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Sample records for brains small worlds

  1. Small-World Propensity and Weighted Brain Networks.

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    Muldoon, Sarah Feldt; Bridgeford, Eric W; Bassett, Danielle S

    2016-02-25

    Quantitative descriptions of network structure can provide fundamental insights into the function of interconnected complex systems. Small-world structure, diagnosed by high local clustering yet short average path length between any two nodes, promotes information flow in coupled systems, a key function that can differ across conditions or between groups. However, current techniques to quantify small-worldness are density dependent and neglect important features such as the strength of network connections, limiting their application in real-world systems. Here, we address both limitations with a novel metric called the Small-World Propensity (SWP). In its binary instantiation, the SWP provides an unbiased assessment of small-world structure in networks of varying densities. We extend this concept to the case of weighted brain networks by developing (i) a standardized procedure for generating weighted small-world networks, (ii) a weighted extension of the SWP, and (iii) a method for mapping observed brain network data onto the theoretical model. In applying these techniques to compare real-world brain networks, we uncover the surprising fact that the canonical biological small-world network, the C. elegans neuronal network, has strikingly low SWP. These metrics, models, and maps form a coherent toolbox for the assessment and comparison of architectural properties in brain networks.

  2. Small-World Propensity and Weighted Brain Networks

    Science.gov (United States)

    Muldoon, Sarah Feldt; Bridgeford, Eric W.; Bassett, Danielle S.

    2016-02-01

    Quantitative descriptions of network structure can provide fundamental insights into the function of interconnected complex systems. Small-world structure, diagnosed by high local clustering yet short average path length between any two nodes, promotes information flow in coupled systems, a key function that can differ across conditions or between groups. However, current techniques to quantify small-worldness are density dependent and neglect important features such as the strength of network connections, limiting their application in real-world systems. Here, we address both limitations with a novel metric called the Small-World Propensity (SWP). In its binary instantiation, the SWP provides an unbiased assessment of small-world structure in networks of varying densities. We extend this concept to the case of weighted brain networks by developing (i) a standardized procedure for generating weighted small-world networks, (ii) a weighted extension of the SWP, and (iii) a method for mapping observed brain network data onto the theoretical model. In applying these techniques to compare real-world brain networks, we uncover the surprising fact that the canonical biological small-world network, the C. elegans neuronal network, has strikingly low SWP. These metrics, models, and maps form a coherent toolbox for the assessment and comparison of architectural properties in brain networks.

  3. Small-world brain networks in schizophrenia

    Institute of Scientific and Technical Information of China (English)

    Mingli LI; Zhuangfei CHEN; Tao LI

    2012-01-01

    Over the last decade the combination of brain neuroimaging techniques and graph theoretical analysis of the complex anatomical and functional networks in the brain have provided an exciting new platform for exploring the etiology of mental disorders such as schizophrenia. This review introduces the current status of this work, focusing on these networks in schizophrenia. The evidence supporting the findings of reduced efficiency of information exchange in schizophrenia both within local brain regions and globally throughout the brain is reviewed and the potential relationship of these changes to cognitive and clinical symptoms is discussed. Finally we propose some suggestions for future research.

  4. The Efficiency of a Small-World Functional Brain Network

    Institute of Scientific and Technical Information of China (English)

    ZHAO Qing-Bai; ZHANG Xiao-Fei; SUI Dan-Ni; ZHOU Zhi-Jin; CHEN Qi-Cai; TANG Yi-Yuan

    2012-01-01

    We investigate whether the small-world topology of a functional brain network means high information processing efficiency by calculating the correlation between the small-world measures of a functional brain network and behavioral reaction during an imagery task.Functional brain networks are constructed by multichannel eventrelated potential data,in which the electrodes are the nodes and the functional connectivities between them are the edges.The results show that the correlation between small-world measures and reaction time is task-specific,such that in global imagery,there is a positive correlation between the clustering coefficient and reaction time,while in local imagery the average path length is positively correlated with the reaction time.This suggests that the efficiency of a functional brain network is task-dependent.%We investigate whether the small-world topology of a functional brain network means high information processing efficiency by calculating the correlation between the small-world measures of a functional brain network and behavioral reaction during an imagery task. Functional brain networks are constructed by multichannel event-related potential data, in which the electrodes are the nodes and the functional connectivities between them are the edges. The results show that the correlation between small-world measures and reaction time is task-specific, such that in global imagery, there is a positive correlation between the clustering coefficient and reaction time, while in local imagery the average path length is positively correlated with the reaction time. This suggests that the efficiency of a functional brain network is task-dependent.

  5. The small-world organization of large-scale brain systems and relationships with subcortical structures.

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    Koziol, Leonard F; Barker, Lauren A; Joyce, Arthur W; Hrin, Skip

    2014-01-01

    Brain structure and function is characterized by large-scale brain systems. However, each system has its own "small-world" organization, with sub-regions, or "hubs," that have varying degrees of specialization for certain cognitive and behavioral processes. This article describes this small-world organization, and the concepts of functional specialization and functional integration are defined and explained through practical examples. We also describe the development of large-scale brain systems and this small-world organization as a sensitive, protracted process, vulnerable to a variety of influences that generate neurodevelopmental disorders.

  6. The conundrum of functional brain networks: small-world or fractal modularity

    CERN Document Server

    Gallos, Lazaros K; Sigman, Mariano

    2011-01-01

    The human brain is organized in functional modules. Such an organization poses a conundrum: modules ought to be sufficiently independent to guarantee functional specialization and sufficiently connected to bind multiple processors for efficient information transfer. It is commonly accepted that small-world architecture may solve this problem. However, there is intrinsic tension between shortcuts generating small-worlds and the persistence of modules. Here we provide a solution to this puzzle. We show that the functional brain network formed by percolation of strong links is highly modular. Contrary to the common view, modules are self-similar and therefore are very far from being small-world. Incorporating the weak ties to the network converts it into a small-world preserving an underlying backbone of well-defined modules. Weak ties are organized precisely as predicted by theory maximizing information transfer with minimal wiring costs. This trade-off architecture is reminiscent of the "strength of weak ties"...

  7. Graph analysis of structural brain networks in Alzheimer's disease: beyond small world properties.

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    John, Majnu; Ikuta, Toshikazu; Ferbinteanu, Janina

    2017-03-01

    Changes in brain connectivity in patients with early Alzheimer's disease (AD) have been investigated using graph analysis. However, these studies were based on small data sets, explored a limited range of network parameters, and did not focus on more restricted sub-networks, where neurodegenerative processes may introduce more prominent alterations. In this study, we constructed structural brain networks out of 87 regions using data from 135 healthy elders and 100 early AD patients selected from the Open Access Series of Imaging Studies (OASIS) database. We evaluated the graph properties of these networks by investigating metrics of network efficiency, small world properties, segregation, product measures of complexity, and entropy. Because degenerative processes take place at different rates in different brain areas, analysis restricted to sub-networks may reveal changes otherwise undetected. Therefore, we first analyzed the graph properties of a network encompassing all brain areas considered together, and then repeated the analysis after dividing the brain areas into two sub-networks constructed by applying a clustering algorithm. At the level of large scale network, the analysis did not reveal differences between AD patients and controls. In contrast, the same analysis performed on the two sub-networks revealed that small worldness diminished with AD only in the sub-network containing the areas of medial temporal lobe known to be heaviest and earliest affected. The second sub-network, which did not present significant AD-induced modifications of 'classical' small world parameters, nonetheless showed a trend towards an increase in small world propensity, a novel metric that unbiasedly quantifies small world structure. Beyond small world properties, complexity and entropy measures indicated that the intricacy of connection patterns and structural diversity decreased in both sub-networks. These results show that neurodegenerative processes impact volumetric

  8. Enhanced brain small-worldness after sleep deprivation: a compensatory effect.

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    Liu, Huan; Li, Hong; Wang, Yulin; Lei, Xu

    2014-10-01

    Sleep deprivation has a variable impact on extrinsic activities during multiple cognitive tasks, especially on mood and emotion processing. There is also a trait-like individual vulnerability or compensatory effect in cognition. Previous studies have elucidated the altered functional connectivity after sleep deprivation. However, it remains unclear whether the small-world properties of resting-state network are sensitive to sleep deprivation. A small-world network is a type of graph that combines a high local connectivity as well as a few long-range connections, which ensures a higher information-processing efficiency at a low cost. The complex network of the brain can be described as a small-world network, in which a node is a brain region and an edge is present when there is a functional correlation between two nodes. Here, we investigated the topological properties of the human brain networks of 22 healthy subjects under sufficient sleep and sleep-deprived conditions. Specifically, small-worldness is utilized to quantify the small-world property, by comparing the clustering coefficient and path length of a given network to an equivalent random network with same degree distribution. After sufficient sleep, the brain networks showed the property of small-worldness. Compared with the resting state under sufficient sleep, the small-world property was significantly enhanced in the sleep deprivation condition, suggesting a possible compensatory adaptation of the human brain. Specifically, the altered measurements were correlated with the neuroticism of subjects, indicating that individuals with low-levels of neuroticism are more resilient to sleep deprivation.

  9. Driving and driven architectures of directed small-world human brain functional networks.

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    Chaogan Yan

    Full Text Available Recently, increasing attention has been focused on the investigation of the human brain connectome that describes the patterns of structural and functional connectivity networks of the human brain. Many studies of the human connectome have demonstrated that the brain network follows a small-world topology with an intrinsically cohesive modular structure and includes several network hubs in the medial parietal regions. However, most of these studies have only focused on undirected connections between regions in which the directions of information flow are not taken into account. How the brain regions causally influence each other and how the directed network of human brain is topologically organized remain largely unknown. Here, we applied linear multivariate Granger causality analysis (GCA and graph theoretical approaches to a resting-state functional MRI dataset with a large cohort of young healthy participants (n = 86 to explore connectivity patterns of the population-based whole-brain functional directed network. This directed brain network exhibited prominent small-world properties, which obviously improved previous results of functional MRI studies showing weak small-world properties in the directed brain networks in terms of a kernel-based GCA and individual analysis. This brain network also showed significant modular structures associated with 5 well known subsystems: fronto-parietal, visual, paralimbic/limbic, subcortical and primary systems. Importantly, we identified several driving hubs predominantly located in the components of the attentional network (e.g., the inferior frontal gyrus, supplementary motor area, insula and fusiform gyrus and several driven hubs predominantly located in the components of the default mode network (e.g., the precuneus, posterior cingulate gyrus, medial prefrontal cortex and inferior parietal lobule. Further split-half analyses indicated that our results were highly reproducible between two

  10. The conundrum of functional brain networks: small-world efficiency or fractal modularity

    CERN Document Server

    Gallos, Lazaros K; Makse, Hernan A

    2012-01-01

    The human brain has been studied at multiple scales, from neurons, circuits, areas with well defined anatomical and functional boundaries, to large-scale functional networks which mediate coherent cognition. In a recent work, we addressed the problem of the hierarchical organization in the brain through network analysis. Our analysis identified functional brain modules of fractal structure that were inter-connected in a small-world topology. Here, we provide more details on the use of network science tools to elaborate on this behavior. We indicate the importance of using percolation theory to highlight the modular character of the functional brain network. These modules present a fractal, self-similar topology, identified through fractal network methods. When we lower the threshold of correlations to include weaker ties, the network as a whole assumes a small-world character. These weak ties are organized precisely as predicted by theory maximizing information transfer with minimal wiring costs.

  11. Small-world anatomical networks in the human brain revealed by cortical thickness from MRI.

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    He, Yong; Chen, Zhang J; Evans, Alan C

    2007-10-01

    An important issue in neuroscience is the characterization for the underlying architectures of complex brain networks. However, little is known about the network of anatomical connections in the human brain. Here, we investigated large-scale anatomical connection patterns of the human cerebral cortex using cortical thickness measurements from magnetic resonance images. Two areas were considered anatomically connected if they showed statistically significant correlations in cortical thickness and we constructed the network of such connections using 124 brains from the International Consortium for Brain Mapping database. Significant short- and long-range connections were found in both intra- and interhemispheric regions, many of which were consistent with known neuroanatomical pathways measured by human diffusion imaging. More importantly, we showed that the human brain anatomical network had robust small-world properties with cohesive neighborhoods and short mean distances between regions that were insensitive to the selection of correlation thresholds. Additionally, we also found that this network and the probability of finding a connection between 2 regions for a given anatomical distance had both exponentially truncated power-law distributions. Our results demonstrated the basic organizational principles for the anatomical network in the human brain compatible with previous functional networks studies, which provides important implications of how functional brain states originate from their structural underpinnings. To our knowledge, this study provides the first report of small-world properties and degree distribution of anatomical networks in the human brain using cortical thickness measurements.

  12. Disrupted small-world brain networks in moderate Alzheimer's disease: a resting-state FMRI study.

    Directory of Open Access Journals (Sweden)

    Xiaohu Zhao

    Full Text Available The small-world organization has been hypothesized to reflect a balance between local processing and global integration in the human brain. Previous multimodal imaging studies have consistently demonstrated that the topological architecture of the brain network is disrupted in Alzheimer's disease (AD. However, these studies have reported inconsistent results regarding the topological properties of brain alterations in AD. One potential explanation for these inconsistent results lies with the diverse homogeneity and distinct progressive stages of the AD involved in these studies, which are thought to be critical factors that might affect the results. We investigated the topological properties of brain functional networks derived from resting functional magnetic resonance imaging (fMRI of carefully selected moderate AD patients and normal controls (NCs. Our results showed that the topological properties were found to be disrupted in AD patients, which showing increased local efficiency but decreased global efficiency. We found that the altered brain regions are mainly located in the default mode network, the temporal lobe and certain subcortical regions that are closely associated with the neuropathological changes in AD. Of note, our exploratory study revealed that the ApoE genotype modulates brain network properties, especially in AD patients.

  13. Small-world bias of correlation networks: From brain to climate

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    Hlinka, Jaroslav; Hartman, David; Jajcay, Nikola; Tomeček, David; Tintěra, Jaroslav; Paluš, Milan

    2017-03-01

    Complex systems are commonly characterized by the properties of their graph representation. Dynamical complex systems are then typically represented by a graph of temporal dependencies between time series of state variables of their subunits. It has been shown recently that graphs constructed in this way tend to have relatively clustered structure, potentially leading to spurious detection of small-world properties even in the case of systems with no or randomly distributed true interactions. However, the strength of this bias depends heavily on a range of parameters and its relevance for real-world data has not yet been established. In this work, we assess the relevance of the bias using two examples of multivariate time series recorded in natural complex systems. The first is the time series of local brain activity as measured by functional magnetic resonance imaging in resting healthy human subjects, and the second is the time series of average monthly surface air temperature coming from a large reanalysis of climatological data over the period 1948-2012. In both cases, the clustering in the thresholded correlation graph is substantially higher compared with a realization of a density-matched random graph, while the shortest paths are relatively short, showing thus distinguishing features of small-world structure. However, comparable or even stronger small-world properties were reproduced in correlation graphs of model processes with randomly scrambled interconnections. This suggests that the small-world properties of the correlation matrices of these real-world systems indeed do not reflect genuinely the properties of the underlying interaction structure, but rather result from the inherent properties of correlation matrix.

  14. Mapping small-world properties through development in the human brain: disruption in schizophrenia.

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    Dardo Tomasi

    Full Text Available Evidence from imaging studies suggests that the human brain has a small-world network topology that might be disrupted in certain brain disorders. However, current methodology is based on global graph theory measures, such as clustering, C, characteristic path length, L, and small-worldness, S, that lack spatial specificity and are insufficient to identify regional brain abnormalities. Here we propose novel ultra-fast methodology for mapping local properties of brain network topology such as local C, L and S (lC, lL and lS in the human brain at 3-mm isotropic resolution from 'resting-state' magnetic resonance imaging data. Test-retest datasets from 40 healthy children/adolescents were used to demonstrate the overall good reliability of the measures across sessions and computational parameters (intraclass correlation > 0.5 for lC and lL and their low variability across subjects (< 29%. Whereas regions with high local functional connectivity density (lFCD; local degree in posterior parietal and occipital cortices demonstrated high lC and short lL, subcortical regions (globus pallidus, thalamus, hippocampus and amygdala, cerebellum (lobes and vermis, cingulum and temporal cortex also had high, lS, demonstrating stronger small-world topology than other hubs. Children/adolescents had stronger lFCD, higher lC and longer lL in most cortical regions and thalamus than 74 healthy adults, consistent with pruning of functional connectivity during maturation. In contrast, lFCD, lC and lL were weaker in thalamus and midbrain, and lL was shorter in frontal cortical regions and cerebellum for 69 schizophrenia patients than for 74 healthy controls, suggesting exaggerated pruning of connectivity in schizophrenia. Follow up correlation analyses for seeds in thalamus and midbrain uncovered lower positive connectivity of these regions in thalamus, putamen, cerebellum and frontal cortex (cingulum, orbitofrontal, inferior frontal and lower negative connectivity in

  15. Altered small-world brain networks in schizophrenia patients during working memory performance.

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    He, Hao; Sui, Jing; Yu, Qingbao; Turner, Jessica A; Ho, Beng-Choon; Sponheim, Scott R; Manoach, Dara S; Clark, Vincent P; Calhoun, Vince D

    2012-01-01

    Impairment of working memory (WM) performance in schizophrenia patients (SZ) is well-established. Compared to healthy controls (HC), SZ patients show aberrant blood oxygen level dependent (BOLD) activations and disrupted functional connectivity during WM performance. In this study, we examined the small-world network metrics computed from functional magnetic resonance imaging (fMRI) data collected as 35 HC and 35 SZ performed a Sternberg Item Recognition Paradigm (SIRP) at three WM load levels. Functional connectivity networks were built by calculating the partial correlation on preprocessed time courses of BOLD signal between task-related brain regions of interest (ROIs) defined by group independent component analysis (ICA). The networks were then thresholded within the small-world regime, resulting in undirected binarized small-world networks at different working memory loads. Our results showed: 1) at the medium WM load level, the networks in SZ showed a lower clustering coefficient and less local efficiency compared with HC; 2) in SZ, most network measures altered significantly as the WM load level increased from low to medium and from medium to high, while the network metrics were relatively stable in HC at different WM loads; and 3) the altered structure at medium WM load in SZ was related to their performance during the task, with longer reaction time related to lower clustering coefficient and lower local efficiency. These findings suggest brain connectivity in patients with SZ was more diffuse and less strongly linked locally in functional network at intermediate level of WM when compared to HC. SZ show distinctly inefficient and variable network structures in response to WM load increase, comparing to stable highly clustered network topologies in HC.

  16. Altered small-world brain networks in schizophrenia patients during working memory performance.

    Directory of Open Access Journals (Sweden)

    Hao He

    Full Text Available Impairment of working memory (WM performance in schizophrenia patients (SZ is well-established. Compared to healthy controls (HC, SZ patients show aberrant blood oxygen level dependent (BOLD activations and disrupted functional connectivity during WM performance. In this study, we examined the small-world network metrics computed from functional magnetic resonance imaging (fMRI data collected as 35 HC and 35 SZ performed a Sternberg Item Recognition Paradigm (SIRP at three WM load levels. Functional connectivity networks were built by calculating the partial correlation on preprocessed time courses of BOLD signal between task-related brain regions of interest (ROIs defined by group independent component analysis (ICA. The networks were then thresholded within the small-world regime, resulting in undirected binarized small-world networks at different working memory loads. Our results showed: 1 at the medium WM load level, the networks in SZ showed a lower clustering coefficient and less local efficiency compared with HC; 2 in SZ, most network measures altered significantly as the WM load level increased from low to medium and from medium to high, while the network metrics were relatively stable in HC at different WM loads; and 3 the altered structure at medium WM load in SZ was related to their performance during the task, with longer reaction time related to lower clustering coefficient and lower local efficiency. These findings suggest brain connectivity in patients with SZ was more diffuse and less strongly linked locally in functional network at intermediate level of WM when compared to HC. SZ show distinctly inefficient and variable network structures in response to WM load increase, comparing to stable highly clustered network topologies in HC.

  17. Altered topological properties of functional network connectivity in schizophrenia during resting state: a small-world brain network study.

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    Yu, Qingbao; Sui, Jing; Rachakonda, Srinivas; He, Hao; Gruner, William; Pearlson, Godfrey; Kiehl, Kent A; Calhoun, Vince D

    2011-01-01

    Aberrant topological properties of small-world human brain networks in patients with schizophrenia (SZ) have been documented in previous neuroimaging studies. Aberrant functional network connectivity (FNC, temporal relationships among independent component time courses) has also been found in SZ by a previous resting state functional magnetic resonance imaging (fMRI) study. However, no study has yet determined if topological properties of FNC are also altered in SZ. In this study, small-world network metrics of FNC during the resting state were examined in both healthy controls (HCs) and SZ subjects. FMRI data were obtained from 19 HCs and 19 SZ. Brain images were decomposed into independent components (ICs) by group independent component analysis (ICA). FNC maps were constructed via a partial correlation analysis of ICA time courses. A set of undirected graphs were built by thresholding the FNC maps and the small-world network metrics of these maps were evaluated. Our results demonstrated significantly altered topological properties of FNC in SZ relative to controls. In addition, topological measures of many ICs involving frontal, parietal, occipital and cerebellar areas were altered in SZ relative to controls. Specifically, topological measures of whole network and specific components in SZ were correlated with scores on the negative symptom scale of the Positive and Negative Symptom Scale (PANSS). These findings suggest that aberrant architecture of small-world brain topology in SZ consists of ICA temporally coherent brain networks.

  18. From brain to earth and climate systems: small-world interaction networks or not?

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    Bialonski, Stephan; Horstmann, Marie-Therese; Lehnertz, Klaus

    2010-03-01

    We consider recent reports on small-world topologies of interaction networks derived from the dynamics of spatially extended systems that are investigated in diverse scientific fields such as neurosciences, geophysics, or meteorology. With numerical simulations that mimic typical experimental situations, we have identified an important constraint when characterizing such networks: indications of a small-world topology can be expected solely due to the spatial sampling of the system along with the commonly used time series analysis based approaches to network characterization.

  19. Beyond Scale-Free Small-World Networks: Cortical Columns for Quick Brains

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    Stoop, Ralph; Saase, Victor; Wagner, Clemens; Stoop, Britta; Stoop, Ruedi

    2013-03-01

    We study to what extent cortical columns with their particular wiring boost neural computation. Upon a vast survey of columnar networks performing various real-world cognitive tasks, we detect no signs of enhancement. It is on a mesoscopic—intercolumnar—scale that the existence of columns, largely irrespective of their inner organization, enhances the speed of information transfer and minimizes the total wiring length required to bind distributed columnar computations towards spatiotemporally coherent results. We suggest that brain efficiency may be related to a doubly fractal connectivity law, resulting in networks with efficiency properties beyond those by scale-free networks.

  20. Altered small-world efficiency of brain functional networks in acupuncture at ST36: a functional MRI study.

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    Bo Liu

    Full Text Available BACKGROUND: Acupuncture in humans can produce clinical effects via the central nervous system. However, the neural substrates of acupuncture's effects remain largely unknown. RESULTS: We utilized functional MRI to investigate the topological efficiency of brain functional networks in eighteen healthy young adults who were scanned before and after acupuncture at the ST36 acupoints (ACUP and its sham point (SHAM. Whole-brain functional networks were constructed by thresholding temporal correlations matrices of ninety brain regions, followed by a graph theory-based analysis. We showed that brain functional networks exhibited small-world attributes (high local and global efficiency regardless of the order of acupuncture and stimulus points, a finding compatible with previous studies of brain functional networks. Furthermore, the brain networks had increased local efficiency after ACUP stimulation but there were no significant differences after SHAM, indicating a specificity of acupuncture point in coordinating local information flow over the whole brain. Moreover, significant (P<0.05, corrected by false discovery rate approach effects of only acupuncture point were detected on nodal degree of the left hippocampus (higher nodal degree at ACUP as compared to SHAM. Using an uncorrected P<0.05, point-related effects were also observed in the anterior cingulate cortex, frontal and occipital regions while stimulation-related effects in various brain regions of frontal, parietal and occipital cortex regions. In addition, we found that several limbic and subcortical brain regions exhibited point- and stimulation-related alterations in their regional homogeneity (P<0.05, uncorrected. CONCLUSIONS: Our results suggest that acupuncture modulates topological organization of whole-brain functional brain networks and the modulation has point specificity. These findings provide new insights into neuronal mechanism of acupuncture from the perspective of functional

  1. Small-World Brain Functional Networks in Children With Attention-Deficit/Hyperactivity Disorder Revealed by EEG Synchrony.

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    Liu, Tian; Chen, Yanni; Lin, Pan; Wang, Jue

    2015-07-01

    We investigated the topologic properties of human brain attention-related functional networks associated with Multi-Source Interference Task (MSIT) performance using electroencephalography (EEG). Data were obtained from 13 children diagnosed with attention-deficit/hyperactivity disorder (ADHD) and 13 normal control children. Functional connectivity between all pairwise combinations of EEG channels was established by calculating synchronization likelihood (SL). The cluster coefficients and path lengths were computed as a function of degree K. The results showed that brain attention functional networks of normal control subjects had efficient small-world topologic properties, whereas these topologic properties were altered in ADHD. In particular, increased local characteristics combined with decreased global characteristics in ADHD led to a disorder-related shift of the network topologic structure toward ordered networks. These findings are consistent with a hypothesis of dysfunctional segregation and integration of the brain in ADHD, and enhance our understanding of the underlying pathophysiologic mechanism of this illness.

  2. Hemisphere- and gender-related differences in small-world brain networks: a resting-state functional MRI study.

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    Tian, Lixia; Wang, Jinhui; Yan, Chaogan; He, Yong

    2011-01-01

    We employed resting-state functional MRI (R-fMRI) to investigate hemisphere- and gender-related differences in the topological organization of human brain functional networks. Brain networks were first constructed by measuring inter-regional temporal correlations of R-fMRI data within each hemisphere in 86 young, healthy, right-handed adults (38 males and 48 females) followed by a graph-theory analysis. The hemispheric networks exhibit small-world attributes (high clustering and short paths) that are compatible with previous results in the whole-brain functional networks. Furthermore, we found that compared with females, males have a higher normalized clustering coefficient in the right hemispheric network but a lower clustering coefficient in the left hemispheric network, suggesting a gender-hemisphere interaction. Moreover, we observed significant hemisphere-related differences in the regional nodal characteristics in various brain regions, such as the frontal and occipital regions (leftward asymmetry) and the temporal regions (rightward asymmetry), findings that are consistent with previous studies of brain structural and functional asymmetries. Together, our results suggest that the topological organization of human brain functional networks is associated with gender and hemispheres, and they provide insights into the understanding of functional substrates underlying individual differences in behaviors and cognition.

  3. Handedness- and brain size-related efficiency differences in small-world brain networks: a resting-state functional magnetic resonance imaging study.

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    Li, Meiling; Wang, Junping; Liu, Feng; Chen, Heng; Lu, Fengmei; Wu, Guorong; Yu, Chunshui; Chen, Huafu

    2015-05-01

    The human brain has been described as a complex network, which integrates information with high efficiency. However, the relationships between the efficiency of human brain functional networks and handedness and brain size remain unclear. Twenty-one left-handed and 32 right-handed healthy subjects underwent a resting-state functional magnetic resonance imaging scan. The whole brain functional networks were constructed by thresholding Pearson correlation matrices of 90 cortical and subcortical regions. Graph theory-based methods were employed to further analyze their topological properties. As expected, all participants demonstrated small-world topology, suggesting a highly efficient topological structure. Furthermore, we found that smaller brains showed higher local efficiency, whereas larger brains showed higher global efficiency, reflecting a suitable efficiency balance between local specialization and global integration of brain functional activity. Compared with right-handers, significant alterations in nodal efficiency were revealed in left-handers, involving the anterior and median cingulate gyrus, middle temporal gyrus, angular gyrus, and amygdala. Our findings indicated that the functional network organization in the human brain was associated with handedness and brain size.

  4. Disrupted Small-World Networks in Schizophrenia

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    Liu, Yong; Liang, Meng; Zhou, Yuan; He, Yong; Hao, Yihui; Song, Ming; Yu, Chunshui; Liu, Haihong; Liu, Zhening; Jiang, Tianzi

    2008-01-01

    The human brain has been described as a large, sparse, complex network characterized by efficient small-world properties, which assure that the brain generates and integrates information with high efficiency. Many previous neuroimaging studies have provided consistent evidence of "dysfunctional connectivity" among the brain regions in…

  5. Brain-machine interface control of a manipulator using small-world neural network and shared control strategy.

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    Li, Ting; Hong, Jun; Zhang, Jinhua; Guo, Feng

    2014-03-15

    The improvement of the resolution of brain signal and the ability to control external device has been the most important goal in BMI research field. This paper describes a non-invasive brain-actuated manipulator experiment, which defined a paradigm for the motion control of a serial manipulator based on motor imagery and shared control. The techniques of component selection, spatial filtering and classification of motor imagery were involved. Small-world neural network (SWNN) was used to classify five brain states. To verify the effectiveness of the proposed classifier, we replace the SWNN classifier by a radial basis function (RBF) networks neural network, a standard multi-layered feed-forward backpropagation network (SMN) and a multi-SVM classifier, with the same features for the classification. The results also indicate that the proposed classifier achieves a 3.83% improvement over the best results of other classifiers. We proposed a shared control method consisting of two control patterns to expand the control of BMI from the software angle. The job of path building for reaching the 'end' point was designated as an assessment task. We recorded all paths contributed by subjects and picked up relevant parameters as evaluation coefficients. With the assistance of two control patterns and series of machine learning algorithms, the proposed BMI originally achieved the motion control of a manipulator in the whole workspace. According to experimental results, we confirmed the feasibility of the proposed BMI method for 3D motion control of a manipulator using EEG during motor imagery. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Regular Small-World Network

    Institute of Scientific and Technical Information of China (English)

    ZOU Zhi-Yun; MAO Bao-Hua; HAO Hai-Ming; GAO Jian-Zhi; YANG Jie-Jiao

    2009-01-01

    According to the deficiencies in Watts and Strogatz's small-world network model, we present a new regular model to establish the small-world network. Besides the property of the small-world, this model has other properties such as accuracy in controlling the average shortest path length L, and the average clustering coefficient C, also regular network topology as well as enhanced network robustness. This method improves the construction of the small-world network essentially, so that the regular small-world network closely resembles the actual network. We also present studies on the relationships among the quantities of a variety of edges, L and C in regular small-world network in detail. This research lays the foundation for the establishment of the regular small-world network and acts as a good guidance for further research of this model and its applications.

  7. Economics: An Emerging Small World?

    NARCIS (Netherlands)

    S. Goyal (Sanjeev); M.J. van der Leij (Marco); J.L. Moraga-Gonzalez (José Luis)

    2004-01-01

    textabstractThis paper examines the small world hypothesis. The first part of the paper presents empirical evidence on the evolution of a particular world: the world of journal publishing economists during the period 1970-2000. We find that in the 1970's the world of economics was a collection of is

  8. Small-world and scale-free organization of voxel-based resting-state functional connectivity in the human brain.

    Science.gov (United States)

    van den Heuvel, M P; Stam, C J; Boersma, M; Hulshoff Pol, H E

    2008-11-15

    The brain is a complex dynamic system of functionally connected regions. Graph theory has been successfully used to describe the organization of such dynamic systems. Recent resting-state fMRI studies have suggested that inter-regional functional connectivity shows a small-world topology, indicating an organization of the brain in highly clustered sub-networks, combined with a high level of global connectivity. In addition, a few studies have investigated a possible scale-free topology of the human brain, but the results of these studies have been inconclusive. These studies have mainly focused on inter-regional connectivity, representing the brain as a network of brain regions, requiring an arbitrary definition of such regions. However, using a voxel-wise approach allows for the model-free examination of both inter-regional as well as intra-regional connectivity and might reveal new information on network organization. Especially, a voxel-based study could give information about a possible scale-free organization of functional connectivity in the human brain. Resting-state 3 Tesla fMRI recordings of 28 healthy subjects were acquired and individual connectivity graphs were formed out of all cortical and sub-cortical voxels with connections reflecting inter-voxel functional connectivity. Graph characteristics from these connectivity networks were computed. The clustering-coefficient of these networks turned out to be much higher than the clustering-coefficient of comparable random graphs, together with a short average path length, indicating a small-world organization. Furthermore, the connectivity distribution of the number of inter-voxel connections followed a power-law scaling with an exponent close to 2, suggesting a scale-free network topology. Our findings suggest a combined small-world and scale-free organization of the functionally connected human brain. The results are interpreted as evidence for a highly efficient organization of the functionally connected

  9. A Single Session of rTMS Enhances Small-Worldness in Writer’s Cramp: Evidence from Simultaneous EEG-fMRI Multi-Modal Brain Graph

    Directory of Open Access Journals (Sweden)

    Rose D. Bharath

    2017-09-01

    Full Text Available Background and Purpose: Repetitive transcranial magnetic stimulation (rTMS induces widespread changes in brain connectivity. As the network topology differences induced by a single session of rTMS are less known we undertook this study to ascertain whether the network alterations had a small-world morphology using multi-modal graph theory analysis of simultaneous EEG-fMRI.Method: Simultaneous EEG-fMRI was acquired in duplicate before (R1 and after (R2 a single session of rTMS in 14 patients with Writer’s Cramp (WC. Whole brain neuronal and hemodynamic network connectivity were explored using the graph theory measures and clustering coefficient, path length and small-world index were calculated for EEG and resting state fMRI (rsfMRI. Multi-modal graph theory analysis was used to evaluate the correlation of EEG and fMRI clustering coefficients.Result: A single session of rTMS was found to increase the clustering coefficient and small-worldness significantly in both EEG and fMRI (p < 0.05. Multi-modal graph theory analysis revealed significant modulations in the fronto-parietal regions immediately after rTMS. The rsfMRI revealed additional modulations in several deep brain regions including cerebellum, insula and medial frontal lobe.Conclusion: Multi-modal graph theory analysis of simultaneous EEG-fMRI can supplement motor physiology methods in understanding the neurobiology of rTMS in vivo. Coinciding evidence from EEG and rsfMRI reports small-world morphology for the acute phase network hyper-connectivity indicating changes ensuing low-frequency rTMS is probably not “noise”.

  10. Quantum Small-world Networks

    CERN Document Server

    Wei, Zong-Wen; Han, Xiao-Pu

    2011-01-01

    Quantum networks are critical to quantum communication and distributed quantum computing. Here we propose a small-world model of large-scale quantum repeater networks, where "small-world" is a fundamental concept rooted in complex networks, which describe a broad range of real systems. The core of the model is to relate the hierarchical fashion of measurements to coarse-graining process, when quantum repeater protocols are implemented. We demonstrate that quantum repeater networks with fractal structure can be enlarged with certain length scale in geographic space, while preserving topology by performing renormalization. Actually, renormalization here serves as an organizing principle determining the distribution of long-range entangled links over quantum networks, which gives rise to fractal to small-world transition. Furthermore, by iterative implementation of renormalization on the former coarse-grained network, we eventually obtain an onion-like, hierarchical quantum small-world network, where the distanc...

  11. 静息态人脑功能网络的小世界特性%Small-World Properties of Resting State Human Brain Functional Networks

    Institute of Scientific and Technical Information of China (English)

    黄文涛; 冯又层

    2011-01-01

    研究了静息态下健康人脑的功能连接模式有助于理解人脑在正常或疾病状态下的功能活动规律.利用小波变换从健康志愿者静息态的功能磁共振成像中提取时间序列,计算90个脑区的相关性,设定阈值建立脑功能网络的无向简单图,然后计算特征路径长度和聚类系数,并对度分布进行拟合.结果显示:脑功能网络具有规则网络的大聚集系数又具有随机网络的小特征路径长度,度的拟合显示具有指数截断幂律分布,即脑功能网络具有小世界特性.%It is important to study the resting state functional pattern of healthy human brain because it will aid us to understand the law of functional activities of human brain in normal or disease states.Using wavelet transformation,time series of 90 brain regions were extracted from functional magnetic resonance imagines of resting state healthy volunteers.Functional correlations between brain regions were calculated,and the threshold was set to establish the simple undirected graph,then characteristic path length and clustering coefficient were computed,finally the degree distribution was fitted.The results demonstrated that the brain functional networks had both big clustering coefficients like regular networks and small characteristic path lengths similar as random networks,degree distribution met exponentially truncated power-law distribution.Taken together,the human brain functional networks have small world properties.

  12. World Small Hydropower Development Report

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Heng; Esser, Lara (ICSGP (China)); Masera, Diego (UNIDO, Vienna (Austria))

    2013-07-01

    Currently, small hydropower plants with a capacity of 10 MW, exist in 148 countries or territories worldwide. Four other countries have been identified with resource potential. This report aims to identify the development status and resource potential of small hydro in various countries, territories and regions throughout the world. Working with experts at the ground level to compile and share existing information, experiences and challenges, one comprehensive report was created. Decision-makers, stakeholders and potential investors clearly need this comprehensive information to more effectively promote small hydropower as a renewable and rural energy source for sustainable development and to overcome the existing development barriers. The findings of this report show that small hydropower potential globally is approximated at almost 173 GW. The figure is arrived by totaling data from a wide range of sources with potential compromise of data integrity to varying degrees. For example, research data on economically feasible potential were more readily available in developed countries than those in the least developed or developing countries. More than half of the world's known hydropower potential is located in Asia, around one third can be found in Europe and the Americas. It is possible in the future that more small hydropower potential might be identified both on the African and American continents. The installed small hydropower capacity (up to 10 MW) is estimated to be 75 GW in 2011/2012. The report provides detailed data for each country/region, including recommendations on the national, regional and international level.

  13. Trust Propagation in Small Worlds

    DEFF Research Database (Denmark)

    Gray, Elizabeth; Seigneur, Jean-Marc; Chen, Yong

    2003-01-01

    The possibility of a massive, networked infrastructure of diverse entities partaking in collaborative applications with each other increases more and more with the proliferation of mobile devices and the development of ad hoc networking technologies. In this context, traditional security measures...... do not scale well. We aim to develop trust-based security mechanisms using small world concepts to optimise formation and propagation of trust amongst entities in these vast networks. In this regard, we surmise that in a very large mobile ad hoc network, trust, risk, and recommendations can...

  14. Small Worldness in Dense and Weighted Connectomes

    Science.gov (United States)

    Colon-Perez, Luis; Couret, Michelle; Triplett, William; Price, Catherine; Mareci, Thomas

    2016-05-01

    The human brain is a heterogeneous network of connected functional regions; however, most brain network studies assume that all brain connections can be described in a framework of binary connections. The brain is a complex structure of white matter tracts connected by a wide range of tract sizes, which suggests a broad range of connection strengths. Therefore, the assumption that the connections are binary yields an incomplete picture of the brain. Various thresholding methods have been used to remove spurious connections and reduce the graph density in binary networks. But these thresholds are arbitrary and make problematic the comparison of networks created at different thresholds. The heterogeneity of connection strengths can be represented in graph theory by applying weights to the network edges. Using our recently introduced edge weight parameter, we estimated the topological brain network organization using a complimentary weighted connectivity framework to the traditional framework of a binary network. To examine the reproducibility of brain networks in a controlled condition, we studied the topological network organization of a single healthy individual by acquiring 10 repeated diffusion-weighted magnetic resonance image datasets, over a one-month period on the same scanner, and analyzing these networks with deterministic tractography. We applied a threshold to both the binary and weighted networks and determined that the extra degree of freedom that comes with the framework of weighting network connectivity provides a robust result as any threshold level. The proposed weighted connectivity framework provides a stable result and is able to demonstrate the small world property of brain networks in situations where the binary framework is inadequate and unable to demonstrate this network property.

  15. Small-world networks in neuronal populations: a computational perspective.

    Science.gov (United States)

    Zippo, Antonio G; Gelsomino, Giuliana; Van Duin, Pieter; Nencini, Sara; Caramenti, Gian Carlo; Valente, Maurizio; Biella, Gabriele E M

    2013-08-01

    The analysis of the brain in terms of integrated neural networks may offer insights on the reciprocal relation between structure and information processing. Even with inherent technical limits, many studies acknowledge neuron spatial arrangements and communication modes as key factors. In this perspective, we investigated the functional organization of neuronal networks by explicitly assuming a specific functional topology, the small-world network. We developed two different computational approaches. Firstly, we asked whether neuronal populations actually express small-world properties during a definite task, such as a learning task. For this purpose we developed the Inductive Conceptual Network (ICN), which is a hierarchical bio-inspired spiking network, capable of learning invariant patterns by using variable-order Markov models implemented in its nodes. As a result, we actually observed small-world topologies during learning in the ICN. Speculating that the expression of small-world networks is not solely related to learning tasks, we then built a de facto network assuming that the information processing in the brain may occur through functional small-world topologies. In this de facto network, synchronous spikes reflected functional small-world network dependencies. In order to verify the consistency of the assumption, we tested the null-hypothesis by replacing the small-world networks with random networks. As a result, only small world networks exhibited functional biomimetic characteristics such as timing and rate codes, conventional coding strategies and neuronal avalanches, which are cascades of bursting activities with a power-law distribution. Our results suggest that small-world functional configurations are liable to underpin brain information processing at neuronal level.

  16. Epidemics in interconnected small-world networks

    NARCIS (Netherlands)

    Liu, M.; Li, D.; Qin, P.; Liu, C.; Wang, H.; Wang, F.

    2015-01-01

    Networks can be used to describe the interconnections among individuals, which play an important role in the spread of disease. Although the small-world effect has been found to have a significant impact on epidemics in single networks, the small-world effect on epidemics in interconnected networks

  17. Economics : An emerging small world

    NARCIS (Netherlands)

    Goyal, S; van der Leij, MJ; Moraga-Gonzalez, JL

    2006-01-01

    We study the evolution of social distance among economists over the period 1970-2000. While the number of economists has more than doubled, the distance between them, which was already small, has declined significantly. The key to understanding the short average distances is the observation that eco

  18. Population synchrony in small-world networks.

    Science.gov (United States)

    Ranta, Esa; Fowler, Mike S; Kaitala, Veijo

    2008-02-22

    Network topography ranges from regular graphs (linkage between nearest neighbours only) via small-world graphs (some random connections between nodes) to completely random graphs. Small-world linkage is seen as a revolutionary architecture for a wide range of social, physical and biological networks, and has been shown to increase synchrony between oscillating subunits. We study small-world topographies in a novel context: dispersal linkage between spatially structured populations across a range of population models. Regular dispersal between population patches interacting with density-dependent renewal provides one ecological explanation for the large-scale synchrony seen in the temporal fluctuations of many species, for example, lynx populations in North America, voles in Fennoscandia and grouse in the UK. Introducing a small-world dispersal kernel leads to a clear reduction in synchrony with both increasing dispersal rate and small-world dispersal probability across a variety of biological scenarios. Synchrony is also reduced when populations are affected by globally correlated noise. We discuss ecological implications of small-world dispersal in the frame of spatial synchrony in population fluctuations.

  19. The ubiquity of small-world networks

    CERN Document Server

    Telesford, Qawi K; Hayasaka, Satoru; Burdette, Jonathan H; Laurienti, Paul J

    2011-01-01

    Small-world networks by Watts and Strogatz are a class of networks that are highly clustered, like regular lattices, yet have small characteristic path lengths, like random graphs. These characteristics result in networks with unique properties of regional specialization with efficient information transfer. Social networks are intuitive examples of this organization with cliques or clusters of friends being interconnected, but each person is really only 5-6 people away from anyone else. While this qualitative definition has prevailed in network science theory, in application, the standard quantitative application is to compare path length (a surrogate measure of distributed processing) and clustering (a surrogate measure of regional specialization) to an equivalent random network. It is demonstrated here that comparing network clustering to that of a random network can result in aberrant findings and networks once thought to exhibit small-world properties may not. We propose a new small-world metric, {\\omega}...

  20. Scaling in small-world resistor networks

    Energy Technology Data Exchange (ETDEWEB)

    Korniss, G. [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180-3590 (United States)]. E-mail: korniss@rpi.edu; Hastings, M.B. [Center for Non-linear Studies and Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bassler, K.E. [Department of Physics, 617 Science and Research Blvd I, Univesity of Houston, Houston, TX 77204-5005 (United States); Berryman, M.J. [Centre for Biomedical Engineering (CBME) and School of Electrical and Electronic Engineering, The University of Adelaide, SA 5005 (Australia); Kozma, B. [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180-3590 (United States); Abbott, D. [Centre for Biomedical Engineering (CBME) and School of Electrical and Electronic Engineering, The University of Adelaide, SA 5005 (Australia)

    2006-02-13

    We study the effective resistance of small-world resistor networks. Utilizing recent analytic results for the propagator of the Edwards-Wilkinson process on small-world networks, we obtain the asymptotic behavior of the disorder-averaged two-point resistance in the large system-size limit. We find that the small-world structure suppresses large network resistances: both the average resistance and its standard deviation approaches a finite value in the large system-size limit for any non-zero density of random links. We also consider a scenario where the link conductance decays as a power of the length of the random links, l{sup -{alpha}}. In this case we find that the average effective system resistance diverges for any non-zero value of {alpha}.

  1. Small-world networks on a sphere

    Science.gov (United States)

    Corso, Gilberto; Torres Cruz, Claudia P.

    2017-01-01

    The Small-World Network on a Sphere SWNS is a non-crossing network that has no hubs and presents the small-world property diam log N with diam being the maximal distance between any two vertices and N being the number of vertices. The SWNS is constructed using a partition of the sphere and the parallels are regular sections of the sphere with constant latitude. The number of cells on the parallels, however, increases exponentially from the pole to the equator of the sphere. We analytically compute the distribution of connectivity, the clustering coefficient and the SWNS distances. The resilience of the model against selective attacks is also discussed.

  2. Small-world ProPerties of the brain structural networks in male schizoPhrenia%男性精神分裂症患者脑结构网络小世界属性研究

    Institute of Scientific and Technical Information of China (English)

    李影; 陈建淮; 阎锐; 花玲玲; 姚志剑

    2014-01-01

    目的:探讨男性精神分裂症患者脑结构网络小世界属性的特点。方法:对21例男性精神分裂症患者(患者组)进行弥散张量成像扫描(DTI),利用解剖学自动标记模板(AAL)将整个大脑划分为90个区域,采用纤维分配连续跟踪(FACT)方法构建脑结构二值网络;并与23名健康男性(对照组)比较。结果:两组脑结构网络均具有小世界属性(P =0.47);患者组平均最短路径长度较对照组显著增加(P =0.001),经 FDR 校正主要位于右侧颞中回、左侧楔叶、右侧枕中回、左侧扣带回后部、右侧颞上回颞极、右侧颞中回颞极(P 均﹤0.001)。结论:男性精神分裂症患者脑结构形式和信息处理模式都具有小世界属性;但不同脑区间信息传递路径变长,提示其脑结构网络信息传递能力和脑区间信息整合能力受损。%To explore the characteristics of the small-world properties of the brain structural networks in male schizophrenia. Method:Twenty-one male schizophrenic patients(case group)were scanned with diffusion tensor imaging(DTI). The whole brain was divided into 90 districts by automated anatomical la-beling(AAL),and brain structure binary network was constructed by fiber distribution of continuous tracking (FACT)method. The result was compared with 23 healthy men(control group). Results:The brain struc-tural networks had small-world properties in both groups(P = 0. 47). The average shortest path length of the brain structural networks in case group was significantly increased than the control group(P = 0. 001). By the correction of FDR,mainly in the right middle temporal gyrus,the left cuneus,the right middle occipital gyrus, the left median cingulate gyri,the right superior temporal gyrus(temporal pole)and the right middle temporal gyrus(temporal pole). Conclusion:The brain structure form and the information processing model in male schizophrenic patients

  3. World Small Hydropower Development Report 2013 - Zimbabwe

    CSIR Research Space (South Africa)

    Jonker Klunne, W

    2013-01-01

    Full Text Available , H., Masera, D. and Esser, L., eds. (2013). World Small Hydropower Development Report 2013. United Nations Industrial Development Organization; International Center on Small Hydro Power. Available from www.smallhydroworld.org. Disclaimer 1 1 Africa... 1.1 Eastern Africa 1.1.14 Zimbabwe Wim Jonker Klunne, Council for Scientific and Industrial Research, South Africa Key facts Population 12,619,600 1 Area 390,759 km 2 Climate Tropical; moderated by altitude 1 Topography Mostly high...

  4. Altered small-world topology of structural brain networks in infants with intrauterine growth restriction and its association with later neurodevelopmental outcome.

    Science.gov (United States)

    Batalle, Dafnis; Eixarch, Elisenda; Figueras, Francesc; Muñoz-Moreno, Emma; Bargallo, Nuria; Illa, Miriam; Acosta-Rojas, Ruthy; Amat-Roldan, Ivan; Gratacos, Eduard

    2012-04-02

    Intrauterine growth restriction (IUGR) due to placental insufficiency affects 5-10% of all pregnancies and it is associated with a wide range of short- and long-term neurodevelopmental disorders. Prediction of neurodevelopmental outcomes in IUGR is among the clinical challenges of modern fetal medicine and pediatrics. In recent years several studies have used magnetic resonance imaging (MRI) to demonstrate differences in brain structure in IUGR subjects, but the ability to use MRI for individual predictive purposes in IUGR is limited. Recent research suggests that MRI in vivo access to brain connectivity might have the potential to help understanding cognitive and neurodevelopment processes. Specifically, MRI based connectomics is an emerging approach to extract information from MRI data that exhaustively maps inter-regional connectivity within the brain to build a graph model of its neural circuitry known as brain network. In the present study we used diffusion MRI based connectomics to obtain structural brain networks of a prospective cohort of one year old infants (32 controls and 24 IUGR) and analyze the existence of quantifiable brain reorganization of white matter circuitry in IUGR group by means of global and regional graph theory features of brain networks. Based on global and regional analyses of the brain network topology we demonstrated brain reorganization in IUGR infants at one year of age. Specifically, IUGR infants presented decreased global and local weighted efficiency, and a pattern of altered regional graph theory features. By means of binomial logistic regression, we also demonstrated that connectivity measures were associated with abnormal performance in later neurodevelopmental outcome as measured by Bayley Scale for Infant and Toddler Development, Third edition (BSID-III) at two years of age. These findings show the potential of diffusion MRI based connectomics and graph theory based network characteristics for estimating differences in the

  5. The problem of thresholding in small-world network analysis.

    Directory of Open Access Journals (Sweden)

    Nicolas Langer

    Full Text Available Graph theory deterministically models networks as sets of vertices, which are linked by connections. Such mathematical representation of networks, called graphs are increasingly used in neuroscience to model functional brain networks. It was shown that many forms of structural and functional brain networks have small-world characteristics, thus, constitute networks of dense local and highly effective distal information processing. Motivated by a previous small-world connectivity analysis of resting EEG-data we explored implications of a commonly used analysis approach. This common course of analysis is to compare small-world characteristics between two groups using classical inferential statistics. This however, becomes problematic when using measures of inter-subject correlations, as it is the case in commonly used brain imaging methods such as structural and diffusion tensor imaging with the exception of fibre tracking. Since for each voxel, or region there is only one data point, a measure of connectivity can only be computed for a group. To empirically determine an adequate small-world network threshold and to generate the necessary distribution of measures for classical inferential statistics, samples are generated by thresholding the networks on the group level over a range of thresholds. We believe that there are mainly two problems with this approach. First, the number of thresholded networks is arbitrary. Second, the obtained thresholded networks are not independent samples. Both issues become problematic when using commonly applied parametric statistical tests. Here, we demonstrate potential consequences of the number of thresholds and non-independency of samples in two examples (using artificial data and EEG data. Consequently alternative approaches are presented, which overcome these methodological issues.

  6. Effects of different correlation metrics and preprocessing factors on small-world brain functional networks: a resting-state functional MRI study.

    Directory of Open Access Journals (Sweden)

    Xia Liang

    Full Text Available Graph theoretical analysis of brain networks based on resting-state functional MRI (R-fMRI has attracted a great deal of attention in recent years. These analyses often involve the selection of correlation metrics and specific preprocessing steps. However, the influence of these factors on the topological properties of functional brain networks has not been systematically examined. Here, we investigated the influences of correlation metric choice (Pearson's correlation versus partial correlation, global signal presence (regressed or not and frequency band selection [slow-5 (0.01-0.027 Hz versus slow-4 (0.027-0.073 Hz] on the topological properties of both binary and weighted brain networks derived from them, and we employed test-retest (TRT analyses for further guidance on how to choose the "best" network modeling strategy from the reliability perspective. Our results show significant differences in global network metrics associated with both correlation metrics and global signals. Analysis of nodal degree revealed differing hub distributions for brain networks derived from Pearson's correlation versus partial correlation. TRT analysis revealed that the reliability of both global and local topological properties are modulated by correlation metrics and the global signal, with the highest reliability observed for Pearson's-correlation-based brain networks without global signal removal (WOGR-PEAR. The nodal reliability exhibited a spatially heterogeneous distribution wherein regions in association and limbic/paralimbic cortices showed moderate TRT reliability in Pearson's-correlation-based brain networks. Moreover, we found that there were significant frequency-related differences in topological properties of WOGR-PEAR networks, and brain networks derived in the 0.027-0.073 Hz band exhibited greater reliability than those in the 0.01-0.027 Hz band. Taken together, our results provide direct evidence regarding the influences of correlation metrics

  7. Is the Semantic Web a Small World?

    OpenAIRE

    Bachlechner , Daniel; Strang, Thomas

    2007-01-01

    In this paper, we describe a comprehensive analysis of graph-theoretical properties of online social networks based on the Friend-of-a-Friend (FOAF) ontology. Of particular interest for this work were properties related to the small-world phenomenon. More than 1.6 million of the FOAF documents collected on the Semantic Web met our requirements and were analyzed in depth. Most FOAF documents are created and published by social networking services, blog hosting services, or combinations of the ...

  8. Small world in a seismic network: the California case

    Directory of Open Access Journals (Sweden)

    A. Jiménez

    2008-05-01

    Full Text Available Recent work has shown that disparate systems can be described as complex networks i.e. assemblies of nodes and links with nontrivial topological properties. Examples include technological, biological and social systems. Among them, earthquakes have been studied from this perspective. In the present work, we divide the Southern California region into cells of 0.1°, and calculate the correlation of activity between them to create functional networks for that seismic area, in the same way that the brain activity is studied from the complex network perspective. We found that the network shows small world features.

  9. The small genetic world of Seriatopora hystrix

    Directory of Open Access Journals (Sweden)

    Stuart Kininmonth

    2012-03-01

    Full Text Available The exchange of genetic information among coral reefs, through the transport of larvae, is critical to the function of Australia's Great Barrier Reef because it influences recruitment rates and resilience to disturbance. For many species the genetic composition is not homogeneous and is determined, in part, by the character of the complex dispersal pathways that connect the populations situated on each coral reef. One method of measuring these genetic connections is to examine the microsatellite composition of individual corals and then statistically compare populations across the region. We use these connection strengths, derived from a population similarity measure, to create complex networks to describe and analyse the genetic exchange of the brooding coral, Seriatopora hystrix. The network, based on determining the putative parental origin of individual coral colonies, involved sampling 2163 colonies from 47 collection sites and examining 10 microsatellites. A dispersal network was created from the genetic distance DLR values that measure the genetic similarity of each population (defined by the local sampling effort to every other sampled population based on the microsatellite composition. Graph theory methods show that this network exhibited infrequent long distance links and population clustering which is commonly referred to as small world topology. Comparison with a hydrodynamic based network indicates that the genetic population network topology is similar. This approach shows the genetic structure of the S. hystrix coral follows a small world pattern which supports the results derived from previous hydrodynamic modelling.

  10. Social influence in small-world networks

    Institute of Scientific and Technical Information of China (English)

    孙锴; 毛晓明; 欧阳颀

    2002-01-01

    We report on our numerical studies of the Axelrod model for social influence in small-world networks. Our simulation results show that the topology of thenetwork has a crucial effect on the evolution of cultures. As the randomness of the network increases, the system undergoes a transition from a highly fragmented phase to a uniform phase. We also find that the power-law distribution at the transition point, reported by Castellano et al, is not a critical phenomenon; it exists not only at the onset of transition but also for almost any control parameters. All these power-law distributions are stable against perturbations. A mean-field theory is developed to explain these phenomena.

  11. The Very Special Small World Ceres

    Science.gov (United States)

    Pieters, Carle; Russell, C. T.; Nathues, Andreas; Raymond, Carol; Jaumann, Ralf; De Sanctis, Maria Cristina

    2016-07-01

    The long-lived Dawn spacecraft is now exploring the mysterious dwarf planet Ceres from an orbit only 360 km above the surface. Ceres is the largest planetary body located between Mars and Jupiter and represents a unique transition from rocky bodies of the inner solar system to icy bodies of the outer solar system. The surface, once predicted to be smooth with an ice shell, exhibits abundant craters, several with unfamiliar erosion-like characteristics across ejecta deposits. Although the surface of Ceres is very dark, ray systems around the youngest large craters are extensive, principally seen in high contrast color displays. The uppermost surface is hydrated and shown to contain ammoniated phyllosilicates with a small amount of carbonates but no water ice exposed on the surface (with possibly one exception). The special spectral features diagnostic of Ceres mineralogy are observed globally, but are not found in any meteorite measured in Earth-based laboratories. Unlike Vesta and its HEDs, Ceres has no meteorite sample to guide our understanding of its evolution. Morphologic features found on the surface include a possible (cryo-) volcanic construct, a wide array of tectonic lineaments, smooth deposits of fluidized material associated with several large craters, clusters of pit craters suggesting volatile release, and one remarkable large crater with floor fractures and an array of localized deposits up to 5x brighter than surroundings. Although key data are still being acquired and analyzed to characterize this small hydrated world, Ceres is certain to be a member of the newly recognized category of diverse solar system bodies known as "ocean worlds".

  12. Growing homophilic networks are natural optimal navigable small worlds

    CERN Document Server

    Malkov, Yury A

    2015-01-01

    Navigability, an ability to find a short path between elements using only local information is one of the most fascinating properties of real-life networks. However the exact mechanism responsible for the formation of navigation properties remained unknown. We show that navigability can be achieved by using only two ingredients present in majority of networks: network growth and local homophily, giving the answer why the navigation feature appears in real-life networks. Incremental insertion of metric elements in random order by adding connections to the closest neighbors produces a self-similar optimally wired navigable small world network with an exponential degree distribution. Adding a preferential attachment produces a scale-free network which has shorter greedy paths, but worse (polynomial) scaling of the information extraction locality. Several features of the proposed model are observed in real-life networks, in particular in the brain neural networks, supporting earlier suggestions that they are navi...

  13. A new small-world network created by Cellular Automata

    Science.gov (United States)

    Ruan, Yuhong; Li, Anwei

    2016-08-01

    In this paper, we generate small-world networks by the Cellular Automaton based on starting with one-dimensional regular networks. Besides the common properties of small-world networks with small average shortest path length and large clustering coefficient, the small-world networks generated in this way have other properties: (i) The edges which are cut in the regular network can be controlled that whether the edges are reconnected or not, and (ii) the number of the edges of the small-world network model equals the number of the edges of the original regular network. In other words, the average degree of the small-world network model equals to the average degree of the original regular network.

  14. The developing brain in a multitasking world

    OpenAIRE

    Rothbart, Mary K.; Michael I. Posner

    2015-01-01

    To understand the problem of multitasking, it is necessary to examine the brain’s attention networks that underlie the ability to switch attention between stimuli and tasks and to maintain a single focus among distractors. In this paper we discuss the development of brain networks related to the functions of achieving the alert state, orienting to sensory events, and developing self-control. These brain networks are common to everyone, but their efficiency varies among individuals and reflect...

  15. Using probabilistic cache scheme to construct the small world network

    Institute of Scientific and Technical Information of China (English)

    ZOU Fu-tai; YI Ping; MA Fan-yuan; LI Jian-hua

    2007-01-01

    Recently some P2P systems have constructed the small world network using the small world model so as to improve the routing performance. In this paper, we propose a novel probabilistic cache scheme to construct the small world network based on the small world model and use it to improve CAN, that is, PCCAN ( Probabilistic Cache - based CAN). PCCAN caches the long contact. It uses the worm routing replacing mechanism and probabilistic replacing strategy on the cache. The probabilistic cache scheme proves to be an efficient approach to model the small world phenomenon. Experiments in both the static and the dynamic network show that PCCAN can converge to the steady state with the cache scheme, and the routing performance is significantly improved with additional low overheads in the network compared with CAN.

  16. The developing brain in a multitasking world.

    Science.gov (United States)

    Rothbart, Mary K; Posner, Michael I

    2015-03-01

    To understand the problem of multitasking, it is necessary to examine the brain's attention networks that underlie the ability to switch attention between stimuli and tasks and to maintain a single focus among distractors. In this paper we discuss the development of brain networks related to the functions of achieving the alert state, orienting to sensory events, and developing self-control. These brain networks are common to everyone, but their efficiency varies among individuals and reflects both genes and experience. Training can alter brain networks. We consider two forms of training: (1) practice in tasks that involve particular networks, and (2) changes in brain state through such practices as meditation that may influence many networks. Playing action video games and multitasking are themselves methods of training the brain that can lead to improved performance but also to overdependence on media activity. We consider both of these outcomes and ideas about how to resist overdependence on media. Overall, our paper seeks to inform the reader about what has been learned about attention that can influence multitasking over the course of development.

  17. Brain Functional Analysis of Photon-Stimulation Functional Magnetic Resonance Imaging Based on Small-World Networks%脑功能激活光诱发机理小世界网络分析研究

    Institute of Scientific and Technical Information of China (English)

    丁尚文; 钱志余; 李韪韬; 陶玲; 胡光霞

    2012-01-01

    Differences of information transmission network hub. network aggregation and minimum path of information transmission under the states of photon stimulation and resting are studied- The brain functional network is constructed based on the small-world network theory. By analyzing the network connectivity of brain function, cluster coefficient and the minimum path, the conclusion is drawn that stronger functional areas of information transferring are the insula and the posterior cingulate state. Thalamus and hippocampus have a greater aggregation. The information amount of photon stimulation from superior frontal gyrus to the middle occipital gyrus is passed through middle temporal gyrus under the photon stimulation. Those are drawn under rest state that stronger functional areas of information transferring are the cuneus and the lingual gyrus, the central lobule and superior temporal gyrus have a greater aggregations the information amount of photon stimulation from left superior frontal gyrus to left the middle occipital gyrus is passed through middle temporal gyrus, cuneus and that from right superior frontal gyrus to right the middle occipital gyrus is passed through anterior cingulate gyrus and inferior occipital gyrus.%研究光诱发和静息两种状态下的脑功能网络的信息传输枢纽、网络聚合能力和信息传输的最小路径的差异性.采用小世界网络理论对脑功能网络进行建模,通过对脑功能网络连接度、簇系数和最小路径进行分析,得出光诱发状态下的信息传输重要枢纽为岛叶、后扣带回功能区;丘脑、海马两处功能网络有较大聚合能力.光诱发过程从额上回经颞中回传输到枕中回.静息状态下的信息传输重要枢纽为楔叶、舌回;中央旁小叶、颞上回脑功能网络有较大聚合能力.静息状态下的左半区最佳信息传输路径为左额上回、左颞中回、右楔叶最后到左枕中回;右脑半区

  18. Adaptive Synchronization in Small-World Dynamical Networks

    Institute of Scientific and Technical Information of China (English)

    ZOU Yan-li; ZHU Jie; LUO Xiao-shu

    2007-01-01

    Adaptive synchronization in NW small-world dynamical networks was studied. Firstly, an adaptive synchronization method is presented and explained. Then, it is applied to two different classes of dynamical networks,one is a class-B network, small-world connected R(o)ssler oscillators, the other is a class-A network, small-world connected Chua's circuits. The simulation verifies the validity of the presented method. It also shows that the adaptive synchronization method is robust to the variations of the node systems parameters. So the presented method can be used in networks whose node systems have unknown or time-varying parameters.

  19. Small-world network spectra in mean-field theory.

    Science.gov (United States)

    Grabow, Carsten; Grosskinsky, Stefan; Timme, Marc

    2012-05-25

    Collective dynamics on small-world networks emerge in a broad range of systems with their spectra characterizing fundamental asymptotic features. Here we derive analytic mean-field predictions for the spectra of small-world models that systematically interpolate between regular and random topologies by varying their randomness. These theoretical predictions agree well with the actual spectra (obtained by numerical diagonalization) for undirected and directed networks and from fully regular to strongly random topologies. These results may provide analytical insights to empirically found features of dynamics on small-world networks from various research fields, including biology, physics, engineering, and social science.

  20. Geometric Assortative Growth Model for Small-World Networks

    Directory of Open Access Journals (Sweden)

    Yilun Shang

    2014-01-01

    Full Text Available It has been shown that both humanly constructed and natural networks are often characterized by small-world phenomenon and assortative mixing. In this paper, we propose a geometrically growing model for small-world networks. The model displays both tunable small-world phenomenon and tunable assortativity. We obtain analytical solutions of relevant topological properties such as order, size, degree distribution, degree correlation, clustering, transitivity, and diameter. It is also worth noting that the model can be viewed as a generalization for an iterative construction of Farey graphs.

  1. Phase Synchronization in Small World Chaotic Neural Networks

    Institute of Scientific and Technical Information of China (English)

    WANG Qing-Yun; LU Qi-Shao

    2005-01-01

    @@ To understand collective motion of realneural networks very well, we investigate collective phase synchronization of small world chaotic Hindmarsh-Rose (HR) neural networks. By numerical simulations, we conclude that small world chaotic HR neural networks can achieve collective phase synchronization. Furthermore, it is shown that phase synchronization of small world chaotic HR neural networks is dependent on the coupling strength,the connection topology (which is determined by the probability p), as well as the coupling number. These phenomena are important to guide us to understand the synchronization of real neural networks.

  2. Algebraic approach to small-world network models

    Science.gov (United States)

    Rudolph-Lilith, Michelle; Muller, Lyle E.

    2014-01-01

    We introduce an analytic model for directed Watts-Strogatz small-world graphs and deduce an algebraic expression of its defining adjacency matrix. The latter is then used to calculate the small-world digraph's asymmetry index and clustering coefficient in an analytically exact fashion, valid nonasymptotically for all graph sizes. The proposed approach is general and can be applied to all algebraically well-defined graph-theoretical measures, thus allowing for an analytical investigation of finite-size small-world graphs.

  3. Geometric assortative growth model for small-world networks.

    Science.gov (United States)

    Shang, Yilun

    2014-01-01

    It has been shown that both humanly constructed and natural networks are often characterized by small-world phenomenon and assortative mixing. In this paper, we propose a geometrically growing model for small-world networks. The model displays both tunable small-world phenomenon and tunable assortativity. We obtain analytical solutions of relevant topological properties such as order, size, degree distribution, degree correlation, clustering, transitivity, and diameter. It is also worth noting that the model can be viewed as a generalization for an iterative construction of Farey graphs.

  4. Calling Gaia: World Brains and Global Memory

    NARCIS (Netherlands)

    S. Besser

    2016-01-01

    ‘See the world we come from. There is no green there. They killed their mother. And they are gonna do the same here’. This is earthling Jake Sully speaking to Eywa, the Gaia-like goddess and balancing force of the ecosystem of the planetoid Pandora. At a dramatic narrative juncture of the film Avata

  5. The World Largest Small Satellite R&D Center Completed

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    The National Institute of Small Satellite Research and Applications, constructed by Dongfanghong Satellite Company,was completed on December 14,2004. It is the world largest satellite research and development center.

  6. Dawn of small worlds dwarf planets, asteroids, comets

    CERN Document Server

    Moltenbrey, Michael

    2016-01-01

    This book gives a detailed introduction to the thousands and thousands of smaller bodies in the solar system. Written for interested laymen, amateur astronomers and students it describes the nature and origin of asteroids, dwarf planets and comets, and gives detailed information about their role in the solar system. The author nicely reviews the history of small-world-exploration and describes past, current and future space craft missions studying small worlds, and presents their results. Readers will learn that small solar system worlds have a dramatically different nature and appearance than the planets. Even though research activity on small worlds has increased in the recent past many of their properties are still in the dark and need further research.

  7. Growing Homophilic Networks Are Natural Navigable Small Worlds.

    Directory of Open Access Journals (Sweden)

    Yury A Malkov

    Full Text Available Navigability, an ability to find a logarithmically short path between elements using only local information, is one of the most fascinating properties of real-life networks. However, the exact mechanism responsible for the formation of navigation properties remained unknown. We show that navigability can be achieved by using only two ingredients present in the majority of networks: network growth and local homophily, giving a persuasive answer how the navigation appears in real-life networks. A very simple algorithm produces hierarchical self-similar optimally wired navigable small world networks with exponential degree distribution by using only local information. Adding preferential attachment produces a scale-free network which has shorter greedy paths, but worse (power law scaling of the information extraction locality (algorithmic complexity of a search. Introducing saturation of the preferential attachment leads to truncated scale-free degree distribution that offers a good tradeoff between these parameters and can be useful for practical applications. Several features of the model are observed in real-life networks, in particular in the brain neural networks, supporting the earlier suggestions that they are navigable.

  8. Growing Homophilic Networks Are Natural Navigable Small Worlds.

    Science.gov (United States)

    Malkov, Yury A; Ponomarenko, Alexander

    2016-01-01

    Navigability, an ability to find a logarithmically short path between elements using only local information, is one of the most fascinating properties of real-life networks. However, the exact mechanism responsible for the formation of navigation properties remained unknown. We show that navigability can be achieved by using only two ingredients present in the majority of networks: network growth and local homophily, giving a persuasive answer how the navigation appears in real-life networks. A very simple algorithm produces hierarchical self-similar optimally wired navigable small world networks with exponential degree distribution by using only local information. Adding preferential attachment produces a scale-free network which has shorter greedy paths, but worse (power law) scaling of the information extraction locality (algorithmic complexity of a search). Introducing saturation of the preferential attachment leads to truncated scale-free degree distribution that offers a good tradeoff between these parameters and can be useful for practical applications. Several features of the model are observed in real-life networks, in particular in the brain neural networks, supporting the earlier suggestions that they are navigable.

