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Network theory

Sanna Rönkä, Anu Katainen
BACKGROUND: The non-medical use of prescription drugs is a growing phenomenon associated with increasing health-related harms. However, little is known about the drivers of this process among illicit drug users. Our aim is to show how the qualities of pharmaceutical drugs, pharmaceutical related knowledge, online communities sharing this knowledge and medical professionals mediate and transform the consumption behaviour related to pharmaceutical drugs. METHODS: The data consist of discussion threads from an online drug use forum...
October 18, 2016: International Journal on Drug Policy
Guangquan Lu, Ying Xiong, Chuan Ding, Yunpeng Wang
The schedule of urban road network recovery caused by rainstorms, snow, and other bad weather conditions, traffic incidents, and other daily events is essential. However, limited studies have been conducted to investigate this problem. We fill this research gap by proposing an optimal schedule for urban road network repair with limited repair resources based on the greedy algorithm. Critical links will be given priority in repair according to the basic concept of the greedy algorithm. In this study, the link whose restoration produces the ratio of the system-wide travel time of the current network to the worst network is the minimum...
2016: PloS One
Luca Santini, Santiago Saura, Carlo Rondinini
One of the biggest challenges in large-scale conservation is quantifying connectivity at broad geographic scales and for a large set of species. Because connectivity analyses can be computationally intensive, and the planning process quite complex when multiple taxa are involved, assessing connectivity at large spatial extents for many species turns to be often intractable. Such limitation results in that conducted assessments are often partial by focusing on a few key species only, or are generic by considering a range of dispersal distances and a fixed set of areas to connect that are not directly linked to the actual spatial distribution or mobility of particular species...
2016: PloS One
Ruben Perez-Carrasco, Pilar Guerrero, James Briscoe, Karen M Page
During tissue development, patterns of gene expression determine the spatial arrangement of cell types. In many cases, gradients of secreted signalling molecules-morphogens-guide this process by controlling downstream transcriptional networks. A mechanism commonly used in these networks to convert the continuous information provided by the gradient into discrete transitions between adjacent cell types is the genetic toggle switch, composed of cross-repressing transcriptional determinants. Previous analyses have emphasised the steady state output of these mechanisms...
October 2016: PLoS Computational Biology
Giuseppe Lanza, Maria A Chiacchio
Exploration of interfacial hydration networks of zwitterion and non-ionized trialanine has been performed using DFT-M062X quantum chemical computations explicitly considering up to 41 water molecules. The step-by-step water molecules peptide surrounding, carried out for unfolded extended (β), polyproline II (PPII) conformations reveals the crucial importance of explicit solvent effects in stabilizing the zwitterion form and the left-handed PPII-helix ubiquitously found at room temperature for short polyalanines...
October 21, 2016: Journal of Physical Chemistry. B
Erfan Dashtimoghadam, Ghasem Bahlakeh, Hamed Salimi-Kenari, Mohammad Mahdi Hasani-Sadrabadi, Hamid Mirzadeh, Bo Nyström
The temperature-induced gelation of chitosan/glycerophosphate (Chs/GP) systems through physical interactions has shown great potential for various biomedical applications. In the present work, hydroxyethyl cellulose (HEC) was added to the thermosensitive Chs/GP solution to improve the mechanical strength and gel properties of the incipient Chs/HEC/GP gel in comparison with the Chs/GP hydrogel at body temperature. The physical features of the macromolecular complexes formed by the synergistic interaction between chitosan and hydroxyethyl cellulose in the presence of β-glycerophosphate disodium salt solution have been studied essentially from a rheological point of view...
October 21, 2016: Biomacromolecules
Eric Smart, Adeeta Aulakh, Carolyn McDougall, Patty Rigby, Gillian King
PURPOSE: Identify strategies youth perceive will optimize their engagement in goal pursuit in life skills and transition programs using an engagement framework involving affective, cognitive, and behavioral components. METHODS: A qualitative descriptive design was used. Two semi-structured interviews were conducted with seven youth. The first was informed by a prior observation session, and the second occurred after the program ended and explored youths' perceptions of whether and how their engagement changed...
