Drug Pharmacokinetics during Constant Rate IV Infusion: The Steady-State Principle

2012 ◽  
pp. 230-245
Keyword(s):  
Steady State ◽  
Constant Rate ◽  
Drug Pharmacokinetics

Recent Studies of Tire Braking Performance

1973 ◽  
Vol 1 (2) ◽  
pp. 121-137 ◽  
Author(s):  
J. L. McCarty ◽  
T. J. W. Leland
Keyword(s):  
Steady State ◽  
Rapid Cycling ◽  
Single Cycle ◽  
Steering Angle ◽  
Slip Ratio ◽  
Factors Affecting ◽  
Braking Performance ◽  
Constant Rate

Abstract The results from recent studies of some factors affecting tire braking and cornering performance are presented together with a discussion of the possible application of these results to the design of aircraft braking systems. The first part of the paper is concerned with steady-state braking, that is, results from tests conducted at a constant slip ratio or steering angle or both. The second part deals with cyclic braking tests, both single cycle, where brakes are applied at a constant rate until wheel lockup is achieved, and rapid cycling of the brakes under control of a currently operational antiskid system.

Control of an adiabatic continuous reactor by feeding catalyst

1980 ◽  
Vol 45 (11) ◽  
pp. 2903-2918 ◽  
Author(s):  
Josef Horák ◽  
Zina Valášková ◽  
František Jiráček
Keyword(s):  
Steady State ◽  
Reaction Temperature ◽  
Continuous Reactor ◽  
Control Element ◽  
Inlet Temperature ◽  
Switching Cycle ◽  
Point Temperature ◽  
Set Point ◽  
Constant Rate ◽  
Laboratory Reactor

Algorithms have been presented, analyzed and experimentally tested to stabilize the reaction temperature at constant inlet temperature and composition of the feed by controlled dispensing of the catalyst. The information for the control element is the course of the reaction temperature. If the temperature of the reaction mixture is below the set point, the catalyst is being fed into the reactor at a constant rate. If the reaction temperature is higher the catalyst dispenser is blocked; dispensing of the catalyst is not resumed until the set point temperature has been reached again. The amount of catalyst added is a function of the duration of the switching cycle. The effect has been discussed of the form of this function on the course of the switching cycle. The results have been tested experimentally on a laboratory reactor controlled in an unstable steady state.

Resistance to Outflow of Cerebrospinal Fluid Determined by Bolus Injection Technique and Constant Rate Steady State Infusion in Humans

Neurosurgery ◽  
1985 ◽  
Vol 16 (3) ◽  
pp. 336-340 ◽  
Author(s):  
Michael Kosteljanetz
Keyword(s):  
Cerebrospinal Fluid ◽  
Steady State ◽  
Bolus Injection ◽  
Point Of View ◽  
Injection Technique ◽  
Communicating Hydrocephalus ◽  
Constant Rate ◽  
High Degree ◽  
Infusion Technique

Abstract Two methods for the determination of resistance to the outflow of cerebrospinal fluid, the bolus injection technique and the constant rate steady state infusion technique, were compared. Thirty-two patients with a variety of intracranial diseases (usually communicating hydrocephalus) were studied. There was a high degree of correlation between the resistance values obtained with the two methods, but values based on the bolus injection technique were systematically and statistically significantly lower than those obtained with the constant rate infusion test. From a practical point of view. both methods were found to be applicable in a clinical setting.

Salivary Flow Induction by Buccal Permucosal Pilocarpine in Anesthetized Beagle Dogs

1992 ◽  
Vol 71 (11) ◽  
pp. 1762-1767 ◽  
Author(s):  
M.L. Weaver ◽  
J.M. Tanzer ◽  
P.A. Kramer
Keyword(s):  
Steady State ◽  
Salivary Flow ◽  
Salivary Secretion ◽  
Reversed Phase ◽  
Use Of Data ◽  
Constant Rate ◽  
First Pass ◽  
Steady State Plasma Concentration ◽  
Anesthetized Dogs ◽  
Drug Solution

We tested whether permucosal delivery of pilocarpine nitrate could be used to elicit significant salivary secretion. Pilocarpine (pKa 6.6 at 37°C) was applied as solutions (pHs 5.6, 6.6, 7.6; 15 mg/mL) to the buccal mucosa (2.8 cm2) of 6 anesthetized dogs. Saliva was collected continuously from cannulated submandibular and parotid ducts and blood sampled during and after drug administration. Plasma pilocarpine levels were determined by reversed-phase HPLC. Absorption rates were determined by use of data from separate zero-order intravenous infusions to the same dogs. Pilocarpine was buccally absorbed at a constant rate of 72.9 ± 38.5 μg/kg/h following its application at pH 7.6. At this pH of the drug solution, the time to appearance of pilocarpine in blood plasma was 0.31 ± 0.08 h, and the time to appearance of salivary flow was 0.86 ± 0.32 h. A threshold dose of 32.9 ± 7.5 ug/kg was required to induce secretion with the pH 7.6 drug, the steady-state plasma concentration was 28.9 ± 19.3 ng/mL, and the steady-state submandibular flow rate was 0.14 ± 0.11 mL/ min/gland pair. Salivary flow induction was symmetrical and reached levels as high as 0.35 mL/min/submandibular gland pair without apparent tachyphylaxis. Results at pHs 5.6, 6.6, and 7.6 were consistent with the hypothesis that pilocarpine is primarily absorbed as un-ionized drug. The data indicate that transmucosal delivery of pilocarpine, avoiding "first pass" hepatic loss, may hold promise for the treatment of xerostomia.

