer are no larger than 6.61%. Both static and dynamic experimental results demonstrate that the developed dynamometer is suitable for measuring milling force imposed on different positions of the workpiece, which shows potential applicability in machining a monitoring system.

  13. Developing a standardized test procedure for hybrid vehicles: The challenge of the SAE HEV task force

    NASA Astrophysics Data System (ADS)

    Penney, Terry; Christensen, David; Poulos, Stephen

    1994-11-01

    In 1992, the Society of Automotive Engineers (SAE) established a task force to develop a procedure for measuring electric energy consumption, all-electric range, fuel economy, and exhaust emissions for hybrid vehicles; the procedure will be submitted to regulatory agencies as representing the automotive industry's recommendations. The draft procedure is currently being tested on hybrid vehicles. The University of Maryland's parallel hybrid was tested in September 1994, and the University of California-Davis' parallel hybrid and the University of Illinois' series hybrid will be tested in November 1994 and January 1995, respectively. The procedure is being modified to incorporate any lessons learned, and the task force hopes to recommend the final procedure to the SAE by mid 1995.

  14. RACORO Continental Boundary Layer Cloud Investigations: 1. Case Study Development and Ensemble Large-Scale Forcings

    NASA Technical Reports Server (NTRS)

    Vogelmann, Andrew M.; Fridlind, Ann M.; Toto, Tami; Endo, Satoshi; Lin, Wuyin; Wang, Jian; Feng, Sha; Zhang, Yunyan; Turner, David D.; Liu, Yangang; Li, Zhijin; Xie, Shaocheng; Ackerman, Andrew S.; Zhang, Minghua; Khairoutdinov, Marat

    2015-01-01

    Observation-based modeling case studies of continental boundary layer clouds have been developed to study cloudy boundary layers, aerosol influences upon them, and their representation in cloud- and global-scale models. Three 60 h case study periods span the temporal evolution of cumulus, stratiform, and drizzling boundary layer cloud systems, representing mixed and transitional states rather than idealized or canonical cases. Based on in situ measurements from the Routine AAF (Atmospheric Radiation Measurement (ARM) Aerial Facility) CLOWD (Clouds with Low Optical Water Depth) Optical Radiative Observations (RACORO) field campaign and remote sensing observations, the cases are designed with a modular configuration to simplify use in large-eddy simulations (LES) and single-column models. Aircraft measurements of aerosol number size distribution are fit to lognormal functions for concise representation in models. Values of the aerosol hygroscopicity parameter, kappa, are derived from observations to be approximately 0.10, which are lower than the 0.3 typical over continents and suggestive of a large aerosol organic fraction. Ensemble large-scale forcing data sets are derived from the ARM variational analysis, European Centre for Medium-Range Weather Forecasts, and a multiscale data assimilation system. The forcings are assessed through comparison of measured bulk atmospheric and cloud properties to those computed in "trial" large-eddy simulations, where more efficient run times are enabled through modest reductions in grid resolution and domain size compared to the full-sized LES grid. Simulations capture many of the general features observed, but the state-of-the-art forcings were limited at representing details of cloud onset, and tight gradients and high-resolution transients of importance. Methods for improving the initial conditions and forcings are discussed. The cases developed are available to the general modeling community for studying continental boundary

  15. Development of a Machine-Vision System for Recording of Force Calibration Data

    NASA Astrophysics Data System (ADS)

    Heamawatanachai, Sumet; Chaemthet, Kittipong; Changpan, Tawat

    This paper presents the development of a new system for recording of force calibration data using machine vision technology. Real time camera and computer system were used to capture images of the reading from the instruments during calibration. Then, the measurement images were transformed and translated to numerical data using optical character recognition (OCR) technique. These numerical data along with raw images were automatically saved to memories as the calibration database files. With this new system, the human error of recording would be eliminated. The verification experiments were done by using this system for recording the measurement results from an amplifier (DMP 40) with load cell (HBM-Z30-10kN). The NIMT's 100-kN deadweight force standard machine (DWM-100kN) was used to generate test forces. The experiments setup were done in 3 categories; 1) dynamics condition (record during load changing), 2) statics condition (record during fix load), and 3) full calibration experiments in accordance with ISO 376:2011. The captured images from dynamics condition experiment gave >94% without overlapping of number. The results from statics condition experiment were >98% images without overlapping. All measurement images without overlapping were translated to number by the developed program with 100% accuracy. The full calibration experiments also gave 100% accurate results. Moreover, in case of incorrect translation of any result, it is also possible to trace back to the raw calibration image to check and correct it. Therefore, this machine-vision-based system and program should be appropriate for recording of force calibration data.

  16. Development of Finite Elements for Two-Dimensional Structural Analysis Using the Integrated Force Method

    NASA Technical Reports Server (NTRS)

    Kaljevic, Igor; Patnaik, Surya N.; Hopkins, Dale A.

    1996-01-01

    The Integrated Force Method has been developed in recent years for the analysis of structural mechanics problems. This method treats all independent internal forces as unknown variables that can be calculated by simultaneously imposing equations of equilibrium and compatibility conditions. In this paper a finite element library for analyzing two-dimensional problems by the Integrated Force Method is presented. Triangular- and quadrilateral-shaped elements capable of modeling arbitrary domain configurations are presented. The element equilibrium and flexibility matrices are derived by discretizing the expressions for potential and complementary energies, respectively. The displacement and stress fields within the finite elements are independently approximated. The displacement field is interpolated as it is in the standard displacement method, and the stress field is approximated by using complete polynomials of the correct order. A procedure that uses the definitions of stress components in terms of an Airy stress function is developed to derive the stress interpolation polynomials. Such derived stress fields identically satisfy the equations of equilibrium. Moreover, the resulting element matrices are insensitive to the orientation of local coordinate systems. A method is devised to calculate the number of rigid body modes, and the present elements are shown to be free of spurious zero-energy modes. A number of example problems are solved by using the present library, and the results are compared with corresponding analytical solutions and with results from the standard displacement finite element method. The Integrated Force Method not only gives results that agree well with analytical and displacement method results but also outperforms the displacement method in stress calculations.

  17. Whole-body isometric force/torque measurements for functional assessment in neuro-rehabilitation: platform design, development and verification

    PubMed Central

    Mazzoleni, Stefano; Toth, Andras; Munih, Marko; Van Vaerenbergh, Jo; Cavallo, Giuseppe; Micera, Silvestro; Dario, Paolo; Guglielmelli, Eugenio

    2009-01-01

    Background One of the main scientific and technological challenges of rehabilitation bioengineering is the development of innovative methodologies, based on the use of appropriate technological devices, for an objective assessment of patients undergoing a rehabilitation treatment. Such tools should be as fast and cheap to use as clinical scales, which are currently the daily instruments most widely used in the routine clinical practice. Methods A human-centered approach was used in the design and development of a mechanical structure equipped with eight force/torque sensors that record quantitative data during the initiation of a predefined set of Activities of Daily Living (ADL) tasks, in isometric conditions. Results Preliminary results validated the appropriateness, acceptability and functionality of the proposed platform, that has become now a tool used for clinical research in three clinical centres. Conclusion This paper presented the design and development of an innovative platform for whole-body force and torque measurements on human subjects. The platform has been designed to perform accurate quantitative measurements in isometric conditions with the specific aim to address the needs for functional assessment tests of patients undergoing a rehabilitation treatment as a consequence of a stroke. The versatility of the system also enlightens several other interesting possible areas of application for therapy in neurorehabilitation, for research in basic neuroscience, and more. PMID:19878556

  18. Separable solutions of force-free spheres and applications to solar active regions

    SciTech Connect

    Prasad, A.; Mangalam, A.; Ravindra, B. E-mail: mangalam@iiap.res.in

    2014-05-10

    We present a systematic study of the force-free field equation for simple axisymmetric configurations in spherical geometry and apply it to the solar active regions. The condition of separability of solutions in the radial and angular variables leads to two classes of solutions: linear and nonlinear force-free fields (NLFF). We have studied these linear solutions and extended the nonlinear solutions for the radial power law index to the irreducible rational form n = p/q, which is allowed for all cases of odd p and cases of q > p for even p, where the poloidal flux ψ∝1/r{sup n} and the field B∝1/r {sup n+2}. We apply these solutions to simulate photospheric vector magnetograms obtained using the spectropolarimeter on board Hinode. The effectiveness of our search strategy is first demonstrated on test inputs of dipolar, axisymmetric, and nonaxisymmetric linear force-free fields. Using the best fit, we build three-dimensional axisymmetric field configurations and calculate the energy and relative helicity with two independent methods, which are in agreement. We have analyzed five magnetograms for AR 10930 spanning a period of three days during which two X-class flares occurred and found the free energy and relative helicity of the active region before and after the flare; our analysis indicates a peak in these quantities before the flare events, which is consistent with the other results. We also analyzed single-polarity regions AR 10923 and 10933, which showed very good fits to potential fields. This method provides useful reconstruction of NLFF and input fields for other numerical techniques.

  19. Phoretic drag reduction of chemically active homogeneous spheres under force fields and shear flows

    NASA Astrophysics Data System (ADS)

    Yariv, Ehud; Kaynan, Uri

    2017-01-01

    Surrounded by a spherically symmetric solute cloud, chemically active homogeneous spheres do not undergo conventional autophoresis when suspended in an unbounded liquid domain. When exposed to external flows, solute advection deforms that cloud, resulting in a generally asymmetric distribution of diffusio-osmotic slip which, in turn, modifies particle motion. Inspired by classical forced-convection analyses [Acrivos and Taylor, Phys. Fluids 5, 387 (1962), 10.1063/1.1706630; Frankel and Acrivos, Phys. Fluids 11, 1913 (1968), 10.1063/1.1692218] we illustrate this phoretic phenomenon using two prototypic configurations, one where the particle sediments under a uniform force field and one where it is subject to a simple shear flow. In addition to the Péclet number Pe associated with the imposed flow, the governing nonlinear problem also depends upon α , the intrinsic Péclet number associated with the chemical activity of the particle. As in the forced-convection problems, the small-Péclet-number limit is nonuniform, breaking down at large distances away from the particle. Calculation of the leading-order autophoretic effects thus requires use of matched asymptotic expansions, the outer region being at distances that scale inversely with Pe and Pe1 /2 in the respective sedimentation and shear problems. In the sedimentation problem we find an effective drag reduction of fractional amount α /8 ; in the shear problem we find that the magnitude of the stresslet is decreased by a fractional amount α /4 . For a dilute particle suspension the latter result is manifested by a reduction of the effective viscosity.

  20. Human factors in remote control engineering development activities

    SciTech Connect

    Clarke, M.M.; Hamel, W.R.; Draper, J.V.

    1983-01-01

    Human factors engineering, which is an integral part of the advanced remote control development activities at the Oak Ridge National Laboratory, is described. First, work at the Remote Systems Development Facility (RSDF) has shown that operators can perform a wide variety of tasks, some of which were not specifically designed for remote systems, with a dextrous electronic force-reflecting servomanipulator and good television remote viewing capabilities. Second, the data collected during mock-up remote maintenance experiments at the RSDF have been analyzed to provide guidelines for the design of human interfaces with an integrated advanced remote maintenance system currently under development. Guidelines have been provided for task allocation between operators, remote viewing systems, and operator controls. 6 references, 5 figures, 2 tables.

  1. Aligning Economic and Workforce Development Activities in Baltimore. Research Findings.

    ERIC Educational Resources Information Center

    Hicks, Lisa; Olins, Alexandra; Prince, Heath

    Recent efforts to build economic and work force development systems in seven leading cities were reviewed to inform similar efforts undertaken in Baltimore, Maryland. Research examining efforts to establish work force development systems in the following cities were analyzed: Austin, Texas; Berkeley, California; Boston, Massachusetts; Cleveland,…

  2. Validation and Verification of Operational Land Analysis Activities at the Air Force Weather Agency

    NASA Technical Reports Server (NTRS)

    Shaw, Michael; Kumar, Sujay V.; Peters-Lidard, Christa D.; Cetola, Jeffrey

    2011-01-01

    The NASA developed Land Information System (LIS) is the Air Force Weather Agency's (AFWA) operational Land Data Assimilation System (LDAS) combining real time precipitation observations and analyses, global forecast model data, vegetation, terrain, and soil parameters with the community Noah land surface model, along with other hydrology module options, to generate profile analyses of global soil moisture, soil temperature, and other important land surface characteristics. (1) A range of satellite data products and surface observations used to generate the land analysis products (2) Global, 1/4 deg spatial resolution (3) Model analysis generated at 3 hours

  3. Poverty and development: pulling forces and the challenges for nursing in Africa.

    PubMed

    Klopper, Hester C

    2007-12-01

    In September 2000 the United Nations Millennium Declaration was adopted and endorsed by 189 countries, translating into eight Millennium Development Goals (MDGs) to be reached by 2015. At the midpoint between the MDG adoption in 2000 and the 2015 target date for achieving the goals, Sub-Saharan Africa (SSA) is not on track to achieve their MDGs. Poverty and development are pulling forces and impact on the ability to achieve the MDGs in SSA, thus the main purpose of this article is to participate in the debate concerning the global theme of poverty and development and the challenges for the nursing profession. In this article the concepts of poverty and development are explored, and the existing trends with specific reference to SSA are investigated. An evaluation of the present status of SSA in reaching the MDG's is examined and the article concludes with a discussion of the challenges for nursing in Africa.

  4. The importance of non-quasigeostrophic forcing during the development of a blocking anticyclone

    NASA Technical Reports Server (NTRS)

    Tsou, Chih-Hua; Smith, Phillip J.

    1990-01-01

    This study examines the impact of non-quasigeostrophic (NQG) processes during the development of a blocking anticyclone (January 21, 1979 over the southern tip of Greenland) and a precursor, upstream intense cyclone (January 18, 1979). Energy quantities and height tendencies determined from quasigeostrophic estimates are compared with the same quantities obtained from more general formulations. GLA FGGE Level III-b analysis on a 4 deg lat by 5 deg long grid was used to obtain energetics results. It is concluded that NQG processes strengthened the intensity of the block and a precursor explosive cyclone and that a portion of this increase resulted from enhanced baroclinic conversion of eddy potential to eddy kinetic energy and reduced barotropic energy conversion from eddy to zonal flow. It is suggested that NQG vorticity advection, instead of moderating wave developments, enhanced the block development, and it is also suggested that QG forcing might not have been adequate to produce the observed block development.

  5. High Speed Photography, Videography, And Photonic Instrumentation Development At The Air Force Armament Laboratory

    NASA Astrophysics Data System (ADS)

    Snyder, Donald R.; Powell, Rodney M.

    1989-02-01

    The Instrumentation Technology Branch of the Air Force Armament Laboratory is currently involved in the development of several high speed photographic, videographic, and photonic instrumentation systems to support the testing and analysis of developmental weapons and test items under dynamic conditions. These projects include development of a large format (14 inch by 17 inch) laser illuminated Cranz-Schardin shadowgraph system for materials research, development of a solid state imager based shadowgraph system for aeroballistic studies, experiments with gated imagers for a variety of test applications, and experiments with high speed video imagers and illuminators for airborne and range tracking instrumentation. An additional issue discussed is the development of a timing and annotation standard for video imaging instrumentation systems operating at higher than NTSC standard rates.

  6. Development of a multicomponent force and moment balance for water tunnel applications, volume 2

    NASA Technical Reports Server (NTRS)

    Suarez, Carlos J.; Malcolm, Gerald N.; Kramer, Brian R.; Smith, Brooke C.; Ayers, Bert F.

