Live Cancer Cell Classification Based on Quantitative Phase Spatial Fluctuations and Deep Learning With a Small Training Set

We present an analysis method that can automatically classify live cancer cells from cell lines based on a small data set of quantitative phase imaging data without cell staining. The method includes spatial image analysis to extract the cell phase spatial fluctuation map, derived from the quantitative phase map of the cell measured without cell labeling, thus without prior knowledge on the biomarker. The spatial fluctuations are indicative of the cell stiffness, where cancer cells change their stiffness as cancer progresses. In this paper, the quantitative phase spatial fluctuations are used as the basis for a deep-learning classifier for evaluating the cell metastatic potential. The spatial fluctuation analysis performed on the quantitative phase profiles before inputting them to the neural network was proven to increase the classification results in comparison to inputting the quantitative phase profiles directly, as done so far. We classified between primary and metastatic cancer cells and obtained 92.5% accuracy, in spite of using a small training set, demonstrating the method potential for objective automatic clinical diagnosis of cancer cells in vitro.

Stress-weighted spatial averaging of random fields in geotechnical risk assessment

Effects of spatial fluctuations of soil parameters are considered in a new context – considering variability of soil parameters in conjunction with non-uniform stress fields, which can locally amplify (or suppress) subsoil inhomogeneities. In this way, several design situations for the Coulomb frictional material with random tan(φ(x)) reveal a reduction of variance, which is less significant than for the standard volume averaging. When looking for an ‘effective’ random variable [tan(φ)]a – that is, a random variable, which is equivalent to the random field tan(φ( x )) – the Vanmarcke averaging by simple volume integrals is insufficient; it systematically overestimates effects of variance reduction, thus causing potentially unsafe situations. The new proposed approach is coherent, formally defined and more realistic.

Calcium fluctuations drive morphological patterning at the onset of Hydra morphogenesis

Morphogenesis in animal development involves significant morphological transitions leading to the emerging body plan of a mature animal. Understanding how the collective physical processes drive robust morphological patterning requires a coarse-grained description of the dynamics and the characterization of the underlying fields. Here I show that calcium spatial fluctuations serve as an integrator field of the electrical-mechanical processes of morphogenesis in whole-body Hydra regeneration and drive the morphological dynamics. We utilize external electric fields to control the developmental process and study a critical transition in morphogenesis, from the initial spheroidal shape of the tissue to an elongated cylindrical shape defining the body plan of a mature animal. Morphogenesis paused under external voltage is associated with a significant increase of the calcium activity compared with the activity supporting normal development. The enhanced calcium activity is characterized by intensified spatial fluctuations, extended spatial correlations across the tissue and faster temporal fluctuations. In contrast, the normal morphogenesis process is characterized by relatively moderate calcium fluctuation activity and restrained spatial correlations. Long-range communication however, is essential for development. Blocking gap-junctions halts morphogenesis by suppressing the long-range electrical communication, severely reducing the overall calcium activity and enhancing its localization in the tissue. Normal calcium activity is resumed following the wash of the blocker drug, leading to a morphological transition characterizing a normal regeneration process and the emergence of a mature animal. Our methodology of controlling morphogenesis by a physical electric field allows us to gain a global statistical view of the dynamics. It shows that the normalized calcium spatial fluctuations exhibit a universal shape distribution, across tissue samples and conditions, suggesting the existence of a global constrain over these fluctuations. Studying the correlations in space and time of the calcium fluctuation field at the onset of morphogenesis opens a new vista on this process and paints a picture of development analogous to a dynamical phase transition.

Productivitatea fitoplanctonului fluviului Nistru și lacului de acumulare Dubăsari în condițiile impactului factorilor naturali și antropici

The article presents the results on the study of productivity of phytoplankton and destruction of organic matter in the Dniester River and Dubasari reservoir in 2020. The values of primary production in Dniester River varied during the vegetation period within the limits of 0.81-3.79 gO2/m-2 24h, and of the destruction of organic substances between 3.9-45.12 gO2/m-2 24h. In the Dubasari reservoir, the primary production of phytoplankton was significantly influenced by the hydrochemical and hydrobiological state of the waters from the middle sector of the Dniester River and varied within 0.572.82 gO2/m-2 24h. The values of destruction of organic substances exceeded the values of primary production and registering values between 2.1623.66 gO2/m-2 24h. The seasonal and spatial fluctuations of phytoplankton primary production values in Dniester river and Dubasari reservoir are followed by successions of phytoplankton structure, changes in nutrient concentrations and oscillations of water transparency values. The values of destruction of organic substances were higher than primary production values. The A/R ratio reflect a negative balance of formation of organic substances in Dniester River and Dubasari reservoir.

