Differences In Network Parameters Research Articles

Fire and Rhizosphere Effects on Bacterial Co-Occurrence Patterns

Fires are common in Mediterranean soils and constitute an important driver of their evolution. Although fire effects on vegetation dynamics are widely studied, their influence on the assembly rules of soil prokaryotes in a small-scale environment has attracted limited attention. In the present study, we reanalyzed the data from Aponte et al. (2022) to test whether the direct and/or indirect effects of fire are reflected in the network of relationships among soil prokaryotes in a Chilean sclerophyllous ecosystem. We focused on bacterial (genus and species level) co-occurrence patterns in the rhizospheres and bulk soils in burned and unburned plots. Four soils were considered: bulk-burnt (BB), bulk-unburnt (BU), rhizosphere-burnt (RB), and rhizosphere-unburnt (RU). The largest differences in network parameters were recorded between RU and BB soils, while RB and BU networks exhibited similar values. The network in the BB soil was the most compact and centralized, while the RU network was the least connected, with no central nodes. The robustness of bacterial communities was enhanced in burnt soils, but this was more pronounced in BB soil. The mechanisms mainly responsible for bacterial community structure were stochastic in all soils, whether burnt or unburnt; however, communities in RB were much more stochastic than in RU.

A Network Analysis of Executive Functions in Children and Adolescents With and Without Attention-Deficit/Hyperactivity Disorder.

This study applied network analysis to executive function test performances to examine differences in network parameters between demographically matched children and adolescents with and without attention-deficit/hyperactivity disorder (ADHD) (n = 141 per group; M = 12.7 ± 2.9years-old; 72.3% boys, 66.7% White, 65.2% ≥ 12years maternal education). All participants completed the NIH Toolbox Cognition Battery, including the Flanker, measuring inhibition, Dimensional Change Card Sort, measuring shifting, and List Sorting test, measuring working memory. Children with and without ADHD had comparable mean test performances (d range: .05-0.11) but presented with differences in network parameters. Among participants with ADHD, shifting was less central, had a weaker relationship with inhibition, and did not mediate the relationship between inhibition and working memory. These network characteristics were consistent with the executive function network structure of younger ages in prior research and may reflect an immature executive function network among children and adolescents with ADHD, aligning with the delayed maturation hypothesis.

Signal quality as Achilles\u2019 heel of graph theory in functional magnetic resonance imaging in multiple sclerosis

Graph-theoretical analysis is a novel tool to understand the organisation of the brain.We assessed whether altered graph theoretical parameters, as observed in multiple sclerosis (MS), reflect pathology-induced restructuring of the brain's functioning or result from a reduced signal quality in functional MRI (fMRI). In a cohort of 49 people with MS and a matched group of 25 healthy subjects (HS), we performed a cognitive evaluation and acquired fMRI. From the fMRI measurement, Pearson correlation-based networks were calculated and graph theoretical parameters reflecting global and local brain organisation were obtained. Additionally, we assessed metrics of scanning quality (signal to noise ratio (SNR)) and fMRI signal quality (temporal SNR and contrast to noise ratio (CNR)). In accordance with the literature, we found that the network parameters were altered in MS compared to HS. However, no significant link was found with cognition. Scanning quality (SNR) did not differ between both cohorts. In contrast, measures of fMRI signal quality were significantly different and explained the observed differences in GTA parameters. Our results suggest that differences in network parameters between MS and HS in fMRI do not reflect a functional reorganisation of the brain, but rather occur due to reduced fMRI signal quality.

Multiplex Recurrence Network Analysis of Inter-Muscular Coordination During Sustained Grip and Pinch Contractions at Different Force Levels

