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Sample records for control underwater locomotor

  1. Neuronal control of locomotor handedness in Drosophila.

    PubMed

    Buchanan, Sean M; Kain, Jamey S; de Bivort, Benjamin L

    2015-05-26

    Genetically identical individuals display variability in their physiology, morphology, and behaviors, even when reared in essentially identical environments, but there is little mechanistic understanding of the basis of such variation. Here, we investigated whether Drosophila melanogaster displays individual-to-individual variation in locomotor behaviors. We developed a new high-throughout platform capable of measuring the exploratory behavior of hundreds of individual flies simultaneously. With this approach, we find that, during exploratory walking, individual flies exhibit significant bias in their left vs. right locomotor choices, with some flies being strongly left biased or right biased. This idiosyncrasy was present in all genotypes examined, including wild-derived populations and inbred isogenic laboratory strains. The biases of individual flies persist for their lifetime and are nonheritable: i.e., mating two left-biased individuals does not yield left-biased progeny. This locomotor handedness is uncorrelated with other asymmetries, such as the handedness of gut twisting, leg-length asymmetry, and wing-folding preference. Using transgenics and mutants, we find that the magnitude of locomotor handedness is under the control of columnar neurons within the central complex, a brain region implicated in motor planning and execution. When these neurons are silenced, exploratory laterality increases, with more extreme leftiness and rightiness. This observation intriguingly implies that the brain may be able to dynamically regulate behavioral individuality.

  2. Neuronal control of locomotor handedness in Drosophila

    PubMed Central

    Buchanan, Sean M.; Kain, Jamey S.; de Bivort, Benjamin L.

    2015-01-01

    Genetically identical individuals display variability in their physiology, morphology, and behaviors, even when reared in essentially identical environments, but there is little mechanistic understanding of the basis of such variation. Here, we investigated whether Drosophila melanogaster displays individual-to-individual variation in locomotor behaviors. We developed a new high-throughout platform capable of measuring the exploratory behavior of hundreds of individual flies simultaneously. With this approach, we find that, during exploratory walking, individual flies exhibit significant bias in their left vs. right locomotor choices, with some flies being strongly left biased or right biased. This idiosyncrasy was present in all genotypes examined, including wild-derived populations and inbred isogenic laboratory strains. The biases of individual flies persist for their lifetime and are nonheritable: i.e., mating two left-biased individuals does not yield left-biased progeny. This locomotor handedness is uncorrelated with other asymmetries, such as the handedness of gut twisting, leg-length asymmetry, and wing-folding preference. Using transgenics and mutants, we find that the magnitude of locomotor handedness is under the control of columnar neurons within the central complex, a brain region implicated in motor planning and execution. When these neurons are silenced, exploratory laterality increases, with more extreme leftiness and rightiness. This observation intriguingly implies that the brain may be able to dynamically regulate behavioral individuality. PMID:25953337

  3. Underwater Glider Dynamics and Control

    DTIC Science & Technology

    2002-09-30

    colleagues for underactuated systems (see, for example, Bloch, Leonard and Marsden [2001]). The method of controlled Lagrangians is a control...suited to underactuated systems , i.e., systems like underwater gliders that have fewer control inputs than system degrees of freedom. We will also... underactuated and constrained systems . In earlier work we have developed coordinated control strategies for fully actuated point mass vehicle models

  4. UNDERWATER COATINGS FOR CONTAMINATION CONTROL

    SciTech Connect

    Julia L. Tripp; Kip Archibald; Ann Marie Phillips; Joseph Campbell

    2004-02-01

    The Idaho National Laboratory (INL) deactivated several aging nuclear fuel storage basins. Planners for this effort were greatly concerned that radioactive contamination present on the basin walls could become airborne as the sides of the basins became exposed during deactivation and allowed to dry after water removal. One way to control this airborne contamination was to fix the contamination in place while the pool walls were still submerged. There are many underwater coatings available on the market for marine, naval and other applications. A series of tests were run to determine whether the candidate underwater fixatives were easily applied and adhered well to the substrates (pool wall materials) found in INL fuel pools. Lab-scale experiments were conducted by applying fourteen different commercial underwater coatings to four substrate materials representative of the storage basin construction materials, and evaluating their performance. The coupons included bare concrete, epoxy painted concrete, epoxy painted carbon steel, and stainless steel. The evaluation criteria included ease of application, adherence to the four surfaces of interest, no change on water clarity or chemistry, non-hazardous in final applied form and be proven in underwater applications. A proprietary two-part, underwater epoxy owned by S. G. Pinney and Associates was selected from the underwater coatings tested for application to all four pools. Divers scrubbed loose contamination off the basin walls and floors using a ship hull scrubber and vacuumed up the sludge. The divers then applied the coating using a special powered roller with two separate heated hoses that allowed the epoxy to mix at the roller surface was used to eliminate pot time concerns. The walls were successfully coated and water was removed from the pools with no detectable airborne contamination releases.

  5. Underwater Glider Dynamics and Control

    DTIC Science & Technology

    2003-09-30

    Lyapunov function design for proving stability of mechanical systems that we have recently developed with colleagues for underactuated systems (see...that modifies system energy so that the motion of interest is stable. The method is particularly well suited to underactuated systems , i.e., systems ...like underwater gliders that have fewer control inputs than system degrees of freedom. To make this method relevant to mechanical systems with

  6. Underwater Coatings for Contamination Control

    SciTech Connect

    Julia L. Tripp; Kip Archibald; Ann-Marie Phillips; Joseph Campbell

    2004-02-01

    The Idaho National Engineering and Environmental Laboratory (INEEL) is deactivating several fuel storage basins. Airborne contamination is a concern when the sides of the basins are exposed and allowed to dry during water removal. One way of controlling this airborne contamination is to fix the contamination in place while the pool walls are still submerged. There are many underwater coatings available on the market that are used in marine, naval and other applications. A series of tests were run to determine whether the candidate underwater fixatives are easily applied and adhere well to the substrates (pool wall materials) found in INEEL fuel pools. The four pools considered included 1) Test Area North (TAN-607) with epoxy painted concrete walls; 2) Idaho Nuclear Technology and Engineering Center (INTEC) (CPP-603) with bare concrete walls; 3) Materials Test Reactor (MTR) Canal with stainless steel lined concrete walls; and 4) Power Burst Facility (PBF-620) with stainless steel lined concrete walls on the bottom and epoxy painted carbon steel lined walls on the upper portions. Therefore, the four materials chosen for testing included bare concrete, epoxy painted concrete, epoxy painted carbon steel, and stainless steel. The typical water temperature of the pools varies from 55oF to 80oF dependent on the pool and the season. These tests were done at room temperature. The following criteria were used during this evaluation. The underwater coating must: · Be easy to apply · Adhere well to the four surfaces of interest · Not change or have a negative impact on water chemistry or clarity · Not be hazardous in final applied form · Be proven in other underwater applications. In addition, it is desirable for the coating to have a high pigment or high cross-link density to prevent radiation from penetrating. This paper will detail the testing completed and the test results. A proprietary two-part, underwater epoxy owned by S. G. Pinney and Associates was selected to

  7. Effects of space flight on locomotor control

    NASA Technical Reports Server (NTRS)

    Bloomberg, Jacob J.; Layne, Charles S.; McDonald, P. Vernon; Peters, Brian T.; Huebner, William P.; Reschke, Millard F.; Berthoz, Alain; Glasauer, Stefan; Newman, Dava; Jackson, D. Keoki

    1999-01-01

    In the microgravity environment of spaceflight, the relationship between sensory input and motor output is altered. During prolonged missions, neural adaptive processes come into play to recalibrate central nervous system function, thereby permitting new motor control strategies to emerge in the novel sensory environment of microgravity. However, the adaptive state achieved during spaceflight is inappropriate for a unit gravity environment and leads to motor control alterations upon return to Earth that include disturbances in locomotion. Indeed, gait and postural instabilities following the return to Earth have been reported in both U.S. astronauts and Russian cosmonauts even after short duration (5- to 10-day) flights. After spaceflight, astronauts may: (1) experience the sensation of turning while attempting to walk a straight path, (2) encounter sudden loss of postural stability, especially when rounding corners, (3) perceive exaggerated pitch and rolling head movements during walking, (4) experience sudden loss of orientation in unstructured visual environments, or (5) experience significant oscillopsia during locomotion.

  8. Locomotor adaptation to a soleus EMG-controlled antagonistic exoskeleton.

    PubMed

    Gordon, Keith E; Kinnaird, Catherine R; Ferris, Daniel P

    2013-04-01

    Locomotor adaptation in humans is not well understood. To provide insight into the neural reorganization that occurs following a significant disruption to one's learned neuromuscular map relating a given motor command to its resulting muscular action, we tied the mechanical action of a robotic exoskeleton to the electromyography (EMG) profile of the soleus muscle during walking. The powered exoskeleton produced an ankle dorsiflexion torque proportional to soleus muscle recruitment thus limiting the soleus' plantar flexion torque capability. We hypothesized that neurologically intact subjects would alter muscle activation patterns in response to the antagonistic exoskeleton by decreasing soleus recruitment. Subjects practiced walking with the exoskeleton for two 30-min sessions. The initial response to the perturbation was to "fight" the resistive exoskeleton by increasing soleus activation. By the end of training, subjects had significantly reduced soleus recruitment resulting in a gait pattern with almost no ankle push-off. In addition, there was a trend for subjects to reduce gastrocnemius recruitment in proportion to the soleus even though only the soleus EMG was used to control the exoskeleton. The results from this study demonstrate the ability of the nervous system to recalibrate locomotor output in response to substantial changes in the mechanical output of the soleus muscle and associated sensory feedback. This study provides further evidence that the human locomotor system of intact individuals is highly flexible and able to adapt to achieve effective locomotion in response to a broad range of neuromuscular perturbations.

  9. Underwater space suit pressure control regulator

    NASA Technical Reports Server (NTRS)

    Aldrich, B. R.; Cooper, C. R.; Rasquin, J. R. (Inventor)

    1973-01-01

    A device is reported for regulating the pneumatic pressure in a ventilated space suit relative to the pressure imposed on the suit when being worn by a person underwater to simulate space environment for testing and experimentation. A box unit located on the chest area of the suit comprises connections for suit air supply and return lines and carries a regulator valve that stabilizes the air pressure differential between the inside and outside of the suit. The valve and suit pressure is controlled by the suit occupant and the valve includes a mechanism for quickly dumping the suit pressure in case of emergency. Pressure monitoring and relief devices are also included in the box unit.

  10. Measurements of optical underwater turbulence under controlled conditions

    NASA Astrophysics Data System (ADS)

    Kanaev, A. V.; Gladysz, S.; Almeida de Sá Barros, R.; Matt, S.; Nootz, G. A.; Josset, D. B.; Hou, W.

    2016-05-01

    Laser beam propagation underwater is becoming an important research topic because of high demand for its potential applications. Namely, ability to image underwater at long distances is highly desired for scientific and military purposes, including submarine awareness, diver visibility, and mine detection. Optical communication in the ocean can provide covert data transmission with much higher rates than that available with acoustic techniques, and it is now desired for certain military and scientific applications that involve sending large quantities of data. Unfortunately underwater environment presents serious challenges for propagation of laser beams. Even in clean ocean water, the extinction due to absorption and scattering theoretically limit the useful range to few attenuation lengths. However, extending the laser light propagation range to the theoretical limit leads to significant beam distortions due to optical underwater turbulence. Experiments show that the magnitude of the distortions that are caused by water temperature and salinity fluctuations can significantly exceed the magnitude of the beam distortions due to atmospheric turbulence even for relatively short propagation distances. We are presenting direct measurements of optical underwater turbulence in controlled conditions of laboratory water tank using two separate techniques involving wavefront sensor and LED array. These independent approaches will enable development of underwater turbulence power spectrum model based directly on the spatial domain measurements and will lead to accurate predictions of underwater beam propagation.

  11. Remote Control of Respiratory Neural Network by Spinal Locomotor Generators

    PubMed Central

    Le Gal, Jean-Patrick; Juvin, Laurent; Cardoit, Laura; Thoby-Brisson, Muriel; Morin, Didier

    2014-01-01

    During exercise and locomotion, breathing rate rapidly increases to meet the suddenly enhanced oxygen demand. The extent to which direct central interactions between the spinal networks controlling locomotion and the brainstem networks controlling breathing are involved in this rhythm modulation remains unknown. Here, we show that in isolated neonatal rat brainstem-spinal cord preparations, the increase in respiratory rate observed during fictive locomotion is associated with an increase in the excitability of pre-inspiratory neurons of the parafacial respiratory group (pFRG/Pre-I). In addition, this locomotion-induced respiratory rhythm modulation is prevented both by bilateral lesion of the pFRG region and by blockade of neurokinin 1 receptors in the brainstem. Thus, our results assign pFRG/Pre-I neurons a new role as elements of a previously undescribed pathway involved in the functional interaction between respiratory and locomotor networks, an interaction that also involves a substance P-dependent modulating mechanism requiring the activation of neurokinin 1 receptors. This neurogenic mechanism may take an active part in the increased respiratory rhythmicity produced at the onset and during episodes of locomotion in mammals. PMID:24586951

  12. Active Gaze, Visual Look-Ahead, and Locomotor Control

    ERIC Educational Resources Information Center

    Wilkie, Richard M.; Wann, John P.; Allison, Robert S.

    2008-01-01

    The authors examined observers steering through a series of obstacles to determine the role of active gaze in shaping locomotor trajectories. Participants sat on a bicycle trainer integrated with a large field-of-view simulator and steered through a series of slalom gates. Steering behavior was determined by examining the passing distance through…

  13. Application of Sampling Based Model Predictive Control to an Autonomous Underwater Vehicle

    DTIC Science & Technology

    2010-07-01

    55 Application of Sampling Based Model Predictive Control to an Autonomous Underwater Vehicle Unmanned Underwater Vehicles (UUVs) can be utilized...the vehicle can feasibly traverse. As a result, Sampling- Based Model Predictive Control (SBMPC) is proposed to simultaneously generate control...inputs and system trajectories for an autonomous underwater vehicle (AUV). The algorithm combines the benefits of sampling- based motion planning with

  14. Nested task constraints shape continuous perception-action coupling control during human locomotor pointing.

    PubMed

    Renshaw, Ian; Davids, Keith

    2004-10-14

    Behavioural studies of human locomotor pointing have been dominated by specific task constraints of generating maximal approach velocity towards spatial targets. To examine locomotor pointing under different nested task constraints, at sub-maximal approach velocities and with concomitant differences in speed-accuracy trade offs, run-ups of professional cricket bowlers (n = 6) were analysed. Inter- and intra-trial analyses of step length adjustments revealed how differences between current and required locomotor pointing behaviour constrained visual adaptations of gait. Results supported a continuous perception-action coupling control mechanism, although no relationship was observed between step number in sequence and total amount of adjustment made, implying that visual adaptations did not continue to the end of a run-up once initiated. Rather, bowlers made step adjustments throughout the run-up, with strong associations for amount of adjustment made and amount needed. Significant variations were observed in inter-individual strategies for making most adjustments at different points of the run-up. A key premise of prospective control models of locomotor pointing was found to be robust, since regulation of cricketer's gait was continuous and based on perception of current and required behaviour. Findings extend understanding of the nature and range of nested task constraints under which perception-action coupling controls locomotor pointing performance.

  15. Cell-Type-Specific Control of Brainstem Locomotor Circuits by Basal Ganglia

    PubMed Central

    Roseberry, Thomas K.; Lee, A. Moses; Lalive, Arnaud L.; Wilbrecht, Linda; Bonci, Antonello; Kreitzer, Anatol C.

    2015-01-01

    Summary The basal ganglia (BG) are critical for adaptive motor control, but the circuit principles underlying their pathway-specific modulation of target regions are not well understood. Here, we dissect the mechanisms underlying BG direct- and indirect-pathway-mediated control of the mesencephalic locomotor region (MLR), a brainstem target of the BG that is critical for locomotion. We optogenetically dissect the locomotor function of the three neurochemically-distinct cell types within the MLR: glutamatergic, GABAergic, and cholinergic neurons. We find that the glutamatergic subpopulation encodes locomotor state and speed, is necessary and sufficient for locomotion, and is selectively innervated by BG. We further show activation and suppression, respectively, of MLR glutamatergic neurons by direct and indirect pathways, which is required for bidirectional control of locomotion by BG circuits. These findings provide a fundamental understanding of how the BG can initiate or suppress a motor program through cell-type-specific regulation of neurons linked to specific actions. PMID:26824660

  16. Tracking Control for Autonomous Underwater Vehicles

    DTIC Science & Technology

    2002-12-01

    Unclassified 20. LIMITATION OF ABSTRACT UL NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89) Prescribed by ANSI Std. 239-18 ii...could be developed and tuned to better handle this tracking control problem. This example will merely set a standard for which to compare later control...Change to disrcete [Ecd,Fcd]=c2d(Ec,Fc,dt); [Asd,Bsd]=c2d(As,Bs,dt); [ Asdm ,Bsdm]=c2d(Asm,Bsm,dt); % Aries response with error space

  17. Modular control of varied locomotor tasks in children with incomplete spinal cord injuries.

    PubMed

    Fox, Emily J; Tester, Nicole J; Kautz, Steven A; Howland, Dena R; Clark, David J; Garvan, Cyndi; Behrman, Andrea L

    2013-09-01

    A module is a functional unit of the nervous system that specifies functionally relevant patterns of muscle activation. In adults, four to five modules account for muscle activation during walking. Neurological injury alters modular control and is associated with walking impairments. The effect of neurological injury on modular control in children is unknown and may differ from adults due to their immature and developing nervous systems. We examined modular control of locomotor tasks in children with incomplete spinal cord injuries (ISCIs) and control children. Five controls (8.6 ± 2.7 yr of age) and five children with ISCIs (8.6 ± 3.7 yr of age performed treadmill walking, overground walking, pedaling, supine lower extremity flexion/extension, stair climbing, and crawling. Electromyograms (EMGs) were recorded in bilateral leg muscles. Nonnegative matrix factorization was applied, and the minimum number of modules required to achieve 90% of the "variance accounted for" (VAF) was calculated. On average, 3.5 modules explained muscle activation in the controls, whereas 2.4 modules were required in the children with ISCIs. To determine if control is similar across tasks, the module weightings identified from treadmill walking were used to reconstruct the EMGs from each of the other tasks. This resulted in VAF values exceeding 86% for each child and each locomotor task. Our results suggest that 1) modularity is constrained in children with ISCIs and 2) for each child, similar neural control mechanisms are used across locomotor tasks. These findings suggest that interventions that activate the neuromuscular system to enhance walking also may influence the control of other locomotor tasks.

  18. Monitoring and Controlling an Underwater Robotic Arm

    NASA Technical Reports Server (NTRS)

    Haas, John; Todd, Brian Keith; Woodcock, Larry; Robinson, Fred M.

    2009-01-01

    The SSRMS Module 1 software is part of a system for monitoring an adaptive, closed-loop control of the motions of a robotic arm in NASA s Neutral Buoyancy Laboratory, where buoyancy in a pool of water is used to simulate the weightlessness of outer space. This software is so named because the robot arm is a replica of the Space Shuttle Remote Manipulator System (SSRMS). This software is distributed, running on remote joint processors (RJPs), each of which is mounted in a hydraulic actuator comprising the joint of the robotic arm and communicating with a poolside processor denoted the Direct Control Rack (DCR). Each RJP executes the feedback joint-motion control algorithm for its joint and communicates with the DCR. The DCR receives joint-angular-velocity commands either locally from an operator or remotely from computers that simulate the flight like SSRMS and perform coordinated motion calculations based on hand-controller inputs. The received commands are checked for validity before they are transmitted to the RJPs. The DCR software generates a display of the statuses of the RJPs for the DCR operator and can shut down the hydraulic pump when excessive joint-angle error or failure of a RJP is detected.

  19. Human spinal locomotor control is based on flexibly organized burst generators.

    PubMed

    Danner, Simon M; Hofstoetter, Ursula S; Freundl, Brigitta; Binder, Heinrich; Mayr, Winfried; Rattay, Frank; Minassian, Karen

    2015-03-01

    Constant drive provided to the human lumbar spinal cord by epidural electrical stimulation can cause local neural circuits to generate rhythmic motor outputs to lower limb muscles in people paralysed by spinal cord injury. Epidural spinal cord stimulation thus allows the study of spinal rhythm and pattern generating circuits without their configuration by volitional motor tasks or task-specific peripheral feedback. To reveal spinal locomotor control principles, we studied the repertoire of rhythmic patterns that can be generated by the functionally isolated human lumbar spinal cord, detected as electromyographic activity from the legs, and investigated basic temporal components shared across these patterns. Ten subjects with chronic, motor-complete spinal cord injury were studied. Surface electromyographic responses to lumbar spinal cord stimulation were collected from quadriceps, hamstrings, tibialis anterior, and triceps surae in the supine position. From these data, 10-s segments of rhythmic activity present in the four muscle groups of one limb were extracted. Such samples were found in seven subjects. Physiologically adequate cycle durations and relative extension- and flexion-phase durations similar to those needed for locomotion were generated. The multi-muscle activation patterns exhibited a variety of coactivation, mixed-synergy and locomotor-like configurations. Statistical decomposition of the electromyographic data across subjects, muscles and samples of rhythmic patterns identified three common temporal components, i.e. basic or shared activation patterns. Two of these basic patterns controlled muscles to contract either synchronously or alternatingly during extension- and flexion-like phases. The third basic pattern contributed to the observed muscle activities independently from these extensor- and flexor-related basic patterns. Each bifunctional muscle group was able to express both extensor- and flexor-patterns, with variable ratios across the

  20. Distinct sets of locomotor modules control the speed and modes of human locomotion

    PubMed Central

    Yokoyama, Hikaru; Ogawa, Tetsuya; Kawashima, Noritaka; Shinya, Masahiro; Nakazawa, Kimitaka

    2016-01-01

    Although recent vertebrate studies have revealed that different spinal networks are recruited in locomotor mode- and speed-dependent manners, it is unknown whether humans share similar neural mechanisms. Here, we tested whether speed- and mode-dependence in the recruitment of human locomotor networks exists or not by statistically extracting locomotor networks. From electromyographic activity during walking and running over a wide speed range, locomotor modules generating basic patterns of muscle activities were extracted using non-negative matrix factorization. The results showed that the number of modules changed depending on the modes and speeds. Different combinations of modules were extracted during walking and running, and at different speeds even during the same locomotor mode. These results strongly suggest that, in humans, different spinal locomotor networks are recruited while walking and running, and even in the same locomotor mode different networks are probably recruited at different speeds. PMID:27805015

  1. Locomotor adaptation to a powered ankle-foot orthosis depends on control method

    PubMed Central

    Cain, Stephen M; Gordon, Keith E; Ferris, Daniel P

    2007-01-01

    Background We studied human locomotor adaptation to powered ankle-foot orthoses with the intent of identifying differences between two different orthosis control methods. The first orthosis control method used a footswitch to provide bang-bang control (a kinematic control) and the second orthosis control method used a proportional myoelectric signal from the soleus (a physiological control). Both controllers activated an artificial pneumatic muscle providing plantar flexion torque. Methods Subjects walked on a treadmill for two thirty-minute sessions spaced three days apart under either footswitch control (n = 6) or myoelectric control (n = 6). We recorded lower limb electromyography (EMG), joint kinematics, and orthosis kinetics. We compared stance phase EMG amplitudes, correlation of joint angle patterns, and mechanical work performed by the powered orthosis between the two controllers over time. Results During steady state at the end of the second session, subjects using proportional myoelectric control had much lower soleus and gastrocnemius activation than the subjects using footswitch control. The substantial decrease in triceps surae recruitment allowed the proportional myoelectric control subjects to walk with ankle kinematics close to normal and reduce negative work performed by the orthosis. The footswitch control subjects walked with substantially perturbed ankle kinematics and performed more negative work with the orthosis. Conclusion These results provide evidence that the choice of orthosis control method can greatly alter how humans adapt to powered orthosis assistance during walking. Specifically, proportional myoelectric control results in larger reductions in muscle activation and gait kinematics more similar to normal compared to footswitch control. PMID:18154649

  2. Locomotor Adaptation Improves Balance Control, Multitasking Ability and Reduces the Metabolic Cost of Postural Instability

    NASA Technical Reports Server (NTRS)

    Bloomberg, J. J.; Peters, B. T.; Mulavara, A. P.; Brady, R. A.; Batson, C. D.; Miller, C. A.; Ploutz-Snyder, R. J.; Guined, J. R.; Buxton, R. E.; Cohen, H. S.

    2011-01-01

    During exploration-class missions, sensorimotor disturbances may lead to disruption in the ability to ambulate and perform functional tasks during the initial introduction to a novel gravitational environment following a landing on a planetary surface. The overall goal of our current project is to develop a sensorimotor adaptability training program to facilitate rapid adaptation to these environments. We have developed a unique training system comprised of a treadmill placed on a motion-base facing a virtual visual scene. It provides an unstable walking surface combined with incongruent visual flow designed to enhance sensorimotor adaptability. Greater metabolic cost incurred during balance instability means more physical work is required during adaptation to new environments possibly affecting crewmembers? ability to perform mission critical tasks during early surface operations on planetary expeditions. The goal of this study was to characterize adaptation to a discordant sensory challenge across a number of performance modalities including locomotor stability, multi-tasking ability and metabolic cost. METHODS: Subjects (n=15) walked (4.0 km/h) on a treadmill for an 8 -minute baseline walking period followed by 20-minutes of walking (4.0 km/h) with support surface motion (0.3 Hz, sinusoidal lateral motion, peak amplitude 25.4 cm) provided by the treadmill/motion-base system. Stride frequency and auditory reaction time were collected as measures of locomotor stability and multi-tasking ability, respectively. Metabolic data (VO2) were collected via a portable metabolic gas analysis system. RESULTS: At the onset of lateral support surface motion, subj ects walking on our treadmill showed an increase in stride frequency and auditory reaction time indicating initial balance and multi-tasking disturbances. During the 20-minute adaptation period, balance control and multi-tasking performance improved. Similarly, throughout the 20-minute adaptation period, VO2 gradually

  3. Synthesis of a PID-controller of a trim robust control system of an autonomous underwater vehicle

    NASA Astrophysics Data System (ADS)

    Khozhaev, I. V.; Gayvoronskiy, S. A.

    2016-04-01

    Autonomous underwater vehicles are often used for performing scientific, emergency or other types of missions under harsh conditions and environments, which can have non-stable, variable parameters. So, the problem of developing autonomous underwater vehicle motion control systems, capable of operating properly in random environments, is highly relevant. The paper is dedicated to the synthesis of a PID-controller of a trim robust control system, capable of keeping an underwater vehicle stable during a translation at different angles of attack. In order to synthesize the PID-controller, two problems were solved: a new method of synthesizing a robust controller was developed and a mathematical model of an underwater vehicle motion process was derived. The newly developed mathematical model structure is simpler than others due to acceptance of some of the system parameters as interval ones. The synthesis method is based on a system poles allocation approach and allows providing the necessary transient process quality in a considered system.

  4. Diverse neuronal lineages make stereotyped contributions to the Drosophila locomotor control center, the central complex

    PubMed Central

    He, Yisheng; Ding, Peng; Kao, Jui-Chun; Lee, Tzumin

    2013-01-01

    Summary The Drosophila central brain develops from a fixed number of neuroblasts. Each neuroblast makes a clone of neurons that exhibit common trajectories. Here we identified 15 distinct clones that carry larval-born neurons innervating the Drosophila central complex (CX), which consists of four midline structures including the protocerebral bridge (PB), fan-shape body (FB), ellipsoid body (EB), and noduli (NO). Clonal analysis revealed that the small-field CX neurons, which establish intricate projections across different CX substructures, exist in four isomorphic groups that respectively derive from four complex posterior asense-negative lineages. About the region-characteristic large-field CX neurons, we found that two lineages make PB neurons, ten lineages produce FB neurons, three lineages generate EB neurons, and two lineages yield NO neurons. The diverse FB developmental origins reflect the discrete input pathways for different FB subcompartments. Clonal analysis enlightens both development and anatomy of the insect locomotor control center. PMID:23696496

  5. Underwater characterization of control rods for waste disposal using SMOPY

    SciTech Connect

    Gallozzi-Ulmann, A.; Couturier, P.; Amgarou, K.; Rothan, D.; Menaa, N.; Chard, P.

    2015-07-01

    Storage of spent fuel assemblies in cooling ponds requires careful control of the geometry and proximity of adjacent assemblies. Measurement of the fuel burnup makes it possible to optimise the storage arrangement of assemblies taking into account the effect of the burnup on the criticality safety margins ('burnup credit'). Canberra has developed a measurement system for underwater measurement of spent fuel assemblies. This system, known as 'SMOPY', performs burnup measurements based on gamma spectroscopy (collimated CZT detector) and neutron counting (fission chamber). The SMOPY system offers a robust and waterproof detection system as well as the needed capability of performing radiometric measurements in the harsh high dose - rate environments of the cooling ponds. The gamma spectroscopy functionality allows powerful characterization measurements to be performed, in addition to burnup measurement. Canberra has recently performed waste characterisation measurements at a Nuclear Power Plant. Waste activity assessment is important to control costs and risks of shipment and storage, to ensure that the activity level remains in the range allowed by the facility, and to declare activity data to authorities. This paper describes the methodology used for the SMOPY measurements and some preliminary results of a radiological characterisation of AIC control rods. After describing the features and normal operation of the SMOPY system, we describe the approach used for establishing an optimum control rod geometric scanning approach (optimum count time and speed) and the method of the gamma spectrometry measurements as well as neutron check measurements used to verify the absence of neutron sources in the waste. We discuss the results obtained including {sup 60}Co, {sup 110m}Ag and {sup 108m}Ag activity profiles (along the length of the control rods) and neutron results including Total Measurement Uncertainty evaluations. Full self-consistency checks were performed and these

  6. The Interplay Between Strategic And Adaptive Control Mechanisms In Plastic Recalibration Of Locomotor Function

    NASA Technical Reports Server (NTRS)

    Richards, J. T.; Mulavara, A. P.; Bloomberg, J. J.

    2006-01-01

    We have previously shown that viewing simulated rotary self-motion during treadmill locomotion causes immediate strategic modifications (Richards et al. 2004) as well as an after effect reflecting adaptive modification of the control of position and trajectory during over-ground locomotion (Mulavara et al. 2005). The process of sensorimotor adaptation is comprised of both strategic and adaptive control mechanisms. Strategic control involves cognitive, on-line corrections to limb movements once one is aware of a sensory discordance. Over an extended period of exposure to the sensory discordance, new strategic sensorimotor coordination patterns are reinforced until they become more automatic, and therefore adaptive, in nature. The objective of this study was to investigate how strategic changes in trunk control during exposure to simulated rotary self-motion during treadmill walking influences adaptive modification of locomotor heading direction during over-ground stepping. Subjects (n = 10) walked on a motorized linear treadmill while viewing a wide field-of-view virtual scene for 24 minutes. The scene was static for the first 4 minutes and then, for the last 20 minutes, depicted constant rate self-motion equivalent to walking in a counter-clockwise, circular path around the perimeter of a room. Subjects performed five stepping trials both before and after the exposure period to assess after effects. Results from our previous study showed a significant change in heading direction (HD) during post-exposure step tests that was opposite the direction in which the scene rotated during the adaptation period. For the present study, we quantified strategic modifications in trunk movement control during scene exposure using normalized root mean square (R(sub p)) variation of the subject's 3D trunk positions and normalized sum of standard deviations (R(sub o)) variation of 3D trunk orientations during scene rotation relative to that during static scene presentation

  7. Design and implementation of control system for range-gated underwater laser imaging

    NASA Astrophysics Data System (ADS)

    Ge, Wei-Long; Zhang, Xiao-Hui; Han, Hong-Wei; Hua, Liang-Hong

    2011-11-01

    There is currently considerable in developing underwater target detection, the underwater imaging system can be divided into active imaging system and passive system. The main feature of the active imaging system is that they use light sources to illuminate the targets and collect the reflection from targets. The advantages of active imaging system over passive imaging systems are high contrast and without the affection of environment sources. In this article, a range-gated underwater laser imaging system is built, which consists of laser illumination system, photoelectric imaging system and control system. The laser illumination system includes a light-pumped solid state doubled ND-YAG laser(532nm) which laser power and frequency can be adjusted and an optics expanding system of variable ratio. The photoelectric imaging system includes a gated Intensified CCD(ICCD) cameras which ICCD scheduling, gate width, delay time and gain can be adjusted and a optics received system of variable ratio. In order to acquire effectual target image using range-gated underwater laser imaging system, appropriate control parameters that include laser power and frequency, ICCD scheduling, gate width, delay time and gain, optics expanding system ratio and optics received system ratio must be given accurately. A control system which used C8051F320 and C8051F040 (MCU) as the core is designed, the control system can effectively control seven parameters that given above. The construction of software and hardware of the control system is introduced. And target image of underwater distance 25 m and 40m is given, Experimental results showed that the control system has high control precision, safe and stable operation and good speed adjusting performance can be achieved. It can be satisfied to apply to underwater target detection.

  8. Design and implementation of control system for range-gated underwater laser imaging

    NASA Astrophysics Data System (ADS)

    Ge, Wei-long; Zhang, Xiao-hui; Han, Hong-wei; Hua, Liang-hong

    2012-01-01

    There is currently considerable in developing underwater target detection, the underwater imaging system can be divided into active imaging system and passive system. The main feature of the active imaging system is that they use light sources to illuminate the targets and collect the reflection from targets. The advantages of active imaging system over passive imaging systems are high contrast and without the affection of environment sources. In this article, a range-gated underwater laser imaging system is built, which consists of laser illumination system, photoelectric imaging system and control system. The laser illumination system includes a light-pumped solid state doubled ND-YAG laser(532nm) which laser power and frequency can be adjusted and an optics expanding system of variable ratio. The photoelectric imaging system includes a gated Intensified CCD(ICCD) cameras which ICCD scheduling, gate width, delay time and gain can be adjusted and a optics received system of variable ratio. In order to acquire effectual target image using range-gated underwater laser imaging system, appropriate control parameters that include laser power and frequency, ICCD scheduling, gate width, delay time and gain, optics expanding system ratio and optics received system ratio must be given accurately. A control system which used C8051F320 and C8051F040 (MCU) as the core is designed, the control system can effectively control seven parameters that given above. The construction of software and hardware of the control system is introduced. And target image of underwater distance 25 m and 40m is given, Experimental results showed that the control system has high control precision, safe and stable operation and good speed adjusting performance can be achieved. It can be satisfied to apply to underwater target detection.

  9. Hepatic mTORC1 controls locomotor activity, body temperature, and lipid metabolism through FGF21.

    PubMed

    Cornu, Marion; Oppliger, Wolfgang; Albert, Verena; Robitaille, Aaron M; Trapani, Francesca; Quagliata, Luca; Fuhrer, Tobias; Sauer, Uwe; Terracciano, Luigi; Hall, Michael N

    2014-08-12

    The liver is a key metabolic organ that controls whole-body physiology in response to nutrient availability. Mammalian target of rapamycin (mTOR) is a nutrient-activated kinase and central controller of growth and metabolism that is negatively regulated by the tumor suppressor tuberous sclerosis complex 1 (TSC1). To investigate the role of hepatic mTOR complex 1 (mTORC1) in whole-body physiology, we generated liver-specific Tsc1 (L-Tsc1 KO) knockout mice. L-Tsc1 KO mice displayed reduced locomotor activity, body temperature, and hepatic triglyceride content in a rapamycin-sensitive manner. Ectopic activation of mTORC1 also caused depletion of hepatic and plasma glutamine, leading to peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α)-dependent fibroblast growth factor 21 (FGF21) expression in the liver. Injection of glutamine or knockdown of PGC-1α or FGF21 in the liver suppressed the behavioral and metabolic defects due to mTORC1 activation. Thus, mTORC1 in the liver controls whole-body physiology through PGC-1α and FGF21. Finally, mTORC1 signaling correlated with FGF21 expression in human liver tumors, suggesting that treatment of glutamine-addicted cancers with mTOR inhibitors might have beneficial effects at both the tumor and whole-body level.

  10. Hepatic mTORC1 controls locomotor activity, body temperature, and lipid metabolism through FGF21

    PubMed Central

    Cornu, Marion; Oppliger, Wolfgang; Albert, Verena; Robitaille, Aaron M.; Trapani, Francesca; Quagliata, Luca; Fuhrer, Tobias; Sauer, Uwe; Terracciano, Luigi; Hall, Michael N.

    2014-01-01

    The liver is a key metabolic organ that controls whole-body physiology in response to nutrient availability. Mammalian target of rapamycin (mTOR) is a nutrient-activated kinase and central controller of growth and metabolism that is negatively regulated by the tumor suppressor tuberous sclerosis complex 1 (TSC1). To investigate the role of hepatic mTOR complex 1 (mTORC1) in whole-body physiology, we generated liver-specific Tsc1 (L-Tsc1 KO) knockout mice. L-Tsc1 KO mice displayed reduced locomotor activity, body temperature, and hepatic triglyceride content in a rapamycin-sensitive manner. Ectopic activation of mTORC1 also caused depletion of hepatic and plasma glutamine, leading to peroxisome proliferator–activated receptor γ coactivator-1α (PGC-1α)–dependent fibroblast growth factor 21 (FGF21) expression in the liver. Injection of glutamine or knockdown of PGC-1α or FGF21 in the liver suppressed the behavioral and metabolic defects due to mTORC1 activation. Thus, mTORC1 in the liver controls whole-body physiology through PGC-1α and FGF21. Finally, mTORC1 signaling correlated with FGF21 expression in human liver tumors, suggesting that treatment of glutamine-addicted cancers with mTOR inhibitors might have beneficial effects at both the tumor and whole-body level. PMID:25082895

  11. The role of leg touchdown for the control of locomotor activity in the walking stick insect

    PubMed Central

    Schmitz, Joscha; Büschges, Ansgar

    2015-01-01

    Much is known on how select sensory feedback contributes to the activation of different motoneuron pools in the locomotor control system of stick insects. However, even though activation of the stance phase muscles depressor trochanteris, retractor unguis, flexor tibiae and retractor coxae is correlated with the touchdown of the leg, the potential sensory basis of this correlation or its connection to burst intensity remains unknown. In our experiments, we are using a trap door setup to investigate how ground contact contributes to stance phase muscle activation and burst intensity in different stick insect species, and which afferent input is involved in the respective changes. While the magnitude of activation is changed in all of the above stance phase muscles, only the timing of the flexor tibiae muscle is changed if the animal unexpectedly steps into a hole. Individual and combined ablation of different force sensors on the leg demonstrated influence from femoral campaniform sensilla on flexor muscle timing, causing a significant increase in the latencies during control and air steps. Our results show that specific load feedback signals determine the timing of flexor tibiae activation at the swing-to-stance transition in stepping stick insects, but that additional feedback may also be involved in flexor muscle activation during stick insect locomotion. With respect to timing, all other investigated stance phase muscles appear to be under sensory control other than that elicited through touchdown. PMID:25652931

  12. EFFECT OF SEX, AGE, AND BMI ON THE DEVELOPMENT OF LOCOMOTOR SKILLS AND OBJECT CONTROL SKILLS AMONG PRESCHOOL CHILDREN.

    PubMed

    Yang, Shu-Chu; Lin, Shu-Jung; Tsai, Chia-Yen

    2015-12-01

    Purposive sampling was used to recruit 1,200 preschoolers between the ages of three and seven from 12 preschools throughout Taiwan in order to examine locomotor skills, object control skills, and fundamental motor skills with respect to sex, age, and body mass index (BMI). Fundamental motor skills were measured using the TGMD-2. Only age had a significant influence on locomotor skills, object control skills, and fundamental motor skills; sex had a small influence on object control skills, and BMI had a very limited influence on all three categories. The difference from previous studies related to BMI may be due to the different items included in the various tests, the number of trials conducted, and ways in which BMI was categorized.

  13. When wings touch wakes: understanding locomotor force control by wake wing interference in insect wings.

    PubMed

    Lehmann, Fritz-Olaf

    2008-01-01

    Understanding the fluid dynamics of force control in flying insects requires the exploration of how oscillating wings interact with the surrounding fluid. The production of vorticity and the shedding of vortical structures within the stroke cycle thus depend on two factors: the temporal structure of the flow induced by the wing's own instantaneous motion and the flow components resulting from both the force production in previous wing strokes and the motion of other wings flapping in close proximity. These wake-wing interactions may change on a stroke-by-stroke basis, confronting the neuro-muscular system of the animal with a complex problem for force control. In a single oscillating wing, the flow induced by the preceding half stroke may lower the wing's effective angle of attack but permits the recycling of kinetic energy from the wake via the wake capture mechanism. In two-winged insects, the acceleration fields produced by each wing may strongly interact via the clap-and-fling mechanism during the dorsal stroke reversal. Four-winged insects must cope with the fact that the flow over their hindwings is affected by the presence of the forewings. In these animals, a phase-shift between the stroke cycles of fore- and hindwing modulates aerodynamic performance of the hindwing via leading edge vortex destruction and changes in local flow condition including wake capture. Moreover, robotic wings demonstrate that phase-lag during peak performance and the strength of force modulation depend on the vertical spacing between the two stroke planes and the size ratio between fore- and hindwing. This study broadly summarizes the most prominent mechanisms of wake-wing and wing-wing interactions found in flapping insect wings and evaluates the consequences of these processes for the control of locomotor forces in the behaving animal.

  14. Experimental investigations of the controlled motion of a screwless underwater robot

    NASA Astrophysics Data System (ADS)

    Karavaev, Yury L.; Kilin, Alexander A.; Klekovkin, Anton V.

    2016-12-01

    In this paper we describe the results of experimental investigations of the motion of a screwless underwater robot controlled by rotating internal rotors. We present the results of comparison of the trajectories obtained with the results of numerical simulation using the model of an ideal fluid.

  15. Plasticity and modular control of locomotor patterns in neurological disorders with motor deficits

    PubMed Central

    Ivanenko, Y. P.; Cappellini, G.; Solopova, I. A.; Grishin, A. A.; MacLellan, M. J.; Poppele, R. E.; Lacquaniti, F.

    2013-01-01

    Human locomotor movements exhibit considerable variability and are highly complex in terms of both neural activation and biomechanical output. The building blocks with which the central nervous system constructs these motor patterns can be preserved in patients with various sensory-motor disorders. In particular, several studies highlighted a modular burst-like organization of the muscle activity. Here we review and discuss this issue with a particular emphasis on the various examples of adaptation of locomotor patterns in patients (with large fiber neuropathy, amputees, stroke and spinal cord injury). The results highlight plasticity and different solutions to reorganize muscle patterns in both peripheral and central nervous system lesions. The findings are discussed in a general context of compensatory gait mechanisms, spatiotemporal architecture and modularity of the locomotor program. PMID:24032016

  16. Modeling and control of an unmanned underwater vehicle using a mass moving system

    NASA Astrophysics Data System (ADS)

    Byun, Seung-Woo; Kim, Donghee; Choi, Hyeung-Sik; Kim, Joon-Young

    2015-03-01

    This paper describes the mathematical modeling and control algorithms of an unmanned underwater vehicle (UUV) named Minekiller. This UUV has two longitudinal thrusters, one vertical thruster, and an internal mass moving system, which can control the pitch rate. The UUV is equipped with a movable mass for pitch control. It is different from other common UUVs, in that it can maintain a static pitch angle. The UUV's 6-DOF (Degrees of Freedom) dynamics model is derived from the hydrodynamic forces and moments acting on it. We applied these hydrodynamic coefficients to dynamic modeling for numerical simulations by MATLAB/SIMULINK©. To compare the performance in various cases, we used a PID controller for depth and heading control. Also, the navigation controller can analyze the way-point tracking performance. These simulation results show the performance of the control algorithms and maneuvering performance of the underwater vehicle.

  17. Advanced Non-Linear Control Algorithms Applied to Design Highly Maneuverable Autonomous Underwater Vehicles (AUVs)

    DTIC Science & Technology

    2007-08-01

    Advanced non- linear control algorithms applied to design highly maneuverable Autonomous Underwater Vehicles (AUVs) Vladimir Djapic, Jay A. Farrell...hierarchical such that an ”inner loop” non- linear controller (outputs the appropriate thrust values) is the same for all mission scenarios while a...library of ”outer-loop” non- linear controllers are available to implement specific maneuvering scenarios. On top of the outer-loop is the mission planner

  18. A Hypothetical Perspective on the Relative Contributions of Strategic and Adaptive Control Mechanisms in Plastic Recalibration of Locomotor Heading Direction

    NASA Technical Reports Server (NTRS)

    Richards, J. T.; Mulavara, A. P.; Ruttley, T.; Peters, B. T.; Warren, L. E.; Bloomberg, J. J.

    2006-01-01

    We have previously shown that viewing simulated rotary self-motion during treadmill locomotion causes adaptive modification of the control of position and trajectory during over-ground locomotion, which functionally reflects adaptive changes in the sensorimotor integration of visual, vestibular, and proprioceptive cues (Mulavara et al., 2005). The objective of this study was to investigate how strategic changes in torso control during exposure to simulated rotary self-motion during treadmill walking influences adaptive modification of locomotor heading direction during over-ground stepping.

  19. Locomotor exercise in weightlessness

    NASA Technical Reports Server (NTRS)

    Thornton, W.; Whitmore, H.

    1991-01-01

    The requirements for exercise in space by means of locomotion are established and addressed with prototype treadmills for use during long-duration spaceflight. The adaptation of the human body to microgravity is described in terms of 1-G locomotor biomechanics, the effects of reduced activity, and effective activity-replacement techniques. The treadmill is introduced as a complement to other techniques of force replacement with reference given to the angle required for exercise. A motor-driven unit is proposed that can operate at a variety of controlled speeds and equivalent grades. The treadmills permit locomotor exercise as required for long-duration space travel to sustain locomotor and cardiorespiratory capacity at a level consistent with postflight needs.

  20. Admixture enhanced controlled low-strength material for direct underwater injection with minimal cross-contamination

    SciTech Connect

    Hepworth, H.K.; Davidson, J.S.; Hooyman, J.L.

    1997-03-01

    Commercially available admixtures have been developed for placing traditional concrete products under water. This paper evaluates adapting anti-washout admixture (AWA) and high range water reducing admixture (HRWRA) products to enhance controlled low-strength materials (CLSMs) for underwater placement. A simple experimental scale model (based on dynamic and geometric similitude) of typical grout pump emplacement equipment has been developed to determine the percentage of cementing material washed out. The objective of this study was to identify proportions of admixtures and underwater CLSM emplacement procedures which would minimize the cross-contamination of the displaced water while maintaining the advantages of CLSM. Since the displaced water from radioactively contaminated systems must be subsequently treated prior to release to the environment, the amount of cross-contamination is important for cases in which cementing material could form hard sludges in a water treatment facility and contaminate the in-place CLSM stabilization medium.

  1. Remote-Controlled Inspection Robot for Nuclear Facilities in Underwater Environment

    SciTech Connect

    Yasuhiro Miwa; Syuichi Satoh; Naoya Hirose

    2002-07-01

    A remote-controlled inspection robot for nuclear facilities was developed. This is a underwater robot technology combined with inspection and flaw removal technologies. This report will describe the structure and performance of this robot. The inspection robot consists of two parts. The one is driving equipment, and the other is inspection and grinding units. It can swim in the tank, move around the tank wall, and stay on the inspection area. After that it starts inspection and flaw removal with a special grinding wheel. This technology had been developed to inspect some Radioactive Waste (RW) tanks in operating nuclear power plants. There are many RW tanks in these plants, which human workers can be hard to access because of a high level dose. This technology is too useful for inspection works of human-inaccessible areas. And also, in conventional inspection process, some worker go into the tank and set up scaffolding after full drainage and decontamination. It spends too much time for these preparations. If tank inspection and flaw removal can be performed in underwater, the outage period will be reduced. Remote-controlled process can be performed in underwater. This is the great advantage for plant owners. Since 1999 we have been applying this inspection robot to operating nuclear 11 facilities in Japan. (authors)

  2. Supervisory Control of Underwater Telemanipulators: Design and Experiment.

    DTIC Science & Technology

    1982-08-30

    control ........ 61 3.6 Descriptions for process level control ......... 67 Chapter 4 The design of a software man-machine interface...different types of human oriented interfaces for achieving such control will be presented. 4. The design of a new man-machine interface system intended 11...under the direction of a human operator [6]. Supervisory control fits on a continuum between manually controlled

  3. Real Time Adaptive Control of an Autonomous Underwater Vehicle (AUV)

    DTIC Science & Technology

    1989-09-01

    design of a control system f or the AUV, since knowledge of an accurate dynamic model is in general the basis of a reliable control design. Also, tests...designer the possibility of using this simple nominal model, possibly linear while still preserving the global stability ol. he controlled system . 3...control system . The parameters a, c arid K0 in (2.4a) depend on the operating 9 conditions (speed, primarily) of the vehicle, and can be determined on the

  4. A controlled laboratory environment to study EO signal degradation due to underwater turbulence

    NASA Astrophysics Data System (ADS)

    Matt, Silvia; Hou, Weilin; Goode, Wesley; Liu, Guigen; Han, Ming; Kanaev, Andrey; Restaino, Sergio

    2015-05-01

    Temperature microstructure in the ocean can lead to localized changes in the index of refraction and can distort underwater electro-optical (EO) signal transmission. A similar phenomenon is well-known from atmospheric optics and generally referred to as "optical turbulence". Though turbulent fluctuations in the ocean distort EO signal transmission and can impact various underwater applications, from diver visibility to active and passive remote sensing, there have been few studies investigating the subject. To provide a test bed for the study of impacts from turbulent flows on underwater EO signal transmission, and to examine and mitigate turbulence effects, we set up a laboratory turbulence environment allowing the variation of turbulence intensity. Convective turbulence is generated in a large Rayleigh- Bénard tank and the turbulent flow is quantified using high-resolution Acoustic Doppler Velocimeter profilers and fast thermistor probes. The turbulence measurements are complemented by computational fluid dynamics simulations of convective turbulence emulating the tank environment. These numerical simulations supplement the sparse laboratory measurements. The numerical data compared well to the laboratory data and both conformed to the Kolmogorov spectrum of turbulence and the Batchelor spectrum of temperature fluctuations. The controlled turbulence environment can be used to assess optical image degradation in the tank in relation to turbulence intensity, as well as to apply adaptive optics techniques. This innovative approach that combines optical techniques, turbulence measurements and numerical simulations can help understand how to mitigate the effects of turbulence impacts on underwater optical signal transmission, as well as advance optical techniques to probe oceanic processes.

  5. Biomimetic approaches to the control of underwater walking machines.

    PubMed

    Ayers, Joseph; Witting, Jan

    2007-01-15

    We have developed a biomimetic robot based on the American lobster. The robot is designed to achieve the performance advantages of the animal model by adopting biomechanical features and neurobiological control principles. Three types of controllers are described. The first is a state machine based on the connectivity and dynamics of the lobster central pattern generator (CPG). The state machine controls myomorphic actuators based on shape memory alloys (SMAs) and responds to environmental perturbation through sensors that employ a labelled-line code. The controller supports a library of action patterns and exteroceptive reflexes to mediate tactile navigation, obstacle negotiation and adaptation to surge. We are extending this controller to neuronal network-based models. A second type of leg CPG is based on synaptic networks of electronic neurons and has been adapted to control the SMA actuated leg. A brain is being developed using layered reflexes based on discrete time map-based neurons.

  6. Research on framework for formation control of multiple underwater robots in a dynamic environment

    NASA Astrophysics Data System (ADS)

    Meng, Xian-Song; Xu, Hong-Gen; Zhang, Ming-Jun

    2004-12-01

    In this paper a practical framework is proposed to keep formation control of multiple underwater robots in a dynamic environment. The approach is a viable solution to solve formation problem. The approach allows online planning of the formation paths using a Dijkstra’s search algorithm based on the current sensor data. The formation is allowed to be dynamically changed in order to avoid obstacles in the environment. A controller is designed to keep the robots in their planned trajectories. It is shown that the approach is effective and feasible by the simulation of computer.

  7. Communication and Control for Fleets of Autonomous Underwater Vehicles

    DTIC Science & Technology

    2006-10-30

    Figure 2. In addition, we have shown that a leader - follower platoon formation is inherently stable where the leader continuously broadcasts its...also demonstrated for this leader - follower platoon formation. RESULTS We changed a formation control problem into a formation regulation problem and...of unstable fixed modes. It was also shown that the stability of the n- vehicle leader - follower system was achieved by stabilizing each vehicle

  8. Leptin-Dependent Control of Glucose Balance and Locomotor Activity by POMC Neurons

    PubMed Central

    Huo, Lihong; Gamber, Kevin; Greeley, Sarah; Silva, Jose; Huntoon, Nicholas; Leng, Xinghong; Bjørbæk, Christian

    2009-01-01

    Summary Leptin plays a pivotal role in regulation of energy balance. Via unknown central pathways leptin also affects peripheral glucose homeostasis and locomotor activity. We hypothesized that specifically Pro-opiomelanocortin (POMC) neurons mediate those actions. To examine this possibility we applied Cre-Lox technology to express leptin receptors (ObRb) exclusively in POMC neurons of the morbidly obese, profoundly diabetic, and severely hypoactive leptin receptor deficient Leprdb/db mice. We here show that expression of ObRb only in POMC neurons leads to a marked decrease in energy intake and a modest reduction in body weight in Leprdb/db mice. Remarkably, blood glucose levels are entirely normalized. This normalization occurs independently of changes in food intake and body weight. In addition, physical activity is greatly increased despite profound obesity. Our results suggest that leptin signaling exclusively in POMC neurons is sufficient to stimulate locomotion and prevent diabetes in the severely hypoactive and hyperglycemic obese Leprdb/db mice. PMID:19490908

  9. Mouse aldehyde-oxidase-4 controls diurnal rhythms, fat deposition and locomotor activity

    PubMed Central

    Terao, Mineko; Barzago, Maria Monica; Kurosaki, Mami; Fratelli, Maddalena; Bolis, Marco; Borsotti, Andrea; Bigini, Paolo; Micotti, Edoardo; Carli, Mirjana; Invernizzi, Roberto William; Bagnati, Renzo; Passoni, Alice; Pastorelli, Roberta; Brunelli, Laura; Toschi, Ivan; Cesari, Valentina; Sanoh, Seigo; Garattini, Enrico

    2016-01-01

    Aldehyde-oxidase-4 (AOX4) is one of the mouse aldehyde oxidase isoenzymes and its physiological function is unknown. The major source of AOX4 is the Harderian-gland, where the enzyme is characterized by daily rhythmic fluctuations. Deletion of the Aox4 gene causes perturbations in the expression of the circadian-rhythms gene pathway, as indicated by transcriptomic analysis. AOX4 inactivation alters the diurnal oscillations in the expression of master clock-genes. Similar effects are observed in other organs devoid of AOX4, such as white adipose tissue, liver and hypothalamus indicating a systemic action. While perturbations of clock-genes is sex-independent in the Harderian-gland and hypothalamus, sex influences this trait in liver and white-adipose-tissue which are characterized by the presence of AOX isoforms other than AOX4. In knock-out animals, perturbations in clock-gene expression are accompanied by reduced locomotor activity, resistance to diet induced obesity and to hepatic steatosis. All these effects are observed in female and male animals. Resistance to obesity is due to diminished fat accumulation resulting from increased energy dissipation, as white-adipocytes undergo trans-differentiation towards brown-adipocytes. Metabolomics and enzymatic data indicate that 5-hydroxyindolacetic acid and tryptophan are novel endogenous AOX4 substrates, potentially involved in AOX4 systemic actions. PMID:27456060

  10. Intelligent Co-ordinate control for mating process of underwater vehicle based on TFPN

    NASA Astrophysics Data System (ADS)

    Yan, Zhe-Ping; Dai, Xue-Feng; Bian, Xin-Qian

    2002-12-01

    In order to reduce time and improve the probability of successful matting it is useful to co-ordinate between the movement control and mating process of the underwater vehicle. Because it is hard to control with the common method under the condition of mating process, the hierarchical intelligent control is introduced. Timed fuzzy Petri net (TFPN), which is the integration of PN and fuzzy reasoning, is used in the design of coordinate level of hierarchically intelligent control. It made the control process better in reflecting the characteristics of time-driven, event-driven, fuzzy information and so on. The test shows that TF-PN could shorten the time of mating and enhance the efficiency.

  11. EFPC: An Environmentally Friendly Power Control Scheme for Underwater Sensor Networks.

    PubMed

    Yang, Qiuling; Su, Yishan; Jin, Zhigang; Yao, Guidan

    2015-11-17

    In oceans, the limited acoustic spectrum resource is heavily shared by marine mammals and manmade systems including underwater sensor networks. In order to limit the negative impact of acoustic signal on marine mammals, we propose an environmentally friendly power control (EFPC) scheme for underwater sensor networks. EFPC allocates transmission power of sensor nodes with a consideration of the existence of marine mammals. By applying a Nash Equilibrium based utility function with a set of limitations to optimize transmission power, the proposed power control algorithm can conduct parallel transmissions to improve the network's goodput, while avoiding interference with marine mammals. Additionally, to localize marine mammals, which is a prerequisite of EFPC, we propose a novel passive hyperboloid localization algorithm (PHLA). PHLA passively localize marine mammals with the help of the acoustic characteristic of these targets. Simulation results show that PHLA can localize most of the target with a relatively small localization error and EFPC can achieve a close goodput performance compared with an existing power control algorithm while avoiding interfering with marine mammals.

  12. EFPC: An Environmentally Friendly Power Control Scheme for Underwater Sensor Networks

    PubMed Central

    Yang, Qiuling; Su, Yishan; Jin, Zhigang; Yao, Guidan

    2015-01-01

    In oceans, the limited acoustic spectrum resource is heavily shared by marine mammals and manmade systems including underwater sensor networks. In order to limit the negative impact of acoustic signal on marine mammals, we propose an environmentally friendly power control (EFPC) scheme for underwater sensor networks. EFPC allocates transmission power of sensor nodes with a consideration of the existence of marine mammals. By applying a Nash Equilibrium based utility function with a set of limitations to optimize transmission power, the proposed power control algorithm can conduct parallel transmissions to improve the network’s goodput, while avoiding interference with marine mammals. Additionally, to localize marine mammals, which is a prerequisite of EFPC, we propose a novel passive hyperboloid localization algorithm (PHLA). PHLA passively localize marine mammals with the help of the acoustic characteristic of these targets. Simulation results show that PHLA can localize most of the target with a relatively small localization error and EFPC can achieve a close goodput performance compared with an existing power control algorithm while avoiding interfering with marine mammals. PMID:26593922

  13. Remote full control, by an Internet link, of an underwater acoustics laboratory

    NASA Astrophysics Data System (ADS)

    Ranz-Guerra, Carlos; Cobo-Parra, Pedro; Siguero-Guerra, Manuel; Fernandez-Fernandez, Alejandro

    2002-11-01

    The Underwater Tank Laboratory located at the Instituto de Acustica, CSIC, Madrid, has been fully reshaped. Now, the two bridges (emission and reception) have full automatic motion control by the operator. These capabilities were complemented by a new management of signal generation, signal acquisition, processing and storing of data. This new framework makes many of the tasks to be performed in this kind of facility easier by putting at the hands of the operator specific friendly software programs that attend to the main aspects of the ongoing experiment. In one step forward, the remote control of all the functionalities was considered feasible. The potentialities of the Internet were thought to provide a new dimension to the laboratory by lowering the difficulties of taking over the full control of the installation, by any user around the world. Here is one real example of how this achievement can be carried out. The Underwater Acoustics Laboratory at the Instituto de Acustica, CSIC, is now ready to be run by any one interested. The main lines, over which this problem has been considered, are described in this paper. [Work supported by PN on Science and Technology and CSIC, Spain.

  14. Active control of elastic and rigid body response of a three-dimensional underwater structure

    SciTech Connect

    Suzuki, H.; Yoshida, K.; Watanabe, K.

    1995-02-01

    One key technology for the offshore development of the increasing water depth will be remotely operated installation and construction of flexible structure in the deep water or on the seabed. The flexibility comes from scale-up or weight reduction of the structure. Conventional operation from the sea surfaces is affected by the weather conditions, and, therefore, not so efficient. This paper presents basic research on active control of elastic response and rigid body motion of an underwater elastic structure toward the remotely operated installation technique. The numerical model of the dynamics of the structural model is formulated, and based on the numerical model the control is formulated. The formulated control is tested by computer simulations and model experiments. The structural model is propelled by thrusters and taken from initial position to another position, while the elastic responses are controlled by variable buoyancy-type actuators.

  15. Containment control of networked autonomous underwater vehicles: A predictor-based neural DSC design.

    PubMed

    Peng, Zhouhua; Wang, Dan; Wang, Wei; Liu, Lu

    2015-11-01

    This paper investigates the containment control problem of networked autonomous underwater vehicles in the presence of model uncertainty and unknown ocean disturbances. A predictor-based neural dynamic surface control design method is presented to develop the distributed adaptive containment controllers, under which the trajectories of follower vehicles nearly converge to the dynamic convex hull spanned by multiple reference trajectories over a directed network. Prediction errors, rather than tracking errors, are used to update the neural adaptation laws, which are independent of the tracking error dynamics, resulting in two time-scales to govern the entire system. The stability property of the closed-loop network is established via Lyapunov analysis, and transient property is quantified in terms of L2 norms of the derivatives of neural weights, which are shown to be smaller than the classical neural dynamic surface control approach. Comparative studies are given to show the substantial improvements of the proposed new method.

  16. Postural Control during Upper Body Locomotor-Like Movements: Similar Synergies Based on Dissimilar Muscle Modes

    PubMed Central

    Danna-Dos-Santos, Alessander; Shapkova, Elena Yu.; Shapkova, Alexandra L.; Degani, Adriana M.; Latash, Mark L.

    2009-01-01

    We studied the organization of leg and trunk muscles into groups (M-modes) and co-variation of M-mode involvement (M-mode synergies) during whole-body tasks associated with large variations of the moment of force about the vertical body axis. Our major questions were: (1) Can muscle activation patterns during such tasks be described with a few M-modes common across tasks and subjects? (2) Do these modes form the basis for synergies stabilizing MZ time pattern? (3) Will this organization differ between an explicit body rotation task and a task associated with locomotor-like alternating arm movements? Healthy subjects stood barefoot on the force platform and performed two motor tasks while paced by the metronome at 0.7, 1.0, and 1.4 Hz: Cyclic rotation of the upper body about the vertical body axis (body rotation task), and alternating rhythmic arm movements imitating those during running or quick walking (arm movement task). Principal component analysis was used to identify three M-modes within the space of integrated indices of muscle activity. The M-mode vectors showed clustering neither across subjects nor across frequencies. Variance in the M-mode space across sway cycles was partitioned into two components, one that did not affect the average value of MZ shift ("good variance") and the other that did. An index was computed reflecting the relative amount of the "good variance"; positive values of this index have been interpreted as reflecting a multi-M-mode synergy stabilizing the MZ trajectory. On average, the index was positive for both tasks and across all frequencies studied. However, the magnitude of the index was smaller for the intermediate frequency (1 Hz). The results show that the organization of muscles into groups during relatively complex whole-body tasks can differ significantly across both task variations and subjects. Nevertheless, the central nervous system seems to be able to build MZ stabilizing synergies based on different sets of M

  17. Cerebellum Transcriptome of Mice Bred for High Voluntary Activity Offers Insights into Locomotor Control and Reward-Dependent Behaviors

    PubMed Central

    Caetano-Anollés, Kelsey; Rhodes, Justin S.; Garland, Theodore; Perez, Sam D.; Hernandez, Alvaro G.; Southey, Bruce R.; Rodriguez-Zas, Sandra L.

    2016-01-01

    The role of the cerebellum in motivation and addictive behaviors is less understood than that in control and coordination of movements. High running can be a self-rewarding behavior exhibiting addictive properties. Changes in the cerebellum transcriptional networks of mice from a line selectively bred for High voluntary running (H) were profiled relative to an unselected Control (C) line. The environmental modulation of these changes was assessed both in activity environments corresponding to 7 days of Free (F) access to running wheel and to Blocked (B) access on day 7. Overall, 457 genes exhibited a significant (FDR-adjusted P-value < 0.05) genotype-by-environment interaction effect, indicating that activity genotype differences in gene expression depend on environmental access to running. Among these genes, network analysis highlighted 6 genes (Nrgn, Drd2, Rxrg, Gda, Adora2a, and Rab40b) connected by their products that displayed opposite expression patterns in the activity genotype contrast within the B and F environments. The comparison of network expression topologies suggests that selection for high voluntary running is linked to a predominant dysregulation of hub genes in the F environment that enables running whereas a dysregulation of ancillary genes is favored in the B environment that blocks running. Genes associated with locomotor regulation, signaling pathways, reward-processing, goal-focused, and reward-dependent behaviors exhibited significant genotype-by-environment interaction (e.g. Pak6, Adora2a, Drd2, and Arhgap8). Neuropeptide genes including Adcyap1, Cck, Sst, Vgf, Npy, Nts, Penk, and Tac2 and related receptor genes also exhibited significant genotype-by-environment interaction. The majority of the 183 differentially expressed genes between activity genotypes (e.g. Drd1) were under-expressed in C relative to H genotypes and were also under-expressed in B relative to F environments. Our findings indicate that the high voluntary running mouse

  18. Neural Network-Based Self-Tuning PID Control for Underwater Vehicles

    PubMed Central

    Hernández-Alvarado, Rodrigo; García-Valdovinos, Luis Govinda; Salgado-Jiménez, Tomás; Gómez-Espinosa, Alfonso; Fonseca-Navarro, Fernando

    2016-01-01

    For decades, PID (Proportional + Integral + Derivative)-like controllers have been successfully used in academia and industry for many kinds of plants. This is thanks to its simplicity and suitable performance in linear or linearized plants, and under certain conditions, in nonlinear ones. A number of PID controller gains tuning approaches have been proposed in the literature in the last decades; most of them off-line techniques. However, in those cases wherein plants are subject to continuous parametric changes or external disturbances, online gains tuning is a desirable choice. This is the case of modular underwater ROVs (Remotely Operated Vehicles) where parameters (weight, buoyancy, added mass, among others) change according to the tool it is fitted with. In practice, some amount of time is dedicated to tune the PID gains of a ROV. Once the best set of gains has been achieved the ROV is ready to work. However, when the vehicle changes its tool or it is subject to ocean currents, its performance deteriorates since the fixed set of gains is no longer valid for the new conditions. Thus, an online PID gains tuning algorithm should be implemented to overcome this problem. In this paper, an auto-tune PID-like controller based on Neural Networks (NN) is proposed. The NN plays the role of automatically estimating the suitable set of PID gains that achieves stability of the system. The NN adjusts online the controller gains that attain the smaller position tracking error. Simulation results are given considering an underactuated 6 DOF (degrees of freedom) underwater ROV. Real time experiments on an underactuated mini ROV are conducted to show the effectiveness of the proposed scheme. PMID:27608018

  19. Neural Network-Based Self-Tuning PID Control for Underwater Vehicles.

    PubMed

    Hernández-Alvarado, Rodrigo; García-Valdovinos, Luis Govinda; Salgado-Jiménez, Tomás; Gómez-Espinosa, Alfonso; Fonseca-Navarro, Fernando

    2016-09-05

    For decades, PID (Proportional + Integral + Derivative)-like controllers have been successfully used in academia and industry for many kinds of plants. This is thanks to its simplicity and suitable performance in linear or linearized plants, and under certain conditions, in nonlinear ones. A number of PID controller gains tuning approaches have been proposed in the literature in the last decades; most of them off-line techniques. However, in those cases wherein plants are subject to continuous parametric changes or external disturbances, online gains tuning is a desirable choice. This is the case of modular underwater ROVs (Remotely Operated Vehicles) where parameters (weight, buoyancy, added mass, among others) change according to the tool it is fitted with. In practice, some amount of time is dedicated to tune the PID gains of a ROV. Once the best set of gains has been achieved the ROV is ready to work. However, when the vehicle changes its tool or it is subject to ocean currents, its performance deteriorates since the fixed set of gains is no longer valid for the new conditions. Thus, an online PID gains tuning algorithm should be implemented to overcome this problem. In this paper, an auto-tune PID-like controller based on Neural Networks (NN) is proposed. The NN plays the role of automatically estimating the suitable set of PID gains that achieves stability of the system. The NN adjusts online the controller gains that attain the smaller position tracking error. Simulation results are given considering an underactuated 6 DOF (degrees of freedom) underwater ROV. Real time experiments on an underactuated mini ROV are conducted to show the effectiveness of the proposed scheme.

  20. Design and Initial In-Water Testing of Advanced Non-Linear Control Algorithms onto an Unmanned Underwater Vehicle (UUV)

    DTIC Science & Technology

    2007-10-01

    Design and initial in-water testing of advanced non- linear control algorithms onto an Unmanned Underwater Vehicle (UUV) Vladimir Djapic Unmanned...attitude or translating in a direction different from that of the surface. Non- linear controller that compensates for non-linear forces (such as drag...loop” non- linear controller (outputs the appropriate thrust values) is the same for all mission scenarios while an appropriate ”outer-loop” non

  1. Locomotor Expertise Predicts Infants' Perseverative Errors

    ERIC Educational Resources Information Center

    Berger, Sarah E.

    2010-01-01

    This research examined the development of inhibition in a locomotor context. In a within-subjects design, infants received high- and low-demand locomotor A-not-B tasks. In Experiment 1, walking 13-month-old infants followed an indirect path to a goal. In a control condition, infants took a direct route. In Experiment 2, crawling and walking…

  2. Output Feedback Fractional-Order Nonsingular Terminal Sliding Mode Control of Underwater Remotely Operated Vehicles

    PubMed Central

    Chen, Jiawang; Gu, Linyi

    2014-01-01

    For the 4-DOF (degrees of freedom) trajectory tracking control problem of underwater remotely operated vehicles (ROVs) in the presence of model uncertainties and external disturbances, a novel output feedback fractional-order nonsingular terminal sliding mode control (FO-NTSMC) technique is introduced in light of the equivalent output injection sliding mode observer (SMO) and TSMC principle and fractional calculus technology. The equivalent output injection SMO is applied to reconstruct the full states in finite time. Meanwhile, the FO-NTSMC algorithm, based on a new proposed fractional-order switching manifold, is designed to stabilize the tracking error to equilibrium points in finite time. The corresponding stability analysis of the closed-loop system is presented using the fractional-order version of the Lyapunov stability theory. Comparative numerical simulation results are presented and analyzed to demonstrate the effectiveness of the proposed method. Finally, it is noteworthy that the proposed output feedback FO-NTSMC technique can be used to control a broad range of nonlinear second-order dynamical systems in finite time. PMID:24983004

  3. Striatopallidal Neuron NMDA Receptors Control Synaptic Connectivity, Locomotor, and Goal-Directed Behaviors

    PubMed Central

    Lambot, Laurie; Chaves Rodriguez, Elena; Houtteman, Delphine; Li, Yuquing; Schiffmann, Serge N.; Gall, David

    2016-01-01

    The basal ganglia (BG) control action selection, motor programs, habits, and goal-directed learning. The striatum, the principal input structure of BG, is predominantly composed of medium-sized spiny neurons (MSNs). Arising from these spatially intermixed MSNs, two inhibitory outputs form two main efferent pathways, the direct and indirect pathways. Striatonigral MSNs give rise to the activating, direct pathway MSNs and striatopallidal MSNs to the inhibitory, indirect pathway (iMSNs). BG output nuclei integrate information from both pathways to fine-tune motor procedures and to acquire complex habits and skills. Therefore, balanced activity between both pathways is crucial for harmonious functions of the BG. Despite the increase in knowledge concerning the role of glutamate NMDA receptors (NMDA-Rs) in the striatum, understanding of the specific functions of NMDA-R iMSNs is still lacking. For this purpose, we generated a conditional knock-out mouse to address the functions of the NMDA-R in the indirect pathway. At the cellular level, deletion of GluN1 in iMSNs leads to a reduction in the number and strength of the excitatory corticostriatopallidal synapses. The subsequent scaling down in input integration leads to dysfunctional changes in BG output, which is seen as reduced habituation, delay in goal-directed learning, lack of associative behavior, and impairment in action selection or skill learning. The NMDA-R deletion in iMSNs causes a decrease in the synaptic strength of striatopallidal neurons, which in turn might lead to a imbalanced integration between direct and indirect MSN pathways, making mice less sensitive to environmental change. Therefore, their ability to learn and adapt to the environment-based experience was significantly affected. SIGNIFICANCE STATEMENT The striatum controls habits, locomotion, and goal-directed behaviors by coordinated activation of two antagonistic pathways. Insofar as NMDA receptors (NMDA-Rs) play a key role in synaptic

  4. A genetically defined asymmetry underlies the inhibitory control of flexor–extensor locomotor movements

    PubMed Central

    Britz, Olivier; Zhang, Jingming; Grossmann, Katja S; Dyck, Jason; Kim, Jun C; Dymecki, Susan; Gosgnach, Simon; Goulding, Martyn

    2015-01-01

    V1 and V2b interneurons (INs) are essential for the production of an alternating flexor–extensor motor output. Using a tripartite genetic system to selectively ablate either V1 or V2b INs in the caudal spinal cord and assess their specific functions in awake behaving animals, we find that V1 and V2b INs function in an opposing manner to control flexor–extensor-driven movements. Ablation of V1 INs results in limb hyperflexion, suggesting that V1 IN-derived inhibition is needed for proper extension movements of the limb. The loss of V2b INs results in hindlimb hyperextension and a delay in the transition from stance phase to swing phase, demonstrating V2b INs are required for the timely initiation and execution of limb flexion movements. Our findings also reveal a bias in the innervation of flexor- and extensor-related motor neurons by V1 and V2b INs that likely contributes to their differential actions on flexion–extension movements. DOI: http://dx.doi.org/10.7554/eLife.04718.001 PMID:26465208

  5. High-brightness organic light-emitting diodes for optogenetic control of Drosophila locomotor behaviour

    NASA Astrophysics Data System (ADS)

    Morton, Andrew; Murawski, Caroline; Pulver, Stefan R.; Gather, Malte C.

