Ca2+ binding to myofibrillar regulatory sites can produce conformational changes allowing cross-bridge attachment and cycling. Measurements of smooth muscle actomyosin ATPase activity suggested that ...Ca2+ might act indirectly to mediate cross-bridge attachment by stimulating myosin light chain phosphorylation. However, the predicted obligatory relationship between developed force and myosin phosphorylation was not always observed in living smooth muscle. The observation that myosin phosphorylation was always tightly correlated with average cross-bridge cycling rates estimated from isotonic shortening velocities suggested that Ca2+ has two regulatory roles. One action is exerted via a Ca2+-binding protein whose identity is unknown in smooth muscle. This regulatory site acts like other Ca2+-binding regulatory proteins in muscle to permit cross-bridge interaction and to determine active stress. The second regulatory role involves stimulation of myosin light chain kinase and light chain phosphorylation. Increasing the level of phosphorylated cross-bridges increases shortening velocities or rate of force development. We suggest that the dephosphorylated cross-bridges are noncycling or slowly cycling in activated smooth muscle. Smooth muscle may be a particularly favorable experimental preparation for demonstrating a general regulatory role of myosin phosphorylation in modulating the kinetics and energetics of muscle contraction.
Overview and status of the power conditioning system for the National Ignition Facility Newton, M.A.; Fulkerson, E.S.; Hulsey, S.D. ...
PPPS-2001 Pulsed Power Plasma Science 2001. 28th IEEE International Conference on Plasma Science and 13th IEEE International Pulsed Power Conference. Digest of Papers (Cat. No.01CH37251),
2001, Volume:
1
Conference Proceeding
Open access
The National Ignition Facility (NIF) Power Conditioning System (PCS) is a modular capacitive energy storage system that provides over 34 kilojoules of energy to each of the nearly 8000 flashlamps in ...the NIF laser. Up to 400 megajoules of energy can be stored in the NIF PCS system, discharged through spark gaps and delivered to the flashlamps through a coaxial transmission line system requiring nearly 100 miles of high-voltage cable. The NIF PCS has been under development for nearly 4 years. During this time, the system was developed and designed by Sandia National Laboratory in Albuquerque, NM (SNLA) in conjunction with Lawrence Livermore National Laboratory (LLNL). Extensive reliability testing was performed at SNLA on the First Article NIF Test Module (FANTM) test facility and design improvements were implemented based on FANTM test results, leading to the final design presently undergoing system reliability testing at LLNL. Low-cost energy-storage capacitors, charging power supplies, and reliable, fault-tolerant components were developed through partnerships with numerous contractors. Extensive reliability and fault testing of components has also been performed. This paper provides an overview of the many efforts that have culminated in the final design of the NIF PCS. The PCS system design will be described and the cost tradeoffs discussed. Plans for fabrication and installation of the NIF PCS system over the next 6 years will be presented.
This chapter provides a wide range of examples that show the extensive role of computational simulation in the development of biological sciences. Computational simulations provide a powerful tool ...for understanding the complex biological systems at all scales. The increasing need for quantitative understanding of complex biological systems, in parallel with rapid developments in modern computers, has made computational simulations an integral part of biological research. Biological phenomena typically encompass a range of time and length scales, whose intrinsically complex interactions are critical to system function. With the development of new techniques, it will become increasingly feasible to couple the multiscale simulations of biological phenomena over a range of time and length scales. This represents both a challenge and an opportunity to understand a disease or biological process in its entirety.
In this work, we present the first AMBER observations, of the Wolf-Rayet and O (WR+O) star binary system y2 Velorum. The AMBER instrument was used with the telescopes UT2, UT3, and UT4 on baselines ...ranging from 46m to 85m. It delivered spectrally dispersed visibilities, as well as differential and closure phases, with a resolution R = 1500 in the spectral band 1.95-2.17 micron. We interpret these data in the context of a binary system with unresolved components, neglecting in a first approximation the wind-wind collision zone flux contribution. We show that the AMBER observables result primarily from the contribution of the individual components of the WR+O binary system. We discuss several interpretations of the residuals, and speculate on the detection of an additional continuum component, originating from the free-free emission associated with the wind-wind collision zone (WWCZ), and contributing at most to the observed K-band flux at the 5% level. The expected absolute separation and position angle at the time of observations were 5.1±0.9mas and 66±15° respectively. However, we infer a separation of 3.62+0.11-0.30 mas and a position angle of 73+9-11°. Our analysis thus implies that the binary system lies at a distance of 368+38-13 pc, in agreement with recent spectrophotometric estimates, but significantly larger than the Hipparcos value of 258+41-31 pc.
New Analyses of Echinoderms Clarke, F. W.; Kamm, R. M.
Proceedings of the National Academy of Sciences - PNAS,
06/1917, Volume:
3, Issue:
6
Journal Article
Four months after public screening for hypertension during the Swiss Trade Fair 1974, a random sample of 302 hypertensives referred to private practitioners were interviewed to determine the impact ...of the screening on longterm control through private practice. 201 hypertensives went for further blood pressure control: the previously aware did so more frequently than the previously unaware (p less than 0.01). 112 of 201 were confirmed as hypertensives by private practitioners: this occurred in 80% of aware but in only 36% of unaware patients. 94 were started on therapy. 76 of 112 (2/3) received further appointments. Another 101 hypertensives did not seek care. Main determinants were insufficient knowledge about hypertensive disease and a shorter period of formal education; half of them claimed "they felt perfectly well". In summary one third did not seek care, another third were not confirmed as hypertensive or were lost to follow-up, and only one third (50% of the aware and 10% of the unaware) were still under regular care. While community-wide screening provided an opportunity for educational compaigns and positively affected the behaviour of hypertensives who were already aware, the yield in terms of newly identified hypertensives still under control 4 months later was extremely low. Before further developing community screening programs, feasibility studies must define mechanism for improved longterm control.
Androsterone and Related Sterols Marker, Russell E; Whitmore, Frank C; Kamm, Oliver ...
Journal of the American Chemical Society,
02/1936, Volume:
58, Issue:
2
Journal Article
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