Cycle Oscillations Research Articles

Effects of ambient noise on quantum speed limit time and quantum discord dynamics of a double ‘gravitational cat state’ system

The exploration of the quantum nature of gravity has always been the focus of academic research. In this work, we consider a double ‘gravitational cat state’ quantum system consisting of a pair of massive particles coupled by gravitational interaction confined in their respective double potential Wells. Specifically, we model the double ‘gravitational cat state’ system as a two-qubit system, consider that the system is initially in the two-qubit Bell state, and study the influence of stable classical field and decayed field noise on the quantum speed limit time (QSLT) and trace distance discord (TDD) dynamics of the double ‘gravitational cat state’. The results show that the QSLT can be controlled by changing the parameters of the system and the environment, and the quantum state dynamics evolution of the system with massive particles can be accelerated. The quantum state evolution can be accelerated by increasing the gravitational coupling intensity between the two massive particles. The decay rate of the decaying field can also regulate the QSLT of the system to a certain extent, so as to accelerate the quantum state evolution, as shown in Fig. 8(a). Under the influence of decaying field noise, it is worth noting that the intensity of gravitational coupling affects the frequency of quantum discord oscillations in this two-particle system. The QSLT shows an oscillating trend with time, rapidly increases to a certain value in a short period of time, then begins to decline, and then oscillates until it reaches a stable value. That is to say, the evolution of quantum states goes through an oscillatory cycle of first deceleration and then acceleration until the evolution rate becomes stable after a certain period of time. At the same time, there are similar oscillations in the dynamics of quantum discord. Moreover, by comparing these two, it is found that the QSLT decreases in the process of the system's quantum discord increase. When the discord oscillation has regularity, QSLT tends to a certain value, and the quantum discord of the double ‘gravitational cat state’ system has a certain relationship with the QSLT, as shown in Fig. 8(b). In other words, quantum discord will affect the rate of quantum state evolution to some extent, and the increase of quantum discord between systems will be more conducive to the evolution of quantum states.

Kinetics and dynamics of atomic-layer dissolution on low-defect Ag.

Electrochemical metal dissolution reaction is a fundamental process in various critical technologies, including metal anode batteries and nanofabrication. However, experimentally revealing the kinetics and dynamics of active sites of metal dissolution reactions is challenging. Herein, we investigate metal dissolution on near-perfect single-crystal surfaces of Ag within regions of a few hundred nanometers isolated by scanning electrochemical cell microscopy (SECCM). Potential oscillation is observed under constant current conditions for dissolution. The one-to-one correspondence between the dissolution charge and the geometry of the dissolution pit from colocalized imaging allows ambiguous correlation, which suggests that each oscillation cycle corresponds to the dissolution of one atomic layer. The oscillation behavior is further explained in a kinetic model, which reveals that the oscillation comes from the dynamic evolution of the number of different active sites as the dissolution progresses on each atomic layer. In addition to the fundamental interest, the ability to observe layer-by-layer dissolution in electrochemical measurements suggests a potential pathway for developing electrochemical atomic layer etching for fabricating structures and devices with atomic precision.

Influence of sweep angle on leading edge vortex dynamics of a fully passive oscillating-plate hydrokinetic turbine prototype

The present work assesses the use of spanwise flow in enhancing the performance of the fully passive oscillating-plate hydrokinetic turbine prototype by relating the dynamics of the leading edge vortex (LEV) to the power extraction performance. Two-dimensional (2D) planar and three-dimensional (3D) tomographic particle image velocimetry were employed to obtain quantitative flow structure of oscillating-plates undergoing heave and pitch motion in uniform inflow at Reynolds number of 21 000. A plate with a 6° sweep angle and an unswept plate (control case) were considered in the present study. Dynamics of the LEV were investigated using the patterns of the phase-averaged vorticity during the oscillation cycle. The 3D vector fields provided insights into the spanwise variation of the vortical structure and the rate of deformation of the vortex, which was determined by calculating the deformation terms in the vorticity transport equations which are related to the stability of the vortex. The results show evidence of a delay in the shedding of the LEV and an increase in its stability in the case of the swept plate, compared to the control case, which in turn benefit the power extraction performance at high inflow velocities.

