Trade Integration and Trade Imbalances in the European Union: A Network Perspective

PubMed Central

Krings, Gautier M.; Carpantier, Jean-François; Delvenne, Jean-Charles

2014-01-01

We study the ever more integrated and ever more unbalanced trade relationships between European countries. To better capture the complexity of economic networks, we propose two global measures that assess the trade integration and the trade imbalances of the European countries. These measures are the network (or indirect) counterparts to traditional (or direct) measures such as the trade-to-GDP (Gross Domestic Product) and trade deficit-to-GDP ratios. Our indirect tools account for the European inter-country trade structure and follow (i) a decomposition of the global trade flow into elementary flows that highlight the long-range dependencies between exporting and importing economies and (ii) the commute-time distance for trade integration, which measures the impact of a perturbation in the economy of a country on another country, possibly through intermediate partners by domino effect. Our application addresses the impact of the launch of the Euro. We find that the indirect imbalance measures better identify the countries ultimately bearing deficits and surpluses, by neutralizing the impact of trade transit countries, such as the Netherlands. Among others, we find that ultimate surpluses of Germany are quite concentrated in only three partners. We also show that for some countries, the direct and indirect measures of trade integration diverge, thereby revealing that these countries (e.g. Greece and Portugal) trade to a smaller extent with countries considered as central in the European Union network. PMID:24465381

Trade integration and trade imbalances in the European Union: a network perspective.

PubMed

Krings, Gautier M; Carpantier, Jean-François; Delvenne, Jean-Charles

2014-01-01

We study the ever more integrated and ever more unbalanced trade relationships between European countries. To better capture the complexity of economic networks, we propose two global measures that assess the trade integration and the trade imbalances of the European countries. These measures are the network (or indirect) counterparts to traditional (or direct) measures such as the trade-to-GDP (Gross Domestic Product) and trade deficit-to-GDP ratios. Our indirect tools account for the European inter-country trade structure and follow (i) a decomposition of the global trade flow into elementary flows that highlight the long-range dependencies between exporting and importing economies and (ii) the commute-time distance for trade integration, which measures the impact of a perturbation in the economy of a country on another country, possibly through intermediate partners by domino effect. Our application addresses the impact of the launch of the Euro. We find that the indirect imbalance measures better identify the countries ultimately bearing deficits and surpluses, by neutralizing the impact of trade transit countries, such as the Netherlands. Among others, we find that ultimate surpluses of Germany are quite concentrated in only three partners. We also show that for some countries, the direct and indirect measures of trade integration diverge, thereby revealing that these countries (e.g. Greece and Portugal) trade to a smaller extent with countries considered as central in the European Union network.

INDIRECT INTELLIGENT SLIDING MODE CONTROL OF A SHAPE MEMORY ALLOY ACTUATED FLEXIBLE BEAM USING HYSTERETIC RECURRENT NEURAL NETWORKS.

PubMed

Hannen, Jennifer C; Crews, John H; Buckner, Gregory D

2012-08-01

This paper introduces an indirect intelligent sliding mode controller (IISMC) for shape memory alloy (SMA) actuators, specifically a flexible beam deflected by a single offset SMA tendon. The controller manipulates applied voltage, which alters SMA tendon temperature to track reference bending angles. A hysteretic recurrent neural network (HRNN) captures the nonlinear, hysteretic relationship between SMA temperature and bending angle. The variable structure control strategy provides robustness to model uncertainties and parameter variations, while effectively compensating for system nonlinearities, achieving superior tracking compared to an optimized PI controller.

Methamphetamine Use among Homeless Former Foster Youth: The Mediating Role of Social Networks

PubMed Central

Yoshioka-Maxwell, Amanda; Rice, Eric; Rhoades, Harmony; Winetrobe, Hailey

2015-01-01

Objectives Social network analysis can provide added causal insight into otherwise confusing epidemiologic findings in public health research. Although foster care and homelessness are risk factors for methamphetamine use, current research has failed to explicate why homeless youth with foster care experience engage in methamphetamine use at higher rates than other homeless young adults. This study examined the mediating effect of network engagement and time spent homeless on the relationship between foster care experience and recent methamphetamine use among homeless youth in Los Angeles. Methods Egocentric network data from a cross-sectional community-based sample (n = 652) of homeless youth aged 13–25 were collected from drop-in centers in Los Angeles. Questions addressed foster care experience, time spent homeless, methamphetamine use, and perceived drug use in social networks. Path analysis was performed in SAS to examine mediation. Results Controlling for all other variables, results of path analysis regarding recent methamphetamine use indicated a direct effect between foster care experience and recent methamphetamine use (B = .269, t = 2.73, p < .01). However, this direct effect became statistically nonsignificant when time spent homeless and network methamphetamine use were added to the model, and indirect paths from time spent homeless and network methamphetamine use became statistically significant. Conclusions Foster care experience influenced recent methamphetamine use indirectly through time spent homeless and methamphetamine use by network members. Efforts to reduce methamphetamine use should focus on securing stable housing and addressing network interactions among homeless former foster youth. PMID:26146647

Lateralized direct and indirect semantic priming effects in subjects with paranormal experiences and beliefs.

PubMed

Pizzagalli, D; Lehmann, D; Brugger, P

2001-01-01

The present investigation tested the hypothesis that, as an aspect of schizotypal thinking, the formation of paranormal beliefs was related to spreading activation characteristics within semantic networks. From a larger student population (n = 117) prescreened for paranormal belief, 12 strong believers and 12 strong disbelievers (all women) were invited for a lateralized semantic priming task with directly and indirectly related prime-target pairs. Believers showed stronger indirect (but not direct) semantic priming effects than disbelievers after left (but not right) visual field stimulation, indicating faster appreciation of distant semantic relations specifically by the right hemisphere, reportedly specialized in coarse rather than focused semantic processing. These results are discussed in the light of recent findings in schizophrenic patients with thought disorders. They suggest that a disinhibition with semantic networks may underlie the formation of paranormal belief. The potential usefulness of work with healthy subjects for neuropsychiatric research is stressed. Copyright 2001 S. Karger AG, Basel

Analysis of a summary network of co-infection in humans reveals that parasites interact most via shared resources

PubMed Central

Griffiths, Emily C.; Pedersen, Amy B.; Fenton, Andy; Petchey, Owen L.

2014-01-01

Simultaneous infection by multiple parasite species (viruses, bacteria, helminths, protozoa or fungi) is commonplace. Most reports show co-infected humans to have worse health than those with single infections. However, we have little understanding of how co-infecting parasites interact within human hosts. We used data from over 300 published studies to construct a network that offers the first broad indications of how groups of co-infecting parasites tend to interact. The network had three levels comprising parasites, the resources they consume and the immune responses they elicit, connected by potential, observed and experimentally proved links. Pairs of parasite species had most potential to interact indirectly through shared resources, rather than through immune responses or other parasites. In addition, the network comprised 10 tightly knit groups, eight of which were associated with particular body parts, and seven of which were dominated by parasite–resource links. Reported co-infection in humans is therefore structured by physical location within the body, with bottom-up, resource-mediated processes most often influencing how, where and which co-infecting parasites interact. The many indirect interactions show how treating an infection could affect other infections in co-infected patients, but the compartmentalized structure of the network will limit how far these indirect effects are likely to spread. PMID:24619434

Analysis of a summary network of co-infection in humans reveals that parasites interact most via shared resources.

PubMed

Griffiths, Emily C; Pedersen, Amy B; Fenton, Andy; Petchey, Owen L

2014-05-07

Simultaneous infection by multiple parasite species (viruses, bacteria, helminths, protozoa or fungi) is commonplace. Most reports show co-infected humans to have worse health than those with single infections. However, we have little understanding of how co-infecting parasites interact within human hosts. We used data from over 300 published studies to construct a network that offers the first broad indications of how groups of co-infecting parasites tend to interact. The network had three levels comprising parasites, the resources they consume and the immune responses they elicit, connected by potential, observed and experimentally proved links. Pairs of parasite species had most potential to interact indirectly through shared resources, rather than through immune responses or other parasites. In addition, the network comprised 10 tightly knit groups, eight of which were associated with particular body parts, and seven of which were dominated by parasite-resource links. Reported co-infection in humans is therefore structured by physical location within the body, with bottom-up, resource-mediated processes most often influencing how, where and which co-infecting parasites interact. The many indirect interactions show how treating an infection could affect other infections in co-infected patients, but the compartmentalized structure of the network will limit how far these indirect effects are likely to spread.

Gender Variations in the Effects of Number of Organizational Memberships, Number of Social Networking Sites, and Grade-Point Average on Global Social Responsibility in Filipino University Students

PubMed Central

Lee, Romeo B.; Baring, Rito V.; Sta. Maria, Madelene A.

2016-01-01

The study seeks to estimate gender variations in the direct effects of (a) number of organizational memberships, (b) number of social networking sites (SNS), and (c) grade-point average (GPA) on global social responsibility (GSR); and in the indirect effects of (a) and of (b) through (c) on GSR. Cross-sectional survey data were drawn from questionnaire interviews involving 3,173 Filipino university students. Based on a path model, the three factors were tested to determine their inter-relationships and their relationships with GSR. The direct and total effects of the exogenous factors on the dependent variable are statistically significantly robust. The indirect effects of organizational memberships on GSR through GPA are also statistically significant, but the indirect effects of SNS on GSR through GPA are marginal. Men and women significantly differ only in terms of the total effects of their organizational memberships on GSR. The lack of broad gender variations in the effects of SNS, organizational memberships and GPA on GSR may be linked to the relatively homogenous characteristics and experiences of the university students interviewed. There is a need for more path models to better understand the predictors of GSR in local students. PMID:27247700

Gender Variations in the Effects of Number of Organizational Memberships, Number of Social Networking Sites, and Grade-Point Average on Global Social Responsibility in Filipino University Students.

PubMed

Lee, Romeo B; Baring, Rito V; Sta Maria, Madelene A

2016-02-01

The study seeks to estimate gender variations in the direct effects of (a) number of organizational memberships, (b) number of social networking sites (SNS), and (c) grade-point average (GPA) on global social responsibility (GSR); and in the indirect effects of (a) and of (b) through (c) on GSR. Cross-sectional survey data were drawn from questionnaire interviews involving 3,173 Filipino university students. Based on a path model, the three factors were tested to determine their inter-relationships and their relationships with GSR. The direct and total effects of the exogenous factors on the dependent variable are statistically significantly robust. The indirect effects of organizational memberships on GSR through GPA are also statistically significant, but the indirect effects of SNS on GSR through GPA are marginal. Men and women significantly differ only in terms of the total effects of their organizational memberships on GSR. The lack of broad gender variations in the effects of SNS, organizational memberships and GPA on GSR may be linked to the relatively homogenous characteristics and experiences of the university students interviewed. There is a need for more path models to better understand the predictors of GSR in local students.

Microbiome Networks: A Systems Framework for Identifying Candidate Microbial Assemblages for Disease Management.

PubMed

Poudel, R; Jumpponen, A; Schlatter, D C; Paulitz, T C; Gardener, B B McSpadden; Kinkel, L L; Garrett, K A

2016-10-01

Network models of soil and plant microbiomes provide new opportunities for enhancing disease management, but also challenges for interpretation. We present a framework for interpreting microbiome networks, illustrating how observed network structures can be used to generate testable hypotheses about candidate microbes affecting plant health. The framework includes four types of network analyses. "General network analysis" identifies candidate taxa for maintaining an existing microbial community. "Host-focused analysis" includes a node representing a plant response such as yield, identifying taxa with direct or indirect associations with that node. "Pathogen-focused analysis" identifies taxa with direct or indirect associations with taxa known a priori as pathogens. "Disease-focused analysis" identifies taxa associated with disease. Positive direct or indirect associations with desirable outcomes, or negative associations with undesirable outcomes, indicate candidate taxa. Network analysis provides characterization not only of taxa with direct associations with important outcomes such as disease suppression, biofertilization, or expression of plant host resistance, but also taxa with indirect associations via their association with other key taxa. We illustrate the interpretation of network structure with analyses of microbiomes in the oak phyllosphere, and in wheat rhizosphere and bulk soil associated with the presence or absence of infection by Rhizoctonia solani.

Analysis of the error of the developed method of determination the active conductivity reducing the insulation level between one phase of the network and ground, and insulation parameters in a non-symmetric network with isolated neutral with voltage above 1000 V

NASA Astrophysics Data System (ADS)

Utegulov, B. B.

2018-02-01

In the work the study of the developed method was carried out for reliability by analyzing the error in indirect determination of the insulation parameters in an asymmetric network with an isolated neutral voltage above 1000 V. The conducted studies of the random relative mean square errors show that the accuracy of indirect measurements in the developed method can be effectively regulated not only by selecting a capacitive additional conductivity, which are connected between phases of the electrical network and the ground, but also by the selection of measuring instruments according to the accuracy class. When choosing meters with accuracy class of 0.5 with the correct selection of capacitive additional conductivity that are connected between the phases of the electrical network and the ground, the errors in measuring the insulation parameters will not exceed 10%.

Modelling of piezoelectric actuator dynamics for active structural control

NASA Technical Reports Server (NTRS)

Hagood, Nesbitt W.; Chung, Walter H.; Von Flotow, Andreas

1990-01-01

The paper models the effects of dynamic coupling between a structure and an electrical network through the piezoelectric effect. The coupled equations of motion of an arbitrary elastic structure with piezoelectric elements and passive electronics are derived. State space models are developed for three important cases: direct voltage driven electrodes, direct charge driven electrodes, and an indirect drive case where the piezoelectric electrodes are connected to an arbitrary electrical circuit with embedded voltage and current sources. The equations are applied to the case of a cantilevered beam with surface mounted piezoceramics and indirect voltage and current drive. The theoretical derivations are validated experimentally on an actively controlled cantilevered beam test article with indirect voltage drive.

Friends of friends: are indirect connections in social networks important to animal behaviour?

PubMed

Brent, Lauren J N

2015-05-01

Friend of a friend relationships, or the indirect connections between people, influence our health, well-being, financial success and reproductive output. As with humans, social behaviours in other animals often occur within a broad interconnected network of social ties. Yet studies of animal social behaviour tend to focus on associations between pairs of individuals. With the increase in popularity of social network analysis, researchers have started to look beyond the dyad to examine the role of indirect connections in animal societies. Here, I provide an overview of the new knowledge that has been uncovered by these studies. I focus on research that has addressed both the causes of social behaviours, i.e. the cognitive and genetic basis of indirect connections, as well as their consequences, i.e. the impact of indirect connections on social cohesion, information transfer, cultural practices and fitness. From these studies, it is apparent that indirect connections play an important role in animal behaviour, although future research is needed to clarify their contribution.

Friends of friends: are indirect connections in social networks important to animal behaviour?

PubMed Central

Brent, Lauren J. N.

2015-01-01

Friend of a friend relationships, or the indirect connections between people, influence our health, well-being, financial success and reproductive output. As with humans, social behaviours in other animals often occur within a broad interconnected network of social ties. Yet studies of animal social behaviour tend to focus on associations between pairs of individuals. With the increase in popularity of social network analysis, researchers have started to look beyond the dyad to examine the role of indirect connections in animal societies. Here, I provide an overview of the new knowledge that has been uncovered by these studies. I focus on research that has addressed both the causes of social behaviours, i.e. the cognitive and genetic basis of indirect connections, as well as their consequences, i.e. the impact of indirect connections on social cohesion, information transfer, cultural practices and fitness. From these studies, it is apparent that indirect connections play an important role in animal behaviour, although future research is needed to clarify their contribution. PMID:25937639

Nonzero-Sum Relationships in Mitigating Urban Carbon Emissions: A Dynamic Network Simulation.

PubMed

Chen, Shaoqing; Chen, Bin; Su, Meirong

2015-10-06

The "stove-pipe" way of thinking has been mostly used in mitigating carbon emissions and managing socioeconomics because of its convenience of implementation. However, systems-oriented approaches become imperative in pursuit of an efficient regulation of carbon emissions from systems as complicated as urban systems. The aim of this paper is to establish a dynamic network approach that is capable of assessing the effectiveness of carbon emissions mitigation in a more holistic way. A carbon metabolic network is constructed by modeling the carbon flows between economic sectors and environment. With the network shocked by interventions to the sectoral carbon flows, indirect emissions from the city are accounted for under certain carbon mitigation strategies. The nonzero-sum relationships between sectors and environmental components are identified based on utility analysis, which synthesize the nature of direct and indirect network interactions. The results of the case study of Beijing suggest that the stove-pipe mitigation strategies targeted the economic sectors might be not as efficient as they were expected. A direct cutting in material or energy import to the sectors may result in a rebound in indirect emissions and thus fails to achieve the carbon mitigation goal of the city as a whole. A promising way of foreseeing the dynamic mechanism of emissions is to analyze the nonzero-sum relationships between important urban components. Thinking cities as systems of interactions, the network approach is potentially a strong tool for appraising and filtering mitigation strategies of carbon emissions.

Indirect adaptive fuzzy wavelet neural network with self- recurrent consequent part for AC servo system.

PubMed

Hou, Runmin; Wang, Li; Gao, Qiang; Hou, Yuanglong; Wang, Chao

2017-09-01

This paper proposes a novel indirect adaptive fuzzy wavelet neural network (IAFWNN) to control the nonlinearity, wide variations in loads, time-variation and uncertain disturbance of the ac servo system. In the proposed approach, the self-recurrent wavelet neural network (SRWNN) is employed to construct an adaptive self-recurrent consequent part for each fuzzy rule of TSK fuzzy model. For the IAFWNN controller, the online learning algorithm is based on back propagation (BP) algorithm. Moreover, an improved particle swarm optimization (IPSO) is used to adapt the learning rate. The aid of an adaptive SRWNN identifier offers the real-time gradient information to the adaptive fuzzy wavelet neural controller to overcome the impact of parameter variations, load disturbances and other uncertainties effectively, and has a good dynamic. The asymptotical stability of the system is guaranteed by using the Lyapunov method. The result of the simulation and the prototype test prove that the proposed are effective and suitable. Copyright © 2017. Published by Elsevier Ltd.

A Structural Model of Depression Based on Interpersonal Relationships: The Mediating Role of Coping Strategies and Loneliness.

PubMed

Majd Ara, Elahe; Talepasand, Siavash; Rezaei, Ali Mohammad

2017-06-01

The present study was conducted with the aim of examining the structural model of interpersonal relationships and depression using coping strategies and loneliness as mediators. Using multistage random sampling, 301 high-school students were selected from Minudasht city, Iran. The participants were aksed to complete the Network of Relationships Inventory (NRI); the Ways of Coping Questionnaire (Lazarus and Folkman); the Children's Loneliness Scale (CLS); and the Depression, Anxiety, and Stress Scale (DASS-21). Structural equation modeling was used to examine the pattern of direct and indirect effects. Findings of the present study show that the data are well fitted to the model. The indirect effect of the positive quality of relationships was significant on depression through loneliness. Moreover, the indirect effects of the negative quality of relationships on depression through loneliness and through emotion-focused coping strategies were statistically significant. Although the effect of loneliness and emotion-focused coping strategies on depression was significant, problem-focused coping strategies did not have a significant effect on depression. Additionally, the findings suggested that the indirect effect through loneliness on depression was stronger compared with the indirect effect through emotion-focused coping strategies. The positive or negative quality of interpersonal relationships, loneliness, and emotion-focused coping strategy can significantly predict depression.

Biological effects of direct and indirect manipulation of the fascial system. Narrative review.

PubMed

Parravicini, Giovanni; Bergna, Andrea

2017-04-01

Osteopathic Manipulative Treatment (OMT) is effective in improving function, movement and restoring pain conditions. Despite clinical results, the mechanisms of how OMT achieves its' effects remain unclear. The fascial system is described as a tensional network that envelops the human body. Direct or indirect manipulations of the fascial system are a distinctive part of OMT. This review describes the biological effects of direct and indirect manipulation of the fascial system. Literature search was performed in February 2016 in the electronic databases: Cochrane, Medline, Scopus, Ostmed, Pedro and authors' publications relative to Fascia Research Congress Website. Manipulation of the fascial system seems to interfere with some cellular processes providing various pro-inflammatory and anti-inflammatory cells and molecules. Despite growing research in the osteopathic field, biological effects of direct or indirect manipulation of the fascial system are not conclusive. To elevate manual medicine as a primary intervention in clinical settings, it's necessary to clarify how OMT modalities work in order to underpin their clinical efficacies. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inconsistency between direct and indirect comparisons of competing interventions: meta-epidemiological study.

PubMed

Song, Fujian; Xiong, Tengbin; Parekh-Bhurke, Sheetal; Loke, Yoon K; Sutton, Alex J; Eastwood, Alison J; Holland, Richard; Chen, Yen-Fu; Glenny, Anne-Marie; Deeks, Jonathan J; Altman, Doug G

2011-08-16

To investigate the agreement between direct and indirect comparisons of competing healthcare interventions. Meta-epidemiological study based on sample of meta-analyses of randomised controlled trials. Data sources Cochrane Database of Systematic Reviews and PubMed. Inclusion criteria Systematic reviews that provided sufficient data for both direct comparison and independent indirect comparisons of two interventions on the basis of a common comparator and in which the odds ratio could be used as the outcome statistic. Inconsistency measured by the difference in the log odds ratio between the direct and indirect methods. The study included 112 independent trial networks (including 1552 trials with 478,775 patients in total) that allowed both direct and indirect comparison of two interventions. Indirect comparison had already been explicitly done in only 13 of the 85 Cochrane reviews included. The inconsistency between the direct and indirect comparison was statistically significant in 16 cases (14%, 95% confidence interval 9% to 22%). The statistically significant inconsistency was associated with fewer trials, subjectively assessed outcomes, and statistically significant effects of treatment in either direct or indirect comparisons. Owing to considerable inconsistency, many (14/39) of the statistically significant effects by direct comparison became non-significant when the direct and indirect estimates were combined. Significant inconsistency between direct and indirect comparisons may be more prevalent than previously observed. Direct and indirect estimates should be combined in mixed treatment comparisons only after adequate assessment of the consistency of the evidence.

Inconsistency between direct and indirect comparisons of competing interventions: meta-epidemiological study

PubMed Central

Xiong, Tengbin; Parekh-Bhurke, Sheetal; Loke, Yoon K; Sutton, Alex J; Eastwood, Alison J; Holland, Richard; Chen, Yen-Fu; Glenny, Anne-Marie; Deeks, Jonathan J; Altman, Doug G

2011-01-01

Objective To investigate the agreement between direct and indirect comparisons of competing healthcare interventions. Design Meta-epidemiological study based on sample of meta-analyses of randomised controlled trials. Data sources Cochrane Database of Systematic Reviews and PubMed. Inclusion criteria Systematic reviews that provided sufficient data for both direct comparison and independent indirect comparisons of two interventions on the basis of a common comparator and in which the odds ratio could be used as the outcome statistic. Main outcome measure Inconsistency measured by the difference in the log odds ratio between the direct and indirect methods. Results The study included 112 independent trial networks (including 1552 trials with 478 775 patients in total) that allowed both direct and indirect comparison of two interventions. Indirect comparison had already been explicitly done in only 13 of the 85 Cochrane reviews included. The inconsistency between the direct and indirect comparison was statistically significant in 16 cases (14%, 95% confidence interval 9% to 22%). The statistically significant inconsistency was associated with fewer trials, subjectively assessed outcomes, and statistically significant effects of treatment in either direct or indirect comparisons. Owing to considerable inconsistency, many (14/39) of the statistically significant effects by direct comparison became non-significant when the direct and indirect estimates were combined. Conclusions Significant inconsistency between direct and indirect comparisons may be more prevalent than previously observed. Direct and indirect estimates should be combined in mixed treatment comparisons only after adequate assessment of the consistency of the evidence. PMID:21846695

A network analysis of indirect carbon emission flows among different industries in China.

PubMed

Du, Qiang; Xu, Yadan; Wu, Min; Sun, Qiang; Bai, Libiao; Yu, Ming

2018-06-17

Indirect carbon emissions account for a large ratio of the total carbon emissions in processes to make the final products, and this implies indirect carbon emission flow across industries. Understanding these flows is crucial for allocating a carbon allowance for each industry. By combining input-output analysis and complex network theory, this study establishes an indirect carbon emission flow network (ICEFN) for 41 industries from 2005 to 2014 to investigate the interrelationships among different industries. The results show that the ICEFN was consistent with a small-world nature based on an analysis of the average path lengths and the clustering coefficients. Moreover, key industries in the ICEFN were identified using complex network theory on the basis of degree centrality and betweenness centrality. Furthermore, the 41 industries of the ICEFN were divided into four industrial subgroups that are related closely to one another. Finally, possible policy implications were provided based on the knowledge of the structure of the ICEFN and its trend.

The ironic effect of guessing: increased false memory for mediated lists in younger and older adults

PubMed Central

Coane, Jennifer H.; Huff, Mark J.; Hutchison, Keith A.

2016-01-01

Younger and older adults studied lists of words directly (e.g., creek, water) or indirectly (e.g., beaver, faucet) related to a nonpresented critical lure (CL; e.g., river). Indirect (i.e., mediated) lists presented items that were only related to CLs through nonpresented mediators (i.e., directly related items). Following study, participants completed a condition-specific task, math, a recall test with or without a warning about the CL, or tried to guess the CL. On a final recognition test, warnings (vs. math and recall without warning) decreased false recognition for direct lists, and guessing increased mediated false recognition (an ironic effect of guessing) in both age groups. The observed age-invariance of the ironic effect of guessing suggests that processes involved in mediated false memory are preserved in aging and confirms the effect is largely due to activation in semantic networks during encoding and to the strengthening of these networks during the interpolated tasks. PMID:26393390

The ironic effect of guessing: increased false memory for mediated lists in younger and older adults.

PubMed

Coane, Jennifer H; Huff, Mark J; Hutchison, Keith A

2016-01-01

Younger and older adults studied lists of words directly (e.g., creek, water) or indirectly (e.g., beaver, faucet) related to a nonpresented critical lure (CL; e.g., river). Indirect (i.e., mediated) lists presented items that were only related to CLs through nonpresented mediators (i.e., directly related items). Following study, participants completed a condition-specific task, math, a recall test with or without a warning about the CL, or tried to guess the CL. On a final recognition test, warnings (vs. math and recall without warning) decreased false recognition for direct lists, and guessing increased mediated false recognition (an ironic effect of guessing) in both age groups. The observed age-invariance of the ironic effect of guessing suggests that processes involved in mediated false memory are preserved in aging and confirms the effect is largely due to activation in semantic networks during encoding and to the strengthening of these networks during the interpolated tasks.

Cytokines and cytokine networks target neurons to modulate long-term potentiation.

PubMed

Prieto, G Aleph; Cotman, Carl W

2017-04-01

Cytokines play crucial roles in the communication between brain cells including neurons and glia, as well as in the brain-periphery interactions. In the brain, cytokines modulate long-term potentiation (LTP), a cellular correlate of memory. Whether cytokines regulate LTP by direct effects on neurons or by indirect mechanisms mediated by non-neuronal cells is poorly understood. Elucidating neuron-specific effects of cytokines has been challenging because most brain cells express cytokine receptors. Moreover, cytokines commonly increase the expression of multiple cytokines in their target cells, thus increasing the complexity of brain cytokine networks even after single-cytokine challenges. Here, we review evidence on both direct and indirect-mediated modulation of LTP by cytokines. We also describe novel approaches based on neuron- and synaptosome-enriched systems to identify cytokines able to directly modulate LTP, by targeting neurons and synapses. These approaches can test multiple samples in parallel, thus allowing the study of multiple cytokines simultaneously. Hence, a cytokine networks perspective coupled with neuron-specific analysis may contribute to delineation of maps of the modulation of LTP by cytokines. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cytokines and cytokine networks target neurons to modulate long-term potentiation

PubMed Central

Prieto, G. Aleph; Cotman, Carl W.

2017-01-01

Cytokines play crucial roles in the communication between brain cells including neurons and glia, as well as in the brain-periphery interactions. In the brain, cytokines modulate long-term potentiation (LTP), a cellular correlate of memory. Whether cytokines regulate LTP by direct effects on neurons or by indirect mechanisms mediated by non-neuronal cells is poorly understood. Elucidating neuron-specific effects of cytokines has been challenging because most brain cells express cytokine receptors. Moreover, cytokines commonly increase the expression of multiple cytokines in their target cells, thus increasing the complexity of brain cytokine networks even after single-cytokine challenges. Here, we review evidence on both direct and indirect-mediated modulation of LTP by cytokines. We also describe novel approaches based on neuron- and synaptosome-enriched systems to identify cytokines able to directly modulate LTP, by targeting neurons and synapses. These approaches can test multiple samples in parallel, thus allowing the study of multiple cytokines simultaneously. Hence, a cytokine networks perspective coupled with neuron-specific analysis may contribute to delineation of maps of the modulation of LTP by cytokines. PMID:28377062

Direct and Indirect Peer Socialization of Adolescent Nonsuicidal Self-Injury

PubMed Central

Giletta, Matteo; Burk, William J.; Scholte, Ron H. J.; Engels, Rutger C. M. E.; Prinstein, Mitchell J.

2015-01-01

This study examined direct and indirect forms of peer socialization of non-suicidal self-injury (NSSI) in adolescent friendship networks. Data were collected among 348 adolescents (55% females; Mage = 15.02 years; SD = 0.53) at 4 assessment waves. Stochastic actor-based models revealed no evidence for direct socialization of NSSI: adolescents whose friends reported higher NSSI did not increase their NSSI over time. However, indirect forms of socialization were found. After controlling for direct socialization and selection effects, friends’ depressive symptoms predicted changes in male and female adolescents’ NSSI and friends’ impulsivity predicted changes in male adolescents’ NSSI. Findings highlight the importance of extending peer influence research beyond the classical “modeling” paradigm by providing evidence that peers may indirectly socialize adolescents’ NSSI. PMID:26412955

Neuronal interactions between mentalising and action systems during indirect request processing.

PubMed

van Ackeren, Markus J; Smaragdi, Areti; Rueschemeyer, Shirley-Ann

2016-09-01

Human communication relies on the ability to process linguistic structure and to map words and utterances onto our environment. Furthermore, as what we communicate is often not directly encoded in our language (e.g. in the case of irony, jokes or indirect requests), we need to extract additional cues to infer the beliefs and desires of our conversational partners. Although the functional interplay between language and the ability to mentalise has been discussed in theoretical accounts in the past, the neurobiological underpinnings of these dynamics are currently not well understood. Here, we address this issue using functional imaging (fMRI). Participants listened to question-reply dialogues. In these dialogues, a reply is interpreted as a direct reply, an indirect reply or a request for action, depending on the question. We show that inferring meaning from indirect replies engages parts of the mentalising network (mPFC) while requests for action also activate the cortical motor system (IPL). Subsequent connectivity analysis using Dynamic Causal Modelling (DCM) revealed that this pattern of activation is best explained by an increase in effective connectivity from the mentalising network (mPFC) to the action system (IPL). These results are an important step towards a more integrative understanding of the neurobiological basis of indirect speech processing. © The Author (2016). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Social support and social undermining as explanatory factors for health-related quality of life in people living with HIV/AIDS.

PubMed

Oetzel, John; Wilcox, Bryan; Archiopoli, Ashley; Avila, Magdalena; Hell, Cia; Hill, Ricky; Muhammad, Michael

2014-01-01

This study aimed to examine the influence of social support (from personal networks and health care providers) and social undermining (from personal networks) on health-related quality of life (HRQOL; general health perceptions, physical functioning, and depression). Specifically, the authors aimed to identify the nature of the effects (direct, mediating, or moderating) of social support and social undermining on HRQOL. A total of 344 people living with HIV/AIDS and who were patients in a federally funded clinic in New Mexico completed a self-report survey questionnaire. The major findings of this study are the following: (a) social support and social undermining had direct and indirect effects on HRQOL-there was no evidence of a moderating effect of social support and social undermining; (b) for direct effects, social undermining was a stronger predictor of HRQOL than social support with social support variables having positive relations and social undermining variables having negative relations with HRQOL; and (c) for indirect effects, providers' social support partially mediated the influence of unstable employment/unemployment and social undermining on HRQOL.

Reversible large–scale modification of cortical networks during neuroprosthetic control

PubMed Central

Ganguly, Karunesh; Wallis, Jonathan D.

2012-01-01

Brain-Machine Interfaces (BMI) provide a framework to study cortical dynamics and the neural correlates of learning. Neuroprosthetic control has been associated with tuning changes in specific neurons directly projecting to the BMI (hereafter ‘direct neurons’). However, little is known about the larger network dynamics. By monitoring ensembles of neurons that were either causally linked to BMI control or indirectly involved, here we show that proficient neuroprosthetic control is associated with large-scale modifications to the cortical network in macaque monkeys. Specifically, there were changes in the preferred direction of both direct and indirect neurons. Interestingly, with learning, there was a relative decrease in the net modulation of indirect neural activity in comparison to the direct activity. These widespread differential changes in the direct and indirect population activity were remarkably stable from one day to the next and readily coexisted with the long-standing cortical network for upper limb control. Thus, the process of learning BMI control is associated with differential modification of neural populations based on their specific relation to movement control. PMID:21499255

Reversible large-scale modification of cortical networks during neuroprosthetic control.

PubMed

Ganguly, Karunesh; Dimitrov, Dragan F; Wallis, Jonathan D; Carmena, Jose M

2011-05-01

Brain-machine interfaces (BMIs) provide a framework for studying cortical dynamics and the neural correlates of learning. Neuroprosthetic control has been associated with tuning changes in specific neurons directly projecting to the BMI (hereafter referred to as direct neurons). However, little is known about the larger network dynamics. By monitoring ensembles of neurons that were either causally linked to BMI control or indirectly involved, we found that proficient neuroprosthetic control is associated with large-scale modifications to the cortical network in macaque monkeys. Specifically, there were changes in the preferred direction of both direct and indirect neurons. Notably, with learning, there was a relative decrease in the net modulation of indirect neural activity in comparison with direct activity. These widespread differential changes in the direct and indirect population activity were markedly stable from one day to the next and readily coexisted with the long-standing cortical network for upper limb control. Thus, the process of learning BMI control is associated with differential modification of neural populations based on their specific relation to movement control.

Indirect economic impact of landslide hazards by disruption to national road transportation networks; Scotland, United Kingdom.

NASA Astrophysics Data System (ADS)

Postance, Benjamin; Hillier, John; Dijkstra, Tom; Dixon, Neil

2016-04-01

The failure of engineered or natural slopes which support or are adjacent to transportation systems often inflicts costly direct physical damage and indirect system disruption. The consequences and severity of indirect impacts vary according to which links, nodes or network facilities are physically disrupted. Moreover, it is often the case that multiple slope failure disruptions are triggered simultaneously following prolonged or intense precipitation events due to a degree of local homogeneity of slope characteristics and materials. This study investigates the application of national commuter statistics and network agent simulation to evaluate indirect impacts of landslide events disrupting the Scottish trunk road transportation network (UK). Previous studies often employ shortest pathway analysis whereas agent simulation has received relatively little attention. British Geological Survey GeoSure landslide susceptibility data is used to select 35 susceptible trunk road segments by means of neighbouring total area at risk. For each of the candidate 35 segments the network and zonal variation in travel time is calculated for a single day of disruption, economic impact is approximated using established governmental and industry transport planning and appraisal values. The results highlight that a number of trunk road segments incur indirect economic losses in the order of tens of thousands of pounds for each day of closure. Calculated losses at the A83 Rest and Be Thankful are 50% greater than previous estimates at £75 thousand per day of closure. Also highlighted are events in which economic impact is relatively minor, yet concentrating on particular communities that can become substantially isolated as a consequence of a single event. The findings of this study are of interest and support wider investigations exploring cost considerations for decision makers and mitigation strategies, in addition to identifying network topological and demand indicators conducive to high indirect economic cost events.

Indirect effects of parasitism: costs of infection to other individuals can be greater than direct costs borne by the host.

PubMed

Granroth-Wilding, Hanna M V; Burthe, Sarah J; Lewis, Sue; Herborn, Katherine A; Takahashi, Emi A; Daunt, Francis; Cunningham, Emma J A

2015-07-22

Parasitic infection has a direct physiological cost to hosts but may also alter how hosts interact with other individuals in their environment. Such indirect effects may alter both host fitness and the fitness of other individuals in the host's social network, yet the relative impact of direct and indirect effects of infection are rarely quantified. During reproduction, a host's social environment includes family members who may be in conflict over resource allocation. In such situations, infection may alter how resources are allocated, thereby redistributing the costs of parasitism between individuals. Here, we experimentally reduce parasite burdens of parent and/or nestling European shags (Phalacrocorax aristotelis) infected with Contracaecum nematodes in a factorial design, then simultaneously measure the impact of an individual's infection on all family members. We found no direct effect of infection on parent or offspring traits but indirect effects were detected in all group members, with both immediate effects (mass change and survival) and longer-term effects (timing of parents' subsequent breeding). Our results show that parasite infection can have a major impact on individuals other than the host, suggesting that the effect of parasites on population processes may be greater than previously thought. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Direct and Indirect Influence of Altruistic Behavior in a Social Network.

PubMed

Liu, Pei-Pei; Safin, Vasiliy; Yang, Barry; Luhmann, Christian C

2015-01-01

Prior research has suggested that recipients of generosity behave more generously themselves (a direct social influence). In contrast, there is conflicting evidence about the existence of indirect influence (i.e., whether interacting with a recipient of generosity causes one to behave more generously), casting doubt on the possibility that altruistic behavior can cascade through social networks. The current study investigated how far selfish and generous behavior can be transmitted through social networks and the cognitive mechanisms that underlie such transmission. Participants played a sequence of public goods games comprising a chain network. This network is advantageous because it permits only a single, unambiguous path of influence. Furthermore, we experimentally manipulated the behavior of the first link in the chain to be either generous or selfish. Results revealed the presence of direct social influence, but no evidence for indirect influence. Results also showed that selfish behavior exerted a substantially greater influence than generous behavior. Finally, expectations about future partners' behavior strongly mediated the observed social influence, suggesting an adaptive basis for such influence.

Real medical benefit assessed by indirect comparison.

PubMed

Falissard, Bruno; Zylberman, Myriam; Cucherat, Michel; Izard, Valérie; Meyer, François

2009-01-01

Frequently, in data packages submitted for Marketing Approval to the CHMP, there is a lack of relevant head-to-head comparisons of medicinal products that could enable national authorities responsible for the approval of reimbursement to assess the Added Therapeutic Value (ASMR) of new clinical entities or line extensions of existing therapies.Indirect or mixed treatment comparisons (MTC) are methods stemming from the field of meta-analysis that have been designed to tackle this problem. Adjusted indirect comparisons, meta-regressions, mixed models, Bayesian network analyses pool results of randomised controlled trials (RCTs), enabling a quantitative synthesis.The REAL procedure, recently developed by the HAS (French National Authority for Health), is a mixture of an MTC and effect model based on expert opinions. It is intended to translate the efficacy observed in the trials into effectiveness expected in day-to-day clinical practice in France.

Relay discovery and selection for large-scale P2P streaming

PubMed Central

Zhang, Chengwei; Wang, Angela Yunxian

2017-01-01

In peer-to-peer networks, application relays have been commonly used to provide various networking services. The service performance often improves significantly if a relay is selected appropriately based on its network location. In this paper, we studied the location-aware relay discovery and selection problem for large-scale P2P streaming networks. In these large-scale and dynamic overlays, it incurs significant communication and computation cost to discover a sufficiently large relay candidate set and further to select one relay with good performance. The network location can be measured directly or indirectly with the tradeoffs between timeliness, overhead and accuracy. Based on a measurement study and the associated error analysis, we demonstrate that indirect measurements, such as King and Internet Coordinate Systems (ICS), can only achieve a coarse estimation of peers’ network location and those methods based on pure indirect measurements cannot lead to a good relay selection. We also demonstrate that there exists significant error amplification of the commonly used “best-out-of-K” selection methodology using three RTT data sets publicly available. We propose a two-phase approach to achieve efficient relay discovery and accurate relay selection. Indirect measurements are used to narrow down a small number of high-quality relay candidates and the final relay selection is refined based on direct probing. This two-phase approach enjoys an efficient implementation using the Distributed-Hash-Table (DHT). When the DHT is constructed, the node keys carry the location information and they are generated scalably using indirect measurements, such as the ICS coordinates. The relay discovery is achieved efficiently utilizing the DHT-based search. We evaluated various aspects of this DHT-based approach, including the DHT indexing procedure, key generation under peer churn and message costs. PMID:28410384

Relay discovery and selection for large-scale P2P streaming.

PubMed

Zhang, Chengwei; Wang, Angela Yunxian; Hei, Xiaojun

2017-01-01

In peer-to-peer networks, application relays have been commonly used to provide various networking services. The service performance often improves significantly if a relay is selected appropriately based on its network location. In this paper, we studied the location-aware relay discovery and selection problem for large-scale P2P streaming networks. In these large-scale and dynamic overlays, it incurs significant communication and computation cost to discover a sufficiently large relay candidate set and further to select one relay with good performance. The network location can be measured directly or indirectly with the tradeoffs between timeliness, overhead and accuracy. Based on a measurement study and the associated error analysis, we demonstrate that indirect measurements, such as King and Internet Coordinate Systems (ICS), can only achieve a coarse estimation of peers' network location and those methods based on pure indirect measurements cannot lead to a good relay selection. We also demonstrate that there exists significant error amplification of the commonly used "best-out-of-K" selection methodology using three RTT data sets publicly available. We propose a two-phase approach to achieve efficient relay discovery and accurate relay selection. Indirect measurements are used to narrow down a small number of high-quality relay candidates and the final relay selection is refined based on direct probing. This two-phase approach enjoys an efficient implementation using the Distributed-Hash-Table (DHT). When the DHT is constructed, the node keys carry the location information and they are generated scalably using indirect measurements, such as the ICS coordinates. The relay discovery is achieved efficiently utilizing the DHT-based search. We evaluated various aspects of this DHT-based approach, including the DHT indexing procedure, key generation under peer churn and message costs.

Assessing the indirect effects due to natural hazards on a mesoscale

NASA Astrophysics Data System (ADS)

Pfurtscheller, C.; Schwarze, R.

2009-04-01

Measuring indirect economic costs and other effects from natural hazards, especially floods in alpine and other mountainous regions, are a necessary part of a comprehensive economic assessment. Their omission seriously affects the relative economic benefits of structural or non structural measures of flood defence. Surpassing controversial, IO-model-based economic estimates, analysing indirect economic effects lead to the key question of identifying and evaluating the drivers of indirect economic effects and resilience to system effects in the regional economy, i.e. at the meso-level. This investigation takes place for the catastrophic floods in summer 2005 in the provinces of Tyrol and Vorarlberg, Austria, which caused an estimated € 670 Mio direct loss on private and public assets and severe interruptions in lifeline services. The paper starts out with differentiating the concept of indirect economic costs from direct costs, examing different temporal (short vs. long-term) and spatial (macro-, meso- vs. microeconomic) system boundaries. It surveys common theories of economic resilience and vulnerability at the regional economy level. Indirect effects at the regional economy level can be defined as interferences of the economic exchange of goods and services triggered by breakdowns of transport lines and critical production inputs. The extent and persistence of indirect effects of natural hazards is not only by parameters of the extreme event, such as duration and amplitude of the flood, but much more by resilience parameters of the regional economy such as size of enterprises, the network structure (linkages) of the regional economy, availability of insurance and relief funds, and the stock of inventory. These effects can only be dissected by means of expert judgement and event studies. This paper presents the results of a survey conducted among business practioneers, members of chamber of commerce, civil protection agencies to identify and scale the drivers of indirect costs triggered by floods on a local and regional scale. We develop a risk point scale and explain how it can be nested into IO-model-based economic tools such as the HAZUS indirect economic loss calculator

Applications of Social Network Analysis

NASA Astrophysics Data System (ADS)

Thilagam, P. Santhi

A social network [2] is a description of the social structure between actors, mostly persons, groups or organizations. It indicates the ways in which they are connected with each other by some relationship such as friendship, kinship, finance exchange etc. In a nutshell, when the person uses already known/unknown people to create new contacts, it forms social networking. The social network is not a new concept rather it can be formed when similar people interact with each other directly or indirectly to perform particular task. Examples of social networks include a friendship networks, collaboration networks, co-authorship networks, and co-employees networks which depict the direct interaction among the people. There are also other forms of social networks, such as entertainment networks, business Networks, citation networks, and hyperlink networks, in which interaction among the people is indirect. Generally, social networks operate on many levels, from families up to the level of nations and assists in improving interactive knowledge sharing, interoperability and collaboration.

Cascades of emotional support in friendship networks and adolescent smoking

PubMed Central

Wang, Cheng; Butts, Carter T.; Jose, Rupa; Hipp, John R.

2017-01-01

Social support from peers and parents provides a key socialization function during adolescence. We examine adolescent friendship networks using a Stochastic Actor-Based modeling approach to observe the flow of emotional support provision to peers and the effect of support from parents, while simultaneously modeling smoking behavior. We utilized one school (n = 976) from The National Longitudinal Study of Adolescent to Adult Health (AddHealth) Study. Our findings suggest that emotional support is transacted through an interdependent contextual system, comprised of both peer and parental effects, with the latter also having distal indirect effects from youths’ friends’ parents. PMID:28662121

Modelling indirect interactions during failure spreading in a project activity network.

PubMed

Ellinas, Christos

2018-03-12

Spreading broadly refers to the notion of an entity propagating throughout a networked system via its interacting components. Evidence of its ubiquity and severity can be seen in a range of phenomena, from disease epidemics to financial systemic risk. In order to understand the dynamics of these critical phenomena, computational models map the probability of propagation as a function of direct exposure, typically in the form of pairwise interactions between components. By doing so, the important role of indirect interactions remains unexplored. In response, we develop a simple model that accounts for the effect of both direct and subsequent exposure, which we deploy in the novel context of failure propagation within a real-world engineering project. We show that subsequent exposure has a significant effect in key aspects, including the: (a) final spreading event size, (b) propagation rate, and (c) spreading event structure. In addition, we demonstrate the existence of 'hidden influentials' in large-scale spreading events, and evaluate the role of direct and subsequent exposure in their emergence. Given the evidence of the importance of subsequent exposure, our findings offer new insight on particular aspects that need to be included when modelling network dynamics in general, and spreading processes specifically.

Evidence synthesis for decision making 7: a reviewer's checklist.

PubMed

Ades, A E; Caldwell, Deborah M; Reken, Stefanie; Welton, Nicky J; Sutton, Alex J; Dias, Sofia

2013-07-01

This checklist is for the review of evidence syntheses for treatment efficacy used in decision making based on either efficacy or cost-effectiveness. It is intended to be used for pairwise meta-analysis, indirect comparisons, and network meta-analysis, without distinction. It does not generate a quality rating and is not prescriptive. Instead, it focuses on a series of questions aimed at revealing the assumptions that the authors of the synthesis are expecting readers to accept, the adequacy of the arguments authors advance in support of their position, and the need for further analyses or sensitivity analyses. The checklist is intended primarily for those who review evidence syntheses, including indirect comparisons and network meta-analyses, in the context of decision making but will also be of value to those submitting syntheses for review, whether to decision-making bodies or journals. The checklist has 4 main headings: A) definition of the decision problem, B) methods of analysis and presentation of results, C) issues specific to network synthesis, and D) embedding the synthesis in a probabilistic cost-effectiveness model. The headings and implicit advice follow directly from the other tutorials in this series. A simple table is provided that could serve as a pro forma checklist.

A structural equation model analysis of relationships among ENSO, seasonal descriptors and wildfires.

PubMed

Slocum, Matthew G; Orzell, Steve L

2013-01-01

Seasonality drives ecological processes through networks of forcings, and the resultant complexity requires creative approaches for modeling to be successful. Recently ecologists and climatologists have developed sophisticated methods for fully describing seasons. However, to date the relationships among the variables produced by these methods have not been analyzed as networks, but rather with simple univariate statistics. In this manuscript we used structural equation modeling (SEM) to analyze a proposed causal network describing seasonality of rainfall for a site in south-central Florida. We also described how this network was influenced by the El Niño-Southern Oscillation (ENSO), and how the network in turn affected the site's wildfire regime. Our models indicated that wet and dry seasons starting later in the year (or ending earlier) were shorter and had less rainfall. El Niño conditions increased dry season rainfall, and via this effect decreased the consistency of that season's drying trend. El Niño conditions also negatively influenced how consistent the moistening trend was during the wet season, but in this case the effect was direct and did not route through rainfall. In modeling wildfires, our models showed that area burned was indirectly influenced by ENSO via its effect on dry season rainfall. Area burned was also indirectly reduced when the wet season had consistent rainfall, as such wet seasons allowed fewer wildfires in subsequent fire seasons. Overall area burned at the study site was estimated with high accuracy (R (2) score = 0.63). In summary, we found that by using SEMs, we were able to clearly describe causal patterns involving seasonal climate, ENSO and wildfire. We propose that similar approaches could be effectively applied to other sites where seasonality exerts strong and complex forcings on ecological processes.

A Structural Equation Model Analysis of Relationships among ENSO, Seasonal Descriptors and Wildfires

PubMed Central

Slocum, Matthew G.; Orzell, Steve L.

2013-01-01

Seasonality drives ecological processes through networks of forcings, and the resultant complexity requires creative approaches for modeling to be successful. Recently ecologists and climatologists have developed sophisticated methods for fully describing seasons. However, to date the relationships among the variables produced by these methods have not been analyzed as networks, but rather with simple univariate statistics. In this manuscript we used structural equation modeling (SEM) to analyze a proposed causal network describing seasonality of rainfall for a site in south-central Florida. We also described how this network was influenced by the El Niño-Southern Oscillation (ENSO), and how the network in turn affected the site’s wildfire regime. Our models indicated that wet and dry seasons starting later in the year (or ending earlier) were shorter and had less rainfall. El Niño conditions increased dry season rainfall, and via this effect decreased the consistency of that season’s drying trend. El Niño conditions also negatively influenced how consistent the moistening trend was during the wet season, but in this case the effect was direct and did not route through rainfall. In modeling wildfires, our models showed that area burned was indirectly influenced by ENSO via its effect on dry season rainfall. Area burned was also indirectly reduced when the wet season had consistent rainfall, as such wet seasons allowed fewer wildfires in subsequent fire seasons. Overall area burned at the study site was estimated with high accuracy (R 2 score = 0.63). In summary, we found that by using SEMs, we were able to clearly describe causal patterns involving seasonal climate, ENSO and wildfire. We propose that similar approaches could be effectively applied to other sites where seasonality exerts strong and complex forcings on ecological processes. PMID:24086670

Modeling an impact of road geometric design on vehicle energy consumption

NASA Astrophysics Data System (ADS)

Luin, Blaž; Petelin, Stojan; Al-Mansour, Fouad

2017-11-01

Some roads connect traffic origins and destinations directly, some use winding, indirect routes. Indirect connections result in longer distances driven and increased fuel consumption. A similar effect is observed on congested roads and mountain roads with many changes in altitude. Therefore a framework to assess road networks based on energy consumption is proposed. It has been shown that road geometry has significant impact on overall traffic energy consumption and emissions. The methodology presented in the paper analyzes impact of traffic volume, shares of vehicle classes, road network configuration on the energy used by the vehicles. It can be used to optimize energy consumption with efficient traffic management and to choose optimum new road in the design phase. This is especially important as the energy consumed by the vehicles shortly after construction supersedes the energy spent for the road construction.

The potential indirect effects among plants via shared hummingbird pollinators are structured by phenotypic similarity.

PubMed

Bergamo, Pedro Joaquim; Wolowski, Marina; Maruyama, Pietro Kiyoshi; Vizentin-Bugoni, Jeferson; Carvalheiro, Luísa G; Sazima, Marlies

2017-07-01

Plant species within communities may overlap in pollinators' use and influence visitation patterns of shared pollinators, potentially engaging in indirect interactions (e.g., facilitation or competition). While several studies have explored the mechanisms regulating insect-pollination networks, there is a lack of studies on bird-pollination systems, particularly in species-rich tropical areas. Here, we evaluated if phenotypic similarity, resource availability (floral abundance), evolutionary relatedness and flowering phenology affect the potential for indirect effects via shared pollinators in hummingbird-pollinated plant species within four communities in the Brazilian Atlantic forest. Among the evaluated factors, phenotypic similarity (corolla length and anther height) was the most important variable, while resource availability (floral abundance) had a secondary importance. On the other hand, evolutionary relatedness and flowering phenology were less important, which altogether highlights the relevance of convergent evolution and that the contribution of a plant to the diet of the pollinators of another plant is independent of the level of temporal overlap in flowering in this tropical system. Interestingly, our findings contrast with results from multiple insect-pollinated plant communities, mostly from temperate regions, in which floral abundance was the most important driver, followed by evolutionary relatedness and phenotypic similarity. We propose that these contrasting results are due to high level of specialization inherent to tropical hummingbird-pollination systems. Moreover, our results demonstrated that factors defining linkage rules of plant-hummingbird networks also determinate plant-plant potential indirect effects. Future studies are needed to test if these findings can be generalized to other highly specialized systems. Overall, our results have important implications for the understanding of ecological processes due resource sharing in mutualistic systems. © 2017 by the Ecological Society of America.

The Competitive Position of Hub Airports in the Transatlantic Market

NASA Technical Reports Server (NTRS)

Burghouwt, Guillaume; Veldhuis, Jan

2006-01-01

This article puts forward the argument that the measurement of connectivity in hub-and-spoke networks has to take into account the quality and quantity of both direct and indirect connections. The NETSCAN model, which has been applied in this study, quantifies indirect connectivity and scales it into a theoretical direct connection. NETSCAN allows researchers, airports, airlines, alliances and airport regions to analyse their competitive position in an integrated way. Using NETSCAN, the authors analysed the developments on the market between northwest Europe and the United States (US) between May 2003 and May 2005. One of the most striking developments has certainly been the impact of the Air France-KLM merger and the effects of the integration of KLM and Northwest into the SkyTeam alliance on the connectivity of Amsterdam Schiphol. Direct as well as indirect connectivity (via European and North American hubs) from Amsterdam to the US increased substantially. The main reason for this increase is the integration of the former Wings and SkyTeam networks via the respective hub airports. Moreover, the extended SkyTeam alliance raised frequencies between Amsterdam and the SkyTeam hubs (Atlanta, Houston, for example), opened new routes (Cincinnati) and boosted the network between Amsterdam and France. As a result of the new routes and frequencies, Amsterdam took over Heathrow s position as the third best-connected northwest European airport to the US.

Direct and indirect effects of third-party relationships on interpersonal trust.

PubMed

Ferrin, Donald L; Dirks, Kurt T; Shah, Pri P

2006-07-01

Past studies of the determinants of interpersonal trust have focused primarily on how trust forms in isolated dyads. Yet within organizations, trust typically develops between individuals who are embedded in a complex web of existing and potential relationships. In this article, the authors identify 3 alternative ways in which a trustor and trustee may be linked to each other via third parties: network closure (linked via social interactions with third parties), trust transferability (linked via trusted third parties), and structural equivalence (linked via the similarity of their relationships with all potential third parties within the organization). Each of these is argued to influence interpersonal trust via a distinct social mechanism. The authors hypothesized that network closure and structural equivalence would predict interpersonal trust indirectly via their impact on interpersonal organizational citizenship behaviors performed within the interpersonal relationship, whereas trust transferability would predict trust directly. Social network analyses of data gathered from a medium-sized work organization provide substantial support for the hypotheses and also suggest important directions for future research. ((c) 2006 APA, all rights reserved).

Ecological network analysis on global virtual water trade.

PubMed

Yang, Zhifeng; Mao, Xufeng; Zhao, Xu; Chen, Bin

2012-02-07

Global water interdependencies are likely to increase with growing virtual water trade. To address the issues of the indirect effects of water trade through the global economic circulation, we use ecological network analysis (ENA) to shed insight into the complicated system interactions. A global model of virtual water flow among agriculture and livestock production trade in 1995-1999 is also built as the basis for network analysis. Control analysis is used to identify the quantitative control or dependency relations. The utility analysis provides more indicators for describing the mutual relationship between two regions/countries by imitating the interactions in the ecosystem and distinguishes the beneficiary and the contributor of virtual water trade system. Results show control and utility relations can well depict the mutual relation in trade system, and direct observable relations differ from integral ones with indirect interactions considered. This paper offers a new way to depict the interrelations between trade components and can serve as a meaningful start as we continue to use ENA in providing more valuable implications for freshwater study on a global scale.

[Basic concepts for network meta-analysis].

PubMed

Catalá-López, Ferrán; Tobías, Aurelio; Roqué, Marta

2014-12-01

Systematic reviews and meta-analyses have long been fundamental tools for evidence-based clinical practice. Initially, meta-analyses were proposed as a technique that could improve the accuracy and the statistical power of previous research from individual studies with small sample size. However, one of its main limitations has been the fact of being able to compare no more than two treatments in an analysis, even when the clinical research question necessitates that we compare multiple interventions. Network meta-analysis (NMA) uses novel statistical methods that incorporate information from both direct and indirect treatment comparisons in a network of studies examining the effects of various competing treatments, estimating comparisons between many treatments in a single analysis. Despite its potential limitations, NMA applications in clinical epidemiology can be of great value in situations where there are several treatments that have been compared against a common comparator. Also, NMA can be relevant to a research or clinical question when many treatments must be considered or when there is a mix of both direct and indirect information in the body of evidence. Copyright © 2013 Elsevier España, S.L.U. All rights reserved.

Network Mendelian randomization: using genetic variants as instrumental variables to investigate mediation in causal pathways

PubMed Central

Burgess, Stephen; Daniel, Rhian M; Butterworth, Adam S; Thompson, Simon G

2015-01-01

Background: Mendelian randomization uses genetic variants, assumed to be instrumental variables for a particular exposure, to estimate the causal effect of that exposure on an outcome. If the instrumental variable criteria are satisfied, the resulting estimator is consistent even in the presence of unmeasured confounding and reverse causation. Methods: We extend the Mendelian randomization paradigm to investigate more complex networks of relationships between variables, in particular where some of the effect of an exposure on the outcome may operate through an intermediate variable (a mediator). If instrumental variables for the exposure and mediator are available, direct and indirect effects of the exposure on the outcome can be estimated, for example using either a regression-based method or structural equation models. The direction of effect between the exposure and a possible mediator can also be assessed. Methods are illustrated in an applied example considering causal relationships between body mass index, C-reactive protein and uric acid. Results: These estimators are consistent in the presence of unmeasured confounding if, in addition to the instrumental variable assumptions, the effects of both the exposure on the mediator and the mediator on the outcome are homogeneous across individuals and linear without interactions. Nevertheless, a simulation study demonstrates that even considerable heterogeneity in these effects does not lead to bias in the estimates. Conclusions: These methods can be used to estimate direct and indirect causal effects in a mediation setting, and have potential for the investigation of more complex networks between multiple interrelated exposures and disease outcomes. PMID:25150977

Comparative study on individual aromatase inhibitors on cardiovascular safety profile: a network meta-analysis

PubMed Central

Zhao, Xihe; Liu, Lei; Li, Kai; Li, Wusheng; Zhao, Li; Zou, Huawei

2015-01-01

The third-generation aromatase inhibitors (AIs: anastrozole, letrozole, and exemestane) have now become standard adjuvant endocrine treatment for postmenopausal estrogen receptor-positive breast cancer complementing chemotherapy and surgery. Because of the absence of direct head-to-head comparisons of these AIs, an indirect comparison is needed for individual treatment choice. In this network systemic assessment, the cardiovascular (CV) side effects in using anastrozole, letrozole, and exemestane based on original studies on AIs vs placebo or tamoxifen were compared. We integrated all available direct and indirect evidences. The odds ratio (OR) of severe CV events for indirect comparisons between exemestane and anastrozole was 1.41 (95% confidence interval [CI] =0.49–2.78), letrozole and anastrozole was 1.80 (95% CI =0.40–3.92), and letrozole and exemestane was 1.46 (95% CI =0.34–3.4). OR of subgroup risk for AIs and tamoxifen were all >1 except for thrombolism risk subgroup. The results showed that the total and severe CV risk ranking is letrozole, exemestane, and anastrozole in descending order. None of the AIs showed advantages in CV events than tamoxifen except for thromboembolism event incidence. PMID:26491345

Advanced lesion symptom mapping analyses and implementation as BCBtoolkit.

PubMed

Foulon, Chris; Cerliani, Leonardo; Kinkingnéhun, Serge; Levy, Richard; Rosso, Charlotte; Urbanski, Marika; Volle, Emmanuelle; Thiebaut de Schotten, Michel

2018-03-01

Patients with brain lesions provide a unique opportunity to understand the functioning of the human mind. However, even when focal, brain lesions have local and remote effects that impact functionally and structurally connected circuits. Similarly, function emerges from the interaction between brain areas rather than their sole activity. For instance, category fluency requires the associations between executive, semantic, and language production functions. Here, we provide, for the first time, a set of complementary solutions for measuring the impact of a given lesion on the neuronal circuits. Our methods, which were applied to 37 patients with a focal frontal brain lesions, revealed a large set of directly and indirectly disconnected brain regions that had significantly impacted category fluency performance. The directly disconnected regions corresponded to areas that are classically considered as functionally engaged in verbal fluency and categorization tasks. These regions were also organized into larger directly and indirectly disconnected functional networks, including the left ventral fronto-parietal network, whose cortical thickness correlated with performance on category fluency. The combination of structural and functional connectivity together with cortical thickness estimates reveal the remote effects of brain lesions, provide for the identification of the affected networks, and strengthen our understanding of their relationship with cognitive and behavioral measures. The methods presented are available and freely accessible in the BCBtoolkit as supplementary software [1].

Network meta-analysis: an introduction for clinicians.

PubMed

Rouse, Benjamin; Chaimani, Anna; Li, Tianjing

2017-02-01

Network meta-analysis is a technique for comparing multiple treatments simultaneously in a single analysis by combining direct and indirect evidence within a network of randomized controlled trials. Network meta-analysis may assist assessing the comparative effectiveness of different treatments regularly used in clinical practice and, therefore, has become attractive among clinicians. However, if proper caution is not taken in conducting and interpreting network meta-analysis, inferences might be biased. The aim of this paper is to illustrate the process of network meta-analysis with the aid of a working example on first-line medical treatment for primary open-angle glaucoma. We discuss the key assumption of network meta-analysis, as well as the unique considerations for developing appropriate research questions, conducting the literature search, abstracting data, performing qualitative and quantitative synthesis, presenting results, drawing conclusions, and reporting the findings in a network meta-analysis.

Essays on Innovation Ecosystems in the Enterprise Software Industry

ERIC Educational Resources Information Center

Huang, Peng

2010-01-01

Innovation ecosystem strategy is often adopted by platform technology owners to seek complementary innovation from resources located outside the firm to exploit indirect network effect. In this dissertation I aim to address the issues that are related to the formation and business value of platform innovation ecosystems in the enterprise software…

Network meta-analysis: a technique to gather evidence from direct and indirect comparisons

PubMed Central

2017-01-01

Systematic reviews and pairwise meta-analyses of randomized controlled trials, at the intersection of clinical medicine, epidemiology and statistics, are positioned at the top of evidence-based practice hierarchy. These are important tools to base drugs approval, clinical protocols and guidelines formulation and for decision-making. However, this traditional technique only partially yield information that clinicians, patients and policy-makers need to make informed decisions, since it usually compares only two interventions at the time. In the market, regardless the clinical condition under evaluation, usually many interventions are available and few of them have been studied in head-to-head studies. This scenario precludes conclusions to be drawn from comparisons of all interventions profile (e.g. efficacy and safety). The recent development and introduction of a new technique – usually referred as network meta-analysis, indirect meta-analysis, multiple or mixed treatment comparisons – has allowed the estimation of metrics for all possible comparisons in the same model, simultaneously gathering direct and indirect evidence. Over the last years this statistical tool has matured as technique with models available for all types of raw data, producing different pooled effect measures, using both Frequentist and Bayesian frameworks, with different software packages. However, the conduction, report and interpretation of network meta-analysis still poses multiple challenges that should be carefully considered, especially because this technique inherits all assumptions from pairwise meta-analysis but with increased complexity. Thus, we aim to provide a basic explanation of network meta-analysis conduction, highlighting its risks and benefits for evidence-based practice, including information on statistical methods evolution, assumptions and steps for performing the analysis. PMID:28503228

A trust evaluation algorithm for wireless sensor networks based on node behaviors and D-S evidence theory.

PubMed

Feng, Renjian; Xu, Xiaofeng; Zhou, Xiang; Wan, Jiangwen

2011-01-01

For wireless sensor networks (WSNs), many factors, such as mutual interference of wireless links, battlefield applications and nodes exposed to the environment without good physical protection, result in the sensor nodes being more vulnerable to be attacked and compromised. In order to address this network security problem, a novel trust evaluation algorithm defined as NBBTE (Node Behavioral Strategies Banding Belief Theory of the Trust Evaluation Algorithm) is proposed, which integrates the approach of nodes behavioral strategies and modified evidence theory. According to the behaviors of sensor nodes, a variety of trust factors and coefficients related to the network application are established to obtain direct and indirect trust values through calculating weighted average of trust factors. Meanwhile, the fuzzy set method is applied to form the basic input vector of evidence. On this basis, the evidence difference is calculated between the indirect and direct trust values, which link the revised D-S evidence combination rule to finally synthesize integrated trust value of nodes. The simulation results show that NBBTE can effectively identify malicious nodes and reflects the characteristic of trust value that 'hard to acquire and easy to lose'. Furthermore, it is obvious that the proposed scheme has an outstanding advantage in terms of illustrating the real contribution of different nodes to trust evaluation.

A Green's Function Approach to Simulate DNA Damage by the Indirect Effect

NASA Technical Reports Server (NTRS)

Plante, Ianik; Cicinotta, Francis A.

2013-01-01

The DNA damage is of fundamental importance in the understanding of the effects of ionizing radiation. DNA is damaged by the direct effect of radiation (e.g. direct ionization) and by indirect effect (e.g. damage by.OH radicals created by the radiolysis of water). Despite years of research, many questions on the DNA damage by ionizing radiation remains. In the recent years, the Green's functions of the diffusion equation (GFDE) have been used extensively in biochemistry [1], notably to simulate biochemical networks in time and space [2]. In our future work on DNA damage, we wish to use an approach based on the GFDE to refine existing models on the indirect effect of ionizing radiation on DNA. To do so, we will use the code RITRACKS [3] developed at the NASA Johnson Space Center to simulate the radiation track structure and calculate the position of radiolytic species after irradiation. We have also recently developed an efficient Monte-Carlo sampling algorithm for the GFDE of reversible reactions with an intermediate state [4], which can be modified and adapted to simulate DNA damage by free radicals. To do so, we will use the known reaction rate constants between radicals (OH, eaq, H,...) and the DNA bases, sugars and phosphates and use the sampling algorithms to simulate the diffusion of free radicals and chemical reactions with DNA. These techniques should help the understanding of the contribution of the indirect effect in the formation of DNA damage and double-strand breaks.

Perceptions of Services and Resources as Mediators of Depression among Parents of Children with Developmental Disabilities.

ERIC Educational Resources Information Center

Herman, Sandra E.; Marcenko, Maureen O.

1997-01-01

This study examined effects of resource perceptions and respite use in a theoretical model of adaptation with 72 parents of children with developmental disabilities. Amount and quality of respite services indirectly affected parental depression. Both quality and respite use were related to helpfulness of the parent's social network. The strongest…

What is a free customer worth? Armchair calculations of nonpaying customers' value can lead to flawed strategies.

PubMed

Gupta, Sunil; Mela, Carl F

2008-11-01

Free customers who are subsidized by paying customers are essential to a vast array of businesses, such as media companies, employment services, and even IT providers. But because they generate revenue only indirectly, figuring out the true value of those customers--and how much attention to devote them--has always been a challenge. Traditional customer-valuation models don't help; they focus exclusively on paying customers and largely ignore network effects, or how customers help draw other customers to a business. Now a new model, devised by professors Gupta, of Harvard Business School, and Mela, of Fuqua School of Business, takes into account not only direct network effects (where buyers attract more buyers or sellers more sellers) but also indirect network effects (where buyers attract more sellers or vice versa) . The model calculates the precise long-term impact of each additional free customer on a company's profits, factoring in the degree to which he or she brings in other customers--whether free or paying--and the ripple effect of those customers. The model helped an online auction house make several critical decisions. The business made its money on fees charged to sellers but recognized that its free customers--its buyers--were valuable, too. As competition heated up, the company worried that it wasn't wooing enough buyers. Using the model, the business discovered that the network effects of buyers were indeed large and that those customers were worth over $1,000 each--much more than had been assumed. Armed with that information, the firm increased its research on buyers, invested more in targeting them with ads, and improved their experience. The model also helped the company identify the effects of various pricing strategies on sellers, showing that they became less price-sensitive over time. As a result, the company raised the fees it charged them as well.

Mapping eQTL Networks with Mixed Graphical Markov Models

PubMed Central

Tur, Inma; Roverato, Alberto; Castelo, Robert

2014-01-01

Expression quantitative trait loci (eQTL) mapping constitutes a challenging problem due to, among other reasons, the high-dimensional multivariate nature of gene-expression traits. Next to the expression heterogeneity produced by confounding factors and other sources of unwanted variation, indirect effects spread throughout genes as a result of genetic, molecular, and environmental perturbations. From a multivariate perspective one would like to adjust for the effect of all of these factors to end up with a network of direct associations connecting the path from genotype to phenotype. In this article we approach this challenge with mixed graphical Markov models, higher-order conditional independences, and q-order correlation graphs. These models show that additive genetic effects propagate through the network as function of gene–gene correlations. Our estimation of the eQTL network underlying a well-studied yeast data set leads to a sparse structure with more direct genetic and regulatory associations that enable a straightforward comparison of the genetic control of gene expression across chromosomes. Interestingly, it also reveals that eQTLs explain most of the expression variability of network hub genes. PMID:25271303

Short-term efficacy and safety of new biological agents targeting the interleukin-23-T helper 17 pathway for moderate-to-severe plaque psoriasis: a systematic review and network meta-analysis.

PubMed

Gómez-García, F; Epstein, D; Isla-Tejera, B; Lorente, A; Vélez García-Nieto, A; Ruano, J

2017-03-01

A new generation of biologics targeting the interleukin-23-T helper 17 pathway has been developed. This study aimed to assess the short-term effectiveness and safety of these new agents using a network meta-analysis. Twenty-seven randomized clinical trials (10 629 patients) were identified by a comprehensive systematic literature review (PROSPERO 2015: CRD42015025472). Quality of evidence was assessed following Cochrane-compliant rules and the Grading of Recommendations, Assessment, Development and Evaluations approach. Efficacy and safety outcomes at weeks 10-16 were compared using a random-effects network meta-analysis within a frequentist framework to estimate pooled odds ratios (ORs) of direct and indirect comparisons among the therapeutic options. There were six direct drug-to-drug comparisons in the network, with a high degree of consistency between the direct and indirect evidence. From the available evidence, infliximab 5 mg kg -1 every 8 weeks [OR 118·89, 95% confidence interval (CI) 60·91-232·04] and secukinumab 300 mg every 4 weeks (OR 87·07, 95% CI 55·01-137·82) are shown to be among the most effective short-term treatments, but are ranked as the biologics most likely to produce any adverse event or an infectious adverse event, respectively. Ustekinumab 90 mg every 12 weeks, the third most efficacious treatment (OR 73·67, 95% CI 46·97-115·56), was the only agent that did not show increased risk of adverse events compared with placebo. Treatment recommendations should also consider long-term outcomes and costs. © 2016 British Association of Dermatologists.

Contact frequency and cognitive health among older adults in Israel.

PubMed

Schwartz, Ella; Khalaila, Rabia; Litwin, Howard

2018-05-03

The current study set out to examine the links between contact frequency with one's social network and cognitive health in later life. It assessed both direct and indirect pathways and the possible role of ethnicity in the effect of the social network on cognitive function. We used data from adults aged 50 and above, which was collected in Israel as part of the Survey of Ageing, Retirement and Health (SHARE). A moderated mediation analysis was conducted to test the direct and indirect associations between contact frequency and cognitive function, as well as the moderation of these associations by population group. Three population groups were examined - veteran-Jews, Arabs and immigrants from the former Soviet Union. Contact frequency with the close social milieu was found to be directly positively related to cognitive function. The association was also mediated by depressive symptoms, such that frequent contacts were linked to cognitive health via reduced depressive symptoms. This indirect link differed, however, among the three population groups. Contact frequency is important for cognitive health in the second half of life, and it operates both directly and by decreasing depressive symptoms. However, these links are not found among all ethnic groups and may, therefore, depend on the culture and social norms of each group and the meaning attributed to social ties.

A Novel Re-keying Function Protocol (NRFP) For Wireless Sensor Network Security.

PubMed

Abdullah, Maan Younis; Hua, Gui Wei; Alsharabi, Naif

2008-12-04

This paper describes a novel re-keying function protocol (NRFP) for wireless sensor network security. A re-keying process management system for sensor networks is designed to support in-network processing. The design of the protocol is motivated by decentralization key management for wireless sensor networks (WSNs), covering key deployment, key refreshment, and key establishment. NRFP supports the establishment of novel administrative functions for sensor nodes that derive/re-derive a session key for each communication session. The protocol proposes direct connection, in-direct connection and hybrid connection. NRFP also includes an efficient protocol for local broadcast authentication based on the use of one-way key chains. A salient feature of the authentication protocol is that it supports source authentication without precluding in-network processing. Security and performance analysis shows that it is very efficient in computation, communication and storage and, that NRFP is also effective in defending against many sophisticated attacks.

Advanced lesion symptom mapping analyses and implementation as BCBtoolkit

PubMed Central

Foulon, Chris; Cerliani, Leonardo; Kinkingnéhun, Serge; Levy, Richard; Rosso, Charlotte; Urbanski, Marika

2018-01-01

Abstract Background Patients with brain lesions provide a unique opportunity to understand the functioning of the human mind. However, even when focal, brain lesions have local and remote effects that impact functionally and structurally connected circuits. Similarly, function emerges from the interaction between brain areas rather than their sole activity. For instance, category fluency requires the associations between executive, semantic, and language production functions. Findings Here, we provide, for the first time, a set of complementary solutions for measuring the impact of a given lesion on the neuronal circuits. Our methods, which were applied to 37 patients with a focal frontal brain lesions, revealed a large set of directly and indirectly disconnected brain regions that had significantly impacted category fluency performance. The directly disconnected regions corresponded to areas that are classically considered as functionally engaged in verbal fluency and categorization tasks. These regions were also organized into larger directly and indirectly disconnected functional networks, including the left ventral fronto-parietal network, whose cortical thickness correlated with performance on category fluency. Conclusions The combination of structural and functional connectivity together with cortical thickness estimates reveal the remote effects of brain lesions, provide for the identification of the affected networks, and strengthen our understanding of their relationship with cognitive and behavioral measures. The methods presented are available and freely accessible in the BCBtoolkit as supplementary software [1]. PMID:29432527

Effects of contextual relevance on pragmatic inference during conversation: An fMRI study.

PubMed

Feng, Wangshu; Wu, Yue; Jan, Catherine; Yu, Hongbo; Jiang, Xiaoming; Zhou, Xiaolin

2017-08-01

Contextual relevance, which is vital for understanding conversational implicatures (CI), engages both the frontal-temporal language and theory-of-mind networks. Here we investigate how contextual relevance affects CI processing and regulates the connectivity between CI-processing-related brain regions. Participants listened to dialogues in which the level of contextual relevance to dialogue-final utterance (reply) was manipulated. This utterance was either direct, indirect but relevant, irrelevant with contextual hint, or irrelevant with no contextual hint. Results indicated that compared with direct replies, indirect replies showed increased activations in bilateral IFG, bilateral MTG, bilateral TPJ, dmPFC, and precuneus, and increased connectivity between rTPJ/dmPFC and both IFG and MTG. Moreover, irrelevant replies activated right MTG along an anterior-posterior gradient as a function of the level of irrelevance. Our study provides novel evidence concerning how the language and theory-of-mind networks interact for pragmatic inference and how the processing of CI is modulated by level of contextual relevance. Copyright © 2017 Elsevier Inc. All rights reserved.

School, Friends, and Substance Use: Gender Differences on the Influence of Attitudes Toward School and Close Friend Networks on Cannabis Involvement.