    1994-01-01

    The principal objective of this research effort was to develop a multicomponent strain gauge balance to measure forces and moments on models tested in flow visualization water tunnels. Static experiments (which are discussed in Volume 1 of this report) were conducted, and the results showed good agreement with wind tunnel data on similar configurations. Dynamic experiments, which are the main topic of this Volume, were also performed using the balance. Delta wing models and two F/A-18 models were utilized in a variety of dynamic tests. This investigation showed that, as expected, the values of the inertial tares are very small due to the low rotating rates required in a low-speed water tunnel and can, therefore, be ignored. Oscillations in pitch, yaw and roll showed hysteresis loops that compared favorably to data from dynamic wind tunnel experiments. Pitch-up and hold maneuvers revealed the long persistence, or time-lags, of some of the force components in response to the motion. Rotary-balance experiments were also successfully performed. The good results obtained in these dynamic experiments bring a whole new dimension to water tunnel testing and emphasize the importance of having the capability to perform simultaneous flow visualization and force/moment measurements during dynamic situations.

  7. Developing multisite empirical force field models for Pt(II) and cisplatin.

    PubMed

    Cvitkovic, John P; Kaminski, George A

    2017-01-30

    We have developed empirical force field parameters for Pt(II) and cisplatin. Two force field frameworks were used-modified OPLS-AA and our second-order polarizable POSSIM. A seven-site model was used for the Pt(II) ion. The goal was to create transferable parameter sets compatible with the force field models for proteins and general organic compounds. A number of properties of the Pt(II) ion and its coordination compounds have been considered, including geometries and energies of the complexes, hydration free energy, and radial distribution functions in water. Comparison has been made with experimental and quantum mechanical results. We have demonstrated that both versions are generally capable of reproducing key properties of the system, but the second-order polarizable POSSIM formalism permits more accurate quantitative results to be obtained. For example, the energy of formation of cisplatin as calculated with the modified OPLS-AA exhibited an error of 9.9%, while the POSSIM error for the same quantity was 6.2%. The produced parameter sets are transferable and suitable to be used in protein-metal binding simulations in which position or even coordination of the ion does not have to be constrained using preexisting knowledge. © 2016 Wiley Periodicals, Inc.

  8. Development of a multicomponent force and moment balance for water tunnel applications, volume 1

    NASA Technical Reports Server (NTRS)

    Suarez, Carlos J.; Malcolm, Gerald N.; Kramer, Brian R.; Smith, Brooke C.; Ayers, Bert F.

    1994-01-01

    The principal objective of this research effort was to develop a multicomponent strain gauge balance to measure forces and moments on models tested in flow visualization water tunnels. An internal balance was designed that allows measuring normal and side forces, and pitching, yawing and rolling moments (no axial force). The five-components to applied loads, low interactions between the sections and no hysteresis. Static experiments (which are discussed in this Volume) were conducted in the Eidetics water tunnel with delta wings and a model of the F/A-18. Experiments with the F/A-18 model included a thorough baseline study and investigations of the effect of control surface deflections and of several Forebody Vortex Control (FVC) techniques. Results were compared to wind tunnel data and, in general, the agreement is very satisfactory. The results of the static tests provide confidence that loads can be measured accurately in the water tunnel with a relatively simple multicomponent internal balance. Dynamic experiments were also performed using the balance, and the results are discussed in detail in Volume 2 of this report.

  9. Demonstration Model Development of the Force-Balanced Coil for SMES

    NASA Astrophysics Data System (ADS)

    Nomura, Shinichi; Kasuya, Koji; Tanaka, Norihiro; Tsuboi, Kenji; Tsutsui, Hiroaki; Shimada, Ryuichi; Ninomiya, Akira; Ishigohka, Takashi

    In large-scale SMES, the superconducting coils require special considerations for induced electromagnetic forces to limit allowable tensile stress. Force-balanced coil (FBC) is a helically wound hybrid coil of toroidal field coils and a solenoid. The FBC can significantly reduce the required mass of the structure for induced electromagnetic forces. In order to demonstrate the feasibility of the FBC concept for SMES, the authors have developed a superconducting model coil. The outer diameter of the model FBC is 0.53m. The hand-made winding, using NbTi/Cu composite strands with a diameter of 1.17mm, was finished with 10584 poloidal turns after four months. The helical windings of the model FBC were neither impregnated with epoxy resin nor reinforced with stainless steel wires. Three test runs were conducted with liquid helium cooling at intervals of several months. The number of quench tests was 81 in total. The first quench current was 293A, which was 53% of the critical coil current. The training phenomena could be observed even after the coil was warmed up to room temperature. After successive quenches the quench current was improved to 476A, corresponding to 86% of the critical coil current, and it was successfully excited up to 6.1T.

  10. Development of a multicomponent force and moment balance for water tunnel applications, volume 1

    NASA Astrophysics Data System (ADS)

    Suarez, Carlos J.; Malcolm, Gerald N.; Kramer, Brian R.; Smith, Brooke C.; Ayers, Bert F.

    1994-12-01

    The principal objective of this research effort was to develop a multicomponent strain gauge balance to measure forces and moments on models tested in flow visualization water tunnels. An internal balance was designed that allows measuring normal and side forces, and pitching, yawing and rolling moments (no axial force). The five-components to applied loads, low interactions between the sections and no hysteresis. Static experiments (which are discussed in this Volume) were conducted in the Eidetics water tunnel with delta wings and a model of the F/A-18. Experiments with the F/A-18 model included a thorough baseline study and investigations of the effect of control surface deflections and of several Forebody Vortex Control (FVC) techniques. Results were compared to wind tunnel data and, in general, the agreement is very satisfactory. The results of the static tests provide confidence that loads can be measured accurately in the water tunnel with a relatively simple multicomponent internal balance. Dynamic experiments were also performed using the balance, and the results are discussed in detail in Volume 2 of this report.

  11. Development of a multicomponent force and moment balance for water tunnel applications, volume 2

    NASA Astrophysics Data System (ADS)

    Suarez, Carlos J.; Malcolm, Gerald N.; Kramer, Brian R.; Smith, Brooke C.; Ayers, Bert F.

    1994-12-01

    The principal objective of this research effort was to develop a multicomponent strain gauge balance to measure forces and moments on models tested in flow visualization water tunnels. Static experiments (which are discussed in Volume 1 of this report) were conducted, and the results showed good agreement with wind tunnel data on similar configurations. Dynamic experiments, which are the main topic of this Volume, were also performed using the balance. Delta wing models and two F/A-18 models were utilized in a variety of dynamic tests. This investigation showed that, as expected, the values of the inertial tares are very small due to the low rotating rates required in a low-speed water tunnel and can, therefore, be ignored. Oscillations in pitch, yaw and roll showed hysteresis loops that compared favorably to data from dynamic wind tunnel experiments. Pitch-up and hold maneuvers revealed the long persistence, or time-lags, of some of the force components in response to the motion. Rotary-balance experiments were also successfully performed. The good results obtained in these dynamic experiments bring a whole new dimension to water tunnel testing and emphasize the importance of having the capability to perform simultaneous flow visualization and force/moment measurements during dynamic situations.

  12. Development of optical FBG force measurement system for the medical application

    NASA Astrophysics Data System (ADS)

    Song, Hoseok; Kim, Kiyoung; Suh, Jungwook; Lee, Jungju

    2009-12-01

    Haptic feedback plays a very important role in medical surgery. In minimally invasive surgery (MIS), however, very long and stiff bar of instruments take haptic feeling away from the surgeon. In minimally invasive robotic surgery (MIRS), moreover, haptic feelings are totally eliminated. Previous researchers have reported that the absence of force feedback increased the average force magnitude applied to the tissue by at least 50%, and increased the peakforce magnitude by at least a factor of two. Therefore, it is very important to provide haptic information in MIRS. Recently, many sensors are being developed for MIS or MIRS, but they have some obstacles in their application to real situations of medical surgery. The most critical problems are size limit and sterilizability. Optical fiber sensors are one of the most suitable sensors for this environment. Especially, optical fiber Bragg grating (FBG) sensor has one additional advantage than the other optical fiber sensors. FBG sensor is not influenced by intensity of light source. In this paper, we would like to present the initial results of study on the application of the FBG sensor to measure reflected forces in MIRS environments and then suggest the possibility of successful application to the MIRS systems.

  13. Development of optical FBG force measurement system for the medical application

    NASA Astrophysics Data System (ADS)

    Song, Hoseok; Kim, Kiyoung; Suh, Jungwook; Lee, Jungju

    2010-03-01

    Haptic feedback plays a very important role in medical surgery. In minimally invasive surgery (MIS), however, very long and stiff bar of instruments take haptic feeling away from the surgeon. In minimally invasive robotic surgery (MIRS), moreover, haptic feelings are totally eliminated. Previous researchers have reported that the absence of force feedback increased the average force magnitude applied to the tissue by at least 50%, and increased the peakforce magnitude by at least a factor of two. Therefore, it is very important to provide haptic information in MIRS. Recently, many sensors are being developed for MIS or MIRS, but they have some obstacles in their application to real situations of medical surgery. The most critical problems are size limit and sterilizability. Optical fiber sensors are one of the most suitable sensors for this environment. Especially, optical fiber Bragg grating (FBG) sensor has one additional advantage than the other optical fiber sensors. FBG sensor is not influenced by intensity of light source. In this paper, we would like to present the initial results of study on the application of the FBG sensor to measure reflected forces in MIRS environments and then suggest the possibility of successful application to the MIRS systems.

  14. Observed differences in upper extremity forces, muscle efforts, postures, velocities and accelerations across computer activities in a field study of office workers.

    PubMed

    Bruno Garza, J L; Eijckelhof, B H W; Johnson, P W; Raina, S M; Rynell, P W; Huysmans, M A; van Dieën, J H; van der Beek, A J; Blatter, B M; Dennerlein, J T

    2012-01-01

    This study, a part of the PRedicting Occupational biomechanics in OFfice workers (PROOF) study, investigated whether there are differences in field-measured forces, muscle efforts, postures, velocities and accelerations across computer activities. These parameters were measured continuously for 120 office workers performing their own work for two hours each. There were differences in nearly all forces, muscle efforts, postures, velocities and accelerations across keyboard, mouse and idle activities. Keyboard activities showed a 50% increase in the median right trapezius muscle effort when compared to mouse activities. Median shoulder rotation changed from 25 degrees internal rotation during keyboard use to 15 degrees external rotation during mouse use. Only keyboard use was associated with median ulnar deviations greater than 5 degrees. Idle activities led to the greatest variability observed in all muscle efforts and postures measured. In future studies, measurements of computer activities could be used to provide information on the physical exposures experienced during computer use. Practitioner Summary: Computer users may develop musculoskeletal disorders due to their force, muscle effort, posture and wrist velocity and acceleration exposures during computer use. We report that many physical exposures are different across computer activities. This information may be used to estimate physical exposures based on patterns of computer activities over time.

  15. A forced damped oscillation framework for undulatory swimming provides new insights into how propulsion arises in active and passive swimming.

    PubMed

    Bhalla, Amneet Pal Singh; Griffith, Boyce E; Patankar, Neelesh A

    2013-01-01

    A fundamental issue in locomotion is to understand how muscle forcing produces apparently complex deformation kinematics leading to movement of animals like undulatory swimmers. The question of whether complicated muscle forcing is required to create the observed deformation kinematics is central to the understanding of how animals control movement. In this work, a forced damped oscillation framework is applied to a chain-link model for undulatory swimming to understand how forcing leads to deformation and movement. A unified understanding of swimming, caused by muscle contractions ("active" swimming) or by forces imparted by the surrounding fluid ("passive" swimming), is obtained. We show that the forcing triggers the first few deformation modes of the body, which in turn cause the translational motion. We show that relatively simple forcing patterns can trigger seemingly complex deformation kinematics that lead to movement. For given muscle activation, the forcing frequency relative to the natural frequency of the damped oscillator is important for the emergent deformation characteristics of the body. The proposed approach also leads to a qualitative understanding of optimal deformation kinematics for fast swimming. These results, based on a chain-link model of swimming, are confirmed by fully resolved computational fluid dynamics (CFD) simulations. Prior results from the literature on the optimal value of stiffness for maximum speed are explained.

  16. Development of a two-step, forced chemical vapor infiltration process

    SciTech Connect

    Matlin, W.M.; Stinton, D.P.; Besmann, T.M.

    1995-12-01

    A two-step forced chemical vapor infiltration process was developed that reduced infiltration times for 4.45 cm dia. by 1.27 cm thick Nicalon{trademark} fiber pre-forms by two thirds while maintaining final densities near 90%. In the first stage of the process, micro-voids within fiber bundles in the cloth were uniformly infiltrated throughout the preform. In the second stage, the deposition rate was increased to more rapidly fill the macro-voids between bundles within the cloth and between layers of cloth. By varying the thermal gradient across the preform uniform infiltration rates were maintained and high final densities achieved.

  17. Note: Design and development of an integrated three-dimensional scanner for atomic force microscopy

    SciTech Connect

    Rashmi, T.; Dharsana, G.; Sriramshankar, R.; Sri Muthu Mrinalini, R.; Jayanth, G. R.

    2013-11-15

    A compact scanning head for the Atomic Force Microscope (AFM) greatly enhances the portability of AFM and facilitates easy integration with other tools. This paper reports the design and development of a three-dimensional (3D) scanner integrated into an AFM micro-probe. The scanner is realized by means of a novel design for the AFM probe along with a magnetic actuation system. The integrated scanner, the actuation system, and their associated mechanical mounts are fabricated and evaluated. The experimentally calibrated actuation ranges are shown to be over 1 μm along all the three axes.

  18. Note: Design and development of an integrated three-dimensional scanner for atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Rashmi, T.; Dharsana, G.; Sriramshankar, R.; Sri Muthu Mrinalini, R.; Jayanth, G. R.

    2013-11-01

    A compact scanning head for the Atomic Force Microscope (AFM) greatly enhances the portability of AFM and facilitates easy integration with other tools. This paper reports the design and development of a three-dimensional (3D) scanner integrated into an AFM micro-probe. The scanner is realized by means of a novel design for the AFM probe along with a magnetic actuation system. The integrated scanner, the actuation system, and their associated mechanical mounts are fabricated and evaluated. The experimentally calibrated actuation ranges are shown to be over 1 μm along all the three axes.

  19. Calibration of an interfacial force microscope for MEMS metrology : FY08-09 activities.

    SciTech Connect

    Houston, Jack E.; Baker, Michael Sean; Crowson, Douglas A.; Mitchell, John Anthony; Moore, Nathan W.

    2009-10-01

    Progress in MEMS fabrication has enabled a wide variety of force and displacement sensing devices to be constructed. One device under intense development at Sandia is a passive shock switch, described elsewhere (Mitchell 2008). A goal of all MEMS devices, including the shock switch, is to achieve a high degree of reliability. This, in turn, requires systematic methods for validating device performance during each iteration of design. Once a design is finalized, suitable tools are needed to provide quality assurance for manufactured devices. To ensure device performance, measurements on these devices must be traceable to NIST standards. In addition, accurate metrology of MEMS components is needed to validate mechanical models that are used to design devices to accelerate development and meet emerging needs. Progress towards a NIST-traceable calibration method is described for a next-generation, 2D Interfacial Force Microscope (IFM) for applications in MEMS metrology and qualification. Discussed are the results of screening several suitable calibration methods and the known sources of uncertainty in each method.