On Rapid Vibration Suppression by Nonlinear Energy Sink during First Half Cycle of Oscillation

On Rapid Vibration Suppression by Nonlinear Energy Sink during First Half Cycle of Oscillation

Slow Dephasing of Coherent Optical Phonons in Two-Dimensional Lead Organic Chalcogenides.

Hybrid organic-inorganic semiconductors with strong electron-phonon interactions provide a programmable platform for developing a variety of electronic, optoelectronic, and quantum materials by controlling these interactions. However, in current hybrid semiconductors such as halide perovskites, anharmonic vibrations with rapid dephasing hinder the ability to coherently manipulate phonons. Here, we report the observation of long-lived coherent phonons in lead organic chalcogenides (LOCs), a new family of hybrid two-dimensional semiconductors. These materials feature harmonic phonon dynamics despite distorted lattices, combining long phonon dephasing times with tunable semiconducting properties. A dephasing time -up to 75 ps at 10 K, with up to ∼500 cycles of phonon oscillation between scattering events, was observed, corresponding to a dimensionless harmonicity parameter that is more than an order of magnitude larger than that of halide perovskites. The phonon dephasing time is significantly influenced by anharmonicity and centrosymmetry, both of which can be tuned through the design of the organic ligands enabled by the direct bonding between the organic and inorganic motifs. This research opens new opportunities for the manipulation of electronic properties with coherent phonons in hybrid semiconductors.

Shift in Electrochemical Pathway Under Forced Periodic Operation of Potential Applied Due to Catalytic Resonance Effect

Sabatier's law is central to our understanding of catalysis. It states that the reactants will form reaction intermediates on the catalytic surface for a given catalytic reaction. Crucially, these intermediates must have an intermediate level of stability. If they are too stable, they will fail to decompose to form the product, and if they are too unstable, the catalyst will fail to activate the reaction1. The traditional strategy to design a catalyst for a reaction system is achieved by tuning the d-band filling of the catalyst (by making alloys, bimetallic, etc.) or by changing surface structure. Instead, this work demonstrates a constructive approach to shifting reaction pathways using the same catalyst. In the photo- and electrocatalysis, the shift in the reaction pathways (and selectivity) can also be achieved by operating the catalytic reactor using periodic modulation of one or multiple parameters around the steady state point2.This study considers the electrochemical oxidation of formic acid over a Pt catalyst. This reaction follows a triple pathway: direct, indirect, and formate3. The indirect pathway forms CO as an intermediate, which strongly interacts with the catalyst surface. To further oxidise CO, an OH species needs to be adsorbed to form CO2, which requires a potential above 0.8 V vs RHE. Therefore in a steady-state galvanostatic operation, the reaction shows self-oscillation within a specific current range3.This study uses a clean-electrolytic cell consisting of flame-annealed platinum wire as working and platinum mesh as a counter electrode with RHE as the reference electrode. The electrolytic cell is purged continuously with nitrogen, and gas is analysed using a gas analyser. The electrolyte consists of Suprapur 0.5 M H2SO4 and 0.2 M HCOOH. A sinusoidal voltage with a DC offset of 0.64 V vs RHE and amplitude of 0.26 V vs RHE was applied by varying frequency from 0 to 800 Hz. An enhancement in reaction rate by 1.94 times was observed at 800 Hz compared to steady-state operation at 0.9 V vs RHE. The I-V curve shows a qualitative enhancement towards the formate pathway compared to the indirect pathway above 600 Hz. The shift from indirect to formate pathway with a change in frequency above 600 Hz is further explained by the results from Electrochemical in situ Surface-enhanced attenuated total internal reflection infrared spectroscopy.Reference Chorkendorff, I. & Niemantsverdriet, J. W. Concepts of Modern Catalysis and Kinetics. Concepts Mod. Catal. Kinet. (2003). doi:10.1002/3527602658Ellwood, Th., Živković, L., Denissenko Petr, Abiev, R.Sh., Rebrov E.V., Menka Petkovska, Processes 2021, 9(11), 2046; /doi.org/10.3390/pr9112046Calderón-Cárdenas, A., Hartl, F. W., Gallas, J. A. C. & Varela, H. Modeling the triple-path electro-oxidation of formic acid on platinum: Cyclic voltammetry and oscillations. Catal. Today (2019). doi:10.1016/j.cattod.2019.04.054