  9. Influence of choice of null network on small-world parameters of structural correlation networks.

    Science.gov (United States)

    Hosseini, S M Hadi; Kesler, Shelli R

    2013-01-01

    In recent years, coordinated variations in brain morphology (e.g., volume, thickness) have been employed as a measure of structural association between brain regions to infer large-scale structural correlation networks. Recent evidence suggests that brain networks constructed in this manner are inherently more clustered than random networks of the same size and degree. Thus, null networks constructed by randomizing topology are not a good choice for benchmarking small-world parameters of these networks. In the present report, we investigated the influence of choice of null networks on small-world parameters of gray matter correlation networks in healthy individuals and survivors of acute lymphoblastic leukemia. Three types of null networks were studied: 1) networks constructed by topology randomization (TOP), 2) networks matched to the distributional properties of the observed covariance matrix (HQS), and 3) networks generated from correlation of randomized input data (COR). The results revealed that the choice of null network not only influences the estimated small-world parameters, it also influences the results of between-group differences in small-world parameters. In addition, at higher network densities, the choice of null network influences the direction of group differences in network measures. Our data suggest that the choice of null network is quite crucial for interpretation of group differences in small-world parameters of structural correlation networks. We argue that none of the available null models is perfect for estimation of small-world parameters for correlation networks and the relative strengths and weaknesses of the selected model should be carefully considered with respect to obtained network measures.

  10. Small-World Characteristics of Cortical Connectivity Changes in Acute Stroke.

    Science.gov (United States)

    Caliandro, Pietro; Vecchio, Fabrizio; Miraglia, Francesca; Reale, Giuseppe; Della Marca, Giacomo; La Torre, Giuseppe; Lacidogna, Giordano; Iacovelli, Chiara; Padua, Luca; Bramanti, Placido; Rossini, Paolo Maria

    2017-01-01

    Background After cerebral ischemia, disruption and subsequent reorganization of functional connections occur both locally and remote to the lesion. Recently, complexity of brain connectivity has been described using graph theory, a mathematical approach that depicts important properties of complex systems by quantifying topologies of network representations. Functional and dynamic changes of brain connectivity can be reliably analyzed via electroencephalography (EEG) recordings even when they are not yet reflected in structural changes of connections. Objective We tested whether and how ischemic stroke in the acute stage may determine changes in small-worldness of cortical networks as measured by cortical sources of EEG. Methods Graph characteristics of EEG of 30 consecutive stroke patients in acute stage (no more than 5 days after the event) were examined. Connectivity analysis was performed using eLORETA in both hemispheres. Results Network rearrangements were mainly detected in delta, theta, and alpha bands when patients were compared with healthy subjects. In delta and alpha bands similar findings were observed in both hemispheres regardless of the side of ischemic lesion: bilaterally decreased small-worldness in the delta band and bilaterally increased small-worldness in the alpha2 band. In the theta band, bilaterally decreased small-worldness was observed only in patients with stroke in the left hemisphere. Conclusions After an acute stroke, brain cortex rearranges its network connections diffusely, in a frequency-dependent modality probably in order to face the new anatomical and functional frame.

  11. Complex Behavior in a Selective Aging Neuron Model Based on Small World Networks

    Institute of Scientific and Technical Information of China (English)

    LUO Min-Jie; ZHANG Gui-Qing; LIU Qiu-Yu; CHEN Tian-Lun

    2008-01-01

    Complex behavior in a selective aging simple neuron model based on small world networks is investigated. The basic elements of the model are endowed with the main features of a neuron function. The structure of the selective aging neuron model is discussed. We also give some properties of the new network and find that the neuron model displays a power-law behavior. If the brain network is small world-like network, the mean avalanche size is almost the same unless the aging parameter is big enough.

  12. Collective Relaxation Dynamics of Small-World Networks

    CERN Document Server

    Grabow, Carsten; Kurths, Jürgen; Timme, Marc

    2015-01-01

    Complex networks exhibit a wide range of collective dynamic phenomena, including synchronization, diffusion, relaxation, and coordination processes. Their asymptotic dynamics is generically characterized by the local Jacobian, graph Laplacian or a similar linear operator. The structure of networks with regular, small-world and random connectivities are reasonably well understood, but their collective dynamical properties remain largely unknown. Here we present a two-stage mean-field theory to derive analytic expressions for network spectra. A single formula covers the spectrum from regular via small-world to strongly randomized topologies in Watts-Strogatz networks, explaining the simultaneous dependencies on network size N, average degree k and topological randomness q. We present simplified analytic predictions for the second largest and smallest eigenvalue, and numerical checks confirm our theoretical predictions for zero, small and moderate topological randomness q, including the entire small-world regime...

  13. Impaired small-world network efficiency and dynamic functional distribution in patients with cirrhosis.

    Directory of Open Access Journals (Sweden)

    Tun-Wei Hsu

    Full Text Available Hepatic encephalopathy (HE is a complex neuropsychiatric syndrome and a major complication of liver cirrhosis. Dysmetabolism of the brain, related to elevated ammonia levels, interferes with intercortical connectivity and cognitive function. For evaluation of network efficiency, a 'small-world' network model can quantify the effectiveness of information transfer within brain networks. This study aimed to use small-world topology to investigate abnormalities of neuronal connectivity among widely distributed brain regions in patients with liver cirrhosis using resting-state functional magnetic resonance imaging (rs-fMRI. Seventeen cirrhotic patients without HE, 9 with minimal HE, 9 with overt HE, and 35 healthy controls were compared. The interregional correlation matrix was obtained by averaging the rs-fMRI time series over all voxels in each of the 90 regions using the automated anatomical labeling model. Cost and correlation threshold values were then applied to construct the functional brain network. The absolute and relative network efficiencies were calculated; quantifying distinct aspects of the local and global topological network organization. Correlations between network topology parameters, ammonia levels, and the severity of HE were determined using linear regression and ANOVA. The local and global topological efficiencies of the functional connectivity network were significantly disrupted in HE patients; showing abnormal small-world properties. Alterations in regional characteristics, including nodal efficiency and nodal strength, occurred predominantly in the association, primary, and limbic/paralimbic regions. The degree of network organization disruption depended on the severity of HE. Ammonia levels were also significantly associated with the alterations in local network properties. Results indicated that alterations in the rs-fMRI network topology of the brain were associated with HE grade; and that focal or diffuse lesions

  14. Navigating a 2D Virtual World using Direct Brain Stimulation

    Directory of Open Access Journals (Sweden)

    Darby M. Losey

    2016-11-01

    Full Text Available Can the human brain learn to interpret inputs from a virtual world delivered directly through brain stimulation? We answer this question by describing the first demonstration of humans playing a computer game utilizing only direct brain stimulation and no other sensory inputs. The demonstration also provides the first instance of artificial sensory information, in this case depth, being delivered directly to the human brain through noninvasive methods. Our approach utilizes transcranial magnetic stimulation (TMS of the human visual cortex to convey binary information about obstacles in a virtual maze. At certain intensities, TMS elicits visual percepts known as phosphenes, which transmits information to the subject about their current location within the maze. Using this computer-brain interface (CBI, five subjects successfully navigated an average of 92% of all the steps in a variety of virtual maze worlds. They also became more accurate in solving the task over time. These results suggest that humans can learn to utilize information delivered directly and noninvasively to their brains to solve tasks that cannot be solved using their natural senses, opening the door to human sensory augmentation and novel modes of human-computer interaction.

  15. Brain size and ecology in small mammals and primates.

    OpenAIRE

    1980-01-01

    Comparisons of brain-body size relationships within small mammal and primate families reveal intergeneric differences related to diet and foraging strategy. These same associations between relative brain size and ecology are also evident among interfamily comparisons.

  16. Cascading failures of interdependent modular small-world networks

    Science.gov (United States)

    Zhu, Guowei; Wang, Xianpei; Tian, Meng; Dai, Dangdang; Long, Jiachuan; Zhang, Qilin

    2016-07-01

    Much empirical evidence shows that many real-world networks fall into the broad class of small-world networks and have a modular structure. The modularity has been revealed to have an important effect on cascading failure in isolated networks. However, the corresponding results for interdependent modular small-world networks remain missing. In this paper, we investigate the relationship between cascading failures and the intra-modular rewiring probabilities and inter-modular connections under different coupling preferences, i.e. random coupling with modules (RCWM), assortative coupling in modules (ACIM) and assortative coupling with modules (ACWM). The size of the largest connected component is used to evaluate the robustness from global and local perspectives. Numerical results indicate that increasing intra-modular rewiring probabilities and inter-modular connections can improve the robustness of interdependent modular small-world networks under intra-attacks and inter-attacks. Meanwhile, experiments on three coupling strategies demonstrate that ACIM has a better effect on preventing the cascading failures compared with RCWM and ACWM. These results can be helpful to allocate and optimize the topological structure of interdependent modular small-world networks to improve the robustness of such networks.

  17. Interface motion and pinning in small-world networks.

    Science.gov (United States)

    Boyer, Denis; Miramontes, Octavio

    2003-03-01

    We show that the nonequilibrium dynamics of systems with many interacting elements located on a small-world network can be much slower than on regular networks. As an example, we study the phase ordering dynamics of the Ising model on a Watts-Strogatz network, after a quench in the ferromagnetic phase at zero temperature. In one and two dimensions, small-world features produce dynamically frozen configurations, disordered at large length scales, analogous to random field models. This picture differs from the common knowledge (supported by equilibrium results) that ferromagnetic shortcut connections favor order and uniformity. We briefly discuss some implications of these results regarding the dynamics of social changes.

  18. Deterministic multidimensional growth model for small-world networks

    CERN Document Server

    Peng, Aoyuan

    2011-01-01

    We proposed a deterministic multidimensional growth model for small-world networks. The model can characterize the distinguishing properties of many real-life networks with geometric space structure. Our results show the model possesses small-world effect: larger clustering coefficient and smaller characteristic path length. We also obtain some accurate results for its properties including degree distribution, clustering coefficient and network diameter and discuss them. It is also worth noting that we get an accurate analytical expression for calculating the characteristic path length. We verify numerically and experimentally these main features.

  19. Small Worlds Week: Raising Curiosity and Contributing to STEM

    Science.gov (United States)

    Ng, C.; Mayo, L.; Stephenson, B. E.; Keck, A.; Cline, T. D.; Lewis, E. M.

    2015-12-01

    Dwarf planets, comets, asteroids, and icy moons took center stage in the years 2014-2015 as multiple spacecraft (New Horizons, Dawn, Rosetta, Cassini) and ground-based observing campaigns observed these small and yet amazing celestial bodies. Just prior to the historic New Horizons encounter with the Pluto system, NASA celebrated Small Worlds Week (July 6-10) as a fully online program to highlight small worlds mission discoveries. Small Worlds Week leveraged the infrastructure of Sun-Earth Days that included a robust web design, exemplary education materials, hands-on fun activities, multimedia resources, science and career highlights, and a culminating event. Each day from July 6-9, a new class of solar system small worlds was featured on the website: Monday-comets, Tuesday-asteroids, Wednesday-icy moons, and Thursday-dwarf planets. Then on Friday, July 10, nine scientists from Goddard Space Flight Center, Jet Propulsion Laboratory, Naval Research Laboratory, and Lunar and Planetary Institute gathered online for four hours to answer questions from the public via Facebook and Twitter. Throughout the afternoon the scientists worked closely with a social media expert and several summer interns to reply to inquirers and to archive their chats. By all accounts, Small Worlds Week was a huge success. The group plans to improve and replicate the program during the school year with a more classroom focus, and then to build and extend the program to be held every year. For more information, visit http:// sunearthday.nasa.gov or catch us on Twitter, #nasasww.

  20. Hodge Decomposition of Information Flow on Small-World Networks

    Science.gov (United States)

    Haruna, Taichi; Fujiki, Yuuya

    2016-01-01

    We investigate the influence of the small-world topology on the composition of information flow on networks. By appealing to the combinatorial Hodge theory, we decompose information flow generated by random threshold networks on the Watts-Strogatz model into three components: gradient, harmonic and curl flows. The harmonic and curl flows represent globally circular and locally circular components, respectively. The Watts-Strogatz model bridges the two extreme network topologies, a lattice network and a random network, by a single parameter that is the probability of random rewiring. The small-world topology is realized within a certain range between them. By numerical simulation we found that as networks become more random the ratio of harmonic flow to the total magnitude of information flow increases whereas the ratio of curl flow decreases. Furthermore, both quantities are significantly enhanced from the level when only network structure is considered for the network close to a random network and a lattice network, respectively. Finally, the sum of these two ratios takes its maximum value within the small-world region. These findings suggest that the dynamical information counterpart of global integration and that of local segregation are the harmonic flow and the curl flow, respectively, and that a part of the small-world region is dominated by internal circulation of information flow. PMID:27733817

  1. Tutte polynomial of a small-world Farey graph

    Science.gov (United States)

    Liao, Yunhua; Hou, Yaoping; Shen, Xiaoling

    2013-11-01

    In this paper, we find recursive formulas for the Tutte polynomials of a family of small-world Farey graphs, which are modular, and has an exponential degree hierarchy. As applications of the recursive formula, the exact expressions for the chromatic polynomial and the reliability polynomial of Fare graphs are derived and the number of connected spanning subgraphs is also obtained.

  2. Optimal Routing in a Small-World Network

    Institute of Scientific and Technical Information of China (English)

    Jian-Yang Zeng; Wen-Jing Hsu

    2006-01-01

    Substantial research has been devoted to the modelling of the small-world phenomenon that arises in nature as well as human society. Earlier work has focused on the static properties of various small-world models. To examine the routing aspects, Kleinberg proposes a model based on a d-dimensional toroidal lattice with long-range links chosen at random according to the d-harmonic distribution. Kleinberg shows that, by using only local information, the greedy routing algorithm performs in O(lg2 n) expected number of hops. We extend Kleinberg's small-world model by allowing each node x to have two more random links to nodes chosen uniformly and randomly within (lg n)-d Manhattan distance from x. Basedon this extended model, we then propose an oblivious algorithm that can route messages between any two nodes in O(lg n)expected number of hops. Our routing algorithm keeps only O((lg n)β+1) bits of information on each node, where 1 <β< 2,thus being scalable w.r.t. the network size. To our knowledge, our result is the first to achieve the optimal routing complexity while still keeping a poly-logarithmic number of bits of information stored on each node in the small-world networks.

  3. The emerging world of small silencing RNAs in protozoan parasites.

    Science.gov (United States)

    Atayde, Vanessa D; Tschudi, Christian; Ullu, Elisabetta

    2011-07-01

    A new RNA world has emerged in the past 10 years with the discovery of a plethora of 20- to 30-nucleotide long small RNAs that are involved in various gene silencing mechanisms. These small RNAs have considerably changed our view of the regulation of gene expression in eukaryotic organisms, with a major shift towards epigenetic and post-transcriptional mechanisms. In this article, we focus on the striking diversity of small silencing RNAs that have been identified in several protozoan parasites and their potential biological role.

  4. Disturbed small-world networks and neurocognitive function in frontal lobe low-grade glioma patients.

    Directory of Open Access Journals (Sweden)

    Qingling Huang

    Full Text Available BACKGROUND: Brain tumor patients often associated with losses of the small-world configuration and neurocognitive functions before operations. However, few studies were performed on the impairments of frontal lobe low-grade gliomas (LGG after tumor resection using small-world network features. METHODOLOGY/PRINCIPAL FINDINGS: To detect differences in the whole brain topology among LGG patients before and after operation, a combined study of neurocognitive assessment and graph theoretical network analysis of fMRI data was performed. We collected resting-state fMRI data of 12 carefully selected frontal lobe LGG patients before and after operation. We calculated the topological properties of brain functional networks in the 12 LGG, and compared with 12 healthy controls (HCs. We also applied Montreal Cognitive Assessment (MoCA in a subset of patients (n = 12, including before and after operation groups and HCs (n = 12. The resulting functional connectivity matrices were constructed for all 12 patients, and binary network analysis was performed. In the range of 0.05 ≤ Kcos t ≤ 0.35, the functional networks in preoperative LGG and postoperative one both fitted the definition of small-worldness. We proposed Knet = 0.20 as small-world network interval, and the results showed that the topological properties were found to be disrupted in the two LGG groups, meanwhile the global efficiency increased and the local efficiency decreased. Lnet in the two LGG groups both were longer than HCs. Cnet in the LGG groups were smaller than HCs. Compared with the Hcs, MoCA in the two LGG groups were lower than HCs with significant difference, and the disturbed networks in the LGG were negatively related to worse MoCA scores. CONCLUSIONS: Disturbed small-worldness preperty in the two LGG groups was found and widely spread in the strength and spatial organization of brain networks, and the alterated small-world network may be responsible for cognitive

  5. Small Worlds in the Tree Topologies of Wireless Sensor Networks

    DEFF Research Database (Denmark)

    Qiao, Li; Lingguo, Cui; Baihai, Zhang

    2010-01-01

    In this study, the characteristics of small worlds are investigated in the context of the tree topologies of wireless sensor networks. Tree topologies, which construct spatial graphs with larger characteristic path lengths than random graphs and small clustering coefficients, are ubiquitous...... in wireless sensor networks. Suffering from the link rewiring or the link addition, the characteristic path length of the tree topology reduces rapidly and the clustering coefficient increases greatly. The variety of characteristic path length influences the time synchronization characteristics of wireless...... sensor networks greatly. With the increase of the link rewiring or the link addition probability, the time synchronization error decreases drastically. Two novel protocols named LEACH-SW and TREEPSI-SW are proposed to improve the performances of the sensor networks, in which the small world...

  6. Cerebral complexity preceded enlarged brain size and reduced olfactory bulbs in Old World monkeys

    OpenAIRE

    Gonzales, L.; Benefit, B.; McCrossin, M.; Spoor, F.

    2015-01-01

    Analysis of the only complete early cercopithecoid (Old World monkey) endocast currently known, that of 15-million-year (Myr)-old Victoriapithecus, reveals an unexpectedly small endocranial volume (ECV) relative to body size and a large olfactory bulb volume relative to ECV, similar to extant lemurs and Oligocene anthropoids. However, the Victoriapithecus brain has principal and arcuate sulci of the frontal lobe not seen in the stem catarrhine Aegyptopithecus, as well as a distinctive cercopi...

  7. A small world model for the spread of HIV infection

    Directory of Open Access Journals (Sweden)

    Israel T. Vieira

    2011-08-01

    Full Text Available It has long been recognised that the structure of social networks plays an important role in the dynamics of disease propagation. The spread of HIV usually results from a complex network of social interactions and other factors related to culture, sexual behaviour, demography, geography and disease characteristics, as well as the availability, accessibility and delivery of healthcare. The small world phenomenon has been used for representing social network interactions. It states that, given some random connections, the degrees of separation between any two individuals within a population can be very small. In this paper we present a discrete event simulation model which uses a variant of the small world network model to represent social interactions and the sexual transmission of HIV within a population. We use the model to demonstrate the importance of the choice of topology and initial distribution of infection, and capture the direct and non-linear relationship between the probability of a casual partnership (small world randomness parameter and the spread of HIV.

  8. Exploring the Critical Sensitivity in Small-World Networks

    Institute of Scientific and Technical Information of China (English)

    罗嘉元; 欧阳颀

    2004-01-01

    Catastrophic phenomena such as earthquakes, avalanches, and critical points in the stock market are hard to predict. Recently, Xia et al. [Pure Appl. Geophys. 159 (2002)2491] showed that a geometrical system near catastrophic rupture presents a general critical sensitivity: the system becomes significantly sensitive near the catastrophe transition. Here we report that the phenomenon of critical sensitivity also exists in small-world network systems. With the increase of the small-world rewiring probability p, from the regular network p = 0 to the random one p = 1, the system performs more sensitively before the critical point while remaining in better organization through the evolutional progress, and the prediction threshold Ps performs more in advance. The concept of critical sensitivity can be applied to other complex network systems.

  9. Can recurrence networks show small-world property?

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, Rinku, E-mail: rinku.jacob.vallanat@gmail.com [Department of Physics, The Cochin College, Cochin, 682002 (India); Harikrishnan, K.P., E-mail: kp_hk2002@yahoo.co.in [Department of Physics, The Cochin College, Cochin, 682002 (India); Misra, R., E-mail: rmisra@iucaa.in [Inter University Centre for Astronomy and Astrophysics, Pune, 411007 (India); Ambika, G., E-mail: g.ambika@iiserpune.ac.in [Indian Institute of Science Education and Research, Pune, 411008 (India)

    2016-08-12

    Recurrence networks are complex networks, constructed from time series data, having several practical applications. Though their properties when constructed with the threshold value ϵ chosen at or just above the percolation threshold of the network are quite well understood, what happens as the threshold increases beyond the usual operational window is still not clear from a complex network perspective. The present Letter is focused mainly on the network properties at intermediate-to-large values of the recurrence threshold, for which no systematic study has been performed so far. We argue, with numerical support, that recurrence networks constructed from chaotic attractors with ϵ equal to the usual recurrence threshold or slightly above cannot, in general, show small-world property. However, if the threshold is further increased, the recurrence network topology initially changes to a small-world structure and finally to that of a classical random graph as the threshold approaches the size of the strange attractor. - Highlights: • Properties of recurrence networks at intermediate-to-large values of recurrence threshold are analyzed from a complex network perspective. • Using a combined plot of characteristic path length and clustering coefficient, it is shown that the recurrence network constructed with recurrence threshold equal to or just above the percolation threshold cannot, in general, display small-world property. • As the recurrence threshold is increased from its usual operational window, the resulting network makes a smooth transition initially to a small-world network for an intermediate range of thresholds and finally to the classical random graph as the threshold becomes comparable to the size of the attractor.

  10. Yet another approach to the small world phenomenon

    CERN Document Server

    Medo, M

    2006-01-01

    We introduce a metrics to the random network of the human relationships. Obtained spatial graph allows us to calculate the average separation of people in a very simple manner. Acquired results agree with the well-known presence of the small-world phenomenon in human relationships. It indicates that this feature can be understood merely as the consequence of the probability composition. We will also examine how this phenomenon evolves with the development of the human society.

  11. Scaling and percolation in the small-world network model

    Energy Technology Data Exchange (ETDEWEB)

    Newman, M. E. J. [Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501 (United States); Watts, D. J. [Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501 (United States)

    1999-12-01

    In this paper we study the small-world network model of Watts and Strogatz, which mimics some aspects of the structure of networks of social interactions. We argue that there is one nontrivial length-scale in the model, analogous to the correlation length in other systems, which is well-defined in the limit of infinite system size and which diverges continuously as the randomness in the network tends to zero, giving a normal critical point in this limit. This length-scale governs the crossover from large- to small-world behavior in the model, as well as the number of vertices in a neighborhood of given radius on the network. We derive the value of the single critical exponent controlling behavior in the critical region and the finite size scaling form for the average vertex-vertex distance on the network, and, using series expansion and Pade approximants, find an approximate analytic form for the scaling function. We calculate the effective dimension of small-world graphs and show that this dimension varies as a function of the length-scale on which it is measured, in a manner reminiscent of multifractals. We also study the problem of site percolation on small-world networks as a simple model of disease propagation, and derive an approximate expression for the percolation probability at which a giant component of connected vertices first forms (in epidemiological terms, the point at which an epidemic occurs). The typical cluster radius satisfies the expected finite size scaling form with a cluster size exponent close to that for a random graph. All our analytic results are confirmed by extensive numerical simulations of the model. (c) 1999 The American Physical Society.

  12. Bifurcations and chaos control in discrete small-world networks

    Institute of Scientific and Technical Information of China (English)

    Li Ning; Sun Hai-Yi; Zhang Qing-Ling

    2012-01-01

    An impulsive delayed feedback control strategy to control period-doubling bifurcations and chaos is proposed.The control method is then applied to a discrete small-world network model.Qualitative analyses and simulations show that under a generic condition,the bifurcations and the chaos can be delayed or eliminated completely.In addition,the periodic orbits embedded in the chaotic attractor can be stabilized.

  13. A small-world network model of facial emotion recognition.

    Science.gov (United States)

    Takehara, Takuma; Ochiai, Fumio; Suzuki, Naoto

    2016-01-01

    Various models have been proposed to increase understanding of the cognitive basis of facial emotions. Despite those efforts, interactions between facial emotions have received minimal attention. If collective behaviours relating to each facial emotion in the comprehensive cognitive system could be assumed, specific facial emotion relationship patterns might emerge. In this study, we demonstrate that the frameworks of complex networks can effectively capture those patterns. We generate 81 facial emotion images (6 prototypes and 75 morphs) and then ask participants to rate degrees of similarity in 3240 facial emotion pairs in a paired comparison task. A facial emotion network constructed on the basis of similarity clearly forms a small-world network, which features an extremely short average network distance and close connectivity. Further, even if two facial emotions have opposing valences, they are connected within only two steps. In addition, we show that intermediary morphs are crucial for maintaining full network integration, whereas prototypes are not at all important. These results suggest the existence of collective behaviours in the cognitive systems of facial emotions and also describe why people can efficiently recognize facial emotions in terms of information transmission and propagation. For comparison, we construct three simulated networks--one based on the categorical model, one based on the dimensional model, and one random network. The results reveal that small-world connectivity in facial emotion networks is apparently different from those networks, suggesting that a small-world network is the most suitable model for capturing the cognitive basis of facial emotions.

  14. Fast and robust image segmentation by small-world neural oscillator networks.

    Science.gov (United States)

    Li, Chunguang; Li, Yuke

    2011-06-01

    Inspired by the temporal correlation theory of brain functions, researchers have presented a number of neural oscillator networks to implement visual scene segmentation problems. Recently, it is shown that many biological neural networks are typical small-world networks. In this paper, we propose and investigate two small-world models derived from the well-known LEGION (locally excitatory and globally inhibitory oscillator network) model. To form a small-world network, we add a proper proportion of unidirectional shortcuts (random long-range connections) to the original LEGION model. With local connections and shortcuts, the neural oscillators can not only communicate with neighbors but also exchange phase information with remote partners. Model 1 introduces excitatory shortcuts to enhance the synchronization within an oscillator group representing the same object. Model 2 goes further to replace the global inhibitor with a sparse set of inhibitory shortcuts. Simulation results indicate that the proposed small-world models could achieve synchronization faster than the original LEGION model and are more likely to bind disconnected image regions belonging together. In addition, we argue that these two models are more biologically plausible.

  15. Extraction of network topology from multi-electrode recordings: Is there a small-world effect?

    Directory of Open Access Journals (Sweden)

    Felipe eGerhard

    2011-02-01

    Full Text Available The simultaneous recording of the activity of many neurons poses challenges for multivariate data analysis. Here, we propose a general scheme of reconstruction of the functional network from spike train recordings. Effective, causal interactions are estimated by fitting Generalized Linear Models (GLMs on the neural responses, incorporating effects of the neurons' self-history, of input from other neurons in the recorded network and of modulation by an external stimulus. The coupling terms arising from synaptic input can be transformed by thresholding into a binary connectivity matrix which is directed. Each link between two neurons represents a causal influence from one neuron to the other, given the observation of all other neurons from the population. The resulting graph is analyzed with respect to small-world and scale-free properties using quantitative measures for directed networks. Such graph-theoretic analyses have been performed on many complex dynamic networks, including the connectivity structure between different brain areas. Only few studies have attempted to look at the structure of cortical neural networks on the level of individual neurons. Here, using multi-electrode recordings from the visual system of the awake monkey, we find that cortical networks lack scale-free behavior, but show a small, but significant small-world structure. Assuming a simple distance-dependent probabilistic wiring between neurons, we find that this connectivity structure can account for all of the networks' observed small-world-ness. Moreover, for multi-electrode recordings the sampling of neurons is not uniform across the population. We show that the small-world-ness obtained by such a localized sub-sampling overestimates the strength of the true small-world-structure of the network. This bias is likely to be present in all previous experiments based on multi-electrode recordings.

  16. The small-world effect is a modern phenomenon

    CERN Document Server

    Marvel, Seth A; Doering, Charles R; Lusseau, David; Newman, M E J

    2013-01-01

    The "small-world effect" is the observation that one can find a short chain of acquaintances, often of no more than a handful of individuals, connecting almost any two people on the planet. It is often expressed in the language of networks, where it is equivalent to the statement that most pairs of individuals are connected by a short path through the acquaintance network. Although the small-world effect is well-established empirically for contemporary social networks, we argue here that it is a relatively recent phenomenon, arising only in the last few hundred years: for most of mankind's tenure on Earth the social world was large, with most pairs of individuals connected by relatively long chains of acquaintances, if at all. Our conclusions are based on observations about the spread of diseases, which travel over contact networks between individuals and whose dynamics can give us clues to the structure of those networks even when direct network measurements are not available. As an example we consider the s...

  17. Movement: How the Brain Communicates with the World.

    Science.gov (United States)

    Schwartz, Andrew B

    2016-03-10

    Voluntary movement is a result of signals transmitted through a communication channel that links the internal world in our minds to the physical world around us. Intention can be considered the desire to effect change on our environment, and this is contained in the signals from the brain, passed through the nervous system to converge on muscles that generate displacements and forces on our surroundings. The resulting changes in the world act to generate sensations that feed back to the nervous system, closing the control loop. This Perspective discusses the experimental and theoretical underpinnings of current models of movement generation and the way they are modulated by external information. Movement systems embody intentionality and prediction, two factors that are propelling a revolution in engineering. Development of movement models that include the complexities of the external world may allow a better understanding of the neuronal populations regulating these processes, as well as the development of solutions for autonomous vehicles and robots, and neural prostheses for those who are motor impaired.

  18. Relative brain size, gut size, and evolution in New World monkeys.

    Science.gov (United States)

    Hartwig, Walter; Rosenberger, Alfred L; Norconk, Marilyn A; Owl, Marcus Young

    2011-12-01

    The dynamics of brain evolution in New World monkeys are poorly understood. New data on brain weight and body weight from 162 necropsied adult individuals, and a second series on body weight and gut size from 59 individuals, are compared with previously published reports based on smaller samples as well as large databases derived from museum records. We confirm elevated brain sizes for Cebus and Saimiri and also report that Cacajao and Chiropotes have relatively large brains. From more limited data we show that gut size and brain mass have a strongly inverse relationship at the low end of the relative brain size scale but a more diffuse interaction at the upper end, where platyrrhines with relatively high encephalization quotients may have either relatively undifferentiated guts or similar within-gut proportions to low-EQ species. Three of the four main platyrrhine clades exhibit a wide range of relative brain sizes, suggesting each may have differentiated while brains were relatively small and a multiplicity of forces acting to maintain or drive encephalization. Alouatta is a likely candidate for de-encephalization, although its "starting point" is difficult to establish. Factors that may have compelled parallel evolution of relatively large brains in cebids, atelids and pitheciids may involve large social group sizes as well as complex foraging strategies, with both aspects exaggerated in the hyper-encephalized Cebus. With diet playing an important role selecting for digestive strategies among the seed-eating pitheciins, comparable in ways to folivores, Chiropotes evolved a relatively larger brain in conjunction with a moderately large and differentiated gut.

  19. Cerebral complexity preceded enlarged brain size and reduced olfactory bulbs in Old World monkeys.

    Science.gov (United States)

    Gonzales, Lauren A; Benefit, Brenda R; McCrossin, Monte L; Spoor, Fred

    2015-07-03

    Analysis of the only complete early cercopithecoid (Old World monkey) endocast currently known, that of 15-million-year (Myr)-old Victoriapithecus, reveals an unexpectedly small endocranial volume (ECV) relative to body size and a large olfactory bulb volume relative to ECV, similar to extant lemurs and Oligocene anthropoids. However, the Victoriapithecus brain has principal and arcuate sulci of the frontal lobe not seen in the stem catarrhine Aegyptopithecus, as well as a distinctive cercopithecoid pattern of gyrification, indicating that cerebral complexity preceded encephalization in cercopithecoids. Since larger ECVs, expanded frontal lobes, and reduced olfactory bulbs are already present in the 17- to 18-Myr-old ape Proconsul these features evolved independently in hominoids (apes) and cercopithecoids and much earlier in the former. Moreover, the order of encephalization and brain reorganization was apparently different in hominoids and cercopithecoids, showing that brain size and cerebral organization evolve independently.

  20. Small-world patterns in Chinese phrase networks

    Institute of Scientific and Technical Information of China (English)

    LI Yong; WEI Luoxia; LI Wei; NIU Yi; LUO Shiyu

    2005-01-01

    @@ Recently, the structure and function of complex networks have become one of the hottest topics in statistical physics and interdisciplinary sciences[1-5]. Studies have shown that real networks containing a huge mount of nodes do not form and evolve in a random way as expected, but they display peculiar features. The most surprising one is the small-world effect, which is commonly shared by food webs[1], the web of human sexual contacts[2], word networks[3], etc. Moreover, the scale-free property of degree distributions also emerges on Internet and protein networks[6,7].

  1. Delay Induced Hopf Bifurcation of Small-World Networks

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, the stability and the Hopf bifurcation of small-world networks with time delay are studied. By analyzing the change of delay, we obtain several sufficient conditions on stable and unstable properties. When the delay passes a critical value, a Hopf bifurcation may appear. Furthermore, the direction and the stability of bifurcating periodic solutions are investigated by the normal form theory and the center manifold reduction. At last, by numerical simulations, we further illustrate the effectiveness of theorems in this paper.

  2. Modular Epidemic Spreading in Small-World Networks

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hui; GAO Zi-You

    2007-01-01

    We study the epidemic spreading of the susceptible-infected-susceptible model on small-world networks with modular structure.It is found that the epidemic threshold increases linearly with the modular strength.Furthermore,the modular structure may influence the infected density in the steady state and the spreading velocity at the beginning of propagation.Practically,the propagation can be hindered by strengthening the modular structure in the view of network topology.In addition,to reduce the probability of reconnection between modules may also help to control the propagation.

  3. Phase multistability in a dynamical small world network

    Energy Technology Data Exchange (ETDEWEB)

    Shabunin, A. V., E-mail: shabuninav@info.sgu.ru [Radiophysics and Nonlinear Dynamics Department, Saratov State University, Saratov (Russian Federation)

    2015-01-15

    The effect of phase multistability is explored in a small world network of periodic oscillators with diffusive couplings. The structure of the network represents a ring with additional non-local links, which spontaneously arise and vanish between arbitrary nodes. The dynamics of random couplings is modeled by “birth” and “death” stochastic processes by means of the cellular automate approach. The evolution of the network under gradual increasing of the number of random couplings goes through stages of phases fluctuations and spatial cluster formation. Finally, in the presence of non-local couplings the phase multistability “dies” and only the in-phase regime survives.

  4. Corona graphs as a model of small-world networks

    Science.gov (United States)

    Lv, Qian; Yi, Yuhao; Zhang, Zhongzhi

    2015-11-01

    We introduce recursive corona graphs as a model of small-world networks. We investigate analytically the critical characteristics of the model, including order and size, degree distribution, average path length, clustering coefficient, and the number of spanning trees, as well as Kirchhoff index. Furthermore, we study the spectra for the adjacency matrix and the Laplacian matrix for the model. We obtain explicit results for all the quantities of the recursive corona graphs, which are similar to those observed in real-life networks.

  5. SWIM: A Simple Model to Generate Small Mobile Worlds

    CERN Document Server

    Mei, Alessandro

    2008-01-01

    This paper presents small world in motion (SWIM), a new mobility model for ad-hoc networking. SWIM is relatively simple, is easily tuned by setting just a few parameters, and generates traces that look real--synthetic traces have the same statistical properties of real traces. SWIM shows both experimentally and theoretically the presence of the power law and exponential decay dichotomy of inter-contact times, and, most importantly, our experiments show that it can predict very accurately the performance of forwarding protocols.

  6. Human brain evolution writ large and small.

    Science.gov (United States)

    Sherwood, Chet C; Bauernfeind, Amy L; Bianchi, Serena; Raghanti, Mary Ann; Hof, Patrick R

    2012-01-01

    Human evolution was marked by an extraordinary increase in total brain size relative to body size. While it is certain that increased encephalization is an important factor contributing to the origin of our species-specific cognitive abilities, it is difficult to disentangle which aspects of human neural structure and function are correlated by-products of brain size expansion from those that are specifically related to particular psychological specializations, such as language and enhanced "mentalizing" abilities. In this chapter, we review evidence from allometric scaling studies demonstrating that much of human neocortical organization can be understood as a product of brain enlargement. Defining extra-allometric specializations in humans is often hampered by a severe lack of comparative data from the same neuroanatomical variables across a broad range of primates. When possible, we highlight evidence for features of human neocortical architecture and function that cannot be easily explained as correlates of brain size and, hence, might be more directly associated with the evolution of uniquely human cognitive capacities. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Small-world phenomena in physics: the Ising model

    Energy Technology Data Exchange (ETDEWEB)

    Gitterman, M. [Department of Physics, Bar-Ilan University, Ramat-Gan (Israel)

    2000-12-01

    The Ising system with a small fraction of random long-range interactions is the simplest example of small-world phenomena in physics. Considering the latter both in an annealed and in a quenched state we conclude that: (a) the existence of random long-range interactions leads to a phase transition in the one-dimensional case and (b) there is a minimal average number p of these interactions per site (p<1 in the annealed state, and p{approx_equal}1 in the quenched state) needed for the appearance of the phase transition. Note that the average number of these bonds, pN/2, is much smaller than the total number of bonds, N{sup 2}/2. (author)

  8. Electron Transport through Models for Small-World Nanomaterials

    Science.gov (United States)

    Solomon, Lazarus; Novotny, Mark

    2008-03-01

    We investigate the quantum transport of (spinless) electrons through simplified models related to small-world nanomaterials. We employ a tight-binding Hamiltonian, and obtain the transmission coefficient from a matrix solution of the associated time-independent Schrödinger Equation. The system studied corresponds to d=1 semi-infinite input and output leads, connected to a `blob' of N atoms. We first present exact results for N inter-connected atoms, a fully-connected graph. The exact solution, for any N, is given both for symmetric and non-symmetric connections between the `blob' and the input/output. We then present numerical results obtained by removing some of the connections within the N-site `blob', thereby approaching transport through a small-world nanomaterial [1-4]. [1] S. Caliskan, M.A. Novotny, and J.I. Cerd'a, J. Appl. Phys., 102, 013707 (2007). [2] M.A. Novotny et al., J. Appl. Phys., 97, 10B309 (2005). [3] M.A. Novotny and S.M. Wheeler, Braz. J. Physics 34, 395 (2004). [4] J. Yancey, M.A. Novotny, and S.R. Gwaltney, 2008 March Meeting presentation.

  9. Structure of Small World Innovation Network and Learning Performance

    Directory of Open Access Journals (Sweden)

    Shuang Song

    2014-01-01

    Full Text Available This paper examines the differences of learning performance of 5 MNCs (multinational corporations that filed the largest number of patents in China. We establish the innovation network with the patent coauthorship data by these 5 MNCs and classify the networks by the tail of distribution curve of connections. To make a comparison of the learning performance of these 5 MNCs with differing network structures, we develop an organization learning model by regarding the reality as having m dimensions, which denotes the heterogeneous knowledge about the reality. We further set n innovative individuals that are mutually interactive and own unique knowledge about the reality. A longer (shorter distance between the knowledge of the individual and the reality denotes a lower (higher knowledge level of that individual. Individuals interact with and learn from each other within the small-world network. By making 1,000 numerical simulations and averaging the simulated results, we find that the differing structure of the small-world network leads to the differences of learning performance between these 5 MNCs. The network monopolization negatively impacts and network connectivity positively impacts learning performance. Policy implications in the conclusion section suggest that to improve firm learning performance, it is necessary to establish a flat and connective network.

  10. Altered small-world properties of gray matter networks in breast cancer

    Directory of Open Access Journals (Sweden)

    Hosseini S M

    2012-05-01

    Full Text Available Abstract Background Breast cancer survivors, particularly those treated with chemotherapy, are at significantly increased risk for long-term cognitive and neurobiologic impairments. These deficits tend to involve skills that are subserved by distributed brain networks. Additionally, neuroimaging studies have shown a diffuse pattern of brain structure changes in chemotherapy-treated breast cancer survivors that might impact large-scale brain networks. Methods We therefore applied graph theoretical analysis to compare the gray matter structural networks of female breast cancer survivors with a history of chemotherapy treatment and healthy age and education matched female controls. Results Results revealed reduced clustering coefficient and small-world index in the brain network of the breast cancer patients across a range of network densities. In addition, the network of the breast cancer group had less highly interactive nodes and reduced degree/centrality in the frontotemporal regions compared to controls, which may help explain the common impairments of memory and executive functioning among these patients. Conclusions These results suggest that breast cancer and chemotherapy may decrease regional connectivity as well as global network organization and integration, reducing efficiency of the network. To our knowledge, this is the first report of altered large-scale brain networks associated with breast cancer and chemotherapy.

  11. CXCR4/CXCL12 in Non-Small-Cell Lung Cancer Metastasis to the Brain

    Directory of Open Access Journals (Sweden)

    Sebastiano Cavallaro

    2013-01-01

    Full Text Available Lung cancer represents the leading cause of cancer-related mortality throughout the world. Patients die of local progression, disseminated disease, or both. At least one third of the people with lung cancer develop brain metastases at some point during their disease, even often before the diagnosis of lung cancer is made. The high rate of brain metastasis makes lung cancer the most common type of tumor to spread to the brain. It is critical to understand the biologic basis of brain metastases to develop novel diagnostic and therapeutic approaches. This review will focus on the emerging data supporting the involvement of the chemokine CXCL12 and its receptor CXCR4 in the brain metastatic evolution of non-small-cell lung cancer (NSCLC and the pharmacological tools that may be used to interfere with this signaling axis.

  12. Study Under AC Stimulation on Excitement Properties of Weighted Small-World Biological Neural Networks with Side-Restrain Mechanism

    Institute of Scientific and Technical Information of China (English)

    YUAN Wu-Jie; LUO Xiao-Shu; JIANG Pin-Qun

    2007-01-01

    In this paper,we propose a new model of weighted small-world biological neural networks based on biophysical Hodgkin-Huxley neurons with side-restrain mechanism.Then we study excitement properties of the model under alternating current (AC) stimulation.The study shows that the excitement properties in the networks are preferably consistent with the behavior properties of a brain nervous system under different AC stimuli,such as refractory period and the brain neural excitement response induced by different intensities of nolse and coupling.The results of the study have reference worthiness for the brain nerve electrophysiology and epistemological science.

  13. The Griffiths Phase on Hierarchical Modular Networks with Small-world Edges

    CERN Document Server

    Li, Shanshan

    2016-01-01

    The Griffiths phase has been proposed to induce a stretched critical regime that facilitates self organizing of brain networks for optimal function. This phase stems from the intrinsic structural heterogeneity of brain networks, such as the hierarchical modular structure. In this work, we extend this concept to modified hierarchical networks with small-world connections based on Hanoi networks [1]. Through extensive simulations, we identify the essential role played by the exponential distribution of the inter-moduli connectivity probability across hierarchies on the emergence of the Griffiths phase in this network. Additionally, the spectral analysis on the adjacency matrix of the relevant networks [2] shows that a localized principle eigenvector is not necessarily the fingerprint of the Griffiths phase.

  14. Brain-to-Brain Synchrony Tracks Real-World Dynamic Group Interactions in the Classroom.

    Science.gov (United States)

    Dikker, Suzanne; Wan, Lu; Davidesco, Ido; Kaggen, Lisa; Oostrik, Matthias; McClintock, James; Rowland, Jess; Michalareas, Georgios; Van Bavel, Jay J; Ding, Mingzhou; Poeppel, David

    2017-05-08

    The human brain has evolved for group living [1]. Yet we know so little about how it supports dynamic group interactions that the study of real-world social exchanges has been dubbed the "dark matter of social neuroscience" [2]. Recently, various studies have begun to approach this question by comparing brain responses of multiple individuals during a variety of (semi-naturalistic) tasks [3-15]. These experiments reveal how stimulus properties [13], individual differences [14], and contextual factors [15] may underpin similarities and differences in neural activity across people. However, most studies to date suffer from various limitations: they often lack direct face-to-face interaction between participants, are typically limited to dyads, do not investigate social dynamics across time, and, crucially, they rarely study social behavior under naturalistic circumstances. Here we extend such experimentation drastically, beyond dyads and beyond laboratory walls, to identify neural markers of group engagement during dynamic real-world group interactions. We used portable electroencephalogram (EEG) to simultaneously record brain activity from a class of 12 high school students over the course of a semester (11 classes) during regular classroom activities (Figures 1A-1C; Supplemental Experimental Procedures, section S1). A novel analysis technique to assess group-based neural coherence demonstrates that the extent to which brain activity is synchronized across students predicts both student class engagement and social dynamics. This suggests that brain-to-brain synchrony is a possible neural marker for dynamic social interactions, likely driven by shared attention mechanisms. This study validates a promising new method to investigate the neuroscience of group interactions in ecologically natural settings. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Abnormal small-world architecture of top-down control networks in obsessive-compulsive disorder.

    Science.gov (United States)

    Zhang, Tijiang; Wang, Jinhui; Yang, Yanchun; Wu, Qizhu; Li, Bin; Chen, Long; Yue, Qiang; Tang, Hehan; Yan, Chaogan; Lui, Su; Huang, Xiaoqi; Chan, Raymond C K; Zang, Yufeng; He, Yong; Gong, Qiyong

    2011-01-01

    Obsessive-compulsive disorder (OCD) is a common neuropsychiatric disorder that is characterized by recurrent intrusive thoughts, ideas or images and repetitive ritualistic behaviours. Although focal structural and functional abnormalities in specific brain regions have been widely studied in populations with OCD, changes in the functional relations among them remain poorly understood. This study examined OCD-related alterations in functional connectivity patterns in the brain's top-down control network. We applied resting-state functional magnetic resonance imaging to investigate the correlation patterns of intrinsic or spontaneous blood oxygen level-dependent signal fluctuations in 18 patients with OCD and 16 healthy controls. The brain control networks were first constructed by thresholding temporal correlation matrices of 39 brain regions associated with top-down control and then analyzed using graph theory-based approaches. Compared with healthy controls, the patients with OCD showed decreased functional connectivity in the posterior temporal regions and increased connectivity in various control regions such as the cingulate, precuneus, thalamus and cerebellum. Furthermore, the brain's control networks in the healthy controls showed small-world architecture (high clustering coefficients and short path lengths), suggesting an optimal balance between modularized and distributed information processing. In contrast, the patients with OCD showed significantly higher local clustering, implying abnormal functional organization in the control network. Further analysis revealed that the changes in network properties occurred in regions of increased functional connectivity strength in patients with OCD. The patient group in the present study was heterogeneous in terms of symptom clusters, and most of the patients with OCD were medicated. Our preliminary results suggest that the organizational patterns of intrinsic brain activity in the control networks are altered in

  16. Mandala Networks: ultra-small-world and highly sparse graphs

    Science.gov (United States)

    Sampaio Filho, Cesar I. N.; Moreira, André A.; Andrade, Roberto F. S.; Herrmann, Hans J.; Andrade, José S.

    2015-03-01

    The increasing demands in security and reliability of infrastructures call for the optimal design of their embedded complex networks topologies. The following question then arises: what is the optimal layout to fulfill best all the demands? Here we present a general solution for this problem with scale-free networks, like the Internet and airline networks. Precisely, we disclose a way to systematically construct networks which are robust against random failures. Furthermore, as the size of the network increases, its shortest path becomes asymptotically invariant and the density of links goes to zero, making it ultra-small world and highly sparse, respectively. The first property is ideal for communication and navigation purposes, while the second is interesting economically. Finally, we show that some simple changes on the original network formulation can lead to an improved topology against malicious attacks.

  17. Structured information in small-world neural networks

    Science.gov (United States)

    Dominguez, David; González, Mario; Serrano, Eduardo; Rodríguez, Francisco B.

    2009-02-01

    The retrieval abilities of spatially uniform attractor networks can be measured by the global overlap between patterns and neural states. However, we found that nonuniform networks, for instance, small-world networks, can retrieve fragments of patterns (blocks) without performing global retrieval. We propose a way to measure the local retrieval using a parameter that is related to the fluctuation of the block overlaps. Simulation of neural dynamics shows a competition between local and global retrieval. The phase diagram shows a transition from local retrieval to global retrieval when the storage ratio increases and the topology becomes more random. A theoretical approach confirms the simulation results and predicts that the stability of blocks can be improved by dilution.

  18. Characteristics of Preferentially Attached Network Grown from Small World

    CERN Document Server

    Lee, Seungyoung

    2015-01-01

    We introduce a model for a preferentially attached network which has grown from a small world network. Here, the average path length and the clustering coefficient are estimated, and the topological properties of modeled networks are compared as the initial conditions are changed. As a result, it is shown that the topological properties of the initial network remain even after the network growth. However, the vulnerability of each to preferentially attached nodes being added is not the same. It is found that the average path length rapidly decreases as the ratio of preferentially attached nodes increases and that the characteristics of the initial network can be easily disappeared. On the other hand, the clustering coefficient of the initial network slowly decreases with the ratio of preferentially attached nodes and its clustering characteristic remains much longer.

  19. The structure of borders in a small world

    CERN Document Server

    Thiemann, C; Grady, D; Brune, R; Brockmann, D

    2010-01-01

    Geographic borders are not only essential for the effective functioning of government, the distribution of administrative responsibilities and the allocation of public resources, they also influence the interregional flow of information, cross-border trade operations, the diffusion of innovation and technology, and the spatial spread of infectious diseases. However, as growing interactions and mobility across long distances, cultural, and political borders continue to amplify the small world effect and effectively decrease the relative importance of local interactions, it is difficult to assess the location and structure of effective borders that may play the most significant role in mobility-driven processes. The paradigm of spatially coherent communities may no longer be a plausible one, and it is unclear what structures emerge from the interplay of interactions and activities across spatial scales. Here we analyse a multi-scale proxy network for human mobility that incorporates travel across a few to a few...

  20. Neural progenitors organize in small-world networks to promote cell proliferation.

    Science.gov (United States)

    Malmersjö, Seth; Rebellato, Paola; Smedler, Erik; Planert, Henrike; Kanatani, Shigeaki; Liste, Isabel; Nanou, Evanthia; Sunner, Hampus; Abdelhady, Shaimaa; Zhang, Songbai; Andäng, Michael; El Manira, Abdeljabbar; Silberberg, Gilad; Arenas, Ernest; Uhlén, Per

    2013-04-16

    Coherent network activity among assemblies of interconnected cells is essential for diverse functions in the adult brain. However, cellular networks before formations of chemical synapses are poorly understood. Here, embryonic stem cell-derived neural progenitors were found to form networks exhibiting synchronous calcium ion (Ca(2+)) activity that stimulated cell proliferation. Immature neural cells established circuits that propagated electrical signals between neighboring cells, thereby activating voltage-gated Ca(2+) channels that triggered Ca(2+) oscillations. These network circuits were dependent on gap junctions, because blocking prevented electrotonic transmission both in vitro and in vivo. Inhibiting connexin 43 gap junctions abolished network activity, suppressed proliferation, and affected embryonic cortical layer formation. Cross-correlation analysis revealed highly correlated Ca(2+) activities in small-world networks that followed a scale-free topology. Graph theory predicts that such network designs are effective for biological systems. Taken together, these results demonstrate that immature cells in the developing brain organize in small-world networks that critically regulate neural progenitor proliferation.

  1. Small-World Effect of Complex Network and Its Application toProtein Folding

    Institute of Scientific and Technical Information of China (English)

    卢全国; 陈宝方; 彭华魁; 祖巧红

    2004-01-01

    The famous "six letters" experiment carried out by Milgram demonstrated the existence of small-world effect in a complex network. One vertex tends to be connected to another by a shortest path through network because of the small-world effect. This paper uses the small-world effect to study protein folding pathway.

  2. Multiobjective Bak-Sneppen model on a small-world network

    Energy Technology Data Exchange (ETDEWEB)

    Elettreby, M.F. [Department of Mathematics, Faculty of Science, Mansoura University, Mansoura 35516 (Egypt)] e-mail: mohfathy@mans.edu.eg

    2005-11-01

    Small-world networks (SWN) are relevant to biological systems. We study the dynamics of the Bak-Sneppen (BS) model on small-world network, including the concepts of extremal dynamics, multiobjective optimization and coherent noise. We find that the small-world structure stabilizes the system. Also, it is more realistic to augment the Bak-Sneppen model by these concepts.

  3. Braess like Paradox in a Small World Network

    CERN Document Server

    Toyota, Norihito

    2013-01-01

    Braess \\cite{1} has been studied about a traffic flow on a diamond type network and found that introducing new edges to the networks always does not achieve the efficiency. Some researchers studied the Braess' paradox in similar type networks by introducing various types of cost functions. But whether such paradox occurs or not is not scarcely studied in complex networks. In this article, I analytically and numerically study whether Braess like paradox occurs or not on Dorogovtsev-Mendes network\\cite{2}, which is a sort of small world networks. The cost function needed to go along an edge is postulated to be equally identified with the length between two nodes, independently of an amount of traffic on the edge. It is also assumed the it takes a certain cost $c$ to pass through the center node in Dorogovtsev-Mendes network. If $c$ is small, then bypasses have the function to provide short cuts. As result of numerical and theoretical analyses, while I find that any Braess' like paradox will not occur when the n...

  4. Small vessel ischemic disease of the brain and brain metastases in lung cancer patients.

    Directory of Open Access Journals (Sweden)

    Peter J Mazzone

    Full Text Available BACKGROUND: Brain metastases occur commonly in patients with lung cancer. Small vessel ischemic disease is frequently found when imaging the brain to detect metastases. We aimed to determine if the presence of small vessel ischemic disease (SVID of the brain is protective against the development of brain metastases in lung cancer patients. METHODOLOGY/PRINCIPAL FINDINGS: A retrospective cohort of 523 patients with biopsy confirmed lung cancer who had received magnetic resonance imaging of the brain as part of their standard initial staging evaluation was reviewed. Information collected included demographics, comorbidities, details of the lung cancer, and the presence of SVID of the brain. A portion of the cohort had the degree of SVID graded. The primary outcome measure was the portion of study subjects with and without SVID of the brain who had evidence of brain metastases at the time of initial staging of their lung cancer.109 patients (20.8% had evidence of brain metastases at presentation and 345 (66.0% had evidence of SVID. 13.9% of those with SVID and 34.3% of those without SVID presented with brain metastases (p<0.0001. In a model including age, diabetes mellitus, hypertension, hyperlipidemia, and tobacco use, SVID of the brain was found to be the only protective factor against the development of brain metastases, with an OR of 0.31 (0.20, 0.48; p<0.001. The grade of SVID was higher in those without brain metastases. CONCLUSIONS/SIGNIFICANCE: These findings suggest that vascular changes in the brain are protective against the development of brain metastases in lung cancer patients.

  5. Relapsing pattern of brain metastasis after brain irradiation in small cell lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Masao; Kuroda, Yasumasa; Okamoto, Yoshiaki; Kono, Koichi; Yoden, Eisaku; Mori, Takeki [Tenri Hospital, Nara (Japan)

    1997-03-01

    Many reports concerning radiation therapy for brain metastasis have been published, and which of the various methods urged by these reports provide optional control is still controversial. According to developing diagnosis of metastasis in CNS, therapeutic problems should be referred. We reviewed 67 patients with small cell lung cancer and brain metastasis who underwent brain irradiation (Ave. 47 Gy/5W), and all 15 patients with brain relapse after the irradiation. Relapsing patterns in this clinical setting were divided into local regrowth in the same lesions and re-metastasis (reseeding) in other regions, by reviewing follow up CT and MRI studies. Total survival among 15 patients with brain relapse and 52 without relapse was longer in the former cases than the later: 1-, and 2-year survival (47/19%, 13/8%) and MST (10.8/5.7 months), from the initial brain irradiation. The concerned significant factors limited in younger age, low value of LDH and improvement of NF. Of the 15 patients with brain relapse, 4 developed local regrowth and 11 did re-metastasis. The period of remission since brain irradiation were 172{+-}94.4 and 393{+-}281 days, respectively. Lower number of brain metastasis and lower value of LDH were shown in re-metastasis patients. At the time of brain relapse, 11 patients had recurrence of carcinomatous meningitis. 4 patients were treated with whole brain re-irradiation. All patients died of cancer, including 12 of relapsing CNS diseases and 3 of primary lesion and hepatic metastasis. Leukoencephalopathy developed in 2 patients. Survival since the brain relapse was 2 to 238 days without significant difference in cases of local regrowth and re-metastasis. According to our data on relapsing pattern of brain metastasis after conventional fractionated brain irradiation with an objective dose of 50 Gy, 75% of brain relapse were re-metastasis, we appreciate this irradiation for initial brain metastasis if limited to the brain. (author)

  6. Small-World and Scale-Free Network Models for IoT Systems

    Directory of Open Access Journals (Sweden)

    Insoo Sohn

    2017-01-01

    Full Text Available It is expected that Internet of Things (IoT revolution will enable new solutions and business for consumers and entrepreneurs by connecting billions of physical world devices with varying capabilities. However, for successful realization of IoT, challenges such as heterogeneous connectivity, ubiquitous coverage, reduced network and device complexity, enhanced power savings, and enhanced resource management have to be solved. All these challenges are heavily impacted by the IoT network topology supported by massive number of connected devices. Small-world networks and scale-free networks are important complex network models with massive number of nodes and have been actively used to study the network topology of brain networks, social networks, and wireless networks. These models, also, have been applied to IoT networks to enhance synchronization, error tolerance, and more. However, due to interdisciplinary nature of the network science, with heavy emphasis on graph theory, it is not easy to study the various tools provided by complex network models. Therefore, in this paper, we attempt to introduce basic concepts of graph theory, including small-world networks and scale-free networks, and provide system models that can be easily implemented to be used as a powerful tool in solving various research problems related to IoT.

  7. Abnormal small-world architecture of top–down control networks in obsessive–compulsive disorder

    Science.gov (United States)

    Zhang, Tijiang; Wang, Jinhui; Yang, Yanchun; Wu, Qizhu; Li, Bin; Chen, Long; Yue, Qiang; Tang, Hehan; Yan, Chaogan; Lui, Su; Huang, Xiaoqi; Chan, Raymond C.K.; Zang, Yufeng; He, Yong; Gong, Qiyong

    2011-01-01

    Background Obsessive–compulsive disorder (OCD) is a common neuropsychiatric disorder that is characterized by recurrent intrusive thoughts, ideas or images and repetitive ritualistic behaviours. Although focal structural and functional abnormalities in specific brain regions have been widely studied in populations with OCD, changes in the functional relations among them remain poorly understood. This study examined OCD–related alterations in functional connectivity patterns in the brain’s top–down control network. Methods We applied resting-state functional magnetic resonance imaging to investigate the correlation patterns of intrinsic or spontaneous blood oxygen level–dependent signal fluctuations in 18 patients with OCD and 16 healthy controls. The brain control networks were first constructed by thresholding temporal correlation matrices of 39 brain regions associated with top–down control and then analyzed using graph theory-based approaches. Results Compared with healthy controls, the patients with OCD showed decreased functional connectivity in the posterior temporal regions and increased connectivity in various control regions such as the cingulate, precuneus, thalamus and cerebellum. Furthermore, the brain’s control networks in the healthy controls showed small-world architecture (high clustering coefficients and short path lengths), suggesting an optimal balance between modularized and distributed information processing. In contrast, the patients with OCD showed significantly higher local clustering, implying abnormal functional organization in the control network. Further analysis revealed that the changes in network properties occurred in regions of increased functional connectivity strength in patients with OCD. Limitations The patient group in the present study was heterogeneous in terms of symptom clusters, and most of the patients with OCD were medicated. Conclusion Our preliminary results suggest that the organizational patterns of

  8. Small World Model-Based Polylogarithmic Routing Using Mobile Nodes

    Institute of Scientific and Technical Information of China (English)

    Jie Wu; Shu-Hui Yang

    2008-01-01

    The use of mobile nodes to improve network system performance has drawn considerable attention recently.The movement-assisted model considers mobility as a desirable feature, where routing is based on the store-carry-forward paradigm with random or controlled movement of resource rich mobile nodes. The application of such a model has been used in several emerging networks, including mobile ad hoc networks (MANETs), wireless sensor networks (WSNs), and delay tolerant networks (DTNs). It is well known that mobility increases the capacity of MANETs by reducing the number of relays for routing, prolonging the lifespan of WSNs by using mobile nodes in place of bottleneck static sensors, and ensuring network connectivity in DTNs using mobile nodes to connect different parts of a disconnected network. Trajectory planning and the coordination of mobile nodes are two important design issues aiming to optimize or balance several measures,including delay, average number of relays, and moving distance. In this paper, we propose a new controlled mobility model with an expected polylogarithmic number of relays to achieve a good balance among several contradictory goals, including delay, the number of relays, and moving distance. The model is based on the small-world model where each static node has "short" link connections to its nearest neighbors and "long" link connections to other nodes following a certain probability distribution. Short links are regular wireless connections whereas long links are implemented using mobile nodes. Various issues are considered, including trade-offs between delay and average number of relays, selection of the number of mobilenodes, and selection of the number of long links. The effectiveness of the proposed model is evaluated analytically as well as through simulation.

  9. Networks of neuroblastoma cells on porous silicon substrates reveal a small world topology

    KAUST Repository

    Marinaro, Giovanni

    2015-01-01

    The human brain is a tightly interweaving network of neural cells where the complexity of the network is given by the large number of its constituents and its architecture. The topological structure of neurons in the brain translates into its increased computational capabilities, low energy consumption, and nondeterministic functions, which differentiate human behavior from artificial computational schemes. In this manuscript, we fabricated porous silicon chips with a small pore size ranging from 8 to 75 nm and large fractal dimensions up to Df ∼ 2.8. In culturing neuroblastoma N2A cells on the described substrates, we found that those cells adhere more firmly to and proliferate on the porous surfaces compared to the conventional nominally flat silicon substrates, which were used as controls. More importantly, we observed that N2A cells on the porous substrates create highly clustered, small world topology patterns. We conjecture that neurons with a similar architecture may elaborate information more efficiently than in random or regular grids. Moreover, we hypothesize that systems of neurons on nano-scale geometry evolve in time to form networks in which the propagation of information is maximized. This journal is

  10. World Standards Day 14 October 2006 Standards: big benefits for small business

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Small business could claim to be the world's biggest business. It is estimated that more than 95 per cent of the world's businesses are small to medium sized. Thus, international standards need to provide as many benefits for small businesses as they do for global enterprises, governments and society at large.

  11. Effects of Small-World Rewiring Probability and Noisy Synaptic Conductivity on Slow Waves: Cortical Network.

    Science.gov (United States)

    Tekin, Ramazan; Tagluk, Mehmet Emin

    2017-03-01

    Physiological rhythms play a critical role in the functional development of living beings. Many biological functions are executed with an interaction of rhythms produced by internal characteristics of scores of cells. While synchronized oscillations may be associated with normal brain functions, anomalies in these oscillations may cause or relate the emergence of some neurological or neuropsychological pathologies. This study was designed to investigate the effects of topological structure and synaptic conductivity noise on the spatial synchronization and temporal rhythmicity of the waves generated by cells in the network. Because of holding the ability of clustering and randomizing with change of parameters, small-world (SW) network topology was chosen. The oscillatory activity of network was tried out by manipulating an insulated SW, cortical network model whose morphology is very close to real world. According to the obtained results, it was observed that at the optimal probabilistic rates of conductivity noise and rewiring of SW, powerful synchronized oscillatory small waves are generated in relation to the internal dynamics of cells, which are in line with the network's input. These two parameters were observed to be quite effective on the excitation-inhibition balance of the network. Accordingly, it may be suggested that the topological dynamics of SW and noisy synaptic conductivity may be associated with the normal and abnormal development of neurobiological structure.

  12. Effects of hybrid synapses on the vibrational resonance in small-world neuronal networks.

    Science.gov (United States)

    Yu, Haitao; Wang, Jiang; Sun, Jianbing; Yu, Haifeng

    2012-09-01

    We investigate the effect of vibrational resonance in small-world neuronal networks with hybrid chemical and electrical synapses. It is shown that, irrespective of the probability of chemical synapses, an optimal amplitude of high-frequency component of the signal can optimize the dynamical response of neuron populations to the low-frequency component, which encodes the information. This effect of vibrational resonance of neuronal systems depends extensively on the network structure and parameters, which determine the ability of neuronal networks to enhance the outreach of localized subthreshold low-frequency signal. In particular, chemical synaptic coupling is more efficient than the electrical coupling for the transmission of local input signal due to its selective coupling. Moreover, there exists an optimal small-world topology characterized by an optimal value of rewiring probability, warranting the largest peak value of the system response. Considering that two-frequency signals are ubiquity in brain dynamics, we expect the presented results could have important implications for signal processing in neuronal systems.

  13. Integration of neuroblasts into a two-dimensional small world neuronal network

    Science.gov (United States)

    Schneider-Mizell, Casey; Zochowski, Michal; Sander, Leonard

    2009-03-01

    Neurogenesis in the adult brain has been suggested to be important for learning and functional robustness to the neuronal death. New neurons integrate themselves into existing neuronal networks by moving into a target destination, extending axonal and dendritic processes, and inducing synaptogenesis to connect to active neurons. We hypothesize that increased plasticity of the network to novel stimuli can arise from activity-dependent cell and process motility rules. In complement to a similar in vitro model, we investigate a computational model of a two-dimensional small world network of integrate and fire neurons. After steady-state activity is reached in the extant network, we introduce new neurons which move, stop, and connect themselves through rules governed by position and firing rate.

  14. Traumatic Brain Injury Studies in Britain during World War II.

    Science.gov (United States)

    Lanska, Douglas J

    2016-01-01

    As a result of the wartime urgency to understand, prevent, and treat patients with traumatic brain injury (TBI) during World War II (WWII), clinicians and basic scientists in Great Britain collaborated on research projects that included accident investigations, epidemiologic studies, and development of animal and physical models. Very quickly, investigators from different disciplines shared information and ideas that not only led to new insights into the mechanisms of TBI but also provided very practical approaches for preventing or ameliorating at least some forms of TBI. Neurosurgeon Hugh Cairns (1896-1952) conducted a series of influential studies on the prevention and treatment of head injuries that led to recognition of a high rate of fatal TBI among motorcycle riders and subsequently to demonstrations of the utility of helmets in lowering head injury incidence and case fatality. Neurologists Derek Denny-Brown (1901-1981) and (William) Ritchie Russell (1903-1980) developed an animal model of TBI that demonstrated the fundamental importance of sudden acceleration (i.e., jerking) of the head in causing concussion and forced a distinction between head injury associated with sudden acceleration/deceleration and that associated with crush or compression. Physicist A.H.S. Holbourn (1907-1962) used theoretical arguments and simple physical models to illustrate the importance of shear stress in TBI. The work of these British neurological clinicians and scientists during WWII had a strong influence on subsequent clinical and experimental studies of TBI and also eventually resulted in effective (albeit controversial) public health campaigns and legislation in several countries to prevent head injuries among motorcycle riders and others through the use of protective helmets. Collectively, these studies accelerated our understanding of TBI and had subsequent important implications for both military and civilian populations. As a result of the wartime urgency to understand

  15. Dynamics in small worlds of tree topologies of wireless sensor networks

    DEFF Research Database (Denmark)

    Li, Qiao; Zhang, Baihai; Fan, Zhun

    2012-01-01

    Tree topologies, which construct spatial graphs with large characteristic path lengths and small clustering coefficients, are ubiquitous in deployments of wireless sensor networks. Small worlds are investigated in tree-based networks. Due to link additions, characteristic path lengths reduce...

  16. Brain-only metastases of small cell lung cancer; efficacy of whole brain radiotherapy. An EORTC phase II study

    NARCIS (Netherlands)

    Postmus, PE; Haaxma-Reiche, H; Gregor, A; Groen, HJM; Lewinski, T; Scolard, T; Kirkpatrick, A; Curran, D; Sahmoud, T; Giaccone, G

    Background and purpose: To evaluate the efficacy of WBRT as a single treatment modality in patients with brain metastases of small cell lung cancer. Patients and methods: The patients had brain metastases of small cell lung cancer without any sign of tumour outside the brain and were treated with 10

  17. Latching chains in K-nearest-neighbor and modular small-world networks.

    Science.gov (United States)

    Song, Sanming; Yao, Hongxun; Simonov, Alexander Yurievich

    2015-01-01

    Latching dynamics retrieve pattern sequences successively by neural adaption and pattern correlation. We have previously proposed a modular latching chain model in Song et al. (2014) to better accommodate the structured transitions in the brain. Different cortical areas have different network structures. To explore how structural parameters like rewiring probability, threshold, noise and feedback connections affect the latching dynamics, two different connection schemes, K-nearest-neighbor network and modular network both having modular structure are considered. Latching chains are measured using two proposed measures characterizing length of intra-modular latching chains and sequential inter-modular association transitions. Our main findings include: (1) With decreasing threshold coefficient and rewiring probability, both the K-nearest-neighbor network and the modular network experience quantitatively similar phase change processes. (2) The modular network exhibits selectively enhanced latching in the small-world range of connectivity. (3) The K-nearest-neighbor network is more robust to changes in rewiring probability, while the modular network is more robust to the presence of noise pattern pairs and to changes in the strength of feedback connections. According to our findings, the relationships between latching chains in K-nearest-neighbor and modular networks and different forms of cognition and information processing emerging in the brain are discussed.

  18. Altered functional connectivity and small-world in mesial temporal lobe epilepsy.

    Directory of Open Access Journals (Sweden)

    Wei Liao

    Full Text Available BACKGROUND: The functional architecture of the human brain has been extensively described in terms of functional connectivity networks, detected from the low-frequency coherent neuronal fluctuations that can be observed in a resting state condition. Little is known, so far, about the changes in functional connectivity and in the topological properties of functional networks, associated with different brain diseases. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we investigated alterations related to mesial temporal lobe epilepsy (mTLE, using resting state functional magnetic resonance imaging on 18 mTLE patients and 27 healthy controls. Functional connectivity among 90 cortical and subcortical regions was measured by temporal correlation. The related values were analyzed to construct a set of undirected graphs. Compared to controls, mTLE patients showed significantly increased connectivity within the medial temporal lobes, but also significantly decreased connectivity within the frontal and parietal lobes, and between frontal and parietal lobes. Our findings demonstrated that a large number of areas in the default-mode network of mTLE patients showed a significantly decreased number of connections to other regions. Furthermore, we observed altered small-world properties in patients, along with smaller degree of connectivity, increased n-to-1 connectivity, smaller absolute clustering coefficients and shorter absolute path length. CONCLUSIONS/SIGNIFICANCE: We suggest that the mTLE alterations observed in functional connectivity and topological properties may be used to define tentative disease markers.