Production of functional forces by human motor systems require coordination across multiple muscles. Grip and pinch are two prototypes for grasping force production. Each grasp plays a role in a range of hand functions and can provide an excellent paradigm for studying fine motor control. Despite previous investigations that have characterized muscle synergies during general force production, it is still unclear how intermuscular coordination differs between grip and pinch and across different force outputs. Traditional muscle synergy analyses, such as non-negative matrix factorization or principal component analysis, utilize dimensional reduction without consideration of nonlinear characteristics of muscle co-activations. In this study, we investigated the novel method of multiplex recurrence networks (MRN) to assess the inter-muscular coordination for both grip and pinch at different force levels. Unlike traditional methods, the MRN can leverage intrinsic similarities in muscle contraction dynamics and project its layers to the corresponding weighted network (WN) to better model muscle interactions. Twenty-four healthy volunteers were instructed to grip and pinch an apparatus with force production at 30%, 50%, and 70% of their respective maximal voluntary contraction (MVC). The surface electromyography (sEMG) signals were recorded from eight muscles, including intrinsic and extrinsic muscles spanning the hand and forearm. The sEMG signals were then analyzed using MRNs and WNs. Interlayer mutual information ( I ) and average edge overlap ( ω ) of MRNs and average shortest path length ( L ) of WNs were computed and compared across groups for grasp types (grip vs. pinch) and force levels (30%, 50% and 70% MVC). Results showed that the extrinsic, rather than the intrinsic muscles, had significant differences in network parameters between both grasp types ( ), and force levels ( ), and especially at higher force levels. Furthermore, I and ω were strengthened over time ( ) except with pinch at 30% MVC. Results suggest that the central nervous system (CNS) actively increases cortical oscillations over time in response to increasing force levels and changes in force production with different sustained grasping types. Muscle coupling in extrinsic muscles was higher than in intrinsic muscles for both grip and pinch. The MRNs may be a valuable tool to provide greater insights into inter-muscular coordination patterns of clinical populations, assess neuromuscular function, or stabilize force control in prosthetic hands.

Altered structural networks in neuromyelitis optica spectrum disorder related with cognition impairment and clinical features

ObjectiveTo investigate the topological properties alterations of white matter (WM) network in neuromyelitis optica spectrum disorder (NMOSD) patients and its correlation with clinical and cognitive performance. MethodsForty-eight NMOSD patients and fifty healthy controls (HC) underwent DTI and 3D-T1 scan on a 3.0 T MRI and clinical data and cognitive scales were collected. Structural networks were constructed and analyzed by using graph theory. The network metrics between-group comparisons were examined by using GRETNA. Differences in network parameters between two groups and grouped patients according to disease duration (DD) were compared to examine the impact of DD on WM network. The relationships between the network characteristics and clinical data and cognitive performances were also analyzed by partial correlation analysis. ResultsThe NMOSD patients exhibited decreased global and local network efficiency and increased characteristic path length, which were pronounced more in long DD patients. Furthermore, altered nodal efficiencies were observed in several brain regions, which were mainly distributed in default mode and visual systems. The Expanded Disability Status Scale was positively related to nodal shortest path. NMOSD patients showed decreased cognitive performance in attention, short-term memory and verbal memory, which were associated with significantly decreased degree centrality, nodal efficiency and increased nodal shortest path of several brain regions (all p<0.05). ConclusionsThis study illustrated the relationship between WM disruption and cognitive impairment in NMOSD patients, which advance the understanding of disrupted WM networks and provide insight into subtle WM pathology to cognitive impairment in NMOSD.

Performance Analysis of Edge Computing in IoT

Upcoming 5G technology and the demand for near real-time response services raise the need for optimizing current IoT solutions. The aim of this paper is to model and execute the performance analysis of network structures suitable for Edge Computing in IoT. The prior research into different topology and parameter sets have not provided sufficient clarity, on which parameters had a considerable impact on overall system performance; therefore, repetitive simulations were performed to express dispersion of alternating values, as well as determining its confidence intervals. The paper presents Edge Computing service simulation setup on known and newly derived network topologies with different complexity varying network bandwidth and network delay parameters. The experimental investigation has revealed that the IoT configuration network is more sensitive to network topology, while the Internet configuration is more sensitive to network parameters. The discussion on the results received debates possible causes of performance differences in network parameters and device configurations, the comparison to similar state-of-the-art research results has also been presented. Finally, conclusions with recommendations based on the results acquired have been provided.

Effect of Temporal Lobe Epilepsy on Auditory-motor Integration for Vocal Pitch Regulation: Evidence from Brain Functional Network Analysis.