Highly separated transitional shock-wave/boundary-layer interactions: A spatial modal study

At cruise altitudes, the Reynolds number may become sufficiently low to allow a laminar boundary layer to persist on the suction side of a transonic fan blade up to the shock-wave/boundary-layer interaction (SBLI). In such a transitional SBLI with sufficiently large shock-induced separation, a shock oscillation mechanism occurs, with the source at the upstream growth (until a critical length) and natural suppression (through shear layer instabilities) of the separation bubble. The oscillation cycle is characterized by a temporarily vanishing upstream laminar part of the separation bubble. The suppression of this laminar part is accompanied by downstream advection of turbulence and subsequent entrainment into the bulk separation bubble, affecting the reflected shock movement. In order to study the spatial behavior of the mechanism, particle image velocimetry of a highly separated transitional oblique SBLI at Mach 2.3 is conducted in the high speed aerodynamics laboratory of Delft University of Technology. Statistical quantities, including root mean square velocity fluctuations, phase averages, and spatial modes from proper orthogonal decomposition, are investigated. The entrainment strength varies depending on the phase of the oscillation, and the turbulent shear layer is not fully developed. The main growth and shrinking mode of the separation bubble were extracted, which affects the slip line region size and shock position. Secondary modes that affect the shear layer undulation and upstream effects were also extracted. The study provides quantitative analyses of an important shock oscillation type, with the focus on capturing the separation bubble size variation and upstream effects.

Periodic dynamics in viscous fingering

The displacement of a viscous liquid by air inside a Hele-Shaw channel is an archetype for nonlinear pattern-forming systems. Typically, bubbles or fingers of air propagate steadily at low values of the capillary number Ca = μ U * / σ , where μ is the viscosity of the liquid, U * is the speed of the bubble or finger and σ is the surface tension at the air–liquid interface. However, as the capillary number increases, the advancing interface can exhibit disordered pattern-forming dynamics. We demonstrate experimentally that a sustained, remote perturbation of the bubble tip can drive time-periodic dynamics. We exploit the propensity of a group of bubbles to propagate in steady spatial arrangements inside a Hele-Shaw channel with a centralized depth-reduction to apply a sustained pressure perturbation ahead of the bubble as it propagates. The oscillation cycle is initiated by the splitting of the bubble tip, via the Saffman–Taylor instability, which is promoted by the local flow-field conditions. The restoral of the bubble tip follows naturally because the system is driven by a fixed flow rate and the perturbed bubble is attracted to the weakly unstable, steadily propagating state that is set by the ratio of imposed viscous and capillary forces. The splitting and restoral mechanisms do not rely on the specific perturbation used in this study, suggesting a generic mechanism for periodic dynamics of propagating curved fronts subject to steady flow-field perturbations.

Experimental facility dedicated to detection and prediction of penstock fatigue induced by pressure oscillations

Abstract Hydroelectric powerplants play a vital role in the electricity production mix, especially during the ongoing energy transition towards renewable sources. However, they face operational challenges due to harmful stress loading of various components. Ensuring safe operation remains essential for people’s safety, electricity supply, and costs avoidance. The study focuses on penstocks and pipelines material damaging caused by fatigue, crack initiation and propagation. These critical components are often several decades old and expensive to refurbish or replace. Cycling loading, induced by pressure oscillations during start-stop or transient operations, accelerates material fatigue. Steel lining corrodes over time, and welds may contain original defects. To address this, a new testing facility that generates controlled cyclic pressure oscillations using the water hammer effect has been built. This specific closed-loop circuit allows accelerated fatigue testing of material probes, providing insights into crack initiation and propagation. The test rig operating principle is described while its 1D numerical model is introduced and validated with measurement data. The prediction of crack incipience and rupture of a tubular specimen with a pre-machined longitudinal weakening is in the end compared with the results of a fatigue test conducted on the test bench.

