Time Behavior Research Articles

Simultaneous spatiotemporal transcriptomics and microscopy of Bacillus subtilis swarm development reveal cooperation across generations.

Development of microbial communities is a complex multiscale phenomenon with wide-ranging biomedical and ecological implications. How biological and physical processes determine emergent spatial structures in microbial communities remains poorly understood due to a lack of simultaneous measurements of gene expression and cellular behaviour in space and time. Here we combined live-cell microscopy with a robotic arm for spatiotemporal sampling, which enabled us to simultaneously acquire phenotypic imaging data and spatiotemporal transcriptomes during Bacillus subtilis swarm development. Quantitative characterization of the spatiotemporal gene expression patterns revealed correlations with cellular and collective properties, and phenotypic subpopulations. By integrating these data with spatiotemporal metabolome measurements, we discovered a spatiotemporal cross-feeding mechanism fuelling swarm development: during their migration, earlier generations deposit metabolites which are consumed by later generations that swarm across the same location. These results highlight the importance of spatiotemporal effects during the emergence of phenotypic subpopulations and their interactions in bacterial communities.

Nonlinear enhanced dissipation in viscous Burgers type equations II

In this follow up but self contained paper, we focus on the viscous Burgers equation. There, using the Hopf-Cole transformation, we compute the long time behavior of solutions for some classes of infinite mass initial datas. We show that an enhanced dissipation effect occurs generically, that is the decay rate in time is better than if we considered instead the heat equations for the same inital value. We also show the existence of a kind of global attractor per class.

Global strong solutions of three-dimensional heat conducting incompressible magnetohydrodynamic equations with vacuum

This paper is devoted to studying global existence and large time behavior of strong solutions of the three-dimensional heat conducting incompressible magnetohydrodynamic flows with initial vacuum and a vacuum far field. Under the scaling invariant quantity (1+‖ρ0‖∞)2(‖ρ0u0‖22+‖b0‖22)(‖∇u0‖22+‖∇b0‖22) is suitably small, the global well-posedness of strong solution to the Cauchy problem is proved. Here, the explicit dependence on the initial norms is given and the smallness depends only on the known parameters in the system. This implies that the global well-posedness result is also valid for some large initial data. Furthermore, the algebraic decay rates of the global solution are obtained.

Gaussian quantum entanglement in curved spacetime

The influence of Hawking radiation on quantum entanglement for bimodal Gaussian states near a Schwarzschild black hole is investigated. It is shown that for a thermal squeezed state of a bimodal bosonic system the Hawking radiation reduces and even can destroy the entanglement between the mode of a Kruskal observer Alice and the mode of Bob, who is an accelerated observer hovering outside the event horizon of black hole. By contrary, the Hawking radiation increases and even can generate quantum entanglement between Bob and anti-Bob, who is a hypothetical observer inside event horizon. We show that in both these scenarios the competition between the contrary influences produced by Hawking temperature, squeezing and field frequency, may favour the preservation of the quantum entanglement. We investigate also the influence of the thermal environment on the behaviour in time of the entanglement between the considered observers and show that the entanglement is destroyed in a finite time for both considered bipartite scenarios of observers Alice and Bob, and respectively Bob and anti-Bob, for non-zero values of the temperature of the thermal environment, i.e. the phenomenon of entanglement sudden death takes place. For a zero temperature of the thermal bath the initial existing entanglement is decreasing over time, but it keeps for all finite times a non-zero value and the logarithmic negativity tends to zero only in the limit of infinite time.

