CNNcon: improved protein contact maps prediction using cascaded neural networks.

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Wang Ding

Full Text Available BACKGROUNDS: Despite continuing progress in X-ray crystallography and high-field NMR spectroscopy for determination of three-dimensional protein structures, the number of unsolved and newly discovered sequences grows much faster than that of determined structures. Protein modeling methods can possibly bridge this huge sequence-structure gap with the development of computational science. A grand challenging problem is to predict three-dimensional protein structure from its primary structure (residues sequence alone. However, predicting residue contact maps is a crucial and promising intermediate step towards final three-dimensional structure prediction. Better predictions of local and non-local contacts between residues can transform protein sequence alignment to structure alignment, which can finally improve template based three-dimensional protein structure predictors greatly. METHODS: CNNcon, an improved multiple neural networks based contact map predictor using six sub-networks and one final cascade-network, was developed in this paper. Both the sub-networks and the final cascade-network were trained and tested with their corresponding data sets. While for testing, the target protein was first coded and then input to its corresponding sub-networks for prediction. After that, the intermediate results were input to the cascade-network to finish the final prediction. RESULTS: The CNNcon can accurately predict 58.86% in average of contacts at a distance cutoff of 8 Å for proteins with lengths ranging from 51 to 450. The comparison results show that the present method performs better than the compared state-of-the-art predictors. Particularly, the prediction accuracy keeps steady with the increase of protein sequence length. It indicates that the CNNcon overcomes the thin density problem, with which other current predictors have trouble. This advantage makes the method valuable to the prediction of long length proteins. As a result, the effective

Diagnosis of Constant Faults in Read-Once Contact Networks over Finite Bases using Decision Trees

KAUST Repository

Busbait, Monther I.

2014-05-01

We study the depth of decision trees for diagnosis of constant faults in read-once contact networks over finite bases. This includes diagnosis of 0-1 faults, 0 faults and 1 faults. For any finite basis, we prove a linear upper bound on the minimum depth of decision tree for diagnosis of constant faults depending on the number of edges in a contact network over that basis. Also, we obtain asymptotic bounds on the depth of decision trees for diagnosis of each type of constant faults depending on the number of edges in contact networks in the worst case per basis. We study the set of indecomposable contact networks with up to 10 edges and obtain sharp coefficients for the linear upper bound for diagnosis of constant faults in contact networks over bases of these indecomposable contact networks. We use a set of algorithms, including one that we create, to obtain the sharp coefficients.

Diagnostic reasoning and underlying knowledge of students with preclinical patient contacts in PBL.

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Diemers, Agnes D; van de Wiel, Margje W J; Scherpbier, Albert J J A; Baarveld, Frank; Dolmans, Diana H J M

2015-12-01

Medical experts have access to elaborate and integrated knowledge networks consisting of biomedical and clinical knowledge. These coherent knowledge networks enable them to generate more accurate diagnoses in a shorter time. However, students' knowledge networks are less organised and students have difficulties linking theory and practice and transferring acquired knowledge. Therefore we wanted to explore the development and transfer of knowledge of third-year preclinical students on a problem-based learning (PBL) course with real patient contacts. Before and after a 10-week PBL course with real patients, third-year medical students were asked to think out loud while diagnosing four types of paper patient problems (two course cases and two transfer cases), and explain the underlying pathophysiological mechanisms of the patient features. Diagnostic accuracy and time needed to think through the cases were measured. The think-aloud protocols were transcribed verbatim and different types of knowledge were coded and quantitatively analysed. The written pathophysiological explanations were translated into networks of concepts. Both the concepts and the links between concepts in students' networks were compared to model networks. Over the course diagnostic accuracy increased, case-processing time decreased, and students used less biomedical and clinical knowledge during diagnostic reasoning. The quality of the pathophysiological explanations increased: the students used more concepts, especially more model concepts, and they used fewer wrong concepts and links. The findings differed across course and transfer cases. The effects were generally less strong for transfer cases. Students' improved diagnostic accuracy and the improved quality of their knowledge networks suggest that integration of biomedical and clinical knowledge took place during a 10-week course. The differences between course and transfer cases demonstrate that transfer is complex and time-consuming. We

Effects of contact network structure on epidemic transmission trees: implications for data required to estimate network structure.

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Carnegie, Nicole Bohme

2018-01-30

Understanding the dynamics of disease spread is key to developing effective interventions to control or prevent an epidemic. The structure of the network of contacts over which the disease spreads has been shown to have a strong influence on the outcome of the epidemic, but an open question remains as to whether it is possible to estimate contact network features from data collected in an epidemic. The approach taken in this paper is to examine the distributions of epidemic outcomes arising from epidemics on networks with particular structural features to assess whether that structure could be measured from epidemic data and what other constraints might be needed to make the problem identifiable. To this end, we vary the network size, mean degree, and transmissibility of the pathogen, as well as the network feature of interest: clustering, degree assortativity, or attribute-based preferential mixing. We record several standard measures of the size and spread of the epidemic, as well as measures that describe the shape of the transmission tree in order to ascertain whether there are detectable signals in the final data from the outbreak. The results suggest that there is potential to estimate contact network features from transmission trees or pure epidemic data, particularly for diseases with high transmissibility or for which the relevant contact network is of low mean degree. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

The Potential Role of Direct and Indirect Contacts on Infection Spread in Dairy Farm Networks.

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Gianluigi Rossi

2017-01-01

Full Text Available Animals' exchanges are considered the most effective route of between-farm infectious disease transmission. However, despite being often overlooked, the infection spread due to contaminated equipment, vehicles, or personnel proved to be important for several livestock epidemics. This study investigated the role of indirect contacts in a potential infection spread in the dairy farm network of the Province of Parma (Northern Italy. We built between-farm contact networks using data on cattle exchange (direct contacts, and on-farm visits by veterinarians (indirect contacts. We compared the features of the contact structures by using measures on static and temporal networks. We assessed the disease spreading potential of the direct and indirect network structures in the farm system by using data on the infection state of farms by paratuberculosis. Direct and indirect networks showed non-trivial differences with respect to connectivity, contact distribution, and super-spreaders identification. Furthermore, our analyses on paratuberculosis data suggested that the contributions of direct and indirect contacts on diseases spread are apparent at different spatial scales. Our results highlighted the potential role of indirect contacts in between-farm disease spread and underlined the need for a deeper understanding of these contacts to develop better strategies for prevention of livestock epidemics.

Controlling infectious disease through the targeted manipulation of contact network structure

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M. Carolyn Gates

2015-09-01

Full Text Available Individuals in human and animal populations are linked through dynamic contact networks with characteristic structural features that drive the epidemiology of directly transmissible infectious diseases. Using animal movement data from the British cattle industry as an example, this analysis explores whether disease dynamics can be altered by placing targeted restrictions on contact formation to reconfigure network topology. This was accomplished using a simple network generation algorithm that combined configuration wiring with stochastic block modelling techniques to preserve the weighted in- and out-degree of individual nodes (farms as well as key demographic characteristics of the individual network connections (movement date, livestock market, and animal production type. We then tested a control strategy based on introducing additional constraints into the network generation algorithm to prevent farms with a high in-degree from selling cattle to farms with a high out-degree as these particular network connections are predicted to have a disproportionately strong role in spreading disease. Results from simple dynamic disease simulation models predicted significantly lower endemic disease prevalences on the trade restricted networks compared to the baseline generated networks. As expected, the relative magnitude of the predicted changes in endemic prevalence was greater for diseases with short infectious periods and low transmission probabilities. Overall, our study findings demonstrate that there is significant potential for controlling multiple infectious diseases simultaneously by manipulating networks to have more epidemiologically favourable topological configurations. Further research is needed to determine whether the economic and social benefits of controlling disease can justify the costs of restricting contact formation.

Controlling infectious disease through the targeted manipulation of contact network structure

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Gates, M. Carolyn; Woolhouse, Mark E.J.

2015-01-01

Individuals in human and animal populations are linked through dynamic contact networks with characteristic structural features that drive the epidemiology of directly transmissible infectious diseases. Using animal movement data from the British cattle industry as an example, this analysis explores whether disease dynamics can be altered by placing targeted restrictions on contact formation to reconfigure network topology. This was accomplished using a simple network generation algorithm that combined configuration wiring with stochastic block modelling techniques to preserve the weighted in- and out-degree of individual nodes (farms) as well as key demographic characteristics of the individual network connections (movement date, livestock market, and animal production type). We then tested a control strategy based on introducing additional constraints into the network generation algorithm to prevent farms with a high in-degree from selling cattle to farms with a high out-degree as these particular network connections are predicted to have a disproportionately strong role in spreading disease. Results from simple dynamic disease simulation models predicted significantly lower endemic disease prevalences on the trade restricted networks compared to the baseline generated networks. As expected, the relative magnitude of the predicted changes in endemic prevalence was greater for diseases with short infectious periods and low transmission probabilities. Overall, our study findings demonstrate that there is significant potential for controlling multiple infectious diseases simultaneously by manipulating networks to have more epidemiologically favourable topological configurations. Further research is needed to determine whether the economic and social benefits of controlling disease can justify the costs of restricting contact formation. PMID:26342238

Controlling infectious disease through the targeted manipulation of contact network structure.

