Science.gov

Sample records for active force development

  1. Air Force seal activities

    NASA Technical Reports Server (NTRS)

    Mayhew, Ellen R.

    1994-01-01

    Seal technology development is an important part of the Air Force's participation in the Integrated High Performance Turbine Engine Technology (IHPTET) initiative, the joint DOD, NASA, ARPA, and industry endeavor to double turbine engine capabilities by the turn of the century. Significant performance and efficiency improvements can be obtained through reducing internal flow system leakage, but seal environment requirements continue to become more extreme as the engine thermodynamic cycles advance towards these IHPTET goals. Brush seal technology continues to be pursued by the Air Force to reduce leakage at the required conditions. Likewise, challenges in engine mainshaft air/oil seals are also being addressed. Counter-rotating intershaft applications within the IHPTET initiative involve very high rubbing velocities. This viewgraph presentation briefly describes past and current seal research and development programs and gives a summary of seal applications in demonstrator and developmental engine testing.

  2. 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.

  3. 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.

  4. Differential effects of ballistic versus sensorimotor training on rate of force development and neural activation in humans.

    PubMed

    Gruber, Markus; Gruber, Stefanie B H; Taube, Wolfgang; Schubert, Martin; Beck, Sandra C; Gollhofer, Albert

    2007-02-01

    Balancing exercises on instable bases (sensorimotor training [SMT]) are often used in the rehabilitation process of an injured athlete to restore joint function. Recently it was shown that SMT was able to enhance rate of force development (RFD) in a maximal voluntary muscle contraction. The purpose of this study was to compare adaptations on strength capacity following ballistic strength training (BST) with those following an SMT during a training period of 1 microcycle (4 weeks). Maximum voluntary isometric strength (MVC), maximum RFD (RFDmax) and the corresponding neural activation of M. soleus (SOL), M. gastrocnemius (GAS), and M. tibialis anterior (TIB) were measured during plantar flexion in 33 healthy subjects. The subjects were randomly assigned to a SMT, BST, or control group. RFDmax increased significantly stronger following BST (48 +/- 16%; p < 0.01) compared to SMT (14 +/- 5%; p < 0.05), whereas MVC remained unchanged in both groups. Median frequencies of the electromyographic power spectrum during the first 200 ms of contraction for GAS increased following both BST (45 +/- 21%; p < 0.05) and SMT (45 +/- 22%; p < 0.05), but median frequencies for SOL increased only after SMT (13 +/- 4%; p < 0.05). Additionally, mean amplitude voltage increased following BST for SOL (38 +/- 12%; p < 0.01) and for GAS (73 +/- 23%; p < 0.01) during the first 100 ms, whereas it remained unchanged after SMT. It is concluded that BST and SMT may induce different neural adaptations that specifically affect recruitment and discharge rates of motor units at the beginning of voluntary contraction. Specific neural adaptations indicate that SMT might be used complementarily to BST, especially in sports that require contractile explosive properties in situations with high postural demands, e.g., during jumps in ball sports. PMID:17313292

  5. “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.

  6. 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.

  7. Active media under rotational forcing.

    PubMed

    Pérez-Villar, Vicente; Porteiro, Jose L F; Muñuzuri, Alberto P

    2006-10-01

    The bubble-free Belousov-Zhabotinsky reaction has been used to study the effects of centrifugal forces on autowave propagation. The reaction parameters were chosen such that the system oscillates naturally creating target waves. In the present study, the system was forced to rotate with a constant velocity around a central axis. In studying the effects of such a forcing on the system, we focused on target dynamics. The system reacts to this forcing in different ways, the most spectacular being a dramatic increase in the period of the target, the effect growing stronger as we move away from the center of rotation. A numerical study was carried out using the two-variable Oregonator model, modified to include convective effects through the diffusion coefficient. The numerical results showed a good qualitative agreement with those of the experiments. PMID:17155149

  8. Forcing FAK into Transcriptional Activity.

    PubMed

    Lietha, Daniel

    2016-08-01

    Focal adhesion kinase (FAK) has known signaling roles in cytoplasmic adhesion structures, but was recently shown to act as a transcriptional regulator in the nucleus. In this issue of Structure, Cardoso et al. (2016) report that mechanical forces translocate FAK to the nucleus of cardiomyocytes, and provide structural insights into how FAK interacts with the MEF2 transcription factor to control cardiac hypertrophy. PMID:27486913

  9. Development of a high force thermal latch

    NASA Astrophysics Data System (ADS)

    Nygren, William D.

    1995-05-01

    This paper describes the preliminary development of a high force thermal latch (HFTL). The HFTL has one moving part which is restrained in the latched position by a low melting temperature or fusible metal alloy. When heated the fusible alloy flows to a receiving chamber and in so doing at first releases the tension load in the latch bolt and later releases the bolt itself. The HFTL can be used in place of pyrotechnically activated spacecraft release devices in those instances where the elimination of both pyrotechnic shock-loading and rapid strain-energy release take precedence over the near instantaneous release offered by ordnance initiated devices.

  10. Development of a high force thermal latch

    NASA Technical Reports Server (NTRS)

    Nygren, William D.

    1995-01-01

    This paper describes the preliminary development of a high force thermal latch (HFTL). The HFTL has one moving part which is restrained in the latched position by a low melting temperature or fusible metal alloy. When heated the fusible alloy flows to a receiving chamber and in so doing at first releases the tension load in the latch bolt and later releases the bolt itself. The HFTL can be used in place of pyrotechnically activated spacecraft release devices in those instances where the elimination of both pyrotechnic shock-loading and rapid strain-energy release take precedence over the near instantaneous release offered by ordnance initiated devices.

  11. Influence of activity on plantar force distribution.

    PubMed

    Reinschmidt, C; Nigg, B M; Hamilton, G R

    1994-03-01

    The purpose of the study was to quantify the influence of physical activity on force distribution on the plantar surface of the foot. Eleven healthy subjects each performed 10 walking trials over a force distribution platform: five trials before and five trials after a 30-min run. For the analysis the foot was divided into three different regions (rearfoot, midfoot, forefoot), and maximal and average forces were determined for each region. The only statistically significant difference was found in the maximal force in the forefoot, but the difference was relatively small (<3%). The results suggested that the half-hour run did not have a large effect on the plantar force distribution. Differences between subjects were significant for all variables, indicating that relevant information on individual foot structure and/or gait may be obtained from the plantar force distribution. PMID:23916132

  12. Air Force Training for Instructional Systems Development.

    ERIC Educational Resources Information Center

    Calkins, Ronald R.

    Detailed information is provided about the Air Force Instructional System Development (ISD) Model to supplement the 1979 AECT presentation made in New Orleans. Information of interest to instructional systems designers includes (1) a short overview of the Air Force ISD model, (2) an extended example which demonstrates the Air Training Command…

  13. 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. PMID:26766518

  14. Development of a force measurement device

    NASA Astrophysics Data System (ADS)

    Wilmar, Otto

    1991-10-01

    The development of a Force Measurement Device (FMD) for recording interface forces between shaker table and Ariane 4 satellites is reported. The FMD is designed to measure forces and moments in the frequency range from 0.1 to 100 Hz with an accuracy better than 3 percent in basic modes up to 20 Hz, and 7 percent for higher modes. The ring shaped FMD concept contains 8 piezoelectronic force links and an analog electronic signal processing unit for reduction of the measured signals to 3 total forces and 3 moments. These are output to the test site signal analysis system. The required accuracy of the output and the structural safety of the device were verified by static tests.

  15. 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.

  16. 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.

  17. Active damping of modal vibrations by force apportioning

    NASA Technical Reports Server (NTRS)

    Hallauer, W. L., Jr.

    1980-01-01

    Force apportioning, a method of active structural damping based on that used in modal vibration testing of isolating modes by multiple shaker excitation, was analyzed and numerically simulated. A distribution of as few forces as possible on the structure is chosen so as to maximally affect selected vibration modes while minimally exciting all other modes. The accuracy of numerical simulations of active damping, active damping of higher-frequency modes, and studies of imperfection sensitivity are discussed. The computer programs developed are described and possible refinements of the research are examined.

  18. Air Force Research Laboratory Cryocooler Technology Development

    NASA Astrophysics Data System (ADS)

    Davis, Thomas M.; Smith, D. Adam; Easton, Ryan M.

    2004-06-01

    This paper presents an overview of the cryogenic refrigerator and cryogenic integration programs in development and characterization under the Cryogenic Cooling Technology Group, Space Vehicles Directorate of the Air Force Research Laboratory (AFRL). The vision statement for the group is to support the space community as the center of excellence for developing and transitioning space cryogenic thermal management technologies. This paper will describe the range of Stirling, pulse tube; reverse Brayton, and Joule-Thomson cycle cryocoolers currently under development to meet current and future Air Force and Department of Defense requirements. Cooling requirements at 10K, 35K, 60K, 95K, and multistage cooling requirements at 35/85K are addressed. In order to meet these various requirements, the Air Force Research Laboratory, Space Vehicles Directorate is pursuing various strategic cryocooler and cryogenic integration options. The Air Force Research Laboratory, working with industry partners, is also developing several advanced cryogenic integration technologies that will result in the reduction in current cryogenic system integration penalties and design time. These technologies include the continued development of gimbaled transport systems, 35K and 10K thermal storage units, heat pipes, cryogenic straps, and thermal switches.

  19. Force enhancement and force depression in a modified muscle model used for muscle activation prediction.

    PubMed

    Kosterina, Natalia; Wang, Ruoli; Eriksson, Anders; Gutierrez-Farewik, Elena M

    2013-08-01

    This article introduces history-dependent effects in a skeletal muscle model applied to dynamic simulations of musculoskeletal system motion. Force depression and force enhancement induced by active muscle shortening and lengthening, respectively, represent muscle history effects. A muscle model depending on the preceding contractile events together with the current parameters was developed for OpenSim software, and applied in simulations of standing heel-raise and squat movements. Muscle activations were computed using joint kinematics and ground reaction forces recorded from the motion capture of seven individuals. In the muscle-actuated simulations, a modification was applied to the computed activation, and was compared to the measured electromyography data. For the studied movements, the history gives a small but visible effect to the muscular force trace, but some parameter values must be identified before the exact magnitude can be analysed. The muscle model modification improves the existing muscle models and gives a more accurate description of underlying forces and activations in musculoskeletal system movement simulations. PMID:23561824

  20. MICROFLARE ACTIVITY DRIVEN BY FORCED MAGNETIC RECONNECTION

    SciTech Connect

    Jess, D. B.; Mathioudakis, M.; Crockett, P. J.; Keenan, F. P.; Browning, P. K.

    2010-03-20

    High cadence, multiwavelength, optical observations of a solar active region, obtained with the Swedish Solar Telescope, are presented. Two magnetic bright points are seen to separate in opposite directions at a constant velocity of 2.8 km s{sup -1}. After a separation distance of {approx}4400 km is reached, multiple Ellerman bombs are observed in both H{alpha} and Ca-K images. As a result of the Ellerman bombs, periodic velocity perturbations in the vicinity of the magnetic neutral line, derived from simultaneous Michelson Doppler Imager data, are generated with amplitude {+-}6 km s{sup -1} and wavelength {approx}1000 km. The velocity oscillations are followed by an impulsive brightening visible in H{alpha} and Ca-K, with a peak intensity enhancement of 63%. We interpret these velocity perturbations as the magnetic field deformation necessary to trigger forced reconnection. A time delay of {approx}3 minutes between the H{alpha}-wing and Ca-K observations indicates that the observed magnetic reconnection occurs at a height of {approx}200 km above the solar surface. These observations are consistent with theoretical predictions and provide the first observational evidence of microflare activity driven by forced magnetic reconnection.

  1. Connecting local active forces to macroscopic stress in elastic media.

    PubMed

    Ronceray, Pierre; Lenz, Martin

    2015-02-28

    In contrast with ordinary materials, living matter drives its own motion by generating active, out-of-equilibrium internal stresses. These stresses typically originate from localized active elements embedded in an elastic medium, such as molecular motors inside the cell or contractile cells in a tissue. While many large-scale phenomenological theories of such active media have been developed, a systematic understanding of the emergence of stress from the local force-generating elements is lacking. In this paper, we present a rigorous theoretical framework to study this relationship. We show that the medium's macroscopic active stress tensor is equal to the active elements' force dipole tensor per unit volume in both continuum and discrete linear homogeneous media of arbitrary geometries. This relationship is conserved on average in the presence of disorder, but can be violated in nonlinear elastic media. Such effects can lead to either a reinforcement or an attenuation of the active stresses, giving us a glimpse of the ways in which nature might harness microscopic forces to create active materials. PMID:25594831

  2. 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

  3. Rate of force development: physiological and methodological considerations.

    PubMed

    Maffiuletti, Nicola A; Aagaard, Per; Blazevich, Anthony J; Folland, Jonathan; Tillin, Neale; Duchateau, Jacques

    2016-06-01

    The evaluation of rate of force development during rapid contractions has recently become quite popular for characterising explosive strength of athletes, elderly individuals and patients. The main aims of this narrative review are to describe the neuromuscular determinants of rate of force development and to discuss various methodological considerations inherent to its evaluation for research and clinical purposes. Rate of force development (1) seems to be mainly determined by the capacity to produce maximal voluntary activation in the early phase of an explosive contraction (first 50-75 ms), particularly as a result of increased motor unit discharge rate; (2) can be improved by both explosive-type and heavy-resistance strength training in different subject populations, mainly through an improvement in rapid muscle activation; (3) is quite difficult to evaluate in a valid and reliable way. Therefore, we provide evidence-based practical recommendations for rational quantification of rate of force development in both laboratory and clinical settings. PMID:26941023

  4. Development of a tethered satellite force transducer

    NASA Astrophysics Data System (ADS)

    Rhew, Ray D.

    The SEDS (Small Expendable Deployer System)/Delta II is a demonstration flight of a tethered satellite deployer system. The satellite or end mass payload, which is deployed and tethered to the Delta II rocket, is instrumented to determine its dynamics during deployment. A three-component force transducer or strain-gage balance was developed to measure tether tension on the end-mass side of the tether. The transducer was designed to measure tensions up to 20N in each direction and resolve tensions as low as 0.002N. In addition, the transducer was required to withstand the shock, vibration, and temperature excursions of the mission. The development of the transducer from design to testing and integration is discussed.

  5. 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

  6. 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…

  7. 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.

  8. 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. PMID:27483519

  9. Protein kinase C enhances myosin light-chain kinase effects on force development and ATPase activity in rat single skinned cardiac cells.

    PubMed Central

    Clement, O; Puceat, M; Walsh, M P; Vassort, G

    1992-01-01

    Many neurohormones alter the force of cardiac contraction by variations in the intracellular Ca2+ concentration. alpha 1-Adrenergic and muscarinic stimulations, rather, modify the sensitivity of contractile proteins to Ca(2+)-calmodulin-myosin light-chain kinase (MLCK) complex induces a large increase in Ca2+ sensitivity (0.14 pCa unit) of these easily accessible myofilaments. This increase is further enhanced by up to 0.19 pCa unit when protein kinase C (PKC) is added together with MLCK. Similarly, the Ca2+ ATPase activity of skinned cells in suspension is increased in the presence of MLCK and further in the presence of both kinases. 32P-labelling and SDS/PAGE show that these changes are associated with light-chain 2 (LC2) phosphorylation together with phosphorylation of troponin I and troponin T when PKC is added. Although to a smaller extent than in smooth muscle, phosphorylation of cardiac myosin LC2 may be involved in the modulation of heart contractility. Images Fig. 4. Fig. 5. Fig. 6. PMID:1386218

  10. Blocked force measurement of an electro-active paper actuator using a cantilevered force transducer

    NASA Astrophysics Data System (ADS)

    Yun, Gyu-young; Kim, Heung Soo; Kim, Jaehwan

    2008-04-01

    The blocked force of an electro-active paper (EAPap) actuator was measured by a custom-built force transducer. The tip deflection of the force transducer was measured and converted into force using a simple Euler beam model. Since the blocked force is the maximum force generated at the tip of a bending actuator without displacement, the blocked force was found from the measured force of the transducer by extrapolating it. The force transducer was made from a thin steel cantilever beam and calibrated using a linear stage and a micro-balance. The measured maximum free bending displacement of the EAPap actuator was 4.4 mm and the blocked force was 224 µN under 350 V mm-1 AC electric field and 33 µN under DC electric field with the same field strength. When an AC electric field was applied to the actuator, the generated blocked force of the EAPap was about 700% larger than that caused by DC excitation. The proposed blocked force measurement is accurate down to a micro-Newton resolution under DC as well as AC electric fields.

  11. Defining Single Molecular Forces Required for Notch Activation Using Nano Yoyo.

    PubMed

    Chowdhury, Farhan; Li, Isaac T S; Ngo, Thuy T M; Leslie, Benjamin J; Kim, Byoung Choul; Sokoloski, Joshua E; Weiland, Elizabeth; Wang, Xuefeng; Chemla, Yann R; Lohman, Timothy M; Ha, Taekjip

    2016-06-01

    Notch signaling, involved in development and tissue homeostasis, is activated at the cell-cell interface through ligand-receptor interactions. Previous studies have implicated mechanical forces in the activation of Notch receptor upon binding to its ligand. Here we aimed to determine the single molecular force required for Notch activation by developing a novel low tension gauge tether (LTGT). LTGT utilizes the low unbinding force between single-stranded DNA (ssDNA) and Escherichia coli ssDNA binding protein (SSB) (∼4 pN dissociation force at 500 nm/s pulling rate). The ssDNA wraps around SSB and, upon application of force, unspools from SSB, much like the unspooling of a yoyo. One end of this nano yoyo is attached to the surface though SSB, while the other end presents a ligand. A Notch receptor, upon binding to its ligand, is believed to undergo force-induced conformational changes required for activating downstream signaling. If the required force for such activation is larger than 4 pN, ssDNA will unspool from SSB, and downstream signaling will not be activated. Using these LTGTs, in combination with the previously reported TGTs that rupture double-stranded DNA at defined forces, we demonstrate that Notch activation requires forces between 4 and 12 pN, assuming an in vivo loading rate of 60 pN/s. Taken together, our study provides a direct link between single-molecular forces and Notch activation. PMID:27167603

  12. Protrusion force microscopy reveals oscillatory force generation and mechanosensing activity of human macrophage podosomes.

    PubMed

    Labernadie, Anna; Bouissou, Anaïs; Delobelle, Patrick; Balor, Stéphanie; Voituriez, Raphael; Proag, Amsha; Fourquaux, Isabelle; Thibault, Christophe; Vieu, Christophe; Poincloux, Renaud; Charrière, Guillaume M; Maridonneau-Parini, Isabelle

    2014-01-01

    Podosomes are adhesion structures formed in monocyte-derived cells. They are F-actin-rich columns perpendicular to the substrate surrounded by a ring of integrins. Here, to measure podosome protrusive forces, we designed an innovative experimental setup named protrusion force microscopy (PFM), which consists in measuring by atomic force microscopy the deformation induced by living cells onto a compliant Formvar sheet. By quantifying the heights of protrusions made by podosomes onto Formvar sheets, we estimate that a single podosome generates a protrusion force that increases with the stiffness of the substratum, which is a hallmark of mechanosensing activity. We show that the protrusive force generated at podosomes oscillates with a constant period and requires combined actomyosin contraction and actin polymerization. Finally, we elaborate a model to explain the mechanical and oscillatory activities of podosomes. Thus, PFM shows that podosomes are mechanosensing cell structures exerting a protrusive force. PMID:25385672

  13. Protrusion force microscopy reveals oscillatory force generation and mechanosensing activity of human macrophage podosomes

    NASA Astrophysics Data System (ADS)

    Labernadie, Anna; Bouissou, Anaïs; Delobelle, Patrick; Balor, Stéphanie; Voituriez, Raphael; Proag, Amsha; Fourquaux, Isabelle; Thibault, Christophe; Vieu, Christophe; Poincloux, Renaud; Charrière, Guillaume M.; Maridonneau-Parini, Isabelle

    2014-11-01

    Podosomes are adhesion structures formed in monocyte-derived cells. They are F-actin-rich columns perpendicular to the substrate surrounded by a ring of integrins. Here, to measure podosome protrusive forces, we designed an innovative experimental setup named protrusion force microscopy (PFM), which consists in measuring by atomic force microscopy the deformation induced by living cells onto a compliant Formvar sheet. By quantifying the heights of protrusions made by podosomes onto Formvar sheets, we estimate that a single podosome generates a protrusion force that increases with the stiffness of the substratum, which is a hallmark of mechanosensing activity. We show that the protrusive force generated at podosomes oscillates with a constant period and requires combined actomyosin contraction and actin polymerization. Finally, we elaborate a model to explain the mechanical and oscillatory activities of podosomes. Thus, PFM shows that podosomes are mechanosensing cell structures exerting a protrusive force.

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

    PubMed

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

    2016-09-10

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

  15. 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. PMID:15794037

  16. The Distribution of Active Force Generators Controls Mitotic Spindle Position

    NASA Astrophysics Data System (ADS)

    Grill, Stephan W.; Howard, Jonathon; Schäffer, Erik; Stelzer, Ernst H. K.; Hyman, Anthony A.

    2003-07-01

    During unequal cell divisions a mitotic spindle is eccentrically positioned before cell cleavage. To determine the basis of the net force imbalance that causes spindle displacement in one-cell Caenorhabditis elegans embryos, we fragmented centrosomes with an ultraviolet laser. Analysis of the mean and variance of fragment speeds suggests that the force imbalance is due to a larger number of force generators pulling on astral microtubules of the posterior aster relative to the anterior aster. Moreover, activation of heterotrimeric guanine nucleotide-binding protein (G protein) α subunits is required to generate these astral forces.

  17. 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.

  18. Forcing it on: Cytoskeletal dynamics during lymphocyte activation

    NASA Astrophysics Data System (ADS)

    Upadhyaya, Arpita

    2012-02-01

    Formation of the immune synapse during lymphocyte activation involves cell spreading driven by large scale physical rearrangements of the actin cytoskeleton and the cell membrane. Several recent observations suggest that mechanical forces are important for efficient T cell activation. How forces arise from the dynamics of the cytoskeleton and the membrane during contact formation, and their effect on signaling activation is not well understood. We have imaged membrane topography, actin dynamics and the spatiotemporal localization of signaling clusters during the very early stages of spreading. Formation of signaling clusters was closely correlated with the movement and topography of the membrane in contact with the activating surface. Further, we observed membrane waves driven by actin polymerization originating at these signaling clusters. Actin-driven membrane protrusions likely play an important role in force generation at the immune synapse. In order to study cytoskeletal forces during T-cell activation, we studied cell spreading on elastic gels. We found that gel stiffness influences cell morphology, actin dynamics and receptor activation. Efforts to determine the quantitative relationships between cellular forces and signaling are underway. Our results suggest a role for cytoskeleton driven forces during signaling activation in lymphocytes.

  19. Developing pressures: fluid forces driving morphogenesis.

    PubMed

    Navis, Adam; Bagnat, Michel

    2015-06-01

    Over several decades genetic studies have unraveled many molecular mechanisms that underlie the signaling networks guiding morphogenesis, but the mechanical forces at work remain much less well understood. Accumulation of fluid within a luminal space can generate outward hydrostatic pressure capable of shaping morphogenesis at several scales, ranging from individual organs to the entire vertebrate body-plan. Here, we focus on recent work that uncovered mechanical roles for fluid secretion during morphogenesis. Identifying the roles and regulation of fluid secretion will be instrumental for understanding the mechanics of morphogenesis as well as many human diseases of complex genetic and environmental origin including secretory diarrheas and scoliosis. PMID:25698116

  20. 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.

  1. 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…

  2. Post-activation Potentiation in Propulsive Force after Specific Swimming Strength Training.

    PubMed

    Barbosa, A C; Barroso, R; Andries, O

    2016-04-01

    We investigated whether a conditioning activity (8×12.5 m with 2.5 min-interval using both hand paddles and parachute) induced post-activation potentiation in swimming propulsive force and whether a swimmer's force level affected a post-activation potentiation response. 8 competitive swimmers (5 males and 3 females, age: 18.4±1.3 years; IPS=796±56) performed a 10 s maximum tethered swimming test 8 and 4 min before (the highest value was considered as PRE), and 2.5 and 6.5 min after (POST1 and POST2, respectively) the conditioning activity. Rate of force development was not affected, but peak force in POST1 (p=0.02) and impulse in both POST1 (p=0.007) and POST2 (p=0.004) were reduced. Possibly the conditioning activity induced greater fatigue than post-activation potentiation benefits. For instance, the number of repetitions might have been excessive, and rest intervals between the conditioning activity and POST1 and POST2 were possibly too short. There were positive correlations between PRE peak force and changes in peak force and rate of force development. Although conditioning activity was detrimental, positive correlations suggest that weaker swimmers experience a deterioration of performance more than the stronger ones. This conditioning activity is not recommended for swimmers with the current competitive level before a competitive event. PMID:26667922

  3. 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. PMID:26257071

  4. Research and Development of Small Force Standards at NIM

    NASA Astrophysics Data System (ADS)

    Hu, Gang; Song, Le; Meng, Feng; Zhang, Wei; Zhang, Zhimin; Zhang, Yue; Zheng, Yelong

    With the development and industrialization of micro- and nano- technology, small force measurements are widely applied in many fields such as advanced materials, bio-technology, aerospace and so on. For realizing traceable small forces and founding small force metrology hierarchy in China, NIM has launched a research project on small force metrology in 2011. 2 methods for small force realization at the scale of nano-Newton to micro-Newton are applied: electrical force based method and mass based method. The initial prototype of small force standard, which is based on the electrostatic force realization and adopts a coaxial cylindrical capacitor, has been developed and experimented. 2 kinds of micro force transmission mechanism are applied to the prototype: a parallelogram mechanism with 4 flexure hinges, and a lever-type force measurement system based on an elastic torsion bar. The structure and key units of 2 schemes are described in detail, the experiment results are demonstrated. The system stiffness of torsion bar scheme is smaller than that of flexure hinges scheme. In addition, structure of the initial prototype will be improved, and the environment conditions will be controlled strictly in our further experiments to minimize the creep of our system.

  5. Changes in Tibiofemoral Forces due to Variations in Muscle Activity during Walking

    PubMed Central

    DeMers, Matthew S.; Pal, Saikat; Delp, Scott L.

    2015-01-01

    Muscles induce large forces in the tibiofemoral joint during walking and thereby influence the health of tissues like articular cartilage and menisci. It is possible to walk with a wide variety of muscle coordination patterns, but the effect of varied muscle coordination on tibiofemoral contact forces remains unclear. The goal of this study was to determine the effect of varied muscle coordination on tibiofemoral contact forces. We developed a musculoskeletal model of a subject walking with an instrumented knee implant. Using an optimization framework, we calculated the tibiofemoral forces resulting from muscle coordination that reproduced the subject’s walking dynamics. We performed a large set of optimizations in which we systematically varied the coordination of muscles to determine the influence on tibiofemoral force. Model-predicted tibiofemoral forces arising with minimum muscle activation matched in vivo forces measured during early stance, but were greater than in vivo forces during late stance. Peak tibiofemoral forces during late stance could be reduced by increasing the activation of the gluteus medius, uniarticular hip flexors, and soleus, and by decreasing the activation of the gastrocnemius and rectus femoris. These results suggest that retraining of muscle coordination could substantially reduce tibiofemoral forces during late stance. PMID:24615885

  6. 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

  7. 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)

  8. 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.

  9. Directory of Development Activities.

    ERIC Educational Resources Information Center

    Control Data Corp., Minneapolis, Minn.

    Assembled in a loose leaf notebook, this collection of independent on-the-job activities is designed to facilitate employee development and intended to help improve an organization's performance appraisal system. The on-the-job development activities described derive from job descriptions, performance appraisal forms, and discussions with job…

  10. Evolutionary and Environmental Forces Sculpting Leaf Development.

    PubMed

    Chitwood, Daniel H; Sinha, Neelima R

    2016-04-01

    Leaf shape is spectacularly diverse. As a major component of plant architecture and an interface for light capture, gas exchange, and thermoregulation, the potential contributions of leaves to plant fitness are innumerable. Particularly because of their intimate association and interaction with the surrounding environment, both the plasticity of leaf shape during the lifetime of a plant and the evolution of leaf shape over geologic time are revealing with respect to leaf function. Leaf shapes arise within a developmental context that constrains both their evolution and environmental plasticity. Quantitative models capturing genetic diversity, developmental context, and environmental plasticity will be required to fully understand the evolution and development of leaf shape and its response to environmental pressures. In this review, we discuss recent literature demonstrating that distinct molecular pathways are modulated by specific environmental inputs, the output of which regulates leaf dissection. We propose a synthesis explaining both historical patterns in the paleorecord and conserved plastic responses in extant plants. Understanding the potential adaptive value of leaf shape, and how to molecularly manipulate it, will prove to be invaluable in designing crops optimized for future climates. PMID:27046820

  11. Interaction forces between waterborne bacteria and activated carbon particles.

    PubMed

    Busscher, Henk J; Dijkstra, Rene J B; Langworthy, Don E; Collias, Dimitris I; Bjorkquist, David W; Mitchell, Michael D; Van der Mei, Henny C

    2008-06-01

    Activated carbons remove waterborne bacteria from potable water systems through attractive Lifshitz-van der Waals forces despite electrostatic repulsion between negatively charged cells and carbon surfaces. In this paper we quantify the interaction forces between bacteria with negatively and positively charged, mesoporous wood-based carbons, as well as with a microporous coconut carbon. To this end, we glued carbon particles to the cantilever of an atomic force microscope and measured the interaction forces upon approach and retraction of thus made tips. Waterborne Raoultella terrigena and Escherichia coli adhered weakly (1-2 nN) to different activated carbon particles, and the main difference between the activated carbons was the percentage of curves with attractive sites revealed upon traversing of a carbon particle through the bacterial EPS layer. The percentage of curves showing adhesion forces upon retraction varied between 21% and 69%, and was highest for R. terrigena with positively charged carbon (66%) and a coconut carbon (69%). Macroscopic bacterial removal by the mesoporous carbon particles increased with increasing percentages of attractive sites revealed upon traversing a carbon particle through the outer bacterial surface layer. PMID:18405910

  12. Spatiotemporal tuning of brain activity and force performance

    PubMed Central

    Coombes, Stephen A.; Corcos, Daniel M.; Vaillancourt, David E.

    2010-01-01

    The spatial and temporal features of visual stimuli are either processed independently or are conflated in specific cells of visual cortex. Although spatial and temporal features of visual stimuli influence motor performance, it remains unclear how spatiotemporal information is processed beyond visual cortex in brain regions that control movement. We used functional magnetic resonance imaging to examine how brain activity and force control are influenced by visual gain at a high visual feedback frequency of 6.4 Hz and a low visual feedback frequency of 0.4 Hz. At 6.4 Hz, increasing visual gain led to improved force performance and increased activity in classic areas of the visuomotor system – V5, IPL, SPL, PMv, SMA-proper, and M1. At 0.4 Hz, increasing gain also lead to improved force performance. In addition to activation in M1/PMd and IPL in the visuomotor system, increasing visual gain at 0.4 Hz also corresponded with activity in the striatal-frontal circuit including DLPFC, ACC, and widespread activity in putamen, caudate, and SMA-proper. This study demonstrates that the frequency of visual feedback drives where in the brain visual gain mediated reductions in force error are regulated. PMID:20937396

  13. Shoulder model validation and joint contact forces during wheelchair activities

    PubMed Central

    Morrow, Melissa M.B.; Kaufman, Kenton R.; An, Kai-Nan

    2010-01-01

    Chronic shoulder impingement is a common problem for manual wheelchair users. The loading associated with performing manual wheelchair activities of daily living is substantial and often at a high frequency. Musculoskeletal modeling and optimization techniques can be used to estimate the joint contact forces occurring at the shoulder to assess the soft tissue loading during an activity and to possibly identify activities and strategies that place manual wheelchair users at risk for shoulder injuries. The purpose of this study was to validate an upper extremity musculoskeletal model and apply the model to wheelchair activities for analysis of the estimated joint contact forces. Upper extremity kinematics and handrim wheelchair kinetics were measured over three conditions: level propulsion, ramp propulsion, and a weight relief lift. The experimental data were used as input to a subject-specific musculoskeletal model utilizing optimization to predict joint contact forces of the shoulder during all conditions. The model was validated using a mean absolute error calculation. Model results confirmed that ramp propulsion and weight relief lifts place the shoulder under significantly higher joint contact loading than level propulsion. In addition, they exhibit large superior contact forces that could contribute to impingement. This study highlights the potential impingement risk associated with both the ramp and weight relief lift activities. Level propulsion was shown to have a low relative risk of causing injury, but with consideration of the frequency with which propulsion is performed, this observation is not conclusive. PMID:20840833

  14. 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.

  15. Short-term effects of integrated motor imagery practice on muscle activation and force performance.

    PubMed

    Di Rienzo, F; Blache, Y; Kanthack, T F D; Monteil, K; Collet, C; Guillot, A

    2015-10-01

    The effect of motor imagery (MI) practice on isometric force development is well-documented. However, whether practicing MI during rest periods of physical training improves the forthcoming performance remains unexplored. We involved 18 athletes in a counterbalanced design including three physical training sessions scheduled over five consecutive days. Training involved 10 maximal isometric contractions against a force plate, with the elbow at 90°. During two sessions, we integrated MI practice (focusing on either muscle activation or relaxation) during the inter-trial rest periods. We measured muscle performance from force plate and electromyograms of the biceps brachii and anterior deltoideus. We continuously monitored electrodermal activity (EDA) to control sympathetic nervous system activity. MI of muscle activation resulted in higher isometric force as compared to both MI of muscle relaxation and passive recovery (respectively +2.1% and +3.5%). MI practice of muscle relaxation also outperformed the control condition (+1.9%). Increased activation of the biceps brachii was recorded under both MI practice conditions compared to control. Biceps brachii activation was similar between the two MI practice conditions, but electromyography revealed a marginal trend toward greater activation of the anterior deltoideus during MI practice of muscle activation. EDA and self-reports indicated that these effects were independent from physiological arousal and motivation. These results might account for priming effects of MI practice yielding to higher muscle activation and force performance. Present findings may be of interest for applications in sports training and neurologic rehabilitation. PMID:26241339

  16. 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…

  17. Force Spectroscopy of Substrate Molecules En Route to the Proteasome's Active Sites

    PubMed Central

    Classen, Mirjam; Breuer, Sarah; Baumeister, Wolfgang; Guckenberger, Reinhard; Witt, Susanne

    2011-01-01

    We used an atomic force microscope to study the mechanism underlying the translocation of substrate molecules inside the proteasome. Our specific experimental setup allowed us to measure interaction forces between the 20S proteasome and its substrates. The substrate (β-casein) was covalently bound either via a thiol-Au bond or by a PEG-based binding procedure to the atomic force microscope cantilever tip and offered as bait to proteasomes from Methanosarcina mazei. The proteasomes were immobilized densely in an upright orientation on mica, which made their upper pores accessible for substrates to enter. Besides performing conventional single-molecule force spectroscopy experiments, we developed a three-step procedure that allows the detection of specific proteasome-substrate single-molecule events without tip-sample contact. Using the active 20S wild type and an inactive active-site mutant, as well as two casein mutants bound with opposite termini to the microscope tip, we detected no directional preference of the proteasome-substrate interactions. By comparing the distribution of the measured forces for the proteasome-substrate interactions, were observed that a significant proportion of interaction events occurred at higher forces for the active versus the inactive proteasome. These forces can be attributed to the translocation of substrate en route to the active sites that are harbored deep inside the proteasome. PMID:21244845

  18. Elbow and wrist joint contact forces during occupational pick and place activities.

    PubMed

    Chadwick, E K; Nicol, A C

    2000-05-01

    A three-dimensional, mathematical model of the elbow and wrist joints, including 15 muscle units, 3 ligaments and 4 joint forces, has been developed. A new strain gauge transducer has been developed to measure functional grip forces. The device measures radial forces divided into six components and forces of up to 250N per segment can be measured with an accuracy of +/-1%. Ten normal volunteers were asked to complete four tasks representing occupational activities, during which time their grip force was monitored. Together with kinematic information from the six-camera Vicon data, the moment effect of these loads at the joints was calculated. These external moments are assumed to be balanced by the internal moments, generated by the muscles, passive soft tissue and bone contact. The effectiveness of the body's internal structures in generating joint moments was assessed by studying the geometry of a simplified model of the structures, where information about the lines of action and moment arms of muscles, tendons and ligaments is contained. The assumption of equilibrium between these external and internal joint moments allows formulation of a set of equations from which muscle and joint forces can be calculated. A two stage, linear optimisation routine minimising the overall muscle stress and the sum of the joint forces has been used to overcome the force-sharing problem. Humero-ulnar forces of up to 1600N, humero-radial forces of up to 800N and wrist joint forces of up to 2800N were found for moderate level activity. The model was validated by comparison with other studies. PMID:10708780

  19. Active Control of Transition Using the Lorentz Force

    NASA Technical Reports Server (NTRS)

    Nosenchuck, Daniel; Brown, Garry

    2007-01-01

    A new concept and technique has been developed to directly control boundary-layer transition and turbulence. Near-wall vertical motions are directly suppressed through the application of Lorentz force. Current (j) and magnetic (b) fields are applied parallel to the boundary and normal to each other to produce a Lorentz force (j x B) normal to the boundary. This approach is called magnetic turbulence control (MTC). Experiments have been performed on flat-plate transitional and turbulent boundary layers in water seeded with a weak electrolyte.

