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Sample records for active force production

  1. 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

  2. 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.

  3. HRD and Productivity: Allied Forces.

    ERIC Educational Resources Information Center

    Nadler, Leonard

    1988-01-01

    The author defines productivity and discusses ways to increase productivity in the workplace, with emphasis on human resource development (HRD). He discusses the use of quality circles, participative management, and layoffs to increase productivity. (CH)

  4. The effect of swinging the arms on muscle activation and production of leg force during ski skating at different skiing speeds.

    PubMed

    Göpfert, Caroline; Lindinger, Stefan J; Ohtonen, Olli; Rapp, Walter; Müller, Erich; Linnamo, Vesa

    2016-06-01

    The study investigated the effects of arm swing during leg push-off in V2-alternate/G4 skating on neuromuscular activation and force production by the leg muscles. Nine skilled cross-country skiers performed V2-alternate skating without poles at moderate, high, and maximal speeds, both with free (SWING) and restricted arm swing (NOSWING). Maximal speed was 5% greater in SWING (P<0.01), while neuromuscular activation and produced forces did not differ between techniques. At both moderate and high speed the maximal (2% and 5%, respectively) and average (both 5%) vertical force and associated impulse (10% and 14%) were greater with SWING (all P<0.05). At high speed range of motion and angular velocity of knee flexion were 24% greater with SWING (both P<0.05), while average EMG of m. biceps femoris was 31% lower (all P<0.05) in SWING. In a similar manner, the average EMG of m. vastus medialis and m. biceps femoris were lower (17% and 32%, P<0.05) during the following knee extension. Thus, swinging the arms while performing V2-alternate can enhance both maximal speed and skiing economy at moderate and, in particularly, high speeds. PMID:27031075

  5. Perceived Submaximal Force Production in Young Adults

    ERIC Educational Resources Information Center

    Jackson, Allen W.; Ludtke, Andrew W.; Martin, Scott B.; Koziris, L. (Perry); Dishman, Rod K.

    2006-01-01

    The purpose of this investigation was to examine the force production patterns using perceived stimulus cues from 10% to 90% of maximal force. In Experiment 1, 54 men (age: 19-34 years) and 53 women (age: 18-37 years) performed leg extensions on a dynamometer at a speed of 60 degrees/s. Participants produced actual forces perceived to be 10-90% of…

  6. Task Force on Faculty Productivity.

    ERIC Educational Resources Information Center

    Hozeski, Bruce W.; And Others

    A survey was conducted of 532 faculty members and 11 administrators at Ball State University (Indiana) concerning the number of hours that faculty typically work; extent of their time devoted to teaching, research, and service/administration; how faculty workload differs by rank and status; and how faculty feel about productivity issues. Findings…

  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. 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

  10. The new science of sales force productivity.

    PubMed

    Ledingham, Dianne; Kovac, Mark; Simon, Heidi Locke

    2006-09-01

    For years, sales managers at many companies have relied on top performers and sheer numbers of sales reps to stay competitive. But while they may have squeaked by on this wing-and-a-prayer technique, their sales teams haven't thrived the way they once did. Today's most successful sales leaders are taking a more scientific approach. Savvy managers are reshaping their tactics in response to changing markets. They are reaching out to new customers in innovative ways. And they are increasing productivity by helping the reps they already have make the most of their skills and resources. Leaders who take a scientific approach to sales force effectiveness have learned to use four levers to boost their reps' productivity in a predictable and manageable way. First, they systematically target their firms' offerings, matching the right products with the right customers. Second, they optimize the automation, tools, and procedures at their disposal, providing reps with the support they need to boost sales.Third, they analyze and manage their reps' performance, measuring both internal processes and results to determine where their teams' strengths and weaknesses are. Fourth, they pay close attention to sales force deployment--how well sales, support, marketing, and delivery resources are matched to customers. These four levers can help sales leaders increase productivity across the board, the authors say, though they have the greatest impact on lower-ranked performers. The overall effect of increasing the average sales per employee can be exponential; it means a company won't have to rely on just a few talented individuals to stay competitive. This is especially important because finding and keeping star salespeople is more difficult than ever. What's more, managers who optimize the sales forces they already have can see returns they never thought possible. PMID:16967626

  11. Force production of a hovering hummingbird

    NASA Astrophysics Data System (ADS)

    Luo, Haoxiang; Song, Jialei; Hedrick, Tyson

    2013-11-01

    A three-dimensional numerical study is performed for a hovering Ruby-throated hummingbird (Archilochus colubris) based on an immersed-boundary method. To accurately model the unsteady aerodynamics, realistic 3D wing kinematics is reconstructed from high-speed images of the wing motion filmed at 1000 frames per second, resulting in 25 frames per flapping cycle. A high-resolution grid is employed to resolve the vortices shed from the wing. The results are validated by comparing the spanwise vorticity and circulation with the previous PIV data and also by calculating the average lift. The force production shows significant asymmetry with the downstroke producing lift 2.6 times as high as the upstroke, despite a nearly horizontal stroke plane. The total power consumption is around 55 W/kg, which is twice of previous estimate. In this presentation, we will discuss several mechanisms that lead to the force asymmetry, including the drag-based lift and the leading-edge vortex behavior. We will also address the role of wing-wake interaction, which appears to be different for the hummingbird than some of the insects such as fruit flies. Supported by NSF (No. CBET-0954381).

  12. Force production in the rugby union scrum.

    PubMed

    Quarrie, K L; Wilson, B D

    2000-04-01

    In this study, we examined the relationship between anthropometric, strength and power characteristics of rugby forwards, their body position when scrummaging, and their ability to apply force when scrummaging. Force applied to an instrumented scrum machine was measured for 56 players, both individually and as scrum packs. Measurements of body position for individuals were made by digitizing videotape records of the trials. Forty players subsequently had their anthropometry assessed and completed several strength and power tests. Body mass, each component of somatotype, maximal anaerobic power developed on a cycle ergometer, and isokinetic knee extension strength correlated significantly with individual scrummaging force. A regression model (P < 0.001) including body mass, mesomorphy, maximal anaerobic power and hip angle while in the scrummaging position accounted for 45% of the variance in individual scrummaging force. The packs that produced the largest scrummaging forces were, in general, characterized by a greater pack force to sum of individual force ratio than the packs producing lower forces. Our results emphasize the need for a scrum pack to develop technique and coordination as a unit to maximize scrummaging force. PMID:10824640

  13. The nature of constant and cyclic force production: unintentional force-drift characteristics.

    PubMed

    Ambike, Satyajit; Mattos, Daniela; Zatsiorsky, Vladimir M; Latash, Mark L

    2016-01-01

    We explored unintentional changes in forces during performance of constant and cyclic force-production tasks (F-tasks) after visual feedback removal. Based on earlier studies, we expected all force parameters to drop exponentially with time. We also explored possible role of working memory in the force drop phenomena. Healthy subjects performed constant or cyclic isometric F-tasks with the index finger under visual feedback. The cyclic task was paced by a metronome. Removing visual feedback resulted in a consistent force drop in constant F-tasks and a qualitatively similar drift in the mean force in the cyclic F-task. Both were slow with characteristic times of about 10-20 s. In contrast, force amplitude in the cyclic F-task increased quickly (within 1-2 s). When the subjects were asked to stop producing force for 5 s after the visual feedback disappeared and then resume force production, no downward force drift was seen in constant F-tasks, while in cyclic F-tasks, the drift of the mean force was present and an exaggerated increase in force amplitude was also observed. We conclude that while working memory limitations may influence cyclic F-tasks, their role in determining the force drift in constant F-tasks is limited. The results of both experiments are interpreted within the referent configuration hypothesis supplemented with an idea of unintentional drift of referent coordinates (RC-back-coupling) induced by differences between the referent and actual body configurations. PMID:26419663

  14. 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...

  15. 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.

  16. Knowledge of Repetitions Range Affects Force Production in Trained Females

    PubMed Central

    Halperin, Israel; Aboodarda, Saied J.; Basset, Fabien A.; Behm, David G.

    2014-01-01

    Most studies have examined pacing strategies with cyclical activities (running and cycling). It has been demonstrated that males employ different pacing strategies during repeated maximal voluntary contractions (MVCs) dependent upon a known endpoint. Since different fatiguing mechanisms have been identified between the genders, it is not known if females use comparable pacing strategies. The purpose of this study was to examine if informing female subjects regarding the number of MVCs to perform would affect force and electromyography (EMG). Twenty well-trained females completed 3 fatiguing protocols in a randomized order. In the control condition participants were informed they would perform twelve MVCs and then actually completed twelve. In the unknown condition they were not told how many MVCs to perform but were stopped after twelve. In the deception condition they were initially informed to perform 6 MVCs, but after the 6th MVC they were asked to perform a few more MVCs and were stopped after twelve. During the first 6 MVCs, forces in the deception condition were greater compared to the unknown (p = 0.021, ES = 0.65, 5%) and control (p = 0.022, ES = 0.42, 3%) conditions. No differences were found between conditions in the last 6 MVCs. A main effect for repetitions showed force deficits during the first 6 MVCs (p = 0.000, ES = 1.81, 13%) and last 6 MVCs (p = 0.05, ES = 0.34, 3%). No differences were found between conditions in biceps and triceps EMG. However, EMG decreased during the first 6 MVCs for biceps (p = 0.001, ES = 1.0, 14%) and triceps (p = 0.001, ES = 0.76, 14%) across conditions. No differences were found in the last 6 MVCs. The anticipation of performing fewer MVCs led to increased force, whereas no endpoint led to decreased force production. Key points Pacing strategies occur during repeated (fatiguing) MVCs as a function of end point expectations. Females use similar pacing strategies as previously published results with males. Without a known

  17. Force production and mechanical accommodation during convergent extension

    PubMed Central

    Zhou, Jian; Pal, Siladitya; Maiti, Spandan; Davidson, Lance A.

    2015-01-01

    Forces generated within the embryo during convergent extension (CE) must overcome mechanical resistance to push the head away from the rear. As mechanical resistance increases more than eightfold during CE and can vary twofold from individual to individual, we have proposed that developmental programs must include mechanical accommodation in order to maintain robust morphogenesis. To test this idea and investigate the processes that generate forces within early embryos, we developed a novel gel-based sensor to report force production as a tissue changes shape; we find that the mean stress produced by CE is 5.0±1.6 Pascal (Pa). Experiments with the gel-based force sensor resulted in three findings. (1) Force production and mechanical resistance can be coupled through myosin contractility. The coupling of these processes can be hidden unless affected tissues are challenged by physical constraints. (2) CE is mechanically adaptive; dorsal tissues can increase force production up to threefold to overcome a stiffer microenvironment. These findings demonstrate that mechanical accommodation can ensure robust morphogenetic movements against environmental and genetic variation that might otherwise perturb development and growth. (3) Force production is distributed between neural and mesodermal tissues in the dorsal isolate, and the notochord, a central structure involved in patterning vertebrate morphogenesis, is not required for force production during late gastrulation and early neurulation. Our findings suggest that genetic factors that coordinately alter force production and mechanical resistance are common during morphogenesis, and that their cryptic roles can be revealed when tissues are challenged by controlled biophysical constraints. PMID:25670794

  18. Production Systems. Laboratory Activities.

    ERIC Educational Resources Information Center

    Gallaway, Ann, Ed.

    This production systems guide provides teachers with learning activities for secondary students. Introductory materials include an instructional planning outline and worksheet, an outline of essential elements, domains and objectives, a course description, and a content outline. The guide contains 30 modules on the following topics: production…

  19. On the driving force of PAH production

    NASA Technical Reports Server (NTRS)

    Frenklach, Michael

    1989-01-01

    The kinetic factors affecting the production of polycyclic aromatic hydrocarbons (PAH) in high-temperature pyrolysis and combustion environments are analyzed. A lumped kinetic model representing polymerization-type growth by one irreversible step and two reversible steps is considered. It is shown that at high temperatures, PAH growth is controlled by the superequilibrium of hydrogen atoms; at low temperatures and low H2 concentrations, the PAH growth rate is proportional to the rate of the H-abstraction of a hydrogen atom from aromatic molecules; while at low temperatures and high H2 concentrations, it is controlled by the thermodynamics of the H-abstraction and the kinetics of acetylene addition to aromatic radicals. The presence of oxygen mainly affects the small-molecule reactions during the induction period.

  20. Force Production and Reactive Strength Capabilities After Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Flanagan, Eamonn P; Galvin, Lorcan; Harrison, Andrew J

    2008-01-01

    Context: Ambiguity exists in the literature regarding whether individuals can restore function to 100% after anterior cruciate ligament (ACL) reconstruction. The response of force production and reactive strength in stretch-shortening cycle activities after surgery has not been established. Objective: To compare reactive strength and force production capabilities between the involved and uninvolved legs of participants who had undergone ACL reconstruction and rehabilitation with the reactive strength and force production capabilities of a control group. Design: Repeated measures, cross-sectional. Setting: Research laboratory. Patients or Other Participants: Ten participants with ACL reconstructions who had returned to their chosen sports and 10 age-matched and activity-matched control subjects. Intervention(s): We screened the ACL group with the International Knee Documentation Committee Subjective Knee Evaluation Form and functional performance tests to measure a basic level of function. We assessed force production capabilities and reactive strength using squat, countermovement, drop, and rebound jump protocols on a force sledge apparatus. Main Outcome Measure(s): The dependent variables were flight time, peak vertical ground reaction force, leg spring stiffness, and reactive strength index. Results: No participant in the ACL group exhibited functional deficits in comparison with normative values or the control group. Using the force sledge apparatus, we found no notable differences in force production capabilities and reactive strength in the ACL group when comparing the involved with uninvolved legs or the degree of difference between legs with the control group. Conclusions: After ACL reconstruction, rehabilitated participants did not exhibit deficits in force production or reactive strength capabilities. Our results suggest that force production and reactive strength capabilities can be restored to levels comparable with the uninjured control limb and may not

  1. Force and torque production in static multifinger prehension: biomechanics and control. II. Control.

    PubMed

    Zatsiorsky, Vladimir M; Gregory, Robert W; Latash, Mark L

    2002-07-01

    The coordination of digits during combined force/torque production tasks was further studied using the data presented in the companion paper [Zatsiorsky et al. Biol Cybern this issue, Part I]. Optimization was performed using as criteria the cubic norms of (a) finger forces, (b) finger forces normalized with respect to the maximal forces measured in single-finger tasks, (c) finger forces normalized with respect to the maximal forces measured in a four-finger task, and (d) finger forces normalized with respect to the maximal moments that can be generated by the fingers. All four criteria failed to predict antagonist finger moments when these moments were not imposed by the task mechanics. Reconstruction of neural commands: The vector of neural commands c was reconstructed from the equation c=W(-1)F, where W is the finger interconnection weight matrix and F is the vector of finger forces. The neural commands ranged from zero (no voluntary force production) to one (maximal voluntary contraction). For fingers producing moments counteracting the external torque ('agonist' fingers), the intensity of the neural commands was well correlated with the relative finger forces normalized to the maximal forces in a four-finger task. When fingers produced moments in the direction of the external torque ('antagonist' fingers), the relative finger forces were always larger than those expected from the intensity of the corresponding neural commands. The individual finger forces were decomposed into forces due to 'direct' commands and forces induced by enslaving effects. Optimization of the neural commands resulted in the best correspondence between actual and predicted finger forces. The antagonist moments are, at least in part, due to enslaving effects: strong commands to agonist fingers also activated antagonist fingers. PMID:12111267

  2. Force and torque production in static multifinger prehension: biomechanics and control. II. Control

    PubMed Central

    Zatsiorsky, Vladimir M.; Gregory, Robert W.; Latash, Mark L.

    2010-01-01

    The coordination of digits during combined force/torque production tasks was further studied using the data presented in the companion paper [Zatsiorsky et al. Biol Cybern this issue, Part I]. Optimization was performed using as criteria the cubic norms of (a) finger forces, (b) finger forces normalized with respect to the maximal forces measured in single-finger tasks, (c) finger forces normalized with respect to the maximal forces measured in a four-finger task, and (d) finger forces normalized with respect to the maximal moments that can be generated by the fingers. All four criteria failed to predict antagonist finger moments when these moments were not imposed by the task mechanics. Reconstruction of neural commands: The vector of neural commands c was reconstructed from the equation c = W−1F, where W is the finger interconnection weight matrix and F is the vector of finger forces. The neural commands ranged from zero (no voluntary force production) to one (maximal voluntary contraction). For fingers producing moments counteracting the external torque (‘agonist’ fingers), the intensity of the neural commands was well correlated with the relative finger forces normalized to the maximal forces in a four-finger task. When fingers produced moments in the direction of the external torque (‘antagonist’ fingers), the relative finger forces were always larger than those expected from the intensity of the corresponding neural commands. The individual finger forces were decomposed into forces due to ‘direct’ commands and forces induced by enslaving effects. Optimization of the neural commands resulted in the best correspondence between actual and predicted finger forces. The antagonist moments are, at least in part, due to enslaving effects: strong commands to agonist fingers also activated antagonist fingers. PMID:12111267

  3. 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

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. History effect and timing of force production introduced in a skeletal muscle model.

    PubMed

    Kosterina, Natalia; Westerblad, Håkan; Eriksson, Anders

    2012-09-01

    Skeletal muscle modelling requires a detailed description of muscular force production. We have performed a series of experiments on mouse skeletal muscles to give a basis for an improved description of the muscular force production. Our previous work introduced a force modification in isometric phases, which was based on the work performed by or on the muscle during transient-length-varying contractions. Here, state-space diagrams were used to investigate the timing aspects of the force production. These show a dominant exponential nature of the force development in isometric phases of the contractions, reached after a non-exponential phase, assumed as an activation or deactivation stage and not further analysed here. The time constants of the exponential functions describing isometric force redevelopment after length variations appear to be related to the one for an initial isometric contraction, but depending on the previous history. The timing of force production calculated from the state-space diagrams was in agreement with the generally accepted muscle properties, thereby demonstrating the reliability of the method. A macroscopic muscular model consisting of a contractile element, parallel and series elastic elements was developed. The parameters from the experiment analysis, particularly the force modification after non-isometric contractions and the time constants, were reproduced by the simulations. The relationship between time constants introduced in a mechanistic model and the measured macroscale timings is discussed. PMID:22203363

  9. 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

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

    PubMed

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

    2016-09-10

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

  11. Optimisation of industrial production of low-force sensors - adhesive bonding of force-centring ball

    NASA Astrophysics Data System (ADS)

    Maeder, T.; Jacq, C.; Blot, M.; Ryser, P.

    2016-01-01

    This work addresses the issue of attaching the force-centring part (a round ball) to the load cell of a force sensor, a piezoresistive thick-film Wheatstone bridge deposited onto a ceramic cantilever. As the current soldering process requires expensive metallisation steps for both the ball and the cantilever, and subjects the solder pads used for mounting the cantilever to an additional reflow cycle, an alternative adhesive bonding process was developed, allowing both simpler production and the use of other ball materials such as ceramic and glass. The selfcentring action of solder capillary forces was ensured by structuring the adhesive so as to form a mechanical cuvette allowing centring of the ball by gravity. The selected adhesive materials exhibited good printability and bonding, as well as surviving the subsequent soldering and cleaning process steps.

  12. 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

  13. 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.

  14. Motor equivalence during multi-finger accurate force production

    PubMed Central

    Mattos, Daniela; Schöner, Gregor; Zatsiorsky, Vladimir M.; Latash, Mark L.

    2014-01-01

    We explored stability of multi-finger cyclical accurate force production action by analysis of responses to small perturbations applied to one of the fingers and inter-cycle analysis of variance. Healthy subjects performed two versions of the cyclical task, with and without an explicit target. The “inverse piano” apparatus was used to lift/lower a finger by 1 cm over 0.5 s; the subjects were always instructed to perform the task as accurate as they could at all times. Deviations in the spaces of finger forces and modes (hypothetical commands to individual fingers) were quantified in directions that did not change total force (motor equivalent) and in directions that changed the total force (non-motor equivalent). Motor equivalent deviations started immediately with the perturbation and increased progressively with time. After a sequence of lifting-lowering perturbations leading to the initial conditions, motor equivalent deviations were dominating. These phenomena were less pronounced for analysis performed with respect to the total moment of force with respect to an axis parallel to the forearm/hand. Analysis of inter-cycle variance showed consistently higher variance in a subspace that did not change the total force as compared to the variance that affected total force. We interpret the results as reflections of task-specific stability of the redundant multi-finger system. Large motor equivalent deviations suggest that reactions of the neuromotor system to a perturbation involve large changes of neural commands that do not affect salient performance variables, even during actions with the purpose to correct those salient variables. Consistency of the analyses of motor equivalence and variance analysis provides additional support for the idea of task-specific stability ensured at a neural level. PMID:25344311

  15. 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.

  16. A Home Production Activity Model.

    ERIC Educational Resources Information Center

    Beutler, Ivan F.; Owen, Alma J.

    1980-01-01

    The family is examined as a focal unit of production and a home production activity model is developed. An interdisciplinary approach is used which puts the broad range of family activities on a continuum from production to consumption. (Author/SK)

  17. 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

  18. 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.

  19. 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

  20. 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)

  1. Commercial Product Activation Using RFID

    NASA Technical Reports Server (NTRS)

    Jedrey, Thomas

    2008-01-01

    Radio-frequency identification (RFID) would be used for commercial product activation, according to a proposal. What is new here is the concept of combining RFID with activation - more specifically, using RFID for activating commercial products (principally, electronic ones) and for performing such ancillary functions as tracking individual product units on production lines, tracking shipments, and updating inventories. According to the proposal, an RFID chip would be embedded in each product. The information encoded in the chip would include a unique number for identifying the product. An RFID reader at the point of sale would record the number of the product and would write digital information to the RFID chip for either immediate activation of the product or for later interrogation and processing. To be practical, an RFID product-activation system should satisfy a number of key requirements: the system should be designed to be integrable into the inventory-tracking and the data-processing and -communication infrastructures of businesses along the entire supply chain from manufacture to retail; the system should be resistant to sophisticated hacking; activation codes should be made sufficiently complexity to minimize the probability of activating stolen products; RFID activation equipment at points of sale must be capable to two-way RF communication for the purposes of reading information from, and writing information to, embedded RFID chips; the equipment at points of sale should be easily operable by sales clerks with little or no training; the point-of-sale equipment should verify activation and provide visible and/or audible signals indicating verification or lack thereof; and, the system should be able to handle millions of products per year with minimal human intervention, among other requirements.

  2. 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

  3. 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

  4. 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

  5. 76 FR 24025 - Information Collection; Prohibition on Acquisition of Products Produced by Forced or Indentured...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-29

    ...; Prohibition on Acquisition of Products Produced by Forced or Indentured Child Labor AGENCY: Department of... acquisition of products produced by forced or indentured child labor. DATES: Submit comments on or before..., Prohibition on Acquisition of Products Produced by Forced or Indentured Child Labor, signed by the...

  6. 76 FR 42709 - Submission for OMB Review; Prohibition on Acquisition of Products Produced by Forced or...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-19

    ...; Prohibition on Acquisition of Products Produced by Forced or Indentured Child Labor AGENCY: Department of... acquisition of products produced by forced or indentured child labor. DATES: Submit comments on or before... on Acquisition of Products Produced by Forced or Indentured Child Labor, by any of the...

  7. Force and torque production in static multifinger prehension: biomechanics and control. I. Biomechanics.

    PubMed

    Zatsiorsky, Vladimir M; Gregory, Robert W; Latash, Mark L

    2002-07-01

    We studied the coordinated action of fingers during static tasks involving exertion of force and torque on a handheld object. Subjects were asked to keep a handle with an attachment that allowed for independent change of the suspended load (0.5-2.0 kg) and external torque (0.375-1.5 N m) in a vertical position while applying minimal effort. Normal and shear forces were measured from the thumb; normal forces only were measured from the four fingers. EXPERIMENTAL RESULTS: (1) the thumb shear force increased during supination efforts and decreased during pronation efforts; (2) the total moment of the normal finger forces only counterbalanced approximately 50% of the external torque, hence shear forces accounted for approximately one-half of the total torque exerted on the object; (3) the total normal force increased with external torque, and the total force magnitude did not depend on the torque direction; (4) the forces of the 'peripheral' (index and little) fingers depended mainly on the torque while the forces exerted by the 'central' (middle and ring) fingers depended both on the load and torque; (5) there was a monotonic relationship between the mechanical advantage of a finger (i.e., its moment arm during torque production) and the force produced by that finger; and (6) antagonist finger moments acting opposite to the intended direction of the total moment were always observed - at low torques the antagonist moments were as high as 40-60% of the agonist moments. MODELING: A three-zone model of coordinated finger action is suggested. In the first zone of load/torque combinations, activation of antagonist fingers (i.e., fingers that generate antagonist moments) is necessary to prevent slipping. In the second zone, the activity of agonist fingers is sufficient for preventing slips. In the third zone, the performer has freedom to choose between either activating the antagonist fingers or redistributing activities amongst the agonist fingers. The findings of this

  8. Force and torque production in static multifinger prehension: biomechanics and control. I. Biomechanics

    PubMed Central

    Zatsiorsky, Vladimir M.; Gregory, Robert W.; Latash, Mark L.

    2010-01-01

    We studied the coordinated action of fingers during static tasks involving exertion of force and torque on a handheld object. Subjects were asked to keep a handle with an attachment that allowed for independent change of the suspended load (0.5–2.0 kg) and external torque (0.375–1.5 N m) in a vertical position while applying minimal effort. Normal and shear forces were measured from the thumb; normal forces only were measured from the four fingers. Experimental results (1) the thumb shear force increased during supination efforts and decreased during pronation efforts; (2) the total moment of the normal finger forces only counterbalanced approximately 50% of the external torque, hence shear forces accounted for approximately one-half of the total torque exerted on the object; (3) the total normal force increased with external torque, and the total force magnitude did not depend on the torque direction; (4) the forces of the ‘peripheral’ (index and little) fingers depended mainly on the torque while the forces exerted by the ‘central’ (middle and ring) fingers depended both on the load and torque; (5) there was a monotonic relationship between the mechanical advantage of a finger (i.e., its moment arm during torque production) and the force produced by that finger; and (6) antagonist finger moments acting opposite to the intended direction of the total moment were always observed –at low torques the antagonist moments were as high as 40–60% of the agonist moments. Modeling A three-zone model of coordinated finger action is suggested. In the first zone of load/torque combinations, activation of antagonist fingers (i.e., fingers that generate antagonist moments) is necessary to prevent slipping. In the second zone, the activity of agonist fingers is sufficient for preventing slips. In the third zone, the performer has freedom to choose between either activating the antagonist fingers or redistributing activities amongst the agonist fingers. The

  9. 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

  10. 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

  11. The Dynamics of Voluntary Force Production in Afferented Muscle Influence Involuntary Tremor.

    PubMed

    Laine, Christopher M; Nagamori, Akira; Valero-Cuevas, Francisco J

    2016-01-01

    Voluntary control of force is always marked by some degree of error and unsteadiness. Both neural and mechanical factors contribute to these fluctuations, but how they interact to produce them is poorly understood. In this study, we identify and characterize a previously undescribed neuromechanical interaction where the dynamics of voluntary force production suffice to generate involuntary tremor. Specifically, participants were asked to produce isometric force with the index finger and use visual feedback to track a sinusoidal target spanning 5-9% of each individual's maximal voluntary force level. Force fluctuations and EMG activity over the flexor digitorum superficialis (FDS) muscle were recorded and their frequency content was analyzed as a function of target phase. Force variability in either the 1-5 or 6-15 Hz frequency ranges tended to be largest at the peaks and valleys of the target sinusoid. In those same periods, FDS EMG activity was synchronized with force fluctuations. We then constructed a physiologically-realistic computer simulation in which a muscle-tendon complex was set inside of a feedback-driven control loop. Surprisingly, the model sufficed to produce phase-dependent modulation of tremor similar to that observed in humans. Further, the gain of afferent feedback from muscle spindles was critical for appropriately amplifying and shaping this tremor. We suggest that the experimentally-induced tremor may represent the response of a viscoelastic muscle-tendon system to dynamic drive, and therefore does not fall into known categories of tremor generation, such as tremorogenic descending drive, stretch-reflex loop oscillations, motor unit behavior, or mechanical resonance. Our findings motivate future efforts to understand tremor from a perspective that considers neuromechanical coupling within the context of closed-loop control. The strategy of combining experimental recordings with physiologically-sound simulations will enable thorough exploration

  12. The Dynamics of Voluntary Force Production in Afferented Muscle Influence Involuntary Tremor

    PubMed Central

    Laine, Christopher M.; Nagamori, Akira; Valero-Cuevas, Francisco J.

    2016-01-01

    Voluntary control of force is always marked by some degree of error and unsteadiness. Both neural and mechanical factors contribute to these fluctuations, but how they interact to produce them is poorly understood. In this study, we identify and characterize a previously undescribed neuromechanical interaction where the dynamics of voluntary force production suffice to generate involuntary tremor. Specifically, participants were asked to produce isometric force with the index finger and use visual feedback to track a sinusoidal target spanning 5–9% of each individual's maximal voluntary force level. Force fluctuations and EMG activity over the flexor digitorum superficialis (FDS) muscle were recorded and their frequency content was analyzed as a function of target phase. Force variability in either the 1–5 or 6–15 Hz frequency ranges tended to be largest at the peaks and valleys of the target sinusoid. In those same periods, FDS EMG activity was synchronized with force fluctuations. We then constructed a physiologically-realistic computer simulation in which a muscle-tendon complex was set inside of a feedback-driven control loop. Surprisingly, the model sufficed to produce phase-dependent modulation of tremor similar to that observed in humans. Further, the gain of afferent feedback from muscle spindles was critical for appropriately amplifying and shaping this tremor. We suggest that the experimentally-induced tremor may represent the response of a viscoelastic muscle-tendon system to dynamic drive, and therefore does not fall into known categories of tremor generation, such as tremorogenic descending drive, stretch-reflex loop oscillations, motor unit behavior, or mechanical resonance. Our findings motivate future efforts to understand tremor from a perspective that considers neuromechanical coupling within the context of closed-loop control. The strategy of combining experimental recordings with physiologically-sound simulations will enable thorough

  13. 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

  14. 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

  15. The Adaptive Range of 1/f Isometric Force Production

    ERIC Educational Resources Information Center

    Sosnoff, Jacob J.; Valantine, Andrew D.; Newell, Karl M.

    2009-01-01

    The adaptive range of 1/f dynamics in isometric force output was investigated. Participants produced isometric force to targets with predictable demands (constant and sinusoidal) and 1/f noise waveforms (white, pink, brown, and black) that also varied in the frequency bandwidth represented in the force signal (0-4 Hz, 0-8 Hz, and 0-12 Hz). The…

  16. Production of Tunguska-sized bodies by Earth's tidal forces

    NASA Astrophysics Data System (ADS)

    Bottke, William F.; Richardson, Derek C.; Love, Stanley G.

    1998-02-01

    Tidal disruption of rubble-pile bodies (stony or icy aggregates held together by self-gravity) during close Earth encounters may produce significant numbers of Tunguska-sized (50 m) fragments. Using an N-body simulation to model encounters between strengthless, elongated, rotating, particulate bodies and the Earth, two disruption categories were found which produce small bodies: (a) "Shoemaker-Levy-9 type" catastrophic disruptions, where the progenitor is pulled into a line of similarly sized bodies, and (b) rotational disruptions, where the progenitor is distored and spun-up by tidal torque such that particles are ejected along the equator. These events occur frequently at low encounter velocities (i.e. low e and i); it is predicted that Earth's tidal forces should be effective at disrupting larger bodies into Tunguska-sized fragments in this region of phase space. By creating a map of tidal disruption outcomes for the progenitor's encounter parameters and integrating over all possible values of those parameters, it is found that the tidal production rate of Tunguska-sized bodies (upper limit) was comparable with the main-belt injection rate of Tunguska-sized bodies into resonant orbits. It is concluded that tidal disruption plays an important role in maintaining the steady-state fraction of small Earth-crossing asteroids.

  17. Molecular model for force production and transmission during vertebrate gastrulation.

    PubMed

    Pfister, Katherine; Shook, David R; Chang, Chenbei; Keller, Ray; Skoglund, Paul

    2016-02-15

    Vertebrate embryos undergo dramatic shape changes at gastrulation that require locally produced and anisotropically applied forces, yet how these forces are produced and transmitted across tissues remains unclear. We show that depletion of myosin regulatory light chain (RLC) levels in the embryo blocks force generation at gastrulation through two distinct mechanisms: destabilizing the myosin II (MII) hexameric complex and inhibiting MII contractility. Molecular dissection of these two mechanisms demonstrates that normal convergence force generation requires MII contractility and we identify a set of molecular phenotypes correlated with both this failure of convergence force generation in explants and of blastopore closure in whole embryos. These include reduced rates of actin movement, alterations in C-cadherin dynamics and a reduction in the number of polarized lamellipodia on intercalating cells. By examining the spatial relationship between C-cadherin and actomyosin we also find evidence for formation of transcellular linear arrays incorporating these proteins that could transmit mediolaterally oriented tensional forces. These data combine to suggest a multistep model to explain how cell intercalation can occur against a force gradient to generate axial extension forces. First, polarized lamellipodia extend mediolaterally and make new C-cadherin-based contacts with neighboring mesodermal cell bodies. Second, lamellipodial flow of actin coalesces into a tension-bearing, MII-contractility-dependent node-and-cable actin network in the cell body cortex. And third, this actomyosin network contracts to generate mediolateral convergence forces in the context of these transcellular arrays. PMID:26884399

  18. 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

  19. Knee extension fatigue attenuates repeated force production of the elbow flexors.

    PubMed

    Halperin, Israel; Aboodarda, Saied J; Behm, David G

    2014-01-01

    Non-local muscle fatigue has been demonstrated with unilateral activities, where fatiguing one limb alters opposite limb forces. Fewer studies have examined if non-local fatigue occurs with unrelated muscles. The purpose of this study was to investigate if knee extensors fatigue alters elbow flexors force and electromyography (EMG) activity. Eighteen males completed a control and fatiguing session (randomised). Blood lactate was initially sampled followed by three maximal voluntary contractions (MVC) with the elbow flexors and two with the knee extensors. Thereafter, subjects either sat (control) or performed five sets of bilateral dynamic knee extensions to exhaustion using a load equal to the dominant limb MVC (1-min rest between sets). Immediately afterwards, subjects were assessed for blood lactate and unilateral knee extensors MVC, and after 1 min performed a single unilateral elbow flexor MVC. Two minutes later, subjects performed 12 unilateral elbow flexor MVCs (5 s contraction/10 s rest) followed by a third blood lactate test. Compared to control, knee extensor force dropped by 35% (p < 0.001; ES = 1.6) and blood lactate increased by 18% (p < 0.001; ES = 2.8). Elbow flexor forces were lower after the fatiguing protocol only during the last five MVCs (p < 0.05; ES = ∼ 0.58; ∼ 5%). No changes occurred between conditions in EMG. Elbow flexor forces significantly decreased after knee extensors fatigue. The effect was revealed during the later stages of the repeated MVCs protocol, demonstrating that non-local fatigue may have a stronger effect on repeated rather than on single attempts of maximal force production. PMID:24766625

  20. Particle Production by Tidal Forces, and the Energy - Tensor

    NASA Astrophysics Data System (ADS)

    Massacand, Christophe Maurice Jean-Baptiste

    The quantum production of spinless particles, < n_{k}(t)>, and of energy-momentum-stress, < T^{{a}{b}}(P) >, by the tidal forces of classical curved space-time are investigated in this thesis. In a first part we consider the test case of 1+1 dimensions. Our computations are finite step by step, the predicted evolution of the energy-momentum tensor < T^{ a b} > and of the spectral energy density e_{k}< n_{k }> are consistent with each other throughout curved space-time, < T^ { a b}> is covariantly conserved and has the standard trace anomaly R/24 pi for massless particles. The two chiralities, right-goers versus left-goers, are decoupled, the total < T^{{a} {b}}> is the sum of the chiral parts. We apply our methods to four problems: (1) The Rindler problem. (2) An inhomogeneous patch of curvature produces a burst of energy-momentum and of particles. (3) We compute the quantum production of energy density and pressure for a quantum field in external Friedmann-Robertson -Walker space-times in 1+1 dimensions. (4) We consider the gravitational field of a collapsing shell of classical matter in 3+1 dimensions, and we compute the production of Hawking radiation everywhere inside a linear wave guide in the radial direction. In a second part, we compute the energy density and pressures from a quantum scalar field propagating in the external field of a (3+1)-dimensional, spherically symmetric, static geometry with flat spatial sections. We consider only the (l = 0)-sector of the scalar field. The initial state of the quantum field is the gauge invariant vacuum on one of these hypersurface. Our computations are finite step by step. For the pressures we use the covariant conservation of T^{mu nu} and its four-dimensional trace. We apply our results to the case of the gravitational potential due to an homogeneous spherical body. At late times, i.e. when all switch-on effects are far away from the body, the results are that a static cloud of energy and pressure is formed inside

  1. 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

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. Influence of Emotion on the Control of Low-Level Force Production

    ERIC Educational Resources Information Center

    Naugle, Kelly M.; Coombes, Stephen A.; Cauraugh, James H.; Janelle, Christopher M.

    2012-01-01

    The accuracy and variability of a sustained low-level force contraction (2% of maximum voluntary contraction) was measured while participants viewed unpleasant, pleasant, and neutral images during a feedback occluded force control task. Exposure to pleasant and unpleasant images led to a relative increase in force production but did not alter the…

  7. Motor control hierarchy in joint action that involves bimanual force production

    PubMed Central

    Masumoto, Junya

    2015-01-01

    The concept of hierarchical motor control has been viewed as a means of progressively decreasing the number of variables manipulated by each higher control level. We tested the hypothesis that turning an individual bimanual force-production task into a joint (two-participant) force-production task would lead to positive correlation between forces produced by the two hands of the individual participant (symmetric strategy) to enable negative correlation between forces produced by two participants (complementary strategy). The present study consisted of individual and joint tasks that involved both unimanual and bimanual conditions. In the joint task, 10 pairs of participants produced periodic isometric forces, such that the sum of forces that they produced matched a target force cycling between 5% and 10% of maximum voluntary contraction at 1 Hz. In the individual task, individuals attempted to match the same target force. In the joint bimanual condition, the two hands of each participant adopted a symmetric strategy of force, whereas the two participants adopted a complementary strategy of force, highlighting that the bimanual action behaved as a low level of a hierarchy, whereas the joint action behaved as an upper level. The complementary force production was greater interpersonally than intrapersonally. However, whereas the coherence was highest at 1 Hz in all conditions, the frequency synchrony was stronger intrapersonally than interpersonally. Moreover, whereas the bimanual action exhibited a smaller error and variability of force than the unimanual action, the joint action exhibited a less-variable interval and force than the individual action. PMID:25904710

  8. Symmetrical and asymmetrical influences on force production in 1:2 and 2:1 bimanual force coordination tasks.

    PubMed

    Kennedy, Deanna M; Rhee, Joohyun; Shea, Charles H

    2016-01-01

    Results from a recent experiment (Kennedy et al. in Exp Brain Res 233:181-195, 2015) indicated consistent and identifiable distortion of the left limb forces that could be attributable to the production of right limb forces during a multi-frequency bimanual force task. However, distortions in the forces produced by the right limb that could be attributable to the production of force in the left limb were not observed. The present experiment was designed to replicate this finding and determine whether the influence of force produced by one limb on the contralateral limb is the result of the limb assigned the faster frequency on the limb performing the slower frequency or a bias associated with limb dominance. Participants (N = 10) were required to rhythmically coordinate a pattern of isometric forces in a 1:1, 1:2, or 2:1 coordination pattern. The 1:2 task required the right limb to perform the faster rhythm, while the 2:1 task required the left limb to perform the faster rhythm. The 1:1 task was used as a control. Participants performed 13 practice trials and 1 test trial per task. Lissajous displays were provided to guide performance. If the limb assigned the faster frequency was responsible for the distortions observed in the contralateral limb, it was hypothesized that distortions would only be observed in the force trace of the limb producing the slower pattern of force. If a bias associated with limb dominance was responsible for the distortions observed in the contralateral limb, it was hypothesized that in right-limb-dominant participants the right limb would influence the left limb, regardless of limb assignment. Replicating the results of the previous experiment, only distortions in the left limb were observed in the 1:2 coordination task that could be attributed to the production of force by the right limb. However, identifiable distortions were observed in the force produced by both the left and right limb in the 2:1 coordination task. Observed

  9. Corticospinal excitability during imagined and observed dynamic force production tasks: effortfulness matters.

    PubMed

    Helm, F; Marinovic, W; Krüger, B; Munzert, J; Riek, S

    2015-04-01

    Research on motor imagery and action observation has become increasingly important in recent years particularly because of its potential benefits for movement rehabilitation and the optimization of athletic performance (Munzert et al., 2009). Motor execution, motor imagery, and action observation have been shown to rely largely on a similar neural network in motor and motor-related cortical areas (Jeannerod, 2001). Given that motor imagery is a covert stage of an action and its characteristics, it has been assumed that modifying the motor task in terms of, for example, effort will impact neural activity. With this background, the present study examined how different force requirements influence corticospinal excitability (CSE) and intracortical facilitation during motor imagery and action observation of a repetitive movement (dynamic force production). Participants were instructed to kinesthetically imagine or observe an abduction/adduction movement of the right index finger that differed in terms of force requirements. Trials were carried out with single- or paired-pulse transcranial magnetic stimulation. Surface electromyography was recorded from the first dorsal interosseous (FDI) and the abductor digiti minimi (ADM). As expected, results showed a significant main effect on mean peak-to-peak motor-evoked potential (MEP) amplitudes in FDI but no differences in MEP amplitudes in ADM muscle. Participants' mean peak-to-peak MEPs increased when the force requirements (movement effort) of the imagined or observed action were increased. This reveals an impact of the imagined and observed force requirements of repetitive movements on CSE. It is concluded that this effect might be due to stronger motor neuron recruitment for motor imagery and action observation with an additional load. That would imply that the modification of motor parameters in movements such as force requirements modulates CSE. PMID:25639231

  10. 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

  11. 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.