    2016-08-01

    Organic light emitting diodes (OLEDs) are in widespread use in today’s mobile phones and are likely to drive the next generation of large area displays and solid-state lighting. Here we show steps towards their utility as a platform technology for biophotonics, by demonstrating devices capable of optically controlling behaviour in live animals. Using devices with a pin OLED architecture, sufficient illumination intensity (0.3 mW.mm‑2) to activate channelrhodopsins (ChRs) in vivo was reliably achieved at low operating voltages (5 V). In Drosophila melanogaster third instar larvae expressing ChR2(H134R) in motor neurons, we found that pulsed illumination from blue and green OLEDs triggered robust and reversible contractions in animals. This response was temporally coupled to the timing of OLED illumination. With blue OLED illumination, the initial rate and overall size of the behavioural response was strongest. Green OLEDs achieved roughly 70% of the response observed with blue OLEDs. Orange OLEDs did not produce contractions in larvae, in agreement with the spectral response of ChR2(H134R). The device configuration presented here could be modified to accommodate other small model organisms, cell cultures or tissue slices and the ability of OLEDs to provide patterned illumination and spectral tuning can further broaden their utility in optogenetics experiments.

  6. High-brightness organic light-emitting diodes for optogenetic control of Drosophila locomotor behaviour

    PubMed Central

    Morton, Andrew; Murawski, Caroline; Pulver, Stefan R.; Gather, Malte C.

    2016-01-01

    Organic light emitting diodes (OLEDs) are in widespread use in today’s mobile phones and are likely to drive the next generation of large area displays and solid-state lighting. Here we show steps towards their utility as a platform technology for biophotonics, by demonstrating devices capable of optically controlling behaviour in live animals. Using devices with a pin OLED architecture, sufficient illumination intensity (0.3 mW.mm−2) to activate channelrhodopsins (ChRs) in vivo was reliably achieved at low operating voltages (5 V). In Drosophila melanogaster third instar larvae expressing ChR2(H134R) in motor neurons, we found that pulsed illumination from blue and green OLEDs triggered robust and reversible contractions in animals. This response was temporally coupled to the timing of OLED illumination. With blue OLED illumination, the initial rate and overall size of the behavioural response was strongest. Green OLEDs achieved roughly 70% of the response observed with blue OLEDs. Orange OLEDs did not produce contractions in larvae, in agreement with the spectral response of ChR2(H134R). The device configuration presented here could be modified to accommodate other small model organisms, cell cultures or tissue slices and the ability of OLEDs to provide patterned illumination and spectral tuning can further broaden their utility in optogenetics experiments. PMID:27484401

  7. Enhancement of Contralesional Motor Control Promotes Locomotor Recovery after Unilateral Brain Lesion

    PubMed Central

    Hua, Xu-Yun; Qiu, Yan-Qun; Wang, Meng; Zheng, Mou-Xiong; Li, Tie; Shen, Yun-Dong; Jiang, Su; Xu, Jian-Guang; Gu, Yu-Dong; Tsien, JoeZ.; Xu, Wen-Dong

    2016-01-01

    There have been controversies on the contribution of contralesional hemispheric compensation to functional recovery of the upper extremity after a unilateral brain lesion. Some studies have demonstrated that contralesional hemispheric compensation may be an important recovery mechanism. However, in many cases where the hemispheric lesion is large, this form of compensation is relatively limited, potentially due to insufficient connections from the contralesional hemisphere to the paralyzed side. Here, we used a new procedure to increase the effect of contralesional hemispheric compensation by surgically crossing a peripheral nerve at the neck in rats, which may provide a substantial increase in connections between the contralesional hemisphere and the paralyzed limb. This surgical procedure, named cross-neck C7-C7 nerve transfer, involves cutting the C7 nerve on the healthy side and transferring it to the C7 nerve on the paretic side. Intracortical microstimulation, Micro-PET and histological analysis were employed to explore the cortical changes in contralesional hemisphere and to reveal its correlation with behavioral recovery. These results showed that the contralesional hemispheric compensation was markedly strengthened and significantly related to behavioral improvements. The findings also revealed a feasible and effective way to maximize the potential of one hemisphere in controlling both limbs. PMID:26732072

  8. Underwater manipulator

    DOEpatents

    Schrum, P.B.; Cohen, G.H.

    1993-04-20

    Self-contained, waterproof, water-submersible, remote-controlled apparatus is described for manipulating a device, such as an ultrasonic transducer for measuring crack propagation on an underwater specimen undergoing shock testing. The subject manipulator includes metal bellows for transmittal of angular motions without the use of rotating shaft seals or O-rings. Inside the manipulator, a first stepper motor controls angular movement. In the preferred embodiment, the bellows permit the first stepper motor to move an ultrasonic transducer [plus minus]45 degrees in a first plane and a second bellows permit a second stepper motor to move the transducer [plus minus]10 degrees in a second plane orthogonal to the first. In addition, an XY motor-driven table provides XY motion.

  9. Underwater manipulator

    DOEpatents

    Schrum, Phillip B.; Cohen, George H.

    1993-01-01

    Self-contained, waterproof, water-submersible, remote-controlled apparatus is provided for manipulating a device, such as an ultrasonic transducer for measuring crack propagation on an underwater specimen undergoing shock testing. The subject manipulator includes metal bellows for transmittal of angular motions without the use of rotating shaft seals or O-rings. Inside the manipulator, a first stepper motor controls angular movement. In the preferred embodiment, the bellows permit the first stepper motor to move an ultrasonic transducer .+-.45 degrees in a first plane and a second bellows permit a second stepper motor to move the transducer .+-.10 degrees in a second plane orthogonal to the first. In addition, an XY motor-driven table provides XY motion.

  10. Underwater manipulator

    SciTech Connect

    Schrum, P.B.; Cohen, G.H.

    1992-12-31

    This invention is comprised of a self-contained, waterproof, water-submersible, remote-controlled apparatus provided for manipulating a device, such as an ultrasonic transducer for measuring crack propagation on an underwater specimen undergoing shock testing. The subject manipulator includes metal bellows for transmittal of angular motions without the use of rotating shaft seals or O-rings. Inside the manipulator, a first stepper motor controls angular movement. In the preferred embodiment, the bellows permit the first stepper motor to move an ultrasonic transducer {plus_minus} 45 degrees in a first plane and a second bellows permit a second stepper motor to move the transducer {plus_minus} 10 degrees in a second plane orthogonal to the first. In addition, an XY motor-driven table provides XY motion.

  11. Communications and Control for Enhanced Autonomy in Underwater Vehicles for Deep Oceanographic Research

    NASA Astrophysics Data System (ADS)

    Jakuba, M.; Kinsey, J. C.; Yoerger, D. R.; Whitcomb, L. L.; Camilli, R.; Murphy, C.; Bowen, A.; German, C. R.

    2010-12-01

    NASA’s Astrobiology Science and Technology for Exploring Planets (ASTEP) program is a science-driven program to produce advances in scientific and technological capabilities for planetary exploration. Oceanographic robotic vehicles and planetary exploration robots have proven to be highly effective scientific tools for performing scientific research in remote, extreme, and hostile environments that preclude direct human presence. In both domains, the planets and the world’s oceans, human oversight of remote robotic exploration can dramatically enhance scientific return in comparison to purely pre-planned missions by combining the perception, intelligence, and domain knowledge of the human operators with the super-human physical and sensory capabilities of robots. The degree of human oversight, however, is restricted in sea and space by physical limits on the bandwidth and time delay of communications between human operators and remote robotic platforms. Enhanced robotic autonomy can alleviate this obstacle. We present a communications and control architecture for underwater oceanographic robot vehicles that has permitted us to introduce elements of enhanced autonomy into operations with the Woods Hole Oceanographic Institution's Autonomous Underwater Vehicles (AUVs) Nereus and Sentry. Our architecture is designed to facilitate: (1) autonomous distillation of scientific data and transmission of salient synopses from the remote vehicle to its human operators; (2) high-level near real-time human supervision and control of mission programming; (3) semi-supervised learning of environmental models for enhanced survey and search mission effectiveness. Specific capabilities our group has demonstrated include selective data delivery via acoustic link; near real-time reprogramming of vehicle mission programs during otherwise preplanned dives; and validation of autonomous decision-making processes with human-supervision. These elements have been recently demonstrated

  12. Bio-Inspired Pressure Sensing for Active Yaw Control of Underwater Vehicles

    NASA Astrophysics Data System (ADS)

    Gao, Amy; Triantafyllou, Michael

    2012-11-01

    A towed underwater vehicle equipped with a bio-inspired artificial lateral line was constructed and tested with the goal of active detection and correction of the vehicle's angle of attack. Preliminary experiments demonstrate that a low number of sensors are sufficient to enable the discrimination between different orientations, and that a basic proportional controller is capable of keeping the vehicle aligned with the direction of flow. We propose that a model based controller could be developed to improve system response. Toward this, we derive a vehicle model based on a first-order 3D Rankine Source Panel Method, which is shown to be competent in estimating the pressure field in the region of interest during motion at constant angles of attack, and during execution of dynamic maneuvers. To solve the inverse problem of estimating the vehicle orientation given specific pressure measurements, an Unscented Kalman Filter is developed around the model. It is shown to provide a close estimation of the vehicle state using experimentally collected pressure measurements. This demonstrates that an artificial lateral line is a promising technology for dynamically mediating the angle of a body relative to the oncoming flow.

  13. MEMS sensors for assessing flow-related control of an underwater biomimetic robotic stingray.

    PubMed

    Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Haghighi, Reza; Cloitre, Audren; Alvarado, Pablo Valdivia Y; Miao, Jianmin; Triantafyllou, Michael

    2015-05-18

    A major difference between manmade underwater robotic vehicles (URVs) and undersea animals is the dense arrays of sensors on the body of the latter which enable them to execute extreme control of their limbs and demonstrate super-maneuverability. There is a high demand for miniaturized, low-powered, lightweight and robust sensors that can perform sensing on URVs to improve their control and maneuverability. In this paper, we present the design, fabrication and experimental testing of two types of microelectromechanical systems (MEMS) sensors that benefit the situational awareness and control of a robotic stingray. The first one is a piezoresistive liquid crystal polymer haircell flow sensor which is employed to determine the velocity of propagation of the stingray. The second one is Pb(Zr(0.52)Ti(0.48))O3 piezoelectric micro-diaphragm pressure sensor which measures various flapping parameters of the stingray's fins that are key parameters to control the robot locomotion. The polymer flow sensors determine that by increasing the flapping frequency of the fins from 0.5 to 3 Hz the average velocity of the stingray increases from 0.05 to 0.4 BL s(-1), respectively. The role of these sensors in detecting errors in control and functioning of the actuators in performing tasks like flapping at a desired amplitude and frequency, swimming at a desired velocity and direction are quantified. The proposed sensors are also used to provide inputs for a model predictive control which allows the robot to track a desired trajectory. Although a robotic stingray is used as a platform to emphasize the role of the MEMS sensors, the applications can be extended to most URVs.

  14. Google™ underwater

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-10-01

    The first underwater panoramic images were added to Google Maps™, the company announced on 25 September. This first “underwater Street View collection,” launched in partnership with the Caitlin Seaview Survey, provides people with the opportunity to “become the next virtual Jacques Cousteau.” For more information, see: maps.google.com/ocean.

  15. Physiological responses to repeated apneas in underwater hockey players and controls.

    PubMed

    Lemaître, F; Polin, D; Joulia, F; Boutry, A; Le Pessot, D; Chollet, D; Tourny-Chollet, C

    2007-01-01

    The aim of this study was to investigate the effects of short repeated apneas on breathing pattern and circulatory response in trained (underwater hockey players: UHP) and untrained (controls: CTL) subjects. The subjects performed five apneas (A1-A5) while cycling with the face immersed in thermoneutral water. Respiratory parameters were recorded 1 minute before and after each apnea and venous blood samples were collected before each apnea and at 0, 2, 5 and 10 minutes after the last apnea. Arterial saturation (SaO2) and heart rate were continuously recorded during the experiment. Before the repeated apneas, UHP had lower ventilation, higher P(ET)CO2 (p < 0.05) and lower P(ET)O2 than CTL (p < 0.001). After the apneas, the P(ET)O2 values were always lower in UHP (p < 0.001) than CTL but with no difference for averaged P(ET)CO2 (p = 0.32). The apnea response, i.e., bradycardia and increased mean arterial blood pressure, was observed and it remained unchanged throughout the series in the two groups. The SaO, decreased in both groups during each apnea but the post-exercise SaO2 values were higher in UHP after A2 to A5 than in CTL (p < 0.01). The post-apnea lactate concentrations were lower in UHP than in CTL. These results indicate that more pronounced bradycardia could lead to less oxygen desaturation during repeated apneas in UHP. The UHP show a specific hypoventilatory pattern after repeated apneas, as well as a more pronounced cardiovascular response than CTL. They indeed showed no detraining of the diving response.

  16. Vision Underwater.

    ERIC Educational Resources Information Center

    Levine, Joseph S.

    1980-01-01

    Provides information regarding underwater vision. Includes a discussion of optically important interfaces, increased eye size of organisms at greater depths, visual peculiarities regarding the habitat of the coastal environment, and various pigment visual systems. (CS)

  17. An acoustically controlled tetherless underwater vehicle for installation and maintenance of neutrino detectors in the deep ocean

    SciTech Connect

    Ballou, Philip J.

    1997-02-01

    The task of installing and servicing high energy neutrino detectors in the deep ocean from a surface support vessel is problematic using conventional tethered systems. An array of multiple detector strings rising 500 m from the ocean floor, and forming a grid with 50 m spacing between the strings, presents a substantial entanglement hazard for equipment cables deployed from the surface. Such tasks may be accomplished with fewer risks using a tetherless underwater remotely operated vehicle that has a local acoustic telemetry link to send control commands and sensor data between the vehicle and a stationary hydrophone suspended above or just outside the perimeter of the work site. The Phase I effort involves the development of an underwater acoustic telemetry link for vehicle control and sensor feedback, the evaluation of video compression methods for real-time acoustic transmission of video through the water, and the defining of local control routines on board the vehicle to allow it to perform certain basic maneuvering tasks autonomously, or to initiate a self-rescue if the acoustic control link should be lost. In Phase II, a prototype tetherless vehicle system will be designed and constructed to demonstrate the ability to install cable interconnections within a detector array at 4 km depth. The same control technology could be used with a larger more powerful vehicle to maneuver the detector strings into desired positions as they are being lowered to the ocean floor.

  18. Semi-active control of piezoelectric coating's underwater sound absorption by combining design of the shunt impedances

    NASA Astrophysics Data System (ADS)

    Sun, Yang; Li, Zhaohui; Huang, Aigen; Li, Qihu

    2015-10-01

    Piezoelectric shunt damping technology has been applied in the field of underwater sound absorption in recent years. In order to achieve broadband echo reduction, semi-active control of sound absorption of multi-layered piezoelectric coating by shunt damping is significant. In this paper, a practical method is proposed to control the underwater sound absorption coefficients of piezoelectric coating layers by combining design of the shunt impedance that allows certain sound absorption coefficients at setting frequencies. A one-dimensional electro-acoustic model of the piezoelectric coating and the backing is established based on the Mason equivalent circuit theory. First, the shunt impedance of the coating is derived under the constraint of sound absorption coefficient at one frequency. Then, taking the 1-3 piezoelectric composite coating as an example, the sound absorption properties of the coating shunted to the designed shunt impedance are investigated. Next, on the basis of that, an iterative method for two constrained frequencies and an optimizing algorithm for multiple constrained frequencies are provided for combining design of the shunt impedances. At last, an experimental sample with four piezoelectric material layers is manufactured, of which the sound absorption coefficients are measured in an impedance tube. The experimental results show good agreement with the finite element simulation results. It is proved that a serial R-L circuit can control the peak frequency, maximum and bandwidth of the sound absorption coefficient and the combining R-L circuits shunted to multiple layers can control the sound absorption coefficients at multiple frequencies.

  19. Underwater Transparent Miniature "Mechanical Hand" Based on Femtosecond Laser-Induced Controllable Oil-Adhesive Patterned Glass for Oil Droplet Manipulation.

    PubMed

    Huo, Jinglan; Yang, Qing; Chen, Feng; Yong, Jiale; Fang, Yao; Zhang, Jingzhou; Liu, Lin; Hou, Xun

    2017-04-03

    Development of underwater superoleophobic surfaces has captured the imagination of researchers because of their applications; especially, oil manipulation based on such surfaces has attracted much attention. Here, we show a simple and effective way to fabricate an underwater transparent miniature "mechanical hand" based on controllable oil-adhesive patterned glass using a femtosecond laser. The underwater oil-adhesive force of the patterned glasses that compose the "mechanical hand" device can be controlled from ultralow to ultrahigh by adjusting the ratio of the untreated flat glass area to the laser-ablated rough area. These surfaces also showed favorable transparency in water. Various oils such as chloroform, hexadecane, n-dodecane, decane, liquid paraffin, and petroleum ether were tested, and their repellency against the as-prepared surfaces in water medium was confirmed. Moreover, the "mechanical hand" was used to implement oil transportation, fusion, and rapid capture, which can be applied in the construction of microfluidic devices, in situ detectors, and bioreactors.

  20. Abiotic control of underwater light in a drinking water reservoir: Photon budget analysis and implications for water quality monitoring

    NASA Astrophysics Data System (ADS)

    Watanabe, Shohei; Laurion, Isabelle; Markager, Stiig; Vincent, Warwick F.

    2015-08-01

    In optically complex inland waters, the underwater attenuation of photosynthetically active radiation (PAR) is controlled by a variable combination of absorption and scattering components of the lake or river water. Here we applied a photon budget approach to identify the main optical components affecting PAR attenuation in Lake St. Charles, a drinking water reservoir for Québec City, Canada. This analysis showed the dominant role of colored dissolved organic matter (CDOM) absorption (average of 44% of total absorption during the sampling period), but with large changes over depth in the absolute and relative contribution of the individual absorption components (water, nonalgal particulates, phytoplankton and CDOM) to PAR attenuation. This pronounced vertical variation occurred because of the large spectral changes in the light field with depth, and it strongly affected the average in situ diffuse absorption coefficients in the water column. For example, the diffuse absorption coefficient for pure-water in the ambient light field was 10-fold higher than the value previously measured in the blue open ocean and erroneously applied to lakes and coastal waters. Photon absorption budget calculations for a range of limnological conditions confirmed that phytoplankton had little direct influence on underwater light, even at chlorophyll a values above those observed during harmful algal blooms in the lake. These results imply that traditional measures of water quality such as Secchi depth and radiometric transparency do not provide a meaningful estimate of the biological state of the water column in CDOM-colored lakes and reservoirs.

  1. Underwater Rays

    ERIC Educational Resources Information Center

    Cepic, Mojca

    2008-01-01

    Light beams in wavy unclear water, also called underwater rays, and caustic networks of light formed at the bottom of shallow water are two faces of a single phenomenon. Derivation of the caustic using only simple geometry, Snell's law and simple derivatives accounts for observations such as the existence of the caustic network on vertical walls,…

  2. Distributed flow estimation and closed-loop control of an underwater vehicle with a multi-modal artificial lateral line.

    PubMed

    DeVries, Levi; Lagor, Francis D; Lei, Hong; Tan, Xiaobo; Paley, Derek A

    2015-03-25

    Bio-inspired sensing modalities enhance the ability of autonomous vehicles to characterize and respond to their environment. This paper concerns the lateral line of cartilaginous and bony fish, which is sensitive to fluid motion and allows fish to sense oncoming flow and the presence of walls or obstacles. The lateral line consists of two types of sensing modalities: canal neuromasts measure approximate pressure gradients, whereas superficial neuromasts measure local flow velocities. By employing an artificial lateral line, the performance of underwater sensing and navigation strategies is improved in dark, cluttered, or murky environments where traditional sensing modalities may be hindered. This paper presents estimation and control strategies enabling an airfoil-shaped unmanned underwater vehicle to assimilate measurements from a bio-inspired, multi-modal artificial lateral line and estimate flow properties for feedback control. We utilize potential flow theory to model the fluid flow past a foil in a uniform flow and in the presence of an upstream obstacle. We derive theoretically justified nonlinear estimation strategies to estimate the free stream flowspeed, angle of attack, and the relative position of an upstream obstacle. The feedback control strategy uses the estimated flow properties to execute bio-inspired behaviors including rheotaxis (the tendency of fish to orient upstream) and station-holding (the tendency of fish to position behind an upstream obstacle). A robotic prototype outfitted with a multi-modal artificial lateral line composed of ionic polymer metal composite and embedded pressure sensors experimentally demonstrates the distributed flow sensing and closed-loop control strategies.

  3. The effect of traveling wave shapes in the maneuver control and efficiency of an underwater robot propelled by an undulating fin

    NASA Astrophysics Data System (ADS)

    Liu, Hanlin; Curet, Oscar

    2016-11-01

    Effective control of propulsive undulating fins has the potential to enhance the maneuverability and efficiency of underwater vehicles allowing them to navigate in more complex environments. Aquatic animals using this type of propulsion are able to perform complex maneuvers by sending different traveling waves along one or multiple elongated fins. Recent work has investigated the propulsive forces, the hydrodynamics and the efficiency of an undulating ribbon fin. However, it is still not understood how different traveling wave shapes along the fin can be used to control the hydrodynamic forces and torques to perform different maneuvers. In this work, we study the effect of traveling wave shapes on the hydrodynamic forces and torques, swimming speed, maneuver control and propulsive performance of an underwater vehicle propelled by an undulating fin. The underwater robot propels by actuating a fin that is composed of sixteen independent rays interconnected with a flexible membrane. The hull contains all the electronics, batteries, motors and sensors. The underwater vehicle was tested in a water tank-flume facility. In a series of experiments, we measured the motion of the vessel and the power consumption for different traveling wave patterns. In addition, we measured the flow around the fin using Particle Image Velocimetry. We present the results concerning the power distribution along the fin, propulsive efficiency, free-swimming speed and pitch control based on different fin kinematics. National Science Foundation under Grant No. 1420774.

  4. Locomotor expertise predicts infants' perseverative errors.

    PubMed

    Berger, Sarah E

    2010-03-01

    This research examined the development of inhibition in a locomotor context. In a within-subjects design, infants received high- and low-demand locomotor A-not-B tasks. In Experiment 1, walking 13-month-old infants followed an indirect path to a goal. In a control condition, infants took a direct route. In Experiment 2, crawling and walking 13-month-old infants crawled through a tunnel to reach a goal at the other end and received the same control condition as in Experiment 1. In both experiments, perseverative errors occurred more often in the high-demand condition than in the low-demand condition. Moreover, in Experiment 2, walkers perseverated more than crawlers, and extent of perseveration was related to infants' locomotor experience. In Experiment 3, the authors addressed a possible confound in Experiment 2 between locomotor expertise and locomotor posture. Novice crawlers perseverated in the difficult tunnels condition, behaving more like novice walkers than expert crawlers. As predicted by a cognitive capacity account of infant perseveration, overtaxed attentional resources resulted in a cognition-action trade-off. Experts who found the task less motorically effortful than novices had more cognitive resources available for problem solving.

  5. Unmanned Surface and Underwater Vehicles

    DTIC Science & Technology

    2007-07-03

    configured for a wide range of research, surveying or monitoring tasks. On the 9th of september 2005, following an accident just outside Reykjavik, Gavia...crew from a Russian submarine in June 2005, see http://english.pravda.ru/ accidents /21/97/384/1593 1_minisub.htn-d) Classification: Location: Underwater...english.pravda.ru/ accidents /21/97/384/1593 1_minisub.html) Classification: Location: Underwater. Control: Remotely Operated. Function: Rescue. Table 30

  6. Locomotor Behaviour of Blattella germanica Modified by DEET

    PubMed Central

    Sfara, Valeria; Mougabure-Cueto, Gastón A.; Zerba, Eduardo N.; Alzogaray, Raúl A.

    2013-01-01

    N,N-diethyl-3-methylbenzamide (DEET) is the active principle of most insect repellents used worldwide. However, its toxicity on insects has not been widely studied. The aim of this work is to study the effects of DEET on the locomotor activity of Blattella germanica. DEET has a dose-dependent repellent activity on B. germanica. Locomotor activity was significantly lower when insects were pre-exposed to 700 µg/cm2 of DEET for 20 or 30 minutes, but it did not change when pre-exposure was shorter. Locomotor activity of insects that were pre-exposed to 2.000 µg/cm2 of DEET for 10 minutes was significantly lower than the movement registered in controls. No differences were observed when insects were pre-exposed to lower concentrations of DEET. A 30-minute pre-exposure to 700 µg/cm2 of DEET caused a significant decrease in locomotor activity. Movement was totally recovered 24 h later. The locomotor activity measured during the exposure to different concentrations of DEET remained unchanged. Insects with decreased locomotor activity were repelled to the same extent than control insects by the same concentration of DEET. We demonstrated that the repellency and modification of locomotor activity elicited by DEET are non-associated phenomena. We also suggested that the reduction in locomotor activity indicates toxicity of DEET, probably to insect nervous system. PMID:24376701

  7. Locomotor behaviour of Blattella germanica modified by DEET.

    PubMed

    Sfara, Valeria; Mougabure-Cueto, Gastón A; Zerba, Eduardo N; Alzogaray, Raúl A

    2013-01-01

    N,N-diethyl-3-methylbenzamide (DEET) is the active principle of most insect repellents used worldwide. However, its toxicity on insects has not been widely studied. The aim of this work is to study the effects of DEET on the locomotor activity of Blattella germanica. DEET has a dose-dependent repellent activity on B. germanica. Locomotor activity was significantly lower when insects were pre-exposed to 700 µg/cm(2) of DEET for 20 or 30 minutes, but it did not change when pre-exposure was shorter. Locomotor activity of insects that were pre-exposed to 2.000 µg/cm(2) of DEET for 10 minutes was significantly lower than the movement registered in controls. No differences were observed when insects were pre-exposed to lower concentrations of DEET. A 30-minute pre-exposure to 700 µg/cm(2) of DEET caused a significant decrease in locomotor activity. Movement was totally recovered 24 h later. The locomotor activity measured during the exposure to different concentrations of DEET remained unchanged. Insects with decreased locomotor activity were repelled to the same extent than control insects by the same concentration of DEET. We demonstrated that the repellency and modification of locomotor activity elicited by DEET are non-associated phenomena. We also suggested that the reduction in locomotor activity indicates toxicity of DEET, probably to insect nervous system.

  8. Underwater optical wireless communication network

    NASA Astrophysics Data System (ADS)

    Arnon, Shlomi

    2010-01-01

    The growing need for underwater observation and subsea monitoring systems has stimulated considerable interest in advancing the enabling technologies of underwater wireless communication and underwater sensor networks. This communication technology is expected to play an important role in investigating climate change, in monitoring biological, biogeochemical, evolutionary, and ecological changes in the sea, ocean, and lake environments, and in helping to control and maintain oil production facilities and harbors using unmanned underwater vehicles (UUVs), submarines, ships, buoys, and divers. However, the present technology of underwater acoustic communication cannot provide the high data rate required to investigate and monitor these environments and facilities. Optical wireless communication has been proposed as the best alternative to meet this challenge. Models are presented for three kinds of optical wireless communication links: (a) a line-of-sight link, (b) a modulating retroreflector link, and (c) a reflective link, all of which can provide the required data rate. We analyze the link performance based on these models. From the analysis, it is clear that as the water absorption increases, the communication performance decreases dramatically for the three link types. However, by using the scattered light it was possible to mitigate this decrease in some cases. It is concluded from the analysis that a high-data-rate underwater optical wireless network is a feasible solution for emerging applications such as UUV-to-UUV links and networks of sensors, and extended ranges in these applications could be achieved by applying a multi-hop concept.

  9. GE underwater test facility studies in zero G simulation

    NASA Technical Reports Server (NTRS)

    Fry, R. H.

    1972-01-01

    The underwater test facility (UTF) is described as an indoor controlled environment test facility designed specifically for zero G simulation, hydrospace manned and unmanned equipment development, and personnel training for both space and underwater exploration. Programs conducted in the UTF include: human engineering criteria for maintenance and repairs of space stations, astronaut performance, helmet distortion, underwater telemetry, and blood transfusion.

  10. Natural Underwater Adhesives.

    PubMed

    Stewart, Russell J; Ransom, Todd C; Hlady, Vladimir

    2011-06-01

    The general topic of this review is protein-based underwater adhesives produced by aquatic organisms. The focus is on mechanisms of interfacial adhesion to native surfaces and controlled underwater solidification of natural water-borne adhesives. Four genera that exemplify the broad range of function, general mechanistic features, and unique adaptations are discussed in detail: blue mussels, acorn barnacles, sandcastle worms, and freshwater caddisfly larva. Aquatic surfaces in nature are charged and in equilibrium with their environment, populated by an electrical double layer of ions as well as adsorbed natural polyelectrolytes and microbial biofilms. Surface adsorption of underwater bioadhesives likely occurs by exchange of surface bound ligands by amino acid sidechains, driven primarily by relative affinities and effective concentrations of polymeric functional groups. Most aquatic organisms exploit modified amino acid sidechains, in particular phosphorylated serines and hydroxylated tyrosines (dopa), with high-surface affinity that form coordinative surface complexes. After delivery to the surfaces as a fluid, permanent natural adhesives solidify to bear sustained loads. Mussel plaques are assembled in a manner superficially reminiscent of in vitro layer-by-layer strategies, with sequentially delivered layers associated through Fe(dopa)(3) coordination bonds. The adhesives of sandcastle worms, caddisfly larva, and barnacles may be delivered in a form somewhat similar to in vitro complex coacervation. Marine adhesives are secreted, or excreted, into seawater that has a significantly higher pH and ionic strength than the internal environment. Empirical evidence suggests these environment triggers could provide minimalistic, fail-safe timing mechanisms to prevent premature solidification (insolubilization) of the glue within the secretory system, yet allow rapid solidification after secretion. Underwater bioadhesives are further strengthened by secondary covalent

  11. Natural Underwater Adhesives

    PubMed Central

    Stewart, Russell J.; Ransom, Todd C.; Hlady, Vladimir

    2011-01-01

    The general topic of this review is protein-based underwater adhesives produced by aquatic organisms. The focus is on mechanisms of interfacial adhesion to native surfaces and controlled underwater solidification of natural water-borne adhesives. Four genera that exemplify the broad range of function, general mechanistic features, and unique adaptations are discussed in detail: blue mussels, acorn barnacles, sandcastle worms, and freshwater caddisfly larva. Aquatic surfaces in nature are charged and in equilibrium with their environment, populated by an electrical double layer of ions as well as adsorbed natural polyelectrolytes and microbial biofilms. Surface adsorption of underwater bioadhesives likely occurs by exchange of surface bound ligands by amino acid sidechains, driven primarily by relative affinities and effective concentrations of polymeric functional groups. Most aquatic organisms exploit modified amino acid sidechains, in particular phosphorylated serines and hydroxylated tyrosines (dopa), with high-surface affinity that form coordinative surface complexes. After delivery to the surfaces as a fluid, permanent natural adhesives solidify to bear sustained loads. Mussel plaques are assembled in a manner superficially reminiscent of in vitro layer-by-layer strategies, with sequentially delivered layers associated through Fe(dopa)3 coordination bonds. The adhesives of sandcastle worms, caddisfly larva, and barnacles may be delivered in a form somewhat similar to in vitro complex coacervation. Marine adhesives are secreted, or excreted, into seawater that has a significantly higher pH and ionic strength than the internal environment. Empirical evidence suggests these environment triggers could provide minimalistic, fail-safe timing mechanisms to prevent premature solidification (insolubilization) of the glue within the secretory system, yet allow rapid solidification after secretion. Underwater bioadhesives are further strengthened by secondary covalent

  12. Mode-dependent control of human walking and running as revealed by split-belt locomotor adaptation.

    PubMed

    Ogawa, Tetsuya; Kawashima, Noritaka; Obata, Hiroki; Kanosue, Kazuyuki; Nakazawa, Kimitaka

    2015-10-01

    Here, we investigate the association of neural control between walking and running, and in particular, how these two gait modes at different velocities are controlled by the central nervous system. The subjects were fully adapted by acquiring modified motor patterns to either walk or run on a split-belt treadmill driven in split mode (asymmetry in the velocities of two belts at 1.0 and 2.0 m s(-1)). Subsequently, we tested how the adaptation affected walking and running at three different velocities in the tied mode (equal belt velocities). At 0.75 m s(-1), we found a preference to walk, at 1.50 m s(-1), there was a preference to both walk and run, and at a velocity of 2.25 m s(-1) there was a preference to run. Both walking and running on the split belt resulted in the emergence of a significant aftereffect (asymmetrical movement) at all of the velocities tested when walking after adapting to walk and running after adapting to run. However, for contrasting modes (i.e. running after adapting to walk and walking after adapting to run), such aftereffects were far less evident at all velocities; thus showing only limited transfer across gait modes. The results demonstrate a clear mode dependency in the neural control of human walking and running. In addition, only for walking, was there a degree of velocity dependency.

  13. Chronic electrical stimulation of the intact corticospinal system after unilateral injury restores skilled locomotor control and promotes spinal axon outgrowth.

    PubMed

    Carmel, Jason B; Berrol, Lauren J; Brus-Ramer, Marcel; Martin, John H

    2010-08-11

    Injury to the brain or spinal cord usually preserves some corticospinal (CS) connections. These residual circuits sprout spontaneously and in response to activity-based treatments. We hypothesized that augmenting activity in spared CS circuits would restore the skilled motor control lost after injury and augment outgrowth of CS terminations in the spinal cord. After selective injury of one half of the CS tract (CST) in the rat, we applied 10 d of electrical stimulation to the forelimb area of motor cortex of the spared half and tested motor performance for 30 d. Rats with injury and CST stimulation showed substantial improvements in skilled paw placement while walking over a horizontal ladder. By the end of the testing period, the walking errors of the previously impaired forelimb in rats with injury and stimulation returned to baseline, while the errors remained elevated in rats with injury only. Whereas the time to perform the task returned to normal in all animals, the pattern of errors returned to normal only in the stimulated group. Electrical stimulation also caused robust outgrowth of CST axon terminations in the ipsilateral spinal cord, the side of impairment, compared with rats with injury only. The outgrowth was directed to the normal gray matter territory of ipsilateral CST axon terminations. Thus, stimulation of spared CS circuits induced substantial axon outgrowth to the largely denervated side of the spinal cord and restored normal motor control in the previously impaired limbs.

  14. Underwater Sensor Nodes and Networks

    PubMed Central

    Lloret, Jaime

    2013-01-01

    Sensor technology has matured enough to be used in any type of environment. The appearance of new physical sensors has increased the range of environmental parameters for gathering data. Because of the huge amount of unexploited resources in the ocean environment, there is a need of new research in the field of sensors and sensor networks. This special issue is focused on collecting recent advances on underwater sensors and underwater sensor networks in order to measure, monitor, surveillance of and control of underwater environments. On the one hand, from the sensor node perspective, we will see works related with the deployment of physical sensors, development of sensor nodes and transceivers for sensor nodes, sensor measurement analysis and several issues such as layer 1 and 2 protocols for underwater communication and sensor localization and positioning systems. On the other hand, from the sensor network perspective, we will see several architectures and protocols for underwater environments and analysis concerning sensor network measurements. Both sides will provide us a complete view of last scientific advances in this research field. PMID:24013489

  15. AURP: An AUV-Aided Underwater Routing Protocol for Underwater Acoustic Sensor Networks

    PubMed Central

    Yoon, Seokhoon; Azad, Abul K.; Oh, Hoon; Kim, Sunghwan

    2012-01-01

    Deploying a multi-hop underwater acoustic sensor network (UASN) in a large area brings about new challenges in reliable data transmissions and survivability of network due to the limited underwater communication range/bandwidth and the limited energy of underwater sensor nodes. In order to address those challenges and achieve the objectives of maximization of data delivery ratio and minimization of energy consumption of underwater sensor nodes, this paper proposes a new underwater routing scheme, namely AURP (AUV-aided underwater routing protocol), which uses not only heterogeneous acoustic communication channels but also controlled mobility of multiple autonomous underwater vehicles (AUVs). In AURP, the total data transmissions are minimized by using AUVs as relay nodes, which collect sensed data from gateway nodes and then forward to the sink. Moreover, controlled mobility of AUVs makes it possible to apply a short-range high data rate underwater channel for transmissions of a large amount of data. To the best to our knowledge, this work is the first attempt to employ multiple AUVs as relay nodes in a multi-hop UASN to improve the network performance in terms of data delivery ratio and energy consumption. Simulations, which are incorporated with a realistic underwater acoustic communication channel model, are carried out to evaluate the performance of the proposed scheme, and the results indicate that a high delivery ratio and low energy consumption can be achieved. PMID:22438740

  16. Underwater lab

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    The University of Southern California's Catalina Marine Science Center (CMSC) has announced plans to build an underwater marine research laboratory near Santa Catalina Island off the California coast. The project, which will take 2 years to build, will be sponsored by the National Oceanic and Atmospheric Administration (NOAA). The laboratory will be similar in concept to the U.S. Navy Sea Lab III, which was canceled some time ago.The project's purpose is to give divers access to a laboratory without having to surface. The project leader, Andrew Pilmanis, of the University of Southern California, stated recently (Industrial Research and Development, July 1983): “By the nature of the work, scientists require a lot of bottom time, and to do it by scuba isn't practical…. The only way to do that is with saturation diving. Once the diver is saturated with inert gas, whether the individual stays a few days or for months, only one decompression is required.” Divers will typically stay in the laboratory for 7-10 days. The laboratory will initially be placed at a depth of 20 m, later to be refloated and located at depths to 37 m.

  17. Fabrication of Slippery Lubricant-Infused Porous Surface with High Underwater Transparency for the Control of Marine Biofouling.

    PubMed

    Wang, Peng; Zhang, Dun; Sun, Shimei; Li, Tianping; Sun, Yan

    2017-01-11

    Marine optical instruments are bearing serious biofouling problem, which affects the accuracy of data collected. To solve the biofouling problem of marine optical instruments, a novel instance of slippery lubricant-infused porous surface (SLIPS) with high underwater-transparency was designed over glass substrate via infusing lubricant into its porous microstructure fabricated with hydrothermal method. The advantage of SLIPS as antibiofouling strategy to marine optical instruments was proven by comparing its underwater optical and antibiofouling performances with three kinds of samples (hydrophilic glass sample, textured hydrophilic glass sample, and superhydrophobic glass sample). The modification of SLIPS enhances the underwater-transparency of glass sample within the wavelength of 500-800 nm, for the infusion of lubricant with lower refractive index than glass substrate. In contrast with hydrophilic surface, textured hydrophilic surface and superhydrophobic surface, SLIPS can significantly inhibit bacterial and algal settlements, thereby maintaining high underwater-transparency in both dynamic and static seawater. The inhibition of bacterial and algal settlements over SLIPS results from its liquid-like property. The contact angle hysteresis of water over SLIPS increases with immersion time in seawater under different conditions (static, dynamic, and vibration conditions). Both dynamic and vibration conditions accelerate the failure of SLIPS exposed in seawater. This research provides valuable information for solving biofouling problem of marine optical instruments with SLIPS.

  18. A Controlled Laboratory Environment to Study EO Signal Degradation Due to Underwater Turbulence

    DTIC Science & Technology

    2015-05-11

    to examine and mitigate turbulence effects, we set up a laboratory turbulence environment allowing the variation of turbulence intensity. Convective ...profilers and fast thermistor probes. The turbulence measurements are complemented by computational fluid dynamics simulations of convective turbulence...outfitted with stainless steel plates at the bottom and top that can be temperature controlled (Fig. 1, left). In this tank, convective Rayleigh

  19. Reliability review of the remote tool delivery system locomotor

    SciTech Connect

    Chesser, J.B.

    1999-04-01

    The locomotor being built by RedZone Robotics is designed to serve as a remote tool delivery (RID) system for waste retrieval, tank cleaning, viewing, and inspection inside the high-level waste tanks 8D-1 and 8D-2 at West Valley Nuclear Services (WVNS). The RTD systm is to be deployed through a tank riser. The locomotor portion of the RTD system is designed to be inserted into the tank and is to be capable of moving around the tank by supporting itself and moving on the tank internal structural columns. The locomotor will serve as a mounting platform for a dexterous manipulator arm. The complete RTD system consists of the locomotor, dexterous manipulator arm, cameras, lights, cables, hoses, cable/hose management system, power supply, and operator control station.

  20. A Microcomputer-Based Controller for an Autonomous Underwater Vehicle (AUV)

    DTIC Science & Technology

    1990-03-01

    possible dynamic situations. In the case of the AUV, a model based on the United States Navy’s Swimmer Delivery Vehicle is used. This model is...mul(Matrix MI, int rl, int cl, Matrix M2, imt r2, int c2, Matrix M3); void control8( double *mstate, double *inputs, double ordereddepth, double...12 states depicted in Table 2. of this thesis using the dynamic equations of motion modeled after the U.S. Navy’s Swimmer Delivery Vehicle. The

  1. Locomotor adaptations of some gelatinous zooplankton.

    PubMed

    Bone, Q

    1985-01-01

    Swimming behaviour and locomotor adaptations are described in chaetognaths, larvacean tunicates, some cnidaria, and thaliacean tunicates. The first two groups swim by oscillating a flattened tail, the others by jet propulsion. In chaetognaths, the locomotor muscle fibres are extensively coupled and relatively sparsely innervated, they exhibit compound spike-like potentials. The motoneurons controlling the rhythmic activity of the locomotor muscle lie in a ventral ganglion whose organization is briefly described. Rhythmic swimming bursts in larvaceans are similarly driven by a caudal ganglion near the base of the tail, but each caudal muscle cell is separately innervated by two sets of motor nerves, as well as being coupled to its neighbours. The external epithelium is excitable, and linked to the caudal ganglion by the axons of central cells. Mechanical stimulation of the epithelium evokes receptor potentials followed by action potentials and by bursts of rapid swimming. The trachyline medusa Aglantha and the small siphonophore Chelophyes also show rapid escape responses; in Aglantha these are driven by a specialized giant axon system lacking in other hydromedusae, and in Chelophyes. Slow swimming in Aglantha apparently involves a second nerve supply to the same muscle sheets used in rapid swimming, whereas in Chelophyes slow swimming results from the activity of the smaller posterior nectophore. Slow swimming in siphonophores is more economical than the rapid responses. In the hydrozoan medusa Polyorchis (as in Chelophyes) action potentials in the locomotor muscle sheet change in shape during swimming bursts, and their duration is related to the size of the medusa; they are not simply triggers of muscular contraction. The two groups of thaliacean tunicates are specialized differently. Doliolum is adapted for single rapid jet pulses (during which it achieves instantaneous velocities of 50 body lengths s-l), whilst salps are adapted for slow continuous swimming. The

  2. Underwater hearing: A review

    NASA Astrophysics Data System (ADS)

    Al-Masri, M.; Martin, A.; Nedwell, J.

    1993-05-01

    In view of the prevalence of hearing loss among commercial divers and the absence of widely accepted noise exposure limits for occupational underwater use, a review of studies of underwater hearing thresholds and hearing mechanisms was undertaken with the ultimate aim of developing noise exposure limits. Previous studies of underwater hearing thresholds appear to show that the ear underwater is less sensitive than compared with air. However, a surprisingly wide range of values for underwater hearing thresholds was reported, for example 35-90 dB SPL(re 20 MuPa) at 0.25 kHz and 30-80 dB at 1 kHz. No representative single threshold curve can be extracted with any validity. Possible reasons for such a wide scatter of results include high underwater ambient noise levels which may have masked the subjects underwater hearing thresholds, ill defined stimuli and underwater sound fields, and variable and informal audiometric methodology. Previous authors have proposed three somewhat interlinked theories to explain how sound is transmitted from water to the cochlea. These involve: the 'auricular' conduction pathway, the bone conduction pathway, and the dual conduction pathway. Up to this day, no one pathway has been shown to predominate, and all of them have been poorly evaluated. It is also possible that the presence of air bubbles in the ear canal and increased water depth may have significant effects on underwater hearing thresholds. These effects may be dependent on the underwater hearing mechanism. Again, the studies reviewed give conflicting results and no valid conclusion can be drawn. It is apparent that further experimental studies are required to establish underwater hearing thresholds and to provide an understanding of the mechanisms of hearing underwater. These should be based upon suitable facilities and methodologies for testing hearing thresholds underwater following modern and scientific audio metric practice.

  3. Underwater gait analysis in Parkinson's disease.

    PubMed

    Volpe, Daniele; Pavan, Davide; Morris, Meg; Guiotto, Annamaria; Iansek, Robert; Fortuna, Sofia; Frazzitta, Giuseppe; Sawacha, Zimi

    2017-02-01

    Although hydrotherapy is one of the physical therapies adopted to optimize gait rehabilitation in people with Parkinson disease, the quantitative measurement of gait-related outcomes has not been provided yet. This work aims to document the gait improvements in a group of parkinsonians after a hydrotherapy program through 2D and 3D underwater and on land gait analysis. Thirty-four parkinsonians and twenty-two controls were enrolled, divided into two different cohorts. In the first one, 2 groups of patients underwent underwater or land based walking training; controls underwent underwater walking training. Hence pre-treatment 2D underwater and on land gait analysis were performed, together with post-treatment on land gait analysis. Considering that current literature documented a reduced movement amplitude in parkinsonians across all lower limb joints in all movement planes, 3D underwater and on land gait analysis were performed on a second cohort of subjects (10 parkinsonians and 10 controls) who underwent underwater gait training. Baseline land 2D and 3D gait analysis in parkinsonians showed shorter stride length and slower speed than controls, in agreement with previous findings. Comparison between underwater and on land gait analysis showed reduction in stride length, cadence and speed on both parkinsonians and controls. Although patients who underwent underwater treatment exhibited significant changes on spatiotemporal parameters and sagittal plane lower limb kinematics, 3D gait analysis documented a significant (p<0.05) improvement in all movement planes. These data deserve attention for research directions promoting the optimal recovery and maintenance of walking ability.

  4. Degradation of mouse locomotor pattern in the absence of proprioceptive sensory feedback.

    PubMed

    Akay, Turgay; Tourtellotte, Warren G; Arber, Silvia; Jessell, Thomas M

    2014-11-25

    Mammalian locomotor programs are thought to be directed by the actions of spinal interneuron circuits collectively referred to as "central pattern generators." The contribution of proprioceptive sensory feedback to the coordination of locomotor activity remains less clear. We have analyzed changes in mouse locomotor pattern under conditions in which proprioceptive feedback is attenuated genetically and biomechanically. We find that locomotor pattern degrades upon elimination of proprioceptive feedback from muscle spindles and Golgi tendon organs. The degradation of locomotor pattern is manifest as the loss of interjoint coordination and alternation of flexor and extensor muscles. Group Ia/II sensory feedback from muscle spindles has a predominant influence in patterning the activity of flexor muscles, whereas the redundant activities of group Ia/II and group Ib afferents appear to determine the pattern of extensor muscle firing. These findings establish a role for proprioceptive feedback in the control of fundamental aspects of mammalian locomotor behavior.

  5. Movement Exploration and Locomotor Skills.

    ERIC Educational Resources Information Center

    National Center on Educational Media and Materials for the Handicapped, Columbus, OH.

    Selected from the National Instructional Materials Information System (NIMIS)--a computer based on-line interactive retrieval system on special education materials--the bibliography covers 23 materials for teaching movement exploration and locomotor skills to handicapped students at all educational levels. Entries are presented in order of NIMIS…

  6. Underwater Scene Composition

    ERIC Educational Resources Information Center

    Kim, Nanyoung

    2009-01-01

    In this article, the author describes an underwater scene composition for elementary-education majors. This project deals with watercolor with crayon or oil-pastel resist (medium); the beauty of nature represented by fish in the underwater scene (theme); texture and pattern (design elements); drawing simple forms (drawing skill); and composition…

  7. Colorful Underwater Sea Creatures

    ERIC Educational Resources Information Center

    McCutcheon, Heather

    2011-01-01

    In this article, the author describes a project wherein students created colorful underwater sea creatures. This project began with a discussion about underwater sea creatures and how they live. The first step was making the multi-colored tissue paper that would become sea creatures and seaweed. Once students had the shapes of their sea creatures…

  8. Sex differences in locomotor effects of morphine in the rat

    PubMed Central

    Craft, Rebecca M.; Clark, James L.; Hart, Stephen P.; Pinckney, Megan K.

    2007-01-01

    Sex differences in reinforcing, analgesic and other effects of opioids have been demonstrated; however, the extent to which sex differences in motoric effects of opioids contribute to apparent sex differences in their primary effects is not known. The goal of this study was to compare the effects of the prototypic mu opioid agonist morphine on locomotor activity in male vs. female rats. Saline or morphine (1-10 mg/kg) was administered s.c. to adult Sprague-Dawley rats, which were placed into a photobeam apparatus for 3-5 hr to measure activity. Modulation of morphine's effects by gonadal hormones and by handling (either during the test session or for 4 days before the test session) were examined. Morphine initially suppressed and later increased locomotor activity in both sexes relative to their saline-injected controls, but males were more sensitive than females to the initial locomotor suppressant effect of morphine. Intermittent, brief handling during the 3-hr test session blunted morphine-induced locomotor activation in both sexes. Females in proestrus were the most sensitive to morphine's locomotor-stimulant effect, with females in estrus showing the least response to morphine. Gonadectomized (GDX) males with or without testosterone were equally sensitive to morphine's effects, whereas GDX females treated with estradiol showed a blunted response to morphine's effects, similar to intact females in estrus. Brief handling on each of 4 consecutive days pre-test attenuated morphine's locomotor suppressant effect in males but had no effect in females, thereby eliminating the sex difference. These data suggest that sex differences in morphine's effects on locomotor activity can be attributed to gonadal hormones in females, and to differential stress-induced modulation of morphine's effects in males vs. females. PMID:17217999

  9. Perception--action coupling model for human locomotor pointing.

    PubMed

    de Rugy, A; Taga, G; Montagne, G; Buekers, M J; Laurent, M

    2002-08-01

    How do humans achieve the precise positioning of the feet during walking, for example, to reach the first step of a stairway? We addressed this question at the visuomotor integration level. Based on the optical specification of the required adaptation, a dynamical system model of the visuomotor control of human locomotor pointing was devised for the positioning of a foot on a visible target on the floor during walking. Visuomotor integration consists of directly linking optical information to a motor command that specifically modulates step length in accordance with the ongoing dynamics of locomotor pattern generation. The adaptation of locomotion emerges from a perception-action coupling type of control based on temporal information rather than on feedforward planning of movements. The proposed model reproduces experimental results obtained for human locomotor pointing.

  10. Analysis of recordings from underwater controlled sources in the Pacific Ocean received by the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO)

    NASA Astrophysics Data System (ADS)

    Yamada, Tomoaki; Zampolli, Mario; Haralabus, Georgios; Heaney, Kevin; Prior, Mark; Isse, Takeshi

    2016-04-01

    Controlled impulsive scientific underwater sound sources in the Northwestern Pacific were observed at two IMS hydroacoustic stations in the Pacific Ocean. Although these experiments were conducted with the aim of studying the physical properties of the plate boundaries inside the Earth, they are also suitable for the investigation of long range underwater acoustic detections. In spite of the fact that the energy of these controlled impulsive scientific sources is significantly smaller than that of nuclear explosions, the signals were obtained by IMS hydrophone stations thousands of kilometres away and also by distant ocean bottom instruments operated by various Institutes, such as the Earthquake Research Institute, University of Tokyo. These experiments provide calibrated (yield, time, location) long-range acoustic transmissions, which enable one to examine the physics of long-range acoustic propagation and to verify the capabilities of the CTBTO IMS network to detect even small explosions.The two IMS stations used are H03 (Juan Fernandez Island, Chile) off the coast of Chile in the Southeastern Pacific and H11 (Wake Island, USA) in the Western Pacific. Both stations consist of two triplets of hydrophones in the SOFAR channel, which monitor the oceans for signs of nuclear explosions. H03 detected low-yield explosions above flat terrain at distances of 15,000 km across the Pacific as well as explosions above the landward slope off the coast of Japan at distances above 16,000 km across the Pacific. These records showed that source signatures, such as short duration and bubble pulses, were preserved over the long propagation distances. It was found that the observed maximum amplitudes from each source exhibit order of magnitude variations even when the yield and detonation depth are the same. The experimental data and transmission loss simulations suggest that bathymetric features around the sources and between the sources and the receivers are the main causes for

  11. Strategies of locomotor collision avoidance.

    PubMed

    Basili, Patrizia; Sağlam, Murat; Kruse, Thibault; Huber, Markus; Kirsch, Alexandra; Glasauer, Stefan

    2013-03-01

    Collision avoidance during locomotion can be achieved by a variety of strategies. While in some situations only a single trajectory will successfully avoid impact, in many cases several different strategies are possible. Locomotor experiments in the presence of static boundary conditions have suggested that the choice of an appropriate trajectory is based on a maximum-smoothness strategy. Here we analyzed locomotor trajectories of subjects avoiding collision with another human crossing their path orthogonally. In such a case, changing walking direction while keeping speed or keeping walking direction while changing speed would be two extremes of solving the problem. Our participants clearly favored changing their walking speed while keeping the path on a straight line between start and goal. To interpret this result, we calculated the costs of the chosen trajectories in terms of a smoothness-maximization criterion and simulated the trajectories with a computational model. Data analysis together with model simulation showed that the experimentally chosen trajectory to avoid collision with a moving human is not the optimally smooth solution. However, even though the trajectory is not globally smooth, it was still locally smooth. Modeling further confirmed that, in presence of the moving human, there is always a trajectory that would be smoother but would deviate from the straight line. We therefore conclude that the maximum smoothness strategy previously suggested for static environments no longer holds for locomotor path planning and execution in dynamically changing environments such as the one tested here.

  12. Training Locomotor Networks

    PubMed Central

    Edgerton, V. Reggie; Courtine, Grégoire; Gerasimenko, Yury P.; Lavrov, Igor; Ichiyama, Ronaldo M.; Fong, Andy J.; Cai, Lance L.; Otoshi, Chad K.; Tillakaratne, Niranjala J.K.; Burdick, Joel W.; Roy, Roland R.

    2008-01-01

    For a complete adult spinal rat to regain some weight-bearing stepping capability, it appears that a sequence of specific proprioceptive inputs that are similar, but not identical, from step to step must be generated over repetitive step cycles. Furthermore, these cycles must include the activation of specific neural circuits that are intrinsic to the lumbosacral spinal cord segments. For these sensorimotor pathways to be effective in generating stepping, the spinal circuitry must be modulated to an appropriate excitability level. This level of modulation is sustained from supraspinal input in intact, but not spinal, rats. In a series of experiments with complete spinal rats, we have shown that an appropriate level of excitability of the spinal circuitry can be achieved using widely different means. For example, this modulation level can be acquired pharmacologically, via epidural electrical stimulation over specific lumbosacral spinal cord segments, and/or by use-dependent mechanisms such as step or stand training. Evidence as to how each of these treatments can “tune” the spinal circuitry to a “physiological state” that enables it to respond appropriately to proprioceptive input will be presented. We have found that each of these interventions can enable the proprioceptive input to actually control extensive details that define the dynamics of stepping over a range of speeds, loads, and directions. A series of experiments will be described that illustrate sensory control of stepping and standing after a spinal cord injury and the necessity for the “physiological state” of the spinal circuitry to be modulated within a critical window of excitability for this control to be manifested. The present findings have important consequences not only for our understanding of how the motor pattern for stepping is formed, but also for the design of rehabilitation intervention to restore lumbosacral circuit function in humans following a spinal cord injury. PMID

  13. Advanced Concepts for Underwater Acoustic Channel Modeling

    NASA Astrophysics Data System (ADS)

    Etter, P. C.; Haas, C. H.; Ramani, D. V.

    2014-12-01

    This paper examines nearshore underwater-acoustic channel modeling concepts and compares channel-state information requirements against existing modeling capabilities. This process defines a subset of candidate acoustic models suitable for simulating signal propagation in underwater communications. Underwater-acoustic communications find many practical applications in coastal oceanography, and networking is the enabling technology for these applications. Such networks can be formed by establishing two-way acoustic links between autonomous underwater vehicles and moored oceanographic sensors. These networks can be connected to a surface unit for further data transfer to ships, satellites, or shore stations via a radio-frequency link. This configuration establishes an interactive environment in which researchers can extract real-time data from multiple, but distant, underwater instruments. After evaluating the obtained data, control messages can be sent back to individual instruments to adapt the networks to changing situations. Underwater networks can also be used to increase the operating ranges of autonomous underwater vehicles by hopping the control and data messages through networks that cover large areas. A model of the ocean medium between acoustic sources and receivers is called a channel model. In an oceanic channel, characteristics of the acoustic signals change as they travel from transmitters to receivers. These characteristics depend upon the acoustic frequency, the distances between sources and receivers, the paths followed by the signals, and the prevailing ocean environment in the vicinity of the paths. Properties of the received signals can be derived from those of the transmitted signals using these channel models. This study concludes that ray-theory models are best suited to the simulation of acoustic signal propagation in oceanic channels and identifies 33 such models that are eligible candidates.

  14. Remote repair grinding of cracks underwater

    SciTech Connect

    Thomessen, T.; Lien, T.K.; Johnsen, K.

    1994-12-31

    This paper presents a new approach for remote repair grinding of cracks underwater. The approach uses Controlled Material Removal Rate (CMRR) grinding strategy which is based on a force controlled manipulator for handling the grinding machine. The CMRR-strategy requires an empirical model of the grinding process. Different grinding wheels were tested in underwater grinding, and experiments were carried out to derived an empirical model of the grinding process for a cylindrical grinding wheel. Finally, the CMRR-strategy was applied to grind a groove according to given specifications. The force control system was used to measure the groove geometry after grinding. The results were promising and demonstrate clearly that the CMRR-strategy is very useful in underwater grinding due to its high flexibility.

  15. Underwater hydrophone location survey

    NASA Technical Reports Server (NTRS)

    Cecil, Jack B.

    1993-01-01

    The Atlantic Undersea Test and Evaluation Center (AUTEC) is a U.S. Navy test range located on Andros Island, Bahamas, and a Division of the Naval Undersea Warfare Center (NUWC), Newport, RI. The Headquarters of AUTEC is located at a facility in West Palm Beach, FL. AUTEC's primary mission is to provide the U.S. Navy with a deep-water test and evaluation facility for making underwater acoustic measurements, testing and calibrating sonars, and providing accurate underwater, surface, and in-air tracking data on surface ships, submarines, aircraft, and weapon systems. Many of these programs are in support of Antisubmarine Warfare (ASW), undersea research and development programs, and Fleet assessment and operational readiness trials. Most tests conducted at AUTEC require precise underwater tracking (plus or minus 3 yards) of multiple acoustic signals emitted with the correct waveshape and repetition criteria from either a surface craft or underwater vehicle.

  16. Smelling and Tasting Underwater.

    ERIC Educational Resources Information Center

    Atema, Jelle

    1980-01-01

    Discusses differences between smell and taste, comparing these senses in organisms in aquatic and terrestrial environments. Describes the chemical environment underwater and in air, differences in chemoreceptors to receive stimuli, and the organs, brain, and behavior involved in chemoreception. (CS)

  17. Nitric oxide-mediated modulation of the murine locomotor network.

    PubMed

    Foster, Joshua D; Dunford, Catherine; Sillar, Keith T; Miles, Gareth B

    2014-02-01

    Spinal motor control networks are regulated by neuromodulatory systems to allow adaptability of movements. The present study aimed to elucidate the role of nitric oxide (NO) in the modulation of mammalian spinal locomotor networks. This was investigated with isolated spinal cord preparations from neonatal mice in which rhythmic locomotor-related activity was induced pharmacologically. Bath application of the NO donor diethylamine NONOate (DEA/NO) decreased the frequency and modulated the amplitude of locomotor-related activity recorded from ventral roots. Removal of endogenous NO with coapplication of a NO scavenger (PTIO) and a nitric oxide synthase (NOS) blocker [nitro-l-arginine methyl ester (l-NAME)] increased the frequency and decreased the amplitude of locomotor-related activity. This demonstrates that endogenously derived NO can modulate both the timing and intensity of locomotor-related activity. The effects of DEA/NO were mimicked by the cGMP analog 8-bromo-cGMP. In addition, the soluble guanylyl cyclase (sGC) inhibitor ODQ blocked the effects of DEA/NO on burst amplitude and frequency, although the frequency effect was only blocked at low concentrations of DEA/NO. This suggests that NO-mediated modulation involves cGMP-dependent pathways. Sources of NO were studied within the lumbar spinal cord during postnatal development (postnatal days 1-12) with NADPH-diaphorase staining. NOS-positive cells in the ventral horn exhibited a rostrocaudal gradient, with more cells in rostral segments. The number of NOS-positive cells was also found to increase during postnatal development. In summary, we have shown that NO, derived from sources within the mammalian spinal cord, modulates the output of spinal motor networks and is therefore likely to contribute to the fine-tuning of locomotor behavior.

  18. Survivability design for a hybrid underwater vehicle

    SciTech Connect

    Wang, Biao; Wu, Chao; Li, Xiang; Zhao, Qingkai; Ge, Tong

    2015-03-10

    A novel hybrid underwater robotic vehicle (HROV) capable of working to the full ocean depth has been developed. The battery powered vehicle operates in two modes: operate as an untethered autonomous vehicle in autonomous underwater vehicle (AUV) mode and operate under remote control connected to the surface vessel by a lightweight, fiber optic tether in remotely operated vehicle (ROV) mode. Considering the hazardous underwater environment at the limiting depth and the hybrid operating modes, survivability has been placed on an equal level with the other design attributes of the HROV since the beginning of the project. This paper reports the survivability design elements for the HROV including basic vehicle design of integrated navigation and integrated communication, emergency recovery strategy, distributed architecture, redundant bus, dual battery package, emergency jettison system and self-repairing control system.

  19. Integrated Locomotor Function Tests for Countermeasure Evaluation

    NASA Technical Reports Server (NTRS)

    Bloomberg, J. J.; Mulavara, A. P.; Peters, B. T.; Cohen, H. S.; Landsness, E. C.; Black, F. O.

    2005-01-01

    Following spaceflight crewmembers experience locomotor dysfunction due to inflight adaptive alterations in sensorimotor function. Countermeasures designed to mitigate these postflight gait alterations need to be assessed with a new generation of tests that evaluate the interaction of various sensorimotor sub-systems central to locomotor control. The goal of the present study was to develop new functional tests of locomotor control that could be used to test the efficacy of countermeasures. These tests were designed to simultaneously examine the function of multiple sensorimotor systems underlying the control of locomotion and be operationally relevant to the astronaut population. Traditionally, gaze stabilization has been studied almost exclusively in seated subjects performing target acquisition tasks requiring only the involvement of coordinated eye-head movements. However, activities like walking involve full-body movement and require coordination between lower limbs and the eye-head-trunk complex to achieve stabilized gaze during locomotion. Therefore the first goal of this study was to determine how the multiple, interdependent, full-body sensorimotor gaze stabilization subsystems are functionally coordinated during locomotion. In an earlier study we investigated how alteration in gaze tasking changes full-body locomotor control strategies. Subjects walked on a treadmill and either focused on a central point target or read numeral characters. We measured: temporal parameters of gait, full body sagittal plane segmental kinematics of the head, trunk, thigh, shank and foot, accelerations along the vertical axis at the head and the shank, and the vertical forces acting on the support surface. In comparison to the point target fixation condition, the results of the number reading task showed that compensatory head pitch movements increased, peak head acceleration was reduced and knee flexion at heel-strike was increased. In a more recent study we investigated the

  20. Locomotor training: experiencing the changing body.

    PubMed

    Hannold, Elizabeth M; Young, Mary Ellen; Rittman, Maude R; Bowden, Mark G; Behrman, Andrea L

    2006-01-01

    This study examined the experiences of persons with incomplete spinal cord injury who participated in loco-motor training (LT). LT is an emerging rehabilitation intervention for enhancing the recovery of walking in persons with central nervous system disorders. Multiple interviews and field observations provided data from eight participants, including four veterans. Findings indicate that experiences of bodily changes were prevalent among participants. Themes included (1) experiencing impaired or absent proprioception, (2) struggling for bodily control, and (3) experiencing emergent bodily sensations. Themes 1 and 2 reflected bodily disruption as a result of spinal cord injury and were challenging to participants as they attempted to reconnect the body and self through LT. Theme 3 reflected bodily sensations (burning, soreness) that were seen as positive signs of recovery and resulted in hope and motivation. Understanding how LT participants experience bodily changes may enable therapists to develop improved participant-centered intervention approaches.

  1. Underwater Sensor Network Redeployment Algorithm Based on Wolf Search

    PubMed Central

    Jiang, Peng; Feng, Yang; Wu, Feng

    2016-01-01

    This study addresses the optimization of node redeployment coverage in underwater wireless sensor networks. Given that nodes could easily become invalid under a poor environment and the large scale of underwater wireless sensor networks, an underwater sensor network redeployment algorithm was developed based on wolf search. This study is to apply the wolf search algorithm combined with crowded degree control in the deployment of underwater wireless sensor networks. The proposed algorithm uses nodes to ensure coverage of the events, and it avoids the prematurity of the nodes. The algorithm has good coverage effects. In addition, considering that obstacles exist in the underwater environment, nodes are prevented from being invalid by imitating the mechanism of avoiding predators. Thus, the energy consumption of the network is reduced. Comparative analysis shows that the algorithm is simple and effective in wireless sensor network deployment. Compared with the optimized artificial fish swarm algorithm, the proposed algorithm exhibits advantages in network coverage, energy conservation, and obstacle avoidance. PMID:27775659

  2. Autonomous underwater pipeline monitoring navigation system

    NASA Astrophysics Data System (ADS)

    Mitchell, Byrel; Mahmoudian, Nina; Meadows, Guy

    2014-06-01

    This paper details the development of an autonomous motion-control and navigation algorithm for an underwater autonomous vehicle, the Ocean Server IVER3, to track long linear features such as underwater pipelines. As part of this work, the Nonlinear and Autonomous Systems Laboratory (NAS Lab) developed an algorithm that utilizes inputs from the vehicles state of the art sensor package, which includes digital imaging, digital 3-D Sidescan Sonar, and Acoustic Doppler Current Profilers. The resulting algorithms should tolerate real-world waterway with episodic strong currents, low visibility, high sediment content, and a variety of small and large vessel traffic.

  3. Resources for Underwater Robotics Education

    ERIC Educational Resources Information Center

    Wallace, Michael L.; Freitas, William M.

    2016-01-01

    4-H clubs can build and program underwater robots from raw materials. An annotated resource list for engaging youth in building underwater remotely operated vehicles (ROVs) is provided. This article is a companion piece to the Research in Brief article "Building Teen Futures with Underwater Robotics" in this issue of the "Journal of…

  4. Advanced underwater lift device

    NASA Technical Reports Server (NTRS)

    Flanagan, David T.; Hopkins, Robert C.

    1993-01-01

    Flexible underwater lift devices ('lift bags') are used in underwater operations to provide buoyancy to submerged objects. Commercially available designs are heavy, bulky, and awkward to handle, and thus are limited in size and useful lifting capacity. An underwater lift device having less than 20 percent of the bulk and less than 10 percent of the weight of commercially available models was developed. The design features a dual membrane envelope, a nearly homogeneous envelope membrane stress distribution, and a minimum surface-to-volume ratio. A proof-of-concept model of 50 kg capacity was built and tested. Originally designed to provide buoyancy to mock-ups submerged in NASA's weightlessness simulators, the device may have application to water-landed spacecraft which must deploy flotation upon impact, and where launch weight and volume penalties are significant. The device may also be useful for the automated recovery of ocean floor probes or in marine salvage applications.

  5. Underwater vehicle propulsion and power generation

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor); Chao, Yi (Inventor)

    2008-01-01

    An underwater vehicle includes a shaft with a propeller disposed thereon; a generator/motor having a stator and a rotor, the rotor being operable to rotate with the propeller; at least one energy storage device connected to the generator/motor; and a controller for setting the generator/motor in a charge mode, a propulsion mode and an idle mode.

  6. NaNet3: The on-shore readout and slow-control board for the KM3NeT-Italia underwater neutrino telescope

    NASA Astrophysics Data System (ADS)

    Ammendola, R.; Biagioni, A.; Frezza, O.; Lo Cicero, F.; Martinelli, M.; Paolucci, P. S.; Pontisso, L.; Simula, F.; Vicini, P.; Ameli, F.; Nicolau, C. A.; Pastorelli, E.; Simeone, F.; Tosoratto, L.; Lonardo, A.

    2016-04-01

    The KM3NeT-Italia underwater neutrino detection unit, the tower, consists of 14 floors. Each floor supports 6 Optical Modules containing front-end electronics needed to digitize the PMT signal, format and transmit the data and 2 hydrophones that reconstruct in real-time the position of Optical Modules, for a maximum tower throughput of more than 600 MB/s. All floor data are collected by the Floor Control Module (FCM) board and transmitted by optical bidirectional virtual point-to-point connections to the on-shore laboratory, each FCM needing an on-shore counterpart as communication endpoint. In this contribution we present NaNet3, an on-shore readout board based on Altera Stratix V GX FPGA able to manage multiple FCM data channels with a capability of 800 Mbps each. The design is a NaNet customization for the KM3NeT-Italia experiment, adding support in its I/O interface for a synchronous link protocol with deterministic latency at physical level and for a Time Division Multiplexing protocol at data level.