  20. Scrambled eggs: mechanical forces as ecological factors in early development.

    PubMed

    Moore, Steven W

    2003-01-01

    Many ecological interactions involve, at some level, mechanical forces and the movements or structural deformations they produce. Although the most familiar examples involve the functional morphology of adult structures, all life history stages (not just the adults) are subject to the laws of physics. Moreover, the success of every lineage depends on the success of every life history stage (again, not just the adults). Therefore, insights gained by using mechanical engineering principles and techniques to study ecological interactions between gametes, embryos, larvae, and their environment are essential to a well-rounded understanding of development, ecology, and evolution. Here I draw on examples from the literature and my own research to illustrate ways in which mechanical forces in the environment shape development. These include mechanical forces acting as selective factors (e.g., when coral gamete size and shape interact with turbulent water flow to determine fertilization success) and as developmental cues (e.g., when plant growth responds to gravity or bone growth responds to mechanical loading). I also examine the opposite cause-and-effect relationship by considering examples in which the development of organisms impacts ecologically relevant mechanical forces. Finally, I discuss the potential for ecological pattern formation as a result of feedback loops created by such bidirectional interactions between developmental processes and mechanical forces in the environment. PMID:12492411

  1. Development of force-feedback-controlled Nafion micromanipulators

    NASA Astrophysics Data System (ADS)

    Zhou, Wenli; Li, Wen J.; Xi, Ning; Ma, Shugen

    2001-07-01

    The ability to manipulation of biological cells while having reflective-force information from the cells is a key technology necessary for many new applications in Bio-MEMS, but is currently lacking in all cellular manipulators. We will report on our preliminary experimental work in using an Ionic Conducting Polymer Film (ICPF) to develop a biological cell robotic gripper with force sensing capability. ICPF actuators are able to give large deflection with small input voltage (~5V), and also able to give relatively large output voltage due to deflection by a mechanical forces, thus are investigated as a possible material to make force-feedback controlled cellular manipulators in our work. A laser micromachining process is introduced to fabricate arrays of ICPF griping devices, which can be potentially integrated onto a substrate to develop a micro manipulation system. Individual multi-finger grippers with dimensions of 200micrometers x 200micrometers x 3000micrometers for each finger were realized. We will report on the design, fabrication procedures, and operating performance of these micro-grippers. Further development in the reduction of size of these actuators will enable effective force-feedback control of underwater micro objects and lead to new frontiers in cellular manipulation.

  2. IAU Office of Astronomy for Development: Task Force Children and School Education

    NASA Astrophysics Data System (ADS)

    Russo, Pedro; Gomez, Edward

    2015-03-01

    The main mission of the IAU OAD Task Force on Children and School Education is to support the implementation of the pre-tertiary education part of the IAU Strategic Plan `Astronomy for Development'. In this presentation we will give an overview of the role and programme of the task force as well as a general discussion about the past, present and future IAU education activities and programmes.

  3. Force field development from first principles for materials design

    NASA Astrophysics Data System (ADS)

    Chan, Maria; Kinaci, Alper; Narayanan, Badri; Sen, Fatih; Gray, Stephen; Davis, Michael; Sankaranaryanan, Subramanian

    2015-03-01

    The ability to perform accurate calculations efficiently is crucial for computational materials design. In this talk, we will discuss a stream-lined approach to force field development using first principles density functional theory training data and machine learning algorithms. We will also discuss the validation of this approach on precious metal nanoparticles.

  4. 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,…

  5. 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…

  6. 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…

  7. 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…

  8. Radial force development during root growth measured by photoelasticity

    NASA Astrophysics Data System (ADS)

    Kolb, Evelyne; Hartmann, Christian; Genet, Patricia

    2012-02-01

    The mechanical and topological properties of a soil like the global porosity and the distribution of void sizes greatly affect the development of a plant root, which in turn affects the shoot development. In particular, plant roots growing in heterogeneous medium like sandy soils or cracked substrates have to adapt their morphology and exert radial forces depending on the pore size in which they penetrate. We propose a model experiment in which a pivot root (chick-pea seeds) of millimetric diameter has to grow in a size-controlled gap δ (δ ranging 0.5-2.3 mm) between two photoelastic grains. By time-lapse imaging, we continuously monitored the root growth and the development of optical fringes in the photoelastic neighbouring grains when the root enters the gap. Thus we measured simultaneously and in situ the root morphological changes (length and diameter growth rates, circumnutation) as well as the radial forces the root exerts. Radial forces were increasing in relation with gap constriction and experiment duration but a levelling of the force was not observed, even after 5 days and for narrow gaps. The inferred mechanical stress was consistent with the turgor pressure of compressed cells. Therefore our set-up could be a basis for testing mechanical models of cellular growth.

  9. [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. PMID:25051791

  10. An all-atom force field developed for Zn₄O(RCO₂)₆ metal organic frameworks.

    PubMed

    Sun, Yingxin; Sun, Huai

    2014-03-01

    An all-atom force field is developed for metal organic frameworks Zn₄O(RCO₂)₆ by fitting to quantum mechanics data. Molecular simulations are conducted to validate the force field by calculating thermal expansion coefficients, crystal bulk and Young's moduli, power spectra, self-diffusion coefficients, and activation energies of self-diffusions for benzene and n-hexane. The calculated results are in good agreement with available experimental data. The proposed force field is suitable for simulations of adsorption or diffusion of organic molecules with flexible frameworks. PMID:24562858

  11. 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…

  12. In vivo tendon forces correlate with activity level and remain bounded: evidence in a rabbit flexor tendon model.

    PubMed

    Malaviya, P; Butler, D L; Korvick, D L; Proch, F S

    1998-11-01

    While some tendons and ligaments in the lower extremity develop peak forces proportional to the intensity of activity (Komi 1990; Komi et al., 1992; Korvick et al., 1996), others maintain a steady force regardless of activity level (Herzog et al., 1993; Prilutsky et al., 1994). Investigators (Biewener et al., 1988; Korvick et al., 1996) have also shown that peak knee and ankle tendon forces approach one-quarter to one-third of ultimate or failure force values. In the rabbit flexor digitorum profundus (FDP) tendon model we tested several hypotheses, chiefly that peak in vivo forces not only increase with increasing activity but do not exceed one-third of their ultimate or failure values. The FDP tendon was instrumented in three animals, and each rabbit subjected to an experimental design involving three activity levels. Peak tensile forces and rates of rise and fall in tendon force increased significantly with increasing activity (p < 0.01). Further, the tendon maintained a non-zero force level throughout all trials. For the most vigorous activity, inclined hopping, tensile forces and stresses were, on average, within 30% of the tendon's ultimate force and stress values, respectively. Such in vivo measurements in different tendon systems should help investigators better understand the recruitment and contribution of important muscle-tendon units to joint stability and gait. PMID:9880061

  13. Propulsion Aeroelastic Analysis Developed for Flutter and Forced Response

    NASA Technical Reports Server (NTRS)

    Bakhle, Milind A.

    2000-01-01

    The NASA Glenn Research Center at Lewis Field develops new technologies to increase the fuel efficiency of aircraft engines, improve the safety of engine operation, reduce emissions, and reduce engine noise. With the development of new designs for fans, compressors, and turbines to achieve these goals, the basic aeroelastic requirements are that there should be no flutter (self-excited vibrations) or high resonant blade stresses (due to forced response) in the operating regime. Therefore, an accurate prediction and analysis capability is required to verify the aeroelastic soundness of the designs. Such a three-dimensional viscous propulsion aeroelastic analysis capability has been developed at Glenn with support from the Advanced Subsonic Technology (AST) program. This newly developed aeroelastic analysis capability is based on TURBO, a threedimensional unsteady aerodynamic Reynolds-averaged Navier-Stokes turbomachinery code developed previously under a grant from Glenn. TURBO can model the viscous flow effects that play an important role in certain aeroelastic problems such as flutter with flow separation, flutter at high loading conditions near the stall line (stall flutter), flutter in the presence of shock and boundary-layer interaction, and forced response due to wakes and shock impingement. In aeroelastic analysis, the structural dynamics representation of the blades is based on normal modes. A finite-element analysis code is used to calculate these in-vacuum vibration modes and the associated natural frequencies. In an aeroelastic analysis using the TURBO code, flutter and forced response are modeled as being uncoupled. To calculate if a blade row will flutter, one prescribes the motion of the blade to be a harmonic vibration in a specified in-vacuum normal mode. An aeroelastic analysis preprocessor is used to generate the displacement field required for the analysis. The work done by aerodynamic forces on the vibrating blade during a cycle of vibration is

  14. Modulation of post-movement beta rebound by contraction force and rate of force development.

    PubMed

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

    2016-07-01

    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 Wiley Periodicals, Inc. PMID:27061243

  15. 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

  16. Labor force activities and income among young Guatemalan adults.

    PubMed

    Hoddinott, John; Behrman, Jere R; Martorell, Reynaldo

    2005-06-01

    This paper considers labor force activities among adults (26 to 41 years of age in 2003) who participated as children in a nutrition supplementation trial in Guatemala. The vast majority of men are engaged in some type of income-generating activity in 2002-04. However, unlike their fathers, these men are much more likely to be engaged in wage labor, even if they remain in the original study villages. Those engaged in wage employment appear to do so steadily. Women are much more likely to be engaged in some type of income-generating activity than their mothers. For both men and women, there appears to be considerable movement in and out of own business activities. In Guatemala City, wage work is the predominant economic activity with more than half of the women interviewed working for wages; elsewhere operating non-farm businesses is the most often cited activity. For both men and women, agriculture now appears to be very much a secondary activity. PMID:16060216

  17. Development of a high pressure micromechanical force apparatus

    NASA Astrophysics Data System (ADS)

    Lee, Bo Ram; Koh, Carolyn A.; Sum, Amadeu K.

    2014-09-01

    The formation of gas hydrates and subsequent plugging of pipelines are risks that need to be well understood during the production and transportation of oil and gas in subsea flowlines. These flowlines are typically operating at low temperature and high pressure conditions, which are well within the hydrate formation stability region. One of the key processes for hydrate plugs to develop is the agglomeration of hydrates. To obtain a more comprehensive understanding on this problem, we have developed a high-pressure micromechanical force (MMF) apparatus to directly measure cohesive forces between gas hydrate particles. The MMF system is housed in a stainless steel vessel that can withstand pressures of up to 10 MPa, thereby facilitating studies on a broad spectrum of hydrate formers and conditions. The MMF apparatus comprises of two cantilever fibers: one is stationary and another is manipulated via a nano-manipulator. Water droplets (˜500 μm in diameter) are placed at the end of the each cantilever fiber so that they can be converted to hydrate. In order to demonstrate the stability of this apparatus, CH4/C2H6 (74.7 mol. %/25.3 mol. %) mixed hydrates were prepared at 2 MPa and -5 °C and annealed at 0 °C for 15 h. Subsequently, the hydrate particle cohesive force was measured at 2 °C. Compared with the cohesive force of cyclopentane hydrates in cyclopentane liquid (˜4.3 mN/m), the average cohesive force of gas hydrates was about 10 times higher, ˜43 mN/m. Studies using this new high pressure MMF apparatus will be central to better understand the agglomeration of hydrates in multiphase flowlines.

  18. Development of software for human muscle force estimation.

    PubMed

    Tang, Gang; Qian, Li-wei; Wei, Gao-feng; Wang, Hong-sheng; Wang, Cheng-tao

    2012-01-01

    Muscle force estimation (MFE) has become more and more important in exploring principles of pathological movement, studying functions of artificial muscles, making surgery plan for artificial joint replacement, improving the biomechanical effects of treatments and so on. At present, existing software are complex for professionals, so we have developed a new software named as concise MFE (CMFE). CMFE which provides us a platform to analyse muscle force in various actions includes two MFE methods (static optimisation method and electromyographic-based method). Common features between these two methods have been found and used to improve CMFE. A case studying the major muscles of lower limb of a healthy subject walking at normal speed has been presented. The results are well explained from the effect of the motion produced by muscles during movement. The development of this software can improve the accuracy of the motion simulations and can provide a more extensive and deeper insight in to muscle study. PMID:21607886

  19. Sustained α-catenin Activation at E-cadherin Junctions in the Absence of Mechanical Force.

    PubMed

    Biswas, Kabir H; Hartman, Kevin L; Zaidel-Bar, Ronen; Groves, Jay T

    2016-09-01

    Mechanotransduction at E-cadherin junctions has been postulated to be mediated in part by a force-dependent conformational activation of α-catenin. Activation of α-catenin allows it to interact with vinculin in addition to F-actin, resulting in a strengthening of junctions. Here, using E-cadherin adhesions reconstituted on synthetic, nanopatterned membranes, we show that activation of α-catenin is dependent on E-cadherin clustering, and is sustained in the absence of mechanical force or association with F-actin or vinculin. Adhesions were formed by filopodia-mediated nucleation and micron-scale assembly of E-cadherin clusters, which could be distinguished as either peripheral or central assemblies depending on their relative location at the cell-bilayer adhesion. Whereas F-actin, vinculin, and phosphorylated myosin light chain associated only with the peripheral assemblies, activated α-catenin was present in both peripheral and central assemblies, and persisted in the central assemblies in the absence of actomyosin tension. Impeding filopodia-mediated nucleation and micron-scale assembly of E-cadherin adhesion complexes by confining the movement of bilayer-bound E-cadherin on nanopatterned substrates reduced the levels of activated α-catenin. Taken together, these results indicate that although the initial activation of α-catenin requires micron-scale clustering that may allow the development of mechanical forces, sustained force is not required for maintaining α-catenin in the active state. PMID:27602732

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

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 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...

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

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 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...

  3. 16 CFR 1211.13 - Inherent force activated secondary door sensors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 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...

  4. Development and Application of a Multi-Axis Dynamometer for Measuring Grip Force

    PubMed Central

    Irwin, C.B.; Towles, J.D; Radwin, R.G.

    2013-01-01

    Objective This article describes the development and application of a novel multi-axis hand dynamometer for quantifying two-dimensional grip force magnitude and direction in the flexion-extension plane of the fingers. Methods A three-beam reconfigurable form dynamometer, containing two active beams for measuring orthogonal forces and moments regardless of point of force application, was designed, fabricated and tested. Maximum grip exertions were evaluated for sixteen subjects gripping cylindrical handles varying in diameter. Results Mean grip force magnitudes were 231 N (SD=67.7 N), 236 N (72.9 N), 208 N (72.5 N), and 158 N (45.7 N) for 3.81 cm, 5.08 cm, 6.35 cm and 7.62 cm diameter handles, respectively. Grip force direction rotated clockwise and the centre of pressure moved upward along the handle as handle diameter increased. Conclusions Given that the multi-axis dynamometer simultaneously measures planar grip force magnitude and direction, and centre of pressure along the handle, this novel sensor design provides more grip force characteristics than current sensor designs that would improve evaluation of grip characteristics and model-driven calculations of musculoskeletal forces from dynamometer data. PMID:24134054

  5. 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…

  6. 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.

  7. Satellite Dynamic Damping via Active Force Control Augmentation

    NASA Astrophysics Data System (ADS)

    Varatharajoo, Renuganth

    2012-07-01

    An approach that incorporates the Active Force Control (AFC) technique into a conventional Proportional-Derivative (PD) controller is proposed for a satellite active dynamic damping towards a full attitude control. The AFC method has been established to facilitate a robust motion control of dynamical systems in the presence of disturbances, parametric uncertainties and changes that are commonly prevalent in the real-world environment. The usefulness of the method can be extended by introducing intelligent mechanisms to approximate the mass or inertia matrix of the dynamic system to trigger the compensation effect of the controller. AFC is a technique that relies on the appropriate estimation of the inertial or mass parameters of the dynamic system and the measurements of the acceleration and force signals induced by the system if practical implementation is ever considered. In AFC, it is shown that the system subjected to a number of disturbances remains stable and robust via the compensating action of the control strategy. We demonstrate that it is possible to design a spacecraft attitude feedback controller that will ensure the system dynamics set point remains unchanged even in the presence of the disturbances provided that the actual disturbances can be modeled effectively. In order to further facilitate this analysis, a combined energy and attitude control system (CEACS) is proposed as a model satellite attitude control actuator. All the governing equations are established and the proposed satellite attitude control architecture is made amenable to numerical treatments. The results show that the PD-AFC attitude damping performances are superiorly better than that of the solely PD type. It is also shown that the tunings of the AFC system gains are crucial to ensure a better attitude damping performance and this process is mandatory for AFC systems. Finally, the results demonstrate an important satellite dynamic damping enhancement capability using the AFC

  8. 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.

  9. Automated conformational energy fitting for force-field development

    PubMed Central

    Guvench, Olgun; MacKerell, Alexander D.

    2010-01-01

    We present a general conformational-energy fitting procedure based on Monte Carlo simulated annealing (MCSA) for application in the development of molecular mechanics force fields. Starting with a target potential energy surface and an unparameterized molecular mechanics potential energy surface, an optimized set of either dihedral or grid-based correction map (CMAP) parameters is produced that minimizes the root mean squared error (RMSE) between the parameterized and targeted energies. The fitting is done using an MCSA search in parameter space and consistently converges to the same RMSE irrespective of the randomized parameters used to seed the search. Any number of dihedral parameters can be simultaneously parameterized, allowing for fitting to multi-dimensional potential energy scans. Fitting options for dihedral parameters include non-uniform weighting of the target data, constraining multiple optimized parameters to the same value, constraining parameters to be no greater than a user-specified maximum value, including all or only a subset of multiplicities defining the dihedral Fourier series, and optimization of phase angles in addition to force constants. The dihedral parameter fitting algorithm’s performance is characterized through multi-dimensional fitting of cyclohexane, tetrahydropyran, and hexopyranose monosaccharide energetics, with the latter case having a 30-dimensional parameter space. The CMAP fitting is applied in the context of polypeptides, and is used to develop a parameterization that simultaneously captures the φ, ψ energetics of the alanine dipeptide and the alanine tetrapeptide. Because the dihedral energy term is common to many force fields, we have implemented the dihedral-fitting algorithm in the portable Python scripting language and have made it freely available as Supplementary Material. PMID:18458967

  10. 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.

  11. Air Force Satellite Control Network and SDI development

    NASA Astrophysics Data System (ADS)

    Bleier, T.

    The Air Force Satellite Control Network (AFSCN) represents a military, worldwide network of control centers and remote tracking sites (RTS). A relatively large and growing constellation of DOD satellites is supported. The near term and long term plans for the AFSCN are discussed, taking into account also the impact of the Space Defense Initiative (SDI) on the AFSCN. It is pointed out that the SDI adds a new dimension to the support provided by the AFSCN to the DOD satellites, because some SDI scenarios being considered include many more satellite platforms, each containing multiple kinetic energy weapons. Space-ground link sites are discussed along with AFSCN control sites, and communication between RTS and control centers. Attention is given to changing roles and responsibilities, the Satellite Test Center (STC) as an excellent site for the R and D phase of SDI development, and an operational concept for a highly proliferated weapons platforms architecture, and goals of developing more survivable satellite systems.

  12. Development of the CHARMM Force Field for Lipids

    PubMed Central

    Pastor, R.W.; MacKerell, A.D.

    2011-01-01

    The development of the CHARMM additive all-atom lipid force field (FF) is traced from the early 1990’s to the most recent version (C36) published in 2010. Though simulations with early versions yielded useful results, they failed to reproduce two important quantities: a zero surface tension at the experimental bilayer surface area, and the signature splitting of the deuterium order parameters in the glycerol and upper chain carbons. Systematic optimization of parameters based on high level quantum mechanical data and free energy simulations have resolved these issues, and bilayers with a wide range of lipids can be simulated in tensionless ensembles using C36. Issues associated with other all-atom lipid FFs, success and limitations in the C36 FF and ongoing developments are also discussed. PMID:21760975

  13. 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.

  14. 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.

  15. 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.

  16. 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…

  17. Development of force field parameters for molecular simulation of polylactide

    PubMed Central

    McAliley, James H.; Bruce, David A.

    2011-01-01

    Polylactide is a biodegradable polymer that is widely used for biomedical applications, and it is a replacement for some petroleum based polymers in applications that range from packaging to carpeting. Efforts to characterize and further enhance polylactide based systems using molecular simulations have to this point been hindered by the lack of accurate atomistic models for the polymer. Thus, we present force field parameters specifically suited for molecular modeling of PLA. The model, which we refer to as PLAFF3, is based on a combination of the OPLS and CHARMM force fields, with modifications to bonded and nonbonded parameters. Dihedral angle parameters were adjusted to reproduce DFT data using newly developed CMAP dihedral cross terms, and the model was further adjusted to reproduce experimentally resolved crystal structure conformations, melt density, volume expansivity, and the glass transition temperature of PLA. We recommend the use of PLAFF3 in modeling PLA in its crystalline or amorphous states and have provided the necessary input files required for the publicly available molecular dynamics code GROMACS. PMID:22180734

  18. Ciliary muscle contraction force and trapezius muscle activity during manual tracking of a moving visual target.

    PubMed

    Domkin, Dmitry; Forsman, Mikael; Richter, Hans O

    2016-06-01

    Previous studies have shown an association of visual demands during near work and increased activity of the trapezius muscle. Those studies were conducted under stationary postural conditions with fixed gaze and artificial visual load. The present study investigated the relationship between ciliary muscle contraction force and trapezius muscle activity across individuals during performance of a natural dynamic motor task under free gaze conditions. Participants (N=11) tracked a moving visual target with a digital pen on a computer screen. Tracking performance, eye refraction and trapezius muscle activity were continuously measured. Ciliary muscle contraction force was computed from eye accommodative response. There was a significant Pearson correlation between ciliary muscle contraction force and trapezius muscle activity on the tracking side (0.78, p<0.01) and passive side (0.64, p<0.05). The study supports the hypothesis that high visual demands, leading to an increased ciliary muscle contraction during continuous eye-hand coordination, may increase trapezius muscle tension and thus contribute to the development of musculoskeletal complaints in the neck-shoulder area. Further experimental studies are required to clarify whether the relationship is valid within each individual or may represent a general personal trait, when individuals with higher eye accommodative response tend to have higher trapezius muscle activity. PMID:26746010

  19. Development of forced flow cooled current leads for fusion magnets

    NASA Astrophysics Data System (ADS)

    Heller, R.; Fink, S.; Friesinger, G.; Kienzler, A.; Lingor, A.; Schleinkofer, G.; Süßer, M.; Ulbricht, A.; Wüchner, F.; Zahn, G.

    2001-03-01

    During the past 15 years, the Institut für Technische Physik of the Forschungszentrum Karlsruhe, Germany, has developed current leads cooled by forced-flow supercritical helium in the current range from 20 to 80 kA. The design is based on a separation of the current carrying part and the heat exchanger part as well as the presence of the so-called superconductor inserts made of Nb 3Sn wires inside the conductor in the heat exchanger area which allows the operation of the current lead at minimum helium mass flow in a wide current range. The paper describes the design and construction of the current leads as well as operation results obtained during various tests performed in the coil test facility TOSKA at the Forschungszentrum Karlsruhe.

  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. PMID:12336488

  1. Forced-exercise delays neuropathic pain in experimental diabetes: effects on voltage-activated calcium channels.

    PubMed

    Shankarappa, Sahadev A; Piedras-Rentería, Erika S; Stubbs, Evan B

    2011-07-01

    Physical exercise produces a variety of psychophysical effects, including altered pain perception. Elevated levels of centrally produced endorphins or endocannabinoids are implicated as mediators of exercise-induced analgesia. The effect of exercise on the development and persistence of disease-associated acute/chronic pain remains unclear. In this study, we quantified the physiological consequence of forced-exercise on the development of diabetes-associated neuropathic pain. Euglycemic control or streptozotocin (STZ)-induced diabetic adult male rats were subdivided into sedentary or forced-exercised (2-10 weeks, treadmill) subgroups and assessed for changes in tactile responsiveness. Two weeks following STZ-treatment, sedentary rats developed a marked and sustained hypersensitivity to von Frey tactile stimulation. By comparison, STZ-treated diabetic rats undergoing forced-exercise exhibited a 4-week delay in the onset of tactile hypersensitivity that was independent of glucose control. Exercise-facilitated analgesia in diabetic rats was reversed, in a dose-dependent manner, by naloxone. Small-diameter (< 30 μm) DRG neurons harvested from STZ-treated tactile hypersensitive diabetic rats exhibited an enhanced (2.5-fold) rightward (depolarizing) shift in peak high-voltage activated (HVA) Ca(2+) current density with a concomitant appearance of a low-voltage activated (LVA) Ca(2+) current component. LVA Ca(2+) currents present in DRG neurons from hypersensitive diabetic rats exhibited a marked depolarizing shift in steady-state inactivation. Forced-exercise attenuated diabetes-associated changes in HVA Ca(2+) current density while preventing the depolarizing shift in steady-state inactivation of LVA Ca(2+) currents. Forced-exercise markedly delays the onset of diabetes-associated neuropathic pain, in part, by attenuating associated changes in HVA and LVA Ca(2+) channel function within small-diameter DRG neurons possibly by altering opioidergic tone. PMID:21554321

  2. 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

  3. Passive Joint Forces Are Tuned to Limb Use in Insects and Drive Movements without Motor Activity

    PubMed Central

    Ache, Jan M.; Matheson, Thomas

    2013-01-01

    Summary Background Limb movements are generally driven by active muscular contractions working with and against passive forces arising in muscles and other structures. In relatively heavy limbs, the effects of gravity and inertia predominate, whereas in lighter limbs, passive forces intrinsic to the limb are of greater consequence. The roles of passive forces generated by muscles and tendons are well understood, but there has been little recognition that forces originating within joints themselves may also be important, and less still that these joint forces may be adapted through evolution to complement active muscle forces acting at the same joint. Results We examined the roles of passive joint forces in insect legs with different arrangements of antagonist muscles. We first show that passive forces modify actively generated movements of a joint across its working range, and that they can be sufficiently strong to generate completely passive movements that are faster than active movements observed in natural behaviors. We further demonstrate that some of these forces originate within the joint itself. In legs of different species adapted to different uses (walking, jumping), these passive joint forces complement the balance of strength of the antagonist muscles acting on the joint. We show that passive joint forces are stronger where they assist the weaker of two antagonist muscles. Conclusions In limbs where the dictates of a key behavior produce asymmetry in muscle forces, passive joint forces can be coadapted to provide the balance needed for the effective generation of other behaviors. PMID:23871240

  4. High force development augments skeletal muscle signalling in resistance exercise modes equalized for time under tension.

    PubMed

    Gehlert, Sebastian; Suhr, Frank; Gutsche, Katrin; Willkomm, Lena; Kern, Julia; Jacko, Daniel; Knicker, Axel; Schiffer, Thorsten; Wackerhage, Henning; Bloch, Wilhelm

    2015-06-01

    How force development and time under tension (TUT) during resistance exercise (RE) influence anabolic signalling of skeletal muscle is incompletely understood. We hypothesized that high force development during RE is more important for post-exercise-induced signalling than submaximal and fatiguing RE with lower force development but similar TUT. Twenty-two male subjects (24 ± 6 years, 181 ± 9 cm, 79 ± 2 kg) performed three distinct RE modes in the fed state with equal TUT but distinct force output: (i) maximal eccentric RE (ECC, n = 7) three sets, eight reps, 100% eccentric dynamic force; (ii) standard RE (STD, n = 7), three sets, 10 reps, 75% dynamic force; and (iii) high fatiguing single-set RE (HIT, n = 8), 20 reps, 100% eccentric-concentric force; vastus lateralis biopsies were collected at baseline, 15, 30, 60, 240 min and 24 h after RE, and the signalling of mechanosensitive and mammalian target of rapamycin (mTOR)-related proteins was determined. The phosphorylation levels of pFAK(Tyr397), pJNK(Thr183/Tyr185), pAKT(Thr308/Ser473), pmTOR(Ser2448), p4E-BP1(Thr37/46), p70s6k(Thr389)/(Ser421/Thr424) and pS6(Ser235/236) were significantly higher in ECC than those in STD and HIT at several time points (P < 0.01). pJNK(Thr183/Tyr185) and pS6(Ser235/236) levels were significantly higher in type II myofibres in ECC compared with STD and HIT. HIT exerted throughout the weakest signalling response. We conclude that high force development during acute RE is superior for anabolic skeletal muscle signalling than fatiguing RE with lower force output but similar TUT. Our results suggest that this response is substantially driven by the higher activation of type II myofibres during RE. PMID:25070178

  5. 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).

  6. 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…

  7. 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…

  8. Dynamic Allostery of the Catabolite Activator Protein Revealed by Interatomic Forces

    PubMed Central

    Louet, Maxime; Seifert, Christian; Hensen, Ulf; Gräter, Frauke

    2015-01-01

    The Catabolite Activator Protein (CAP) is a showcase example for entropic allostery. For full activation and DNA binding, the homodimeric protein requires the binding of two cyclic AMP (cAMP) molecules in an anti-cooperative manner, the source of which appears to be largely of entropic nature according to previous experimental studies. We here study at atomic detail the allosteric regulation of CAP with Molecular dynamics (MD) simulations. We recover the experimentally observed entropic penalty for the second cAMP binding event with our recently developed force covariance entropy estimator and reveal allosteric communication pathways with Force Distribution Analyses (FDA). Our observations show that CAP binding results in characteristic changes in the interaction pathways connecting the two cAMP allosteric binding sites with each other, as well as with the DNA binding domains. We identified crucial relays in the mostly symmetric allosteric activation network, and suggest point mutants to test this mechanism. Our study suggests inter-residue forces, as opposed to coordinates, as a highly sensitive measure for structural adaptations that, even though minute, can very effectively propagate allosteric signals. PMID:26244893

  9. Dynamic Allostery of the Catabolite Activator Protein Revealed by Interatomic Forces.

    PubMed

    Louet, Maxime; Seifert, Christian; Hensen, Ulf; Gräter, Frauke

    2015-08-01

    The Catabolite Activator Protein (CAP) is a showcase example for entropic allostery. For full activation and DNA binding, the homodimeric protein requires the binding of two cyclic AMP (cAMP) molecules in an anti-cooperative manner, the source of which appears to be largely of entropic nature according to previous experimental studies. We here study at atomic detail the allosteric regulation of CAP with Molecular dynamics (MD) simulations. We recover the experimentally observed entropic penalty for the second cAMP binding event with our recently developed force covariance entropy estimator and reveal allosteric communication pathways with Force Distribution Analyses (FDA). Our observations show that CAP binding results in characteristic changes in the interaction pathways connecting the two cAMP allosteric binding sites with each other, as well as with the DNA binding domains. We identified crucial relays in the mostly symmetric allosteric activation network, and suggest point mutants to test this mechanism. Our study suggests inter-residue forces, as opposed to coordinates, as a highly sensitive measure for structural adaptations that, even though minute, can very effectively propagate allosteric signals. PMID:26244893

  10. Algorithm for automatic forced spirometry quality assessment: technological developments.

    PubMed

    Melia, Umberto; Burgos, Felip; Vallverdú, Montserrat; Velickovski, Filip; Lluch-Ariet, Magí; Roca, Josep; Caminal, Pere

    2014-01-01

    We hypothesized that the implementation of automatic real-time assessment of quality of forced spirometry (FS) may significantly enhance the potential for extensive deployment of a FS program in the community. Recent studies have demonstrated that the application of quality criteria defined by the ATS/ERS (American Thoracic Society/European Respiratory Society) in commercially available equipment with automatic quality assessment can be markedly improved. To this end, an algorithm for assessing quality of FS automatically was reported. The current research describes the mathematical developments of the algorithm. An innovative analysis of the shape of the spirometric curve, adding 23 new metrics to the traditional 4 recommended by ATS/ERS, was done. The algorithm was created through a two-step iterative process including: (1) an initial version using the standard FS curves recommended by the ATS; and, (2) a refined version using curves from patients. In each of these steps the results were assessed against one expert's opinion. Finally, an independent set of FS curves from 291 patients was used for validation purposes. The novel mathematical approach to characterize the FS curves led to appropriate FS classification with high specificity (95%) and sensitivity (96%). The results constitute the basis for a successful transfer of FS testing to non-specialized professionals in the community. PMID:25551213

  11. Algorithm for Automatic Forced Spirometry Quality Assessment: Technological Developments

    PubMed Central

    Melia, Umberto; Burgos, Felip; Vallverdú, Montserrat; Velickovski, Filip; Lluch-Ariet, Magí; Roca, Josep; Caminal, Pere

    2014-01-01

    We hypothesized that the implementation of automatic real-time assessment of quality of forced spirometry (FS) may significantly enhance the potential for extensive deployment of a FS program in the community. Recent studies have demonstrated that the application of quality criteria defined by the ATS/ERS (American Thoracic Society/European Respiratory Society) in commercially available equipment with automatic quality assessment can be markedly improved. To this end, an algorithm for assessing quality of FS automatically was reported. The current research describes the mathematical developments of the algorithm. An innovative analysis of the shape of the spirometric curve, adding 23 new metrics to the traditional 4 recommended by ATS/ERS, was done. The algorithm was created through a two-step iterative process including: (1) an initial version using the standard FS curves recommended by the ATS; and, (2) a refined version using curves from patients. In each of these steps the results were assessed against one expert's opinion. Finally, an independent set of FS curves from 291 patients was used for validation purposes. The novel mathematical approach to characterize the FS curves led to appropriate FS classification with high specificity (95%) and sensitivity (96%). The results constitute the basis for a successful transfer of FS testing to non-specialized professionals in the community. PMID:25551213

  12. 76 FR 56863 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-14

    ... ADMINISTRATION Interagency Task Force on Veterans Small Business Development AGENCY: U.S. Small Business... Task Force on Veterans Small Business Development. The meeting will be open to the public. DATES... U.S.C., Appendix 2), SBA announces the meeting of the Interagency Task Force on Veterans...

  13. 76 FR 21090 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-14

    ... ADMINISTRATION Interagency Task Force on Veterans Small Business Development AGENCY: U.S. Small Business... Task Force on Veterans Small Business Development. The meeting will be open to the public. DATES...., Appendix 2), SBA announces the meeting of the Interagency Task Force on Veterans Small Business...

  14. 75 FR 75187 - Interagency Task Force on Veterans Small Business Development Meeting Notice

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-02

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

  15. 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:...

  16. 75 FR 62438 - Interagency Task Force on Veterans Small Business Development Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-08

    ... ADMINISTRATION Interagency Task Force on Veterans Small Business Development Meeting 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....

  17. 78 FR 7849 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-04

    ... 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:...

  18. 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....

  19. 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....

  20. 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....

  1. 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...

  2. 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:...

