Transmethylation and control of pattern formation in hydrozoa

1986 ◽  
Vol 32 (1) ◽  
pp. 10-16 ◽  
Author(s):  
Stefan Berking
Keyword(s):  
Pattern Formation ◽  
And Control

scholarly journals A Review of Fluid Instabilities and Control Strategies with Applications in Microgravity

2021 ◽  
Author(s):  
Jeff Porter ◽  
Pablo Salgado Sánchez ◽  
Valentina Shevtsova ◽  
Viktar Yasnou
Keyword(s):  
Surface Tension ◽  
Pattern Formation ◽  
Thermal Energy ◽  
Growth Process ◽  
Control Strategies ◽  
Wave Instability ◽  
Highly Nonlinear ◽  
Fluid Instabilities ◽  
And Control ◽  
Gravity Surface

We give a brief review of several prominent fluid instabilities representing transitions driven by gravity, surface tension, thermal energy, and applied motion/acceleration. Strategies for controlling these instabilities, including their pattern formation properties, are discussed. The importance of gravity for many common fluid instabilities is emphasized and used to understand the sometimes dramatically different behavior of fluids in microgravity environments. This is illustrated in greater detail, using recent results, for the case of the frozen wave instability, which leads to large columnar structures in the absence of gravity. The development of these highly nonlinear states is often complex, but can be manipulated through an appropriate choice of forcing amplitude, container length and height, initial inclination of the surface, and other parameters affecting the nonlinear and inhomogeneous growth process. The increased opportunity for controlling fluids and their instabilities via small forcing or parameter changes in microgravity is notable.

Dissection of sexual organ ontogenesis: a genetic analysis of ovule development in Arabidopsis thaliana

Development ◽  
1997 ◽  
Vol 124 (7) ◽  
pp. 1367-1376 ◽  
Author(s):  
K. Schneitz ◽  
M. Hulskamp ◽  
S.D. Kopczak ◽  
R.E. Pruitt
Keyword(s):  
Arabidopsis Thaliana ◽  
Pattern Formation ◽  
Large Scale ◽  
Control Level ◽  
Three Dimensional ◽  
Flowering Plant ◽  
Ovule Development ◽  
Cellular Processes ◽  
Mature Ovule ◽  
And Control

Understanding organogenesis remains a major challenge in biology. Specification, initiation, pattern formation and cellular morphogenesis, have to be integrated to generate the final three-dimensional architecture of a multicellular organ. To tackle this problem we have chosen the ovules of the flowering plant Arabidopsis thaliana as a model system. In a first step towards a functional analysis of ovule development, we performed a large-scale genetic screen and isolated a number of sterile mutants with aberrant ovule development, We provide indirect genetic evidence for the existence of proximal-distal pattern formation in the Arabidopsis ovule primordium. The analysis of the mutants has identified genes that act at an intermediate regulatory level and control initiation of morphogenesis in response to proximal-distal patterning. A second group of genes functions at a subordinate control level and regulates general cellular processes of morphogenesis. A large group of male and female sterile mutants shows defects restricted to early or late gametogenesis. In addition, we propose that the mature ovule obtains its overall curved shape by at least three different processes that act in only one domain of the ovule.

The Design and Control of Catalytic Motors: Manipulating Colloids and Fluids with Self-Generated Forces

2006 ◽  
Vol 944 ◽  
Author(s):  
Timothy R. Kline ◽  
Jodi Iwata ◽  
Paul Lammert ◽  
Darrell Velegol ◽  
Thomas Mallouk ◽  
...  
Keyword(s):  
Pattern Formation ◽  
Electric Field ◽  
Electroosmotic Flow ◽  
Heterogeneous Catalysts ◽  
Chemical Methods ◽  
Additive Component ◽  
Catalytic Motors ◽  
And Control ◽  
A Current ◽  
Formation Design

ABSTRACTMicrofabrication was employed to pattern silver (Ag) on a gold (Au) surface. The two metals served as bimetallic heterogeneous catalysts for the heterogeneous decomposition of H2O2. Silver was the cathode, carrying out H2O2 reduction (to water) and gold the anode carrying out H2O2 oxidation (to oxygen). Both protons and electrons are created at the anode (as a part of the reaction) and migrate to the cathode (migration of ions is a current) where they are consumed. Thereby establishing an electric field (migration of ions obeys Ohm's law), which passively pumps fluids through electroosmosis. Electrophoresis also present as either an additive component to the electroosmotic flow or results in pattern formation (occurs at point where electroosmosis is equal and opposite to that of electrophoresis). Herein, the electrokinetic model is further tested and validated as chemical methods to tune the tracer behavior (convection to pattern formation), design of asymmetric patterns through microfabrication and attempts to indirectly measure the electric field were successful.