  12. Evidence that myosin does not contribute to force production in chromosome movement

    PubMed Central

    1982-01-01

    Antibody against cytoplasmic myosin, when microinjected into actively dividing cells, provides a physiological test for the role of actin and myosin in chromosome movement. Anti-Asterias egg myosin, characterized by Mabuchi and Okuno (1977, J. Cell Biol., 74:251), completely and specifically inhibits the actin activated Mg++ -ATPase of myosin in vitro and, when microinjected, inhibits cytokinesis in vivo. Here, we demonstrate that microinjected antibody has no observable effect on the rate or extent of anaphase chromosome movements. Neither central spindle elongation nor chromosomal fiber shortening is affected by doses up to eightfold higher than those require to uniformly inhibit cytokinesis in all injected cells. We calculate that such doses are sufficient to completely inhibit myosin ATPase activity in these cells. Cells injected with buffer alone, with myosin-absorbed antibody, or with nonimmune gamma-globulin, proceed normally through both mitosis and cytokinesis. Control gamma-globulin, labeled with fluorescein, diffuses to homogeneity throughout the cytoplasm in 2-4 min and remains uniformly distributed. Antibody is not excluded from the spindle region. Prometaphase chromosome movements, fertilization, pronuclear migration, and pronuclear fusion are also unaffected by microinjected antimyosin. These experiments demonstrate that antimyosin blocks the actomyosin interaction thought to be responsible for force production in cytokinesis but has no effect on mitotic or meiotic chromosome motion. They provide direct physiological evidence that myosin is not involved in force production for chromosome movement. PMID:6181080

  13. Sprint Acceleration Mechanics: The Major Role of Hamstrings in Horizontal Force Production

    PubMed Central

    Morin, Jean-Benoît; Gimenez, Philippe; Edouard, Pascal; Arnal, Pierrick; Jiménez-Reyes, Pedro; Samozino, Pierre; Brughelli, Matt; Mendiguchia, Jurdan

    2015-01-01

    Recent literature supports the importance of horizontal ground reaction force (GRF) production for sprint acceleration performance. Modeling and clinical studies have shown that the hip extensors are very likely contributors to sprint acceleration performance. We experimentally tested the role of the hip extensors in horizontal GRF production during short, maximal, treadmill sprint accelerations. Torque capabilities of the knee and hip extensors and flexors were assessed using an isokinetic dynamometer in 14 males familiar with sprint running. Then, during 6-s sprints on an instrumented motorized treadmill, horizontal and vertical GRF were synchronized with electromyographic (EMG) activity of the vastus lateralis, rectus femoris, biceps femoris, and gluteus maximus averaged over the first half of support, entire support, entire swing and end-of-swing phases. No significant correlations were found between isokinetic or EMG variables and horizontal GRF. Multiple linear regression analysis showed a significant relationship (P = 0.024) between horizontal GRF and the combination of biceps femoris EMG activity during the end of the swing and the knee flexors eccentric peak torque. In conclusion, subjects who produced the greatest amount of horizontal force were both able to highly activate their hamstring muscles just before ground contact and present high eccentric hamstring peak torque capability. PMID:26733889

  14. Correlation of Force Production with Apoptosis in Tissue Dynamics

    NASA Astrophysics Data System (ADS)

    Toyama, Yusuke; Peralta, Xomalin; Venakides, Stephanos; Kiehart, Daniel; Edwards, Glenn

    2007-03-01

    To understand embryo morphogenesis, it is necessary to know the force distribution in the various tissues. Since cells are largely inaccessible to mechanical probes in vivo, measurements of the net forces exerted by cells are challenging. The combination of experimental and theoretical approaches has proven to improve our understanding of these forces. A steerable UV-laser microbeam was used to probe the forces and the resulting kinematics were monitored with confocal microscopy. Dorsal closure is a developmental stage in Drosophila embryogenesis, where the dynamics are a consequence of four biological processes [1]. During this stage, cells that have outlived their usefulness undergo apoptosis, a biological process also known as programmed cell death for cells. Apoptotic events were decreased with genetic techniques or increased by irradiation with a UV-C lamp. We present experimental evidence for force generation correlating with apoptosis. This research has been supported by the NIH (GM33830 and GM61240). [1] M. S. Hutson, et al. Science, 300, 145 (2003).

  15. Flagellar force production during regeneration in Chlamydomonas reinhardtii

    NASA Astrophysics Data System (ADS)

    Yukich, John N.; Clodfelter, Catherine; Bernd, Karen K.

    2009-11-01

    Several respiratory, digestive, and reproductive disorders originate with motional dysfunction of cilia and flagella. The usefulness of cilia and flagella is understood, but the internal mechanism for creating their breast stroke-like motion is not. This study reports on standardization of calibration, trapping and cell movement recording methods. Our techniques permit us to measure the flagellar swimming force of Chlamydomonas during flagella regeneration. We find that as flagella length increases, the flagellar force is maximized after 50% of full length is achieved except for a significant dip at 75% of full length. These results raise many questions regarding the flagella infrastructure.

  16. Age Differences in Noise and Variability of Isometric Force Production.

    ERIC Educational Resources Information Center

    Deutsch, Katherine M.; Newell, Karl M.

    2001-01-01

    Examined whether age-related improvements in children's motor performance result from reduced noise in the output of the sensorimotor system. Found that performance improved with age. The force output signal exhibited increased irregularity and a more broadband frequency profile with increasing age under feedback. There were no age differences in…

  17. Force feedback coupling with dynamics for physical simulation of product assembly and operation performance

    NASA Astrophysics Data System (ADS)

    Liu, Zhenyu; Tan, Jianrong; Duan, Guifang; Fu, Yun

    2015-01-01

    Most existing force feedback methods are still difficult to meet the requirements of real-time force calculation in virtual assembly and operation with complex objects. In addition, there is often an assumption that the controlled objects are completely free and the target object is only completely fixed or free, thus, the dynamics of the kinematic chain where the controlled objects are located are neglected during the physical simulation of the product manipulation with force feedback interaction. This paper proposes a physical simulation method of product assembly and operation manipulation based on statistically learned contact force prediction model and the coupling of force feedback and dynamics. In the proposed method, based on hidden Markov model (HMM) and local weighting learning (LWL), contact force prediction model is constructed, which can estimate the contact force in real time during interaction. Based on computational load balance model, the computing resources are dynamically assigned and the dynamics integral step is optimized. In addition, smoothing process is performed to the force feedback on the synchronization points. Consequently, we can solve the coupling and synchronization problems of high-frequency feedback force servo, low-frequency dynamics solver servo and scene rendering servo, and realize highly stable and accurate force feedback in the physical simulation of product assembly and operation manipulation. This research proposes a physical simulation method of product assembly and operation manipulation.

  18. 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

  19. US Air Force Space Weather Products Rapid Prototyping Efforts - Solar Radio Background/Burst Effects and Meteor Effects Products

    NASA Astrophysics Data System (ADS)

    Quigley, S.; Scro, K.

    2001-12-01

    The Space Vehicles Directorate of the Air Force Research Laboratory (AFRL/VSB) has joined efforts with the Technology Applications Division of the Space and Missile Systems Center (SMC Det 11/CIT) to rapidly transition space weather research into prototype, operational, system-impact products. These Rapid Prototyping Center (RPC) products are used to analyze, specify, and forecast the effects of the near-earth space environment on Department of Defense systems and communications. A summary of RPC activity is provided. Emphasis will be placed on current products under development, to include Solar Radio Background/Burst Effects (SoRBE) and Meteor Effects (ME) products. These will be added to real-time operations in the near future. SoRBE specifies the detrimental interference effects of background and event-level solar radio output on radar observations and satellite communications. ME will provide general meteor shower "nowcast" and forecast information, along with more specific meteor and meteor shower impact, radar clutter, and bolide (exploding meteor) effects. A brief overview of recently delivered products: Radar Auroral Clutter, Satellite Scintillation, HF Illumination, and GPS Single-Frequency Error Maps will also be provided.

  20. Effects of resistance training on tendon mechanical properties and rapid force production in prepubertal children

    PubMed Central

    Waugh, C. M.; Korff, T.; Fath, F.

    2014-01-01

    Children develop lower levels of muscle force, and at slower rates, than adults. Although strength training in children is expected to reduce this differential, a synchronous adaptation in the tendon must be achieved to ensure forces continue to be transmitted to the skeleton with efficiency while minimizing the risk of strain-related tendon injury. We hypothesized that resistance training (RT) would alter tendon mechanical properties in children concomitantly with changes in force production characteristics. Twenty prepubertal children (age 8.9 ± 0.3 yr) were equally divided into control (nontraining) and experimental (training) groups. The training group completed a 10-wk RT intervention consisting of 2–3 sets of 8–15 plantar flexion contractions performed twice weekly on a recumbent calf-raise machine. Achilles tendon properties (cross-sectional area, elongation, stress, strain, stiffness, and Young's modulus), electromechanical delay (EMD; time between the onset of muscle activity and force), rate of force development (RFD; slope of the force-time curve), and rate of electromyographic (EMG) increase (REI; slope of the EMG time curve) were measured before and after RT. Tendon stiffness and Young's modulus increased significantly after RT in the experimental group only (∼29% and ∼25%, respectively); all other tendon properties were not significantly altered, although there were mean decreases in both peak tendon strain and strain at a given force level (14% and 24%, respectively; not significant) which may have implications for tendon injury risk and muscle fiber mechanics. A decrease of ∼13% in EMD was found after RT for the experimental group, which paralleled the increase in tendon stiffness (r = −0.59); however, RFD and REI were unchanged. The present data show that the Achilles tendon adapts to RT in prepubertal children and is paralleled by a change in EMD, although the magnitude of this change did not appear to be sufficient to influence RFD

  1. Synoptic events force biological productivity in Patagonian fjord ecosystems

    NASA Astrophysics Data System (ADS)

    Daneri, Giovanni

    2016-04-01

    The annual cycle of primary productivity of the Patagonian fjords has, to date, been described as a two phase system consisting of a short non productive winter phase (during June and July) and a productive phase extending from late winter (August) to autumn (May). Low levels of primary production, phytoplankton biomass and high concentrations of surface nutrients have been described as characterizing winter conditions while pulsed productivity events typifies the productivity pattern during the extended productive season. Pulsed productivity events characterize coastal waters where inorganic nutrients in surface layers are replenished following periods of intensive utilization by autotrophs. Freshwater input in Patagonian fjords in southern Chile (41-55°S) results in one of the largest estuarine regions worldwide. Here strong haline water column stratification prevents nutrient mixing to the surface layers thus potentially shutting off algal production. Our working hypothesis considered that in order to reconcile the observed pulsed productivity pattern, periodic breaking (associated to surface nutrient replenishment) and re-establishment of estuarine conditions (associated to water column stratification) would be required. Up to now however our understanding of the physical processes that control water column conditions in the Patagonian fjord area has been extremely limited. Here we present evidence linking the passage of synoptic low pressure fronts to pulsed productivity events in the Patagonian fjord area. These front controls and influence local processes of interaction between the fjord and the atmosphere generating a rapid water column response. In the specific case of the Puyuhuapi fjord we have been able to show that such synoptic fronts induce surface flow reversal and water column mixing. Phytoplankton blooming occurs after the passage of the synoptic front once calmer conditions prevail and estuarine conditions are re established. The occurrence of

  2. The Sensitivity of Simulated Ocean Biogeochemistry to Forcing Fields Derived from NCEP and MERRA Reanalysis Products

    NASA Technical Reports Server (NTRS)

    Gregg, Watson; Casey, Nancy

    2010-01-01

    Ocean biogeochemistry models are typically forced by atmospheric and oceanic data derived from reanalysis products. For the NASA Ocean Biogeochemistry Model (NOBM) such reanalysis forcing fields include: surface wind stress, sea surface temperature, ice distributions, shortwave radiation, surface wind speeds and surface atmospheric pressure. Additionally, proper computation of ocean irradiance requires reanalysis products of relative humidity and precipitable water (in addition to aerosol and cloud information which is derived from satellite data). The question posed here is, does the choice of reanalysis products make a difference in the representation of ocean biology and biogeochemistry? NOBM was forced by NCEP and MERRA reanalysis products for the period 2002-2009. We find that in 2009 global distributions and abundances of biological variables (total chlorophyll and nutrients) and carbon (dissolved inorganic and organic carbon and surface pCO2) were similar between the two different forcing fields. Global statistical comparisons with satellite and in situ data also showed negligible differences.

  3. Error compensation during finger force production after one- and four-finger voluntarily fatiguing exercise.

    PubMed

    Kruger, Eric S; Hoopes, Josh A; Cordial, Rory J; Li, Sheng

    2007-08-01

    The effect of muscle fatigue on error compensation strategies during multi-finger ramp force production tasks was investigated. Thirteen young, healthy subjects were instructed to produce a total force with four fingers of the right hand to accurately match a visually displayed template. The template consisted of a 3-s waiting period, a 3-s ramp force production [from 0 to 30% maximal voluntary contraction (MVC)], and a 3-s constant force production. A series of 12 ramp trials was performed before and after fatigue. Fatigue was induced by a 60-s maximal isometric force production with either the index-finger only or with all four fingers during two separate testing sessions. The average percent of drop was 38.2% in the MVC of the index finger after index-finger fatiguing exercise and 38.3% in the MVC of all fingers after four-finger fatiguing exercise. The ability of individual fingers to compensate for each other's errors in order for the total force to match the preset template was quantified as the error compensation index (ECI), i.e., the ratio of the sum of variances of individual finger forces and the variance of the total force. By comparing pre- and post-fatigue performance during four-finger ramp force production, we observed that the variance of the total force was not significantly changed after one- or four-finger fatiguing exercise. The ECI significantly decreased after four-finger fatiguing exercise, especially during the last second of the ramp; while the ECI remained unchanged after index finger single-finger fatiguing exercise. These results suggest that the central nervous system is able to utilize the abundant degrees of freedom to compensate for partial impairment of the motor apparatus induced by muscle fatigue to maintain the desired performance. However, this ability is significantly decreased when all elements of the motor apparatus are impaired. PMID:17443316

  4. 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

  5. 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

  6. Age-related changes in multifinger synergies in accurate moment of force production tasks

    PubMed Central

    Olafsdottir, Halla; Zhang, Wei; Zatsiorsky, Vladimir M.; Latash, Mark L.

    2010-01-01

    The purpose of this investigation was to document and quantify age-related differences in the coordination of fingers during a task that required production of an accurate time profile of the total moment of force by the four fingers of a hand. We hypothesized that elderly subjects would show a decreased ability to stabilize a time profile of the total moment of force, leading to larger indexes of moment variability compared with young subjects. The subjects followed a trapezoidal template on a computer screen by producing a time profile of the total moment of force while pressing down on force sensors with the four fingers of the right (dominant) hand. To quantify synergies, we used the framework of the uncontrolled manifold hypothesis. The elderly subjects produced larger total force, larger variance of both total force and total moment of force, and larger involvement of fingers that produced moment of force against the required moment direction (antagonist moment). This was particularly prominent during supination efforts. Young subjects showed covariation of commands to fingers across trials that stabilized the moment of total force (moment-stabilizing synergy), while elderly subjects failed to do so. Both subject groups showed similar indexes of covariation of commands to the fingers that stabilized the time profile of the total force. The lack of moment-stabilizing synergies may be causally related to the documented impairment of hand function with age. PMID:17204576

  7. Forces Shaping Future U.S. Coal Production and Use

    USGS Publications Warehouse

    Attanasi, E.D.; Pierce, Brenda S.

    2001-01-01

    More than half of the electricity in the United States is generated by coal-fired powerplants. U.S. coal producers sell almost 90 percent of their product for electricity generation, and so, the future of the U.S. coal industry will be determined by the future of coal-fired electricity-generation plants. The U.S. Geological Survey (USGS) is completing a National Coal Resource Assessment (NCRA) of five major coal-producing regions of the United States (fig. 1): (1) the Appalachian Basin, (2) the Illinois Basin, (3) the Gulf Coast, (4) the Colorado Plateau, and (5) the Northern Rocky Mountains and Great Plains. The Powder River and Williston Basins are the principal producing areas of the Northern Rocky Mountains and Great Plains region.

  8. Microtubule C-Terminal Tails Can Change Characteristics of Motor Force Production.

    PubMed

    Shojania Feizabadi, Mitra; Janakaloti Narayanareddy, Babu Reddy; Vadpey, Omid; Jun, Yonggun; Chapman, Dail; Rosenfeld, Steven; Gross, Steven P

    2015-10-01

    Control of intracellular transport is poorly understood, and functional ramifications of tubulin isoform differences between cell types are mostly unexplored. Motors' force production and detachment kinetics are critical for their group function, but how microtubule (MT) details affect these properties--if at all--is unknown. We investigated these questions using both a vesicular transport human kinesin, kinesin-1, and also a mitotic kinesin likely optimized for group function, kinesin-5, moving along either bovine brain or MCF7(breast cancer) MTs. We found that kinesin-1 functioned similarly on the two sets of MTs--in particular, its mean force production was approximately the same, though due to its previously reported decreased processivity, the mean duration of kinesin-1 force production was slightly decreased on MCF7 MTs. In contrast, kinesin-5's function changed dramatically on MCF7 MTs: its average detachment force was reduced and its force-velocity curve was different. In spite of the reduced detachment force, the force-velocity alteration surprisingly improved high-load group function for kinesin-5 on the cancer-cell MTs, potentially contributing to functions such as spindle-mediated chromosome separation. Significant differences were previously reported for C-terminal tubulin tails in MCF7 versus bovine brain tubulin. Consistent with this difference being functionally important, elimination of the tails made transport along the two sets of MTs similar. PMID:26094820

  9. 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.

  10. Sensitivity of coastal polynyas and high-salinity shelf water production in the Ross Sea, Antarctica, to the atmospheric forcing

    NASA Astrophysics Data System (ADS)

    Mathiot, Pierre; Jourdain, Nicolas C.; Barnier, Bernard; Gallée, Hubert; Molines, Jean Marc; Le Sommer, Julien; Penduff, Thierry

    2012-05-01

    Coastal polynyas around Antarctica are the place of intense air-sea exchanges which eventually lead to the formation of high-salinity shelf waters (HSSW) over continental shelves. Here, the influence of atmospheric forcing on coastal polynyas in the Ross Sea is studied by contrasting the response of a regional ocean/sea-ice circulation model to two different atmospheric forcing sets. A first forcing (DFS3) is based on ERA40 atmospheric surface variables and satellite products. A second forcing (MAR) is produced on the basis of ERA40 with a dynamical downscaling procedure. As compared to DFS3, MAR forcing is shown to improve substantially the representation of small-scale patterns of coastal winds with stronger katabatic winds along the coast. The response of the ocean/sea-ice model to the two forcing sets shows that the MAR forcing improves substantially the geographical distribution of polynyas in the Ross Sea. With the MAR forcing, the polynya season is also shown to last longer with a greater ice-production rate. As a consequence, a greater flow of dense water out of the polynyas is found with the MAR forcing and the properties of HSSW are notably improved as compared to the DFS3 forcing. The factors contributing to the activity of Terra Nova Bay and Ross Ice Shelf polynyas in the model are studied in detail. The general picture that emerges from our simulations is that the properties of HSSW are mostly set by brine rejection when the polynya season resume. We found that coastal polynyas in the Ross Sea export about 0.4 Sv of HSSW which then flows along three separate channels over the Ross Shelf. A 6-month time lag is observed between the peak of activity of polynyas and the maximum transport across the sills in the channels with a maximum transport of about 1 Sv in February. This lag corresponds to the time it takes to the newly formed HSSW to spread from the polynya to the sills (at a speed of nearly 2 cm s-1).

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. 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

  16. 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

  17. Dissociation of brain areas associated with force production and stabilization during manipulation of unstable objects

    PubMed Central

    de Manzano, Örjan; Vollmer, Brigitte; Forsman, Lea; Valero-Cuevas, Francisco J.; Ullén, Fredrik; Forssberg, Hans

    2014-01-01

    Multifinger dexterous manipulation of unstable or deformable objects requires control of both direction and magnitude of fingertip force vectors. Our aim was to study the neuroanatomical correlates of these two distinct control functions. Brain activity was measured using functional magnetic resonance imaging while 16 male subjects (age: 26–42, M = 32, SD ± 4 years) compressed four springs representing a 2 × 2 factorial design with two levels of force and instability requirements. Significant activations associated with higher instability were located bilaterally in the precentral gyri, the postcentral gyrus, and the cerebellum. In the main effect for high force, activity was found in areas located in the primary motor regions contralateral to the active hand and bilaterally in the cerebellum. An overlap in activation between the two main effects was found bilaterally in the cerebellum (lobule VI). This study not only confirms a recently described bilateral fronto-parieto-cerebellar network for manipulation of increasingly unstable objects, but critically extends our understanding by describing its differentiated modulation with both force magnitude and instability requirements. Our results, therefore, expose a previously unrecognized and context-sensitive system of brain regions that enable dexterous manipulation for different force magnitude and instability requirements of the task. PMID:22038714

  18. Coupling of Retrograde Flow to Force Production During Malaria Parasite Migration.

    PubMed

    Quadt, Katharina A; Streichfuss, Martin; Moreau, Catherine A; Spatz, Joachim P; Frischknecht, Friedrich

    2016-02-23

    Migration of malaria parasites is powered by a myosin motor that moves actin filaments, which in turn link to adhesive proteins spanning the plasma membrane. The retrograde flow of these adhesins appears to be coupled to forward locomotion. However, the contact dynamics between the parasite and the substrate as well as the generation of forces are complex and their relation to retrograde flow is unclear. Using optical tweezers we found retrograde flow rates up to 15 μm/s contrasting with parasite average speeds of 1-2 μm/s. We found that a surface protein, TLP, functions in reducing retrograde flow for the buildup of adhesive force and that actin dynamics appear optimized for the generation of force but not for maximizing the speed of retrograde flow. These data uncover that TLP acts by modulating actin dynamics or actin filament organization and couples retrograde flow to force production in malaria parasites. PMID:26792112

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  20. Natural products and anti-inflammatory activity.

    PubMed

    Yuan, Gaofeng; Wahlqvist, Mark L; He, Guoqing; Yang, Min; Li, Duo

    2006-01-01

    The aim of this review paper was to summarise some commonly available natural products and their anti-inflammatory activity. We have collected data from MEDLINE, Current Contents and scientific journals, which included 92 publications. There are numerous natural products detailed in this literature; however we have summarized a few of the most commonly available and potent ones. In this paper, the natural products with anti-inflammatory activity including curcumin, parthenolide, cucurbitacins, 1,8-cineole, pseudopterosins, lyprinol, bromelain, flavonoids, saponins, marine sponge natural products and Boswellia serrata gum resin were reviewed. Natural products play a significant role in human health in relation to the prevention and treatment of inflammatory conditions. Further studies are being conducted to investigate the mechanism of action, metabolism, safety and long term side effect of these natural products, as well as interactions between these natural products with food and drug components. PMID:16672197

  1. 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

  2. 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

  3. 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

  4. 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

  5. Sensitivity of Simulated Global Ocean Carbon Flux Estimates to Forcing by Reanalysis Products

    NASA Technical Reports Server (NTRS)

    Gregg, Watson W.; Casey, Nancy W.; Rousseaux, Cecile S.

    2015-01-01

    Reanalysis products from MERRA, NCEP2, NCEP1, and ECMWF were used to force an established ocean biogeochemical model to estimate air-sea carbon fluxes (FCO2) and partial pressure of carbon dioxide (pCO2) in the global oceans. Global air-sea carbon fluxes and pCO2 were relatively insensitive to the choice of forcing reanalysis. All global FCO2 estimates from the model forced by the four different reanalyses were within 20% of in situ estimates (MERRA and NCEP1 were within 7%), and all models exhibited statistically significant positive correlations with in situ estimates across the 12 major oceanographic basins. Global pCO2 estimates were within 1% of in situ estimates with ECMWF being the outlier at 0.6%. Basin correlations were similar to FCO2. There were, however, substantial departures among basin estimates from the different reanalysis forcings. The high latitudes and tropics had the largest ranges in estimated fluxes among the reanalyses. Regional pCO2 differences among the reanalysis forcings were muted relative to the FCO2 results. No individual reanalysis was uniformly better or worse in the major oceanographic basins. The results provide information on the characterization of uncertainty in ocean carbon models due to choice of reanalysis forcing.

  6. How wing kinematics affect power requirements and aerodynamic force production in a robotic bat wing.

    PubMed

    Bahlman, Joseph W; Swartz, Sharon M; Breuer, Kenneth S

    2014-06-01

    Bats display a wide variety of behaviors that require different amounts of aerodynamic force. To control and modulate aerodynamic force, bats change wing kinematics, which, in turn, may change the power required for wing motion. There are many kinematic mechanisms that bats, and other flapping animals, can use to increase aerodynamic force, e.g. increasing wingbeat frequency or amplitude. However, we do not know if there is a difference in energetic cost between these different kinematic mechanisms. To assess the relationship between mechanical power input and aerodynamic force output across different isolated kinematic parameters, we programmed a robotic bat wing to flap over a range of kinematic parameters and measured aerodynamic force and mechanical power. We systematically varied five kinematic parameters: wingbeat frequency, wingbeat amplitude, stroke plane angle, downstroke ratio, and wing folding. Kinematic values were based on observed values from free flying Cynopterus brachyotis, the species on which the robot was based. We describe how lift, thrust, and power change with increases in each kinematic variable. We compare the power costs associated with generating additional force through the four kinematic mechanisms controlled at the shoulder, and show that all four mechanisms require approximately the same power to generate a given force. This result suggests that no single parameter offers an energetic advantage over the others. Finally, we show that retracting the wing during upstroke reduces power requirements for flapping and increases net lift production, but decreases net thrust production. These results compare well with studies performed on C. brachyotis, offering insight into natural flight kinematics. PMID:24851830

  7. The Effects of Attentional Focusing Instructions on Force Production During the Isometric Midthigh Pull.

    PubMed

    Halperin, Israel; Williams, Kym J; Martin, David T; Chapman, Dale W

    2016-04-01

    Halperin, I, Williams, KJ, Martin, DT, and Chapman, DW. The effects of attentional focusing instructions on force production during the isometric midthigh pull. J Strength Cond Res 30(4): 919-923, 2016-Verbal instructions play a key role in motor learning and performance. Whereas directing one's attention toward bodily movements or muscles (internal focus) tends to hinder performance, instructing persons to focus on the movement outcome, or an external object related to the performed task (external focus) enhances performance. The study's purpose was to examine whether focus of attention affects maximal force production during an isometric midthigh pull (IMTP) among 18 trained athletes (8F & 10M). Athletes performed 3 IMTP trials a day for 3 consecutive days. The first day was a familiarization session in which athlete's received only control instructions. The following 2 days athletes received either control, internal, or external focus of attention instructions in a randomized, within-subject design. Compared to performance with an internal focus of attention, athletes applied 9% greater force when using an external focus of attention (p < 0.001, effect size [ES] = 0.33) and 5% greater force with control instructions (p = 0.001, ES = 0.28). A small positive 3% advantage was observed between performances with an external focus of attention compared with control instructions (p = 0.03, ES = 0.13). Focusing internally on body parts and/or muscle groups during a movement task that requires maximal force hinders performance, whereas focusing on an object external to the self leads to enhanced force production, even when using a simple multijoint static task such as the IMTP. PMID:27003451

  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. Relationship Between Force Production During Isometric Squats and Knee Flexion Angles During Landing.

    PubMed

    Fisher, Harry; Stephenson, Mitchell L; Graves, Kyle K; Hinshaw, Taylour J; Smith, Derek T; Zhu, Qin; Wilson, Margaret A; Dai, Boyi

    2016-06-01

    Fisher, H, Stephenson, ML, Graves, KK, Hinshaw, TJ, Smith, DT, Zhu, Q, Wilson, MA, and Dai, B. Relationship between force production during isometric squats and knee flexion angles during landing. J Strength Cond Res 30(6): 1670-1679, 2016-Decreased knee flexion angles during landing are associated with increased anterior cruciate ligament loading. The underlying mechanisms associated with decreased self-selected knee flexion angles during landing are still unclear. The purpose of this study was to establish the relationship between the peak force production at various knee flexion angles (35, 55, 70, and 90°) during isometric squats and the actual knee flexion angles that occur during landing in both men and women. A total of 18 men and 18 women recreational/collegiate athletes performed 4 isometric squats at various knee flexion angles while vertical ground reaction forces were recorded. Participants also performed a jump-landing-jump task while lower extremity kinematics were collected. For women, significant correlations were found between the peak force production at 55 and 70° of knee flexion during isometric squats and the knee flexion angle at initial contact of landing. There were also significant correlations between the peak force production at 55, 70, and 90° of knee flexion during isometric squats and the peak knee flexion angle during landing. These correlations tended to be stronger during isometric squats at greater knee flexion compared with smaller knee flexion. No significant correlations were found for men. Posture-specific strength may play an important role in determining self-selected knee flexion angles during landing for women. PMID:26566166

  10. 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

  11. Control of cytoplasmic dynein force production and processivity by its C-terminal domain

    NASA Astrophysics Data System (ADS)

    Nicholas, Matthew P.; Höök, Peter; Brenner, Sibylle; Wynne, Caitlin L.; Vallee, Richard B.; Gennerich, Arne

    2015-02-01

    Cytoplasmic dynein is a microtubule motor involved in cargo transport, nuclear migration and cell division. Despite structural conservation of the dynein motor domain from yeast to higher eukaryotes, the extensively studied S. cerevisiae dynein behaves distinctly from mammalian dyneins, which produce far less force and travel over shorter distances. However, isolated reports of yeast-like force production by mammalian dynein have called interspecies differences into question. We report that functional differences between yeast and mammalian dynein are real and attributable to a C-terminal motor element absent in yeast, which resembles a ‘cap’ over the central pore of the mammalian dynein motor domain. Removal of this cap increases the force generation of rat dynein from 1 pN to a yeast-like 6 pN and greatly increases its travel distance. Our findings identify the CT-cap as a novel regulator of dynein function.

  12. 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.

  13. 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

  14. 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

  15. 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

  16. Ongoing characterization of the forced electron beam induced arc discharge ion source for the selective production of exotic species facility

    SciTech Connect

    Manzolaro, M. Andrighetto, A.; Monetti, A.; Scarpa, D.; Rossignoli, M.; Vasquez, J.; Corradetti, S.; Calderolla, M.; Prete, G.; Meneghetti, G.

    2014-02-15

    An intense research and development activity to finalize the design of the target ion source system for the selective production of exotic species (SPES) facility (operating according to the isotope separation on line technique) is at present ongoing at Legnaro National Laboratories. In particular, the characterization of ion sources in terms of ionization efficiency and transversal emittance is currently in progress, and a preliminary set of data is already available. In this work, the off-line ionization efficiency and emittance measurements for the SPES forced electron beam induced arc discharge ion source in the case of a stable Ar beam are presented in detail.

  17. 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

  18. Mouse forepaw lumbrical muscles are resistant to age-related declines in force production.

    PubMed

    Russell, Katelyn A; Ng, Rainer; Faulkner, John A; Claflin, Dennis R; Mendias, Christopher L

    2015-05-01

    A progressive loss of skeletal muscle mass and force generating capacity occurs with aging. Mice are commonly used in the study of aging-associated changes in muscle size and strength, with most models of aging demonstrating 15-35% reductions in muscle mass, cross-sectional area (CSA), maximum isometric force production (Po) and specific force (sPo), which is Po/CSA. The lumbrical muscle of the mouse forepaw is exceptionally small, with corresponding short diffusion distances that make it ideal for in vitro pharmacological studies and measurements of contractile properties. However, the aging-associated changes in lumbrical function have not previously been reported. To address this, we tested the hypothesis that compared to adult (12month old) mice, the forepaw lumbrical muscles of old (30month old) mice exhibit aging-related declines in size and force production similar to those observed in larger limb muscles. We found that the forepaw lumbricals were composed exclusively of fibers with type II myosin heavy chain isoforms, and that the muscles accumulated connective tissue with aging. There were no differences in the number of fibers per whole-muscle cross-section or in muscle fiber CSA. The whole muscle CSA in old mice was increased by 17%, but the total CSA of all muscle fibers in a whole-muscle cross-section was not different. No difference in Po was observed, and while sPo normalized to total muscle CSA was decreased in old mice by 22%, normalizing Po by the total muscle fiber CSA resulted in no difference in sPo. Combined, these results indicate that forepaw lumbrical muscles from 30month old mice are largely protected from the aging-associated declines in size and force production that are typically observed in larger limb muscles. PMID:25762422

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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

  4. Ion drag force on an absorbing grain in highly collisional plasma in the presence of plasma production and loss processes

    SciTech Connect

    Chaudhuri, Manis; Khrapak, Sergei A.; Morfill, Gregor E.

    2008-09-07

    The ion drag force acting on a small absorbing spherical grain has been calculated analytically in highly collisional plasma with slowly drifting ions taking into account plasma production and loss mechanisms in the vicinity of the grain. It is shown that both the magnitude and direction of the ion drag force are strongly influenced by the plasma production and loss mechanisms. The parameter regimes for the 'positive' and 'negative' ion drag forces acting on an absorbing grain have been identified.

  5. Investigating the Force Production of Functionally-Graded Flexible Wings in Flapping Wing Flight

    NASA Astrophysics Data System (ADS)

    Mudbhari, Durlav; Erdogan, Malcolm; He, Kai; Bateman, Daniel; Lipkis, Rory; Moored, Keith

    2015-11-01

    Birds, insects and bats oscillate their wings to propel themselves over long distances and to maneuver with unprecedented agility. A key element to achieve their impressive aerodynamic performance is the flexibility of their wings. Numerous studies have shown that homogeneously flexible wings can enhance force production, propulsive efficiency and lift efficiency. Yet, animal wings are not homogenously flexible, but instead have varying material properties. The aim of this study is to characterize the force production and energetics of functionally-graded flexible wings. A partially-flexible wing composed of a rigid section and a flexible section is used as a first-order model of functionally-graded materials. The flexion occurs in the spanwise direction and it is affected by the spanwise flexion ratio, that is, the ratio of the length of the rigid section compared to the total span length. By varying the flexion ratio as well as the material properties of the flexible section, the study aims to examine the force production and energetics of flapping flight with functionally-graded flexible wings. Supported by the Office of Naval Research under Program Director Dr. Bob Brizzolara, MURI grant number N00014-14-1-0533.

  6. 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

  7. Identification of forced degradation products of tamsulosin using liquid chromatography/electrospray ionization tandem mass spectrometry.

    PubMed

    Namdev, Deepak; Borkar, Roshan M; Raju, B; Kalariya, Pradipbhai D; Rahangdale, Vinodkumar T; Gananadhamu, S; Srinivas, R

    2014-01-01

    A rapid and gradient high-performance liquid chromatography combined with quadrupole time-of-flight electrospray ionization tandem mass spectrometry (LC/Q-TOF-ESI-MS/MS) method has been developed for the identification and structural characterization of stressed degradation products of tamsulosin. Tamsulosin, a selective α1-adrenoceptor antagonist, was subjected to forced degradation studies under hydrolytic (acid, base and neutral), oxidative, photolytic and thermal stress conditions as per ICH guidelines Q1A (R2). The drug degraded significantly under hydrolytic (base and neutral), thermal, oxidative and photolytic conditions, while it was stable to acid hydrolytic stress conditions. A total of twelve degradation products were formed and the chromatographic separation of the drug and its degradation products were achieved on a GRACE C-18 column (250mm×4.6mm, 5μm). All the degradants have been identified and characterized by LC/ESI-MS/MS and accurate mass measurements. To elucidate the structures of degradation products, fragmentation of the [M+H](+) ions of tamsulosin and its degradation products was studied by using LC-MS/MS experiments combined with accurate mass measurements. The product ions of all the protonated degradation products were compared with the product ions of protonated tamsulosin to assign most probable structures for the observed degradation products. PMID:24083958

  8. 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

  9. 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

  10. 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.

  11. 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

  12. TMS reveals a direct influence of spinal projections from human SMAp on precise force production.

    PubMed

    Entakli, Jonathan; Bonnard, Mireille; Chen, Sophie; Berton, Eric; De Graaf, Jozina B

    2014-01-01

    The corticospinal (CS) system plays an important role in fine motor control, especially in precision grip tasks. Although the primary motor cortex (M1) is the main source of the CS projections, other projections have been found, especially from the supplementary motor area proper (SMAp). To study the characteristics of these CS projections from SMAp, we compared muscle responses of an intrinsic hand muscle (FDI) evoked by stimulation of human M1 and SMAp during an isometric static low-force control task. Subjects were instructed to maintain a small cursor on a target force curve by applying a pressure with their right precision grip on a force sensor. Neuronavigated transcranial magnetic stimulation was used to stimulate either left M1 or left SMAp with equal induced electric field values at the defined cortical targets. The results show that the SMAp stimulation evokes reproducible muscle responses with similar latencies and amplitudes as M1 stimulation, and with a clear and significant shorter silent period. These results suggest that (i) CS projections from human SMAp are as rapid and efficient as those from M1, (ii) CS projections from SMAp are directly involved in control of the excitability of spinal motoneurons and (iii) SMAp has a different intracortical inhibitory circuitry. We conclude that human SMAp and M1 both have direct influence on force production during fine manual motor tasks. PMID:24164635

  13. Impact of Short-Range Forces on Defect Production from High-Energy Collisions

    DOE PAGESBeta

    Stoller, R. E.; Tamm, A.; Béland, L. K.; Samolyuk, G. D.; Stocks, G. M.; Caro, A.; Slipchenko, L. V.; Osetsky, Yu. N.; Aabloo, A.; Klintenberg, M.; et al

    2016-04-25

    Primary radiation damage formation in solid materials typically involves collisions between atoms that have up to a few hundred keV of kinetic energy. The distance between two colliding atoms can approach 0.05 nm during these collisions. At such small atomic separations, force fields fitted to equilibrium properties tend to significantly underestimate the potential energy of the colliding dimer. To enable molecular dynamics simulations of high-energy collisions, it is common practice to use a screened Coulomb force field to describe the interactions and to smoothly join this to the equilibrium force field at a suitable interatomic spacing. But, there is nomore » accepted standard method for choosing the parameters used in the joining process, and our results prove that defect production is sensitive to how the force fields are linked. A new procedure is presented that involves the use of ab initio calculations to determine the magnitude and spatial dependence of the pair interactions at intermediate distances, along with systematic criteria for choosing the joining parameters. Results are presented for the case of nickel, which demonstrate the use and validity of the procedure.« less

  14. Impact of Short-Range Forces on Defect Production from High-Energy Collisions.

    PubMed

    Stoller, R E; Tamm, A; Béland, L K; Samolyuk, G D; Stocks, G M; Caro, A; Slipchenko, L V; Osetsky, Yu N; Aabloo, A; Klintenberg, M; Wang, Y

    2016-06-14

    Primary radiation damage formation in solid materials typically involves collisions between atoms that have up to a few hundred keV of kinetic energy. During these collisions, the distance between two colliding atoms can approach 0.05 nm. At such small atomic separations, force fields fitted to equilibrium properties tend to significantly underestimate the potential energy of the colliding dimer. To enable molecular dynamics simulations of high-energy collisions, it is common practice to use a screened Coulomb force field to describe the interactions and to smoothly join this to the equilibrium force field at a suitable interatomic spacing. However, there is no accepted standard method for choosing the parameters used in the joining process, and our results prove that defect production is sensitive to how the force fields are linked. A new procedure is presented that involves the use of ab initio calculations to determine the magnitude and spatial dependence of the pair interactions at intermediate distances, along with systematic criteria for choosing the joining parameters. Results are presented for the case of nickel, which demonstrate the use and validity of the procedure. PMID:27110927

  15. Ion drag force on a small grain in highly collisional weakly anisotropic plasma: Effect of plasma production and loss mechanisms

    SciTech Connect

    Chaudhuri, M.; Khrapak, S. A.; Morfill, G. E.

    2008-05-15

    The ion drag force acting on a small absorbing grain has been calculated in highly collisional plasma with slowly drifting ions taking into account plasma production and loss processes in the vicinity of the grain. It is shown that the strength of the plasma production and loss mechanisms not only affects the magnitude of the ion drag force, but also determines the direction of the force. The parameter regimes for the ''positive'' and ''negative'' ion drag forces have been identified. In addition, the qualitative features of the electric potential distribution around the grain in isotropic conditions (in the absence of the ion drift) are investigated.

  16. 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

  17. Unconventional entropy production in the presence of momentum-dependent forces

    NASA Astrophysics Data System (ADS)

    Kwon, Chulan; Yeo, Joonhyun; Lee, Hyun Keun; Park, Hyunggyu

    2016-03-01

    We investigate the unconventional nature of entropy production (EP) in nonequilibrium systems with odd-parity variables that change signs under time reversal. We consider the Brownian motion of a particle in contact with a heat reservoir, where the particle's momentum is an odd-parity variable. In the presence of an external momentum-dependent force, the EP transferred to the environment is found to be not equivalent to the usual reservoir entropy change due to heat transfer. An additional unconventional contribution to the EP, which is crucial for maintaining the non-negativity of the (average) total EP enforced by the second law of thermodynamics, appears. A few examples are considered to elucidate the novel nature of the EP. We also discuss detailed balance conditions with a momentum-dependent force.

