scholarly journals KINETICS OF ROD OUTER SEGMENT RENEWAL IN THE DEVELOPING MOUSE RETINA

1973 ◽  
Vol 58 (3) ◽  
pp. 650-661 ◽  
Author(s):  
Matthew M. LaVail
Keyword(s):  
Outer Segment ◽  
Photoreceptor Cells ◽  
Mouse Retina ◽  
Rod Photoreceptor ◽  
Adult Level ◽  
Rod Outer Segment ◽  
Equilibrium Length ◽  
Kinetics Of ◽  
Late Stages ◽  
Adult Rate

The kinetics of rod outer segment renewal in the developing retina have been investigated in C57BL/6J mice. Litters of mice were injected with [3H]amino acids at various ages and killed at progressively later time intervals. Plastic 1.5 µm sections of retina were studied by light microscope autoradiography. The rate of outer segment disk synthesis, as judged by labeled disk displacement away from the site of synthesis, is slightly greater than the adult level at 11–13 days of age; it rises to more than 1.6 times the adult rate between days 13 and 17, after which it falls to the adult level at 21–25 days. The rate of disk disposal, as measured by labeled disk movement toward the site of disposal, is less than 15% of the adult level at 11–13 days of age; it rises sharply to almost 70% of the adult level by days 13–15 and then more gradually approaches the adult rate. The net difference in rates of synthesis and disposal accounts for the rapid elongation of rod outer segments in the mouse between days 11 and 17 and the subsequent, more gradual elongation to the adult equilibrium length reached between days 19 and 25. The changing rate of outer segment disk synthesis characterizes the late stages of cytodifferentiation of the rod photoreceptor cells.

Inhibition of the p38 MAP kinase pathway destabilizes smooth muscle length during physiological loading

2002 ◽  
Vol 282 (5) ◽  
pp. L1117-L1121 ◽  
Author(s):  
Oren J. Lakser ◽  
Robert P. Lindeman ◽  
Jeffrey J. Fredberg
Keyword(s):  
Smooth Muscle ◽  
Map Kinase ◽  
Muscle Length ◽  
P38 Map Kinase ◽  
Force Fluctuations ◽  
Physiological Loading ◽  
Mitogen Activated Protein ◽  
Equilibrium Length ◽  
Map Kinase Pathway ◽  
Kinase Pathway

We tested the hypothesis that mechanical plasticity of airway smooth muscle may be mediated in part by the p38 mitogen-activated protein (MAP) kinase pathway. Bovine tracheal smooth muscle (TSM) strips were mounted in a muscle bath and set to their optimal length, where the active force was maximal (Fo). Each strip was then contracted isotonically (at 0.32 Fo) with ACh (maintained at 10−4 M) and allowed to shorten for 180 min, by which time shortening was completed and the static equilibrium length was established. To simulate the action of breathing, we then superimposed on this steady distending force a sinusoidal force fluctuation with zero mean, at a frequency of 0.2 Hz, and measured incremental changes in muscle length. We found that TSM strips incubated in 10 μM SB-203580-HCl, an inhibitor of the p38 MAP kinase pathway, demonstrated a greater degree of fluctuation-driven lengthening than did control strips, and upon removal of the force fluctuations they remained at a greater length. We also found that the force fluctuations themselves activated the p38 MAP kinase pathway. These findings are consistent with the hypothesis that inhibition of the p38 MAP kinase pathway destabilizes muscle length during physiological loading.

How long are tidal channels?

2009 ◽  
Vol 643 ◽  
pp. 479-494 ◽  
Author(s):  
G. SEMINARA ◽  
S. LANZONI ◽  
N. TAMBRONI ◽  
M. TOFFOLON
Keyword(s):  
Coastal Wetlands ◽  
Characteristic Length ◽  
Flow Speed ◽  
Tidal Flats ◽  
Field Observations ◽  
Sediment Characteristics ◽  
Tidal Channels ◽  
Analytical Treatment ◽  
Equilibrium Length ◽  
Inlet Conditions

Do tidal channels have a characteristic length? Given the sediment characteristics, the inlet conditions and the degree of channel convergence, can we predict it? And how is this length affected by the presence of tidal flats adjacent to the channel? We answer the above questions on the basis of a fully analytical treatment, appropriate for the short channels typically observed in coastal wetlands. The equilibrium length of non-convergent tidal channels is found to be proportional to the critical flow speed for channel erosion. Channel convergence causes concavity of the bed profile. Tidal flats shorten equilibrium channels significantly. Laboratory and field observations substantiate our findings.

scholarly journals THE ULTRASTRUCTURE OF STRIATED MUSCLE AT VARIOUS SARCOMERE LENGTHS

1956 ◽  
Vol 2 (4) ◽  
pp. 157-162 ◽  
Author(s):  
David Spiro
Keyword(s):  
Striated Muscle ◽  
Thin Filaments ◽  
Thick Filaments ◽  
Equilibrium Length

1. Rest and equilibrium length muscle sarcomeres are composed of thin filaments (actin) which traverse the sarcomeres from the Z membranes up to the H band; at this level the filaments are considerably thicker and less numerous. 2. Shortening of muscle is associated with a transformation of thin into thick filaments in the A band. 3. These observations are discussed in terms of interaction of actin and myosin to form a supercoiled structure as the basis of contraction.

