Dynamics Of Components Research Articles

Contrasting Norway spruce disturbance dynamics in managed forests and strict forest reserves in Slovakia

AbstractForest disturbances are intensifying globally, yet regional drivers of these dynamics remain poorly understood. We investigated recent disturbance intensities in Norway spruce (Picea abies L.) forests in Slovakia (Central Europe) with different management objectives in 2000–2017 based on Landsat imagery. We focused on 122 strict reserves without any management, their actively managed surroundings (500 m and 2000 m buffers), and managed production forests beyond the buffer areas. We used generalized additive mixed models to test for differences in temporal trends of disturbance intensity among these management categories. We found that disturbance intensity was increasing in all management categories during the studied period. The increase was more pronounced in the managed forests (compound annual disturbance rate 1.76% year−1) and the 2000 m buffer (2.21% year−1) than in the strict reserves (0.58% year−1). The predicted cumulative disturbance during the 18-year period was 9.9% in the reserves and 30.5% in the 2000 m buffer. We found that forests in nature reserves can be more resistant to disturbances than forests managed for timber production, despite management efforts to control disturbances in managed forests. Our findings can help reconcile the different perceptions of natural disturbances and their management in Central Europe and support climate-adapted management strategies that consider natural disturbances as an indispensable component of ecosystem dynamics.

Spatial and cross-sectoral relationships in business entry dynamics around a highway corridor

Inter-business networks are important components of business dynamics and spatial clusters. Extensive literature proclaims the existence of a variety of networks and benefits of diversity within. However, the literature falls short to exhibit the subsistence of connections between economic activities which invariably contribute towards entry decisions of business establishments. In this paper, using National Establishment Time Series (NETS) database, we analyse establishments entering the region around U.S.-400, largely in Kansas, across a period of 20 years (1992–2011). The establishments are categorised into 20 industrial sectors based on their economic activities. Using spatial econometric models and partial least squares regression, yearly relationships (attraction/impedance) among these categories are estimated. The results provide evidence that relationships amidst pre-existing and new-entrants are indeed significant in business entry. This can be critical in understanding and rationale of freight vehicle flows and guide towards corridor utilisation aspects. The inferred relationships could be used to understand how alterations in one sector may perturb other sectors and to inform about upgrading regional attraction, retention and growth-related policies.

Egestion rates of microplastic fibres in fish scaled to in situ concentration and fish density

AbstractMicroplastics (particles <5 mm) are commonly found in aquatic organisms across taxonomic groups and ecosystems. However, the egestion rate of microplastics from aquatic organisms and how egestion rates compare to other rates of microplastic movement in the environment are sparsely documented.We fed microplastic fibres to round gobies (Neogobius melanostomus), an abundant, invasive species in the Laurentian Great Lakes. We conducted two trials where round gobies were fed microplastic‐containing food either a single time (1 day) or every day over 7 days.There was no difference in microplastic egestion rates from the 1 day or 7 day feeding trials, suggesting no impact of duration of exposure on egestion (exponential decay rate = −0.055 [±0.016SE] and −0.040 [±0.007SE], respectively). Turnover time of microplastics (i.e., average time from ingestion to egestion) in the gut ranged from 18.2 to 25.0 hr, similar to published values for other freshwater taxa.We also measured microplastics in the digestive tracts of round gobies collected directly from Lake Michigan, U.S.A. Using published values for round goby density and microplastic concentration at the study sites, we calculated areal egestion rate by round gobies (no. particles m–2 day–1), and compared it to riverine microplastic export (no. particles m–2 day–1). Both area‐based rates were of the same order of magnitude, suggesting that round goby egestion could be an important, and potentially overlooked component of microplastic dynamics at the ecosystem scale.Animal egestion is well‐known as a major component of nutrient and carbon cycling. However, direct measurements of microplastic fluxes in the environment that include animal egestion rates are uncommon. An ecosystem ecology approach is needed to meet the emerging challenge of generating microplastic budgets for freshwater environments and elsewhere, thereby informing management and mitigation of plastic pollution at a global scale.