  18. 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

  19. Sum Product Networks for Activity Recognition.

    PubMed

    Amer, Mohamed R; Todorovic, Sinisa

    2016-04-01

    This paper addresses detection and localization of human activities in videos. We focus on activities that may have variable spatiotemporal arrangements of parts, and numbers of actors. Such activities are represented by a sum-product network (SPN). A product node in SPN represents a particular arrangement of parts, and a sum node represents alternative arrangements. The sums and products are hierarchically organized, and grounded onto space-time windows covering the video. The windows provide evidence about the activity classes based on the Counting Grid (CG) model of visual words. This evidence is propagated bottom-up and top-down to parse the SPN graph for the explanation of the video. The node connectivity and model parameters of SPN and CG are jointly learned under two settings, weakly supervised, and supervised. For evaluation, we use our new Volleyball dataset, along with the benchmark datasets VIRAT, UT-Interactions, KTH, and TRECVID MED 2011. Our video classification and activity localization are superior to those of the state of the art on these datasets. PMID:26390445

  20. 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.

  1. 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.

  2. Enhanced production of 2,3-butanediol from glycerol by forced pH fluctuations.

    PubMed

    Petrov, Kaloyan; Petrova, Penka

    2010-07-01

    The glycerol fermentation by Klebsiella pneumoniae occurs by receiving more than five liquid products-organic acids, diols, and ethanol. Aiming to direct the glycerol conversion towards predominant production of 2,3-butanediol (2,3-BD), the main influencing parameters (the aeration and the pH) were investigated during fed-batch processes. The regime of intensive aeration (2.2 vvm air supply) was evaluated as most favorable for 2,3-BD synthesis and ensured the decrease of all other metabolites. Thus, without pH control, 52.5 g/l 2,3-BD were produced, as the carbon conversion of glycerol into 2,3-BD reached 60.6%. Additional enhancement in 2,3-BD production (by significant increase of glycerol utilization) was achieved by the development of a new method of "forced pH fluctuations". It was realized by consecutive raisings of pH using definite DeltapH value, at exact time intervals, allowing multiple variations. Thus, the optimal conditions for maximal glycerol consumption were defined, and 70 g/l 2,3-BD were produced, which is the highest amount obtained from glycerol as a sole carbon source until now. The forced pH fluctuations emphasized pH as a governing factor in microbial conversion processes. PMID:20361325

  3. Realistic prediction of solid pharmaceutical oxidation products by using a novel forced oxidation system.

    PubMed

    Ueyama, Eiji; Tamura, Kousuke; Mizukawa, Kousei; Kano, Kenji

    2014-04-01

    This study investigated a novel solid-state-based forced oxidation system to enable a realistic prediction of pharmaceutical product oxidation, a key consideration in drug development and manufacture. Polysorbate 80 and ferric(III) acetylacetonate were used as an organic hydroperoxide source and a transition metal catalyst, respectively. Homogeneous solutions of target compounds and these reagents were prepared in a mixed organic solvent. The organic solvent was removed rapidly under reduced pressure, and the oxidation of the resulting dried solid was investigated. Analysis of the oxidation products generated in test compounds by this proposed forced oxidation system using HPLC showed a high similarity with those generated during more prolonged naturalistic drug oxidation. The proposed system provided a better predictive performance in prediction of realistic oxidative degradants of the drugs tested than did other established methods. Another advantage of this system was that the generation of undesired products of hydrolysis, solvolysis, and thermolysis was prevented because efficient oxidation was achieved under mild conditions. The results of this study suggest that this system is suitable for a realistic prediction of oxidative degradation of solid pharmaceuticals. PMID:24497072

  4. 75 FR 8402 - Child Labor, Forced Labor, and Forced or Indentured Child Labor in the Production of Goods in...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-24

    ... believe might have been mined, produced or manufactured with forced or indentured child labor (66 FR 5353... goods (72 FR 73374). The guidelines set forth the criteria by which information is evaluated... appropriate, revising the List (66 FR 5351). Based on DOL research and information submitted by the...

  5. 77 FR 70473 - Child Labor, Forced Labor, and Forced or Indentured Child Labor in the Production of Goods in...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-26

    ... that ILAB follows in developing the TVPRA List (72 FR 73374). The guidelines set forth the criteria by... forced or indentured child labor (66 FR 5353). In addition to the List, the Department also published on..., and, as appropriate, revising the EO List (66 FR 5351). Pursuant to Sections D through G of...

  6. 76 FR 22921 - Child Labor, Forced Labor, and Forced or Indentured Child Labor in the Production of Goods in...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-25

    ... goods (72 FR 73374). The guidelines set forth the criteria by which information is evaluated... manufactured with forced or indentured child labor (66 FR 5353). In addition to the List, the Department also..., reviewing, and, as appropriate, revising the List (66 FR 5351). Based on DOL research and...

  7. 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.

  8. 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

  9. Activation product transport in fusion reactors. [RAPTOR

    SciTech Connect

    Klein, A.C.

    1983-01-01

    Activated corrosion and neutron sputtering products will enter the coolant and/or tritium breeding material of fusion reactor power plants and experiments and cause personnel access problems. Radiation levels around plant components due to these products will cause difficulties with maintenance and repair operations throughout the plant. Similar problems are experienced around fission reactor systems. The determination of the transport of radioactive corrosion and neutron sputtering products through the system is achieved using the computer code RAPTOR. This code calculates the mass transfer of a number of activation products based on the corrosion and sputtering rates through the system, the deposition and release characteristics of various plant components, the neturon flux spectrum, as well as other plant parameters. RAPTOR assembles a system of first order linear differential equations into a matrix equation based upon the reactor system parameters. Included in the transfer matrix are the deposition and erosion coefficients, and the decay and activation data for the various plant nodes and radioactive isotopes. A source vector supplies the corrosion and neutron sputtering source rates. This matrix equation is then solved using a matrix operator technique to give the specific activity distribution of each radioactive species throughout the plant. Once the amount of mass transfer is determined, the photon transport due to the radioactive corrosion and sputtering product sources can be evaluated, and dose rates around the plant components of interest as a function of time can be determined. This method has been used to estimate the radiation hazards around a number of fusion reactor system designs.

  10. Chronic clenbuterol treatment compromises force production without directly altering skeletal muscle contractile machinery.

    PubMed

    Py, G; Ramonatxo, C; Sirvent, P; Sanchez, A M J; Philippe, A G; Douillard, A; Galbès, O; Lionne, C; Bonnieu, A; Chopard, A; Cazorla, O; Lacampagne, A; Candau, R B

    2015-04-15

    Clenbuterol is a β2 -adrenergic receptor agonist known to induce skeletal muscle hypertrophy and a slow-to-fast phenotypic shift. The aim of the present study was to test the effects of chronic clenbuterol treatment on contractile efficiency and explore the underlying mechanisms, i.e. the muscle contractile machinery and calcium-handling ability. Forty-three 6-week-old male Wistar rats were randomly allocated to one of six groups that were treated with either subcutaneous equimolar doses of clenbuterol (4 mg kg(-1) day(-1) ) or saline solution for 9, 14 or 21 days. In addition to the muscle hypertrophy, although an 89% increase in absolute maximal tetanic force (Po ) was noted, specific maximal tetanic force (sPo) was unchanged or even depressed in the slow twitch muscle of the clenbuterol-treated rats (P < 0.05). The fit of muscle contraction and relaxation force kinetics indicated that clenbuterol treatment significantly reduced the rate constant of force development and the slow and fast rate constants of relaxation in extensor digitorum longus muscle (P < 0.05), and only the fast rate constant of relaxation in soleus muscle (P < 0.05). Myofibrillar ATPase activity increased in both relaxed and activated conditions in soleus (P < 0.001), suggesting that the depressed specific tension was not due to the myosin head alteration itself. Moreover, action potential-elicited Ca(2+) transients in flexor digitorum brevis fibres (fast twitch fibres) from clenbuterol-treated animals demonstrated decreased amplitude after 14 days (-19%, P < 0.01) and 21 days (-25%, P < 0.01). In conclusion, we showed that chronic clenbuterol treatment reduces contractile efficiency, with altered contraction and relaxation kinetics, but without directly altering the contractile machinery. Lower Ca(2+) release during contraction could partially explain these deleterious effects. PMID:25656230

  11. Chronic clenbuterol treatment compromises force production without directly altering skeletal muscle contractile machinery

    PubMed Central

    Py, G; Ramonatxo, C; Sirvent, P; Sanchez, A M J; Philippe, A G; Douillard, A; Galbès, O; Lionne, C; Bonnieu, A; Chopard, A; Cazorla, O; Lacampagne, A; Candau, R B

    2015-01-01

    Clenbuterol is a β2-adrenergic receptor agonist known to induce skeletal muscle hypertrophy and a slow-to-fast phenotypic shift. The aim of the present study was to test the effects of chronic clenbuterol treatment on contractile efficiency and explore the underlying mechanisms, i.e. the muscle contractile machinery and calcium-handling ability. Forty-three 6-week-old male Wistar rats were randomly allocated to one of six groups that were treated with either subcutaneous equimolar doses of clenbuterol (4 mg kg−1 day−1) or saline solution for 9, 14 or 21 days. In addition to the muscle hypertrophy, although an 89% increase in absolute maximal tetanic force (Po) was noted, specific maximal tetanic force (sPo) was unchanged or even depressed in the slow twitch muscle of the clenbuterol-treated rats (P < 0.05). The fit of muscle contraction and relaxation force kinetics indicated that clenbuterol treatment significantly reduced the rate constant of force development and the slow and fast rate constants of relaxation in extensor digitorum longus muscle (P < 0.05), and only the fast rate constant of relaxation in soleus muscle (P < 0.05). Myofibrillar ATPase activity increased in both relaxed and activated conditions in soleus (P < 0.001), suggesting that the depressed specific tension was not due to the myosin head alteration itself. Moreover, action potential-elicited Ca2+ transients in flexor digitorum brevis fibres (fast twitch fibres) from clenbuterol-treated animals demonstrated decreased amplitude after 14 days (−19%, P < 0.01) and 21 days (−25%, P < 0.01). In conclusion, we showed that chronic clenbuterol treatment reduces contractile efficiency, with altered contraction and relaxation kinetics, but without directly altering the contractile machinery. Lower Ca2+ release during contraction could partially explain these deleterious effects. PMID:25656230

  12. Production Of High Specific Activity Copper-67

    DOEpatents

    Jamriska, Sr., David J.; Taylor, Wayne A.; Ott, Martin A.; Fowler, Malcolm; Heaton, Richard C.

    2003-10-28

    A process for the selective production and isolation of high specific activity Cu.sup.67 from proton-irradiated enriched Zn.sup.70 target comprises target fabrication, target irradiation with low energy (<25 MeV) protons, chemical separation of the Cu.sup.67 product from the target material and radioactive impurities of gallium, cobalt, iron, and stable aluminum via electrochemical methods or ion exchange using both anion and cation organic ion exchangers, chemical recovery of the enriched Zn.sup.70 target material, and fabrication of new targets for re-irradiation is disclosed.

  13. Production Of High Specific Activity Copper-67

    DOEpatents

    Jamriska, Sr., David J.; Taylor, Wayne A.; Ott, Martin A.; Fowler, Malcolm; Heaton, Richard C.

    2002-12-03

    A process for the selective production and isolation of high specific activity cu.sup.67 from proton-irradiated enriched Zn.sup.70 target comprises target fabrication, target irradiation with low energy (<25 MeV) protons, chemical separation of the Cu.sup.67 product from the target material and radioactive impurities of gallium, cobalt, iron, and stable aluminum via electrochemical methods or ion exchange using both anion and cation organic ion exchangers, chemical recovery of the enriched Zn.sup.70 target material, and fabrication of new targets for re-irradiation is disclosed.

  14. Vortexlet models of flapping flexible wings show tuning for force production and control.

    PubMed

    Mountcastle, A M; Daniel, T L

    2010-12-01

    Insect wings are compliant structures that experience deformations during flight. Such deformations have recently been shown to substantially affect induced flows, with appreciable consequences to flight forces. However, there are open questions related to the aerodynamic mechanisms underlying the performance benefits of wing deformation, as well as the extent to which such deformations are determined by the boundary conditions governing wing actuation together with mechanical properties of the wing itself. Here we explore aerodynamic performance parameters of compliant wings under periodic oscillations, subject to changes in phase between wing elevation and pitch, and magnitude and spatial pattern of wing flexural stiffness. We use a combination of computational structural mechanics models and a 2D computational fluid dynamics approach to ask how aerodynamic force production and control potential are affected by pitch/elevation phase and variations in wing flexural stiffness. Our results show that lift and thrust forces are highly sensitive to flexural stiffness distributions, with performance optima that lie in different phase regions. These results suggest a control strategy for both flying animals and engineering applications of micro-air vehicles. PMID:21098955

  15. Force-production asymmetry in male and female athletes of differing strength levels.

    PubMed

    Bailey, Christopher A; Sato, Kimitake; Burnett, Angus; Stone, Michael H

    2015-05-01

    The purpose of this investigation was to determine the existence of bilateral strength and force-production asymmetry and evaluate possible differences based on sex, as well as strength level. Asymmetry was assessed during weight-distribution (WtD) testing, unloaded and lightly loaded static- (SJ) and countermovement-jump (CMJ) testing, and isometric midthigh-pull (IMTP) strength testing. Subjects included 63 athletes (31 male, 32 female) for WtD, SJ, and CMJ tests, while 129 athletes (64 male, 65 female) participated in IMTP testing. Independent-samples t tests were used to determine possible differences in asymmetry magnitude between males and females, as well as between strong and weak athletes. Cohen d effect-size (ES) estimates were also used to estimate difference magnitudes. Statistically different asymmetry levels with moderate to strong ESs were seen between males and females in WtD, 0-kg SJ (peak force [PF]), 20-kg SJ (peak power [PP]), 0-kg CMJ (PF, PP, net impulse), and 20-kg CMJ (PF), but no statistical differences were observed in IMTP variables. Dividing the sample into strong and weak groups produced statistically significant differences with strong ES estimates in IMTP PF and rate of force development, and many ESs in jump symmetry variables increased. The results of this investigation indicate that females may be more prone to producing forces asymmetrically than males during WtD and jumping tasks. Similarly, weaker athletes displayed more asymmetry than stronger athletes. This may indicate that absolute strength may play a larger role in influencing asymmetry magnitude than sex. PMID:25394294

  16. Muscle force production during bent-knee, bent-hip walking in humans.

    PubMed

    Foster, Adam D; Raichlen, David A; Pontzer, Herman

    2013-09-01

    Researchers have long debated the locomotor posture used by the earliest bipeds. While many agree that by 3-4 Ma (millions of years ago), hominins walked with an extended-limb human style of bipedalism, researchers are still divided over whether the earliest bipeds walked like modern humans, or walked with a more bent-knee, bent-hip (BKBH) ape-like form of locomotion. Since more flexed postures are associated with higher energy costs, reconstructing early bipedal mechanics has implications for the selection pressures that led to upright walking. The purpose of this study is to determine how modern human anatomy functions in BKBH walking to clarify the links between morphology and energy costs in different mechanical regimes. Using inverse dynamics, we calculated muscle force production at the major limb joints in humans walking in two modes, both with extended limbs and BKBH. We found that in BKBH walking, humans must produce large muscle forces at the knee to support body weight, leading to higher estimated energy costs. However, muscle forces at the hip remained similar in BKBH and extended limb walking, suggesting that anatomical adaptations for hip extension in humans do not necessarily diminish the effective mechanical advantage at the hip in more flexed postures. We conclude that the key adaptations for economical walking, regardless of joint posture, seem to center on maintaining low muscle forces at the hip, primarily by keeping low external moments at the hip. We explore the implications of these results for interpreting locomotor energetics in early hominins, including australopithecines and Ardipithecus ramidus. PMID:23928351

  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.

    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.

  18. 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

  19. 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

  20. 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.

  1. 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

  2. Current natural products with antihypertensive activity.

    PubMed

    Bai, Ren-Ren; Wu, Xiao-Ming; Xu, Jin-Yi

    2015-10-01

    Natural products have been an important source of new drugs, which also played a dominant role in the discovery and research of new drugs for the treatment of hypertension. This review article reviews the recent progress in the research and development of natural lead compounds with antihypertensive activity, including alkaloids, diterpenes, coumarins, flavonoids, and peptides. We summarized their structures, sources, as well as the antihypertensive mechanisms. These information provides instructive reference for the following structural modifications and optimization. PMID:26481372

  3. 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…

  4. 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

  5. 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…

  6. Design for manufacturability production management activity report

    NASA Astrophysics Data System (ADS)

    Miyazaki, Norihiko; Sato, T.; Honma, M.; Yoshioka, N.; Hosono, K.; Onodera, T.; Itoh, H.; Suzuki, H.; Uga, T.; Kadota, K.; Iriki, N.

    2006-05-01

    Design For Manufacturability Production Management (DFM-PM) Subcommittee has been started in succession to Reticle Management Subcommittee (RMS) in Semiconductor Manufacturing Technology Committee for Japan (SMTCJ) from 2005. Our activity focuses on the SoC (System On Chip) Business, and it pursues the improvement of communication in manufacturing technique. The first theme of activity is the investigation and examination of the new trends about production (manufacturer) technology and related information, and proposals of business solution. The second theme is the standardization activity about manufacture technology and the cooperation with related semiconductors' organizations. And the third theme is holding workshop and support for promotion and spread of the standardization technology throughout semiconductor companies. We expand a range of scope from design technology to wafer pattern reliability and we will propose the competition domain, the collaboration area and the standardization technology on DFM. Furthermore, we will be able to make up a SoC business model as the 45nm node technology beyond manufacturing platform in cooperating with the design information and the production information by utilizing EDA technology.

  7. 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.

  8. Lift vs. drag based mechanisms for vertical force production in the smallest flying insects.

    PubMed

    Jones, S K; Laurenza, R; Hedrick, T L; Griffith, B E; Miller, L A

    2015-11-01

    We used computational fluid dynamics to determine whether lift- or drag-based mechanisms generate the most vertical force in the flight of the smallest insects. These insects fly at Re on the order of 4-60 where viscous effects are significant. Detailed quantitative data on the wing kinematics of the smallest insects is not available, and as a result both drag- and lift-based strategies have been suggested as the mechanisms by which these insects stay aloft. We used the immersed boundary method to solve the fully-coupled fluid-structure interaction problem of a flexible wing immersed in a two-dimensional viscous fluid to compare three idealized hovering kinematics: a drag-based stroke in the vertical plane, a lift-based stroke in the horizontal plane, and a hybrid stroke on a tilted plane. Our results suggest that at higher Re, a lift-based strategy produces more vertical force than a drag-based strategy. At the Re pertinent to small insect hovering, however, there is little difference in performance between the two strategies. A drag-based mechanism of flight could produce more vertical force than a lift-based mechanism for insects at Re<5; however, we are unaware of active fliers at this scale. PMID:26300066

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. Regulating emotions uniquely modifies reaction time, rate of force production, and accuracy of a goal-directed motor action.

    PubMed

    Beatty, Garrett F; Fawver, Bradley; Hancock, Gabriella M; Janelle, Christopher M

    2014-02-01

    We investigated how emotion regulation (ER) strategies influence the execution of a memory guided, ballistic pinch grip. Participants (N=33) employed ER strategies (expressive suppression, emotional expression, and attentional deployment) while viewing emotional stimuli (IAPS images). Upon stimulus offset, participants produced a targeted pinch force aimed at 10% of their maximum voluntary contraction. Performance measures included reaction time (RT), rate of force production, and performance accuracy. As hypothesized, attentional deployment resulted in the slowest RT, largest rate of force production, and poorest performance accuracy. In contrast, expressive suppression reduced the rate of force production and increased performance accuracy relative to emotional expression and attentional deployment. Findings provide evidence that emotion regulation strategies uniquely influence human movement. Future work should further delineate the interacting role that emotion regulation strategies have in modulating both affective experience and motor performance. PMID:24576703

  17. 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.

  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. 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.

  20. 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

  1. 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

  2. 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.

  3. 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

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

    PubMed

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

    2015-12-01

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

  5. 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.

  6. 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

  7. 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

  8. Muscle-tendon unit stiffness does not independently affect voluntary explosive force production or muscle intrinsic contractile properties.

    PubMed

    Hannah, Ricci; Folland, Jonathan P

    2015-01-01

    This study examined the relationship of muscle-tendon unit (MTU) stiffness and explosive force production during voluntary and evoked contractions of the knee extensors. Thirty-four untrained participants performed a series of explosive voluntary and electrically evoked (octets (8 pulses, 300 Hz) via femoral nerve stimulation) isometric contractions. Maximum voluntary force (MVF) was assessed during maximum voluntary contractions. Explosive force production was assessed as the time taken, from force onset (0 N), to achieve specific levels of absolute (25-300 N) and relative force (5%-75% MVF) during the explosive contractions. Ultrasonic images of the vastus lateralis were recorded during 10-s ramp contractions to assess MTU stiffness, which was expressed in absolute (N · mm(-1)) and relative (to MVF and resting tendon-aponeurosis length) terms. Bivariate correlations suggested that absolute MTU stiffness was associated with voluntary explosive force (time to achieve 150-300 N: r = -0.35 to -0.54, P < 0.05). However, no relationships between stiffness and voluntary explosive force were observed when the influence of MVF was removed, either via partial correlations of absolute values (P ≥ 0.49) or considering relative values (P ≥ 0.14). Similarly, absolute MTU stiffness was related to explosive force during evoked octet contractions (r = -0.41 to -0.64, P < 0.05), but these correlations were no longer present when accounting for the influence of MVF (P ≥ 0.15). Therefore, once maximum strength was considered, MTU stiffness had no independent relationship with voluntary explosive force production or the evoked capacity for explosive force. PMID:25494973

  9. Production of high specific activity silicon-32

    SciTech Connect

    Phillips, D.R.; Brzezinski, M.A.

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development Project (LDRD) at Los Alamos National Laboratory (LANL). There were two primary objectives for the work performed under this project. The first was to take advantage of capabilities and facilities at Los Alamos to produce the radionuclide {sup 32}Si in unusually high specific activity. The second was to combine the radioanalytical expertise at Los Alamos with the expertise at the University of California to develop methods for the application of {sup 32}Si in biological oceanographic research related to global climate modeling. The first objective was met by developing targetry for proton spallation production of {sup 32}Si in KCl targets and chemistry for its recovery in very high specific activity. The second objective was met by developing a validated field-useable, radioanalytical technique, based upon gas-flow proportional counting, to measure the dynamics of silicon uptake by naturally occurring diatoms.

  10. 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

  11. 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).

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. Climate forcing, primary production and the distribution of Holocene biogenic sediments in the Gulf of California

    NASA Astrophysics Data System (ADS)

    Douglas, Robert; Gonzalez-Yajimovich, Oscar; Ledesma-Vazquez, Jorge; Staines-Urias, Francisca

    2007-01-01

    The Gulf of California is a marginal seaway under the influence of a monsoon climate that produces cool, dry winters and warm, humid summers. Winds, tidal mixing and coastal-trapped waves forced by climate and the Pacific Ocean control nutrient advection and primary productivity (PP). Strong northwest winds from the subtropical East Pacific High Pressure system begin in November and last until April and drive coastal upwelling along the mainland margin, especially in the central and southern Gulf. In the northern Gulf, particularly around the midrift island, tidal mixing and turbulence occurs year round, advecting nutrients into the mixed layer and high productivity. During summer and early fall months, winds are variable, of less intensity and mainly blow cross-basin except in the most northern Gulf. Summer PP is generally low in the central and southern Gulf except along the mainland where coastal-trapped waves associated with tropical surges and hurricanes generate mixing over the continental shelf. Mesoscale eddies or gyres often associated with jets and filaments extend to depths of 1000 m and transport nutrient-enriched upwelled waters and plankton detritus across the Gulf. The largest and most persistent gyres rotate in an anti-cyclonic direction (east to west) and are a principal source of the plankton export to the peninsula margin. Two major biogenic sediment patterns are present in core-top sediments. Hemipelagic biosiliceous-rich muds are accumulating beneath upwelling areas of high productivity in the central Gulf and along the mainland margin. Calcium carbonate- and organic carbon-rich (OC) sediments are concentrated along the peninsula margin, generally beneath lower productivity waters with the highest OC content in areas with the lowest productivity. The high, uniform biosiliceous content in Guaymas basin, extending southward into Carmen basin reflects the redistribution by mesoscale gyres of phytoplankon debris produced in mainland coastal

  17. 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

  18. 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

  19. Climatic and oceanic forcing of new, net, and diatom production in the North Water

    NASA Astrophysics Data System (ADS)

    Tremblay, Jean-Eric; Gratton, Yves; Fauchot, Juliette; Price, Neil M.

    New, net, and diatom production in the North Water were estimated during May to July 1998 from in vitro measurements of nitrate uptake and mesoscale temporal changes in the inventories of nitrate, silicate, oxygen, and inorganic carbon (DIC). Sampling stations were divided into two domains according to the position of the dominant water types: the silicate-rich Arctic water (SRAW) and Baffin Bay Water (BBW). BBW dominated in the southeast and was associated with relatively shallow upper mixed layers (UMLs) and weak horizontal advection. A phytoplankton bloom started in late April in BBW and grew slowly over 7 weeks, during which time the build-up of particulate organic nitrogen and carbon accounted for ca. 80% of the nitrate and DIC deficit, respectively. Over half of the new production (1.37 g C m -2 d -1) during this period was attributed to wind-driven replenishment of nitrate in the euphotic zone. The bloom culminated when seasonally declining winds and rising temperatures severed the UML from the deep nutrient reservoir. The same change in weather induced ice melt, stratification, and bloom development in northern SRAW, which had previously been characterized by deep UMLs. Collectively, the results imply that the timing and magnitude of blooms in the North Water are controlled by a succession of oceanic and climatic forcings. New C production in the North Water during April to July (1.11 g C m -2 d -1) was an order of magnitude higher than in adjacent waters and up to 8 times higher than in the Northeast Water polynya. As much as 80% of this production was mediated by diatoms >5 μm, suggesting potentially high and efficient C transfer to the herbivorous food web and deep waters.

  20. 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

  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. 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

  3. 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.

  4. 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

  5. Effect of forced aeration on citric acid production by Aspergillus sp. mutants in SSF.

    PubMed

    Rodrigues, Cristine; Vandenberghe, Luciana P S; Sturm, Wilerson; Dergint, Dario E A; Spier, Michele Rigon; de Carvalho, Júlio Cesar; Soccol, Carlos R

    2013-12-01

    Citric acid (CA) is one of the most important products of fermentation in the world. A great variety of agro-industrial residues can be used in solid state fermentation. Aspergillus niger parental strain (CCT 7716) and two strains obtained by mutagenesis (CCT 7717 and CCT 7718) were evaluated in Erlenmeyer flasks and glass columns using citric pulp (CP) as substrate/support, sugarcane molasses and methanol. Best results using glass columns (forced aeration) were found in the fourth day of fermentation: 278.4, 294.9 and 261.1 g CA/kg of dry CP with CCT 7716, CCT 7718 and CCT 7717, respectively. In Erlenmeyer flasks (aeration by diffusion) CA reached 410.7, 446.8 and 492.7 g CA/kg of dry CP with CCT 7716, CCT 7718 and CCT 7717, respectively. The aeration by diffusion improved CA production by the three strains. A data acquisition system specially developed for biotechnological processes analysis was used to perform the respirometric parameters measurement. PMID:23760557

  6. 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

  7. 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

  8. 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

  9. The role of degradant profiling in active pharmaceutical ingredients and drug products.

    PubMed

    Alsante, Karen M; Ando, Akemi; Brown, Roland; Ensing, Janice; Hatajik, Todd D; Kong, Wei; Tsuda, Yoshiko

    2007-01-10

    Forced degradation studies are used to facilitate the development of analytical methodology, to gain a better understanding of active pharmaceutical ingredient (API) and drug product (DP) stability, and to provide information about degradation pathways and degradation products. In order to fulfill development and regulatory needs, this publication provides a roadmap for when and how to perform studies, helpful tools in designing rugged scientific studies, and guidance on how to record and communicate results. PMID:17187892

  10. The effect of metabolic fuel on force production and resting inorganic phosphate levels in mouse skeletal muscle.

    PubMed Central

    Phillips, S K; Wiseman, R W; Woledge, R C; Kushmerick, M J

    1993-01-01

    1. The effect of different metabolic fuels (glucose, pyruvate and lactate) and no exogenous metabolic fuel on force production was studied in isolated mouse soleus and extensor digitorum longus (EDL) muscles. Force was measured, at 25 degrees C, during isometric tetanic contractions and during contractions with isovelocity stretching and shortening. In parallel experiments, measurements were made of the resting phosphorus metabolite levels using 31P NMR. 2. In soleus muscles, the isometric tetanic force was potentiated with pyruvate (20 mM) as metabolic fuel, compared with glucose (11 mM), by 17.8 +/- 3.6% (mean +/- S.E.M., n = 6). The force was the same with no exogenous metabolic fuel, with glucose, or with lactate as metabolic fuel. The force exerted during shortening was also potentiated by pyruvate and by the same proportion as isometric force. However, during rapid stretching there was no force enhancement with pyruvate. The changes in the force seen with pyruvate are qualitatively similar to those produced when inorganic phosphate (Pi) is lowered in skinned rabbit psoas muscle fibres. 3. We tested whether the Pi content decreased in the presence of pyruvate by measuring resting Pi using 31P NMR spectroscopy. We found that, in soleus muscles, resting Pi was present with glucose and absent with pyruvate as metabolic fuel, and the effect was reversible. 4. EDL muscles produced the same isometric force whether the metabolic fuel was glucose, pyruvate, lactate or if no exogenous metabolic fuel was supplied. EDL muscles already had Pi levels below detectability at rest in glucose. There were no changes in the 31P NMR spectrum with pyruvate as metabolic fuel. 5. It appears therefore that the force potentiation in soleus muscles with pyruvate is due to a lowering of Pi. EDL muscles, which have a very low resting Pi in glucose, therefore have very little potential for force enhancement by this mechanism. PMID:8331580

  11. Attenuated rapid onset vasodilation with greater force production in skeletal muscle of caveolin-2-/- mice.

    PubMed

    Fernando, Charmain A; Liu, Yajun; Sowa, Grzegorz; Segal, Steven S

    2016-08-01

    Caveolin-2 (Cav2) is a major protein component of caveolae in membranes of vascular smooth muscle and endothelium, yet its absence alters the ultrastructure of skeletal muscle fibers. To gain insight into Cav2 function in skeletal muscle, we tested the hypothesis that genetic deletion of Cav2 would alter microvascular reactivity and depress contractile function of skeletal muscle in vivo. In the left gluteus maximus muscle (GM) of anesthetized Cav2(-/-) and wild-type (WT) male mice (age, 6 mo), microvascular responses to physiological agonists and to GM contractions were studied at 34°C. For feed arteries (FA), first- (1A), second- (2A) and third-order (3A) arterioles, respective mean diameters at rest (45, 35, 25, 12 μm) and during maximal dilation (65, 55, 45, 30 μm) were similar between groups. Cumulative dilations to ACh (10(-9) to 10(-5) M) and constrictions to norepinephrine (10(-9) to 10(-5) M) were also similar between groups, as were steady-state dilations during rhythmic twitch contractions (2 and 4 Hz; 30 s). For single tetanic contractions (100 Hz; 100, 250, and 500 ms), rapid onset vasodilation (ROV) increased with contraction duration throughout networks in GM of both groups but was reduced by nearly half in Cav2(-/-) mice compared with WT mice (P < 0.05). Nevertheless, maximal force during tetanic contraction was ∼40% greater in GM of Cav2(-/-) vs. WT mice (152 ± 14 vs. 110 ± 3 mN per square millimeter, respectively; P < 0.05). Thus, while structural and functional properties of resistance networks are well maintained in the GM of Cav2(-/-) mice, diminished ROV with greater force production reveals novel physiological roles for Cav2 in skeletal muscle. PMID:27317631

  12. Sphingomyelinase promotes oxidant production and skeletal muscle contractile dysfunction through activation of NADPH oxidase

    PubMed Central

    Loehr, James A.; Abo-Zahrah, Reem; Pal, Rituraj; Rodney, George G.

    2015-01-01

    Elevated concentrations of sphingomyelinase (SMase) have been detected in a variety of diseases. SMase has been shown to increase muscle derived oxidants and decrease skeletal muscle force; however, the sub-cellular site of oxidant production has not been elucidated. Using redox sensitive biosensors targeted to the mitochondria and NADPH oxidase (Nox2), we demonstrate that SMase increased Nox2-dependent ROS and had no effect on mitochondrial ROS in isolated FDB fibers. Pharmacological inhibition and genetic knockdown of Nox2 activity prevented SMase induced ROS production and provided protection against decreased force production in the diaphragm. In contrast, genetic overexpression of superoxide dismutase within the mitochondria did not prevent increased ROS production and offered no protection against decreased diaphragm function in response to SMase. Our study shows that SMase induced ROS production occurs in specific sub-cellular regions of skeletal muscle; however, the increased ROS does not completely account for the decrease in muscle function. PMID:25653619

  13. A computational model of cerebrospinal fluid production and reabsorption driven by Starling forces.

    PubMed

    Buishas, Joel; Gould, Ian G; Linninger, Andreas A

    2014-10-01

    Experimental evidence has cast doubt on the classical model of river-like cerebrospinal fluid (CSF) flow from the choroid plexus to the arachnoid granulations. We propose a novel model of water transport through the parenchyma from the microcirculation as driven by Starling forces. This model investigates the effect of osmotic pressure on water transport between the cerebral vasculature, the extracellular space (ECS), the perivascular space (PVS), and the CSF. A rigorous literature search was conducted focusing on experiments which alter the osmolarity of blood or ventricles and measure the rate of CSF production. Investigations into the effect of osmotic pressure on the volume of ventricles and the flux of ions in the blood, choroid plexus epithelium, and CSF are reviewed. Increasing the osmolarity of the serum via a bolus injection completely inhibits nascent fluid flow production in the ventricles. A continuous injection of a hyperosmolar solution into the ventricles can increase the volume of the ventricle by up to 125%. CSF production is altered by 0.231 μL per mOsm in the ventricle and by 0.835 μL per mOsm in the serum. Water flux from the ECS to the CSF is identified as a key feature of intracranial dynamics. A complete mathematical model with all equations and scenarios is fully described, as well as a guide to constructing a computational model of intracranial water balance dynamics. The model proposed in this article predicts the effects the osmolarity of ECS, blood, and CSF on water flux in the brain, establishing a link between osmotic imbalances and pathological conditions such as hydrocephalus and edema. PMID:25358881

  14. Aerosol Radiative Forcing Estimates from South Asian Clay Brick Production Based on Direct Emission Measurements

    NASA Astrophysics Data System (ADS)

    Weyant, C.; Athalye, V.; Ragavan, S.; Rajarathnam, U.; Kr, B.; Lalchandani, D.; Maithel, S.; Malhotra, G.; Bhanware, P.; Thoa, V.; Phuong, N.; Baum, E.; Bond, T. C.

    2012-12-01

    About 150-200 billion clay bricks are produced in India every year. Most of these bricks are fired in small-scale traditional kilns that burn coal or biomass without pollution controls. Reddy and Venkataraman (2001) estimated that 8% of fossil fuel related PM2.5 emissions and 23% of black carbon emissions in India are released from brick production. Few direct emissions measurements have been done in this industry and black carbon emissions, in particular, have not been previously measured. In this study, 9 kilns representing five common brick kiln technologies were tested for aerosol properties and gaseous pollutant emissions, including optical scattering and absorption and thermal-optical OC/EC. Simple relationships are then used to estimate the radiative-forcing impact. Kiln design and fuel quality greatly affect the overall emission profiles and relative climate warming. Batch production kilns, such as the Downdraft kiln, produce the most PM2.5 (0.97 gPM2.5/fired brick) with an OC/EC fraction of 0.3. Vertical Shaft Brick kilns using internally mixed fuels produce the least PM (0.09 gPM2.5/kg fired brick) with the least EC (OC/EC = 16.5), but these kilns are expensive to implement and their use throughout Southern Asia is minimal. The most popular kiln in India, the Bull's Trench kiln, had fewer emissions per brick than the Downdraft kiln, but an even higher EC fraction (OC/EC = 0.05). The Zig-zag kiln is similar in structure to the Bull's Trench kiln, but the emission factors are significantly lower: 50% reduction for CO, 17% for PM2.5 and 60% for black carbon. This difference in emissions suggests that converting traditional Bull's Trench kilns into less polluting Zig-zag kilns would result in reduced atmospheric warming from brick production.

  15. Treatment of allergic rhinitis: effect on occupation productivity and work force costs.

    PubMed

    Fireman, P

    1997-01-01

    Allergic rhinitis, one of the most common chronic illnesses, can have a negative impact on occupational productivity in the work-place. Allergic rhinitis affects over 13 million workers (6.15 million men and 6.11 million women) of the United States work force. Work place productivity can be reduced in the several ways: (1) Employee works at suboptimal efficiency because of the disease or its treatment; (2) employee takes a sick day away from work because of allergic rhinitis or its complications; (3) employee takes time off from work to care for or transport a child or dependent who needs care for allergic rhinitis or its complications, and (4) worker takes time off because of a work-related injury related to the disease or the medication used to treat the illness. Although nonsedating antihistamines and intranasal anti-inflammatory medications have been developed as effective therapies and are available as prescription drugs, many workers (50%) indicate that they manage their allergic rhinitis with over-the-counter medications. Most of these over-the-counter medicines contain sedating antihistamines which are known to alter cognitive and motor function. To determine whether the medications used by 3394 members of a health maintenance organization were associated with incident work-related injury, they were compared to two control groups selected from the membership and matched for age, gender, and Standard Industrial Classification Code of their employer. Medication use was determined from pharmacy data. The injuries included 496 fractures on dislocations, 2728 open, crushing, or superficial injuries, 176 burns, and 63 internal injuries. The risk of injury was statistically significantly elevated among users of sedating antihistamines. Utilizing demographic data the annual cost of last productivity to employers and society as the result of allergic rhinitis and its therapy with the over-the-counter sedating antihistamines is estimated to be greater than $4 billion

  16. Interaction of finger enslaving and error compensation in multiple finger force production

    PubMed Central

    Martin, Joel R.; Latash, Mark L.; Zatsiorsky, Vladimir M.

    2009-01-01

    Previous studies have documented two patterns of finger interaction during multi-finger pressing tasks, enslaving and error compensation, which do not agree with each other. Enslaving is characterized by positive correlation between instructed (master) and non-instructed (slave) finger(s) while error compensation can be described as a pattern of negative correlation between master and slave fingers. We hypothesize that pattern of finger interaction, enslaving or compensation, depends on the initial force level and the magnitude of the targeted force change. Subjects were instructed to press with four fingers (I - index, M - middle, R - ring, and L - little) from a specified initial force to a target forces following a ramp target line. Force-force relations between master and each of three slave fingers were analyzed during the ramp phase of trials by calculating correlation coefficients within each master-slave pair and then 2-factor ANOVA was performed to determine effect of initial force and force increase on the correlation coefficients. It was found that, as initial force increased, the value of the correlation coefficient decreased and in some cases became negative, i.e. the enslaving transformed into error compensation. Force increase magnitude had a smaller effect on the correlation coefficients. The observations support the hypothesis that the pattern of inter-finger interaction—enslaving or compensation—depends on the initial force level and, to a smaller degree, on the targeted magnitude of the force increase. They suggest that the controller views tasks with higher steady-state forces and smaller force changes as implying a requirement to avoid large changes in the total force. PMID:18985331

  17. Production of high specific activity silicon-32

    DOEpatents

    Phillips, Dennis R.; Brzezinski, Mark A.

    1994-01-01

    A process for preparation of silicon-32 is provide and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution to from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidization state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided.

  18. Activated Corrosion Product Analysis. Analytical Approach.

    SciTech Connect

    Golubov, Stanislav I; Busby, Jeremy T; Stoller, Roger E

    2010-01-01

    The presence of activated corrosion products (ACPs) in a water cooling system is a key factor in the licensing of ITER and affects nuclear classification, which governs design and operation. The objective of this study is to develop a method to accurately estimate radionuclide concentrations during ITER operation in support of nuclear classification. A brief overview of the PACTITER numerical code, which is currently used for ACP estimation, is presented. An alternative analytical approach for calculation of ACPs, which can also be used for validation of existing numerical codes, including PACTITER, has been proposed. A continuity equation describing the kinetics of accumulation of radioactive isotopes in a water cooling system in the form of a closed ring has been formulated, taking into account the following processes: production of radioactive elements and their decay, filtration, and ACP accumulation in filter system. Additional work is needed to more accurately assess the ACP inventory in the cooling water system, including more accurate simulation of the Tokamak cooling water system (TCWS) operating cycle and consideration of material corrosion, release, and deposition rates.

  19. Production of high specific activity silicon-32

    SciTech Connect

    Phillips, D.R.; Brzezinski, M.A.

    1994-09-13

    A process for the preparation of silicon-32 is provided and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution to from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidization state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided.

  20. Force control in chronic stroke.

    PubMed

    Kang, Nyeonju; Cauraugh, James H

    2015-05-01

    Force control deficits are common dysfunctions after a stroke. This review concentrates on various force control variables associated with motor impairments and suggests new approaches to quantifying force control production and modulation. Moreover, related neurophysiological mechanisms were addressed to determine variables that affect force control capabilities. Typically, post stroke force control impairments include: (a) decreased force magnitude and asymmetrical forces between hands, (b) higher task error, (c) greater force variability, (d) increased force regularity, and (e) greater time-lag between muscular forces. Recent advances in force control analyses post stroke indicated less bimanual motor synergies and impaired low-force frequency structure. Brain imaging studies demonstrate possible neurophysiological mechanisms underlying force control impairments: (a) decreased activation in motor areas of the ipsilesional hemisphere, (b) increased activation in secondary motor areas between hemispheres, (c) cerebellum involvement, and (d) relatively greater interhemispheric inhibition from the contralesional hemisphere. Consistent with identifying neurophysiological mechanisms, analyzing bimanual motor synergies as well as low-force frequency structure will advance our understanding of post stroke force control. PMID:25704075

  1. Selected demonstration and educational products/activities

    SciTech Connect

    Williams, R.J.; Mann, H.C.