  7. Interpreting locomotor biomechanics from the morphology of human footprints.

    PubMed

    Hatala, Kevin G; Wunderlich, Roshna E; Dingwall, Heather L; Richmond, Brian G

    2016-01-01

    Fossil hominin footprints offer unique direct windows to the locomotor behaviors of our ancestors. These data could allow a clearer understanding of the evolution of human locomotion by circumventing issues associated with indirect interpretations of habitual locomotor patterns from fossil skeletal material. However, before we can use fossil hominin footprints to understand better the evolution of human locomotion, we must first develop an understanding of how locomotor biomechanics are preserved in, and can be inferred from, footprint morphologies. In this experimental study, 41 habitually barefoot modern humans created footprints under controlled conditions in which variables related to locomotor biomechanics could be quantified. Measurements of regional topography (depth) were taken from 3D models of those footprints, and principal components analysis was used to identify orthogonal axes that described the largest proportions of topographic variance within the human experimental sample. Linear mixed effects models were used to quantify the influences of biomechanical variables on the first five principal axes of footprint topographic variation, thus providing new information on the biomechanical variables most evidently expressed in the morphology of human footprints. The footprint's overall depth was considered as a confounding variable, since biomechanics may be linked to the extent to which a substrate deforms. Three of five axes showed statistically significant relationships with variables related to both locomotor biomechanics and substrate displacement; one axis was influenced only by biomechanics and another only by the overall depth of the footprint. Principal axes of footprint morphological variation were significantly related to gait type (walking or running), kinematics of the hip and ankle joints and the distribution of pressure beneath the foot. These results provide the first quantitative framework for developing hypotheses regarding the

  8. Design and implementation of an omni-directional underwater acoustic micro-modem based on a low-power micro-controller unit.

    PubMed

    Won, Tae-Hee; Park, Sung-Joon

    2012-01-01

    For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense of large size and high power consumption. Recently, as the need for underwater wireless sensor networks (UWSNs) has increased, the research and development of compact and low-power consuming communication devices has become the focus. From the consideration that the requisites of acoustic modems for UWSNs are low power consumption, omni-directional beam pattern, low cost and so on, in this paper, we design and implement an omni-directional underwater acoustic micro-modem satisfying these requirements. In order to execute fast digital domain signal processing and support flexible interfaces with other peripherals, an ARM Cortex-M3 is embedded in the micro-modem. Also, for the realization of small and omni-directional properties, a spherical transducer having a resonant frequency of 70 kHz and a diameter of 34 mm is utilized for the implementation. Physical layer frame format and symbol structure for efficient packet-based underwater communication systems are also investigated. The developed acoustic micro-modem is verified analytically and experimentally in indoor and outdoor environments in terms of functionality and performance. Since the modem satisfies the requirements for use in UWSNs, it could be deployed in a wide range of applications requiring underwater acoustic communication.

  9. Design and Implementation of an Omni-Directional Underwater Acoustic Micro-Modem Based on a Low-Power Micro-Controller Unit

    PubMed Central

    Won, Tae-Hee; Park, Sung-Joon

    2012-01-01

    For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense of large size and high power consumption. Recently, as the need for underwater wireless sensor networks (UWSNs) has increased, the research and development of compact and low-power consuming communication devices has become the focus. From the consideration that the requisites of acoustic modems for UWSNs are low power consumption, omni-directional beam pattern, low cost and so on, in this paper, we design and implement an omni-directional underwater acoustic micro-modem satisfying these requirements. In order to execute fast digital domain signal processing and support flexible interfaces with other peripherals, an ARM Cortex-M3 is embedded in the micro-modem. Also, for the realization of small and omni-directional properties, a spherical transducer having a resonant frequency of 70 kHz and a diameter of 34 mm is utilized for the implementation. Physical layer frame format and symbol structure for efficient packet-based underwater communication systems are also investigated. The developed acoustic micro-modem is verified analytically and experimentally in indoor and outdoor environments in terms of functionality and performance. Since the modem satisfies the requirements for use in UWSNs, it could be deployed in a wide range of applications requiring underwater acoustic communication. PMID:22438765

  10. Muscle spindle feedback directs locomotor recovery and circuit reorganization after spinal cord injury.

    PubMed

    Takeoka, Aya; Vollenweider, Isabel; Courtine, Grégoire; Arber, Silvia

    2014-12-18

    Spinal cord injuries alter motor function by disconnecting neural circuits above and below the lesion, rendering sensory inputs a primary source of direct external drive to neuronal networks caudal to the injury. Here, we studied mice lacking functional muscle spindle feedback to determine the role of this sensory channel in gait control and locomotor recovery after spinal cord injury. High-resolution kinematic analysis of intact mutant mice revealed proficient execution in basic locomotor tasks but poor performance in a precision task. After injury, wild-type mice spontaneously recovered basic locomotor function, whereas mice with deficient muscle spindle feedback failed to regain control over the hindlimb on the lesioned side. Virus-mediated tracing demonstrated that mutant mice exhibit defective rearrangements of descending circuits projecting to deprived spinal segments during recovery. Our findings reveal an essential role for muscle spindle feedback in directing basic locomotor recovery and facilitating circuit reorganization after spinal cord injury.

  11. Study on underwater wireless communication system using LED

    NASA Astrophysics Data System (ADS)

    Son, Hyun-Joong; Choi, Hyeung-Sik; Tran, Ngoc-Huy; Ha, Ji-Hoon; Ji, Dae-Hyeung; Kim, Joon-Young

    2015-03-01

    In this paper, a new variable-focus LED light device is developed for underwater communication. Usually used as an underwater lighting fixture, the LED light device in this study is utilized as an underwater communication device (UCD) by controlling the distance between light source and lens when communication is needed. A transmission and a receiving part of LED light for communication using photoelectric sensor and Fresnel lens are also developed. The communication system was tested in fresh water and sea water to verify its communication performance; results of which are presented in this study.

  12. Locomotor behavior of fish hatched from embryos exposed to flight conditions

    NASA Technical Reports Server (NTRS)

    Kleerekoper, H.

    1978-01-01

    Embryos of Fundulus heteroclitus in various stages of development were exposed to space flight conditions aboard Apollo spacecraft and Cosmos satellites. The objective of the study was to ascertain whether fish hatched from these embryos displayed locomotor behavior different from that of control fish of the same age. An electronic monitoring technique was used to record behavior. Results indicate no change in locomotor behavior in fish on Apollo Spacecraft, but inexplicable significant changes were noted in fish aboard Cosmos Satellites.

  13. Development of a Countermeasure to Enhance Postflight Locomotor Adaptability

    NASA Technical Reports Server (NTRS)

    Bloomberg, Jacob J.

    2006-01-01

    Astronauts returning from space flight experience locomotor dysfunction following their return to Earth. Our laboratory is currently developing a gait adaptability training program that is designed to facilitate recovery of locomotor function following a return to a gravitational environment. The training program exploits the ability of the sensorimotor system to generalize from exposure to multiple adaptive challenges during training so that the gait control system essentially learns to learn and therefore can reorganize more rapidly when faced with a novel adaptive challenge. We have previously confirmed that subjects participating in adaptive generalization training programs using a variety of visuomotor distortions can enhance their ability to adapt to a novel sensorimotor environment. Importantly, this increased adaptability was retained even one month after completion of the training period. Adaptive generalization has been observed in a variety of other tasks requiring sensorimotor transformations including manual control tasks and reaching (Bock et al., 2001, Seidler, 2003) and obstacle avoidance during walking (Lam and Dietz, 2004). Taken together, the evidence suggests that a training regimen exposing crewmembers to variation in locomotor conditions, with repeated transitions among states, may enhance their ability to learn how to reassemble appropriate locomotor patterns upon return from microgravity. We believe exposure to this type of training will extend crewmembers locomotor behavioral repertoires, facilitating the return of functional mobility after long duration space flight. Our proposed training protocol will compel subjects to develop new behavioral solutions under varying sensorimotor demands. Over time subjects will learn to create appropriate locomotor solution more rapidly enabling acquisition of mobility sooner after long-duration space flight. Our laboratory is currently developing adaptive generalization training procedures and the

  14. Dynamics and plasticity of spinal locomotor circuits.

    PubMed

    El Manira, Abdeljabbar

    2014-12-01

    Spinal circuits generate coordinated locomotor movements. These hardwired circuits are supplemented with neuromodulation that provide the necessary flexibility for animals to move smoothly through their environment. This review will highlight some recent insights gained in understanding the functional dynamics and plasticity of the locomotor circuits. First the mechanisms governing the modulation of the speed of locomotion will be discussed. Second, advantages of the modular organization of the locomotor networks with multiple circuits engaged in a task-dependent manner will be examined. Finally, the neuromodulation and the resulting plasticity of the locomotor circuits will be summarized with an emphasis on endocannabinoids and nitric oxide. The intention is to extract general principles of organization and discuss some onto-genetic and phylogenetic divergences.

  15. Repeatability of locomotor performance and morphology-locomotor performance relationships.

    PubMed

    Conradsen, Cara; Walker, Jeffrey A; Perna, Catherine; McGuigan, Katrina

    2016-09-15

    There is good evidence that natural selection drives the evolution of locomotor performance, but the processes that generate the among-individual variation for selection to act on are relatively poorly understood. We measured prolonged swimming performance, Ucrit, and morphology in a large cohort (n=461) of wild-type zebrafish (Danio rerio) at ∼6 months and again at ∼9 months. Using mixed-model analyses to estimate repeatability as the intraclass correlation coefficient, we determined that Ucrit was significantly repeatable (r=0.55; 95% CI: 0.45-0.64). Performance differences between the sexes (males 12% faster than females) and changes with age (decreasing 0.07% per day) both contributed to variation in Ucrit and, therefore, the repeatability estimate. Accounting for mean differences between sexes within the model decreased the estimate of Ucrit repeatability to 21% below the naïve estimate, while fitting age in the models increased the estimate to 14% above the naïve estimate. Greater consideration of factors such as age and sex is therefore necessary for the interpretation of performance repeatability in wild populations. Body shape significantly predicted Ucrit in both sexes in both assays, with the morphology-performance relationship significantly repeatable at the population level. However, morphology was more strongly predicative of performance in older fish, suggesting a change in the contribution of morphology relative to other factors such as physiology and behaviour. The morphology-performance relationship changed with age to a greater extent in males than females.

  16. Underwater welding, cutting and inspection

    SciTech Connect

    Tsai, C.L. . Ohio Underwater Welding Center)

    1995-02-01

    Underwater welding, cutting and inspection of offshore, inland waterway and port facilities are becoming a requirement for both military and industrial communities, as maintenance and repair costs continue to escalate, and as many of the facilities are in operation well beyond their intended design life. In nuclear applications, underwater welding, cutting and inspection for repair and modification of irradiated nuclear power plant components are also a requirement. This article summarizes recent developments in this emerging underwater technology.

  17. In Situ Control of Underwater-Pinning of Organic Droplets on a Surfactant-Doped Conjugated Polymer Surface.

    PubMed

    Xu, Wei; Xu, Jian; Choi, Chang-Hwan; Yang, Eui-Hyeok

    2015-11-25

    Controlling the pinning of organic droplets on solid surfaces is of fundamental and practical interest in the field of material science and engineering, which has numerous applications such as surface cleaning, water treatment, and microfluidics. Here, a rapid in situ control of pinning and actuation of organic droplets is demonstrated on dodecylbenzenesulfonate-doped polypyrrole (PPy(DBS)) surfaces in an aqueous environment via an electrochemical redox process. A dramatic change of the pinning results from the transport of DBS(-) molecules between the PPy(DBS) surface and the aqueous environment, as well as from a simultaneous alternation of the surface oleophobicity to organic liquids during the redox process. This in situ control of the droplet pinning enables a stop-and-go droplet actuation, applicable to both polar and apolar organic droplets, at low voltages (∼0.9 V) with an extremely low roll-off angle (∼0.4°).

  18. Design and Initial In-Water Testing of Advanced Non-Linear Control Algorithms onto an Unmanned Underwater Vehicle (UUV)

    DTIC Science & Technology

    2007-10-01

    controllable speeds, the ability to maintain a set distance and attitude ( pitch and roll ) relative to some surface for optimal sensor (both sonar and...bottom by adjusting its pitch and roll based on the information coming from the sonar sensor. Another task for the vehicle was to track a line along...are the roll , pitch , and yaw backstepping terms, Θbs. For attitude control, based on eqn. (2), we define the signal ωoc = Ω −1 ( −KΘΘ̃ + Θ̇c −Θbs

  19. NEW APPROACHES: Vision underwater

    NASA Astrophysics Data System (ADS)

    Steele, Alan L.

    1997-11-01

    A tutorial type problem examining the focusing performance of the human eye in air and in water is solved by two different approaches. Calculations show that light can be effectively focused on the retina when the eye is in air but not underwater, even with the usual accommodation. We then examine how some vertebrates have accommodation processes that permit them to see effectively both above and below water.

  20. Underwater laser detection system

    NASA Astrophysics Data System (ADS)

    Gomaa, Walid; El-Sherif, Ashraf F.; El-Sharkawy, Yasser H.

    2015-02-01

    The conventional method used to detect an underwater target is by sending and receiving some form of acoustic energy. But the acoustic systems have limitations in the range resolution and accuracy; while, the potential benefits of a laserbased underwater target detection include high directionality, high response, and high range accuracy. Lasers operating in the blue-green region of the light spectrum(420 : 570nm)have a several applications in the area of detection and ranging of submersible targets due to minimum attenuation through water ( less than 0.1 m-1) and maximum laser reflection from estimated target (like mines or submarines) to provide a long range of detection. In this paper laser attenuation in water was measured experimentally by new simple method by using high resolution spectrometer. The laser echoes from different targets (metal, plastic, wood, and rubber) were detected using high resolution CCD camera; the position of detection camera was optimized to provide a high reflection laser from target and low backscattering noise from the water medium, digital image processing techniques were applied to detect and discriminate the echoes from the metal target and subtract the echoes from other objects. Extraction the image of target from the scattering noise is done by background subtraction and edge detection techniques. As a conclusion, we present a high response laser imaging system to detect and discriminate small size, like-mine underwater targets.

  1. Locomotor sequence learning in visually guided walking.

    PubMed

    Choi, Julia T; Jensen, Peter; Nielsen, Jens Bo

    2016-04-01

    Voluntary limb modifications must be integrated with basic walking patterns during visually guided walking. In this study we tested whether voluntary gait modifications can become more automatic with practice. We challenged walking control by presenting visual stepping targets that instructed subjects to modify step length from one trial to the next. Our sequence learning paradigm is derived from the serial reaction-time (SRT) task that has been used in upper limb studies. Both random and ordered sequences of step lengths were used to measure sequence-specific and sequence-nonspecific learning during walking. In addition, we determined how age (i.e., healthy young adults vs. children) and biomechanical factors (i.e., walking speed) affected the rate and magnitude of locomotor sequence learning. The results showed that healthy young adults (age 24 ± 5 yr,n= 20) could learn a specific sequence of step lengths over 300 training steps. Younger children (age 6-10 yr,n= 8) had lower baseline performance, but their magnitude and rate of sequence learning were the same compared with those of older children (11-16 yr,n= 10) and healthy adults. In addition, learning capacity may be more limited at faster walking speeds. To our knowledge, this is the first study to demonstrate that spatial sequence learning can be integrated with a highly automatic task such as walking. These findings suggest that adults and children use implicit knowledge about the sequence to plan and execute leg movement during visually guided walking.

  2. Organization of mammalian locomotor rhythm and pattern generation

    PubMed Central

    McCrea, David A.; Rybak, Ilya A.

    2008-01-01

    Central pattern generators (CPGs) located in the spinal cord produce the coordinated activation of flexor and extensor motoneurons during locomotion. Previously proposed architectures for the spinal locomotor CPG have included the classical half-center oscillator and the unit burst generator (UBG) comprised of multiple coupled oscillators. We have recently proposed another organization in which a two-level CPG has a common rhythm generator (RG) that controls the operation of the pattern formation (PF) circuitry responsible for motoneuron activation. These architectures are discussed in relation to recent data obtained during fictive locomotion in the decerebrate cat. The data show that the CPG can maintain the period and phase of locomotor oscillations both during spontaneous deletions of motoneuron activity and during sensory stimulation affecting motoneuron activity throughout the limb. The proposed two-level CPG organization has been investigated with a computational model which incorporates interactions between the CPG, spinal circuits and afferent inputs. The model includes interacting populations of spinal interneurons and motoneurons modeled in the Hodgkin-Huxley style. Our simulations demonstrate that a relatively simple CPG with separate RG and PF networks can realistically reproduce many experimental phenomena including spontaneous deletions of motoneuron activity and a variety of effects of afferent stimulation. The model suggests plausible explanations for a number of features of real CPG operation that would be difficult to explain in the framework of the classical single-level CPG organization. Some modeling predictions and directions for further studies of locomotor CPG organization are discussed. PMID:17936363

  3. NOESY-WaterControl: a new NOESY sequence for the observation of under-water protein resonances.

    PubMed

    Torres, Allan M; Zheng, Gang; Price, William S

    2017-03-07

    Highly selective and efficient water signal suppression is indispensable in biomolecular 2D nuclear Overhauser effect spectroscopy (NOESY) experiments. However, the application of conventional water suppression schemes can cause a significant or complete loss of the biomolecular resonances at and around the water chemical shift (ω2). In this study, a new sequence, NOESY-WaterControl, was developed to address this issue. The new sequence was tested on lysozyme and bovine pancreatic trypsin inhibitor (BPTI), demonstrating its efficiency in both water suppression and, more excitingly, preserving water-proximate biomolecular resonances in ω2. The 2D NOESY maps obtained using the new sequence thus provide more information than the maps obtained with conventional water suppression, thereby lessening the number of experiments needed to complete resonance assignments of biomolecules. The 2D NOESY-WaterControl map of BPTI showed strong bound water and exchangeable proton signals in ω1 but these signals were absent in ω2, indicating the possibility of using the new sequence to discriminate bound water and exchangeable proton resonances from non-labile proton resonances with similar chemical shifts to water.

  4. Effect of locomotor training in completely spinalized cats previously submitted to a spinal hemisection.

    PubMed

    Martinez, Marina; Delivet-Mongrain, Hugo; Leblond, Hugues; Rossignol, Serge

    2012-08-08

    After a spinal hemisection in cats, locomotor plasticity occurring at the spinal level can be revealed by performing, several weeks later, a complete spinalization below the first hemisection. Using this paradigm, we recently demonstrated that the hemisection induces durable changes in the symmetry of locomotor kinematics that persist after spinalization. Can this asymmetry be changed again in the spinal state by interventions such as treadmill locomotor training started within a few days after the spinalization? We performed, in 9 adult cats, a spinal hemisection at thoracic level 10 and then a complete spinalization at T13, 3 weeks later. Cats were not treadmill trained during the hemispinal period. After spinalization, 5 of 9 cats were not trained and served as control while 4 of 9 cats were trained on the treadmill for 20 min, 5 d a week for 3 weeks. Using detailed kinematic analyses, we showed that, without training, the asymmetrical state of locomotion induced by the hemisection was retained durably after the subsequent spinalization. By contrast, training cats after spinalization induced a reversal of the left/right asymmetries, suggesting that new plastic changes occurred within the spinal cord through locomotor training. Moreover, training was shown to improve the kinematic parameters and the performance of the hindlimb on the previously hemisected side. These results indicate that spinal locomotor circuits, previously modified by past experience such as required for adaptation to the hemisection, can remarkably respond to subsequent locomotor training and improve bilateral locomotor kinematics, clearly showing the benefits of locomotor training in the spinal state.

  5. Treadmill exercise facilitates recovery of locomotor function through axonal regeneration following spinal cord injury in rats

    PubMed Central

    Jung, Sun-Young; Seo, Tae-Beom; Kim, Dae-Young

    2016-01-01

    Spinal cord injury (SCI) disrupts both axonal pathways and segmental spinal cord circuity, resulting in permanent neurological deficits. Physical exercise is known to increase the expression of neurotrophins for improving the injured spinal cord. In the present study, we investigated the effects of treadmill exercise on locomotor function in relation with brain-derived neurotrophic factor (BDNF) expression after SCI. The rats were divided into five groups: control group, sham operation group, sham operation and exercise group, SCI group, and SCI and exercise group. The laminectomy was performed at the T9–T10 level. The exposed dorsal surface of the spinal cord received contusion injury (10 g × 25 mm) using the impactor. Treadmill exercise was performed 6 days per a week for 6 weeks. In order to evaluate the locomotor function of animals, Basso-Beattie-Bresnahan (BBB) locomotor scale was conducted once a week for 6 weeks. We examined BDNF expression and axonal sprouting in the injury site of the spinal cord using Western blot analysis and immunofluorescence staining. SCI induced loss of locomotor function with decreased BDNF expression in the injury site. Treadmill exercise increased the score of BBB locomotor scale and reduced cavity formation in the injury site. BDNF expression and axonal sprouting within the trabecula were further facilitated by treadmill exercise in SCI-exposed rats. The present study provides the evidence that treadmill exercise may facilitate recovery of locomotor function through axonal regeneration via BDNF expression following SCI. PMID:27656624

  6. Effects of sex pheromones and sexual maturation on locomotor activity in female sea lamprey (Petromyzon marinus)

    USGS Publications Warehouse

    Walaszczyk, Erin J.; Johnson, Nicholas S.; Steibel, Juan Pedro; Li, Weiming

    2013-01-01

    Synchronization of male and female locomotor rhythmicity can play a vital role in ensuring reproductive success. Several physiological and environmental factors alter these locomotor rhythms. As sea lamprey, Petromyzon marinus, progress through their life cycle, their locomotor activity rhythm changes multiple times. The goal of this study was to elucidate the activity patterns of adult female sea lamprey during the sexual maturation process and discern the interactions of these patterns with exposure to male pheromones. During these stages, preovulated and ovulated adult females are exposed to sex pheromone compounds, which are released by spermiated males and attract ovulated females to the nest for spawning. The locomotor behavior of adult females was monitored in a natural stream with a passive integrated tag responder system as they matured, and they were exposed to a sex pheromone treatment (spermiated male washings) or a control (prespermiated male washings). Results showed that, dependent on the hour of day, male sex pheromone compounds reduce total activity (p < 0.05) and cause increases in activity during several daytime hours in preovulated and ovulated females. These results are one of the first examples of how sex pheromones modulate a locomotor rhythm in a vertebrate, and they suggest that the interaction between maturity stage and sex pheromone exposure contributes to the differential locomotor rhythms found in adult female sea lamprey. This phenomenon may contribute to the reproductive synchrony of mature adults, thus increasing reproductive success in this species.

  7. Overview of a hybrid underwater camera system

    NASA Astrophysics Data System (ADS)

    Church, Philip; Hou, Weilin; Fournier, Georges; Dalgleish, Fraser; Butler, Derek; Pari, Sergio; Jamieson, Michael; Pike, David

    2014-05-01

    The paper provides an overview of a Hybrid Underwater Camera (HUC) system combining sonar with a range-gated laser camera system. The sonar is the BlueView P900-45, operating at 900kHz with a field of view of 45 degrees and ranging capability of 60m. The range-gated laser camera system is based on the third generation LUCIE (Laser Underwater Camera Image Enhancer) sensor originally developed by the Defence Research and Development Canada. LUCIE uses an eye-safe laser generating 1ns pulses at a wavelength of 532nm and at the rate of 25kHz. An intensified CCD camera operates with a gating mechanism synchronized with the laser pulse. The gate opens to let the camera capture photons from a given range of interest and can be set from a minimum delay of 5ns with increments of 200ps. The output of the sensor is a 30Hz video signal. Automatic ranging is achieved using a sonar altimeter. The BlueView sonar and LUCIE sensors are integrated with an underwater computer that controls the sensors parameters and displays the real-time data for the sonar and the laser camera. As an initial step for data integration, graphics overlays representing the laser camera field-of-view along with the gate position and width are overlaid on the sonar display. The HUC system can be manually handled by a diver and can also be controlled from a surface vessel through an umbilical cord. Recent test data obtained from the HUC system operated in a controlled underwater environment will be presented along with measured performance characteristics.

  8. Evaluation of Underwater Welding and Cutting Equipment Available in 1969.

    DTIC Science & Technology

    UNDERWATER CUTTING, TORCHES), (*ARC WELDING , UNDERWATER EQUIPMENT), (*UNDERWATER EQUIPMENT, STATISTICAL DATA), SALVAGE, WELDABILITY, PERFORMANCE(ENGINEERING), PERFORMANCE(HUMAN), ANALYSIS OF VARIANCE.

  9. Optimal Sensor Layouts in Underwater Locomotory Systems

    NASA Astrophysics Data System (ADS)

    Colvert, Brendan; Kanso, Eva

    2015-11-01

    Retrieving and understanding global flow characteristics from local sensory measurements is a challenging but extremely relevant problem in fields such as defense, robotics, and biomimetics. It is an inverse problem in that the goal is to translate local information into global flow properties. In this talk we present techniques for optimization of sensory layouts within the context of an idealized underwater locomotory system. Using techniques from fluid mechanics and control theory, we show that, under certain conditions, local measurements can inform the submerged body about its orientation relative to the ambient flow, and allow it to recognize local properties of shear flows. We conclude by commenting on the relevance of these findings to underwater navigation in engineered systems and live organisms.

  10. Underwater splice for submarine coaxial cable

    SciTech Connect

    Inouye, A.T.; Roe, T. Jr.; Tausing, W.R.; Wilson, J.V.

    1984-10-30

    The invention is a device for splicing submarine coaxial cable underwater on the seafloor with a simple push-on operation to restore and maintain electrical and mechanical strength integrity; the splice device is mateable directly with the severed ends of a coaxial cable to be repaired. Splicing assemblies comprise a dielectric pressure compensating fluid filled guide cavity, a gelled castor oil cap and wiping seals for exclusion of seawater, electrical contacts, a cable strength restoration mechanism, and a pressure compensation system for controlled extrusion of and depletion loss prevention of dielectric seal fluid during cable splicing. A splice is made underwater by directly inserting prepared ends of coaxial cable, having no connector attachments, into splicing assemblies.

  11. Loudness for tone underwater

    NASA Astrophysics Data System (ADS)

    Cudahy, Edward; Schwaller, Derek

    2002-05-01

    The loudness for pure tones was measured by loudness matching for 1-s pure tones from 100 to 50000 Hz. The standard tone was 1000 Hz. Subjects were instructed to match the loudness of the comparison tone at one of the test frequencies to the loudness of the standard tone. The standard was presented at one of five sound pressure levels (SPL) for each set of frequencies. The standard SPL was varied randomly across test series. The subjects were bareheaded US Navy divers tested at a depth of 3 m. All subjects had normal hearing. The tones were presented to the right side of the subject from an array of underwater sound projectors. The SPL was calibrated at the location of the subject's head with the subject absent. The loudness increased more rapidly as a function of standard SPL at mid-frequencies than at either high or low frequencies. The most compact loudness contours (least SPL change across range of standard SPL) were at 50000 Hz. The underwater loudness contours across frequency are significantly different from in-air measurements and have a minimum in the 1000 Hz region rather than the 2-4 kHz region observed for in-air measurements. [Work supported by ONR.

  12. Underwater Hearing in Turtles.

    PubMed

    Willis, Katie L

    2016-01-01

    The hearing of turtles is poorly understood compared with the other reptiles. Although the mechanism of transduction of sound into a neural signal via hair cells has been described in detail, the rest of the auditory system is largely a black box. What is known is that turtles have higher hearing thresholds than other reptiles, with best frequencies around 500 Hz. They also have lower underwater hearing thresholds than those in air, owing to resonance of the middle ear cavity. Further studies demonstrated that all families of turtles and tortoises share a common middle ear cavity morphology, with scaling best suited to underwater hearing. This supports an aquatic origin of the group. Because turtles hear best under water, it is important to examine their vulnerability to anthropogenic noise. However, the lack of basic data makes such experiments difficult because only a few species of turtles have published audiograms. There are also almost no behavioral data available (understandable due to training difficulties). Finally, few studies show what kinds of sounds are behaviorally relevant. One notable paper revealed that the Australian snake-necked turtle (Chelodina oblonga) has a vocal repertoire in air, at the interface, and under water. Findings like these suggest that there is more to the turtle aquatic auditory scene than previously thought.

  13. Underwater reflectance transformation imaging: a technology for in situ underwater cultural heritage object-level recording

    NASA Astrophysics Data System (ADS)

    Selmo, David; Sturt, Fraser; Miles, James; Basford, Philip; Malzbender, Tom; Martinez, Kirk; Thompson, Charlie; Earl, Graeme; Bevan, George

    2017-01-01

    There is an increasing demand for high-resolution recording of in situ underwater cultural heritage. Reflectance transformation imaging (RTI) has a proven track record in terrestrial contexts for acquiring high-resolution diagnostic data at small scales. The research presented here documents the first adaptation of RTI protocols to the subaquatic environment, with a scuba-deployable method designed around affordable off-the-shelf technologies. Underwater RTI (URTI) was used to capture detail from historic shipwrecks in both the Solent and the western Mediterranean. Results show that URTI can capture submillimeter levels of qualitative diagnostic detail from in situ archaeological material. In addition, this paper presents the results of experiments to explore the impact of turbidity on URTI. For this purpose, a prototype fixed-lighting semisubmersible RTI photography dome was constructed to allow collection of data under controlled conditions. The signal-to-noise data generated reveals that the RGB channels of underwater digital images captured in progressive turbidity degraded faster than URTI object geometry calculated from them. URTI is shown to be capable of providing analytically useful object-level detail in conditions that would render ordinary underwater photography of limited use.

  14. Adaptive locomotor behavior in larval zebrafish.

    PubMed

    Portugues, Ruben; Engert, Florian

    2011-01-01

    In this study we report that larval zebrafish display adaptive locomotor output that can be driven by unexpected visual feedback. We develop a new assay that addresses visuomotor integration in restrained larval zebrafish. The assay involves a closed-loop environment in which the visual feedback a larva receives depends on its own motor output in a way that resembles freely swimming conditions. The experimenter can control the gain of this closed feedback loop, so that following a given motor output the larva experiences more or less visual feedback depending on whether the gain is high or low. We show that increases and decreases in this gain setting result in adaptive changes in behavior that lead to a generalized decrease or increase of motor output, respectively. Our behavioral analysis shows that both the duration and tail beat frequency of individual swim bouts can be modified, as well as the frequency with which bouts are elicited. These changes can be implemented rapidly, following an exposure to a new gain of just 175 ms. In addition, modifications in some behavioral parameters accumulate over tens of seconds and effects last for at least 30 s from trial to trial. These results suggest that larvae establish an internal representation of the visual feedback expected from a given motor output and that the behavioral modifications are driven by an error signal that arises from the discrepancy between this expectation and the actual visual feedback. The assay we develop presents a unique possibility for studying visuomotor integration using imaging techniques available in the larval zebrafish.

  15. Adaptive Locomotor Behavior in Larval Zebrafish

    PubMed Central

    Portugues, Ruben; Engert, Florian

    2011-01-01

    In this study we report that larval zebrafish display adaptive locomotor output that can be driven by unexpected visual feedback. We develop a new assay that addresses visuomotor integration in restrained larval zebrafish. The assay involves a closed-loop environment in which the visual feedback a larva receives depends on its own motor output in a way that resembles freely swimming conditions. The experimenter can control the gain of this closed feedback loop, so that following a given motor output the larva experiences more or less visual feedback depending on whether the gain is high or low. We show that increases and decreases in this gain setting result in adaptive changes in behavior that lead to a generalized decrease or increase of motor output, respectively. Our behavioral analysis shows that both the duration and tail beat frequency of individual swim bouts can be modified, as well as the frequency with which bouts are elicited. These changes can be implemented rapidly, following an exposure to a new gain of just 175 ms. In addition, modifications in some behavioral parameters accumulate over tens of seconds and effects last for at least 30 s from trial to trial. These results suggest that larvae establish an internal representation of the visual feedback expected from a given motor output and that the behavioral modifications are driven by an error signal that arises from the discrepancy between this expectation and the actual visual feedback. The assay we develop presents a unique possibility for studying visuomotor integration using imaging techniques available in the larval zebrafish. PMID:21909325

  16. Locomotor Experience Affects Self and Emotion

    ERIC Educational Resources Information Center

    Uchiyama, Ichiro; Anderson, David I.; Campos, Joseph J.; Witherington, David; Frankel, Carl B.; Lejeune, Laure; Barbu-Roth, Marianne

    2008-01-01

    Two studies investigated the role of locomotor experience on visual proprioception in 8-month-old infants. "Visual proprioception" refers to the sense of self-motion induced in a static person by patterns of optic flow. A moving room apparatus permitted displacement of an entire enclosure (except for the floor) or the side walls and…

  17. Predictive Measures of Locomotor Performance on an Unstable Walking Surface

    NASA Technical Reports Server (NTRS)

    Bloomberg, J. J.; Peters, B. T.; Mulavara, A. P.; Caldwell, E. E.; Batson, C. D.; De Dios, Y. E.; Gadd, N. E.; Goel, R.; Wood, S. J.; Cohen, H. S.; Oddsson, L. I.; Seidler, R. D.

    2016-01-01

    Locomotion requires integration of visual, vestibular, and somatosensory information to produce the appropriate motor output to control movement. The degree to which these sensory inputs are weighted and reorganized in discordant sensory environments varies by individual and may be predictive of the ability to adapt to novel environments. The goals of this project are to: 1) develop a set of predictive measures capable of identifying individual differences in sensorimotor adaptability, and 2) use this information to inform the design of training countermeasures designed to enhance the ability of astronauts to adapt to gravitational transitions improving balance and locomotor performance after a Mars landing and enhancing egress capability after a landing on Earth.

  18. Nicotine-induced perturbations on heart rate, body temperature and locomotor activity daily rhythms in rats.

    PubMed

    Pelissier, A L; Gantenbein, M; Bruguerolle, B

    1998-08-01

    The aim of this study was to evaluate the influence of nicotine on the daily rhythms of heart rate, body temperature and locomotor activity in unrestrained rats by use of implanted radiotelemetry transmitters. The study was divided into three seven-day periods: a control period, a treatment period and a recovery period. The control period was used for baseline measurement of heart rate, body temperature and locomotor activity. During the treatment period three rats received nicotine (1 mg kg(-1), s.c.) at 0900 h. Three rats received saline under the same experimental conditions. Heart rate, body temperature and locomotor activity were continuously monitored and plotted every 10 min. During the three periods a power spectrum analysis was used to determine the dominant period of rhythmicity. If daily rhythms of heart rate, body temperature and locomotor activity were detected, the characteristics of these rhythms, i.e. the mesors, amplitudes and acrophases, were determined by cosinor analysis, expressed as means +/- s.e.m. and compared by analysis of variance. Nicotine did not suppress daily rhythmicity but induced decreases of amplitudes and phase-advances of acrophases for heart rate, body temperature and locomotor activity. These perturbations might result from the effects of nicotine on the suprachiasmatic nucleus, the hypothalamic clock that co-ordinates biological rhythms.

  19. Circadian regulation of bird song, call, and locomotor behavior by pineal melatonin in the zebra finch.

    PubMed

    Wang, Gang; Harpole, Clifford E; Trivedi, Amit K; Cassone, Vincent M

    2012-04-01

    As both a photoreceptor and pacemaker in the avian circadian clock system, the pineal gland is crucial for maintaining and synchronizing overt circadian rhythms in processes such as locomotor activity and body temperature through its circadian secretion of the pineal hormone melatonin. In addition to receptor presence in circadian and visual system structures, high-affinity melatonin binding and receptor mRNA are present in the song control system of male oscine passeriform birds. The present study explores the role of pineal melatonin in circadian organization of singing and calling behavior in comparison to locomotor activity under different lighting conditions. Similar to locomotor activity, both singing and calling behavior were regulated on a circadian basis by the central clock system through pineal melatonin, since these behaviors free-ran with a circadian period and since pinealectomy abolished them in constant environmental conditions. Further, rhythmic melatonin administration restored their rhythmicity. However, the rates by which these behaviors became arrhythmic and the rates of their entrainment to rhythmic melatonin administration differed among locomotor activity, singing and calling under constant dim light and constant bright light. Overall, the study demonstrates a role for pineal melatonin in regulating circadian oscillations of avian vocalizations in addition to locomotor activity. It is suggested that these behaviors might be controlled by separable circadian clockworks and that pineal melatonin entrains them all through a circadian clock.

  20. Modelling spinal circuitry involved in locomotor pattern generation: insights from deletions during fictive locomotion

    PubMed Central

    Rybak, Ilya A; Shevtsova, Natalia A; Lafreniere-Roula, Myriam; McCrea, David A

    2006-01-01

    The mammalian spinal cord contains a locomotor central pattern generator (CPG) that can produce alternating rhythmic activity of flexor and extensor motoneurones in the absence of rhythmic input and proprioceptive feedback. During such fictive locomotor activity in decerebrate cats, spontaneous omissions of activity occur simultaneously in multiple agonist motoneurone pools for a number of cycles. During these ‘deletions’, antagonist motoneurone pools usually become tonically active but may also continue to be rhythmic. The rhythmic activity that re-emerges following a deletion is often not phase shifted. This suggests that some neuronal mechanism can maintain the locomotor period when motoneurone activity fails. To account for these observations, a simplified computational model of the spinal circuitry has been developed in which the locomotor CPG consists of two levels: a half-centre rhythm generator (RG) and a pattern formation (PF) network, with reciprocal inhibitory interactions between antagonist neural populations at each level. The model represents a network of interacting neural populations with single interneurones and motoneurones described in the Hodgkin-Huxley style. The model reproduces the range of locomotor periods and phase durations observed during real locomotion in adult cats and permits independent control of the level of motoneurone activity and of step cycle timing. By altering the excitability of neural populations within the PF network, the model can reproduce deletions in which motoneurone activity fails but the phase of locomotor oscillations is maintained. The model also suggests criteria for the functional identification of spinal interneurones involved in the mammalian locomotor pattern generation. PMID:17008376

  1. A potential flow based flight simulator for an underwater glider

    NASA Astrophysics Data System (ADS)

    Phoemsapthawee, Surasak; Le Boulluec, Marc; Laurens, Jean-Marc; Deniset, François

    2013-03-01

    Underwater gliders are recent innovative types of autonomous underwater vehicles (AUVs) used in ocean exploration and observation. They adjust their buoyancy to dive and to return to the ocean surface. During the change of altitude, they use the hydrodynamic forces developed by their wings to move forward. Their flights are controlled by changing the position of their centers of gravity and their buoyancy to adjust their trim and heel angles. For better flight control, the understanding of the hydrodynamic behavior and the flight mechanics of the underwater glider is necessary. A 6-DOF motion simulator is coupled with an unsteady potential flow model for this purpose. In some specific cases, the numerical study demonstrates that an inappropriate stabilizer dimension can cause counter-steering behavior. The simulator can be used to improve the automatic flight control. It can also be used for the hydrodynamic design optimization of the devices.

  2. Underwater wet welding of steel

    SciTech Connect

    Ibarra, S.; Liu, S.; Olson, D.L.

    1995-05-01

    Underwater wet welding is conducted directly in water with the shielded metal arc (SMA) and flux cored arc (FCA) welding processes. Underwater wet welding has been demonstrated as an acceptable repair technique down to 100 meters (325 ft.) in depth, but wet welds have been attempted on carbon steel structures down to 200 meters (650 ft.). The primary purpose of this interpretive report is to document and evaluate current understanding of metallurgical behavior of underwater wet welds so that new welding consumables can be designed and new welding practices can be developed for fabrication and repair of high strength steel structures at greater depths. First the pyrometallurgical and physical metallurgy behaviors of underwater weldments are discussed. Second, modifications of the welding consumables and processes are suggested to enhance the ability to apply wet welding techniques.

  3. Astronauts Practice Station Spacewalk Underwater

    NASA Video Gallery

    Astronauts Robert Satcher Jr. and Rick Sturckow conduct an underwater practice spacewalk session at Johnson Space Center’s Neutral Buoyancy Laboratory. The session was used to help International Sp...

  4. Underwater boom box

    NASA Astrophysics Data System (ADS)

    White, M. Catherine

    So far, there is no evidence that humpback whales are negatively affected by noise emitted from underwater speakers that may one day be used to measure warming in the oceans. A group of independent biologists from Cornell University monitored the behavior of the whales before, during, and after a scaled-down version of the controversial Acoustic Thermometry of Ocean Climate (ATOC) experiment off the coast of Hawaii. In 84 trials from February through March, they “saw no overt response from the whales.” Previous observations of similar sound transmissions at California's Pioneer Seamount, the other site planned for the experiment, also found no sign of disturbance among marine mammals, including elephant seals and several whale species. More observations are needed, however, before the experiment can be deemed safe, the Cornell biologists advised.

  5. Underwater Flow Noise

    NASA Astrophysics Data System (ADS)

    Dowling, A. P.

    Lighthill's theory of aerodynamic sound provides an effective way of investigating underwater flow noise. When combined with a model of the coherent vortical structures in a turbulent boundary layer, it predicts the wave-number frequency pressure spectrum on a rigid surface and, in particular, highlights the rôle of surface viscous stresses as a source of low wave-number pressure fluctuations on a plane surface. The inclusion of surface curvature and flexibility enables the theory to be applied to acoustic streamers (sometimes known as towed arrays). The effect of the interior mechanical structure of the streamers on the flow noise is investigated. Simple algebraic forms are derived for the comparative performance of liquid and visco-elastic-filled streamers. The introduction of porous foam into a liquid streamer is found to be a particularly effective way of attenuating low wave-number disturbances, and theoretical predictions are compared with experiment.

  6. Fish and chips: implementation of a neural network model into computer chips to maximize swimming efficiency in autonomous underwater vehicles.

    PubMed

    Blake, R W; Ng, H; Chan, K H S; Li, J

    2008-09-01

    Recent developments in the design and propulsion of biomimetic autonomous underwater vehicles (AUVs) have focused on boxfish as models (e.g. Deng and Avadhanula 2005 Biomimetic micro underwater vehicle with oscillating fin propulsion: system design and force measurement Proc. 2005 IEEE Int. Conf. Robot. Auto. (Barcelona, Spain) pp 3312-7). Whilst such vehicles have many potential advantages in operating in complex environments (e.g. high manoeuvrability and stability), limited battery life and payload capacity are likely functional disadvantages. Boxfish employ undulatory median and paired fins during routine swimming which are characterized by high hydromechanical Froude efficiencies (approximately 0.9) at low forward speeds. Current boxfish-inspired vehicles are propelled by a low aspect ratio, 'plate-like' caudal fin (ostraciiform tail) which can be shown to operate at a relatively low maximum Froude efficiency (approximately 0.5) and is mainly employed as a rudder for steering and in rapid swimming bouts (e.g. escape responses). Given this and the fact that bioinspired engineering designs are not obligated to wholly duplicate a biological model, computer chips were developed using a multilayer perception neural network model of undulatory fin propulsion in the knifefish Xenomystus nigri that would potentially allow an AUV to achieve high optimum values of propulsive efficiency at any given forward velocity, giving a minimum energy drain on the battery. We envisage that externally monitored information on flow velocity (sensory system) would be conveyed to the chips residing in the vehicle's control unit, which in turn would signal the locomotor unit to adopt kinematics (e.g. fin frequency, amplitude) associated with optimal propulsion efficiency. Power savings could protract vehicle operational life and/or provide more power to other functions (e.g. communications).

  7. Development of a Countermeasure to Mitigate Postflight Locomotor Dysfunction

    NASA Technical Reports Server (NTRS)

    Bloomberg, J. J.; Mulavara, A. P.; Peters, B. T.; Cohen, H. S.; Richards, J. T.; Miller, C. A.; Brady, R.; Warren, L. E.; Ruttley, T. M.

    2006-01-01

    Astronauts returning from space flight experience locomotor dysfunction following their return to Earth. Our laboratory is currently developing a gait adaptability training program that is designed to facilitate recovery of locomotor function following a return to a gravitational environment. The training program exploits the ability of the sensorimotor system to generalize from exposure to multiple adaptive challenges during training so that the gait control system essentially learns to learn and therefore can reorganize more rapidly when faced with a novel adaptive challenge. Evidence for the potential efficacy of an adaptive generalization gait training program can be obtained from numerous studies in the motor learning literature which have demonstrated that systematically varying the conditions of training enhances the ability of the performer to learn and retain a novel motor task. These variable practice training approaches have been used in applied contexts to improve motor skills required in a number of different sports. The central nervous system (CNS) can produce voluntary movement in an almost infinite number of ways. For example, locomotion can be achieved with many different combinations of joint angles, muscle activation patterns and forces. The CNS can exploit these degrees of freedom to enhance motor response adaptability during periods of adaptive flux like that encountered during a change in gravitational environment. Ultimately, the functional goal of an adaptive generalization countermeasure is not necessarily to immediately return movement patterns back to normal. Rather the training regimen should facilitate the reorganization of available sensory and motor subsystems to achieve safe and effective locomotion as soon as possible after long duration space flight. Indeed, this approach has been proposed as a basic feature underlying effective neurological rehabilitation. We have previously confirmed that subjects participating in an adaptive

  8. Locomotor Dysfunction after Spaceflight: Characterization and Countermeasure Development

    NASA Technical Reports Server (NTRS)

    Mulavara, A. P.; Cohen, H. S.; Peters, B. T.; Miller, C. A.; Brady, R.; Bloomberg, Jacob J.

    2007-01-01

    Astronauts returning from space flight show disturbances in locomotor control manifested by changes in various sub-systems including head-trunk coordination, dynamic visual acuity, lower limb muscle activation patterning and kinematics (Glasauer, et al., 1995; Bloomberg, et al., 1997; McDonald, et al., 1996; 1997; Layne, et al., 1997; 1998, 2001, 2004; Newman, et al., 1997; Bloomberg and Mulavara, 2003). These post flight changes in locomotor performance, due to neural adaptation to the microgravity conditions of space flight, affect the ability of crewmembers especially after a long duration mission to egress their vehicle and perform extravehicular activities soon after landing on Earth or following a landing on the surface of the Moon or Mars. At present, no operational training intervention is available pre- or in- flight to mitigate post flight locomotor disturbances. Our laboratory is currently developing a gait adaptability training program that is designed to facilitate recovery of locomotor function following a return to a gravitational environment. The training program exploits the ability of the sensorimotor system to generalize from exposure to multiple adaptive challenges during training so that the gait control system essentially "learns to learn" and therefore can reorganize more rapidly when faced with a novel adaptive challenge. Ultimately, the functional goal of an adaptive generalization countermeasure is not necessarily to immediately return movement patterns back to "normal". Rather the training regimen should facilitate the reorganization of available sensorimotor sub-systems to achieve safe and effective locomotion as soon as possible after space flight. We have previously confirmed that subjects participating in adaptive generalization training programs, using a variety of visuomotor distortions and different motor tasks from throwing to negotiating an obstacle course as the dependent measure, can learn to enhance their ability to adapt to a

  9. Pipeline inspection using an autonomous underwater vehicle

    SciTech Connect

    Egeskov, P.; Bech, M.; Bowley, R.; Aage, C.

    1995-12-31

    Pipeline inspection can be carried out by means of small Autonomous Underwater Vehicles (AUVs), operating either with a control link to a surface vessel, or totally independently. The AUV offers an attractive alternative to conventional inspection methods where Remotely Operated Vehicles (ROVs) or paravanes are used. A flatfish type AUV ``MARTIN`` (Marine Tool for Inspection) has been developed for this purpose. The paper describes the proposed types of inspection jobs to be carried out by ``MARTIN``. The design and construction of the vessel, its hydrodynamic properties, its propulsion and control systems are discussed. The pipeline tracking and survey systems, as well as the launch and recovery systems are described.

  10. Locomotor function in the early stage of Parkinson's disease.

    PubMed

    Carpinella, Ilaria; Crenna, Paolo; Calabrese, Elena; Rabuffetti, Marco; Mazzoleni, Paolo; Nemni, Raffaello; Ferrarin, Maurizio

    2007-12-01

    The cardinal motor symptoms of Parkinson's disease (PD) have been widely investigated with particular reference to abnormalities of steady-state walking. The great majority of studies, however are related to severe forms of PD patients (phases > = 3 of Hoehn and Yahr scale), where locomotor abnormalities are clearly manifested. Goal of the present study was to quantitatively describe locomotor symptoms in subjects with mild PD. Accordingly, a multitask protocol involving instrumental analysis of steady-state linear walking, initiation of gait, and turning while walking was applied to a group of patients with idiopathic PD in their early clinical stage (phases 1 and 2 of Hoehn and Yahr scale), as well as in age-matched elderly controls. Kinematic, kinetic, and myoelectric measures were obtained by optoelectronic motion analysis, force platform, and telemetric electromyography. Results in PD patients showed a tendency to bradykinetic gait, with reduction of walking speed and cadence. Impairments of gait initiation consisted in reduction of the backward shift of the center of pressure (CoP) and prolongation of the stepping phase. Alterations of the turning task were more consistent and included delayed reorientation of the head toward the new direction, altered head-upper trunk rotational strategy, and adoption of a greater number of steps to complete the turning. It is concluded that patients in the early stage of PD reveal mild alterations of steady-state linear walking and more significant anomalies in the transitional conditions, especially during changes in the travel direction. Quantitative analysis of nonstationary locomotor tasks might be a potentially useful starting point for further studies on the pathophysiology of PD.

  11. Effects of caffeine on locomotor activity in streptozotocin-induced diabetic rats.

    PubMed

    Bădescu, S V; Tătaru, C P; Kobylinska, L; Georgescu, E L; Zahiu, D M; Zăgrean, A M; Zăgrean, L

    2016-01-01

    Diabetes mellitus modifies the expression of adenosine receptors in the brain. Caffeine acts as an antagonist of A1 and A2A adenosine receptors and was shown to have a dose-dependent biphasic effect on locomotion in mice. The present study investigated the link between diabetes and locomotor activity in an animal model of streptozotocin-induced diabetes, and the effects of a low-medium dose of caffeine in this relation. The locomotor activity was investigated by using Open Field Test at 6 weeks after diabetes induction and after 2 more weeks of chronic caffeine administration. Diabetes decreased locomotor activity (total distance moved and mobility time). Chronic caffeine exposure impaired the locomotor activity in control rats, but not in diabetic rats. Our data suggested that the medium doses of caffeine might block the A2A receptors, shown to have an increased density in the brain of diabetic rats, and improve or at least maintain the locomotor activity, offering a neuroprotective support in diabetic rats. Abbreviations: STZ = streptozotocin, OFT = Open Field Test.

  12. Locomotor Muscle Fatigue Does Not Alter Oxygen Uptake Kinetics during High-Intensity Exercise

    PubMed Central

    Hopker, James G.; Caporaso, Giuseppe; Azzalin, Andrea; Carpenter, Roger; Marcora, Samuele M.

    2016-01-01

    The V˙O2 slow component (V˙O2sc) that develops during high-intensity aerobic exercise is thought to be strongly associated with locomotor muscle fatigue. We sought to experimentally test this hypothesis by pre-fatiguing the locomotor muscles used during subsequent high-intensity cycling exercise. Over two separate visits, eight healthy male participants were asked to either perform a non-metabolically stressful 100 intermittent drop-jumps protocol (pre-fatigue condition) or rest for 33 min (control condition) according to a random and counterbalanced order. Locomotor muscle fatigue was quantified with 6-s maximal sprints at a fixed pedaling cadence of 90 rev·min−1. Oxygen kinetics and other responses (heart rate, capillary blood lactate concentration and rating of perceived exertion, RPE) were measured during two subsequent bouts of 6 min cycling exercise at 50% of the delta between the lactate threshold and V˙O2max determined during a preliminary incremental exercise test. All tests were performed on the same cycle ergometer. Despite significant locomotor muscle fatigue (P = 0.03), the V˙O2sc was not significantly different between the pre-fatigue (464 ± 301 mL·min−1) and the control (556 ± 223 mL·min−1) condition (P = 0.50). Blood lactate response was not significantly different between conditions (P = 0.48) but RPE was significantly higher following the pre-fatiguing exercise protocol compared with the control condition (P < 0.01) suggesting higher muscle recruitment. These results demonstrate experimentally that locomotor muscle fatigue does not significantly alter the V˙O2 kinetic response to high intensity aerobic exercise, and challenge the hypothesis that the V˙O2sc is strongly associated with locomotor muscle fatigue. PMID:27790156

  13. Effects of repeated blood samplings on locomotor activity, evasion and wheel-running activity in mice.

    PubMed

    Pfeil, R

    1988-01-01

    The effects of serial blood sampling on nocturnal locomotor activity, evasion, wheel-running activity and body mass were studied in male NMRI mice aged 7-8 weeks. The erythrocyte count, haematocrit and haemoglobin concentration at the beginning and end of the study showed no difference in group 1 (two samples per week, 0.08 ml each) while there was a significant decrease in the group 2 values (three samples per week, 0.08 ml each). The total amount of nocturnal locomotor activity decreased in the animals bled repeatedly while the periods with locomotor activity increased. These alterations appeared particularly after bleeding. In the test-group animals evasion showed a decrease compared with the untreated control animals, but there was no evidence of a relation to the timing of the bleedings.

  14. Locomotor activity and tissue levels following acute ...

    EPA Pesticide Factsheets

    Pyrethroids produce neurotoxicity that depends, in part, on the chemical structure. Common behavioral effects include locomotor activity changes and specific toxic syndromes (types I and II). In general these neurobehavioral effects correlate well with peak internal dose metrics. Products of cyhalothrin, a type II pyrethroid, include mixtures of isomers (e.g., λ-cyhalothrin) as well as enriched active isomers (e.g., γ-cyhalothrin). We measured acute changes in locomotor activity in adult male rats and directly correlated these changes to peak brain and plasma concentrations of λ- and γ-cyhalothrin using a within-subject design. One-hour locomotor activity studies were conducted 1.5 h after oral gavage dosing, and immediately thereafter plasma and brains were collected for analyzing tissue levels using LC/MS/MS methods. Both isomers produced dose-related decreases in activity counts, and the effective dose range for γ-cyhalothrin was lower than for λ-cyhalothrin. Doses calculated to decrease activity by 50% were 2-fold lower for the γ-isomer (1.29 mg/kg) compared to λ-cyhalothrin (2.65 mg/kg). Salivation, typical of type II pyrethroids, was also observed at lower doses of γ-cyhalothrin. Administered dose correlated well with brain and plasma concentrations, which furthermore showed good correlations with activity changes. Brain and plasma levels were tightly correlated across doses. While γ-cyhalothrin was 2-fold more potent based on administ

  15. Effect of physical exercise prelabyrinthectomy on locomotor balance compensation in the squirrel monkey

    NASA Technical Reports Server (NTRS)

    Igarashi, M.; Ohashi, K.; Yoshihara, T.; MacDonald, S.

    1989-01-01

    This study examines the effectiveness of physical exercise, during a prepathology state, on locomotor balance compensation after subsequent unilateral labyrinthectomy in squirrel monkeys. An experimental group underwent 3 hr. of daily running exercise on a treadmill for 3 mo. prior to the surgery, whereas a control group was not exercised. Postoperatively, the locomotor balance function of both groups was tested for 3 mo. There was no significant difference in gait deviation counts in the acute phase of compensation. However, in the chronic compensation maintenance phase, the number of gait deviation counts was fewer in the exercise group, which showed significantly better performance stability.

  16. Underwater Shock Wave Research Applied to Therapeutic Device Developments

    NASA Astrophysics Data System (ADS)

    Takayama, K.; Yamamoto, H.; Shimokawa, H.

    2013-07-01

    The chronological development of underwater shock wave research performed at the Shock Wave Research Center of the Institute of Fluid Science at the Tohoku University is presented. Firstly, the generation of planar underwater shock waves in shock tubes and their visualization by using the conventional shadowgraph and schlieren methods are described. Secondly, the generation of spherical underwater shock waves by exploding lead azide pellets weighing from several tens of micrograms to 100 mg, that were ignited by irradiating with a Q-switched laser beam, and their visualization by using double exposure holographic interferometry are presented. The initiation, propagation, reflection, focusing of underwater shock waves, and their interaction with various interfaces, in particular, with air bubbles, are visualized quantitatively. Based on such a fundamental underwater shock wave research, collaboration with the School of Medicine at the Tohoku University was started for developing a shock wave assisted therapeutic device, which was named an extracorporeal shock wave lithotripter (ESWL). Miniature shock waves created by irradiation with Q-switched HO:YAG laser beams are studied, as applied to damaged dysfunctional nerve cells in the myocardium in a precisely controlled manner, and are effectively used to design a catheter for treating arrhythmia.

  17. Age-Related Differences in Locomotor Strategies During Adaptive Walking.

    PubMed

    Lowry, Kristin A; Sebastian, Katherine; Perera, Subashan; Van Swearingen, Jessie; Smiley-Oyen, Ann L

    2016-11-21

    Simultaneous control of lower limb stepping movements and trunk motion is important for skilled walking; adapting gait to environmental constraints requires frequent alternations in stepping and trunk motion. These alterations provide a window into the locomotor strategies adopted by the walker. The authors examined gait strategies in young and healthy older adults when manipulating step width. Anteroposterior (AP) and mediolateral (ML) smoothness (quantified by harmonic ratios) and stepping consistency (quantified by gait variability) were analyzed during narrow and wide walking while controlling cadence to preferred pace. Results indicated older adults preserved ML smoothness at the expense of AP smoothness, shortened their steps, and exhibited reduced stepping consistency. The authors conclude that older adults prioritized ML control over forward progression during adaptive walking challenges.

  18. The Effect of Underwater Gait Training on Balance Ability of Stroke Patients

    PubMed Central

    Park, Seok Woo; Lee, Kyoung Jin; Shin, Doo Chul; Shin, Seung Ho; Lee, Myung Mo; Song, Chang Ho

    2014-01-01

    [Purpose] The purpose of this study was to investigate the effects of underwater treadmill gait training on the balance ability of stroke patients. [Subjects] Twenty-two patients with stroke were randomly assigned to an underwater treadmill group (n =11) or a control group (n =11). [Methods] Both groups received general rehabilitation for 30 min per session, 5 times per week, over a 4-week period. The underwater treadmill group received additional underwater gait training for 30 min per session, 5 times per week, over the same 4-week period. Static and dynamic balances were evaluated before and after the intervention. [Results] The means of static and dynamic balance ability increased significantly in both groups, but there was no significant difference between the two groups. [Conclusion] Compared to the general rehabilitation program, underwater treadmill gait training was not more effective at improving the balance ability of stroke patients than land-based training. PMID:25013292

  19. Covert underwater acoustic communications.

    PubMed

    Ling, Jun; He, Hao; Li, Jian; Roberts, William; Stoica, Petre

    2010-11-01

    Low probability of detection (LPD) communications are conducted at a low received signal-to-noise ratio (SNR) to deter eavesdroppers to sense the presence of the transmitted signal. Successful detection at intended receiver heavily relies on the processing gain achieved by employing the direct-sequence spread-spectrum (DSSS) technique. For scenarios that lack a sufficiently low SNR to maintain LPD, another metric, referred to as low probability of interception (LPI), is of interest to protect the privacy of the transmitted information. If covert communications take place in underwater acoustic (UWA) environments, then additional challenges are present. The time-varying nature of the UWA channel prevents the employment of a long spreading waveform. Furthermore, UWA environments are frequency-selective channels with long memory, which imposes challenges to the design of the spreading waveform. In this paper, a covert UWA communication system that adopts the DSSS technique and a coherent RAKE receiver is investigated. Emphasis is placed on the design of a spreading waveform that not only accounts for the transceiver structure and frequency-selective nature of the UWA channel, but also possesses a superior LPI. The proposed techniques are evaluated using both simulated and SPACE'08 in-water experimental data.

  20. Underwater loudness for tones

    NASA Astrophysics Data System (ADS)

    Cudahy, Edward A.; Schwaller, Derek

    2002-05-01

    The loudness for pure tones was measured by loudness matching for 1-s pure tones from 100 to 50000 Hz. The standard tone was 1000 Hz. Subjects were instructed to match the loudness of the comparison tone at one of the test frequencies to the loudness of the standard tone. The standard was presented at one of five sound pressure levels (SPL) for each set of frequencies. The SPL was varied randomly across a test series. The subjects were bareheaded U.S. Navy divers tested at a depth of 3 m. All subjects had normal hearing. The tones were presented to the right side of the subject from an array of underwater sound projectors. The SPL was calibrated at the location of the subject's head with the subject absent. The loudness increased more rapidly as a function of standard SPL at mid-frequencies than at either high or low frequencies. The most compact loudness contours (the least SPL change across the range of standard SPL) were at the highest frequency. Loudness contours across frequency derived from these measurements are significantly different from in-air measurements with minimum audibility in the 1000 Hz region rather than the 2-4 kHz region observed for in-air measurements.

  1. Voluntary and reactive recruitment of locomotor muscle synergies during perturbed walking.

    PubMed

    Chvatal, Stacie A; Ting, Lena H

    2012-08-29

    The modular control of muscles in groups, often referred to as muscle synergies, has been proposed to provide a motor repertoire of actions for the robust control of movement. However, it is not clear whether muscle synergies identified in one task are also recruited by different neural pathways subserving other motor behaviors. We tested the hypothesis that voluntary and reactive modifications to walking in humans result from the recruitment of locomotor muscle synergies. We recorded the activity of 16 muscles in the right leg as subjects walked a 7.5 m path at two different speeds. To elicit a second motor behavior, midway through the path we imposed ramp and hold translation perturbations of the support surface in each of four cardinal directions. Variations in the temporal recruitment of locomotor muscle synergies could account for cycle-by-cycle variations in muscle activity across strides. Locomotor muscle synergies were also recruited in atypical phases of gait, accounting for both anticipatory gait modifications before perturbations and reactive feedback responses to perturbations. Our findings are consistent with the idea that a common pool of spatially fixed locomotor muscle synergies can be recruited by different neural pathways, including the central pattern generator for walking, brainstem pathways for balance control, and cortical pathways mediating voluntary gait modifications. Together with electrophysiological studies, our work suggests that muscle synergies may provide a library of motor subtasks that can be flexibly recruited by parallel descending pathways to generate a variety of complex natural movements in the upper and lower limbs.

  2. Yawning and locomotor behavior induced by dopamine receptor agonists in mice and rats.

    PubMed

    Li, Su-Min; Collins, Gregory T; Paul, Noel M; Grundt, Peter; Newman, Amy H; Xu, Ming; Grandy, David K; Woods, James H; Katz, Jonathan L

    2010-05-01

    Dopaminergic (DA) agonist-induced yawning in rats seems to be mediated by DA D3 receptors, and low doses of several DA agonists decrease locomotor activity, an effect attributed to presynaptic D2 receptors. Effects of several DA agonists on yawning and locomotor activity were examined in rats and mice. Yawning was reliably produced in rats, and by the cholinergic agonist, physostigmine, in both the species. However, DA agonists were ineffective in producing yawning in Swiss-Webster or DA D2R and DA D3R knockout or wild-type mice. The drugs significantly decreased locomotor activity in rats at one or two low doses, with activity returning to control levels at higher doses. In mice, the drugs decreased locomotion across a 1000-10 000-fold range of doses, with activity at control levels (U-91356A) or above control levels [(+/-)-7-hydroxy-2-dipropylaminotetralin HBr, quinpirole] at the highest doses. Low doses of agonists decreased locomotion in all mice except the DA D2R knockout mice, but were not antagonized by DA D2R or D3R antagonists (L-741 626, BP 897, or PG01037). Yawning does not provide a selective in-vivo indicator of DA D3R agonist activity in mice. Decreases in mouse locomotor activity by the DA agonists seem to be mediated by D2 DA receptors.

  3. Underwater measurements of muon intensity

    NASA Technical Reports Server (NTRS)

    Fedorov, V. M.; Pustovetov, V. P.; Trubkin, Y. A.; Kirilenkov, A. V.

    1985-01-01

    Experimental measurements of cosmic ray muon intensity deep underwater aimed at determining a muon absorption curve are of considerable interest, as they allow to reproduce independently the muon energy spectrum at sea level. The comparison of the muon absorption curve in sea water with that in rock makes it possible to determine muon energy losses caused by nuclear interactions. The data available on muon absorption in water and that in rock are not equivalent. Underground measurements are numerous and have been carried out down to the depth of approx. 15km w.e., whereas underwater muon intensity have been measured twice and only down to approx. 3km deep.

  4. Underwater laser imaging system (UWLIS)

    SciTech Connect

    DeLong, M.

    1994-11-15

    Practical limitations with underwater imaging systems area reached when the noise in the back scattered radiation generated in the water between the imaging system and the target obscures the spatial contrast and resolution necessary for target discovery and identification. The advent of high power lasers operating in the blue-green portion of the visible spectrum (oceanic transmission window) has led to improved experimental illumination systems for underwater imaging. Range-gated and synchronously scanned devices take advantage of the unique temporal and spatial coherence properties of laser radiation, respectively, to overcome the deleterious effects of common volume back scatter.

  5. Modelling the locomotor energetics of extinct hominids.

    PubMed

    Kramer, P A

    1999-10-01

    Bipedality is the defining characteristic of Hominidae and, as such, an understanding of the adaptive significance and functional implications of bipedality is imperative to any study of human evolution. Hominid bipedality is, presumably, a solution to some problem for the early hominids, one that has much to do with energy expenditure. Until recently, however, little attention could be focused on the quantifiable energetic aspects of bipedality as a unique locomotor form within Primates because of the inability to measure empirically the energy expenditure of non-modern hominids. A recently published method provides a way of circumventing the empirical measurement dilemma by calculating energy expenditure directly from anatomical variables and movement profiles. Although the origins of bipedality remain clouded, two discernible forms of locomotor anatomy are present in the hominid fossil record: the australopithecine and modern configurations. The australopithecine form is best represented by AL 288-1, a partial skeleton of Australopithecus afarensis, and is characterized as having short legs and a wide pelvis. The modern form is represented by modern humans and has long legs and a narrow pelvis. Human walking is optimized to take advantage of the changing levels of potential and kinetic energy that occur as the body and limbs move through the stride cycle. Although this optimization minimizes energy expenditure, some energy is required to maintain motion. I quantify this energy by developing a dynamic model that uses kinematic equations to determine energy expenditure. By representing both configurations with such a model, I can compare their rates of energy expenditure. I find that the australopithecine configuration uses less energy than that of a modern human. Despite arguments presented in the anthropological literature, the shortness of the legs of AL 288-1 provides no evidence that she was burdened with a compromised or transitional locomotor anatomy

  6. The hyperactive syndrome: metanalysis of genetic alterations, pharmacological treatments and brain lesions which increase locomotor activity.

    PubMed

    Viggiano, Davide

    2008-12-01

    synthesis usually results in hypoactive behaviour. However, a chronic increase in norepinephrine may result in hypoactivity too. Similarly, changes in both directions of serotonin levels may reduce locomotor activity, whereas alterations in specific serotonin receptors can induce hyperactivity. The lesion of at least 12 different brain regions can increase locomotor activity too. Comparatively, few focal lesions decrease locomotor activity. Finally, a large number of toxic events can increase locomotor activity, particularly if delivered during the prepuberal time window. These data show that there is a net imbalance in the number of altered genes/brain lesions/toxics that induce hyperactivity versus hypoactive behaviour. Although some of these data may be explained in terms of the activating role of subcortical systems (such as catecholamines), the larger number of alterations that induce hyperactivity suggests a different scenario. Specifically, we hypothesize (i) the existence of a control system that continuously inhibit a basally hyperactive locomotor tone and (ii) that this control system is highly vulnerable (intrinsic fragility) to any change in the genetic asset or to any toxic/drug delivered during prepuberal stages. Brain lesion studies suggest that the putative control system is located along an axis that connects the olfactory bulb and the enthorhinal cortex (enthorhinal-hippocampal-septal-prefrontal cortex-olfactory bulb axis). We suggest that the increased locomotor activity in many psychiatric diseases may derive from the interference with the development of this brain axis during a specific postnatal time window.

  7. Locomotor activity and body temperature in selected mouse lines differing greatly in feed intake.

    PubMed

    Sojka, P A; Griess, R S; Nielsen, M K

    2013-08-01

    Locomotor activity, body temperature, feed intake, and BW were measured on 382 mature male mice sampled from lines previously selected (25 generations) for either high (MH) or low (ML) heat loss and an unselected control (MC). Animals were from all 3 independent replicates of the 3 lines and across 4 generations (68 through 71). Locomotor activity and body temperatures were obtained using implanted transmitters with data collection over 4 d following a 3-d postsurgery recovery period. Data were collected every minute and then averaged into 30-min periods, thus providing 192 data points for each mouse. Least-squares means for feed intake adjusted for BW (Feed/BW, feed·BW(-1)·d(-1), g/g) were 0.1586, 0.1234, and 0.1125 (±0.0022) for MH, MC, and ML, respectively, with line being a highly significant source of variation (P < 0.0003). Line effects for locomotor activity counts, transformed to the 0.25 power for analysis, were significantly different, with MH mice being 2.1 times more active than ML mice (P < 0.003); MC mice were intermediate. Differences in body temperature were significant for both line (P < 0.03) and day effects (P < 0.001), with a 0.32°C difference between the MH and ML lines. Fourier series analysis used the combined significant periodicities of 24, 18, 12, 9, 6, and 3 h to describe circadian cycles for activity and body temperature. All 3 lines expressed daily peaks in body temperature and locomotor activity ∼3 h into darkness and ∼2 h after lights were turned on. There was a stronger relationship between locomotor activity and Feed/BW (P < 0.0001) than between body temperature and Feed/BW (P < 0.01); differences between lines in locomotor activity and body temperature explained 17% and 3%, respectively, of differences between lines in Feed/BW. Thus, line differences in locomotor activity contribute to line differences in maintenance, but approximately 80% of the differences between the MH and ML selection lines in Feed/BW remains

  8. Effect of Environmental Conditions and Toxic Compounds on the Locomotor Activity of Pediculus humanus capitis (Phthiraptera: Pediculidae).

    PubMed

    Ortega-Insaurralde, I; Toloza, A C; Gonzalez-Audino, P; Mougabure-Cueto, G A; Alvarez-Costa, A; Roca-Acevedo, G; Picollo, M I

    2015-09-01

    In this work, we evaluated the effect of environmental variables such as temperature, humidity, and light on the locomotor activity of Pediculus humanus capitis. In addition, we used selected conditions of temperature, humidity, and light to study the effects of cypermethrin and N,N-diethyl-3-methylbenzamide (DEET) on the locomotor activity of head lice. Head lice increased their locomotor activity in an arena at 30°C compared with activity at 20°C. When we tested the influence of the humidity level, the locomotor activity of head lice showed no significant differences related to humidity level, both at 30°C and 20°C. Concerning light influence, we observed that the higher the intensity of light, the slower the movement of head lice. We also demonstrated that sublethal doses of toxics may alter locomotor activity in adults of head lice. Sublethal doses of cypermethrin induced hyperactivated responses in adult head lice. Sublethal doses of DEET evocated hypoactivated responses in head lice. The observation of stereotyped behavior in head lice elicited by toxic compounds proved that measuring locomotor activity in an experimental set-up where environmental conditions are controlled would be appropriate to evaluate compounds of biological importance, such as molecules involved in the host-parasite interaction and intraspecific relationships.

  9. Compressive line sensing underwater imaging system

    NASA Astrophysics Data System (ADS)

    Ouyang, Bing; Dalgleish, Fraser R.; Caimi, Frank M.; Giddings, Thomas E.; Britton, Walter; Vuorenkoski, Anni K.; Nootz, Gero

    2014-05-01

    Compressive sensing (CS) theory has drawn great interest and led to new imaging techniques in many different fields. Over the last few years, the authors have conducted extensive research on CS-based active electro-optical imaging in a scattering medium, such as the underwater environment. This paper proposes a compressive line sensing underwater imaging system that is more compatible with conventional underwater survey operations. This new imaging system builds on our frame-based CS underwater laser imager concept, which is more advantageous for hover capable platforms. We contrast features of CS underwater imaging with those of traditional underwater electro-optical imaging and highlight some advantages of the CS approach. Simulation and initial underwater validation test results are also presented.

  10. Visual training improves underwater vision in children.

    PubMed

    Gislén, Anna; Warrant, Eric J; Dacke, Marie; Kröger, Ronald H H

    2006-10-01

    Children in a tribe of sea-gypsies from South-East Asia have been found to have superior underwater vision compared to European children. In this study, we show that the improved underwater vision of these Moken children is not due to better contrast sensitivity in general. We also show that European children can achieve the same underwater acuity as the Moken children. After 1 month of underwater training (11 sessions) followed by 4 months with no underwater activities, European children showed improved underwater vision and distinct bursts of pupil constriction. When tested 8 months after the last training session in an outdoor pool in bright sunlight-comparable to light environments in South-East Asia-the children had attained the same underwater acuity as the sea-gypsy children. The achieved performance can be explained by the combined effect of pupil constriction and strong accommodation.