Forecasting the daily variability discharge in the fluvial system of the Paraná River: an ODPC hydrology application

ABSTRACT The relation between discharge and matters of social economy is of constant interest for decision makers. Unexpected daily discharge fluctuations could easily affect agriculture and tourism, among other things. Moreover, because discharge is considered a stochastic variable, studies of new resources to prevent and reduce their negative impacts are needed. We propose the novel application of a technique known as one-sided dynamical principal components (ODPC) to the field of hydrology. This technique allowed us to model and predict the daily variability of the streamflow of three gauge stations of the La Plata Basin. We did a comparison between ODPC and the traditional models used in the field for time series forecasts. This comparison demonstrated that the ODPC method provides some improvement for treatment and forecasting of the daily variability in discharge.

Intersegmental coordination of the central pattern generator via interleaved electrical and chemical synapses in zebrafish spinal cord.

A significant component of the repetitive dynamics during locomotion in vertebrates is generated within the spinal cord. The legged locomotion of mammals is most likely controled by a hierarchical, multi-layer spinal network structure, while the axial circuitry generating the undulatory swimming motion of animals like lamprey is thought to have only a single layer in each segment. Recent experiments have suggested a hybrid network structure in zebrafish larvae in which two types of excitatory interneurons (V2a-I and V2a-II) both make first-order connections to the brain and last-order connections to the motor pool. These neurons are connected by electrical and chemical synapses across segments. Through computational modeling and an asymptotic perturbation approach we show that this interleaved interaction between the two neuron populations allows the spinal network to quickly establish the correct activation sequence of the segments when starting from random initial conditions, as needed for a swimming spurt, and to reduce the dependence of the intersegmental phase difference (ISPD) of the oscillations on the swimming frequency. The latter reduces the frequency dependence of the waveform of the swimming motion. In the model the reduced frequency dependence is largely due to the different impact of chemical and electrical synapses on the ISPD and to the significant spike-frequency adaptation that has been observed experimentally in V2a-II neurons, but not in V2a-I neurons. Our model makes experimentally testable predictions and points to a benefit of the hybrid structure for undulatory locomotion that may not be relevant for legged locomotion.

Conformal metric-affine gravities

We revisit the gauge symmetry related to integrable projective transformations in metric-affine formalism, identifying the gauge field of the Weyl (conformal) symmetry as a dynamical component of the affine connection. In particular, we show how to include the local scaling symmetry as a gauge symmetry of a large class of geometric gravity theories, introducing a compensator dilaton field that naturally gives rise to a Stückelberg sector where a spontaneous breaking mechanism of the conformal symmetry is at work to generate a mass scale for the gauge field. For Ricci-based gravities that include, among others, General Relativity, f(R) and f(R, R μν R μν) theories and the EiBI model, we prove that the on-shell gauge vector associated to the scaling symmetry can be identified with the torsion vector, thus recovering and generalizing conformal invariant theories in the Riemann-Cartan formalism, already present in the literature.

PROPOSAL AND VALIDITY OF A SCALE OF TEAMWORK’S INTERNAL DYNAMICS IN INDIGENOUS WOMEN

Teamwork can be understood a process where the members are recognised as a unit, that shows interdependence but works together for a common objective; this practice is relevant to achieve the progress and develop, especially in vulnerable groups. The aim of the study was to evaluate the validity and reliability from the scores obtained of an instrument with three components of internal dynamics in Teamwork (Task Interdependence, Group Potency and Psychological Safety) in indigenous women of Mexico. The sample consisted of 96 participants. Internal consistency was evaluated by using the Cronbach alpha coefficient, the internal structure was determined by using the principal component factorial analysis with Varimax rotation. The scores on each of the subscales showed an acceptable degree of internal consistency (αinter=.712, αgroup=.701, αacceptance=.716 y αsupport=.682). The factor analysis showed that in two of the three sections (Task Interdependence and Group Potency) the items loaded to a component that explained 47.12% and 44.99% of the variance, respectively. In psychological safety, the items were grouped into two components, explaining 60.54 % of the total variance. The version of a scale of Teamwork proposed in this work is a valid and reliable version that could be useful for the evaluation of teamwork in indigenous women.

Many-Body Molecular Interactions in a Memristor.