    1992-07-01

    The information in this paper was assembled for several informal presentations to a variety of visitor groups during the summer of 1992. A number of staff members at TVA`s National Fertilizer and Environmental Research Center (NFERC) found it useful as a quick overview for their use and for their sharing with external colleagues and customers. The paper is not meant to be an exhaustive list or explanation of all products and services available from NFERC. However, the authors believe it will give a flavor and tenor of some of the ongoing activities of the Center, especially those activities relating to the retail fertilizer dealer. Programs over the years have focused on key aspects of nutrient efficiency and management. TVA is uniquely positioned to assist the fertilizer industry and US agriculture in protecting the environment from potential adverse environmental impacts of agriculture, especially for fertilizer and the attendant agrichemicals. TVA has the technical base and an ongoing working relationship with the fertilizer industry in technology development and introduction. Dealer education is very important in TVA programs in two aspects: (1) education for the dealer in meeting new environmental stewardship challenges from an operational perspective; and (2) education for the dealer in meeting the site-specific information needs of the farmer.

  2. Production of radioisotopes by direct electron activation.

    PubMed

    Weeks, K J; O'Shea, P G

    1998-04-01

    High-energy electrons bombarded on materials can induce radioactivity by either directly knocking out neutrons or by first converting a fraction of the electron kinetic energy into electromagnetic energy, with subsequent neutron emission induced by the photons produced. The purpose of this paper was to develop a calculation method for estimating neutron emission and radionuclide production by high-energy (15-25 MeV) electrons directly interacting with a nucleus. The reaction (e,n) is considered using the method of virtual photons. The cross section for electron bombardment of lead, tantalum, rhenium, and tungsten targets is calculated. The electron cross sections are roughly 100 times less than the corresponding photon cross sections. The cross section increases monotonically with incident energy. A traveling wave linear accelerator was used for a qualitative test of the magnitude and energy dependence of the calculated cross sections. Tantalum was bombarded with electrons and the resultant emission of neutrons was inferred from the induced activation of 180Ta. The energy dependence and magnitude of the calculated electron cross sections agree with experiment within experimental uncertainties. It is concluded that accurate estimates of electron activation via the direct process is possible. PMID:9571615

  3. Production of activated carbon from TCR char

    NASA Astrophysics Data System (ADS)

    Stenzel, Fabian; Heberlein, Markus; Klinner, Tobias; Hornung, Andreas

    2016-04-01

    The utilization of char for adsorptive purposes is known since the 18th century. At that time the char was made of wood or bones and used for decoloration of fluids. In the 20th century the production of activated carbon in an industrial scale was started. The today's raw materials for activated carbon production are hard coal, peat, wood or coconut shells. All these materials entail costs especially the latter. Thus, the utilization of carbon rich residues (biomass) is an interesting economic opportunity because it is available for no costs or even can create income. The char is produced by thermo-catalytic reforming (TCR®). This process is a combination of an intermediate pyrolysis and subsequently a reforming step. During the pyrolysis step the material is decomposed in a vapor and a solid carbon enriched phase. In the second step the vapor and the solid phase get in an intensive contact and the quality of both materials is improved via the reforming process. Subsequently, the condensables are precipitated from the vapor phase and a permanent gas as well as oil is obtained. Both are suitable for heat and power production which is a clear advantage of the TCR® process. The obtained biochar from the TCR® process has special properties. This material has a very low hydrogen and oxygen content. Its stability is comparable to hard coal or anthracite. Therefore it consists almost only of carbon and ash. The latter depends from input material. Furthermore the surface structure and area can be influenced during the reforming step. Depending from temperature and residence time the number of micro pores and the surface area can be increased. Preliminary investigations with methylene blue solution have shown that a TCR® char made of digestate from anaerobic digestion has adsorptive properties. The decoloration of the solution was achieved. A further influencing factor of the adsorption performance is the particle size. Based on the results of the preliminary tests a

  4. 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.

  5. 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

  6. 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

  7. 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

  8. 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

  9. Evaluation of precipitation products to force a global flood and drought prediction system

    NASA Astrophysics Data System (ADS)

    Voisin, N.; Lettenmaier, D. P.; Wood, E. F.

    2005-12-01

    Droughts and floods are pervasive natural hazards. The annual cost of U.S. droughts is in the range $6-8B, and estimated U.S. annual flood losses are only slightly less. Global flood and drought losses are almost certainly much higher. Nonetheless, there is at present no system for forecasting of floods and droughts globally, although the potential now exists. The pilot phase of a project to generate global flood and drought predictions routinely is presented. It draws heavily from the experimental North American Land Data Assimilation System (N-LDAS) and the companion Global Land Data Assimilation System (G-LDAS) for development of nowcasts, and the University of Washington Experimental Hydrologic Prediction System to develop ensemble hydrologic forecasts based on the NCEP Global Forecast System for lead times from seven days to six months. In retrospective testing, the system, which uses the Variable Infiltration Capacity (VIC) macroscale hydrology model to make predictions of streamflow and soil moisture, is driven by the GPCP 1DD global precipitation products, and ECMWF surface air temperature products. Downward solar and longwave radiation, surface relative humidity, and other model forcings are derived from relationships with the daily temperature range. The initial system is implemented globally at one-half degree spatial resolution. Characteristics errors in the precipitation data into the hydrological model represent the best attainable forecasts, where errors are being estimated from differences between the GPCP 1DD, ERA-40 and a 50-year retrospective data set produced by the University of Washington and Princeton University. Differences in precipitation between the different global data sets and their resulting hydrological differences are evaluated for the 1997-2002 period for a number of major global rivers, and for specific events like the Mekong and Elbe River floods in 2002, the Mozambique floods in 2000, the Mozambique drought in 2001 and the

  10. Importance of anisotropy in detachment rates for force production and cargo transport by a team of motor proteins.

    PubMed

    Takshak, Anjneya; Kunwar, Ambarish

    2016-05-01

    Many cellular processes are driven by collective forces generated by a team consisting of multiple molecular motor proteins. One aspect that has received less attention is the detachment rate of molecular motors under mechanical force/load. While detachment rate of kinesin motors measured under backward force increases rapidly for forces beyond stall-force; this scenario is just reversed for non-yeast dynein motors where detachment rate from microtubule decreases, exhibiting a catch-bond type behavior. It has been shown recently that yeast dynein responds anisotropically to applied load, i.e. detachment rates are different under forward and backward pulling. Here, we use computational modeling to show that these anisotropic detachment rates might help yeast dynein motors to improve their collective force generation in the absence of catch-bond behavior. We further show that the travel distance of cargos would be longer if detachment rates are anisotropic. Our results suggest that anisotropic detachment rates could be an alternative strategy for motors to improve the transport properties and force production by the team. PMID:26890030

  11. Force production during squats performed with a rotational resistance device under stable versus unstable conditions

    PubMed Central

    Moras, Gerard; Vázquez-Guerrero, Jairo

    2015-01-01

    [Purpose] Force production during a squat action on a rotational resistance device (RRD) under stable and unstable conditions. [Subjects and Methods] Twenty-one healthy males were asked to perform six sets of six repetitions of squats on an RRD on either stable or unstable surfaces. The stable and unstable sets were performed on different days. Muscular outputs were obtained from a linear encoder and a strain gauge fixed to a vest. [Results] Overall, the results showed no significant differences for any of the dependent variables across exercise modes. Forcemean outputs were higher in the concentric phase than in the eccentric phase for each condition, but there were no differences in velocity, time or displacement. The forcepeak was similar in the eccentric and concentric phases of movement under both stable and unstable conditions. There were no significant differences in forcemean between sets per condition or between conditions. [Conclusion] These results suggest that performing squats with a RRD achieves similar forcemean and forcepeak under stable and unstable conditions. The forcepeak produced is also similar in concentric and eccentric phases. PMID:26696707

  12. Force production during squats performed with a rotational resistance device under stable versus unstable conditions.

    PubMed

    Moras, Gerard; Vázquez-Guerrero, Jairo

    2015-11-01

    [Purpose] Force production during a squat action on a rotational resistance device (RRD) under stable and unstable conditions. [Subjects and Methods] Twenty-one healthy males were asked to perform six sets of six repetitions of squats on an RRD on either stable or unstable surfaces. The stable and unstable sets were performed on different days. Muscular outputs were obtained from a linear encoder and a strain gauge fixed to a vest. [Results] Overall, the results showed no significant differences for any of the dependent variables across exercise modes. Forcemean outputs were higher in the concentric phase than in the eccentric phase for each condition, but there were no differences in velocity, time or displacement. The forcepeak was similar in the eccentric and concentric phases of movement under both stable and unstable conditions. There were no significant differences in forcemean between sets per condition or between conditions. [Conclusion] These results suggest that performing squats with a RRD achieves similar forcemean and forcepeak under stable and unstable conditions. The forcepeak produced is also similar in concentric and eccentric phases. PMID:26696707

  13. Production and destruction of eddy kinetic energy in forced submesoscale eddy-resolving simulations

    NASA Astrophysics Data System (ADS)

    Mukherjee, Sonaljit; Ramachandran, Sanjiv; Tandon, Amit; Mahadevan, Amala

    2016-09-01

    We study the production and dissipation of the eddy kinetic energy (EKE) in a submesoscale eddy field forced with downfront winds using the Process Study Ocean Model (PSOM) with a horizontal grid resolution of 0.5 km. We simulate an idealized 100 m deep mixed-layer front initially in geostrophic balance with a jet in a domain that permits eddies within a range of O(1 km-100 km). The vertical eddy viscosities and the dissipation are parameterized using four different subgrid vertical mixing parameterizations: the k - ɛ , the KPP, and two different constant eddy viscosity and diffusivity profiles with a magnitude of O(10-2m2s-1) in the mixed layer. Our study shows that strong vertical eddy viscosities near the surface reduce the parameterized dissipation, whereas strong vertical eddy diffusivities reduce the lateral buoyancy gradients and consequently the rate of restratification by mixed-layer instabilities (MLI). Our simulations show that near the surface, the spatial variability of the dissipation along the periphery of the eddies depends on the relative alignment of the ageostrophic and geostrophic shear. Analysis of the resolved EKE budgets in the frontal region from the simulations show important similarities between the vertical structure of the EKE budget produced by the k - ɛ and KPP parameterizations, and earlier LES studies. Such an agreement is absent in the simulations using constant eddy-viscosity parameterizations.

  14. 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…

  15. Equifinality and its violations in a redundant system: multifinger accurate force production

    PubMed Central

    Wilhelm, Luke; Zatsiorsky, Vladimir M.

    2013-01-01

    We explored a hypothesis that transient perturbations applied to a redundant system result in equifinality in the space of task-related performance variables but not in the space of elemental variables. The subjects pressed with four fingers and produced an accurate constant total force level. The “inverse piano” device was used to lift and lower one of the fingers smoothly. The subjects were instructed “not to intervene voluntarily” with possible force changes. Analysis was performed in spaces of finger forces and finger modes (hypothetical neural commands to fingers) as elemental variables. Lifting a finger led to an increase in its force and a decrease in the forces of the other three fingers; the total force increased. Lowering the finger back led to a drop in the force of the perturbed finger. At the final state, the sum of the variances of finger forces/modes computed across repetitive trials was significantly higher than the variance of the total force/mode. Most variance of the individual finger force/mode changes between the preperturbation and postperturbation states was compatible with constant total force. We conclude that a transient perturbation applied to a redundant system leads to relatively small variance in the task-related performance variable (equifinality), whereas in the space of elemental variables much more variance occurs that does not lead to total force changes. We interpret the results within a general theoretical scheme that incorporates the ideas of hierarchically organized control, control with referent configurations, synergic control, and the uncontrolled manifold hypothesis. PMID:23904497

  16. Non-tectonic base level forcings drive widespread transient incision and relief production in the waning Appalachian orogen

    NASA Astrophysics Data System (ADS)

    Prince, P. S.; Richardson, R. P.

    2012-12-01

    The development of knickpoints and steep bedrock gorges within otherwise low-relief landscapes of the Appalachian Highlands has long interested geomorphologists. While large tracts of muted Appalachian topography appear consistent with slow, steady exhumation of a thickened crustal root, active gorge development into lower-relief uplands suggests that Appalachian river systems have been re-energized to incise into bedrock and increase relief. Orogen-scale analysis of incision patterns, fluvial profiles, and surficial deposits indicate that two main sources of non-tectonic base level drop superimposed on the slowly-exhuming Appalachian landscape can explain the Cenozoic relief production observed. Along the Eastern Continental Divide on the southeast margin of the Highlands, repeated capture of headwaters of elevated, landward-draining streams of the Blue Ridge by Atlantic basin streams maintains the oversteepened slopes and bedrock gorges of the Blue Ridge Escarpment zone. Capture events induce a transient erosional response in which rapid knickpoint retreat carves deep gorges into the captured basin, ultimately adjusting topography to match the rest of the Atlantic slope. In the lower reaches of landward Appalachian rivers still following courses to the continental interior, hillslope steepening in the wake of migrating knickpoints is apparent against the backdrop of a comparatively low-relief upland. This landscape suggests that landward base level drop, possibly due to rapid, glacially-forced Plio-Pleistocene drainage rearrangement, has initiated transgressive waves of incision to adjust Highlands topography to the recently-established continental interior drainage pattern. Encroachment of both the post-rift seaward base level and the modern landward base level forces a rapid release of potential energy stored in the elevated Highlands, energizing streams to incise into bedrock without the introduction of new tectonic energy. The southern Appalachian landscape

  17. 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

  18. 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

  19. Reliability of Selected Measures of Movement Control and Force Production on Children Four Through Ten Years of Age.

    ERIC Educational Resources Information Center

    Heston, Melissa; And Others

    1986-01-01

    The purpose of this study was to establish tentative reliability estimates for movement control and force production tasks as the initial phase of a cross-cultural motor-performance study. Ten boys and ten girls for each of seven age groups (ages four through ten) performed four specific tasks. Results are discussed. (MT)

  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. Effects of Constant and Doublet Frequency Electrical Stimulation Patterns on Force Production of Knee Extensor Muscles

    PubMed Central

    Cometti, Carole; Babault, Nicolas; Deley, Gaëlle

    2016-01-01

    This study compared knee extensors’ neuromuscular fatigue in response to two 30-minute stimulation patterns: constant frequency train (CFT) and doublet frequency train (DFT). Fifteen men underwent two separate sessions corresponding to each pattern. Measurements included torque evoked by each contraction and maximal voluntary contractions (MVC) measured before and immediately after the stimulation sessions. In addition, activation level and torque evoked during doublets (Pd) and tetanic contractions at 80-Hz (P80) and 20-Hz (P20) were determined in six subjects. Results indicated greater mean torque during the DFT stimulation session as compared with CFT. But, no difference was obtained between the two stimulation patterns for MVC and evoked torque decreases. Measurements conducted in the subgroup depicted a significant reduction of Pd, P20 and P80. Statistical analyses also revealed bigger P20 immediate reductions after CFT than after DFT. We concluded that DFT could be a useful stimulation pattern to produce and maintain greater force with quite similar fatigue than CFT. PMID:27167066

  2. 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

  3. Time Estimation in Young Children: An Initial Force Rule Governing Time Production.

    ERIC Educational Resources Information Center

    Droit-Volet, Sylvie

    1998-01-01

    Studied time estimation for a button-pressing response in 3- and 5.5-year-olds under "minimal,""temporal," and "force" instructions. Found that force--but not temporal--instructions improved 3-year-olds' timing accuracy. When instructed to press harder, they pressed longer. Older children were more accurate with temporal than with force…

  4. 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.

  5. 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.

  6. Comparison of TOPEX/Poseidon Sea Level and Linear Model Results forced by Various Wind Products for the Tropical Pacific

    NASA Technical Reports Server (NTRS)

    Hackert, Eric C.; Busalacchi, Antonio J.

    1997-01-01

    The goal of this paper is to compare TOPEX/Posaidon (T/P) sea level with sea level results from linear ocean model experiments forced by several different wind products for the tropical Pacific. During the period of this study (October 1992 - October 1995), available wind products include satellite winds from the ERS-1 scatterometer product of [HALP 97] and the passive microwave analysis of SSMI winds produced using the variational analysis method (VAM) of [ATLA 91]. In addition, atmospheric GCM winds from the NCEP reanalysis [KALN 96], ECMWF analysis [ECMW94], and the Goddard EOS-1 (GEOS-1) reanalysis experiment [SCHU 93] are available for comparison. The observed ship wind analysis of FSU [STRI 92] is also included in this study. The linear model of [CANE 84] is used as a transfer function to test the quality of each of these wind products for the tropical Pacific. The various wind products are judged by comparing the wind-forced model sea level results against the T/P sea level anomalies. Correlation and RMS difference maps show how well each wind product does in reproducing the T/P sea level signal. These results are summarized in a table showing area average correlations and RMS differences. The large-scale low-frequency temporal signal is reproduced by all of the wind products, However, significant differences exist in both amplitude and phase on regional scales. In general, the model results forced by satellite winds do a better job reproducing the T/P signal (i.e. have a higher average correlation and lower RMS difference) than the results forced by atmospheric model winds.

  7. MODELING MAGNETIC FIELD STRUCTURE OF A SOLAR ACTIVE REGION CORONA USING NONLINEAR FORCE-FREE FIELDS IN SPHERICAL GEOMETRY

    SciTech Connect

    Guo, Y.; Ding, M. D.; Liu, Y.; Sun, X. D.; DeRosa, M. L.; Wiegelmann, T.

    2012-11-20

    We test a nonlinear force-free field (NLFFF) optimization code in spherical geometry using an analytical solution from Low and Lou. Several tests are run, ranging from idealized cases where exact vector field data are provided on all boundaries, to cases where noisy vector data are provided on only the lower boundary (approximating the solar problem). Analytical tests also show that the NLFFF code in the spherical geometry performs better than that in the Cartesian one when the field of view of the bottom boundary is large, say, 20 Degree-Sign Multiplication-Sign 20 Degree-Sign . Additionally, we apply the NLFFF model to an active region observed by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory (SDO) both before and after an M8.7 flare. For each observation time, we initialize the models using potential field source surface (PFSS) extrapolations based on either a synoptic chart or a flux-dispersal model, and compare the resulting NLFFF models. The results show that NLFFF extrapolations using the flux-dispersal model as the boundary condition have slightly lower, therefore better, force-free, and divergence-free metrics, and contain larger free magnetic energy. By comparing the extrapolated magnetic field lines with the extreme ultraviolet (EUV) observations by the Atmospheric Imaging Assembly on board SDO, we find that the NLFFF performs better than the PFSS not only for the core field of the flare productive region, but also for large EUV loops higher than 50 Mm.

  8. What Geological, Economic, or Policy Forces Might Limit Fossil Fuel Production?

    NASA Astrophysics Data System (ADS)

    Heinberg, R.

    2015-12-01

    In order to ensure a 50% chance of keeping global temperatures from exceeding 2°C above pre-industrial levels, it has been estimated that total carbon dioxide emissions between 2011-2050 must be capped at roughly 1,100 gigatons.[1] However, some estimates calculate that global fossil fuel reserves—including unconventional oil and gas—hold at least three times this amount of potential greenhouse gas emissions.[2]What socio-political, technological, or economic forces are most likely to keep these energy resources from being burned? While it is difficult to predict with specificity what combination of technological, geological, or human factors will significantly minimize global fossil fuel production, there are at least four key potential drivers: 1. Under-investment and the economics of unconventional oil and natural gas; 2. International policy, driven by citizen demand and leadership from key nations; 3. Massive deployment of renewable energy sources and other technological solutions; and 4. Large-scale energy curtailment resulting from global economic contraction. We will explore the implications, viability, and consequences of each of these potential factors. [1] [1]United Nations Framework Convention on Climate Change (UNFCC) Report of the Conference of the Parties on its Fifteenth Session, held in Copenhagen from 7 to 19 December 2009. Part Two: Action taken by the Conference of the Parties at its Fifteenth Session. United Nations Climate Change Conf. Report 43 http://unfccc.int/resource/docs/2009/cop15/eng/11a01.pdf (UNFCC, 2009) [2] Raupach, M. R. et al. Sharing a quota on cumulative carbon emissions. Nature Clim. Chang. 4, 873-879 (2014)

  9. Structural Forces and the Production of TB-related Stigma among Haitians in Two Contexts

    PubMed Central

    Coreil, Jeannine; Mayard, Gladys; Simpson, Kelly M; Lauzardo, Michael; Zhu, Yiliang; Weiss, Mitchell

    2012-01-01

    In recent years renewed interest in health-related stigma has underscored the importance of better understanding the structural underpinnings of stigma processes. This study investigated the influence of sociocultural context on perceived components of tuberculosis-related stigma in non-affected persons by comparing Haitians living in South Florida, USA, with Haitians residing in Léogane Commune, Haiti. Using the methods of cultural epidemiology, a two-phase study based on fieldwork between 2004–07 collected ethnographic data on the cultural context and components of tuberculosis (TB) stigma, and administered a stigma scale developed specifically for these populations. Thematic analysis of stigma components expressed in interviews, focus groups and observation revealed commonalities as well as distinctive emphases of TB stigma in the two comparison groups. Factor analyses of stigma scale scores confirmed the thematic differences revealed in ethnographic findings and highlight the influence of political and economic factors in shaping the meaning and experience of illness. Perceived components of TB stigma among Haitians in South Florida incorporated aspects of Haitian identity as a negatively stereotyped minority community within the larger society, while in Haiti, stigma was associated primarily with poverty, malnutrition, and HIV co-infection. Discussion of findings focuses on the social production of perceived and anticipated stigma as it is influenced by structural forces including the influences of politics, economics, institutional policies, and health service delivery structures. The findings also demonstrate the value of a transnational framework encompassing both sending and receiving countries for understanding TB related stigma in immigrant communities. PMID:20724052

  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. 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

  14. 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

  15. Force and number of myosin motors during muscle shortening and the coupling with the release of the ATP hydrolysis products

    PubMed Central

    Caremani, Marco; Melli, Luca; Dolfi, Mario; Lombardi, Vincenzo; Linari, Marco

    2015-01-01

    The chemo-mechanical cycle of the myosin II–actin reaction in situ has been investigated in Ca2+-activated skinned fibres from rabbit psoas, by determining the number and strain (s) of myosin motors interacting during steady shortening at different velocities (V) and the effect of raising inorganic phosphate (Pi) concentration. It was found that in control conditions (no added Pi), shortening at V ≤ 350 nm s–1 per half-sarcomere, corresponding to force (T) greater than half the isometric force (T0), decreases the number of myosin motors in proportion to the reduction of T, so that s remains practically constant and similar to the T0 value independent of V. At higher V the number of motors decreases less than in proportion to T, so that s progressively decreases. Raising Pi concentration by 10 mm, which reduces T0 and the number of motors by 40–50%, does not influence the dependence on V of number and strain. A model simulation of the myosin–actin reaction in which the structural transitions responsible for the myosin working stroke and the release of the hydrolysis products are orthogonal explains the results assuming that Pi and then ADP are released with rates that increase as the motor progresses through the working stroke. The rate of ADP release from the conformation at the end of the working stroke is also strain-sensitive, further increasing by one order of magnitude within a few nanometres of negative strain. These results provide the molecular explanation of the relation between the rate of energy liberation and the load during muscle contraction. Key points Muscle contraction is due to cyclical ATP-driven working strokes in the myosin motors while attached to the actin filament. Each working stroke is accompanied by the release of the hydrolysis products, orthophosphate and ADP. The rate of myosin–actin interactions increases with the increase in shortening velocity. We used fast half-sarcomere mechanics on skinned muscle fibres to

  16. Finger synergies during multi-finger cyclic production of moment of force

    PubMed Central

    Zhang, Wei; Zatsiorsky, Vladimir M.

    2010-01-01

    We investigated multi-finger synergies stabilizing the total moment of force and the total force when the subjects produced a quick cyclic change in the total moment of force. The seated subjects performed the task with the fingers of the dominant arm while paced by the metronome at 1.33 Hz. They were required to produce a rhythmic, sine-like change in the total pronation–supination moment of force computed with respect to the midpoint between the middle and ring fingers. The framework of the uncontrolled manifold hypothesis was used to compute indices of stabilization of the total moment and of the total force across 20 cycles. Variance of the total moment showed a cyclic pattern with peaks close to the peak rate of the moment change. Variance of the total force was maximal close to peak moment into supination. Higher magnitudes of the moment directed against the required moment direction (antagonist moment) were produced by individual fingers during supination efforts as compared to pronation efforts. Indices of multi-finger synergies showed across-trials stabilization of the total moment over the whole cycle but not of the total force. These indices were smaller during supination efforts. We conclude that the central nervous system facilitates multi-finger synergies stabilizing the total rotational action across a variety of tasks. Synergies stabilizing the total force are not seen in tasks that do not explicitly require accurate force control. Pronation efforts are performed more efficiently and with better stabilization of the action. PMID:16944107

  17. 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.

  18. Repetitive Transcranial Magnetic Stimulation Attenuates the Perception of Force Output Production in Non-Exercised Hand Muscles after Unilateral Exercise

    PubMed Central

    Goodall, Stuart; St Clair Gibson, Alan; Voller, Bernhard; Lomarev, Mike; Howatson, Glyn; Dang, Nguyet; Hortobágyi, Tibor; Hallett, Mark

    2013-01-01

    We examined whether unilateral exercise creates perception bias in the non-exercised limb and ascertained whether rTMS applied to the primary motor cortex (M1) interferes with this perception. All participants completed 4 interventions: 1) 15-min learning period of intermittent isometric contractions at 35% MVC with the trained hand (EX), 2) 15-min learning period of intermittent isometric contractions at 35% MVC with the trained hand whilst receiving rTMS over the contralateral M1 (rTMS+EX); 3) 15-min of rTMS over the ‘trained’ M1 (rTMS) and 4) 15-min rest (Rest). Pre and post-interventions, the error of force output production, the perception of effort (RPE), motor evoked potentials (MEPs) and compound muscle action potentials (CMAPs) were measured in both hands. EX did not alter the error of force output production in the trained hand (Δ3%; P>0.05); however, the error of force output production was reduced in the untrained hand (Δ12%; P<0.05). rTMS+EX and rTMS alone did not show an attenuation in the error of force output production in either hand. EX increased RPE in the trained hand (9.1±0.5 vs. 11.3±0.7; P<0.01) but not the untrained hand (8.8±0.6 vs. 9.2±0.6; P>0.05). RPE was significantly higher after rTMS+EX in the trained hand (9.2±0.5 vs. 10.7±0.7; P<0.01) but ratings were unchanged in the untrained hand (8.5±0.6 vs. 9.2±0.5; P>0.05). The novel finding was that exercise alone reduced the error in force output production by over a third in the untrained hand. Further, when exercise was combined with rTMS the transfer of force perception was attenuated. These data suggest that the contralateral M1 of the trained hand might, in part, play an essential role for the transfer of force perception to the untrained hand. PMID:24278259

  19. Regional Attribution of Ozone Production and Associated Radiative Forcing: a Step to Crediting NOx Emission Reductions

    NASA Astrophysics Data System (ADS)

    Naik, V.; Mauzerall, D. L.; Horowitz, L.; Schwarzkopf, D.; Ramaswamy, V.; Oppenheimer, M.

    2004-12-01

    The global distribution of tropospheric ozone (O3) depends on the location of emissions of its precursors in addition to chemical and dynamical factors. The global picture of O3 forcing is, therefore, a sum of regional forcings arising from emissions of precursors from different sources. The Kyoto Protocol does not include ozone as a greenhouse gas, and emission reductions of ozone precursors made under Kyoto or any similar agreement would presently receive no credit. In this study, we quantitatively estimate the contribution of emissions of nitrogen oxides (NOx), the primary limiting O3 precursor in the non-urban atmosphere, from specific countries and regions of the world to global O3 concentration distributions. We then estimate radiative forcing resulting from the regional perturbations of NOx emissions. This analysis is intended as an early step towards incorporating O3 into the Kyoto Protocol or any successor agreement. Under such a system countries could obtain credit for improvements in local air quality that result in reductions of O3 concentrations because of the associated reductions in radiative forcing. We use the global chemistry transport model, MOZART-2, to simulate the global O3 distribution for base year 1990 and perturbations to this distribution caused by a 10% percent reduction in the base emissions of NOx from the United States, Europe, East Asia, India, South America, and Africa. We calculate the radiative forcing for the simulated base and perturbed O3 distributions using the GFDL radiative transfer model. The difference between the radiative forcing from O3 for the base and perturbed distributions provides an estimate of the marginal radiative forcing from a region's emissions of NOx. We will present a quantitative analysis of the magnitude, spatial, and temporal distribution of radiative forcing resulting from marginal changes in the NOx emissions from each region.

  20. 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…

  1. Population studies should reflect the criterion of productive forces and the viewpoint of a market-oriented economy.

    PubMed

    Peng, X

    1989-01-01

    This commentary is on the role of population studies in a market oriented economy which reflects Marxist theories on productive forces. Population development must not be viewed unidimensionally. Prior thinking focused on the mode of social production determining population development and vice versa. The assumption prevalent prior to 1978 was that there was no common pattern among different societies. This view was openly challenged in the 2nd national population science symposium in Chengdu, Sichuan Province. It was stated that population development is affected by production techniques in either capitalist or socialist countries. Further understanding of this relationship based on quantitative and qualitative research was required. Public ownership is the basis of a socialist economy. Marxist views were that populations in market or nonmarket economies are different, and population scholars need to study these relationships. There was a mistaken belief that a socialist economy was nonmarket oriented. Correcting the mistake meant taking into consideration migration, urbanization, employment, expenditure, and the relationship to reproduction, as well as rethinking the development patterns. When the price of the labor force differs from its value, the investment in population and population quality will be affected. This has led to rampant commercialization and higher school dropout rates. Short term interests predominate. The trend does not benefit the quality of the population or the promotion of social productive forces. Further examination is needed of the effects of urbanization on a planned market oriented economy with socialist public ownership. PMID:12316994

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. Heat production due to intracellular killing activity.

    PubMed

    Hayatsu, H; Masuda, S; Miyamae, T; Yamamura, M

    1990-09-01

    Using Saccharomyces ceravisiae, Candida albicans and Stapylococcus aureus, heat production during phagocytosis was measured in U937 cells which are capable of differentiating to monocytic phagocytes. No increase in heat production of non-differentiated U937 was observed since they were not phagocytic cells. However after differentiation to monocytic phagocytes by lymphokine, U937 cells produced a remarkable amount of heat during phagocytosis. Although Ehrlich ascites tumor cells sensitized with antibody were capable of engulfing S. aureus, no increase in heat nor in superoxide anion production during phagocytosis was detected. It was also found that no heat increase occurred in neutrophils from a patient with chronic granulomatous disease (CGD). It can thus be concluded that the heat production during phagocytosis is due to the intercellular killing process of phagocytic cells. PMID:2131646

  8. β-Alanine supplementation enhances human skeletal muscle relaxation speed but not force production capacity.

    PubMed

    Hannah, Ricci; Stannard, Rebecca Louise; Minshull, Claire; Artioli, Guilherme Giannini; Harris, Roger Charles; Sale, Craig

    2015-03-01

    β-Alanine (BA) supplementation improves human exercise performance. One possible explanation for this is an enhancement of muscle contractile properties, occurring via elevated intramuscular carnosine resulting in improved calcium sensitivity and handling. This study investigated the effect of BA supplementation on in vivo contractile properties and voluntary neuromuscular performance. Twenty-three men completed two experimental sessions, pre- and post-28 days supplementation with 6.4 g/day of BA (n = 12) or placebo (PLA; n = 11). During each session, force was recorded during a series of knee extensor contractions: resting and potentiated twitches and octet (8 pulses, 300 Hz) contractions elicited via femoral nerve stimulation; tetanic contractions (1 s, 1-100 Hz) via superficial muscle stimulation; and maximum and explosive voluntary contractions. BA supplementation had no effect on the force-frequency relationship, or the force responses (force at 25 and 50 ms from onset, peak force) of resting or potentiated twitches, and octet contractions (P > 0.05). Resting and potentiated twitch electromechanical delay and time-to-peak tension were unaffected by BA supplementation (P > 0.05), although half-relaxation time declined by 7-12% (P < 0.05). Maximum and explosive voluntary forces were unchanged after BA supplementation. BA supplementation had no effect on evoked force responses, implying that altered calcium sensitivity and/or release are not the mechanisms by which BA supplementation influences exercise performance. The reduced half-relaxation time with BA supplementation might, however, be explained by enhanced reuptake of calcium, which has implications for the efficiency of muscle contraction following BA supplementation. PMID:25539942

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Production of Local Acoustic Radiation Force to Constrain Direction of Microcapsules in Flow

    NASA Astrophysics Data System (ADS)

    Kohji Masuda,; Nobuyuki Watarai,; Ryusuke Nakamoto,; Yusuke Muramatsu,

    2010-07-01

    We have ever reported our attempt to control the direction of microcapsules in flow by acoustic radiation force. However, the diameter of capsules was too large to be applied in vivo. Furthermore, the acoustic radiation force affected only the focal area because focused ultrasound was used. Thus, we have improved our experiment by using microcapsules as small as blood cells and introducing a plane wave of ultrasound. We prepared an artificial blood vessel including a Y-form bifurcation established in two observation areas. Then, we newly defined the induction index to evaluate the difference in capsule density in two downstream paths. As a result, the optimum angle of ultrasound emission to induct to the desired path was derived. The induction index increased in proportion to the central frequency of ultrasound, which is affected by the aggregation of capsules to receive more acoustic radiation force.

  20. 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

  1. 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

  2. The Effects of Height and Distance on the Force Production and Acceleration in Martial Arts Strikes

    PubMed Central

    Bolander, Richard P.; Neto, Osmar Pinto; Bir, Cynthia A.

    2009-01-01

    Almost all cultures have roots in some sort of self defence system and yet there is relatively little research in this area, outside of a sports related environment. This project investigated different applications of strikes from Kung Fu practitioners that have not been addressed before in the literature. Punch and palm strikes were directly compared from different heights and distances, with the use of a load cell, accelerometers, and high speed video. The data indicated that the arm accelerations of both strikes were similar, although the force and resulting acceleration of the target were significantly greater for the palm strikes. Additionally, the relative height at which the strike was delivered was also investigated. The overall conclusion is that the palm strike is a more effective strike for transferring force to an object. It can also be concluded that an attack to the chest would be ideal for maximizing impact force and moving an opponent off balance. Key Points It has been determined that the palm strike is more effective than the punch for developing force and for transferring momentum, most likely the result of a reduced number of rigid links and joints. A strike at head level is less effective than a strike at chest level for developing force and transferring momentum. Distance plays an effect on the overall force and momentum changes, and most likely is dependent on the velocity of the limb and alignment of the bones prior to impact. The teaching of self defence for novices and law enforcement would benefit from including the palm strike as a high priority technique. PMID:24474886

  3. 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

  4. Ultrasound-assisted handling force reduction during the solar silicon wafers production.

    PubMed

    Saffar, S; Abdullah, A; Gouttebroze, S; Zhang, Z L

    2014-04-01

    Surface adhesion between wet wafers poses great challenges for silicon wafer handling. It has been shown that both the shear and normal handling forces of the solar silicon wafers can be dramatically reduced by using the ultrasound energy. Approximately 20 and 5 times reduction in horizontal and vertical forces were achieved by as low power as 10W, and a good agreement was found between the measured values and the predictions of a simple model for the effect of longitudinal vibration we developed. PMID:24434116

  5. 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.

  6. Polyphenols as active ingredients for cosmetic products.

    PubMed

    Zillich, O V; Schweiggert-Weisz, U; Eisner, P; Kerscher, M

    2015-10-01

    Polyphenols are secondary plant metabolites with antioxidant, anti-inflammatory and anti-microbial activity. They are ubiquitously distributed in the plant kingdom; high amounts contain, for example, green tea and grape seeds. Polyphenolic extracts are attractive ingredients for cosmetics and pharmacy due to their beneficial biological properties. This review summarizes the effects of polyphenols in the context of anti-ageing activity. We have explored in vitro studies, which investigate antioxidant activity, inhibition of dermal proteases and photoprotective activity, mostly studied using dermal fibroblasts or epidermal keratinocytes cell lines. Possible negative effects of polyphenols were also discussed. Further, some physicochemical aspects, namely the possible interactions with emulsifiers and the influence of the cosmetic formulation on the skin delivery, were reported. Finally, few clinical studies, which cover the anti-ageing action of polyphenols on the skin after topical application, were reviewed. PMID:25712493

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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

  12. Microbial production of sensory-active miraculin.

    PubMed

    Ito, Keisuke; Asakura, Tomiko; Morita, Yuji; Nakajima, Ken-ichiro; Koizumi, Ayako; Shimizu-Ibuka, Akiko; Masuda, Katsuyoshi; Ishiguro, Masaji; Terada, Tohru; Maruyama, Jun-ichi; Kitamoto, Katsuhiko; Misaka, Takumi; Abe, Keiko

    2007-08-24

    Miraculin (MCL), a tropical fruit protein, is unique in that it has taste-modifying activity to convert sourness to sweetness, though flat in taste at neutral pH. To obtain a sufficient amount of MCL to examine the mechanism involved in this sensory event at the molecular level, we transformed Aspergillus oryzae by introducing the MCL gene. Transformants were expressed and secreted a sensory-active form of MCL yielding 2 mg/L. Recombinant MCL resembled native MCL in the secondary structure and the taste-modifying activity to generate sweetness at acidic pH. Since the observed pH-sweetness relation seemed to reflect the imidazole titration curve, suggesting that histidine residues might be involved in the taste-modifying activity. H30A and H30,60A mutants were generated using the A. oryzae-mediated expression system. Both mutants found to have lost the taste-modifying activity. The result suggests that the histidine-30 residue is important for the taste-modifying activity of MCL. PMID:17592723

  13. Accurate production of time-varying patterns of the moment of force in multi-finger tasks

    PubMed Central

    Zhang, Wei; Zatsiorsky, Vladimir M.; Latash, Mark L.

    2010-01-01

    We investigated the production of time profiles of the total moment of force produced in isometric conditions by the four fingers of a hand. We hypothesized that these tasks would be associated with multi-finger synergies stabilizing the time profile of the total moment across trials but not necessarily stabilizing the time profile of the total force produced by the fingers. We also expected the multi-finger synergies to prevent an increase in the moment variability with its magnitude. Seated subjects pressed on force sensors with the four fingers of the right hand and produced two time profiles of the total moment of force, starting from a certain pronation effort, leading to a similar supination effort, and back to the initial pronation effort. One of the profiles was a sequence of straight lines (M-Ramp) while the other was a smooth curve (M-Sine). The subjects showed an increase in the total force during each task. This was accompanied by an increase in the force produced by the fingers opposing the required direction of the total moment—antagonist fingers. Variability of the total force and of the total moment showed complex, non-monotonic changes with the magnitude of the force and moment, respectively. In both tasks, the subjects showed patterns of co-variation of commands to fingers that stabilized the required moment profile over trials. The time profile of the total force was stabilized to a lesser degree or not stabilized at all. The share of fingers with larger moment arms (index finger for pronation efforts and little finger for supination efforts) was higher when the fingers acted to produce moments in a required direction but not necessarily when they acted as antagonists. The results demonstrate the existence of multi-finger synergies stabilizing the combined rotational action. They fit a hypothesis that stabilization of rotational actions may be a default strategy conditioned by everyday experience. The data also suggest that the mechanical

  14. Protective effects of lactic acid on force production in rat skeletal muscle.

    PubMed

    Nielsen, O B; de Paoli, F; Overgaard, K

    2001-10-01

    1. During strenuous exercise lactic acid accumulates producing a reduction in muscle pH. In addition, exercise causes a loss of muscle K(+) leading to an increased concentration of extracellular K(+) ([K(+)](o)). Individually, reduced pH and increased [K(+)](o) have both been suggested to contribute to muscle fatigue. 2. To study the combined effect of these changes on muscle function, isolated rat soleus muscles were incubated at a [K(+)](o) of 11 mM, which reduced tetanic force by 75 %. Subsequent addition of 20 mM lactic acid led, however, to an almost complete force recovery. A similar recovery was observed if pH was reduced by adding propionic acid or increasing the CO(2) tension. 3. The recovery of force was associated with a recovery of muscle excitability as assessed from compound action potentials. In contrast, acidification had no effect on the membrane potential or the Ca(2+) handling of the muscles. 4. It is concluded that acidification counteracts the depressing effects of elevated [K(+)](o) on muscle excitability and force. Since intense exercise is associated with increased [K(+)](o), this indicates that, in contrast to the often suggested role for acidosis as a cause of muscle fatigue, acidosis may protect against fatigue. Moreover, it suggests that elevated [K(+)](o) is of less importance for fatigue than indicated by previous studies on isolated muscles. PMID:11579166

  15. Force production mechanisms of a tangential jet on bodies at high alpha

    NASA Technical Reports Server (NTRS)

    Font, G. I.

    1992-01-01

    This work explores the mechanisms by which tangential slot blowing creates forces on a body at a high angle of attack. The study is conducted numerically by solving the three-dimensional, compressible-flow Navier-Stokes equations. A tangent-ogive cylinder configuration is used with the blowing slot located both on the nose and on the cylindrical part of the body. The angle of attack used is 30 deg., the Mach no. is 0.2 and the Reynolds no., based on diameter, is 52,000. Several conclusions were made concerning the physical mechanisms by which the jet interacts with the ambient flowfield to produce a side force: (1) A centrifugal force component is created at the wall due to the momentum of the jet being forced to follow the curvature of the surface. (2) A large amount of vorticity is added to the flowfield by the jet. In the region of the slot, the vorticity has the effect of inducing circulation around the body. Downstream of the slot, the vorticity alters the strength of the nose vortices. (3) The position of the nose vortices can be altered to the jet changing the location of separation. And (4), the jet has the ability to excite unstable behavior producing a global change in the character of the flow.