  19. Dreams of Small Nations in a Polycentric Fashion World

    DEFF Research Database (Denmark)

    Skov, Lise

    2011-01-01

    takes on national significance, in terms of staging events and displays, and engaging with cultural references outside the field of fashion. This article explores how such place-making abilities structure the polycentric world of fashion, taking the United Nations Security Council as a model...

  20. Six Degrees of Information Seeking: Stanley Milgram and the Small World of the Library

    Science.gov (United States)

    James, Kathryn

    2006-01-01

    Stanley Milgram's 1967 "small world" social connectivity study is used to analyze information connectivity, or patron information-seeking behavior. The "small world" study, upon examination, offers a clear example of the failure of social connectivity. This failure is used to highlight the importance of the subjectivities of patron experience of…

  1. A geometric growth model interpolating between regular and small-world networks

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhongzhi [Department of Computer Science and Engineering, Fudan University, Shanghai 200433 (China); Zhou, Shuigeng [Department of Computer Science and Engineering, Fudan University, Shanghai 200433 (China); Wang, Zhiyong [Department of Computer Science and Engineering, Fudan University, Shanghai 200433 (China); Shen, Zhen [Department of Computer Science and Engineering, Fudan University, Shanghai 200433 (China)

    2007-09-28

    We propose a geometric growth model which interpolates between one-dimensional linear graphs and small-world networks. The model undergoes a transition from large to small worlds. We study the topological characteristics by both theoretical predictions and numerical simulations, which are in good accordance with each other. Our geometrically growing model is a complementarity for the static WS model.

  2. "Scotland Small? Our Multiform, Our Infinite Scotland Small?" Scotland's Literary Contribution to the Modern World

    Directory of Open Access Journals (Sweden)

    Aniela Korzeniowska

    2015-06-01

    Full Text Available "Scotland Small? Our Multiform, Our Infinite Scotland Small?" Scotland's Literary Contribution to the Modern World Hugh MacDiarmid’s poem "Scotland Small?" (1943 questions the widespread opinion at the time that Scotland was only a small country geographically with "nothing but heather!", showing how "marvellously descriptive" this may be, but also totally "incomplete". The issue addressed in this article is how Scottish letters, starting with the outstanding and multiform writings of the same Hugh MacDiarmid (Christopher Murray Grieve [1892-1978] and ending with observations of the international significance of such contemporary Scottish poets as Carol Ann Duffy (b. 1955, the first female to become British Poet Laureate, have contributed to the development and diversity of literature far beyond the borders of Scotland. It is also in looking at the achievements of such diverse writers as Muriel Spark, James Kelman and Ian Rankin as well as poets Ian Hamilton Finlay, Edwin Morgan, Jackie Kay, or the present Scottish Poet Laureate Liz Lochhead, among others, that we can see how significant their literary oeuvre is for a better understanding of the modern world. Emphasis is also placed on the fact that although Scotland is undoubtedly a small country geographically, we can never – in reference to the title of this volume – say it is minor. „Szkocja mała? Nasza wielopostaciowa, bezmierna Szkocja mała?” Literacki wkład Szkocji do współczesnego świata Wiersz Hugh MacDiarmid’a Szkocja mała? (1943 kwestionuje ogólnopanującą opinię w pierwszej połowie XX wieku, że Szkocja to tylko mały kraj, gdzie „nie ma nic innego poza wrzosem”, pokazując jednocześnie, że „opis może i jest wspaniały”, ale także wielce „niekompletny”. Temat niniejszego artykułu opisuje, jak literatura szkocka, poczynając właśnie od wybitnej i wielorakiej twórczości MacDiarmid’a (Christopher Murray Grieve [1892- 1978], a kończąc na mi

  3. Statistics for Small States : A Supplement to the World Development Indicators 2009

    OpenAIRE

    World Bank

    2009-01-01

    In 2000 the World Bank made a corporate commitment to organize a small states Forum each year in the context of the International Monetary Fund (IMF) and World Bank annual meetings. The forum is intended to raise the profile of small states issues and provide an opportunity for small state officials to bring their views and ideas to the attention of the international community. Forty-eight ...

  4. A Summary Report on Contemporary World Small Arms

    Science.gov (United States)

    1982-02-01

    DRSAR-LEP-L Rock Island, IL 61299 Director U.S. Army TRADOC Systems Analysis Activity ATTN: ATAA-SL White Sands Missile Range, NM 88002 5 37 ...exists to make a night sight ( starlite scope) and to build-in a laser rangefinder. Whether it can be made small, light, rugged and cheap enough to

  5. Local Interactions and the Emergence of a Twitter Small-World Network

    CERN Document Server

    Ch'ng, Eugene

    2015-01-01

    The small-world phenomenon is found in many self-organising systems. Systems configured in small-world networks spread information more easily than in random or regular lattice-type networks. Whilst it is a known fact that small-world networks have short average path length and high clustering coefficient in self-organising systems, the ego centralities that maintain the cohesiveness of small-world network have not been formally defined. Here we show that instantaneous events such as the release of news items via Twitter, coupled with active community arguments related to the news item form a particular type of small-world network. Analysis of the centralities in the network reveals that community arguments maintain the small-world network whilst actively maintaining the cohesiveness and boundary of the group. The results demonstrate how an active Twitter community unconsciously forms a small-world network whilst interacting locally with a bordering community. Over time, such local interactions brought about ...

  6. Optimising rigid motion compensation for small animal brain PET imaging

    Science.gov (United States)

    Spangler-Bickell, Matthew G.; Zhou, Lin; Kyme, Andre Z.; De Laat, Bart; Fulton, Roger R.; Nuyts, Johan

    2016-10-01

    Motion compensation (MC) in PET brain imaging of awake small animals is attracting increased attention in preclinical studies since it avoids the confounding effects of anaesthesia and enables behavioural tests during the scan. A popular MC technique is to use multiple external cameras to track the motion of the animal’s head, which is assumed to be represented by the motion of a marker attached to its forehead. In this study we have explored several methods to improve the experimental setup and the reconstruction procedures of this method: optimising the camera-marker separation; improving the temporal synchronisation between the motion tracker measurements and the list-mode stream; post-acquisition smoothing and interpolation of the motion data; and list-mode reconstruction with appropriately selected subsets. These techniques have been tested and verified on measurements of a moving resolution phantom and brain scans of an awake rat. The proposed techniques improved the reconstructed spatial resolution of the phantom by 27% and of the rat brain by 14%. We suggest a set of optimal parameter values to use for awake animal PET studies and discuss the relative significance of each parameter choice.

  7. Cognitive Authority in Everyday Life: From Small Worlds to Virtual Worlds

    Science.gov (United States)

    Meyers, Eric M.

    2010-01-01

    The very nature of information seeking in today's world suggests that credibility is an important factor in how one goes about seeking and using information. The proliferation of Web-based resources and the ability for nearly anyone to publish on the Web force individuals to make judgments of quality and authority as they flow on- and offline in…

  8. A multi-community homogeneous small-world network and its fundamental characteristics

    Science.gov (United States)

    Tanimoto, Jun

    2016-10-01

    We introduce a new small-world network-which we call the multi-community homogeneous-small-world network-that is divided into multiple communities that are relatively isolated, similar to sparsely connected islands. A generating algorithm is presented and its network parameters are explored. To elucidate the fundamental characteristics of the proposed topology, we adopt spatial prisoner's dilemma games as a template for discussion. Comparing with a conventional homogeneous small-world network, more enhanced network reciprocity is observed in games where a stag hunt-type dilemma is large. With intensive analysis, we find how this enhancement is brought about.

  9. Outer synchronization investigation between WS and NW small-world networks with different node numbers

    Science.gov (United States)

    Zhou, Guangye; Li, Chengren; Li, Tingting; Yang, Yi; Wang, Chen; He, Fangjun; Sun, Jingchang

    2016-09-01

    Some typical dual-ring erbium-doped fiber lasers with hyperchaos behaviors are taken as nodes to construct two kinds of small-world networks-NW and WS networks. Based on Lyapunov stability theorem, the appropriate controllers are designed and the outer synchronization between the small-world networks with diverse structures and different node numbers is further investigated. The simulation results show that the perfect synchronization between the complex small-world networks is realized, which is of potential application for all optical communication network.

  10. Growing small-world networks based on a modified BA model

    CERN Document Server

    Xu, Xinping; Li, Wei

    2006-01-01

    We propose a simple growing model for the evolution of small-world networks. It is introduced as a modified BA model in which all the edges connected to the new nodes are made locally to the creator and its nearest neighbors. It is found that this model can produce small-world networks with power-law degree distributions. Properties of our model, including the degree distribution, clustering, and the average path length are compared with that of the BA model. Since most real networks are both scale-free and small-world networks, our model may provide a satisfactory description for empirical characteristics of real networks.

  11. Immunizations on small worlds of tree-based wireless sensor networks

    DEFF Research Database (Denmark)

    Li, Qiao; Zhang, Bai-Hai; Cui, Ling-Guo

    2012-01-01

    , are conducted on small worlds of tree-based wireless sensor networks to combat the sensor viruses. With the former strategy, the infection extends exponentially, although the immunization effectively reduces the contagion speed. With the latter strategy, recurrent contagion oscillations occur in the small world......The sensor virus is a serious threat, as an attacker can simply send a single packet to compromise the entire sensor network. Epidemics become drastic with link additions among sensors when the small world phenomena occur. Two immunization strategies, uniform immunization and temporary immunization...

  12. One small step: world's first integrated EUVL process line

    Science.gov (United States)

    Roberts, Jeanette M.; Bacuita, Terence; Bristol, Robert L.; Cao, Heidi B.; Chandhok, Manish; Lee, Sang H.; Panning, Eric M.; Shell, Melissa; Zhang, Guojing; Rice, Bryan J.

    2005-05-01

    The Intel lithography roadmap calls for Extreme Ultraviolet Lithography (EUVL) to be used for the 32 nm node. With the installation of the EUV Micro-Exposure Tool (MET) complete, Intel now has the world's first integrated EUVL process line including the first commercial EUV exposure tool. This process line will be used to develop the EUV technology, including mask and resist, and to investigate issues such as defect printability. It also provides a test-bed to discover and resolve problems associated with using this novel technology in a fab (not lab) environment. Over 22,000 fields have been exposed, the discharge-produced plasma light source has operated for 50,000,000 pulses, 8 masks have been fabricated, and 8 resists have been characterized. The MET combines high resolution capability with Intel's advanced processing facilities to prepare EUVL for high-volume manufacturing (HVM). In this paper we review the MET installation and facilities, novel capabilities of the linked track, data on optics quality and modeled tool capability, and the MET mask fabrication process. We present data on tool performance including printing 45 nm 1/2 pitch lines with 160 nm depth of focus and 27 nm isolated lines. We show tool accuracy and repeatability data, and discuss issues uncovered during installation and use.

  13. On the relation between the small world structure and scientific activities.

    Science.gov (United States)

    Ebadi, Ashkan; Schiffauerova, Andrea

    2015-01-01

    The modern science has become more complex and interdisciplinary in its nature which might encourage researchers to be more collaborative and get engaged in larger collaboration networks. Various aspects of collaboration networks have been examined so far to detect the most determinant factors in knowledge creation and scientific production. One of the network structures that recently attracted much theoretical attention is called small world. It has been suggested that small world can improve the information transmission among the network actors. In this paper, using the data on 12 periods of journal publications of Canadian researchers in natural sciences and engineering, the co-authorship networks of the researchers are created. Through measuring small world indicators, the small worldiness of the mentioned network and its relation with researchers' productivity, quality of their publications, and scientific team size are assessed. Our results show that the examined co-authorship network strictly exhibits the small world properties. In addition, it is suggested that in a small world network researchers expand their team size through getting connected to other experts of the field. This team size expansion may result in higher productivity of the whole team as a result of getting access to new resources, benefitting from the internal referring, and exchanging ideas among the team members. Moreover, although small world network is positively correlated with the quality of the articles in terms of both citation count and journal impact factor, it is negatively related with the average productivity of researchers in terms of the number of their publications.

  14. Addressing Head Motion Dependencies for Small-World Topologies in Functional Connectomics

    Directory of Open Access Journals (Sweden)

    Chao-Gan eYan

    2013-12-01

    Full Text Available Graph theoretical explorations of functional interactions within the human connectome, are rapidly advancing our understanding of brain architecture. In particular, global and regional topological parameters are increasingly being employed to quantify and characterize inter-individual differences in human brain function. Head motion remains a significant concern in the accurate determination of resting-state fMRI based assessments of the connectome, including those based on graph theoretical analysis (e.g., motion can increase local efficiency, while decreasing global efficiency and small-worldness. This study provides a comprehensive examination of motion correction strategies on the relationship between motion and commonly used topological parameters. At the individual-level, we evaluated different models of head motion regression and scrubbing, as well as the potential benefits of using partial correlation (estimated via graphical lasso instead of full correlation. At the group-level, we investigated the utility of regression of motion and mean intrinsic functional connectivity before topological parameters calculation and/or after. Consistent with prior findings, none of the explicit motion-correction approaches at individual-level were able to remove motion relationships for topological parameters. Global signal regression (GSR emerged as an effective means of mitigating relationships between motion and topological parameters; though at the risk of altering the connectivity structure and topological hub distributions when higher densities graphs are employed (e.g., > 6%. Group-level analysis correction for motion was once again found to be a crucial step. Finally, similar to recent work, we found a constellation of findings suggestive of the possibility that some of the motion-relationships detected may reflect neural or trait signatures of motion, rather than simply motion-induced artifact.

  15. Trade-offs between robustness and small-world effect in complex networks

    Science.gov (United States)

    Peng, Guan-Sheng; Tan, Suo-Yi; Wu, Jun; Holme, Petter

    2016-11-01

    Robustness and small-world effect are two crucial structural features of complex networks and have attracted increasing attention. However, little is known about the relation between them. Here we demonstrate that, there is a conflicting relation between robustness and small-world effect for a given degree sequence. We suggest that the robustness-oriented optimization will weaken the small-world effect and vice versa. Then, we propose a multi-objective trade-off optimization model and develop a heuristic algorithm to obtain the optimal trade-off topology for robustness and small-world effect. We show that the optimal network topology exhibits a pronounced core-periphery structure and investigate the structural properties of the optimized networks in detail.

  16. Avoiding the "It's a Small World" Effect: A Lesson Plan to Explore Diversity

    Science.gov (United States)

    Endacott, Jason L.; Bowles, Freddie A.

    2013-01-01

    Classroom instruction about other cultures all too often resembles the Disney version of "It's a Small World" with Fantasyland-like cultural stereotypes, ceremonial activities, and traditional dress that can lead to serious

  17. Transition from local to global phase synchrony in small world neural network and its possible implications for epilepsy

    CERN Document Server

    Percha, B; Zochowski, M; Percha, Bethany; Dzakpasu, Rhonda; Zochowski, Micha{\\l} \\.

    2004-01-01

    Temporal correlations in the brain are thought to have very dichotomic roles. On one hand they are ubiquitously present in the healthy brain and are thought to underlie feature binding during information processing. On the other hand large scale synchronization is an underlying mechanism of epileptic seizures. In this paper we show a possible mechanism of transition to pathological coherence underlying seizure generation. We show that properties of phase synchronization in the 2-D lattice of non-identical coupled Hindmarsh-Rose neurons change radically depending on the connectivity structure. We modify the connectivity using the small world network paradigm and measure properties of phase synchronization using previously developed measure based on assessment of the distributions of relative interspike intervals. We show that the phase synchronization undergoes a dramatic change as a function of locality of network connections from local coherence strongly dependent on the distance between two neurons to globa...

  18. Altered small-world anatomical networks in Apolipoprotein-E4 (ApoE4) carriers using MRI.

    Science.gov (United States)

    Goryawala, Mohammed; Zhou, Qi; Duara, Ranjan; Loewenstein, David; Cabrerizo, Mercedes; Barker, Warren; Adjouadi, Malek

    2014-01-01

    Apolipoprotein E (ApoE) gene and primarily its allele e4 have been identified as a risk factor for Alzheimer's disease (AD). The prevalence of the gene in 25-30% in the population makes it essential to estimate its role in neuroregulation and its impact on distributed brain networks. In this study, we provide computational neuroanatomy based interpretation of large-scale and small-world cortical networks in cognitive normal (CN) subjects with differing Apolipoprotein-E4 (ApoE4) gene expression. We estimated large-scale anatomical networks from cortical thickness measurements derived from magnetic resonance imaging in 147 CN subjects explored in relation to ApoE4 genotype (e4+ carriers (n=41) versus e4- non-carriers (n=106)). Brain networks were constructed by thresholding cortical thickness correlation matrices of 68 bilateral regions of the brain analyzed using well-established graph theoretical approaches. Compared to ApoE4 non-carriers, carriers showed increased interregional correlation coefficients in regions like precentral, superior frontal and inferior temporal regions. Interestingly most of the altered connections were intra-hemispheric limited primarily to the right hemisphere. Furthermore, ApoE4 carriers demonstrated abnormal small-world architecture in the cortical networks with increased clustering coefficient and path lengths as compared to non-carrier, suggesting a less optimal topological organization. Additionally non-carriers demonstrated higher betweenness in regions such as middle temporal, para-hippocampal gyrus, posterior cingulate and insula of the default mode network (DMN), also seen in subjects with AD and mild cognitive impairment (MCI). The results suggest that the complex morphological cortical connectivity patterns are altered in ApoE4 carriers as compared to non-carriers, providing evidence for disruption of integrity in large-scale anatomical brain networks.

  19. Small-world to fractal transition in complex networks: a renormalization group approach.

    Science.gov (United States)

    Rozenfeld, Hernán D; Song, Chaoming; Makse, Hernán A

    2010-01-15

    We show that renormalization group (RG) theory applied to complex networks is useful to classify network topologies into universality classes in the space of configurations. The RG flow readily identifies a small-world-fractal transition by finding (i) a trivial stable fixed point of a complete graph, (ii) a nontrivial point of a pure fractal topology that is stable or unstable according to the amount of long-range links in the network, and (iii) another stable point of a fractal with shortcuts that exist exactly at the small-world-fractal transition. As a collateral, the RG technique explains the coexistence of the seemingly contradicting fractal and small-world phases and allows us to extract information on the distribution of shortcuts in real-world networks, a problem of importance for information flow in the system.

  20. Brief Communication: Seasonality of diet composition is related to brain size in New World Monkeys.

    Science.gov (United States)

    van Woerden, Janneke T; van Schaik, Carel P; Isler, Karin

    2014-08-01

    New World monkeys exhibit a more pronounced variability in encephalization than other primate taxa. In this comparative study, we tested two current hypotheses on brain size evolution, the Expensive Brain hypothesis and the Cognitive Buffer hypothesis, in a sample of 21 platyrrhine species. A high degree of habitat seasonality may impose an energetic constraint on brain size evolution if it leads to a high variation in caloric intake over time, as predicted by the Expensive Brain Hypothesis. However, simultaneously it may also provide the opportunity to reap the fitness benefits of increased cognitive abilities, which enable the exploitation of high-quality food resources even during periods of scarcity, as predicted by the Cognitive Buffer hypothesis. By examining the effects of both habitat seasonality and the variation in monthly diet composition across species, we found support for both hypotheses, confirming previous results for catarrhine primates and lemurs. These findings are in accordance with an energetic and ecological view of brain size evolution.

  1. Strategic Lean Organizational Design: Towards Lean World-Small World Configurations through Discrete Dynamic Organizational Motifs

    Directory of Open Access Journals (Sweden)

    Javier Villalba-Diez

    2016-01-01

    Full Text Available Organizations face strong international competition in the global market arena in achieving strategic goals such as high quality of product or service at lower cost while increasing their ability to respond quickly to requirements of the market. These challenges concern strategically designing organizations that can meet global challenges and specialize locally to meet performance constraints. After introducing the concept of organizational functional and structural motifs as small organizational building block, our findings suggest the hypothesis that a strategic organizational design (SOD approach to meet these challenges involves maximizing the number and diversity of functional motifs, while minimizing the repertoire of structural motifs. By detecting characteristic structural motifs, we provide organizational leaders with specific Lean SOD solutions with which to meet local and global challenges simultaneously. As a matter of application, we show the implementation of such an SOD approach in nine US hospitals that form one large health care holding.

  2. SWER: small world-based efficient routing for wireless sensor networks with mobile sinks

    Institute of Scientific and Technical Information of China (English)

    Xuejun LIU; Jihong GUAN; Guangwei BAI; Haiming LU

    2009-01-01

    The interest in small-world network has high-lighted the applicability of both the graph theory and the scaling theory to the analysis of network systems. In this pa-per, we introduce a new routing protocol, small world-based efficient routing (SWER), dedicated to supporting sink mo-bility and small transfers. The method is based on the con-cept of the small worlds where the addition of a small num-ber of long-range links in highly clustered networks results in significant reduction in the average path length. Based on the characteristic of sensor networks, a cluster-based small world network is presented, and an analytical model is de-veloped to analyze the expected path length. SWER adopts a simple and effective routing strategy to forward data to the mobile sink in a small transfer scene and avoid expensive mechanisms to construct a high quality route. We also study the routing scheme and analyze the expected path length in the case where every node is aware of the existence ofp long-range links. In addition, we develop a hierarchical mech-anism in which the mobile sink only transmits its location information to the cluster heads when it enters a new cluster. Thus we also avoid expensive cost to flood the location of the mobile sink to the whole network.

  3. "The Most Famous Brain in the World" Performance and Pedagogy on an Amnesiac's Brain

    Science.gov (United States)

    Sweaney, Katherine W.

    2012-01-01

    Project H.M. was just the sort of thing one might expect the Internet to latch onto: it was a live streaming video of a frozen human brain being slowly sliced apart. Users who clicked the link on Twitter or Facebook between the 2nd and 4th of December 2009 were immediately confronted with a close-up shot of the brain's interior, which was…

  4. Disrupted small world networks in patients without overt hepatic encephalopathy: A resting state fMRI study

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Long Jiang, E-mail: kevinzhlj@163.com [Department of Medical Imaging, Jinling Hospital, Medical School of Nanjing University, Nanjing, Jiangsu 210002 (China); Zheng, Gang [Department of Medical Imaging, Jinling Hospital, Medical School of Nanjing University, Nanjing, Jiangsu 210002 (China); College of Civil Aviation, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu 210016 (China); Zhang, Liping [College of Natural Science, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu 210016 (China); Zhong, Jianhui [Department of Biomedical Engineering, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Li, Qiang [College of Natural Science, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu 210016 (China); Zhao, Tie Zhu [Department of Medical Imaging, Jinling Hospital, Medical School of Nanjing University, Nanjing, Jiangsu 210002 (China); College of Civil Aviation, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu 210016 (China); Lu, Guang Ming, E-mail: cjr.luguangming@vip.163.com [Department of Medical Imaging, Jinling Hospital, Medical School of Nanjing University, Nanjing, Jiangsu 210002 (China)

    2014-10-15

    Purpose: To explore changes in functional connectivity and topological organization of brain functional networks in cirrhotic patients with minimal hepatic encephalopathy (MHE) and non hepatic encephalopathy (nonHE) and their relationship with clinical markers. Materials and methods: Resting-state functional MR imaging was acquired in 22 MHE, 29 nonHE patients and 33 healthy controls. Functional connectivity networks were obtained by computing temporal correlations between any pairs of 90 cortical and subcortical regions. Graph analysis measures were quantitatively assessed for each subject. One-way analysis of covariance was applied to identify statistical differences of functional connectivity and network parameters among three groups. Correlations between clinical markers, such as Child–Pugh scores, venous blood ammonia level, and number connection test type A (NCT-A)/digit symbol test (DST) scores, and connectivity/graph metrics were calculated. Results: Thirty functional connectivities represented by edges were found to be abnormal (P < 0.05, FDR corrected) in cirrhotic patients, in which 16 edges (53.3%) were related with sub-cortical regions. MHE patients showed abnormal small-world attributes in the functional connectivity networks. Cirrhotic patients had significantly reduced nodal degree in 8 cortical regions and increased nodal centrality in 3 cortical regions. Twenty edges were correlated with either NCT-A or DST scores, in which 13 edges were related with sub-cortical regions. No correlation was found between Child–Pugh scores and graph theoretical measures in cirrhotic patients. Conclusion: Disturbances of brain functional connectivity and small world property loss are associated with neurocognitive impairment of cirrhotic patients. Reorganization of brain network occurred during disease progression from nonHE to MHE.

  5. Small World Properties Generated by a New Algorithm Under Same Degree of All Nodes

    Institute of Scientific and Technical Information of China (English)

    LI Yong; FANG Jin-Qing; LIU Qiang; LIANG Yong

    2006-01-01

    Based on the model of the same degree of all nodes we proposed before, a new algorithm, the so-called"spread all over vertices" (SAV) algorithm, is proposed for generating small-world properties from a regular ring lattices.During randomly rewiring connections the SAV is used to keep the unchanged number of links. Comparing the SAV algorithm with the Watts-Strogatz model and the "spread all over boundaries" algorithm, three methods can have the same topological properties of the small world networks. These results offer diverse formation of small world networks.It is helpful to the research of some applications for dynamics of mutual oscillator inside nodes and interacting automata associated with networks.

  6. Fractal and Small-World Networks Formed by Self-Organized Critical Dynamics

    Science.gov (United States)

    Watanabe, Akitomo; Mizutaka, Shogo; Yakubo, Kousuke

    2015-11-01

    We propose a dynamical model in which a network structure evolves in a self-organized critical (SOC) manner and explain a possible origin of the emergence of fractal and small-world networks. Our model combines a network growth and its decay by failures of nodes. The decay mechanism reflects the instability of large functional networks against cascading overload failures. It is demonstrated that the dynamical system surely exhibits SOC characteristics, such as power-law forms of the avalanche size distribution, the cluster size distribution, and the distribution of the time interval between intermittent avalanches. During the network evolution, fractal networks are spontaneously generated when networks experience critical cascades of failures that lead to a percolation transition. In contrast, networks far from criticality have small-world structures. We also observe the crossover behavior from fractal to small-world structure in the network evolution.

  7. Fractal and Small-World Networks Formed by Self-Organized Critical Dynamics

    CERN Document Server

    Watanabe, Akitomo; Yakubo, Kousuke

    2015-01-01

    We propose a dynamical model in which a network structure evolves in a self-organized critical (SOC) manner and explain a possible origin of the emergence of fractal and small-world networks. Our model combines a network growth and its decay by failures of nodes. The decay mechanism reflects the instability of large functional networks against cascading overload failures. It is demonstrated that the dynamical system surely exhibits SOC characteristics, such as power-law forms of the avalanche size distribution, the cluster size distribution, and the distribution of the time interval between intermittent avalanches. During the network evolution, fractal networks are spontaneously generated when networks experience critical cascades of failures that lead to a percolation transition. In contrast, networks far from criticality have small-world structures. We also observe the crossover behavior from fractal to small-world structure in the network evolution.

  8. Growing Small-World Networks Based on a Modified BA Model

    Institute of Scientific and Technical Information of China (English)

    XU Xin-Ping; LIU Feng; LI Wei

    2006-01-01

    @@ We modify the (Barabási-Albert) BA model for the evolution of small-world networks. It is introduced as a modified BA model in which all the edges connected to the new node are made locally to the old node and its nearest neighbours. It is found that this model can produce small-world networks with power-law degree distributions. Properties of our model, including the degree distribution, clustering, average path length and degree correlation coefficient are compared with that of the BA model. Since most real networks are both scale free and small-world networks, our model may provide a satisfactory description for empirical characteristics of real networks.

  9. Achieving Small World Properties using Bio-Inspired Techniques in Wireless Networks

    CERN Document Server

    Agarwal, Rachit; Gauthier, Vincent; Becker, Monique; Yeo, Chai Kiat; Lee, Bu Sung

    2011-01-01

    Self-Organization properties of the nodes play an important role in an autonomous wireless sensor environment in achieving network wide characteristics. Self-Organization can be used to achieve small world characteristics in a network. In real networks, however, where there is non-uniform distribution of nodes and overall connectivity of the network is less, achieving small world properties while increasing connectivity must be studied. We believe that network connectivity can be increased and small world properties can be achieved with the help of beamforming, biologically inspired algorithms and using local information. Most of the researches performed in direction of achieving above mentioned goals in wireless networks assume knowledge of network with either heterogeneous or hybrid uniform deployment. We propose that without the knowledge of the global environment or introduction of any special features in the network, we can achieve our goal with the help of inspirations from the nature in a non-uniform n...

  10. Synchronizability of Small-World Networks Generated from a Two-Dimensional Kleinberg Model

    Directory of Open Access Journals (Sweden)

    Yi Zhao

    2013-01-01

    Full Text Available This paper investigates the synchronizability of small-world networks generated from a two-dimensional Kleinberg model, which is more general than NW small-world network. The three parameters of the Kleinberg model, namely, the distance of neighbors, the number of edge-adding, and the edge-adding probability, are analyzed for their impacts on its synchronizability and average path length. It can be deduced that the synchronizability becomes stronger as the edge-adding probability increases, and the increasing edge-adding probability could make the average path length of the Kleinberg small-world network go smaller. Moreover, larger distance among neighbors and more edges to be added could play positive roles in enhancing the synchronizability of the Kleinberg model. The lorentz oscillators are employed to verify the conclusions numerically.

  11. 2007 International Brain Mapping and Intraoperative Surgical Planning Society’s (IBMISPS) Annual World Congress

    Science.gov (United States)

    2008-02-01

    Empowered Functional Brain Imaging Cochair: Jeffrey David LEWINE Executive Director, Alexian Center for Brain Research Executive Director, Illinois...local thermal treatment improve efficacy of treatment6 Personalized targeted gene therapy Kateb B et al. Slide 9/24 Carbon Nanotubes Kateb B et al...genotype- phenotype correlations explore known severe single gene disorders in small case series. “The Child is the father of the Man.” William

  12. Cushing and the treatment of brain wounds during World War I.

    Science.gov (United States)

    Carey, Michael E

    2011-06-01

    Harvey Cushing, perhaps the most important founder of American neurosurgery, was an Army neurosurgeon in France from 1917 to 1918. Over a 3-month period in 1917 he and his team operated on 133 soldiers with a brain wound. The operative mortality rate for their last 45 patients was 29%, considerably lower than the usual postoperative mortality rate of approximately 50% for those with a brain wound. This accomplishment was lauded at the time and eventually, for some, it was Cushing who was responsible for lowering the postoperative mortality rate of brain wounds during World War I. As the decades passed he was eventually credited as the "originator of brain wound care." This report shows that these attributions are misplaced. Cushing merely followed the enlightened surgical precepts of the time developed by Continental (European) surgeons. It also examines Cushing's writings to ascertain how these misperceptions concerning his originality might have been generated.

  13. Small-world Characteristics of EEG Patterns in Post-Anoxic Encephalopathy

    Directory of Open Access Journals (Sweden)

    Martijn eBeudel

    2014-06-01

    Full Text Available Post-Anoxic Encephalopathy (PAE has a heterogenous outcome which is difficult to predict. At present, it is possible to predict poor outcome using somatosensory evoked potentials (SSEP in only a minority of the patients at an early stage. In addition, it remains difficult to predict good outcome at an early stage. Network architecture, as can be quantified with continuous electroencephalography (cEEG, may serve as a candidate measure for predicting neurological outcome. Here we explore whether cEEG monitoring can be used to detect the integrity of neural network architecture in patients with PAE after cardiac arrest. From 56 patients with PAE treated with mild therapeutic hypothermia (MTH, 19-channel cEEG data was recorded starting as soon as possible after cardiac arrest. Adjacency matrices of shared frequencies between 1 and 25 Hz of the EEG channels were obtained using Fourier transformations. Number of network nodes and connections, clustering coefficient (C, average path length (L and small-world index (SWI were derived. Outcome was quantified by the best Cerebral Performance Category (CPC-score within 6 months. Compared to non-survivors, survivors showed significantly more nodes and connections. L was significantly higher and C and SWI were significantly lower in the survivor group than in the non-survivor group. The number of nodes, connections and the L negatively correlated with the CPC-score. C and SWI correlated positively with the CPC-score. The combination of number of nodes, connections, C and L showed the most significant difference and correlation between survivors and non-survivors and CPC-score. Our data might implicate that non-survivors have insufficient distribution and differentiation of neural activity for regaining normal brain function. These network differences, already present during hypothermia, might be further developed as early prognostic markers. The predictive values are however still inferior to current practice

  14. Self-Organization of Wireless Ad Hoc Networks as Small Worlds Using Long Range Directional Beams

    CERN Document Server

    Banerjee, Abhik; Gauthier, Vincent; Yeo, Chai Kiat; Afifi, Hossam; Lee, Bu Sung

    2011-01-01

    We study how long range directional beams can be used for self-organization of a wireless network to exhibit small world properties. Using simulation results for randomized beamforming as a guideline, we identify crucial design issues for algorithm design. Subsequently, we propose an algorithm for deterministic creation of small worlds. We define a new centrality measure that estimates the structural importance of nodes based on traffic flow in the network, which is used to identify the optimum nodes for beamforming. This results in significant reduction in path length while maintaining connectivity.

  15. Investigation of the forest-fire model on a small-world network.

    Science.gov (United States)

    Graham, I; Matthai, C C

    2003-09-01

    It is shown that the forest-fire model of Bak et al. run on a square lattice network with additional long-range interactions in the spirit of a small-world network results in a scale-free system reminiscent of self-organized criticality without recourse to fine tuning. As the number of these long-range interactions is increased, the cluster size distribution exponent is found to decrease in magnitude as the small-world regime is entered, indicating a change in its universality class. It is suggested that such a model could have applicability in the study of disease spreading in human populations.

  16. Influence of Different Connectivity Topologies in Small World Networks Modeling Earthquakes

    Institute of Scientific and Technical Information of China (English)

    LINMin; CHENTian-Lun

    2004-01-01

    We introduce the Olami-Feder-Christensen (OFC) model on a square lattice with some "rewired" longrange connections having the properties of small world networks. We find that our model displays the power-law behavior, and connectivity topologies are very important to model's avalanche dynamical behaviors. Our model has some behaviors different from the OFC model on a small world network with "added" long-range connections in our previous work [LIN Min, ZHAO Xiao-Wei, and CHEN Tian-Lun, Commun. Theor. Phys. (Beijing, China) 41 (2004) 557.].

  17. Influence of Different Connectivity Topologies in Small World Networks Modeling Earthquakes

    Institute of Scientific and Technical Information of China (English)

    LIN Min; CHEN Tian-Lun

    2004-01-01

    We introduce the Olami-Feder-Christensen (OFC) model on a squarelattice with some "rewired" long-range connections having the properties of small world networks. We find that our model displays the power-law behavior,and connectivity topologies are very important to model's avalanche dynamical behaviors. Our model has some behaviorsdifferent from the OFC model on a small world network with "added" long-range connections in our previous work [LINMin, ZHAO Xiao-Wei, and CHEN Tian-Lun, Commun. Theor. Phys. (Beijing, China) 41 (2004) 557.].

  18. Potts model on directed small-world Voronoi-Delaunay lattices

    Science.gov (United States)

    Marques, R. M.; Lima, F. W. S.; Costa Filho, Raimundo N.

    2016-06-01

    The critical properties of the Potts model with q = 3 and 4 states in two-dimensions on directed small-world Voronoi-Delaunay random lattices with quenched connectivity disorder are investigated. This disordered system is simulated by applying the Monte Carlo update heat bath algorithm. The Potts model on these directed small-world random lattices presents in fact a second-order phase transition with new critical exponents for q = 3 and value of the rewiring probability p = 0.01, but for q = 4 the system exhibits only a first-order phase transition independent of p (0 < p < 1).

  19. Evolutionary snowdrift game on heterogeneous Newman-Watts small-world network

    Institute of Scientific and Technical Information of China (English)

    Yang Han-Xin; Gao Kun; Han Xiao-Pu; Wang Bing-Hong

    2008-01-01

    We study the evolutionary snowdrift game in a heterogeneous Newman-Watts small-world network. The hetero-geneity of the network is controlled by the number of hubs. It is found that the moderate heterogeneity of the network can promote the cooperation best. Besides, we study how the hubs affect the evolution of cooperative behaviours of the heterogeneous Newman-Watts small-world network. Simulation results show that both the initial states of hubs and the connections between hubs can play an important role. Our work gives a further insight into the effect of hubs on the heterogeneous networks.

  20. A small-world-based population encoding model of the primary visual cortex.

    Science.gov (United States)

    Shi, Li; Niu, Xiaoke; Wan, Hong; Shang, Zhigang; Wang, Zhizhong

    2015-06-01

    A wide range of evidence has shown that information encoding performed by the visual cortex involves complex activities of neuronal populations. However, the effects of the neuronal connectivity structure on the population's encoding performance remain poorly understood. In this paper, a small-world-based population encoding model of the primary visual cortex (V1) is established on the basis of the generalized linear model (GLM) to describe the computation of the neuronal population. The model mainly consists of three sets of filters, including a spatiotemporal stimulus filter, a post-spike history filter, and a set of coupled filters with the coupling neurons organizing as a small-world network. The parameters of the model were fitted with neuronal data of the rat V1 recorded with a micro-electrode array. Compared to the traditional GLM, without considering the small-world structure of the neuronal population, the proposed model was proved to produce more accurate spiking response to grating stimuli and enhance the capability of the neuronal population to carry information. The comparison results proved the validity of the proposed model and further suggest the role of small-world structure in the encoding performance of local populations in V1, which provides new insights for understanding encoding mechanisms of a small scale population in visual system.

  1. Advances in Bevacizumab Therapy for Non-small Cell Lung Cancer 
with Brain Metastases

    Directory of Open Access Journals (Sweden)

    Liyan QU

    2016-08-01

    Full Text Available Brain metastases are frequently encountered in patients with non-small cell lung cancer (NSCLC and are a significant cause of morbidity and mortality. Antiangiogenesis therapy plays a major role in the management of brain metastases in lung cancer. Bevacizumab have become the novel method for the treatment of lung cancer with brain metastases beyond the whole brain radiation therapy, stereotactic radiosurgery and chemotherapy. Recently, more and more studies and trials laid emphasis on the bevacizumab for NSCLC with brain metastases treatment. The key point is the efficacy and safety. In this review, bevacizumab therapy of NSCLC with brain metastases were summarized.

  2. Effect of intermodular connection on fast sparse synchronization in clustered small-world neural networks

    Science.gov (United States)

    Kim, Sang-Yoon; Lim, Woochang

    2015-11-01

    We consider a clustered network with small-world subnetworks of inhibitory fast spiking interneurons and investigate the effect of intermodular connection on the emergence of fast sparsely synchronized rhythms by varying both the intermodular coupling strength Jinter and the average number of intermodular links per interneuron Msyn(inter ). In contrast to the case of nonclustered networks, two kinds of sparsely synchronized states such as modular and global synchronization are found. For the case of modular sparse synchronization, the population behavior reveals the modular structure, because the intramodular dynamics of subnetworks make some mismatching. On the other hand, in the case of global sparse synchronization, the population behavior is globally identical, independently of the cluster structure, because the intramodular dynamics of subnetworks make perfect matching. We introduce a realistic cross-correlation modularity measure, representing the matching degree between the instantaneous subpopulation spike rates of the subnetworks, and examine whether the sparse synchronization is global or modular. Depending on its magnitude, the intermodular coupling strength Jinter seems to play "dual" roles for the pacing between spikes in each subnetwork. For large Jinter, due to strong inhibition it plays a destructive role to "spoil" the pacing between spikes, while for small Jinter it plays a constructive role to "favor" the pacing between spikes. Through competition between the constructive and the destructive roles of Jinter, there exists an intermediate optimal Jinter at which the pacing degree between spikes becomes maximal. In contrast, the average number of intermodular links per interneuron Msyn(inter ) seems to play a role just to favor the pacing between spikes. With increasing Msyn(inter ), the pacing degree between spikes increases monotonically thanks to the increase in the degree of effectiveness of global communication between spikes. Furthermore, we

  3. Best of both worlds: promise of combining brain stimulation and brain connectome

    OpenAIRE

    Caroline Di Bernardi Luft; Ernesto ePereda; Michael eBanissy; Joydeep eBhattacharya

    2014-01-01

    Transcranial current brain stimulation (tCS) is becoming increasingly popular as a non-pharmacological non-invasive neuromodulatory method that alters cortical excitability by applying weak electrical currents to the scalp via a pair of electrodes. Most applications of this technique have focused on enhancing motor and learning skills, as well as a therapeutic agent in neurological and psychiatric disorders. In these applications, similarly to lesion studies, tCS was used to provide a causal ...

  4. Best of both worlds: Promise of combining brain stimulation and brain connectome

    Directory of Open Access Journals (Sweden)

    Caroline Di Bernardi Luft

    2014-07-01

    Full Text Available Transcranial current brain stimulation (tCS is becoming increasingly popular as a non-pharmacological non-invasive neuromodulatory method that alters cortical excitability by applying weak electrical currents to the scalp via a pair of electrodes. Most applications of this technique have focused on enhancing motor and learning skills, as well as a therapeutic agent in neurological and psychiatric disorders. In these applications, similarly to lesion studies, tCS was used to provide a causal link between a function or behaviour and a specific brain region (e.g., primary motor cortex. Nonetheless, complex cognitive functions are known to rely on functionally connected multitude of brain regions with dynamically changing patterns of information flow rather than on isolated areas, which are most commonly targeted in typical tCS experiments. In this review article, we argue in favour of combining tCS method with other neuroimaging techniques (e.g. fMRI, EEG and by employing state-of-the-art connectivity data analysis techniques (e.g. graph theory to obtain a deeper understanding of the underlying spatiotemporal dynamics of functional connectivity patterns and cognitive performance. Finally, we discuss the possibilities of these combined techniques to investigate the neural correlates of human creativity and to enhance creativity.

  5. Damage spreading in spatial and small-world random boolean networks

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Qiming [Los Alamos National Laboratory; Teuscher, Christof [Los Alamos National Laboratory

    2008-01-01

    Random Boolean Networks (RBNs) are often used as generic models for certain dynamics of complex systems, ranging from social networks, neural networks, to gene or protein interaction networks. Traditionally, RBNs are interconnected randomly and without considering any spatial arrangement of the links and nodes. However, most real-world networks are spatially extended and arranged with regular, small-world, or other non-random connections. Here we explore the RBN network topology between extreme local connections, random small-world, and random networks, and study the damage spreading with small perturbations. We find that spatially local connections change the scaling of the relevant component at very low connectivities ({bar K} << 1) and that the critical connectivity of stability K{sub s} changes compared to random networks. At higher {bar K}, this scaling remains unchanged. We also show that the relevant component of spatially local networks scales with a power-law as the system size N increases, but with a different exponent for local and small-world networks. The scaling behaviors are obtained by finite-size scaling. We further investigate the wiring cost of the networks. From an engineering perspective, our new findings provide the key trade-offs between damage spreading (robustness), the network wiring cost, and the network's communication characteristics.

  6. Spatial and Temporal Behaviors in a Modified Evolution Model Based on Small World Network

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiao-Wei; ZHOU Li-Ming; CHEN Tian-Lun

    2004-01-01

    In this paper, we introduce a new modified evolution model on a small world network. In our model,the spatial and temporal correlations and the spatial-temporal evolve pattern of mutating nodes exhibit some particular behaviors different from those of the original BS evolution model. More importantly, these behaviors will change with φ, the density of short paths in our network.

  7. A Modified Earthquake Model of Self-Organized Criticality on Small World Networks

    Institute of Scientific and Technical Information of China (English)

    LIN Min; ZHAO Xiao-Wei; CHEN Tian-Lun

    2004-01-01

    A modified Olami Feder-Christensen model of self-organized criticality on a square lattice with the properties of small world networks has been studied.We find that our model displays power-law behavior and the exponent τ of the model depends on φ,the density of long-range connections in our network.

  8. Small worlds and semantic network growth in typical and late talkers.

    Science.gov (United States)

    Beckage, Nicole; Smith, Linda; Hills, Thomas

    2011-05-11

    Network analysis has demonstrated that systems ranging from social networks to electric power grids often involve a small world structure-with local clustering but global ac cess. Critically, small world structure has also been shown to characterize adult human semantic networks. Moreover, the connectivity pattern of these mature networks is consistent with lexical growth processes in which children add new words to their vocabulary based on the structure of the language-learning environment. However, thus far, there is no direct evidence that a child's individual semantic network structure is associated with their early language learning. Here we show that, while typically developing children's early networks show small world structure as early as 15 months and with as few as 55 words, children with language delay (late talkers) have this structure to a smaller degree. This implicates a maladaptive bias in word acquisition for late talkers, potentially indicating a preference for "oddball" words. The findings provide the first evidence of a link between small-world connectivity and lexical development in individual children.

  9. Small worlds and semantic network growth in typical and late talkers.

    Directory of Open Access Journals (Sweden)

    Nicole Beckage

    Full Text Available Network analysis has demonstrated that systems ranging from social networks to electric power grids often involve a small world structure-with local clustering but global ac cess. Critically, small world structure has also been shown to characterize adult human semantic networks. Moreover, the connectivity pattern of these mature networks is consistent with lexical growth processes in which children add new words to their vocabulary based on the structure of the language-learning environment. However, thus far, there is no direct evidence that a child's individual semantic network structure is associated with their early language learning. Here we show that, while typically developing children's early networks show small world structure as early as 15 months and with as few as 55 words, children with language delay (late talkers have this structure to a smaller degree. This implicates a maladaptive bias in word acquisition for late talkers, potentially indicating a preference for "oddball" words. The findings provide the first evidence of a link between small-world connectivity and lexical development in individual children.

  10. Big Policies and a Small World: An Analysis of Policy Problems and Solutions in Physical Education

    Science.gov (United States)

    Penney, Dawn

    2017-01-01

    This paper uses Ball's [1998. Big policies/small world: An introduction to international perspectives in education policy. "Comparative Education," 34(2), 119-130] policy analysis and Bernstein's [1990. "The structuring of pedagogic discourse. Volume IV class, codes and control". London: Routledge; 2000, "Pedagogy,…

  11. Damage Spreading in Spatial and Small-world Random Boolean Networks

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Qiming [Fermilab; Teuscher, Christof [Portland State U.

    2014-02-18

    The study of the response of complex dynamical social, biological, or technological networks to external perturbations has numerous applications. Random Boolean Networks (RBNs) are commonly used a simple generic model for certain dynamics of complex systems. Traditionally, RBNs are interconnected randomly and without considering any spatial extension and arrangement of the links and nodes. However, most real-world networks are spatially extended and arranged with regular, power-law, small-world, or other non-random connections. Here we explore the RBN network topology between extreme local connections, random small-world, and pure random networks, and study the damage spreading with small perturbations. We find that spatially local connections change the scaling of the relevant component at very low connectivities ($\\bar{K} \\ll 1$) and that the critical connectivity of stability $K_s$ changes compared to random networks. At higher $\\bar{K}$, this scaling remains unchanged. We also show that the relevant component of spatially local networks scales with a power-law as the system size N increases, but with a different exponent for local and small-world networks. The scaling behaviors are obtained by finite-size scaling. We further investigate the wiring cost of the networks. From an engineering perspective, our new findings provide the key design trade-offs between damage spreading (robustness), the network's wiring cost, and the network's communication characteristics.

  12. Dynamics of organizational rumor communication on connecting multi-small-world networks

    Institute of Scientific and Technical Information of China (English)

    Xing Qi-Bin; Zhang Yuan-Biao; Liang Zhi-Ning; ZhangFan

    2011-01-01

    We study the dynamics of an epidemic-like model for the spread of a rumor on a connecting multi-small-world-network (CM-SWN) model,which represents organizational communication in the real world.It has been shown that this model exhibits a transition between regimes of localization and propagation at a finite value of network randomness.Here,by numerical means,we perform a quantitative characterization of the evolution in the three groups under two evolution rules,namely the conformity and obeying principles.The variant of a dynamic CM-SWN,where the quenched disorder of small-world networks is replaced by randomly changing connections between individuals in a single network and stable connection by star nodes between networks,is also analysed in detail and compared with a mean-field approximation.

  13. Inquiring the Potential of Evoking Small-World Properties for Self-Organizing Communication Networks

    CERN Document Server

    Brust, Matthias R; Ribeiro, Carlos H C

    2007-01-01

    Mobile multi-hop ad hoc networks allow establishing local groups of communicating devices in a self-organizing way. However, in a global setting such networks fail to work properly due to network partitioning. Providing that devices are capable of communicating both locally-e.g. using Wi-Fi or Bluetooth-and additionally also with arbitrary remote devices-e.g. using GSM/UMTS links-the objective is to find efficient ways of inter-linking multiple network partitions. Tackling this problem of topology control, we focus on the class of small-world networks that obey two distinguishing characteristics: they have a strong local clustering while still retaining a small average distance between two nodes. This paper reports on results gained investigating the question if small-world properties are indicative for an efficient link management in multiple multi-hop ad hoc network partitions.

  14. BRAIN INJURY BIOMECHANICS IN REAL WORLD VEHICLE ACCIDENT USING MATHEMATICAL MODELS

    Institute of Scientific and Technical Information of China (English)

    YANG Jikuang; XU Wei; OTTE Dietmar

    2008-01-01

    This paper aims at investigating brain injury mechanisms and predicting head injuries in real world accidents. For this purpose, a 3D human head finite element model (HBM-head) was developed based on head-brain anatomy. The HBM head model was validated with two experimental tests. Then the head finite element(FE) model and a multi-body system (MBS) model were used to carry out reconstructions of real world vehicle-pedestrian accidents and brain injuries. The MBS models were used for calculating the head impact conditions in vehicle impacts. The HBM-head model was used for calculating the injury related physical parameters, such as intracranial pressure, stress, and strain. The calculated intracranial pressure and strain distribution were correlated with the injury outcomes observed from accidents. It is shown that this model can predict the intracranial biomechanical response and calculate the injury related physical parameters. The head FE model has good biofidelity and will be a valuable tool for the study of injury mechanisms and the tolerance level of the brain.

  15. Small-world topology of functional connectivity in randomly connected dynamical systems.

    Science.gov (United States)

    Hlinka, J; Hartman, D; Paluš, M

    2012-09-01

    Characterization of real-world complex systems increasingly involves the study of their topological structure using graph theory. Among global network properties, small-world property, consisting in existence of relatively short paths together with high clustering of the network, is one of the most discussed and studied. When dealing with coupled dynamical systems, links among units of the system are commonly quantified by a measure of pairwise statistical dependence of observed time series (functional connectivity). We argue that the functional connectivity approach leads to upwardly biased estimates of small-world characteristics (with respect to commonly used random graph models) due to partial transitivity of the accepted functional connectivity measures such as the correlation coefficient. In particular, this may lead to observation of small-world characteristics in connectivity graphs estimated from generic randomly connected dynamical systems. The ubiquity and robustness of the phenomenon are documented by an extensive parameter study of its manifestation in a multivariate linear autoregressive process, with discussion of the potential relevance for nonlinear processes and measures.

  16. Systemic Chemotherapy for Progression of Brain Metastases in Extensive-Stage Small Cell Lung Cancer

    Directory of Open Access Journals (Sweden)

    Nagla Abdel Karim

    2015-01-01

    Full Text Available Lung cancer is the most common cause of cancer related mortality in men and women. Approximately 15% of lung cancers are small cell type. Chemotherapy and radiation are the mainstay treatments. Currently, the standard chemotherapy regimen includes platinum/etoposide. For extensive small cell lung cancer, irinotecan and cisplatin have also been used. Patients with relapsed small cell lung cancer have a very poor prognosis, and the morbidity increases with brain metastases. Approximately 10%–14% of small cell lung cancer patients exhibit brain metastases at the time of diagnosis, which increases to 50%–80% as the disease progresses. Mean survival with brain metastases is reported to be less than six months, thus calling for improved regimens. Here we present a case series of patients treated with irinotecan for progressive brain metastases in small cell lung cancer, which serves as a reminder of the role of systemic chemotherapy in this setting.

  17. Vibrational resonance in adaptive small-world neuronal networks with spike-timing-dependent plasticity

    Science.gov (United States)

    Yu, Haitao; Guo, Xinmeng; Wang, Jiang; Deng, Bin; Wei, Xile

    2015-10-01

    The phenomenon of vibrational resonance is investigated in adaptive Newman-Watts small-world neuronal networks, where the strength of synaptic connections between neurons is modulated based on spike-timing-dependent plasticity. Numerical results demonstrate that there exists appropriate amplitude of high-frequency driving which is able to optimize the neural ensemble response to the weak low-frequency periodic signal. The effect of networked vibrational resonance can be significantly affected by spike-timing-dependent plasticity. It is shown that spike-timing-dependent plasticity with dominant depression can always improve the efficiency of vibrational resonance, and a small adjusting rate can promote the transmission of weak external signal in small-world neuronal networks. In addition, the network topology plays an important role in the vibrational resonance in spike-timing-dependent plasticity-induced neural systems, where the system response to the subthreshold signal is maximized by an optimal network structure. Furthermore, it is demonstrated that the introduction of inhibitory synapses can considerably weaken the phenomenon of vibrational resonance in the hybrid small-world neuronal networks with spike-timing-dependent plasticity.

  18. Surgical Treatment for Non-small Cell Lung Cancer Patients with Synchronous Solitary Brain Metastasis

    Directory of Open Access Journals (Sweden)

    Hao BAI

    2013-12-01

    Full Text Available Background and objective Brain metastases are common in non-small cell lung cancer. Usual treatments include radiotherapy and chemotherapy. However, these methods result in poor patient prognosis. The aim of this study is to assess the effectiveness of surgical resection in the multimodality management of non-small cell lung cancer patients with synchronous solitary brain metastasis. Methods The clinical data of 46 non-small cell lung cancer patients with synchronous solitary brain metastasis were retrospectively reviewed. All patients underwent surgical resection of primary lung tumor, followed by whole brain radiotherapy and chemotherapy. In addition, 13 out of the 46 patients underwent resection of brain metastasis, whereas the remaining 33 patients received stereotactic radiosurgery. Results The median survival time of the enrolled patients was 16.8 months. The 1-, 2-, and 3-year survival rates were 76.1%, 20.9%, and 4.7%, respectively. The median survival times of the patients with brain metastasis resection or stereotactic radiosurgery were 18.3 and 15.8 months, respectively (P=0.091,2. Conclusion Surgical resection of primary lung tumor and brain metastasis may improve prognosis of non-small cell lung cancer patients with synchronous solitary brain metastasis. However, the survival benefit of surgical resection over brain metastasis resection or stereotactic radiosurgery is uncertain.

  19. A Self-Organization Framework for Wireless Ad Hoc Networks as Small Worlds

    CERN Document Server

    Banerjee, Abhik; Gauthier, Vincent; Yeo, Chai Kiat; Afifi, Hossam; Lee, Bu Sung

    2012-01-01

    Motivated by the benefits of small world networks, we propose a self-organization framework for wireless ad hoc networks. We investigate the use of directional beamforming for creating long-range short cuts between nodes. Using simulation results for randomized beamforming as a guideline, we identify crucial design issues for algorithm design. Our results show that, while significant path length reduction is achievable, this is accompanied by the problem of asymmetric paths between nodes. Subsequently, we propose a distributed algorithm for small world creation that achieves path length reduction while maintaining connectivity. We define a new centrality measure that estimates the structural importance of nodes based on traffic flow in the network, which is used to identify the optimum nodes for beamforming. We show, using simulations, that this leads to significant reduction in path length while maintaining connectivity.

  20. Efficient network reconstruction from dynamical cascades identifies small-world topology of neuronal avalanches.

    Directory of Open Access Journals (Sweden)

    Sinisa Pajevic

    2009-01-01

    Full Text Available Cascading activity is commonly found in complex systems with directed interactions such as metabolic networks, neuronal networks, or disease spreading in social networks. Substantial insight into a system's organization can be obtained by reconstructing the underlying functional network architecture from the observed activity cascades. Here we focus on Bayesian approaches and reduce their computational demands by introducing the Iterative Bayesian (IB and Posterior Weighted Averaging (PWA methods. We introduce a special case of PWA, cast in nonparametric form, which we call the normalized count (NC algorithm. NC efficiently reconstructs random and small-world functional network topologies and architectures from subcritical, critical, and supercritical cascading dynamics and yields significant improvements over commonly used correlation methods. With experimental data, NC identified a functional and structural small-world topology and its corresponding traffic in cortical networks with neuronal avalanche dynamics.

  1. Synchronization transitions on small-world neuronal networks: Effects of information transmission delay and rewiring probability

    Science.gov (United States)

    Wang, Qingyun; Duan, Zhisheng; Perc, Matjaž; Chen, Guanrong

    2008-09-01

    Synchronization transitions are investigated in small-world neuronal networks that are locally modeled by the Rulkov map with additive spatiotemporal noise. In particular, we investigate the impact of different information transmission delays and rewiring probability. We show that short delays induce zigzag fronts of excitations, whereas intermediate delays can further detriment synchrony in the network due to a dynamic clustering anti-phase synchronization transition. Detailed investigations reveal, however, that for longer delay lengths the synchrony of excitations in the network can again be enhanced due to the emergence of in-phase synchronization. In addition, we show that an appropriate small-world topology can restore synchronized behavior provided information transmission delays are either short or long. On the other hand, within the intermediate delay region, which is characterized by anti-phase synchronization and clustering, differences in the network topology do not notably affect the synchrony of neuronal activity.

  2. Complete and phase synchronization in a heterogeneous small-world neuronal network

    Institute of Scientific and Technical Information of China (English)

    Han Fang; Lu Qi-Shao; Wiercigroch Marian; Ji Quan-Bao

    2009-01-01

    Synchronous firing of neurons is thought to be important for information communication in neuronal networks. This paper investigates the complete and phase synchronization in a heterogeneous small-world chaotic Hindmarsh-Rose neuronal network. The effects of various network parameters on synchronization behaviour are discussed with some biological explanations. Complete synchronization of small-world neuronal nctworks is studied theoretically by the master stability function method. It is shown that the coupling strength necessary for complete or phase synchronization decreases with the neuron number, the node degree and the connection density are increased. The cffect of heterogeneity of neuronal networks is also considered and it is found that the network heterogeneity has an advcrse effect on synchrony.

  3. Synchronization and Control of Halo-Chaos in Beam Transport Network with Small World Topology

    Institute of Scientific and Technical Information of China (English)

    LIU Qiang; FANG Jin-Qing; LI Yong

    2007-01-01

    The synchronous conditions of two kinds of the small-world (SW) network are studied.The small world topology can affect on dynamical behaviors of the beam transport network (BTN) largely,if the BTN is constructed with the SWtopology,the global linear coupling and special linear feedback can realize the synchronization control of beam halo-chaos as well as periodic state in the BTN with the SW topology,respectively.This important result can provide an effective way for the experimental study and the engineering design of the BTN in the high-current accelerator driven radioactive clean nuclear power systems,and may have potential use in prospective applications for halo-chaos secure communication.

  4. The Phase Transitions of Self-similar Small-world Networks

    Science.gov (United States)

    Brunson, Trent; Boettcher, Stefan

    2010-03-01

    A novel set of self-similar networks called Hanoi networksfootnotetextS. Boettcher, B Goncalves, Europhysics Letters 84, 30002 (2008). (HN) have been developed to study the critical phenomena of small-world networks using the renormalization group (RG). Physically, HNs contain a more desirable geometry than random small-world networks. Their structure consists of a one-dimensional backbone with a hierarchy of long-range bonds, which allows the flexibility of studying planar and non-planar networks with either a regular or exponential degree distribution. The RG and Ising model simulation results for HNs reveal unique phase transitions and non-universal behavior, which can be attributed to their hierarchical structure.footnotetextSee also http://www.physics.emory.edu/faculty/boettcher/.

  5. Renormalization and small-world model of fractal quantum repeater networks

    Science.gov (United States)

    Wei, Zong-Wen; Wang, Bing-Hong; Han, Xiao-Pu

    2013-01-01

    Quantum networks provide access to exchange of quantum information. The primary task of quantum networks is to distribute entanglement between remote nodes. Although quantum repeater protocol enables long distance entanglement distribution, it has been restricted to one-dimensional linear network. Here we develop a general framework that allows application of quantum repeater protocol to arbitrary quantum repeater networks with fractal structure. Entanglement distribution across such networks is mapped to renormalization. Furthermore, we demonstrate that logarithmical times of recursive such renormalization transformations can trigger fractal to small-world transition, where a scalable quantum small-world network is achieved. Our result provides new insight into quantum repeater theory towards realistic construction of large-scale quantum networks. PMID:23386977

  6. Renormalization and small-world model of fractal quantum repeater networks.

    Science.gov (United States)

    Wei, Zong-Wen; Wang, Bing-Hong; Han, Xiao-Pu

    2013-01-01

    Quantum networks provide access to exchange of quantum information. The primary task of quantum networks is to distribute entanglement between remote nodes. Although quantum repeater protocol enables long distance entanglement distribution, it has been restricted to one-dimensional linear network. Here we develop a general framework that allows application of quantum repeater protocol to arbitrary quantum repeater networks with fractal structure. Entanglement distribution across such networks is mapped to renormalization. Furthermore, we demonstrate that logarithmical times of recursive such renormalization transformations can trigger fractal to small-world transition, where a scalable quantum small-world network is achieved. Our result provides new insight into quantum repeater theory towards realistic construction of large-scale quantum networks.

  7. Phase Transitions of an Epidemic Spreading Model in Small-World Networks

    Institute of Scientific and Technical Information of China (English)

    HUA Da-Yin; GAO Ke

    2011-01-01

    We propose a modified susceptible-infected-refractory-susceptible (SIRS) model to investigate the global oscillations of the epidemic spreading in Watts-Strogatz (WS) small-world networks. It is found that when an individual immunity does not change or decays slowly in an immune period, the system can exhibit complex transition from an infecting stationary state to a large amplitude sustained oscillation or an absorbing state with no infection. When the immunity decays rapidly in the immune period, the transition to the global oscillation disappears and there is no oscillation. Furthermore, based on the spatio-temporal evolution patterns and the phase diagram, it is disclosed that a long immunity period takes an important role in the emergence of the global oscillation in small-world networks.

  8. Nonlinear Dynamical Behavior in Neuron Model Based on Small World Network with Attack and Repair Strategy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xue; YANG Qiu-Ying; ZHENG Tai-Yu; ZHANG Ying-Yue; ZHENG Li; ZHANG Gui-Qing; CHEN Tian-Lun

    2008-01-01

    In this paper, we investigate the effect due to the change of topology structure of network on the nonlinear dynamical behavior, by virtue of the OFC neuron evolution model with attack and repair strategy based on the small world. In particular, roles of various parameters relating to the dynamical behavior are carefully studied and analyzed. In addition, the avalanche and EEG-like wave activities with attack and repair strategy are also explored in detail in this work.

  9. Complex Behavior in an Integrate-and-Fire Neuron Model Based on Small World Networks

    Institute of Scientific and Technical Information of China (English)

    LIN Min; CHEN Tian-Lun

    2005-01-01

    Based on our previously pulse-coupled integrate-and-fire neuron model in small world networks, we investigate the complex behavior of electroencephalographic (EEG)-like activities produced by such a model. We find EEG-like activities have obvious chaotic characteristics. We also analyze the complex behaviors of EEG-like signals,such as spectral analysis, reconstruction of the phase space, the correlation dimension, and so on.

  10. Synchronization of time-delay chaotic systems on small-world networks with delayed coupling

    Institute of Scientific and Technical Information of China (English)

    Qi Wei; Wang Ying-Hai

    2009-01-01

    By using the well-known Ikeda model as the node dynamics,this paper studies synchronization of time-delay systems on small-world networks where the connections between units involve time delays.It shows that,in contrast with the undelayed case,networks with delays can actually synchronize more easily.Specifically,for randomly distributed delays,time-delayed mutual coupling suppresses the chaotic behaviour by stabilizing a fixed point that is unstable for the uncoupled dynamical system.

  11. Nonequilibrium phase transition in directed small-world-Voronoi-Delaunay random lattices

    Science.gov (United States)

    Lima, F. W. S.

    2016-01-01

    On directed small-world-Voronoi-Delaunay random lattices in two dimensions with quenched connectivity disorder we study the critical properties of the dynamics evolution of public opinion in social influence networks using a simple spin-like model. The system is treated by applying Monte Carlo simulations. We show that directed links on these random lattices may lead to phase diagram with first- and second-order social phase transitions out of equilibrium.

  12. Self-similarity, small-world, scale-free scaling, disassortativity, and robustness in hierarchical lattices

    Science.gov (United States)

    Zhang, Z.-Z.; Zhou, S.-G.; Zou, T.

    2007-04-01

    In this paper, firstly, we study analytically the topological features of a family of hierarchical lattices (HLs) from the view point of complex networks. We derive some basic properties of HLs controlled by a parameter q: scale-free degree distribution with exponent γ=2+ln 2/(ln q), null clustering coefficient, power-law behavior of grid coefficient, exponential growth of average path length (non-small-world), fractal scaling with dimension dB=ln (2q)/(ln 2), and disassortativity. Our results show that scale-free networks are not always small-world, and support the conjecture that self-similar scale-free networks are not assortative. Secondly, we define a deterministic family of graphs called small-world hierarchical lattices (SWHLs). Our construction preserves the structure of hierarchical lattices, including its degree distribution, fractal architecture, clustering coefficient, while the small-world phenomenon arises. Finally, the dynamical processes of intentional attacks and collective synchronization are studied and the comparisons between HLs and Barabási-Albert (BA) networks as well as SWHLs are shown. We find that the self-similar property of HLs and SWHLs significantly increases the robustness of such networks against targeted damage on hubs, as compared to the very vulnerable non fractal BA networks, and that HLs have poorer synchronizability than their counterparts SWHLs and BA networks. We show that degree distribution of scale-free networks does not suffice to characterize their synchronizability, and that networks with smaller average path length are not always easier to synchronize.

  13. Optimal convergence in naming game with geography-based negotiation on small-world networks

    Science.gov (United States)

    Liu, Run-Ran; Wang, Wen-Xu; Lai, Ying-Cheng; Chen, Guanrong; Wang, Bing-Hong

    2011-01-01

    We propose a negotiation strategy to address the effect of geography on the dynamics of naming games over small-world networks. Communication and negotiation frequencies between two agents are determined by their geographical distance in terms of a parameter characterizing the correlation between interaction strength and the distance. A finding is that there exists an optimal parameter value leading to fastest convergence to global consensus on naming. Numerical computations and a theoretical analysis are provided to substantiate our findings.

  14. a Small-World and Scale-Free Network Generated by Sierpinski Tetrahedron

    Science.gov (United States)

    Chen, Jin; Gao, Fei; Le, Anbo; Xi, Lifeng; Yin, Shuhua

    2016-12-01

    The Sierpinski tetrahedron is used to construct evolving networks, whose vertexes are all solid regular tetrahedra in the construction of the Sierpinski tetrahedron up to the stage t and any two vertexes are neighbors if and only if the corresponding tetrahedra are in contact with each other on boundary. We show that such networks have the small-world and scale-free effects, but are not fractal scaling.

  15. Self-Organized Criticality in Small-World Networks Based on the Social Balance Dynamics

    Institute of Scientific and Technical Information of China (English)

    MENG Qing-Kuan

    2011-01-01

    A node model is proposed to study the self-organized criticality in the small-world networks which represent the social networks. Based on the node model and the social balance dynamics, the social networks are mapped to the thermodynamic systems and the phenomena are studied with physical methods. It is found that the avalanche in the small-world networks at the critical state satisfies the power-law distribution spatially and temporally.%A node model is proposed to study the self-organized criticality in the small-world networks which represent the social networks.Based on the node model and the social balance dynamics,the social networks are mapped to the thermodynamic systems and the phenomena are studied with physical methods.It is found that the avalanche in the small-world networks at the critical state satisfies the power-law distribution spatially and temporally.The balance dynamics on social networks[1] based on the notion of social balance has been studied.[2-4]In Ref.[2],the authors studied the triad balance dynamic on a completely connected network representing a social network.At each step,they choose a triad relation from the social network and let it evolve.When the network gets dynamically balanced,they will reach the distributions of each triad relation.Moreover,other researchers subsequently carried out several studies on balance dynamics.[5,6]In this Letter,a node model is proposed to describe the triad relations,so the edge relations in Ref.[2] are changed to node relations,which may be more a universal method to study the phenomena in social networks.We will introduce the node model later.

  16. Small Worlds Week: An online celebration of planetary science using social media to reach millions

    Science.gov (United States)

    Mayo, Louis

    2015-11-01

    In celebration of the many recent discoveries from New Horizons, Dawn, Rosetta, and Cassini, NASA launched Small Worlds Week, an online, social media driven outreach program leveraging the infrastructure of Sun-Earth Days that included a robust web design, exemplary education materials, hands-on fun activities, multimedia resources, science and career highlights, and a culminating social media event. Each day from July 6-9, a new class of solar system small worlds was featured on the website: Monday-comets, Tuesday-asteroids, Wednesday-icy moons, and Thursday-dwarf planets. Then on Friday, July 10, nine scientists from Goddard Space Flight Center, Jet Propulsion Laboratory, Naval Research Laboratory, and Lunar and Planetary Institute gathered online for four hours to answer questions from the public via Facebook and Twitter. Throughout the afternoon the scientists worked closely with a social media expert and several summer interns to reply to inquirers and to archive their chats. By all accounts, Small Worlds Week was a huge success with 37 million potential views of the social media Q&A posts. The group plans to improve and replicate the program during the school year with a more classroom focus, and then to build and extend the program to be held every year. For more information, visit http:// sunearthday.nasa.gov or catch us on Twitter, #nasasww.