Science.gov (United States)

Gates, M Carolyn; Woolhouse, Mark E J

2015-09-01

Individuals in human and animal populations are linked through dynamic contact networks with characteristic structural features that drive the epidemiology of directly transmissible infectious diseases. Using animal movement data from the British cattle industry as an example, this analysis explores whether disease dynamics can be altered by placing targeted restrictions on contact formation to reconfigure network topology. This was accomplished using a simple network generation algorithm that combined configuration wiring with stochastic block modelling techniques to preserve the weighted in- and out-degree of individual nodes (farms) as well as key demographic characteristics of the individual network connections (movement date, livestock market, and animal production type). We then tested a control strategy based on introducing additional constraints into the network generation algorithm to prevent farms with a high in-degree from selling cattle to farms with a high out-degree as these particular network connections are predicted to have a disproportionately strong role in spreading disease. Results from simple dynamic disease simulation models predicted significantly lower endemic disease prevalences on the trade restricted networks compared to the baseline generated networks. As expected, the relative magnitude of the predicted changes in endemic prevalence was greater for diseases with short infectious periods and low transmission probabilities. Overall, our study findings demonstrate that there is significant potential for controlling multiple infectious diseases simultaneously by manipulating networks to have more epidemiologically favourable topological configurations. Further research is needed to determine whether the economic and social benefits of controlling disease can justify the costs of restricting contact formation. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Sheet resistance under Ohmic contacts to AlGaN/GaN heterostructures

NARCIS (Netherlands)

Hajlasz, M.; Donkers, J.J.T.M.; Sque, S.J.; Heil, S.B.S.; Gravesteijn, Dirk J; Rietveld, F.J.R.; Schmitz, Jurriaan

2014-01-01

For the determination of specific contact resistance in semiconductor devices, it is usually assumed that the sheet resistance under the contact is identical to that between the contacts. This generally does not hold for contacts to AlGaN/GaN structures, where an effective doping under the contact

Network analysis of pig movements: Loyalty patterns and contact chains of different holding types in Denmark.

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Schulz, Jana; Boklund, Anette; Halasa, Tariq H B; Toft, Nils; Lentz, Hartmut H K

2017-01-01

Understanding animal movements is an important factor for the development of meaningful surveillance and control programs, but also for the development of disease spread models. We analysed the Danish pig movement network using static and temporal network analysis tools to provide deeper insight in the connection between holdings dealing with pigs, such as breeding and multiplier herds, production herds, slaughterhouses or traders. Pig movements, which occurred between 1st January 2006 and 31st December 2015 in Denmark, were summarized to investigate temporal trends such as the number of active holdings, the number of registered movements and the number of pigs moved. To identify holdings and holding types with potentially higher risk for introduction or spread of diseases via pig movements, we determined loyalty patterns, annual network components and contact chains for the 24 registered holding types. The total number of active holdings as well as the number of pig movements decreased during the study period while the holding sizes increased. Around 60-90% of connections between two pig holdings were present in two consecutive years and around one third of the connections persisted within the considered time period. Weaner herds showed the highest level of in-loyalty, whereas we observed an intermediate level of in-loyalty for all breeding sites and for production herds. Boar stations, production herds and trade herds showed a high level of out-loyalty. Production herds constituted the highest proportion of holdings in the largest strongly connected component. All production sites showed low levels of in-going contact chains and we observed a high level of out-going contact chain for breeding and multiplier herds. Except for livestock auctions, all transit sites also showed low levels of out-going contact chains. Our results reflect the pyramidal structure of the underlying network. Based on the considered disease, the time frame for the calculation of network

Network analysis of pig movements: Loyalty patterns and contact chains of different holding types in Denmark.

Directory of Open Access Journals (Sweden)

Jana Schulz

Full Text Available Understanding animal movements is an important factor for the development of meaningful surveillance and control programs, but also for the development of disease spread models. We analysed the Danish pig movement network using static and temporal network analysis tools to provide deeper insight in the connection between holdings dealing with pigs, such as breeding and multiplier herds, production herds, slaughterhouses or traders. Pig movements, which occurred between 1st January 2006 and 31st December 2015 in Denmark, were summarized to investigate temporal trends such as the number of active holdings, the number of registered movements and the number of pigs moved. To identify holdings and holding types with potentially higher risk for introduction or spread of diseases via pig movements, we determined loyalty patterns, annual network components and contact chains for the 24 registered holding types. The total number of active holdings as well as the number of pig movements decreased during the study period while the holding sizes increased. Around 60-90% of connections between two pig holdings were present in two consecutive years and around one third of the connections persisted within the considered time period. Weaner herds showed the highest level of in-loyalty, whereas we observed an intermediate level of in-loyalty for all breeding sites and for production herds. Boar stations, production herds and trade herds showed a high level of out-loyalty. Production herds constituted the highest proportion of holdings in the largest strongly connected component. All production sites showed low levels of in-going contact chains and we observed a high level of out-going contact chain for breeding and multiplier herds. Except for livestock auctions, all transit sites also showed low levels of out-going contact chains. Our results reflect the pyramidal structure of the underlying network. Based on the considered disease, the time frame for the

Modelling temporal networks of human face-to-face contacts with public activity and individual reachability

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Zhang, Yi-Qing; Cui, Jing; Zhang, Shu-Min; Zhang, Qi; Li, Xiang

2016-02-01

Modelling temporal networks of human face-to-face contacts is vital both for understanding the spread of airborne pathogens and word-of-mouth spreading of information. Although many efforts have been devoted to model these temporal networks, there are still two important social features, public activity and individual reachability, have been ignored in these models. Here we present a simple model that captures these two features and other typical properties of empirical face-to-face contact networks. The model describes agents which are characterized by an attractiveness to slow down the motion of nearby people, have event-triggered active probability and perform an activity-dependent biased random walk in a square box with periodic boundary. The model quantitatively reproduces two empirical temporal networks of human face-to-face contacts which are testified by their network properties and the epidemic spread dynamics on them.

We'll meet again: revealing distributional and temporal patterns of social contact.

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Thorsten Pachur

Full Text Available What are the dynamics and regularities underlying social contact, and how can contact with the people in one's social network be predicted? In order to characterize distributional and temporal patterns underlying contact probability, we asked 40 participants to keep a diary of their social contacts for 100 consecutive days. Using a memory framework previously used to study environmental regularities, we predicted that the probability of future contact would follow in systematic ways from the frequency, recency, and spacing of previous contact. The distribution of contact probability across the members of a person's social network was highly skewed, following an exponential function. As predicted, it emerged that future contact scaled linearly with frequency of past contact, proportionally to a power function with recency of past contact, and differentially according to the spacing of past contact. These relations emerged across different contact media and irrespective of whether the participant initiated or received contact. We discuss how the identification of these regularities might inspire more realistic analyses of behavior in social networks (e.g., attitude formation, cooperation.

Impacts of subsidy policies on vaccination decisions in contact networks

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Zhang, Hai-Feng; Wu, Zhi-Xi; Xu, Xiao-Ke; Small, Michael; Wang, Lin; Wang, Bing-Hong

2013-07-01

To motivate more people to participate in vaccination campaigns, various subsidy policies are often supplied by government and the health sectors. However, these external incentives may also alter the vaccination decisions of the broader public, and hence the choice of incentive needs to be carefully considered. Since human behavior and the networking-constrained interactions among individuals significantly impact the evolution of an epidemic, here we consider the voluntary vaccination on human contact networks. To this end, two categories of typical subsidy policies are considered: (1) under the free subsidy policy, the total amount of subsidy is distributed to a certain fraction of individual and who are vaccinated without personal cost, and (2) under the partial-offset subsidy policy, each vaccinated person is offset by a certain amount of subsidy. A vaccination decision model based on evolutionary game theory is established to study the effects of these different subsidy policies on disease control. Simulations suggest that, because the partial-offset subsidy policy encourages more people to take vaccination, its performance is significantly better than that of the free subsidy policy. However, an interesting phenomenon emerges in the partial-offset scenario: with limited amount of total subsidy, a moderate subsidy rate for each vaccinated individual can guarantee the group-optimal vaccination, leading to the maximal social benefits, while such an optimal phenomenon is not evident for the free subsidy scenario.

Exchange of tears under a contact lens is driven by distortions of the contact lens.

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Maki, Kara L; Ross, David S

2014-12-01

We studied the flow of the post-lens tear film under a soft contact lens to understand how the design parameters of contact lenses can affect ocular health. When a soft contact lens is inserted, the blinking eyelid causes the lens to stretch in order to conform to the shape of the eye. The deformed contact lens acts to assume its un-deformed shape and thus generates a suction pressure in the post-lens tear film. In consequence, the post-lens tear fluid moves; it responds to the suction pressure. The suction pressure may draw in fresh fluid from the edge of the lens, or it may eject fluid there, as the lens reassumes its un-deformed shape. In this article, we develop a mathematical model of the flow of the post-lens tear fluid in response to the mechanical suction pressure of a deformed contact lens. We predict the amount of exchange of fluid exchange under a contact lens and we explore the influence of the eye's shape on the rate of exchange of fluid. © The Author 2014. 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.

Scaling laws for file dissemination in P2P networks with random contacts

NARCIS (Netherlands)

Nunez-Queija, R.; Prabhu, B.