Dynamics of Sandy Shorelines and Their Response to Wave Climate Change in the East of Hainan Island, China

Beach erosion and shoreline dynamics are strongly affected by alterations in nearshore wave intensity and energy, especially in the context of global climate change. However, existing works do not thoroughly study the evolution of the sandy coasts of eastern Hainan Island, China, nor their responses to wave climate change driven by climate variability. This study focuses on the open sandy coast and assesses shoreline evolutionary dynamics in response to wave climate variability over a 30-year period from 1994 to 2023, using an open-source software toolkit that semi-automatically identify the shorelines (CoastSat v2.4) and reanalysis wave datasets (ERA5). The shorelines of the study area were extracted from CoastSat, and then tidal correction and outlier correction were performed for clearer shorelines. Combining the shoreline changes and wave conditions derived from ERA5, the dynamics of the shorelines and their response to wave climate change were further studied. The findings reveal that the average long-term shoreline change rate along the eastern coast of Hainan Island is 0.03 m/year, with 44.8% of transects experiencing erosion and 55.2% showing long-term accretion. And distinct evolutionary patterns emerge across different sections. Interannual variability is marked by alternating erosion and siltation cycles, while most sections of the coast experiences clear seasonal fluctuations, with accretion typically occurring during summer and erosion occurring in winter. El Niño–Southern Oscillation (ENSO) cycles drive changes in parameters including significant wave height, mean wave period, wave energy flux, and mean wave direction, leading to long-term changes in wave climate. The multi-scale behavior of the sandy shoreline responds distinctly to the ongoing changes in wave climate triggered by ENSO viability, with El Niño events typically resulting in accretion and La Niña periods causing erosion. Notably, mean wave direction is the metric most closely linked to changes in the shoreline among all the others. In conclusion, the interplay of escalating anthropogenic activities, natural processes, and climate change contributes to the long-term evolution of sandy shorelines. We believe this study can offer a scientific reference for erosion prevention and management strategies of sandy beaches, based on the analysis presented above.

Relaxation Oscillation, Homoclinic Orbit and Limit Cycles in a Piecewise Smooth Predator–Prey Model

Relaxation Oscillation, Homoclinic Orbit and Limit Cycles in a Piecewise Smooth Predator–Prey Model

A Detailed Study of Jupiter’s Great Red Spot over a 90-day Oscillation Cycle

Jupiter’s Great Red Spot (GRS) is known to exhibit oscillations in its westward drift with a 90-day period. The GRS was observed with the Hubble Space Telescope on eight dates over a single oscillation cycle in 2023 December to 2024 March to search for correlations in its physical characteristics over that time. Measured longitudinal positions are consistent with a 90-day oscillation in drift, but no corresponding oscillation is found in latitude. We find that the GRS size and shape also oscillate with a 90-day period, having a larger width and aspect ratio when it is at its slowest absolute drift (minimum date-to-date longitude change). The GRS’s UV and methane gas absorption-band brightness variations over this cycle were small, but the core exhibited a small increase in UV brightness in phase with the width oscillation; it is brightest when the GRS is largest. The high-velocity red collar also exhibited color changes, but out of phase with the other oscillations. Maximum interior velocities over the cycle were about 20 m s−1 larger than minimum velocities, slightly larger than the mean uncertainty of 13 m s−1, but velocity variability did not follow a simple sinusoidal pattern as did other parameters such as longitude width or drift. Relative vorticity values were compared with aspect ratios and show that the GRS does not currently follow the Kida relation.

