scholarly journals Ionized calcium concentrations in squid axons.

1976 ◽  
Vol 67 (4) ◽  
pp. 433-467 ◽  
Author(s):  
R Dipolo ◽  
J Requena ◽  
F J Brinley ◽  
L J Mullins ◽  
A Scarpa ◽  
...  
Keyword(s):  
Steady State ◽  
Light Emission ◽  
Mean Value ◽  
Ionized Calcium ◽  
Initial Value ◽  
Light Levels ◽  
Light Measurement ◽  
Ca 50 ◽  
Subsequent Introduction

Values for ionized [Ca] in squid axons were obtained by measuring the light emission from a 0.1-mul drop of aequorin confined to a plastic dialysis tube of 140-mum diameter located axially. Ionized Ca had a mean value of 20 x 10(-9) M as judged by the subsequent introduction of CaEGTA/EGTA buffer (ratio ca. 0.1) into the axoplasm, and light measurement on a second aequorin drop. Ionized Ca in axoplasma was also measured by introducing arsenazo dye into an axon by injection and measuring the Ca complex of such a dye by multichannel spectrophotometry. Values so obtained were ca. 50 x 10(-9) M as calibrated against CaEGTA/EGTA buffer mixtures. Wth a freshly isolated axon in 10 mM Ca seawater, the aequorin glow invariably increased with time; a seawater [Ca] of 2-3 mM allowed a steady state with respect to [Ca]. Replacement of Na+ in seawater with choline led to a large increase in light emission from aequorin. Li seawater partially reversed this change and the reintroduction of Na+ brought light levels back to their initial value. Stimulation at 60/s for 2-5 min produced an increase in aequorin glow about 0.1% of that represented by the known Ca influx, suggesting operationally the presence of substantial Ca buffering. Treatment of an axon with CN produced a very large increase in aequorin glow and in Ca arsenazo formation only if the external seawater contained Ca.

scholarly journals On Riemann—Liouville and Caputo Fractional Forward Difference Monotonicity Analysis

Mathematics ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1303
Author(s):  
Pshtiwan Othman Mohammed ◽  
Thabet Abdeljawad ◽  
Faraidun Kadir Hamasalh
Keyword(s):  
Time Scale ◽  
Initial Value Problems ◽  
Mean Value ◽  
Mean Value Theorem ◽  
Discrete Fractional Calculus ◽  
Initial Value ◽  
Forward Difference ◽  
The Mean ◽  
Monotonicity Analysis ◽  
Monotonicity Results

Monotonicity analysis of delta fractional sums and differences of order υ∈(0,1] on the time scale hZ are presented in this study. For this analysis, two models of discrete fractional calculus, Riemann–Liouville and Caputo, are considered. There is a relationship between the delta Riemann–Liouville fractional h-difference and delta Caputo fractional h-differences, which we find in this study. Therefore, after we solve one, we can apply the same method to the other one due to their correlation. We show that y(z) is υ-increasing on Ma+υh,h, where the delta Riemann–Liouville fractional h-difference of order υ of a function y(z) starting at a+υh is greater or equal to zero, and then, we can show that y(z) is υ-increasing on Ma+υh,h, where the delta Caputo fractional h-difference of order υ of a function y(z) starting at a+υh is greater or equal to −1Γ(1−υ)(z−(a+υh))h(−υ)y(a+υh) for each z∈Ma+h,h. Conversely, if y(a+υh) is greater or equal to zero and y(z) is increasing on Ma+υh,h, we show that the delta Riemann–Liouville fractional h-difference of order υ of a function y(z) starting at a+υh is greater or equal to zero, and consequently, we can show that the delta Caputo fractional h-difference of order υ of a function y(z) starting at a+υh is greater or equal to −1Γ(1−υ)(z−(a+υh))h(−υ)y(a+υh) on Ma,h. Furthermore, we consider some related results for strictly increasing, decreasing, and strictly decreasing cases. Finally, the fractional forward difference initial value problems and their solutions are investigated to test the mean value theorem on the time scale hZ utilizing the monotonicity results.