  3. 77 FR 1548 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-10

    ... ADMINISTRATION Interagency Task Force on Veterans Small Business Development AGENCY: U.S. Small Business... Task Force on Veterans Small Business Development. The meeting will be open to the public. DATES... Federal government. On November 1, 2011, The Interagency Task Force on Veterans Small Business...

  4. 77 FR 22056 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-12

    ... ADMINISTRATION Interagency Task Force on Veterans Small Business Development AGENCY: U.S. Small Business... Task Force on Veterans Small Business Development. The meeting will be open to the public. DATES... 2), SBA announces the meeting of the Interagency Task Force on Veterans Small Business...

  5. 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....

  6. 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.

  7. Educational Development and Knowledge Flow: Local and Global Forces in Human Development in Africa

    ERIC Educational Resources Information Center

    Nsamenang, A. Bame

    2005-01-01

    Both local and global forces impact on educational and human development. This disrupts Africa's capacity to own, generate, and share knowledge. A disorganizing hybridism between African, Eastern and Western heritages exacerbates the difficulty. A social Darwinian perspective disparages but exploits Africanity. Furthermore, no extant theory…

  8. 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

  9. 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)

  10. Force and power generating mechanism(s) in active muscle as revealed from temperature perturbation studies.

    PubMed

    Ranatunga, K W

    2010-10-01

    The basic characteristics of the process of force and power generation in active muscle that have emerged from temperature studies are examined. This is done by reviewing complementary findings from temperature-dependence studies and rapid temperature-jump (T-jump) experiments and from intact and skinned fast mammalian muscle fibres. In isometric muscle, a small T-jump leads to a characteristic rise in force showing that crossbridge force generation is endothermic (heat absorbed) and associated with increased entropy (disorder). The sensitivity of the T-jump force generation to added inorganic phosphate (Pi) indicates that a T-jump enhances an early step in the actomyosin (crossbridge) ATPase cycle before Pi-release. During muscle lengthening when steady force is increased, the T-jump force generation is inhibited. Conversely, during shortening when steady force is decreased, the T-jump force generation is enhanced in a velocity-dependent manner, showing that T-jump force generation is strain sensitive. Within the temperature range of ∼5–35◦C, the temperature dependence of steady active force is sigmoidal both in isometric and in shortening muscle. However, in shortening muscle, the endothermic character of force generation becomes more pronounced with increased velocity and this can, at least partly, account for the marked increase with warming of the mechanical power output of active muscle. PMID:20660565

  11. 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...

  12. Evaluation of Force Degradation Pattern of Elastomeric Ligatures and Elastomeric Separators in Active Tieback State

    PubMed Central

    Mohammadi, Amir; Mahmoodi, Farhang

    2015-01-01

    Background and aims. The purpose of this study was to evaluate initial force and force decay of commercially available elastomeric ligatures and elastomeric separators in active tieback state in a simulated oral environment. Materials and methods. A total of 288 elastomeric ligatures and elastomeric separators from three manufacturers (Dentaurum, RMO, 3M Unitek) were stretched to 100% and 150% of their original inner diameter. Force levels were measured initially and at 3-minute, 24-hour, and 1-, 2-, 3- and 4-week intervals. Data were analyzed by univariate analysis of variance and a post hoc Tukey test. Results. The means of initial forces of elastomeric ligatures and separators from three above-mentioned companies, when stretched to 100% of their inner diameters, were 199, 305 and 284 g, and 330, 416, 330 g; when they were stretched to 150% of their inner diameters the values were 286, 422 and 375 g, and 433, 540 and 504 g, respectively. In active tieback state, 11-18% of the initial force of the specimens was lost within the first 3 minutes and 29-63% of the force decay occurred in the first 24 hours; then force decay rate decreased. 62-81% of the initial force was lost in 4 weeks. Although force decay pattern was identical in all the products, the initial force and force decay of Dentaurum elastomeric products were less than the similar products of other companies (P<0.05). Under the same conditions, the force of elastomeric separators was greater than elastomeric ligatures of the same company. Conclusion. Regarding the force pattern of elastomeric ligatures and separators and optimal force for tooth movement, many of these products can be selected for applying orthodontic forces in active tieback state. PMID:26889363

  13. Evaluation of Force Degradation Pattern of Elastomeric Ligatures and Elastomeric Separators in Active Tieback State.

    PubMed

    Mohammadi, Amir; Mahmoodi, Farhang

    2015-01-01

    Background and aims. The purpose of this study was to evaluate initial force and force decay of commercially available elastomeric ligatures and elastomeric separators in active tieback state in a simulated oral environment. Materials and methods. A total of 288 elastomeric ligatures and elastomeric separators from three manufacturers (Dentaurum, RMO, 3M Unitek) were stretched to 100% and 150% of their original inner diameter. Force levels were measured initially and at 3-minute, 24-hour, and 1-, 2-, 3- and 4-week intervals. Data were analyzed by univariate analysis of variance and a post hoc Tukey test. Results. The means of initial forces of elastomeric ligatures and separators from three above-mentioned companies, when stretched to 100% of their inner diameters, were 199, 305 and 284 g, and 330, 416, 330 g; when they were stretched to 150% of their inner diameters the values were 286, 422 and 375 g, and 433, 540 and 504 g, respectively. In active tieback state, 11-18% of the initial force of the specimens was lost within the first 3 minutes and 29-63% of the force decay occurred in the first 24 hours; then force decay rate decreased. 62-81% of the initial force was lost in 4 weeks. Although force decay pattern was identical in all the products, the initial force and force decay of Dentaurum elastomeric products were less than the similar products of other companies (P<0.05). Under the same conditions, the force of elastomeric separators was greater than elastomeric ligatures of the same company. Conclusion. Regarding the force pattern of elastomeric ligatures and separators and optimal force for tooth movement, many of these products can be selected for applying orthodontic forces in active tieback state. PMID:26889363

  14. Negative emotions facilitate isometric force through activation of prefrontal cortex and periaqueductal gray.

    PubMed

    Blakemore, Rebekah L; Rieger, Sebastian W; Vuilleumier, Patrik

    2016-01-01

    Emotions are considered to modulate action readiness. Previous studies have demonstrated increased force production following exposure to emotionally arousing visual stimuli; however the neural mechanisms underlying how precise force output is controlled within varying emotional contexts remain poorly understood. To identify the neural correlates of emotion-modulated motor behaviour, twenty-two participants produced a submaximal isometric precision-grip contraction while viewing pleasant, unpleasant, neutral or blank images (without visual feedback of force output). Force magnitude was continuously recorded together with change in brain activity using functional magnetic resonance imaging. Viewing unpleasant images resulted in reduced force decay during force maintenance as compared with pleasant, neutral and blank images. Subjective valence and arousal ratings significantly predicted force production during maintenance. Neuroimaging revealed that negative valence and its interaction with force output correlated with increased activity in right inferior frontal gyrus (rIFG), while arousal was associated with amygdala and periaqueductal gray (PAG) activation. Force maintenance alone was correlated with cerebellar activity. These data demonstrate a valence-driven modulation of force output, mediated by a cortico-subcortical network involving rIFG and PAG. These findings are consistent with engagement of motor pathways associated with aversive motivation, eliciting defensive behaviour and action preparedness in response to negative emotional signals. PMID:26400014

  15. Development of an active structure flight experiment

    NASA Astrophysics Data System (ADS)

    Manning, R. A.; Wyse, R. E.; Schubert, S. R.

    1993-02-01

    The design and development of the Air Force and TRW's Advanced Control Technology Experiment (ACTEX) flight experiment is described in this paper. The overall objective of ACTEX is to provide an active structure trailblazer which will demonstrate the compatibility of active structures with operational spacecraft performance and lifetime measures. At the heart of the experiment is an active tripod driven by a digitally-programmable analog control electronics subsystem. Piezoceramic sensors and actuators embedded in a graphite epoxy host material provide the sensing and actuation mechanism for the active tripod. Low noise ground-programmable electronics provide a virtually unlimited number of control schemes that can be implemented in the space environment. The flight experiment program provides the opportunity to gather performance, reliability, adaptability, and lifetime performance data on vibration suppression hardware for the next generation of DoD and NASA spacecraft.

  16. 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

  17. 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. PMID:26349916

  18. Force modulation atomic force microscopy: background, development and application to electrodeposited cerium oxide films

    NASA Astrophysics Data System (ADS)

    Li, Feng-Bin; Thompson, G. E.; Newman, R. C.

    1998-04-01

    In force modulation atomic force microscopy (FMAFM), vertical oscillation of the scanning tip of the AFM is added purposely and the deflection of the tip, which is influenced by surface features of the sample, is used as the z dimension to construct images. FMAFM represents a powerful technique for scientific research, but its merit has not been realized adequately to date. In this paper, the basic principles and particular features, as well as potential drawbacks of the technique, are presented and demonstrated systematically, through its application to electrochemically deposited cerium oxide films. Comparisons are also made with the more familiar contact mode AFM (CMAFM) and tapping mode AFM (TMAFM). It is shown that FMAFM reveals the major topographic features of CMAFM, but affords (i) greater resolution for sample features that are difficult in CMAFM, and (ii) continuous two-dimensional mapping of local mechanical properties on a scale of nanometres that the CMAFM, TMAFM and any other techniques, are not capable of sensing. This information can be used to elucidate other properties of the investigated surface, such as crystallinity variation, phase separation and distribution, and mechanisms of formation of deposited films. Major artifacts associated with the technique include `wedge cavity effect' and `tip slip effect', for which a geometric model is proposed to elucidate their origins. The cerium oxide films are shown to be composed of relatively hard crystalline grains, of well-defined individual geometry and comparatively regular packing, alongside relatively soft amorphous patches, devoid of distinct geometry and assembled disorderly. These features are consistent with a nucleation and growth mechanism of the deposition, in which crystalline nuclei arise and grow from an intermediate cerium gel mass, produced in the interfacial region during deposition.

  19. 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. PMID:19400368

  20. 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

  1. Active design method for the static characteristics of a piezoelectric six-axis force/torque sensor.

    PubMed

    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

  2. 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

  3. Ground reaction forces and lower-limb joint kinetics of turning gait in typically developing children.

    PubMed

    Dixon, Philippe C; Stebbins, Julie; Theologis, Tim; Zavatsky, Amy B

    2014-11-28

    Turning is a common locomotor task essential to daily activity; however, very little is known about the forces and moments responsible for the kinematic adaptations occurring relative to straight-line gait in typically developing children. Thus, the aims of this study were to analyse ground reaction forces (GRFs), ground reaction free vertical torque (TZ), and the lower-limb joint kinetics of 90° outside (step) and inside (spin) limb turns. Step, spin, and straight walking trials from fifty-four typically developing children were analysed. All children were fit with the Plug-in Gait and Oxford Foot Model marker sets while walking over force plates embedded in the walkway. Net internal joint moments and power were computed via a standard inverse dynamics approach. All dependent variables were statistically analysed over the entire curves using the mean difference 95% bootstrap confidence band approach. GRFs were directed medially for step turns and laterally for spin turns during the turning phase. Directions were reversed and magnitudes decreased during the approach phase. Step turns showed reduced ankle power generation, while spin turns showed large TZ. Both strategies required large knee and hip coronal and transverse plane moments during swing. These kinetic differences highlight adaptations required to maintain stability and reorient the body towards the new walking direction during turning. From a clinical perspective, turning gait may better reveal weaknesses and motor control deficits than straight walking in pathological populations, such as children with cerebral palsy, and could potentially be implemented in standard gait analysis sessions. PMID:25311452

  4. Dissociation of Calcium Transients and Force Development following a Change in Stimulation Frequency in Isolated Rabbit Myocardium

    PubMed Central

    Haizlip, Kaylan M.; Milani-Nejad, Nima; Varian, Kenneth D.; Slabaugh, Jessica L.; Walton, Shane D.; Gyorke, Sandor; Davis, Jonathan P.; Biesiadecki, Brandon J.; Janssen, Paul M. L.

    2015-01-01

    As the heart transitions from one exercise intensity to another, changes in cardiac output occur, which are modulated by alterations in force development and calcium handling. Although the steady-state force-calcium relationship at various heart rates is well investigated, regulation of these processes during transitions in heart rate is poorly understood. In isolated right ventricular muscle preparations from the rabbit, we investigated the beat-to-beat alterations in force and calcium during the transition from one stimulation frequency to another, using contractile assessments and confocal microscopy. We show that a change in steady-state conditions occurs in multiple phases: a rapid phase, which is characterized by a fast change in force production mirrored by a change in calcium transient amplitude, and a slow phase, which follows the rapid phase and occurs as the muscle proceeds to stabilize at the new frequency. This second/late phase is characterized by a quantitative dissociation between the calcium transient amplitude and developed force. Twitch timing kinetics, such as time to peak tension and 50% relaxation rate, reached steady-state well before force development and calcium transient amplitude. The dynamic relationship between force and calcium upon a switch in stimulation frequency unveils the dynamic involvement of myofilament-based properties in frequency-dependent activation. PMID:25961020

  5. 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

  6. Estimating youth locomotion ground reaction forces using an accelerometer-based activity monitor.

    PubMed

    Neugebauer, Jennifer M; Hawkins, David A; Beckett, Laurel

    2012-01-01

    To address a variety of questions pertaining to the interactions between physical activity, musculoskeletal loading and musculoskeletal health/injury/adaptation, simple methods are needed to quantify, outside a laboratory setting, the forces acting on the human body during daily activities. The purpose of this study was to develop a statistically based model to estimate peak vertical ground reaction force (pVGRF) during youth gait. 20 girls (10.9 ± 0.9 years) and 15 boys (12.5 ± 0.6 years) wore a Biotrainer AM over their right hip. Six walking and six running trials were completed after a standard warm-up. Average AM intensity (g) and pVGRF (N) during stance were determined. Repeated measures mixed effects regression models to estimate pVGRF from Biotrainer activity monitor acceleration in youth (girls 10-12, boys 12-14 years) while walking and running were developed. Log transformed pVGRF had a statistically significant relationship with activity monitor acceleration, centered mass, sex (girl), type of locomotion (run), and locomotion type-acceleration interaction controlling for subject as a random effect. A generalized regression model without subject specific random effects was also developed. The average absolute differences between the actual and predicted pVGRF were 5.2% (1.6% standard deviation) and 9% (4.2% standard deviation) using the mixed and generalized models, respectively. The results of this study support the use of estimating pVGRF from hip acceleration using a mixed model regression equation. PMID:23133564

  7. 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…

  8. 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…

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

    PubMed

    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

  10. 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

  11. Developments of new force reflecting control schemes and an application to a teleoperation training simulator

    NASA Technical Reports Server (NTRS)

    Kim, Won S.

    1992-01-01

    Two schemes of force reflecting control, position-error based force reflection and low-pass-filtered force reflection, both combined with shared compliance control, were developed for dissimilar master-slave arms. These schemes enabled high force reflection gains, which were not possible with a conventional scheme when the slave arm was much stiffer than the master arm. The experimental results with a peg-in-hole task indicated that the newly force reflecting control schemes combined with compliance control resulted in best task performances. As a related application, a simulated force reflection/shared compliance control teleoperation trainer was developed that provided the operator with the feel of kinesthetic force virtual reality.

  12. 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

  13. 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. PMID:26240657

  14. An Ungrounded Hand-Held Surgical Device Incorporating Active Constraints with Force-Feedback

    PubMed Central

    Payne, Christopher J.; Kwok, Ka-Wai; Yang, Guang-Zhong

    2014-01-01

    This paper presents an ungrounded, hand-held surgical device that incorporates active constraints and force-feedback. Optical tracking of the device and embedded actuation allow for real-time motion compensation of a surgical tool as an active constraint is encountered. The active constraints can be made soft, so that the surgical tool tip motion is scaled, or rigid, so as to altogether prevent the penetration of the active constraint. Force-feedback is also provided to the operator so as to indicate penetration of the active constraint boundary by the surgical tool. The device has been evaluated in detailed bench tests to quantify its motion scaling and force-feedback capabilities. The combined effects of force-feedback and motion compensation are demonstrated during palpation of an active constraint with rigid and soft boundaries. A user study evaluated the combined effect of motion compensation and force-feedback in preventing penetration of a rigid active constraint. The results have shown the potential of the device operating in an ungrounded setup that incorporates active constraints with force-feedback. PMID:24744963

  15. Nonexercise activity thermogenesis--liberating the life-force.

    PubMed

    Levine, J A

    2007-09-01

    Obesity occurs when energy intake exceeds energy expenditure over a protracted period of time. The energy expenditure associated with everyday activity is called NEAT (Nonexercise activity thermogenesis). NEAT varies between two people of similar size by 2000 kcal day(-1) because of people's different occupations and leisure-time activities. Data support the central hypothesis that NEAT is pivotal in the regulation of human energy expenditure and body weight regulation and that NEAT is important for understanding the cause and effective treatment for obesity. PMID:17697152

  16. 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.

  17. 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.…

  18. 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

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

    PubMed

    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

  20. 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. PMID:25408069

  1. Laser-communication cooperative research and development agreement between Air Force Phillips Lab and Ball Aerospace

    NASA Astrophysics Data System (ADS)

    Begley, David L.; Kehr, Robert L.; Sarto, Anthony W.; Casey, William; Coffelt, Everett L.; Goodrich, Alan; Thompson, William E.

    1997-04-01

    This paper presents an overview of a cooperative research and development program between Ball Aerospace and Technologies Corp. and the Air Force Phillips Laboratory for laser communications. This effort employs hardware and equipment originally developed to support the crosslinking between geostationary Defense Support Program surveillance satellites. This joint activity modifies the existing hardware for ground based demonstrations and simulations focuses at risk reduction for future applications and technology insertion into operational architectures meeting future commercial, civil, and DOD communications requirements. The ultimate goal of the program is to produce hardware for a near term flight demonstration. A brief overview of the capabilities of the existing hardware will be presented followed by a status of the development efforts and future plans.

  2. Active mechanics in living oocytes reveal molecular-scale force kinetics

    NASA Astrophysics Data System (ADS)

    Ahmed, Wylie; Fodor, Etienne; Almonacid, Maria; Bussonnier, Matthias; Verlhac, Marie-Helene; Gov, Nir; Visco, Paolo; van Wijland, Frederic; Betz, Timo

    Unlike traditional materials, living cells actively generate forces at the molecular scale that change their structure and mechanical properties. This nonequilibrium activity is essential for cellular function, and drives processes such as cell division. Single molecule studies have uncovered the detailed force kinetics of isolated motor proteins in-vitro, however their behavior in-vivo has been elusive due to the complex environment inside the cell. Here, we quantify active forces and intracellular mechanics in living oocytes using in-vivo optical trapping and laser interferometry of endogenous vesicles. We integrate an experimental and theoretical framework to connect mesoscopic measurements of nonequilibrium properties to the underlying molecular- scale force kinetics. Our results show that force generation by myosin-V drives the cytoplasmic-skeleton out-of-equilibrium (at frequencies below 300 Hz) and actively softens the environment. In vivo myosin-V activity generates a force of F ~ 0 . 4 pN, with a power-stroke of length Δx ~ 20 nm and duration τ ~ 300 μs, that drives vesicle motion at vv ~ 320 nm/s. This framework is widely applicable to characterize living cells and other soft active materials.

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

    PubMed

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

    2015-01-01

    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. PMID:26037312

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

    PubMed Central

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

    2015-01-01

    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 Ca2+- and MgADP-activating solutions. Shortening in Ca2+-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. PMID:26037312

  5. Force field development and simulations of senior dialkyl sulfoxides.

    PubMed

    Chaban, Vitaly V

    2016-04-21

    Thermodynamics, structure, and dynamics of diethyl sulfoxide (DESO) and ethyl methyl sulfoxide (EMSO) were investigated using ab initio calculations and non-polarizable potential based molecular dynamics (MD) simulations. The additive pairwise force field (FF) for EMSO and DESO was proposed for the first time, preserving explicit compatibility with their most known homologue, DMSO. The simulations reveal similar structures and thermodynamic properties of DMSO, DESO and EMSO. However, the transport properties are significantly different: DESO and DMSO are less mobile and an order of magnitude more viscous. Furthermore, dipole reorientation in DESO and EMSO occurs ca. 2-4 times slower than in DMSO at room temperature. This observation favors applications of higher sulfoxides as cryoprotectants and provides a microscopic interpretation of the earlier experimental data. PMID:27031577

  6. 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

  7. [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. PMID:27120950

  8. Development of a Computational Elbow Model with Experimental Validation of Kinematics and Muscle Forces.

    PubMed

    Kusins, Jonathan R; Willing, Ryan; King, Graham J; Ferreira, Louis M

    2016-08-01

    A computational elbow joint model was developed with a main goal of providing complimentary data to experimental results. The computational model was developed and validated using an experimental elbow joint phantom consisting of a linked total joint replacement. An established in-vitro motion simulator was used to actively flex/extend the experimental elbow in multiple orientations. Muscle forces predicted by the computational model were similar to the experimental model in 4 out of the 5 orientations with errors less than 7.5 N. Valgus angle kinematics were in agreement with differences less than 2.3°. In addition, changes in radial head length, a clinically relevant condition following elbow reconstruction, were simulated in both models and compared. Both lengthening and shortening of the radial head prosthesis altered muscle forces by less than 3.5 N in both models, and valgus angles agreed within 1°. The computational model proved valuable in cross validation with the experimental model, elucidating important limitations in the in-vitro motion simulator's controller. With continued development, the computational model can be a complimentary tool to experimental studies by providing additional noninvasive outcome measurements. PMID:26957523

  9. 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

  10. 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

  11. Horse chestnut extract induces contraction force generation in fibroblasts through activation of Rho/Rho kinase.

    PubMed

    Fujimura, Tsutomu; Moriwaki, Shigeru; Hotta, Mitsuyuki; Kitahara, Takashi; Takema, Yoshinori

    2006-06-01

    Contraction forces generated by non-muscle cells such as fibroblasts play important roles in determining cell morphology, vasoconstriction, and/or wound healing. However, few factors that induce cell contraction forces are known, such as lysophosphatidic acid and thrombin. Our study analyzed various plant extracts for ingredients that induce generation of cell contraction forces in fibroblasts populating collagen gels. We found that an extract of Horse chestnut (Aesculus hippocastanum) is able to induce such contraction forces in fibroblasts. The involvement of actin polymerization and stress fiber formation in the force generation was suggested by inhibition of this effect by cytochalasin D and by Rhodamine phalloidin. Rho kinase inhibitors (Y27632 and HA1077) and a Rho inhibitor (exoenzyme C3) significantly inhibited the force generation induced by the Horse chestnut extract. H7, which inhibits Rho kinase as well as other protein kinases, also significantly inhibited induction of force generation. However, inhibitors of other protein kinases such as myosin light chain kinase (ML-9), protein kinase C (Calphostin), protein kinase A (KT5720), and tyrosine kinase (Genistein, Herbimycin A) had no effect on force generation induced by Horse chestnut extract. These results suggest that the Horse chestnut extract induces generation of contraction forces in fibroblasts through stress fiber formation followed by activation of Rho protein and Rho kinase but not myosin light chain kinase or other protein kinases. PMID:16754996

  12. A system for the determination of planar force vectors from spontaneously active chicken embryos.

    PubMed

    Sharp, Andrew A; Cain, Blake W; Pakiraih, Joanna; Williams, James L

    2014-11-01

    Generally, a combination of kinematic, electromyographic (EMG), and force measurements are used to understand how an organism generates and controls movement. The chicken embryo has been a very useful model system for understanding the early stages of embryonic motility in vertebrates. Unfortunately, the size and delicate nature of embryos makes studies of motility during embryogenesis very challenging. Both kinematic and EMG recordings have been achieved in embryonic chickens, but two-dimensional force vector recordings have not. Here, we describe a dual-axis system for measuring force generated by the leg of embryonic chickens. The system employs two strain gauges to measure planar forces oriented with the plane of motion of the leg. This system responds to forces according to the principles of Pythagorean geometry, which allows a simple computational program to determine the force vector (magnitude and direction) generated during spontaneous motor activity. The system is able to determine force vectors for forces >0.5 mN accurately and allows for simultaneous kinematic and EMG recordings. This sensitivity is sufficient for force vector measurements encompassing most embryonic leg movements in midstage chicken embryos allowing for a more complete understanding of embryonic motility. Variations on this system are discussed to enable nonideal or alternative sensor arrangements and to allow for translation of this approach to other delicate model systems. PMID:25143544

  13. FLAP (Force and Loads Analysis Program) code development and validation

    SciTech Connect

    Wright, A.D.; Buhl, M.L.; Thresher, R.W.

    1988-01-01

    The Force and Loads Analysis Program (FLAP) has been refined to include the teetering degree of freedom (without delta-3). This report describes these refinements, as well as comparisons of predicted blade-bending moments to tet measurements. Wind-tunnel data for a 1/20-scale model of the Boeing MOD-2 machine were used to compare FLAP predictions for the cyclic flap-bending moments at the 33% spanwise station for three different wind speeds. The comparisons were made for both rigid- and teetering-hub cases. The code was written in Fortran 77 to be especially useful on the IBM PC family of computers. A special effort was made to make the program ''user friendly'' and readable. This report can be used as a user's guide; it includes a program description, a method of preparing input files, and information on the correct method of executing the code. A method of correctly preparing blade input data from a structural-dynamics viewpoint is also described. The code and this report are now available for public use. 10 refs., 28 figs., 22 tabs.

  14. Force Feedback Controls Motor Activity and Mechanical Properties of Self-Assembling Branched Actin Networks.

    PubMed

    Bieling, Peter; Li, Tai-De; Weichsel, Julian; McGorty, Ryan; Jreij, Pamela; Huang, Bo; Fletcher, Daniel A; Mullins, R Dyche

    2016-01-14

    Branched actin networks--created by the Arp2/3 complex, capping protein, and a nucleation promoting factor--generate and transmit forces required for many cellular processes, but their response to force is poorly understood. To address this, we assembled branched actin networks in vitro from purified components and used simultaneous fluorescence and atomic force microscopy to quantify their molecular composition and material properties under various forces. Remarkably, mechanical loading of these self-assembling materials increases their density, power, and efficiency. Microscopically, increased density reflects increased filament number and altered geometry but no change in average length. Macroscopically, increased density enhances network stiffness and resistance to mechanical failure beyond those of isotropic actin networks. These effects endow branched actin networks with memory of their mechanical history that shapes their material properties and motor activity. This work reveals intrinsic force feedback mechanisms by which mechanical resistance makes self-assembling actin networks stiffer, stronger, and more powerful. PMID:26771487

  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. PMID:22720393

  16. 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…

  17. 78 FR 23970 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-23

    ... date for attending the meeting. Correction In the Federal Register of April 10, 2013, in FR Doc. 2013... 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...

  18. 75 FR 22497 - Interagency Task Force on Veterans Small Business Development

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-29

    ..., 2010. [FR Doc. 2010-10172 Filed 4-28-10; 8:45 am] Billing code 3195-W0-P ... 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...

  19. Regulation of force development studied by photolysis of caged ADP in rabbit skinned psoas fibers.

    PubMed

    Lu, Z; Swartz, D R; Metzger, J M; Moss, R L; Walker, J W

    2001-07-01

    The present study examined the effects of Ca(2+) and strongly bound cross-bridges on tension development induced by changes in the concentration of MgADP. Addition of MgADP to the bath increased isometric tension over a wide range of [Ca(2+)] in skinned fibers from rabbit psoas muscle. Tension-pCa (pCa is -log [Ca(2+)]) relationships and stiffness measurements indicated that MgADP increased mean force per cross-bridge at maximal Ca(2+) and increased recruitment of cross-bridges at submaximal Ca(2+). Photolysis of caged ADP to cause a 0.5 mM MgADP jump initiated an increase in isometric tension under all conditions examined, even at pCa 6.4 where there was no active tension before ADP release. Tension increased monophasically with an observed rate constant, k(ADP), which was similar in rate and Ca(2+) sensitivity to the rate constant of tension re-development, k(tr), measured in the same fibers by a release-re-stretch protocol. The amplitude of the caged ADP tension transient had a bell-shaped dependence on Ca(2+), reaching a maximum at intermediate Ca(2+) (pCa 6). The role of strong binding cross-bridges in the ADP response was tested by treatment of fibers with a strong binding derivative of myosin subfragment 1 (NEM-S1). In the presence of NEM-S1, the rate and amplitude of the caged ADP response were no longer sensitive to variations in the level of activator Ca(2+). The results are consistent with a model in which ADP-bound cross-bridges cooperatively activate the thin filament regulatory system at submaximal Ca(2+). This cooperative interaction influences both the magnitude and kinetics of force generation in skeletal muscle. PMID:11423418

  20. Computer keyswitch force-displacement characteristics affect muscle activity patterns during index finger tapping.

    PubMed

    Lee, David L; Kuo, Po-Ling; Jindrich, Devin L; Dennerlein, Jack T

    2009-10-01

    This study examined the effect of computer keyboard keyswitch design on muscle activity patterns during finger tapping. In a repeated-measures laboratory experiment, six participants tapped with their index fingers on five isolated keyswitch designs with varying force-displacement characteristics that provided pairwise comparisons for the design factors of (1) activation force (0.31 N vs. 0.59 N; 0.55 N vs. 0.93 N), (2) key travel (2.5mm vs. 3.5mm), and (3) shape of the force-displacement curve as realized through buckling-spring vs. rubber-dome switch designs. A load cell underneath the keyswitch measured vertical fingertip forces, and intramuscular fine wire EMG electrodes measured muscle activity patterns of two intrinsic (first lumbricalis, first dorsal interossei) and three extrinsic (flexor digitorum superficialis, flexor digitorum profundus, and extensor digitorum communis) index finger muscles. The amplitude of muscle activity for the first dorsal interossei increased 25.9% with larger activation forces, but not for the extrinsic muscles. The amplitude of muscle activity for the first lumbricalis and the duration of muscle activities for the first dorsal interossei and both extrinsic flexor muscles decreased up to 40.4% with longer key travel. The amplitude of muscle activity in the first dorsal interossei increased 36.6% and the duration of muscle activity for all muscles, except flexor digitorum profundus, decreased up to 49.1% with the buckling-spring design relative to the rubber-dome design. These findings suggest that simply changing the force-displacement characteristics of a keyswitch changes the dynamic loading of the muscles, especially in the intrinsic muscles, during keyboard work. PMID:18515146

  1. 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.

  2. Activity investigation of pinostrobin towards herpes simplex virus-1 as determined by atomic force microscopy.

    PubMed

    Wu, Nan; Kong, Yu; Zu, Yuangang; Fu, Yujie; Liu, Zhiguo; Meng, Ronghua; Liu, Xia; Efferth, Thomas

    2011-01-15

    In the present study, the antiviral activity of pinostrobin towards herpes simplex virus-1 (HSV-1) was investigated by MTT assay and atomic force microscopy. Pinostrobin can inhibit HSV-1 replication with 50% effective concentration (EC(50)) of 22.71 ± 1.72 μg/ml. MTT assay showed HSV-1 was significantly inhibited when pretreated with pinostrobin, with the inhibition of 85.69 ± 2.59%. Significant changes in morphology and size of HSV-1 were observed by atomic force microscopy (AFM) in response to pinostrobin treatment. AFM topography and phase images showed that with increasing time, the envelope was shedded and damaged, finally leading to virus inactivation. With increasing concentration, pinostrobin caused a gradual leakage, also contributing to breakage of the envelope and virus inactivation. Treatment effect of oral pinostrobin in vivo showed that pinostrobin (50mg/kg/dose) possesses definite therapeutical effect in the development of lesion score. In general, the results showed that AFM represents a powerful technique for the investigation of morphology and size of HSV-1 treated by antiviral agents. AFM is applicable to study chemically induced morphological changes at the nanometer level. PMID:20739162

  3. Augmented force output in skeletal muscle fibres of Xenopus following a preceding bout of activity.

    PubMed Central

    Bruton, J D; Westerblad, H; Katz, A; Lännergren, J

    1996-01-01

    1. The effect of a brief period of activity on subsequent isometric tetanic force production was investigated in single muscle fibres of Xenopus laevis. 2. Following a train of ten tetani separated by 4 s intervals, tetanic force was significantly augmented by about 10%. The tetanic force augmentation persisted for at least 15 min and then slowly subsided. A similar potentiation was seen following trains of five and twenty tetani. 3. During the period of tetanic force potentiation, tetanic calcium was reduced by more than 30%, and intracellular pH was reduced from 7.15 +/- 0.07 to 7.03 +/- 0.11 (n = 4). 4. Fibre swelling was greatest at 1 min and then subsided over 15-20 min and possibly accounted for a small part of the observed force potentiation. 5. A reduction in the inorganic phosphate (P1) concentration of more than 40% was found in fibres frozen in liquid nitrogen at the peak of force potentiation compared with resting fibres. 6. It is concluded that the augmentation of tetanic force found after a brief preceding bout of activity is due to a reduction in inorganic phosphate. This mechanism may underlie the improved performance observed in athletes after warm-up. Images Figure 2 PMID:8735706

  4. 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.

  5. Force Field Development and Molecular Dynamics of [NiFe] Hydrogenase

    SciTech Connect

    Smith, Dayle MA; Xiong, Yijia; Straatsma, TP; Rosso, Kevin M.; Squier, Thomas C.

    2012-05-09

    Classical molecular force-field parameters describing the structure and motion of metal clusters in [NiFe] hydrogenase enzymes can be used to compare the dynamics and thermodynamics of [NiFe] under different oxidation, protonation, and ligation circumstances. Using density functional theory (DFT) calculations of small model clusters representative of the active site and the proximal, medial, and distal Fe/S metal centers and their attached protein side chains, we have calculated classical force-field parameters for [NiFe] in reduced and oxidized states, including internal coordinates, force constants, and atom-centered charges. Derived force constants revealed that cysteinate ligands bound to the metal ions are more flexible in the Ni-B active site, which has a bridging hydroxide ligand, than in the Ni-C active site, which has a bridging hydride. Ten nanosecond all-atom, explicit-solvent MD simulations of [NiFe] hydrogenase in oxidized and reduced catalytic states established the stability of the derived force-field parameters in terms of C{alpha} and metal cluster fluctuations. Average active site structures from the protein MD simulations are consistent with [NiFe] structures from the Protein Data Bank, suggesting that the derived force-field parameters are transferrable to other hydrogenases beyond the structure used for testing. A comparison of experimental H{sub 2}-production rates demonstrated a relationship between cysteinate side chain rotation and activity, justifying the use of a fully dynamic model of [NiFe] metal cluster motion.

  6. 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.

  7. 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. PMID:26091619

  8. Evaluating Results of Economic and Work Force Development Programs.

    ERIC Educational Resources Information Center

    Alfred, Richard L.

    1991-01-01

    Addresses issues related to the evaluation of community colleges' economic development efforts, describing the context for evaluation in terms of the external environment and college management/governance; practical realities guiding evaluation; steps in designing an evaluation programs; and the application of results to decision making. (DMM)

  9. 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…

  10. Citizen Engagement: Driving Force of E-Society Development

    NASA Astrophysics Data System (ADS)

    Qiu, Xiaolin

    Starting from the belief that e-inclusion should be the strategic choice, and full engagement of every citizen is the key to the success and healthy development of e-society, this paper puts forward that "Information Commons" model can be applied to a larger target group: the disadvantaged citizens for their information rights and e-literacy education. Three IC applications: residents' community IC, public library IC, and government agency IC are discussed.

  11. 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.