  20. The ReaxFF reactive force-field: development, applications and future directions

    NASA Astrophysics Data System (ADS)

    Senftle, Thomas P.; Hong, Sungwook; Islam, Md Mahbubul; Kylasa, Sudhir B.; Zheng, Yuanxia; Shin, Yun Kyung; Junkermeier, Chad; Engel-Herbert, Roman; Janik, Michael J.; Aktulga, Hasan Metin; Verstraelen, Toon; Grama, Ananth; van Duin, Adri C. T.

    2016-03-01

    The reactive force-field (ReaxFF) interatomic potential is a powerful computational tool for exploring, developing and optimizing material properties. Methods based on the principles of quantum mechanics (QM), while offering valuable theoretical guidance at the electronic level, are often too computationally intense for simulations that consider the full dynamic evolution of a system. Alternatively, empirical interatomic potentials that are based on classical principles require significantly fewer computational resources, which enables simulations to better describe dynamic processes over longer timeframes and on larger scales. Such methods, however, typically require a predefined connectivity between atoms, precluding simulations that involve reactive events. The ReaxFF method was developed to help bridge this gap. Approaching the gap from the classical side, ReaxFF casts the empirical interatomic potential within a bond-order formalism, thus implicitly describing chemical bonding without expensive QM calculations. This article provides an overview of the development, application, and future directions of the ReaxFF method.

  1. Development of a ReaxFF Reactive Force Field for the Pt-Ni Alloy Catalyst.

    PubMed

    Shin, Yun Kyung; Gai, Lili; Raman, Sumathy; van Duin, Adri C T

    2016-10-03

    We developed the ReaxFF force field for Pt/Ni/C/H/O interactions, specifically targeted for heterogeneous catalysis application of the Pt-Ni alloy. The force field is trained using the DFT data for equations of state of Pt3Ni, PtNi3 and PtNi alloys, the surface energy of the PtxNi1-x(111) (x = 0.67-0.83), and binding energies of various atomic and molecular species (O, H, C, CH, CH2, CH3, CO, OH, and H2O) on these surfaces. The ReaxFF force field shows a Pt surface segregation at x ≥ 0.67 for the (111) surface and x ≥ 0.62 for the (100) surface in vacuum. In addition, from the investigation of the preferential alloy component of the adsorbates, it is expected that H and CH3 on the alloy surface to induce a segregation of Pt whereas the oxidation intermediates and products such as C, O, OH, H2O, CO, CH, and CH2 are found to induce Ni segregation. The relative order of binding strengths among adsorbates is a function of alloy composition and the force field is trained to describe the trend observed in DFT calculations, namely, H2 < H2O < CH3 ≈ O2 ≈ CO < OH < CH2 < C ≈ CH on Pt8Ni4, H2 < H2O < CO < O2 ≈ CH3 < OH < CH2 < CH < C on Pt9Ni3, and H2 < H2O < O2 < CO < CH3 < OH < CH2 < C ≈ CH on Pt10Ni2. Using this force field, we performed the grand-canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations for a Pt3Ni slab and a truncated cuboctahedral nanoparticle terminated by (111) and (100) faces, to examine the surface segregation trend under different gas environments. It is found that Pt segregates to the alloy surface when the surface is exposed to vacuum and/or H2 environment while Ni segregates under the O2 environment. These results suggest that the Pt/Ni alloy force field can be successfully used for the preparation of Pt-Ni nanobimetallic catalysts structure using GCMC and run MD simulations to investigate its role and the catalytic chemistry in catalytic oxidation, dehydrogenation and coupling reactions. The current Pt/Ni force field

  2. 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.

  3. Active disturbance rejection control for output force creep characteristics of ionic polymer metal composites

    NASA Astrophysics Data System (ADS)

    Xiong, Yan; Chen, Yang; Sun, Zhiyong; Hao, Lina; Dong, Jie

    2014-07-01

    Ionic polymer metal composites (IPMCs) are a type of electroactive polymer (EAP) that can be used as both sensors and actuators. An IPMC has enormous potential application in the field of biomimetic robotics, medical devices, and so on. However, an IPMC actuator has a great number of disadvantages, such as creep and time-variation, making it vulnerable to external disturbances. In addition, the complex actuation mechanism makes it difficult to model and the demand of the control algorithm is laborious to implement. In this paper, we obtain a creep model of the IPMC by means of model identification based on the method of creep operator linear superposition. Although the mathematical model is not approximate to the IPMC accurate model, it is accurate enough to be used in MATLAB to prove the control algorithm. A controller based on the active disturbance rejection control (ADRC) method is designed to solve the drawbacks previously given. Because the ADRC controller is separate from the mathematical model of the controlled plant, the control algorithm has the ability to complete disturbance estimation and compensation. Some factors, such as all external disturbances, uncertainty factors, the inaccuracy of the identification model and different kinds of IPMCs, have little effect on controlling the output block force of the IPMC. Furthermore, we use the particle swarm optimization algorithm to adjust ADRC parameters so that the IPMC actuator can approach the desired block force with unknown external disturbances. Simulations and experimental examples validate the effectiveness of the ADRC controller.

  4. Active-Region Twist Derived from Magnetic Tongues and Linear Force-Free Extrapolations

    NASA Astrophysics Data System (ADS)

    Poisson, Mariano; López Fuentes, Marcelo; Mandrini, Cristina H.; Démoulin, Pascal

    2015-11-01

    The main aim of this study is to compare the amount of twist present in emerging active regions (ARs) from photospheric and coronal data. We use linear force-free field models of the observed coronal structure of ARs to determine the global twist. The coronal twist is derived, on one hand, from the force-free parameter [α] of the model and, on the other, from the computed coronal magnetic helicity normalized by the magnetic flux squared. We compare our results, for the same set of ARs, with those of Poisson et al. ( Solar Phys. 290, 727, 2015), in which the twist was estimated using the so-called magnetic tongues observed in line-of-sight magnetograms during AR emergence. We corroborate the agreement between the photospheric and coronal twist-sign and the presence of magnetic tongues as an early proxy of the AR non-potentiality. We find a globally linear relationship between the coronal twist and the one previously deduced for the emerging AR flux rope at the photospheric level. The coronal-twist value is typically lower by a factor of six than the one deduced for the emerging flux rope. We interpret this result as due to the partial emergence of the flux rope that forms the region.

  5. 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.…

  6. 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…

  7. 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…

  8. 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.

  9. 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)…

  10. 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…

  11. Synchronous fire activity in the tropical high Andes: an indication of regional climate forcing.

    PubMed

    Román-Cuesta, R M; Carmona-Moreno, C; Lizcano, G; New, M; Silman, M; Knoke, T; Malhi, Y; Oliveras, I; Asbjornsen, H; Vuille, M

    2014-06-01

    Global climate models suggest enhanced warming of the tropical mid and upper troposphere, with larger temperature rise rates at higher elevations. Changes in fire activity are amongst the most significant ecological consequences of rising temperatures and changing hydrological properties in mountainous ecosystems, and there is a global evidence of increased fire activity with elevation. Whilst fire research has become popular in the tropical lowlands, much less is known of the tropical high Andean region (>2000 masl, from Colombia to Bolivia). This study examines fire trends in the high Andes for three ecosystems, the Puna, the Paramo and the Yungas, for the period 1982-2006. We pose three questions: (i) is there an increased fire response with elevation? (ii) does the El Niño- Southern Oscillation control fire activity in this region? (iii) are the observed fire trends human driven (e.g., human practices and their effects on fuel build-up) or climate driven? We did not find evidence of increased fire activity with elevation but, instead, a quasicyclic and synchronous fire response in Ecuador, Peru and Bolivia, suggesting the influence of high-frequency climate forcing on fire responses on a subcontinental scale, in the high Andes. ENSO variability did not show a significant relation to fire activity for these three countries, partly because ENSO variability did not significantly relate to precipitation extremes, although it strongly did to temperature extremes. Whilst ENSO did not individually lead the observed regional fire trends, our results suggest a climate influence on fire activity, mainly through a sawtooth pattern of precipitation (increased rainfall before fire-peak seasons (t-1) followed by drought spells and unusual low temperatures (t0), which is particularly common where fire is carried by low fuel loads (e.g., grasslands and fine fuel). This climatic sawtooth appeared as the main driver of fire trends, above local human influences and fuel build

  12. Functional Brain Activity Relates to 0-3 and 3-8 Hz Force Oscillations in Essential Tremor.

    PubMed

    Neely, Kristina A; Kurani, Ajay S; Shukla, Priyank; Planetta, Peggy J; Wagle Shukla, Aparna; Goldman, Jennifer G; Corcos, Daniel M; Okun, Michael S; Vaillancourt, David E

    2015-11-01

    It is well-established that during goal-directed motor tasks, patients with essential tremor have increased oscillations in the 0-3 and 3-8 Hz bands. It remains unclear if these increased oscillations relate to activity in specific brain regions. This study used task-based functional magnetic resonance imaging to compare the brain activity associated with oscillations in grip force output between patients with essential tremor, patients with Parkinson's disease who had clinically evident tremor, and healthy controls. The findings demonstrate that patients with essential tremor have increased brain activity in the motor cortex and supplementary motor area compared with controls, and this activity correlated positively with 3-8 Hz force oscillations. Brain activity in cerebellar lobules I-V was reduced in essential tremor compared with controls and correlated negatively with 0-3 Hz force oscillations. Widespread differences in brain activity were observed between essential tremor and Parkinson's disease. Using functional connectivity analyses during the task evidenced reduced cerebellar-cortical functional connectivity in patients with essential tremor compared with controls and Parkinson's disease. This study provides new evidence that in essential tremor 3-8 Hz force oscillations relate to hyperactivity in motor cortex, 0-3 Hz force oscillations relate to the hypoactivity in the cerebellum, and cerebellar-cortical functional connectivity is impaired.

  13. Astronomy for a Better World: IAU OAD Task Force-1 Programs for Advancing Astronomy Education and Research in Universities in Developing Countries

    NASA Astrophysics Data System (ADS)

    Guinan, Edward; Kolenberg, Katrien

    2015-03-01

    We discuss the IAU Commission 46 and Office for Astronomy Development (OAD) programs that support advancing Astronomy education and research primarily in universities in developing countries. The bulk of these operational activities will be coordinated through the OAD's newly installed Task Force 1. We outline current (and future) IAU/OAD Task Force-1 programs that promote the development of University-level Astronomy at both undergraduate and graduate levels. Among current programs discussed are the past and future expanded activities of the International School for Young Astronomers (ISYA) and the Teaching Astronomy for Development (TAD) programs. The primary role of the ISYA program is the organization of a three week School for students for typically M.Sc. and Ph.D students. The ISYA is a very successful program that will now be offered more frequently through the generous support of the Kavli Foundation. The IAU/TAD program provides aid and resources for the development of teaching, education and research in Astronomy. The TAD program is dedicated to assist countries that have little or no astronomical activity, but that wish to develop or enhance Astronomy education. Over the last ten years, the ISYA and TAD programs have supported programs in Africa, Asia, Central America and the Caribbean, the Middle East, South East and West Asia, and South America. Several examples are given. Several new programs being considered by OAD Task Force-1 are also discussed. Other possible programs being considered are the introduction of modular Astronomy courses into the university curricula (or improve present courses) as well as providing access to ``remote learning`` courses and Virtual Astronomy labs in developing countries. Another possible new program would support visits of astronomers from technically advanced countries to spend their sabbatical leaves teaching and advising University Astronomy programs in developing countries. Suggestions for new Task Force -1

  14. Development of High Performance CFRP/Metal Active Laminates

    NASA Astrophysics Data System (ADS)

    Asanuma, Hiroshi; Haga, Osamu; Imori, Masataka

    This paper describes development of high performance CFRP/metal active laminates mainly by investigating the kind and thickness of the metal. Various types of the laminates were made by hot-pressing of an aluminum, aluminum alloys, a stainless steel and a titanium for the metal layer as a high CTE material, a unidirectional CFRP prepreg as a low CTE/electric resistance heating material, a unidirectional KFRP prepreg as a low CTE/insulating material. The aluminum and its alloy type laminates have almost the same and the highest room temperature curvatures and they linearly change with increasing temperature up to their fabrication temperature. The curvature of the stainless steel type jumps from one to another around its fabrication temperature, whereas the titanium type causes a double curvature and its change becomes complicated. The output force of the stainless steel type attains the highest of the three under the same thickness. The aluminum type successfully increased its output force by increasing its thickness and using its alloys. The electric resistance of the CFRP layer can be used to monitor the temperature, that is, the curvature of the active laminate because the curvature is a function of temperature.

  15. Development of glycyl radical parameters for the OPLS-AA/L force field.

    PubMed

    Komáromi, István; Owen, Michael C; Murphy, Richard F; Lovas, Sándor

    2008-09-01

    On the basis of quantum chemical calculations C(alpha)-glycyl radical parameters have been developed for the OPLS-AA/L force field. The molecular mechanics hypersurface was fitted to the calculated quantum chemical surface by minimizing their molecular mechanics parameter dependent sum-of-squares deviations. To do this, a computer program in which the molecular mechanics energy derivatives with respect to the parameters were calculated analytically was developed, implementing the general method of Lifson and Warshel (J Chem Phys 1968, 49, 5116) for force field parameter optimization. This program, in principle, can determine the optimal parameter set in one calculation if enough representative value points on the quantum chemical potential energy surface are available and there is no linear dependency between the parameters. Some of the parameters in quantum calculations, including several new torsion types around a bond as well as angle parameters at a new central atom type, are not completely separable. Consequently, some restrictions and/or presumptions were necessary during parameter optimization. The relative OPLS-AA energies reproduced those calculated quantum chemically almost perfectly.

  16. Development of an Empirical Force Field for Silica. Application to the Quartz-Water Interface

    PubMed Central

    Lopes, Pedro E. M.; Murashov, Vladimir; Tazi, Mouhsine; Demchuk, Eugene; MacKerell, Alexander D.

    2008-01-01

    Interactions of pulverized crystalline silica with biological systems, including the lungs, cause cell damage, inflammation, and apoptosis. To allow computational atomistic modeling of these pathogenic processes, including interactions between silica surfaces and biological molecules, new parameters for quartz, compatible with the CHARMM empirical force field were developed. Parameters were optimized to reproduce the experimental geometry of α-quartz, ab initio vibrational spectra and interactions between model compounds and water. The newly developed force field was used to study interactions of water with two singular surfaces of α-quartz, (011) and (100). Properties monitored and analyzed include the variation of the density of water molecules in the plane perpendicular to the surface, disruption of the water H-bond network upon adsorption, and space-time correlations of water oxygen atoms in terms of Van Hove self correlation functions. The Vibrational Density of States (VDOS) spectra of water in confined compartments were also computed and compared with experimental neutron-scattering results. Both the attenuation and shifting to higher frequencies of the hindered translational peaks upon confinement are clearly reproduced by the model. However, an upshift of librational peaks under the conditions of model confinement still remains underrepresented at the current empirical level. PMID:16471886

  17. Development and Optimization of Dynamic Atomic Force Microscopy Techniques with Applications in Soft Matter Characterization

    NASA Astrophysics Data System (ADS)

    Eslami, Babak

    The overall goals of this project are (i) to improve the current dynamic modes of atomic force microscopy (AFM) with the focus of multifrequency AFM measurements on soft matters in ambient air and liquid environments and (ii) to develop a new methodology for mechanically characterizing the subsurface of soft samples, allowing users to gradually, controllably and reversibly reveal features that are buried under the surface. This dissertation includes a wide range of studies on multifrequency atomic force microscopy. Firstly, the imaging parameters (drive amplitude and frequency) of each eigenmode is studied, optimized based on the observables. Secondly, a new mutltifrequency AFM technique with capability of imaging subsurface features has been developed and verified through experiments. Based on the first goal of the project, an experimental protocol to select excitation frequency in air for single tapping mode and bimodal AFM are provided. Additionally, a rigorous guideline for the selection of drive frequency in ambient air, liquid environment based on the energy quantities and slope of the cantilever's phase response is established. Finally, an advantage of using higher and stiffer eigenmodes for imaging soft matters has been proposed and verified experimentally. By this technique, subsurface imaging capabilities of AFM are expanded.

