An Oscillatory Mechanism with a Flexible Accelerator

1982 ◽  
pp. 66-70
Author(s):  
R. M. Goodwin
Keyword(s):  
Oscillatory Mechanism

scholarly journals Rhythmic Serotonin N-Acetyltransferase mRNA Degradation Is Essential for the Maintenance of Its Circadian Oscillation

2005 ◽  
Vol 25 (8) ◽  
pp. 3232-3246 ◽  
Author(s):  
Tae-Don Kim ◽  
Jong-So Kim ◽  
Jong Heon Kim ◽  
Jihwan Myung ◽  
Hee-Don Chae ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Expression Patterns ◽  
Mrna Level ◽  
Mrna Degradation ◽  
Circadian Oscillation ◽  
Oscillatory Mechanism ◽  
Key Enzyme ◽  
Mrna Profile ◽  
Species Specific ◽  
Nuclear Ribonucleoprotein

ABSTRACT Serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase [AANAT]) is the key enzyme in melatonin synthesis regulated by circadian rhythm. To date, our understanding of the oscillatory mechanism of melatonin has been limited to autoregulatory transcriptional and posttranslational regulations of AANAT mRNA. In this study, we identify three proteins from pineal glands that associate with cis-acting elements within species-specific AANAT 3′ untranslated regions to mediate mRNA degradation. These proteins include heterogeneous nuclear ribonucleoprotein R (hnRNP R), hnRNP Q, and hnRNP L. Their RNA-destabilizing function was determined by RNA interference and overexpression approaches. Expression patterns of these factors in pineal glands display robust circadian rhythm. The enhanced levels detected after midnight correlate with an abrupt decline in AANAT mRNA level. A mathematical model for the AANAT mRNA profile and its experimental evidence with rat pinealocytes indicates that rhythmic AANAT mRNA degradation mediated by hnRNP R, hnRNP Q, and hnRNP L is a key process in the regulation of its circadian oscillation.

MULTI–INERT OSCILLATORY MECHANISM

2020 ◽  
Vol 2 ◽  
pp. 19-25
Author(s):  
I.P. POPOV
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Oscillation Frequency ◽  
Free Oscillation ◽  
Initial Conditions ◽  
Oscillatory System ◽  
Harmonic Oscillations ◽  
Oscillatory Systems ◽  
Oscillatory Mechanism ◽  
Mutual Conversion

A mechanical oscillatory system with homogeneous elements, namely, with n massive loads (multi– inert oscillator), is considered. The possibility of the appearance of free harmonic oscillations of loads in such a system is shown. Unlike the classical spring pendulum, the oscillations of which are due to the mutual conversion of the kinetic energy of the load into the potential energy of the spring, in a multi–inert oscillator, the oscillations are due to the mutual conversion of only the kinetic energies of the goods. In this case, the acceleration of some loads occurs due to the braking of others. A feature of the multi–inert oscillator is that its free oscillation frequency is not fixed and is determined mainly by the initial conditions. This feature can be very useful for technical applications, for example, for self–neutralization of mechanical reactive (inertial) power in oscillatory systems.

The Forces Exerted on the Substrate by Walking and Stationary Crickets

1980 ◽  
Vol 85 (1) ◽  
pp. 263-279 ◽  
Author(s):  
Jack Harris ◽  
Helen Ghiradella
Keyword(s):  
The Body ◽  
Peak Force ◽  
Vertical Force ◽  
Step Frequency ◽  
Oscillatory Mechanism ◽  
Lower Magnitude ◽  
Stationary Period

1. The gait and the protraction/retraction ratios (P/R ratios) for the cricket are described. They are essentially the same as for the cockroach and the grasshopper. 2. The vertical forces exerted on the substrate by all six legs of walking and stationary crickets are measured. On the basis of the ‘forceprints’ obtained and differences in P/R ratios among the legs of different thoracic segments, it is pointed out that all segments are not functionally identical. Specifically, the greater irregularity of the forceprints of the prothoracic legs, and the lower magnitude of peak force exerted on the substrate by the prothoracic legs suggest that the prothoracic legs are more involved in balancing or searching than in propulsion. 3. The metathoracic legs exert an increased vertical force on the substrate just before the initiation of protraction. This increase correlates with an extension of the leg apparently through extension of the femoraltibial joint. 4. A slight decrease in the force exerted on the substrate by the mesothoracic legs occurs when the leg is at right angles to the body. 5. Placing or lifting one mesothoracic leg does not affect the force exerted by the contralateral mesothoracic leg in a regular way. This argues against mechanical interactions between the legs and in favour of theories invoking central generation of pattern. 6. At a stepping frequency of below 2 steps s−1 the shapes of the forceprints of all legs are no longer repetitive. Also, below 2 steps s−1 there is an increase in the variability of the peak force exerted on the substrate. It is possible that the animal switches to a more sensory sensitive mode below a step frequency of 2s−1. 7. During stationary periods the forces exerted on the substrate continue to show oscillations which may be metachronal. This suggests a mechanism whereby a central oscillatory mechanism can account for the behaviour of an animal starting to walk following such a stationary period.

scholarly journals Optimal design and analysis of oscillatory mechanism for agricultural tillage operation

2019 ◽  
Vol 1 (9) ◽  
Author(s):  
N. R. N. V. Gowripathi Rao ◽  
Himanshu Chaudhary ◽  
A. K. Sharma
Keyword(s):  
Optimal Design ◽  
Oscillatory Mechanism ◽  
Tillage Operation

scholarly journals Membrane-bound MinDE complex acts as a toggle switch that drives Min oscillation coupled to cytoplasmic depletion of MinD