  11. On the efficient swimming of a ray-inspired underwater vehicle Part I: Experimental study on swimming optimization of control and fin structure

    NASA Astrophysics Data System (ADS)

    Zhu, Jianzhong; Lopez, Mervyn; Williams, Ventress; Aluko, Theophilus; Dong, Haibo; Bart-Smith, Hilary

    2014-11-01

    Batoid fish such as manta and cownose rays are among the most agile and energy efficient swimming creatures. These capabilities arise from flapping and bending their dorsally flattened pectoral fins. To assess this contribution, this study focuses on the study of a bio-inspired underwater vehicle--the MantaBot--where biological design criteria are applied. The MantaBot consists of two parts: a rigid body rendered from a CT scanning image of a cownose ray and two flexible fins driven by tensegrity actuators. The experiments were conducted in a water tank where the MantaBot was attached to a rail for rectilinear swimming. Three stereo-videos were taken and digitized to measure the 3D kinematics. Results showed that the fins conduct deformations in both spanwise and chordwise directions during steady swimming. Optimal operation conditions were determined for fastest swimming by surveying a wide range of parameters. Contributions of thrust generation and amplitude hindrance of various portions of the fin volume were examined. Additionally, fin tip structure, material and bending properties were studied for optimal swimming. This research was supported by the Office of Naval Research (ONR) under the Multidisciplinary University Research Initiative (MURI) Grant N00014-08-1-0642 and Grant N00014-14-1-0533.

  12. Underwater Robots Surface in Utah

    ERIC Educational Resources Information Center

    Hurd, Randy C.; Hacking, Kip S.; Damarjian, Jennifer L.; Wright, Geoffrey A.; Truscott, Tadd

    2015-01-01

    Underwater robots (or ROVs: Remotely Operated Vehicles as they are typically called in industry) have recently become a very popular instructional STEM activity. Nationally, ROVs have been used in science and technology classrooms for several years in cities such as Seattle, San Diego, Virginia Beach, and other coastal areas. In the past two…

  13. Underwater cold tap machine tested

    SciTech Connect

    Not Available

    1985-05-01

    Tests are complete on a strategic cold tap machine for underwater lines. The system was designed around Total's Norway-UK Frigg gas line. It provides a permanent, easily mobilized, mechanical insurance against damage to the Frigg line but also provides a proven, workable principle for the repair or modification of other lines. The design of the system is discussed.

  14. Adaptive Reception for Underwater Communications

    DTIC Science & Technology

    2011-06-01

    Multipath effect on a sinusoidal pulse ................................................. 23 Figure 6. Examples of frequency non-selective/selective fading...Basis Function RLS Recursive Least Squares SIMO Single Input Multiple Output SINR Signal to Interference and Noise Ratio SISO Single Input Single...Output SNR Signal to Noise Ratio SVD Singular Value Decomposition TL Transmission Loss UUV Unmanned Underwater Vehicle WHOI Woods Hole

  15. Underwater Multimode Directional Transducer Evaluation

    DTIC Science & Technology

    2003-12-01

    The work described in the present thesis is intended to establish a procedure for analyzing directional transducers for future underwater wireless...networks, as well as to carry out the performance evaluation of a multimode transducer prototype with respect to its main operational requirements

  16. Remote Underwater Characterization System - Innovative Technology Summary Report

    SciTech Connect

    Willis, W D

    1999-04-01

    Characterization and inspection of water-cooled and moderated nuclear reactors and fuel storage pools requires equipment capable of operating underwater. Similarly, the deactivation and decommissioning of older nuclear facilities often requires the facility owner to accurately characterize underwater structures and equipment which may have been sitting idle for years. The Remote Underwater Characterization System (RUCS) is a small, remotely operated submersible vehicle intended to serve multiple purposes in underwater nuclear operations. It is based on the commercially-available "Scallop" vehicle 1 , but has been modified by the Department of Energy's Robotics Technology Development Program to add auto-depth control, and vehicle orientation and depth monitoring at the operator control panel. The RUCS is designed to provide visual and gamma radiation characterization, even in confined or limited access areas. It was demonstrated in August 1998 at the Idaho National Engineering and Environmental Laboratory (INEEL) as part of the INEEL Large Scale Demonstration and Deployment Project. During the demonstration it was compared in a "head-to-head" fashion with the baseline characterization technology. This paper summarizes the results of the demonstration and lessons learned; comparing and contrasting both technologies in the areas of cost, visual characterization, radiological characterization, and overall operations.

  17. Melatonin and locomotor activity in the fiddler crab Uca pugilator.

    PubMed

    Tilden, Andrea R; Shanahan, J Kearney; Khilji, Zahra S; Owen, Jeffrey G; Sterio, Thomas W; Thurston, Kristy T

    2003-05-01

    The influence of melatonin on locomotor activity levels was measured in the fiddler crab Uca pugilator. First, activity in untreated, laboratory-acclimated crabs was measured over 48 hours in a 12L:12D photoperiod; this study showed a nocturnal increase in activity. In eyestalk-ablated crabs, overall activity was significantly reduced, and no significant activity pattern occurred. Next, crabs were injected with melatonin or saline (controls) at various times during the 12L:12D photoperiod (0900h, 1200h, and twice at 2100h; each trial was separated by 3-4 days) and monitored for 3 hr post-injection. Control crabs had low activity during early photophase, high at mid-photophase, increasing activity during the first scotophase trial, and decreasing activity during the second scotophase trial. Melatonin had no significant influence on activity when injected during the early-photophase activity trough or early-scotophase activity decline, but significantly increased activity when injected during the mid-photophase activity peak and early-scotophase activity incline. Next, crabs were injected during an early scotophase activity trough and monitored throughout the twelve-hour scotophase. Melatonin did not increase activity until the mid-scotophase activity increase, approximately 6 hours later, showing that the pharmacological dosage persisted in the crabs' systems and had later effects during the incline and peak of activity but not the trough. Eyestalk-ablated crabs were injected with melatonin or saline during early photo- and scotophase. Melatonin significantly increased activity in the photophase but not the scotophase trial, indicating that the responsiveness to melatonin continues following eyestalk removal, but the timing may not match that of intact crabs. Melatonin may be involved in the transmission of environmental timing information from the eyestalks to locomotor centers in U. pugilator.

  18. METHAMPHETAMINE TREATMENT CAUSES DELAYED DECREASE IN NOVELTY-INDUCED LOCOMOTOR ACTIVITY IN MICE

    PubMed Central

    Krasnova, Irina N.; Hodges, Amber B.; Ladenheim, Bruce; Rhoades, Raina; Phillip, Crystal G.; Ceseňa, Angela; Ivanova, Ekaterina; Hohmann, Christine F.; Cadet, Jean Lud

    2009-01-01

    Methamphetamine (METH) is a psychostimulant that causes damage to dopamine (DA) axons and to non-monoaminergic neurons in the brain. The aim of the present study was to investigate short- and long-term effects of neurotoxic METH treatment on novelty-induced locomotor activity in mice. Male BALB/c mice, 12–14 weeks old, were injected with saline or METH (i.p., 7.5 mg/kg × 4 times, every 2 hours). Behavior and neurotoxic effects were assessed at 10 days, 3 and 5 months following drug treatment. METH administration caused marked decreases in DA levels in the mouse striatum and cortex at 10 days post-drug. However, METH did not induce any changes in novelty-induced locomotor activity. At 3 and 5 months after treatment METH-exposed mice showed significant recovery of DA levels in the striatum and cortex. In contrast, these animals demonstrated significant decreases in locomotor activity at 5 months in comparison to aged-matched control mice. Further assessment of METH toxicity using TUNEL staining showed that the drug induced increased cell death in the striatum and cortex at 3 days after administration. Taken together, these data suggest that delayed deficits in novelty-induced locomotor activity observed in METH exposed animals are not due to neurodegeneration of DA terminals but to combined effects of METH and age-dependent dysfunction of non-DA intrinsic striatal and/or corticostriatal neurons. PMID:19559060

  19. The GABAB agonist baclofen blocks the expression of sensitisation to the locomotor stimulant effect of amphetamine.

    PubMed

    Bartoletti, M; Gubellini, C; Ricci, F; Gaiardi, M

    2004-09-01

    The purpose of the present study was to test the possible influence of baclofen, a GABAB agonist, on the long-term sensitisation to amphetamine in rats. As expected, chronic amphetamine treatment (1.5 mg/kg i.p. daily for 10 days) led to an increased locomotor response to amphetamine (0.75 mg/kg i.p.), when the animals were challenged 20 days after the end of repeated treatment. Baclofen (2 mg/kg i.p.), administered before the test session, did not significantly modify the spontaneous locomotor activity of rats, but decreased the normal and, to a greater extent, the sensitised locomotor response to amphetamine; thus baclofen prevented the expression of sensitisation to amphetamine. Moreover a previous chronic treatment with baclofen (2 mg/kg i.p. daily for 10 days) attenuated the amphetamine-induced locomotor activity in sensitised, but not in control animals. This effect was observed 20 days after the last baclofen administration. In conclusion, the present results demonstrate that GABAB receptors play an important role in the expression of the sensitised behavioural response to amphetamine and further support a potential role of GABAB agonists in the treatment of psychostimulant addiction.

  20. Dissociation of locomotor and cerebellar deficits in a murine Angelman syndrome model

    PubMed Central

    Bruinsma, Caroline F.; Schonewille, Martijn; Gao, Zhenyu; Aronica, Eleonora M.A.; Judson, Matthew C.; Philpot, Benjamin D.; Hoebeek, Freek E.; van Woerden, Geeske M.; De Zeeuw, Chris I.; Elgersma, Ype

    2015-01-01

    Angelman syndrome (AS) is a severe neurological disorder that is associated with prominent movement and balance impairments that are widely considered to be due to defects of cerebellar origin. Here, using the cerebellar-specific vestibulo-ocular reflex (VOR) paradigm, we determined that cerebellar function is only mildly impaired in the Ube3am–/p+ mouse model of AS. VOR phase-reversal learning was singularly impaired in these animals and correlated with reduced tonic inhibition between Golgi cells and granule cells. Purkinje cell physiology, in contrast, was normal in AS mice as shown by synaptic plasticity and spontaneous firing properties that resembled those of controls. Accordingly, neither VOR phase-reversal learning nor locomotion was impaired following selective deletion of Ube3a in Purkinje cells. However, genetic normalization of αCaMKII inhibitory phosphorylation fully rescued locomotor deficits despite failing to improve cerebellar learning in AS mice, suggesting extracerebellar circuit involvement in locomotor learning. We confirmed this hypothesis through cerebellum-specific reinstatement of Ube3a, which ameliorated cerebellar learning deficits but did not rescue locomotor deficits. This double dissociation of locomotion and cerebellar phenotypes strongly suggests that the locomotor deficits of AS mice do not arise from impaired cerebellar cortex function. Our results provide important insights into the etiology of the motor deficits associated with AS. PMID:26485287

  1. Locomotor tests predict community mobility in children and youth with cerebral palsy.

    PubMed

    Ferland, Chantale; Moffet, Hélène; Maltais, Désirée B

    2012-07-01

    Ambulatory children and youth with cerebral palsy have limitations in locomotor capacities and in community mobility. The ability of three locomotor tests to predict community mobility in this population (N = 49, 27 boys, 6-16 years old) was examined. The tests were a level ground walking test, the 6-min-Walk-Test (6MWT), and two tests of advanced locomotor capacities, the 10-meter-Shuttle-Run-Test (10mSRT) and the Timed-Up-and-Down-Stairs-Test (TUDS). Community mobility was measured with the Assessment of Life Habits mobility category. After age and height were controlled, regression analysis identified 10mSRT and TUDS values as significant predictors of community mobility. They explained about 40% of the variance in the Life Habits mobility category scores. The 10mSRT was the strongest predictor (standardized Beta coefficient = 0.48, p = 0.002). The 6MWT was not a significant predictor. Thus, advanced locomotor capacity tests may be better predictors of community mobility in this population than level ground walking tests.

  2. Fabrication of Long-Term Underwater Superoleophobic Al Surfaces and Application on Underwater Lossless Manipulation of Non-Polar Organic Liquids

    PubMed Central

    Song, Jinlong; Huang, Liu; Lu, Yao; Liu, Xin; Deng, Xu; Yang, Xiaolong; Huang, Shuai; Sun, Jing; Jin, Zhuji; Parkin, Ivan P.

    2016-01-01

    Underwater superoleophobic surfaces have different applications in fields from oil/water separation to underwater lossless manipulation. This kind of surfaces can be easily transformed from superhydrophilic surfaces in air, which means the stability of superhydrophilicity in air determines the stability of underwater superoleophobicity. However, superhydrophilic surfaces fabricated by some existing methods easily become hydrophobic or superhydrophobic in air with time. Here, a facile method combined with electrochemical etching and boiling water immersion is developed to fabricate long-term underwater superoleophobic surfaces. The surface morphologies and chemical compositions are investigated. The results show that the electrochemically etched and boiling-water immersed Al surfaces have excellent long-term superhydrophilicity in air for over 1 year and boehmite plays an important role in maintaining long-term stability of wettability. Based on the fabricated underwater superoleophobic surfaces, a special method and device were developed to realize the underwater lossless manipulation of immiscible organic liquid droplets with a large volume. The capture and release of liquid droplets were realized by controlling the resultant force of the applied driving pressure, gravity and buoyancy. The research has potential application in research-fields such as the transfer of valuable reagents, accurate control of miniature chemical reactions, droplet-based reactors, and eliminates contamination of manipulator components. PMID:27550427

  3. Fabrication of Long-Term Underwater Superoleophobic Al Surfaces and Application on Underwater Lossless Manipulation of Non-Polar Organic Liquids

    NASA Astrophysics Data System (ADS)

    Song, Jinlong; Huang, Liu; Lu, Yao; Liu, Xin; Deng, Xu; Yang, Xiaolong; Huang, Shuai; Sun, Jing; Jin, Zhuji; Parkin, Ivan P.

    2016-08-01

    Underwater superoleophobic surfaces have different applications in fields from oil/water separation to underwater lossless manipulation. This kind of surfaces can be easily transformed from superhydrophilic surfaces in air, which means the stability of superhydrophilicity in air determines the stability of underwater superoleophobicity. However, superhydrophilic surfaces fabricated by some existing methods easily become hydrophobic or superhydrophobic in air with time. Here, a facile method combined with electrochemical etching and boiling water immersion is developed to fabricate long-term underwater superoleophobic surfaces. The surface morphologies and chemical compositions are investigated. The results show that the electrochemically etched and boiling-water immersed Al surfaces have excellent long-term superhydrophilicity in air for over 1 year and boehmite plays an important role in maintaining long-term stability of wettability. Based on the fabricated underwater superoleophobic surfaces, a special method and device were developed to realize the underwater lossless manipulation of immiscible organic liquid droplets with a large volume. The capture and release of liquid droplets were realized by controlling the resultant force of the applied driving pressure, gravity and buoyancy. The research has potential application in research-fields such as the transfer of valuable reagents, accurate control of miniature chemical reactions, droplet-based reactors, and eliminates contamination of manipulator components.

  4. OPTICAL correlation identification technology applied in underwater laser imaging target identification

    NASA Astrophysics Data System (ADS)

    Yao, Guang-tao; Zhang, Xiao-hui; Ge, Wei-long

    2012-01-01

    The underwater laser imaging detection is an effective method of detecting short distance target underwater as an important complement of sonar detection. With the development of underwater laser imaging technology and underwater vehicle technology, the underwater automatic target identification has gotten more and more attention, and is a research difficulty in the area of underwater optical imaging information processing. Today, underwater automatic target identification based on optical imaging is usually realized with the method of digital circuit software programming. The algorithm realization and control of this method is very flexible. However, the optical imaging information is 2D image even 3D image, the amount of imaging processing information is abundant, so the electronic hardware with pure digital algorithm will need long identification time and is hard to meet the demands of real-time identification. If adopt computer parallel processing, the identification speed can be improved, but it will increase complexity, size and power consumption. This paper attempts to apply optical correlation identification technology to realize underwater automatic target identification. The optics correlation identification technology utilizes the Fourier transform characteristic of Fourier lens which can accomplish Fourier transform of image information in the level of nanosecond, and optical space interconnection calculation has the features of parallel, high speed, large capacity and high resolution, combines the flexibility of calculation and control of digital circuit method to realize optoelectronic hybrid identification mode. We reduce theoretical formulation of correlation identification and analyze the principle of optical correlation identification, and write MATLAB simulation program. We adopt single frame image obtained in underwater range gating laser imaging to identify, and through identifying and locating the different positions of target, we can improve

  5. Influences of acute ethanol exposure on locomotor activities of zebrafish larvae under different illumination.

    PubMed

    Guo, Ning; Lin, Jia; Peng, Xiaolan; Chen, Haojun; Zhang, Yinglan; Liu, Xiuyun; Li, Qiang

    2015-11-01

    Larval zebrafish present unique opportunities to study the behavioral responses of a model organism to environmental challenges during early developmental stages. The purpose of the current study was to investigate the locomotor activities of AB strain zebrafish larvae at 5 and 7 days post-fertilization (dpf) in response to light changes under the influence of ethanol, and to explore potential neurological mechanisms that are involved in ethanol intoxication. AB strain zebrafish larvae at both 5 and 7 dpf were treated with ethanol at 0% (control), 0.1%, 0.25%, 0.5%, 1%, and 2% (v/v%). The locomotor activities of the larvae during alternating light-dark challenges, as well as the locomotor responses immediately following the light transitions, were investigated. The levels of various neurotransmitters were also measured in selected ethanol-treated groups. The larvae at 5 and 7 dpf demonstrated similar patterns of locomotor responses to ethanol treatment. Ethanol treatment at 1% increased the swimming distances of the zebrafish larvae in the dark periods, but had no effect on the swimming distances in the light periods. In contrast, ethanol treatment at 2% increased the swimming distances in the light periods, but did not potentiate the swimming activity in the dark periods, compared to controls. Differences in the levels of neurotransmitters that are involved in norepinephrine, dopamine, and serotonin pathways were also observed in groups with different ethanol treatments. These results indicated the behavioral studies concerning the ethanol effects on locomotor activities of zebrafish larvae could be carried out as early as 5 dpf. The 1% and 2% ethanol-treated zebrafish larvae modeled ethanol effects at different intoxication states, and the differences in neurotransmitter levels suggested the involvement of various neurotransmitter pathways in different ethanol intoxication states.

  6. Software architecture of biomimetic underwater vehicle

    NASA Astrophysics Data System (ADS)

    Praczyk, Tomasz; Szymak, Piotr

    2016-05-01

    Autonomous underwater vehicles are vehicles that are entirely or partly independent of human decisions. In order to obtain operational independence, the vehicles have to be equipped with a specialized software. The main task of the software is to move the vehicle along a trajectory with collision avoidance. Moreover, the software has also to manage different devices installed on the vehicle board, e.g. to start and stop cameras, sonars etc. In addition to the software embedded on the vehicle board, the software responsible for managing the vehicle by the operator is also necessary. Its task is to define mission of the vehicle, to start, to stop the mission, to send emergency commands, to monitor vehicle parameters, and to control the vehicle in remotely operated mode. An important objective of the software is also to support development and tests of other software components. To this end, a simulation environment is necessary, i.e. simulation model of the vehicle and all its key devices, the model of the sea environment, and the software to visualize behavior of the vehicle. The paper presents architecture of the software designed for biomimetic autonomous underwater vehicle (BAUV) that is being constructed within the framework of the scientific project financed by Polish National Center of Research and Development.

  7. Arc spot welding technique for underwater use

    SciTech Connect

    Koga, H.; Ide, Y.; Ogawa, Y.

    1995-12-31

    An arc spot welding equipment with special local cavity shroud was developed for underwater salvaging activity. Arc spot welding for lapped plates is an effective method to recover defects. This method in surface is so simple to use widely in the field of railways and chemical plants manufacturing. But there is some problems on the reliability of joint strength and bead shapes. A special arc spot nozzle to improve welding quality was developed. A small outlet of air jet at the bottom of the nozzle was created to maintain the swirl flow of shielding gas and certain rejection of excessive molten metal. This nozzle covers the welding part completely, then it also works as a local cavity shroud under water. This paper describes the design and function of the nozzle for CO{sub 2} arc spot welding system. A programmable controller manages the welding sequence of shielding gas flow, air jet flow, and arcing time. This welding gun is operated manually, but the operation is only to press the gun on the weld point. After that welding will proceed automatically, and arcing time is about three seconds. Whole time for welding which includes pre and post gas flow time is less than ten seconds for surface use, it is required some more additional pre drying process of welding point for underwater use to guarantee the high quality welding results. Fundamental analysis of welding conditions and the effects of air jet were considered.

  8. Underwater remote-reading dosimeter evaluation

    SciTech Connect

    Clow, H.E.; Emmons, G. )

    1985-01-01

    This paper reports on problems inherent in attempting to measure underwater dose rates and monitor and control diver exposures. At Connecticut Yankee, the authors had a specific procedure in effect to cover diving evolutions; however, the authors were not satisfied with the methods available to us for monitoring a diver's dose during a dive. The authors looked around and discovered that the ideal monitoring method was already at hand. In the past, the authors had successfully used the Xetex 503A Teledose system for high dose rate jobs under are variety of circumstances, but not underwater. The basic Teledose system consists of a base station and five individual electronic dosimeter/transmitters that can be worn by workers. The dosimeters are GM-tube types packaged in high-impact plastic or metal cases, each powered by a single 9-volt battery. The dosimeters do not have their own read-outs - instead, they transmit a coded pulse for each mR detected via a loop antenna to the base station, where the accumulated exposure for each of the five dosimeter units is displayed.

  9. Drosophila Clock Is Required in Brain Pacemaker Neurons to Prevent Premature Locomotor Aging Independently of Its Circadian Function

    PubMed Central

    Issa, Abdul-Raouf; Seugnet, Laurent; Klarsfeld, André

    2017-01-01

    Circadian clocks control many self-sustained rhythms in physiology and behavior with approximately 24-hour periodicity. In many organisms, oxidative stress and aging negatively impact the circadian system and sleep. Conversely, loss of the clock decreases resistance to oxidative stress, and may reduce lifespan and speed up brain aging and neurodegeneration. Here we examined the effects of clock disruptions on locomotor aging and longevity in Drosophila. We found that lifespan was similarly reduced in three arrhythmic mutants (ClkAR, cyc0 and tim0) and in wild-type flies under constant light, which stops the clock. In contrast, ClkAR mutants showed significantly faster age-related locomotor deficits (as monitored by startle-induced climbing) than cyc0 and tim0, or than control flies under constant light. Reactive oxygen species accumulated more with age in ClkAR mutant brains, but this did not appear to contribute to the accelerated locomotor decline of the mutant. Clk, but not Cyc, inactivation by RNA interference in the pigment-dispersing factor (PDF)-expressing central pacemaker neurons led to similar loss of climbing performance as ClkAR. Conversely, restoring Clk function in these cells was sufficient to rescue the ClkAR locomotor phenotype, independently of behavioral rhythmicity. Accelerated locomotor decline of the ClkAR mutant required expression of the PDF receptor and correlated to an apparent loss of dopaminergic neurons in the posterior protocerebral lateral 1 (PPL1) clusters. This neuronal loss was rescued when the ClkAR mutation was placed in an apoptosis-deficient background. Impairing dopamine synthesis in a single pair of PPL1 neurons that innervate the mushroom bodies accelerated locomotor decline in otherwise wild-type flies. Our results therefore reveal a novel circadian-independent requirement for Clk in brain circadian neurons to maintain a subset of dopaminergic cells and avoid premature locomotor aging in Drosophila. PMID:28072817

  10. Suprachiasmatic vasopressin and the circadian regulation of voluntary locomotor behavior.

    PubMed

    Cormier, Holly C; Della-Maggiore, Valeria; Karatsoreos, Ilia N; Koletar, Margaret M; Ralph, Martin R

    2015-01-01

    A role for arginine vasopressin in the circadian regulation of voluntary locomotor behavior (wheel running activity) was investigated in the golden hamster, Mesocricetus auratus. Spontaneous nocturnal running was suppressed in a dose-dependent manner by systemic injections of vasopressin, and also in a concentration-dependent manner by microinjections directly into the hypothalamic suprachiasmatic nucleus. Pre-injections of a vasopressin V1 receptor antagonist into the nucleus reduced the suppression of behavior by vasopressin. Ethogram analyses revealed that peripheral drug injections predominantly increased grooming, flank marking, and sleep-related behaviors. Central injections did not induce sleep, but increased grooming and periods of 'quiet vigilance' (awake but not moving). Nocturnal behavioral profiles following either peripheral or central injections were similar to those shown by untreated animals in the hour prior to the onset of nocturnal wheel running. Site control vasopressin injections into the medial preoptic area or periaqueductal gray increased flank marking and grooming, but had no significant effect on locomotion, suggesting behavioral specificity of a vasopressin target near the suprachiasmatic nucleus. Both peripheral and central administration increased FOS-like immunoreactivity in the retinorecipient core of the suprachiasmatic nucleus. The distribution of FOS-positive cells overlapped the calbindin subregion, but was more extensive, and most calbindin-positive cells did not co-express FOS. We propose a model of temporal behavioral regulation wherein voluntary behavior, such as nocturnal locomotor activity, is inhibited by the activity of neurons in the suprachiasmatic ventrolateral core that project to the posterior hypothalamus and are driven by rhythmic vasopressin input from the dorsomedial shell.

  11. Immature Spinal Locomotor Output in Children with Cerebral Palsy

    PubMed Central

    Cappellini, Germana; Ivanenko, Yury P.; Martino, Giovanni; MacLellan, Michael J.; Sacco, Annalisa; Morelli, Daniela; Lacquaniti, Francesco

    2016-01-01

    Detailed descriptions of gait impairments have been reported in cerebral palsy (CP), but it is still unclear how maturation of the spinal motoneuron output is affected. Spatiotemporal alpha-motoneuron activation during walking can be assessed by mapping the electromyographic activity profiles from several, simultaneously recorded muscles onto the anatomical rostrocaudal location of the motoneuron pools in the spinal cord, and by means of factor analysis of the muscle activity profiles. Here, we analyzed gait kinematics and EMG activity of 11 pairs of bilateral muscles with lumbosacral innervation in 35 children with CP (19 diplegic, 16 hemiplegic, 2–12 years) and 33 typically developing (TD) children (1–12 years). TD children showed a progressive reduction of EMG burst durations and a gradual reorganization of the spatiotemporal motoneuron output with increasing age. By contrast, children with CP showed very limited age-related changes of EMG durations and motoneuron output, as well as of limb intersegmental coordination and foot trajectory control (on both sides for diplegic children and the affected side for hemiplegic children). Factorization of the EMG signals revealed a comparable structure of the motor output in children with CP and TD children, but significantly wider temporal activation patterns in children with CP, resembling the patterns of much younger TD infants. A similar picture emerged when considering the spatiotemporal maps of alpha-motoneuron activation. Overall, the results are consistent with the idea that early injuries to developing motor regions of the brain substantially affect the maturation of the spinal locomotor output and consequently the future locomotor behavior. PMID:27826251

  12. Operation of electrothermal and electrostatic MUMPs microactuators underwater

    NASA Astrophysics Data System (ADS)

    Sameoto, Dan; Hubbard, Ted; Kujath, Marek

    2004-10-01

    Surface-micromachined actuators made in multi-user MEMS processes (MUMPs) have been operated underwater without modifying the manufacturing process. Such actuators have generally been either electro-thermally or electro-statically actuated and both actuator styles are tested here for suitability underwater. This is believed to be the first time that thermal and electrostatic actuators have been compared for deflection underwater relative to air performance. A high-frequency ac square wave is used to replicate a dc-driven actuator output without the associated problem of electrolysis in water. This method of ac activation, with frequencies far above the mechanical resonance frequencies of the MEMS actuators, has been termed root mean square (RMS) operation. Both thermal and electrostatic actuators have been tested and proved to work using RMS control. Underwater performance has been evaluated by using in-air operation of these actuators as a benchmark. When comparing deflection per volt applied, thermal actuators operate between 5 and 9% of in-air deflection and electrostatic actuators show an improvement in force per volt applied of upwards of 6000%. These results agree with predictions based on the physical properties of the surrounding medium.

  13. Archerfish use their shooting technique to produce adaptive underwater jets.

    PubMed

    Dewenter, Jana; Gerullis, Peggy; Hecker, Alexander; Schuster, Stefan

    2017-03-15

    Archerfish are renowned for dislodging aerial prey using well-aimed shots of water. Recently it has been shown that these fish can shape their aerial jets by adjusting the dynamics of their mouth opening and closing. This allows the fish to adjust their jet to target distance so that they can forcefully hit prey over considerable distances. Here, we suggest that archerfish use the same technique to also actively control jets under water. Fired from close range, the underwater jets are powerful enough to lift up buried food particles, which the fish then can pick up. We trained fish so that we could monitor their mouth opening and closing maneuvers during underwater shooting and compare them with those employed in aerial shooting. Our analysis suggests that the fish use the same dynamic mechanism to produce aerial and underwater jets and that they employ the same basic technique to adjust their jets in both conditions. When food is buried in substrate that consists of large particles, the fish use a brief pulse, but they use a longer one when the substrate is more fine-grained. These findings extend the notion that archerfish can flexibly shape their jets to be appropriate in different contexts and suggest that archerfish shooting might have been shaped both by constraints in aerial and underwater shooting.

  14. Quantifying turbulence microstructure for improvement of underwater imaging

    NASA Astrophysics Data System (ADS)

    Woods, Sarah; Hou, Weilin; Goode, Wesley; Jarosz, Ewa; Weidemann, Alan

    2011-06-01

    Enhancing visibility through scattering media is important in many fields for gaining information from the scattering medium. In the ocean, in particular, enhancement of imaging and visibility is important for divers, navigation, robotics, and target and mine detection and classification. Light scattering from particulates and turbulence in the ocean strongly affects underwater visibility. The magnitude of this degrading effect depends upon the underwater environment, and can rapidly degrade the quality of underwater imaging under certain conditions. To facilitate study of the impact of turbulence upon underwater imaging and to check against our previously developed model, quantified observation of the image degradation concurrent with characterization of the turbulent flow is necessary, spanning a variety of turbulent strengths. Therefore, we present field measurements of turbulence microstructure from the July 2010 Skaneateles Optical Turbulence Exercise (SOTEX), during which images of a target were collected over a 5 m path length at various depths in the water column, concurrent with profiles of the turbulent strength, optical properties, temperature, and conductivity. Turbulence was characterized by the turbulent kinetic energy dissipation (TKED) and thermal dissipation (TD) rates, which were obtained using both a Rockland Scientific Vertical Microstructure Profiler (VMP) and a Nortek Vector velocimeter in combination with a PME CT sensor. While the two instrumental setups demonstrate reasonable agreement, some irregularities highlight the spatial and temporal variability of the turbulence field. Supplementary measurements with the Vector/CT in a controlled laboratory convective tank will shed additional light on the quantitative relationship between image degradation and turbulence strength.

  15. Research on biomimetic underwater vehicles for underwater ISR

    NASA Astrophysics Data System (ADS)

    Szymak, Piotr; Praczyk, Tomasz; Naus, Krzysztof; Szturomski, Bogdan; Malec, Marcin; Morawski, Marcin

    2016-05-01

    Autonomous Biomimetic Underwater Vehicles BUVs driven by an undulating propulsion are a new branch in an area of an underwater robotics. They imitate both the construction and kinematics of a motion of underwater living organisms, e.g. fishes. Such vehicles have several features crucial from the point of view of military applications, e.g. larger secrecy and potential range of operation. The paper presents results of the research on BUVs carried out within two (Polish and EDA) projects both led by Polish Naval Academy. At the beginning, the initial efforts in building Polish BUV called CyberFish are included. Then, selected results of the tests of subsystems, e.g. navigational and 3D model of BUV built within national project are described. Next, the initial research achieved in the international project are showed. At the end, the schedule of the research planned to carry out within both projects is inserted. The paper is mainly focused on the hardware development of the BUVs.

  16. Compressive line sensing underwater imaging system

    NASA Astrophysics Data System (ADS)

    Ouyang, B.; Dalgleish, F. R.; Vuorenkoski, A. K.; Caimi, F. M.; Britton, W.

    2013-05-01

    Compressive sensing (CS) theory has drawn great interest and led to new imaging techniques in many different fields. In recent years, the FAU/HBOI OVOL has conducted extensive research to study the CS based active electro-optical imaging system in the scattering medium such as the underwater environment. The unique features of such system in comparison with the traditional underwater electro-optical imaging system are discussed. Building upon the knowledge from the previous work on a frame based CS underwater laser imager concept, more advantageous for hover-capable platforms such as the Hovering Autonomous Underwater Vehicle (HAUV), a compressive line sensing underwater imaging (CLSUI) system that is more compatible with the conventional underwater platforms where images are formed in whiskbroom fashion, is proposed in this paper. Simulation results are discussed.

  17. Differential Effects of Inhaled Toluene on Locomotor Activity in Adolescent and Adult Rats

    PubMed Central

    Batis, Jeffery C.; Hannigan, John H.; Bowen, Scott E.

    2010-01-01

    Inhalant abuse is a world-wide public health concern among adolescents. Most preclinical studies have assessed inhalant effects in adult animals leaving unclear how behavioral effects differ in younger animals. We exposed adolescent (postnatal day [PN] 28) and adult (PN90) male rats to toluene using 1 of 3 exposure patterns. These patterns modeled those reported in toluene abuse in teens and varied concentration, number and length of exposures, as well as the inter-exposure interval. Animals were exposed repeatedly over 12 days to toluene concentrations of 0, 8,000 or 16,000 parts per million (ppm). Locomotor activity was quantified during toluene exposures and for 30 min following completion of the final daily toluene exposure. For each exposure pattern, there were significant toluene concentration-related increases and decreases in locomotor activity compared to the 0-ppm “air” controls at both ages. These changes depended upon when activity was measured – during or following exposure. Compared to adults, adolescents displayed greater locomotor activity on the first day and generally greater increases in activity over days than adults during toluene exposure. Adults displayed greater locomotor activity than adolescents in the “recovery” period following exposure on the first and subsequent days. Age group differences were clearest following the pattern of paced, brief (5-min) repeated binge exposures. The results suggest that locomotor behavior in rats during and following inhalation of high concentrations of toluene depends on age and the pattern of exposure. The results are consistent with dose-dependent shifts in sensitivity and sensitization or tolerance to repeated toluene in the adolescent animals compared to the adult animals. Alternate interpretations are possible and our interpretation is limited by the range of very high concentrations of toluene used. The results imply that both pharmacological and psychosocial factors contribute to the teen

  18. The influence of locomotor rehabilitation on module quality and post-stroke hemiparetic walking performance.

    PubMed

    Routson, Rebecca L; Clark, David J; Bowden, Mark G; Kautz, Steven A; Neptune, Richard R

    2013-07-01

    Recent studies have suggested the biomechanical subtasks of walking can be produced by a reduced set of co-excited muscles or modules. Individuals post-stroke often exhibit poor inter-muscular coordination characterized by poor timing and merging of modules that are normally independent in healthy individuals. However, whether locomotor therapy can influence module composition and timing and whether these improvements lead to improved walking performance is unclear. The goal of this study was to examine the influence of a locomotor rehabilitation therapy on module composition and timing and post-stroke hemiparetic walking performance. Twenty-seven post-stroke hemiparetic subjects participated in a 12-week locomotor intervention incorporating treadmill training with body weight support and manual trainers accompanied by training overground walking. Electromyography (EMG), kinematic and ground reaction force data were collected from subjects both pre- and post-therapy and from 19 age-matched healthy controls walking on an instrumented treadmill at their self-selected speed. Non-negative matrix factorization was used to identify the module composition and timing from the EMG data. Module timing and composition, and various measures of walking performance were compared pre- and post-therapy. In subjects with four modules pre- and post-therapy, locomotor training resulted in improved timing of the ankle plantarflexor module and a more extended paretic leg angle that allowed the subjects to walk faster and with more symmetrical propulsion. In addition, subjects with three modules pre-therapy increased their number of modules and improved walking performance post-therapy. Thus, locomotor training has the potential to influence module composition and timing, which can lead to improvements walking performance.

  19. The D₂ dopamine receptor and locomotor hyperactivity following bilateral vestibular deafferentation in the rat.

    PubMed

    Stiles, Lucy; Zheng, Yiwen; Darlington, Cynthia L; Smith, Paul F

    2012-02-01

    Rats and mice with bilateral vestibular loss exhibit dramatic locomotor hyperactivity and circling behaviours, which to date cannot be explained. Dysfunction of the striatal dopaminergic system is responsible for a number of known movement disorders and the D(2) dopamine receptor is known to be implicated. Therefore, it is possible that changes in striatal function are responsible for locomotor hyperactivity and circling following bilateral vestibular lesions. The aim of this study was to investigate the effects of the D(2) receptor antagonist, eticlopride (0.02, 0.04 and 0.06mg/kg; s.c.), on locomotor behaviour in rats at 5 months following bilateral vestibular deafferentation (BVD), using an open field maze. The levels of the D(2) receptor protein in the striatum were measured at 1 and 6 months post-BVD using western blotting. BVD rats exhibited locomotor hyperactivity and circling, which eticlopride did not eliminate. However, BVD rats did exhibit a decreased response to the inhibitory effect of eticlopride compared to sham controls at the 0.02 mg/kg dose. There were no changes in the amount of the D(2) receptor in the striatum at 1 or 6 months post-BVD; however, D(2) receptor levels were significantly higher on the right side than the left in both sham and BVD animals. These results suggest that locomotor hyperactivity and circling behaviours following BVD are not due simply to changes in D(2) receptor protein expression in the striatum and that other neurophysiological changes in the brain account for these behaviours following BVD.

  20. Status of Research in Underwater Physiology

    DTIC Science & Technology

    1956-03-01

    Washington, D. C. D C by the 2 Physiology Group. n Panel on Underwater Swimmers JAN 29 1379 Committee on Undersea Warfare tj KU!’ D National Academy v...V. Houston C. F. Wlebusch G. W. Wood, Executive Secretary Physiology Group of the Panel on Underwater Swimmers Christian J. Lambertsen, Chairman...Edward H. Lanphier Loyal G. Goff Kenneth E. Penrod Panel on Underwater Swimmers C. J. Lambertsen, Chairman B. A. Hawkins, LT USNR C. F. Aquadro, LTJG (MC

  1. Overview of a Hybrid Underwater Camera System

    DTIC Science & Technology

    2014-07-01

    298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18 Overview of a Hybrid Underwater Camera System Philip Church*, WeiHn Hou’*, Georges Fournier ...2678-2686, 2012 [3] Fournier G. R.,Bonnier D., Forand J. L., Pace P., "Range-gated underwater laser imaging system", Optical Engineering 32(9...pp. 2185-2190, Sept. 1993. [4] A. D. Weidemann, G. R. Fournier , J. L. Forand and P. Mathieu, 2005. In harbor underwater threat

  2. Inbreeding affects locomotor activity in Drosophila melanogaster at different ages.

    PubMed

    Manenti, Tommaso; Pertoldi, Cino; Moghadam, Neda Nasiri; Nasiri, Neda; Schou, Mads Fristrup; Kjærsgaard, Anders; Cavicchi, Sandro; Loeschcke, Volker

    2015-01-01

    The ability to move is essential for many behavioural traits closely related to fitness. Here we studied the effect of inbreeding on locomotor activity (LA) of Drosophila melanogaster at different ages under both dark and light regimes. We expected to find a decreased LA in inbred lines compared to control lines. We also predicted an increased differentiation between lines due to inbreeding. LA was higher in the dark compared to the light regime for both inbred and outbred control lines. As expected, inbreeding increased phenotypic variance in LA, with some inbred lines showing higher and some lower LA than control lines. Moreover, age per se did not affect LA neither in control nor in inbred lines, while we found a strong line by age interaction between inbred lines. Interestingly, inbreeding changed the daily activity pattern of the flies: these patterns were consistent across all control lines but were lost in some inbred lines. The departure in the daily pattern of LA in inbred lines may contribute to the inbreeding depression observed in inbred natural populations.

  3. Taiwan's underwater cultural heritage documentation management

    NASA Astrophysics Data System (ADS)

    Tung, Y.-Y.

    2015-09-01

    Taiwan is an important trading and maritime channels for many countries since ancient time. Numerous relics lie underwater due to weather, wars, and other factors. In the year of 2006, Bureau of Cultural Heritage (BOCH) entrusted the Underwater Archaeological Team of Academia Sinica to execute the underwater archaeological investigation projects. Currently, we verified 78 underwater targets, with 78 site of those had been recognized as shipwrecks sites. Up to date, there is a collection of 638 underwater objects from different underwater archaeological sites. Those artefacts are distributed to different institutions and museums. As very diverse management methods/systems are applied for every individual institution, underwater cultural heritage data such as survey, excavation report, research, etc. are poorly organized and disseminated for use. For better communication regarding to Taiwan's underwater cultural heritage in every level, a universal format of documentation should be established. By comparing the existing checklist used in Taiwan with guidelines that are followed in other countries, a more intact and appropriate underwater cultural heritage condition documentation system can be established and adapted in Taiwan.

  4. Bathymetric Mapping: Making Underwater Profile Charts.

    ERIC Educational Resources Information Center

    Pettus, Alvin M.

    1998-01-01

    Focuses on mapping activities designed to provide simulated experiences that help students understand the techniques used to measure and represent underwater terrain without making direct visual observations. (DDR)

  5. Underwater laser imaging system (UWLIS)

    SciTech Connect

    DeLong, M.L.; Kulp, T.J.

    1995-03-10

    Practical limitations of underwater imaging systems are reached when the noise in the back scattered radiation generated in the water between the imaging system and the target obscures the spatial contrast and the resolution necessary for target discovery and identification. The advent of high power lasers operating in the oceanic transmission window of the visible spectrum (blue-green portion) has led to improved experimental illumination systems for underwater imaging The properties of laser bearm in range-gated and synchronously scanned devices take advantage of the unique temporal and spatial coherence effect of common volume back scatter to reduce or eliminate noise, increase signal to noise levels. Synchronously scanned systems rely on the highly collimated nature of the laser beam for spatial rejection of common volume back scatter. A synchronous, raster-scanning underwater laser imaging system (UWLIS) has been developed at Lawrence liver-more National Laboratory. The present UWLIS system differs from earlier synchronous scanners in its ability to scan in two dimensions at conventional video frame rate (30 Hz). The imaging performance of the present UWLIS was measured at distances of up to 6.3 AL (at a physical distance of 15.2 meters) during an in-water tank test and 4.5 to 5.0 AL (at a physical distance of 30 meters) during open water oceanic testing. The test results indicate that the UWLIS system is already capable of extending the underwater imaging range beyond that of conventional floodlight illuminated SIT cameras. The real or near real time frame rates of the UWLIS make possible operations in a mode in which the platform speed is randomly varied. This is typical of the operational environment in which the platform is often maneuvered above and around rugged seafloor terrain`s and obstacles.

  6. Solidification of underwater wet welds

    SciTech Connect

    Pope, A.M.; Medeiros, R.C. de; Liu, S.

    1995-12-31

    It is well known that the shape of a weld pool can influence the microstructure and segregation pattern of the final solidified weld metal. Mechanical properties and susceptibility to defects are consequently affected by the solidification mode of the weld. In this work the solidification behavior of weld beads deposited in air and underwater wet welding using rutile electrodes were compared. The welds were deposited by gravity feed, on low carbon, manganese steel plates using similar welding conditions. Macroscopic observation of the weld craters showed that welds deposited in air presented an elliptical weld pool. The underwater wet welds, on the other hand, solidified with a tear drop shape. Although the welds differed in shape, their lengths were approximately the same. Microscopic examinations carried out on transverse, normal and longitudinal sections revealed a coarser columnar grain structure in the underwater welds. These results suggest that the tear-drop shaped pool induced solidification in a preferred orientation with segregation more likely in welds deposited under wet conditions. This change in weld pool geometry can be explained by the surface heat loss conditions that occur in a wet weld: slower when covered by the steam bubble and faster in the region in contact with water behind the pool.

  7. Development of tools and techniques for monitoring underwater artifacts

    NASA Astrophysics Data System (ADS)

    Lazar, Iulian; Ghilezan, Alin; Hnatiuc, Mihaela

    2016-12-01

    The different assessments provide information on the best methods to approach an artifact. The presence and extent of potential threats to archaeology must also be determined. In this paper we present an underwater robot, built in the laboratory, able to identify the artifact and to get it to the surface. It is an underwater remotely operated vehicle (ROV) which can be controlled remotely from the shore, a boat or a control station and communication is possible through an Ethernet cable with a maximum length of 100 m. The robot is equipped with an IP camera which sends real time images that can be accessed anywhere from within the network. The camera also has a microSD card to store the video. The methods developed for data communication between the robot and the user is present. A communication protocol between the client and server is developed to control the ROV.

  8. Visual inspection of sea bottom structures by an autonomous underwater vehicle.

    PubMed

    Foresti, G L

    2001-01-01

    This paper describes a vision-based system for inspections of underwater structures, e.g., pipelines, cables, etc., by an autonomous underwater vehicle (AUV). Usually underwater inspections are performed by remote operated vehicles (ROVs) driven by human operators placed in a support vessel. However, this task is often challenging, especially in conditions of poor visibility or in presence of strong currents. The system proposed allows the AUV to accomplish the task in autonomy. Moreover, the use of a three-dimensional (3-D) model of the environment and of an extended Kalman filter (EKF) allows the guidance and the control of the vehicle in real time. Experiments done on real underwater images have demonstrated the validity of the proposed method and its efficiency in the case of critical and complex situations.

  9. Underwater audiogram of the California sea lion by the conditioned vocalization technique1

    PubMed Central

    Schusterman, Ronald J.; Balliet, Richard F.; Nixon, James

    1972-01-01

    Conditioning techniques were developed demonstrating that pure tone frequencies under water can exert nearly perfect control over the underwater click vocalizations of the California sea lion (Zalophus californianus). Conditioned vocalizations proved to be a reliable way of obtaining underwater sound detection thresholds in Zalophus at 13 different frequencies, covering a frequency range of 250 to 64,000 Hz. The audiogram generated by these threshold measurements suggests that under water, the range of maximal sensitivity for Zalophus lies between one and 28 kHz with best sensitivity at 16 kHz. Between 28 and 36 kHz there is a loss in sensitivity of 60 dB/octave. However, with relatively intense acoustic signals (> 38 dB re 1 μb underwater), Zalophus will respond to frequencies at least as high as 192 kHz. These results are compared with the underwater hearing of other marine mammals. ImagesFig. 1. PMID:5033891

  10. Developing and testing a pushbroom camera motion control system: using a lidar-based streak tube camera for studying the influence of water waves on underwater light structure detection

    NASA Astrophysics Data System (ADS)

    Bostater, Charles R., Jr.; Ghir, Teddy; Naro-Norman, Scott; Huddleston, Lisa H.; Bassetti, Luce; Mitra, Kunal; Das, Champak; Trivedi, Ashish

    2004-02-01

    A pushbroom sensor motion control system was developed for use in conjunction with a pulsed laser fan beam, streak tube camera, and a high speed low light level camera . The LIDAR and camera control system was tested to study the influence of water waves upon active-passive remote sensing systems and associated models that require pushbroom sensor motion. A pulsed laser fan beam signal at 532 nm was recorded using a streak tube camera and a (high speed, low light level, high quantum efficiency) digital CCD camera. Tests were conducted in 3 different water tanks, including 2 tanks with water waves (the longest wave tank or channel is 60 m long). Capillary waves, ~1 cm wavelength) were generated using an acoustic wave source generator. Streak tube camera and CCD images were collected in conjunction with a 532 nm pico-second short pulse laser. Images collected demonstrate the pulse stretching around submerged water targets as well as the ability to discriminate water depth of submerged targets in shallow water types. In turbid water, the pulsed layer backscatter structure showed a nearly random return as a function of depth if the signal was attenuated before reaching the bottom of the water column. The data collected indicated the motion control testing system can accommodate a variety of cameras and instruments in the lab and in the outdoor water wave channel. Data from these camera systems are being used to help validate analytical and Monte Carlo models of the water surface structure, and the underwater light field structure (pulse stretching) as well as to validate other LIDAR applications used in bathymetric and hydrographic surveys of coastal waters and marine inlets for physical and biological (submerged vegetation) surveys.

  11. Morphine-induced sensitization of locomotor activity in mice: effect of social isolation on plasma corticosterone levels.

    PubMed

    Francès, H; Graulet, A; Debray, M; Coudereau, J P; Guéris, J; Bourre, J M

    2000-03-31

    This study examined the influence of social isolation on behavioural sensitization to the locomotor effect of morphine and the link between this behaviour and plasma corticosterone concentrations. Four weeks isolation induced an increase in the locomotor effect of morphine. In social and isolated mice, repeated administrations (6) of morphine (one injection every 3 or 4 days) followed by 3 h in an actimeter induced behavioural sensitization to the locomotor effect of morphine. No interaction was observed between social isolation and behavioural sensitization to morphine. Resocializing previously isolated mice for 3 weeks reduced the morphine-induced locomotor effect without altering the behavioural sensitization. Corticosterone plasma levels were more increased (416%) in mice isolated 5 weeks than in mice isolated for 2 weeks (243%) and they return to the control levels following 3 weeks of resocialization. Since there was no interaction between the increase in morphine locomotor effect induced by social isolation and the morphine-induced behavioural sensitization, it is suggested that each of these two events acts independently. Whether or not a common mechanism (plasma corticosterone levels?) partly underlies both effects, the result resembles a simple additive effect.

  12. Effects of training and testosterone on muscle fiber types and locomotor performance in male six-lined racerunners (Aspidoscelis sexlineata).

    PubMed

    O'Connor, Jennifer L; McBrayer, Lance D; Higham, Timothy E; Husak, Jerry F; Moore, Ignacio T; Rostal, David C

    2011-01-01

    Testosterone (T) is thought to affect a variety of traits important for fitness, including coloration, the size of sexual ornaments, aggression, and locomotor performance. Here, we investigated the effects of experimentally elevated T and locomotor training on muscle physiology and running performance in a nonterritorial male lizard species (Aspidoscelis sexlineata). Additionally, several morphological attributes were quantified to examine other characters that are likely affected by T and/or a training regimen. Neither training alone nor training with T supplementation resulted in increased locomotor performance. Instead, we found that T and training resulted in a decrease in each of three locomotor performance variables as well as in hematocrit, ventral coloration, and testis size. Strikingly, neither the size nor the fiber composition of the iliofibularis or gastrocnemius muscles was different among the two treatments or a group of untrained control animals. Hence, the relationships among T, training, and associated characters are not clear. Our results offer important insights for those hoping to conduct laboratory manipulations on nonmodel organisms and highlight the challenges of studying both training effects and the effects of steroid hormones on locomotor performance.

  13. Role of DSCAM in the development of the spinal locomotor and sensorimotor circuits.

    PubMed

    Thiry, Louise; Lemieux, Maxime; D Laflamme, Olivier; Bretzner, Frédéric

    2016-03-01

    Locomotion is controlled by spinal circuits that generate rhythm and coordinate left-right and flexor-extensor motoneuronal activities. The outputs of motoneurons and spinal interneuronal circuits are shaped by sensory feedback, relaying peripheral signals that are critical to the locomotor and postural control. Several studies in invertebrates and vertebrates have argued that the Down syndrome cell adhesion molecule (DSCAM) would play an important role in the normal development of neural circuits through cell spacing and targeting, axonal and dendritic branching, and synapse establishment and maintenance. Although there is evidence that DSCAM is important for the normal development of neural circuits, little is known about its functional contribution to spinal motor circuits. We show here that adult DSCAM(2J) mutant mice, lacking DSCAM, exhibit a higher variability in their locomotor pattern and rhythm during treadmill locomotion. Retrograde tracing studies in neonatal isolated spinal cords show an increased number of spinal commissural interneurons, which likely contributes to reducing the left-right alternation and to increasing the flexor/swing duration during neonatal and adult locomotion. Moreover, our results argue that, by reducing the peripheral excitatory drive onto spinal motoneurons, the DSCAM mutation reduces or abolishes spinal reflexes in both neonatal isolated spinal cords and adult mice, thus likely impairing sensorimotor control. Collectively, our functional, electrophysiological, and anatomical studies suggest that the mammalian DSCAM protein is involved in the normal development of spinal locomotor and sensorimotor circuits.

  14. Seeking Teachers for Underwater Robotics PD Program

    ERIC Educational Resources Information Center

    McGrath, Beth; Sayres, Jason

    2012-01-01

    With funding from the National Science Foundation (NSF), ITEEA members will contribute to the development of a hybrid professional development program designed to facilitate the scale-up of an innovative underwater robotics curriculum. WaterBotics[TM] is an underwater robotics curriculum that targets students in middle and high school classrooms…

  15. The locomotor anatomy of Australopithecus afarensis.

    PubMed

    Stern, J T; Susman, R L

    1983-03-01

    The postcranial skeleton of Australopithecus afarensis from the Hadar Formation, Ethiopia, and the footprints from the Laetoli Beds of northern Tanzania, are analyzed with the goal of determining (1) the extent to which this ancient hominid practiced forms of locomotion other than terrestrial bipedality, and (2) whether or not the terrestrial bipedalism of A. afarensis was notably different from that of modern humans. It is demonstrated that A. afarensis possessed anatomic characteristics that indicate a significant adaptation for movement in the trees. Other structural features point to a mode of terrestrial bipedality that involved less extension at the hip and knee than occurs in modern humans, and only limited transfer of weight onto the medial part of the ball of the foot, but such conclusions remain more tentative than that asserting substantive arboreality. A comparison of the specimens representing smaller individuals, presumably female, to those of larger individuals, presumably male, suggests sexual differences in locomotor behavior linked to marked size dimorphism. The males were probably less arboreal and engaged more frequently in terrestrial bipedalism. In our opinion, A. afarensis from Hadar is very close to what can be called a "missing link." We speculate that earlier representatives of the A. afarensis lineage will present not a combination of arboreal and bipedal traits, but rather the anatomy of a generalized ape.

  16. Evidence That GABA Mediates Dopaminergic and Serotonergic Pathways Associated with Locomotor Activity in Juvenile Chinook Salmon (Oncorhynchus tshawytscha)

    USGS Publications Warehouse

    Clements, S.; Schreck, C.B.

    2004-01-01

    The authors examined the control of locomotor activity in juvenile salmon (Oncorhynchus tshawytscha) by manipulating 3 neurotransmitter systems-gamma-amino-n-butyric acid (GABA), dopamine, and serotonin-as well as the neuropeptide corticotropin releasing hormone (CRH). Intracerebroventricular (ICV) injections of CRH and the GABAAagonist muscimol stimulated locomotor activity. The effect of muscimol was attenuated by administration of a dopamine receptor antagonist, haloperidol. Conversely, the administration of a dopamine uptake inhibitor (4???,4??? -difluoro-3-alpha-[diphenylmethoxy] tropane hydrochloride [DUI]) potentiated the effect of muscimol. They found no evidence that CRH-induced hyperactivity is mediated by dopaminergic systems following concurrent injections of haloperidol or DUI with CRH. Administration of muscimol either had no effect or attenuated the locomotor response to concurrent injections of CRH and fluoxetine, whereas the GABAA antagonist bicuculline methiodide potentiated the effect of CRH and fluoxetine.

  17. [The new technologies of kinesiotherapy for the rehabilitation of the patients suffering from the post-stroke locomotor disorders].

    PubMed

    Gusarova, S A; Styazhkina, E M; Gurkina, M V; Chesnikova, E I; Sycheva, A Yu

    2016-01-01

    This paper was designed to report the results of the application of two therapeutic modalities for the rehabilitation of 44 patients presenting with post-stroke locomotor disorders in the form of spastic hemiparesis. The patients allocated to the main group were treated with the use of the new kinesiotherapeutic methods including cryomassage and the Armeo robotic complex. The patients of the control group had to perform traditional therapeutic physical exercises in combination with classical massage and remedial gymnastics. It is concluded that the application of the combination of the modern kinesiotherapeutic factors exerting the positive corrective influence on different aspects of the locomotor deficiency in the upper extremities and the psychoemotional status of the patients has advantages over traditional physical exercise therapy in terms of clinical efficiency because it enhances the rehabilitative potential for these patients with serious locomotor problems.

  18. Quantifying the Dynamic Ocean Surface Using Underwater Radiometric Measurements

    DTIC Science & Technology

    2013-09-30

    Radiometric Measurements Dick K.P. Yue Center for Ocean Engineering Massachusetts Institute of Technology Room 5-321 77 Massachusetts Ave...comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE 30 SEP 2013 2. REPORT TYPE 3. DATES ...COVERED 00-00-2013 to 00-00-2013 4. TITLE AND SUBTITLE Quantifying the Dynamic Ocean Surface Using Underwater Radiometric Measurements 5a

  19. Quantifying the Dynamic Ocean Surface Using Underwater Radiometric Measurement

    DTIC Science & Technology

    2013-09-30

    Radiometric Measurement Lian Shen Department of Mechanical Engineering & St. Anthony Falls Laboratory University of Minnesota Minneapolis, MN...information if it does not display a currently valid OMB control number. 1. REPORT DATE 30 SEP 2013 2. REPORT TYPE 3. DATES COVERED 00-00-2013 to 00-00...2013 4. TITLE AND SUBTITLE Quantifying the Dynamic Ocean Surface Using Underwater Radiometric Measurement 5a. CONTRACT NUMBER 5b. GRANT NUMBER

  20. The anatomy and physiology of the locomotor system.

    PubMed

    Farley, Alistair; McLafferty, Ella; Hendry, Charles

    Mobilisation is one of the activities of living. The term locomotor system refers to those body tissues and organs responsible for movement. Nurses and healthcare workers should be familiar with the body structures that enable mobilisation to assist those in their care with this activity. This article outlines the structure and function of the locomotor system, including the skeleton, joints, muscles and muscle attachments. Two common bone disorders, osteoporosis and osteoarthritis, are also considered.

  1. Underwater Ship Husbandry Discharges

    DTIC Science & Technology

    2011-11-01

    which entered into force in September of 2008, prohibits the use of harmful organotins such as tributyltin ( TBT ) in AFCs used on international...States. The use of TBT AFCs is explicitly prohibited under the VGP, and vessels must remove such coatings or paint over them to prevent toxic...for TBT is consistent with the 1998 Organotin Anti-Foulant Paint Control Act, 33 U.S.C. 2403(a) which generally prohibits application of AFCs

  2. Diurnal locomotor activity and oxidative metabolism of the suprachiasmatic nucleus in two models of hepatic insufficiency.

    PubMed

    Lopez, Laudino; Cimadevilla, Jose M; Aller, Maria A; Arias, Jaime; Nava, M Paz; Arias, Jorge L

    2003-08-15

    Subjects with hepatic cirrhosis develop alterations of several rhythmic behavioural and biochemical patterns. Since most cirrhotic patients combine portal hypertension and hepatic impairment, our work aims to assess the extent to which rhythmical changes can be due to hepatic insufficiency or portal hypertension. This was done using two experimental models in rats, portacaval shunt model (PC) and portal hypertension by a triple stenosing ligature of the portal vein (PH). We assess diurnal locomotor activity and determine the oxidative metabolism of the suprachiasmatic nucleus (SCN) by histochemical determination of cytochrome oxidase (COX). The results show that animals with PC have altered diurnal locomotor rhythm compared to control and PH rats (p<0.001). They also present lower COX activity in the SCN (p<0.05). We conclude that rhythmic alterations are due to hepatic insufficiency and not to portal hypertension.

  3. LMTK3 deficiency causes pronounced locomotor hyperactivity and impairs endocytic trafficking.

    PubMed

    Inoue, Takeshi; Hoshina, Naosuke; Nakazawa, Takanobu; Kiyama, Yuji; Kobayashi, Shizuka; Abe, Takaya; Yamamoto, Toshifumi; Manabe, Toshiya; Yamamoto, Tadashi

    2014-04-23

    LMTK3 belongs to the LMTK family of protein kinases that are predominantly expressed in the brain. Physiological functions of LMTK3 and other members of the LMTK family in the CNS remain unknown. In this study, we performed a battery of behavioral analyses using Lmtk3(-/-) mice and showed that these mice exhibit abnormal behaviors, including pronounced locomotor hyperactivity, reduced anxiety behavior, and decreased depression-like behavior. Concurrently, the dopamine metabolite levels and dopamine turnover rate are increased in the striata of Lmtk3(-/-) mice compared with wild-type controls. In addition, using cultured primary neurons from Lmtk3(-/-) mice, we found that LMTK3 is involved in the endocytic trafficking of N-methyl-d-aspartate receptors, a type of ionotropic glutamate receptor. Altered membrane traffic of the receptor in Lmtk3(-/-) neurons may underlie behavioral abnormalities in the mutant animals. Together, our data suggest that LMTK3 plays an important role in regulating locomotor behavior in mice.

  4. Habituation Training Improves Locomotor Performance in a Forced Running Wheel System in Rats

    PubMed Central

    Toval, Angel; Baños, Raúl; De la Cruz, Ernesto; Morales-Delgado, Nicanor; Pallarés, Jesús G.; Ayad, Abdelmalik; Tseng, Kuei Y.; Ferran, Jose L.

    2017-01-01

    Increasing evidence supports that physical activity promotes mental health; and regular exercise may confer positive effects in neurological disorders. There is growing number of reports that requires the analysis of the impact of physical activity in animal models. Exercise in rodents can be performed under voluntary or forced conditions. The former presents the disadvantage that the volume and intensity of exercise varies from subject to subject. On the other hand, a major challenge of the forced training protocol is the low level of performance typically achieved within a given session. Thus, the aim of the present study was to evaluate the effectiveness of gradual increasing of the volume and intensity (training habituation protocol) to improve the locomotor performance in a forced running-wheel system in rats. Sprague-Dawley rats were randomly assigned to either a group that received an exercise training habituation protocol, or a control group. The locomotor performance during forced running was assessed by an incremental exercise test. The experimental results reveal that the total running time and the distance covered by habituated rats was significantly higher than in control ones. We conclude that the exercise habituation protocol improves the locomotor performance in forced running wheels. PMID:28337132

  5. Modelling spinal circuitry involved in locomotor pattern generation: insights from the effects of afferent stimulation

    PubMed Central

    Rybak, Ilya A; Stecina, Katinka; Shevtsova, Natalia A; McCrea, David A

    2006-01-01

    A computational model of the mammalian spinal cord circuitry incorporating a two-level central pattern generator (CPG) with separate half-centre rhythm generator (RG) and pattern formation (PF) networks has been developed from observations obtained during fictive locomotion in decerebrate cats. Sensory afferents have been incorporated in the model to study the effects of afferent stimulation on locomotor phase switching and step cycle period and on the firing patterns of flexor and extensor motoneurones. Here we show that this CPG structure can be integrated with reflex circuits to reproduce the reorganization of group I reflex pathways occurring during locomotion. During the extensor phase of fictive locomotion, activation of extensor muscle group I afferents increases extensor motoneurone activity and prolongs the extensor phase. This extensor phase prolongation may occur with or without a resetting of the locomotor cycle, which (according to the model) depends on the degree to which sensory input affects the RG and PF circuits, respectively. The same stimulation delivered during flexion produces a temporary resetting to extension without changing the timing of following locomotor cycles. The model reproduces this behaviour by suggesting that this sensory input influences the PF network without affecting the RG. The model also suggests that the different effects of flexor muscle nerve afferent stimulation observed experimentally (phase prolongation versus resetting) result from opposing influences of flexor group I and II afferents on the PF and RG circuits controlling the activity of flexor and extensor motoneurones. The results of modelling provide insights into proprioceptive control of locomotion. PMID:17008375

  6. Underwater holography: past and future

    NASA Astrophysics Data System (ADS)

    Watson, John

    2006-05-01

    Holography is a well-known optical technique which can provide valuable information on the location and distribution of small particles in three-dimensional space. For several years now, we have utilised holography for high-precision subsea inspection and measurement. One specific application which spurred much of our work was the need for high-precision inspection and analysis of plankton sizes, distribution and species identification. To this end we have developed a subsea holographic camera (HoloMar) for recording of plankton and other marine organisms in situ in their natural environment. This camera is unique in that it is able to record simultaneous in-line and off-axis holograms to cover a range of size of marine organisms from a few microns to tens of millimetres and at concentrations from a few particles per cubic centimetre to dense aggregates. Holograms of aquatic systems of up to 50000 cm 3 volume (off-axis) and 9500 cm 3 (in-line), have been recorded in situ, using a pulsed laser (Q-switched, frequency-doubled Nd-YAG, 532 nm). The use of a pulsed laser effectively "freezes" the scene at a given instant. Although the recording of the holograms takes place in water, replay of the image is carried out in the laboratory in air, using the projected (real) image mode of reconstruction. By precision translation of a computer-controlled video-camera through the replayed image volume and performing "optical sectioning" on the image, individual organisms can be isolated and their size, shape and relative location precisely determined. Image processing algorithms, will allow optimisation of the holographic image together with automated identification of individual species and enumeration of concentrations. The local interactions between different organisms and particles can be observed, recorded and quantitatively determined. Following initial laboratory and observation tank testing, the holo-camera was deployed in a sea loch in the West of Scotland to a depth of

  7. SOUNET: Self-Organized Underwater Wireless Sensor Network

    PubMed Central

    Kim, Hee-won; Cho, Ho-Shin

    2017-01-01

    In this paper, we propose an underwater wireless sensor network (UWSN) named SOUNET where sensor nodes form and maintain a tree-topological network for data gathering in a self-organized manner. After network topology discovery via packet flooding, the sensor nodes consistently update their parent node to ensure the best connectivity by referring to the time-varying neighbor tables. Such a persistent and self-adaptive method leads to high network connectivity without any centralized control, even when sensor nodes are added or unexpectedly lost. Furthermore, malfunctions that frequently happen in self-organized networks such as node isolation and closed loop are resolved in a simple way. Simulation results show that SOUNET outperforms other conventional schemes in terms of network connectivity, packet delivery ratio (PDR), and energy consumption throughout the network. In addition, we performed an experiment at the Gyeongcheon Lake in Korea using commercial underwater modems to verify that SOUNET works well in a real environment. PMID:28157164

  8. SOUNET: Self-Organized Underwater Wireless Sensor Network.

    PubMed

    Kim, Hee-Won; Cho, Ho-Shin

    2017-02-02

    In this paper, we propose an underwater wireless sensor network (UWSN) named SOUNET where sensor nodes form and maintain a tree-topological network for data gathering in a self-organized manner. After network topology discovery via packet flooding, the sensor nodes consistently update their parent node to ensure the best connectivity by referring to the timevarying neighbor tables. Such a persistent and self-adaptive method leads to high network connectivity without any centralized control, even when sensor nodes are added or unexpectedly lost. Furthermore, malfunctions that frequently happen in self-organized networks such as node isolation and closed loop are resolved in a simple way. Simulation results show that SOUNET outperforms other conventional schemes in terms of network connectivity, packet delivery ratio (PDR), and energy consumption throughout the network. In addition, we performed an experiment at the Gyeongcheon Lake in Korea using commercial underwater modems to verify that SOUNET works well in a real environment.

  9. Fish kill from underwater explosions

    USGS Publications Warehouse

    Stuart, David J.

    1962-01-01

    The U.S. Geological Survey has used 23 different shotpoints during two seasons of field work in our seismic study of crustal structure in western United States. Without exception, it has been found that under-water shotpoints result in a more efficient conversion of explosive energy into seismic energy than do drilled-hole shotpoints. This experience, together with elimination of drilling costs, has led to the use of underwater shotpoints wherever possible. Three of the 23 shotpoints were in the Pacific Ocean, and for these we have no detailed information on the fish kill. Another six shotpoints were located in inland bodies of water. These are: * Soda Lake near Fallon, Nevada * Mono Lake near Lee Vining, California * Lake Mead near Boulder City, Nevada * Shasta Lake near Redding, California * C.J. Strike Reservoir near Bruneau, Idaho * Lucky Peak Reservoir near Boise, Idaho The 22 high-explosive charges, weighing a total of 95,100 pounds, that were fired in lakes containing fish life resulted in the known death of 2,413 game fish with a total weight of 759 pounds. The average mortality was 110 game fish or 34.5 pounds of game fish killed per average shot of 4,325 pounds of high-explosives.

  10. Underwater camera with depth measurement

    NASA Astrophysics Data System (ADS)

    Wang, Wei-Chih; Lin, Keng-Ren; Tsui, Chi L.; Schipf, David; Leang, Jonathan

    2016-04-01

    The objective of this study is to develop an RGB-D (video + depth) camera that provides three-dimensional image data for use in the haptic feedback of a robotic underwater ordnance recovery system. Two camera systems were developed and studied. The first depth camera relies on structured light (as used by the Microsoft Kinect), where the displacement of an object is determined by variations of the geometry of a projected pattern. The other camera system is based on a Time of Flight (ToF) depth camera. The results of the structural light camera system shows that the camera system requires a stronger light source with a similar operating wavelength and bandwidth to achieve a desirable working distance in water. This approach might not be robust enough for our proposed underwater RGB-D camera system, as it will require a complete re-design of the light source component. The ToF camera system instead, allows an arbitrary placement of light source and camera. The intensity output of the broadband LED light source in the ToF camera system can be increased by putting them into an array configuration and the LEDs can be modulated comfortably with any waveform and frequencies required by the ToF camera. In this paper, both camera were evaluated and experiments were conducted to demonstrate the versatility of the ToF camera.

  11. Control of Movement Initiation Underlies the Development of Balance.

    PubMed

    Ehrlich, David E; Schoppik, David

    2017-02-06

    Balance arises from the interplay of external forces acting on the body and internally generated movements. Many animal bodies are inherently unstable, necessitating corrective locomotion to maintain stability. Understanding how developing animals come to balance remains a challenge. Here we study the interplay among environment, sensation, and action as balance develops in larval zebrafish. We first model the physical forces that challenge underwater balance and experimentally confirm that larvae are subject to constant destabilization. Larvae propel in swim bouts that, we find, tend to stabilize the body. We confirm the relationship between locomotion and balance by changing larval body composition, exacerbating instability and eliciting more frequent swimming. Intriguingly, developing zebrafish come to control the initiation of locomotion, swimming preferentially when unstable, thus restoring preferred postures. To test the sufficiency of locomotor-driven stabilization and the developing control of movement timing, we incorporate both into a generative model of swimming. Simulated larvae recapitulate observed postures and movement timing across early development, but only when locomotor-driven stabilization and control of movement initiation are both utilized. We conclude the ability to move when unstable is the key developmental improvement to balance in larval zebrafish. Our work informs how emerging sensorimotor ability comes to impact how and why animals move when they do.

