scholarly journals Hydrodynamic stress and phenotypic plasticity of the zebrafish regenerating fin

2021 ◽  
Author(s):  
Paule Dagenais ◽  
Simon Blanchoud ◽  
David Pury ◽  
Catherine Pfefferli ◽  
Tinri Aegerter-Wilmsen ◽  
...  
Keyword(s):  
Developmental Process ◽  
Growth Dynamics ◽  
Feedback Mechanism ◽  
Fine Tuning ◽  
Distal Margin ◽  
Extrinsic Factors ◽  
Hydrodynamic Stress ◽  
Viscous Shear Stress ◽  
Viscous Shear ◽  
Locomotory Organ

Understanding how extrinsic factors modulate genetically encoded information to produce a specific phenotype is of prime scientific interest. In particular, the feedback mechanism between abiotic forces and locomotory organs during morphogenesis to achieve efficient movement is a highly relevant example of such modulation. The study of this developmental process can provide unique insights on the transduction of cues at the interface between physics and biology. Here, we take advantage of the natural ability of adult zebrafish to regenerate their amputated fins to assess its morphogenic plasticity upon external modulations. Using a variety of surgical and chemical treatments, we are able to induce phenotypic responses to the structure of the fin. Through the ablation of specific rays in regenerating caudal fins, we generate artificially narrowed appendages in which the fin cleft depth and the positioning of rays bifurcations are perturbed compared to normal regenerates. To dissect the role of mechanotransduction in this process, we investigate the patterns of hydrodynamic forces acting on the surface of a zebrafish fin during regeneration by using particle tracking velocimetry on a range of biomimetic hydrofoils. This experimental approach enables us to quantitatively compare hydrodynamic stress distributions over flapping fins of varying sizes and shapes. As a result, viscous shear stress acting on the distal margin of regenerating fins and the resulting internal tension are proposed as suitable signals for guiding the regulation of ray growth dynamics and branching pattern. Our findings suggest that mechanical forces are involved in the fine-tuning of the locomotory organ during fin morphogenesis.

scholarly journals Hydrodynamic stress and phenotypic plasticity of the zebrafish regenerating fin

2021 ◽  
Author(s):  
Paule Dagenais ◽  
Simon Blanchoud ◽  
David Pury ◽  
Catherine Pfefferli ◽  
Tinri Aegerter-Wilmsen ◽  
...  
Keyword(s):  
Developmental Process ◽  
Growth Dynamics ◽  
Feedback Mechanism ◽  
Fine Tuning ◽  
Stress Distributions ◽  
Extrinsic Factors ◽  
Hydrodynamic Stress ◽  
Viscous Shear Stress ◽  
Viscous Shear ◽  
Locomotory Organ

AbstractUnderstanding how extrinsic factors modulate genetically encoded information to produce a specific phenotype is of prime scientific interest. In particular, the feedback mechanism between abiotic forces and locomotory organs during morphogenesis to achieve efficient movement is a highly relevant example of such modulation. The study of this developmental process can provide unique insights on the transduction of cues at the interface between physics and biology. Here, we take advantage of the natural ability of adult zebrafish to regenerate their amputated fins to assess its morphogenic plasticity upon external modulations. Using a variety of surgical and chemical treatments, we are able to induce phenotypic responses to the structure of the fin. In particular, fin cleft depth and the bifurcation of the bony rays are modulated by the surface area of the stump. To dissect the role of mechanotransduction in this process, we investigate the patterns of hydrodynamic forces acting on the surface of a zebrafish fin during regeneration by using particle tracking velocimetry on a range of biomimetic hydrofoils. This experimental approach enables us to quantitatively compare hydrodynamic stress distributions over flapping fins of varying sizes and shapes. As a result, viscous shear stress acting on the tip of the fin and the resulting internal tension are proposed as suitable signals for guiding the regulation of ray growth dynamics and branching pattern. Our findings suggest that mechanical forces are involved in the fine-tuning of the locomotory organ during fin morphogenesis.

scholarly journals Shear models and parametric analysis of the PVC geomembrane-cushion interface in a high rock-fill dam

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245245
Author(s):  
Yun-Feng Liu ◽  
Ke Gu ◽  
Yi-Ming Shu ◽  
Xian-Lei Zhang ◽  
Xin-Xin Liu ◽  
...  
Keyword(s):  
Shear Stress ◽  
Friction Coefficient ◽  
Three Dimensional ◽  
Viscous Friction ◽  
Hydraulic Pressure ◽  
Viscous Shear Stress ◽  
Box Counting ◽  
Viscous Shear ◽  
The Stability ◽  
Hysteresis Friction

