Although the importance of cellular forces to a wide range of embryogenesis and disease processes is widely recognized, measuring these forces is challenging, especially in three dimensions. Here, we introduce CellFIT-3D, a force inference technique that allows tension maps for three-dimensional cellular systems to be estimated from image stacks. Like its predecessors, video force microscopy and CellFIT, this cell mechanics technique assumes boundary-specific interfacial tensions to be the primary drivers, and it constructs force-balance equations based on triple junction (TJ) dihedral angles. The technique involves image processing, segmenting of cells, grouping of cell outlines, calculation of dihedral planes, averaging along three-dimensional TJs, and matrix equation assembly and solution. The equations tend to be strongly overdetermined, allowing indistinct TJs to be ignored and solution error estimates to be determined. Application to clean and noisy synthetic data generated using Surface Evolver gave tension errors of 1.6-7%, and analyses of eight-cell murine embryos gave estimated errors smaller than the 10% uncertainty of companion aspiration experiments. Other possible areas of application include morphogenesis, cancer metastasis and tissue engineering.This article is part of the themed issue 'Systems morphodynamics: understanding the development of tissue hardware'.
A novel air-filled E-plane rectangular waveguide (RWG) to substrate integrated waveguide (SIW) transition, which is suitable for Ka-band large-scale antenna arrays, is presented. The power is coupled between the RWG and SIW through two slots: one etched on the SIW ground plane and the other cut through metallic RWG narrow side wall (E-plane). A back-to-back transition is designed, fabricated, assembled, and tested. Measured results show a good agreement with the simulated ones. An SIW attenuation loss ≤0.33 dB/1 cm and a transition return loss better than 10 dB have been experimentally obtained over the band 28.30-30.8 GHz.
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