  12. Rate of Force Development in the Handgripping Muscles by Females as a Function of Fatigue Level.

    ERIC Educational Resources Information Center

    Ewing, John L., Jr.; Stull, G. Alan

    1984-01-01

    This study determined the effects on the rate at which the handgripping muscles in college-age females develop force when they are fatigued to 80, 60, and 40 percent of their original maximal strength level. (JMK)

  13. Effects of forward head posture on forced vital capacity and respiratory muscles activity.

    PubMed

    Han, Jintae; Park, Soojin; Kim, Youngju; Choi, Yeonsung; Lyu, Hyeonnam

    2016-01-01

    [Purpose] This study investigated the effects of forward head posture on forced vital capacity and deep breathing. [Subjects] Twenty-six subjects, divided into the two groups (normal and forward head posture groups), participated in this study. [Methods] Forced vital capacity and forced expiratory volume in 1 second were measured using respiratory function instrumentation that met the American Thoracic Society's recommendation for diagnostic spirometry. Accessory respiratory muscle activity during deep breathing was measured by electromyography. A Mann-Whitney test was used to compare the measure variables between the normal and forward head posture group. [Results] Forced vital capacity and forced expiratory volume in 1 second were significantly lower in the forward head posture group than in the normal group. Accessory respiratory muscle activity was also lower in the forward head posture group than in the normal group. In particular, the sternocleidomastoid and pectoralis major activity of the forward head posture group was significantly lower than that of normal group. Activities of the other muscles were generally decreased with forward head posture, but were not significantly different between the two groups. [Conclusion] These results indicate that forward head posture could reduce vital capacity, possibly because of weakness or disharmony of the accessory respiratory muscles. PMID:26957743

  14. On Frictional Forces between the Finger and a Textured Surface during Active Touch.

    PubMed

    Janko, Marco; Primerano, Richard; Visell, Yon

    2016-01-01

    We investigated forces felt by a bare finger in sliding contact with a textured surface, and how they depend on properties of the surface and contact interaction. Prior research has shed light on haptic texture perception. Nevertheless, how texture-produced forces depend on the properties of a touched object or the way that it is touched is less clear. To address this, we designed an apparatus to accurately measure contact forces between a sliding finger and a textured surface. We fabricated textured surfaces, and measured spatial variations in forces produced as subjects explored the surfaces with a bare finger. We analyzed variations in these force signals, and their dependence on object geometry and contact parameters. We observed a number of phenomena, including transient stick-slip behavior, nonlinearities, phase variations, and large force fluctuations, in the form of aperiodic signal components that proved difficult to model for fine surfaces. Moreover, metrics such as total harmonic distortion and normalized variance decreased as the spatial scale of the stimuli increased. The results of this study suggest that surface geometry and contact parameters are insufficient to account for force production during such interactions. Moreover, the results shed light on perceptual challenges solved by the haptic system during active touch sensing of surface texture. PMID:26685262

  15. Development of "active correlation" technique

    NASA Astrophysics Data System (ADS)

    Tsyganov, Yu. S.

    2016-01-01

    With reaching to extremely high intensities of heavy-ion beams new requirements for the detection system of the Dubna Gas-Filled Recoil Separator (DGFRS) will definitely be set. One of the challenges is how to apply the "active correlations" method to suppress beam associated background products without significant losses in the whole long-term experiment efficiency value. Different scenarios and equations to develop the method according this requirement are under consideration in the present paper. The execution time to estimate the dead time parameter associated with the optimal choice of the life-time parameter is presented.

  16. Critical speeds and forced response solutions for active magnetic bearing turbomachinery, part 1

    NASA Technical Reports Server (NTRS)

    Keesee, J.; Rawal, D.; Kirk, R. Gordon

    1991-01-01

    The prediction of critical speeds and forced response of active magnetic bearing turbomachinery is of great interest due to the increased use of this new and promising technology. Calculating the system undamped critical speeds and forced response is important to all those who are involved in the design of the active magnetic bearing system. An extended Jeffcott model which was used as an approximate solution to a more accurate transfer matrix procedure is presented. Theory behind a two-degree-of freedom extended Jeffcoat model is presented. Results of the natural frequency calculation are shown followed by the results of the forced response calculation. The system response was predicted for two types of forcing. A constant magnitude excitation with a wide frequency variation was applied at the bearings as one forcing function. The normal unbalance force at the midspan was the second source of excitation. The results of this extended Jeffcott solution gives useful design guidance for the influence of the first and third modes of a symmetric rotor system.

  17. 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.

  18. The effect of acoustic forcing on trailing edge separation and near wake development of an airfoil

    NASA Technical Reports Server (NTRS)

    Huang, L. S.; Bryant, T. D.; Maestrello, L.

    1988-01-01

    An experimental study was conducted to investigate the effect of acoustic forcing on flow fields near the trailing edge of a symmetric airfoil at zero angle of attack. At low chord Reynolds numbers, the boundary layers separate from the surfaces in the rear part of the airfoil and create recirculation regions near the trailing edge. It is shown that with the introduction of acoustic forcing through a slot in the vicinity of the separation point, periodic large-scale structures are generated in the trailing edge region. Significant reduction of trailing edge separation is achieved. It is also found that the most effective forcing frequency to control trailing edge separation is the wake vortex shedding frequency. As a result of forcing, applied only on the upper surface, the upper boundary layer is accelerated and the flow over the lower surface decelerated. Consequently, an asymmetric wake is formed. The results presented indicate that the development of the near wake varies with forcing conditions.

  19. 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.

  20. 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.

  1. A force-activated trip switch triggers rapid dissociation of a colicin from its immunity protein.

    PubMed

    Farrance, Oliver E; Hann, Eleanore; Kaminska, Renata; Housden, Nicholas G; Derrington, Sasha R; Kleanthous, Colin; Radford, Sheena E; Brockwell, David J

    2013-01-01

    Colicins are protein antibiotics synthesised by Escherichia coli strains to target and kill related bacteria. To prevent host suicide, colicins are inactivated by binding to immunity proteins. Despite their high avidity (K(d) ≈ fM, lifetime ≈ 4 days), immunity protein release is a pre-requisite of colicin intoxication, which occurs on a timescale of minutes. Here, by measuring the dynamic force spectrum of the dissociation of the DNase domain of colicin E9 (E9) and immunity protein 9 (Im9) complex using an atomic force microscope we show that application of low forces (<20 pN) increases the rate of complex dissociation 10(6)-fold, to a timescale (lifetime ≈ 10 ms) compatible with intoxication. We term this catastrophic force-triggered increase in off-rate a trip bond. Using mutational analysis, we elucidate the mechanism of this switch in affinity. We show that the N-terminal region of E9, which has sparse contacts with the hydrophobic core, is linked to an allosteric activator region in E9 (residues 21-30) whose remodelling triggers immunity protein release. Diversion of the force transduction pathway by the introduction of appropriately positioned disulfide bridges yields a force resistant complex with a lifetime identical to that measured by ensemble techniques. A trip switch within E9 is ideal for its function as it allows bipartite complex affinity, whereby the stable colicin:immunity protein complex required for host protection can be readily converted to a kinetically unstable complex whose dissociation is necessary for cellular invasion and competitor death. More generally, the observation of two force phenotypes for the E9:Im9 complex demonstrates that force can re-sculpt the underlying energy landscape, providing new opportunities to modulate biological reactions in vivo; this rationalises the commonly observed discrepancy between off-rates measured by dynamic force spectroscopy and ensemble methods. PMID:23431269

  2. Development of measuring system to measure standing pose of the foot using distributed triaxial force sensor.

    PubMed

    Nishi, Akimi; Tanaka, Noriko; Tsujiuchi, Nobutaka; Koizumi, Takayuki; Oshima, Hiroko; Minato, Kotaro; Yoshida, Masaki; Tsuchiya, Yotaro

    2006-01-01

    The bottom of a person's foot grips the floor for balance, and the action force and action moment work at the foot bottom when he maintains posture and when he moves. They are important indices in the evaluation and the medical attention of standing pose balance and gait disturbances. A lot of equipments to measure the floor reaction force have been researched. However, no floor reaction force meter exists that can measure distribution information force in three directions. This paper aims at the development of a system that can measure the standing pose of the foot that exists from a measuring instrument and that can measure the standing pose of foot distributed 6times4 three axis force sensors and software that displays and preserves the output of the sensor element. A time change of force that worked at the foot bottom is sought as a vector by outputting each sensor element. Moreover, an action vector is three dimensionally displayed whose data can be intuitively understood. The results of experiments show that the measuring system can measure the action force of the foot bottom as distribution information on force in three directions. PMID:17945646

  3. Coherence of EMG activity and single motor unit discharge patterns in human rhythmical force production.

    PubMed

    Sosnoff, Jacob J; Vaillancourt, David E; Larsson, Lars; Newell, Karl M

    2005-03-30

    The purpose of this study was to examine the modulation of the motor neuronal pool as a function of task dynamics. Specifically, we investigated the effects of task frequency on the single motor unit discharge pattern, electromyogram (EMG) activity and effector force output. Myoelectric activity and effector force were recorded while young adults isometrically abducted their first dorsal interosseus at five sinusoidal targets (0.5 Hz, 1 Hz, 2 Hz, 3 Hz and 4 Hz) and at two force levels (5% and 25% maximum voluntary contraction (MVC)). Individual motor unit spike trains were isolated from the EMG. Auto-spectral and coherence analyses were performed on the force output, EMG and motor unit spike trains. The frequency of maximal coherence between the EMG and force output closely corresponded to the target frequency in all conditions. There was a broadband distribution of power with multiple peaks in the EMG and motor unit spectrums in the 0.5 Hz and 1 Hz targets. However, the EMG and motor unit spectrums in the 2 Hz, 3 Hz and 4 Hz targets were characterized by an increasingly narrower band of activity with one dominant peak that closely corresponded to the target. There is high coherence between EMG output and target force frequency, but the relative contribution of the fast and slow neuromuscular bands are differentially influenced by the task frequency. The rhythmical organization of neuromuscular output in the 0.5 Hz task is relatively broadband and similar to that shown previously for constant level force output. The frequency structure of neuromuscular organization becomes increasingly more narrowband as the frequency of the target increases (2-4 Hz). The modulation of the motor neuronal pool is adaptive and depends on the relative contribution of feedback and feedforward control processes, which are driven by the task demands. PMID:15698897

  4. 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…

  5. Tremor irregularity, torque steadiness and rate of force development in Parkinson's disease.

    PubMed

    Rose, Martin H; Løkkegaard, Annemette; Sonne-Holm, Stig; Jensen, Bente R

    2013-04-01

    We investigated lower-extremity isometric tremor Approximate Entropy (irregularity), torque steadiness and rate of force development (RFD) and their associations to muscle activation strategy during isometric knee extensions in patients with Parkinson's disease (PD). Thirteen male patients with idiopathic PD and 15 neurologically healthy matched controls performed isometric maximal contractions (extension/flexion) as well as steady submaximal and powerful isometric knee extensions. The patients with PD showed decreased isometric tremor irregularity. Torque steadiness was reduced in PD and the patients had increased muscle coactivation. A markedly lower RFD was found in PD and the decreased RFD correlated with reduced agonist muscle activation. Furthermore, patient RFD correlated with the Movement-Disorder-Society-Unified-Parkinson's-Disease-Rating-Scale 3 (motor part) scores. We concluded that both knee isometric tremor Approximate Entropy and torque steadiness clearly differentiate between patients with PD and healthy controls. Furthermore, severely compromised RFD was found in patients with PD and was associated with decreased agonist muscle activation. PMID:23155115

  6. Developing ab initio quality force fields from condensed phase quantum-mechanics/molecular-mechanics calculations through the adaptive force matching method

    NASA Astrophysics Data System (ADS)

    Akin-Ojo, Omololu; Song, Yang; Wang, Feng

    2008-08-01

    A new method called adaptive force matching (AFM) has been developed that is capable of producing high quality force fields for condensed phase simulations. This procedure involves the parametrization of force fields to reproduce ab initio forces obtained from condensed phase quantum-mechanics/molecular-mechanics (QM/MM) calculations. During the procedure, the MM part of the QM/MM is iteratively improved so as to approach ab initio quality. In this work, the AFM method has been tested to parametrize force fields for liquid water so that the resulting force fields reproduce forces calculated using the ab initio MP2 and the Kohn-Sham density functional theory with the Becke-Lee-Yang-Parr (BLYP) and Becke three-parameter LYP (B3LYP) exchange correlation functionals. The AFM force fields generated in this work are very simple to evaluate and are supported by most molecular dynamics (MD) codes. At the same time, the quality of the forces predicted by the AFM force fields rivals that of very expensive ab initio calculations and are found to successfully reproduce many experimental properties. The site-site radial distribution functions (RDFs) obtained from MD simulations using the force field generated from the BLYP functional through AFM compare favorably with the previously published RDFs from Car-Parrinello MD simulations with the same functional. Technical aspects of AFM such as the optimal QM cluster size, optimal basis set, and optimal QM method to be used with the AFM procedure are discussed in this paper.

  7. Development of a boxing dynamometer and its punch force discrimination efficacy.

    PubMed

    Smith, M S; Dyson, R J; Hale, T; Janaway, L

    2000-06-01

    The development of sport-specific dynamometers is an important step towards ecological validity in analysing athlete performance. Design limitations in previous punch-measuring devices have resulted in values which may not or cannot fully reflect the force and multidirectional components in a punch. In developing this boxing dynamometer, a triaxial force measurement system and a boxing manikin interface were combined. The repeatability and accuracy of the dynamomoter were assessed using simulated straight punches. Discrimination efficacy was assessed by comparison of the maximal punching force of seven elite, eight intermediate and eight novice boxers during simulated boxing, throwing straight punches. For the elite, intermediate and novice groups, respectively, the maximal straight punching forces (mean +/- s(mean)) were 4800 +/- 227 N, 3722 +/- 133 N and 2381 +/- 116 N for the rear hand, and 2847 +/- 225 N, 2283 +/- 126 N and 1604 +/- 97 N for the lead hand. For all groups, maximal forces were larger for the rear than the lead hand (P < 0.001). Maximal punching force was greater in the elite than the intermediate group, and greater in the intermediate than the novice group (P < 0.05). The boxing dynamometer discriminated effectively between punching performance at three standards of performance and between the punching force of the rear and lead hands. PMID:10902679

  8. Deletion of the titin N2B region accelerates myofibrillar force development but does not alter relaxation kinetics.

    PubMed

    Elhamine, Fatiha; Radke, Michael H; Pfitzer, Gabriele; Granzier, Henk; Gotthardt, Michael; Stehle, Robert

    2014-09-01

    Cardiac titin is the main determinant of sarcomere stiffness during diastolic relaxation. To explore whether titin stiffness affects the kinetics of cardiac myofibrillar contraction and relaxation, we used subcellular myofibrils from the left ventricles of homozygous and heterozygous N2B-knockout mice which express truncated cardiac titins lacking the unique elastic N2B region. Compared with myofibrils from wild-type mice, myofibrils from knockout and heterozygous mice exhibit increased passive myofibrillar stiffness. To determine the kinetics of Ca(2+)-induced force development (rate constant kACT), myofibrils from knockout, heterozygous and wild-type mice were stretched to the same sarcomere length (2.3 µm) and rapidly activated with Ca(2+). Additionally, mechanically induced force-redevelopment kinetics (rate constant kTR) were determined by slackening and re-stretching myofibrils during Ca(2+)-mediated activation. Myofibrils from knockout mice exhibited significantly higher kACT, kTR and maximum Ca(2+)-activated tension than myofibrils from wild-type mice. By contrast, the kinetic parameters of biphasic force relaxation induced by rapidly reducing [Ca(2+)] were not significantly different among the three genotypes. These results indicate that increased titin stiffness promotes myocardial contraction by accelerating the formation of force-generating cross-bridges without decelerating relaxation. PMID:24982444

  9. Deletion of the titin N2B region accelerates myofibrillar force development but does not alter relaxation kinetics

    PubMed Central

    Elhamine, Fatiha; Radke, Michael H.; Pfitzer, Gabriele; Granzier, Henk; Gotthardt, Michael; Stehle, Robert

    2014-01-01

    ABSTRACT Cardiac titin is the main determinant of sarcomere stiffness during diastolic relaxation. To explore whether titin stiffness affects the kinetics of cardiac myofibrillar contraction and relaxation, we used subcellular myofibrils from the left ventricles of homozygous and heterozygous N2B-knockout mice which express truncated cardiac titins lacking the unique elastic N2B region. Compared with myofibrils from wild-type mice, myofibrils from knockout and heterozygous mice exhibit increased passive myofibrillar stiffness. To determine the kinetics of Ca2+-induced force development (rate constant kACT), myofibrils from knockout, heterozygous and wild-type mice were stretched to the same sarcomere length (2.3 µm) and rapidly activated with Ca2+. Additionally, mechanically induced force-redevelopment kinetics (rate constant kTR) were determined by slackening and re-stretching myofibrils during Ca2+-mediated activation. Myofibrils from knockout mice exhibited significantly higher kACT, kTR and maximum Ca2+-activated tension than myofibrils from wild-type mice. By contrast, the kinetic parameters of biphasic force relaxation induced by rapidly reducing [Ca2+] were not significantly different among the three genotypes. These results indicate that increased titin stiffness promotes myocardial contraction by accelerating the formation of force-generating cross-bridges without decelerating relaxation. PMID:24982444

  10. 'Hybrid-PLEMO', rehabilitation system for upper limbs with active / passive force feedback mode.

    PubMed

    Kikuchi, Takehito; Jin, Ying; Fukushima, Kazuki; Akai, Hiroki; Furusho, Junji

    2008-01-01

    Several rehabilitation robots for upper limbs have been proposed so far, and clinical effectiveness was reported in several studies for the aged people or patients with stroke. However most of them have only 2-DOF for its active motion. It is important for designing a rehabilitation system which trains in the 3-DOF space because the upper limbs of humans works in 3-DOF space even expect for the wrist. We developed the quasi 3-DOF rehabilitation system which has 2-DOF force-feedback function in working plane but its working plane can be adjusted the inclination. And we named it Hybrid-PLEMO for it can be switched between active type and passive type. Hybrid-PLEMO is a compact, low-cost rehabilitation system for upper limbs with high safety by using ER brakes or ER actuators. Additionally, in Hybrid-PLEMO, we take direct-drive linkage mechanism by adding sub links. In this paper, we describe the mechanism and haptic control of Hybrid-PLEMO. PMID:19163078

  11. Local sources of global climate forcing from different categories of land use activities

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Identifying and quantifying the sources of climate impacts from land use and land cover change (LULCC) is necessary to optimize policies regarding LULCC for climate change mitigation. These climate impacts are typically defined relative to emissions of CO2, or sometimes emissions of other long-lived greenhouse gases. Here we use previously published estimates of the radiative forcing (RF) of LULCC that include the short-lived forcing agents O3 and aerosols, in addition to long-lived greenhouse gases and land albedo change, for six projections of LULCC as a metric for quantifying climate impacts. The LULCC RF is attributed to three categories of LULCC activities: direct modifications to land cover, agriculture, and wildfire response, and sources of the forcing are ascribed to individual grid points for each sector. Results for the year 2010 show substantial positive forcings from the direct modifications and agriculture sectors, particularly from India, China, and southeast Asia, and a smaller magnitude negative forcing response from wildfires. The RF from direct modifications, mainly deforestation activities, exhibits a large range in future outcomes for the standard future scenarios implying that these activities, and not agricultural emissions (which lead to more consistent RFs between scenarios), will drive the LULCC RF in the future. We show that future forest area change can be used as a predictor of the future RF from direct modification activities, especially in the tropics, suggesting that deforestation-prevention policies that value land based on its C-content may be particularly effective at mitigating climate forcing originating in the tropics from this sector. Although, the response of wildfire RF to tropical land cover changes is not as easily scalable and yet imposes a non-trivial feedback onto the total LULCC RF.

  12. 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

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

    DOE PAGESBeta

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

    2016-04-26

    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 themore » active stresses and elasticity of the system. Finally, 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.« less

  14. 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.

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

    PubMed

    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

  16. Cortical Activity during a Highly-Trained Resistance Exercise Movement Emphasizing Force, Power or Volume

    PubMed Central

    Flanagan, Shawn D.; Dunn-Lewis, Courtenay; Comstock, Brett A.; Maresh, Carl M.; Volek, Jeff S.; Denegar, Craig R.; Kraemer, William J.

    2012-01-01

    Cortical activity is thought to reflect the biomechanical properties of movement (e.g., force or velocity of movement), but fatigue and movement familiarity are important factors that require additional consideration in electrophysiological research. The purpose of this within-group quantitative electroencephalogram (EEG) investigation was to examine changes in cortical activity amplitude and location during four resistance exercise movement protocols emphasizing rate (PWR), magnitude (FOR), or volume (VOL) of force production, while accounting for movement familiarity and fatigue. EEG signals were recorded during each complete repetition and were then grouped by functional region, processed to eliminate artifacts, and averaged to compare overall differences in the magnitude and location of cortical activity between protocols over the course of six sets. Biomechanical, biochemical, and exertional data were collected to contextualize electrophysiological data. The most fatiguing protocols were accompanied by the greatest increases in cortical activity. Furthermore, despite non-incremental loading and lower force levels, VOL displayed the largest increases in cortical activity over time and greatest motor and sensory activity overall. Our findings suggest that cortical activity is strongly related to aspects of fatigue during a high intensity resistance exercise movement. PMID:24961265

  17. 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…

  18. Gravitational force modulates muscle activity during mechanical oscillation of the tibia in humans

    PubMed Central

    Chang, Shuo-Hsiu; Dudley-Javoroski, Shauna; Shields, Richard K.

    2012-01-01

    Mechanical oscillation (vibration) is an osteogenic stimulus for bone in animal models and may hold promise as an anti-osteoporosis measure in humans with spinal cord injury (SCI). However, the level of reflex induced muscle contractions associated with various loads (g force) during limb segment oscillation is uncertain. The purpose of this study was to determine whether certain gravitational loads (g forces) at a fixed oscillation frequency (30 Hz) increases muscle reflex activity in individuals with and without SCI. Nine healthy subjects and two individuals with SCI sat with their hip and knee joints at 90° and the foot secured on an oscillation platform. Vertical mechanical oscillations were introduced at 0.3, 0.6, 1.2, 3 and 5g force for 20 seconds at 30 Hz. Non-SCI subjects received the oscillation with and without a 5% MVC background contraction. Peak soleus and tibialis anterior (TA) EMG were normalized to M-max. Soleus and TA EMG were < 2.5% of M-max in both SCI and non-SCI subjects. The greatest EMG occurred at the highest acceleration (5g). Low magnitude mechanical oscillation, shown to enhance bone anabolism in animal models, did not elicit high levels of reflex muscle activity in individuals with and without SCI. These findings support the g force modulated background muscle activity during fixed frequency vibration. The magnitude of muscle activity was low and likely does not influence the load during fixed frequency oscillation of the tibia. PMID:21708472

  19. Resonant passive-active vibration absorber with integrated force feedback control

    NASA Astrophysics Data System (ADS)

    Høgsberg, Jan; Brodersen, Mark L.; Krenk, Steen

    2016-04-01

    A general format of a two-terminal vibration absorber is constructed by placing a passive unit in series with a hybrid unit, composed of an active actuator in parallel with a second passive element. The displacement of the active actuator is controlled by an integrated feedback control with the difference in force between the two passive elements as input. This format allows passive and active contributions to be combined arbitrarily within the hybrid unit, which results in a versatile absorber format with guaranteed closed-loop stability. This is demonstrated for resonant absorbers with inertia realized passively by a mechanical inerter or actively by the integrated force feedback. Accurate calibration formulae are presented for two particular absorber configurations and the performance is subsequently demonstrated with respect to both equal modal damping and effective response reduction.

  20. 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.

  1. 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. PMID:26276984

  2. 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.

  3. Binding activity of patterned concanavalin A studied by atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Lebed, Kateryna; Pyka-Fosciak, Grazyna; Raczkowska, Joanna; Lekka, Malgorzata; Styczen, Jan

    2005-05-01

    The mode of protein immobilization plays a crucial role in the preparation of protein microarrays used for a wide spectrum of applications in analytical biochemistry. The microcontact printing technique was used to form a protein pattern using concanavalin A (Con A) since Con A belongs to a group of proteins widely used in analytical assays due to their selectivity as regards different kinds of carbohydrates. Atomic force microscopy was used to image surface topography, delivering information about the quality of the protein pattern. The force spectroscopy mode was used to verify the functional activity of deposited proteins via determination of the forces of interaction between Con A and carboxypeptidase Y bearing carbohydrate structure recognized by Con A. The calculated binding force between Con A and CaY was 105 ± 2 pN and it was compared with that measured for Con A deposited directly from the protein solution. The similarity of the value obtained for the interaction force was independent of the mode of protein deposition, thereby verifying that the microcontact printing technique did not influence the carbohydrate binding activity of Con A. The correlation between the surface topography of patterned samples and adhesion maps obtained showed the possible use of AFM for studying the chemical properties of different regions of the micropatterns produced.

  4. [Prospective planning of activity of the Medical service of the Armed Forces of the Russian Federation for 2016-2020].

    PubMed

    Fisun, A Ya; Kalachev, O V; Redkin, E E; Bershev, M A; Murzo, A V

    2016-04-01

    The article reflects the characteristics of the Plan of activities of the Ministry of Defence of the Russian Federation for 2016-2020--an important long-term planning document of the Armed Forces. It stressed the need for synchronization of activities for chain of command and deadline. Presented structure of the Medical Service Plan Military District operations (fleet) military medical organization. The attention is focused on the content of its sections. For example, a military hospital layouts presented an action plan and a schedule of events. Reflecting the requirements of the Minister of Defense for the development and adjustment plans, indicators of their performance. PMID:27416714

  5. 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. PMID:26823341

  6. Development of living cell force sensors for the interrogation of cell surface interactions

    NASA Astrophysics Data System (ADS)

    Brown, Scott Chang

    The measurement of cell surface interactions, or cell interaction forces, are critical for the early diagnosis and prevention of disease, the design of targeted drug and gene delivery vehicles, the development of next-generation implant materials, and much more. However, the technologies and devices that are currently available are highly limited with respect to the dynamic force range over which they can measure cell-cell or cell-substratum interactions, and with their ability to adequately mimic biologically relevant systems. Consequently, research efforts that involve cell surface interactions have been limited. In this dissertation, existing tools for research at the nanoscale (i.e., atomic force microscopy microcantilevers) are modified to develop living cell force sensors that allow for the highly sensitive measurement of cell-mediated interactions over the entire range of forces expected in biotechnology (and nano-biotechnology) research (from a single to millions of receptor-ligand bonds). Several force sensor motifs have been developed that can be used to measure interactions using single adherent cells, single suspension culture cell, and cell monolayers (tissues) over a wide range of interaction conditions (e.g., approach velocity, shear rate, contact time) using a conventional atomic force microscope. This new tool has been applied to study the pathogenesis of spontaneous pneumothorax and the interaction of cells with 14 man-made interfaces. Consequently, a new hypothesis of the interactions that manifest spontaneous pneumothorax has been developed. Additionally, these findings have the potential to lead to the development of tools for data mining materials and surfaces for unique cell interactions that could have an immense societal impact.

  7. An active optimal control strategy of rotor vibrations using external forces

    NASA Technical Reports Server (NTRS)

    Zhu, W.; Castelazo, I.; Nelson, H. D.

    1989-01-01

    An active control strategy for lateral rotor vibrations using external forces is proposed. An extended state observer is used to reconstruct the full states and the unbalance distribution. An optimal controller which accommodates persistent unbalance excitation is derived with feedback of estimated states and unbalances. Numerical simulations were conducted for two separate four degree of freedom rotor systems. These simulations indicated that the proposed strategy can achieve almost complete vibration cancellation. This was shown to be true even when the number of external control forces was less than the system order so long as coordinate coupling was present. Both steady state and transient response at a constant speed are presented.

  8. 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. PMID:26655224

  9. 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,…

  10. 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…

  11. Active control of sound fields in elastic cylinders by multi-control forces

    NASA Technical Reports Server (NTRS)

    Jones, J. D.; Fuller, C. R.

    1987-01-01

    An unstiffened cylindrical model was used to study the control of sound transmission into aircraft cabins by the use of multi-control forces applied directly to the cylinder wall. External acoustic monopoles were located on each side of the cylinder to approximate the propeller noise source. This allowed the study of a dual control system utilizing multi-control forces in conjunction with synchrophasing of the twin acoustic monopole sources. For acoustic resonant conditions within the cavity, a spatially averaged noise reduction of approximately 30 dB was achieved using the active control system for both in-phase and out-of-phase monopoles; however, effective reduction of the sound field was dependent upon judiciously positioning the control forces for optimal control of the sound field.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27213399

  13. 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. PMID:27474187

  14. Kinetics of force recovery following length changes in active skinned single fibres from rabbit psoas muscle

    PubMed Central

    Burton, Kevin; Simmons, Robert M; Sleep, John; Smith, David A

    2006-01-01

    Redevelopment of isometric force following shortening of skeletal muscle is thought to result from a redistribution of cross-bridge states. We varied the initial force and cross-bridge distribution by applying various length-change protocols to active skinned single fibres from rabbit psoas muscle, and observed the effect on the slowest phase of recovery (‘late recovery’) that follows transient changes. In response to step releases that reduced force to near zero (∼8 nm (half sarcomere)−1) or prolonged shortening at high velocity, late recovery was well described by two exponentials of approximately equal amplitude and rate constants of ∼2 s−1 and ∼9 s−1 at 5°C. When a large restretch was applied at the end of rapid shortening, recovery was accelerated by (1) the introduction of a slow falling component that truncated the rise in force, and (2) a relative increase in the contribution of the fast exponential component. The rate of the slow fall was similar to that observed after a small isometric step stretch, with a rate of 0.4–0.8 s−1, and its effects could be reversed by reducing force to near zero immediately after the stretch. Force at the start of late recovery was varied in a series of shortening steps or ramps in order to probe the effect of cross-bridge strain on force redevelopment. The rate constants of the two components fell by 40–50% as initial force was raised to 75–80% of steady isometric force. As initial force increased, the relative contribution of the fast component decreased, and this was associated with a length constant of about 2 nm. The results are consistent with a two-state strain-dependent cross-bridge model. In the model there is a continuous distribution of recovery rate constants, but two-exponential fits show that the fast component results from cross-bridges initially at moderate positive strain and the slow component from cross-bridges at high positive strain. PMID:16497718

  15. 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.

  16. 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

  17. Local sources of global climate forcing from different categories of land use activities

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    Identifying and quantifying the sources of climate impacts from land use and land cover change (LULCC) is necessary to optimize policies regarding LULCC for climate change mitigation. These climate impacts are typically defined relative to emissions of CO2, or sometimes emissions of other long-lived greenhouse gases. Here we use previously published estimates of the radiative forcing (RF) of LULCC that include the short-lived forcing agents O3 and aerosols, in addition to long-lived greenhouse gases and land albedo change, for six projections of LULCC as a metric for quantifying climate impacts. The LULCC RF is attributed to three categories of LULCC activities: direct modifications to land cover, agriculture, and wildfire response, and sources of the forcing are ascribed to individual grid points for each sector. Results for the year 2010 show substantial positive forcings from the direct modifications and agriculture sectors, particularly from south and southeast Asia, and a smaller magnitude negative forcing response from wildfires. The spatial distribution of future sources of LULCC RF is highly scenario-dependent, but we show that future forest area change can be used as a predictor of the future RF from direct modification activities, especially in the tropics, suggesting that deforestation-prevention policies that value land based on its C-content may be particularly effective at mitigating climate forcing originating in the tropics from this sector. However, the response of wildfire RF to tropical land cover changes is not as easily scalable and yet imposes a non-trivial feedback onto the total LULCC RF.

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

    PubMed

    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

  20. 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

  1. Sales force development in health services organizations; a boundary spanning perspective.

    PubMed

    Kornuszko, M A; Gamm, L D

    1990-01-01

    Sales force development is of growing importance to HSOs in their increasingly competitive and heterogenous health care markets. There is always some danger that, under such circumstances, strategies new to HSOs will be adopted without sufficient attention to how they function and how they might best be integrated into the organization's overall mission. The sales force is becoming an important part of administration in the modern HSO. Ensuring that sales personnel effectively meet the needs of clients and of all relevant units of their HSO calls for attention to a number of concerns raised in organization-environment theory. Concepts from the literature on organizational boundaries and boundary spanning used here organize and illuminate major issues in sales force development. The approach taken is one which underscores the importance of these issues, illustrates some possible responses, and encourages HSO administrators to reflect on organizational implications of sales force development. The perspective offered provides a base for more detailed design considerations in planning and implementing a sales force. PMID:10106600

  2. 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

  3. Image-based synchronization of force and bead motion in active electromagnetic microrheometry

    NASA Astrophysics Data System (ADS)

    Park, Chang-Young; Saleh, Omar A.

    2014-12-01

    In the past, electromagnetic tweezers have been used to make active microrheometers. An active microrheometer measures the dynamic mechanical properties of a material from the motion of embedded particles under external force, e.g. a sinusoidal magnetic force generated by a sinusoidal current on a coil. The oscillating amplitude and the phase lag of the motion are then used to estimate the material’s dynamic mechanical properties. The phase lag, in particular, requires precise synchronization of the particle motion with the external force. In previous works, synchronization difficulties have arisen from measuring two parameters with two instruments, one of them being a camera. We solved the synchronization issue by measuring two parameters with a single instrument, the camera alone. From captured images, particles can be tracked in three dimensions through an image-analysis algorithm while the current on the coil can be measured from the brightness of the image; this enables simultaneous synchronization of the phases of the driving current on the electromagnet coil and the motion of the magnetic probe particle. We calibrate the phase delay between the magnetic force and the particle’s motion in glycerol and confirm the calibration with a Hall probe. The technique is further tested by measuring the shear modulus of a polyacrylamide gel, and comparing the results to those obtained using a conventional rheometer.

  4. 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.

  5. 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.

  6. Development and experimental validation of an analytical model to predict the demoulding force in hot embossing

    NASA Astrophysics Data System (ADS)

    Omar, F.; Brousseau, E.; Elkaseer, A.; Kolew, A.; Prokopovich, P.; Dimov, S.

    2014-05-01

    During the demoulding stage of the hot embossing process, the force required to separate a polymer part from the mould should be minimized to avoid the generation of structural defects for the produced micro structures. However, the demoulding force is dependent on a number of process factors, which include the material properties, the demoulding temperature, the polymer pressure history and the design of the mould structures. In particular, these factors affect the chemical, physical and mechanical interactions between a polymer and the replication master during demoulding. The focus of the reported research is on the development and validation of an analytical model that takes into account the adhesion, friction and deformation phenomena to predict the required demoulding force in hot embossing under different processing conditions. The results indicate that the model predictions agree well with the experimental data obtained and confirm that the design of the mould affects the resulting demoulding force. In addition, the applied embossing load was observed to have a significant effect on demoulding. More specifically, the increase in pressure within the polymer raises the adhesion force while it also reduces the friction force due to the decrease in the thermal stress.

  7. 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. PMID:25020237

  8. 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.

  9. 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. PMID:26925858

  10. 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,…

  11. Adult mouse motor units develop almost all of their force in the subprimary range: a new all-or-none strategy for force recruitment?

    PubMed

    Manuel, Marin; Heckman, C J

    2011-10-19

    Classical studies of the mammalian neuromuscular system have shown an impressive adaptation match between the intrinsic properties of motoneurons and the contractile properties of their motor units. In these studies, the rate at which motoneurons start to fire repetitively corresponds to the rate at which individual twitches start to sum, and the firing rate increases linearly with the amount of excitation ("primary range") up to the point where the motor unit develops its maximal force. This allows for the gradation of the force produced by a motor unit by rate modulation. In adult mouse motoneurons, however, we recently described a regime of firing ("subprimary range") that appears at lower excitation than what is required for the primary range, a finding that might challenge the classical conception. To investigate the force production of mouse motor units, we simultaneously recorded, for the first time, the motoneuron discharge elicited by intracellular ramps of current and the force developed by its motor unit. We showed that the motor unit developed nearly its maximal force during the subprimary range. This was found to be the case regardless of the input resistance of the motoneuron, the contraction speed, or the tetanic force of the motor unit. Our work suggests that force modulation in small mammals mainly relies on the number of motor units that are recruited rather than on rate modulation of individual motor units. PMID:22016552

  12. Motor nucleus activity fails to predict extraocular muscle forces in ocular convergence.

    PubMed

    Miller, Joel M; Davison, Ryan C; Gamlin, Paul D

    2011-06-01

    For a given eye position, firing rates of abducens neurons (ABNs) generally (Mays et al. 1984), and lateral rectus (LR) motoneurons (MNs) in particular (Gamlin et al. 1989a), are higher in converged gaze than when convergence is relaxed, whereas LR and medial rectus (MR) muscle forces are slightly lower (Miller et al. 2002). Here, we confirm this finding for ABNs, report a similarly paradoxical finding for neurons in the MR subdivision of the oculomotor nucleus (MRNs), and, for the first time, simultaneously confirm the opposing sides of these paradoxes by recording physiological LR and MR forces. Four trained rhesus monkeys with binocular eye coils and custom muscle force transducers on the horizontal recti of one eye fixated near and far targets, making conjugate saccades and symmetric and asymmetric vergence movements of 16-27°. Consistent with earlier findings, we found in 44 ABNs that the slope of the rate-position relationship for symmetric vergence (k(V)) was lower than that for conjugate movement (k(C)) at distance, i.e., mean k(V)/k(C) = 0.50, which implies stronger LR innervation in convergence. We also found in 39 MRNs that mean k(V)/k(C) = 1.53, implying stronger MR innervation in convergence as well. Despite there being stronger innervation in convergence at a given eye position, we found both LR and MR muscle forces to be slightly lower in convergence, -0.40 and -0.20 g, respectively. We conclude that the relationship of ensemble MN activity to total oculorotary muscle force is different in converged gaze than when convergence is relaxed. We conjecture that LRMNs with k(V) < k(C) and MRMNs with k(V) > k(C) innervate muscle fibers that are weak, have mechanical coupling that attenuates their effective oculorotary force, or serve some nonoculorotary, regulatory function. PMID:21451064

  13. 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

  14. 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. PMID:25914206

  15. 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.

