386 research outputs found

    Duration of the Electromyographic Silent Period Following the Jaw-Jerk Reflex in Human Subjects

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    During voluntary jaw clenching, a sharp tap to the menton of the mandible resulted in a transitory silent period (pause) in the electromyographic activity of the masseter and anterior temporalis muscles. Factors that could influence the duration of the silent period were studied, including direction and magnitude of the stimulus applied by the operator, the amount of muscular effort exerted by the subjects, and varying occlusal vertical dimensions. Decreased isometric muscle force resulted in statistically significant increases in silent period durations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67989/2/10.1177_00220345770560061501.pd

    A physicochemical roadmap of yeast replicative aging

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    Cellular aging is a multifactorial process that is characterized by a decline in homeostatic capacity, best described at the molecular level. Physicochemical properties such as pH and macromolecular crowding, are essential to all molecular processes in cells and require maintenance. Whether a drift in physicochemical properties contributes to the overall decline of homeostasis in aging is not known. Here we show that the cytosol of yeast cells acidifies modestly in early aging and sharply after senescence. Using a macromolecular crowding sensor optimized for long-term FRET measurements, we show the macromolecular crowding changes less in longer-lived cells in contrast to shorter-lived cells. While the average pH and crowding levels change only modestly with aging, we observe drastic changes in organellar volume, leading to crowding on the µm scale, which we term organellar crowding. Our measurements provide an initial framework of physicochemical parameters of replicatively-aged yeast cells

    A physicochemical perspective of aging from single-cell analysis of pH, macromolecular and organellar crowding in yeast

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    Cellular aging is a multifactorial process that is characterized by a decline in homeostatic capacity, best described at the molecular level. Physicochemical properties such as pH and macromolecular crowding are essential to all molecular processes in cells and require maintenance. Whether a drift in physicochemical properties contributes to the overall decline of homeostasis in aging is not known. Here we show that the cytosol of yeast cells acidifies modestly in early aging and sharply after senescence. Using a macromolecular crowding sensor optimized for long-term FRET measurements, we show that crowding is rather stable and that the stability of crowding is a stronger predictor for lifespan than the absolute crowding levels. Additionally, in aged cells we observe drastic changes in organellar volume, leading to crowding on the µm scale, which we term organellar crowding. Our measurements provide an initial framework of physicochemical parameters of replicatively aged yeast cells

    A physicochemical perspective of aging from single-cell analysis of ph, macromolecular and organellar crowding in yeast

    Get PDF
    Cellular aging is a multifactorial process that is characterized by a decline in homeostatic capacity, best described at the molecular level. Physicochemical properties such as pH and macromolecular crowding are essential to all molecular processes in cells and require maintenance. Whether a drift in physicochemical properties contributes to the overall decline of homeostasis in aging is not known. Here we show that the cytosol of yeast cells acidifies modestly in early aging and sharply after senescence. Using a macromolecular crowding sensor optimized for long-term FRET measurements, we show that crowding is rather stable and that the stability of crowding is a stronger predictor for lifespan than the absolute crowding levels. Additionally, in aged cells we observe drastic changes in organellar volume, leading to crowding on the µm scale, which we term organellar crowding. Our measurements provide an initial framework of physicochemical parameters of replicatively aged yeast cells. © 2020, eLife Sciences Publications Ltd. All rights reserved

    Radio Astronomy

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    Contains research objectives, summary of research and reports on six research projects.National Aeronautics and Space Administration (Grant NGL 22-009-016)National Aeronautics and Space Administration (Grant NGR 22-009-421)National Aeronautics and Space Administration (Langley Research Center Contract NAS1-10693)National Science Foundation (Grant GP-20769A#2)National Science Foundation (Grant GP-21348A#2)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300U. S. Air Force -- Wright-Patterson (Contract F33615-72-C-2129)California Institute of Technology Contract 952568M.I.T. Sloan Fund for Basic Research (Grant 241)M.I.T. Thomas C. Desmond Fun

    Radio Astronomy

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    Contains research objectives and summary of research on seven research projects.M.I.T. Sloan Fund for Basic ResearchNational Aeronautics and Space Administration (Contract NAS5-21980)National Aeronautics and Space Administration (Contract NAS5-22485)National Aeronautics and Space Administration (Contract NAS5-23677)National Aeronautics and Space Administration (Contract NAS5-22929)U. S. Air Force - Electronic Systems Division (Contract F19628-75-C-0122)National Science Foundation (Grant AST73-05043-A02)National Science Foundation (Grant AST73-05042-A03

    Radio Astronomy

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    Contains reports on eight research projects.National Aeronautics and Space Administration, Langley Research Center (Contract NAS1-10693)California Institute of Technology Contract 952568Joint Services Electronics Programs (U. S. Army, U.S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300National Science Foundation (Grant GP-20769A#1)National Science Foundation (Grant GP-21348A#1

    Radio Astronomy

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    Contains reports on three research project.National Science Foundation (Grant GP-21348A#2)California Institute of Technology (Contract 952568)National Aeronautics and Space Administration (Grant NGR 22-009-421)U. S. Air Force - Electronic Systems Division (Contract F19628-73-C-0196

    Radio Astronomy

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    Contains reports on four research projects.Joint Services Electronics Program (Contract DAAB07-71-C-0300)California Institute of Technology (Contract 952568)National Aeronautics and Space Administration (Contract NAS1-10693)National Science Foundation (Grant GP-21348A#2
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