October 21, 2016: Disability and Rehabilitation
Chinglin Wu, Suyu Zhong, Hsuehchih Chen
Remote association is a core ability that influences creative output. In contrast to close association, remote association is commonly agreed to be connected with more original and unique concepts. However, although existing studies have discovered that creativity is closely related to the white-matter structure of the brain, there are no studies that examine the relevance between the connectivity efficiencies and creativity of the brain regions from the perspective of networks. Consequently, this study constructed a brain white matter network structure that consisted of cerebral tissues and nerve fibers and used graph theory to analyze the connection efficiencies among the network nodes, further illuminating the differences between remote and close association in relation to the connectivity of the brain network...
2016: PloS One
Ana María Hernández-Hernández, Dolores Viga-de Alva, Rodrigo Huerta-Quintanilla, Efrain Canto-Lugo, Hugo Laviada-Molina, Fernanda Molina-Segui
We use complex network theory to study the differences between the friendship concepts in elementary school and university students. Four friendship networks were identified from surveys. Three of these networks are from elementary schools; two are located in the rural area of Yucatán and the other is in the urban area of Mérida, Yucatán. We analyzed the structure and the communities of these friendship networks and found significant differences among those at the elementary schools compared with those at the university...
2016: PloS One
Kelsie Y Chesnut, Melissa Barragan, Jason Gravel, Natalie A Pifer, Keramet Reiter, Nicole Sherman, George E Tita
OBJECTIVES: California has strict firearm-related laws and is exceptional in its regulation of firearms retailers. Though evidence suggests that these laws can reduce illegal access to guns, high levels of gun violence persist in Los Angeles (LA), California. This research seeks to describe the sources of guns accessed by active offenders in LA, California and reports offenders' motivations for obtaining guns. SETTING: Los Angeles County Jail (LACJ) system (four facilities)...
October 6, 2016: Injury Prevention: Journal of the International Society for Child and Adolescent Injury Prevention
Annerine Roos, Jean-Paul Fouche, Dan J Stein
Evidence suggests that women who suffer from intimate partner violence (IPV) and posttraumatic stress disorder (PTSD) have structural and functional alterations in specific brain regions. Yet, little is known about how brain connectivity may be altered in individuals with IPV, but without PTSD. Women exposed to IPV (n = 18) and healthy controls (n = 18) underwent structural brain imaging using a Siemens 3T MRI. Global and regional brain network connectivity measures were determined, using graph theory analyses...
October 18, 2016: Brain Imaging and Behavior
Dwayne Van Eerd, Kristine Newman, Ryan DeForge, Robin Urquhart, Evelyn Cornelissen, Katie N Dainty
BACKGROUND: Developing a healthcare delivery system that is more responsive to the future challenges of an aging population is a priority in Canada. The World Health Organization acknowledges the need for knowledge translation frameworks in aging and health. Knowledge brokering (KB) is a specific knowledge translation approach that includes making connections between people to facilitate the use of evidence. Knowledge gaps exist about KB roles, approaches, and guiding frameworks. The objective of the scoping review is to identify and describe KB approaches and the underlying conceptual frameworks (models, theories) used to guide the approaches that could support healthy aging...
October 19, 2016: Implementation Science: IS
Lin Li, Mary Cazzell, Olajide Babawale, Hanli Liu
Atlas-guided diffuse optical tomography (atlas-DOT) is a computational means to image changes in cortical hemodynamic signals during human brain activities. Graph theory analysis (GTA) is a network analysis tool commonly used in functional neuroimaging to study brain networks. Atlas-DOT has not been analyzed with GTA to derive large-scale brain connectivity/networks based on near-infrared spectroscopy (NIRS) measurements. We introduced an automated voxel classification (AVC) method that facilitated the use of GTA with atlas-DOT images by grouping unequal-sized finite element voxels into anatomically meaningful regions of interest within the human brain...
October 2016: Neurophotonics
Jérémie Barral, Alex D Reyes
The balance between excitation and inhibition (E-I balance) is maintained across brain regions though the network size, strength and number of synaptic connections, and connection architecture may vary substantially. We use a culture preparation to examine the homeostatic synaptic scaling rules that produce E-I balance and in vivo-like activity. We show that synaptic strength scales with the number of connections K as ∼ , close to the ideal theoretical value. Using optogenetic techniques, we delivered spatiotemporally patterned stimuli to neurons and confirmed key theoretical predictions: E-I balance is maintained, active decorrelation occurs and the spiking correlation increases with firing rate...
