scholarly journals Quantified ensemble 3D surface features modeled as a window on centric diatom valve morphogenesis

2018 ◽  
Author(s):  
Janice L. Pappas

AbstractMorphological surface features are a record of genetic and developmental processes as well as environmental influences. The 3D geometric “terrain” of the surface consists of slopes via tangents, peaks and valleys via normals, smoothness of the transition between peaks and valleys, and point connections as flatness or curvature among all features. Such geometric quantities can be used to indicate morphological changes in valve formation over time. Quantified 3D surface features as geometric pattern ensembles may be representative of structural snapshots of the morphogenetic process.For diatoms, valve formation and pattern morphogenesis has been modeled using Turing-like and other algorithmic techniques to mimic the way in which diatoms exhibit the highly diverse patterns on their valve surfaces. How the created surface features are related to one another is not necessarily determined via such methods. With the diatom valve face structure of layered areolae, cribra, and other morphological characters, valve formation exhibits different combined geometries unfolding as 3D structural ensembles in particular spatial arrangements. Quantifying ensemble 3D surface geometries is attainable via models devised using parametric 3D equations and extracting surface features via partial derivatives for slopes, peaks and valleys, smoothness, and flatness as feature connectedness. Differences in ensemble 3D surface features may be used to assess structural differences among selected diatom genera as indicators of different valve formation sequences in surface generation and morphogenesis.

ETRI Journal ◽  
2012 ◽  
Vol 34 (1) ◽  
pp. 87-97 ◽  
Author(s):  
Myoung-Jong Noh ◽  
Woosug Cho ◽  
Ki In Bang

2016 ◽  
Vol 85 (4) ◽  
pp. 361-386 ◽  
Author(s):  
Jonas Keiler ◽  
Stefan Richter ◽  
Christian S. Wirkner

The Southern Australian crustacean species Lomis hirta (Lomisoidea: Lomisidae) is a representative of one of the three anomuran taxa which obtained their crab-like habitus independently from each other. This process, the evolutionary transformation into a crab-like form, is termed carcinization. To shed light on the morphological changes which took place during carcinization and to investigate structural dependence (coherence) between external and internal morphological characters, we studied L. hirta and representatives of its putatively most closely related taxa, Aegla cholchol (Aegloidea: Aeglidae) and Kiwa puravida (Chirostyloidea: Kiwaidae). External and internal anatomy was studied using microcomputertomography and computer-aided 3D reconstruction. A. cholchol and K. puravida belong to equally exceptional lineages: Aegla is endemic to South America and lives in freshwater habitats; Kiwa is a deep sea dweller associated to chemosynthetic bacteria found in methane seeps or hydrothermal vents. On the basis of recent cladistic analyses we reconstruct the anatomical ground pattern of the squat lobster-like last common ancestor of the three taxa and trace the morphological transformations that affected inner and outer morphology in the recent forms. Our results show, among other things, that the pleon in Lomis underwent drastic modifications in the context of carcinization, including a reduction of the muscular portion leaving more room for the hepatopancreas and gonads, and a narrowing of the pleonal ganglia which became shifted anteriorly into the cephalothorax and attached to the cephalothoracic ganglion. We interpret these anatomical changes in Lomis to have come about because of the loss of the caridoid escape reaction, which in turn was a direct consequence of the evolution of a strongly bent pleon as part of the crab-like habitus, and of a hidden lifestyle.


2008 ◽  
Vol 21 (4) ◽  
pp. 251
Author(s):  
Laurie G. Adams ◽  
Judy G. West ◽  
Kirsten J. Cowley

A revision of the Australian taxa of the genus Spergularia (Caryophyllaceae) on the basis of herbarium material, field studies and analysis of morphological characters necessitates realignment of some taxa and application of some neglected names, clarifying circumscription and understanding of the species of this genus. Eleven species are here recognised, with five considered indigenous, Spergularia nesophila and S. diandroides described as new and S. tasmanica transferred to Spergularia from Lepigonum. Fruits and seeds provide compelling diagnostic characters in this genus and are used in supplementary dichotomous and tabular diagnostic keys. Scanning electron micrographs (SEMs) illustrate key seed shape and surface features.


2016 ◽  
Vol 1136 ◽  
pp. 221-226
Author(s):  
Lan Zhan ◽  
Fei Hu Zhang ◽  
Chen Hui An ◽  
Zhi Peng Li

Ultra-precision fly cutting machines have long been the hardest one to compliant and induce great focus of researchers. In this paper, a surface topography model is proposed to predict the surface generation in an ultra-precision fly cutting machine. The building of surface topography model is based on the trace of the tool tip. With the 3D surface profile simulations of workpieces, several influencing factors of surface topography, especially the factors related to micro waviness error, are studied.


Silicon ◽  
2010 ◽  
Vol 4 (1) ◽  
pp. 39-49 ◽  
Author(s):  
H. J. Brasser ◽  
H. J. van der Strate ◽  
W. W. C. Gieskes ◽  
G. C. Krijger ◽  
E. G. Vrieling ◽  
...  

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