Manipulation, Stabilization, and Control of Pattern Formation Using Fourier Space Filtering

1998 ◽  
Vol 81 (8) ◽  
pp. 1614-1617 ◽  
Author(s):  
S. Juul Jensen ◽  
M. Schwab ◽  
C. Denz
Keyword(s):  
Pattern Formation ◽  
Fourier Space ◽  
And Control

scholarly journals Programmable pattern formation in cellular systems with local signaling

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Tiago Ramalho ◽  
Stephan Kremser ◽  
Hao Wu ◽  
Ulrich Gerland
Keyword(s):  
Pattern Formation ◽  
Cellular Systems ◽  
Target Pattern ◽  
Discrete State ◽  
Alternative Scheme ◽  
Control Schemes ◽  
Local Signaling ◽  
Update Rules ◽  
And Control ◽  
Logical Rules

AbstractComplex systems, ranging from developing embryos to systems of locally communicating agents, display an apparent capability of “programmable” pattern formation: They reproducibly form target patterns, but those targets can be readily changed. A distinguishing feature of such systems is that their subunits are capable of information processing. Here, we explore schemes for programmable pattern formation within a theoretical framework, in which subunits process local signals to update their discrete state following logical rules. We study systems with different update rules, topologies, and control schemes, assessing their capability of programmable pattern formation and their susceptibility to errors. Only a fraction permits local organizers to dictate any target pattern, by transcribing temporal patterns into spatial patterns, reminiscent of the principle underlying vertebrate somitogenesis. An alternative scheme employing variable rules cannot reach all patterns but is insensitive to the timing of organizer inputs. Our results establish a basis for designing synthetic systems and models of programmable pattern formation closer to real systems.

scholarly journals Dynamics of pattern formation and emergence of swarming in Caenorhabditis elegans

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Esin Demir ◽  
Y Ilker Yaman ◽  
Mustafa Basaran ◽  
Askin Kocabas
Keyword(s):  
Caenorhabditis Elegans ◽  
Pattern Formation ◽  
Chemical Cues ◽  
Sensory Information ◽  
Physical Factors ◽  
Behavioral Differences ◽  
Form Complex ◽  
Bacterial Accumulation ◽  
And Control ◽  
Food Bacteria

Many animals collectively form complex patterns to tackle environmental difficulties. Several biological and physical factors, such as animal motility, population densities, and chemical cues, play significant roles in this process. However, very little is known about how sensory information interplays with these factors and controls the dynamics of pattern formation. Here, we study the direct relation between oxygen sensing, pattern formation, and emergence of swarming in active Caenorhabditis elegans aggregates. We find that when thousands of animals gather on food, bacteria-mediated decrease in oxygen level slows down the animals and triggers motility-induced phase separation. Three coupled factors—bacterial accumulation, aerotaxis, and population density—act together and control the entire dynamics. Furthermore, we find that biofilm-forming bacterial lawns including Bacillus subtilis and Pseudomonas aeruginosa strongly alter the collective dynamics due to the limited diffusibility of bacteria. Additionally, our theoretical model captures behavioral differences resulting from genetic variations and oxygen sensitivity.

Control of Metal Alloy Oxidation with Electric Fields

1973 ◽  
Vol 31 ◽  
pp. 164-165
Author(s):  
R. R. Dils ◽  
P. S. Follansbee
Keyword(s):  
Electric Fields ◽  
Oxidation Process ◽  
Base Alloy ◽  
Oxide Surface ◽  
Platinum Electrodes ◽  
Insulating Layer ◽  
Iron Base Alloy ◽  
Alloy Oxidation ◽  
Aluminum Oxide Layer ◽  
And Control

Electric fields have been applied across oxides growing on a high temperature alloy and control of the oxidation of the material has been demonstrated. At present, three-fold increases in the oxidation rate have been measured in accelerating fields and the oxidation process has been completely stopped in a retarding field.The experiments have been conducted with an iron-base alloy, Pe 25Cr 5A1 0.1Y, although, in principle, any alloy capable of forming an adherent aluminum oxide layer during oxidation can be used. A specimen is polished and oxidized to produce a thin, uniform insulating layer on one surface. Three platinum electrodes are sputtered on the oxide surface and the specimen is reoxidized.

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