  17. On the agreement between small-world-like OFC model and real earthquakes

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Douglas S.R., E-mail: douglas.ferreira@ifrj.edu.br [Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro, Paracambi, RJ (Brazil); Geophysics Department, Observatório Nacional, Rio de Janeiro, RJ (Brazil); Papa, Andrés R.R., E-mail: papa@on.br [Geophysics Department, Observatório Nacional, Rio de Janeiro, RJ (Brazil); Instituto de Física, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ (Brazil); Menezes, Ronaldo, E-mail: rmenezes@cs.fit.edu [BioComplex Laboratory, Computer Sciences, Florida Institute of Technology, Melbourne (United States)

    2015-03-20

    In this article we implemented simulations of the OFC model for earthquakes for two different topologies: regular and small-world, where in the latter the links are randomly rewired with probability p. In both topologies, we have studied the distribution of time intervals between consecutive earthquakes and the border effects present in each one. In addition, we also have characterized the influence that the probability p produces in certain characteristics of the lattice and in the intensity of border effects. From the two topologies, networks of consecutive epicenters were constructed, that allowed us to analyze the distribution of connectivities of each one. In our results distributions arise belonging to a family of non-traditional distributions functions, which agrees with previous studies using data from actual earthquakes. Our results reinforce the idea that the Earth is in a critical self-organized state and furthermore point towards temporal and spatial correlations between earthquakes in different places. - Highlights: • OFC model simulations for regular and small-world topologies. • For small-world topology distributions agree remarkably well with actual earthquakes. • Reinforce the idea of a critical self-organized state for the Earth's crust. • Point towards temporal and spatial correlations between far earthquakes in far places.

  18. A small-world network derived from the deterministic uniform recursive tree by line graph operation

    Science.gov (United States)

    Hou, Pengfeng; Zhao, Haixing; Mao, Yaping; Wang, Zhao

    2016-03-01

    The deterministic uniform recursive tree ({DURT}) is one of the deterministic versions of the uniform recursive tree ({URT}). Zhang et al (2008 Eur. Phys. J. B 63 507-13) studied the properties of DURT, including its topological characteristics and spectral properties. Although DURT shows a logarithmic scaling with the size of the network, DURT is not a small-world network since its clustering coefficient is zero. Lu et al (2012 Physica A 391 87-92) proposed a deterministic small-world network by adding some edges with a simple rule in each DURT iteration. In this paper, we intoduce a method for constructing a new deterministic small-world network by the line graph operation in each DURT iteration. The line graph operation brings about cliques at each node of the previous given graph, and the resulting line graph possesses larger clustering coefficients. On the other hand, this operation can decrease the diameter at almost one, then giving the analytic solutions to several topological characteristics of the model proposed. Supported by The Ministry of Science and Technology 973 project (No. 2010C B334708); National Science Foundation of China (Nos. 61164005, 11161037, 11101232, 11461054, 11551001); The Ministry of education scholars and innovation team support plan of Yangtze River (No. IRT1068); Qinghai Province Nature Science Foundation Project (Nos. 2012-Z-943, 2014-ZJ-907).

  19. Monomer-dimer model on a scale-free small-world network

    Science.gov (United States)

    Zhang, Zhongzhi; Sheng, Yibin; Jiang, Qiang

    2012-02-01

    The explicit determination of the number of monomer-dimer arrangements on a network is a theoretical challenge, and exact solutions to monomer-dimer problem are available only for few limiting graphs with a single monomer on the boundary, e.g., rectangular lattice and quartic lattice; however, analytical research (even numerical result) for monomer-dimer problem on scale-free small-world networks is still missing despite the fact that a vast variety of real systems display simultaneously scale-free and small-world structures. In this paper, we address the monomer-dimer problem defined on a scale-free small-world network and obtain the exact formula for the number of all possible monomer-dimer arrangements on the network, based on which we also determine the asymptotic growth constant of the number of monomer-dimer arrangements in the network. We show that the obtained asymptotic growth constant is much less than its counterparts corresponding to two-dimensional lattice and Sierpinski fractal having the same average degree as the studied network, which indicates from another aspect that scale-free networks have a fundamentally distinct architecture as opposed to regular lattices and fractals without power-law behavior.

  20. Small-world network effects on innovation: evidences from nanotechnology patenting

    Science.gov (United States)

    Shi, Yuan; Guan, JianCheng

    2016-11-01

    This paper explores the effects of collaboration network on innovation in nanotechnology. We extend the idea of small-world to the heterogeneous network positions of actors by capturing the variation of how closely a given actor is connected to others in the same network and how clustered its neighbors are. We test the effects of small-world network in the context of nanotechnology patenting in China. Empirical results reveal that small-worldness, or the co-existence of high clustering and low path length in the network, displays inverse U-shape relationships with future patent output of the individual inventors and the system. Interestingly, the inflection point of the nonlinear relationship is significantly higher at the individual level. Based on these findings, we suggest that researchers of nanotechnology maintain a balance between friends in close-knit inner circles and colleagues in distant areas in their collaboration decisions and that policymakers interested in furthering the field offer collaboration opportunities for researchers in distant locations and areas.

  1. Separation Number and Generalized Clustering Coefficient in Small World Networks based on String Formalism

    CERN Document Server

    Toyota, Norihito

    2011-01-01

    We reformulated the string formalism given by Aoyama, using an adjacent matrix of a network and introduced a series of generalized clustering coefficients based on it. Furthermore we numerically evaluated Milgram condition proposed by their article in order to explore $q$-$th$ degrees of separation in scale free networks. In this article, we apply the reformulation to small world networks and numerically evaluate Milgram condition, especially the separation number of small world networks and its relation to cycle structures are discussed. Considering the number of non-zero elements of an adjacent matrix, the average path length and Milgram condition, we show that the formalism proposed by us is effective to analyze the six degrees of separation, especially effective for analyzing the relation between the separation number and cycle structures in a network. By this analysis of small world networks, it proves that a sort of power low holds between $M_n$, which is a key quantity in Milgram condition, and the gen...

  2. Dissipative stochastic sandpile model on small-world networks: Properties of nondissipative and dissipative avalanches

    Science.gov (United States)

    Bhaumik, Himangsu; Santra, S. B.

    2016-12-01

    A dissipative stochastic sandpile model is constructed and studied on small-world networks in one and two dimensions with different shortcut densities ϕ , where ϕ =0 represents regular lattice and ϕ =1 represents random network. The effect of dimension, network topology, and specific dissipation mode (bulk or boundary) on the the steady-state critical properties of nondissipative and dissipative avalanches along with all avalanches are analyzed. Though the distributions of all avalanches and nondissipative avalanches display stochastic scaling at ϕ =0 and mean-field scaling at ϕ =1 , the dissipative avalanches display nontrivial critical properties at ϕ =0 and 1 in both one and two dimensions. In the small-world regime (2-12≤ϕ ≤0.1 ) , the size distributions of different types of avalanches are found to exhibit more than one power-law scaling with different scaling exponents around a crossover toppling size sc. Stochastic scaling is found to occur for s sc . As different scaling forms are found to coexist in a single probability distribution, a coexistence scaling theory on small world network is developed and numerically verified.

  3. Genetics Home Reference: COL4A1-related brain small-vessel disease

    Science.gov (United States)

    ... hemorrhage Johns Hopkins Medicine Department of Neurology and Neurosurgery: Intracerebral Hemorrhage Johns Hopkins Medicine Department of Neurology and Neurosurgery: Stroke MalaCards: col4a1-related brain small-vessel disease ...

  4. Brain anatomical networks in world class gymnasts: a DTI tractography study.

    Science.gov (United States)

    Wang, Bin; Fan, Yuanyuan; Lu, Min; Li, Shumei; Song, Zheng; Peng, Xiaoling; Zhang, Ruibin; Lin, Qixiang; He, Yong; Wang, Jun; Huang, Ruiwang

    2013-01-15

    The excellent motor skills of world class gymnasts amaze everyone. People marvel at the way they precisely control their movements and wonder how the brain structure and function of these elite athletes differ from those of non-athletes. In this study, we acquired diffusion images from thirteen world class gymnasts and fourteen matched controls, constructed their anatomical networks, and calculated the topological properties of each network based on graph theory. From a connectivity-based analysis, we found that most of the edges with increased connection density in the champions were linked to brain regions that are located in the sensorimotor, attentional, and default-mode systems. From graph-based metrics, we detected significantly greater global and local efficiency but shorter characteristic path length in the anatomical networks of the champions compared with the controls. Moreover, in the champions we found a significantly higher nodal degree and greater regional efficiency in several brain regions that correspond to motor and attention functions. These included the left precentral gyrus, left postcentral gyrus, right anterior cingulate gyrus and temporal lobes. In addition, we revealed an increase in the mean fractional anisotropy of the corticospinal tract in the champions, possibly in response to long-term gymnastic training. Our study indicates that neuroanatomical adaptations and plastic changes occur in gymnasts' brain anatomical networks either in response to long-term intensive gymnastic training or as an innate predisposition or both. Our findings may help to explain gymnastic skills at the highest levels of performance and aid in understanding the neural mechanisms that distinguish expert gymnasts from novices.

  5. Exercise modulates redox-sensitive small GTPase activity in the brain microvasculature in a model of brain metastasis formation.

    Science.gov (United States)

    Wolff, Gretchen; Balke, Jordan E; Andras, Ibolya E; Park, Minseon; Toborek, Michal

    2014-01-01

    Tumor cell extravasation into the brain requires passage through the blood-brain barrier (BBB). There is evidence that exercise can alter the oxidation status of the brain microvasculature and protect against tumor cell invasion into the brain, although the mechanisms are not well understood. In the current study, we focused on the role of microenvironment generated by exercise and metastasizing tumor cells at the levels of brain microvessels, influencing oxidative stress-mediated responses and activation of redox-sensitive small GTPases. Mature male mice were exercised for four weeks using a running wheel with the average voluntary running distance 9.0 ± 0.3 km/day. Mice were then infused with 1.0 × 10(6) D122 (murine Lewis lung carcinoma) cells into the brain microvasculature, and euthanized either 48 hours (in short-term studies) or 2-3 weeks (in long-term studies) post tumor cell administration. A significant increase in the level of reactive oxygen species was observed following 48 hours or 3 weeks of tumor cells growth, which was accompanied by a reduction in MnSOD expression in the exercised mice. Activation of the small GTPase Rho was negatively correlated with running distance in the tumor cell infused mice. Together, these data suggest that exercise may play a significant role during aggressive metastatic invasion, especially at higher intensities in pre-trained individuals.

  6. Exercise modulates redox-sensitive small GTPase activity in the brain microvasculature in a model of brain metastasis formation.

    Directory of Open Access Journals (Sweden)

    Gretchen Wolff

    Full Text Available Tumor cell extravasation into the brain requires passage through the blood-brain barrier (BBB. There is evidence that exercise can alter the oxidation status of the brain microvasculature and protect against tumor cell invasion into the brain, although the mechanisms are not well understood. In the current study, we focused on the role of microenvironment generated by exercise and metastasizing tumor cells at the levels of brain microvessels, influencing oxidative stress-mediated responses and activation of redox-sensitive small GTPases. Mature male mice were exercised for four weeks using a running wheel with the average voluntary running distance 9.0 ± 0.3 km/day. Mice were then infused with 1.0 × 10(6 D122 (murine Lewis lung carcinoma cells into the brain microvasculature, and euthanized either 48 hours (in short-term studies or 2-3 weeks (in long-term studies post tumor cell administration. A significant increase in the level of reactive oxygen species was observed following 48 hours or 3 weeks of tumor cells growth, which was accompanied by a reduction in MnSOD expression in the exercised mice. Activation of the small GTPase Rho was negatively correlated with running distance in the tumor cell infused mice. Together, these data suggest that exercise may play a significant role during aggressive metastatic invasion, especially at higher intensities in pre-trained individuals.

  7. Targeted Therapy as an Alternative to Whole-Brain Radiotherapy in EGFR-Mutant or ALK-Positive Non-Small-Cell Lung Cancer With Brain Metastases.

    Science.gov (United States)

    Martínez, Pablo; Mak, Raymond H; Oxnard, Geoffrey R

    2017-09-01

    Is up-front whole-brain radiotherapy required to treat multiple brain metastases from non-small-cell lung cancer when highly active targeted therapies are available? Patients with EGFR-mutant or ALK-positive non-small-cell lung cancer with brain metastases now have the potential to achieve a prolonged survival. Through use of highly active targeted therapies, whole-brain radiotherapy can be safely postponed, diminishing toxic effects that could impair quality of life.

  8. EXTENDED CLUSTERING COEFFICIENTS:GENERALIZATION OF CLUSTERING COEFFICIENTS IN SMALL-WORLD NETWORKS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The clustering coefficient C of a network, which is a measure of direct connectivity between neighbors of the various nodes, ranges from 0 (for no connectivity) to 1 (for full connectivity). We define extended clustering coefficients C(h) of a small-world network based on nodes that are at distance h from a source node, thus generalizing distance-1 neighborhoods employed in computing the ordinary clustering coefficient C = C(1). Based on known results about the distance distribution Pδ(h) in a network, that is, the probability that a randomly chosen pair of vertices have distance h, we derive and experimentally validate the law Pδ(h)C(h) ≤ c log N / N, where c is a small constant that seldom exceeds 1. This result is significant because it shows that the product Pδ(h)C(h) is upper-bounded by a value that is considerably smaller than the product of maximum values for Pδ(h) and C(h). Extended clustering coefficients and laws that govern them offer new insights into the structure of small-world networks and open up avenues for further exploration of their properties.

  9. Critical behavior of the XY-rotor model on regular and small-world networks.

    Science.gov (United States)

    De Nigris, Sarah; Leoncini, Xavier

    2013-07-01

    We study the XY rotors model on small networks whose number of links scales with the system size N(links)~N(γ), where 1≤γ≤2. We first focus on regular one-dimensional rings in the microcanonical ensemble. For γ1.5, the system equilibrium properties are found to be identical to the mean field, which displays a second-order phase transition at a critical energy density ε=E/N,ε(c)=0.75. Moreover, for γ(c)~/=1.5 we find that a nontrivial state emerges, characterized by an infinite susceptibility. We then consider small-world networks, using the Watts-Strogatz mechanism on the regular networks parametrized by γ. We first analyze the topology and find that the small-world regime appears for rewiring probabilities which scale as p(SW)[proportionality]1/N(γ). Then considering the XY-rotors model on these networks, we find that a second-order phase transition occurs at a critical energy ε(c) which logarithmically depends on the topological parameters p and γ. We also define a critical probability p(MF), corresponding to the probability beyond which the mean field is quantitatively recovered, and we analyze its dependence on γ.

  10. Big ideas for small brains: what can psychiatry learn from worms, flies, bees and fish?

    Science.gov (United States)

    Burne, T; Scott, E; van Swinderen, B; Hilliard, M; Reinhard, J; Claudianos, C; Eyles, D; McGrath, J

    2011-01-01

    While the research community has accepted the value of rodent models as informative research platforms, there is less awareness of the utility of other small vertebrate and invertebrate animal models. Neuroscience is increasingly turning to smaller, non-rodent models to understand mechanisms related to neuropsychiatric disorders. Although they can never replace clinical research, there is much to be learnt from 'small brains'. In particular, these species can offer flexible genetic 'tool kits' that can be used to explore the expression and function of candidate genes in different brain regions. Very small animals also offer efficiencies with respect to high-throughput screening programs. This review provides a concise overview of the utility of models based on worm, fruit fly, honeybee and zebrafish. Although these species may have small brains, they offer the neuropsychiatric research community opportunities to explore some of the most important research questions in our field.

  11. Effects of Different Connectivity Topologies in Small World Networks on EEG-Like Activities

    Science.gov (United States)

    Lin, Min; Zhang, Gui-Qing; Chen, Tian-Lun

    2006-02-01

    Based on our previously pulse-coupled integrate-and-fire neuron model in small world networks, we investigate the effects of different connectivity topologies on complex behavior of electroencephalographic-like signals produced by this model. We show that several times series analysis methods that are often used for analyzing complex behavior of electroencephalographic-like signals, such as reconstruction of the phase space, correlation dimension, fractal dimension, and the Hurst exponent within the rescaled range analysis (R/S). We find that the different connectivity topologies lead to different dynamical behaviors in models of integrate-and-fire neurons.

  12. Effects of Different Connectivity Topologies in Small World Networks on EEG-Like Activities

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Based on our previously pulse-coupled integrate-and-fire neuron model in small world networks, we investi gate the effects of different connectivity topologies on complex behavior of electroencephalographic-like signals produced by this model. We show that several times series analysis methods that are often used for analyzing complex behavior of electroencephalographic-like signals, such as reconstruction of the phase space, correlation dimension, fractal dimension,and the Hurst exponent within the rescaled range analysis (R/S). We find that the different connectivity topologies lead to different dynamical behaviors in models of integrate-and-fire neurons.

  13. Current Redistribution in Resistor Networks: Fat-Tail Statistics in Regular and Small-World Networks

    CERN Document Server

    Lehmann, Jörg

    2016-01-01

    The redistribution of electrical currents in resistor networks after single-bond failures is analyzed in terms of current-redistribution factors that are shown to depend only on the topology of the network and on the values of the bond resistances. We investigate the properties of these current-redistribution factors for regular network topologies (e.g. $d$-dimensional hypercubic lattices) as well as for small-world networks. In particular, we find that the statistics of the current redistribution factors exhibits a fat-tail behavior, which reflects the long-range nature of the current redistribution as determined by Kirchhoff's circuit laws.

  14. Power-Aware Anycast Routing in Wireless Sensor Network Exploiting Small World Effect

    Institute of Scientific and Technical Information of China (English)

    JIANG Nan; YANG Shu-qun; LI Ling-zhi; DING Qiu-lin

    2008-01-01

    By considering energy-efficient anycast routing in wireless sensor network (WSN), and combining small world characteristics of WSN with the properties of the ant algorithm, a power-aware anycast routing algorithm (SWPAR) with multi-sink nodes is proposed and evaluated. By SWPAR, the optimal sink node is found and the problem of routing path is effectively solved. Simulation results show that compared with the sink-based anycast routing protocol (SARP) and the hierarchy-based anycast routing protocol (HARP), the proposed algorithm improves network lifetime and reduces power consumption.

  15. Chaos in complex motor networks induced byNewman-Watts small-world connections

    Institute of Scientific and Technical Information of China (English)

    WeiDu-Qu; Luo Xiao-Shu; Zhang Bo

    2011-01-01

    We investigate how dynamical behaviours of complex motor networks depend on the Newman-Watts small-world (NWSW) connections.Network elements are described by the permanent magnet synchronous motor (PMSM) with the values of parameters at which each individual PMSM is stable.It is found that with the increase of connection probability p,the motor in networks becomes periodic and falls into chaotic motion as p further increases.These phenomena imply that NWSW connections can induce and enhance chaos in motor networks.The possible mechanism behind the action of NWSW connections is addressed based on stability theory.

  16. Small World Effects in a Harmonious Unifying Hybrid Preferential Model Networks

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Small world effects in the harmonious unifying hybrid preferential model (HUHPM) networks are studied both numerically and analytically. The idea and method of the HUHPM is applied to three typical examples of unweighted BA model, weighted BBV model, and the TDE model, so-called HUHPM-BA, HUHPM-BBV and HUHPM-TDE networks. Comparing the HUHPM with current typical models above, it is found that the HUHPM networks has the smallest average path length and the biggest average clustering coefficient. The results demonstrate that the HUHPM is more suitable not only for the un-weighted models but also for the weighted models.

  17. The Peculiar Phase Transitions of the Ising Model on a Small-World Network

    Science.gov (United States)

    Brunson, Trent; Boettcher, Stefan

    2009-11-01

    To describe many collective phenomena on networks, the Ising model again plays a fundamental role. Here, we study a new network with small-world properties that can be studied exactly with the renormalization group. The network is non-planar and has a recursive design combining a one-dimensional backbone with a hierarchy of long-range bonds. Varying the relative strength between nearest-neighbor and long-range bonds, we can define a one-parameter family of models that exhibits a rich variety of critical phenomena, quite distinct from those on lattice models. Exact results and numerical simulations reveal this behavior in great detail.

  18. Current redistribution in resistor networks: Fat-tail statistics in regular and small-world networks.

    Science.gov (United States)

    Lehmann, Jörg; Bernasconi, Jakob

    2017-03-01

    The redistribution of electrical currents in resistor networks after single-bond failures is analyzed in terms of current-redistribution factors that are shown to depend only on the topology of the network and on the values of the bond resistances. We investigate the properties of these current-redistribution factors for regular network topologies (e.g., d-dimensional hypercubic lattices) as well as for small-world networks. In particular, we find that the statistics of the current redistribution factors exhibits a fat-tail behavior, which reflects the long-range nature of the current redistribution as determined by Kirchhoff's circuit laws.

  19. Synchronization of Coupled Oscillators on Newman-Watts Small-World Networks

    Institute of Scientific and Technical Information of China (English)

    GUAN Jian-Yue; XU Xin-Jian; WU Zhi-Xi; WANG Ying-Hai

    2006-01-01

    We investigate the collection behaviour of coupled phase oscillators on Newman- Watts small-world networks in one and two dimensions. Each component of the network is assumed as an oscillator and each interacts with the others following the Kuramoto model. We then study the onset of global synchronization of phases and frequencies based on dynamic simulations and finite-size scah'ng. Both the phase and frequency synchronization are observed to emerge in the presence of a tiny fraction of shortcuts and enhanced with the increases of nearest neighbours and lattice dimensions.

  20. Research on P2P Overlay Network Model with Small-world Features

    OpenAIRE

    Liu, Hao; Chen, Zhigang

    2013-01-01

    Topology structure of P2P network decides its system performance. However, the existing P2P network models don’t take clustering and symmetry of nodes into account. Based on the algebra and graph theory method of Cayley graph, this paper proposes a novel P2P overlay network model with small-world features. Its simplicity and symmetry can ensure the self-organization and scalability of P2P network. The results of analysis and experiment shows that this model provides better robustness, h...

  1. Preservation of mitochondrial functional integrity in mitochondria isolated from small cryopreserved mouse brain areas.

    Science.gov (United States)

    Valenti, Daniela; de Bari, Lidia; De Filippis, Bianca; Ricceri, Laura; Vacca, Rosa Anna

    2014-01-01

    Studies of mitochondrial bioenergetics in brain pathophysiology are often precluded by the need to isolate mitochondria immediately after tissue dissection from a large number of brain biopsies for comparative studies. Here we present a procedure of cryopreservation of small brain areas from which mitochondrial enriched fractions (crude mitochondria) with high oxidative phosphorylation efficiency can be isolated. Small mouse brain areas were frozen and stored in a solution containing glycerol as cryoprotectant. Crude mitochondria were isolated by differential centrifugation from both cryopreserved and freshly explanted brain samples and were compared with respect to their ability to generate membrane potential and produce ATP. Intactness of outer and inner mitochondrial membranes was verified by polarographic ascorbate and cytochrome c tests and spectrophotometric assay of citrate synthase activity. Preservation of structural integrity and oxidative phosphorylation efficiency was successfully obtained in crude mitochondria isolated from different areas of cryopreserved mouse brain samples. Long-term cryopreservation of small brain areas from which intact and phosphorylating mitochondria can be isolated for the study of mitochondrial bioenergetics will significantly expand the study of mitochondrial defects in neurological pathologies, allowing large comparative studies and favoring interlaboratory and interdisciplinary analyses.

  2. Isolation and functional assessment of mitochondria from small amounts of mouse brain tissue.

    Science.gov (United States)

    Chinopoulos, Christos; Zhang, Steven F; Thomas, Bobby; Ten, Vadim; Starkov, Anatoly A

    2011-01-01

    Recent discoveries have brought mitochondria functions in focus of the neuroscience research community and greatly stimulated the demand for approaches to study mitochondria dysfunction in neurodegenerative diseases. Many mouse disease models have been generated, but studying mitochondria isolated from individual mouse brain regions is a challenge because of small amount of the available brain tissue. Conventional techniques for isolation and purification of mitochondria from mouse brain subregions, such as ventral midbrain, hippocampus, or striatum, require pooling brain tissue from six to nine animals for a single mitochondrial preparation. Working with pooled tissue significantly decreases the quality of data because of the time required to dissect several brains. It also greatly increases the labor intensity and the cost of experiments as several animals are required per single data point. We describe a method for isolation of brain mitochondria from mouse striata or other 7-12 mg brain samples. The method utilizes a refrigerated table-top microtube centrifuge, and produces research grade quality mitochondria in amounts sufficient for performing multiple enzymatic and functional assays, thereby eliminating the necessity for pooling mouse brain tissue. We also include a method of measuring ADP-ATP exchange rate as a function of mitochondrial membrane potential (ΔΨm) in small amounts of isolated mitochondria, adapted to a plate reader format.

  3. Effects of Aging and Self-organized Criticality in a Pulse-Coupled Integrate-and-Fire Neuron Model Based on Small World Networks

    Institute of Scientific and Technical Information of China (English)

    ZHANG Gui-Qing; ZHANG Ying-Yue; CHEN Tian-Lun

    2007-01-01

    Effects of aging and self-organized criticality in a pulse-coupled integrate-and-fire neuron model based on small world networks have been studied. We give the degree distribution of aging network, average shortest path length,the diameter of our network, and the clustering coefficient, and find that our neuron model displays the power-law behavior, and with the number of added links increasing, the effects of aging become smaller and smaller. This shows that if the brain works at the self-organized criticality state, it can relieve some effects caused by aging.

  4. Identification and characterization of potent small molecule inhibitor of hemorrhagic fever New World arenaviruses.

    Science.gov (United States)

    Bolken, Tove C; Laquerre, Sylvie; Zhang, Yuanming; Bailey, Thomas R; Pevear, Daniel C; Kickner, Shirley S; Sperzel, Lindsey E; Jones, Kevin F; Warren, Travis K; Amanda Lund, S; Kirkwood-Watts, Dana L; King, David S; Shurtleff, Amy C; Guttieri, Mary C; Deng, Yijun; Bleam, Maureen; Hruby, Dennis E

    2006-02-01

    Category A arenaviruses as defined by the National Institute of Allergy and Infectious Diseases (NIAID) are human pathogens that could be weaponized by bioterrorists. Many of these deadly viruses require biosafety level-4 (BSL-4) containment for all laboratory work, which limits traditional laboratory high-throughput screening (HTS) for identification of small molecule inhibitors. For those reasons, a related BSL-2 New World arenavirus, Tacaribe virus, 67-78% identical to Junín virus at the amino acid level, was used in a HTS campaign where approximately 400,000 small molecule compounds were screened in a Tacaribe virus-induced cytopathic effect (CPE) assay. Compounds identified in this screen showed antiviral activity and specificity against not only Tacaribe virus, but also the Category A New World arenaviruses (Junín, Machupo, and Guanarito). Drug resistant variants were isolated, suggesting that these compounds act through inhibition of a viral protein, the viral glycoprotein (GP2), and not through cellular toxicity mechanisms. A lead compound, ST-294, has been chosen for drug development. This potent and selective compound, with good bioavailability, demonstrated protective anti-viral efficacy in a Tacaribe mouse challenge model. This series of compounds represent a new class of inhibitors that may warrant further development for potential inclusion in a strategic stockpile.

  5. Stochastic resonance enhancement of small-world neural networks by hybrid synapses and time delay

    Science.gov (United States)

    Yu, Haitao; Guo, Xinmeng; Wang, Jiang

    2017-01-01

    The synergistic effect of hybrid electrical-chemical synapses and information transmission delay on the stochastic response behavior in small-world neuronal networks is investigated. Numerical results show that, the stochastic response behavior can be regulated by moderate noise intensity to track the rhythm of subthreshold pacemaker, indicating the occurrence of stochastic resonance (SR) in the considered neural system. Inheriting the characteristics of two types of synapses-electrical and chemical ones, neural networks with hybrid electrical-chemical synapses are of great improvement in neuron communication. Particularly, chemical synapses are conducive to increase the network detectability by lowering the resonance noise intensity, while the information is better transmitted through the networks via electrical coupling. Moreover, time delay is able to enhance or destroy the periodic stochastic response behavior intermittently. In the time-delayed small-world neuronal networks, the introduction of electrical synapses can significantly improve the signal detection capability by widening the range of optimal noise intensity for the subthreshold signal, and the efficiency of SR is largely amplified in the case of pure chemical couplings. In addition, the stochastic response behavior is also profoundly influenced by the network topology. Increasing the rewiring probability in pure chemically coupled networks can always enhance the effect of SR, which is slightly influenced by information transmission delay. On the other hand, the capacity of information communication is robust to the network topology within the time-delayed neuronal systems including electrical couplings.

  6. Directed Dynamic Small-World Network Model for Worm Epidemics in Mobile ad hoc Networks

    Institute of Scientific and Technical Information of China (English)

    ZHU Chen-Ping; WANG Li; LIU Xiao-Ting; YAN Zhi-Jun

    2012-01-01

    We investigate the worm spreading process in mobile ad hoc networks with a susceptible-infected-recovered model on a two-dimensional plane.A medium access control mechanism operates within it,inhibiting transmission and relaying a message by using other nodes inside the node's transmitting circle during speaking.We measure the rewiring probability p with the transmitting range r and the average relative velocity (v) of the moving nodes,and map the problem into a directed dynamic small-world network.A new scaling relation for the recovered portion of the nodes reveals the effect caused by geometric distance,which has been ignored by previous models.%We investigate the worm spreading process in mobile ad hoc networks with a susceptible-infected-recovered model on a two-dimensional plane. A medium access control mechanism operates within it, inhibiting transmission and relaying a message by using other nodes inside the node's transmitting circle during speaking. We measure the rewiring probability p with the transmitting range r and the average relative velocity (v) of the moving nodes, and map the problem into a directed dynamic small-world network. A new scaling relation for the recovered portion of the nodes reveals the effect caused by geometric distance, which has been ignored by previous models.

  7. Smallest-Small-World Cellular Harmony Search for Optimization of Unconstrained Benchmark Problems

    Directory of Open Access Journals (Sweden)

    Sung Soo Im

    2013-01-01

    Full Text Available We presented a new hybrid method that combines cellular harmony search algorithms with the Smallest-Small-World theory. A harmony search (HS algorithm is based on musical performance processes that occur when a musician searches for a better state of harmony. Harmony search has successfully been applied to a wide variety of practical optimization problems. Most of the previous researches have sought to improve the performance of the HS algorithm by changing the pitch adjusting rate and harmony memory considering rate. However, there has been a lack of studies to improve the performance of the algorithm by the formation of population structures. Therefore, we proposed an improved HS algorithm that uses the cellular automata formation and the topological structure of Smallest-Small-World network. The improved HS algorithm has a high clustering coefficient and a short characteristic path length, having good exploration and exploitation efficiencies. Nine benchmark functions were applied to evaluate the performance of the proposed algorithm. Unlike the existing improved HS algorithm, the proposed algorithm is expected to have improved algorithmic efficiency from the formation of the population structure.

  8. Nonlinear Dynamical Behavior in BS Evolution Model Based on Small-World Network Added with Mechanism of Preferential Connection

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper, we introduce a modified small-world network added with new links with preferential connection instead of adding randomly, then we apply Bak-Sneppen (BS) evolution model on this network. Several dynamical character of the model such as the evolution graph, fo avalanche, the critical exponent D and τ, and the distribution of mutation times of all the nodes, show particular behaviors different from those of the model based on the regular network and the small-world network.

  9. Relation of cerebral small-vessel disease and brain atrophy to mild Parkinsonism in the elderly.

    Science.gov (United States)

    Reitz, Christiane; Trenkwalder, Claudia; Kretzschmar, Konrad; Roesler, Andreas; V Eckardstein, Arnold; Berger, Klaus

    2006-11-01

    The association between cerebral small-vessel disease, brain atrophy, and the risk and severity of mild parkinsonian signs (MPS) remains unclear. The objective of this study is to examine the effect of lacunar brain infarcts, cerebral white matter lesions (WMLs), and cortical atrophy on the risk and severity of MPS. This study is a cross-sectional community-based cohort study comprising 268 subjects, 65 to 83 years of age, residing in the Augsburg region of southern Germany, and without contraindications for magnetic resonance imaging (MRI) of the brain. Main outcome measures. Subcortical and periventricular WMLs, lacunar brain infarcts, and cortical atrophy determined using a standardized MRI protocol developed for the Rotterdam Scan Study and an established rating scale. MPS, assessed in a standardized neurological examination and based on the Unified Parkinson's Disease Rating Scale motor scale. Lacunar brain infarcts and large subcortical white matter lesions were associated with an elevated risk of resting tremor. More severe cortical atrophy was related to an increased risk of rigidity and bradykinesia. In a linear regression analysis relating each individual MRI measurement with the severity of MPS, the number of lacunar brain infarcts and the degree of brain atrophy were correlated with the severity of resting tremor, whereas the size of subcortical and periventricular WMLs was correlated with the severity of rigidity. A higher degree of brain atrophy was associated with increased severity of either cardinal sign. In our study, presence and volume of lacunar brain infarcts, cerebral WMLs, and cortical atrophy were associated with the risk as well as severity of MPS. Determining the presence of these brain changes using brain imaging might contribute to identify persons at risk for MPS.

  10. Adaptive Resonance Theory: how a brain learns to consciously attend, learn, and recognize a changing world.

    Science.gov (United States)

    Grossberg, Stephen

    2013-01-01

    Adaptive Resonance Theory, or ART, is a cognitive and neural theory of how the brain autonomously learns to categorize, recognize, and predict objects and events in a changing world. This article reviews classical and recent developments of ART, and provides a synthesis of concepts, principles, mechanisms, architectures, and the interdisciplinary data bases that they have helped to explain and predict. The review illustrates that ART is currently the most highly developed cognitive and neural theory available, with the broadest explanatory and predictive range. Central to ART's predictive power is its ability to carry out fast, incremental, and stable unsupervised and supervised learning in response to a changing world. ART specifies mechanistic links between processes of consciousness, learning, expectation, attention, resonance, and synchrony during both unsupervised and supervised learning. ART provides functional and mechanistic explanations of such diverse topics as laminar cortical circuitry; invariant object and scenic gist learning and recognition; prototype, surface, and boundary attention; gamma and beta oscillations; learning of entorhinal grid cells and hippocampal place cells; computation of homologous spatial and temporal mechanisms in the entorhinal-hippocampal system; vigilance breakdowns during autism and medial temporal amnesia; cognitive-emotional interactions that focus attention on valued objects in an adaptively timed way; item-order-rank working memories and learned list chunks for the planning and control of sequences of linguistic, spatial, and motor information; conscious speech percepts that are influenced by future context; auditory streaming in noise during source segregation; and speaker normalization. Brain regions that are functionally described include visual and auditory neocortex; specific and nonspecific thalamic nuclei; inferotemporal, parietal, prefrontal, entorhinal, hippocampal, parahippocampal, perirhinal, and motor cortices

  11. Prisoner's Dilemma Game with Heterogeneous Influential Effect on Regular Small-World Networks

    Institute of Scientific and Technical Information of China (English)

    WU Zhi-Xi; XU Xin-Jian; WANG Ying-Hai

    2006-01-01

    @@ The effect of heterogeneous influence of different individuals on the maintenance of co-operative behaviour is studied in an evolutionary Prisoner's Dilemma game with players located on the sites of regular small-world networks. The players interacting with their neighbours can either co-operate or defect and update their states by choosing one of the neighbours and adopting its strategy with a probability depending on the payoff difference.The selection of the neighbour obeys a preferential rule: the more influential a neighbour, the larger the probability it is picked. It is found that this simple preferential selection rule can promote continuously the co-operation of the whole population with the strengthening of the disorder of the underlying network.

  12. A Novel Memristive Multilayer Feedforward Small-World Neural Network with Its Applications in PID Control

    Directory of Open Access Journals (Sweden)

    Zhekang Dong

    2014-01-01

    Full Text Available In this paper, we present an implementation scheme of memristor-based multilayer feedforward small-world neural network (MFSNN inspirited by the lack of the hardware realization of the MFSNN on account of the need of a large number of electronic neurons and synapses. More specially, a mathematical closed-form charge-governed memristor model is presented with derivation procedures and the corresponding Simulink model is presented, which is an essential block for realizing the memristive synapse and the activation function in electronic neurons. Furthermore, we investigate a more intelligent memristive PID controller by incorporating the proposed MFSNN into intelligent PID control based on the advantages of the memristive MFSNN on computation speed and accuracy. Finally, numerical simulations have demonstrated the effectiveness of the proposed scheme.

  13. Topological Small-World Organization of the Fibroblastic Reticular Cell Network Determines Lymph Node Functionality

    Science.gov (United States)

    Abe, Jun; Bomze, David; Cremasco, Viviana; Scandella, Elke; Stein, Jens V.; Turley, Shannon J.; Ludewig, Burkhard

    2016-01-01

    Fibroblastic reticular cells (FRCs) form the cellular scaffold of lymph nodes (LNs) and establish distinct microenvironmental niches to provide key molecules that drive innate and adaptive immune responses and control immune regulatory processes. Here, we have used a graph theory-based systems biology approach to determine topological properties and robustness of the LN FRC network in mice. We found that the FRC network exhibits an imprinted small-world topology that is fully regenerated within 4 wk after complete FRC ablation. Moreover, in silico perturbation analysis and in vivo validation revealed that LNs can tolerate a loss of approximately 50% of their FRCs without substantial impairment of immune cell recruitment, intranodal T cell migration, and dendritic cell-mediated activation of antiviral CD8+ T cells. Overall, our study reveals the high topological robustness of the FRC network and the critical role of the network integrity for the activation of adaptive immune responses. PMID:27415420

  14. Small-World Connections to Induce Firing Activity and Phase Synchronization in Neural Networks

    Institute of Scientific and Technical Information of China (English)

    QIN Ying-Hua; LUO Xiao-Shu

    2009-01-01

    We investigate how the firing activity and the subsequent phase synchronization of neural networks with small-world topological connections depend on the probability p of adding-links. Network elements are described by two-dimensional map neurons (2DMNs) in a quiescent original state. Neurons burst for a given coupling strength when the topological randomness p increases, which is absent in a regular-lattice neural network. The bursting activity becomes frequent and synchronization of neurons emerges as topological randomness further increases.The maximal firing frequency and phase synchronization appear at a particular value of p. However, if the randomness p further increases, the firing frequency decreases and synchronization is apparently destroyed.

  15. Impact of mobility structure on the optimization of small-world networks of mobile agents

    CERN Document Server

    Lee, Eun

    2015-01-01

    In ad hoc wireless networking, units are connected to each other rather than to a central, fixed, infrastructure. Constructing and maintaining such networks create several trade-off problems between robustness, communication speed, power consumption, etc., that bridges engineering, computer science and the physics of complex systems. In this work, we address the role of mobility patterns of the agents on the optimal tuning of a small-world type network construction method. By this method, the network is updated periodically and held static between the updates. We investigate the optimal updating times for different scenarios of the movement of agents (modeling, for example, the fat-tailed trip distances, and periodicities, of human travel). We find that these mobility patterns affect the power consumption in non-trivial ways and discuss how these effects can best be handled.

  16. Modeling and Analysis of Epidemic Diffusion within Small-World Network

    Directory of Open Access Journals (Sweden)

    Ming Liu

    2012-01-01

    Full Text Available To depict the rule of epidemic diffusion, two different models, the Susceptible-Exposure-Infected-Recovered-Susceptible (SEIRS model and the Susceptible-Exposure-Infected-Quarantine-Recovered-Susceptible (SEIQRS model, are proposed and analyzed within small-world network in this paper. Firstly, the epidemic diffusion models are constructed with mean-filed theory, and condition for the occurrence of disease diffusion is explored. Then, the existence and global stability of the disease-free equilibrium and the endemic equilibrium for these two complex epidemic systems are proved by differential equations knowledge and Routh-Hurwiz theory. At last, a numerical example which includes key parameters analysis and critical topic discussion is presented to test how well the proposed two models may be applied in practice. These works may provide some guidelines for decision makers when coping with epidemic diffusion controlling problems.

  17. Topological Small-World Organization of the Fibroblastic Reticular Cell Network Determines Lymph Node Functionality.

    Science.gov (United States)

    Novkovic, Mario; Onder, Lucas; Cupovic, Jovana; Abe, Jun; Bomze, David; Cremasco, Viviana; Scandella, Elke; Stein, Jens V; Bocharov, Gennady; Turley, Shannon J; Ludewig, Burkhard

    2016-07-01

    Fibroblastic reticular cells (FRCs) form the cellular scaffold of lymph nodes (LNs) and establish distinct microenvironmental niches to provide key molecules that drive innate and adaptive immune responses and control immune regulatory processes. Here, we have used a graph theory-based systems biology approach to determine topological properties and robustness of the LN FRC network in mice. We found that the FRC network exhibits an imprinted small-world topology that is fully regenerated within 4 wk after complete FRC ablation. Moreover, in silico perturbation analysis and in vivo validation revealed that LNs can tolerate a loss of approximately 50% of their FRCs without substantial impairment of immune cell recruitment, intranodal T cell migration, and dendritic cell-mediated activation of antiviral CD8+ T cells. Overall, our study reveals the high topological robustness of the FRC network and the critical role of the network integrity for the activation of adaptive immune responses.

  18. Migration in a Small World: A Network Approach to Modeling Immigration Processes

    CERN Document Server

    Fotouhi, Babak

    2012-01-01

    Existing theories of migration either focus on micro- or macroscopic behavior of populations; that is, either the average behavior of entire population is modeled directly, or decisions of individuals are modeled directly. In this work, we seek to bridge these two perspectives by modeling individual agents decisions to migrate while accounting for the social network structure that binds individuals into a population. Pecuniary considerations combined with the decisions of peers are the primary elements of the model, being the main driving forces of migration. People of the home country are modeled as nodes on a small-world network. A dichotomous state is associated with each node, indicating whether it emigrates to the destination country or it stays in the home country. We characterize the emigration rate in terms of the relative welfare and population of the home and destination countries. The time evolution and the steady-state fraction of emigrants are also derived.

  19. Studies on the signal amplification in weighted and unweighted small-world networks

    Science.gov (United States)

    Gao, Yang; Wang, Jianjun; Ma, Fuqiu

    2017-02-01

    Weighted and unweighted networks composed of coupled bistable oscillators with small-world topology are investigated under the co-presence of a weak signal and multiplicative Gaussian white noise. As the noise intensity is adjusted to one or two optimal values, the temporal periodicity of the output of the system reaches the maximum, indicating the occurrence of stochastic resonance (SR) or stochastic bi-resonance (SBR). The resonance behavior is strongly-dependent on the coupling strength in both networks. At a weak coupling, SR more likely takes place; whereas at a strong coupling, SBR is prone to occur. Compared with unweighted networks, the span of coupling strength for SBR is narrower in weighted networks. In addition, the weak signal cannot be amplified so effectively in the weighted networks as in the unweighted networks, attributing to the weakening effect of the link weight on the coupling between oscillators and the heterogeneity of the whole network connectivity caused by the weight distribution.

  20. Emergence of small-world anatomical networks in self-organizing clustered neuronal cultures

    CERN Document Server

    de Santos-Sierra, Daniel; Leyva, Inmaculada; Almendral, Juan A; Anava, Sarit; Ayali, Amir; Papo, David; Boccaletti, Stefano

    2014-01-01

    In vitro primary cultures of dissociated invertebrate neurons from locust ganglia are used to experimentally investigate the morphological evolution of assemblies of living neurons, as they self-organize from collections of separated cells into elaborated, clustered, networks. At all the different stages of the culture's development, identification of neurons' and neurites' location by means of a dedicated software allows to ultimately extract an adjacency matrix from each image of the culture. In turn, a systematic statistical analysis of a group of topological observables grants us the possibility of quantifying and tracking the progression of the main network's characteristics during the self-organization process of the culture. Our results point to the existence of a particular state corresponding to a small-world network configuration, in which several relevant graph's micro- and meso-scale properties emerge. Finally, we identify the main physical processes ruling the culture's morphological transformati...

  1. SmallSat Spinning Lander with a Raman Spectrometer Payload for Future Ocean Worlds Exploration Missions

    Science.gov (United States)

    Ridenoure, R.; Angel, S. M.; Aslam, S.; Gorius, N.; Hewagama, T.; Nixon, C. A.; Sharma, S.

    2017-01-01

    We describe an Evolved Expendable Launch Vehicle Secondary Payload Adapter (ESPA)-class SmallSat spinning lander concept for the exploration of Europa or other Ocean World surfaces to ascertain the potential for life. The spinning lander will be ejected from an ESPA ring from an orbiting or flyby spacecraft and will carry on-board a standoff remote Spatial Heterodyne Raman spectrometer (SHRS) and a time resolved laser induced fluorescence spectrograph (TR-LIFS), and once landed and stationary the instruments will make surface chemical measurements. The SHRS and TR-LIFS have no moving parts have minimal mass and power requirements and will be able to characterize the surface and near-surface chemistry, including complex organic chemistry to constrain the ocean composition.

  2. Topological Small-World Organization of the Fibroblastic Reticular Cell Network Determines Lymph Node Functionality.

    Directory of Open Access Journals (Sweden)

    Mario Novkovic

    2016-07-01

    Full Text Available Fibroblastic reticular cells (FRCs form the cellular scaffold of lymph nodes (LNs and establish distinct microenvironmental niches to provide key molecules that drive innate and adaptive immune responses and control immune regulatory processes. Here, we have used a graph theory-based systems biology approach to determine topological properties and robustness of the LN FRC network in mice. We found that the FRC network exhibits an imprinted small-world topology that is fully regenerated within 4 wk after complete FRC ablation. Moreover, in silico perturbation analysis and in vivo validation revealed that LNs can tolerate a loss of approximately 50% of their FRCs without substantial impairment of immune cell recruitment, intranodal T cell migration, and dendritic cell-mediated activation of antiviral CD8+ T cells. Overall, our study reveals the high topological robustness of the FRC network and the critical role of the network integrity for the activation of adaptive immune responses.

  3. Impact of mobility structure on optimization of small-world networks of mobile agents

    Science.gov (United States)

    Lee, Eun; Holme, Petter

    2016-06-01

    In ad hoc wireless networking, units are connected to each other rather than to a central, fixed, infrastructure. Constructing and maintaining such networks create several trade-off problems between robustness, communication speed, power consumption, etc., that bridges engineering, computer science and the physics of complex systems. In this work, we address the role of mobility patterns of the agents on the optimal tuning of a small-world type network construction method. By this method, the network is updated periodically and held static between the updates. We investigate the optimal updating times for different scenarios of the movement of agents (modeling, for example, the fat-tailed trip distances, and periodicities, of human travel). We find that these mobility patterns affect the power consumption in non-trivial ways and discuss how these effects can best be handled.

  4. Dynamic range in small-world networks of Hodgkin-Huxley neurons with chemical synapses

    Science.gov (United States)

    Batista, C. A. S.; Viana, R. L.; Lopes, S. R.; Batista, A. M.

    2014-09-01

    According to Stevens' law the relationship between stimulus and response is a power-law within an interval called the dynamic range. The dynamic range of sensory organs is found to be larger than that of a single neuron, suggesting that the network structure plays a key role in the behavior of both the scaling exponent and the dynamic range of neuron assemblies. In order to verify computationally the relationships between stimulus and response for spiking neurons, we investigate small-world networks of neurons described by the Hodgkin-Huxley equations connected by chemical synapses. We found that the dynamic range increases with the network size, suggesting that the enhancement of the dynamic range observed in sensory organs, with respect to single neurons, is an emergent property of complex network dynamics.

  5. Emergence of the small-world architecture in neural networks by activity dependent growth

    Science.gov (United States)

    Gafarov, F. M.

    2016-11-01

    In this paper, we propose a model describing the growth and development of neural networks based on the latest achievements of experimental neuroscience. The model is based on two evolutionary equations. The first equation is for the evolution of the neurons state and the second is for the growth of axon tips. By using the model, we demonstrated the neuronal growth process from disconnected neurons to fully connected three-dimensional networks. For the analysis of the network's connections structure, we used the random graphs theory methods. It is shown that the growth in neural networks results in the formation of a well-known "small-world" network model. The analysis of the connectivity distribution shows the presence of a strictly non-Gaussian but no scale-free degree distribution for the in-degree node distribution. In terms of the graphs theory, this study developed a new model of dynamic graph.

  6. On the agreement between small-world-like OFC model and real earthquakes

    CERN Document Server

    Ferreira, Douglas S R; Menezes, Ronaldo

    2014-01-01

    In this article we implemented simulations of the OFC model for earthquakes for two different topologies: regular and small-world, where in the latter the links are randomly rewired with probability $p$ . In both topologies, we have studied the distribution of time intervals between consecutive earthquakes and the border effects present in each one. In addition, we also have characterized the influence that the probability $p$ produces in certain characteristics of the lattice and in the intensity of border effects. From the two topologies, networks of consecutive epicenters were constructed, that allowed us to analyze the distribution of connectivities of each one. In our results distributions arise belonging to a family of non-traditional distributions functions, which agrees with previous studies using data from actual earthquakes. Our results reinforce the idea that the Earth is in a critical self-organized state and furthermore point towards temporal and spatial correlations between earthquakes in differ...

  7. The Public Opinion Control Model Based on the Connecting Multi-Small-World-Network

    Directory of Open Access Journals (Sweden)

    Wen-Qi Zhong

    2013-09-01

    Full Text Available Based on the propagation mechanism of the rumor control, this study proposes a mode of propagation found on the information content to describe the dissemination of two opposite rumors on the same subject among crowds and sets up public opinion control model on the basis of this mode. Two opposite rumors on the same subject in our mode of propagation can respectively represent rumor and truth, so we investigate their interactions during the dissemination among crowd and simulate it in the connecting multi-small-world-network. Finally, by adjusting the factors which can affect the control effect of the model, we propose a corresponding rumor immunization strategy. Based on that, we conduct the analogy analysis of interactions of many opposite rumors on the same subject when they spread among crowds.

  8. Scale-free and small-world properties of earthquake network in Chile

    CERN Document Server

    Pasten, Denisse; Munoz, Victor; Suzuki, Norikazu

    2010-01-01

    The properties of earthquake networks have been studied so far mainly for the seismic data sets taken from California, Japan and Iran, and features common in these regions have been reported in the literature. Here, an earthquake network is constructed and analyzed for the Chilean data to examine if the scale-free and small-world properties of the earthquake networks constructed in the other geographical regions can also be found in seismicity in Chile. It is shown that the result is affirmative: in all the regions both the exponent "gamma" of the power-law connectivity distribution and the clustering coefficient C take the universal invariant values "gamma ~1" and "C~0.85", respectively, as the cell size becomes larger than a certain value, which is the scale of coarse graining needed for constructing earthquake network. An interpretation for this remarkable result is presented based on physical considerations.

  9. Research on P2P Overlay Network Model with Small-world Features

    Directory of Open Access Journals (Sweden)

    Hao LIU

    2013-09-01

    Full Text Available Topology structure of P2P network decides its system performance. However, the existing P2P network models don’t take clustering and symmetry of nodes into account. Based on the algebra and graph theory method of Cayley graph, this paper proposes a novel P2P overlay network model with small-world features. Its simplicity and symmetry can ensure the self-organization and scalability of P2P network. The results of analysis and experiment shows that this model provides better robustness, higher enquiry efficiency and better load balance than the existing P2P Overlay Network models such as Chord and CAN. Furthermore, it possesses the property of high clustering.

  10. Robustness of Diversity Induced Synchronization Transition in a Delayed Small-World Neuronal Network

    Institute of Scientific and Technical Information of China (English)

    TANG Jun; QU Li-Cheng; LUO Jin-Ming

    2011-01-01

    In a diverse and delayed small-world neuronal network, we have identified the oscillatory-like synchronization transition between anti-phase and complete synchronization [Phys. Rev. E 83(2011)046207]. Here we study the influence of the network topology and noise on the synchronization transition. The robustness of this transition is investigated. The results show that: (I) the synchronization transition is robust to the neuron number N in the network; (ii) only when the coupled neighbor number k is in the region [4,10], does the synchronization transition exist; (iii) to some extent, the synchronization is destroyed by noise and the oscillatory-like synchronization transition exists for relatively weak noise (D <0.003).%In a diverse and delayed small-world neuronal network,we have identified the oscillatory-like synchronization transition between anti-phase and complete synchronization [Phys.Rev.E 83 (2011) 046207].Here we study the influence of the network topology and noise on the synchronization transition.The robustness of this transition is investigated.The results show that:(i) the synchronization transition is robust to the neuron number N in the network;(ii) only when the coupled neighbor number k is in the region [4,10],does the synchronization transition exist;(iii) to some extent,the synchronization is destroyed by noise and the oscillatory-like synchronization transition exists for relatively weak noise (D <0.003).In the theoretical study of neuron systems,the synchronized behavior of a population of interacting neurons,namely,a neuronal network,is a hot issue due to its importance to the processing and transmission of information.[1] Many types of synchronization are identified in neuronal networks,such as complete synchronization,phase synchronization,anti-phase synchronization,phase-lock synchronization,cluster synchronization and lag synchronization.[2

  11. Gamma knife radiosurgery for multiple brain metastases from non-small cell lung cancer. Comparison with whole brain radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Serizawa, Toru; Ono, Junichi [Chiba Cardiovascular Center (Japan); Iuchi, Toshihiko; Osato, Katsunobu

    2001-04-01

    The purpose of this retrospective study is to compare the effectiveness of gamma knife radiosurgery (GKS) with that of whole-brain radiation therapy (WBRT) for multiple cerebral metastases from non-small cell lung cancer. Among 302 cases with cerebral metastases from non-small cell lung cancer treated at the Chiba Cardiovascular Center and Chiba Cancer Center between 1990 and 1999, 100 consecutive patients filling the following 4 entry criteria were analyzed in this study: Up to 10 multiple brain lesions at initial MRI study; No surgically inaccessible tumors with more than 30 mm in diameter; No carcinomatous meningitis; More than 3 months of life expectancy. The patients were divided into two groups: the GKS group (66 patients) and the WBRT group (34 patients). In the GKS group, large lesions ({>=}30mm) were removed microsurgically and all other small lesions (<30 mm) were treated by GKS. New distant lesions were treated by repeated GKS without prophylactic WBRT. In the WBRT group, the patients were treated by the traditional combined therapy of WBRT and surgery. In both groups, chemotherapy was administered according to the primary physician's protocol. The two groups did not differ in terms of age, gender, initial Karnofsky Performance Scale (KPS) score, pathology of lung caner, number, and size of brain lesion, systemic control, and chemotherapy. Overall survival (OS), neurological survival (NS) and qualitative survival (QS) of the GKS group were longer than those of the WBRT group according to Kaplan-Meier's method. In a multivariate analysis the WBRT group also had significant poor prognostic factors for OS, NS and QS. GKS without prophylactic WBRT could be a primary choice of treatment method for patients with as many as 10 cerebral metastases from non-small cell lung cancer. (author)

  12. Brain development, intelligence and cognitive outcome in children born small for gestational age.

    Science.gov (United States)

    de Bie, H M A; Oostrom, K J; Delemarre-van de Waal, H A

    2010-01-01

    Intrauterine growth restriction (IUGR) can lead to infants being born small for gestational age (SGA). SGA is associated with increased neonatal morbidity and mortality as well as short stature, cardiovascular disease, insulin resistance, diabetes mellitus type 2, dyslipidemia and end-stage renal disease in adulthood. In addition, SGA children have decreased levels of intelligence and cognition, although the effects are mostly subtle. The overall outcome of each child is the result of a complex interaction between intrauterine and extrauterine factors. Animal and human studies show structural alterations in the brains of individuals with IUGR/SGA. The presence of growth hormone (GH) receptors in the brain implies that the brain is also a target for GH. Exogenous GH theoretically has the ability to act on the brain. This is exemplified by the effects of GH on cognition in GH-deficient adults. In SGA children, data on the effect of exogenous GH on intelligence and cognition are scant and contradictory.

  13. MRI detection of brain metastases at initial staging of small-cell lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Pol, M. van de [Dept. of Neurology, Univ. Hospital, Maastricht (Netherlands); Oosterhout, A.G. van [Dept. of Neurology, Univ. Hospital, Maastricht (Netherlands); Wilmink, J.T. [Dept. of Diagnostic Radiology, Univ. Hospital, Maastricht (Netherlands); Velde, G.P.M. ten [Dept. of Pulmonology, Univ. Hospital, Maastricht (Netherlands); Twijnstra, A. [Dept. of Neurology, Univ. Hospital, Maastricht (Netherlands)

    1996-04-01

    We prospectively investigated 40 patients with small-cell carcinoma of the lung (SCLC) for signs of brain metastasis by neurological examination and MRI of the brain, to determine the significance of MRI for staging. MRI could not be completed in one patient, who was excluded from the study. The MRI studies of the remaining patients showed no abnormalities in 12, cerebral infarcts in 2 and brain metastases in 11 patients, of whom 3 no relevant symptoms. Nonenhancing white matter lesions were found in 14 patients. In 3 of the 4 patients with an abnormal neurological examination at diagnosis, nonenhancing white matter lesions later developed into contrast enhancing lesions compatible with breain metastases; in 2, this occurred during the course of the chemotherapy. MRI did not change the clinical staging in patients with asymptomatic brain metastases. (orig.)

  14. Roles for small noncoding RNAs in silencing of retrotransposons in the mammalian brain.

    Science.gov (United States)

    Nandi, Sayan; Chandramohan, Dhruva; Fioriti, Luana; Melnick, Ari M; Hébert, Jean M; Mason, Christopher E; Rajasethupathy, Priyamvada; Kandel, Eric R

    2016-10-24

    Piwi-interacting RNAs (piRNAs), long thought to be restricted to germline, have recently been discovered in neurons of Aplysia, with a role in the epigenetic regulation of gene expression underlying long-term memory. We here ask whether piwi/piRNAs are also expressed and have functional roles in the mammalian brain. Large-scale RNA sequencing and subsequent analysis of protein expression revealed the presence in brain of several piRNA biogenesis factors including a mouse piwi (Mili), as well as small RNAs, albeit at low levels, resembling conserved piRNAs in mouse testes [primarily LINE1 (long interspersed nuclear element1) retrotransposon-derived]. Despite the seeming low expression of these putative piRNAs, single-base pair CpG methylation analyses across the genome of Mili/piRNA-deficient (Mili(-/-)) mice demonstrate that brain genomic DNA is preferentially hypomethylated within intergenic areas and LINE1 promoter areas of the genome. Furthermore, Mili mutant mice exhibit behavioral deficits such as hyperactivity and reduced anxiety. These results suggest that putative piRNAs exist in mammalian brain, and similar to the role of piRNAs in testes, they may be involved in the silencing of retrotransposons, which in brain have critical roles in contributing to genomic heterogeneity underlying adaptation, stress response, and brain pathology. We also describe the presence of another class of small RNAs in the brain, with features of endogenous siRNAs, which may have taken over the role of invertebrate piRNAs in their capacity to target both transposons, as well as protein-coding genes. Thus, RNA interference through gene and retrotransposon silencing previously encountered in Aplysia may also have potential roles in the mammalian brain.

  15. Quantification of degeneracy in Hodgkin-Huxley neurons on Newman-Watts small world network.

    Science.gov (United States)

    Man, Menghua; Zhang, Ya; Ma, Guilei; Friston, Karl; Liu, Shanghe

    2016-08-07

    Degeneracy is a fundamental source of biological robustness, complexity and evolvability in many biological systems. However, degeneracy is often confused with redundancy. Furthermore, the quantification of degeneracy has not been addressed for realistic neuronal networks. The objective of this paper is to characterize degeneracy in neuronal network models via quantitative mathematic measures. Firstly, we establish Hodgkin-Huxley neuronal networks with Newman-Watts small world network architectures. Secondly, in order to calculate the degeneracy, redundancy and complexity in the ensuing networks, we use information entropy to quantify the information a neuronal response carries about the stimulus - and mutual information to measure the contribution of each subset of the neuronal network. Finally, we analyze the interdependency of degeneracy, redundancy and complexity - and how these three measures depend upon network architectures. Our results suggest that degeneracy can be applied to any neuronal network as a formal measure, and degeneracy is distinct from redundancy. Qualitatively degeneracy and complexity are more highly correlated over different network architectures, in comparison to redundancy. Quantitatively, the relationship between both degeneracy and redundancy depends on network coupling strength: both degeneracy and redundancy increase with complexity for small coupling strengths; however, as coupling strength increases, redundancy decreases with complexity (in contrast to degeneracy, which is relatively invariant). These results suggest that the degeneracy is a general topologic characteristic of neuronal networks, which could be applied quantitatively in neuroscience and connectomics.

  16. Critical properties of a dissipative sandpile model on small-world networks

    Science.gov (United States)

    Bhaumik, Himangsu; Santra, S. B.

    2013-12-01

    A dissipative sandpile model is constructed and studied on small-world networks (SWNs). SWNs are generated by adding extra links between two arbitrary sites of a two-dimensional square lattice with different shortcut densities ϕ. Three regimes are identified: regular lattice (RL) for ϕ ≲2-12, SWN for 2-12<ϕ<0.1, and random network (RN) for ϕ ≥0.1. In the RL regime, the sandpile dynamics is characterized by the usual Bak, Tang, and Weisenfeld (BTW)-type correlated scaling, whereas in the RN regime it is characterized by mean-field scaling. On SWNs, both scaling behaviors are found to coexist. Small compact avalanches below a certain characteristic size sc are found to belong to the BTW universality class, whereas large, sparse avalanches above sc are found to belong to the mean-field universality class. A scaling theory for the coexistence of two scaling forms on a SWN is developed and numerically verified. Though finite-size scaling is not valid for the dissipative sandpile model on RLs or on SWNs, it is found to be valid on RNs for the same model. Finite-size scaling on RNs appears to be an outcome of super diffusive sand transport and uncorrelated toppling waves.

  17. Effects of distance-dependent delay on small-world neuronal networks.

    Science.gov (United States)

    Zhu, Jinjie; Chen, Zhen; Liu, Xianbin

    2016-04-01

    We study firing behaviors and the transitions among them in small-world noisy neuronal networks with electrical synapses and information transmission delay. Each neuron is modeled by a two-dimensional Rulkov map neuron. The distance between neurons, which is a main source of the time delay, is taken into consideration. Through spatiotemporal patterns and interspike intervals as well as the interburst intervals, the collective behaviors are revealed. It is found that the networks switch from resting state into intermittent firing state under Gaussian noise excitation. Initially, noise-induced firing behaviors are disturbed by small time delays. Periodic firing behaviors with irregular zigzag patterns emerge with an increase of the delay and become progressively regular after a critical value is exceeded. More interestingly, in accordance with regular patterns, the spiking frequency doubles compared with the former stage for the spiking neuronal network. A growth of frequency persists for a larger delay and a transition to antiphase synchronization is observed. Furthermore, it is proved that these transitions are generic also for the bursting neuronal network and the FitzHugh-Nagumo neuronal network. We show these transitions due to the increase of time delay are robust to the noise strength, coupling strength, network size, and rewiring probability.

  18. [Targeted Therapy and Immunotherapy for Non-small Cell Lung Cancer 
with Brain Metastasis].

    Science.gov (United States)

    Song, Qi; Jiao, Shunchang; Li, Fang

    2016-08-20

    Brain metastasis, a common complication of non-small cell lung cancer (NSCLC) with an incidence rate of 30%-50%, significantly affects the patients' quality of life. The prognosis of patients of NSCLC with brain metastasis is extremely poor, the average median survival is only 1 m-2 m without treatment. The targeted therapy based on lung cancer driven gene is a new treatment. Besides, the immunotherapy which can enhance the effect of anti-cancer by simulating the immune system is a new approach. The combination of targeted therapy and immunotherapy can greatly benefit patients in clinical work.

  19. Targeted Therapy and Immunotherapy for Non-small Cell Lung Cancer 
with Brain Metastasis

    Directory of Open Access Journals (Sweden)

    Qi SONG

    2016-08-01

    Full Text Available Brain metastasis, a common complication of non-small cell lung cancer (NSCLC with an incidence rate of 30%-50%, significantly affects the patients’ quality of life. The prognosis of patients of NSCLC with brain metastasis is extremely poor, the average median survival is only 1 m-2 m without treatment. The targeted therapy based on lung cancer driven gene is a new treatment. Besides, the immunotherapy which can enhance the effect of anti-cancer by simulating the immune system is a new approach. The combination of targeted therapy and immunotherapy can greatly benefit patients in clinical work.

  20. Targeted Therapy and Immunotherapy for Non-small Cell Lung Cancer 
with Brain Metastasis

    OpenAIRE

    Song, Qi; Jiao, Shunchang; Li, Fang

    2016-01-01

    Brain metastasis, a common complication of non-small cell lung cancer (NSCLC) with an incidence rate of 30%-50%, significantly affects the patients’ quality of life. The prognosis of patients of NSCLC with brain metastasis is extremely poor, the average median survival is only 1 m-2 m without treatment. The targeted therapy based on lung cancer driven gene is a new treatment. Besides, the immunotherapy which can enhance the effect of anti-cancer by simulating the immune system is a new approa...

  1. Therapeutic potential of brain-derived neurotrophic factor (BDNF) and a small molecular mimics of BDNF for traumatic brain injury

    Science.gov (United States)

    Wurzelmann, Mary; Romeika, Jennifer; Sun, Dong

    2017-01-01

    Traumatic brain injury (TBI) is a major health problem worldwide. Following primary mechanical insults, a cascade of secondary injuries often leads to further neural tissue loss. Thus far there is no cure to rescue the damaged neural tissue. Current therapeutic strategies primarily target the secondary injuries focusing on neuroprotection and neuroregeneration. The neurotrophin brain-derived neurotrophic factor (BDNF) has significant effect in both aspects, promoting neuronal survival, synaptic plasticity and neurogenesis. Recently, the flavonoid 7,8-dihydroxyflavone (7,8-DHF), a small TrkB agonist that mimics BDNF function, has shown similar effects as BDNF in promoting neuronal survival and regeneration following TBI. Compared to BDNF, 7,8-DHF has a longer half-life and much smaller molecular size, capable of penetrating the blood-brain barrier, which makes it possible for non-invasive clinical application. In this review, we summarize functions of the BDNF/TrkB signaling pathway and studies examining the potential of BDNF and 7,8-DHF as a therapy for TBI.

  2. Therapeutic potential of brain-derived neurotrophic factor (BDNF) and a small molecular mimics of BDNF for traumatic brain injury.

    Science.gov (United States)

    Wurzelmann, Mary; Romeika, Jennifer; Sun, Dong

    2017-01-01

    Traumatic brain injury (TBI) is a major health problem worldwide. Following primary mechanical insults, a cascade of secondary injuries often leads to further neural tissue loss. Thus far there is no cure to rescue the damaged neural tissue. Current therapeutic strategies primarily target the secondary injuries focusing on neuroprotection and neuroregeneration. The neurotrophin brain-derived neurotrophic factor (BDNF) has significant effect in both aspects, promoting neuronal survival, synaptic plasticity and neurogenesis. Recently, the flavonoid 7,8-dihydroxyflavone (7,8-DHF), a small TrkB agonist that mimics BDNF function, has shown similar effects as BDNF in promoting neuronal survival and regeneration following TBI. Compared to BDNF, 7,8-DHF has a longer half-life and much smaller molecular size, capable of penetrating the blood-brain barrier, which makes it possible for non-invasive clinical application. In this review, we summarize functions of the BDNF/TrkB signaling pathway and studies examining the potential of BDNF and 7,8-DHF as a therapy for TBI.

  3. Correlations between prefrontal neurons form a small-world network that optimizes the generation of multineuron sequences of activity.

    Science.gov (United States)

    Luongo, Francisco J; Zimmerman, Chris A; Horn, Meryl E; Sohal, Vikaas S

    2016-05-01

    Sequential patterns of prefrontal activity are believed to mediate important behaviors, e.g., working memory, but it remains unclear exactly how they are generated. In accordance with previous studies of cortical circuits, we found that prefrontal microcircuits in young adult mice spontaneously generate many more stereotyped sequences of activity than expected by chance. However, the key question of whether these sequences depend on a specific functional organization within the cortical microcircuit, or emerge simply as a by-product of random interactions between neurons, remains unanswered. We observed that correlations between prefrontal neurons do follow a specific functional organization-they have a small-world topology. However, until now it has not been possible to directly link small-world topologies to specific circuit functions, e.g., sequence generation. Therefore, we developed a novel analysis to address this issue. Specifically, we constructed surrogate data sets that have identical levels of network activity at every point in time but nevertheless represent various network topologies. We call this method shuffling activity to rearrange correlations (SHARC). We found that only surrogate data sets based on the actual small-world functional organization of prefrontal microcircuits were able to reproduce the levels of sequences observed in actual data. As expected, small-world data sets contained many more sequences than surrogate data sets with randomly arranged correlations. Surprisingly, small-world data sets also outperformed data sets in which correlations were maximally clustered. Thus the small-world functional organization of cortical microcircuits, which effectively balances the random and maximally clustered regimes, is optimal for producing stereotyped sequential patterns of activity.

  4. Evidence for small scale variation in the vertebrate brain: mating strategy and sex affect brain size and structure in wild brown trout (Salmo trutta).

    Science.gov (United States)

    Kolm, N; Gonzalez-Voyer, A; Brelin, D; Winberg, S

    2009-12-01

    The basis for our knowledge of brain evolution in vertebrates rests heavily on empirical evidence from comparative studies at the species level. However, little is still known about the natural levels of variation and the evolutionary causes of differences in brain size and brain structure within-species, even though selection at this level is an important initial generator of macroevolutionary patterns across species. Here, we examine how early life-history decisions and sex are related to brain size and brain structure in wild populations using the existing natural variation in mating strategies among wild brown trout (Salmo trutta). By comparing the brains of precocious fish that remain in the river and sexually mature at a small size with those of migratory fish that migrate to the sea and sexually mature at a much larger size, we show, for the first time in any vertebrate, strong differences in relative brain size and brain structure across mating strategies. Precocious fish have larger brain size (when controlling for body size) but migratory fish have a larger cerebellum, the structure in charge of motor coordination. Moreover, we demonstrate sex-specific differences in brain structure as female precocious fish have a larger brain than male precocious fish while males of both strategies have a larger telencephalon, the cognitive control centre, than females. The differences in brain size and structure across mating strategies and sexes thus suggest the possibility for fine scale adaptive evolution of the vertebrate brain in relation to different life histories.