  12. Evidence for a Role of Orexin/Hypocretin System in Vestibular Lesion-Induced Locomotor Abnormalities in Rats

    PubMed Central

    Pan, Leilei; Qi, Ruirui; Wang, Junqin; Zhou, Wei; Liu, Jiluo; Cai, Yiling

    2016-01-01

    Vestibular damage can induce locomotor abnormalities in both animals and humans. Rodents with bilateral vestibular loss showed vestibular deficits syndrome such as circling, opisthotonus as well as locomotor and exploratory hyperactivity. Previous studies have investigated the changes in the dopamine system after vestibular loss, but the results are inconsistent and inconclusive. Numerous evidences indicate that the orexin system is implicated in central motor control. We hypothesized that orexin may be potentially involved in vestibular loss-induced motor disorders. In this study, we examined the effects of arsanilate- or 3,3′-iminodipropionitrile (IDPN)-induced vestibular lesion (AVL or IVL) on the orexin-A (OXA) labeling in rat hypothalamus using immunohistochemistry. The vestibular lesion-induced locomotor abnormalities were recorded and verified using a histamine H4 receptor antagonist JNJ7777120 (20 mg/kg, i.p.). The effects of the orexin receptor type 1 antagonist SB334867 (16 μg, i.c.v.) on these behavior responses were also investigated. At 72 h post-AVL and IVL, animals exhibited vestibular deficit syndrome and locomotor hyperactivity in the home cages. These responses were significantly alleviated by JNJ7777120 which also eliminated AVL-induced increases in exploratory behavior in an open field. The numbers of OXA-labeled neurons in the hypothalamus were significantly increased in the AVL animals at 72 h post-AVL and in the IVL animals at 24, 48, and 72 h post-IVL. SB334867 significantly attenuated the vestibular deficit syndrome and locomotor hyperactivity at 72 h post-AVL and IVL. It also decreased exploratory behavior in the AVL animals. These results suggested that the alteration of OXA expression might contribute to locomotor abnormalities after acute vestibular lesion. The orexin receptors might be the potential therapeutic targets for vestibular disorders. PMID:27507932

  13. Sex differences in Siberian hamster ultradian locomotor rhythms

    PubMed Central

    Prendergast, Brian J.; Stevenson, Tyler J.; Zucker, Irving

    2014-01-01

    Sex differences in ultradian activity rhythms (URs) and circadian rhythms (CRs) were assessed in Siberian hamsters kept in long day (LD) or short day (SD) photoperiods for 40 weeks. For both sexes URs of locomotor activity were more prevalent, greater in amplitude and more robust in SDs. The UR period was longer in females than males in both day lengths. The reproductive system underwent regression and body mass declined during the initial 10 weeks of SD treatment, and in both sexes these traits spontaneously reverted to the LD phenotype at or before 40 weeks in SD, reflecting the development of neuroendocrine refractoriness to SD patterns of melatonin secretion. Hamsters of both sexes, however, continued to display SD-like URs at the 40 weeks time point. CRs were less prevalent and the waveform less robust and lower in amplitude in SDs than LDs; the SD circadian waveform also did not revert to the long-day phenotype after 40 weeks of SD treatment. Short day lengths enhanced ultradian and diminished circadian rhythms in both sexes. Day length controls several UR characteristics via gonadal steroid and melatonin-independent mechanisms. Sex differences in ultradian timing may contribute to sex diphenisms in rhythms of sleep, food intake and exercise. PMID:23333554

  14. Spinocerebellar ataxia type 13 mutant potassium channel alters neuronal excitability and causes locomotor deficits in zebrafish.

    PubMed

    Issa, Fadi A; Mazzochi, Christopher; Mock, Allan F; Papazian, Diane M

    2011-05-04

    Whether changes in neuronal excitability can cause neurodegenerative disease in the absence of other factors such as protein aggregation is unknown. Mutations in the Kv3.3 voltage-gated K(+) channel cause spinocerebellar ataxia type 13 (SCA13), a human autosomal-dominant disease characterized by locomotor impairment and the death of cerebellar neurons. Kv3.3 channels facilitate repetitive, high-frequency firing of action potentials, suggesting that pathogenesis in SCA13 is triggered by changes in electrical activity in neurons. To investigate whether SCA13 mutations alter excitability in vivo, we expressed the human dominant-negative R420H mutant subunit in zebrafish. The disease-causing mutation specifically suppressed the excitability of Kv3.3-expressing, fast-spiking motor neurons during evoked firing and fictive swimming and, in parallel, decreased the precision and amplitude of the startle response. The dominant-negative effect of the mutant subunit on K(+) current amplitude was directly responsible for the reduced excitability and locomotor phenotype. Our data provide strong evidence that changes in excitability initiate pathogenesis in SCA13 and establish zebrafish as an excellent model system for investigating how changes in neuronal activity impair locomotor control and cause cell death.

  15. Optic Flow Dominates Visual Scene Polarity in Causing Adaptive Modification of Locomotor Trajectory

    NASA Technical Reports Server (NTRS)

    Nomura, Y.; Mulavara, A. P.; Richards, J. T.; Brady, R.; Bloomberg, Jacob J.

    2005-01-01

    Locomotion and posture are influenced and controlled by vestibular, visual and somatosensory information. Optic flow and scene polarity are two characteristics of a visual scene that have been identified as being critical in how they affect perceived body orientation and self-motion. The goal of this study was to determine the role of optic flow and visual scene polarity on adaptive modification in locomotor trajectory. Two computer-generated virtual reality scenes were shown to subjects during 20 minutes of treadmill walking. One scene was a highly polarized scene while the other was composed of objects displayed in a non-polarized fashion. Both virtual scenes depicted constant rate self-motion equivalent to walking counterclockwise around the perimeter of a room. Subjects performed Stepping Tests blindfolded before and after scene exposure to assess adaptive changes in locomotor trajectory. Subjects showed a significant difference in heading direction, between pre and post adaptation stepping tests, when exposed to either scene during treadmill walking. However, there was no significant difference in the subjects heading direction between the two visual scene polarity conditions. Therefore, it was inferred from these data that optic flow has a greater role than visual polarity in influencing adaptive locomotor function.

  16. Deciphering the organization and modulation of spinal locomotor central pattern generators.

    PubMed

    Gordon, Ian T; Whelan, Patrick J

    2006-06-01

    Networks within our spinal cord generate the basic pattern underlying walking. Over the past decade, much progress has been made in our understanding of their function in a variety of vertebrate species. A significant hurdle has been the identification of candidate populations of neurons that are involved in pattern generation in the spinal cord. Recently, systems neuroscientists in collaboration with molecular biologists have begun to dissect the circuitry underlying spinal locomotor networks. These advances have combined genetic and electrophysiological techniques using in vitro preparations of the mouse spinal cord. This review will discuss new advances in the field of spinal locomotor networks with emphasis on the mouse. Many of the behaviors fundamental to animal life, such as breathing, chewing and locomotion, are rhythmic activities controlled by neuronal networks. Discerning which neurons are members of these networks, their synaptic connectivity and their individual electrophysiological properties is essential to our understanding of how rhythmic motor behaviors are produced. It is well known that the spinal cord contains the basic circuitry to produce locomotion. However, identifying neurons and connections within spinal networks is challenging because cells that comprise the locomotor network form part of a heterogeneous mix of interneurons within the ventral spinal cord. Recently, the merging of electrophysiological and genetic approaches has provided new tools to identify classes of interneurons within the spinal cord that contribute to network function. These new findings will be discussed in this review.

  17. Removing sensory input disrupts spinal locomotor activity in the early postnatal period

    PubMed Central

    Acevedo, JeanMarie; Díaz-Ríos, Manuel

    2013-01-01

    Motor patterns driving rhythmic movements of our lower limbs during walking are generated by groups of neurons within the spinal cord, called central pattern generators (CPGs). After suffering a spinal cord injury (SCI), many descending fibers from our brain are severed or become nonfunctional which leaves the spinal CPG network without its initiating drive. Recent studies are focusing on the importance of maintaining sensory stimulation to the legs on SCI patients as a way to initiate and control the CPG locomotor network. We began assessing the role of sensory feedback to the locomotor CPG network by using a neonatal mouse spinal cord preparation were the lower limbs are still attached. Removing sensory feedback coming from the hindlimbs by way of a lower lumbar transection or by ventral root denervation revealed a positive correlation in the ability of sensory input deprivation to disrupt ongoing locomotor activity on older versus younger animals. The differences in the motor responses as a function of age could be correlated with the loss of excitatory activity from sensory afferents. Continued studies on this field could eventually provide key information that translates in the design of novel therapeutic strategies to treat patients that have suffered a SCI. PMID:24043359

  18. Insulin-Dependent Activation of MCH Neurons Impairs Locomotor Activity and Insulin Sensitivity in Obesity.

    PubMed

    Hausen, A Christine; Ruud, Johan; Jiang, Hong; Hess, Simon; Varbanov, Hristo; Kloppenburg, Peter; Brüning, Jens C

    2016-12-06

    Melanin-concentrating-hormone (MCH)-expressing neurons (MCH neurons) in the lateral hypothalamus (LH) are critical regulators of energy and glucose homeostasis. Here, we demonstrate that insulin increases the excitability of these neurons in control mice. In vivo, insulin promotes phosphatidylinositol 3-kinase (PI3K) signaling in MCH neurons, and cell-type-specific deletion of the insulin receptor (IR) abrogates this response. While lean mice lacking the IR in MCH neurons (IR(ΔMCH)) exhibit no detectable metabolic phenotype under normal diet feeding, they present with improved locomotor activity and insulin sensitivity under high-fat-diet-fed, obese conditions. Similarly, obesity promotes PI3 kinase signaling in these neurons, and this response is abrogated in IR(ΔMCH) mice. In turn, acute chemogenetic activation of MCH neurons impairs locomotor activity but not insulin sensitivity. Collectively, our experiments reveal an insulin-dependent activation of MCH neurons in obesity, which contributes via distinct mechanisms to the manifestation of impaired locomotor activity and insulin resistance.

  19. The effect of early environmental manipulation on locomotor sensitivity and methamphetamine conditioned place preference reward.

    PubMed

    Hensleigh, E; Pritchard, L M

    2014-07-15

    Early life stress leads to several effects on neurological development, affecting health and well-being later in life. Instances of child abuse and neglect are associated with higher rates of depression, risk taking behavior, and an increased risk of drug abuse later in life. This study used repeated neonatal separation of rat pups as a model of early life stress. Rat pups were either handled and weighed as controls or separated for 180 min per day during postnatal days 2-8. In adulthood, male and female rats were tested for methamphetamine conditioned place preference reward and methamphetamine induced locomotor activity. Tissue samples were collected and mRNA was quantified for the norepinephrine transporter in the prefrontal cortex and the dopamine transporter in the nucleus accumbens. Results indicated rats given methamphetamine formed a conditioned place preference, but there was no effect of early separation or sex. Separated males showed heightened methamphetamine-induced locomotor activity, but there was no effect of early separation for females. Overall females were more active than males in response to both saline and methamphetamine. No differences in mRNA levels were observed across any conditions. These results suggest early neonatal separation affects methamphetamine-induced locomotor activity in a sex-dependent manner but has no effects on methamphetamine conditioned place preference.

  20. QRFP and Its Receptors Regulate Locomotor Activity and Sleep in Zebrafish

    PubMed Central

    Chen, Audrey; Chiu, Cindy N.; Mosser, Eric A.; Kahn, Sohini; Spence, Rory

    2016-01-01

    The hypothalamus plays an important role in regulating sleep, but few hypothalamic sleep-promoting signaling pathways have been identified. Here we demonstrate a role for the neuropeptide QRFP (also known as P518 and 26RFa) and its receptors in regulating sleep in zebrafish, a diurnal vertebrate. We show that QRFP is expressed in ∼10 hypothalamic neurons in zebrafish larvae, which project to the hypothalamus, hindbrain, and spinal cord, including regions that express the two zebrafish QRFP receptor paralogs. We find that the overexpression of QRFP inhibits locomotor activity during the day, whereas mutation of qrfp or its receptors results in increased locomotor activity and decreased sleep during the day. Despite the restriction of these phenotypes to the day, the circadian clock does not regulate qrfp expression, and entrained circadian rhythms are not required for QRFP-induced rest. Instead, we find that QRFP overexpression decreases locomotor activity largely in a light-specific manner. Our results suggest that QRFP signaling plays an important role in promoting sleep and may underlie some aspects of hypothalamic sleep control. SIGNIFICANCE STATEMENT The hypothalamus is thought to play a key role in regulating sleep in vertebrate animals, but few sleep-promoting signaling pathways that function in the hypothalamus have been identified. Here we use the zebrafish, a diurnal vertebrate, to functionally and anatomically characterize the neuropeptide QRFP. We show that QRFP is exclusively expressed in a small number of neurons in the larval zebrafish hypothalamus that project widely in the brain. We also show that QRFP overexpression reduces locomotor activity, whereas animals that lack QRFP signaling are more active and sleep less. These results suggest that QRFP signaling participates in the hypothalamic regulation of sleep. PMID:26865608

  1. Characterization of sacral interneurons that mediate activation of locomotor pattern generators by sacrocaudal afferent input.

    PubMed

    Etlin, Alex; Finkel, Eran; Mor, Yoav; O'Donovan, Michael J; Anglister, Lili; Lev-Tov, Aharon

    2013-01-09

    Identification of the neural pathways involved in retraining the spinal central pattern generators (CPGs) by afferent input in the absence of descending supraspinal control is feasible in isolated rodent spinal cords where the locomotor CPGs are potently activated by sacrocaudal afferent (SCA) input. Here we study the involvement of sacral neurons projecting rostrally through the ventral funiculi (VF) in activation of the CPGs by sensory stimulation. Fluorescent labeling and immunostaining showed that VF neurons are innervated by primary afferents immunoreactive for vesicular glutamate transporters 1 and 2 and by intraspinal neurons. Calcium imaging revealed that 55% of the VF neurons were activated by SCA stimulation. The activity of VF neurons and the sacral and lumbar CPGs was abolished when non-NMDA receptors in the sacral segments were blocked by the antagonist CNQX. When sacral NMDA receptors were blocked by APV, the sacral CPGs were suppressed, VF neurons with nonrhythmic activity were recruited and a moderate-drive locomotor rhythm developed during SCA stimulation. In contrast, when the sacral CPGs were activated by SCA stimulation, rhythmic and nonrhythmic VF neurons were recruited and the locomotor rhythm was most powerful. The activity of 73 and 27% of the rhythmic VF neurons was in-phase with the ipsilateral and contralateral motor output, respectively. Collectively, our studies indicate that sacral VF neurons serve as a major link between SCA and the hindlimb CPGs and that the ability of SCA to induce stepping can be enhanced by the sacral CPGs. The nature of the ascending drive to lumbar CPGs, the identity of subpopulations of VF neurons, and their potential role in activating the locomotor rhythm are discussed.

  2. Reduced locomotor activity and exploratory behavior in CC chemokine receptor 4 deficient mice.

    PubMed

    Ambrée, Oliver; Klassen, Irene; Förster, Irmgard; Arolt, Volker; Scheu, Stefanie; Alferink, Judith

    2016-11-01

    Chemokines and their receptors are key regulators of immune cell trafficking and activation. Recent findings suggest that they may also play pathophysiological roles in psychiatric diseases like depression and anxiety disorders. The CC chemokine receptor 4 (CCR4) and its two ligands, CCL17 and CCL22, are functionally involved in neuroinflammation as well as anti-infectious and autoimmune responses. However, their influence on behavior remains unknown. Here we characterized the functional role of the CCR4-CCL17 chemokine-receptor axis in the modulation of anxiety-related behavior, locomotor activity, and object exploration and recognition. Additionally, we investigated social exploration of CCR4 and CCL17 knockout mice and wild type (WT) controls. CCR4 knockout (CCR4(-/-)) mice exhibited fewer anxiety-related behaviors in the elevated plus-maze, diminished locomotor activity, exploratory behavior, and social exploration, while their recognition memory was not affected. In contrast, CCL17 deficient mice did not show an altered behavior compared to WT mice regarding locomotor activity, anxiety-related behavior, social exploration, and object recognition memory. In the dark-light and object recognition tests, CCL17(-/-) mice even covered longer distances than WT mice. These data demonstrate a mechanistic or developmental role of CCR4 in the regulation of locomotor and exploratory behaviors, whereas the ligand CCL17 appears not to be involved in the behaviors measured here. Thus, either CCL17 and the alternative ligand CCL22 may be redundant, or CCL22 is the main activator of CCR4 in these processes. Taken together, these findings contribute to the growing evidence regarding the involvement of chemokines and their receptors in the regulation of behavior.

  3. Underwater Acoustic Networks: An Acoustic Propagation Model for Simulation of Underwater Acoustic Networks

    DTIC Science & Technology

    2005-12-01

    Applications Underwater sound propagation has been used either for military applications like sonar, mine fields, voice communication , or civilian use such...as hydrographic surveys, oceanographic studies, and marine life research. Wireless communications to this date are a common part in our daily life...and the term wireless is usually associated with over the air communications and not related to underwater communications . Underwater networks may

  4. Mechanisms of Left-Right Coordination in Mammalian Locomotor Pattern Generation Circuits: A Mathematical Modeling View

    PubMed Central

    Talpalar, Adolfo E.; Rybak, Ilya A.

    2015-01-01

    The locomotor gait in limbed animals is defined by the left-right leg coordination and locomotor speed. Coordination between left and right neural activities in the spinal cord controlling left and right legs is provided by commissural interneurons (CINs). Several CIN types have been genetically identified, including the excitatory V3 and excitatory and inhibitory V0 types. Recent studies demonstrated that genetic elimination of all V0 CINs caused switching from a normal left-right alternating activity to a left-right synchronized “hopping” pattern. Furthermore, ablation of only the inhibitory V0 CINs (V0D subtype) resulted in a lack of left-right alternation at low locomotor frequencies and retaining this alternation at high frequencies, whereas selective ablation of the excitatory V0 neurons (V0V subtype) maintained the left–right alternation at low frequencies and switched to a hopping pattern at high frequencies. To analyze these findings, we developed a simplified mathematical model of neural circuits consisting of four pacemaker neurons representing left and right, flexor and extensor rhythm-generating centers interacting via commissural pathways representing V3, V0D, and V0V CINs. The locomotor frequency was controlled by a parameter defining the excitation of neurons and commissural pathways mimicking the effects of N-methyl-D-aspartate on locomotor frequency in isolated rodent spinal cord preparations. The model demonstrated a typical left-right alternating pattern under control conditions, switching to a hopping activity at any frequency after removing both V0 connections, a synchronized pattern at low frequencies with alternation at high frequencies after removing only V0D connections, and an alternating pattern at low frequencies with hopping at high frequencies after removing only V0V connections. We used bifurcation theory and fast-slow decomposition methods to analyze network behavior in the above regimes and transitions between them. The model

  5. Mechanisms of left-right coordination in mammalian locomotor pattern generation circuits: a mathematical modeling view.

    PubMed

    Molkov, Yaroslav I; Bacak, Bartholomew J; Talpalar, Adolfo E; Rybak, Ilya A

    2015-05-01

    The locomotor gait in limbed animals is defined by the left-right leg coordination and locomotor speed. Coordination between left and right neural activities in the spinal cord controlling left and right legs is provided by commissural interneurons (CINs). Several CIN types have been genetically identified, including the excitatory V3 and excitatory and inhibitory V0 types. Recent studies demonstrated that genetic elimination of all V0 CINs caused switching from a normal left-right alternating activity to a left-right synchronized "hopping" pattern. Furthermore, ablation of only the inhibitory V0 CINs (V0D subtype) resulted in a lack of left-right alternation at low locomotor frequencies and retaining this alternation at high frequencies, whereas selective ablation of the excitatory V0 neurons (V0V subtype) maintained the left-right alternation at low frequencies and switched to a hopping pattern at high frequencies. To analyze these findings, we developed a simplified mathematical model of neural circuits consisting of four pacemaker neurons representing left and right, flexor and extensor rhythm-generating centers interacting via commissural pathways representing V3, V0D, and V0V CINs. The locomotor frequency was controlled by a parameter defining the excitation of neurons and commissural pathways mimicking the effects of N-methyl-D-aspartate on locomotor frequency in isolated rodent spinal cord preparations. The model demonstrated a typical left-right alternating pattern under control conditions, switching to a hopping activity at any frequency after removing both V0 connections, a synchronized pattern at low frequencies with alternation at high frequencies after removing only V0D connections, and an alternating pattern at low frequencies with hopping at high frequencies after removing only V0V connections. We used bifurcation theory and fast-slow decomposition methods to analyze network behavior in the above regimes and transitions between them. The model

  6. Two Components of Nocturnal Locomotor Suppression by Light

    PubMed Central

    Morin, Lawrence P.; Lituma, Pablo J.; Studholme, Keith M.

    2010-01-01

    In nocturnal rodents, millisecond light (“flash”) stimuli can induce both a large circadian rhythm phase shift and an associated state change from highly active to quiescence followed by behavioral sleep. Suppression of locomotion (“negative masking”) is an easily measured correlate of the state change. The present mouse studies used both flashes and longer light stimuli (“pulses”) to distinguish initiation from maintenance effects of light on locomotor suppression and to determine whether the locomotor suppression exhibits temporal integration as is thought to be characteristic of phase shift responses to pulse, but not flash, stimuli. In Expt. 1, locomotor suppression increased with irradiance (0.01–100 μW/cm2), in accordance with previous reports. It also increased with stimulus duration (3–3000 sec), but interpretation of this result is complicated by the ability of light to both initiate and maintain locomotor suppression. In Expt. 2, an irradiance response curve was determined using a stimulus series of 10 flashes, 2 msec each, with total flash energy varying from 0.0025 – 110.0 J/m2. This included a test for temporal integration in which the effects of two equal energy series of flashes were compared, but which differed in the number of flashes per series (10 vs 100). The 10 flash series more effectively elicited locomotor suppression than the 100 flash series, a result consistent with prior observations involving flash-induced phase shifts. In Expt. 3, exposure of mice to an 11 hr light stimulus yielded irradiance-dependent locomotor suppression that can be maintained for the entire stimulus duration by a 100 μW/cm2 stimulus. Light has the ability to initiate a time-limited (30–40 min) interval of locomotor suppression (initiation effect) that can be extended by additional light (maintenance effect). Temporal integration resembling that seen in phase shifting responses to light does not exist for either phase shift or locomotor

  7. Comparison of three underwater antennas for use in radiotelemetry

    USGS Publications Warehouse

    Beeman, J.W.; Grant, C.; Haner, P.V.

    2004-01-01

    The radiation patterns of three versions of underwater radiotelemetry antennas were measured to compare the relative reception ranges in the horizontal and vertical planes, which are important considerations when designing detection systems. The received signal strengths of an antenna made by stripping shielding from a section of coaxial cable (stripped coax) and by two versions of a dipole antenna were measured at several orientations relative to a dipole transmit antenna under controlled field conditions. The received signal strengths were greater when the transmit and receive antennas were parallel to each other than when they were perpendicular, indicating that a parallel orientation provides optimal detection range. The horizontal plane radiation pattern of the flexible, stripped coax antenna was similar to that of a rigid dipole antenna, but movement of underwater stripped coax antennas in field applications could affect the orientation of transmit and receive antennas in some applications, resulting in decreased range and variation in received signal strengths. Compared with a standard dipole, a dipole antenna armored by housing within a polyvinyl chloride fitting had a smaller radiation pattern in the horizontal plane but a larger radiation pattern in the vertical plane. Each of these types of underwater antenna can be useful, but detection ranges can be maximized by choosing an appropriate antenna after consideration of the location, relation between transmit and receive antenna orientations, radiation patterns, and overall antenna resiliency.

  8. The design of underwater superoleophobic Ni/NiO microstructures with tunable oil adhesion

    NASA Astrophysics Data System (ADS)

    Zhang, Enshuang; Cheng, Zhongjun; Lv, Tong; Li, Li; Liu, Yuyan

    2015-11-01

    Controlling oil adhesion in water is a fundamental issue in many practical applications for surfaces. Currently, almost all studies on underwater oil adhesion control are concentrated on regulating surface chemistry on polymer surfaces, and structure-dependent underwater oil adhesion is still rare, especially on inorganic materials. Herein, we report a series of underwater superoleophobic Ni/NiO surfaces with controlled oil adhesions by combining electro-deposition and heating techniques. The adhesive forces between an oil droplet and the surfaces can be adjusted from an extremely low (less than 1 μN) to a very high value (about 60 μN), and the tunable effect can be attributed to different wetting states that result from different microstructures on the surfaces. Moreover, the oil-adhesion controllability for different types of oils was also analyzed and the applications of the surface including oil droplet transportation and self-cleaning were discussed. The results reported herein provide a new feasible method for fabrication of underwater superoleophobic surfaces with controlled adhesion, and improve the understanding of the relationship between surface microstructures, adhesion, and the fabrication principle of tunable oil adhesive surfaces.Controlling oil adhesion in water is a fundamental issue in many practical applications for surfaces. Currently, almost all studies on underwater oil adhesion control are concentrated on regulating surface chemistry on polymer surfaces, and structure-dependent underwater oil adhesion is still rare, especially on inorganic materials. Herein, we report a series of underwater superoleophobic Ni/NiO surfaces with controlled oil adhesions by combining electro-deposition and heating techniques. The adhesive forces between an oil droplet and the surfaces can be adjusted from an extremely low (less than 1 μN) to a very high value (about 60 μN), and the tunable effect can be attributed to different wetting states that result from

  9. Active-imaging-based underwater navigation

    NASA Astrophysics Data System (ADS)

    Monnin, David; Schmitt, Gwenaël.; Fischer, Colin; Laurenzis, Martin; Christnacher, Frank

    2015-10-01

    Global navigation satellite systems (GNSS) are widely used for the localization and the navigation of unmanned and remotely operated vehicles (ROV). In contrast to ground or aerial vehicles, GNSS cannot be employed for autonomous underwater vehicles (AUV) without the use of a communication link to the water surface, since satellite signals cannot be received underwater. However, underwater autonomous navigation is still possible using self-localization methods which determines the relative location of an AUV with respect to a reference location using inertial measurement units (IMU), depth sensors and even sometimes radar or sonar imaging. As an alternative or a complementary solution to common underwater reckoning techniques, we present the first results of a feasibility study of an active-imaging-based localization method which uses a range-gated active-imaging system and can yield radiometric and odometric information even in turbid water.

  10. Evolution: Fossil Ears and Underwater Sonar.

    PubMed

    Lambert, Olivier

    2016-08-22

    A key innovation in the history of whales was the evolution of a sonar system together with high-frequency hearing. Fossils of an archaic toothed whale's inner ear bones provide clues for a stepwise emergence of underwater echolocation ability.

  11. Administrator Bolden Calls Underwater NEEMO Crew

    NASA Video Gallery

    From outside their underwater laboratory in Florida, NASA Astronaut and NEEMO 16 Commander Dottie Metcalf-Lindenburger and European Space Agency astronaut Timothy Peake took a call from NASA Admini...

  12. Piezoelectric materials used in underwater acoustic transducers

    SciTech Connect

    Li, Huidong; Deng, Zhiqun; Carlson, Thomas J.

    2012-07-07

    Piezoelectric materials have been used in underwater acoustic transducers for nearly a century. In this paper, we reviewed four different types of piezoelectric materials: piezoelectric ceramics, single crystals, composites, and polymers, which are widely used in underwater acoustic transducers nowadays. Piezoelectric ceramics are the most dominant material type and are used as a single-phase material or one of the end members in composites. Piezoelectric single crystals offer outstanding electromechanical response but are limited by their manufacturing cost. Piezoelectric polymers provide excellent acoustic impedance matching and transducer fabrication flexibility although their piezoelectric properties are not as good as ceramics and single crystals. Composites combined the merits of ceramics and polymers and are receiving increased attention. The typical structure and electromechanical properties of each type of materials are introduced and discussed with respect to underwater acoustic transducer applications. Their advantages and disadvantages are summarized. Some of the critical design considerations when developing underwater acoustic transducers with these materials are also touched upon.

  13. Underwater Grass Comeback Helps Chesapeake Bay

    EPA Pesticide Factsheets

    The fortified Susquehanna Flats, the largest bed of underwater grasses in the Chesapeake Bay, seems able to withstand a major weather punch. Its resilience is contributing to an overall increase in the Bay’s submerged aquatic vegetation.

  14. Sensor Network Architectures for Monitoring Underwater Pipelines

    PubMed Central

    Mohamed, Nader; Jawhar, Imad; Al-Jaroodi, Jameela; Zhang, Liren

    2011-01-01

    This paper develops and compares different sensor network architecture designs that can be used for monitoring underwater pipeline infrastructures. These architectures are underwater wired sensor networks, underwater acoustic wireless sensor networks, RF (Radio Frequency) wireless sensor networks, integrated wired/acoustic wireless sensor networks, and integrated wired/RF wireless sensor networks. The paper also discusses the reliability challenges and enhancement approaches for these network architectures. The reliability evaluation, characteristics, advantages, and disadvantages among these architectures are discussed and compared. Three reliability factors are used for the discussion and comparison: the network connectivity, the continuity of power supply for the network, and the physical network security. In addition, the paper also develops and evaluates a hierarchical sensor network framework for underwater pipeline monitoring. PMID:22346669

  15. Underwater probing with laser radar

    NASA Technical Reports Server (NTRS)

    Carswell, A. I.; Sizgoric, S.

    1975-01-01

    Recent advances in laser and electro optics technology have greatly enhanced the feasibility of active optical probing techniques aimed at the remote sensing of water parameters. This paper describes a LIDAR (laser radar) that has been designed and constructed for underwater probing. The influence of the optical properties of water on the general design parameters of a LIDAR system is considered. Discussion of the specific details in the choice of the constructed LIDAR is given. This system utilizes a cavity dumped argon ion laser transmitter capable of 50 watt peak powers, 10 nanosecond pulses and megahertz pulse repetition rates at 10 different wavelengths in the blue green region of the spectrum. The performance of the system, in proving various types of water, is demonstrated by summarizing the results of initial laboratory and field experiments.

  16. High bandwidth underwater optical communication

    NASA Astrophysics Data System (ADS)

    Hanson, Frank; Radic, Stojan

    2008-01-01

    We report error-free underwater optical transmission measurements at 1 Gbit/s (109 bits/s) over a 2 m path in a laboratory water pipe with up to 36 dB of extinction. The source at 532 nm was derived from a 1064 nm continuous-wave laser diode that was intensity modulated, amplified, and frequency doubled in periodically poled lithium niobate. Measurements were made over a range of extinction by the addition of a Mg(OH)2 and Al(OH)3 suspension to the water path, and we were not able to observe any evidence of temporal pulse broadening. Results of Monte Carlo simulations over ocean water paths of several tens of meters indicate that optical communication data rates >1 Gbit/s can be supported and are compatible with high-capacity data transfer applications that require no physical contact.

  17. Developing Sensorimotor Countermeasures to Mitigate Post-Flight Locomotor Dysfunction

    NASA Technical Reports Server (NTRS)

    Bloomberg, J. J.; Mulavara, A. P.; Cohen, H.; Miller, C. A.; Richards, J. T.; Houser, J.; McDonald, P. V.; Seidler, R. D.; Merkle, L. A.; Stelmach, G. E.

    2001-01-01

    Following spaceflight, crewmembers experience postural and locomotor instability. The magnitude and duration of post-flight sensorimotor disturbances increase with longer duration exposure to microgravity. These post-flight postural and locomotor alterations can pose a risk to crew safety and to mission objectives if nominal or emergency vehicle egress is required immediately following long-duration spaceflight. Gait instabilities could prevent or extend the time required to make an emergency egress from the Orbiter, Crew Return Vehicle or a future Martian lander leading to compromised mission objectives. We propose a countermeasure that aids in maintaining functional locomotor performance. This includes retaining the ability to perform vehicular egress and meet early mission objectives soon after landing on a planetary surface.

  18. Exendin-4 Decreases Amphetamine-induced Locomotor Activity

    PubMed Central

    Erreger, Kevin; Davis, Adeola R.; Poe, Amanda M.; Greig, Nigel H.; Stanwood, Gregg D.; Galli, Aurelio

    2012-01-01

    Glucagon-like peptide-1 (GLP-1) is released in response to nutrient ingestion and is a regulator of energy metabolism and consummatory behaviors through both peripheral and central mechanisms. The GLP-1 receptor (GLP-1R) is widely distributed in the central nervous system, however little is known about how GLP-1Rs regulate ambulatory behavior. The abused psychostimulant amphetamine (AMPH) promotes behavioral locomotor activity primarily by inducing the release of the neurotransmitter dopamine. Here, we identify the GLP-1R agonist exendin-4 (Ex-4) as a modulator of behavioral activation by AMPH. We report that in rats a single acute administration of Ex-4 decreases both basal locomotor activity as well as AMPH-induced locomotor activity. Ex-4 did not induce behavioral responses reflecting anxiety or aversion. Our findings implicate GLP-1R signaling as a novel modulator of psychostimulant-induced behavior and therefore a potential therapeutic target for psychostimulant abuse. PMID:22465309

  19. Quaternary naltrexone reverses radiogenic and morphine-induced locomotor hyperactivity

    SciTech Connect

    Mickley, G.A.; Stevens, K.E.; Galbraith, J.A.; White, G.A.; Gibbs, G.L.

    1984-04-01

    The present study attempted to determine the relative role of the peripheral and central nervous system in the production of morphine-induced or radiation-induced locomotor hyperactivity of the mouse. Toward this end, we used a quaternary derivative of an opiate antagonist (naltrexone methobromide), which presumably does not cross the blood-brain barrier. Quaternary naltrexone was used to challenge the stereotypic locomotor response observed in these mice after either an i.p. injection of morphine or exposure to 1500 rads /sup 60/Co. The quaternary derivative of naltrexone reversed the locomotor hyperactivity normally observed in the C57BL/6J mouse after an injection of morphine. It also significantly attenuated radiation-induced locomotion. The data reported here support the hypothesis of endorphin involvement in radiation-induced and radiogenic behaviors. However, these conclusions are contingent upon further research which more fully evaluates naltrexone methobromide's capacity to cross the blood-brain barrier.

  20. Sources of Underwater Sound and Their Characterization.

    PubMed

    Ainslie, Michael A; de Jong, Christ A F

    2016-01-01

    Because of the history of sonar and sonar engineering, the concept of "source level" is widely used to characterize anthropogenic sound sources, but is it useful for sources other than sonar transmitters? The concept and applicability of source level are reviewed for sonar, air guns, explosions, ships, and pile drivers. International efforts toward the harmonization of the terminology for underwater sound and measurement procedures for underwater sound sources are summarized, with particular attention to the initiatives of the International Organization for Standardization.

  1. The Effects of Underwater Blast on Divers

    DTIC Science & Technology

    2007-11-02

    Any process that causes a non-uniform pressure field generates sound. The acoustic pressure of the sound is related to the rate of change of... caused by the shock wave. Conventionally, this is usually considered to be in the initial peak of the waveform. This quantity is related to the...underwater sound events. The term has been mainly used to describe the pressure pulses caused by the detonation of high explosives underwater, but the term

  2. Affordable underwater wireless optical communication using LEDs

    NASA Astrophysics Data System (ADS)

    Pilipenko, Vladimir; Arnon, Shlomi

    2013-09-01

    In recent years the need for high data rate underwater wireless communication (WC) has increased. Nowadays, the conventional technology for underwater communication is acoustic. However, the maximum data rate that acoustic technology can provide is a few kilobits per second. On the other hand, emerging applications such as underwater imaging, networks of sensors and swarms of underwater vehicles require much faster data rates. As a result, underwater optical WC, which can provide much higher data rates, has been proposed as an alternative means of communication. In addition to high data rates, affordable communication systems become an important feature in the development requirements. The outcome of these requirements is a new system design based on off-the-shelf components such as blue and green light emitting diodes (LEDs). This is due to the fact that LEDs offer solutions characterized by low cost, high efficiency, reliability and compactness. However, there are some challenges to be met when incorporating LEDs as part of the optical transmitter, such as low modulation rates and non linearity. In this paper, we review the main challenges facing the incorporation of LEDs as an integral part of underwater WC systems and propose some techniques to mitigate the LED limitations in order to achieve high data rate communication

  3. Obstacle avoidance locomotor tasks: adaptation, memory and skill transfer.

    PubMed

    Kloter, Evelyne; Dietz, Volker

    2012-05-01

    The aim of this study was to explore the neural basis of adaptation, memory and skill transfer during human stepping over obstacles. Whilst walking on a treadmill, subjects had to perform uni- and bilateral obstacle steps. Acoustic feedback information about foot clearance was provided. Non-noxious electrical stimuli were applied to the right tibial nerve during the mid-stance phase of the right leg, i.e. 'prior' to the right or 'during' the left leg swing over the obstacle. The electromyogram (EMG) responses evoked by these stimuli in arm and leg muscles are known to reflect the neural coordination during normal and obstacle steps. The leading and trailing legs rapidly adapted foot clearance during obstacle steps with small further changes when the same obstacle condition was repeated. This adaptation was associated with a corresponding decrease in arm and leg muscle reflex EMG responses. Arm (but not leg) muscle EMG responses were greater when the stimulus was applied 'during' obstacle crossing by the left leg leading compared with stimulation 'prior' to right leg swing over the obstacle. A corresponding difference existed in arm muscle background EMG. The results indicate that, firstly, the somatosensory information gained by the performance and adaptation of uni- and bilateral obstacle stepping becomes transferred to the trailing leg in a context-specific manner. Secondly, EMG activity in arm and leg muscles parallels biomechanical adaptation of foot clearance. Thirdly, a consistently high EMG activity in the arm muscles during swing over the obstacle is required for equilibrium control. Thus, such a precision locomotor task is achieved by a context-specific, coordinated activation of arm and leg muscles for performance and equilibrium control that includes adaptation, memory and skill transfer.

  4. Genotypic structure of a Drosophila population for adult locomotor activity

    SciTech Connect

    Grechanyi, G.V.; Korzun, V.M.

    1995-01-01

    Analysis of the variation of adult locomotor activity in four samples taken at different times from a natural population of Drosophila melanogaster showed that the total variation of this trait is relatively stable in time and has a substantial genetic component. Genotypic structure of the population for locomotor activity is characterized by the presence of large groups of genotypes with high and low values of this trait. A possible explanation for the presence of such groups in a population is cyclic density-dependent selection.

  5. Dynamics modeling and simulation of autonomous underwater vehicles with appendages

    NASA Astrophysics Data System (ADS)

    Su, Yumin; Zhao, Jinxin; Cao, Jian; Zhang, Guocheng

    2013-03-01

    To provide a simulation system platform for designing and debugging a small autonomous underwater vehicle's (AUV) motion controller, a six-degree of freedom (6-DOF) dynamic model for AUV controlled by thruster and fins with appendages is examined. Based on the dynamic model, a simulation system for the AUV's motion is established. The different kinds of typical motions are simulated to analyze the motion performance and the maneuverability of the AUV. In order to evaluate the influences of appendages on the motion performance of the AUV, simulations of the AUV with and without appendages are performed and compared. The results demonstrate the AUV has good maneuverability with and without appendages.

  6. Underwater Acoustic Wireless Sensor Networks: Advances and Future Trends in Physical, MAC and Routing Layers

    PubMed Central

    Climent, Salvador; Sanchez, Antonio; Capella, Juan Vicente; Meratnia, Nirvana; Serrano, Juan Jose

    2014-01-01

    This survey aims to provide a comprehensive overview of the current research on underwater wireless sensor networks, focusing on the lower layers of the communication stack, and envisions future trends and challenges. It analyzes the current state-of-the-art on the physical, medium access control and routing layers. It summarizes their security threads and surveys the currently proposed studies. Current envisioned niches for further advances in underwater networks research range from efficient, low-power algorithms and modulations to intelligent, energy-aware routing and medium access control protocols. PMID:24399155

  7. The effects of locomotor-respiratory coupling on the pattern of breathing in horses.

    PubMed Central

    Lafortuna, C L; Reinach, E; Saibene, F

    1996-01-01

    1. To investigate the effect of locomotor activity on the pattern of breathing in quadrupeds, ventilatory response was studied in four healthy horses during horizontal and inclined (7%) treadmill exercise at different velocities (1.4-6.9 m s(-1)) and during chemical stimulation with a rebreathing method. Stride frequency (f(s)) and locomotor-respiratory coupling (LRC) were also simultaneously determined by means of video recordings synchronized with respiratory events. 2. Tidal volume (V(T)) was positively correlated with pulmonary ventilation (V(E)) but significantly different linear regression equations were found between the experimental conditions (P < 0.0001), since the chemical hyperventilation was mainly due to increases in V(T), whereas the major contribution to exercise hyperpnoea came from changes in respiratory frequency (f(R)). 3. The average f(R) at each exercise level was not significantly different from f(S), although there was not always a tight 1:1 LRC. At constant speeds, f(S) was independent of the treadmill slope and hence the greater V(E) during inclined exercise was due to increased V(T). 4. At any ventilatory level, the differences in breathing patterns between locomotion and rebreathing or locomotion at different slopes derived from different set points of the inspiratory off-switch mechanism. 5. The percentage of single breaths entrained with locomotor rhythm rose progressively and significantly with treadmill speed (P < 0.0001) up to a 1:1 LRC and was significantly affected by treadmill slope (P < 0.001). 6. A LRC of 1:1 was systematically observed at canter (10 out of 10 trials) and sometimes at trot (5 out of 14) and it entailed (i) a 4- to 5-fold reduction in both V(T) and f(R) variability, and (ii) a gait-specific phase locking of inspiratory onset during the locomotor cycle. 7. It is concluded that different patterns of breathing are employed during locomotion and rebreathing due to the interference between locomotor and respiratory

  8. Biological Response to the Dynamic Spectral-Polarized Underwater Light Field

    DTIC Science & Technology

    2009-01-01

    2) Quantify the biological response in fish and cephalopods to these dynamic underwater optical environments (3) Identify the internal...controls and structural mechanisms that coordinate the camouflage response in fish and cephalopods APPROACH Our first aim is to measure and model...response (Cummings). Through these approaches we will characterize the internal control features regulating camouflage in both fish and cephalopods

  9. Plasticity of connections underlying locomotor recovery after central and/or peripheral lesions in the adult mammals

    PubMed Central

    Rossignol, Serge

    2006-01-01

    This review discusses some aspects of plasticity of connections after spinal injury in adult animal models as a basis for functional recovery of locomotion. After reviewing some pitfalls that must be avoided when claiming functional recovery and the importance of a conceptual framework for the control of locomotion, locomotor recovery after spinal lesions, mainly in cats, is summarized. It is concluded that recovery is partly due to plastic changes within the existing spinal locomotor networks. Locomotor training appears to change the excitability of simple reflex pathways as well as more complex circuitry. The spinal cord possesses an intrinsic capacity to adapt to lesions of central tracts or peripheral nerves but, as a rule, adaptation to lesions entails changes at both spinal and supraspinal levels. A brief summary of the spinal capacity of the rat, mouse and human to express spinal locomotor patterns is given, indicating that the concepts derived mainly from work in the cat extend to other adult mammals. It is hoped that some of the issues presented will help to evaluate how plasticity of existing connections may combine with and potentiate treatments designed to promote regeneration to optimize remaining motor functions. PMID:16939980

  10. The pars intercerebralis as a modulator of locomotor rhythms and feeding in the American cockroach, Periplaneta americana.

    PubMed

    Matsui, Takaaki; Matsumoto, Tomohisa; Ichihara, Naoyuki; Sakai, Tsubasa; Satake, Honoo; Watari, Yasuhiko; Takeda, Makio

    2009-03-23

    It has been shown that in orthopteran insects each of the optic lobes (OLs) contains a circadian pacemaker controlling locomotor activity and that the pars intercerebralis (PI) modifies the activity level. However, the present study showed Period protein-like immunoreactivity (PER-ir) in the PI and dorsolateral protocerebrum (DL) as well as in the OLs in the American cockroach, Periplaneta americana, which raised the possibility that the PI or DL could be a clock element. Therefore, we removed the PI or DL surgically and observed the effects on locomotor rhythms and feeding behavior. In constant darkness (DD), cockroaches with an ablated PI (PIX-DD) showed arrhythmicity in locomotion and a massive increase in food consumption that led to increased body length and weight, while PIX cockroaches reared under LD 12:12 (PIX-LD) and the sham-treated cockroaches in DD (CNT-DD) showed rhythmicity and no increase in food consumption. Statistical analysis showed that arrhythmicity was not accompanied by hyperactivity, suggesting that the PI is involved in the regulation of locomotor activity and feeding in DD. The activities of alpha-amylase and proteases were found to be markedly elevated in the midgut of PIX-DD cockroaches but not in PIX-LD cockroaches. Taken together, these results indicate that the PI modulates locomotor rhythms and feeding behavior of cockroaches in a light-dependent manner. The PI and the OL may regulate circadian rhythms and feeding via distinct pathways.

  11. Energy shaping and dissipation: Underwater vehicle stabilization using internal rotors

    NASA Astrophysics Data System (ADS)

    Woolsey, Craig Arthur

    This dissertation concerns nonlinear feedback stabilization of mechanical systems using energy-based methods. Nonlinear techniques are appealing because they can yield large regions of attraction for feedback-stabilized equilibria. Energy-based methods are particularly attractive for mechanical systems because these methods preserve a physical view of a system's dynamics and because they yield Lyapunov functions. For conservative systems, proof of stability typically requires the existence of a Lyapunov function. For systems with damping, Lyapunov functions can be used to design feedback dissipation to ensure or enhance asymptotic stability and to obtain more global conclusions. Both as a case study of a particular control methodology and as a practical contribution in the area of underwater vehicle control, we consider stabilization of an underwater vehicle using internal rotors as actuators. The methodology used to develop stabilizing control laws consists of three steps. The first step involves shaping the kinetic energy of the conservative dynamics. For the underwater vehicle, the control term in this step may be interpreted as modifying the system inertia. In the second step, feedback dissipation is designed based on a Lyapunov function developed in the first step. In the third step, it is verified that the effect of external damping due to viscous forces does not destroy the stability results. This method is applied first to a vehicle whose centers of gravity and buoyancy coincide and then to a vehicle with noncoincident centers of gravity and buoyancy. The method of controlled Lagrangians, developed in recent years, is a generalization of the idea of kinetic energy shaping. The method applies to underactuated mechanical systems (systems with more degrees of freedom than independent actuators). Motivated by the results of the investigation into the effect of external damping on an underwater vehicle with internal rotors, we study the effect of damping on more

  12. Haptic proprioception in a virtual locomotor task.

    PubMed

    Karunakaran, Kiran; Abbruzzese, Kevin; Xu, Hao; Ehrenberg, Naphtaly; Foulds, Richard

    2014-01-01

    Normal gait needs both proprioceptive and visual feedback to the nervous system to effectively control the rhythmicity of motor movement. Current preprogrammed exoskeletons provide only visual feedback with no user control over the foot trajectory. We propose an intuitive controller where hand trajectories are mapped to control contralateral foot movement. Our study shows that proprioceptive feedback provided to the users hand in addition to visual feedback result in better control during virtual ambulation than visual feedback alone. Hand trajectories resembled normal foot trajectories when both proprioceptive and visual feedback was present. Our study concludes that haptic feedback is essential for both temporal and spatial aspects of motor control in rhythmic movements.

  13. General and Specific Strategies Used to Facilitate Locomotor Maneuvers

    PubMed Central

    Wu, Mengnan; Matsubara, Jesse H.; Gordon, Keith E.

    2015-01-01

    People make anticipatory changes in gait patterns prior to initiating a rapid change of direction. How they prepare will change based on their knowledge of the maneuver. To investigate specific and general strategies used to facilitate locomotor maneuvers, we manipulated subjects’ ability to anticipate the direction of an upcoming lateral “lane-change” maneuver. To examine specific anticipatory adjustments, we observed the four steps immediately preceding a maneuver that subjects were instructed to perform at a known time in a known direction. We hypothesized that to facilitate a specific change of direction, subjects would proactively decrease margin of stability in the future direction of travel. Our results support this hypothesis: subjects significantly decreased lateral margin of stability by 69% on the side ipsilateral to the maneuver during only the step immediately preceding the maneuver. This gait adaptation may have improved energetic efficiency and simplified the control of the maneuver. To examine general anticipatory adjustments, we observed the two steps immediately preceding the instant when subjects received information about the direction of the maneuver. When the maneuver direction was unknown, we hypothesized that subjects would make general anticipatory adjustments that would improve their ability to actively initiate a maneuver in multiple directions. This second hypothesis was partially supported as subjects increased step width and stance phase hip flexion during these anticipatory steps. These modifications may have improved subjects’ ability to generate forces in multiple directions and maintain equilibrium during the onset and execution of the rapid maneuver. However, adapting these general anticipatory strategies likely incurred an additional energetic cost. PMID:26167931

  14. Underwater tunable organ-pipe sound source.

    PubMed

    Morozov, Andrey K; Webb, Douglas C

    2007-08-01

    A highly efficient frequency-controlled sound source based on a tunable high-Q underwater acoustic resonator is described. The required spectrum width was achieved by transmitting a linear frequency-modulated signal and simultaneously tuning the resonance frequency, keeping the sound source in resonance at the instantaneous frequency of the signal transmitted. Such sound sources have applications in ocean-acoustic tomography and deep-penetration seismic tomography. Mathematical analysis and numerical simulation show the Helmholtz resonator's ability for instant resonant frequency switching and quick adjustment of its resonant frequency to the instantaneous frequency signal. The concept of a quick frequency adjustment filter is considered. The discussion includes the simplest lumped resonant source as well as the complicated distributed system of a tunable organ pipe. A numerical model of the tunable organ pipe is shown to have a form similar to a transmission line segment. This provides a general form for the principal results, which can be applied to tunable resonators of a different physical nature. The numerical simulation shows that the "state-switched" concept also works in the high-Q tunable organ pipe, and the speed of frequency sweeping in a high-Q tunable organ pipe is analyzed. The simulation results were applied to a projector design for ocean-acoustic tomography.

  15. Acoustic communications and autonomous underwater vehicles

    NASA Astrophysics Data System (ADS)

    Freitag, Lee; Grund, Matthew; Preisig, James; Stojanovic, Milica

    2004-05-01

    Acoustic communications systems used on autonomous underwater vehicles (AUVs) provide supervisory control, access to real-time data, and also allow multiple vehicles to cooperate in undertaking adaptive sampling missions. However, the use of acoustic systems on AUVs presents special challenges because of limited space for optimal placement of transducers, and potential conflicts with other acoustic systems such as side-scan sonars and transponders. In addition, radiated and structure-borne acoustic interference from thrusters and actuators reduces the sensitivity of on-board receivers. Recent work in acoustic communications and AUVs has included combining some navigation functions into communications equipment, development of operating modes that remove conflicts between different subsystems, design of vehicle components to avoid or remove interference, and other approaches to improving performance. While these efforts have been successful for specific installations, many challenges remain. This talk addresses problems and solutions for supervised and completely autonomous multi-vehicle communications to support complex AUV missions. Also presented are recent results which demonstrate that acoustic communications can be used successfully on a variety of AUV platforms for many different applications. [Work supported by ONR.

  16. Human Injury Criteria for Underwater Blasts

    PubMed Central

    Lance, Rachel M.; Capehart, Bruce; Kadro, Omar; Bass, Cameron R.

    2015-01-01

    Underwater blasts propagate further and injure more readily than equivalent air blasts. Development of effective personal protection and countermeasures, however, requires knowledge of the currently unknown human tolerance to underwater blast. Current guidelines for prevention of underwater blast injury are not based on any organized injury risk assessment, human data or experimental data. The goal of this study was to derive injury risk assessments for underwater blast using well-characterized human underwater blast exposures in the open literature. The human injury dataset was compiled using 34 case reports on underwater blast exposure to 475 personnel, dating as early as 1916. Using severity ratings, computational reconstructions of the blasts, and survival information from a final set of 262 human exposures, injury risk models were developed for both injury severity and risk of fatality as functions of blast impulse and blast peak overpressure. Based on these human data, we found that the 50% risk of fatality from underwater blast occurred at 302±16 kPa-ms impulse. Conservatively, there is a 20% risk of pulmonary injury at a kilometer from a 20 kg charge. From a clinical point of view, this new injury risk model emphasizes the large distances possible for potential pulmonary and gut injuries in water compared with air. This risk value is the first impulse-based fatality risk calculated from human data. The large-scale inconsistency between the blast exposures in the case reports and the guidelines available in the literature prior to this study further underscored the need for this new guideline derived from the unique dataset of actual injuries in this study. PMID:26606655

  17. Locomotor Experience and Use of Social Information Are Posture Specific

    ERIC Educational Resources Information Center

    Adolph, Karen E.; Tamis-LeMonda, Catherine S.; Ishak, Shaziela; Karasik, Lana B.; Lobo, Sharon A.

    2008-01-01

    The authors examined the effects of locomotor experience on infants' perceptual judgments in a potentially risky situation--descending steep and shallow slopes--while manipulating social incentives to determine where perceptual judgments are most malleable. Twelve-month-old experienced crawlers and novice walkers were tested on an adjustable…

  18. Limits to human locomotor performance: phylogenetic origins and comparative perspectives.

    PubMed

    Dudley, R

    2001-09-01

    Studies of human exercise physiology have been conducted from a largely ahistorical perspective. This approach usefully elucidates proximate limits to locomotor performance, but ignores potential sources of biomechanical and physiological variation that derive from adaptation to ancestral environments. Phylogenetic reconstruction suggests that multiple hominoid lineages, including that leading to Homo sapiens, evolved in African highlands at altitudes of 1000-2000 m. The evolution of human locomotor physiology therefore occurred under conditions of hypobaric hypoxia. In contrast to present-day humans running on treadmills or exercising in otherwise rectilinear trajectories, ancestral patterns of hominid locomotion probably involved intermittent knuckle-walking over variable terrain, occasional bouts of arboreality and an evolving capacity for bipedalism. All such factors represent potential axes of locomotor variation at present unstudied in extant hominoid taxa. As with humans, hummingbirds evolved in mid-montane contexts but pose an extreme contrast with respect to body size, locomotor mode and metabolic capacity. Substantial biomechanical and physiological challenges are associated with flight in hypobaria. Nonetheless, hummingbird lineages demonstrate a progressive invasion of higher elevations and a remarkable tolerance to hypoxia during hovering. Upregulation of aerobic capacity and parallel resistance to hypoxia may represent coupled evolutionary adaptations to flight under high-altitude conditions.

  19. DRUG EFFECTS ON THE LOCOMOTOR ACTIVITY OF LARVAL ZEBRAFISH.

    EPA Science Inventory

    As part of an effort to develop a rapid in vivo screen for EPA’s prioritization of toxic chemicals, we have begun to characterize the locomotor activity of zebrafish (Danio rerio) larvae and the effects of prototype drugs. Zebrafish larvae (6-7 days post-fertilization) were indiv...

  20. Acute Neuroactive Drug Exposures alter Locomotor Activity in Larval Zebrafish

    EPA Science Inventory

    As part of the development of a rapid in vivo screen for prioritization of toxic chemicals, we have begun to characterize the locomotor activity of zebrafish (Danio rerio) larvae by assessing the acute effects of prototypic drugs that act on the central nervous system. Initially,...

  1. Unraveling a locomotor network, many neurons at a time.

    PubMed

    Brownstone, Robert M; Stifani, Nicolas

    2015-04-08

    In this issue of Neuron, Bruno et al. (2015) use large-scale recordings in Aplysia, and apply novel dimensionality-reduction techniques to define dynamical building blocks involved in locomotor behavior. These techniques open new avenues to the study of neuronal networks.

  2. A Model of Locomotor-Respiratory Coupling in Quadrupeds

    ERIC Educational Resources Information Center

    Giuliodori,, Mauricio J.; Lujan, Heidi L.; Briggs, Whitney S.; DiCarlo, Stephen E.

    2009-01-01

    Locomotion and respiration are not independent phenomena in running mammals because locomotion and respiration both rely on cyclic movements of the ribs, sternum, and associated musculature. Thus, constraints are imposed on locomotor and respiratory function by virtue of their linkage. Specifically, locomotion imposes mechanical constraints on…

  3. Acute neuroactive drug exposures alter locomotor activity in larval zebrafish

    EPA Science Inventory

    In an effort to develop a rapid in vivo screen for EPA's prioritization of toxic chemicals, we are characterizing the locomotor activity of zebrafish (Danio rerio) larvae after exposure to prototypic drugs that act on the central nervous system. MPTP (1-methyl-4phenyl- 1 ,2,3,6-...

  4. Multivariable Control of an Underwater Vehicle

    DTIC Science & Technology

    1984-05-01

    Response of the Twenty Knot Compensated Nonlinear Model 77 b5 TIME 3b 6b W 12 E &0 2 0 " 7 6 .o0 9o .20 ISO Io 210 21*0 270 300 TIME 3 0 30 so 90 120 I, S...d - ,- - ’a. C" 3 60 90 120 1 SO IGO 210 20 270 300 TIME o0 so 30 G’ 90 12 0 ISO IGO 210 240 070 30 TIME 0 s ], M 0 IGO...12 E o 10 1 4 7 TIM 30 60 so 120 ISO 160 210 260 270 300 TIME 0 30 so so 120 ISO ISO 210 26O 270 300 TI ME o0.. " " " ’ . . . o 3 10 60 12 0 10 I. ,O

  5. Acoustic Based Tactical Control of Underwater Vehicles

    DTIC Science & Technology

    2003-06-01

    Fundamental to information theory, only the first two are strictly coding processes. While the ultimate goal is for autonomous vehicles to independently use...code rate (explained later) will result in a four symbol string. The two data bit strings have four possible sequences but the four independent ...ltiplication with a generating m x, G nearly independent basis vectors of length n. The input is an as a “code word.” The number of distinct

  6. Activation of Neurotensin Receptor Type 1 Attenuates Locomotor Activity

    PubMed Central

    Vadnie, Chelsea A.; Hinton, David J.; Choi, Sun; Choi, YuBin; Ruby, Christina L.; Oliveros, Alfredo; Prieto, Miguel L.; Park, Jun Hyun; Choi, Doo-Sup

    2014-01-01

    Intracerebroventricular administration of neurotensin (NT) suppresses locomotor activity. However, the brain regions that mediate the locomotor depressant effect of NT and receptor subtype-specific mechanisms involved are unclear. Using a brain-penetrating, selective NT receptor type 1 (NTS1) agonist PD149163, we investigated the effect of systemic and brain region-specific NTS1 activation on locomotor activity. Systemic administration of PD149163 attenuated the locomotor activity of C57BL/6J mice both in a novel environment and in their homecage. However, mice developed tolerance to the hypolocomotor effect of PD149163 (0.1 mg/kg, i.p.). Since NTS1 is known to modulate dopaminergic signaling, we examined whether PD149163 blocks dopamine receptor-mediated hyperactivity. Pretreatment with PD149163 (0.1 or 0.05 mg/kg, i.p.) inhibited D2R agonist bromocriptine (8 mg/kg, i.p.)-mediated hyperactivity. D1R agonist SKF81297 (8 mg/kg, i.p.)-induced hyperlocomotion was only inhibited by 0.1 mg/kg of PD149163. Since the nucleus accumbens (NAc) and medial prefrontal cortex (mPFC) have been implicated in the behavioral effects of NT, we examined whether microinjection of PD149163 into these regions reduces locomotion. Microinjection of PD149163 (2 pmol) into the NAc, but not the mPFC suppressed locomotor activity. In summary, our results indicate that systemic and intra-NAc activation of NTS1 is sufficient to reduce locomotion and NTS1 activation inhibits D2R-mediated hyperactivity. Our study will be helpful to identify pharmacological factors and a possible therapeutic window for NTS1-targeted therapies for movement disorders. PMID:24929110

  7. Modulation of spontaneous locomotor and respiratory drives to hindlimb motoneurons temporally related to sympathetic drives as revealed by Mayer waves

    PubMed Central

    Wienecke, Jacob; Enríquez Denton, Manuel; Stecina, Katinka; Kirkwood, Peter A.; Hultborn, Hans

    2015-01-01

    In this study we investigated how the networks mediating respiratory and locomotor drives to lumbar motoneurons interact and how this interaction is modulated in relation to periodic variations in blood pressure (Mayer waves). Seven decerebrate cats, under neuromuscular blockade, were used to study central respiratory drive potentials (CRDPs, usually enhanced by added CO2) and spontaneously occurring locomotor drive potentials (LDPs) in hindlimb motoneurons, together with hindlimb and phrenic nerve discharges. In four of the cats both drives and their voltage-dependent amplification were absent or modest, but in the other three, one or other of these drives was common and the voltage-dependent amplification was frequently strong. Moreover, in these three cats the blood pressure showed marked periodic variation (Mayer waves), with a slow rate (periods 9–104 s, mean 39 ± 17 SD). Profound modulation, synchronized with the Mayer waves was seen in the occurrence and/or in the amplification of the CRDPs or LDPs. In one animal, where CRDPs were present in most cells and the amplification was strong, the CRDP consistently triggered sustained plateaux at one phase of the Mayer wave cycle. In the other two animals, LDPs were common, and the occurrence of the locomotor drive was gated by the Mayer wave cycle, sometimes in alternation with the respiratory drive. Other interactions between the two drives involved respiration providing leading events, including co-activation of flexors and extensors during post-inspiration or a locomotor drive gated or sometimes entrained by respiration. We conclude that the respiratory drive in hindlimb motoneurons is transmitted via elements of the locomotor central pattern generator. The rapid modulation related to Mayer waves suggests the existence of a more direct and specific descending modulatory control than has previously been demonstrated. PMID:25713515

  8. Down-regulation of Decapping Protein 2 mediates chronic nicotine exposure-induced locomotor hyperactivity in Drosophila.

    PubMed

    Ren, Jing; Sun, Jinghan; Zhang, Yunpeng; Liu, Tong; Ren, Qingzhong; Li, Yan; Guo, Aike

    2012-01-01

    Long-term tobacco use causes nicotine dependence via the regulation of a wide range of genes and is accompanied by various health problems. Studies in mammalian systems have revealed some key factors involved in the effects of nicotine, including nicotinic acetylcholine receptors (nAChRs), dopamine and other neurotransmitters. Nevertheless, the signaling pathways that link nicotine-induced molecular and behavioral modifications remain elusive. Utilizing a chronic nicotine administration paradigm, we found that adult male fruit flies exhibited locomotor hyperactivity after three consecutive days of nicotine exposure, while nicotine-naive flies did not. Strikingly, this chronic nicotine-induced locomotor hyperactivity (cNILH) was abolished in Decapping Protein 2 or 1 (Dcp2 or Dcp1) -deficient flies, while only Dcp2-deficient flies exhibited higher basal levels of locomotor activity than controls. These results indicate that Dcp2 plays a critical role in the response to chronic nicotine exposure. Moreover, the messenger RNA (mRNA) level of Dcp2 in the fly head was suppressed by chronic nicotine treatment, and up-regulation of Dcp2 expression in the nervous system blocked cNILH. These results indicate that down-regulation of Dcp2 mediates chronic nicotine-exposure-induced locomotor hyperactivity in Drosophila. The decapping proteins play a major role in mRNA degradation; however, their function in the nervous system has rarely been investigated. Our findings reveal a significant role for the mRNA decapping pathway in developing locomotor hyperactivity in response to chronic nicotine exposure and identify Dcp2 as a potential candidate for future research on nicotine dependence.

  9. Underwater Calibration of Dome Port Pressure Housings

    NASA Astrophysics Data System (ADS)

    Nocerino, E.; Menna, F.; Fassi, F.; Remondino, F.

    2016-03-01

    Underwater photogrammetry using consumer grade photographic equipment can be feasible for different applications, e.g. archaeology, biology, industrial inspections, etc. The use of a camera underwater can be very different from its terrestrial use due to the optical phenomena involved. The presence of the water and camera pressure housing in front of the camera act as additional optical elements. Spherical dome ports are difficult to manufacture and consequently expensive but at the same time they are the most useful for underwater photogrammetry as they keep the main geometric characteristics of the lens unchanged. Nevertheless, the manufacturing and alignment of dome port pressure housing components can be the source of unexpected changes of radial and decentring distortion, source of systematic errors that can influence the final 3D measurements. The paper provides a brief introduction of underwater optical phenomena involved in underwater photography, then presents the main differences between flat and dome ports to finally discuss the effect of manufacturing on 3D measurements in two case studies.

  10. Omnidirectional underwater camera design and calibration.

    PubMed

    Bosch, Josep; Gracias, Nuno; Ridao, Pere; Ribas, David

    2015-03-12

    This paper presents the development of an underwater omnidirectional multi-camera system (OMS) based on a commercially available six-camera system, originally designed for land applications. A full calibration method is presented for the estimation of both the intrinsic and extrinsic parameters, which is able to cope with wide-angle lenses and non-overlapping cameras simultaneously. This method is valid for any OMS in both land or water applications. For underwater use, a customized housing is required, which often leads to strong image distortion due to refraction among the different media. This phenomena makes the basic pinhole camera model invalid for underwater cameras, especially when using wide-angle lenses, and requires the explicit modeling of the individual optical rays. To address this problem, a ray tracing approach has been adopted to create a field-of-view (FOV) simulator for underwater cameras. The simulator allows for the testing of different housing geometries and optics for the cameras to ensure a complete hemisphere coverage in underwater operation. This paper describes the design and testing of a compact custom housing for a commercial off-the-shelf OMS camera (Ladybug 3) and presents the first results of its use. A proposed three-stage calibration process allows for the estimation of all of the relevant camera parameters. Experimental results are presented, which illustrate the performance of the calibration method and validate the approach.

  11. Omnidirectional Underwater Camera Design and Calibration

    PubMed Central

    Bosch, Josep; Gracias, Nuno; Ridao, Pere; Ribas, David

    2015-01-01

    This paper presents the development of an underwater omnidirectional multi-camera system (OMS) based on a commercially available six-camera system, originally designed for land applications. A full calibration method is presented for the estimation of both the intrinsic and extrinsic parameters, which is able to cope with wide-angle lenses and non-overlapping cameras simultaneously. This method is valid for any OMS in both land or water applications. For underwater use, a customized housing is required, which often leads to strong image distortion due to refraction among the different media. This phenomena makes the basic pinhole camera model invalid for underwater cameras, especially when using wide-angle lenses, and requires the explicit modeling of the individual optical rays. To address this problem, a ray tracing approach has been adopted to create a field-of-view (FOV) simulator for underwater cameras. The simulator allows for the testing of different housing geometries and optics for the cameras to ensure a complete hemisphere coverage in underwater operation. This paper describes the design and testing of a compact custom housing for a commercial off-the-shelf OMS camera (Ladybug 3) and presents the first results of its use. A proposed three-stage calibration process allows for the estimation of all of the relevant camera parameters. Experimental results are presented, which illustrate the performance of the calibration method and validate the approach. PMID:25774707

  12. The spatial structure of underwater noise due to shipping activities in the Celtic Sea

    NASA Astrophysics Data System (ADS)

    Chen, Feng; Shapiro, Georgy; Thain, Richard

    2014-05-01

    Underwater noise is now classed as pollution alongside chemical pollution and marine litter (MSFD, 2012). Underwater noise from man-made sources arises from a number of sources including shipping activities. There are numerous examples of sound-induced effects recorded for various marine mammals, either in controlled situations, or opportunistically (MSFD-GES, 2012). Broad or narrow band continuous sounds, as well as pulses, have been documented to cause effects ranging from slight behaviour change, to activity disruption, avoidance or abandonment of preferred habitat (see Clark et al., 2009). Underwater ambient noise generated by shipping activities has increased significantly over the past decades (e.g. Mcdonald et al., 2006). Noise from shipping is a major contributor to the ambient noise levels in ocean, particularly at low (

  13. 20-meter underwater wireless optical communication link with 1.5 Gbps data rate.

    PubMed

    Shen, Chao; Guo, Yujian; Oubei, Hassan M; Ng, Tien Khee; Liu, Guangyu; Park, Ki-Hong; Ho, Kang-Ting; Alouini, Mohamed-Slim; Ooi, Boon S

    2016-10-31

    The video streaming, data transmission, and remote control in underwater call for high speed (Gbps) communication link with a long channel length (~10 meters). We present a compact and low power consumption underwater wireless optical communication (UWOC) system utilizing a 450-nm laser diode (LD) and a Si avalanche photodetector. With the LD operating at a driving current of 80 mA with an optical power of 51.3 mW, we demonstrated a high-speed UWOC link offering a data rate up to 2 Gbps over a 12-meter-long, and 1.5 Gbps over a record 20-meter-long underwater channel. The measured bit-error rate (BER) are 2.8 × 10-5, and 3.0 × 10-3, respectively, which pass well the forward error correction (FEC) criterion.

  14. Observer based output feedback tuning for underwater remotely operated vehicle based on linear quadratic performance

    NASA Astrophysics Data System (ADS)

    Aras, Mohd Shahrieel Mohd; Abdullah, Shahrum Shah; Kamarudin, Muhammad Nizam; Rahman, Ahmad Fadzli Nizam Abdul; Azis, Fadilah Abd; Jaafar, Hazriq Izzuan

    2015-05-01

    This paper describes the effectiveness of observer-based output feedback for Unmanned Underwater Vehicle (UUV) with Linear Quadratic Regulation (LQR) performance. Tuning of observer parameters is crucial for tracking purpose. Prior to tuning facility, the ranges of observer and LQR parameters are obtained via system output cum error. The validation of this technique using unmanned underwater vehicles called Remotely Operated Vehicle (ROV) modelling helps to improve steady state performance of system response. The ROV modeling is focused for depth control using ROV 1 developed by the Underwater Technology Research Group (UTeRG). The results are showing that this technique improves steady state performances in term of overshoot and settling time of the system response.

  15. Effects of Maternal Intravenous Nicotine Administration on Locomotor Behavior in Pre-Weanling Rats

    PubMed Central

    LeSage, Mark G.; Gustaf, Erianne; Dufek, Matthew B.; Pentel, Paul R.

    2007-01-01

    Maternal tobacco use is associated with adverse developmental outcomes in offspring, including hyperactivity. Animal studies attempting to model this phenomenon have primarily used continuous s.c. nicotine infusion as the method of nicotine administration, which does not model the intermittent bolus delivery of nicotine associated with smoking in humans. The purpose of the present experiment was to examine the locomotor activity of pre-weanling offspring of pregnant rats exposed to an i.v. nicotine dosing protocol that approximates the pattern of nicotine exposure in moderate to heavy smokers. Pregnant rats were administered an i.v. bolus of 0.03 mg/kg nicotine (N=13) or saline (N=10) every 14 min for 16 hr/day, resulting in a total daily dose of 2 mg/kg (base), from gestational day 4 to delivery. Pups from each litter were tested for spontaneous locomotor activity on postnatal days (PND) 19–21 and nicotine-induced locomotor activity on PND 22. Mean birth weight was significantly lower in nicotine-exposed pups compared to controls, but body weights were equivalent between groups by the time of behavioral testing. Mean total distance traveled, vertical counts, and stereotypy counts were lower on PND 19 in nicotine-exposed pups compared to controls, but only the difference in mean stereotypy counts was statistically significant. Within session analysis revealed that both distance traveled and stereotypy were significantly decreased in nicotine-exposed pups in the first five minutes of the session on PND 19. Total time spent in the center of the field was also lower in nicotine exposed pups. Nicotine-induced increases in activity on PND 22 did not differ according to gestational exposure. These findings demonstrate that prenatal nicotine exposure in a model that mimics the pattern of nicotine exposure from cigarette smoking in humans results in offspring that exhibit low birth weight and hypoactivity in a novel environment. PMID:17141848

  16. SBMAC: smart blocking MAC mechanism for variable UW-ASN (Underwater Acoustic Sensor Network) environment.

    PubMed

    Shin, Soo-Young; Namgung, Jung-Il; Park, Soo-Hyun

    2010-01-01

    In this paper, several MAC scheduling methods applicable to an underwater environment are proposed. Besides, a new marine communication system model was proposed to improve the reliability of the proposed SBMAC method. The scheme minimizes transmission of control frames except for data transmission and various transmission methods and ACK methods can be used together. Simulation models are set indices and analysis of the underwater environment is established to conduct reliable simulations. Consequently, the performance improvement of the proposed method is verified with respect to delay time, data transmission rate, memory utilization, energy efficiency, etc.

  17. 46 CFR 167.05-40 - Underwater survey.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Underwater survey. 167.05-40 Section 167.05-40 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS Definitions § 167.05-40 Underwater survey. Underwater survey means the examination of the vessel's...

  18. 46 CFR 167.05-40 - Underwater survey.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Underwater survey. 167.05-40 Section 167.05-40 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS Definitions § 167.05-40 Underwater survey. Underwater survey means the examination of the vessel's...

  19. 46 CFR 167.05-40 - Underwater survey.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Underwater survey. 167.05-40 Section 167.05-40 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS Definitions § 167.05-40 Underwater survey. Underwater survey means the examination of the vessel's...

  20. 46 CFR 167.05-40 - Underwater survey.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Underwater survey. 167.05-40 Section 167.05-40 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS Definitions § 167.05-40 Underwater survey. Underwater survey means the examination of the vessel's...

  1. 46 CFR 167.05-40 - Underwater survey.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Underwater survey. 167.05-40 Section 167.05-40 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS PUBLIC NAUTICAL SCHOOL SHIPS Definitions § 167.05-40 Underwater survey. Underwater survey means the examination of the vessel's...