  16. Florida Model Task Force on Diabetic Retinopathy: Development of an Interagency Network.

    ERIC Educational Resources Information Center

    Groff, G.; And Others

    1990-01-01

    This article describes the development of a mechanism to organize a network in Florida for individuals who are at risk for diabetic retinopathy. The task force comprised representatives from governmental, academic, professional, and voluntary organizations. It worked to educate professionals, patients, and the public through brochures, resource…

  17. 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…

  18. Development and Experimental Evaluation of a Retrieval System for Air Force Control Display Information. Final Report.

    ERIC Educational Resources Information Center

    Debons, Anthony; and Others

    A proposed classification system was studied to determine its efficacy to the Air Force Control-Display Area. Based on negative outcomes from a logical assessment of the proposed system, an alternate system was proposed to include the coordinate index concept. Upon development of a thesaurus and an index system for 106 documents on VSTOL/VTOL…

  19. Factors Affecting Work Force Development in the People's Republic of China.

    ERIC Educational Resources Information Center

    Sredl, Henry J.

    Work force development in the Peoples' Republic of China (PRC) is affected by sundry but interrelated factors. Included among these are the following: (1) the PRC's population of one billion people; (2) a recent history of political turmoil and violence, resulting in profound changes in national leadership and vacillation in national policy; (3)…

  20. 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 2…

  1. Biomechanical force in blood development: extrinsic physical cues drive pro-hematopoietic signaling

    PubMed Central

    Lee, Hyun Jung; Li, Nan; Evans, Siobahn M.; Diaz, Miguel F.; Wenzel, Pamela L.

    2013-01-01

    The hematopoietic system is dynamic during development and in adulthood, undergoing countless spatial and temporal transitions during the course of one’s life. Microenvironmental cues in the many unique hematopoietic niches differ, characterized by distinct soluble molecules, membrane-bound factors, and biophysical features that meet the changing needs of the blood system. Research from the last decade has revealed the importance of substrate elasticity and biomechanical force in determination of stem cell fate. Our understanding of the role of these factors in hematopoiesis is still relatively poor; however, the developmental origin of blood cells from the endothelium promts a model for comparison. Many endothelial mechanical sensors and second messenger systems may also determine hematopoietic stem cell fate, self renewal, and homing behaviors. Further, the intimate contact of hematopoietic cells with mechanosensitive cell types, including osteoblasts, endothelial cells, mesenchymal stem cells, and pericytes, places them in close proximity to paracrine signaling downstream of mechanical signals. The objective of this review is to present an overview of the sensors and intracellular signaling pathways activated by mechanical cues and highlight the role of mechanotransductive pathways in hematopoiesis. PMID:23850217

  2. 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. PMID:25695853

  3. 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

  4. 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

  5. Changes in muscle activation and force generation patterns during cycling movements because of low-intensity squat training with slow movement and tonic force generation.

    PubMed

    Tanimoto, Michiya; Arakawa, Hiroshi; Sanada, Kiyoshi; Miyachi, Motohiko; Ishii, Naokata

    2009-11-01

    Our previous studies showed that relatively low-load (approximately 50-60% 1 repetition maximum [1RM]) resistance training with slow movement and tonic force generation (LST) significantly increased muscle size and strength. However, LST is a very specific movement that differs from natural movements associated with sport activities and activities of daily life, and therefore, it might have some unfavorable effects on dynamic sport movement. We investigated the effects of LST on muscle activity and force generation patterns during cycling movement as a representative dynamic sports movement. Twenty-four healthy young men who were not in the habit of bicycle riding and did not have a history of regular resistance training were randomly assigned to the LST (approximately 60% 1RM load, 3-second lifting, and 3-second lowering movement without a relaxing phase: n = 8), a high-intensity exercise at normal speed (HM) group (85% 1RM load, 1-second lifting, 1-second lowering, and 1-second relaxed movement: n = 8), or sedentary control (CON, n = 8) group. Subjects in the training groups performed vertical squats by the assigned method. Exercise sessions consisted of 3 sets and were performed twice a week for 13 weeks. Pre- and posttraining muscle activation and force generation patterns during the cycling movements were evaluated by the coefficient of variation (CV) of the rectified electromyographic (EMG) wave from the vastus lateralis and CV of pedaling force. Both the CV of the rectified EMG and of pedaling force decreased significantly in the LST group (-21 and -18%, p < 0.05, respectively), whereas there were no significant changes in either the HN or the CON group. This decrease in CV in the LST group could mean that muscle activity and force generation during cycling movement have become more tonic. This result following LST may have an unfavorable effect on cycling movement and other dynamic sports movements. PMID:19826286

  6. Development of A Miniaturized 3-DOF Force Sensing Instrument for Robotically Assisted Retinal Microsurgery and Preliminary Results*

    PubMed Central

    He, Xingchi; Gehlbach, Peter; Handa, James; Taylor, Russell; Iordachita, Iulian

    2014-01-01

    Lack of force sensing is one of the most formidable technical challenges in retinal microsurgery. Incorporating high sensitivity force sensing into the ophthalmic tools has the potential to provide the surgeon useful force feedback and to enable safe robotic assistance. This paper presents a new design of a three degrees of freedom force sensing instrument based on fiber Bragg grating sensors. A new flexure is developed to achieve high axial force sensing sensitivity and low crosstalk noise. The force sensing segment of the tool, located directly proximal to the tool tip, is ø0.9×8 mm. An extensive calibration shows that the force sensor can measure the transverse and axial force up to 21 mN with 0.5 mN and 3.3 mN accuracy, respectively. The new flexure design demonstrates the potential to improve axial force sensing. Analysis of the experiment results suggests improvements for the future iteration. PMID:25544966

  7. 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

  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. 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

  10. 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.

  11. Activities to Encourage Speech and Language Development

    MedlinePlus

    ... and Swallowing / Development Activities to Encourage Speech and Language Development Birth to 2 Years Encourage your baby ... or light) of the packages. Typical Speech and Language Development Learning More Than One Language Adult Speech ...

  12. Development of Ceramic Coatings for Electrostatic Adsorption Force using Atmospheric Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Takeuchi, Jun-Ichi; Yamasaki, Ryo; Tani, Kazumi

    In state-of-the art semiconductor equipment such as dry etchers, CVD and PVD chambers as well as in the liquid crystal manufacturing industry, it is very important to consistently keep silicon wafers or glass on the susceptor. The main objectives are to improve the accuracy of both positioning and temperature control. Generally electrostatic adsorption force is used for holding silicon wafers or glass inside of a treatment chamber. The sintered ceramics, the polymer resin, and the thermal sprayed ceramic coatings are used as the dielectric substance to isolate and protect the surface of the electrostatic chuck and limit contamination and particle generation. However, investigations of the electrostatic adsorption force through thermal sprayed ceramic coatings have been limited. In this study, a ceramic coating having the electrostatic adsorption force was developed and its basic mechanical and electrical characteristics were investigated, and compared with those of sintered ceramics.

  13. 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. PMID:10180553

  14. Development of AMOEBA force field for 1,3-dimethylimidazolium based ionic liquids.

    PubMed

    Starovoytov, Oleg N; Torabifard, Hedieh; Cisneros, G Andrés

    2014-06-26

    The development of AMOEBA (a multipolar polarizable force field) for imidazolium based ionic liquids is presented. Our parametrization method follows the AMOEBA procedure and introduces the use of QM intermolecular total interactions as well as QM energy decomposition analysis (EDA) to fit individual interaction energy components. The distributed multipoles for the cation and anions have been derived using both the Gaussian distributed multipole analysis (GDMA) and Gaussian electrostatic model-distributed multipole (GEM-DM) methods.1 The intermolecular interactions of a 1,3-dimethylimidazolium [dmim(+)] cation with various anions, including fluoride [F(-)], chloride [Cl(-)], nitrate [NO(3)(-)], and tetraflorouborate [BF(4)(-)], were studied using quantum chemistry calculations at the MP2/6-311G(d,p) level of theory. Energy decomposition analysis was performed for each pair using the restricted variational space decomposition approach (RVS) at the HF/6-311G(d,p) level. The new force field was validated by running a series of molecular dynamic (MD) simulations and by analyzing thermodynamic and structural properties of these systems. A number of thermodynamic properties obtained from MD simulations were compared with available experimental data. The ionic liquid structure reproduced using the AMOEBA force field is also compared with the data from neutron diffraction experiment and other MD simulations. Employing GEM-DM force fields resulted in a good agreement on liquid densities ρ, enthalpies of vaporization ΔH(vap), and diffusion coefficients D(±) in comparison with conventional force fields. PMID:24901255

  15. Development of High-Force-Density Iron-Core Linear Synchronous Motor

    NASA Astrophysics Data System (ADS)

    Kakihara, Masanobu; Hoshi, Toshiyuki; Shikayama, Toru; Ohto, Motomichi

    The demand for small-sized and high-acceleration linear motors for industrial machines such as semiconductor production equipment and LCD equipment is rapidly increasing in order to maintain the small size of these equipment and to increase productivity. To satisfy the demand, high-force-density (i.e., force per volume) linear motors are required. This paper discusses the development of a high-force-density iron-core linear synchronous motor that consists of a Halbach magnet array with soft magnetic material and a grain-oriented silicon steel sheet core; the motor has a shape-optimized design. The motor constant square density of the new linear motor reaches 10N2/W/cm3, while that of the highest force linear motor available at present is 5N2/W/cm3. In other words, the new motor can deliver a force of 900N per 1000cm3. In this paper, details of the design, especially the structure and performance of the new motor are presented, and the design is validated on the basis of measurements of a prototype motor.

  16. 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. PMID:22984953

  17. Classroom Activities to Develop Creativity.

    ERIC Educational Resources Information Center

    Cornish, Robert L., Ed.

    A vitally important objective for the classroom teacher is to foster children's creative thinking. In this activity book for teachers of young children, the need for independence and creativity in modern society is discussed as an antidote for the conformity and depersonalization characteristic of our culture. Teacher flexibility and acceptance of…

  18. Time Evolution of Force-Free Parameter and Free Magnetic Energy in Active Region NOAA 10365

    NASA Astrophysics Data System (ADS)

    Valori, G.; Romano, P.; Malanushenko, A.; Ermolli, I.; Giorgi, F.; Steed, K.; van Driel-Gesztelyi, L.; Zuccarello, F.; Malherbe, J.-M.

    2015-02-01

    We describe the variation of the accumulated coronal helicity derived from the magnetic helicity flux through the photosphere in active region (AR) NOAA 10365, where several large flares and coronal mass ejections (CMEs) occurred. We used SOHO/MDI full-disk line-of-sight magnetograms to measure the helicity flux, and the integral of GOES X-ray flux as a proxy of the coronal energy variations due to flares or CMEs. Using the linear force-free field model, we transformed the accumulated helicity flux into a time sequence of the force-free parameter α accounting for flares or CMEs via the proxy derived from GOES observations. This method can be used to derive the value of α at different times during the AR evolution, and is a partial alternative to the commonly used match of field lines with EUV loops. By combining the accumulated helicity obtained from the observations with the linear force-free theory, we describe the main phases of the emergence process of the AR, and relate them temporally with the occurrence of flares or CMEs. Additionally, a comparison with the loop-matching method of fixing alpha at each time independently shows that the proposed method may be helpful in avoiding unrealistic or undetermined values of alpha that may originate from an insufficient quality of the image used to identify coronal loops at a given time. For the relative intensity of the considered events, the linear force-free field theory implies that there is a direct correlation between the released energy on the one hand and the product of the coronal helicity with the variation of α due to the event on the other. Therefore, the higher the value of the accumulated coronal helicity, the smaller the force-free parameter variation required to produce the same decrease in the free energy during the CMEs.

  19. 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

  20. 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.

  1. 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

  2. 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. PMID:24663619

  3. 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

  4. 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

  5. Force irradiation effects during upper limb diagonal exercises on contralateral muscle activation.

    PubMed

    Abreu, Rosa; Lopes, Alfredo Alexandre; Sousa, Andreia S P; Pereira, Soraia; Castro, Marcelo P

    2015-04-01

    The aim of this study was to explore the force irradiation effects of upper limb isometric diagonal exercises on shoulder muscle activities. Interactions among diagonal directions, contraction intensities (moderate and maximum) and sex were assessed. Thirty healthy subjects (11 males) performed isometric unilateral diagonal exercises based on proprioceptive neuromuscular facilitation technique in an isokinetic dynamometer with their dominant upper limbs. The second diagonal for flexion and for extension were assessed while the participants performed their maximum isometric torque (MIT) and at 25% of their MIT. During the exercise the muscle activity of the medial deltoid, pectoralis major and upper trapezius in the non-dominant (non-exercised) upper limbs of the participants was recorded by surface electromyography. The highest muscle activity occurred in the upper trapezius during the diagonal for flexion (27% of maximum isometric voluntary contractions). Upper trapezius and pectoralis major were more active during the diagonal for flexion than diagonal for extension (p < 0.001), while similar values between both diagonals were observed for the medial deltoid (p > 0.05). In conclusion, we observed that force irradiation during upper limb diagonal exercises is affected by diagonal direction, contraction intensity and sex when performed by healthy participants. PMID:25592384

  6. 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

  7. 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.

  8. 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…

  9. 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.

  10. 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.

  11. 1987 status report - United States Air Force electric propulsion research and development

    SciTech Connect

    Meya, R.D.; Nguyen, T.H.Q.

    1987-05-01

    The Air Force Astronautics Laboratory (AFAL) is currently developing electric propulsion technology to meet USAF and DOD requirements for military space missions. The AFAL's three-tiered RandD program is presented. In order of priority, the first tier is the space demonstration of a space-qualified 30-kWe-class arcjet propulsion system, while the second tier is the continued industrial development of arcjet technology to increase specific impulse and lifetime; the third tier is the continued university development of steady-state multimegawatt MPD thrusters to guarantee the availability of MPD technology upon USAF deployment of operational multimegawatt space power supplies. 12 references.

  12. 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).

  13. Forced eruption and implant site development in the aesthetic zone: A case report.

    PubMed

    Keceli, Huseyin Gencay; Guncu, Mustafa Baris; Atalay, Zeynep; Evginer, Mustafa Serdar

    2014-04-01

    A multidisciplinary approach to develop the future implant site in the aesthetic zone was illustrated. A patient with perio-endo combined lesion at her upper central incisors was treated. Before extraction, forced eruption was performed and 12 months later, satisfactory amount of bone apposition was detected. At 2 weeks after atraumatic extraction, implants were placed and loaded with implant-supported restorations following osseous healing. Variables related to crown dimensions, periodontal/peri-implanter soft-tissue health and patient's aesthetic satisfaction were recorded at baseline, before extraction and after prosthetic treatment. At 12-month control, crown dimensions in the implant site were identical to the baseline and in addition to the healthy peri-implant tissues, successful aesthetics were obtained. Forced eruption is a successful non-invasive method to develop the aesthetics of the peri-implant tissues and implant-supported restorations. PMID:24966782

  14. Forced eruption and implant site development in the aesthetic zone: A case report

    PubMed Central

    Keceli, Huseyin Gencay; Guncu, Mustafa Baris; Atalay, Zeynep; Evginer, Mustafa Serdar

    2014-01-01

    A multidisciplinary approach to develop the future implant site in the aesthetic zone was illustrated. A patient with perio-endo combined lesion at her upper central incisors was treated. Before extraction, forced eruption was performed and 12 months later, satisfactory amount of bone apposition was detected. At 2 weeks after atraumatic extraction, implants were placed and loaded with implant-supported restorations following osseous healing. Variables related to crown dimensions, periodontal/peri-implanter soft-tissue health and patient's aesthetic satisfaction were recorded at baseline, before extraction and after prosthetic treatment. At 12-month control, crown dimensions in the implant site were identical to the baseline and in addition to the healthy peri-implant tissues, successful aesthetics were obtained. Forced eruption is a successful non-invasive method to develop the aesthetics of the peri-implant tissues and implant-supported restorations. PMID:24966782

  15. The role of elastic energy in activities with high force and power requirements: a brief review.

    PubMed

    Wilson, Jacob M; Flanagan, Eamonn P

    2008-09-01

    The purpose of this article is to provide strength and conditioning practitioners with an understanding of the role of elastic energy in activities with high force and power requirements. Specifically, the article covers 1) the nature of elasticity and its application to human participants, 2) the role of elastic energy in activities requiring a stretch-shorten cycle such as the vertical jump, 3) the role of muscular stiffness in athletic performance, 4) the control of muscular stiffness through feedforward and feedback mechanisms, and 5) factors affecting muscular stiffness. Finally, practical applications are provided. In this section, it is suggested that the storage and reuse of elastic energy is optimized at relatively higher levels of stiffness. Because stiffness decreases as fatigue ensues as well as with stretching before an event, the article emphasizes the need for proper preparation phases in a periodized cycle and the avoidance of long static stretches before high-force activities. The importance of teaching athletes to transition from eccentric to concentric movements with minimal time delays is also proposed due to the finding that time delays appear to decrease the reuse of elastic energy. In addition to teaching within the criterion tasks, evidence is provided that minimizing transitions in plyometric training, a technique demonstrated to increase musculotendinous stiffness, can optimize power output in explosive movements. Finally, evidence is provided that training and teaching programs designed to optimize muscular stiffness may protect athletes against sports-related injuries. PMID:18714212

  16. Kank2 activates talin, reduces force transduction across integrins and induces central adhesion formation.

    PubMed

    Sun, Zhiqi; Tseng, Hui-Yuan; Tan, Steven; Senger, Fabrice; Kurzawa, Laetitia; Dedden, Dirk; Mizuno, Naoko; Wasik, Anita A; Thery, Manuel; Dunn, Alexander R; Fässler, Reinhard

    2016-09-01

    Integrin-based adhesions play critical roles in cell migration. Talin activates integrins and flexibly connects integrins to the actomyosin cytoskeleton, thereby serving as a 'molecular clutch' that transmits forces to the extracellular matrix to drive cell migration. Here we identify the evolutionarily conserved Kank protein family as novel components of focal adhesions (FAs). Kank proteins accumulate at the lateral border of FAs, which we term the FA belt, and in central sliding adhesions, where they directly bind the talin rod domain through the Kank amino-terminal (KN) motif and induce talin and integrin activation. In addition, Kank proteins diminish the talin-actomyosin linkage, which curbs force transmission across integrins, leading to reduced integrin-ligand bond strength, slippage between integrin and ligand, central adhesion formation and sliding, and reduced cell migration speed. Our data identify Kank proteins as talin activators that decrease the grip between the integrin-talin complex and actomyosin to regulate cell migration velocity. PMID:27548916

  17. 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

  18. 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.

  19. [Prospects of perfection and development of the technical devices of medical assignment in foreign armed forces].

    PubMed

    Bukhtiiarov, I V; Medvedev, V R; Petrovskiĭ, G V; Varfolomeev, V A; Pozdniakov, A V; Tushnova, L K

    2010-12-01

    In the article was analyzed the usage of the technical devices of medical assignment of NATO armed forces during the last military conflicts in different countries and prospects of its perfection. Among the most important programs were outlined: work on the systems of telemedicine with possibility of its usage in battle conditions, development of the independent life-support system in case of battle trauma and progressive medical mobile centers on the base of new motor carrier. PMID:21488360

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. Human Development Program: Level VI Activity Guide.

    ERIC Educational Resources Information Center

    Ball, Geraldine

    The curriculum guide presents the activities component of the Human Development Program for grade 6. The Human Development Program (HDP) is an affective curricular approach developed by psychologists to aid teachers in instilling responsibility and self-confidence in children. The nucleus of the Human Development Program is a circle session…

  6. 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

  7. 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.

  8. Separable Solutions of Force-Free Spheres and Applications to Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Prasad, A.; Mangalam, A.; Ravindra, B.

    2014-05-01

    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 ψvprop1/rn and the field Bvprop1/r 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.

  9. Computer Game Development as a Literacy Activity

    ERIC Educational Resources Information Center

    Owston, Ron; Wideman, Herb; Ronda, Natalia Sinitskaya; Brown, Christine

    2009-01-01

    This study examined computer game development as a pedagogical activity to motivate and engage students in curriculum-related literacy activities. We hypothesized that as a consequence, students would improve their traditional reading and writing skills as well as develop new digital literacy skills. Eighteen classes of grade 4 students were…

  10. Effect of seat positions on discomfort, muscle activation, pressure distribution and pedal force during cycling.

    PubMed

    Verma, Rachita; Hansen, Ernst A; de Zee, Mark; Madeleine, Pascal

    2016-04-01

    The aim of this study was to measure and analyse discomfort and biomechanics of cycling, i.e., muscle activation, centre of pressure of seat pressure profiles and pedal forces as a function of seat position. Twenty-one recreationally active individuals cycled for 10min at 100W on an ergometer cycle using five different seat positions. The neutral position was considered as basic seat position and was compared with upward, downward, forward and backward seat positions. The initial bout was repeated at the end of the recording session. Discomfort increased for upward and backward condition compared with neutral (P<0.05). Normalized surface electromyography from gastrocnemius decreased in the downward and forward position but increased in the upward and backward position. The minimum force became less negative for forward position compared with neutral seat position (P<0.05). The degree of variability of centre of pressure increased in the upward and backward position and the entropy of the centre of pressure of sitting posture for backward position decreased compared with neutral seat position (P<0.05). The present study revealed that consecutive changes of seat position over time lead to increase in discomfort as well as alterations of the biomechanics of cycling. PMID:26938676

  11. Comparison of buoyancy, passive and net active drag forces between Fastskin and standard swimsuits.

    PubMed

    Benjanuvatra, N; Dawson, G; Blanksby, B A; Elliott, B C

    2002-06-01

    A cross-sectional comparison between the buoyancy, passive and net active drag force characteristics of full-length, Fastskin swimsuits with that of standard swimsuits was completed with nine Open National level swimmers (5 males and 4 females). Subjects were weighed in a hydrostatic tank and then towed via a mechanical winch on the surface and 0.4 m deep at 1.6, 2.2 and 2.8 m/s. The subjects performed a prone streamlined glide and maximum effort flutter kick at each towing velocity and depth. Hydrostatic weight differences between swimsuit types were not significant (p> 0.05. Fastskin passive drag values were significantly less than normal swimsuits during surface towing at 1.6 and 2.8 m/s: and at 0.4 m deep towing at 1.6, 2.2 and 2.8 m/s. Net active drag force values also were lower for the Fastskin suits when compared with those of normal swimsuits and a significant difference existed for surface towing at all three velocities of 1.6, 2.2 and 2.8 m/s. The full-length, Fastskin swimsuits created less total hydrodynamic resistance than normal swimsuits while providing no additional buoyancy benefits. PMID:12188083

  12. Active optics correction forces for the VST 2.6m primary mirror

    NASA Astrophysics Data System (ADS)

    Schipani, P.; Perrotta, F.; Marty, L.

    2006-06-01

    In active optics systems obviously a fundamental role is played be the choice of polynomials to describe the primary mirror deformations. The well known Zernike polynomials are widely used because of their immediate interpretation in terms of optical aberrations. Nevertheless in an active optics correction system context, the choice of the so called "minimum energy modes" as the polynomials to represent the mechanical deformations is best justified by their derivation from mechanical properties. This is the approach followed for the 2.6m primary mirror of the VST telescope, to be hosted on top of the Cerro Paranal ESO observatory. The calibration forces to compensate a given amount of each aberration mode are computed and discussed.

  13. Adjust the labour force structure and energetically develop the tertiary industry.

    PubMed

    Feng, R; Wang, J

    1987-01-01

    In 1984 approximately 12.1% of the employed population in Zhejiang Province were in the tertiary industry, which is an increase over 1978's 8.1%. However, the province's level lags behind the national level. Changes in the province's labor force in the tertiary industry can be divided into 4 periods: 1) 1952-1957, a period of rather rapid development; 2) 1958-1962, marked by many great fluctuations (the percent of tertiary labor force rose from 7.1% to 12.6% and fell to 7.1%); 3) 1963-1978, a period of fluctuation between 8.1% and less than 7%; and 4) 1979-1984, a period of recovery and rather rapid development, when the percent of tertiary labor force rose from 9.1% in 1980 to 12.1% in 1984. The slow development of the tertiary industry resulted in the following: 1) an irrational urban-rural structure of the tertiary industry, 2) a growing tension in the transportation and telecommunication industries because of their insufficient development, 3) reduction of commerce and service trade, 4) a small proportion of industries aimed at raising the knowledge level (2.6% of the province's total employed versus 3.7% of the nation's), 5) poorly systematized living installations and public utilities, and 6) an increasing problem of disposition of the labor force. Favorable conditions for the development of Zhejiang Province's tertiary industry include 1) both the Party Central and the State Council give priority to the tertiary industry; 2) in recent years, industrial and agricultural productions have developed rapidly and the labor productivities of primary and secondary industries have been raised;) 3) there have been improved living standards and changes in consumption structure, and 4) light industry and agriculture, favorable for the development of the tertiary industry, are the major components of the province's economy. Some suggestions for developing the tertiary industry are 1) increase understanding and plan comprehensively, 2) provide comprehensive service with

  14. Repeated measurements of respiratory mechanics in developing rats utilizing a forced oscillation technique.

    PubMed

    Heulitt, Mark J; Jones, Stacie M; Holt, Shirley J; Thurman, Tracy L; Jo, Chan-Hee; Simpson, Pippa M

    2008-09-01

    The ability to successfully intubate the trachea of rats repeatedly over time, recover them, and perform repeated measures of changes in respiratory mechanics is important. The authors performed experiments utilizing 2 groups of rats at various ages in their development. Rats in the single-measurement group were studied at 1 age only. Rats in the repeated-measurement group were studied at each age point over time. Measurements of respiratory mechanics were made utilizing a forced-oscillation technique. We found no differences in respiratory mechanics between the 2 groups. Our results demonstrate that developing rats can be studied longitudinally to illustrate maturational changes in respiratory mechanics. PMID:18716927

  15. 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

  16. 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

    2016-01-01

    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

  17. Development and implementation of configurational forces based constitutive phase field models for shape memory alloys

    NASA Astrophysics Data System (ADS)

    Agboola, Babatunde Omogbolahan

    Continuum thermodynamic constitutive phase field models are developed to simulate the rate dependent, thermomechanical response and precipitate formation in shape memory alloys (SMAs). The two models are based on the application of the balance of configurational forces, a scalar order parameter (a phase field) and atomic concentration to extend standard continuum thermodynamics approach. Constitutive field equations that capture the kinetics of solid-solid martensitic phase transition in SMA and the diffusion mediated precipitate formation in an elastic solid are developed. The coupled set of thermodynamically consistent field equations results from balance of configuration forces, balance of linear momentum, balance of energy and balance of atomic species mass. The field equations capture the kinetics of phase transition, deformation and elastic wave, heat transfer and atomic diffusion respectively. The first model is thermomechanical and is used to simulate the macroscopic response of SMA such as pseudoelasticity; transformation induced pseudo-creep, stress relaxation as well as the effect of cooling rate on mechanical and thermally induced phase transformation of SMA. The second model couples diffusion with elasticity to simulate growth and coarsening of precipitate and experimentally observed concentration depletion near the precipitates Results of the simulations of the macroscopic SMA response are in very good agreement with experimental observation. Simulations suggest that rate dependent and complex thermomechanical response of SMA are due to the interaction of an inherent time scale ( as well as length scale) of phase transformation, introduced through the balance of configurational forces, with other time scales. This work contributes to improved SMA modeling, scientific understanding and design. In particular, for aerospace application under stringent requirement and severe environmental conditions. Contribution of fundamental use of balance of

  18. [The development of the female labor force in Belgium: Part 1, trends from 1970 to 1977].

    PubMed

    Broerman, M

    1980-01-01

    In the 1st section, the evolution of the active female population in Belgium was examined as a function of some social and demographic variables. The comparisons made cover the period 1970-77. The evolution in the rate of female activity during these 2 dates was analyzed and it was found that participation of women in economic activities is increasing. This is a recent phenomenon despite the serious economic recession Belgium has been experiencing since 1974. On examination of the overall volume of females employed in the total labor force, it was noted that the female labor force grew much more than did the male labor force. This increase in female activity made it possible to maintain the general rate of activity in the country. With regard to unemployment, there is an enormous disparity between the number of unemployed males and females. There is a rapidly rising trend in the number of females unemployed. In 1979, the rate of female unemployment was 3 times the rate of that of males. This situation existed in spite of the fact that the level of education in unemployed women was found to be distinctly higher than that of unemployed men. This was especially true of women less than 25 years of age who form a particularly vulnerable group. The influence of age on the activity curve of women was also studied. Peaks in 1977 existed for those ages 20-29, an age during which women raise young children. This discovery is confirmed by the remarkable advance in the activity of married women, which although recent, has taken on spectacular proportions during the last decade. The declining age at marriage, decreasing fertility, a rising trend for women in 1977 to postpone their 1st birth, and the decrease in family size are all factors which only must be briefly analyzed to discover that women in 1977 are in better position to participate in the professional world. They thereby display a desire to arrive at independence through work in spite of the obstacles encountered in

  19. A Statistical Analysis of Activity-Based and Traditional Introductory Algebra Physics Using the Force and Motion Conceptual Evaluation

    NASA Astrophysics Data System (ADS)

    Trecia Markes, Cecelia

    2006-03-01

    With a three-year FIPSE grant, it has been possible at the University of Nebraska at Kearney (UNK) to develop and implement activity- based introductory physics at the algebra level. It has generally been recognized that students enter physics classes with misconceptions about motion and force. Many of these misconceptions persist after instruction. Pretest and posttest responses on the ``Force and Motion Conceptual Evaluation'' (FMCE) are analyzed to determine the effectiveness of the activity- based method of instruction relative to the traditional (lecture/lab) method of instruction. Data were analyzed to determine the following: student understanding at the beginning of the course, student understanding at the end of the course, how student understanding is related to the type of class taken, student understanding based on gender and type of class. Some of the tests used are the t-test, the chi-squared test, and analysis of variance. The results of these tests will be presented, and their implications will be discussed.

  20. 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

  1. RACORO continental boundary layer cloud investigations: 1. Case study development and ensemble large-scale forcings

    NASA Astrophysics Data System (ADS)

    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

    2015-06-01

    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, κ, are derived from observations to be ~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 clouds.

  2. The rate of force development scaling factor (RFD-SF): protocol, reliability, and muscle comparisons.

    PubMed

    Bellumori, Maria; Jaric, Slobodan; Knight, Christopher A

    2011-07-01

    Performing a set of isometric muscular contractions to varied amplitudes with instructions to generate force most rapidly reveals a strong linear relationship between peak forces (PF) achieved and corresponding peak rates of force development (RFD). The slope of this relationship, termed the RFD scaling factor (RFD-SF), quantifies the extent to which RFD scales with contraction amplitude. Such scaling allows relative invariance in the time required to reach PF regardless of contraction size. Considering the increasing use of this relationship to study quickness and consequences of slowness in older adults and movement disorders, our purpose was to further develop the protocol to measure RFD-SF. Fifteen adults (19-28 years) performed 125 rapid isometric contractions to a variety of force levels in elbow extensors, index finger abductors, and knee extensors, on 2 days. Data were used to determine (1) how the number of pulses affects computation of the RFD-SF, (2) day-to-day reliability of the RFD-SF, and (3) the nature of RFD-SF differences between diverse muscle groups. While sensitive to the number of pulses used in its computation (P<.05), RFD-SF was reliable when computed with >50 pulses (ICC>.7) and more so with 100-125 pulses (ICC=.8-.92). Despite differences in size and function across muscles, RFD-SF was generally similar (i.e., only 8.5% greater in elbow extensors than in index finger abductors and knee extensors; P=.049). Results support this protocol as a reliable means to assess how RFD scales with PF in rapid isometric contractions as well as a simple, non-invasive probe into neuromuscular health. PMID:21656219

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. Effects of proprioceptive neuromuscular facilitation stretching on stiffness and force-producing characteristics of the ankle in active women.

    PubMed

    Rees, Sven S; Murphy, Aron J; Watsford, Mark L; McLachlan, Ken A; Coutts, Aaron J

    2007-05-01

    The purpose of this study was to examine the effect of proprioceptive neuromuscular facilitation (PNF) stretching on musculotendinous unit (MTU) stiffness of the ankle joint. Twenty active women were assessed for maximal ankle range of motion, maximal strength of planter flexors, rate of force development, and ankle MTU stiffness. Subjects were randomly allocated into an experimental (n = 10) group or control group (n = 10). The experimental group performed PNF stretching on the ankle joint 3 times per week for 4 weeks, with physiological testing performed before and after the training period. After training, the experimental group significantly increased ankle range of motion (7.8%), maximal isometric strength (26%), rate of force development (25%), and MTU stiffness (8.4%) (p < 0.001). Four weeks of PNF stretching contributed to an increase in MTU stiffness, which occurred concurrently with gains to ankle joint range of motion. The results confirm that MTU stiffness and joint range of motion measurements appear to be separate entities. The increased MTU stiffness after the training period is explained by adaptations to maximal isometric muscle contractions, which were a component of PNF stretching. Because a stiffer MTU system is linked with an improved the ability to store and release elastic energy, PNF stretching would benefit certain athletic performance due to a reduced contraction time or greater mechanical efficiency. The results of this study suggest PNF stretching is a useful modality at increasing a joint's range of motion and its strength. PMID:17530973

  8. Computational ligand-based rational design: Role of conformational sampling and force fields in model development

    PubMed Central

    Shim, Jihyun; MacKerell, Alexander D.