  18. Active diffusion and microtubule-based transport oppose myosin forces to position organelles in cells

    NASA Astrophysics Data System (ADS)

    Lin, Congping; Schuster, Martin; Guimaraes, Sofia Cunha; Ashwin, Peter; Schrader, Michael; Metz, Jeremy; Hacker, Christian; Gurr, Sarah Jane; Steinberg, Gero

    2016-06-01

    Even distribution of peroxisomes (POs) and lipid droplets (LDs) is critical to their role in lipid and reactive oxygen species homeostasis. How even distribution is achieved remains elusive, but diffusive motion and directed motility may play a role. Here we show that in the fungus Ustilago maydis ~95% of POs and LDs undergo diffusive motions. These movements require ATP and involve bidirectional early endosome motility, indicating that microtubule-associated membrane trafficking enhances diffusion of organelles. When early endosome transport is abolished, POs and LDs drift slowly towards the growing cell end. This pole-ward drift is facilitated by anterograde delivery of secretory cargo to the cell tip by myosin-5. Modelling reveals that microtubule-based directed transport and active diffusion support distribution, mobility and mixing of POs. In mammalian COS-7 cells, microtubules and F-actin also counteract each other to distribute POs. This highlights the importance of opposing cytoskeletal forces in organelle positioning in eukaryotes.

  19. An intelligent active force control algorithm to control an upper extremity exoskeleton for motor recovery

    NASA Astrophysics Data System (ADS)

    Hasbullah Mohd Isa, Wan; Taha, Zahari; Mohd Khairuddin, Ismail; Majeed, Anwar P. P. Abdul; Fikri Muhammad, Khairul; Abdo Hashem, Mohammed; Mahmud, Jamaluddin; Mohamed, Zulkifli

    2016-02-01

    This paper presents the modelling and control of a two degree of freedom upper extremity exoskeleton by means of an intelligent active force control (AFC) mechanism. The Newton-Euler formulation was used in deriving the dynamic modelling of both the anthropometry based human upper extremity as well as the exoskeleton that consists of the upper arm and the forearm. A proportional-derivative (PD) architecture is employed in this study to investigate its efficacy performing joint-space control objectives. An intelligent AFC algorithm is also incorporated into the PD to investigate the effectiveness of this hybrid system in compensating disturbances. The Mamdani Fuzzy based rule is employed to approximate the estimated inertial properties of the system to ensure the AFC loop responds efficiently. It is found that the IAFC-PD performed well against the disturbances introduced into the system as compared to the conventional PD control architecture in performing the desired trajectory tracking.

  20. Incidence of gastroesophageal reflux disease (GERD), active component, U.S. Armed Forces, 2005-2014.

    PubMed

    Daniele, Denise O; Oh, Gi-Taik; O'Donnell, Francis L; Clark, Leslie L

    2015-07-01

    Gastroesophageal reflux disease (GERD) is a common condition among adults that can cause symptoms such as frequent heartburn, substernal chest pain, and regurgitation of food. During 2005-2014, a total of 137,081 active component service members had an incident (first-ever) diagnosis of GERD (incidence rate: 101.3 per 10,000 person-years). Incidence rates were higher than their respective counterparts among females, black and white non-Hispanics, service members in the Coast Guard and Air Force, officers, and those in healthcare occupations. Rates increased monotonically with increasing age groups. Most GERD cases (79.2%) were uncomplicated GERD; however, 20.8% were identified as having a symptom or complication linked to their GERD diagnosis. Lifestyle changes, medication, and prevention of serious complications should be emphasized among individuals diagnosed with GERD, particularly those at risk for severe disease.

  1. Active diffusion and microtubule-based transport oppose myosin forces to position organelles in cells

    PubMed Central

    Lin, Congping; Schuster, Martin; Guimaraes, Sofia Cunha; Ashwin, Peter; Schrader, Michael; Metz, Jeremy; Hacker, Christian; Gurr, Sarah Jane; Steinberg, Gero

    2016-01-01

    Even distribution of peroxisomes (POs) and lipid droplets (LDs) is critical to their role in lipid and reactive oxygen species homeostasis. How even distribution is achieved remains elusive, but diffusive motion and directed motility may play a role. Here we show that in the fungus Ustilago maydis ∼95% of POs and LDs undergo diffusive motions. These movements require ATP and involve bidirectional early endosome motility, indicating that microtubule-associated membrane trafficking enhances diffusion of organelles. When early endosome transport is abolished, POs and LDs drift slowly towards the growing cell end. This pole-ward drift is facilitated by anterograde delivery of secretory cargo to the cell tip by myosin-5. Modelling reveals that microtubule-based directed transport and active diffusion support distribution, mobility and mixing of POs. In mammalian COS-7 cells, microtubules and F-actin also counteract each other to distribute POs. This highlights the importance of opposing cytoskeletal forces in organelle positioning in eukaryotes. PMID:27251117

  2. Active control of structurally-coupled sound fields in elastic cylinders by vibrational force inputs

    NASA Technical Reports Server (NTRS)

    Jones, J. D.; Fuller, C. R.

    1990-01-01

    Active control of structurally-coupled sound fields in elastic cylinders is analytically and experimentally studied. The primary (noise) field in the cylinder model is generated by the coupled dynamic response of the shell under loading by a single exterior acoustic source. Control of the interior sound field is achieved by applying vibrational force inputs directly to the shell wall. Action of the point controllers serve to increase the input impedance of select structural modes of the shell which are well-coupled to the interior acoustic cavity, thus substantially reducing sound transmission into the cavity. Spatially-averaged noise reductions in excess of 30 dB are demonstrated for acoustic resonant conditions within the cavity. Twin controller configurations are presented which demonstrate the ability to independently control orthogonal modes of the interior acoustic space. Benefits and drawbacks of this new methodology for noise control are discussed and clearly demonstrated.

  3. Bubble mass center and fluid feedback force fluctuations activated by constant lateral impulse with variable thrust

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Long, Y. T.

    1995-01-01

    Sloshing dynamics within a partially filled rotating dewar of superfluid helium 2 are investigated in response to constant lateral impulse with variable thrust. The study, including how the rotating bubble of superfluid helium 2 reacts to the constant impulse with variable time period of thrust action in microgravity, how amplitudes of bubble mass center fluctuates with growth and decay of disturbances, and how fluid feedback forces fluctuates in activating on the rotating dewar through the dynamics of sloshing waves are investigated. The numerical computation of sloshing dynamics is based on the non-inertial frame spacecraft bound coordinate with lateral impulses actuating on the rotating dewar in both inertial and non-inertial frames of thrust. Results of the simulations are illustrated.

  4. From Forced Tolerance to Forced Busing: Wartime Intercultural Education and the Rise of Black Educational Activism in Boston

    ERIC Educational Resources Information Center

    Burkholder, Zoe

    2010-01-01

    In this article, Zoe Burkholder explores the historical interplay of the emergence of tolerance education in the United States and the rise of black educational activism in Boston. By uncovering a pointed lack of tolerance education in Boston and a widespread promotion of tolerance education in other cities in the early half of the twentieth…

  5. One-dimensional potential of mean force underestimates activation barrier for transport across flexible lipid membranes

    NASA Astrophysics Data System (ADS)

    Kopelevich, Dmitry I.

    2013-10-01

    Transport of a fullerene-like nanoparticle across a lipid bilayer is investigated by coarse-grained molecular dynamics (MD) simulations. Potentials of mean force (PMF) acting on the nanoparticle in a flexible bilayer suspended in water and a bilayer restrained to a flat surface are computed by constrained MD simulations. The rate of the nanoparticle transport into the bilayer interior is predicted using one-dimensional Langevin models based on these PMFs. The predictions are compared with the transport rates obtained from a series of direct (unconstrained) MD simulations of the solute transport into the flexible bilayer. It is observed that the PMF acting on the solute in the flexible membrane underestimates the transport rate by more than an order of magnitude while the PMF acting on the solute in the restrained membrane yields an accurate estimate of the activation energy for transport into the flexible membrane. This paradox is explained by a coexistence of metastable membrane configurations for a range of the solute positions inside and near the flexible membrane. This leads to a significant reduction of the contribution of the transition state to the mean force acting on the solute. Restraining the membrane shape ensures that there is only one stable membrane configuration corresponding to each solute position and thus the transition state is adequately represented in the PMF. This mechanism is quite general and thus this phenomenon is expected to occur in a wide range of interfacial systems. A simple model for the free energy landscape of the coupled solute-membrane system is proposed and validated. This model explicitly accounts for effects of the membrane deformations on the solute transport and yields an accurate prediction of the activation energy for the solute transport.

  6. One-dimensional potential of mean force underestimates activation barrier for transport across flexible lipid membranes.

    PubMed

    Kopelevich, Dmitry I

    2013-10-07

    Transport of a fullerene-like nanoparticle across a lipid bilayer is investigated by coarse-grained molecular dynamics (MD) simulations. Potentials of mean force (PMF) acting on the nanoparticle in a flexible bilayer suspended in water and a bilayer restrained to a flat surface are computed by constrained MD simulations. The rate of the nanoparticle transport into the bilayer interior is predicted using one-dimensional Langevin models based on these PMFs. The predictions are compared with the transport rates obtained from a series of direct (unconstrained) MD simulations of the solute transport into the flexible bilayer. It is observed that the PMF acting on the solute in the flexible membrane underestimates the transport rate by more than an order of magnitude while the PMF acting on the solute in the restrained membrane yields an accurate estimate of the activation energy for transport into the flexible membrane. This paradox is explained by a coexistence of metastable membrane configurations for a range of the solute positions inside and near the flexible membrane. This leads to a significant reduction of the contribution of the transition state to the mean force acting on the solute. Restraining the membrane shape ensures that there is only one stable membrane configuration corresponding to each solute position and thus the transition state is adequately represented in the PMF. This mechanism is quite general and thus this phenomenon is expected to occur in a wide range of interfacial systems. A simple model for the free energy landscape of the coupled solute-membrane system is proposed and validated. This model explicitly accounts for effects of the membrane deformations on the solute transport and yields an accurate prediction of the activation energy for the solute transport.

  7. The development of a two-component force dynamometer and tool control system for dynamic machine tool research

    NASA Technical Reports Server (NTRS)

    Sutherland, I. A.

    1973-01-01

    The development is presented of a tooling system that makes a controlled sinusoidal oscillation simulating a dynamic chip removal condition. It also measures the machining forces in two mutually perpendicular directions without any cross sensitivity.

  8. Activity in the premotor area related to bite force control--a functional near-infrared spectroscopy study.

    PubMed

    Takeda, Tomotaka; Shibusawa, Mami; Sudal, Osamu; Nakajima, Kazunori; Ishigami, Keiichi; Sakatani, Kaoru

    2010-01-01

    The purpose of this study was to elucidate the influence of bite force control on oxygenated hemoglobin (OxyHb) levels in regional cerebral blood flow as an indicator of brain activity in the premotor area. Healthy right-handed volunteers with no subjective or objective symptoms of problems of the stomatognathic system or cervicofacial region were included. Functional near-infrared spectroscopy (fNIRS) was used to determine OxyHb levels in the premotor area during bite force control. A bite block equipped with an occlusal force sensor was prepared to measure clenching at the position where the right upper and lower canine cusps come into contact. Intensity of clenching was shown on a display and feedback was provided to the subjects. Intensity was set at 20, 50 and 80% of maximum voluntary teeth clenching force. To minimize the effect of the temporal muscle on the working side of the jaw, the fNIRS probes were positioned contralaterally, in the left region. The findings of this study are: activation of the premotor area with bite force control was noted in all subjects, and in the group analysis OxyHb in the premotor cortex was significantly increased as the clenching strengthened at 20, 50 and 80% of maximum voluntary clenching force. These results suggest there is a possibility that the premotor area is involved in bite force control.

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

    PubMed Central

    Kang, Jong Ho; Park, Tae-Sung

    2015-01-01

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

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

    PubMed

    Kang, Jong Ho; Park, Tae-Sung

    2015-09-01

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

  11. Force and twist dependence of RepC nicking activity on torsionally-constrained DNA molecules

    PubMed Central

    Pastrana, Cesar L.; Carrasco, Carolina; Akhtar, Parvez; Leuba, Sanford H.; Khan, Saleem A.; Moreno-Herrero, Fernando

    2016-01-01

    Many bacterial plasmids replicate by an asymmetric rolling-circle mechanism that requires sequence-specific recognition for initiation, nicking of one of the template DNA strands and unwinding of the duplex prior to subsequent leading strand DNA synthesis. Nicking is performed by a replication-initiation protein (Rep) that directly binds to the plasmid double-stranded origin and remains covalently bound to its substrate 5′-end via a phosphotyrosine linkage. It has been proposed that the inverted DNA sequences at the nick site form a cruciform structure that facilitates DNA cleavage. However, the role of Rep proteins in the formation of this cruciform and the implication for its nicking and religation functions is unclear. Here, we have used magnetic tweezers to directly measure the DNA nicking and religation activities of RepC, the replication initiator protein of plasmid pT181, in plasmid sized and torsionally-constrained linear DNA molecules. Nicking by RepC occurred only in negatively supercoiled DNA and was force- and twist-dependent. Comparison with a type IB topoisomerase in similar experiments highlighted a relatively inefficient religation activity of RepC. Based on the structural modeling of RepC and on our experimental evidence, we propose a model where RepC nicking activity is passive and dependent upon the supercoiling degree of the DNA substrate. PMID:27488190

  12. Update: Exertional hyponatremia, active component, U.S. Armed Forces, 1999-2013.

    PubMed

    2014-03-01

    From 1999 through 2013, there were 1,406 incident diagnoses of exertional hyponatremia among active component members of the U.S. Armed Forces. Annual incidence rates rose sharply from 2008 to 2010 but decreased by 59 percent from 2010 to 2013. In 2013, there were fewer incident cases (n=73) than in any of the previous 9 years. The recent decrease in overall rates reflects sharply declining rates in the Marine Corps and slight decreases in the other Services. Relative to their respective counterparts, crude incidence rates of exertional hyponatremia for the entire 15-year surveillance period were higher among females, those in the youngest age group, Marines, recruit trainees, and "other" military occupations. Service members (particularly recruit trainees) and their supervisors must be vigilant for early signs of heat-related illnesses and must be knowledgeable of the dangers of excessive water consumption and the prescribed limits for water intake during prolonged physical activity (e.g., field training exercises, personal fitness training, recreational activities) in hot, humid weather.

  13. Development of residential-conservation-survey methodology for the US Air Force. Interim report. Task two

    SciTech Connect

    Abrams, D. W.; Hartman, T. L.; Lau, A. S.

