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Graph Theory

Kyoko Ohashi, Carl M Anderson, Elizabeth A Bolger, Alaptagin Khan, Cynthia E McGreenery, Martin H Teicher
Childhood maltreatment is a major risk factor for psychopathology. It is also associated with alterations in the network architecture of the brain, which we hypothesized may play a significant role in the development of psychopathology. In this study, we analyzed the global network architecture of physically healthy unmedicated 18-25 year old subjects (n=262) using diffusion tensor imaging (DTI) MRI and tractography. Anatomical networks were constructed from fiber streams interconnecting 90 cortical or subcortical regions for subjects with no-to-low (n=122) versus moderate-to-high (n=140) exposure to maltreatment...
February 14, 2017: NeuroImage
Uttam Bhat, Munik Shrestha, Laurent Hébert-Dufresne
The giant k-core-maximal connected subgraph of a network where each node has at least k neighbors-is important in the study of phase transitions and in applications of network theory. Unlike Erdős-Rényi graphs and other random networks where k-cores emerge discontinuously for k≥3, we show that transitive linking (or triadic closure) leads to 3-cores emerging through single or double phase transitions of both discontinuous and continuous nature. We also develop a k-core calculation that includes clustering and provides insights into how high-level connectivity emerges...
January 2017: Physical Review. E
João Ribeiro, Pedro Silva, Ricardo Duarte, Keith Davids, Júlio Garganta
This paper discusses how social network analyses and graph theory can be implemented in team sports performance analyses to evaluate individual (micro) and collective (macro) performance data, and how to use this information for designing practice tasks. Moreover, we briefly outline possible limitations of social network studies and provide suggestions for future research. Instead of cataloguing discrete events or player actions, it has been argued that researchers need to consider the synergistic interpersonal processes emerging between teammates in competitive performance environments...
February 15, 2017: Sports Medicine
Lucas de F Carvalho, Giselle Pianowski, Nelson H Filho
The Clinical Dimensional Personality Inventory (IDCP) is a 163-item self-report tool developed for the assessment of 12 dimensions of personality pathology. One of the scales comprising the instrument-the Dependency scale-is intended to provide psychometric information on traits closely related to the Dependent Personality Disorder (DPD). In the present study, we used both Item Response Theory modeling and Receiver Operating Characteristic curve analysis to establishing a clinically meaningful cutoff for the IDCP Dependency Scale...
February 3, 2017: Psychiatry Research
Huanan Li, Suwun Suwunnarat, Ragnar Fleischmann, Holger Schanz, Tsampikos Kottos
We employ random matrix theory in order to investigate coherent perfect absorption (CPA) in lossy systems with complex internal dynamics. The loss strength γ_{CPA} and energy E_{CPA}, for which a CPA occurs, are expressed in terms of the eigenmodes of the isolated cavity-thus carrying over the information about the chaotic nature of the target-and their coupling to a finite number of scattering channels. Our results are tested against numerical calculations using complex networks of resonators and chaotic graphs as CPA cavities...
January 27, 2017: Physical Review Letters
Nantia D Iakovidou
The brain is one of the largest and most complex organs in the human body and electroencephalography (EEG) is a non-invasive electrophysiological monitoring method that is used to record the electrical activity of the brain. Lately, the functional connectivity in human brain has been regarded and studied as a complex network using electroencephalographic (EEG) signals. This means that the brain is studied as a connected system where nodes, or units, represent different specialized brain regions and links, or connections, represent communication pathways between the nodes...
February 8, 2017: Brain Connectivity
Taolin Chen, Keith M Kendrick, Jinhui Wang, Min Wu, Kaiming Li, Xiaoqi Huang, Yuejia Luo, Su Lui, John A Sweeney, Qiyong Gong
Major depressive disorder (MDD) has been associated with disruptions in the topological organization of brain morphological networks in group-level data. Such disruptions have not yet been identified in single-patients, which is needed to show relations with symptom severity and to evaluate their potential as biomarkers for illness. To address this issue, we conducted a cross-sectional structural brain network study of 33 treatment-naive, first-episode MDD patients and 33 age-, gender-, and education-matched healthy controls (HCs)...