    2011-01-01

    A significant number of drug discovery efforts are based on natural products or high throughput screens from which compounds showing potential therapeutic effects are identified without knowledge of the target molecule or its 3D structure. In such cases computational ligand-based drug design (LBDD) can accelerate the drug discovery processes. LBDD is a general approach to elucidate the relationship of a compound's structure and physicochemical attributes to its biological activity. The resulting structure-activity relationship (SAR) may then act as the basis for the prediction of compounds with improved biological attributes. LBDD methods range from pharmacophore models identifying essential features of ligands responsible for their activity, quantitative structure-activity relationships (QSAR) yielding quantitative estimates of activities based on physiochemical properties, and to similarity searching, which explores compounds with similar properties as well as various combinations of the above. A number of recent LBDD approaches involve the use of multiple conformations of the ligands being studied. One of the basic components to generate multiple conformations in LBDD is molecular mechanics (MM), which apply an empirical energy function to relate conformation to energies and forces. The collection of conformations for ligands is then combined with functional data using methods ranging from regression analysis to neural networks, from which the SAR is determined. Accordingly, for effective application of LBDD for SAR determinations it is important that the compounds be accurately modelled such that the appropriate range of conformations accessible to the ligands is identified. Such accurate modelling is largely based on use of the appropriate empirical force field for the molecules being investigated and the approaches used to generate the conformations. The present chapter includes a brief overview of currently used SAR methods in LBDD followed by a more

  9. Computational ligand-based rational design: Role of conformational sampling and force fields in model development.

    PubMed

    Shim, Jihyun; Mackerell, Alexander D

    2011-05-01

    A significant number of drug discovery efforts are based on natural products or high throughput screens from which compounds showing potential therapeutic effects are identified without knowledge of the target molecule or its 3D structure. In such cases computational ligand-based drug design (LBDD) can accelerate the drug discovery processes. LBDD is a general approach to elucidate the relationship of a compound's structure and physicochemical attributes to its biological activity. The resulting structure-activity relationship (SAR) may then act as the basis for the prediction of compounds with improved biological attributes. LBDD methods range from pharmacophore models identifying essential features of ligands responsible for their activity, quantitative structure-activity relationships (QSAR) yielding quantitative estimates of activities based on physiochemical properties, and to similarity searching, which explores compounds with similar properties as well as various combinations of the above. A number of recent LBDD approaches involve the use of multiple conformations of the ligands being studied. One of the basic components to generate multiple conformations in LBDD is molecular mechanics (MM), which apply an empirical energy function to relate conformation to energies and forces. The collection of conformations for ligands is then combined with functional data using methods ranging from regression analysis to neural networks, from which the SAR is determined. Accordingly, for effective application of LBDD for SAR determinations it is important that the compounds be accurately modelled such that the appropriate range of conformations accessible to the ligands is identified. Such accurate modelling is largely based on use of the appropriate empirical force field for the molecules being investigated and the approaches used to generate the conformations. The present chapter includes a brief overview of currently used SAR methods in LBDD followed by a more

  10. [Illinois Career Development Month Ideas and Activities.

    ERIC Educational Resources Information Center

    Illinois State Board of Education, Springfield.

    This document is intended to help practitioners plan and implement activities for observance of Career Development Month in Illinois. Part 1 examines the following topics: the definitions of career development and education-to-careers; the rationale for devoting a month to career development; a career framework; and suggested Career Development…

  11. Human Development Program: Level III Activity Guide.

    ERIC Educational Resources Information Center

    Bessell, Harold

    The curriculum guide presents the activities component of the Human Development Program for the third grade. The Human Development Program (HDP) is an affective curricular approach developed by psychologists to help teachers instill responsibility and self-confidence in children. Following a brief overview of the HDP and explanation of the Magic…

  12. 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.

  13. Development of a force field for zeolitic imidazolate framework-8 with structural flexibility.

    PubMed

    Hu, Zhongqiao; Zhang, Liling; Jiang, Jianwen

    2012-06-28

    A force field is developed for zeolitic imidazolate framework-8 (ZIF-8) with structural flexibility by combining quantum chemical calculations and classical Amber force field. The predicted crystalline properties of ZIF-8 (lattice constants, bond lengths, angles, dihedrals, and x-ray diffraction patterns) agree well with experimental results. A structural transition from crystalline to amorphous as found in experiment is observed. The mechanical properties of ZIF-8 are also described fairly well by the force field, particularly the Young's modulus predicted matches perfectly with measured value. Furthermore, the heat capacity of ZIF-8 as a typical thermophysical property is predicted and close to experimental data available for other metal-organic frameworks. It is revealed the structural flexibility of ZIF-8 exerts a significant effect on gas diffusion. In rigid ZIF-8, no diffusive behavior is observed for CH(4) within the simulation time scale of current study. With the structural flexibility, however, the predicted diffusivities of CH(4) and CO(2) are close to reported data in the literature. The density distributions and free energy profiles of CH(4) and CO(2) in the pore of ZIF-8 are estimated to analyze the mechanism of gas diffusion. PMID:22755595

  14. Studies of the Retardation Force Developed on an Aircraft Tire Rolling in Slush or Water

    NASA Technical Reports Server (NTRS)

    Horne, Walter B.; Joyner, Upshur T.; Leland, Trafford J. W.

    1960-01-01

    A series of unbraked (freely rolling) taxi tests were conducted at the Langley landing-loads track with a 32 x 8.8, type 7, 22-ply-rating ribbed-tread aircraft tire to obtain data on tire retardation forces developed during rolling in both slush and water. The forward speeds of the tests ranged from 59 to 104 knots. Tire inflation pressures of 350 and 115 pounds per square inch were used. Results indicated a parabolic increase of retardation force with increasing forward velocity for both slush- and water-covered runway surfaces. The retardation force was found to increase approximately linearly with increasing water depth. Drag coefficients appropriate to the equations used are presented. Calculations made to determine the effect of slush on the take-off distance of a jet transport are in agreement with data obtained from an actual take-off in slush for this airplane. This is an interim report which deals with the effect of slush on the acceleration and the ground-run distance of airplanes during take-off.

  15. 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.

  16. 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.

  17. Development of an improved molecular dynamics force field for surface-adsorption simulations of molybdenum disulfide

    NASA Astrophysics Data System (ADS)

    Leuty, Gary; Berry, Rajiv; Muratore, Christopher; Varshney, Vikas; Turner, Heath

    Transition metal dichalcogenides (TMDs) such as molybdenum disulfide (MoS2) have garnered significant interest in recent years. With a layered structure similar to graphene, TMDs also have an intrinsic band gap. This band gap makes them an attractive alternative to graphene in many applications. MoS2 in particular has received attention due to the placement and tenability of its band gap, via functionalization, mechanical manipulation or physisorption. The latter of these is of interest in biosensor devices. Such applications are dependent on understanding physisorption on the MoS2 surface at the molecular level. This can be difficult experimentally but is possible via computer simulation techniques such as molecular dynamics (MD) simulations. MD simulations, however, require a force field accurate to the process modeled. Such a force field must correctly describe non-bonded interactions between substrate layers and between the surface and adsorbates. The force fields we are aware of have focused on intra-layer covalent bonding for structural and vibrational analysis. This work seeks to develop, through DFT and MD simulations with experimental characterization of surface adsorption, a more accurate parameterization for non-bonded interactions for MoS2.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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…

  4. Bengal Fan sediment transport activity and response to climate forcing inferred from sediment physical properties

    NASA Astrophysics Data System (ADS)

    Weber, M. E.; Wiedicke-Hombach, M.; Kudrass, H. R.; Erlenkeuser, H.

    2003-02-01

    We obtained sediment physical properties and geochemical data from 47 piston and gravity cores located in the Bay of Bengal, to study the complex history of the Late Pleistocene run-off from the Ganges and Brahmaputra rivers and its imprint on the Bengal Fan. Grain-size parameters were predicted from core logs of density and velocity to infer sediment transport energy and to distinguish different environments along the 3000-km-long transport path from the delta platform to the lower fan. On the shelf, 27 cores indicate rapidly prograding delta foresets today that contain primarily mud, whereas outer shelf sediment has 25% higher silt contents, indicative of stronger and more stable transport regime, which prevent deposition and expose a Late Pleistocene relic surface. Deposition is currently directed towards the shelf canyon 'Swatch of No Ground', where turbidites are released to the only channel-levee system that is active on the fan during the Holocene. Active growth of the channel-levee system occurred throughout sea-level rise and highstand with a distinct growth phase at the end of the Younger Dryas. Coarse-grained material bypasses the upper fan and upper parts of the middle fan, where particle flow is enhanced as a result of flow-restriction in well-defined channels. Sandier material is deposited mainly as sheet-flow deposits on turbidite-dominated plains at the lower fan. The currently most active part of the fan with 10-40-cm-thick turbidites is documented for the central channel including inner levees (e.g., site 40). Site 47 from the lower fan far to the east of the active channel-levee system indicates the end of turbidite sedimentation at 300 ka for that location. That time corresponds to the sea-level lowering during late isotopic stage 9 when sediment supply to the fan increased and led to channel avulsion farther upstream, probably indicating a close relation of climate variability and fan activity. Pelagic deep-sea sites 22 and 28 contain a 630

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

    PubMed

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

    2013-01-15

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

  6. Comparison of muscle force, muscle endurance, and electromyogram activity during an expedition at high altitude

    NASA Astrophysics Data System (ADS)

    Terasawa, K.; Fujiwara, T.; Sakai, A.; Yanagidaira, N.; Asano, K.; Yanagisawa, K.; Kashimura, N.; Ueda, G.; Wu, T.; Zhang, Y.

    1996-09-01

    Handgrip force (HF), maximal pinch force (MF), muscle endurance (ME), and the median power frequency (MdPF) of the activity shown in the electromyogram (EMG) were studied at various altitudes in eight normal healthy subjects. MF and ME were measured between the index finger and thumb, and all measurements were obtained at altitudes ranging from 610 to 4860 m during an expedition in the Qinghai Plateau in China. With the change in altitude HF, ME, and MF showed no significant change. Compared to the MdPF at 2260 m on ascent, the MdPF at other altitudes showed a significant decrease ( P<0.01). Thus, we conclude that muscle performance (HF, MF, and ME) was not affected by the environment at high altitude. However, MdPF was affected and the mean MdPF at 610 m after the expedition did not recover to initial values of MdPF. We suggest these results may have been affected by fatigue and chronic exposure to the hypobaric hypoxic environment, since the members of the expedition party expressed feelings of sluggishness and fatigue after the expedition.

  7. 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.

  8. [Effect of substances which change the proton-motive force on activity of methane microbe oxygenation].

    PubMed

    Malashenko, Iu P; Sokolov, I G; Rokitko, P V; Romanovskaia, V A

    2006-01-01

    High extracellular concentration of K+ stimulated methane oxygenation with Methylomonas rubra 15 [Russian character: see text], Methylococcus thermophilus 111 [Russian character: see text] and Methylococcus capsulatus 494 at neutral value of pH. That was determined by K+ arrival to the cells at neutral medium pH that resulted in the increase of pH difference between the exterior and interior sides of the membrane (ApH) and, respectively, in the increase of the methane oxygenation rate. Thus, methane monooxygenation depends on the availability of ion gradients on a membrane. Ionophores valinomycin and monensin inhibited methane oxygenation by the cells of Methylomonas rubra 15 [Russian character: see text] that evidenced for the methane oxygenation dependence on the protone-motive force which could be formed as the result both of protons displacement with oxygenation of methane monooxygenation products and of the gradient of potassium and sodium ions. Protonophore FCCP suppressed completely methane oxygenation in Methylococcus capsulatus 494 and M. thermophilus 111 [Russian character: see text] at neutral pH, and took no effect at the alkaline values of pH. This suggests that FCCP dissipates the proton-motive force and does not inhibit methane monooxygenase activity. The results obtained indicate that the process of methane oxygenation should be combined with energy generation in a form of the transmembrane electric charge (delta psi) and proton gradient (deltapH). PMID:17243361

  9. 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.

  10. 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.

  11. Capillary force lithography: the versatility of this facile approach in developing nanoscale applications

    NASA Astrophysics Data System (ADS)

    Ho, Dominic; Zou, Jianli; Zdyrko, Bogdan; Iyer, K. Swaminathan; Luzinov, Igor

    2014-12-01

    Since its inception as a simple, low cost alternative to more complicated lithographic techniques such as electron-beam and dip-pen lithography, capillary force lithography (CFL) has developed into a versatile tool to form sub-100 nm patterns. Utilizing the concept of a polymer melt, structures and devices generated by the technique have been used in applications varying from surfaces regulating cell growth to gas sensing. In this review, we discuss various CFL methodologies which have evolved, their application in both biological and non-biological research, and finally a brief outlook in areas of research where CFL is destined to make an enormous impact in the near future.

  12. Hybrid sounding rocket development at the United States Air Force Academy

    NASA Astrophysics Data System (ADS)

    Lydon, M. C.; Simmons, R. J.

    1993-06-01

    The United States Air Force Academy (USAFA) has developed a LOx-HTPB (Liquid Oxygen-Hydroxyl Terminated Polybutadiene) powered sounding rocket. USAFA has proven the use of hybrid rockets as a forgiving instrument to teach the fundamentals of aerospace system engineering at the undergraduate level. A rocket motor has been designed which will deliver 1000 lbs. of thrust for 1O-15 seconds and power the vehicle to approximately 20,000 ft. The rocket will be recovered via parachute and system performance will be recorded with an onboard data acquisition system. The main subsystems have been tested successfully and a launch is expected this summer.

  13. 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.

  14. 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

  15. 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. PMID:26207411

  16. Chemical activity induces dynamical force with global structure in a reaction-diffusion-convection system.

    PubMed

    Mahara, Hitoshi; Okada, Koichi; Nomura, Atsushi; Miike, Hidetoshi; Sakurai, Tatsunari

    2009-07-01

    We found a rotating global structure induced by the dynamical force of local chemical activity in a thin solution layer of excitable Belousov-Zhabotinsky reaction coupled with diffusion. The surface flow and deformation associated with chemical spiral waves (wavelength about 1 mm) represents a global unidirectional structure and a global tilt in the entire Petri dish (100 mm in diameter), respectively. For these observations, we scanned the condition of hierarchal pattern selection. From this result, the bromomalonic acid has an important role to induce the rotating global structure. An interaction between a reaction-diffusion process and a surface-tension-driven effect leads to such hierarchal pattern with different scales. PMID:19658764

  17. 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.

  18. 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

  19. 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.

  20. Active diffusion and microtubule-based transport oppose myosin forces to position organelles in cells.

    PubMed

    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

  1. 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.

  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. Development of a model ''use of intermediate force'' policy and training program for the Department of Energy

    SciTech Connect

    Glick, L.; Graves, B.; Leamons, T.

    1988-01-01

    The Department of Energy Central Training Academy has been tasked with the development of a model program to standardize general philosophy, policy, training curriculum, and use of intermediate force tools, equipment, and techniques by protective force personnel at Department of Energy contractor facilities. The paper encompasses applicable Department of Energy authority delineating protective force personnel duties, arrest and use of force authority and procedural guidelines, case law relevant to the use of less than lethal or intermediate force, recommended guidelines, and training and certification recommendations. Implementation of a standardized program for the Department of Energy will enhance the capability of protective force personnel to fulfill their varied and complex mission using only the minimum control necessary to ensure compliance with required procedures.

  4. Single Molecule Characterization of UV-Activated Antibodies on Gold by Atomic Force Microscopy.

    PubMed

    Funari, R; Della Ventura, B; Altucci, C; Offenhäusser, A; Mayer, D; Velotta, R

    2016-08-16

    The interaction between proteins and solid surfaces can influence their conformation and therefore also their activity and affinity. These interactions are highly specific for the respective combination of proteins and solids. Consequently, it is desirable to investigate the conformation of proteins on technical surfaces, ideally at single molecule level, and to correlate the results with their activity. This is in particular true for biosensors where the conformation-dependent target affinity of an immobilized receptor determines the sensitivity of the sensor. Here, we investigate for the first time the immobilization and orientation of antibodies (Abs) photoactivated by a photonic immobilization technique (PIT), which has previously demonstrated to enhance binding capabilities of antibody receptors. The photoactivated immunoglobulins are immobilized on ultrasmooth template stripped gold films and investigated by atomic force microscopy (AFM) at the level of individual molecules. The observed protein orientations are compared with results of nonactivated antibodies adsorbed on similar gold films and mica reference samples. We find that the behavior of Abs is similar for mica and gold when the protein are not treated (physisorption), whereas smaller contact area and larger heights are measured when Abs are treated (PIT). This is explained by assuming that the activated antibodies tend to be more upright compared with nonirradiated ones, thereby providing a better exposure of the binding sites. This finding matches the observed enhancement of Abs binding efficiency when PIT is used to functionalize gold surface of QCM-based biosensors. PMID:27444884

  5. Structure and activation dynamics of RBL-2H3 cells observed with scanning force microscopy.

    PubMed Central

    Braunstein, D; Spudich, A

    1994-01-01

    Surface and subsurface dynamics of Rat Basophilic Leukemia cells, a model system of stimulated secretion, were imaged using Scanning Force Microscopy (SFM) at a rate of 50-60 s/image. Cytoskeletal elements and organelles were tracked within quiescent cells and those activated after IgE receptor crosslinking. In addition, surface waves were observed moving within the plasma membrane. The structures seen in quiescent and activated cells can be correlated with those seen in electron micrographs and topographic SFM images of fixed detergent-extracted cells. Furthermore, images of the detergent-extracted nuclei reveal the presence of numerous nuclear pore complexes. High-magnification images of the nuclear pore complexes show evidence of subunit structure and exhibit dimensions consistent with those reported previously using electron microscopy. The behavior and overall change in morphology of cells observed during activation was consistent with that observed under similar conditions with Differential Interference Contrast microscopy. This study demonstrates that SFM, unlike other techniques, can be used to provide high-resolution information in both fixed and living cells. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 PMID:8061220

  6. 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. PMID:24962992

  7. Geothermal instrumentation development activities at Sandia

    SciTech Connect

    Carson, C.C.

    1985-03-01

    A major element of Sandia's Geothermal Technology Development Program is the effort directed toward development of instrumentation. This effort has two aspects, the development of high temperature components and prototype tools and the investigation of new concepts and capabilities. The focus of these activities is the acquisition of information to make geothermal drilling and resource development more efficient. Several projects of varying nature and scope make up the instrumentation development element, and this element will expand as the program emphasis on development of an advanced geothermal drilling system and the need for improved information grow. 13 refs.

  8. 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.

  9. Development of active vibration isolation system for precision machines

    NASA Astrophysics Data System (ADS)

    Li, H. Z.; Lin, W. J.; Yang, G. L.

    2009-12-01

    It is a common understanding by manufacturers of precision machines that vibrations are a potentially disastrous threat to precision and throughput. To satisfy the quest for more stable processes and tighter critical dimension control in the microelectronics manufacturing industry, active vibration control becomes increasingly important for high-precision equipment developers. This paper introduced the development of an active vibration isolation system for precision machines. Innovative mechatronic approaches are investigated that can effectively suppress both environmental and payload-generated vibration. In this system, accelerometers are used as the feedback sensor, voice coil motors are used to generate the counter force, and a TI DSP controller is used to couple sensor measurements to actuator forces via specially designed control algorithms in real-time to counteract the vibration disturbances. Experimental results by using the developed AVI prototype showed promising performance on vibration attenuation. It demonstrated a reduction of the settling time from 2s to 0.1s under impulsive disturbances; and a vibration attenuation level of more than 20dB for harmonic disturbances. The technology can be used to suppress vibration for a wide range of precision machines to achieve fast settling time and higher accuracy.

  10. Development of active vibration isolation system for precision machines

    NASA Astrophysics Data System (ADS)

    Li, H. Z.; Lin, W. J.; Yang, G. L.

    2010-03-01

    It is a common understanding by manufacturers of precision machines that vibrations are a potentially disastrous threat to precision and throughput. To satisfy the quest for more stable processes and tighter critical dimension control in the microelectronics manufacturing industry, active vibration control becomes increasingly important for high-precision equipment developers. This paper introduced the development of an active vibration isolation system for precision machines. Innovative mechatronic approaches are investigated that can effectively suppress both environmental and payload-generated vibration. In this system, accelerometers are used as the feedback sensor, voice coil motors are used to generate the counter force, and a TI DSP controller is used to couple sensor measurements to actuator forces via specially designed control algorithms in real-time to counteract the vibration disturbances. Experimental results by using the developed AVI prototype showed promising performance on vibration attenuation. It demonstrated a reduction of the settling time from 2s to 0.1s under impulsive disturbances; and a vibration attenuation level of more than 20dB for harmonic disturbances. The technology can be used to suppress vibration for a wide range of precision machines to achieve fast settling time and higher accuracy.

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

    PubMed

    Kang, Jong Ho; Park, Tae-Sung

    2015-09-01

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

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

    PubMed Central

    Kang, Jong Ho; Park, Tae-Sung

    2015-01-01

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

  13. A Forced Damped Oscillation Framework for Undulatory Swimming Provides New Insights into How Propulsion Arises in Active and Passive Swimming

    PubMed Central

    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. PMID:23785272

  14. 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

  15. 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…

  16. Development through Participation in Sociocultural Activity.

    ERIC Educational Resources Information Center

    Rogoff, Barbara; And Others

    1995-01-01

    Presents the theoretical position that as people participate in sociocultural activities, they contribute to the development of community practices that simultaneously contribute to the individuals' own development. Illustrates this argument using observations of the developmental processes of individual Girl Scouts and of community traditions of…

  17. 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

  18. Climatic Forcing of Intense North Atlantic Hurricane Activity over the Last Two Millennia (Invited)

    NASA Astrophysics Data System (ADS)

    Donnelly, J. P.; Lane, P.; Toomey, M.; Rodysill, J. R.; Hawkes, A. D.; van Henstum, P. J.; Wallace, D. J.; MacDonald, D.

    2013-12-01

    With a series of high-resolution reconstructions of hurricane-induced overwash from across the western North Atlantic we document patterns of event occurrence dating back more than 2000 years. The records suggest that while the frequency of hurricane landfall has not changed dramatically, the frequency of intense hurricanes has varied considerably. The sedimentary evidence indicates that the entire western North Atlantic experienced historically unprecedented levels of intense hurricane activity between 500 and 900 AD. This was likely forced by the relatively northern position of the intertropical convergence zone at this time resulting in more tropical cyclone genesis in the deep tropics, similar to what is seen in the modern climate during a positive Atlantic Meridional Mode, and La Niña-like conditions in the eastern tropical Pacific. Intense hurricane activity along the eastern seaboard of the United States was significantly reduced between 900 and 1400 AD when sea surface temperatures decreased in the western North Atlantic and El Niño-like conditions persisted in the eastern tropical Pacific. However, elevated intense tropical cyclone activity in the Gulf of Mexico continued through this interval, perhaps as a result of continued Loop Current penetration into the Gulf resulting in a deeper reservoir of warm water to fuel intense tropical cyclones. Intense tropical cyclone activity in the Gulf abruptly declined at 1400 AD as Loop Current penetration was reduced. However, the eastern seaboard of the United States experienced a period of elevated intense hurricane activity from 1400 to 1675 AD. This interval of increased intense hurricane activity had significant impacts on coastal landforms and ecosystems, including more frequent and widespread inlet formation, erosion of coastal marshes, and forest disturbance. Warming sea surface temperatures along the eastern seaboard of the United States at this time, related to more Gulf Stream transport and a reduction

  19. 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.

  20. Finite difference analysis for developing laminar flow in circular tubes applied to forced and combined convection

    NASA Astrophysics Data System (ADS)

    Collins, M. W.

    1980-03-01

    The complete two-dimensional partial differential equations for developing laminar flow in a circular tube have been treated by a finite difference analysis. Property variation with temperature, especially that of viscosity, is allowed for in a flexible manner. The continuity and momentum equations, and then the energy equations, are solved by direct elimination at each axial step, and a marching procedure used in the axial direction. The stepwise energy balance is rigidly satisfied throughout by using it as a constituent equation in place of the 'explicit' wall thermal boundary condition normally used. The analysis predicts the complete developing hydrodynamic and thermal fields, together with friction factors and heat transfer coefficients. It has been tested for a range of fluid velocity and thermal boundary conditions and for various fluids, including high viscosity oils, water and air. Predictions for constant wall temperature presented here are for forced and combined convection and are compared with experimental data of Test and Zeldin and Schmidt.

  1. 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)

  2. 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,…

  3. Forced expression of Hnf4a induces hepatic gene activation through directed differentiation.

    PubMed

    Yahoo, Neda; Pournasr, Behshad; Rostamzadeh, Jalal; Fathi, Fardin

    2016-08-01

    Embryonic stem (ES) cells are capable of unlimited self-renewal and have a diverse differentiation potential. These unique features make ES cells as an attractive source for developmental biology studies. Having the mature hepatocyte in the lab with functional activities is valuable in drug discovery studies. Overexpression of hepatocyte lineage-specific transcription factors (TFs) becomes a promising approach in pluripotent cell differentiation toward liver cells. Many studies generate transgenic ES cell lines to examine the effects of specific TFs overexpression in cell differentiation. In the present report, we have addressed whether a suspension or adherent model of differentiation is an appropriate way to study the role of Hnf4a overexpression. We generated ES cells that carried a doxycycline (Dox)-inducible Hnf4a using lentiviral vectors. The transduced cells were subjected to induced Hnf4a overexpression through both spontaneous and directed differentiation methods. Gene expression analysis showed substantially increased expression of hepatic gene markers, particularly Ttr and endogenous Hnf4a, in transduced cells differentiated by the directed approach. These results demonstrated that forced expression of TFs during directed differentiation would be an appropriate way to study relevant gene activation and the effects of overexpression in the context of hepatic differentiation. PMID:27233607

  4. Dynamic myosin activation promotes collective morphology and migration by locally balancing oppositional forces from surrounding tissue

    PubMed Central

    Aranjuez, George; Burtscher, Ashley; Sawant, Ketki; Majumder, Pralay; McDonald, Jocelyn A.

    2016-01-01

    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. PMID:27122602

  5. 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. PMID:27122602

  6. 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

  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. 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

  9. Influence of phosphate and pH on myofibrillar ATPase activity and force in skinned cardiac trabeculae from rat.

    PubMed Central

    Ebus, J P; Stienen, G J; Elzinga, G

    1994-01-01

    1. The effects of inorganic phosphate (Pi) and pH on maximal calcium-activated isometric force and MgATPase activity were studied in chemically skinned cardiac trabeculae from rat. ATP hydrolysis was coupled enzymatically to the breakdown of NADH, and its concentration was determined photometrically. Measurements were performed at 2.1 microns sarcomere length and 20 degrees C. ATPase activity and force were also determined when square-wave-shaped length changes were applied, with a frequency of 23 Hz and an amplitude of 2.5%. 2. At pH 7.0 without added Pi, the average isometric force (+/- S.E.M.) was 51 +/- 3 kN m-2 (n = 23). The average isometric ATPase activity was 0.43 +/- 0.02 mM s-1 (n = 23). During the changes in length ATPase activity increased to 152 +/- 3% of the isometric value, while the average force level decreased to 48 +/- 2%. 3. Isometric force gradually decreased to 31 +/- 2% of the control value when the Pi concentration was increased to 30 mM. Isometric ATPase activity, however, remained constant for Pi concentrations up to 5 mM and decreased to 87 +/- 3% at 30 mM Pi. When Pi accumulation inside the preparation due to ATP hydrolysis was taken into account, a linear relationship was found between isometric force and log [Pi]. The decrease in relative force was found to be 44 +/- 4% per decade. 4. During the length changes, ATPase activity and average force showed, apart from the increase in ATPase activity and decrease in average force, the same dependence on Pi as the isometric values. Stiffness, estimated from the amplitude of the force responses during the length changes, decreased in proportion to isometric force when the Pi concentration was increased. The changes in the shape of the force responses due to the repetitive changes in length as a function of the Pi concentration were relatively small. These results suggest that the effect of Pi on the transitions which influence ATP turnover is rather insensitive to changes in cross

  10. 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.

  11. Active induction of in vivo microbubbles by acoustic radiation force at the bifurcation of blood vessel and its evaluation.

    PubMed

    Masuda, Kohji; Koido, Jun; Miyazawa, Shinya; Wada, Hikaru; Hosaka, Naoto; Mochizuki, Takashi

    2015-08-01

    Alhough the development of drug delivery system using microbubbles and ultrasound is expected, because microbubbles diffuse in bloodstream, we have so far reported our attempts for active control of the microbubbles in flow by acoustic radiation force in order to increase local concentration of the microbubbles. However, there was no evidence that in vivo microbubbles act as similar as in vitro experiments, because there were limitations for reproduction of in vivo conditions. In this study, we have elucidated the relationship between brightness variation and microbubbles concentration in the suspension to estimate the absolute concentration in an invisible condition considering in vivo experiment. Then we conducted an experiment of active induction of microbubbles in a Y-form bifurcation of artificial blood vessel, where experimental conditions were with focused ultrasound, the central frequency of 5 MHz, flow velocity of 30 mm/s, and maximum sound pressure of 300 kPa-pp, respectively. Then we applied the conditions for active induction of in vivo microbubbles to compare with in vitro experiments. We used a bifurcation of blood vessel in an ear of a rabbit because the bifurcation shape in its blood vessel is visible. As the results of the experiment, the microbubbles concentration in the induced path was almost two times higher than that in the other path, which agrees with the results from in vitro experiments. PMID:26736523

  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. 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

    2015-05-01

    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. PMID:25870199

  14. Biomechanical forces promote blood development through prostaglandin E2 and the cAMP–PKA signaling axis

    PubMed Central

    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.

    2015-01-01

    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. PMID:25870199

  15. The importance of isometric maximum strength and peak rate-of-force development in sprint cycling.

    PubMed

    Stone, Michael H; Sands, William A; Carlock, Jon; Callan, Sam; Dickie, Des; Daigle, Karen; Cotton, John; Smith, Sarah L; Hartman, Michael

    2004-11-01

    This study was designed to investigate the relationship of whole-body maximum strength to variables potentially associated with track sprint-cycling success. These variables included body composition, power measures, coach's rank, and sprint-cycling times. The study was carried out in 2 parts. The first part (n = 30) served as a pilot for the second part (n = 20). Subjects for both parts ranged from international-caliber sprint cyclists to local-level cyclists. Maximum strength was measured using an isometric midthigh pull (IPF). Explosive strength was measured as the peak rate-of-force development (IPRFD) from the isometric force-time curve. Peak power was estimated from countermovement (CMJPP) and static vertical jumps (SJPP) and measured by modified Wingate tests. Athletes were ranked by the U.S. national cycling coach (part 1). Sprint times (from a standing start) were measured using timing gates placed at 25, 82.5, 165, 247.5, and 330 m of an outdoor velodrome (part 2). Maximum strength (both absolute and body-mass corrected) and explosive strength were shown to be strongly correlated with jump and Wingate power. Additionally, maximum strength was strongly correlated with both coach's rank (parts 1 and 2) and sprint cycling times (part 2). The results suggest that larger, stronger sprint cyclists have an advantage in producing power and are generally faster sprint cyclists. PMID:15574097

  16. Structural Survey of Zinc Containing Proteins and the Development of the Zinc AMBER Force Field (ZAFF)

    PubMed Central

    Peters, Martin B.; Yang, Yue; Wang, Bing; Füsti-Molnár, László; Weaver, Michael N.; Merz, Kenneth M.

    2010-01-01

    Currently the Protein Data Bank (PDB) contains over 18,000 structures that contain a metal ion including Na, Mg, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pd, Ag, Cd, Ir, Pt, Au, and Hg. In general, carrying out classical molecular dynamics (MD) simulations of metalloproteins is a convoluted and time consuming process. Herein, we describe MCPB (Metal Center Parameter Builder), which allows one, to conveniently and rapidly incorporate metal ions using the bonded plus electrostatics model (Hoops et al., J. Am. Chem. Soc. 1991, 113, 8262–8270) into the AMBER Force Field (FF). MCPB was used to develop a Zinc FF, ZAFF, which is compatible with the existing AMBER FFs. The PDB was mined for all Zn containing structures with most being tetrahedrally bound. The most abundant primary shell ligand combinations were extracted and FFs were created. These include Zn bound to CCCC, CCCH, CCHH, CHHH, HHHH, HHHO, HHOO, HOOO, HHHD, and HHDD (O = water and the remaining are 1 letter amino acid codes). Bond and angle force constants and RESP charges were obtained from B3LYP/6-31G* calculations of model structures from the various primary shell combinations. MCPB and ZAFF can be used to create FFs for MD simulations of metalloproteins to study enzyme catalysis, drug design and metalloprotein crystal refinement. PMID:20856692

  17. Forced degradation of nepafenac: Development and validation of stability indicating UHPLC method.

    PubMed

    Runje, Mislav; Babić, Sandra; Meštrović, Ernest; Nekola, Irena; Dujmić-Vučinić, Željka; Vojčić, Nina

    2016-05-10

    This paper presents stability study of the nonsteroidal anti-inflammatory drug (NSAID) nepafenac. In order to investigate stability of nepafenac, it was subjected to forced degradation under different stress conditions: acid and base hydrolysis, oxidation, humidity, heat and light. A novel stability indicating reverse phase ultra high performance liquid chromatographic (UHPLC) method coupled to ultraviolet detector has been developed to separate nepafenac and all related compounds (2-aminobenzophenone, Cl-thionepafenac, thionepafenac, Cl-nepafenac, hydroxy-nepafenac, and cyclic-nepafenac). Efficient chromatographic separation was achieved on a Waters Acquity BEH C18 stationary phase with a gradient elution. Quantification was carried out at 235 nm at a flow rate of 0.6 mL/min(-1). The resolution between nepafenac and six potential impurities is found to be greater than 2.0. The developed method was validated with respect to specificity, LOD, LOQ, linearity, precision, accuracy and robustness. The r(2) values for nepafenac and six potential impurities were all greater than 0.999. The developed method is capable to detect impurities of nepafenac at a level of 0.005% with respect to test concentration of 1.0mg/mL. Significant degradation is observed in acid, base and oxidative degradation conditions and degradation products (DPs) were identified using mass spectrometry analysis; two of them were found to be a known process related impurities (hydroxy- and cyclic-nepafenac) whereas four degradation products were identified as new degradation impurities. The forced degradation samples were assayed against a qualified reference standard and the mass balance was found to be close to 99.5%. PMID:26871279

  18. Control of transient vibrations due to stage movements in 6-dof active pneumatic table by inertial force compensation

    NASA Astrophysics Data System (ADS)

    Sun, Jong-Oh; Kim, Kwang-joon

    2013-10-01

    Passive pneumatic tables are popularly used in precision measurements or processes for isolation of ground vibrations over frequency ranges higher than resonance frequencies of a few Hz typically. Recently, active pneumatic tables are also used often because the passive systems are liable to table excitations in the low resonance frequency ranges, causing long settling times. In studies on the active tables, disturbances onto the tables were often regarded to be unknown and, hence, feedback control algorithms were implemented. However, the disturbances are mostly due to inertial forces due to movement of equipment on the table, e.g., x-y stages. Such a movement is given relative to the table as command inputs. Since absolute motion of the table is normally measured in an active isolation table, absolute motion of the equipment can be easily estimated for calculation of the inertial force exerted onto the table by the moving equipment. Consequently, by compensating dynamic pressure inside the pneumatic chamber to counteract with the inertia force due to the equipment motion, resultant forces acting onto the table can be made zero. In this paper, how to apply the proposed feed-forward control algorithm to a 6-degree of freedom active pneumatic table with time-delay pneumatic control is presented. Performance of the inertial force compensation control evaluated through experiments is also discussed.

  19. 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…

  20. Towards the development of a novel experimental shoulder simulator with rotating scapula and individually controlled muscle forces simulating the rotator cuff.

    PubMed

    Baumgartner, Daniel; Tomas, Daniel; Gossweiler, Lukas; Siegl, Walter; Osterhoff, Georg; Heinlein, Bernd

    2014-03-01

    A preclinical analysis of novel implants used in shoulder surgery requires biomechanical testing conditions close to physiology. Existing shoulder experiments may only partially apply multiple cycles to simulate postoperative, repetitive loading tasks. The aim of the present study was therefore the development of an experimental shoulder simulator with rotating scapula able to perform multiple humeral movement cycles by simulating individual muscles attached to the rotator cuff. A free-hanging, metallic humerus pivoted in a polyethylene glenoid is activated by tension forces of linear electroactuators to simulate muscles of the deltoideus (DELT), supraspinatus (SSP), infraspinatus/teres minor and subscapularis. The abductors DELT and SSP apply forces with a ratio of 3:1 up to an abduction angle of 85°. The rotating scapular part driven by a rotative electro actuator provides one-third to the overall arm abduction. Resulting joint forces and moments are measured by a 6-axis load cell. A linear increase in the DELT and SSP motors is shown up to a maximum of 150 and 50 N for the DELT and SSP, respectively. The force vector in the glenoid resulted in 253 N at the maximum abduction. The present investigation shows the contribution of individual muscle forces attached to the moving humerus to perform active abduction in order to reproducibly test shoulder implants. PMID:24170552

  1. 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.