  16. Auditory Feedback: Effects on Vertical Force Production during Standing Up Following Stroke.

    ERIC Educational Resources Information Center

    Fowler, V.; Carr, J.

    1996-01-01

    Twelve individuals recovering from stroke were given a three-week period of rehabilitative training with or without auditory feedback. The purpose was to investigate weight distribution on the pattern of vertical force through the affected leg during standing up. Results indicated the training improved subjects' strength and muscle control, though…

  17. Mutagenic activity of disinfection by-products.

    PubMed Central

    Cognet, L; Courtois, Y; Mallevialle, J

    1986-01-01

    Data on raw water quality, disinfection treatment practices, and the resulting mutagenic properties of the treated water were compiled from pilot- and full-scale treatment experiments to evaluate that parameter which might produce variability in the results of a mutagenic study. Analysis of the data and comparison of treatment practices indicated that the measured mutagenic activity is strongly related to the characteristics of the organic matter in the raw water, the methodology used to sample and detect mutagens, the scale of the study both in terms of treatment flow and period of study, and the point at which and the conditions under which oxidants are added during treatment. Conclusions regarding disinfection systems in full-scale water treatment plants include the following: When raw water is pretreated and high concentrations of organics are present in the raw water, both ozonation and chlorination increased mutagenic activity. However, no significant difference in mutagenicity was found between the two oxidants. Both in the case of a nitrified groundwater and a clarified surface water, the mutagenic activity of the water after ozonation was related to its mutagenic activity before ozonation. With ozonation, mutagenic activity decreased after granular activated carbon (GAC) filtration. Thus, when GAC filtration follows ozone disinfection, early addition of oxidants may not be deleterious to the finished water quality. When chlorine or chlorine dioxide is added after GAC filtration, chlorine dioxide was found to produce a less mutagenic water than chlorine. Although these conclusions suggest means of controlling mutagenic activity during treatment, it must be stressed that the measurement of mutagenicity is a presumptive index of contamination level. PMID:3816721

  18. 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

  19. 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

  20. New Product Development. Engineering and Commerce Students Join Forces with a Corporate Sponsor.

    ERIC Educational Resources Information Center

    Audet, Josee; Pegna, Joseph

    2001-01-01

    Mechanical engineering and business student teams developed new products using a corporate sponsor's technology in a simulated business setting. Students learned about product development and venture start-up, and the sponsor gained new applications for its patented technology. (SK)

  1. Foreshock activity related to enhanced aftershock production

    NASA Astrophysics Data System (ADS)

    Marsan, D.; Helmstetter, A.; Bouchon, M.; Dublanchet, P.

    2014-10-01

    Foreshock activity sometimes precedes the occurrence of large earthquakes, but the nature of this seismicity is still debated, and whether it marks transient deformation and/or slip nucleation is still unclear. We here study at the worldwide scale how foreshock occurrence affects the postseismic phase and find a significant positive correlation between foreshock and aftershock activities: earthquakes preceded by accelerating seismicity rates produce 40% more aftershocks on average, and the length of the aftershock zone after 20 days is 20% larger. These observations cannot be reproduced by standard earthquake clustering models that predict the accelerating pattern of foreshock occurrence but not its impact on aftershock activity. This strongly suggests that slow deformation transients, possibly related to episodic creep, could initiate prior to the main shock and extend past the coseismic phase, resulting in compound ruptures that include a very long period (up to tens of days) component.

  2. 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

  3. 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

  4. '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

  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. 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

  7. 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…

  8. Using DOE-ARM and Space-Based Assets to Assess the Quality of Air Force Weather 3D Cloud Analysis and Forecast Products

    NASA Astrophysics Data System (ADS)

    Nobis, T. E.

    2015-12-01

    Air Force Weather (AFW) has documented requirements for global cloud analysis and forecasting to support DoD missions around the world. To meet these needs, AFW utilizes a number of cloud products. Cloud analyses are constructed using 17 different near real time satellite sources. Products include analysis of the individual satellite transmissions at native satellite resolution and an hourly global merge of all 17 sources on a 24km grid. AFW has also recently started creation of a time delayed global cloud reanalysis to produce a 'best possible' analysis for climatology and verification purposes. Forecasted cloud products include global short-range cloud forecasts created using advection techniques as well as statistically post processed cloud forecast products derived from various global and regional numerical weather forecast models. All of these cloud products cover different spatial and temporal resolutions and are produced on a number of different grid projections. The longer term vision of AFW is to consolidate these various approaches into uniform global numerical weather modeling (NWM) system using advanced cloudy-data assimilation processes to construct the analysis and a licensed version of UKMO's Unified Model to produce the various cloud forecast products. In preparation for this evolution in cloud modeling support, AFW has started to aggressively benchmark the performance of their current capabilities. Cloud information collected from so called 'active' sensors on the ground at the DOE-ARM sites and from space by such instruments as CloudSat, CALIPSO and CATS are being utilized to characterize the performance of AFW products derived largely by passive means. The goal is to understand the performance of the 3D cloud analysis and forecast products of today to help shape the requirements and standards for the future NWM driven system.This presentation will present selected results from these benchmarking efforts and highlight insights and observations

  9. 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.

  10. The flare productivity of active regions

    NASA Astrophysics Data System (ADS)

    Kuroda, N.; Christe, S.

    2012-12-01

    Previous studies have shown that the flare frequency distribution is consistent with a power-law. Furthermore, studies have shown that regions of higher magnetic complexity produce more large flares. This may imply that the flare frequency distribution is harder for magnetically complex active regions. However, the relationship between source active regions' magnetic complexity and the flare size distribution has not been extensively studied. We present a new study of 25,000 microflares detected by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) from March 2002 to February 2007. For each flare, we have obtained the two classifications of magnetic complexity, the Mount Wilson Magnetic Classification and the Zurich/McIntosh Sunspot Classification, from the Solar Region Summary prepared by the National Oceanic and Atmospheric Administration (NOAA)/ Space Weather Prediction Center (SWPC), and compared them with the RHESSI flare size distribution as observed in the 12 to 25 keV energy range. We investigate the relationship between the slope of the microflare size distribution and the magnetic properties of source active regions. For each flare we obtain the relevant MDI magnetogram to determine properties such as the area of the source active region and total unsigned magnetic flux. These properties are then compared to properties of the associated microflares such as peak flux and microflare size distribution. We find that, for both the Mount Wilson Magnetic Classification and the Zurich/McIntosh Sunspot Classification, the slopes of the microflare size distribution tend to get harder as a function of magnetic complexity. For example, in Mount Wilson Magnetic Classification the slope for α regions was 1.66 and the slope for βγδ region was 1.51.This suggests that βγδ regions are 50 % more likely to produce X class flares than α regions.

  11. Load-induced enhancement of Dynein force production by LIS1–NudE in vivo and in vitro

    PubMed Central

    Reddy, Babu J. N.; Mattson, Michelle; Wynne, Caitlin L.; Vadpey, Omid; Durra, Abdo; Chapman, Dail; Vallee, Richard B.; Gross, Steven P.

    2016-01-01

    Most sub-cellular cargos are transported along microtubules by kinesin and dynein molecular motors, but how transport is regulated is not well understood. It is unknown whether local control is possible, for example, by changes in specific cargo-associated motor behaviour to react to impediments. Here we discover that microtubule-associated lipid droplets (LDs) in COS1 cells respond to an optical trap with a remarkable enhancement in sustained force production. This effect is observed only for microtubule minus-end-moving LDs. It is specifically blocked by RNAi for the cytoplasmic dynein regulators LIS1 and NudE/L (Nde1/Ndel1), but not for the dynactin p150Glued subunit. It can be completely replicated using cell-free preparations of purified LDs, where duration of LD force production is more than doubled. These results identify a novel, intrinsic, cargo-associated mechanism for dynein-mediated force adaptation, which should markedly improve the ability of motor-driven cargoes to overcome subcellular obstacles. PMID:27489054

  12. Load-induced enhancement of Dynein force production by LIS1-NudE in vivo and in vitro.

    PubMed

    Reddy, Babu J N; Mattson, Michelle; Wynne, Caitlin L; Vadpey, Omid; Durra, Abdo; Chapman, Dail; Vallee, Richard B; Gross, Steven P

    2016-01-01

    Most sub-cellular cargos are transported along microtubules by kinesin and dynein molecular motors, but how transport is regulated is not well understood. It is unknown whether local control is possible, for example, by changes in specific cargo-associated motor behaviour to react to impediments. Here we discover that microtubule-associated lipid droplets (LDs) in COS1 cells respond to an optical trap with a remarkable enhancement in sustained force production. This effect is observed only for microtubule minus-end-moving LDs. It is specifically blocked by RNAi for the cytoplasmic dynein regulators LIS1 and NudE/L (Nde1/Ndel1), but not for the dynactin p150(Glued) subunit. It can be completely replicated using cell-free preparations of purified LDs, where duration of LD force production is more than doubled. These results identify a novel, intrinsic, cargo-associated mechanism for dynein-mediated force adaptation, which should markedly improve the ability of motor-driven cargoes to overcome subcellular obstacles. PMID:27489054

  13. 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

  14. Phosphorylation of a twitchin-related protein controls catch and calcium sensitivity of force production in invertebrate smooth muscle

    PubMed Central

    Siegman, Marion J.; Funabara, Daisuke; Kinoshita, Shigeharu; Watabe, Shugo; Hartshorne, David J.; Butler, Thomas M.

    1998-01-01

    “Catch” is a condition of prolonged, high-force maintenance at resting intracellular Ca2+ concentration ([Ca2+]) and very low energy usage, occurring in invertebrate smooth muscles, including the anterior byssus retractor muscle (ABRM) of Mytilus edulis. Relaxation from catch is rapid on serotonergic nerve stimulation in intact muscles and application of cAMP in permeabilized muscles. This release of catch occurs by protein kinase A-mediated phosphorylation of a high (≈600 kDa) molecular mass protein, the regulator of catch. Here, we identify the catch-regulating protein as a homologue of the mini-titin, twitchin, based on (i) a partial cDNA of the purified isolated protein showing 77% amino acid sequence identity to the kinase domain of Aplysia californica twitchin; (ii) a polyclonal antibody to a synthetic peptide in this sequence reacting with the phosphorylated catch-regulating protein band from permeabilized ABRM; and (iii) the similarity of the amino acid composition and molecular weight of the protein to twitchin. In permeabilized ABRM, at all but maximum [Ca2+], phosphorylation of twitchin results in a decreased calcium sensitivity of force production (half-maximum at 2.5 vs. 1.3 μM calcium). At a given submaximal force, with equal numbers of force generators, twitchin phosphorylation increased unloaded shortening velocity ≈2-fold. These data suggest that aspects of the catch state exist not only at resting [Ca2+], but also at higher submaximal [Ca2+]. The mechanism that gives rise to force maintenance in catch probably operates together, to some extent, with that of cycling myosin crossbridges. PMID:9560285

  15. 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

  16. 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

  17. 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

  18. 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.

  19. A unique micromechanocalorimeter for simultaneous measurement of heat rate and force production of cardiac trabeculae carneae.

    PubMed

    Han, June-Chiew; Taberner, Andrew J; Kirton, Robert S; Nielsen, Poul M; Smith, Nicholas P; Loiselle, Denis S

    2009-09-01

    To study cardiac muscle energetics quantitatively, it is of paramount importance to measure, simultaneously, mechanical and thermal performance. Ideally, this should be achieved under conditions that minimize the risk of tissue anoxia, especially under high rates of energy expenditure. In vitro, this consideration necessitates the use of preparations of small radial dimensions. To that end, we have constructed a unique micromechanocalorimeter, consisting of an open-ended flow-through microcalorimeter, a force transducer, and a pair of muscle-length actuators. The device enables the metabolic and mechanical performance of cardiac trabeculae carneae to be investigated for prolonged periods in a continuously replenished oxygen- and nutrient-rich environment. PMID:19589958

  20. RBSE: Product development team research activity deliverables

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The GHG Functions and Extensions to be added to the NASA Electronic Library System (NELS) 1.1 product are described. These functions will implement the 'output request' capability within the Object Browser. The functions will be implemented in two parts. The first part is a code to be added to the Object Browser (X version) to implement menus allowing the user to request that objects be copied to specific media, or that objects be downloaded to the user's system following a specific protocol, or that the object be printed to one of the printers attached to the host system. The second part is shell scripts which support the various menu selections. Additional scripts to support functions within the GHG shell (X version) will also be created along with the X version of the GHG Shell as initial capability for the 27 Mar. prototype. The scripts will be composed of C shell routines that will accept parameters (primary file pathways). Certain limitations in functionality will invoke Mail instead of Oracle Mail since that has yet to be delivered and the NELS invocation will default to the X-Windows version instead of the ASCII version.

  1. 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

  2. Incidence and recent trends in functional gastrointestinal disorders, active component, U.S. Armed Forces, 2005-2014.

    PubMed

    Johnson, Amelia G; Hu, Zheng; Cost, Angelia A

    2016-06-01

    Functional gastrointestinal disorders (FGIDs) are common chronic conditions with an unknown pathophysiology and etiology. FGIDs elevate healthcare costs and cause substantial burden to public health and the military, including diminished readiness, productivity, and quality of life. This retrospective cohort study of active component U.S. military personnel covered a 10-year surveillance period, 2005-2014. The Defense Medical Surveillance System (DMSS) was the data source. Incident cases were identified and rates were calculated and stratified by important covariates. Trends were described over the surveillance period. Incidence rates among deployed personnel were compared to rates in non-deployed personnel, stratified by age and sex. An increasing trend in functional constipation was observed during 2005-2012. Being female, black, in the Army or Air Force, and younger than 20 years of age or 40 years of age or older was associated with higher incidence rates. Deployment-exposed personnel had incidence rates that were 53% higher than those of non-deployed personnel. Elevated rates in personnel younger than 20 years of age and deployed personnel evoke interest concerning readiness and cost implications for the Military Health System. These subgroups should be examined in future studies. PMID:27362344

  3. 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.

  4. Force generation and work production by covalently cross-linked actin-myosin cross-bridges in rabbit muscle fibers.

    PubMed

    Bershitsky, S Y; Tsaturyan, A K

    1995-09-01

    To separate a fraction of the myosin cross-bridges that are attached to the thin filaments and that participate in the mechanical responses, muscle fibers were cross-linked with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and then immersed in high-salt relaxing solution (HSRS) of 0.6 M ionic strength for detaching the unlinked myosin heads. The mechanical properties and force-generating ability of the cross-linked cross-bridges were tested with step length changes (L-steps) and temperature jumps (T-jumps) from 6-10 degrees C to 30-40 degrees C. After partial cross-linking, when instantaneous stiffness in HSRS was 25-40% of that in rigor, the mechanical behavior of the fibers was similar to that during active contraction. The kinetics of the T-jump-induced tension transients as well as the rate of the fast phase of tension recovery after length steps were close to those in unlinked fibers during activation. Under feedback force control, the T-jump initiated fiber shortening by up to 4 nm/half-sarcomere. Work produced by a cross-linked myosin head after the T-jump was up to 30 x 10(-21) J. When the extent of cross-linking was increased and fiber stiffness in HSRS approached that in rigor, the fibers lost their viscoelastic properties and ability to generate force with a rise in temperature. PMID:8519956

  5. A drag-based mechanism for vertical force production in the smallest flying insects

    NASA Astrophysics Data System (ADS)

    Jones, Shannon; Laurenza, Ryan; Miller, Laura

    2013-11-01

    Previous work has shown that the flight kinematics and aerodynamics of the smallest flying insects may be significantly different than that of their larger counterparts. These small insects, such as thrips and parasitoid wasps, are on the order of 1 mm in length and operate at a Reynolds number less than 10. Due to their small size and high wing beat frequency, quantitative data on the wing kinematics of the smallest insects is not available. As a result, there has been much debate and speculation about the flight strategies employed by these insects. With the challenges associated with generating lift at low Reynolds numbers, it could be beneficial for the smallest insects to use a drag-based motion to generate some or all of its vertical force, however this has not been rigorously investigated. We used computational fluid dynamics to investigate the feasibility of drag-based propulsion in the tiniest insects. We investigated the vertical force generated by an idealized drag-based vertical stroke over a range of Reynolds numbers from 1 to 150. We also compared this stroke to more conventional hovering stroke kinematics such as that of a fruit fly and dragonfly.

  6. The Characteristics of Force Production of Kinesin-5 on MCF7 Microtubules

    NASA Astrophysics Data System (ADS)

    Shojania Feizabadi, Mitra

    Unlike neural mammalian microtubules with class II of beta tubulin as the major beta tubulin in their compositions, MCF7 microtubules composed of 0% class II beta tubulin isotype, 39.1% class I beta tubulin isotype, 2.5% class III beta tubulin isotype and 58.4% class IV beta tubulin isotype. Recent studies have revealed that function of some of motor proteins can be affected by the structural composition of microtubules. In this work, we will show how the function of mitotic kinesin (Kin-5) under external load changed when moving along bovine versus MCF7 microtubules. Along MCF7 microtubules, the detachment force was reduced and the force-velocity curve was different as compared to those related to bovine brain. We will also show that the elimination of the C-terminal tails made the transport almost similar to the two sets of microtubules. This suggests that the C-terminal tails of tubulin plays a regulatory role in Kinesin-5's function.

  7. 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

  8. 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

  9. Activities of the Oil Implementation Task Force, December 1990--February 1991; Contracts for field projects and supporting research on enhanced oil recovery, April--June 1990

    SciTech Connect

    Tiedemann, H.A. )

    1991-03-01

    The Oil Implementation Task Force was appointed to implement the US DOE's new oil research program directed toward increasing domestic oil production by expanded research on near- or mid-term enhanced oil recovery methods. An added priority is to preserve access to reservoirs that have the largest potential for oil recovery, but that are threatened by the large number of wells abandoned each year. This report describes the progress of research activities in the following areas: chemical flooding; gas displacement; thermal recovery; resource assessment; microbial technology; geoscience technology; and environmental technology. (CK)

  10. Isocoumarins, miraculous natural products blessed with diverse pharmacological activities.

    PubMed

    Saeed, Aamer

    2016-06-30

    Isocoumarins are lactonic natural products abundant in microbes and higher plants. These are considered an amazing scaffold consecrated with more or less all types of pharmacological applications. This review is complementary to the earlier reviews and aims to focus the overlooked aspects of their fascinating chemistry with special emphasis on their classification and diverse biological activities with some SAR conclusions. The most recent available literature on the structural diversity and biological activity of these natural products has been reviewed. PMID:27155563

  11. 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…

  12. 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…

  13. EDI Data Products in the Cluster Active Archive

    NASA Astrophysics Data System (ADS)

    Georgescu, E.; Puhl-Quinn, P.; Vaith, H.; Chutter, M.; Quinn, J.; Paschmann, G.; Torbert, R.

    The Electron Drift Instrument (EDI) contribution to the Cluster Active Archive (CAA) is described. Presented are descriptions of the EDI instrument, the various CAA/EDI data products, the CAA ingestion schedule and the current EDI status. An example of a science application is given for one of the main EDI data products available in the CAA.

  14. 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.

  15. 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

  16. Mechanism driven structural elucidation of forced degradation products from hydrocortisone in solution.

    PubMed

    Zhang, Fa; Zhou, Jay; Shi, Yiqun; Tavlarakis, Panagiotis; Karaisz, Kenneth

    2016-09-01

    Hydrocortisone degradation products 1, 2, 3, and 4 along with hemiacetal derivatives 5, 6, 7, and 8 were observed through stressed hydrocortisone in solution. Their structures were identified based on HPLC-UV, HPLC-MS, and HPLC-HRMS (high resolution/high accuracy mass spectrometry) analyses as well as reaction mechanistic investigation and synthesis for structural confirmation. 1 and 2 are a pair of E/Z isomers and they were generated through acid catalyzed tautomerization/dehydration of hydrocortisone. Incorporation of water to 1 and 2 resulted in the formation of 3. We also discovered new degradation product 4 which was converted from 3 by oxidation. The degradation products were synthesized by stressing hydrocortisone under the optimized conditions and their structures were characterized by NMR ((1)H/(13)C, COSY, HMBC, HSQC, NOESY) and HRMS analyses. The degradation pathway of hydrocortisone is postulated. PMID:27328360

  17. 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.

  18. 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.

  19. Influence of product phase separation on phospholipase A(2) hydrolysis of supported phospholipid bilayers studied by force microscopy.

    PubMed Central

    Nielsen, Lars K; Balashev, Konstatin; Callisen, Thomas H; Bjørnholm, Thomas

    2002-01-01

    In situ atomic force microscopy studies reveal a marked influence of the initial presence of hydrolysis products on the hydrolysis of supported phospholipid bilayers by phospholipase A(2). By analysis of the nano-scale topography of a number of supported bilayers with different initial product concentrations, made by Langmuir-Blodgett deposition, we show that small depressions enriched in products are efficiently promoting enzyme degradation of the bilayer. These small depressions, which are indicative of phase separation, are initially present in samples with 75% products. The kinetics of phospholipase A(2) exhibit under certain conditions an initial phase of slow hydrolysis, termed the latency phase, followed by a marked increase in the hydrolysis rate. The appearance of the phase-separated bilayer is strikingly similar to that of bilayers at the end of the latency phase. By analysis of individual nano-scale defects we illustrate a quantitative difference in the growth rates of defects caused by product aggregation and other structural defects. This difference shows for the first time how the enzyme prefers one type of defect to another. PMID:12414695

  20. 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

  1. 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.

  2. [Cytogenetic activity of the butylcaptax defoliant transformation product].

    PubMed

    Vesmanova, O Ia; Semykina, E E; Koblov, R K; Ergashev

    1989-01-01

    Cytogenetical activity of the product of metabolitic butylcaptax transformations in cells of cotton plants G. barbadense has been studied. It is shown that butylcaptax, with a significant mutagenicity, looses its mutagenic activity, metabolizing in low mutagenic 2-oxyamylthiobenzthiazole. Low water solubility prevents its concentration to exceed 0.005% in tissue liquids and to exert a mutagenic action on cotton plants. PMID:2773061

  3. Itawamba Community College and Tecumseh Products Company, Inc.: A High Performance Work Force Development Partnership.

    ERIC Educational Resources Information Center

    Itawamba Community Coll., Tupelo, MS.

    Since 1976, Mississippi's Itawamba Community College (ICC) and Tecumseh Products Company (TPC) have maintained a cooperative relationship providing the firm with support and services stemming from ICC's Skill/Tech One-Stop Career Center. The support offered to TPC has included the following: (1) since 1976, 105 pre-employment classes have been…

  4. LC-MS/MS characterization of forced degradation products of zofenopril.

    PubMed

    Ramesh, Thippani; Nageswara Rao, Pothuraju; Nageswara Rao, Ramisetti

    2014-01-01

    A rapid, specific and reliable isocratic LC-MS/MS method has been developed and validated for the identification and characterization of stressed degradation products of Zofenopril. Zofenopril, an anti-hypertensive drug, was subjected to hydrolysis (acidic, alkaline and neutral), oxidation, photolysis and thermal stress, as per ICH-specified conditions. The drug showed extensive degradation under oxidative and base hydrolysis stress conditions. However, it was stable to thermal, acid, neutral and photolysis stress conditions. A total of 6 degradation products were observed and the chromatographic separation of the drug and its degradation products were achieved on Phenomenex (Luna) C18 (250mm×4.6mm, i.d., 5μm) column using 20mM ammonium acetate: acetonitrile (50:50, v/v) as a mobile phase. The degradation products were characterized by LC-MS/MS and its fragmentation pathways were proposed. The LC-MS method was validated with respect to specificity, linearity, accuracy and precision. No previous reports were found in the literature regarding the degradation behavior of zofenopril. PMID:24211724

  5. Assessment of activation products in the Savannah River Site environment

    SciTech Connect

    Carlton, W.H.; Denham, M.

    1996-07-01

    This document assesses the impact of radioactive activation products released from SRS facilities since the first reactor became operational late in 1953. The isotopes reported here are those whose release resulted in the highest dose to people living near SRS: {sup 32}P, {sup 51}Cr, {sup 60}C, and {sup 65}Zn. Release pathways, emission control features, and annual releases to the aqueous and atmospheric environments are discussed. No single incident has resulted in a major acute release of activation products to the environment. The releases were the result of normal operations of the reactors and separations facilities. Releases declined over the years as better controls were established and production was reduced. The overall radiological impact of SRS activation product atmospheric releases from 1954 through 1994 on the offsite maximally exposed individual can be characterized by a total dose of 0.76 mrem. During the same period, such an individual received a total dose of 14,400 mrem from non-SRS sources of ionizing radiation present in the environment. SRS activation product aqueous releases between 1954 and 1994 resulted in a total dose of 54 mrem to the offsite maximally exposed individual. The impact of SRS activation product releases on offsite populations also has been evaluated.

  6. Low-level intermittent quadriceps activity during transcranial direct current stimulation facilitates knee extensor force-generating capacity.

    PubMed

    Washabaugh, Edward P; Santos, Luciana; Claflin, Edward S; Krishnan, Chandramouli

    2016-08-01

    Anodal transcranial direct current stimulation (tDCS) is known to increase the force-generating capacity of the skeletal muscles. However, when tDCS is concurrently combined with a motor task, interference may occur that hinders tDCS effects. Here, we tested the interaction and time course of tDCS effects on force production when paired with a low-level force-matching task. Twenty-two subjects were randomized into two groups: tDCS-Matching and tDCS-Resting. Each group received tDCS and a sham stimulation, separated by one week. Maximal knee extensor and flexor torques were measured before and up to twenty-five minutes following the stimulation. The tDCS-Matching group produced greater knee extension torques relative to sham when compared with the tDCS-Resting group. There was no significant effect for knee flexion. This suggests that interference does not occur for force production tasks when tDCS is combined with a motor task. Rather, the task appears to aid and isolate the effects to the muscle groups involved in the task. PMID:27138643

  7. Milk kefir: composition, microbial cultures, biological activities, and related products

    PubMed Central

    Prado, Maria R.; Blandón, Lina Marcela; Vandenberghe, Luciana P. S.; Rodrigues, Cristine; Castro, Guillermo R.; Thomaz-Soccol, Vanete; Soccol, Carlos R.

    2015-01-01

    In recent years, there has been a strong focus on beneficial foods with probiotic microorganisms and functional organic substances. In this context, there is an increasing interest in the commercial use of kefir, since it can be marketed as a natural beverage that has health promoting bacteria. There are numerous commercially available kefir based-products. Kefir may act as a matrix in the effective delivery of probiotic microorganisms in different types of products. Also, the presence of kefir’s exopolysaccharides, known as kefiran, which has biological activity, certainly adds value to products. Kefiran can also be used separately in other food products and as a coating film for various food and pharmaceutical products. This article aims to update the information about kefir and its microbiological composition, biological activity of the kefir’s microflora and the importance of kefiran as a beneficial health substance. PMID:26579086

  8. 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

  9. 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

  10. UV microbeam irradiations of the mitotic spindle. II. Spindle fiber dynamics and force production

    SciTech Connect

    Spurck, T.P.; Stonington, O.G.; Snyder, J.A.; Pickett-Heaps, J.D.; Bajer, A.; Mole-Bajer, J. )

    1990-10-01

    Metaphase and anaphase spindles in cultured newt and PtK1 cells were irradiated with a UV microbeam (285 nM), creating areas of reduced birefringence (ARBs) in 3 s that selectively either severed a few fibers or cut across the half spindle. In either case, the birefringence at the polewards edge of the ARB rapidly faded polewards, while it remained fairly constant at the other, kinetochore edge. Shorter astral fibers, however, remained present in the enlarged ARB; presumably these had not been cut by the irradiation. After this enlargement of the ARB, metaphase spindles recovered rapidly as the detached pole moved back towards the chromosomes, reestablishing spindle fibers as the ARB closed; this happened when the ARB cut a few fibers or across the entire half spindle. We never detected elongation of the cut kinetochore fibers. Rather, astral fibers growing from the pole appeared to bridge and then close the ARB, just before the movement of the pole toward the chromosomes. When a second irradiation was directed into the closing ARB, the polewards movement again stopped before it restarted. In all metaphase cells, once the pole had reestablished connection with the chromosomes, the unirradiated half spindle then also shortened to create a smaller symmetrical spindle capable of normal anaphase later. Anaphase cells did not recover this way; the severed pole remained detached but the chromosomes continued a modified form of movement, clumping into a telophase-like group. The results are discussed in terms of controls operating on spindle microtubule stability and mechanisms of mitotic force generation.

  11. Charged fusion product loss measurements using nuclear activation.

    PubMed

    Bonheure, G; Hult, M; González de Orduña, R; Arnold, D; Dombrowski, H; Laubenstein, M; Wieslander, E; Vermaercke, P; Murari, A; Popovichev, S; Mlynar, J

    2010-10-01

    In ITER, α particle loss measurements will be required in order to understand the alpha particle physics. Techniques capable of operating in a fusion reactor environment need further development. Recent experimental studies on JET demonstrated the potential of nuclear activation to measure the flux of escaping MeV ions. New results from MeV ion induced activation of metallic, ceramic, and crystal samples placed near the plasma edge are reported. Activation products were measured as function of orientation with respect to the magnetic field as well as function of the distance to the plasma. Sample activity was measured using ultralow-level gamma-ray spectrometry. Distribution of 14.68 MeV fusion proton induced activation products is strongly anisotropic in agreement with simulations and falls off sharply with increasing distance to the plasma. Prospects for using the technique in ITER are discussed. PMID:21058458

  12. Does living and working in a hot environment induce clinically relevant changes in immune function and voluntary force production capacity?

    PubMed

    Knez, Wade; Girard, Olivier; Racinais, Sebastien; Walsh, Andrew; Gaoua, Nadia; Grantham, Justin

    2014-01-01

    This study investigated the effect of living (summer vs. winter) and working (morning vs. afternoon) in a hot environment on markers of immune function and forearm strength. Thirty-one healthy male gas field employees were screened before (between 05:30 and 07:00) and after their working day (between 15:30 and 17:00) during both seasons. Body core temperature and physical activity were recorded throughout the working days. The hot condition (i.e. summer) led a higher (p≤0.05) average body core temperature (~37.2 vs. ~37.4 °C) but reduced physical activity (-14.8%) during the work-shift. Our data showed an increase (p≤0.05) in lymphocyte and monocyte counts in the summer. Additionally, work-shift resulted in significant (p≤0.001) changes in leukocytes, lymphocytes and monocytes independently of the environment. Handgrip (p=0.069) and pinch (p=0.077) forces tended to be reduced from pre-to post-work, while only force produced during handgrip manoeuvres was significantly reduced (p≤0.05) during the hot compared to the temperate season. No interactions were observed between the environment and work-shift for any marker of immune function or forearm strength. In summary, working and living in hot conditions impact on markers of immune function and work capacity; however by self-regulating energy expenditure, immune markers remained in a healthy reference range. PMID:24583514

  13. Enriching step-based product information models to support product life-cycle activities

    NASA Astrophysics Data System (ADS)

    Sarigecili, Mehmet Ilteris

    The representation and management of product information in its life-cycle requires standardized data exchange protocols. Standard for Exchange of Product Model Data (STEP) is such a standard that has been used widely by the industries. Even though STEP-based product models are well defined and syntactically correct, populating product data according to these models is not easy because they are too big and disorganized. Data exchange specifications (DEXs) and templates provide re-organized information models required in data exchange of specific activities for various businesses. DEXs show us it would be possible to organize STEP-based product models in order to support different engineering activities at various stages of product life-cycle. In this study, STEP-based models are enriched and organized to support two engineering activities: materials information declaration and tolerance analysis. Due to new environmental regulations, the substance and materials information in products have to be screened closely by manufacturing industries. This requires a fast, unambiguous and complete product information exchange between the members of a supply chain. Tolerance analysis activity, on the other hand, is used to verify the functional requirements of an assembly considering the worst case (i.e., maximum and minimum) conditions for the part/assembly dimensions. Another issue with STEP-based product models is that the semantics of product data are represented implicitly. Hence, it is difficult to interpret the semantics of data for different product life-cycle phases for various application domains. OntoSTEP, developed at NIST, provides semantically enriched product models in OWL. In this thesis, we would like to present how to interpret the GD & T specifications in STEP for tolerance analysis by utilizing OntoSTEP.

  14. Novel condensation products having high activity to insolubilize proteins and protein-insolubilized products

    SciTech Connect

    Krasnobajew, V.; Boeniger, R.

    1980-01-01

    According to the invention a substantially more active product with respect to the fixing or insolubilization pf proteins, including enzymes, is obtained when 1,3 phenylenediamine is condensed with glutardialdehyde. One application of the process is the enzymatic hydrolysis of lactose in milk products by lactase.

  15. 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

  16. Maximal Voluntary Static Force Production Characteristics of Skeletal Muscle in Children 8-11 Years of Age.

    ERIC Educational Resources Information Center

    Going, Scott B.; And Others

    1987-01-01

    A study of maximal voluntary isometric muscle contraction force-time curves among 32 normal, healthy 8- to 11-year-olds performing tasks involving separate muscle groups found that force and maximal rate of force increase were quite reproducible, but time to selected force levels reflected considerable variations. (Author/CB)

  17. 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

  18. Review of the anticancer activities of bee products

    PubMed Central

    Premratanachai, Pongsathon; Chanchao, Chanpen

    2014-01-01

    Bee products have long been used in traditional medicine. The raw materials, crude extracts and purified active compounds from them have been found to exhibit interesting bioactivities, such as antimicrobial, anti-inflammatory and antioxidant activities. In addition, they have been widely used in the treatment of many immune-related diseases, as well as in recent times in the treatment of tumors. Bee product peptides induce apoptotic cell death in vitro in several transformed (cancer) human cell lines, including those derived from renal, lung, liver, prostate, bladder and lymphoid cancers. These bioactive natural products may, therefore, prove to be useful as part of a novel targeted therapy for some types of cancer, such as prostate and breast cancer. This review summarizes the current knowledge regarding the in vivo and in vitro potential of selective bee products against tumor cells. PMID:25182716

  19. Effects of aft geometry on vortex behavior and force production by a tangential jet on a body at high alpha

    NASA Technical Reports Server (NTRS)

    Font, G. I.

    1993-01-01

    Explored in this study are the physical effects of the numerical treatment of the aft geometry on the vortex behavior and force production due to a tangential jet on a body at a high angle of attack. The study is conducted numerically by solving the three-dimensional, compressible-flow, Reynolds-averaged Navier-Stokes equations. Two tangent-ogive cylinder configurations are used. The first configuration locates the computational exit plane at the end of the body, while the second caps the end of the body with a hemisphere and locates the exit plane far downstream. In both configurations, a blowing slot is located at the cylinder-ogive junction. Comparisons are made between results for the two configurations for cases with and without the jet present. Results indicate that inclusion of the wake of the body in the computations, while altering the flow in small details, does not change the character of the flow. The vortex behavior remains unaltered and the force distribution, while changing to some degree in magnitude, does not change in shape.

  20. 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.

  1. 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;…

  2. Forced Degradation Behaviour of Fluphenazine Hydrochloride by LC and Characterization of its Oxidative Degradation Product by LC–MS/MS

    PubMed Central

    Thummar, Kashyap N.; Ghava, Dilip J.; Mistry, Anvi; Vachhani, Ashish; Sheth, Navin R.

    2015-01-01

    A novel, stability-indicating high-performance liquid chromatographic (HPLC) method is delivered for the determination of fluphenazine hydrochloride (FPZ) and its degradation products. The forced degradation testing of FPZ was carried out for hydrolytic, oxidative, photolytic, and thermal degradation. The degradation appeared using a reversed-phase C18 column at ambient temperature with a mobile phase comprised of methanol : acetonitrile : (10 mM) ammonium acetate (70:15:15, v/v/v) pH 6.0, adjusted with acetic acid, having a flow rate of 1 ml min−1 and a detection wavelength at 259 nm. Primarily, the maximum degradation products were formed under oxidative stress conditions. The product was distinguished through LC-MS/MS fragmentation studies. Based on the results, a more complete degradation pathway for the drug could be proposed. The modernized method was found to be precise, accurate, specific, and selective. The method was found to be suitable for the quality control of fluphenazine hydrochloride in the tablet as well as in stability-indicating studies. PMID:26839816

  3. Forced Degradation Behaviour of Fluphenazine Hydrochloride by LC and Characterization of its Oxidative Degradation Product by LC-MS/MS.

    PubMed

    Thummar, Kashyap N; Ghava, Dilip J; Mistry, Anvi; Vachhani, Ashish; Sheth, Navin R

    2015-01-01

    A novel, stability-indicating high-performance liquid chromatographic (HPLC) method is delivered for the determination of fluphenazine hydrochloride (FPZ) and its degradation products. The forced degradation testing of FPZ was carried out for hydrolytic, oxidative, photolytic, and thermal degradation. The degradation appeared using a reversed-phase C18 column at ambient temperature with a mobile phase comprised of methanol : acetonitrile : (10 mM) ammonium acetate (70:15:15, v/v/v) pH 6.0, adjusted with acetic acid, having a flow rate of 1 ml min(-1) and a detection wavelength at 259 nm. Primarily, the maximum degradation products were formed under oxidative stress conditions. The product was distinguished through LC-MS/MS fragmentation studies. Based on the results, a more complete degradation pathway for the drug could be proposed. The modernized method was found to be precise, accurate, specific, and selective. The method was found to be suitable for the quality control of fluphenazine hydrochloride in the tablet as well as in stability-indicating studies. PMID:26839816

  4. [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

  5. 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.

  6. 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

  7. 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

  8. Polyhydroxyalkanoate production potential of heterotrophic bacteria in activated sludge.

    PubMed

    Inoue, Daisuke; Suzuki, Yuta; Uchida, Takahiro; Morohoshi, Jota; Sei, Kazunari

    2016-01-01

    This study was conducted to evaluate the polyhydroxyalkanoate (PHA) production potential of cultivable heterotrophic bacteria in activated sludge by genotypic and phenotypic characterizations. A total of 114 bacterial strains were isolated from four activated sludge samples taken from a lab-scale sequencing batch reactor and three wastewater treatment processes of two municipal wastewater treatment plants. PCR detection of the phaC genes encoding class I and II PHA synthase revealed that 15% of the total isolates possessed phaC genes, all of which had the closest similarities to known phaC genes of α- and β-Proteobacteria and Actinobacteria. PHA production experiments under aerobic and nitrogen-limited conditions showed that 68% of the total isolates were capable of producing PHA from at least one of the six substrates used (acetate, propionate, lactate, butyrate, glucose and glycerol). Genotypic and phenotypic characterizations revealed that 75% of the activated sludge bacteria had PHA production potential. Our results also indicated that short-chain fatty acids would be the preferable substrates for PHA production by activated sludge bacteria, and that there might be a variety of unidentified phaC genes in activated sludge. PMID:26071670

  9. Antioxidant activity of honey supplemented with bee products.

    PubMed

    Juszczak, Lesław; Gałkowska, Dorota; Ostrowska, Małgorzata; Socha, Robert

    2016-06-01

    The aim of this work was to evaluate the influence of supplementation of multiflower honey with bee products on the phenolic compound content and on antioxidant activity. Average total phenolic and flavonoids contents in the multiflower honeys were 36.06 ± 10.18 mg GAE/100 g and 4.48 ± 1.69 mg QE/100 g, respectively. The addition of royal jelly did not affect significantly the phenolic compound content and antioxidant activity. Supplementation of honey with other bee products, i.e. beebread, propolis, pollen, resulted in significant increase in the total phenolic and flavonoids contents, and in antiradical activity and reducing power, with the largest effect found for addition of beebread. Significant linear correlations between the total phenolic and flavonoids contents and antiradical activity and reducing power were found. PMID:26153086

  10. The integrin-adhesome is required to maintain muscle structure, mitochondrial ATP production, and movement forces in Caenorhabditis elegans

    PubMed Central

    Etheridge, Timothy; Rahman, Mizanur; Gaffney, Christopher J.; Shaw, Debra; Shephard, Freya; Magudia, Jignesh; Solomon, Deepak E.; Milne, Thomas; Blawzdziewicz, Jerzy; Constantin-Teodosiu, Dumitru; Greenhaff, Paul L.; Vanapalli, Siva A.; Szewczyk, Nathaniel J.

    2015-01-01

    The integrin-adhesome network, which contains >150 proteins, is mechano-transducing and located at discreet positions along the cell-cell and cell-extracellular matrix interface. A small subset of the integrin-adhesome is known to maintain normal muscle morphology. However, the importance of the entire adhesome for muscle structure and function is unknown. We used RNA interference to knock down 113 putative Caenorhabditis elegans homologs constituting most of the mammalian adhesome and 48 proteins known to localize to attachment sites in C. elegans muscle. In both cases, we found >90% of components were required for normal muscle mitochondrial structure and/or proteostasis vs. empty vector controls. Approximately half of these, mainly proteins that physically interact with each other, were also required for normal sarcomere and/or adhesome structure. Next we confirmed that the dystrophy observed in adhesome mutants associates with impaired maximal mitochondrial ATP production (P < 0.01), as well as reduced probability distribution of muscle movement forces compared with wild-type animals. Our results show that the integrin-adhesome network as a whole is required for maintaining both muscle structure and function and extend the current understanding of the full complexities of the functional adhesome in vivo.—Etheridge, T., Rahman, M., Gaffney, C. J., Shaw, D., Shephard, F., Magudia, J., Solomon, D. E., Milne, T., Blawzdziewicz, J., Constantin-Teodosiu, D., Greenhaff, P. L., Vanapalli, S. A., Szewczyk, N. J. The integrin-adhesome is required to maintain muscle structure, mitochondrial ATP production, and movement forces in Caenorhabditis elegans. PMID:25491313

  11. Long-lived activation products in reactor materials

    SciTech Connect

    Evans, J.C.; Lepel, E.L.; Sanders, R.W.; Wilkerson, C.L.; Silker, W.; Thomas, C.W.; Abel, K.H.; Robertson, D.R.