  5. Three-state Potts model on non-local directed small-world lattices

    Science.gov (United States)

    Ferraz, Carlos Handrey Araujo; Lima, José Luiz Sousa

    2017-10-01

    In this paper, we study the non-local directed Small-World (NLDSW) disorder effects in the three-state Potts model as a form to capture the essential features shared by real complex systems where non-locality effects play a important role in the behavior of these systems. Using Monte Carlo techniques and finite-size scaling analysis, we estimate the infinite lattice critical temperatures and the leading critical exponents in this model. In particular, we investigate the first- to second-order phase transition crossover when NLDSW links are inserted. A cluster-flip algorithm was used to reduce the critical slowing down effect in our simulations. We find that for a NLDSW disorder densities p

  6. Geographical threshold graphs with small-world and scale-free properties

    Science.gov (United States)

    Masuda, Naoki; Miwa, Hiroyoshi; Konno, Norio

    2005-03-01

    Many real networks are equipped with short diameters, high clustering, and power-law degree distributions. With preferential attachment and network growth, the model by Barabási and Albert simultaneously reproduces these properties, and geographical versions of growing networks have also been analyzed. However, nongrowing networks with intrinsic vertex weights often explain these features more plausibly, since not all networks are really growing. We propose a geographical nongrowing network model with vertex weights. Edges are assumed to form when a pair of vertices are spatially close and/or have large summed weights. Our model generalizes a variety of models as well as the original nongeographical counterpart, such as the unit disk graph, the Boolean model, and the gravity model, which appear in the contexts of percolation, wire communication, mechanical and solid physics, sociology, economy, and marketing. In appropriate configurations, our model produces small-world networks with power-law degree distributions. We also discuss the relation between geography, power laws in networks, and power laws in general quantities serving as vertex weights.

  7. IMDB network revisited: unveiling fractal and modular properties from a typical small-world network.

    Directory of Open Access Journals (Sweden)

    Lazaros K Gallos

    Full Text Available We study a subset of the movie collaboration network, http://www.imdb.com, where only adult movies are included. We show that there are many benefits in using such a network, which can serve as a prototype for studying social interactions. We find that the strength of links, i.e., how many times two actors have collaborated with each other, is an important factor that can significantly influence the network topology. We see that when we link all actors in the same movie with each other, the network becomes small-world, lacking a proper modular structure. On the other hand, by imposing a threshold on the minimum number of links two actors should have to be in our studied subset, the network topology becomes naturally fractal. This occurs due to a large number of meaningless links, namely, links connecting actors that did not actually interact. We focus our analysis on the fractal and modular properties of this resulting network, and show that the renormalization group analysis can characterize the self-similar structure of these networks.

  8. Continuous Forest Fire Propagation in a Local Small World Network Model

    CERN Document Server

    Aguayo, F; Clerc, J -P; Porterie, B

    2013-01-01

    This paper presents the development of a new continuous forest fire model implemented as a weighted local small-world network approach. This new approach was designed to simulate fire patterns in real, heterogeneous landscapes. The wildland fire spread is simulated on a square lattice in which each cell represents an area of the land's surface. The interaction between burning and non-burning cells, in the present work induced by flame radiation, may be extended well beyond nearest neighbors. It depends on local conditions of topography and vegetation types. An approach based on a solid flame model is used to predict the radiative heat flux from the flame generated by the burning of each site towards its neighbors. The weighting procedure takes into account the self-degradation of the tree and the ignition processes of a combustible cell through time. The model is tested on a field presenting a range of slopes and with data collected from a real wildfire scenario. The critical behavior of the spreading process...

  9. Laplacian spectra of recursive treelike small-world polymer networks: analytical solutions and applications.

    Science.gov (United States)

    Liu, Hongxiao; Zhang, Zhongzhi

    2013-03-21

    A central issue in the study of polymer physics is to understand the relation between the geometrical properties of macromolecules and various dynamics, most of which are encoded in the Laplacian spectra of a related graph describing the macrostructural structure. In this paper, we introduce a family of treelike polymer networks with a parameter, which has the same size as the Vicsek fractals modeling regular hyperbranched polymers. We study some relevant properties of the networks and show that they have an exponentially decaying degree distribution and exhibit the small-world behavior. We then study the Laplacian eigenvalues and their corresponding eigenvectors of the networks under consideration, with both quantities being determined through the recursive relations deduced from the network structure. Using the obtained recursive relations we can find all the eigenvalues and eigenvectors for the networks with any size. Finally, as some applications, we use the eigenvalues to study analytically or semi-analytically three dynamical processes occurring in the networks, including random walks, relaxation dynamics in the framework of generalized Gaussian structure, as well as the fluorescence depolarization under quasiresonant energy transfer. Moreover, we compare the results with those corresponding to Vicsek fractals, and show that the dynamics differ greatly for the two network families, which thus enables us to distinguish between them.

  10. The dynamic consequences of cooperation and competition in small-world networks.

    Science.gov (United States)

    Fernández-Rosales, Iván Y; Liebovitch, Larry S; Guzmán-Vargas, Lev

    2015-01-01

    We present a study of the social dynamics among cooperative and competitive actors interacting on a complex network that has a small-world topology. In this model, the state of each actor depends on its previous state in time, its inertia to change, and the influence of its neighboring actors. Using numerical simulations, we determine how the distribution of final states of the actors and measures of the distances between the values of the actors at local and global levels, depend on the number of cooperative to competitive actors and the connectivity of the actors in the network. We find that similar numbers of cooperative and competitive actors yield the lowest values for the local and global measures of the distances between the values of the actors. On the other hand, when the number of either cooperative or competitive actors dominate the system, then the divergence is largest between the values of the actors. Our findings make new testable predictions on how the dynamics of a conflict depends on the strategies chosen by groups of actors and also have implications for the evolution of behaviors.

  11. Hybrid Control of Delay Induced Hopf Bifurcation of Dynamical Small-World Network

    Institute of Scientific and Technical Information of China (English)

    DING Dawei; ZHANG Xiaoyun; WANG Nian; LIANG Dong

    2017-01-01

    In this paper,we focus on the Hopf bifurcation control of a small-world network model with time-delay.With emphasis on the relationship between the Hopf bifurcation and the time-delay,we investigate the effect of time-delay by choosing it as the bifurcation parameter.By using tools from control and bifurcation theory,it is proved that there exists a critical value of time-delay for the stability of the model.When the time-delay passes through the critical value,the model loses its stability and a Hopf bifurcation occurs.To enhance the stability of the model,we propose an improved hybrid control strategy in which state feedback and parameter perturbation are used.Through linear stability analysis,we show that by adjusting the control parameter properly,the onset of Hopf bifurcation of the controlled model can be delayed or eliminated without changing the equilibrium point of the model.Finally,numerical simulations are given to verify the theoretical analysis.

  12. Emergence of small-world anatomical networks in self-organizing clustered neuronal cultures.

    Directory of Open Access Journals (Sweden)

    Daniel de Santos-Sierra

    Full Text Available In vitro primary cultures of dissociated invertebrate neurons from locust ganglia are used to experimentally investigate the morphological evolution of assemblies of living neurons, as they self-organize from collections of separated cells into elaborated, clustered, networks. At all the different stages of the culture's development, identification of neurons' and neurites' location by means of a dedicated software allows to ultimately extract an adjacency matrix from each image of the culture. In turn, a systematic statistical analysis of a group of topological observables grants us the possibility of quantifying and tracking the progression of the main network's characteristics during the self-organization process of the culture. Our results point to the existence of a particular state corresponding to a small-world network configuration, in which several relevant graph's micro- and meso-scale properties emerge. Finally, we identify the main physical processes ruling the culture's morphological transformations, and embed them into a simplified growth model qualitatively reproducing the overall set of experimental observations.

  13. A Space-Filling Visualization Technique for Multivariate Small World Graphs

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Pak C.; Foote, Harlan P.; Mackey, Patrick S.; Chin, George; Huang, Zhenyu; Thomas, James J.

    2012-03-15

    We introduce an information visualization technique, known as GreenCurve, for large sparse graphs that exhibit small world properties. Our fractal-based design approach uses spatial cues to approximate the node connections and thus eliminates the links between the nodes in the visualization. The paper describes a sophisticated algorithm to order the neighboring nodes of a large sparse graph by solving the Fiedler vector of its graph Laplacian, and then fold the graph nodes into a space-filling fractal curve based on the Fiedler vector. The result is a highly compact visualization that gives a succinct overview of the graph with guaranteed visibility of every graph node. We show in the paper that the GreenCurve technology is (1) theoretically sustainable by introducing an error estimation metric to measure the fidelity of the new graph representation, (2) empirically rigorous by conducting a usability study to investigate its strengths and weaknesses against the traditional graph layout, and (3) pragmatically feasible by applying it to analyze stressed conditions of the large scale electric power grid on the west coast.

  14. Navigation on Power-Law Small World Network with Incomplete Information

    Institute of Scientific and Technical Information of China (English)

    CHEN Jian-Zhen; ZHU Jian-Yang

    2007-01-01

    We investigate the navigation process on a variant of the Watts-Strogatz small-world network model with local information. In the network construction, each vertex of an N × N square lattice sends out a long-range link with probability p. The other end of the link falls on a randomly chosen vertex with probability proportional to r-α, where r is the lattice distance between the two vertices, and α ≥ 0. The average actual path length,i.e. the expected number of steps for passing messages between randomly chosen vertex pairs, is found to scale as a power-law function of the network size Nβ, except when α is close to a specific value αmin, which gives the highest efficiency of message navigation. For a finite network, the exponent β depends on both α and p, and αmin drops to zero at a critical value of p which depends on N. When the network size goes to infinity,β depends only on α, and αmin is equal to the network dimensionality.

  15. The dynamic consequences of cooperation and competition in small-world networks.

    Directory of Open Access Journals (Sweden)

    Iván Y Fernández-Rosales

    Full Text Available We present a study of the social dynamics among cooperative and competitive actors interacting on a complex network that has a small-world topology. In this model, the state of each actor depends on its previous state in time, its inertia to change, and the influence of its neighboring actors. Using numerical simulations, we determine how the distribution of final states of the actors and measures of the distances between the values of the actors at local and global levels, depend on the number of cooperative to competitive actors and the connectivity of the actors in the network. We find that similar numbers of cooperative and competitive actors yield the lowest values for the local and global measures of the distances between the values of the actors. On the other hand, when the number of either cooperative or competitive actors dominate the system, then the divergence is largest between the values of the actors. Our findings make new testable predictions on how the dynamics of a conflict depends on the strategies chosen by groups of actors and also have implications for the evolution of behaviors.

  16. Small-world network model of propagation of the AIDS epidemic

    Science.gov (United States)

    Shi, Pengliang; Small, Michael

    2004-03-01

    Sexual contact and intravenus drug-use are the most common modes of transmission of HIV-AIDS. In this paper, homogenerous and heterogeneous models are proposed to model the dynamics in a system contains Small-World clusters. Four high risk groups: intravenus drug-users (D); homosexuals (H); individuals with multiple-sexual partners (M) and prostitutes (P), are classified using two models. Both networks are embedded among a background (low-risk) population using rich-get-richer preferential attachment. When a network is established, an epidemic is simulated in it by seeding randomly. We compare the two epidemic networks in detail and consider the effect of different levels of control policies in both. This study highlights two main conclusions: (i) set high protection coefficient for a massive-linkage-vertex (i.e. protect the highly connected individuals); and, (ii) a quick removal for the infected massive-linkage-veterx from the network is essential (rapidly quarantine infected individuals). While these conclusions may be intuitive, they indicate a necessary change of public policy toward prostitution in some developing countries such as China and India. An active effort to prevent possible infection from super-spreader is recommended.

  17. Effects of time delay and random rewiring on the stochastic resonance in excitable small-world neuronal networks.

    Science.gov (United States)

    Yu, Haitao; Wang, Jiang; Du, Jiwei; Deng, Bin; Wei, Xile; Liu, Chen

    2013-05-01

    The effects of time delay and rewiring probability on stochastic resonance and spatiotemporal order in small-world neuronal networks are studied in this paper. Numerical results show that, irrespective of the pacemaker introduced to one single neuron or all neurons of the network, the phenomenon of stochastic resonance occurs. The time delay in the coupling process can either enhance or destroy stochastic resonance on small-world neuronal networks. In particular, appropriately tuned delays can induce multiple stochastic resonances, which appear intermittently at integer multiples of the oscillation period of the pacemaker. More importantly, it is found that the small-world topology can significantly affect the stochastic resonance on excitable neuronal networks. For small time delays, increasing the rewiring probability can largely enhance the efficiency of pacemaker-driven stochastic resonance. We argue that the time delay and the rewiring probability both play a key role in determining the ability of the small-world neuronal network to improve the noise-induced outreach of the localized subthreshold pacemaker.

  18. The future of the brain essays by the world's leading neuroscientists

    CERN Document Server

    Freeman, Jeremy

    2015-01-01

    An unprecedented look at the quest to unravel the mysteries of the human brain, The Future of the Brain takes readers to the absolute frontiers of science. Original essays by leading researchers such as Christof Koch, George Church, Olaf Sporns, and May-Britt and Edvard Moser describe the spectacular technological advances that will enable us to map the more than eighty-five billion neurons in the brain, as well as the challenges that lie ahead in understanding the anticipated deluge of data and the prospects for building working simulations of the human brain. A must-read for anyone trying to understand ambitious new research programs such as the Obama administration's BRAIN Initiative and the European Union’s Human Brain Project, The Future of the Brain sheds light on the breathtaking implications of brain science for medicine, psychiatry, and even human consciousness itself.

  19. Gamma Knife irradiation method based on dosimetric controls to target small areas in rat brains

    Energy Technology Data Exchange (ETDEWEB)

    Constanzo, Julie; Paquette, Benoit; Charest, Gabriel [Center for Radiotherapy Research, Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, 3001 12th Avenue Nord, Sherbrooke, Québec J1H 5N4 (Canada); Masson-Côté, Laurence; Guillot, Mathieu, E-mail: mathieu.guillot@usherbrooke.ca [Department of Radiation Oncology, Centre Hospitalier Universitaire de Sherbrooke, 3001 12th Avenue Nord, Sherbrooke, Québec J1H 5N4, Canada and Center for Radiotherapy Research, Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, 3001 12th Avenue Nord, Sherbrooke, Québec J1H 5N4 (Canada)

    2015-05-15

    Purpose: Targeted and whole-brain irradiation in humans can result in significant side effects causing decreased patient quality of life. To adequately investigate structural and functional alterations after stereotactic radiosurgery, preclinical studies are needed. The purpose of this work is to establish a robust standardized method of targeted irradiation on small regions of the rat brain. Methods: Euthanized male Fischer rats were imaged in a stereotactic bed, by computed tomography (CT), to estimate positioning variations relative to the bregma skull reference point. Using a rat brain atlas and the stereotactic bregma coordinates obtained from CT images, different regions of the brain were delimited and a treatment plan was generated. A single isocenter treatment plan delivering ≥100 Gy in 100% of the target volume was produced by Leksell GammaPlan using the 4 mm diameter collimator of sectors 4, 5, 7, and 8 of the Gamma Knife unit. Impact of positioning deviations of the rat brain on dose deposition was simulated by GammaPlan and validated with dosimetric measurements. Results: The authors’ results showed that 90% of the target volume received 100 ± 8 Gy and the maximum of deposited dose was 125 ± 0.7 Gy, which corresponds to an excellent relative standard deviation of 0.6%. This dose deposition calculated with GammaPlan was validated with dosimetric films resulting in a dose-profile agreement within 5%, both in X- and Z-axes. Conclusions: The authors’ results demonstrate the feasibility of standardizing the irradiation procedure of a small volume in the rat brain using a Gamma Knife.

  20. Whole Brain Irradiation and Hypo-fractionation Radiotherapy for the Metastases in Non-small Cell Lung Cancer

    Directory of Open Access Journals (Sweden)

    Xingting GU

    2016-04-01

    Full Text Available Up to 40% non-small cell lung cancer patients developed brain metastasis during progression. Multiple brain metastases are common in non-small cell lung cancer. The prognosis of brain metastasis is poor with median survival of less than 1 year. Radio therapy for brain metastases has gradually developed from whole brain radiotherapy (WBRT to various radiation strategies. WBRT, surgery+WBRT, stereotactic radiotherapy+WBRT or WBRT with simultaneous integrated boost (SIB, etc. have better overall survival than those untreated patients. The damage of the cognitive function from WBRT has been realized recently, however, options of radiation strategies for long expected survival patients remain controversial. This paper will discuss different WBRT strategies and treatment side effects of non-small cell lung cancer with brain metastases.

  1. Advances in Treatment of Brain Metastases 
from Primary Non-small Cell Lung Cancer

    Directory of Open Access Journals (Sweden)

    Gen LIN

    2014-12-01

    Full Text Available Metastatic tumors involving the brain are an important complication in the overall management of non-small cell lung cancers. Surgery and radiation remain the cornerstones of the therapy, however, the burgeoning knowledge of tumor biology has facilitated the entry of systemically administered therapies into the clinic. This review mainly summarizes the current applications of these data to surgery, radiation therapy, chemotherapy and targeted therapy.

  2. Prognosis of non-small cell lung cancer with brain metastases and the clinical role of cranial irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Tsuyoshi; Katakami, Nobuyuki; Tomioka, Hiromi; Okazaki, Miki; Sakamoto, Hiroko; Ishihara, Kyosuke; Iwasaki, Hironobu; Umeda, Fumikazu; Nakai, Hitoshi (Kobe City General Hospital, Hyogo (Japan))

    1990-10-01

    Prognosis of 95 consecutive patients with non-small cell lung cancer with brain metastases were evaluated. Three factors, therapy for brain metastases, general performance status (PS) and distant metastases to other organs had significant impact on survival. Among these 3 factors, PS was independent from the other 2 factors. Significant correlation was present, however, between therapy and other organ metastases, and few patients with brain and other distant metastases received aggressive treatment for brain metastases. Cranial irradiation had significant impact on survival even in those patients with brain and other distant metastases. Cranial irradiation also reduced death from brain metastases in responders. Our results indicate that there are several subgroups with different prognosis in patients with non-small cell lung cancer with brain metastases, therefore the most beneficial treatment modality should be selected for each group of patients. (author).

  3. Impact of small vessel disease in the brain on gait and balance

    Science.gov (United States)

    Pinter, Daniela; Ritchie, Stuart J.; Doubal, Fergus; Gattringer, Thomas; Morris, Zoe; Bastin, Mark E.; del C. Valdés Hernández, Maria; Royle, Natalie A.; Corley, Janie; Muñoz Maniega, Susana; Pattie, Alison; Dickie, David A.; Staals, Julie; Gow, Alan J.; Starr, John M.; Deary, Ian J.; Enzinger, Christian; Fazekas, Franz; Wardlaw, Joanna

    2017-01-01

    Gait and balance impairment is highly prevalent in older people. We aimed to assess whether and how single markers of small vessel disease (SVD) or a combination thereof explain gait and balance function in the elderly. We analysed 678 community-dwelling healthy subjects from the Lothian Birth Cohort 1936 at the age of 71–74 years who had undergone comprehensive risk factor assessment, gait and balance assessment as well as brain MRI. We investigated the impact of individual SVD markers (white matter hyperintensity – WMH, microbleeds, lacunes, enlarged perivascular spaces, brain atrophy) as seen on structural brain MRI and of a global SVD score on the patients’ performance. A regression model revealed that age, sex, and hypertension significantly explained gait speed. Among SVD markers white matter hyperintensity (WMH) score or volume were additional significant and independent predictors of gait speed in the regression model. A similar association was seen with the global SVD score. Our study confirms a negative impact of SVD-related morphologic brain changes on gait speed in addition to age, sex and hypertension independent from brain atrophy. The presence of WMH seems to be the major driving force for SVD on gait impairment in healthy elderly subjects. PMID:28134332

  4. Impact of small vessel disease in the brain on gait and balance.

    Science.gov (United States)

    Pinter, Daniela; Ritchie, Stuart J; Doubal, Fergus; Gattringer, Thomas; Morris, Zoe; Bastin, Mark E; Del C Valdés Hernández, Maria; Royle, Natalie A; Corley, Janie; Muñoz Maniega, Susana; Pattie, Alison; Dickie, David A; Staals, Julie; Gow, Alan J; Starr, John M; Deary, Ian J; Enzinger, Christian; Fazekas, Franz; Wardlaw, Joanna

    2017-01-30

    Gait and balance impairment is highly prevalent in older people. We aimed to assess whether and how single markers of small vessel disease (SVD) or a combination thereof explain gait and balance function in the elderly. We analysed 678 community-dwelling healthy subjects from the Lothian Birth Cohort 1936 at the age of 71-74 years who had undergone comprehensive risk factor assessment, gait and balance assessment as well as brain MRI. We investigated the impact of individual SVD markers (white matter hyperintensity - WMH, microbleeds, lacunes, enlarged perivascular spaces, brain atrophy) as seen on structural brain MRI and of a global SVD score on the patients' performance. A regression model revealed that age, sex, and hypertension significantly explained gait speed. Among SVD markers white matter hyperintensity (WMH) score or volume were additional significant and independent predictors of gait speed in the regression model. A similar association was seen with the global SVD score. Our study confirms a negative impact of SVD-related morphologic brain changes on gait speed in addition to age, sex and hypertension independent from brain atrophy. The presence of WMH seems to be the major driving force for SVD on gait impairment in healthy elderly subjects.

  5. The Analysis of Erlotinib on Brain Metastases in Patients with Non-small-cell Lung Cancer

    Directory of Open Access Journals (Sweden)

    Baohui HAN

    2009-12-01

    Full Text Available Background and objective Brain metastases are common in non-small-cell lung cancer (NSCLC and the prognosis is poor. Erlotinib is a specific inhibitor of the epidermal growth factor receptor-associated tyrosine kinase (EGFRTKI, which has been gradually used in the treatment for advanced NSCLC. The aim of this study is to evaluate the antitumor efficacy and its relevant factors of erlotinib in NSCLC patients with brain metastases. Methods The clinical data of 30 NSCLC patients with brain metastases were reviewed retrospectively. All of them were treated with erlotinib, given orally 150mg daily. These patients discontinued administration of erlotinib until disease progression, death or intolerable side effects. Results In terms of intracranial lesions, partial response (PR was observed in 2 patients (6.7%, with stable disease (SD in 17 patients (56.7%, for overall disease control rate (DCR of 63.4%. As for systemic disease, PR was observed in 2 patients (6.7%, with SD in 5 patients (16.7%, for overall DCR of 23.4%. There was no statistical difference in DCR among different subtypes of age, gender, smoking history, histology, PS score, the number of brain metastases, the onset of brain metastases, chemotherapy, brain radiotherapy and side effects. The median time to disease progression (MTTP and median survival time (MST was 2.4 months and 7.7 months respectively. The 1 and 2 year survival rate was 38.4% and 15.2%. The univariate analysis showed that the survival time was related to the patients’ PS score, smoking history, brain radiotherapy and chemotherapy. The multivariate analysis indicated that brain radiotherapy was the independent prognostic factor and the relationship between the survival time and smoking history was near to statistical significance. Conclusion The patients receiving brain radiotherapy may have better survival benefit. Non-smokers have a trend to survive longer than smokers. Erlotinib may be effective on brain metastases

  6. Autaptic pacemaker mediated propagation of weak rhythmic activity across small-world neuronal networks

    Science.gov (United States)

    Yilmaz, Ergin; Baysal, Veli; Ozer, Mahmut; Perc, Matjaž

    2016-02-01

    We study the effects of an autapse, which is mathematically described as a self-feedback loop, on the propagation of weak, localized pacemaker activity across a Newman-Watts small-world network consisting of stochastic Hodgkin-Huxley neurons. We consider that only the pacemaker neuron, which is stimulated by a subthreshold periodic signal, has an electrical autapse that is characterized by a coupling strength and a delay time. We focus on the impact of the coupling strength, the network structure, the properties of the weak periodic stimulus, and the properties of the autapse on the transmission of localized pacemaker activity. Obtained results indicate the existence of optimal channel noise intensity for the propagation of the localized rhythm. Under optimal conditions, the autapse can significantly improve the propagation of pacemaker activity, but only for a specific range of the autaptic coupling strength. Moreover, the autaptic delay time has to be equal to the intrinsic oscillation period of the Hodgkin-Huxley neuron or its integer multiples. We analyze the inter-spike interval histogram and show that the autapse enhances or suppresses the propagation of the localized rhythm by increasing or decreasing the phase locking between the spiking of the pacemaker neuron and the weak periodic signal. In particular, when the autaptic delay time is equal to the intrinsic period of oscillations an optimal phase locking takes place, resulting in a dominant time scale of the spiking activity. We also investigate the effects of the network structure and the coupling strength on the propagation of pacemaker activity. We find that there exist an optimal coupling strength and an optimal network structure that together warrant an optimal propagation of the localized rhythm.

  7. The Tutte polynomial of an infinite family of outerplanar, small-world and self-similar graphs

    Science.gov (United States)

    Liao, Yunhua; Fang, Aixiang; Hou, Yaoping

    2013-10-01

    In this paper we recursively describe the Tutte polynomial of an infinite family of outerplanar, small-world and self-similar graphs. In particular, we study the Abelian Sandpile Model on these graphs and obtain the generating function of the recurrent configurations. Further, we give some exact analytical expression for the Tutte polynomial at several special points

  8. Longitudinal patterns of leukoaraiosis and brain atrophy in symptomatic small vessel disease.

    Science.gov (United States)

    Lambert, Christian; Benjamin, Philip; Zeestraten, Eva; Lawrence, Andrew J; Barrick, Thomas R; Markus, Hugh S

    2016-04-01

    Cerebral small vessel disease is a common condition associated with lacunar stroke, cognitive impairment and significant functional morbidity. White matter hyperintensities and brain atrophy, seen on magnetic resonance imaging, are correlated with increasing disease severity. However, how the two are related remains an open question. To better define the relationship between white matter hyperintensity growth and brain atrophy, we applied a semi-automated magnetic resonance imaging segmentation analysis pipeline to a 3-year longitudinal cohort of 99 subjects with symptomatic small vessel disease, who were followed-up for ≥1 years. Using a novel two-stage warping pipeline with tissue repair step, voxel-by-voxel rate of change maps were calculated for each tissue class (grey matter, white matter, white matter hyperintensities and lacunes) for each individual. These maps capture both the distribution of disease and spatial information showing local rates of growth and atrophy. These were analysed to answer three primary questions: first, is there a relationship between whole brain atrophy and magnetic resonance imaging markers of small vessel disease (white matter hyperintensities or lacune volume)? Second, is there regional variation within the cerebral white matter in the rate of white matter hyperintensity progression? Finally, are there regionally specific relationships between the rates of white matter hyperintensity progression and cortical grey matter atrophy? We demonstrate that the rates of white matter hyperintensity expansion and grey matter atrophy are strongly correlated (Pearson's R = -0.69, P atrophy occurs annually (P atrophy rates, in the medial-frontal, orbito-frontal, parietal and occipital regions. Conversely, increased rates of global grey matter atrophy are significantly associated with faster white matter hyperintensity growth in the frontal and parietal regions. Together, these results link the progression of white matter hyperintensities

  9. Clinical Features of Brain Metastases in Small Cell Lung Cancer: an Implication for Hippocampal Sparing Whole Brain Radiation Therapy

    Directory of Open Access Journals (Sweden)

    Wen-Long Guo

    2017-02-01

    Full Text Available PURPOSE: To assess the clinical features and distribution of brain metastases (BMs of small cell lung cancer (SCLC in the hippocampal and perihippocampal region, with the purpose of exploring the viability of hippocampal-sparing whole-brain radiation therapy (HS-WBRT on reducing neurocognitive deficits. METHODS: This was a retrospective analysis of the clinical characteristics and patterns of BMs in patients with SCLC. Associations between the clinical characteristics and hippocampal metastases (HMs/perihippocampal metastases (PHMs were evaluated in univariate and multivariate regression analyses. RESULTS: A total of 1594 brain metastatic lesions were identified in 180 patients. Thirty-two (17.8% patients were diagnosed with BMs at the time of primary SCLC diagnosis. The median interval between diagnosis of primary SCLC and BMs was 9.3 months. There were 9 (5.0% and 22 (12.2% patients with HMs and PHMs (patients with BMs located in or within 5 mm around the hippocampus, respectively. In the univariate and multivariate analysis, the number of BMs was the risk factor for HMs and PHMs. Patients with BMs ≥ 5 had significantly higher risk of HMs (odds ratio [OR] 7.892, 95% confidence interval [CI] 1.469-42.404, P = .016, and patients with BMs ≥ 7 had significantly higher risk of PHMs (OR 5.162, 95% CI 2.017-13.213, P = .001. Patients with extracranial metastases are also associated with HMs. CONCLUSIONS: Our results indicate that patients with nonoligometastatic disease are significantly associated with HMs and PHMs. The incidence of PHMs may be acceptably low enough to perform HS-WBRT for SCLC. Our findings provide valuable clinical data to assess the benefit of HS-WBRT in SCLC patients with BMs.

  10. Effects of spike-time-dependent plasticity on the stochastic resonance of small-world neuronal networks

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Haitao; Guo, Xinmeng; Wang, Jiang, E-mail: jiangwang@tju.edu.cn; Deng, Bin; Wei, Xile [School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072 (China)

    2014-09-01

    The phenomenon of stochastic resonance in Newman-Watts small-world neuronal networks is investigated when the strength of synaptic connections between neurons is adaptively adjusted by spike-time-dependent plasticity (STDP). It is shown that irrespective of the synaptic connectivity is fixed or adaptive, the phenomenon of stochastic resonance occurs. The efficiency of network stochastic resonance can be largely enhanced by STDP in the coupling process. Particularly, the resonance for adaptive coupling can reach a much larger value than that for fixed one when the noise intensity is small or intermediate. STDP with dominant depression and small temporal window ratio is more efficient for the transmission of weak external signal in small-world neuronal networks. In addition, we demonstrate that the effect of stochastic resonance can be further improved via fine-tuning of the average coupling strength of the adaptive network. Furthermore, the small-world topology can significantly affect stochastic resonance of excitable neuronal networks. It is found that there exists an optimal probability of adding links by which the noise-induced transmission of weak periodic signal peaks.

  11. Effects of spike-time-dependent plasticity on the stochastic resonance of small-world neuronal networks.

    Science.gov (United States)

    Yu, Haitao; Guo, Xinmeng; Wang, Jiang; Deng, Bin; Wei, Xile

    2014-09-01

    The phenomenon of stochastic resonance in Newman-Watts small-world neuronal networks is investigated when the strength of synaptic connections between neurons is adaptively adjusted by spike-time-dependent plasticity (STDP). It is shown that irrespective of the synaptic connectivity is fixed or adaptive, the phenomenon of stochastic resonance occurs. The efficiency of network stochastic resonance can be largely enhanced by STDP in the coupling process. Particularly, the resonance for adaptive coupling can reach a much larger value than that for fixed one when the noise intensity is small or intermediate. STDP with dominant depression and small temporal window ratio is more efficient for the transmission of weak external signal in small-world neuronal networks. In addition, we demonstrate that the effect of stochastic resonance can be further improved via fine-tuning of the average coupling strength of the adaptive network. Furthermore, the small-world topology can significantly affect stochastic resonance of excitable neuronal networks. It is found that there exists an optimal probability of adding links by which the noise-induced transmission of weak periodic signal peaks.

  12. Outcome and prognostic factors in patients with brain metastases from small-cell lung cancer treated with whole brain radiotherapy.

    Science.gov (United States)

    Bernhardt, Denise; Adeberg, Sebastian; Bozorgmehr, Farastuk; Opfermann, Nils; Hoerner-Rieber, Juliane; König, Laila; Kappes, Jutta; Thomas, Michael; Herth, Felix; Heußel, Claus Peter; Warth, Arne; Debus, Jürgen; Steins, Martin; Rieken, Stefan

    2017-08-01

    The purpose of this study was to evaluate prognostic factors associated with overall survival (OS) and neurological progression free survival (nPFS) in small-cell lung cancer (SCLC) patients with brain metastases who received whole-brain radiotherapy (WBRT). From 2003 to 2015, 229 SCLC patients diagnosed with brain metastases who received WBRT were analyzed retrospectively. In this cohort 219 patients (95%) received a total photon dose of 30 Gy in 10 fractions. The prognostic factors evaluated for OS and nPFS were: age, Karnofsky Performance Status (KPS), number of brain metastases, synchronous versus metachronous disease, initial response to chemotherapy, the Radiation Therapy Oncology Group recursive partitioning analysis (RPA) class and thoracic radiation. Median OS after WBRT was 6 months and the median nPFS after WBRT was 11 months. Patients with synchronous cerebral metastases had a significantly better median OS with 8 months compared to patients with metachronous metastases with a median survival of 3 months (p < 0.0001; HR 0.46; 95% CI 0.31-0.67). Based on RPA classification median survival after WBRT was 17 months in RPA class I, 7 months in class II and 3 months in class III (p < 0.0001). Karnofsky performance status scale (KPS < 70%) was significantly associated with OS in both univariate (HR 2.84; p < 0.001) and multivariate analyses (HR 2.56; p = 0.011). Further, metachronous brain metastases (HR 1.8; p < 0.001), initial response to first-line chemotherapy (HR 0.51, p < 0.001) and RPA class III (HR 2.74; p < 0.001) were significantly associated with OS in univariate analysis. In multivariate analysis metachronous disease (HR 1.89; p < 0.001) and initial response to chemotherapy (HR 0.61; p < 0.001) were further identified as significant prognostic factors. NPFS was negatively significantly influenced by poor KPS (HR 2.56; p = 0.011), higher number of brain metastases (HR 1.97; p = 0.02), and

  13. Robustness of cluster synchronous patterns in small-world networks with inter-cluster co-competition balance

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jianbao [School of Science, Hangzhou Dianzi University, Hangzhou 310018 (China); Ma, Zhongjun, E-mail: mzj1234402@163.com [School of Mathematics and Computing Science, Guilin University of Electronic Technology, Guilin 541004 (China); Chen, Guanrong [Department of Electronic Engineering, City University of Hong Kong, Kowloon, Hong Kong (China)

    2014-06-15

    All edges in the classical Watts and Strogatz's small-world network model are unweighted and cooperative (positive). By introducing competitive (negative) inter-cluster edges and assigning edge weights to mimic more realistic networks, this paper develops a modified model which possesses co-competitive weighted couplings and cluster structures while maintaining the common small-world network properties of small average shortest path lengths and large clustering coefficients. Based on theoretical analysis, it is proved that the new model with inter-cluster co-competition balance has an important dynamical property of robust cluster synchronous pattern formation. More precisely, clusters will neither merge nor split regardless of adding or deleting nodes and edges, under the condition of inter-cluster co-competition balance. Numerical simulations demonstrate the robustness of the model against the increase of the coupling strength and several topological variations.

  14. Surgery Versus Stereotactic Radiosurgery for Single Synchronous Brain Metastasis from Non-Small Cell Lung Cancer

    Institute of Scientific and Technical Information of China (English)

    Hui LI; Sheng-cai HOU; Bin HU; Tong LI; Yang Wang; Jin-bai Miao; Bin You; Yi-li Fu

    2009-01-01

    Objective: The aim of this study is to compare the effectiveness of surgery with stereotactic radiosurgery (SRS) for patients with a single synchronous brain metastasis from successfully treated non-small cell lung cancer.Methods: Between 1995 and 2002, 53 patients underwent resection of both primary non-small cell lung cancer and the associated single brain metastasis. There were 33 men and 20 women with a mean age of 57 years (range, 32(85 years). At the time of diagnosis, 42 patients experienced lung cancer related symptoms, whereas 11 patients experienced brain metastases-related symptoms. 42 patients had received thoracic surgery first, and 11 patients had undergone neurosurgery or radiosurgery first. Pneumonectomy was performed in 9 out of 42 patients (21.4%), lobectomies in 30 (71.4%), and wedge resection in 3 (7.2%). 48 patients (90.5%) underwent complete lymphadenectomy. 35 patients underwent brain metastasectomy. 18 underwent SRS.Results: There was no postoperative mortality and severe complications after either lung or brain surgery. Histology showed 34 adenocarcinomas, 16 squamous cell carcinomas, and 3 large cell lung cancers. 15 patients (28.3%) had no evidence of lymph node metastases (N0), 20 patients (37.7%) had hilar metastases (N1), and 18 patients (34%) had mediastinal metastases (N2). The 1-, 2-, 3- and 5-year overall survival rates were 49%, 19%, 10%, and 5%, respectively. The corresponding data for neurosurgery group were 55%, 17%, 11%, and 6%, respectively. The median survival time was 13 months. For SRS group the corresponding data were 44.8%, 20.9% 10.5%, and 2%, respectively. The median survival time was 14 months. The differences between the two groups were not significant (P>0.05). In lymph node negative patients (N0), the overall 5-year survival rate was 10%, as compared with a 1% survival rate in patients with lymph node metastases (N1(2). The difference was significant (P0.05).Conclusion: Although the overall survival rate for

  15. Global and regional differences in brain anatomy of young children born small for gestational age.

    Directory of Open Access Journals (Sweden)

    Henrica M A De Bie

    Full Text Available In children who are born small for gestational age (SGA, an adverse intrauterine environment has led to underdevelopment of both the body and the brain. The delay in body growth is (partially restored during the first two years in a majority of these children. In addition to a negative influence on these physical parameters, decreased levels of intelligence and cognitive impairments have been described in children born SGA. In this study, we used magnetic resonance imaging to examine brain anatomy in 4- to 7-year-old SGA children with and without complete bodily catch-up growth and compared them to healthy children born appropriate for gestational age. Our findings demonstrate that these children strongly differ on brain organisation when compared with healthy controls relating to both global and regional anatomical differences. Children born SGA displayed reduced cerebral and cerebellar grey and white matter volumes, smaller volumes of subcortical structures and reduced cortical surface area. Regional differences in prefrontal cortical thickness suggest a different development of the cerebral cortex. SGA children with bodily catch-up growth constitute an intermediate between those children without catch-up growth and healthy controls. Therefore, bodily catch-up growth in children born SGA does not implicate full catch-up growth of the brain.

  16. Radiotherapy and systemic chemotherapy for brain metastasis in small cell lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Tada, Takuhito; Minakuchi, Kazuo; Akae, Mayuko [Osaka Prefectural Habikino Hospital (Japan)] [and others

    1997-04-01

    Systemic chemotherapy has been performed for brain metastasis in small cell lung cancer based on the idea that the blood-brain-barrier may not function in the tumor tissue. In order to elucidate the role of radiotherapy and chemotherapy in this situation, a retrospective study was performed. Response rates to radiotherapy and chemotherapy were 55% and 31%, respectively. The median survival times (MST) of radiotherapy alone, chemotherapy alone and combined therapy were 1.6, 4.0 and 6.1 months, respectively, and there were significant differences between radiotherapy alone and combined therapy and between chemotherapy alone and combined therapy. Forty-nine percent of patients who were treated with radiotherapy alone, 63% with chemotherapy alone and 42% with combined therapy died of brain metastasis. The MST of the patients with no prior therapy, relapsed patients whose response to the initial chemotherapy was CR and relapsed patients whose response were PR, were 6.1, 6.1 and 3.3 months, respectively. In the former 2 groups, the presence of brain metastasis is not considered to be a contraindication for chemotherapy. However, chemotherapy should be combined with radiotherapy since relative poor survival and high frequency of death due to tumor were observed when treated with chemotherapy alone, and radiotherapy is considered to be useful as a palliative treatment because of its high response rate and low toxicity. (author)

  17. 阿尔茨海默病患者的大脑功能网络小世界性%Small-worldness of functional networks in Alzheimer's disease

    Institute of Scientific and Technical Information of China (English)

    赵小虎; 王湘彬; 席芊; 江虹; 郭起浩; 刘勇; 王培军

    2012-01-01

    目的 利用静息态血氧水平依赖功能磁共振(BOLD-fMRI)数据,构建大脑功能网络,探讨阿尔茨海默病(AD)患者脑功能网络的小世界属性是否改变.方法 收集2009年1月至2010年6月复旦大学上海医学院附属华山医院神经内科门诊33例AD患者和20名健康老年志愿者参加试验.受试者行简易智能状态检查( MMSE)和Mattis痴呆评定量表(DRS)测试,评估其认知水平.采集静息态BOLD-fMRI数据,计算90个区域之间的相关系数,构建N×N(N =90)的相关性Z值矩阵.检验AD患者和正常老年人大脑网络的小世界属性,通过双样本t检验探索AD患者相关参数变化.结果 行为学结果:AD组和正常对照组MMSE平均分值分别为20.6±2.3、28.2±1.8.AD组和正常对照组DRS平均分值分别为96 ±11、123±14.两组差异均有统计学意义(均P<0.01).在0.1≤Sparsity≤0.4范围内,AD组和正常对照组均符合小世界属性.但AD患者的聚类系数和平均路径长度在所有阈值点均显著大于正常对照组(P<0.05).结论 AD患者的大脑功能网络仍具有小世界属性,但聚类系数和平均路径长度均高于正常人,提示AD患者脑功能网络信息传递能力和脑区之间信息整合能力受损,该发现对从网络角度研究AD病理机制具有重要意义.%Objective To construct the functional networks of human brains by resting-state functional magnetic resonance imaging (fMRI) and examine whether or not the small-world property of functional brain networks changes in patients with Alzheimer disease (AD).Methods A total of 33 AD patients and 20 healthy old volunteers were recruited.Their cognitive functions were evaluated by the minimental state examination (MMSE) and Mattis dementia rating scale (DRS).The resting-state BOLD-fMRI data were acquired and preprocessed. Then the correlation coefficient of every pair of 90 regions was calculated and correlation matrix Z ( N × N,N =90) generated by Fisher Z

  18. Initial investigation of three selective and potent small molecule oxytocin receptor PET ligands in New World monkeys.

    Science.gov (United States)

    Smith, Aaron L; Freeman, Sara M; Barnhart, Todd E; Abbott, David H; Ahlers, Elizabeth O; Kukis, David L; Bales, Karen L; Goodman, Mark M; Young, Larry J

    2016-07-15

    The neuropeptide oxytocin is part of a neuroendocrine system that has physiological effects ranging from ensuring uterine myometrial contractions at parturition and post-partum mammary gland milk ejection to the modulation of neural control of social relationships. This initial study was performed to investigate the potential use of positron emission tomography (PET) for localizing oxytocin receptors in two New World primates. Three biomarkers for PET (1-3) that are known to have high affinity and selectivity for the human oxytocin receptor were investigated in the common marmoset (Callithrix jacchus) via PET imaging. Brain penetration, and uptake in the salivary gland area were both observed with biomarkers 2 and 3. No brain penetration was observed with 1, but uptake was observed more specifically in several peripheral endocrine glands compared to 2 or 3. Biomarker 2, which displayed the best brain penetration of the three biomarkers in the marmoset, was then investigated in the monogamous coppery titi monkey (Callicebus cupreus) in a brain scan and a limited full body scan. No significant brain penetration of 2 was observed in the titi monkey, but significant uptake was observed in various locations throughout the periphery. Metabolism of 2 was suspected to have been significant based upon HPLC analysis of blood draws, but parent compound was still present near the end of the scan. Follow-up investigations will focus on next generation biomarkers bearing improved binding characteristics and brain penetrability as well as investigating tissue in regions where biomarker uptake was observed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Natural Learning for a Connected World: Education, Technology, and the Human Brain

    Science.gov (United States)

    Caine, Renate N.; Caine, Geoffrey

    2011-01-01

    Why do video games fascinate kids so much that they will spend hours pursuing a difficult skill? Why don't they apply this kind of intensity to their schoolwork? These questions are answered by the authors who pioneered brain/mind learning with the publication of "Making Connections: Teaching and the Human Brain". In their new book, "Natural…

  20. Natural Learning for a Connected World: Education, Technology, and the Human Brain

    Science.gov (United States)

    Caine, Renate N.; Caine, Geoffrey

    2011-01-01

    Why do video games fascinate kids so much that they will spend hours pursuing a difficult skill? Why don't they apply this kind of intensity to their schoolwork? These questions are answered by the authors who pioneered brain/mind learning with the publication of "Making Connections: Teaching and the Human Brain". In their new book, "Natural…

  1. Small Schools in a Big World: Thinking about a Wicked Problem

    Science.gov (United States)

    Corbett, Michael; Tinkham, Jennifer

    2014-01-01

    The position of small rural schools is precarious in much of rural Canada today. What is to be done about small schools in rural communities which are often experiencing population decline and aging, economic restructuring, and the loss of employment and services? We argue this issue is a classic "wicked" policy problem. Small schools…

  2. Metabolic and hemodynamic evaluation of brain metastases from small cell lung cancer with positron emission tomography

    DEFF Research Database (Denmark)

    Lassen, U; Andersen, P; Daugaard, G

    1998-01-01

    for studies of metabolic and hemodynamic features. This study was performed to determine regional cerebral metabolic rate of glucose (rCMRglu), regional cerebral blood flow (rCBF), and regional cerebral blood volume (rCBV) in brain metastases from small cell lung cancer and the surrounding brain. Tumor r......CMRglu, rCBF, and rCBV exerted a broad variability, but were higher than the corresponding values in white matter and higher than or similar to those of gray matter. Tumor rCMRglu and rCBF were highly correlated (P metabolic or hemodynamic parameters...... was not observed. Other methods for noninvasive in vivo analysis of tumor hemodynamics are needed, especially for discrimination between tumor necrosis and hypoxia....

  3. THE MANAGEMENT OF BRAIN METASTASES IN NON-SMALL CELL LUNG CANCER

    Directory of Open Access Journals (Sweden)

    Scott eOwen

    2014-09-01

    Full Text Available Brain metastases (BM are a common and lethal complication of non-small cell lung cancer (NSCLC which portend a poor prognosis. In addition, their management implies several challenges including preservation of neurological and neuro-cognitive function during surgery or radiation -therapy, minimizing iatrogenic complications of supportive medications, and optimizing drug delivery across the blood brain barrier (BBB. Despite these challenges, advancements in combined modality approaches can deliver hope of improved overall survival and quality of life for a subset of NSCLC patients with BM. Moreover, new drugs harnessing our greater understanding of tumour biology promise to build on this hope. In this mini-review, we revised the management of BM in NSCLC including advancements in neurosurgery, radiation therapy, as well as systemic and supportive therapy.

  4. [Spectrofluorometric determination of dopamine in small areas of rat brain (author's transl)].

    Science.gov (United States)

    López-Novoa, J M; Martínez-Conde, E; Fraile, A

    1977-03-01

    A method for the extraction and quantification of Dopamine from small areas of rat brain has been developed. The extraction with solvents eliminates the column cromatography separations and allows the simultaneous processing of a good number of samples. Sample retrieval is quite high (70%) and very reproducible. The evaluation was made from areas with a minimal weight of 0.225 g. The quantification of Dopamine was obtained using spectrofluorometric techniques, reading the fluorescence of the trihydroxy indol derivate. The linear relation between the instrument readings and the concentration of Dopamine is from 0 to 0.5 microng/ml. The maximal concentration of Dopamine was found in the decorticated cerebral hemispheres (1.485 microng/g), the next highest values in the diencephalon (1.046 microng/), and the minimal concentration in the cerebellum (0.283 microng/g). The concentration of the whole brain was 0.701 microng/g.

  5. Therapy for non-small-cell lung cancer patients with brain metastasis Therapy for non-small-cell lung cancer patients with brain metastasis

    Institute of Scientific and Technical Information of China (English)

    Bing Li; Yuchen Bao Co-first author; Bin Chen; Songwen Zhou

    2014-01-01

    Brain metastasis is a major cause of poor prognosis and high mortality for non-smal celllung cancer patients. The prognosis of non-smal-celllung cancer (NSCLC) patients with brain metastasis is generaly poor and more efective treatment is required to improve their prognosis. Whole-brain radiotherapy, surgery, stereotactic radiosurgery, chemotherapy and targeted therapy are the main treatment for brain metastasis. This review focuses on the five therapeutic strategy and in particular, on targeted therapy.

  6. Emergence of synchronization induced by the interplay between two prisoner's dilemma games with volunteering in small-world networks

    Science.gov (United States)

    Chen, Yong; Qin, Shao-Meng; Yu, Lianchun; Zhang, Shengli

    2008-03-01

    We studied synchronization between prisoner’s dilemma games with voluntary participation in two Newman-Watts small-world networks. It was found that there are three kinds of synchronization: partial phase synchronization, total phase synchronization, and complete synchronization, for varied coupling factors. Besides, two games can reach complete synchronization for the large enough coupling factor. We also discussed the effect of the coupling factor on the amplitude of oscillation of cooperator density.

  7. Immunohistochemical detection of transgene expression in the brain using small epitope tags

    Directory of Open Access Journals (Sweden)

    Debyser Zeger

    2010-02-01

    Full Text Available Abstract Background In vivo overexpression of proteins is a powerful approach to study their biological function, generate disease models or evaluate gene therapy approaches. In order to investigate an exogenously expressed protein, specific and sensitive detection is essential. Unfortunately, antibodies that allow histological detection of the protein of interest are not always readily available. The use of an epitope tag fused to the protein can circumvent this problem as well as provide the possibility to discriminate endogenous from overexpressed proteins. In order to minimize impact on the bioactivity and biodistribution of the overexpressed protein, preference is given to small tags. Results In the present study, we evaluated several small epitope tags together with corresponding anti-tag antibodies for the detection of overexpressed proteins in rat brain, using eGFP as a reference. We generated several lentiviral vectors encoding eGFP with different N-terminally fused small epitope tags (AU1, flag, 3flag, HA, myc and V5. After confirmation of their functionality in cell culture, we injected these lentiviral vectors stereotactically into the striatum of rats and prepared paraformaldehyde fixed floating sections for immunohistochemical analysis. Using multiple antibodies and antibody dilutions per epitope tag, we extensively assessed the efficiency of several anti-tag antibodies for chromogenic immunohistochemical detection of the epitope tagged eGFPs by determining the proportion of immunoreactivity detected by anti-tag antibodies compared to anti-GFP antibody. Using fluorescence immunohistochemistry and confocal microscopy, we also quantified the proportion of eGFP-positive cells detected by anti-tag antibodies. Our results show that all the examined small epitope tags could be detected by anti-tag antibodies both in cell extracts as well as in vivo, although to varying degrees depending on the tag and antibody used. Using the presented

  8. Local and global synchronization transitions induced by time delays in small-world neuronal networks with chemical synapses.

    Science.gov (United States)

    Yu, Haitao; Wang, Jiang; Du, Jiwei; Deng, Bin; Wei, Xile

    2015-02-01

    Effects of time delay on the local and global synchronization in small-world neuronal networks with chemical synapses are investigated in this paper. Numerical results show that, for both excitatory and inhibitory coupling types, the information transmission delay can always induce synchronization transitions of spiking neurons in small-world networks. In particular, regions of in-phase and out-of-phase synchronization of connected neurons emerge intermittently as the synaptic delay increases. For excitatory coupling, all transitions to spiking synchronization occur approximately at integer multiples of the firing period of individual neurons; while for inhibitory coupling, these transitions appear at the odd multiples of the half of the firing period of neurons. More importantly, the local synchronization transition is more profound than the global synchronization transition, depending on the type of coupling synapse. For excitatory synapses, the local in-phase synchronization observed for some values of the delay also occur at a global scale; while for inhibitory ones, this synchronization, observed at the local scale, disappears at a global scale. Furthermore, the small-world structure can also affect the phase synchronization of neuronal networks. It is demonstrated that increasing the rewiring probability can always improve the global synchronization of neuronal activity, but has little effect on the local synchronization of neighboring neurons.

  9. Control of a specific motor program by a small brain area in zebrafish

    Directory of Open Access Journals (Sweden)

    Otto eFajardo

    2013-04-01

    Full Text Available Complex motor behaviors are thought to be coordinated by networks of brain nuclei that may control different elementary motor programs. Transparent zebrafish larvae offer the opportunity to analyze the functional organization of motor control networks by optical manipulations of neuronal activity during behavior. We examined motor behavior in transgenic larvae expressing channelrhodopsin-2 throughout many neurons in the brain. Wide-field optical stimulation triggered backward and rotating movements caused by the repeated execution of J-turns, a specific motor program that normally occurs during prey capture. Although optically evoked activity was widespread, behavioral responses were highly coordinated and lateralized. 3-D mapping of behavioral responses to local optical stimuli revealed that J-turns can be triggered specifically in the anterior-ventral optic tectum and/or the adjacent pretectum. These results suggest that the execution of J-turns is controlled by a small group of neurons in the midbrain that may act as a command center. The identification of a brain area controlling a defined motor program involved in prey capture is a step towards a comprehensive analysis of neuronal circuits mediating sensorimotor behaviors of zebrafish.

  10. New neurons in aging brains: molecular control by small non-coding RNAs

    Directory of Open Access Journals (Sweden)

    Marijn eSchouten

    2012-02-01

    Full Text Available Adult neurogenesis is a process that continues in the adult and also aging brain. It generates functional neurons from neural stem cells present in specific brain regions. This phenomenon is largely confined to two main regions: the subventricular zone of the lateral ventricle, and the subgranular zone of the dentate gyrus, in the hippocampus. With age, the hippocampus and particularly the dentate gyrus are affected. For instance, adult neurogenesis is decreased with aging, in both the number of proliferating cells as well as their neuronal differentiation, while in parallel an age-associated decline in cognitive performance is often seen. Surprisingly, the synaptogenic potential of adult-born neurons appears unaffected by aging. Therefore, although proliferation, differentiation, survival and synaptogenesis of adult-born new neurons in the dentate gyrus are closely related to each other, they appear differentially regulated with aging. In this review we discuss the crucial role of a novel class of recently discovered regulators of gene expression, i.e. the small non-coding RNAs, in the development of adult neurogenesis from neural stem cells to functionally integrated neurons. In particular, a subgroup of the small non-coding RNAs, the microRNAs, fine-tune many events during adult neurogenesis progression. Moreover, multiple small non-coding RNAs are differentially expressed in the aged hippocampus. This makes small non-coding RNAs appealing candidates to orchestrate, and possibly correct or prevent, the functional alterations in adult neurogenesis and cognition associated with aging. Finally, we briefly summarize observations that link changes in circulating levels of steroid hormones with alterations in adult neurogenesis and subsequent vulnerability to psychopathology in advanced age, and discuss a possible role of microRNAs in stress-associated alterations in adult neurogenesis during aging.

  11. Results of radiation therapy for patients with brain metastases of small-cell lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Takeki; Murakami, Masao; Kuroda, Yasumasa [Tenri Hospital, Nara (Japan)

    1997-08-01

    The results of cranial irradiation for brain metastases (BM) of small cell lung cancer (SCLC) were investigated. Of a total of 67 patients, aged 33 to 80, 47 patients received whole brain irradiation ranging from 30 to 57.6 Gy (mean: 44.3 Gy), and the remaining 20 with localized BM received boost irradiation up to 40-60 Gy (mean: 52.5 Gy) totally on the policy of high dose irradiation. Response to treatment was evaluated by the neurological function (NF) score proposed by Radiation Therapy Oncology Group (RTOG), as well as tumor size on computed tomography (CT) or magnetic resonance imaging (MRI), or both. The results were as follows: improvement of NF in 70%, complete response in 36%, partial response in 51%, no change in 10% and progressive disease in 1%, respectively. Overall survival rates at 1-, and 2-years from the start of cranial irradiation were 26% and 9%, respectively, resulting in a median survival time (MST) of 6.2 months. The patients who already had BM at the diagnosis of lung cancer survived much longer (p<0.01) than those who developed brain metastases after the initial treatment. Five patients with a small BM detected only by MRI had a survival of 12.9 months in MST. Multivariate analysis showed the significant prognostic factors to be a low level of serum lactate dehydrogenase, a primary lesion well-controlled at the time of cranial irradiation and age younger than 62. Our data suggest that high dose irradiation to control BM is necessary to extend survival. (author)

  12. Enhanced Z-LDA for Small Sample Size Training in Brain-Computer Interface Systems

    Directory of Open Access Journals (Sweden)

    Dongrui Gao

    2015-01-01

    Full Text Available Background. Usually the training set of online brain-computer interface (BCI experiment is small. For the small training set, it lacks enough information to deeply train the classifier, resulting in the poor classification performance during online testing. Methods. In this paper, on the basis of Z-LDA, we further calculate the classification probability of Z-LDA and then use it to select the reliable samples from the testing set to enlarge the training set, aiming to mine the additional information from testing set to adjust the biased classification boundary obtained from the small training set. The proposed approach is an extension of previous Z-LDA and is named enhanced Z-LDA (EZ-LDA. Results. We evaluated the classification performance of LDA, Z-LDA, and EZ-LDA on simulation and real BCI datasets with different sizes of training samples, and classification results showed EZ-LDA achieved the best classification performance. Conclusions. EZ-LDA is promising to deal with the small sample size training problem usually existing in online BCI system.

  13. The remarkable visual capacities of nocturnal insects: vision at the limits with small eyes and tiny brains.

    Science.gov (United States)

    Warrant, Eric J

    2017-04-05

    Nocturnal insects have evolved remarkable visual capacities, despite small eyes and tiny brains. They can see colour, control flight and land, react to faint movements in their environment, navigate using dim celestial cues and find their way home after a long and tortuous foraging trip using learned visual landmarks. These impressive visual abilities occur at light levels when only a trickle of photons are being absorbed by each photoreceptor, begging the question of how the visual system nonetheless generates the reliable signals needed to steer behaviour. In this review, I attempt to provide an answer to this question. Part of the answer lies in their compound eyes, which maximize light capture. Part lies in the slow responses and high gains of their photoreceptors, which improve the reliability of visual signals. And a very large part lies in the spatial and temporal summation of these signals in the optic lobe, a strategy that substantially enhances contrast sensitivity in dim light and allows nocturnal insects to see a brighter world, albeit a slower and coarser one. What is abundantly clear, however, is that during their evolution insects have overcome several serious potential visual limitations, endowing them with truly extraordinary night vision.This article is part of the themed issue 'Vision in dim light'.

  14. Coping with the World: Tools of Pragmatism : Mind, Brain, and the Intentional Vocabulary

    OpenAIRE

    Krabberød, Anders Kristian

    2004-01-01

    In this paper I explore the tension that arises when we describe ourselves as intentional beings, on one side, and biological or physical beings on the other. That is, I take a closer look at the age old problem of how the mind relates to the brain. In order to get a better grip on the tension between mental and physical descriptions I start of the discussion with a closer look at what it means to explain the same object, the brain, as two different kinds of thing. The pragmatic kind of natur...

  15. GATE simulation of a new design of pinhole SPECT system for small animal brain imaging

    Science.gov (United States)

    Uzun Ozsahin, D.; Bläckberg, L.; El Fakhri, G.; Sabet, H.

    2017-01-01

    Small animal SPECT imaging has gained an increased interest over the past decade since it is an excellent tool for developing new drugs and tracers. Therefore, there is a huge effort on the development of cost-effective SPECT detectors with high capabilities. The aim of this study is to simulate the performance characteristics of new designs for a cost effective, stationary SPECT system dedicated to small animal imaging with a focus on mice brain. The conceptual design of this SPECT system platform, Stationary Small Animal SSA-SPECT, is to use many pixelated CsI:TI detector modules with 0.4 mm × 0.4 mm pixels in order to achieve excellent intrinsic detector resolution where each module is backed by a single pinhole collimator with 0.3 mm hole diameter. In this work, we present the simulation results of four variations of the SSA-SPECT platform where the number of detector modules and FOV size is varied while keeping the detector size and collimator hole size constant. Using the NEMA NU-4 protocol, we performed spatial resolution, sensitivity, image quality simulations followed by a Derenzo-like phantom evaluation. The results suggest that all four SSA-SPECT systems can provide better than 0.063% system sensitivity and < 1.5 mm FWHM spatial resolution without resolution recovery or other correction techniques. Specifically, SSA-SPECT-1 showed a system sensitivity of 0.09% in combination with 1.1 mm FWHM spatial resolution.

  16. The growing world of small heat shock proteins : from structure to functions

    NARCIS (Netherlands)

    Carra, Serena; Alberti, Simon; Arrigo, Patrick A; Benesch, Justin L; Benjamin, Ivor J; Boelens, Wilbert; Bartelt-Kirbach, Britta; Brundel, Bianca J J M; Buchner, Johannes; Bukau, Bernd; Carver, John A; Ecroyd, Heath; Emanuelsson, Cecilia; Finet, Stephanie; Golenhofen, Nikola; Goloubinoff, Pierre; Gusev, Nikolai; Haslbeck, Martin; Hightower, Lawrence E; Kampinga, Harm H; Klevit, Rachel E; Liberek, Krzysztof; Mchaourab, Hassane S; McMenimen, Kathryn A; Poletti, Angelo; Quinlan, Roy; Strelkov, Sergei V; Toth, Melinda E; Vierling, Elizabeth; Tanguay, Robert M

    2017-01-01

    Small heat shock proteins (sHSPs) are present in all kingdoms of life and play fundamental roles in cell biology. sHSPs are key components of the cellular protein quality control system, acting as the first line of defense against conditions that affect protein homeostasis and proteome stability,

  17. Impact of Partial Time Delay on Temporal Dynamics of Watts-Strogatz Small-World Neuronal Networks

    Science.gov (United States)

    Yan, Hao; Sun, Xiaojuan

    2017-06-01

    In this paper, we mainly discuss effects of partial time delay on temporal dynamics of Watts-Strogatz (WS) small-world neuronal networks by controlling two parameters. One is the time delay τ and the other is the probability of partial time delay pdelay. Temporal dynamics of WS small-world neuronal networks are discussed with the aid of temporal coherence and mean firing rate. With the obtained simulation results, it is revealed that for small time delay τ, the probability pdelay could weaken temporal coherence and increase mean firing rate of neuronal networks, which indicates that it could improve neuronal firings of the neuronal networks while destroying firing regularity. For large time delay τ, temporal coherence and mean firing rate do not have great changes with respect to pdelay. Time delay τ always has great influence on both temporal coherence and mean firing rate no matter what is the value of pdelay. Moreover, with the analysis of spike trains and histograms of interspike intervals of neurons inside neuronal networks, it is found that the effects of partial time delays on temporal coherence and mean firing rate could be the result of locking between the period of neuronal firing activities and the value of time delay τ. In brief, partial time delay could have great influence on temporal dynamics of the neuronal networks.

  18. [Brain injury: existential view to the restoration of the patient's contact with the self and the world].

    Science.gov (United States)

    Ignatieva, N S

    2014-01-01

    We present conceptual changes in psychological rehabilitation after severe brain injury. Traditional clinical approach reduces the person's inner life to level of consciousness, considers psychological processes only from the deficit point of view. We consider the experience of coming out of coma (non-existence) from the point of fundamental components of existence, i.e. anchoring with the world, with life, with self, with the future (Langle, 2003). In aspect of experience these components form the matrix of Patient-World and Patient-Self recovery phases. While working with BI patients, we have defined following phases: 0-phase: experiencing existence, the feeling "I exist here". The main target of psychotherapy is consolidation and reinforcement of the feeling of existence through the feeling of one's body boundaries (and extension), and finding resources for surviving. 1-phase: "be-able-to-exist-in-the world". The patient comes across reality of external world. We mean first of all the perception of the factual side of the world. 2-phase: loving life. The work is concentrated on the recovery of patient's ability to address himself and others so as to be able to experience emotions and live through his own wishes. 3-phase: restoration of patient's self-image and substantiation of own value. It means self-perception and selfrespect despite all the losses and deficits because of trauma. 4-phase: finding the sense. It is necessary to help the patient to make the existential change to avoid dependent position, don't consider himself as the victim of circumstances. This conception is used on different stages of recovery starting from severe disordered consciousness to socialization stage.

  19. Brain delivery of small interfering ribonucleic acid and drugs through intranasal administration with nano-sized polymer micelles

    Directory of Open Access Journals (Sweden)

    Kanazawa T

    2015-01-01

    Full Text Available Takanori Kanazawa School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan Abstract: Recently, the development of effective strategies for enhancing drug delivery to the brain has been a topic of great interest in both clinical and pharmaceutical fields. In this review, we summarize our studies evaluating nose-to-brain delivery of drugs and small interfering ribonucleic acids in combination with cell-penetrating peptide-modified polymer micelles. Our findings show that the use of polymer micelles with surface modification with Tat peptide in the intranasal administration enables the non-invasive delivery of therapeutic agents to the brain by increasing the transfer of the administered drug or small interfering ribonucleic acid to the central nervous system from the nasal cavity. Keywords: nose-to-brain, polymer micelles, cell-penetrating peptide, intranasal administration, nucleic acid

  20. Specific Regional and Age-Related Small Noncoding RNA Expression Patterns Within Superior Temporal Gyrus of Typical Human Brains Are Less Distinct in Autism Brains

    Science.gov (United States)

    Stamova, Boryana; Ander, Bradley P.; Barger, Nicole; Sharp, Frank R.

    2015-01-01

    Small noncoding RNAs play a critical role in regulating messenger RNA throughout brain development and when altered could have profound effects leading to disorders such as autism spectrum disorders (ASD). We assessed small noncoding RNAs, including microRNA and small nucleolar RNA, in superior temporal sulcus association cortex and primary auditory cortex in typical and ASD brains from early childhood to adulthood. Typical small noncoding RNA expression profiles were less distinct in ASD, both between regions and changes with age. Typical micro-RNA coexpression associations were absent in ASD brains. miR-132, miR-103, and miR-320 micro-RNAs were dysregulated in ASD and have previously been associated with autism spectrum disorders. These diminished region- and age-related micro-RNA expression profiles are in line with previously reported findings of attenuated messenger RNA and long noncoding RNA in ASD brain. This study demonstrates alterations in superior temporal sulcus in ASD, a region implicated in social impairment, and is the first to demonstrate molecular alterations in the primary auditory cortex. PMID:26350727

  1. Towards Practical Brain-Computer Interfaces Bridging the Gap from Research to Real-World Applications

    CERN Document Server

    Dunne, Stephen; Leeb, Robert; Millán, José; Nijholt, Anton

    2013-01-01

    Brain-computer interfaces (BCIs) are devices that enable people to communicate via thought alone. Brain signals can be directly translated into messages or commands. Until recently, these devices were used primarily to help people who could not move. However, BCIs are now becoming practical tools for a wide variety of people, in many different situations. What will BCIs in the future be like? Who will use them, and why? This book, written by many of the top BCI researchers and developers, reviews the latest progress in the different components of BCIs. Chapters also discuss practical issues in an emerging BCI enabled community. The book is intended both for professionals and for interested laypeople who are not experts in BCI research.

  2. The world can look better: enhancing beauty experience with brain stimulation

    Science.gov (United States)

    Lega, Carlotta; Flexas, Albert; Nadal, Marcos; Munar, Enric; Cela-Conde, Camilo J.

    2014-01-01

    Aesthetic appreciation is part of our everyday life: it is a subjective judgment we make when looking at a painting, a landscape, or—in fact—at another person. Neuroimaging and electrophysiological evidence suggests that the left dorsolateral prefrontal cortex (DLPFC) plays a critical role in aesthetic judgments. Here, we show that the experience of beauty can be artificially enhanced with brain stimulation. Specifically, we show that aesthetic appreciation of representational paintings and photographs can be increased by applying anodal (excitatory) transcranial direct current stimulation on the left DLPFC. Our results thus show that beauty is in the brain of the beholder, and offer a novel view on the neural networks underlying aesthetic appreciation. PMID:24132459

  3. The world can look better: enhancing beauty experience with brain stimulation.

    Science.gov (United States)

    Cattaneo, Zaira; Lega, Carlotta; Flexas, Albert; Nadal, Marcos; Munar, Enric; Cela-Conde, Camilo J

    2014-11-01

    Aesthetic appreciation is part of our everyday life: it is a subjective judgment we make when looking at a painting, a landscape, or--in fact--at another person. Neuroimaging and electrophysiological evidence suggests that the left dorsolateral prefrontal cortex (DLPFC) plays a critical role in aesthetic judgments. Here, we show that the experience of beauty can be artificially enhanced with brain stimulation. Specifically, we show that aesthetic appreciation of representational paintings and photographs can be increased by applying anodal (excitatory) transcranial direct current stimulation on the left DLPFC. Our results thus show that beauty is in the brain of the beholder, and offer a novel view on the neural networks underlying aesthetic appreciation.

  4. Pulsatile crizotinib treatment for brain metastasis in a patient with non-small-cell lung cancer.

    Science.gov (United States)

    Wang, S; Chen, J; Xie, Z; Xia, L; Luo, W; Li, J; Li, Q; Yang, Z

    2017-10-01

    Anaplastic lymphoma kinase (ALK)-rearranged non-small-cell lung cancer (NSCLC) is a distinct subtype with patients showing peculiar clinicopathological features and dramatic responses to the ALK tyrosine kinase inhibitor crizotinib. Patients with this cancer variant have a dismal prognosis and limited treatment options when it has progressed to intracranial metastasis because of inadequate drug penetration into the central nervous system (CNS). Factors associated with response to TKI therapy have been reported to include pharmacokinetic and biodynamic resistance phenomena. In our NSCLC patient with multiple intracranial metastases, we administered high-dose pulsatile crizotinib therapy (1000 mg/d) on a one-day-on/one-day-off basis. A significant central nervous system (CNS) response was achieved, and time to neurological progression was prolonged to 6 months. High-dose pulsatile therapy may be an effective dosing strategy for crizotinib in NSCLC showing progression to metastasis in the brain. © 2017 John Wiley & Sons Ltd.

  5. Memory Self-Efficacy Beliefs Modulate Brain Activity when Encoding Real-World Future Intentions

    OpenAIRE

    2013-01-01

    Background: While the use of different cognitive strategies when encoding episodic memory information has been extensively investigated, modulation of brain activity by memory self-efficacy beliefs has not been studied yet. Methodology/Principal Findings: Sixteen young adults completed the prospective and retrospective metamemory questionnaire, providing individual subjective judgments of everyday memory function. The day after, using functional magnetic resonance imaging, the participants ha...