PubMed

Zaharakis, Nikola; Mason, Michael J; Mennis, Jeremy; Light, John; Rusby, Julie C; Westling, Erika; Crewe, Stephanie; Flay, Brian R; Way, Thomas

2018-02-01

The school environment is extremely salient in young adolescents' lives. Adolescents who have unfavorable attitudes toward school and teachers are at elevated risk for dropping out of school and engaging in behavioral health risks. Peer network health-a summation of the positive and negative behaviors in which one's close friend group engages-may be one way by which attitudes toward school exert influence on youth substance use. Utilizing a sample of 248 primarily African-American young urban adolescents, we tested a moderated mediation model to determine if the indirect effect of attitude to school on cannabis involvement through peer network health was conditioned on gender. Attitude toward school measured at baseline was the predictor (X), peer network health measured at 6 months was the mediator (M), cannabis involvement (including use, offers to use, and refusals to use) measured at 24 months was the outcome (Y), and gender was the moderator (W). Results indicated that negative attitudes toward school were indirectly associated with increased cannabis involvement through peer network health. This relationship was not moderated by gender. Adolescents in our sample with negative attitudes toward school were more likely to receive more offers to use cannabis and to use cannabis more frequently through the perceived health behaviors of their close friends. Implications from these results point to opportunities to leverage the dynamic associations among school experiences, friends, and cannabis involvement, such as offers and use.

Indirect iterative learning control for a discrete visual servo without a camera-robot model.

PubMed

Jiang, Ping; Bamforth, Leon C A; Feng, Zuren; Baruch, John E F; Chen, YangQuan

2007-08-01

This paper presents a discrete learning controller for vision-guided robot trajectory imitation with no prior knowledge of the camera-robot model. A teacher demonstrates a desired movement in front of a camera, and then, the robot is tasked to replay it by repetitive tracking. The imitation procedure is considered as a discrete tracking control problem in the image plane, with an unknown and time-varying image Jacobian matrix. Instead of updating the control signal directly, as is usually done in iterative learning control (ILC), a series of neural networks are used to approximate the unknown Jacobian matrix around every sample point in the demonstrated trajectory, and the time-varying weights of local neural networks are identified through repetitive tracking, i.e., indirect ILC. This makes repetitive segmented training possible, and a segmented training strategy is presented to retain the training trajectories solely within the effective region for neural network approximation. However, a singularity problem may occur if an unmodified neural-network-based Jacobian estimation is used to calculate the robot end-effector velocity. A new weight modification algorithm is proposed which ensures invertibility of the estimation, thus circumventing the problem. Stability is further discussed, and the relationship between the approximation capability of the neural network and the tracking accuracy is obtained. Simulations and experiments are carried out to illustrate the validity of the proposed controller for trajectory imitation of robot manipulators with unknown time-varying Jacobian matrices.

Cooperation enhanced by indirect reciprocity in spatial prisoner's dilemma games for social P2P systems

NASA Astrophysics Data System (ADS)

Tian, Lin-Lin; Li, Ming-Chu; Wang, Zhen

2016-11-01

With the growing interest in social Peer-to-Peer (P2P) applications, relationships of individuals are further exploited to improve the performances of reputation systems. It is an on-going challenge to investigate how spatial reciprocity aids indirect reciprocity in sustaining cooperation in practical P2P environments. This paper describes the construction of an extended prisoner's dilemma game on square lattice networks with three strategies, i.e., defection, unconditional cooperation, and reciprocal cooperation. Reciprocators discriminate partners according to their reputations based on image scoring, where mistakes in judgment of reputations may occur. The independent structures of interaction and learning neighborhood are discussed, with respect to the situation in which learning environments differ from interaction networks. The simulation results have indicated that the incentive mechanism enhances cooperation better in structured peers than among a well-mixed population. Given the realistic condition of inaccurate reputation scores, defection is still successfully held down when the players interact and learn within the unified neighborhoods. Extensive simulations have further confirmed the positive impact of spatial structure on cooperation with different sizes of lattice neighborhoods. And similar conclusions can also be drawn on regular random networks and scale-free networks. Moreover, for the separated structures of the neighborhoods, the interaction network has a critical effect on the evolution dynamics of cooperation and learning environments only have weaker impacts on the process. Our findings further provide some insights concerning the evolution of collective behaviors in social systems.

Networks of volatility spillovers among stock markets

NASA Astrophysics Data System (ADS)

Baumöhl, Eduard; Kočenda, Evžen; Lyócsa, Štefan; Výrost, Tomáš

2018-01-01

In our network analysis of 40 developed, emerging and frontier stock markets during the 2006-2014 period, we describe and model volatility spillovers during both the global financial crisis and tranquil periods. The resulting market interconnectedness is depicted by fitting a spatial model incorporating several exogenous characteristics. We document the presence of significant temporal proximity effects between markets and somewhat weaker temporal effects with regard to the US equity market - volatility spillovers decrease when markets are characterized by greater temporal proximity. Volatility spillovers also present a high degree of interconnectedness, which is measured by high spatial autocorrelation. This finding is confirmed by spatial regression models showing that indirect effects are much stronger than direct effects; i.e., market-related changes in 'neighboring' markets (within a network) affect volatility spillovers more than changes in the given market alone, suggesting that spatial effects simply cannot be ignored when modeling stock market relationships. Our results also link spillovers of escalating magnitude with increasing market size, market liquidity and economic openness.

Spatial-Temporal Dynamics of High-Resolution Animal Networks: What Can We Learn from Domestic Animals?

PubMed

Chen, Shi; Ilany, Amiyaal; White, Brad J; Sanderson, Michael W; Lanzas, Cristina

2015-01-01

Animal social network is the key to understand many ecological and epidemiological processes. We used real-time location system (RTLS) to accurately track cattle position, analyze their proximity networks, and tested the hypothesis of temporal stationarity and spatial homogeneity in these networks during different daily time periods and in different areas of the pen. The network structure was analyzed using global network characteristics (network density), subgroup clustering (modularity), triadic property (transitivity), and dyadic interactions (correlation coefficient from a quadratic assignment procedure) at hourly level. We demonstrated substantial spatial-temporal heterogeneity in these networks and potential link between indirect animal-environment contact and direct animal-animal contact. But such heterogeneity diminished if data were collected at lower spatial (aggregated at entire pen level) or temporal (aggregated at daily level) resolution. The network structure (described by the characteristics such as density, modularity, transitivity, etc.) also changed substantially at different time and locations. There were certain time (feeding) and location (hay) that the proximity network structures were more consistent based on the dyadic interaction analysis. These results reveal new insights for animal network structure and spatial-temporal dynamics, provide more accurate descriptions of animal social networks, and allow more accurate modeling of multiple (both direct and indirect) disease transmission pathways.

Social network media exposure and adolescent eating pathology in Fiji

PubMed Central

Becker, Anne E.; Fay, Kristen E.; Agnew-Blais, Jessica; Khan, A. Nisha; Striegel-Moore, Ruth H.; Gilman, Stephen E.

2011-01-01

Background Mass media exposure has been associated with an increased risk of eating pathology. It is unknown whether indirect media exposure – such as the proliferation of media exposure in an individual’s social network – is also associated with eating disorders. Aims To test hypotheses that both individual (direct) and social network (indirect) mass media exposures were associated with eating pathology in Fiji. Method We assessed several kinds of mass media exposure, media influence, cultural orientation and eating pathology by self-report among adolescent female ethnic Fijians (n = 523). We fitted a series of multiple regression models of eating pathology, assessed by the Eating Disorder Examination Questionnaire (EDE–Q), in which mass media exposures, sociodemographic characteristics and body mass index were entered as predictors. Results Both direct and indirect mass media exposures were associated with eating pathology in unadjusted analyses, whereas in adjusted analyses only social network media exposure was associated with eating pathology. This result was similar when eating pathology was operationalised as either a continuous or a categorical dependent variable (e.g. odds ratio OR = 1.60, 95% CI 1.15–2.23 relating social network media exposure to upper-quartile EDE–Q scores). Subsequent analyses pointed to individual media influence as an important explanatory variable in this association. Conclusions Social network media exposure was associated with eating pathology in this Fijian study sample, independent of direct media exposure and other cultural exposures. Findings warrant further investigation of its health impact in other populations. PMID:21200076

Social network media exposure and adolescent eating pathology in Fiji.

PubMed

Becker, Anne E; Fay, Kristen E; Agnew-Blais, Jessica; Khan, A Nisha; Striegel-Moore, Ruth H; Gilman, Stephen E

2011-01-01

Mass media exposure has been associated with an increased risk of eating pathology. It is unknown whether indirect media exposure--such as the proliferation of media exposure in an individual's social network--is also associated with eating disorders. To test hypotheses that both individual (direct) and social network (indirect) mass media exposures were associated with eating pathology in Fiji. We assessed several kinds of mass media exposure, media influence, cultural orientation and eating pathology by self-report among adolescent female ethnic Fijians (n=523). We fitted a series of multiple regression models of eating pathology, assessed by the Eating Disorder Examination Questionnaire (EDE-Q), in which mass media exposures, sociodemographic characteristics and body mass index were entered as predictors. Both direct and indirect mass media exposures were associated with eating pathology in unadjusted analyses, whereas in adjusted analyses only social network media exposure was associated with eating pathology. This result was similar when eating pathology was operationalised as either a continuous or a categorical dependent variable (e.g. odds ratio OR=1.60, 95% CI 1.15-2.23 relating social network media exposure to upper-quartile EDE-Q scores). Subsequent analyses pointed to individual media influence as an important explanatory variable in this association. Social network media exposure was associated with eating pathology in this Fijian study sample, independent of direct media exposure and other cultural exposures. Findings warrant further investigation of its health impact in other populations.

Incorporating food web dynamics into ecological restoration: a modeling approach for river ecosystems

Treesearch

J. Ryan Bellmore; Joseph R. Benjamin; Michael Newsom; Jennifer A. Bountry; Daniel Dombroski

2017-01-01

Restoration is frequently aimed at the recovery of target species, but also influences the larger food web in which these species participate. Effects of restoration on this broader network of organisms can influence target species both directly and indirectly via changes in energy flow through food webs. To help incorporate these complexities into river restoration...

The Relationship between Neighborhood Characteristics and Effective Parenting Behaviors: The Role of Social Support.

PubMed

Byrnes, Hilary F; Miller, Brenda A

2012-12-01

Neighborhood characteristics have been linked to healthy behavior, including effective parenting behaviors. This may be partially explained through the neighborhood's relation to parents' access to social support from friends and family. The current study examined associations of neighborhood characteristics with parenting behaviors indirectly through social support. The sample included 614 mothers of 11-12 year old youths enrolled in a health care system in the San Francisco area. Structural equations modeling shows that neighborhood perceptions were related to parenting behaviors, indirectly through social support, while archival census neighborhood indicators were unrelated to social support and parenting. Perceived neighborhood social cohesion and control were related to greater social support, which was related to more effective parenting style, parent-child communication, and monitoring. Perceived neighborhood disorganization was unrelated to social support. Prevention strategies should focus on helping parents build a social support network that can act as a resource in times of need.

Improving TWSTFT short-term stability by network time transfer.

PubMed

Tseng, Wen-Hung; Lin, Shinn-Yan; Feng, Kai-Ming; Fujieda, M; Maeno, H

2010-01-01

Two-way satellite time and frequency transfer (TWSTFT) is one of the major techniques to compare the atomic time scales between timing laboratories. As more and more TWSTFT measurements have been performed, the large number of point-to-point 2-way time transfer links has grown to be a complex network. For future improvement of the TWSTFT performance, it is important to reduce measurement noise of the TWSTFT results. One method is using TWSTFT network time transfer. The Asia-Pacific network is an exceptional case of simultaneous TWSTFT measurements. Some indirect links through relay stations show better shortterm stabilities than the direct link because the measurement noise may be neutralized in a simultaneous measurement network. In this paper, the authors propose a feasible method to improve the short-term stability by combining the direct and indirect links in the network. Through the comparisons of time deviation (TDEV), the results of network time transfer exhibit clear improved short-term stabilities. For the links used to compare 2 hydrogen masers, the average gain of TDEV at averaging times of 1 h is 22%. As TWSTFT short-term stability can be improved by network time transfer, the network may allow a larger number of simultaneously transmitting stations.

Interpersonal relationship quality mediates the association between military-related posttraumatic stress and academic dysfunction among student veterans.

PubMed

Fredman, Steffany J; Marshall, Amy D; Le, Yunying; Aronson, Keith R; Perkins, Daniel F; Hayes, Jeffrey A

2018-05-03

Large numbers of United States service members and veterans are enrolling in colleges and universities. Many are experiencing posttraumatic stress symptoms secondary to their military service, and these symptoms are associated with academic dysfunction. However, little is known about the mechanism(s) through which posttraumatic stress increases risk for academic difficulties. The goal of the current study was to evaluate perceived interpersonal relationship quality as a mediator of this association. The current study investigated the indirect effect of posttraumatic stress on academic dysfunction through three indices of perceived interpersonal relationship quality (i.e., family distress, family support, and social network support) in a clinical sample of 2,120 student service members and veterans. Participants were further divided into four groups based on relationship status and gender (i.e., partnered women, nonpartnered women, partnered men, and nonpartnered men), and moderation by group was examined. For all four groups, there were significant indirect effects of posttraumatic stress on academic dysfunction through greater family distress and lower social network support. Further, the overall indirect effect of posttraumatic stress on academic dysfunction was stronger for partnered women compared with the three other groups and was attributable to the stronger path from family distress to academic dysfunction for partnered women. Poor perceived relationship quality may be a modifiable risk factor for academic dysfunction among student service members and veterans experiencing military-related posttraumatic stress. Partnered women may be especially well-suited to interventions that enhance the interpersonal context of posttraumatic stress as a way to optimize academic outcomes. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Disentangling the co-structure of multilayer interaction networks: degree distribution and module composition in two-layer bipartite networks.

PubMed

Astegiano, Julia; Altermatt, Florian; Massol, François

2017-11-13

Species establish different interactions (e.g. antagonistic, mutualistic) with multiple species, forming multilayer ecological networks. Disentangling network co-structure in multilayer networks is crucial to predict how biodiversity loss may affect the persistence of multispecies assemblages. Existing methods to analyse multilayer networks often fail to consider network co-structure. We present a new method to evaluate the modular co-structure of multilayer networks through the assessment of species degree co-distribution and network module composition. We focus on modular structure because of its high prevalence among ecological networks. We apply our method to two Lepidoptera-plant networks, one describing caterpillar-plant herbivory interactions and one representing adult Lepidoptera nectaring on flowers, thereby possibly pollinating them. More than 50% of the species established either herbivory or visitation interactions, but not both. These species were over-represented among plants and lepidopterans, and were present in most modules in both networks. Similarity in module composition between networks was high but not different from random expectations. Our method clearly delineates the importance of interpreting multilayer module composition similarity in the light of the constraints imposed by network structure to predict the potential indirect effects of species loss through interconnected modular networks.

The Influence of Social Networks and Supports on Depression Symptoms: Differential Pathways for Older Korean Immigrants and Non-Hispanic White Americans.

PubMed

Jeon, Haesang; Lubben, James

The current cross-cultural study examines the pathways underlying different formations of social networks and social support systems, which affect depression symptoms among older Korean immigrants and non-Hispanic Whites in the United States. Data for this study came from a panel survey of 223 older Korean American immigrants and 201 non-Hispanic White older adults 65 years of age and older living in Los Angeles. Structural equation modeling (SEM) is used to test the proposed conceptual model designed to explain the direct and indirect relationships between social networks and social support on depression symptoms. Empirical evidence from this study indicated different effect of one's social networks and social support on depression by race/ethnicity. The work discussed in this article pointed to the need to recognize the role of culture in assessing the relationships between social networks, social support, and health among older adults.

A Novel Re-keying Function Protocol (NRFP) For Wireless Sensor Network Security

PubMed Central

Abdullah, Maan Younis; Hua, Gui Wei; Alsharabi, Naif

2008-01-01

This paper describes a novel re-keying function protocol (NRFP) for wireless sensor network security. A re-keying process management system for sensor networks is designed to support in-network processing. The design of the protocol is motivated by decentralization key management for wireless sensor networks (WSNs), covering key deployment, key refreshment, and key establishment. NRFP supports the establishment of novel administrative functions for sensor nodes that derive/re-derive a session key for each communication session. The protocol proposes direct connection, in-direct connection and hybrid connection. NRFP also includes an efficient protocol for local broadcast authentication based on the use of one-way key chains. A salient feature of the authentication protocol is that it supports source authentication without precluding innetwork processing. Security and performance analysis shows that it is very efficient in computation, communication and storage and, that NRFP is also effective in defending against many sophisticated attacks. PMID:27873963

Indirect Aggression, Bullying and Female Teen Victimization: A Literature Review

ERIC Educational Resources Information Center

Catanzaro, Mary F.

2011-01-01

This article assesses the literature in relation to youth bullying in the United Kingdom, Scandinavia and North America, focusing in particular on female aggression as it is expressed in adolescent peer relationships. It addresses the escalating problems of indirect aggression, especially those involving social networking interchanges such as…

Neural correlates of semantic associations in patients with schizophrenia.

PubMed

Sass, Katharina; Heim, Stefan; Sachs, Olga; Straube, Benjamin; Schneider, Frank; Habel, Ute; Kircher, Tilo

2014-03-01

Patients with schizophrenia have semantic processing disturbances leading to expressive language deficits (formal thought disorder). The underlying pathology has been related to alterations in the semantic network and its neural correlates. Moreover, crossmodal processing, an important aspect of communication, is impaired in schizophrenia. Here we investigated specific processing abnormalities in patients with schizophrenia with regard to modality and semantic distance in a semantic priming paradigm. Fourteen patients with schizophrenia and fourteen demographically matched controls made visual lexical decisions on successively presented word-pairs (SOA = 350 ms) with direct or indirect relations, unrelated word-pairs, and pseudoword-target stimuli during fMRI measurement. Stimuli were presented in a unimodal (visual) or crossmodal (auditory-visual) fashion. On the neural level, the effect of semantic relation indicated differences (patients > controls) within the right angular gyrus and precuneus. The effect of modality revealed differences (controls > patients) within the left superior frontal, middle temporal, inferior occipital, right angular gyri, and anterior cingulate cortex. Semantic distance (direct vs. indirect) induced distinct activations within the left middle temporal, fusiform gyrus, right precuneus, and thalamus with patients showing fewer differences between direct and indirect word-pairs. The results highlight aberrant priming-related brain responses in patients with schizophrenia. Enhanced activation for patients possibly reflects deficits in semantic processes that might be caused by a delayed and enhanced spread of activation within the semantic network. Modality-specific decreases of activation in patients might be related to impaired perceptual integration. Those deficits could induce and increase the prominent symptoms of schizophrenia like impaired speech processing.

Friend networking sites and their relationship to adolescents' well-being and social self-esteem.

PubMed

Valkenburg, Patti M; Peter, Jochen; Schouten, Alexander P

2006-10-01

The aim of this study was to investigate the consequences of friend networking sites (e.g., Friendster, MySpace) for adolescents' self-esteem and well-being. We conducted a survey among 881 adolescents (10-19-year-olds) who had an online profile on a Dutch friend networking site. Using structural equation modeling, we found that the frequency with which adolescents used the site had an indirect effect on their social self-esteem and well-being. The use of the friend networking site stimulated the number of relationships formed on the site, the frequency with which adolescents received feedback on their profiles, and the tone (i.e., positive vs. negative) of this feedback. Positive feedback on the profiles enhanced adolescents' social self-esteem and well-being, whereas negative feedback decreased their self-esteem and well-being.

Simulation of the radiolysis of water using Green's functions of the diffusion equation.

PubMed

Plante, I; Cucinotta, F A

2015-09-01

Radiation chemistry is of fundamental importance in the understanding of the effects of ionising radiation, notably with regard to DNA damage by indirect effect (e.g. damage by ·OH radicals created by the radiolysis of water). In the recent years, Green's functions of the diffusion equation (GFDEs) have been used extensively in biochemistry, notably to simulate biochemical networks in time and space. In the present work, an approach based on the GFDE will be used to refine existing models on the indirect effect of ionising radiation on DNA. As a starting point, the code RITRACKS (relativistic ion tracks) will be used to simulate the radiation track structure and calculate the position of all radiolytic species formed during irradiation. The chemical reactions between these radiolytic species and with DNA will be done by using an efficient Monte Carlo sampling algorithm for the GFDE of reversible reactions with an intermediate state that has been developed recently. These simulations should help the understanding of the contribution of the indirect effect in the formation of DNA damage, particularly with regards to the formation of double-strand breaks. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The Effects of Marital Support, Social Network Support, and Parenting Stress on Parenting: Self-Efficacy among Mothers of Young Children in Japan

ERIC Educational Resources Information Center

Suzuki, Sawako

2010-01-01

This study investigated whether Japanese women's perceived marital and social support affect their parenting self-efficacy directly or indirectly through their levels of parenting stress. Participants were 98 mothers of children in the second grade living in Sapporo or Osaka, Japan. Data collected through surveys were submitted to a structural…

An experimental analysis of granivory in a desert ecosystem: Progress report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, J.H.

1987-03-01

Controlled, replicated experiments are revealing the network of interactions that determine structure, dynamics, and energy transfer in a desert community that is functionally interconnected by the consumption of seeds (granivory). This community includes seed-eating rodents, ants, and birds, seed-producing annual and perennial plants, and other kinds of organisms that interact with these. The experiments entail removal of important species or functional groups of granivores or plants and supplementation of seed resources. The results demonstrate a large number of direct and indirect interactions that have important effects on the abundance of species and functional groups, the structure of the community, andmore » the dynamics of energy flow. The results suggest that networks of interaction are structured with sufficient overlap in resource requirements and interconnections through indirect pathways that community- and ecosystem-level processes, such as energy flow, are relatively insensitive to major perturbations in the abundance of particular species or functional groups. This preliminary finding has important implications for understanding the response of ecosystems to natural and human-caused perturbations, for the management of agricultural and other human-modified ecosystems, and for the design of perturbation-resistant networks for acquisition and distribution of human resources such energy and information. 44 refs.« less

Network meta-analysis combining individual patient and aggregate data from a mixture of study designs with an application to pulmonary arterial hypertension.

PubMed

Thom, Howard H Z; Capkun, Gorana; Cerulli, Annamaria; Nixon, Richard M; Howard, Luke S

2015-04-12

Network meta-analysis (NMA) is a methodology for indirectly comparing, and strengthening direct comparisons of two or more treatments for the management of disease by combining evidence from multiple studies. It is sometimes not possible to perform treatment comparisons as evidence networks restricted to randomized controlled trials (RCTs) may be disconnected. We propose a Bayesian NMA model that allows to include single-arm, before-and-after, observational studies to complete these disconnected networks. We illustrate the method with an indirect comparison of treatments for pulmonary arterial hypertension (PAH). Our method uses a random effects model for placebo improvements to include single-arm observational studies into a general NMA. Building on recent research for binary outcomes, we develop a covariate-adjusted continuous-outcome NMA model that combines individual patient data (IPD) and aggregate data from two-arm RCTs with the single-arm observational studies. We apply this model to a complex comparison of therapies for PAH combining IPD from a phase-III RCT of imatinib as add-on therapy for PAH and aggregate data from RCTs and single-arm observational studies, both identified by a systematic review. Through the inclusion of observational studies, our method allowed the comparison of imatinib as add-on therapy for PAH with other treatments. This comparison had not been previously possible due to the limited RCT evidence available. However, the credible intervals of our posterior estimates were wide so the overall results were inconclusive. The comparison should be treated as exploratory and should not be used to guide clinical practice. Our method for the inclusion of single-arm observational studies allows the performance of indirect comparisons that had previously not been possible due to incomplete networks composed solely of available RCTs. We also built on many recent innovations to enable researchers to use both aggregate data and IPD. This method could be used in similar situations where treatment comparisons have not been possible due to restrictions to RCT evidence and where a mixture of aggregate data and IPD are available.

Vulnerability analysis methods for road networks

NASA Astrophysics Data System (ADS)

Bíl, Michal; Vodák, Rostislav; Kubeček, Jan; Rebok, Tomáš; Svoboda, Tomáš

2014-05-01

Road networks rank among the most important lifelines of modern society. They can be damaged by either random or intentional events. Roads are also often affected by natural hazards, the impacts of which are both direct and indirect. Whereas direct impacts (e.g. roads damaged by a landslide or due to flooding) are localized in close proximity to the natural hazard occurrence, the indirect impacts can entail widespread service disabilities and considerable travel delays. The change in flows in the network may affect the population living far from the places originally impacted by the natural disaster. These effects are primarily possible due to the intrinsic nature of this system. The consequences and extent of the indirect costs also depend on the set of road links which were damaged, because the road links differ in terms of their importance. The more robust (interconnected) the road network is, the less time is usually needed to secure the serviceability of an area hit by a disaster. These kinds of networks also demonstrate a higher degree of resilience. Evaluating road network structures is therefore essential in any type of vulnerability and resilience analysis. There are a range of approaches used for evaluation of the vulnerability of a network and for identification of the weakest road links. Only few of them are, however, capable of simulating the impacts of the simultaneous closure of numerous links, which often occurs during a disaster. The primary problem is that in the case of a disaster, which usually has a large regional extent, the road network may remain disconnected. The majority of the commonly used indices use direct computation of the shortest paths or time between OD (origin - destination) pairs and therefore cannot be applied when the network breaks up into two or more components. Since extensive break-ups often occur in cases of major disasters, it is important to study the network vulnerability in these cases as well, so that appropriate steps can be taken in order to make it more resilient. Performing such an analysis of network break-ups requires consideration of the network as a whole, ideally identifying all the cases generated by simultaneous closure of multiple links and evaluating them using various criteria. The spatial distribution of settlements, important companies and the overall population in the nodes of the network are several factors, apart from the topology of the network which could be taken into account when computing vulnerability indices and identifying the weakest links and/or weakest link combinations. However, even for small networks (i.e., hundreds of nodes and links), the problem of break-up identification becomes extremely difficult to resolve. The naive approaches of the brute force examination consequently fail and more elaborated algorithms have to be applied. We address the problem of evaluating the vulnerability of road networks in our work by simulating the impacts of the simultaneous closure of multiple roads/links. We present an ongoing work on a sophisticated algorithm focused on the identification of network break-ups and evaluating them by various criteria.

Apparent competition drives community-wide parasitism rates and changes in host abundance across ecosystem boundaries

PubMed Central

Frost, Carol M.; Peralta, Guadalupe; Rand, Tatyana A.; Didham, Raphael K.; Varsani, Arvind; Tylianakis, Jason M.

2016-01-01

Species have strong indirect effects on others, and predicting these effects is a central challenge in ecology. Prey species sharing an enemy (predator or parasitoid) can be linked by apparent competition, but it is unknown whether this process is strong enough to be a community-wide structuring mechanism that could be used to predict future states of diverse food webs. Whether species abundances are spatially coupled by enemy movement across different habitats is also untested. Here, using a field experiment, we show that predicted apparent competitive effects between species, mediated via shared parasitoids, can significantly explain future parasitism rates and herbivore abundances. These predictions are successful even across edges between natural and managed forests, following experimental reduction of herbivore densities by aerial spraying of insecticide over 20 hectares. This result shows that trophic indirect effects propagate across networks and habitats in important, predictable ways, with implications for landscape planning, invasion biology and biological control. PMID:27577948

Social networks and health: a systematic review of sociocentric network studies in low- and middle-income countries.

PubMed

Perkins, Jessica M; Subramanian, S V; Christakis, Nicholas A

2015-01-01

In low- and middle-income countries (LMICs), naturally occurring social networks may be particularly vital to health outcomes as extended webs of social ties often are the principal source of various resources. Understanding how social network structure, and influential individuals within the network, may amplify the effects of interventions in LMICs, by creating, for example, cascade effects to non-targeted participants, presents an opportunity to improve the efficiency and effectiveness of public health interventions in such settings. We conducted a systematic review of PubMed, Econlit, Sociological Abstracts, and PsycINFO to identify a sample of 17 sociocentric network papers (arising from 10 studies) that specifically examined health issues in LMICs. We also separately selected to review 19 sociocentric network papers (arising from 10 other studies) on development topics related to wellbeing in LMICs. First, to provide a methodological resource, we discuss the sociocentric network study designs employed in the selected papers, and then provide a catalog of 105 name generator questions used to measure social ties across all the LMIC network papers (including both ego- and sociocentric network papers) cited in this review. Second, we show that network composition, individual network centrality, and network structure are associated with important health behaviors and health and development outcomes in different contexts across multiple levels of analysis and across distinct network types. Lastly, we highlight the opportunities for health researchers and practitioners in LMICs to 1) design effective studies and interventions in LMICs that account for the sociocentric network positions of certain individuals and overall network structure, 2) measure the spread of outcomes or intervention externalities, and 3) enhance the effectiveness and efficiency of aid based on knowledge of social structure. In summary, human health and wellbeing are connected through complex webs of dynamic social relationships. Harnessing such information may be especially important in contexts where resources are limited and people depend on their direct and indirect connections for support. Copyright © 2014 Elsevier Ltd. All rights reserved.

Social Networks and Health: A Systematic Review of Sociocentric Network Studies in Low- and Middle-Income Countries

PubMed Central

Perkins, Jessica M; Subramanian, S V; Christakis, Nicholas A

2015-01-01

In low- and middle-income countries (LMICs), naturally occurring social networks may be particularly vital to health outcomes as extended webs of social ties often are the principal source of various resources. Understanding how social network structure, and influential individuals within the network, may amplify the effects of interventions in LMICs, by creating, for example, cascade effects to non-targeted participants, presents an opportunity to improve the efficiency and effectiveness of public health interventions in such settings. We conducted a systematic review of PubMed, Econlit, Sociological Abstracts, and PsycINFO to identify a sample of 17 sociocentric network papers (arising from 10 studies) that specifically examined health issues in LMICs. We also separately selected to review 19 sociocentric network papers (arising from 10 other studies) on development topics related to wellbeing in LMICs. First, to provide a methodological resource, we discuss the sociocentric network study designs employed in the selected papers, and then provide a catalog of 105 name generator questions used to measure social ties across all the LMIC network papers (including both ego- and sociocentric network papers) cited in this review. Second, we show that network composition, individual network centrality, and network structure are associated with important health behaviors and health and development outcomes in different contexts across multiple levels of analysis and across distinct network types. Lastly, we highlight the opportunities for health researchers and practitioners in LMICs to 1) design effective studies and interventions in LMICs that account for the sociocentric network positions of certain individuals and overall network structure, 2) measure the spread of outcomes or intervention externalities, and 3) enhance the effectiveness and efficiency of aid based on knowledge of social structure. In summary, human health and wellbeing are connected through complex webs of dynamic social relationships. Harnessing such information may be especially important in contexts where resources are limited and people depend on their direct and indirect connections for support. PMID:25442969

Self-Reported and Network Scale-Up Estimates of Substance Use Prevalence among University Students in Kerman, Iran.

PubMed

Zahedi, Razieh; Noroozi, Alireza; Hajebi, Ahmad; Haghdoost, Ali Akbar; Baneshi, Mohammad Reza; Sharifi, Hamid; Mirzazadeh, Ali

2018-04-30

This study aimed to estimate the prevalence of substance use among university students measured by direct and indirect methods, and to calculate the visibility factor (VF) defined as ratio of indirect to direct estimates of substance use prevalence. A cross-sectional study. Using a multistage non-random sampling approach, we recruited 2157 students from three universities in Kerman, Iran, in 2016. We collected data on substance use by individual face-to-face interview using direct (i.e. self-report of their own behaviors) and indirect (NSU: Network scale up) methods. All estimates from direct and indirect methods were weighted based on inverse probability weight of sampling university. The response rate was 83.6%. The last year prevalence of water pipe, alcohol, and cigarettes indirect method was 44.6%, 18.1%, and 13.2% respectively. Corresponding figures in NSU analysis were 36.4%, 18.2%, and 16.5% respectively. In the female population, VF for all types of substance was less than male. Considerable numbers of university students used substances like a water pipe, alcohol, and cigarettes. NSU seems a promising method, especially among male students. Among female students, direct method provided more reliable results mainly due to transmission and prestige biases.

Efficacy, acceptability, and tolerability of antipsychotics in children and adolescents with schizophrenia: A network meta-analysis.

PubMed

Krause, Marc; Zhu, Yikang; Huhn, Maximilian; Schneider-Thoma, Johannes; Bighelli, Irene; Chaimani, Anna; Leucht, Stefan

2018-06-01

Children and adolescents with schizophrenia are a particularly vulnerable group. Thus, we integrated all the randomized evidence from the available antipsychotics used for this subgroup by performing a network-meta-analysis and pairwise meta-analysis using a random-effects model. We searched multiple databases up to Nov 17, 2016 (final update search in PubMed: Dec 12, 2017). The primary outcome was efficacy as measured by overall change/endpoint in symptoms of schizophrenia. Secondary outcomes included positive and negative symptoms, response, dropouts, quality of life, social functioning, weight gain, sedation, prolactin, extrapyramidal side effects (EPS) and antiparkinsonian medication. Twenty-eight randomized controlled trials (RCTs) with 3003 unique participants (58% males; mean age 14.41 years) published from 1967 to 2017 were identified. Clozapine was significantly more effective than all other analyzed antipsychotics. Nearly all antipsychotics were more efficacious compared to placebo, but ziprasidone showed no efficacy. In terms of preventing weight gain, molindone, lurasidone and ziprasidone were benign. The highest weight gain was found for clozapine, quetiapine and olanzapine. Most antipsychotics had some sedating effects. Risperidone, haloperidol, paliperidone and olanzapine were associated with prolactin increase. There were evidence gaps for some drugs and many outcomes, especially safety outcomes. Most of the comparisons are based only on one study or just on indirect evidence. Nevertheless, the available direct and indirect evidence showed that the treatment effects were similar compared to findings in adult patients with schizophrenia. Copyright © 2018 Elsevier B.V. and ECNP. All rights reserved.

Effective network inference through multivariate information transfer estimation

NASA Astrophysics Data System (ADS)

Dahlqvist, Carl-Henrik; Gnabo, Jean-Yves

2018-06-01

Network representation has steadily gained in popularity over the past decades. In many disciplines such as finance, genetics, neuroscience or human travel to cite a few, the network may not directly be observable and needs to be inferred from time-series data, leading to the issue of separating direct interactions between two entities forming the network from indirect interactions coming through its remaining part. Drawing on recent contributions proposing strategies to deal with this problem such as the so-called "global silencing" approach of Barzel and Barabasi or "network deconvolution" of Feizi et al. (2013), we propose a novel methodology to infer an effective network structure from multivariate conditional information transfers. Its core principal is to test the information transfer between two nodes through a step-wise approach by conditioning the transfer for each pair on a specific set of relevant nodes as identified by our algorithm from the rest of the network. The methodology is model free and can be applied to high-dimensional networks with both inter-lag and intra-lag relationships. It outperforms state-of-the-art approaches for eliminating the redundancies and more generally retrieving simulated artificial networks in our Monte-Carlo experiments. We apply the method to stock market data at different frequencies (15 min, 1 h, 1 day) to retrieve the network of US largest financial institutions and then document how bank's centrality measurements relate to bank's systemic vulnerability.

Species richness and soil properties in Pinus ponderosa forests: A structural equation modeling analysis

USGS Publications Warehouse

Laughlin, D.C.; Abella, S.R.; Covington, W.W.; Grace, J.B.

2007-01-01

Question: How are the effects of mineral soil properties on understory plant species richness propagated through a network of processes involving the forest overstory, soil organic matter, soil nitrogen, and understory plant abundance? Location: North-central Arizona, USA. Methods: We sampled 75 0.05-ha plots across a broad soil gradient in a Pinus ponderosa (ponderosa pine) forest ecosystem. We evaluated multivariate models of plant species richness using structural equation modeling. Results: Richness was highest at intermediate levels of understory plant cover, suggesting that both colonization success and competitive exclusion can limit richness in this system. We did not detect a reciprocal positive effect of richness on plant cover. Richness was strongly related to soil nitrogen in the model, with evidence for both a direct negative effect and an indirect non-linear relationship mediated through understory plant cover. Soil organic matter appeared to have a positive influence on understory richness that was independent of soil nitrogen. Richness was lowest where the forest overstory was densest, which can be explained through indirect effects on soil organic matter, soil nitrogen and understory cover. Finally, model results suggest a variety of direct and indirect processes whereby mineral soil properties can influence richness. Conclusions: Understory plant species richness and plant cover in P. ponderosa forests appear to be significantly influenced by soil organic matter and nitrogen, which are, in turn, related to overstory density and composition and mineral soil properties. Thus, soil properties can impose direct and indirect constraints on local species diversity in ponderosa pine forests. ?? IAVS; Opulus Press.

An Assessment of Direct and Indirect Economic Losses of Climatic Extreme Events

NASA Astrophysics Data System (ADS)

Otto, C.; Willner, S. N.; Wenz, L.; Levermann, A.

2015-12-01

Risk of extreme weather events like storms, heat extremes, and floods has already risen due to anthropogenic climate change and is likely to increase further under future global warming. Additionally, the structure of the global economy has changed importantly in the last decades. In the process of globalization, local economies have become more and more interwoven forming a complex network. Together with a trend towards lean production, this has resulted in a strong dependency of local manufacturers on global supply and value added chains, which may render the economic network more vulnerable to climatic extremes; outages of local manufacturers trigger indirect losses, which spread along supply chains and can even outstrip direct losses. Accordingly, in a comprehensive climate risk assessment these inter-linkages should be considered. Here, we present acclimate, an agent based dynamic damage propagation model. Its agents are production and consumption sites, which are interlinked by economic flows accounting for the complexity as well as the heterogeneity of the global supply network. Assessing the economic response on the timescale of the adverse event, the model permits to study temporal and spatial evolution of indirect production losses during the disaster and in the subsequent recovery phase of the economy. In this study, we focus on the dynamic economic resilience defined here as the ratio of direct to total losses. This implies that the resilience of the system under consideration is low if the high indirect losses are high. We find and assess a nonlinear dependence of the resilience on the disaster size. Further, we analyze the influence of the network structure upon resilience and discuss the potential of warehousing as an adaptation option.

Immediate memory consequences of the effect of emotion on attention to pictures.

PubMed

Talmi, Deborah; Anderson, Adam K; Riggs, Lily; Caplan, Jeremy B; Moscovitch, Morris

2008-03-01

Emotionally arousing stimuli are at once both highly attention grabbing and memorable. We examined whether emotional enhancement of memory (EEM) reflects an indirect effect of emotion on memory, mediated by enhanced attention to emotional items during encoding. We tested a critical prediction of the mediation hypothesis-that regions conjointly activated by emotion and attention would correlate with subsequent EEM. Participants were scanned with fMRI while they watched emotional or neutral pictures under instructions to attend to them a lot or a little, and were then given an immediate recognition test. A region in the left fusiform gyrus was activated by emotion, voluntary attention, and subsequent EEM. A functional network, different for each attention condition, connected this region and the amygdala, which was associated with emotion and EEM, but not with voluntary attention. These findings support an indirect cortical mediation account of immediate EEM that may complement a direct modulation model.

Immediate memory consequences of the effect of emotion on attention to pictures

PubMed Central

Talmi, Deborah; Anderson, Adam K.; Riggs, Lily; Caplan, Jeremy B.; Moscovitch, Morris

2008-01-01

Emotionally arousing stimuli are at once both highly attention grabbing and memorable. We examined whether emotional enhancement of memory (EEM) reflects an indirect effect of emotion on memory, mediated by enhanced attention to emotional items during encoding. We tested a critical prediction of the mediation hypothesis—that regions conjointly activated by emotion and attention would correlate with subsequent EEM. Participants were scanned with fMRI while they watched emotional or neutral pictures under instructions to attend to them a lot or a little, and were then given an immediate recognition test. A region in the left fusiform gyrus was activated by emotion, voluntary attention, and subsequent EEM. A functional network, different for each attention condition, connected this region and the amygdala, which was associated with emotion and EEM, but not with voluntary attention. These findings support an indirect cortical mediation account of immediate EEM that may complement a direct modulation model. PMID:18323572

Alveolar ridge preservation after tooth extraction: a Bayesian Network meta-analysis of grafting materials efficacy on prevention of bone height and width reduction.

PubMed

Iocca, Oreste; Farcomeni, Alessio; Pardiñas Lopez, Simon; Talib, Huzefa S

2017-01-01

To conduct a traditional meta-analysis and a Bayesian Network meta-analysis to synthesize the information coming from randomized controlled trials on different socket grafting materials and combine the resulting indirect evidence in order to make inferences on treatments that have not been compared directly. RCTs were identified for inclusion in the systematic review and subsequent statistical analysis. Bone height and width remodelling were selected as the chosen summary measures for comparison. First, a series of pairwise meta-analyses were performed and overall mean difference (MD) in mm with 95% CI was calculated between grafted versus non-grafted sockets. Then, a Bayesian Network meta-analysis was performed to draw indirect conclusions on which grafting materials can be considered most likely the best compared to the others. From the six included studies, seven comparisons were obtained. Traditional meta-analysis showed statistically significant results in favour of grafting the socket compared to no-graft both for height (MD 1.02, 95% CI 0.44-1.59, p value < 0.001) than for width (MD 1.52 95% CI 1.18-1.86, p value <0.000001) remodelling. Bayesian Network meta-analysis allowed to obtain a rank of intervention efficacy. On the basis of the results of the present analysis, socket grafting seems to be more favourable than unassisted socket healing. Moreover, Bayesian Network meta-analysis indicates that freeze-dried bone graft plus membrane is the most likely effective in the reduction of bone height remodelling. Autologous bone marrow resulted the most likely effective when width remodelling was considered. Studies with larger samples and less risk of bias should be conducted in the future in order to further strengthen the results of this analysis. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Tracking Effects of Problematic Social Networking on Adolescent Psychopathology: The Mediating Role of Sleep Disruptions.

PubMed

Vernon, Lynette; Modecki, Kathryn L; Barber, Bonnie L

2017-01-01

Concerns are growing about adolescents' problematic social networking and possible links to depressed mood and externalizing behavior. Yet there remains little understanding of underlying processes that may account for these associations, including the mediating role of sleep disruption. This study tests this putative mediating process and examines change in problematic social networking investment and disrupted sleep, in relation to change in depressed mood and externalizing behavior. A sample of 874 students (41% male; 57.2% Caucasian; baseline M age = 14.4 years) from 27 high schools were surveyed. Participants' problematic social networking, sleep disruption, and psychopathology (depressed mood, externalizing behaviors) were measured annually over 3 years. Longitudinal mediation was tested using latent trajectories of problematic social networking use, sleep disruption, and psychopathology. Both problematic social networking and sleep disruption underwent positive linear growth over time. Adolescents who increasingly invested in social networking reported increased depressed mood, with around 53% of this association explained by the indirect effect of increased sleep disruptions. Further, adolescents who increasingly invested in social networking also reported increased externalizing behavior; some of this relation was explained (13%) via increased sleep disruptions. However an alternative model in which increased externalizing was associated with increased social networking, mediated by sleep disruptions, indicated a reciprocal relation of similar magnitude. It is important for parents, teachers, and psychologists to minimize the negative effects of social networking on adolescents' psychopathology. Interventions should potentially target promoting healthy sleep habits through reductions in social networking investment and rescheduling usage away from bedtime.

Fighting Dark Networks: Using Social Network Analysis to Implement the Special Operations Targeting Process for Direct and Indirect Approaches

DTIC Science & Technology

2013-03-01

Wouter De Nooy, Andrej Mrvar and Vladimir Batagelj , Exploratory Social Network Analysis with Pajek, (New York: Cambridge University Press, 2005), 5...Granovetter, “The Strength of Weak Ties,” 1350–1368. 151 de Nooy, Mrvar , and Batagelj , Exploratory Social Network Analysis with Pajek, 151. 152...Spacetime Wrinkles Exhibit (1995). de Nooy, Wouter, Andrej Mrvar , and Vladimir Batagelj . Exploratory Social Network Analysis with Pajek. Cambridge

A network meta-analysis of randomized controlled trials for comparing the effectiveness and safety profile of treatments with marketing authorization for relapsing multiple sclerosis.

PubMed

Hadjigeorgiou, G M; Doxani, C; Miligkos, M; Ziakas, P; Bakalos, G; Papadimitriou, D; Mprotsis, T; Grigoriadis, N; Zintzaras, E

2013-12-01

The relative effectiveness and safety profile of the treatments with marketing authorization for relapsing multiple sclerosis (MS) are not well known because randomized controlled trials with head-to-head comparisons between these treatments do not exist. Thus, a network of multiple-treatments meta-analysis was performed using four clinical outcomes: 'patients free of relapse', 'patients without disease progression', 'patients without MRI progression' and 'patients with adverse events'. Randomized controlled trials (RCTs) on MS were systematically searched in PubMed and Cochrane Central Register of Controlled Trial. The network analysis performed pairwise comparisons between the marketed treatments (Betaferon 250mcg, Avonex 30mcg, Rebif 44mcg, Rebif 22mcg, Aubagio 7 mg, Aubagio 14 mg, Copaxone 20 mg, Tysabri 300 mg, Gilenya 0·5 mg and Novantrone 12 mg/m(2)) using direct and indirect analyses. The analysis included 48 articles, involving 20 455 patients with MS. The direct analysis showed better response for more than one outcome for Gilenya compared with Avonex ('patients free of relapse' and 'patients without MRI progression') and for Betaferon compared with Avonex ('patients without disease progression' and 'patients without MRI progression'). The indirect analysis indicated that Tysabri may have better relative effectiveness compared with the other treatments for two outcomes: 'patients free of relapse' and 'patients without MRI progression'. Regarding 'patients with adverse events', no data were available for all comparisons to make fair inferences. This was an attempt, for the first time, to compare the efficacy and safety profile of existing approved treatments for relapsing MS. Although some treatments have shown better response, the results of the network analysis should be interpreted with caution because of the lack of RCTs with head-to-head comparisons between treatments. © 2013 John Wiley & Sons Ltd.

Direct and indirect effects of caregiver social support on adolescent psychological outcomes in two South African AIDS-affected communities

PubMed Central

Casale, Marisa; Cluver, Lucie; Crankshaw, Tamaryn; Kuo, Caroline; Lachman, Jamie M.; Wild, Lauren G.

2015-01-01

Caregiver social support has been shown to be protective for caregiver mental health, parenting and child psychosocial outcomes. This is the first known analysis to quantitatively investigate the relationship between caregiver social support and adolescent psychosocial outcomes in HIV-endemic, resource-scarce Southern African communities. A cross-sectional household survey was conducted over 2009-2010 with 2477 South African adolescents aged 10-17 and their adult caregivers (18 years or older) in one urban and one rural community in South Africa’s KwaZulu-Natal province. Adolescent adjustment was assessed using adult caregiver reports of the Strengths and Difficulties questionnaire (SDQ), which measures peer problems, hyperactivity, conduct problems, emotional symptoms and child prosocial behavior. Hierarchical linear regressions and multiple mediation analyses, using bootstrapping procedures, were conducted to assess for: a) direct effects of more caregiver social support on better adolescent psychosocial wellbeing; and b) indirect effects mediated by better parenting and caregiver mental health. Direct associations (p<.001), and indirect associations mediated through better parenting, were found for all adolescent outcomes. Findings reinforce the importance of social support components within parenting interventions but also point to scope for positive intervention on adolescent psychosocial wellbeing through the broader family social network. PMID:25623784

Diversity Increases Indirect Interactions, Attenuates the Intensity of Competition, and Promotes Coexistence.

PubMed

Aschehoug, Erik T; Callaway, Ragan M

2015-10-01

A fundamental assumption of coexistence theory is that competition inevitably decreases species diversity. Consequently, in the quest to understand the ecological regulators of diversity, there has been a great deal of focus on processes with the potential to reduce competitive exclusion. However, the notion that competition must decrease diversity is largely based on the outcome of two-species interaction experiments and models, despite the fact that species rarely interact only in pairs in natural systems. In a field experiment, we found that competition among native perennial plants in multispecies assemblages was far weaker than competition between those same species in pairwise arrangements and that indirect interactions appeared to weaken direct competitive effects. These results suggest that community assembly theory based on pairwise approaches may overestimate the strength of competition and likelihood of competitive exclusion in species-rich communities. We also found that Centaurea stoebe, a North American invader, retained strong competitive effects when competing against North American natives in both pairwise and multispecies assemblages. Our experimental results support an emerging body of theory suggesting that complex networks of competing species may generate strong indirect interactions that can maintain diversity and that ecological differentiation may not be necessary to attenuate competition.

Genome-wide protein-protein interactions and protein function exploration in cyanobacteria

PubMed Central

Lv, Qi; Ma, Weimin; Liu, Hui; Li, Jiang; Wang, Huan; Lu, Fang; Zhao, Chen; Shi, Tieliu

2015-01-01

Genome-wide network analysis is well implemented to study proteins of unknown function. Here, we effectively explored protein functions and the biological mechanism based on inferred high confident protein-protein interaction (PPI) network in cyanobacteria. We integrated data from seven different sources and predicted 1,997 PPIs, which were evaluated by experiments in molecular mechanism, text mining of literatures in proved direct/indirect evidences, and “interologs” in conservation. Combined the predicted PPIs with known PPIs, we obtained 4,715 no-redundant PPIs (involving 3,231 proteins covering over 90% of genome) to generate the PPI network. Based on the PPI network, terms in Gene ontology (GO) were assigned to function-unknown proteins. Functional modules were identified by dissecting the PPI network into sub-networks and analyzing pathway enrichment, with which we investigated novel function of underlying proteins in protein complexes and pathways. Examples of photosynthesis and DNA repair indicate that the network approach is a powerful tool in protein function analysis. Overall, this systems biology approach provides a new insight into posterior functional analysis of PPIs in cyanobacteria. PMID:26490033

Pattern Learning, Damage and Repair within Biological Neural Networks

NASA Astrophysics Data System (ADS)

Siu, Theodore; Fitzgerald O'Neill, Kate; Shinbrot, Troy

2015-03-01

Traumatic brain injury (TBI) causes damage to neural networks, potentially leading to disability or even death. Nearly one in ten of these patients die, and most of the remainder suffer from symptoms ranging from headaches and nausea to convulsions and paralysis. In vitro studies to develop treatments for TBI have limited in vivo applicability, and in vitro therapies have even proven to worsen the outcome of TBI patients. We propose that this disconnect between in vitro and in vivo outcomes may be associated with the fact that in vitro tests assess indirect measures of neuronal health, but do not investigate the actual function of neuronal networks. Therefore in this talk, we examine both in vitro and in silico neuronal networks that actually perform a function: pattern identification. We allow the networks to execute genetic, Hebbian, learning, and additionally, we examine the effects of damage and subsequent repair within our networks. We show that the length of repaired connections affects the overall pattern learning performance of the network and we propose therapies that may improve function following TBI in clinical settings.

Injection Drug Users’ Involvement In Drug Economy: Dynamics of Sociometric and Egocentric Social Networks

PubMed Central

Yang, Cui; Latkin, Carl; Muth, Stephen Q.; Rudolph, Abby

2014-01-01

The purpose of this analysis was to examine the effect of social network cohesiveness on drug economy involvement, and to test whether this relationship is mediated by drug support network size in a sample of active injection drug users. Involvement in the drug economy was defined by self-report of participation in at least one of the following activities: selling drugs, holding drugs or money for drugs, providing street security for drug sellers, cutting/packaging/cooking drugs, selling or renting drug paraphernalia (e.g., pipes, tools, rigs), and injecting drugs in others’ veins. The sample consists of 273 active injection drug users in Baltimore, Maryland who reported having injected drugs in the last 6 months and were recruited through either street outreach or by their network members. Egocentric drug support networks were assessed through a social network inventory at baseline. Sociometric networks were built upon the linkages by selected matching characteristics, and k-plex rank was used to characterize the level of cohesiveness of the individual to others in the social network. Although no direct effect was observed, structural equation modeling indicated k-plex rank was indirectly associated with drug economy involvement through drug support network size. These findings suggest the effects of large-scale sociometric networks on injectors’ drug economy involvement may occur through their immediate egocentric networks. Future harm reduction programs for injection drug users (IDUs) should consider providing programs coupled with economic opportunities to those drug users within a cohesive network subgroup. Moreover, individuals with a high connectivity to others in their network may be optimal individuals to train for diffusing HIV prevention messages. PMID:25309015

Comparative thoracic anatomy of the wild type and wingless (wg1cn1) mutant of Drosophila melanogaster (Diptera).

PubMed

Fabian, Benjamin; Schneeberg, Katharina; Beutel, Rolf Georg

2016-11-01

Genetically modified organisms are crucial for our understanding of gene regulatory networks, physiological processes and ontogeny. With modern molecular genetic techniques allowing the rapid generation of different Drosophila melanogaster mutants, efficient in-depth morphological investigations become an important issue. Anatomical studies can elucidate the role of certain genes in developmental processes and point out which parts of gene regulatory networks are involved in evolutionary changes of morphological structures. The wingless mutation wg 1 of D. melanogaster was discovered more than 40 years ago. While early studies addressed the external phenotype of these mutants, the documentation of the internal organization was largely restricted to the prominent indirect flight muscles. We used SEM micrographs, histological serial sections, μ-computed tomography, CLSM and 3D reconstructions to study and document the thoracic skeletomuscular system of the wild type and mutant. A recently introduced nomenclature for the musculature of neopteran insects was applied to facilitate comparisons with closely or more distantly related taxa. The mutation is phenotypically mainly characterized by the absence of one or both wings and halteres. The wing is partly or entirely replaced by duplications of mesonotal structures, whereas the haltere and its associated muscles are completely absent on body sides showing the reduction. Both the direct and indirect mesothoracic flight muscles are affected by loss and reorientation of bundles or fibers. Our observations lead to the conclusion that the wingless mutation causes a homeotic transformation in the imaginal discs of wings and halteres with a direct effect on the development of skeletal structures and an indirect effect on the associated muscular system. Copyright © 2016 Elsevier Ltd. All rights reserved.

Indirect Treatment Comparison of Talimogene Laherparepvec Compared with Ipilimumab and Vemurafenib for the Treatment of Patients with Metastatic Melanoma.

PubMed

Quinn, Casey; Ma, Qiufei; Kudlac, Amber; Palmer, Stephen; Barber, Beth; Zhao, Zhongyun

2016-04-01

Few randomized controlled trials have compared new treatments for metastatic melanoma. We sought to examine the relative treatment effect of talimogene laherparepvec compared with ipilimumab and vemurafenib. A systematic literature review of treatments for metastatic melanoma was undertaken but a valid network of evidence could not be established because of a lack of comparative data or studies with sufficient common comparators. A conventional adjusted indirect treatment comparison via network meta-analysis was, therefore, not feasible. Instead, a meta-analysis of absolute efficacy was undertaken, adjusting overall survival (OS) data for differences in prognostic factors between studies using a published algorithm. Four trials were included in the final indirect treatment comparison: two of ipilimumab, one of vemurafenib, and one of talimogene laherparepvec. Median OS for ipilimumab and vemurafenib increased significantly when adjustment was applied, demonstrating that variation in disease and patient characteristics was biasing OS estimates; adjusting for this made the survival data more comparable. For both ipilimumab and vemurafenib, the adjustments improved Kaplan-Meier OS curves; the observed talimogene laherparepvec OS curve remained above the adjusted OS curves for ipilimumab and vemurafenib, showing that long-term survival could differ from the observed medians. Even with limited data, talimogene laherparepvec, ipilimumab, and vemurafenib could be compared following adjustments, thereby providing a more reliable understanding of the relative effect of treatment on survival in a more comparable patient population. The results of this analysis suggest that OS with talimogene laherparepvec is at least as good as with ipilimumab and vemurafenib and improvement was more pronounced in patients with no bone, brain, lung or other visceral metastases. Amgen Inc.

The Relationship between Neighborhood Characteristics and Effective Parenting Behaviors: The Role of Social Support

PubMed Central

Byrnes, Hilary F.; Miller, Brenda A.

2011-01-01

Neighborhood characteristics have been linked to healthy behavior, including effective parenting behaviors. This may be partially explained through the neighborhood’s relation to parents’ access to social support from friends and family. The current study examined associations of neighborhood characteristics with parenting behaviors indirectly through social support. The sample included 614 mothers of 11–12 year old youths enrolled in a health care system in the San Francisco area. Structural equations modeling shows that neighborhood perceptions were related to parenting behaviors, indirectly through social support, while archival census neighborhood indicators were unrelated to social support and parenting. Perceived neighborhood social cohesion and control were related to greater social support, which was related to more effective parenting style, parent-child communication, and monitoring. Perceived neighborhood disorganization was unrelated to social support. Prevention strategies should focus on helping parents build a social support network that can act as a resource in times of need. PMID:23794774

Mapping higher-order relations between brain structure and function with embedded vector representations of connectomes.

PubMed

Rosenthal, Gideon; Váša, František; Griffa, Alessandra; Hagmann, Patric; Amico, Enrico; Goñi, Joaquín; Avidan, Galia; Sporns, Olaf

2018-06-05

Connectomics generates comprehensive maps of brain networks, represented as nodes and their pairwise connections. The functional roles of nodes are defined by their direct and indirect connectivity with the rest of the network. However, the network context is not directly accessible at the level of individual nodes. Similar problems in language processing have been addressed with algorithms such as word2vec that create embeddings of words and their relations in a meaningful low-dimensional vector space. Here we apply this approach to create embedded vector representations of brain networks or connectome embeddings (CE). CE can characterize correspondence relations among brain regions, and can be used to infer links that are lacking from the original structural diffusion imaging, e.g., inter-hemispheric homotopic connections. Moreover, we construct predictive deep models of functional and structural connectivity, and simulate network-wide lesion effects using the face processing system as our application domain. We suggest that CE offers a novel approach to revealing relations between connectome structure and function.

Neighborhoods and Adolescent Health-Risk Behavior: An Ecological Network Approach1

PubMed Central

Browning, Christopher R.; Soller, Brian; Jackson, Aubrey L.

2014-01-01

This study integrates insights from social network analysis, activity space perspectives, and theories of urban and spatial processes to present an innovative approach to neighborhood effects on health-risk behavior among youth. We suggest spatial patterns of neighborhood residents’ non-home routine activities may be conceptualized as ecological, or “eco”-networks, which are two-mode networks that indirectly link residents through socio-spatial overlap in routine activities. We further argue structural configurations of eco-networks are consequential for youth’s behavioral health. In this study we focus on a key structural feature of eco-networks—the neighborhood-level extent to which households share two or more activity locations, or eco-network reinforcement—and its association with two dimensions of health-risk behavior, substance use and delinquency/sexual activity. Using geographic data on non-home routine activity locations among respondents from the Los Angeles Family and Neighborhood Survey (L.A.FANS), we constructed neighborhood-specific eco-networks by connecting sampled households to “activity clusters,” which are sets of spatially-proximate activity locations. We then measured eco-network reinforcement and examined its association with adolescent dimensions of health risk behavior employing a sample of 830 youth ages 12-17 nested in 65 census tracts. We also examined whether neighborhood-level social processes (collective efficacy and intergenerational closure) mediate the association between eco-network reinforcement and the outcomes considered. Results indicated eco-network reinforcement exhibits robust negative associations with both substance use and delinquency/sexual activity scales. Eco-network reinforcement effects were not explained by potential mediating variables. In addition to introducing a novel theoretical and empirical approach to neighborhood effects on youth, our findings highlight the importance of eco-network reinforcement for adolescent behavioral health. PMID:25011958

Aggression Norms in the Classroom Social Network: Contexts of Aggressive Behavior and Social Preference in Middle Childhood.

PubMed

Jackson, Daisy R; Cappella, Elise; Neal, Jennifer Watling

2015-12-01

In a cross-sectional sample of African-American 2nd-4th grade students (N = 681), we examine the moderating effects of classroom overt and relational aggression norms on peers' social acceptance of classmates who exhibit overt and relational aggression in urban schools. Extending theory and research on classroom norms, we integrate social network data to adjust aggression norms based on children's direct and indirect connections in the classroom. Results of multilevel models indicate that network-based classroom aggression norms moderated relations between children's aggressive behavior and their social preference. Specifically, children benefited socially when their form of aggressive behavior fit with what was normative in the classroom social context. The moderating effect of classroom aggression norms was stronger for the association between overt aggression and social preference than relational aggression and social preference. Relationally aggressive youth were socially preferred by peers regardless of the classroom norm, although this positive association was magnified in classrooms with higher levels of relational aggression. Future research focused on aggression norms within classroom social networks are discussed and implications for school prevention efforts are considered.

Predicting community responses to perturbations in the face of imperfect knowledge and network complexity

USGS Publications Warehouse

Novak, Mark; Wootton, J. Timothy; Doak, Daniel F.; Emmerson, Mark; Estes, James A.; Tinker, M. Timothy

2011-01-01

How best to predict the effects of perturbations to ecological communities has been a long-standing goal for both applied and basic ecology. This quest has recently been revived by new empirical data, new analysis methods, and increased computing speed, with the promise that ecologically important insights may be obtainable from a limited knowledge of community interactions. We use empirically based and simulated networks of varying size and connectance to assess two limitations to predicting perturbation responses in multispecies communities: (1) the inaccuracy by which species interaction strengths are empirically quantified and (2) the indeterminacy of species responses due to indirect effects associated with network size and structure. We find that even modest levels of species richness and connectance (∼25 pairwise interactions) impose high requirements for interaction strength estimates because system indeterminacy rapidly overwhelms predictive insights. Nevertheless, even poorly estimated interaction strengths provide greater average predictive certainty than an approach that uses only the sign of each interaction. Our simulations provide guidance in dealing with the trade-offs involved in maximizing the utility of network approaches for predicting dynamics in multispecies communities.

Posttraumatic stress disorder symptoms and attitudes about social support: Does shame matter?

PubMed

Dodson, Thomas S; Beck, J Gayle

2017-04-01

Considerable research has examined the association between posttraumatic stress disorder (PTSD) symptoms and social support. One facet of this relationship that deserves greater attention concerns trauma survivors' negative expectations towards social support, termed negative network orientation. To expand our understanding of negative network orientation, the current study examined shame as a possible mediator in the relationship between PTSD symptoms and negative network orientation, in a sample of 202 female survivors of intimate partner violence (IPV). Additionally, a history of child abuse (CA) was evaluated as a moderator of the association between shame and negative network orientation in this model. Path analyses indicated a significant indirect effect between PTSD symptoms and negative network orientation through shame, indicative of mediation. A history of CA moderated this effect, such that women with a history of CA in addition to IPV showed a significantly stronger relationship between PTSD symptoms and negative network orientation through shame, relative to women who only had a history of IPV. These findings support the relevance of shame in understanding the association between PTSD symptoms and negative beliefs about social support and highlight the role of childhood abuse as a moderator in this process among IPV survivors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Indirect exposure to a family planning mass media campaign in Nepal.

PubMed

Boulay, Marc; Storey, J Douglas; Sood, Suruchi

2002-01-01

It is often noted that some individuals become aware of a mass media program's messages through discussions with other individuals. However, the extent to which indirect exposure occurs, and its influence on behavior, are somewhat unclear. This study examines the role of indirect exposure in extending the reach of a family planning mass media campaign in Nepal. Sociometric data, gathered from nearly all women between the ages of 15 and 49 years living in six villages in Dang District, Nepal (N = 667), assessed indirect exposure to the radio program. Indirect exposure was extensive; half of all respondents were indirectly exposed to the program's messages and the overall reach of the program increased from 50% to 75% when indirect exposure was considered. Members of community groups had higher levels of direct exposure to the radio program and more extensive and diverse social networks, allowing them to serve as a conduit for these messages into the wider community. While direct exposure to the radio program appeared to influence family planning knowledge, indirect exposure was more strongly associated with contraceptive use. These findings suggest that program evaluations that ignore indirect exposure underestimate the impact of a mass media program on behavior.

In silico Evolutionary Developmental Neurobiology and the Origin of Natural Language

NASA Astrophysics Data System (ADS)

Szathmáry, Eörs; Szathmáry, Zoltán; Ittzés, Péter; Orbaán, Geroő; Zachár, István; Huszár, Ferenc; Fedor, Anna; Varga, Máté; Számadó, Szabolcs

It is justified to assume that part of our genetic endowment contributes to our language skills, yet it is impossible to tell at this moment exactly how genes affect the language faculty. We complement experimental biological studies by an in silico approach in that we simulate the evolution of neuronal networks under selection for language-related skills. At the heart of this project is the Evolutionary Neurogenetic Algorithm (ENGA) that is deliberately biomimetic. The design of the system was inspired by important biological phenomena such as brain ontogenesis, neuron morphologies, and indirect genetic encoding. Neuronal networks were selected and were allowed to reproduce as a function of their performance in the given task. The selected neuronal networks in all scenarios were able to solve the communication problem they had to face. The most striking feature of the model is that it works with highly indirect genetic encoding--just as brains do.

Does Physical Activity Mediate the Associations Between Local-Area Descriptive Norms, Built Environment Walkability, and Glycosylated Hemoglobin?

PubMed

Carroll, Suzanne J; Niyonsenga, Theo; Coffee, Neil T; Taylor, Anne W; Daniel, Mark

2017-08-23

Associations between local-area residential features and glycosylated hemoglobin (HbA 1c ) may be mediated by individual-level health behaviors. Such indirect effects have rarely been tested. This study assessed whether individual-level self-reported physical activity mediated the influence of local-area descriptive norms and objectively expressed walkability on 10-year change in HbA 1c . HbA 1c was assessed three times for adults in a 10-year population-based biomedical cohort ( n = 4056). Local-area norms specific to each participant were calculated, aggregating responses from a separate statewide surveillance survey for 1600 m road-network buffers centered on participant addresses (local prevalence of overweight/obesity (body mass index ≥25 kg/m²) and physical inactivity (<150 min/week)). Separate latent growth models estimated direct and indirect (through physical activity) effects of local-area exposures on change in HbA 1c , accounting for spatial clustering and covariates (individual-level age, sex, smoking status, marital status, employment and education, and area-level median household income). HbA 1c worsened over time. Local-area norms directly and indirectly predicted worsening HbA 1c trajectories. Walkability was directly and indirectly protective of worsening HbA 1c . Local-area descriptive norms and walkability influence cardiometabolic risk trajectory through individual-level physical activity. Efforts to reduce population cardiometabolic risk should consider the extent of local-area unhealthful behavioral norms and walkability in tailoring strategies to improve physical activity.

Does Physical Activity Mediate the Associations between Local-Area Descriptive Norms, Built Environment Walkability, and Glycosylated Hemoglobin?

PubMed Central

Daniel, Mark

2017-01-01

Associations between local-area residential features and glycosylated hemoglobin (HbA1c) may be mediated by individual-level health behaviors. Such indirect effects have rarely been tested. This study assessed whether individual-level self-reported physical activity mediated the influence of local-area descriptive norms and objectively expressed walkability on 10-year change in HbA1c. HbA1c was assessed three times for adults in a 10-year population-based biomedical cohort (n = 4056). Local-area norms specific to each participant were calculated, aggregating responses from a separate statewide surveillance survey for 1600 m road-network buffers centered on participant addresses (local prevalence of overweight/obesity (body mass index ≥25 kg/m2) and physical inactivity (<150 min/week)). Separate latent growth models estimated direct and indirect (through physical activity) effects of local-area exposures on change in HbA1c, accounting for spatial clustering and covariates (individual-level age, sex, smoking status, marital status, employment and education, and area-level median household income). HbA1c worsened over time. Local-area norms directly and indirectly predicted worsening HbA1c trajectories. Walkability was directly and indirectly protective of worsening HbA1c. Local-area descriptive norms and walkability influence cardiometabolic risk trajectory through individual-level physical activity. Efforts to reduce population cardiometabolic risk should consider the extent of local-area unhealthful behavioral norms and walkability in tailoring strategies to improve physical activity. PMID:28832552

Cultural congruence with psychotherapy efficacy: A network meta-analytic examination in China.

PubMed

Xu, Hui; Tracey, Terence J G

2016-04-01

We used network meta-analysis to examine the relative efficacy of 3 treatment modalities in China (i.e., cognitive-psychoeducational therapy, humanistic-experiential therapy, and indigenous therapy) on the basis of a comprehensive review of randomized control trials (n = 235). The cultural congruence hypothesis derived from the contextual model argues that psychotherapy efficacy varies by the extent to which therapy modalities match the cultural context in its description of pathology and healing modalities. Given the experiential-subjective emphasis of Chinese culture, we proposed indigenous therapy and humanistic-experiential therapy being more effective than cognitive-psychoeducational therapy. Results based on indirect and direct comparisons supported the hypothesized differences in effectiveness. Treatments that more closely matched Chinese understandings of pathology and change experience were more effective. The practical and theoretical implications of the present study were discussed along with limitations. (c) 2016 APA, all rights reserved).

Network features of sector indexes spillover effects in China: A multi-scale view

NASA Astrophysics Data System (ADS)

Feng, Sida; Huang, Shupei; Qi, Yabin; Liu, Xueyong; Sun, Qingru; Wen, Shaobo

2018-04-01

The spillover effects among sectors are of concern for distinct market participants, who are in distinct investment horizons and concerned with the information in different time scales. In order to uncover the hidden spillover information in multi-time scales in the rapidly changing stock market and thereby offer guidance to different investors concerning distinct time scales from a system perspective, this paper constructed directional spillover effect networks for the economic sectors in distinct time scales. The results are as follows: (1) The "2-4 days" scale is the most risky scale, and the "8-16 days" scale is the least risky one. (2) The most influential and sensitive sectors are distinct in different time scales. (3) Although two sectors in the same community may not have direct spillover relations, the volatility of one sector will have a relatively strong influence on the other through indirect relations.

The relationships among family, friends, and psychological well-being for Thai elderly.

PubMed

Thanakwang, Kattika; Ingersoll-Dayton, Berit; Soonthorndhada, Kusol

2012-01-01

The extent to which family and friends contribute to psychological well-being (PWB) may be subject to cultural variability. This study examines the mechanisms by which relationships with family and friends contribute to PWB among Thai elders. Interviews were conducted with 469 men and women aged 60 and older in Nan Province, Thailand. The data were analyzed using structural equation modeling, controlling for age, gender, education, income, marital status, and health status. Family and friendship networks have a significant direct effect on family and friendship support. However, family and friendship networks do not have a significant direct effect on PWB, but rather an indirect effect via social support. Similarly, friendship support mediates the relationship between friendship networks and family support. Both family support and friendship support are significantly related to PWB but family support is the stronger predictor. Using an adapting theoretical framework developed by Berkman, Glass, Brissette, & Seeman (2000) allows researchers to map the various pathways by which relationships with family and friends may contribute to PWB among older Thai adults.

Modeling Endoplasmic Reticulum Network Maintenance in a Plant Cell.

PubMed

Lin, Congping; White, Rhiannon R; Sparkes, Imogen; Ashwin, Peter

2017-07-11

The endoplasmic reticulum (ER) in plant cells forms a highly dynamic network of complex geometry. ER network morphology and dynamics are influenced by a number of biophysical processes, including filament/tubule tension, viscous forces, Brownian diffusion, and interactions with many other organelles and cytoskeletal elements. Previous studies have indicated that ER networks can be thought of as constrained minimal-length networks acted on by a variety of forces that perturb and/or remodel the network. Here, we study two specific biophysical processes involved in remodeling. One is the dynamic relaxation process involving a combination of tubule tension and viscous forces. The other is the rapid creation of cross-connection tubules by direct or indirect interactions with cytoskeletal elements. These processes are able to remodel the ER network: the first reduces network length and complexity whereas the second increases both. Using live cell imaging of ER network dynamics in tobacco leaf epidermal cells, we examine these processes on ER network dynamics. Away from regions of cytoplasmic streaming, we suggest that the dynamic network structure is a balance between the two processes, and we build an integrative model of the two processes for network remodeling. This model produces quantitatively similar ER networks to those observed in experiments. We use the model to explore the effect of parameter variation on statistical properties of the ER network. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Effects of simplifying fracture network representation on inert chemical migration in fracture-controlled aquifers

USGS Publications Warehouse

Wellman, Tristan; Shapiro, Allen M.; Hill, Mary C.

2009-01-01

While it is widely recognized that highly permeable 'large-scale' fractures dominate chemical migration in many fractured aquifers, recent studies suggest that the pervasive 'small-scale' fracturing once considered of less significance can be equally important for characterizing the spatial extent and residence time associated with transport processes. A detailed examination of chemical migration through fracture-controlled aquifers is used to advance this conceptual understanding. The influence of fracture structure is evaluated by quantifying the effects to transport caused by a systematic removal of fractures from three-dimensional discrete fracture models whose attributes are derived from geologic and hydrologic conditions at multiple field sites. Results indicate that the effects to transport caused by network simplification are sensitive to the fracture network characteristics, degree of network simplification, and plume travel distance, but primarily in an indirect sense since correlation to individual attributes is limited. Transport processes can be 'enhanced' or 'restricted' from network simplification meaning that the elimination of fractures may increase or decrease mass migration, mean travel time, dispersion, and tailing of the concentration plume. The results demonstrate why, for instance, chemical migration may not follow the classic advection-dispersion equation where dispersion approximates the effect of the ignored geologic structure as a strictly additive process to the mean flow. The analyses further reveal that the prediction error caused by fracture network simplification is reduced by at least 50% using the median estimate from an ensemble of simplified fracture network models, and that the error from network simplification is at least 70% less than the stochastic variability from multiple realizations. Copyright 2009 by the American Geophysical Union.

Processes linked to contact changes in adoptive kinship networks.

PubMed

Dunbar, Nora; van Dulmen, Manfred H M; Ayers-Lopez, Susan; Berge, Jerica M; Christian, Cinda; Gossman, Ginger; Henney, M Susan M; Mendenhall, Tai J; Grotevant, Harold D; McRoy, Ruth G

2006-12-01

The purpose of this study was to reveal underlying processes in adoptive kinship networks that experienced increases or decreases in levels of openness during the child's adolescent years. Intensive case study analyses were conducted for 8 adoptive kinship networks (each including an adoptive mother, adoptive father, adopted adolescent, and birth mother), half of whom had experienced an increase in openness from indirect (mediated) to direct (fully disclosed) contact and half of whom had ceased indirect contact between Waves 1 and 2 of a longitudinal study. Adoptive mothers tended to be more involved in contact with the birth mother than were adoptive fathers or adopted adolescents. Members of adoptive kinship networks in which a decrease in level of contact took place had incongruent perspectives about who initiated the stop in contact and why the stop took place. Birth mothers were less satisfied with their degree of contact than were adoptive parents. Adults' satisfaction with contact was related to feelings of control over type and amount of interactions and permeability of family boundaries. In all adoptive kinship networks, responsibility for contact had shifted toward the adopted adolescent regardless of whether the adolescent was aware of this change in responsibility.

An indirect component in the evoked compound action potential of the vagal nerve.

PubMed

Ordelman, Simone C M A; Kornet, Lilian; Cornelussen, Richard; Buschman, Hendrik P J; Veltink, Peter H

2010-12-01

The vagal nerve plays a vital role in the regulation of the cardiovascular system. It not only regulates the heart but also sends sensory information from the heart back to the brain. We hypothesize that the evoked vagal nerve compound action potential contains components that are indirect via the brain stem or coming via the neural network on the heart. In an experimental study of 15 pigs, we identified four components in the evoked compound action potentials. The fourth component was found to be an indirect component, which came from the periphery. The latency of the indirect component increased when heart rate and contractility were decreased by burst stimulation (P = 0.01; n = 7). When heart rate and contractility were increased by dobutamine administration, the latency of the indirect component decreased (P = 0.01; n = 9). This showed that the latency of the indirect component of the evoked compound action potentials may relate to the state of the cardiovascular system.