2008-01-01

In this paper we obtain the scaling law for the mean broadcast time of a file in a P2P network with an initial population of N nodes. In the model, at Poisson rate λ a node initiates a contact with another node chosen uniformly at random. This contact is said to be successful if the contacted node

Scaling laws for file dissemination in P2P networks with random contacts

NARCIS (Netherlands)

Núñez-Queija, R.; Prabhu, B.

2008-01-01

In this paper we obtain the scaling law for the mean broadcast time of a file in a P2P network with an initial population of N nodes. In the model, at Poisson rate lambda a node initiates a contact with another node chosen uniformly at random. This contact is said to be successful if the contacted

A multilevel path analysis of contact frequency between social network members

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van den Berg, Pauline; Arentze, Theo; Timmermans, Harry

2012-04-01

Recently, there has been an increasing interest in the role of social networks in spatial-choice and travel behavior. It has been acknowledged that social activities and the travel for these activities can emerge from individuals' social networks and that social activities are responsible for an important portion of travel demand. The influence of information and communication technologies (ICT's) is also important in this respect. The purpose of the paper is to examine the effects of characteristics of egos and ego-alter relationships on the frequency of social interaction by different communication modes, using multilevel path analysis. The analyses are based on social network data collected in 2008 in the Eindhoven region in the Netherlands among 116 respondents. The results indicate a complementary relationship between contact frequencies by different modes. The contact frequencies of the different modes, especially face-to-face and telephone, can also be largely explained by the ego's personal characteristics and the type of relationship and the distance between ego and alter.

How to Estimate Epidemic Risk from Incomplete Contact Diaries Data?

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Mastrandrea, Rossana; Barrat, Alain

2016-06-01

Social interactions shape the patterns of spreading processes in a population. Techniques such as diaries or proximity sensors allow to collect data about encounters and to build networks of contacts between individuals. The contact networks obtained from these different techniques are however quantitatively different. Here, we first show how these discrepancies affect the prediction of the epidemic risk when these data are fed to numerical models of epidemic spread: low participation rate, under-reporting of contacts and overestimation of contact durations in contact diaries with respect to sensor data determine indeed important differences in the outcomes of the corresponding simulations with for instance an enhanced sensitivity to initial conditions. Most importantly, we investigate if and how information gathered from contact diaries can be used in such simulations in order to yield an accurate description of the epidemic risk, assuming that data from sensors represent the ground truth. The contact networks built from contact sensors and diaries present indeed several structural similarities: this suggests the possibility to construct, using only the contact diary network information, a surrogate contact network such that simulations using this surrogate network give the same estimation of the epidemic risk as simulations using the contact sensor network. We present and compare several methods to build such surrogate data, and show that it is indeed possible to obtain a good agreement between the outcomes of simulations using surrogate and sensor data, as long as the contact diary information is complemented by publicly available data describing the heterogeneity of the durations of human contacts.

Diagnosis of constant faults in read-once contact networks over finite bases

KAUST Repository

Busbait, Monther I.; Chikalov, Igor; Hussain, Shahid; Moshkov, Mikhail

2015-01-01

We study the depth of decision trees for diagnosis of constant 0 and 1 faults in read-once contact networks over finite bases containing only indecomposable networks. For each basis, we obtain a linear upper bound on the minimum depth of decision trees depending on the number of edges in the networks. For bases containing networks with at most 10 edges we find coefficients for linear bounds which are close to sharp. © 2014 Elsevier B.V. All rights reserved.

Diagnosis of constant faults in read-once contact networks over finite bases

KAUST Repository

Busbait, Monther I.

2015-03-01

We study the depth of decision trees for diagnosis of constant 0 and 1 faults in read-once contact networks over finite bases containing only indecomposable networks. For each basis, we obtain a linear upper bound on the minimum depth of decision trees depending on the number of edges in the networks. For bases containing networks with at most 10 edges we find coefficients for linear bounds which are close to sharp. © 2014 Elsevier B.V. All rights reserved.

Critical behavior of the contact process on small-world networks

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Ferreira, Ronan S.; Ferreira, Silvio C.

2013-11-01

We investigate the role of clustering on the critical behavior of the contact process (CP) on small-world networks using the Watts-Strogatz (WS) network model with an edge rewiring probability p. The critical point is well predicted by a homogeneous cluster-approximation for the limit of vanishing clustering ( p → 1). The critical exponents and dimensionless moment ratios of the CP are in agreement with those predicted by the mean-field theory for any p > 0. This independence on the network clustering shows that the small-world property is a sufficient condition for the mean-field theory to correctly predict the universality of the model. Moreover, we compare the CP dynamics on WS networks with rewiring probability p = 1 and random regular networks and show that the weak heterogeneity of the WS network slightly changes the critical point but does not alter other critical quantities of the model.

Competing Contact Processes on Homogeneous Networks with Tunable Clusterization

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Rybak, Marcin; Kułakowski, Krzysztof

2013-03-01

We investigate two homogeneous networks: the Watts-Strogatz network with mean degree ⟨k⟩ = 4 and the Erdös-Rényi network with ⟨k⟩ = 10. In both kinds of networks, the clustering coefficient C is a tunable control parameter. The network is an area of two competing contact processes, where nodes can be in two states, S or D. A node S becomes D with probability 1 if at least two its mutually linked neighbors are D. A node D becomes S with a given probability p if at least one of its neighbors is S. The competition between the processes is described by a phase diagram, where the critical probability pc depends on the clustering coefficient C. For p > pc the rate of state S increases in time, seemingly to dominate in the whole system. Below pc, the majority of nodes is in the D-state. The numerical results indicate that for the Watts-Strogatz network the D-process is activated at the finite value of the clustering coefficient C, close to 0.3. On the contrary, for the Erdös-Rényi network the transition is observed at the whole investigated range of C.

Social Networking Sites and Contact Risks among Flemish Youth

Science.gov (United States)

Vandoninck, Sofie; d'Haenens, Leen; De Cock, Rozane; Donoso, Veronica

2012-01-01

This study investigates how teenagers use social networking sites (SNS) and other online communication applications, to what extent they are exposed to online contact risks related to the use of these online tools and how they cope with these risks. A written survey was administered among 815 Flemish adolescents aged 14-19. The study controls for…

GH32 family activity: a topological approach through protein contact networks.

Science.gov (United States)

Cimini, Sara; Di Paola, Luisa; Giuliani, Alessandro; Ridolfi, Alessandra; De Gara, Laura

2016-11-01

The application of Protein Contact Networks methodology allowed to highlight a novel response of border region between the two domains to substrate binding. Glycoside hydrolases (GH) are enzymes that mainly hydrolyze the glycosidic bond between two carbohydrates or a carbohydrate and a non-carbohydrate moiety. These enzymes are involved in many fundamental and diverse biological processes in plants. We have focused on the GH32 family, including enzymes very similar in both sequence and structure, each having however clear specificities of substrate preferences and kinetic properties. Structural and topological differences among proteins of the GH32 family have been here identified by means of an emerging approach (Protein Contact network, PCN) based on the formalization of 3D structures as contact networks among amino-acid residues. The PCN approach proved successful in both reconstructing the already known functional domains and in identifying the structural counterpart of the properties of GH32 enzymes, which remain uncertain, like their allosteric character. The main outcome of the study was the discovery of the activation upon binding of the border (cleft) region between the two domains. This reveals the allosteric nature of the enzymatic activity for all the analyzed forms in the GH32 family, a character yet to be highlighted in biochemical studies. Furthermore, we have been able to recognize a topological signature (graph energy) of the different affinity of the enzymes towards small and large substrates.

Diminution of contact angle hysteresis under the influence of an oscillating force.

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Manor, Ofer

2014-06-17

We suggest a simple quantitative model for the diminution of contact angle hysteresis under the influence of an oscillatory force invoked by thermal fluctuations, substrate vibrations, acoustic waves, or oscillating electric fields. Employing force balance rather than the usual description of contact angle hysteresis in terms of Gibbs energy, we highlight that a wetting system, such as a sessile drop or a bubble adhered to a solid substrate, appears at long times to be partially or fully independent of contact angle hysteresis and thus independent of static friction forces, as a result of contact line pinning. We verify this theory by studying several well-known experimental observations such as the approach of an arbitrary contact angle toward the Young contact angle and the apparent decrease (or increase) in an advancing (or a receding) contact angle under the influence of an external oscillating force.

Critical behavior of the contact process in a multiscale network

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Ferreira, Silvio C.; Martins, Marcelo L.

2007-09-01

Inspired by dengue and yellow fever epidemics, we investigated the contact process (CP) in a multiscale network constituted by one-dimensional chains connected through a Barabási-Albert scale-free network. In addition to the CP dynamics inside the chains, the exchange of individuals between connected chains (travels) occurs at a constant rate. A finite epidemic threshold and an epidemic mean lifetime diverging exponentially in the subcritical phase, concomitantly with a power law divergence of the outbreak’s duration, were found. A generalized scaling function involving both regular and SF components was proposed for the quasistationary analysis and the associated critical exponents determined, demonstrating that the CP on this hybrid network and nonvanishing travel rates establishes a new universality class.