    1981-11-13

    A US Air Force (USAF) Residential Energy Conservation Methodology was developed to compare USAF needs and available data to the procedures of the Residential Conservation Service (RCS) program as developed for general use by utility companies serving civilian customers. Attention was given to the data implications related to group housing, climatic data requirements, life-cycle cost analysis, energy saving modifications beyond those covered by RCS, and methods for utilizing existing energy consumption data in approaching the USAF survey program. Detailed information and summaries are given on the five subtasks of the program. Energy conservation alternatives are listed and the basic analysis techniques to be used in evaluating their thermal performane are described. (MCW)

  14. Development of low noise cantilever deflection sensor for multienvironment frequency-modulation atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Fukuma, Takeshi; Kimura, Masayuki; Kobayashi, Kei; Matsushige, Kazumi; Yamada, Hirofumi

    2005-05-01

    We have developed a low noise cantilever deflection sensor with a deflection noise density of 17fm/√Hz by optimizing the parameters used in optical beam deflection (OBD) method. Using this sensor, we have developed a multienvironment frequency-modulation atomic force microscope (FM-AFM) that can achieve true molecular resolution in various environments such as in moderate vacuum, air, and liquid. The low noise characteristic of the deflection sensor makes it possible to obtain a maximum frequency sensitivity limited by the thermal Brownian motion of the cantilever in every environment. In this paper, the major noise sources in OBD method are discussed in both theoretical and experimental aspects. The excellent noise performance of the deflection sensor is demonstrated in deflection and frequency measurements. True molecular-resolution FM-AFM images of a polydiacetylene single crystal taken in vacuum, air, and water are presented.

  15. Development of low noise cantilever deflection sensor for multienvironment frequency-modulation atomic force microscopy

    SciTech Connect

    Fukuma, Takeshi; Kimura, Masayuki; Kobayashi, Kei; Matsushige, Kazumi; Yamada, Hirofumi

    2005-05-15

    We have developed a low noise cantilever deflection sensor with a deflection noise density of 17 fm/{radical}(Hz) by optimizing the parameters used in optical beam deflection (OBD) method. Using this sensor, we have developed a multienvironment frequency-modulation atomic force microscope (FM-AFM) that can achieve true molecular resolution in various environments such as in moderate vacuum, air, and liquid. The low noise characteristic of the deflection sensor makes it possible to obtain a maximum frequency sensitivity limited by the thermal Brownian motion of the cantilever in every environment. In this paper, the major noise sources in OBD method are discussed in both theoretical and experimental aspects. The excellent noise performance of the deflection sensor is demonstrated in deflection and frequency measurements. True molecular-resolution FM-AFM images of a polydiacetylene single crystal taken in vacuum, air, and water are presented.

  16. Disaster relief activities of the Japan self-defense force following the Great East Japan Earthquake.

    PubMed

    Nishiyama, Yasumasa

    2014-06-01

    Cooperation between civilian and military forces, including the Japan Self-Defense Force (JSDF), enabled wide-ranging disaster relief after the Great East Japan Earthquake. Nevertheless, many preventable fatalities occurred, particularly related to an inability to treat chronic disease, indicating the need to plan for the provision of long-term medical aid after natural disasters in stricken areas and evacuation shelters. To assist in this effort, this report (1) provides an overview of the consequences of the medical response to the Great East Japan Earthquake, the largest natural disaster ever to hit Japan, focusing on the role and actions of the JSDF; (2) discusses the lessons learned regarding the provision of medical aid and management by the JSDF after this disaster, looking at the special challenges of meeting the needs of a rapidly aging population in a disaster situation; and (3) provides recommendations for the development of strategies for the long-term medical aid and support after natural disasters, especially with regard to the demographics of the Japanese population.

  17. A comparison of assessment methods of hand activity and force for use in calculating the ACGIH(R) hand activity level (HAL) TLV(R).

    PubMed

    Wurzelbacher, Steve; Burt, Susan; Crombie, Ken; Ramsey, Jessica; Luo, Lian; Allee, Steve; Jin, Yan

    2010-07-01

    This article compares several methods that were used for determining hand activity level and force in a large prospective ergonomics study. The first goal of this analysis was to determine the degree of correlation between hand activity/ force ratings using different assessment methods. The second goal was to determine if the hand activity/force methods were functionally equivalent for the purpose of calculating the ACGIH(R) hand activity level (HAL) threshold limit value (TLV(R)). A final goal was to investigate reasons for potential differences between methods. More than 700 task analyses were conducted on 484 workers at three study locations. Hand activity was assessed by two methods, including a trained observer on site using a 10-point visual analog scale for hand activity level and by offsite video analysis of the same task to calculate the frequency of exertions and the work/recovery ratio. Hand force was assessed by two on-site methods: ratings of perceived exertion (RPE) using a modified Borg CR-10 scale by a trained observer and RPE by the worker performing the task. The two methods for assessing hand activity level were correlated (Spearman rank = 0.49) and produced main TLV result categories (below Action Limit, Action Limit, TLV) with percent of exact agreement ranging from 71 to 91% and weighted Kappa ranging from 0.61 to 0.75. The two RPE methods for assessing hand force were correlated (Spearman rank ranging from 0.47 to 0.69) and produced TLVs with percent of exact agreement ranging from 64 to 83% and weighted Kappa ranging from 0.52 to 0.62. Differences between methods may be explained by a number of task and subject variables that were significantly associated with higher levels of hand activity and force. In summary, this study found substantial agreement between two methods for assessing hand activity level and moderate agreement between two methods for assessing hand force.

  18. Professional Development: A Six-Year Data Evaluation of HIDTA Law Enforcement Task Force Training Programs

    ERIC Educational Resources Information Center

    Burnett, Larry D.

    2012-01-01

    This is a nationwide six-year data study of law enforcement training and professional development in relationship to workplace productivity. Why do we care about law enforcement training and professional development? Because the law enforcement environment is not standing still. Unlawful activity, and in particular drug trafficking strategies,…

  19. Preparing the periphery for a subsequent behavior: motor neuronal activity during biting generates little force but prepares a retractor muscle to generate larger forces during swallowing in Aplysia.

    PubMed

    Lu, Hui; McManus, Jeffrey M; Cullins, Miranda J; Chiel, Hillel J

    2015-03-25

    Some behaviors occur in obligatory sequence, such as reaching before grasping an object. Can the earlier behavior serve to prepare the musculature for the later behavior? If it does, what is the underlying neural mechanism of the preparation? To address this question, we examined two feeding behaviors in the marine mollusk Aplysia californica, one of which must precede the second: biting and swallowing. Biting is an attempt to grasp food. When that attempt is successful, the animal immediately switches to swallowing to ingest food. The main muscle responsible for pulling food into the buccal cavity during swallowing is the I3 muscle, whose motor neurons B6, B9, and B3 have been previously identified. By performing recordings from these neurons in vivo in intact, behaving animals or in vitro in a suspended buccal mass preparation, we demonstrated that the frequencies and durations of these motor neurons increased from biting to swallowing. Using the physiological patterns of activation to drive these neurons intracellularly, we further demonstrated that activating them using biting-like frequencies and durations, either alone or in combination, generated little or no force in the I3 muscle. When biting-like patterns preceded swallowing-like patterns, however, the forces during the subsequent swallowing-like patterns were significantly enhanced. Sequences of swallowing-like patterns, either with these neurons alone or in combination, further enhanced forces in the I3 muscle. These results suggest a novel mechanism for enhancing force production in a muscle, and may be relevant to understanding motor control in vertebrates.

  20. North Atlantic Tropical Cyclone Activity over the last 2000 years: Patterns, Consequences and Potential Climatic Forcing

    NASA Astrophysics Data System (ADS)

    Donnelly, J. P.; Lane, P.; Hawkes, A.; van Hengstum, P. J.; Ranasinghe, P. N.; Toomey, M.; MacDonald, D.

    2011-12-01

    1300 years ago. A reconstruction of intense hurricane landfalls from the Gulf coast documents some similar patterns that likely point to large scale climate forcing; however, some significant differences are evident. For example, the Gulf frequently experienced intense hurricanes during the 13th and 14th centuries, but a subsequent decline in activity has persisted through the historic period. This antiphasing of intense hurricane activity between the East and Gulf coasts may point to basin-wide changes in hurricane tracks, but regional controls on the frequency of intense hurricanes (e.g., loop current penetration in the Gulf of Mexico) may also have driven spatial variability in Atlantic paleohurricane records.

  1. 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.

  2. Quadriceps Rate of Force Development affects Gait and Function in People with Knee Osteoarthritis

    PubMed Central

    Winters, Joshua D.; Rudolph, Katherine S.

    2014-01-01

    Objective Quadriceps weakness exists in people with knee osteoarthritis (OA) but other muscle factors like rate of force development (RFD) may also be affected by knee OA. The purpose of this study was to determine if people with knee OA have deficits in quadriceps RFD, determine if quadriceps RFD would improve predicting knee joint power absorption and generation during free and fast walking, and determine if RFD would improve predicting functional outcomes. Methods 26 subjects with knee OA and 23 healthy control subjects performed maximal voluntary isometric strength (MVIC) and RFD measures of the quadriceps. Subjects also underwent a 3-D motion analysis of both self-selected free and self-selected fast walking speeds. Joint kinetics were calculated from inverse dynamics. Results RFD was not different by group (p=0.763), however the OA subjects generated the highest peak RFD at a lower %MVIC (p=0.008). Controls walked significantly faster at both free and fast walking speeds (p=0.001, p=0.029). Knee angles at heel strike and peak knee extension were lower (p=0.004, p=0.027) in the OA group. During fast walking knee power generation was higher in Controls (p=0.028). MVIC and force of highest peak RFD predicted KOOS ADL score in the OA subjects, but only MVIC predicted stair climbing time. Conclusions The submaximal force at which peak RFD occurs plays a significant role in knee joint power as well as functional measures in the OA subjects, providing further evidence that factors other than maximal strength are also important in people with knee OA. PMID:24240535

  3. Changes in force associated with the amount of aligner activation and lingual bodily movement of the maxillary central incisor

    PubMed Central

    Li, Xiaowei; Ren, Chaochao; Wang, Zheyao; Zhao, Pai; Wang, Hongmei

    2016-01-01

    Objective The purposes of this study were to measure the orthodontic forces generated by thermoplastic aligners and investigate the possible influences of different activations for lingual bodily movements on orthodontic forces, and their attenuation. Methods Thermoplastic material of 1.0-mm in thickness was used to manufacture aligners for 0.2, 0.3, 0.4, 0.5, and 0.6 mm activations for lingual bodily movements of the maxillary central incisor. The orthodontic force in the lingual direction delivered by the thermoplastic aligners was measured using a micro-stress sensor system for the invisible orthodontic technique, and was monitored for 2 weeks. Results Orthodontic force increased with the amount of activation of the aligner in the initial measurements. The attenuation speed in the 0.6 mm group was faster than that of the other groups (p < 0.05). All aligners demonstrated rapid relaxation in the first 8 hours, which then decreased slowly and plateaued on day 4 or 5. Conclusions The amount of activation had a substantial influence on the orthodontic force imparted by the aligners. The results suggest that the activation of lingual bodily movement of the maxillary central incisor should not exceed 0.5 mm. The initial 4 or 5 days is important with respect to orthodontic treatment incorporating an aligner. PMID:27019820

  4. Sea ice thermodynamics and high latitudes freshwater forcing developments in a global operational oceanographic context.

    NASA Astrophysics Data System (ADS)

    Bricaud, Clement; Garric, Gilles; Bourdalle-badie, Romain; Chanut, Jerome

    2015-04-01

    Mercator Ocean, the French operational oceanography center (www.mercator-ocean.fr), developed several real time forecasting and reanalysis systems of the 3D-Ocean. In the framework of the Myocean EU (FP7 and Horizon 2020, www.myocean.eu.org) funded projects, Mercator is principally in charge of the development of real time analysis and forecasts for the global ocean at the 1/12° horizontal resolution. It has also already produced global eddy-permitting (1/4°) reanalysis over the altimetry years (1992-2013) With a large freshening of the upper Arctic Ocean, the thinning of the Arctic sea ice cover and the large melting ice caps, high latitudes are presently facing substantial changes. The needs of improving the sea ice representation and the fresh water forcing and assessing the dynamical and thermo-haline equilibrium of the water masses are growing in terms of hindcasts, nowcasts and forecasts in these rapid changing areas. Two main developments have been implemented and tested in the NEMO-based model component of the global 1/4 ° reanalysis system: - A new version of Louvain-La-Neuve sea ice model, e.g. LIM3, available in the last NEMO3.6 release has been tested in an interannual experiment driven by the 1979-2013 ERA-Interim atmospheric at the surface. Compared to the previous version LIM2 which includes the basic mono-category and 3-layer thermodynamics, LIM3 is a multi category and multi layers sea ice model together with an explicit sea ice salinity evolution. Compared to available data sets, the LIM3 model gives a better representation of the Arctic sea ice thickness distribution. Representation of the sea ice thermodynamics and of the upper layers water masses at high latitudes are discussed and compared to a similar LIM2 experiment. - Based on Altiberg icebergs project dataset (Tournadre et al., 2012, [1]),Gravity Recovery and Climate Experiment (GRACE)-based ocean mass signal and the IPCC's Fifth assessment Report (AR5) estimations, an interannual

  5. Talin1 is critical for force-dependent reinforcement of initial integrin–cytoskeleton bonds but not tyrosine kinase activation

    PubMed Central

    Giannone, Grégory; Jiang, Guoying; Sutton, Deborah H.; Critchley, David R.; Sheetz, Michael P.

    2003-01-01

    Cells rapidly transduce forces exerted on extracellular matrix contacts into tyrosine kinase activation and recruitment of cytoskeletal proteins to reinforce integrin–cytoskeleton connections and initiate adhesion site formation. The relationship between these two processes has not been defined, particularly at the submicrometer level. Using talin1-deficient cells, it appears that talin1 is critical for building early mechanical linkages. Deletion of talin1 blocked laser tweezers, force-dependent reinforcement of submicrometer fibronectin-coated beads and early formation of adhesion sites in response to force, even though Src family kinases, focal adhesion kinase, and spreading were activated normally. Recruitment of vinculin and paxillin to sites of force application also required talin1. FilaminA had a secondary role in strengthening fibronectin–integrin–cytoskeleton connections and no role in stretch-dependent adhesion site assembly. Thus, force-dependent activation of tyrosine kinases is independent of early force-dependent structural changes that require talin1 as part of a critical scaffold. PMID:14581461

  6. Talin1 is critical for force-dependent reinforcement of initial integrin-cytoskeleton bonds but not tyrosine kinase activation.

    PubMed

    Giannone, Grégory; Jiang, Guoying; Sutton, Deborah H; Critchley, David R; Sheetz, Michael P

    2003-10-27

    Cells rapidly transduce forces exerted on extracellular matrix contacts into tyrosine kinase activation and recruitment of cytoskeletal proteins to reinforce integrin-cytoskeleton connections and initiate adhesion site formation. The relationship between these two processes has not been defined, particularly at the submicrometer level. Using talin1-deficient cells, it appears that talin1 is critical for building early mechanical linkages. Deletion of talin1 blocked laser tweezers, force-dependent reinforcement of submicrometer fibronectin-coated beads and early formation of adhesion sites in response to force, even though Src family kinases, focal adhesion kinase, and spreading were activated normally. Recruitment of vinculin and paxillin to sites of force application also required talin1. FilaminA had a secondary role in strengthening fibronectin-integrin-cytoskeleton connections and no role in stretch-dependent adhesion site assembly. Thus, force-dependent activation of tyrosine kinases is independent of early force-dependent structural changes that require talin1 as part of a critical scaffold.