As a type of flexible impermeable material, a PVC geomembrane must be cooperatively used with cushion materials. The contact interface between a PVC geomembrane and cushion easily loses stability. In this present paper, we analyzed the shear models and parameters of the interface to study the stability. Two different cushion materials were used: the common extrusion sidewall and non-fines concrete. To simulate real working conditions, flexible silicone cushions were added under the loading plates to simulate hydraulic pressure loading, and the loading effect of flexible silicone cushions was demonstrated by measuring the actual contact areas under different normal pressures between the geomembrane and cushion using the thin-film pressure sensor. According to elastomer shear stress, there are two main types of shear stress between the PVC geomembrane and the cushion: viscous shear stress and hysteresis shear stress. The viscous shear stress between the geomembrane and the cement grout was measured using a dry, smooth concrete sample, then the precise formula parameters of the viscous shear stress and viscous friction coefficient were obtained. The hysteresis shear stress between the geomembrane and the cushion was calculated by subtracting the viscous shear stress from the total shear stress. The formula parameters of the hysteresis shear stress and hysteresis friction coefficient were calculated. The three-dimensional box-counting dimensions of the cushion surface were calculated, and the formula parameters of the hysteresis friction were positively correlated with the three-dimensional box dimensions.

Fine-Tuning of Physicochemical Properties and Growth Dynamics of Mycelium-Based Materials

2020 ◽  
Vol 3 (2) ◽  
pp. 1044-1051 ◽  
Author(s):  
Maria Elena Antinori ◽  
Luca Ceseracciu ◽  
Giorgio Mancini ◽  
José A. Heredia-Guerrero ◽  
Athanassia Athanassiou
Keyword(s):  
Physicochemical Properties ◽  
Growth Dynamics ◽  
Fine Tuning

scholarly journals A growth model for water distribution networks with loops

2021 ◽  
Vol 477 (2255) ◽  
Author(s):  
Kashin Sugishita ◽  
Noha Abdel-Mottaleb ◽  
Qiong Zhang ◽  
Naoki Masuda
Keyword(s):  
Growth Model ◽  
Water Distribution ◽  
Growth Dynamics ◽  
Distribution Networks ◽  
Feedback Mechanism ◽  
Water Distribution Networks ◽  
Service Areas ◽  
The Difference ◽  
Positive Feedback Mechanism ◽  
Positive Correlations

Water distribution networks (WDNs) expand their service areas over time. These growth dynamics are poorly understood. One facet of WDNs is that they have loops in general, and closing loops may be a functionally important process for enhancing their robustness and efficiency. We propose a growth model for WDNs that generates networks with loops and is applicable to networks with multiple water sources. We apply the proposed model to four empirical WDNs to show that it produces networks whose structure is similar to that of the empirical WDNs. The comparison between the empirical and modelled WDNs suggests that the empirical WDNs may realize a reasonable balance between cost, efficiency and robustness in terms of the network structure. We also study the design of pipe diameters based on a biological positive feedback mechanism. Specifically, we apply a model inspired by Physarum polycephalum to find moderate positive correlations between the empirical and modelled pipe diameters. The difference between the empirical and modelled pipe diameters suggests that we may be able to improve the performance of WDNs by following organizing principles of biological flow networks.

scholarly journals Dullard-mediated Smad1/5/8 inhibition controls mouse cardiac neural crest cells condensation and outflow tract septation

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Jean-François Darrigrand ◽  
Mariana Valente ◽  
Glenda Comai ◽  
Pauline Martinez ◽  
Maxime Petit ◽  
...  
Keyword(s):  
Neural Crest ◽  
Developmental Process ◽  
Epithelial Mesenchymal Transition ◽  
Neural Crest Cells ◽  
Systemic Circulation ◽  
Outflow Tract ◽  
Fine Tuning ◽  
Mesenchymal Transition ◽  
Bmp Signalling ◽  
Gradient Amplitude