A Summary of Sociological Concepts Related to Social Network and Its Techniques for Quantifying Social Cohesion, Social Position, Social Distance

DTIC Science & Technology

2013-01-16

the context of social networking sites , email communications, and virtual worlds, etc. They also, however, form indirect communities via the development...science. In the spring of 2011, access to social networking sites was largely hailed as a prime facilitator of individuals across North Africa and...at an astounding rate, particularly the use of social networking sites . The number of adult internet users in the United States doubled be- tween 2008

Functional network connectivity analysis based on partial correlation in Alzheimer's disease

NASA Astrophysics Data System (ADS)

Zhang, Nan; Guan, Xiaoting; Zhang, Yumei; Li, Jingjing; Chen, Hongyan; Chen, Kewei; Fleisher, Adam; Yao, Li; Wu, Xia

2009-02-01

Functional network connectivity (FNC) measures the temporal dependency among the time courses of functional networks. However, the marginal correlation between two networks used in the classic FNC analysis approach doesn't separate the FNC from the direct/indirect effects of other networks. In this study, we proposed an alternative approach based on partial correlation to evaluate the FNC, since partial correlation based FNC can reveal the direct interaction between a pair of networks, removing dependencies or influences from others. Previous studies have demonstrated less task-specific activation and less rest-state activity in Alzheimer's disease (AD). We applied present approach to contrast FNC differences of resting state network (RSN) between AD and normal controls (NC). The fMRI data under resting condition were collected from 15 AD and 16 NC. FNC was calculated for each pair of six RSNs identified using Group ICA, thus resulting in 15 (2 out of 6) pairs for each subject. Partial correlation based FNC analysis indicated 6 pairs significant differences between groups, while marginal correlation only revealed 2 pairs (involved in the partial correlation results). Additionally, patients showed lower correlation than controls among most of the FNC differences. Our results provide new evidences for the disconnection hypothesis in AD.

Contingent approach to Internet-based supply network integration

NASA Astrophysics Data System (ADS)

Ho, Jessica; Boughton, Nick; Kehoe, Dennis; Michaelides, Zenon

2001-10-01

The Internet is playing an increasingly important role in enhancing the operations of supply networks as many organizations begin to recognize the benefits of Internet- enabled supply arrangements. However, the developments and applications to-date do not extend significantly beyond the dyadic model, whereas the real advantages are to be made with the external and network models to support a coordinated and collaborative based approach. The DOMAIN research group at the University of Liverpool is currently defining new Internet- enabled approaches to enable greater collaboration across supply chains. Different e-business models and tools are focusing on different applications. Using inappropriate e- business models, tools or techniques will bring negative results instead of benefits to all the tiers in the supply network. Thus there are a number of issues to be considered before addressing Internet based supply network integration, in particular an understanding of supply chain management, the emergent business models and evaluating the effects of deploying e-business to the supply network or a particular tier. It is important to utilize a contingent approach to selecting the right e-business model to meet the specific supply chain requirements. This paper addresses the issues and provides a case study on the indirect materials supply networks.

Evolution of gossip-based indirect reciprocity on a bipartite network

PubMed Central

Giardini, Francesca; Vilone, Daniele

2016-01-01

Cooperation can be supported by indirect reciprocity via reputation. Thanks to gossip, reputations are built and circulated and humans can identify defectors and ostracise them. However, the evolutionary stability of gossip is allegedly undermined by the fact that it is more error-prone that direct observation, whereas ostracism could be ineffective if the partner selection mechanism is not robust. The aim of this work is to investigate the conditions under which the combination of gossip and ostracism might support cooperation in groups of different sizes. We are also interested in exploring the extent to which errors in transmission might undermine the reliability of gossip as a mechanism for identifying defectors. Our results show that a large quantity of gossip is necessary to support cooperation, and that group structure can mitigate the effects of errors in transmission. PMID:27885256

Evolution of gossip-based indirect reciprocity on a bipartite network.

PubMed

Giardini, Francesca; Vilone, Daniele

2016-11-25

Cooperation can be supported by indirect reciprocity via reputation. Thanks to gossip, reputations are built and circulated and humans can identify defectors and ostracise them. However, the evolutionary stability of gossip is allegedly undermined by the fact that it is more error-prone that direct observation, whereas ostracism could be ineffective if the partner selection mechanism is not robust. The aim of this work is to investigate the conditions under which the combination of gossip and ostracism might support cooperation in groups of different sizes. We are also interested in exploring the extent to which errors in transmission might undermine the reliability of gossip as a mechanism for identifying defectors. Our results show that a large quantity of gossip is necessary to support cooperation, and that group structure can mitigate the effects of errors in transmission.

Evolution of gossip-based indirect reciprocity on a bipartite network

NASA Astrophysics Data System (ADS)

Giardini, Francesca; Vilone, Daniele

2016-11-01

Cooperation can be supported by indirect reciprocity via reputation. Thanks to gossip, reputations are built and circulated and humans can identify defectors and ostracise them. However, the evolutionary stability of gossip is allegedly undermined by the fact that it is more error-prone that direct observation, whereas ostracism could be ineffective if the partner selection mechanism is not robust. The aim of this work is to investigate the conditions under which the combination of gossip and ostracism might support cooperation in groups of different sizes. We are also interested in exploring the extent to which errors in transmission might undermine the reliability of gossip as a mechanism for identifying defectors. Our results show that a large quantity of gossip is necessary to support cooperation, and that group structure can mitigate the effects of errors in transmission.

Life satisfaction and sexual minorities: Evidence from Australia and the United Kingdom

PubMed Central

Powdthavee, Nattavudh; Wooden, Mark

2017-01-01

Very little is known about how the differential treatment of sexual minorities could influence subjective reports of overall well-being. This paper seeks to fill this gap. Data from two large surveys that provide nationally representative samples for two different countries –Australia and the UK – are used to estimate a simultaneous equations model of life satisfaction. The model allows for self-reported sexual identity to influence a measure of life satisfaction both directly and indirectly through seven different channels: (i) income; (ii) employment; (iii) health (iv) marriage and de facto relationships; (v) children; (vi) friendship networks; and (vii) education. Lesbian, gay and bisexual persons are found to be significantly less satisfied with their lives than otherwise comparable heterosexual persons. In both countries this is the result of a combination of direct and indirect effects. PMID:29238117

Multi-year application of WRF-CAM5 over East Asia-Part II: Interannual variability, trend analysis, and aerosol indirect effects

NASA Astrophysics Data System (ADS)

Zhang, Yang; Wang, Kai; He, Jian

2017-09-01

Following a comprehensive evaluation of WRF-CAM5 in Part I, Part II describes analyses of interannual variability, multi-year variation trends, and the direct, indirect, and total effects of anthropogenic aerosols. The interannual variations of chemical column and surface concentrations, and ozone (O3)/particulate matter (PM) indicators are strongly correlated to anthropogenic emission changes. Despite model biases, the model captures well the observed interannual variations of temperature at 2-m, cloud fraction, shortwave cloud forcing, downwelling shortwave radiation, cloud droplet number concentration, column O3, and column formaldehyde (HCHO) for the whole domain. While the model reproduces the volatile organic compound (VOC)-limited regimes of O3 chemistry at sites in Hong Kong, Taiwan, Japan, South Korea, and from the Acid Deposition Monitoring Network in East Asia (EANET) and the degree of sulfate neutralization at the EANET sites, it has limited capability in capturing the interannual variations of the ratio of O3 and nitrogen dioxide (O3/NO2) and PM chemical regime indicators, due to uncertainties in the emissions of precursors for O3 and secondary PM, the model assumption for ammonium bisulfate (NH4HSO4) as well as lack of gas/particle partitioning of total ammonia and total nitrate. While the variation trends in multi-year periods in aerosol optical depth and column concentrations of carbon monoxide, sulfur dioxide, and NO2 are mainly caused by anthropogenic emissions, those of major meteorological and cloud variables partly reflect feedbacks of chemistry to meteorological variables. The impacts of anthropogenic aerosol indirect effects either dominate or play an important role in the aerosol total effects for most cloud and chemical predictions, whereas anthropogenic aerosol direct effects influence most meteorological and radiation variables. The direct, indirect, and total effects of anthropogenic aerosols exhibit a strong interannual variability in 2001, 2006, and 2011.

Family Transitions and Later Delinquency and Drug Use

PubMed Central

Krohn, Marvin D.; Hall, Gina Penly; Lizotte, Alan J.

2013-01-01

Changes in the family structure can be very disruptive to adolescents who live in those families. This article examines the impact of the number of family transitions on delinquent and drug-using behavior. Specifically, the effect of family transitions is hypothesized to be mediated by problems within the family, school, and peer settings. A sample of 646 boys (73%) and girls (27%) taken from a longitudinal panel study of high-risk adolescents are used to examine these hypotheses. For girls, little support is found for the direct or the indirect effect of family transitions on delinquent behavior or drug use. For boys, however, both forms of problem behavior are influenced by family transitions directly and indirectly through changes in, and problems with, peer associations. The findings suggest that during times of family turmoil, the friendship network of adolescent male children is also disrupted, leading to an increase in associations with delinquent others and, in turn, an increase in problematic behaviors. PMID:19636758

Heterogeneity in multiple transmission pathways: modelling the spread of cholera and other waterborne disease in networks with a common water source.

PubMed

Robertson, Suzanne L; Eisenberg, Marisa C; Tien, Joseph H

2013-01-01

Many factors influencing disease transmission vary throughout and across populations. For diseases spread through multiple transmission pathways, sources of variation may affect each transmission pathway differently. In this paper we consider a disease that can be spread via direct and indirect transmission, such as the waterborne disease cholera. Specifically, we consider a system of multiple patches with direct transmission occurring entirely within patch and indirect transmission via a single shared water source. We investigate the effect of heterogeneity in dual transmission pathways on the spread of the disease. We first present a 2-patch model for which we examine the effect of variation in each pathway separately and propose a measure of heterogeneity that incorporates both transmission mechanisms and is predictive of R(0). We also explore how heterogeneity affects the final outbreak size and the efficacy of intervention measures. We conclude by extending several results to a more general n-patch setting.

CHD8 regulates neurodevelopmental pathways associated with autism spectrum disorder in neural progenitors

PubMed Central

Sugathan, Aarathi; Biagioli, Marta; Golzio, Christelle; Erdin, Serkan; Blumenthal, Ian; Manavalan, Poornima; Ragavendran, Ashok; Brand, Harrison; Lucente, Diane; Miles, Judith; Sheridan, Steven D.; Stortchevoi, Alexei; Kellis, Manolis; Haggarty, Stephen J.; Katsanis, Nicholas; Gusella, James F.; Talkowski, Michael E.

2014-01-01

Truncating mutations of chromodomain helicase DNA-binding protein 8 (CHD8), and of many other genes with diverse functions, are strong-effect risk factors for autism spectrum disorder (ASD), suggesting multiple mechanisms of pathogenesis. We explored the transcriptional networks that CHD8 regulates in neural progenitor cells (NPCs) by reducing its expression and then integrating transcriptome sequencing (RNA sequencing) with genome-wide CHD8 binding (ChIP sequencing). Suppressing CHD8 to levels comparable with the loss of a single allele caused altered expression of 1,756 genes, 64.9% of which were up-regulated. CHD8 showed widespread binding to chromatin, with 7,324 replicated sites that marked 5,658 genes. Integration of these data suggests that a limited array of direct regulatory effects of CHD8 produced a much larger network of secondary expression changes. Genes indirectly down-regulated (i.e., without CHD8-binding sites) reflect pathways involved in brain development, including synapse formation, neuron differentiation, cell adhesion, and axon guidance, whereas CHD8-bound genes are strongly associated with chromatin modification and transcriptional regulation. Genes associated with ASD were strongly enriched among indirectly down-regulated loci (P < 10−8) and CHD8-bound genes (P = 0.0043), which align with previously identified coexpression modules during fetal development. We also find an intriguing enrichment of cancer-related gene sets among CHD8-bound genes (P < 10−10). In vivo suppression of chd8 in zebrafish produced macrocephaly comparable to that of humans with inactivating mutations. These data indicate that heterozygous disruption of CHD8 precipitates a network of gene-expression changes involved in neurodevelopmental pathways in which many ASD-associated genes may converge on shared mechanisms of pathogenesis. PMID:25294932

A spiking neural network based on the basal ganglia functional anatomy.

PubMed

Baladron, Javier; Hamker, Fred H

2015-07-01

We introduce a spiking neural network of the basal ganglia capable of learning stimulus-action associations. We model learning in the three major basal ganglia pathways, direct, indirect and hyperdirect, by spike time dependent learning and considering the amount of dopamine available (reward). Moreover, we allow to learn a cortico-thalamic pathway that bypasses the basal ganglia. As a result the system develops new functionalities for the different basal ganglia pathways: The direct pathway selects actions by disinhibiting the thalamus, the hyperdirect one suppresses alternatives and the indirect pathway learns to inhibit common mistakes. Numerical experiments show that the system is capable of learning sets of either deterministic or stochastic rules. Copyright © 2015 Elsevier Ltd. All rights reserved.

The third wheel: the impact of Twitter use on relationship infidelity and divorce.

PubMed

Clayton, Russell B

2014-07-01

The purpose of this study was to examine how social networking site (SNS) use, specifically Twitter use, influences negative interpersonal relationship outcomes. This study specifically examined the mediational effect of Twitter-related conflict on the relationship between active Twitter use and negative relationship outcomes, and how this mechanism may be contingent on the length of the romantic relationship. A total of 581 Twitter users aged 18 to 67 years (Mage=29, SDage=8.9) completed an online survey questionnaire. Moderation-mediation regression analyses using bootstrapping methods indicated that Twitter-related conflict mediated the relationship between active Twitter use and negative relationship outcomes. The length of the romantic relationship, however, did not moderate the indirect effect on the relationship between active Twitter use and negative relationship outcomes. The results from this study suggest that active Twitter use leads to greater amounts of Twitter-related conflict among romantic partners, which in turn leads to infidelity, breakup, and divorce. This indirect effect is not contingent on the length of the romantic relationship. The current study adds to the growing body of literature investigating SNS use and romantic relationship outcomes.

Randomizing world trade. II. A weighted network analysis

NASA Astrophysics Data System (ADS)

Squartini, Tiziano; Fagiolo, Giorgio; Garlaschelli, Diego

2011-10-01

Based on the misleading expectation that weighted network properties always offer a more complete description than purely topological ones, current economic models of the International Trade Network (ITN) generally aim at explaining local weighted properties, not local binary ones. Here we complement our analysis of the binary projections of the ITN by considering its weighted representations. We show that, unlike the binary case, all possible weighted representations of the ITN (directed and undirected, aggregated and disaggregated) cannot be traced back to local country-specific properties, which are therefore of limited informativeness. Our two papers show that traditional macroeconomic approaches systematically fail to capture the key properties of the ITN. In the binary case, they do not focus on the degree sequence and hence cannot characterize or replicate higher-order properties. In the weighted case, they generally focus on the strength sequence, but the knowledge of the latter is not enough in order to understand or reproduce indirect effects.

Fuzzy wavelet plus a quantum neural network as a design base for power system stability enhancement.

PubMed

Ganjefar, Soheil; Tofighi, Morteza; Karami, Hamidreza

2015-11-01

In this study, we introduce an indirect adaptive fuzzy wavelet neural controller (IAFWNC) as a power system stabilizer to damp inter-area modes of oscillations in a multi-machine power system. Quantum computing is an efficient method for improving the computational efficiency of neural networks, so we developed an identifier based on a quantum neural network (QNN) to train the IAFWNC in the proposed scheme. All of the controller parameters are tuned online based on the Lyapunov stability theory to guarantee the closed-loop stability. A two-machine, two-area power system equipped with a static synchronous series compensator as a series flexible ac transmission system was used to demonstrate the effectiveness of the proposed controller. The simulation and experimental results demonstrated that the proposed IAFWNC scheme can achieve favorable control performance. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sediment and Vegetation Controls on Delta Channel Networks

NASA Astrophysics Data System (ADS)

Lauzon, R.; Murray, A. B.; Piliouras, A.; Kim, W.

2016-12-01

Numerous factors control the patterns of distributary channels formed on a delta, including water and sediment discharge, grain size, sea level rise rates, and vegetation type. In turn, these channel networks influence the shape and evolution of a delta, including what types of plant and animal life - such as humans - it can support. Previous fluvial modeling and flume experiments, outside of the delta context, have addressed how interactions between sediment and vegetation, through their influence on lateral transport of sediment, determine what type of channel networks develops. Similar interactions likely also shape delta flow patterns. Vegetation introduces cohesion, tending to reduce channel migration rates and strengthen existing channel banks, reinforcing existing channels and resulting in localized, relatively stable flow patterns. On the other hand, sediment transport processes can result in lateral migration and frequent switching of active channels, resulting in flow resembling that of a braided stream. While previous studies of deltas have indirectly explored the effects of vegetation through the introduction of cohesive sediment, we directly incorporate key effects of vegetation on flow and sediment transport into the delta-building model DeltaRCM to explore how these effects influence delta channel network formation. Model development is informed by laboratory flume experiments at UT Austin. Here we present initial results of experiments exploring the effects of sea level rise rate, sediment grain size, vegetation type, and vegetation growth rate on delta channel network morphology. These results support the hypothesis that the ability for lateral transport of sediment to occur plays a key role in determining the evolution of delta channel networks and delta morphology.

Paule‐Mandel estimators for network meta‐analysis with random inconsistency effects

PubMed Central

Veroniki, Areti Angeliki; Law, Martin; Tricco, Andrea C.; Baker, Rose

2017-01-01

Network meta‐analysis is used to simultaneously compare multiple treatments in a single analysis. However, network meta‐analyses may exhibit inconsistency, where direct and different forms of indirect evidence are not in agreement with each other, even after allowing for between‐study heterogeneity. Models for network meta‐analysis with random inconsistency effects have the dual aim of allowing for inconsistencies and estimating average treatment effects across the whole network. To date, two classical estimation methods for fitting this type of model have been developed: a method of moments that extends DerSimonian and Laird's univariate method and maximum likelihood estimation. However, the Paule and Mandel estimator is another recommended classical estimation method for univariate meta‐analysis. In this paper, we extend the Paule and Mandel method so that it can be used to fit models for network meta‐analysis with random inconsistency effects. We apply all three estimation methods to a variety of examples that have been used previously and we also examine a challenging new dataset that is highly heterogenous. We perform a simulation study based on this new example. We find that the proposed Paule and Mandel method performs satisfactorily and generally better than the previously proposed method of moments because it provides more accurate inferences. Furthermore, the Paule and Mandel method possesses some advantages over likelihood‐based methods because it is both semiparametric and requires no convergence diagnostics. Although restricted maximum likelihood estimation remains the gold standard, the proposed methodology is a fully viable alternative to this and other estimation methods. PMID:28585257

The behaviour of basic autocatalytic signalling modules in isolation and embedded in networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krishnan, J.; Mois, Kristina; Suwanmajo, Thapanar

2014-11-07

In this paper, we examine the behaviour of basic autocatalytic feedback modules involving a species catalyzing its own production, either directly or indirectly. We first perform a systematic study of the autocatalytic feedback module in isolation, examining the effect of different factors, showing how this module is capable of exhibiting monostable threshold and bistable switch-like behaviour. We then study the behaviour of this module embedded in different kinds of basic networks including (essentially) irreversible cycles, open and closed reversible chains, and networks with additional feedback. We study the behaviour of the networks deterministically and also stochastically, using simulations, analytical work,more » and bifurcation analysis. We find that (i) there are significant differences between the behaviour of this module in isolation and in a network: thresholds may be altered or destroyed and bistability may be destroyed or even induced, even when the ambient network is simple. The global characteristics and topology of this network and the position of the module in the ambient network can play important and unexpected roles. (ii) There can be important differences between the deterministic and stochastic dynamics of the module embedded in networks, which may be accentuated by the ambient network. This provides new insights into the functioning of such enzymatic modules individually and as part of networks, with relevance to other enzymatic signalling modules as well.« less

The behaviour of basic autocatalytic signalling modules in isolation and embedded in networks

NASA Astrophysics Data System (ADS)

Krishnan, J.; Mois, Kristina; Suwanmajo, Thapanar

2014-11-01

In this paper, we examine the behaviour of basic autocatalytic feedback modules involving a species catalyzing its own production, either directly or indirectly. We first perform a systematic study of the autocatalytic feedback module in isolation, examining the effect of different factors, showing how this module is capable of exhibiting monostable threshold and bistable switch-like behaviour. We then study the behaviour of this module embedded in different kinds of basic networks including (essentially) irreversible cycles, open and closed reversible chains, and networks with additional feedback. We study the behaviour of the networks deterministically and also stochastically, using simulations, analytical work, and bifurcation analysis. We find that (i) there are significant differences between the behaviour of this module in isolation and in a network: thresholds may be altered or destroyed and bistability may be destroyed or even induced, even when the ambient network is simple. The global characteristics and topology of this network and the position of the module in the ambient network can play important and unexpected roles. (ii) There can be important differences between the deterministic and stochastic dynamics of the module embedded in networks, which may be accentuated by the ambient network. This provides new insights into the functioning of such enzymatic modules individually and as part of networks, with relevance to other enzymatic signalling modules as well.

Predicting community responses to perturbations in the face of imperfect knowledge and network complexity

USGS Publications Warehouse

Novak, M.; Wootton, J.T.; Doak, D.F.; Emmerson, M.; Estes, J.A.; Tinker, M.T.

2011-01-01

How best to predict the effects of perturbations to ecological communities has been a long-standing goal for both applied and basic ecology. This quest has recently been revived by new empirical data, new analysis methods, and increased computing speed, with the promise that ecologically important insights may be obtainable from a limited knowledge of community interactions. We use empirically based and simulated networks of varying size and connectance to assess two limitations to predicting perturbation responses in multispecies communities: (1) the inaccuracy by which species interaction strengths are empirically quantified and (2) the indeterminacy of species responses due to indirect effects associated with network size and structure. We find that even modest levels of species richness and connectance (??25 pairwise interactions) impose high requirements for interaction strength estimates because system indeterminacy rapidly overwhelms predictive insights. Nevertheless, even poorly estimated interaction strengths provide greater average predictive certainty than an approach that uses only the sign of each interaction. Our simulations provide guidance in dealing with the trade-offs involved in maximizing the utility of network approaches for predicting dynamics in multispecies communities. ?? 2011 by the Ecological Society of America.

Node-Splitting Generalized Linear Mixed Models for Evaluation of Inconsistency in Network Meta-Analysis.

PubMed

Yu-Kang, Tu

2016-12-01

Network meta-analysis for multiple treatment comparisons has been a major development in evidence synthesis methodology. The validity of a network meta-analysis, however, can be threatened by inconsistency in evidence within the network. One particular issue of inconsistency is how to directly evaluate the inconsistency between direct and indirect evidence with regard to the effects difference between two treatments. A Bayesian node-splitting model was first proposed and a similar frequentist side-splitting model has been put forward recently. Yet, assigning the inconsistency parameter to one or the other of the two treatments or splitting the parameter symmetrically between the two treatments can yield different results when multi-arm trials are involved in the evaluation. We aimed to show that a side-splitting model can be viewed as a special case of design-by-treatment interaction model, and different parameterizations correspond to different design-by-treatment interactions. We demonstrated how to evaluate the side-splitting model using the arm-based generalized linear mixed model, and an example data set was used to compare results from the arm-based models with those from the contrast-based models. The three parameterizations of side-splitting make slightly different assumptions: the symmetrical method assumes that both treatments in a treatment contrast contribute to inconsistency between direct and indirect evidence, whereas the other two parameterizations assume that only one of the two treatments contributes to this inconsistency. With this understanding in mind, meta-analysts can then make a choice about how to implement the side-splitting method for their analysis. Copyright © 2016 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

The Influence of Social Support on Smoking Cessation Treatment Adherence Among HIV+ Smokers.

PubMed

de Dios, Marcel A; Stanton, Cassandra A; Cano, Miguel Ángel; Lloyd-Richardson, Elizabeth; Niaura, Raymond

2016-05-01

The high prevalence of smoking among people living with HIV is a significant problem. Nonadherence to smoking cessation pharmacotherapy is a barrier for successfully quitting. The current study investigated the extent to which social support variables impact adherence and cessation. Participants were 444 HIV+ smokers who provided data on nicotine patch adherence, social support, and smoking. We conducted a path analysis to estimate (1) the effects of six social support indicators at baseline on nicotine patch adherence; (2) the effect of patch adherence on 7-day point prevalence smoking at 6-month follow-up; and (3) the indirect effects of social support indicators on 7-day point prevalence smoking at 6-month follow-up via patch adherence. The tested model demonstrated good fit as indicated by the comparative fit index, root mean square error of approximation, and weighted root mean square residual (0.94, 0.02, and 0.51, respectively). Path analysis results indicated greater social support network contact was associated with higher levels of nicotine patch adherence (β = .13, P = .02), greater patch adherence was associated with a lower probability of 7-day point prevalence smoking at 6-month follow-up (β = -.47, P < .001) and greater social support network contact (β = -.06, P = .03) had a significant indirect effect on 7-day point prevalence smoking at 6-month follow-up via patch adherence. Findings have implications for smoking cessation interventions that seek to capitalize on the beneficial effects of social support. Such efforts should account for the role that frequency of contact may have on nicotine patch use and other treatment-related mechanisms. © The Author 2015. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

An indirect estimation of the population size of students with high-risk behaviors in select universities of medical sciences: A network scale-up study.

PubMed

Sajjadi, Homeira; Jorjoran Shushtari, Zahra; Shati, Mohsen; Salimi, Yahya; Dejman, Masoomeh; Vameghi, Meroe; Karimi, Salahedin; Mahmoodi, Zohreh

2018-01-01

Network scale-up is one of the most important indirect methods of estimating the size of clandestine populations and people with high-risk behaviors. The present study is an indirect estimation of the population size of students with high-risk behaviors in select universities of medical sciences. A total of 801 students from two University of Medical Sciences at Tehran and Alborz University of Medical Sciences were selected through convenience sampling. Six subgroups of high-risk behaviors were examined in the study, including Tramadol use, cannabis use, opium use, alcohol consumption, extramarital heterosexual intercourse, and heterosexual intercourse in return for money. To estimate the social network size in the study population, each participant was asked to name their close student friends from the two select universities. Data were collected using a checklist designed for this purpose. The participants' mean number of close friends from the selected medical universities was C = 8.14 (CI: 7.54-8.75). Within these social networks, friends with extramarital heterosexual intercourse (5.53%) and friends who consumed alcohol (4.92%) had the highest frequency, and friends who used opium (0.33%) had the lowest frequency. The variables of age, gender, marital status, type of residence and academic degree were significantly related to the likelihood of having close friends with certain high-risk behaviors (P<0.001). According to the results obtained, alcohol consumption and extramarital heterosexual intercourse are very common among students. Special HIV prevention programs are therefore necessary for this age group.

Adolescent Problematic Social Networking and School Experiences: The Mediating Effects of Sleep Disruptions and Sleep Quality.

PubMed

Vernon, Lynette; Barber, Bonnie L; Modecki, Kathryn L

2015-07-01

An important developmental task for adolescents is to become increasingly responsible for their own health behaviors. Establishing healthy sleep routines and controlling media use before bedtime are important for adequate, quality sleep so adolescents are alert during the day and perform well at school. Despite the prevalence of adolescent social media use and the large percentage of computers and cell phones in adolescents' bedrooms, no studies to date have investigated the link between problematic adolescent investment in social networking, their sleep practices, and associated experiences at school. A sample of 1,886 students in Australia aged between 12 and 18 years of age completed self-report data on problematic social networking use, sleep disturbances, sleep quality, and school satisfaction. Structural equation modeling (SEM) substantiated the serial mediation hypothesis: for adolescents, problematic social networking use significantly increased sleep disturbances, which adversely affected perceptions of sleep quality that, in turn, lowered adolescents' appraisals of their school satisfaction. This significant pattern was largely driven by the indirect effect of sleep disturbances. These findings suggest that adolescents are vulnerable to negative consequences from social networking use. Specifically, problematic social networking is associated with poor school experiences, which result from poor sleep habits. Promoting better sleep routines by minimizing sleep disturbances from social media use could improve school experiences for adolescents with enhanced emotional engagement and improved subjective well-being.

Construction of Large-Volume Tissue Mimics with 3D Functional Vascular Networks

PubMed Central

Kang, Tae-Yun; Hong, Jung Min; Jung, Jin Woo; Kang, Hyun-Wook; Cho, Dong-Woo

2016-01-01

We used indirect stereolithography (SL) to form inner-layered fluidic networks in a porous scaffold by introducing a hydrogel barrier on the luminal surface, then seeded the networks separately with human umbilical vein endothelial cells and human lung fibroblasts to form a tissue mimic containing vascular networks. The artificial vascular networks provided channels for oxygen transport, thus reducing the hypoxic volume and preventing cell death. The endothelium of the vascular networks significantly retarded the occlusion of channels during whole-blood circulation. The tissue mimics have the potential to be used as an in vitro platform to examine the physiologic and pathologic phenomena through vascular architecture. PMID:27228079

Triadic Relations in a Game of Pachisi

ERIC Educational Resources Information Center

Wu, Zhaohui; Choi, Thomas Y.

2013-01-01

A triad is the smallest network form where one can study how a link affects a link or a node affects a link indirectly connected. Through triads, one can glimpse the more complex relational dynamics in larger networks. Studies of various triadic relationships have gained growing interest among OM scholars in recent years as both researchers and…

Testing moderation in network meta-analysis with individual participant data

PubMed Central

Dagne, Getachew A.; Brown, C. Hendricks; Howe, George; Kellam, Sheppard G.; Liu, Lei

2016-01-01

Summary Meta-analytic methods for combining data from multiple intervention trials are commonly used to estimate the effectiveness of an intervention. They can also be extended to study comparative effectiveness, testing which of several alternative interventions is expected to have the strongest effect. This often requires network meta-analysis (NMA), which combines trials involving direct comparison of two interventions within the same trial and indirect comparisons across trials. In this paper, we extend existing network methods for main effects to examining moderator effects, allowing for tests of whether intervention effects vary for different populations or when employed in different contexts. In addition, we study how the use of individual participant data (IPD) may increase the sensitivity of NMA for detecting moderator effects, as compared to aggregate data NMA that employs study-level effect sizes in a meta-regression framework. A new network meta-analysis diagram is proposed. We also develop a generalized multilevel model for NMA that takes into account within- and between-trial heterogeneity, and can include participant-level covariates. Within this framework we present definitions of homogeneity and consistency across trials. A simulation study based on this model is used to assess effects on power to detect both main and moderator effects. Results show that power to detect moderation is substantially greater when applied to IPD as compared to study-level effects. We illustrate the use of this method by applying it to data from a classroom-based randomized study that involved two sub-trials, each comparing interventions that were contrasted with separate control groups. PMID:26841367

The Hierarchy of Brain Networks Is Related to Insulin Growth Factor-1 in a Large, Middle-Aged, Healthy Cohort: An Exploratory Magnetoencephalography Study.

PubMed

Sorrentino, Pierpaolo; Nieboer, Dagmar; Twisk, Jos W R; Stam, Cornelis J; Douw, Linda; Hillebrand, Arjan

2017-06-01

Recently, a large study demonstrated that lower serum levels of insulin growth factor-1 (IGF-1) relate to brain atrophy and to a greater risk for developing Alzheimer's disease in a healthy elderly population. We set out to test if functional brain networks relate to IGF-1 levels in the middle aged. Hence, we studied the association between IGF-1 and magnetoencephalography-based functional network characteristics in a middle-aged population. The functional connections between brain areas were estimated for six frequency bands (delta, theta, alpha1, alpha2, beta, gamma) using the phase lag index. Subsequently, the topology of the frequency-specific functional networks was characterized using the minimum spanning tree. Our results showed that lower levels of serum IGF-1 relate to a globally less integrated functional network in the beta and theta band. The associations remained significant when correcting for gender and systemic effects of IGF-1 that might indirectly affect the brain. The value of this exploratory study is the demonstration that lower levels of IGF-1 are associated with brain network topology in the middle aged.

Road networks predict human influence on Amazonian bird communities

PubMed Central

Ahmed, Sadia E.; Lees, Alexander C.; Moura, Nárgila G.; Gardner, Toby A.; Barlow, Jos; Ferreira, Joice; Ewers, Robert M.

2014-01-01

Road building can lead to significant deleterious impacts on biodiversity, varying from direct road-kill mortality and direct habitat loss associated with road construction, to more subtle indirect impacts from edge effects and fragmentation. However, little work has been done to evaluate the specific effects of road networks and biodiversity loss beyond the more generalized effects of habitat loss. Here, we compared forest bird species richness and composition in the municipalities of Santarém and Belterra in Pará state, eastern Brazilian Amazon, with a road network metric called ‘roadless volume (RV)’ at the scale of small hydrological catchments (averaging 3721 ha). We found a significant positive relationship between RV and both forest bird richness and the average number of unique species (species represented by a single record) recorded at each site. Forest bird community composition was also significantly affected by RV. Moreover, there was no significant correlation between RV and forest cover, suggesting that road networks may impact biodiversity independently of changes in forest cover. However, variance partitioning analysis indicated that RV has partially independent and therefore additive effects, suggesting that RV and forest cover are best used in a complementary manner to investigate changes in biodiversity. Road impacts on avian species richness and composition independent of habitat loss may result from road-dependent habitat disturbance and fragmentation effects that are not captured by total percentage habitat cover, such as selective logging, fire, hunting, traffic disturbance, edge effects and road-induced fragmentation. PMID:25274363

Mapping Gnss Restricted Environments with a Drone Tandem and Indirect Position Control

NASA Astrophysics Data System (ADS)

Cledat, E.; Cucci, D. A.

2017-08-01

The problem of autonomously mapping highly cluttered environments, such as urban and natural canyons, is intractable with the current UAV technology. The reason lies in the absence or unreliability of GNSS signals due to partial sky occlusion or multi-path effects. High quality carrier-phase observations are also required in efficient mapping paradigms, such as Assisted Aerial Triangulation, to achieve high ground accuracy without the need of dense networks of ground control points. In this work we consider a drone tandem in which the first drone flies outside the canyon, where GNSS constellation is ideal, visually tracks the second drone and provides an indirect position control for it. This enables both autonomous guidance and accurate mapping of GNSS restricted environments without the need of ground control points. We address the technical feasibility of this concept considering preliminary real-world experiments in comparable conditions and we perform a mapping accuracy prediction based on a simulation scenario.

Social power, conflict policing, and the role of subordination signals in rhesus macaque society

PubMed Central

Beisner, Brianne A.; Hannibal, Darcy L.; Finn, Kelly R.; Fushing, Hsieh; McCowan, Brenda

2017-01-01

Objectives Policing is a conflict-limiting mechanism observed in many primate species. It is thought to require a skewed distribution of social power for some individuals to have sufficiently high social power to stop others’ fights, yet social power has not been examined in most species with policing behavior. We examined networks of subordination signals as a source of social power that permits policing behavior in rhesus macaques. Materials and Methods For each of seven captive groups of rhesus macaques, we (a) examined the structure of subordination signal networks and used GLMs to examine the relationship between (b) pairwise dominance certainty and subordination network pathways and (c) policing frequency and social power (group-level convergence in subordination signaling pathways). Results Networks of subordination signals had perfect linear transitivity, and pairs connected by both direct and indirect pathways of signals had more certain dominance relationships than pairs with no such network connection. Social power calculated using both direct and indirect network pathways showed a heavy-tailed distribution and positively predicted conflict policing. Conclusions Our results empirically substantiate that subordination signaling is associated with greater dominance relationship certainty and further show that pairs who signal rarely (or not at all) may use information from others’ signaling interactions to infer or reaffirm the relative certainty of their own relationships. We argue that the network of formal dominance relationships is central to societal stability because it is important for relationship stability and also supports the additional stabilizing mechanism of policing. PMID:26801956

Social power, conflict policing, and the role of subordination signals in rhesus macaque society.

PubMed

Beisner, Brianne A; Hannibal, Darcy L; Finn, Kelly R; Fushing, Hsieh; McCowan, Brenda

2016-05-01

Policing is a conflict-limiting mechanism observed in many primate species. It is thought to require a skewed distribution of social power for some individuals to have sufficiently high social power to stop others' fights, yet social power has not been examined in most species with policing behavior. We examined networks of subordination signals as a source of social power that permits policing behavior in rhesus macaques. For each of seven captive groups of rhesus macaques, we (a) examined the structure of subordination signal networks and used GLMs to examine the relationship between (b) pairwise dominance certainty and subordination network pathways and (c) policing frequency and social power (group-level convergence in subordination signaling pathways). Networks of subordination signals had perfect linear transitivity, and pairs connected by both direct and indirect pathways of signals had more certain dominance relationships than pairs with no such network connection. Social power calculated using both direct and indirect network pathways showed a heavy-tailed distribution and positively predicted conflict policing. Our results empirically substantiate that subordination signaling is associated with greater dominance relationship certainty and further show that pairs who signal rarely (or not at all) may use information from others' signaling interactions to infer or reaffirm the relative certainty of their own relationships. We argue that the network of formal dominance relationships is central to societal stability because it is important for relationship stability and also supports the additional stabilizing mechanism of policing. © 2016 Wiley Periodicals, Inc.

Structure-Function Network Mapping and Its Assessment via Persistent Homology

PubMed Central

2017-01-01

Understanding the relationship between brain structure and function is a fundamental problem in network neuroscience. This work deals with the general method of structure-function mapping at the whole-brain level. We formulate the problem as a topological mapping of structure-function connectivity via matrix function, and find a stable solution by exploiting a regularization procedure to cope with large matrices. We introduce a novel measure of network similarity based on persistent homology for assessing the quality of the network mapping, which enables a detailed comparison of network topological changes across all possible thresholds, rather than just at a single, arbitrary threshold that may not be optimal. We demonstrate that our approach can uncover the direct and indirect structural paths for predicting functional connectivity, and our network similarity measure outperforms other currently available methods. We systematically validate our approach with (1) a comparison of regularized vs. non-regularized procedures, (2) a null model of the degree-preserving random rewired structural matrix, (3) different network types (binary vs. weighted matrices), and (4) different brain parcellation schemes (low vs. high resolutions). Finally, we evaluate the scalability of our method with relatively large matrices (2514x2514) of structural and functional connectivity obtained from 12 healthy human subjects measured non-invasively while at rest. Our results reveal a nonlinear structure-function relationship, suggesting that the resting-state functional connectivity depends on direct structural connections, as well as relatively parsimonious indirect connections via polysynaptic pathways. PMID:28046127

Continuously updated network meta-analysis and statistical monitoring for timely decision-making

PubMed Central

Nikolakopoulou, Adriani; Mavridis, Dimitris; Egger, Matthias; Salanti, Georgia

2016-01-01

Pairwise and network meta-analysis (NMA) are traditionally used retrospectively to assess existing evidence. However, the current evidence often undergoes several updates as new studies become available. In each update recommendations about the conclusiveness of the evidence and the need of future studies need to be made. In the context of prospective meta-analysis future studies are planned as part of the accumulation of the evidence. In this setting, multiple testing issues need to be taken into account when the meta-analysis results are interpreted. We extend ideas of sequential monitoring of meta-analysis to provide a methodological framework for updating NMAs. Based on the z-score for each network estimate (the ratio of effect size to its standard error) and the respective information gained after each study enters NMA we construct efficacy and futility stopping boundaries. A NMA treatment effect is considered conclusive when it crosses an appended stopping boundary. The methods are illustrated using a recently published NMA where we show that evidence about a particular comparison can become conclusive via indirect evidence even if no further trials address this comparison. PMID:27587588

Indirect Effects of Environmental Change in Resource Competition Models.

PubMed

Kleinhesselink, Andrew R; Adler, Peter B

2015-12-01

Anthropogenic environmental change can affect species directly by altering physiological rates or indirectly by changing competitive outcomes. The unknown strength of competition-mediated indirect effects makes it difficult to predict species abundances in the face of ongoing environmental change. Theory developed with phenomenological competition models shows that indirect effects are weak when coexistence is strongly stabilized, but these models lack a mechanistic link between environmental change and species performance. To extend existing theory, we examined the relationship between coexistence and indirect effects in mechanistic resource competition models. We defined environmental change as a change in resource supply points and quantified the resulting competition-mediated indirect effects on species abundances. We found that the magnitude of indirect effects increases in proportion to niche overlap. However, indirect effects also depend on differences in how competitors respond to the change in resource supply, an insight hidden in nonmechanistic models. Our analysis demonstrates the value of using niche overlap to predict the strength of indirect effects and clarifies the types of indirect effects that global change can have on competing species.

Dynamics and Adaptive Control for Stability Recovery of Damaged Aircraft

NASA Technical Reports Server (NTRS)

Nguyen, Nhan; Krishnakumar, Kalmanje; Kaneshige, John; Nespeca, Pascal

2006-01-01

This paper presents a recent study of a damaged generic transport model as part of a NASA research project to investigate adaptive control methods for stability recovery of damaged aircraft operating in off-nominal flight conditions under damage and or failures. Aerodynamic modeling of damage effects is performed using an aerodynamic code to assess changes in the stability and control derivatives of a generic transport aircraft. Certain types of damage such as damage to one of the wings or horizontal stabilizers can cause the aircraft to become asymmetric, thus resulting in a coupling between the longitudinal and lateral motions. Flight dynamics for a general asymmetric aircraft is derived to account for changes in the center of gravity that can compromise the stability of the damaged aircraft. An iterative trim analysis for the translational motion is developed to refine the trim procedure by accounting for the effects of the control surface deflection. A hybrid direct-indirect neural network, adaptive flight control is proposed as an adaptive law for stabilizing the rotational motion of the damaged aircraft. The indirect adaptation is designed to estimate the plant dynamics of the damaged aircraft in conjunction with the direct adaptation that computes the control augmentation. Two approaches are presented 1) an adaptive law derived from the Lyapunov stability theory to ensure that the signals are bounded, and 2) a recursive least-square method for parameter identification. A hardware-in-the-loop simulation is conducted and demonstrates the effectiveness of the direct neural network adaptive flight control in the stability recovery of the damaged aircraft. A preliminary simulation of the hybrid adaptive flight control has been performed and initial data have shown the effectiveness of the proposed hybrid approach. Future work will include further investigations and high-fidelity simulations of the proposed hybrid adaptive Bight control approach.

Efficacy of antidepressive medication for depression in Parkinson disease: a network meta-analysis

PubMed Central

Zhuo, Chuanjun; Xue, Rong; Luo, Lanlan; Ji, Feng; Tian, Hongjun; Qu, Hongru; Lin, Xiaodong; Jiang, Ronghuan; Tao, Ran

2017-01-01

Abstract Background: Parkinson disease (PD) was considered as the 2nd most prevalent neurodegenerative disorder after Alzheimer disease, while depression is a prevailing nonmotor symptom of PD. Typically used antidepression medication includes tricyclic antidepressants (TCA), selective serotonin reuptake inhibitors (SSRI), serotonin and norepinephrine reuptake inhibitors (SNRI), monoamine-oxidase inhibitors (MAOI), and dopamine agonists (DA). Our study aimed at evaluating the efficacy of antidepressive medications for depression of PD. Methods: Web of Science, PubMed, Embase, and the Cochrane library were searched for related articles. Traditional meta-analysis and network meta-analysis (NMA) were performed with outcomes including depression score, UPDRS-II, UPDRS-III, and adverse effects. Surface under the cumulative ranking curve (SUCRA) was also performed to illustrate the rank probabilities of different medications on various outcomes. The consistency of direct and indirect evidence was also assessed by node-splitting method. Results: Results of traditional pairwise meta-analysis were performed. Concerning depression score, significant improvement was observed in AD, MAOI, SSRI, and SNRI compared with placebo. NMA was performed and more information could be obtained. DA was illustrated to be effective over placebo concerning UPDRS-III, MAOI, and SNRI. DA demonstrated a better prognosis in UPDRS-II scores compared with placebo and MAOI. However, DA and SSRI demonstrated a significant increase in adverse effects compared with placebo. The SUCRA value was calculated to evaluate the ranking probabilities of all medications on investigated outcomes, and the consistency between direct and indirect evidences was assessed by node-splitting method. Conclusion: SSRI had a satisfying efficacy for the depression of PD patients and could improve activities of daily living and motor function of patient but the adverse effects are unneglectable. SNRI are the safest medication with high efficacy for depression as well while other outcomes are relatively poor. PMID:28562526

Nursing work stress: the impacts of social network structure and organizational citizenship behavior.

PubMed

Tsang, Seng-Su; Chen, Tzu-Yin; Wang, Shih-Fong; Tai, Hsin-Ling

2012-03-01

The nursing workplace imposes significantly more stress on its employees than other workplace settings. Organizational resources, both physical and psychological, have been recognized in prior studies as important alleviators of nursing workplace stress. Whereas physical resources are less difficult to manipulate because of their tangibility, psychological resources, particularly psychological support from colleagues, are typically not deployed to greatest effect. This article investigated the alleviation of nursing work stress using resources already extant in coworker social networks. Researchers conducted a survey in a dialysis department at a medical center located in Taipei City, Taiwan. This survey measured nurse work stress, satisfaction, organizational citizenship behavior (OCB) and social network structures. Researchers employed UCINET to analyze the network structure data, which were in dyadic matrix format to estimate nurse network centralities and used partial least squares analysis to estimate research construct path coefficients and test extrapolated hypotheses. The level of OCB induced by nurse social ties was satisfactory and did not only directly increased work satisfaction but also alleviated work stress, which indirectly boosted work satisfaction. Findings suggest that managers may be able to use social network analysis to identify persons appropriate to conduct the distribution of organizational resources. Choosing those with multiple social connections can help distribute resources effectively and induce higher OCB levels within the organization. In addition, staff with strong friendship network connections may provide appropriate psychological resources (support) to coworkers. If those with high friendship network centrality receive proper counseling training, they should be in a good position to provide assistance when needed.

Comparing energy sources for surgical ablation of atrial fibrillation: a Bayesian network meta-analysis of randomized, controlled trials.

PubMed

Phan, Kevin; Xie, Ashleigh; Kumar, Narendra; Wong, Sophia; Medi, Caroline; La Meir, Mark; Yan, Tristan D

2015-08-01

Simplified maze procedures involving radiofrequency, cryoenergy and microwave energy sources have been increasingly utilized for surgical treatment of atrial fibrillation as an alternative to the traditional cut-and-sew approach. In the absence of direct comparisons, a Bayesian network meta-analysis is another alternative to assess the relative effect of different treatments, using indirect evidence. A Bayesian meta-analysis of indirect evidence was performed using 16 published randomized trials identified from 6 databases. Rank probability analysis was used to rank each intervention in terms of their probability of having the best outcome. Sinus rhythm prevalence beyond the 12-month follow-up was similar between the cut-and-sew, microwave and radiofrequency approaches, which were all ranked better than cryoablation (respectively, 39, 36, and 25 vs 1%). The cut-and-sew maze was ranked worst in terms of mortality outcomes compared with microwave, radiofrequency and cryoenergy (2 vs 19, 34, and 24%, respectively). The cut-and-sew maze procedure was associated with significantly lower stroke rates compared with microwave ablation [odds ratio <0.01; 95% confidence interval 0.00, 0.82], and ranked the best in terms of pacemaker requirements compared with microwave, radiofrequency and cryoenergy (81 vs 14, and 1, <0.01% respectively). Bayesian rank probability analysis shows that the cut-and-sew approach is associated with the best outcomes in terms of sinus rhythm prevalence and stroke outcomes, and remains the gold standard approach for AF treatment. Given the limitations of indirect comparison analysis, these results should be viewed with caution and not over-interpreted. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Measuring flood footprint of a regional economy - A case study for the UK flooding

NASA Astrophysics Data System (ADS)

Guan, D.

2013-12-01

Analysis of the urban economy and society is central to understanding the broad impacts of flooding and to identify cost-effective adaptation and mitigation measures. Assessments of the flooding impacts on cities have traditionally focused on the initial impact on people and assets. These initial estimates (so-called ';direct damage') are useful both in understanding the immediate implications of damage, and in marshalling the pools of capital and supplies required for re-building after an event. Since different economies as well as societies are coupled, especially under the current economic crisis, any small-scale damage may be multiplied and cascaded throughout wider economic systems and social networks. The direct and indirect damage is currently not evaluated well and could be captured by quantification of what we call the flood footprint. Flooding in one location can impact the whole UK economy. Neglecting these knock-on costs (i.e. the true footprint of the flood) means we might be ignoring the economic benefits and beneficiaries of flood risk management interventions. In 2007, for example, floods cost the economy about £3.2 bn directly, but the wider effect might actually add another 50% to 250% to that. Flood footprint is a measure of the exclusive total socioeconomic impact that is directly and indirectly caused by a flood event to the flooding region and wider economic systems and social networks. We adopt the UK 2012 flooding. An input-output basic dynamic inequalities (BDI) model is used to assess the impact of the floodings on the level of a Yorkshire economy, accounting for interactions between industries through demand and supply of intermediate consumption goods with a circular flow. After the disaster the economy will be unbalanced. The recovery process finishes when the economy is completely balance, i.e., when labour production capacity equals demands and production and all the variables reach pre-disaster levels. The analysis is carried out focusing on 42 sectors. Most regional data have been produced from the Multisectoral Dynamic Model of the UK economy. The flooding caused a 3.56% direct damage in the Yorkshire economy, while the indirect accounted for 14.58%.Utilities and transportation where the sectors that suffered the greatest direct impact. This impact indirectly transferred through business and supply chain to services, construction and primary industries.

Ontology-based literature mining of E. coli vaccine-associated gene interaction networks.

PubMed

Hur, Junguk; Özgür, Arzucan; He, Yongqun

2017-03-14

Pathogenic Escherichia coli infections cause various diseases in humans and many animal species. However, with extensive E. coli vaccine research, we are still unable to fully protect ourselves against E. coli infections. To more rational development of effective and safe E. coli vaccine, it is important to better understand E. coli vaccine-associated gene interaction networks. In this study, we first extended the Vaccine Ontology (VO) to semantically represent various E. coli vaccines and genes used in the vaccine development. We also normalized E. coli gene names compiled from the annotations of various E. coli strains using a pan-genome-based annotation strategy. The Interaction Network Ontology (INO) includes a hierarchy of various interaction-related keywords useful for literature mining. Using VO, INO, and normalized E. coli gene names, we applied an ontology-based SciMiner literature mining strategy to mine all PubMed abstracts and retrieve E. coli vaccine-associated E. coli gene interactions. Four centrality metrics (i.e., degree, eigenvector, closeness, and betweenness) were calculated for identifying highly ranked genes and interaction types. Using vaccine-related PubMed abstracts, our study identified 11,350 sentences that contain 88 unique INO interactions types and 1,781 unique E. coli genes. Each sentence contained at least one interaction type and two unique E. coli genes. An E. coli gene interaction network of genes and INO interaction types was created. From this big network, a sub-network consisting of 5 E. coli vaccine genes, including carA, carB, fimH, fepA, and vat, and 62 other E. coli genes, and 25 INO interaction types was identified. While many interaction types represent direct interactions between two indicated genes, our study has also shown that many of these retrieved interaction types are indirect in that the two genes participated in the specified interaction process in a required but indirect process. Our centrality analysis of these gene interaction networks identified top ranked E. coli genes and 6 INO interaction types (e.g., regulation and gene expression). Vaccine-related E. coli gene-gene interaction network was constructed using ontology-based literature mining strategy, which identified important E. coli vaccine genes and their interactions with other genes through specific interaction types.

Multiple Linear Regression for Reconstruction of Gene Regulatory Networks in Solving Cascade Error Problems

PubMed Central

Zainudin, Suhaila; Arif, Shereena M.

2017-01-01

Gene regulatory network (GRN) reconstruction is the process of identifying regulatory gene interactions from experimental data through computational analysis. One of the main reasons for the reduced performance of previous GRN methods had been inaccurate prediction of cascade motifs. Cascade error is defined as the wrong prediction of cascade motifs, where an indirect interaction is misinterpreted as a direct interaction. Despite the active research on various GRN prediction methods, the discussion on specific methods to solve problems related to cascade errors is still lacking. In fact, the experiments conducted by the past studies were not specifically geared towards proving the ability of GRN prediction methods in avoiding the occurrences of cascade errors. Hence, this research aims to propose Multiple Linear Regression (MLR) to infer GRN from gene expression data and to avoid wrongly inferring of an indirect interaction (A → B → C) as a direct interaction (A → C). Since the number of observations of the real experiment datasets was far less than the number of predictors, some predictors were eliminated by extracting the random subnetworks from global interaction networks via an established extraction method. In addition, the experiment was extended to assess the effectiveness of MLR in dealing with cascade error by using a novel experimental procedure that had been proposed in this work. The experiment revealed that the number of cascade errors had been very minimal. Apart from that, the Belsley collinearity test proved that multicollinearity did affect the datasets used in this experiment greatly. All the tested subnetworks obtained satisfactory results, with AUROC values above 0.5. PMID:28250767

Vitamin D and gene networks in human osteoblasts

PubMed Central

van de Peppel, Jeroen; van Leeuwen, Johannes P. T. M.

2014-01-01

Bone formation is indirectly influenced by 1,25-dihydroxyvitamin D3 (1,25D3) through the stimulation of calcium uptake in the intestine and re-absorption in the kidneys. Direct effects on osteoblasts and bone formation have also been established. The vitamin D receptor (VDR) is expressed in osteoblasts and 1,25D3 modifies gene expression of various osteoblast differentiation and mineralization-related genes, such as alkaline phosphatase (ALPL), osteocalcin (BGLAP), and osteopontin (SPP1). 1,25D3 is known to stimulate mineralization of human osteoblasts in vitro, and recently it was shown that 1,25D3 induces mineralization via effects in the period preceding mineralization during the pre-mineralization period. For a full understanding of the action of 1,25D3 in osteoblasts it is important to get an integrated network view of the 1,25D3-regulated genes during osteoblast differentiation and mineralization. The current data will be presented and discussed alluding to future studies to fully delineate the 1,25D3 action in osteoblast. Describing and understanding the vitamin D regulatory networks and identifying the dominant players in these networks may help develop novel (personalized) vitamin D-based treatments. The following topics will be discussed in this overview: (1) Bone metabolism and osteoblasts, (2) Vitamin D, bone metabolism and osteoblast function, (3) Vitamin D induced transcriptional networks in the context of osteoblast differentiation and bone formation. PMID:24782782

An Embedded Wireless Sensor Network with Wireless Power Transmission Capability for the Structural Health Monitoring of Reinforced Concrete Structures.

PubMed

Gallucci, Luca; Menna, Costantino; Angrisani, Leopoldo; Asprone, Domenico; Moriello, Rosario Schiano Lo; Bonavolontà, Francesco; Fabbrocino, Francesco

2017-11-07

Maintenance strategies based on structural health monitoring can provide effective support in the optimization of scheduled repair of existing structures, thus enabling their lifetime to be extended. With specific regard to reinforced concrete (RC) structures, the state of the art seems to still be lacking an efficient and cost-effective technique capable of monitoring material properties continuously over the lifetime of a structure. Current solutions can typically only measure the required mechanical variables in an indirect, but economic, manner, or directly, but expensively. Moreover, most of the proposed solutions can only be implemented by means of manual activation, making the monitoring very inefficient and then poorly supported. This paper proposes a structural health monitoring system based on a wireless sensor network (WSN) that enables the automatic monitoring of a complete structure. The network includes wireless distributed sensors embedded in the structure itself, and follows the monitoring-based maintenance (MBM) approach, with its ABCDE paradigm, namely: accuracy, benefit, compactness, durability, and easiness of operations. The system is structured in a node level and has a network architecture that enables all the node data to converge in a central unit. Human control is completely unnecessary until the periodic evaluation of the collected data. Several tests are conducted in order to characterize the system from a metrological point of view and assess its performance and effectiveness in real RC conditions.

Population Fluctuation Promotes Cooperation in Networks

PubMed Central

Miller, Steve; Knowles, Joshua

2015-01-01

We consider the problem of explaining the emergence and evolution of cooperation in dynamic network-structured populations. Building on seminal work by Poncela et al., which shows how cooperation (in one-shot prisoner’s dilemma) is supported in growing populations by an evolutionary preferential attachment (EPA) model, we investigate the effect of fluctuations in the population size. We find that a fluctuating model – based on repeated population growth and truncation – is more robust than Poncela et al.’s in that cooperation flourishes for a wider variety of initial conditions. In terms of both the temptation to defect, and the types of strategies present in the founder network, the fluctuating population is found to lead more securely to cooperation. Further, we find that this model will also support the emergence of cooperation from pre-existing non-cooperative random networks. This model, like Poncela et al.’s, does not require agents to have memory, recognition of other agents, or other cognitive abilities, and so may suggest a more general explanation of the emergence of cooperation in early evolutionary transitions, than mechanisms such as kin selection, direct and indirect reciprocity. PMID:26061705

Networked buffering: a basic mechanism for distributed robustness in complex adaptive systems.

PubMed

Whitacre, James M; Bender, Axel

2010-06-15

A generic mechanism--networked buffering--is proposed for the generation of robust traits in complex systems. It requires two basic conditions to be satisfied: 1) agents are versatile enough to perform more than one single functional role within a system and 2) agents are degenerate, i.e. there exists partial overlap in the functional capabilities of agents. Given these prerequisites, degenerate systems can readily produce a distributed systemic response to local perturbations. Reciprocally, excess resources related to a single function can indirectly support multiple unrelated functions within a degenerate system. In models of genome:proteome mappings for which localized decision-making and modularity of genetic functions are assumed, we verify that such distributed compensatory effects cause enhanced robustness of system traits. The conditions needed for networked buffering to occur are neither demanding nor rare, supporting the conjecture that degeneracy may fundamentally underpin distributed robustness within several biotic and abiotic systems. For instance, networked buffering offers new insights into systems engineering and planning activities that occur under high uncertainty. It may also help explain recent developments in understanding the origins of resilience within complex ecosystems.

White matter lesions relate to tract-specific reductions in functional connectivity.

PubMed

Langen, Carolyn D; Zonneveld, Hazel I; White, Tonya; Huizinga, Wyke; Cremers, Lotte G M; de Groot, Marius; Ikram, Mohammad Arfan; Niessen, Wiro J; Vernooij, Meike W

2017-03-01

White matter lesions play a role in cognitive decline and dementia. One presumed pathway is through disconnection of functional networks. Little is known about location-specific effects of lesions on functional connectivity. This study examined location-specific effects within anatomically-defined white matter tracts in 1584 participants of the Rotterdam Study, aged 50-95. Tracts were delineated from diffusion magnetic resonance images using probabilistic tractography. Lesions were segmented on fluid-attenuated inversion recovery images. Functional connectivity was defined across each tract on resting-state functional magnetic resonance images by using gray matter parcellations corresponding to the tract ends and calculating the correlation of the mean functional activity between the gray matter regions. A significant relationship between both local and brain-wide lesion load and tract-specific functional connectivity was found in several tracts using linear regressions, also after Bonferroni correction. Indirect connectivity analyses revealed that tract-specific functional connectivity is affected by lesions in several tracts simultaneously. These results suggest that local white matter lesions can decrease tract-specific functional connectivity, both in direct and indirect connections. Copyright © 2016 Elsevier Inc. All rights reserved.

Estimating regional long-term economic consequences of natural hazards - a case study of the 2005 flood event in Tyrol (Austria)

NASA Astrophysics Data System (ADS)

Pfurtscheller, C.; Lochner, B.; Brucker, A.

2012-04-01

The interaction of relief-driven alpine natural processes with the anthropogenic sphere often leads to natural disasters which significantly impact on remote alpine economies. When evaluating the effects of such events for future risk prevention strategies, it is essential to assess indirect losses. While the economic measurement of direct effects - the physical impact on structures and infrastructure - seems fairly manageable, less is known about the dimensions of indirect effects, especially on a local and regional scale within the Alps. The lack of standardized terminology, empirical data and methods to estimate indirect economic effects currently hampers profound decision support. In our study of the 2005 flood event in Tyrol, we surveyed companies from all sectors of the economy to identify the main drivers of indirect effects and interrupted economic flows. In collaboration with the Federal State administration, we extrapolate the total regional economic effects of this catastrophic event. Using quantitative and qualitative methods, we established and analysed a data pool of questionnaire and interview results as well as direct loss data. We mainly focus on the decrease in value creation and the negative impacts on tourism. We observed that disrupted traffic networks can have a highly negative impact, especially for the tourism sector in lateral alpine valleys. Within a month, turnover fell by approximately EUR 3.3 million in the investigated area. In the short run (until August 2006), the shortfall in touristic revenues in the Paznaun valley aggregated to approx. EUR 5.3 million. We observed that overnight stays rebound very quickly so that long-term effects are marginal. In addition, we tried to identify possible economical losers as well as winners of severe hazard impacts. In response to such flood events, high investments are made to improve disaster and risk management. Nearly 70% of the respondents specified the (re)construction sector and similar businesses as main beneficiaries and about 40% mentioned infrastructural improvements, as in streets or protective measures, as the most positive effect. We present an empirical approach to assess the economic consequences of fatal events and provide rules of thumb to quickly estimate indirect economic losses from natural disasters, at least for the Alpine Space, at the local and regional level. The methods and results of this study can help to improve ex-post loss estimations, and with it, ex-ante methods for the cost efficiency of risk reduction measures, e.g. cost-benefit-analysis.

High-resolution electron microscope observation of voids in amorphous Ge.

NASA Technical Reports Server (NTRS)

Donovan, T. M.; Heinemann, K.

1971-01-01

Electron micrographs have been obtained which clearly show the existence of a void network in amorphous Ge films formed at substrate temperatures of 25 and 150 C, and the absence of a void network in films formed at higher substrate temperatures of 200 and 250 C. These results correlate quite well with density measurements and predictions of void densities by indirect methods.

Influence Operations: Redefining the Indirect Approach

DTIC Science & Technology

2011-06-01

companies with JI teachers and preachers to disseminate messages: But the most successful distribution may be by word of mouth . As soon as a book is...unlimited 12b. DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words ) Across today’s spectrum of contemporary warfare, the human terrain is routinely...indoctrination, and electronic social networks (eSocial networks). Hezbollah and Al Qaeda continue to exemplify these methods. From Indonesia to

Issues connected with indirect cost quantification: a focus on the transportation system

NASA Astrophysics Data System (ADS)

Křivánková, Zuzana; Bíl, Michal; Kubeček, Jan; Vodák, Rostislav

2017-04-01

Transportation and communication networks in general are vital parts of modern society. The economy relies heavily on transportation system performance. A number of people commutes to work regularly. Stockpiles in many companies are being reduced as the just-in-time production process is able to supply resources via the transportation network on time. Natural hazards have the potential to disturb transportation systems. Earthquakes, flooding or landsliding are examples of high-energetic processes which are capable of causing direct losses (i.e. physical damage to the infrastructure). We have focused on quantification of the indirect cost of natural hazards which are not easy to estimate. Indirect losses can also emerge as a result of meteorological hazards with low energy which only seldom cause direct losses, e.g. glaze, snowfall. Whereas evidence of repair work and general direct costs usually exist or can be estimated, indirect costs are much more difficult to identify particularly when they are not covered by insurance agencies. Delimitations of alternative routes (detours) are the most frequent responses to blocked road links. Indirect costs can then be related to increased fuel consumption and additional operating costs. Detours usually result in prolonged travel times. Indirect costs quantification has to therefore cover the value of the time. The costs from the delay are a nonlinear function of travel time, however. The existence of an alternative transportation pattern may also result in an increased number of traffic crashes. This topic has not been studied in depth but an increase in traffic crashes has been reported when people suddenly changed their traffic modes, e.g. when air traffic was not possible. The lost user benefit from those trips that were cancelled or suppressed is also difficult to quantify. Several approaches, based on post-event questioner surveys, have been applied to communities and companies affected by transportation accessibility cut-off. No widely accepted methodology is available, however. In this presentation we will discuss current approaches, and their limitations related to indirect cost estimation which can be applied to estimation of natural hazard impacts.

Road networks predict human influence on Amazonian bird communities.

PubMed

Ahmed, Sadia E; Lees, Alexander C; Moura, Nárgila G; Gardner, Toby A; Barlow, Jos; Ferreira, Joice; Ewers, Robert M

2014-11-22

Road building can lead to significant deleterious impacts on biodiversity, varying from direct road-kill mortality and direct habitat loss associated with road construction, to more subtle indirect impacts from edge effects and fragmentation. However, little work has been done to evaluate the specific effects of road networks and biodiversity loss beyond the more generalized effects of habitat loss. Here, we compared forest bird species richness and composition in the municipalities of Santarém and Belterra in Pará state, eastern Brazilian Amazon, with a road network metric called 'roadless volume (RV)' at the scale of small hydrological catchments (averaging 3721 ha). We found a significant positive relationship between RV and both forest bird richness and the average number of unique species (species represented by a single record) recorded at each site. Forest bird community composition was also significantly affected by RV. Moreover, there was no significant correlation between RV and forest cover, suggesting that road networks may impact biodiversity independently of changes in forest cover. However, variance partitioning analysis indicated that RV has partially independent and therefore additive effects, suggesting that RV and forest cover are best used in a complementary manner to investigate changes in biodiversity. Road impacts on avian species richness and composition independent of habitat loss may result from road-dependent habitat disturbance and fragmentation effects that are not captured by total percentage habitat cover, such as selective logging, fire, hunting, traffic disturbance, edge effects and road-induced fragmentation. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

From loss to loneliness: The relationship between bereavement and depressive symptoms.

PubMed

Fried, Eiko I; Bockting, Claudi; Arjadi, Retha; Borsboom, Denny; Amshoff, Maximilian; Cramer, Angélique O J; Epskamp, Sacha; Tuerlinckx, Francis; Carr, Deborah; Stroebe, Margaret

2015-05-01

Spousal bereavement can cause a rise in depressive symptoms. This study empirically evaluates 2 competing explanations concerning how this causal effect is brought about: (a) a traditional latent variable explanation, in which loss triggers depression which then leads to symptoms; and (b) a novel network explanation, in which bereavement directly affects particular depression symptoms which then activate other symptoms. We used data from the Changing Lives of Older Couples (CLOC) study and compared depressive symptomatology, assessed via the 11-item Center for Epidemiologic Studies Depression Scale (CES-D), among those who lost their partner (N = 241) with a still-married control group (N = 274). We modeled the effect of partner loss on depressive symptoms either as an indirect effect through a latent variable, or as a direct effect in a network constructed through a causal search algorithm. Compared to the control group, widow(er)s' scores were significantly higher for symptoms of loneliness, sadness, depressed mood, and appetite loss, and significantly lower for happiness and enjoyed life. The effect of partner loss on these symptoms was not mediated by a latent variable. The network model indicated that bereavement mainly affected loneliness, which in turn activated other depressive symptoms. The direct effects of spousal loss on particular symptoms are inconsistent with the predictions of latent variable models, but can be explained from a network perspective. The findings support a growing body of literature showing that specific adverse life events differentially affect depressive symptomatology, and suggest that future studies should examine interventions that directly target such symptoms. (c) 2015 APA, all rights reserved).

Dopaminergic modulation of semantic priming in healthy volunteers.

PubMed

Roesch-Ely, Daniela; Weiland, Stephan; Scheffel, Hans; Schwaninger, Markus; Hundemer, Hans-Peter; Kolter, Thomas; Weisbrod, Matthias

2006-09-15

Semantic priming is a function related to prefrontal cortical (PFC) networks and is lateralized. There is evidence that semantic priming underlies dopaminergic modulation. It is known that the D1-receptor is more abundant in prefrontal networks; however, until now there have been no studies investigating the selective modulation of semantic priming with dopamine agonists. Furthermore, D1 receptor dysfunction has been described in schizophrenia, and patients with formal thought disorder seem to have disturbed focusing of associations and increased indirect priming. With a subtraction design, we compared the influence of pergolide (D1/D2 agonist) with bromocriptine (D2 agonist) and placebo, in a randomized, double-blind, crossover design in 40 healthy male volunteers. Subjects performed a lateralized lexical decision task including direct and indirect related prime-target pairs (stimulus onset asynchrony = 750 msec). Only on pergolide a decrease of the indirect priming in the left hemisphere presentations was found. These findings point to a potential selective modulation of agonists with a D1 component on the focusing of semantic associations. The clinical relevance of this study is that it might help the development of therapeutic strategies for treating cognitive deficits in schizophrenia and Parkinson's disease, which are highly relevant to the functional outcome.

Modelling fast spreading patterns of airborne infectious diseases using complex networks

NASA Astrophysics Data System (ADS)

Brenner, Frank; Marwan, Norbert; Hoffmann, Peter

2017-04-01

The pandemics of SARS (2002/2003) and H1N1 (2009) have impressively shown the potential of epidemic outbreaks of infectious diseases in a world that is strongly connected. Global air travelling established an easy and fast opportunity for pathogens to migrate globally in only a few days. This made epidemiological prediction harder. By understanding this complex development and its link to climate change we can suggest actions to control a part of global human health affairs. In this study we combine the following data components to simulate the outbreak of an airborne infectious disease that is directly transmitted from human to human: em{Global Air Traffic Network (from openflights.org) with information on airports, airport location, direct flight connection, airplane type} em{Global population dataset (from SEDAC, NASA)} em{Susceptible-Infected-Recovered (SIR) compartmental model to simulate disease spreading in the vicinity of airports. A modified Susceptible-Exposed-Infected-Recovered (SEIR) model to analyze the impact of the incubation period.} em{WATCH-Forcing-Data-ERA-Interim (WFDEI) climate data: temperature, specific humidity, surface air pressure, and water vapor pressure} These elements are implemented into a complex network. Nodes inside the network represent airports. Each single node is equipped with its own SIR/SEIR compartmental model with node specific attributes. Edges between those nodes represent direct flight connections that allow infected individuals to move between linked nodes. Therefore the interaction of the set of unique SIR models creates the model dynamics we will analyze. To better figure out the influence on climate change on disease spreading patterns, we focus on Influenza-like-Illnesses (ILI). The transmission rate of ILI has a dependency on climate parameters like humidity and temperature. Even small changes of environmental variables can trigger significant differences in the global outbreak behavior. Apart from the direct effect of climate change on the transmission of airborne diseases, there are indirect ramifications that alter spreading patterns. An example is seasonal human mobility behavior which will change with varied climate conditions. The direct and indirect effects of climate change on disease spreading patterns will be discussed in this study.

Active Self-Testing Noise Measurement Sensors for Large-Scale Environmental Sensor Networks

PubMed Central

Domínguez, Federico; Cuong, Nguyen The; Reinoso, Felipe; Touhafi, Abdellah; Steenhaut, Kris

2013-01-01

Large-scale noise pollution sensor networks consist of hundreds of spatially distributed microphones that measure environmental noise. These networks provide historical and real-time environmental data to citizens and decision makers and are therefore a key technology to steer environmental policy. However, the high cost of certified environmental microphone sensors render large-scale environmental networks prohibitively expensive. Several environmental network projects have started using off-the-shelf low-cost microphone sensors to reduce their costs, but these sensors have higher failure rates and produce lower quality data. To offset this disadvantage, we developed a low-cost noise sensor that actively checks its condition and indirectly the integrity of the data it produces. The main design concept is to embed a 13 mm speaker in the noise sensor casing and, by regularly scheduling a frequency sweep, estimate the evolution of the microphone's frequency response over time. This paper presents our noise sensor's hardware and software design together with the results of a test deployment in a large-scale environmental network in Belgium. Our middle-range-value sensor (around €50) effectively detected all experienced malfunctions, in laboratory tests and outdoor deployments, with a few false positives. Future improvements could further lower the cost of our sensor below €10. PMID:24351634

Evaluating effects of methylphenidate on brain activity in cocaine addiction: a machine-learning approach

NASA Astrophysics Data System (ADS)

Rish, Irina; Bashivan, Pouya; Cecchi, Guillermo A.; Goldstein, Rita Z.

2016-03-01

The objective of this study is to investigate effects of methylphenidate on brain activity in individuals with cocaine use disorder (CUD) using functional MRI (fMRI). Methylphenidate hydrochloride (MPH) is an indirect dopamine agonist commonly used for treating attention deficit/hyperactivity disorders; it was also shown to have some positive effects on CUD subjects, such as improved stop signal reaction times associated with better control/inhibition,1 as well as normalized task-related brain activity2 and resting-state functional connectivity in specific areas.3 While prior fMRI studies of MPH in CUDs have focused on mass-univariate statistical hypothesis testing, this paper evaluates multivariate, whole-brain effects of MPH as captured by the generalization (prediction) accuracy of different classification techniques applied to features extracted from resting-state functional networks (e.g., node degrees). Our multivariate predictive results based on resting-state data from3 suggest that MPH tends to normalize network properties such as voxel degrees in CUD subjects, thus providing additional evidence for potential benefits of MPH in treating cocaine addiction.

Extending natural hazard impacts: an assessment of landslide disruptions on a national road transportation network

NASA Astrophysics Data System (ADS)

Postance, Benjamin; Hillier, John; Dijkstra, Tom; Dixon, Neil

2017-01-01

Disruptions to transportation networks by natural hazard events cause direct losses (e.g. by physical damage) and indirect socio-economic losses via travel delays and decreased transportation efficiency. The severity and spatial distribution of these losses varies according to user travel demands and which links, nodes or infrastructure assets are physically disrupted. Increasing transport network resilience, for example by targeted mitigation strategies, requires the identification of the critical network segments which if disrupted would incur undesirable or unacceptable socio-economic impacts. Here, these impacts are assessed on a national road transportation network by coupling hazard data with a transport network model. This process is illustrated using a case study of landslide hazards on the road network of Scotland. A set of possible landslide-prone road segments is generated using landslide susceptibility data. The results indicate that at least 152 road segments are susceptible to landslides, which could cause indirect economic losses exceeding £35 k for each day of closure. In addition, previous estimates for historic landslide events might be significant underestimates. For example, the estimated losses for the 2007 A83 ‘Rest and Be Thankful’ landslide are £80 k day-1, totalling £1.2 million over a 15 day closure, and are ˜60% greater than previous estimates. The spatial distribution of impact to road users is communicated in terms of ‘extended hazard impact footprints’. These footprints reveal previously unknown exposed communities and unanticipated spatial patterns of severe disruption. Beyond cost-benefit analyses for landslide mitigation efforts, the approach implemented is applicable to other natural hazards (e.g. flooding), combinations of hazards, or even other network disruption events.

The Minicommunity Design to Assess Indirect Effects of Vaccination.

PubMed

Halloran, M Elizabeth

2012-08-01

We propose the minicommunity design to estimate indirect effects of vaccination. Establishing indirect effects of vaccination in unvaccinated subpopulations could have important implications for global vaccine policies. In the minicommunity design, the household or other small transmission unit serves as the cluster in which to estimate indirect effects of vaccination, similar to studies in larger communities to estimate indirect, total, and overall effects. Examples from the literature include studies in small transmission units to estimate indirect effects of pertussis, pneumococcal, influenza, and cholera vaccines. We characterize the minicommunity design by several methodologic considerations, including the assignment mechanism, ascertainment, the role of transmission outside the transmission unit, and the relation of the size of the transmission unit to number of people vaccinated. The minicommunity study for indirect effects is contrasted with studies to estimate vaccine effects on infectiousness and protective effects under conditions of household exposure within small transmission units. The minicommunity design can be easily implemented in individually randomized studies by enrolling and following-up members of households of the randomized individuals. The methodology for the minicommunity design for estimating indirect effects of vaccination deserves much future research.

A process for assessing the feasibility of a network meta-analysis: a case study of everolimus in combination with hormonal therapy versus chemotherapy for advanced breast cancer.

PubMed

Cope, Shannon; Zhang, Jie; Saletan, Stephen; Smiechowski, Brielan; Jansen, Jeroen P; Schmid, Peter

2014-06-05

The aim of this study is to outline a general process for assessing the feasibility of performing a valid network meta-analysis (NMA) of randomized controlled trials (RCTs) to synthesize direct and indirect evidence for alternative treatments for a specific disease population. Several steps to assess the feasibility of an NMA are proposed based on existing recommendations. Next, a case study is used to illustrate this NMA feasibility assessment process in order to compare everolimus in combination with hormonal therapy to alternative chemotherapies in terms of progression-free survival for women with advanced breast cancer. A general process for assessing the feasibility of an NMA is outlined that incorporates explicit steps to visualize the heterogeneity in terms of treatment and outcome characteristics (Part A) as well as the study and patient characteristics (Part B). Additionally, steps are performed to illustrate differences within and across different types of direct comparisons in terms of baseline risk (Part C) and observed treatment effects (Part D) since there is a risk that the treatment effect modifiers identified may not explain the observed heterogeneity or inconsistency in the results due to unexpected, unreported or unmeasured differences. Depending on the data available, alternative approaches are suggested: list assumptions, perform a meta-regression analysis, subgroup analysis, sensitivity analyses, or summarize why an NMA is not feasible. The process outlined to assess the feasibility of an NMA provides a stepwise framework that will help to ensure that the underlying assumptions are systematically explored and that the risks (and benefits) of pooling and indirectly comparing treatment effects from RCTs for a particular research question are transparent.