  2. Progressively Communicating Rich Telemetry from Autonomous Underwater Vehicles via Relays

    DTIC Science & Technology

    2012-06-01

    2012-10 DOCTORAL DISSERTATION by Chris Murphy June 2012 Progressively Communicating Rich Telemetry from Autonomous Underwater Vehicles via Relays MIT...MIT/WHO I 2012-10 Progressively Communicating Rich Telemetry from Autonomous Underwater Vehicles via Relays by Chris Murphy Massachusetts...States Government. This thesis should be cited as: Chris Murphy, 2012. Progressively Communicating Rich Telemetry from Autonomous Underwater Vehicles

  3. Low-dose effect of ethanol on locomotor activity induced by activation of the mesolimbic system.

    PubMed

    Milton, G V; Randall, P K; Erickson, C K

    1995-06-01

    Four experiments were designed to study the ability of 0.5 g/kg ethanol (EtOH) intraperitoneally to modify locomotor activity induced by drugs that interact with different sites in the mesolimbic system (MLS) of male Sprague-Dawley rats. Locomotor activity was measured in a doughnut-shaped circular arena after various treatments. EtOH alone did not alter locomotor activity in any of the experiments. Amphetamine (AMP, intraperitoneally or intraaccumbens) increased locomotor activity in a dose-dependent manner, and the presence of EtOH attenuated AMP-induced locomotor activity. Bilateral infusion of GABAA antagonist picrotoxin (PIC) into the ventral tegmental area also increased locomotor activity in a dose-dependent manner, and the presence of EtOH attenuated PIC-induced locomotor activity. On the other hand, the interaction between bilateral infusion of mu-receptor agonist Tyr-D-Ala-Gly-NMe-Phe-Gly-ol (DAGO) and EtOH on locomotor activity is complex. The highest dose of DAGO that significantly increased locomotor activity was not affected by the presence of EtOH. But, with lower doses of DAGO that either had no effect or a small increase in locomotor activity, the combination of EtOH and DAGO increased and attenuated locomotor activity, respectively. Results from this study support our hypothesis that a low dose of EtOH that does not modify behavior can interact with neurotransmitter systems in the brain and modify drug-induced locomotor activity. Modification of this drug-induced locomotor activity by a low dose of EtOH is dependent on the rate of ongoing locomotor behavior induced by drug and the neurotransmitter substrate that the drug modified to induce locomotor behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

  4. A neurorobotic platform for locomotor prosthetic development in rats and mice

    NASA Astrophysics Data System (ADS)

    von Zitzewitz, Joachim; Asboth, Leonie; Fumeaux, Nicolas; Hasse, Alexander; Baud, Laetitia; Vallery, Heike; Courtine, Grégoire

    2016-04-01

    Objectives. We aimed to develop a robotic interface capable of providing finely-tuned, multidirectional trunk assistance adjusted in real-time during unconstrained locomotion in rats and mice. Approach. We interfaced a large-scale robotic structure actuated in four degrees of freedom to exchangeable attachment modules exhibiting selective compliance along distinct directions. This combination allowed high-precision force and torque control in multiple directions over a large workspace. We next designed a neurorobotic platform wherein real-time kinematics and physiological signals directly adjust robotic actuation and prosthetic actions. We tested the performance of this platform in both rats and mice with spinal cord injury. Main Results. Kinematic analyses showed that the robotic interface did not impede locomotor movements of lightweight mice that walked freely along paths with changing directions and height profiles. Personalized trunk assistance instantly enabled coordinated locomotion in mice and rats with severe hindlimb motor deficits. Closed-loop control of robotic actuation based on ongoing movement features enabled real-time control of electromyographic activity in anti-gravity muscles during locomotion. Significance. This neurorobotic platform will support the study of the mechanisms underlying the therapeutic effects of locomotor prosthetics and rehabilitation using high-resolution genetic tools in rodent models.

  5. Underwater photogrammetric theoretical equations and technique

    NASA Astrophysics Data System (ADS)

    Fan, Ya-bing; Huang, Guiping; Qin, Gui-qin; Chen, Zheng

    2011-12-01

    In order to have a high level of accuracy of measurement in underwater close-range photogrammetry, this article deals with a study of three varieties of model equations according to the way of imaging upon the water. First, the paper makes a careful analysis for the two varieties of theoretical equations and finds out that there are some serious limitations in practical application and has an in-depth study for the third model equation. Second, one special project for this measurement has designed correspondingly. Finally, one rigid antenna has been tested by underwater photogrammetry. The experimental results show that the precision of 3D coordinates measurement is 0.94mm, which validates the availability and operability in practical application with this third equation. It can satisfy the measurement requirements of refraction correction, improving levels of accuracy of underwater close-range photogrammetry, as well as strong antijamming and stabilization.

  6. Remotely operated submersible underwater suction apparatus

    DOEpatents

    Kristan, Louis L.

    1990-01-01

    A completely submersible, remotely operated underwater suction device for collection of irradiated materials in a nuclear pool is disclosed. The device includes a pump means for pumping water through the device, a filter means for capturing irradiated debris, remotely operated releasable connector means, a collection means and a means for remotely maneuvering the collection means. The components of the suction device may be changed and replaced underwater to take advantage of the excellent radiation shielding ability of water to thereby minimize exposure of personnel to radiation.

  7. Naloxone blocks ethanol-mediated appetitive conditioning and locomotor activation in adolescent rats.

    PubMed

    Pautassi, Ricardo Marcos; Nizhnikov, Michael E; Acevedo, María Belén; Spear, Norman E

    2011-01-01

    Age-related differences in ethanol sensitivity could put adolescents at risk for developing alcohol-related problems. Little information exists, however, about adolescent sensitivity to ethanol's appetitive effects and the neurobiological mechanisms underlying ethanol reinforcement during this developmental stage. The present study assessed the role of the opioid system in adolescent rats in an appetitive second-order schedule of ethanol reinforcement and ethanol-induced locomotor stimulation. On postnatal day 32 (PD32), animals were pretreated with the general opioid antagonist naloxone (0.0, 0.75, 1.50, or 2.5 mg/kg) and then given pairings of ethanol (0.0 or 2.0 g/kg, intragastrically) with intraoral pulses of water (conditioned stimulus 1 [CS₁], first-order conditioning phase). CS₁ delivery occurred 30-45 min after ethanol administration when the effect of ethanol was assumed to be appetitive. On PD33, adolescents were exposed to CS₁ (second-order conditioning phase) while in a chamber featuring distinctive exteroceptive cues (CS₂). Preference for CS₂ was then tested. Adolescents given CS₁-ethanol pairings exhibited greater preference for CS₂ than controls, indicating ethanol-mediated reinforcement, but only when not pretreated with naloxone. Blood alcohol levels during conditioning were not altered by naloxone. Experiment 2 revealed that ethanol-induced locomotor activation soon after administration, and naloxone dose-dependently suppressed this stimulating effect. The present study indicates that adolescent rats are sensitive to ethanol's reinforcing and locomotor-stimulating effects. Both effects of ethanol appear to be mediated by endogenous opioid system activation.

  8. NALOXONE BLOCKS ETHANOL-MEDIATED APPETITIVE CONDITIONING AND LOCOMOTOR ACTIVATION IN ADOLESCENT RATS

    PubMed Central

    Pautassi, Ricardo Marcos; Nizhnikov, Michael E.; Acevedo, María Belén; Spear, Norman E.

    2010-01-01

    Age-related differences in ethanol sensitivity could put adolescents at risk for developing alcohol-related problems. Little information exists, however, about adolescent sensitivity to ethanol's appetitive effects and the neurobiological mechanisms underlying ethanol reinforcement during this developmental stage. The present study assessed the role of the opioid system in adolescent rats in an appetitive second-order schedule of ethanol reinforcement and ethanol-induced locomotor stimulation. On postnatal day 32 (PD32), animals were pretreated with the general opioid antagonist naloxone (0.0, 0.75, 1.50, or 2.5 mg/kg) and then given pairings of ethanol (0.0 or 2.0 g/kg, intragastrically) with intraoral pulses of water (conditioned stimulus 1 [CS1], first-order conditioning phase). CS1 delivery occurred 30–45 min after ethanol administration when the effect of ethanol was assumed to be appetitive. On PD33, adolescents were exposed to CS1 (second-order conditioning phase) while in a chamber featuring distinctive exteroceptive cues (CS2). Preference for CS2 was then tested. Adolescents given CS1-ethanol pairings exhibited greater preference for CS2 than controls, indicating ethanol-mediated reinforcement, but only when not pretreated with naloxone. Blood alcohol levels during conditioning were not altered by naloxone. Experiment 2 revealed that ethanol induced locomotor activation soon after administration, and naloxone dose-dependently suppressed this stimulating effect. The present study indicates that adolescent rats are sensitive to ethanol's reinforcing and locomotor-stimulating effects. Both effects of ethanol appear to be mediated by endogenous opioid system activation. PMID:20708642

  9. Behavioral cross-sensitization between DOCA-induced sodium appetite and cocaine-induced locomotor behavior.

    PubMed

    Acerbo, Martin J; Johnson, Alan Kim

    2011-05-01

    Behavioral sensitization involves increases in the magnitude of a response to a stimulus after repeated exposures to the same response initiator. Administration of psychomotor stimulants and the induction of appetitive motivational states associated with natural reinforcers like sugar and salt are among experimental manipulations producing behavioral sensitization. In rats, repeated administration of the mineralocorticoid agonist deoxycorticosterone acetate (DOCA) initially induces incremental increases in daily hypertonic saline consumption (i.e., sensitization of sodium appetite) in spite of the retention of sodium. The present studies investigated whether sodium appetite sensitization induced by DOCA shares mechanisms similar to those of psychomotor stimulant-induced sensitization, and whether there is evidence for reciprocal cross-sensitization. In Experiments 1 and 3, rats received control or cocaine treatments to induce locomotor sensitization. A week later DOCA (or vehicle) was administered to generate a sodium appetite. Animals pretreated with cocaine showed a greater sodium appetite. In Experiment 2, the order of the putative sensitizing treatments was reversed. Rats first received either a series of DOCA or vehicle treatments either with or without access to saline and were later tested for sensitization of the locomotor response to cocaine. Animals pretreated with DOCA without access to saline showed greater locomotor responses to cocaine than animals receiving vehicle treatments. Together these experiments indicate that treatments generating a sustained salt appetite and producing cocaine-induced psychomotor responses show reciprocal behavioral cross-sensitization. The underlying mechanisms accounting for this relationship may be the fact that psychostimulants and an unresolved craving for sodium can act as potent stressors.

  10. Enhanced locomotor adaptation aftereffect in the “broken escalator” phenomenon using anodal tDCS

    PubMed Central

    Kaski, D.; Quadir, S.; Patel, M.; Yousif, N.

    2012-01-01

    The everyday experience of stepping onto a stationary escalator causes a stumble, despite our full awareness that the escalator is broken. In the laboratory, this “broken escalator” phenomenon is reproduced when subjects step onto an obviously stationary platform (AFTER trials) that was previously experienced as moving (MOVING trials) and attests to a process of motor adaptation. Given the critical role of M1 in upper limb motor adaptation and the potential for transcranial direct current stimulation (tDCS) to increase cortical excitability, we hypothesized that anodal tDCS over leg M1 and premotor cortices would increase the size and duration of the locomotor aftereffect. Thirty healthy volunteers received either sham or real tDCS (anodal bihemispheric tDCS; 2 mA for 15 min at rest) to induce excitatory effects over the primary motor and premotor cortex before walking onto the moving platform. The real tDCS group, compared with sham, displayed larger trunk sway and increased gait velocity in the first AFTER trial and a persistence of the trunk sway aftereffect into the second AFTER trial. We also used transcranial magnetic stimulation to probe changes in cortical leg excitability using different electrode montages and eyeblink conditioning, before and after tDCS, as well as simulating the current flow of tDCS on the human brain using a computational model of these different tDCS montages. Our data show that anodal tDCS induces excitability changes in lower limb motor cortex with resultant enhancement of locomotor adaptation aftereffects. These findings might encourage the use of tDCS over leg motor and premotor regions to improve locomotor control in patients with neurological gait disorders. PMID:22323638

  11. Developmental Deltamethrin Exposure Causes Persistent Changes in Dopaminergic Gene Expression, Neurochemistry, and Locomotor Activity in Zebrafish

    PubMed Central

    Kung, Tiffany S.; Richardson, Jason R.; Cooper, Keith R.; White, Lori A.

    2015-01-01

    Pyrethroids are commonly used insecticides that are considered to pose little risk to human health. However, there is an increasing concern that children are more susceptible to the adverse effects of pesticides. We used the zebrafish model to test the hypothesis that developmental exposure to low doses of the pyrethroid deltamethrin results in persistent alterations in dopaminergic gene expression, neurochemistry, and locomotor activity. Zebrafish embryos were treated with deltamethrin (0.25–0.50 μg/l), at concentrations below the LOAEL, during the embryonic period [3–72 h postfertilization (hpf)], after which transferred to fresh water until the larval stage (2-weeks postfertilization). Deltamethrin exposure resulted in decreased transcript levels of the D1 dopamine (DA) receptor (drd1) and increased levels of tyrosine hydroxylase at 72 hpf. The reduction in drd1 transcripts persisted to the larval stage and was associated with decreased D2 dopamine receptor transcripts. Larval fish, exposed developmentally to deltamethrin, had increased levels of homovanillic acid, a DA metabolite. Since the DA system is involved in locomotor activity, we measured the swim activity of larval fish following a transition to darkness. Developmental exposure to deltamethrin significantly increased larval swim activity which was attenuated by concomitant knockdown of the DA transporter. Acute exposure to methylphenidate, a DA transporter inhibitor, increased swim activity in control larva, while reducing swim activity in larva developmentally exposed to deltamethrin. Developmental exposure to deltamethrin causes locomotor deficits in larval zebrafish, which is likely mediated by dopaminergic dysfunction. This highlights the need to understand the persistent effects of low-dose neurotoxicant exposure during development. PMID:25912032

  12. Enkephalin contributes to the locomotor stimulating effects of 3,4-methylenedioxy-N-methylamphetamine.

    PubMed

    Compan, V; Scearce-Levie, K; Crosson, C; Daszuta, A; Hen, R

    2003-07-01

    3,4-methylenedioxy-N-methylamphetamine (MDMA, 'Ecstasy') is a potent inhibitor of serotonin uptake, which induces both an increase in locomotion and a decrease in exploratory activity in rodents. Serotonin 5-HT1B receptors, located on the terminals of striatal efferent neurons, have been suggested to mediate these motor effects of MDMA. Striatal neurons projecting to the globus pallidus contain met-enkephalin, whilst those projecting to the substantia nigra contain substance P. We therefore analysed the levels of both peptides using radioimmunocytochemistry after MDMA administration (10 mg/kg, 3 h) in wild-type and 5-HT1B receptor knockout mice. Our results demonstrate that MDMA induces a decrease in pallidal met-enkephalin immunolabelling in wild-type, but not in 5-HT1B receptor knockout mice. Similar results were obtained following treatment with the 5-HT1A/1B agonist RU24969 (5 mg/kg, 3 h), suggesting that activation of 5-HT1B receptors leads to a reduction in met-enkephalin levels in the globus pallidus. In contrast, MDMA had no effect on the nigral substance P levels. We have previously shown that both MDMA and RU24969 fail to stimulate locomotor activity in 5-HT1B receptor knockout mice. Our present data indicate that the opioid antagonist naloxone suppressed the locomotor effects of MDMA. This study is the first to demonstrate that Enk contributes to MDMA-induced increases in locomotor activity. Such an effect may be related to the 5-HT control of pallidal met-enkephalin levels via the 5-HT1B receptors.

  13. The time of day differently influences fatigue and locomotor activity: is body temperature a key factor?

    PubMed

    Machado, Frederico Sander Mansur; Rodovalho, Gisele Vieira; Coimbra, Cândido Celso

    2015-03-01

    The aim of this study was to verify the possible interactions between exercise capacity and spontaneous locomotor activity (SLA) during the oscillation of core body temperature (Tb) that occurs during the light/dark cycle. Wistar rats (n=11) were kept at an animal facility under a light/dark cycle of 14/10h at an ambient temperature of 23°C and water and food ad libitum. Initially, in order to characterize the daily oscillation in SLA and Tb of the rats, these parameters were continuously recorded for 24h using an implantable telemetric sensor (G2 E-Mitter). The animals were randomly assigned to two progressive exercise test protocols until fatigue during the beginning of light and dark-phases. Fatigue was defined as the moment rats could not keep pace with the treadmill. We assessed the time to fatigue, workload and Tb changes induced by exercise. Each test was separated by 3days. Our results showed that exercise capacity and heat storage were higher during the light-phase (p<0.05). In contrast, we observed that both SLA and Tb were higher during the dark-phase (p<0.01). Notably, the correlation analysis between the amount of SLA and the running capacity observed at each phase of the daily cycle revealed that, regardless of the time of the day, both types of locomotor physical activity have an important inherent component (r=0.864 and r=0.784, respectively, p<0.01) without a direct relationship between them. This finding provides further support for the existence of specific control mechanisms for each type of physical activity. In conclusion, our data indicate that the relationship between the body temperature and different types of physical activity might be affected by the light/dark cycle. These results mean that, although exercise performance and spontaneous locomotor activity are not directly associated, both are strongly influenced by daily cycles of light and dark.

  14. Design and implementation of omni-directional light source and receiving system used in underwater wireless optical communication

    NASA Astrophysics Data System (ADS)

    Rao, Jionghui; Yao, Wenming; Chen, Nannan

    2013-08-01

    Underwater wireless optical communication is a communication mode which uses light as an information carrier and water as transmission medium. As a result of the inherent characteristics of the light waves, underwater wireless optical communication has the advantages of high transmission rate, good security, and strong anti-interference ability. It is suitable for high-speed, short-range communication between underwater mobile vehicles. Underwater optical wireless communication system designed in this paper is composed of the omni-directional communication light source and the receiving system. In the omni-directional communication light source, the laser beams with small divergence angle of 532nm wavelength produced by modulated laser are expanded through a combination refraction-reflection solid and then obtain more than 2π space divergence angle. The paper use TRACEPRO simulation tool to help design a combination solid composed of the lens, conical reflector and parabolic reflector, and test in the air and underwater, the result shows that the effect is fine. Unlike in the air, light attenuation is heavy in the water and a large range of variations in light intensity at different distances appear during underwater optical communication. In order to overcome this problem, the paper use a small photomultiplier as the detection device, design the receiving system using the automatic gain control technique. Underwater wireless optical communication system designed in this paper has the characteristics of small size, low power dissipation and the omni-directional communication function, it is suitable for application in the UUV, AUV, Swimmer Delivery Vehicle (SDV) and other underwater mobile platform, it realizes point-to-point communications and point-to-multipoint communications.

  15. Decreased aggressive and locomotor behaviors in Betta splendens after exposure to fluoxetine.

    PubMed

    Kohlert, Jess G; Mangan, Brian P; Kodra, Christine; Drako, Linsay; Long, Emily; Simpson, Holly

    2012-02-01

    The failure of sewage treatment plants to remove pharmaceuticals such as fluoxetine from waste water has become a concern given that these products are being detected in the surface waters of many countries of the world. The effects of fluoxetine in sub-lethal doses on the neural systems and behaviors of aquatic life are worthy of investigation. This study investigated the effects of sub-lethal amounts fluoxetine dissolved in water on the aggressive and locomotor behaviors of 44 male Betta splendens. Fish treated with 705 microg/l of fluoxetine and 350 microg/l of fluoxetine generally demonstrated significant decreases in locomotion and number of aggressive attacks compared to 0 microg/l of fluoxetine (controls) on Days 11 and 19 of drug exposure and persisted for at least 13 days after removal of fluoxetine. Consistent with decreases in the number of aggressive attacks, there was a significant increase in aggression-response time to a perceived intruder for treated males on Days 11 and 19 and persisted for 6 days following removal of fluoxetine. However, the differences in aggressive and locomotor behaviors seen in the fluoxetine-treated groups were indistinguishable from controls three weeks following drug removal.

  16. Hindlimb Stretching Alters Locomotor Function Post-Spinal Cord Injury in the Adult Rat

    PubMed Central

    Caudle, Krista L.; Atkinson, Darryn A.; Brown, Edward H.; Donaldson, Katie; Seibt, Erik; Chea, Tim; Smith, Erin; Chung, Karianne; Shum-Siu, Alice; Cron, Courtney C.; Magnuson, David S. K.

    2014-01-01

    Background Stretching is a widely accepted standard-of-care therapy following spinal cord injury that has not been systematically studied in animal models. Objective To investigate the influence of a daily stretch-based physical therapy program on locomotor recovery in adult rats with moderate T9 contusive SCI. Methods A randomized treatment and control study of stretching in an animal model of acute spinal cord injury (SCI). Moderate spinal cord injuries were delivered with the NYU Impactor. Daily stretching (30 min./day, 5 days/wk for 8 wks) was provided by a team of animal handlers. Hindlimb function was assessed using the BBB Open Field Locomotor Scale and kinematically. Passive range-of-motion for each joint was determined weekly using a goniometer. Results Declines in hindlimb function during overground stepping were observed for the first 4 weeks. BBB scores improved weeks 5–10 but remained below the control group. Stretched animals had significant deficits in knee passive ROM starting at week 4 and for the duration of the study. Kinematic assessment showed decreased joint excursion during stepping that partially recovered beginning at week 5. Conclusion Stretch-based therapy significantly impaired functional recovery in adult rats with a moderate contusive SCI at T10. The negative impact on function was greatest acutely, but persisted even after the stretching ceased at 8 weeks post-injury. PMID:25106555

  17. The peacock train does not handicap cursorial locomotor performance

    PubMed Central

    Thavarajah, Nathan K.; Tickle, Peter G.; Nudds, Robert L.; Codd, Jonathan R.

    2016-01-01

    Exaggerated traits, like the peacock train, are recognized as classic examples of sexual selection. The evolution of sexual traits is often considered paradoxical as, although they enhance reproductive success, they are widely presumed to hinder movement and survival. Many exaggerated traits represent an additional mechanical load that must be carried by the animal and therefore may influence the metabolic cost of locomotion and constrain locomotor performance. Here we conducted respirometry experiments on peacocks and demonstrate that the exaggerated sexually selected train does not compromise locomotor performance in terms of the metabolic cost of locomotion and its kinematics. Indeed, peacocks with trains had a lower absolute and mass specific metabolic cost of locomotion. Our findings suggest that adaptations that mitigate any costs associated with exaggerated morphology are central in the evolution of sexually selected traits. PMID:27805067

  18. Multi-terrain locomotor interactions in flying snakes

    NASA Astrophysics Data System (ADS)

    Yeaton, Isaac; Baumgardner, Grant; Ross, Shane; Socha, John

    Arboreal snakes of the genus Chrysopelea are the only known snakes to glide. To execute aerial locomotion, a snake uses one of several stereotyped jumps from a tree into the air, while simultaneously flattening its body into an aerodynamically favorable shape. Large amplitude traveling waves are propagated posteriorly during the stable glide, while landing involves body wrapping, passive body compression, and energy absorption through compliance in the landing substrate to dissipate the accumulated kinetic energy from the glide. In all of these locomotor events, from interacting with cylindrical branches, falling through the air, grasping compliant tree branches and leaves, to landing on solid ground, snakes appropriate the same body morphology and perhaps the same basic neural mechanisms. Here we discuss our use of computational models and animal experiments to understand how flying snakes interact with and locomote on and through multiple media, potentially providing principles for legless locomotor designs. Supported by NSF 1351322.

  19. Micromachined fiber optic Fabry-Perot underwater acoustic probe

    NASA Astrophysics Data System (ADS)

    Wang, Fuyin; Shao, Zhengzheng; Hu, Zhengliang; Luo, Hong; Xie, Jiehui; Hu, Yongming

    2014-08-01

    One of the most important branches in the development trend of the traditional fiber optic physical sensor is the miniaturization of sensor structure. Miniature fiber optic sensor can realize point measurement, and then to develop sensor networks to achieve quasi-distributed or distributed sensing as well as line measurement to area monitoring, which will greatly extend the application area of fiber optic sensors. The development of MEMS technology brings a light path to address the problems brought by the procedure of sensor miniaturization. Sensors manufactured by MEMS technology possess the advantages of small volume, light weight, easy fabricated and low cost. In this paper, a fiber optic extrinsic Fabry-Perot interferometric underwater acoustic probe utilizing micromachined diaphragm collaborated with fiber optic technology and MEMS technology has been designed and implemented to actualize underwater acoustic sensing. Diaphragm with central embossment, where the embossment is used to anti-hydrostatic pressure which would largely deflect the diaphragm that induce interferometric fringe fading, has been made by double-sided etching of silicon on insulator. By bonding the acoustic-sensitive diaphragm as well as a cleaved fiber end in ferrule with an outer sleeve, an extrinsic Fabry-Perot interferometer has been constructed. The sensor has been interrogated by quadrature-point control method and tested in field-stable acoustic standing wave tube. Results have been shown that the recovered signal detected by the sensor coincided well with the corresponding transmitted signal and the sensitivity response was flat in frequency range from 10 Hz to 2kHz with the value about -154.6 dB re. 1/μPa. It has been manifest that the designed sensor could be used as an underwater acoustic probe.

  20. Development of Underwater Laser Cladding and Underwater Laser Seal Welding Techniques for Reactor Components (II)

    SciTech Connect

    Masataka Tamura; Shohei Kawano; Wataru Kouno; Yasushi Kanazawa

    2006-07-01

    Stress corrosion cracking (SCC) is one of the major reasons to reduce the reliability of aged reactor components. Toshiba has been developing underwater laser welding onto surface of the aged components as maintenance and repair techniques. Because most of the reactor internal components to apply this underwater laser welding technique have 3-dimensional shape, effect of welding positions and welded shapes are examined and presented in this report. (authors)

  1. Locomotor Experience and Use of Social Information Are Posture Specific

    PubMed Central

    Adolph, Karen E.; Tamis-LeMonda, Catherine S.; Ishak, Shaziela; Karasik, Lana B.; Lobo, Sharon A.

    2015-01-01

    The authors examined the effects of locomotor experience on infants’ perceptual judgments in a potentially risky situation—descending steep and shallow slopes—while manipulating social incentives to determine where perceptual judgments are most malleable. Twelve-month-old experienced crawlers and novice walkers were tested on an adjustable sloping walkway as their mothers encouraged and discouraged descent. A psychophysical procedure was used to estimate infants’ ability to crawl/walk down slopes, followed by test trials in which mothers encouraged and discouraged infants to crawl/walk down. Both locomotor experience and social incentives affected perceptual judgments. In the encourage condition, crawlers only attempted safe slopes within their abilities, but walkers repeatedly attempted impossibly risky slopes, replicating previous work. The discourage condition showed where judgments are most malleable. When mothers provided negative social incentives, crawlers occasionally avoided safe slopes, and walkers occasionally avoided the most extreme 50° increment, although they attempted to walk on more than half the trials. Findings indicate that both locomotor experience and social incentives play key roles in adaptive responding, but the benefits are specific to the posture that infants use for balance and locomotion. PMID:18999332

  2. Locomotor experience and use of social information are posture specific.

    PubMed

    Adolph, Karen E; Tamis-LeMonda, Catherine S; Ishak, Shaziela; Karasik, Lana B; Lobo, Sharon A

    2008-11-01

    The authors examined the effects of locomotor experience on infants' perceptual judgments in a potentially risky situation--descending steep and shallow slopes--while manipulating social incentives to determine where perceptual judgments are most malleable. Twelve-month-old experienced crawlers and novice walkers were tested on an adjustable sloping walkway as their mothers encouraged and discouraged descent. A psychophysical procedure was used to estimate infants' ability to crawl/walk down slopes, followed by test trials in which mothers encouraged and discouraged infants to crawl/walk down. Both locomotor experience and social incentives affected perceptual judgments. In the encourage condition, crawlers only attempted safe slopes within their abilities, but walkers repeatedly attempted impossibly risky slopes, replicating previous work. The discourage condition showed where judgments are most malleable. When mothers provided negative social incentives, crawlers occasionally avoided safe slopes, and walkers occasionally avoided the most extreme 50 degrees increment, although they attempted to walk on more than half the trials. Findings indicate that both locomotor experience and social incentives play key roles in adaptive responding, but the benefits are specific to the posture that infants use for balance and locomotion.

  3. Fluctuation-Driven Neural Dynamics Reproduce Drosophila Locomotor Patterns

    PubMed Central

    Cruchet, Steeve; Gustafson, Kyle; Benton, Richard; Floreano, Dario

    2015-01-01

    The neural mechanisms determining the timing of even simple actions, such as when to walk or rest, are largely mysterious. One intriguing, but untested, hypothesis posits a role for ongoing activity fluctuations in neurons of central action selection circuits that drive animal behavior from moment to moment. To examine how fluctuating activity can contribute to action timing, we paired high-resolution measurements of freely walking Drosophila melanogaster with data-driven neural network modeling and dynamical systems analysis. We generated fluctuation-driven network models whose outputs—locomotor bouts—matched those measured from sensory-deprived Drosophila. From these models, we identified those that could also reproduce a second, unrelated dataset: the complex time-course of odor-evoked walking for genetically diverse Drosophila strains. Dynamical models that best reproduced both Drosophila basal and odor-evoked locomotor patterns exhibited specific characteristics. First, ongoing fluctuations were required. In a stochastic resonance-like manner, these fluctuations allowed neural activity to escape stable equilibria and to exceed a threshold for locomotion. Second, odor-induced shifts of equilibria in these models caused a depression in locomotor frequency following olfactory stimulation. Our models predict that activity fluctuations in action selection circuits cause behavioral output to more closely match sensory drive and may therefore enhance navigation in complex sensory environments. Together these data reveal how simple neural dynamics, when coupled with activity fluctuations, can give rise to complex patterns of animal behavior. PMID:26600381

  4. Sigma ligand S14905 and locomotor activity in mice.

    PubMed

    Hascoet, M; Bourin, M; Payeur, R; Lombet, A; Peglion, J L

    1995-12-01

    The binding and locomotor profile of a new sigma ligand, S14905, (isobutyl-N-(1-indan-2yl-piperid-4-yl)N-methyl carbamate, furamate) was studied. The binding data revealed that S14905 has a high affinity for sigma receptors and very low affinity for both dopamine D1 and D2 receptors. We have demonstrated that this sigma ligand prevents the locomotor stimulation induced by morphine (32 and 64 mg/kg), cocaine (16 mg/kg), amphetamine (4 mg/kg) and adrafinil (32 mg/kg) at doses lower than those required to depress spontaneous locomotor activity. The antagonism observed in the present study seems to be more specific of morphine induced hyperlocomotion. The high affinity of this compound for sigma receptors makes it a good choice to study the role of this receptor in the CNS. In addition, S14905 does not directly block dopamine receptors but may modulate them in some manner, and would thus warrant further study as a potential atypical antipsychotic agent, and an antagonist for the hyperactivity induced by opiate drug.

  5. Amplified piezoelectric actuators: from aerospace to underwater applications

    NASA Astrophysics Data System (ADS)

    Bouchilloux, Philippe; Claeyssen, Frank; Le Letty, Ronan

    2004-07-01

    Aerospace and underwater applications typically require actuators capable of large displacements, precise positioning, and fast response times. To meet these requirements, several classes of actuators based on low-voltage piezoelectric materials have been developed, and, in the case of the Amplified Piezoelectric Actuators (APA series), space qualified. The APA actuators offer large displacements (up to 1mm), large deformations (up to 3%), and large forces (up to 1kN) at low electrical power. These actuators can withstand large external forces and have successfully passed severe qualification tests such as centrifugal accelerations and vibration forces encountered during space launch. Aerospace applications of APAs include scientific instrumentation, such as telescopes and microscopes, microsatellite propulsion valves, and structural vibration control. Aeronautical applications include active flap control in aircraft wings and helicopter blades. Underwater applications focus on the silencing of ships, the piezodiagnostic (NDE) of structural defects in pipelines and hulls, and guidance systems of unmanned vehicles. This paper reviews the use of piezoelectric actuators, in particular APAs, in such applications. Qualification results, when available, are presented and discussed.

  6. Towards Restoration of Missing Underwater Forests

    PubMed Central

    Vergés, Adriana; Coleman, Melinda A.; Steinberg, Peter D.

    2014-01-01

    Degradation of natural habitats due to urbanization is a major cause of biodiversity loss. Anthropogenic impacts can drive phase shifts from productive, complex ecosystems to less desirable, less diverse systems that provide fewer services. Macroalgae are the dominant habitat-forming organisms on temperate coastlines, providing habitat and food to entire communities. In recent decades, there has been a decline in macroalgal cover along some urbanised shorelines, leading to a shift from diverse algal forests to more simple turf algae or barren habitats. Phyllospora comosa, a major habitat forming macroalga in south-eastern Australia, has disappeared from the urban shores of Sydney. Its disappearance is coincident with heavy sewage outfall discharges along the metropolitan coast during 1970s and 1980s. Despite significant improvements in water-quality since that time, Phyllospora has not re-established. We experimentally transplanted adult Phyllospora into two rocky reefs in the Sydney metropolitan region to examine the model that Sydney is now suitable for the survival and recruitment of Phyllospora and thus assess the possibility of restoring Phyllospora back onto reefs where it was once abundant. Survival of transplanted individuals was high overall, but also spatially variable: at one site most individuals were grazed, while at the other site survival was similar to undisturbed algae and procedural controls. Transplanted algae reproduced and recruitment rates were higher than in natural populations at one experimental site, with high survival of new recruits after almost 18 months. Low supply and settlement success of propagules in the absence of adults and herbivory (in some places) emerge as three potential processes that may have been preventing natural re-establishment of this alga. Understanding of the processes and interactions that shape this system are necessary to provide ecologically sensible goals and the information needed to successfully restore

  7. KE Basin underwater visual fuel survey

    SciTech Connect

    Pitner, A.L.

    1995-02-01

    Results of an underwater video fuel survey in KE Basin using a high resolution camera system are presented. Quantitative and qualitative information on fuel degradation are given, and estimates of the total fraction of ruptured fuel elements are provided. Representative photographic illustrations showing the range of fuel conditions observed in the survey are included.

  8. Underwater Adhesives Retrofit Pipelines with Advanced Sensors

    NASA Technical Reports Server (NTRS)

    2015-01-01

    Houston-based Astro Technology Inc. used a partnership with Johnson Space Center to pioneer an advanced fiber-optic monitoring system for offshore oil pipelines. The company's underwater adhesives allow it to retrofit older deepwater systems in order to measure pressure, temperature, strain, and flow properties, giving energy companies crucial data in real time and significantly decreasing the risk of a catastrophe.

  9. Functional Electrical Stimulation Alters the Postural Component of Locomotor Activity in Healthy Humans

    PubMed Central

    Talis, Vera; Ballay, Yves; Grishin, Alexander; Pozzo, Thierry

    2015-01-01

    Knowledge of the effects of Functional Electrical Stimulation (FES) of different intensity on postural stability during walking in healthy subjects is necessary before these relationships in patients with postural disorders can be assessed and understood. We examined healthy subjects in Control group walking on a treadmill for 40 min and in FES group—provided with 30 min of stimulation, which intensity increased every 10 min. The main difference between Control and FES group was the progressive increase of trunk oscillations in sagittal, frontal, and horizontal planes and an increase of relative stance duration in parallel with FES intensity increase. Both Control and FES groups exhibited shank elevation angle increase as an after-effect. It is concluded, that high intensity FES significantly changes the postural component of locomotor activity, but the fatigue signs afterwards were not FES specific. PMID:26733791

  10. Sensory-evoked perturbations of locomotor activity by sparse sensory input: a computational study

    PubMed Central

    Brownstone, Robert M.

    2015-01-01

    Sensory inputs from muscle, cutaneous, and joint afferents project to the spinal cord, where they are able to affect ongoing locomotor activity. Activation of sensory input can initiate or prolong bouts of locomotor activity depending on the identity of the sensory afferent activated and the timing of the activation within the locomotor cycle. However, the mechanisms by which afferent activity modifies locomotor rhythm and the distribution of sensory afferents to the spinal locomotor networks have not been determined. Considering the many sources of sensory inputs to the spinal cord, determining this distribution would provide insights into how sensory inputs are integrated to adjust ongoing locomotor activity. We asked whether a sparsely distributed set of sensory inputs could modify ongoing locomotor activity. To address this question, several computational models of locomotor central pattern generators (CPGs) that were mechanistically diverse and generated locomotor-like rhythmic activity were developed. We show that sensory inputs restricted to a small subset of the network neurons can perturb locomotor activity in the same manner as seen experimentally. Furthermore, we show that an architecture with sparse sensory input improves the capacity to gate sensory information by selectively modulating sensory channels. These data demonstrate that sensory input to rhythm-generating networks need not be extensively distributed. PMID:25673740

  11. Hemodynamic Response of the Supplementary Motor Area during Locomotor Tasks with Upright versus Horizontal Postures in Humans

    PubMed Central

    Obayashi, Shigeru; Nakajima, Katsumi; Hara, Yukihiro

    2016-01-01

    To understand cortical mechanisms related to truncal posture control during human locomotion, we investigated hemodynamic responses in the supplementary motor area (SMA) with quadrupedal and bipedal gaits using functional near-infrared spectroscopy in 10 healthy adults. The subjects performed three locomotor tasks where the degree of postural instability varied biomechanically, namely, hand-knee quadrupedal crawling (HKQuad task), upright quadrupedalism using bilateral Lofstrand crutches (UpQuad task), and typical upright bipedalism (UpBi task), on a treadmill. We measured the concentration of oxygenated hemoglobin (oxy-Hb) during the tasks. The oxy-Hb significantly decreased in the SMA during the HKQuad task, whereas it increased during the UpQuad task. No significant responses were observed during the UpBi task. Based on the degree of oxy-Hb responses, we ranked these locomotor tasks as UpQuad > UpBi > HKQuad. The order of the different tasks did not correspond with postural instability of the tasks. However, qualitative inspection of oxy-Hb time courses showed that oxy-Hb waveform patterns differed between upright posture tasks (peak-plateau-trough pattern for the UpQuad and UpBi tasks) and horizontal posture task (downhill pattern for the HKQuad task). Thus, the SMA may contribute to the control of truncal posture accompanying locomotor movements in humans. PMID:27413555

  12. Nicotine-induced place conditioning and locomotor activity in an adolescent animal model of attention deficit/hyperactivity disorder (ADHD).

    PubMed

    Watterson, Elizabeth; Daniels, Carter W; Watterson, Lucas R; Mazur, Gabriel J; Brackney, Ryan J; Olive, M Foster; Sanabria, Federico

    2015-09-15

    Attention deficit/hyperactivity disorder (ADHD) is a risk factor for tobacco use and dependence. This study examines the responsiveness to nicotine of an adolescent model of ADHD, the spontaneously hypertensive rat (SHR). The conditioned place preference (CPP) procedure was used to assess nicotine-induced locomotion and conditioned reward in SHR and the Wistar Kyoto (WKY) control strain over a range of nicotine doses (0.0, 0.1, 0.3 and 0.6 mg/kg). Prior to conditioning, SHRs were more active and less biased toward one side of the CPP chamber than WKY rats. Following conditioning, SHRs developed CPP to the highest dose of nicotine (0.6 mg/kg), whereas WKYs did not develop CPP to any nicotine dose tested. During conditioning, SHRs displayed greater locomotor activity in the nicotine-paired compartment than in the saline-paired compartment across conditioning trials. SHRs that received nicotine (0.1, 0.3, 0.6 mg/kg) in the nicotine-paired compartment showed an increase in locomotor activity between conditioning trials. Nicotine did not significantly affect WKY locomotor activity. These findings suggest that the SHR strain is a suitable model for studying ADHD-related nicotine use and dependence, but highlights potential limitations of the WKY control strain and the CPP procedure for modeling ADHD-related nicotine reward.

  13. Chemokines and cocaine: CXCR4 receptor antagonist AMD3100 attenuates cocaine place preference and locomotor stimulation in rats.

    PubMed

    Kim, Jae; Connelly, Krista L; Unterwald, Ellen M; Rawls, Scott M

    2016-08-26

    Plasma levels of the chemokine CXCL12 are elevated in mice following acute cocaine exposure and decreased in human cocaine abusers during withdrawal. CXCL12 is also one of the few chemokines located in the brain and can modulate dopamine transmission through activation of its receptor CXCR4. To assess a role for the CXCL12/CXCR4 system in behavioral effects of cocaine, we tested the hypothesis that AMD 3100 (Plerixafor), a CXCR4 antagonist, would inhibit conditioned place preference (CPP) and locomotor activation produced by cocaine. Rats injected with cocaine (10mg/kg) displayed CPP relative to saline-injected controls following 4 conditioning sessions. AMD 3100 (1, 2.5, 5mg/kg) administered prior to cocaine conditioning reduced development of cocaine CPP. AMD 3100 (5mg/kg) also inhibited expression of cocaine-induced CPP in a paradigm in which it was injected once (following cocaine conditioning and just prior to CPP testing). In addition, AMD 3100 (5, 10mg/kg) pretreatment reduced locomotor activation produced by an acute cocaine injection (15mg/kg) but did not affect basal locomotor activity relative to saline-injected controls. Repeated cocaine exposure produced a significant increase (1.49-fold) in CXCL12 mRNA expression in the ventral tegmental area (VTA). Our results suggest that the CXCL12/CXCR4 system in the brain reward circuit is impacted by cocaine exposure and influences behavioral effects related to the abuse liability of cocaine.

  14. Chronic nicotine alters cannabinoid-mediated locomotor activity and receptor density in periadolescent but not adult male rats

    PubMed Central

    Werling, Linda L.; Reed, Stephanie Collins; Wade, Dean; Izenwasser, Sari

    2009-01-01

    A significant number of youths use cigarettes, and more than half of the youths who smoke daily also use illicit drugs. The focus of these studies is on how exposure to nicotine affects subsequent responses to both nicotine and cannabinoids in adolescents compared with adults. We have shown previously that chronic treatment with nicotine produces sensitization to its locomotor-activating effects in female and adult rats but not male adolescent rats. To better understand the effects of nicotine on adolescent and adult rats, rats were injected with nicotine or saline for 7 days and, on day 8, either challenged with delta-9-tetrahydrocannabinol (Δ9-THC) or the cannabinoid agonist CP 55,940 and tested for locomotor activity, or the brains were removed for quantitative autoradiography studies of the cannabinoid1 receptor. A separate group of rats was treated with nicotine plus the cannabinoid antagonist AM 251 and then challenged with CP 55,940. In adolescent male rats, nicotine administration led to sensitization to the locomotor-decreasing effects of both Δ9-THC and CP 55,940, but in adult male rats, the response to either drug was unchanged compared to controls. The effect of nicotine on CP 55,940-mediated locomotor activity was blocked by co-administration of AM 251 with the nicotine. Further, cannabinoid receptor density was increased in the prelimbic prefrontal cortex, ventral tegmental area, and select regions of the hippocampus in adolescent male rats pretreated with nicotine compared to vehicle-treated controls. There were no significant changes in cannabinoid receptor binding, however, in any of the brain regions examined in adult males pretreated with nicotine. The prelimbic prefrontal cortex and the hippocampus have been shown previously to be involved in stimulant reinforcement; thus it is possible that these changes contribute to the unique behavioral effects of chronic nicotine and subsequent drug administration in adolescents compared with adults. PMID

  15. Low doses of ivermectin cause sensory and locomotor disorders in dung beetles

    NASA Astrophysics Data System (ADS)

    Verdú, José R.; Cortez, Vieyle; Ortiz, Antonio J.; González-Rodríguez, Estela; Martinez-Pinna, Juan; Lumaret, Jean-Pierre; Lobo, Jorge M.; Numa, Catherine; Sánchez-Piñero, Francisco

    2015-09-01

    Ivermectin is a veterinary pharmaceutical generally used to control the ecto- and endoparasites of livestock, but its use has resulted in adverse effects on coprophilous insects, causing population decline and biodiversity loss. There is currently no information regarding the direct effects of ivermectin on dung beetle physiology and behaviour. Here, based on electroantennography and spontaneous muscle force tests, we show sub-lethal disorders caused by ivermectin in sensory and locomotor systems of Scarabaeus cicatricosus, a key dung beetle species in Mediterranean ecosystems. Our findings show that ivermectin decreases the olfactory and locomotor capacity of dung beetles, preventing them from performing basic biological activities. These effects are observed at concentrations lower than those usually measured in the dung of treated livestock. Taking into account that ivermectin acts on both glutamate-gated and GABA-gated chloride ion channels of nerve and muscle cells, we predict that ivermectin’s effects at the physiological level could influence many members of the dung pat community. The results indicate that the decline of dung beetle populations could be related to the harmful effects of chemical contamination in the dung.

  16. Chronic intermittent heroin produces locomotor sensitization and long-lasting enhancement of conditioned reinforcement.

    PubMed

    Morrison, J; Thornton, V; Ranaldi, R

    2011-09-01

    In a previous study we showed that chronic intermittent heroin in rats enhanced responding with conditioned reinforcement and reversal learning of a conditioned magazine approach task when tested three days after the heroin treatment. Whether or not this enhanced appetitive learning persists after a protracted withdrawal period remains unknown and constitutes the aim of the present study. Forty-eight male Long Evans rats were each exposed to positive pairings of a light stimulus and food for 4 consecutive daily sessions. Then, two groups of rats received saline and two groups received heroin (2 mg/kg) injections before placement in activity monitors for 9 consecutive daily sessions. This was followed by testing in operant conditioning chambers where one lever produced the light stimulus previously paired with food and another no stimulus. For one saline and one heroin group this testing occurred after 2 days of withdrawal while for the other saline and heroin groups it occurred after 30 days of withdrawal. The results indicate that animals treated with heroin displayed progressively and significantly greater locomotor activity across sessions while animals treated with saline displayed locomotor activity that remained low and stable across sessions. In addition, the heroin groups in each withdrawal condition displayed significantly enhanced responding with conditioned reinforcement compared to their respective saline control groups. These results demonstrate that chronic intermittent heroin enhances appetitive learning for natural reinforcers and motivational processes and that this effect persists even after 30-days of withdrawal.

  17. Effects of salvinorin A on locomotor sensitization to D2/D3 dopamine agonist quinpirole.

    PubMed

    Beerepoot, Pieter; Lam, Vincent; Luu, Alice; Tsoi, Bernice; Siebert, Daniel; Szechtman, Henry

    2008-12-03

    Locomotor sensitization induced by the dopamine agonist quinpirole can be potentiated by co-treatment with the synthetic kappa opioid agonist U69593. The identification of salvinorin A, an active component of the psychotropic sage Salvia divinorum, as a structurally different agonist of kappa-opioid receptors raised the question of whether this compound would similarly potentiate sensitization to quinpirole. Rats were co-treated with 0.5 mg/kg quinpirole and either salvinorin A (0.04, 0.4 or 2.0 mg/kg) or U69593 (0.3 mg/kg). Control groups were co-treated with vehicle and saline, vehicle and quinpirole (0.5 mg/kg), or saline and salvinorin A (0.4 mg/kg). Rats were injected biweekly for a total of 10 injections and locomotor activity measured after each treatment. Results showed that the highest dose of salvinorin A potentiated sensitization to quinpirole as did U69593, the middle salvinorin A dose had no effect on quinpirole sensitization, and the lowest dose of salvinorin A attenuated sensitization to quinpirole. These findings indicate that structural differences between salvinorin A and U69593 do not affect the potentiation of quinpirole sensitization. Moreover, the opposite effects of high and low salvinorin A doses suggest that salvinorin A can produce bidirectional modulation of sensitization to dopamine agonists.

  18. Low doses of ivermectin cause sensory and locomotor disorders in dung beetles.

    PubMed

    Verdú, José R; Cortez, Vieyle; Ortiz, Antonio J; González-Rodríguez, Estela; Martinez-Pinna, Juan; Lumaret, Jean-Pierre; Lobo, Jorge M; Numa, Catherine; Sánchez-Piñero, Francisco

    2015-09-09

    Ivermectin is a veterinary pharmaceutical generally used to control the ecto- and endoparasites of livestock, but its use has resulted in adverse effects on coprophilous insects, causing population decline and biodiversity loss. There is currently no information regarding the direct effects of ivermectin on dung beetle physiology and behaviour. Here, based on electroantennography and spontaneous muscle force tests, we show sub-lethal disorders caused by ivermectin in sensory and locomotor systems of Scarabaeus cicatricosus, a key dung beetle species in Mediterranean ecosystems. Our findings show that ivermectin decreases the olfactory and locomotor capacity of dung beetles, preventing them from performing basic biological activities. These effects are observed at concentrations lower than those usually measured in the dung of treated livestock. Taking into account that ivermectin acts on both glutamate-gated and GABA-gated chloride ion channels of nerve and muscle cells, we predict that ivermectin's effects at the physiological level could influence many members of the dung pat community. The results indicate that the decline of dung beetle populations could be related to the harmful effects of chemical contamination in the dung.

  19. Low doses of ivermectin cause sensory and locomotor disorders in dung beetles

    PubMed Central

    Verdú, José R.; Cortez, Vieyle; Ortiz, Antonio J.; González-Rodríguez, Estela; Martinez-Pinna, Juan; Lumaret, Jean-Pierre; Lobo, Jorge M.; Numa, Catherine; Sánchez-Piñero, Francisco

    2015-01-01

    Ivermectin is a veterinary pharmaceutical generally used to control the ecto- and endoparasites of livestock, but its use has resulted in adverse effects on coprophilous insects, causing population decline and biodiversity loss. There is currently no information regarding the direct effects of ivermectin on dung beetle physiology and behaviour. Here, based on electroantennography and spontaneous muscle force tests, we show sub-lethal disorders caused by ivermectin in sensory and locomotor systems of Scarabaeus cicatricosus, a key dung beetle species in Mediterranean ecosystems. Our findings show that ivermectin decreases the olfactory and locomotor capacity of dung beetles, preventing them from performing basic biological activities. These effects are observed at concentrations lower than those usually measured in the dung of treated livestock. Taking into account that ivermectin acts on both glutamate-gated and GABA-gated chloride ion channels of nerve and muscle cells, we predict that ivermectin’s effects at the physiological level could influence many members of the dung pat community. The results indicate that the decline of dung beetle populations could be related to the harmful effects of chemical contamination in the dung. PMID:26350768

  20. Age-related forgetting in locomotor adaptation.

    PubMed

    Malone, Laura A; Bastian, Amy J

    2016-02-01

    The healthy aging process affects the ability to learn and remember new facts and tasks. Prior work has shown that motor learning can be adversely affected by non-motor deficits, such as time. Here we investigated how age, and a dual task influence the learning and forgetting of a new walking pattern. We studied healthy younger (<30 yo) and older adults (>50 yo) as they alternated between 5-min bouts of split-belt treadmill walking and resting. Older subjects learned a new walking pattern at the same rate as younger subjects, but forgot some of the new pattern during the rest breaks. We tested if forgetting was due to reliance on a cognitive strategy that was not fully engaged after rest breaks. When older subjects performed a dual cognitive task to reduce strategic control of split-belt walking, their adaptation rate slowed, but they still forgot much of the new pattern during the rest breaks. Our results demonstrate that the healthy aging process is one component that weakens motor memories during rest breaks and that this phenomenon cannot be explained solely by reliance on a conscious strategy in older adults.

  1. Ecology and caudal skeletal morphology in birds: the convergent evolution of pygostyle shape in underwater foraging taxa.

    PubMed

    Felice, Ryan N; O'Connor, Patrick M

    2014-01-01

    Birds exhibit a specialized tail that serves as an integral part of the flight apparatus, supplementing the role of the wings in facilitating high performance aerial locomotion. The evolution of this function for the tail contributed to the diversification of birds by allowing them to utilize a wider range of flight behaviors and thus exploit a greater range of ecological niches. The shape of the wings and the tail feathers influence the aerodynamic properties of a bird. Accordingly, taxa that habitually utilize different flight behaviors are characterized by different flight apparatus morphologies. This study explores whether differences in flight behavior are also associated with variation in caudal vertebra and pygostyle morphology. Details of the tail skeleton were characterized in 51 Aequornithes and Charadriiformes species. Free caudal vertebral morphology was measured using linear metrics. Variation in pygostyle morphology was characterized using Elliptical Fourier Analysis, a geometric morphometric method for the analysis of outline shapes. Each taxon was categorized based on flight style (flap, flap-glide, dynamic soar, etc.) and foraging style (aerial, terrestrial, plunge dive, etc.). Phylogenetic MANOVAs and Flexible Discriminant Analyses were used to test whether caudal skeletal morphology can be used to predict flight behavior. Foraging style groups differ significantly in pygostyle shape, and pygostyle shape predicts foraging style with less than 4% misclassification error. Four distinct lineages of underwater foraging birds exhibit an elongate, straight pygostyle, whereas aerial and terrestrial birds are characterized by a short, dorsally deflected pygostyle. Convergent evolution of a common pygostyle phenotype in diving birds suggests that this morphology is related to the mechanical demands of using the tail as a rudder during underwater foraging. Thus, distinct locomotor behaviors influence not only feather attributes but also the underlying

  2. Ecology and Caudal Skeletal Morphology in Birds: The Convergent Evolution of Pygostyle Shape in Underwater Foraging Taxa

    PubMed Central

    Felice, Ryan N.; O’Connor, Patrick M.

    2014-01-01

    Birds exhibit a specialized tail that serves as an integral part of the flight apparatus, supplementing the role of the wings in facilitating high performance aerial locomotion. The evolution of this function for the tail contributed to the diversification of birds by allowing them to utilize a wider range of flight behaviors and thus exploit a greater range of ecological niches. The shape of the wings and the tail feathers influence the aerodynamic properties of a bird. Accordingly, taxa that habitually utilize different flight behaviors are characterized by different flight apparatus morphologies. This study explores whether differences in flight behavior are also associated with variation in caudal vertebra and pygostyle morphology. Details of the tail skeleton were characterized in 51 Aequornithes and Charadriiformes species. Free caudal vertebral morphology was measured using linear metrics. Variation in pygostyle morphology was characterized using Elliptical Fourier Analysis, a geometric morphometric method for the analysis of outline shapes. Each taxon was categorized based on flight style (flap, flap-glide, dynamic soar, etc.) and foraging style (aerial, terrestrial, plunge dive, etc.). Phylogenetic MANOVAs and Flexible Discriminant Analyses were used to test whether caudal skeletal morphology can be used to predict flight behavior. Foraging style groups differ significantly in pygostyle shape, and pygostyle shape predicts foraging style with less than 4% misclassification error. Four distinct lineages of underwater foraging birds exhibit an elongate, straight pygostyle, whereas aerial and terrestrial birds are characterized by a short, dorsally deflected pygostyle. Convergent evolution of a common pygostyle phenotype in diving birds suggests that this morphology is related to the mechanical demands of using the tail as a rudder during underwater foraging. Thus, distinct locomotor behaviors influence not only feather attributes but also the underlying

  3. Underwater Coatings Testing for INEEL Fuel Basin Applications

    SciTech Connect

    Julia L. Tripp

    2004-01-01

    The Idaho National Engineering and Environmental Laboratory (INEEL) is deactivating several fuel storage basins. Airborne contamination is a concern when the sides of the basins are exposed and allowed to dry during water removal. One way of controlling this airborne contamination is to fix the contamination in place while the pool walls are still submerged. There are many underwater coatings available on the market that are used in marine, naval and other applications. A series of tests were run to determine whether the candidate underwater fixatives are easily applied and adhere well to the substrates (pool wall materials) found in INEEL fuel pools. The four pools considered included (1) Test Area North (TAN-607) with epoxy painted concrete walls; (2) Idaho Nuclear Technology and Engineering Center (INTEC) (CPP-603) with bare concrete walls; (3) Materials Test Reactor (MTR) Canal with stainless steel lined concrete walls; and (4) Power Burst Facility (PBF-620) with stainless steel lined concrete walls on the bottom and epoxy painted carbon steel lined walls on the upper portions. Therefore, the four materials chosen for testing included bare concrete, epoxy painted concrete, epoxy painted carbon steel, and stainless steel. The typical water temperature of the pools varies from 55 F to 80 F dependent on the pool and the season. These tests were done at room temperature.

  4. Trajectory-Based Visual Localization in Underwater Surveying Missions

    PubMed Central

    Burguera, Antoni; Bonin-Font, Francisco; Oliver, Gabriel

    2015-01-01

    We present a new vision-based localization system applied to an autonomous underwater vehicle (AUV) with limited sensing and computation capabilities. The traditional EKF-SLAM approaches are usually expensive in terms of execution time; the approach presented in this paper strengthens this method by adopting a trajectory-based schema that reduces the computational requirements. The pose of the vehicle is estimated using an extended Kalman filter (EKF), which predicts the vehicle motion by means of a visual odometer and corrects these predictions using the data associations (loop closures) between the current frame and the previous ones. One of the most important steps in this procedure is the image registration method, as it reinforces the data association and, thus, makes it possible to close loops reliably. Since the use of standard EKFs entail linearization errors that can distort the vehicle pose estimations, the approach has also been tested using an iterated Kalman filter (IEKF). Experiments have been conducted using a real underwater vehicle in controlled scenarios and in shallow sea waters, showing an excellent performance with very small errors, both in the vehicle pose and in the overall trajectory estimates. PMID:25594602

  5. Individual differences in cocaine-induced locomotor activity of male Sprague-Dawley rats are not explained by plasma corticosterone levels.

    PubMed

    Nelson, Anna M; Kleschen, Melissa J; Zahniser, Nancy R

    2010-05-26

    Humans differ in their initial response to, and subsequent abuse of, addictive drugs like cocaine. Rodents also exhibit marked individual differences in responsiveness to cocaine. Previously, we classified male Sprague-Dawley rats as either low or high cocaine responders (LCRs or HCRs, respectively), based on their acute low-dose cocaine-induced locomotor activity, and found that with repeated drug exposure LCRs exhibit greater cocaine locomotor sensitization, reward and reinforcement than HCRs. Differential cocaine-induced increases in striatal dopamine help to explain the LCR/HCR phenotypes. Differential levels of stress and/or anxiety could also contribute but have not been explored. Here we measured open-field activity and plasma corticosterone levels both pre- and post-cocaine treatment in LCRs, HCRs, and saline-treated controls. The three groups did not differ in baseline locomotor activity or corticosterone levels. Importantly, LCR/HCR differences in corticosterone levels were also not observed following acute cocaine (10mg/kg, i.p.), when cocaine induced approximately 3.5-fold greater locomotor activity in HCRs than LCRs. Additionally, there were no LCR/HCR differences in plasma corticosterone levels following 5 days of once-daily cocaine, during which time LCRs developed locomotor sensitization such that their cocaine-induced locomotor activity no longer differed from that of HCRs. Likewise, there were no group activity differences in any of four concentric zones within the open-field chamber. In summary, neither plasma corticosterone levels nor thigmotaxis-type anxiety appears to be a factor that contributes to the observed cocaine-induced LCR/HCR behavioral differences.

  6. Astrocyte deletion of Bmal1 alters daily locomotor activity and cognitive functions via GABA signalling

    PubMed Central

    Barca-Mayo, Olga; Pons-Espinal, Meritxell; Follert, Philipp; Armirotti, Andrea; Berdondini, Luca; De Pietri Tonelli, Davide

    2017-01-01

    Circadian rhythms are controlled by a network of clock neurons in the central pacemaker, the suprachiasmatic nucleus (SCN). Core clock genes, such as Bmal1, are expressed in SCN neurons and in other brain cells, such as astrocytes. However, the role of astrocytic clock genes in controlling rhythmic behaviour is unknown. Here we show that ablation of Bmal1 in GLAST-positive astrocytes alters circadian locomotor behaviour and cognition in mice. Specifically, deletion of astrocytic Bmal1 has an impact on the neuronal clock through GABA signalling. Importantly, pharmacological modulation of GABAA-receptor signalling completely rescues the behavioural phenotypes. Our results reveal a crucial role of astrocytic Bmal1 for the coordination of neuronal clocks and propose a new cellular target, astrocytes, for neuropharmacology of transient or chronic perturbation of circadian rhythms, where alteration of astrocytic clock genes might contribute to the impairment of the neurobehavioural outputs such as cognition. PMID:28186121

  7. ScoreCentre: a computer program to assist with collection and calculation of BBB locomotor scale data.

    PubMed

    Evans, R M; Davies, M

    2010-12-15

    The Basso, Beattie and Bresnahan (BBB) Locomotor Rating Scale is a standardized assessment scale for use in experimental spinal cord injury (SCI) research. This paper describes a computer program, ScoreCentre, which aims to simplify the recording and handling of BBB locomotor scale data. The program assists with the recording of observational data from open-field testing and then automatically calculates BBB scores. Possible errors associated with data entry and manual calculation of scores are thus essentially eliminated. In addition, significant time is saved by the automated derivation of scores and subscores and elimination of the need to manually transfer data from paper records to a computer. ScoreCentre can also be used as a training aid, to help familiarize users with the BBB scale and to explore how changes in the observations impact on overall BBB score. ScoreCentre includes simple experiment management functions such as control of trial blinding, administration of drugs in a blinded fashion and longitudinal data analysis. ScoreCentre provides all the advantages of electronic records, such as ease of use, analysis and archiving, and allows the elimination of paper records if appropriate. When paper records are required, for example for archiving and auditing, they can be automatically produced by ScoreCentre. ScoreCentre will assist with both the learning and use of the BBB locomotor scale, thus facilitating the use of this standardized outcome measure in SCI research. ScoreCentre is available to download from www.rmeonline.net/scorecentre.

  8. Pain Induced during Both the Acquisition and Retention Phases of Locomotor Adaptation Does Not Interfere with Improvements in Motor Performance

    PubMed Central

    Bouffard, Jason; Bouyer, Laurent J.; Roy, Jean-Sébastien

    2016-01-01

    Cutaneous pain experienced during locomotor training was previously reported to interfere with retention assessed in pain-free conditions. To determine whether this interference reflects consolidation deficits or a difficulty to transfer motor skills acquired in the presence of pain to a pain-free context, this study evaluated the effect of pain induced during both the acquisition and retention phases of locomotor learning. Healthy participants performed a locomotor adaptation task (robotized orthosis perturbing ankle movements during swing) on two consecutive days. Capsaicin cream was applied around participants' ankle on both days for the Pain group, while the Control group was always pain-free. Changes in movement errors caused by the perturbation were measured to assess global motor performance; temporal distribution of errors and electromyographic activity were used to characterize motor strategies. Pain did not interfere with global performance during the acquisition or the retention phases but was associated with a shift in movement error center of gravity to later in the swing phase, suggesting a reduction in anticipatory strategy. Therefore, previously reported retention deficits could be explained by contextual changes between acquisition and retention tests. This difficulty in transferring skills from one context to another could be due to pain-related changes in motor strategy. PMID:28053789

  9. Actions of incretin metabolites on locomotor activity, cognitive function and in vivo hippocampal synaptic plasticity in high fat fed mice.

    PubMed

    Porter, David; Faivre, Emilie; Flatt, Peter R; Hölscher, Christian; Gault, Victor A

    2012-05-01

    The incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) improve markers of cognitive function in obesity-diabetes, however, both are rapidly degraded to their major metabolites, GLP-1(9-36)amide and GIP(3-42), respectively. Therefore, the present study investigated effects of GLP-1(9-36)amide and GIP(3-42) on locomotor activity, cognitive function and hippocampal synaptic plasticity in mice with diet-induced obesity and insulin resistance. High-fat fed Swiss TO mice treated with GLP-1(9-36)amide, GIP(3-42) or exendin(9-39)amide (twice-daily for 60 days) did not exhibit any changes in bodyweight, non-fasting plasma glucose and plasma insulin concentrations or glucose tolerance compared with high-fat saline controls. Similarly, locomotor and feeding activity, O(2) consumption, CO(2) production, respiratory exchange ratio and energy expenditure were not altered by chronic treatment with incretin metabolites. Administration of the truncated metabolites did not alter general behavior in an open field test or learning and memory ability as recorded during an object recognition test. High-fat mice exhibited a significant impairment in hippocampal long-term potentiation (LTP) which was not affected by treatment with incretin metabolites. These data indicate that incretin metabolites do not influence locomotor activity, cognitive function and hippocampal synaptic plasticity when administered at pharmacological doses to mice fed a high-fat diet.

  10. Augmentation of Voluntary Locomotor Activity by Transcutaneous Spinal Cord Stimulation in Motor-Incomplete Spinal Cord-Injured Individuals.

    PubMed

    Hofstoetter, Ursula S; Krenn, Matthias; Danner, Simon M; Hofer, Christian; Kern, Helmut; McKay, William B; Mayr, Winfried; Minassian, Karen

    2015-10-01

    The level of sustainable excitability within lumbar spinal cord circuitries is one of the factors determining the functional outcome of locomotor therapy after motor-incomplete spinal cord injury. Here, we present initial data using noninvasive transcutaneous lumbar spinal cord stimulation (tSCS) to modulate this central state of excitability during voluntary treadmill stepping in three motor-incomplete spinal cord-injured individuals. Stimulation was applied at 30 Hz with an intensity that generated tingling sensations in the lower limb dermatomes, yet without producing muscle reflex activity. This stimulation changed muscle activation, gait kinematics, and the amount of manual assistance required from the therapists to maintain stepping with some interindividual differences. The effect on motor outputs during treadmill-stepping was essentially augmentative and step-phase dependent despite the invariant tonic stimulation. The most consistent modification was found in the gait kinematics, with the hip flexion during swing increased by 11.3° ± 5.6° across all subjects. This preliminary work suggests that tSCS provides for a background increase in activation of the lumbar spinal locomotor circuitry that has partially lost its descending drive. Voluntary inputs and step-related feedback build upon the stimulation-induced increased state of excitability in the generation of locomotor activity. Thus, tSCS essentially works as an electrical neuroprosthesis augmenting remaining motor control.

  11. Effects of fentanyl administration on locomotor response in horses with the G57C μ-opioid receptor polymorphism.

    PubMed

    Wetmore, Lois A; Pascoe, Peter J; Shilo-Benjamini, Yael; Lindsey, Jane C

    2016-08-01

    OBJECTIVE To determine the locomotor response to the administration of fentanyl in horses with and without the G57C polymorphism of the μ-opioid receptor. ANIMALS 20 horses of various breeds and ages (10 horses heterozygous for the G57C polymorphism and 10 age-, breed-, and sex-matched horses that did not have the G57C polymorphism). PROCEDURES The number of steps each horse took was counted over consecutive 2-minute periods for 20 minutes to determine a baseline value. The horse then received a bolus of fentanyl (20 μg/kg, IV), and the number of steps was again counted during consecutive 2-minute periods for 60 minutes. The mean baseline value was subtracted from each 2-minute period after fentanyl administration; step counts with negative values were assigned a value of 0. Data were analyzed by use of a repeated-measures ANOVA. RESULTS Data for 19 of 20 horses (10 horses with the G57C polymorphism and 9 control horses without the G57C polymorphism) were included in the analysis. Horses with the G57C polymorphism had a significant increase in locomotor activity, compared with results for horses without the polymorphism. There was a significant group-by-time interaction. CONCLUSIONS AND CLINICAL RELEVANCE Horses heterozygous for the G57C polymorphism of the μ-opioid receptor had an increased locomotor response to fentanyl administration, compared with the response for horses without this polymorphism. The clinical impact of this finding should be investigated.

  12. High-Intensity Locomotor Exercise Increases Brain-Derived Neurotrophic Factor in Individuals with Incomplete Spinal Cord Injury.

    PubMed

    Leech, Kristan A; Hornby, T George

    2017-03-15

    High-intensity locomotor exercise is suggested to contribute to improved recovery of locomotor function after neurological injury. This may be secondary to exercise-intensity-dependent increases in neurotrophin expression demonstrated previously in control subjects. However, rigorous examination of intensity-dependent changes in neurotrophin levels is lacking in individuals with motor incomplete spinal cord injury (SCI). Therefore, the primary aim of this study was to evaluate the effect of locomotor exercise intensity on peripheral levels of brain-derived neurotrophic factor (BDNF) in individuals with incomplete SCI. We also explored the impact of the Val66Met single-nucleotide polymorphism (SNP) on the BDNF gene on intensity-dependent changes. Serum concentrations of BDNF and insulin-like growth factor-1 (IGF-1), as well as measures of cardiorespiratory dynamics, were evaluated across different levels of exercise intensity achieved during a graded-intensity, locomotor exercise paradigm in 11 individuals with incomplete SCI. Our results demonstrate a significant increase in serum BDNF at high, as compared to moderate, exercise intensities (p = 0.01) and 15 and 30 min post-exercise (p < 0.01 for both), with comparison to changes at low intensity approaching significance (p = 0.05). Serum IGF-1 demonstrated no intensity-dependent changes. Significant correlations were observed between changes in BDNF and specific indicators of exercise intensity (e.g., rating of perceived exertion; R = 0.43; p = 0.02). Additionally, the data suggest that Val66Met SNP carriers may not exhibit intensity-dependent changes in serum BDNF concentration. Given the known role of BDNF in experience-dependent neuroplasticity, these preliminary results suggest that exercise intensity modulates serum BDNF concentrations and may be an important parameter of physical rehabilitation interventions after neurological injury.

  13. The Effects of 4-Methylethcathinone on Conditioned Place Preference, Locomotor Sensitization, and Anxiety-Like Behavior: A Comparison with Methamphetamine

    PubMed Central

    Xu, Peng; Qiu, Yi; Zhang, Yizhi; Βai, Yanping; Xu, Pengfei; Liu, Yuan; Kim, Jee Hyun

    2016-01-01

    Background: 4-Methylethcathinone is a drug that belongs to the second generation of synthetic cathinones, and recently it has been ranked among the most popular “legal highs”. Although it has similar in vitro neurochemical actions to other drugs such as cocaine, the behavioral effects of 4-methylethcathinone remain to be determined. Methods: The addictive potential and locomotor potentiation by 4-methylethcathinone were investigated in rats using the conditioned place preference and sensitization paradigm. Methamphetamine was used as a positive control. Because synthetic cathinones can have psychological effects, we also examined anxiety-like behavior using the elevated plus maze. Results: A conditioning dose of 10mg/kg 4-methylethcathinone was able to induce conditioned place preference and reinstatement (following 2 weeks of withdrawal). Acute or repeated injections of 4-methylethcathinone at 3 or 10mg/kg failed to alter locomotor activity. At 30mg/kg, however, acute 4-methylethcathinone increased locomotor activity compared with saline, while chronic 4-methylethcathinone induced a delayed and attenuated sensitization compared with methamphetamine. Additionally, repeated daily injections of 4-methylethcathinone (30mg/kg) reduced, whereas methamphetamine increased time spent by rats in the open arm of an elevated plus maze compared with saline injections. Interestingly, a 2-week withdrawal period following chronic injections of 4-methylethcathinone or methamphetamine increased time spent in the open arm in all rats. Conclusions: The rewarding properties of 4-methylethcathinone were found to be dissociated from its effects on locomotor activity. Additionally, chronic 4-methylethcathinone use may trigger abnormal anxious behaviors. These behavioral effects caused by 4-methylethcathinone appear to last even after a withdrawal period. PMID:26612552

  14. A Systematic Review of Exercise Training To Promote Locomotor Recovery in Animal Models of Spinal Cord Injury

    PubMed Central

    Callister, Robert J.; Callister, Robin; Galea, Mary P.

