Adaptation in the respiratory control system

2003 ◽  
Vol 81 (8) ◽  
pp. 765-773 ◽  
Author(s):  
James Duffin ◽  
Safraaz Mahamed
Keyword(s):  
Experimental Data ◽  
Control System ◽  
Steady State ◽  
Graphical Model ◽  
Respiratory Control ◽  
Ventilatory Responses ◽  
System A ◽  
Hypoxia Adaptation ◽  
Peripheral Chemoreflex

Exposure to hypoxia, whether for short or prolonged periods or for repeated episodes, produces alterations in the ventilatory responses. This review presents evidence that these adaptations are likely to be mediated by adaptations in the respiratory chemoreflexes, particularly the peripheral chemoreflex, and proposes models of respiratory control explaining the observed changes in ventilation. After a brief introduction to the respiratory control system, a graphical model is developed that illustrates the operation of the system in the steady state, which will be used later. Next, the adaptations in ventilatory responses to hypoxia that have been observed are described, and methods of measuring the alterations in the chemoreflexes that might account for them are discussed. Finally, experimental data supporting the view that changes in the activity of the peripheral chemoreflex can account for the ventilatory adaptations to hypoxia are presented and incorporated into models of chemoreflex behaviour during exposures to hypoxia of various durations.Key words: respiration, chemoreflexes, hypoxia, adaptation, models.

Maturation of respiratory control and the propensity for breathing instability in a sheep model

2009 ◽  
Vol 107 (5) ◽  
pp. 1463-1471 ◽  
Author(s):  
Bradley A. Edwards ◽  
Scott A. Sands ◽  
Elizabeth M. Skuza ◽  
Vojta Brodecky ◽  
Elaine M. Stockx ◽  
...  
Keyword(s):  
Control System ◽  
Steady State ◽  
Respiratory Control ◽  
Periodic Breathing ◽  
Loop Gain ◽  
Limited Evidence ◽  
Sheep Model ◽  
Ventilatory Responses ◽  
Gas Inhalation ◽  
Surrogate Measures

Limited evidence suggests that the ventilatory interaction between O2 and CO2 is additive after birth and becomes multiplicative with postnatal development. Such a switch may be linked to the propensity for periodic breathing (PB) in infancy. To test this idea, we characterized the maturation of the respiratory controller and its effect on breathing stability in ∼10-day-old lambs and 6-mo-old sheep. We measured 1) carotid body sensitivity via dynamic ventilatory responses to step changes in O2 and CO2, 2) steady-state ventilatory sensitivity to CO2 under hypoxic and hyperoxic conditions, 3) the dependence of the apneic threshold on arterial Po2, and 4) the effect of hypoxic or hypercapnic gas inhalation during induced PB. Stability of the system was assessed using surrogate measures of loop gain. Peripheral sensitivity to O2 was higher in newborn than in older animals ( P < 0.05), but peripheral CO2 sensitivity was unchanged. Central CO2 sensitivity was reduced with age, but the slopes of the ventilatory responses to CO2 were the same in hypoxia and hyperoxia. Reduced arterial Po2 caused a leftward shift in the apneic threshold at both ages. Inspiration of hypoxic gas during PB immediately halted PB, whereas hypercapnia stopped PB only after one or two further PB cycles. We conclude that the controller in the sheep remains additive over the first 6 mo of life. Our results also show that the loop gain of the respiratory control system is reduced with age, possibly as a result of a reduction of peripheral O2 sensitivity.

Invited Review: Neuroplasticity in respiratory motor control

2003 ◽  
Vol 94 (1) ◽  
pp. 358-374 ◽  
Author(s):  
Gordon S. Mitchell ◽  
Stephen M. Johnson
Keyword(s):  
Control System ◽  
Neural Control ◽  
Developmental Plasticity ◽  
Biological Significance ◽  
Respiratory Control ◽  
System A ◽  
Cord Injury ◽  
Respiratory Plasticity ◽  
Considerable Work ◽  
Respiratory Gases