The establishment of separated pulmonary and systemic circulation in vertebrates, via cardiac outflow tract (OFT) septation, is a sensitive developmental process accounting for 10% of all congenital anomalies. Neural Crest Cells (NCC) colonising the heart condensate along the primitive endocardial tube and force its scission into two tubes. Here, we show that NCC aggregation progressively decreases along the OFT distal-proximal axis following a BMP signalling gradient. Dullard, a nuclear phosphatase, tunes the BMP gradient amplitude and prevents NCC premature condensation. Dullard maintains transcriptional programs providing NCC with mesenchymal traits. It attenuates the expression of the aggregation factor Sema3c and conversely promotes that of the epithelial-mesenchymal transition driver Twist1. Altogether, Dullard-mediated fine-tuning of BMP signalling ensures the timed and progressive zipper-like closure of the OFT by the NCC and prevents the formation of a heart carrying the congenital abnormalities defining the tetralogy of Fallot.

scholarly journals Winds and feedback from supermassive black holes accreting at low rates: hydrodynamical treatment

2020 ◽  
Vol 492 (2) ◽  
pp. 2553-2571 ◽  
Author(s):  
Ivan Almeida ◽  
Rodrigo Nemmen
Keyword(s):  
Black Holes ◽  
Initial Conditions ◽  
Rest Mass ◽  
Host Galaxy ◽  
Feedback Effects ◽  
Accretion Flows ◽  
Viscous Shear Stress ◽  
Viscous Shear ◽  
Thermally Driven ◽  
Hydrodynamical Simulations

ABSTRACT Outflows produced by a supermassive black hole (SMBH) can have important feedback effects in its host galaxy. An unresolved question is the nature and properties of winds from SMBHs accreting at low rates in low-luminosity active galactic nuclei (LLAGNs). We performed two-dimensional numerical, hydrodynamical simulations of radiatively inefficient accretion flows on to non-spinning black holes. We explored a diversity of initial conditions in terms of rotation curves and viscous shear stress prescriptions, and evolved our models for very long durations of up to 8 × 105GM/c3. Our models resulted in powerful subrelativistic, thermally driven winds originated from the corona of the accretion flow at distances 10−100 GM/c2 from the SMBH. The winds reached velocities of up to 0.01c with kinetic powers corresponding to $0.1\!-\!1 {\,{\rm per\, cent}}$ of the rest-mass energy associated with inflowing gas at large distances, in good agreement with models of the ‘radio mode’ of AGN feedback. The properties of our simulated outflows are in broad agreement with observations of winds in quiescent galaxies that host LLAGNs, which are capable of heating ambient gas and suppressing star formation.

On the radial structure of planetary rings

1984 ◽  
Vol 75 ◽  
pp. 431-437 ◽  
Author(s):  
A.W. Harris ◽  
W.R. Ward
Keyword(s):  
Shear Stress ◽  
Optical Depth ◽  
Orbital Velocity ◽  
Planetary Rings ◽  
Radial Gradient ◽  
Viscous Shear Stress ◽  
Viscous Shear ◽  
Radial Structure ◽  
Uniform Ring ◽  
Increasing Function

ABSTRACTA ring of particles in orbit about a planet experiences a viscous shear stress due to the radial gradient of orbital velocity. This stress tends to spread the ring with time. At low optical depth (τ ≲ 0.5), and again at high optical depth (τ ≳ 2), the shear stress is an increasing function of optical depth. In the intermediate range (0.5 ≲ x ≲ 2), stress may decrease with increasing τ, leading to a diffusive instability which will tend to break an Initially uniform ring into ringlets of high and low optical depths.

The Yield Stress for an Electrorheological Fluid in Squeeze

2001 ◽  
Author(s):  
Ali K. El Wahed ◽  
John L. Sproston
Keyword(s):  
Yield Stress ◽  
Electrorheological Fluid ◽  
Strain Characteristic ◽  
Viscous Shear Stress ◽  
Viscous Shear ◽  
Direction Dependence ◽  
Force Velocity ◽  
Displacement Force ◽  
Er Fluid

Abstract This paper is concerned with an experimental and theoretical determination of the rheological performance of an electrorhcological (ER) fluid when subjected to time-dependent applied loads. The experimental facility was built as a squeeze cell in which the fluid is sandwiched between two electrodes, one fixed and the other moving, which permits the instantaneous measurement of the mechanical and electrical responses of the fluid. The transient rheological characteristics of the fluid were assessed for various mechanical force levels and for constant voltage excitation of the fluid. Input and output stress levels across the fluid were monitored enabling the dynamic response of the fluid to be determined using a combination of displacement, force, velocity and acceleration transducers. The experimental results were compared with the results from a modified theoretical analysis, which employs a bi-viscous shear stress/shear strain characteristic of the electrically stressed fluid together with a fluid yield stress, which has a strain-direction dependence on the electrical field.

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