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1.
Assessment ; : 10731911241266286, 2024 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-39138593

RESUMO

We examined continuous affect drawings as innovative measure of affective experiences over time. Intensive longitudinal data often rely on discrete assessments, containing "blind spots" between measurements. With continuous affect drawings participants visually depict their affect fluctuations between assessments. In an experience sampling study, participants (N = 115) rated their momentary positive and negative affect 6 times daily. From the second daily rating on, they additionally drew their positive and negative affect changes and reported affective events between assessments. They received one measurement burst between assessments daily. The strength of the approach is a substantial amount of informational gain (average 7%) over linearly interpolated points between assessments. The additional information was subsequently categorized into positive and negative affect peaks and valleys, each occurring once a day per person on average. The probability of detecting peaks and valleys increased with reported events. The drawings correlated positively with momentary affect scores from the burst. Yet, the drawing predicted the bursts less well suggesting that the momentary ratings may yield different information than the drawings. Although the timing of retrospective drawings is less precise than individual momentary assessments, this method provides a comprehensive understanding of affective experiences between assessments, offering a unique perspective on affect dynamics.

2.
Soc Networks ; 76: 174-190, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-39006096

RESUMO

Social relations are embedded in material, cultural, and institutional settings that affect network dynamics and the resulting topologies. For example, romantic entanglements are subject to social and cultural norms, interfirm alliances are constrained by country-specific legislation, and adolescent friendships are conditioned by classroom settings and neighborhood effects. In short, social contexts shape social relations and the networks they give rise to. However, how and when they do so remain to be established. This paper presents network ecology as a general framework for identifying how the proximal environment shapes social networks by focusing interactions and social relations, and how these interactions and relations in turn shape the environment in which social networks form. Tie fitness is introduced as a metric that quantifies how well particular dyadic social relations would align with the setting. Using longitudinal networks collected on two cohorts each in 18 North American schools, i.e., 36 settings, we develop five generalizable observations about the time-varying fitness of adolescent friendship. Across all 252 analyzed networks, tie fitness predicted new tie formation, tie longevity, and tie survival. Dormant fit ties cluster in relational niches, thereby establishing a resource base for social identities competing for increased representation in the relational system.

3.
Front Netw Physiol ; 4: 1399352, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38962160

RESUMO

Physiological networks are usually made of a large number of biological oscillators evolving on a multitude of different timescales. Phase oscillators are particularly useful in the modelling of the synchronization dynamics of such systems. If the coupling is strong enough compared to the heterogeneity of the internal parameters, synchronized states might emerge where phase oscillators start to behave coherently. Here, we focus on the case where synchronized oscillators are divided into a fast and a slow component so that the two subsets evolve on separated timescales. We assess the resilience of the slow component by, first, reducing the dynamics of the fast one using Mori-Zwanzig formalism. Second, we evaluate the variance of the phase deviations when the oscillators in the two components are subject to noise with possibly distinct correlation times. From the general expression for the variance, we consider specific network structures and show how the noise transmission between the fast and slow components is affected. Interestingly, we find that oscillators that are among the most robust when there is only a single timescale, might become the most vulnerable when the system undergoes a timescale separation. We also find that layered networks seem to be insensitive to such timescale separations.

4.
MethodsX ; 12: 102783, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38966713

RESUMO

In recent years, frequent and substantial area-wide power outages have underscored the critical need for cities to possess robust backup power sources capable of swift response to prevent prolonged power system disruptions. Electric vehicles can contribute electricity to the power grid using vehicle-to-grid technology. The power delivered by electric vehicles in this context is termed as response capability. However, existing studies have overlooked response capability dynamics during transitions between electric vehicle states-such as the shift from charging or discharging to an idle state, thereby hindering a comprehensive understanding of this aspect. Hence, this paper introduces a multi-timescale response capability prediction model that evaluates the electric vehicle's state of charge to ensure users' requirements are met for upcoming trips. To better assess users' travel demand, the gravity model is employed as a precursor to response capability prediction to further enhance the validity of the prediction outcomes. Three neighborhoods in Los Angeles have been chosen for analysis: Downtown, Lincoln Heights, and Silver Lake. Predictions indicate that neglecting the response capability when electric vehicles undergo state transformation can lead to a differential response capability ranging from 2000 kWh to 4000 kWh, resulting in a loss of prediction accuracy by 20 % to 25 %.•The response capability of EV is non-zero during state transformations•Users' travel demand assessment•Seamless integration of vehicle-to-grid technology into the power grid.