    2012-01-01

    Abstract In the early 1980s experiments on spinalized cats showed that exercise training on the treadmill could enhance locomotor recovery after spinal cord injury (SCI). In this review, we summarize the evidence for the effectiveness of exercise training aimed at promoting locomotor recovery in animal models of SCI. We performed a systematic search of the literature using Medline, Web of Science, and Embase. Of the 362 studies screened, 41 were included. The adult female rat was the most widely used animal model. The majority of studies (73%) reported that exercise training had a positive effect on some aspect of locomotor recovery. Studies employing a complete SCI were less likely to have positive outcomes. For incomplete SCI models, contusion was the most frequently employed method of lesion induction, and the degree of recovery depended on injury severity. Positive outcomes were associated with training regimens that involved partial weight-bearing activity, commenced within a critical period of 1–2 weeks after SCI, and maintained training for at least 8 weeks. Considerable heterogeneity in training paradigms and methods used to assess or quantify recovery was observed. A 13-item checklist was developed and employed to assess the quality of reporting and study design; only 15% of the studies had high methodological quality. We recommend that future studies include control groups, randomize animals to groups, conduct blinded assessments, report the extent of the SCI lesion, and report sample size calculations. A small battery of objective assessment methods including assessment of over-ground stepping should also be developed and routinely employed. This would allow future meta-analyses of the effectiveness of exercise interventions on locomotor recovery. PMID:22401139

  15. Design and Analysis of Underwater Acoustic Networks with Reflected Links

    NASA Astrophysics Data System (ADS)

    Emokpae, Lloyd

    -of-sight (LOS) and NLOS links by utilizing directional antennas, which will boost the signal-to-noise ratio (SNR) at the receiver while promoting NLOS usage. In our model, we employ a directional underwater acoustic antenna composed of an array of hydrophones that can be summed up at various phases and amplitudes resulting in a beam-former. We have also adopted a practical multimodal directional transducer concept which generates both directional and omni-directional beam patterns by combining the fundamental vibration modes of a cylindrical acoustic radiator. This allows the transducer to be electrically controlled and steered by simply adjusting the electrical voltage weights. A prototype acoustic modem is then developed to utilize the multimodal directional transducer for both LOS and NLOS communication. The acoustic modem has also been used as a platform for empirically validating our SBR communication model in a tank and with empirical data. Networking protocols have been developed to exploit the SBR communication model. These protocols include node discovery and localization, directional medium access control (D-MAC) and geographical routing. In node discovery and localization, each node will utilize SBR-based range measurements to its neighbors to determine their relative position. The D-MAC protocol utilizes directional antennas to increase the network throughput due to the spatial efficiency of the antenna model. In the proposed reflection-enabled directional MAC protocol (RED-MAC), each source node will be able to determine if an obstacle is blocking the LOS link to the destination and switch to the best NLOS link by utilizing surface/bottom reflections. Finally, we have developed a geographical routing algorithm which aims to establish the best stable route from a source node to a destination node. The optimized route is selected to achieve maximum network throughput. Extensive analysis of the network throughput when utilizing directional antennas is also presented

  16. Accuracy Assessment of Underwater Photogrammetric Three Dimensional Modelling for Coral Reefs

    NASA Astrophysics Data System (ADS)

    Guo, T.; Capra, A.; Troyer, M.; Gruen, A.; Brooks, A. J.; Hench, J. L.; Schmitt, R. J.; Holbrook, S. J.; Dubbini, M.

    2016-06-01

    Recent advances in automation of photogrammetric 3D modelling software packages have stimulated interest in reconstructing highly accurate 3D object geometry in unconventional environments such as underwater utilizing simple and low-cost camera systems. The accuracy of underwater 3D modelling is affected by more parameters than in single media cases. This study is part of a larger project on 3D measurements of temporal change of coral cover in tropical waters. It compares the accuracies of 3D point clouds generated by using images acquired from a system camera mounted in an underwater housing and the popular GoPro cameras respectively. A precisely measured calibration frame was placed in the target scene in order to provide accurate control information and also quantify the errors of the modelling procedure. In addition, several objects (cinder blocks) with various shapes were arranged in the air and underwater and 3D point clouds were generated by automated image matching. These were further used to examine the relative accuracy of the point cloud generation by comparing the point clouds of the individual objects with the objects measured by the system camera in air (the best possible values). Given a working distance of about 1.5 m, the GoPro camera can achieve a relative accuracy of 1.3 mm in air and 2.0 mm in water. The system camera achieved an accuracy of 1.8 mm in water, which meets our requirements for coral measurement in this system.

  17. Monitoring Locomotor Load in Soccer: Is Metabolic Power, Powerful?

    PubMed

    Buchheit, M; Manouvrier, C; Cassirame, J; Morin, J-B

    2015-12-01

    The aim of the present study was to examine the validity and reliability of metabolic power (P) estimated from locomotor demands during soccer-specific drills. 14 highly-trained soccer players performed a soccer-specific circuit with the ball (3×1-min bouts, interspersed with 30-s passive recovery) on 2 different occasions. Locomotor activity was monitored with 4-Hz GPSs, while oxygen update (VO2) was collected with a portable gas analyzer. P was calculated using either net VO2 responses and traditional calorimetry principles (PVO2, W.kg(-1)) or locomotor demands (PGPS, W.kg(-1)). Distance covered into different speed, acceleration and P zones was recorded. While PGPS was 29±10% lower than PVO2 (d<- 3) during the exercise bouts, it was 85±7% lower (d<- 8) during recovery phases. The typical error between PGPS vs. PVO2 was moderate: 19.8%, 90% confidence limits: (18.4;21.6). The correlation between both estimates of P was small: 0.24 (0.14;0.33). Very large day-to-day variations were observed for acceleration, deceleration and > 20 W.kg(-1) distances (all CVs > 50%), while average Po2 and PGPS showed CVs < 10%. ICC ranged from very low- (acceleration and > 20 W.kg(-1) distances) to-very high (PVO2). PGPS largely underestimates the energy demands of soccer-specific drills, especially during the recovery phases. The poor reliability of PGPS >20 W.kg(-1) questions its value for monitoring purposes in soccer.

  18. Locomotor energetics and leg length in hominid bipedality.

    PubMed

    Kramer, P A; Eck, G G

    2000-05-01

    Because bipedality is the quintessential characteristic of Hominidae, researchers have compared ancient forms of bipedality with modern human gait since the first clear evidence of bipedal australopithecines was unearthed over 70 years ago. Several researchers have suggested that the australopithecine form of bipedality was transitional between the quadrupedality of the African apes and modern human bipedality and, consequently, inefficient. Other researchers have maintained that australopithecine bipedality was identical to that of Homo. But is it reasonable to require that all forms of hominid bipedality must be the same in order to be optimized? Most attempts to evaluate the locomotor effectiveness of the australopithecines have, unfortunately, assumed that the locomotor anatomy of modern humans is the exemplar of consummate bipedality. Modern human anatomy is, however, the product of selective pressures present in the particular milieu in which Homo arose and it is not necessarily the only, or even the most efficient, bipedal solution possible. In this report, we investigate the locomotion of Australopithecus afarensis, as represented by AL 288-1, using standard mechanical analyses. The osteological anatomy of AL 288-1 and movement profiles derived from modern humans are applied to a dynamic model of a biped, which predicts the mechanical power required by AL 288-1 to walk at various velocities. This same procedure is used with the anatomy of a composite modern woman and a comparison made. We find that AL 288-1 expends less energy than the composite woman when locomoting at walking speeds. This energetic advantage comes, however, at a price: the preferred transition speed (from a walk to a run) of AL 288-1 was lower than that of the composite woman. Consequently, the maximum daily range of AL 288-1 may well have been substantially smaller than that of modern people. The locomotor anatomy of A. afarensis may have been optimized for a particular ecological niche

  19. Demonstration of an Ultrasonic Method for 3-D Visualization of Shallow Buried Underwater Objects

    DTIC Science & Technology

    2011-07-01

    with the X-Y positioning system attached. It is composed of an X-Y gantry system operated by underwater servo motors controlled by the operator’s...user interface errors there are in the software. The test was setup by placing the system over a tank of water containing know objects (Figure 4). The...Requirements Evaluation of all the user interface controls and outputs 3.4.3 Success Criteria 100% error free, all identified bugs have been

  20. Modular functional organisation of the axial locomotor system in salamanders.

    PubMed

    Cabelguen, Jean-Marie; Charrier, Vanessa; Mathou, Alexia

    2014-02-01

    Most investigations on tetrapod locomotion have been concerned with limb movements. However, there is compelling evidence that the axial musculoskeletal system contributes to important functions during locomotion. Adult salamanders offer a remarkable opportunity to examine these functions because these amphibians use axial undulations to propel themselves in both aquatic and terrestrial environments. In this article, we review the currently available biological data on axial functions during various locomotor modes in salamanders. We also present data showing the modular organisation of the neural networks that generate axial synergies during locomotion. The functional implication of this modular organisation is discussed.

  1. Ocean Research Enabled by Underwater Gliders

    NASA Astrophysics Data System (ADS)

    Rudnick, Daniel L.

    2016-01-01

    Underwater gliders are autonomous underwater vehicles that profile vertically by changing their buoyancy and use wings to move horizontally. Gliders are useful for sustained observation at relatively fine horizontal scales, especially to connect the coastal and open ocean. In this review, research topics are grouped by time and length scales. Large-scale topics addressed include the eastern and western boundary currents and the regional effects of climate variability. The accessibility of horizontal length scales of order 1 km allows investigation of mesoscale and submesoscale features such as fronts and eddies. Because the submesoscales dominate vertical fluxes in the ocean, gliders have found application in studies of biogeochemical processes. At the finest scales, gliders have been used to measure internal waves and turbulent dissipation. The review summarizes gliders' achievements to date and assesses their future in ocean observation.

  2. Ocean Research Enabled by Underwater Gliders.

    PubMed

    Rudnick, Daniel L

    2016-01-01

    Underwater gliders are autonomous underwater vehicles that profile vertically by changing their buoyancy and use wings to move horizontally. Gliders are useful for sustained observation at relatively fine horizontal scales, especially to connect the coastal and open ocean. In this review, research topics are grouped by time and length scales. Large-scale topics addressed include the eastern and western boundary currents and the regional effects of climate variability. The accessibility of horizontal length scales of order 1 km allows investigation of mesoscale and submesoscale features such as fronts and eddies. Because the submesoscales dominate vertical fluxes in the ocean, gliders have found application in studies of biogeochemical processes. At the finest scales, gliders have been used to measure internal waves and turbulent dissipation. The review summarizes gliders' achievements to date and assesses their future in ocean observation.

  3. Underwater wet welding consumables for offshore applications

    SciTech Connect

    Sanchez-Osio, A.; Liu, S.; Olson, D.L.; Ibarra, S.

    1993-12-31

    The use of underwater wet welding for offshore repairs has been limited mainly because of porosity in the resulting welds. With appropriate consumable design, however, it is possible to enhance weld metal toughness through microstructural refinement and to reduce porosity. New titanium and boron based consumables have been developed with which high toughness acicular ferrite can be produced in underwater wet welds. Titanium, by means of oxide formation, promoted an increase in weld metal acicular ferrite, while boron additions decreased the amount of grain boundary ferrite, further improving the microstructure. Porosity reduction was possible through the addition of calcium carbonate at approximately 13 wt. % in the coating. However, weld metal decarburization also resulted with the addition.

  4. Detecting underwater improvised explosive threats (DUIET)

    NASA Astrophysics Data System (ADS)

    Feeley, Terry

    2010-04-01

    Improvised Explosive Devices (IEDs) have presented a major threat in the wars in Afghanistan and Iraq. These devices are powerful homemade land mines that can be small and easily hidden near roadsides. They are then remotely detonated when Coalition Forces pass by either singly or in convoys. Their rapid detection, classification and destruction is key to the safety of troops in the area. These land based bombs will have an analogue in the underwater theater especially in ports, lakes, rivers and streams. These devices may be used against Americans on American soil as an element of the global war on terrorism (GWOT) Rapid detection and classification of underwater improvised explosive devices (UIED) is critical to protecting innocent lives and maintaining the day to day flow of commerce. This paper will discuss a strategy and tool set to deal with this potential threat.

  5. Computer simulations of WIGWAM underwater experiment

    SciTech Connect

    Kamegai, Minao; White, J.W.

    1993-11-01

    We performed computer simulations of the WIGWAM underwater experiment with a 2-D hydro-code, CALE. First, we calculated the bubble pulse and the signal strength at the closest gauge in one-dimensional geometry. The calculation shows excellent agreement with the measured data. Next, we made two-dimensional simulations of WIGWAM applying the gravity over-pressure, and calculated the signals at three selected gauge locations where measurements were recorded. The computed peak pressures at those gauge locations come well within the 15% experimental error bars. The signal at the farthest gauge is of the order of 200 bars. This is significant, because at this pressure the CALE output can be linked to a hydro-acoustics computer program, NPE Code (Nonlinear Progressive Wave-equation Code), to analyze the long distance propagation of acoustical signals from the underwater explosions on a global scale.

  6. Underwater sensor networks: a new energy efficient and robust architecture.

    PubMed

    Climent, Salvador; Capella, Juan Vicente; Meratnia, Nirvana; Serrano, Juan José

    2012-01-01

    The specific characteristics of underwater environments introduce new challenges for networking protocols. In this paper, a specialized architecture for underwater sensor networks (UWSNs) is proposed and evaluated. Experiments are conducted in order to analyze the suitability of this protocol for the subaquatic transmission medium. Moreover, different scheduling techniques are applied to the architecture in order to study their performance. In addition, given the harsh conditions of the underwater medium, different retransmission methods are combined with the scheduling techniques. Finally, simulation results illustrate the performance achievements of the proposed protocol in end-to-end delay, packet delivery ratio and energy consumption, showing that this protocol can be very suitable for the underwater medium.

  7. Calibration Techniques for Accurate Measurements by Underwater Camera Systems

    PubMed Central

    Shortis, Mark

    2015-01-01

    Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems. PMID:26690172

  8. Calibration Techniques for Accurate Measurements by Underwater Camera Systems.

    PubMed

    Shortis, Mark

    2015-12-07

    Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems.

  9. Conditioned place preference and locomotor sensitization after repeated administration of cocaine or methamphetamine in rats treated with epidermal growth factor during the neonatal period.

    PubMed

    Mizuno, Makoto; Malta, Romulo S; Nagano, Tadasato; Nawa, Hiroyuki

    2004-10-01

    Epidermal growth factor (EGF) and its structurally related proteins are involved in the developmental regulation of various brain neurons, including midbrain dopaminergic neurons. We recently reported EGF and EGF-receptor abnormalities in both the brain tissues and blood of schizophrenic patients. Administration of EGF to neonatal rats transiently increases tyrosine hydroxylase expression and subsequently results in behavioral abnormalities in prepulse inhibition of acoustic startle, locomotor activity, and social interaction after development. The enhanced locomotor and stereotypic responses of the neonatally EGF-treated rats are considered to be an animal model for positive schizophrenia symptoms. In the present study, we investigated psychostimulant sensitivity of neonatally EGF-treated rats. At the adult stage, EGF-treated rats were challenged with cocaine (15 mg/kg) or methamphetamine (1 mg/kg), and conditioned place preference and locomotor activity were examined. The rats that received EGF during the neonatal period had significantly higher conditioned place preference for where cocaine or methamphetamine was administered than controls. The neonatal EGF treatment enhanced behavioral response to methamphetamine and behavioral sensitization to cocaine at the adult stage. Drug-naive controls gradually increased locomotor responses to cocaine during their daily injections, whereas EGF-treated rats exhibited a larger increase in cocaine responses. These results indicate that overactivation of the EGF receptors (ErbB1) during the neonatal period influences future sensitivity to psychostimulants. Our findings indicate a potential link between EGF-receptor activation and drug addiction.

  10. Engineering and Design: Underwater Blast Monitoring

    DTIC Science & Technology

    2007-11-02

    91 l. Tussing, Ronald B. 1982 (Jul). "Accuracy and Response of Tourmaline Gages for Measurement of Underwater Explosion Phenomena," NSWC TR-82-294...of a water shock pressure gage is not important. The tourmaline crystal pressure gage is the preferred transducer for measuring water shock pressure...1982). Tourmaline crystal is piezoelectric, which enables it to convert pressure (force per unit area) to electric energy. It should be noted, however

  11. Tethered Antennas for Unmanned Underwater Vehicles

    DTIC Science & Technology

    2009-04-27

    Concepts The first design (Figure 1) was based on the concept of an airfoil kite. The shape of the tow body was built around a NACA5515 hydrofoil to...Underwater Vehicles Brooke Ocean Technology (USA) Inc. 6 Figure 1: Hydrofoil Design The second design was based on that of a boat hull...communications. A sharp bow was utilized to cut through the water to reduce drag when on the surface. Like the hydrofoil design the top profile was

  12. Inspecting the inside of underwater hull

    NASA Astrophysics Data System (ADS)

    Valkovic, Vladivoj; Sudac, Davorin

    2009-05-01

    In order to demonstrate the possibility of identifying the material within ship's underwater hull, sunken ships and other objects on the sea floor tests with the 14 MeV sealed tube neutron generator incorporated inside a small submarine submerged in the test basin filled with sea water have been performed. Results obtained for inspection of diesel fuel and explosive presence behind single and double hull constructions are presented.

  13. Optical Magnetometry for Detecting Underwater Objects

    DTIC Science & Technology

    2015-09-21

    on the fact that polarized laser light, in the presence of the Earths magnetic field, will exhibit a polarization rotation when reflected off the...Effect (SMOKE) and the Faraday effect. In both mechanisms, the degree of polarization rotation is proportional to Earths local magnetic field. Variations...in the Earths magnetic field due to an underwater object will result in variations in the polarization rotation of the laser light reflected off the

  14. Acoustic-Sensing Underwater Tow Cable

    DTIC Science & Technology

    2013-09-30

    cable. The towed sensor system includes an array of hydrophones designed to sense a variety of underwater acoustic signals based on a particular...made from a flexible waterproof material such as polyurethane, nylon, or high-density polyethylene. The jacket 16 serves as the substrate for a...Encasing the regions 18, the conductors 20, as well as exposed portions of the jacket 16, is another waterproof jacket 22. The jacket 22 can be

  15. Ejectable underwater sound source recovery assembly

    NASA Technical Reports Server (NTRS)

    Irick, S. C. (Inventor)

    1974-01-01

    An underwater sound source is described that may be ejectably mounted on any mobile device that travels over water, to facilitate in the location and recovery of the device when submerged. A length of flexible line maintains a connection between the mobile device and the sound source. During recovery, the sound source is located be particularly useful in the recovery of spent rocket motors that bury in the ocean floor upon impact.

  16. Underwater bipedal locomotion by octopuses in disguise.

    PubMed

    Huffard, Christine L; Boneka, Farnis; Full, Robert J

    2005-03-25

    Here we report bipedal movement with a hydrostatic skeleton. Two species of octopus walk on two alternating arms using a rolling gait and appear to use the remaining six arms for camouflage. Octopus marginatus resembles a coconut, and Octopus (Abdopus) aculeatus, a clump of floating algae. Using underwater video, we analyzed the kinematics of their strides. Each arm was on the sand for more than half of the stride, qualifying this behavior as a form of walking.

  17. Software-Defined Underwater Acoustic Networking Platform

    DTIC Science & Technology

    2009-11-03

    and USRP Software defined radio has received a lot of attention most notably in the research community. The ability to use soft- ware to modulate and...growth in the community. Our platform adapts some of these tools to work well with the underwater envi- ronment while maintaining flexibility...network stack. We adapted these widely sup- ported tools that have proven effective prototyping, devel- opment, and implementation for terrestrial

  18. Underwater Nondestructive Testing of Ship Hull Welds

    DTIC Science & Technology

    1979-09-01

    5. cowt * "n’d Mar(itini A~niamiitrati~on W.. P. N. UZD, Wr. P., a. XWLRA Dxr~etor Chiorf Brwmoh of M2rine 011 Butt iht~itwgL Dip"Jon and Gas ...Radiography, ultrasonic inspection, and magnetic particle testing are discussed including the modifications necessary for underwater applications . In... Measuring Weld Reinforcement 7 3 Recommended Positioning of Electrical Prods When Inspecting Butt Welds 7 4 An Example of Crack Detection Using

  19. Frequency Spreading in Underwater Acoustic Signal Transmission.

    DTIC Science & Technology

    1980-04-15

    acoustic signal transmitted and received underwater J-2 J.2 Signal spectrum computing block diagram. J-3 Chapter I. Frequency spreading 1.0 Introduction... transmitted frequency can be expected in the received signal [1] - [18]. This frequency spreading behavior is the result of the amplitude and phase...result of phase modulation of the transmitted sinusoid by the moving surface, and the separation between the spectral lines at the receiving point is

  20. Development of a Broadband Underwater Sound Projector

    DTIC Science & Technology

    1997-01-01

    classification systems use existing transducer designs, such as the tonpilz (piston) transducers . This type of design has been selected to provide a maximum...source level at 20 kHz with high efficiency and reliability as well as excellent directivity responses. The manufacturing of the tonpilz transducer is...an autonomous underwater vehicle (AUV). The transducer is resonant at 100 kHz but has been designed to deliver high sound pressure levels without

  1. UNDERWATER OBSERVATION OF SUBLITTORAL OF THE BARENTS SEA (Podvodnye Nablyudeniya v Sublitorali Barentseva Morya),

    DTIC Science & Technology

    MARINE BIOLOGY, ARCTIC OCEAN), (*DIVING, *ARCTIC REGIONS), UNDERWATER PHOTOGRAPHY, AQUATIC ANIMALS, ECOLOGY, DISTRIBUTION, UNDERWATER CAMERAS, VISIBILITY, OCEAN CURRENTS, SPONGES, ECHINODERMATA , USSR

  2. Adult Female Rats Altered Diurnal Locomotor Activity Pattern Following Chronic Methylphenidate Treatment

    PubMed Central

    Trinh, T.; Kohllepin, S; Yang, P.B.; Burau, K.D.; Dafny, N.

    2014-01-01

    Methylphenidate (MPD) is one of the most prescribed pharmacological agents and also used as cognitive enhancement and for recreational purposes. The objective of this study was to investigate the repetitive dose-response effects of MPD on rhythm locomotor activity pattern of female WKY rats and compare to prior study done on male. The hypothesis is that change in the circadian activity pattern indicates a long-lasting effect of the drug. Four animal groups (saline control, 0.6, 2.5, and 10.0 mg/kg MPD dose groups) were housed in a sound-controlled room at 12:12 light/dark cycle. All received saline injections on experimental day 1 (ED 1). On EDs 2-7, the control group received saline injection; the other groups received 0.6, 2.5, or 10.0 mg/kg MPD, respectively. On ED 8-10, injections were withheld. On ED 11, each group received the same dose as EDs 2-7. Hourly histograms and cosine statistical analyses calculating the acrophase (ϕ), amplitude (A), and MESOR (M) were applied to assess the 24-hour circadian activity pattern. The 0.6 and 2.5 mg/kg MPD groups exhibited significant (p<0.05) change in their circadian activity pattern on ED 11. The 10.0 mg/kg MPD group exhibited tolerance on ED 11 and also a significant change in activity pattern on ED 8 compared to ED 1, consistent with withdrawal behavior (p<0.007). In conclusion, chronic MPD administration alters circadian locomotor activity of adult female WKY rats and confirms that chronic MPD use elicits long lasting effects PMID:23893293

  3. Training Enhances Both Locomotor and Cognitive Adaptability to a Novel Sensory Environment

    NASA Technical Reports Server (NTRS)

    Bloomberg, J. J.; Peters, B. T.; Mulavara, A. P.; Brady, R. A.; Batson, C. D.; Ploutz-Snyder, R. J.; Cohen, H. S.

    2010-01-01

    During adaptation to novel gravitational environments, sensorimotor disturbances have the potential to disrupt the ability of astronauts to perform required mission tasks. The goal of this project is to develop a sensorimotor adaptability (SA) training program to facilitate rapid adaptation. We have developed a unique training system comprised of a treadmill placed on a motion-base facing a virtual visual scene that provides an unstable walking surface combined with incongruent visual flow designed to enhance sensorimotor adaptability. The goal of our present study was to determine if SA training improved both the locomotor and cognitive responses to a novel sensory environment and to quantify the extent to which training would be retained. Methods: Twenty subjects (10 training, 10 control) completed three, 30-minute training sessions during which they walked on the treadmill while receiving discordant support surface and visual input. Control subjects walked on the treadmill but did not receive any support surface or visual alterations. To determine the efficacy of training all subjects performed the Transfer Test upon completion of training. For this test, subjects were exposed to novel visual flow and support surface movement, not previously experienced during training. The Transfer Test was performed 20 minutes, 1 week, 1, 3 and 6 months after the final training session. Stride frequency, auditory reaction time, and heart rate data were collected as measures of postural stability, cognitive effort and anxiety, respectively. Results: Using mixed effects regression methods we determined that subjects who received SA training showed less alterations in stride frequency, auditory reaction time and heart rate compared to controls. Conclusion: Subjects who received SA training improved performance across a number of modalities including enhanced locomotor function, increased multi-tasking capability and reduced anxiety during adaptation to novel discordant sensory

  4. Apparatus for use in placing a submarine structure on the sea bed alongside an underwater well and method of drilling a plurality of closely spaced underwater wells

    SciTech Connect

    Shotbolt, K.

    1982-03-02

    A template for spacing a submarine structure such as an anchor block or a guide base for a second underwater well alongside an existing underwater well comprises a beam attached at one end, by means of a hinge, to a lowering guide which can be threaded over and be lowered along two guide wires of the first well, and at the other end by a remote-controlled release mechanism to the submarine structure such as the anchor block itself or a guide base for a second well. The beam, with such a submarine structure attached, is lowered down the guide wires while held in a vertical configuration, and is then swung into a generally horizontal configuration at the sea bed.

  5. Investigation of underwater welding of steel

    SciTech Connect

    Shannon, G.J.; Watson, J.; Deans, W.F. . Dept. of Engineering)

    1994-12-01

    The preliminary underwater welding study described forms part of a European funded research program (EUREKA EU194) which involves a feasibility study into laser welding applications in the offshore oil industry. An investigation was undertaken using a 1.2 KW carbon dioxide laser for underwater butt welding of BS 4360 43A and 50D steel, in order to assess the quality of the welds and to achieve an understanding of the laser/water/material interaction. Using a high-speed camera, the temporal behavior of the melt pool and ''plasma'' dynamics surrounded by an aqueous environment were monitored. Experiments were undertaken to characterize the attenuation of the laser beam in the water as a function of various focal length optics and depth of water. The effect of energy input conditions on the weld bead appearance and mechanical properties were also examined. The interaction of the laser beam with water produced a wave-guiding mechanism in which the focused beam instantaneously vaporizes the water and directs the beam on to the workpiece. The underwater weld beads exhibited sound microstructures over a range of weld energy inputs, mainly due to the formation of a ''dry region'' during welding. Metallurgical analysis of the welds showed a slight increase in hardness, though other post-weld mechanical strengths were similar to in-air results.

  6. Afocal viewport optics for underwater imaging

    NASA Astrophysics Data System (ADS)

    Slater, Dan

    2014-09-01

    A conventional camera can be adapted for underwater use by enclosing it in a sealed waterproof pressure housing with a viewport. The viewport, as an optical interface between water and air needs to consider both the camera and water optical characteristics while also providing a high pressure water seal. Limited hydrospace visibility drives a need for wide angle viewports. Practical optical interfaces between seawater and air vary from simple flat plate windows to complex water contact lenses. This paper first provides a brief overview of the physical and optical properties of the ocean environment along with suitable optical materials. This is followed by a discussion of the characteristics of various afocal underwater viewport types including flat windows, domes and the Ivanoff corrector lens, a derivative of a Galilean wide angle camera adapter. Several new and interesting optical designs derived from the Ivanoff corrector lens are presented including a pair of very compact afocal viewport lenses that are compatible with both in water and in air environments and an afocal underwater hyper-hemispherical fisheye lens.

  7. Exploring the role of locomotor sensitization in the circadian food entrainment pathway

    PubMed Central

    Opiol, Hanna; de Zavalia, Nuria; Delorme, Tara; Solis, Pavel; Rutherford, Spencer; Shalev, Uri; Amir, Shimon

    2017-01-01

    Food entrainment is the internal mechanism whereby the phase and period of circadian clock genes comes under the control of daily scheduled food availability. Food entrainment allows the body to efficiently realign the internal timing of behavioral and physiological functions such that they anticipate food intake. Food entrainment can occur with or without caloric restriction, as seen with daily schedules of restricted feeding (RF) or restricted treat (RT) that restrict food or treat intake to a single feeding time. However, the extent of clock gene control is more pronounced with caloric restriction, highlighting the role of energy balance in regulating clock genes. Recent studies have implicated dopamine (DA) to be involved in food entrainment and caloric restriction is known to affect dopaminergic pathways to enhance locomotor activity. Since food entrainment results in the development of a distinct behavioral component, called food anticipatory activity (FAA), we examined the role of locomotor sensitization (LS) in food entrainment by 1) observing whether amphetamine (AMPH) sensitization results in enhanced locomotor output of FAA and 2) measuring LS of circadian and non-circadian feeding paradigms to an acute injection of AMPH (AMPH cross-sensitization). Unexpectedly, AMPH sensitization did not show enhancement of FAA. On the contrary, LS did develop with sufficient exposure to RF. LS was present after 2 weeks of RF, but not after 1, 3 or 7 days into RF. When food was returned and rats regain their original body weight at 10–15 days post-RF, LS remained present. LS did not develop to RT, nor to feedings of a non-circadian schedule, e.g. variable restricted feeding (VRF) or variable RT (VRT). Further, when RF was timed to the dark period, LS was observed only when tested at night; RF timed to the light period resulted in LS that was present during day and night. Taken together our results show that LS develops with food entrainment to RF, an effect that is

  8. Locomotor stimulant and discriminative stimulus effects of 'bath salt' cathinones.

    PubMed

    Gatch, Michael B; Taylor, Cynthia M; Forster, Michael J

    2013-09-01

    A number of psychostimulant-like cathinone compounds are being sold as 'legal' alternatives to methamphetamine or cocaine. The purpose of these experiments was to determine whether cathinone compounds stimulate motor activity and have discriminative stimulus effects similar to those of cocaine and/or methamphetamine. 3,4-Methylenedioxypyrovalerone (MDPV), methylone, mephedrone, naphyrone, flephedrone, and butylone were tested for locomotor stimulant effects in mice and subsequently for substitution in rats trained to discriminate cocaine (10 mg/kg, intraperitoneally) or methamphetamine (1 mg/kg, intraperitoneally) from saline. All compounds fully substituted for the discriminative stimulus effects of cocaine and methamphetamine. Several commonly marketed cathinones produce discriminative stimulus effects comparable with those of cocaine and methamphetamine, which suggests that these compounds are likely to have similar abuse liabilities. MDPV and naphyrone produced locomotor stimulant effects that lasted much longer than those of cocaine or methamphetamine and therefore may be of particular concern, particularly because MDPV is one of the most commonly found substances associated with emergency room visits because of adverse effects of taking 'bath salts'.

  9. Dual dimensional nanostructures with highly durable non-wetting properties under dynamic and underwater conditions.

    PubMed

    Baek, Seunghyeon; Kim, Wuseok; Jeon, Sangmin; Yong, Kijung

    2017-03-23

    Non-wetting states with high durability under both dynamic and underwater conditions are very desirable for practical applications of superhydrophobic surfaces in various fields. Despite increasing demands for this dual stability of non-wetting surfaces, studies investigating both the impact dynamics and underwater stability are very rare. In the current study, we performed water droplet impact dynamics and underwater stability studies using ZnO/Si hierarchical nanostructures (HNs) as a model system. The effects of the surface structure on the non-wetting states under dynamic conditions were first studied by comparing various surface structures, such as ZnO nanowires (NWs), Si microposts (MPs), ZnO/Si HNs with controlled MP interspacings, and lotus leaf (LL). The growth of ZnO NWs on Si MPs drastically improves the non-wetting properties of Si MPs under dynamic conditions. The transition of wetting states from the Cassie-Baxter state to the Wenzel state occurs on ZnO/Si HNs as the impact velocity increases. Measurement of the critical We number during transition enables us to determine the important parameters of wetting pressure using a simple model. Moreover, compared to Si MPs, ZnO NWs, and LL, our ZnO/Si HNs exhibit dramatically increased air pocket lifetimes under underwater conditions, which is due to the enhanced capillary pressure originating from the dual dimensional hierarchical structure. Our study indicates that optimally designed hierarchical surfaces have remarkably high durability non-wetting states under both dynamic and underwater conditions, expanding the potential application of non-wetting surfaces.

  10. Scaling Behavior of Human Locomotor Activity Amplitude: Association with Bipolar Disorder

    PubMed Central

    Indic, Premananda; Salvatore, Paola; Maggini, Carlo; Ghidini, Stefano; Ferraro, Gabriella; Baldessarini, Ross J.; Murray, Greg

    2011-01-01

    Scale invariance is a feature of complex biological systems, and abnormality of multi-scale behaviour may serve as an indicator of pathology. The hypothalamic suprachiasmatic nucleus (SCN) is a major node in central neural networks responsible for regulating multi-scale behaviour in measures of human locomotor activity. SCN also is implicated in the pathophysiology of bipolar disorder (BD) or manic-depressive illness, a severe, episodic disorder of mood, cognition and behaviour. Here, we investigated scaling behaviour in actigraphically recorded human motility data for potential indicators of BD, particularly its manic phase. A proposed index of scaling behaviour (Vulnerability Index [VI]) derived from such data distinguished between: [i] healthy subjects at high versus low risk of mood disorders; [ii] currently clinically stable BD patients versus matched controls; and [iii] among clinical states in BD patients. PMID:21655197

  11. A single dopamine pathway underlies progressive locomotor deficits in a Drosophila model of Parkinson disease.

    PubMed

    Riemensperger, Thomas; Issa, Abdul-Raouf; Pech, Ulrike; Coulom, Hélène; Nguyễn, Mỹ-Vân; Cassar, Marlène; Jacquet, Mélanie; Fiala, André; Birman, Serge

    2013-11-27

    Expression of the human Parkinson-disease-associated protein α-synuclein in all Drosophila neurons induces progressive locomotor deficits. Here, we identify a group of 15 dopaminergic neurons per hemisphere in the anterior medial region of the brain whose disruption correlates with climbing impairments in this model. These neurons selectively innervate the horizontal β and β' lobes of the mushroom bodies, and their connections to the Kenyon cells are markedly reduced when they express α-synuclein. Using selective mushroom body drivers, we show that blocking or overstimulating neuronal activity in the β' lobe, but not the β or γ lobes, significantly inhibits negative geotaxis behavior. This suggests that modulation of the mushroom body β' lobes by this dopaminergic pathway is specifically required for an efficient control of startle-induced locomotion in flies.

  12. Dopamine-independent locomotor actions of amphetamines in a novel acute mouse model of Parkinson disease.

    PubMed

    Sotnikova, Tatyana D; Beaulieu, Jean-Martin; Barak, Larry S; Wetsel, William C; Caron, Marc G; Gainetdinov, Raul R

    2005-08-01

    Brain dopamine is critically involved in movement control, and its deficiency is the primary cause of motor symptoms in Parkinson disease. Here we report development of an animal model of acute severe dopamine deficiency by using mice lacking the dopamine transporter. In the absence of transporter-mediated recycling mechanisms, dopamine levels become entirely dependent on de novo synthesis. Acute pharmacological inhibition of dopamine synthesis in these mice induces transient elimination of striatal dopamine accompanied by the development of a striking behavioral phenotype manifested as severe akinesia, rigidity, tremor, and ptosis. This phenotype can be reversed by administration of the dopamine precursor, L-DOPA, or by nonselective dopamine agonists. Surprisingly, several amphetamine derivatives were also effective in reversing these behavioral abnormalities in a dopamine-independent manner. Identification of dopamine transporter- and dopamine-independent locomotor actions of amphetamines suggests a novel paradigm in the search for prospective anti-Parkinsonian drugs.

  13. Firing Dynamics and Modulatory Actions of Supraspinal Dopaminergic Neurons during Zebrafish Locomotor Behavior

    PubMed Central

    Jay, Michael; De Faveri, Francesca; McDearmid, Jonathan Robert

    2015-01-01

    Summary Background Dopamine (DA) has long been known to have modulatory effects on vertebrate motor circuits. However, the types of information encoded by supraspinal DAergic neurons and their relationship to motor behavior remain unknown. Results By conducting electrophysiological recordings from awake, paralyzed zebrafish larvae that can produce behaviorally relevant activity patterns, we show that supraspinal DAergic neurons generate two forms of output: tonic spiking and phasic bursting. Using paired supraspinal DA neuron and motoneuron recordings, we further show that these firing modes are associated with specific behavioral states. Tonic spiking is prevalent during periods of inactivity while bursting strongly correlates with locomotor output. Targeted laser ablation of supraspinal DA neurons reduces motor episode frequency without affecting basic parameters of motor output, strongly suggesting that these cells regulate spinal network excitability. Conclusions Our findings reveal how vertebrate motor circuit flexibility is temporally controlled by supraspinal DAergic pathways and provide important insights into the functional significance of this evolutionarily conserved cell population. PMID:25639243

  14. Effects of reduced plantar cutaneous afferent feedback on locomotor adjustments in dynamic stability during perturbed walking.

    PubMed

    Höhne, Angela; Stark, Christian; Brüggemann, Gert-Peter; Arampatzis, Adamantios

    2011-08-11

    This study examined the effects of reduced plantar cutaneous afferent feedback on predictive and feedback adaptive locomotor adjustments in dynamic stability during perturbed walking. Twenty-two matched participants divided between an experimental-group and a control-group performed a gait protocol, which included surface alterations to one covered exchangeable gangway-element (hard/soft). In the experimental-group, cutaneous sensation in both foot soles was reduced to the level of sensory peripheral neuropathy by means of intradermal injections of an anaesthetic solution, without affecting foot proprioception or muscles. The gait protocol consisted of baseline trials on a uniformly hard surface and an adaptation phase consisting of nineteen trials incorporating a soft gangway-element, interspersed with three trials using the hard surface-element (2nd, 8th and 19th). Dynamic stability was assessed by quantifying the margin of stability (MS), which was calculated as the difference between the base of support (BS) and the extrapolated centre of mass (CM). The horizontal velocity of the CM and its vertical projection in the anterior-posterior direction and the eigenfrequency of an inverted pendulum determine the extrapolated-CM. Both groups increased the BS at the recovery step in response to the first unexpected perturbation. These feedback corrections were used more extensively in the experimental-group, which led to a higher MS compared to the control-group, i.e. a more stable body-position. In the adaptation phase the MS returned to baseline similarly in both groups. In the trial on the hard surface directly after the first perturbation, both groups increased the MS at touchdown of the disturbed leg compared to baseline trials, indicating rapid predictive adjustments irrespective of plantar cutaneous input. Our findings demonstrate that the locomotor adaptational potential does not decrease due to the loss of plantar sensation.

  15. Decomposition of abnormal free locomotor behavior in a rat model of Parkinson's disease

    PubMed Central

    Grieb, Benjamin; von Nicolai, Constantin; Engler, Gerhard; Sharott, Andrew; Papageorgiou, Ismini; Hamel, Wolfgang; Engel, Andreas K.; Moll, Christian K.

    2013-01-01

    Poverty of spontaneous movement, slowed execution and reduced amplitudes of movement (akinesia, brady- and hypokinesia) are cardinal motor manifestations of Parkinson's disease that can be modeled in experimental animals by brain lesions affecting midbrain dopaminergic neurons. Most behavioral investigations in experimental parkinsonism have employed short-term observation windows to assess motor impairments. We postulated that an analysis of longer-term free exploratory behavior could provide further insights into the complex fine structure of altered locomotor activity in parkinsonian animals. To this end, we video-monitored 23 h of free locomotor behavior and extracted several behavioral measures before and after the expression of a severe parkinsonian phenotype following bilateral 6-hydroxydopamine (6-OHDA) lesions of the rat dopaminergic substantia nigra. Unbiased stereological cell counting verified the degree of midbrain tyrosine hydroxylase positive cell loss in the substantia nigra and ventral tegmental area. In line with previous reports, overall covered distance and maximal motion speed of lesioned animals were found to be significantly reduced compared to controls. Before lesion surgery, exploratory rat behavior exhibited a bimodal distribution of maximal speed values obtained for single movement episodes, corresponding to a “first” and “second gear” of motion. 6-OHDA injections significantly reduced the incidence of second gear motion episodes and also resulted in an abnormal prolongation of these fast motion events. Likewise, the spatial spread of such episodes was increased in 6-OHDA rats. The increase in curvature of motion tracks was increased in both lesioned and control animals. We conclude that the discrimination of distinct modes of motion by statistical decomposition of longer-term spontaneous locomotion provides useful insights into the fine structure of fluctuating motor functions in a rat analog of Parkinson's disease. PMID:24348346

  16. Locomotor Tests Predict Community Mobility in Children and Youth with Cerebral Palsy

    ERIC Educational Resources Information Center

    Ferland, Chantale; Moffet, Helene; Maltais, Desiree

    2012-01-01

    Ambulatory children and youth with cerebral palsy have limitations in locomotor capacities and in community mobility. The ability of three locomotor tests to predict community mobility in this population (N = 49, 27 boys, 6-16 years old) was examined. The tests were a level ground walking test, the 6-min-Walk-Test (6MWT), and two tests of advanced…

  17. White - cGMP Interaction Promotes Fast Locomotor Recovery from Anoxia in Adult Drosophila

    PubMed Central

    2017-01-01

    Increasing evidence indicates that the white (w) gene in Drosophila possesses extra-retinal functions in addition to its classical role in eye pigmentation. We have previously shown that w+ promotes fast and consistent locomotor recovery from anoxia, but how w+ modulates locomotor recovery is largely unknown. Here we show that in the absence of w+, several PDE mutants, especially cyclic guanosine monophosphate (cGMP)-specific PDE mutants, display wildtype-like fast locomotor recovery from anoxia, and that during the night time, locomotor recovery was light-sensitive in white-eyed mutant w1118, and light-insensitive in PDE mutants under w1118 background. Data indicate the involvement of cGMP in the modulation of recovery timing and presumably, light-evoked cGMP fluctuation is associated with light sensitivity of locomotor recovery. This was further supported by the observations that w-RNAi-induced delay of locomotor recovery was completely eliminated by upregulation of cGMP through multiple approaches, including PDE mutation, simultaneous overexpression of an atypical soluble guanylyl cyclase Gyc88E, or sildenafil feeding. Lastly, prolonged sildenafil feeding promoted fast locomotor recovery from anoxia in w1118. Taken together, these data suggest that a White-cGMP interaction modulates the timing of locomotor recovery from anoxia. PMID:28060942

  18. Treadmill training promotes spinal changes leading to locomotor recovery after partial spinal cord injury in cats.

    PubMed

    Martinez, Marina; Delivet-Mongrain, Hugo; Rossignol, Serge

    2013-06-01

    After a spinal hemisection at thoracic level in cats, the paretic hindlimb progressively recovers locomotion without treadmill training but asymmetries between hindlimbs persist for several weeks and can be seen even after a further complete spinal transection at T13. To promote optimal locomotor recovery after hemisection, such asymmetrical changes need to be corrected. In the present study we determined if the locomotor deficits induced by a spinal hemisection can be corrected by locomotor training and, if so, whether the spinal stepping after the complete spinal cord transection is also more symmetrical. This would indicate that locomotor training in the hemisected period induces efficient changes in the spinal cord itself. Sixteen adult cats were first submitted to a spinal hemisection at T10. One group received 3 wk of treadmill training, whereas the second group did not. Detailed kinematic and electromyographic analyses showed that a 3-wk period of locomotor training was sufficient to improve the quality and symmetry of walking of the hindlimbs. Moreover, after the complete spinal lesion was performed, all the trained cats reexpressed bilateral and symmetrical hindlimb locomotion within 24 h. By contrast, the locomotor pattern of the untrained cats remained asymmetrical, and the hindlimb on the side of the hemisection was still deficient. This study highlights the beneficial role of locomotor training in facilitating bilateral and symmetrical functional plastic changes within the spinal circuitry and in promoting locomotor recovery after an incomplete spinal cord injury.

  19. Locomotor function after long-duration space flight: effects and motor learning during recovery.

    PubMed

    Mulavara, Ajitkumar P; Feiveson, Alan H; Fiedler, James; Cohen, Helen; Peters, Brian T; Miller, Chris; Brady, Rachel; Bloomberg, Jacob J

    2010-05-01

    Astronauts returning from space flight and performing Earth-bound activities must rapidly transition from the microgravity-adapted sensorimotor state to that of Earth's gravity. The goal of the current study was to assess locomotor dysfunction and recovery of function after long-duration space flight using a test of functional mobility. Eighteen International Space Station crewmembers experiencing an average flight duration of 185 days performed the functional mobility test (FMT) pre-flight and post-flight. To perform the FMT, subjects walked at a self selected pace through an obstacle course consisting of several pylons and obstacles set up on a base of 10-cm-thick, medium-density foam for a total of six trials per test session. The primary outcome measure was the time to complete the course (TCC, in seconds). To assess the long-term recovery trend of locomotor function after return from space flight, a multilevel exponential recovery model was fitted to the log-transformed TCC data. All crewmembers exhibited altered locomotor function after space flight, with a median 48% increase in the TCC. From the fitted model we calculated that a typical subject would recover to 95% of his/her pre-flight level at approximately 15 days post-flight. In addition, to assess the early motor learning responses after returning from space flight, we modeled performance over the six trials during the first post-flight session by a similar multilevel exponential relation. We found a significant positive correlation between measures of long-term recovery and early motor learning (P < 0.001) obtained from the respective models. We concluded that two types of recovery processes influence an astronaut's ability to re-adapt to Earth's gravity environment. Early motor learning helps astronauts make rapid modifications in their motor control strategies during the first hours after landing. Further, this early motor learning appears to reinforce the adaptive realignment, facilitating re

  20. Locomotor function of the dorsal fin in teleost fishes: experimental analysis of wake forces in sunfish.

    PubMed

    Drucker, E G; Lauder, G V

    2001-09-01

    -third of the laterally directed fluid force measured during turning is developed by the soft dorsal fin. For steady swimming, we present empirical evidence that vortex structures generated by the soft dorsal fin upstream can constructively interact with those produced by the caudal fin downstream. Reinforcement of circulation around the tail through interception of the dorsal fin's vortices is proposed as a mechanism for augmenting wake energy and enhancing thrust. Swimming in fishes involves the partitioning of locomotor force among several independent fin systems. Coordinated use of the pectoral fins, caudal fin and soft dorsal fin to increase wake momentum, as documented for L. macrochirus, highlights the ability of teleost fishes to employ multiple propulsors simultaneously for controlling complex swimming behaviors.

  1. Increased Adaptation Rates and Reduction in Trial-by-Trial Variability in Subjects with Cerebral Palsy Following a Multi-session Locomotor Adaptation Training

    PubMed Central

    Mawase, Firas; Bar-Haim, Simona; Joubran, Katherin; Rubin, Lihi; Karniel, Amir; Shmuelof, Lior

    2016-01-01

    Cerebral Palsy (CP) results from an insult to the developing brain and is associated with deficits in locomotor and manual skills and in sensorimotor adaptation. We hypothesized that the poor sensorimotor adaptation in persons with CP is related to their high execution variability and does not reflect a general impairment in adaptation learning. We studied the interaction between performance variability and adaptation deficits using a multi-session locomotor adaptation design in persons with CP. Six adolescents with diplegic CP were exposed, during a period of 15 weeks, to a repeated split-belt treadmill perturbation spread over 30 sessions and were tested again 6 months after the end of training. Compared to age-matched healthy controls, subjects with CP showed poor adaptation and high execution variability in the first exposure to the perturbation. Following training they showed marked reduction in execution variability and an increase in learning rates. The reduction in variability and the improvement in adaptation were highly correlated in the CP group and were retained 6 months after training. Interestingly, despite reducing their variability in the washout phase, subjects with CP did not improve learning rates during washout phases that were introduced only four times during the experiment. Our results suggest that locomotor adaptation in subjects with CP is related to their execution variability. Nevertheless, while variability reduction is generalized to other locomotor contexts, the development of savings requires both reduction in execution variability and multiple exposures to the perturbation. PMID:27199721

  2. Regulatory modes and time management: how locomotors and assessors plan and perceive time.

    PubMed

    Amato, Clara; Pierro, Antonio; Chirumbolo, Antonio; Pica, Gennaro

    2014-06-01

    This research investigated the relationship between regulatory mode orientations (locomotion and assessment), time management behaviours and the perceived control of time. "Locomotion" refers to the aspect of self-regulation involving the movement from state to state, whereas "assessment" is the comparative aspect of self-regulation that refers to the critical evaluation of alternative goals and the means for achieving them. The Italian versions of the Time Management Behavior Scale and the Perceived Control of Time Scale, as well as the Locomotion and Assessment Regulatory Modes Scales were administered to 339 Italian participants (249 students and 90 employees). The results supported the notion that locomotors and assessors differ in the ways they perceive the control of time. Locomotion was found to be positively related to perceived control of time. In contrast, assessment was negatively related to perceived control of time. Furthermore, the two time management dimensions of setting goals and priorities and preference for organisation were shown to mediate the relationship between locomotion and perceived control of time, whereas assessment proved to be unrelated to all time management behaviours. These findings highlight the importance of regulatory modes for human behaviour regarding time management and perceived control of time.

  3. Neurotensin and bombesin, a relationship between their effects on body temperature and locomotor activity?

    PubMed

    van Wimersma Greidanus, T B; Schijff, J A; Noteboom, J L; Spit, M C; Bruins, L; van Zummeren, B M; Rinkel, G J

    1984-08-01

    Neurotensin and bombesin have been tested for their effects on body temperature and locomotor activity in an open field. Both peptides induce hypothermia and suppress ambulation and rearing. The time curves of the hypothermic effects of both peptides appear to be rather similar, although bombesin is a more potent hypothermic agent than neurotensin. The time curves of the effects on locomotor activity appear to be quite different. The suppressive effect of neurotensin on locomotor activity is relatively short lasting and reaches its maximum at approximately 32 minutes. The effect of bombesin follows a different time curve and shows two peaks, suggesting that two different mechanisms are involved in the suppressive action of bombesin on locomotor activity. Calculation of the correlation coefficients between the effects of neurotensin and of bombesin on body temperature and on locomotor activity (ambulation) suggest that a causal relationship between these two effects is not likely, in particular for neurotensin.

  4. Locomotor Trajectories of Stroke Patients during Oriented Gait and Turning

    PubMed Central

    Van Hamme, Angele; Bensmail, Djamel

    2016-01-01

    Background The Timed Up and Go (TUG) test is widely used to assess locomotion in patients with stroke and is considered to predict the risk of falls. The analysis of locomotor trajectories during the TUG appears pertinent in stroke patients. The aims of this study were i) to analyze locomotor trajectories in patients with stroke during the walking and turning sub-tasks of the TUG, and to compare them with healthy subjects, ii) to determine whether trajectory parameters provide additional information to that provided by the conventional measure (performance time), iii) to compare the trajectory parameters of fallers and non-fallers with stroke and of patients with right and left hemisphere stroke, and iv) to evaluate correlations between trajectory parameters and Berg Balance Scale scores. Methods 29 patients with stroke (mean age 54.2±12.2 years, 18 men, 8 fallers) and 25 healthy subjects (mean age 51.6±8.7 years, 11 men) underwent three-dimensional analysis of the TUG. The trajectory of the center of mass was analyzed by calculation of the global trajectory length, Hausdorff distance and Dynamic Time Warping. The parameters were compared with a reference trajectory during the total task and each sub-task (Go, Turn, Return) of the TUG. Results Values of trajectory parameters were significantly higher for the stroke group during the total TUG and the Go and Turn sub-tasks (p<0.05). Moreover, logistic regression indicated that these parameters better discriminated stroke patients and healthy subjects than the conventional timed performance during the Go sub-task. In addition, fallers were distinguished by higher Dynamic Time Warping during the Go (p<0.05). There were no differences between patients with right and left hemisphere stroke. Discussion and Conclusion The trajectories of the stroke patients were longer and more deviated during the turn and the preceding phase. Trajectory parameters provided additional information to timed performance of this locomotor

  5. Evaluating the SCC resistance of underwater welds in sodium tetrathionate

    SciTech Connect

    White, R.A.; Angeliu, T.M.

    1997-12-01

    The susceptibility of welds to stress corrosion cracking (SCC) is enhanced by the surface residual tensile stresses generated by the typical welding process. However, underwater plasma transferred arc (PTA) welding has been shown to produce compressive surface residual stresses, an encouraging result if repairs of cracked boiling water reactor (BWR) components are to be made without further endangering them to SCC. This program was designed to verify that underwater PTA welds are resistant to SCC and to determine if underwater PTA welding could mitigate SCC in potentially susceptible welds. This was achieved by exposing various welds on solution annealed (SA) and SA + thermally sensitized 304 stainless steel at 25 C in a solution of 1.5 gm/liter of sodium sulfide added to 0.05M sodium tetrathionate, titrated to a pH of 1.25 with H{sub 2}SO{sub 4}. The autogeneous welds were produced using gas tungsten arc (GTA) and plasma transferred arc (PTA) welding under atmospheric conditions, and PTA welding underwater. After 1 hour of sodium tetrathionate exposure, GTA and air PTA welds exhibited SCC while the underwater PTA weld heat affected zones were more resistant. Underwater PTA welds bisecting a GTA weld eliminated the cracking in the GTA weld heat affected zone under certain conditions. The lack of IG cracking in the region influenced by the underwater PTA weld is consistent with the measurement of compressive surface residual stresses inherent to the underwater welding process.

  6. Relaxation effects in humans of underwater exercise of moderate intensity.

    PubMed

    Oda, S; Matsumoto, T; Nakagawa, K; Moriya, K

    1999-09-01

    In this study we investigated the effects of underwater exercise in warm water (34 degrees C) on physiological and psychological relaxation. Eight healthy young men (aged 20-26 years) volunteered for the experiment. The experiment consisted of the following three successive segments: a pre-exercise period of 20 min, during which the subjects rested in a semi-supine posture with their eyes closed for the final 10 min; an underwater exercise period of approximately 60 min, during which the subjects performed gymnastic exercises or aerobic dancing with occasional movements or jumping; a post-exercise recovery of 20 min, which was similar to the pre-exercise rest period. We compared the relative power values (power %) of the electroencephalogram alpha bands (8-13 Hz) and profile of moods states (POMS) before and after the underwater exercise. We also estimated the percentage of maximal heart rate (%HRmax) throughout the experiment to ascertain the intensity of the underwater exercise. The results of %HRmax indicated that the intensity of underwater exercises practised in the experiments ranged from low to moderate. The power % of EEG alpha bands had increased significantly after the underwater exercise compared with the pre-exercise rest (P<0.05). From the POMS results, we observed that positive mood (vigour) increased and negative mood (tension and anxiety, depression and dejection) decreased significantly after the underwater exercise (P<0.05). This study found that the subjects showed increased physiological and psychological indices of relaxation after underwater exercise.

  7. Elastic Wave Propagation Mechanisms in Underwater Acoustic Environments

    DTIC Science & Technology

    2015-09-30

    Elastic wave propagation mechanisms in underwater acoustic environments Scott D. Frank Marist College Department of Mathematics Poughkeepsie...conversion from elastic propagation to acoustic propagation, and intense interface waves on underwater acoustic environments with elastic bottoms... acoustic energy in the water column. Elastic material parameters will be varied for analysis of the dissipation of water column acoustic energy

  8. 76 FR 52734 - Underwater Locating Devices (Acoustic) (Self-Powered)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-23

    ...This notice announces the planned revocation of all Technical Standard Order authorizations (TSOA) issued for the production of Underwater Locating Devices (Acoustic) (Self-Powered) manufactured to the TSO-C121 and TSO-C121a specifications. These actions are necessary because the planned issuance of TSO-C121b, Underwater Locating Devices (Acoustic) (Self-Powered), with a minimum performance......

  9. 77 FR 13174 - Underwater Locating Devices (Acoustic) (Self-Powered)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-05

    ...This is a confirmation notice for the planned revocation of all Technical Standard Order authorizations issued for the production of Underwater Locating Devices (Acoustic) (Self-Powered) manufactured to the TSO-C121 and TSO-C121a specifications. These actions are necessary because the planned issuance of TSO-C121b, Underwater Locating Devices (Acoustic) (Self-Powered), minimum performance......

  10. Visual-adaptation-mechanism based underwater object extraction

    NASA Astrophysics Data System (ADS)

    Chen, Zhe; Wang, Huibin; Xu, Lizhong; Shen, Jie

    2014-03-01

    Due to the major obstacles originating from the strong light absorption and scattering in a dynamic underwater environment, underwater optical information acquisition and processing suffer from effects such as limited range, non-uniform lighting, low contrast, and diminished colors, causing it to become the bottleneck for marine scientific research and projects. After studying and generalizing the underwater biological visual mechanism, we explore its advantages in light adaption which helps animals to precisely sense the underwater scene and recognize their prey or enemies. Then, aiming to transform the significant advantage of the visual adaptation mechanism into underwater computer vision tasks, a novel knowledge-based information weighting fusion model is established for underwater object extraction. With this bionic model, the dynamical adaptability is given to the underwater object extraction task, making them more robust to the variability of the optical properties in different environments. The capability of the proposed method to adapt to the underwater optical environments is shown, and its outperformance for the object extraction is demonstrated by comparison experiments.

  11. Evaluation of Computational Codes for Underwater Hull Analysis Model Applications

    DTIC Science & Technology

    2014-02-05

    Elsyca CP Master was selected as the best basis for the Underwater Hull Analysis Model; however, additional work performed with COMSOL Multiphysics...since the selection indicates that COMSOL should be re-evaluated if the Underwater Hull Analysis Model program is renewed at some future date. 05-02...8 4.3 COMSOL MULTIPHYSICS ......................................................................................... 10 4.4 ELSYCA CP

  12. Underwater Chaotic Lidar using Blue Laser Diodes

    NASA Astrophysics Data System (ADS)

    Rumbaugh, Luke K.

    The thesis proposes and explores an underwater lidar system architecture based on chaotic modulation of recently introduced, commercially available, low cost blue laser diodes. This approach is experimentally shown to allow accurate underwater impulse response measurements while eliminating the need for several major components typically found in high-performance underwater lidar systems. The proposed approach is to: 1. Generate wideband, noise-like intensity modulation signals using optical chaotic modulation of blue-green laser diodes, and then 2. Use this signal source to develop an underwater chaotic lidar system that uses no electrical signal generator, no electro-optic modulator, no optical frequency doubler, and no large-aperture photodetector. The outcome of this thesis is the demonstration of a new underwater lidar system architecture that could allow high resolution ranging, imaging, and water profiling measurements in turbid water, at a reduced size, weight, power and cost relative to state-of-the-art high-performance underwater lidar sensors. This work also makes contributions to the state of the art in optics, nonlinear dynamics, and underwater sensing by demonstrating for the first time: 1. Wideband noise-like intensity modulation of a blue laser diode using no electrical signal generator or electro-optic modulator. Optical chaotic modulation of a 462 nm blue InGaN laser diode by self-feedback is explored for the first time. The usefulness of the signal to chaotic lidar is evaluated in terms of bandwidth, modulation depth, and autocorrelation peak-to-sidelobe-ratio (PSLR) using both computer and laboratory experiments. In laboratory experiments, the optical feedback technique is shown to be effective in generating wideband, noise-like chaotic signals with strong modulation depth when the diode is operated in an external-cavity dominated state. The modulation signal strength is shown to be limited by the onset of lasing within the diode's internal

  13. Biological Response to the Dynamic Spectral-Polarized Underwater Light Field

    DTIC Science & Technology

    2010-01-01

    underwater spectral-polarized light field in oligotrophic and eutrophic systems (2) Quantify the biological response in fish and cephalopods to these...and cephalopods Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the collection of information is estimated to...internal control features regulating camouflage in both fish and cephalopods . We will also develop a novel use of Mueller matrix modeling to calculate

  14. Underwater plasma discharge and its water treatment applications

    NASA Astrophysics Data System (ADS)

    Ma, Sukhwal; Huh, Jin Young; Kim, Kangil; Hong, Yong Cheol; National Fusion Research Institute Team; Chonbuk National University Team; Kwangwoon University Team; NPAC Team

    2016-09-01

    In recent, the quality of water has been exacerbated by the influx of wastewater and water pollutants. There have been frequent occurrences of water blooms due to the eutrophication of river. Therefore, the needs for water treatment are increased through effective and environment-friendly method. In this work, we propose the plasma system to overcome the problems mentioned above using underwater discharge plasma. The underwater discharges are generated by capillary electrode, and have the advantages of low cost, high efficiency and eco-friendly processing. The proposed technologies can be suitable for eliminating cyanobacteria, decreasing the concentration of oil dissolved in water, and purifying wastewater. Cyanobacteria is killed directly by the underwater discharge and water-dissolved oil and heavy-metal wastewater are purified by coagulation effect, which may result from the chemical reactions of underwater plasma. Consequently, these technologies using underwater discharge can be alternative methods to replace the existing technologies.

  15. On Modeling Eavesdropping Attacks in Underwater Acoustic Sensor Networks †

    PubMed Central

    Wang, Qiu; Dai, Hong-Ning; Li, Xuran; Wang, Hao; Xiao, Hong

    2016-01-01

    The security and privacy of underwater acoustic sensor networks has received extensive attention recently due to the proliferation of underwater activities. This paper proposes an analytical model to investigate the eavesdropping attacks in underwater acoustic sensor networks. Our analytical framework considers the impacts of various underwater acoustic channel conditions (such as the acoustic signal frequency, spreading factor and wind speed) and different hydrophones (isotropic hydrophones and array hydrophones) in terms of network nodes and eavesdroppers. We also conduct extensive simulations to evaluate the effectiveness and the accuracy of our proposed model. Empirical results show that our proposed model is quite accurate. In addition, our results also imply that the eavesdropping probability heavily depends on both the underwater acoustic channel conditions and the features of hydrophones. PMID:27213379

  16. Design and implementation of an underwater sound recording device

    SciTech Connect

    Martinez, Jayson J.; Myers, Joshua R.; Carlson, Thomas J.; Deng, Zhiqun; Rohrer, John S.; Caviggia, Kurt A.

    2011-09-19

    The purpose of this study was to design and build two versions of an underwater sound recording device. The device designed is referred to as the Underwater Sound Recorder (USR), which can be connected to one or two hydrophones or other underwater sound sensors. The URS contains a 26 dB preamplifier and a user selectable gain that permits additional amplification of input to the system from 26 dB to 46 dB. Signals within the frequency range up to 15 kHz may be recorded using the USR. Examples of USR applications are monitoring underwater processes that have the potential to create large pressure waves that could potentially harm fish or other aquatic life, such as underwater explosions or pile driving. Additional applications are recording sound generated by vessels or the vocalizations of some marine mammals, such as the calls from many species of whales.

  17. Strong, reversible underwater adhesion via gecko-inspired hydrophobic fibers.

    PubMed

    Soltannia, Babak; Sameoto, Dan

    2014-12-24

    Strong, reversible underwater adhesion using gecko-inspired surfaces is achievable through the use of a hydrophobic structural material and does not require surface modification or suction cup effects for this adhesion to be effective. Increased surface energy can aid in dry adhesion in an air environment but strongly degrades wet adhesion via reduction of interfacial energy underwater. A direct comparison of structurally identical but chemically different mushroom shaped fibers shows that strong, reversible adhesion, even in a fully wetted, stable state, is feasible underwater if the structural material of the fibers is hydrophobic and the mating surface is not strongly hydrophilic. The exact adhesion strength will be a function of the underwater interfacial energy between surfaces and the specific failure modes of individual fibers. This underwater adhesion has been calculated to be potentially greater than the dry adhesion for specific combinations of hydrophobic surfaces.

  18. On Modeling Eavesdropping Attacks in Underwater Acoustic Sensor Networks.

    PubMed

    Wang, Qiu; Dai, Hong-Ning; Li, Xuran; Wang, Hao; Xiao, Hong

    2016-05-18

    The security and privacy of underwater acoustic sensor networks has received extensive attention recently due to the proliferation of underwater activities. This paper proposes an analytical model to investigate the eavesdropping attacks in underwater acoustic sensor networks. Our analytical framework considers the impacts of various underwater acoustic channel conditions (such as the acoustic signal frequency, spreading factor and wind speed) and different hydrophones (isotropic hydrophones and array hydrophones) in terms of network nodes and eavesdroppers. We also conduct extensive simulations to evaluate the effectiveness and the accuracy of our proposed model. Empirical results show that our proposed model is quite accurate. In addition, our results also imply that the eavesdropping probability heavily depends on both the underwater acoustic channel conditions and the features of hydrophones.

  19. Pilot study of Lokomat versus manual-assisted treadmill training for locomotor recovery post-stroke

    PubMed Central

    Westlake, Kelly P; Patten, Carolynn

    2009-01-01

    Background While manually-assisted body-weight supported treadmill training (BWSTT) has revealed improved locomotor function in persons with post-stroke hemiparesis, outcomes are inconsistent and it is very labor intensive. Thus an alternate treatment approach is desirable. Objectives of this pilot study were to: 1) compare the efficacy of body-weight supported treadmill training (BWSTT) combined with the Lokomat robotic gait orthosis versus manually-assisted BWSTT for locomotor training post-stroke, and 2) assess effects of fast versus slow treadmill training speed. Methods Sixteen volunteers with chronic hemiparetic gait (0.62 ± 0.30 m/s) post-stroke were randomly allocated to Lokomat (n = 8) or manual-BWSTT (n = 8) 3×/wk for 4 weeks. Groups were also stratified by fast (mean 0.92 ± 0.15 m/s) or slow (0.58 ± 0.12 m/s) training speeds. The primary outcomes were self-selected overground walking speed and paretic step length ratio. Secondary outcomes included: fast overground walking speed, 6-minute walk test, and a battery of clinical measures. Results No significant differences in primary outcomes were revealed between Lokomat and manual groups as a result of training. However, within the Lokomat group, self-selected walk speed, paretic step length ratio, and four of the six secondary measures improved (p = 0.04–0.05, effect sizes = 0.19–0.60). Within the manual group, only balance scores improved (p = 0.02, effect size = 0.57). Group differences between fast and slow training groups were not revealed (p ≥ 0.28). Conclusion Results suggest that Lokomat training may have advantages over manual-BWSTT following a modest intervention dose in chronic hemiparetic persons and further, that our training speeds produce similar gait improvements. Suggestions for a larger randomized controlled trial with optimal study parameters are provided. PMID:19523207

  20. Spontaneous locomotor activity in late-stage chicken embryos is modified by stretch of leg muscles

    PubMed Central

    Bradley, Nina S.; Ryu, Young U.; Yeseta, Marie C.

    2014-01-01

    Chicks initiate bilateral alternating steps several days before hatching and adaptively walk within hours of hatching, but emergence of precocious walking skills is not well understood. One of our aims was to determine whether interactions between environment and movement experience prior to hatching are instrumental in establishing precocious motor skills. However, physiological evidence of proprioceptor development in the chick has yet to be established; thus, one goal of this study was to determine when in embryogenesis proprioception circuits can code changes in muscle length. A second goal was to determine whether proprioception circuits can modulate leg muscle activity during repetitive limb movements for stepping (RLMs). We hypothesized that proprioception circuits code changes in muscle length and/or tension, and modulate locomotor circuits producing RLMs in anticipation of adaptive locomotion at hatching. To this end, leg muscle activity and kinematics were recorded in embryos during normal posture and after fitting one ankle with a restraint that supported the limb in an atypical posture. We tested the hypotheses by comparing leg muscle activity during spontaneous RLMs in control posture and ankle extension restraint. The results indicated that proprioceptors detect changes in muscle length and/or muscle tension 3 days before hatching. Ankle extension restraint produced autogenic excitation of the ankle flexor and reciprocal inhibition of the ankle extensor. Restraint also modified knee extensor activity during RLMs 1 day before hatching. We consider the strengths and limitations of these results and propose that proprioception contributes to precocious locomotor development during the final 3 days before hatching. PMID:24265423

  1. Vestibular lesion-induced developmental plasticity in spinal locomotor networks during Xenopus laevis metamorphosis.

    PubMed

    Beyeler, Anna; Rao, Guillaume; Ladepeche, Laurent; Jacques, André; Simmers, John; Le Ray, Didier

    2013-01-01

    During frog metamorphosis, the vestibular sensory system remains unchanged, while spinal motor networks undergo a massive restructuring associated with the transition from the larval to adult biomechanical system. We investigated in Xenopus laevis the impact of a pre- (tadpole stage) or post-metamorphosis (juvenile stage) unilateral labyrinthectomy (UL) on young adult swimming performance and underlying spinal locomotor circuitry. The acute disruptive effects on locomotion were similar in both tadpoles and juvenile frogs. However, animals that had metamorphosed with a preceding UL expressed restored swimming behavior at the juvenile stage, whereas animals lesioned after metamorphosis never recovered. Whilst kinematic and electrophysiological analyses of the propulsive system showed no significant differences in either juvenile group, a 3D biomechanical simulation suggested that an asymmetry in the dynamic control of posture during swimming could account for the behavioral restoration observed in animals that had been labyrinthectomized before metamorphosis. This hypothesis was subsequently supported by in vivo electromyography during free swimming and in vitro recordings from isolated brainstem/spinal cord preparations. Specifically, animals lesioned prior to metamorphosis at the larval stage exhibited an asymmetrical propulsion/posture coupling as a post-metamorphic young adult. This developmental alteration was accompanied by an ipsilesional decrease in propriospinal coordination that is normally established in strict left-right symmetry during metamorphosis in order to synchronize dorsal trunk muscle contractions with bilateral hindlimb extensions in the swimming adult. Our data thus suggest that a disequilibrium in descending vestibulospinal information during Xenopus metamorphosis leads to an altered assembly of adult spinal locomotor circuitry. This in turn enables an adaptive compensation for the dynamic postural asymmetry induced by the vestibular imbalance

  2. Variability in step training enhances locomotor recovery after a spinal cord injury.

    PubMed

    Shah, Prithvi K; Gerasimenko, Yury; Shyu, Andrew; Lavrov, Igor; Zhong, Hui; Roy, Roland R; Edgerton, Victor R

    2012-07-01

    Performance of a motor task is improved by practicing a specific task with added 'challenges' to a training regimen. We tested the hypothesis that, in the absence of brain control, the performance of a motor task is enhanced by training using specific variations of that task. We utilized modifications of step performance training to improve the ability of spinal rats to forward step. After a complete thoracic spinal cord transection, 20 adult rats were divided randomly to bipedally step on a treadmill in the forward, sideward, or backward direction for 28 sessions (20 min, 5 days/week) and subsequently tested for their ability to step in the forward direction. Although the animals from all trained groups showed improvement, the rats in the sideward-trained and backward-trained groups had greater step consistency and coordination along with higher peak amplitudes and total integrated activity of the rectified electromyographic signals from selected hindlimb muscles per step during forward stepping than the rats in the forward-trained group. Our results demonstrate that, by retaining the fundamental features of a motor task (bipedal stepping), the ability to perform that motor task can be enhanced by the addition of specific contextual variations to the task (direction of stepping). Our data suggest that the forward stepping neuronal locomotor networks are partially complemented by synchronous activation of interneuronal/motoneuronal populations that are also a part of the sideward or backward stepping locomotor networks. Accordingly, the overlap and interaction of neuronal elements may play a critical role in positive task transference.

  3. Exaggerated sympathetic and cardiovascular responses to stimulation of the mesencephalic locomotor region in spontaneously hypertensive rats

    PubMed Central

    Liang, Nan; Mitchell, Jere H.; Smith, Scott A.