scholarly journals Theory and Laboratory Observations of Naled Ice Growth

1986 ◽  
Vol 32 (111) ◽  
pp. 168-177
Author(s):  
G. A. Schohl ◽  
R. Ettema
Keyword(s):  
Mass Balance ◽  
Laboratory Data ◽  
Layer By Layer ◽  
Two Dimensional ◽  
Ice Growth ◽  
Laboratory Flume ◽  
Equilibrium Length ◽  
The Times ◽  
Data Length ◽  
Composite Description

AbstractBased on observations of naleds (also called aufeis or icings) grown in a refrigerated laboratory flume, a detailed, composite description of the processes associated with naled ice growth is presented. A spread length is derived that represents a mass balance between the water supplied to a naled’s surface and the ice that freezes on to the surface. Herein, this spread length is termed an equilibrium length. Guided by this concept of equilibrium length and the laboratory data, length- and time-scales applicable to the growth of two-dimensional naleds are proposed. These scales proved useful for normalizing the times and streamwise lengths that correspond to distinct phases of naled ice growth. It is observed that, even in a laboratory flume, naleds spread and thicken in a complex, layer-by-layer manner.To the best of the authors’ knowledge, this is the first reported laboratory study on naled ice growth. The descriptions and concepts presented herein should be useful to engineers concerned with the effects of naleds on engineering works, and of interest to those who are planning experiments on naleds.

Effect of Stimulation-Length Sequence on Shape of Length-Tension Diagram

1956 ◽  
Vol 186 (1) ◽  
pp. 127-130 ◽  
Author(s):  
B. A. Schottelius ◽  
L. C. Senay
Keyword(s):  
Total Length ◽  
Secondary Maximum ◽  
Working Hypothesis ◽  
Equilibrium Length ◽  
Tension Curves ◽  
Working Hypotheses

Length-tension diagrams have been obtained from rat gastrocnemii stimulated under various stimulation-length sequences. The sequences were selected in an attempt to discover the origin of a secondary maximum on active and total length-tension curves, when these were derived by a commonly accepted technique. Two working hypotheses were advanced. The results indicate that several length-tension characteristics are dependent upon stimulation-length sequence, and that under the conditions examined the most important of these characteristics are extensibility and equilibrium length. As a consequence, neither working hypothesis appeared entirely satisfactory.

The formation of cracks as a result of plastic flow

1954 ◽  
Vol 223 (1154) ◽  
pp. 404-414 ◽  
Keyword(s):  
Plastic Flow ◽  
Stable Equilibrium ◽  
Stress System ◽  
Equilibrium Length ◽  
Formation Of Cracks ◽  
Cold Worked

The stresses round a piled-up group of dislocations are investigated with reference to the initiation of a crack. A crack should form when the group consists of about 1000 dislocations piled up under a stress of the magnitude occurring in a cold-worked metal. The stress system due to the crack is obtained. The crack will have a stable equilibrium length, but this length is likely to be determined by the amount of plastic flow which takes place round the tip of the crack.

An r-Adaptive Technique for Unstructured Grids Based on the Segment Spring Analogy Method

2015 ◽  
Vol 12 (01) ◽  
pp. 1350091 ◽  
Author(s):  
X. Sun ◽  
J. Z. Zhang
Keyword(s):  
Unstructured Grids ◽  
Linear Parabolic Equation ◽  
Analogy Method ◽  
Convection Diffusion ◽  
Convection Diffusion Equation ◽  
Adaptive Technique ◽  
Estimate Method ◽  
Equilibrium Length ◽  
2D Euler Equations ◽  
The One

A simple and effective r-adaptive technique for unstructured grids based on the segment spring analogy method is proposed. The finite element method and a corresponding error estimate method using second derivatives are used for computation. The traditional segment spring analogy method is modified, based on an idea of controlling the equilibrium length of the fictitious springs, and used for mesh adjustment. The principle of making numerical errors distributed uniformly over all elements is applied. Three numerical examples involving the one-dimensional (1D) convection-diffusion equation, the two-dimensional (2D) linear parabolic equation and the 2D Euler equations are presented and the effectiveness of the proposed r-type grid adaptive technique is examined.

scholarly journals Structural and Optical Properties of α-Quartz Cluster with Oxygen-Deficiency Centers

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Yin Li ◽  
Xi Chen ◽  
Chuanghua Yang ◽  
Liyuan Wu ◽  
Ru Zhang
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Oxygen Deficiency ◽  
Cluster Models ◽  
Structural And Optical Properties ◽  
Theoretical Support ◽  
The Density Functional Theory ◽  
Metastable Structure ◽  
Time In Literature ◽  
Equilibrium Length

The structural and optical properties of α-quartz cluster with oxygen-deficiency centers (ODCs) defects have been investigated based on the density functional theory (DFT). For cluster models with ODC(I) defect, with the increasing of cluster size and shape, the equilibrium length of Si-Si bond decreases. The excitation peaks of cluster models with ODC(I) defect are from 6.87 eV to 7.39 eV, while the excitation peaks of cluster models with ODC(II) defect are from 5.20 eV to 5.47 eV. We also study the interconversion between ODCs (≡Si-Si≡ bond and divalent Si) induced by UV irradiation. Our study predicted the existence of a metastable structure of ODC(I) for the first time in literature. Our results are in good agreement with the previous results and provide strong theoretical support to the viability of the processes.

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