2016 ◽  
Vol 113 (11) ◽  
pp. E1479-E1488 ◽  
Author(s):  
Anthony G. Vecchiarelli ◽  
Min Li ◽  
Michiyo Mizuuchi ◽  
Ling Chin Hwang ◽  
Yeonee Seol ◽  
...  
Keyword(s):  
Standing Wave ◽  
Toggle Switch ◽  
Cell Pole ◽  
Wave Oscillator ◽  
Peripheral Ring ◽  
Oscillatory Mechanism ◽  
A Cell ◽  
The Mind

TheEscherichia coliMin system self-organizes into a cell-pole to cell-pole oscillator on the membrane to prevent divisions at the cell poles. Reconstituting the Min system on a lipid bilayer has contributed to elucidating the oscillatory mechanism. However, previous in vitro patterns were attained with protein densities on the bilayer far in excess of those in vivo and failed to recapitulate the standing wave oscillations observed in vivo. Here we studied Min protein patterning at limiting MinD concentrations reflecting the in vivo conditions. We identified “burst” patterns—radially expanding and imploding binding zones of MinD, accompanied by a peripheral ring of MinE. Bursts share several features with the in vivo dynamics of the Min system including standing wave oscillations. Our data support a patterning mechanism whereby the MinD-to-MinE ratio on the membrane acts as a toggle switch: recruiting and stabilizing MinD on the membrane when the ratio is high and releasing MinD from the membrane when the ratio is low. Coupling this toggle switch behavior with MinD depletion from the cytoplasm drives a self-organized standing wave oscillator.

Equilibrium Potential of GABAA Current and Implications for Rebound Burst Firing in Rat Subthalamic Neurons In Vitro

2000 ◽  
Vol 83 (5) ◽  
pp. 3169-3172 ◽  
Author(s):  
Mark D. Bevan ◽  
Charles J. Wilson ◽  
J. Paul Bolam ◽  
Peter J. Magill
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Low Frequency ◽  
Burst Firing ◽  
Oscillatory Activity ◽  
Equilibrium Potential ◽  
Oscillatory Mechanism ◽  
Subthalamic Neurons ◽  
Bursting Activity

Reciprocally connected glutamatergic subthalamic and GABAergic globus pallidus neurons have recently been proposed to act as a generator of low-frequency oscillatory activity in Parkinson's disease. To determine whether GABAA receptor-mediated synaptic potentials could theoretically generate rebound burst firing in subthalamic neurons, a feature that is central to the proposed oscillatory mechanism, we determined the equilibrium potential of GABAA current ( E GABAA ) and the degree of hyperpolarization required for rebound firing using perforated-patch recording. In the majority of neurons that fired rebounds, E GABAA was equal to or more hyperpolarized than the hyperpolarization required for rebound burst firing. These data suggest that synchronous activity of pallidal inputs could underlie rhythmic bursting activity of subthalamic neurons in Parkinson's disease.

scholarly journals Role of DBP in the Circadian Oscillatory Mechanism

2000 ◽  
Vol 20 (13) ◽  
pp. 4773-4781 ◽  
Author(s):  
Shun Yamaguchi ◽  
Shigeru Mitsui ◽  
Lily Yan ◽  
Kazuhiro Yagita ◽  
Shigeru Miyake ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Leucine Zipper ◽  
The Other ◽  
Suprachiasmatic Nuclei ◽  
Transcription Factor Family ◽  
Transcript Levels ◽  
Oscillatory Mechanism ◽  
Central Clock ◽  
E Boxes

ABSTRACT Transcript levels of DBP, a member of the PAR leucine zipper transcription factor family, exhibit a robust rhythm in suprachiasmatic nuclei, the mammalian circadian center. Here we report that DBP is able to activate the promoter of a putative clock oscillating gene,mPer1, by directly binding to the mPer1promoter. The mPer1 promoter is cooperatively activated by DBP and CLOCK-BMAL1. On the other hand, dbp transcription is activated by CLOCK-BMAL1 through E-boxes and inhibited by the mPER and mCRY proteins, as is the case for mPer1. Thus, a clock-controlled dbp gene may play an important role in central clock oscillation.

Frequency modulated translocational oscillations of Nrf2, a transcription factor functioning like a wireless sensor

2015 ◽  
Vol 43 (4) ◽  
pp. 669-673 ◽  
Author(s):  
Mingzhan Xue ◽  
Hiroshi Momiji ◽  
Naila Rabbani ◽  
Till Bretschneider ◽  
David A. Rand ◽  
...  
Keyword(s):  
Regulatory Control ◽  
Wireless Sensor ◽  
Related Factor ◽  
Nuclear Factor ◽  
Nrf2 Activation ◽  
Oscillatory Mechanism ◽  
Fit For Purpose ◽  
Experimental Findings ◽  
Cytoprotective Response

The discovery that nuclear factor erythroid 2-related factor 2 (Nrf2) undergoes translocational oscillations from cytoplasm to nucleus in human cells with frequency modulation linked to activation of a stress-stimulated cytoprotective response raises the prospect that the Nrf2 works mechanistically analogous to a wireless sensor. Herein, we consider how this new model of Nrf2 oscillation resolves previous inexplicable experimental findings on Nrf2 regulation and why it is fit-for-purpose. Further investigation is required to assess how generally applicable the oscillatory mechanism is and if characteristics of this regulatory control can be found in vivo. It suggests there are multiple, potentially re-enforcing receptors for Nrf2 activation, indicating that potent Nrf2 activation for improved health and treatment of disease may be achieved through combination of Nrf2 system stimulants.

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