    1984-08-01

    The purpose of this program was to assess the problems posed to reactor decommissioning by long-lived activation products in reactor construction materials. Samples of stainless steel, vessel steel, concrete, and concrete ingredients were analyzed for up to 52 elements in order to develop a data base of activatable major, minor, and trace elements. Large compositional variations were noted for some elements. Cobalt and niobium concentrations in stainless steel, for example, were found to vary by more than an order of magnitude. A thorough evaluation was made of all possible nuclear reactions that could lead to long lived activation products. It was concluded that all major activation products have been satisfactorily accounted for in decommissioning planning studies completed to date. A detailed series of calculations was carried out using average values of the measured compositions of the appropriate materials to predict the levels of activation products expected in reactor internals, vessel walls, and bioshield materials for PWR and BWR geometries. A comparison is made between calculated activation levels and regulatory guidelines for shallow land disposal according to 10 CFR 61. This analysis shows that PWR and BWR shroud material exceeds the Class C limits and is, therefore, generally unsuitable for near-surface disposal. The PWR core barrel material approaches the Class C limits. Most of the remaining massive components qualify as either Class A or B waste with the bioshield clearly Class A, even at the highest point of activation. Selected samples of activated steel and concrete were subjected to a limited radiochemical analysis program as a verification of the computer model. Reasonably good agreement with the calculations was obtained where comparison was possible. In particular, the presence of /sup 94/Nb in activated stainless steel at or somewhat above expected levels was confirmed.

  12. Moisture and Climatic Forcings on Sphagnum Productivity in a Cutover Peatland

    NASA Astrophysics Data System (ADS)

    Thompson, D. K.; Waddington, J. M.

    2007-12-01

    Gross ecosystem production (GEP) was measured at a sub-boreal ombotrophic peatland (Cacouna Bog) 15 km NE of Riviere-du-Loup, Quebec, in the summers of 2005 and 2006. The Cacouna bog was extensively mined between 1940 and 1970 using the block cut method. The combination of exposed, high bulk density peat and low water table (c. 30 cm) has produced a succession vegetation community of ericaceous shrubs, invasive trees, and only c. 10% Sphagnum moss cover. Chamber-based measurements were made at three locations arranged longitudinally along a cut trench. Volumetric water content (VWC) and temperature probes at four depths, tensiometers, and a meteorological station provided high temporal resolution moisture and climatic data. June to August precipitation in 2005 was 167 mm below the 30-year mean; in 2006, the deviation was only 17 mm below normal. The cool and dry summer of 2005 depressed VWC by 10-20 %, soil water tension by 20-40 mb, and maximum GEP by 5-10 g C m-2 d-1 as compared to 2006. Instantaneous GEP did not decline during prolonged rain-free periods in August 2005 where soil tensions exceeded -100 mb, within the hypothetical range of hyaline cell drainage and reduced GEP. The response of these Sphagnum cushions points to a resilience to hydrologic stress at intermediate age (35 years since establishment) not otherwise observed in younger Sphagnum cushions less than 5 years since establishment. These findings have implications on the parameterization of sensitivity to moisture stress in bog growth models, and to management of restored and naturally regenerating peatlands.

  13. Interplay of drought and tropical cyclone activity in SE U.S. gross primary productivity

    NASA Astrophysics Data System (ADS)

    Lowman, Lauren E. L.; Barros, Ana P.

    2016-06-01

    Tropical cyclones (TCs), often associated with massive flooding and landslides in the Southeast U.S. (SE U.S.), provide a significant input of freshwater to the hydrologic system, and their timing and trajectory significantly impact drought severity and persistence. This manuscript investigates the sensitivity of gross primary productivity (GPP) in the SE U.S. to TC activity using the 1-D column implementation of the Duke Coupled Hydrology Model with Vegetation (DCHM-V) including coupled water and energy cycles and a biochemical representation of photosynthesis. Decadal-scale simulations of water, energy, and carbon fluxes were conducted at high temporal (30 min) and spatial (4 km) resolution over the period 2002-2012. At local scales, model results without calibration compare well against AmeriFlux tower data. At regional scales, differences between the DCHM-V estimates and the Moderate Resolution Imaging Spectroradiometer GPP product reflect the spatial organization of soil hydraulic properties and soil moisture dynamics by physiographic region, highlighting the links between the water and carbon cycles. To isolate the contribution of TC precipitation to SE U.S. productivity, control forcing simulations are contrasted with simulations where periods of TC activity in the atmospheric forcing data were replaced with climatology. During wet years, TC activity impacts productivity in 40-50% of the SE U.S. domain and explains a regional GPP increase of 3-5 Mg C/m2 that is 9% of the warm season total. In dry years, 23-34% of the domain exhibits a smaller positive response that corresponds to 4-8% of the seasonal carbon uptake, depending on TC timing and trajectory.

  14. Review: Production and functionality of active peptides from milk.

    PubMed

    Muro Urista, C; Álvarez Fernández, R; Riera Rodriguez, F; Arana Cuenca, A; Téllez Jurado, A

    2011-08-01

    In recent years, research on the production of active peptides obtained from milk and their potential functionality has grown, to a great extent. Bioactive peptides have been defined as specific protein fragments that have a positive impact on body functions or conditions, and they may ultimately have an influence on health. Individual proteins of casein or milk-derived products such as cheese and yogurt have been used as a protein source to study the isolation and activity of peptides with several applications. Currently, the milk whey waste obtained in the production of cheese also represents a protein source from which active peptides could be isolated with potential industrial applications. The active properties of milk peptides and the results found with regard to their physiological effects have led to the classification of peptides as belonging to the group of ingredients of protein nature, appropriate for use in functional foods or pharmaceutical formulations. In this study, the main peptides obtained from milk protein and the past research studies about its production and biological activities will be explained. Second, an analysis will be made on the methods to determinate the biological activities, the separation of bioactive peptides and its structure identification. All of these form the base required to obtain synthetic peptides. Finally, we explain the experimental animal and human trials done in the past years. Nevertheless, more research is required on the design and implementation of equipment for the industrial production and separation of peptides. In addition, different authors suggest that more emphasis should therefore be given to preclinical studies, proving that results are consistent and that effects are demonstrated repeatedly by several research human groups. PMID:21917640

  15. 75 FR 6386 - Pesticide Products; Registration Applications for a New Active Ingredient Chemical; Demiditraz

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-09

    ... AGENCY Pesticide Products; Registration Applications for a New Active Ingredient Chemical; Demiditraz.... Product name: Demiditraz Technical. Active ingredient: Insecticide and Demiditraz at 100%. Proposed...., Kalamazoo, MI 49001. Product name: CA Acaricide. Active ingredient: Insecticide and Demiditraz at...

  16. 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

  17. EMG and force production of the flexor hallucis longus muscle in isometric plantarflexion and the push-off phase of walking.

    PubMed

    Péter, Annamária; Hegyi, András; Stenroth, Lauri; Finni, Taija; Cronin, Neil J

    2015-09-18

    Large forces are generated under the big toe in the push-off phase of walking. The largest flexor muscle of the big toe is the flexor hallucis longus (FHL), which likely contributes substantially to these forces. This study examined FHL function at different levels of isometric plantarflexion torque and in the push-off phase at different speeds of walking. FHL and calf muscle activity were measured with surface EMG and plantar pressure was recorded with pressure insoles. FHL activity was compared to the activity of the calf muscles. Force and impulse values were calculated under the big toe, and were compared to the entire pressed area of the insole to determine the relative contribution of big toe flexion forces to the ground reaction force. FHL activity increased with increasing plantarflexion torque level (F=2.8, P=0.024) and with increasing walking speed (F=11.608, P<0.001). No differences were observed in the relative contribution of the force under the big toe to the entire sole between different plantarflexion torque levels (F=0.836, P=0.529). On the contrary, in the push-off phase of walking, peak force under the big toe increased at a higher rate than force under the other areas of the plantar surface (F=3.801, P=0.018), implying a greater relative contribution to total force at faster speeds. Moreover, substantial differences were found between isometric plantarflexion and walking concerning FHL activity relative to that of the calf muscles, highlighting the task-dependant behaviour of FHL. PMID:26100463

  18. Atomic force microscopy reveals a dual collagen-binding activity for the staphylococcal surface protein SdrF.

    PubMed

    Herman-Bausier, Philippe; Dufrêne, Yves F

    2016-02-01

    Staphylococcus epidermidis causes nosocomial infections by colonizing and forming biofilms on indwelling medical devices. This process involves specific interactions between cell wall-anchored (CWA) proteins and host proteins adsorbed onto the biomaterial. Here, we have explored the molecular forces by which the S. epidermidis CWA protein serine-aspartate repeat protein F (SdrF) binds to type I collagen, by means of advanced atomic force microscopy (AFM) techniques. Using single-cell force spectroscopy, we found that SdrF mediates bacterial adhesion to collagen-coated substrates through both weak and strong bonds. Single-molecule force spectroscopy demonstrated that these bonds involve the A and B regions of SdrF, thus revealing that the protein is capable of dual ligand-binding activity. Both weak and strong bonds showed high dissociation rates, indicating they are much less stable than those formed by the well-characterized 'dock, lock and latch' mechanism. Collectively, our results show that CWA proteins can bind to ligands by novel mechanisms. We anticipate that AFM will greatly contribute to the identification of novel binding partners and binding mechanisms in staphylococcal CWA proteins. PMID:26481199

  19. [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

  20. Alcohol production from Jerusalem artichoke using yeasts with inulinase activity

    SciTech Connect

    Guiraud, J.P.; Daurelles, J.; Galzy, P.

    1981-07-01

    The obtaining of a fermentable extract from Jerusalem artichoke is simple. Yeasts with inulinase activity can be used to produce ethanol with good profitability. This method makes it possible to obtain 25 to 65 hl ethanol/ha with by-products usable as feed. (Refs. 19).

  1. Eliciting Production of L2 Target Structures through Priming Activities

    ERIC Educational Resources Information Center

    McDonough, Kim; Trofimovich, Pavel; Neumann, Heike

    2015-01-01

    This study focuses on the pedagogical applications of structural priming research in an English for academic purposes (EAP) context, investigating whether priming activities are an effective tool for eliciting production of target grammatical structures. University students across four EAP classes carried out a total of 6 information-exchange…

  2. Biological Activity of Recently Discovered Halogenated Marine Natural Products

    PubMed Central

    Gribble, Gordon W.

    2015-01-01

    This review presents the biological activity—antibacterial, antifungal, anti-parasitic, antiviral, antitumor, antiinflammatory, antioxidant, and enzymatic activity—of halogenated marine natural products discovered in the past five years. Newly discovered examples that do not report biological activity are not included. PMID:26133553

  3. DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS

    SciTech Connect

    Harold H. Schobert; M. Mercedes Maroto-Valer; Zhe Lu

    2003-09-30

    The increasing role of coal as a source of energy in the 21st century will demand environmental and cost-effective strategies for the use of coal combustion by-products (CCBPs), mainly unburned carbon in fly ash. Unburned carbon is nowadays regarded as a waste product and its fate is mainly disposal, due to the present lack of efficient routes for its utilization. However, unburned carbon is a potential precursor for the production of adsorbent carbons, since it has gone through a devolatilization process while in the combustor, and therefore, only requires to be activated. Accordingly, the principal objective of this work was to characterize and utilize the unburned carbon in fly ash for the production of activated carbons. The unburned carbon samples were collected from different combustion systems, including pulverized utility boilers, a utility cyclone, a stoker, and a fluidized bed combustor. LOI (loss-on-ignition), proximate, ultimate, and petrographic analyses were conducted, and the surface areas of the samples were characterized by N2 adsorption isotherms at 77K. The LOIs of the unburned carbon samples varied between 21.79-84.52%. The proximate analyses showed that all the samples had very low moisture contents (0.17 to 3.39 wt %), while the volatile matter contents varied between 0.45 to 24.82 wt%. The elemental analyses show that all the unburned carbon samples consist mainly of carbon with very little hydrogen, nitrogen, sulfur and oxygen In addition, the potential use of unburned carbon as precursor for activated carbon (AC) was investigated. Activated carbons with specific surface area up to 1075m{sup 2}/g were produced from the unburned carbon. The porosity of the resultant activated carbons was related to the properties of the unburned carbon feedstock and the activation conditions used. It was found that not all the unburned carbon samples are equally suited for activation, and furthermore, their potential as activated carbons precursors could be

  4. Dynamic control of aerodynamic forces on a moving platform using active flow control

    NASA Astrophysics Data System (ADS)

    Brzozowski, Daniel P.

    The unsteady interaction between trailing edge aerodynamic flow control and airfoil motion in pitch and plunge is investigated in wind tunnel experiments using a two degree-of-freedom traverse which enables application of time-dependent external torque and forces by servo motors. The global aerodynamic forces and moments are regulated by controlling vorticity generation and accumulation near the trailing edge of the airfoil using hybrid synthetic jet actuators. The dynamic coupling between the actuation and the time-dependent flow field is characterized using simultaneous force and particle image velocimetry (PIV) measurements that are taken phase-locked to the commanded actuation waveform. The effect of the unsteady motion on the model-embedded flow control is assessed in both trajectory tracking and disturbance rejection maneuvers. The time-varying aerodynamic lift and pitching moment are estimated from a PIV wake survey using a reduced order model based on classical unsteady aerodynamic theory. These measurements suggest that the entire flow over the airfoil readjusts within 2--3 convective time scales, which is about two orders of magnitude shorter than the characteristic time associated with the controlled maneuver of the wind tunnel model. This illustrates that flow-control actuation can be typically effected on time scales that are commensurate with the flow's convective time scale, and that the maneuver response is primarily limited by the inertia of the platform.

  5. Can aquatic worms enhance methane production from waste activated sludge?

    PubMed

    Serrano, Antonio; Hendrickx, Tim L G; Elissen, Hellen H J; Laarhoven, Bob; Buisman, Cees J N; Temmink, Hardy

    2016-07-01

    Although literature suggests that aquatic worms can help to enhance the methane production from excess activated sludge, clear evidence for this is missing. Therefore, anaerobic digestion tests were performed at 20 and at 30°C with sludge from a high-loaded membrane bioreactor, the aquatic worm Lumbriculus variegatus, feces from these worms and with mixtures of these substrates. A significant synergistic effect of the worms or their feces on methane production from the high-loaded sludge or on its digestion rate was not observed. However, a positive effect on low-loaded activated sludge, which generally has a lower anaerobic biodegradability, cannot be excluded. The results furthermore showed that the high-loaded sludge provides an excellent feed for L. variegatus, which is promising for concepts where worm biomass is considered a resource for technical grade products such as coatings and glues. PMID:26998797

  6. Bioactive activities of natural products against herpesvirus infection.

    PubMed

    Son, Myoungki; Lee, Minjung; Sung, Gi-Ho; Lee, Taeho; Shin, Yu Su; Cho, Hyosun; Lieberman, Paul M; Kang, Hyojeung

    2013-10-01

    More than 90% of adults have been infected with at least one human herpesvirus, which establish long-term latent infection for the life of the host. While anti-viral drugs exist that limit herpesvirus replication, many of these are ineffective against latent infection. Moreover, drug-resistant strains of herpesvirus emerge following chemotherapeutic treatment. For example, resistance to acyclovir and related nucleoside analogues can occur when mutations arise in either HSV thymidine kinase or DNA polymerases. Thus, there exists an unmet medical need to develop new anti-herpesvirus agents with different mechanisms of action. In this Review, we discuss the promise of anti-herpetic substances derived from natural products including extracts and pure compounds from potential herbal medicines. One example is Glycyrrhizic acid isolated from licorice that shows promising antiviral activity towards human gammaherpesviruses. Secondly, we discuss anti-herpetic mechanisms utilized by several natural products in molecular level. While nucleoside analogues inhibit replicating herpesviruses in lytic replication, some natural products can disrupt the herpesvirus latent infection in the host cell. In addition, natural products can stimulate immune responses against herpesviral infection. These findings suggest that natural products could be one of the best choices for development of new treatments for latent herpesvirus infection, and may provide synergistic anti-viral activity when supplemented with nucleoside analogues. Therefore, it is important to identify which natural products are more efficacious anti-herpetic agents, and to understand the molecular mechanism in detail for further advance in the anti-viral therapies. PMID:24173639

  7. The swim force as a body force

    NASA Astrophysics Data System (ADS)

    Yan, Wen; Brady, John

    2015-11-01

    Net (as opposed to random) motion of active matter results from an average swim (or propulsive) force. It is shown that the average swim force acts like a body force - an internal body force [Yan and Brady, Soft Matter, DOI:10.1039/C5SM01318F]. As a result, the particle-pressure exerted on a container wall is the sum of the swim pressure [Takatori et al., Phys. Rev. Lett., 2014, 113, 028103] and the `weight' of the active particles. A continuum mechanical description is possible when variations occur on scales larger than the run length of the active particles and gives a Boltzmann-like distribution from a balance of the swim force and the swim pressure. Active particles may also display `action at a distance' and accumulate adjacent to (or be depleted from) a boundary without any external forces. In the momentum balance for the suspension - the mixture of active particles plus fluid - only external body forces appear.

  8. Effects of cortical activations on enhancement of handgrip force during teeth clenching: an fMRI study.

    PubMed

    Kawakubo, Naomi; Miyamoto, Jun J; Katsuyama, Narumi; Ono, Takashi; Honda, Ei-Ichi; Kurabayashi, Tohru; Taira, Masato; Moriyama, Keiji

    2014-02-01

    We assessed the effect of teeth clenching on handgrip force behaviorally, and investigated cortical activity during the occurrence of facilitatory effects using functional magnetic resonance imaging (fMRI). Twenty-three participants were assessed as to whether they had habitual teeth clenching during maximal voluntary contraction (MVC) exertion, and 21 of them were identified to have such a habit. For those participants, behavioral testing showed that MVC with clenching was greater compared with without clenching (approximately 108% greater on average). Next, cortical activity was measured under gripping with clenching (GwC), gripping without clenching (GwoC), and teeth clenching (C) conditions. We found that the activity of the hand region in primary motor cortex (M1), cingulate motor area/supplementary motor area (CMA/SMA) and anterior cerebellum (AC) was greater in contrast of GwC vs. (GwoC+C). Furthermore, significant correlation was observed between the increasing ratio of the handgrip force and the % signal change in the hand region of M1 and AC, but not in CMA/SMA. These results suggest that the activation in the hand region of M1 and AC may facilitate the spinal motoneurons, and the activation in the hand region in M1 by clenching may be due to a signal from CMA/SMA. PMID:24326095

  9. Prediction of Active-Region CME Productivity from Magnetograms

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Gary, G. A.

    2004-01-01

    We report results of an expanded evaluation of whole-active-region magnetic measures as predictors of active-region coronal mass ejection (CME) productivity. Previously, in a sample of 17 vector magnetograms of 12 bipolar active regions observed by the Marshall Space Flight Center (MSFC) vector magnetograph, from each magnetogram we extracted a measure of the size of the active region (the active region s total magnetic flux a) and four measures of the nonpotentiality of the active region: the strong-shear length L(sub SS), the strong-gradient length L(sub SG), the net vertical electric current I(sub N), and the net-current magnetic twist parameter alpha (sub IN). This sample size allowed us to show that each of the four nonpotentiality measures was statistically significantly correlated with active-region CME productivity in time windows of a few days centered on the day of the magnetogram. We have now added a fifth measure of active-region nonpotentiality (the best-constant-alpha magnetic twist parameter (alpha sub BC)), and have expanded the sample to 36 MSFC vector magnetograms of 31 bipolar active regions. This larger sample allows us to demonstrate statistically significant correlations of each of the five nonpotentiality measures with future CME productivity, in time windows of a few days starting from the day of the magnetogram. The two magnetic twist parameters (alpha (sub 1N) and alpha (sub BC)) are normalized measures of an active region s nonpotentially in that they do not depend directly on the size of the active region, while the other three nonpotentiality measures (L(sub SS), L(sub SG), and I(sub N)) are non-normalized measures in that they do depend directly on active-region size. We find (1) Each of the five nonpotentiality measures is statistically significantly correlated (correlation confidence level greater than 95%) with future CME productivity and has a CME prediction success rate of approximately 80%. (2) None of the nonpotentiality

  10. JV Task 90 - Activated Carbon Production from North Dakota Lignite

    SciTech Connect

    Steven Benson; Charlene Crocker; Rokan Zaman; Mark Musich; Edwin Olson

    2008-03-31

    The Energy & Environmental Research Center (EERC) has pursued a research program for producing activated carbon from North Dakota lignite that can be competitive with commercial-grade activated carbon. As part of this effort, small-scale production of activated carbon was produced from Fort Union lignite. A conceptual design of a commercial activated carbon production plant was drawn, and a market assessment was performed to determine likely revenue streams for the produced carbon. Activated carbon was produced from lignite coal in both laboratory-scale fixed-bed reactors and in a small pilot-scale rotary kiln. The EERC was successfully able to upgrade the laboratory-scale activated carbon production system to a pilot-scale rotary kiln system. The activated carbon produced from North Dakota lignite was superior to commercial grade DARCO{reg_sign} FGD and Rheinbraun's HOK activated coke product with respect to iodine number. The iodine number of North Dakota lignite-derived activated carbon was between 600 and 800 mg I{sub 2}/g, whereas the iodine number of DARCO FGD was between 500 and 600 mg I{sub 2}/g, and the iodine number of Rheinbraun's HOK activated coke product was around 275 mg I{sub 2}/g. The EERC performed both bench-scale and pilot-scale mercury capture tests using the activated carbon made under various optimization process conditions. For comparison, the mercury capture capability of commercial DARCO FGD was also tested. The lab-scale apparatus is a thin fixed-bed mercury-screening system, which has been used by the EERC for many mercury capture screen tests. The pilot-scale systems included two combustion units, both equipped with an electrostatic precipitator (ESP). Activated carbons were also tested in a slipstream baghouse at a Texas power plant. The results indicated that the activated carbon produced from North Dakota lignite coal is capable of removing mercury from flue gas. The tests showed that activated carbon with the greatest iodine number

  11. Microfluidic Chip for the Photocatalytic Production of Active Chlorine.

    PubMed

    Elmas, Sait; Ambroz, Filip; Chugh, Dipankar; Nann, Thomas

    2016-05-17

    Active chlorine is the most powerful microbicidal reagent in swimming pools, potable water, hospitals, and medical surgeries. Its production mainly relies on reactive inorganic intermediates and electrochemical methods that involve undesired waste products and high energy as well as material costs. In this study, we fabricated a low-cost chip based on sputter-coated thin films of silver (Ag) that acted as recyclable and effective photoelectrode for the photocatalytic production of active chlorine (HOCl) from aqueous media and artificial sunlight. The photoelectrode was electrochemically activated to AgCl at low overpotentials between 0.2 and 0.4 V vs Ag|AgCl (3 M KCl) and photocatalytically reduced to Ag(0) for 15 consecutive cycles, showing the electrode still being active. However, because of poor adhesion properties on the selected substrates, degradation effects were observed over time. Furthermore, the Ag@AgCl photoelectrode was integrated into a microfluidic chip, and we showed for the first time a light-driven microfluidic chip generating a constant stream of active chlorine. PMID:27115714

  12. Reprocessing of used tires into activated carbon and other products

    SciTech Connect

    Teng, H.; Serio, M.A.; Wojtowicz, M.A.; Bassilakis, R.; Solomon, P.R.

    1995-09-01

    Landfilling used tires which are generated each year in the US is increasingly becoming an unacceptable solution. A better approach, from an environmental and economic standpoint, is to thermally reprocess the tires into valuable products such as activated carbon, other solid carbon forms (carbon black, graphite, and carbon fibers), and liquid fuels. In this study, high surface area activated carbons (> 800 m{sup 2}/g solid product) were produced in relatively high yields by pyrolysis of tires at up to 900 C, followed by activation in CO{sub 2} at the same temperature. The surface areas of these materials are comparable with those of commercial activated carbons. The efficiency of the activation process (gain in specific surface area/loss in mass) was greatest (up to 138 m{sup 2}/g original tire) when large pieces of tire material were used ({approximately} 170 mg). Oxygen pretreatment of tires was found to enhance both the yield and the surface area of the carbon product. High-pressure treatment of tires at low temperatures (< 400 C) is an alternative approach if the recovery of carbon black or fuel oils is the primary objective.

  13. Evidence that the spectrin network and a nonosmotic force control the fusion product morphology in electrofused erythrocyte ghosts.

    PubMed Central

    Chernomordik, L V; Sowers, A E

    1991-01-01

    The conversion of the membrane area in the "contact zones" shared by erythrocyte ghosts held in contact by dielectrophoresis into a fusion product by electrofusion was studied by both light and electron microscopy. Fusion products fell into two categories: (a) those with a freely expanding open lumen which ended in the "giant cell morphology" and with considerable internal vesicle membrane fragments, and (b) linear chains of polyghosts with long term stability but having planar diaphragms at the ghost-ghost junctions. Thin section electron microscopy showed each of these planar diaphragms to be a double membrane septum multiply-perforated with fusion pores. Heat and low ionic strength treatments known to denature or detach spectrin caused the stable planar diaphragms to dissolve, thereby quickly converting the polyghost chains to the giant cell morphology, thereby suggesting that spectrin restricts fusion zone diameter expansion if it is intact. Other indications suggest that the expansion of the open lumens appears to take place as a result of one or more membrane-specific forces with a nonosmotic origin but this tendency to expansion can be overcome if the spectrin network on only one side of a contact zone is intact. Images FIGURE 2 FIGURE 4 FIGURE 5 FIGURE 7 PMID:1760502

  14. Characterization of forced degradation products of pazopanib hydrochloride by UHPLC-Q-TOF/MS and in silico toxicity prediction.

    PubMed

    Patel, Prinesh N; Kalariya, Pradipbhai D; Sharma, Mahesh; Garg, Prabha; Talluri, M V N Kumar; Gananadhamu, S; Srinivas, R

    2015-07-01

    Pazopanib (PZ), an anti-cancer drug, was subjected to forced degradation under hydrolytic (acid, base and neutral), oxidative, photolytic and thermal stress conditions as per International Conference on Harmonization guidelines. A selective stability indicating validated method was developed using a Waters Acquity UPLC HSS T3 (100 × 2.1 mm, 1.7 µm) column in gradient mode with ammonium acetate buffer (10 mM, pH 5.0) and acetonitrile. PZ was found to degrade only in photolytic conditions to produce six transformation products (TPs). All the TPs were identified and characterized by liquid chromatography/atmospheric pressure chemical ionization-quadrupole-time of flight mass spectrometry experiments in combination with accurate mass measurements. Plausible mechanisms have been proposed for the formation of TPs. In silico toxicity was predicted using TOPKAT and DEREK softwares for all the TPs. The TP, N4-(2,3-dimethyl-2H-indazol-6-yl)-N4-methylpyrimidine-2,4-diamine, was found to be genotoxic, whereas all other TPs with sulfonamide moiety were hepatotoxic. The data reported here are expected to be of significance as this study foresees the formation of one potential genotoxic and five hepatotoxic degradation/transformation products. PMID:26349647

  15. 78 FR 22512 - Foreign-Trade Zone (FTZ) 225-Springfield, Missouri; Notification of Proposed Production Activity...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-16

    ... Production Activity; General Dynamics Ordnance and Tactical Systems Munitions Services (Demilitarization of... notification of proposed production activity to the FTZ Board on behalf of General Dynamics Ordnance...

  16. Ecological and Pharmacological Activities of Antarctic Marine Natural Products.

    PubMed

    Avila, Conxita

    2016-06-01

    Antarctic benthic communities are regulated by abundant interactions of different types among organisms, such as predation, competition, etc. Predators are usually sea stars, with omnivorous habits, as well as other invertebrates. Against this strong predation pressure, many organisms have developed all sorts of defensive strategies, including chemical defenses. Natural products are thus quite common in Antarctic organisms with an important ecological and pharmacological potential. In this paper, the chemical defenses of the Antarctic organisms studied during the ECOQUIM and ACTIQUIM projects, as well as their pharmacological potential, are reviewed. For the ecological defenses, predation against the sea star Odontaster validus is analyzed and evaluated along depth gradients as well as considering the lifestyle of the organisms. For the pharmacological activity, the anticancer, anti-inflammatory, and antibacterial activities tested are evaluated here. Very often, only crude extracts or fractions have been tested so far, and therefore, the natural products responsible for such activities remain yet to be identified. Even if the sampling efforts are not uniform along depth, most ecologically active organisms are found between 200 and 500 m depth. Also, from the samples studied, about four times more sessile organisms possess chemical defenses against the sea star than the vagile ones; these represent 50 % of sessile organisms and 35 % of the vagile ones, out of the total tested, being active. Pharmacological activity has not been tested uniformly in all groups, but the results show that relevant activity is found in different phyla, especially in Porifera, Cnidaria, Bryozoa, and Tunicata, but also in others. No relationship between depth and pharmacological activity can be established with the samples tested so far. More studies are needed in order to better understand the ecological relationships among Antarctic invertebrates mediated by natural products and

  17. Deoxygedunin, a natural product with potent neurotrophic activity in mice.

    PubMed

    Jang, Sung-Wuk; Liu, Xia; Chan, Chi Bun; France, Stefan A; Sayeed, Iqbal; Tang, Wenxue; Lin, Xi; Xiao, Ge; Andero, Raul; Chang, Qiang; Ressler, Kerry J; Ye, Keqiang

    2010-01-01

    Gedunin, a family of natural products from the Indian neem tree, possess a variety of biological activities. Here we report the discovery of deoxygedunin, which activates the mouse TrkB receptor and its downstream signaling cascades. Deoxygedunin is orally available and activates TrkB in mouse brain in a BDNF-independent way. Strikingly, it prevents the degeneration of vestibular ganglion in BDNF -/- pups. Moreover, deoxygedunin robustly protects rat neurons from cell death in a TrkB-dependent manner. Further, administration of deoxygedunin into mice displays potent neuroprotective, anti-depressant and learning enhancement effects, all of which are mediated by the TrkB receptor. Hence, deoxygedunin imitates BDNF's biological activities through activating TrkB, providing a powerful therapeutic tool for treatment of various neurological diseases. PMID:20644624

  18. Effects of DO levels on surface force, cell membrane properties and microbial community dynamics of activated sludge.

    PubMed

    Ma, Si-Jia; Ding, Li-Li; Huang, Hui; Geng, Jin-Ju; Xu, Ke; Zhang, Yan; Ren, Hong-Qiang

    2016-08-01

    In this paper, we employ atomic force microscopy (AFM), fluorescence recovery after photobleaching (FRAP) technique, phospholipid fatty acids (PLFA) and MiSeq analysis to study the effects of traditional dissolved oxygen (DO) levels (0.71-1.32mg/L, 2.13-3.02mg/L and 4.31-5.16mg/L) on surface force, cell membrane properties and microbial community dynamics of activated sludge. Results showed that low DO level enhanced the surface force and roughness of activated sludge; the medium DO level decreased cell membrane fluidity by reducing the synthesis of branched fatty acids in the cell membrane; high DO level resulted in the highest protein content in the effluent by EEM scanning. Abundance of Micropruina, Zoogloea and Nakamurella increased and Paracoccus and Rudaea decreased with the increase of DO levels. RDA analysis suggested that saturated fatty acids (SFA), anteiso-fatty acids (AFA) and iso-fatty acids (IFA) were closely related to effluent quality as well as some genera. PMID:27187569

  19. Natural Product Anacardic Acid from Cashew Nut Shells Stimulates Neutrophil Extracellular Trap Production and Bactericidal Activity.

    PubMed

    Hollands, Andrew; Corriden, Ross; Gysler, Gabriela; Dahesh, Samira; Olson, Joshua; Raza Ali, Syed; Kunkel, Maya T; Lin, Ann E; Forli, Stefano; Newton, Alexandra C; Kumar, Geetha B; Nair, Bipin G; Perry, J Jefferson P; Nizet, Victor

    2016-07-01

    Emerging antibiotic resistance among pathogenic bacteria is an issue of great clinical importance, and new approaches to therapy are urgently needed. Anacardic acid, the primary active component of cashew nut shell extract, is a natural product used in the treatment of a variety of medical conditions, including infectious abscesses. Here, we investigate the effects of this natural product on the function of human neutrophils. We find that anacardic acid stimulates the production of reactive oxygen species and neutrophil extracellular traps, two mechanisms utilized by neutrophils to kill invading bacteria. Molecular modeling and pharmacological inhibitor studies suggest anacardic acid stimulation of neutrophils occurs in a PI3K-dependent manner through activation of surface-expressed G protein-coupled sphingosine-1-phosphate receptors. Neutrophil extracellular traps produced in response to anacardic acid are bactericidal and complement select direct antimicrobial activities of the compound. PMID:27226531

  20. Aerobic activated sludge transformation of methotrexate: identification of biotransformation products.

    PubMed

    Kosjek, Tina; Negreira, Noelia; de Alda, Miren López; Barceló, Damià

    2015-01-01

    This study describes the biotransformation of cytostatic and immunosuppressive pharmaceutical methotrexate. Its susceptibility to microbiological breakdown was studied in a batch biotransformation system, in presence or absence of carbon source and at two activated sludge concentrations. The primary focus of the present study are methotrexate biotransformation products, which were tentatively identified by the ultra-high performance liquid chromatography-quadrupole--Orbitrap-MS. Data-dependent experiments, combining full-scan MS data with product ion spectra were acquired, in order to identify the molecular ions of methotrexate transformation products, to propose the molecular formulae and to elucidate their chemical structures. Among the identified transformation products 2,4-diamino-N10-methyl-pteroic acid is most abundant and persistent. Other biotransformation reactions involve demethylation, oxidative cleavage of amine, cleavage of C-N bond, aldehyde to carboxylate transformation and hydroxylation. Finally, a breakdown pathway is proposed, which shows that most of methotrexate breakdown products retain the diaminopteridine structural segment. In total we propose nine transformation products, among them eight are described as methotrexate transformation products for the first time. PMID:24835159

  1. Surface electromyography activity of the rectus abdominis, internal oblique, and external oblique muscles during forced expiration in healthy adults.

    PubMed

    Ito, Kenichi; Nonaka, Koji; Ogaya, Shinya; Ogi, Atsushi; Matsunaka, Chiaki; Horie, Jun

    2016-06-01

    We aimed to characterize rectus abdominis, internal oblique, and external oblique muscle activity in healthy adults under expiratory resistance using surface electromyography. We randomly assigned 42 healthy adult subjects to 3 groups: 30%, 20%, and 10% maximal expiratory intraoral pressure (PEmax). After measuring 100% PEmax and muscle activity during 100% PEmax, the activity and maximum voluntary contraction of each muscle during the assigned experimental condition were measured. At 100% PEmax, the external oblique (p<0.01) and internal oblique (p<0.01) showed significantly elevated activity compared with the rectus abdominis muscle. Furthermore, at 20% and 30% PEmax, the external oblique (p<0.05 and<0.01, respectively) and the internal oblique (p<0.05 and<0.01, respectively) showed significantly elevated activity compared with the rectus abdominis muscle. At 10% PEmax, no significant differences were observed in muscle activity. Although we observed no significant difference between 10% and 20% PEmax, activity during 30% PEmax was significantly greater than during 20% PEmax (external oblique: p<0.05; internal oblique: p<0.01). The abdominal oblique muscles are the most active during forced expiration. Moreover, 30% PEmax is the minimum intensity required to achieve significant, albeit very slight, muscle activity during expiratory resistance. PMID:27077819

  2. Move with Science: Energy, Force, & Motion. An Activities-Based Teacher's Guide.

    ERIC Educational Resources Information Center

    Beven, Roy Q.

    The secondary school level activities contained in this book use the subject of transportation to teach the basic concepts of physics and several areas of human biology. The material is organized into sections including curriculum design, activities, background readings, and resources. Activities focus on such topics as notions of motion stability…

  3. High-latitude forcing of diatom productivity in the southern Agulhas Plateau during the past 350 kyr

    NASA Astrophysics Data System (ADS)

    Romero, O. E.; Kim, J.-H.; Bárcena, M. A.; Hall, I. R.; Zahn, R.; Schneider, R.

    2015-02-01

    The hydrography of the Indian-Atlantic Ocean gateway has been connected to high-latitude climate dynamics by oceanic and atmospheric teleconnections on orbital and suborbital timescales. A wealth of sedimentary records aiming at reconstructing the late Pleistocene paleoceanography around the southern African continent has been devoted to understanding these linkages. Most of the records are, however, clustered close to the southern South African tip, with comparatively less attention devoted to areas under the direct influence of frontal zones of the Southern Ocean/South Atlantic. Here we present data of the composition and concentration of the diatom assemblage together with bulk biogenic content and the alkenone-based sea surface temperature (SST) variations for the past 350 kyr in the marine sediment core MD02-2588 (approximately 41°S, 26°E) recovered from the southern Agulhas Plateau. Variations in biosiliceous productivity show a varying degree of coupling with Southern Hemisphere paleoclimate records following a glacial-interglacial cyclicity. Ecologically well-constrained groups of diatoms record the glacial-interglacial changes in water masses dynamics, nutrient availability, and stratification of the upper ocean. The good match between the glacial maxima of total diatoms concentration, Chaetoceros spores abundance, and opal content with the maximum seasonal cover of Antarctic ice and the atmospheric dust records points to a dominant Southern Hemisphere forcing of diatom production. Suborbital variability of SST suggests rapid latitudinal migrations of the Subtropical Front and associated water masses over the southern Agulhas Plateau, following millennial contractions and expansions of the subtropical gyres. Warmings of the upper ocean over site MD02-2588 during terminations IV to I occurred earlier than that in the Antarctic Vostok, which is indicative of a Northern Hemisphere lead. Our multiparameter reconstruction highlights how high

  4. Measurement of Contractile Activity in Small Animal's Digestive Organ by Carbon Nanotube-Based Force Transducer

    NASA Astrophysics Data System (ADS)

    Hirata, Takamichi; Takeda, Naoki; Tsutsui, Chihiro; Koike, Kanako; Shimatani, Yuichi; Sakai, Takafumi; Akiya, Masahiro; Taguchi, Akira

    2011-03-01

    A carbon nanotube (CNT)-based force transducer designed to be embedded in the body of a live animal was fabricated and implanted into the stomach of a rat omit to measure contractile movement. The transducer comprised dispersed poly(ethylene glycol)-grafted multiwalled CNTs applied to a comb-like Au-electrode formed on a poly(dimethylsiloxane) sheet. The implanted rat was injected with acetylcholine to induce muscular contractions and changes in the resistance of the transducer were measured. Such changes arise owing to strain in the CNT network upon distortion. The measured resistance change was found to be proportional to the concentration of injected acetylcholine.

  5. ACTIVITY OF NATURAL PRODUCTS AGAINST SOME PHYTOPATHOGENIC FUNGI.

    PubMed

    La Torre, A; Caradonia, F; Gianferro, M; Molinu, M G; Battaglia, V

    2014-01-01

    The requirement of environmental protection and food safety is perceived with always major interest by public opinion and it is consistent with European Union legislation on the sustainable use of pesticides (Directive 2009/128/EC). This directive requires member states to promote low pesticide-input, giving priority to non-chemical methods and low risk plant protection products. In order to contribute to the achievement of these objectives antifungal activity of natural substances, characterized by a good toxicological and ecotoxicological profile, was tested. Essential oil of Melaleuca alternifolia, essential oil of Syzygium aromaticum and extract from Mimosa tenuiflora were tested against Alternaria alternata, Botrytis cinerea and Fusarium oxysporum f. sp. lycopersici (races 1 and 2). In vitro tests involved determination of radial growth of the colonies of fungi in the presence of varying concentrations of tested products in agar media and determination of germination percentage in the presence of tested product at various concentrations. The products based on essential oil of M. alternifolia were also tested in vivo on tomato fruits wounded and artificially inoculated with A. alternata or with B. cinerea. The in vitro tests showed the antifungal activity of both essential oils instead the extract from M. tenuiflora exhibited poor antifungal activity and only against A. alternata and B. cinerea. The results on tomato fruits showed inhibition of grey mould and black mould by essential oil of M. alternifolia. The antifungal activity increased with increasing concentrations. In conclusion, the obtained results in the present study showed promising prospects for the utilisation of investigated products to reduce the using of antifungal chemicals and to achieve a more sustainable use of pesticides. PMID:26080478

  6. Phospholipid Ozonation Products Activate the 5-Lipoxygenase Pathway in Macrophages.

    PubMed

    Zemski Berry, Karin A; Murphy, Robert C

    2016-08-15

    Ozone is a highly reactive environmental toxicant that can react with the double bonds of lipids in pulmonary surfactant. This study was undertaken to investigate the proinflammatory properties of the major lipid-ozone product in pulmonary surfactant, 1-palmitoyl-2-(9'-oxo-nonanoyl)-glycerophosphocholine (16:0/9al-PC), with respect to eicosanoid production. A dose-dependent increase in the formation of 5-lipoxygenase (5-LO) products was observed in murine resident peritoneal macrophages (RPM) and alveolar macrophages (AM) upon treatment with 16:0/9al-PC. In contrast, the production of cyclooxygenase (COX) derived eicosanoids did not change from basal levels in the presence of 16:0/9al-PC. When 16:0/9al-PC and the TLR2 ligand, zymosan, were added to RPM or AM, an enhancement of 5-LO product formation along with a concomitant decrease in COX product formation was observed. Neither intracellular calcium levels nor arachidonic acid release was influenced by the addition of 16:0/9al-PC to RPM. Results from mitogen-activated protein kinase (MAPK) inhibitor studies and direct measurement of phosphorylation of MAPKs revealed that 16:0/9al-PC activates the p38 MAPK pathway in RPM, which results in the activation of 5-LO. Our results indicate that 16:0/9al-PC has a profound effect on the eicosanoid pathway, which may have implications in inflammatory pulmonary disease states where eicosanoids have been shown to play a role. PMID:27448436

  7. Products of enteropathogenic Escherichia coli inhibit lymphocyte activation and lymphokine production.

    PubMed Central

    Klapproth, J M; Donnenberg, M S; Abraham, J M; Mobley, H L; James, S P

    1995-01-01

    The aim of this study was to determine whether products of enteric bacteria are able to regulate lymphocyte activation and cytokine production. Whole bacteria and bacterial lysates from different strains of Escherichia coli were tested for their ability to inhibit cytokine production by peripheral blood mononuclear cells as determined by reverse transcription-PCR, Northern (RNA) blotting of cellular RNA, or enzyme-linked immunosorbent assay for cytokine protein. Lysates from two pathogenic strains of E. coli, enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli, inhibited mitogen-stimulated expression of interleukin-2 (IL-2), IL-4, IL-5, and gamma interferon. IL-1 beta, IL-6, IL-8, IL-10, IL-12, and Rantes mRNA expression was not affected. The inhibitory activity was dose dependent, protease and heat sensitive, nondialyzable, and not due to cellular toxicity. The inhibitory activity remained in EPEC strains having mutations in known virulence factors. Nonpathogenic E. coli HB101 transformed with a 22-kb cosmid clone derived from EPEC chromosomal DNA expressed the inhibitory activity. Thus, certain strains of pathogenic E. coli express a protein or proteins encoded by chromosomal genes that selectively inhibit lymphocyte activation and lymphokine production. Therefore, immunosuppressive factors produced by pathogenic bacteria could be important in modifying gastrointestinal immune responses in enteric bacterial infections or gastrointestinal autoimmune diseases. PMID:7768605

  8. 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.

