Network Connectance Research Articles

Patterns in the predator–prey system with network connection and harvesting policy

A diffusive predator–prey system with the network connection and harvesting policy is investigated in the present paper. The global existence and boundedness of the positive solutions to the parabolic equations are analyzed. Hereafter, a priori estimates and non‐existence of the non‐constant steady states are investigated for the corresponding elliptic equation. Next, we focus on the network connect model. The stability of the positive equilibrium, the Hopf bifurcation, and the Turing instability of networked system are explored. By using the multiple time scale (MTS), the direction of the Hopf bifurcation is determined. It is found that the networked system may admit a supercritical or subcritical Hopf bifurcation. For the Turing instability, the positive equilibrium will change its stability from an unstable state to a stable one with the change of the connecting probability. That is not the case in the model without network structure. Theoretical results also show that the model can create rich dynamical behaviors and numerical simulations well verify the validity of the theoretical analysis.

Network Structure of Bat-Ectoparasitic Interactions in Tropical Dry Forests at Two Different Regions in Brazil

Network analysis has been used for understanding complex systems in biology for decades. However, scant information is available for networks of antagonistic interactions. The aim of this study was to describe and compare bat-ectoparasite interaction networks in tropical dry forests (TFDs) in the Brazilian Cerrado and Caatinga biomes, which have contrasting environmental conditions and surrounding matrix. Bats and ectoparasites were sampled at six sites in northern and central Minas Gerais State, southeast Brazil. Network connectance, nestedness and number of compartments were compared between regions, as well as bat species richness, abundance and centrality, and ectoparasite specialization. The effect of bat phylogenetic relatedness on the similarity of their associated ectoparasite species was also tested. Bat-ectoparasite networks were nested, connected and highly compartmentalized in TDFs from both regions, with no significant differences in network structure. In addition, host species richness negatively influenced nestedness and connectance, but was positively related to compartment number. These findings are likely related to the high specialization observed for bat-fly species (usually one exclusive parasite species per host), resulting in networks with few interactions. Bat abundance positively affected bat-fly richness, indicating that resource availability is important in determining host-parasite relationships. Finally, phylogenetically related species of bats possessed more similar ectoparasite faunas, which may be associated with evolutionary responses of ectoparasites to escape defensive mechanisms of different bat species. Our results suggest that local bat-ectoparasite interactions are influenced by both ecological factors and evolutionary constraints, but the effects of environmental conditions on network topology deserved further detailed studies.

Linking the network topology of plant traits with community structure, functioning, and adaptive strategies of submerged macrophytes

Plant trait network analysis can calculate the topology of trait correlations and clarify the complex relationships among traits, providing new insights into ecological topics, including trait dimensions and phenotypic integration. However, few studies have focused on the relationships between network topology and community structure, functioning, and adaptive strategies, especially in natural submerged macrophyte communities. In this study, we collected 15 macrophyte community-level traits from 12 shallow lakes in the Yangtze River Basin in the process of eutrophication and analyzed the changes in trait network structure (i.e., total phosphorus, TP) by using a moving window method. Our results showed that water TP significantly changed the topology of trait networks. Specifically, under low or high nutrient levels, the network structure was more dispersed, with lower connectance and higher modularity than that found at moderate nutrient levels. We also found that network connectance was positively correlated with community biomass and homeostasis, while network modularity was negatively correlated with community biomass and homeostasis. In addition, modules and hub traits also changed with the intensity of eutrophication, which can reflect the trait integration and adaptation strategies of plants in a stressful environment. At low or high nutrient levels, more modules were differentiated, and those modules with higher strength were related to community nutrition. Our results clarified the dynamics of community structure and functioning from a new perspective of plant trait networks, which is key to predicting the response of ecosystems to environmental changes.