Electronic transitions in molecular-circuit elements hinge on complex interactions between molecules and ions, offering a multidimensional parameter space to embed, access, and optimize material functionalities for target-specific applications. This opportunity is not cultivated in molecular memristors because their low-temperature charge transport, which is a route to decipher molecular many-body interactions, is unexplored. To address this, robust, temperature-resilient molecular memristors based on a Ru complex of an azo aromatic ligand are designed, and current-voltage sweep measurements from room temperature down to 2 K with different cooling protocols are performed. By freezing out or activating different components of supramolecular dynamics, the local Coulombic interactions between the molecules and counterions that affect the electronic transport can be controlled. Operating conditions are designed where functionalities spanning bipolar, unipolar, nonvolatile, and volatile memristors with sharp as well as gradual analog transitions are captured within a single device. A mathematical design space evolves, thereof comprising 36 tuneable parameters in which all possible steady-state functional variations in a memristor characteristic can be attainable. This enables a deterministic design route to engineer neuromorphic devices with unprecedented control over the transformation characteristics governing their functional flexibility and tunability.

Slow protein dynamics probed by time-resolved oscillation crystallography at room temperature.

The development of serial crystallography over the last decade at XFELs and synchrotrons has produced a renaissance in room-temperature macromolecular crystallography (RT-MX), and fostered many technical and methodological breakthroughs designed to study phenomena occurring in proteins on the picosecond-to-second timescale. However, there are components of protein dynamics that occur in much slower regimes, of which the study could readily benefit from state-of-the-art RT-MX. Here, the room-temperature structural study of the relaxation of a reaction intermediate at a synchrotron, exploiting a handful of single crystals, is described. The intermediate in question is formed in microseconds during the photoreaction of the LOV2 domain of phototropin 2 from Arabidopsis thaliana, which then decays in minutes. This work monitored its relaxation in the dark using a fast-readout EIGER X 4M detector to record several complete oscillation X-ray diffraction datasets, each of 1.2 s total exposure time, at different time points in the relaxation process. Coupled with in crystallo UV-Vis absorption spectroscopy, this RT-MX approach allowed the authors to follow the relaxation of the photoadduct, a thio-ether covalent bond between the chromophore and a cysteine residue. Unexpectedly, the return of the chromophore to its spectroscopic ground state is followed by medium-scale protein rearrangements that trigger a crystal phase transition and hinder the full recovery of the structural ground state of the protein. In addition to suggesting a hitherto unexpected role of a conserved tryptophan residue in the regulation of the photocycle of LOV2, this work provides a basis for performing routine time-resolved protein crystallography experiments at synchrotrons for phenomena occurring on the second-to-hour timescale.

Non-conventional mitochondrial permeability transition: Its regulation by mitochondrial dynamics

Mitochondrial permeability transition (MPT) is a phenomenon that the inner mitochondrial membrane (IMM) loses its selective permeability, leading to mitochondrial dysfunction and cell injury. Electrophysiological evidence indicates the presence of a mega-channel commonly called permeability transition pore (PTP) whose opening is responsible for MPT. However, the molecular identity of the PTP is still under intensive investigations and debates, although cyclophilin D that is inhibited by cyclosporine A (CsA) is the established regulatory component of the PTP. PTP can also open transiently and functions as a rapid mitochondrial Ca2+ releasing mechanism. Mitochondrial fission and fusion, the main components of mitochondrial dynamics, control the number and size of mitochondria, and have been shown to play a role in regulating MPT directly or indirectly. Studies by us and others have indicated the potential existence of a form of transient MPT that is insensitive to CsA. This “non-conventional” MPT is regulated by mitochondrial dynamics and may serve a protective role possibly by decreasing the susceptibility for a frequent or sustained PTP opening; hence, it may have a therapeutic value in many disease conditions involving MPT.