  6. Riley-Day syndrome, brain stimulation and the genetic engineering of a world without pain.

    Science.gov (United States)

    Mancini, L S

    1990-03-01

    Riley-Day Syndrome, a genetic disorder in which there is impaired ability or inability to feel pain, hot and cold, is cited as an example of evidence that the commonplace notion that life cannot be painless is not necessarily valid. A hypothesis is presented to the effect that everything adaptive which is achievable with a mind capable of experiencing varying degrees of both pleasure and pain (the human condition as we know it) could be achieved with a mind capable of experiencing only varying degrees of pleasure. Two possible approaches whereby the human mind could be rendered painless are a schematically-outlined genetic approach, which would or will probably take thousands of years to implement, and a brain stimulation approach that could be effected by means of a noninvasive, contactless, transcranial, deep-neuroanatomic-site-focusable, electromagnetic and/or ultrasonic (and/or, conceivably, other kind of) brain pacemaker which could be developed within a few years. In order to expedite the relief of all kinds of suffering and the improvement of the human condition in general, it is advocated that prompt and concerted research effort be directed toward the development of such a brain pacemaker.

  7. Nonlinear Dynamical Behavior in BS Evolution Model Based on Small-World Network Added with Nonlinear Preference

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ying-Yue; YANG Qiu-Ying; CHEN Tian-Lun

    2007-01-01

    We introduce a modified small-world network adding new links with nonlinearly preferential connection instead of adding randomly, then we apply Bak-Sneppen (BS) evolution model on this network. We study several important structural properties of our network such as the distribution of link-degree, the maximum link-degree, and the length of the shortest path. We further argue several dynamical characteristics of the model such as the important critical value fc, the f0 avalanche, and the mutating condition, and find that those characteristics show particular behaviors.

  8. Multistage Random Growing Small-World Networks with Power-Law Degree Distribution

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-Guo; DANG Yan-Zhong; WANG Zhong-Tuo

    2006-01-01

    @@ We present a simple rule which could generate scale-free networks with very large clustering coefficient and very small average distance. These networks, called the multistage random growing networks (MRGNs), are constructed by a two-stage adding process for each new node. The analytic results of the power-law exponentγ = 3 and the clustering coefficient C = 0.81 are obtained, which agree with the simulation results approximately.

  9. CMUNITED-97: RoboCup-97 Small-Robot World Champion Team

    OpenAIRE

    Veloso, Manuela M.; Stone, Peter; Han, Kwun

    1998-01-01

    Robotic soccer is a challenging research domain that involves multiple agents that need to collaborate in an adversarial environment to achieve specific objectives. In this article, we describe CMUNITED, the team of small robotic agents that we developed to enter the RoboCup-97 competition. We designed and built the robotic agents, devised the appropriate vision algorithm, and developed and implemented algorithms for strategic collaboration between the robots in an uncertain and dynamic envir...

  10. Local rewiring algorithms to increase clustering and grow a small world

    CERN Document Server

    Alstott, Jeff; Pizza, Pamela B; Radcliffe, Mary

    2016-01-01

    Many real-world networks have high clustering among vertices: vertices that share neighbors are often also directly connected to each other. A network's clustering can be a useful indicator of its connectedness and community structure. Algorithms for generating networks with high clustering have been developed, but typically rely on adding or removing edges and nodes, sometimes from a completely empty network. Here, we introduce algorithms that create a highly clustered network by starting with an existing network and rearranging edges, without adding or removing them; these algorithms can preserve other network properties even as the clustering increases. These algorithms rely on local rewiring rules, in which a single edge changes one of its vertices in a way that is guaranteed to increase clustering. This greedy algorithm can be applied iteratively to transform a random network into a form with much higher clustering. Additionally, these algorithms grow the network's clustering faster than they increase it...

  11. Developing Science: Scientific Performance and Brain Drains in the Developing World.

    Science.gov (United States)

    Weinberg, Bruce A

    2011-05-01

    Establishing a strong scientific community is important as countries develop, which requires both producing and retaining of important scientists. We show that developing countries produce a sizeable number of important scientists, but that they experience a tremendous brain drain. Education levels, population, and per capita GDP are positively related to the number of important scientists born in and staying in a country. Our analysis indicates that democracy and urbanization are associated with the production of more important scientists although democracy is associated with more out-migration.

  12. Berlin, Maryland - How One Small City is Using Science to Change its World

    Science.gov (United States)

    Allen, L.; Silbergeld, E.

    2016-12-01

    Small cities are uniquely challenged to mitigate environmental issues in their communities because they usually lack the financial resources and technical expertise to address them. The Town of Berlin, population 4,500, recently purchased approximately 60 acres of private property located at 9943 Old Ocean City Boulevard. The property was previously owned by Tyson Chicken, Inc. and contains a chicken processing plant which has not been in use for over 10 years. Historically the plant emitted significant odors which limited the Town's ability to diversify its economic base. The plant closure provided an opportunity to convert the property to another use, but the downturn in the economy delayed that change. The Town intends to establish recreation oriented uses on the property with the following goals in mind: Create a common ground for the people of Berlin that will unite various neighborhoods. Create synergy between ecological sustainability and community resilience Upgrade the ponds on the property to make them the design focal point Through the Thriving Earth Exchange, the Town of Berlin connected with Dr. Ellen Silbergeld to resolve the question of how to remediate the ponds. Dr. Silbergeld is trained as an environmental engineer and public health researcher, with substantial experience in environmental issues in the poultry industry. This case study will show how one small city is working with a volunteer scientist to convert a blighted piece of property into a multi-use public space for the benefit of its residents and guests.

  13. Retinal structure assessed by OCT as a biomarker of brain development in children born small for gestational age.

    Science.gov (United States)

    Pueyo, Victoria; Pérez, Teresa; González, Inmaculada; Altemir, Irene; Gimenez, Galadriel; Prieto, Esther; Paules, Cristina; Oros, Daniel; Lopez-Pison, Javier; Fayed, Nicolás; Garcia-Martí, Gracián; Sanz-Requena, Roberto; Marin, Miguel Angel

    2017-09-01

    To identify differences in neuronal tissue from retinal and brain structures in children born small for gestational age (SGA) with no abnormality in neonatal brain ultrasonography and no previous neurological impairment, and to evaluate the relationship between retinal structure and brain changes in school-age children born SGA. Two cohorts of children were recruited: 25 children born SGA and 25 children born with an appropriate birth weight according to gestational age. All the children underwent an ophthalmic examination, which included retinal imaging using spectral-domain optical coherence tomography, and a brain MRI. MRI images were automatically segmented and global and regional brain volumes were obtained. Although visual function did not differ between both groups, the complex ganglion cell and inner plexiform layers (GCL-IPL) was thinner in SGA children. Total intracranial volume, and global grey and white matter volumes in brain and cerebellum were correlated with birthweight centile, as were certain regional volumes (temporal and parietal lobes, hippocampus and putamen). Abnormal GCL-IPL measurements accurately identified SGA children with the most severe grey and white matter changes in the brain. SGA children, both preterm and term born, showed evidence of structural abnormalities in the retina, which may be an accurate and non-invasive biomarker of neuronal damage in brain tissue. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  14. Small-Town Touch, Big-City Innovation, World-Class Aspirations.

    Science.gov (United States)

    Forgey, Warren L; Dye, Tammy

    2015-01-01

    The healthcare system in the United States is at a critical crossroads. Costs are rising, measures of healthcare quality are well below those of other industrialized nations, and public and regulatory scrutiny is increasing. Healthcare leaders are searching for more effective, efficient, and sustainable operational models to address the mounting challenges they face. We at Schneck Medical Center in Seymour, Indiana, chose the Baldrige Excellence Framework to guide our organization, to accelerate our performance improvement journey, and to create sustainable results in our core services. The Baldrige Framework uses a systematic approach to innovation and improvement in seven key management areas. These seven areas were leadership; strategic planning; customer focus; measurement, analysis, and knowl- edge management; workforce focus; operations focus; and results (Baldrige Performance Excellence Program 2015). In this article, we describe our Baldrige journey. We address why we chose to use the Framework, how we engaged our key stakeholders, and what challenges we faced and lessons we learned along the way. In addition, we detail how Schneck's focus on performance improvement has resulted in significant returns to the organization. Throughout the article, we refer to our pursuit of performance excellence as a "journey," and it is indeed just that. Quality improvement takes time, because it is a transformation with many steps. World-class performance is attainable only with years of work and constant refinement.

  15. Mean field dynamics of graphs I: Evolution of probabilistic cellular automata for random and small-world graphs

    CERN Document Server

    Waldorp, Lourens J

    2016-01-01

    It was recently shown how graphs can be used to provide descriptions of psychopathologies, where symptoms of, say, depression, affect each other and certain configurations determine whether someone could fall into a sudden depression. To analyse changes over time and characterise possible future behaviour is rather difficult for large graphs. We describe the dynamics of networks using one-dimensional discrete time dynamical systems theory obtained from a mean field approach to (elementary) probabilistic cellular automata (PCA). Often the mean field approach is used on a regular graph (a grid or torus) where each node has the same number of edges and the same probability of becoming active. We show that we can use variations of the mean field of the grid to describe the dynamics of the PCA on a random and small-world graph. Bifurcation diagrams for the mean field of the grid, random, and small-world graphs indicate possible phase transitions for certain parameter settings. Extensive simulations indicate for di...

  16. Dawn arrives at Ceres: Exploration of a small, volatile-rich world

    Science.gov (United States)

    Russell, C. T.; Raymond, C. A.; Ammannito, E.; Buczkowski, D. L.; De Sanctis, M. C.; Hiesinger, H.; Jaumann, R.; Konopliv, A. S.; McSween, H. Y.; Nathues, A.; Park, R. S.; Pieters, C. M.; Prettyman, T. H.; McCord, T. B.; McFadden, L. A.; Mottola, S.; Zuber, M. T.; Joy, S. P.; Polanskey, C.; Rayman, M. D.; Castillo-Rogez, J. C.; Chi, P. J.; Combe, J. P.; Ermakov, A.; Fu, R. R.; Hoffmann, M.; Jia, Y. D.; King, S. D.; Lawrence, D. J.; Li, J.-Y.; Marchi, S.; Preusker, F.; Roatsch, T.; Ruesch, O.; Schenk, P.; Villarreal, M. N.; Yamashita, N.

    2016-09-01

    On 6 March 2015, Dawn arrived at Ceres to find a dark, desiccated surface punctuated by small, bright areas. Parts of Ceres’ surface are heavily cratered, but the largest expected craters are absent. Ceres appears gravitationally relaxed at only the longest wavelengths, implying a mechanically strong lithosphere with a weaker deep interior. Ceres’ dry exterior displays hydroxylated silicates, including ammoniated clays of endogenous origin. The possibility of abundant volatiles at depth is supported by geomorphologic features such as flat crater floors with pits, lobate flows of materials, and a singular mountain that appears to be an extrusive cryovolcanic dome. On one occasion, Ceres temporarily interacted with the solar wind, producing a bow shock accelerating electrons to energies of tens of kilovolts.

  17. CHC: A Robust P2P Overlay Network with Simple Routing and Small-World Features

    Directory of Open Access Journals (Sweden)

    Wenjun Xiao

    2011-08-01

    Full Text Available Almost all recent researches on P2P systems focus on howto build a highly usable P2P overlay network. Researchersinclude small routing table, short query path and goodrobustness into their design objectives of overlay topology. Inthis paper, we present a general group theory method anddefine a new Cayley graph. Based on this Cayley graph, wepropose a novel P2P overlay network called CHC, which hassimple routing (searching scheme and many other excellentproperties such as short query path, high clustering and goodrobustness because of its symmetry. The performance isevaluated by simulation to show that CHC possesses shorterquery path length and higher clustering and better robustnessthan several popular P2P overlay networks such as Chord andUlysses.

  18. Quantitative analysis of L-SPECT system for small animal brain imaging

    Science.gov (United States)

    Rahman, Tasneem; Tahtali, Murat; Pickering, Mark R.

    2016-03-01

    This paper aims to investigate the performance of a newly proposed L-SPECT system for small animal brain imaging. The L-SPECT system consists of an array of 100 × 100 micro range diameter pinholes. The proposed detector module has a 48 mm by 48 mm active area and the system is based on a pixelated array of NaI crystals (10×10×10 mm elements) coupled with an array of position sensitive photomultiplier tubes (PSPMTs). The performance of this system was evaluated with pinhole radii of 50 μm, 60 μm and 100 μm. Monte Carlo simulation studies using the Geant4 Application for Tomographic Emission (GATE) software package validate the performance of this novel dual head L-SPECT system where a geometric mouse phantom is used to investigate its performance. All SPECT data were obtained using 120 projection views from 0° to 360° with a 3° step. Slices were reconstructed using conventional filtered back projection (FBP) algorithm. We have evaluated the quality of the images in terms of spatial resolution (FWHM) based on line spread function, the system sensitivity, the point source response function and the image quality. The sensitivity of our newly proposed L- SPECT system was about 4500 cps/μCi at 6 cm along with excellent full width at half-maximum (FWHM) using 50 μm pinhole aperture at several radii of rotation. The analysis results show the combination of excellent spatial resolution and high detection efficiency over an energy range between 20-160 keV. The results demonstrate that SPECT imaging using a pixelated L-SPECT detector module is applicable in a quantitative study of mouse brain imaging.

  19. Application of Texture Analysis to Study Small Vessel Disease and Blood–Brain Barrier Integrity

    Directory of Open Access Journals (Sweden)

    Maria del C. Valdés Hernández

    2017-07-01

    Full Text Available ObjectivesWe evaluate the alternative use of texture analysis for evaluating the role of blood–brain barrier (BBB in small vessel disease (SVD.MethodsWe used brain magnetic resonance imaging from 204 stroke patients, acquired before and 20 min after intravenous gadolinium administration. We segmented tissues, white matter hyperintensities (WMH and applied validated visual scores. We measured textural features in all tissues pre- and post-contrast and used ANCOVA to evaluate the effect of SVD indicators on the pre-/post-contrast change, Kruskal–Wallis for significance between patient groups and linear mixed models for pre-/post-contrast variations in cerebrospinal fluid (CSF with Fazekas scores.ResultsTextural “homogeneity” increase in normal tissues with higher presence of SVD indicators was consistently more overt than in abnormal tissues. Textural “homogeneity” increased with age, basal ganglia perivascular spaces scores (p < 0.01 and SVD scores (p < 0.05 and was significantly higher in hypertensive patients (p < 0.002 and lacunar stroke (p = 0.04. Hypertension (74% patients, WMH load (median = 1.5 ± 1.6% of intracranial volume, and age (mean = 65.6 years, SD = 11.3 predicted the pre/post-contrast change in normal white matter, WMH, and index stroke lesion. CSF signal increased with increasing SVD post-contrast.ConclusionA consistent general pattern of increasing textural “homogeneity” with increasing SVD and post-contrast change in CSF with increasing WMH suggest that texture analysis may be useful for the study of BBB integrity.

  20. The Biology Of Physics: What The Brain Reveals About Our Understanding Of The Physical World

    Science.gov (United States)

    Dunbar, Kevin Niall

    2009-11-01

    Fundamental concepts in physics such as Newtonian mechanics are surprisingly difficult to learn and discover. Over the past decade have been using an educational neuroscience approach to science education using a combination of ecologically naturalistic situations, classroom settings, and neuroimaging methodologies to investigate the different ways that scientific concepts are invoked or activated in different contexts. In particular, we have sought to determine how networks of brain regions that are highly sensitive to features of the context in which they are used are involved in the use of scientific concepts. We have found that some concepts in physics that are highly tuned to perception are often inhibited in experts (with increased activations in error detection and inhibitory networks of the prefrontal cortex) rather than having undergone a wholesale conceptual reorganization. Other, concepts, such as those involved in perceptual causality can activate highly diverse brain regions, depending on task instructions. For example, when students are shown movies of balls colliding, we find increased activation in the right parietal lobe, yet when the students see the exact same movies and are told that these are positively charged particles repulsing we find increased activations in the temporal lobe that is consistent with the students retrieving semantic information. We also see similar see similar changes in activation patterns in students learning about phase shifts in chemistry classes. A key component of both students and scientists' discourse and reasoning is analogical thinking. Our recent fMRI work indicates that categorization is a key component of this type of reasoning that helps bind superficially different concepts together in the service of reasoning about the causes of unexpected findings. Taken together, these results are allowing us to make insights into the contextually relevant networks of knowledge that are activated during learning. This work

  1. Acute strength exercise and the involvement of small or large muscle mass on plasma brain-derived neurotrophic factor levels

    Directory of Open Access Journals (Sweden)

    Paulo Roberto Correia

    2010-01-01

    Full Text Available OBJECTIVE: Blood neurotrophins, such as the brain-derived neurotrophic factor, are considered to be of great importance in mediating the benefits of physical exercise. In this study, the effect of acute strength exercise and the involvement of small versus large muscle mass on the levels of plasma brain-derived neurotrophic factor were evaluated in healthy individuals. METHODS: The concentric strengths of knee (large and elbow (small flexor and extensor muscles were measured on two separate days. Venous blood samples were obtained from 16 healthy subjects before and after exercise. RESULTS: The levels of brain-derived neurotrophic factor in the plasma did not significantly increase after both arm and leg exercise. There was no significant difference in the plasma levels of the brain-derived neurotrophic factor in the arms and legs. CONCLUSION: The present results demonstrate that acute strength exercise does not induce significant alterations in the levels of brain-derived neurotrophic factor plasma concentrations in healthy individuals. Considering that its levels may be affected by various factors, such as exercise, these findings suggest that the type of exercise program may be a decisive factor in altering peripheral brain-derived neurotrophic factor.

  2. A small world of citations? The influence of collaboration networks on citation practices.

    Directory of Open Access Journals (Sweden)

    Matthew L Wallace

    Full Text Available This paper examines the proximity of authors to those they cite using degrees of separation in a co-author network, essentially using collaboration networks to expand on the notion of self-citations. While the proportion of direct self-citations (including co-authors of both citing and cited papers is relatively constant in time and across specialties in the natural sciences (10% of references and the social sciences (20%, the same cannot be said for citations to authors who are members of the co-author network. Differences between fields and trends over time lie not only in the degree of co-authorship which defines the large-scale topology of the collaboration network, but also in the referencing practices within a given discipline, computed by defining a propensity to cite at a given distance within the collaboration network. Overall, there is little tendency to cite those nearby in the collaboration network, excluding direct self-citations. These results are interpreted in terms of small-scale structure, field-specific citation practices, and the value of local co-author networks for the production of knowledge and for the accumulation of symbolic capital. Given the various levels of integration between co-authors, our findings shed light on the question of the availability of 'arm's length' expert reviewers of grant applications and manuscripts.

  3. Exploration of a Small Volatile-Rich World: New Light on Ceres

    Science.gov (United States)

    Russell, Christopher T.; Raymond, Carol A.; Ammannito, Eleonora; Buczkowski, Debra L.; DeSanctis, Maria Cristina; Hiesinger, Harald; Jaumann, Ralf; McSween, Harry Y.; Nathues, Andreas; Park, Ryan S.; Pieters, Carle M.

    2016-04-01

    In March 2015, Dawn arrived at Ceres after its 7.5-year journey. It had orbited and mapped Vesta before arriving at its final target, the largest body in the main asteroid belt. There it found a dark, dry, heavily cratered surface punctuated by small bright spots. Ceres encountered a similar cratering population to that encountered by Vesta and is just as cratered at smaller sizes, but Ceres is missing the largest expected craters and is gravitationally relaxed at lowest orders. Ceres' crust consists of a thin lag deposit containing ammoniated clay of probable endogenous origin, carbonates and dark material, and exhibits bright patches of possible salt concentrations. To be consistent with the crater distribution and the gravity data, there must exist beneath this crust a strong lithosphere of water-ice and rock, containing carbonates and salt. Under this 'upper mantle' must be a lower mantle, consisting of a warmer, weaker athenosphere of similar chemical composition. In the center lies a solid core. Flat crater floors, flows of material across the surface, isolated mountains at least one of which appears to be an ice volcano, all point to the importance of volatile-driven activity on Ceres that likely involves brine-driven cryovolcanism.

  4. A small world of citations? The influence of collaboration networks on citation practices.

    Science.gov (United States)

    Wallace, Matthew L; Larivière, Vincent; Gingras, Yves

    2012-01-01

    This paper examines the proximity of authors to those they cite using degrees of separation in a co-author network, essentially using collaboration networks to expand on the notion of self-citations. While the proportion of direct self-citations (including co-authors of both citing and cited papers) is relatively constant in time and across specialties in the natural sciences (10% of references) and the social sciences (20%), the same cannot be said for citations to authors who are members of the co-author network. Differences between fields and trends over time lie not only in the degree of co-authorship which defines the large-scale topology of the collaboration network, but also in the referencing practices within a given discipline, computed by defining a propensity to cite at a given distance within the collaboration network. Overall, there is little tendency to cite those nearby in the collaboration network, excluding direct self-citations. These results are interpreted in terms of small-scale structure, field-specific citation practices, and the value of local co-author networks for the production of knowledge and for the accumulation of symbolic capital. Given the various levels of integration between co-authors, our findings shed light on the question of the availability of 'arm's length' expert reviewers of grant applications and manuscripts.

  5. Large footprints in a small world: toward a macroeconomics of scale

    Directory of Open Access Journals (Sweden)

    Ann Dale

    2009-04-01

    Full Text Available The question of scale has been of ongoing interest in the sustainable development discourse, particularly with regard to the size, geographical extent, and complexity of human systems. However, this consideration has not sufficiently informed the practical implementation of sustainable technologies and there remain echoes of historical debates over “small is beautiful” versus “bigger is better” that dominated environmentalism during the 1970s. The complex adaptive nature of social and ecological systems suggests that trying artificially to choose a scale for systems is the wrong approach. A properly managed system should self-organize to a scale that optimizes economic prosperity while respecting ecological limits. For this outcome to occur, however, we argue along the lines of Herman Daly for the effective use of macroeconomic tools. Though the specific form of these tools remains undefined, we draw on complex systems theory to suggest four possible properties based on the concepts of resilience and transformability. These properties are then applied to the food system to demonstrate the self-organization of scale.

  6. Decreased small-world functional network connectivity and clustering across resting state networks in schizophrenia: an fMRI classification tutorial.

    Science.gov (United States)

    Anderson, Ariana; Cohen, Mark S

    2013-01-01

    Functional network connectivity (FNC) is a method of analyzing the temporal relationship of anatomical brain components, comparing the synchronicity between patient groups or conditions. We use functional-connectivity measures between independent components to classify between Schizophrenia patients and healthy controls during resting-state. Connectivity is measured using a variety of graph-theoretic connectivity measures such as graph density, average path length, and small-worldness. The Schizophrenia patients showed significantly less clustering (transitivity) among components than healthy controls (p COBRE dataset of 146 Schizophrenia patients and healthy controls, provided as part of the 1000 Functional Connectomes Project. We demonstrate preprocessing, using independent component analysis (ICA) to nominate networks, computing graph-theoretic connectivity measures, and finally using these connectivity measures to either classify between patient groups or assess between-group differences using formal hypothesis testing. All necessary code is provided for both running command-line FSL preprocessing, and for computing all statistical measures and SVM classification within R. Collectively, this work presents not just findings of diminished FNC among resting-state networks in Schizophrenia, but also a practical connectivity tutorial.

  7. Analysis of Small-World Model to a Tendentious Ring Network%带有倾向性的环状网络Small-World现象的分析

    Institute of Scientific and Technical Information of China (English)

    张帆

    2011-01-01

    一个环状网络可以由马尔科夫链来描述,并且通过求解该马尔科夫链的平均首达时间等指标来描述该网络的特点.一个带有倾向性的环状网络,其上马尔科夫链的平均首达时问解可以被精确求出.带有倾向性的环状网络上的Small-world现象与对称环状网络也有一定的差异.%A ring network can be modeled by a Markov chain and its characteristics can be described by several indicators such as the mean first passage times of the Markov chain. The exact results for a tendentions ring network Markov chain model is provided and the difference of Small-World phenomenon between tendentious ring network and a symmetric one is given.

  8. Evaluation of anesthesia effects on [{sup 18}F]FDG uptake in mouse brain and heart using small animal PET

    Energy Technology Data Exchange (ETDEWEB)

    Toyama, Hiroshi E-mail: htoyama@fujita-hu.ac.jp; Ichise, Masanori; Liow, Jeih-San; Vines, Douglass C.; Seneca, Nicholas M.; Modell, Kendra J.; Seidel, Jurgen; Green, Michael V.; Innis, Robert B

    2004-02-01

    This study evaluates effects of anesthesia on {sup 18}F-FDG (FDG) uptake in mouse brain and heart to establish the basic conditions of small animal PET imaging. Prior to FDG injection, 12 mice were anesthetized with isoflurane gas; 11 mice were anesthetized with an intraperitoneal injection of a ketamine/xylazine mixture; and 11 mice were awake. In isoflurane and ketamine/xylazine conditions, FDG brain uptake (%ID/g) was significantly lower than in controls. Conversely, in the isoflurane condition, %ID/g in heart was significantly higher than in controls, whereas heart uptake in ketamine/xylazine mice was significantly lower. Results suggest that anesthesia impedes FDG uptake in mouse brain and affects FDG uptake in heart; however, the effects in the brain and heart differ depending on the type of anesthesia used.

  9. Assessing Disease and Mortality among Small Cetaceans Stranded at a World Heritage Site in Southern Brazil.

    Directory of Open Access Journals (Sweden)

    Isabela G Domiciano

    Full Text Available Cetaceans are considered environmental sentinels and their health often reflects either anthropogenic or natural spatio-temporal disturbances. This study investigated the pathological findings and mortality of small cetaceans with the aim of detecting hazards and monitoring health trends in a high-biodiversity area. Between 2007 and 2012, 218 stranded cetaceans were recorded on the Paraná coast, southern Brazil. Fifty-seven (26.1% of these animals, including 50 Sotalia guianensis, 2 Pontoporia blainvillei, 2 Stenella frontalis, 1 Stenella longirostris, 1 Tursiops truncatus and 1 Globicephala melas were necropsied and samples were collected for histopathology. Causes of death were determined in 46 of the 57 (80.7% animals and most (30 or 65.2% were ascribed to anthropogenic activities, including fisheries bycatch (28/30 and trauma (2/30. The remaining 16 fatalities were considered natural, and attributed to pneumonia (10/16, emaciation (3/16, septicemia (1/16, neonatal pathology (1/16 and choking via food obstruction (1/16. Irrespective of the cause, bronchointerstitial pneumonia, associated with parasitism, lymphadenitis and membranous glomerulonephritis were common findings among all fatalities. These results suggest, that while anthropogenic activities are a leading cause of cetacean strandings in Paraná, underlying pre-existing diseases may contribute towards deaths. Although the studied area is considered a biosphere reserve by UNESCO, complex anthropogenic and natural interactions might be occurring, increasing cetacean susceptibility to hazards. This study may help facilitate developing an effective conservation plan for coastal cetaceans focusing on reducing fisheries interactions, habitat degradation and pollution as mechanisms for ultimately increasing species resilience.

  10. CARBOPLATIN AS 2ND LINE TREATMENT FOR RECURRENT OR PROGRESSIVE BRAIN METASTASES FROM SMALL-CELL LUNG-CANCER

    NARCIS (Netherlands)

    GROEN, HJM; SMIT, EF; HAAXMAREICHE, H; POSTMUS, PE

    1993-01-01

    Patients with brain metastases from small cell lung cancer (SCLC) have a poor prognosis. Although most patients die from metastatic disease outside the central nervous system, this disabling metastatic site often needs treatment to mitigate the signs and symptoms of intracranial disease. The effect

  11. Quantitative Partitions, Benford's Law, and why the Small is Numerous but the Big is Rare in the World

    CERN Document Server

    Kossovsky, Alex Ely

    2016-01-01

    It is often asked why there are many more small things in the world than big things. Why there are many more poor people than rich people. Why there are more villages than cities, and more cities than metropolitans. Such quantitative preference for the small in real-life physical data sets has a corresponding digital preference known as Benford's Law which predicts that the first digit on the leftmost side of numbers in real-life data is proportioned between all possible 1 to 9 digits approximately as in LOG(1 + 1/digit), so that low digits occur much more frequently than high digits. In this article various quantitative partition models are examined in terms of the quantitative and digital behavior of the resultant set of parts. The universal feature found across all partition models is having many small parts but only very few big parts, while Benford's Law is valid only in some particular partition cases and under certain constraints. Hence another vista of Benford's Law is to view it as a particular subse...

  12. Radiolabeled cetuximab plus whole-brain irradiation (WBI) for the treatment of brain metastases from non-small cell lung cancer (NSCLC)

    Energy Technology Data Exchange (ETDEWEB)

    Rades, Dirk; Nadrowitz, Roger [Dept. of Radiation Oncology, Univ. of Luebeck (Germany); Buchmann, Inga; Meller, Birgit [Section of Nuclear Medicine, Univ. of Luebeck (Germany); Hunold, Peter [Dept. of Radiology, Univ. of Luebeck (Germany); Noack, Frank [Inst. of Pathology, Univ. of Luebeck (Germany); Schild, Steven E. [Dept. of Radiation Oncology, Mayo Clinic, Scottsdale, AZ (United States)

    2010-08-15

    Background and Purpose: The addition of systemic drugs to whole-brain irradiation has not improved the survival of patients with multiple brain metastases, most likely because the agents did not readily cross the blood-brain barrier (BBB). Radiolabeling of cetuximab was performed to investigate whether this antibody crosses the BBB. Case Report: A patient with multiple brain lesions from non-small cell lung cancer was investigated. The largest metastasis (40 x 33 x 27 mm) was selected the reference lesion. On day 1, 200 mg/m{sup 2} cetuximab (0.25% hot and 99.75% cold antibody) were given. On day 3, 200 mg/m{sup 2} cetuximab (cold antibody) were given. Weekly doses of 250 mg/m{sup 2} cetuximab were administered for 3 months. Results: The reference lesion showed enhancement of radiolabeled cetuximab ({sup 123}I-Erbi) on scintigraphy; {sup 123}I-Erbi crossed the BBB and accumulated in the lesion. The reference lesion measured 31 x 22 x 21 mm at 4 months. Enhancement of contrast medium was less pronounced. Conclusion: This is the first demonstration of cetuximab crossing the BBB and accumulating in brain metastasis. (orig.)

  13. Design of a Small Modified Minkowski Fractal Antenna for Passive Deep Brain Stimulation Implants

    Directory of Open Access Journals (Sweden)

    Sara Manafi

    2014-01-01

    Full Text Available A small planar modified Minkowski fractal antenna is designed and simulated in dual frequency bands (2.4 and 5.8 GHz for wireless energy harvesting by deep brain stimulation (DBS devices. The designed antenna, physically being confined inside a miniaturized structure, can efficiently convert the wireless signals in dual ISM frequency bands to the energy source to recharge the DBS battery or power the pulse generator directly. The performance metrics such as the return loss, the specific absorption rate (SAR, and the radiation pattern within skin and muscle-fat-skin tissues are evaluated for the designed antenna. The gain of the proposed antenna is 3.2 dBi at 2.4 GHz and 4.7 dBi at 5.8 GHz; also the averaged SAR of the antenna in human body tissue is found to be well below the legally allowed limit at both frequency bands. The link budget shows the received power at the distance of 25 cm at 2.4 GHz and 5.8 GHz are around 0.4 mW and 0.04 mW, which can empower the DBS implant. The large operational bandwidth, the physical compactness, and the efficiency in wireless signal reception make this antenna suitable in being used in implanted biomedical devices such as DBS pulse generators.

  14. Treatment of brain metastases of small-cell lung cancer : Comparing teniposide and teniposide with whole-brain radiotherapy - A phase III study of the European Organization for the Research and Treatment of Cancer Lung Cancer Cooperative Group

    NARCIS (Netherlands)

    Postmus, PE; Haaxma-Reiche, H; Smit, EF; Groen, HJM; Karnicka, H; Lewinski, T; van Meerbeeck, J; Clerico, M; Gregor, A; Curran, D; Sahmoud, T; Kirkpatrick, A; Giaccone, G

    2000-01-01

    Purpose: Approximately 60% of patients with small-cell lung cancer (SCLC) develop brain metastases, Whole-brain radiotherapy (WBRT) gives symptomatic improvement in more than 50% of these patients. Because brain metastases are a sign of systemic progression, and chemotherapy was found to be

  15. Incentives for academic excellence: sex, money and self-advertising in David Lodge’s Changing Places and Small World

    Directory of Open Access Journals (Sweden)

    Felix Nicolau

    2013-12-01

    Full Text Available The paper will focus on two novels of David Lodge’s trilogy, namely Changing Places. A Tale of Two Campuses and Small World. An Academic Romance. During the 1970’s the university life was profusely sponsored by the state. Consequently, academics travelled extensively and improved their professional expertise by leading tumultuous lives. Thus, the latest theories were intertwined with empirical experiments in hedonistic enterprises. The academic rivalries used to be appeased by parallel satisfactions. The legends of the Holy Grail, the Arthurian Cycle, and the Green Knight constituted ferments of a hermeneutics of fertility imbued with post-structuralist relativization. Interculturality received political implications and, in this way, professors had to assume a social standing. This involvement secured their status of authentic intellectuals, beyond the ivory tower. The research resorts to diverse studies on the campus novel. The main scholars to be quoted are Chris Baldick, Catherine Belsey, Eva Lambertsson Björk, and Elaine Showalter.

  16. Self-organized criticality in cortical assemblies occurs in concurrent scale-free and small-world networks.

    Science.gov (United States)

    Massobrio, Paolo; Pasquale, Valentina; Martinoia, Sergio

    2015-06-01

    The spontaneous activity of cortical networks is characterized by the emergence of different dynamic states. Although several attempts were accomplished to understand the origin of these dynamics, the underlying factors continue to be elusive. In this work, we specifically investigated the interplay between network topology and spontaneous dynamics within the framework of self-organized criticality (SOC). The obtained results support the hypothesis that the emergence of critical states occurs in specific complex network topologies. By combining multi-electrode recordings of spontaneous activity of in vitro cortical assemblies with theoretical models, we demonstrate that different 'connectivity rules' drive the network towards different dynamic states. In particular, scale-free architectures with different degree of small-worldness account better for the variability observed in experimental data, giving rise to different dynamic states. Moreover, in relationship with the balance between excitation and inhibition and percentage of inhibitory hubs, the simulated cortical networks fall in a critical regime.

  17. Criticality governed by the stable renormalization fixed point of the Ising model in the hierarchical small-world network.

    Science.gov (United States)

    Nogawa, Tomoaki; Hasegawa, Takehisa; Nemoto, Koji

    2012-09-01

    We study the Ising model in a hierarchical small-world network by renormalization group analysis and find a phase transition between an ordered phase and a critical phase, which is driven by the coupling strength of the shortcut edges. Unlike ordinary phase transitions, which are related to unstable renormalization fixed points (FPs), the singularity in the ordered phase of the present model is governed by the FP that coincides with the stable FP of the ordered phase. The weak stability of the FP yields peculiar criticalities, including logarithmic behavior. On the other hand, the critical phase is related to a nontrivial FP, which depends on the coupling strength and is continuously connected to the ordered FP at the transition point. We show that this continuity indicates the existence of a finite correlation-length-like quantity inside the critical phase, which diverges upon approaching the transition point.

  18. Deposition, diffusion, and aggregation on small-world networks: a model for nanostructure growth on the defective substrate

    Energy Technology Data Exchange (ETDEWEB)

    Shao Zhigang [Department of Physics, Wuhan University, Wuhan 430072 (China); Zou Xianwu [Department of Physics, Wuhan University, Wuhan 430072 (China)]. E-mail: xwzou@whu.edu.cn; Tan Zhijie [Department of Physics, Wuhan University, Wuhan 430072 (China); Huang Shengyou [Department of Physics, Wuhan University, Wuhan 430072 (China); Jin Zhunzhi [Department of Physics, Wuhan University, Wuhan 430072 (China)

    2004-10-11

    Deposition, diffusion, and aggregation (DDA) on a two-dimensional small-world network have been investigated by computer simulations. This model is characterized by two parameters: the clustering exponent {alpha} and long-range connection rate {phi}. The results show that as {alpha} and {phi} vary there exists a continuous crossover in the fractal dimension Df from 1.65 to 2, which corresponds to the crossover from the DDA pattern to dense one. The change of the aggregation pattern results from the long-range connection in the network, which reduces the effect of screening during the aggregation. With primitive analysis, we obtain the expressions of the fractal dimension Df and the crossover point {alpha}c. These results may be useful to describe the vapor deposition, molecular-beam epitaxy, and similar experiments on defective substrates.

  19. Emergence of Sparsely Synchronized Rhythms and Their Responses to External Stimuli in An Inhomogeneous Small-World Complex Neuronal Network

    CERN Document Server

    Kim, Sang-Yoon

    2016-01-01

    We consider an inhomogeneous small-world network (SWN) composed of inhibitory short-range (SR) and long-range (LR) interneurons. By varying the fraction of LR interneurons $p_{long}$, we investigate the effect of network architecture on emergence of sparsely synchronized rhythms, and make comparison with that in the Watts-Strogatz SWN. Although SR and LR interneurons have the same average in- and out-degrees, their betweenness centralities (characterizing the potentiality in controlling communication between other interneurons) are distinctly different. Hence, in view of the betweenness, SWNs we consider are inhomogeneous, unlike the "canonical" Watts-Strogatz SWN with nearly same betweenness centralities. As $p_{long}$ is increased, the average path length becomes shorter, and the load of communication traffic is less concentrated on LR interneurons, which leads to better efficiency of global communication between interneurons. Eventually, when passing a critical value $p_{long}^{(c)}$ $(\\simeq 0.16)$, spars...

  20. Brain surgery in the bush: adapting techniques and technology to fit the developing world.

    Science.gov (United States)

    Vargas, Jan; Mayegga, Emanuel; Nuwas, Emmanuel; Ellegala, Dilantha B; Kucia, Elisa J; Nicholas, Joyce

    2013-11-01

    The critical shortage of surgical services in many areas of the world has profound effects on local communities. Approximately 11% of global disease burden can be attributed to causes that are surgically treatable. Efforts have been made to recruit professionals from developed nations to compensate for the lack of such expertise. However, this practice has created a cycle of dependency on foreign-trained physicians and the medical tools they bring. Recognition of this problem calls for adaptation of a novel problem-solving approach. This article describes techniques and technology available in east Africa that have been adapted to allow basic and emergency neurosurgery to be performed in the absence of complex medical infrastructure and equipment. Commonplace items found in the local environment can be used to emulate more sophisticated instruments, and community-specific engineering programs can be developed to provide locally produced appropriate technology that promotes independence from Western sources. The local economy benefits from much-needed stimulation when these tools are created locally, and this allows for readily available replacement and repair. More studies are under way to identify problems and implement interventions that are realistic and appropriate for these populations.

  1. Spatiotemporal dynamics on small-world neuronal networks: The roles of two types of time-delayed coupling

    Energy Technology Data Exchange (ETDEWEB)

    Wu Hao; Jiang Huijun [Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Hou Zhonghuai, E-mail: hzhlj@ustc.edu.cn [Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2011-10-15

    Highlights: > We compare neuronal dynamics in dependence on two types of delayed coupling. > Distinct results induced by different delayed coupling can be achieved. > Time delays in type 1 coupling can induce a most spatiotemporal ordered state. > For type 2 coupling, the systems exhibit synchronization transitions with delay. - Abstract: We investigate temporal coherence and spatial synchronization on small-world networks consisting of noisy Terman-Wang (TW) excitable neurons in dependence on two types of time-delayed coupling: {l_brace}x{sub j}(t - {tau}) - x{sub i}(t){r_brace} and {l_brace}x{sub j}(t - {tau}) - x{sub i}(t - {tau}){r_brace}. For the former case, we show that time delay in the coupling can dramatically enhance temporal coherence and spatial synchrony of the noise-induced spike trains. In addition, if the delay time {tau} is tuned to nearly match the intrinsic spike period of the neuronal network, the system dynamics reaches a most ordered state, which is both periodic in time and nearly synchronized in space, demonstrating an interesting resonance phenomenon with delay. For the latter case, however, we cannot achieve a similar spatiotemporal ordered state, but the neuronal dynamics exhibits interesting synchronization transitions with time delay from zigzag fronts of excitations to dynamic clustering anti-phase synchronization (APS), and further to clustered chimera states which have spatially distributed anti-phase coherence separated by incoherence. Furthermore, we also show how these findings are influenced by the change of the noise intensity and the rewiring probability of the small-world networks. Finally, qualitative analysis is given to illustrate the numerical results.

  2. The UNDP/World Bank monitoring program on small scale biomass gasifiers (BTG's experience on tar measurements)

    Energy Technology Data Exchange (ETDEWEB)

    Knoef, H.A.M. [Biomass Technology Group BTG, Enschede (Netherlands)

    2000-07-01

    By the time that small-scale biomass gasifiers were 'rediscovered' and promoted for use in developing countries (1970s), UNDP and the World Bank were well aware of the pitfalls of previous attempts to diffuse decentralized energy technologies. Therefore they decided to initiate a technology assessment programme before endorsing and/or stimulating a widespread gasifier introduction programme in developing countries. On July 1, 1983, the UNDP/WB worldwide Small-scale biomass gasifier monitoring was initiated, which was to {sup c}ollect uniform data on the actual field performance, economics, safety and public acceptability of biomass gasifiers currently operating in developing countries{sup .} For the UNDP/WB program BTG developed a tar measuring protocol which was used at twenty gasifiers worldwide (Indonesia, Philippines, Brazil, Mali, Seychelles, Vanuatu and Burundi). Other parameters monitored include pressure and temperatures at various spots, gasflow, fuel consumption, lubrication oil analyses, gas-composition analyses, emission measurements. The seven year programme showed that most of donor funded projects failed, mainly because there was not sufficient commitment from involved parties. National programs on the utilization of loca available biomass resources mostly failed because the fuel did not suit the requirements of gasifier reactor. In case of proper project design/set-up most of the small scale biomass gasifiers operated without major problems. Examples of such projects are the ones in Balong and Majalengka (Indonesia) Onesua (Vanuatu), Espara Feliz (Brazil) and Dogofiry (Mali). A motivated team of technicians, operators, managers is one the most important items within this respect. Most of the heat gasifiers are installed commercially and are much more successful compared to the subsidized power gasifiers. Local manufactured gasifiers are generally constructed of low quality materials causing frequent technical problems. However, locally

  3. Small-World Effect of Complex Network and Its Application to Protein Folding%复杂网络的小世界影响及其在蛋白质折叠中的运用

    Institute of Scientific and Technical Information of China (English)

    卢全国; 陈定方; 彭华魁; 祖巧红

    2004-01-01

    The famous "six letters" experiment carried out by Milgram demonstrated the existence of small-world effect in a complex network. One vertex tends to be connected to another by a shortest path through network because of the small-world effect. This paper uses the small-world effect to study protein folding pathway.

  4. Prognostic predictors for non-small cell lung cancer patients with brain metastasis after radiotherapy

    Directory of Open Access Journals (Sweden)

    Qiuhong FAN

    2008-06-01

    Full Text Available Background and objective Brain metastasis (BM is often found in the patients with lung cancer. Radiotherapy is regular and effective means of therapy and it aims at palliating symptoms and prolonging survival time. However, now there are different viewpoints on protocols of radiotherapy and prognostic factors. A retrospective analysis is used to evaluate the results of treatment for 82 cases with brain metastasis from non-small cell lung cancer (NSCLC and explore the prognostic factors to establish a prognostic index (PI model. Methods From Feb.1995 to Oct. 2006, 82 patients irradiated for BM from NSCLC, with both complete medical charts and follow-up data available, were eligible for this retrospective analysis. A number of potential factors which might affect prognosis after irradiation were evaluated. The significance of prognostic variables in the survival resulted from both univariate analysis by Kaplan-Meier combining with log-rank test and multivariate Cox regression model. The prognostic index (PI was established based on Cox regression analysis and subgrouping values. Results The follow-up time was 1-120 months. For the entire cohort, the median survival from the start of radiation for BM was 10.5 months, and the actuarial overall survival rate was 50.8%, 23.7% and 5.1% at 0.5, 1 and 2 years respectively. Univariate analysis showed KPS, control of primary tumor, interval from the beginning of diagnostic to BM, extracranial systemic metastasis, counts of lymphocyte and solitary BM were predictors of prognosis. However, in the Cox multivariate analysis, only KPS, control of primary tumor, interval from the beginning of diagnostic to BM and solitary BM were significant prognostic factors. The prognostic index was established based on Cox regression analysis and 82 patients were stratified good, intermediate and poor prognostic sub-groups. The difference of survival rate among 3 subgroups is significant (P<0.001. Conclusion Radiotherapy is

  5. Comparison of computed tomography and radionuclide scanning for detection of brain metastases in small cell lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Crane, J.M.; Nelson, M.J.; Ihde, D.C.; Makuch, R.W.; Glatstein, E.; Zabell, A.; Johnston-Early, A.; Bates, H.R.; Saini, N.; Cohen, M.H.

    1984-09-01

    Neurologic history and examination, radionuclide brain scans (RN), and computed tomographic brain scans (CT) were performed at diagnosis and sequentially in 153 consecutive patients with small cell lung cancer (SCLC) to assess the sensitivity and accuracy of these screening methods and to determine whether the early detection of brain metastases influences survival. CT scans (sensitivity, 98%; positive predictive accuracy, 98%) were superior to RN scans (sensitivity, 71%; positive predictive accuracy, 86%) in patients with or without neurologic signs or symptoms. However, CT scans were positive in only 6% of asymptomatic patients at diagnosis and 13% of asymptomatic patients after systemic therapy. Brain metastases detected by CT scan were the sole site of extensive-stage disease in 6% of patients at diagnosis. Despite the enhanced ability of CT scans to detect asymptomatic lesions, survival after therapeutic cranial irradiation was similar for asymptomatic and symptomatic patients. The results suggest that CT brain scans should be used routinely in SCLC patients with neurologic signs or symptoms, at diagnosis (when treatment decisions are based on stage), and at six-month intervals in patients with prior brain metastases and in whom erratic follow-up is likely.

  6. Collective temporal coherence for subthreshold signal encoding on a stochastic small-world Hodgkin-Huxley neuronal network

    Energy Technology Data Exchange (ETDEWEB)

    Ozer, Mahmut [Zonguldak Karaelmas University, Engineering Faculty, Department of Electrical and Electronics Engineering, 67100 Zonguldak (Turkey); Laboratory of Neurophysics and Physiology, UMR 8119 CNRS, Universite Paris Descartes, 45 rue des Saint-Peres, 75006 Paris (France)], E-mail: mahmutozer2002@yahoo.com; Uzuntarla, Muhammet [Zonguldak Karaelmas University, Engineering Faculty, Department of Electrical and Electronics Engineering, 67100 Zonguldak (Turkey); Kayikcioglu, Temel [Karadeniz Technical University, Department of Electrical and Electronics Engineering, Trabzon (Turkey); Graham, Lyle J. [Laboratory of Neurophysics and Physiology, UMR 8119 CNRS, Universite Paris Descartes, 45 rue des Saint-Peres, 75006 Paris (France)

    2008-10-20

    We study the collective temporal coherence of a small-world network of coupled stochastic Hodgkin-Huxley neurons. Previous reports have shown that network coherence in response to a subthreshold periodic stimulus, thus subthreshold signal encoding, is maximal for a specific range of the fraction of randomly added shortcuts relative to all possible shortcuts, p, added to an initially locally connected network. We investigated this behavior further as a function of channel noise, stimulus frequency and coupling strength. We show that temporal coherence peaks when the frequency of the external stimulus matches that of the intrinsic subthreshold oscillations. We also find that large values of the channel noise, corresponding to small cell sizes, increases coherence for optimal values of the stimulus frequency and the topology parameter p. For smaller values of the channel noise, thus larger cell sizes, network coherence becomes insensitive to these parameters. Finally, the degree of coupling between neurons in the network modulates the sensitivity of coherence to topology, such that for stronger coupling the peak coherence is achieved with fewer added short cuts.

  7. NO-tryptophan: a new small molecule located in the rat brain

    Directory of Open Access Journals (Sweden)

    A. Mangas

    2016-09-01

    Full Text Available A highly specific monoclonal antibody directed against nitric oxide-tryptophan (NO-W with good affinity (10-9 M and specificity was developed. In the rat brain, using an indirect immunoperoxidase technique, cell bodies containing NO-W were exclusively found in the intermediate and dorsal parts of the lateral septal nucleus. No immunoreactive fibres were found in the rat brain. This work reports the first visualization and the morphological characteristics of cell bodies containing NO-W in the mammalian brain. The restricted distribution of NO-W in the rat brain suggests that this molecule could be involved in specific physiological mechanisms. 

  8. NO-tryptophan: a new small molecule located in the rat brain.

    Science.gov (United States)

    Mangas, A; Yajeya, J; González, N; Duleu, S; Geffard, M; Coveñas, R

    2016-09-22

    A highly specific monoclonal antibody directed against nitric oxide-tryptophan (NO-W) with good affinity (10-9 M) and specificity was developed. In the rat brain, using an indirect immunoperoxidase technique, cell bodies containing NO-W were exclusively found in the intermediate and dorsal parts of the lateral septal nucleus. No immunoreactive fibres were found in the rat brain. This work reports the first visualization and the morphological characteristics of cell bodies containing NO-W in the mammalian brain. The restricted distribution of NO-W in the rat brain suggests that this molecule could be involved in specific physiological mechanisms.

  9. SU-E-T-457: Design and Characterization of An Economical 192Ir Hemi-Brain Small Animal Irradiator

    Energy Technology Data Exchange (ETDEWEB)

    Grams, M; Wilson, Z; Sio, T; Beltran, C; Tryggestad, E; Gupta, S; Blackwell, C; McCollough, K; Sarkaria, J; Furutani, K [Mayo Clinic, Rochester, MN (United States)

    2014-06-01

    Purpose: To describe the design and dosimetric characterization of a simple and economical small animal irradiator. Methods: A high dose rate 192Ir brachytherapy source from a commercially available afterloader was used with a 1.3 centimeter thick tungsten collimator to provide sharp beam penumbra suitable for hemi-brain irradiation of mice. The unit is equipped with continuous gas anesthesia to allow robust animal immobilization. Dosimetric characterization of the device was performed with Gafchromic film. The penumbra from the small animal irradiator was compared under similar collimating conditions to the penumbra from 6 MV photons, 6 MeV electrons, and 20 MeV electrons from a linear accelerator as well as 300 kVp photons from an orthovoltage unit and Monte Carlo simulated 90 MeV protons. Results: The tungsten collimator provides a sharp penumbra suitable for hemi-brain irradiation, and dose rates on the order of 200 cGy/minute were achieved. The sharpness of the penumbra attainable with this device compares favorably to those measured experimentally for 6 MV photons, and 6 and 20 MeV electron beams from a linear accelerator. Additionally, the penumbra was comparable to those measured for a 300 kVp orthovoltage beam and a Monte Carlo simulated 90 MeV proton beam. Conclusions: The small animal irradiator described here can be built for under $1,000 and used in conjunction with any commercial brachytherapy afterloader to provide a convenient and cost-effective option for small animal irradiation experiments. The unit offers high dose rate delivery and sharp penumbra, which is ideal for hemi-brain irradiation of mice. With slight modifications to the design, irradiation of sites other than the brain could be accomplished easily. Due to its simplicity and low cost, the apparatus described is an attractive alternative for small animal irradiation experiments requiring a sharp penumbra.

  10. Magnetic-resonance-imaging-coupled broadband near-infrared tomography system for small animal brain studies

    Science.gov (United States)

    Xu, Heng; Springett, Roger; Dehghani, Hamid; Pogue, Brian W.; Paulsen, Keith D.; Dunn, Jeff F.

    2005-04-01

    A novel magnetic-resonance-coupled broadband near-infrared (NIR) tomography system for small animal brain studies is described. Several features of the image formation approach are new in NIR tomography and represent major advances in the path to recovering high-resolution hemoglobin and oxygen saturation images of tissue. The NIR data were broadband and continuous wave and were used along with a second-derivative-based estimation of the path length from water absorption. The path length estimation from water was then used along with the attenuation spectrum to recover absorption and reduced scattering coefficient images at multiple wavelengths and then to recover images of total hemoglobin and oxygen saturation. Going beyond these basics of NIR tomography, software has been developed to allow inclusion of structures derived from MR imaging (MRI) for the external and internal tissue boundaries, thereby improving the accuracy and spatial resolution of the properties in each tissue type. The system has been validated in both tissue-simulating phantoms, with 10% accuracy observed, and in a rat cranium imaging experiment. The latter experiment used variation in inspired oxygen (FiO2) to vary the observed hemoglobin and oxygen saturation images. Quantitative agreement was observed between the changes in deoxyhemoglobin values derived from NIR and the changes predicted with blood-oxygen-level-dependent (BOLD) MRI. This system represents the initial stage in what will likely be a larger role for NIR tomography, coupled to MRI, and illustrates that the technological challenges of using continuous-wave broadband data and inclusion of a priori structural information can be met with careful phantom studies.

  11. Comparison of whole brain radiation therapy and locally limited radiation therapy in the treatment of solitary brain metastases from non-small cell lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Ueki, Keisuke; Matsutani, Masao; Nakamura, Osamu; Tanaka, Yoshiaki [Tokyo Metropolitan Komagome Hospital (Japan)

    1996-06-01

    The benefit and risk of whole brain radiation therapy (WBRT) compared to locally limited radiation therapy was assessed in 61 patients with solitary brain metastases from non-small cell lung cancer without an unresectable active primary lesion or systemic dissemination in the other organs. Twenty-three patients received local irradiation (Group A), and 38 patients received whole brain irradiation with or without local irradiation (Group B). The survival was significantly better in Group A than in Group B (p<0.05), with median survivals of 83.1 and 30.7 weeks, respectively. One-year local recurrence rates were 7% in Group A and 21% in Group B, but the difference was not statistically significant. The 1-year distant recurrence rate was similar at 18%. Radiation-induced dementia occurred in two patients in Group A (8.7%) and seven in Group B (18.4%), but was not statistically significant (p=0.30). There is no obvious benefit and possible disadvantages of WBRT compared to local irradiation for the population of patients investigated in this study. Intraoperative radiation therapy or stereotactic radiosurgery without WBRT should be considered in the patients with solitary brain metastases. (author)

  12. Sequential Change of Hypometabolic Metastasis from Non-small-cell Lung Cancer on Brain FDG-PET/CT

    Energy Technology Data Exchange (ETDEWEB)

    Park, Soon Ah; Yang, Sei Hoon; Yang, Chung Yong; Choi, Keum Ha [Wonkwang Medical Science, Wonkwang University College of Medicine, Iksan (Korea, Republic of)

    2009-10-15

    A 60-year-old woman, who had non-small-cell lung cancer (NSCLC) in left lower lobe underwent brain F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for evaluation of cerebral metastasis. On follow-up FDG-PET/CT, only hypometaolic lesion was detected and progressed in right frontal lobe at 6 months and 10 months, later. Hypermetabolic metastasis was not detected even at last scan time of FDG-PET/CT. Brain MRI showed brain metastasis in right frontal lobe. As might be expected, the physician should take cerebral metastasis into consideration even though there is only hypometabolic change on subsequent FDG-PET/CT in patients with NSCLC.

  13. The -G1245A IGF1 polymorphism is related with small head size and less brain sparing in small for gestational age born children.

    Science.gov (United States)

    Ester, Wietske A; van Meurs, Joyce B; Arends, Nicolette J; Uitterlinden, André G; de Ridder, Maria A; Hokken-Koelega, Anita C

    2009-04-01

    Small for gestational age (SGA) subjects experience pre- and postnatal growth restriction, which might be influenced by polymorphisms in the IGF1 gene. The well-known -841(CA)(n)/192 bp polymorphism has been associated with birth size, cardiovascular disease, and IGF-1 levels, and is in linkage disequilibrium with the -G1245A single nucleotide polymorphism (SNP; rs35767). To associate the -G1245A SNP with head circumference (HC) and brain sparing (a greater head compared with height SDS) in short SGA and SGA catch-up subjects. Gene association study. We studied 635 SGA subjects out of which 439 remained short and 196 had a postnatal height >-2.00 SDS. The -G1245A SNP IGF1 gene polymorphism and head size. All SGA subjects had a postnatal head size below the population mean (-1.01 SDS, P<0.001). Whereas SGA catch-up subjects had a head size that was in proportion with their height, short SGA subjects displayed extensive brain sparing (HC - height: SGA CU: 0.01 versus short SGA: 1.75 SDS, P<0.001). The most severely SGA born subjects had a 0.4 SDS smaller postnatal head size and 0.6 SDS less brain sparing when carrying the -1245 A-allele in contrast to G-allele carriers (P=0.03). The association between the -G1245A SNP and head size remained significant after correction for birth weight and postnatal height SDS (P=0.03). Birth weight, birth length and postnatal height SDS were not related with the - G1245A SNP. The -1245 A-allele of the IGF1 promoter SNP is associated with a small head size and less brain sparing in SGA born subjects and particularly those with the lowest birth weight.

  14. National trends in radiotherapy for brain metastases at time of diagnosis of non-small cell lung cancer.

    Science.gov (United States)

    Trifiletti, Daniel M; Sheehan, Jason P; Grover, Surbhi; Dutta, Sunil W; Rusthoven, Chad G; Kavanagh, Brian D; Sahgal, Arjun; Showalter, Timothy N

    2017-08-31

    To analyze the national trends of patients treated radiotherapy for brain metastases from non-small cell lung cancer (NSCLC) that were found at diagnosis. The National Cancer Database was queried for patients with NSCLC diagnosed from 2004 to 2013 that received brain irradiation for metastases and patients grouped into having had received fractionated brain radiotherapy (5-15 fractions with or without radiosurgery) or intracranial radiosurgery alone (1-5 fractions). Univariable and multivariable (MVA) analyses were performed to investigate factors associated with the receipt of SRS alone, and temporal/regional trends. 47,746 patients met inclusion criteria, of which 42,148 received fractionated brain irradiation (88%) and 5,598 received radiosurgery (12%). 345 patients received fractioned brain irradiation with a radiosurgical boost (0.8%). The utilization of radiosurgery-alone increased over time owing to increases in each radiosurgery modality. On MVA, several factors were associated with increased odds of receiving intracranial radiosurgery-alone over fractionated brain radiotherapy including more recent year of diagnosis, increased median income, eastern U.S. regions, further distance to the hospital, and the receipt of chemotherapy (each p<0.001). Patients of Asian descent were less likely to receive radiosurgery alone (p=0.044). In the management of brain metastases from NSCLC, overall utilization of an intracranial radiosurgery alone treatment strategy has increased over the past decade. Despite this, there appear to be significant geographic variations and disparities remain based on patient income level and race. Further study is needed to define the reasons for these disparities and appropriate actions to mitigate them. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Designing Agricultural Development Projects for the Small Scale Farmers: Some Lessons from the World Bank Assistance Small Holder Oil Palm Development Scheme in Nigeria

    Science.gov (United States)

    Orewa, S. I.

    The study was carried out to investigate farmers reasons for intercropping their oil palm farms with food and other cash crops rather than the sole oil palm planting arrangement specified for participation in the World Bank Assistance Smallholder Oil Palm development project financed during the 1975-83 period. The study was conducted at the Ekuku-Agbor Tree Crop Unit Zone (to the East) and Mosogar Tree Crop Unit Zone (to the Southwest) of the old Bendel State of Nigeria. A total of 35 oil palm farmers were randomly selected from each zone for the study. The study tried to identify the size of oil palm cultivated, types of food and cash crops planted and the proportion consumed and sold and the sufficiency of labour for various farm activities. The study showed that the average oil palm farm size at Ekuku-Agbor zone was smaller (about 1.57 ha) and more fragmented while for Mosogar zone it was 2.28 ha. However a greater percentage (over 65%) of the farms at both locations were within 0.01-2.00 ha farm size range which could be said to be relatively small. The study revealed that among other factors the farmers desire to ensure adequate family food needs which equates to food security and some cash to meet regular family financial needs necessitated their intercropping of the oil palm farms. Others include the need to maximize the returns from the use of labour which they considered a major limiting factor in farm maintenance and to take advantage of the relative high unit price of cassava and its products that prevailed then by cultivating on any available land space including the palm plantations and thereby increasing their farm income.

  16. Compass Cells in the Brain of an Insect Are Sensitive to Novel Events in the Visual World.

    Directory of Open Access Journals (Sweden)

    Tobias Bockhorst

    Full Text Available The central complex of the insect brain comprises a group of neuropils involved in spatial orientation and memory. In fruit flies it mediates place learning based on visual landmarks and houses neurons that encode the orientation for goal-directed locomotion, based on landmarks and self-motion cues for angular path-integration. In desert locusts, the central complex holds a compass-like representation of head directions, based on the polarization pattern of skylight. Through intracellular recordings from immobilized locusts, we investigated whether sky compass neurons of the central complex also represent the position or any salient feature of possible landmarks, in analogy to the observations in flies. Neurons showed strongest responses to the novel appearance of a small moving square, but we found no evidence for a topographic representation of object positions. Responses to an individual square were independent of direction of motion and trajectory, but showed rapid adaptation to successive stimulation, unaffected by changing the direction of motion. Responses reappeared, however, if the moving object changed its trajectory or if it suddenly reversed moving direction against the movement of similar objects that make up a coherent background-flow as induced by ego-motion. Response amplitudes co-varied with the precedent state of dynamic background activity, a phenomenon that has been related to attention-dependent saliency coding in neurons of the mammalian primary visual cortex. The data show that neurons of the central complex of the locust brain are visually bimodal, signaling sky compass direction and the novelty character of moving objects. These response properties might serve to attune compass-aided locomotor control to unexpected events in the environment. The difference to data obtained in fruit flies might relate to differences in the lifestyle of landmark learners (fly and compass navigators (locust, point to the existence of

  17. Time Delay and Long-Range Connection Induced Synchronization Transitions in Newman-Watts Small-World Neuronal Networks

    Science.gov (United States)

    Qian, Yu

    2014-01-01

    The synchronization transitions in Newman-Watts small-world neuronal networks (SWNNs) induced by time delay and long-range connection (LRC) probability have been investigated by synchronization parameter and space-time plots. Four distinct parameter regions, that is, asynchronous region, transition region, synchronous region, and oscillatory region have been discovered at certain LRC probability as time delay is increased. Interestingly, desynchronization is observed in oscillatory region. More importantly, we consider the spatiotemporal patterns obtained in delayed Newman-Watts SWNNs are the competition results between long-range drivings (LRDs) and neighboring interactions. In addition, for moderate time delay, the synchronization of neuronal network can be enhanced remarkably by increasing LRC probability. Furthermore, lag synchronization has been found between weak synchronization and complete synchronization as LRC probability is a little less than 1.0. Finally, the two necessary conditions, moderate time delay and large numbers of LRCs, are exposed explicitly for synchronization in delayed Newman-Watts SWNNs. PMID:24810595

  18. Time delay and long-range connection induced synchronization transitions in Newman-Watts small-world neuronal networks.

    Science.gov (United States)

    Qian, Yu

    2014-01-01

    The synchronization transitions in Newman-Watts small-world neuronal networks (SWNNs) induced by time delay τ and long-range connection (LRC) probability P have been investigated by synchronization parameter and space-time plots. Four distinct parameter regions, that is, asynchronous region, transition region, synchronous region, and oscillatory region have been discovered at certain LRC probability P = 1.0 as time delay is increased. Interestingly, desynchronization is observed in oscillatory region. More importantly, we consider the spatiotemporal patterns obtained in delayed Newman-Watts SWNNs are the competition results between long-range drivings (LRDs) and neighboring interactions. In addition, for moderate time delay, the synchronization of neuronal network can be enhanced remarkably by increasing LRC probability. Furthermore, lag synchronization has been found between weak synchronization and complete synchronization as LRC probability P is a little less than 1.0. Finally, the two necessary conditions, moderate time delay and large numbers of LRCs, are exposed explicitly for synchronization in delayed Newman-Watts SWNNs.

  19. Brain metastasis from non-small cell lung cancer (NSCLC). Prognostic importance of the number of involved extracranial organs

    Energy Technology Data Exchange (ETDEWEB)

    Gerdan, L. [University of Luebeck, Department of Radiation Oncology, Luebeck (Germany); University of Luebeck, Section of Nuclear Medicine, Luebeck (Germany); Segedin, B. [Institute of Oncology, Department of Radiation Oncology, Ljubljana (Slovenia); Nagy, V. [Oncology Institute Ion Ciricuta, Department of Radiotherapy, Cluj-Napoca (Romania); Khoa, M.T. [Hanoi Medical University, Department of Nuclear Medicine, Hanoi (Viet Nam); Bach Mai Hospital, Nuclear Medicine and Oncology Center, Hanoi (Viet Nam); Trang, N.T. [Bach Mai Hospital, Nuclear Medicine and Oncology Center, Hanoi (Viet Nam); Schild, S.E. [Mayo Clinic Scottsdale, Department of Radiation Oncology, Scottsdale, AZ (United States); Rades, D. [University of Luebeck, Department of Radiation Oncology, Luebeck (Germany)

    2014-01-15

    This study investigated the potential prognostic value of the number of involved extracranial organs in patients with brain metastasis from non-small cell lung cancer (NSCLC). A total of 472 patients who received whole-brain radiotherapy (WBRT) alone with 5 x 4 Gy or 10 x 3 Gy for brain metastasis from NSCLC were included in this retrospective study. In addition to the number of involved extracranial organs, 6 further potential prognostic factors were investigated including WBRT regimen, age, gender, Karnofsky Performance Score (KPS), number of brain metastases, and the interval from cancer diagnosis to WBRT. Subgroup analyses were performed for patients with metastatic involvement of one (lung vs. bone vs. other metastasis) and two (lung+bone vs. lung+lymph nodes vs. other combinations) extracranial organs. The survival rates at 6 months of the patients with involvement of 0, 1, 2, 3, and ≥4 extracranial organs were 52, 27, 17, 4, and 14%, respectively (p<0.001). On multivariate analysis, the number of involved extracranial organs remained significant (risk ratio 1.32; 95% confidence interval 1.19-1.46; p<0.001). Age <65 years (p=0.004), KPS ≥70 (p<0.001), and only 1-3 brain metastases (p=0.022) were also significantly associated with survival in the multivariate analysis. In the separate analyses of patients with involvement of one and two extracranial organs, survival was not significantly different based on the pattern of extracranial organ involvement. The number of involved extracranial organs is an independent prognostic factor of survival in patients with brain metastasis from NSCLC, irrespective of the pattern of extracranial organ involvement. (orig.)

  20. Functional brain development in growth-restricted and constitutionally small fetuses: a fetal magnetoencephalography case-control study.

    Science.gov (United States)

    Morin, E C; Schleger, F; Preissl, H; Braendle, J; Eswaran, H; Abele, H; Brucker, S; Kiefer-Schmidt, I

    2015-08-01

    Fetal magnetoencephalography records fetal brain activity non-invasively. Delayed brain responses were reported for fetuses weighing below the tenth percentile. To investigate whether this delay indicates delayed brain maturation resulting from placental insufficiency, this study distinguished two groups of fetuses below the tenth percentile: growth-restricted fetuses with abnormal umbilical artery Doppler velocity (IUGR) and constitutionally small-for-gestational-age fetuses with normal umbilical artery Doppler findings (SGA) were compared with fetuses of adequate weight for gestational age (AGA), matched for age and behavioural state. A case-control study of matched pairs. Fetal magnetoencephalography-Center at the University Hospital of Tuebingen. Fourteen IUGR fetuses and 23 SGA fetuses were matched for gestational age and fetal behavioural state with 37 healthy, normal-sized fetuses. A 156-channel fetal magentoencephalography system was used to record fetal brain activity. Light flashes as visual stimulation were applied to the fetus. The Student's t-test for paired groups was performed. Latency of fetal visual evoked magnetic responses (VER). The IUGR fetuses showed delayed VERs compared with controls (IUGR, 233.1 ms; controls, 184.6 ms; P = 0.032). SGA fetuses had similar evoked response latencies compared with controls (SGA, 216.1 ms; controls, 219.9 ms; P = 0.828). Behavioural states were similarly distributed. Visual evoked responses are delayed in IUGR fetuses, but not in SGA. Fetal behavioural state as an influencing factor of brain response latency was accounted for in the comparison. This reinforces that delayed brain maturation is the result of placental insufficiency. © 2015 Royal College of Obstetricians and Gynaecologists.