February 8, 2017: Human Brain Mapping
Dong Zhang, Jie Liang
The graph-based block transform recently emerged as an effective tool for compressing some special signals such as depth images in 3D videos. However, in existing methods, overheads are required to describe the graph of the block, from which the decoder has to calculate the transform via timeconsuming eigen-decomposition. To address these problems, in this paper we aim to develop a single graph-based transform for a class of 2-D piecewise smooth signals with similar discontinuity patterns. We first consider the deterministic case with a known discontinuity location in each row...
January 31, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Aparna Rai, Priodyuti Pradhan, Jyothi Nagraj, K Lohitesh, Rajdeep Chowdhury, Sarika Jalan
Cancer complexome comprises a heterogeneous and multifactorial milieu that varies in cytology, physiology, signaling mechanisms and response to therapy. The combined framework of network theory and spectral graph theory along with the multilayer analysis provides a comprehensive approach to analyze the proteomic data of seven different cancers, namely, breast, oral, ovarian, cervical, lung, colon and prostate. Our analysis demonstrates that the protein-protein interaction networks of the normal and the cancerous tissues associated with the seven cancers have overall similar structural and spectral properties...
February 3, 2017: Scientific Reports
Yingnan Cong, Yao-Ban Chan, Charles A Phillips, Michael A Langston, Mark A Ragan
Bacteria and archaea can exchange genetic material across lineages through processes of lateral genetic transfer (LGT). Collectively, these exchange relationships can be modeled as a network and analyzed using concepts from graph theory. In particular, densely connected regions within an LGT network have been defined as genetic exchange communities (GECs). However, it has been problematic to construct networks in which edges solely represent LGT. Here we apply term frequency-inverse document frequency (TF-IDF), an alignment-free method originating from document analysis, to infer regions of lateral origin in bacterial genomes...
2017: Frontiers in Microbiology
Adam Sage, Courtney Roberts, Lorie Geryk, Betsy Sleath, Deborah Tate, Delesha Carpenter
BACKGROUND: Self-regulation theory suggests people learn to influence their own behavior through self-monitoring, goal-setting, feedback, self-reward, and self-instruction, all of which smartphones are now capable of facilitating. Several mobile apps exist to manage asthma; however, little evidence exists about whether these apps employ user-centered design processes that adhere to government usability guidelines for mobile apps. OBJECTIVE: Building upon a previous study that documented adolescent preferences for an asthma self-management app, we employed a user-centered approach to assess the usability of a high-fidelity wireframe for an asthma self-management app intended for use by adolescents with persistent asthma...
February 1, 2017: JMIR Human Factors
Yuanshi Zheng, Jingying Ma, Long Wang
In this brief, we consider the consensus problem of hybrid multiagent systems. First, the hybrid multiagent system is proposed, which is composed of continuous-time and discrete-time dynamic agents. Then, three kinds of consensus protocols are presented for the hybrid multiagent system. The analysis tool developed in this brief is based on the matrix theory and graph theory. With different restrictions of the sampling period, some necessary and sufficient conditions are established for solving the consensus of the hybrid multiagent system...
January 27, 2017: IEEE Transactions on Neural Networks and Learning Systems
John A E Anderson, Saman Sarraf, Tarek Amer, Buddhika Bellana, Vincent Man, Karen L Campbell, Lynn Hasher, Cheryl L Grady
Testing older adults in the morning generally improves behavioral performance relative to afternoon testing. Morning testing is also associated with brain activity similar to that of young adults. Here, we used graph theory to explore how time of day (TOD) affects the organization of brain networks in older adults across rest and task states. We used nodes from the automated anatomical labeling atlas to construct participant-specific correlation matrices of fMRI data obtained during 1-back tasks with interference and rest...
October 19, 2016: Journal of Cognitive Neuroscience
Quanquan Gu, Hengyi Cao, Min Xuan, Wei Luo, Xiaojun Guan, Jingjing Xu, Peiyu Huang, Minming Zhang, Xiaojun Xu
INTRODUCTION: Evidence has indicated a strong association between hyperactivity in the cerebello-thalamo-motor cortical loop and resting tremor in Parkinson's disease (PD). Within this loop, the thalamus serves as a central hub based on its structural centrality in the generation of resting tremor. To study whether this thalamic abnormality leads to an alteration at the whole-brain level, our study investigated the role of the thalamus in patients with parkinsonian resting tremor in a large-scale brain network context...