An Investigation of a New Social Networks Contact Suggestion Based on Face Recognition Algorithm

Directory of Open Access Journals (Sweden)

Ivan Zelinka

2016-01-01

Full Text Available Automated comparison of faces in the photographs is a well established discipline. The main aim of this paper is to describe an approach whereby face recognition can be used in suggestion of a new contacts. The new contact suggestion is a common technique used across all main social networks. Our approach uses a freely available face comparison called "Betaface" together with our automated processig of the user´s Facebook profile. The research´s main point of interest is the comparison of friend´s facial images in a social network itself, how to process such a great amount of photos and what additional sources of data should be used. In this approach we used our automated processing algorithm Betaface in the social network Facebook and for the additional data, the Flickr social network was used. The results and their quality are discussed at the end.

Study on the fatigue crack initiation life under spherical contact

Energy Technology Data Exchange (ETDEWEB)

Cho, Yong Joo; Kim, Tae Wan [Busan National Univ., Busan (Korea, Republic of); Lee, Mun Ju [Samsung Electronics Co., Ltd., Suwon (Korea, Republic of)

2001-08-01

In case of contact fatigue, the accurate calculation of surface tractions and subsurface stress is essential to the prediction of crack initiation life. Surface tractions influencing shear stress amplitude have been obtained by contact analysis based on influence function. Subsurface stress has been obtained by using rectangular patch solutions. In this study, to simulate asperity contact under sliding condition, the tip of asperity was simulated by sphere and to calculate crack initiation life in the substrate, dislocation pileup theory was used.

Study on the fatigue crack initiation life under spherical contact

International Nuclear Information System (INIS)

Cho, Yong Joo; Kim, Tae Wan; Lee, Mun Ju

2001-01-01

In case of contact fatigue, the accurate calculation of surface tractions and subsurface stress is essential to the prediction of crack initiation life. Surface tractions influencing shear stress amplitude have been obtained by contact analysis based on influence function. Subsurface stress has been obtained by using rectangular patch solutions. In this study, to simulate asperity contact under sliding condition, the tip of asperity was simulated by sphere and to calculate crack initiation life in the substrate, dislocation pileup theory was used

Diagnosis of three types of constant faults in read-once contact networks over finite bases

KAUST Repository

Busbait, Monther I.; Moshkov, Mikhail

2016-01-01

We study the depth of decision trees for diagnosis of three types of constant faults in read-once contact networks over finite bases containing only indecomposable networks. For each basis and each type of faults, we obtain a linear upper bound

Simulations of biopolymer networks under shear

NARCIS (Netherlands)

Huisman, Elisabeth Margaretha

2011-01-01

In this thesis we present a new method to simulate realistic three-dimensional networks of biopolymers under shear. These biopolymer networks are important for the structural functions of cells and tissues. We use the method to analyze these networks under shear, and consider the elastic modulus,

Magnitude and Spatial Distribution of Impact Intensity Under the Foot Relates to Initial Foot Contact Pattern.

Science.gov (United States)

Breine, Bastiaan; Malcolm, Philippe; Segers, Veerle; Gerlo, Joeri; Derie, Rud; Pataky, Todd; Frederick, Edward C; De Clercq, Dirk

2017-12-01

In running, foot contact patterns (rear-, mid-, or forefoot contact) influence impact intensity and initial ankle and foot kinematics. The aim of the study was to compare impact intensity and its spatial distribution under the foot between different foot contact patterns. Forty-nine subjects ran at 3.2 m·s -1 over a level runway while ground reaction forces (GRF) and shoe-surface pressures were recorded and foot contact pattern was determined. A 4-zone footmask (forefoot, midfoot, medial and lateral rearfoot) assessed the spatial distribution of the vertical GRF under the foot. We calculated peak vertical instantaneous loading rate of the GRF (VILR) per foot zone as the impact intensity measure. Midfoot contact patterns were shown to have the lowest, and atypical rearfoot contact patterns the highest impact intensities, respectively. The greatest local impact intensity was mainly situated under the rear- and midfoot for the typical rearfoot contact patterns, under the midfoot for the atypical rearfoot contact patterns, and under the mid- and forefoot for the midfoot contact patterns. These findings indicate that different foot contact patterns could benefit from cushioning in different shoe zones.

Social buffering and contact transmission: network connections have beneficial and detrimental effects on Shigella infection risk among captive rhesus macaques

Directory of Open Access Journals (Sweden)

Krishna Balasubramaniam

2016-10-01

Full Text Available In social animals, group living may impact the risk of infectious disease acquisition in two ways. On the one hand, social connectedness puts individuals at greater risk or susceptibility for acquiring enteric pathogens via contact-mediated transmission. Yet conversely, in strongly bonded societies like humans and some nonhuman primates, having close connections and strong social ties of support can also socially buffer individuals against susceptibility or transmissibility of infectious agents. Using social network analyses, we assessed the potentially competing roles of contact-mediated transmission and social buffering on the risk of infection from an enteric bacterial pathogen (Shigella flexneri among captive groups of rhesus macaques (Macaca mulatta. Our results indicate that, within two macaque groups, individuals possessing more direct and especially indirect connections in their grooming and huddling social networks were less susceptible to infection. These results are in sharp contrast to several previous studies that indicate that increased (direct contact-mediated transmission facilitates infectious disease transmission, including our own findings in a third macaque group in which individuals central in their huddling network and/or which initiated more fights were more likely to be infected. In summary, our findings reveal that an individual’s social connections may increase or decrease its chances of acquiring infectious agents. They extend the applicability of the social buffering hypothesis, beyond just stress and immune-function-related health benefits, to the additional health outcome of infectious disease resistance. Finally, we speculate that the circumstances under which social buffering versus contact-mediated transmission may occur could depend on multiple factors, such as living condition, pathogen-specific transmission routes, and/or an overall social context such as a group’s social stability.

Diagnosis of three types of constant faults in read-once contact networks over finite bases

KAUST Repository

Busbait, Monther I.

2016-03-24

We study the depth of decision trees for diagnosis of three types of constant faults in read-once contact networks over finite bases containing only indecomposable networks. For each basis and each type of faults, we obtain a linear upper bound on the minimum depth of decision trees depending on the number of edges in networks. For bases containing networks with at most 10 edges, we find sharp coefficients for linear bounds.

Non-Contact Plant Growth Measurement Method and System Based on Ubiquitous Sensor Network Technologies

Directory of Open Access Journals (Sweden)

Intae Ryoo

2011-04-01

Full Text Available This paper proposes a non-contact plant growth measurement system using infrared sensors based on the ubiquitous sensor network (USN technology. The proposed system measures plant growth parameters such as the stem radius of plants using real-time non-contact methods, and generates diameter, cross-sectional area and thickening form of plant stems using this measured data. Non-contact sensors have been used not to cause any damage to plants during measurement of the growth parameters. Once the growth parameters are measured, they are transmitted to a remote server using the sensor network technology and analyzed in the application program server. The analyzed data are then provided for administrators and a group of interested users. The proposed plant growth measurement system has been designed and implemented using fixed-type and rotary-type infrared sensor based measurement methods and devices. Finally, the system performance is compared and verified with the measurement data that have been obtained by practical field experiments.

Hand hygiene compliance in patients under contact precautions and in the general hospital population.

Science.gov (United States)

Almaguer-Leyva, Martín; Mendoza-Flores, Lidia; Medina-Torres, Ana Gabriela; Salinas-Caballero, Ana Gabriela; Vidaña-Amaro, Jose Antonio; Garza-Gonzalez, Elvira; Camacho-Ortiz, Adrián

2013-11-01

Hand hygiene (HH) is the single most important intervention for preventing hospital-acquired infections. Contact precautions are a series of actions that infection control units take to reduce the transmission of nosocomial pathogens. We conducted an observational study of HH compliance. Observations were stratified as opportunities in patients under contact precautions and in the general hospital population. Trained infection control personnel performed all direct evaluations. A total of 3,270 opportunities were recorded. HH compliance was statistically higher in patients on contact precautions than in the overall population (70.3% vs 60.4%; P = .0001). Critical care areas had higher HH compliance when patients were isolated by contact precautions. Medical wards were statistically lower in HH when patients were under contact precautions. Respiratory technicians had the highest HH compliance in both overall performance and in patients under contact precautions. Medical students had a lower HH compliance in both evaluations (P Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

DNCON2: improved protein contact prediction using two-level deep convolutional neural networks.