Sickle cell crisis as evaluated from measurements of hydroxybutyrate dehydrogenase and myoglobin in plasma.

1981 ◽  
Vol 27 (2) ◽  
pp. 314-316 ◽  
Author(s):  
E F Roth ◽  
P A Bardfeld ◽  
S J Goldsmith ◽  
E Radel ◽  
J C Williams
Keyword(s):  
Steady State ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
High Specificity ◽  
Mean Value ◽  
Cell Disease ◽  
Sickle Cell Crisis ◽  
The Mean ◽  
Low Sensitivity ◽  
Sickle Cell Crises

Abstract Data on plasma hydroxybutyrate dehydrogenase activity (I) and myoglobin concentration were used to evaluate painful sickle cell crises. I was increased during non-crisis steady state in patients with sickle cell disease as compared to normal values (232, SD 79.7 vs 85, SD 33 Sigma units/mL). During crisis, the mean value for I increased further to 379 (SD 139) Sigma units/mL. For 12 patients evaluated both during steady state and crisis, there was a mean increase in plasma I of 131% (SD 76%). Repeated determinations of I in sickle cell disease patients during several months while they were in steady state showed that baseline I varied by no more than 20% from the mean. Plasma myoglobin in patients with sickle cell disease was not above normal, but during crisis 21 of 39 patients tested had increased plasma myoglobin concentrations. Our data suggest that I may be a useful indicator of sickle cell crisis when the patient's own baseline value is available for comparison. Plasma myoglobin measurements give evidence of muscle damage during crisis with high specificity but low sensitivity.

The Pharmacokinetics of a Single Dose of Calcitriol Administered Subcutaneously in Continuous Ambulatory Peritoneal Dialysis Patients

1993 ◽  
Vol 13 (2) ◽  
pp. 122-125 ◽  
Author(s):  
Rafael Selgas ◽  
Maria-E. Martinez ◽  
Blanca Miranda ◽  
Maria-Auxiliadara Baja ◽  
Jase-Raman Ramera ◽  
...  
Keyword(s):  
Single Dose ◽  
Peritoneal Dialysis ◽  
Continuous Ambulatory Peritoneal Dialysis ◽  
Plasma Levels ◽  
Subcutaneous Administration ◽  
Area Under The Curve ◽  
Serum Levels ◽  
Mean Value ◽  
Ionized Calcium ◽  
Kinetics Of

Objectives To evaluate the kinetics of calcitriol (1,25(OH)2D3) administered subcutaneously. Study Design Calcitriol kinetics and efficacy after subcutaneous administration were studied in 13 CAPD patients with varying degrees of increased plasma levels of parathyroid hormone (i-PTH). A single dose of 2 μg of calcitriol was administered subcutaneously, and its serum levels at baseline and after 1,2,6,12, and 24 hours were determined. Plasma ionized calcium and i-PTH were also determined at these periods. Results Serum calcitriol levels reached peak levels of 60 and 70 pg/mL at 1 and 2 hours after administration, respectively. These levels decreased thereafter, but remained above baseline values during 24 hours. The mean value of the area under the curve (AUC) was 809±226 pg/mL/hour. Plasma i-PTH levels showed a slight decrease after 1 and 2 hours, returning to baselime levels after this period. Plasma ionized calcium did not show significant changes during the study. A slight pain at the site of injection was mentioned by some patients. Conclusions The subcutaneous route for calcitriol administration achieves theoretically adequate plasma levels in continuous ambulatory peritoneal dialysis (CAPD) patients. This is important when paremteral administration of calcitriol is considered in the treatment of secondary hyperparathyroidism.

scholarly journals SURFACE TENSION OF SERUM

1922 ◽  
Vol 35 (5) ◽  
pp. 707-735 ◽  
Author(s):  
P. Lecomte du Noüy
Keyword(s):  
Surface Tension ◽  
Surface Layer ◽  
Free Surface ◽  
Organic Compounds ◽  
Sodium Oleate ◽  
Mean Value ◽  
Physiological Solution ◽  
Optimum Concentration ◽  
Initial Value ◽  
Ring Method