The East Asian Summer Monsoon Response to Global Warming in a High Resolution Coupled Model: Mean and Extremes

Current climate models still have considerable biases in the simulation of the East Asian summer monsoon (EASM), which in turn reduces their reliability of monsoon projections under global warming. We hypothesize that a higher-resolution coupled climate model with atmospheric and oceanic components at horizontal resolutions of 0.25° and 0.1°, respectively, will better capture regional details and extremes of the EASM. Present-day (PD), 2 × CO2 and 4 × CO2 simulations are conducted with the Community Earth System Model (CESM1.2.2) to evaluate PD simulation performance and quantify future changes. Indeed, our PD simulation well reproduces the climatological seasonal mean and intra-seasonal northward advancement of the monsoon rainband, as well as climate extremes. Compared with the PD simulation, the perturbed CO2 experiments show an intensified EASM response to CO2-induced warming. We find that the precipitation increases of the Meiyu-Baiu-Changma band are caused by comparable contributions from the dynamical and thermodynamical components in 2 × CO2, while they are more driven by the thermodynamical component in 4 × CO2 due to stronger upper atmospheric stability. The regional changes in the probability distribution of the temperature show that extreme temperatures warm faster than the most often temperatures, increasing the skewness. Fitting extreme precipitation values with a generalized Pareto distribution model reveals that they increase significantly in 4 × CO2. Changes of temperature extremes scale with the CO2 concentrations over the monsoon domain but not for precipitation extreme changes. The 99th percentile of precipitation over the monsoon region increases at a super Clausius-Clapeyron rate, ~ 8% K–1, which is mainly caused by increased moisture transport through anomalous southerly winds.

Molecular dynamics simulation on the Thermosinus carboxydivorans pfl ZTP riboswitch by ligand binding

Riboswitches are RNA molecules that can regulate gene expression which is affected by ligand-binding during cotranscriptional folding process. However, the role of ligand during the folding is still unclear. In this study, the pfl domain of Thermosinus carboxydivorans ZTP riboswitch was discussed. The ligand is molecule ZMP. We mainly analyzed the change of ZMP-free and ZMP-bound aptamer domain by the dynamics simulation method. Structural features by calculating their RMSD, RMSF, etc. are analyzed. The results demonstrate that the binding domain require the presence of ZMP to maintain a stable fold. It also suggested that ZMP specificly binding to ZTP can generate more hydrogen bonds in the binding domain. Through the calculation of binding free energy decomposition of each nucleotide, molecule ZMP was found to promote the recognition and binding process of ligands by controlling some special nucleotides in the process of ligand binding. At last, the dynamical correlation and components of conformational motions were both applied to explore the effect of molecule ZMP to ZTP riboswitch. In general, ZMP can effectively affect the motions of the pfl riboswitch and facilitate the folding process of the ZTP riboswitch.These results may provide some new ideas for structural changes in riboswitches and their cotranscriptional folding process.

Toward a decade of ocean science for sustainable development through acoustic animal tracking.

The ocean is a key component of the Earth's dynamics, providing a great variety of ecosystem services to humans. Yet, human activities are globally changing its structure and major components, including marine biodiversity. In this context, the United Nations has proclaimed a Decade of Ocean Science for Sustainable Development to tackle the scientific challenges necessary for a sustainable use of the ocean by means of the Sustainable Development Goal 14 (SDG14). Here, we review how Acoustic animal Tracking, a widely distributed methodology of tracking marine biodiversity with electronic devices, can provide a roadmap for implementing the major Actions to achieve the SDG14. We show that acoustic tracking can be used to reduce and monitor the effects of marine pollution including noise, light, and plastic pollution. Acoustic tracking can be effectively used to monitor the responses of marine biodiversity to human‐made infrastructures and habitat restoration, as well as to determine the effects of hypoxia, ocean warming, and acidification. Acoustic tracking has been historically used to inform fisheries management, the design of marine protected areas, and the detection of essential habitats, rendering this technique particularly attractive to achieve the sustainable fishing and spatial protection target goals of the SDG14. Finally, acoustic tracking can contribute to end illegal, unreported, and unregulated fishing by providing tools to monitor marine biodiversity against poachers and promote the development of Small Islands Developing States and developing countries. To fully benefit from acoustic tracking supporting the SDG14 Targets, trans‐boundary collaborative efforts through tracking networks are required to promote ocean information sharing and ocean literacy. We therefore propose acoustic tracking and tracking networks as relevant contributors to tackle the scientific challenges that are necessary for a sustainable use of the ocean promoted by the United Nations.