January 2017: Brain and Behavior
Eva Výtvarová, Radek Mareček, Jan Fousek, Ondřej Strýček, Ivan Rektor
OBJECTIVES: The aim was to describe the contribution of basal ganglia (BG) thalamo-cortical circuitry to the whole-brain functional connectivity in focal epilepsies. METHODS: Interictal resting-state fMRI recordings were acquired in 46 persons with focal epilepsies. Of these 46, 22 had temporal lobe epilepsy: 9 left temporal (LTLE), 13 right temporal (RTLE); 15 had frontal lobe epilepsy (FLE); and 9 had parietal/occipital lobe epilepsy (POLE). There were 20 healthy controls...
2017: NeuroImage: Clinical
Gareth A Tribello, Federico Giberti, Gabriele Cesare Sosso, Matteo Salvalaglio, Michele Parrinello
In this paper a new method for identifying the phases contained in a system composed of atoms/molecules is introduced. The method is rooted in graph theory and combines atom centered symmetry functions, adjacency matrices and clustering algorithms to identify regions of space where the properties of the system constituents can be considered uniform. We show how this method can be used to define collective variables and how these collective variables can be used to enhance the sampling of nucleation events. We then show how this method can be used to analyze simulations of crystal nucleation and growth by using it to analyze simulations of the nucleation of the molecular crystal urea and simulations of nucleation in a semiconducting alloy...
January 25, 2017: Journal of Chemical Theory and Computation
Sule Tinaz, Peter M Lauro, Pritha Ghosh, Codrin Lungu, Silvina G Horovitz
Parkinson's disease (PD) leads to dysfunction in multiple cortico-striatal circuits. The neurodegeneration has also been associated with impaired white matter integrity. This structural and functional "disconnection" in PD needs further characterization. We investigated the structural and functional organization of the PD whole brain connectome consisting of 200 nodes using diffusion tensor imaging and resting-state functional MRI, respectively. Data from 20 non-demented PD patients on dopaminergic medication and 20 matched controls were analyzed using graph theory-based methods...
2017: NeuroImage: Clinical
Chunlin Zhao, Min Zhao, Yong Yang, Junfeng Gao, Nini Rao, Pan Lin
The organization of the brain functional network is associated with mental fatigue, but little is known about the brain network topology that is modulated by the mental fatigue. In this study, we used the graph theory approach to investigate reconfiguration changes in functional networks of different electroencephalography (EEG) bands from 16 subjects performing a simulated driving task. Behavior and brain functional networks were compared between the normal and driving mental fatigue states. The scores of subjective self-reports indicated that 90 mins of simulated driving induced mental fatigue...
March 18, 2016: IEEE Journal of Biomedical and Health Informatics
Xiao-Jian Li, Guang-Hong Yang
This paper is concerned with the adaptive decentralized fault-tolerant tracking control problem for a class of uncertain interconnected nonlinear systems with unknown strong interconnections. An algebraic graph theory result is introduced to address the considered interconnections. In addition, to achieve the desirable tracking performance, a neural-network-based robust adaptive decentralized fault-tolerant control (FTC) scheme is given to compensate the actuator faults and system uncertainties. Furthermore, via the Lyapunov analysis method, it is proven that all the signals of the resulting closed-loop system are semiglobally bounded, and the tracking errors of each subsystem exponentially converge to a compact set, whose radius is adjustable by choosing different controller design parameters...
October 26, 2016: IEEE Transactions on Neural Networks and Learning Systems
Sugeerth Murugesan, Kristofer Bouchard, Jesse A Brown, Bernd Hamann, William W Seeley, Andrew Trujillo, Gunther H Weber
We present Brain Modulyzer, an interactive visual exploration tool for functional magnetic resonance imaging (fMRI) brain scans, aimed at analyzing the correlation between different brain regions when resting or when performing mental tasks. Brain Modulyzer combines multiple coordinated views-such as heat maps, node link diagrams and anatomical views-using brushing and linking to provide an anatomical context for brain connectivity data. Integrating methods from graph theory and analysis, e.g., community detection and derived graph measures, makes it possible to explore the modular and hierarchical organization of functional brain networks...
May 9, 2016: IEEE/ACM Transactions on Computational Biology and Bioinformatics
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