Although recent evidence demonstrates considerable neuroplasticity in the respiratory control system, a comprehensive conceptual framework is lacking. Our goals in this review are to define plasticity (and related neural properties) as it pertains to respiratory control and to discuss potential sites, mechanisms, and known categories of respiratory plasticity. Respiratory plasticity is defined as a persistent change in the neural control system based on prior experience. Plasticity may involve structural and/or functional alterations (most commonly both) and can arise from multiple cellular/synaptic mechanisms at different sites in the respiratory control system. Respiratory neuroplasticity is critically dependent on the establishment of necessary preconditions, the stimulus paradigm, the balance between opposing modulatory systems, age, gender, and genetics. Respiratory plasticity can be induced by hypoxia, hypercapnia, exercise, injury, stress, and pharmacological interventions or conditioning and occurs during development as well as in adults. Developmental plasticity is induced by experiences (e.g., altered respiratory gases) during sensitive developmental periods, thereby altering mature respiratory control. The same experience later in life has little or no effect. In adults, neuromodulation plays a prominent role in several forms of respiratory plasticity. For example, serotonergic modulation is thought to initiate and/or maintain respiratory plasticity following intermittent hypoxia, repeated hypercapnic exercise, spinal sensory denervation, spinal cord injury, and at least some conditioned reflexes. Considerable work is necessary before we fully appreciate the biological significance of respiratory plasticity, its underlying cellular/molecular and network mechanisms, and the potential to harness respiratory plasticity as a therapeutic tool.

scholarly journals Performance measurement of a 50-square-meter kite set-up on a 13-meter trawler

2019 ◽  
pp. 67-69
Author(s):  
Morgan Behrel ◽  
Kostia Roncin ◽  
Damien Grelon ◽  
Frédéric Montel ◽  
Alain Nême ◽  
...  
Keyword(s):  
Experimental Data ◽  
Control System ◽  
Wind Speed ◽  
Performance Measurement ◽  
Lift Coefficient ◽  
Post Processing ◽  
System A ◽  
Set Up ◽  
Drag Ratio ◽  
Lift To Drag Ratio

This paper describes an on board measurement campaign held in Grande-Rivière, Gaspésie, Province of Québec, Canada, in October 2015, involving a 13-meter trawler equipped with a 50-square-meter kite. The aim of the campaign was to access the boat performance when the kite is used for auxiliary propulsion. To achieve this purpose, in addition to the kite control system, a set of sensors was installed. During the trials, runs with kite in static flight were done, with around 12 knots of true wind speed. The data post processing is presented in this paper, and allows an estimate of the lift coefficient and the lift to drag ratio of the kite and the tethers. The collected data are consistent with other experimental data published.

USING NONLINEAR RESPIRATORY MECHANICS TO OPTIMIZE THE RESPIRATORY SIGNALS UNDER EUCAPNIC AND HYPERCAPNIC CONDITIONS

2015 ◽  
Vol 39 (3) ◽  
pp. 515-525
Author(s):  
Shyan-Lung Lin ◽  
Hsing-Cheng Chang ◽  
Yu-Zhe Tsai
Keyword(s):  
Flow Resistance ◽  
Respiratory Mechanics ◽  
Normal Load ◽  
Respiratory Control ◽  
Resistive Load ◽  
Breathing Frequency ◽  
Breathing Patterns ◽  
Ventilatory Responses ◽  
System A ◽  
Flow Through

In this study, the optimal chemical-mechanical respiratory control model was modified to include nonlinear respiratory mechanics with a lumped viscous resistance of the flow through the entire respiratory system, and a flow resistance that is proportional to the power of the flow rate. To evaluate the optimality of the system, a quadratic rising neuromuscular drive was applied to a neuro-mechanical effector and the respiratory signals were optimized under hypercapnia and eucapnia conditions. A continuous resistive load was imposed to compare the model behavior of respiratory mechanical loading with normal load. The optimized respiratory signals were demonstrated and the ventilatory responses with the optimized breathing patterns were examined. Our results showed that the nonlinear model acquired the intended level of ventilation with higher tidal volume VT and lower breathing frequency F during CO2 inhalation and lower VT and higher F during exercise.

