Kinematics of forward and backward locomotion performed in different environmental conditions

Mice are frequently used in analyses of the locomotor system. Although forward locomotion (FWL) in intact mice has been studied previously, backward locomotion (BWL) in mice has never been analyzed. The aim of the present study was to compare kinematics of FWL and BWL performed in different environmental conditions (i.e., in a tunnel, on a treadmill, and on an air-ball). In all setups, the average speed and step amplitude during BWL were significantly reduced compared with FWL. The cycle duration varied greatly during both FWL and BWL. The average swing duration during BWL was twice shorter than during FWL on each setup. Mice exhibited different interlimb coordinations (trot and walk with lateral or diagonal sequence) during BWL but only one gait (walk with lateral sequence) during FWL. Location of the rostro-caudal paw trajectory in relation to the hip projection to the surface (HP) depended on hip height. With low hip height, the trajectory was displaced either rostrally (anterior steps) or caudally (posterior steps) to HP. With high hip height, HP was near the middle of the trajectory (middle steps). During FWL, all three forms of steps were observed in the tunnel and predominantly anterior and posterior steps on the treadmill and air-ball, respectively. During BWL, only anterior steps were observed. Intralimb coordination depended on the form of stepping. Limb joints were coordinated to keep the hip at approximately constant height during stance and to have the smallest functional limb length during swing when the limb passed under the hip. NEW & NOTEWORTHY Mice are extensively used for the analysis of the locomotor system. This study is the first examination of the kinematics of forward and backward locomotor movements in different environmental conditions in mice. Obtained results represent a benchmark for studies based on manipulations of activity of specific populations of neurons to reveal their roles in control of specific aspects of locomotion.

Research on the Dynamic Calibration of Thermocouple and Temperature Excitation Signal Generation Method Based on Shock-Tube Theory

This paper introduces the equipment for generating an excitation signal during the process of thermocouple dynamic calibration in air medium, with the objective of dealing with the problems existing extensively in the excitation signal of incapable assessment of the rising time and inaccuracy in the traceability for the step amplitude. Based on the shock-tube theory, the step-temperature excitation signal that is suitable for the dynamic calibration of the thermocouple with appreciable rising time, wide-frequency bandwidth, and traceable step amplitude can be generated by means of the improvement in the structure of the traditional shock tube as well as the compensation of the shock-tube parameters. Through on-site assessment experimentation and dynamic modeling of the thermocouple, the time constant of the thermocouple can be obtained and the dynamic response of the thermocouple can be modified and compensated, the calibration result of which shows that the dynamic calibration method of the thermocouple proposed in this paper can be implemented for different ranges of frequencies and different phases of the temperature sensor with high reliability; moreover, the calibration equipment is miniaturized.

Study on Transient Temperature Generator and Dynamic Compensation Technology

According to the problem of dynamic calibration of the thermocouple, especially impossible to evaluate the rise time and to unify the calibration method, a new method of thermocouple calibration is proposed. Based on the method rise time of the input signal of thermocouple and step amplitude could evaluate accurately. The practical process of calibration shows that the method is effective.

High-Speed Bonding of Resin-Coated Cu Wire and Sn Electrode with Ultrasonic Bonding for High-Frequency Chip Coil

High-speed ultrasonic bonding method has been developed to join resin-coated Cu wire on Sn electrodes for high-frequency chip coils. Two-step amplitude method, which decreases the ultrasonic amplitude in the bonding process, was effective to join the resin-coated Cu wire on Sn electrodes. The surface roughness treatment for a bonder head accelerated the deformation of the wire in the bonding process and improve the bondability compared to using the bonder head without that treatment. This paper also describes bonding properties of the joint and the bonding mechanism.

The relationship between leg stepping pattern and yaw torque oscillations in curve walking of two crayfish species

Curve walking in two species of crayfish, Procambarus clarkii and Astacus leptodactylus, was investigated to test whether the mechanism underlying curve walking is the synchronous action of a centrally pre-programmed leg tripod or whether it is the action of one principal leg that produces the main body yaw torque. Curve walking was induced by an optomotor visual stimulus, and the yaw torque produced by the tethered animals was measured in open-loop conditions. Our main results suggest that the yaw torque oscillations in both P. clarkii and A. leptodactylus are related to the movement of outer leg 4 (i.e. leg 4 on the outside of the turn). That is, the peaks in the yaw torque occur, on average, in synchrony with the power stroke of outer leg 4. When comparing the results of this open-loop experiment on P. clarkii with results previously obtained for curve walking in untethered individuals of the same species, we found a much higher variability in leg coordination in the open-loop situation. Similarly, here we did not find the same level of synchrony in the tripod (formed by outer leg 4 and inner legs 2 and 5) observed during untethered free walking. Therefore, we suggest that tethered conditions may diminish the need for stability and thus allow outer leg 4 to produce a body rotation regardless of the leg stepping configuration. The characteristics of leg 4 are in line with its major role in turning. According to previous studies, legs 4 provide the largest force and the largest step amplitude during walking, and their force includes both a pulling and a pushing component which can facilitate the control of turning. Although it is apparent that outer leg 4 is not the only leg that can produce an inward yaw torque, its major role in modulating the yaw torque suggests that there may be a specific, centrally generated control of outer leg 4 during curve walking in crayfish.

Grasp Stiffness as a Function of Grasp Force and Finger Span

The purpose of this study was to determine whether direct measurements of grasp stiffness agreed with stiffness inferred from the slopes of isovolitional force-span characteristics derived from previous grasp-effort matching data. Grasp stiffness for three-finger pinch was measured as a function of initial force and finger span using step displacements applied in a do-not-intervene paradigm. Subjects pinched a free-floating, motorized manipulandum in each hand and squeezed both with equal effort; one of the hands was perturbed at random. Stiffness was calculated from the initial and final steady-state values of force and span. The effects of step amplitude, rise-time, and initial load stiffness were investigated; grasp stiffness decreased significantly for larger steps, increased slightly for longer rise-times, and was unaffected by load stiffness. Grasp stiffness then was measured as a function of initial force and span using a single set of step parameters. Stiffness increased significantly in proportion to force but was changed only slightly by span. It was concluded that the perturbation and effort-matching measures of stiffness are not equivalent and represent different components of motor behavior.