  9. Acceleration of catalytic activity of calcium oxide for biodiesel production.

    PubMed

    Kawashima, Ayato; Matsubara, Koh; Honda, Katsuhisa

    2009-01-01

    This research was aimed at studying the acceleration of the catalytic activity of calcium oxide (CaO) for developing an effective heterogeneous catalyst for biodiesel production by the transesterification of plant oil with methanol. CaO was activated by pretreatment with methanol and was used for the transesterification reaction. The activation and transesterification reaction conditions were examined. The obtained optimal reaction conditions were 0.1-g CaO, 3.9-g methanol, 15-g rapeseed oil, and 1.5-h activation time at room temperature that provided methyl ester in approximately 90% yield within a reaction time of 3h at 60 degrees C. The activation mechanism was also investigated, and the proposed mechanism is as follows. By pretreatment with methanol, a small amount of CaO gets converted into Ca(OCH(3))(2) that acts as an initiating reagent for the transesterification reaction and produces glycerin as a by-product. Subsequently, a calcium-glycerin complex, formed due to the reaction of CaO with glycerin, functions as the main catalyst and accelerates the transesterification reaction. PMID:18684617

  10. Antidepressant-like activity of liposomal formulation containing nimodipine treatment in the tail suspension test, forced swim test and MAOB activity in mice.

    PubMed

    Moreno, Lina Clara Gayoso E Almendra Ibiapina; Rolim, Hercília Maria Lins; Freitas, Rivelilson Mendes; Santos-Magalhães, Nereide Stela

    2016-09-01

    Previous studies have shown that intracellular calcium ion dysfunction may be an etiological factor in affective illness. Nimodipine (NMD) is a Ca(2+) channel blocker that has been extensively investigated for therapy of central nervous system (CNS) disorders. In this work, we have evaluated the antidepressant-like activity of nimodipine encapsulated into liposomes (NMD-Lipo) in mice through tail suspension and forced swim assays, as well as MAOB activity. During the tail suspension test, the administration of NMD-Lipo at 0.1, 1 and 10mg/kg was able to promote a reduction in the immobility time of animals greater than the positive control (imipramine). In the forced swim test, the immobility time of mice treated with NMD-Lipo was reduced. This reduction was significantly greater than that found in the animals treated with imipramine and paroxetine. This may suggest that NMD-Lipo provides more antidepressant-like activity than in positive controls. The groups that received a combination of liposomal NMD and antidepressant drugs showed lower immobility time than the groups, which were treated only with imipramine or paroxetine. The mice treated with the combination of NMD-Lipo and reserpine presented an increase in the time of immobility compared with animals treated only with NMD-Lipo. There was a significant decrease in MAOB activity in animals treated with NMD-Lipo compared with untreated animals. The results of the tail suspension test, forced swim test and MAOB activity suggested that the antidepressant activity of NMD-Lipo may be related to an increase in the cerebral monoamine concentrations. PMID:27270234

  11. Chitinase activity on amorphous chitin thin films: a quartz crystal microbalance with dissipation monitoring and atomic force microscopy study.

    PubMed

    Wang, Chao; Kittle, Joshua D; Qian, Chen; Roman, Maren; Esker, Alan R

    2013-08-12

    Chitinases are widely distributed in nature and have wide-ranging pharmaceutical and biotechnological applications. This work highlights a real-time and label-free method to assay Chitinase activity via a quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM). The chitin substrate was prepared by spincoating a trimethylsilyl chitin solution onto a silica substrate, followed by regeneration to amorphous chitin (RChi). The QCM-D and AFM results clearly showed that the hydrolysis rate of RChi films increased as Chitinase (from Streptomyces griseus) concentrations increased, and the optimal temperature and pH for Chitinase activity were around 37 °C and 6-8, respectively. The Chitinase showed greater activity on chitin substrates, having a high degree of acetylation, than on chitosan substrates, having a low degree of acetylation. PMID:23822524

  12. Thermal activation at moderate-to-high and high damping: finite barrier effects and force spectroscopy.

    PubMed

    Mazo, J J; Fajardo, O Y; Zueco, D

    2013-03-14

    We study the thermal escape problem in the moderate-to-high and high damping regime of a system with a parabolic barrier. We present a formula that matches our numerical results accounting for finite barrier effects, and compare it with previous works. We also show results for the full damping range. We quantitatively study some aspects on the relation between mean first passage time and the definition of an escape rate. To finish, we apply our results and considerations in the framework of force spectroscopy problems. We study the differences on the predictions using the different theories and discuss the role of γF[over dot] as the relevant parameter at high damping. PMID:23514463

  13. Active management of naturally separated flow over a solid surface. Part 1. The forced reattachment process

    NASA Astrophysics Data System (ADS)

    Darabi, A.; Wygnanski, I.

    2004-07-01

    The forced reattachment of flow to an inclined flat surface, simulating a simple flap, was investigated experimentally. The transition from a separated to an attached state of the flow was initiated by an abrupt change in the frequency and the amplitude of periodic perturbations emanating from a slot at the flap shoulder. The excitation parameters determined the total duration of the reattachment process. Minimum reattachment time occurred at an optimal excitation frequency of F_{scriptsizeopt}(+) ≈ 1.5, which was independent of amplitude and flap inclination. The control over the process was achieved by enhancing large spanwise vortices in the flow. Spatial amplification of consecutive vortices induces mean transport of fluid away from the flap surface which causes the main stream to reattach. The time scales of the excitation are at least an order of magnitude smaller than the typical reattachment times.

  14. Thermal activation at moderate-to-high and high damping: Finite barrier effects and force spectroscopy

    NASA Astrophysics Data System (ADS)

    Mazo, J. J.; Fajardo, O. Y.; Zueco, D.

    2013-03-01

    We study the thermal escape problem in the moderate-to-high and high damping regime of a system with a parabolic barrier. We present a formula that matches our numerical results accounting for finite barrier effects, and compare it with previous works. We also show results for the full damping range. We quantitatively study some aspects on the relation between mean first passage time and the definition of an escape rate. To finish, we apply our results and considerations in the framework of force spectroscopy problems. We study the differences on the predictions using the different theories and discuss the role of γ dot{F} as the relevant parameter at high damping.

  15. Active Desiccant-Based Preconditioning Market Analysis and Product Development

    SciTech Connect

    Fischer, J.

    2001-01-11

    The Phase 1 report (ORNL/Sub/94-SVO44/1), completed earlier in this program, involved a comprehensive field survey and market analysis comparing various specialized outdoor air handling units. This initial investigation included conventional cooling and reheat, conventional cooling with sensible recovery, total energy recovery systems (passive desiccant technology) and various active desiccant systems. The report concluded that several markets do promise a significant sales opportunity for a Climate Changer-based active desiccant system offering. (Climate Changer is a registered trademark of Trane Company.) This initial market analysis defined the wants and needs of the end customers (design engineers and building owners), which, along with subsequent information included in this report, have been used to guide the determination of the most promising active desiccant system configurations. This Phase 2 report begins with a summary of a more thorough investigation of those specific markets identified as most promising for active desiccant systems. Table 1 estimates the annual sales potential for a cost-effective product line of active desiccant systems, such as that built from Climate Changer modules. The Product Development Strategy section describes the active desiccant system configurations chosen to best fit the needs of the marketplace while minimizing system options. Key design objectives based on market research are listed in this report for these active desiccant systems. Corresponding performance goals for the dehumidification wheel required to meet the overall system design objectives are also defined. The Performance Modeling section describes the strategy used by SEMCO to design the dehumidification wheels integrated into the prototype systems currently being tested as part of the U.S. Department of Energy's Advanced Desiccant Technology Program. Actual performance data from wheel testing was used to revise the system performance and energy analysis

  16. Trunk muscular activation patterns and responses to transient force perturbation in persons with self-reported low back pain.

    PubMed

    Stokes, Ian A F; Fox, James R; Henry, Sharon M

    2006-05-01

    Trunk stability requires muscle stiffness associated with appropriate timing and magnitude of activation of muscles. Abnormality of muscle function has been implicated as possible cause or consequence of back pain. This experimental study compared trunk muscle activation and responses to transient force perturbations in persons with and without self-reported history of low back pain. The objective was to determine whether or not history of back pain was associated with (1) altered anticipatory preactivation of trunk muscles or altered likelihood of muscular response to a transient force perturbation and (2) altered muscle activation patterns during a ramped effort. Twenty-one subjects who reported having back pain (LBP group) and twenty-three reporting no recent back pain (NLBP group) were tested while each subject stood in an apparatus with the pelvis immobilized. They performed 'ramped-effort' tests (to a voluntary maximum effort), and force perturbation tests. Resistance was provided by a horizontal cable from the thorax to one of five anchorage points on a wall track to the subject's right at angles of 0 degrees, 45 degrees, 90 degrees, 135 degrees and 180 degrees to the forward direction. In the perturbation tests, subjects first pulled against the cable to generate an effort nominally 15% or 30% of their maximum extension effort. The effort and the EMG activity of five right/left pairs of trunk muscles were recorded, and muscle responses were detected. In the ramped-effort tests the gradient of the EMG-effort relationship provided a measure of each muscle's activation. On average, the LBP group subjects activated their dorsal muscles more than the NLBP group subjects in a maximum effort task when the EMG values were normalized for the maximum EMG, but this finding may have resulted from lesser maximum effort generated by LBP subjects. Greater muscle preactivation was recorded in the LBP group than the NLBP group just prior to the perturbation. The likelihood

  17. 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.

  18. Summary of activities to remove the aircraft hydrant system (Panero site) at March Air Force Base, California

    SciTech Connect

    Hendrian, G.L.

    1993-06-01

    This document summarizes the activities to remove the underground storage tank farm (Panero Site, Operable Unit 3, Installation Restoration Program) used for aircraft refueling at March AFB. This summary report is organized into four sections: introduction--gives the scope, information summary, and composition of the report; planned work scope--states the scope of work as provided in the Performance Work Statement for Removal of Aircraft Fuel Hydrant System March Air Force Base, California; demolition results--records the accomplishments for each task defined in the Performance Work Statement; and recycling efforts--record the efforts to reduce generating unnecessary waste.

  19. 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.

  20. 78 FR 10167 - Pesticide Products; Registration Applications for a New Active Ingredient

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-13

    ... AGENCY Pesticide Products; Registration Applications for a New Active Ingredient AGENCY: Environmental... products containing an active ingredient not included in any currently registered pesticide products... agricultural producer, food manufacturer, or pesticide manufacturer. The following list of North...

  1. Modulation of the Relationship Between External Knee Adduction Moments and Medial Joint Contact Forces Across Subjects and Activities

    PubMed Central

    Trepczynski, Adam; Kutzner, Ines; Bergmann, Georg; Taylor, William R; Heller, Markus O

    2014-01-01

    Objective The external knee adduction moment (EAM) is often considered a surrogate measure of the distribution of loads across the tibiofemoral joint during walking. This study was undertaken to quantify the relationship between the EAM and directly measured medial tibiofemoral contact forces (Fmed) in a sample of subjects across a spectrum of activities. Methods The EAM for 9 patients who underwent total knee replacement was calculated using inverse dynamics analysis, while telemetric implants provided Fmed for multiple repetitions of 10 activities, including walking, stair negotiation, sit-to-stand activities, and squatting. The effects of the factors “subject” and “activity” on the relationships between Fmed and EAM were quantified using mixed-effects regression analyses in terms of the root mean square error (RMSE) and the slope of the regression. Results Across subjects and activities a good correlation between peak EAM and Fmed values was observed, with an overall R2 value of 0.88. However, the slope of the linear regressions varied between subjects by up to a factor of 2. At peak EAM and Fmed, the RMSE of the regression across all subjects was 35% body weight (%BW), while the maximum error was 127 %BW. Conclusion The relationship between EAM and Fmed is generally good but varies considerably across subjects and activities. These findings emphasize the limitation of relying solely on the EAM to infer medial joint loading when excessive directed cocontraction of muscles exists and call for further investigations into the soft tissue–related mechanisms that modulate the internal forces at the knee. PMID:24470261

  2. [Activity of hydrogen sulfide production enzymes in kidneys of rats].

    PubMed

    Mel'nyk, A V; Pentiuk, O O

    2009-01-01

    An experimental research of activity and kinetic descriptions of enzymes participating in formation of hydrogen sulfide in the kidney of rats has been carried out. It was established that cystein, homocystein and thiosulphate are the basic substrates for hydrogen sulfide synthesis. The higest activity for hydrogen sulfide production belongs to thiosulfate-dithiolsulfurtransferase and cysteine aminotransferase, less activity is characteristic of cystathionine beta-synthase and cystathio-nine gamma-lyase. The highest affinity to substrate is registered for thiosulfate-dithiolsulfurtransferase and cystathionine gamma-lyase. It is discovered that the substrate inhibition is typical of all hydrogen sulfide formation enzymes, although this characteristic is the most expressed thiosulfat-dithiolsulfurtransferase. PMID:20387629

  3. Production and characterization of activated carbons from cereal grains

    SciTech Connect

    Venkatraman, A.; Walawender, W.P.; Fan, L.T.

    1996-12-31

    The term, activated carbon, is a generic name for a family of carbonaceous materials with well-developed porosities and consequently, large adsorptive capacities. Activated carbons are increasingly being consumed worldwide for environmental applications such as separation of volatiles from bulk gases and purification of water and waste-water streams. The global annual production is estimated to be around 300 million kilograms, with a rate of increase of 7% each year. Activated carbons can be prepared from a variety of raw materials. Approximately, 60% of the activated carbons generated in the United States is produced from coal; 20%, from coconut shells; and the remaining 20% from wood and other sources of biomass. The pore structure and properties of activated carbons are influenced by the nature of the starting material and the initial physical and chemical conditioning as well as the process conditions involved in its manufacture. The porous structures of charcoals and activated carbons obtained by the carbonization of kernels have been characterized.

  4. An obligately aerobic soil bacterium activates fermentative hydrogen production to survive reductive stress during hypoxia

    PubMed Central

    Berney, Michael; Greening, Chris; Conrad, Ralf; Jacobs, William R.; Cook, Gregory M.

    2014-01-01

    Oxygen availability is a major factor and evolutionary force determining the metabolic strategy of bacteria colonizing an environmental niche. In the soil, conditions can switch rapidly between oxia and anoxia, forcing soil bacteria to remodel their energy metabolism accordingly. Mycobacterium is a dominant genus in the soil, and all its species are obligate aerobes. Here we show that an obligate aerobe, the soil actinomycete Mycobacterium smegmatis, adopts an anaerobe-type strategy by activating fermentative hydrogen production to adapt to hypoxia. This process is controlled by the two-component system DosR-DosS/DosT, an oxygen and redox sensor that is well conserved in mycobacteria. We show that DosR tightly regulates the two [NiFe]-hydrogenases: Hyd3 (MSMEG_3931-3928) and Hyd2 (MSMEG_2719-2718). Using genetic manipulation and high-sensitivity GC, we demonstrate that Hyd3 facilitates the evolution of H2 when oxygen is depleted. Combined activity of Hyd2 and Hyd3 was necessary to maintain an optimal NAD+/NADH ratio and enhanced adaptation to and survival of hypoxia. We demonstrate that fermentatively-produced hydrogen can be recycled when fumarate or oxygen become available, suggesting Mycobacterium smegmatis can switch between fermentation, anaerobic respiration, and aerobic respiration. Hydrogen metabolism enables this obligate aerobe to rapidly meet its energetic needs when switching between microoxic and anoxic conditions and provides a competitive advantage in low oxygen environments. PMID:25049411

  5. An obligately aerobic soil bacterium activates fermentative hydrogen production to survive reductive stress during hypoxia.

    PubMed

    Berney, Michael; Greening, Chris; Conrad, Ralf; Jacobs, William R; Cook, Gregory M

    2014-08-01

    Oxygen availability is a major factor and evolutionary force determining the metabolic strategy of bacteria colonizing an environmental niche. In the soil, conditions can switch rapidly between oxia and anoxia, forcing soil bacteria to remodel their energy metabolism accordingly. Mycobacterium is a dominant genus in the soil, and all its species are obligate aerobes. Here we show that an obligate aerobe, the soil actinomycete Mycobacterium smegmatis, adopts an anaerobe-type strategy by activating fermentative hydrogen production to adapt to hypoxia. This process is controlled by the two-component system DosR-DosS/DosT, an oxygen and redox sensor that is well conserved in mycobacteria. We show that DosR tightly regulates the two [NiFe]-hydrogenases: Hyd3 (MSMEG_3931-3928) and Hyd2 (MSMEG_2719-2718). Using genetic manipulation and high-sensitivity GC, we demonstrate that Hyd3 facilitates the evolution of H2 when oxygen is depleted. Combined activity of Hyd2 and Hyd3 was necessary to maintain an optimal NAD(+)/NADH ratio and enhanced adaptation to and survival of hypoxia. We demonstrate that fermentatively-produced hydrogen can be recycled when fumarate or oxygen become available, suggesting Mycobacterium smegmatis can switch between fermentation, anaerobic respiration, and aerobic respiration. Hydrogen metabolism enables this obligate aerobe to rapidly meet its energetic needs when switching between microoxic and anoxic conditions and provides a competitive advantage in low oxygen environments. PMID:25049411

  6. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  8. 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.

  9. Standard of care of erectile dysfunction in U.S. Air Force aircrew and active duty not on flying status.

    PubMed

    Nast, Justin B

    2014-11-01

    In 2011, over 3,000 active duty U.S. Air Force (USAF) members were prescribed a phosphodiesterase inhibitor (PDEI). PDEIs are first-line therapy for treating erectile dysfunction and can have significant side effects that could impact aircrew performance. In total, 200 eligible subject records were randomly sampled from the active duty USAF population of those males filling a prescription for a PDEI in June 2011; 100 of those records were from aviators. The electronic records were reviewed and scored to determine if USAF aeromedical standards for prescribing PDEIs were followed, with a minimum score of 0 for no standards met and a maximum of 3 for all standards met. The average score for both groups was 1, with no significant difference between the group scores. A proper aeromedical disposition was documented in 67% of the aviator records. Although there was no significant difference in standard of care for aviators and nonaviators, the overall documented standard of care was poor. Lack of documentation was the primary reason for the low scores and the low percentage of properly rendered aeromedical dispositions. Proper medical record documentation is important for evaluating quality of care and ensuring compliance with regulations in an Air Force aviator population. PMID:25373059

  10. 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

  11. Update: Exertional rhabdomyolysis, active component, U.S. Army, Navy, Air Force, and Marine Corps, 2011-2015.

    PubMed

    2016-03-01

    Among active component members of the U.S. Army, Navy, Air Force, and Marine Corps in 2015, there were 456 incident episodes of rhabdomyolysis likely due to physical exertion or heat stress ("exertional rhabdomyolysis"). Annual rates of incident diagnoses of exertional rhabdomyolysis increased 17% between 2014 and 2015. In 2015, the highest incidence rates occurred in service members who were male; younger than 20 years of age; black, non-Hispanic; members of the Marine Corps and Army; recruit trainees; and in combat-specific occupations. Most cases of exertional rhabdomyolysis were diagnosed at installations that support basic combat/recruit training or major ground combat units of the Army or Marine Corps. Medical care providers should consider exertional rhabdomyolysis in the differential diagnosis when service members (particularly recruits) present with muscular pain and swelling, limited range of motion, or the excretion of dark urine (e.g., myoglobinuria) after strenuous physical activity, particularly in hot, humid weather. PMID:27030929

  12. Holocene canyon activity under a combination of tidal and tectonic forcing

    NASA Astrophysics Data System (ADS)

    Mountjoy, Joshu; Micallef, Aaron; Stevens, Craig; Stirling, Mark

    2013-04-01

    The majority of submarine canyon systems that are active during sea level highstands are coupled to terrestrial or littoral sediment transport systems (e.g. high sediment-yield rivers, wave-base sediment disturbance). However, non-coupled canyon systems can also exhibit sedimentary activity. Characterising the nature, origin, and spatial and temporal influence of the processes responsible for this sedimentary activity is important to understand the extent of sediment and carbon transfer to the deep sea, the impact of sedimentary flows on biological colonisation and diversity, and the control of recent seafloor processes on canyon morphology. The Cook Strait canyon system, between the North and South islands of New Zealand, is a large (1800 km2), multi-branching, shelf-indenting canyon on an active subduction margin. The canyon comes within 1 km of the coast, but does not intercept fluvial or littoral sediment systems and is therefore defined as a non-terrestrially-coupled system. Sediment transport on the continental shelf, associated with a strong tidal stream, and seafloor disturbance related to numerous high-activity faults is known from previous studies. Little is known, however, about the rates of sedimentary activity in the canyon and the processes driving it. The canyon system therefore provides an excellent study area for understanding sediment transport in a non-coupled submarine canyon system. Analysis of EM300 multibeam bathymetry, gravity cores, 3.5 kHz seismic reflection profiles, camera and video transects and current meter data reveals a system where oceanographic (tidal) and tectonic (earthquake) processes are moving sediment from the continental shelf, through the upper canyon, and finally to the deep ocean. Sediment accumulation rates may reach several mm/yr in the upper canyons, with data suggesting minimum rates of 0.5 mm/yr. We demonstrate that tidal currents are sufficient to mobilise fine to medium sand around and within the upper canyon

  13. Production of charcoal and activated carbon at elevated pressure

    SciTech Connect

    Dai, Xiangfeng; Norberg, N.; Antal, M.J. Jr.

    1995-12-31

    With its wide range of properties, charcoal finds many commercial applications for domestic cooking, refining of metals (steel, copper, bronze, nickel, aluminum and electro-manganese), production of chemicals (carbon disulfide, calcium carbide, silicon carbide, sodium cyanide, carbon black, fireworks, gaseous chemicals, absorbents, soil conditioners and pharmaceuticals), as well as production of activated carbon and synthesis gas. In 1991, the world production of charcoal was 22.8 million cubic meters (3.8 million metric tons) as shown in Table 1. Brazil is the world`s largest charcoal producer --- 5.9 million cubic meters or one million metric tons was produced in 1991, most of which is used in steel and iron industry. African countries produced 45% of the world total amount of charcoal, where 86% of the wood-based energy is for domestic use, most of which is inefficiently used. Charcoal is produced commercially in kilns with a 25% to 30% yield by mass on a 7 to 12 day operating cycle. Until recently, the highest yield of good quality charcoal reported in the literature was 38%. In this paper, and ASME code rated experimental system is presented for producing charcoal and activated carbon from biomass.

  14. Analysis of the swimming activity of Pseudomonas aeruginosa by using photonic force microscope

    NASA Astrophysics Data System (ADS)

    Chan, Chia-Han; Chang, Bo-Jui; Huang, Ying-Jung; Fan, Chia-Chieh; Peng, Hwei-Ling; Chi, Sien; Hsu, Long

    2005-08-01

    Swimming activity of flagella is a main factor of the motility of bacteria. Flagella expressed on the surface of bacterial species serve as a primary means of motility including swimming. We propose to use optical tweezers to analyze the swimming activity of bacteria. The sample bacteria in the work is Pseudomonas aeruginosa, and it is a gram-negative bacterium and often causes leading to burn wound infections, urinary-tract infections, and pneumonia. The single polar flagellum of P. aeruginosa has been demonstrated to be important virulence and colonization factor of this opportunistic pathogen. We demonstrate a gene to regulate the bacterial swimming activity in P. aeruginosa PAO1 by biological method. However, the change of flagellar morphology was not observed by electron microscopy analysis, suggesting that the gene regulates the flagellar rotation that could not be detected by biological method. PFM exhibits a spatial resolution of a few nanometers to detect the relative position of the probe at an acquisition rate over 1 MHz. By binding a probe such as a bead or a quantum dot on the flagella, we expect the rotation of the probe due to the flagella could be detected. It is expected that the study of the swimming activity of P. aeruginosa provide potent method for the pathogenic role of the flagella in P. aeruginosa.

  15. Analyzing Science Activities in Force and Motion Concepts: A Design of an Immersion Unit

    ERIC Educational Resources Information Center

    Ayar, Mehmet C.; Aydeniz, Mehmet; Yalvac, Bugrahan

    2015-01-01

    In this paper, we analyze the science activities offered at 7th grade in the Turkish science and technology curriculum along with addressing the curriculum's original intent. We refer to several science education researchers' ideas, including Chinn & Malhotra's (Science Education, 86:175--218, 2002) theoretical framework and…

  16. 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.

  17. Cluster Active Archive products and multipoint magnetospheric investigations

    NASA Astrophysics Data System (ADS)

    Perry, C.; Laakso, H.; Taylor, M.; Escoubet, P.

    2007-12-01

    The four-satellite Cluster mission investigates the small-scale structures (in three dimensions) of the Earth's plasma environment, such as those involved in the interaction between the solar wind and the magnetospheric plasma, in global magnetotail dynamics, in cross-tail currents, and in the formation and dynamics of the neutral line and of plasmoids. The Cluster Active Archive CAA (http://caa.estec.esa.int/) contains the entire set of Cluster high resolution data and other allied products in a standard format. The CAA currently has data from most of the Cluster instruments for at least the first three years of operations (2001-2003). The coverage and range of products is being continually improved with more than 200 datasets available from each spacecraft including high-resolution magnetic & electric DC fields and wave spectra; full 3D electron & ion distributions from a few eV to hundreds of keV; and various ancillary & browse products to help with spacecraft and event location. The data archived are (1) publicly accessible, (2) of the best quality achievable with the given resources, and (3) suitable for science use and publication by both the Cluster and broader scientific community. The presentation contains examples of user friendly services of the CAA for searching and accessing these data and ancillary products and of online capabilities of the system.

  18. Muscle Activation and Estimated Relative Joint Force During Running with Weight Support on a Lower-Body Positive-Pressure Treadmill.

    PubMed

    Jensen, Bente R; Hovgaard-Hansen, Line; Cappelen, Katrine L

    2016-08-01

    Running on a lower-body positive-pressure (LBPP) treadmill allows effects of weight support on leg muscle activation to be assessed systematically, and has the potential to facilitate rehabilitation and prevent overloading. The aim was to study the effect of running with weight support on leg muscle activation and to estimate relative knee and ankle joint forces. Runners performed 6-min running sessions at 2.22 m/s and 3.33 m/s, at 100%, 80%, 60%, 40%, and 20% body weight (BW). Surface electromyography, ground reaction force, and running characteristics were measured. Relative knee and ankle joint forces were estimated. Leg muscles responded differently to unweighting during running, reflecting different relative contribution to propulsion and antigravity forces. At 20% BW, knee extensor EMGpeak decreased to 22% at 2.22 m/s and 28% at 3.33 m/s of 100% BW values. Plantar flexors decreased to 52% and 58% at 20% BW, while activity of biceps femoris muscle remained unchanged. Unweighting with LBPP reduced estimated joint force significantly although less than proportional to the degree of weight support (ankle). It was concluded that leg muscle activation adapted to the new biomechanical environment, and the effect of unweighting on estimated knee force was more pronounced than on ankle force. PMID:26957520

  19. Turbokon scientific and production implementation company—25 years of activity

    NASA Astrophysics Data System (ADS)

    Favorskii, O. N.; Leont'ev, A. I.; Milman, O. O.

    2016-05-01

    The main results of studies performed at ZAO Turbokon NPVP in cooperation with leading Russian scientific organizations during 25 years of its activity in the field of development of unique ecologically clean electric power and heat production technologies are described. They include the development and experimental verification using prototypes and full-scale models of highly efficient air-cooled condensers for steam turbines, a high temperature gas steam turbine for stationary and transport power engineering, a nonfuel technology of electric power production using steam turbine installations with a unit power of 4-20 MW at gas-main pipelines and industrial boiler houses and heat stations. The results of efforts in the field of reducing vibroactivity of power equipment for transport installations are given. Basic directions of further research for increasing the efficiency and ecological safety of home power engineering are discussed.

  20. Production of biologically active recombinant human lactoferrin in Aspergillus oryzae.

    PubMed

    Ward, P P; Lo, J Y; Duke, M; May, G S; Headon, D R; Conneely, O M

    1992-07-01

    We report the production of recombinant human lactoferrin in Aspergillus oryzae. Expression of human lactoferrin (hLF), a 78 kD glycoprotein, was achieved by placing the cDNA under the control of the A. oryzae alpha-amylase promoter and the 3' flanking region of the A. niger glucoamylase gene. Using this system, hLF is expressed and secreted into the growth medium at levels up to 25 mg/l. The recombinant lactoferrin is indistinguishable from human milk lactoferrin with respect to its size, immunoreactivity, and iron-binding capacity. The recombinant protein appears to be appropriately N-linked glycosylated and correctly processed at the N-terminus by the A. oryzae secretory apparatus. Lactoferrin is the largest heterologous protein and the first mammalian glycoprotein expressed in the Aspergillus system to date. Hence, this expression system appears suitable for the large-scale production and secretion of biologically active mammalian glycoproteins. PMID:1368268

  1. Land processes distributed active archive center product lifecycle plan

    USGS Publications Warehouse

    Daucsavage, John C.; Bennett, Stacie D.

    2014-01-01

    The U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center and the National Aeronautics and Space Administration (NASA) Earth Science Data System Program worked together to establish, develop, and operate the Land Processes (LP) Distributed Active Archive Center (DAAC) to provide stewardship for NASA’s land processes science data. These data are critical science assets that serve the land processes science community with potential value beyond any immediate research use, and therefore need to be accounted for and properly managed throughout their lifecycle. A fundamental LP DAAC objective is to enable permanent preservation of these data and information products. The LP DAAC accomplishes this by bridging data producers and permanent archival resources while providing intermediate archive services for data and information products.

  2. Production of carboxylates from high rate activated sludge through fermentation.

    PubMed

    Cagnetta, C; Coma, M; Vlaeminck, S E; Rabaey, K

    2016-10-01

    The aim of this work was to study the key parameters affecting fermentation of high rate activated A-sludge to carboxylates, including pH, temperature, inoculum, sludge composition and iron content. The maximum volatile fatty acids production was 141mgCg(-1) VSSfed, at pH 7. Subsequently the potential for carboxylate and methane production for A-sludge from four different plants at pH 7 and 35°C were compared. Initial BOD of the sludge appeared to be key determining carboxylate yield from A-sludge. Whereas methanogenesis could be correlated linearly to the quantity of ferric used for coagulation, fermentation did not show a dependency on iron presence. This difference may enable a strategy whereby A-stage sludge is separated to achieve fermentation, and iron dosing for phosphate removal is only implemented at the B-stage. PMID:27020399

  3. Autonomic control of heart rate during forced activity and digestion in the snake Boa constrictor.

    PubMed

    Wang, T; Taylor, E W; Andrade, D; Abe, A S

    2001-10-01

    Reptiles, particularly snakes, exhibit large and quantitatively similar increments in metabolic rate during muscular exercise and following a meal, when they are apparently inactive. The cardiovascular responses are similar during these two states, but the underlying autonomic control of the heart remains unknown. We describe both adrenergic and cholinergic tonus on the heart during rest, during enforced activity and during digestion (24-36 h after ingestion of 30 % of their body mass) in the snake Boa constrictor. The snakes were equipped with an arterial catheter for measurements of blood pressure and heart rate, and autonomic tonus was determined following infusion of the beta-adrenergic antagonist propranolol (3 mg kg(-1)) and the muscarinic cholinoceptor antagonist atropine (3 mg kg(-1)). The mean heart rate of fasting animals at rest was 26.4+/-1.4 min(-1), and this increased to 36.1+/-1.4 min(-1) (means +/- S.E.M.; N=8) following double autonomic block (atropine and propranolol). The calculated cholinergic and adrenergic tones were 60.1+/-9.3 % and 19.8+/-2.2 %, respectively. Heart rate increased to 61.4+/-1.5 min(-1) during enforced activity, and this response was significantly reduced by propranolol (maximum values of 35.8+/-1.6 min(-1)), but unaffected by atropine. The cholinergic and adrenergic tones were 2.6+/-2.2 and 41.3+/-1.9 % during activity, respectively. Double autonomic block virtually abolished tachycardia associated with enforced activity (heart rate increased significantly from 36.1+/-1.4 to 37.6+/-1.3 min(-1)), indicating that non-adrenergic, non-cholinergic effectors are not involved in regulating heart rate during activity. Blood pressure also increased during activity. Digestion was accompanied by an increase in heart rate from 25.6+/-1.3 to 47.7+/-2.2 min(-1) (N=8). In these animals, heart rate decreased to 44.2+/-2.7 min(-1) following propranolol infusion and increased to 53.9+/-1.8 min(-1) after infusion of atropine, resulting in small

  4. Aerosol Precursor Emissions, Secondary Aerosol Production, and Climate-Forcing Gas Exchange in the Midwestern United States

    NASA Astrophysics Data System (ADS)

    Doskey, P. V.

    2009-12-01

    Aerosol precursors in the Midwest are generated from a myriad of sources including biogenic emissions of terpenes from the Ozarks region, anthropogenic emissions of volatile and semivolatile aliphatic and aromatic hydrocarbons from the St. Louis airshed, and agricultural emissions of ammonia (NH3), amines, and nitrogen oxides (NOx) from animal husbandry and cropping systems of the Midwest Corn Belt. The deciduous and coniferous forests of the Ozarks region are significant sources of isoprene, monoterpenes, and sesquiterpenes that are sensitive to rising CO2 levels and temperature and generate light-scattering, secondary organic aerosol (SOA). Application of nitrogen fertilizers stimulates emissions of ammonia (NH3), nitric oxide (NO), and nitrous oxide (N2O) from agricultural soils and crops. Nitric acid, generated through photooxidation of NO emissions from fossil fuel combustion in urban air and from soil emissions in agroecosystems, reacts rapidly with NH3 to generate light-scattering, secondary inorganic aerosol (SIA). The atmospheric lifetime of N2O is about 120 years, making the substance a potent greenhouse gas with a global warming potential of 290 for a time horizon of 20 years relative to CO2. Emissions of CO2, N2O, and SIA precursors from the Midwest Corn Belt and surrounding areas are likely to increase in the near future as pastureland and prairie is converted to grow corn and other biofuel crops to meet the demand for renewable fuels. Several large river systems transport nutrients from fertilized fields of the Midwest agroecosystem to the Gulf of Mexico where plankton growth is accelerated. Microbial decomposition of plankton detritus consumes oxygen and creates a hypoxic zone, which might be a significant source of N2O.The presentation will discuss gaps in our knowledge of the production of climate-forcing species in the Midwestern United States.

  5. Comparison of muscle force production using the Smith machine and free weights for bench press and squat exercises.

    PubMed

    Cotterman, Michael L; Darby, Lynn A; Skelly, William A

    2005-02-01

    The Smith machine (SM) (vertical motion of bar on fixed path; fixed-form exercise) and free weights (FWs) (free-form path) are commonly used strength training modes. Exercisers may need to alternate between types of equipment, depending on testing, training, rehabilitation, and/or the exercisers' goals. The purposes of this study were to compare muscle force production for SM and FWs using a 1 repetition maximum (1RM) for the parallel back squat and supine bench press exercises and to predict the 1RM for one mode from 1RM on the other mode. Men (n = 16) and women (n = 16) alternately completed 1RM testing for squat and bench press using SM and FWs. Analyses of variance (type of equipment x sex) and linear regression models were calculated. A significant difference was found between bench press and squat 1RMs for each mode of equipment for all participants. The squat 1RM was greater for the SM than the FWs; conversely, the bench 1RM was greater for FWs than the SM. When sex was considered, bench 1RM for FWs was greater than SM for men and women. The squat 1RM was greater for SM than FWs for women only. The 1RM on one mode of equipment was the best predictor of 1RM for the other mode. For both sexes, the equation SM bench 1RM (in kilograms) = -6.76 + 0.95 (FW bench 1RM) can be used. For women only, SM squat 1RM (in kilograms) = 28.3 + 0.73 (FW squat 1RM). These findings provide equations for converting between SM and FW equipment for training. PMID:15705030

  6. Natural products from cyanobacteria with antimicrobial and antitumor activity.

    PubMed

    Silva-Stenico, Maria Estela; Kaneno, Ramon; Zambuzi, Fabiana Albani; Vaz, Marcelo G M V; Alvarenga, Danillo O; Fiore, Marli Fátima

    2013-01-01

    Cyanobacteria are an important source of structurally bioactive metabolites, with cytotoxic, antiviral, anticancer, antimitotic, antimicrobial, specific enzyme inhibition and immunosuppressive activities. This study focused on the antitumor and antimicrobial activities of intra and extracellular cyanobacterial extracts. A total of 411 cyanobacterial strains were screened for antimicrobial activity using a subset of pathogenic bacteria as target. The in vitro antitumor assays were performed with extracts of 24 strains tested against two murine cancer cell lines (colon carcinoma CT-26 and lung cancer 3LL). Intracellular extracts inhibited 49 and 35% of Gram-negative and Gram-positive pathogenic bacterial growth, respectively. Furthermore, the methanolic intracellular extract of Cylindrospermopsis raciborskii CYP011K and Nostoc sp. CENA69 showed inhibitory activity against the cancer cell lines. The extracellular extract from Fischerella sp. CENA213 and M. aeruginosa NPJB-1 exhibited inhibitory activity against 3LL lung cancer cells at 0.8 µg ml⁻¹ and Oxynema sp. CENA135, Cyanobium sp. CENA154, M. aeruginosa NPJB-1 and M. aeruginosa NPLJ-4 presented inhibitory activity against CT26 colon cancer cells at 0.8 µg ml⁻¹. Other extracts were able to inhibit 3LL cell-growth at higher concentrations (20 µg ml⁻¹) such as Nostoc sp. CENA67, Cyanobium sp. CENA154 and M. aeruginosa NPLJ-4, while CT26 cells were inhibited at the same concentration by Nostoc sp. CENA67 and Fischerella sp. CENA213. These extracts presented very low inhibitory activity on human peripheral blood lymphocytes. The results showed that some cyanobacterial strains are a rich source of natural products with potential for pharmacological and biotechnological applications. PMID:24372264

  7. Paralleling power MOSFETs in their active region: Extended range of passively forced current sharing

    NASA Technical Reports Server (NTRS)

    Niedra, Janis M.

    1989-01-01

    A simple passive circuit that improves current balance in parallelled power MOSFETs that are not precisely matched and that are operated in their active region from a common gate drive are exhibited. A nonlinear circuit consisting of diodes and resistors generates the differential gate potential required to correct for unbalance while maintaining low losses over a range of current. Also application of a thin tape wound magnetic core to effect dynamic current balance is reviewed, and a simple theory is presented showing that for operation in the active region the branch currents tend to revert to their normal unbalanced values even if the core is not driven into saturation. Results of several comparative experiments are given.

  8. 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.

  9. Method and Apparatus for Monitoring of Daily Activity in Terms of Ground Reaction Forces

    NASA Technical Reports Server (NTRS)

    Whalen, Robert T. (Inventor); Breit, Gregory A. (Inventor)

    2001-01-01

    A device to record and analyze habitual daily activity in terms of the history of gait-related musculoskeletal loading is disclosed. The device consists of a pressure-sensing insole placed into the shoe or embedded in a shoe sole, which detects contact of the foot with the ground. The sensor is coupled to a portable battery-powered digital data logger clipped to the shoe or worn around the ankle or waist. During the course of normal daily activity, the system maintains a record of time-of-occurrence of all non-spurious foot-down and lift-off events. Off line, these data are filtered and converted to a history of foot-ground contact times, from which measures of cumulative musculoskeletal loading, average walking- and running-specific gait speed, total time spent walking and running, total number of walking steps and running steps, and total gait-related energy expenditure are estimated from empirical regressions of various gait parameters to the contact time reciprocal. Data are available as cumulative values or as daily averages by menu selection. The data provided by this device are useful for assessment of musculoskeletal and cardiovascular health and risk factors associated with habitual patterns of daily activity.

