Discontinuous gas exchange in Madagascan hissing cockroaches is not a consequence of hysteresis around a fixed PCO2 threshold

It has been hypothesised that insects display discontinuous gas-exchange cycles (DGCs) due to hysteresis in their ventilatory control, where CO2-sensitive respiratory chemoreceptors respond to changes in hemolymph PCO2 only after some delay. If correct, DGCs would be a manifestation of an unstable feedback loop between chemoreceptors and ventilation causing PCO2 to oscillate around some fixed threshold value: PCO2 above this ventilatory threshold would stimulate excessive hyperventilation, driving PCO2 below the threshold and causing a subsequent apnoea. This hypothesis was tested by implanting micro-optodes into the hemocoel of Madagascar hissing cockroaches and measuring hemolymph PO2 and PCO2 simultaneously during continuous and discontinuous gas exchange. The mean hemolymph PCO2 of 1.9 kPa measured during continuous gas exchange was assumed to represent the threshold level stimulating ventilation, and this was compared with PCO2 levels recorded during DGCs elicited by decapitation. Cockroaches were also exposed to hypoxic (PO2 10 kPa) and hypercapnic (PCO2 2 kPa) gas mixtures to manipulate hemolymph PO2 and PCO2. Decapitated cockroaches maintained DGCs even when their hemolymph PCO2 was forced above or below the putative ∼2 kPa ventilation threshold, demonstrating that the characteristic oscillation between apnoea and gas exchange is not driven by a lag between changing hemolymph PCO2 and a PCO2 chemoreceptor with a fixed ventilatory threshold. However, it was observed that the gas exchange periods within the DGC were altered to enhance O2 uptake and CO2 release during hypoxia and hypercapnia exposure. This indicates that while respiratory chemoreceptors do modulate ventilatory activity in response to hemolymph gas levels, their role in initiating or terminating the gas exchange periods within the DGC remains unclear.

Heating-free, room-temperature operation of a radiofrequency-to-light signal transducer with a membrane oscillator and a built-in metasurface mirror

We present an electro-mechano-optical radiofrequency (rf)-to-light signal transducer robust against laser heating and thus operational at room temperature. A metal-free, low-loss metasurface mirror and an aluminum electrode made separately on a Si3N4 membrane oscillator comprise a chain of electro-mechanical and opto-mechanical systems, mediating electrical and optical signals through the (2,2)-mode characteristic oscillation. We demonstrate up-conversion of rf signals at 175.2 MHz by 6 orders of magnitude in frequency to an optical regime with the transfer efficiency of 2.3×10-9, also showing stable operation due to reduced laser heating of the mirror.

MOVEMENT OF CHARGED PARTICLES IN MAGNETIC AND NONUNIFORM STOCHASTIC ELECTRIC FIELDS

The equation of motion of charged plasma particles in a homogeneous magnetic field and in an inhomogeneous stochastic electric field with a characteristic oscillation frequency much lower than the electron cyclotron frequency and much higher than the ion cyclotron frequency is solved. The diffusion motion, as well as the drift of ions and guiding center of electrons, due to the inhomogeneity of the stochastic electric field, is considered. The obtained values of the diffusion coefficient and drift velocity are used in the Fokker-Planck equation to determine the stationary distribution of the plasma density due to the effect of an inhomogeneous stochastic field.

Semantic oscillations of supporting music of the ancient cult as the foundation of metamodernism elements in the works of contemporary opera directors

In recent decade, modernism as one of the varieties of post-postmodernism, draws interest of the researchers. It is suggested that modern culture has transgressed the situation of postmodernism, gravitating towards conceptual and semantic sustainability. As a language of self-description of the new era, the foundations of metamodernism are reflected in various forms of art. The opera house, overcoming the inertia of conservatism, perceives these trends, refracting them in a characteristic oscillation between the extreme semantic poles, which formed during the period of antiquity. The subject of this research is the correlation between the ancient musical heritage and metamodernistic trends in the modern opera theater. It is determined that translation of the principles of musical score of the ancient cult within the framework of the works of modern opera directors implies the characteristic to the supporting music of the cult forms of Ancient Greece and Rome oscillation between the poles of monophony – polyphony, instrumentality of accompaniment – a cappella, improvisational – preset of musical pieces. Paradigmatic assimilation of the fluctuations inherent to the cult of antiquity, as well as the absence of intentionality in their manifestations (which partially reflects the religious-ecstatic procedurality of art), largely determine the specific attributes of metamodernism, emphasized in the works of R. Castellucci, P. Sellars, R. Wilson, and D. Chernyakov.