  7. 26 CFR 31.3401(a)(1)-1 - Remuneration of members of the Armed Forces of the United States for active service in combat...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 15 2014-04-01 2014-04-01 false Remuneration of members of the Armed Forces of... members of the Armed Forces of the United States for active service in combat zone or while hospitalized as a result of such service. Remuneration paid for active service as a member of the Armed Forces...

  8. 26 CFR 31.3401(a)(1)-1 - Remuneration of members of the Armed Forces of the United States for active service in combat...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 15 2010-04-01 2010-04-01 false Remuneration of members of the Armed Forces of... members of the Armed Forces of the United States for active service in combat zone or while hospitalized as a result of such service. Remuneration paid for active service as a member of the Armed Forces...

  9. 26 CFR 31.3401(a)(1)-1 - Remuneration of members of the Armed Forces of the United States for active service in combat...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 15 2013-04-01 2013-04-01 false Remuneration of members of the Armed Forces of... members of the Armed Forces of the United States for active service in combat zone or while hospitalized as a result of such service. Remuneration paid for active service as a member of the Armed Forces...

  10. 26 CFR 31.3401(a)(1)-1 - Remuneration of members of the Armed Forces of the United States for active service in combat...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 15 2011-04-01 2011-04-01 false Remuneration of members of the Armed Forces of... members of the Armed Forces of the United States for active service in combat zone or while hospitalized as a result of such service. Remuneration paid for active service as a member of the Armed Forces...

  11. 26 CFR 31.3401(a)(1)-1 - Remuneration of members of the Armed Forces of the United States for active service in combat...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 15 2012-04-01 2012-04-01 false Remuneration of members of the Armed Forces of... members of the Armed Forces of the United States for active service in combat zone or while hospitalized as a result of such service. Remuneration paid for active service as a member of the Armed Forces...

  12. Biomechanical forces promote blood development through prostaglandin E2 and the cAMP-PKA signaling axis.

    PubMed

    Diaz, Miguel F; Li, Nan; Lee, Hyun Jung; Adamo, Luigi; Evans, Siobahn M; Willey, Hannah E; Arora, Natasha; Torisawa, Yu-Suke; Vickers, Dwayne A; Morris, Samantha A; Naveiras, Olaia; Murthy, Shashi K; Ingber, Donald E; Daley, George Q; García-Cardeña, Guillermo; Wenzel, Pamela L

    2015-05-04

    Blood flow promotes emergence of definitive hematopoietic stem cells (HSCs) in the developing embryo, yet the signals generated by hemodynamic forces that influence hematopoietic potential remain poorly defined. Here we show that fluid shear stress endows long-term multilineage engraftment potential upon early hematopoietic tissues at embryonic day 9.5, an embryonic stage not previously described to harbor HSCs. Effects on hematopoiesis are mediated in part by a cascade downstream of wall shear stress that involves calcium efflux and stimulation of the prostaglandin E2 (PGE2)-cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) signaling axis. Blockade of the PGE2-cAMP-PKA pathway in the aorta-gonad-mesonephros (AGM) abolished enhancement in hematopoietic activity. Furthermore, Ncx1 heartbeat mutants, as well as static cultures of AGM, exhibit lower levels of expression of prostaglandin synthases and reduced phosphorylation of the cAMP response element-binding protein (CREB). Similar to flow-exposed cultures, transient treatment of AGM with the synthetic analogue 16,16-dimethyl-PGE2 stimulates more robust engraftment of adult recipients and greater lymphoid reconstitution. These data provide one mechanism by which biomechanical forces induced by blood flow modulate hematopoietic potential.

  13. Development and implementation of a coupled computational muscle force optimization bone shape adaptation modeling method.

    PubMed

    Florio, C S

    2015-04-01

    Improved methods to analyze and compare the muscle-based influences that drive bone strength adaptation can aid in the understanding of the wide array of experimental observations about the effectiveness of various mechanical countermeasures to losses in bone strength that result from age, disuse, and reduced gravity environments. The coupling of gradient-based and gradientless numerical optimization routines with finite element methods in this work results in a modeling technique that determines the individual magnitudes of the muscle forces acting in a multisegment musculoskeletal system and predicts the improvement in the stress state uniformity and, therefore, strength, of a targeted bone through simulated local cortical material accretion and resorption. With a performance-based stopping criteria, no experimentally based or system-based parameters, and designed to include the direct and indirect effects of muscles attached to the targeted bone as well as to its neighbors, shape and strength alterations resulting from a wide range of boundary conditions can be consistently quantified. As demonstrated in a representative parametric study, the developed technique effectively provides a clearer foundation for the study of the relationships between muscle forces and the induced changes in bone strength. Its use can lead to the better control of such adaptive phenomena.

  14. Development of Velocity Guidance Assistance System by Haptic Accelerator Pedal Reaction Force Control

    NASA Astrophysics Data System (ADS)

    Yin, Feilong; Hayashi, Ryuzo; Raksincharoensak, Pongsathorn; Nagai, Masao

    This research proposes a haptic velocity guidance assistance system for realizing eco-driving as well as enhancing traffic capacity by cooperating with ITS (Intelligent Transportation Systems). The proposed guidance system generates the desired accelerator pedal (abbreviated as pedal) stroke with respect to the desired velocity obtained from ITS considering vehicle dynamics, and provides the desired pedal stroke to the driver via a haptic pedal whose reaction force is controllable and guides the driver in order to trace the desired velocity in real time. The main purpose of this paper is to discuss the feasibility of the haptic velocity guidance. A haptic velocity guidance system for research is developed on the Driving Simulator of TUAT (DS), by attaching a low-inertia, low-friction motor to the pedal, which does not change the original characteristics of the original pedal when it is not operated, implementing an algorithm regarding the desired pedal stroke calculation and the reaction force controller. The haptic guidance maneuver is designed based on human pedal stepping experiments. A simple velocity profile with acceleration, deceleration and cruising is synthesized according to naturalistic driving for testing the proposed system. The experiment result of 9 drivers shows that the haptic guidance provides high accuracy and quick response in velocity tracking. These results prove that the haptic guidance is a promising velocity guidance method from the viewpoint of HMI (Human Machine Interface).

  15. 75 FR 62438 - Interagency Task Force on Veterans Small Business Development Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-08

    ... No: 2010-25455] SMALL BUSINESS ADMINISTRATION Interagency Task Force on Veterans Small Business... Task Force Meeting. SUMMARY: The SBA is issuing this notice to announce the location, date, time, and agenda for the first public meeting of the Interagency Task Force on Veterans Small Business...

  16. Use of a Mobile Application to Help Students Develop Skills Needed in Solving Force Equilibrium Problems

    ERIC Educational Resources Information Center

    Yang, Eunice

    2016-01-01

    This paper discusses the use of a free mobile engineering application (app) called Autodesk® ForceEffect™ to provide students assistance with spatial visualization of forces and more practice in solving/visualizing statics problems compared to the traditional pencil-and-paper method. ForceEffect analyzes static rigid-body systems using free-body…

  17. 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

  18. 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

  19. Associations between rate of force development metrics and throwing velocity in elite team handball players: a short research report.

    PubMed

    Marques, Mário C; Saavedra, Francisco J; Abrantes, Catarina; Aidar, Felipe J

    2011-09-01

    Performance assessment has become an invaluable component of monitoring participant's development in distinct sports, yet limited and contradictory data are available in trained subjects. The purpose of this study was to examine the relationship between ball throwing velocity during a 3-step running throw in elite team handball players and selected measures of rate of force development like force, power, velocity, and bar displacement during a concentric only bench press exercise in elite male handball players. Fitteen elite senior male team handball players volunteered to participate. Each volunteer had power and bar velocity measured during a concentric only bench press test with 25, 35, and 45 kg as well as having one-repetition maximum strength determined. Ball throwing velocity was evaluated with a standard 3-step running throw using a radar gun. The results of this study indicated significant associations between ball velocity and time at maximum rate of force development (0, 66; p<0.05) and rate of force development at peak force (0,56; p<0.05) only with 25kg load. The current research indicated that ball velocity was only median associated with maximum rate of force development with light loads. A training regimen designed to improve ball-throwing velocity in elite male team handball players should emphasize bench press movement using light loads.

  20. Associations Between Rate of Force Development Metrics and Throwing Velocity in Elite Team Handball Players: a Short Research Report

    PubMed Central

    Marques, Mário C.; Saavedra, Francisco J.; Abrantes, Catarina; Aidar, Felipe J.

    2011-01-01

    Performance assessment has become an invaluable component of monitoring participant’s development in distinct sports, yet limited and contradictory data are available in trained subjects. The purpose of this study was to examine the relationship between ball throwing velocity during a 3-step running throw in elite team handball players and selected measures of rate of force development like force, power, velocity, and bar displacement during a concentric only bench press exercise in elite male handball players. Fitteen elite senior male team handball players volunteered to participate. Each volunteer had power and bar velocity measured during a concentric only bench press test with 25, 35, and 45 kg as well as having one-repetition maximum strength determined. Ball throwing velocity was evaluated with a standard 3-step running throw using a radar gun. The results of this study indicated significant associations between ball velocity and time at maximum rate of force development (0, 66; p<0.05) and rate of force development at peak force (0,56; p<0.05) only with 25kg load. The current research indicated that ball velocity was only median associated with maximum rate of force development with light loads. A training regimen designed to improve ball-throwing velocity in elite male team handball players should emphasize bench press movement using light loads. PMID:23487363

  1. CHARMM Force Field Parameterization of Peroxisome Proliferator-Activated Receptor γ Ligands

    PubMed Central

    Mottin, Melina; Souza, Paulo C. T.; Ricci, Clarisse G.; Skaf, Munir S.

    2016-01-01

    The peroxisome proliferator-activated receptor γ (PPARγ) ligands are important therapeutic drugs for the treatment of type 2 diabetes, obesity and cardiovascular diseases. In particular, partial agonists and non-agonists are interesting targets to reduce glucose levels, presenting few side effects in comparison to full agonists. In this work, we present a set of CHARMM-based parameters of a molecular mechanics force field for two PPARγ ligands, GQ16 and SR1664. GQ16 belongs to the thiazolidinedione class of drugs and it is a PPARγ partial agonist that has been shown to promote the “browning” of white adipose tissue. SR1664 is the precursor of the PPARγ non-agonist class of ligands that activates PPARγ in a non-classical manner. Here, we use quantum chemical calculations consistent with the CHARMM protocol to obtain bonded and non-bonded parameters, including partial atomic charges and effective torsion potentials for both molecules. The newly parameterized models were evaluated by examining the behavior of GQ16 and SR1664 free in water and bound to the ligand binding pocket of PPARγ using molecular dynamics simulations. The potential parameters derived here are readily transferable to a variety of pharmaceutical compounds and similar PPARγ ligands. PMID:28025495

  2. Tuberculosis trends in the U.S. Armed Forces, active component, 1998-2012.

    PubMed

    Mancuso, James D; Aaron, Christopher L

    2013-05-01

    Members of the Armed Forces represent a segment of the U.S. population that may be at increased risk for tuberculosis (TB) infection, disease, and transmission due to overseas service in endemic areas and residence in congregate settings. The purpose of this study was to examine recent surveillance trends and risk factors associated with TB disease in the active component U.S. military. The rate of TB in the U.S. military -0.6 per 100,000 population (n=128) over the interval from 1998 to 2012 - was lower than the age-adjusted rate among the U.S. population (adjusted rate ratio=0.20) over the same time interval. During the last five years of the surveillance period, the most common factor associated with the diagnosis of TB disease during military service was latent infection at time of accession; also, as many as nine (24%) cases of TB were associated with deployment to Iraq or other military exposures. TB control activities should continue to mitigate unique military exposures such as crowding during recruit training and deployments to TB endemic areas.

  3. Dynamic myosin activation promotes collective morphology and migration by locally balancing oppositional forces from surrounding tissue.

    PubMed

    Aranjuez, George; Burtscher, Ashley; Sawant, Ketki; Majumder, Pralay; McDonald, Jocelyn A

    2016-06-15

    Migrating cells need to overcome physical constraints from the local microenvironment to navigate their way through tissues. Cells that move collectively have the additional challenge of negotiating complex environments in vivo while maintaining cohesion of the group as a whole. The mechanisms by which collectives maintain a migratory morphology while resisting physical constraints from the surrounding tissue are poorly understood. Drosophila border cells represent a genetic model of collective migration within a cell-dense tissue. Border cells move as a cohesive group of 6-10 cells, traversing a network of large germ line-derived nurse cells within the ovary. Here we show that the border cell cluster is compact and round throughout their entire migration, a shape that is maintained despite the mechanical pressure imposed by the surrounding nurse cells. Nonmuscle myosin II (Myo-II) activity at the cluster periphery becomes elevated in response to increased constriction by nurse cells. Furthermore, the distinctive border cell collective morphology requires highly dynamic and localized enrichment of Myo-II. Thus, activated Myo-II promotes cortical tension at the outer edge of the migrating border cell cluster to resist compressive forces from nurse cells. We propose that dynamic actomyosin tension at the periphery of collectives facilitates their movement through restrictive tissues.

  4. Transfer and Use of Training Technology in Air Force Technical Training: A Model to Guide Training Development. Final Report.

    ERIC Educational Resources Information Center

    Haverland, Edgar M.

    This guide describes the final stage in a project to develop an Air Force technical training development model and presents the model. Chapter 1 summarizes the total project and its objective to facilitate the effective use of training technology through the development of a model for matching training approaches or innovations with specific…

  5. Development of optical fiber Bragg grating force-reflection sensor system of medical application for safe minimally invasive robotic surgery

    NASA Astrophysics Data System (ADS)

    Song, Hoseok; Kim, Kiyoung; Lee, Jungju

    2011-07-01

    Force feedback plays a very important role in medical surgery. In minimally invasive surgery (MIS), however, the very long and stiff bars of surgical instruments greatly diminish force feedback for the surgeon. In the case of minimally invasive robotic surgery (MIRS), force feedback is totally eliminated. Previous researchers have reported that the absence of force feedback increased the average force magnitude applied to the tissue by at least 50%, and increased the peak force magnitude by at least a factor of two. Therefore, it is very important to provide force information in MIRS. Recently, many sensors are being developed for MIS and MIRS, but some obstacles to their application in actual medical surgery must be surmounted. The most critical problems are size limit and sterilizability. Optical fiber sensors are among the most suitable sensors for the surgical environment. The optical fiber Bragg grating (FBG) sensor, in particular, offers an important additional advantage over other optical fiber sensors in that it is not influenced by the intensity of the light source. In this paper, we present the initial results of a study on the application of a FBG sensor to measure reflected forces in MIRS environments and suggest the possibility of successful application to MIRS systems.

  6. Effects of corrugation angle on developing laminar forced convection and entropy generation in a wavy channel

    NASA Astrophysics Data System (ADS)

    Ko, Tzu-Hsiang

    2007-12-01

    This paper investigates the effects of corrugation angle ( β) on the developing laminar forced convection and entropy generation in a wavy channel with numerical methods. The studied cases cover β = 10-, 15-, 20-, 25-, 30- and 35°, whilst Reynolds number ( Re) is varied as 100, 200 and 400. The analyzed flow characteristics include recirculating flows, secondary vortices, temperature distributions, and friction factor as well as Nusselt number. In particular, the effects of corrugation angle on the distributions and magnitudes of local entropy generation resulted from frictional irreversibility ( S {/P '''}) and heat transfer irreversibility ( S {/T '''}) are separately discussed in detail in the present paper. Based on the minimal entropy generation principle, the optimal corrugation angle and favorable Re are reported.