5.
J Colloid Interface Sci ; 674: 951-958, 2024 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-38959740

RESUMO

HYPOTHESIS: Our hypothesis is that dynamic interfacial tension values as measured by the partitioned-Edge-based Droplet GEneration (EDGE) tensiometry can be connected to those obtained with classical techniques, such as the automated drop tensiometer (ADT), expanding the range of timescales towards very short ones. EXPERIMENTS: Oil-water and air-water interfaces are studied, with whey protein isolate solutions (WPI, 2.5 - 10 wt%) as the continuous phase. The dispersed phase consists of pure hexadecane or air. The EDGE tensiometer and ADT are used to measure the interfacial (surface) tension at various timescales. A comparative assessment is carried out to identify differences between protein concentrations as well as between oil-water and air-water interfaces. FINDINGS: The EDGE tensiometer can measure at timescales down to a few milliseconds and up to around 10 s, while the ADT provides dynamic interfacial tension values after at least one second from droplet injection and typically is used to also cover hours. The interfacial tension values measured with both techniques exhibit overlap, implying that the techniques provide consistent and complementary information. Unlike the ADT, the EDGE tensiometer distinguishes differences in protein adsorption dynamics at protein concentrations as high as 10 wt% (which is the highest concentration tested) at both oil-water and air-water interfaces.


Assuntos
Tensão Superficial , Água , Proteínas do Soro do Leite , Adsorção , Proteínas do Soro do Leite/química , Água/química , Ar , Alcanos/química , Óleos/química , Tamanho da Partícula , Propriedades de Superfície , Técnicas Analíticas Microfluídicas/instrumentação
6.
Brain Commun ; 6(4): fcae199, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38993284

RESUMO

Alzheimer's disease is characterized by cognitive impairment and progressive brain atrophy. Recent human neuroimaging studies reported atypical anatomical and functional changes in some regions in the default mode network in patients with Alzheimer's disease, but which brain area of the default mode network is the key region whose atrophy disturbs the entire network activity and consequently contributes to the symptoms of the disease remains unidentified. Here, in this case-control study, we aimed to identify crucial neural regions that mediated the phenotype of Alzheimer's disease, and as such, we examined the intrinsic neural timescales-a functional metric to evaluate the capacity to integrate diverse neural information-and grey matter volume of the regions in the default mode network using resting-state functional MRI images and structural MRI data obtained from individuals with Alzheimer's disease and cognitively typical people. After confirming the atypically short neural timescale of the entire default mode network in Alzheimer's disease and its link with the symptoms of the disease, we found that the shortened neural timescale of the default mode network was associated with the aberrantly short neural timescale of the left angular gyrus. Moreover, we revealed that the shortened neural timescale of the angular gyrus was correlated with the atypically reduced grey matter volume of this parietal region. Furthermore, we identified an association between the neural structure, brain function and symptoms and proposed a model in which the reduced grey matter volume of the left angular gyrus shortened the intrinsic neural time of the region, which then destabilized the entire neural timescale of the default mode network and resultantly contributed to cognitive decline in Alzheimer's disease. These findings highlight the key role of the left angular gyrus in the anatomical and functional aetiology of Alzheimer's disease.

7.
Environ Sci Pollut Res Int ; 31(25): 37283-37297, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38772992

RESUMO

The dynamic subsidence disaster caused by underground mining of coal resources is a complex spatiotemporal process, which is a common disaster in mining areas. The backfilling strip mining technology is a green and sustainable coal mining method, which has been commonly used to reduce the subsidence disaster of the overlying strata and protect surface buildings. The transient deformation is the main reason of surface buildings damage; therefore, in this study, the similar material model was used to research dynamic deformation characteristics of the overlying strata in backfilling strip mining at different time scales, and the optical image method was employed to monitor and obtain the movement data of the overlying strata automatically. The data analysis shows that there is a time-scale effect in mining subsidence. The deformation of the overlying strata increases instantaneously at a certain time under the monitoring of small time scale, and this phenomenon gradually disappears as time scales increase. According to the subsidence velocity of small time scale, the subsidence state of the overlying strata can be further divided into the abrupt subsidence state and the gentle subsidence state. This is really significant for promoting the development of the backfilling strip mining technology and preventing the damage of surface buildings.


