An experimental system for analysis of the dynamic sap-flow characteristics in young trees: results of a beech tree

2004 ◽  
Vol 31 (1) ◽  
pp. 83 ◽  
Author(s):  
Kathy Steppe ◽  
Raoul Lemeur
Keyword(s):  
Steady State ◽  
Water Flow ◽  
Sap Flow ◽  
Time Lag ◽  
Vapour Pressure Deficit ◽  
Experimental System ◽  
Rate Of Change ◽  
Good Correspondence ◽  
Internal Water ◽  
Beech Tree

This paper describes an experimental system designed for analysis of the dynamic water flow through young trees, complemented with test results of a 2-year-old beech tree (Fagus sylvatica L.). The system allows automatic and simultaneous measurements of a complex set of plant physiological processes at leaf, branch, stem and root levels [transpiration (E), sap flow (F) and diameter fluctuations (Δd)], in combination with the micrometeorological variables that control these processes [soil and air temperature (Ts and Ta), vapour pressure deficit of the air (D) and photosynthetically active radiation (PAR)]. A 2-d experimental period was used to study the whole-tree water transport dynamics of the young beech tree. Good correspondence between E of the leaves and F in the supporting branch was found. An increased time lag between the F measurements along the hydraulic pathway down towards the root system was observed, indicating the non-steady-state nature of the water flow. The daytime Δd of stem and branch revealed the depletion and the replenishment of internal water reserves. The daily amount of water withdrawn from internal storage was 5% of the total daily transpiration. A good linear relationship was found between the rate of change in internal water storage and the rate of change in stem diameter, having no time lag. We conclude that the data obtained with this system will allow experimental assessment of hydraulic properties in young trees and facilitate calibration of models for non-steady-state conditions of water flow in young trees.

Transpiration and stomatal conductance of mistletoe (Loranthus europaeus) and its host plant, downy oak (Quercus pubescens)

Biologia ◽  
2012 ◽  
Vol 67 (5) ◽  
Author(s):  
Josef Urban ◽  
Roman Gebauer ◽  
Nadezhda Nadezhdina ◽  
Jan Čermák
Keyword(s):  
Stomatal Conductance ◽  
Sap Flow ◽  
Time Lag ◽  
Global Radiation ◽  
Vapour Pressure Deficit ◽  
Quercus Pubescens ◽  
Area Unit ◽  
Leaf Area Unit ◽  
The Relationship ◽  
Monteith Equation

AbstractSap flow rate was measured in the crown of a solitary specimen of downy oak (Quercus pubescens) infested by mistletoe (Loranthus europaeus). Five oak branches and two mistletoe plants were selected for analysis. The seasonal sum of transpired water expressed per leaf area unit was five times higher in the mistletoe than in the oak. In addition, the diurnal curves of sap flow were different between the plants. In the morning, the sap flow measured in the mistletoe lagged one hour behind the sap flow measured in an oak branch unencumbered by mistletoe. In contrast, no time lag was observed in the evening. The proportion of water transpired at night relative to the total transpiration was 7% in both species. The stomatal conductances derived from the inverted Penman-Monteith equation and their dependence on global radiation and the vapour pressure deficit (D) revealed that D exerts a different behaviour in stomatal control of transpiration in the mistletoe. We also determined that the concentration of calcium in the leaf mass could serve as a proxy for transpiration rate, however the relationship was not proportional.

Respiration in man during metabolic alkalosis

1962 ◽  
Vol 17 (1) ◽  
pp. 33-37 ◽  
Author(s):  
Daniel J. Stone
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Lung Function ◽  
Gas Exchange ◽  
Metabolic Alkalosis ◽  
Time Lag ◽  
Respiratory Compensation ◽  
Arterial Ph ◽  
Oral Sodium ◽  
Ventilation Response