Characterizing the Spatial and Temporal Distribution of Aerosol Optical Thickness Over the Atlantic Basin Utilizing GOES-8 Multispectral Data

NASA Technical Reports Server (NTRS)

Fox, Robert; Prins, Elaine Mae; Feltz, Joleen M.

2001-01-01

In recent years, modeling and analysis efforts have suggested that the direct and indirect radiative effects of both anthropogenic and natural aerosols play a major role in the radiative balance of the earth and are an important factor in climate change calculations. The direct effects of aerosols on radiation and indirect effects on cloud properties are not well understood at this time. In order to improve the characterization of aerosols within climate models it is important to accurately parameterize aerosol forcing mechanisms at the local, regional, and global scales. This includes gaining information on the spatial and temporal distribution of aerosols, transport regimes and mechanisms, aerosol optical thickness, and size distributions. Although there is an expanding global network of ground measurements of aerosol optical thickness and size distribution at specific locations, satellite data must be utilized to characterize the spatial and temporal extent of aerosols and transport regimes on regional and global scales. This study was part of a collaborative effort to characterize aerosol radiative forcing over the Atlantic basin associated with the following three major aerosol components in this region: urban/sulfate, Saharan dust, and biomass burning. In-situ ground measurements obtained by a network of sun photometers during the Smoke Clouds and Radiation Experiment in Brazil (SCAR-B) and the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) were utilized to develop, calibrate, and validate a Geostationary Operational Environmental Satellite (GOES)-8 aerosol optical thickness (AOT) product. Regional implementation of the GOES-8 AOT product was used to augment point source measurements to gain a better understanding of the spatial and temporal distributions of Atlantic basin aerosols during SCAR-B and TARFOX.

Risk factors and mediating pathways of loneliness and social support in community-dwelling older adults.

PubMed

Schnittger, Rebecca I B; Wherton, Joseph; Prendergast, David; Lawlor, Brian A

2012-01-01

To develop biopsychosocial models of loneliness and social support thereby identifying their key risk factors in an Irish sample of community-dwelling older adults. Additionally, to investigate indirect effects of social support on loneliness through mediating risk factors. A total of 579 participants (400 females; 179 males) were given a battery of biopsychosocial assessments with the primary measures being the De Jong Gierveld Loneliness Scale and the Lubben Social Network Scale along with a broad range of secondary measures. Bivariate correlation analyses identified items to be included in separate psychosocial, cognitive, biological and demographic multiple regression analyses. The resulting model items were then entered into further multiple regression analyses to obtain overall models. Following this, bootstrapping mediation analyses was conducted to examine indirect effects of social support on the subtypes (emotional and social) of loneliness. The overall model for (1) emotional loneliness included depression, neuroticism, perceived stress, living alone and accommodation type, (2) social loneliness included neuroticism, perceived stress, animal naming and number of grandchildren and (3) social support included extraversion, executive functioning (Trail Making Test B-time), history of falls, age and whether the participant drives or not. Social support influenced emotional loneliness predominantly through indirect means, while its effect on social loneliness was more direct. These results characterise the biopsychosocial risk factors of emotional loneliness, social loneliness and social support and identify key pathways by which social support influences emotional and social loneliness. These findings highlight issues with the potential for consideration in the development of targeted interventions.

Age Related Changes in Topological Properties of Brain Functional Network and Structural Connectivity.

PubMed

Shah, Chandan; Liu, Jia; Lv, Peilin; Sun, Huaiqiang; Xiao, Yuan; Liu, Jieke; Zhao, Youjin; Zhang, Wenjing; Yao, Li; Gong, Qiyong; Lui, Su

2018-01-01

Introduction: There are still uncertainties about the true nature of age related changes in topological properties of the brain functional network and its structural connectivity during various developmental stages. In this cross- sectional study, we investigated the effects of age and its relationship with regional nodal properties of the functional brain network and white matter integrity. Method: DTI and fMRI data were acquired from 458 healthy Chinese participants ranging from age 8 to 81 years. Tractography was conducted on the DTI data using FSL. Graph Theory analyses were conducted on the functional data yielding topological properties of the functional network using SPM and GRETNA toolbox. Two multiple regressions were performed to investigate the effects of age on nodal topological properties of the functional brain network and white matter integrity. Result: For the functional studies, we observed that regional nodal characteristics such as node betweenness were decreased while node degree and node efficiency was increased in relation to increasing age. Perversely, we observed that the relationship between nodal topological properties and fasciculus structures were primarily positive for nodal betweenness but negative for nodal degree and nodal efficiency. Decrease in functional nodal betweenness was primarily located in superior frontal lobe, right occipital lobe and the global hubs. These brain regions also had both direct and indirect anatomical relationships with the 14 fiber bundles. A linear age related decreases in the Fractional anisotropy (FA) value was found in the callosum forceps minor. Conclusion: These results suggests that age related differences were more pronounced in the functional than in structural measure indicating these measures do not have direct one-to-one mapping. Our study also indicates that the fiber bundles with longer fibers exhibited a more pronounced effect on the properties of functional network.

Are Nested Networks More Robust to Disturbance? A Test Using Epiphyte-Tree, Comensalistic Networks

PubMed Central

Piazzon, Martín; Larrinaga, Asier R.; Santamaría, Luis

2011-01-01

Recent research on ecological networks suggests that mutualistic networks are more nested than antagonistic ones and, as a result, they are more robust against chains of extinctions caused by disturbances. We evaluate whether mutualistic networks are more nested than comensalistic and antagonistic networks, and whether highly nested, host-epiphyte comensalistic networks fit the prediction of high robustness against disturbance. A review of 59 networks including mutualistic, antagonistic and comensalistic relationships showed that comensalistic networks are significantly more nested than antagonistic and mutualistic networks, which did not differ between themselves. Epiphyte-host networks from old-growth forests differed from those from disturbed forest in several topological parameters based on both qualitative and quantitative matrices. Network robustness increased with network size, but the slope of this relationship varied with nestedness and connectance. Our results indicate that interaction networks show complex responses to disturbances, which influence their topology and indirectly affect their robustness against species extinctions. PMID:21589931

Functional traits help predict post-disturbance demography of tropical trees.

PubMed

Flores, Olivier; Hérault, Bruno; Delcamp, Matthieu; Garnier, Éric; Gourlet-Fleury, Sylvie

2014-01-01

How tropical tree species respond to disturbance is a central issue of forest ecology, conservation and resource management. We define a hierarchical model to investigate how functional traits measured in control plots relate to the population change rate and to demographic rates for recruitment and mortality after disturbance by logging operations. Population change and demographic rates were quantified on a 12-year period after disturbance and related to seven functional traits measured in control plots. The model was calibrated using a Bayesian Network approach on 53 species surveyed in permanent forest plots (37.5 ha) at Paracou in French Guiana. The network analysis allowed us to highlight both direct and indirect relationships among predictive variables. Overall, 89% of interspecific variability in the population change rate after disturbance were explained by the two demographic rates, the recruitment rate being the most explicative variable. Three direct drivers explained 45% of the variability in recruitment rates, including leaf phosphorus concentration, with a positive effect, and seed size and wood density with negative effects. Mortality rates were explained by interspecific variability in maximum diameter only (25%). Wood density, leaf nitrogen concentration, maximum diameter and seed size were not explained by variables in the analysis and thus appear as independent drivers of post-disturbance demography. Relationships between functional traits and demographic parameters were consistent with results found in undisturbed forests. Functional traits measured in control conditions can thus help predict the fate of tropical tree species after disturbance. Indirect relationships also suggest how different processes interact to mediate species demographic response.

The Role of Attachment Style in Facebook Use and Social Capital: Evidence from University Students and a National Sample

PubMed Central

2015-01-01

Abstract Social networking sites (SNSs) can be beneficial tools for users to gain social capital. Although social capital consists of emotional and informational resources accumulated through interactions with strong or weak social network ties, the existing literature largely ignores attachment style in this context. This study employed attachment theory to explore individuals' attachment orientations toward Facebook usage and toward online and offline social capital. A university student sample (study 1) and a representative national sample (study 2) showed consistent results. Secure attachment was positively associated with online bonding and bridging capital and offline bridging capital. Additionally, secure attachment had an indirect effect on all capital through Facebook time. Avoidant attachment was negatively associated with online bonding capital. Anxious–ambivalent attachment had a direct association with online bonding capital and an indirect effect on all capital through Facebook. Interaction frequency with good friends on Facebook positively predicted all online and offline capital, whereas interaction frequency with average friends on Facebook positively predicted online bridging capital. Interaction frequency with acquaintances on Facebook was negatively associated with offline bonding capital. The study concludes that attachment style is a significant factor in guiding social orientation toward Facebook connections with different ties and influences online social capital. The study extends attachment theory among university students to a national sample to provide more generalizable evidence for the current literature. Additionally, this study extends attachment theory to the SNS setting with a nuanced examination of types of Facebook friends after controlling extraversion. Implications for future research are discussed. PMID:25751049

The role of attachment style in Facebook use and social capital: evidence from university students and a national sample.

PubMed

Lin, Jih-Hsuan

2015-03-01

Social networking sites (SNSs) can be beneficial tools for users to gain social capital. Although social capital consists of emotional and informational resources accumulated through interactions with strong or weak social network ties, the existing literature largely ignores attachment style in this context. This study employed attachment theory to explore individuals' attachment orientations toward Facebook usage and toward online and offline social capital. A university student sample (study 1) and a representative national sample (study 2) showed consistent results. Secure attachment was positively associated with online bonding and bridging capital and offline bridging capital. Additionally, secure attachment had an indirect effect on all capital through Facebook time. Avoidant attachment was negatively associated with online bonding capital. Anxious-ambivalent attachment had a direct association with online bonding capital and an indirect effect on all capital through Facebook. Interaction frequency with good friends on Facebook positively predicted all online and offline capital, whereas interaction frequency with average friends on Facebook positively predicted online bridging capital. Interaction frequency with acquaintances on Facebook was negatively associated with offline bonding capital. The study concludes that attachment style is a significant factor in guiding social orientation toward Facebook connections with different ties and influences online social capital. The study extends attachment theory among university students to a national sample to provide more generalizable evidence for the current literature. Additionally, this study extends attachment theory to the SNS setting with a nuanced examination of types of Facebook friends after controlling extraversion. Implications for future research are discussed.

Independently evolved virulence effectors converge onto hubs in a plant immune system network.

PubMed

Mukhtar, M Shahid; Carvunis, Anne-Ruxandra; Dreze, Matija; Epple, Petra; Steinbrenner, Jens; Moore, Jonathan; Tasan, Murat; Galli, Mary; Hao, Tong; Nishimura, Marc T; Pevzner, Samuel J; Donovan, Susan E; Ghamsari, Lila; Santhanam, Balaji; Romero, Viviana; Poulin, Matthew M; Gebreab, Fana; Gutierrez, Bryan J; Tam, Stanley; Monachello, Dario; Boxem, Mike; Harbort, Christopher J; McDonald, Nathan; Gai, Lantian; Chen, Huaming; He, Yijian; Vandenhaute, Jean; Roth, Frederick P; Hill, David E; Ecker, Joseph R; Vidal, Marc; Beynon, Jim; Braun, Pascal; Dangl, Jeffery L

2011-07-29

Plants generate effective responses to infection by recognizing both conserved and variable pathogen-encoded molecules. Pathogens deploy virulence effector proteins into host cells, where they interact physically with host proteins to modulate defense. We generated an interaction network of plant-pathogen effectors from two pathogens spanning the eukaryote-eubacteria divergence, three classes of Arabidopsis immune system proteins, and ~8000 other Arabidopsis proteins. We noted convergence of effectors onto highly interconnected host proteins and indirect, rather than direct, connections between effectors and plant immune receptors. We demonstrated plant immune system functions for 15 of 17 tested host proteins that interact with effectors from both pathogens. Thus, pathogens from different kingdoms deploy independently evolved virulence proteins that interact with a limited set of highly connected cellular hubs to facilitate their diverse life-cycle strategies.

Physical aging of linear and network epoxy resins

NASA Technical Reports Server (NTRS)

Kong, E. S.-W.; Wilkes, G. L.; Mcgrath, J. E.; Banthia, A. K.; Mohajer, Y.; Tant, M. R.

1981-01-01

Network and linear epoxy resins principally based on the diglycidyl ether of bisphenol-A and its oligomers are prepared and studied using diamine and anhydride crosslinking agents. Rubber modified epoxies and a carbon fiber reinforced composite are also investigated. All materials display time-dependent changes when stored at temperatures below the glass transition temperature after quenching (sub-T/g/ annealing). Solvent sorption experiments initiated after different sub-T(g) annealing times demonstrate that the rate of solvent uptake can be indirectly related to the free volume of the epoxy resins. Residual thermal stresses and water are found to have little effect on the physical aging process, which affects the sub-T(g) properties of uniaxial carbon fiber reinforced epoxy material. Finally, the importance of the recovery phenomenon which affects the durability of epoxy glasses is considered.

Dynamics of Fractal Cluster Gels with Embedded Active Colloids

NASA Astrophysics Data System (ADS)

Szakasits, Megan E.; Zhang, Wenxuan; Solomon, Michael J.

2017-08-01

We find that embedded active colloids increase the ensemble-averaged mean squared displacement of particles in otherwise passively fluctuating fractal cluster gels. The enhancement in dynamics occurs by a mechanism in which the active colloids contribute to the average dynamics both directly through their own active motion and indirectly through their excitation of neighboring passive colloids in the fractal network. Fractal cluster gels are synthesized by addition of magnesium chloride to an initially stable suspension of 1.0 μ m polystyrene colloids in which a dilute concentration of platinum coated Janus colloids has been dispersed. The Janus colloids are thereby incorporated into the fractal network. We measure the ensemble-averaged mean squared displacement of all colloids in the gel before and after the addition of hydrogen peroxide, a fuel that drives diffusiophoretic motion of the Janus particles. The gel mean squared displacement increases by up to a factor of 3 for an active to passive particle ratio of 1 ∶20 and inputted active energy—defined based on the hydrogen peroxide's effect on colloid swim speed and run length—that is up to 9.5 times thermal energy, on a per particle basis. We model the enhancement in gel particle dynamics as the sum of a direct contribution from the displacement of the Janus particles themselves and an indirect contribution from the strain field that the active colloids induce in the surrounding passive particles.

Effects of Social Support About Physical Activity on Social Networking Sites: Applying the Theory of Planned Behavior.

PubMed

Zhang, Ni; Campo, Shelly; Yang, Jingzhen; Janz, Kathleen F; Snetselaar, Linda G; Eckler, Petya

2015-01-01

Despite the physical and mental health benefits of leisure-time physical activity (LTPA), only about half of college students participate in the recommended amount of LTPA. While college students are avid users of social network sites (SNSs), whether SNSs would be an effective channel for promoting LTPA through peer social support is unclear. The aim of this study was to explore the effects of social support from students' contacts on SNSs on their intention to participate in LTPA, applying the Theory of Planned Behavior. Participants were recruited through a mass e-mail sent to undergraduate students at a large Midwestern university in fall 2011. In total, 439 surveys were analyzed. Descriptive analyses and analysis for mediating effects were conducted. Social support about LTPA from contacts on SNSs has indirect effect on intention through affective attitude, instrumental attitude, and perceived behavioral control (PBC). The results indicate that social support about LTPA from contacts on SNSs might not be effective to change students' intention unless attitudes and PBC are changed. Future interventions aiming to promote students' intention to participate in LTPA by increasing support from contacts on SNSs should increase affective attitude, instrumental attitude, and PBC at the same time.

Food web modeling of a river ecosystem for risk assessment of down-the-drain chemicals: a case study with AQUATOX.

PubMed

Lombardo, Andrea; Franco, Antonio; Pivato, Alberto; Barausse, Alberto

2015-03-01

Conventional approaches to estimating protective ecotoxicological thresholds of chemicals, i.e. predicted no-effect concentrations (PNEC), for an entire ecosystem are based on the use of assessment factors to extrapolate from single-species toxicity data derived in the laboratory to community-level effects on ecosystems. Aquatic food web models may be a useful tool to improve the ecological realism of chemical risk assessment because they enable a more insightful evaluation of the fate and effects of chemicals in dynamic trophic networks. A case study was developed in AQUATOX to simulate the effects of the anionic surfactant linear alkylbenzene sulfonate and the antimicrobial triclosan on a lowland riverine ecosystem. The model was built for a section of the River Thames (UK), for which detailed ecological surveys were available, allowing for a quantification of energy flows through the whole ecosystem. A control scenario was successfully calibrated for a simulation period of one year, and tested for stability over six years. Then, the model ecosystem was perturbed with varying inputs of the two chemicals. Simulations showed that both chemicals rapidly approach steady-state, with internal concentrations in line with the input bioconcentration factors throughout the year. At realistic environmental concentrations, both chemicals have insignificant effects on biomass trends. At hypothetical higher concentrations, direct and indirect effects of chemicals on the ecosystem dynamics emerged from the simulations. Indirect effects due to competition for food sources and predation can lead to responses in biomass density of the same magnitude as those caused by direct toxicity. Indirect effects can both exacerbate or compensate for direct toxicity. Uncertainties in key model assumptions are high as the validation of perturbed simulations remains extremely challenging. Nevertheless, the study is a step towards the development of realistic ecological scenarios and their potential use in prospective risk assessment of down-the-drain chemicals. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of DEM resolution on rainfall-triggered landslide modeling within a triangulated network-based model. A case study in the Luquillo Forest, Puerto Rico

NASA Astrophysics Data System (ADS)

Arnone, E.; Dialynas, Y. G.; Noto, L. V.; Bras, R. L.

2013-12-01

Catchment slope distribution is one of the topographic characteristics that significantly control rainfall-triggered landslide modeling, in both direct and indirect ways. Slope directly determines the soil volume associated with instability. Indirectly slope also affects the subsurface lateral redistribution of soil moisture across the basin, which in turn determines the water pore pressure conditions that impact slope stability. In this study, we investigate the influence of DEM resolution on slope stability and the slope stability analysis by using a distributed eco-hydrological and landslide model, the tRIBS-VEGGIE (Triangulated Irregular Network (TIN)-based Real-time Integrated Basin Simulator - VEGetation Generator for Interactive Evolution). The model implements a triangulated irregular network to describe the topography, and it is capable of evaluating vegetation dynamics and predicting shallow landslides triggered by rainfall. The impact of DEM resolution on the landslide prediction was studied using five TINs derived from five grid DEMs at different resolutions, i.e. 10, 20, 30, 50 and 70 m respectively. The analysis was carried out on the Mameyes Basin, located in the Luquillo Experimental Forest in Puerto Rico, where previous landslide analyses have been carried out. Results showed that the use of the irregular mesh reduced the loss of accuracy in the derived slope distribution when coarser resolutions were used. The impact of the different resolutions on soil moisture patterns was important only when the lateral redistribution was considerable, depending on hydrological properties and rainfall forcing. In some cases, the use of different DEM resolutions did not significantly affect tRIBS-VEGGIE landslide output, in terms of landslide locations, and values of slope and soil moisture at failure.

RUPOK - a web-map application for assessment of impacts of natural hazards on the transportation infrastructure

NASA Astrophysics Data System (ADS)

Bíl, Michal; Kubeček, Jan; Andrášik, Richard; Bílová, Martina; Sedoník, Jiří

2016-04-01

We present a web-map application (www.rupok.cz) designed for visualization of losses caused by natural hazards to the transportation infrastructure. This application is an output of a project in which we analyzed direct, indirect and network-wide impacts of major natural disasters which hit the CZ as of 1997. When natural disasters hit a road network the results are often a number of closed road sections. Certain roads may be, however, destroyed, whereas the majority of them are usually only closed and can be reopened after a short period of time. While the computation of direct losses (the cost of remedial works) is fairly simple, the evaluation of indirect and network-wide costs is much more difficult. We created a database of interrupted road and highway sections due to natural processes which includes data since 1997 and which is automatically updated. 6,828 records concerning interrupted communications located on 2,879 road sections are included in the database for the 1997 - 2014 time period. Flooding caused 37 % of the traffic interruptions, followed by fallen trees (22 %), landsliding (5 %) and rockfalls (2 %). The RUPOK webpage contains information on the probabilities of transportation section interruptions due to natural processes as well as the impacts of possible interruptions. The direct losses are depicted as monetary values per road section unit. The values are calculated on the basis of official tables including the prices for construction works. The indirect losses were calculated on the basis of the best alternative route expenses and as traffic intensities affected by a road section interruption.

Conceptualizing and Testing Random Indirect Effects and Moderated Mediation in Multilevel Models: New Procedures and Recommendations

ERIC Educational Resources Information Center

Bauer, Daniel J.; Preacher, Kristopher J.; Gil, Karen M.

2006-01-01

The authors propose new procedures for evaluating direct, indirect, and total effects in multilevel models when all relevant variables are measured at Level 1 and all effects are random. Formulas are provided for the mean and variance of the indirect and total effects and for the sampling variances of the average indirect and total effects.…

Integrating network ecology with applied conservation: a synthesis and guide to implementation.

PubMed

Kaiser-Bunbury, Christopher N; Blüthgen, Nico

2015-07-10

Ecological networks are a useful tool to study the complexity of biotic interactions at a community level. Advances in the understanding of network patterns encourage the application of a network approach in other disciplines than theoretical ecology, such as biodiversity conservation. So far, however, practical applications have been meagre. Here we present a framework for network analysis to be harnessed to advance conservation management by using plant-pollinator networks and islands as model systems. Conservation practitioners require indicators to monitor and assess management effectiveness and validate overall conservation goals. By distinguishing between two network attributes, the 'diversity' and 'distribution' of interactions, on three hierarchical levels (species, guild/group and network) we identify seven quantitative metrics to describe changes in network patterns that have implications for conservation. Diversity metrics are partner diversity, vulnerability/generality, interaction diversity and interaction evenness, and distribution metrics are the specialization indices d' and [Formula: see text] and modularity. Distribution metrics account for sampling bias and may therefore be suitable indicators to detect human-induced changes to plant-pollinator communities, thus indirectly assessing the structural and functional robustness and integrity of ecosystems. We propose an implementation pathway that outlines the stages that are required to successfully embed a network approach in biodiversity conservation. Most importantly, only if conservation action and study design are aligned by practitioners and ecologists through joint experiments, are the findings of a conservation network approach equally beneficial for advancing adaptive management and ecological network theory. We list potential obstacles to the framework, highlight the shortfall in empirical, mostly experimental, network data and discuss possible solutions. Published by Oxford University Press on behalf of the Annals of Botany Company.

Positive Network Assortativity of Influenza Vaccination at a High School: Implications for Outbreak Risk and Herd Immunity

PubMed Central

He, Jianping; Cao, Guohong; Rainey, Jeanette J.; Gao, Hongjiang; Uzicanin, Amra; Salathé, Marcel

2014-01-01

Schools are known to play a significant role in the spread of influenza. High vaccination coverage can reduce infectious disease spread within schools and the wider community through vaccine-induced immunity in vaccinated individuals and through the indirect effects afforded by herd immunity. In general, herd immunity is greatest when vaccination coverage is highest, but clusters of unvaccinated individuals can reduce herd immunity. Here, we empirically assess the extent of such clustering by measuring whether vaccinated individuals are randomly distributed or demonstrate positive assortativity across a United States high school contact network. Using computational models based on these empirical measurements, we further assess the impact of assortativity on influenza disease dynamics. We found that the contact network was positively assortative with respect to influenza vaccination: unvaccinated individuals tended to be in contact more often with other unvaccinated individuals than with vaccinated individuals, and these effects were most pronounced when we analyzed contact data collected over multiple days. Of note, unvaccinated males contributed substantially more than unvaccinated females towards the measured positive vaccination assortativity. Influenza simulation models using a positively assortative network resulted in larger average outbreak size, and outbreaks were more likely, compared to an otherwise identical network where vaccinated individuals were not clustered. These findings highlight the importance of understanding and addressing heterogeneities in seasonal influenza vaccine uptake for prevention of large, protracted school-based outbreaks of influenza, in addition to continued efforts to increase overall vaccine coverage. PMID:24505274

Evolution in response to direct and indirect ecological effects in pitcher plant inquiline communities.

PubMed

terHorst, Casey P

2010-12-01

Ecologists have long recognized the importance of indirect ecological effects on species abundances, coexistence, and diversity. However, the evolutionary consequences of indirect interactions are rarely considered. Here I conduct selection experiments and examine the evolutionary response of Colpoda sp., a ciliated protozoan, to other members of the inquiline community of purple pitcher plants (Sarracenia purpurea). I measured the evolution of six traits in response to (1) predation by mosquito larvae, (2) competition from other ciliated protozoans, and (3) simultaneous predation and competition. The latter treatment incorporated both direct effects and indirect effects due to interactions between predators and competitors. Population growth rate and cell size evolved in response to direct effects of predators and competitors. However, trait values in the multispecies treatment were similar to those in the monoculture treatment, indicating that direct effects were offset by strong indirect effects on the evolution of traits. For most of the traits measured, indirect effects were opposed to, and often stronger than, direct effects. These indirect effects occurred as a result of behavioral changes of the predator in the presence of competitors and as a result of reduced densities of competitors in the presence of predators. Incorporating indirect effects provides a more realistic description of how species evolve in complex natural communities.

Disrupted white matter structure underlies cognitive deficit in hypertensive patients.

PubMed

Li, Xin; Ma, Chao; Sun, Xuan; Zhang, Junying; Chen, Yaojing; Chen, Kewei; Zhang, Zhanjun

2016-09-01

Hypertension is considered a risk factor of cognitive impairments and could result in white matter changes. Current studies on hypertension-related white matter (WM) changes focus only on regional changes, and the information about global changes in WM structure network is limited. We assessed the cognitive function in 39 hypertensive patients and 37 healthy controls with a battery of neuropsychological tests. The WM structural networks were constructed by utilizing diffusion tensor tractography and calculated topological properties of the networks using a graph theoretical method. The direct and indirect correlations among cognitive impairments, brain WM network disruptions and hypertension were analyzed with structural equation modelling (SEM). Hypertensive patients showed deficits in executive function, memory and attention compared with controls. An aberrant connectivity of WM networks was found in the hypertensive patients (P Eglob = 0.005, P Lp = 0.005), especially in the frontal and parietal regions. Importantly, SEM analysis showed that the decline of executive function resulted from aberrant WM networks in hypertensive patients (p = 0.3788, CFI = 0.99). These results suggest that the cognitive decline in hypertensive patients was due to frontal and parietal WM disconnections. Our findings highlight the importance of brain protection in hypertension patients. • Hypertension has a negative effect on the performance of the cognitive domains • Reduced efficiencies of white matter networks were shown in hypertension • Disrupted white matter networks are responsible for poor cognitive function in hypertension.

Small molecule schweinfurthins selectively inhibit cancer cell proliferation and mTOR/AKT signaling by interfering with trans-Golgi-network trafficking

PubMed Central

Bao, Xingfeng; Zheng, Wanjun; Sugi, Naoko Hata; Agarwala, Kishan L; Xu, Qunli; Wang, Zichun; Tendyke, Karen; Lee, Winnie; Parent, Lana; Li, Wei; Cheng, Hongsheng; Shen, Yongchun; Taylor, Noel; Dezso, Zoltan; Du, Hong; Kotake, Yoshihiko; Zhao, Nanding; Wang, John; Postema, Maarten; Woodall-Jappe, Mary; Takase, Yasutaka; Uenaka, Toshimitsu; Kingston, David G I; Nomoto, Kenichi

2015-01-01

Natural compound schweinfurthins are of considerable interest for novel therapy development because of their selective anti-proliferative activity against human cancer cells. We previously reported the isolation of highly active schweinfurthins E-H, and in the present study, mechanisms of the potent and selective anti-proliferation were investigated. We found that schweinfurthins preferentially inhibited the proliferation of PTEN deficient cancer cells by indirect inhibition of AKT phosphorylation. Mechanistically, schweinfurthins and their analogs arrested trans-Golgi-network trafficking, an intracellular vesicular trafficking system, resulting in the induction of endoplasmic reticulum stress and the suppression of both lipid raft-mediated PI3K activation and mTOR/RheB complex formation, which collectively led to an effective inhibition of mTOR/AKT signaling. The trans-Golgi-network traffic arresting effect of schweinfurthins was associated with their in vitro binding activity to oxysterol-binding proteins that are known to regulate intracellular vesicular trafficking. Moreover, schweinfurthins were found to be highly toxic toward PTEN-deficient B cell lymphoma cells, and displayed 2 orders of magnitude lower activity toward normal human peripheral blood mononuclear cells and primary fibroblasts in vitro. These results revealed a previously unrecognized role of schweinfurthins in regulating trans-Golgi-network trafficking, and linked mechanistically this cellular effect with mTOR/AKT signaling and with cancer cell survival and growth. Our findings suggest the schweinfurthin class of compounds as a novel approach to modulate oncogenic mTOR/AKT signaling for cancer treatment. PMID:25729885

An Embedded Wireless Sensor Network with Wireless Power Transmission Capability for the Structural Health Monitoring of Reinforced Concrete Structures

PubMed Central

Gallucci, Luca; Menna, Costantino; Angrisani, Leopoldo; Asprone, Domenico

2017-01-01

Maintenance strategies based on structural health monitoring can provide effective support in the optimization of scheduled repair of existing structures, thus enabling their lifetime to be extended. With specific regard to reinforced concrete (RC) structures, the state of the art seems to still be lacking an efficient and cost-effective technique capable of monitoring material properties continuously over the lifetime of a structure. Current solutions can typically only measure the required mechanical variables in an indirect, but economic, manner, or directly, but expensively. Moreover, most of the proposed solutions can only be implemented by means of manual activation, making the monitoring very inefficient and then poorly supported. This paper proposes a structural health monitoring system based on a wireless sensor network (WSN) that enables the automatic monitoring of a complete structure. The network includes wireless distributed sensors embedded in the structure itself, and follows the monitoring-based maintenance (MBM) approach, with its ABCDE paradigm, namely: accuracy, benefit, compactness, durability, and easiness of operations. The system is structured in a node level and has a network architecture that enables all the node data to converge in a central unit. Human control is completely unnecessary until the periodic evaluation of the collected data. Several tests are conducted in order to characterize the system from a metrological point of view and assess its performance and effectiveness in real RC conditions. PMID:29112128

Operationalizing Network Theory for Ecosystem Service Assessments.

PubMed

Dee, Laura E; Allesina, Stefano; Bonn, Aletta; Eklöf, Anna; Gaines, Steven D; Hines, Jes; Jacob, Ute; McDonald-Madden, Eve; Possingham, Hugh; Schröter, Matthias; Thompson, Ross M

2017-02-01

Managing ecosystems to provide ecosystem services in the face of global change is a pressing challenge for policy and science. Predicting how alternative management actions and changing future conditions will alter services is complicated by interactions among components in ecological and socioeconomic systems. Failure to understand those interactions can lead to detrimental outcomes from management decisions. Network theory that integrates ecological and socioeconomic systems may provide a path to meeting this challenge. While network theory offers promising approaches to examine ecosystem services, few studies have identified how to operationalize networks for managing and assessing diverse ecosystem services. We propose a framework for how to use networks to assess how drivers and management actions will directly and indirectly alter ecosystem services. Copyright © 2016 Elsevier Ltd. All rights reserved.

Confidence Limits for the Indirect Effect: Distribution of the Product and Resampling Methods

ERIC Educational Resources Information Center

MacKinnon, David P.; Lockwood, Chondra M.; Williams, Jason

2004-01-01

The most commonly used method to test an indirect effect is to divide the estimate of the indirect effect by its standard error and compare the resulting z statistic with a critical value from the standard normal distribution. Confidence limits for the indirect effect are also typically based on critical values from the standard normal…

Maritime Aerosol Network (MAN) as a Component of AERONET

NASA Technical Reports Server (NTRS)

Smirnov, A.; Holben, B. N.; Slutsker, I.; Giles, D. M.; McClain, C. R.; Eck, T. F.; Sakerin, S. M.; Macke, A.; Croot, P.; Zibordi, G.;

Better sales networks.

PubMed

Ustüner, Tuba; Godes, David

2006-01-01

Anyone in sales will tell you that social networks are critical. The more contacts you have, the more leads you'll generate, and, ultimately, the more sales you'll make. But that's a vast oversimplification. Different configurations of networks produce different results, and the salesperson who develops a nuanced understanding of social networks will outshine competitors. The salesperson's job changes over the course of the selling process. Different abilities are required in each stage of the sale: identifying prospects, gaining buy-in from potential customers, creating solutions, and closing the deal. Success in the first stage, for instance, depends on the salesperson acquiring precise and timely information about opportunities from contacts in the marketplace. Closing the deal requires the salesperson to mobilize contacts from prior sales to act as references. Managers often view sales networks only in terms of direct contacts. But someone who knows lots of people doesn't necessarily have an effective network because networks often pay off most handsomely through indirect contacts. Moreover, the density of the connections in a network is important. Do a salesperson's contacts know all the same people, or are their associates widely dispersed? Sparse networks are better, for example, at generating unique information. Managers can use three levers--sales force structure, compensation, and skills development--to encourage salespeople to adopt a network-based view and make the best possible use of social webs. For example, the sales force can be restructured to decouple lead generation from other tasks because some people are very good at building diverse ties but not so good at maintaining other kinds of networks. Companies that take steps of this kind to help their sales teams build better networks will reap tremendous advantages.

Speaker gaze increases information coupling between infant and adult brains.

PubMed

Leong, Victoria; Byrne, Elizabeth; Clackson, Kaili; Georgieva, Stanimira; Lam, Sarah; Wass, Sam

2017-12-12

When infants and adults communicate, they exchange social signals of availability and communicative intention such as eye gaze. Previous research indicates that when communication is successful, close temporal dependencies arise between adult speakers' and listeners' neural activity. However, it is not known whether similar neural contingencies exist within adult-infant dyads. Here, we used dual-electroencephalography to assess whether direct gaze increases neural coupling between adults and infants during screen-based and live interactions. In experiment 1 ( n = 17), infants viewed videos of an adult who was singing nursery rhymes with ( i ) direct gaze (looking forward), ( ii ) indirect gaze (head and eyes averted by 20°), or ( iii ) direct-oblique gaze (head averted but eyes orientated forward). In experiment 2 ( n = 19), infants viewed the same adult in a live context, singing with direct or indirect gaze. Gaze-related changes in adult-infant neural network connectivity were measured using partial directed coherence. Across both experiments, the adult had a significant (Granger) causal influence on infants' neural activity, which was stronger during direct and direct-oblique gaze relative to indirect gaze. During live interactions, infants also influenced the adult more during direct than indirect gaze. Further, infants vocalized more frequently during live direct gaze, and individual infants who vocalized longer also elicited stronger synchronization from the adult. These results demonstrate that direct gaze strengthens bidirectional adult-infant neural connectivity during communication. Thus, ostensive social signals could act to bring brains into mutual temporal alignment, creating a joint-networked state that is structured to facilitate information transfer during early communication and learning. Copyright © 2017 the Author(s). Published by PNAS.

Speaker gaze increases information coupling between infant and adult brains

PubMed Central

Leong, Victoria; Byrne, Elizabeth; Clackson, Kaili; Georgieva, Stanimira; Lam, Sarah

2017-01-01

When infants and adults communicate, they exchange social signals of availability and communicative intention such as eye gaze. Previous research indicates that when communication is successful, close temporal dependencies arise between adult speakers’ and listeners’ neural activity. However, it is not known whether similar neural contingencies exist within adult–infant dyads. Here, we used dual-electroencephalography to assess whether direct gaze increases neural coupling between adults and infants during screen-based and live interactions. In experiment 1 (n = 17), infants viewed videos of an adult who was singing nursery rhymes with (i) direct gaze (looking forward), (ii) indirect gaze (head and eyes averted by 20°), or (iii) direct-oblique gaze (head averted but eyes orientated forward). In experiment 2 (n = 19), infants viewed the same adult in a live context, singing with direct or indirect gaze. Gaze-related changes in adult–infant neural network connectivity were measured using partial directed coherence. Across both experiments, the adult had a significant (Granger) causal influence on infants’ neural activity, which was stronger during direct and direct-oblique gaze relative to indirect gaze. During live interactions, infants also influenced the adult more during direct than indirect gaze. Further, infants vocalized more frequently during live direct gaze, and individual infants who vocalized longer also elicited stronger synchronization from the adult. These results demonstrate that direct gaze strengthens bidirectional adult–infant neural connectivity during communication. Thus, ostensive social signals could act to bring brains into mutual temporal alignment, creating a joint-networked state that is structured to facilitate information transfer during early communication and learning. PMID:29183980

Biocompatibility of polymer-infiltrated-ceramic-network (PICN) materials with Human Gingival Keratinocytes (HGKs).

PubMed

Grenade, Charlotte; De Pauw-Gillet, Marie-Claire; Pirard, Catherine; Bertrand, Virginie; Charlier, Corinne; Vanheusden, Alain; Mainjot, Amélie

2017-03-01

Biocompatibility of polymer-infiltrated-ceramic-network (PICN) materials, a new class of CAD-CAM composites, is poorly explored in the literature, in particular, no data are available regarding Human Gingival Keratinocytes (HGK). The first objective of this study was to evaluate the in vitro biocompatibility of PICNs with HGKs in comparison with other materials typically used for implant prostheses. The second objective was to correlate results with PICN monomer release and indirect cytotoxicity. HGK attachment, proliferation and spreading on PICN, grade V titanium (Ti), yttrium zirconia (Zi), lithium disilicate glass-ceramic (eM) and polytetrafluoroethylene (negative control) discs were evaluated using a specific insert-based culture system. For PICN and eM samples, monomer release in the culture medium was quantified by high performance liquid chromatography and indirect cytotoxicity tests were performed. Ti and Zi exhibited the best results regarding HGK viability, number and coverage. eM showed inferior results while PICN showed statistically similar results to eM but also to Ti regarding cell number and to Ti and Zi regarding cell viability. No monomer release from PICN discs was found, nor indirect cytotoxicity, as for eM. The results confirmed the excellent behavior of Ti and Zi with gingival cells. Even if polymer based, PICN materials exhibited intermediate results between Ti-Zi and eM. These promising results could notably be explained by PICN high temperature-high pressure (HT-HP) innovative polymerization mode, as confirmed by the absence of monomer release and indirect cytotoxicity. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Development of flood probability charts for urban drainage network in coastal areas through a simplified joint assessment approach

NASA Astrophysics Data System (ADS)

Archetti, R.; Bolognesi, A.; Casadio, A.; Maglionico, M.

2011-04-01

The operating conditions of urban drainage networks during storm events certainly depend on the hydraulic conveying capacity of conduits but also on downstream boundary conditions. This is particularly true in costal areas where the level of the receiving water body is directly or indirectly affected by tidal or wave effects. In such cases, not just different rainfall conditions (varying intensity and duration), but also different sea-levels and their effects on the network operation should be considered. This paper aims to study the behaviour of a seaside town storm sewer network, estimating the threshold condition for flooding and proposing a simplified method to assess the urban flooding severity as a function of either climate variables. The case study is a portion of the drainage system of Rimini (Italy), implemented and numerically modelled by means of InfoWorks CS code. The hydraulic simulation of the sewerage system has therefore allowed to identify the percentage of nodes of the drainage system where flooding is expected to occur. Combining these percentages with both climate variables values has lead to the definition charts representing the combined degree of risk "sea-rainfall" for the drainage system under investigation. A final comparison between such charts and the results obtained from a one-year sea-rainfall time series has confirmed the reliability of the analysis.

Development of flood probability charts for urban drainage network in coastal areas through a simplified joint assessment approach

NASA Astrophysics Data System (ADS)

Archetti, R.; Bolognesi, A.; Casadio, A.; Maglionico, M.

2011-10-01

The operating conditions of urban drainage networks during storm events depend on the hydraulic conveying capacity of conduits and also on downstream boundary conditions. This is particularly true in coastal areas where the level of the receiving water body is directly or indirectly affected by tidal or wave effects. In such cases, not just different rainfall conditions (varying intensity and duration), but also different sea-levels and their effects on the network operation should be considered. This paper aims to study the behaviour of a seaside town storm sewer network, estimating the threshold condition for flooding and proposing a simplified method to assess the urban flooding severity as a function of climate variables. The case study is a portion of the drainage system of Rimini (Italy), implemented and numerically modelled by means of InfoWorks CS code. The hydraulic simulation of the sewerage system identified the percentage of nodes of the drainage system where flooding is expected to occur. Combining these percentages with both climate variables' values has lead to the definition of charts representing the combined degree of risk "rainfall-sea level" for the drainage system under investigation. A final comparison between such charts and the results obtained from a one-year rainfall-sea level time series has demonstrated the reliability of the analysis.

Functional annotation of regulatory pathways.

PubMed

Pandey, Jayesh; Koyutürk, Mehmet; Kim, Yohan; Szpankowski, Wojciech; Subramaniam, Shankar; Grama, Ananth

2007-07-01

Standardized annotations of biomolecules in interaction networks (e.g. Gene Ontology) provide comprehensive understanding of the function of individual molecules. Extending such annotations to pathways is a critical component of functional characterization of cellular signaling at the systems level. We propose a framework for projecting gene regulatory networks onto the space of functional attributes using multigraph models, with the objective of deriving statistically significant pathway annotations. We first demonstrate that annotations of pairwise interactions do not generalize to indirect relationships between processes. Motivated by this result, we formalize the problem of identifying statistically overrepresented pathways of functional attributes. We establish the hardness of this problem by demonstrating the non-monotonicity of common statistical significance measures. We propose a statistical model that emphasizes the modularity of a pathway, evaluating its significance based on the coupling of its building blocks. We complement the statistical model by an efficient algorithm and software, Narada, for computing significant pathways in large regulatory networks. Comprehensive results from our methods applied to the Escherichia coli transcription network demonstrate that our approach is effective in identifying known, as well as novel biological pathway annotations. Narada is implemented in Java and is available at http://www.cs.purdue.edu/homes/jpandey/narada/.

Can mental health interventions change social networks? A systematic review.

PubMed

Anderson, Kimberley; Laxhman, Neelam; Priebe, Stefan

2015-11-21

Social networks of patients with psychosis can provide social support, and improve health and social outcomes, including quality of life. However, patients with psychosis often live rather isolated with very limited social networks. Evidence for interventions targeting symptoms or social skills, are largely unsuccessful at improving social networks indirectly. As an alternative, interventions may directly focus on expanding networks. In this systematic review, we assessed what interventions have previously been tested for this and to what extent they have been effective. A systematic review was conducted of randomised controlled trials, testing psychosocial interventions designed to directly increase the social networks of patients with psychosis. Searches of five online databases (PsycINFO, CINAHL, Cochrane Database, MEDLINE, Embase), hand searching of grey literature, and both forward and backward snowballing of key papers were conducted and completed on 12 December 2014. Trial reports were included if they were written in English, the social network size was the primary outcome, participants were ≥ 18 years old and diagnosed with a psychotic disorder. Five studies (n = 631 patients) met the complete inclusion criteria. Studies were from different countries and published since 2008. Four trials had significant positive results, i.e. an observable increase in patients' social network size at the end of the intervention. The interventions included: guided peer support, a volunteer partner scheme, supported engagement in social activity, dog-assisted integrative psychological therapy and psychosocial skills training. Other important elements featured were the presence of a professional, and a focus on friendships and peers outside of services and the immediate family. Despite the small number and heterogeneity of included studies, the results suggest that interventions directly targeting social isolation can be effective and achieve a meaningful increase in patients' networks. Thus, although limited, the existing evidence is encouraging, and the range of interventions used in the reported trials leave various options for future research and further improvements. Future research is needed to test the findings in different settings, identify which components are particularly effective, and determine to what extent the increased networks, over time, impact on patients' symptoms and quality of life.

Indirect effects in community ecology: Their definition, study and importance.

PubMed

Strauss, S Y

1991-07-01

The diversity of indirect interactions that can occur within communities is large. Recent research on indirect interactions is scattered in the literature under numerous labels. The definition of indirect effects is an important aspect of their study, and clarifies some of the subtle differences among indirect effects found in natural communities. Choosing which species to study, how to manipulate species and for what duration, which attributes to measure and, finally, which analytical techniques to use are all problems facing the community ecologist. Ultimately, we are striving for the best means of determining the relative importance of direct and indirect effects in structuring communities. Copyright © 1991. Published by Elsevier Ltd.

Cylinder pressure reconstruction based on complex radial basis function networks from vibration and speed signals

NASA Astrophysics Data System (ADS)

Johnsson, Roger

2006-11-01

Methods to measure and monitor the cylinder pressure in internal combustion engines can contribute to reduced fuel consumption, noise and exhaust emissions. As direct measurements of the cylinder pressure are expensive and not suitable for measurements in vehicles on the road indirect methods which measure cylinder pressure have great potential value. In this paper, a non-linear model based on complex radial basis function (RBF) networks is proposed for the reconstruction of in-cylinder pressure pulse waveforms. Input to the network is the Fourier transforms of both engine structure vibration and crankshaft speed fluctuation. The primary reason for the use of Fourier transforms is that different frequency regions of the signals are used for the reconstruction process. This approach also makes it easier to reduce the amount of information that is used as input to the RBF network. The complex RBF network was applied to measurements from a 6-cylinder ethanol powered diesel engine over a wide range of running conditions. Prediction accuracy was validated by comparing a number of parameters between the measured and predicted cylinder pressure waveform such as maximum pressure, maximum rate of pressure rise and indicated mean effective pressure. The performance of the network was also evaluated for a number of untrained running conditions that differ both in speed and load from the trained ones. The results for the validation set were comparable to the trained conditions.

A Three-way Decomposition of a Total Effect into Direct, Indirect, and Interactive Effects

PubMed Central

VanderWeele, Tyler J.

2013-01-01

Recent theory in causal inference has provided concepts for mediation analysis and effect decomposition that allow one to decompose a total effect into a direct and an indirect effect. Here, it is shown that what is often taken as an indirect effect can in fact be further decomposed into a “pure” indirect effect and a mediated interactive effect, thus yielding a three-way decomposition of a total effect (direct, indirect, and interactive). This three-way decomposition applies to difference scales and also to additive ratio scales and additive hazard scales. Assumptions needed for the identification of each of these three effects are discussed and simple formulae are given for each when regression models allowing for interaction are used. The three-way decomposition is illustrated by examples from genetic and perinatal epidemiology, and discussion is given to what is gained over the traditional two-way decomposition into simply a direct and an indirect effect. PMID:23354283

Interarrival times of message propagation on directed networks.

PubMed

Mihaljev, Tamara; de Arcangelis, Lucilla; Herrmann, Hans J

2011-08-01

One of the challenges in fighting cybercrime is to understand the dynamics of message propagation on botnets, networks of infected computers used to send viruses, unsolicited commercial emails (SPAM) or denial of service attacks. We map this problem to the propagation of multiple random walkers on directed networks and we evaluate the interarrival time distribution between successive walkers arriving at a target. We show that the temporal organization of this process, which models information propagation on unstructured peer to peer networks, has the same features as SPAM reaching a single user. We study the behavior of the message interarrival time distribution on three different network topologies using two different rules for sending messages. In all networks the propagation is not a pure Poisson process. It shows universal features on Poissonian networks and a more complex behavior on scale free networks. Results open the possibility to indirectly learn about the process of sending messages on networks with unknown topologies, by studying interarrival times at any node of the network.

Interarrival times of message propagation on directed networks

NASA Astrophysics Data System (ADS)

Mihaljev, Tamara; de Arcangelis, Lucilla; Herrmann, Hans J.

2011-08-01

One of the challenges in fighting cybercrime is to understand the dynamics of message propagation on botnets, networks of infected computers used to send viruses, unsolicited commercial emails (SPAM) or denial of service attacks. We map this problem to the propagation of multiple random walkers on directed networks and we evaluate the interarrival time distribution between successive walkers arriving at a target. We show that the temporal organization of this process, which models information propagation on unstructured peer to peer networks, has the same features as SPAM reaching a single user. We study the behavior of the message interarrival time distribution on three different network topologies using two different rules for sending messages. In all networks the propagation is not a pure Poisson process. It shows universal features on Poissonian networks and a more complex behavior on scale free networks. Results open the possibility to indirectly learn about the process of sending messages on networks with unknown topologies, by studying interarrival times at any node of the network.

DSGRN: Examining the Dynamics of Families of Logical Models.

PubMed

Cummins, Bree; Gedeon, Tomas; Harker, Shaun; Mischaikow, Konstantin

2018-01-01

We present a computational tool DSGRN for exploring the dynamics of a network by computing summaries of the dynamics of switching models compatible with the network across all parameters. The network can arise directly from a biological problem, or indirectly as the interaction graph of a Boolean model. This tool computes a finite decomposition of parameter space such that for each region, the state transition graph that describes the coarse dynamical behavior of a network is the same. Each of these parameter regions corresponds to a different logical description of the network dynamics. The comparison of dynamics across parameters with experimental data allows the rejection of parameter regimes or entire networks as viable models for representing the underlying regulatory mechanisms. This in turn allows a search through the space of perturbations of a given network for networks that robustly fit the data. These are the first steps toward discovering a network that optimally matches the observed dynamics by searching through the space of networks.

Molecular modeling of fibronectin adsorption on topographically nanostructured rutile (110) surfaces

NASA Astrophysics Data System (ADS)

Guo, Chuangqiang; Wu, Chunya; Chen, Mingjun; Zheng, Ting; Chen, Ni; Cummings, Peter T.

2016-10-01

To investigate the topographical dependency of protein adsorption, molecular dynamics simulations were employed to describe the adsorption behavior of the tenth type-III module of fibronectin (FN-III10) on nanostructured rutile (110) surfaces. The results indicated that the residence time of adsorbed FN-III10 largely relied on its binding mode (direct or indirect) with the substrate and the region for protein migration on the periphery (protrusion) or in the interior (cavity or groove) of nanostructures. In the direct binding mode, FN-III10 molecules were found to be 'trapped' at the anchoring sites of rutile surface, or even penetrate deep into the interior of nanostructures, regardless of the presented geometrical features. In the indirect binding mode, FN-III10 molecules were indirectly connected to the substrate via a hydrogen-bond network (linking FN-III10 and interfacial hydrations). The facets created by nanostructures, which exerted restraints on protein migration, were suggested to play an important role in the stability of indirect FN-III10-rutile binding. However, a doubly unfavorable situation - indirect FN-III10-rutile connections bridged by a handful of mediating waters and few constraints on movement of protein provided by nanostructures - would result in an early desorption of protein.

Effect of social networks and well-being on acute care needs.

PubMed

Sintonen, Sanna; Pehkonen, Aini

2014-01-01

The effect of social surroundings has been noted as an important component of the well-being of elderly people. A strong social network and strong and steady relationships are necessary for coping when illness or functional limitations occur in later life. Vulnerability can affect well-being and functioning particularly when sudden life changes occur. The objective of this study was to analyse how the determinants of social well-being affect individual acute care needs when sudden life changes occur. Empirical evidence was collected using a cross-sectional mail survey in Finland in January 2011 among individuals aged 55-79 years. The age-stratified random sample covered 3000 individuals, and the eventual response rate was 56% (1680). Complete responses were received from 1282 respondents (42.7%). The study focuses on the compactness of social networks, social disability, the stability of social relationships and the fear of loneliness as well as how these factors influence acute care needs. The measurement was based on a latent factor structure, and the key concepts were measured using two ordinal items. The results of the structural model suggest that the need for care is directly affected by social disability and the fear of loneliness. In addition, social disability is a determinant of the fear of loneliness and therefore plays an important role if sudden life changes occur. The compactness of social networks decreases social disability and partly diminishes the fear of loneliness and therefore has an indirect effect on the need for care. The stability of social relationships was influenced by the social networks and disability, but was an insignificant predictor of care needs. To conclude, social networks and well-being can decrease care needs, and supportive actions should be targeted to avoid loneliness and social isolation so that the informal network could be applied as an aspect of care-giving when acute life changes occur. © 2013 John Wiley & Sons Ltd.

Effects of risk factors for and components of metabolic syndrome on the quality of life of patients with systemic lupus erythematosus: a structural equation modeling approach.

PubMed

Lee, Jeong-Won; Kang, Ji-Hyoun; Lee, Kyung-Eun; Park, Dong-Jin; Kang, Seong Wook; Kwok, Seung-Ki; Kim, Seong-Kyu; Choe, Jung-Yoon; Kim, Hyoun-Ah; Sung, Yoon-Kyoung; Shin, Kichul; Lee, Sang-Il; Lee, Chang Hoon; Choi, Sung Jae; Lee, Shin-Seok

2018-01-01

This study assessed the relationships among the risk factors for and components of metabolic syndrome (MetS) and health-related quality of life (HRQOL) in a hypothesized causal model using structural equation modeling (SEM) in patients with systemic lupus erythematosus (SLE). Of the 505 SLE patients enrolled in the Korean Lupus Network (KORNET registry), 244 had sufficient data to assess the components of MetS at enrollment. Education level, monthly income, corticosteroid dose, Systemic Lupus Erythematosus Disease Activity Index, Physicians' Global Assessment, Beck Depression Inventory, MetS components, and the Short Form-36 at the time of cohort entry were determined. SEM was used to test the causal relationship based on the Analysis of Moment Structure. The average age of the 244 patients was 40.7 ± 11.8 years. The SEM results supported the good fit of the model (χ 2  = 71.629, p = 0.078, RMSEA 0.034, CFI 0.972). The final model showed a direct negative effect of higher socioeconomic status and a positive indirect effect of higher disease activity on MetS, the latter through corticosteroid dose. MetS did not directly impact HRQOL but had an indirect negative impact on it, through depression. In our causal model, MetS risk factors were related to MetS components. The latter had a negative indirect impact on HRQOL, through depression. Clinicians should consider socioeconomic status and medication and seek to modify disease activity, MetS, and depression to improve the HRQOL of SLE patients.

Early neuroimaging markers of FOXP2 intragenic deletion.

PubMed

Liégeois, Frédérique J; Hildebrand, Michael S; Bonthrone, Alexandra; Turner, Samantha J; Scheffer, Ingrid E; Bahlo, Melanie; Connelly, Alan; Morgan, Angela T

2016-10-13

FOXP2 is the major gene associated with severe, persistent, developmental speech and language disorders. While studies in the original family in which a FOXP2 mutation was found showed volume reduction and reduced activation in core language and speech networks, there have been no imaging studies of different FOXP2 mutations. We conducted a multimodal MRI study in an eight-year-old boy (A-II) with a de novo FOXP2 intragenic deletion. A-II showed marked bilateral volume reductions in the hippocampus, thalamus, globus pallidus, and caudate nucleus compared with 26 control males (effect sizes from -1 to -3). He showed no detectable functional MRI activity when repeating nonsense words. The hippocampus is implicated for the first time in FOXP2 diseases. We conclude that FOXP2 anomaly is either directly or indirectly associated with atypical development of widespread subcortical networks early in life.

De retibus socialibus et legibus momenti

NASA Astrophysics Data System (ADS)

Gayo-Avello, D.; Brenes, D. J.; Fernández-Fernández, D.; Fernández-Menéndez, M. E.; García-Suárez, R.

2011-05-01

Online Social Networks (OSNs) are a cutting edge topic. Almost everybody —users, marketers, brands, companies, and researchers— is approaching OSNs to better understand them and take advantage of their benefits. Maybe one of the key concepts underlying OSNs is that of influence which is highly related, although not entirely identical, to those of popularity and centrality. Influence is, according to Merriam-Webster, "the capacity of causing an effect in indirect or intangible ways". Hence, in the context of OSNs, it has been proposed to analyze the clicks received by promoted URLs in order to check for any positive correlation between the number of visits and different "influence" scores. That evaluation methodology is used in this letter to compare a number of those techniques with a new method firstly described here. That new method is a simple and rather elegant solution which tackles with influence in OSNs by applying a physical metaphor. On social networks and the laws of influence.

The Role of Sex of Peers and Gender-Typed Activities in Young Children’s Peer Affiliative Networks: A Longitudinal Analysis of Selection and Influence

PubMed Central

Martin, Carol Lynn; Kornienko, Olga; Schaefer, David R.; Hanish, Laura D.; Fabes, Richard A.; Goble, Priscilla

2012-01-01

A stochastic actor-based model was used to investigate the origins of sex segregation by examining how similarity in sex and time spent in gender-typed activities affected affiliation network selection and how peers influenced children’s (N = 292; M age = 4.3 years) activity involvement. Gender had powerful effects on interactions through direct and indirect pathways. Children selected playmates of the same-sex and with similar levels of gender-typed activities. Selection based on gender-typed activities partially mediated selection based on sex. Children influenced one another’s engagement in gender-typed activities. When mechanisms producing sex segregation were compared, the largest contributor was selection based on sex; less was due to activity-based selection and peer influence. Implications for sex segregation and gender development are discussed. PMID:23252713

Female College Students’ Media Use and Academic Outcomes: Results from a Longitudinal Cohort Study

PubMed Central

Walsh, Jennifer L.; Fielder, Robyn L.; Carey, Kate B.; Carey, Michael P.

2013-01-01

This longitudinal study describes women’s media use during their first year of college and examines associations between media use and academic outcomes. Female students (N = 483, Mage = 18.1 years) reported on their use of 11 media forms and their grade point average, academic behaviors, academic confidence, and problems affecting schoolwork. Allowing for multi-tasking, women reported nearly 12 hours of media use per day; use of texting, music, the Internet, and social networking was heaviest. In general, media use was negatively associated with academic outcomes after controlling for prior academics and demographics. Exceptions were newspaper reading and music listening, which were positively associated with academic outcomes. There were significant indirect effects of magazine reading and social networking on GPA via academic behaviors, confidence, and problems. Results show that female college students are heavy users of new media, and that some forms of media use may adversely impact academic performance. PMID:24505554

Pneumonia's second wind? A case study of the global health network for childhood pneumonia.

PubMed

Berlan, David

2016-04-01

Advocacy, policy, research and intervention efforts against childhood pneumonia have lagged behind other health issues, including malaria, measles and tuberculosis. Accelerating progress on the issue began in 2008, following decades of efforts by individuals and organizations to address the leading cause of childhood mortality and establish a global health network. This article traces the history of this network's formation and evolution to identify lessons for other global health issues. Through document review and interviews with current, former and potential network members, this case study identifies five distinct eras of activity against childhood pneumonia: a period of isolation (post WWII to 1984), the duration of WHO's Acute Respiratory Infections (ARI) Programme (1984-1995), Integrated Management of Childhood illness's (IMCI) early years (1995-2003), a brief period of network re-emergence (2003-2008) and recent accelerating progress (2008 on). Analysis of these eras reveals the critical importance of building a shared identity in order to form an effective network and take advantage of emerging opportunities. During the ARI era, an initial network formed around a relatively narrow shared identity focused on community-level care. The shift to IMCI led to the partial dissolution of this network, stalled progress on addressing pneumonia in communities and missed opportunities. Frustrated with lack of progress on the issue, actors began forming a network and shared identity that included a broad spectrum of those whose interests overlap with pneumonia. As the network coalesced and expanded, its members coordinated and collaborated on conducting and sharing research on severity and tractability, crafting comprehensive strategies and conducting advocacy. These network activities exerted indirect influence leading to increased attention, funding, policies and some implementation. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine © The Author 2015; all rights reserved.

Preschool children's behavioral tendency toward social indirect reciprocity.

PubMed

Kato-Shimizu, Mayuko; Onishi, Kenji; Kanazawa, Tadahiro; Hinobayashi, Toshihiko

2013-01-01

Social indirect reciprocity seems to be crucial in enabling large-scale cooperative networks among genetically unrelated individuals in humans. However, there are relatively few studies on social indirect reciprocity in children compared to adults. Investigating whether young children have a behavioral tendency toward social indirect reciprocity will help us understand how and when the fundamental ability to form cooperative relationships among adults is acquired. Using naturalistic observation at a nursery school, this study examined whether 5- to 6-year-olds show a behavioral tendency to engage in social indirect reciprocity in response to their peers' prosocial behavior toward a third party. The results revealed that bystander children tended to display prosocial behavior toward their peers more frequently after observing these peers' prosocial behavior toward third-party peers, compared with control situations; this suggests that 5- to 6-year-olds may have an essential behavioral tendency to establish social indirect reciprocity when interacting with peers in their daily lives. In addition, bystanders tended to display affiliative behavior after observing focal children's prosocial behavior. In other words, observing peers' prosocial behavior toward third-party peers evoked bystanders' positive emotions toward the helpers. Considering both the present results and previous findings, we speculate that in preschoolers, such positive emotions might mediate the increase in the bystander's prosocial behavior toward the helper. In addition, an intuitional emotional process plays an important role in the preschooler's behavioral tendency toward social indirect reciprocity in natural interactions with peers.

Preschool Children’s Behavioral Tendency toward Social Indirect Reciprocity

PubMed Central

Kanazawa, Tadahiro; Hinobayashi, Toshihiko

2013-01-01

Social indirect reciprocity seems to be crucial in enabling large-scale cooperative networks among genetically unrelated individuals in humans. However, there are relatively few studies on social indirect reciprocity in children compared to adults. Investigating whether young children have a behavioral tendency toward social indirect reciprocity will help us understand how and when the fundamental ability to form cooperative relationships among adults is acquired. Using naturalistic observation at a nursery school, this study examined whether 5- to 6-year-olds show a behavioral tendency to engage in social indirect reciprocity in response to their peers’ prosocial behavior toward a third party. The results revealed that bystander children tended to display prosocial behavior toward their peers more frequently after observing these peers’ prosocial behavior toward third-party peers, compared with control situations; this suggests that 5- to 6-year-olds may have an essential behavioral tendency to establish social indirect reciprocity when interacting with peers in their daily lives. In addition, bystanders tended to display affiliative behavior after observing focal children’s prosocial behavior. In other words, observing peers’ prosocial behavior toward third-party peers evoked bystanders’ positive emotions toward the helpers. Considering both the present results and previous findings, we speculate that in preschoolers, such positive emotions might mediate the increase in the bystander’s prosocial behavior toward the helper. In addition, an intuitional emotional process plays an important role in the preschooler’s behavioral tendency toward social indirect reciprocity in natural interactions with peers. PMID:23951040

Consumers mediate the effects of experimental ocean acidification and warming on primary producers.

PubMed

Alsterberg, Christian; Eklöf, Johan S; Gamfeldt, Lars; Havenhand, Jonathan N; Sundbäck, Kristina

2013-05-21

It is well known that ocean acidification can have profound impacts on marine organisms. However, we know little about the direct and indirect effects of ocean acidification and also how these effects interact with other features of environmental change such as warming and declining consumer pressure. In this study, we tested whether the presence of consumers (invertebrate mesograzers) influenced the interactive effects of ocean acidification and warming on benthic microalgae in a seagrass community mesocosm experiment. Net effects of acidification and warming on benthic microalgal biomass and production, as assessed by analysis of variance, were relatively weak regardless of grazer presence. However, partitioning these net effects into direct and indirect effects using structural equation modeling revealed several strong relationships. In the absence of grazers, benthic microalgae were negatively and indirectly affected by sediment-associated microalgal grazers and macroalgal shading, but directly and positively affected by acidification and warming. Combining indirect and direct effects yielded no or weak net effects. In the presence of grazers, almost all direct and indirect climate effects were nonsignificant. Our analyses highlight that (i) indirect effects of climate change may be at least as strong as direct effects, (ii) grazers are crucial in mediating these effects, and (iii) effects of ocean acidification may be apparent only through indirect effects and in combination with other variables (e.g., warming). These findings highlight the importance of experimental designs and statistical analyses that allow us to separate and quantify the direct and indirect effects of multiple climate variables on natural communities.

From allosteric drugs to allo-network drugs: state of the art and trends of design, synthesis and computational methods.

PubMed

Csermely, Peter; Nussinov, Ruth; Szilágyi, András

2013-01-01

Allosteric drugs bind to sites which are usually less conserved evolutionarily as compared to orthosteric sites. As such, they can discriminate between closely related proteins, have fewer side effects, and a consequent lower concentration can convey a lesser likelihood of receptor desensitization. However, an allosteric mode of action may also make the results of preclinical and animal experiments less predictive. The sensitivity of the allosteric consequences to the environment further increases the importance of accounting for patient population diversity. Even subtle differences in protein sequence, in cellular metabolic states or in target tissues, can result in different outcomes. This mini-hot-topic issue of CTMC showcases some successes and challenges of allosteric drug development through the examples of seventransmembrane (GPCR), AMPA, NMDA and metabotropic glutamate receptors, as well as the morpheein model of allosterism involved in inherent metabolic errors. Finally, the development of allo-network drugs, which are allosteric drugs acting indirectly on the neighborhood of the pharmacological target in protein-protein interaction or signaling networks, is described.

Origin of the Giant Honeycomb Network of Quinones on Cu(111)

NASA Astrophysics Data System (ADS)

Einstein, T. L.; Kim, Kwangmoo; Wyrick, Jon; Cheng, Zhihai; Bartels, Ludwig; Berland, Kristian; Hyldgaard, Per

2011-03-01

We discuss the factors that lead to the amazing regular giant honeycomb network formed by quinones on Cu(111). Using a related lattice gas model with many characteristic energies, we can reproduce many experimental features. These models require a long-range attraction, which can be attributed to indirect interactions mediated by the Shockley surface state of Cu(111). However, Wyrick's preceding talk gave evidence that the network self-selects for the size of the pore rather than for the periodicity of the superstructure, suggesting that confined states are the key ingredient. We discuss this phenomenon in terms of the magic numbers of 2D quantum dots. We also report calculations of the effects of anthraquinones (AQ) in modifying the surface states by considering a superlattice of AQ chains with various separations. We discuss implications of these results for tuning the electronic states and, thence, superstructures. Supported by (TLE) NSF CHE 07-50334 & UMD MRSEC DMR 05-20471, (JW & LB) NSF CHE NSF CHE 07-49949, (KB & PH) Swedish Vetenskapsrådet VR 621-2008-4346.

Flood impacts on a water distribution network

NASA Astrophysics Data System (ADS)

Arrighi, Chiara; Tarani, Fabio; Vicario, Enrico; Castelli, Fabio

2017-12-01

Floods cause damage to people, buildings and infrastructures. Water distribution systems are particularly exposed, since water treatment plants are often located next to the rivers. Failure of the system leads to both direct losses, for instance damage to equipment and pipework contamination, and indirect impact, since it may lead to service disruption and thus affect populations far from the event through the functional dependencies of the network. In this work, we present an analysis of direct and indirect damages on a drinking water supply system, considering the hazard of riverine flooding as well as the exposure and vulnerability of active system components. The method is based on interweaving, through a semi-automated GIS procedure, a flood model and an EPANET-based pipe network model with a pressure-driven demand approach, which is needed when modelling water distribution networks in highly off-design conditions. Impact measures are defined and estimated so as to quantify service outage and potential pipe contamination. The method is applied to the water supply system of the city of Florence, Italy, serving approximately 380 000 inhabitants. The evaluation of flood impact on the water distribution network is carried out for different events with assigned recurrence intervals. Vulnerable elements exposed to the flood are identified and analysed in order to estimate their residual functionality and to simulate failure scenarios. Results show that in the worst failure scenario (no residual functionality of the lifting station and a 500-year flood), 420 km of pipework would require disinfection with an estimated cost of EUR 21 million, which is about 0.5 % of the direct flood losses evaluated for buildings and contents. Moreover, if flood impacts on the water distribution network are considered, the population affected by the flood is up to 3 times the population directly flooded.

Cruel intentions on television and in real life: can viewing indirect aggression increase viewers' subsequent indirect aggression?

PubMed

Coyne, Sarah M; Archer, John; Eslea, Mike

2004-07-01

Numerous studies have shown that viewing violence in the media can influence an individual's subsequent aggression, but none have examined the effect of viewing indirect aggression. This study examines the immediate effect of viewing indirect and direct aggression on subsequent indirect aggression among 199 children ages 11 to 14 years. They were shown an indirect, direct, or no-aggression video and their subsequent indirect aggression was measured by negative evaluation of a confederate and responses to a vignette. Participants viewing indirect or direct aggression gave a more negative evaluation of and less money to a confederate than participants viewing no-aggression. Participants viewing indirect aggression gave less money to the confederate than those viewing direct aggression. Participants viewing indirect aggression gave more indirectly aggressive responses to an ambiguous situation and participants viewing direct aggression gave more directly aggressive responses. This study provides the first evidence that viewing indirect aggression in the media can have an immediate impact on subsequent aggression.

Energy effectiveness and the ecology of work: Links to productivity and well-being

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heerwagen, J.; Johnson, J.A.; Brothers, P.

In general, research on the positive outcomes of buildings lags behind research on problems and discomforts. A similar state exists in the field of medicine. The medical profession knows far more about what makes us sick than what makes us healthy. However, they also know that the mere absence of bad habits does not by itself promotes good health. Healthiness derives from a very different set of characteristics--including one's social network, psychological hardiness, general outlook on life, and a perceived sense of control over life situations. Research and theory in environmental psychology suggests that a similar situation exists in buildings.more » That is, the mere absence of discomforts and problems may not by itself produce high states of well being and performance. Realization of well-being and performance benefits may depend upon the degrees to which a building directly or indirectly affects psychological and cognitive functioning and physical health. An accumulating body of research in cognitive neuroscience, health psychology, and organizational behavior suggests that the physical environment can play a role in cultivating high states of well being and performance. While some of these features and attributes are directly related to energy efficient design, others have more indirect, and less obvious, linkages. In this paper, the authors look at research on factors affecting human performance, with an emphasis on information and knowledge based work. The paper includes a discussion about the effects of building design features on performance, well being, and comfort. They explore the energy linkages, both direct and indirect, in the final section of the paper.« less

Partitioning direct and indirect effects reveals the response of water-limited ecosystems to elevated CO2.

PubMed

Fatichi, Simone; Leuzinger, Sebastian; Paschalis, Athanasios; Langley, J Adam; Donnellan Barraclough, Alicia; Hovenden, Mark J

2016-10-24

Increasing concentrations of atmospheric carbon dioxide are expected to affect carbon assimilation and evapotranspiration (ET), ultimately driving changes in plant growth, hydrology, and the global carbon balance. Direct leaf biochemical effects have been widely investigated, whereas indirect effects, although documented, elude explicit quantification in experiments. Here, we used a mechanistic model to investigate the relative contributions of direct (through carbon assimilation) and indirect (via soil moisture savings due to stomatal closure, and changes in leaf area index) effects of elevated CO 2 across a variety of ecosystems. We specifically determined which ecosystems and climatic conditions maximize the indirect effects of elevated CO 2 The simulations suggest that the indirect effects of elevated CO 2 on net primary productivity are large and variable, ranging from less than 10% to more than 100% of the size of direct effects. For ET, indirect effects were, on average, 65% of the size of direct effects. Indirect effects tended to be considerably larger in water-limited ecosystems. As a consequence, the total CO 2 effect had a significant, inverse relationship with the wetness index and was directly related to vapor pressure deficit. These results have major implications for our understanding of the CO 2 response of ecosystems and for global projections of CO 2 fertilization, because, although direct effects are typically understood and easily reproducible in models, simulations of indirect effects are far more challenging and difficult to constrain. Our findings also provide an explanation for the discrepancies between experiments in the total CO 2 effect on net primary productivity.

Pneumonia’s second wind? A case study of the global health network for childhood pneumonia

PubMed Central

Berlan, David

2016-01-01

Advocacy, policy, research and intervention efforts against childhood pneumonia have lagged behind other health issues, including malaria, measles and tuberculosis. Accelerating progress on the issue began in 2008, following decades of efforts by individuals and organizations to address the leading cause of childhood mortality and establish a global health network. This article traces the history of this network’s formation and evolution to identify lessons for other global health issues. Through document review and interviews with current, former and potential network members, this case study identifies five distinct eras of activity against childhood pneumonia: a period of isolation (post WWII to 1984), the duration of WHO’s Acute Respiratory Infections (ARI) Programme (1984–1995), Integrated Management of Childhood illness’s (IMCI) early years (1995–2003), a brief period of network re-emergence (2003–2008) and recent accelerating progress (2008 on). Analysis of these eras reveals the critical importance of building a shared identity in order to form an effective network and take advantage of emerging opportunities. During the ARI era, an initial network formed around a relatively narrow shared identity focused on community-level care. The shift to IMCI led to the partial dissolution of this network, stalled progress on addressing pneumonia in communities and missed opportunities. Frustrated with lack of progress on the issue, actors began forming a network and shared identity that included a broad spectrum of those whose interests overlap with pneumonia. As the network coalesced and expanded, its members coordinated and collaborated on conducting and sharing research on severity and tractability, crafting comprehensive strategies and conducting advocacy. These network activities exerted indirect influence leading to increased attention, funding, policies and some implementation. PMID:26438780

Network meta-analysis of probiotics to prevent respiratory infections in children and adolescents.

PubMed

Amaral, Marina Azambuja; Guedes, Gabriela Helena Barbosa Ferreira; Epifanio, Matias; Wagner, Mario Bernardes; Jones, Marcus Herbert; Mattiello, Rita

2017-06-01

Probiotics have emerged as a promising intervention for the prevention of respiratory tract infections (RTIs) in children. Assess the effect of probiotics on prevention of RTIs in children and adolescents. MEDLINE, EMBASE, LILACS, SCIELO, CINAHL, SCOPUS, and Web of Science. Key words: "respiratory tract infections" AND probiotics. Randomized controlled trials RCT assessing the effect of probiotics on RTIs in children and adolescents were included. Two reviewers, working independently, to identify studies that met the eligibility criteria. Main and secondary outcomes were RTIs and adverse effects, respectively. Twenty-one trials with 6.603 participants were included. Pairwise meta-analysis suggested that Lactobacillus casei rhamnosus (LCA) was the only effective probiotic to the rate of RTIs compared to placebo (RR0.38; Crl 0.19-0.45). Network analysis showed that the LCA exhibited 54.7% probability of being classified in first, while the probability of Lactobacillus fermentum CECT5716 (LFC) being last in the ranking was 15.3%. LCA showed no better effect compared to other probiotic strains by indirect analysis. This systematic review found a lack of evidence to support the effect of probiotic on the incidence rate of respiratory infections in children and adolescents. Pediatr Pulmonol. 2017;52:833-843. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Security Investment in Contagious Networks.

PubMed

Hasheminasab, Seyed Alireza; Tork Ladani, Behrouz

2018-01-16

Security of the systems is normally interdependent in such a way that security risks of one part affect other parts and threats spread through the vulnerable links in the network. So, the risks of the systems can be mitigated through investments in the security of interconnecting links. This article takes an innovative look at the problem of security investment of nodes on their vulnerable links in a given contagious network as a game-theoretic model that can be applied to a variety of applications including information systems. In the proposed game model, each node computes its corresponding risk based on the value of its assets, vulnerabilities, and threats to determine the optimum level of security investments on its external links respecting its limited budget. Furthermore, direct and indirect nonlinear influences of a node's security investment on the risks of other nodes are considered. The existence and uniqueness of the game's Nash equilibrium in the proposed game are also proved. Further analysis of the model in a practical case revealed that taking advantage of the investment effects of other players, perfectly rational players (i.e., those who use the utility function of the proposed game model) make more cost-effective decisions than selfish nonrational or semirational players. © 2018 Society for Risk Analysis.

SPANNER: A Self-Repairing Spiking Neural Network Hardware Architecture.

PubMed

Liu, Junxiu; Harkin, Jim; Maguire, Liam P; McDaid, Liam J; Wade, John J

2018-04-01

Recent research has shown that a glial cell of astrocyte underpins a self-repair mechanism in the human brain, where spiking neurons provide direct and indirect feedbacks to presynaptic terminals. These feedbacks modulate the synaptic transmission probability of release (PR). When synaptic faults occur, the neuron becomes silent or near silent due to the low PR of synapses; whereby the PRs of remaining healthy synapses are then increased by the indirect feedback from the astrocyte cell. In this paper, a novel hardware architecture of Self-rePAiring spiking Neural NEtwoRk (SPANNER) is proposed, which mimics this self-repairing capability in the human brain. This paper demonstrates that the hardware can self-detect and self-repair synaptic faults without the conventional components for the fault detection and fault repairing. Experimental results show that SPANNER can maintain the system performance with fault densities of up to 40%, and more importantly SPANNER has only a 20% performance degradation when the self-repairing architecture is significantly damaged at a fault density of 80%.