Chinese economic behavior in times of covid-19. A new leading economic indicator based on Google trends

Since December 2019 we have been living with a virus called SARS-CoV-2 which has led to health policies being given prevalence over economic ones, causing serious consequences with regard to China's economic growth. For this purpose, we have built a Real Time Leading Economic Indicator based on Google Trends that improves the performance of Composite Leading Indicators (CLIs) to anticipate GDP trends and turning points for the Chinese economy. First, we assess the effectiveness of this new leading indicator relative to China's GDP by analyzing its statistical properties. We use fractional integration techniques to show the high degree of persistence of the new Real Time Leading Economic Indicator (RT-LEI) for China. Second, we observe the same relationship between GDP and RT-LEI in the long term using a Fractional Cointegration VAR (FCVAR) model. Third, we use a multivariate Continuous Wavelet Transform analysis to show which leading indicator best fits GDP and to identify when a structural change occurs. Finally, we forecast, using Artificial Neural Networks and a KNN model based on Machine Learning, our RT-LEI predicting the conclusion of a bearish scenario, after which the recovery begins in mid-2022.

Long time behavior of solutions for time-fractional pseudo-parabolic equations involving time-varying delays and superlinear nonlinearities

Long time behavior of solutions for time-fractional pseudo-parabolic equations involving time-varying delays and superlinear nonlinearities

Changing behaviour under unfairness: An evolutionary model of the Ultimatum Game

Experimental results on the Ultimatum Game indicate that receivers may reject non-zero offers, even though that seems irrational. The explanation is that, when players are treated unfairly, they can act against strict rationality. This paper discusses an evolutionary model of the Ultimatum Game describing how populations of players change their behaviour in time. We prove an analytical result that establishes under what conditions receivers tend to reject unfair offers. The response to unfair offers is also shown to be sensitive to different degrees of unfairness. We then introduce a Bayesian game to translate our result from populations to individual players.

Prediction of LOCA’s break size and location based on random forest and Multi Tasking Deep Neural Network

This work presents an approach for predicting break size and location in nuclear power plants (NPP) loss of coolant accidents (LOCA) with or without emergency shutdown of a nuclear reactor (SCRAM). To accomplish that, a multi-tasking deep neural network (MTDNN) model is proposed. The training and validation data sets were generated on a PWR simulator at the Human-Systems Interface Laboratory (LABIHS) at Instituto de Engenharia Nuclear (IEN), Brazil. For each simulation, the time behaviors of more than a hundred state variables were recorded and a random forest (RF) algorithm was applied to select the most relevant variables. Using the set of 15 variables selected, the MTDNN model was trained and applied to a test set, in which accuracy of 97.26 % for location and relative error of about 3.77 were obtained for break sizes between 0 and 1200 cm2.

Sticky nonlinear SDEs and convergence of McKean–Vlasov equations without confinement

We develop a new approach to study the long time behaviour of solutions to nonlinear stochastic differential equations in the sense of McKean, as well as propagation of chaos for the corresponding mean-field particle system approximations. Our approach is based on a sticky coupling between two solutions to the equation. We show that the distance process between the two copies is dominated by a solution to a one-dimensional nonlinear stochastic differential equation with a sticky boundary at zero. This new class of equations is then analyzed carefully. In particular, we show that the dominating equation has a phase transition. In the regime where the Dirac measure at zero is the only invariant probability measure, we prove exponential convergence to equilibrium both for the one-dimensional equation, and for the original nonlinear SDE. Similarly, propagation of chaos is shown by a componentwise sticky coupling and comparison with a system of one dimensional nonlinear SDEs with sticky boundaries at zero. The approach applies to equations without confinement potential and to interaction terms that are not of gradient type.

Large time behavior of signed fractional porous media equations on bounded domains

Following the methodology of Brasco (Adv Math 394:108029, 2022), we study the long-time behavior for the signed fractional porous medium equation in open bounded sets with smooth boundary. Homogeneous exterior Dirichlet boundary conditions are considered. We prove that if the initial datum has sufficiently small energy, then the solution, once suitably rescaled, converges to a nontrivial constant sign solution of a sublinear fractional Lane–Emden equation. Furthermore, we give a nonlocal sufficient energetic criterion on the initial datum, which is important to identify the exact limit profile, namely the positive solution or the negative one.