  2. 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

  3. Testing Done for Lorentz Force Accelerators and Electrodeless Propulsion Technology Development

    NASA Technical Reports Server (NTRS)

    Pencil, Eric J.; Gilland, James H.; Arrington, Lynn A.; Kamhawi, Hani

    2004-01-01

    The NASA Glenn Research Center is developing Lorentz force accelerators and electrodeless plasma propulsion for a wide variety of space applications. These applications range from precision control of formation-flying spacecraft to primary propulsion for very high power interplanetary spacecraft. The specific thruster technologies being addressed are pulsed plasma thrusters, magnetoplasmadynamic thrusters, and helicon-electron cyclotron resonance acceleration thrusters. The pulsed plasma thruster mounted on the Earth Observing-1 spacecraft was operated successfully in orbit in 2002. The two-axis thruster system is fully incorporated in the attitude determination and control system and is being used to automatically counteract disturbances in the pitch axis of the spacecraft. Recent on-orbit operations have focused on extended operations to add flight operation time to the total accumulated thruster life. The results of the experiments pave the way for electric propulsion applications on future Earth-imaging satellites.

  4. Assessment of split-charge equilibration model for development of polarizable force fields

    NASA Astrophysics Data System (ADS)

    Smirnov, Konstantin S.

    2015-10-01

    Performance of split-charge equilibration model (SQE) for force field development was tested by computing static and response characteristics of water clusters. Results of the study show that SQE yields reliable results for the molecular electrostatic potential, dipole, and polarizability of clusters of increasing size. Intermolecular charge transfer needs to be considered for hydrogen bonded systems in order to accurately reproduce the dipole versus system size behavior. It was found that the model quantitatively mimics the IR intensities of intermolecular vibrational modes, but fails in the computation of the IR and Raman intensities of intramolecular vibrations. The response of charge distribution to perturbation by point charge is confidently modeled by SQE in the conditions corresponding to the linear-response regime.

  5. Development of a Lorentz Force Accelerator Injector for the VASIMR Engine

    NASA Astrophysics Data System (ADS)

    Glover, T. W.; Chan, A. A.; Díaz, F. R. Chang; Squire, J.

    1998-11-01

    We report on the effort to develop a Lorentz Force Accelerator for use as a plasma injector for the VASIMR(Variable Specific Impulse Magnetoplasma Rocket) engine. Advantages of the LFA, also known as a magnetoplasmadynamic thruster, include simplicity of construction, the ability to use a wide variety of propellant gases without modification, and minimal power processing requirements. As a plasma source for the VASIMR engine, its feature of ejecting plasma in a tightly collimated jet allows it to inject plasma through the loss cone of the VASIMR magnetic field into the engine's central cell. This passage from weak to strong magnetic field regions may result in a desirable increase in plasma density in the central cell. Work to date has focused on achieving reliable start-up and steady-state operation.

  6. Field evidence of the viscous sublayer in a tidally forced developing boundary layer

    NASA Astrophysics Data System (ADS)

    Wengrove, M. E.; Foster, D. L.

    2014-07-01

    Field observations of boundary layer development within a tidally forced estuary revealed evidence of an observable viscous sublayer. Evidence is provided by several independent measures of the flow field, including hydrodynamic smoothness, an immobile bed, and characteristic velocity, constant stress, and higher-order moment structures. This investigation reports what may be the second comprehensive observation of the viscous sublayer in a marine environment, and what could be the first observation of a momentum balance that includes the viscous sublayer within a shallow estuarine environment. Hydrodynamic observations were made in a straight channel within the Great Bay Estuary of New Hampshire over a flat sandy mud with low water depth of 1.5 m at the sampling location. Beyond quantifying the role of the benthic boundary layer in nutrient dynamics, these observations are useful to provide insight into very near boundary stress estimates leading to incipient motion in estuarine and coastal environments.

  7. 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

  8. Fluid flows and forces in development: functions, features and biophysical principles

    PubMed Central

    Freund, Jonathan B.; Goetz, Jacky G.; Hill, Kent L.; Vermot, Julien

    2012-01-01

    Throughout morphogenesis, cells experience intracellular tensile and contractile forces on microscopic scales. Cells also experience extracellular forces, such as static forces mediated by the extracellular matrix and forces resulting from microscopic fluid flow. Although the biological ramifications of static forces have received much attention, little is known about the roles of fluid flows and forces during embryogenesis. Here, we focus on the microfluidic forces generated by cilia-driven fluid flow and heart-driven hemodynamics, as well as on the signaling pathways involved in flow sensing. We discuss recent studies that describe the functions and the biomechanical features of these fluid flows. These insights suggest that biological flow determines many aspects of cell behavior and identity through a specific set of physical stimuli and signaling pathways. PMID:22395739

  9. Development of a three dimensional scanning touch probe with high precision and low contact force

    NASA Astrophysics Data System (ADS)

    Chu, Chih-Liang; Ke, Jhih-Sian; Chen, Hung-Chi

    2013-01-01

    This study aims to develop a three dimensional scanning touch probe with high precision and low contact force. The overall design has two parts, mechanism design and optical path design. The mechanism design contains three parts, Zaxis system, XY-axis system, and probe mechanism. The Z-axis system applies the characteristic of the thin sheet spring to move vertically. In the design of XY-axis system, a micro-beam is employed, through which length, width, thickness of the micro-beam and corresponding dimensions of the leaf spring are designed according to the selected contact force. The freedom degree is limited to three. And the center of the mechanism is equipped with a stylus to inhibit displacement of the Z-axis. The contact between the probe and the workpiece only leads to change in the angles of Xand Y-axes, achieving the feature of 2-degree freedom. To enable rapid change for the probes, this study designs a probe mechanism, reliability of which is analyzed and validated with ANSYS software, so that the design of 3-degree freedom mechanism is completed. The sensor has a laser diode to coordinate with Position Sensor Detector (PSD) which works with the optical path designed to measure placement of Z-axis and angle placement of XY-axis. By validation through an experiment, the three dimensional scanning touch probe developed by this study has a measuring range of +/-1mm×+/-1mm×1mm, and unidirectional repeatability of 0.6um.

  10. 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. PMID:25296716

  11. [Global and historical development of the IMETAF (International Molecular Epidemiology Task Force) in Mexico].

    PubMed

    Gorodezky, C

    1997-01-01

    IMETAF or International Molecular Epidemiology Task Force was created upon the enthusiasm of Janice Dorman, molecular epidemiologist at Pittsburgh University. Also, she was in charge of the WHO type I Diabetes world project called DIAMOND. As a result of this project done with Mexican scientists. The Scientific Committee of IMETAF was formed on July 28, 1993. The activities began. A national infrastructure survey was done to analyze the epidemiology and molecular biology capabilities; a directory of scientist in epidemiology and molecular biology was elaborated; a theoric and practical course on molecular epidemiology was organized during 1996 and a second one will be held in 1997; and a series of Workshops were done: cancer and leukemias; bacterial diseases; trypanosomiosis and leishmaniosis and viral diseases. The results of these academic activities were brought to the National Academy of Medicine to a 2 days workshop and to an International Symposium called Projection of molecular epidemiology in medicine, held on April 17, 1996. The papers are published in this number. The goal of IMETAF will continue promoting transfer of technology, stimulating formal training in molecular epidemiology and helping getting funds for collaborative projects. PMID:9504097

  12. Kelvin probe force microscopy for local characterisation of active nanoelectronic devices.

    PubMed

    Wagner, Tino; Beyer, Hannes; Reissner, Patrick; Mensch, Philipp; Riel, Heike; Gotsmann, Bernd; Stemmer, Andreas

    2015-01-01

    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

  13. 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

  14. 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. PMID:24428536

  15. 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.

  16. 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…

  17. Tensile force on human macrophage cells promotes osteoclastogenesis through receptor activator of nuclear factor κB ligand induction.

    PubMed

    Kao, Chia-Tze; Huang, Tsui-Hsien; Fang, Hsin-Yuan; Chen, Yi-Wen; Chien, Chien-Fang; Shie, Ming-You; Yeh, Chia-Hung

    2016-07-01

    Little is known about the effects of tensile forces on osteoclastogenesis by human monocytes in the absence of mechanosensitive cells, including osteoblasts and fibroblasts. In this study we consider the effects of tensile force on osteoclastogenesis in human monocytes. The cells were treated with receptor activator of nuclear factor κB ligand (RANKL) to promote osteoclastogenesis. Then,expression and secretion of cathepsin K were examined. RANKL and the formation of osteoclasts during the osteoclast differentiation process under continual tensile stress were evaluated by Western blot. It was also found that -100 kPa or lower induces RANKL-enhanced tartrate-resistant acid phosphatase activity in a dose-dependent manner. Furthermore, an increased tensile force raises the expression and secretion of cathepsin K elevated by RANKL, and is concurrent with the increase of TNF-receptor-associated factor 6 induction and nuclear factor κB activation. Overall, the current report demonstrates that tensile force reinforces RANKL-induced osteoclastogenesis by retarding osteoclast differentiation. The tensile force is able to modify every cell through dose-dependent in vitro RANKL-mediated osteoclastogenesis, affecting the fusion of preosteoclasts and function of osteoclasts. However, tensile force increased TNF-receptor-associated factor 6 expression. These results are in vitro findings and were obtained under a condition of tensile force. The current results help us to better understand the cellular roles of human macrophage populations in osteoclastogenesis as well as in alveolar bone remodeling when there is tensile stress. PMID:26204845

  18. 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.

  19. 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.

  20. 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…

  1. 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…

  2. 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.…

  3. 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…

  4. SKILL DEVELOPMENT THROUGH GAMES AND RHYTHMIC ACTIVITIES.

    ERIC Educational Resources Information Center

    NAGEL, CHARLES; MOORE, FREDRICKA

    A DISCUSSION OF THE OVERALL OBJECTIVES OF PHYSICAL ACTIVITIES IN THE ELEMENTARY SCHOOL, THE PURPOSES OF DEVELOPING MOVEMENT SKILLS IN GAMES AND RHYTHMS, AND THE ROLE OF THE TEACHER IN PHYSICAL EDUCATION COMPRISES THE INTRODUCTORY CHAPTER OF THIS TEXTBOOK FOR BEGINNING PHYSICAL EDUCATION TEACHERS. SUCCEEDING CHAPTERS ARE CONCERNED WITH FIVE…

  5. Interactive Video Training and Development Activity.

    ERIC Educational Resources Information Center

    Troy State Univ., AL.

    The Interactive Video Training and Development Activity of Troy State University (Troy, Alabama) is described in this report. The project has trained more than 30 people in the production of interactive video programs since its inception in 1983. Since 1985, training programs have been offered twice a year to individuals within and outside the…

  6. 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.

  7. The ReaxFF reactive force-field: Development, applications, and future directions

    DOE PAGESBeta

    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; et al

    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

  8. Passive scalar entrainment and mixing in a forced, spatially-developing mixing layer

    NASA Technical Reports Server (NTRS)

    Lowery, P. S.; Reynolds, W. C.; Mansour, N. N.

    1987-01-01

    Numerical simulations are performed for the forced, spatially-developing plane mixing layer in two and three dimensions. Transport of a passive scalar field is included in the computation. This, together with the allowance for spatial development in the simulations, affords the opportunity for study of the asymmetric entrainment of irrotational fluid into the layer. The inclusion of a passive scalar field provides a means for simulating the effect of this entrainment asymmetry on the generation of 'products' from a 'fast' chemical reaction. Further, the three-dimensional simulations provide useful insight into the effect of streamwise structures on these entrainment and 'fast' reaction processes. Results from a two-dimensional simulation indicate 1.22 parts high-speed fluid are entrained for every one part low-speed fluid. Inclusion of streamwise vortices at the inlet plane of a three-dimensional simulation indicate a further increase in asymmetric entrainment - 1.44:1. Results from a final three-dimensional simulation are presented. In this case, a random velocity perturbation is imposed at the inlet plane. The results indicate the 'natural' development of the large spanwise structures characteristic of the mixing layer.

  9. A Micro-Fabricated Force Sensor Using an All Thin Film Piezoelectric Active Sensor

    PubMed Central

    Lee, Junwoo; Choi, Wook; Yoo, Yong Kyoung; Hwang, Kyo Seon; Lee, Sang-Myung; Kang, Sungchul; Kim, Jinseok; Lee, Jeong Hoon

    2014-01-01

    The ability to measure pressure and force is essential in biomedical applications such as minimally invasive surgery (MIS) and palpation for detecting cancer cysts. Here, we report a force sensor for measuring a shear and normal force by combining an arrayed piezoelectric sensors layer with a precut glass top plate connected by four stress concentrating legs. We designed and fabricated a thin film piezoelectric force sensor and proposed an enhanced sensing tool to be used for analyzing gentle touches without the external voltage source used in FET sensors. Both the linear sensor response from 3 kPa to 30 kPa and the exact signal responses from the moving direction illustrate the strong feasibility of the described thin film miniaturized piezoelectric force sensor. PMID:25429407

  10. A micro-fabricated force sensor using an all thin film piezoelectric active sensor.

    PubMed

    Lee, Junwoo; Choi, Wook; Yoo, Yong Kyoung; Hwang, Kyo Seon; Lee, Sang-Myung; Kang, Sungchul; Kim, Jinseok; Lee, Jeong Hoon

    2014-01-01

    The ability to measure pressure and force is essential in biomedical applications such as minimally invasive surgery (MIS) and palpation for detecting cancer cysts. Here, we report a force sensor for measuring a shear and normal force by combining an arrayed piezoelectric sensors layer with a precut glass top plate connected by four stress concentrating legs. We designed and fabricated a thin film piezoelectric force sensor and proposed an enhanced sensing tool to be used for analyzing gentle touches without the external voltage source used in FET sensors. Both the linear sensor response from 3 kPa to 30 kPa and the exact signal responses from the moving direction illustrate the strong feasibility of the described thin film miniaturized piezoelectric force sensor. PMID:25429407

  11. High temperature solid oxide fuel development activities

    SciTech Connect

    Ray, E.R.

    1993-11-01

    This paper presents an overview of the Westinghouse tubular SOFC development activities and current program status. Goal is to develop a cell that can operate for 50,000 to 100,000 h. Test results are presented for multiple single cell tests which have now successfully exceeded 40,000 hours of continuous power operation at temperature. Two 25-kW SOFC customer tests units were delivered in 1992; a 20-kW SOFC system is bein manufactured and will be operated by Southern California Edison in 1995. Megawatt class generators are being developed.

  12. Pedunculopontine Gamma Band Activity and Development

    PubMed Central

    Garcia-Rill, Edgar; Luster, Brennon; Mahaffey, Susan; MacNicol, Melanie; Hyde, James R.; D’Onofrio, Stasia M.; Phillips, Cristy

    2015-01-01

    This review highlights the most important discovery in the reticular activating system in the last 10 years, the manifestation of gamma band activity in cells of the reticular activating system (RAS), especially in the pedunculopontine nucleus, which is in charge of waking and rapid eye movement (REM) sleep. The identification of different cell groups manifesting P/Q-type Ca2+ channels that control waking vs. those that manifest N-type channels that control REM sleep provides novel avenues for the differential control of waking vs. REM sleep. Recent discoveries on the development of this system can help explain the developmental decrease in REM sleep and the basic rest-activity cycle. PMID:26633526

  13. Pedunculopontine Gamma Band Activity and Development.

    PubMed

    Garcia-Rill, Edgar; Luster, Brennon; Mahaffey, Susan; MacNicol, Melanie; Hyde, James R; D'Onofrio, Stasia M; Phillips, Cristy

    2015-01-01

    This review highlights the most important discovery in the reticular activating system in the last 10 years, the manifestation of gamma band activity in cells of the reticular activating system (RAS), especially in the pedunculopontine nucleus, which is in charge of waking and rapid eye movement (REM) sleep. The identification of different cell groups manifesting P/Q-type Ca(2+) channels that control waking vs. those that manifest N-type channels that control REM sleep provides novel avenues for the differential control of waking vs. REM sleep. Recent discoveries on the development of this system can help explain the developmental decrease in REM sleep and the basic rest-activity cycle. PMID:26633526

  14. Development of a precision indentation and scratching system with a tool force and displacement control module

    NASA Astrophysics Data System (ADS)

    Park, Jae-jun; Kwon, Kihwan; Bang, Jinhyeok; Cho, Nahmgyoo; Han, Chang-soo; Choi, Nak-sam

    2007-04-01

    This article presents a tip-based micropatterning system with a precision device for measuring the machine force and the tool path. The machine force is obtained by a tool control module with a leaf spring and a capacitive displacement sensor. It is controlled to provide a force that ranges from 80 μN to 8 N. The force sensing unit, which is part of the module, is mounted on a PZT (PbZrTi) driven in-feed motion stage with a resolution of 1 nm. The work piece is set on an X-Y motion stage, and the position can be controlled with a tool path accuracy of 5 nm. Micropatterning and precision indentation experiments were performed, while the machined surfaces were examined by atomic force microscopy. From these results, the feasibility of the system for precise force-displacement control was verified for application in tip-based precision machining.

  15. Fluvial islands: First stage of development from nonmigrating (forced) bars and woody-vegetation interactions

    NASA Astrophysics Data System (ADS)

    Wintenberger, Coraline L.; Rodrigues, Stéphane; Bréhéret, Jean-Gabriel; Villar, Marc

    2015-10-01

    Fluvial islands can develop from the channel bed by interactions between pioneer trees and bars. Although vegetation recruitment and survival is possible on all bar types, it is easier for trees to survive on nonmigrating bars developed from a change in channel geometry or to the presence of a steady perturbation. This field study details the first stages of development of a vegetated mid-channel, nonmigrating (or forced) bar and its evolution toward an island form. Over six years, analysis of bed topographical changes, vegetation density and roughness, scour and fill depths, sediment grain size and architecture, and excess bed shear stress highlighted a specific signature of trees on topography and grain size segregation. Two depositional processes combining the formation of obstacle marks and upstream-shifting deposition of sediments led to the vertical accretion of the vegetated bar. During the first stage of the bar accretion, bedload sediment supply coming from surrounding channels during floods was identified as a key process modulated by the presence of woody vegetation and a deflection effect induced by the preexisting topography. Grain size segregation between vegetated and bare areas was also highlighted and interpreted as an important process affecting the development of surrounding channels and the degree of disconnection (and hence the speed of development) of a growing island. The heterogeneity of bedload supply can explain why sediment deposition and density of trees are not strictly related. A general conceptual model detailing the first stages of evolution from a bar to an established island is proposed for relatively large lowland rivers.

  16. 76 FR 39392 - Record of Decision for the F-35 Force Development Evaluation and Weapons School Beddown, Nellis...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-06

    ...On June 24, 2011, the United States Air Force signed the ROD for the F-35 Force Development Evaluation (FDE) and Weapons School (WS) Beddown, Nellis AFB, Nevada. The decision was based on matters discussed in the Final Environmental Impact Statement (EIS), inputs from the public and regulatory agencies, and other relevant factors. The Final EIS was made available to the public on May 13, 2011,......

  17. Force interaction of high pressure glow discharge with fluid flow for active separation control

    SciTech Connect

    Roy, Subrata; Gaitonde, Datta V.

    2006-02-15

    Radio frequency based discharges at atmospheric pressures are the focus of increased interest in aerodynamics because of the wide range of potential applications including, specifically, actuation in flows at moderate speeds. Recent literature describing promising experimental observations, especially on separation control, has spurred efforts in the development of parallel theoretical modeling to lift limitations in the current understanding of the actuation mechanism. The present effort demonstrates higher fidelity first-principle models in a multidimensional finite-element framework to predict surface discharge-induced momentum exchange. The complete problem of a dielectric barrier discharge at high pressure with axially displaced electrodes is simulated in a self-consistent manner. Model predictions for charge densities, the electric field, and gas velocity distributions are shown to mimic trends reported in the experimental literature. Results show that a residual of electrons remains deposited on the dielectric surface downstream of the exposed powered electrode for the entire duration of the cycle and causes a net electric force in the direction from the electrode to the downstream surface. For the first time, results document the mitigation process of a separation bubble formed due to flow past a flat plate inclined at 12 degree sign angle of attack. This effort sets the basis for extending the formulation further to include polyphase power input in multidimensional settings, and to apply the simulation method to flows past common aerodynamic configurations.

  18. 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…

  19. 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.

  20. Toward Hybrid Position/Force Control for an Active Handheld Micromanipulator

    PubMed Central

    Wells, Trent S.; MacLachlan, Robert A.; Riviere, Cameron N.

    2014-01-01

    Vitreoretinal microsurgery requires precise hand-eye coordination to manipulate delicate structures within the eye on the order of tens of microns. To achieve these tasks, surgeons use tools of diameter 0.9 mm or less to access the eye’s interior structures. The level of force required during these manipulations is often below the human tactile threshold, requiring the surgeon to rely on subtle visual cues or to apply larger forces above the tactile threshold for feedback. However, both of these methods can lead to tissue damage. Excursions can be made into tissues which are not felt by the surgeon, while larger forces have a higher chance of damaging tissue within the eye. To prevent damage to the retina and other anatomy, we present the implementation of hybrid position/force control operating in the sub-tactile force range for a handheld robotic system. This approach resulted in a 42% reduction in the mean force and 52% reduction in maximum force during peeling tasks. PMID:26405560

  1. Muscle activity pattern dependent pain development and alleviation.

    PubMed

    Sjøgaard, Gisela; Søgaard, Karen

    2014-12-01

    Muscle activity is for decades considered to provide health benefits irrespectively of the muscle activity pattern performed and whether it is during e.g. sports, transportation, or occupational work tasks. Accordingly, the international recommendations for public health-promoting physical activity do not distinguish between occupational and leisure time physical activity. However, in this body of literature, attention has not been paid to the extensive documentation on occupational physical activity imposing a risk of impairment of health - in particular musculoskeletal health in terms of muscle pain. Focusing on muscle activity patterns and musculoskeletal health it is pertinent to elucidate the more specific aspects regarding exposure profiles and body regional pain. Static sustained muscle contraction for prolonged periods often occurs in the neck/shoulder area during occupational tasks and may underlie muscle pain development in spite of rather low relative muscle load. Causal mechanisms include a stereotype recruitment of low threshold motor units (activating type 1 muscle fibers) characterized by a lack of temporal as well as spatial variation in recruitment. In contrast during physical activities at leisure and sport the motor recruitment patterns are more dynamic including regularly relatively high muscle forces - also activating type 2 muscles fibers - as well as periods of full relaxation even of the type 1 muscle fibers. Such activity is unrelated to muscle pain development if adequate recovery is granted. However, delayed muscle soreness may develop following intensive eccentric muscle activity (e.g. down-hill skiing) with peak pain levels in thigh muscles 1-2 days after the exercise bout and a total recovery within 1 week. This acute pain profile is in contrast to the chronic muscle pain profile related to repetitive monotonous work tasks. The painful muscles show adverse functional, morphological, hormonal, as well as metabolic characteristics. Of

  2. 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.

  3. 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.

  4. Development of a CFD Code for Analysis of Fluid Dynamic Forces in Seals

    NASA Technical Reports Server (NTRS)

    Athavale, Mahesh M.; Przekwas, Andrzej J.; Singhal, Ashok K.

    1991-01-01

    The aim is to develop a 3-D computational fluid dynamics (CFD) code for the analysis of fluid flow in cylindrical seals and evaluation of the dynamic forces on the seals. This code is expected to serve as a scientific tool for detailed flow analysis as well as a check for the accuracy of the 2D industrial codes. The features necessary in the CFD code are outlined. The initial focus was to develop or modify and implement new techniques and physical models. These include collocated grid formulation, rotating coordinate frames and moving grid formulation. Other advanced numerical techniques include higher order spatial and temporal differencing and an efficient linear equation solver. These techniques were implemented in a 2D flow solver for initial testing. Several benchmark test cases were computed using the 2D code, and the results of these were compared to analytical solutions or experimental data to check the accuracy. Tests presented here include planar wedge flow, flow due to an enclosed rotor, and flow in a 2D seal with a whirling rotor. Comparisons between numerical and experimental results for an annular seal and a 7-cavity labyrinth seal are also included.

  5. Development of a Hybrid Atomic Force Microscopic Measurement System Combined with White Light Scanning Interferometry

    PubMed Central

    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. PMID:22368463

  6. 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. PMID:22368463

  7. Hydrothermal research and development assessment. Task force report: projections for electric systems

    SciTech Connect

    Not Available

    1982-05-01

    It is estimated that high temperature (greater than 150/sup 0/C or 300/sup 0/F) hydrothermal resources in the western United States have the potential for producing about 140,000 megawatts of electric power for 30 years. The objectives of the present analysis were to realistically evaluate the extent to which these resources might be utilized over the next 20 years, and to assess the probably impact of Federal programs on that utilization. The R and D assessment team interviewed industry personnel to determine the nature and the relative significance of investment decision criteria for developers and utilities. The results of these interviews were used to develop a probabilistic model to simulate the investment decision behavior of these two groups toward hydrothermal resources. Estimations of the characteristics of anticipated available resources (e.g., temperature, salinity, depth) and predictions of the geographic distribution of new resource discoveries were based upon the characteristics and distribution of known reservoirs. The impact of a minimal R and D program and the impact of expanded R and D program were estimated on the basis of its effect upon industry investment decision criteria (e.g., the cost of power). The Task Force estimates comparing three different scenarios: (1) no program, (2) minimal R and D, and (3) expanded R and D are presented.

  8. Force sensor

    DOEpatents

    Grahn, Allen R.

    1993-01-01

    A force sensor and related method for determining force components. The force sensor includes a deformable medium having a contact surface against which a force can be applied, a signal generator for generating signals that travel through the deformable medium to the contact surface, a signal receptor for receiving the signal reflected from the contact surface, a generation controller, a reception controller, and a force determination apparatus. The signal generator has one or more signal generation regions for generating the signals. The generation controller selects and activates the signal generation regions. The signal receptor has one or more signal reception regions for receiving signals and for generating detections signals in response thereto. The reception controller selects signal reception regions and detects the detection signals. The force determination apparatus measures signal transit time by timing activation and detection and, optionally, determines force components for selected cross-field intersections. The timer which times by activation and detection can be any means for measuring signal transit time. A cross-field intersection is defined by the overlap of a signal generation region and a signal reception region.

  9. Force sensor

    DOEpatents

    Grahn, A.R.

    1993-05-11

    A force sensor and related method for determining force components is described. The force sensor includes a deformable medium having a contact surface against which a force can be applied, a signal generator for generating signals that travel through the deformable medium to the contact surface, a signal receptor for receiving the signal reflected from the contact surface, a generation controller, a reception controller, and a force determination apparatus. The signal generator has one or more signal generation regions for generating the signals. The generation controller selects and activates the signal generation regions. The signal receptor has one or more signal reception regions for receiving signals and for generating detections signals in response thereto. The reception controller selects signal reception regions and detects the detection signals. The force determination apparatus measures signal transit time by timing activation and detection and, optionally, determines force components for selected cross-field intersections. The timer which times by activation and detection can be any means for measuring signal transit time. A cross-field intersection is defined by the overlap of a signal generation region and a signal reception region.

  10. Transient activation of mTOR following forced treadmill exercise in rats.

    PubMed

    Elfving, Betina; Christensen, Tina; Ratner, Cecilia; Wienecke, Jacob; Klein, Anders B

    2013-09-01

    The beneficial effect of exercise on hippocampal plasticity is possibly mediated by increased angiogenesis and neurogenesis. In angiogenesis, insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor (VEGF), and hypoxia-inducible factor 1, alpha subunit (HIF1α) are important factors, while the induction of neurogenesis requires signaling through the VEGF receptor, Flk-1 (VEGFR-2). VEGF expression is believed to be regulated by two distinct mTOR (mammalian target of Rapamycin)-containing multiprotein complexes mTORC1 and mTORC2, respectively. This study was initiated to investigate the effect of exercise on the expression of VEGF, cognate receptors, HIF1α, mTORC1, and mTORC2 in hippocampus and frontal cortex. To this end, we measured messenger RNA (mRNA) levels in rat brain using quantitative real-time polymerase chain reaction (real-time qPCR) after forced treadmill exercise for 1 day, 2 weeks, and 8 weeks. Rats were euthanized either immediately (0 h) or 24 h after last exercise session. Here, we show that exercise affected mRNA levels of VEGF, VEGFR2, and the coreceptor neuropilin 2 (NRP2) when the rats were euthanized immediately, whereas at 24 h only the expression of mTOR was regulated after a single bout of exercise. In conclusion, the effect of treadmill exercise on the VEGF system is acute rather than chronic and there is a transient activation of mTOR. More studies are needed to understand whether this could be beneficial in the treatment of neuropsychiatric disorders. PMID:23536493

  11. 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...

  12. 24 CFR 968.120 - Force account.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 24 Housing and Urban Development 4 2012-04-01 2012-04-01 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...

  13. 24 CFR 968.120 - Force account.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 24 Housing and Urban Development 4 2013-04-01 2013-04-01 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...

  14. 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...

  15. Force response of actively deformed polymer microdroplets: dependence on the solid/liquid boundary condition

    NASA Astrophysics Data System (ADS)

    Heppe, Jonas; McGraw, Joshua D.; Bennewitz, Roland; Jacobs, Karin

    2015-03-01

    In fluid dynamics, the solid/liquid boundary condition can play a major role in the flow behavior of a liquid. For example, in the dewetting of identical polymer films on weak slip or strong slip substrates, large qualitative and quantitative differences are observed. Therefore, when applying an external load to a liquid resting on such substrates, the measured reaction forces and the ensuing flow should also depend on the boundary condition. We present atomic force microscopy measurements in which the reaction force of a cantilever is measured as the tip pierces liquid polymer micron sized droplets and films. These indentations are done on substrates with tuned slip. Accessing the size, depth and rate dependence of the resulting force distance curves, we show an influence of the slip condition on the dissipated energy and adhesion.

  16. Development of Integrated ASR Model Forcing Data and Their Applications to Improve CAM

    SciTech Connect

    Zhang, Minghua

    2016-01-01

    In this project, we have (1) improved the constrained variational analysis algorithm of ARM model forcing data, and (2) used the ARM forcing data to identify systematic biases in clouds and radiation in the CAM5 and design new physical parameterizations to improve it.

  17. Female Labour Force Participation in Developing Countries: A Critique of Current Definitions and Data Collection Methods.

    ERIC Educational Resources Information Center

    Anker, Richard

    1983-01-01

    This article discusses the difficulties involved in obtaining accurate labor force data for Third World women, from the point of view of interviewers, respondents, and labor statisticians or economists. Suggestions are then made regarding alternative definitions of the labor force and survey questionnaire structures in order to overcome some of…

  18. Integrated Training System for Air Force On-the-Job Training: Specification Development. Final Technical Paper.

    ERIC Educational Resources Information Center

    Carson, Stuart B.; And Others.

    The Air Force conducted this study for two purposes: (1) to define the system of Air Force On-the-Job Training (OJT); and (2) to prepare a set of functional specifications for an integrated, base-level OJT evaluation and management system with linkages to the Major Commands and Air Staff. The study was conducted in four phases. During the first…

  19. Influence of stator slots on the development of noise-generating magnetic force waves

    NASA Astrophysics Data System (ADS)

    Wachta, B.

    The calculation of noise in electrical machines is important in the design of these machines. It is shown that the magnetic anisotropy of a laminated stator core caused by stator slots has a substantial effect on the force waves acting on the yoke. The force waves are described simply using a modulation function and the Fourier coefficients of the waves. The effects of the amplitude of the magnetic force waves are discussed, and the effectiveness of stator slot skewing is determined. It is shown that subharmonics can be generated by the slotting (affecting the harmonic number of the force waves), and that for specific harmonic numbers, a reversal in the direction of rotation of force waves takes place. The effectiveness of the method is substantiated by a practical example.

  20. 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

  1. 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

  2. Stress and Androgen Activity During Fetal Development.

    PubMed

    Barrett, Emily S; Swan, Shanna H

    2015-10-01

    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

  3. Detection and characterization of transient forcing episodes affecting earthquake activity in the Aleutian Arc system

    NASA Astrophysics Data System (ADS)

    Reverso, T.; Marsan, D.; Helmstetter, A.

    2015-02-01

    Crustal, slow deformation transients can be caused by fluid or magmatic intrusions, and by slow slip on faults. They can affect earthquake dynamics, if they occur close to or within seismically active zones. We here further develop, and test, a statistical method for detecting and characterizing seismicity anomalies that is only based on earthquake occurrence times and locations. We make use of this method to analyze the 2004-2013 seismicity at mc = 3.5 in the Aleutian subduction system, to find six statistically significant anomalies, with typical 1 day duration and 30 to 50 km size, that are likely related to slow deformation transients. They tend to be located in zones characterized by intermediate seismic coupling, and to mark the termination of past large to mega-thrust earthquakes. These anomalies account for a non-negligible (9%) part of the total activity, proving that non-stationary aseismic loading plays an important role in the dynamics of crustal deformation.

  4. Chemical Potentials, Activity Coefficients, and Solubility in Aqueous NaCl Solutions: Prediction by Polarizable Force Fields.

    PubMed

    Moučka, Filip; Nezbeda, Ivo; Smith, William R

    2015-04-14

    We describe a computationally efficient molecular simulation methodology for calculating the concentration dependence of the chemical potentials of both solute and solvent in aqueous electrolyte solutions, based on simulations of the salt chemical potential alone. We use our approach to study the predictions for aqueous NaCl solutions at ambient conditions of these properties by the recently developed polarizable force fields (FFs) AH/BK3 of Kiss and Baranyai (J. Chem. Phys. 2013, 138, 204507) and AH/SWM4-DP of Lamoureux and Roux (J. Phys. Chem. B 2006, 110, 3308 - 3322) and by the nonpolarizable JC FF of Joung and Cheatham tailored to SPC/E water (J. Phys. Chem. B 2008, 112, 9020 - 9041). We also consider their predictions of the concentration dependence of the electrolyte activity coefficient, the crystalline solid chemical potential, the electrolyte solubility, and the solution specific volume. We first highlight the disagreement in the literature concerning calculations of solubility by means of molecular simulation in the case of the JC FF and provide strong evidence of the correctness of our methodology based on recent independently obtained results for this important test case. We then compare the predictions of the three FFs with each other and with experiment and draw conclusions concerning their relative merits, with particular emphasis on the salt chemical potential and activity coefficient vs concentration curves and their derivatives. The latter curves have only previously been available from Kirkwood-Buff integrals, which require approximate numerical integrations over system pair correlation functions at each concentration. Unlike the case of the other FFs, the AH/BK3 curves are nearly parallel to the corresponding experimental curves at moderate and higher concentrations. This leads to an excellent prediction of the water chemical potential via the Gibbs-Duhem equation and enables the activity coefficient curve to be brought into excellent agreement

  5. Integrated Analysis of Contractile Kinetics, Force Generation, and Electrical Activity in Single Human Stem Cell-Derived Cardiomyocytes.

    PubMed

    Kijlstra, Jan David; Hu, Dongjian; Mittal, Nikhil; Kausel, Eduardo; van der Meer, Peter; Garakani, Arman; Domian, Ibrahim J

    2015-12-01

    The quantitative analysis of cardiomyocyte function is essential for stem cell-based approaches for the in vitro study of human cardiac physiology and pathophysiology. We present a method to comprehensively assess the function of single human pluripotent stem cell-derived cardiomyocyte (hPSC-CMs) through simultaneous quantitative analysis of contraction kinetics, force generation, and electrical activity. We demonstrate that statistical analysis of movies of contracting hPSC-CMs can be used to quantify changes in cellular morphology over time and compute contractile kinetics. Using a biomechanical model that incorporates substrate stiffness, we calculate cardiomyocyte force generation at single-cell resolution and validate this approach with conventional traction force microscopy. The addition of fluorescent calcium indicators or membrane potential dyes allows the simultaneous analysis of contractility and calcium handling or action potential morphology. Accordingly, our approach has the potential for broad application in the study of cardiac disease, drug discovery, and cardiotoxicity screening. PMID:26626178

  6. Integrated Analysis of Contractile Kinetics, Force Generation, and Electrical Activity in Single Human Stem Cell-Derived Cardiomyocytes

    PubMed Central

    Kijlstra, Jan David; Hu, Dongjian; Mittal, Nikhil; Kausel, Eduardo; van der Meer, Peter; Garakani, Arman; Domian, Ibrahim J.