Assuntos
Minas de Carvão , Mineração , Carvão Mineral
8.
Proc Natl Acad Sci U S A ; 121(21): e2317781121, 2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38758700

RESUMO

Complex networks are pervasive in various fields such as chemistry, biology, and sociology. In chemistry, first-order reaction networks are represented by a set of first-order differential equations, which can be constructed from the underlying energy landscape. However, as the number of nodes increases, it becomes more challenging to understand complex kinetics across different timescales. Hence, how to construct an interpretable, coarse-graining scheme that preserves the underlying timescales of overall reactions is of crucial importance. Here, we develop a scheme to capture the underlying hierarchical subsets of nodes, and a series of coarse-grained (reduced-dimensional) rate equations between the subsets as a function of time resolution from the original reaction network. Each of the coarse-grained representations guarantees to preserve the underlying slow characteristic timescales in the original network. The crux is the construction of a lumping scheme incorporating a similarity measure in deciphering the underlying timescale hierarchy, which does not rely on the assumption of equilibrium. As an illustrative example, we apply the scheme to four-state Markovian models and Claisen rearrangement of allyl vinyl ether (AVE), and demonstrate that the reduced-dimensional representation accurately reproduces not only the slowest but also the faster timescales of overall reactions although other reduction schemes based on equilibrium assumption well reproduce the slowest timescale but fail to reproduce the second-to-fourth slowest timescales with the same accuracy. Our scheme can be applied not only to the reaction networks but also to networks in other fields, which helps us encompass their hierarchical structures of the complex kinetics over timescales.

9.
J Neural Eng ; 21(2)2024 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-38565132

RESUMO

Objective.Understanding the intricate relationship between structural connectivity (SC) and functional connectivity (FC) is pivotal for understanding the complexities of the human brain. To explore this relationship, the heat diffusion model (HDM) was utilized to predict FC from SC. However, previous studies using the HDM have typically predicted FC at a critical time scale in the heat kernel equation, overlooking the dynamic nature of the diffusion process and providing an incomplete representation of the predicted FC.Approach.In this study, we propose an alternative approach based on the HDM. First, we introduced a multiple-timescale fusion method to capture the dynamic features of the diffusion process. Additionally, to enhance the smoothness of the predicted FC values, we employed the Wavelet reconstruction method to maintain local consistency and remove noise. Moreover, to provide a more accurate representation of the relationship between SC and FC, we calculated the linear transformation between the smoothed FC and the empirical FC.Main results.We conducted extensive experiments in two independent datasets. By fusing different time scales in the diffusion process for predicting FC, the proposed method demonstrated higher predictive correlation compared with method considering only critical time points (Singlescale). Furthermore, compared with other existing methods, the proposed method achieved the highest predictive correlations of 0.6939±0.0079 and 0.7302±0.0117 on the two datasets respectively. We observed that the visual network at the network level and the parietal lobe at the lobe level exhibited the highest predictive correlations, indicating that the functional activity in these regions may be closely related to the direct diffusion of information between brain regions.Significance.The multiple-timescale fusion method proposed in this study provides insights into the dynamic aspects of the diffusion process, contributing to a deeper understanding of how brain structure gives rise to brain function.