A steady state metabolic alkalosis was induced in two subjects over a period of several days utilizing oral sodium bicarbonate in dosages of 50 g/day. The purpose of inducing steady state metabolic alkalosis was to study the effects of such a state on the respiratory center responses to inspired gas mixtures, containing carbon dioxide, and to contrast these results with the control studies. The experiment was so designed that the arterial pH in both subjects tended to return toward normal in the presence of significant increases in blood bicarbonate. Repeated study of ventilation responses with room air and 4% and 6% carbon dioxide in inspired air revealed a definite and significant decrease in ventilation response to carbon dioxide during the periods of steady state alkalosis as compared to the control periods. Normal responses returned after some time lag. A consistent rise in paCOCO2 occurred with alkalosis, thus demonstrating respiratory compensation. In neither subject was total lung function or gas exchange affected by the alkalosis. The experiment was confirmed on several occasions with reproducible results. Note: (With the Research Assistance of Mary Di Lieto) Submitted on May 22, 1961

Semiparametric approach to pharmacokinetic-pharmacodynamic data

1989 ◽  
Vol 256 (4) ◽  
pp. R1005-R1010
Author(s):  
D. Verotta ◽  
S. L. Beal ◽  
L. B. Sheiner
Keyword(s):  
Steady State ◽  
Rate Constant ◽  
Drug Concentration ◽  
Venous Blood ◽  
Time Lag ◽  
Elimination Rate ◽  
Hysteresis Loops ◽  
Real Data ◽  
Elimination Rate Constant ◽  
Arterial Blood

A semiparametric model for analysis of pharmacokinetic (PK) and pharmacodynamic (PD) data arising from non-steady-state experiments is presented. The model describes time lag between drug concentration in a sampling compartment, e.g., venous blood (Cv), and drug effect (E). If drug concentration at the effect site (Ce) equilibrates with arterial blood concentration (Ca) slower than with Cv, a non-steady-state experiment yields E vs. Cv data describing a counterclockwise hysteresis loop. If Ce equilibrates with Ca faster than with Cv, clockwise hysteresis is observed. To model hysteresis, a parametric model is proposed linking (unobserved) Ca to Cv with elimination rate constant kappa ov and also linking Ca to Ce with elimination rate constant kappa oe. When kappa oe is greater than (or less than) kappa ov clockwise (or counterclockwise) hysteresis occurs. Given kappa oe and kappa ov, numerical (constrained) deconvolution is used to obtain the disposition function of the arterial compartment (Ha), and convolution is used to calculate Ce given Ha. The values of kappa oe and kappa ov are chosen to collapse the hysteresis loops to single curves representing the Ce-E (steady-state) concentration-response curve. Simulations, and an application to real data, are reported.

Heuristic control of bipedal running: steady-state and accelerated

Robotica ◽  
2011 ◽  
Vol 29 (6) ◽  
pp. 939-947
Author(s):  
A. D. Perkins ◽  
K. J. Waldron ◽  
P. J. Csonka
Keyword(s):  
Steady State ◽  
Experimental System ◽  
Legged Robots ◽  
Stable Steady State ◽  
Control Laws ◽  
Mechanical Coupling ◽  
Ankle Joints

SUMMARYThe design, control, and actuation of legged robots that walk is well established, but there remain unsolved problems for legged robots that run. In this work, dynamic principles are used to develop a set of heuristics for controlling bipedal running and acceleration. These heuristics are then converted into control laws for two very different bipedal systems: one with a high-inertia torso and prismatic knees and one with a low-inertia torso, articulated knees, and mechanical coupling between the knee and ankle joints. These control laws are implemented in simulation to achieve stable steady-state running, accelerating, and decelerating. Stable steady-state running is also achieved in a planar experimental system with a semiconstrained torso.

Nucleation rates and the kinetics of particle growth II. The birth and death process

1964 ◽  
Vol 277 (1369) ◽  
pp. 167-182 ◽  
Keyword(s):  
Steady State ◽  
Homogeneous Nucleation ◽  
Time Lag ◽  
Particle Growth ◽  
Statistical Problem ◽  
Death Process ◽  
Birth And Death Process ◽  
Growth Mechanisms ◽  
Nucleation Kinetics ◽  
Kinetics Of

The model considered in part I is generalized to include growth mechanisms in which the chemical reaction which proceeds at the particle-atm osphere interface is reversible, so that molecules may evaporate from a particle as well as condense upon it. The Becker-Döring-Zeldovich-Frenkel theory of homogeneous nucleation kinetics is then reviewed in the light of the known statistical problem of the birth -and -death process, and an improved approximation is introduced which significantly alters the calculated results. Both steady-state nucleation kinetics and the time lag problem are discussed.

