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Hgf/c-Met signaling supports migration of cells with CEC phenotype

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The “bag breakup” fragmentation is the dominant mechanism for spume droplet production in high winds, which substantially affects the ocean–atmosphere exchange processes. The amount of droplets ejected from the surface, as well as their typical sizes, is prescribed by the surface wind velocity and fetch. The corresponding empirical correlations were obtained only for the limited parameters of the laboratory environment. The applicability range can be extended through the construction of a theoretical model that describes the initiation of the bag-breakup fragmentation, estimates the fragmenting liquid volume prescribing the droplet sizes, and determines the dependence on the wind parameters. This paper presents such a model. First, we conducted linear stability analysis of small-scale disturbances at the water surface under a high wind; this showed that the small-scale ripples (about 1 cm) propagating against the wind in the surface wind drift following the reference frame grew fast due to the Kelvin–Helmholtz instability, when the wind friction velocity exceeded the threshold of about 1 m s−1. Given the weak dispersion, the nonlinear stage of evolution was addressed using the Riemann simple wave equation modified to describe the increasing disturbances. The analytical solution for the equation suggested the scaling of the volume of liquid undergoing the bag-breakup fragmentation and its dependence on in agreement with the laboratory data. Using the scaling, we calculated the statistics of the bag-breakup fragmentation based on the lognormal size distribution of the fragmenting objects. Significance Statement The “bag breakup” fragmentation is the dominant mechanism for generating spray in hurricane winds. The parameters of spray droplets substantially affect the exchange processes between the ocean and the atmosphere and, thereby, the development of sea storms. The rapid process of spray generation can only be studied in laboratory environments using sophisticated experimental techniques. To apply the laboratory data to field conditions, we need a theoretical model that describes the threshold for fragmentation initiation, the fragmenting liquid volume, which scales the size and number of spray droplets, their dependence on wind parameters, etc. In the present work, we suggest a simple analytical model of the bag-breakup initiation, verify it in the laboratory experiment, and suggest the statistical description of the fragmentation events.

The book about Louis Henri de Nicolay, a German-speaking poet from Strasbourg, is much more than a reconstruction of the biography of a “German in Russia”. The multi-author book edited by Rodolphe Baudin and Alexandra Veselova reveals the mechanisms underlying the functioning of intellectual ties between Alsace and Russia. Also, it demonstrates the “exemplary” and unique features of the personal history of a graduate of the University of Strasbourg, who became a tutor of the future Emperor Paul I and then president of the Academy of Sciences in St Petersburg. The authors show the life trajectory of Nicolay in the broad context of the tripartite cultural transfer between France, Germany, and Russia and of the “circulation of knowledge and people” in Europe as a whole. The multifaceted image of the Strasbourg intellectual is recreated through the analysis of his epistolary and poetic heritage, sources on the history of Mon Repos Park (Nicolay's estate near Vyborg), and the study of the mythologisation of his personality in Russian and Soviet culture. The publication of sources of personal origin makes the book more valuable. They are letters of Louis Henri de Nicolay, introduced into scholarly circulation and extensively commented on by the authors of the edition. This research appears to be a landmark in the historiography of intellectual connections in Europe during the Age of Enlightenment.

Lagrangian stochastic models (LSM) are widely used to model the dispersion of sea spray droplets injected from the water surface into the marine atmospheric boundary layer (MABL) and for evaluation of the spray impact on the exchange fluxes between the atmosphere and the ocean. While moving through the MABL the droplets pass through the region of high gradients of air velocity, temperature and humidity occurring in the vicinity of the air-water interface. In this case, the applicability of LSMs constructed under the assumption of weakly inhomogeneous flows is questionable. In this work, we develop a Lagrangian stochastic model taking into account the strongly inhomogeneous structure of the airflow in MABL and, in particular, the anisotropy of turbulence dissipation rate. The model constants and the diffusion matrix coefficients are calibrated by comparison of the LSM prediction for the profiles of droplet concentration and the exchange fluxes of sensible and latent heat against the results of direct numerical simulation (DNS) of turbulent, droplet-laden airflow over a waved water surface.

A series of experiments was carried out on the Thermostratified Wind Wave Tank of IAP RAS, to study the processes of secondary generation of spray due to the fall of the droplets onto a rough surface. The general scheme of the experiments was similar to [1]. The range of equivalent wind speed from U10 is from 21 to 34 m/s. Initially, high-speed filming with shadow visualization of the rough surface from above was performed, followed by detection, marking and calculating the number of events during image processing using special programs. It has been demonstrated that the number of phenomena of falling drops into water per unit time per unit area, leading to the formation of spray, significantly exceeds the similar values for previously studied mechanisms of spray generation: liquid ligaments fragmentation type, bubbles rupture and bag-breakup fragmentation type. Further, detailed studies of this phenomenon were carried out with a higher resolution filming. Two main scenarios of this event: with the formation of a “crown” at large angles of drop incidence, and the so-called "jet" at small angles were identified by analogy with [2]. The number droplets, size and velocity distributions were obtained for different wind speeds. These results can be used to design a spray generation function due to this phenomenon.Investigations were supported by Russian Science Foundation project 21-19-00755 (carrying out experiments), Russian Foundation Basic Research project 21-55-52005 (data processing), work of A.A. Kandaurov was partially supported by the President's grant for young scientists МК-5503.2021.1.5.Troitskaya, A. Kandaurov, O. Ermakova, D. Kozlov, D. Sergeev, and S. Zilitinkevich, The ‘Bag Breakup’ Spume Droplet Generation Mechanism at High Winds. Part I: Spray Generation Function, J. Phys. Oceanogr., vol. 48, no. 9, pp. 2167–2188, 2018. V. Gielen, P. Sleutel, J. Benschop, M. Riepen, V. Voronina, C. W. Visser, D. Lohse, J. H. Snoeijer, M. Versluis, andH. Gelderblom, Oblique drop impact onto a deep liquid pool, Phys. Rev. Fluids, vol. 2, pp. 083602, 2017.