  1. Small RNA sequencing-microarray analyses in Parkinson leukocytes reveal deep brain stimulation-induced and splicing changes that classify brain region transcriptomes

    Directory of Open Access Journals (Sweden)

    Lilach eSoreq

    2013-05-01

    Full Text Available MicroRNAs (miRNAs are key post transcriptional regulators of their multiple target genes. However, the detailed profile of miRNA expression in Parkinson's disease, the second most common neurodegenerative disease worldwide and the first motor disorder has not been charted yet. Here, we report comprehensive miRNA profiling by next-generation small-RNA sequencing, combined with targets inspection by splice-junction and exon arrays interrogating leukocyte RNA in Parkinson’s disease patients before and after deep brain stimulation (DBS treatment and of matched healthy control volunteers (HC. RNA-Seq analysis identified 254 miRNAs and 79 passenger strand forms as expressed in blood leukocytes, 16 of which were modified in patients pre treatment as compared to HC. 11 miRNAs were modified following brain stimulation, 5 of which were changed inversely to the disease induced changes. Stimulation cessation further induced changes in 11 miRNAs. Transcript isoform abundance analysis yielded 332 changed isoforms in patients compared to HC, which classified brain transcriptomes of 47 PD and control independent microarrays. Functional enrichment analysis highlighted mitochondrion organization. DBS induced 155 splice changes, enriched in ubiquitin homeostasis. Cellular composition analysis revealed immune cell activity pre and post treatment. Overall, 217 disease and 74 treatment alternative isoforms were predictably targeted by modified miRNAs within both 3’ and 5’ untranslated ends and coding sequence sites. The stimulation-induced network sustained 4 miRNAs and 7 transcripts of the disease network. We believe that the presented dynamic networks provide a novel avenue for identifying disease and treatment-related therapeutic targets. Furthermore, the identification of these networks is a major step forward in the road for understanding the molecular basis for neurological and neurodegenerative diseases and assessment of the impact of brain stimulation

  2. EGFR mutations are associated with favorable intracranial response and progression-free survival following brain irradiation in non-small cell lung cancer patients with brain metastases

    Science.gov (United States)

    2012-01-01

    Background The presence of epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) is associated with increased radiosensitivity in vitro. However, the results from clinical studies regarding the radiosensitivity in NSCLC with mutant EGFR are inconclusive. We retrospectively analyzed our NSCLC patients who had been regularly followed up by imaging studies after irradiation for brain metastases, and investigated the impact of EGFR mutations on radiotherapy (RT). Methods Forty-three patients with brain metastases treated with RT, together with EGFR mutation status, demographics, smoking history, performance status, recursive partitioning analysis (RPA) class, tumor characteristics, and treatment modalities, were included. Radiological images were taken at 1 to 3 months after RT, and 3 to 6 months thereafter. Radiographic response was evaluated by RECIST criteria version 1.1 according to the intracranial images before and after RT. Log-rank test and Cox regression model were used to correlate EGFR mutation status and other clinical features with intracranial radiological progression-free survival (RPFS) and overall survival (OS). Results The median follow-up duration was 15 months. Patients with mutant EGFR had higher response rates to brain RT than those with wild-type EGFR (80% vs. 46%; p = 0.037). Logistic regression analysis showed that EGFR mutation status is the only predictor for treatment response (p = 0.032). The median intracranial RPFS was 18 months (95% CI = 8.33-27.68 months). In Cox regression analysis, mutant EGFR (p = 0.025) and lower RPA class (p = 0.026) were associated with longer intracranial RPFS. EGFR mutation status (p = 0.061) and performance status (p = 0.076) had a trend to predict OS. Conclusions Mutant EGFR in NSCLC patients is an independent prognostic factor for better treatment response and longer intracranial RPFS following RT for brain metastases. PMID:23110940

  3. Biodistribution of ultra small gadolinium-based nanoparticles as theranostic agent: application to brain tumors.

    Science.gov (United States)

    Miladi, Imen; Duc, Géraldine Le; Kryza, David; Berniard, Aurélie; Mowat, Pierre; Roux, Stéphane; Taleb, Jacqueline; Bonazza, Pauline; Perriat, Pascal; Lux, François; Tillement, Olivier; Billotey, Claire; Janier, Marc

    2013-09-01

    Gadolinium-based nanoparticles are novel objects with interesting physical properties, allowing their use for diagnostic and therapeutic applications. Gadolinium-based nanoparticles were imaged following intravenous injection in healthy rats and rats grafted with 9L gliosarcoma tumors using magnetic resonance imaging and scintigraphic imaging. Quantitative biodistribution using gamma-counting of each sampled organ confirmed that these nanoparticles were rapidly cleared essentially by renal excretion. Accumulation of these nanoparticles in 9L gliosarcoma tumors implanted in the rat brain was quantitated. This passive and long-duration accumulation of gadolinium-based nanoparticles in tumor, which is related to disruption of the blood-brain barrier, is in good agreement with the use of these nanoparticles as radiosensitizers for brain tumors.

  4. The Current Role of Whole Brain Radiation Therapy in Non-Small Cell Lung Cancer Patients.

    Science.gov (United States)

    Loganadane, Gokoulakrichenane; Hendriks, Lizza; Le Péchoux, Cécile; Levy, Antonin

    2017-10-01

    The incidence of brain metastases has increased in patients with NSCLC as a result of better systemic disease control and advances in imaging modalities. Whole brain radiotherapy (WBRT) has been the mainstay treatment of multiple symptomatic brain metastases for years. A number of recent publications have questioned its place in the absence of a survival and quality of life benefit and the possible risk for long-term neurotoxicity. Omission or deferral of WBRT and strategies consisting of stereotactic radiosurgery or delivery of systemic therapies alone are being proposed more and more. However, critical analysis of the literature shows that WBRT still has relevant indications in well-selected patients. Within this review, we discuss the place of WBRT in the modern management of patients with NSCLC. Copyright © 2017 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.

  5. Prognostic factors to predict survival in non-small-cell lung cancer with brain metastasis

    Institute of Scientific and Technical Information of China (English)

    Tiantian Li; Xuezhen Ma; Yuan Yao

    2014-01-01

    Objective:The purpose of the study was to assess prognostic factors to predict overal survival (OS) and progres-sion-free survival (PFS) in non-smal-celllung cancer (NSCLC) with brain metastasis (BM). Methods:From November 2011 to March 2013, the clinical data of 31 NSCLC cases with BM treated with multiple modalities including brain radiotherapy alone, systemic chemotherapy, whole brain radiotherapy (WBRT) combined with tyrosine kinase inhibitor (TKIs). The ef icacy and adverse reaction were evaluated after treatment. Results:In terms of intracranial lesions, the objective response rate (ORR) and the disease control rate (DCR) were 22.6%and 90.3%, respectively. As for systemic disease, ORR and DCR were 32.3%and 93.5%, respectively. The median time to progression-free survival (PFS) was 298 days (95%CI:258.624-337.376 days), whereas in the epidermal growth factor receptor (EGFR) mutation patients was 331 days. Patients who received EGFR-TKIs combined with brain radiation had better response rate (RR) than those only brain radiation. Univariate analysis showed that the EGFR-mutations could predictive factors for PFS, and not to other clinical pathological features. The most common toxici-ties were rash and diarrhea, but al were wel-tolerated. Conclusion:EGFR-mutations is the independent prognostic factors af ecting the survival rates of NSCLC patients with BM. Through the clinical observation, icotinib combined with WBRT may be ef ective on brain metastases in NSCLC patients, and toxicities are tolerable, which worth further study.

  6. 具有高对称性的小世界网络模型研究%Research on Small World Network Model with High Symmetry

    Institute of Scientific and Technical Information of China (English)

    张付仁; 刘浩

    2011-01-01

    Based on research of small-world network and Cayley graph, it adopts the algebra and graph theory method of Cayley graph, a model of small-world network with high symmetry is proposed. Some properties of small-world such as clustering coefficient and characteristic path length are analyzed. A routing algorithm is developed. Results of analysis and simulation testify this model provides high local clustering and low network diameter, possesses the property of small-world.%在研究小世界网络和Cayley图的基础上,采用基于Cayley图的代数图论方法,给出一种具有高对称性的小世界网络模型,分析该模型的聚类系数和特征路径长度等小世界性质,给出其路由算法.分析结果表明,该模型聚类性高、网络直径小,具有小世界特性.

  7. Self-organized Criticality and Synchronization in a Pulse-coupled Integrate-and-Fire Neuron Model Based on Small World Networks

    Institute of Scientific and Technical Information of China (English)

    LIN Min; CHEN Tian-Lun

    2005-01-01

    A lattice model for a set of pulse-coupled integrate-and-fire neurons with small world structure is introduced.We find that our model displays the power-law behavior accompanied with the large-scale synchronized activities among the units. And the different connectivity topologies lead to different behaviors in models of integrate-and-fire neurons.

  8. Small Worlds, Lifeworlds, and Information: The Ramifications of the Information Behaviour of Social Groups in Public Policy and the Public Sphere

    Science.gov (United States)

    Burnett, Gary; Jaeger, Paul T.

    2008-01-01

    Introduction: This paper attempts to build bridges between two sets of theoretical concepts related to information behaviour: the macro-level concepts of Jurgen Habermas related to lifeworlds and the micro-level concepts of Elfreda Chatman related to small worlds. Argument: Habermas and Chatman explored similar issues of information behaviour at…

  9. Brain responses to world knowledge violations: a comparison of stimulus- and fixation-triggered event-related potentials and neural oscillations.

    Science.gov (United States)

    Metzner, Paul; von der Malsburg, Titus; Vasishth, Shravan; Rösler, Frank

    2015-05-01

    Recent research has shown that brain potentials time-locked to fixations in natural reading can be similar to brain potentials recorded during rapid serial visual presentation (RSVP). We attempted two replications of Hagoort, Hald, Bastiaansen, and Petersson [Hagoort, P., Hald, L., Bastiaansen, M., & Petersson, K. M. Integration of word meaning and world knowledge in language comprehension. Science, 304, 438-441, 2004] to determine whether this correspondence also holds for oscillatory brain responses. Hagoort et al. reported an N400 effect and synchronization in the theta and gamma range following world knowledge violations. Our first experiment (n = 32) used RSVP and replicated both the N400 effect in the ERPs and the power increase in the theta range in the time-frequency domain. In the second experiment (n = 49), participants read the same materials freely while their eye movements and their EEG were monitored. First fixation durations, gaze durations, and regression rates were increased, and the ERP showed an N400 effect. An analysis of time-frequency representations showed synchronization in the delta range (1-3 Hz) and desynchronization in the upper alpha range (11-13 Hz) but no theta or gamma effects. The results suggest that oscillatory EEG changes elicited by world knowledge violations are different in natural reading and RSVP. This may reflect differences in how representations are constructed and retrieved from memory in the two presentation modes.

  10. Dosimetry analysis of small radiation fields in stereotactic radiosurgery of the brain

    Science.gov (United States)

    Al-Najjar, Waleed Hassan

    Accurate dosimetric data of narrow circular photon beams are needed for stereotactic radiosurgery of brain tumors. However, the measurement of dosimetric data of narrow circular beams is beset with several constraints. Usually, 6 MV photon beams produced by isocentric linear accelerators are mostly used for routine radiosurgery although other photon energies are available. Systematic dosimetric studies were performed on 12.5, 20, 30 and 40 mm diameter collimators using different measuring techniques in order to examine the possible accuracies associated in the measured dosimetric data of narrow circular photon beams. In addition, the relative suitabilities of 4, 6 and 10 MV photon beams for stereotactic radiosurgery were assessed. The lack of electronic equilibrium and steep dose gradient effects were found to be minimal for a 4 MV photon beam compared to the 6 and 10 MV photon beams. The measured output factors with a small volume (0.02 cc) ionization chamber were found to agree with film and MOSFET (Metal Oxide Semiconductor Field Effect Transistor) detector measurements for 4 MV photon beam even for smaller field sizes. The measured beam profiles were also found to be in better agreement with the expected shapes for the 4 MV beam than for 6 and 10 MV beams. The 80% isodose volumes for a typical 20.0 mm diameter field for 1 to 10 non-coplanar converging arcs showed that the volumes for the 4 MV beam are slightly larger than the corresponding volumes for the 6 and 10 MV photon beams for any given isodose level. The dose fall- off distances from the 80% to 50% isodoses are also, in general, found to be smaller for the 4 MV beam. Therefore, for radiosurgery, the dose calculations for the 4 MV beam have less uncertainty than the dose calculations for the 6 and 10 MV beams. The output factors can be measured with an ionization chamber for the 4 MV photon beam over the range 12.5 to 40.0 mm diameter field size, whereas for the 6 MV beam they can only be measured for

  11. New neurons in aging brains: molecular control by small non-coding RNAs.

    NARCIS (Netherlands)

    M. Schouten; M.R. Buijink; P.J. Lucassen; C.P. Fitzsimons

    2012-01-01

    Adult neurogenesis generates functional neurons from neural stem cells present in specific brain regions. It is largely confined to two main regions: the subventricular zone of the lateral ventricle, and the subgranular zone of the dentate gyrus (DG), in the hippocampus. With age, the function of th

  12. Interstitial laser thermotherapy: developments in the treatment of small deep-seated brain tumors.

    Science.gov (United States)

    Menovsky, T; Beek, J F; Roux, F X; Bown, S G

    1996-12-01

    New technical advances have made feasible the utilization of laser to destroy deep-seated brain tumors under real-time monitoring. Experience with interstitial laser thermotherapy (ILTT) in animal and clinical studies has been obtained. These studies are summarized and the future potential of ILTT in neurosurgery is discussed.

  13. New neurons in aging brains: molecular control by small non-coding RNAs.

    NARCIS (Netherlands)

    Schouten, M.; Buijink, M.R.; Lucassen, P.J.; Fitzsimons, C.P.

    2012-01-01

    Adult neurogenesis generates functional neurons from neural stem cells present in specific brain regions. It is largely confined to two main regions: the subventricular zone of the lateral ventricle, and the subgranular zone of the dentate gyrus (DG), in the hippocampus. With age, the function of

  14. A small frog that makes a big difference: brain wave testing of TV advertisements.

    Science.gov (United States)

    Ohme, Rafal; Matukin, Michal

    2012-01-01

    It is important for the marketing industry to better understand the role of the unconscious and emotions in advertising communication and shopping behavior. Yet, traditional consumer research is not enough for such a purpose. Conventional paper-and-pencil or verbal declarations favor conscious pragmatism and functionality as the principles underlying consumer decisions and motives. These approaches should be combined with an emerging discipline (consumer neuroscience or neuromarketing) to examine the brain and its functioning in the context of consumer choices. It has been widely acknowledged that patterns of brain activity are closely related to consumers cognition and behavior. Thus, the analysis of consumers neurophysiology may increase the understanding of how consumers process incoming information and how they use their memory and react emotionally (See "Three Types of Brain Wave Research on TV Advertisements"): Moreover, as the majority of consumer mental processes occur below the level of conscious awareness, observations of the brain reactions enable researchers to reach the very core (which is consciously inaccessible) foundations of consumer decisions, emotions, motivations, and preferences.

  15. High-density speckle contrast optical tomography (SCOT) for three dimensional tomographic imaging of the small animal brain.

    Science.gov (United States)

    Dragojević, Tanja; Varma, Hari M; Hollmann, Joseph L; Valdes, Claudia P; Culver, Joseph P; Justicia, Carles; Durduran, Turgut

    2017-06-01

    High-density speckle contrast optical tomography (SCOT) utilizing tens of thousands of source-detector pairs, was developed for in vivo imaging of blood flow in small animals. The reduction in cerebral blood flow (CBF) due to local ischemic stroke in a mouse brain was transcanially imaged and reconstructed in three dimensions. The reconstructed volume was then compared with corresponding magnetic resonance images demonstrating that the volume of reduced CBF agrees with the infarct zone at twenty-four hours. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  16. Is Sex an Indicator of Prognosis After Mild Traumatic Brain Injury: A Systematic Analysis of the Findings of the World Health Organization Collaborating Centre Task Force on Mild Traumatic Brain Injury and the International Collaboration on Mild Traumatic Brain Injury Prognosis.

    Science.gov (United States)

    Cancelliere, Carol; Donovan, James; Cassidy, J David

    2016-02-01

    To determine sex differences in the recovery and prognosis after mild traumatic brain injury (MTBI) in adults and children. We analyzed all scientifically admissible primary studies in the World Health Organization (WHO) (n=120) and International Collaboration on Mild Traumatic Brain Injury Prognosis (ICoMP) (n=101) systematic reviews regarding prognosis of MTBI for sex-stratified findings. They searched MEDLINE and other databases from 1980 through 2000 (WHO) and 2001 through 2012 (ICoMP) for published, peer-reviewed reports in English and other languages. We selected controlled trials and cohort and case-control studies that assessed the effect of sex on outcomes after MTBI. Data from the eligible studies from both systematic reviews combined (n=14, 7%) were extracted into evidence tables. Prognostic information relating to sex was prioritized according to design as exploratory or confirmatory, and a best-evidence synthesis was conducted. After MTBI, females may have a higher risk of epilepsy (children, young adults) and suicide, and use more health care services; males may be at higher risk for schizophrenia. Most studies did not find a sex difference for postconcussion symptoms in children and adults. No sex difference was found for risk of dementia and primary brain tumor, return to work, or posttraumatic stress syndrome. Sex is not a well-studied prognostic indicator for recovery after MTBI, but small sex differences were found for some outcomes. More well-designed studies are needed that report outcomes according to sex and control for potential confounders. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  17. Whole brain radiotherapy plus concurrent chemotherapy in non-small cell lung cancer patients with brain metastases: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Hong Qin

    Full Text Available The aim of the present meta-analysis is to evaluate the response rate, median survival time (MST and toxicity in patients with brain metastases (BM originating from non-small cell lung cancer (NSCLC and who were treated using either whole brain radiotherapy (WBRT plus concurrent chemotherapy or WBRT alone.PubMed, EMBASE, Web of Science, The Cochrane Library, clinical trials and current controlled trials were searched to identify any relevant publications. After screening the literature and undertaking quality assessment and data extraction, the meta-analysis was performed using Stata11.0 software.In total, six randomized controlled trials (RCT involving 910 participants were included in the meta-analysis. The results of the analysis indicate that WBRT plus concurrent chemotherapy was more effective at improving response rate (RR = 2.06, 95% CI [1.13, 3.77]; P = 0.019 than WBRT alone. However, WBRT plus concurrent chemotherapy did not improve median survival time (MST (HR = 1.09, 95%CI [0.94, 1.26]; P = 0.233 or time of neurological progression (CNS-TTP (HR = 0.93, 95%CI [0.75, 1.16]; P = 0.543, and increased adverse events (Grade≥3 (RR = 2.59, 95% CI [1.88, 3.58]; P = 0.000. There were no significant differences in Grade 3-5 neurological or hematological toxicity between two patient groups (RR = 1.08, 95%CI [0.23, 5.1]; P = 0.92.The combination of chemotherapy plus WBRT in patients with BM originating from NSCLC may increase treatment response rates of brain metastases with limited toxicity. Although the therapy schedule did not prolong MST or CNS-TTP, further assessment is warranted.

  18. Timing of Whole Brain Radiotherapy on Survival of Patients with EGFR-mutated 
Non-small Cell Lung Cancer and Brain Metastases

    Directory of Open Access Journals (Sweden)

    Guimei LIU

    2016-08-01

    Full Text Available Background and objective There is no high-level evidence for the time of whole brain radiotherapy (WBRT for patients with epidermal growth factor receptor (EGFR-mutated non-small cell lung cancer (NSCLC and brain metastases. The aim of this study is to assess the appropriate timing of WBRT for patients with EGFR-mutated NSCLC and brain metastases (BM. Methods There were 78 patients diagnosed with EGFR-mutated NSCLC and BM in Beijing Chest Hospital between August 2009 and May 2015. 48 untreated patients who received both WBRT and EGFR-tyrosine kinase inhibitors (TKIs therapy. Prognostic factors of intracranial progression-free survival (PFS and overall survival (OS were identified by Cox proportional hazards modeling. Results Intracranial objective response rate was 81.3% and disease control rate was 93.8%. Median intracranial PFS was 10 months. Median OS was 18 months. Multivariate analysis of intracranial PFS revealed that Eastern Cooperative Oncology Group (ECOG performance status (PS 0-1 (HR=30.436, 95%CI: 4.721-196.211, P<0.001 and early WBRT (HR=3.663, 95%CI: 1.657-8.098, P=0.001 had a better intracranial PFS. Multivariate analysis of OS revealed that PS 0-1 (HR=57.607, 95%CI: 6.135-540.953, P<0.001, early WBRT (HR=2.757, 95%CI: 1.140-6.669, P=0.024, and stereotactic radiosurgery (HR=5.964, 95%CI: 1.895-18.767, P=0.002 were independent prognostic factors of OS. Conclusion Early WBRT combined with EGFR-TKIs can improve outcomes of patients with EGFR-mutated NSCLC and BM, but it needs to be confirmed by large-sample-size and multicenter prospective clinical trials.

  19. Cognition in an ever-changing world: climatic variability is associated with brain size in Neotropical parrots.

    Science.gov (United States)

    Schuck-Paim, Cynthia; Alonso, Wladimir J; Ottoni, Eduardo B

    2008-01-01

    Research on the conditions favoring the evolution of complex cognition and its underlying neural structures has increasingly stressed the role of environmental variability. These studies suggest that the ability to learn, behave flexibly and innovate would be favored under unpredictable variations in the availability of resources, as it would enable organisms to adjust to novel conditions. Despite the growing number of studies based on the idea that larger-brained organisms would be better prepared to cope with environmental challenges, direct testing of the association between brain size and environmental variability per se remains scant. Here we focus on Neotropical parrots as our model group and test the hypothesis that if relatively larger brains were favored in climatically variable environments, larger-brained species should currently tolerate a higher degree of environmental uncertainty. Although we show that there are also other factors underlying the dynamics of brain size variation in this group, our results support the hypothesis that proportionally larger-brained species are more tolerant to climatic variability, both on a temporal and spatial scale. Additionally, they suggest that the differences in relative brain size among Neotropical parrots represent multiple, recent events in the evolutionary history of the group, and are particularly tied to an increased dependence on more open and climatically unstable habitats. As this is the first study to present evidence of the link between brain size and climatic variability in birds, our findings provide a step towards understanding the potential benefits underlying variation in brain size and the maintenance of highly enlarged brains in this and other groups.

  20. Extrapulmonary small cell sarcinoma: involvement of the brain without evidence of extracranial malignancy by serial PET/CT scans

    Directory of Open Access Journals (Sweden)

    Havlioglu Necat

    2008-09-01

    Full Text Available Abstract Background Extrapulmonary small cell carcinoma (EPSCC involving the brain is a rare manifestation of an uncommon tumor type. Case presentation We report a 59 year-old Caucasian female diagnosed with an EPSCC involving the left parietal lobe without detectable extracranial primary tumor followed by serial positron emission tomography/computed tomography (PET/CT imaging. Histopathological examination at both initial presentation and recurrence revealed small cell carcinoma. Serial PET/CT scans of the entire body failed to reveal any extracranial [18F]2-fluoro-2-deoxy-D-glucose (FDG avid lesions at either diagnosis or follow-up. Conclusion Chemotherapy may show a transient response in the treatment of EPSCC. Further studies are needed to help identify optimal treatment strategies. Combination PET/CT technology may be a useful tool to monitor EPSCC and assess for an occult primary malignancy.

  1. Anatomical standardization of small animal brain FDG-PET images using synthetic functional template: experimental comparison with anatomical template.

    Science.gov (United States)

    Coello, Christopher; Hjornevik, Trine; Courivaud, Frédéric; Willoch, Frode

    2011-07-15

    Anatomical standardization (also called spatial normalization) of positron emission tomography (PET) small animal brain images is required to make statistical comparisons across individuals. Frequently, PET images are co-registered to an individual MR or CT image of the same subject in order to transform the functional images to an anatomical space. In the present work, we evaluate the normalization of synthetic PET (synPET) images to a synthetic PET template. To provide absolute error in terms of pixel misregistration, we created a synthetic PET image from the individual MR image through segmentation of the brain into gray and white matter which produced functional and anatomical images in the same space. When comparing spatial normalization of synPET images to a synPET template with the gold standard (MR images to an MR template), a mean translation error of 0.24mm (±0.20) and a maximal mean rotational error of 0.85° (±0.91) were found. Significant decrease in misregistration error was measured when achieving spatial normalization of functional images to a functional template instead of an anatomical template. This accuracy strengthens the use of standardization methods where individual PET images are registered to a customized PET template in order to statistically assess physiological changes in rat brains.

  2. High probability and frequency of EGFR mutations in non-small cell lung cancer with brain metastases.

    Science.gov (United States)

    Ge, Mengxi; Zhuang, Yingjie; Zhou, Xinli; Huang, Ruofan; Liang, Xiaohua; Zhan, Qiong

    2017-08-05

    Lung cancer is the leading cause of cancer death in men and women worldwide. Brain metastasis (BMs) of non-small cell lung cancer (NSCLC) is the most important cause of death. This study aimed to explore the association of epidermal growth factor receptor (EGFR) mutations and BMs in NSCLC. We analyzed 50 NSCLC patients with BMs and 50 match-paired NSCLC patients with no brain metastases (NBMs). The EGFR mutation status of primary lesions was detected using the amplification refractory mutation system polymerase chain reaction. The BMs patients had a higher frequency of EGFR mutations than the NBMs patients (52.0 vs. 22.0% respectively, P < 0.001), in both adenocarcinoma (60.5 vs. 30.6%, P = 0.003) and squamous carcinoma (37.5 vs. 0%, P = 0.04). The incidence of BMs in patients with EGFR mutations was higher than in patients with wild-type EGFR (70.3 vs. 38.1%, P = 002). NSCLC patients with BMs had a higher incidence of EGFR mutations and those with mutant EGFR had a higher frequency of BMs. EGFR mutations may promote brain metastasis growth of NSCLC.

  3. Phenotypic Screening of Small-Molecule Inhibitors: Implications for Therapeutic Discovery and Drug Target Development in Traumatic Brain Injury.

    Science.gov (United States)

    Al-Ali, Hassan; Lemmon, Vance P; Bixby, John L

    2016-01-01

    The inability of central nervous system (CNS) neurons to regenerate damaged axons and dendrites following traumatic brain injury (TBI) creates a substantial obstacle for functional recovery. Apoptotic cell death, deposition of scar tissue, and growth-repressive molecules produced by glia further complicate the problem and make it challenging for re-growing axons to extend across injury sites. To date, there are no approved drugs for the treatment of TBI, accentuating the need for relevant leads. Cell-based and organotypic bioassays can better mimic outcomes within the native CNS microenvironment than target-based screening methods and thus should speed the discovery of therapeutic agents that induce axon or dendrite regeneration. Additionally, when used to screen focused chemical libraries such as small-molecule protein kinase inhibitors, these assays can help elucidate molecular mechanisms involved in neurite outgrowth and regeneration as well as identify novel drug targets. Here, we describe a phenotypic cellular (high content) screening assay that utilizes brain-derived primary neurons for screening small-molecule chemical libraries.

  4. The involvement of nitric oxide in the hemodynamic and metabolic activities of the brain and small intestine

    Science.gov (United States)

    Tolmasov, M.; Barbiro-Michaely, E.; Mayevsky, A.

    2009-02-01

    Nitric oxide is a mediator in many physiological processes including vasodilatation of blood vessels, neurotransmission and prevention of platelet aggregation. It has also a role in the pathophysiology of sepsis, hemorrhagic shock, various traumatic events and critical conditions involved with circulatory abnormalities. The last one is accompanied by blood flow redistribution and is considered to be the putative cause of altered oxygen metabolism in various pathophysiological conditions. The present study tested the involvement of NO in the brain as a vital organ versus the small intestine, a less vital organ using the non-specific nitric oxide synthase inhibitor L-NAME and exogenous NO donor - nitrite. The parameters that were simultaneously monitored in both organs included mean arterial blood pressure (MAP), tissue blood flow (TBF), using laser Doppler flowmetery and NADH fluorescence using the fluorometric technique. Three groups were tested. Group 1 - L-NAME +nitrite, group 2 - control L-NAME and group 3 - control nitrite. Following LNAME, MAP significantly increased and remained elevated through the entire experiment. TBF decreased in both organs with full recovery in the brain and no recovery in the intestine, whereas NADH showed no significant changes. Nitrite alone had no significant effect on the parameters in any of the organs. In group 1 the infusion of nitrite decreased the level of elevated MAP earlier induced by L-NAME. Nitrite also recovered the reduced TBF in the brain whereas it had no beneficial effect on intestinal blood flow indicating for its regulatory role in the brain but not in the intestine.

  5. Use of Stereotactic Radiosurgery for Brain Metastases From Non-Small Cell Lung Cancer in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Halasz, Lia M., E-mail: lhalasz@uw.edu [Department of Radiation Oncology, University of Washington, Seattle, Washington (United States); Harvard Radiation Oncology Program, Harvard Medical School, Boston, Massachusetts (United States); Weeks, Jane C.; Neville, Bridget A.; Taback, Nathan [Division of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts (United States); Punglia, Rinaa S. [Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts (United States)

    2013-02-01

    Purpose: The indications for treatment of brain metastases from non-small cell lung cancer (NSCLC) with stereotactic radiosurgery (SRS) remain controversial. We studied patterns, predictors, and cost of SRS use in elderly patients with NSCLC. Methods and Materials: Using the Surveillance, Epidemiology, and End Results-Medicare (SEER-Medicare) database, we identified patients with NSCLC who were diagnosed with brain metastases between 2000 and 2007. Our cohort included patients treated with radiation therapy and not surgical resection as initial treatment for brain metastases. Results: We identified 7684 patients treated with radiation therapy within 2 months after brain metastases diagnosis, of whom 469 (6.1%) cases had billing codes for SRS. Annual SRS use increased from 3.0% in 2000 to 8.2% in 2005 and varied from 3.4% to 12.5% by specific SEER registry site. After controlling for clinical and sociodemographic characteristics, we found SRS use was significantly associated with increasing year of diagnosis, specific SEER registry, higher socioeconomic status, admission to a teaching hospital, no history of participation in low-income state buy-in programs (a proxy for Medicaid eligibility), no extracranial metastases, and longer intervals from NSCLC diagnosis. The average cost per patient associated with radiation therapy was 2.19 times greater for those who received SRS than for those who did not. Conclusions: The use of SRS in patients with metastatic NSCLC increased almost 3-fold from 2000 to 2005. In addition, we found significant variations in SRS use across SEER registries and socioeconomic quartiles. National practice patterns in this study suggested both a lack of consensus and an overall limited use of the approach among elderly patients before 2008.

  6. Tight junction modulation of the blood brain barrier: CNS delivery of small molecules.

    Science.gov (United States)

    Greene, Chris; Campbell, Matthew

    2016-01-01

    The blood brain barrier (BBB) represents a major obstacle for targeted drug delivery to the brain for the treatment of central nervous system (CNS) disorders. Significant advances in barrier research over the past decade has led to the discovery of an increasing number of structural and regulatory proteins in tight junctions (TJ) and adherens junctions (AJ). These discoveries are providing the framework for the development of novel TJ modulators which can act specifically and temporarily to alter BBB function and regulate paracellular uptake of molecules. TJ modulators that have shown therapeutic potential in preclinical models include claudin-5 and occludin siRNAs, peptides derived from zonula occludens toxin as well as synthetic peptides targeting the extracellular loops of TJs. Adding to the array of modulating agents are novel mechanisms of BBB regulation such as focused ultrasound (FUS). This review will give a succinct overview of BBB biology and TJ modulation in general. Novel insights into BBB regulation in health and disease will also be summarized.

  7. Empirical Analysis on Evolution and Small World Effect of Chinese Enterprise-Enterprise Patent Cooperation Network: From the Perspective of Open Innovation

    Directory of Open Access Journals (Sweden)

    Wei Li

    2013-10-01

    Full Text Available The patent cooperation network which enterprises join is a very important network platform for enterprises’ open innovation. However, very limited work has been done to empirically investigate the dynamic change process of the network in China. To address this issue, this paper analyzes dynamic change process of cooperation network of enterprises and the small-world effect of the biggest subgroup according to the data of 36731 items of cooperative patents between enterprises from 1985 to 2010 published by the State Intellectual Property Office of China. A conclusion can be drawn from the analysis results that the biggest subgroup has the characteristics of small-world effect, but the overall network structure also has some defects, which limit the development of open innovation. For the first time, suggestions on open innovation strategies are put forward to provide theoretical reference for both the government and enterprises.

  8. Citizen Science: The Small World Initiative Improved Lecture Grades and California Critical Thinking Skills Test Scores of Nonscience Major Students at Florida Atlantic University.

    Science.gov (United States)

    Caruso, Joseph P; Israel, Natalie; Rowland, Kimberly; Lovelace, Matthew J; Saunders, Mary Jane

    2016-03-01

    Course-based undergraduate research is known to improve science, technology, engineering, and mathematics student achievement. We tested "The Small World Initiative, a Citizen-Science Project to Crowdsource Novel Antibiotic Discovery" to see if it also improved student performance and the critical thinking of non-science majors in Introductory Biology at Florida Atlantic University (a large, public, minority-dominant institution) in academic year 2014-15. California Critical Thinking Skills Test pre- and posttests were offered to both Small World Initiative (SWI) and control lab students for formative amounts of extra credit. SWI lab students earned significantly higher lecture grades than control lab students, had significantly fewer lecture grades of D+ or lower, and had significantly higher critical thinking posttest total scores than control students. Lastly, more SWI students were engaged while taking critical thinking tests. These results support the hypothesis that utilizing independent course-based undergraduate science research improves student achievement even in nonscience students.

  9. Citizen Science: The Small World Initiative Improved Lecture Grades and California Critical Thinking Skills Test Scores of Nonscience Major Students at Florida Atlantic University

    Directory of Open Access Journals (Sweden)

    Joseph Paul Caruso

    2015-12-01

    Full Text Available Course-based undergraduate research is known to improve science, technology, engineering, and mathematics student achievement. We tested “The Small World Initiative, a Citizen-Science Project to Crowdsource Novel Antibiotic Discovery” to see if it also improved student performance and the critical thinking of nonscience majors in Introductory Biology at Florida Atlantic University (a large, public, minority-dominant institution in academic year 2014–15. California Critical Thinking Skills Test pre- and posttests were offered to both Small World Initiative (SWI and control lab students for formative amounts of extra credit. SWI lab students earned significantly higher lecture grades than control lab students, had significantly fewer lecture grades of D+ or lower, and had significantly higher critical thinking posttest total scores than control students. Lastly, more SWI students were engaged while taking critical thinking tests. These results support the hypothesis that utilizing independent course-based undergraduate science research improves student achievement even in nonscience students.

  10. Fractality of sensations and the brain health: the theory linking neurodegenerative disorder with distortion of spatial and temporal scale-invariance and fractal complexity of the visible world

    Directory of Open Access Journals (Sweden)

    Marina Vladimirovna Zueva

    2015-07-01

    Full Text Available The theory that ties normal functioning and pathology of the brain and visual system with the spatial-temporal structure of the visual and other sensory stimuli is described for the first time in the present study. The deficit of fractal complexity of environmental influences can lead to the distortion of fractal complexity in the visual pathways of the brain and abnormalities of development or aging. The use of fractal light stimuli and fractal stimuli of other modalities can help to restore the functions of the brain, particularly in the elderly and in patients with neurodegenerative disorders or amblyopia. Nonlinear dynamics of these physiological processes have a strong base of evidence, which is seen in the impaired fractal regulation of rhythmic activity in aged and diseased brains. From birth to old age, we live in a nonlinear world, in which objects and processes with the properties of fractality and non-linearity surround us. Against this background, the evolution of man took place and all periods of life unfolded. Works of art created by man may also have fractal properties. The positive influence of music on cognitive functions is well-known. Insufficiency of sensory experience is believed to play a crucial role in the pathogenesis of amblyopia and age-dependent diseases. The brain is very plastic in its early development, and the plasticity decreases throughout life. However, several studies showed the possibility to reactivate the adult's neuroplasticity in a variety of ways. We propose that a non-linear structure of sensory information on many spatial and temporal scales is crucial to the brain health and fractal regulation of physiological rhythms. Theoretical substantiation of the author's theory is presented. Possible applications and the future research that can experimentally confirm or refute the theoretical concept are considered.

  11. Sir Hugh Cairns and World War II British advances in head injury management, diffuse brain injury, and concussion: an Oxford tale.

    Science.gov (United States)

    Stone, James L; Patel, Vimal; Bailes, Julian E

    2016-11-01

    The authors trace the Oxford, England, roots of World War II (WWII)-related advances in head injury management, the biomechanics of concussion and brain injury, and postwar delineation of pathological findings in severe concussion and diffuse brain injury in man. The prominent figure in these developments was the charismatic and innovative Harvey Cushing-trained neurosurgeon Sir Hugh Cairns. Cairns, who was to closely emulate Cushing's surgical and scholarly approach, is credited with saving thousands of lives during WWII by introducing and implementing innovative programs such as helmets for motorcyclists, mobile neurosurgical units near battle zones, and the military usage of penicillin. In addition, he inspired and taught a generation of neurosurgeons, neurologists, and neurological nurses in the care of brain and spinal cord injuries at Oxford's Military Hospital for Head Injuries. During this time Cairns also trained the first full-time female neurosurgeon. Pivotal in supporting animal research demonstrating the critical role of acceleration in the causation of concussion, Cairns recruited the physicist Hylas Holbourn, whose research implicated rotary acceleration and shear strains as particularly damaging. Cairns' work in military medicine and head injury remain highly influential in efforts to mitigate and manage brain injury.

  12. Hemorrhage of brain metastasis from non-small cell lung cancer post gefitinib therapy: two case reports and review of the literature

    Directory of Open Access Journals (Sweden)

    Liao Xin-Biao

    2010-02-01

    Full Text Available Abstract Background Gefitinib is one of the small molecule inhibitors of epidermal growth factor receptor tyrosine kinase (EGFR TKIs. Clinical trials have demonstrated it is effective for treatment of a subset of patients with advanced non-small cell lung cancer (NSCLC. Gefitinib has been generally considered to be a relatively safe agent. Besides a small proportion of fatal interstitial pneumonia, the common adverse drug reactions of gefitinib include diarrhea and skin rash, which are generally mild and reversible. Herein, we report the first two cases of brain metastasis hemorrhage that might be involved with the use of gefitinib. Case presentation Two patients with brain metastasis from NSCLC developed brain hemorrhage after gefitinib therapy. The hemorrhage in one case occurred one month after gefitinib combined with whole brain radiation therapy (WBRT, and in the another case hemorrhage developed slowly within brain metastases eight months post gefitinib monotherapy for diffuse pulmonary metastasis from a lung cancer undergone surgical removal previously. Conclusion We speculate brain hemorrhage could be one of the adverse drug reactions of gefitinib treatment for NSCLC and suggest clinicians be aware of this possible rare entity. More data are needed to confirm our findings, especially when gefitinib is used in the settings of brain metastases from NSCLC or other origins.

  13. It's my hair which is covered...but ahhh my brain is uncovered : Muslim Kuwaiti women in a changing world.

    OpenAIRE

    Saleh Almutawa, Ghinaa

    2016-01-01

    Abstract Kuwait has changed dramatically over the last 50 years and simultaneously the world has changed in terms of economic and financial factors, globalization, technology, and religion. These changes have implications for the lives of women in terms of a range of factors such as clothing, relationships, sexuality, childhood, and parenting. This thesis aimed to explore how women make sense of themselves in the context of this changing world taking three different perspectives. I...

  14. Combining Whole-Brain Radiotherapy with Gefitinib/Erlotinib for Brain Metastases from Non-Small-Cell Lung Cancer: A Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Mao-hua Zheng

    2016-01-01

    Full Text Available Background. To comprehensively assess the efficacy and safety of whole-brain radiotherapy (WBRT combined with gefitinib/erlotinib for treatment of brain metastases (BM from non-small-cell lung cancer (NSCLC. Methods. Databases including PubMed, EMBASE.com, Web of Science, and Cochrane Library were searched from inception to April 12, 2015. Studies on randomized controlled trials (RCTs and case-control trials comparing WBRT combined with gefitinib/erlotinib versus WBRT alone for BM from NSCLC were included. Literature selection, data extraction, and quality assessment were performed independently by two trained reviewers. RevMan 5.3 software was used to analyze data. Results. A total of 7 trials involving 622 patients were included. Compared with WBRT alone or WBRT plus chemotherapy, WBRT plus gefitinib/erlotinib could significantly improve response rate (OR = 2.16, 95% CI: 1.35–3.47; P=0.001, remission rate of central nervous system (OR = 6.06, 95% CI: 2.57–14.29; P<0.0001, disease control rate (OR = 3.34, 95% CI: 1.84–6.07; P<0.0001, overall survival (HR = 0.72, 95% CI: 0.58–0.89; P=0.002, and 1-year survival rate (OR = 2.43, 95% CI: 1.51–3.91; P=0.0002. In adverse events (III-IV, statistically significant differences were not found, except for rash (OR = 7.96, 95% CI: 2.02–31.34; P=0.003 and myelosuppression (OR = 0.19, 95% CI: 0.07–0.51; P=0.0010. Conclusions. WBRT plus gefitinib/erlotinib was superior to WBRT alone and well tolerated in patients with BM from NSCLC.

  15. Combining Small-Volume Metabolomic and Transcriptomic Approaches for Assessing Brain Chemistry

    OpenAIRE

    Knolhoff, Ann M.; Nautiyal, Katherine M.; Nemes, Peter; Kalachikov, Sergey; Morozova, Irina; Silver, Rae; Jonathan V. Sweedler

    2013-01-01

    The integration of disparate data types provides a more complete picture of complex biological systems. Here we combine small-volume metabolomic and transcriptomic platforms to determine subtle chemical changes and to link metabolites and genes to biochemical pathways. Capillary electrophoresis–mass spectrometry (CE–MS) and whole-genome gene expression arrays, aided by integrative pathway analysis, were utilized to survey metabolomic/transcriptomic hippocampal neurochemistry. We measured chan...

  16. 极小Cayley图的确定性小世界网络模型%Deterministic small-world network model based on minimal Cayley graph

    Institute of Scientific and Technical Information of China (English)

    刘艳霞; 奚建清; 张芩

    2014-01-01

    小世界网络的确定性模型研究是复杂网络建模领域的重要分支,通过分析Cayley图的极小性与小世界特性的关联,提出一种基于极小Cayley图构造小世界网络的确定性模型。模型通过选择满足条件的极小Cayley图,恰当地扩展其生成集,构造出一类对称性强且结构规则的小世界网络。结果表明,和现有模型不同,该模型可根据需求构造常数度或非常数度网络,且生成网络不仅具有较高的聚集系数和低的网络直径,而且是节点对称的,在通信网络、结构化P2P 覆盖网络等实际领域的拓扑结构设计中具有重要应用。%The research on deterministic small-world network model is an important branch of complex network modeling. This paper analyzes the small-world property of the minimal Cayley graph and proposes a deterministic small-world network model based on minimal Cayley graph. The model constructs a class of small-world networks with high symmetry by selecting a minimal Cayley graph, and appropriately expands its generating set. Compared with the existing models, this model can be used flexibly to get small-world networks with const degree or variable degree, which is adaptable for the disign and analysis of the real networks such as communication network and P2P overlay network.

  17. Establishing a process of irradiating small animal brain using a CyberKnife and a microCT scanner

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Haksoo; Welford, Scott [Department of Radiation Oncology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106 (United States); Fabien, Jeffrey; Zheng, Yiran; Yuan, Jake; Brindle, James; Yao, Min; Lo, Simon; Wessels, Barry; Machtay, Mitchell; Sohn, Jason W., E-mail: jason.sohn@case.edu [Department of Radiation Oncology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106 and University Hospitals of Cleveland, 11100 Euclid Avenue, Cleveland, Ohio 44106 (United States); Sloan, Andrew [Department of Neurosurgery, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106 (United States)

    2014-02-15

    Purpose: Establish and validate a process of accurately irradiating small animals using the CyberKnife G4 System (version 8.5) with treatment plans designed to irradiate a hemisphere of a mouse brain based on microCT scanner images. Methods: These experiments consisted of four parts: (1) building a mouse phantom for intensity modulated radiotherapy (IMRT) quality assurance (QA), (2) proving usability of a microCT for treatment planning, (3) fabricating a small animal positioning system for use with the CyberKnife's image guided radiotherapy (IGRT) system, and (4)in vivo verification of targeting accuracy. A set of solid water mouse phantoms was designed and fabricated, with radiochromic films (RCF) positioned in selected planes to measure delivered doses. After down-sampling for treatment planning compatibility, a CT image set of a phantom was imported into the CyberKnife treatment planning system—MultiPlan (ver. 3.5.2). A 0.5 cm diameter sphere was contoured within the phantom to represent a hemispherical section of a mouse brain. A nude mouse was scanned in an alpha cradle using a microCT scanner (cone-beam, 157 × 149 pixels slices, 0.2 mm longitudinal slice thickness). Based on the results of our positional accuracy study, a planning treatment volume (PTV) was created. A stereotactic body mold of the mouse was “printed” using a 3D printer laying UV curable acrylic plastic. Printer instructions were based on exported contours of the mouse's skin. Positional reproducibility in the mold was checked by measuring ten CT scans. To verify accurate dose delivery in vivo, six mice were irradiated in the mold with a 4 mm target contour and a 2 mm PTV margin to 3 Gy and sacrificed within 20 min to avoid DNA repair. The brain was sliced and stained for analysis. Results: For the IMRT QA using a set of phantoms, the planned dose (6 Gy to the calculation point) was compared to the delivered dose measured via film and analyzed using Gamma analysis (3% and 3 mm

  18. Establishing a process of irradiating small animal brain using a CyberKnife and a microCT scanner.

    Science.gov (United States)

    Kim, Haksoo; Fabien, Jeffrey; Zheng, Yiran; Yuan, Jake; Brindle, James; Sloan, Andrew; Yao, Min; Lo, Simon; Wessels, Barry; Machtay, Mitchell; Welford, Scott; Sohn, Jason W

    2014-02-01

    Establish and validate a process of accurately irradiating small animals using the CyberKnife G4 System (version 8.5) with treatment plans designed to irradiate a hemisphere of a mouse brain based on microCT scanner images. These experiments consisted of four parts: (1) building a mouse phantom for intensity modulated radiotherapy (IMRT) quality assurance (QA), (2) proving usability of a microCT for treatment planning, (3) fabricating a small animal positioning system for use with the CyberKnife's image guided radiotherapy (IGRT) system, and (4)in vivo verification of targeting accuracy. A set of solid water mouse phantoms was designed and fabricated, with radiochromic films (RCF) positioned in selected planes to measure delivered doses. After down-sampling for treatment planning compatibility, a CT image set of a phantom was imported into the CyberKnife treatment planning system--MultiPlan (ver. 3.5.2). A 0.5 cm diameter sphere was contoured within the phantom to represent a hemispherical section of a mouse brain. A nude mouse was scanned in an alpha cradle using a microCT scanner (cone-beam, 157 × 149 pixels slices, 0.2 mm longitudinal slice thickness). Based on the results of our positional accuracy study, a planning treatment volume (PTV) was created. A stereotactic body mold of the mouse was "printed" using a 3D printer laying UV curable acrylic plastic. Printer instructions were based on exported contours of the mouse's skin. Positional reproducibility in the mold was checked by measuring ten CT scans. To verify accurate dose delivery in vivo, six mice were irradiated in the mold with a 4 mm target contour and a 2 mm PTV margin to 3 Gy and sacrificed within 20 min to avoid DNA repair. The brain was sliced and stained for analysis. For the IMRT QA using a set of phantoms, the planned dose (6 Gy to the calculation point) was compared to the delivered dose measured via film and analyzed using Gamma analysis (3% and 3 mm). A passing rate of 99% was measured in

  19. Establishing a process of irradiating small animal brain using a CyberKnife and a microCT scanner

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Haksoo; Welford, Scott [Department of Radiation Oncology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106 (United States); Fabien, Jeffrey; Zheng, Yiran; Yuan, Jake; Brindle, James; Yao, Min; Lo, Simon; Wessels, Barry; Machtay, Mitchell; Sohn, Jason W., E-mail: jason.sohn@case.edu [Department of Radiation Oncology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106 and University Hospitals of Cleveland, 11100 Euclid Avenue, Cleveland, Ohio 44106 (United States); Sloan, Andrew [Department of Neurosurgery, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106 (United States)

    2014-02-15

    Purpose: Establish and validate a process of accurately irradiating small animals using the CyberKnife G4 System (version 8.5) with treatment plans designed to irradiate a hemisphere of a mouse brain based on microCT scanner images. Methods: These experiments consisted of four parts: (1) building a mouse phantom for intensity modulated radiotherapy (IMRT) quality assurance (QA), (2) proving usability of a microCT for treatment planning, (3) fabricating a small animal positioning system for use with the CyberKnife's image guided radiotherapy (IGRT) system, and (4)in vivo verification of targeting accuracy. A set of solid water mouse phantoms was designed and fabricated, with radiochromic films (RCF) positioned in selected planes to measure delivered doses. After down-sampling for treatment planning compatibility, a CT image set of a phantom was imported into the CyberKnife treatment planning system—MultiPlan (ver. 3.5.2). A 0.5 cm diameter sphere was contoured within the phantom to represent a hemispherical section of a mouse brain. A nude mouse was scanned in an alpha cradle using a microCT scanner (cone-beam, 157 × 149 pixels slices, 0.2 mm longitudinal slice thickness). Based on the results of our positional accuracy study, a planning treatment volume (PTV) was created. A stereotactic body mold of the mouse was “printed” using a 3D printer laying UV curable acrylic plastic. Printer instructions were based on exported contours of the mouse's skin. Positional reproducibility in the mold was checked by measuring ten CT scans. To verify accurate dose delivery in vivo, six mice were irradiated in the mold with a 4 mm target contour and a 2 mm PTV margin to 3 Gy and sacrificed within 20 min to avoid DNA repair. The brain was sliced and stained for analysis. Results: For the IMRT QA using a set of phantoms, the planned dose (6 Gy to the calculation point) was compared to the delivered dose measured via film and analyzed using Gamma analysis (3% and 3 mm

  20. Worlds Fantastic, Worlds Familiar

    Science.gov (United States)

    Buratti, Bonnie J.

    2017-02-01

    Introduction; 1. Mercury: the hottest little place; 2. Venus: an even hotter place; 3. Mars: the abode of life?; 4. Asteroids and comets: sweat the small stuff; 5. Galileo's treasures: worlds of fire and ice; 6. Enceladus: an active iceball in space; 7. Titan: an Earth in deep freeze?; 8. Iapetus and its friends: the weirdest 'planets' in the Solar System; 9. Pluto: the first view of the 'third zone'; 10. Earths above: the search for exoplanets and life in the universe; Epilogue; Glossary; Acknowledgements; Index.

  1. Markerless rat head motion tracking using structured light for brain PET imaging of unrestrained awake small animals

    Science.gov (United States)

    Miranda, Alan; Staelens, Steven; Stroobants, Sigrid; Verhaeghe, Jeroen

    2017-03-01

    Preclinical positron emission tomography (PET) imaging in small animals is generally performed under anesthesia to immobilize the animal during scanning. More recently, for rat brain PET studies, methods to perform scans of unrestrained awake rats are being developed in order to avoid the unwanted effects of anesthesia on the brain response. Here, we investigate the use of a projected structure stereo camera to track the motion of the rat head during the PET scan. The motion information is then used to correct the PET data. The stereo camera calculates a 3D point cloud representation of the scene and the tracking is performed by point cloud matching using the iterative closest point algorithm. The main advantage of the proposed motion tracking is that no intervention, e.g. for marker attachment, is needed. A manually moved microDerenzo phantom experiment and 3 awake rat [18F]FDG experiments were performed to evaluate the proposed tracking method. The tracking accuracy was 0.33 mm rms. After motion correction image reconstruction, the microDerenzo phantom was recovered albeit with some loss of resolution. The reconstructed FWHM of the 2.5 and 3 mm rods increased with 0.94 and 0.51 mm respectively in comparison with the motion-free case. In the rat experiments, the average tracking success rate was 64.7%. The correlation of relative brain regional [18F]FDG uptake between the anesthesia and awake scan reconstructions was increased from on average 0.291 (not significant) before correction to 0.909 (p  <  0.0001) after motion correction. Markerless motion tracking using structured light can be successfully used for tracking of the rat head for motion correction in awake rat PET scans.

  2. Treatment of small cell carcinoma of lung with combined high dose mediastinal irradiation, whole brain prophylaxis and chemotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Shank, B.; Natale, R.B.; Hilaris, B.S.; Wittes, R.E.

    1981-04-01

    Survival of patients with small cell carcinoma of lung, treated on a new combined radiotherapy-chemotherapy protocol, compares favorably with other regimens in the literature and our own previous combined approaches. Radiation, given after induction chemotherapy, consisted of whole brain prophylaxis in all 44 evaluable patients. Patients with limited disease were also treated to the primary and mediastinum to a high dose (5000 rad equivalent) using multiple fields. The new chemotherapy regimen consisted of induction with cyclophosphamide, doxorubicin, and vincristine alternated with cis-platinum and VP-16 (an epipodophyllotoxin) for two cycles, followed by consolidation with low dose cyclophosphamide and vincristine concurrent with irradiation. Patients with limited disease who achieved less than complete response, and all patients with extensive disease were not continued on maintenance chemotherapy. Out of 24 evaluable patients with limited disease, there was 73% survival at 1 year by life-table analysis, measured from treatment initiation. After induction, 16/24 of these limited disease patients were CR (complete responders): 20/24 were CR at completion of their irradiation. Out of 20 evaluable patients with extensive disease, there was 59% survival at 1 year by life-table analysis. Only 4/44 (9%) brain parenchymal relapses occurred, one at 3 months and one at 6 months after local failure and two in patients who did not become CRs, implicating a possible re-seeding mechanism. Five patients had central nervous system relapses outside of brain parenchyma (spinal epidural and leptomeningeal); in three patients this was the initial site of failure. Significant complications included leukopenia (50%) and thrombocytopenia (24%) primarily during induction, and chronic pulmonary fibrosis (25%), possibly contributing to two deaths.

  3. Whole brain radiotherapy in management of non-small-cell lung carcinoma associated leptomeningeal carcinomatosis: evaluation of prognostic factors.

    Science.gov (United States)

    Ozdemir, Yurday; Yildirim, Berna Akkus; Topkan, Erkan

    2016-09-01

    To assess the efficacy of whole-brain radiotherapy (WBRT) and prognostic factors in leptomeningeal carcinomatosis (LMC) of non-small-cell lung cancer (NSCLC) patients. WBRT records of 51 LMC patients confined to brain were reviewed. Eligible patients had squamous-cell carcinoma (SCC) or adenocarcinoma, and Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0-3. The WBRT was either 20 or 30 Gray. The primary and secondary objectives were to determine overall survival (OS) and prognostic factors for improved treatment response, respectively. Median age was 53 years (range 39-68), 58.8 % had SCC, 74.5 % had ECOG PS 1-2, and 70.6 % had LMC accompanied by parenchymal brain metastases (BM). The median follow-up was 4.1 months (range 0.7-14.4); all patients died due to disease progression. Median OS was 3.9 months (95 % CI 3.3-4.5) with 6 and 12 month estimates of 19.6 and 5.9 %, respectively. Evaluation of prognostic factors revealed that patients with ECOG 1, longer time to LMC (TT-LMC) from NSCLC diagnosis (>11.3 months), and absence of parenchymal BM had significantly superior OS than those patients with ECOG 2 (p = 0.01) or 3 (p  11.3 months, and no BM as independent prognosticators for better response to WBRT in NSCLC patients with LMC.

  4. Patient-derived xenografts from non-small cell lung cancer brain metastases are valuable translational platforms for the development of personalized targeted therapy.

    Science.gov (United States)

    Lee, Hye Won; Lee, Jung-Il; Lee, Se Jeong; Cho, Hyun Jung; Song, Hye Jin; Jeong, Da Eun; Seo, Yun Jee; Shin, Sang; Joung, Je-Gun; Kwon, Yong-Jun; Choi, Yoon-La; Park, Woong-Yang; Lee, Hyun Moo; Seol, Ho Jun; Shim, Young Mog; Joo, Kyeung Min; Nam, Do-Hyun

    2015-03-01

    The increasing prevalence of distant metastases from non-small cell lung cancer (NSCLC) indicates an urgent need for novel therapeutic modalities. Brain metastasis is particularly common in NSCLC, with severe adverse effects on clinical prognosis. Although the molecular heterogeneity of NSCLC and availability of various targeted agents suggest personalized therapeutic approaches for such brain metastases, further development of appropriate preclinical models is needed to validate the strategies. We established patient-derived xenografts (PDX) using NSCLC brain metastasis surgical samples and elucidated their possible preclinical and clinical implications for personalized treatment. NSCLC brain metastases (n = 34) showed a significantly higher successful PDX establishment rate than primary specimens (n = 64; 74% vs. 23%). PDXs derived from NSCLC brain metastases recapitulated the pathologic, genetic, and functional properties of corresponding parental tumors. Furthermore, tumor spheres established in vitro from the xenografts under serum-free conditions maintained their in vivo brain metastatic potential. Differential phenotypic and molecular responses to 20 targeted agents could subsequently be screened in vitro using these NSCLC PDXs derived from brain metastases. Although PDX establishment from primary NSCLCs was significantly influenced by histologic subtype, clinical aggressiveness, and genetic alteration status, the brain metastases exhibited consistently adequate in vivo tumor take rate and in vitro tumor sphere formation capacity, regardless of clinical and molecular conditions. Therefore, PDXs from NSCLC brain metastases may better represent the heterogeneous advanced NSCLC population and could be utilized as preclinical models to meet unmet clinical needs such as drug screening for personalized treatments. ©2014 American Association for Cancer Research.

  5. Modality-independent representations of small quantities based on brain activation patterns.

    Science.gov (United States)

    Damarla, Saudamini Roy; Cherkassky, Vladimir L; Just, Marcel Adam

    2016-04-01

    Machine learning or MVPA (Multi Voxel Pattern Analysis) studies have shown that the neural representation of quantities of objects can be decoded from fMRI patterns, in cases where the quantities were visually displayed. Here we apply these techniques to investigate whether neural representations of quantities depicted in one modality (say, visual) can be decoded from brain activation patterns evoked by quantities depicted in the other modality (say, auditory). The main finding demonstrated, for the first time, that quantities of dots were decodable by a classifier that was trained on the neural patterns evoked by quantities of auditory tones, and vice-versa. The representations that were common across modalities were mainly right-lateralized in frontal and parietal regions. A second finding was that the neural patterns in parietal cortex that represent quantities were common across participants. These findings demonstrate a common neuronal foundation for the representation of quantities across sensory modalities and participants and provide insight into the role of parietal cortex in the representation of quantity information.

  6. A High-Content Larval Zebrafish Brain Imaging Method for Small Molecule Drug Discovery

    Science.gov (United States)

    Liu, Harrison; Chen, Steven; Huang, Kevin; Kim, Jeffrey; Mo, Han; Iovine, Raffael; Gendre, Julie; Pascal, Pauline; Li, Qiang; Sun, Yaping; Dong, Zhiqiang; Arkin, Michelle; Guo, Su

    2016-01-01

    Drug discovery in whole-organisms such as zebrafish is a promising approach for identifying biologically-relevant lead compounds. However, high content imaging of zebrafish at cellular resolution is challenging due to the difficulty in orienting larvae en masse such that the cell type of interest is in clear view. We report the development of the multi-pose imaging method, which uses 96-well round bottom plates combined with a standard liquid handler to repose the larvae within each well multiple times, such that an image in a specific orientation can be acquired. We have validated this method in a chemo-genetic zebrafish model of dopaminergic neuron degeneration. For this purpose, we have developed an analysis pipeline that identifies the larval brain in each image and then quantifies neuronal health in CellProfiler. Our method achieves a SSMD* score of 6.96 (robust Z’-factor of 0.56) and is suitable for screening libraries up to 105 compounds in size. PMID:27732643

  7. A neonatal piglet model for investigating brain and cognitive development in small for gestational age human infants.

    Science.gov (United States)

    Radlowski, Emily C; Conrad, Matthew S; Lezmi, Stephane; Dilger, Ryan N; Sutton, Brad; Larsen, Ryan; Johnson, Rodney W

    2014-01-01

    The piglet was investigated as a potential model for studying brain and cognitive deficits associated with being born small for gestational age (SGA). Naturally farrowed SGA (0.7-1.0 kg BW) and average for gestational age (AGA, 1.3-1.6 kg BW) piglets were obtained on postnatal day (PD) 2, placed in individual cages, and provided a nutritionally adequate milk replacer diet (285 ml/kg/d). Beginning at PD14, performance in a spatial T-maze task was assessed. At PD28, piglets were anesthetized for magnetic resonance (MR) imaging to assess brain structure (voxel-based morphometry), connectivity (diffusion-tensor imaging) and metabolites in the hippocampus and corpus callosum (proton MR spectroscopy). Piglets born SGA showed compensatory growth such that BW of SGA and AGA piglets was similar (P>0.05), by PD15. Birth weight affected maze performance, with SGA piglets taking longer to reach criterion than AGA piglets (pdevelopment and connectivity. None of the metabolites measured were different between groups. Collectively, the results show that SGA piglets have spatial learning deficits and abnormal development of white matter. As learning deficits and abnormalities in white matter are common in SGA human infants, the piglet is a tractable translational model that can be used to investigate SGA-associated cognitive deficits and potential interventions.

  8. The Small-Molecule TrkB Agonist 7, 8-Dihydroxyflavone Decreases Hippocampal Newborn Neuron Death After Traumatic Brain Injury.

    Science.gov (United States)

    Chen, Liang; Gao, Xiang; Zhao, Shu; Hu, Weipeng; Chen, Jinhui

    2015-06-01

    Previous studies in rodents have shown that after a moderate traumatic brain injury (TBI) with a controlled cortical impact (CCI) device, the adult-born immature granular neurons in the dentate gyrus are the most vulnerable cell type in the hippocampus. There is no effective approach for preventing immature neuron death after TBI. We found that tyrosine-related kinase B (TrkB), a receptor of brain-derived neurotrophic factor (BDNF), is highly expressed in adult-born immature neurons. We determined that the small molecule imitating BDNF, 7, 8-dihydroxyflavone (DHF), increased phosphorylation of TrkB in immature neurons both in vitro and in vivo. Pretreatment with DHF protected immature neurons from excitotoxicity-mediated death in vitro, and systemic administration of DHF before moderate CCI injury reduced the death of adult-born immature neurons in the hippocampus 24 hours after injury. By contrast, inhibiting BDNF signaling using the TrkB antagonist ANA12 attenuated the neuroprotective effects of DHF. These data indicate that DHF may be a promising chemical compound that promotes immature neuron survival after TBI through activation of the BDNF signaling pathway.

  9. Diffusion tensor and volumetric magnetic resonance measures as biomarkers of brain damage in a small animal model of HIV.

    Directory of Open Access Journals (Sweden)

    Margaret R Lentz

    Full Text Available There are currently no widely accepted neuro-HIV small animal models. We wanted to validate the HIV-1 Transgenic rat (Tg as an appropriate neuro-HIV model and then establish in vivo imaging biomarkers of neuropathology, within this model, using MR structural and diffusion tensor imaging (DTI.Young and middle-aged Tg and control rats were imaged using MRI. A subset of middle-aged animals underwent longitudinal repeat imaging six months later. Total brain volume (TBV, ventricular volume (VV and parenchymal volume (PV = TBV-VV were measured. Fractional anisotropy (FA and mean diffusivity (MD values of the corpus callosum (CC were calculated from DTI data.TBV and PV were smaller in Tg compared to control rats in young and middle-aged cohorts (p0.05.We detected brain volume loss in the Tg rat, probably due to astrocytic dysfunction/loss, loss of structural/axonal matrix and striatal neuronal loss as suggested by immunofluorescence. Increased MD and decreased FA in the CC probably reflect microstructural differences between the Tg and Control rats which could include increased extracellular space between white matter tracts, demyelination and axonal degeneration, among other pathologies. We believe that the Tg rat is an adequate model of neuropathology in HIV and that volumetric MR and DTI measures can be potentially used as biomarkers of disease progression.

  10. Acute onset of brain atrophy and dementia in a patient with small cell lung cancer: a case report.

    Science.gov (United States)

    Asano, Michiko; Fujimoto, Nobukazu; Gemba, Kenichi; Wada, Sae; Ono, Katsuichiro; Ozaki, Shinji; Adachi, Yoshiaki; Yamamoto, Hiromichi; Kishimoto, Takumi

    2011-03-01

    A 59-year-old man who was diagnosed with small cell lung cancer (SCLC), achieved a complete response to the induction chemoradiotherapy and received prophylactic cranial irradiation (PCI) (25 Gy at 250 cGy per fraction) in October 2008. Three months later, he complained of anorexia, weight loss, fatigue, and short-term memory loss and developed dementia and systemic muscle weakness. Magnetic resonance imaging in April and July 2009 revealed the progression of the diffuse brain atrophy without evidence of the metastasis of SCLC. Paraneoplastic neurological syndrome was suspected because anti-Hu antibody was detected in his serum and cerebrospinal fluid, but the adverse effects of chemotherapy and/or radiotherapy were also suspected as the cause of his neurological disorder.

  11. Combining small-volume metabolomic and transcriptomic approaches for assessing brain chemistry.

    Science.gov (United States)

    Knolhoff, Ann M; Nautiyal, Katherine M; Nemes, Peter; Kalachikov, Sergey; Morozova, Irina; Silver, Rae; Sweedler, Jonathan V

    2013-03-19

    The integration of disparate data types provides a more complete picture of complex biological systems. Here we combine small-volume metabolomic and transcriptomic platforms to determine subtle chemical changes and to link metabolites and genes to biochemical pathways. Capillary electrophoresis-mass spectrometry (CE-MS) and whole-genome gene expression arrays, aided by integrative pathway analysis, were utilized to survey metabolomic/transcriptomic hippocampal neurochemistry. We measured changes in individual hippocampi from the mast cell mutant mouse strain, C57BL/6 Kit(W-sh/W-sh). These mice have a naturally occurring mutation in the white spotting locus that causes reduced c-Kit receptor expression and an inability of mast cells to differentiate from their hematopoietic progenitors. Compared with their littermates, the mast cell-deficient mice have profound deficits in spatial learning, memory, and neurogenesis. A total of 18 distinct metabolites were identified in the hippocampus that discriminated between the C57BL/6 Kit(W-sh/W-sh) and control mice. The combined analysis of metabolite and gene expression changes revealed a number of altered pathways. Importantly, results from both platforms indicated that multiple pathways are impacted, including amino acid metabolism, increasing the confidence in each approach. Because the CE-MS and expression profiling are both amenable to small-volume analysis, this integrated analysis is applicable to a range of volume-limited biological systems.

  12. Risk Factors for Brain Metastases in Locally Advanced Non-Small Cell Lung Cancer With Definitive Chest Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Zhe; Bi, Nan; Wang, Jingbo; Hui, Zhouguang; Xiao, Zefen; Feng, Qinfu; Zhou, Zongmei; Chen, Dongfu; Lv, Jima; Liang, Jun; Fan, Chengcheng; Liu, Lipin; Wang, Luhua, E-mail: wlhwq@yahoo.com

    2014-06-01

    Purpose: We intended to identify risk factors that affect brain metastases (BM) in patients with locally advanced non-small cell lung cancer (LA-NSCLC) receiving definitive radiation therapy, which may guide the choice of selective prevention strategies. Methods and Materials: The characteristics of 346 patients with stage III NSCLC treated with thoracic radiation therapy from January 2008 to December 2010 in our institution were retrospectively reviewed. BM rates were analyzed by the Kaplan-Meier method. Multivariate Cox regression analysis was performed to determine independent risk factors for BM. Results: The median follow-up time was 48.3 months in surviving patients. A total of 74 patients (21.4%) experienced BM at the time of analysis, and for 40 (11.7%) of them, the brain was the first site of failure. The 1-year and 3-year brain metastasis rates were 15% and 28.1%, respectively. In univariate analysis, female sex, age ≤60 years, non-squamous cell carcinoma, T3-4, N3, >3 areas of lymph node metastasis, high lactate dehydrogenase and serum levels of tumor markers (CEA, NSE, CA125) before treatment were significantly associated with BM (P<.05). In multivariate analysis, age ≤60 years (P=.004, hazard ratio [HR] = 0.491), non-squamous cell carcinoma (P=.000, HR=3.726), NSE >18 ng/mL (P=.008, HR=1.968) and CA125 ≥ 35 U/mL (P=.002, HR=2.129) were independent risk factors for BM. For patients with 0, 1, 2, and 3 to 4 risk factors, the 3-year BM rates were 7.3%, 18.9%, 35.8%, and 70.3%, respectively (P<.001). Conclusions: Age ≤60 years, non-squamous cell carcinoma, serum NSE >18 ng/mL, and CA125 ≥ 35 U/mL were independent risk factors for brain metastasis. The possibilities of selectively using prophylactic cranial irradiation in higher-risk patients with LA-NSCLC should be further explored in the future.

  13. Long-Term Survival in a Patient with Multiple Brain Metastases from Small-Cell Lung Cancer Treated with Gamma Knife Radiosurgery on Four Occasions: A Case Report

    Directory of Open Access Journals (Sweden)

    Ameer L. Elaimy

    2012-01-01

    Full Text Available Brain metastases are the most common cancerous neoplasm in the brain. The treatment of these lesions is challenging and often includes a multimodality management approach with whole-brain radiation therapy, stereotactic radiosurgery, and neurosurgery options. Although advances in biomedical imaging technologies and the treatment of extracranial cancer have led to the overall increase in the survival of brain metastases patients, the finding that select patients survive several years remains puzzling. For this reason, we present the case of a 70-year-old patient who was diagnosed with multiple brain metastases from small-cell lung cancer five years ago and is currently alive following treatment with chemotherapy for the primary cancer and whole-brain radiation therapy and Gamma Knife radiosurgery on four separate occasions for the neurological cancer. Since the diagnosis of brain metastases five years ago, the patient’s primary cancer has remained controlled. Furthermore, multiple repeat GKRS procedures provided this patient with high levels of local tumor control, which in combination with a stable primary cancer led to an extended period of survival and a highly functional life. Further analysis and clinical research will be valuable in assessing the durability of multiple GKRS for brain metastases patients who experience long-term survival.

  14. Incidence of Brain Metastases on Follow-up (18)F-FDG PET/CT Scans of Non-Small Cell Lung Cancer Patients: Should We Include the Brain?