Wavelet and cross correlation analysis on some climatology parameters of Nepal

BIBECHANA ◽  
2021 ◽  
Vol 18 (2) ◽  
pp. 105-116
Author(s):  
Babu Ram Tiwari ◽  
Jiyao Xu ◽  
Binod Adhikari ◽  
Narayan Prasad Chapagain
Keyword(s):  
Wavelet Transform ◽  
Correlation Analysis ◽  
Cross Correlation ◽  
Spectral Characteristics ◽  
Time Lag ◽  
Rate Of Change ◽  
Policy Implications ◽  
Sunspot Numbers ◽  
Cross Correlation Analysis ◽  
Convective Motions

This study has been performed to understand the relationship between sunspot numbers (SSN) with climatology related parameters like temperature and rainfall from 1901 to 2016. The spectral characteristics of sunspot numbers, temperature and rainfall have been observed using continuous wavelet transform. Cross-correlation analyses were also performed to find any relation among temperature, rainfall, and sunspot numbers. The 9–11 year periodicity of sunspot numbers confirmed by wavelet transform in annual scale. The periodicity of high-frequency signals is identified between 4 to 11 years whereas the low frequencies signal is found throughout the periods of observation for temperature. Similarly, it is clear that there is more concentration of power between 8–16 years for rainfall. Cross-correlation analysis shows that the sunspot numbers is highly correlated with rainfall and temperature (correlation coefficient ~ 0.8054). The time lag relationship resulted in the almost simultaneous linear relationship between the temperature, rainfall, and the SSN tendency. The development of convective motions over the subtropics might be affected by the time rate of change of SSN combined with the surface temperature changes of diverse time scales. The convective motions were mostly controlled by the available amount of water vapor and the stability of the atmosphere that had a strong connection with the heat capacity of the concerned region. To produce more authentic findings for policy implications, further comprehensive and appropriate research can be undertaken and implemented in this very important field. BIBECHANA 18 (2) (2021) 105-115

scholarly journals Sorption/Diffusion Contributions to the Gas Permeation Properties of Bi-Soft Segment Polyurethane/Polycaprolactone Membranes for Membrane Blood Oxygenators

Membranes ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 8
Author(s):  
Tiago M. Eusébio ◽  
Ana Rita Martins ◽  
Gabriela Pon ◽  
Mónica Faria ◽  
Pedro Morgado ◽  
...  
Keyword(s):  
Steady State ◽  
Soft Segment ◽  
Time Lag ◽  
Transient State ◽  
Gas Permeation ◽  
Dominant Factor ◽  
Atmospheric Gases ◽  
Equilibrium Conditions ◽  
Permeability Coefficients ◽  
Permeation Properties

Due to their high hemocompatibility and gas permeation capacity, bi-soft segment polyurethane/polycaprolactone (PU/PCL) polymers are promising materials for use in membrane blood oxygenators. In this work, both nonporous symmetric and integral asymmetric PU/PCL membranes were synthesized, and the permeation properties of the atmospheric gases N2, O2, and CO2 through these membranes were experimentally determined using a new custom-built gas permeation apparatus. Permeate pressure vs. time curves were obtained at 37.0 °C and gas feed pressures up to 5 bar. Fluxes, permeances, and permeability coefficients were determined from the steady-state part of the curves, and the diffusion and sorption coefficients were estimated from the analysis of the transient state using the time-lag method. Independent measurements of the sorption coefficients of the three gases were performed, under equilibrium conditions, in order to validate the new setup and procedure. This work shows that the gas sorption in the PU/PCL polymers is the dominant factor for the permeation properties of the atmospheric gases in these membranes.

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