Science.gov (United States)

Adhikari, Badri; Hou, Jie; Cheng, Jianlin

2018-05-01

Significant improvements in the prediction of protein residue-residue contacts are observed in the recent years. These contacts, predicted using a variety of coevolution-based and machine learning methods, are the key contributors to the recent progress in ab initio protein structure prediction, as demonstrated in the recent CASP experiments. Continuing the development of new methods to reliably predict contact maps is essential to further improve ab initio structure prediction. In this paper we discuss DNCON2, an improved protein contact map predictor based on two-level deep convolutional neural networks. It consists of six convolutional neural networks-the first five predict contacts at 6, 7.5, 8, 8.5 and 10 Å distance thresholds, and the last one uses these five predictions as additional features to predict final contact maps. On the free-modeling datasets in CASP10, 11 and 12 experiments, DNCON2 achieves mean precisions of 35, 50 and 53.4%, respectively, higher than 30.6% by MetaPSICOV on CASP10 dataset, 34% by MetaPSICOV on CASP11 dataset and 46.3% by Raptor-X on CASP12 dataset, when top L/5 long-range contacts are evaluated. We attribute the improved performance of DNCON2 to the inclusion of short- and medium-range contacts into training, two-level approach to prediction, use of the state-of-the-art optimization and activation functions, and a novel deep learning architecture that allows each filter in a convolutional layer to access all the input features of a protein of arbitrary length. The web server of DNCON2 is at http://sysbio.rnet.missouri.edu/dncon2/ where training and testing datasets as well as the predictions for CASP10, 11 and 12 free-modeling datasets can also be downloaded. Its source code is available at https://github.com/multicom-toolbox/DNCON2/. chengji@missouri.edu. Supplementary data are available at Bioinformatics online.

Mechanical properties of cork under contact stresses

International Nuclear Information System (INIS)

Parralejo, A. D.; Guiberteau, F.; Fortes, M. A.; Rosa, M. E.

2001-01-01

In this work our interest is focussed on the mechanical behaviour of natural cork under contact stresses. Many of the applications of this curious material are related with its mechanical response under such a stress field, however this topic has not been still sufficiently considered in the scientific literature. For this purpose, we proposed the use of Hertzian indentation tests. By using this mythology we have investigated the cork structure influence on the corresponding mechanical properties. Our results reveal a clear mechanical anisotropy effect. Moreover, the elastic modulus corresponding to specific directions have been estimated. Several are the main advantages of this specific test mythology versus traditional uniaxial compression tests, specially simplicity and local character. (Author) 9 refs

A General Contact Force Analysis of an Under-Actuated Finger in Robot Hand Grasping

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Xuan Vinh Ha

2016-02-01

Full Text Available This paper develops a mathematical analysis of contact forces for the under-actuated finger in a general under-actuated robotic hand during grasping. The concept of under-actuation in robotic grasping with fewer actuators than degrees of freedom (DOF, through the use of springs and mechanical limits, allows the hand to adjust itself to an irregularly shaped object without complex control strategies and sensors. Here the main concern is the contact forces, which are important elements in grasping tasks, based on the proposed mathematical analysis of their distributions of the n-DOF under-actuated finger. The simulation results, along with the 3-DOF finger from the ADAMS model, show the effectiveness of the mathematical analysis method, while comparing them with the measured results. The system can find magnitudes of the contact forces at the contact positions between the phalanges and the object.

Wildlife contact analysis: Emerging methods, questions, and challenges

Science.gov (United States)

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.

An individual-based approach to SIR epidemics in contact networks.

Science.gov (United States)

Youssef, Mina; Scoglio, Caterina

2011-08-21

Many approaches have recently been proposed to model the spread of epidemics on networks. For instance, the Susceptible/Infected/Recovered (SIR) compartmental model has successfully been applied to different types of diseases that spread out among humans and animals. When this model is applied on a contact network, the centrality characteristics of the network plays an important role in the spreading process. However, current approaches only consider an aggregate representation of the network structure, which can result in inaccurate analysis. In this paper, we propose a new individual-based SIR approach, which considers the whole description of the network structure. The individual-based approach is built on a continuous time Markov chain, and it is capable of evaluating the state probability for every individual in the network. Through mathematical analysis, we rigorously confirm the existence of an epidemic threshold below which an epidemic does not propagate in the network. We also show that the epidemic threshold is inversely proportional to the maximum eigenvalue of the network. Additionally, we study the role of the whole spectrum of the network, and determine the relationship between the maximum number of infected individuals and the set of eigenvalues and eigenvectors. To validate our approach, we analytically study the deviation with respect to the continuous time Markov chain model, and we show that the new approach is accurate for a large range of infection strength. Furthermore, we compare the new approach with the well-known heterogeneous mean field approach in the literature. Ultimately, we support our theoretical results through extensive numerical evaluations and Monte Carlo simulations. Published by Elsevier Ltd.

Growth of contact area between rough surfaces under normal stress

Science.gov (United States)

Stesky, R. M.; Hannan, S. S.

1987-05-01

The contact area between deforming rough surfaces in marble, alabaster, and quartz was measured from thin sections of surfaces bonded under load with low viscosity resin epoxy. The marble and alabaster samples had contact areas that increased with stress at an accelerating rate. This result suggests that the strength of the asperity contacts decreased progressively during the deformation, following some form of strain weakening relationship. This conclusion is supported by petrographic observation of the thin sections that indicate that much of the deformation was cataclastic, with minor twinning of calcite and kinking of gypsum. In the case of the quartz, the observed contact area was small and increased approximately linearly with normal stress. Only the irreversible cataclastic deformation was observed; however strain-induced birefringence and cracking of the epoxy, not observed with the other rocks, suggests that significant elastic deformation occurred, but recovered during unloading.

Robust microscale superlubricity under high contact pressure enabled by graphene-coated microsphere

Science.gov (United States)

Liu, Shu-Wei; Wang, Hua-Ping; Xu, Qiang; Ma, Tian-Bao; Yu, Gui; Zhang, Chenhui; Geng, Dechao; Yu, Zhiwei; Zhang, Shengguang; Wang, Wenzhong; Hu, Yuan-Zhong; Wang, Hui; Luo, Jianbin

2017-02-01

Superlubricity of graphite and graphene has aroused increasing interest in recent years. Yet how to obtain a long-lasting superlubricity between graphene layers, under high applied normal load in ambient atmosphere still remains a challenge but is highly desirable. Here, we report a direct measurement of sliding friction between graphene and graphene, and graphene and hexagonal boron nitride (h-BN) under high contact pressures by employing graphene-coated microsphere (GMS) probe prepared by metal-catalyst-free chemical vapour deposition. The exceptionally low and robust friction coefficient of 0.003 is accomplished under local asperity contact pressure up to 1 GPa, at arbitrary relative surface rotation angles, which is insensitive to relative humidity up to 51% RH. This ultralow friction is attributed to the sustainable overall incommensurability due to the multi-asperity contact covered with randomly oriented graphene nanograins. This realization of microscale superlubricity can be extended to the sliding between a variety of two-dimensional (2D) layers.

The masonry behaviour under contact detonation

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Marin Lupoae

2017-03-01

Full Text Available Breaching in masonry wall as a process of quick intervention of special forces in emergency cases, may require the use of explosive charges. In order to maximize the explosive effects on the wall and to minimize the shock wave and fragments propulsion, such breaching systems usually use a water layer which cover the explosive charge. The thickness of the water layer has a significant influence both on the mitigation of unwanted effects and enhancing the demolition effect, but also increases the mass of the system which can have negative consequences on the maneuverability and rapidity of intervention, respectivly. In this respect, the paper under consideration addresses numerical and experimental research on masonry walls to determine the behavior of mortar and brick under contact detonation and to establish an optimal water layer thickness to balance the breaching system requirement related to the mass on the one hand and effects and offered protection on the other hand.

Characterization of contact structures for the spread of infectious diseases in a pork supply chain in northern Germany by dynamic network analysis of yearly and monthly networks.

Science.gov (United States)

Büttner, K; Krieter, J; Traulsen, I

2015-04-01

A major risk factor in the spread of diseases between holdings is the transport of live animals. This study analysed the animal movements of the pork supply chain of a producer group in Northern Germany. The parameters in-degree and out-degree, ingoing and outgoing infection chain, betweenness and ingoing and outgoing closeness were measured using dynamic network analysis to identify holdings with central positions in the network and to characterize the overall network topology. The potential maximum epidemic size was also estimated. All parameters were calculated for three time periods: the 3-yearly network, the yearly and the monthly networks. The yearly and the monthly networks were more fragmented than the 3-yearly network. On average, one-third of the holdings were isolated in the yearly networks and almost three quarters in the monthly networks. This represented an immense reduction in the number of holdings participating in the trade of the monthly networks. The overall network topology showed right-skewed distributions for all calculated centrality parameters indicating that network resilience was high concerning the random removal of holdings. However, for a targeted removal of holdings according to their centrality, a rapid fragmentation of the trade network could be expected. Furthermore, to capture the real importance of holdings for disease transmission, indirect trade contacts (infection chain) should be considered. In contrast to the parameters regarding direct trade contacts (degree), the infection chain parameter did not underestimate the potential risk of disease transmission. This became more obvious, the longer the observed time period was. For all three time periods, the results for the estimation of the potential maximum epidemic size illustrated that the outgoing infection chain should be chosen. It considers the chronological order and the directed nature of the contacts and has no restrictions such as the strongly connected components of a

Social networks and getting a home : Do contacts matter?

NARCIS (Netherlands)

Röper, A.; Völker, B.G.M.; Flap, H.D.

2009-01-01

Under what conditions does one find a newhome via one’s social network? Does theway in which a house is acquired affect how satisfied one is with the house? We formulate hypotheses on the characteristics of personal networks, the context of the move and their effect on those who attain a house

Epidemic spreading in annealed directed networks: susceptible-infected-susceptible model and contact process.