Quantum radiation and dissipation in relation to classical radiation and radiation reaction

This work continues the investigation of radiation phenomena from atom-field interactions, extending our earlier study of quantum radiation from a stationary atom's internal degree of freedom, modeled by a harmonic oscillator, to the emittance of classical radiation. By assuming that the atom interacts with a quantum scalar field initially in a coherent state, we show how a stochastic component of the internal dynamics of the atom arises from the vacuum fluctuations of the field, resulting in the emittance of quantum radiation, whose reaction induces quantum dissipation in the internal dynamics. We also show how the deterministic mean field drives the internal classical mean component to emit classical radiation and receive classical radiation reaction. Both components are statistically distinct and fully decoupled. It is clearly seen that the effects of the vacuum fluctuations of the field are matched with those of quantum radiation reaction, not with classical radiation reaction, as the folklore goes. In contrast to the quantum component of the atom's internal dynamics, which always equilibrates, the relaxation dynamics of the classical component largely depends on the late-time behavior of the mean field. For the values of the parameters defining the coherent state of the field much greater than unity, if the mean field remains periodic, then the internal dynamics of the atom will appear classical and periodic. If the mean field diminishes with time, then the classical component of the atom's internal dynamics subsides but the quantum component will abide and dynamically equilibrate. This also explains why quantum radiation from a stationary atom is not observed, and a probe located far away only sees classical radiation. Our analysis therefore paints a continuum landscape starting from vacuum fluctuations in the quantum field to classical radiation and radiation reaction.

Reservoir computing with diverse timescales for prediction of multiscale dynamics

Machine learning approaches have recently been leveraged as a substitute or an aid for physical/mathematical modeling approaches to dynamical systems. To develop an efficient machine learning method dedicated to modeling and prediction of multiscale dynamics, we propose a reservoir computing (RC) model with diverse timescales by using a recurrent network of heterogeneous leaky integrator (LI) neurons. We evaluate computational performance of the proposed model in two time series prediction tasks related to four chaotic fast-slow dynamical systems. In a one-step-ahead prediction task where input data are provided only from the fast subsystem, we show that the proposed model yields better performance than the standard RC model with identical LI neurons. Our analysis reveals that the timescale required for producing each component of target multiscale dynamics is appropriately and flexibly selected from the reservoir dynamics by model training. In a long-term prediction task, we demonstrate that a closed-loop version of the proposed model can achieve longer-term predictions compared to the counterpart with identical LI neurons depending on the hyperparameter setting.Received 23 August 2021Accepted 28 June 2022DOI:https://doi.org/10.1103/PhysRevResearch.4.L032014Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasNeuronal dynamicsPhysical SystemsDynamical systemsMultiple time scale dynamicsNonlinear Dynamics

The cosmological constant problem and running vacuum in the expanding universe.

It is well known that quantum field theory (QFT) induces a huge value of the cosmological constant (CC), [Formula: see text], which is outrageously inconsistent with cosmological observations. We review here some aspects of this fundamental theoretical conundrum (the cosmological constant problem, CCP) and strongly argue in favour of the possibility that the cosmic vacuum density [Formula: see text] may be mildly evolving with the expansion rate [Formula: see text]. Such a 'running vacuum model' (RVM) proposal predicts an effective dynamical dark energy without postulating new ad hoc fields (quintessence and the like). Using the method of adiabatic renormalization within QFT in curved space-time, we find that [Formula: see text] acquires a dynamical component [Formula: see text] caused by the quantum matter effects. There are also [Formula: see text] ([Formula: see text]) contributions, some of which may trigger inflation in the early universe. Remarkably, the evolution of the adiabatically renormalized [Formula: see text] is not affected by dangerous terms proportional to the quartic power of the masses ([Formula: see text]) of the quantized matter fields. Traditionally, these terms have been the main source of trouble as they are responsible for the extreme fine-tuning feature of the CCP. In the context under study, however, the late time [Formula: see text] around [Formula: see text] is given by a dominant term ([Formula: see text]) plus the aforementioned mild dynamical component [Formula: see text] (with [Formula: see text]), which makes the RVM to mimic quintessence. Finally, on the phenomenological side, we show that the RVM may be instrumental in alleviating some of the most challenging problems (so-called 'tensions') afflicting nowadays the observational consistency of the 'concordance' [Formula: see text]CDM model, such as the [Formula: see text] and [Formula: see text] tensions. This article is part of the theme issue 'The future of mathematical cosmology, Volume 2'.

