Clemson University

About: Clemson University is a education organization based out in Clemson, South Carolina, United States. It is known for research contribution in the topics: Population & Control theory. The organization has 20556 authors who have published 42518 publications receiving 1170779 citations. The organization is also known as: Clemson Agricultural College of South Carolina.

Mechanism and regulation of Mg-chelatase

Abstract: Mg-chelatase catalyses the insertion of Mg into protoporphyrin IX (Proto). This seemingly simple reaction also is potentially one of the most interesting and crucial steps in the (bacterio)chlorophyll (Bchl/Chl)-synthesis pathway, owing to its position at the branch-point between haem and Bchl/Chl synthesis. Up until the level of Proto, haem and Bchl/Chl synthesis share a common pathway. However, at the point of metal-ion insertion there are two choices: Mg2+ insertion to make Bchl/Chl (catalysed by Mg-chelatase) or Fe2+ insertion to make haem (catalysed by ferrochelatase). Thus the relative activities of Mg-chelatase and ferrochelatase must be regulated with respect to the organism's requirements for these end products. How is this regulation achieved? For Mg-chelatase, the recent design of an in vitro assay combined with the identification of Bchl-biosynthetic enzyme genes has now made it possible to address this question. In all photosynthetic organisms studied to date, Mg-chelatase is a three-component enzyme, and in several species these proteins have been cloned and expressed in an active form. The reaction takes place in two steps, with an ATP-dependent activation followed by an ATP-dependent chelation step. The activation step may be the key to regulation, although variations in subunit levels during diurnal growth may also play a role in determining the flux through the Bchl/Chl and haem branches of the pathway.

Lyapunov-Based Control of Mechanical Systems

Abstract: 1 Introduction- 11 Lyapunov-Based Control- 12 Rigid Mechanical Systems- 13 Flexible Mechanical Systems- 14 Real-Time Control Implementation- References- 2 Control Techniques for Friction Compensation- 21 Introduction- 22 Reduced-Order Friction Model- 23 Control Designs for Reduced-Order Model- 231 Standard Adaptive Control- 232 Modular Adaptive Control- 233 Adaptive Setpoint Control- 234 Experimental Evaluation- 24 Full-Order Friction Model- 25 Control Designs for Full-Order Model- 251 Model-Based Control: Asymptotic Tracking- 252 Model-Based Control: Exponential Tracking- 253 Adaptive Control: Case- 254 Adaptive Control: Case- 255 Experimental Evaluation- 26 Notes- References- 3 Full-State Feedback Tracking Controllers- 31 Introduction- 32 System Model- 33 Problem Statement- 34 Standard Adaptive Control- 341 Controller Formulation- 342 Stability Result- 35 Desired Trajectory-Based Adaptive Control- 351 Controller Formulation- 352 Stability Results- 353 Experimental Results- 354 Nonadaptive Extensions- 36 Control/Adaptation Law Modularity- 361 Input-to-State Stability Result- 362 Position Tracking Result- 363 Experimental Results- 364 Discussion of Results- 37 Notes- References- 4 Output Feedback Tracking Controllers- 41 Introduction- 42 Problem Statement- 43 Model-Based Observer/Control- 431 Velocity Observer Formulation- 432 Controller Formulation- 433 Composite Stability Result- 434 Experimental Results- 44 Linear Filter-Based Adaptive Control- 441 Filter Formulation- 442 Controller Formulation- 443 Composite Stability Result- 444 Experimental Results- 445 Nonadaptive Extensions- 45 Nonlinear Filter-Based Adaptive Control- 451 Filter/Controller Formulation- 452 Composite Stability Result- 453 OFB Form of Filter/Controller- 454 Simulation Results- 455 Extensions- 46 Notes- References- 5 Strings and Cables- 51 Introduction- 52 Actuator-String System- 521 System Model- 522 Problem Statement- 523 Model-Based Control Law- 524 Adaptive Control Law- 525 Extensions- 526 Experimental Evaluation- 53 Cable System- 531 System Model- 532 Problem Statement- 533 Model-Based Control Law- 534 Adaptive Control Law- 535 Experimental Evaluation- 54 Notes- References- 6 Cantilevered Beams- 61 Introduction- 62 Euler-Bernoulli Beam- 621 System Model- 622 Problem Statement- 623 Model-Based Control Law- 624 Adaptive Control Law- 625 Extensions- 626 Experimental Evaluation- 63 Timoshenko Beam- 631 System Model- 632 Problem Statement- 633 Model-Based Control Law- 634 Adaptive Control Law- 635 Simulation Results- 64 Notes- References- 7 Boundary Control Applications- 71 Introduction- 72 Axially Moving String System- 721 System Model- 722 Problem Statement- 723 Model-Based Control Law - 724 Adaptive Control Law- 725 Experimental Evaluation- 73 Flexible Link Robot Arm- 731 System Model- 732 Problem Statement- 733 Model-Based Control Law- 734 Adaptive Control Law- 735 Experimental Evaluation- 74 Flexible Rotor System- 741 System Model- 742 Problem Statement- 743 Model-Based Control Law- 744 Adaptive Control Law- 745 Experimental Evaluation- 75 Notes- References- Appendices- A Mathematical Background- References- B Bounds for General Rigid Mechanical System- References- C Bounds for the Puma Robot- References- D Control Programs- D1 DCAL Controller- D2 Flexible Rotor

Tracheal Respiration in Insects Visualized with Synchrotron X-ray Imaging

Abstract: Insects are known to exchange respiratory gases in their system of tracheal tubes by using either diffusion or changes in internal pressure that are produced through body motion or hemolymph circulation. However, the inability to see inside living insects has limited our understanding of their respiration mechanisms. We used a synchrotron beam to obtain x-ray videos of living, breathing insects. Beetles, crickets, and ants exhibited rapid cycles of tracheal compression and expansion in the head and thorax. Body movements and hemolymph circulation cannot account for these cycles; therefore, our observations demonstrate a previously unknown mechanism of respiration in insects analogous to the inflation and deflation of vertebrate lungs.