scholarly journals Quantitative Characterization of Stress Concentration in the Presence of Closely Spaced Hard Inclusions in Two-Dimensional Linear Elasticity

2018 ◽  
Vol 232 (1) ◽  
pp. 121-196 ◽  
Author(s):  
Hyeonbae Kang ◽  
Sanghyeon Yu
Development ◽  
2020 ◽  
Vol 147 (17) ◽  
pp. dev192237
Author(s):  
Scott M. Zeng ◽  
Emily K. W. Lo ◽  
Bryna J. Hazelton ◽  
Miguel F. Morales ◽  
Keiko U. Torii

ABSTRACTStomata are epidermal valves that facilitate gas exchange between plants and their environment. Stomatal patterning is regulated by the EPIDERMAL PATTERING FACTOR (EPF) family of secreted peptides: EPF1 enforces stomatal spacing, whereas EPIDERMAL PATTERNING FACTOR-LIKE9 (EPFL9), also known as Stomagen, promotes stomatal development. It remains unknown, however, how far these signaling peptides act. Utilizing Cre-lox recombination-based mosaic sectors that overexpress either EPF1 or Stomagen in Arabidopsis cotyledons, we reveal a range within the epidermis and across the cell layers in which these peptides influence patterns. To determine their effective ranges quantitatively, we developed a computational pipeline, SPACE (stomata patterning autocorrelation on epidermis), that describes probabilistic two-dimensional stomatal distributions based upon spatial autocorrelation statistics used in astrophysics. The SPACE analysis shows that, whereas both peptides act locally, the inhibitor EPF1 exerts longer range effects than the activator Stomagen. Furthermore, local perturbation of stomatal development has little influence on global two-dimensional stomatal patterning. Our findings conclusively demonstrate the nature and extent of EPF peptides as non-cell autonomous local signals and provide a means for quantitative characterization of complex spatial patterns in development.This article has an associated ‘The people behind the papers’ interview.


Author(s):  
Ervin E. Underwood

Stereology is the study of the three-dimensional structure of materials from two-dimensional sections or projections. By suitable statistical measurements on the test plane or projection plane, and by utilizing the basic equations of stereology, the true three-dimensional quantities can be calculated. Such attributes of the structure as points P, lines L, surfaces S, volumes V, numbers N, as well as spacings, sizes, curvatures, etc. can be obtained without a priori assumptions.In this review, the basic relationships of quantitative stereology are summarized, both for opaque and transparent materials. Thus the image to be analyzed may derive from a photograph of a metallic polished surface or from an electron transmission micrograph obtained from a biological slice or replica. The complete quantitative characterization of the microstructure involves data obtained from both reflected images and transmitted (or projected) images. We will discuss the relationships applicable to each type of image, then show their interrelationships.


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