Science.gov (United States)

Kwon, Sungchul; Kim, Yup

2013-01-01

We investigate epidemic spreading in annealed directed scale-free networks with the in-degree (k) distribution P(in)(k)~k(-γ(in)) and the out-degree (ℓ) distribution, P(out)(ℓ)~ℓ(-γ(out)). The correlation of each node on the networks is controlled by the probability r(0≤r≤1) in two different algorithms, the so-called k and ℓ algorithms. For r=1, the k algorithm gives =, whereas the ℓ algorithm gives =. For r=0, = for both algorithms. As the prototype of epidemic spreading, the susceptible-infected-susceptible model and contact process on the networks are analyzed using the heterogeneous mean-field theory and Monte Carlo simulations. The directedness of links and the correlation of the network are found to play important roles in the spreading, so that critical behaviors of both models are distinct from those on undirected scale-free networks.

Sensitivity enhancement by multiple-contact cross-polarization under magic-angle spinning.

Science.gov (United States)

Raya, J; Hirschinger, J

2017-08-01

Multiple-contact cross-polarization (MC-CP) is applied to powder samples of ferrocene and l-alanine under magic-angle spinning (MAS) conditions. The method is described analytically through the density matrix formalism. The combination of a two-step memory function approach and the Anderson-Weiss approximation is found to be particularly useful to derive approximate analytical solutions for single-contact Hartmann-Hahn CP (HHCP) and MC-CP dynamics under MAS. We show that the MC-CP sequence requiring no pulse-shape optimization yields higher polarizations at short contact times than optimized adiabatic passage through the HH condition CP (APHH-CP) when the MAS frequency is comparable to the heteronuclear dipolar coupling, i.e., when APHH-CP through a single sideband matching condition is impossible or difficult to perform. It is also shown that the MC-CP sideband HH conditions are generally much broader than for single-contact HHCP and that efficient polarization transfer at the centerband HH condition can be reintroduced by rotor-asynchronous multiple equilibrations-re-equilibrations with the proton spin bath. Boundary conditions for the successful use of the MC-CP experiment when relying on spin-lattice relaxation for repolarization are also examined. Copyright © 2017 Elsevier Inc. All rights reserved.

Interacting epidemics and coinfection on contact networks.

Science.gov (United States)

Newman, M E J; Ferrario, Carrie R

2013-01-01

The spread of certain diseases can be promoted, in some cases substantially, by prior infection with another disease. One example is that of HIV, whose immunosuppressant effects significantly increase the chances of infection with other pathogens. Such coinfection processes, when combined with nontrivial structure in the contact networks over which diseases spread, can lead to complex patterns of epidemiological behavior. Here we consider a mathematical model of two diseases spreading through a single population, where infection with one disease is dependent on prior infection with the other. We solve exactly for the sizes of the outbreaks of both diseases in the limit of large population size, along with the complete phase diagram of the system. Among other things, we use our model to demonstrate how diseases can be controlled not only by reducing the rate of their spread, but also by reducing the spread of other infections upon which they depend.

Competing contact processes in the Watts-Strogatz network

Science.gov (United States)

Rybak, Marcin; Malarz, Krzysztof; Kułakowski, Krzysztof

2016-06-01

We investigate two competing contact processes on a set of Watts-Strogatz networks with the clustering coefficient tuned by rewiring. The base for network construction is one-dimensional chain of N sites, where each site i is directly linked to nodes labelled as i ± 1 and i ± 2. So initially, each node has the same degree k i = 4. The periodic boundary conditions are assumed as well. For each node i the links to sites i + 1 and i + 2 are rewired to two randomly selected nodes so far not-connected to node i. An increase of the rewiring probability q influences the nodes degree distribution and the network clusterization coefficient 𝓒. For given values of rewiring probability q the set 𝓝(q)={𝓝1,𝓝2,...,𝓝 M } of M networks is generated. The network's nodes are decorated with spin-like variables s i ∈ { S,D }. During simulation each S node having a D-site in its neighbourhood converts this neighbour from D to S state. Conversely, a node in D state having at least one neighbour also in state D-state converts all nearest-neighbours of this pair into D-state. The latter is realized with probability p. We plot the dependence of the nodes S final density n S T on initial nodes S fraction n S 0. Then, we construct the surface of the unstable fixed points in (𝓒, p, n S 0) space. The system evolves more often toward n S T for (𝓒, p, n S 0) points situated above this surface while starting simulation with (𝓒, p, n S 0) parameters situated below this surface leads system to n S T =0. The points on this surface correspond to such value of initial fraction n S * of S nodes (for fixed values 𝓒 and p) for which their final density is n S T=1/2.

Nonlinear Equilibrium and Stability Analysis of Axially Loaded Piles Under Bilateral Contact Constraints

Directory of Open Access Journals (Sweden)

Ricardo A. da Mota Silveira

Full Text Available AbstractThis paper presents a nonlinear stability analysis of piles under bilateral contact constraints imposed by a geological medium (soil or rock. To solve this contact problem, the paper proposes a general numerical methodology, based on the finite element method (FEM. In this context, a geometrically nonlinear beam-column element is used to model the pile while the geological medium can be idealized as discrete (spring or continuum (Winkler and Pasternak foundation elements. Foundation elements are supposed to react under tension and compression, so during the deformation process the structural elements are subjected to bilateral contact constraints. The errors along the equilibrium paths are minimized and the convoluted nonlinear equilibrium paths are made traceable through the use of an updated Lagrangian formulation and a Newton-Raphson scheme working with the generalized displacement technique. The study offers stability analyses of three problems involving piles under bilateral contact constraints. The analyses show that in the evaluation of critical loads a great influence is wielded by the instability modes. Also, the structural system stiffness can be highly influenced by the representative model of the soil.

Epidemic contact tracing via communication traces.

Directory of Open Access Journals (Sweden)

Katayoun Farrahi

Full Text Available Traditional contact tracing relies on knowledge of the interpersonal network of physical interactions, where contagious outbreaks propagate. However, due to privacy constraints and noisy data assimilation, this network is generally difficult to reconstruct accurately. Communication traces obtained by mobile phones are known to be good proxies for the physical interaction network, and they may provide a valuable tool for contact tracing. Motivated by this assumption, we propose a model for contact tracing, where an infection is spreading in the physical interpersonal network, which can never be fully recovered; and contact tracing is occurring in a communication network which acts as a proxy for the first. We apply this dual model to a dataset covering 72 students over a 9 month period, for which both the physical interactions as well as the mobile communication traces are known. Our results suggest that a wide range of contact tracing strategies may significantly reduce the final size of the epidemic, by mainly affecting its peak of incidence. However, we find that for low overlap between the face-to-face and communication interaction network, contact tracing is only efficient at the beginning of the outbreak, due to rapidly increasing costs as the epidemic evolves. Overall, contact tracing via mobile phone communication traces may be a viable option to arrest contagious outbreaks.

Epidemic contact tracing via communication traces.

Science.gov (United States)

Farrahi, Katayoun; Emonet, Rémi; Cebrian, Manuel

2014-01-01

Traditional contact tracing relies on knowledge of the interpersonal network of physical interactions, where contagious outbreaks propagate. However, due to privacy constraints and noisy data assimilation, this network is generally difficult to reconstruct accurately. Communication traces obtained by mobile phones are known to be good proxies for the physical interaction network, and they may provide a valuable tool for contact tracing. Motivated by this assumption, we propose a model for contact tracing, where an infection is spreading in the physical interpersonal network, which can never be fully recovered; and contact tracing is occurring in a communication network which acts as a proxy for the first. We apply this dual model to a dataset covering 72 students over a 9 month period, for which both the physical interactions as well as the mobile communication traces are known. Our results suggest that a wide range of contact tracing strategies may significantly reduce the final size of the epidemic, by mainly affecting its peak of incidence. However, we find that for low overlap between the face-to-face and communication interaction network, contact tracing is only efficient at the beginning of the outbreak, due to rapidly increasing costs as the epidemic evolves. Overall, contact tracing via mobile phone communication traces may be a viable option to arrest contagious outbreaks.

Contact force and mechanical loss of multistage cable under tension and bending

Science.gov (United States)

Ru, Yanyun; Yong, Huadong; Zhou, Youhe

2016-10-01

A theoretical model for calculating the stress and strain states of cabling structures with different loadings has been developed in this paper. We solve the problem for the first- and second-stage cable with tensile or bending strain. The contact and friction forces between the strands are presented by two-dimensional contact model. Several theoretical models have been proposed to verify the results when the triplet subjected to the tensile strain, including contact force, contact stresses, and mechanical loss. It is found that loadings will affect the friction force and the mechanical loss of the triplet. The results show that the contact force and mechanical loss are dependent on the twist pitch. A shorter twist pitch can lead to higher contact force, while the trend of mechanical loss with twist pitch is complicated. The mechanical loss may be reduced by adjusting the twist pitch reasonably. The present model provides a simple analysis method to investigate the mechanical behaviors in multistage-structures under different loads.