The application of the ring method to the measurement of solutions of serum and of certain organic compounds has brought forth new facts, mainly the decrease of the surface tension of such solutions in function of time. 1. In serum diluted at such a low concentration as 1:1,000,000 in NaCl, physiological solution, the surface tension of the liquid is lowered by 3 or 4 dynes in 2 hours; at 1:100,000, by about 11 dynes (mean value) in 2 hours, and by 20 dynes in 24 hours; at 1:10,000 by about 13 to 16 dynes in 2 hours. 2. The drop in surface tension is much more rapid in the first 30 minutes and follows generally the law of adsorption in the surface layer in function of the time. 3. Stirring or shaking after the drop causes the surface tension to rise, but generally below its initial value. 4. The same phenomena occur when using sodium oleate, glycocholate, or saponin instead of serum. 5. For every serum, as well as for the substances mentioned above a maximum drop occurs in certain conditions at a given optimum concentration. 6. Not only are the substances which lower the surface tension adsorbed in the surface layer, in the case in which they are present with crystalloids, but also the crystalloids themselves, in contradiction to Gibbs' statement. This is plainly shown by the evaporation of such solutions in watch-glasses which, instead of a small group of sharp, large, well defined crystals at the bottom, leaves a white disc almost as large as the initial free surface itself, due to the liberation of the salt by the surface layer as it crawls down the concave surface of the glass. 7. In these conditions, solutions of serum are characterized by a very peculiar periodic and concentric distribution of the crystals, at a concentration of 1:100 only. The same ring-like aspect is observed with sodium oleate, glycocholate, and saponin, but not at the same concentration, as was to be expected, since serum is a solution in itself.

The Dynamics of Cumulative Step Size Adaptation on the Ellipsoid Model

2016 ◽  
Vol 24 (1) ◽  
pp. 25-57 ◽  
Author(s):  
Hans-Georg Beyer ◽  
Michael Hellwig
Keyword(s):  
Steady State ◽  
Linear Convergence ◽  
Search Space ◽  
Mean Value ◽  
Superior Performance ◽  
Noisy Environments ◽  
Step Size ◽  
State Behavior ◽  
Closed Form Solutions ◽  
The Mean

The behavior of the [Formula: see text]-Evolution Strategy (ES) with cumulative step size adaptation (CSA) on the ellipsoid model is investigated using dynamic systems analysis. At first a nonlinear system of difference equations is derived that describes the mean value evolution of the ES. This system is successively simplified to finally allow for deriving closed-form solutions of the steady state behavior in the asymptotic limit case of large search space dimensions. It is shown that the system exhibits linear convergence order. The steady state mutation strength is calculated, and it is shown that compared to standard settings in [Formula: see text] self-adaptive ESs, the CSA control rule allows for an approximately [Formula: see text]-fold larger mutation strength. This explains the superior performance of the CSA in non-noisy environments. The results are used to derive a formula for the expected running time. Conclusions regarding the choice of the cumulation parameter c and the damping constant D are drawn.

Onset of submaximal exercise in thoroughbred horses

1987 ◽  
Vol 65 (10) ◽  
pp. 2513-2518 ◽  
Author(s):  
Jean-Michel Weber ◽  
Wade S. Parkhouse ◽  
Geoffrey P. Dobson ◽  
Joyce C. Harman ◽  
David H. Snow ◽  
...  
Keyword(s):  
Heart Rate ◽  
Steady State ◽  
Cardiovascular Response ◽  
Lactate Concentration ◽  
Mean Value ◽  
Plasma Lactate ◽  
Work Intensity ◽  
Thoroughbred Horses ◽  
Plasma Lactate Concentration ◽  
Intensity Of Exercise