Assuntos
Conectoma , Humanos , Conectoma/métodos , Temperatura Alta , Encéfalo , Imagem de Tensor de Difusão/métodos , Lobo Parietal , Imageamento por Ressonância Magnética/métodos
10.
Water Environ Res ; 96(5): e11031, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38685725

RESUMO

The pollutant transport equilibrium in a watershed can be analyzed on a large time scale, and land-use export coefficients can be calculated directly under certain hydrologic and transport conditions, by ignoring hydrologic and transport processes at small space and time scales on hydrologic response units. In this study, the water environment system of a watershed was deconstructed into three parts (source, source-sink, and runoff transport) to construct a pollutant transportation equilibrium model on a large time scale. A watershed with an annual source-sink accumulation of zero was defined as a completely transported watershed; therefore, we derived a completely transported equilibrium equation. The problem of seeking the land export coefficient was converted into a problem of seeking the optimal solution of linear programming, which can be estimated according to the variation in pollutant output processes. The feasibility of the solution can be analyzed using multi-year stochastic rainfall processes. The model was used to analyze the transport equilibrium of chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) upstream of the monitored cross-sections in a watershed, which covered 3145.66 km2. The land export coefficients were calculated according to the model. The model calculations indicated that the watershed was completely transported during perennial years. The calculated export coefficients of COD, TN, and TP for farmland, primary vegetation, and urban land were within the range of general empirical values. The calculated maximum accumulations of COD, TN, and TP were 0.19 × 107, 0.063 × 107, and 0.049 × 106 kg, respectively, for perennial rainfall. PRACTITIONER POINTS: A completely transported watershed was defined, and a model of pollutant transportation equilibrium with large time-scale was constructed. A problem of seeking the optimal solution of a linear programming was designed to estimate the land export coefficient of COD, TN, and TP. The runoff transport and accumulation processes of COD, TN, and TP in a watershed was analyzed.


Assuntos
Modelos Teóricos , Movimentos da Água , Poluentes Químicos da Água , Poluentes Químicos da Água/química , Fósforo/química , Nitrogênio/química , Monitoramento Ambiental , Análise da Demanda Biológica de Oxigênio
11.
Water Res ; 254: 121385, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38452525

RESUMO

The Yangtze River is the third longest river in the world with more than 6300 km, covering 0.4 billion people. However, the aquatic ecosystem of the Yangtze River has been seriously damaged in the past decades due to a rapid development of economic and industrialization along the coast. In this study, we first established a dataset of fifty elements, including nine common heavy metals (HMs) and forty-one other elements, in the Yangtze River Basin through the collection of historical data from 2000 to 2020, and then analyzed their spatiotemporal distribution characteristics. The results indicated that the Three Gorges Reservoir (TGR), a region formed by the construction of the Three Gorges Dam (TGD), may act as a sink for these elements from upstream regions. The concentrations of seven elements in surface water and 13 elements in sediment obviously increased from the upstream region of the TGR to the TGR. In addition, ten elements in the surface water and 5 elements in the sediments clearly decreased, possibly because of the interception effects of the TGD. On a timescale, Cr obviously tended to migrate from the water phase to the sediment; Pb tended to migrate from the sediment to the water phase. In the ecological risk assessment, all common HMs in surface water were supposed to have negligible risks as protecting 90 % of aquatic organisms; Cd (210.2), Hg (58.0) and As (43.1) in sediment posed high and moderate ecological risks using the methodology of the potential ecological risk index. Furthermore, Hunan Province is at considerable risk according to the sum of the potential risk index (314.8) due to Cd pollution (66.8 %). These fundamental data and results will support follow-up control strategies for elements and policies related to aquatic ecosystem protection in the Yangtze River Basin.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Humanos , Ecossistema , Rios , Cádmio/análise , Estudos Retrospectivos , Monitoramento Ambiental , Poluentes Químicos da Água/análise , Sedimentos Geológicos , Metais Pesados/análise , Medição de Risco , Água/análise , China
12.
Front Hum Neurosci ; 18: 1362135, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38505099