Historic and Contemporary Land Use Shape Plant-Pollinator Networks and Community Composition

Globally, grasslands represent a critical but shrinking habitat for native plants and pollinators, with declines driven by alterations to landscape-scale habitat cover and local-scale disturbance regimes, among other factors. Specifically, as cities expand in size, an increasing proportion of regional pasture and grassland habitat is being replaced by urban development, and fewer periodic grazing and burning regimes are being supported locally, despite evidence that such regimes promote plant species richness and facilitate their interaction with native pollinators. The quantification of these plant-pollinator networks—through indices such as network connectance, specialization, nestedness, and robustness—can provide a unique opportunity to characterize key structural properties of species interactions and their response to human management and seasonal phenology. While urbanization and local disturbance regimes likely influence plant and pollinator communities and their interactions, past research in this area has primarily been conducted at limited spatial and temporal scales and has not typically quantified the impacts of both local and landscape forces on network properties. In this study, we investigate the effects of contemporary (past 10 years) and historic (prior 90 years) disturbance regimes on plant-pollinator community composition and network structure across more than 200 km of grassland in Central Texas. Our analyses indicate that for plant and pollinator communities, both contemporary and historic land management practices have led to significantly dissimilar community composition. Plant and pollinator richness and network nestedness are negatively correlated with phenological period, while pollinator richness is positively correlated with landscape-scale (2 km) urbanized land cover and is higher in historically grazed land, likely due to greater food and nesting resource availability. In contrast, we show that network connectance is positively correlated with phenological period and negatively correlated with landscape-scale urban cover. Finally, we show that pollinator robustness, a measure of resilience to plant species loss, is positively correlated with landscape-scale urbanization, likely due to greater redundancy provided by common weedy plant species. Overall, our results demonstrate that historic grazing regimes, current urbanization levels, and distinct phenological periods can simultaneously drive plant-pollinator community composition and network dynamics in shrinking but critical grassland ecosystems.

WeChat as the coordinator of polymedia: Chinese women maintaining intercultural romantic relationships

This article considers the ways in which the super-sticky all-in-one platform WeChat acts as the coordinator of a polymedia environment – and not just part of the polymedia environment – in mediating intercultural romantic relationships in the Greater Bay Area of China. Based on qualitative interviews, the article explores how WeChat coordinates a diverse range of digital communication tools for typical intercultural couples (Chinese women and foreign men) to mediate and maintain intimacy. The article contends that WeChat mainly derives its coordinator legitimacy and power from the government's prohibition of non-Chinese social media, WeChat's multi-functionality and its ‘local’ nature – Chinese language, social networking capacities and connectivity to other Chinese applications. Finally, this article finds that the power asymmetry caused by WeChat coordinating ecosystem of converged communication has significantly empowered middle-class Chinese women to take control of their intimate intercultural relationships. Research limitations and theoretical implications are discussed.

Nitrogen addition altered the plant-arbuscular mycorrhizal fungi network through reducing redundant interactions in an alpine meadow

Interactions between plants and arbuscular mycorrhizal fungi (AMF) are pivotal in linking belowground soil nutrients with plant-derived carbon in terrestrial ecosystems. However, little is known about the effect of variation in soil nutrients (i.e., nitrogen enrichment) on the structure and phylogenetic characteristics of the mutualistic network. With a 7-year nitrogen addition experiment in an alpine meadow, we built networks for 20 plant species that all occur along the nitrogen addition gradient and their AMF by sequencing 314 root samples. We investigated the responses of association degree (i.e., the number of links of plant or AMF species), network connectance, nestedness, modularity and specialization to different concentrations of nitrogen addition. Phylogenetic signal was calculated to evaluate if the phylogenetically closely related plant species or AMF taxa share similar symbiosis partners. We found that nitrogen addition significantly reduced the plant and AMF association degree, with the generalist (with high association degree) and abundant AMF taxa in nature significantly decreasing association degree and relative abundance (sequencing reads). Therefore, the network connectance and nestedness decreased, but modularity increased with nitrogen addition. Phylogenetic signal of plants (i.e., phylogenetically related plants had similar AMF partners) was always stronger than that of AMF, but the signal vanished with nitrogen addition. The shifted soil properties after nitrogen addition, especially pH, played an important role in regulating the network structures. Our results discover a non-random plant-AMF network shaped by both phylogeny and soil environments in an alpine meadow, and suggest that global nitrogen addition may result in a non-random loss or switch of plant-fungal associations, changes in network structures and phylogenetic relationships, which may have ramification to nutrient exchange and symbiotic performance.