Nonlinear three-dimensional modeling for encapsulated microbubble dynamics subject to ultrasound

Encapsulated microbubbles (EMBs) stabilized by thin coatings have been used as contrast agents for ultrasound sonography as well as having been demonstrated as a promising new technology for targeted drug delivery. The dynamics of EMBs is three-dimensional (3D) because EMBs within micro-vessels inevitably interact with boundaries, but the theoretical and numerical studies are limited to spherical, weakly non-spherical, and/or axisymmetric EMBs. Here, we have developed physical, mathematical, and numerical models for nonlinear 3D EMB dynamics. The liquid flow is evaluated using the boundary integral method. The EMB coating is modeled as a thin viscoelastic shell including stretching, bending, and shear effects and simulated using the finite element method. These models are coupled through the kinematic and dynamic boundary conditions at the interface. The model is in good agreement with the Hoff equation for spherical EMBs and the asymptotic theory for weakly non-spherical deformation of EMBs. Using this model, a numerical study for EMB dynamics near a rigid boundary subject to an ultrasonic wave is performed. The migration, non-spherical oscillation, resonant oscillation, and jetting of EMBs are displayed and analyzed systematically. If the ultrasound wave is strong, a high-speed liquid jet forms at the final stage of the collapse, orientated between the directions of the wave and toward the wall. The EMB jet is weaker and slower and has less momentum, as the non-spherical deformation of the coating and the jetting are suppressed by the viscoelastic property of the coating. If the ultrasound is not strong, the EMB remains spherical for many cycles of oscillation but the EMB undergoes resonant oscillation and becomes significantly non-spherical after several oscillation cycles, when the wave frequency is equal to its natural frequency. The numerical capability has the potential to be developed for the optimization of sonography or drug delivery.

Features of subseasonal concurrent variations between subtropical and polar front jets and their association with temperature anomalies in China

Subseasonal variability of atmospheric circulation in mid-high latitudes is highly correlated to the upper-level jet streams, acting as a major contributor to the global or regional persistent climate anomalies. In this study, the features of subseasonal concurrent variations (SCVs) between East Asian Polar Front Jet (EAPJ) and Subtropical Jet (EASJ), and corresponding atmospheric circulation and temperature anomalies in China are investigated by using the observational data and NCEP/NCAR reanalysis datasets. Results show that the main variability modes of the winter upper-level wind fields on subseasonal time scales are characterized by the meridional shift in opposite directions and out-of-phase variations in the intensity of the EASJ and EAPJ. These concurrent variations between the two jets have a significant oscillation cycle with a period of 10–25 days. Accompanied by the location (intensity) SCV of the two jets, the mid-latitude circulation systems show significant zonal shifts (local intensity changes), resulting in alternations of the atmospheric circulation between zonal and meridional types. The typical meridional circulation is characterized by a strong East Asian trough and its upstream strong high-pressure ridges. Meanwhile, gradient force between Siberian high and the Aleutian low is anomalously strong. As a result, the SCVs between two jets can cause widespread and persistent low temperature anomalies over China, usually lasting more than three days. In the case of the location SCV of the two jets, the low temperature anomalies concentrate in northern China, particularly in north of 40°N. In the case of the intensity SCV of the two jets, the low temperature anomalies occur in most parts of China, notably in south of 40°N. These results are helpful to improve the prediction of atmospheric circulation and temperature anomalies in East Asia during winter.

Application of the Point Defect Model to the Oscillatory Anodic Oxidation of Illuminated n-Type Silicon in the Presence of Fluoride Ions Using Electrochemical Impedance Spectroscopy

This work aims to provide insight into the oscillations occurring during the anodic electrooxidation of Si in fluoride-containing electrolytes using electrochemical impedance spectroscopy (EIS). The EIS measurements were conducted within less than a tenth of the oscillation periods allowing changes in the electrical properties of the silicon/oxide/electrolyte interfaces to be monitored during an oscillatory cycle. Application of the power law model to the experimental data revealed a significant change in resistivity at the oxide/semiconductor interface while the properties at the oxide/electrolyte interface remained constant and the oxide layer varied only by about 1 nm around an average value of about 4.9 nm. The application of the point defect model to the semiconductor/oxide/F−-containing electrolyte interface suggests that the oscillations are linked to the time delay between the production of oxygen vacancies at the Si/oxide interface and their consumption at the oxide/electrolyte interface.