RESUMO

Introduction: Brain-computer interfaces (BCIs) are systems that acquire the brain's electrical activity and provide control of external devices. Since electroencephalography (EEG) is the simplest non-invasive method to capture the brain's electrical activity, EEG-based BCIs are very popular designs. Aside from classifying the extremity movements, recent BCI studies have focused on the accurate coding of the finger movements on the same hand through their classification by employing machine learning techniques. State-of-the-art studies were interested in coding five finger movements by neglecting the brain's idle case (i.e., the state that brain is not performing any mental tasks). This may easily cause more false positives and degrade the classification performances dramatically, thus, the performance of BCIs. This study aims to propose a more realistic system to decode the movements of five fingers and the no mental task (NoMT) case from EEG signals. Methods: In this study, a novel praxis for feature extraction is utilized. Using Proper Rotational Components (PRCs) computed through Intrinsic Time Scale Decomposition (ITD), which has been successfully applied in different biomedical signals recently, features for classification are extracted. Subsequently, these features were applied to the inputs of well-known classifiers and their different implementations to discriminate between these six classes. The highest classifier performances obtained in both subject-independent and subject-dependent cases were reported. In addition, the ANOVA-based feature selection was examined to determine whether statistically significant features have an impact on the classifier performances or not. Results: As a result, the Ensemble Learning classifier achieved the highest accuracy of 55.0% among the tested classifiers, and ANOVA-based feature selection increases the performance of classifiers on five-finger movement determination in EEG-based BCI systems. Discussion: When compared with similar studies, proposed praxis achieved a modest yet significant improvement in classification performance although the number of classes was incremented by one (i.e., NoMT).

13.
Hum Brain Mapp ; 45(2): e26587, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38339903

RESUMO

Recent years have seen growing interest in characterizing the properties of regional brain dynamics and their relationship to other features of brain structure and function. In particular, multiple studies have observed regional differences in the "timescale" over which activity fluctuates during periods of quiet rest. In the cerebral cortex, these timescales have been associated with both local circuit properties as well as patterns of inter-regional connectivity, including the extent to which each region exhibits widespread connectivity to other brain areas. In the current study, we build on prior observations of an association between connectivity and dynamics in the cerebral cortex by investigating the relationship between BOLD fMRI timescales and the modular organization of structural and functional brain networks. We characterize network community structure across multiple scales and find that longer timescales are associated with greater within-community functional connectivity and diverse structural connectivity. We also replicate prior observations of a positive correlation between timescales and structural connectivity degree. Finally, we find evidence for preferential functional connectivity between cortical areas with similar timescales. We replicate these findings in an independent dataset. These results contribute to our understanding of functional brain organization and structure-function relationships in the human brain, and support the notion that regional differences in cortical dynamics may in part reflect the topological role of each region within macroscale brain networks.


Assuntos
Encéfalo , Córtex Cerebral , Humanos , Encéfalo/diagnóstico por imagem , Córtex Cerebral/diagnóstico por imagem , Mapeamento Encefálico/métodos , Imageamento por Ressonância Magnética , Descanso , Rede Nervosa/diagnóstico por imagem
14.
Sci Total Environ ; 917: 170249, 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38278251

RESUMO

An effective drought monitoring tool is essential for the development of timely drought early warning system. This study evaluates Evaporative Demand Drought Index (EDDI) as a drought indicator in measuring spatiotemporal evolution of droughts over Peninsular Malaysia during 1989-2018. The modified Mann-Kendall and Sen's slope tests were performed to detect the presence of monotonic trends in EDDI, Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI) and their related climate variables. The performance of EDDI in capturing the drought onset, evolutions and demise of historical severe droughts was also compared with SPI and SPEI at multiple timescales. EDDI demonstrates strong spatiotemporal correlations with SPI and SPEI and comparable performance in historical drought events identification. At sub-monthly timescale, 2-week EDDI displays equivalent drought severities and durations for all historical severe droughts corresponding to the monthly EDDI. In the case when rainfall deficits are normalized in an otherwise warm and dry month, EDDI may serve as a great alternative to SPI and SPEI due to it being sensitive to the changes in prevalent atmospheric conditions. Collectively, the results fill in the knowledge gaps on drought evolutions from the evaporative perspective and highlight the efficacy of EDDI as a valuable drought early warning tool for Peninsular Malaysia. Future study should explore the physical mechanisms behind the development of flash drought and the role of evaporation in the drought propagation processes.