Testing moderation in network meta-analysis with individual participant data.

PubMed

Dagne, Getachew A; Brown, C Hendricks; Howe, George; Kellam, Sheppard G; Liu, Lei

2016-07-10

Meta-analytic methods for combining data from multiple intervention trials are commonly used to estimate the effectiveness of an intervention. They can also be extended to study comparative effectiveness, testing which of several alternative interventions is expected to have the strongest effect. This often requires network meta-analysis (NMA), which combines trials involving direct comparison of two interventions within the same trial and indirect comparisons across trials. In this paper, we extend existing network methods for main effects to examining moderator effects, allowing for tests of whether intervention effects vary for different populations or when employed in different contexts. In addition, we study how the use of individual participant data may increase the sensitivity of NMA for detecting moderator effects, as compared with aggregate data NMA that employs study-level effect sizes in a meta-regression framework. A new NMA diagram is proposed. We also develop a generalized multilevel model for NMA that takes into account within-trial and between-trial heterogeneity and can include participant-level covariates. Within this framework, we present definitions of homogeneity and consistency across trials. A simulation study based on this model is used to assess effects on power to detect both main and moderator effects. Results show that power to detect moderation is substantially greater when applied to individual participant data as compared with study-level effects. We illustrate the use of this method by applying it to data from a classroom-based randomized study that involved two sub-trials, each comparing interventions that were contrasted with separate control groups. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Animal Social Network Theory Can Help Wildlife Conservation.

PubMed

Snijders, Lysanne; Blumstein, Daniel T; Stanley, Christina R; Franks, Daniel W

2017-08-01

Many animals preferentially associate with certain other individuals. This social structuring can influence how populations respond to changes to their environment, thus making network analysis a promising technique for understanding, predicting, and potentially manipulating population dynamics. Various network statistics can correlate with individual fitness components and key population-level processes, yet the logical role and formal application of animal social network theory for conservation and management have not been well articulated. We outline how understanding of direct and indirect relationships between animals can be profitably applied by wildlife managers and conservationists. By doing so, we aim to stimulate the development and implementation of practical tools for wildlife conservation and management and to inspire novel behavioral research in this field. Copyright © 2017 Elsevier Ltd. All rights reserved.

Disclosure strategies, social support, and quality of life in infertile women.

PubMed

Steuber, Keli R; High, Andrew

2015-07-01

Do the strategies women use to disclose information about their infertility to social network members impact the quality of the support they receive and their quality of life? The data showed that women who disclosed infertility-related information in direct ways, rather than in indirect ways (e.g. by incremental disclosures or through third parties), to social network members perceived higher quality support and reported greater quality of life related to their infertility experience. Social support has been shown to buffer stress associated with various health issues including infertility. The way people disclose information about stressors has been associated with the quality of the support they receive. Disclosing information in a way that most effectively elicits support is beneficial because women with infertility who have lower levels of stress are more likely to seek and remain in treatment. This cross-sectional study of 301 infertile women was conducted in the USA. To determine the variation in length of infertility and treatment decisions, we conducted an online survey of 301 American women coping with infertility. We investigated the strategies women used to disclose infertility-related information with social network members, their perceptions of support from friends and family, and their quality of life both in general (overall quality of life) and related to the experience of infertility (fertility quality of life). Direct disclosure of experiences related to infertility was positively and significantly associated with the perceived quality of social support received (P < 0.01). Strategies of disclosure that use entrapment or indirect media were negatively associated with fertility quality of life (P < 0.001). Directly (P < 0.01) and incremental disclosures (P < 0.01) were positively associated with overall quality of life, while the use of humor was negatively associated with overall quality of life (P < 0.01). Perceived support quality also mediated the influence of direct disclosures on women's fertility quality of life (95% CI: 0.18, 1.05) and overall quality of life (95% CI: 0.10, 0.30). This effect is particularly noteworthy for the model predicting fertility quality of life, which exhibited a non-significant main effect with direct disclosures. The non-significant main effect combined with the significant indirect effect suggests that perceived support quality fully mediates the association between direct disclosures and fertility quality of life. The cross-sectional nature of our convenient sample did not allow us to test cause and effect. It is equally plausible that women who perceive support are more likely to disclose. Longitudinal data are necessary to test the cyclic nature of these variables and confirm directionality. When women make the decision to reveal information about their infertility, direct disclosure (i.e. face-to-face, clearly, verbally and with the opportunity for an immediate response) was the only strategy that significantly corresponded with perceived support quality and was one of only two strategies that were positively associated with quality of life. To the extent that social support reduces stress, and lower stress increases the chance that people seek and stay in treatment, infertility clinics and therapists can use this information as a low-cost strategy for supporting infertile women. Scholars and practitioners can also instruct women coping with infertility about how to most effectively engage in seeking effective support. No external funding was either sought or obtained for this study and no competing interests are declared. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Ecological networks and their fragility.

PubMed

Montoya, José M; Pimm, Stuart L; Solé, Ricard V

2006-07-20

Darwin used the metaphor of a 'tangled bank' to describe the complex interactions between species. Those interactions are varied: they can be antagonistic ones involving predation, herbivory and parasitism, or mutualistic ones, such as those involving the pollination of flowers by insects. Moreover, the metaphor hints that the interactions may be complex to the point of being impossible to understand. All interactions can be visualized as ecological networks, in which species are linked together, either directly or indirectly through intermediate species. Ecological networks, although complex, have well defined patterns that both illuminate the ecological mechanisms underlying them and promise a better understanding of the relationship between complexity and ecological stability.

Correlations in the degeneracy of structurally controllable topologies for networks

NASA Astrophysics Data System (ADS)

Campbell, Colin; Aucott, Steven; Ruths, Justin; Ruths, Derek; Shea, Katriona; Albert, Réka

2017-04-01

Many dynamic systems display complex emergent phenomena. By directly controlling a subset of system components (nodes) via external intervention it is possible to indirectly control every other component in the system. When the system is linear or can be approximated sufficiently well by a linear model, methods exist to identify the number and connectivity of a minimum set of external inputs (constituting a so-called minimal control topology, or MCT). In general, many MCTs exist for a given network; here we characterize a broad ensemble of empirical networks in terms of the fraction of nodes and edges that are always, sometimes, or never a part of an MCT. We study the relationships between the measures, and apply the methodology to the T-LGL leukemia signaling network as a case study. We show that the properties introduced in this report can be used to predict key components of biological networks, with potentially broad applications to network medicine.

Graphical tools for network meta-analysis in STATA.

PubMed

Chaimani, Anna; Higgins, Julian P T; Mavridis, Dimitris; Spyridonos, Panagiota; Salanti, Georgia

2013-01-01

Network meta-analysis synthesizes direct and indirect evidence in a network of trials that compare multiple interventions and has the potential to rank the competing treatments according to the studied outcome. Despite its usefulness network meta-analysis is often criticized for its complexity and for being accessible only to researchers with strong statistical and computational skills. The evaluation of the underlying model assumptions, the statistical technicalities and presentation of the results in a concise and understandable way are all challenging aspects in the network meta-analysis methodology. In this paper we aim to make the methodology accessible to non-statisticians by presenting and explaining a series of graphical tools via worked examples. To this end, we provide a set of STATA routines that can be easily employed to present the evidence base, evaluate the assumptions, fit the network meta-analysis model and interpret its results.

Graphical Tools for Network Meta-Analysis in STATA

PubMed Central

Chaimani, Anna; Higgins, Julian P. T.; Mavridis, Dimitris; Spyridonos, Panagiota; Salanti, Georgia

2013-01-01

Network meta-analysis synthesizes direct and indirect evidence in a network of trials that compare multiple interventions and has the potential to rank the competing treatments according to the studied outcome. Despite its usefulness network meta-analysis is often criticized for its complexity and for being accessible only to researchers with strong statistical and computational skills. The evaluation of the underlying model assumptions, the statistical technicalities and presentation of the results in a concise and understandable way are all challenging aspects in the network meta-analysis methodology. In this paper we aim to make the methodology accessible to non-statisticians by presenting and explaining a series of graphical tools via worked examples. To this end, we provide a set of STATA routines that can be easily employed to present the evidence base, evaluate the assumptions, fit the network meta-analysis model and interpret its results. PMID:24098547

Embedded resource accounting for coupled natural-human systems: An application to water resource impacts of the western U.S. electrical energy trade

NASA Astrophysics Data System (ADS)

Ruddell, Benjamin L.; Adams, Elizabeth A.; Rushforth, Richard; Tidwell, Vincent C.

2014-10-01

In complex coupled natural-human systems (CNH), multitype networks link social, environmental, and economic systems with flows of matter, energy, information, and value. Embedded Resource Accounting (ERA) is a systems analysis framework that includes the indirect connections of a multitype CNH network. ERA is conditioned on perceived system boundaries, which may vary according to the accountant's point of view. Both direct and indirect impacts are implicit whenever two subnetworks interact in such a system; the ratio of two subnetworks' impacts is the embedded intensity. For trade in the services of water, this is understood as the indirect component of a water footprint, and as "virtual water" trade. ERA is a generalization of input-output, footprint, and substance flow methods, and is a type of life cycle analysis. This paper presents results for the water and electrical energy system in the western U.S. This system is dominated by California, which outsources the majority of its water footprint of electrical energy. Electricity trade increases total water consumption for electricity production in the western U.S. by 15% and shifts water use to water-stressed Colorado River Basin States. A systemic underaccounting for water footprints occurs because state-level processes discount a portion of the water footprint occurring outside of the state boundary.

Perceptions of physical and social environment variables and self-efficacy as correlates of self-reported physical activity among adolescent girls.

PubMed

Motl, Robert W; Dishman, Rod K; Saunders, Ruth P; Dowda, Marsha; Pate, Russell R

2007-01-01

This cross-sectional study examined the direct and indirect effects of perceived equipment accessibility, neighborhood safety, and social support on self-reported physical activity among older adolescent girls. Adolescent girls (n = 1,655) who were in the 12th grade completed a battery of questionnaires that included self-report measures of the perceived physical environment, social support, barriers self-efficacy, and physical activity. Perceived neighborhood safety did not exhibit direct or indirect effects on self-reported physical activity. Perceived equipment accessibility exhibited an indirect effect on self-reported physical activity that was accounted for by barriers self-efficacy. Perceived social support exhibited direct and indirect effects on self-reported physical activity; the indirect effect was accounted for by barriers self-efficacy. The relationships were independent of parental education and body mass index (BMI). Perceived physical environmental factors indirectly influenced self-reported physical activity, and perceived social environmental factors both directly and indirectly influenced self-reported physical activity in this sample of older adolescent girls.

[Euthanasia and the doctrine of double effect].

PubMed

Klein, Martin

2005-01-01

Direct active euthanasia is prohibited in most countries while passive and indirect is not. However, many arguments against the legalization of voluntary active euthanasia are flawed. Ethical differences between active and passive or indirect euthanasia are difficult to maintain especially when the passivity of the actor causes death. The crucial point is not activity or passivity but respect for the autonomy of individual human beings. In particular there appears to be little ethical difference between active and indirect euthanasia. Indirect euthanasia has often been justified by the principle of double effect, which traces back to Thomas Aquinas. But resorting to this rule contains a logical fallacy. The principle of double effect does not allow foreseen and unwanted adverse effects of an action to occur when they are avoidable. In terminal sedation, an example for indirect euthanasia, hypoxemia and dehydration can easily be prevented by respirator therapy and fluid administration. Therefore the rule of double effect is not applicable. Indirect and direct active euthanasia cannot be ethically distinguished by resorting to the principle of double effect.

Therapeutic effects of different drugs on obstructive sleep apnea/hypopnea syndrome in children.

PubMed

Zhang, Jing; Chen, Jie; Yin, Yong; Zhang, Lei; Zhang, Hao

2017-12-01

This study aimed to compare the therapeutic effects of different drugs on obstructive sleep apnea/hypopnea syndrome (OSAHS) in children by using a network meta-analysis approach. PubMed, Embase and Cochrane Library were searched from the inception of each database to November 2015. Randomized controlled trials (RCTs) concerning the comparisons in the therapeutic effects of eight placebo-controlled drugs on OSAHS in children were included in this study. Network meta-analysis combined direct evidence and indirect evidence to evaluate the weighted mean difference (WMD) and surface under the cumulative ranking curves (SUCRA) of therapeutic effects of eight drugs on OSAHS in children. A total of seven RCTs were finally incorporated into our network meta-analysis. Pairwise meta-analysis results revealed that therapeutic effect of placebo was significantly poorer than that of intranasal mometasone furoate, montelukast, budesonide and fluticasone concerning apnea hypopnea index (AHI) value [WMD=1.40, 95% confidence interval (CI)=1.17-1.63; WMD=2.80, 95% CI=1.01-4.59; WMD=3.50, 95% CI=3.34-3.66; WMD=7.20, 95% CI=5.26-9.14, respectively], and fluticasone is better than placebo concerning sleep efficiency (WMD=3.50, 95% CI=2.42-4.58); regarding visual analogue scale, the therapeutic effect of placebo was poorer compared with sucralfate and clindamycin (WMD=1.94, 95% CI=1.13-2.75; WMD=1.06, 95% CI=0.22-1.90), and sucralfate is better than clindamycin (WMD=-0.88, 95% CI=-1.65 to -0.11). However, network meta-analysis results showed no obvious difference in the therapeutic effects of different drugs on OSAHS regarding AHI and sleep efficiency. Furthermore, the best SUCRA value was very high for fluticasone concerning AHI (86.6%) and budesonide concerning sleep efficiency (94.0%) for OSAHS treatment. Fluticasone and budesonide have relatively good effects in the treatment of OSAHS in children, thus providing an important guiding significance for the treatment of OSAHS in children.

Citation Patterns in the Computer-Based Instruction Literature.

ERIC Educational Resources Information Center

Wedman, John F.

1987-01-01

This study examined indirect communication patterns among professionals in the computer-based instruction field by analyzing citations from the Journal of Computer-Based Instruction. The patterns found provide the basis for identifying invisible colleges, defined here as communication networks that facilitate the diffusion of knowledge and direct…

Virtual phosphorus ore requirement of Japanese economy.

PubMed

Matsubae, Kazuyo; Kajiyama, Jun; Hiraki, Takehito; Nagasaka, Tetsuya

2011-08-01

Phosphorus is indispensable for agricultural production. Hence, the consumption of imported food indirectly implies the import of phosphorus resources. The global consumption of agricultural products depends on a small number of ore-producing countries. For sustainable management of phosphorus resources, the global supply and demand network should be clarified. In this study, we propose the virtual phosphorus ore requirement as a new indicator of the direct and indirect phosphorus requirements for our society. The virtual phosphorus ore requirement indicates the direct and indirect demands for phosphorus ore transformed into agricultural products and fertilizer. In this study, the virtual phosphorus ore requirement was evaluated for the Japanese economy in 2005. Importantly, the results show that our society requires twice as much phosphorus ore as the domestic demand for fertilizer production. The phosphorus contained in "eaten" agricultural products was only 12% of virtual phosphorus ore requirement. Copyright © 2011 Elsevier Ltd. All rights reserved.

Direct and indirect urban water footprints of the United States

NASA Astrophysics Data System (ADS)

Chini, Christopher M.; Konar, Megan; Stillwell, Ashlynn S.

2017-01-01

The water footprint of the urban environment is not limited to direct water consumption (i.e., municipal supplies); embedded water in imported resources, or virtual water transfers, provides an additional component of the urban water footprint. Using empirical data, our analysis extends traditional urban water footprinting analysis to quantify both direct and indirect urban resources for the United States. We determine direct water volumes and their embedded energy through open records requests of water utilities. The indirect component of the urban water footprint includes water indirectly consumed through energy and food, relating to the food-energy-water nexus. We comprehensively quantify the indirect water footprint for 74 metropolitan statistical areas through the combination of various databases, including the Commodity Flow Survey of the U.S. Census Bureau, the U.S. Department of Agriculture, the Water Footprint Network, and the Energy Information Administration. We then analyze spatial heterogeneity in both direct and indirect water footprints, determining the average urban water footprint in the United States to be 1.64 million gallons of water per person per year [6200 m3/person/yr or 17,000 L/person/d], dominated by indirect water. Additionally, our study of the urban water cycle extends beyond considering only water resources to include embedded energy and equivalent carbon dioxide emissions. The inclusion of multiple sectors of the urban water cycle and their underlying processes provides important insights to the overall urban environment, the interdependencies of the food-energy-water nexus, and water resource sustainability. Our results provide opportunities for benchmarking the urban energy-water nexus, water footprints, and climate change potential.

Aripiprazole Lauroxil Compared with Paliperidone Palmitate in Patients with Schizophrenia: An Indirect Treatment Comparison.

PubMed

Cameron, Chris; Zummo, Jacqueline; Desai, Dharmik N; Drake, Christine; Hutton, Brian; Kotb, Ahmed; Weiden, Peter J

Aripiprazole lauroxil (AL) is a long-acting injectable atypical antipsychotic recently approved for treatment of schizophrenia on the basis of a large-scale trial of two doses of AL versus placebo. There are no direct-comparison studies with paliperidone palmitate (PP; long-acting antipsychotic used most often in acute settings) for the acute psychotic episode. To indirectly compare efficacy and safety of the pivotal AL study with all PP studies meeting indirect comparison criteria. Systematic searches of MEDLINE, Embase, Cochrane CENTRAL, PsycINFO, ClinicalTrials.gov, International Clinical Trials Registry Platform, and gray literature were performed to identify randomized controlled trials of PP with similar designs to the AL trial. Bayesian network meta-analysis compared treatments with respect to symptom response and tolerability issues including weight gain, akathisia, parkinsonism, and likelihood of treatment-emergent adverse events. Three appropriate PP studies were identified for indirect comparison. Both doses of AL (441 mg and 882 mg monthly) were used and compared with two efficacious doses of PP (156 mg and 234 mg monthly). All four active-treatment conditions were associated with comparable reductions in acute symptoms (Positive and Negative Syndrome Scale) versus placebo and were of similar magnitude (range of mean difference -8.12 to -12.01, with overlapping 95% credible intervals). Between-group comparisons of active-treatment arms were associated with summary estimates of magnitude near 0. No clinically meaningful differences in selected safety or tolerability parameter incidence were found between active treatments. These results suggest that both AL and PP are effective for treatment of adults experiencing acute exacerbation of schizophrenia. Copyright © 2017 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

Indirect diagnosis of pavement structural damages using surface GPR reflection techniques

NASA Astrophysics Data System (ADS)

Benedetto, A.; Pensa, S.

2007-06-01

The safety and operability of road networks is, in part, dependent on the quality of the pavement. It is known that pavements suffer from many different structural problems which can lead to damage to the pavement surface. To minimize the effect of these problems programmed policies for pavement management are required. Additionally a given local anomaly on the road surface can affect the safety of the road to various degrees according to the category of the road, so it is possible to set up different programmes of repair according to the different standards of road. Programmed policies for pavement management are required because of the wide structural damage which occurs to pavements during their normal operating life. This has consequences for the safety and operability of road networks. During the last decade, road networks suffered from great structural damage. The damage occurs for different reasons, such as the increasing traffic or the lack of means for routine maintenance. Many forms of damage, originating in the bottom layers are invisible until the pavement cracks. They depend on the infiltration of water and the presence of cohesive soil greatly reduces the bearing capacity of the sub-asphalt layers and underlying soils. On the basis of an in-depth literature review, an experimental survey with Ground Penetrating Radar (GPR) was carried out to calibrate the geophysical parameters and to validate the reliability of an indirect diagnostic method of pavement damage. The experiments were set on a pavement under which water was injected over a period of several hours. GPR travel time data were used to estimate the dielectric constant and the water content in the unbound aggregate layer, the variations in water content with time and particular areas where rate of infiltration decreases. A new methodology has been proposed to extract the hydraulic permittivity fields in sub-asphalt structural layers and soils from the moisture maps observed with GPR. It is effective at diagnosing the presence of clay or cohesive soil that compromises the bearing capacity of sub-base and induces damage.

[Comparison of serological procedures used for the diagnosis of viral exanthema in laboratories participating in the measles elimination plan].

PubMed

de Ory, Fernando; Sanz, Juan Carlos; Echevarría, Juan Emilio; Mosquera, María del Mar; Guisasola, María Eulalia

2004-01-01

The comparison of serological methods used by the laboratories participating in the Network for the Elimination of Measles to diagnose measles virus infection as well as differential diagnosis with other exanthematic diseases are compared. One panel of 20 serum samples including measles (12), rubella (4), parvovirus B19 (2) and dengue (2) infections was established. All cases were diagnosed by detection of specific IgM. The panel was sent to the laboratories of the Network. The results were compared with those obtained at the reference laboratory. Regarding measles, IgM response from 20 laboratories (19 by ELISA and 1 by indirect immunofluorescence) was obtained, with an agreement of 91.5%. Related to rubella IgM, replay from 6 laboratories, using ELISA, was received, with an agreement of 98.7%. With respect to parvovirus B19 IgM, response from 10 laboratories (8 by ELISA and 2 by indirect immunofluorescence) was obtained, with an agreement of 94.6%. Results about dengue virus were not reported by any laboratory. Some laboratories from the network should review the methods used for the diagnosis of measles and other exanthematic diseases. The results reassert the need for a reference laboratory to support confirmation of the results.

The neural correlates of obsessive-compulsive disorder: a multimodal perspective.

PubMed

Moreira, P S; Marques, P; Soriano-Mas, C; Magalhães, R; Sousa, N; Soares, J M; Morgado, P

2017-08-29

Obsessive-compulsive disorder (OCD) is one of the most debilitating psychiatric conditions. An extensive body of the literature has described some of the neurobiological mechanisms underlying the core manifestations of the disorder. Nevertheless, most reports have focused on individual modalities of structural/functional brain alterations, mainly through targeted approaches, thus possibly precluding the power of unbiased exploratory approaches. Eighty subjects (40 OCD and 40 healthy controls) participated in a multimodal magnetic resonance imaging (MRI) investigation, integrating structural and functional data. Voxel-based morphometry analysis was conducted to compare between-group volumetric differences. The whole-brain functional connectome, derived from resting-state functional connectivity (FC), was analyzed with the network-based statistic methodology. Results from structural and functional analysis were integrated in mediation models. OCD patients revealed volumetric reductions in the right superior temporal sulcus. Patients had significantly decreased FC in two distinct subnetworks: the first, involving the orbitofrontal cortex, temporal poles and the subgenual anterior cingulate cortex; the second, comprising the lingual and postcentral gyri. On the opposite, a network formed by connections between thalamic and occipital regions had significantly increased FC in patients. Integrative models revealed direct and indirect associations between volumetric alterations and FC networks. This study suggests that OCD patients display alterations in brain structure and FC, involving complex networks of brain regions. Furthermore, we provided evidence for direct and indirect associations between structural and functional alterations representing complex patterns of interactions between separate brain regions, which may be of upmost relevance for explaining the pathophysiology of the disorder.

Seismic Attenuation and Stiffness Modulus Dispersion in Porous Rocks Containing Stochastic Fracture Networks

NASA Astrophysics Data System (ADS)

Hunziker, Jürg; Favino, Marco; Caspari, Eva; Quintal, Beatriz; Rubino, J. Germán.; Krause, Rolf; Holliger, Klaus

2018-01-01

Understanding seismic attenuation and modulus dispersion mechanisms in fractured rocks can result in significant advances for the indirect characterization of such environments. In this paper, we study attenuation and modulus dispersion of seismic waves caused by fluid pressure diffusion (FPD) in stochastic 2-D fracture networks, allowing for a state-of-the-art representation of natural fracture networks by a power law length distribution. To this end, we apply numerical upscaling experiments consisting of compression and shear tests to our samples of fractured rocks. The resulting P and S wave attenuation and modulus dispersion behavior is analyzed with respect to the density, the length distribution, and the connectivity of the fractures. We focus our analysis on two manifestations of FPD arising in fractured rocks, namely, fracture-to-background FPD at lower frequencies and fracture-to-fracture FPD at higher frequencies. Our results indicate that FPD is sensitive not only to the fracture density but also to the geometrical characteristics of the fracture length distributions. In particular, our study suggests that information about the local connectivity of a fracture network could be retrieved from seismic data. Conversely, information about the global connectivity, which is directly linked to the effective hydraulic conductivity of the probed volume, remains rather difficult to infer.

Identification of cancer-related miRNA-lncRNA biomarkers using a basic miRNA-lncRNA network.

PubMed

Zhang, Guangle; Pian, Cong; Chen, Zhi; Zhang, Jin; Xu, Mingmin; Zhang, Liangyun; Chen, Yuanyuan

2018-01-01

LncRNAs are regulatory noncoding RNAs that play crucial roles in many biological processes. The dysregulation of lncRNA is thought to be involved in many complex diseases; lncRNAs are often the targets of miRNAs in the indirect regulation of gene expression. Numerous studies have indicated that miRNA-lncRNA interactions are closely related to the occurrence and development of cancers. Thus, it is important to develop an effective method for the identification of cancer-related miRNA-lncRNA interactions. In this study, we compiled 155653 experimentally validated and predicted miRNA-lncRNA associations, which we defined as basic interactions. We next constructed an individual-specific miRNA-lncRNA network (ISMLN) for each cancer sample and a basic miRNA-lncRNA network (BMLN) for each type of cancer by examining the expression profiles of miRNAs and lncRNAs in the TCGA (The Cancer Genome Atlas) database. We then selected potential miRNA-lncRNA biomarkers based on the BLMN. Using this method, we identified cancer-related miRNA-lncRNA biomarkers and modules specific to a certain cancer. This method of profiling will contribute to the diagnosis and treatment of cancers at the level of gene regulatory networks.

Unpacking Direct and Indirect Relationships of Short-Term Memory to Word Reading: Evidence From Korean-Speaking Children.

PubMed

Kim, Young-Suk Grace; Cho, Jeung-Ryeul; Park, Soon-Gil

2017-08-01

We examined the relations of short-term memory (STM), metalinguistic awareness (phonological, morphological, and orthographic awareness), and rapid automatized naming (RAN) to word reading in Korean, a language with a relatively transparent orthography. STM, metalinguistic awareness, and RAN have been shown to be important to word reading, but the nature of the relations of STM, metalinguistic awareness, and RAN to word reading has rarely been investigated. Two alternative models were fitted. In the indirect relation model, STM was hypothesized to be indirectly related to word reading via metalinguistic awareness and RAN. In the direct and indirect relations model, STM was hypothesized to be directly and indirectly related to word reading. Results from 207 beginning readers in South Korea showed that STM was directly related to word reading as well as indirectly via metalinguistic awareness and RAN. Although the direct effect of STM was relatively small (.16), the total effect incorporating the indirect effect was substantial (.42). These results suggest that STM is an important, foundational cognitive capacity that underpins metalinguistic awareness and RAN as well as word reading, and further indicate the importance of considering both direct and indirect effects of language and cognitive skills on word reading.

Plumage condition in laying hens: genetic parameters for direct and indirect effects in two purebred layer lines.

PubMed

Brinker, Tessa; Bijma, Piter; Visscher, Jeroen; Rodenburg, T Bas; Ellen, Esther D

2014-05-29

Feather pecking is a major welfare issue in laying hen industry that leads to mortality. Due to a ban on conventional cages in the EU and on beak trimming in some countries of the EU, feather pecking will become an even bigger problem. Its severity depends both on the victim receiving pecking and on its group mates inflicting pecking (indirect effects), which together determine plumage condition of the victim. Plumage condition may depend, therefore, on both the direct genetic effect of an individual itself and on the indirect genetic effects of its group mates. Here, we present estimated genetic parameters for direct and indirect effects on plumage condition of different body regions in two purebred layer lines, and estimates of genetic correlations between body regions. Feather condition scores (FCS) were recorded at 40 weeks of age for neck, back, rump and belly and these four scores were added-up into a total FCS. A classical animal model and a direct-indirect effects model were used to estimate genetic parameters for FCS. In addition, a bivariate model with mortality (0/1) was used to account for mortality before recording FCS. Due to mortality during the first 23 weeks of laying, 5363 (for W1) and 5089 (for WB) FCS records were available. Total heritable variance for FCS ranged from 1.5% to 9.8% and from 9.8% to 53.6% when estimated respectively with the classical animal and the direct-indirect effects model. The direct-indirect effects model had a significantly higher likelihood. In both lines, 70% to 94% of the estimated total heritable variation in FCS was due to indirect effects. Using bivariate analysis of FCS and mortality did not affect estimates of genetic parameters. Genetic correlations were high between adjacent regions for FCS on neck, back, and rump but moderate to low for belly with other regions. Our results show that 70% to 94% of the heritable variation in FCS relates to indirect effects, indicating that methods of genetic selection that include indirect genetic effects offer perspectives to improve plumage condition in laying hens. This, in turn could reduce a major welfare problem.

Assessing Mediational Models: Testing and Interval Estimation for Indirect Effects

ERIC Educational Resources Information Center

Biesanz, Jeremy C.; Falk, Carl F.; Savalei, Victoria

2010-01-01

Theoretical models specifying indirect or mediated effects are common in the social sciences. An indirect effect exists when an independent variable's influence on the dependent variable is mediated through an intervening variable. Classic approaches to assessing such mediational hypotheses (Baron & Kenny, 1986; Sobel, 1982) have in recent years…

Indirect effect of management support on users' compliance behaviour towards information security policies.

PubMed

Humaidi, Norshima; Balakrishnan, Vimala

2018-01-01

Health information systems are innovative products designed to improve the delivery of effective healthcare, but they are also vulnerable to breaches of information security, including unauthorised access, use, disclosure, disruption, modification or destruction, and duplication of passwords. Greater openness and multi-connectedness between heterogeneous stakeholders within health networks increase the security risk. The focus of this research was on the indirect effects of management support (MS) on user compliance behaviour (UCB) towards information security policies (ISPs) among health professionals in selected Malaysian public hospitals. The aim was to identify significant factors and provide a clearer understanding of the nature of compliance behaviour in the health sector environment. Using a survey design and stratified random sampling method, self-administered questionnaires were distributed to 454 healthcare professionals in three hospitals. Drawing on theories of planned behaviour, perceived behavioural control (self-efficacy (SE) and MS components) and the trust factor, an information system security policies compliance model was developed to test three related constructs (MS, SE and perceived trust (PT)) and their relationship to UCB towards ISPs. Results showed a 52.8% variation in UCB through significant factors. Partial least squares structural equation modelling demonstrated that all factors were significant and that MS had an indirect effect on UCB through both PT and SE among respondents to this study. The research model based on the theory of planned behaviour in combination with other human and organisational factors has made a useful contribution towards explaining compliance behaviour in relation to organisational ISPs, with trust being the most significant factor. In adopting a multidimensional approach to management-user interactions via multidisciplinary concepts and theories to evaluate the association between the integrated management-user values and the nature of compliance towards ISPs among selected health professionals, this study has made a unique contribution to the literature.

Comparing Indirect Effects in SEM: A Sequential Model Fitting Method Using Covariance-Equivalent Specifications

ERIC Educational Resources Information Center

Chan, Wai

2007-01-01

In social science research, an indirect effect occurs when the influence of an antecedent variable on the effect variable is mediated by an intervening variable. To compare indirect effects within a sample or across different samples, structural equation modeling (SEM) can be used if the computer program supports model fitting with nonlinear…

Integrative approach for inference of gene regulatory networks using lasso-based random featuring and application to psychiatric disorders.

PubMed

Kim, Dongchul; Kang, Mingon; Biswas, Ashis; Liu, Chunyu; Gao, Jean

2016-08-10

Inferring gene regulatory networks is one of the most interesting research areas in the systems biology. Many inference methods have been developed by using a variety of computational models and approaches. However, there are two issues to solve. First, depending on the structural or computational model of inference method, the results tend to be inconsistent due to innately different advantages and limitations of the methods. Therefore the combination of dissimilar approaches is demanded as an alternative way in order to overcome the limitations of standalone methods through complementary integration. Second, sparse linear regression that is penalized by the regularization parameter (lasso) and bootstrapping-based sparse linear regression methods were suggested in state of the art methods for network inference but they are not effective for a small sample size data and also a true regulator could be missed if the target gene is strongly affected by an indirect regulator with high correlation or another true regulator. We present two novel network inference methods based on the integration of three different criteria, (i) z-score to measure the variation of gene expression from knockout data, (ii) mutual information for the dependency between two genes, and (iii) linear regression-based feature selection. Based on these criterion, we propose a lasso-based random feature selection algorithm (LARF) to achieve better performance overcoming the limitations of bootstrapping as mentioned above. In this work, there are three main contributions. First, our z score-based method to measure gene expression variations from knockout data is more effective than similar criteria of related works. Second, we confirmed that the true regulator selection can be effectively improved by LARF. Lastly, we verified that an integrative approach can clearly outperform a single method when two different methods are effectively jointed. In the experiments, our methods were validated by outperforming the state of the art methods on DREAM challenge data, and then LARF was applied to inferences of gene regulatory network associated with psychiatric disorders.

Complex networks of functional connectivity in a wetland reconnected to its floodplain

USGS Publications Warehouse

Larsen, Laurel G.; Newman, Susan; Saunders, Colin; Harvey, Judson

2017-01-01

Disturbances such as fire or flood, in addition to changing the local magnitude of ecological, hydrological, or biogeochemical processes, can also change their functional connectivity—how those processes interact in space. Complex networks offer promise for quantifying functional connectivity in watersheds. The approach resolves connections between nodes in space based on statistical similarities in perturbation signals (derived from solute time series) and is sensitive to a wider range of timescales than traditional mass-balance modeling. We use this approach to test hypotheses about how fire and flood impact ecological and biogeochemical dynamics in a wetland (Everglades, FL, USA) that was reconnected to its floodplain. Reintroduction of flow pulses after decades of separation by levees fundamentally reconfigured functional connectivity networks. The most pronounced expansion was that of the calcium network, which reflects periphyton dynamics and may represent an indirect influence of elevated nutrients, despite the comparatively smaller observed expansion of phosphorus networks. With respect to several solutes, periphyton acted as a “biotic filter,” shifting perturbations in water-quality signals to different timescales through slow but persistent transformations of the biotic community. The complex-networks approach also revealed portions of the landscape that operate in fundamentally different regimes with respect to dissolved oxygen, separated by a threshold in flow velocity of 1.2 cm/s, and suggested that complete removal of canals may be needed to restore connectivity with respect to biogeochemical processes. Fire reconfigured functional connectivity networks in a manner that reflected localized burn severity, but had a larger effect on the magnitude of solute concentrations.

QuIN: A Web Server for Querying and Visualizing Chromatin Interaction Networks.

PubMed

Thibodeau, Asa; Márquez, Eladio J; Luo, Oscar; Ruan, Yijun; Menghi, Francesca; Shin, Dong-Guk; Stitzel, Michael L; Vera-Licona, Paola; Ucar, Duygu

2016-06-01

Recent studies of the human genome have indicated that regulatory elements (e.g. promoters and enhancers) at distal genomic locations can interact with each other via chromatin folding and affect gene expression levels. Genomic technologies for mapping interactions between DNA regions, e.g., ChIA-PET and HiC, can generate genome-wide maps of interactions between regulatory elements. These interaction datasets are important resources to infer distal gene targets of non-coding regulatory elements and to facilitate prioritization of critical loci for important cellular functions. With the increasing diversity and complexity of genomic information and public ontologies, making sense of these datasets demands integrative and easy-to-use software tools. Moreover, network representation of chromatin interaction maps enables effective data visualization, integration, and mining. Currently, there is no software that can take full advantage of network theory approaches for the analysis of chromatin interaction datasets. To fill this gap, we developed a web-based application, QuIN, which enables: 1) building and visualizing chromatin interaction networks, 2) annotating networks with user-provided private and publicly available functional genomics and interaction datasets, 3) querying network components based on gene name or chromosome location, and 4) utilizing network based measures to identify and prioritize critical regulatory targets and their direct and indirect interactions. QuIN's web server is available at http://quin.jax.org QuIN is developed in Java and JavaScript, utilizing an Apache Tomcat web server and MySQL database and the source code is available under the GPLV3 license available on GitHub: https://github.com/UcarLab/QuIN/.

Complex networks of functional connectivity in a wetland reconnected to its floodplain

NASA Astrophysics Data System (ADS)

Larsen, Laurel G.; Newman, Susan; Saunders, Colin; Harvey, Judson W.

2017-07-01

Disturbances such as fire or flood, in addition to changing the local magnitude of ecological, hydrological, or biogeochemical processes, can also change their functional connectivity—how those processes interact in space. Complex networks offer promise for quantifying functional connectivity in watersheds. The approach resolves connections between nodes in space based on statistical similarities in perturbation signals (derived from solute time series) and is sensitive to a wider range of timescales than traditional mass-balance modeling. We use this approach to test hypotheses about how fire and flood impact ecological and biogeochemical dynamics in a wetland (Everglades, FL, USA) that was reconnected to its floodplain. Reintroduction of flow pulses after decades of separation by levees fundamentally reconfigured functional connectivity networks. The most pronounced expansion was that of the calcium network, which reflects periphyton dynamics and may represent an indirect influence of elevated nutrients, despite the comparatively smaller observed expansion of phosphorus networks. With respect to several solutes, periphyton acted as a "biotic filter," shifting perturbations in water-quality signals to different timescales through slow but persistent transformations of the biotic community. The complex-networks approach also revealed portions of the landscape that operate in fundamentally different regimes with respect to dissolved oxygen, separated by a threshold in flow velocity of 1.2 cm/s, and suggested that complete removal of canals may be needed to restore connectivity with respect to biogeochemical processes. Fire reconfigured functional connectivity networks in a manner that reflected localized burn severity, but had a larger effect on the magnitude of solute concentrations.

Linking social and pathogen transmission networks using microbial genetics in giraffe (Giraffa camelopardalis).

PubMed

VanderWaal, Kimberly L; Atwill, Edward R; Isbell, Lynne A; McCowan, Brenda

2014-03-01

Although network analysis has drawn considerable attention as a promising tool for disease ecology, empirical research has been hindered by limitations in detecting the occurrence of pathogen transmission (who transmitted to whom) within social networks. Using a novel approach, we utilize the genetics of a diverse microbe, Escherichia coli, to infer where direct or indirect transmission has occurred and use these data to construct transmission networks for a wild giraffe population (Giraffe camelopardalis). Individuals were considered to be a part of the same transmission chain and were interlinked in the transmission network if they shared genetic subtypes of E. coli. By using microbial genetics to quantify who transmits to whom independently from the behavioural data on who is in contact with whom, we were able to directly investigate how the structure of contact networks influences the structure of the transmission network. To distinguish between the effects of social and environmental contact on transmission dynamics, the transmission network was compared with two separate contact networks defined from the behavioural data: a social network based on association patterns, and a spatial network based on patterns of home-range overlap among individuals. We found that links in the transmission network were more likely to occur between individuals that were strongly linked in the social network. Furthermore, individuals that had more numerous connections or that occupied 'bottleneck' positions in the social network tended to occupy similar positions in the transmission network. No similar correlations were observed between the spatial and transmission networks. This indicates that an individual's social network position is predictive of transmission network position, which has implications for identifying individuals that function as super-spreaders or transmission bottlenecks in the population. These results emphasize the importance of association patterns in understanding transmission dynamics, even for environmentally transmitted microbes like E. coli. This study is the first to use microbial genetics to construct and analyse transmission networks in a wildlife population and highlights the potential utility of an approach integrating microbial genetics with network analysis. © 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.

People will talk.

PubMed

Chan, Steven D

2012-01-01

The rise of the social media phenomenon and its impact on dentistry are discussed in the paper. The relationship between dentists and patients is growing wider and more indirect. Social media can be roughly characterized in five categories: social, reference, review, coupon, and information networks. Opportunities and threats posed by social media are explored.

Network analysis: a new tool for resource managers

Treesearch

Ruth H. Allen

1980-01-01

Resource managers manipulate ecosystems for direct or indirect human uses. Examples of relatively well studied resource management issues include familiar biological products such as: forests, ranges, fish and wildlife; or physical products such as air, water and soil. Until very recently, urban environments received much less scholarly attention. However, as Spurr (...

47 CFR 25.272 - General inter-system coordination procedures.

Code of Federal Regulations, 2011 CFR

2011-10-01

... network control center which will have the responsibility to monitor space-to-Earth transmissions in its system. This would indirectly monitor uplink earth station transmissions in its system and to coordinate.... (c) The transmitting earth station licensee shall provide the operator(s) of the satellites, on which...

47 CFR 25.272 - General inter-system coordination procedures.

Code of Federal Regulations, 2012 CFR

2012-10-01

... network control center which will have the responsibility to monitor space-to-Earth transmissions in its system. This would indirectly monitor uplink earth station transmissions in its system and to coordinate.... (c) The transmitting earth station licensee shall provide the operator(s) of the satellites, on which...

47 CFR 25.272 - General inter-system coordination procedures.

Code of Federal Regulations, 2014 CFR

2014-10-01

... network control center which will have the responsibility to do the following: (1) Monitor space-to-Earth transmissions in its system (thus indirectly monitoring uplink earth station transmissions in its system) and (2... and correct the problem promptly. (b) [Reserved] (c) The transmitting earth station licensee shall...

47 CFR 25.272 - General inter-system coordination procedures.

Code of Federal Regulations, 2013 CFR

2013-10-01

... network control center which will have the responsibility to do the following: (1) Monitor space-to-Earth transmissions in its system (thus indirectly monitoring uplink earth station transmissions in its system) and (2... issues. (c) The transmitting earth station licensee shall provide the operator(s) of the satellites, on...

On Tradeoffs between Trust Accuracy and Resource Consumption in Communications and Social Networks

DTIC Science & Technology

2016-04-11

length, the use of indirect information to establish trust values, and the impact of misbehaving nodes on both communication overhead and the...evaluated). We consider the impact of misbehaving (selfish or malicious) nodes on the evaluation of trust. We also consider the interaction between

Posttraumatic Stress Disorder and Suicidal Behavior: Indirect Effects of Impaired Social Functioning.

PubMed

Dutton, Courtney E; Rojas, Sasha M; Badour, Christal L; Wanklyn, Sonya G; Feldner, Matthew T

2016-01-01

Social functioning is negatively impacted by the presence of PTSD, while increasing risk of suicidal behavior among individuals with PTSD. However, little research has examined the specific role of social functioning in the association between PTSD and suicidal behavior. Parallel multiple indirect effects analyses were performed to understand the unique indirect effects of four aspects of social functioning. Indirect effects of PTSD on suicidal ideation were significant through three pathways: interpersonal conflict, perceived family support, and interpersonal apprehension. Perceived family support was the only indirect pathway significantly associated with suicide attempt. Findings suggest that social functioning should be assessed and potentially targeted during treatment to help modify the risk for suicidal behavior among individuals with PTSD.

Feedbacks between air pollution and weather, part 2: Effects on chemistry

NASA Astrophysics Data System (ADS)

Makar, P. A.; Gong, W.; Hogrefe, C.; Zhang, Y.; Curci, G.; Žabkar, R.; Milbrandt, J.; Im, U.; Balzarini, A.; Baró, R.; Bianconi, R.; Cheung, P.; Forkel, R.; Gravel, S.; Hirtl, M.; Honzak, L.; Hou, A.; Jiménez-Guerrero, P.; Langer, M.; Moran, M. D.; Pabla, B.; Pérez, J. L.; Pirovano, G.; San José, R.; Tuccella, P.; Werhahn, J.; Zhang, J.; Galmarini, S.

2015-08-01

Fully-coupled air-quality models running in ;feedback; and ;no-feedback; configurations were compared against each other and observation network data as part of Phase 2 of the Air Quality Model Evaluation International Initiative. In the ;no-feedback; mode, interactions between meteorology and chemistry through the aerosol direct and indirect effects were disabled, with the models reverting to climatologies of aerosol properties, or a no-aerosol weather simulation, while in the ;feedback; mode, the model-generated aerosols were allowed to modify the models' radiative transfer and/or cloud formation processes. Annual simulations with and without feedbacks were conducted for domains in North America for the years 2006 and 2010, and for Europe for the year 2010. Comparisons against observations via annual statistics show model-to-model variation in performance is greater than the within-model variation associated with feedbacks. However, during the summer and during intense emission events such as the Russian forest fires of 2010, feedbacks have a significant impact on the chemical predictions of the models. The aerosol indirect effect was usually found to dominate feedbacks compared to the direct effect. The impacts of direct and indirect effects were often shown to be in competition, for predictions of ozone, particulate matter and other species. Feedbacks were shown to result in local and regional shifts of ozone-forming chemical regime, between NOx- and VOC-limited environments. Feedbacks were shown to have a substantial influence on biogenic hydrocarbon emissions and concentrations: North American simulations incorporating both feedbacks resulted in summer average isoprene concentration decreases of up to 10%, while European direct effect simulations during the Russian forest fire period resulted in grid average isoprene changes of -5 to +12.5%. The atmospheric transport and chemistry of large emitting sources such as plumes from forest fires and large cities were shown to be strongly impacted by the presence or absence of feedback mechanisms in the model simulations. Summertime model performance for ozone and other gases was improved through the inclusion of indirect effect feedbacks, while performance for particulate matter was degraded, suggesting that current parameterizations for in- and below cloud processes, once the cloud locations become more directly influenced by aerosols, may over- or under-predict the strength of these processes. Process parameterization-level comparisons of fully coupled feedback models are therefore recommended for future work, as well as further studies using these models for the simulations of large scale urban/industrial and/or forest fire plumes.

Species-specific effects of soil fauna on fungal foraging and decomposition.

PubMed

Crowther, Thomas W; Boddy, Lynne; Jones, T Hefin

2011-10-01

Decomposer fungi are primary decomposing agents in terrestrial soils. Their mycelial networks play an important role in nutrient mineralisation and distribution, but are also nutritious resources for various soil invertebrates. Global climate change is predicted to alter the diversity and community composition of these soil fauna. To understand whether changes in invertebrate species diversity are likely to affect fungal-mediated decomposition, this study compared the grazing potentials of different invertebrate taxa and functional groups. Specifically, the grazing impacts of seven invertebrate taxa on the growth and spatial distribution of six basidiomycete fungi growing from beech wood blocks in soil microcosms were explored. Wood decay rates by fungi were also compared. The consequences of grazing were both taxon- and species-specific. Generally, macro-invertebrates caused the greatest damage, while meso- and micro-invertebrates often stimulated mycelial growth. Invertebrate size, preferences and population dynamics are likely to influence grazing potentials. Effects of grazing varied between fungi, with mycelial morphology and biochemistry possibly influencing susceptibility. Heavy grazing indirectly increased fungal-mediated wood decomposition. Changes in invertebrate community composition are predicted to have consequences for fungal growth, activity and community structure in woodland soils. Abiotic climate change factors including CO(2) and temperature affect mycelial productivity directly, but the indirect effects, mediated through changes in the soil invertebrate community, may be equally important in controlling ecosystem functioning.

Stigma and the perpetuation of obesity.

PubMed

Brewis, Alexandra A

2014-10-01

Even as obesity rates reach new highs, the social stigmatization of obesity seems to be strengthening and globalizing. This review identifies at least four mechanisms by which a pervasive environment of fat stigma could reinforce high body weights or promote weight gain, ultimately driving population-level obesity. These are direct effects through behavior change because of feeling judged, and indirect effects of social network changes based on stigmatizing actions and decisions by others, psychosocial stress from feeling stigmatized, and the structural effects of discrimination. Importantly, women and children appear especially vulnerable to these mechanisms. The broader model provides an improved basis to investigate the role of stigma in driving the etiology of obesity, and explicates how individual, interpersonal, and structural dimensions of stigma are connected to variation in health outcomes, including across generations. Copyright © 2014 Elsevier Ltd. All rights reserved.

GCM Simulations of the Aerosol Indirect Effect: Sensitivity to Cloud Parameterization and Aerosol Burden

NASA Technical Reports Server (NTRS)

Menon, Surabi; DelGenio, Anthony D.; Koch, Dorothy; Tselioudis, George; Hansen, James E. (Technical Monitor)

2001-01-01

We describe the coupling of the Goddard Institute for Space Studies (GISS) general circulation model (GCM) to an online sulfur chemistry model and source models for organic matter and sea-salt that is used to estimate the aerosol indirect effect. The cloud droplet number concentration is diagnosed empirically from field experiment datasets over land and ocean that observe droplet number and all three aerosol types simultaneously; corrections are made for implied variations in cloud turbulence levels. The resulting cloud droplet number is used to calculate variations in droplet effective radius, which in turn allows us to predict aerosol effects on cloud optical thickness and microphysical process rates. We calculate the aerosol indirect effect by differencing the top-of-the-atmosphere net cloud radiative forcing for simulations with present-day vs. pre-industrial emissions. Both the first (radiative) and second (microphysical) indirect effects are explored. We test the sensitivity of our results to cloud parameterization assumptions that control the vertical distribution of cloud occurrence, the autoconversion rate, and the aerosol scavenging rate, each of which feeds back significantly on the model aerosol burden. The global mean aerosol indirect effect for all three aerosol types ranges from -1.55 to -4.36 W m(exp -2) in our simulations. The results are quite sensitive to the pre-industrial background aerosol burden, with low pre-industrial burdens giving strong indirect effects, and to a lesser extent to the anthropogenic aerosol burden, with large burdens giving somewhat larger indirect effects. Because of this dependence on the background aerosol, model diagnostics such as albedo-particle size correlations and column cloud susceptibility, for which satellite validation products are available, are not good predictors of the resulting indirect effect.

GCM Simulations of the Aerosol Indirect Effect: Sensitivity to Cloud Parameterization and Aerosol Burden

NASA Technical Reports Server (NTRS)

Menon, Surabi; DelGenio, Anthony D.; Koch, Dorothy; Tselioudis, George; Hansen, James E. (Technical Monitor)

2001-01-01

We describe the coupling of the Goddard Institute for Space Studies (GISS) general circulation model (GCM) to an online sulfur chemistry model and source models for organic matter and sea-salt that is used to estimate the aerosol indirect effect. The cloud droplet number concentration is diagnosed empirically from field experiment datasets over land and ocean that observe droplet number and all three aerosol types simultaneously; corrections are made for implied variations in cloud turbulence levels. The resulting cloud droplet number is used to calculate variations in droplet effective radius, which in turn allows us to predict aerosol effects on cloud optical thickness and microphysical process rates. We calculate the aerosol indirect effect by differencing the top-of-the-atmosphere net cloud radiative forcing for simulations with present-day vs. pre-industrial emissions. Both the first (radiative) and second (microphysical) indirect effects are explored. We test the sensitivity of our results to cloud parameterization assumptions that control the vertical distribution of cloud occurrence, the autoconversion rate, and the aerosol scavenging rate, each of which feeds back significantly on the model aerosol burden. The global mean aerosol indirect effect for all three aerosol types ranges from -1.55 to -4.36 W/sq m in our simulations. The results are quite sensitive to the pre-industrial background aerosol burden, with low pre-industrial burdens giving strong indirect effects, and to a lesser extent to the anthropogenic aerosol burden, with large burdens giving somewhat larger indirect effects. Because of this dependence on the background aerosol, model diagnostics such as albedo-particle size correlations and column cloud susceptibility, for which satellite validation products are available, are not good predictors of the resulting indirect effect.

DNA double strand breaks induced by the indirect effect of radiation are more efficiently repaired by non-homologous end joining compared to homologous recombination repair.

PubMed

Bajinskis, Ainars; Natarajan, Adayapalam T; Erixon, Klaus; Harms-Ringdahl, Mats

2013-08-30

The aim of this study was to investigate the relative involvement of three major DNA repair pathways, i.e., non-homologous end joining (NHEJ), homologous recombination (HRR) and base excision (BER) in repair of DNA lesions of different complexity induced by low- or high-LET radiation with emphasis on the contribution of the indirect effect of radiation for these radiation qualities. A panel of DNA repair-deficient CHO cell lines was irradiated by (137)Cs γ-rays or radon progeny α-particles. Irradiation was also performed in the presence of 2M DMSO to reduce the indirect effect of radiation and the complexity of the DNA damage formed. Clonogenic survival and micronucleus assays were used to estimate efficiencies of the different repair pathways for DNA damages produced by direct and indirect effects. Removal of the indirect effect of low-LET radiation by DMSO increased clonogenic survival and decreased MN formation for all cell lines investigated. A direct contribution of the indirect effect of radiation to DNA base damage was suggested by the significant protection by DMSO seen for the BER deficient cell line. Lesions formed by the indirect effect are more readily repaired by the NHEJ pathway than by HRR after irradiation with γ-rays or α-particles as evaluated by cell survival and the yields of MN. The results obtained with BER- and NHEJ-deficient cells suggest that the indirect effect of radiation contributes significantly to the formation of repair substrates for these pathways. Copyright © 2013 Elsevier B.V. All rights reserved.

INDIRECT EFFECT OF X-RADIATION ON BONE GROWTH IN RATS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conard, R.A.

1962-12-21

Effects of 200 to 600 r of x irradiation on tibial bone growth in groups of weanling male rats were studied by in vivo measurement of tibial bone growth in serial radiographs. By comparison of growth rates in shielded with unshielded legs, direct and indirect effects of radiation were demonstrated, both roughly dose dependent, but with the indirect effect being about twice that of the direct effect. Pair-feeding experiments showed that about 70% of the indirect effect was due to radiation-induced lowered food consumption. By partial-body shielding experiments, using pnir-fed controls, it was shown that the abdomen may be themore » site of a non-nutritional abscopal effect. (auth)« less

SPSS and SAS procedures for estimating indirect effects in simple mediation models.

PubMed

Preacher, Kristopher J; Hayes, Andrew F

2004-11-01

Researchers often conduct mediation analysis in order to indirectly assess the effect of a proposed cause on some outcome through a proposed mediator. The utility of mediation analysis stems from its ability to go beyond the merely descriptive to a more functional understanding of the relationships among variables. A necessary component of mediation is a statistically and practically significant indirect effect. Although mediation hypotheses are frequently explored in psychological research, formal significance tests of indirect effects are rarely conducted. After a brief overview of mediation, we argue the importance of directly testing the significance of indirect effects and provide SPSS and SAS macros that facilitate estimation of the indirect effect with a normal theory approach and a bootstrap approach to obtaining confidence intervals, as well as the traditional approach advocated by Baron and Kenny (1986). We hope that this discussion and the macros will enhance the frequency of formal mediation tests in the psychology literature. Electronic copies of these macros may be downloaded from the Psychonomic Society's Web archive at www.psychonomic.org/archive/.

The indirect effects of cheatgrass invasion: Grasshopper herbivory on native grasses determined by neighboring cheatgrass abundance

Treesearch

Julie Beckstead; Susan E. Meyer; Carol K. Augsperger

2008-01-01

Invasion biology has focused on the direct effects of plant invasion and has generally overlooked indirect interactions. Here we link theories of invasion biology and herbivory to explore an indirect effect of one invading species on associational herbivory (the effect of neighboring plants on herbivory) of native species. We studied a Great Basin shadscale (...

An overview of natural hazard impacts to railways and urban transportation systems

NASA Astrophysics Data System (ADS)

Bíl, Michal; Nezval, Vojtěch; Bílová, Martina; Andrášik, Richard; Kubeček, Jan

2017-04-01

We present an overview and two case studies of natural hazard impacts on rail transportation systems in the Czech Republic. Flooding, landsliding, heavy snowfall, windstorms and glaze (black ice) are the most common natural processes which occur in this region. Whereas flooding and landsliding usually cause direct damage to the transportation infrastructure, other hazards predominantly cause indirect losses. Railway and urban tramline networks are almost fully dependent on electricity which is provided by a system of overhead lines (electric lines above the tracks). These lines are extremely susceptible to formation of glaze which blocks conduction of electric current. A December 2014 glaze event caused significant indirect losses in the largest Czech cities and railways due to the above-mentioned process. Details of this event will be provided during the presentation. Windstorms usually cause tree falls which can affect overhead lines and physically block railway tracks. Approximately 30 % of the Czech railway network is closer than 50 m from the nearest forest. This presents significant potential for transport interruption due to falling trees. Complicated legal relations among the owners of the plots of land along railways, the environment (full-grown trees and related habitat), and the railway administrator are behind many traffic interruptions due to falling trees. We have registered 2040 tree falls between 2012 and 2015 on the railway network. A model of the fallen tree hazard was created for the entire Czech railway network. Both above-mentioned case studies provide illustrative examples of the increased fragility of the modern transportation systems which fully rely on electricity. Natural processes with a low destructive power are thereby able to cause network wide service cut-offs.

Structure and effect of sarcosine on water and urea by using molecular dynamics simulations: Implications in protein stabilization.

PubMed

Kumar, Narendra; Kishore, Nand

2013-01-01

Sarcosine is one of the most important protecting osmolytes which is also known to counteract the denaturing effect of urea. We used molecular dynamics simulation methods to investigate the mechanism of protein stabilization and counteraction of urea by sarcosine. We found that sarcosine enhanced the tetrahedral structure of water and strengthened its hydrogen bonding network. We also found that sarcosine did not form clusters unlike glycine. Our results show strong interaction between sarcosine and urea molecules. Addition of sarcosine enhanced the urea-water structure and urea-water lifetime indicated an increase in the solvation of urea. These findings suggest that sarcosine indirectly stabilizes protein by enhancing water-water structure thus decreasing the hydrophobic effect and counteracts the effect of urea by increasing the solvation of urea and directly interacting with it leaving urea less available to interact with protein. Copyright © 2012 Elsevier B.V. All rights reserved.

Lonely people are no longer lonely on social networking sites: the mediating role of self-disclosure and social support.

PubMed

Lee, Kyung-Tag; Noh, Mi-Jin; Koo, Dong-Mo

2013-06-01

Most previous studies assert the negative effect of loneliness on social life and an individual's well-being when individuals use the Internet. To expand this previous research tradition, the current study proposes a model to test whether loneliness has a direct or indirect effect on well-being when mediated by self-disclosure and social support. The results show that loneliness has a direct negative impact on well-being but a positive effect on self-disclosure. While self-disclosure positively influences social support, self-disclosure has no impact on well-being, and social support positively influences well-being. The results also show a full mediation effect of social support in the self-disclosure to well-being link. The results imply that even if lonely people's well-being is poor, their well-being can be enhanced through the use of SNSs, including self-presentation and social support from their friends.

Measuring distance through dense weighted networks: The case of hospital-associated pathogens

PubMed Central

Smieszek, Timo; Henderson, Katherine L.; Johnson, Alan P.

2017-01-01

Hospital networks, formed by patients visiting multiple hospitals, affect the spread of hospital-associated infections, resulting in differences in risks for hospitals depending on their network position. These networks are increasingly used to inform strategies to prevent and control the spread of hospital-associated pathogens. However, many studies only consider patients that are received directly from the initial hospital, without considering the effect of indirect trajectories through the network. We determine the optimal way to measure the distance between hospitals within the network, by reconstructing the English hospital network based on shared patients in 2014–2015, and simulating the spread of a hospital-associated pathogen between hospitals, taking into consideration that each intermediate hospital conveys a delay in the further spread of the pathogen. While the risk of transferring a hospital-associated pathogen between directly neighbouring hospitals is a direct reflection of the number of shared patients, the distance between two hospitals far-away in the network is determined largely by the number of intermediate hospitals in the network. Because the network is dense, most long distance transmission chains in fact involve only few intermediate steps, spreading along the many weak links. The dense connectivity of hospital networks, together with a strong regional structure, causes hospital-associated pathogens to spread from the initial outbreak in a two-step process: first, the directly surrounding hospitals are affected through the strong connections, second all other hospitals receive introductions through the multitude of weaker links. Although the strong connections matter for local spread, weak links in the network can offer ideal routes for hospital-associated pathogens to travel further faster. This hold important implications for infection prevention and control efforts: if a local outbreak is not controlled in time, colonised patients will appear in other regions, irrespective of the distance to the initial outbreak, making import screening ever more difficult. PMID:28771581

Direct effects dominate responses to climate perturbations in grassland plant communities.

PubMed

Chu, Chengjin; Kleinhesselink, Andrew R; Havstad, Kris M; McClaran, Mitchel P; Peters, Debra P; Vermeire, Lance T; Wei, Haiyan; Adler, Peter B

2016-06-08

Theory predicts that strong indirect effects of environmental change will impact communities when niche differences between competitors are small and variation in the direct effects experienced by competitors is large, but empirical tests are lacking. Here we estimate negative frequency dependence, a proxy for niche differences, and quantify the direct and indirect effects of climate change on each species. Consistent with theory, in four of five communities indirect effects are strongest for species showing weak negative frequency dependence. Indirect effects are also stronger in communities where there is greater variation in direct effects. Overall responses to climate perturbations are driven primarily by direct effects, suggesting that single species models may be adequate for forecasting the impacts of climate change in these communities.

The peer effect on pain tolerance.

PubMed

Engebretsen, Solveig; Frigessi, Arnoldo; Engø-Monsen, Kenth; Furberg, Anne-Sofie; Stubhaug, Audun; de Blasio, Birgitte Freiesleben; Nielsen, Christopher Sivert

2018-05-19

Twin studies have found that approximately half of the variance in pain tolerance can be explained by genetic factors, while shared family environment has a negligible effect. Hence, a large proportion of the variance in pain tolerance is explained by the (non-shared) unique environment. The social environment beyond the family is a potential candidate for explaining some of the variance in pain tolerance. Numerous individual traits have previously shown to be associated with friendship ties. In this study, we investigate whether pain tolerance is associated with friendship ties. We study the friendship effect on pain tolerance by considering data from the Tromsø Study: Fit Futures I, which contains pain tolerance measurements and social network information for adolescents attending first year of upper secondary school in the Tromsø area in Northern Norway. Pain tolerance was measured with the cold-pressor test (primary outcome), contact heat and pressure algometry. We analyse the data by using statistical methods from social network analysis. Specifically, we compute pairwise correlations in pain tolerance among friends. We also fit network autocorrelation models to the data, where the pain tolerance of an individual is explained by (among other factors) the average pain tolerance of the individual's friends. We find a significant and positive relationship between the pain tolerance of an individual and the pain tolerance of their friends. The estimated effect is that for every 1 s increase in friends' average cold-pressor tolerance time, the expected cold-pressor pain tolerance of the individual increases by 0.21 s (p-value: 0.0049, sample size n=997). This estimated effect is controlled for sex. The friendship effect remains significant when controlling for potential confounders such as lifestyle factors and test sequence among the students. Further investigating the role of sex on this friendship effect, we only find a significant peer effect of male friends on males, while there is no significant effect of friends' average pain tolerance on females in stratified analyses. Similar, but somewhat lower estimates were obtained for the other pain modalities. We find a positive and significant peer effect in pain tolerance. Hence, there is a significant tendency for students to be friends with others with similar pain tolerance. Sex-stratified analyses show that the only significant effect is the effect of male friends on males. Two different processes can explain the friendship effect in pain tolerance, selection and social transmission. Individuals might select friends directly due to similarity in pain tolerance, or indirectly through similarity in other confounding variables that affect pain tolerance. Alternatively, there is an influence effect among friends either directly in pain tolerance, or indirectly through other variables that affect pain tolerance. If there is indeed a social influence effect in pain tolerance, then the social environment can account for some of the unique environmental variance in pain tolerance. If so, it is possible to therapeutically affect pain tolerance through alteration of the social environment.

Estimation of indirect effect when the mediator is a censored variable.

PubMed

Wang, Jian; Shete, Sanjay

2017-01-01

A mediation model explores the direct and indirect effects of an initial variable ( X) on an outcome variable ( Y) by including a mediator ( M). In many realistic scenarios, investigators observe censored data instead of the complete data. Current research in mediation analysis for censored data focuses mainly on censored outcomes, but not censored mediators. In this study, we proposed a strategy based on the accelerated failure time model and a multiple imputation approach. We adapted a measure of the indirect effect for the mediation model with a censored mediator, which can assess the indirect effect at both the group and individual levels. Based on simulation, we established the bias in the estimations of different paths (i.e. the effects of X on M [ a], of M on Y [ b] and of X on Y given mediator M [ c']) and indirect effects when analyzing the data using the existing approaches, including a naïve approach implemented in software such as Mplus, complete-case analysis, and the Tobit mediation model. We conducted simulation studies to investigate the performance of the proposed strategy compared to that of the existing approaches. The proposed strategy accurately estimates the coefficients of different paths, indirect effects and percentages of the total effects mediated. We applied these mediation approaches to the study of SNPs, age at menopause and fasting glucose levels. Our results indicate that there is no indirect effect of association between SNPs and fasting glucose level that is mediated through the age at menopause.

The protective effects of parental monitoring and internet restriction on adolescents' risk of online harassment.

PubMed

Khurana, Atika; Bleakley, Amy; Jordan, Amy B; Romer, Daniel

2015-05-01

With many adolescents using the internet to communicate with their peers, online harassment is on the rise among youth. The purpose of this study was to understand how parental monitoring and strategies parents use to regulate children's internet use (i.e., internet restriction) can help reduce online harassment among adolescents. Online survey data were collected from a nationally representative sample of parents and their 12-17 year old adolescents (n = 629; 49 % female). Structural equation modeling was used to test direct and indirect effects of parental monitoring and internet restriction on being a victim of online harassment. Potential mediators included adolescents' frequency of use of social networking websites, time spent on computers outside of school, and internet access in the adolescent's bedroom. Age and gender differences were also explored. Adolescents' reports of parental monitoring and efforts to regulate specific forms of internet use were associated with reduced rates of online harassment. Specifically, the effect of parental monitoring was largely direct and 26 times greater than parental internet restriction. The latter was associated with lower rates of harassment only indirectly by limiting internet access in the adolescent's bedroom. These effects operated similarly for younger and older adolescents and for males and females. Adolescents' perceptions of parental monitoring and awareness can be protective against online harassment. Specific restriction strategies such as regulating internet time and content can also help reduce the risk of online harassment.

Cortical functional hyperconnectivity in a mouse model of depression and selective network effects of ketamine.

PubMed

McGirr, Alexander; LeDue, Jeffrey; Chan, Allen W; Xie, Yicheng; Murphy, Timothy H

2017-08-01

See Huang and Liston (doi:10.1093/awx166) for a scientific commentary on this article.Human depression is associated with glutamatergic dysfunction and alterations in resting state network activity. However, the indirect nature of human in vivo glutamate and activity assessments obscures mechanistic details. Using the chronic social defeat mouse model of depression, we determine how mesoscale glutamatergic networks are altered after chronic stress, and in response to the rapid acting antidepressant, ketamine. Transgenic mice (Ai85) expressing iGluSnFR (a recombinant protein sensor) permitted real-time in vivo selective characterization of extracellular glutamate and longitudinal imaging of mesoscale cortical glutamatergic functional circuits. Mice underwent chronic social defeat or a control condition, while spontaneous cortical activity was longitudinally sampled. After chronic social defeat, we observed network-wide glutamate functional hyperconnectivity in defeated animals, which was confirmed with voltage sensitive dye imaging in an independent cohort. Subanaesthetic ketamine has unique effects in defeated animals. Acutely, subanaesthetic ketamine induces large global cortical glutamate transients in defeated animals, and an elevated subanaesthetic dose resulted in sustained global increase in cortical glutamate. Local cortical inhibition of glutamate transporters in naïve mice given ketamine produced a similar extracellular glutamate phenotype, with both glutamate transients and a dose-dependent accumulation of glutamate. Twenty-four hours after ketamine, normalization of depressive-like behaviour in defeated animals was accompanied by reduced glutamate functional connectivity strength. Altered glutamate functional connectivity in this animal model confirms the central role of glutamate dynamics as well as network-wide changes after chronic stress and in response to ketamine. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Adaptive evolution of body size subject to indirect effect in trophic cascade system.

PubMed

Wang, Xin; Fan, Meng; Hao, Lina

2017-09-01

Trophic cascades represent a classic example of indirect effect and are wide-spread in nature. Their ecological impact are well established, but the evolutionary consequences have received even less theoretical attention. We theoretically and numerically investigate the trait (i.e., body size of consumer) evolution in response to indirect effect in a trophic cascade system. By applying the quantitative trait evolutionary theory and the adaptive dynamic theory, we formulate and explore two different types of eco-evolutionary resource-consumer-predator trophic cascade model. First, an eco-evolutionary model incorporating the rapid evolution is formulated to investigate the effect of rapid evolution of the consumer's body size, and to explore the impact of density-mediate indirect effect on the population dynamics and trait dynamics. Next, by employing the adaptive dynamic theory, a long-term evolutionary model of consumer body size is formulated to evaluate the effect of long-term evolution on the population dynamics and the effect of trait-mediate indirect effect. Those models admit rich dynamics that has not been observed yet in empirical studies. It is found that, both in the trait-mediated and density-mediated system, the body size of consumer in predator-consumer-resource interaction (indirect effect) evolves smaller than that in consumer-resource and predator-consumer interaction (direct effect). Moreover, in the density-mediated system, we found that the evolution of consumer body size contributes to avoiding consumer extinction (i.e., evolutionary rescue). The trait-mediate and density-mediate effects may produce opposite evolutionary response. This study suggests that the trophic cascade indirect effect affects consumer evolution, highlights a more comprehensive mechanistic understanding of the intricate interplay between ecological and evolutionary force. The modeling approaches provide avenue for study on indirect effects from an evolutionary perspective. Copyright © 2017 Elsevier B.V. All rights reserved.

Quantifying and Testing Indirect Effects in Simple Mediation Models when the Constituent Paths Are Nonlinear

ERIC Educational Resources Information Center

Hayes, Andrew F.; Preacher, Kristopher J.

2010-01-01

Most treatments of indirect effects and mediation in the statistical methods literature and the corresponding methods used by behavioral scientists have assumed linear relationships between variables in the causal system. Here we describe and extend a method first introduced by Stolzenberg (1980) for estimating indirect effects in models of…

Exercise and BMI z-score in overweight and obese children and adolescents: protocol for a systematic review and network meta-analysis of randomised trials.

PubMed

Kelley, George A; Kelley, Kristi S

2016-04-15

While overweight and obesity in children and adolescents is a major global health problem, the effects of exercise on overweight and obesity in children and adolescents are not well established despite numerous studies on this topic. The purpose of this study is to use the network meta-analytic approach to determine the effects of exercise (aerobic, strength training or both) on body mass index (BMI) z-score in overweight and obese children and adolescents. Randomised exercise intervention trials >4 weeks, published in any language between 1 January 1990 and 31 September 2015, and which include direct and/or indirect evidence, will be included. Studies will be retrieved by searching 6 electronic databases, cross-referencing and expert review. Dual abstraction of data will occur. The primary outcome will be changes in BMI z-score while the secondary outcome will be changes in body weight in kilograms (kg). Risk of bias will be assessed using the Cochrane risk of bias assessment instrument while confidence in the cumulative evidence will be assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) instrument for network meta-analysis. Network meta-analysis will be performed using multivariate random-effects meta-regression models. The surface under the cumulative ranking curve will be used to provide a hierarchy of exercise treatments (aerobic, strength training or both). The results of this study will be presented at a professional conference and published in a peer-reviewed journal. CRD42015026377. 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/

Protozoan Bacterivory and Escherichia coli Survival in Drinking Water Distribution Systems

PubMed Central

Sibille, I.; Sime-Ngando, T.; Mathieu, L.; Block, J. C.

1998-01-01

The development of bacterial communities in drinking water distribution systems leads to a food chain which supports the growth of macroorganisms incompatible with water quality requirements and esthetics. Nevertheless, very few studies have examined the microbial communities in drinking water distribution systems and their trophic relationships. This study was done to quantify the microbial communities (especially bacteria and protozoa) and obtain direct and indirect proof of protozoan feeding on bacteria in two distribution networks, one of GAC water (i.e., water filtered on granular activated carbon) and the other of nanofiltered water. The nanofiltered water-supplied network contained no organisms larger than bacteria, either in the water phase (on average, 5 × 107 bacterial cells liter−1) or in the biofilm (on average, 7 × 106 bacterial cells cm−2). No protozoa were detected in the whole nanofiltered water-supplied network (water plus biofilm). In contrast, the GAC water-supplied network contained bacteria (on average, 3 × 108 cells liter−1 in water and 4 × 107 cells cm−2 in biofilm) and protozoa (on average, 105 cells liter−1 in water and 103 cells cm−2 in biofilm). The water contained mostly flagellates (93%), ciliates (1.8%), thecamoebae (1.6%), and naked amoebae (1.1%). The biofilm had only ciliates (52%) and thecamoebae (48%). Only the ciliates at the solid-liquid interface of the GAC water-supplied network had a measurable grazing activity in laboratory test (estimated at 2 bacteria per ciliate per h). Protozoan ingestion of bacteria was indirectly shown by adding Escherichia coli to the experimental distribution systems. Unexpectedly, E. coli was lost from the GAC water-supplied network more rapidly than from the nanofiltered water-supplied network, perhaps because of the grazing activity of protozoa in GAC water but not in nanofiltered water. Thus, the GAC water-supplied network contained a functional ecosystem with well-established and structured microbial communities, while the nanofiltered water-supplied system did not. The presence of protozoa in drinking water distribution systems must not be neglected because these populations may regulate the autochthonous and allochthonous bacterial populations. PMID:9435076

Protozoan bacterivory and Escherichia coli survival in drinking water distribution systems.

PubMed

Sibille, I; Sime-Ngando, T; Mathieu, L; Block, J C

1998-01-01

The development of bacterial communities in drinking water distribution systems leads to a food chain which supports the growth of macroorganisms incompatible with water quality requirements and esthetics. Nevertheless, very few studies have examined the microbial communities in drinking water distribution systems and their trophic relationships. This study was done to quantify the microbial communities (especially bacteria and protozoa) and obtain direct and indirect proof of protozoan feeding on bacteria in two distribution networks, one of GAC water (i.e., water filtered on granular activated carbon) and the other of nanofiltered water. The nanofiltered water-supplied network contained no organisms larger than bacteria, either in the water phase (on average, 5 x 10(7) bacterial cells liter-1) or in the biofilm (on average, 7 x 10(6) bacterial cells cm-2). No protozoa were detected in the whole nanofiltered water-supplied network (water plus biofilm). In contrast, the GAC water-supplied network contained bacteria (on average, 3 x 10(8) cells liter-1 in water and 4 x 10(7) cells cm-2 in biofilm) and protozoa (on average, 10(5) cells liter-1 in water and 10(3) cells cm-2 in biofilm). The water contained mostly flagellates (93%), ciliates (1.8%), thecamoebae (1.6%), and naked amoebae (1.1%). The biofilm had only ciliates (52%) and thecamoebae (48%). Only the ciliates at the solid-liquid interface of the GAC water-supplied network had a measurable grazing activity in laboratory test (estimated at 2 bacteria per ciliate per h). Protozoan ingestion of bacteria was indirectly shown by adding Escherichia coli to the experimental distribution systems. Unexpectedly, E. coli was lost from the GAC water-supplied network more rapidly than from the nanofiltered water-supplied network, perhaps because of the grazing activity of protozoa in GAC water but not in nanofiltered water. Thus, the GAC water-supplied network contained a functional ecosystem with well-established and structured microbial communities, while the nanofiltered water-supplied system did not. The presence of protozoa in drinking water distribution systems must not be neglected because these populations may regulate the autochthonous and allochthonous bacterial populations.

The relationship between physical and mental health: A mediation analysis.

PubMed

Ohrnberger, Julius; Fichera, Eleonora; Sutton, Matt

2017-12-01

There is a strong link between mental health and physical health, but little is known about the pathways from one to the other. We analyse the direct and indirect effects of past mental health on present physical health and past physical health on present mental health using lifestyle choices and social capital in a mediation framework. We use data on 10,693 individuals aged 50 years and over from six waves (2002-2012) of the English Longitudinal Study of Ageing. Mental health is measured by the Centre for Epidemiological Studies Depression Scale (CES) and physical health by the Activities of Daily Living (ADL). We find significant direct and indirect effects for both forms of health, with indirect effects explaining 10% of the effect of past mental health on physical health and 8% of the effect of past physical health on mental health. Physical activity is the largest contributor to the indirect effects. There are stronger indirect effects for males in mental health (9.9%) and for older age groups in mental health (13.6%) and in physical health (12.6%). Health policies aiming at changing physical and mental health need to consider not only the direct cross-effects but also the indirect cross-effects between mental health and physical health. Copyright © 2017. Published by Elsevier Ltd.

Direct and Indirect Influence of Non-Native Neighbours on Pollination and Fruit Production of a Native Plant.

