507 research outputs found

    The role of IL-4 and Th2-like cytokines in pulmonary tuberculosis

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    Includes bibliographical referencesTuberculosis (TB) vaccine candidates have been mostly ineffective and it remains unclear as to what constitutes protective host immunity. Despite high levels of IFN-γ at the site of disease, the Th1 cytokine associated with protection, many individuals still have progressive active TB. Whether a Th2-like immune response (IL-4; IL-4δ2; IL-9) can subvert protective host immunity requires clarification

    Analysis of a closed-kinematic chain robot manipulator

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    Presented are the research results from the research grant entitled: Active Control of Robot Manipulators, sponsored by the Goddard Space Flight Center (NASA) under grant number NAG-780. This report considers a class of robot manipulators based on the closed-kinematic chain mechanism (CKCM). This type of robot manipulators mainly consists of two platforms, one is stationary and the other moving, and they are coupled together through a number of in-parallel actuators. Using spatial geometry and homogeneous transformation, a closed-form solution is derived for the inverse kinematic problem of the six-degree-of-freedom manipulator, built to study robotic assembly in space. Iterative Newton Raphson method is employed to solve the forward kinematic problem. Finally, the equations of motion of the above manipulators are obtained by employing the Lagrangian method. Study of the manipulator dynamics is performed using computer simulation whose results show that the robot actuating forces are strongly dependent on the mass and centroid locations of the robot links

    Cartesian path control of a two-degree-of-freedom robot manipulator

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    The problem of cartesian trajectory control of a closed-kinematic chain mechanism robot manipulator with possible space station applications is considered. The study was performed by both computer simulation and experimentation for tracking of three different paths: a straight line, a sinusoid and a circle. Linearization and pole placement methods are employed to design controller gains. Results show that the controllers are robust and there are good agreements between simulation and experimentation. Excellent tracking quality and small overshoots are also evident

    Development of kinematic equations and determination of workspace of a 6 DOF end-effector with closed-kinematic chain mechanism

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    This report presents results from the research grant entitled Active Control of Robot Manipulators, funded by the Goddard Space Flight Center, under Grant NAG5-780, for the period July 1, 1988 to January 1, 1989. An analysis is presented of a 6 degree-of-freedom robot end-effector built to study telerobotic assembly of NASA hardware in space. Since the end-effector is required to perform high precision motion in a limited workspace, closed-kinematic mechanisms are chosen for its design. A closed-form solution is obtained for the inverse kinematic problem and an iterative procedure employing Newton-Raphson method is proposed to solve the forward kinematic problem. A study of the end-effector workspace results in a general procedure for the workspace determination based on link constraints. Computer simulation results are presented

    Genetic aspects of yield, feed intake and feed efficiency in dairy cattle fed Ad Libitum

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    Combining ability and heterosis for grain yield, fodder yield and other agronomic traits in sorghum [Sorghum bicolor (L.) Moench]

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    Forty five hybrids derived from a diallel mating design of ten parents and one standard check PUSA CHARI-121 were evaluated for general and specific combining ability effects and standard heterosis for grain yield/plant, dry fodder yield/plant, days to 50 per cent flowering, plant height, number of leaves/plant, leaf length, leaf breadth and 100- seed weight of Sorghum bicolor. The mean square due to general and specific combining ability was significan for Days to 50% flowering, Days to maturity, Plant height (cm),No of Leaves/plant, Leaf length (cm), Leaf width (cm), seed yield/plant (g), Fodder yield/plant (q/ha) and 100-seed weight (g) for all the characters. Both additive and non additive genetic effects were present in the material under study. However the ratio of ?2gca/ ?2sca suggested that the preponderance of non additive gene action in expression of all the characters under study. Out of the nine parents PUSA CHARI-121, PANT CHARI-4, MP CHARI, PANT CHARI-6 and PANT CHARI-5 identified as good general combiner for grain yield/plant, dry fodder yield/plant and other agronomical traits. The hybrid HC-136 x PANT CHARI-4 and PANT CHARI-4 x PUSA CHARI-121 for grain yield/plant and hybrid MP CHARI x PANT CHARI-6, PANT CHARI-5 x SPV 1616 and HC-136 x PANT CHARI-4 for dry fodder yield/plant exhibited higher magnitude of positive significant specific combining ability effect with highest standard heterosis and per se performance. These hybrids were also found suitable for two or three yield contributing traits. In general, close association between specific combining ability effects and standard heterosis was observed among the best hybrids identified on the basis of specific combining ability effects for grain and dry fodder yield

    Trajectory control of robot manipulators with closed-kinematic chain mechanism

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    The problem of Cartesian trajectory control of a closed-kinematic chain mechanism robot manipulator, recently built at CAIR to study the assembly of NASA hardware for the future Space Station, is considered. The study is performed by both computer simulation and experimentation for tracking of three different paths: a straight line, a sinusoid, and a circle. Linearization and pole placement methods are employed to design controller gains. Results show that the controllers are robust and there are good agreements between simulation and experimentation. The results also show excellent tracking quality and small overshoots

    The protection of the marine environment within the territorial seas and contiguous zone of India as part of salvage interventions

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