The effects of increased mental workload of air traffic controllers on time perception: Behavioral and physiological evidence

Research has shown that timing is modulated by mental workload, making duration judgments a measure of cognitive demand, alongside subjective assessments, and physiological measurements. Yet, it is unclear whether such findings can be extended in less controlled setups. By employing air traffic controllers in a real aviation environment, we tested whether tasks with different levels of cognitive load can affect their timing behavior. Participants completed temporal production, verbal estimation, and passage of time judgments, while actively engaging in real flight control sessions. Subjective assessments of task demands, as well as physiological responses (cardiac and electrodermal activity) were also measured. Accuracy of the produced intervals was measured at two distinct phases of the flight (during low-load cruising vs. high-load landing) and under two different task load manipulations (controlling one vs. two helicopters and speaking in native vs. non-native language). Analysis of interval production accuracy showed that during the high-load landing phase significant overproductions were made, compared to the low-load cruising phase, and landing two helicopters led to greater overproductions compared to landing only one. The duration of the two-helicopter sessions was significantly overestimated compared to the single-helicopter ones, and the passage of time was felt significantly faster. Subjective assessments of workload were positively correlated with the temporal estimations and passage of time judgments, and skin responses were positively correlated with the produced intervals. Overall, our results are consistent with past research, suggesting that mental workload modulates time perception in complex, real-world environments, thus making timing behavior a reliable index of the workload changes.

Numerical study of fractional Camassa–Holm equations

A numerical study of fractional Camassa–Holm equations is presented. Smooth solitary waves are constructed numerically. Their stability is studied as well as the long time behavior of solutions for general localized initial data from the Schwartz class of rapidly decreasing functions. The appearance of dispersive shock waves is explored.

Social and nonlinear dynamics unite: musical group synchrony.

Synchronization, the human tendency to align behaviors in time with others, is necessary for many survival skills. The ability to synchronize actions with rhythmic (predictable) sound patterns is especially well developed in music making. Recent models of synchrony in musical ensembles rely on pairwise comparisons between group members. This pairwise approach to synchrony has hampered theory development, given current findings from social dynamics indicating shifts in members' influence within larger groups. We draw on social theory and nonlinear dynamics to argue that emergent properties and novel roles arise in musical group synchrony that differ from individual or pairwise behaviors. This transformational shift in defining synchrony sheds light on successful outcomes as well as on disruptions that cause negative behavioral outcomes.

Analysis of a two-layer energy balance model: Long time behavior and greenhouse effect.

We study a two-layer energy balance model that allows for vertical exchanges between a surface layer and the atmosphere. The evolution equations of the surface temperature and the atmospheric temperature are coupled by the emission of infrared radiation by one level, that emission being partly captured by the other layer, and the effect of all non-radiative vertical exchanges of energy. Therefore, an essential parameter is the absorptivity of the atmosphere, denoted εa. The value of εa depends critically on greenhouse gases: increasing concentrations of CO2 and CH4 lead to a more opaque atmosphere with higher values of ϵa. First, we prove that global existence of solutions of the system holds if and only if εa∈(0,2) and blow up in finite time occurs if εa>2. (Note that the physical range of values for εa is (0,1].) Next, we explain the long time dynamics for εa∈(0,2), and we prove that all solutions converge to some equilibrium point. Finally, motivated by the physical context, we study the dependence of the equilibrium points with respect to the involved parameters, and we prove, in particular, that the surface temperature increases monotonically with respect to εa. This is the key mathematical manifestation of the greenhouse effect.

VOCALIZATION AND BEHAVIOR OF THE SOOTY-HEADED BULBUL (<i>PYCNONOTUS AURIGASTER</i>), THE STREAK-EARED BULBUL (<i>PYCNONOTUS CONRADI</i>) AND THE STRIPE-THROATED BULBUL (<i>PYCNONOTUS FINLAYSONI</i>) (PYCNONOTIDAE, AVES) IN SOUTHERN VIETNAM