  7. The Future of Officer Career Development System in the Slovenian Armed Forces

    DTIC Science & Technology

    2013-12-13

    directs and supports others in both routine activities and under stress; and he instills self - esteem , team spirit and unity of effort through developing...Competencies are defined as activation and connection of individual knowledge, capabilities, motivation, self -awareness and values, which allows an...strategic mission.11 Officer Corps. ‘’This is the body of commissioned officers imbued with a unique self -concept defined by the following four

  8. Internal development of vegetative buds of Norway spruce trees in relation to accumulated chilling and forcing temperatures.

    PubMed

    Viherä-Aarnio, Anneli; Sutinen, Sirkka; Partanen, Jouni; Häkkinen, Risto

    2014-05-01

    The timing of budburst of temperate trees is known to be controlled by complicated interactions of temperature and photoperiod. To improve the phenological models of budburst, better knowledge of the internal bud development preceding budburst in relation to environmental cues is needed. We studied the effect of accumulated chilling and forcing temperatures on the internal development of vegetative buds preceding budburst in Norway spruce [Picea abies (L.) Karst.]. Branches from 17-year-old trees of southern Finnish origin were transferred eight times at 1- to 2-week intervals from October to December 2007 from the field at Punkaharju (61°48'N, 29°20'E) to the greenhouse with forcing conditions (day length 12 h, +20 °C). After seven different durations of forcing, the developmental phase and primordial shoot growth of the buds were analysed at the stereomicroscopic level. Air temperature was recorded hourly throughout the study period. The accumulated chilling unit sum had a significant effect on the temperature sum that was required to attain a certain developmental phase; a higher amount of chilling required a lower amount of forcing. The variation in the rate of development of different buds within each sample branch in relation to the chilling unit and forcing temperature sum was low. Regarding primordial shoot growth, there was also an inverse relation between accumulated chilling and forcing, i.e., a higher accumulated chilling unit sum before forcing required a lower temperature sum to initiate primordial shoot growth and resulted in a stronger effect of accumulated forcing. A second-order regression model with an interaction of chilling and forcing explained the variation of primordial shoot growth with high precision (R(2) = 0.88). However, further studies are required to determine the final parameter values to be used in phenological modelling.

  9. Task III: Development of an Effective Computational Methodology for Body Force Representation of High-speed Rotor 37

    NASA Technical Reports Server (NTRS)

    Tan, Choon-Sooi; Suder, Kenneth (Technical Monitor)

    2003-01-01

    A framework for an effective computational methodology for characterizing the stability and the impact of distortion in high-speed multi-stage compressor is being developed. The methodology consists of using a few isolated-blade row Navier-Stokes solutions for each blade row to construct a body force database. The purpose of the body force database is to replace each blade row in a multi-stage compressor by a body force distribution to produce same pressure rise and flow turning. To do this, each body force database is generated in such a way that it can respond to the changes in local flow conditions. Once the database is generated, no hrther Navier-Stokes computations are necessary. The process is repeated for every blade row in the multi-stage compressor. The body forces are then embedded as source terms in an Euler solver. The method is developed to have the capability to compute the performance in a flow that has radial as well as circumferential non-uniformity with a length scale larger than a blade pitch; thus it can potentially be used to characterize the stability of a compressor under design. It is these two latter features as well as the accompanying procedure to obtain the body force representation that distinguish the present methodology from the streamline curvature method. The overall computational procedures have been developed. A dimensional analysis was carried out to determine the local flow conditions for parameterizing the magnitudes of the local body force representation of blade rows. An Euler solver was modified to embed the body forces as source terms. The results from the dimensional analysis show that the body forces can be parameterized in terms of the two relative flow angles, the relative Mach number, and the Reynolds number. For flow in a high-speed transonic blade row, they can be parameterized in terms of the local relative Mach number alone.

  10. Preliminary development of the Active Colonoscopy Training Model

    PubMed Central

    Choi, JungHun; Ravindra, Kale; Robert, Randolph; Drozek, David

    2011-01-01

    Formal colonoscopy training requires a significant amount of time and effort. In particular, it requires actual patients for a realistic learning experience. The quality of colonoscopy training varies, and includes didactic courses and procedures proctored by skilled surgeons. A colonoscopy training model is occasionally used as part of the training method, but the effects are minute due to both the simple and tedious training procedures. To enhance the educational effect of the colonoscopy training model, the Active Colonoscopy Training Model (ACTM) has been developed. ACTM is an interactive colonoscopy training device which can create the environment of a real colonoscopy procedure as closely as possible. It comprises a configurable rubber colon, a human torso, sensors, a display, and the control part. The ACTM provides audio and visual interaction to the trainee by monitoring important factors, such as forces caused by the distal tip and the shaft of the colonoscope and the pressure to open up the lumen and the localization of the distal tip. On the computer screen, the trainee can easily monitor the status of the colonoscopy, which includes the localization of the distal tip, maximum forces, pressure inside the colon, and surgery time. The forces between the rubber colon and the constraints inside the ACTM are measured and the real time display shows the results to the trainee. The pressure sensors will check the pressure at different parts of the colon. The real-time localized distal tip gives the colonoscopy trainee easier and more confident operation without introducing an additional device in the colonoscope. With the current need for colonoscopists and physicians, the ACTM can play an essential role resolving the problems of the current colonoscopy training model, and significantly improve the training quality of the colonoscopy. PMID:22915931

  11. An Energetic Perspective on Aerosol Radiative Forcing and Interactions with Atmospheric Wave Activity

    NASA Astrophysics Data System (ADS)

    Hosseinpour, F.; Wilcox, E. M.; Colarco, P. R.

    2014-12-01

    Aerosols have the capability to alter regional-scale atmospheric circulations. A better understanding of the contribution of aerosols to multi-scale atmospheric phenomena and their transient changes is crucial for efforts to evaluate climate predictions using next generation climate models. In this study we address the following questions: (1) Is there a mechanistic relationship between variability of oceanic dust aerosol forcing and transient changes in the African easterly jet- African easterly wave (AEJ-AEW) system? (2) What are the long-term impacts of possible aerosol-wave interactions on climate dynamics of eastern tropical Atlantic Ocean and western African monsoon (WAM) region during boreal summer seasons? Our hypothesis is that aerosol radiative forcing may act as additional energy source to fuel the development of African easterly waves on the northern and southern sides of the AEJ. Evidence in support of this hypothesis is presented based on analysis of an ensemble of NASA satellite data sets, including aerosol optical thickness (AOT) observations from the Moderate Resolution Imaging Spectro-radiometer (MODIS) and the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS), as well as an atmospheric reanalysis from the Modern-Era Retrospective Analysis for Research and Applications (MERRA) and a simulation of global aerosol distributions made with the Goddard Earth Observing System Model version 5 (GEOS-5) Earth system model with meteorology constrained by MERRA and an assimilation of MODIS AOT (MERRAero). We propose that the impacts of Saharan aerosols on the regional climate dynamics occur through contributions to the eddy energy of waves with 2—7-day and 7—11-day variability.

  12. Labor Force

    ERIC Educational Resources Information Center

    Occupational Outlook Quarterly, 2010

    2010-01-01

    The labor force is the number of people aged 16 or older who are either working or looking for work. It does not include active-duty military personnel or institutionalized people, such as prison inmates. Quantifying this total supply of labor is a way of determining how big the economy can get. Labor force participation rates vary significantly…

  13. 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.

  14. An attempt to monitor tectonic forces in the Vrancea active geodynamic zone: The Baspunar experiment

    NASA Astrophysics Data System (ADS)

    Besutiu, Lucian; Zlagnean, Luminita; Plopeanu, Marin

    2013-04-01

    An alternative model attempting to explain the unusual sub-crustal seismicity occurring in the bending zone of East Carpathians within full intra-continental environment (the so-called Vrancea zone) has assumed the presence of a FFT unstable triple junction between the three lithospheric compartments joining the area: East European Plate (EEP), Intra-Alpine Microplate (IaP) and the Moesian Microplate (MoP). Geophysical imprints (e.g. EM data, potential fields, seismic tomography), and indirect geological evidence (e.g. absence of the volcanism associated to subduction zones, the unusual high Neogene tectonic subsidence, symmetry and normal faulting within compressional environment of Focsani basin) support the hypothesis. The above-mentioned model considers the intermediate-depth seismicity as the result of the thermo-baric-accommodation phenomena generated within the colder lithosphere collapsed into the hotter upper mantle. Therefore, the amount of seismic energy thus released should be related to the volume of the lithosphere brought into thermo-baric disequilibrium by sinking into the upper mantle. Vertical dynamics of the Vrancea unstable triple junction (VTJ) seems to be controlled by the both tangential tectonic forces driving the neighbouring plates and the gravitational pull created by the eclogitization of VTJ lower crust. But, while eclogitization provides a relatively constant force, acceleration of sinking is expected to be provided by changes in the tectonic forces acting on VTJ. As changes in tectonic forces should reflect in changes of the dynamics of lithospheric compartments, geodetic means were considered for helping in their monitoring. The Peceneaga-Camena Fault (PCF) is a major lithospheric contact separating MoP and EEP, starting from the W Black Sea basin to the Vrancea zone. Geological evidence advocate for its variable geodynamic behaviour during the time, both as left-lateral or right-lateral fault. Unfortunately, GPS campaigns, so far

  15. The ReaxFF reactive force-field: Development, applications, and future directions

    SciTech Connect

    Senftle, Thomas; Hong, Sungwook; Islam, Md Mahbubul; Kylasa, Sudhir; Zheng, Yuanzia; Shin, Yun Kyung; Junkermeier, Chad; Engel-Herbert, Roman; Janik, Michael J.; Aktulga, Hasan Metin; Verstraelen, Toon; Grama, Ananth; Adri C. T. van Duin

    2016-03-04

    The reactive force-field (ReaxFF) interatomic potential is a powerful computational tool for exploring, developing and optimizing material properties. Methods based on the principles of quantum mechanics (QM), while offering valuable theoretical guidance at the electronic level, are often too computationally intense for simulations that consider the full dynamic evolution of a system. Alternatively, empirical interatomic potentials that are based on classical principles require significantly fewer computational resources, which enables simulations to better describe dynamic processes over longer timeframes and on larger scales. Such methods, however, typically require a predefined connectivity between atoms, precluding simulations that involve reactive events. The ReaxFF method was developed to help bridge this gap. Approaching the gap from the classical side, ReaxFF casts the empirical interatomic potential within a bond-order formalism, thus implicitly describing chemical bonding without expensive QM calculations. As a result, this article provides an overview of the development, application, and future directions of the ReaxFF method.

  16. The ReaxFF reactive force-field: Development, applications, and future directions

    DOE PAGES

    Senftle, Thomas; Hong, Sungwook; Islam, Md Mahbubul; ...

    2016-03-04

    The reactive force-field (ReaxFF) interatomic potential is a powerful computational tool for exploring, developing and optimizing material properties. Methods based on the principles of quantum mechanics (QM), while offering valuable theoretical guidance at the electronic level, are often too computationally intense for simulations that consider the full dynamic evolution of a system. Alternatively, empirical interatomic potentials that are based on classical principles require significantly fewer computational resources, which enables simulations to better describe dynamic processes over longer timeframes and on larger scales. Such methods, however, typically require a predefined connectivity between atoms, precluding simulations that involve reactive events. The ReaxFFmore » method was developed to help bridge this gap. Approaching the gap from the classical side, ReaxFF casts the empirical interatomic potential within a bond-order formalism, thus implicitly describing chemical bonding without expensive QM calculations. As a result, this article provides an overview of the development, application, and future directions of the ReaxFF method.« less

  17. Assessment of U.S. Government Efforts to Develop the Logistics Sustainment Capability of the Iraq Security Forces

    DTIC Science & Technology

    2010-11-17

    the Iraqi police forces and military services. • Iraqi investment in human capital development for establishing an enduring logistics capability...for the Iraqi military. Investment in Human Capital With the assistance of USF-I A&T, the Iraqi Air Force, Navy, and Army have made an investment...in human capital that will help to establish an enduring logistics capability in those Services.  45 courses are being taught by qualified Iraqi

  18. Kelvin probe force microscopy for local characterisation of active nanoelectronic devices

    PubMed Central

    Beyer, Hannes; Reissner, Patrick; Mensch, Philipp; Riel, Heike; Gotsmann, Bernd

    2015-01-01

    Summary Frequency modulated Kelvin probe force microscopy (FM-KFM) is the method of choice for high resolution measurements of local surface potentials, yet on coarse topographic structures most researchers revert to amplitude modulated lift-mode techniques for better stability. This approach inevitably translates into lower lateral resolution and pronounced capacitive averaging of the locally measured contact potential difference. Furthermore, local changes in the strength of the electrostatic interaction between tip and surface easily lead to topography crosstalk seen in the surface potential. To take full advantage of the superior resolution of FM-KFM while maintaining robust topography feedback and minimal crosstalk, we introduce a novel FM-KFM controller based on a Kalman filter and direct demodulation of sidebands. We discuss the origin of sidebands in FM-KFM irrespective of the cantilever quality factor and how direct sideband demodulation enables robust amplitude modulated topography feedback. Finally, we demonstrate our single-scan FM-KFM technique on an active nanoelectronic device consisting of a 70 nm diameter InAs nanowire contacted by a pair of 120 nm thick electrodes. PMID:26734511

  19. Active control of the forced and transient response of a finite beam. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Post, John T.

    1990-01-01

    Structural vibrations from a point force are modelled on a finite beam. This research explores the theoretical limit on controlling beam vibrations utilizing another point source as an active controller. Three different types of excitation are considered, harmonic, random, and transient. For harmonic excitation, control over the entire beam length is possible only when the excitation frequency is near a resonant frequency of the beam. Control over a subregion may be obtained even between resonant frequencies at the cost of increasing the vibration outside of the control region. For random excitation, integrating the expected value of the displacement squared over the required interval, is shown to yield the identical cost function as obtained by integrating the cost function for harmonic excitation over all excitation frequencies. As a result, it is always possible to reduce the cost function for random excitation whether controlling the entire beam or just a subregion, without ever increasing the vibration outside the region in which control is desired. The last type of excitation considered is a single, transient pulse. The form of the controller is specified as either one or two delayed pulses, thus constraining the controller to be casual. The best possible control is examined while varying the region of control and the controller location. It is found that control is always possible using either one or two control pulses.

  20. Bacterial skin infections, active component, U.S. Armed Forces, 2000-2012.

    PubMed

    2013-12-01

    From 2000 through 2012, health care records of the Military Health System documented 998,671 incident cases of bacterial skin infections among active component members of the U.S. Armed Forces. Most cases (97.3%) were identified from records of outpatient medical encounters rather than hospitalizations. Cellulitis accounted for half (50.9%) of all cases of bacterial skin infection but 96 percent of associated hospital bed days. Of all cases, 42.3 percent were "other" skin infections (i.e., folliculitis, impetigo, pyoderma, pyogenic granuloma, other and unspecified infections). The remainder were attributable to carbuncles/furuncles (6.6%) and erysipelas (0.1%). Rates of infection were higher among female service members except for "other" skin infections. In general, the highest rates were associated with youth, recruit trainee status, and junior enlisted rank; however, rates of erysipelas were highest among those 50 years and older. Annual incidence rates of all bacterial skin infections have increased greatly since 2000. During the entire period, such infections required more than 1.4 million health care encounters and 94,000 hospital bed-days (equivalent to 257 years of lost duty time). The prevention, early diagnosis, and treatment of bacterial skin infections, particularly in high risk settings, deserve continued emphasis.