PubMed

Montero-Castaño, Ana; Vilà, Montserrat

2015-01-01

Entomophilous non-native plants can directly affect the pollination and reproductive success of native plant species and also indirectly, by altering the composition and abundance of floral resources in the invaded community. Separating direct from indirect effects is critical for understanding the mechanisms underlying the impacts of non-native species on recipient communities. Our aims are: (a) to explore both the direct effect of the non-native Hedysarum coronarium and its indirect effect, mediated by the alteration of floral diversity, on the pollinator visitation rate and fructification of the native Leopoldia comosa and (b) to distinguish whether the effects of the non-native species were due to its floral display or to its vegetative interactions. We conducted field observations within a flower removal experimental setup (i.e. non-native species present, absent and with its inflorescences removed) at the neighbourhood scale. Our study illustrates the complexity of mechanisms involved in the impacts of non-native species on native species. Overall, Hedysarum increased pollinator visitation rates to Leopoldia target plants as a result of direct and indirect effects acting in the same direction. Due to its floral display, Hedysarum exerted a direct magnet effect attracting visits to native target plants, especially those made by the honeybee. Indirectly, Hedysarum also increased the visitation rate of native target plants. Due to the competition for resources mediated by its vegetative parts, it decreased floral diversity in the neighbourhoods, which was negatively related to the visitation rate to native target plants. Hedysarum overall also increased the fructification of Leopoldia target plants, even though such an increase was the result of other indirect effects compensating for the observed negative indirect effect mediated by the decrease of floral diversity.

Direct and Indirect Influence of Non-Native Neighbours on Pollination and Fruit Production of a Native Plant

PubMed Central

Montero-Castaño, Ana; Vilà, Montserrat

2015-01-01

Background Entomophilous non-native plants can directly affect the pollination and reproductive success of native plant species and also indirectly, by altering the composition and abundance of floral resources in the invaded community. Separating direct from indirect effects is critical for understanding the mechanisms underlying the impacts of non-native species on recipient communities. Objectives Our aims are: (a) to explore both the direct effect of the non-native Hedysarum coronarium and its indirect effect, mediated by the alteration of floral diversity, on the pollinator visitation rate and fructification of the native Leopoldia comosa and (b) to distinguish whether the effects of the non-native species were due to its floral display or to its vegetative interactions. Methods We conducted field observations within a flower removal experimental setup (i.e. non-native species present, absent and with its inflorescences removed) at the neighbourhood scale. Results Our study illustrates the complexity of mechanisms involved in the impacts of non-native species on native species. Overall, Hedysarum increased pollinator visitation rates to Leopoldia target plants as a result of direct and indirect effects acting in the same direction. Due to its floral display, Hedysarum exerted a direct magnet effect attracting visits to native target plants, especially those made by the honeybee. Indirectly, Hedysarum also increased the visitation rate of native target plants. Due to the competition for resources mediated by its vegetative parts, it decreased floral diversity in the neighbourhoods, which was negatively related to the visitation rate to native target plants. Hedysarum overall also increased the fructification of Leopoldia target plants, even though such an increase was the result of other indirect effects compensating for the observed negative indirect effect mediated by the decrease of floral diversity. PMID:26110630

The role of sex of peers and gender-typed activities in young children's peer affiliative networks: a longitudinal analysis of selection and influence.

PubMed

Martin, Carol Lynn; Kornienko, Olga; Schaefer, David R; Hanish, Laura D; Fabes, Richard A; Goble, Priscilla

2013-01-01

A stochastic actor-based model was used to investigate the origins of sex segregation by examining how similarity in sex of peers and time spent in gender-typed activities affected affiliation network selection and how peers influenced children's (N = 292; Mage = 4.3 years) activity involvement. Gender had powerful effects on interactions through direct and indirect pathways. Children selected playmates of the same sex and with similar levels of gender-typed activities. Selection based on gender-typed activities partially mediated selection based on sex of peers. Children influenced one another's engagement in gender-typed activities. When mechanisms producing sex segregation were compared, the largest contributor was selection based on sex of peers; less was due to activity-based selection and peer influence. Implications for sex segregation and gender development are discussed. © 2012 The Authors. Child Development © 2012 Society for Research in Child Development, Inc.

Peer Contexts in Schools: Avenues Toward Behavioral Health in Early Adolescence.

PubMed

Cappella, Elise; Hwang, Sophia H J

2015-01-01

Peer contexts play an important role in the behavioral health of early adolescents in schools. Behavioral health involves the observable academic and social behaviors that relate to and influence youths' subsequent health and development. Setting-level research on peer networks and social norms indicates these aspects of peer contexts vary by peer group, classroom, and school and dynamically relate to individual students' academic and social behaviors. Yet, although peer contexts are both influential and potentially malleable, little research examines the effects of school and classroom interventions on the development and maintenance of positive and productive peer contexts in schools. The current article identifies school structures and classroom processes theorized to directly or indirectly shift peer networks and social norms-and thereby increase the behavioral health of early adolescents in schools. We discuss the need for more rigorous and relevant research to better understand the role of schools and classrooms in strengthening these peer contexts and promoting behavioral health in early adolescence.

The Embeddedness of Adolescent Friendship Nominations: The Formation of Social Capital in Emergent Network Structures

PubMed Central

Frank, Kenneth A.; Muller, Chandra; Mueller, Anna S.

2014-01-01

Although research on social embeddedness and social capital con-firms the value of friendship networks, little has been written about how social relations form and are structured by social institutions. Using data from the Adolescent Health and Academic Achievement study and the National Longitudinal Study of Adolescent Health, the authors show that the odds of a new friendship nomination were 1.77 times greater within clusters of high school students taking courses together than between them. The estimated effect cannot be attributed to exposure to peers in similar grade levels, indirect friendship links, or pair-level course overlap, and the finding is robust to alternative model specifications. The authors also show how tendencies associated with status hierarchy inhering in triadic friendship nominations are neutralized within the clusters. These results have implications for the production and distribution of social capital within social systems such as schools, giving the clusters social salience as “local positions.” PMID:25364011

Using Neural Networks to Improve the Performance of Radiative Transfer Modeling Used for Geometry Dependent Surface Lambertian-Equivalent Reflectivity Calculations

NASA Technical Reports Server (NTRS)

Fasnacht, Zachary; Qin, Wenhan; Haffner, David P.; Loyola, Diego; Joiner, Joanna; Krotkov, Nickolay; Vasilkov, Alexander; Spurr, Robert

2017-01-01

Surface Lambertian-equivalent reflectivity (LER) is important for trace gas retrievals in the direct calculation of cloud fractions and indirect calculation of the air mass factor. Current trace gas retrievals use climatological surface LER's. Surface properties that impact the bidirectional reflectance distribution function (BRDF) as well as varying satellite viewing geometry can be important for retrieval of trace gases. Geometry Dependent LER (GLER) captures these effects with its calculation of sun normalized radiances (I/F) and can be used in current LER algorithms (Vasilkov et al. 2016). Pixel by pixel radiative transfer calculations are computationally expensive for large datasets. Modern satellite missions such as the Tropospheric Monitoring Instrument (TROPOMI) produce very large datasets as they take measurements at much higher spatial and spectral resolutions. Look up table (LUT) interpolation improves the speed of radiative transfer calculations but complexity increases for non-linear functions. Neural networks perform fast calculations and can accurately predict both non-linear and linear functions with little effort.

Inferring functional connectivity in MRI using Bayesian network structure learning with a modified PC algorithm

PubMed Central

Iyer, Swathi; Shafran, Izhak; Grayson, David; Gates, Kathleen; Nigg, Joel; Fair, Damien

2013-01-01

Resting state functional connectivity MRI (rs-fcMRI) is a popular technique used to gauge the functional relatedness between regions in the brain for typical and special populations. Most of the work to date determines this relationship by using Pearson's correlation on BOLD fMRI timeseries. However, it has been recognized that there are at least two key limitations to this method. First, it is not possible to resolve the direct and indirect connections/influences. Second, the direction of information flow between the regions cannot be differentiated. In the current paper, we follow-up on recent work by Smith et al (2011), and apply a Bayesian approach called the PC algorithm to both simulated data and empirical data to determine whether these two factors can be discerned with group average, as opposed to single subject, functional connectivity data. When applied on simulated individual subjects, the algorithm performs well determining indirect and direct connection but fails in determining directionality. However, when applied at group level, PC algorithm gives strong results for both indirect and direct connections and the direction of information flow. Applying the algorithm on empirical data, using a diffusion-weighted imaging (DWI) structural connectivity matrix as the baseline, the PC algorithm outperformed the direct correlations. We conclude that, under certain conditions, the PC algorithm leads to an improved estimate of brain network structure compared to the traditional connectivity analysis based on correlations. PMID:23501054

Microarray expression profiling and co-expression network analysis of circulating LncRNAs and mRNAs associated with neurotoxicity induced by BPA.

PubMed

Pang, Wei; Lian, Fu-Zhi; Leng, Xue; Wang, Shu-Min; Li, Yi-Bo; Wang, Zi-Yu; Li, Kai-Ren; Gao, Zhi-Xian; Jiang, Yu-Gang

2018-05-01

A growing body of evidence has shown bisphenol A (BPA), an estrogen-like industrial chemical, has adverse effects on the nervous system. In this study, we investigated the transcriptional behavior of long non-coding RNAs (lncRNAs) and mRNAs to provide the information to explore neurotoxic effects induced by BPA. By microarray expression profiling, we discovered 151 differentially expressed lncRNAs and 794 differentially expressed mRNAs in the BPA intervention group compared with the control group. Gene ontology analysis indicated the differentially expressed mRNAs were mainly involved in fundamental metabolic processes and physiological and pathological conditions, such as development, synaptic transmission, homeostasis, injury, and neuroinflammation responses. In the expression network of the BPA-induced group, a great number of nodes and connections were found in comparison to the control-derived network. We identified lncRNAs that were aberrantly expressed in the BPA group, among which, growth arrest specific 5 (GAS5) might participate in the BPA-induced neurotoxicity by regulating Jun, RAS, and other pathways indirectly through these differentially expressed genes. This study provides the first investigation of genome-wide lncRNA expression and correlation between lncRNA and mRNA expression in the BPA-induced neurotoxicity. Our results suggest that the elevated expression of lncRNAs is a major biomarker in the neurotoxicity induced by BPA.

Visual sensory networks and effective information transfer in animal groups.

PubMed

Strandburg-Peshkin, Ariana; Twomey, Colin R; Bode, Nikolai W F; Kao, Albert B; Katz, Yael; Ioannou, Christos C; Rosenthal, Sara B; Torney, Colin J; Wu, Hai Shan; Levin, Simon A; Couzin, Iain D

2013-09-09

Social transmission of information is vital for many group-living animals, allowing coordination of motion and effective response to complex environments. Revealing the interaction networks underlying information flow within these groups is a central challenge. Previous work has modeled interactions between individuals based directly on their relative spatial positions: each individual is considered to interact with all neighbors within a fixed distance (metric range), a fixed number of nearest neighbors (topological range), a 'shell' of near neighbors (Voronoi range), or some combination (Figure 1A). However, conclusive evidence to support these assumptions is lacking. Here, we employ a novel approach that considers individual movement decisions to be based explicitly on the sensory information available to the organism. In other words, we consider that while spatial relations do inform interactions between individuals, they do so indirectly, through individuals' detection of sensory cues. We reconstruct computationally the visual field of each individual throughout experiments designed to investigate information propagation within fish schools (golden shiners, Notemigonus crysoleucas). Explicitly considering visual sensing allows us to more accurately predict the propagation of behavioral change in these groups during leadership events. Furthermore, we find that structural properties of visual interaction networks differ markedly from those of metric and topological counterparts, suggesting that previous assumptions may not appropriately reflect information flow in animal groups. Copyright © 2013 Elsevier Ltd. All rights reserved.

Calcium and Vitamin D Supplementation for Prevention of Preeclampsia: A Systematic Review and Network Meta-Analysis

PubMed Central

Khaing, Win; Vallibhakara, Sakda Arj-Ong; Tantrakul, Visasiri; Vallibhakara, Orawin; Rattanasiri, Sasivimol; McEvoy, Mark; Attia, John; Thakkinstian, Ammarin

2017-01-01

Vitamin D supplementation effects with or without calcium in pregnancy for reducing risk of preeclampsia and gestational or pregnancy induced hypertension are controversial. Literature was systematically searched in Medline, Scopus and Cochrane databases from inception to July 2017. Only randomized controlled trials (RCTs) in English were selected if they had any pair of interventions (calcium, vitamin D, both, or placebo). Systematic review with two-step network-meta-analysis was used to indirectly estimate supplementary effects. Twenty-seven RCTs with 28,000 women were eligible. A direct meta-analysis suggested that calcium, vitamin D, and calcium plus vitamin D could lower risk of preeclampsia when compared to placebo with the pooled risk ratios (RRs) of 0.54 (0.41, 0.70), 0.47 (0.24, 0.89) and 0.50 (0.32, 0.78), respectively. Results of network meta-analysis were similar with the corresponding RRs of 0.49 (0.35, 0.69), 0.43 (0.17, 1.11), and 0.57 (0.30, 1.10), respectively. None of the controls were significant. Efficacy of supplementation, which was ranked by surface under cumulative ranking probabilities, were: vitamin D (47.4%), calcium (31.6%) and calcium plus vitamin D (19.6%), respectively. Calcium supplementation may be used for prevention for preeclampsia. Vitamin D might also worked well but further large scale RCTs are warranted to confirm our findings. PMID:29057843

Calcium and Vitamin D Supplementation for Prevention of Preeclampsia: A Systematic Review and Network Meta-Analysis.

PubMed

Khaing, Win; Vallibhakara, Sakda Arj-Ong; Tantrakul, Visasiri; Vallibhakara, Orawin; Rattanasiri, Sasivimol; McEvoy, Mark; Attia, John; Thakkinstian, Ammarin

2017-10-18

Vitamin D supplementation effects with or without calcium in pregnancy for reducing risk of preeclampsia and gestational or pregnancy induced hypertension are controversial. Literature was systematically searched in Medline, Scopus and Cochrane databases from inception to July 2017. Only randomized controlled trials (RCTs) in English were selected if they had any pair of interventions (calcium, vitamin D, both, or placebo). Systematic review with two-step network-meta-analysis was used to indirectly estimate supplementary effects. Twenty-seven RCTs with 28,000 women were eligible. A direct meta-analysis suggested that calcium, vitamin D, and calcium plus vitamin D could lower risk of preeclampsia when compared to placebo with the pooled risk ratios (RRs) of 0.54 (0.41, 0.70), 0.47 (0.24, 0.89) and 0.50 (0.32, 0.78), respectively. Results of network meta-analysis were similar with the corresponding RRs of 0.49 (0.35, 0.69), 0.43 (0.17, 1.11), and 0.57 (0.30, 1.10), respectively. None of the controls were significant. Efficacy of supplementation, which was ranked by surface under cumulative ranking probabilities, were: vitamin D (47.4%), calcium (31.6%) and calcium plus vitamin D (19.6%), respectively. Calcium supplementation may be used for prevention for preeclampsia. Vitamin D might also worked well but further large scale RCTs are warranted to confirm our findings.

Identification of Indirect Effects in a Cognitive Patient Education (COPE) Intervention for Low Back Pain.

PubMed

Mansell, Gemma; Storheim, Kjersti; Løchting, Ida; Werner, Erik L; Grotle, Margreth

2017-12-01

Many interventions for the treatment of low back pain exist, but the mechanisms through which such treatments work are not always clear. This situation is especially true for biopsychosocial interventions that incorporate several different components and methods of delivery. The study objective was to examine the indirect effects of the Cognitive Patient Education (COPE) intervention via illness perceptions, back pain myths, and pain catastrophizing on disability outcome. This study was a secondary analysis of the COPE randomized controlled trial. Mediation analysis techniques were employed to examine the indirect effects of the COPE intervention via residualized change (baseline - posttreatment) in the 3 variables hypothesized to be targeted by the COPE intervention on posttreatment disability outcome. Pain intensity at baseline, pain duration, clinician type, and a treatment-mediator interaction term were controlled for in the analysis. Preliminary analyses confirmed that changes in pain catastrophizing and illness perceptions (not back pain myths) were related to both allocation to the intervention arm and posttreatment disability score. The treatment exerted statistically significant indirect effects via changes in illness perceptions and pain catastrophizing on posttreatment disability score (illness perceptions standardized indirect effect = 0.09 [95% CI = 0.03 to 0.16]; pain catastrophizing standardized indirect effect = 0.05 [95% CI = 0.01 to 0.12]). However, the inclusion of an interaction term led to the indirect effects being significantly reduced, with the effects no longer being statistically significant. This study presents a secondary analysis of variables not identified a priori as being potentially important treatment targets; other, unmeasured factors could also be important in explaining treatment effects. The finding that small indirect effects of the COPE intervention via changes in illness perceptions and pain catastrophizing on posttreatment disability could be estimated indicates that these variables may be viable treatment targets for biopsychosocial interventions; however, this finding must be viewed in light of the adjusted analyses, which showed that the indirect effects were significantly reduced through the inclusion of a treatment-mediator interaction term. © Crown copyright 2015

A multiple treatment comparison meta-analysis of monoamine oxidase type B inhibitors for Parkinson's disease.

PubMed

Binde, C D; Tvete, I F; Gåsemyr, J; Natvig, B; Klemp, M

2018-05-30

To the best of our knowledge, there are no systematic reviews or meta-analyses that compare rasagiline, selegiline and safinamide. Therefore, we aimed to perform a drug class review comparing all available monoamine oxidase type B (MAO-B) inhibitors in a multiple treatment comparison. We performed a systematic literature search to identify randomized controlled trials assessing the efficacy of MAO-B inhibitors in patients with Parkinson's disease. MAO-B inhibitors were evaluated either as monotherapy or in combination with levodopa or dopamine agonists. Endpoints of interest were change in the Unified Parkinson's Disease Rating Scale (UPDRS) score and serious adverse events. We estimated the relative effect of each MAO-B inhibitor versus the comparator drug by creating three networks of direct and indirect comparisons. For each of the networks, we considered a joint model. The systematic literature search and study selection process identified 27 publications eligible for our three network analyses. We found the relative effects of rasagiline, safinamide and selegiline treatment given alone and compared to placebo in a model without explanatory variables to be 1.560 (1.409, 1.734), 1.449 (0.873, 2.413) and 1.532 (1.337, 1.757) respectively. We also found all MAO-B inhibitors to be efficient when given together with levodopa. When ranking the MAO-B inhibitors given in combination with levodopa, selegiline was the most effective and rasagiline was the second best. All of the included MAO-B inhibitors were effective compared to placebo when given as monotherapy. Combination therapy with MAO-B inhibitors and levodopa showed that all three MAO-B inhibitors were effective compared to placebo, but selegiline was the most effective drug. © 2018 The British Pharmacological Society.

Trait- and density-mediated indirect interactions initiated by an exotic invasive plant autogenic ecosystem engineer

Treesearch

Dean E. Pearson

2010-01-01

Indirect interactions are important for structuring ecological systems. However, research on indirect effects has been heavily biased toward top-down trophic interactions, and less is known about other indirect-interaction pathways. As autogenic ecosystem engineers, plants can serve as initiators of nontrophic indirect interactions that, like top-down pathways, can...

31 CFR 515.578 - Exportation of certain services incident to Internet-based communications.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Internet, such as instant messaging, chat and email, social networking, sharing of photos and movies, web... direct or indirect exportation of web-hosting services that are for purposes other than personal communications (e.g., web-hosting services for commercial endeavors) or of domain name registration services. (4...

31 CFR 515.578 - Exportation of certain services incident to Internet-based communications.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Internet, such as instant messaging, chat and email, social networking, sharing of photos and movies, web... direct or indirect exportation of web-hosting services that are for purposes other than personal communications (e.g., web-hosting services for commercial endeavors) or of domain name registration services. (4...

Feeling Good, Being Intentional, and Their Relationship to Two Types of Creativity at Work

ERIC Educational Resources Information Center

Jaussi, Kimberly S.; Knights, Alexander R.; Gupta, Alka

2017-01-01

In recent years, scholars have empirically demonstrated that creativity can be described as radical or incremental creativity. In efforts to better understand the nomological networks underlying radical and incremental creativity, this study explored the role that positive emotions directly and indirectly plays in predicting each type of…

HPC Software Stack Testing Framework

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garvey, Cormac

The HPC Software stack testing framework (hpcswtest) is used in the INL Scientific Computing Department to test the basic sanity and integrity of the HPC Software stack (Compilers, MPI, Numerical libraries and Applications) and to quickly discover hard failures, and as a by-product it will indirectly check the HPC infrastructure (network, PBS and licensing servers).

DEF: an automated dead-end filling approach based on quasi-endosymbiosis.

PubMed

Liu, Lili; Zhang, Zijun; Sheng, Taotao; Chen, Ming

2017-02-01

Gap filling for the reconstruction of metabolic networks is to restore the connectivity of metabolites via finding high-confidence reactions that could be missed in target organism. Current methods for gap filling either fall into the network topology or have limited capability in finding missing reactions that are indirectly related to dead-end metabolites but of biological importance to the target model. We present an automated dead-end filling (DEF) approach, which is derived from the wisdom of endosymbiosis theory, to fill gaps by finding the most efficient dead-end utilization paths in a constructed quasi-endosymbiosis model. The recalls of reactions and dead ends of DEF reach around 73% and 86%, respectively. This method is capable of finding indirectly dead-end-related reactions with biological importance for the target organism and is applicable to any given metabolic model. In the E. coli iJR904 model, for instance, about 42% of the dead-end metabolites were fixed by our proposed method. DEF is publicly available at http://bis.zju.edu.cn/DEF/. mchen@zju.edu.cn Supplementary data are available at Bioinformatics online.

Quantifying Direct and Indirect Effects of Elevated CO2 on Ecosystem Response

NASA Astrophysics Data System (ADS)

Fatichi, S.; Leuzinger, S.; Paschalis, A.; Donnellan-Barraclough, A.; Hovenden, M. J.; Langley, J. A.

2015-12-01

Increasing concentrations of atmospheric carbon dioxide are expected to affect carbon assimilation, evapotranspiration (ET) and ultimately plant growth. Direct leaf biochemical effects have been widely investigated, while indirect effects, although documented, are very difficult to quantify in experiments. We hypothesize that the interaction of direct and indirect effects is a possible reason for conflicting results concerning the magnitude of CO2 fertilization effects across different climates and ecosystems. A mechanistic ecohydrological model (Tethys-Chloris) is used to investigate the relative contribution of direct (through plant physiology) and indirect (via stomatal closure and thus soil moisture, and changes in Leaf Area Index, LAI) effects of elevated CO2 across a number of ecosystems. We specifically ask in which ecosystems and climate indirect effects are expected to be largest. Data and boundary conditions from flux-towers and free air CO2 enrichment (FACE) experiments are used to force the model and evaluate its performance. Numerical results suggest that indirect effects of elevated CO2, through water savings and increased LAI, are very significant and sometimes larger than direct effects. Indirect effects tend to be considerably larger in water-limited ecosystems, while direct effects correlate positively with mean air temperature. Increasing CO2 from 375 to 550 ppm causes a total effect on Net Primary Production in the order of 15 to 40% and on ET from 0 to -8%, depending on climate and ecosystem type. The total CO2 effect has a significant negative correlation with the wetness index and positive correlation with vapor pressure deficit. These results provide a more general mechanistic understanding of relatively short-term (less than 20 years) implications of elevated CO2 on ecosystem response and suggest plausible magnitudes for the expected changes.

Inferring hidden causal relations between pathway members using reduced Google matrix of directed biological networks

PubMed Central

2018-01-01

Signaling pathways represent parts of the global biological molecular network which connects them into a seamless whole through complex direct and indirect (hidden) crosstalk whose structure can change during development or in pathological conditions. We suggest a novel methodology, called Googlomics, for the structural analysis of directed biological networks using spectral analysis of their Google matrices, using parallels with quantum scattering theory, developed for nuclear and mesoscopic physics and quantum chaos. We introduce analytical “reduced Google matrix” method for the analysis of biological network structure. The method allows inferring hidden causal relations between the members of a signaling pathway or a functionally related group of genes. We investigate how the structure of hidden causal relations can be reprogrammed as a result of changes in the transcriptional network layer during cancerogenesis. The suggested Googlomics approach rigorously characterizes complex systemic changes in the wiring of large causal biological networks in a computationally efficient way. PMID:29370181

MIIC online: a web server to reconstruct causal or non-causal networks from non-perturbative data.

PubMed

Sella, Nadir; Verny, Louis; Uguzzoni, Guido; Affeldt, Séverine; Isambert, Hervé

2018-07-01

We present a web server running the MIIC algorithm, a network learning method combining constraint-based and information-theoretic frameworks to reconstruct causal, non-causal or mixed networks from non-perturbative data, without the need for an a priori choice on the class of reconstructed network. Starting from a fully connected network, the algorithm first removes dispensable edges by iteratively subtracting the most significant information contributions from indirect paths between each pair of variables. The remaining edges are then filtered based on their confidence assessment or oriented based on the signature of causality in observational data. MIIC online server can be used for a broad range of biological data, including possible unobserved (latent) variables, from single-cell gene expression data to protein sequence evolution and outperforms or matches state-of-the-art methods for either causal or non-causal network reconstruction. MIIC online can be freely accessed at https://miic.curie.fr. Supplementary data are available at Bioinformatics online.

Korea Geodetic VLBI Station, Sejong

NASA Technical Reports Server (NTRS)

Donghyun, Baek; Sangoh, Yi; Hongjong, Oh; Sangchul, Han

2013-01-01

The Sejong VLBI station officially joined the IVS as a new Network Station in 2012. This report summarizes the activities of the Sejong station during 2012. The following are the activities at the station: 1) VLBI test observations were carried out with the Tsukuba 34-m antenna of the GSI in Japan. As a result, the Sejong antenna needs to improve its efficiency, which is currently in progress, 2) A survey to connect the VLBI reference point to GNSS and ground marks was conducted, and 3) To see the indirect effects of RFI (Radio Frequency Interference) at this place, we checked the omni-direction (AZ 0? to 360?, EL fixed at 7?) for RFI influence.

Indirect effects of an invasive annual grass on seed fates of two native perennial grass species

Treesearch

Susan E. Meyer; Katherine T. Merrill; Phil S. Allen; Julie Beckstead; Anna S. Norte

2014-01-01

Invasive plants exhibit both direct and indirect negative effects on recruitment of natives following invasion. We examined indirect effects of the invader Bromus tectorum (cheatgrass) on seed fates of two native grass species, Elymus elymoides and Pseudoroegneria spicata, by removing B. tectorum and by adding inoculum of the shared seed pathogen Pyrenophora...

Indirect aerosol effect increases CMIP5 models projected Arctic warming

DOE PAGES

Chylek, Petr; Vogelsang, Timothy J.; Klett, James D.; ...

2016-02-20

Phase 5 of the Coupled Model Intercomparison Project (CMIP5) climate models’ projections of the 2014–2100 Arctic warming under radiative forcing from representative concentration pathway 4.5 (RCP4.5) vary from 0.9° to 6.7°C. Climate models with or without a full indirect aerosol effect are both equally successful in reproducing the observed (1900–2014) Arctic warming and its trends. However, the 2014–2100 Arctic warming and the warming trends projected by models that include a full indirect aerosol effect (denoted here as AA models) are significantly higher (mean projected Arctic warming is about 1.5°C higher) than those projected by models without a full indirect aerosolmore » effect (denoted here as NAA models). The suggestion is that, within models including full indirect aerosol effects, those projecting stronger future changes are not necessarily distinguishable historically because any stronger past warming may have been partially offset by stronger historical aerosol cooling. In conclusion, the CMIP5 models that include a full indirect aerosol effect follow an inverse radiative forcing to equilibrium climate sensitivity relationship, while models without it do not.« less

Indirect aerosol effect increases CMIP5 models projected Arctic warming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chylek, Petr; Vogelsang, Timothy J.; Klett, James D.

Phase 5 of the Coupled Model Intercomparison Project (CMIP5) climate models’ projections of the 2014–2100 Arctic warming under radiative forcing from representative concentration pathway 4.5 (RCP4.5) vary from 0.9° to 6.7°C. Climate models with or without a full indirect aerosol effect are both equally successful in reproducing the observed (1900–2014) Arctic warming and its trends. However, the 2014–2100 Arctic warming and the warming trends projected by models that include a full indirect aerosol effect (denoted here as AA models) are significantly higher (mean projected Arctic warming is about 1.5°C higher) than those projected by models without a full indirect aerosolmore » effect (denoted here as NAA models). The suggestion is that, within models including full indirect aerosol effects, those projecting stronger future changes are not necessarily distinguishable historically because any stronger past warming may have been partially offset by stronger historical aerosol cooling. In conclusion, the CMIP5 models that include a full indirect aerosol effect follow an inverse radiative forcing to equilibrium climate sensitivity relationship, while models without it do not.« less

Social Networks, Social Participation, and Health among Youth Living in Extreme Poverty in Rural Malawi

PubMed Central

Rock, Amelia; Barrington, Clare; Abdoulayi, Sara; Tsoka, Maxton; Mvula, Peter; Handa, Sudhanshu

2017-01-01

Extensive research documents that social network characteristics affect health, but knowledge of peer networks of youth in Malawi and sub-Saharan Africa is limited. We examine the networks and social participation of youth living in extreme poverty in rural Malawi, using in-depth interviews with 32 youth and caregivers. We describe youth’s peer networks and assess how gender and the context of extreme poverty influence their networks and participation, and how their networks influence health. In-school youth had larger, more interactive, and more supportive networks than out-of-school youth, and girls described less social participation and more isolation than boys. Youth exchanged social support and influence within their networks that helped cope with poverty-induced stress and sadness, and encouraged protective sexual health practices. However, poverty hampered their involvement in school, religious schools, and community organizations, directly through lack of required material means, and indirectly by reducing time and emotional resources and creating shame and stigma. Poverty alleviation policy holds promise for improving youth’s social wellbeing and mental and physical health by increasing their opportunities to form networks, receive social support, and experience positive influence. PMID:27760393

Social networks, social participation, and health among youth living in extreme poverty in rural Malawi.

PubMed

Rock, Amelia; Barrington, Clare; Abdoulayi, Sara; Tsoka, Maxton; Mvula, Peter; Handa, Sudhanshu

2016-12-01

Extensive research documents that social network characteristics affect health, but knowledge of peer networks of youth in Malawi and sub-Saharan Africa is limited. We examine the networks and social participation of youth living in extreme poverty in rural Malawi, using in-depth interviews with 32 youth and caregivers. We describe youth's peer networks and assess how gender and the context of extreme poverty influence their networks and participation, and how their networks influence health. In-school youth had larger, more interactive, and more supportive networks than out-of-school youth, and girls described less social participation and more isolation than boys. Youth exchanged social support and influence within their networks that helped cope with poverty-induced stress and sadness, and encouraged protective sexual health practices. However, poverty hampered their involvement in school, religious schools, and community organizations, directly by denying them required material means, and indirectly by reducing time and emotional resources and creating shame and stigma. Poverty alleviation policy holds promise for improving youth's social wellbeing and mental and physical health by increasing their opportunities to form networks, receive social support, and experience positive influence. Copyright © 2016 Elsevier Ltd. All rights reserved.

Household illness, poverty and physical and emotional child abuse victimisation: findings from South Africa's first prospective cohort study.

PubMed

Meinck, Franziska; Cluver, Lucie D; Boyes, Mark E

2015-05-01

Physical and emotional abuse of children is a large scale problem in South Africa, with severe negative outcomes for survivors. Although chronic household illness has shown to be a predictor for physical and emotional abuse, no research has thus far investigated the different pathways from household chronic illness to child abuse victimisation in South Africa. Confidential self-report questionnaires using internationally utilised measures were completed by children aged 10-17 (n = 3515, 56.7% female) using door-to-door sampling in randomly selected areas in rural and urban locations of South Africa. Follow-up surveys were conducted a year later (96.7% retention rate). Using multiple mediation analyses, this study investigated direct and indirect effects of chronic household illness (AIDS or other illness) on frequent (monthly) physical and emotional abuse victimisation with poverty and extent of the ill person's disability as hypothesised mediators. For children in AIDS-ill families, a positive direct effect on physical abuse was obtained. In addition, positive indirect effects through poverty and disability were established. For boys, a positive direct and indirect effect of AIDS-illness on emotional abuse through poverty were detected. For girls, a positive indirect effect through poverty was observed. For children in households with other chronic illness, a negative indirect effect on physical abuse was obtained. In addition, a negative indirect effect through poverty and positive indirect effect through disability was established. For boys, positive and negative indirect effects through poverty and disability were found respectively. For girls, a negative indirect effect through poverty was observed. These results indicate that children in families affected by AIDS-illness are at higher risk of child abuse victimisation, and this risk is mediated by higher levels of poverty and disability. Children affected by other chronic illness are at lower risk for abuse victimisation unless they are subject to higher levels of household disability. Interventions aiming to reduce poverty and increase family support may help prevent child abuse in families experiencing illness in South Africa.

Expanding Local Cancer Clinical Trial Options: Analysis of the Economic Impact of the Midwest Cancer Alliance in Kansas.

PubMed

Gafford, J Atlee; Gurley-Calvez, Tami; Krebill, Hope; Lai, Sue Min; Christiadi; Doolittle, Gary C

2017-09-01

Patients benefit from receiving cancer treatment closer to home when possible and at high-volume regional centers when specialized care is required. The purpose of this analysis was to estimate the economic impact of retaining more patients in-state for cancer clinical trials and care, which might offset some of the costs of establishing broader cancer trial and treatment networks. Kansas Cancer Registry data were used to estimate the number of patients retained in-state for cancer care following the expansion of local cancer clinical trial options through the Midwest Cancer Alliance based at the University of Kansas Medical Center. The 2014 economic impact of this enhanced local clinical trial network was estimated in four parts: Medical spending was estimated on the basis of National Cancer Institute cost-of-care estimates. Household travel cost savings were estimated as the difference between in-state and out-of-state travel costs. Trial-related grant income was calculated from administrative records. Indirect and induced economic benefits to the state were estimated using an economic impact model. The authors estimated that the enhanced local cancer clinical trial network resulted in approximately $6.9 million in additional economic activity in the state in 2014, or $362,000 per patient retained in-state. This estimate includes $3.6 million in direct spending and $3.3 million in indirect economic activity. The enhanced trial network also resulted in 45 additional jobs. Retaining patients in-state for cancer care and clinical trial participation allows patients to remain closer to home for care and enhances the state economy.

The Effects of Direct and Indirect Speech Acts on Native English and ESL Speakers' Perception of Teacher Written Feedback

ERIC Educational Resources Information Center

Baker, Wendy; Hansen Bricker, Rachel

2010-01-01

This study explores how second language (L2) learners perceive indirect (hedging or indirect speech acts) and direct written teacher feedback. Though research suggests that indirect speech acts may be more difficult to interpret than direct speech acts ([Champagne, 2001] and [Holtgraves, 1999]), using indirect speech acts is often encouraged in…

Disorganization and real-world functioning in schizophrenia: Results from the multicenter study of the Italian Network for Research on Psychoses.

PubMed

Rocca, P; Galderisi, S; Rossi, A; Bertolino, A; Rucci, P; Gibertoni, D; Montemagni, C; Bellino, S; Aguglia, E; Amore, M; Bellomo, A; Biondi, M; Carpiniello, B; Cuomo, A; D'Ambrosio, E; dell'Osso, L; Girardi, P; Marchesi, C; Monteleone, P; Montemitro, C; Oldani, L; Pacitti, F; Roncone, R; Siracusano, A; Tenconi, E; Vita, A; Zeppegno, P; Steardo, L; Vignapiano, A; Maj, M

2018-06-10

A general consensus has not yet been reached regarding the role of disorganization symptoms in real-world functioning in schizophrenia. We used structural equations modeling (SEM) to analyze the direct and indirect associations between disorganization and real-world functioning assessed through the Specific Levels of Functioning Scale (SLOF) in 880 subjects with schizophrenia. We found that: 1) conceptual disorganization was directly and strongly connected with SLOF daily activities; difficulty in abstract thinking was associated with moderate strength to all SLOF domains, and poor attention was connected with SLOF work skills; 2) grandiosity was only related with poor work skills, and delusions were associated with poor functioning in all SLOF domains; interpersonal relationships were weakly indirectly influenced by hallucinatory behavior, delusions and unusual thought contents through the mediation of social cognition (SC); 3) among the negative symptoms, avolition had only direct links with SLOF work skills and SLOF activities; anhedonia had direct links with SLOF work skills and SLOF interpersonal and indirect link with SLOF work skills through functional capacity (FC); asociality with SLOF interpersonal; blunted affect had direct links with SLOF activities and indirect links with SLOF interpersonal relationships mediated by SC. Lastly, alogia had only indirect links mediated by SC, FC, and neurocognition (NC). Overall conceptual disorganization is the symptom that contributed more (both directly and indirectly) to the activities of community living in real-world. Thus, it should be considered as a treatment target in intervention programs for patients with schizophrenia. Copyright © 2018. Published by Elsevier B.V.

QuIN: A Web Server for Querying and Visualizing Chromatin Interaction Networks

PubMed Central

Thibodeau, Asa; Márquez, Eladio J.; Luo, Oscar; Ruan, Yijun; Shin, Dong-Guk; Stitzel, Michael L.; Ucar, Duygu

2016-01-01

Recent studies of the human genome have indicated that regulatory elements (e.g. promoters and enhancers) at distal genomic locations can interact with each other via chromatin folding and affect gene expression levels. Genomic technologies for mapping interactions between DNA regions, e.g., ChIA-PET and HiC, can generate genome-wide maps of interactions between regulatory elements. These interaction datasets are important resources to infer distal gene targets of non-coding regulatory elements and to facilitate prioritization of critical loci for important cellular functions. With the increasing diversity and complexity of genomic information and public ontologies, making sense of these datasets demands integrative and easy-to-use software tools. Moreover, network representation of chromatin interaction maps enables effective data visualization, integration, and mining. Currently, there is no software that can take full advantage of network theory approaches for the analysis of chromatin interaction datasets. To fill this gap, we developed a web-based application, QuIN, which enables: 1) building and visualizing chromatin interaction networks, 2) annotating networks with user-provided private and publicly available functional genomics and interaction datasets, 3) querying network components based on gene name or chromosome location, and 4) utilizing network based measures to identify and prioritize critical regulatory targets and their direct and indirect interactions. AVAILABILITY: QuIN’s web server is available at http://quin.jax.org QuIN is developed in Java and JavaScript, utilizing an Apache Tomcat web server and MySQL database and the source code is available under the GPLV3 license available on GitHub: https://github.com/UcarLab/QuIN/. PMID:27336171

Supra-optimal expression of the cold-regulated OsMyb4 transcription factor in transgenic rice changes the complexity of transcriptional network with major effects on stress tolerance and panicle development.

PubMed

Park, Myoung-Ryoul; Yun, Kil-Young; Mohanty, Bijayalaxmi; Herath, Venura; Xu, Fuyu; Wijaya, Edward; Bajic, Vladimir B; Yun, Song-Joong; De Los Reyes, Benildo G

2010-12-01

The R2R3-type OsMyb4 transcription factor of rice has been shown to play a role in the regulation of osmotic adjustment in heterologous overexpression studies. However, the exact composition and organization of its underlying transcriptional network has not been established to be a robust tool for stress tolerance enhancement by regulon engineering. OsMyb4 network was dissected based on commonalities between the global chilling stress transcriptome and the transcriptome configured by OsMyb4 overexpression. OsMyb4 controls a hierarchical network comprised of several regulatory sub-clusters associated with cellular defense and rescue, metabolism and development. It regulates target genes either directly or indirectly through intermediary MYB, ERF, bZIP, NAC, ARF and CCAAT-HAP transcription factors. Regulatory sub-clusters have different combinations of MYB-like, GCC-box-like, ERD1-box-like, ABRE-like, G-box-like, as1/ocs/TGA-like, AuxRE-like, gibberellic acid response element (GARE)-like and JAre-like cis-elements. Cold-dependent network activity enhanced cellular antioxidant capacity through radical scavenging mechanisms and increased activities of phenylpropanoid and isoprenoid metabolic processes involving various abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), ethylene and reactive oxygen species (ROS) responsive genes. OsMyb4 network is independent of drought response element binding protein/C-repeat binding factor (DREB/CBF) and its sub-regulons operate with possible co-regulators including nuclear factor-Y. Because of its upstream position in the network hierarchy, OsMyb4 functions quantitatively and pleiotrophically. Supra-optimal expression causes misexpression of alternative targets with costly trade-offs to panicle development. © 2010 Blackwell Publishing Ltd.

Why CMV is a candidate for elimination and then eradication.

PubMed

Griffiths, Paul D; Mahungu, Tabitha

2016-07-01

Cytomegalovirus (CMV) is well-known for the end organ diseases (EODs) it causes following viraemic dissemination in immunocompromised hosts. These are termed the direct effects of CMV, where a diagnosis can be made in an individual patient. In addition, CMV is associated with indirect effects where populations can be seen to be disadvantaged compared to those without CMV. These indirect effects have been described in solid organ transplants, bone marrow transplants, advanced HIV, people admitted to intensive care units, the elderly and the general population. We summarise the evidence that associates CMV with its direct effects following congenital infection, solid organ transplantation, bone marrow transplantation and advanced HIV as well as its indirect effects in all patient populations. We propose that the greatest worldwide burden of CMV comes from its indirect effects. Control of this infection at the population level is being sought through the development of vaccines to control EODs where cost effectiveness is expected. We propose that the financial case for universal immunisation will be enhanced even further by the potential benefits vaccines may produce against the indirect effects of CMV.

Antithrombotic therapy in patients receiving saphenous vein coronary artery bypass grafts: a protocol for a systematic review and network meta-analysis

PubMed Central

Solo, Karla; Martin, Janet; Lavi, Shahar; Kabali, Conrad; John-Baptiste, Ava; Nevis, Immaculate F; Choudhury, Tawfiq; Mamas, Mamas A

2018-01-01

Introduction The current evidence for the prevention of saphenous vein graft failure (SVGF) after coronary artery bypass graft (CABG) surgery consists of direct head-to-head comparison of treatments (including placebo) in randomised-controlled trials (RCTs) and observational studies. However, summarising the evidence using traditional pairwise meta-analyses does not allow the inclusion of data from treatments that have not been compared head to head. Exclusion of such comparisons could impact the precision of pooled estimates in a meta-analysis. Hence, to address the challenge of whether aspirin alone or in addition to another antithrombotic agent is a more effective regimen to improve SVG patency, a network meta-analysis (NMA) is necessary. The objectives of this study are to synthesise the available evidence on antithrombotic agents (or their combination) and estimate the treatment effects among direct and indirect treatment comparisons on SVGF and major adverse cardiovascular events, and to generate a treatment ranking according to their efficacy and safety outcomes. Methods We will perform a systematic review of RCTs evaluating antithrombotic agents in patients undergoing CABG. A comprehensive English literature search will be conducted using electronic databases and grey literature resources to identify published and unpublished articles. Two individuals will independently and in duplicate screen potential studies, assess the eligibility of potential studies and extract data. Risk of bias and quality of evidence will also be evaluated independently and in duplicate. We will investigate the data to ensure its suitability for NMA, including adequacy of the outcome data and transitivity of treatment effects. We plan to estimate the pooled direct, indirect and the mixed effects for all antithrombotic agents using a NMA. Ethics and dissemination Due to the nature of the study, there are no ethical concerns nor informed consent required. We anticipate that this NMA will be the first to simultaneously assess the relative effects of multiple antithrombotic agents in patients undergoing CABG. The results of this NMA will inform clinicians, patients and guideline developers the best available evidence on comparative effects benefits of antithrombotic agents after CABG while considering the side effect profile to support future clinical decision-making. We will disseminate the results of our systematic review and NMA through a peer-reviewed journal. PROSPERO registration number CRD42017065678. PMID:29627809

Assessment of indirect losses and costs of emergency for project planning of alpine hazard mitigation

NASA Astrophysics Data System (ADS)

Amenda, Lisa; Pfurtscheller, Clemens

2013-04-01

By virtue of augmented settling in hazardous areas and increased asset values, natural disasters such as floods, landslides and rockfalls cause high economic losses in Alpine lateral valleys. Especially in small municipalities, indirect losses, mainly stemming from a breakdown of transport networks, and costs of emergency can reach critical levels. A quantification of these losses is necessary to estimate the worthiness of mitigation measures, to determine the appropriate level of disaster assistance and to improve risk management strategies. There are comprehensive approaches available for assessing direct losses. However, indirect losses and costs of emergency are widely not assessed and the empirical basis for estimating these costs is weak. To address the resulting uncertainties of project appraisals, a standardized methodology has been developed dealing with issues of local economic effects and emergency efforts needed. In our approach, the cost-benefit-analysis for technical mitigation of the Austrian Torrent and Avalanche Control (TAC) will be optimized and extended using the 2005-debris flow as a design event, which struggled a small town in the upper Inn valley in southwest Tyrol (Austria). Thereby, 84 buildings were affected, 430 people were evacuated and due to this, the TAC implemented protection measures for 3.75 million Euros. Upgrading the method of the TAC and analyzing to what extent the cost-benefit-ratio is about to change, is one of the main objectives of this study. For estimating short-run indirect effects and costs of emergency on the local level, data was collected via questionnaires, field mapping, guided interviews, as well as intense literature research. According to this, up-to-date calculation methods were evolved and the cost-benefit-analysis of TAC was recalculated with these new-implemented results. The cost-benefit-ratio will be more precise and specific and hence, the decision, which mitigation alternative will be carried out. Based on this, the worthiness of the mitigation measures can be determined in more detail and the proper level of emergency assistance can be calculated more adequately. By dint of this study, a better data basis will be created evaluating technical and non-technical mitigation measures, which is useful for government agencies, insurance companies and research.

Cognitive, personality, and social factors associated with adolescents' online personal information disclosure.

PubMed

Liu, Cong; Ang, Rebecca P; Lwin, May O

2013-08-01

The current study aims to understand the factors that influence adolescents' disclosure of personally identifiable information (PII) on social networking sites (SNSs). A survey was conducted among 780 adolescent participants (between 13 and 18) who were Facebook users. Structural equation modeling was used for analyzing the data and obtaining an overarching model that include cognitive, personality, and social factors that influence adolescents' PII disclosure. Results showed privacy concern as the cognitive factor reduces adolescents' PII disclosure and it serves as a potential mediator for personality and social factors. Amongst personality factors, narcissism was found to directly increase PII disclosure, and social anxiety indirectly decreases PII disclosure by increasing privacy concern. Amongst social factors, active parental mediation decreases PII disclosure directly and indirectly by increasing privacy concern. Restrictive parental mediation decreases PII disclosure only indirectly by increasing privacy concern. Implications of the findings to parents, educators, and policy makers were discussed. Copyright © 2013 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Viral Perturbations of Host Networks Reflect Disease Etiology

PubMed Central

Dricot, Amélie; Padi, Megha; Byrdsong, Danielle; Franchi, Rachel; Lee, Deok-Sun; Rozenblatt-Rosen, Orit; Mar, Jessica C.; Calderwood, Michael A.; Baldwin, Amy; Zhao, Bo; Santhanam, Balaji; Braun, Pascal; Simonis, Nicolas; Huh, Kyung-Won; Hellner, Karin; Grace, Miranda; Chen, Alyce; Rubio, Renee; Marto, Jarrod A.; Christakis, Nicholas A.; Kieff, Elliott; Roth, Frederick P.; Roecklein-Canfield, Jennifer; DeCaprio, James A.; Cusick, Michael E.; Quackenbush, John; Hill, David E.; Münger, Karl; Vidal, Marc; Barabási, Albert-László

2012-01-01

Many human diseases, arising from mutations of disease susceptibility genes (genetic diseases), are also associated with viral infections (virally implicated diseases), either in a directly causal manner or by indirect associations. Here we examine whether viral perturbations of host interactome may underlie such virally implicated disease relationships. Using as models two different human viruses, Epstein-Barr virus (EBV) and human papillomavirus (HPV), we find that host targets of viral proteins reside in network proximity to products of disease susceptibility genes. Expression changes in virally implicated disease tissues and comorbidity patterns cluster significantly in the network vicinity of viral targets. The topological proximity found between cellular targets of viral proteins and disease genes was exploited to uncover a novel pathway linking HPV to Fanconi anemia. PMID:22761553

Efficacy and Acceptability of Pharmacological Treatments for Depressive Disorders in Primary Care: Systematic Review and Network Meta-Analysis

PubMed Central

Linde, Klaus; Kriston, Levente; Rücker, Gerta; Jamil, Susanne; Schumann, Isabelle; Meissner, Karin; Sigterman, Kirsten; Schneider, Antonius

2015-01-01

PURPOSE The purpose of this study was to investigate whether antidepressants are more effective than placebo in the primary care setting, and whether there are differences between substance classes regarding efficacy and acceptability. METHODS We conducted literature searches in MEDLINE, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and PsycINFO up to December 2013. Randomized trials in depressed adults treated by primary care physicians were included in the review. We performed both conventional pairwise meta-analysis and network meta-analysis combining direct and indirect evidence. Main outcome measures were response and study discontinuation due to adverse effects. RESULTS A total of 66 studies with 15,161 patients met the inclusion criteria. In network meta-analysis, tricyclic and tetracyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs), a serotonin-noradrenaline reuptake inhibitor (SNRI; venlafaxine), a low-dose serotonin antagonist and reuptake inhibitor (SARI; trazodone) and hypericum extracts were found to be significantly superior to placebo, with estimated odds ratios between 1.69 and 2.03. There were no statistically significant differences between these drug classes. Reversible inhibitors of monoaminoxidase A (rMAO-As) and hypericum extracts were associated with significantly fewer dropouts because of adverse effects compared with TCAs, SSRIs, the SNRI, a noradrenaline reuptake inhibitor (NRI), and noradrenergic and specific serotonergic antidepressant agents (NaSSAs). CONCLUSIONS Compared with other drugs, TCAs and SSRIs have the most solid evidence base for being effective in the primary care setting, but the effect size compared with placebo is relatively small. Further agents (hypericum, rMAO-As, SNRI, NRI, NaSSAs, SARI) showed some positive results, but limitations of the currently available evidence makes a clear recommendation on their place in clinical practice difficult. PMID:25583895

Convolutional neural network regression for short-axis left ventricle segmentation in cardiac cine MR sequences.

PubMed

Tan, Li Kuo; Liew, Yih Miin; Lim, Einly; McLaughlin, Robert A

2017-07-01

Automated left ventricular (LV) segmentation is crucial for efficient quantification of cardiac function and morphology to aid subsequent management of cardiac pathologies. In this paper, we parameterize the complete (all short axis slices and phases) LV segmentation task in terms of the radial distances between the LV centerpoint and the endo- and epicardial contours in polar space. We then utilize convolutional neural network regression to infer these parameters. Utilizing parameter regression, as opposed to conventional pixel classification, allows the network to inherently reflect domain-specific physical constraints. We have benchmarked our approach primarily against the publicly-available left ventricle segmentation challenge (LVSC) dataset, which consists of 100 training and 100 validation cardiac MRI cases representing a heterogeneous mix of cardiac pathologies and imaging parameters across multiple centers. Our approach attained a .77 Jaccard index, which is the highest published overall result in comparison to other automated algorithms. To test general applicability, we also evaluated against the Kaggle Second Annual Data Science Bowl, where the evaluation metric was the indirect clinical measures of LV volume rather than direct myocardial contours. Our approach attained a Continuous Ranked Probability Score (CRPS) of .0124, which would have ranked tenth in the original challenge. With this we demonstrate the effectiveness of convolutional neural network regression paired with domain-specific features in clinical segmentation. Copyright © 2017 Elsevier B.V. All rights reserved.

Mathematical investigations of branch length similarity entropy profiles of shapes for various resolutions

NASA Astrophysics Data System (ADS)

Jeon, Wonju; Lee, Sang-Hee

2012-12-01

In our previous study, we defined the branch length similarity (BLS) entropy for a simple network consisting of a single node and numerous branches. As the first application of this entropy to characterize shapes, the BLS entropy profiles of 20 battle tank shapes were calculated from simple networks created by connecting pixels in the boundary of the shape. The profiles successfully characterized the tank shapes through a comparison of their BLS entropy profiles. Following the application, this entropy was used to characterize human's emotional faces, such as happiness and sad, and to measure the degree of complexity for termite tunnel networks. These applications indirectly indicate that the BLS entropy profile can be a useful tool to characterize networks and shapes. However, the ability of the BLS entropy in the characterization depends on the image resolution because the entropy is determined by the number of nodes for the boundary of a shape. Higher resolution means more nodes. If the entropy is to be widely used in the scientific community, the effect of the resolution on the entropy profile should be understood. In the present study, we mathematically investigated the BLS entropy profile of a shape with infinite resolution and numerically investigated the variation in the pattern of the entropy profile caused by changes in the resolution change in the case of finite resolution.

Elucidation of Sigma Factor-Associated Networks in Pseudomonas aeruginosa Reveals a Modular Architecture with Limited and Function-Specific Crosstalk

PubMed Central

Schulz, Sebastian; Eckweiler, Denitsa; Bielecka, Agata; Nicolai, Tanja; Franke, Raimo; Dötsch, Andreas; Hornischer, Klaus; Bruchmann, Sebastian; Düvel, Juliane; Häussler, Susanne

2015-01-01

Sigma factors are essential global regulators of transcription initiation in bacteria which confer promoter recognition specificity to the RNA polymerase core enzyme. They provide effective mechanisms for simultaneously regulating expression of large numbers of genes in response to challenging conditions, and their presence has been linked to bacterial virulence and pathogenicity. In this study, we constructed nine his-tagged sigma factor expressing and/or deletion mutant strains in the opportunistic pathogen Pseudomonas aeruginosa. To uncover the direct and indirect sigma factor regulons, we performed mRNA profiling, as well as chromatin immunoprecipitation coupled to high-throughput sequencing. We furthermore elucidated the de novo binding motif of each sigma factor, and validated the RNA- and ChIP-seq results by global motif searches in the proximity of transcriptional start sites (TSS). Our integrated approach revealed a highly modular network architecture which is composed of insulated functional sigma factor modules. Analysis of the interconnectivity of the various sigma factor networks uncovered a limited, but highly function-specific, crosstalk which orchestrates complex cellular processes. Our data indicate that the modular structure of sigma factor networks enables P. aeruginosa to function adequately in its environment and at the same time is exploited to build up higher-level functions by specific interconnections that are dominated by a participation of RpoN. PMID:25780925

Social Network Influences on Adolescent Substance Use: Disentangling Structural Equivalence from Cohesion

PubMed Central

Fujimoto, Kayo; Valente, Thomas W.

2012-01-01

This study investigates two contagion mechanisms of peer influence based on direct communication (cohesion) versus comparison through peers who occupy similar network positions (structural equivalence) in the context of adolescents' drinking alcohol and smoking. To date, the two contagion mechanisms have been considered observationally inseparable, but this study attempts to disentangle structural equivalence from cohesion as a contagion mechanism by examining the extent to which the transmission of drinking and smoking behaviors attenuates as a function of social distance (i.e., from immediate friends to indirectly connected peers). Using the U.S. Add Health data consisting of a nationally representative sample of American adolescents (Grades 7-12), this study measured peer risk-taking up to four steps away from the adolescent (friends of friends of friends of friends) using a network exposure model. Peer influence was tested using a logistic regression model of alcohol drinking and cigarette smoking. Results indicate that influence based on structural equivalence tended to be stronger than influence based on cohesion in general, and that the magnitude of the effect decreased up to three steps away from the adolescent (friends of friends of friends). Further analysis indicated that structural equivalence acted as a mechanism of contagion for drinking and cohesion acted as one for smoking. These results indicate that the two transmission mechanisms with differing network proximities can differentially affect drinking and smoking behaviors in American adolescents. PMID:22475405

Globalization to amplify economic climate losses

NASA Astrophysics Data System (ADS)

Otto, C.; Wenz, L.; Levermann, A.

2015-12-01

Economic welfare under enhanced anthropogenic carbon emissions and associated future warming poses a major challenge for a society with an evolving globally connected economy. Unabated climate change will impact economic output for example through heat-stress-related reductions in productivity. Since meteorologically-induced production reductions can propagate along supply chains, structural changes in the economic network may influence climate-related losses. The role of the economic network evolution for climate impacts has been neither quantified nor qualitatively understood. Here we show that since the beginning of the 21st century the structural change of the global supply network has been such that an increase of spillover losses due to unanticipated climatic events has to be expected. We quantify primary, secondary and higher-order losses from reduced labor productivity under past and present economic and climatic conditions and find that indirect losses are significant and increase with rising temperatures. The connectivity of the economic network has increased in such a way as to foster the propagation of production loss. This supply chain connectivity robustly exhibits the characteristic distribution of self-organized criticality which has been shifted towards higher values since 2001. Losses due to this structural evolution dominated over the effect of comparably weak climatic changes during this decade. Our finding suggests that the current form of globalization may amplify losses due to climatic extremes and thus necessitate structural adaptation that requires more foresight than presently prevalent.

Naming Game on Networks: Let Everyone be Both Speaker and Hearer

PubMed Central

Gao, Yuan; Chen, Guanrong; Chan, Rosa H. M.

2014-01-01

To investigate how consensus is reached on a large self-organized peer-to-peer network, we extended the naming game model commonly used in language and communication to Naming Game in Groups (NGG). Differing from other existing naming game models, in NGG everyone in the population (network) can be both speaker and hearer simultaneously, which resembles in a closer manner to real-life scenarios. Moreover, NGG allows the transmission (communication) of multiple words (opinions) for multiple intra-group consensuses. The communications among indirectly-connected nodes are also enabled in NGG. We simulated and analyzed the consensus process in some typical network topologies, including random-graph networks, small-world networks and scale-free networks, to better understand how global convergence (consensus) could be reached on one common word. The results are interpreted on group negotiation of a peer-to-peer network, which shows that global consensus in the population can be reached more rapidly when more opinions are permitted within each group or when the negotiating groups in the population are larger in size. The novel features and properties introduced by our model have demonstrated its applicability in better investigating general consensus problems on peer-to-peer networks. PMID:25143140

The influence of self-exempting beliefs and social networks on daily smoking: a mediation relationship explored.

PubMed

Yang, Xiaozhao Y; Kelly, Brian C; Yang, Tingzhong

2014-09-01

The decision to initiate, maintain, or quit cigarette smoking is structured by both social networks and health beliefs. Self-exempting beliefs affect people's decisions in favor of a behavior even when they recognize the harm associated with it. This study incorporated the literatures on social networks and self-exempting beliefs to study the problem of daily smoking by exploring their mediatory relationships and the mechanisms of how smoking behavior is developed and maintained. Specifically, this article hypothesizes that social networks affect daily smoking directly as well as indirectly by facilitating the formation of self-exempting beliefs. The sample comes from urban male residents in Hangzhou, China randomly selected and interviewed through multistage sampling in 2011. Using binary mediation analysis with logistic regression to test the hypotheses, the authors found that (a) daily smoking is associated with having smokers in several social network arenas and (b) self-exempting beliefs about smoking mediate the association between coworker network and daily smoking, but not for family network and friend network. The role of social network at work place in the creation and maintenance of self-exempting beliefs should be considered by policymakers, prevention experts, and interventionists.

Naming Game on Networks: Let Everyone be Both Speaker and Hearer

NASA Astrophysics Data System (ADS)

Gao, Yuan; Chen, Guanrong; Chan, Rosa H. M.

2014-08-01

To investigate how consensus is reached on a large self-organized peer-to-peer network, we extended the naming game model commonly used in language and communication to Naming Game in Groups (NGG). Differing from other existing naming game models, in NGG everyone in the population (network) can be both speaker and hearer simultaneously, which resembles in a closer manner to real-life scenarios. Moreover, NGG allows the transmission (communication) of multiple words (opinions) for multiple intra-group consensuses. The communications among indirectly-connected nodes are also enabled in NGG. We simulated and analyzed the consensus process in some typical network topologies, including random-graph networks, small-world networks and scale-free networks, to better understand how global convergence (consensus) could be reached on one common word. The results are interpreted on group negotiation of a peer-to-peer network, which shows that global consensus in the population can be reached more rapidly when more opinions are permitted within each group or when the negotiating groups in the population are larger in size. The novel features and properties introduced by our model have demonstrated its applicability in better investigating general consensus problems on peer-to-peer networks.

The Role of Mediators in the Indirect Effects of Religiosity on Therapeutic Compliance in African Migrant HIV-Positive Patients.

PubMed

Mambet Doue, Constance; Roussiau, Nicolas

2016-12-01

This research investigates the indirect effects of religiosity (practice and belief) on therapeutic compliance in 81 HIV-positive patients who are migrants from sub-Saharan Africa (23 men and 58 women). Using analyses of mediation and standard multiple regression, including a resampling procedure by bootstrapping, the role of these mediators (magical-religious beliefs and nonuse of toxic substances) was tested. The results show that, through magical-religious beliefs, religiosity has a negative indirect effect, while with the nonuse of toxic substances, religious practice has a positive indirect effect. Beyond religiosity, the role of mediators is highlighted in the interaction with therapeutic compliance.

Consecutive TMS-fMRI reveals remote effects of neural noise to the "occipital face area".

PubMed

Solomon-Harris, Lily M; Rafique, Sara A; Steeves, Jennifer K E

2016-11-01

The human cortical system for face perception comprises a network of connected regions including the middle fusiform gyrus ("fusiform face area" or FFA), the inferior occipital gyrus ("occipital face area" or OFA), and the posterior superior temporal sulcus (pSTS). Here, we sought to investigate how transcranial magnetic stimulation (TMS) to the OFA affects activity within the face processing network. We used offline repetitive TMS to temporarily introduce neural noise in the right OFA in healthy subjects. We then immediately performed functional magnetic resonance imaging (fMRI) to measure changes in blood oxygenation level dependent (BOLD) signal across the face network using an fMR-adaptation (fMR-A) paradigm. We hypothesized that TMS to the right OFA would induce abnormal face identity coding throughout the face processing network in regions to which it has direct or indirect connections. Indeed, BOLD signal for face identity, but not non-face (butterfly) identity, decreased in the right OFA and FFA following TMS to the right OFA compared to both sham TMS and TMS to a control site, the nearby object-related lateral occipital area (LO). Further, TMS to the right OFA decreased face-related activation in the left FFA, without any effect in the left OFA. Our findings indicate that TMS to the right OFA selectively disrupts face coding at both the stimulation site and bilateral FFA. TMS to the right OFA also decreased BOLD signal for different identity stimuli in the right pSTS. Together with mounting evidence from patient studies, we demonstrate connectivity of the OFA within the face network and that its activity modulates face processing in bilateral FFA as well as the right pSTS. Moreover, this study shows that deep regions within the face network can be remotely probed by stimulating structures closer to the cortical surface. Copyright © 2016 Elsevier B.V. All rights reserved.

Effective connectivity during processing of facial affect: evidence for multiple parallel pathways.

PubMed

Dima, Danai; Stephan, Klaas E; Roiser, Jonathan P; Friston, Karl J; Frangou, Sophia

2011-10-05

The perception of facial affect engages a distributed cortical network. We used functional magnetic resonance imaging and dynamic causal modeling to characterize effective connectivity during explicit (conscious) categorization of affective stimuli in the human brain. Specifically, we examined the modulation of connectivity from posterior regions of the face-processing network to the lateral ventral prefrontal cortex (VPFC) during affective categorization and we tested for a potential role of the amygdala (AMG) in mediating this modulation. We found that explicit processing of facial affect led to prominent modulation (increase) in the effective connectivity from the inferior occipital gyrus (IOG) to the VPFC, while there was less evidence for modulation of the afferent connections from fusiform gyrus and AMG to VPFC. More specifically, the forward connection from IOG to the VPFC exhibited a selective increase under anger (as opposed to fear or sadness). Furthermore, Bayesian model comparison suggested that the modulation of afferent connections to the VPFC was mediated directly by facial affect, as opposed to an indirect modulation mediated by the AMG. Our results thus suggest that affective information is conveyed to the VPFC along multiple parallel pathways and that AMG activity is not sufficient to account for the gating of information transfer to the VPFC during explicit emotional processing.

Cost-Effectiveness Model for Chemoimmunotherapy Options in Patients with Previously Untreated Chronic Lymphocytic Leukemia Unsuitable for Full-Dose Fludarabine-Based Therapy.

PubMed

Becker, Ursula; Briggs, Andrew H; Moreno, Santiago G; Ray, Joshua A; Ngo, Phuong; Samanta, Kunal

2016-06-01

To evaluate the cost-effectiveness of treatment with anti-CD20 monoclonal antibody obinutuzumab plus chlorambucil (GClb) in untreated patients with chronic lymphocytic leukemia unsuitable for full-dose fludarabine-based therapy. A Markov model was used to assess the cost-effectiveness of GClb versus other chemoimmunotherapy options. The model comprised three mutually exclusive health states: "progression-free survival (with/without therapy)", "progression (refractory/relapsed lines)", and "death". Each state was assigned a health utility value representing patients' quality of life and a specific cost value. Comparisons between GClb and rituximab plus chlorambucil or only chlorambucil were performed using patient-level clinical trial data; other comparisons were performed via a network meta-analysis using information gathered in a systematic literature review. To support the model, a utility elicitation study was conducted from the perspective of the UK National Health Service. There was good agreement between the model-predicted progression-free and overall survival and that from the CLL11 trial. On incorporating data from the indirect treatment comparisons, it was found that GClb was cost-effective with a range of incremental cost-effectiveness ratios below a threshold of £30,000 per quality-adjusted life-year gained, and remained so during deterministic and probabilistic sensitivity analyses under various scenarios. GClb was estimated to increase both quality-adjusted life expectancy and treatment costs compared with several commonly used therapies, with incremental cost-effectiveness ratios below commonly referenced UK thresholds. This article offers a real example of how to combine direct and indirect evidence in a cost-effectiveness analysis of oncology drugs. Copyright © 2016 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

Assessment of the first indirect radiative effect of ammonium-sulfate-nitrate aerosols in East Asia

NASA Astrophysics Data System (ADS)

Han, Xiao; Zhang, Meigen; Skorokhod, Andrei

2017-11-01

A physically based cloud nucleation parameterization was introduced into an optical properties/radiative transfer module incorporated with the off-line air quality modeling system Regional Atmospheric Modeling System (RAMS)-Models-3 Community Multi Scale Air Quality (CMAQ) to investigate the distribution features of the first indirect radiative effects of sulfate, nitrate, and ammonium-sulfate-nitrate (ASN) over East Asia for the years of 2005, 2010, and 2013. The relationship between aerosol particles and cloud droplet number concentration could be properly described by this parameterization because the simulated cloud fraction and cloud liquid water path were generally reliable compared with Moderate Resolution Imaging Spectroradiometer (MODIS) retrieved data. Simulation results showed that the strong effect of indirect forcing was mainly concentrated in Southeast China, the East China Sea, the Yellow Sea, and the Sea of Japan. The highest indirect radiative forcing of ASN reached -3.47 W m-2 over Southeast China and was obviously larger than the global mean of the indirect forcing of all anthropogenic aerosols. In addition, sulfate provided about half of the contribution to the ASN indirect forcing effect. However, the effect caused by nitrate was weak because the mass burden of nitrate was very low during summer, whereas the cloud fraction was the highest. The analysis indicated that even though the interannual variation of indirect forcing magnitude generally followed the trend of aerosol mass burden from 2005 to 2013, the cloud fraction was an important factor that determined the distribution pattern of indirect forcing. The heaviest aerosol loading in North China did not cause a strong radiative effect because of the low cloud fraction over this region.

Exercise as an anti-inflammatory therapy for rheumatic diseases-myokine regulation.

PubMed

Benatti, Fabiana B; Pedersen, Bente K

2015-02-01

Persistent systemic inflammation, a typical feature of inflammatory rheumatic diseases, is associated with a high cardiovascular risk and predisposes to metabolic disorders and muscle wasting. These disorders can lead to disability and decreased physical activity, exacerbating inflammation and the development of a network of chronic diseases, thus establishing a 'vicious cycle' of chronic inflammation. During the past two decades, advances in research have shed light on the role of exercise as a therapy for rheumatic diseases. One of the most important of these advances is the discovery that skeletal muscle communicates with other organs by secreting proteins called myokines. Some myokines are thought to induce anti-inflammatory responses with each bout of exercise and mediate long-term exercise-induced improvements in cardiovascular risk factors, having an indirect anti-inflammatory effect. Therefore, contrary to fears that physical activity might aggravate inflammatory pathways, exercise is now believed to be a potential treatment for patients with rheumatic diseases. In this Review, we discuss how exercise disrupts the vicious cycle of chronic inflammation directly, after each bout of exercise, and indirectly, by improving comorbidities and cardiovascular risk factors. We also discuss the mechanisms by which some myokines have anti-inflammatory functions in inflammatory rheumatic diseases.

Health Equity and Aging of Bisexual Older Adults: Pathways of Risk and Resilience

PubMed Central

Shiu, Chengshi; Bryan, Amanda E. B.; Goldsen, Jayn; Kim, Hyun-Jun

2017-01-01

Abstract Objectives: Bisexual older adults are a growing yet largely invisible, underserved, and understudied population. Utilizing the Health Equity Promotion Model, we examined hypothesized mechanisms accounting for health disparities between bisexual older adults and lesbian and gay older adults. Method: Based on data from Caring and Aging with Pride, the largest national survey of LGBT older adults, this study (N = 2,463) utilized structural equation modeling to investigate direct and indirect associations between sexual identity (bisexual vs. lesbian and gay) and health via sexual identity factors (identity disclosure and internalized stigma), social resources, and socioeconomic status (SES). Results: Bisexual older adults reported significantly poorer health compared with lesbian and gay older adults. Indirect effects involving sexual identity factors, social resources, and SES explained the association between bisexual identity and poorer health. A potentially protective pathway was also identified wherein bisexuals had larger social networks after adjusting for other factors. Discussion: Bisexual older adults face distinct challenges and health risks relative to other older adults, likely because of the accumulation of socioeconomic and psychosocial disadvantages across the life course. Interventions taking into account older bisexuals’ unique risk and protective factors may be helpful in reducing health inequities. PMID:27815302

Indirect Effects of Global Change: From Physiological and Behavioral Mechanisms to Ecological Consequences.

PubMed

Gunderson, Alex R; Tsukimura, Brian; Stillman, Jonathon H

2017-07-01

A major focus of current ecological research is to understand how global change makes species vulnerable to extirpation. To date, mechanistic ecophysiological analyses of global change vulnerability have focused primarily on the direct effects of changing abiotic conditions on whole-organism physiological traits, such as metabolic rate, locomotor performance, cardiac function, and critical thermal limits. However, species do not live in isolation within their physical environments, and direct effects of climate change are likely to be compounded by indirect effects that result from altered interactions with other species, such as competitors and predators. The Society for Integrative and Comparative Biology 2017 Symposium "Indirect Effects of Global Change: From Physiological and Behavioral Mechanisms to Ecological Consequences" was designed to synthesize multiple approaches to investigating the indirect effects of global change by bringing together researchers that study the indirect effects of global change from multiple perspectives across habitat, type of anthropogenic change, and level of biological organization. Our goal in bringing together researchers from different backgrounds was to foster cross-disciplinary insights into the mechanistic bases and higher-order ecological consequences of indirect effects of global change, and to promote collaboration among fields. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Interannual bumble bee abundance is driven by indirect climate effects on floral resource phenology.

PubMed

Ogilvie, Jane E; Griffin, Sean R; Gezon, Zachariah J; Inouye, Brian D; Underwood, Nora; Inouye, David W; Irwin, Rebecca E

2017-12-01

Climate change can influence consumer populations both directly, by affecting survival and reproduction, and indirectly, by altering resources. However, little is known about the relative importance of direct and indirect effects, particularly for species important to ecosystem functioning, like pollinators. We used structural equation modelling to test the importance of direct and indirect (via floral resources) climate effects on the interannual abundance of three subalpine bumble bee species. In addition, we used long-term data to examine how climate and floral resources have changed over time. Over 8 years, bee abundances were driven primarily by the indirect effects of climate on the temporal distribution of floral resources. Over 43 years, aspects of floral phenology changed in ways that indicate species-specific effects on bees. Our study suggests that climate-driven alterations in floral resource phenology can play a critical role in governing bee population responses to global change. © 2017 John Wiley & Sons Ltd/CNRS.

A Relational, Indirect, Meso-Level Approach to CSCL Design in the next Decade

ERIC Educational Resources Information Center

Jones, Chris; Dirckinck-Holmfeld, Lone; Lindstrom, Berner

2006-01-01

This paper reviews some foundational issues that we believe will affect the progress of CSCL over the next ten years. In particular, we examine the terms "technology", "affordance", and "infrastructure" and we propose a relational approach to their use in CSCL. Following a consideration of networks, space, and trust as conditions of productive…

Increasing the Institutional Commitment of College Students: Enhanced Measurement and Test of a Nomological Model

ERIC Educational Resources Information Center

Davidson, William B.; Beck, Hall P.; Grisaffe, Douglas B.

2015-01-01

Measurement shortcomings have hampered the understanding of institutional commitment (IC) in college students. Therefore, this study sought to (a) develop validated indices of IC and associated psychosocial attributes and (b) use these indices to test a nomological network of variables and their direct and indirect relationships to IC. Exploratory…

Mediating effects of nocturnal blood pressure and morning surge on the contributions of arterial stiffness and sodium intake to morning blood pressure: A path analysis.

PubMed

Lee, Hyung Tak; Park, Jin-Kyu; Choi, Sung Yong; Choi, Bo Youl; Kim, Mi Kyung; Mori, Mari; Yamori, Yukio; Lim, Young Hyo; Shin, Jinho

2016-01-01

The aim of this study was to evaluate the mediating effects of nocturnal blood pressure (BP) and morning surge on the contribution of arterial stiffness and sodium intake to morning BP in a middle-aged general population. The study included 124 subjects aged 30-59 years, from rural Yeoju County, Gyeonggi Province, South Korea. Ambulatory BP monitoring, 24 h urinary sodium excretion (24 h UNa) and brachial-ankle pulse wave velocity (baPWV) measurements were performed in all subjects. The mean ± SD age was 48.1 ± 8.2 years and the proportion of male subjects was 41.1%. After adjusting for covariates, morning systolic blood pressure (SBP) was significantly correlated with morning surge [coefficient = 0.761, 95% confidence interval (CI) 0.651-0.872, p < 0.001], nocturnal SBP (coefficient = 0.576, 95% CI 0.454-0.698, p < 0.001) and baPWV (coefficient = 3.550, 95% CI 1.447-5.653, p = 0.001). Path analysis modeling revealed that baPWV had significant direct (0.035, p = 0.013) and indirect effects (0.042, p = 0.012) on morning SBP. The indirect effect mediated by nocturnal SBP was statistically significant (0.054, p = 0.005), but the indirect effect mediated by the morning surge was not significant. The 24 h UNa had no significant direct or indirect effects on morning SBP. baPWV had significant direct and indirect effects on morning SBP. The indirect effect was mediated by nocturnal SBP, but not by morning surge. The 24 h UNa had neither significant direct nor indirect effects on morning SBP.

Activating and Guiding the Engagement of Seniors With Online Social Networking.

PubMed

Morton, Thomas A; Wilson, Neil; Haslam, Catherine; Birney, Megan; Kingston, Rosemary; McCloskey, Lauren-Grace

2016-08-01

Guided by theoretical and empirical work attesting to the health benefits of social connections, we tested whether Internet connectivity, and training in its use for social purposes, can support the well-being of older adults receiving care. Participants ( N = 76) were randomly assigned to receive 3 months training versus care-as-usual. Cognitive and mental health were assessed before and after the intervention. Results show significant cognitive improvements across time in the training, but not control, group. This effect was mediated through a combination of increased social activity, improved self-competence, and maintained personal identity strength. Indirect effects on mental health outcomes via these processes were also observed. These findings suggest that Internet access and training can support the self and social connectedness of vulnerable older adults and contribute positively to well-being.

Economic effects and spin-offs in a small space economy: the case of Canada.

