Pattern formation of coupled spiral waves in bilayer systems: Rich dynamics and high-frequency dominance

2011 ◽  
Vol 84 (5) ◽  
Author(s):  
Haichun Nie ◽  
Jihua Gao ◽  
Meng Zhan
Keyword(s):  
Pattern Formation ◽  
High Frequency ◽  
Spiral Waves

Axial organization of the regenerating limb: asymmetrical behaviour following skin transplantation

Development ◽  
1982 ◽  
Vol 70 (1) ◽  
pp. 197-213
Author(s):  
M. Maden ◽  
K. Mustafa
Keyword(s):  
Pattern Formation ◽  
Lower Limb ◽  
High Frequency ◽  
Skin Grafting ◽  
Good Frequency ◽  
Skin Transplantation ◽  
Serial Sectioning ◽  
Whole Mount ◽  
Ventral Skin ◽  
Anterior Posterior

An extensive series of skin grafting operations has been performed to investigate axial organization in the regenerating axolotl limb. Semicircular cuffs of skin from either anterior, posterior, dorsal or ventral surfaces were exchanged between right and left limbs thereby creating limbs with double anterior, double posterior, double dorsal or double ventral skin, all with normal internal tissues. Both fore and hindlimbs were used at both upper and lower limb levels. Following amputation through the grafted region the resulting regenerates were analysed both by whole-mount cartilage staining to observe the pattern of digits and by serial sectioning to observe the pattern of muscles. There were clear asymmetries in ability to produce duplications - posterior to anterior grafts resulted in a consistently high frequency of digital duplications, whereas anterior to posterior grafts produced very few. Similarly, dorsal to ventral grafts resulted in a good frequency of muscle duplications, whereas ventral to dorsal grafts did not. Such asymmetrical behaviour is not predicted by most models involving local cell:cell interactions and the significance of the results for theories of pattern formation is discussed.

SPATIOTEMPORAL PATTERN FORMATION ON THE ACE16k CNN CHIP

2006 ◽  
Vol 16 (05) ◽  
pp. 1537-1546 ◽  
Author(s):  
M. E. YALÇIN ◽  
J.A.K. SUYKENS
Keyword(s):  
Pattern Formation ◽  
Spiral Waves ◽  
Spatiotemporal Pattern ◽  
Spatiotemporal Pattern Formation ◽  
External Sources ◽  
Fixed State ◽  
Internal Sources ◽  
The Waves

In this paper, we report on pattern formation occurring on the ACE16k CNN chip. The CNN chip can be programmed with a cloning template in order to generate spiral waves and autowaves. The waves diffract from internal sources which cannot be relocated on the network. However, by using initial and/or input images, sources (external sources) can be located at any place on the network. Furthermore a competition between autowaves generated by external and internal sources is observed. Propagation of autowaves on the inhomogeneous CNN array, formed by the fixed-state map, is presented.

Pattern formation of spiral waves in an inhomogeneous medium with small-world connections

2002 ◽  
Vol 65 (5) ◽  
Author(s):  
Daihai He ◽  
Gang Hu ◽  
Meng Zhan ◽  
Wei Ren ◽  
Zhuo Gao
Keyword(s):  
Pattern Formation ◽  
Inhomogeneous Medium ◽  
Small World ◽  
Spiral Waves

Parasites and Pattern Formation

1999 ◽  
Vol 54 (2) ◽  
pp. 146-152 ◽  
Author(s):  
J. Ackermann ◽  
T. Kirner
Keyword(s):  
Pattern Formation ◽  
Flow Reactor ◽  
Spiral Waves ◽  
Cooperative Interaction ◽  
Biological Information ◽  
Parameter Region ◽  
Parasitic Species ◽  
Model Complex ◽  
Complex Patterns ◽  
The Stability

Abstract Biological information is coded in replicating molecules. To maintain a given amount of in-formation a cooperative interaction between these molecules is essential. The main problem for the stability of a system of prebiotic replicators are emerging parasites. Stabilization against such parasites is possible if space is introduced in the model. Complex patterns like spiral waves and self-replicating spot patterns have been shown to stabilize such systems. Stability of replicating systems, however, occurs only in parameter regions were such complex patterns occur. We show that parasites are able to push such systems into a parameter region were life is possible. To demonstrate this influence of parasites on such systems, we introduce a parasitic species in the Gray-Scott model. The growing concentration of parasites will kill the system, and the cooperative Gray-Scott system will be diluted out in a well mixed flow reactor. While considering space, in the model stabilizing pattern formation in a narrow parameter region is possible. We demonstrate that the concentration of the parasitic species is able to push the system into a region were stabilizing patterns emerge.

Eliminating spiral waves pinned to an anatomical obstacle in cardiac myocytes by high-frequency stimuli

2008 ◽  
Vol 78 (6) ◽  
Author(s):  
Akihiro Isomura ◽  
Marcel Hörning ◽  
Konstantin Agladze ◽  
Kenichi Yoshikawa
Keyword(s):  
Cardiac Myocytes ◽  
High Frequency ◽  
Spiral Waves

The Microstructure of Steatite (Protoenstatite)

1985 ◽  
Vol 43 ◽  
pp. 236-237
Author(s):  
W. E. Lee ◽  
A. H. Heuer
Keyword(s):  
High Frequency ◽  
Glass Ceramics ◽  
Magnesium Silicate ◽  
Beam Current ◽  
Glassy Matrix ◽  
Angle Of Incidence ◽  
X Ray ◽  
Mechanical And Electrical Properties ◽  
Argon Ions ◽  
High Temperature Polymorph

IntroductionTraditional steatite ceramics, made by firing (vitrifying) hydrous magnesium silicate, have long been used as insulators for high frequency applications due to their excellent mechanical and electrical properties. Early x-ray and optical analysis of steatites showed that they were composed largely of protoenstatite (MgSiO3) in a glassy matrix. Recent studies of enstatite-containing glass ceramics have revived interest in the polymorphism of enstatite. Three polymorphs exist, two with orthorhombic and one with monoclinic symmetry (ortho, proto and clino enstatite, respectively). Steatite ceramics are of particular interest a they contain the normally unstable high-temperature polymorph, protoenstatite.Experimental3mm diameter discs cut from steatite rods (∼10” long and 0.5” dia.) were ground, polished, dimpled, and ion-thinned to electron transparency using 6KV Argon ions at a beam current of 1 x 10-3 A and a 12° angle of incidence. The discs were coated with carbon prior to TEM examination to minimize charging effects.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

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