터빈 블레이드 주위 유동 해석을 위한 자동 정렬 격자 생성

A computational grid is a crucial component in computational fluid dynamics, that greatly affects the accuracy and the cost of a numerical analysis. However, generating a grid with high quality is challenging and time-consuming, for turbomachinery blades with various shapes and configurations. In addition, the user-dependency in grid generation deteriorates the reliability of the analysis. We develop an algorithm that can automatically generate a structured grid for simulations of flow over a turbomachinery blade. Using an elliptic grid generation method, a high-quality O-type grid with high grid orthogonality on the wall is generated. Users only need to specify basic grid specifications such as grid number and resolution. The efficacy of the developed algorithm is evaluated for various two-dimensional and three-dimensional blades.

Laser-Dressed Molecular Point Groups in the Kramers-Henneberger Oscillating Frame-of-Reference: Selection Rules for Higher Harmonic Generation.

Point groups of molecules in a laser, within the Kramers-Henneberger (KH) oscillating frame for laser-dressed states, is given in this work. In a Fourier series of the time-dependent potential, the zeroth-order time-average yields the point group of the laser-dressed molecule. Various laser polarizations and relative molecular orientation induce a new point group or retain the original point group. The dynamical Fourier components (KH potentials) classify as irreducibles of this new laser-dressed point group. Recurrence of unique irreducibles in the Fourier expansion dictates the dynamical symmetry of the Floquet Hamiltonian. Hence, selection rules for harmonic generation spectra are Nk ± 1 in harmonic order, where N is the number of unique irreducibles and .

Commensuration effects on skyrmion Hall angle and drag for manipulation of skyrmions on two-dimensional periodic substrates

We examine the dynamics of an individually driven skyrmion moving through a background lattice of skyrmions coupled to a 2D periodic substrate as we vary the ratio of the number of skyrmions to the number of pinning sites across commensurate and incommensurate conditions. As the skyrmion density increases, the skyrmion Hall angle is nonmonotonic, dropping to low or zero values in commensurate states and rising to an enhanced value in incommensurate states. Under commensuration, the driven skyrmion is channeled by a symmetry direction of the pinning array and exhibits an increased velocity. At fillings for which the skyrmion Hall angle is zero, the velocity has a narrow band noise signature, while for incommensurate fillings, the skyrmion motion is disordered and the velocity noise is broad band. Under commensurate conditions, multi-step depinning transitions appear and the skyrmion Hall angle is zero at low drives but becomes finite at higher drives, while at incommensurate fillings there is only a single depinning transition. As the gyrotropic component of the skyrmion dynamics, called the Magnus force, increases, peaks in the velocity that appear in commensurate regimes cross over to dips, and new types of directional locking effects can arise in which the skyrmion travels along other symmetry directions of the background lattice. At large Magnus forces, and particularly at commensurate fillings, the driven skyrmion can experience a velocity boost in which the skyrmion moves faster than the applied drive due to the alignment of the Magnus-induced velocity with the driving direction. In some cases, an increase of the Magnus force can produce regimes of enhanced pinning when the skyrmion is forced to move along a nonsymmetry direction of the periodic pinning array. This is in contrast to systems with random pinning, where increasing the Magnus force generally reduces the pinning effect. We demonstrate these dynamics for both square and triangular substrates and map out the different regimes as a function of filling fraction, pinning force, and the strength of the Magnus force in a series of dynamic phase diagrams.

Drifted escape from the finite interval.

Properties of the noise-driven escape kinetics are mainly determined by the stochastic component of the system dynamics. Nevertheless, the escape dynamics is also sensitive to deterministic forces. Here, we are exploring properties of the overdamped drifted escape from finite intervals under the action of symmetric α-stable noises. We show that the properly rescaled mean first passage time follows the universal pattern as a function of the generalized Pécklet number, which can be used to efficiently discriminate between domains where drift or random force dominate. Stochastic driving of the α-stable type is capable of diminishing the significance of the drift in the regime when the drift prevails.