15.
mSystems ; 9(2): e0100123, 2024 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-38259168

RESUMO

Understanding the dynamics of biological systems in evolving environments is a challenge due to their scale and complexity. Here, we present a computational framework for the timescale decomposition of biochemical reaction networks to distill essential patterns from their intricate dynamics. This approach identifies timescale hierarchies, concentration pools, and coherent structures from time-series data, providing a system-level description of reaction networks at physiologically important timescales. We apply this technique to kinetic models of hypothetical and biological pathways, validating it by reproducing analytically characterized or previously known concentration pools of these pathways. Moreover, by analyzing the timescale hierarchy of the glycolytic pathway, we elucidate the connections between the stoichiometric and dissipative structures of reaction networks and the temporal organization of coherent structures. Specifically, we show that glycolysis is a cofactor-driven pathway, the slowest dynamics of which are described by a balance between high-energy phosphate bond and redox trafficking. Overall, this approach provides more biologically interpretable characterizations of network dynamics than large-scale kinetic models, thus facilitating model reduction and personalized medicine applications. IMPORTANCE Complex interactions within interconnected biochemical reaction networks enable cellular responses to a wide range of unpredictable environmental perturbations. Understanding how biological functions arise from these intricate interactions has been a long-standing problem in biology. Here, we introduce a computational approach to dissect complex biological systems' dynamics in evolving environments. This approach characterizes the timescale hierarchies of complex reaction networks, offering a system-level understanding at physiologically relevant timescales. Analyzing various hypothetical and biological pathways, we show how stoichiometric properties shape the way energy is dissipated throughout reaction networks. Notably, we establish that glycolysis operates as a cofactor-driven pathway, where the slowest dynamics are governed by a balance between high-energy phosphate bonds and redox trafficking. This approach enhances our understanding of network dynamics and facilitates the development of reduced-order kinetic models with biologically interpretable components.


Assuntos
Fenômenos Fisiológicos Celulares , Glicólise , Cinética , Fosfatos
16.
J Theor Biol ; 581: 111731, 2024 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-38211891

RESUMO

The poor maintenance of eating behavior change is one of the main obstacles to minimizing weight regain after weight loss during diets for non-surgical care of obese or overweight patients. We start with a known informal explanation of interruption in eating behavior change during severe restriction and formalize it as a causal network involving psychological variables, which we extend with energetic variables governed by principles of thermodynamics. The three core phenomena of dietary behavior change, i.e., non-initiation, initiation followed by discontinuation and initiation followed by non-discontinuation, are expressed in terms of the value of the key variable representing mood or psychological energy, the fluctuation of which is the result of three causal relationships. Based on our experimental knowledge of the time evolution profile of the three causal input variables, we then proceed to a qualitative analysis of the resulting theory, i.e., we consider an over-approximation of it which, after discretization, can be expressed in the form of a finite integer-based model. Using Answer Set Programming, we show that our formal model faithfully reproduces the three phenomena and, under a certain assumption, is minimal. We generalize this result by providing all the minimal models reproducing these phenomena when the possible causal relationships exerted on mood are extended to all the other variables (not just those assumed in the informal explanation), with arbitrary causality signs. Finally, by a direct analytical resolution of an under-approximation of our theory, obtained by assuming linear causalities, as a system of linear ODEs, we find exactly the same minimal models, proving that they are also equal to the actual minimal models of our theory since these are framed below and above by the models of the under-approximation and the over-approximation. We determine which parameters need to be person-specific and which can be considered invariant, i.e., we explain inter-individual variability. Our approach could pave the way for universally accepted theories in the field of behavior change and, more broadly, in other areas of psychology.


Assuntos
Comportamento Alimentar , Obesidade , Humanos
17.
Adv Sci (Weinh) ; 11(5): e2304122, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38059830

RESUMO

Diffusion in alloys is an important class of atomic processes. However, atomistic simulations of diffusion in chemically complex solids are confronted with the timescale problem: the accessible simulation time is usually far shorter than that of experimental interest. In this work, long-timescale simulation methods are developed using reinforcement learning (RL) that extends simulation capability to match the duration of experimental interest. Two special limits, RL transition kinetics simulator (TKS) and RL low-energy states sampler (LSS), are implemented and explained in detail, while the meaning of general RL are also discussed. As a testbed, hydrogen diffusivity is computed using RL TKS in pure metals and a medium entropy alloy, CrCoNi, and compared with experiments. The algorithm can produce counter-intuitive hydrogen-vacancy cooperative motion. We also demonstrate that RL LSS can accelerate the sampling of low-energy configurations compared to the Metropolis-Hastings algorithm, using hydrogen migration to copper (111) surface as an example.