Strategies for optical transport network recovery under epidemic network failures

DEFF Research Database (Denmark)

Ruepp, Sarah Renée; Fagertun, Anna Manolova; Kosteas, Vasileios

2015-01-01

The current trend in deploying automatic control plane solutions for increased flexibility in the optical transport layer leads to numerous advantages for both the operators and the customers, but also pose challenges related to the stability of the network and its ability to operate in a robust...... manner under different failure scenarios. This work evaluates two rerouting strategies and proposes four policies for failure handling in a connection-oriented optical transport network, under generalized multiprotocol label switching control plane. The performance of the strategies and the policies......, and that there exist a clear trade-off between policy performance and network resource consumption, which must be addressed by network operators for improved robustness of their transport infrastructures. Applying proactive methods for avoiding areas where epidemic failures spread results in 50% less connections...

Application Of Artificial Neural Networks In Modeling Of Manufactured Front Metallization Contact Resistance For Silicon Solar Cells

Directory of Open Access Journals (Sweden)

Musztyfaga-Staszuk M.

2015-09-01

Full Text Available This paper presents the application of artificial neural networks for prediction contact resistance of front metallization for silicon solar cells. The influence of the obtained front electrode features on electrical properties of solar cells was estimated. The front electrode of photovoltaic cells was deposited using screen printing (SP method and next to manufactured by two methods: convectional (1. co-fired in an infrared belt furnace and unconventional (2. Selective Laser Sintering. Resistance of front electrodes solar cells was investigated using Transmission Line Model (TLM. Artificial neural networks were obtained with the use of Statistica Neural Network by Statsoft. Created artificial neural networks makes possible the easy modelling of contact resistance of manufactured front metallization and allows the better selection of production parameters. The following technological recommendations for the screen printing connected with co-firing and selective laser sintering technology such as optimal paste composition, morphology of the silicon substrate, co-firing temperature and the power and scanning speed of the laser beam to manufacture the front electrode of silicon solar cells were experimentally selected in order to obtain uniformly melted structure well adhered to substrate, of a small front electrode substrate joint resistance value. The prediction possibility of contact resistance of manufactured front metallization is valuable for manufacturers and constructors. It allows preserving the customers’ quality requirements and bringing also measurable financial advantages.

Interspecific Competition Underlying Mutualistic Networks

Science.gov (United States)

Maeng, Seong Eun; Lee, Jae Woo; Lee, Deok-Sun

2012-03-01

Multiple classes of interactions may exist affecting one another in a given system. For the mutualistic networks of plants and pollinating animals, it has been known that the degree distribution is broad but often deviates from power-law form more significantly for plants than animals. To illuminate the origin of such asymmetry, we study a model network in which links are assigned under generalized preferential-selection rules between two groups of nodes and find the sensitive dependence of the resulting connectivity pattern on the model parameters. The nonlinearity of preferential selection can come from interspecific interactions among animals and among plants. The model-based analysis of real-world mutualistic networks suggests that a new animal determines its partners not only by their abundance but also under the competition with existing animal species, which leads to the stretched-exponential degree distributions of plants.

Adhesive Wear Performance of CFRP Multilayered Polyester Composites Under Dry/wet Contact Conditions

Science.gov (United States)

Danaelan, D.; Yousif, B. F.

The tribo-performance of a new engineering composite material based on coconut fibers was investigated. In this work, coconut fibers reinforced polyester (CFRP) composites were developed. The tribo-experiments were conducted by using pin-on-disc machine under dry and wet sliding contact condition against smooth stainless steel counterface. Worn surfaces were observed using optical microscope. Friction coefficient and specific wear rate were presented as a function of sliding distance (0-0.6 km) at different sliding velocities (0.1-0.28 m/s). The effect of applied load and sliding velocity was evaluated. The results showed that all test parameters have significant influence on friction and wear characteristics of the composites. Moreover, friction coefficient increased as the normal load and speed increased, the values were about 0.7-0.9 under dry contact condition. Meanwhile, under wet contact condition, there was a great reduction in the friction coefficient, i.e. the values were about 0.1-0.2. Furthermore, the specific wear rates were found to be around 2-4 (10-3) mm3/Nm under dry contact condition and highly reduced under wet condition. In other words, the presence of water as cleaner and polisher assisted to enhance the adhesive wear performance of CFRP by about 10%. The images from optical microscope showed evidence of adhesive wear mode with transition to abrasive wear mode at higher sliding velocities due to third body abrasion. On the other hand, optical images for wet condition showed less adhesive wear and smooth surfaces.

Interacting epidemics and coinfection on contact networks.

Directory of Open Access Journals (Sweden)

M E J Newman

Full Text Available The spread of certain diseases can be promoted, in some cases substantially, by prior infection with another disease. One example is that of HIV, whose immunosuppressant effects significantly increase the chances of infection with other pathogens. Such coinfection processes, when combined with nontrivial structure in the contact networks over which diseases spread, can lead to complex patterns of epidemiological behavior. Here we consider a mathematical model of two diseases spreading through a single population, where infection with one disease is dependent on prior infection with the other. We solve exactly for the sizes of the outbreaks of both diseases in the limit of large population size, along with the complete phase diagram of the system. Among other things, we use our model to demonstrate how diseases can be controlled not only by reducing the rate of their spread, but also by reducing the spread of other infections upon which they depend.

[Epidemiologic surveillance of contact allergens. The "monitoring series" of IVDK (Information Network ofDermatologic Clinics for Detection and Scientific Evaluation of Contact Allergy].

Science.gov (United States)

Aberer, W; Komericki, P; Uter, W; Hausen, B M; Lessmann, H; Kränke, B; Geier, J; Schnuch, A

2003-08-01

The selection of the most important contact allergens is subject to a continuous change. Several factors may influence the sensitization rates and thus the decision, which substances to include in the standard series of the most frequent allergens. The Information Network of Departments of Dermatology adds substances of interest for a certain time period to the standard series in order to evaluate parameters such as sensitization rate, grade of reaction, and clinical relevance of positive reactions. In 6 testing periods starting in 1996, 13 test substances were evaluated. Due to the results, propolis, compositae mix, and bufexamac were included in the standard series in 1999, while lyral was added in 2002. Sorbitansesquioleat, dispers blue mix, and iodopropynyl butylcarbamate are under further discussion. Substances such as glutaraldehyde and p-aminoazobenzole should be tested in certain risk groups only, whereas the steroids budesonide and tixocortol should be tested when clinically suspected.

Determination of work function of graphene under a metal electrode and its role in contact resistance.

Science.gov (United States)

Song, Seung Min; Park, Jong Kyung; Sul, One Jae; Cho, Byung Jin

2012-08-08

Although the work function of graphene under a given metal electrode is critical information for the realization of high-performance graphene-based electronic devices, relatively little relevant research has been carried out to date. In this work, the work function values of graphene under various metals are accurately measured for the first time through a detailed analysis of the capacitance-voltage (C-V) characteristics of a metal-graphene-oxide-semiconductor (MGOS) capacitor structure. In contrast to the high work function of exposed graphene of 4.89-5.16 eV, the work function of graphene under a metal electrode varies depending on the metal species. With a Cr/Au or Ni contact, the work function of graphene is pinned to that of the contacted metal, whereas with a Pd or Au contact the work function assumes a value of ∼4.62 eV regardless of the work function of the contact metal. A study of the gate voltage dependence on the contact resistance shows that the latter case provides lower contact resistance.

Failure mechanism of coated biomaterials under high impact-sliding contact stresses

Science.gov (United States)

Chen, Ying

This study uses a newly developed testing method--- inclined cyclic impact-sliding test to investigate the failure behaviors of different types of biomaterials, (SS316L, Ti6Al4V and CoCr) coated by different coatings (TiN, DLC and PEO), under extremely high dynamic contact stress conditions. This test method can simulate the combined impact and sliding/rolling loading conditions, which is very practical in many aspects of commercial usages. During the tests, fatigue cracking, chipping, peeling and material transferring were observed in damaged area. This research is mainly focused on the failure behaviors of load-bearing materials which cyclic impacting and sliding are always involved. This purpose was accomplished in the three stages: First, impact-sliding test was carried out on TiN coated unhardened M2. It was found that soft substrate can cause early failure of coating due to the considerable plastic deformation in the substrate. In this case, stronger substrate is required to support coating better when tested under high contact stresses. Second, PEO coated Ti-6Al-4V was tested under pure sliding and impact-sliding wear conditions. PEO coating was found not strong enough to afford the high contact pressure under cyclic impact-sliding wear test due to its porous surface structure. However, the wear performance of PEO coating was enhanced due to the sub-stoichiometric oxide. To sum up, for load-bearing biomedical implants involved in high impacting movement, PEO coating may not be a promising surface protection. Third, the dense, smooth PVD/CVD bio-inert coatings were reconsidered. DLC and TiN coatings, combined by different substrates together with different interface materials were tested under the cyclic impact-sliding test using a set of proper loading. The results show that to choose a proper combination of coating, interface and substrate based on their mechanical properties is of great importance under the test condition. Hard substrates provide support

Comparative Study of Elastic Network Model and Protein Contact Network for Protein Complexes: The Hemoglobin Case

Directory of Open Access Journals (Sweden)

Guang Hu

2017-01-01

Full Text Available The overall topology and interfacial interactions play key roles in understanding structural and functional principles of protein complexes. Elastic Network Model (ENM and Protein Contact Network (PCN are two widely used methods for high throughput investigation of structures and interactions within protein complexes. In this work, the comparative analysis of ENM and PCN relative to hemoglobin (Hb was taken as case study. We examine four types of structural and dynamical paradigms, namely, conformational change between different states of Hbs, modular analysis, allosteric mechanisms studies, and interface characterization of an Hb. The comparative study shows that ENM has an advantage in studying dynamical properties and protein-protein interfaces, while PCN is better for describing protein structures quantitatively both from local and from global levels. We suggest that the integration of ENM and PCN would give a potential but powerful tool in structural systems biology.