  1. Gastrointestinal infections, active component, U.S. Armed Forces, 2002-2012.

    PubMed

    2013-10-01

    Acute gastroenteritis and other infectious disorders of the gastrointestinal system are common in civilian and military populations. During the years 2002 through 2012, there were 286,305 cases of gastrointestinal infection (GI) diagnosed among members of the active component of the U.S. Armed Forces. The distribution of presumed causes of these illnesses (as reported in administrative medical records) was bacterial (29%), viral (68%), and parasitic (3%). Most recorded diagnoses did not specify an etiologic agent. In addition, there were 379,509 other healthcare encounters in which the recorded diagnosis was simply "diarrhea." During the period, rates of hospitalization for Clostridium difficile and "ill-defined intestinal infection" increased greatly. In the outpatient setting, rates of GI diagnoses remained stable or declined, but rates of non-specific "diarrhea" increased steadily. Among reportable infectious causes of GI, rates of both campylobacteriosis and norovirus diagnoses increased steadily since 2009. Among deployed service members with GI during the period 2005 through 2012, viral agents were most often recorded as the underlying etiology (60%). Salmonellosis was the most frequent specific bacterial etiology diagnosed among deployed service members. Countermeasures against GI among service member should be emphasized in military education programs at all levels, during field training exercises, and particularly in deployment settings.

  2. Arm and shoulder conditions, active component, U.S. Armed Forces, 2003-2012.

    PubMed

    2013-06-01

    This analysis estimated the incidence and health care burden of acute and chronic conditions of the arm and shoulder among active component service members of the Armed Forces from 1 January 2003 through 31 December 2012. There were 196,789 diagnosed incident cases of acute arm and shoulder conditions for a rate of 13.7 cases per 1,000 person-years. The annual incidence rates of sprains, the most common acute condition, nearly doubled during the period. Diagnoses of chronic conditions (overall rate of 28.8 per 1,000 person-years) increased 25 percent during the period, mainly associated with a doubling of the incidence of diagnoses of joint pain. Incidence rates of chronic disorders were progressively higher among successively older age groups of service members. The health care burden of all arm and shoulder conditions together steadily increased during the period, as indicated by numbers of health care encounters, individuals affected, and lost work time. The most commonly documented causes associated with acute and chronic conditions are described.

  3. Incident diagnoses of leishmaniasis, active and reserve components, U.S. Armed Forces, 2001-2016.

    PubMed

    Stahlman, Shauna; Williams, Valerie F; Taubman, Stephen B

    2017-02-01

    During the surveillance period, there were 2,040 incident diagnoses/reports of leishmaniasis among members of the U.S. Armed Forces. Cutaneous leishmaniasis accounted for more than three-fifths (61.0%) of the total diagnoses/ reports among active component service members and for less than half (48.0%) of the total cases among reserve component members. The visceral form of leishmaniasis represented 1.2% of the total cases. Approximately two-fifths (40.6%) of the total diagnoses/reports were classified as "unspecified" with respect to the type of leishmaniasis. The lowest annual numbers of diagnoses/reports in the past decade were seen in 2011-2016 and reached a nadir of 11 cases in 2015. During the entire surveillance period, 71.7% of the total leishmaniasis cases were diagnosed or reported during the 7 months from early autumn to the beginning of spring (September-March) in the northern hemisphere. The majority of cases acquired in the Middle East (73.6%), South/Central America (87.5%), and other or unknown locations (64.5%) were diagnosed or reported during this 7-month interval.

  4. 24 CFR 968.120 - Force account.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Force account. 968.120 Section 968... PUBLIC HOUSING MODERNIZATION General § 968.120 Force account. (a) For both CIAP and CGP, a PHA may undertake the activities using force account labor, only where specifically approved by HUD in the...

  5. 24 CFR 968.120 - Force account.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 4 2011-04-01 2011-04-01 false Force account. 968.120 Section 968... PUBLIC HOUSING MODERNIZATION General § 968.120 Force account. (a) For both CIAP and CGP, a PHA may undertake the activities using force account labor, only where specifically approved by HUD in the...

  6. 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

  7. Shelfal sediment transport by undercurrents forces turbidity current activity during high sea level, Chile continental margin

    NASA Astrophysics Data System (ADS)

    Bernhardt, Anne; Hebbeln, Dierk; Regenberg, Marcus; Lückge, Andreas; Strecker, Manfred. R.

    2016-04-01

    Understanding the links between terrigenous sediment supply and marine transport and depositional processes along tectonically active margins is essential to decipher turbidite successions as potential archives of climatic and seismic forcings and to comprehend timing and quantity of marine clastic deposition. Sequence stratigraphic models predict coarse-grained terrigenous sediment delivery to deep-marine sites mainly during sea-level fall and lowstand. Marine clastic deposition during periods of transgression and highstand has been attributed to the continued geomorphic connectivity between terrestrial sediment sources and marine sinks (e.g., rivers connected to submarine canyons) often facilitated by narrow shelves, high sediment supply causing delta migration to the shelf edge, and/or abrupt increases in sediment supply due to climatic variability or catastrophic events. To decipher the controls on Holocene highstand turbidite deposition, we analyzed twelve sediment cores of spatially disparate, coeval Holocene turbidite systems along the Chile margin (29-40°S) with changing climatic and geomorphic characteristics but uniform changes of sea level. Intraslope basins in north-central Chile (29-33°S) offshore a narrow to absent shelf record a shut-off of turbidite activity during the Holocene. In contrast, core sites in south-central Chile (36-40°S) offshore a wide continental shelf have repeatedly experienced turbidite deposition during sea-level highstand conditions, even though most of the depocenters are not connected via canyons to sediment sources. The interplay of stable high sediment supply related to strong onshore precipitation in combination with a wide shelf, over which undercurrents move sediment towards the shelf edge, appears to control Holocene turbidite sedimentation and sediment export to the deep sea.

  8. 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.

  9. Development of a hybrid atomic force microscopic measurement system combined with white light scanning interferometry.

    PubMed

    Guo, Tong; Wang, Siming; Dorantes-Gonzalez, Dante J; Chen, Jinping; Fu, Xing; Hu, Xiaotang

    2012-01-01

    A hybrid atomic force microscopic (AFM) measurement system combined with white light scanning interferometry for micro/nanometer dimensional measurement is developed. The system is based on a high precision large-range positioning platform with nanometer accuracy on which a white light scanning interferometric module and an AFM head are built. A compact AFM head is developed using a self-sensing tuning fork probe. The head need no external optical sensors to detect the deflection of the cantilever, which saves room on the head, and it can be directly fixed under an optical microscopic interferometric system. To enhance the system's dynamic response, the frequency modulation (FM) mode is adopted for the AFM head. The measuring data can be traceable through three laser interferometers in the system. The lateral scanning range can reach 25 mm × 25 mm by using a large-range positioning platform. A hybrid method combining AFM and white light scanning interferometry is proposed to improve the AFM measurement efficiency. In this method, the sample is measured firstly by white light scanning interferometry to get an overall coarse morphology, and then, further measured with higher resolution by AFM. Several measuring experiments on standard samples demonstrate the system's good measurement performance and feasibility of the hybrid measurement method.

  10. Learning about Modes in Atomic Force Microscopy by Means of Hands-On Activities Based on a Simple Apparatus

    ERIC Educational Resources Information Center

    Phuapaiboon, Unchada; Panijpan, Bhinyo; Osotchan, Tanakorn

    2009-01-01

    This study was conducted to examine the results of using a low-cost hands-on setup in combination with accompanying activities to promote understanding of the contact mode of atomic force microscopy (AFM). This contact mode setup enabled learners to study how AFM works by hand scanning using probing cantilevers with different characteristics on…

  11. Formation and eruption of an active region sigmoid. I. A study by nonlinear force-free field modeling

    SciTech Connect

    Jiang, Chaowei; Feng, Xueshang; Wu, S. T.; Hu, Qiang E-mail: fengx@spaceweather.ac.cn E-mail: qh0001@uah.edu

    2014-01-01

    We present a comprehensive study of the formation and eruption of an active region (AR) sigmoid in AR 11283. To follow the quasi-static evolution of the coronal magnetic field, we reconstruct a time sequence of static fields using a recently developed nonlinear force-free field model constrained by vector magnetograms. A detailed analysis of the fields compared with observations suggests the following scenario for the evolution of the region. Initially, a new bipole emerges into the negative polarity of a preexisting bipolar AR, forming a null-point topology between the two flux systems. A weakly twisted flux rope (FR) is then built up slowly in the embedded core region, largely through flux cancellation, forming a bald patch separatrix surface (BPSS). The FR grows gradually until its axis runs into a torus instability (TI) domain, and the BPSS also develops a full S-shape. The combined effects of the TI-driven expansion of the FR and the line tying at the BP tear the FR into two parts with the upper portion freely expelled and the lower portion remaining behind the postflare arcades. This process dynamically perturbs the BPSS and results in the enhanced heating of the sigmoid and the rope. The accelerated expansion of the upper-portion rope strongly pushes its envelope flux near the null point and triggers breakout reconnection at the null, which further drives the eruption. We discuss the important implications of these results for the formation and disruption of the sigmoid region with an FR.

  12. Formation and Eruption of an Active Region Sigmoid. I. A Study by Nonlinear Force-free Field Modeling

    NASA Astrophysics Data System (ADS)

    Jiang, Chaowei; Wu, S. T.; Feng, Xueshang; Hu, Qiang

    2014-01-01

    We present a comprehensive study of the formation and eruption of an active region (AR) sigmoid in AR 11283. To follow the quasi-static evolution of the coronal magnetic field, we reconstruct a time sequence of static fields using a recently developed nonlinear force-free field model constrained by vector magnetograms. A detailed analysis of the fields compared with observations suggests the following scenario for the evolution of the region. Initially, a new bipole emerges into the negative polarity of a preexisting bipolar AR, forming a null-point topology between the two flux systems. A weakly twisted flux rope (FR) is then built up slowly in the embedded core region, largely through flux cancellation, forming a bald patch separatrix surface (BPSS). The FR grows gradually until its axis runs into a torus instability (TI) domain, and the BPSS also develops a full S-shape. The combined effects of the TI-driven expansion of the FR and the line tying at the BP tear the FR into two parts with the upper portion freely expelled and the lower portion remaining behind the postflare arcades. This process dynamically perturbs the BPSS and results in the enhanced heating of the sigmoid and the rope. The accelerated expansion of the upper-portion rope strongly pushes its envelope flux near the null point and triggers breakout reconnection at the null, which further drives the eruption. We discuss the important implications of these results for the formation and disruption of the sigmoid region with an FR.

  13. 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.

  14. Control of forces applied by individual fingers engaged in restraint of an active object.

    PubMed

    Burstedt, M K; Birznieks, I; Edin, B B; Johansson, R S

    1997-07-01

    We investigated the coordination of fingertip forces in subjects who used the tips of two fingers to restrain an instrumented manipulandum with horizontally oriented grip surfaces. The grip surfaces were subjected to tangential pulling forces in the distal direction in relation to the fingers. The subjects used either the right index and middle fingers (unimanual grasp) or both index fingers (bimanual grasp) to restrain the manipulandum. To change the frictional condition at the digit-object interfaces, either both grip surfaces were covered with sandpaper or one was covered with sandpaper and the other with rayon. The forces applied normally and tangentially to the grip surfaces were measured separately at each plate along with the position of the plates. Subjects could have performed the present task successfully with many different force distributions between the digits. However, they partitioned the load in a manner that reflected the frictional condition at the local digit-object interfaces. When both digits contacted sandpaper, they typically partitioned the load symmetrically, but when one digit made contact with rayon and the other with sandpaper, the digit contacting the less slippery material (sandpaper) took up a larger part of the load. The normal forces were also influenced by the frictional condition, but they reflected the average friction at the two contact sites rather than the local friction. That is, when friction was low at one of the digit-object interfaces, only the applied normal forces increased at both digits. Thus sensory information related to the local frictional condition at the respective digit-object interfaces controlled the normal force at both digits. The normal:tangential force ratio at each digit appeared to be a controlled variable. It was adjusted independently at each digit to the minimum ratio required to prevent frictional slippage, keeping an adequate safety margin against slippage. This was accomplished by the scaling of

  15. Polarizable simulations with second order interaction model (POSSIM) force field: developing parameters for protein side-chain analogues.

    PubMed

    Li, Xinbi; Ponomarev, Sergei Y; Sa, Qina; Sigalovsky, Daniel L; Kaminski, George A

    2013-05-30

    A previously introduced polarizable simulations with second-order interaction model (POSSIM) force field has been extended to include parameters for small molecules serving as models for peptide and protein side-chains. Parameters have been fitted to permit reproducing many-body energies, gas-phase dimerization energies, and geometries and liquid-phase heats of vaporization and densities. Quantum mechanical and experimental data have been used as the target for the fitting. The POSSIM framework combines accuracy of a polarizable force field and computational efficiency of the second-order approximation of the full-scale induced point dipole polarization formalism. The resulting parameters can be used for simulations of the parameterized molecules themselves or their analogues. In addition to this, these force field parameters are currently being used in further development of the POSSIM fast polarizable force field for proteins.

  16. Polarizable Simulations with Second order Interaction Model (POSSIM) force field: Developing parameters for protein side-chain analogues

    PubMed Central

    Li, Xinbi; Ponomarev, Sergei Y.; Sa, Qina; Sigalovsky, Daniel L.; Kaminski, George A.

    2013-01-01

    A previously introduced POSSIM (POlarizable Simulations with Second order Interaction Model) force field has been extended to include parameters for small molecules serving as models for peptide and protein side-chains. Parameters have been fitted to permit reproducing many-body energies, gas-phase dimerization energies and geometries and liquid-phase heats of vaporization and densities. Quantum mechanical and experimental data have been used as the target for the fitting. The POSSIM framework combines accuracy of a polarizable force field and computational efficiency of the second-order approximation of the full-scale induced point dipole polarization formalism. The resulting parameters can be used for simulations of the parameterized molecules themselves or their analogues. In addition to this, these force field parameters are currently being employed in further development of the POSSIM fast polarizable force field for proteins. PMID:23420678

  17. 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...

  18. 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...

  19. 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...

  20. Evaluation of force-torque displays for use with space station telerobotic activities

    NASA Technical Reports Server (NTRS)

    Hendrich, Robert C.; Bierschwale, John M.; Manahan, Meera K.; Stuart, Mark A.; Legendre, A. Jay

    1992-01-01

    Recent experiments which addressed Space Station remote manipulation tasks found that tactile force feedback (reflecting forces and torques encountered at the end-effector through the manipulator hand controller) does not improve performance significantly. Subjective response from astronaut and non-astronaut test subjects indicated that force information, provided visually, could be useful. No research exists which specifically investigates methods of presenting force-torque information visually. This experiment was designed to evaluate seven different visual force-torque displays which were found in an informal telephone survey. The displays were prototyped in the HyperCard programming environment. In a within-subjects experiment, 14 subjects nullified forces and torques presented statically, using response buttons located at the bottom of the screen. Dependent measures included questionnaire data, errors, and response time. Subjective data generally demonstrate that subjects rated variations of pseudo-perspective displays consistently better than bar graph and digital displays. Subjects commented that the bar graph and digital displays could be used, but were not compatible with using hand controllers. Quantitative data show similar trends to the subjective data, except that the bar graph and digital displays both provided good performance, perhaps do to the mapping of response buttons to display elements. Results indicate that for this set of displays, the pseudo-perspective displays generally represent a more intuitive format for presenting force-torque information.