18.
Neural Netw ; 169: 83-91, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37864998

RESUMO

In this paper, we propose a two-timescale projection neural network (PNN) for solving optimization problems with nonconvex functions. We prove the convergence of the PNN with sufficiently different timescales to a local optimal solution. We develop a collaborative neurodynamic approach with multiple such PNNs to search for global optimal solutions. In addition, we develop a collaborative neurodynamic approach with multiple PNNs connected via a directed graph for distributed global optimization. We elaborate on four numerical examples to illustrate the characteristics of the approaches.


Assuntos
Redes Neurais de Computação , Resolução de Problemas
19.
Adv Healthc Mater ; 13(7): e2302810, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37992675

RESUMO

Effective wound healing is critical for patient care, and the development of novel wound dressing materials that promote healing, prevent infection, and are user-friendly is of great importance, particularly in the context of point-of-care testing (POCT). This study reports the synthesis of a hydrogel material that can be produced in less than 10 s and possesses antibacterial activity against both gram-negative and gram-positive microorganisms, as well as the ability to inhibit the growth of eukaryotic cells, such as yeast. The hydrogel is formed wholly based on covalent-like hydrogen bonding interactions and exhibits excellent mechanical properties, with the ability to stretch up to more than 600% of its initial length. Furthermore, the hydrogel demonstrates ultra-fast self-healing properties, with fractures capable of being repaired within 10 s. This hydrogel can promote skin wound healing, with the added advantage of functioning as a strain sensor that generates an electrical signal in response to physical deformation. The strain sensor composed of a rubber shell realizes fast and responsive strain sensing. The findings suggest that this hydrogel has promising applications in the field of POCT for wound care, providing a new avenue for improved patient outcomes.


Assuntos
Hidrogéis , Lesões dos Tecidos Moles , Humanos , Pele , Epiderme , Antibacterianos
20.
J Magn Reson Imaging ; 59(3): 987-995, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37318377

RESUMO

BACKGROUND: Numerous studies have indicated altered temporal features of the brain function in Parkinson's disease (PD), and the autocorrelation magnitude of intrinsic neural signals, called intrinsic neural timescales, were often applied to estimate how long neural information stored in local brain areas. However, it is unclear whether PD patients at different disease stages exhibit abnormal timescales accompanied with abnormal gray matter volume (GMV). PURPOSE: To assess the intrinsic timescale and GMV in PD. STUDY TYPE: Prospective. POPULATION: 74 idiopathic PD patients (44 early stage (PD-ES) and 30 late stage (PD-LS), as determined by the Hoehn and Yahr (HY) severity classification scale), and 73 healthy controls (HC). FIELD STRENGTH/SEQUENCE: 3.0 T MRI scanner; magnetization prepared rapid acquisition gradient echo and echo planar imaging sequences. ASSESSMENT: The timescales were estimated by using the autocorrelation magnitude of neural signals. Voxel-based morphometry was performed to calculate GMV in the whole brain. Severity of motor symptoms and cognitive impairments were assessed using the unified PD rating scale, the HY scale, the Montreal cognitive assessment, and the mini-mental state examination. STATISTICAL TEST: Analysis of variance; two-sample t-test; Spearman rank correlation analysis; Mann-Whitney U test; Kruskal-Wallis' H test. A P value <0.05 was considered statistically significant. RESULTS: The PD group had significantly abnormal intrinsic timescales in the sensorimotor, visual, and cognitive-related areas, which correlated with the symptom severity (ρ = -0.265, P = 0.022) and GMV (ρ = 0.254, P = 0.029). Compared to the HC group, the PD-ES group had significantly longer timescales in anterior cortical regions, whereas the PD-LS group had significantly shorter timescales in posterior cortical regions. CONCLUSION: This study suggested that PD patients have abnormal timescales in multisystem and distinct patterns of timescales and GMV in cerebral cortex at different disease stages. This may provide new insights for the neural substrate of PD. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 1.


Assuntos
Substância Cinzenta , Doença de Parkinson , Humanos , Doença de Parkinson/complicações , Estudos Prospectivos , Córtex Cerebral , Imageamento por Ressonância Magnética/métodos
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