Phase synchronization of fluid-fluid interfaces as hydrodynamically coupled oscillators

Hydrodynamic interactions play a role in synchronized motions of coupled oscillators in fluids, and understanding the mechanism will facilitate development of applications in fluid mechanics. For example, synchronization phenomenon in two-phase flow will benefit the design of future microfluidic devices, allowing spatiotemporal control of microdroplet generation without additional integration of control elements. In this work, utilizing a characteristic oscillation of adjacent interfaces between two immiscible fluids in a microfluidic platform, we discover that the system can act as a coupled oscillator, notably showing spontaneous in-phase synchronization of droplet breakup. With this observation of in-phase synchronization, the coupled droplet generator exhibits a complete set of modes of coupled oscillators, including out-of-phase synchronization and nonsynchronous modes. We present a theoretical model to elucidate how a negative feedback mechanism, tied to the distance between the interfaces, induces the in-phase synchronization. We also identify the criterion for the transition from in-phase to out-of-phase oscillations.

Asteroseismic masses of four evolved planet-hosting stars using SONG and TESS: resolving the retired A-star mass controversy

ABSTRACT The study of planet occurrence as a function of stellar mass is important for a better understanding of planet formation. Estimating stellar mass, especially in the red giant regime, is difficult. In particular, stellar masses of a sample of evolved planet-hosting stars based on spectroscopy and grid-based modelling have been put to question over the past decade with claims they were overestimated. Although efforts have been made in the past to reconcile this dispute using asteroseismology, results were inconclusive. In an attempt to resolve this controversy, we study four more evolved planet-hosting stars in this paper using asteroseismology, and we revisit previous results to make an informed study of the whole ensemble in a self-consistent way. For the four new stars, we measure their masses by locating their characteristic oscillation frequency, νmax, from their radial velocity time series observed by SONG. For two stars, we are also able to measure the large frequency separation, Δν, helped by extended SONG single-site and dual-site observations and new Transiting Exoplanet Survey Satellite observations. We establish the robustness of the νmax-only-based results by determining the stellar mass from Δν, and from both Δν and νmax. We then compare the seismic masses of the full ensemble of 16 stars with the spectroscopic masses from three different literature sources. We find an offset between the seismic and spectroscopic mass scales that is mass dependent, suggesting that the previously claimed overestimation of spectroscopic masses only affects stars more massive than about 1.6 M⊙.

Report on a characteristic oscillation about 38 mHz (26 s) in northeastern Japan following surface wave of the 2011 Tohoku megathrust earthquake

We try to detect an unidentified signal from the surface motion at northeastern Japan immediately after the 2011 Tohoku earthquake. A focused frequency range is 10–100 mHz (10–100 s). We find a peaky signal with frequency of about 38 mHz (26 s) based on the horizontal-to-vertical (H/V) spectral ratio using the high-rate GNSS data at 382 GEONET stations. We are not able to identify locality of the signal. The signal appears several minutes after the passing of surface wave fronts. The duration of the signal is about 2 min. Since the origin of the 38 mHz signal is unlikely to be local hydrologic tremors, tectonic tremors, or the tsunami, we speculate that the 38 mHz signal originates from a kind of a characteristic oscillation of Northeastern Japan triggered by the 2011 Tohoku earthquake. A normal-mode simulation implies that high-order radial overtones could create the signal with a spherically-layered velocity structure, however, the detailed mechanism of the signal still remains a mystery.

Non-Tidal Water Level Variability in Lianyungang Coastal Area

The non-tidal water level fluctuation at four locations in Lianyungang coastal area was analyzed by using tide data. Results show that the non-tidal water level fluctuation was associated with the spatial distribution. The combined effects of shoaling and attenuation due to the shape and bottom topography contribute to the spatial distribution of non-tidal water level fluctuation. Two characteristic oscillation periods of about 12 h and 24 h which highly coherent throughout the four stations were revealed. Analysis of the exciting mechanisms indicates that the variability was mainly generated by fluctuation in wind speed.