    2015-01-01

    Summary The quantitative analysis of cardiomyocyte function is essential for stem cell-based approaches for the in vitro study of human cardiac physiology and pathophysiology. We present a method to comprehensively assess the function of single human pluripotent stem cell-derived cardiomyocyte (hPSC-CMs) through simultaneous quantitative analysis of contraction kinetics, force generation, and electrical activity. We demonstrate that statistical analysis of movies of contracting hPSC-CMs can be used to quantify changes in cellular morphology over time and compute contractile kinetics. Using a biomechanical model that incorporates substrate stiffness, we calculate cardiomyocyte force generation at single-cell resolution and validate this approach with conventional traction force microscopy. The addition of fluorescent calcium indicators or membrane potential dyes allows the simultaneous analysis of contractility and calcium handling or action potential morphology. Accordingly, our approach has the potential for broad application in the study of cardiac disease, drug discovery, and cardiotoxicity screening. PMID:26626178

  7. Upregulation of Forces and Morphogenic Asymmetries in Dorsal Closure during Drosophila Development

    PubMed Central

    Peralta, X. G.; Toyama, Y.; Hutson, M. S.; Montague, R.; Venakides, S.; Kiehart, D. P.; Edwards, G. S.

    2007-01-01

    Tissue dynamics during dorsal closure, a stage of Drosophila development, provide a model system for cell sheet morphogenesis and wound healing. Dorsal closure is characterized by complex cell sheet movements, driven by multiple tissue specific forces, which are coordinated in space, synchronized in time, and resilient to UV-laser perturbations. The mechanisms responsible for these attributes are not fully understood. We measured spatial, kinematic, and dynamic antero-posterior asymmetries to biophysically characterize both resiliency to laser perturbations and failure of closure in mutant embryos and compared them to natural asymmetries in unperturbed, wild-type closure. We quantified and mathematically modeled two processes that are upregulated to provide resiliency—contractility of the amnioserosa and formation of a seam between advancing epidermal sheets, i.e., zipping. Both processes are spatially removed from the laser-targeted site, indicating they are not a local response to laser-induced wounding and suggesting mechanosensitive and/or chemosensitive mechanisms for upregulation. In mutant embryos, tissue junctions initially fail at the anterior end indicating inhomogeneous mechanical stresses attributable to head involution, another developmental process that occurs concomitant with the end stages of closure. Asymmetries in these mutants are reversed compared to wild-type, and inhomogeneous stresses may cause asymmetries in wild-type closure. PMID:17218455

  8. Climate forcing of unprecedented intense-hurricane activity in the last 2000 years

    NASA Astrophysics Data System (ADS)

    Donnelly, Jeffrey P.; Hawkes, Andrea D.; Lane, Philip; MacDonald, Dana; Shuman, Bryan N.; Toomey, Michael R.; van Hengstum, Peter J.; Woodruff, Jonathan D.

    2015-02-01

    How climate controls hurricane variability has critical implications for society is not well understood. In part, our understanding is hampered by the short and incomplete observational hurricane record. Here we present a synthesis of intense-hurricane activity from the western North Atlantic over the past two millennia, which is supported by a new, exceptionally well-resolved record from Salt Pond, Massachusetts (USA). At Salt Pond, three coarse grained event beds deposited in the historical interval are consistent with severe hurricanes in 1991 (Bob), 1675, and 1635 C.E., and provide modern analogs for 32 other prehistoric event beds. Two intervals of heightened frequency of event bed deposition between 1400 and 1675 C.E. (10 events) and 150 and 1150 C.E. (23 events), represent the local expression of coherent regional patterns in intense-hurricane-induced event beds. Our synthesis indicates that much of the western North Atlantic appears to have been active between 250 and 1150 C.E., with high levels of activity persisting in the Caribbean and Gulf of Mexico until 1400 C.E. This interval was one with relatively warm sea surface temperatures (SSTs) in the main development region (MDR). A shift in activity to the North American east coast occurred ca. 1400 C.E., with more frequent severe hurricane strikes recorded from The Bahamas to New England between 1400 and 1675 C.E. A warm SST anomaly along the western North Atlantic, rather than within the MDR, likely contributed to the later active interval being restricted to the east coast.

  9. Simulation Based Low-Cost Composite Process Development at the US Air Force Research Laboratory

    NASA Technical Reports Server (NTRS)

    Rice, Brian P.; Lee, C. William; Curliss, David B.

    2003-01-01

    Low-cost composite research in the US Air Force Research Laboratory, Materials and Manufacturing Directorate, Organic Matrix Composites Branch has focused on the theme of affordable performance. Practically, this means that we use a very broad view when considering the affordability of composites. Factors such as material costs, labor costs, recurring and nonrecurring manufacturing costs are balanced against performance to arrive at the relative affordability vs. performance measure of merit. The research efforts discussed here are two projects focused on affordable processing of composites. The first topic is the use of a neural network scheme to model cure reaction kinetics, then utilize the kinetics coupled with simple heat transport models to predict, in real-time, future exotherms and control them. The neural network scheme is demonstrated to be very robust and a much more efficient method that mechanistic cure modeling approach. This enables very practical low-cost processing of thick composite parts. The second project is liquid composite molding (LCM) process simulation. LCM processing of large 3D integrated composite parts has been demonstrated to be a very cost effective way to produce large integrated aerospace components specific examples of LCM processes are resin transfer molding (RTM), vacuum assisted resin transfer molding (VARTM), and other similar approaches. LCM process simulation is a critical part of developing an LCM process approach. Flow simulation enables the development of the most robust approach to introducing resin into complex preforms. Furthermore, LCM simulation can be used in conjunction with flow front sensors to control the LCM process in real-time to account for preform or resin variability.

  10. 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

    ... has received a request from the U.S. Air Force (USAF) for authorization to take marine mammals... (MMPA), NMFS is announcing our receipt of the USAF's request for the development and implementation of... comments on the USAF's application and request. DATES: Comments and information must be received no...

  11. 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.

  12. Development and preliminary testing of an instrumented object for force analysis during grasping.

    PubMed

    Romeo, R A; Cordella, F; Zollo, L; Formica, D; Saccomandi, P; Schena, E; Carpino, G; Davalli, A; Sacchetti, R; Guglielmelli, E

    2015-08-01

    This paper presents the design and realization of an instrumented object for force analysis during grasping. The object, with spherical shape, has been constructed with three contact areas in order to allow performing a tripod grasp. Force Sensing Resistor (FSR) sensors have been employed for normal force measurements, while an accelerometer has been used for slip detection. An electronic board for data acquisition has been embedded into the object, so that only the cables for power supply exit from it. Validation tests have been carried out for: (i) comparing the force measurements with a ground truth; (ii) assessing the capability of the accelerometer to detect slippage for different roughness values; (iii) evaluating object performance in grasp trials performed by a human subject. PMID:26737835

  13. Spatial organization acts on cell signaling: how physical force contributes to the development of cancer

    PubMed Central

    2010-01-01

    Cells constantly encounter physical forces and respond to neighbors and circulating factors by triggering intracellular signaling cascades that in turn affect their behavior. The mechanisms by which cells transduce mechanical signals to downstream biochemical changes are not well understood. In their work, Salaita and coworkers show that the spatial organization of cell surface receptors is crucial for mechanotransduction. Consequently, force modulation that disrupts the mechanochemical coupling may represent a critical step in cancerogenesis. PMID:20804566

  14. Joint positioning sense, perceived force level and two-point discrimination tests of young and active elderly adults

    PubMed Central

    Franco, Priscila G.; Santos, Karini B.; Rodacki, André L. F.

    2015-01-01

    Background: Changes in the proprioceptive system are associated with aging. Proprioception is important to maintaining and/or recovering balance and to reducing the risk of falls. Objective: To compare the performance of young and active elderly adults in three proprioceptive tests. Method: Twenty-one active elderly participants (66.9±5.5 years) and 21 healthy young participants (24.6±3.9 years) were evaluated in the following tests: perception of position of the ankle and hip joints, perceived force level of the ankle joint, and two-point discrimination of the sole of the foot. Results: No differences (p>0.05) were found between groups for the joint position and perceived force level. On the other hand, the elderly participants showed lower sensitivity in the two-point discrimination (higher threshold) when compared to the young participants (p < 0.01). Conclusion: Except for the cutaneous plantar sensitivity, the active elderly participants had maintained proprioception. Their physical activity status may explain similarities between groups for the joint position sense and perceived force level, however it may not be sufficient to prevent sensory degeneration with aging. PMID:26443978

  15. RUNX2 and the PI3K/AKT axis reciprocal activation as a driving force for tumor progression.

    PubMed

    Cohen-Solal, Karine A; Boregowda, Rajeev K; Lasfar, Ahmed

    2015-01-01

    From the first reported role of the transcription factor RUNX2 in osteoblast and chondrocyte differentiation and migration to its involvement in promigratory/proinvasive behavior of breast, prostate, and thyroid cancer cells, osteosarcoma, or melanoma cells, RUNX2 currently emerges as a key player in metastasis. In this review, we address the interaction of RUNX2 with the PI3K/AKT signaling pathway, one of the critical axes controlling cancer growth and metastasis. AKT, either by directly phosphorylating/activating RUNX2 or phosphorylating/inactivating regulators of RUNX2 stability or activity, contributes to RUNX2 transcriptional activity. Reciprocally, the activation of the PI3K/AKT pathway by RUNX2 regulation of its different components has been described in non-transformed and transformed cells. This mutual activation in the context of cancer cells exhibiting constitutive AKT activation and high levels of RUNX2 might constitute a major driving force in tumor progression and aggressiveness. PMID:26204939

  16. The cyclotron development activities at CIAE

    NASA Astrophysics Data System (ADS)

    Zhang, Tianjue; Li, Zhenguo; An, Shizhong; Yin, Zhiguo; Yang, Jianjun; Yang, Fang

    2011-12-01

    The cyclotron has an obvious advantage in offering high average current and beam power. Cyclotron development for various applications, e.g. radioactive ion-beam (RIB) generation, clean nuclear energy systems, medical diagnostics and isotope production, were performed at China Institute of Atomic Energy (CIAE) for over 50 years. At the moment two cyclotrons are being built at CIAE, the 100 MeV, CYCIAE-100, and a 14 MeV, the CYCIAE-14. Meanwhile, we are designing and proposing to build a number of cyclotrons with different energies, among them are the CYCIAE-70, the CYCIAE-800, and the upgrading of CYCIAE-CRM, which is going to increase its beam current to mA level. The contribution will present an overall introduction to the cyclotron development activities conducted at CIAE, with different emphasis to each project in order to demonstrate the design and construction highlights.

  17. Air Force space power technology development at the Phillips research site

    SciTech Connect

    Reinhardt, K.; Radzykewycz, D.; James, W.R.; Donet, C.; Mayberry, C.

    1998-07-01

    Technology development in the areas of high efficiency, light-weight, compact, reliable and cost-effective space power components are needed to support the development of next-generation military and commercial satellites. In order to meet the demand for increased satellite payload mass and power, and reduce launch vehicle size and cost, an increasing amount of attention is being given to the satellite electric power system (EPS) performance in terms of specific power (W/kg), size, stowed volume, and cost. The EPS is responsible for providing uninterrupted, fault-tolerant electrical power to satellite payload and housekeeping equipment throughout the lifetime of the mission. Today's smallsats and conventional largesats vary in power level and mass from about 1000 watts and 225 kg or less, up to as much as 15 kW and >5,000 kg, respectively. In the case of smallsats, recent trends in shrinking space budgets have pushed mission planners towards the use of cheaper smallsat designs capable of launch on smaller, cheaper, and more easily deployed vehicles. The US intelligence community recently evaluated requirements for future surveillance missions and acknowledged the advantages of lower cost smallsats to address tomorrow's warfighter needs, which include increased flexibility, improved performance, and the ability to launch them easily when needed. In contrast to smallsat applications, mission planners have also acknowledged the need for significantly larger 30-100 kW monstersats to enable next-generation communications, radar, and weapons platform functions. In order to meet projected smallsat and monstersat design requirements, revolutionary advancements in EPS component technology are required over today's conventional technologies. The goal is to increase total EPS specific power through advancements in component technology to reduce EPS mass from 20-30% of total satellite mass to approximately 10%. A complement of on-going EPS technology development programs at

  18. Reactive force field development for magnesium chloride hydrates and its application for seasonal heat storage.

    PubMed

    Pathak, Amar Deep; Nedea, Silvia; van Duin, Adri C T; Zondag, Herbert; Rindt, Camilo; Smeulders, David

    2016-06-21

    MgCl2 hydrates are considered as high-potential candidates for seasonal heat storage materials. These materials have high storage capacity and fast dehydration kinetics. However, as a side reaction to dehydration, hydrolysis may occur. Hydrolysis is an irreversible reaction, which produces HCl gas thus affecting the durability of heat storage systems. In this study, we present the parameterization of a reactive force field (ReaxFF) for MgCl2 hydrates to study the dehydration and hydrolysis kinetics of MgCl2·H2O and MgCl2·2H2O. The ReaxFF parameters have been derived by training against quantum mechanics data obtained from Density Functional Theory (DFT) calculations consisting of bond dissociation curves, angle bending curves, reaction enthalpies, and equation of state. A single-parameter search algorithm in combination with a Metropolis Monte Carlo algorithm is successfully used for this ReaxFF parameterization. The newly developed force field is validated by examining the elastic properties of MgCl2 hydrates and the proton transfer reaction barrier, which is important for the hydrolysis reaction. The bulk moduli of MgCl2·H2O and MgCl2·2H2O obtained from ReaxFF are in close agreement with the bulk moduli obtained from DFT. A barrier of 20.24 kcal mol(-1) for the proton transfer in MgCl2·2H2O is obtained, which is in good agreement with the barrier (19.55 kcal mol(-1)) obtained from DFT. Molecular dynamics simulations using the newly developed ReaxFF on 2D-periodic slabs of MgCl2·H2O and MgCl2·2H2O show that the dehydration rate increases more rapidly with temperature in MgCl2·H2O than in MgCl2·2H2O, in the temperature range 300-500 K. The onset temperature of HCl formation, a crucial design parameter in seasonal heat storage systems, is observed at 340 K for MgCl2·H2O, which is in agreement with experiments. The HCl formation is not observed for MgCl2·2H2O. The diffusion coefficient of H2O through MgCl2·H2O is lower than through MgCl2·2H2O, and can

  19. In Flight Evaluation of Active Inceptor Force-Feel Characteristics and Handling Qualities

    NASA Technical Reports Server (NTRS)

    Lusardi, Jeff A.; Blanken, Chris L.; Ott, Carl Raymond; Malpica, Carlos A.; von Gruenhagen, Wolfgang

    2012-01-01

    The effect of inceptor feel-system characteristics on piloted handling qualities has been a research topic of interest for many years. Most of the research efforts have focused on advanced fly-by-wire fixed-wing aircraft with only a few studies investigating the effects on rotorcraft. Consequently, only limited guidance is available on how cyclic force-feel characteristics should be set to obtain optimal handling qualities for rotorcraft. To study this effect, the U.S. Army Aeroflightdynamics Directorate working with the DLR Institute of Flight Systems in Germany under Task X of the U.S. German Memorandum of Understanding have been conducting flight test evaluations. In the U.S., five experimental test pilots have completed evaluations of two Mission Task Elements (MTEs) from ADS-33E-PRF and two command/response types for a matrix of center-stick cyclic force-feel characteristics at Moffett Field. In Germany, three experimental test Pilots have conducted initial evaluations of the two MTEs with two command/response types for a parallel matrix of side-stick cyclic force-feel characteristics at WTD-61 in Manching. The resulting data set is used to correlate the effect of changes in natural frequency and damping ratio of the cyclic inceptor on the piloted handling qualities. Existing criteria in ADS-33E and a proposed Handling Qualities Sensitivity Function that includes the effects of the cyclic force-feel characteristics are also evaluated against the data set and discussed.

  20. Materials on Technical Resources and Program Evaluation. Teacher Corps Task Forces Document II. Developmental Training Activities.

    ERIC Educational Resources Information Center

    Nebraska Univ., Omaha. Center for Urban Education.

    This report by a National Task Force of the Teacher Corps provides charts, tables, and analysis of two distinct facets of previous analysis of the work of the Teacher Corps. The first is a detailed consideration of the availability and use of technical resources. Included are considerations of the purposes for providing technical resources;…

  1. 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

  2. Development of a mathematical model for predicting electrically elicited quadriceps femoris muscle forces during isovelocity knee joint motion

    PubMed Central

    Perumal, Ramu; Wexler, Anthony S; Binder-Macleod, Stuart A

    2008-01-01

    Background Direct electrical activation of skeletal muscles of patients with upper motor neuron lesions can restore functional movements, such as standing or walking. Because responses to electrical stimulation are highly nonlinear and time varying, accurate control of muscles to produce functional movements is very difficult. Accurate and predictive mathematical models can facilitate the design of stimulation patterns and control strategies that will produce the desired force and motion. In the present study, we build upon our previous isometric model to capture the effects of constant angular velocity on the forces produced during electrically elicited concentric contractions of healthy human quadriceps femoris muscle. Modelling the isovelocity condition is important because it will enable us to understand how our model behaves under the relatively simple condition of constant velocity and will enable us to better understand the interactions of muscle length, limb velocity, and stimulation pattern on the force produced by the muscle. Methods An additional term was introduced into our previous isometric model to predict the force responses during constant velocity limb motion. Ten healthy subjects were recruited for the study. Using a KinCom dynamometer, isometric and isovelocity force data were collected from the human quadriceps femoris muscle in response to a wide range of stimulation frequencies and patterns. % error, linear regression trend lines, and paired t-tests were used to test how well the model predicted the experimental forces. In addition, sensitivity analysis was performed using Fourier Amplitude Sensitivity Test to obtain a measure of the sensitivity of our model's output to changes in model parameters. Results Percentage RMS errors between modelled and experimental forces determined for each subject at each stimulation pattern and velocity showed that the errors were in general less than 20%. The coefficients of determination between the measured

  3. Associated decrements in rate of force development and neural drive after maximal eccentric exercise.

    PubMed

    Farup, J; Rahbek, S K; Bjerre, J; de Paoli, F; Vissing, K

    2016-05-01

    The present study investigated the changes in contractile rate of force development (RFD) and the neural drive following a single bout of eccentric exercise. Twenty-four subjects performed 15 × 10 maximal isokinetic eccentric knee extensor contractions. Prior to and at 24, 48, 72, 96, and 168 h during post-exercise recovery, isometric RFD (30, 50 100, and 200 ms), normalized RFD [1/6,1/2, and 2/3 of maximal voluntary contraction (MVC)] and rate of electromyography rise (RER; 30, 50, and 75 ms) were measured. RFD decreased by 28-42% peaking at 48 h (P < 0.01-P < 0.001) and remained depressed at 168 h (P < 0.05). Normalized RFD at 2/3 of MVC decreased by 22-39% (P < 0.01), peaked at 72 h and returned to baseline at 168 h. These changes in RFD were associated with a decrease in RER at 48 h-96 h (P < 0.05-P < 0.001). Accumulated changes (area under curve) revealed a greater relative decrease in accumulated RFD at 100 ms by -2727 ± 309 (%h; P < 0.05) and 200 ms by -3035 ± 271 (%h; P < 0.001) compared with MVC, which decreased, by -1956 ± 234 (%h). In conclusion, RFD and RER are both markedly reduced following a bout of maximal eccentric exercise. This association suggests that exercise-induced decrements in RFD can, in part, be explained decrements in neural drive. PMID:25944178

  4. Theoretical Model of Drag Force Impact on a Model International Space Station (ISS) Satellite due to Solar Activity

    NASA Astrophysics Data System (ADS)

    Nwankwo, Victor U. J.; Chakrabarti, Sandip Kumar

    The International Space Station (ISS) is the single largest and most complex scientific and engineering space structure in human history. Its orbital parameters make it extremely vulnerable to severe atmospheric drag force. Complex interactions between solar energetic particles, ultraviolet (UV) radiation with atmosphere and geomagnetic field cause heating and subsequent expansion of the upper atmosphere. This condition increases drag on low Earth orbit satellites (LEOSs) and varies with current space weather conditions. In this work, we apply the NRLMSISE-00 empirical atmospheric density model, as a function of space environmental parameters, to model drag force impact on a model LEOS during variation of solar activity. Applying the resulting drag model on a model ISS satellite we observe that depending on the severity and/or stage of solar activity or cycle, a massive artificial satellite could experience orbit decay rate of up to 2.95km/month during solar maximum and up to 1km/month during solar minimum.

  5. Activation of caspase-3 and its correlation with shear force in bovine skeletal muscles during postmortem conditioning.

    PubMed

    Cao, J-X; Ou, C-R; Zou, Y-F; Ye, K-P; Zhang, Q-Q; Khan, M A; Pan, D-D; Zhou, G

    2013-09-01

    The study was aimed at exploring the mechanism of tenderization by establishing a correlation between caspase-3 activity and shear force, verifying the activation occurring by analyzing active caspase-3 and cleaved poly (ADP-ribose) polymerase (PARP) fragments, and understanding the pathways involved in activation of caspase-3 by evaluating its correlation with caspase-8 and -9 activities in LM, semitendinosus (STN), and psoas minor (PM) muscles. The results indicated that shear force decreased at 48 h in PM (P < 0.01), LM (P < 0.01), and STN (P < 0.05). We detected p22, p23, p20, and p18 caspase fragments as well as distinctive PARP fragments of 24 kDa by caspase-3 and 36 kDa by µ-calpain. Caspase-3 activity correlated with shear force negatively at 24 and 48 h in STN (P < 0.01 at 24 h; P < 0.01 at 48 h), PM (P < 0.001 at 24 h; P < 0.01 at 48 h), and LM muscles (P < 0.05 at 24 h; P < 0.01 at 48 h). The greatest activities of caspase-8 (P < 0.001 in PM and STN; P < 0.01 in LM) and caspase-9 (P < 0.001 in muscles) appeared at 4 h whereas that of caspase-3 was at 24 h (P < 0.001 in muscles). Caspase-9 activity correlated positively with caspase-3 at 4, 24, and 48 h in STN (P < 0.01 at 4 h; P < 0.05 at 24 h; P < 0.001 at 48 h) and at 4 and 96 h in PM (P < 0.001 at 4 h; P < 0.05 at 96 h) and LM muscles (P < 0.001 at 4 h; P < 0.001 at 96 h). The caspase-8 activity correlated with caspase-3 at 4, 48, and 96 h in STN (P < 0.05 at 4 h; P < 0.001 at 48 h; P < 0.05 at 96 h), at 4 and 24 h in PM (P < 0.001 at 4 h; P < 0.05 at 24 h), and at 4 and 96 h in LM (P < 0.001 at 4 h; P < 0.01 at 96 h). We concluded that caspase-3 was associated with the decline of shear force; the activation of caspase-3 was mediated by caspases -8 and -9 in muscles. However, more detailed studies are needed to define the precise mechanism for the cleavage of pro-caspases -8 and -9 during conditioning. PMID:23893998

  6. Force-specific activation of Smad1/5 regulates vascular endothelial cell cycle progression in response to disturbed flow.

    PubMed

    Zhou, Jing; Lee, Pei-Ling; Tsai, Chien-Sung; Lee, Chih-I; Yang, Tung-Lin; Chuang, Han-Sheng; Lin, Wei-Wen; Lin, Ting-Er; Lim, Seh Hong; Wei, Shu-Yi; Chen, Yuh-Lien; Chien, Shu; Chiu, Jeng-Jiann

    2012-05-15

    Vascular endothelial cells (ECs) are constantly exposed to blood flow-induced shear stress, but the mechanism of force-specific activation of their signaling to modulate cellular function remains unclear. We have demonstrated that bone morphogenetic protein receptor (BMPR)-specific Smad1/5 can be force-specifically activated by oscillatory shear stress (OSS) in ECs to cause cell cycle progression. Smad1/5 is highly activated in ECs of atherosclerotic lesions in diseased human coronary arteries from patients with end-stage heart failure undergoing heart transplantation and from apolipoprotein E-deficient mice. Application of OSS (0.5 ± 4 dyn/cm(2)) causes the sustained activation of Smad1/5 in ECs through activations of mammalian target of rapamycin and p70S6 kinase, leading to up-regulation of cyclin A and down-regulations of p21(CIP1) and p27(KIP1) and, hence, EC cycle progression. En face examination of rat aortas reveals high levels of phospho-Smad1/5 in ECs of the inner, but not the outer, curvature of aortic arch, nor the straight segment of thoracic aorta [corrected]. Immunohistochemical and en face examinations of the experimentally stenosed abdominal aorta in rats show high levels of phospho-Smad1/5 in ECs at poststenotic sites, where OSS occurs. These OSS activations of EC Smad1/5 in vitro and in vivo are not inhibited by the BMP-specific antagonist Noggin and, hence, are independent of BMP ligand. Transfecting ECs with Smad1/5-specific small interfering RNAs inhibits the OSS-induced EC cycle progression. Our findings demonstrate the force-specificity of the activation of Smad1/5 and its contribution to cell cycle progression in ECs induced by disturbed flow. PMID:22550179

  7. Mountains of Work: NACUBO TRA97 Task Force Takes Proactive Stance in Developing Processes, Recommending Changes, and Offering Advice.

    ERIC Educational Resources Information Center

    Gross, Anne C.; Bachinger, Mary M.; Whalen, Edward L.

    1998-01-01

    A National Association of College and University Business Officers (NACUBO) task force has developed a process guide, list of policy issues and unsolved questions, and recommendations for colleges and universities to use in complying with the reporting requirements of the Tax Relief Act of 1997, which provides parents of college students with tax…

  8. Leadership Development and Training in the British Armed Forces: Challenging the Assumptions to Meet the Demands of a New Era

    ERIC Educational Resources Information Center

    Alexandrou, Alex; Davies, John Dwyfor

    2004-01-01

    It is fair to state that, until relatively recently, the British Armed Forces believed that they led the way in leadership development and training, and with some justification. However, the present New Labour administration and the Ministry of Defence "MoD" do not share that view, and have issued a direct challenge to the Armed Services to…

  9. Successive smoothing algorithm for constructing the semiempirical model developed at ONERA to predict unsteady aerodynamic forces. [aeroelasticity in helicopters

    NASA Technical Reports Server (NTRS)

    Petot, D.; Loiseau, H.

    1982-01-01

    Unsteady aerodynamic methods adopted for the study of aeroelasticity in helicopters are considered with focus on the development of a semiempirical model of unsteady aerodynamic forces acting on an oscillating profile at high incidence. The successive smoothing algorithm described leads to the model's coefficients in a very satisfactory manner.

  10. Use of a Mobile Application to Help Students Develop Skills Needed in Solving Force Equilibrium Problems

    NASA Astrophysics Data System (ADS)

    Yang, Eunice

    2016-02-01

    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 diagrams (FBDs) and provides solutions in real time. It is a cost-free software that is available for download on the Internet. The software is supported on the iOS™, Android™, and Google Chrome™ platforms. It is easy to use and the learning curve is approximately two hours using the tutorial provided within the app. The use of ForceEffect has the ability to provide students different problem modalities (textbook, real-world, and design) to help them acquire and improve on skills that are needed to solve force equilibrium problems. Although this paper focuses on the engineering mechanics statics course, the technology discussed is also relevant to the introductory physics course.

  11. OOTW Force Design Tools

    SciTech Connect

    Bell, R.E.; Hartley, D.S.III; Packard, S.L.

    1999-05-01

    This report documents refined requirements for tools to aid the process of force design in Operations Other Than War (OOTWs). It recommends actions for the creation of one tool and work on other tools relating to mission planning. It also identifies the governmental agencies and commands with interests in each tool, from whom should come the user advisory groups overseeing the respective tool development activities. The understanding of OOTWs and their analytical support requirements has matured to the point where action can be taken in three areas: force design, collaborative analysis, and impact analysis. While the nature of the action and the length of time before complete results can be expected depends on the area, in each case the action should begin immediately. Force design for OOTWs is not a technically difficult process. Like force design for combat operations, it is a process of matching the capabilities of forces against the specified and implied tasks of the operation, considering the constraints of logistics, transport and force availabilities. However, there is a critical difference that restricts the usefulness of combat force design tools for OOTWs: the combat tools are built to infer non-combat capability requirements from combat capability requirements and cannot reverse the direction of the inference, as is required for OOTWs. Recently, OOTWs have played a larger role in force assessment, system effectiveness and tradeoff analysis, and concept and doctrine development and analysis. In the first Quadrennial Defense Review (QDR), each of the Services created its own OOTW force design tool. Unfortunately, the tools address different parts of the problem and do not coordinate the use of competing capabilities. These tools satisfied the immediate requirements of the QDR, but do not provide a long-term cost-effective solution.

  12. Development of Lorentz force-type self-bearing motor for an alternative axial flow blood pump design.

    PubMed

    Lim, Tau Meng; Zhang, Dongsheng

    2006-05-01

    A Lorentz force-type self-bearing motor was developed to provide delivery of both motoring torque and levitation force for an alternative axial flow blood pump design with an enclosed impeller. The axial flow pumps currently available introduce electromagnetic coupling from the motor's stator to the impeller by means of permanent magnets (PMs) embedded in the tips of the pump's blades. This design has distinct disadvantages, for example, pumping efficiency and electromagnetic coupling transmission are compromised by the constrained or poor geometry of the blades and limited pole width of the PMs, respectively. In this research, a Lorentz force-type self-bearing motor was developed. It is composed of (i) an eight-pole PM hollow-cylindrical rotor assembly supposedly to house and enclose the impeller of an axial flow blood pump, and (ii) a six-pole stator with two sets of copper wire and different winding configurations to provide the motoring torque and levitating force for the rotor assembly. MATLAB's xPC Target interface hardware was used as the rapid prototyping tool for the development of the controller for the self-bearing motor. Experimental results on a free/simply supported rotor assembly validated the design feasibility and control algorithm effectiveness in providing both the motoring torque and levitation force for the rotor. When levitated, a maximum orbital displacement of 0.3 mm corresponding to 1050 rpm of the rotor was measured by two eddy current probes placed in the orthogonal direction. This design has the advantage of eliminating the trade-off between motoring torques, levitating force, and pumping efficiency of previous studies. It also indicated the benefits of enclosed-impeller design as having good dynamic response, linearity, and better reliability. The nonmechanical contact feature between rotating and stationary parts will further reduce hemolysis and thromboembolitic tendencies in a typical blood pump application. PMID:16683951

  13. 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...

  14. 24 CFR 1003.203 - Special economic development activities.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 24 Housing and Urban Development 4 2013-04-01 2013-04-01 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...

  15. 24 CFR 1003.203 - Special economic development activities.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 24 Housing and Urban Development 4 2012-04-01 2012-04-01 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...

  16. 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...

  17. Implant Site Development for Enhancing Esthetics of Soft and Hard Tissue and Simplification of Implant Surgery Using a Forced Eruption.

    PubMed

    Joo, Ji-Young; Son, Sieun; Lee, Ju-Youn

    2016-01-01

    The keys to successful esthetic implant therapy in the anterior region are natural-looking implant restorations and an adequate alveolar ridge volume. Destruction of periodontal tissue resulting from periodontal and/or endodontic inflammation causes esthetic problems. Forced eruption is a valuable adjunct to augmenting the soft and hard tissue where the alveolar ridge is insufficient for esthetics. In this article, forced eruption was adopted for implant site development prior to implant placement and the periodontal tissue was augmented vertically using this technique. This technique simplified the surgical implant procedure without a need for advanced augmentation. PMID:27333017

  18. Novel magnetic tips developed for the switching magnetization magnetic force microscopy.

    SciTech Connect

    Cambel, V.; Elias, P.; Gregusova, D.; Fedor, J.; Martaus, J.; Karapetrov, G.; Novosad, V.; Kostic, I.; Materials Science Division; Slovak Academy of Sciences

    2010-07-01

    Using micromagnetic calculations we search for optimal magnetic properties of novel magnetic tips to be used for a Switching Magnetization Magnetic Force Microscopy (SM-MFM), a novel technique based on two-pass scanning with reversed tip magnetization. Within the technique the sum of two scans images local atomic forces and their difference maps the local magnetic forces. The tip magnetization is switched during the scanning by a small magnetic field. The technology of novel low-coercitive magnetic tips is proposed. For best performance the tips must exhibit low magnetic moment, low switching field, and single-domain state at remanence. Such tips are equipped with Permalloy objects of a precise shape that are defined on their tilted sides. We calculate switching fields of such tips by solving the micromagnetic problem to find the optimum shape and dimensions of the Permalloy objects located on the tips. Among them, hexagon was found as the best shape for the tips.

  19. Volcanic spreading forcing and feedback in geothermal reservoir development, Amiata Volcano, Italia

    NASA Astrophysics Data System (ADS)

    Borgia, Andrea; Mazzoldi, Alberto; Brunori, Carlo Alberto; Allocca, Carmine; Delcroix, Carlo; Micheli, Luigi; Vercellino, Alberto; Grieco, Giovanni

    2014-09-01

    We made a stratigraphic, structural and morphologic study of the Amiata Volcano in Italy. We find that the edifice is dissected by intersecting grabens that accommodate the collapse of the higher sectors of the volcano. In turn, a number of compressive structures and diapirs exist around the margin of the volcano. These structures create an angular drainage pattern, with stream damming and captures, and a set of lakes within and around the volcano. We interpret these structures as the result of volcanic spreading of Amiata on its weak substratum, formed by the late Triassic evaporites (Burano Anhydrites) and the Middle-Jurassic to Early-Cretaceous clayey chaotic complexes (Ligurian Complex). Regional doming created a slope in the basement facilitating the outward flow and spreading of the ductile layers forced by the volcanic load. We model the dynamics of spreading with a scaled lubrication approximation of the Navier Stokes equations, and numerically study a set of solutions. In the model we include simple functions for volcanic deposition and surface erosion that change the topography over time. Scaling indicates that spreading at Amiata could still be active. The numerical solution shows that, as the central part of the edifice sinks into the weak basement, diapiric structures of the underlying formations form around the base of the volcano. Deposition of volcanic rocks within the volcano and surface erosion away from it both enhance spreading. In addition, a sloping basement may constitute a trigger for spreading and formation of trains of adjacent diapirs. As a feedback, the hot hydrothermal fluids decrease the shear strength of the anhydrites facilitating the spreading process. Finally, we observe that volcanic spreading has created ideal heat traps that constitute todays' exploited geothermal fields at Amiata. Normal faults generated by volcanic spreading, volcanic conduits, and direct contact between volcanic rocks (which host an extensive fresh

  20. Development and evaluation of a new bicycle instrument for measurements of pedal forces and power output in cycling.

    PubMed

    Stapelfeldt, B; Mornieux, G; Oberheim, R; Belli, A; Gollhofer, A

    2007-04-01

    Determination of pedal forces is a prerequisite to analyse cycling performance capability from a biomechanical point of view. Comparing existing pedal force measurement systems, there are methodological or practical limitations regarding the requirements of scientific sports performance research and enhancement. Therefore, the aim of this study was to develop and to validate a new bicycle instrument that enables pedal forces as well as power output measurements with a free choice of pedal system. The instrument (Powertec-System) is based on force transducer devices, using the Hall-Effect and being mounted between the crank and the pedal. Validation of the method was evaluated by determining the accuracy, the cross talk effect, the influence of lateral forces, the reproducibility and, finally, a possible drift under static conditions. Dynamic tests were conducted to validate the power output measurement in reference to the SRM-System. The mean error of the present system was -0.87 +/- 4.09 % and -1.86 +/- 6.61 % for, respectively, the tangential and radial direction. Cross talk, lateral force influence, reproducibility and drift mean values were < +/- 7 %, < or = 2.4 %, < 0.8 % and 0.02 N x min (-1), respectively. In dynamic conditions, the power output measurement error could be kept below 2.35 %. In conclusion, this method offers the possibility for both valid pedal forces and power output measurements. Moreover, the instrument allows measurements with every pedal system. This method has an interesting potential for biomechanical analyses in cycling research and performance enhancement. PMID:17024643