PubMed

Amesse, Fernand; Cohendet, Patrick; Poirier, Alain; Chouinard, Jean-Marc

2002-12-01

Canada, through a well-focused space program (telecommunications, earth observation, robotics), has succeeded in developing a space industry largely based on SMEs. The result has been significant economic benefits and technological spin-offs. In this article, the results of two programs, the ESA (European Space Agency) and the STEAR (Strategic Technologies in Automation and Robotics), are compared. The ESA program has generated significant indirect effects and spin-offs for Canadian exports. ESA's reputation and network have enabled SMEs to increase export sales of both space products and other commercial products derived from space technologies. The STEAR program has been highly successful in promoting a new generation of SMEs for space robotics, encouraging both spin-in and spin-offs of technologies. The analysis highlights the complementarity of mission- and diffusion-oriented programs in the technology transfer process.

Climate change has indirect effects on resource use and overlap among coexisting bird species with negative consequences for their reproductive success

USGS Publications Warehouse

Martin, Thomas E.; Auer, Sonya K.

2013-01-01

Climate change can modify ecological interactions, but whether it can have cascading effects throughout ecological networks of multiple interacting species remains poorly studied. Climate-driven alterations in the intensity of plant–herbivore interactions may have particularly profound effects on the larger community because plants provide habitat for a wide diversity of organisms. Here we show that changes in vegetation over the last 21 years, due to climate effects on plant–herbivore interactions, have consequences for songbird nest site overlap and breeding success. Browsing-induced reductions in the availability of preferred nesting sites for two of three ground nesting songbirds led to increasing overlap in nest site characteristics among all three bird species with increasingly negative consequences for reproductive success over the long term. These results demonstrate that changes in the vegetation community from effects of climate change on plant–herbivore interactions can cause subtle shifts in ecological interactions that have critical demographic ramifications for other species in the larger community.

The Economics of Direct versus Indirect Cost Recovery in Sponsored Research. AIR Annual 1984 Forum Paper.

ERIC Educational Resources Information Center

Kutina, Kenneth L.; And Others

The effect of reduced reimbursements by the federal government for indirect research costs was analyzed for the typical academic medical center. The effects of simply cutting indirect cost reimbursement were contrasted with the impact of securing compensating levels of increased direct project support. To determine if the consequences differed as…

Aerosol indirect effect on the grid-scale clouds in the two-way coupled WRF–CMAQ: model description, development, evaluation and regional analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, S.; Mathur, R.; Pleim, J.

This study implemented first, second and glaciation aerosol indirect effects (AIE) on resolved clouds in the two-way coupled Weather Research and Forecasting Community Multiscale Air Quality (WRF–CMAQ) modeling system by including parameterizations for both cloud drop and ice number concentrations on the basis of CMAQ-predicted aerosol distributions and WRF meteorological conditions. The performance of the newly developed WRF–CMAQ model, with alternate Community Atmospheric Model (CAM) and Rapid Radiative Transfer Model for GCMs (RRTMG) radiation schemes, was evaluated with observations from the Clouds and the See http://ceres.larc.nasa.gov/. Earth's Radiant Energy System (CERES) satellite and surface monitoring networks (AQS, IMPROVE, CASTNET, STN,more » and PRISM) over the continental US (CONUS) (12 km resolution) and eastern Texas (4 km resolution) during August and September of 2006. The results at the Air Quality System (AQS) surface sites show that in August, the normalized mean bias (NMB) values for PM 2.5 over the eastern US (EUS) and the western US (WUS) are 5.3% (-0.1%) and 0.4% (-5.2%) for WRF–CMAQ/CAM (WRF–CMAQ/RRTMG), respectively. The evaluation of PM 2.5 chemical composition reveals that in August, WRF–CMAQ/CAM (WRF–CMAQ/RRTMG) consistently underestimated the observed SO 4 2- by -23.0% (-27.7%), -12.5% (-18.9%) and -7.9% (-14.8%) over the EUS at the Clean Air Status Trends Network (CASTNET), Interagency Monitoring of Protected Visual Environments (IMPROVE) and Speciated Trends Network (STN) sites, respectively. Both configurations (WRF–CMAQ/CAM, WRF–CMAQ/RRTMG) overestimated the observed mean organic carbon (OC), elemental carbon (EC) and and total carbon (TC) concentrations over the EUS in August at the IMPROVE sites. Both configurations generally underestimated the cloud field (shortwave cloud forcing, SWCF) over the CONUS in August due to the fact that the AIE on the subgrid convective clouds was not considered when the model simulations were run at the 12 km resolution. This is in agreement with the fact that both configurations captured SWCF and longwave cloud forcing (LWCF) very well for the 4 km simulation over eastern Texas, when all clouds were resolved by the finer resolution domain. The simulations of WRF–CMAQ/CAM and WRF–CMAQ/RRTMG show dramatic improvements for SWCF, LWCF, cloud optical depth (COD), cloud fractions and precipitation over the ocean relative to those of WRF default cases in August. The model performance in September is similar to that in August, except for a greater overestimation of PM 2.5 due to the overestimations of SO 4 2-, NH 4 +, NO 3 -, and TC over the EUS, less underestimation of clouds (SWCF) over the land areas due to the lower SWCF values, and fewer convective clouds in September. Finally, this work shows that inclusion of indirect aerosol effect treatments in WRF–CMAQ represents a significant advancement and milestone in air quality modeling and the development of integrated emissions control strategies for air quality management and climate change mitigation.« less

FY 2011 4th Quarter Metric: Estimate of Future Aerosol Direct and Indirect Effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koch, D

2011-09-21

The global and annual mean aerosol direct and indirect effects, relative to 1850 conditions, estimated from CESM simulations are 0.02 W m-2 and -0.39 W m-2, respectively, for emissions in year 2100 under the IPCC RCP8.5 scenario. The indirect effect is much smaller than that for 2000 emissions because of much smaller SO2 emissions in 2100; the direct effects are small due to compensation between warming by black carbon and cooling by sulfate.

The effects of temporal perspective on college students' energy drink consumption.

PubMed

Kim, Jarim; Anagondahalli, Deepa

2017-09-01

Consideration of future consequences (CFC) describes the extent to which individuals consider potential future outcomes of their present behaviors. This personality trait has been found to predict repetitive health behaviors. Research is yet to explore the role of health beliefs, which may mediate the relationship between CFC and self-directed health behaviors. Thus, this study examined how CFC affects energy drink-related health beliefs and consumption behavior. A cross-sectional correlational online survey with 1,050 college students was conducted. Key measures include the CFC Scale, health belief measures, and current energy drink consumption pattern. CFC was associated with energy drink consumption as well as several health beliefs. CFC had indirect effects on energy drink consumption through health beliefs, including perceived severity of consuming energy drinks (indirect effect estimate = -.191, 95% confidence interval [CI] [-.271, -.122]), perceived benefits of avoiding energy drinks (indirect effect estimate = -.108, 95% CI [-.174, -.050]), and perceived barriers in abstaining from energy drinks (energy level-related barriers, indirect effect estimate = -.274, 95% CI [-.387, -.181]; and socialization-related barriers, indirect effect estimate = .152, 95% CI [.078, .249]). As the first study to examine CFC's indirect effects on a self-directed health behavior through health beliefs, this study extended CFC's applicability by examining its role in the context of college students' energy drink consumption. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Direct and indirect effects of episodic frost on plant growth and reproduction in subalpine wildflowers.

PubMed

Pardee, Gabriella L; Inouye, David W; Irwin, Rebecca E

2018-02-01

Frost is an important episodic event that damages plant tissues through the formation of ice crystals at or below freezing temperatures. In montane regions, where climate change is expected to cause earlier snow melt but may not change the last frost-free day of the year, plants that bud earlier might be directly impacted by frost through damage to flower buds and reproductive structures. However, the indirect effects of frost mediated through changes in plant-pollinator interactions have rarely been explored. We examined the direct and pollinator-mediated indirect effects of frost on three wildflower species in southwestern Colorado, USA, Delphinium barbeyi (Ranunculaceae), Erigeron speciosus (Asteraceae), and Polemonium foliosissimum (Polemoniaceae), by simulating moderate (-1 to -5°C) frost events in early spring in plants in situ. Subsequently, we measured plant growth, and upon flowering measured flower morphology and phenology. Throughout the flowering season, we monitored pollinator visitation and collected seeds to measure plant reproduction. We found that frost had species-specific direct and indirect effects. Frost had direct effects on two of the three species. Frost significantly reduced flower size, total flowers produced, and seed production of Erigeron. Furthermore, frost reduced aboveground plant survival and seed production for Polemonium. However, we found no direct effects of frost on Delphinium. When we considered the indirect impacts of frost mediated through changes in pollinator visitation, one species, Erigeron, incurred indirect, negative effects of frost on plant reproduction through changes in floral traits and pollinator visitation, along with direct effects. Overall, we found that flowering plants exhibited species-specific direct and pollinator-mediated indirect responses to frost, thus suggesting that frost may play an important role in affecting plant communities under climate change. © 2017 John Wiley & Sons Ltd.

Indirect associations of combat exposure with post-deployment physical symptoms in U.S. soldiers: roles of post-traumatic stress disorder, depression and insomnia.

PubMed

Quartana, Phillip J; Wilk, Joshua E; Balkin, Thomas J; Hoge, Charles W

2015-05-01

To characterize the indirect associations of combat exposure with post-deployment physical symptoms through shared associations with post-traumatic stress disorder (PTSD), depression and insomnia symptoms. Surveys were administered to a sample of U.S. soldiers (N = 587) three months after a 15-month deployment to Iraq. A multiple indirect effects model was used to characterize direct and indirect associations between combat exposure and physical symptoms. Despite a zero-order correlation between combat exposure and physical symptoms, the multiple indirect effects analysis did not provide evidence of a direct association between these variables. Evidence for a significant indirect association of combat exposure and physical symptoms was observed through PTSD, depression, and insomnia symptoms. In fact, 92% of the total effect of combat exposure on physical symptoms scores was indirect. These findings were evident even after adjusting for the physical injury and relevant demographics. This is the first empirical study to suggest that PTSD, depression and insomnia collectively and independently contribute to the association between combat exposure and post-deployment physical symptoms. Limitations, future research directions, and potential policy implications are discussed. Published by Elsevier Inc.

Estimation of Energy Expenditure Using a Patch-Type Sensor Module with an Incremental Radial Basis Function Neural Network

PubMed Central

Li, Meina; Kwak, Keun-Chang; Kim, Youn Tae

2016-01-01

Conventionally, indirect calorimetry has been used to estimate oxygen consumption in an effort to accurately measure human body energy expenditure. However, calorimetry requires the subject to wear a mask that is neither convenient nor comfortable. The purpose of our study is to develop a patch-type sensor module with an embedded incremental radial basis function neural network (RBFNN) for estimating the energy expenditure. The sensor module contains one ECG electrode and a three-axis accelerometer, and can perform real-time heart rate (HR) and movement index (MI) monitoring. The embedded incremental network includes linear regression (LR) and RBFNN based on context-based fuzzy c-means (CFCM) clustering. This incremental network is constructed by building a collection of information granules through CFCM clustering that is guided by the distribution of error of the linear part of the LR model. PMID:27669249

Regulation of Breathing and Autonomic Outflows by Chemoreceptors

PubMed Central

Guyenet, Patrice G.

2016-01-01

Lung ventilation fluctuates widely with behavior but arterial PCO2 remains stable. Under normal conditions, the chemoreflexes contribute to PaCO2 stability by producing small corrective cardiorespiratory adjustments mediated by lower brainstem circuits. Carotid body (CB) information reaches the respiratory pattern generator (RPG) via nucleus solitarius (NTS) glutamatergic neurons which also target rostral ventrolateral medulla (RVLM) presympathetic neurons thereby raising sympathetic nerve activity (SNA). Chemoreceptors also regulate presympathetic neurons and cardiovagal preganglionic neurons indirectly via inputs from the RPG. Secondary effects of chemoreceptors on the autonomic outflows result from changes in lung stretch afferent and baroreceptor activity. Central respiratory chemosensitivity is caused by direct effects of acid on neurons and indirect effects of CO2 via astrocytes. Central respiratory chemoreceptors are not definitively identified but the retrotrapezoid nucleus (RTN) is a particularly strong candidate. The absence of RTN likely causes severe central apneas in congenital central hypoventilation syndrome. Like other stressors, intense chemosensory stimuli produce arousal and activate circuits that are wake- or attention-promoting. Such pathways (e.g., locus coeruleus, raphe, and orexin system) modulate the chemoreflexes in a state-dependent manner and their activation by strong chemosensory stimuli intensifies these reflexes. In essential hypertension, obstructive sleep apnea and congestive heart failure, chronically elevated CB afferent activity contributes to raising SNA but breathing is unchanged or becomes periodic (severe CHF). Extreme CNS hypoxia produces a stereotyped cardiorespiratory response (gasping, increased SNA). The effects of these various pathologies on brainstem cardiorespiratory networks are discussed, special consideration being given to the interactions between central and peripheral chemoreflexes. PMID:25428853

Through the looking glass: Unraveling the network structure of coal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gregory, D. M.; Stec, D. F.; Botto, R. E.

1999-12-23

Since the original idea by Sanada and Honda of treating coal as a three-dimensional cross-linked network, coal structure has been probed by monitoring ingress of solvents using traditional volumetric or gravimetric methods. However, using these techniques has allowed only an indirect observation of the swelling process. More recently, the authors have developed magnetic resonance microscopy (MRM) approaches for studying solvent ingress in polymeric systems, about which fundamental aspects of the swelling process can be deduced directly and quantitatively. The aim of their work is to utilize solvent transport and network response parameters obtained from these methods to assess fundamental propertiesmore » of the system under investigation. Polymer and coal samples have been studied to date. Numerous swelling parameters measured by magnetic resonance microscopy are found to correlate with cross-link density of the polymer network under investigation. Use of these parameters to assess the three-dimensional network structure of coal is discussed.« less

Evaluating wildlife-cattle contact rates to improve the understanding of dynamics of bovine tuberculosis transmission in Michigan, USA.

PubMed

Lavelle, Michael J; Kay, Shannon L; Pepin, Kim M; Grear, Daniel A; Campa, Henry; VerCauteren, Kurt C

2016-12-01

Direct and indirect contacts among individuals drive transmission of infectious disease. When multiple interacting species are susceptible to the same pathogen, risk assessment must include all potential host species. Bovine tuberculosis (bTB) is an example of a disease that can be transmitted among several wildlife species and to cattle, although the potential role of several wildlife species in spillback to cattle remains unclear. To better understand the complex network of contacts and factors driving disease transmission, we fitted proximity logger collars to beef and dairy cattle (n=37), white-tailed deer (Odocoileus virginianus; n=29), raccoon (Procyon lotor; n=53), and Virginia opossum (Didelphis virginiana; n=79) for 16 months in Michigan's Lower Peninsula, USA. We determined inter- and intra-species direct and indirect contact rates. Data on indirect contact was calculated when collared animals visited stationary proximity loggers placed at cattle feed and water resources. Most contact between wildlife species and cattle was indirect, with the highest contact rates occurring between raccoons and cattle during summer and fall. Nearly all visits (>99%) to cattle feed and water sources were by cattle, whereas visitation to stored cattle feed was dominated by deer and raccoon (46% and 38%, respectively). Our results suggest that indirect contact resulting from wildlife species visiting cattle-related resources could pose a risk of disease transmission to cattle and deserves continued attention with active mitigation. Published by Elsevier B.V.

Delayed in vitro development of Up states but normal network plasticity in Fragile X circuits.

PubMed

Motanis, Helen; Buonomano, Dean

2015-09-01

A broad range of neurophysiological phenotypes have been reported since the generation of the first mouse model of Fragile X syndrome (FXS). However, it remains unclear which phenotypes are causally related to the cognitive deficits associated with FXS. Indeed, because many of these phenotypes are known to be modulated by experience, a confounding factor in the interpretation of many studies is whether some phenotypes are an indirect consequence of abnormal development and experience. To help diminish this confound we first conducted an in vitro developmental study of spontaneous neural dynamics in cortical organotypic cultures. A significant developmental increase in network activity and Up states was observed in both wild-type and Fmr1(-/y) circuits, along with a specific developmental delay in the emergence of Up states in knockout circuits. To determine whether Up state regulation is generally impaired in FXS circuits, we examined Up state plasticity using chronic optogenetic stimulation. Wild-type and Fmr1(-/y) stimulated circuits exhibited a significant decrease in overall spontaneous activity including Up state frequency; however, no significant effect of genotype was observed. These results demonstrate that developmental delays characteristic of FXS are recapitulated during in vitro development, and that Up state abnormalities are probably a direct consequence of the disease, and not an indirect consequence of abnormal experience. However, the fact that Fmr1(-/y) circuits exhibited normal homeostatic modulation of Up states suggests that these plasticity mechanisms are largely intact, and that some of the previously reported plasticity deficits could reflect abnormal experience or the engagement of compensatory mechanisms. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Existence and control of Go/No-Go decision transition threshold in the striatum.

PubMed

Bahuguna, Jyotika; Aertsen, Ad; Kumar, Arvind

2015-04-01

A typical Go/No-Go decision is suggested to be implemented in the brain via the activation of the direct or indirect pathway in the basal ganglia. Medium spiny neurons (MSNs) in the striatum, receiving input from cortex and projecting to the direct and indirect pathways express D1 and D2 type dopamine receptors, respectively. Recently, it has become clear that the two types of MSNs markedly differ in their mutual and recurrent connectivities as well as feedforward inhibition from FSIs. Therefore, to understand striatal function in action selection, it is of key importance to identify the role of the distinct connectivities within and between the two types of MSNs on the balance of their activity. Here, we used both a reduced firing rate model and numerical simulations of a spiking network model of the striatum to analyze the dynamic balance of spiking activities in D1 and D2 MSNs. We show that the asymmetric connectivity of the two types of MSNs renders the striatum into a threshold device, indicating the state of cortical input rates and correlations by the relative activity rates of D1 and D2 MSNs. Next, we describe how this striatal threshold can be effectively modulated by the activity of fast spiking interneurons, by the dopamine level, and by the activity of the GPe via pallidostriatal backprojections. We show that multiple mechanisms exist in the basal ganglia for biasing striatal output in favour of either the `Go' or the `No-Go' pathway. This new understanding of striatal network dynamics provides novel insights into the putative role of the striatum in various behavioral deficits in patients with Parkinson's disease, including increased reaction times, L-Dopa-induced dyskinesia, and deep brain stimulation-induced impulsivity.

Existence and Control of Go/No-Go Decision Transition Threshold in the Striatum

PubMed Central

Bahuguna, Jyotika; Aertsen, Ad; Kumar, Arvind

2015-01-01

A typical Go/No-Go decision is suggested to be implemented in the brain via the activation of the direct or indirect pathway in the basal ganglia. Medium spiny neurons (MSNs) in the striatum, receiving input from cortex and projecting to the direct and indirect pathways express D1 and D2 type dopamine receptors, respectively. Recently, it has become clear that the two types of MSNs markedly differ in their mutual and recurrent connectivities as well as feedforward inhibition from FSIs. Therefore, to understand striatal function in action selection, it is of key importance to identify the role of the distinct connectivities within and between the two types of MSNs on the balance of their activity. Here, we used both a reduced firing rate model and numerical simulations of a spiking network model of the striatum to analyze the dynamic balance of spiking activities in D1 and D2 MSNs. We show that the asymmetric connectivity of the two types of MSNs renders the striatum into a threshold device, indicating the state of cortical input rates and correlations by the relative activity rates of D1 and D2 MSNs. Next, we describe how this striatal threshold can be effectively modulated by the activity of fast spiking interneurons, by the dopamine level, and by the activity of the GPe via pallidostriatal backprojections. We show that multiple mechanisms exist in the basal ganglia for biasing striatal output in favour of either the `Go' or the `No-Go' pathway. This new understanding of striatal network dynamics provides novel insights into the putative role of the striatum in various behavioral deficits in patients with Parkinson's disease, including increased reaction times, L-Dopa-induced dyskinesia, and deep brain stimulation-induced impulsivity. PMID:25910230

A Data-Based Approach to Discovering Multi-Topic Influential Leaders.

PubMed

Tang, Xing; Miao, Qiguang; Yu, Shangshang; Quan, Yining

2016-01-01

Recently, increasing numbers of users have adopted microblogging services as their main information source. However, most of them find themselves drowning in the millions of posts produced by other users every day. To cope with this, identifying a set of the most influential people is paramount. Moreover, finding a set of related influential users to expand the coverage of one particular topic is required in real world scenarios. Most of the existing algorithms in this area focus on topology-related methods such as PageRank. These methods mine link structures to find the expected influential rank of users. However, because they ignore the interaction data, these methods turn out to be less effective in social networks. In reality, a variety of topics exist within the information diffusing through the network. Because they have different interests, users play different roles in the diffusion of information related to different topics. As a result, distinguishing influential leaders according to different topics is also worthy of research. In this paper, we propose a multi-topic influence diffusion model (MTID) based on traces acquired from historic information. We decompose the influential scores of users into two parts: the direct influence determined by information propagation along the link structure and indirect influence that extends beyond the restrictions of direct follower relationships. To model the network from a multi-topical viewpoint, we introduce topic pools, each of which represents a particular topic information source. Then, we extract the topic distributions from the traces of tweets, determining the influence propagation probability and content generation probability. In the network, we adopt multiple ground nodes representing topic pools to connect every user through bidirectional links. Based on this multi-topical view of the network, we further introduce the topic-dependent rank (TD-Rank) algorithm to identify the multi-topic influential users. Our algorithm not only effectively overcomes the shortages of PageRank but also effectively produces a measure of topic-related rank. Extensive experiments on a Weibo dataset show that our model is both effective and robust.

A Data-Based Approach to Discovering Multi-Topic Influential Leaders

PubMed Central

Tang, Xing; Miao, Qiguang; Yu, Shangshang; Quan, Yining

2016-01-01

Recently, increasing numbers of users have adopted microblogging services as their main information source. However, most of them find themselves drowning in the millions of posts produced by other users every day. To cope with this, identifying a set of the most influential people is paramount. Moreover, finding a set of related influential users to expand the coverage of one particular topic is required in real world scenarios. Most of the existing algorithms in this area focus on topology-related methods such as PageRank. These methods mine link structures to find the expected influential rank of users. However, because they ignore the interaction data, these methods turn out to be less effective in social networks. In reality, a variety of topics exist within the information diffusing through the network. Because they have different interests, users play different roles in the diffusion of information related to different topics. As a result, distinguishing influential leaders according to different topics is also worthy of research. In this paper, we propose a multi-topic influence diffusion model (MTID) based on traces acquired from historic information. We decompose the influential scores of users into two parts: the direct influence determined by information propagation along the link structure and indirect influence that extends beyond the restrictions of direct follower relationships. To model the network from a multi-topical viewpoint, we introduce topic pools, each of which represents a particular topic information source. Then, we extract the topic distributions from the traces of tweets, determining the influence propagation probability and content generation probability. In the network, we adopt multiple ground nodes representing topic pools to connect every user through bidirectional links. Based on this multi-topical view of the network, we further introduce the topic-dependent rank (TD-Rank) algorithm to identify the multi-topic influential users. Our algorithm not only effectively overcomes the shortages of PageRank but also effectively produces a measure of topic-related rank. Extensive experiments on a Weibo dataset show that our model is both effective and robust. PMID:27415429

Role of animal movement and indirect contact among farms in transmission of porcine epidemic diarrhea virus.

PubMed

VanderWaal, Kimberly; Perez, Andres; Torremorrell, Montse; Morrison, Robert M; Craft, Meggan

2018-04-12

Epidemiological models of the spread of pathogens in livestock populations primarily focus on direct contact between farms based on animal movement data, and in some cases, local spatial spread based on proximity between premises. The roles of other types of indirect contact among farms is rarely accounted for. In addition, data on animal movements is seldom available in the United States. However, the spread of porcine epidemic diarrhea virus (PEDv) in U.S. swine represents one of the best documented emergences of a highly infectious pathogen in the U.S. livestock industry, providing an opportunity to parameterize models of pathogen spread via direct and indirect transmission mechanisms in swine. Using observed data on pig movements during the initial phase of the PEDv epidemic, we developed a network-based and spatially explicit epidemiological model that simulates the spread of PEDv via both indirect and direct movement-related contact in order to answer unresolved questions concerning factors facilitating between-farm transmission. By modifying the likelihood of each transmission mechanism and fitting this model to observed epidemiological dynamics, our results suggest that between-farm transmission was primarily driven by direct mechanisms related to animal movement and indirect mechanisms related to local spatial spread based on geographic proximity. However, other forms of indirect transmission among farms, including contact via contaminated vehicles and feed, were responsible for high consequence transmission events resulting in the introduction of the virus into new geographic areas. This research is among the first reports of farm-level animal movements in the U.S. swine industry and, to our knowledge, represents the first epidemiological model of commercial U.S. swine using actual data on farm-level animal movement. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Enhancing biological relevance of a weighted gene co-expression network for functional module identification.

PubMed

Prom-On, Santitham; Chanthaphan, Atthawut; Chan, Jonathan Hoyin; Meechai, Asawin

2011-02-01

Relationships among gene expression levels may be associated with the mechanisms of the disease. While identifying a direct association such as a difference in expression levels between case and control groups links genes to disease mechanisms, uncovering an indirect association in the form of a network structure may help reveal the underlying functional module associated with the disease under scrutiny. This paper presents a method to improve the biological relevance in functional module identification from the gene expression microarray data by enhancing the structure of a weighted gene co-expression network using minimum spanning tree. The enhanced network, which is called a backbone network, contains only the essential structural information to represent the gene co-expression network. The entire backbone network is decoupled into a number of coherent sub-networks, and then the functional modules are reconstructed from these sub-networks to ensure minimum redundancy. The method was tested with a simulated gene expression dataset and case-control expression datasets of autism spectrum disorder and colorectal cancer studies. The results indicate that the proposed method can accurately identify clusters in the simulated dataset, and the functional modules of the backbone network are more biologically relevant than those obtained from the original approach.

The Effect of Direct and Indirect Corrective Feedback on Iranian EFL Learners' Spelling Errors

ERIC Educational Resources Information Center

Ghandi, Maryam; Maghsoudi, Mojtaba

2014-01-01

The aim of the current study was to investigate the impact of indirect corrective feedback on promoting Iranian high school students' spelling accuracy in English (as a foreign language). It compared the effect of direct feedback with indirect feedback on students' written work dictated by their teacher from Chicken Soup for the Mother and…

Direct and indirect effects of body weight on adult wages.

PubMed

Han, Euna; Norton, Edward C; Powell, Lisa M

2011-12-01

Previous estimates of the association between body weight and wages in the literature have been conditional on education and occupation. In addition to the effect of current body weight status (body mass index (BMI) or obesity) on wages, this paper examines the indirect effect of body weight status in the late-teenage years on wages operating through education and occupation choice. Using the National Longitudinal Survey of Youth 1979 data, for women, we find that a one-unit increase in BMI is directly associated with 1.83% lower hourly wages whereas the indirect BMI wage penalty is not statistically significant. Neither a direct nor an indirect BMI wage penalty is found for men. However, results based on clinical weight classification reveal that the indirect wage penalty occurs to a larger extent at the upper tail of the BMI distribution for both men and women via the pathways of education and occupation outcomes. Late-teen obesity is indirectly associated with 3.5% lower hourly wages for both women and men. These results are important because they imply that the total effect of obesity on wages is significantly larger than has been estimated in previous cross-sectional studies. 2011 Elsevier B.V. All rights reserved.

Improve observation-based ground-level ozone spatial distribution by compositing satellite and surface observations: A simulation experiment

NASA Astrophysics Data System (ADS)

Zhang, Yuzhong; Wang, Yuhang; Crawford, James; Cheng, Ye; Li, Jianfeng

2018-05-01

Obtaining the full spatial coverage of daily surface ozone fields is challenging because of the sparsity of the surface monitoring network and the difficulty in direct satellite retrievals of surface ozone. We propose an indirect satellite retrieval framework to utilize the information from satellite-measured column densities of tropospheric NO2 and CH2O, which are sensitive to the lower troposphere, to derive surface ozone fields. The method is applicable to upcoming geostationary satellites with high-quality NO2 and CH2O measurements. To prove the concept, we conduct a simulation experiment using a 3-D chemical transport model for July 2011 over the eastern US. The results show that a second order regression using both NO2 and CH2O column densities can be an effective predictor for daily maximum 8-h average ozone. Furthermore, this indirect retrieval approach is shown to be complementary to spatial interpolation of surface observations, especially in regions where the surface sites are sparse. Combining column observations of NO2 and CH2O with surface site measurements leads to an improved representation of surface ozone over simple kriging, increasing the R2 value from 0.53 to 0.64 at a surface site distance of 252 km. The improvements are even more significant with larger surface site distances. The simulation experiment suggests that the indirect satellite retrieval technique can potentially be a useful tool to derive the full spatial coverage of daily surface ozone fields if satellite observation uncertainty is moderate.

Expanding Local Cancer Clinical Trial Options: Analysis of the Economic Impact of the Midwest Cancer Alliance in Kansas

PubMed Central

Gafford, J. Atlee; Krebill, Hope; Lai, Sue Min; Christiadi; Doolittle, Gary C.

2017-01-01

Purpose Patients benefit from receiving cancer treatment closer to home when possible and at high-volume regional centers when specialized care is required. The purpose of this analysis was to estimate the economic impact of retaining more patients in-state for cancer clinical trials and care, which might offset some of the costs of establishing broader cancer trial and treatment networks. Method Kansas Cancer Registry data were used to estimate the number of patients retained in-state for cancer care following the expansion of local cancer clinical trial options through the Midwest Cancer Alliance based at the University of Kansas Medical Center. The 2014 economic impact of this enhanced local clinical trial network was estimated in four parts: Medical spending was estimated on the basis of National Cancer Institute cost-of-care estimates. Household travel cost savings were estimated as the difference between in-state and out-of-state travel costs. Trial-related grant income was calculated from administrative records. Indirect and induced economic benefits to the state were estimated using an economic impact model. Results The authors estimated that the enhanced local cancer clinical trial network resulted in approximately $6.9 million in additional economic activity in the state in 2014, or $362,000 per patient retained in-state. This estimate includes $3.6 million in direct spending and $3.3 million in indirect economic activity. The enhanced trial network also resulted in 45 additional jobs. Conclusions Retaining patients in-state for cancer care and clinical trial participation allows patients to remain closer to home for care and enhances the state economy. PMID:28253204

Yes, health is important, but as much for its importance via social life: The direct and indirect effects of health on subjective well-being in chronically ill individuals.

PubMed

Lamu, Admassu N; Olsen, Jan Abel

2018-01-01

There is an increasing evidence that health-related quality of life, income, and social relationships are important to our subjective well-being (SWB). Little is known, however, about the specific indirect pathways that link health to SWB via social relationships and income. On the basis of a unique data set of 7 disease groups from 6 OECD-countries (N = 6,173), we investigate the direct and indirect effects of health on SWB by using structural equation modeling. Three alternative measures of health are used: For generic instruments (EQ-5D-5L; SF-6D), the total indirect effect was stronger (0.226; 0.249) than its direct effect (0.157; 0.205). For the visual analogue scale, the direct effect was stronger (0.322) than its total indirect effect (0.179). Most of the indirect effect of improved health on SWB transmitted through social relationships. The effect via income was small. Nevertheless, the presence of unmeasured confounders may bias the estimates. An important lesson for researchers is to include meaningful items on social relationships when measuring the benefits from improved health. An important lesson for policy makers is that social isolation appears to be more detrimental to overall well-being than ill health. Hence, the Health and Care Services should facilitate social arenas for people with chronic conditions. Copyright © 2017 John Wiley & Sons, Ltd.

Homonuclear long-range correlation spectra from HMBC experiments by covariance processing.

PubMed

Schoefberger, Wolfgang; Smrecki, Vilko; Vikić-Topić, Drazen; Müller, Norbert

2007-07-01

We present a new application of covariance nuclear magnetic resonance processing based on 1H--13C-HMBC experiments which provides an effective way for establishing indirect 1H--1H and 13C--13C nuclear spin connectivity at natural isotope abundance. The method, which identifies correlated spin networks in terms of covariance between one-dimensional traces from a single decoupled HMBC experiment, derives 13C--13C as well as 1H--1H spin connectivity maps from the two-dimensional frequency domain heteronuclear long-range correlation data matrix. The potential and limitations of this novel covariance NMR application are demonstrated on two compounds: eugenyl-beta-D-glucopyranoside and an emodin-derivative. Copyright (c) 2007 John Wiley & Sons, Ltd.

Using indirect covariance spectra to identify artifact responses in unsymmetrical indirect covariance calculated spectra.

PubMed

Martin, Gary E; Hilton, Bruce D; Blinov, Kirill A; Williams, Antony J

2008-02-01

Several groups of authors have reported studies in the areas of indirect and unsymmetrical indirect covariance NMR processing methods. Efforts have recently focused on the use of unsymmetrical indirect covariance processing methods to combine various discrete two-dimensional NMR spectra to afford the equivalent of the much less sensitive hyphenated 2D NMR experiments, for example indirect covariance (icv)-heteronuclear single quantum coherence (HSQC)-COSY and icv-HSQC-nuclear Overhauser effect spectroscopy (NOESY). Alternatively, unsymmetrical indirect covariance processing methods can be used to combine multiple heteronuclear 2D spectra to afford icv-13C-15N HSQC-HMBC correlation spectra. We now report the use of responses contained in indirect covariance processed HSQC spectra as a means for the identification of artifacts in both indirect covariance and unsymmetrical indirect covariance processed 2D NMR spectra. Copyright (c) 2007 John Wiley & Sons, Ltd.

A Structural Equation Modeling Approach to Examining Factors Influencing Outcomes with Cochlear Implant in Mandarin-Speaking Children

PubMed Central

Chen, Yuan; Wong, Lena L. N.; Zhu, Shufeng; Xi, Xin

2015-01-01

Objective To examine the direct and indirect effects of demographical factors on speech perception and vocabulary outcomes of Mandarin-speaking children with cochlear implants (CIs). Methods 115 participants implanted before the age of 5 and who had used CI before 1 to 3 years were evaluated using a battery of speech perception and vocabulary tests. Structural equation modeling was used to test the hypotheses proposed. Results Early implantation significantly contributed to speech perception outcomes while having undergone a hearing aid trial (HAT) before implantation, maternal educational level (MEL), and having undergone universal newborn hearing screening (UNHS) before implantation had indirect effects on speech perception outcomes via their effects on age at implantation. In addition, both age at implantation and MEL had direct and indirect effects on vocabulary skills, while UNHS and HAT had indirect effects on vocabulary outcomes via their effects on age at implantation. Conclusion A number of factors had indirect and direct effects on speech perception and vocabulary outcomes in Mandarin-speaking children with CIs and these factors were not necessarily identical to those reported among their English-speaking counterparts. PMID:26348360

Indirect genetic effects from competition in the clonal herb Sedum album (Crassulaceae).

PubMed

Andersson, Stefan

2014-01-01

Recent years have seen increasing interest in indirect genetic effects, i.e. influences on the phenotype that depend on the genotype of other conspecific individuals; however, the empirical evidence for such effects is still limited, especially in wild plant species. The present study of the clonal herb Sedum album assessed direct and indirect genetic effects on performance-related traits in a 4-year experiment with clonally replicated genotypes, grown in pairs and differing in anthocyanin pigmentation to allow separation of individuals during data collection. In agreement with the existence of indirect genetic effects, the experimentally-paired plants not only expressed their own genotype but were also affected by the genotype of their pair mate. The effect of neighbour genotype explained up to one-fourth of the variation in performance and most likely resulted from competition, imposed by the close physical contact between paired individuals and the limiting conditions used in the garden environment. Indirect genetic effects from competition have the potential to enhance the efficacy of group-level selection relative to individual selection, given the nutrient-poor and spatially-confined substrate available to plants of S. album in the natural habitat.

The effect of different spectral shape parameterizations of cloud droplet size distribution on first and second aerosol indirect effects in NACR CAM5 and evaluation with satellite data

NASA Astrophysics Data System (ADS)

Wang, M.; Peng, Y.; Xie, X.; Liu, Y.

2017-12-01

Aerosol cloud interaction continues to constitute one of the most significant uncertainties for anthropogenic climate perturbations. The parameterization of cloud droplet size distribution and autoconversion process from large scale cloud to rain can influence the estimation of first and second aerosol indirect effects in global climate models. We design a series of experiments focusing on the microphysical cloud scheme of NCAR CAM5 (Community Atmospheric Model Version 5) in transient historical run with realistic sea surface temperature and sea ice. We investigate the effect of three empirical, two semi-empirical and one analytical expressions for droplet size distribution on cloud properties and explore the statistical relationships between aerosol optical thickness (AOT) and simulated cloud variables, including cloud top droplet effective radius (CDER), cloud optical depth (COD), cloud water path (CWP). We also introduce the droplet spectral shape parameter into the autoconversion process to incorporate the effect of droplet size distribution on second aerosol indirect effect. Three satellite datasets (MODIS Terra/ MODIS Aqua/ AVHRR) are used to evaluate the simulated aerosol indirect effect from the model. Evident CDER decreasing with significant AOT increasing is found in the east coast of China to the North Pacific Ocean and the east coast of USA to the North Atlantic Ocean. Analytical and semi-empirical expressions for spectral shape parameterization show stronger first aerosol indirect effect but weaker second aerosol indirect effect than empirical expressions because of the narrower droplet size distribution.

[Characteristics of social supportive network serving the older female sex workers in Qingdao].

PubMed

Xu, Y Q; Li, Y F; Jiang, Z X; Zhang, X J; Yuan, X; Zhang, N; Li, X F; Jiang, B F

2016-02-01

To overview the status of social support on older female sex workers (OFSWs) in Qingdao and to better understand the characteristics of this egocentric social support networks. Ucinet 6 software was used to analyze the characteristics of egocentric social networks which involving 400 OFSWs who were recruited by respondent-driven sampling (RDS) method in Qingdao during March 2014 to June. Structural equation model (SEM) was used for data analysis, fitted test and estimation. A total of 400 OFSWs of Qingdao nominated 1 617 social supportive members, and the average size of egocentric social networks of OFSWs was (4.0 ± 1.5). Among all the alter egos (social support network members of the egos), 613 were female sex workers fellows, accounted for the most important part of all the social ties (37.91%). Characteristics of small size and non-relative relationships were seen more obviously among OFSWs with non-local registration and the ratings of emotional support (4.42±2.38) was significantly lower than the tangible support (5.73 ± 1.69) (P<0.05). Result of the SEM showed that homogeneity, joint strength and the network structure were significantly related to the ratings of average support. The total standard effects of which were 0.110, 0.925 and -0.069 respectively. It seemed that homogeneity can affect the degree of support, both directly and indirectly. OFSWs in Qingdao tended to ask for social support from friends who were also female sex workers. Stronger the joint strength between egos and alters, greater the homogeneity between the two was seen. Tighter relations among the alter egos, higher degree of average social support of the egos were acquired.

Teaching artificial neural systems to drive: Manual training techniques for autonomous systems

NASA Technical Reports Server (NTRS)

Shepanski, J. F.; Macy, S. A.

1987-01-01

A methodology was developed for manually training autonomous control systems based on artificial neural systems (ANS). In applications where the rule set governing an expert's decisions is difficult to formulate, ANS can be used to extract rules by associating the information an expert receives with the actions taken. Properly constructed networks imitate rules of behavior that permits them to function autonomously when they are trained on the spanning set of possible situations. This training can be provided manually, either under the direct supervision of a system trainer, or indirectly using a background mode where the networks assimilates training data as the expert performs its day-to-day tasks. To demonstrate these methods, an ANS network was trained to drive a vehicle through simulated freeway traffic.

Synchronization in dynamical networks with unconstrained structure switching

NASA Astrophysics Data System (ADS)

del Genio, Charo I.; Romance, Miguel; Criado, Regino; Boccaletti, Stefano

2015-12-01

We provide a rigorous solution to the problem of constructing a structural evolution for a network of coupled identical dynamical units that switches between specified topologies without constraints on their structure. The evolution of the structure is determined indirectly from a carefully built transformation of the eigenvector matrices of the coupling Laplacians, which are guaranteed to change smoothly in time. In turn, this allows one to extend the master stability function formalism, which can be used to assess the stability of a synchronized state. This approach is independent from the particular topologies that the network visits, and is not restricted to commuting structures. Also, it does not depend on the time scale of the evolution, which can be faster than, comparable to, or even secular with respect to the dynamics of the units.

Scientific collaboration and endorsement: Network analysis of coauthorship and citation networks

PubMed Central

Ding, Ying

2010-01-01

Scientific collaboration and endorsement are well-established research topics which utilize three kinds of methods: survey/questionnaire, bibliometrics, and complex network analysis. This paper combines topic modeling and path-finding algorithms to determine whether productive authors tend to collaborate with or cite researchers with the same or different interests, and whether highly cited authors tend to collaborate with or cite each other. Taking information retrieval as a test field, the results show that productive authors tend to directly coauthor with and closely cite colleagues sharing the same research interests; they do not generally collaborate directly with colleagues having different research topics, but instead directly or indirectly cite them; and highly cited authors do not generally coauthor with each other, but closely cite each other. PMID:21344057

Developmental cascade models linking peer victimization, depression, and academic achievement in Chinese children.

PubMed

Liu, Junsheng; Bullock, Amanda; Coplan, Robert J; Chen, Xinyin; Li, Dan; Zhou, Ying

2018-03-01

This study explored the longitudinal relations among peer victimization, depression, and academic achievement in Chinese primary school students. Participants were N = 945 fourth-grade students (485 boys, 460 girls; M age  = 10.16 years, SD = 2 months) attending elementary schools in Shanghai, People's Republic of China. Three waves of data on peer victimization, depression, and academic achievement were collected from peer nominations, self-reports, and school records, respectively. The results indicated that peer victimization had both direct and indirect effects on later depression and academic achievement. Depression also had both direct and indirect negative effects on later academic achievement, but demonstrated only an indirect effect on later peer victimization. Finally, academic achievement had both direct and indirect negative effects on later peer victimization and depression. The findings show that there are cross-cultural similarities and differences in the various transactions that exist among peer victimization, depression, and academic achievement. Statement of contribution What is already known on this subject? Peer victimization directly and indirectly relates to depression and academic achievement. Depression directly and indirectly relates to academic achievement. Academic achievement directly and indirectly relates to depression. What the present study adds? A developmental cascade approach was used to assess the interrelations among peer victimization, depression, and academic achievement. Academic achievement mediates the relation between peer victimization and depression. Depression is related to peer victimization through academic achievement. Academic achievement directly and indirectly relates to peer victimization. Academic achievement is related to depression through peer victimization. © 2017 The British Psychological Society.

An invasive herbivore structures plant competitive dynamics.

PubMed

Wong, Lydia; Grainger, Tess Nahanni; Start, Denon; Gilbert, Benjamin

2017-11-01

Species interactions are central to our understanding of ecological communities, but may change rapidly with the introduction of invasive species. Invasive species can alter species interactions and community dynamics directly by having larger detrimental effects on some species than others, or indirectly by changing the ways in which native species compete among themselves. We tested the direct and indirect effects of an invasive aphid herbivore on a native aphid species and two host milkweed species. The invasive aphid caused a 10-fold decrease in native aphid populations, and a 30% increase in plant mortality (direct effects). The invasive aphid also increased the strength of interspecific competition between the two native plant hosts (indirect effects). By investigating the role that indirect effects play in shaping species interactions in native communities, our study highlights an understudied component of species invasions. © 2017 The Author(s).

Hippocampal Ripple Oscillations and Inhibition-First Network Models: Frequency Dynamics and Response to GABA Modulators.

PubMed

Donoso, José R; Schmitz, Dietmar; Maier, Nikolaus; Kempter, Richard

2018-03-21

Hippocampal ripples are involved in memory consolidation, but the mechanisms underlying their generation remain unclear. Models relying on interneuron networks in the CA1 region disagree on the predominant source of excitation to interneurons: either "direct," via the Schaffer collaterals that provide feedforward input from CA3 to CA1, or "indirect," via the local pyramidal cells in CA1, which are embedded in a recurrent excitatory-inhibitory network. Here, we used physiologically constrained computational models of basket-cell networks to investigate how they respond to different conditions of transient, noisy excitation. We found that direct excitation of interneurons could evoke ripples (140-220 Hz) that exhibited intraripple frequency accommodation and were frequency-insensitive to GABA modulators, as previously shown in in vitro experiments. In addition, the indirect excitation of the basket-cell network enabled the expression of intraripple frequency accommodation in the fast-gamma range (90-140 Hz), as in vivo In our model, intraripple frequency accommodation results from a hysteresis phenomenon in which the frequency responds differentially to the rising and descending phases of the transient excitation. Such a phenomenon predicts a maximum oscillation frequency occurring several milliseconds before the peak of excitation. We confirmed this prediction for ripples in brain slices from male mice. These results suggest that ripple and fast-gamma episodes are produced by the same interneuron network that is recruited via different excitatory input pathways, which could be supported by the previously reported intralaminar connectivity bias between basket cells and functionally distinct subpopulations of pyramidal cells in CA1. Together, our findings unify competing inhibition-first models of rhythm generation in the hippocampus. SIGNIFICANCE STATEMENT The hippocampus is a part of the brain of humans and other mammals that is critical for the acquisition and consolidation of memories. During deep sleep and resting periods, the hippocampus generates high-frequency (∼200 Hz) oscillations called ripples, which are important for memory consolidation. The mechanisms underlying ripple generation are not well understood. A prominent hypothesis holds that the ripples are generated by local recurrent networks of inhibitory neurons. Using computational models and experiments in brain slices from rodents, we show that the dynamics of interneuron networks clarify several previously unexplained characteristics of ripple oscillations, which advances our understanding of hippocampus-dependent memory consolidation. Copyright © 2018 the authors 0270-6474/18/383125-23$15.00/0.

Social network models predict movement and connectivity in ecological landscapes

USGS Publications Warehouse

Fletcher, R.J.; Acevedo, M.A.; Reichert, Brian E.; Pias, Kyle E.; Kitchens, W.M.

2011-01-01

Network analysis is on the rise across scientific disciplines because of its ability to reveal complex, and often emergent, patterns and dynamics. Nonetheless, a growing concern in network analysis is the use of limited data for constructing networks. This concern is strikingly relevant to ecology and conservation biology, where network analysis is used to infer connectivity across landscapes. In this context, movement among patches is the crucial parameter for interpreting connectivity but because of the difficulty of collecting reliable movement data, most network analysis proceeds with only indirect information on movement across landscapes rather than using observed movement to construct networks. Statistical models developed for social networks provide promising alternatives for landscape network construction because they can leverage limited movement information to predict linkages. Using two mark-recapture datasets on individual movement and connectivity across landscapes, we test whether commonly used network constructions for interpreting connectivity can predict actual linkages and network structure, and we contrast these approaches to social network models. We find that currently applied network constructions for assessing connectivity consistently, and substantially, overpredict actual connectivity, resulting in considerable overestimation of metapopulation lifetime. Furthermore, social network models provide accurate predictions of network structure, and can do so with remarkably limited data on movement. Social network models offer a flexible and powerful way for not only understanding the factors influencing connectivity but also for providing more reliable estimates of connectivity and metapopulation persistence in the face of limited data.

Using FastX on the Peregrine System | High-Performance Computing | NREL

Science.gov Websites

with full 3D hardware acceleration. The traditional method of displaying graphics applications to a remote X server (indirect rendering) supports 3D hardware acceleration, but this approach causes all of the OpenGL commands and 3D data to be sent over the network to be rendered on the client machine. With

The genetic regulatory network centered on Pto-Wuschela and its targets involved in wood formation revealed by association studies.

PubMed

Yang, Xiaohui; Wei, Zunzheng; Du, Qingzhang; Chen, Jinhui; Wang, Qingshi; Quan, Mingyang; Song, Yuepeng; Xie, Jianbo; Zhang, Deqiang

2015-11-09

Transcription factors (TFs) regulate gene expression and can strongly affect phenotypes. However, few studies have examined TF variants and TF interactions with their targets in plants. Here, we used genetic association in 435 unrelated individuals of Populus tomentosa to explore the variants in Pto-Wuschela and its targets to decipher the genetic regulatory network of Pto-Wuschela. Our bioinformatics and co-expression analysis identified 53 genes with the motif TCACGTGA as putative targets of Pto-Wuschela. Single-marker association analysis showed that Pto-Wuschela was associated with wood properties, which is in agreement with the observation that it has higher expression in stem vascular tissues in Populus. Also, SNPs in the 53 targets were associated with growth or wood properties under additive or dominance effects, suggesting these genes and Pto-Wuschela may act in the same genetic pathways that affect variation in these quantitative traits. Epistasis analysis indicated that 75.5% of these genes directly or indirectly interacted Pto-Wuschela, revealing the coordinated genetic regulatory network formed by Pto-Wuschela and its targets. Thus, our study provides an alternative method for dissection of the interactions between a TF and its targets, which will strength our understanding of the regulatory roles of TFs in complex traits in plants.

Powerful Voter Selection for Making Multistep Delegate Ballot Fair

NASA Astrophysics Data System (ADS)

Yamakawa, Hiroshi

For decision by majority, each voter often exercises his right by delegating to trustable other voters. Multi-step delegates rule allows indirect delegating through more than one voter, and this helps each voter finding his delegate voters. In this paper, we propose powerful voter selection method depending on the multi-step delegate rule. This method sequentially selects voters who is most delegated indirectly. Multi-agent simulation demonstrate that we can achieve highly fair poll results from small number of vote by using proposed method. Here, fairness is prediction accuracy to sum of all voters preferences for choices. In simulation, each voter selects choices arranged on one dimensional preference axis for voting. Acquaintance relationships among voters were generated as a random network, and each voter delegates some of his acquaintances who has similar preferences. We obtained simulation results from various acquaintance networks, and then averaged these results. Firstly, if each voter has enough acquaintances in average, proposed method can help predicting sum of all voters' preferences of choices from small number of vote. Secondly, if the number of each voter's acquaintances increases corresponding to an increase in the number of voters, prediction accuracy (fairness) from small number of vote can be kept in appropriate level.

Power Management Based Current Control Technique for Photovoltaic-Battery Assisted Wind-Hydro Hybrid System

NASA Astrophysics Data System (ADS)

Ram Prabhakar, J.; Ragavan, K.

2013-07-01

This article proposes new power management based current control strategy for integrated wind-solar-hydro system equipped with battery storage mechanism. In this control technique, an indirect estimation of load current is done, through energy balance model, DC-link voltage control and droop control. This system features simpler energy management strategy and necessitates few power electronic converters, thereby minimizing the cost of the system. The generation-demand (G-D) management diagram is formulated based on the stochastic weather conditions and demand, which would likely moderate the gap between both. The features of management strategy deploying energy balance model include (1) regulating DC-link voltage within specified tolerances, (2) isolated operation without relying on external electric power transmission network, (3) indirect current control of hydro turbine driven induction generator and (4) seamless transition between grid-connected and off-grid operation modes. Furthermore, structuring of the hybrid system with appropriate selection of control variables enables power sharing among each energy conversion systems and battery storage mechanism. By addressing these intricacies, it is viable to regulate the frequency and voltage of the remote network at load end. The performance of the proposed composite scheme is demonstrated through time-domain simulation in MATLAB/Simulink environment.

Wildlife contact analysis: Emerging methods, questions, and challenges

USGS Publications Warehouse

Cross, Paul C.; Creech, Tyler G.; Ebinger, Michael R.; Heisey, Dennis M.; Irvine, Kathryn M.; Creel, Scott

2012-01-01

Recent technological advances, such as proximity loggers, allow researchers to collect complete interaction histories, day and night, among sampled individuals over several months to years. Social network analyses are an obvious approach to analyzing interaction data because of their flexibility for fitting many different social structures as well as the ability to assess both direct contacts and indirect associations via intermediaries. For many network properties, however, it is not clear whether estimates based upon a sample of the network are reflective of the entire network. In wildlife applications, networks may be poorly sampled and boundary effects will be common. We present an alternative approach that utilizes a hierarchical modeling framework to assess the individual, dyadic, and environmental factors contributing to variation in the interaction rates and allows us to estimate the underlying process variation in each. In a disease control context, this approach will allow managers to focus efforts on those types of individuals and environments that contribute the most toward super-spreading events. We account for the sampling distribution of proximity loggers and the non-independence of contacts among groups by only using contact data within a group during days when the group membership of proximity loggers was known. This allows us to separate the two mechanisms responsible for a pair not contacting one another: they were not in the same group or they were in the same group but did not come within the specified contact distance. We illustrate our approach with an example dataset of female elk from northwestern Wyoming and conclude with a number of important future research directions.

Foxp2 Regulates Gene Networks Implicated in Neurite Outgrowth in the Developing Brain

PubMed Central

Vernes, Sonja C.; Oliver, Peter L.; Spiteri, Elizabeth; Lockstone, Helen E.; Puliyadi, Rathi; Taylor, Jennifer M.; Ho, Joses; Mombereau, Cedric; Brewer, Ariel; Lowy, Ernesto; Nicod, Jérôme; Groszer, Matthias; Baban, Dilair; Sahgal, Natasha; Cazier, Jean-Baptiste; Ragoussis, Jiannis; Davies, Kay E.; Geschwind, Daniel H.; Fisher, Simon E.

2011-01-01

Forkhead-box protein P2 is a transcription factor that has been associated with intriguing aspects of cognitive function in humans, non-human mammals, and song-learning birds. Heterozygous mutations of the human FOXP2 gene cause a monogenic speech and language disorder. Reduced functional dosage of the mouse version (Foxp2) causes deficient cortico-striatal synaptic plasticity and impairs motor-skill learning. Moreover, the songbird orthologue appears critically important for vocal learning. Across diverse vertebrate species, this well-conserved transcription factor is highly expressed in the developing and adult central nervous system. Very little is known about the mechanisms regulated by Foxp2 during brain development. We used an integrated functional genomics strategy to robustly define Foxp2-dependent pathways, both direct and indirect targets, in the embryonic brain. Specifically, we performed genome-wide in vivo ChIP–chip screens for Foxp2-binding and thereby identified a set of 264 high-confidence neural targets under strict, empirically derived significance thresholds. The findings, coupled to expression profiling and in situ hybridization of brain tissue from wild-type and mutant mouse embryos, strongly highlighted gene networks linked to neurite development. We followed up our genomics data with functional experiments, showing that Foxp2 impacts on neurite outgrowth in primary neurons and in neuronal cell models. Our data indicate that Foxp2 modulates neuronal network formation, by directly and indirectly regulating mRNAs involved in the development and plasticity of neuronal connections. PMID:21765815

Foxp2 regulates gene networks implicated in neurite outgrowth in the developing brain.

PubMed

Vernes, Sonja C; Oliver, Peter L; Spiteri, Elizabeth; Lockstone, Helen E; Puliyadi, Rathi; Taylor, Jennifer M; Ho, Joses; Mombereau, Cedric; Brewer, Ariel; Lowy, Ernesto; Nicod, Jérôme; Groszer, Matthias; Baban, Dilair; Sahgal, Natasha; Cazier, Jean-Baptiste; Ragoussis, Jiannis; Davies, Kay E; Geschwind, Daniel H; Fisher, Simon E

2011-07-01

Forkhead-box protein P2 is a transcription factor that has been associated with intriguing aspects of cognitive function in humans, non-human mammals, and song-learning birds. Heterozygous mutations of the human FOXP2 gene cause a monogenic speech and language disorder. Reduced functional dosage of the mouse version (Foxp2) causes deficient cortico-striatal synaptic plasticity and impairs motor-skill learning. Moreover, the songbird orthologue appears critically important for vocal learning. Across diverse vertebrate species, this well-conserved transcription factor is highly expressed in the developing and adult central nervous system. Very little is known about the mechanisms regulated by Foxp2 during brain development. We used an integrated functional genomics strategy to robustly define Foxp2-dependent pathways, both direct and indirect targets, in the embryonic brain. Specifically, we performed genome-wide in vivo ChIP-chip screens for Foxp2-binding and thereby identified a set of 264 high-confidence neural targets under strict, empirically derived significance thresholds. The findings, coupled to expression profiling and in situ hybridization of brain tissue from wild-type and mutant mouse embryos, strongly highlighted gene networks linked to neurite development. We followed up our genomics data with functional experiments, showing that Foxp2 impacts on neurite outgrowth in primary neurons and in neuronal cell models. Our data indicate that Foxp2 modulates neuronal network formation, by directly and indirectly regulating mRNAs involved in the development and plasticity of neuronal connections.

Different Roles of Direct and Indirect Frontoparietal Pathways for Individual Working Memory Capacity.

PubMed

Ekman, Matthias; Fiebach, Christian J; Melzer, Corina; Tittgemeyer, Marc; Derrfuss, Jan

2016-03-09

The ability to temporarily store and manipulate information in working memory is a hallmark of human intelligence and differs considerably across individuals, but the structural brain correlates underlying these differences in working memory capacity (WMC) are only poorly understood. In two separate studies, diffusion MRI data and WMC scores were collected for 70 and 109 healthy individuals. Using a combination of probabilistic tractography and network analysis of the white matter tracts, we examined whether structural brain network properties were predictive of individual WMC. Converging evidence from both studies showed that lateral prefrontal cortex and posterior parietal cortex of high-capacity individuals are more densely connected compared with low-capacity individuals. Importantly, our network approach was further able to dissociate putative functional roles associated with two different pathways connecting frontal and parietal regions: a corticocortical pathway and a subcortical pathway. In Study 1, where participants were required to maintain and update working memory items, the connectivity of the direct and indirect pathway was predictive of WMC. In contrast, in Study 2, where participants were required to maintain working memory items without updating, only the connectivity of the direct pathway was predictive of individual WMC. Our results suggest an important dissociation in the circuitry connecting frontal and parietal regions, where direct frontoparietal connections might support storage and maintenance, whereas subcortically mediated connections support the flexible updating of working memory content. Copyright © 2016 the authors 0270-6474/16/362894-10$15.00/0.

Importance of latrine communication in European rabbits shifts along a rural-to-urban gradient.

PubMed

Ziege, Madlen; Bierbach, David; Bischoff, Svenja; Brandt, Anna-Lena; Brix, Mareike; Greshake, Bastian; Merker, Stefan; Wenninger, Sandra; Wronski, Torsten; Plath, Martin

2016-06-14

Information transfer in mammalian communication networks is often based on the deposition of excreta in latrines. Depending on the intended receiver(s), latrines are either formed at territorial boundaries (between-group communication) or in core areas of home ranges (within-group communication). The relative importance of both types of marking behavior should depend, amongst other factors, on population densities and social group sizes, which tend to differ between urban and rural wildlife populations. Our study is the first to assess (direct and indirect) anthropogenic influences on mammalian latrine-based communication networks along a rural-to-urban gradient in European rabbits (Oryctolagus cuniculus) living in urban, suburban and rural areas in and around Frankfurt am Main (Germany). The proportion of latrines located in close proximity to the burrow was higher at rural study sites compared to urban and suburban ones. At rural sites, we found the largest latrines and highest latrine densities close to the burrow, suggesting that core marking prevailed. By contrast, latrine dimensions and densities increased with increasing distance from the burrow in urban and suburban populations, suggesting a higher importance of peripheral marking. Increased population densities, but smaller social group sizes in urban rabbit populations may lead to an increased importance of between-group communication and thus, favor peripheral over core marking. Our study provides novel insights into the manifold ways by which man-made habitat alterations along a rural-to-urban gradient directly and indirectly affect wildlife populations, including latrine-based communication networks.

Using indirect comparisons to compare interventions within a Cochrane review: a tool for comparative effectiveness research.

PubMed

Agapova, Maria; Devine, Emily B; Nguyen, Hiep; Wolf, Fredric M; Inoue, Lurdes Y T

2014-07-01

Assessing relative performance among competing interventions is an important part of comparative effectiveness research. Bayesian indirect comparisons add information to existing Cochrane reviews, such as which intervention is likely to perform best. However, heterogeneity variance priors may influence results and, potentially, clinical guidance. We highlight the features of Bayesian indirect comparisons using a case study of a Cochrane review update in asthma care. The probability that one self-management educational intervention outperforms others is estimated. Simulation studies investigate the effect of heterogeneity variance prior distributions. Results suggest a 55% probability that individual education is best, followed by combination (39%) and group (6%). The intervention with few trials was sensitive to prior distributions. Bayesian indirect comparisons updates of Cochrane reviews are valuable comparative effectiveness research tools.

Comparison of pharmacological and non-pharmacological interventions to prevent delirium in critically ill patients: a protocol for a systematic review incorporating network meta-analyses.

PubMed

Burry, L D; Hutton, B; Guenette, M; Williamson, D; Mehta, S; Egerod, I; Kanji, S; Adhikari, N K; Moher, D; Martin, C M; Rose, L

2016-09-08

Delirium is characterized by acute changes in mental status including inattention, disorganized thinking, and altered level of consciousness, and is highly prevalent in critically ill adults. Delirium has adverse consequences for both patients and the healthcare system; however, at this time, no effective treatment exists. The identification of effective prevention strategies is therefore a clinical and research imperative. An important limitation of previous reviews of delirium prevention is that interventions were considered in isolation and only direct evidence was used. Our systematic review will synthesize all existing data using network meta-analysis, a powerful statistical approach that enables synthesis of both direct and indirect evidence. We will search Ovid MEDLINE, CINAHL, Embase, PsycINFO, and Web of Science from 1980 to March 2016. We will search the PROSPERO registry for protocols and the Cochrane Library for published systematic reviews. We will examine reference lists of pertinent reviews and search grey literature and the International Clinical Trials Registry Platform for unpublished studies and ongoing trials. We will include randomized and quasi-randomized trials of critically ill adults evaluating any pharmacological, non-pharmacological, or multi-component intervention for delirium prevention, administered in or prior to (i.e., peri-operatively) transfer to the ICU. Two authors will independently screen search results and extract data from eligible studies. Risk of bias assessments will be completed on all included studies. To inform our network meta-analysis, we will first conduct conventional pair-wise meta-analyses for primary and secondary outcomes using random-effects models. We will generate our network meta-analysis using a Bayesian framework, assuming a common heterogeneity parameter across all comparisons, and accounting for correlations in multi-arm studies. We will perform analyses using WinBUGS software. This systematic review will address the existing knowledge gap regarding best practices for delirium prevention in critically ill adults by synthesizing evidence from trials of pharmacological, non-pharmacological, and multi-component interventions administered in or prior to transfer to the ICU. Use of network meta-analysis will clarify which delirium prevention strategies are most effective in improving clinical outcomes while causing least harm. The network meta-analysis is a novel approach and will provide knowledge users and decision makers with comparisons of multiple interventions of delirium prevention strategies. PROSPERO CRD42016036313.

Systematic Review of the Indirect Effect of Pneumococcal Conjugate Vaccine Dosing Schedules on Pneumococcal Disease and Colonization

PubMed Central

2014-01-01

Background: To aid decision making for pneumococcal conjugate vaccine (PCV) use in infant national immunization programs, we summarized the indirect effects of PCV on clinical outcomes among nontargeted age groups. Methods: We systematically reviewed the English literature on infant PCV dosing schedules published from 1994 to 2010 (with ad hoc addition of 2011 articles) for outcomes on children >5 years of age and adults including vaccine-type nasopharyngeal carriage (VT-NP), vaccine-type invasive pneumococcal disease (VT-IPD) and syndromic pneumonia. Results: Of 12,980 citations reviewed, we identified 21 VT-IPD, 6 VT-NP and 9 pneumonia studies. Of these 36, 21 (58%) included 3 primary doses plus PCV or pneumococcal polysaccharide vaccine (PPV23) booster schedule (3+1 or 3+PPV23), 5 (14%) 3+0, 9 (25%) 2+1 and 1 (3%) 2+0. Most (95%) were PCV7 studies. Among observational VT-IPD studies, all schedules (2+1, 3+0 and 3+1) demonstrated reductions in incidence among young adult groups. Among syndromic pneumonia observational studies (2+1, 3+0 and 3+1), only 3+1 schedules showed significant indirect impact. Of 2 VT-NP controlled trials (3+0 and 3+1) and 3 VT-NP observational studies (2+1, 3+1 and 3+PPV23), 3+1 and 3+PPV23 schedules showed significant indirect effect. The 1 study to directly compare between schedules was a VT-NP study (2+0 vs. 2+1), which found no indirect effect on older siblings and parents of vaccinated children with either schedule. Conclusions: Indirect benefit of a 3+1 infant PCV dosing schedule has been demonstrated for VT-IPD, VT-NP and syndromic pneumonia; 2+1 and 3+0 schedules have demonstrated indirect effect only for VT-IPD. The choice of optimal infant PCV schedule is limited by data paucity on indirect effects, especially a lack of head-to-head studies and studies of PCV10 and PCV13. PMID:24336058

Interactogeneous: Disease Gene Prioritization Using Heterogeneous Networks and Full Topology Scores

PubMed Central

Gonçalves, Joana P.; Francisco, Alexandre P.; Moreau, Yves; Madeira, Sara C.

2012-01-01

Disease gene prioritization aims to suggest potential implications of genes in disease susceptibility. Often accomplished in a guilt-by-association scheme, promising candidates are sorted according to their relatedness to known disease genes. Network-based methods have been successfully exploiting this concept by capturing the interaction of genes or proteins into a score. Nonetheless, most current approaches yield at least some of the following limitations: (1) networks comprise only curated physical interactions leading to poor genome coverage and density, and bias toward a particular source; (2) scores focus on adjacencies (direct links) or the most direct paths (shortest paths) within a constrained neighborhood around the disease genes, ignoring potentially informative indirect paths; (3) global clustering is widely applied to partition the network in an unsupervised manner, attributing little importance to prior knowledge; (4) confidence weights and their contribution to edge differentiation and ranking reliability are often disregarded. We hypothesize that network-based prioritization related to local clustering on graphs and considering full topology of weighted gene association networks integrating heterogeneous sources should overcome the above challenges. We term such a strategy Interactogeneous. We conducted cross-validation tests to assess the impact of network sources, alternative path inclusion and confidence weights on the prioritization of putative genes for 29 diseases. Heat diffusion ranking proved the best prioritization method overall, increasing the gap to neighborhood and shortest paths scores mostly on single source networks. Heterogeneous associations consistently delivered superior performance over single source data across the majority of methods. Results on the contribution of confidence weights were inconclusive. Finally, the best Interactogeneous strategy, heat diffusion ranking and associations from the STRING database, was used to prioritize genes for Parkinson’s disease. This method effectively recovered known genes and uncovered interesting candidates which could be linked to pathogenic mechanisms of the disease. PMID:23185389

A Family of Algorithms for Computing Consensus about Node State from Network Data

PubMed Central

Brush, Eleanor R.; Krakauer, David C.; Flack, Jessica C.

2013-01-01

Biological and social networks are composed of heterogeneous nodes that contribute differentially to network structure and function. A number of algorithms have been developed to measure this variation. These algorithms have proven useful for applications that require assigning scores to individual nodes–from ranking websites to determining critical species in ecosystems–yet the mechanistic basis for why they produce good rankings remains poorly understood. We show that a unifying property of these algorithms is that they quantify consensus in the network about a node's state or capacity to perform a function. The algorithms capture consensus by either taking into account the number of a target node's direct connections, and, when the edges are weighted, the uniformity of its weighted in-degree distribution (breadth), or by measuring net flow into a target node (depth). Using data from communication, social, and biological networks we find that that how an algorithm measures consensus–through breadth or depth– impacts its ability to correctly score nodes. We also observe variation in sensitivity to source biases in interaction/adjacency matrices: errors arising from systematic error at the node level or direct manipulation of network connectivity by nodes. Our results indicate that the breadth algorithms, which are derived from information theory, correctly score nodes (assessed using independent data) and are robust to errors. However, in cases where nodes “form opinions” about other nodes using indirect information, like reputation, depth algorithms, like Eigenvector Centrality, are required. One caveat is that Eigenvector Centrality is not robust to error unless the network is transitive or assortative. In these cases the network structure allows the depth algorithms to effectively capture breadth as well as depth. Finally, we discuss the algorithms' cognitive and computational demands. This is an important consideration in systems in which individuals use the collective opinions of others to make decisions. PMID:23874167

Powering up with indirect reciprocity in a large-scale field experiment.

PubMed

Yoeli, Erez; Hoffman, Moshe; Rand, David G; Nowak, Martin A

2013-06-18

A defining aspect of human cooperation is the use of sophisticated indirect reciprocity. We observe others, talk about others, and act accordingly. We help those who help others, and we cooperate expecting that others will cooperate in return. Indirect reciprocity is based on reputation, which spreads by communication. A crucial aspect of indirect reciprocity is observability: reputation effects can support cooperation as long as peoples' actions can be observed by others. In evolutionary models of indirect reciprocity, natural selection favors cooperation when observability is sufficiently high. Complimenting this theoretical work are experiments where observability promotes cooperation among small groups playing games in the laboratory. Until now, however, there has been little evidence of observability's power to promote large-scale cooperation in real world settings. Here we provide such evidence using a field study involving 2413 subjects. We collaborated with a utility company to study participation in a program designed to prevent blackouts. We show that observability triples participation in this public goods game. The effect is over four times larger than offering a $25 monetary incentive, the company's previous policy. Furthermore, as predicted by indirect reciprocity, we provide evidence that reputational concerns are driving our observability effect. In sum, we show how indirect reciprocity can be harnessed to increase cooperation in a relevant, real-world public goods game.

Network Exposure and Homicide Victimization in an African American Community

PubMed Central

Wildeman, Christopher

2014-01-01

Objectives. We estimated the association of an individual’s exposure to homicide in a social network and the risk of individual homicide victimization across a high-crime African American community. Methods. Combining 5 years of homicide and police records, we analyzed a network of 3718 high-risk individuals that was created by instances of co-offending. We used logistic regression to model the odds of being a gunshot homicide victim by individual characteristics, network position, and indirect exposure to homicide. Results. Forty-one percent of all gun homicides occurred within a network component containing less than 4% of the neighborhood’s population. Network-level indicators reduced the association between individual risk factors and homicide victimization and improved the overall prediction of individual victimization. Network exposure to homicide was strongly associated with victimization: the closer one is to a homicide victim, the greater the risk of victimization. Regression models show that exposure diminished with social distance: each social tie removed from a homicide victim decreased one’s odds of being a homicide victim by 57%. Conclusions. Risk of homicide in urban areas is even more highly concentrated than previously thought. We found that most of the risk of gun violence was concentrated in networks of identifiable individuals. Understanding these networks may improve prediction of individual homicide victimization within disadvantaged communities. PMID:24228655

Network exposure and homicide victimization in an African American community.

PubMed

Papachristos, Andrew V; Wildeman, Christopher

2014-01-01

We estimated the association of an individual's exposure to homicide in a social network and the risk of individual homicide victimization across a high-crime African American community. Combining 5 years of homicide and police records, we analyzed a network of 3718 high-risk individuals that was created by instances of co-offending. We used logistic regression to model the odds of being a gunshot homicide victim by individual characteristics, network position, and indirect exposure to homicide. Forty-one percent of all gun homicides occurred within a network component containing less than 4% of the neighborhood's population. Network-level indicators reduced the association between individual risk factors and homicide victimization and improved the overall prediction of individual victimization. Network exposure to homicide was strongly associated with victimization: the closer one is to a homicide victim, the greater the risk of victimization. Regression models show that exposure diminished with social distance: each social tie removed from a homicide victim decreased one's odds of being a homicide victim by 57%. Risk of homicide in urban areas is even more highly concentrated than previously thought. We found that most of the risk of gun violence was concentrated in networks of identifiable individuals. Understanding these networks may improve prediction of individual homicide victimization within disadvantaged communities.

A Climatologically Significant Aerosol Longwave Indirect Effect in the Arctic

NASA Astrophysics Data System (ADS)

Lubin, D.; Vogelmann, A.

2006-12-01

Analysis of Atmospheric Emitted Radiance Interferometer (AERI) data from the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Program North Slope of Alaska (NSA) site confirms a pervasive first indirect effect of aerosols in low-level stratiform clouds, which are the prevailing meteorological condition throughout the Arctic. The AERI longwave emission spectra under clouds of low to moderate optical depth (<8) are sensitive to both the effective droplet radius and the liquid water path, and can be used to retrieve both quantities. When supplemented by additional NSA sensor data, these AERI retrievals reveal a longwave surface flux enhancement of 8.2 Watts per square meter under liquid water clouds subject to aerosol entrainment versus similar clouds in clean air. Of this total enhancement revealed by co-located pyrgeometer data, 3.4 Watts per square meter can be readily attributed to the first indirect effect. This observed indirect effect occurs frequently during spring, but rarely during summer. The indirect effect's manifestation in the longwave is climatologically significant given that this part of the spectrum dominates the radiation budget at high latitudes throughout most of the year. Lubin, D., and A. M. Voglemann, Nature, 439, 453-456 (2006).

Population density of North American elk: effects on plant diversity.

PubMed

Stewart, Kelley M; Bowyer, R Terry; Kie, John G; Dick, Brian L; Ruess, Roger W

2009-08-01

Large, herbivorous mammals have profound effects on ecosystem structure and function and often act as keystone species in ecosystems they inhabit. Density-dependent processes associated with population structure of large mammals may interact with ecosystem functioning to increase or decrease biodiversity, depending on the relationship of herbivore populations relative to the carrying capacity (K) of the ecosystem. We tested for indirect effects of population density of large herbivores on plant species richness and diversity in a montane ecosystem, where increased net aboveground primary productivity (NAPP) in response to low levels of herbivory has been reported. We documented a positive, linear relationship between plant-species diversity and richness with NAPP. Structural equation modeling revealed significant indirect relationships between population density of herbivores, NAPP, and species diversity. We observed an indirect effect of density-dependent processes in large, herbivorous mammals and species diversity of plants through changes in NAPP in this montane ecosystem. Changes in species diversity of plants in response to herbivory may be more indirect in ecosystems with long histories of herbivory. Those subtle or indirect effects of herbivory may have strong effects on ecosystem functioning, but may be overlooked in plant communities that are relatively resilient to herbivory.

Indirect effects of phorid fly parasitoids on the mechanisms of interspecific competition among ants.

PubMed

Morrison, Lloyd W

1999-10-01

Indirect effects, which occur when the impact of one species upon another requires the existence of an intermediary species, are apparently very common and may be of greater magnitude than direct effects. Behaviorally mediated indirect effects occur when one species affects the behavior of a second, which in turn affects how that species interacts with a third. I studied behaviorally mediated indirect effects on the mechanisms of competition in two congeneric fire ant species in the presence and absence of parasitoid phorid flies, which parasitized only one ant species. In observational and experimental field studies, the presence of native Texas phorid flies in the genus Pseudacteon decreased food retrieval by their host, Solenopsis geminata (F.), by as much as 50%. In the presence of phorid flies, many S. geminata workers assumed a stationary, curled defensive posture and did not forage. Although the phorid parasitoids had a relatively large effect on exploitative competition, there was no measurable effect on interference competition. Fierce interspecific aggression was observed between S. geminata and S. invicta Buren, and the presence of phorids had no effect on the outcome of these contests. The indirect effects of Pseudacteon parasitoids on Solenopsis fire ant resource retrieval appear to be larger than the direct effect of mortality. Some aspects of the foraging behavior of these Solenopsis species may be, in part, evolutionary adaptations to phorid parasitoid pressure. Because of the relatively large indirect effects, South American Pseudacteon phorids may be promising biocontrol agents of imported fire ants, S. invicta, in the USA. In a laboratory study, a single South American Pseudacteon female was able to significantly decrease food retrieval rates of a North American population of the imported fire ant, S. invicta.

Direct and indirect effects of copper-contaminated sediments on the functions of model freshwater ecosystems.

PubMed

Gardham, Stephanie; Chariton, Anthony A; Hose, Grant C

2015-01-01

Copper is acutely toxic to, and directly affects, primary producers and decomposers, which are key players in essential processes such as the nutrient cycle in freshwater ecosystems. Even though the indirect effects of metals (for example effects due to changes in species interactions) may be more common than direct effects, little is known about the indirect effects of copper on primary producers and decomposers. The effects of copper on phytoplankton, macrophytes, periphyton and organic matter decomposition in an outdoor lentic mesocosm facility were assessed, and links between the responses examined. Copper directly decreased macrophyte growth, subsurface organic matter decomposition, and the potential for high phytoplankton Chlorophyll a concentrations. However, periphyton cover and organic matter decomposition on the surface of the sediment were stimulated by the presence of copper. These latter responses were attributed to indirect effects, due to a reduction in grazing pressure from snails, particularly Physa acuta, in the higher copper-contaminated mesocosms. This permitted the growth of periphyton and other heterotrophs, ultimately increasing decomposition at the sediment surface. The present study demonstrates the pronounced influence indirect effects may have on ecological function, findings that may not be observed in traditional laboratory studies (which utilize single species or simplistic communities).

