Oscillatory response of cellular tissues has been observed in multiple embryogenetic developmental stages. The source of these oscillations has been attributed to imbalance of instabilities in the chemo-mechanical signalling and delayed cell activity. Although the relation of these oscillations with further drastic tissue deformation remains uncertain, it is apparent that intracellular remodelling events seem to drive the viscoelastic properties and the measured pulsatile deformations.We here resort to a viscoelastic model that is based on a variable restlength of the cell. We include a delay between the measured elastic strain and the evolution of the rest-length which dynamically adapts to the cell strain. This law is not only able to reproduce the relaxation phenomena observed in embryonic tissues in vitro and in vivo, but also to give rise to oscillatory cell responses. We analyse the stability of the resulting oscillations on minimal systems with two cells, and also on planar or out of plane deformation modes of monolayers. We conclude that in all cases, the stability decreases with an increasing delay or with the ability to adapt in a faster manner.

We report measurements of muon flux over the sky of the city of Bogotá at 4∘35′56′′ north latitude, 74∘04′51′′ west longitude, and an altitude of 2657 m above sea level, carried out with a hodoscope composed of four stations of plastic scintillators located equidistant over a distance of 4.8 m. Measurements were taken at different zenith (θ) angles within the range 1.5∘≤θ≤90∘, the muon flux data is statistically consistent with a cos2θ dependence, with a χ2 per degree of freedom near unity. If instead, we fit to a cosnθ we obtain n=2.145±0.046 with a lower χ2 per degree of freedom. Integrating the muon flux distribution as a function of the zenith angle over the solid angle of the upper Earth’s hemisphere allows an estimation of the atmospheric vertical muon rate at the altitude and latitude of Bogota obtaining a value of 255.1±5.8m−2s−1. This estimate is consistent with an independent direct measurement of the vertical muon flux with all detectors stacked horizontally. These measurements play a key role in the further development of detectors, aimed to perform muon imaging of Monserrate Hill, located in Bogotá, where the detectors will be placed at similar locations to those used in the present study.

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