Temporal lobe epilepsy (TLE) is a medically refractory focal epilepsy associated with structural deficits. Considerable evidence has revealed that patients with TLE also exhibit deficits in functional connectivity. According to previous research, patients with TLE exhibited decreased performance in speech sound perception and auditory-motor integration for voice control, which might be related to the compromised brain network connectivity. However, the specific nature of functional connectivity within and across brain regions remains largely unknown. To answer this question, we extended previous research from examining the topological properties of the entire brain network to the intra- and inter-regional communications of different brain regions. Patients with TLE and healthy controls were recruited to perform a pitch reflex task, during which electroencephalograph (EEG) data were acquired to construct graphical brain networks. Compared with healthy controls, inter-regional and cross-hemispheric connections were reduced in patients with TLE, whose functional networks were primarily composed of intra-regional connections. Significant differences in network parameters (betweenness centrality, modularity, and functional integration) as well as network hubs between the two groups further supported our findings that TLE is associated with alterations in functional connectivity during auditory-motor integration.

Intra- and Inter-Modular Connectivity Alterations in the Brain Structural Network of Spinocerebellar Ataxia Type 3.

In addition to cerebellar degeneration symptoms, patients with spinocerebellar ataxia type 3 (SCA3) exhibit extensive involvements with damage in the prefrontal cortex. A network model has been proposed for investigating the structural organization and functional mechanisms of clinical brain disorders. For neural degenerative diseases, a cortical feature-based structural connectivity network can locate cortical atrophied regions and indicate how their connectivity and functions may change. The brain network of SCA3 has been minimally explored. In this study, we investigated this network by enrolling 48 patients with SCA3 and 48 healthy subjects. A novel three-dimensional fractal dimension-based network was proposed to detect differences in network parameters between the groups. Copula correlations and modular analysis were then employed to categorize and construct the structural networks. Patients with SCA3 exhibited significant lateralized atrophy in the left supratentorial regions and significantly lower modularity values. Their cerebellar regions were dissociated from higher-level brain networks, and demonstrated decreased intra-modular connectivity in all lobes, but increased inter-modular connectivity in the frontal and parietal lobes. Our results suggest that the brain networks of patients with SCA3 may be reorganized in these regions, with the introduction of certain compensatory mechanisms in the cerebral cortex to minimize their cognitive impairment syndrome.

Investigating the correlation between crystallized IQ and network metrics in cerebellum using resting-state fMRI

Investigating the correlation between crystallized IQ and network metrics in cerebellum using resting-state fMRI

Network analysis of transmembrane protein structures

Most studies have shown that globular proteins exist in small-world networks. The present study is an attempt to determine differences in network parameters between transmembrane and globular proteins. Each protein is represented as an undirected graph, where residues represent nodes and inter-residue interactions as the edges. This was then compared to the degree-preserved random controls, to observe if any variation existed. Results indicate that there is a significant difference in shortest path lengths between transmembrane and globular proteins. Hydrophobic amino acids were found to be more spatially distributed in the transmembrane than in globular proteins causing significantly higher values of shortest path lengths (L). Assortativity values too, were found to be significantly higher in the transmembrane than in globular proteins which is due to the highly connected amino acid residues being exposed to the solvent in transmembrane proteins. On analyzing the closeness centrality, it was found that globular proteins have significantly higher values than the transmembrane proteins. We therefore conclude that transmembrane proteins possess small-world characteristics similar to that of globular proteins.

Development and Optimization of Fast Quantitative Carbon-13 NMR Characterization Methods of Novolac Resins

An improved 13 C NMR quantification technique of random and high-ortho novolacs in THF-CDCl 3 solutions is reported. Full quantitative spectra of phenol formaldehyde resins with high signal-to-noise ratios are obtained by using chromium acetylacetonate under optimized spectral conditions within a few hours of spectrometer time. Attached proton test (APT) spectra were acquired to enable proper peak assignments in the region with significant overlap. For several novolacs, prepared under different catalytic conditions, the degree of polymeization, degree of branching, number average molecular weight, isomeric distribution, and number of unreacted ortho and para phenoling positions could accurately be determined. The improved quantification method and the use of the aromatic instead of the aliphatic region permitted to measure for the first time small differences in network parameters for comparable novolac samples