Plasma lactate concentration, hematocrit, and heart rate were measured during a 40-min trot (3–4 m/s, 6% incline) and a 15-min canter (6.5 m/s, 0% incline) in catheterized thoroughbred horses running on a treadmill to characterize the transient changes in plasma lactate concentration during the onset of exercise, and to determine if and when a steady state was established. The intensity of exercise had an effect on the pattern of changes observed for the three variables investigated. Mean hematocrit rose from 38.5% at rest to 52.0% after a 4-min walk (1.6 m/s) and to 57.7% after 3 min of subsequent trotting (4 m/s). The highest mean value of 58.7% was reached after 3 min of cantering. A slow but significant decrease in hematocrit was measured between the time maximum levels were attained for each work intensity and the end of exercise. During the onset of submaximal work, plasma lactate concentration, hematocrit, and heart rate all reached a maximum simultaneously. The rapid cardiovascular response of thoroughbreds (strong hematocrit increase and heart-rate overshoot) did not prevent them from temporarily relying on anaerobic metabolism, as shown by a marked lactate overshoot before a steady state was established. The observed changes in lactate concentration are explained by a model predicting lactate fluxes to and from the plasma compartment during the transition from the resting steady state to the exercise steady state. Biopsies of the middle gluteal muscle were taken before and after the canter protocol to measure the metabolic intermediates of the glycogenolytic pathway. The resting and postexercise concentrations of these intermediates were not different except for a 30% reduction in glycogen. Aerobic glycogenolysis was the main pathway for energy metabolism in the middle gluteus and, as in plasma, a metabolic steady state was established in this muscle.

A Control Oriented SI and HCCI Hybrid Combustion Model for Internal Combustion Engines

2010 ◽  
Author(s):  
Xiaojian Yang ◽  
Guoming G. Zhu ◽  
Zongxuan Sun
Keyword(s):  
Steady State ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Fuel Efficiency ◽  
Combustion Process ◽  
Internal Combustion ◽  
Mean Value ◽  
Combustion Model ◽  
Zone Model ◽  
Transient Control

The combustion mode transition between SI (spark ignited) and HCCI (Homogeneously Charged Compression Ignition) of an IC (Internal Combustion) engine is challenge due to the thermo inertia of residue gas; and model-based control becomes a necessity. This paper presents a control oriented two-zone model to describe the hybrid combustion that starts with SI combustion and ends with HCCI combustion. The gas respiration dynamics were modeled using mean-value approach and the combustion process was modeled using crank resolved method. The developed model was validated in an HIL (Hardware-In-the-Loop) simulation environment for both steady-state and transient operations in SI, HCCI, and SI-HCCI hybrid combustion modes through the exhaust valve timing control (recompression). Furthermore, cooled external EGR (exhaust gas re-circulation) was used to suppress engine knock and enhance the fuel efficiency. The simulation results also illustrates that the transient control parameters of hybrid combustion is quite different from these in steady state operation, indicating the need of a control oriented SI-HCCI hybrid combustion model for transient combustion control.

scholarly journals On determinism and well-posedness in multiple time dimensions

2009 ◽  
Vol 465 (2110) ◽  
pp. 3023-3046 ◽  
Author(s):  
Walter Craig ◽  
Steven Weinstein
Keyword(s):  
Initial Value Problem ◽  
Mean Value ◽  
Uniqueness Result ◽  
Mean Value Theorem ◽  
Multiple Time ◽  
Fourier Synthesis ◽  
Initial Value ◽  
Codimension One ◽  
The Cauchy Problem ◽  
Arbitrary Space

We study the initial value problem for the wave equation and the ultrahyperbolic equation for data posed on initial hypersurfaces surface of arbitrary space–time signature. We show that, under a non-local constraint, the initial value problem posed on codimension-one hypersurfaces—the Cauchy problem—has global unique solutions in the Sobolev spaces H m . Thus, it is well-posed. However, we show that the initial value problem on higher codimension hypersurfaces is ill-posed due to failure of uniqueness, at least when specifying a finite number of derivatives of the data. This failure is in contrast to a uniqueness result for data given in an arbitrary neighbourhood of such initial hypersurfaces, which Courant deduces from Asgeirsson’s mean value theorem. We give a generalization of Courant’s theorem that extends to a broader class of equations. The proofs use Fourier synthesis and the Holmgren–John uniqueness theorem.

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