The Effects of Species Abundance, Spatial Distribution, and Phylogeny on a Plant-Ectomycorrhizal Fungal Network.

Plant and root fungal interactions are among the most important belowground ecological interactions, however, the mechanisms underlying pairwise interactions and network patterns of rhizosphere fungi and host plants remain unknown. We tested whether neutral process or spatial constraints individually or jointly best explained quantitative plant–ectomycorrhizal fungal network assembly in a subtropical forest in southern China. Results showed that the observed plant–ectomycorrhizal fungal network had low connectivity, high interaction evenness, and an intermediate level of specialization, with nestedness and modularity both greater than random expectation. Incorporating information on the relative abundance and spatial overlap of plants and fungi well predicted network nestedness and connectance, but not necessarily explained other network metrics such as specificity. Spatial overlap better predicted pairwise species interactions of plants and ectomycorrhizal fungi than species abundance or a combination of species abundance and spatial overlap. There was a significant phylogenetic signal on species degree and interaction strength for ectomycorrhizal fungal but not for plant species. Our study suggests that neutral processes (species abundance matching) and niche/dispersal-related processes (implied by spatial overlap and phylogeny) jointly drive the shaping of a plant-ectomycorrhizal fungal network.

DRLNPS: A deep reinforcement learning network path switching solution

SummaryThis paper proposes a solution to the problem of switching between different network paths. We choose to switch between multiprotocol label switching (MPLS) and software‐defined wide area networking (SD‐WAN) connections specifically as they are the mainstream currently. The solution should maintain a service license agreement (SLA) while choosing SD‐WAN as long as possible to save cost. Therefore, a deep reinforcement learning solution is proposed that predicts when to switch based on bandwidth availability and quality of service (QoS) parameters like jitter and delay. Results show that double deep Q learning in combination with these parameters are suitable to make a sophisticated decision on link switching between MPLS and SD‐WAN.

Gene network profiling in muscle-invasive bladder cancer: A systematic review and meta-analysis.

Determining meta-analysis of transcriptional profiling of muscle-invasive bladder cancer (MIBC) through Gene Expression Omnibus (GEO) datasets has not been investigated. This study aims to define gene expression profiles in MIBC and to identify potential candidate genes and pathways. To review and evaluate gene expression studies in MIBC through publicly available RNA sequencing (RNA-Seq) and microarray data in order to identify potential prognostic and therapeutic targets for MIBC. A systematic literature search of the Ovid MEDLINE, PubMed, and Wiley Cochrane Central Register of Controlled Trials databases was performed using the terms "gene," "gene expression," and "bladder cancer" January 1, 1990 through March 2021 focused on populations with MIBC. In the final analysis, GEO datasets were included. Fixed effect model was employed in the meta-analysis. Gene networking connections and gene-set functional analyses of the identified genes as differentially expressed in MIBC were performed using ImaGEO and GeneMANIA software. A heatmap for the upregulated and downregulated genes was generated along with the correlated pathways. A total of 9 genes were reported in this analysis. Six genes were reported as upregulated (ProTα, SPINT1, UBE2E1, RAB25, KPNB1, HDAC1) and 3 genes as downregulated (NUP188, IPO13, NUP124). Genes were found to be involved in "ubiquitin mediated proteolysis," "protein processing in endoplasmic reticulum," "transcriptional misregulation in cancer," and "RNA transport" pathways.

Metacommunity robustness to invasion in mutualistic and antagonistic networks

One of the most significant threats to biodiversity is alien species invasion, and consequently understanding and predicting biological invasions has become an important issue in ecology. While numerous studies have explored the effect of community diversity and structure on invasion success, a systematic comparative analysis on system robustness to invasion between antagonistic and mutualistic networks from a metacommunity perspective is still lacking. Here we seek to address this gap using patch-dynamic models, which integrate local communities into the landscape metacommunity. We find that both mutualistic and antagonistic metacommunities displayed qualitatively similar responses to species invasion, except for animal invasion in antagonistic networks. Specifically, increasing network size and connectance generally promoted metacommunity persistence, while nestedness (negative) and modularity (positive) had contrasting effects on metacommunity robustness to invasion. However, these structural effects were strongly dependent on the generalization levels of both invader and the resident species it displaces. Overall, this study provides new and more general insights into how alien species are well integrated into native networks and how they affect metacommunity persistence.