Evidence on Food Control System in Charitable Food Assistance System: A Systematic Scoping Review

2018 ◽  
Author(s):  
Sizwe Makhunga ◽  
Tivani P. Mashamba-Thompson ◽  
Mbuzeleni Hlongwa ◽  
Khumbulani W. Hlongwana
Keyword(s):  
Control System ◽  
Scoping Review ◽  
Food Assistance ◽  
Assistance System ◽  
Food Control ◽  
System A

Isothermal and isobaric vapour-liquid equilibrium data in the tetrachloromethane-sec-butyl alcohol system

1983 ◽  
Vol 48 (9) ◽  
pp. 2446-2453 ◽  
Author(s):  
Jan Linek
Keyword(s):  
Experimental Data ◽  
Boiling Point ◽  
Butyl Alcohol ◽  
Correlation Equations ◽  
Wilson Equation ◽  
Liquid Equilibrium ◽  
Raoult’S Law ◽  
System A ◽  
Equilibrium Data ◽  
Alcohol System

Isothermal vapour-liquid equilibrium data at 65, 73 and 80 °C and isobaric ones at 101.3 kPa were measured in the tetrachloromethane-sec-butyl alcohol system. A modified circulation still of the Gillespie type was used for the measurements. Under the conditions of measurement, the system exhibits positive deviations from Raoult's law and minimum boiling-point azeotropes. The experimental data were fitted to a number of correlation equations, the most suitable being the Wilson equation.

Kinetic analysis of mechanism of intestinal Na+-dependent sugar transport

1985 ◽  
Vol 248 (5) ◽  
pp. C498-C509 ◽  
Author(s):  
D. Restrepo ◽  
G. A. Kimmich
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Sugar Transport ◽  
Enzyme Kinetic ◽  
Steady State Distribution ◽  
State Distribution ◽  
Least Squares Fit ◽  
Coupling Stoichiometry ◽  
Rate Limiting ◽  
Kinetics Of

Zero-trans kinetics of Na+-sugar cotransport were investigated. Sugar influx was measured at various sodium and sugar concentrations in K+-loaded cells treated with rotenone and valinomycin. Sugar influx follows Michaelis-Menten kinetics as a function of sugar concentration but not as a function of Na+ concentration. Nine models with 1:1 or 2:1 sodium:sugar stoichiometry were considered. The flux equations for these models were solved assuming steady-state distribution of carrier forms and that translocation across the membrane is rate limiting. Classical enzyme kinetic methods and a least-squares fit of flux equations to the experimental data were used to assess the fit of the different models. Four models can be discarded on this basis. Of the remaining models, we discard two on the basis of the trans sodium dependence and the coupling stoichiometry [G. A. Kimmich and J. Randles, Am. J. Physiol. 247 (Cell Physiol. 16): C74-C82, 1984]. The remaining models are terter ordered mechanisms with sodium debinding first at the trans side. If transfer across the membrane is rate limiting, the binding order can be determined to be sodium:sugar:sodium.

Multi-layer controller with state-constraint: Vehicle lateral stability control based on fuzzy logic

2021 ◽  
pp. 095440702110142
Author(s):  
Neng Wan ◽  
Guangping Zeng ◽  
Chunguang Zhang ◽  
Dingqi Pan ◽  
Songtao Cai
Keyword(s):  
Control System ◽  
Integrated Control ◽  
State Constraint ◽  
Stability Control ◽  
Lateral Stability ◽  
System A ◽  
Velocity Reduction ◽  
Vehicle Velocity ◽  
Allowable Range ◽  
Simulation Results

This paper deals with a new state-constrained control (SCC) system of vehicle, which includes a multi-layer controller, in order to ensure the vehicle’s lateral stability and steering performance under complex environment. In this system, a new constraint control strategy with input and state constraints is applied to calculate the steady-state yaw moment. It ensures the vehicle lateral stability by tracking the desired yaw rate value and limiting the allowable range of the side slip. Through the linkage of the three-layer controller, the tire load is optimized and achieve minimal vehicle velocity reduction. The seven-degree-of-freedom (7-DOF) simulation model was established and simulated in MATLAB to evaluate the effect of the proposed controller. Through the analysis of the simulation results, compared with the traditional ESC and integrated control, it not only solves the problem of obvious velocity reduction, but also solves the problem of high cost and high hardware requirements in integrated control. The simulation results show that designed control system has better performance of path tracking and driving state, which is closer to the desired value. Through hardware-in-the-loop (HIL) practical experiments in two typical driving conditions, the effectiveness of the above proposed control system is further verified, which can improve the lateral stability and maneuverability of the vehicle.

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