    2015-01-01

    The sympathetic and pressor responses to exercise are exaggerated in hypertension. However, the underlying mechanisms causing this abnormality remain to be fully elucidated. Central command, a neural drive originating in higher brain centers, is known to activate cardiovascular and locomotor control circuits concomitantly. As such, it is a viable candidate for the generation of the augmented vascular response to exercise in this disease. We hypothesized that augmentations in central command function contribute to the heightened cardiovascular response to exercise in hypertension. To test this hypothesis, changes in renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) in response to electrical stimulation of mesencephalic locomotor region (MLR; 20–50 μA in 10-μA steps evoking fictive locomotion), a putative component of the central command pathway, were examined in decerebrate, paralyzed normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). Tibial nerve discharge during MLR stimulation significantly increased in an intensity-dependent manner in both WKY and SHR but was not different between groups. Stimulation of the MLR evoked significantly larger increases in RSNA and MAP with increasing stimulation intensity in both groups. Importantly, the increases in sympathetic and pressor responses to this fictive locomotion were significantly greater in SHR compared with WKY across all stimulation intensities (e.g., at 50 μA, ΔRSNA: WKY 153±31%, SHR 287±42%; ΔMAP: WKY 87±9 mmHg, SHR 139±7 mmHg). These findings provide the first evidence that central command may be a critical contributor to the exaggerated rise in sympathetic activity and blood pressure during exercise in hypertension. PMID:26545711

  4. Development and neuromodulation of spinal locomotor networks in the metamorphosing frog.

    PubMed

    Rauscent, Aude; Le Ray, Didier; Cabirol-Pol, Marie-Jeanne; Sillar, Keith T; Simmers, John; Combes, Denis

    2006-01-01

    Metamorphosis in the anuran frog, Xenopus laevis, involves profound structural and functional transformations in most of the organism's physiological systems as it encounters a complete alteration in body plan, habitat, mode of respiration and diet. The metamorphic process also involves a transition in locomotory strategy from axial-based undulatory swimming using alternating contractions of left and right trunk muscles, to bilaterally-synchronous kicking of the newly developed hindlimbs in the young adult. At critical stages during this behavioural switch, functional larval and adult locomotor systems co-exist in the same animal, implying a progressive and dynamic reconfiguration of underlying spinal circuitry and neuronal properties as limbs are added and the tail regresses. To elucidate the neurobiological basis of this developmental process, we use electrophysiological, pharmacological and neuroanatomical approaches to study isolated in vitro brain stem/spinal cord preparations at different metamorphic stages. Our data show that the emergence of secondary limb motor circuitry, as it supersedes the primary larval network, spans a developmental period when limb circuitry is present but not functional, functional but co-opted into the axial network, functionally separable from the axial network, and ultimately alone after axial circuitry disappears with tail resorption. Furthermore, recent experiments on spontaneously active in vitro preparations from intermediate metamorphic stage animals have revealed that the biogenic amines serotonin (5-HT) and noradrenaline (NA) exert short-term adaptive control over circuit activity and inter-network coordination: whereas bath-applied 5-HT couples axial and appendicular rhythms into a single unified pattern, NA has an opposite decoupling effect. Moreover, the progressive and region-specific appearance of spinal cord neurons that contain another neuromodulator, nitric oxide (NO), suggests it plays a role in the maturation of

  5. Cardiovascular responses to locomotor activity and feeding in unrestrained three-toed sloths, Bradypus variegatus.

    PubMed

    Duarte, D P F; Jaguaribe, A M; Pedrosa, M A C; Clementino, A C C R; Barbosa, A A; Silva, A F V; Gilmore, D P; Da Costa, C P

    2004-10-01

    Heart rate (HR) and systolic (SBP), diastolic (DBP) and mean (MBP) blood pressure were recorded by biotelemetry in nine conscious unrestrained sloths for 1 min every 15 min over a 24-h period. The animals were allowed to freely move in an acoustically isolated and temperature-controlled (24 +/- 1 degree C) experimental room with light-dark cycle (12/12 h). Behavior was closely monitored through a unidirectional visor and classified as resting (sitting or suspended), feeding (chewing and swallowing embauba leaves, Cecropia adenops), or locomotor activity around the tree trunk or on the room floor. Locomotor activity caused statistically significant increases in SBP (+8%, from 121 +/- 22 to 131 +/- 18 mmHg), DBP (+7%, from 86 +/- 17 to 92 +/- 10 mmHg), MBP (+8%, from 97 +/- 19 to 105 +/- 12 mmHg), and HR (+14%, from 84 +/- 15 to 96 +/- 15 bpm) compared to resting values, indicating a possible major influence of the autonomic nervous system on the modulation of cardiac function during this behavior. During feeding, the increase in blood pressure was even higher (SBP +27%, from 119 +/- 21 to 151 +/- 21 mmHg; DBP +21%, from 85 +/- 16 to 103 +/- 15 mmHg; MBP +24%, from 96 +/- 17 to 119 +/- 17 mmHg), while HR remained at 14% (from 84 +/- 15 to 96 +/- 10 bpm) above resting values. The proportionally greater increase in blood pressure than in HR during feeding suggests an increase in peripheral vascular resistance as part of the overall response to this behavior.

  6. Exaggerated sympathetic and cardiovascular responses to stimulation of the mesencephalic locomotor region in spontaneously hypertensive rats.

    PubMed

    Liang, Nan; Mitchell, Jere H; Smith, Scott A; Mizuno, Masaki

    2016-01-01

    The sympathetic and pressor responses to exercise are exaggerated in hypertension. However, the underlying mechanisms causing this abnormality remain to be fully elucidated. Central command, a neural drive originating in higher brain centers, is known to activate cardiovascular and locomotor control circuits concomitantly. As such, it is a viable candidate for the generation of the augmented vascular response to exercise in this disease. We hypothesized that augmentations in central command function contribute to the heightened cardiovascular response to exercise in hypertension. To test this hypothesis, changes in renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) in response to electrical stimulation of mesencephalic locomotor region (MLR; 20-50 μA in 10-μA steps evoking fictive locomotion), a putative component of the central command pathway, were examined in decerebrate, paralyzed normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). Tibial nerve discharge during MLR stimulation significantly increased in an intensity-dependent manner in both WKY and SHR but was not different between groups. Stimulation of the MLR evoked significantly larger increases in RSNA and MAP with increasing stimulation intensity in both groups. Importantly, the increases in sympathetic and pressor responses to this fictive locomotion were significantly greater in SHR compared with WKY across all stimulation intensities (e.g., at 50 μA, ΔRSNA: WKY 153 ± 31%, SHR 287 ± 42%; ΔMAP: WKY 87 ± 9 mmHg, SHR 139 ± 7 mmHg). These findings provide the first evidence that central command may be a critical contributor to the exaggerated rise in sympathetic activity and blood pressure during exercise in hypertension.

  7. Cool running: locomotor performance at low body temperature in mammals

    PubMed Central

    Rojas, A. Daniella; Körtner, Gerhard; Geiser, Fritz

    2012-01-01

    Mammalian torpor saves enormous amounts of energy, but a widely assumed cost of torpor is immobility and therefore vulnerability to predators. Contrary to this assumption, some small marsupial mammals in the wild move while torpid at low body temperatures to basking sites, thereby minimizing energy expenditure during arousal. Hence, we quantified how mammalian locomotor performance is affected by body temperature. The three small marsupial species tested, known to use torpor and basking in the wild, could move while torpid at body temperatures as low as 14.8–17.9°C. Speed was a sigmoid function of body temperature, but body temperature effects on running speed were greater than those in an ectothermic lizard used for comparison. We provide the first quantitative data of movement at low body temperature in mammals, which have survival implications for wild heterothermic mammals, as directional movement at low body temperature permits both basking and predator avoidance. PMID:22675136

  8. Cool running: locomotor performance at low body temperature in mammals.

    PubMed

    Rojas, A Daniella; Körtner, Gerhard; Geiser, Fritz

    2012-10-23

    Mammalian torpor saves enormous amounts of energy, but a widely assumed cost of torpor is immobility and therefore vulnerability to predators. Contrary to this assumption, some small marsupial mammals in the wild move while torpid at low body temperatures to basking sites, thereby minimizing energy expenditure during arousal. Hence, we quantified how mammalian locomotor performance is affected by body temperature. The three small marsupial species tested, known to use torpor and basking in the wild, could move while torpid at body temperatures as low as 14.8-17.9°C. Speed was a sigmoid function of body temperature, but body temperature effects on running speed were greater than those in an ectothermic lizard used for comparison. We provide the first quantitative data of movement at low body temperature in mammals, which have survival implications for wild heterothermic mammals, as directional movement at low body temperature permits both basking and predator avoidance.

  9. Tarsier-like locomotor specializations in the Oligocene primate Afrotarsius

    PubMed Central

    Rasmussen, D. Tab; Conroy, Glenn C.; Simons, Elwyn L.

    1998-01-01

    Tarsiers and extinct tarsier-like primates have played a central role in views of primate phylogeny and evolution for more than a century. Because of the importance of tarsiers in so many primatological problems, there has been particular interest in questions about the origin of tarsier specializations and the biogeography of early tarsioid radiations. We report on a new fossil of rare Afrotarsius that shows near identity to modern Tarsius in unique specializations of the leg, which provides information about the locomotor behavior and clarifies the phylogenetic position of this previously controversial primate. These specializations constitute evidence that Afrotarsius is a tarsiid, closely related to extant Tarsius; hence, it is now excluded from being a generalized sister taxon to Anthropoidea. PMID:9843978

  10. What does autonomic arousal tell us about locomotor learning?

    PubMed

    Green, D A; Bunday, K L; Bowen, J; Carter, T; Bronstein, A M

    2010-09-29

    Walking onto a stationary sled previously experienced as moving induces locomotor aftereffects (LAE, or "broken escalator phenomenon"). This particular form of aftereffect can develop after a single adaptation trial and occurs despite subjects being fully aware that the sled will not move. Here, we investigate whether such strong LAE expression may relate to arousal or fear related to instability during the gait adaptation process. Forty healthy subjects were allocated to three sled velocity groups; SLOW (0.6 m/s), MEDIUM (1.3 m/s), or FAST (2.0 m/s). Subjects walked onto the stationary sled for five trials (BEFORE), then onto the moving sled for 15 trials (adaptation or MOVING trials) and, finally, again onto the stationary sled for five trials (AFTER). Explicit warning regarding sled status was given. Trunk position, foot-sled contact timing, autonomic markers (electrodermal activity [EDA], ECG, respiratory movements) in addition to self-reported task-related confidence and state/trait anxiety were recorded. Trunk sway, EDA, and R-R interval shortening were greatest during the first MOVING trial (MOVING_1), progressively attenuating during subsequent MOVING trials. A LAE, recorded as increased gait velocity and trunk sway during AFTER_1, occurred in both MEDIUM and FAST sled velocity groups. The amplitude of forward trunk sway in AFTER_1 (an indicator of aftereffect magnitude) was related to EDA during the final adaptation trial (MOVING_15). AFTER_1 gait velocity (also an indicator of aftereffect magnitude) was related to MOVING_1 trunk sway. Hence, gait velocity and trunk sway components of the LAE are differentially related to kinematic and autonomic parameters during the early and late adaptation phase. The finding that EDA is a predictor of LAE expression indicates that autonomic arousal or fear-based mechanisms can promote locomotor learning. This could in turn explain some unusual characteristics of this LAE, namely its resistance to explicit knowledge and

  11. Pelvic Breadth and Locomotor Kinematics in Human Evolution.

    PubMed

    Gruss, Laura Tobias; Gruss, Richard; Schmitt, Daniel

    2017-04-01

    A broad pelvis is characteristic of most, if not all, pre-modern hominins. In at least some early australopithecines, most notably the female Australopithecus afarensis specimen known as "Lucy," it is very broad and coupled with very short lower limbs. In 1991, Rak suggested that Lucy's pelvic anatomy improved locomotor efficiency by increasing stride length through rotation of the wide pelvis in the axial plane. Compared to lengthening strides by increasing flexion and extension at the hips, this mechanism could avoid potentially costly excessive vertical oscillations of the body's center of mass (COM). Here, we test this hypothesis. We examined 3D kinematics of walking at various speeds in 26 adult subjects to address the following questions: Do individuals with wider pelves take longer strides, and do they use a smaller degree of hip flexion and extension? Is pelvic rotation greater in individuals with shorter legs, and those with narrower pelves? Our results support Rak's hypothesis. Subjects with wider pelves do take longer strides for a given velocity, and for a given stride length they flex and extend their hips less, suggesting a smoother pathway of the COM. Individuals with shorter legs do use more pelvic rotation when walking, but pelvic breadth was not related to pelvic rotation. These results suggest that a broad pelvis could benefit any bipedal hominin, but especially a short-legged australopithecine such as Lucy, by improving locomotor efficiency, particularly when carrying an infant or traveling in a foraging group with individuals of varying sizes. Anat Rec, 300:739-751, 2017. © 2017 Wiley Periodicals, Inc.

  12. Novel locomotor muscle design in extreme deep-diving whales.

    PubMed

    Velten, B P; Dillaman, R M; Kinsey, S T; McLellan, W A; Pabst, D A

    2013-05-15

    Most marine mammals are hypothesized to routinely dive within their aerobic dive limit (ADL). Mammals that regularly perform deep, long-duration dives have locomotor muscles with elevated myoglobin concentrations that are composed of predominantly large, slow-twitch (Type I) fibers with low mitochondrial volume densities (V(mt)). These features contribute to extending ADL by increasing oxygen stores and decreasing metabolic rate. Recent tagging studies, however, have challenged the view that two groups of extreme deep-diving cetaceans dive within their ADLs. Beaked whales (including Ziphius cavirostris and Mesoplodon densirostris) routinely perform the deepest and longest average dives of any air-breathing vertebrate, and short-finned pilot whales (Globicephala macrorhynchus) perform high-speed sprints at depth. We investigated the locomotor muscle morphology and estimated total body oxygen stores of several species within these two groups of cetaceans to determine whether they (1) shared muscle design features with other deep divers and (2) performed dives within their calculated ADLs. Muscle of both cetaceans displayed high myoglobin concentrations and large fibers, as predicted, but novel fiber profiles for diving mammals. Beaked whales possessed a sprinter's fiber-type profile, composed of ~80% fast-twitch (Type II) fibers with low V(mt). Approximately one-third of the muscle fibers of short-finned pilot whales were slow-twitch, oxidative, glycolytic fibers, a rare fiber type for any mammal. The muscle morphology of beaked whales likely decreases the energetic cost of diving, while that of short-finned pilot whales supports high activity events. Calculated ADLs indicate that, at low metabolic rates, both beaked and short-finned pilot whales carry sufficient onboard oxygen to aerobically support their dives.

  13. Reflection of underwater sound from surface waves.

    PubMed

    Tindle, Chris T; Deane, Grant B; Preisig, James C

    2009-01-01

    A tank experiment has been conducted to measure reflection of underwater sound from surface waves. Reflection from a wave crest leads to focusing and caustics and results in rapid variation in the received waveform as the surface wave moves. Theoretical results from wavefront modeling show that interference of three surface reflected eigenrays for each wave crest produces complicated interference waveforms. There is good agreement between theory and experiment even on the shadow side of caustics where there are two surface reflected arrivals but only one eigenray.

  14. Underwater Sound Propagation from Marine Pile Driving.

    PubMed

    Reyff, James A

    2016-01-01

    Pile driving occurs in a variety of nearshore environments that typically have very shallow-water depths. The propagation of pile-driving sound in water is complex, where sound is directly radiated from the pile as well as through the ground substrate. Piles driven in the ground near water bodies can produce considerable underwater sound energy. This paper presents examples of sound propagation through shallow-water environments. Some of these examples illustrate the substantial variation in sound amplitude over time that can be critical to understand when computing an acoustic-based safety zone for aquatic species.

  15. Underwater seismic source. [for petroleum exploration

    NASA Technical Reports Server (NTRS)

    Yang, L. C. (Inventor)

    1979-01-01

    Apparatus for generating a substantially oscillation-free seismic signal for use in underwater petroleum exploration, including a bag with walls that are flexible but substantially inelastic, and a pressured gas supply for rapidly expanding the bag to its fully expanded condition is described. The inelasticity of the bag permits the application of high pressure gas to rapidly expand it to full size, without requiring a venting mechanism to decrease the pressure as the bag approaches a predetermined size to avoid breaking of the bag.

  16. Caffeine stimulates locomotor activity in the mammalian spinal cord via adenosine A1 receptor-dopamine D1 receptor interaction and PKA-dependent mechanisms.

    PubMed

    Acevedo, JeanMarie; Santana-Almansa, Alexandra; Matos-Vergara, Nikol; Marrero-Cordero, Luis René; Cabezas-Bou, Ernesto; Díaz-Ríos, Manuel

    2016-02-01

    Caffeine is a potent psychostimulant that can have significant and widely variable effects on the activity of multiple neuronal pathways. The most pronounced caffeine-induced behavioral effect seen in rodents is to increase locomotor activity which has been linked to a dose-dependent inhibition of A1 and A(2A) receptors. The effects of caffeine at the level of the lumbar spinal central pattern generator (CPG) network for hindlimb locomotion are lacking. We assessed the effects of caffeine to the locomotor function of the spinal CPG network via extracellular ventral root recordings using the isolated neonatal mouse spinal cord preparation. Addition of caffeine and of an A1 receptor antagonist significantly decreased the cycle period accelerating the ongoing locomotor rhythm, while decreasing burst duration reversibly in most preparations suggesting the role of A1 receptors as the primary target of caffeine. Caffeine and an A1 receptor antagonist failed to stimulate ongoing locomotor activity in the absence of dopamine or in the presence of a D1 receptor antagonist supporting A1/D1 receptor-dependent mechanism of action. The use of caffeine or an A1 receptor blocker failed to stimulate an ongoing locomotor rhythm in the presence of a blocker of the cAMP-dependent protein kinase (PKA) supporting the need of this intracellular pathway for the modulatory effects of caffeine to occur. These results support a stimulant effect of caffeine on the lumbar spinal network controlling hindlimb locomotion through the inhibition of A1 receptors and subsequent activation of D1 receptors via a PKA-dependent intracellular mechanism.

  17. Suppression of Locomotor Activity in Female C57Bl/6J Mice Treated with Interleukin-1β: Investigating a Method for the Study of Fatigue in Laboratory Animals

    PubMed Central

    Bonsall, David R.; Kim, Hyunji; Tocci, Catherine; Ndiaye, Awa; Petronzio, Abbey; McKay-Corkum, Grace; Molyneux, Penny C.; Scammell, Thomas E.; Harrington, Mary E.

    2015-01-01

    Fatigue is a disabling symptom in patients with multiple sclerosis and Parkinson’s Disease, and is also common in patients with traumatic brain injury, cancer, and inflammatory disorders. Little is known about the neurobiology of fatigue, in part due to the lack of an approach to induce fatigue in laboratory animals. Fatigue is a common response to systemic challenge by pathogens, a response in part mediated through action of the pro-inflammatory cytokine interleukin-1 beta (IL-1β). We investigated the behavioral responses of mice to IL-1β. Female C57Bl/6J mice of 3 ages were administered IL-1β at various doses i.p. Interleukin-1β reduced locomotor activity, and sensitivity increased with age. Further experiments were conducted with middle-aged females. Centrally administered IL-1β dose-dependently reduced locomotor activity. Using doses of IL-1β that caused suppression of locomotor activity, we measured minimal signs of sickness, such as hyperthermia, pain or anhedonia (as measured with abdominal temperature probes, pre-treatment with the analgesic buprenorphine and through sucrose preference, respectively), all of which are responses commonly reported with higher doses. We found that middle-aged orexin-/- mice showed equivalent effects of IL-1β on locomotor activity as seen in wild-type controls, suggesting that orexins are not necessary for IL-1β -induced reductions in wheel-running. Given that the availability and success of therapeutic treatments for fatigue is currently limited, we examined the effectiveness of two potential clinical treatments, modafinil and methylphenidate. We found that these treatments were variably successful in restoring locomotor activity after IL-1β administration. This provides one step toward development of a satisfactory animal model of the multidimensional experience of fatigue, a model that could allow us to determine possible pathways through which inflammation induces fatigue, and could lead to novel treatments for

  18. Bioaccumulation and locomotor effects of manganese sulfate in Sprague-Dawley rats following subchronic (90 days) inhalation exposure

    SciTech Connect

    Tapin, Danielle; Kennedy, Greg; Lambert, Jean; Zayed, Joseph . E-mail: joseph.zayed@umontreal.ca

    2006-03-01

    Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic compound that was introduced as an antiknock additive to replace lead in unleaded fuel. The combustion of MMT results in the emission of fine Mn particulates mainly in the form of manganese sulfate and manganese phosphate. The objective of this study is to determine the effects of subchronic exposure to Mn sulfate in different tissues, on locomotor activity, on neuropathology, and on blood serum biochemical parameters. A control group and three groups of 30 male Sprague-Dawley rats were exposed 6-h/day, 5 days/week for 13 consecutive weeks at 30, 300, or 3000 {mu}g/m{sup 3} Mn sulfate. Locomotor activity was measured during 36 h using an Auto-Track System. Blood and the following tissues were collected and analyzed for manganese content by neutron activation analysis: olfactory bulb, globus pallidus, caudate/putamen, cerebellum, frontal cortex, liver, lung, testis, and kidney. Neuronal cell counts were obtained for the caudate/putamen and the globus pallidus and clinical biochemistry was assessed. Manganese concentrations were increased in blood, kidney, lung, and testis and in all brain regions in the 3000 {mu}g/m{sup 3} exposure group. Significant differences were also noted in the 300 {mu}g/m{sup 3} exposure group. Neuronal cell counts for the globus pallidus were significantly different between the two highest exposed groups and the controls. Locomotor activity for all exposure concentrations and resting time for the middle and highest concentrations for the two night resting periods were significantly increased. Total ambulatory count was decreased significantly for all exposure concentrations. Biochemical profiles also presented significant differences. No body weight loss was observed between all groups. These results suggest that neurotoxicity could occur at low exposure levels of Mn sulfate, one of the main combustion products of MMT.

  19. Cocaine-induced locomotor sensitization in rats correlates with nucleus accumbens activity on manganese-enhanced MRI.

    PubMed

    Perrine, Shane A; Ghoddoussi, Farhad; Desai, Kirtan; Kohler, Robert J; Eapen, Ajay T; Lisieski, Michael J; Angoa-Perez, Mariana; Kuhn, Donald M; Bosse, Kelly E; Conti, Alana C; Bissig, David; Berkowitz, Bruce A

    2015-11-01

    A long-standing goal of substance abuse research has been to link drug-induced behavioral outcomes with the activity of specific brain regions to understand the neurobiology of addiction behaviors and to search for drug-able targets. Here, we tested the hypothesis that cocaine produces locomotor (behavioral) sensitization that correlates with increased calcium channel-mediated neuroactivity in brain regions linked with drug addiction, such as the nucleus accumbens (NAC), anterior striatum (AST) and hippocampus, as measured using manganese-enhanced MRI (MEMRI). Rats were treated with cocaine for 5 days, followed by a 2-day drug-free period. The following day, locomotor sensitization was quantified as a metric of cocaine-induced neuroplasticity in the presence of manganese. Immediately following behavioral testing, rats were examined for changes in calcium channel-mediated neuronal activity in the NAC, AST, hippocampus and temporalis muscle, which was associated with behavioral sensitization using MEMRI. Cocaine significantly increased locomotor activity and produced behavioral sensitization compared with saline treatment of control rats. A significant increase in MEMRI signal intensity was determined in the NAC, but not AST or hippocampus, of cocaine-treated rats compared with saline-treated control rats. Cocaine did not increase signal intensity in the temporalis muscle. Notably, in support of our hypothesis, behavior was significantly and positively correlated with MEMRI signal intensity in the NAC. As neuronal uptake of manganese is regulated by calcium channels, these results indicate that MEMRI is a powerful research tool to study neuronal activity in freely behaving animals and to guide new calcium channel-based therapies for the treatment of cocaine abuse and dependence.

  20. Olfactory bulbectomy modifies photic entrainment and circadian rhythms of body temperature and locomotor activity in a nocturnal primate.

    PubMed

    Perret, Martine; Aujard, Fabienne; Séguy, Maud; Schilling, Alain

    2003-10-01

    Studies on rodents have emphasized that removal of the olfactory bulbs modulates circadian rhythmicity. Using telemetric recordings of both body temperature (Tb) and locomotor activity (LA) in a male nocturnal primate, the gray mouse lemur, the authors investigated the effects of olfactory bulbectomy on (1) the circadian periods of Tb and LA in constant dim light condition, and (2) photic re-entrainment rates of circadian rhythms following 6-h phase shifts of entrained light-dark cycle (LD 12:12). Under free-running condition, bulbectomized males had significantly shorter circadian periods of Tb and LA rhythms than those of control males. However, the profiles of Tb rhythms, characterized by a phase of hypothermia at the beginning of the subjective day, and Tb parameters were not modified by olfactory bulbectomy. Under a light-dark cycle, olfactory bulbectomy significantly modified the expression of daily hypothermia, especially by an increase in the latency to reach minimal daily Tb, suggesting a delayed response to induction of daily hypothermia by light onset. Reentrainment rates following both a 6-h phase advance and a 6-h phase delay of entrained LD were also delayed in bulbectomized males. Olfactory bulbectomy led to significant fragmentation of locomotor activity and increased locomotor activity levels during the resting period. The shortening of circadian periods in bulbectomized males could partly explain the delayed responses to photic stimuli since in control males, the longer the circadian period, the better the response to light entrainment. This experiment shows for the 1st time that olfactory bulbs can markedly modify the circadian system in a primate.

  1. Abrasive water suspension jet -- A multifunctional working tool for underwater applications

    SciTech Connect

    Brandt, C.; Louis, H.; Meier, G.; Tebbing, G.

    1995-12-31

    It is the aim of the paper to show the possibilities of Abrasive Water Suspension Jets (AWSJ) for underwater machining tasks in the offshore industry and other deep sea operations. The AWSJ is a remote-controllable and multifunctional tool for different underwater purposes like maintenance and repair as well as salvage, removal and decommissioning. Therefore it is possible to clean structures from rust and marine growth, to remove concrete and other functional coatings, to cut through different materials as well as composite materials and also to carry out the preparation for repair welding. First the paper will give some basic information about Abrasive Water Jets under water and about the equipment to produce AWSJ. Afterwards the possibilities of jet generation for cutting (round jet), cleaning and material removal (flat jet) and multifunctional operation will be demonstrated. Test results which were carried out under water will be presented. The influence of relevant parameters on processing efficiency is given and discussed.

  2. Gradual training reduces practice difficulty while preserving motor learning of a novel locomotor task.

    PubMed

    Sawers, Andrew; Hahn, Michael E

    2013-08-01

    Motor learning strategies that increase practice difficulty and the size of movement errors are thought to facilitate motor learning. In contrast to this, gradual training minimizes movement errors and reduces practice difficulty by incrementally introducing task requirements, yet remains as effective as sudden training and its large movement errors for learning novel reaching tasks. While attractive as a locomotor rehabilitation strategy, it remains unknown whether the efficacy of gradual training extends to learning locomotor tasks and their unique requirements. The influence of gradual vs. sudden training on learning a locomotor task, asymmetric split belt treadmill walking, was examined by assessing whole body sagittal plane kinematics during 24 hour retention and transfer performance following either gradual or sudden training. Despite less difficult and less specific practice for the gradual cohort on day 1, gradual training resulted in equivalent motor learning of the novel locomotor task as sudden training when assessed by retention and transfer a day later. This suggests that large movement errors and increased practice difficulty may not be necessary for learning novel locomotor tasks. Further, gradual training may present a viable locomotor rehabilitation strategy avoiding large movement errors that could limit or impair improvements in locomotor performance.

  3. Evaluation of the interaction of mu and kappa opioid agonists on locomotor behavior in the horse.

    PubMed Central

    Mama, K R; Pascoe, P J; Steffey, E P

    1993-01-01

    This study was designed to determine the interactive effects of mu and kappa opioid agonists on locomotor behavior in the horse. Three doses of a mu agonist, fentanyl (5, 10, 20 micrograms/kg) and a kappa agonist U50,488H (30, 60, 120 micrograms/kg) were administered in a random order to six horses. Locomotor activity was measured using a two minute footstep count. Each dose of U50,488H was then combined with 20 micrograms/kg of fentanyl to determine the interactive effects of the drugs on locomotor activity. A significant increase in locomotor activity was seen with 20 micrograms/kg of fentanyl and all the drug combinations. The combination of U50,488H with fentanyl resulted in an earlier onset of locomotor activity. At the highest doses of the combination (U50,488H 120 micrograms/kg, fentanyl 20 micrograms/kg), the duration of locomotor activity was significantly increased when compared to the other doses. We conclude that locomotor activity is maintained or enhanced in horses when a receptor specific kappa agonist is combined with a mu receptor agonist. PMID:8490803

  4. Locomotor recovery after spinal cord contusion injury in rats is improved by spontaneous exercise.

    PubMed

    Van Meeteren, Nico L U; Eggers, Ruben; Lankhorst, Alex J; Gispen, Willem Hendrik; Hamers, Frank P T

    2003-10-01

    We have recently shown that enriched environment (EE) housing significantly enhances locomotor recovery following spinal cord contusion injury (SCI) in rats. As the type and intensity of locomotor training with EE housing are rather poorly characterized, we decided to compare the effectiveness of EE housing with that of voluntary wheel running, the latter of which is both well characterized and easily quantified. Female Wistar rats were made familiar with three types of housing conditions, social housing (nine together) in an EE (EHC), individual housing in a running wheel cage (RUN, n = 8), and standard housing two together (CON, n = 10). Subsequently, a 12.5 gcm SCI at Th8 was produced and animals were randomly divided over the three housing conditions. Locomotor function was measured regularly, once a week by means of the BBB score, BBB sub score, TLH test, Gridwalk test, and CatWalk test. In the RUN group, daily distance covered was also measured. Locomotor recovery in the EHC and the RUN groups was equal and significantly better than in the CON group. The extent of recovery at 8 weeks post injury in the RUN group did not correlate with distance covered. We conclude that locomotor training needs to exceed a given threshold in order to be effective in enhancing locomotor recovery in this experimental model, but that once this threshold is exceeded no further improvement occurs, and that the specificity of locomotor training plays little role.

  5. Underwater noise levels in UK waters

    NASA Astrophysics Data System (ADS)

    Merchant, Nathan D.; Brookes, Kate L.; Faulkner, Rebecca C.; Bicknell, Anthony W. J.; Godley, Brendan J.; Witt, Matthew J.

    2016-11-01

    Underwater noise from human activities appears to be rising, with ramifications for acoustically sensitive marine organisms and the functioning of marine ecosystems. Policymakers are beginning to address the risk of ecological impact, but are constrained by a lack of data on current and historic noise levels. Here, we present the first nationally coordinated effort to quantify underwater noise levels, in support of UK policy objectives under the EU Marine Strategy Framework Directive (MSFD). Field measurements were made during 2013–2014 at twelve sites around the UK. Median noise levels ranged from 81.5–95.5 dB re 1 μPa for one-third octave bands from 63–500 Hz. Noise exposure varied considerably, with little anthropogenic influence at the Celtic Sea site, to several North Sea sites with persistent vessel noise. Comparison of acoustic metrics found that the RMS level (conventionally used to represent the mean) was highly skewed by outliers, exceeding the 97th percentile at some frequencies. We conclude that environmental indicators of anthropogenic noise should instead use percentiles, to ensure statistical robustness. Power analysis indicated that at least three decades of continuous monitoring would be required to detect trends of similar magnitude to historic rises in noise levels observed in the Northeast Pacific.

  6. Hydrogel microphones for stealthy underwater listening

    PubMed Central

    Gao, Yang; Song, Jingfeng; Li, Shumin; Elowsky, Christian; Zhou, You; Ducharme, Stephen; Chen, Yong Mei; Zhou, Qin; Tan, Li

    2016-01-01

    Exploring the abundant resources in the ocean requires underwater acoustic detectors with a high-sensitivity reception of low-frequency sound from greater distances and zero reflections. Here we address both challenges by integrating an easily deformable network of metal nanoparticles in a hydrogel matrix for use as a cavity-free microphone. Since metal nanoparticles can be densely implanted as inclusions, and can even be arranged in coherent arrays, this microphone can detect static loads and air breezes from different angles, as well as underwater acoustic signals from 20 Hz to 3 kHz at amplitudes as low as 4 Pa. Unlike dielectric capacitors or cavity-based microphones that respond to stimuli by deforming the device in thickness directions, this hydrogel device responds with a transient modulation of electric double layers, resulting in an extraordinary sensitivity (217 nF kPa−1 or 24 μC N−1 at a bias of 1.0 V) without using any signal amplification tools. PMID:27554792

  7. Underwater loudness for pure tones: Duration effects

    NASA Astrophysics Data System (ADS)

    Cudahy, Edward A.; Schwaller, Derek; Fothergill, David; Wolgemuth, Keith

    2003-04-01

    The loudness of underwater pure tones was measured by loudness matching for pure tones from 100 to 16,000 Hz. The standard was a one second tone at 1000 Hz. The signal duration was varied from 20 milliseconds to 5 seconds. Subjects were instructed to match the loudness of the comparison tone at one of the test frequencies to the loudness of the standard tone. Loudness was measured at the threshold, the most comfortable loudness, and the maximum tolerable loudness. The intensity of the standard was varied randomly across the test series. The subjects were bareheaded U.S. Navy divers tested at a depth of 3 meters. All subjects had normal in-air hearing. Tones were presented to the right side of the subject from an array of underwater sound projectors. The sound pressure level was calibrated at the location of the subject's head with the subject absent. Loudness increased and threshold decreased as duration increased. The effect was greatest at the lowest and highest frequencies. The shape of the loudness contours across frequency and duration derived from these measurements are different from in-air measurements. [Research supported by ONR.

  8. Hydrogel microphones for stealthy underwater listening

    NASA Astrophysics Data System (ADS)

    Gao, Yang; Song, Jingfeng; Li, Shumin; Elowsky, Christian; Zhou, You; Ducharme, Stephen; Chen, Yong Mei; Zhou, Qin; Tan, Li

    2016-08-01

    Exploring the abundant resources in the ocean requires underwater acoustic detectors with a high-sensitivity reception of low-frequency sound from greater distances and zero reflections. Here we address both challenges by integrating an easily deformable network of metal nanoparticles in a hydrogel matrix for use as a cavity-free microphone. Since metal nanoparticles can be densely implanted as inclusions, and can even be arranged in coherent arrays, this microphone can detect static loads and air breezes from different angles, as well as underwater acoustic signals from 20 Hz to 3 kHz at amplitudes as low as 4 Pa. Unlike dielectric capacitors or cavity-based microphones that respond to stimuli by deforming the device in thickness directions, this hydrogel device responds with a transient modulation of electric double layers, resulting in an extraordinary sensitivity (217 nF kPa-1 or 24 μC N-1 at a bias of 1.0 V) without using any signal amplification tools.

  9. Impacts of optical turbulence on underwater imaging

    NASA Astrophysics Data System (ADS)

    Hou, Weilin; Woods, S.; Goode, W.; Jarosz, E.; Weidemann, A.

    2011-06-01

    Optical signal transmission underwater is of vital interests to both civilian and military applications. The range and signal to noise during the transmission, as a function of system and water optical properties determines the effectiveness of EO technology. These applications include diver visibility, search and rescue, mine detection and identification, and optical communications. The impact of optical turbulence on underwater imaging has been postulated and observed by many researchers. However, no quantative studies have been done until recently, in terms of both the environmental conditions, and impacts on image quality as a function of range and spatial frequencies. Image data collected from field measurements during SOTEX (Skaneateles Optical Turbulence Exercise, July 22-31, 2010) using the Image Measurement Assembly for Subsurface Turbulence (IMAST) are presented. Optical properties of the water column in the field were measured using WETLab's ac-9 and Laser In Situ Scattering and Transmissometer (LISST, Sequoia Scientific), in coordination with physical properties including CTD (Seabird), dissipation rate of kinetic energy and heat, using both the Vector velocimeter and CT combo (Nortek and PME), and shear probe based Vertical Microstructure Profiler (VMP, Rockland). The strong stratification structure in the water column provides great opportunity to observe various dissipation strengths throughout the water column, which corresponds directly with image quality as shown. Initial results demonstrate general agreement between data collected and model prediction, while discrepancies between measurements and model suggest higher spatial and temporal observations are needed in the future.

  10. Range Imaging for Underwater Vision Enhancement

    SciTech Connect

    Rish, J.W.; Blume, B.; Nellums, B.; Sackos, J.; Foster, J.; Wood, J.L.

    1999-04-19

    This paper presents results from a series of preliminary tests to evaluate a scannerless range-imaging device as a potential sensory enhancement tool for divers and as a potential identification sensor for deployment on small unmanned underwater vehicles. The device, developed by Sandia National Laboratories, forms an image on the basis of point-to-point range to the target rather than an intensity map. The range image is constructed through a classical continuous wave phase detection technique in which the light source is amplitude modulated at radio frequencies. The receiver incorporates a gain-modulated image intensifier, and range information is calculated on the basis of the phase difference between the transmitted and reflected signal. The initial feasibility test at the Coastal Systems Station showed the device to be effective at imaging low-contrast underwater targets such as concertina wire. It also demonstrated success at imaging a 21-inch sphere at a depth of 10 feet in the water column through a wavy air-water interface.

  11. Underwater noise levels in UK waters.

    PubMed

    Merchant, Nathan D; Brookes, Kate L; Faulkner, Rebecca C; Bicknell, Anthony W J; Godley, Brendan J; Witt, Matthew J

    2016-11-10

    Underwater noise from human activities appears to be rising, with ramifications for acoustically sensitive marine organisms and the functioning of marine ecosystems. Policymakers are beginning to address the risk of ecological impact, but are constrained by a lack of data on current and historic noise levels. Here, we present the first nationally coordinated effort to quantify underwater noise levels, in support of UK policy objectives under the EU Marine Strategy Framework Directive (MSFD). Field measurements were made during 2013-2014 at twelve sites around the UK. Median noise levels ranged from 81.5-95.5 dB re 1 μPa for one-third octave bands from 63-500 Hz. Noise exposure varied considerably, with little anthropogenic influence at the Celtic Sea site, to several North Sea sites with persistent vessel noise. Comparison of acoustic metrics found that the RMS level (conventionally used to represent the mean) was highly skewed by outliers, exceeding the 97(th) percentile at some frequencies. We conclude that environmental indicators of anthropogenic noise should instead use percentiles, to ensure statistical robustness. Power analysis indicated that at least three decades of continuous monitoring would be required to detect trends of similar magnitude to historic rises in noise levels observed in the Northeast Pacific.

  12. Underwater noise levels in UK waters

    PubMed Central

    Merchant, Nathan D.; Brookes, Kate L.; Faulkner, Rebecca C.; Bicknell, Anthony W. J.; Godley, Brendan J.; Witt, Matthew J.

    2016-01-01

    Underwater noise from human activities appears to be rising, with ramifications for acoustically sensitive marine organisms and the functioning of marine ecosystems. Policymakers are beginning to address the risk of ecological impact, but are constrained by a lack of data on current and historic noise levels. Here, we present the first nationally coordinated effort to quantify underwater noise levels, in support of UK policy objectives under the EU Marine Strategy Framework Directive (MSFD). Field measurements were made during 2013–2014 at twelve sites around the UK. Median noise levels ranged from 81.5–95.5 dB re 1 μPa for one-third octave bands from 63–500 Hz. Noise exposure varied considerably, with little anthropogenic influence at the Celtic Sea site, to several North Sea sites with persistent vessel noise. Comparison of acoustic metrics found that the RMS level (conventionally used to represent the mean) was highly skewed by outliers, exceeding the 97th percentile at some frequencies. We conclude that environmental indicators of anthropogenic noise should instead use percentiles, to ensure statistical robustness. Power analysis indicated that at least three decades of continuous monitoring would be required to detect trends of similar magnitude to historic rises in noise levels observed in the Northeast Pacific. PMID:27830837

  13. Underwater manifold marks North Sea first

    SciTech Connect

    Steven, R.R.

    1981-01-01

    In the 12 years since commercial oil was first discovered in the area, the North Sea has been the stimulus for technologic development unrivalled in the history of the petroleum industry. However, technology still has a long way to go before the North Sea can be mastered, insuring that there will be no let-up as long as there is oil to be found. Evidence for this will be provided later this year when Shell UK exploration and production, on behalf of Shell and Esso, installs an Underwater Manifold Center (UMC) in 490 ft of water as part of the $650-million development of the Central Cormorant field, northeast of Shetland. While the East Shetland Basin can no longer be described as frontier territory in terms of environment and water depth, Shell/Esso's UMC is certainly in the frontier class. The manfold center is characterized as a revolution in underwater techniques and an extremely important landmark, not only in North Sea history but in world oil production. The UMC will have future applications in 3 distinct situations. It will be suitable for economically developing satellite fields out of reach of a centrally installed platform. It also will foster exploitation of marginal oil deposits in combination with a floating platform and possible surface storage. However, perhaps the most exciting possibility raised by the UMC is its application in deep-water production.

  14. Image processing of underwater multispectral imagery

    USGS Publications Warehouse

    Zawada, D. G.

    2003-01-01

    Capturing in situ fluorescence images of marine organisms presents many technical challenges. The effects of the medium, as well as the particles and organisms within it, are intermixed with the desired signal. Methods for extracting and preparing the imagery for analysis are discussed in reference to a novel underwater imaging system called the low-light-level underwater multispectral imaging system (LUMIS). The instrument supports both uni- and multispectral collections, each of which is discussed in the context of an experimental application. In unispectral mode, LUMIS was used to investigate the spatial distribution of phytoplankton. A thin sheet of laser light (532 nm) induced chlorophyll fluorescence in the phytoplankton, which was recorded by LUMIS. Inhomogeneities in the light sheet led to the development of a beam-pattern-correction algorithm. Separating individual phytoplankton cells from a weak background fluorescence field required a two-step procedure consisting of edge detection followed by a series of binary morphological operations. In multispectral mode, LUMIS was used to investigate the bio-assay potential of fluorescent pigments in corals. Problems with the commercial optical-splitting device produced nonlinear distortions in the imagery. A tessellation algorithm, including an automated tie-point-selection procedure, was developed to correct the distortions. Only pixels corresponding to coral polyps were of interest for further analysis. Extraction of these pixels was performed by a dynamic global-thresholding algorithm.

  15. Hydrogel microphones for stealthy underwater listening.

    PubMed

    Gao, Yang; Song, Jingfeng; Li, Shumin; Elowsky, Christian; Zhou, You; Ducharme, Stephen; Chen, Yong Mei; Zhou, Qin; Tan, Li

    2016-08-24

    Exploring the abundant resources in the ocean requires underwater acoustic detectors with a high-sensitivity reception of low-frequency sound from greater distances and zero reflections. Here we address both challenges by integrating an easily deformable network of metal nanoparticles in a hydrogel matrix for use as a cavity-free microphone. Since metal nanoparticles can be densely implanted as inclusions, and can even be arranged in coherent arrays, this microphone can detect static loads and air breezes from different angles, as well as underwater acoustic signals from 20 Hz to 3 kHz at amplitudes as low as 4 Pa. Unlike dielectric capacitors or cavity-based microphones that respond to stimuli by deforming the device in thickness directions, this hydrogel device responds with a transient modulation of electric double layers, resulting in an extraordinary sensitivity (217 nF kPa(-1) or 24 μC N(-1) at a bias of 1.0 V) without using any signal amplification tools.

  16. The flip side of perception-action coupling: locomotor experience and the ontogeny of visual-postural coupling.

    PubMed

    Anderson, D I; Campos, J J; Anderson, D E; Thomas, T D; Witherington, D C; Uchiyama, I; Barbu-Roth, M A

    2001-11-01

    The possible role of motor development on psychological function is once again a topic of great theoretical and practical importance. The revival of this issue has stemmed from a different approach to the topic, away from Gesell's interest in the long-term prediction of psychological functions from early motoric assessments, toward an attempt to understand how the acquisition of motor skills orchestrates psychological changes. This paper describes how the acquisition of one motor skill, prone locomotion, has been linked to developmental changes in an infant's ability to regulate posture based on information available in patterns of optic flow. It is argued that the onset of prone locomotion presses the infant to differentiate spatially delimited regions of optic flow to effectively and efficiently control the important subtasks nested within the larger task of locomotion, namely, steering, attending to the surface of support, and maintaining postural control. Following this argument, a research program is described that aims to determine if locomotor experience is causally linked to improvements in the ability to functionalize peripheral optic flow for postural control or whether locomotor experience is merely a maturational forecaster of such improvements. Finally, a hypothesis is put forward that links the emergence of wariness of heights to infants' ability to regulate posture on the basis of peripheral optic flow. The paper's overarching theoretical point is the principle of probabilistic epigenesis, which states that one developmental acquisition produces experiences that bring about a host of new developmental changes in the same and different domains.

  17. Stability of underwater periodic locomotion

    NASA Astrophysics Data System (ADS)

    Jing, Fangxu; Kanso, Eva

    2013-07-01

    Most aquatic vertebrates swim by lateral flapping of their bodies and caudal fins. While much effort has been devoted to understanding the flapping kinematics and its influence on the swimming efficiency, little is known about the stability (or lack of) of periodic swimming. It is believed that stability limits maneuverability and body designs/flapping motions that are adapted for stable swimming are not suitable for high maneuverability and vice versa. In this paper, we consider a simplified model of a planar elliptic body undergoing prescribed periodic heaving and pitching in potential flow. We show that periodic locomotion can be achieved due to the resulting hydrodynamic forces, and its value depends on several parameters including the aspect ratio of the body, the amplitudes and phases of the prescribed flapping.We obtain closedform solutions for the locomotion and efficiency for small flapping amplitudes, and numerical results for finite flapping amplitudes. This efficiency analysis results in optimal parameter values that are in agreement with values reported for some carangiform fish. We then study the stability of the (finite amplitude flapping) periodic locomotion using Floquet theory. We find that stability depends nonlinearly on all parameters. Interesting trends of switching between stable and unstable motions emerge and evolve as we continuously vary the parameter values. This suggests that, for live organisms that control their flapping motion, maneuverability and stability need not be thought of as disjoint properties, rather the organism may manipulate its motion in favor of one or the other depending on the task at hand.

  18. Diurnal changes in the synthesis of the neurosteroid 7alpha-hydroxypregnenolone stimulating locomotor activity in newts.

    PubMed

    Koyama, Teppei; Haraguchi, Shogo; Vaudry, Hubert; Tsutsui, Kazuyoshi

    2009-04-01

    We recently identified 7alpha-hydroxypregnenolone as a novel amphibian neurosteroid stimulating locomotor activity in newts. Because male newts show marked diurnal changes in locomotor activity, we hypothesized that 7alpha-hydroxypregnenolone may be a key factor for the induction of diurnal changes in locomotor activity in male newts. In this study, we found diurnal changes in 7alpha-hydroxypregnenolone synthesis in the brain of male newts, which paralleled locomotor activity. Interestingly, the production of 7alpha-hydroxypregnenolone in the male newt brain increased during the dark phase when locomotor activity of males was high.

  19. Underwater cladding with laser beam and plasma arc welding

    SciTech Connect

    White, R.A.; Fusaro, R.; Jones, M.G.; Solomon, H.D.; Milian-Rodriguez, R.R.

    1997-01-01

    Two welding processes, plasma arc (transferred arc) (PTA) and laser beam, were investigated to apply cladding to austenitic stainless steels and Inconel 600. These processes have long been used to apply cladding layers , but the novel feature being reported here is that these cladding layers were applied underwater, with a water pressure equivalent to 24 m (80 ft). Being able to apply the cladding underwater is very important for many applications, including the construction of off-shore oil platforms and the repair of nuclear reactors. In the latter case, being able to weld underwater eliminates the need for draining the reactor and removing the fuel. Welding underwater in reactors presents numerous challenges, but the ability to weld without having to drain the reactor and remove the fuel provides a huge cost savings. Welding underwater in reactors must be done remotely, but because of the radioactive corrosion products and neutron activation of the steels, remote welding would also be required even if the reactor is drained and the fuel removed. In fact, without the shielding of the water, the remote welding required if the reactor is drained might be even more difficult than that required with underwater welds. Furthermore, as shall be shown, the underwater welds that the authors have made were of high quality and exhibit compressive rather than tensile residual stresses.

  20. Protocols for Image Processing based Underwater Inspection of Infrastructure Elements

    NASA Astrophysics Data System (ADS)

    O'Byrne, Michael; Ghosh, Bidisha; Schoefs, Franck; Pakrashi, Vikram

    2015-07-01

    Image processing can be an important tool for inspecting underwater infrastructure elements like bridge piers and pile wharves. Underwater inspection often relies on visual descriptions of divers who are not necessarily trained in specifics of structural degradation and the information may often be vague, prone to error or open to significant variation of interpretation. Underwater vehicles, on the other hand can be quite expensive to deal with for such inspections. Additionally, there is now significant encouragement globally towards the deployment of more offshore renewable wind turbines and wave devices and the requirement for underwater inspection can be expected to increase significantly in the coming years. While the merit of image processing based assessment of the condition of underwater structures is understood to a certain degree, there is no existing protocol on such image based methods. This paper discusses and describes an image processing protocol for underwater inspection of structures. A stereo imaging image processing method is considered in this regard and protocols are suggested for image storage, imaging, diving, and inspection. A combined underwater imaging protocol is finally presented which can be used for a variety of situations within a range of image scenes and environmental conditions affecting the imaging conditions. An example of detecting marine growth is presented of a structure in Cork Harbour, Ireland.

  1. The influence of underwater turbulence on optical phase measurements

    NASA Astrophysics Data System (ADS)

    Redding, Brandon; Davis, Allen; Kirkendall, Clay; Dandridge, Anthony

    2016-05-01

    Emerging underwater optical imaging and sensing applications rely on phase-sensitive detection to provide added functionality and improved sensitivity. However, underwater turbulence introduces spatio-temporal variations in the refractive index of water which can degrade the performance of these systems. Although the influence of turbulence on traditional, non-interferometric imaging has been investigated, its influence on the optical phase remains poorly understood. Nonetheless, a thorough understanding of the spatio-temporal dynamics of the optical phase of light passing through underwater turbulence are crucial to the design of phase-sensitive imaging and sensing systems. To address this concern, we combined underwater imaging with high speed holography to provide a calibrated characterization of the effects of turbulence on the optical phase. By measuring the modulation transfer function of an underwater imaging system, we were able to calibrate varying levels of optical turbulence intensity using the Simple Underwater Imaging Model (SUIM). We then used high speed holography to measure the temporal dynamics of the optical phase of light passing through varying levels of turbulence. Using this method, we measured the variance in the amplitude and phase of the beam, the temporal correlation of the optical phase, and recorded the turbulence induced phase noise as a function of frequency. By bench marking the effects of varying levels of turbulence on the optical phase, this work provides a basis to evaluate the real-world potential of emerging underwater interferometric sensing modalities.

  2. Study on Underwater Image Denoising Algorithm Based on Wavelet Transform

    NASA Astrophysics Data System (ADS)

    Jian, Sun; Wen, Wang

    2017-02-01

    This paper analyzes the application of MATLAB in underwater image processing, the transmission characteristics of the underwater laser light signal and the kinds of underwater noise has been described, the common noise suppression algorithm: Wiener filter, median filter, average filter algorithm is brought out. Then the advantages and disadvantages of each algorithm in image sharpness and edge protection areas have been compared. A hybrid filter algorithm based on wavelet transform has been proposed which can be used for Color Image Denoising. At last the PSNR and NMSE of each algorithm has been given out, which compares the ability to de-noising

  3. Specs add confidence in use of wet welding. [Underwater welding

    SciTech Connect

    Not Available

    1984-02-01

    Underwater wet welding can now be utilized with the same confidence as dry welding, provided certain guidelines are followed. A new electrode is discussed that has been delivering exceptionally high quality welds by a diving firm in Houston. With the issuance of the American Welding Society's specifications (ANS/LAWS D3.6-83) much of the confusion surrounding underwater welding should be eliminated. The new specifications establish the levels of quality for underwater welding and gives everyone in the business a common language.

  4. Effects of Underwater Turbine Noise on Crab Larval Metamorphosis.

    PubMed

    Pine, Matthew K; Jeffs, Andrew G; Radford, Craig A

    2016-01-01

    The development of marine tidal turbines has advanced at a rapid rate over the last decade but with little detailed understanding of the potential noise impacts on invertebrates. Previous research has shown that underwater reef noise plays an important role in mediating metamorphosis in many larval crabs and fishes. New research suggests that underwater estuarine noise may also mediate metamorphosis in estuarine crab larvae and that the noise emitted from underwater tidal and sea-based wind turbines may significantly influence larval metamorphosis in estuarine crabs.

  5. Exploring underwater target detection by imaging polarimetry and correlation techniques.

    PubMed

    Dubreuil, M; Delrot, P; Leonard, I; Alfalou, A; Brosseau, C; Dogariu, A

    2013-02-10

    Underwater target detection is investigated by combining active polarization imaging and optical correlation-based approaches. Experiments were conducted in a glass tank filled with tap water with diluted milk or seawater and containing targets of arbitrary polarimetric responses. We found that target estimation obtained by imaging with two orthogonal polarization states always improves detection performances when correlation is used as detection criterion. This experimental study illustrates the potential of polarization imaging for underwater target detection and opens interesting perspectives for the development of underwater imaging systems.

  6. Underwater wet welding (a state of the art report)

    SciTech Connect

    Grubbs, C.E.

    1993-12-31

    This practical report discusses recent advancements in shielded metal arc underwater wet welding technology including wet welds made with ferritic, stainless steel and nickel welding electrodes that meet the requirement of welds made above water. Also discussed is a unique multiple temper bead welding technique that prevents hydrogen induced cracking in the heat affected zones (HAZ) of crack susceptible high strength steels and produces wet weldments with acceptable levels of HAZ hardness and notch toughness. The report recognizes current underwater developmental programs and describes underwater wet welded repairs made on offshore structures, harbor facilities and nuclear power plants and reports their fitness for purpose after ten to twenty years of service.

  7. A Secure Communication Suite for Underwater Acoustic Sensor Networks

    PubMed Central

    Dini, Gianluca; Duca, Angelica Lo

    2012-01-01

    In this paper we describe a security suite for Underwater Acoustic Sensor Networks comprising both fixed and mobile nodes. The security suite is composed of a secure routing protocol and a set of cryptographic primitives aimed at protecting the confidentiality and the integrity of underwater communication while taking into account the unique characteristics and constraints of the acoustic channel. By means of experiments and simulations based on real data, we show that the suite is suitable for an underwater networking environment as it introduces limited, and sometimes negligible, communication and power consumption overhead. PMID:23202204

  8. Demonstration of advanced underwater sensors for military and civilian applications

    NASA Astrophysics Data System (ADS)

    Rankin, Walter; Cooper, Michael T.; Wood-Putnam, Jody L.; Lathrop, John D.

    1999-08-01

    Many operations undertaken by the Defense Department must cope with the active or residual effects of a variety of methods of warfare that a defender can use to inhibit maritime use of the oceans. Prominent cases encountered by the naval forces are mien warfare, salvage and recovery operations, and debris clearance. The office of Naval Research has sponsored development of a family of underwater object location sensors which have a strongly enhanced capability to detect, classify, and identify underwater objects of interest. Use of these sensors in a military exercise, in an operation to locate debris from the Swissair crash, and in a test to demonstrate technology for underwater debris location is described.

  9. WODA Technical Guidance on Underwater Sound from Dredging.

    PubMed

    Thomsen, Frank; Borsani, Fabrizio; Clarke, Douglas; de Jong, Christ; de Wit, Pim; Goethals, Fredrik; Holtkamp, Martine; Martin, Elena San; Spadaro, Philip; van Raalte, Gerard; Victor, George Yesu Vedha; Jensen, Anders

    2016-01-01

    The World Organization of Dredging Associations (WODA) has identified underwater sound as an environmental issue that needs further consideration. A WODA Expert Group on Underwater Sound (WEGUS) prepared a guidance paper in 2013 on dredging sound, including a summary of potential impacts on aquatic biota and advice on underwater sound monitoring procedures. The paper follows a risk-based approach and provides guidance for standardization of acoustic terminology and methods for data collection and analysis. Furthermore, the literature on dredging-related sounds and the effects of dredging sounds on marine life is surveyed and guidance on the management of dredging-related sound risks is provided.

  10. Algorithms and analysis for underwater vehicle plume tracing.

    SciTech Connect

    Byrne, Raymond Harry; Savage, Elizabeth L.; Hurtado, John Edward; Eskridge, Steven E.

    2003-07-01

    The goal of this research was to develop and demonstrate cooperative 3-D plume tracing algorithms for miniature autonomous underwater vehicles. Applications for this technology include Lost Asset and Survivor Location Systems (L-SALS) and Ship-in-Port Patrol and Protection (SP3). This research was a joint effort that included Nekton Research, LLC, Sandia National Laboratories, and Texas A&M University. Nekton Research developed the miniature autonomous underwater vehicles while Sandia and Texas A&M developed the 3-D plume tracing algorithms. This report describes the plume tracing algorithm and presents test results from successful underwater testing with pseudo-plume sources.

  11. Melatonin treatment during the incubation of sensitization attenuates methamphetamine-induced locomotor sensitization and MeCP2 expression.

    PubMed

    Wu, Jintao; Zhu, Dexiao; Zhang, Jing; Li, Guibao; Liu, Zengxun; Sun, Jinhao

    2016-02-04

    Behavior sensitization is a long-lasting enhancement of locomotor activity after exposure to psychostimulants. Incubation of sensitization is a phenomenon of remarkable augmentation of locomotor response after withdrawal and reflects certain aspects of compulsive drug craving. However, the mechanisms underlying these phenomena remain elusive. Here we pay special attention to the incubation of sensitization and suppose that the intervention of this procedure will finally decrease the expression of sensitization. Melatonin is an endogenous hormone secreted mainly by the pineal gland. It is effective in treating sleep disorder, which turns out to be one of the major withdrawal symptoms of methamphetamine (MA) addiction. Furthermore, melatonin can also protect neuronal cells against MA-induced neurotoxicity. In the present experiment, we treated mice with low dose (10mg/kg) of melatonin for 14 consecutive days during the incubation of sensitization. We found that melatonin significantly attenuated the expression of sensitization. In contrast, the vehicle treated mice showed prominent enhancement of locomotor activity after incubation. MeCP2 expression was also elevated in the vehicle treated mice and melatonin attenuated its expression. Surprisingly, correlation analysis suggested significant correlation between MeCP2 expression in the nucleus accumbens (NAc) and locomotion in both saline control and vehicle treated mice, but not in melatonin treated ones. MA also induced MeCP2 over-expression in PC12 cells. However, melatonin failed to reduce MeCP2 expression in vitro. Our results suggest that melatonin treatment during the incubation of sensitization attenuates MA-induced expression of sensitization and decreases MeCP2 expression in vivo.

  12. Electrophysiological characterization of V2a interneurons and their locomotor-related activity in the neonatal mouse spinal cord.

    PubMed

    Zhong, Guisheng; Droho, Steven; Crone, Steven A; Dietz, Shelby; Kwan, Alex C; Webb, Watt W; Sharma, Kamal; Harris-Warrick, Ronald M

    2010-01-06

    The V2a class of Chx10-expressing interneurons has been implicated in frequency-dependent control of left-right phase during locomotion in the mouse. We have used the Chx10::CFP mouse line to further investigate the properties and locomotion-related activity of V2a interneurons in the isolated neonatal spinal cord. V2a interneurons can be divided into three classes, based on their tonic, phasic, or delayed-onset responses to step depolarization. Electrical coupling is found only between neurons of same class and helps to synchronize neuronal activity within the class. Serotonin (5-HT) excites isolated tonic V2a interneurons by depolarizing the neurons and increasing their membrane input resistance, with no significant effects on action potential properties, a mechanism distinct from 5-HT excitation of commissural interneurons. During NMDA-/5-HT-induced locomotor-like activity, patch-clamp recordings and two-photon calcium imaging experiments show that approximately half of V2a interneurons fire rhythmically with ventral root-recorded motor activity; the rhythmic V2a interneurons fired during one half of the cycle, in phase with either the ipsilateral or the contralateral L2 ventral root bursts. The percentage of rhythmically firing V2a interneurons increases during higher-frequency fictive locomotion, and they become significantly more rhythmic in their firing during the locomotor cycle; this may help to explain the frequency-dependent shift in left-right coupling in Chx10::DTA mice, which lack these neurons. Our results together with data from the accompanying paper (Dougherty and Kiehn, 2009) reinforce earlier proposals that the V2a interneurons are components of the hindlimb central pattern generator, helping to organize left-right locomotor coordination in the neonatal mouse spinal cord.

  13. Chronic nicotine differentially alters cocaine-induced locomotor activity in adolescent vs. adult male and female rats.

    PubMed

    Collins, Stephanie L; Izenwasser, Sari

    2004-03-01

    Tobacco use is prevalent in the adolescent population. It is a major concern because tobacco is highly addictive and has also been linked to illicit drug use. There is not much research, however, on the interaction between nicotine and other stimulant drugs in animal models of early adolescence. This study examined the effects of chronic nicotine alone and on cocaine-stimulated activity in male and female periadolescent rats compared to male and female adult rats. During the seven-day nicotine pretreatment period, nicotine increased locomotor activity in all groups compared to vehicle controls. Male and female adult rats and female periadolescent rats developed sensitization to the locomotor-activating effects of nicotine over the 7-day treatment period, while male periadolescent rats did not. All groups treated with nicotine, however, exhibited sensitization to nicotine-induced repetitive motion over the 7-day nicotine treatment period. On day 8, male periadolescent rats pretreated with nicotine were more markedly sensitized to the locomotor-activating effects of cocaine than male adult rats, while female rats pretreated with nicotine were not sensitized to cocaine. In contrast, male and female periadolescent rats, but not adult rats, had increased amounts of repetitive beam breaks induced by cocaine after nicotine pretreatment. Overall, it appears that cross-sensitization to cocaine is greater in periadolescent than in adult rats, and that males are more sensitized than females. Thus, it may be that nicotine use during adolescence carries a greater risk than during adulthood and that male adolescents may be particularly vulnerable to the risk of cocaine abuse after nicotine use. This information should be taken into account so as to help us better understand the development of drug addiction in adolescents compared to adults.

  14. Locomotor adaptation and aftereffects in patients with reduced somatosensory input due to peripheral neuropathy.

    PubMed

    Bunday, Karen L; Bronstein, Adolfo M

    2009-12-01

    We studied 12 peripheral neuropathy patients (PNP) and 13 age-matched controls with the "broken escalator" paradigm to see how somatosensory loss affects gait adaptation and the release and recovery ("braking") of the forward trunk overshoot observed during this locomotor aftereffect. Trunk displacement, foot contact signals, and leg electromyograms (EMGs) were recorded while subjects walked onto a stationary sled (BEFORE trials), onto the moving sled (MOVING or adaptation trials), and again onto the stationary sled (AFTER trials). PNP were unsteady during the MOVING trials, but this progressively improved, indicating some adaptation. During the after trials, 77% of control subjects displayed a trunk overshoot aftereffect but over half of the PNP (58%) did not. The PNP without a trunk aftereffect adapted to the MOVING trials by increasing distance traveled; subsequently this was expressed as increased distance traveled during the aftereffect rather than as a trunk overshoot. This clear separation in consequent aftereffects was not seen in the normal controls suggesting that, as a result of somatosensory loss, some PNP use distinctive strategies to negotiate the moving sled, in turn resulting in a distinct aftereffects. In addition, PNP displayed earlier than normal anticipatory leg EMG activity during the first after trial. Although proprioceptive inputs are not critical for the emergence or termination of the aftereffect, somatosensory loss induces profound changes in motor adaptation and anticipation. Our study has found individual differences in adaptive motor performance, indicative that PNP adopt different feed-forward gait compensatory strategies in response to peripheral sensory loss.

  15. Locomotor Dysfunction after Long-Duration Space Flight and Development of Countermeasures to Facilitate Faster Recovery

    NASA Technical Reports Server (NTRS)

    Mulavara, A. P.; Wood, S. J.; Cohen, H. S.; Bloomberg, J. J.

    2012-01-01

    Exposure to the microgravity conditions of space flight induces adaptive modification in sensorimotor function allowing astronauts to operate in this unique environment. This adaptive state, however, is inappropriate for a 1-g environment. Consequently astronauts must spend time readapting to Earth s gravity following their return to Earth. During this readaptation period, alterations in sensorimotor function cause various disturbances in astronaut gait during postflight walking. They often rely more on vision for postural and gait stability and many report the need for greater cognitive supervision of motor actions that previous to space flight were fully automated. Over the last several years our laboratory has investigated postflight astronaut locomotion with the aim of better understanding how adaptive changes in underlying sensorimotor mechanisms contribute to postflight gait dysfunction. Exposure to the microgravity conditions of space flight induces adaptive modification in the control of vestibularly-mediated reflexive head movement during locomotion after space flight. Furthermore, during motor learning, adaptive transitions are composed of two main mechanisms: strategic and plastic. Strategic mechanisms represent immediate and transitory modifications in control to deal with changes in the prevailing environment that, if prolonged, induce plastic mechanisms designed to automate new behavioral responses. The goal of the present study was to examine the contributions of sensorimotor subsystems such as the vestibular and body load sensing (BLS) somatosensory influences on head movement control during locomotion after long-duration space flight. Further we present data on the two motor learning processes during readaptation of locomotor function after long-duration space flight.

  16. Association of environmental enrichment and locomotor stimulation in a rodent model of cerebral palsy: Insights of biological mechanisms.

    PubMed

    Meireles, André L F; Marques, Marília R; Segabinazi, Ethiane; Spindler, Christiano; Piazza, Francele V; Salvalaggio, Gabriela S; Augustin, Otávio A; Achaval, Matilde; Marcuzzo, Simone

    2017-01-01

    Several physiotherapy approaches are used with different aims in the treatment of cerebral palsy (CP), such as the early stimulation and the locomotor training, but their biological effects, isolated or combined, are not completely known. In animals models, these strategies can be compared, with due translational restrictions, to the environmental enrichment (EE), that involves the enhancement of animal's physical and social environment, and locomotor stimulation (LS), that can be performed using the treadmill adapted for rats. This study was designed to describe which biological and functional mechanisms underlying rehabilitative process in clinical practice. Male rat pups were initially divided in two groups: control (healthy) and submitted to a CP model. Then, pups were divided in eight groups: CP, CPEE, CPLS, CPEELS and its respectively control groups. Functional outcomes were assessed at the postnatal day (P) 31 and P52. The tibialis anterior and soleus muscles, tibia bone parameters, the expression of synaptophysin in the primary motor cortex (M1) and ventral horn (VH) of the spinal cord, were evaluated. The association of therapies was able to improve the functional assessments and musculoskeletal parameters. Isolated therapies presented complementary benefits in CP, but the association of therapies proved to be a fundamental and effective strategy to functional recovery, besides alter positively all biological tissues evaluated in this study.

  17. Effect of aestivation on muscle characteristics and locomotor performance in the green-striped burrowing frog, Cyclorana alboguttata.

    PubMed

    Hudson, N J; Franklin, C E

    2002-02-01

    The Green-striped burrowing frog, Cyclorana alboguttata survives extended drought periods by burrowing underground and aestivating. These frogs remain immobile within cocoons of shed skin and mucus during aestivation and emerge from their burrows upon heavy rains to feed and reproduce. Extended periods of immobilisation in mammals typically result in muscle atrophy and a decrease in muscle performance. We examined the effect of aestivation and hence prolonged immobilisation, on skeletal muscle mass, in vitro muscle performance, and locomotor performance in C. alboguttata. Frogs were aestivated in soil for 3 months and were compared with control animals that remained active, were fed, and had a continual supply of water. Compared to the controls, the wet mass of the gastrocnemius, sartorius, gracilus major, semimembranosus, peroneus, extensor cruris, tibialis posticus and tibialis anticus longus of aestivators remained unchanged indicating no muscle atrophy. The in-vitro performance characteristics of the gastrocnemius muscle were maintained and burst swimming speed was unaffected, requiring no recovery from the extended period of immobilisation associated with aestivation. This preservation of muscle size, contractile condition and locomotor performance through aestivation enables C. alboguttata to compress their life history into unpredictable windows of opportunity, whenever heavy rains occur.

  18. The comparative effects of chronic consumption of kola nut (Cola nitida) and caffeine diets on locomotor behaviour and body weights in mice.

    PubMed

    Umoren, E B; Osim, E E; Udoh, P B

    2009-06-01

    The comparative effects of chronic [28 days] consumption of kola nut and its active constituent, caffeine diets on locomotor behaviour and body weights in mice were investigated. Thirty adult Swiss white mice [15-30 g body weight], were used for the study. The open field-maze was employed for the evaluation of locomotor behaviour. Mice in the control group [n=10] were fed normal rodent chow, mice in the kola nut-fed group [n=10] were fed kola diet [25 % wt/wt of rodent chow] while those in the caffeine-fed group [n=10] were fed caffeine diet [0.66% wt/wt of rodent chow] for 4 weeks. All animals were allowed free access to clean drinking water. Daily food intake, water intake and body weight change were also measured. Daily food intake in the kola nut and caffeine-fed group of mice was significantly [P<0.001 respectively] lower than the control. There was also a significant [P<0.001] decrease in daily water intake in the caffeine-fed group compared to the control whereas, the apparent decrease of water intake in the kola nut-fed group was not significantly different from the control. Body weight change was also significantly [P<0.001 and P<0.05 respectively] lower in the kola nut and caffeine-fed groups of mice when compared to the control. The frequency of rearing in the open field was significantly [P<0.01] lower in the caffeine-fed group of mice when compared to the control. The frequency of grooming was also significantly [P<0.05] lower in the caffeine-fed group of mice when compared to the control. There was also a significant [P<0.05] decrease in the frequency of light-dark transitions in the light/dark transition box for the caffeine-fed group when compared to the control. The results showed that chronic consumption of kola nut and caffeine diets caused decrease in food intake and body weight. Consumption of caffeine-diet also significantly decreased water intake and locomotor activity. The effect of kola nut-diets on water intake and locomotor activity was

  19. Ultrasonic Transducers for Air and Underwater Communication.

    NASA Astrophysics Data System (ADS)

    Koosha, Abdolrahim

    Available from UMI in association with The British Library. The performance of a novel radiator capable of producing ultrasonic waves in air and liquids has been investigated. For commercial transducers when operating in air or liquids, impedance matching is the necessary condition for maximum transfer of energy to the medium (thus no standing waves are involved). However, for this radiator the formation of the mechanical standing waves on it is the key condition for directional radiation of energy into the surrounding environment. Under this condition the radiator exhibits a practical conversion of electrical energy into ultrasound. To further improve the performance of the radiator the wavelength coincidence condition must be satisfied. This condition implies that the wavelength of the bending vibration developed on the blade to be the same as that in the medium to which it is coupled. Consequently, an end-fire radiation pattern is obtained. The theory of this when applied to water and also for a double blade configuration are presented. The main component of the radiator consists of a cantilever blade on which a pair of piezoelectric (PZT) ceramic bars are fixed. These the so called excitation gauges, are fixed on both sides of a thin rectangular metal blade near the clamped end. When wavelength coincidence condition is fulfilled, the radiator transmits ultrasonic wave in a highly directional pattern. The direction of propagation of ultrasound is solely steered by frequency of the applied signal. System imperfections such as inter modal coupling when used underwater are considered. An analytical approach is developed to investigate the performance of the radiator for transmission of digital signals in air as well as in water. This method is used to evaluate the efficiency of the device as a suitable means for communication between divers or a diver and an underwater stationary station. Amplitude modulation of speech signals demonstrated the capabilities of a new

  20. Transplantation of mature adipocyte-derived dedifferentiated fat cells promotes locomotor functional recovery by remyelination and glial scar reduction after spinal cord injury in mice.

    PubMed

    Yamada, Hiromi; Ito, Daisuke; Oki, Yoshinao; Kitagawa, Masato; Matsumoto, Taro; Watari, Tosihiro; Kano, Koichiro

    2014-11-14

    Mature adipocyte-derived dedifferentiated fat cells (DFAT) have a potential to be useful as new cell-source for cell-based therapy for spinal cord injury (SCI), but the mechanisms remain unclear. The objective of this study was to examine whether DFAT-induced functional recovery is achieved through remyelination and/or glial scar reduction in a mice model of SCI. To accomplish this we subjected adult female mice (n=22) to SCI. On the 8th day post-injury locomotor tests were performed, and the mice were randomly divided into two groups (control and DFAT). The DFAT group received stereotaxic injection of DFAT, while the controls received DMEM medium. Functional tests were conducted at repeated intervals, until the 36th day, and immunohistochemistry or staining was performed on the spinal cord sections. DFAT transplantation significantly improved locomotor function of their hindlimbs, and promoted remyelination and glial scar reduction, when compared to the controls. There were significant and positive correlations between promotion of remyelination or/and reduction of glial scar, and recovery of locomotor function. Furthermore, transplanted DFAT expressed markers for neuron, astrocyte, and oligodendrocyte, along with neurotrophic factors, within the injured spinal cord. In conclusion, DFAT-induced functional recovery in mice after SCI is probably mediated by both cell-autonomous and cell-non-autonomous effects on remyelination of the injured spinal cord.