Min-Time Coverage in Constricted Environments: Problem Formulations and Complexity Analysis

This work deals with the task allocation and robot routing problems that arise in a class of networked mobile robot systems. The defining characteristics of these systems are: 1) the constricting nature of their operational environment and 2) the need to coordinate the robot motion in order to maintain full connectivity of a multihop wireless communication network connecting the robots with each other and a master controller that supervises the entire operation. These two elements give rise to resource allocation structures and traffic dynamics that transcend the state of the art of the corresponding theory and challenge our current understandings and insights for these dynamics and their effective management. We provide: 1) a systematic introduction of the considered problems and of the elements that differentiate them from similar task allocation and traffic scheduling problems already studied in the literature; 2) complete analytical characterizations of these problems in the form of mathematical programming formulations; and 3) a formal analysis of the worst-case computational complexity of these problems and of certain factors that determine this complexity. Furthermore, the presented results define a base for the development of solution approaches to the considered problems able to effectively and systematically manage the identified tradeoff between the operational efficiency of the derived solutions and their computational cost.

Interaction capacity as a potential driver of community diversity.

How patterns in community diversity emerge is a long-standing question in ecology. Studies suggested that community diversity and interspecific interactions are interdependent. However, evidence from high-diversity ecological communities is lacking because of practical challenges in characterizing speciose communities and their interactions. Here, I analysed time-varying interaction networks that were reconstructed using 1197 species, DNA-based ecological time series taken from experimental rice plots and empirical dynamic modelling, and introduced ‘interaction capacity', namely, the sum of interaction strength that a single species gives and receives, as a potential driver of community diversity. As community diversity increases, the number of interactions increases exponentially but the mean interaction capacity of a community becomes saturated, weakening interspecific interactions. These patterns are modelled with simple mathematical equations, based on which I propose the ‘interaction capacity hypothesis': that interaction capacity and network connectance can be two fundamental properties that influence community diversity. Furthermore, I show that total DNA abundance and temperature influence interaction capacity and connectance nonlinearly, explaining a large proportion of diversity patterns observed in various systems. The interaction capacity hypothesis enables mechanistic explanations of community diversity. Therefore, analysing ecological community data from the viewpoint of interaction capacity would provide new insight into community diversity.

EEG-based functional connectivity and executive control in patients with Parkinson’s disease and freezing of gait

ObjectiveTo explore changes over time in the network specificities underpinning a visual attentional task in patients with Parkinson’s disease and freezing of gait (the PD + FoG group), patients with Parkinson’s disease but no FoG (PD-FoG), and healthy controls (HCs). MethodsHigh-resolution electroencephalography (EEG) data were acquired for 15 PD + FoG patients, 14 PD-FoG patients, and 18 HCs performing the Attention Network Test. After source localization, functional connectivity was assessed and compared by applying the dynamic phase-locking value method. ResultsThe PD + FoG patients showed an impairment in executive control. Furthermore, the PD + FoG patients showed abnormally high theta band connectivity (relative to HCs, and 400 to 600 ms after target presentation) in a network connecting the orbitofrontal and occipitotemporal regions. ConclusionsIn PD + FoG, the greater functional connectivity between the visual network and the regions to which executive function has been attributed might indicate greater reliance on environmental features when seeking to overcome the impairment in executive control. SignificanceFoG in PD involves cognitive, attentional and executive dysfunctions. Our observation of abnormally high connectivity in PD + FoG patients argues in favor of the interference model of FoG.

Innovative Multi-Actor Collaborations as Collective Actors and Institutionalized Spaces. The Case of Food Governance Transformation in Leuven (Belgium)

