The overshoot and phenotypic equilibrium in characterizing cancer dynamics of reversible phenotypic plasticity.

The paradigm of phenotypic plasticity indicates reversible relations of different cancer cell phenotypes, which extends the cellular hierarchy proposed by the classical cancer stem cell (CSC) theory. Since it is still questionable if the phenotypic plasticity is a crucial improvement to the hierarchical model or just a minor extension to it, it is worthwhile to explore the dynamic behavior characterizing the reversible phenotypic plasticity. In this study we compare the hierarchical model and the reversible model in predicting the cell-state dynamics observed in biological experiments. Our results show that the hierarchical model shows significant disadvantages over the reversible model in describing both long-term stability (phenotypic equilibrium) and short-term transient dynamics (overshoot) in cancer cell populations. In a very specific case in which the total growth of population due to each cell type is identical, the hierarchical model predicts neither phenotypic equilibrium nor overshoot, whereas the reversible model succeeds in predicting both of them. Even though the performance of the hierarchical model can be improved by relaxing the specific assumption, its prediction to the phenotypic equilibrium strongly depends on a precondition that may be unrealistic in biological experiments. Moreover, it still does not show as rich dynamics as the reversible model in capturing the overshoots of both CSCs and non-CSCs. By comparison, it is more likely for the reversible model to correctly predict the stability of the phenotypic mixture and various types of overshoot behavior.

Design and performance analysis of a mid-infrared broadband thermally tunable metamaterial absorption device based on the phase-change effect.

We propose a structurally simple, innovative, and multifunctional mid-infrared broadband thermally tunable metamaterial absorption device. The absorption device consists of a three-layer structure, from bottom to top: Ti substrate, SiO2 dielectric layer, and patterned VO2 layer. Through temperature control, the average absorption intensity of the absorption device can vary between 0.08 and 0.94. The absorption device's absorption mechanism is rooted in the thermal phase-change characteristics exhibited by the topologically patterned VO2. When the temperature is below 340 K, VO2 is in a dielectric state, resulting in near-total reflection performance in the mid-infrared range. When the temperature is above 340 K, VO2 undergoes a dielectric-to-metal transition, enabling the absorption device to achieve an average absorption rate of 94.12% in the ultra-wideband range of 6.26 µm-20.96 µm in the mid-infrared. This absorption range completely covers the atmospheric window wavelengths of 8 µm-14 µm, demonstrating high practical value. We explain the working mechanism of the absorption device from the perspective of the electromagnetic field. Subsequently, we study the variations in the absorption curve of the absorption device at different temperatures of VO2 and use the changes in the electric field at the same wavelength under different temperatures to explain the variations in absorption. Compared to previous work, our structure has only three layers in a single unit, making it easy to process and produce. Additionally, the absorption device's operating bandwidth and average absorption rate in the mid-infrared range have been significantly improved. Furthermore, the absorption device exhibits substantial incident angle tolerance and polarization insensitivity. We believe that this design has broad application potential in future optothermal conversion, infrared stealth, and thermal radiation.

Age-Related Differences in the Effects of Masker Cuing on Releasing Chinese Speech From Informational Masking.

The aims of the present study were to examine whether familiarity with a masker improves word recognition in speech masking situations and whether there are age-related differences in the effects of masker cuing. Thirty-two older listeners (range = 59-74; mean age = 66.41 years) with high-frequency hearing loss and 32 younger normal-hearing listeners (range = 21-28; mean age = 23.73) participated in this study, all of whom spoke Chinese as their first language. Two experiments were conducted and 16 younger and 16 older listeners were used in each experiment. The masking speech with different content from target speech with syntactically correct but semantically meaningless was a continuous recording of meaningless Chinese sentences spoken by two talkers. The masker level was adjusted to produce signal-to-masker ratios of -12, -8, -4, and 0 dB for the younger participants and -8, -4, 0, and 4 dB for the older participants. Under masker-priming conditions, a priming sentence, spoken by the masker talkers, was presented in quiet three times before a target sentence was presented together with a masker sentence 4 s later. In Experiment 1, using same-sentence masker-priming (identical to the masker sentence), the masker-priming improved the identification of the target sentence for both age groups compared to when no priming was provided. However, the amount of masking release was less in the older adults than in the younger adults. In Experiment 2, two kinds of primes were considered: same-sentence masker-priming, and different-sentence masker-priming (different from the masker sentence in content for each keyword). The results of Experiment 2 showed that both kinds of primes improved the identification of the targets for both age groups. However, the release from speech masking in both priming conditions was less in the older adults than in the younger adults, and the release from speech masking in both age groups was greater with same-sentence masker-priming than with different-sentence masker-priming. These results suggest that both the voice and content cues of a masker could be used to release target speech from maskers in noisy listening conditions. Furthermore, there was an age-related decline in masker-priming-induced release from speech masking.

Improvement of signal-to-noise ratio in parallel neuron arrays with spatially nearest neighbor correlated noise.

We theoretically investigate the signal-to-noise ratio (SNR) of a parallel array of leaky integrate-and-fire (LIF) neurons that receives a weak periodic signal and uses spatially nearest neighbor correlated noise. By using linear response theory, we derive the analytic expression of the SNR. The results show that the amplitude of internal noise can be increased up to an optimal value, which corresponds to a maximum SNR. Given the existence of spatially nearest neighbor correlated noise in the neural ensemble, the SNR gain of the collective ensemble response can exceed unity, especially for a negative correlation. This nonlinear collective phenomenon of SNR gain amplification may be related to the array stochastic resonance. In addition, we show that the SNR can be improved by varying the number of neurons, frequency, and amplitude of the weak periodic signal. We expect that this investigation will be useful for both controlling the collective response of neurons and enhancing weak signal transmission.

Dynamics and robustness of the cardiac progenitor cell induced pluripotent stem cell network during cell phenotypes transition.

Robustness is a fundamental characteristic of biological systems since all living systems need to adapt to internal or external perturbations, unpredictable environments, stochastic events and unreliable components, and so on. A long-term challenge in systems biology is to reveal the origin of robustness underlying molecular regulator network. In this study, a simple Boolean model is used to investigate the global dynamic properties and robustness of cardiac progenitor cell (CPC) induced pluripotent stem cell network that governs reprogramming and directed differentiation process. It is demonstrated that two major attractors correspond to source and target cell phenotypes, respectively, and two dominating attracting trajectories characterise the biological pathways between two major cell phenotypes. In particular, the experimentally observed transition between different cell phenotypes can be reproduced and explained theoretically. Furthermore, the robustness of major attractors and trajectories is largely maintained with respect to small perturbations to the network. Taken together, the CPC-induced pluripotent stem cell network is extremely robustly designed for their functions.