The work is concerned with the study of the breaking surface wave impact on the scattered radar signal in laboratory conditions using optical methods for analyzing the state of the water surface.The experiments were carried out on the reconstructed TSWiWaT wind wave flume of the IAP RAS. The channel is 12 m long, the channel cross-section varies from 0.7 x 0.7 m at the entrance to 0.7 x 0.9 m in the working section at a distance of 9 m. The airflow speed on the axis is 3-35 m/s, which corresponds to the values of the wind speed U10 of 11-50 m/s.At the beginning of the channel, a wavemaker was installed, operating in a pulsed mode and generating a train of three long waves every 15 seconds. In front of the area under study, an inclined plate was installed under the water, simulating shallow water and stimulating the breaking of waves in the zone of optical and radar measurements. In parallel, wind waves were generated. Due to the design features of the experimental setup, the distance from the beginning of the channel to the inclined plate in the case of optical measurements was 884 cm, and for radar measurements - 781 cm.Radar measurements were carried out using a Doppler scatterometer operating at a wavelength of 3.2 cm, with the ability to simultaneously receive two direct and two cross-polarizations (VV, HH, VH, HV). The dimensions of the observation window on the water surface varied depending on the selected incidence angles (30, 40, 50 degrees). Optical measurements were carried out independently of radar measurements using three cameras with a shooting frequency of 50 Hz. Using a specially developed algorithm based on threshold processing of the image brightness, the time dependences of the fraction of breakers on the area of the investigated water surface during the passage of a train of three waves were calculated. Due to the different configuration of the experiments, the data of radar and optical measurements are separated in time, their synchronization was performed using correlation analysis. Comparison of the data made it possible to find that, on cross-polarization, the received power monotonically increases with an increase in the fraction of breakers, while on direct polarization, the change in power remains within the values observed during collapses of wind waves. Further comparison of the values of the radar cross-section of the water surface and the relative area of the wave breaking will make it possible to determine the influence of the breaking on the formation of the scattered signal.This work was supported by the Russian Science Foundation (RSF) project No. 21-17-00214.

Within the framework of this study, the dynamics and thermodynamics of individual spherical droplets of various sizes injected into the air flow during their interaction with a marine atmospheric boundary layer were calculated within Lagrangian stochastic model (LSM). The fields of velocity, humidity, and temperature are presented as a superposition of the average component determined from the approximations of the Monin-Obukhov similarity theory and the fluctuation component. Turbulent fluctuations are calculated using a stochastic model based on the Langevin equation, containing the matrix of inverse relaxation times of turbulent fluctuations of the Lagrangian particles velocity. To define whether isotropic matrix or anisotropic one should be selected and also to determine the value of Kolmogorov constant the calculations within LSM were compared with the results of direct numerical simulation of the inertial particles in the atmospheric boundary layer above surface waves. It was shown that the isotropic diffusion matrix underestimates the turbulent diffusion of particles, so anisotropic one was selected.It was assumed that the injection of droplets into the air flow was carried out through two main mechanisms - fragmentation according to the "parachute" type (Troitskaya et al., Scientific Reports, 2017) and the rupture of floating bubbles. In the calculations, new modifications of the spray generation functions were used, taking into account the dependence of the number of generation events on the number of spray, obtained within the laboratory experiments done by the authors in their previous studies.The processes of heat-moisture exchange of droplets with a turbulent air flow, taking into account phase transitions, are described using the equations of droplet microphysics (Pruppatcher and Klett (1978)). Heat, moisture and momentum fluxes are calculated on the basis of averaging over the horizontal coordinate of the equations of thermoaerodynamics. These equations include volumetric sources of momentum, heat and moisture to take into account the effect of droplets on the temperature and humidity of atmospheric air, which are obtained by averaging the solution to the equations of microphysics of droplets. When calculating the profiles of average temperature and humidity, gradient hypotheses of closure with the coefficients of turbulent diffusion coefficients of heat and humidity were used.The work is supported by the Russian Science Foundation (RSF) project № 19-17-00209Troitskaya, Y., Kandaurov, A., Ermakova, O., Kozlov D., Sergeev D., Zilitinkevich S. Bag-breakup fragmentation as the dominant mechanism of sea-spray production in high winds. Sci Rep 7, 1614 (2017). https://doi.org/10.1038/s41598-017-01673-9. Prupatcher H.R., Klett J.D. Microphysics of Clouds and Precipitation. Dordrecht: D. Riedel. 1978, 714 p. https://doi.org/10.1007/978-94-009-9905-3.

We investigated the effect of weak combined magnetic field (CMF) on stem cell proliferation and regeneration of the planarian Schmidtea mediterranea. CMF parameters were set in accordance with Valery Lednev's theory of magnetic parametric resonance. It was shown that CMF with an amplitude of 74 μT and a frequency of 30 Hz accelerated the growth of the planarian head blastema by 25%. Alterations of the frequency in range from 27 to 33 Hz led to a complete disappearance of the effect. A further decrease in the CMF frequency inhibited regeneration. The maximum inhibition (24%) was observed at a frequency of 16 Hz. A further decrease in the CMF frequency (down to 13 Hz) led to disappearance of the described effect. Regeneration rate changes under the CMF are influenced by alterations in stem cell mitotic activity, which in turn depends on the wound-induced gene expression level. Thus, the CMF, preset in accordance to the Lednev's theory, can specifically influence the expression of regeneration-related genes and regeneration itself, what can find biomedical applications.