Age-related differences in how the shape of alpha and beta oscillations change during reaction time tasks

While the shape of cortical oscillations is increasingly recognised to be physiologically and functionally informative, its relevance to the aging motor system has not been established. We therefore examined the shape of alpha and beta band oscillations recorded at rest, as well as during performance of simple and go/no-go reaction time tasks, in 33 young (23.3 ± 2.9 years, 27 females) and 27 older (60.0 ± 5.2 years, 23 females) adults. The shape of individual oscillatory cycles was characterised using a recently developed pipeline involving empirical mode decomposition, before being decomposed into waveform motifs using principal component analysis. This revealed four principal components that were uniquely influenced by task and/or age. These described specific dimensions of shape and tended to be modulated during the reaction phase of each task. Our results suggest that although oscillation shape is task-dependent, the nature of this effect is altered by advancing age, possibly reflecting alterations in cortical activity. These outcomes demonstrate the utility of this approach for understanding the neurophysiological effects of ageing.

Linear and nonlinear interfacial rheology of responsive microgels at the oil-water interface

Microgelation can significantly enhance the interfacial activity of polysaccharide and the ability to stabilize emulsion, but the interfacial behaviour of microgels and the intrinsic mechanism of stabilizing emulsion is not fully understood. In this study, chitosan microgels (h-CSMs) with uniform size were successfully prepared by electrostatic crosslinking hydrophobically modified chitosan (h-CS) with sodium phytate (SP) using microfluidic technique. The microfluidic conditions for fabricating of h-CSM were optimized: the mass ratio of h-CS: SP = 5: 1 with h-CS concentration of 0.5 mg/ml, and the pressure ratio of Ph-CS (Pa):PSP (Pa) = 1600:1000. The prepared h-CSMs were pH-responsive, with a swollen state at pH 5 and a shrunken state at pH 3 and 7. Further, the interfacial adsorption kinetics, and the interfacial rheology particularly the nonlinear interfacial rheology were systematically studied. The instantaneous Si-factor was proposed to describe the nonlinear responses of the microgel interface during an individual dilatational oscillation cycle. The results showed that microgelation significantly improved the interfacial ability of chitosan molecules at the oil-water interface. The h-CSM interface exhibited strain-softening response during extension and strain-hardening response during compression. The interface formed by h-CSMs under the swollen state had higher viscoelastic modulus, lower degree of nonlinearity and higher emulsifying capacity compared to that formed under the shrinking state. Low ionic strength significantly increased the viscoelastic modulus and reduced the nonlinearity and enhanced emulsifying capacity of the h-CSM interface, whereas high ionic strength disrupted the interaction between the h-CSMs and increased the nonlinear of the h-CSM interface due to too strong electrostatic screening effect.

PyFMLab: Open-source software for atomic force microscopy microrheology data analysis

Background Atomic force microscopy (AFM) is one of the main techniques used to characterize the mechanical properties of soft biological samples and biomaterials at the nanoscale. Despite efforts made by the AFM community to promote open-source data analysis tools, standardization continues to be a significant concern in a field that requires common analysis procedures. AFM-based mechanical measurements involve applying a controlled force to the sample and measure the resulting deformation in the so-called force-distance curves. These may include simple approach and retract or oscillatory cycles at various frequencies (microrheology). To extract quantitative parameters, such as the elastic modulus, from these measurements, AFM measurements are processed using data analysis software. Although open tools exist and allow obtaining the mechanical properties of the sample, most of them only include standard elastic models and do not allow the processing of microrheology data. In this work, we have developed an open-source software package (called PyFMLab, as of python force microscopy laboratory) capable of determining the viscoelastic properties of samples from both conventional force-distance curves and microrheology measurements. Methods PyFMLab has been written in Python, which provides an accessible syntax and sufficient computational efficiency. The software features were divided into separate, self-contained libraries to enhance code organization and modularity and to improve readability, maintainability, testability, and reusability. To validate PyFMLab, two AFM datasets, one composed of simple force curves and another including oscillatory measurements, were collected on HeLa cells. Results The viscoelastic parameters obtained on the two datasets analysed using PyFMLab were validated against data processing proprietary software and against validated MATLAB routines developed before obtaining equivalent results. Conclusions Its open-source nature and versatility makes PyFMLab an open-source solution that paves the way for standardized viscoelastic characterization of biological samples from both force-distance curves and microrheology measurements.