The sustainable transformation of food systems is a particularly prolific field in which innovative multi-actor collaborations (IMACs) are being tested. Despite the growing literature on food governance and transformation of food systems, and on the principles of alternative food networks and local food strategies, little is known about how these are implemented and how multi-actor networks are coordinated and governed. Taking food as a lens, our objectives are to identify (1) how IMACs are established, (2) how collaboration is enacted within them, and (3) how governance innovations in these fields affect and are affected by broader urban governance innovation. Methodologically, we take a transdisciplinary action research approach, combining different groups of researchers with stakeholders involved in two on-going and interacting IMAC trajectories in Leuven (Belgium), i.e., the non-profit governmental organization Leuven2030 aiming to achieve climate-neutrality and the parallel collective development and implementation of the local food strategy “Food Connects.” After reconstructing the trajectory of these IMACs from a governance perspective and discussing their current limitations, we realize that these IMACs perform both as collective actors and as institutionalized spaces for experimentation and transformative change. Our findings demonstrate that IMACs can be an empowering tool for local actors to challenge supra-local and systemic power imbalance and injustice; that networking and supra-local connections of urban actors can increase the legitimacy and outreach of transition processes, mobilization of resources and peer-learning; and that the consolidation of IMACs builds on previous sedimentations of experimentation and benefits from the impulse of political will in specific windows of opportunity. We conclude that the institutionalization of common objectives set within IMACs requires a parallel institutionalization of governance structures that enabled reaching them, which entails defining specific roles and responsibilities among actors and ensuring stable spaces for conflict, deliberation, and negotiation.

Review on Deep Learning based Network Security Tools in Detecting Real-Time Vulnerabilities

Network connected hardware and software systems are always open to vulnerabilities when they are connected with an outdated firewall or an unknown Wi-Fi access. Therefore network based anti-virus software and intrusion detection systems are widely installed in every network connected hardwares. However, the pre-installed security softwares are not quite capable in identifying the attacks when evolved. Similarly, the traditional network security tools that are available in the current market are not efficient in handling the attacks when the system is connected with a cloud environment or IoT network. Hence, recent algorithms of security tools are incorporated with the deep learning network for improving its intrusion detection rate. The adaptability of deep learning network is comparatively high over the traditional software tools when it is employed with a feedback network. The feedback connections included in the deep learning networks produce a response signal to their own network connections as a training signal for improving their work performances. This improves the performances of deep learning-based security tools while it is in real-time operation. The motive of the work is to review and present the attainments of the deep learning-based vulnerability detection models along with their limitations.

Longitudinal Changes of Resting-State Networks in Children With Attention-Deficit/Hyperactivity Disorder and Typically Developing Children

BackgroundAttention-deficit/hyperactivity disorder (ADHD) is a prevalent childhood neurodevelopmental disorder. Given the profound brain changes that occur across childhood and adolescence, it is important to identify functional networks that exhibit differential developmental patterns in children with ADHD. This study sought to examine whether children with ADHD exhibit differential developmental trajectories in functional connectivity compared with typically developing children using a network-based approach. MethodsThis longitudinal neuroimaging study included 175 participants (91 children with ADHD and 84 control children without ADHD) between ages 9 and 14 and up to 3 waves (173 total resting-state scans in children with ADHD and 197 scans in control children). We adopted network-based statistics to identify connected components with trajectories of development that differed between groups. ResultsChildren with ADHD exhibited differential developmental trajectories compared with typically developing control children in networks connecting cortical and limbic regions as well as between visual and higher-order cognitive regions. A pattern of reduction in functional connectivity between corticolimbic networks was seen across development in the control group that was not present in the ADHD group. Conversely, the ADHD group showed a significant decrease in connectivity between predominantly visual and higher-order cognitive networks that was not displayed in the control group. ConclusionsOur findings show that the developmental trajectories in children with ADHD are characterized by a subnetwork involving different trajectories predominantly between corticolimbic regions and between visual and higher-order cognitive network connections. These findings highlight the importance of examining the longitudinal maturational course to understand the development of functional connectivity networks in children with ADHD.

Molecular dynamics studies of entropic elasticity of condensed lattice networks connected with uniform functionality f = 4.