Nonlinear Wave Transformation in Coastal Zone: Free and Bound Waves

The nonlinear transformation of waves in the coastal zone over the sloping bottom is considered on the base of field, laboratory, and numerical experiments by methods of spectral and wavelet analyses. The nonlinearity leads to substantial changes of wave shape during its propagation to the shore. Since these changes occur rapidly, the wave movement is non-periodical in space, and the application of linear theory concepts of wavenumber or wavelength results in some paradoxical phenomena. When analyzing the spatial evolution of waves in the frequency domain, the effect of periodic energy exchange and changes in the phase shift between the first and second wave harmonics are observed. When considering the wavenumber domain, the free and bound waves of both the first and second harmonics with constant in space amplitudes appear, and all spatial fluctuations of the wave parameters are caused by interference of these four harmonics. Practically important consequences such as the wave energy spatial fluctuations and of anomalous dispersion of the second harmonic are shown and discussed.

A random-walk-based epidemiological model

Random walkers on a two-dimensional square lattice are used to explore the spatio-temporal growth of an epidemic. We have found that a simple random-walk system generates non-trivial dynamics compared with traditional well-mixed models. Phase diagrams characterizing the long-term behaviors of the epidemics are calculated numerically. The functional dependence of the basic reproductive number $$R_{0}$$ R 0 on the model’s defining parameters reveals the role of spatial fluctuations and leads to a novel expression for $$R_{0}$$ R 0 . Special attention is given to simulations of inter-regional transmission of the contagion. The scaling of the epidemic with respect to space and time scales is studied in detail in the critical region, which is shown to be compatible with the directed-percolation universality class.

Energy fluctuations in recorder pipes during transient sound attacks and steady state sound

The evaluation of temporal and spatial fluctuations of energy using compressible fluid analysis is proposed as an effective method to clarify the fundamental mechanism of the self-sustained oscilla-tions in a actual recorder. The main factors of the self-sustained oscillations are investigated in more detail by evaluating not only the steady state of the sound where the flow field and the sound field are completely coupled, but also the characteristics at the attack transient of the sound before the coupling is established. By analyzing the large energy fluctuations that occur just below the edge of the labium in the attack transient, it was shown that this phenomenon may be one of the main causes of the self-sustained oscillations. And the characteristics of the energy fluctuations and sound power generation during the steady state of the sound are discussed. It was also focused on the energy variations in another region that is near the exit of the windway.

Prevalence of Alaria alata mesocercariae in wild boars from Brandenburg, Germany

Since 2002, Alaria (A.) alata mesocercariae (AM) have been found during routine Trichinella inspection of wild boars in many European countries. To date, human infection with AM through consumption of undercooked or raw AM infested wild boar meat cannot be excluded. In Germany, data on the parasite’s prevalence in wild boars are scarce. To better understand temporal and spatial fluctuations of this parasite, this study investigated the prevalence of AM in wild boars in the German federal state of Brandenburg during three hunting seasons from 2017 to 2020. In total, 28.3% (100/354, 95% CI: 23.3–33.3%) of all wild boars sampled in eight counties of Brandenburg were tested positive for AM by Alaria alata mesocercariae migration technique (AMT). AM were detected in wild boars from seven different counties. Samples from one county (Havelland) tested completely negative for AM (0/16). Prevalences of the seven AM positive counties of Brandenburg ranged from 11.5 (3/26, 95% CI: 2.5–30.1%) in Märkisch-Oderland to 64.1% (25/39, 95% CI: 47.2–78.8%) in Uckermark. An association between sex and A. alata positivity could not be determined. A statistically significant increase in frequency of older AM positive wild boars was observed (p = 0.001). For a nationwide assessment of the prevalence of A. alata in wild boars and the risk for consumers of ingesting viable AM by consumption of raw or undercooked AM infested wild boar meat, further long-term studies in different regions of Germany are needed.

Pervasive diffusion of climate signals recorded in ice-vein ionic impurities

A theory of vein impurity transport conceived two decades ago predicts that signals in the bulk concentration of soluble ions in ice migrate under a temperature gradient. If valid, it would mean that some palaeoclimatic signals deep in ice cores (signals from vein impurities as opposed to matrix or grain-boundary impurities) suffer displacements that upset their dating and alignment with other proxies. We revisit the vein physical interactions to find that a strong diffusion acts on such signals. It arises because the Gibbs–Thomson effect, which the original theory neglected, perturbs the impurity concentration of the vein water wherever the bulk impurity concentration carries a signal. Thus, any migrating vein signals will not survive into deep ice where their displacement matters, and the palaeoclimatic concern posed by the original theory no longer stands. Simulations with signal peaks introduced in shallow ice at the GRIP and EPICA Dome C ice-core sites, ignoring spatial fluctuations of the ice grain size, confirm that rapid damping and broadening eradicates the peaks by two-thirds way down the ice column. Artificially reducing the solute diffusivity in water (to mimic partially connected veins) by 103 times or more is necessary for signals to penetrate into the lowest several hundred metres with minimal amplitude loss. Simulations incorporating grain-size fluctuations on the decimetre scale show that these can cause the formation of new, non-migrating solute peaks. The deep solute peaks observed in ice cores can only be explained by widespread vein disconnection or a dominance of matrix or grain-boundary impurities at depth (including their recent transfer to veins) or signal formation induced by grain-size fluctuations; in all cases, the deep peaks would not have displaced far. Disentangling the different signal contributions – from veins, the ice matrix, grain boundaries, and grain-size fluctuations – will aid robust reconstruction from ion records.