  10. Presence and biological activity of antibiotics used in fuel ethanol and corn co-product production.

    PubMed

    Compart, D M Paulus; Carlson, A M; Crawford, G I; Fink, R C; Diez-Gonzalez, F; Dicostanzo, A; Shurson, G C

    2013-05-01

    Antibiotics are used in ethanol production to control bacteria from competing with yeast for nutrients during starch fermentation. However, there is no published scientific information on whether antibiotic residues are present in distillers grains (DG), co-products from ethanol production, or whether they retain their biological activity. Therefore, the objectives of this study were to quantify concentrations of various antibiotic residues in DG and determine whether residues were biologically active. Twenty distillers wet grains and 20 distillers dried grains samples were collected quarterly from 9 states and 43 ethanol plants in the United States. Samples were analyzed for DM, CP, NDF, crude fat, S, P, and pH to describe the nutritional characteristics of the samples evaluated. Samples were also analyzed for the presence of erythromycin, penicillin G, tetracycline, tylosin, and virginiamycin M1, using liquid chromatography and mass spectrometry. Additionally, virginiamycin residues were determined, using a U.S. Food and Drug Administration-approved bioassay method. Samples were extracted and further analyzed for biological activity by exposing the sample extracts to 10(4) to 10(7) CFU/mL concentrations of sentinel bacterial strains Escherichia coli ATCC 8739 and Listeria monocytogenes ATCC 19115. Extracts that inhibited bacterial growth were considered to have biological activity. Physiochemical characteristics varied among samples but were consistent with previous findings. Thirteen percent of all samples contained low (≤1.12 mg/kg) antibiotic concentrations. Only 1 sample extract inhibited growth of Escherichia coli at 10(4) CFU/mL, but this sample contained no detectable concentrations of antibiotic residues. No extracts inhibited Listeria monocytogenes growth. These data indicate that the likelihood of detectable concentrations of antibiotic residues in DG is low; and if detected, they are found in very low concentrations. The inhibition in only 1 DG

  11. Neutron Activation Analysis and Product Isotope Inventory Code System.

    1990-10-31

    Version 00 NAC was designed to predict the neutron-induced gamma-ray radioactivity for a wide variety of composite materials. The NAC output includes the input data, a list of all reactions for each constituent element, and the end-of-irradiation disintegration rates for each reaction. NAC also compiles a product isotope inventory containing the isotope name, the disintegration rate, the gamma-ray source strength, and the absorbed dose rate at 1 meter from an unshielded point source. The inducedmore » activity is calculated as a function of irradiation and decay times; the effect of cyclic irradiation can also be calculated.« less

  12. Activation patterns of mono- and bi-articular arm muscles as a function of force and movement direction of the wrist in humans

    PubMed Central

    van Bolhuis, B M; Gielen, C C A M; van Ingen Schenau, G J

    1998-01-01

    In order to explain the task-dependent activation of muscles, we have investigated the hypothesis that mono- and bi-articular muscles have a different functional role in the control of multijoint movements. According to this hypothesis, bi-articular muscles are activated in a way to control the direction of external force. The mono-articular muscles are thought to be activated to contribute to joint torque mainly during shortening movements.To investigate this hypothesis, surface electromyographic (EMG) recordings were obtained from several mono- and bi-articular arm muscles during voluntary slow movements of the wrist in a horizontal plane against an external force. The direction of force produced at the wrist and the direction of movement of the wrist were varied independently.The results revealed distinct differences between the activation patterns of mono- and bi-articular muscles. The activation of the bi-articular muscles was not affected by movement direction, but appeared to vary exclusively with the direction of force.The mono-articular muscles showed significantly more EMG activity for movements in a specific direction, which equalled the movement direction corresponding to the largest shortening velocity of the muscle. The EMG activity decreased gradually for movements in other directions. This direction-dependent activation appeared to be independent of the direction of the external force. PMID:9490859

  13. Climate Forcing of North Atlantic Tropical Cyclone Activity over the last 6000 years

    NASA Astrophysics Data System (ADS)

    Donnelly, J. P.; Woodruff, J. D.; Scileppi, E.; Lane, P.

    2006-12-01

    Reconstructions of extreme overwash events in backbarrier lagoons and wetlands from the Caribbean to the northeastern United States show similar patterns of event occurrence. Comparisons with instrumental and historical records indicate that most of these overwash layers were likely deposited by landfalling tropical cyclones. Over the last 6000 years intense tropical cyclones have deposited coarse grained laminae in a coastal lagoon on Vieques, Puerto Rico. Intervals with more frequent intense tropical cyclone strikes occurred at 5600-4200 years ago, 2500-1000 years ago, and 250 years ago to present. Similarly records from backbarrier wetlands in the New York/New Jersey Bight provide evidence of more frequent overwash in the last 300 years and 2200 to 900 years ago. An earlier active interval in New York is also evident and dates to sometime before 2700 years ago. Other shorter records from the northeastern United States also provide evidence of more frequent storm-induced deposition over the last few hundred years following a relative lull in overwash and presumably tropical cyclone landfalls. This increase in tropical cyclone landfalls occurs during the later half of the Little Ice Age (LIA) when sea surface temperatures (SSTs) in the tropics were 2-3°C cooler than modern. Over the last several millennia a coherent pattern of climate change appears to have modulated intense tropical cyclone activity in the North Atlantic. The evolution of El Niño/Southern Oscillation (ENSO) variability over the late Holocene likely played an important role in controlling the frequency of intense tropical cyclones in the entire North Atlantic Basin, with intervals of fewer strong El Niño events being more favorable to intense tropical cyclone activity. In addition, variations in the West African monsoon, possibly tied to ENSO, may be an important control on the frequency of North Atlantic intense tropical cyclones. With increases in intense convective storms over tropical

  14. Natural Product Nitric Oxide Chemistry: New Activity of Old Medicines

    PubMed Central

    Jiang, Hong; Torregrossa, Ashley C.; Parthasarathy, Deepa K.; Bryan, Nathan S.

    2012-01-01

    The use of complementary and alternative medicine (CAM) as a therapy and preventative care measure for cardiovascular diseases (CVD) may prove to be beneficial when used in conjunction with or in place of conventional medicine. However, the lack of understanding of a mechanism of action of many CAMs limits their use and acceptance in western medicine. We have recently recognized and characterized specific nitric oxide (NO) activity of select alternative and herbal medicines that may account for many of their reported health benefits. The ability of certain CAM to restore NO homeostasis both through enhancing endothelial production of NO and by providing a system for reducing nitrate and nitrite to NO as a compensatory pathway for repleting NO bioavailability may prove to be a safe and cost-effective strategy for combating CVD. We will review the current state of science behind NO activity of herbal medicines and their effects on CVD. PMID:22548122

  15. Statistical study of free magnetic energy and flare productivity of solar active regions

    SciTech Connect

    Su, J. T.; Jing, J.; Wang, S.; Wang, H. M.; Wiegelmann, T.

    2014-06-20

    Photospheric vector magnetograms from the Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory are utilized as the boundary conditions to extrapolate both nonlinear force-free and potential magnetic fields in solar corona. Based on the extrapolations, we are able to determine the free magnetic energy (FME) stored in active regions (ARs). Over 3000 vector magnetograms in 61 ARs were analyzed. We compare FME with the ARs' flare index (FI) and find that there is a weak correlation (<60%) between FME and FI. FME shows slightly improved flare predictability relative to the total unsigned magnetic flux of ARs in the following two aspects: (1) the flare productivity predicted by FME is higher than that predicted by magnetic flux and (2) the correlation between FI and FME is higher than that between FI and magnetic flux. However, this improvement is not significant enough to make a substantial difference in time-accumulated FI, rather than individual flare, predictions.

  16. 78 FR 39254 - Notification of Proposed Production Activity; Subzone 7G; Schering-Plough Products, L.L.C...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-01

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE Foreign-Trade Zones Board Notification of Proposed Production Activity; Subzone 7G; Schering-Plough Products, L.L.C. (Pharmaceutical Products); Las Piedras, Puerto Rico Schering-Plough Products, L.L.C. (Schering-Plough), operator of Subzone 7G,...

  17. The effect of inquiry science activity in educational productivity

    NASA Astrophysics Data System (ADS)

    Shimizu, Kinya

    This is a study the effect of inquiry science activity on the science achievement of junior high school students. Since the post-sputnik curriculum improvement project, science educators have supported the effect of inquiry activities. In terms of the effect of laboratory activity, however, the literature review indicated that the controlled experimental studies have failed to present the effect of laboratory activities. For example, Blosser suggested more rigid experimental design, such as longer treatment and larger sample. On the other hand, some of the recent case studies of effect of laboratory are successful to support the effect and the other recent classroom ethnographic studies indicated that the laboratory activities are implemented in inappropriate situation. This study investigates the effect of inquiry activities by using the national survey to balance the internal and external validity. In order to control the environmental effect and student aptitude, the study adopted the structural model of science achievement suggested by Reynolds and Walberg in 1991. The study utilized the extensive student and teacher data reports from the Longitudinal Study of American Youth (LSAY) to examine these differences and interactions quantitatively. The study utilized two independent variables: (1) teachers' report of the degree of their teaching emphasis on inquiry skill, and (2) teachers' report of the frequency of hands-on method. The effects of these instructional qualities are estimated in terms of the science achievement score of their student. The study utilized path analysis techniques in order to understand the complex relationship among the nine productivity factors; which are (1) motivation, (2) prior ability, (3) development, (4) home environment, (5) peer environment, (6) media environment, (7) classroom environment, (8) instructional quantity, and (9) instructional quality. The result failed to support the effectiveness of the hands-on science teaching

  18. Stimulation of Na(+),K(+)-ATPase Activity as a Possible Driving Force in Cholesterol Evolution.

    PubMed

    Lambropoulos, Nicholas; Garcia, Alvaro; Clarke, Ronald J

    2016-06-01

    Cholesterol is exclusively produced by animals and is present in the plasma membrane of all animal cells. In contrast, the membranes of fungi and plants contain other sterols. To explain the exclusive preference of animal cells for cholesterol, we propose that cholesterol may have evolved to optimize the activity of a crucial protein found in the plasma membrane of all multicellular animals, namely the Na(+),K(+)-ATPase. To test this hypothesis, mirror tree and phylogenetic distribution analyses have been conducted of the Na(+),K(+)-ATPase and 3β-hydroxysterol Δ(24)-reductase (DHCR24), the last enzyme in the Bloch cholesterol biosynthetic pathway. The results obtained support the hypothesis of a co-evolution of the Na(+),K(+)-ATPase and DHCR24. The evolutionary correlation between DHCR24 and the Na(+),K(+)-ATPase was found to be stronger than between DHCR24 and any other membrane protein investigated. The results obtained, thus, also support the hypothesis that cholesterol evolved together with the Na(+),K(+)-ATPase in multicellular animals to support Na(+),K(+)-ATPase activity. PMID:26715509

  19. Critical speeds and forced response solutions for active magnetic bearing turbomachinery, part 2

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    The need for better performance of turbomachinery with active magnetic bearings has necessitated a study of such systems for accurate prediction of their vibrational characteristics. A modification of existing transfer matrix methods for rotor analysis is presented to predict the response of rotor systems with active magnetic bearings. The position of the magnetic bearing sensors is taken into account and the effect of changing sensor position on the vibrational characteristics of the rotor system is studied. The modified algorithm is validated using a simpler Jeffcott model described previously. The effect of changing from a rotating unbalance excitation to a constant excitation in a single plane is also studied. A typical eight stage centrifugal compressor rotor is analyzed using the modified transfer matrix code. The results for a two mass Jeffcott model were presented previously. The results obtained by running this model with the transfer matrix method were compared with the results of the Jeffcott analysis for the purposes of verification. Also included are plots of amplitude versus frequency for the eight stage centrifugal compressor rotor. These plots demonstrate the significant influence that sensor location has on the amplitude and critical frequencies of the rotor system.

  20. Injuries associated with combat sports, active component, U.S. Armed Forces, 2010-2013.

    PubMed

    2014-05-01

    The practice of combat sports creates a potential for training- and sports-related injuries among military members. During the 4-year surveillance period, there were 12,108 cases of injuries associated with combat sports among active component service members; the overall incidence rate was 21.0 per 10,000 person-years (p-yrs). The rates were higher among service members who were male, Hispanic, in the youngest age groups, in the Army, junior enlisted, and in combat-specific occupations. The rate among recruit/ trainees (779.4 per 10,000 p-yrs) was more than 165 times the rate among all other active component service members (non-recruits) (4.7 per 10,000 p-yrs). Sprains, strains, and contusions accounted for more than one-half of the primary (first-listed) diagnoses associated with combat sports cases. More serious conditions such as concussions/head injuries and skull/face fractures/intracranial injuries were reported among 3.9% and 2.1% of all cases and were more common among boxing-related cases. Hand/wrist fractures were also common among boxing cases. Wrestling had comparatively greater proportions of dislocations and open wounds. Although the combat sport training provides many physical and mental benefits to the individual, safety practices should be enforced to reduce the most frequent and serious injuries. PMID:24885879

  1. 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

  2. Post-refractive surgery complications and eye disease, active component, U.S. Armed Forces, 2005-2014.

    PubMed

    Blitz, Jason B; Hunt, Devin J; Cost, Angelia A

    2016-05-01

    Refractive surgery (RS) is a common procedure in the U.S. military population. This report provides an estimation of incident RS for vision correction purposes in the active component of the U.S. military from 1 January 2005 through 31 December 2014 and the prevalence of post-RS complications and eye disease in the 1-year period after RS. During the surveillance period, a total of 121,571 subjects without a diagnosis of eye disease other than hyperopia, myopia, or astigmatism in the previous year received a single incident RS procedure. In the 1-year period after RS, 5.3% of subjects with preoperative hyperopia or myopia had treatment-persistent (unresolved) hyperopia or myopia; 2.0% of subjects with preoperative astigmatism had treatment-persistent (unresolved) astigmatism; and 3.8% were diagnosed with tear film insufficiency. In general, most outcomes showed higher prevalences in Army and Air Force personnel versus Navy and Marine Corps personnel, in women versus men, in officer versus enlisted personnel, and in aviation and Special Forces personnel. A wide variation in outcome prevalences was noted by procedural military treatment facility. PMID:27255946

  3. An Update on Natural Products with Carbonic Anhydrase Inhibitory Activity.

    PubMed

    Karioti, Anastasia; Carta, Fabrizio; Supuran, Claudiu T

    2016-01-01

    Carbonic anhydrases (CAs, EC 4.2.1.1) catalyze the fundamental reaction of CO2 hydration in all living organisms, being actively involved in the regulation of a plethora of patho/physiological processes. They represent a typical example of enzyme convergent evolution, as six genetically unrelated families of such enzymes were described so far. It is more than 70 years that synthetic compounds, mainly sulfonamides, have been used in clinical practice as diuretics and systemic acting antiglaucoma drugs. Recent studies using natural product libraries and isolated constituents from natural sources (such as fungi and plants) have disclosed novel chemotypes possessing carbonic anhydrase inhibition activities. These natural sources offer new opportunities in the search for new and more effective carbonic anhydrase inhibitors, and may serve as new leads for the design and development of future drugs. This review will discuss the most recent advances in the search of naturally occurring products and their synthetic derivatives that inhibit the CAs and their mechanisms of action at molecular level. Plant extracts are not considered in the present review. PMID:26654592

  4. Cold weather injuries, active and reserve components, U.S. Armed Forces, July 2008-June 2013.

    PubMed

    2013-10-01

    From July 2012 through June 2013, the number of active and reserve component service members treated for cold injuries (n=479) was the lowest of the last five cold seasons (2008-2013). Over the last five years hypothermia was the most common cold injury among service members in the Marine Corps and Coast Guard, while frostbite was the most common type of cold injury in the other three Services. Consistent with trends from previous cold seasons, service members who were female, less than 20 years old, or of black, non-Hispanic race/ethnicity tended to have higher cold injury rates than their respective counterparts. Among service members overall, Army personnel accounted for the majority (62%) of cold injuries. PMID:24191768

  5. Thyroid disorders among active component military members, U.S. Armed Forces, 2002-2011.

    PubMed

    2012-10-01

    During 2002-2011, among active component U.S. military members, the rates of idiopathic hypothyroidism were 39.7 and 7.8 per 10,000 person-years among females and males, respectively. Unadjusted rates of idiopathic hypothyroidism and chronic thyroiditis (e.g., Hashimoto's disease) were at least twice as high among white, non-Hispanic as black, non-Hispanic service members. However, black, non-Hispanic service members had higher rates of goiter and thyrotoxicosis. Increasing rates of thyroid disorders during the period were accompanied by increases in numbers of screening tests for thyroid function recorded during outpatient visits. Increased thyroid function testing since the beginning of the wars in Iraq and Afghanistan may reflect increased testing of military members with mental disorders (e.g., depression, irritability, PTSD), musculoskeletal pain, sleep disorders, menstrual/fertility abnormalities, obesity, and other conditions which have sharply increased in prevalence over the same period. PMID:23121006

  6. Recent changes in the climate: natural or forced by human activity?

    PubMed

    Karlén, Wibjörn

    2008-11-01

    Humanity has always lived under the threat of disasters such as famine. Now that these threats have diminished considerably in the West, it seems like people need a new scare that can be shared, thereby having a uniting effect. The possible impact of an increased atmospheric greenhouse gas concentration seems to have taken over this role. However, new dating techniques and numerous new studies have now added information that can bring about a reevaluation of the opinion that it is only human activity that can explain recent climatic changes. A distinction between trends and variability in climate is only possible if long-term records can be studied. Greenland ice core data yield well-dated information about climate over an extended period that, seen together with other data series, indicates that large, probably global scale changes have occurred at numerous times in the past. The warming during the past 100 y is not likely to be unique. PMID:19205124

  7. Sustainable production of biologically active molecules of marine based origin.

    PubMed

    Murray, Patrick M; Moane, Siobhan; Collins, Catherine; Beletskaya, Tanya; Thomas, Olivier P; Duarte, Alysson W F; Nobre, Fernando S; Owoyemi, Ifeloju O; Pagnocca, Fernando C; Sette, L D; McHugh, Edward; Causse, Eric; Pérez-López, Paula; Feijoo, Gumersindo; Moreira, Ma T; Rubiolo, Juan; Leirós, Marta; Botana, Luis M; Pinteus, Susete; Alves, Celso; Horta, André; Pedrosa, Rui; Jeffryes, Clayton; Agathos, Spiros N; Allewaert, Celine; Verween, Annick; Vyverman, Wim; Laptev, Ivan; Sineoky, Sergei; Bisio, Angela; Manconi, Renata; Ledda, Fabio; Marchi, Mario; Pronzato, Roberto; Walsh, Daniel J

    2013-09-25

    The marine environment offers both economic and scientific potential which are relatively untapped from a biotechnological point of view. These environments whilst harsh are ironically fragile and dependent on a harmonious life form balance. Exploitation of natural resources by exhaustive wild harvesting has obvious negative environmental consequences. From a European industry perspective marine organisms are a largely underutilised resource. This is not due to lack of interest but due to a lack of choice the industry faces for cost competitive, sustainable and environmentally conscientious product alternatives. Knowledge of the biotechnological potential of marine organisms together with the development of sustainable systems for their cultivation, processing and utilisation are essential. In 2010, the European Commission recognised this need and funded a collaborative RTD/SME project under the Framework 7-Knowledge Based Bio-Economy (KBBE) Theme 2 Programme 'Sustainable culture of marine microorganisms, algae and/or invertebrates for high value added products'. The scope of that project entitled 'Sustainable Production of Biologically Active Molecules of Marine Based Origin' (BAMMBO) is outlined. Although the Union is a global leader in many technologies, it faces increasing competition from traditional rivals and emerging economies alike and must therefore improve its innovation performance. For this reason innovation is placed at the heart of a European Horizon 2020 Strategy wherein the challenge is to connect economic performance to eco performance. This article provides a synopsis of the research activities of the BAMMBO project as they fit within the wider scope of sustainable environmentally conscientious marine resource exploitation for high-value biomolecules. PMID:23563183

  8. Forced expression of stabilized c-Fos in dendritic cells reduces cytokine production and immune responses in vivo

    SciTech Connect

    Yoshida, Ryoko; Suzuki, Mayu; Sakaguchi, Ryota; Hasegawa, Eiichi; Kimura, Akihiro; Shichita, Takashi; Sekiya, Takashi; Shiraishi, Hiroshi; Shimoda, Kouji; Yoshimura, Akihiko

    2012-06-29

    Highlights: Black-Right-Pointing-Pointer Dendritic cells expressing stabilized c-Fos produced less inflammatory cytokines. Black-Right-Pointing-Pointer Dendritic cells expressing stabilized c-Fos activated T cells less efficiently. Black-Right-Pointing-Pointer Transgenic mice expressing stabilized c-Fos were resistant to EAE model. -- Abstract: Intracellular cyclic adenosine monophosphate (cAMP) suppresses innate immunity by inhibiting proinflammatory cytokine production by monocytic cells. We have shown that the transcription factor c-Fos is responsible for cAMP-mediated suppression of inflammatory cytokine production, and that c-Fos protein is stabilized by IKK{beta}-mediated phosphorylation. We found that S308 is one of the major phosphorylation sites, and that the S308D mutation prolongs c-Fos halflife. To investigate the role of stabilized c-Fos protein in dendritic cells (DCs) in vivo, we generated CD11c-promoter-deriven c-FosS308D transgenic mice. As expected, bone marrow-derived DCs (BMDCs) from these Tg mice produced smaller amounts of inflammatory cytokines, including TNF-{alpha}, IL-12, and IL-23, but higher levels of IL-10, in response to LPS, than those from wild-type (Wt) mice. When T cells were co-cultured with BMDCs from Tg mice, production of Th1 and Th17 cytokines was reduced, although T cell proliferation was not affected. Tg mice demonstrated more resistance to experimental autoimmune encephalomyelitis (EAE) than did Wt mice. These data suggest that c-Fos in DCs plays a suppressive role in certain innate and adaptive immune responses.

  9. Investigation of the binding modes between AIE-active molecules and dsDNA by single molecule force spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Ying; Ma, Ke; Hu, Ting; Jiang, Bo; Xu, Bin; Tian, Wenjing; Sun, Jing Zhi; Zhang, Wenke

    2015-05-01

    AIE (aggregation-induced emission)-active molecules hold promise for the labeling of biomolecules as well as living cells. The study of the binding modes of such molecules to biomolecules, such as nucleic acids and proteins, will shed light on a deeper understanding of the mechanisms of molecular interactions and eventually facilitate the design/preparation of new AIE-active bioprobes. Herein, we studied the binding modes of double-stranded DNA (dsDNA) with two types of synthetic AIE-active molecules, namely, tetraphenylethene-derived dicationic compounds (cis-TPEDPy and trans-TPEDPy) and anthracene-derived dicationic compounds (DSAI and DSABr-C6) using single molecule force spectroscopy (SMFS) and circular dichroism (CD) spectroscopy. The experimental data indicate that DSAI can strongly intercalate into DNA base pairs, while DSABr-C6 is unable to intercalate into DNA due to the steric hindrance of the alkyl side chains. Cis-TPEDPy and trans-TPEDPy can also intercalate into DNA base pairs, but the binding shows strong ionic strength dependence. Multiple binding modes of TPEDPy with dsDNA have been discussed. In addition, the electrostatic interaction enhanced intercalation of cis-TPEDPy with dsDNA has also been revealed.AIE (aggregation-induced emission)-active molecules hold promise for the labeling of biomolecules as well as living cells. The study of the binding modes of such molecules to biomolecules, such as nucleic acids and proteins, will shed light on a deeper understanding of the mechanisms of molecular interactions and eventually facilitate the design/preparation of new AIE-active bioprobes. Herein, we studied the binding modes of double-stranded DNA (dsDNA) with two types of synthetic AIE-active molecules, namely, tetraphenylethene-derived dicationic compounds (cis-TPEDPy and trans-TPEDPy) and anthracene-derived dicationic compounds (DSAI and DSABr-C6) using single molecule force spectroscopy (SMFS) and circular dichroism (CD) spectroscopy. The

  10. Thrombin stimulates fibroblast procollagen production via proteolytic activation of protease-activated receptor 1.

    PubMed Central

    Chambers, R C; Dabbagh, K; McAnulty, R J; Gray, A J; Blanc-Brude, O P; Laurent, G J

    1998-01-01

    Thrombin is a multifunctional serine protease that has a crucial role in blood coagulation. It is also a potent mesenchymal cell mitogen and chemoattractant and might therefore have an important role in the recruitment and local proliferation of mesenchymal cells at sites of tissue injury. We hypothesized that thrombin might also affect the deposition of connective tissue proteins at these sites by directly stimulating fibroblast procollagen production. To address this hypothesis, the effect of thrombin on procollagen production and gene expression by human foetal lung fibroblasts was assessed over 48 h. Thrombin stimulated procollagen production at concentrations of 1 nM and above, with maximal increases of between 60% and 117% at 10 nM thrombin. These effects of thrombin were, at least in part, due to increased steady-state levels of alpha1(I) procollagen mRNA. They could furthermore be reproduced with thrombin receptor-activating peptides for the protease-activated receptor 1 (PAR-1) and were completely abolished when thrombin was rendered proteolytically inactive with the specific inhibitors d-Phe-Pro-ArgCH2Cl and hirudin, indicating that thrombin is mediating these effects via the proteolytic activation of PAR-1. These results suggest that thrombin might influence the deposition of connective tissue proteins during normal wound healing and the development of tissue fibrosis by stimulating fibroblast procollagen production. PMID:9639571

  11. Sunburn among active component service members, U.S. Armed Forces, 2002-2013.

    PubMed

    2014-07-01

    Sunburn is caused by acute overexposure to ultraviolet (UV) radiation directly from the sun or from artificial UV sources. Service members are at risk of excessive exposure to sunlight due to the nature of their military duties, which often involve working and training outdoors, and deployment to environments where UV radiation is more intense. From January 2002 through December 2013, a total of 19,172 incident cases of clinically significant sunburn were diagnosed among active component service members. Most of the cases (80.2%) were first degree sunburn. The incidence rates of sunburn diagnoses were higher among females, white non-Hispanics, younger age groups, individuals in the Marine Corps or Army, and among enlisted service members. Additionally, the rate among recruits was more than 3.5 times the rate for non-recruits. Sixty-one percent of all diagnosed cases occurred from May through July. Sunburn cases occurred in all areas of the U.S., particularly near major recruit and combat training locations. Service members are strongly advised to practice sun safety as a part of heat illness prevention, including properly using broad-spectrum sunscreen, finding or constructing shade during work and rest, wearing protective clothing and military combat eye protection items, and avoiding tanning booths and sun lamps. PMID:25080329

  12. Septicemia diagnosed during hospitalizations, active component service members, U.S. Armed Forces, 2000-2012.

    PubMed

    2013-08-01

    During the period 2000 through 2012, the records of 3,360 hospitalized active component service members contained a diagnosis of septicemia. Most of these cases were identified via diagnoses recorded in the first and second diagnostic positions and the numbers and rates of such cases increased dramatically during the period. Rates were higher among women than men and in the oldest and youngest age groups. The most frequent co-occurring diagnoses were pneumonia and infections of the skin and subcutaneous tissue. For the majority of cases of septicemia, no specific etiologic agent was indicated by ICD-9 codes in the record. The most commonly specified agents were Staphylococcus aureus, Escherichia coli, and Streptococcus pneumoniae. Most service members were returned to duty after discharge. The overall mortality associated with hospitalized septicemia cases was 4 percent, but was 5.1 percent for septicemia attributed to gram negative bacteria. Possible reasons why the mortality rate in service members was lower than the rates associated with septicemia in the general population are discussed. PMID:24011371

  13. 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

  14. Biomechanical forces exert anabolic effects on osteoblasts by activation of SMAD 1/5/8 through type 1 BMP receptor

    PubMed Central

    Rath, B.; Nam, J.; Deschner, J.; Schaumburger, J.; Tingart, M.; Grässel, S.; Grifka, J.; Agarwal, S.

    2016-01-01

    Osteoblasts are mechanosensitive cells, which respond to biomechanical stimuli to regulate the bone structure through anabolic and catabolic gene regulation. To examine the effects of mechanical forces on the osteogenic responses through the SMAD signaling in osteoblasts, the cells were cultured in well-characterized mechanoresponsive 3-D scaffolds and exposed to 10% dynamic compressive strain (Cmp) at 1 Hz. Subsequently, SMAD phosphorylation and osteogenic gene induction was examined. Osteoblasts cultured in 3-D scaffolds exhibited increased constitutive SMAD 1/5/8 phosphorylation, as compared to monolayers cultures. This SMAD 1/5/8 phosphorylation was further upregulated after 10, 30 and 60 min in response to Cmp, exhibiting a peak activation at 30 min. No significant changes in SMAD2 phosphorylation were observed, suggesting signals generated by Cmp may not activate the Transforming Growth Factor-β signaling cascade. Subsequently, biomechanical stimulation-induced SMAD 1/5/8 phosphorylation upregulated the expression of osteogenic genes such as Osteoprotegrin, Msx2 and Runx2. Dorsomorphin, a selective inhibitor of the bone morphogenetic protein (BMP) receptor type 1 (BMPR1), blocked Cmp-induced SMAD 1/5/8 phosphorylation, as well as Osteoprotegrin, Msx2 and Runx2 gene expression. Collectively, the present findings demonstrate that biomechanical stimulation of osteoblasts activates SMAD 1/5/8 in the BMP signaling pathway through BMPR1 and may enhance osteogenesis by upregulating SMAD-dependent osteogenic genes. PMID:21515935

  15. Response of Northern Hemisphere Mid- and High- Latitude Storm Activities to Arctic Sea Ice Forcing: A Modeling Investigation

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Basu, S.

    2015-12-01

    Arctic sea ice has exhibited a rapid reduction and large fluctuations during recent decades in conjunction with a warming climate. To identify sea ice impacts on extratropical storm tracks and associated surface climate, we employed the NCAR's Community Atmosphere Model to conduct a suite of sensitivity experiments, in which the model is solely forced with observed time-varying sea-ice concentration from 1979 to 2008. A storm identification and tracking algorithm was applied for analyzing variability of and changes in storm activities simulated by the model. The results show that reduced sea-ice cover enhances Arctic storm activity and increases warm moist air advection into the Arctic. As a consequence, Arctic surface air temperature (SAT) throughout the year and precipitation in spring, summer and fall seasons increase. By contrast, storm activity weakens and anticyclones strengthen over Eurasia. The strengthened anticyclones lead to a decrease in cloud cover, precipitation and SATs in both fall and winter seasons. These findings also suggest that Arctic sea ice not only impacts local, but also lower latitude weathers and climate.

  16. Update: Exertional hyponatremia, active component, U.S. Army, Navy, Air Force, and Marine Corps, 2000-2015.

    PubMed

    2016-03-01

    From 2000 through 2015, there were 1,542 incident diagnoses of exertional hyponatremia among active component members of the U.S. Army, Navy, Air Force, and Marine Corps. Annual incidence rates rose sharply from 2008 through 2010 but then decreased by more than 50% from 2010 through 2013. In 2015, the number of cases (n=116) increased by approximately 20% from the previous year. The recent increase in rates overall reflects increased rates in the Army and the Marine Corps. Relative to their respective counterparts, crude incidence rates of exertional hyponatremia for the entire 16-year surveillance period were higher among females, those in the youngest age group, Marines, and recruit trainees. Service members (particularly recruit trainees) and their supervisors must be vigilant for early signs of heat-related illnesses and must be knowledgeable of the dangers of excessive water consumption and the prescribed limits for water intake during prolonged physical activity (e.g., field training exercises, personal fitness training, recreational activities) in hot, humid weather. PMID:27030930

  17. Influence of Adhesion Force on icaA and cidA Gene Expression and Production of Matrix Components in Staphylococcus aureus Biofilms

    PubMed Central

    Harapanahalli, Akshay K.; Chen, Yun; Li, Jiuyi; Busscher, Henk J.

    2015-01-01

    The majority of human infections are caused by biofilms. The biofilm mode of growth enhances the pathogenicity of Staphylococcus spp. considerably, because once they adhere, staphylococci embed themselves in a protective, self-produced matrix of extracellular polymeric substances (EPSs). The aim of this study was to investigate the influence of forces of staphylococcal adhesion to different biomaterials on icaA (which regulates the production of EPS matrix components) and cidA (which is associated with cell lysis and extracellular DNA [eDNA] release) gene expression in Staphylococcus aureus biofilms. Experiments were performed with S. aureus ATCC 12600 and its isogenic mutant, S. aureus ATCC 12600 Δpbp4, deficient in peptidoglycan cross-linking. Deletion of pbp4 was associated with greater cell wall deformability, while it did not affect the planktonic growth rate, biofilm formation, cell surface hydrophobicity, or zeta potential of the strains. The adhesion forces of S. aureus ATCC 12600 were the strongest on polyethylene (4.9 ± 0.5 nN), intermediate on polymethylmethacrylate (3.1 ± 0.7 nN), and the weakest on stainless steel (1.3 ± 0.2 nN). The production of poly-N-acetylglucosamine, eDNA presence, and expression of icaA genes decreased with increasing adhesion forces. However, no relation between adhesion forces and cidA expression was observed. The adhesion forces of the isogenic mutant S. aureus ATCC 12600 Δpbp4 (deficient in peptidoglycan cross-linking) were much weaker than those of the parent strain and did not show any correlation with the production of poly-N-acetylglucosamine, eDNA presence, or expression of the icaA and cidA genes. This suggests that adhesion forces modulate the production of the matrix molecule poly-N-acetylglucosamine, eDNA presence, and icaA gene expression by inducing nanoscale cell wall deformation, with cross-linked peptidoglycan layers playing a pivotal role in this adhesion force sensing. PMID:25746995

  18. Influence of Adhesion Force on icaA and cidA Gene Expression and Production of Matrix Components in Staphylococcus aureus Biofilms.

    PubMed

    Harapanahalli, Akshay K; Chen, Yun; Li, Jiuyi; Busscher, Henk J; van der Mei, Henny C

    2015-05-15

    The majority of human infections are caused by biofilms. The biofilm mode of growth enhances the pathogenicity of Staphylococcus spp. considerably, because once they adhere, staphylococci embed themselves in a protective, self-produced matrix of extracellular polymeric substances (EPSs). The aim of this study was to investigate the influence of forces of staphylococcal adhesion to different biomaterials on icaA (which regulates the production of EPS matrix components) and cidA (which is associated with cell lysis and extracellular DNA [eDNA] release) gene expression in Staphylococcus aureus biofilms. Experiments were performed with S. aureus ATCC 12600 and its isogenic mutant, S. aureus ATCC 12600 Δpbp4, deficient in peptidoglycan cross-linking. Deletion of pbp4 was associated with greater cell wall deformability, while it did not affect the planktonic growth rate, biofilm formation, cell surface hydrophobicity, or zeta potential of the strains. The adhesion forces of S. aureus ATCC 12600 were the strongest on polyethylene (4.9 ± 0.5 nN), intermediate on polymethylmethacrylate (3.1 ± 0.7 nN), and the weakest on stainless steel (1.3 ± 0.2 nN). The production of poly-N-acetylglucosamine, eDNA presence, and expression of icaA genes decreased with increasing adhesion forces. However, no relation between adhesion forces and cidA expression was observed. The adhesion forces of the isogenic mutant S. aureus ATCC 12600 Δpbp4 (deficient in peptidoglycan cross-linking) were much weaker than those of the parent strain and did not show any correlation with the production of poly-N-acetylglucosamine, eDNA presence, or expression of the icaA and cidA genes. This suggests that adhesion forces modulate the production of the matrix molecule poly-N-acetylglucosamine, eDNA presence, and icaA gene expression by inducing nanoscale cell wall deformation, with cross-linked peptidoglycan layers playing a pivotal role in this adhesion force sensing. PMID:25746995

  19. Systemic complement activation, lung injury, and products of lipid peroxidation.

    PubMed Central

    Ward, P A; Till, G O; Hatherill, J R; Annesley, T M; Kunkel, R G

    1985-01-01

    Previously we have demonstrated that systemic activation of the complement system after intravenous injection of cobra venom factor (CVF) results in acute lung injury as reflected by increases in the vascular permeability of the lung as well as by morphologic evidence of damage to lung vascular endothelial cells. In using the vascular permeability of the lung as the reference, the current studies show a quantitative correlation between lung injury and the appearance in plasma of lipid peroxidation products (conjugated dienes) as well as increased concentrations of lactic dehydrogenase (LDH) and one of its isoenzymes (LDH-4). After injection of CVF, extracts of lungs also showed elevated levels of conjugated dienes, whereas no elevations were found in extracts of liver, kidney, and spleen. There was no evidence in CVF-injected rats of renal or hepatic injury as reflected by the lack of development of proteinuria and the failure to detect increased serum levels of liver-related enzymes. Other peroxidation products identified in plasma of CVF-injected rats involved hydroperoxides and fluorescent compounds with features of Schiff bases. Not surprisingly, malondialdehyde was not found to be a reliable plasma indicator of lipid peroxidation associated with oxygen radical-mediated lung vascular injury. In using a model of oxygen radical-independent lung injury induced by oleic acid, although large amounts of LDH and LDH-4 were found in the plasma, no increases in plasma levels of conjugated dienes were detected. In CVF-injected animals treated with interventions protective against lung injury (neutrophil depletion, catalase, hydroxyl radical scavengers, or iron chelators), there were striking reductions in the plasma levels of conjugated dienes, hydroperoxides, and fluorochromic products. Morphometric analysis of lung sections revealed that the protective interventions did not interfere with the accumulation of neutrophils in lung interstitial capillaries after systemic

  20. Muscle activation during maximal effort tasks: evidence of the selective forces that shaped the musculoskeletal system of humans

    PubMed Central

    Carrier, David R.; Schilling, Nadja; Anders, Christoph

    2015-01-01

    ABSTRACT The selective forces that played a role in the evolution of the musculoskeletal system of the genus Homo have long been debated and remain poorly understood. In this investigation, we introduce a new approach for testing alternative hypotheses. Our analysis is based on the premise that natural selection can be expected to have resulted in muscles that are large enough to achieve necessary levels of maximum performance in essential behaviors, but not larger. We used surface electromyography in male subjects to identify maximum activation levels in 13 muscles of the back and leg during eight behaviors that have been suggested to have been important to foraging, hunting and fighting performance in early humans. We asked two questions: (1) what behaviors produce maximum activation in each of the investigated muscles and (2) are there specific behaviors that elicit maximum recruitment from all or most of the muscles? We found that in eight of the 13 muscles, the highest activity occurred during maximal effort vertical jumping (i.e. whole-body acceleration). Punching produced the highest median activity in the other five muscles. Together, jumping and punching accounted for 73% of the incidences of maximum activity among all of the muscles and from all of the subjects. Thus, the size of the muscles of the back and leg appear to be more related to the demands of explosive behaviors rather than those of high speed sprinting or sustained endurance running. These results are consistent with the hypothesis that selection on aggressive behavior played an important role in the evolution of the genus Homo. PMID:26538637

  1. Muscle activation during maximal effort tasks: evidence of the selective forces that shaped the musculoskeletal system of humans.

    PubMed

    Carrier, David R; Schilling, Nadja; Anders, Christoph

    2015-01-01

    The selective forces that played a role in the evolution of the musculoskeletal system of the genus Homo have long been debated and remain poorly understood. In this investigation, we introduce a new approach for testing alternative hypotheses. Our analysis is based on the premise that natural selection can be expected to have resulted in muscles that are large enough to achieve necessary levels of maximum performance in essential behaviors, but not larger. We used surface electromyography in male subjects to identify maximum activation levels in 13 muscles of the back and leg during eight behaviors that have been suggested to have been important to foraging, hunting and fighting performance in early humans. We asked two questions: (1) what behaviors produce maximum activation in each of the investigated muscles and (2) are there specific behaviors that elicit maximum recruitment from all or most of the muscles? We found that in eight of the 13 muscles, the highest activity occurred during maximal effort vertical jumping (i.e. whole-body acceleration). Punching produced the highest median activity in the other five muscles. Together, jumping and punching accounted for 73% of the incidences of maximum activity among all of the muscles and from all of the subjects. Thus, the size of the muscles of the back and leg appear to be more related to the demands of explosive behaviors rather than those of high speed sprinting or sustained endurance running. These results are consistent with the hypothesis that selection on aggressive behavior played an important role in the evolution of the genus Homo. PMID:26538637

  2. Active Control of the Forced and Transient Response of a Finite Beam. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Post, John Theodore

    1989-01-01

    When studying structural vibrations resulting from a concentrated source, many structures may be modelled as a finite beam excited by a point source. The theoretical limit on cancelling the resulting beam vibrations by utilizing another point source as an active controller is explored. Three different types of excitation are considered, harmonic, random, and transient. In each case, a cost function is defined and minimized for numerous parameter variations. For the case of harmonic excitation, the cost function is obtained by integrating the mean squared displacement over a region of the beam in which control is desired. A controller is then found to minimize this cost function in the control interval. The control interval and controller location are continuously varied for several frequencies of excitation. The results show that control over the entire beam length is possible only when the excitation frequency is near a resonant frequency of the beam, but 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, the cost function is realized by integrating the expected value of the displacement squared over the interval of the beam in which control is desired. This 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. A cost function representative of the beam vibration is obtained by integrating the transient displacement squared over a region of the beam and over all time. The form of the controller is chosen a priori as either one or two delayed pulses. Delays

  3. Evidence of a double peak in muscle activation to enhance strike speed and force: an example with elite mixed martial arts fighters.

    PubMed

    McGill, Stuart M; Chaimberg, Jon D; Frost, David M; Fenwick, Chad M J

    2010-02-01

    The main issue addressed here is the paradox of muscle contraction to optimize speed and strike force. When muscle contracts, it increases in both force and stiffness. Force creates faster movement, but the corresponding stiffness slows th