To study the linear region of entropic elasticity, we considered the simplest physical model possible and extracted the linear entropic regime by using the least squares fit and the minimum of the mean absolute error. With regard to the effect of the fluctuation of the strand length Ns, the strand length with fluctuation was set to a form proportional to (1.0 + C (R - 0.5)), where R is a uniform random number between 0 and 1 and C is the amplitude of fluctuation. This form enabled us to analytically calculate the fluctuation dependence of the elastic modulus G. To reveal the linear regions of entropic elasticity as a function of the strand length between neighboring nodes in lattices, molecular dynamics (MD) simulations of condensed lattice networks with harmonic bonds without the excluded volume interactions were performed. Stress-strain curves were estimated by performing uniaxial stretching MD simulations under periodic boundary conditions with a bead number density of 0.85. First, we used a diamond lattice with functionality f = 4. The linear region of the entropic elasticity was found to become larger with the increasing number of beads in a strand Ns. For Ns = 100, the linear region had a strain of up to 8 for a regular diamond lattice. We investigated the effect of strand length fluctuation on the diamond lattice, and we confirmed that the equilibrium shear modulus G increases as the obtained analytical prediction and the linear entropic region in the stress-strain curves becomes narrower with increasing fluctuation of Ns. To investigate the difference in network topology with the same functionality f and uniform strand length Ns, we performed MD simulations on regular networks of the BC-8 structure with f = 4 prepared from the ab initio DFT calculations of carbon at high pressure. We found that the elastic behavior depends on the network connectivity (i.e., topology). This indicates that the network topology plays an important role in the emergence of nonlinearity owing to the crossover from entropic to energetic elasticity.

Internet addiction and criminal phenomenology: an insight on the Social Networking Sites addiction and the online death games

With the advent of the virtual world as the counterpart of our daily lives, several concerns emerged. The following paper will focus on the iGeneration, a fragile social group grown up between the online and the offline world, and its chances to develop a technology addiction. Secondly, an insight on the illustrative and extreme scenario of the Blue Whale Challenge, a death challenge emerged on social networking sites, its implications and connection with the real world.

Female leadership in the Arab world: an ethnographic study of educational leaders

ABSTRACT The Arab world is very diverse when it comes to leadership practices. The females’ level of participation in leadership positions in Arab countries ranges from very restricted to fully engaged. Taking on leadership roles imposes many challenges both on micro and macro levels. The aim of this study is to explore the leadership practices of Arab female educational leaders and understand the impact that environment and culture have on their leadership practices. Using an ethnographic approach, seven female educational leaders, who lived and worked in leadership positions in eight Arab countries, revealed that they practice a combination of transformational, servant and instructional leadership dimensions. However, a new leadership style emerged ensuring that these leaders and their followers are valued for who they are and rewarded for what they do. This study highlights the combination of both aspects of change and leadership as critical to female educational leaders success in addition to mentoring, informal networking and social connections. Furthermore, having partner and family support were identified as a cornerstone to their career advancement. This study suggests the need to design policies that support teachers to become involved in decision making and to promote them into leadership positions.

Trophic rewilding benefits a tropical community through direct and indirect network effects

Species reintroductions can be used as a conservation strategy to restore ecological interactions and the functionality of impoverished ecosystems. The ecological effects of reintroductions go beyond restoring pairwise interactions, because reintroductions can change how extant species are indirectly linked to each other in an ecological community. These indirect pathways, in turn, may shape a myriad of ecological and evolutionary processes operating in ecological systems. Here, we investigated how reintroductions may affect the direct and indirect pathways connecting species in ecological networks. We modeled the potential effects of the reintroduction of four frugivore species (channel‐billed toucans, red‐humped agoutis, brown howler monkeys and yellow‐footed tortoises) to the local seed dispersal network in an Atlantic Forest site, the Tijuca National Park (Rio de Janeiro, Brazil). We used a seed dispersal interaction dataset together with data on species occurrences in Tijuca to build network models. Then, we calculated how network structure and the total amount of indirect effects varied across simulated networks with and without the reintroduced species. Using random reintroduction simulations, we tested if the observed network changes were expected merely from the increase in species richness. The reintroduction of the frugivore species increased network connectance, nestedness, robustness, number of pathways and total amount of indirect effects in all simulated networks. The increase in number of pathways with the addition of the four reintroduced species was greater than the sum of isolated effects for each species, because some interaction pathways contained several reintroduced species. These changes in network metrics were significantly greater than if a randomly chosen set of four species was reintroduced. Furthermore, our results indicate that multiple reintroductions in the same area, known as refaunation, may have an even greater restoration effect than single species reintroductions through increased indirect connections in the network.