The bulbul family Pycnonotidae is an Old-World group of tropical birds that plays important roles in tree seed dispersal. The behavior and vocalization of bulbuls have been studied only in a few species. The present study’s objective is to describe, for the first time, the acoustic and social behavior of three species of bulbuls of the genus Pycnonotus: the Sooty-headed bulbul (P. aurigaster), the Streak-eared bulbul (P. conradi), and the Stripe-throated bulbul (P. finlaysoni). Field studies were conducted from November 2021 to May 2022 in the Cattien National Park, Dong Nai Province, Vietnam, where all three species are sympatric and tend to inhabit disturbed biotopes. We analyzed “observations”, that is, a single record of a bird or a group of birds of a given species. During each observation (about 800 in total), the behavior of the birds was described and, when possible, vocalizations were recorded. The total duration of phonograms of all three species amounted to ca 227 min. The sooty-headed and streak-eared bulbuls are social birds that kept pairs throughout the year, but often, especially during the non-breeding season, gathered in larger groups. Pair members and individuals from neighboring pairs maintained acoustic contact with each other all the time. To do so, they used calls: broadband calls (noise sounds without clear structure, but with a wide continuous frequency spectrum) emitted by streak-eared bulbuls, vs tonal calls (musical sounds showing one clearly defined frequency) by sooty-headed bulbuls. Both these species singing were only rarely observed, this possibly being due to reduced territorial behavior in these birds. The Stripe-throated bulbul differs from the other two in singing more frequently, along with producing calls, and the song could be used for territorial purposes. We assume that territorial behavior is better expressed in stripe-headed bulbuls than in the other two species. However, even stripe-throated bulbuls did not react to playback simulated territorial intrusion in our experiments. We assume that vocalizations play important roles in the communication of the three species because we noted these or those sounds in almost all observations. Moreover, we observed a general increase in vocal activity at the beginning of the breeding season (February–March). In addition, during this time, bulbuls were most often to sing.

Non–uniform decay of solutions to the incompressible magneto–micropolar fluids with/without magnetic diffusion and spin viscosity

We are concerned with the long time behavior of solutions to the incompressible magneto–micropolar fluids with/without magnetic diffusion and spin viscosity in two and three dimensions. When the magnetic diffusion is absent, we show that L2–norm of fluid velocity and micro–rotational velocity vanishes and L2–norm of the magnetic field converges to a non–negative constant as time tends to infinity. Moreover, when both magnetic diffusion and spin viscosity are present and the initial data belongs to L2, we prove that the solutions decay to zero without a rate, and this non–uniform decay is optimal. The proofs are based on Fourier splitting method, low–frequency and high–frequency decomposition techniques and delicate energy estimates.

Energy efficiency of N2 vibrational excitation in the spark-and-glow phases of a long-pulse air discharge at atmospheric pressure

The vibrational excitation of N2 molecules has a significant impact on plasma chemical synthesis, including nitrogen fixation and ammonia formation, by reducing the energy barrier of chemical reactions. However, experimental data for energy efficiency of N2 vibrational excitation is very rare. In this work, vibrational coherent anti-Stokes Raman scattering was applied to a 200 μs long-pulse air plasma, and the time behaviours of rotational and vibrational temperatures of N2 in two different discharge modes, namely the spark and glow modes in the long discharge pulse, were quantified. It reveals that the spark discharge produced a vibrational temperature exceeding 5000 K but with a gas temperature as low as 400 K, while the glow discharge resulted in efficient gas heating with a gas temperature as high as 3500 K and a vibrational temperature higher than 5000 K. Combined with the 0D simulation of the air plasma, it demonstrates that the energy efficiency of N2 vibrational excitation in the glow phase is about three times higher than that of the spark phase. These results provide essential inspiration for further studies of plasma chemical synthesis dominated by N2 vibrational excitation.