Study of the ratcheting by the indentation fatigue method with a flat cylindrical indenter: Part I. Experimental study

2006 ◽  
Vol 21 (7) ◽  
pp. 1793-1797 ◽  
Author(s):  
B.X. Xu ◽  
Z.F. Yue
Keyword(s):  
Steady State ◽  
Fatigue Test ◽  
Indentation Depth ◽  
Fatigue Testing ◽  
Indentation Load ◽  
Compression Tests ◽  
Constant Rate ◽  
Secondary Stage ◽  
Indentation Fatigue ◽  
Analogous Equation

Generally, ratcheting is studied on round specimens under tension–compression tests with a nonzero mean load. This work explored the possibility of studying ratcheting by indentation fatigue with a flat cylindrical indenter. In the experiment, emphasis was concentrated on the influence of maximum indentation load (Pmax.), indentation load variance (ΔP = Pmax − Pmin) and frequency of cycling (f) on the indentation depth–cycle curves. The experimental results showed that the indentation depth–cycle curves are analogous to the conventional strain–cycle curve of uniaxial fatigue testing, which has a primary stage of decaying indentation depth per cycle followed by a secondary stage of nearly constant rate of indentation depth per cycle. It was found that the steady-state indentation depth per cycle is an approximate linear function of maximum indentation load (Pmax) and indentation load variance (ΔP = Pmax − Pmin) in the log–log grid. This relationship can be given with a power-law expression as an analogous equation of steady-state ratcheting rate. Further study showed that the influence of frequency of cycling on the steady state indentation depth per cycle can be ignored when the frequency of cycling exceeds a certain value. Finally, comparison was made between the conventional uniaxial fatigue test and indentation fatigue test for the steady-state stage. It was shown that the conventional uniaxial fatigue parameters can be obtained by the indentation fatigue method.

Approximate Correction for Unsteady Pressure Differential in a Capillary-Tube Gas Viscosimeter

1969 ◽  
Vol 36 (2) ◽  
pp. 171-180 ◽  
Author(s):  
K. R. van Doren ◽  
R. A. Guereca ◽  
H. P. Richardson ◽  
D. Cummins
Keyword(s):  
Steady State ◽  
Capillary Tube ◽  
Pressure Level ◽  
Constant Volume ◽  
Pressure Differential ◽  
Flow Rates ◽  
Unsteady Pressure ◽  
Constant Rate

Equations are developed which satisfactorily describe the change in the pressure differential with time for a closed, constant-volume system which utilizes a coiled-capillary tube and a constant-rate pump to determine gas viscosities. Viscosities are computed at transient, unsteady, and apparent-steady-state conditions. As long as the flow rates are not too high and the pressure level is not too low, the computed viscosities appear to be reliable.

THE FORMATION OF OESTROGENS BY THE AUTOTRANSPLANTED OVARY OF THE EWE PERFUSED IN VIVO WITH C19 STEROIDS

1970 ◽  
Vol 65 (2) ◽  
pp. 244-260 ◽  
Author(s):  
Andre Rado ◽  
John A. McCracken ◽  
David T. Baird
Keyword(s):  
Steady State ◽  
Luteinizing Hormone ◽  
Venous Blood ◽  
The Other ◽  
Temporary Increase ◽  
Main Route ◽  
Ovarian Artery ◽  
Constant Rate ◽  
Control Samples

ABSTRACT The autotransplanted ovary of the ewe was perfused in vivo via the ovarian artery with either 14C or 3H labelled C19 steroids. 17β-Oestradiol was the major phenolic steroid isolated in ovarian venous blood from either testosterone or androstenedione. Smaller amounts of oestrone were obtained but there was no 17α-oestradiol, oestriol nor conjugated oestrogens isolated. The yield of oestrogen was approximately ten fold greater from androstenedione than from testosterone suggesting that the main route of oestrogen biosynthesis in the ovine ovary is via the former steroid. The effect of infusing luteinizing hormone (LH) at the rate of 10 μg per hour on the conversion of androstenedione to 17β-oestradiol was measured in 5 experiments. In 2 experiments, when the steady state was not achieved, the increasing rate of conversion was halted. On the other hand LH resulted in a temporary increase followed by a decrease in the rate of conversion in the remaining 3 experiments in which there was a constant rate of conversion in the control samples. These results are compatible with the concept that LH stimulates the aromatisation of androstenedione to oestrogens by the ovary in vivo.

scholarly journals Constant rate of steady-state self-antigen trafficking from skin to regional lymph nodes

2006 ◽  
Vol 18 (11) ◽  
pp. 1541-1548 ◽  
Author(s):  
M. Yoshino ◽  
H. Yamazaki ◽  
L. D. Shultz ◽  
S.-I. Hayashi
Keyword(s):  
Steady State ◽  
Lymph Nodes ◽  
Regional Lymph Nodes ◽  
Constant Rate ◽  
Antigen Trafficking ◽  
Self Antigen

scholarly journals On spatial matchings: The first-in-first-match case

2021 ◽  
Vol 53 (3) ◽  
pp. 757-800
Author(s):  
Mayank Manjrekar
Keyword(s):  
Steady State ◽  
Euclidean Space ◽  
Compact Space ◽  
Arrival Time ◽  
Type Inequality ◽  
Stationary Regime ◽  
Constant Rate ◽  
The One ◽  
Opposite Color

AbstractWe describe a process where two types of particles, marked red and blue, arrive in a domain at a constant rate. When a new particle arrives into the domain, if there are particles of the opposite color present within a distance of 1 from the new particle, then, among these particles, it matches to the one with the earliest arrival time, and both particles are removed. Otherwise, the particle is simply added to the system. Additionally, particles may lose patience and depart at a constant rate. We study the existence of a stationary regime for this process, when the domain is either a compact space or a Euclidean space. In the compact setting, we give a product-form characterization of the stationary distribution, and then prove an FKG-type inequality that establishes certain clustering properties of the particles in the steady state.

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