October 17, 2016: Nature Neuroscience
Paul S Foster, Tyler Hubbard, Ransom W Campbell, Jonathan Poole, Michael Pridmore, Chris Bell, David W Harrison
The theory of spreading activation proposes that the activation of a semantic memory node may spread along bidirectional associative links to other related nodes. Although this theory was originally proposed to explain semantic memory networks, a similar process may be said to exist with episodic or emotional memory networks. The Somatic Marker hypothesis proposes that remembering an emotional memory activates the somatic sensations associated with the memory. An integration of these two models suggests that as spreading activation in emotional memory networks increases, a greater number of associated somatic markers would become activated...
July 15, 2016: Brain Informatics
Yanling Zhou, Xianrong Liu, Qijun Wang, Lisheng Wang, Baoling Song
The reaction of CoCl2·6H2O, N,N-bis-(2-hy-droxy-eth-yl)glycine and tri-ethyl-amine (Et3N) in ethanol solution under solvothermal conditions produced crystals of [N,N-bis-(2-hy-droxy-eth-yl)glycinato]chloridocobalt(II), [Co(C6H12NO4)Cl]. The Co(II) ion is coordinated in a slightly distorted trigonal-bipyramidal environment which is defined by three O atoms occupying the equatorial plane and the N and Cl atoms in the apical sites. In the crystal, two types of O-H⋯O hydrogen bonds connect the mol-ecules, forming a two-dimensional network parallel to (001)...
October 1, 2016: Acta Crystallographica. Section E, Crystallographic Communications
Wenqing Fu, Sharon R Browning, Brian L Browning, Joshua M Akey
Identifying and characterizing genomic regions that are shared identical by descent (IBD) among individuals can yield insight into population history, facilitate the identification of adaptively evolving loci, and be an important tool in disease gene mapping. Although increasingly large collections of exome sequences have been generated, it is challenging to detect IBD segments in exomes, precluding many potentially informative downstream analyses. Here, we describe an approach, ExIBD, to robustly detect IBD segments in exome-sequencing data, rigorously evaluate its performance, and apply this method to high-coverage exomes from 6,515 European and African Americans...
October 6, 2016: American Journal of Human Genetics
Nele A J De Witte, Sven C Mueller
Anxiety and depression are associated with altered communication within global brain networks and between these networks and the amygdala. Functional connectivity studies demonstrate an effect of anxiety and depression on four critical brain networks involved in top-down attentional control (fronto-parietal network; FPN), salience detection and error monitoring (cingulo-opercular network; CON), bottom-up stimulus-driven attention (ventral attention network; VAN), and default mode (default mode network; DMN)...
October 15, 2016: Brain Imaging and Behavior
Michelle N Servaas, Linda Geerligs, Jojanneke A Bastiaansen, Remco J Renken, Jan-Bernard C Marsman, Ilja M Nolte, Johan Ormel, André Aleman, Harriëtte Riese
Neuroticism and genetic variation in the serotonin-transporter (SLC6A4) and catechol-O-methyltransferase (COMT) gene are risk factors for psychopathology. Alterations in the functional integration and segregation of neural circuits have recently been found in individuals scoring higher on neuroticism. The aim of the current study was to investigate how genetic risk factors impact functional network organization and whether genetic risk factors moderate the association between neuroticism and functional network organization...
October 14, 2016: Brain Imaging and Behavior
Douglas McLelland, Rufin VanRullen
Several theories have been advanced to explain how cross-frequency coupling, the interaction of neuronal oscillations at different frequencies, could enable item multiplexing in neural systems. The communication-through-coherence theory proposes that phase-matching of gamma oscillations between areas enables selective processing of a single item at a time, and a later refinement of the theory includes a theta-frequency oscillation that provides a periodic reset of the system. Alternatively, the theta-gamma neural code theory proposes that a sequence of items is processed, one per gamma cycle, and that this sequence is repeated or updated across theta cycles...
October 2016: PLoS Computational Biology
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