62 Neural Correlates of Cognitive Function in the Basal Ganglia

Objective:Timing, or the decision of when to act, is essential to mammalian behaviors from escaping predators to driving a car. It requires cognitive functions such as working memory for time-based rules and attention to the passing of time. Thus, it can be used as a proxy for higher order executive functions that are difficult to measure but are impaired in many neurological disorders. Therefore, insights from studies of interval timing, tasks which require estimating time intervals of several seconds, have great value for our understanding of human disease. Crucial to timing is the basal ganglia, which integrates cortical activity with midbrain dopamine signals and sends out signals to the spinal cord that regulate movement, motivation, and other behaviors. We have previously found that within the basal ganglia, medium spiny neurons of the striatum exhibit ramping activity in time-related tasks. In other words, they gradually increase or decrease firing frequency across a timed interval, and this is thought to encode time. Yet it is still unknown how the encoding of time is translated into time-based motor responses. To answer this question, we turned to the external globus pallidus (GPe) because it is a regulatory hub within the basal ganglia and is thus well positioned to regulate timing behavior. We sought to examine how the GPe functions in response to time-based demands.Participants and Methods:We recorded from neuronal ensembles using 16 channel electrode arrays implanted in the GPe of five mice while they performed an interval timing task called the switch interval timing task. Spike sorting was then used to identify signal from individual neurons.Results:Data were compiled from 43 neurons over several trials. Principal component analysis of neural firing activity was then conducted and revealed a downward ramping pattern in GPe neurons during interval timing trials. Data were then separated based on trials in which mice made correct decisions and those in which mice made a mistake. We found that when mice make correct timing decisions, there is downward ramping activity in the GPe, yet when mice make timing mistakes, this ramping pattern is lost.Conclusions:Our findings suggest that the GPe processes timing signals through ramping activity, before projecting to the output nuclei of the basal ganglia. This is a novel finding and contributes to a growing understanding of the temporal code of the basal ganglia. The full extent of this code is still unknown, but this insight contributes to a better understanding of how the globus pallidus represents cognition. If we can better explain the neural correlates of timing, we can use this knowledge to inform therapeutic interventions for basal ganglia dysfunction, which could have profound implications for diseases like Parkinson’s disease, which affects millions around the world.

Comparison study of supercritical water gasification for hydrogen production on a continuous flow versus a batch reactor

This study compares batch and continuous supercritical water gasification (SCWG) processes for green hydrogen production from biomass. It offers insights for optimizing processes, enhancing yields, quality, and energy efficiency, assessing scale-up feasibility, and supporting techno-economic analyses. Glucose, glycerol, and black liquor were SCWG-treated at 500 °C with K2CO3 catalyst in a self-built continuous-flow reactor (150 g/h) and a batch reactor (75 mL). Comparisons primarily focused on gas product yields. Batch reactors outperformed continuous-flow reactors in hydrogen (glucose: 1.53 to 0.9 mmol/g, glycerol: 7.22 to 1.14 mmol/g, black liquor: 2.88 to 1.74 mmol/g) and total gas yields due to differences in reaction time and heating behavior. Temperature effects on continuous operation (450–600 °C) were studied, with glycerol showing the highest hydrogen yield increase (from 1.21 to 4.30 mmol/g). The study discusses the applicability of both reactors for biomass SCWG processes and their implications for sustainable green hydrogen production from renewable feedstocks.

Intelligent Personalized Lighting Control System for Residents

The demand for personalized lighting environments based on households is steadily increasing among users. This article proposes a novel intelligent control system for personalized lighting in home environments, aiming to automatically capture user information, such as homecoming time and light switching behavior, in order to train a model that intelligently regulates the lights for users. Facial recognition technology is employed by this system to identify users and record their lighting data. Subsequently, nine commonly used machine learning models were evaluated, revealing that the error back-propagation neural network algorithm exhibits excellent performance in time-series analysis. The BPNN weights were optimized using genetic algorithms, resulting in an improved coefficient of determination (R2) of 0.99 for turn-on time and 0.82 for turn-off time test sets. Furthermore, testing was conducted on data collection duration which demonstrated that even with only 20 time-series data collected from new users, the model still displayed exceptional performance in training prediction tasks. Overall, this system effectively identifies users and automatically adjusts the lighting environment according to their preferences, providing comfortable and convenient lighting conditions tailored to individual needs. Consequently, a broader goal of energy conservation and environmental sustainability can be achieved.