Modeling non-stationarity in extreme rainfall data and implications for climate adaptation: A case study from southern highlands region of Tanzania

The Southern Highlands region of Tanzania has witnessed an increased frequency of severe flash floods. This study examines rainfall data of four stations (Iringa, Mbeya, Rukwa, and Ruvuma) spanning 30 years (1991–2020) to investigate drivers of extreme rainfall and non-stationarity behavior. The Generalized Extreme Value (GEV) model, commonly used in hydrological studies, assumes constant distribution parameters, which may not be true due to climate variability, potentially leading to bias in extreme quantile estimation. Recent studies have introduced a technique for constructing non-stationary Intensity-Duration-Frequency (IDF) rainfall curves. The method incorporates trends in the parameters of the GEV distribution, only using time as a covariate. However, uncertainty exists about whether time is the most suitable covariate, highlighting the need to explore all potential covariates for modeling non-stationarity. The aim of this study is to assess the influence of other time-varying covariates on extreme daily rainfall events, considering seasonality and climate change in the rainfall data. Specifically, five processes (i.e., local temperature changes (LTC), urbanization, annual Global Temperature Anomaly (GTA), the Indian Ocean Dipole (IOD), and the El Niño-Southern Oscillation (ENSO) cycle) were studied as drivers of extreme rainfall events. Sixty two non-stationary GEV models are developed based on these covariates and their combinations, alongside two non-stationary GEV models using the time covariate to capture the seasonality of the unimodal rainfall in the region, and one stationary GEV model (S0). With the use of corrected Akaike Information Criterion (AICc), the best model for each duration (i.e., 1-, 3-, and 5-days) of rainfall series is chosen. Results indicate that local processes (i.e., LTC and urbanization) are the optimal covariates for 1 day-duration rainfall, while global processes (i.e, IOD, ENSO cycle, and GTA) are identified as the most suitable covariates for 3, and 5 day-duration rainfall across all stations. The identified best non-stationary model (with their best covariates) are then used to develop non-stationary rainfall IDF curves for all stations. According to the analysis of non-stationary extreme values, the return periods of extreme rainfall events concluded a notable decrease in comparison to the stationary approach. The study also revealed strong correlations between global climate indices (ENSO, IOD, GTA) and long-duration extreme rainfall in Tanzania’s Southern Highlands. Local factors like Urbanization and temperature changes also show significant associations with 1-day duration events. These findings emphasize the need for integrated climate forecasting to inform effective adaptation strategies. Finally, the study addresses associated uncertainties in our predictions of forthcoming extreme rainfall events through rigorous analysis. The study demonstrated that return levels for extreme rainfall events exhibit a rising trend with increasing return period, indicating heightened intensity over longer time spans, whereas, a relative uncertainty analysis illustrate escalating uncertainty with increasing return periods, emphasizing challenges in long-term prediction.

Electrical integrity and week-long oscillation in fungal mycelia

The electrical potential of the mycelia of a cord-forming wood decay fungus, Pholiota brunnescens, was monitored for over 100 days on a plain agar plate during the colonization onto a wood bait. Causality analyses of the electrical potential at different locations of the mycelium revealed a clear and stable causal relationship with the directional flow of the electrical potential from the hyphae at the bait location to other parts of the mycelium. However, this causality disappeared after 60 days of incubation, coinciding with the onset of slow electrical oscillation at the bait location, which occurred over one week per oscillation cycle. We speculated that the hyphae that initially colonized the bait may act as a temporary activity center, which generates electrical signals to other parts of the mycelium, thereby facilitating the colonization of the entire mycelial body to the bait. The week-long electrical oscillation represents the longest oscillation period ever recorded in fungi and warrants further investigation to elucidate its function and stability in response to environmental stimuli.