    Science.gov (United States)

    Nia, Emily S; Garland, Linda L; Eshghi, Naghmehossadat; Nia, Benjamin B; Avery, Ryan J; Kuo, Phillip H

    2017-09-01

    The brain is the most common site of distant metastasis from lung cancer. Thus, MRI of the brain at initial staging is routinely performed, but if this examination is negative a follow-up examination is often not performed. This study evaluates the incidence of asymptomatic brain metastases in non-small cell lung cancer patients detected on follow-up (18)F-FDG PET/CT scans. Methods: In this Institutional Review Board-approved retrospective review, all vertex to thigh (18)F-FDG PET/CT scans in patients with all subtypes of lung cancer from August 2014 to August 2016 were reviewed. A total of 1,175 (18)F-FDG PET/CT examinations in 363 patients were reviewed. Exclusion criteria included brain metastases on initial staging, histologic subtype of small-cell lung cancer, and no follow-up (18)F-FDG PET/CT examinations. After our exclusion criteria were applied, a total of 809 follow-up (18)F-FDG PET/CT scans in 227 patients were included in the final analysis. The original report of each (18)F-FDG PET/CT study was reviewed for the finding of brain metastasis. The finding of a new brain metastasis prompted a brain MRI, which was reviewed to determine the accuracy of the (18)F-FDG PET/CT. Results: Five of 227 patients with 809 follow-up (18)F-FDG PET/CT scans reviewed were found to have incidental brain metastases. The mean age of the patients with incidental brain metastasis was 68 y (range, 60-77 y). The mean time from initial diagnosis to time of detection of incidental brain metastasis was 36 mo (range, 15-66 mo). When MRI was used as the gold standard, our false-positive rate was zero. Conclusion: By including the entire head during follow-up (18)F-FDG PET/CT scans of patients with non-small cell lung cancer, brain metastases can be detected earlier while still asymptomatic. But, given the additional scan time, radiation, and low incidence of new brain metastases in asymptomatic patients, the cost-to-benefit ratio should be weighed by each institution. © 2017 by the

  15. Appetite control and energy balance regulation in the modern world: reward-driven brain overrides repletion signals.

    Science.gov (United States)

    Zheng, H; Lenard, N R; Shin, A C; Berthoud, H-R

    2009-06-01

    Powerful biological mechanisms evolved to defend adequate nutrient supply and optimal levels of body weight/adiposity. Low levels of leptin indicating food deprivation and depleted fat stores have been identified as the strongest signals to induce adaptive biological actions such as increased energy intake and reduced energy expenditure. In concert with other signals from the gut and metabolically active tissues, low leptin levels trigger powerful activation of multiple peripheral and brain systems to restore energy balance. It is not just neurons in the arcuate nucleus, but many other brain systems involved in finding potential food sources, smelling and tasting food, and learning to maximize rewarding effects of foods, that are affected by low leptin. Food restriction and fat depletion thus lead to a 'hungry' brain, preoccupied with food. By contrast, because of less (adaptive thrifty fuel efficiency) or lost (lack of predators) evolutionary pressure, the upper limits of body weight/adiposity are not as strongly defended by high levels of leptin and other signals. The modern environment is characterized by the increased availability of large amounts of energy-dense foods and increased presence of powerful food cues, together with minimal physical procurement costs and a sedentary lifestyle. Much of these environmental influences affect cortico-limbic brain areas concerned with learning and memory, reward, mood and emotion. Common obesity results when individual predisposition to deal with a restrictive environment, as engraved by genetics, epigenetics and/or early life experience, is confronted with an environment of plenty. Therefore, increased adiposity in prone individuals should be seen as a normal physiological response to a changed environment, not in the pathology of the regulatory system. The first line of defense should ideally lie in modifications to the environment and lifestyle. However, as such modifications will be slow and incomplete, it is equally

  16. The world of physics a small library of the literature of physics from antiquity to the present

    CERN Document Server

    Weaver, Jefferson H

    1987-01-01

    Thirty-one years ago Simon & Schuster published James R. Newman's excellent The World of Mathematics. The present anthology on physics is much along the same lines. Most of the pages are devoted to excerpts from over 100 of the most important writers on physics topics. Each item is preceded by editorial commentary. The selections avoid extensive use of mathematics; they are accessible to nonspecialists but are by no means "easy reading." The editorial comments are generally helpful, although errors and omissions are occasionally conspicuous. The first half of volume 1 is perhaps overweighted with the ideas of ancient and medieval thinkers, not all of whom were closely tied to the development of physical science. Nevertheless, the set as a whole provides an enjoyable and comprehensive look at physics.

  17. Activation of brain B-Raf protein kinase by Rap1B small GTP-binding protein.

    Science.gov (United States)

    Ohtsuka, T; Shimizu, K; Yamamori, B; Kuroda, S; Takai, Y

    1996-01-19

    Rap1 small GTP-binding protein has the same amino acid sequence at its effector domain as that of Ras. Rap1 has been shown to antagonize the Ras functions, such as the Ras-induced transformation of NIH 3T3 cells and the Ras-induced activation of the c-Raf-1 protein kinase-dependent mitogen-activated protein (MAP) kinase cascade in Rat-1 cells, whereas we have shown that Rap1 as well as Ras stimulates DNA synthesis in Swiss 3T3 cells. We have established a cell-free assay system in which Ras activates bovine brain B-Raf protein kinase. Here we have used this assay system and examined the effect of Rap1 on the B-Raf activity to phosphorylate recombinant MAP kinase kinase (MEK). Recombinant Rap1B stimulated the activity of B-Raf, which was partially purified from bovine brain and immunoprecipitated by an anti-B-Raf antibody. The GTP-bound form was active, but the GDP-bound form was inactive. The fully post-translationally lipid-modified form was active, but the unmodified form was nearly inactive. The maximum B-Raf activity stimulated by Rap1B was nearly the same as that stimulated by Ki-Ras. Rap1B enhanced the Ki-Ras-stimulated B-Raf activity in an additive manner. These results indicate that not only Ras but also Rap1 is involved in the activation of the B-Raf-dependent MAP kinase cascade.

  18. Sustaining “Lilliputs” in the Global Knowledge-Based Economy: Prospects for Micro, Small, and Medium-Scale Enterprises in the Developing World

    Directory of Open Access Journals (Sweden)

    Maria Divina Gracia Z. Roldan

    2015-06-01

    Full Text Available Micro, small, and medium-scale enterprises (MSMEs comprise bulk of business entities in the developing world. Their contribution is seen in terms of employment generation and capital formation. Seen as the engine of growth in present knowledge-based economies, MSMEs play a crucial role in the economic sustainability of Asian developing countries. This paper discusses the role of MSMEs in Asia, with the Philippines as a case in point. It examines issues and challenges these enterprises face, as well as, their role and impact in developing the Philippine economy and human capital. It explores mechanisms of European linkaging and assistance to the Philippine MSME sector. The paper posits that a supportive policy environment is necessary for these enterprises to achieve their potential for sustainable growth in a global knowledge-based economy. Keywords: Sustainability, micro, small & medium-scale enterprises, knowledge-based economy, European linkaging mechanisms

  19. Vorinostat and Concurrent Stereotactic Radiosurgery for Non-Small Cell Lung Cancer Brain Metastases: A Phase 1 Dose Escalation Trial.

    Science.gov (United States)

    Choi, Clara Y H; Wakelee, Heather A; Neal, Joel W; Pinder-Schenck, Mary C; Yu, Hsiang-Hsuan Michael; Chang, Steven D; Adler, John R; Modlin, Leslie A; Harsh, Griffith R; Soltys, Scott G

    2017-09-01

    To determine the maximum tolerated dose (MTD) of vorinostat, a histone deacetylase inhibitor, given concurrently with stereotactic radiosurgery (SRS) to treat non-small cell lung cancer (NSCLC) brain metastases. Secondary objectives were to determine toxicity, local failure, distant intracranial failure, and overall survival rates. In this multicenter study, patients with 1 to 4 NSCLC brain metastases, each ≤2 cm, were enrolled in a phase 1, 3 + 3 dose escalation trial. Vorinostat dose levels were 200, 300, and 400 mg orally once daily for 14 days. Single-fraction SRS was delivered on day 3. A dose-limiting toxicity (DLT) was defined as any Common Terminology Criteria for Adverse Events version 3.0 grade 3 to 5 acute nonhematologic adverse event related to vorinostat or SRS occurring within 30 days. From 2009 to 2014, 17 patients were enrolled and 12 patients completed study treatment. Because no DLTs were observed, the MTD was established as 400 mg. Acute adverse events were reported by 10 patients (59%). Five patients discontinued vorinostat early and withdrew from the study. The most common reasons for withdrawal were dyspnea (n=2), nausea (n=1), and fatigue (n=2). With a median follow-up of 12 months (range, 1-64 months), Kaplan-Meier overall survival was 13 months. There were no local failures. One patient (8%) at the 400-mg dose level with a 2.0-cm metastasis developed histologically confirmed grade 4 radiation necrosis 2 months after SRS. The MTD of vorinostat with concurrent SRS was established as 400 mg. Although no DLTs were observed, 5 patients withdrew before completing the treatment course, a result that emphasizes the need for supportive care during vorinostat administration. There were no local failures. A larger, randomized trial may evaluate both the tolerability and potential local control benefit of vorinostat concurrent with SRS for brain metastases. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Predictors of Individual Tumor Local Control After Stereotactic Radiosurgery for Non-Small Cell Lung Cancer Brain Metastases

    Energy Technology Data Exchange (ETDEWEB)

    Garsa, Adam A. [Department of Radiation Oncology, University of California, San Francisco, San Francisco, California (United States); Badiyan, Shahed N.; DeWees, Todd; Simpson, Joseph R.; Huang, Jiayi; Drzymala, Robert E. [Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri (United States); Barani, Igor J. [Department of Radiation Oncology, University of California, San Francisco, San Francisco, California (United States); Dowling, Joshua L.; Rich, Keith M.; Chicoine, Michael R.; Kim, Albert H.; Leuthardt, Eric C. [Department of Neurosurgery, Washington University School of Medicine, St. Louis, Missouri (United States); Robinson, Clifford G., E-mail: crobinson@radonc.wustl.edu [Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri (United States)

    2014-10-01

    Purpose: To evaluate local control rates and predictors of individual tumor local control for brain metastases from non-small cell lung cancer (NSCLC) treated with stereotactic radiosurgery (SRS). Methods and Materials: Between June 1998 and May 2011, 401 brain metastases in 228 patients were treated with Gamma Knife single-fraction SRS. Local failure was defined as an increase in lesion size after SRS. Local control was estimated using the Kaplan-Meier method. The Cox proportional hazards model was used for univariate and multivariate analysis. Receiver operating characteristic analysis was used to identify an optimal cutpoint for conformality index relative to local control. A P value <.05 was considered statistically significant. Results: Median age was 60 years (range, 27-84 years). There were 66 cerebellar metastases (16%) and 335 supratentorial metastases (84%). The median prescription dose was 20 Gy (range, 14-24 Gy). Median overall survival from time of SRS was 12.1 months. The estimated local control at 12 months was 74%. On multivariate analysis, cerebellar location (hazard ratio [HR] 1.94, P=.009), larger tumor volume (HR 1.09, P<.001), and lower conformality (HR 0.700, P=.044) were significant independent predictors of local failure. Conformality index cutpoints of 1.4-1.9 were predictive of local control, whereas a cutpoint of 1.75 was the most predictive (P=.001). The adjusted Kaplan-Meier 1-year local control for conformality index ≥1.75 was 84% versus 69% for conformality index <1.75, controlling for tumor volume and location. The 1-year adjusted local control for cerebellar lesions was 60%, compared with 77% for supratentorial lesions, controlling for tumor volume and conformality index. Conclusions: Cerebellar tumor location, lower conformality index, and larger tumor volume were significant independent predictors of local failure after SRS for brain metastases from NSCLC. These results warrant further investigation in a prospective

  1. Factors Affecting the Risk of Brain Metastasis in Small Cell Lung Cancer With Surgery: Is Prophylactic Cranial Irradiation Necessary for Stage I-III Disease?

    Energy Technology Data Exchange (ETDEWEB)

    Gong Linlin; Wang, Q.I.; Zhao Lujun; Yuan Zhiyong; Li Ruijian [Department of Radiotherapy, Tianjin Medical University Cancer Institute and Hospital, and Tianjin Key Laboratory of Cancer Prevention and Therapy, Tianjin (China); Wang Ping, E-mail: Doctorwang66@yahoo.cn [Department of Radiotherapy, Tianjin Medical University Cancer Institute and Hospital, and Tianjin Key Laboratory of Cancer Prevention and Therapy, Tianjin (China)

    2013-01-01

    Purpose: The use of prophylactic cranial irradiation (PCI) in small cell lung cancer (SCLC) with surgical resection has not been fully identified. This study undertook to assess the factors affecting the risk of brain metastases in patients with stage I-III SCLC after surgical resection. The implications of PCI treatment for these patients are discussed. Methods and Materials: One hundred twenty-six patients treated with surgical resection for stage I-III SCLC from January 1998-December 2009 were retrospectively analyzed to elucidate the risk factors of brain metastases. Log-rank test and Cox regression model were used to determine the risk factors of brain metastases. Results: The median survival time for this patient population was 34 months, and the 5-year overall survival rate was 34.9%. For the whole group, 23.0% (29/126) of the patients had evidence of metastases to brain. Pathologic stage not only correlated with overall survival but also significantly affected the risk of brain metastases. The 5-year survival rates for patients with pathologic stages I, II, and III were 54.8%, 35.6%, and 14.1%, respectively (P=.001). The frequency of brain metastases in patients with pathologic stages I, II, and III were 6.25% (2/32), 28.2% (11/39), and 29.1% (16/55) (P=.026), respectively. A significant difference in brain metastases between patients with complete resection and incomplete resection was also observed (20.5% vs 42.9%, P=.028). The frequency of brain metastases was not found to be correlated with age, sex, pathologic type, induction chemotherapy, adjuvant chemotherapy, or adjuvant radiation therapy. Conclusions: Stage I SCLC patients with complete resection had a low incidence of brain metastases and a favorable survival rate. Stage II-III disease had a higher incidence of brain metastases. Thus, PCI might have a role for stage II-III disease but not for stage I disease.

  2. The role of microRNA-21 in predicting brain metastases from non-small cell lung cancer

    Directory of Open Access Journals (Sweden)

    Dong J

    2016-12-01

    Full Text Available Jing Dong,1 Zhi Zhang,2 Tao Gu,3 Shu-Feng Xu,4 Li-Xin Dong,3 Xin Li,5 Bao-Hong Fu,3 Zhan-Zhao Fu3 1Basic Research for Oncology, North China University of Science and Technology, 2Department of Oncology, Workers’ Hospital of Tangshan City, Tangshan, 3Department of Oncology, 4Department of Respiratory Medicine, The First Hospital of Qinhuangdao City, Qinhuangdao, 5Department of Oncology, Chengde Medical College, Chengde, People’s Republic of China Objective: This study aimed at exploring the role of microRNA-21 (miR-21 in predicting brain metastases (BM from non-small cell lung cancer (NSCLC. Methods: A total of 132 NSCLC patients, including 68 patients with BM and 64 patients without BM, were included in the study. NSCLC cells were collected and assigned to the inhibitor (IN group, the mock group, and the negative control (NC group. The quantitative real-time polymerase chain reaction assay was used to detect the miR-21 expression. Cell proliferation, migration, invasion, and apoptosis were detected by colony-forming assay, MTT assay, transwell assay, and flow cytometry, respectively. Angiogenesis was measured by endothelial cell tube formation assay. Results: The miR-21 expression was higher in NSCLC patients with BM than in those without BM. The miR-21 expression in the IN group was lower than that in the NC and mock groups. Compared with the NC and mock groups, the values of optical density (OD and the colony-forming number decreased in the IN group. Compared with the NC and mock groups, cell invasion and migration abilities significantly reduced in the IN group. The IN group had higher apoptosis rate than the NC and mock groups. The tube length was shorter and the number of junction points was less in the IN group in comparison to the NC and mock groups. Conclusion: miR-21 might be a potential biomarker for the development of BM in NSCLC patients and could promote the proliferation, migration, invasion, and angiogenesis of NSCLC cells

  3. Real world navigation independence in the early blind correlates with differential brain activity associated with virtual navigation.

    Science.gov (United States)

    Halko, Mark A; Connors, Erin C; Sánchez, Jaime; Merabet, Lotfi B

    2014-06-01

    Navigating is a complex cognitive task that places high demands on spatial abilities, particularly in the absence of sight. Significant advances have been made in identifying the neural correlates associated with various aspects of this skill; however, how the brain is able to navigate in the absence of visual experience remains poorly understood. Furthermore, how neural network activity relates to the wide variability in navigational independence and skill in the blind population is also unknown. Using functional magnetic resonance imaging, we investigated the neural correlates of audio-based navigation within a large scale, indoor virtual environment in early profoundly blind participants with differing levels of spatial navigation independence (assessed by the Santa Barbara Sense of Direction scale). Performing path integration tasks in the virtual environment was associated with activation within areas of a core network implicated in navigation. Furthermore, we found a positive relationship between Santa Barbara Sense of Direction scores and activation within right temporal parietal junction during the planning and execution phases of the task. These findings suggest that differential navigational ability in the blind may be related to the utilization of different brain network structures. Further characterization of the factors that influence network activity may have important implications regarding how this skill is taught in the blind community.

  4. Afatinib-refractory brain metastases from EGFR-mutant non-small-cell lung cancer successfully controlled with erlotinib: a case report.

    Science.gov (United States)

    Nonagase, Yoshikane; Okamoto, Kunio; Iwasa, Tsutomu; Yoshida, Takeshi; Tanaka, Kaoru; Takeda, Masayuki; Kaneda, Hiroyasu; Shimizu, Toshio; Tsurutani, Junji; Nakagawa, Kazuhiko

    2016-03-01

    Both afatinib and erlotinib are tyrosine kinase inhibitors that inhibit aberrant epidermal growth factor receptor (EGFR) signals in non-small-cell lung cancer (NSCLC). Afatinib is an irreversible inhibitor directed against EGFR, ErbB-2, and ErbB-4, whereas erlotinib is a reversible inhibitor directed against EGFR only. Although afatinib has been shown to be effective in the treatment for erlotinib-refractory and/or gefitinib-refractory central nervous system metastases from NSCLC, little is known about the efficacy of erlotinib for afatinib-refractory central nervous system metastases. In the present report we describe a case of EGFR mutation-positive NSCLC in which brain metastases developed during first-line afatinib treatment. Whole-brain radiation therapy and substitution of erlotinib for afatinib led to successful shrinkage of the brain metastases. Our report highlights the potential benefit of erlotinib for the management of brain metastases refractory over afatinib in patients with NSCLC.

  5. Minimum Transendothelial Electrical Resistance Thresholds for the Study of Small and Large Molecule Drug Transport in a Human in Vitro Blood-Brain Barrier Model.

    Science.gov (United States)

    Mantle, Jennifer L; Min, Lie; Lee, Kelvin H

    2016-12-05

    A human cell-based in vitro model that can accurately predict drug penetration into the brain as well as metrics to assess these in vitro models are valuable for the development of new therapeutics. Here, human induced pluripotent stem cells (hPSCs) are differentiated into a polarized monolayer that express blood-brain barrier (BBB)-specific proteins and have transendothelial electrical resistance (TEER) values greater than 2500 Ω·cm(2). By assessing the permeabilities of several known drugs, a benchmarking system to evaluate brain permeability of drugs was established. Furthermore, relationships between TEER and permeability to both small and large molecules were established, demonstrating that different minimum TEER thresholds must be achieved to study the brain transport of these two classes of drugs. This work demonstrates that this hPSC-derived BBB model exhibits an in vivo-like phenotype, and the benchmarks established here are useful for assessing functionality of other in vitro BBB models.

  6. Hierarchical Functional Modularity in the Resting-State Human Brain

    NARCIS (Netherlands)

    Ferrarini, Luca; Veer, Ilya M.; Baerends, Evelinda; van Tol, Marie-Jose; Renken, Remco J.; van der Wee, Nic J. A.; Veltman, Dirk. J.; Aleman, Andre; Zitman, Frans G.; Penninx, Brenda W. J. H.; van Buchem, Mark A.; Reiber, Johan H. C.; Rombouts, Serge A. R. B.; Milles, Julien

    2009-01-01

    Functional magnetic resonance imaging (fMRI) studies have shown that anatomically distinct brain regions are functionally connected during the resting state. Basic topological properties in the brain functional connectivity (BFC) map have highlighted the BFC's small-world topology. Modularity, a mor

  7. A split microdrive for simultaneous multi-electrode recordings from two brain areas in awake small animals.

    NARCIS (Netherlands)

    C.S. Lansink; M. Bakker; W. Buster; J. Lankelma; R. van der Blom; R. Westdorp; R.N.J.M.A. Joosten; B.L. Mc.Naughton; C.M.A. Pennartz

    2007-01-01

    Complex cognitive operations such as memory formation and decision-making are thought to be mediated not by single, isolated brain structures but by multiple, connected brain areas. To facilitate studies on the neural communication between connected brain structures, we developed a multi-electrode m

  8. The relevance of serum carcinoembryonic antigen as an indicator of brain metastasis detection in advanced non-small cell lung cancer.

    Science.gov (United States)

    Lee, Dong-Soo; Kim, Yeon-Sil; Jung, So-Lyoung; Lee, Kyo-Young; Kang, Jin-Hyoung; Park, Sarah; Kim, Young-Kyoon; Yoo, Ie-Ryung; Choi, Byung-Ock; Jang, Hong-Seok; Yoon, Sei-Chul

    2012-08-01

    Although many biomarkers have emerged in non-small cell lung cancer (NSCLC), the predictive value of site-specific spread is not fully defined. We designed this study to determine if there is an association between serum biomarkers and brain metastasis in advanced NSCLC. We evaluated 227 eligible advanced NSCLC patients between May 2005 and March 2010. Patients who had been newly diagnosed with stage IV NSCLC but had not received treatment previously, and had available information on at least one of the following pretreatment serum biomarkers were enrolled: carcinoembryonic antigen (CEA), cytokeratin 19 fragments (CYFRA 21-1), cancer antigen 125 (CA 125), cancer antigen 19-9, and squamous cancer cell antigen. Whole body imaging studies and magnetic resonance imaging of the brain were reviewed, and the total number of metastatic regions was scored. Brain metastasis was detected in 66 (29.1%) patients. Although serum CEA, CYFRA 21-1, and CA 125 levels were significantly different between low total metastatic score group (score 1-3) and high total metastatic score group (score 4-7), only CEA level was significantly different between patients with brain metastasis and those without brain metastasis (p present study demonstrated that the pretreatment serum CEA level was significantly correlated with brain metastasis in advanced NSCLC. These findings suggested the possible role of CEA in the pathogenesis of brain invasion. More vigilant surveillance would be warranted in the high-risk group of patients with high serum CEA level and multiple synchronous metastasis.

  9. Outcome of surgical resection for brain metastases and radical treatment of the primary tumor in Chinese non–small-cell lung cancer patients

    Directory of Open Access Journals (Sweden)

    Li Z

    2015-04-01

    Full Text Available Zhenye Li,1,3,* Xiangheng Zhang,1,* Xiaobing Jiang,1 Chengcheng Guo,1 Ke Sai,1 Qunying Yang,1 Zhenqiang He,1 Yang Wang,1 Zhongping Chen,1 Wei Li,2 Yonggao Mou1 1Department of Neurosurgery, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, People’s Republic of China; 2Department of Anesthesiology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, People’s Republic of China; 3Beijing Neurosurgical Institute, Capital Medical University, Beijing, People’s Republic of China *These authors have contributed equally to this work Purpose: Brain metastasis is the most common complication of brain cancer; nevertheless, primary lung cancer accounts for approximately 20%–40% of brain metastases cases. Surgical resection is the preferred treatment for brain metastases. However, no studies have reported the outcome of surgical resection of brain metastases from non–small-cell lung cancer (NSCLC in the People’s Republic of China. Moreover, the optimal treatment for primary NSCLC in patients with synchronous brain metastases is hitherto controversial. Patients and methods: We retrospectively analyzed the cases of NSCLC patients with brain metastases who underwent neurosurgical resection at the Sun Yat-sen University Cancer Center, and assessed the efficacy of surgical resection and the necessity of aggressive treatment for primary NSCLC in synchronous brain metastases patients. Results: A total of 62 patients, including 47 men and 15 women, with brain metastases from NSCLC were enrolled in the study. The median age at the time of craniotomy was 54 years (range 29–76 years. At the final follow-up evaluation, 50 patients had died. The median OS time was 15.1 months, and the survival rates were 70% and 37% at 1 and 2 years, respectively. The median OS

  10. Product retrieval time in small tobacco retail outlets before and after the Australian plain packaging policy: real-world study.

    Science.gov (United States)

    Wakefield, Melanie; Bayly, Megan; Scollo, Michelle

    2014-01-01

    We aimed to assess change in cigarette pack retrieval time in small retail outlets following the introduction of plain packaging in Australia in 1 December 2012. A sample of 303 milk bars, convenience stores, petrol stations and newsagents was selected in four capital cities, stratified by area socioeconomic status. In June and September (baseline months), the first 2 weeks of December 2012, and February 2013, stores were visited by trained fieldworkers who requested a cigarette pack of a pre-determined brand, variant and pack size, unobtrusively recording the time from the end of the request to when the pack was scanned or placed on the counter. In multivariate analysis, December retrieval time (12.43 s) did not differ from June (10.91 s; p=0.410) or February (10.37 s; p=0.382), but was slower than September (9.84 s; p=0.024). In December, retrieval time declined as days after plain packaging implementation increased (β=-0.21, p=0.011), returning to the baseline range by the second week of implementation. This pattern was not observed in baseline months or in February. Sensitivity analyses showed that results were robust to the variability in purchasing circumstances in tobacco retail outlets. Retailers quickly gained experience with the new plain packaging legislation, evidenced by retrieval time having returned to the baseline range by the second week of implementation and remaining so several months later. The long retrieval times predicted by tobacco industry-funded retailer groups and the consequent costs they predicted would fall upon small retailers from plain packaging are unlikely to eventuate.

  11. FID navigator-based MR thermometry method to monitor small temperature changes in the brain of ventilated animals.

    Science.gov (United States)

    Boulant, Nicolas; Bottlaender, Michel; Uhrig, Lynn; Giacomini, Eric; Luong, Michel; Amadon, Alexis; Massire, Aurélien; Larrat, Benoît; Vignaud, Alexandre

    2015-01-01

    An MR thermometry method is proposed for measuring in vivo small temperature changes engendered by external RF heat sources. The method relies on reproducible and stable respiration and therefore currently applies to ventilated animals whose breathing is carefully controlled. It first consists in characterizing the stability of the main magnetic field as well as the variations induced by breathing during a first monitoring stage. Second, RF heating is applied while the phase and thus temperature evolutions are continuously measured, the corrections due to breathing and field drift being made thanks to the data accumulated during the first period. The RF heat source is finally stopped and the temperature rise likewise is continuously monitored during a third and last stage to observe the animal cooling down and to validate the assumptions made for correcting for the main field variation and the physiological noise. Experiments were performed with a clinical 7 T scanner on an anesthetized baboon and with a dedicated RF heating setup. Analysis of the data reveals a precision around 0.1°C, which allows us to reliably measure sub-degree temperature rises in the muscle and in the brain of the animal.

  12. Overexpression of adenylate cyclase-associated protein 1 may predict brain metastasis in non-small cell lung cancer.

    Science.gov (United States)

    Xie, Shuan-Shuan; Tan, Min; Lin, Hai-Yan; Xu, Lei; Shen, Chang-Xing; Yuan, Qing; Song, Xiao-Lian; Wang, Chang-Hui

    2015-01-01

    This study was designed to establish a biomarker risk model for predicting brain metastasis (BM) in non-small cell lung cancer (NSCLC). The model comprises 120 cases of NSCLC that were treated and followed up for 4 years. The patients were divided into the BM (n=50) and non-BM (other visceral metastasis and those without recurrence) (n=70) groups. Immunohistochemical and western blot analyses were performed in metastatic tissues of NSCLC. Multivariate regression analysis was performed to correlate the immunoreactive cyclase-associated protein 1 (CAP1) signal with BM. Survival analyses were performed by using the Kaplan-Meier method. CAP1 protein content and immunoreactivity were significantly increased in BM specimens compared to other-metastatic specimens. The survival analysis revealed that CAP1 overexpression was significantly associated with survival (P<0.05). The ROC test suggested that the area under the curve was 73.33% (P<0.001; 95% CI, 63.5-83.2%). When P=0.466, the sensitivity and specificity reached 79.5 and 67.1%, respectively. These findings suggested that CAP1 is involved in the BM of NSCLC, and that elevated levels of CAP1 expression may indicate a poor prognosis for patients with BM. The CAP1 molecular model may be useful in the prediction of the risk of BM in NSCLC.

  13. Report on the decade of un/esa workshops on basic space science: the international perspective from small astronomical telescopes to the world space observatory

    Science.gov (United States)

    Haubold, H.; Wamsteker, W.

    The UN/ESA Workshops on Basic Space Science is a long-term effort for the development of astronomy and regional and international cooperation in this field on a world wide basis, particularly in developing nations. The first four workshops in this series (India 1991, Costa Rica and Colombia 1992, Nigeria 1993, and Egypt 1994) addressed the status of astronomy in Asia and the Pacific, Latin America and the Caribbean, Africa, and Western Asia, respectively. One major recommendation that emanated from the first four workshops was that small astronomical facilities should be established in developing nations for research and education programmes at the university level and that such facilities should be networked. Subsequently, material for teaching and observational programmes for small optical telescopes were developed or recommended and astronomical telescope facilities have been inaugurated at UN/ESA Workshops on Basic Space Science in Sri Lanka (1995), Honduras (1997), and Jordan (1999). Elements of the Workshops, focusing on teaching, observing programmes, and the Japanese donation programme for small astronomical telescopes are briefly summarized in the first part of this paper. A report on the recent UN/ESA Workshop on Basic Space Science, held at CONAE of Argentina in 2002, and a full report on achievements of the UN/ESA Workshops on Basic Space Science for the period of time from 1991 to 2002 is contained in the second part of this paper. Since 1991, similar reports, issued for each of the UN/ESA Workshops on Basic Space Science, have been brought to the attention of UN Member States on an annual basis with the objective to gain more support for the world wide development of astronomy. WWW: http://www.seas.columbia.edu/~ah297/un-esa/

  14. Big Brains, Small Impact

    Science.gov (United States)

    Jacoby, Russell

    2008-01-01

    Earlier 20th-century thinkers like Lewis Mumford and Edmund Wilson kept the university and its apparatus at arm's length. Indeed, they often disdained it. They oriented themselves toward an educated public, and, as a result, they developed a straightforward prose and gained a nonprofessional audience. As his reputation grew, Wilson printed up a…

  15. Information Diffusion in Small-world Social Networks%小世界社会网络中的信息传播

    Institute of Scientific and Technical Information of China (English)

    唐泳; 马永开

    2006-01-01

    Small-world social network model is one of the best ways to describe the real social system. An information diffusion model was proposed in small-world social networks. In the model, every social participant has a continuous parameter to represents his attitude to the information, and the attitude can be positive or negative and cause positive and negative feedbacks respectively. Concepts of local information and global information were introduced to describe the information acquiring ability of a social participant. Computational experiments of the information diffusion model were also carried in the small-world social networks with different randomness and scales. The simulation results show that the topological structure of the network, the feedbacks caused by the attitudes of the participants and the weight of the global information have great influence on the process that networks evolve into a uniform situation in which all participants hold a same attitude.%小世界社会网络模型是一种描述现实社会系统的理想模型,基于此模型,提出小世界社会网络中的信息传播模型.模型中,每个社会参与者都具有一个连续型参数来描述其对于信息的态度,正的态度对信息传播有正反馈作用,而负的态度对于信息传播有负反馈作用.同时,引入局部信息和全局信息概念用以描速社会参与者对于信息的获取能力.信息传播模型在不同随机度和规模的小世界社会网络上进行了计算仿真.仿真结果表明网络的拓扑结构和参与者态度的正负反馈作用以及对于全局信息的权重对于信息的传播均衡结果有显著的影响.

  16. Brain Aneurysm

    Science.gov (United States)

    A brain aneurysm is an abnormal bulge or "ballooning" in the wall of an artery in the brain. They are sometimes called berry aneurysms because they ... often the size of a small berry. Most brain aneurysms produce no symptoms until they become large, ...

  17. Short-Term Blood Pressure Variability Relates to the Presence of Subclinical Brain Small Vessel Disease in Primary Hypertension.

    Science.gov (United States)

    Filomena, Josefina; Riba-Llena, Iolanda; Vinyoles, Ernest; Tovar, José L; Mundet, Xavier; Castañé, Xavier; Vilar, Andrea; López-Rueda, Antonio; Jiménez-Baladó, Joan; Cartanyà, Anna; Montaner, Joan; Delgado, Pilar

    2015-09-01

    Blood pressure (BP) variability is associated with stroke risk, but less is known about subclinical cerebral small vessel disease (CSVD). We aimed to determine whether CSVD relates to short-term BP variability independently of BP levels and also, whether they improve CSVD discrimination beyond clinical variables and office BP levels. This was a cohort study on asymptomatic hypertensives who underwent brain magnetic resonance imaging and 24-hour ambulatory BP monitoring. Office and average 24-hour, daytime and nighttime BP levels, and several metrics of BP variability (SD, weighted SD, coefficient of variation, and average real variability [ARV]) were calculated. Definition of CSVD was based on the presence of lacunar infarcts and white matter hyperintensity grades. Multivariate analysis and integrated discrimination improvement were performed to assess whether BP variability and levels were independently associated with CSVD and improved its discrimination. Four hundred eighty-seven individuals participated (median age, 64; 47% women). CSVD was identified in 18.9%, related to age, male sex, diabetes mellitus, use of treatment, ambulatory BP monitoring-defined BP levels, and ARV of systolic BP at any period. The highest prevalence (33.7%) was found in subjects with both 24-hour BP levels and ARV elevated. BP levels at any period and ARV (24 hours and nocturnal) emerged as independent predictors of CSVD, and discrimination was incrementally improved although not to a clinically significant extent (integrated discrimination improvement, 5.31%, 5.17% to 5.4%). Ambulatory BP monitoring-defined BP levels and ARV of systolic BP relate to subclinical CSVD in hypertensive individuals.

  18. The role of microRNA-21 in predicting brain metastases from non-small cell lung cancer

    Science.gov (United States)

    Dong, Jing; Zhang, Zhi; Gu, Tao; Xu, Shu-Feng; Dong, Li-Xin; Li, Xin; Fu, Bao-Hong; Fu, Zhan-Zhao

    2017-01-01

    Objective This study aimed at exploring the role of microRNA-21 (miR-21) in predicting brain metastases (BM) from non-small cell lung cancer (NSCLC). Methods A total of 132 NSCLC patients, including 68 patients with BM and 64 patients without BM, were included in the study. NSCLC cells were collected and assigned to the inhibitor (IN) group, the mock group, and the negative control (NC) group. The quantitative real-time polymerase chain reaction assay was used to detect the miR-21 expression. Cell proliferation, migration, invasion, and apoptosis were detected by colony-forming assay, MTT assay, transwell assay, and flow cytometry, respectively. Angiogenesis was measured by endothelial cell tube formation assay. Results The miR-21 expression was higher in NSCLC patients with BM than in those without BM. The miR-21 expression in the IN group was lower than that in the NC and mock groups. Compared with the NC and mock groups, the values of optical density (OD) and the colony-forming number decreased in the IN group. Compared with the NC and mock groups, cell invasion and migration abilities significantly reduced in the IN group. The IN group had higher apoptosis rate than the NC and mock groups. The tube length was shorter and the number of junction points was less in the IN group in comparison to the NC and mock groups. Conclusion miR-21 might be a potential biomarker for the development of BM in NSCLC patients and could promote the proliferation, migration, invasion, and angiogenesis of NSCLC cells.

  19. In vivo imaging of brain dopaminergic neurotransmission system in small animals with high-resolution single photon emission computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Saji, Hideo; Kawashima, Hidekazu; Ogawa, Mikako; Kitamura, Youji; Mukai, Takahiro [Kyoto University, Graduate School of Pharmaceutical Sciences, Kyoto (Japan); Iida, Yasuhiko; Shimazu, Seiichiro; Yoneda, Fumiro [Fujimoto Pharmaceutical Corporation, Matsubara, Osaka (Japan)

    2003-01-01

    High-resolution single photon emission computed tomography (SPECT) provides a unique capability to image the biodistribution of radiolabeled molecules in small laboratory animals. Thus, we applied the high-resolution SPECT to in vivo imaging of the brain dopaminergic neurotransmission system in common marmosets using two radiolabeled ligands, [{sup 123}I]2{beta}-carbomethoxy-3{beta}-(4-iodophenyl)tropane ({beta}-CIT) as a dopamine transporter(DAT) ligand and [{sup 123}I]iodobenzamide (IBZM) as a dopamine D{sub 2} receptor (D{sub 2}R) ligand. Specific images of the striatum, a region with a high density of dopaminergic synapses, were obtained at 240 min and 60 min after injection of [{sup 123}I]{beta}-CIT and [{sup 123}I]IBZM, respectively. Furthermore, a significantly low accumulation of [{sup 123}I]{beta}-CIT in the striatum was observed in MPTP-treated animals compared with results for a control group, and a similar accumulation in the control group was observed with the pretreatment of deprenyl in the MPTP-treated animals. However, the striatal accumulation of [{sup 123}I]IBZM showed no changes among the control, MPTP-treated, and deprenyl-MPTP-treated groups. These SPECT imaging results agreed well with those of DA concentration and motor behavior. Since MPTP destroys nigrostriatal dopamine nerves and produces irreversible neurodegeneration associated with Parkinsonian syndrome, SPECDT imaging data in this study demonstrated that deprenyl shows its neuroprotective effect on Parkinsonism by protecting against the destruction of presynaptic dopamine neutrons. (author)

  20. EGFR and KRAS Mutations Predict the Incidence and Outcome of Brain Metastases in Non-Small Cell Lung Cancer

    Science.gov (United States)

    Tomasini, Pascale; Serdjebi, Cindy; Khobta, Nataliya; Metellus, Philippe; Ouafik, L’Houcine; Nanni, Isabelle; Greillier, Laurent; Loundou, Anderson; Fina, Frederic; Mascaux, Celine; Barlesi, Fabrice

    2016-01-01

    Background: Lung cancer is the leading cause of brain metastases (BM). The identification of driver oncogenes and matched targeted therapies has improved outcome in non-small cell lung cancer (NSCLC) patients; however, a better understanding of BM molecular biology is needed to further drive the process in this field. Methods: In this observational study, stage IV NSCLC patients tested for EGFR and KRAS mutations were selected, and BM incidence, recurrence and patients’ outcome were assessed. Results: A total of 144 patients (142 Caucasian and two Asian) were selected, including 11.27% with EGFR-mutant and 33.10% with KRAS-mutant tumors, and 57.04% patients had developed BM. BM incidence was more frequent in patients with EGFR mutation according to multivariate analyses (MVA) (Odds ratio OR = 8.745 [1.743–43.881], p = 0.008). Among patients with treated BM, recurrence after local treatment was less frequent in patients with KRAS mutation (OR = 0.234 [0.078–0.699], p = 0.009). Among patients with untreated BM, overall survival (OS) was shorter for patients with KRAS mutation according to univariate analysis (OR = 7.130 [1.240–41.012], p = 0.028), but not MVA. Conclusions: EGFR and KRAS mutations have a predictive role on BM incidence, recurrence and outcome in Caucasian NSCLC patients. These results may impact the routine management of disease in these patients. Further studies are required to assess the influence of other biomarkers on NSCLC BM. PMID:27999344

  1. EGFR and KRAS Mutations Predict the Incidence and Outcome of Brain Metastases in Non-Small Cell Lung Cancer

    Directory of Open Access Journals (Sweden)

    Pascale Tomasini

    2016-12-01

    Full Text Available Background: Lung cancer is the leading cause of brain metastases (BM. The identification of driver oncogenes and matched targeted therapies has improved outcome in non-small cell lung cancer (NSCLC patients; however, a better understanding of BM molecular biology is needed to further drive the process in this field. Methods: In this observational study, stage IV NSCLC patients tested for EGFR and KRAS mutations were selected, and BM incidence, recurrence and patients’ outcome were assessed. Results: A total of 144 patients (142 Caucasian and two Asian were selected, including 11.27% with EGFR-mutant and 33.10% with KRAS-mutant tumors, and 57.04% patients had developed BM. BM incidence was more frequent in patients with EGFR mutation according to multivariate analyses (MVA (Odds ratio OR = 8.745 [1.743–43.881], p = 0.008. Among patients with treated BM, recurrence after local treatment was less frequent in patients with KRAS mutation (OR = 0.234 [0.078–0.699], p = 0.009. Among patients with untreated BM, overall survival (OS was shorter for patients with KRAS mutation according to univariate analysis (OR = 7.130 [1.240–41.012], p = 0.028, but not MVA. Conclusions: EGFR and KRAS mutations have a predictive role on BM incidence, recurrence and outcome in Caucasian NSCLC patients. These results may impact the routine management of disease in these patients. Further studies are required to assess the influence of other biomarkers on NSCLC BM.

  2. Risk factors of brain metastases in completely resected pathological stage IIIA-N2 non-small cell lung cancer

    Directory of Open Access Journals (Sweden)

    Ding Xiao

    2012-07-01

    Full Text Available Abstract Background Brain metastases (BM is one of the most common failures of locally advanced non-small cell lung cancer (LA-NSCLC after combined-modality therapy. The outcome of trials on prophylactic cranial irradiation (PCI has prompted us to identify the highest-risk subset most likely to benefit from PCI. Focusing on patients with completely resected pathological stage IIIA-N2 (pIIIA-N2 NSCLC, we aimed to assess risk factors of BM and to define the highest-risk subset. Methods Between 2003 and 2005, the records of 217 consecutive patients with pIIIA-N2 NSCLC in our institution were reviewed. The cumulative incidence of BM was estimated using the Kaplan–Meier method, and differences between the groups were analyzed using log-rank test. Multivariate Cox regression analysis was applied to assess risk factors of BM. Results Fifty-three (24.4 % patients developed BM at some point during their clinical course. On multivariate analysis, non-squamous cell cancer (relative risk [RR]: 4.13, 95 % CI: 1.86–9.19; P = 0.001 and the ratio of metastatic to examined nodes or lymph node ratio (LNR ≥ 30 % (RR: 3.33, 95 % CI: 1.79–6.18; P = 0.000 were found to be associated with an increased risk of BM. In patients with non-squamous cell cancer and LNR ≥ 30 %, the 5-year actuarial risk of BM was 57.3 %. Conclusions In NSCLC, patients with completely resected pIIIA-N2 non-squamous cell cancer and LNR ≥ 30 % are at the highest risk for BM, and are most likely to benefit from PCI. Further studies are warranted to investigate the effect of PCI on this subset of patients.

  3. Different early effect of irradiation in brain and small cell lung cancer examined by in vivo 31P-magnetic resonance spectroscopy

    DEFF Research Database (Denmark)

    Kristjansen, P E; Pedersen, A G; Quistorff, B

    1992-01-01

    Early effects of irradiation were evaluated by non-invasive in vivo 31P-magnetic resonance spectroscopy (31P-MRS) of two small cell lung cancer (SCLC) tumor lines CPH SCCL 54A and 54B, in nude mice. The tumors were originally derived from the same patient and have similar morphology and growth......-MRS. No effect was observed in brain at any dose level. In contrast, 40 Gy induced a statistically significant reduction in ATP/Pi ratio during the 12-h post-irradiation period. This effect was more pronounced in 54A than in 54B. Some reduction was observed following 10 Gy, whereas 2.5 Gy induced no changes...... in ATP/Pi. The differential effect on tumors and brain might be relevant for monitoring irradiation effects by in vivo 31P-MRS in patients with brain metastases....

  4. Small-world networks of residue interactions in the Abl kinase complexes with cancer drugs: topology of allosteric communication pathways can determine drug resistance effects.

    Science.gov (United States)

    Tse, A; Verkhivker, G M

    2015-07-01

    The human protein kinases play a fundamental regulatory role in orchestrating functional processes in complex cellular networks. Understanding how conformational equilibrium between functional kinase states can be modulated by ligand binding or mutations is critical for quantifying molecular basis of allosteric regulation and drug resistance. In this work, molecular dynamics simulations of the Abl kinase complexes with cancer drugs (Imatinib and Dasatinib) were combined with structure-based network modeling to characterize dynamics of the residue interaction networks in these systems. The results have demonstrated that structural architecture of kinase complexes can produce a small-world topology of the interaction networks. Our data have indicated that specific Imatinib binding to a small number of highly connected residues could lead to network-bridging effects and allow for efficient allosteric communication, which is mediated by a dominant pathway sensitive to the unphosphorylated Abl state. In contrast, Dasatinib binding to the active kinase form may activate a broader ensemble of allosteric pathways that are less dependent on the phosphorylation status of Abl and provide a better balance between the efficiency and resilience of signaling routes. Our results have unveiled how differences in the residue interaction networks and allosteric communications of the Abl kinase complexes can be directly related to drug resistance effects. This study offers a plausible perspective on how efficiency and robustness of the residue interaction networks and allosteric pathways in kinase structures may be associated with protein responses to drug binding.

  5. Evaluation of Biomarkers Predictive of Benefit From PD-1 Inhibitor MK-3475 in Patients with Non-Small Cell Lung Cancer and Brain Metastases

    Science.gov (United States)

    2016-07-01

    our purposes (i.e. tissue was obtained via fine needle aspiration and is unable to be cored) or the tissue has already been exhausted. To date we...the PD-1 inhibitor pembrolizumab (MK-3475) in patients with untreated brain metastases from NSCLC (NCT 02085070). The tumor biopsy specimens and blood...to small biopsy samples, and also tissue samples that were previously exhausted. We have screened several hundred patients to find cases that are

  6. Icotinib versus whole-brain irradiation in patients with EGFR-mutant non-small-cell lung cancer and multiple brain metastases (BRAIN): a multicentre, phase 3, open-label, parallel, randomised controlled trial.

    Science.gov (United States)

    Yang, Jin-Ji; Zhou, Caicun; Huang, Yisheng; Feng, Jifeng; Lu, Sun; Song, Yong; Huang, Cheng; Wu, Gang; Zhang, Li; Cheng, Ying; Hu, Chengping; Chen, Gongyan; Zhang, Li; Liu, Xiaoqing; Yan, Hong Hong; Tan, Fen Lai; Zhong, Wenzhao; Wu, Yi-Long

    2017-09-01

    For patients with non-small-cell lung cancer (NSCLC) and multiple brain metastases, whole-brain irradiation (WBI) is a standard-of-care treatment, but its effects on neurocognition are complex and concerning. We compared the efficacy of an epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI), icotinib, versus WBI with or without chemotherapy in a phase 3 trial of patients with EGFR-mutant NSCLC and multiple brain metastases. We did a multicentre, open-label, parallel randomised controlled trial (BRAIN) at 17 hospitals in China. Eligible participants were patients with NSCLC with EGFR mutations, who were naive to treatment with EGFR-TKIs or radiotherapy, and had at least three metastatic brain lesions. We randomly assigned participants (1:1) to either icotinib 125 mg orally (three times per day) or WBI (30 Gy in ten fractions of 3 Gy) plus concurrent or sequential chemotherapy for 4-6 cycles, until unacceptable adverse events or intracranial disease progression occurred. The randomisation was done by the Chinese Thoracic Oncology Group with a web-based allocation system applying the Pocock and Simon minimisation method; groups were stratified by EGFR gene mutation status, treatment line (first line or second line), brain metastases only versus both intracranial and extracranial metastases, and presence or absence of symptoms of intracranial hypertension. Clinicians and patients were not masked to treatment assignment, but individuals involved in the data analysis did not participate in the treatments and were thus masked to allocation. Patients receiving icotinib who had intracranial progression only were switched to WBI plus either icotinib or chemotherapy until further progression; those receiving icotinib who had extracranial progression only were switched to icotinib plus chemotherapy. Patients receiving WBI who progressed were switched to icotinib until further progression. Icotinib could be continued beyond progression if a clinical benefit

  7. Commentary: Treatment Considerations for Patients With Epidermal Growth Factor Receptor-Mutated Non-Small Cell Lung Cancer Brain Metastases in the Era of Tyrosine Kinase Inhibitors.

    Science.gov (United States)

    Vaca, Silvia Daniela; Connolly, Ian David; Ho, Clement; Neal, Joel; Hayden Gephart, Melanie

    2017-08-12

    Brain metastasis is a serious complication of non-small cell lung cancer (NSCLC) affecting up to 40% of NSCLC patients. A subset of NSCLC tumors has mutations in the epidermal growth factor receptor (EGFR) gene, and determination of tumor EGFR mutation status is essential in guiding treatment decisions, as it directly affects the treatment approach. Patients with EGFR-mutated NSCLC have a higher cumulative incidence of brain metastases, and are especially sensitive to EGFR tyrosine kinase inhibitors (TKIs). Patients with newly diagnosed EGFR-mutated lung cancer presenting to a neurosurgeon with a new diagnosis of brain metastases now have a variety of treatment options available, including whole brain radiation therapy, stereotactic radiosurgery, surgical resection, chemotherapy, and targeted therapeutics such as the EGFR TKIs. In this review, we discuss the impact of EGFR mutation status on brain and leptomeningeal metastasis treatment considerations. Additionally, we present clinical cases of patients treated with EGFR TKIs alone and in combination with other therapies to highlight treatment alternatives. Copyright © 2017 by the Congress of Neurological Surgeons.

  8. Clinical Experience with First-generation Epidermal Growth Factor Receptor 
Tyrosine Kinase Inhibitors in Non-small Cell Lung Cancer Patients 
with Brain Metastasis

    Directory of Open Access Journals (Sweden)

    Huixing DONG

    2017-02-01

    Full Text Available Background and objective A survival analysis and the influencing factors for non-small cell lung cancer (NSCLC patients with brain metastases accepting first-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKIs treatment have not yet been elucidated to date. In this study, we collected and analyzed the survival data of NSCLC patients with brain metastasis to obtain evidence and to provide guidance in clinical practice. Methods NSCLC patients with brain metastases who were treated with first-generation EGFR-TKIs were retrospectively collected in 2012-2013 from Shanghai Chest Hospital, Shanghai Jiao Tong University. The Kaplan-Meier method and Cox regression were performed for univariate and multivariate analyses, respectively, to explore the independent predictors influencing the survival of patients with NSCLC brain metastases. Results The median progression-free survival (PFS and median overall survival (OS of all patients treated with first-generation EGFR-TKIs were 10.0 months (95%CI: 8.3-11.7 and 28.0 months (95%CI: 22.9-33.1, respectively. Pathological subtypes were the independent predictors of PFS (P=0.001, and tumor differentiations were the independent predictors of OS (P=0.050. Conclusion First-generation EGFR-TKIs showed promising efficacy in NSCLC patients with brain metastases. PFS was longer in patients with adenocarcinoma than in those with a non-adenocarcinoma subtype. OS was longer in patients with differentiated tumors than in those who developed poorly differentiated tumors.

  9. Gamma knife stereotactic radiosurgery as salvage therapy after failure of whole-brain radiotherapy in patients with small-cell lung cancer.

    Science.gov (United States)

    Harris, Sunit; Chan, Michael D; Lovato, James F; Ellis, Thomas L; Tatter, Stephen B; Bourland, J Daniel; Munley, Michael T; deGuzman, Allan F; Shaw, Edward G; Urbanic, James J; McMullen, Kevin P

    2012-05-01

    Radiosurgery has been successfully used in selected cases to avoid repeat whole-brain irradiation (WBI) in patients with multiple brain metastases of most solid tumor histological findings. Few data are available for the use of radiosurgery for small-cell lung cancer (SCLC). Between November 1999 and June 2009, 51 patients with SCLC and previous WBI and new brain metastases were treated with GammaKnife stereotactic radiosurgery (GKSRS). A median dose of 18 Gy (range, 10-24 Gy) was prescribed to the margin of each metastasis. Patients were followed with serial imaging. Patient electronic records were reviewed to determine disease-related factors and clinical outcomes after GKSRS. Local and distant brain failure rates, overall survival, and likelihood of neurologic death were determined based on imaging results. The Kaplan-Meier method was used to determine survival and local and distant brain control. Cox proportional hazard regression was performed to determine strength of association between disease-related factors and survival. Median survival time for the entire cohort was 5.9 months. Local control rates at 1 and 2 years were 57% and 34%, respectively. Distant brain failure rates at 1 and 2 years were 58% and 75%, respectively. Fifty-three percent of patients ultimately died of neurologic death. On multivariate analysis, patients with stable (hazard ratio [HR] = 2.89) or progressive (HR = 6.98) extracranial disease (ECD) had worse overall survival than patients without evidence of ECD (p = 0.00002). Concurrent chemotherapy improved local control (HR = 89; p = 0.006). GKSRS represents a feasible salvage option in patients with SCLC and brain metastases for whom previous WBI has failed. The status of patients' ECD is a dominant factor predictive of overall survival. Local control may be inferior to that seen with other cancer histological results, although the use of concurrent chemotherapy may help to improve this. Copyright © 2012 Elsevier Inc. All rights

  10. Gamma Knife Stereotactic Radiosurgery as Salvage Therapy After Failure of Whole-Brain Radiotherapy in Patients With Small-Cell Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Sunit [Department of Radiation Oncology, Wake Forest University, Winston-Salem, North Carolina (United States); Chan, Michael D., E-mail: mchan@wfubmc.edu [Department of Radiation Oncology, Wake Forest University, Winston-Salem, North Carolina (United States); Lovato, James F. [Division of Public Health Sciences, Wake Forest University, Winston-Salem, North Carolina (United States); Ellis, Thomas L.; Tatter, Stephen B. [Department of Neurosurgery, Wake Forest University, Winston-Salem, North Carolina (United States); Bourland, J. Daniel; Munley, Michael T.; Guzman, Allan F. de; Shaw, Edward G.; Urbanic, James J.; McMullen, Kevin P. [Department of Radiation Oncology, Wake Forest University, Winston-Salem, North Carolina (United States)

    2012-05-01

    Purpose: Radiosurgery has been successfully used in selected cases to avoid repeat whole-brain irradiation (WBI) in patients with multiple brain metastases of most solid tumor histological findings. Few data are available for the use of radiosurgery for small-cell lung cancer (SCLC). Methods and Materials: Between November 1999 and June 2009, 51 patients with SCLC and previous WBI and new brain metastases were treated with GammaKnife stereotactic radiosurgery (GKSRS). A median dose of 18 Gy (range, 10-24 Gy) was prescribed to the margin of each metastasis. Patients were followed with serial imaging. Patient electronic records were reviewed to determine disease-related factors and clinical outcomes after GKSRS. Local and distant brain failure rates, overall survival, and likelihood of neurologic death were determined based on imaging results. The Kaplan-Meier method was used to determine survival and local and distant brain control. Cox proportional hazard regression was performed to determine strength of association between disease-related factors and survival. Results: Median survival time for the entire cohort was 5.9 months. Local control rates at 1 and 2 years were 57% and 34%, respectively. Distant brain failure rates at 1 and 2 years were 58% and 75%, respectively. Fifty-three percent of patients ultimately died of neurologic death. On multivariate analysis, patients with stable (hazard ratio [HR] = 2.89) or progressive (HR = 6.98) extracranial disease (ECD) had worse overall survival than patients without evidence of ECD (p = 0.00002). Concurrent chemotherapy improved local control (HR = 89; p = 0.006). Conclusions: GKSRS represents a feasible salvage option in patients with SCLC and brain metastases for whom previous WBI has failed. The status of patients' ECD is a dominant factor predictive of overall survival. Local control may be inferior to that seen with other cancer histological results, although the use of concurrent chemotherapy may help to

  11. SNPs in the TGF-β signaling pathway are associated with increased risk of brain metastasis in patients with non-small-cell lung cancer.

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    Qianxia Li

    Full Text Available PURPOSE: Brain metastasis (BM from non-small cell lung cancer (NSCLC is relatively common, but identifying which patients will develop brain metastasis has been problematic. We hypothesized that genotype variants in the TGF-β signaling pathway could be a predictive biomarker of brain metastasis. PATIENTS AND METHODS: We genotyped 33 SNPs from 13 genes in the TGF-β signaling pathway and evaluated their associations with brain metastasis risk by using DNA from blood samples from 161 patients with NSCLC. Kaplan-Meier analysis was used to assess brain metastasis risk; Cox hazard analyses were used to evaluate the effects of various patient and disease characteristics on the risk of brain metastasis. RESULTS: The median age of the 116 men and 45 women in the study was 58 years; 62 (39% had stage IIIB or IV disease. Within 24 months after initial diagnosis of lung cancer, brain metastasis was found in 60 patients (37%. Of these 60 patients, 16 had presented with BM at diagnosis. Multivariate analysis showed the GG genotype of SMAD6: rs12913975 and TT genotype of INHBC: rs4760259 to be associated with a significantly higher risk of brain metastasis at 24 months follow-up (hazard ratio [HR] 2.540, 95% confidence interval [CI] 1.204-5.359, P = 0.014; and HR 1.885, 95% CI 1.086-3.273, P = 0.024, compared with the GA or CT/CC genotypes, respectively. When we analyzed combined subgroups, these rates showed higher for those having both the GG genotype of SMAD6: rs12913975 and the TT genotype of INHBC: rs4760259 (HR 2.353, 95% CI 1.390-3.985, P = 0.001. CONCLUSIONS: We found the GG genotype of SMAD6: rs12913975 and TT genotype of INHBC: rs4760259 to be associated with risk of brain metastasis in patients with NSCLC. This finding, if confirmed, can help to identify patients at high risk of brain metastasis.

  12. Trust Propagation in Small Worlds

    DEFF Research Database (Denmark)

    Gray, Elizabeth; Seigneur, Jean-Marc; Chen, Yong

    2003-01-01

    The possibility of a massive, networked infrastructure of diverse entities partaking in collaborative applications with each other increases more and more with the proliferation of mobile devices and the development of ad hoc networking technologies. In this context, traditional security measures...

  13. MRI-Only Based Radiotherapy Treatment Planning for the Rat Brain on a Small Animal Radiation Research Platform (SARRP.

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    Shandra Gutierrez

    Full Text Available Computed tomography (CT is the standard imaging modality in radiation therapy treatment planning (RTP. However, magnetic resonance (MR imaging provides superior soft tissue contrast, increasing the precision of target volume selection. We present MR-only based RTP for a rat brain on a small animal radiation research platform (SARRP using probabilistic voxel classification with multiple MR sequences. Six rat heads were imaged, each with one CT and five MR sequences. The MR sequences were: T1-weighted, T2-weighted, zero-echo time (ZTE, and two ultra-short echo time sequences with 20 μs (UTE1 and 2 ms (UTE2 echo times. CT data were manually segmented into air, soft tissue, and bone to obtain the RTP reference. Bias field corrected MR images were automatically segmented into the same tissue classes using a fuzzy c-means segmentation algorithm with multiple images as input. Similarities between segmented CT and automatic segmented MR (ASMR images were evaluated using Dice coefficient. Three ASMR images with high similarity index were used for further RTP. Three beam arrangements were investigated. Dose distributions were compared by analysing dose volume histograms. The highest Dice coefficients were obtained for the ZTE-UTE2 combination and for the T1-UTE1-T2 combination when ZTE was unavailable. Both combinations, along with UTE1-UTE2, often used to generate ASMR images, were used for further RTP. Using 1 beam, MR based RTP underestimated the dose to be delivered to the target (range: 1.4%-7.6%. When more complex beam configurations were used, the calculated dose using the ZTE-UTE2 combination was the most accurate, with 0.7% deviation from CT, compared to 0.8% for T1-UTE1-T2 and 1.7% for UTE1-UTE2. The presented MR-only based workflow for RTP on a SARRP enables both accurate organ delineation and dose calculations using multiple MR sequences. This method can be useful in longitudinal studies where CT's cumulative radiation dose might contribute

  14. MRI-Only Based Radiotherapy Treatment Planning for the Rat Brain on a Small Animal Radiation Research Platform (SARRP).

    Science.gov (United States)

    Gutierrez, Shandra; Descamps, Benedicte; Vanhove, Christian

    2015-01-01

    Computed tomography (CT) is the standard imaging modality in radiation therapy treatment planning (RTP). However, magnetic resonance (MR) imaging provides superior soft tissue contrast, increasing the precision of target volume selection. We present MR-only based RTP for a rat brain on a small animal radiation research platform (SARRP) using probabilistic voxel classification with multiple MR sequences. Six rat heads were imaged, each with one CT and five MR sequences. The MR sequences were: T1-weighted, T2-weighted, zero-echo time (ZTE), and two ultra-short echo time sequences with 20 μs (UTE1) and 2 ms (UTE2) echo times. CT data were manually segmented into air, soft tissue, and bone to obtain the RTP reference. Bias field corrected MR images were automatically segmented into the same tissue classes using a fuzzy c-means segmentation algorithm with multiple images as input. Similarities between segmented CT and automatic segmented MR (ASMR) images were evaluated using Dice coefficient. Three ASMR images with high similarity index were used for further RTP. Three beam arrangements were investigated. Dose distributions were compared by analysing dose volume histograms. The highest Dice coefficients were obtained for the ZTE-UTE2 combination and for the T1-UTE1-T2 combination when ZTE was unavailable. Both combinations, along with UTE1-UTE2, often used to generate ASMR images, were used for further RTP. Using 1 beam, MR based RTP underestimated the dose to be delivered to the target (range: 1.4%-7.6%). When more complex beam configurations were used, the calculated dose using the ZTE-UTE2 combination was the most accurate, with 0.7% deviation from CT, compared to 0.8% for T1-UTE1-T2 and 1.7% for UTE1-UTE2. The presented MR-only based workflow for RTP on a SARRP enables both accurate organ delineation and dose calculations using multiple MR sequences. This method can be useful in longitudinal studies where CT's cumulative radiation dose might contribute to the total

  15. Correlation between EGFR mutation status and the incidence of brain metastases in patients with non-small cell lung cancer.

    Science.gov (United States)

    Li, Lina; Luo, Shuimei; Lin, Heng; Yang, Haitao; Chen, Huijuan; Liao, Ziyuan; Lin, Wanzun; Zheng, Weili; Xie, Xianhe

    2017-08-01

    Lung cancer is the leading cause of cancer-related death worldwide. Numerous studies have been performed to investigate the correlation between epidermal growth factor receptor (EGFR) mutation status and the incidence of brain metastases (BMs) in patients with non-small cell lung cancer (NSCLC), however, the outcomes were inconsistent. Thus, we performed this study to establish the role of EGFR mutation status in BMs. Electronic databases PubMed, Embase, Cochrane Library, CBM, WanFang, CNKI were searched to identify relevant trials. The primary endpoint was the incidence of BMs in EGFR mutations or wild type NSCLC and the secondary endpoint was overall survival calculated from the BMs emerging (BMOS). Twenty-two studies incorporating 8,152 participants were eligible. EGFR mutations group possessed a significantly higher risk of BMs (OR =1.99; 95% CI, 1.59-2.48; P=0.000) than EGFR wild type group. In the stratified analysis, compared with EGFR wild type group, EGFR mutations group had a significant higher incidence (OR =2.01; 95% CI, 1.56-2.59; P=0.000) of subsequent BMs while only a trend of increasing the incidence of initial BMs (OR =1.38; 95% CI, 0.98-1.94; P=0.066). Moreover, exon 19 deletion had a trend of increasing the incidence of BMs than exon 21 mutation (OR =1.44; 95% CI, 0.77-2.68; P=0.252). Compared with EGFR wild type group, EGFR mutations group possessed a prolonged overall BMOS (HR =0.68; 95% CI, 0.47-0.98; P=0.038) and a longer BMOS in initial BMs (HR =0.50; 95% CI, 0.31-0.80; P=0.004) but no significant difference in NSCLC with subsequent BMs (HR =0.95; 95% CI, 0.42-2.15; P=0.901). Patients with EGFR mutations were more susceptible to develop into BMs than those with EGFR wild type, especially during the course of disease.

  16. Functioning and Disability Analysis of Patients with Traumatic Brain Injury and Spinal Cord Injury by Using the World Health Organization Disability Assessment Schedule 2.0

    Directory of Open Access Journals (Sweden)

    Chia-Ying Kuo

    2015-04-01

    Full Text Available The purpose of this study is to compare traumatic brain injuries (TBI and spinal cord injuries (SCI patients’ function and disability by using the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0; and to clarify the factors that contribute to disability. We analyzed data available between September 2012 and August 2013 from Taiwan’s national disability registry which is based on the International Classification of Functioning, Disability, and Health (ICF framework. Of the 2664 cases selected for the study, 1316 pertained to TBI and 1348 to SCI. A larger percentage of patients with TBI compared with those with SCI exhibited poor cognition, self-care, relationships, life activities, and participation in society (all p < 0.001. Age, sex, injury type, socioeconomic status, place of residence, and severity of impairment were determined as factors that independently contribute to disability (all p < 0.05. The WHODAS 2.0 is a generic assessment instrument which is appropriate for assessing the complex and multifaceted disability associated with TBI and SCI. Further studies are needed to validate the WHODAS 2.0 for TBI and SCI from a multidisciplinary perspective.

  17. Spatial modeling of personalized exposure dynamics: the case of pesticide use in small-scale agricultural production landscapes of the developing world

    Directory of Open Access Journals (Sweden)

    Binder Claudia R

    2009-03-01

    Full Text Available Abstract Background Pesticide poisoning is a global health issue with the largest impacts in the developing countries where residential and small-scale agricultural areas are often integrated and pesticides sprayed manually. To reduce health risks from pesticide exposure approaches for personalized exposure assessment (PEA are needed. We present a conceptual framework to develop a spatial individual-based model (IBM prototype for assessing potential exposure of farm-workers conducting small-scale agricultural production, which accounts for a considerable portion of global food crop production. Our approach accounts for dynamics in the contaminant distributions in the environment, as well as patterns of movement and activities performed on an individual level under different safety scenarios. We demonstrate a first prototype using data from a study area in a rural part of Colombia, South America. Results Different safety scenarios of PEA were run by including weighting schemes for activities performed under different safety conditions. We examined the sensitivity of individual exposure estimates to varying patterns of pesticide application and varying individual patterns of movement. This resulted in a considerable variation in estimates of magnitude, frequency and duration of exposure over the model runs for each individual as well as between individuals. These findings indicate the influence of patterns of pesticide application, individual spatial patterns of movement as well as safety conditions on personalized exposure in the agricultural production landscape that is the focus of our research. Conclusion This approach represents a conceptual framework for developing individual based models to carry out PEA in small-scale agricultural settings in the developing world based on individual patterns of movement, safety conditions, and dynamic contaminant distributions. The results of our analysis indicate our prototype model is sufficiently

  18. Energy compensation in the real world: good compensation for small portions of chocolate and biscuits over short time periods in complicit consumers using commercially available foods.

    Science.gov (United States)

    Appleton, Katherine M; McKeown, Pascal P; Woodside, Jayne V

    2015-02-01

    While investigations using covert food manipulations tend to suggest that individuals are poor at adjusting for previous energy intake, in the real world adults rarely consume foods of which they are ill-informed. This study investigated the impact in fully complicit consumers of consuming commercially available dark chocolate, milk chocolate, sweet biscuits and fruit bars on subsequent appetite. Using a repeated measures design, participants received four small portions (4 × 10-11 g) of either dark chocolate, milk chocolate, sweet biscuits, fruit bars or no food throughout five separate study days (counterbalanced in order), and test meal intake, hunger, liking and acceptability were measured. Participants consumed significantly less at lunch following dark chocolate, milk chocolate and sweet biscuits compared to no food (smallest t(19) = 2.47, p = 0.02), demonstrating very good energy compensation (269-334%). No effects were found for fruit bars (t(19) = 1.76, p = 0.09), in evening meal intakes (F(4,72) = 0.62, p = 0.65) or in total intake (lunch + evening meal + food portions) (F(4,72) = 0.40, p = 0.69). No differences between conditions were found in measures of hunger (largest F(4,76) = 1.26, p = 0.29), but fruit bars were significantly less familiar than all other foods (smallest t(19) = 3.14, p = 0.01). These findings demonstrate good compensation over the short term for small portions of familiar foods in complicit consumers. Findings are most plausibly explained as a result of participant awareness and cognitions, although the nature of these cognitions cannot be discerned from this study. These findings however, also suggest that covert manipulations may have limited transfer to real world scenarios. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Solitary brain metastasis of an occult and stable small-cell lung cancer in a schizophrenic patient: a 3-year control.

    Science.gov (United States)

    Jesien-Lewandowicz, Emilia; Spych, Michal; Fijuth, Jacek; Kordek, Radzislaw

    2010-08-01

    Small-cell lung cancer is a highly aggressive carcinoma, with poorer prognosis in patients with brain metastases. We present the case of a 49-year-old woman diagnosed with a cerebellar tumour which, following surgery, was revealed to be a metastatic small-cell lung carcinoma. Subsequent CT and PET scanning showed a small, isolated 8 mm nodule in the upper lobe of the right lung. The patient was suffering from schizophrenia and has been treated with clozapine for 17 years. Because of the unusual presentation, there was no therapy given for the primary tumour at the time, and systemic therapy or surgery was discussed. However, 18 months later, the nodule was slightly larger (14 mm), and surgery was performed. On pathology examination, the tumour was presented as a typical small-cell carcinoma. Standard chest irradiation with systemic chemotherapy was given. At the time of writing, 39 months after diagnosis of metastatic small-cell carcinoma, the patient is disease free. However, this case is unusual in that a long-term observation of a small stable primary tumour in the lung took place without any therapy being given. This case strongly supports the thesis that small-cell lung cancer may comprise a heterogeneous group of tumours with different biological properties. The proapoptotic effect of clozapine may be also taken into account.

  20. Analysis of Small Ischemic Lesions in the Examinees of a Brain Dock and Neurological Examination of Animals Subjected to Cortical or Basal Ganglia Photothrombotic Infarction.

    Science.gov (United States)

    Kuroiwa, Toshihiko; Tabata, Hitoshi; Xi, Guohua; Hua, Ya; Schallert, Timothy; Keep, Richard F

    2016-01-01

    We analyzed cases of small brain ischemic lesions found in examinees of a brain dock (neurological health screening center). Small cerebral infarction was found in 17 % of the examinees (733 cases). White matter lesions were found in 24 %. Infarctions were located in the cortex or subcortical white matter in 31 % and in the basal ganglia in 44 % of cases. Infratentorial infarction was found in 1.6 %. We have developed an animal model of small infarction in the cortex or basal ganglia induced by photothrombosis in rodents. Sprague-Dawley rats or Mongolian gerbils were anesthetized and photothrombotic infarction was induced in the left caudate nucleus or parietal cortex by light exposure via an optic fiber and intravenous Rose Bengal dye injection. Histological examination revealed development of a small spherical infarction surrounding the tip of the optic fiber. The lesion turned to a cyst by 6 weeks after lesioning. Neurological deficits were found in animals both with cortical and caudate infarction. Behavioral changes in an open field test differed with the lesion site. Neurological deficits were sustained longer in animals with larger infarctions. Thus, photothrombotic infarction is useful for analyzing location-dependent and size-dependent neurological and neuropathological changes after cerebral infarction.