Individual variation in behavioural plasticity: direct and indirect effects of boldness, exploration and sociability on habituation to predators in lizards.

PubMed

Rodríguez-Prieto, Iñaki; Martín, José; Fernández-Juricic, Esteban

2011-01-22

Little is known about the factors causing variation in behavioural plasticity and the interplay between personality and plasticity. Habituation to predators is a special case of behavioural plasticity. We investigated the direct and indirect effects of boldness, exploration and sociability traits on the habituation ability of Iberian wall lizards, considering exposure and sex effects. Individual boldness was consistent across several non-habituation contexts, but it did not significantly affect habituation. Exploration had a strong direct effect on habituation, with more exploratory individuals being able to habituate faster than less exploratory ones, probably because of their ability to assess risk better. Individual variation in habituation was also affected by sociability, but this was an indirect effect mediated by exposure to the predator. Less social individuals avoided refuges with conspecific cues, increasing exposure to the predator and eventually habituation. Finally, the direct effects of sex (females habituated faster than males) were opposite to its indirect effects through exposure. We conclude that risk assessment, instead of the proactivity-reactivity gradient usually considered in the literature, can affect behavioural plasticity through complex interactions between direct and indirect effects, including exploratory behaviour, degree of exposure to the predator and sex, which represent novel mechanisms generating inter-individual variation in plasticity.

Direct and indirect responses of a freshwater food web to a potent synthetic oestrogen

PubMed Central

Kidd, Karen A.; Paterson, Michael J.; Rennie, Michael D.; Podemski, Cheryl L.; Findlay, Dave L.; Blanchfield, Paul J.; Liber, Karsten

2014-01-01

Endocrine-disrupting chemicals (EDCs) in municipal effluents directly affect the sexual development and reproductive success of fishes, but indirect effects on invertebrate prey or fish predators through reduced predation or prey availability, respectively, are unknown. At the Experimental Lakes Area in northwestern Ontario, Canada, a long-term, whole-lake experiment was conducted using a before-after-control-impact design to determine both direct and indirect effects of the synthetic oestrogen used in the birth control pill, 17α-ethynyloestradiol (EE2). Algal, microbial, zooplankton and benthic invertebrate communities showed no declines in abundance during three summers of EE2 additions (5–6 ng l−1), indicating no direct toxic effects. Recruitment of fathead minnow (Pimephales promelas) failed, leading to a near-extirpation of this species both 2 years during (young-of-year, YOY) and 2 years following (adults and YOY) EE2 additions. Body condition of male lake trout (Salvelinus namaycush) and male and female white sucker (Catostomus commersonii) declined before changes in prey abundance, suggesting direct effects of EE2 on this endpoint. Evidence of indirect effects of EE2 was also observed. Increases in zooplankton, Chaoborus, and emerging insects were observed after 2 or 3 years of EE2 additions, strongly suggesting indirect effects mediated through the reduced abundance of several small-bodied fishes. Biomass of top predator lake trout declined by 23–42% during and after EE2 additions, most probably an indirect effect from the loss of its prey species, the fathead minnow and slimy sculpin (Cottus cognatus). Our results demonstrate that small-scale studies focusing solely on direct effects are likely to underestimate the true environmental impacts of oestrogens in municipal wastewaters and provide further evidence of the value of whole-ecosystem experiments for understanding indirect effects of EDCs and other aquatic stressors. PMID:25405967

Method for evaluating multiple mediators: mediating effects of smoking and COPD on the association between the CHRNA5-A3 variant and lung cancer risk.

PubMed

Wang, Jian; Spitz, Margaret R; Amos, Christopher I; Wu, Xifeng; Wetter, David W; Cinciripini, Paul M; Shete, Sanjay

2012-01-01

A mediation model explores the direct and indirect effects between an independent variable and a dependent variable by including other variables (or mediators). Mediation analysis has recently been used to dissect the direct and indirect effects of genetic variants on complex diseases using case-control studies. However, bias could arise in the estimations of the genetic variant-mediator association because the presence or absence of the mediator in the study samples is not sampled following the principles of case-control study design. In this case, the mediation analysis using data from case-control studies might lead to biased estimates of coefficients and indirect effects. In this article, we investigated a multiple-mediation model involving a three-path mediating effect through two mediators using case-control study data. We propose an approach to correct bias in coefficients and provide accurate estimates of the specific indirect effects. Our approach can also be used when the original case-control study is frequency matched on one of the mediators. We employed bootstrapping to assess the significance of indirect effects. We conducted simulation studies to investigate the performance of the proposed approach, and showed that it provides more accurate estimates of the indirect effects as well as the percent mediated than standard regressions. We then applied this approach to study the mediating effects of both smoking and chronic obstructive pulmonary disease (COPD) on the association between the CHRNA5-A3 gene locus and lung cancer risk using data from a lung cancer case-control study. The results showed that the genetic variant influences lung cancer risk indirectly through all three different pathways. The percent of genetic association mediated was 18.3% through smoking alone, 30.2% through COPD alone, and 20.6% through the path including both smoking and COPD, and the total genetic variant-lung cancer association explained by the two mediators was 69.1%.

Alternative sensor system and MLP neural network for vehicle pedal activity estimation.

PubMed

Wefky, Ahmed M; Espinosa, Felipe; Jiménez, José A; Santiso, Enrique; Rodríguez, José M; Fernández, Alfredo J

2010-01-01

It is accepted that the activity of the vehicle pedals (i.e., throttle, brake, clutch) reflects the driver's behavior, which is at least partially related to the fuel consumption and vehicle pollutant emissions. This paper presents a solution to estimate the driver activity regardless of the type, model, and year of fabrication of the vehicle. The solution is based on an alternative sensor system (regime engine, vehicle speed, frontal inclination and linear acceleration) that reflects the activity of the pedals in an indirect way, to estimate that activity by means of a multilayer perceptron neural network with a single hidden layer.

Alternative Sensor System and MLP Neural Network for Vehicle Pedal Activity Estimation

PubMed Central

Wefky, Ahmed M.; Espinosa, Felipe; Jiménez, José A.; Santiso, Enrique; Rodríguez, José M.; Fernández, Alfredo J.

2010-01-01

It is accepted that the activity of the vehicle pedals (i.e., throttle, brake, clutch) reflects the driver’s behavior, which is at least partially related to the fuel consumption and vehicle pollutant emissions. This paper presents a solution to estimate the driver activity regardless of the type, model, and year of fabrication of the vehicle. The solution is based on an alternative sensor system (regime engine, vehicle speed, frontal inclination and linear acceleration) that reflects the activity of the pedals in an indirect way, to estimate that activity by means of a multilayer perceptron neural network with a single hidden layer. PMID:22319326

Network meta-analysis of migraine disorder treatment by NSAIDs and triptans.

PubMed

Xu, Haiyang; Han, Wei; Wang, Jinghua; Li, Mingxian

2016-12-01

Migraine is a neurological disorder resulting in large socioeconomic burden. This network meta-analysis (NMA) is designed to compare the relative efficacy and tolerability of non-steroidal anti-inflammatory agents (NSAIDs) and triptans. We conducted systematic searches in database PubMed and Embase. Treatment effectiveness was compared by synthesizing direct and indirect evidences using NMA. The surface under curve ranking area (SUCRA) was created to rank those interventions. Eletriptan and rizatriptan are superior to sumatriptan, zolmitriptan, almotriptan, ibuprofen and aspirin with respect to pain-relief. When analyzing 2 h-nausea-absence, rizatriptan has a better efficacy than sumatriptan, while other treatments indicate no distinctive difference compared with placebo. Furthermore, sumatriptan demonstrates a higher incidence of all-adverse-event compared with diclofenac-potassium, ibuprofen and almotriptan. This study suggests that eletriptan may be the most suitable therapy for migraine from a comprehensive point of view. In the meantime ibuprofen may also be a good choice for its excellent tolerability. Multi-component medication also attracts attention and may be a promising avenue for the next generation of migraine treatment.

The adoption of Firm-Hosted Online Communities: an empirical investigation into the role of service quality and social interactions

NASA Astrophysics Data System (ADS)

Corkindale, David; Ram, Jiwat; Chen, Howard

2018-02-01

Online communities are a powerful device for collaborative creativity and innovation. Developments in Web 2.0 technologies have given rise to such interactions through firm-hosted online communities (FHOCs) - firm-run online information services that also provide self-help to a community. We devise a model that seeks to explain the factors that encourage people to become members of a FHOC and test the model using structural equation modelling based on data collected from 511 users of a FHOC. The study finds that: (a) an understanding of Perceived Usefulness (PU) plays a mediating role between Behavioural Intention (BI) to adopt FHOC and Trust, as well as Interface design; b) Networking among users has an indirect effect on BI; and c) design of the Interface has a direct influence on BI. A managerial implication is that Networking plays a role in the way supplementary services, including blogs and discussion forums, are perceived. Theoretically, when service quality is decomposed into components such as core services and supplementary services, it also positively influences PU.

Linguistic analysis of large-scale medical incident reports for patient safety.

PubMed

Fujita, Katsuhide; Akiyama, Masanori; Park, Keunsik; Yamaguchi, Etsuko Nakagami; Furukawa, Hiroyuki

2012-01-01

The analysis of medical incident reports is indispensable for patient safety. The cycles between analysis of incident reports and proposals to medical staffs are a key point for improving the patient safety in the hospital. Most incident reports are composed from freely written descriptions, but an analysis of such free descriptions is not sufficient in the medical field. In this study, we aim to accumulate and reinterpret findings using structured incident information, to clarify improvements that should be made to solve the root cause of the accident, and to ensure safe medical treatment through such improvements. We employ natural language processing (NLP) and network analysis to identify effective categories of medical incident reports. Network analysis can find various relationships that are not only direct but also indirect. In addition, we compare bottom-up results obtained by NLP with existing categories based on experts' judgment. By the bottom-up analysis, the class of patient managements regarding patients' fallings and medicines in top-down analysis is created clearly. Finally, we present new perspectives on ways of improving patient safety.

Reconstructing gene regulatory networks from knock-out data using Gaussian Noise Model and Pearson Correlation Coefficient.

PubMed

Mohamed Salleh, Faridah Hani; Arif, Shereena Mohd; Zainudin, Suhaila; Firdaus-Raih, Mohd

2015-12-01

A gene regulatory network (GRN) is a large and complex network consisting of interacting elements that, over time, affect each other's state. The dynamics of complex gene regulatory processes are difficult to understand using intuitive approaches alone. To overcome this problem, we propose an algorithm for inferring the regulatory interactions from knock-out data using a Gaussian model combines with Pearson Correlation Coefficient (PCC). There are several problems relating to GRN construction that have been outlined in this paper. We demonstrated the ability of our proposed method to (1) predict the presence of regulatory interactions between genes, (2) their directionality and (3) their states (activation or suppression). The algorithm was applied to network sizes of 10 and 50 genes from DREAM3 datasets and network sizes of 10 from DREAM4 datasets. The predicted networks were evaluated based on AUROC and AUPR. We discovered that high false positive values were generated by our GRN prediction methods because the indirect regulations have been wrongly predicted as true relationships. We achieved satisfactory results as the majority of sub-networks achieved AUROC values above 0.5. Copyright © 2015 Elsevier Ltd. All rights reserved.

A Genome-Wide RNAi Screen for Modifiers of the Circadian Clock in Human Cells

PubMed Central

Zhang, Eric E.; Liu, Andrew C.; Hirota, Tsuyoshi; Miraglia, Loren J.; Welch, Genevieve; Pongsawakul, Pagkapol Y.; Liu, Xianzhong; Atwood, Ann; Huss, Jon W.; Janes, Jeff; Su, Andrew I.; Hogenesch, John B.; Kay, Steve A.

2009-01-01

Summary Two decades of research identified more than a dozen clock genes and defined a biochemical feedback mechanism of circadian oscillator function. To identify additional clock genes and modifiers, we conducted a genome-wide siRNA screen in a human cellular clock model. Knockdown of nearly a thousand genes reduced rhythm amplitude. Potent effects on period length or increased amplitude were less frequent; we found hundreds of these and confirmed them in secondary screens. Characterization of a subset of these genes demonstrated a dosage-dependent effect on oscillator function. Protein interaction network analysis showed that dozens of gene products directly or indirectly associate with known clock components. Pathway analysis revealed these genes are overrepresented for components of insulin and hedgehog signaling, the cell cycle, and the folate metabolism. Coupled with data showing many of these pathways are clock-regulated, we conclude the clock is interconnected with many aspects of cellular function. PMID:19765810

The Mpi-M Aerosol Climatology (MAC)

NASA Astrophysics Data System (ADS)

Kinne, S.

2014-12-01

Monthly gridded global data-sets for aerosol optical properties (AOD, SSA and g) and for aerosol microphysical properties (CCN and IN) offer a (less complex) alternate path to include aerosol radiative effects and aerosol impacts on cloud-microphysics in global simulations. Based on merging AERONET sun-/sky-photometer data onto background maps provided by AeroCom phase 1 modeling output and AERONET sun-/the MPI-M Aerosol Climatology (MAC) version 1 was developed and applied in IPCC simulations with ECHAM and as ancillary data-set in satellite-based global data-sets. An updated version 2 of this climatology will be presented now applying central values from the more recent AeroCom phase 2 modeling and utilizing the better global coverage of trusted sun-photometer data - including statistics from the Marine Aerosol network (MAN). Applications include spatial distributions of estimates for aerosol direct and aerosol indirect radiative effects.

Effects of semantic relatedness on recall of stimuli preceding emotional oddballs.

PubMed

Smith, Ryan M; Beversdorf, David Q

2008-07-01

Semantic and episodic memory networks function as highly interconnected systems, both relying on the hippocampal/medial temporal lobe complex (HC/MTL). Episodic memory encoding triggers the retrieval of semantic information, serving to incorporate contextual relationships between the newly acquired memory and existing semantic representations. While emotional material augments episodic memory encoding at the time of stimulus presentation, interactions between emotion and semantic memory that contribute to subsequent episodic recall are not well understood. Using a modified oddball task, we examined the modulatory effects of negative emotion on semantic interactions with episodic memory by measuring the free-recall of serially presented neutral or negative words varying in semantic relatedness. We found increased free-recall for words related to and preceding emotionally negative oddballs, suggesting that negative emotion can indirectly facilitate episodic free-recall by enhancing semantic contributions during encoding. Our findings demonstrate the ability of emotion and semantic memory to interact to mutually enhance free-recall.

Electronic properties of 8 - Pmmn borophene

DOE PAGES

Lopez-Bezanilla, Alejandro; Littlewood, Peter B.

2016-06-15

First-principles calculations on monolayer 8-Pmmn borophene are reported to reveal unprecedented electronic properties in a two-dimensional material. Based on a Born effective charge analysis, 8-Pmmn borophene is the first single-element-based monolayered material exhibiting two sublattices with substantial ionic features. We observed Dirac cones are actually formed by the p(z) orbitals of one of the inequivalent sublattices composed of uniquely four atoms, yielding an underlying hexagonal network topologically equivalent to distorted graphene. One significant physical outcome of this effect includes the possibility of converting metallic 8-Pmmn borophene into an indirect band gap semiconductor by means of external shear stress. Furthermore, themore » stability of the strained structures are supported by a phonon frequency analysis. The Dirac cones are sensitive to the formation of vacancies only in the inequivalent sublattice electronically active at the Fermi level.« less

On the Inference of Functional Circadian Networks Using Granger Causality

PubMed Central

Pourzanjani, Arya; Herzog, Erik D.; Petzold, Linda R.

2015-01-01

Being able to infer one way direct connections in an oscillatory network such as the suprachiastmatic nucleus (SCN) of the mammalian brain using time series data is difficult but crucial to understanding network dynamics. Although techniques have been developed for inferring networks from time series data, there have been no attempts to adapt these techniques to infer directional connections in oscillatory time series, while accurately distinguishing between direct and indirect connections. In this paper an adaptation of Granger Causality is proposed that allows for inference of circadian networks and oscillatory networks in general called Adaptive Frequency Granger Causality (AFGC). Additionally, an extension of this method is proposed to infer networks with large numbers of cells called LASSO AFGC. The method was validated using simulated data from several different networks. For the smaller networks the method was able to identify all one way direct connections without identifying connections that were not present. For larger networks of up to twenty cells the method shows excellent performance in identifying true and false connections; this is quantified by an area-under-the-curve (AUC) 96.88%. We note that this method like other Granger Causality-based methods, is based on the detection of high frequency signals propagating between cell traces. Thus it requires a relatively high sampling rate and a network that can propagate high frequency signals. PMID:26413748

Gender Differences in Posttraumatic Stress Symptoms after a Terrorist Attack: A Network Approach.

PubMed

Birkeland, Marianne S; Blix, Ines; Solberg, Øivind; Heir, Trond

2017-01-01

Background: Posttraumatic stress symptoms are more prevalent in women than in men. To improve our understanding of gender differences in PTSD, detailed knowledge about the underlying symptom networks and gender specific symptom profiles is needed. Objective: We aimed to describe the gender differences in levels of individual posttraumatic stress symptoms after a terrorist attack, as well as identify possible gender differences in associations between posttraumatic stress symptoms. Method: This study used survey data from ministerial employees directly ( n = 190) and indirectly ( n = 1,615) exposed to the 2011 Oslo bombing. Data was collected approximately 10 months after the event. In order to investigate gender differences in levels of symptoms, we used bootstrapped means and standard deviations. Network analyses were conducted to identify gender differences in the associations between posttraumatic stress symptoms. Results: Women reported higher levels of all symptoms, and the strongest effect sizes were found for symptoms of re-experiencing, and anxious and dysphoric arousal. Among individuals with considerable levels of posttraumatic stress symptoms, women reported higher levels of physiological cue activity and exaggerated startle response. No significant gender differences in the networks of posttraumatic stress were found. Conclusions: The present results find no indication that the gender difference in prevalence of PTSD can be explained by differences in associations between symptoms. In order to determine if this finding can be applied to other participants and circumstances, future studies should seek to replicate this study in both community and clinical samples.

Untangling Basal Ganglia Network Dynamics and Function: Role of Dopamine Depletion and Inhibition Investigated in a Spiking Network Model.

PubMed

Lindahl, Mikael; Hellgren Kotaleski, Jeanette

2016-01-01

The basal ganglia are a crucial brain system for behavioral selection, and their function is disturbed in Parkinson's disease (PD), where neurons exhibit inappropriate synchronization and oscillations. We present a spiking neural model of basal ganglia including plausible details on synaptic dynamics, connectivity patterns, neuron behavior, and dopamine effects. Recordings of neuronal activity in the subthalamic nucleus and Type A (TA; arkypallidal) and Type I (TI; prototypical) neurons in globus pallidus externa were used to validate the model. Simulation experiments predict that both local inhibition in striatum and the existence of an indirect pathway are important for basal ganglia to function properly over a large range of cortical drives. The dopamine depletion-induced increase of AMPA efficacy in corticostriatal synapses to medium spiny neurons (MSNs) with dopamine receptor D2 synapses (CTX-MSN D2) and the reduction of MSN lateral connectivity (MSN-MSN) were found to contribute significantly to the enhanced synchrony and oscillations seen in PD. Additionally, reversing the dopamine depletion-induced changes to CTX-MSN D1, CTX-MSN D2, TA-MSN, and MSN-MSN couplings could improve or restore basal ganglia action selection ability. In summary, we found multiple changes of parameters for synaptic efficacy and neural excitability that could improve action selection ability and at the same time reduce oscillations. Identification of such targets could potentially generate ideas for treatments of PD and increase our understanding of the relation between network dynamics and network function.

Mapping Cellular Polarity Networks Using Mass Spectrometry-based Strategies.

PubMed

Daulat, Avais M; Puvirajesinghe, Tania M; Camoin, Luc; Borg, Jean-Paul

2018-05-18

Cell polarity is a vital biological process involved in the building, maintenance and normal functioning of tissues in invertebrates and vertebrates. Unsurprisingly, molecular defects affecting polarity organization and functions have a strong impact on tissue homeostasis, embryonic development and adult life, and may directly or indirectly lead to diseases. Genetic studies have demonstrated the causative effect of several polarity genes in diseases; however, much remains to be clarified before a comprehensive view of the molecular organization and regulation of the protein networks associated with polarity proteins is obtained. This challenge can be approached head-on using proteomics to identify protein complexes involved in cell polarity and their modifications in a spatio-temporal manner. We review the fundamental basics of mass spectrometry techniques and provide an in-depth analysis of how mass spectrometry has been instrumental in understanding the complex and dynamic nature of some cell polarity networks at the tissue (apico-basal and planar cell polarities) and cellular (cell migration, ciliogenesis) levels, with the fine dissection of the interconnections between prototypic cell polarity proteins and signal transduction cascades in normal and pathological situations. This review primarily focuses on epithelial structures which are the fundamental building blocks for most metazoan tissues, used as the archetypal model to study cellular polarity. This field offers broad perspectives thanks to the ever-increasing sensitivity of mass spectrometry and its use in combination with recently developed molecular strategies able to probe in situ proteomic networks. Copyright © 2018 Elsevier Ltd. All rights reserved.

Gender Differences in Posttraumatic Stress Symptoms after a Terrorist Attack: A Network Approach

PubMed Central

Birkeland, Marianne S.; Blix, Ines; Solberg, Øivind; Heir, Trond

2017-01-01

Background: Posttraumatic stress symptoms are more prevalent in women than in men. To improve our understanding of gender differences in PTSD, detailed knowledge about the underlying symptom networks and gender specific symptom profiles is needed. Objective: We aimed to describe the gender differences in levels of individual posttraumatic stress symptoms after a terrorist attack, as well as identify possible gender differences in associations between posttraumatic stress symptoms. Method: This study used survey data from ministerial employees directly (n = 190) and indirectly (n = 1,615) exposed to the 2011 Oslo bombing. Data was collected approximately 10 months after the event. In order to investigate gender differences in levels of symptoms, we used bootstrapped means and standard deviations. Network analyses were conducted to identify gender differences in the associations between posttraumatic stress symptoms. Results: Women reported higher levels of all symptoms, and the strongest effect sizes were found for symptoms of re-experiencing, and anxious and dysphoric arousal. Among individuals with considerable levels of posttraumatic stress symptoms, women reported higher levels of physiological cue activity and exaggerated startle response. No significant gender differences in the networks of posttraumatic stress were found. Conclusions: The present results find no indication that the gender difference in prevalence of PTSD can be explained by differences in associations between symptoms. In order to determine if this finding can be applied to other participants and circumstances, future studies should seek to replicate this study in both community and clinical samples. PMID:29250014

A novel enteric neuron-glia coculture system reveals the role of glia in neuronal development.

PubMed

Le Berre-Scoul, Catherine; Chevalier, Julien; Oleynikova, Elena; Cossais, François; Talon, Sophie; Neunlist, Michel; Boudin, Hélène

2017-01-15

Unlike astrocytes in the brain, the potential role of enteric glial cells (EGCs) in the formation of the enteric neuronal circuit is currently unknown. To examine the role of EGCs in the formation of the neuronal network, we developed a novel neuron-enriched culture model from embryonic rat intestine grown in indirect coculture with EGCs. We found that EGCs shape axonal complexity and synapse density in enteric neurons, through purinergic- and glial cell line-derived neurotrophic factor-dependent pathways. Using a novel and valuable culture model to study enteric neuron-glia interactions, our study identified EGCs as a key cellular actor regulating neuronal network maturation. In the nervous system, the formation of neuronal circuitry results from a complex and coordinated action of intrinsic and extrinsic factors. In the CNS, extrinsic mediators derived from astrocytes have been shown to play a key role in neuronal maturation, including dendritic shaping, axon guidance and synaptogenesis. In the enteric nervous system (ENS), the potential role of enteric glial cells (EGCs) in the maturation of developing enteric neuronal circuit is currently unknown. A major obstacle in addressing this question is the difficulty in obtaining a valuable experimental model in which enteric neurons could be isolated and maintained without EGCs. We adapted a cell culture method previously developed for CNS neurons to establish a neuron-enriched primary culture from embryonic rat intestine which was cultured in indirect coculture with EGCs. We demonstrated that enteric neurons grown in such conditions showed several structural, phenotypic and functional hallmarks of proper development and maturation. However, when neurons were grown without EGCs, the complexity of the axonal arbour and the density of synapses were markedly reduced, suggesting that glial-derived factors contribute strongly to the formation of the neuronal circuitry. We found that these effects played by EGCs were mediated in part through purinergic P2Y 1 receptor- and glial cell line-derived neurotrophic factor-dependent pathways. Using a novel and valuable culture model to study enteric neuron-glia interactions, our study identified EGCs as a key cellular actor required for neuronal network maturation. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

A novel enteric neuron–glia coculture system reveals the role of glia in neuronal development

PubMed Central

Le Berre‐Scoul, Catherine; Chevalier, Julien; Oleynikova, Elena; Cossais, François; Talon, Sophie; Neunlist, Michel

2016-01-01

Key points Unlike astrocytes in the brain, the potential role of enteric glial cells (EGCs) in the formation of the enteric neuronal circuit is currently unknown.To examine the role of EGCs in the formation of the neuronal network, we developed a novel neuron‐enriched culture model from embryonic rat intestine grown in indirect coculture with EGCs.We found that EGCs shape axonal complexity and synapse density in enteric neurons, through purinergic‐ and glial cell line‐derived neurotrophic factor‐dependent pathways.Using a novel and valuable culture model to study enteric neuron–glia interactions, our study identified EGCs as a key cellular actor regulating neuronal network maturation. Abstract In the nervous system, the formation of neuronal circuitry results from a complex and coordinated action of intrinsic and extrinsic factors. In the CNS, extrinsic mediators derived from astrocytes have been shown to play a key role in neuronal maturation, including dendritic shaping, axon guidance and synaptogenesis. In the enteric nervous system (ENS), the potential role of enteric glial cells (EGCs) in the maturation of developing enteric neuronal circuit is currently unknown. A major obstacle in addressing this question is the difficulty in obtaining a valuable experimental model in which enteric neurons could be isolated and maintained without EGCs. We adapted a cell culture method previously developed for CNS neurons to establish a neuron‐enriched primary culture from embryonic rat intestine which was cultured in indirect coculture with EGCs. We demonstrated that enteric neurons grown in such conditions showed several structural, phenotypic and functional hallmarks of proper development and maturation. However, when neurons were grown without EGCs, the complexity of the axonal arbour and the density of synapses were markedly reduced, suggesting that glial‐derived factors contribute strongly to the formation of the neuronal circuitry. We found that these effects played by EGCs were mediated in part through purinergic P2Y1 receptor‐ and glial cell line‐derived neurotrophic factor‐dependent pathways. Using a novel and valuable culture model to study enteric neuron–glia interactions, our study identified EGCs as a key cellular actor required for neuronal network maturation. PMID:27436013

Rosiglitazone and Fenofibrate Additive Effects on Lipids

DTIC Science & Technology

2011-10-01

Metabolic effects of trogiltazone on fructose-induced insulin resistance in the rat,” Diabetes, vol. 43, pp. 1435–1439, 1995. [3] T. P. Ciaraldi...re- mains unclear. It is possible that these agents indirectly alter plasma lipid and lipoprotein levels indirectly by improving insulin sensitivity...induced by TZDs remains unclear. It is possible that these agents indi- rectly alter plasma lipid and lipoprotein levels indirectly by improving insulin

Decadal trends in marine reserves reveal differential rates of change in direct and indirect effects

USGS Publications Warehouse

Babcock, R.C.; Shears, N.T.; Alcala, A.C.; Barrett, N.S.; Edgar, G.J.; Lafferty, K.D.; McClanahan, T.R.; Russ, G.R.

2010-01-01

Decadal-scale observations of marine reserves suggest that indirect effects on taxa that occur through cascading trophic interactions take longer to develop than direct effects on target species. Combining and analyzing a unique set of long-term time series of ecologic data in and out of fisheries closures from disparate regions, we found that the time to initial detection of direct effects on target species (+ or -SE) was 5.13 + or - 1.9 years, whereas initial detection of indirect effects on other taxa, which were often trait mediated, took significantly longer (13.1 + or - 2.0 years). Most target species showed initial direct effects, but their trajectories over time were highly variable. Many target species continued to increase, some leveled off, and others decreased. Decreases were due to natural fluctuations, fishing impacts from outside reserves, or indirect effects from target species at higher trophic levels. The average duration of stable periods for direct effects was 6.2 + or - 1.2 years, even in studies of more than 15 years. For indirect effects, stable periods averaged 9.1 + or - 1.6 years, although this was not significantly different from direct effects. Populations of directly targeted species were more stable in reserves than in fished areas, suggesting increased ecologic resilience. This is an important benefit of marine reserves with respect to their function as a tool for conservation and restoration.

Decadal trends in marine reserves reveal differential rates of change in direct and indirect effects.

PubMed

Babcock, R C; Shears, N T; Alcala, A C; Barrett, N S; Edgar, G J; Lafferty, K D; McClanahan, T R; Russ, G R

2010-10-26

Decadal-scale observations of marine reserves suggest that indirect effects on taxa that occur through cascading trophic interactions take longer to develop than direct effects on target species. Combining and analyzing a unique set of long-term time series of ecologic data in and out of fisheries closures from disparate regions, we found that the time to initial detection of direct effects on target species (±SE) was 5.13 ± 1.9 years, whereas initial detection of indirect effects on other taxa, which were often trait mediated, took significantly longer (13.1 ± 2.0 years). Most target species showed initial direct effects, but their trajectories over time were highly variable. Many target species continued to increase, some leveled off, and others decreased. Decreases were due to natural fluctuations, fishing impacts from outside reserves, or indirect effects from target species at higher trophic levels. The average duration of stable periods for direct effects was 6.2 ± 1.2 years, even in studies of more than 15 years. For indirect effects, stable periods averaged 9.1 ± 1.6 years, although this was not significantly different from direct effects. Populations of directly targeted species were more stable in reserves than in fished areas, suggesting increased ecologic resilience. This is an important benefit of marine reserves with respect to their function as a tool for conservation and restoration.

Positive and negative feedback loops in nutrient phytoplankton interactions related to climate dynamics factors in a shallow temperate estuary (Vistula Lagoon, southern Baltic)

NASA Astrophysics Data System (ADS)

Kruk, Marek; Kobos, Justyna; Nawrocka, Lidia; Parszuto, Katarzyna

2018-04-01

This study aims to demonstrate that factors associated with climate dynamics, such as temperature and wind, affect the ecosystem of the shallow Vistula Lagoon in the southern Baltic and cause nutrient forms phytoplankton interactions: the growth of biomass and constraints of it. This occurs through a network of direct and indirect relationships between environmental and phytoplankton factors, including interactions of positive and negative feedback loops. Path analysis supported by structural equation modeling (SEM) was used to test hypotheses regarding the impact of climate factors on algal assemblages. Increased phytoplankton biomass was affected directly by water temperature and salinity, while the wind speed effect was indirect as it resulted in increased concentrations of suspended solids (SS) in the water column. Simultaneously, the concentration of SS in the water was positively correlated with particulate organic carbon (POC), particulate nitrogen (PN), and particulate phosphorus (PP), and was negatively correlated with the total nitrogen to phosphorus (N:P) ratio. Particulate forms of C, N, and phosphorus (P), concentrations of soluble reactive phosphorus (SRP) and nitrate and nitrite nitrogen (NO3-N + NO2-N), and ratios of the total N:P and DIN:SRP, all indirectly effected Cyanobacteria C concentrations. These processes influence other phytoplankton groups (Chlorophyta, Bacillariophyceae and the picophytoplankton fraction). Increased levels of SRP associated with organic matter (POC), which stemmed from reduced DIN:SRP ratios, contributed to increased Cyanoprokaryota and picophytoplankton C concentrations, which created a positive feedback loop. However, a simultaneous reduction in the total N:P ratio could have inhibited increases in the biomass of these assemblages by limiting N, which likely formed a negative feedback loop. The study indicates that the nutrients-phytoplankton feedback loop phenomenon can intensify eutrophication in a temperate lagoon, including increases of the biomass of Cyanobacteria and picophytoplankton. However, it can also constrain this increase.

Direct and indirect effects of exercise on posttraumatic stress disorder symptoms: A longitudinal study.

PubMed

Whitworth, James W; Craft, Lynette L; Dunsiger, Shira I; Ciccolo, Joseph T

2017-11-01

Emerging evidence suggests that exercise may have beneficial effects on posttraumatic stress disorder (PTSD), and that this relationship may be indirectly affected by sleep, pain, and alcohol/substance use. The present study examined the longitudinal direct and indirect effects of exercise on PTSD symptoms. A national sample of 182 individuals, screening positive for PTSD, completed online assessments of PTSD symptoms, exercise behavior, psychological distress, sleep quality, and alcohol/substance use at baseline and three-month follow-up. There were direct effects of strenuous intensity exercise on avoidance/numbing (b=-2.18, SE=1.12, p=0.05) and hyperarousal symptoms (b=-1.87, SE=0.82, p=0.03); and direct effects of total exercise on avoidance/numbing symptoms (b=-1.76, SE=0.94, p=0.05). Strenuous intensity exercise was indirectly associated with total PTSD symptoms (ab=-2.53, 95% CI: -5.72 to -0.38), avoidance/numbing (ab=-0.99, 95% CI: -2.43 to -0.05), and hyperarousal symptoms (ab=-0.78, 95% CI: -1.88 to -0.07) through sleep, while total exercise was indirectly associated with total PTSD symptoms through alcohol use (ab=0.32, 95% CI: 0.18-1.42). Findings suggest that exercise has a complex, longitudinal, and beneficial association with PTSD symptoms. Future studies should continue to examine this relationship and any direct and indirect effects exercise may have on PTSD and its related conditions. Copyright © 2017 Elsevier Inc. All rights reserved.

Aerosol Indirect Effects on Cirrus Clouds in Global Aerosol-Climate Models

NASA Astrophysics Data System (ADS)

Liu, X.; Zhang, K.; Wang, Y.; Neubauer, D.; Lohmann, U.; Ferrachat, S.; Zhou, C.; Penner, J.; Barahona, D.; Shi, X.

2015-12-01

Cirrus clouds play an important role in regulating the Earth's radiative budget and water vapor distribution in the upper troposphere. Aerosols can act as solution droplets or ice nuclei that promote ice nucleation in cirrus clouds. Anthropogenic emissions from fossil fuel and biomass burning activities have substantially perturbed and enhanced concentrations of aerosol particles in the atmosphere. Global aerosol-climate models (GCMs) have now been used to quantify the radiative forcing and effects of aerosols on cirrus clouds (IPCC AR5). However, the estimate uncertainty is very large due to the different representation of ice cloud formation and evolution processes in GCMs. In addition, large discrepancies have been found between model simulations in terms of the spatial distribution of ice-nucleating aerosols, relative humidity, and temperature fluctuations, which contribute to different estimates of the aerosol indirect effect through cirrus clouds. In this presentation, four GCMs with the start-of-the art representations of cloud microphysics and aerosol-cloud interactions are used to estimate the aerosol indirect effects on cirrus clouds and to identify the causes of the discrepancies. The estimated global and annual mean anthropogenic aerosol indirect effect through cirrus clouds ranges from 0.1 W m-2 to 0.3 W m-2 in terms of the top-of-the-atmosphere (TOA) net radiation flux, and 0.5-0.6 W m-2 for the TOA longwave flux. Despite the good agreement on global mean, large discrepancies are found at the regional scale. The physics behind the aerosol indirect effect is dramatically different. Our analysis suggests that burden of ice-nucleating aerosols in the upper troposphere, ice nucleation frequency, and relative role of ice formation processes (i.e., homogeneous versus heterogeneous nucleation) play key roles in determining the characteristics of the simulated aerosol indirect effects. In addition to the indirect effect estimate, we also use field campaign measurements and satellite retrievals to evaluate the simulated micro- and macro- physical properties of ice clouds in the four GCMs.

[Economic rehabilitation management among patients with chronic low back pain].

PubMed

Seitz, R; Schweikert, B; Jacobi, E; Tschirdewahn, B; Leidl, R

2001-12-01

Back pain causes high costs to society. In Germany, these amount to an estimated total of 5 billion euro of direct costs per year and 13 billion euro of indirect costs, the latter being caused by incapacity to work. The purpose of this study is to develop a concept for economic rehabilitation management. This concept is based on the managed care approach and aims at improving efficiency of care. The concept development consists of a theoretical and an empirical part. The method of the theoretical part is based on a systematic literature review on managed care (not included in this article), health systems research and the analysis of economic incentives. For the empirical investigation, long term effects and costs were calculated. For the evaluation of effects, we psychometrically tested and used the EuroQol (EQ-5D) as a measure of health-related quality of life (HRQL). The calculation of costs (both direct and indirect) is based on routine data of payers, a cost diary and the internal cost accounting systems of rehabilitation clinics. We statistically analysed the cost distribution and identified predictors of the management targets (e.g., costs of care) by means of regression analyses. The market-driven managed care approach is based on three tools: (1) a primary care system with case management and gatekeeping, (2) direct influence on providers by utilisation review and setting guidelines, and (3) indirect influence by setting supply-side economic incentives via the remuneration mode. The third managed care tool is most important when managing the rehabilitation of working age patients with chronic low back pain from an economic point of view. This concept consists of three components: (1) a case-based budget for direct costs; this is a prospective remuneration mode for an integrated primary care network including a rehabilitation facility, (2) retrospective bonus payments which are related to savings of indirect costs, and (3) retrospective bonus payments which are related to the effectiveness of rehabilitation, i.e. gains in HRQL. Common features of the three management components are a long-term perspective (e.g., from admission to a rehabilitation clinic until six months after discharge) and risk-adjustment of the three management targets (i.e., direct and indirect costs and gains in HRQL) in order to avoid selection and to limit the financial risk for providers. The EuroQol instrument shows acceptable psychometric properties in the rehabilitation setting for back pain patients. This instrument may yield two kinds of preference-based index values, one reflecting the preferences of the general population and one those of the patient. The Pearson correlation of these two approaches is fair, but there is a systematic difference. Empirical investigation shows that the distribution of both direct and indirect costs is skewed to the right. Statistically relevant predictors of the management targets are incapacity to work and HRQL at admission. Economic rehabilitation management might help to save money and to improve health outcomes, thus increasing the efficiency of care. The results of our empirical studies show the feasibility of tools for the economic management of rehabilitation. Risk adjustment of the management components is of paramount importance.

The Effect of Flemish Eco-Schools on Student Environmental Knowledge, Attitudes, and Affect

ERIC Educational Resources Information Center

Boeve-de Pauw, Jelle; Van Petegem, Peter

2011-01-01

Eco-schools aim to improve the environment through direct and indirect effects. Direct effects are those that result from the implementation of an environmental management system. Indirect effects are educational gains. The current study examines the effectiveness of eco-schools concerning three student outcomes: (1) environmental knowledge, (2)…

Indirection and computer security.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berg, Michael J.

2011-09-01

The discipline of computer science is built on indirection. David Wheeler famously said, 'All problems in computer science can be solved by another layer of indirection. But that usually will create another problem'. We propose that every computer security vulnerability is yet another problem created by the indirections in system designs and that focusing on the indirections involved is a better way to design, evaluate, and compare security solutions. We are not proposing that indirection be avoided when solving problems, but that understanding the relationships between indirections and vulnerabilities is key to securing computer systems. Using this perspective, we analyzemore » common vulnerabilities that plague our computer systems, consider the effectiveness of currently available security solutions, and propose several new security solutions.« less

Comparative Effectiveness of Pharmacological Interventions for Severe Alcoholic Hepatitis: A Systematic Review and Network Meta-analysis.

PubMed

Singh, Siddharth; Murad, Mohammad Hassan; Chandar, Apoorva K; Bongiorno, Connie M; Singal, Ashwani K; Atkinson, Stephen R; Thursz, Mark R; Loomba, Rohit; Shah, Vijay H

2015-10-01

Severe alcoholic hepatitis (AH) has high mortality. We assessed the comparative effectiveness of pharmacological interventions for severe AH, through a network meta-analysis combining direct and indirect treatment comparisons. We conducted a systematic literature review, through February 2015, for randomized controlled trials of adults with severe AH (discriminant function ≥32 and/or hepatic encephalopathy) that compared the efficacy of active pharmacologic interventions (corticosteroids, pentoxifylline, and N-acetylcysteine [NAC], alone or in combination) with each other or placebo, in reducing short-term mortality (primary outcome) and medium-term mortality, acute kidney injury, and/or infections (secondary outcomes). We performed direct and Bayesian network meta-analysis for all treatments, and used Grading of Recommendations Assessment, Development and Evaluation criteria to appraise quality of evidence. We included 22 randomized controlled trials (2621 patients) comparing 5 different interventions. In a direct meta-analysis, only corticosteroids decreased risk of short-term mortality. In a network meta-analysis, moderate quality evidence supported the use of corticosteroids alone (relative risk [RR], 0.54; 95% credible interval [CrI], 0.39-0.73) or in combination with pentoxifylline (RR, 0.53; 95% CrI, 0.36-0.78) or NAC (RR, 0.15; 95% CI, 0.05-0.39), to reduce short-term mortality; low quality evidence showed that pentoxifylline also decreased short-term mortality (RR, 0.70; 95% CrI, 0.50-0.97). The addition of NAC, but not pentoxifylline, to corticosteroids may be superior to corticosteroids alone for reducing short-term mortality. No treatment was effective in reducing medium-term mortality. Imprecise estimates and the small number of direct trials lowered the confidence in several comparisons. In patients with severe AH, pentoxifylline and corticosteroids (alone and in combination with pentoxifylline or NAC) can reduce short-term mortality. No treatment decreases risk of medium-term mortality. Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved.

Direct and Indirect Messages African American Women Receive from Their Familial Networks about Intimate Relationships and Sex: The Intersecting Influence of Race, Gender, and Class

ERIC Educational Resources Information Center

Grange, Christina M.; Brubaker, Sarah Jane; Corneille, Maya A.

2011-01-01

This qualitative study examined the sexual socialization experienced by emerging adult, African American women, ages 18 to 26 years, who received services at a sexually transmitted infection clinic. Data obtained from in-depth interviews revealed that women received information about sex and relationships from three primary sources: women of the…

The relationships among Muslim Uyghur and Kazakh disabled elders' life satisfaction, activity of daily living, and informal family caregiver's burden, depression, and life satisfaction in far western China: A structural equation model.

PubMed

Wang, Wen Ting; He, Bin; Wang, Yu Huan; Wang, Mei Yan; Chen, Xue Feng; Wu, Fu Chen; Yang, Xue

2017-04-01

1 Hypothesis Disabled elders' activities of daily living, caregiver burden, caregiver depression, and caregivers' life satisfaction are significantly related to the life satisfaction of elderly people with disability. 2 Hypothesis There are direct and indirect effects between the life satisfaction of elders, disabled elders' activities of daily living, and family caregivers' factors. This study explored the interrelationships of disabled elders' life satisfaction and activities of daily living, caregivers' factors (burden, depression, and life satisfaction) through a structural equation model. In total, 621 dyads of disabled elders and informal family caregivers completed questionnaires during face-to-face interviews in Xinjiang Uyghur Autonomous Region from September 2013 to January 2014. Activity of daily living exerted a direct effect on life satisfaction of disabled elders and 30.4% indirect effect through caregivers' factors. Caregiver burden had a 60.0% direct effect on life satisfaction of disabled elders and a 40.0% indirect effect through the caregiver depression. Caregiver depression showed 76% direct effect on life satisfaction of disabled elders and 24% indirect effect through caregivers' life satisfaction. Direct relationships between activity of daily living and caregiver burden, caregiver burden and caregiver depression, and caregiver depression and caregivers' life satisfaction were observed. Activity of daily living had a 91.3% indirect effect on caregiver depression mediated by caregiver burden; caregiver burden had a 40.0% indirect effect on caregivers' life satisfaction mediated by caregiver depression. Results provide useful information for nurses and policymakers and shed light on the need to consider caregivers' factors in improving care recipients' life satisfaction. © 2017 John Wiley & Sons Australia, Ltd.

[Environmental pollutants as adjuvant factors of immune system derived diseases].

PubMed

Lehmann, Irina

2017-06-01

The main task of the immune system is to protect the body against invading pathogens. To be able to do so, immune cells must be able to recognize and combat exogenous challenges and at the same time tolerate body-borne structures. A complex regulatory network controls the sensitive balance between defense and tolerance. Perturbation of this network ultimately leads to the development of chronic inflammation, such as allergies, autoimmune reactions, and infections, because the immune system is no longer able to efficiently eliminate invading pathogens. Environmental pollutants can cause such perturbations by affecting the function of immune cells in such a way that they would react hypersensitively against allergens and the body's own structures, respectively, or that they would be no longer able to adequately combat pathogens. This indirect effect is also known as adjuvant effect. For pesticides, heavy metals, wood preservatives, or volatile organic compounds such adjuvant effects are well known. Examples of the mechanism by which environmental toxins contribute to chronic inflammatory diseases are manifold and will be discussed along asthma and allergies.While the immune system of healthy adults is typically well able to distinguish between foreign and endogenous substances even under adverse environmental conditions, that of children would react much more sensible upon comparable environmental challenges. To prevent priming for diseases by environmental cues during that highly sensitive period of early childhood children are to be particularly protected.

Entrainment, Drizzle, and the Indirect Effect in Stratiform Clouds

NASA Technical Reports Server (NTRS)

Ackerman, Andrew

2005-01-01

Activation of some fraction of increased concentrations of sub-micron soluble aerosol particles lead to enhanced cloud droplet concentrations and hence smaller droplets, increasing their total cross sectional area and thus reflecting solar radiation more efficiently (the Twomey, or first indirect, effect). However, because of competition during condensational growth, droplet distributions tend to broaden as numbers increase, reducing the sensitivity of cloud albedo to droplet concentration on the order of 10%. Also, smaller droplets less effectively produce drizzle through collisions and coalescence, and it is widely expected (and found in large-scale models) that decreased precipitation leads to clouds with more cloud water on average (the so-called cloud lifetime, or second indirect, effect). Much of the uncertainty regarding the overall indirect aerosol effect stems from inadequate understanding of such changes in cloud water. Detailed simulations based on FIRE-I, ASTEX, and DYCOMS-II conditions show that suppression of precipitation from increased droplet concentrations leads to increased cloud water only when sufficient precipitation reaches the surface, a condition favored when the overlying air is-humid or droplet concentrations are very low. Otherwise, aerosol induced suppression of precipitation enhances entrainment of overlying dry air, thereby reducing cloud water and diminishing the indirect climate forcing.

Diagnostics for generalized linear hierarchical models in network meta-analysis.

PubMed

Zhao, Hong; Hodges, James S; Carlin, Bradley P

2017-09-01

Network meta-analysis (NMA) combines direct and indirect evidence comparing more than 2 treatments. Inconsistency arises when these 2 information sources differ. Previous work focuses on inconsistency detection, but little has been done on how to proceed after identifying inconsistency. The key issue is whether inconsistency changes an NMA's substantive conclusions. In this paper, we examine such discrepancies from a diagnostic point of view. Our methods seek to detect influential and outlying observations in NMA at a trial-by-arm level. These observations may have a large effect on the parameter estimates in NMA, or they may deviate markedly from other observations. We develop formal diagnostics for a Bayesian hierarchical model to check the effect of deleting any observation. Diagnostics are specified for generalized linear hierarchical NMA models and investigated for both published and simulated datasets. Results from our example dataset using either contrast- or arm-based models and from the simulated datasets indicate that the sources of inconsistency in NMA tend not to be influential, though results from the example dataset suggest that they are likely to be outliers. This mimics a familiar result from linear model theory, in which outliers with low leverage are not influential. Future extensions include incorporating baseline covariates and individual-level patient data. Copyright © 2017 John Wiley & Sons, Ltd.

Resting state functional MRI in Parkinson's disease: the impact of deep brain stimulation on 'effective' connectivity.

PubMed

Kahan, Joshua; Urner, Maren; Moran, Rosalyn; Flandin, Guillaume; Marreiros, Andre; Mancini, Laura; White, Mark; Thornton, John; Yousry, Tarek; Zrinzo, Ludvic; Hariz, Marwan; Limousin, Patricia; Friston, Karl; Foltynie, Tom

2014-04-01

Depleted of dopamine, the dynamics of the parkinsonian brain impact on both 'action' and 'resting' motor behaviour. Deep brain stimulation has become an established means of managing these symptoms, although its mechanisms of action remain unclear. Non-invasive characterizations of induced brain responses, and the effective connectivity underlying them, generally appeals to dynamic causal modelling of neuroimaging data. When the brain is at rest, however, this sort of characterization has been limited to correlations (functional connectivity). In this work, we model the 'effective' connectivity underlying low frequency blood oxygen level-dependent fluctuations in the resting Parkinsonian motor network-disclosing the distributed effects of deep brain stimulation on cortico-subcortical connections. Specifically, we show that subthalamic nucleus deep brain stimulation modulates all the major components of the motor cortico-striato-thalamo-cortical loop, including the cortico-striatal, thalamo-cortical, direct and indirect basal ganglia pathways, and the hyperdirect subthalamic nucleus projections. The strength of effective subthalamic nucleus afferents and efferents were reduced by stimulation, whereas cortico-striatal, thalamo-cortical and direct pathways were strengthened. Remarkably, regression analysis revealed that the hyperdirect, direct, and basal ganglia afferents to the subthalamic nucleus predicted clinical status and therapeutic response to deep brain stimulation; however, suppression of the sensitivity of the subthalamic nucleus to its hyperdirect afferents by deep brain stimulation may subvert the clinical efficacy of deep brain stimulation. Our findings highlight the distributed effects of stimulation on the resting motor network and provide a framework for analysing effective connectivity in resting state functional MRI with strong a priori hypotheses.

Clustering in large networks does not promote upstream reciprocity.

PubMed

Masuda, Naoki

2011-01-01

Upstream reciprocity (also called generalized reciprocity) is a putative mechanism for cooperation in social dilemma situations with which players help others when they are helped by somebody else. It is a type of indirect reciprocity. Although upstream reciprocity is often observed in experiments, most theories suggest that it is operative only when players form short cycles such as triangles, implying a small population size, or when it is combined with other mechanisms that promote cooperation on their own. An expectation is that real social networks, which are known to be full of triangles and other short cycles, may accommodate upstream reciprocity. In this study, I extend the upstream reciprocity game proposed for a directed cycle by Boyd and Richerson to the case of general networks. The model is not evolutionary and concerns the conditions under which the unanimity of cooperative players is a Nash equilibrium. I show that an abundance of triangles or other short cycles in a network does little to promote upstream reciprocity. Cooperation is less likely for a larger population size even if triangles are abundant in the network. In addition, in contrast to the results for evolutionary social dilemma games on networks, scale-free networks lead to less cooperation than networks with a homogeneous degree distribution.

Clustering in Large Networks Does Not Promote Upstream Reciprocity

PubMed Central

Masuda, Naoki

2011-01-01

Upstream reciprocity (also called generalized reciprocity) is a putative mechanism for cooperation in social dilemma situations with which players help others when they are helped by somebody else. It is a type of indirect reciprocity. Although upstream reciprocity is often observed in experiments, most theories suggest that it is operative only when players form short cycles such as triangles, implying a small population size, or when it is combined with other mechanisms that promote cooperation on their own. An expectation is that real social networks, which are known to be full of triangles and other short cycles, may accommodate upstream reciprocity. In this study, I extend the upstream reciprocity game proposed for a directed cycle by Boyd and Richerson to the case of general networks. The model is not evolutionary and concerns the conditions under which the unanimity of cooperative players is a Nash equilibrium. I show that an abundance of triangles or other short cycles in a network does little to promote upstream reciprocity. Cooperation is less likely for a larger population size even if triangles are abundant in the network. In addition, in contrast to the results for evolutionary social dilemma games on networks, scale-free networks lead to less cooperation than networks with a homogeneous degree distribution. PMID:21998641

The Impact of Online Social Networks on Health and Health Systems: A Scoping Review and Case Studies.

PubMed

Griffiths, Frances; Dobermann, Tim; Cave, Jonathan A K; Thorogood, Margaret; Johnson, Samantha; Salamatian, Kavé; Gomez Olive, Francis X; Goudge, Jane

2015-12-01

Interaction through online social networks potentially results in the contestation of prevailing ideas about health and health care, and to mass protest where health is put at risk or health care provision is wanting. Through a review of the academic literature and case studies of four social networking health sites (PatientsLikeMe, Mumsnet, Treatment Action Campaign, and My Pro Ana), we establish the extent to which this phenomenon is documented, seek evidence of the prevalence and character of health-related networks, and explore their structure, function, participants, and impact, seeking to understand how they came into being and how they sustain themselves. Results indicate mass protest is not arising from these established health-related networking platforms. There is evidence of changes in policy following campaigning activity prompted by experiences shared through social networking such as improved National Health Service care for miscarriage (a Mumsnet campaign). Platform owners and managers have considerable power to shape these campaigns. Social networking is also influencing health policy indirectly through increasing awareness and so demand for health care. Transient social networking about health on platforms such as Twitter were not included as case studies but may be where the most radical or destabilizing influence on health care policy might arise.

The Impact of Online Social Networks on Health and Health Systems: A Scoping Review and Case Studies

PubMed Central

Griffiths, Frances; Dobermann, Tim; Cave, Jonathan A. K.; Thorogood, Margaret; Johnson, Samantha; Salamatian, Kavé; Gomez Olive, Francis X.; Goudge, Jane

2015-01-01

Interaction through online social networks potentially results in the contestation of prevailing ideas about health and health care, and to mass protest where health is put at risk or health care provision is wanting. Through a review of the academic literature and case studies of four social networking health sites (PatientsLikeMe, Mumsnet, Treatment Action Campaign, and My Pro Ana), we establish the extent to which this phenomenon is documented, seek evidence of the prevalence and character of health‐related networks, and explore their structure, function, participants, and impact, seeking to understand how they came into being and how they sustain themselves. Results indicate mass protest is not arising from these established health‐related networking platforms. There is evidence of changes in policy following campaigning activity prompted by experiences shared through social networking such as improved National Health Service care for miscarriage (a Mumsnet campaign). Platform owners and managers have considerable power to shape these campaigns. Social networking is also influencing health policy indirectly through increasing awareness and so demand for health care. Transient social networking about health on platforms such as Twitter were not included as case studies but may be where the most radical or destabilizing influence on health care policy might arise. PMID:27134699

Gene function prediction with gene interaction networks: a context graph kernel approach.

PubMed

Li, Xin; Chen, Hsinchun; Li, Jiexun; Zhang, Zhu

2010-01-01

Predicting gene functions is a challenge for biologists in the postgenomic era. Interactions among genes and their products compose networks that can be used to infer gene functions. Most previous studies adopt a linkage assumption, i.e., they assume that gene interactions indicate functional similarities between connected genes. In this study, we propose to use a gene's context graph, i.e., the gene interaction network associated with the focal gene, to infer its functions. In a kernel-based machine-learning framework, we design a context graph kernel to capture the information in context graphs. Our experimental study on a testbed of p53-related genes demonstrates the advantage of using indirect gene interactions and shows the empirical superiority of the proposed approach over linkage-assumption-based methods, such as the algorithm to minimize inconsistent connected genes and diffusion kernels.

Hybrid Adaptive Flight Control with Model Inversion Adaptation

NASA Technical Reports Server (NTRS)

Nguyen, Nhan

2011-01-01

This study investigates a hybrid adaptive flight control method as a design possibility for a flight control system that can enable an effective adaptation strategy to deal with off-nominal flight conditions. The hybrid adaptive control blends both direct and indirect adaptive control in a model inversion flight control architecture. The blending of both direct and indirect adaptive control provides a much more flexible and effective adaptive flight control architecture than that with either direct or indirect adaptive control alone. The indirect adaptive control is used to update the model inversion controller by an on-line parameter estimation of uncertain plant dynamics based on two methods. The first parameter estimation method is an indirect adaptive law based on the Lyapunov theory, and the second method is a recursive least-squares indirect adaptive law. The model inversion controller is therefore made to adapt to changes in the plant dynamics due to uncertainty. As a result, the modeling error is reduced that directly leads to a decrease in the tracking error. In conjunction with the indirect adaptive control that updates the model inversion controller, a direct adaptive control is implemented as an augmented command to further reduce any residual tracking error that is not entirely eliminated by the indirect adaptive control.

Indirect Comparisons: A Review of Reporting and Methodological Quality

PubMed Central

Donegan, Sarah; Williamson, Paula; Gamble, Carrol; Tudur-Smith, Catrin

2010-01-01

Background The indirect comparison of two interventions can be valuable in many situations. However, the quality of an indirect comparison will depend on several factors including the chosen methodology and validity of underlying assumptions. Published indirect comparisons are increasingly more common in the medical literature, but as yet, there are no published recommendations of how they should be reported. Our aim is to systematically review the quality of published indirect comparisons to add to existing empirical data suggesting that improvements can be made when reporting and applying indirect comparisons. Methodology/Findings Reviews applying statistical methods to indirectly compare the clinical effectiveness of two interventions using randomised controlled trials were eligible. We searched (1966–2008) Database of Abstracts and Reviews of Effects, The Cochrane library, and Medline. Full review publications were assessed for eligibility. Specific criteria to assess quality were developed and applied. Forty-three reviews were included. Adequate methodology was used to calculate the indirect comparison in 41 reviews. Nineteen reviews assessed the similarity assumption using sensitivity analysis, subgroup analysis, or meta-regression. Eleven reviews compared trial-level characteristics. Twenty-four reviews assessed statistical homogeneity. Twelve reviews investigated causes of heterogeneity. Seventeen reviews included direct and indirect evidence for the same comparison; six reviews assessed consistency. One review combined both evidence types. Twenty-five reviews urged caution in interpretation of results, and 24 reviews indicated when results were from indirect evidence by stating this term with the result. Conclusions This review shows that the underlying assumptions are not routinely explored or reported when undertaking indirect comparisons. We recommend, therefore, that the quality of indirect comparisons should be improved, in particular, by assessing assumptions and reporting the assessment methods applied. We propose that the quality criteria applied in this article may provide a basis to help review authors carry out indirect comparisons and to aid appropriate interpretation. PMID:21085712

Powering up with indirect reciprocity in a large-scale field experiment

PubMed Central

Yoeli, Erez; Hoffman, Moshe; Rand, David G.; Nowak, Martin A.

2013-01-01

A defining aspect of human cooperation is the use of sophisticated indirect reciprocity. We observe others, talk about others, and act accordingly. We help those who help others, and we cooperate expecting that others will cooperate in return. Indirect reciprocity is based on reputation, which spreads by communication. A crucial aspect of indirect reciprocity is observability: reputation effects can support cooperation as long as peoples’ actions can be observed by others. In evolutionary models of indirect reciprocity, natural selection favors cooperation when observability is sufficiently high. Complimenting this theoretical work are experiments where observability promotes cooperation among small groups playing games in the laboratory. Until now, however, there has been little evidence of observability’s power to promote large-scale cooperation in real world settings. Here we provide such evidence using a field study involving 2413 subjects. We collaborated with a utility company to study participation in a program designed to prevent blackouts. We show that observability triples participation in this public goods game. The effect is over four times larger than offering a $25 monetary incentive, the company’s previous policy. Furthermore, as predicted by indirect reciprocity, we provide evidence that reputational concerns are driving our observability effect. In sum, we show how indirect reciprocity can be harnessed to increase cooperation in a relevant, real-world public goods game. PMID:23754399

Spatially complex land change: The Indirect effect of Brazil's agricultural sector on land use in Amazonia

PubMed Central

Richards, Peter D.; Walker, Robert T.; Arima, Eugenio Y.

2014-01-01

Soybean farming has brought economic development to parts of South America, as well as environmental hopes and concerns. A substantial hope resides in the decoupling of Brazil's agricultural sector from deforestation in the Amazon region, in which case expansive agriculture need not imply forest degradation. However, concerns have also been voiced about the potential indirect effects of agriculture. This article addresses these indirect effects forthe case of the Brazilian Amazon since 2002. Our work finds that as much as thirty-two percent of deforestation, or the loss of more than 30,000 km2 of Amazon forest, is attributable, indirectly, to Brazil's soybean sector. However, we also observe that the magnitude of the indirect impact of the agriculture sector on forest loss in the Amazon has declined markedly since 2006. We also find a shift in the underlying causes of indirect land use change in the Amazon, and suggest that land appreciation in agricultural regions has supplanted farm expansions as a source of indirect land use change. Our results are broadly congruent with recent work recognizing the success of policy changes in mitigating the impact of soybean expansion on forest loss in the Amazon. However, they also caution that the soybean sector may continue to incentivize land clearings through its impact on regional land markets. PMID:25492993

Development and Evaluation of a UAV-Photogrammetry System for Precise 3D Environmental Modeling.

PubMed

Shahbazi, Mozhdeh; Sohn, Gunho; Théau, Jérôme; Menard, Patrick

2015-10-30

The specific requirements of UAV-photogrammetry necessitate particular solutions for system development, which have mostly been ignored or not assessed adequately in recent studies. Accordingly, this paper presents the methodological and experimental aspects of correctly implementing a UAV-photogrammetry system. The hardware of the system consists of an electric-powered helicopter, a high-resolution digital camera and an inertial navigation system. The software of the system includes the in-house programs specifically designed for camera calibration, platform calibration, system integration, on-board data acquisition, flight planning and on-the-job self-calibration. The detailed features of the system are discussed, and solutions are proposed in order to enhance the system and its photogrammetric outputs. The developed system is extensively tested for precise modeling of the challenging environment of an open-pit gravel mine. The accuracy of the results is evaluated under various mapping conditions, including direct georeferencing and indirect georeferencing with different numbers, distributions and types of ground control points. Additionally, the effects of imaging configuration and network stability on modeling accuracy are assessed. The experiments demonstrated that 1.55 m horizontal and 3.16 m vertical absolute modeling accuracy could be achieved via direct geo-referencing, which was improved to 0.4 cm and 1.7 cm after indirect geo-referencing.

Development and Evaluation of a UAV-Photogrammetry System for Precise 3D Environmental Modeling

PubMed Central

Shahbazi, Mozhdeh; Sohn, Gunho; Théau, Jérôme; Menard, Patrick

2015-01-01

The specific requirements of UAV-photogrammetry necessitate particular solutions for system development, which have mostly been ignored or not assessed adequately in recent studies. Accordingly, this paper presents the methodological and experimental aspects of correctly implementing a UAV-photogrammetry system. The hardware of the system consists of an electric-powered helicopter, a high-resolution digital camera and an inertial navigation system. The software of the system includes the in-house programs specifically designed for camera calibration, platform calibration, system integration, on-board data acquisition, flight planning and on-the-job self-calibration. The detailed features of the system are discussed, and solutions are proposed in order to enhance the system and its photogrammetric outputs. The developed system is extensively tested for precise modeling of the challenging environment of an open-pit gravel mine. The accuracy of the results is evaluated under various mapping conditions, including direct georeferencing and indirect georeferencing with different numbers, distributions and types of ground control points. Additionally, the effects of imaging configuration and network stability on modeling accuracy are assessed. The experiments demonstrated that 1.55 m horizontal and 3.16 m vertical absolute modeling accuracy could be achieved via direct geo-referencing, which was improved to 0.4 cm and 1.7 cm after indirect geo-referencing. PMID:26528976

Alexithymia, Assertiveness and Psychosocial Functioning in HIV: Implications for Medication Adherence and Disease Severity.

PubMed

McIntosh, Roger C; Ironson, Gail; Antoni, Michael; Fletcher, Mary Ann; Schneiderman, Neil

2016-02-01

Psychosocial function and adherence to antiretroviral regimen are key factors in human immunodeficiency virus (HIV) disease management. Alexithymia (AL) is a trait deficit in the ability to identify and describe feelings, emotions and bodily sensations. A structural equation model was used to test whether high levels of AL indirectly relate to greater non-adherent behavior and HIV disease severity via psychosocial dysfunction. Blood draws for HIV-1 viral load and CD4 T-lymphocyte, along with psychosocial surveys were collected from 439 HIV positive adults aged 18-73 years. The structural model supports significant paths from: (1) AL to non-active patient involvement, psychological distress, and lower social support, (2) psychological distress and non-active involvement to non-adherent behavior, and (3) non-adherence to greater HIV disease severity (CFI = .97, RMSEA = .04, SRMR = .05). A second model confirmed the intermediary effect of greater patient assertiveness on the path from AL to social support and non-active patient involvement (CFI = .94, RMSEA = .04, SRMR = .05). Altogether, AL is indirectly linked with HIV disease management through it's association with poor psychosocial function, however greater patient assertiveness buffers the negative impact of AL on relationship quality with healthcare providers and members of one's social support network.

Optical band gap and spectroscopic study of lithium alumino silicate glass containing Y 3+ ions

NASA Astrophysics Data System (ADS)

Shakeri, M. S.; Rezvani, M.

2011-09-01

The effect of different amounts of Y 2O 3 dopant on lithium alumino silicate (LAS) glass has been studied in this work. Glasses having 14.8Li 2O-20Al 2O 3-65.2SiO 2 (wt%) composition accompanied with Y 2O 3 dopant were prepared by normal melting process. In order to calculate the absorption coefficient of samples, transmittance and reflectance spectra of polished samples were measured in the room temperature. Optical properties i.e. Fermi energy level, direct and indirect optical band gaps and Urbach energy were calculated using functionality of extinction coefficient from Fermi-Dirac distribution function, Tauc's plot and the exponential part of absorption coefficient diagram, respectively. It has been clarified that variation in mentioned optical parameters is associated with the changes in physical properties of samples i.e. density or molar mass. On the other hand, increasing of Y 3+ ions in the glassy microstructure of samples provides a semiconducting character to LAS glass by reducing the direct and indirect optical band gaps of glass samples from 1.97 to 1.67 and 3.46 to 2.1 (eV), respectively. These changes could be attributed to the role of Y 3+ ions as the network former in the track of SiO 4 tetrahedrals.

Antithrombotic therapy in patients receiving saphenous vein coronary artery bypass grafts: a protocol for a systematic review and network meta-analysis.

PubMed

Solo, Karla; Martin, Janet; Lavi, Shahar; Kabali, Conrad; John-Baptiste, Ava; Nevis, Immaculate F; Choudhury, Tawfiq; Mamas, Mamas A; Bagur, Rodrigo

2018-04-07

The current evidence for the prevention of saphenous vein graft failure (SVGF) after coronary artery bypass graft (CABG) surgery consists of direct head-to-head comparison of treatments (including placebo) in randomised-controlled trials (RCTs) and observational studies. However, summarising the evidence using traditional pairwise meta-analyses does not allow the inclusion of data from treatments that have not been compared head to head. Exclusion of such comparisons could impact the precision of pooled estimates in a meta-analysis. Hence, to address the challenge of whether aspirin alone or in addition to another antithrombotic agent is a more effective regimen to improve SVG patency, a network meta-analysis (NMA) is necessary. The objectives of this study are to synthesise the available evidence on antithrombotic agents (or their combination) and estimate the treatment effects among direct and indirect treatment comparisons on SVGF and major adverse cardiovascular events, and to generate a treatment ranking according to their efficacy and safety outcomes. We will perform a systematic review of RCTs evaluating antithrombotic agents in patients undergoing CABG. A comprehensive English literature search will be conducted using electronic databases and grey literature resources to identify published and unpublished articles. Two individuals will independently and in duplicate screen potential studies, assess the eligibility of potential studies and extract data. Risk of bias and quality of evidence will also be evaluated independently and in duplicate. We will investigate the data to ensure its suitability for NMA, including adequacy of the outcome data and transitivity of treatment effects. We plan to estimate the pooled direct, indirect and the mixed effects for all antithrombotic agents using a NMA. Due to the nature of the study, there are no ethical concerns nor informed consent required. We anticipate that this NMA will be the first to simultaneously assess the relative effects of multiple antithrombotic agents in patients undergoing CABG. The results of this NMA will inform clinicians, patients and guideline developers the best available evidence on comparative effects benefits of antithrombotic agents after CABG while considering the side effect profile to support future clinical decision-making. We will disseminate the results of our systematic review and NMA through a peer-reviewed journal. CRD42017065678. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Pre-Hurricane Perceived Social Support Protects Against Psychological Distress: A Longitudinal Analysis of Low-Income Mothers

PubMed Central

Lowe, Sarah R.; Chan, Christian S.; Rhodes, Jean E.

2013-01-01

Objective In this study, we examined the influence of pre-disaster perceived social support on post-disaster psychological distress among survivors of Hurricane Katrina. Method Participants (N = 386) were low-income mothers between 18 and 34 years of age at baseline (M = 26.4, SD = 4.43). The majority (84.8%) was African American; 10.4% identified as Caucasian, 3.2% identified as Hispanic, and 1.8% identified as other. Participants were enrolled in an educational intervention study in 2004 and 2005. Those who had completed a 1-year follow-up assessment prior to Hurricane Katrina were reassessed approximately 1 year after the hurricane. Measures of perceived social support and psychological distress were included in pre-and post-disaster assessments. Using structural equation modeling and multiple mediator analysis, we tested a model wherein pre-disaster perceived social support predicted post-disaster psychological distress both directly and indirectly through its effects on pre-disaster psychological distress, exposure to hurricane-related stressors, and post-disaster perceived social support. We predicted that higher pre-disaster perceived social support would be predictive of lower pre-disaster psychological distress, lower hurricane-related stressors, and higher post-disaster perceived social support, and that these variables would, in turn, predict lower post-disaster psychologically distress. Results Our analyses provide partial support for the hypothesized model. Although pre-disaster perceived social support did not exert a direct effect on post-disaster psychological distress, the indirect effects of all 3 proposed mediators were significant. Conclusions Pre-disaster social support can decrease both exposure to natural disasters and the negative psychological effects of natural disaster exposure. These findings underscore the importance of bolstering the post-disaster social support networks of low-income mothers. PMID:20658811

The fate of threatened coastal dune habitats in Italy under climate change scenarios.

PubMed

Prisco, Irene; Carboni, Marta; Acosta, Alicia T R

2013-01-01

Coastal dunes worldwide harbor threatened habitats characterized by high diversity in terms of plant communities. In Italy, recent assessments have highlighted the insufficient state of conservation of these habitats as defined by the EU Habitats Directive. The effects of predicted climate change could have dramatic consequences for coastal environments in the near future. An assessment of the efficacy of protection measures under climate change is thus a priority. Here, we have developed environmental envelope models for the most widespread dune habitats in Italy, following two complementary approaches: an "indirect" plant-species-based one and a simple "direct" one. We analyzed how habitats distribution will be altered under the effects of two climate change scenarios and evaluated if the current Italian network of protected areas will be effective in the future after distribution shifts. While modeling dune habitats with the "direct" approach was unsatisfactory, "indirect" models had a good predictive performance, highlighting the importance of using species' responses to climate change for modeling these habitats. The results showed that habitats closer to the sea may even increase their geographical distribution in the near future. The transition dune habitat is projected to remain stable, although mobile and fixed dune habitats are projected to lose most of their actual geographical distribution, the latter being more sensitive to climate change effects. Gap analysis highlighted that the habitats' distribution is currently adequately covered by protected areas, achieving the conservation target. However, according to predictions, protection level for mobile and fixed dune habitats is predicted to drop drastically under the climate change scenarios which we examined. Our results provide useful insights for setting management priorities and better addressing conservation efforts to preserve these threatened habitats in future.

Human impacts to mountain streams

NASA Astrophysics Data System (ADS)

Wohl, Ellen

2006-09-01

Mountain streams are here defined as channel networks within mountainous regions of the world. This definition encompasses tremendous diversity of physical and biological conditions, as well as history of land use. Human effects on mountain streams may result from activities undertaken within the stream channel that directly alter channel geometry, the dynamics of water and sediment movement, contaminants in the stream, or aquatic and riparian communities. Examples include channelization, construction of grade-control structures or check dams, removal of beavers, and placer mining. Human effects can also result from activities within the watershed that indirectly affect streams by altering the movement of water, sediment, and contaminants into the channel. Deforestation, cropping, grazing, land drainage, and urbanization are among the land uses that indirectly alter stream processes. An overview of the relative intensity of human impacts to mountain streams is provided by a table summarizing human effects on each of the major mountainous regions with respect to five categories: flow regulation, biotic integrity, water pollution, channel alteration, and land use. This table indicates that very few mountains have streams not at least moderately affected by land use. The least affected mountainous regions are those at very high or very low latitudes, although our scientific ignorance of conditions in low-latitude mountains in particular means that streams in these mountains might be more altered than is widely recognized. Four case studies from northern Sweden (arctic region), Colorado Front Range (semiarid temperate region), Swiss Alps (humid temperate region), and Papua New Guinea (humid tropics) are also used to explore in detail the history and effects on rivers of human activities in mountainous regions. The overview and case studies indicate that mountain streams must be managed with particular attention to upstream/downstream connections, hillslope/channel connections, process domains, physical and ecological roles of disturbance, and stream resilience.

Risks, Risk Factors, and Outcomes Associated with Phone and Internet Sexting Among University Students in the United States.

PubMed

Dir, Allyson L; Cyders, Melissa A

2015-08-01

Sexting, defined as the exchange of sexually suggestive pictures or messages via mobile phone or social networking sites (SNS), has received media attention for its prevalence and associated negative outcomes; however, research has not yet fully established risk factors for and resulting outcomes from sexting behaviors. The current study was the first empirical test of a causal path model in males and females, in which impulsivity-related traits and expectancies influence sexual behaviors through phone and SNS sexting. We also examined prevalence and perceived likelihood of common negative outcomes associated with sexting. Multiple regression and structural equation modeling (SEM) statistics were conducted on two independent undergraduate samples (n = 611 and 255). The best fitting SEM model (RMSEA = 0.04, CFI = 0.96, TLI = 0.94, and χ(2) = 176.06, df = 75, p < .001) demonstrated a significant indirect effect of sensation seeking on phone sexting behaviors through sex-related sexting expectancies and a significant indirect effect of sensation seeking on sexual hookup behaviors through phone sexting behaviors (b = 0.06, p = .03), but only for females. Reverse mediations and mediation with SNS were not significant. Negative outcomes were rare: sexts being spread to others was the most common negative sexting experience (n = 21, 12 %). This study suggests the viability of personality and expectancies affecting sexual hookup behaviors through engagement in sexting behaviors. It also suggests that although direct negative outcomes associated with sexting are thought to be common, they were rare in the current sample.

OH radicals from the indirect actions of X-rays induce cell lethality and mediate the majority of the oxygen enhancement effect.

PubMed

Hirayama, Ryoichi; Ito, Atsushi; Noguchi, Miho; Matsumoto, Yoshitaka; Uzawa, Akiko; Kobashi, Gen; Okayasu, Ryuichi; Furusawa, Yoshiya

2013-11-01

We examined OH radical-mediated indirect actions from X irradiation on cell killing in wild-type Chinese hamster ovary cell lines (CHO and AA8) under oxic and hypoxic conditions, and compared the contribution of direct and indirect actions under both conditions. The contribution of indirect action on cell killing can be estimated from the maximum degree of protection by dimethylsulfoxide, which suppresses indirect action by quenching OH radicals without affecting the direct action of X rays on cell killing. The contributions of indirect action on cell killing of CHO cells were 76% and 50% under oxic and hypoxic conditions, respectively, and those for AA8 cells were 85% and 47%, respectively. Therefore, the indirect action on cell killing was enhanced by oxygen during X irradiation in both cell lines tested. Oxygen enhancement ratios (OERs) at the 10% survival level (D10 or LD90) for CHO and AA8 cells were 2.68 ± 0.15 and 2.76 ± 0.08, respectively. OERs were evaluated separately for indirect and direct actions, which gave the values of 3.75 and 2.01 for CHO, and 4.11 and 1.32 for AA8 cells, respectively. Thus the generally accepted OER value of ∼3 is best understood as the average of the OER values for both indirect and direct actions. These results imply that both indirect and direct actions on cell killing require oxygen for the majority of lethal DNA damage, however, oxygen plays a larger role in indirect than for direct effects. Conversely, the lethal damage induced by the direct action of X rays are less affected by oxygen concentration.