Synchronization analysis of coloured delayed networks under ...

Indian Academy of Sciences (India)

This paper investigates synchronization of coloured delayed networks under decentralized pinning intermittent control. To begin with, the time delays are taken into account in the coloured networks. In addition, we propose a decentralized pinning intermittent control for coloured delayed networks, which is different from that ...

Diagnosis of Constant Faults in Read-Once Contact Networks over Finite Bases using Decision Trees

KAUST Repository

Busbait, Monther I.

2014-01-01

We study the depth of decision trees for diagnosis of constant faults in read-once contact networks over finite bases. This includes diagnosis of 0-1 faults, 0 faults and 1 faults. For any finite basis, we prove a linear upper bound on the minimum

Device physics underlying silicon heterojunction and passivating-contact solar cells: A topical review

KAUST Repository

Chavali, Raghu V. K.

2018-01-15

The device physics of commercially dominant diffused-junction silicon solar cells is well understood, allowing sophisticated optimization of this class of devices. Recently, so-called passivating-contact solar cell technologies have become prominent, with Kaneka setting the world\\'s silicon solar cell efficiency record of 26.63% using silicon heterojunction contacts in an interdigitated configuration. Although passivating-contact solar cells are remarkably efficient, their underlying device physics is not yet completely understood, not in the least because they are constructed from diverse materials that may introduce electronic barriers in the current flow. To bridge this gap in understanding, we explore the device physics of passivating contact silicon heterojunction (SHJ) solar cells. Here, we identify the key properties of heterojunctions that affect cell efficiency, analyze the dependence of key heterojunction properties on carrier transport under light and dark conditions, provide a self-consistent multiprobe approach to extract heterojunction parameters using several characterization techniques (including dark J-V, light J-V, C-V, admittance spectroscopy, and Suns-Voc), propose design guidelines to address bottlenecks in energy production in SHJ cells, and develop a process-to-module modeling framework to establish the module\\'s performance limits. We expect that our proposed guidelines resulting from this multiscale and self-consistent framework will improve the performance of future SHJ cells as well as other passivating contact-based solar cells.

Contact Patterns in a High School: A Comparison between Data Collected Using Wearable Sensors, Contact Diaries and Friendship Surveys.

Directory of Open Access Journals (Sweden)

Rossana Mastrandrea

Full Text Available Given their importance in shaping social networks and determining how information or transmissible diseases propagate in a population, interactions between individuals are the subject of many data collection efforts. To this aim, different methods are commonly used, ranging from diaries and surveys to decentralised infrastructures based on wearable sensors. These methods have each advantages and limitations but are rarely compared in a given setting. Moreover, as surveys targeting friendship relations might suffer less from memory biases than contact diaries, it is interesting to explore how actual contact patterns occurring in day-to-day life compare with friendship relations and with online social links. Here we make progresses in these directions by leveraging data collected in a French high school and concerning (i face-to-face contacts measured by two concurrent methods, namely wearable sensors and contact diaries, (ii self-reported friendship surveys, and (iii online social links. We compare the resulting data sets and find that most short contacts are not reported in diaries while long contacts have a large reporting probability, and that the durations of contacts tend to be overestimated in the diaries. Moreover, measured contacts corresponding to reported friendship can have durations of any length but all long contacts do correspond to a reported friendship. On the contrary, online links that are not also reported in the friendship survey correspond to short face-to-face contacts, highlighting the difference of nature between reported friendships and online links. Diaries and surveys suffer moreover from a low sampling rate, as many students did not fill them, showing that the sensor-based platform had a higher acceptability. We also show that, despite the biases of diaries and surveys, the overall structure of the contact network, as quantified by the mixing patterns between classes, is correctly captured by both networks of self

Contact Patterns in a High School: A Comparison between Data Collected Using Wearable Sensors, Contact Diaries and Friendship Surveys.

Science.gov (United States)

Mastrandrea, Rossana; Fournet, Julie; Barrat, Alain

2015-01-01

Given their importance in shaping social networks and determining how information or transmissible diseases propagate in a population, interactions between individuals are the subject of many data collection efforts. To this aim, different methods are commonly used, ranging from diaries and surveys to decentralised infrastructures based on wearable sensors. These methods have each advantages and limitations but are rarely compared in a given setting. Moreover, as surveys targeting friendship relations might suffer less from memory biases than contact diaries, it is interesting to explore how actual contact patterns occurring in day-to-day life compare with friendship relations and with online social links. Here we make progresses in these directions by leveraging data collected in a French high school and concerning (i) face-to-face contacts measured by two concurrent methods, namely wearable sensors and contact diaries, (ii) self-reported friendship surveys, and (iii) online social links. We compare the resulting data sets and find that most short contacts are not reported in diaries while long contacts have a large reporting probability, and that the durations of contacts tend to be overestimated in the diaries. Moreover, measured contacts corresponding to reported friendship can have durations of any length but all long contacts do correspond to a reported friendship. On the contrary, online links that are not also reported in the friendship survey correspond to short face-to-face contacts, highlighting the difference of nature between reported friendships and online links. Diaries and surveys suffer moreover from a low sampling rate, as many students did not fill them, showing that the sensor-based platform had a higher acceptability. We also show that, despite the biases of diaries and surveys, the overall structure of the contact network, as quantified by the mixing patterns between classes, is correctly captured by both networks of self-reported contacts and

In vivo tibiofemoral cartilage-to-cartilage contact area of females with medial osteoarthritis under acute loading using MRI.

Science.gov (United States)

Shin, Choongsoo S; Souza, Richard B; Kumar, Deepak; Link, Thomas M; Wyman, Bradley T; Majumdar, Sharmila

2011-12-01

To investigate the effect of acute loading on in vivo tibiofemoral contact area changes in both compartments, and to determine whether in vivo tibiofemoral contact area differs between subjects with medial knee osteoarthritis (OA) and healthy controls. Ten subjects with medial knee OA (KL3) and 11 control subjects (KL0) were tested. Coronal three-dimensional spoiled gradient-recalled (3D-SPGR) and T(2) -weighted fast spin-echo FSE magnetic resonance imaging (MRI) of the knee were acquired under both unloaded and loaded conditions. Tibiofemoral cartilage contact areas were measured using image-based 3D models. Tibiofemoral contact areas in both compartments significantly increased under loading (P contact area in the medial compartment was significantly larger than in the lateral compartment (P contact area was significantly larger in KL3 subjects than KL0 subjects, both at unloaded and loaded conditions (P Contact areas measured from 3D-SPGR and T(2) -weighted FSE images were strongly correlated (r = 0.904). Females with medial OA increased tibiofemoral contact area in the medial compartment compared to healthy subjects under both unloaded and loaded conditions. The contact area data presented in this study may provide a quantitative reference for further cartilage contact biomechanics such as contact stress analysis and cartilage biomechanical function difference between osteoarthritic and healthy knees. Copyright © 2011 Wiley Periodicals, Inc.

Contact and contagion: Probability of transmission given contact varies with demographic state in bighorn sheep.

Science.gov (United States)

Manlove, Kezia R; Cassirer, E Frances; Plowright, Raina K; Cross, Paul C; Hudson, Peter J

2017-07-01

Understanding both contact and probability of transmission given contact are key to managing wildlife disease. However, wildlife disease research tends to focus on contact heterogeneity, in part because the probability of transmission given contact is notoriously difficult to measure. Here, we present a first step towards empirically investigating the probability of transmission given contact in free-ranging wildlife. We used measured contact networks to test whether bighorn sheep demographic states vary systematically in infectiousness or susceptibility to Mycoplasma ovipneumoniae, an agent responsible for bighorn sheep pneumonia. We built covariates using contact network metrics, demographic information and infection status, and used logistic regression to relate those covariates to lamb survival. The covariate set contained degree, a classic network metric describing node centrality, but also included covariates breaking the network metrics into subsets that differentiated between contacts with yearlings, ewes with lambs, and ewes without lambs, and animals with and without active infections. Yearlings, ewes with lambs, and ewes without lambs showed similar group membership patterns, but direct interactions involving touch occurred at a rate two orders of magnitude higher between lambs and reproductive ewes than between any classes of adults or yearlings, and one order of magnitude higher than direct interactions between multiple lambs. Although yearlings and non-reproductive bighorn ewes regularly carried M. ovipneumoniae, our models suggest that a contact with an infected reproductive ewe had approximately five times the odds of producing a lamb mortality event of an identical contact with an infected dry ewe or yearling. Consequently, management actions targeting infected animals might lead to unnecessary removal of young animals that carry pathogens but rarely transmit. This analysis demonstrates a simple logistic regression approach for testing a priori

Statistical inference to advance network models in epidemiology.

Science.gov (United States)

Welch, David; Bansal, Shweta; Hunter, David R

2011-03-01

Contact networks are playing an increasingly important role in the study of epidemiology. Most of the existing work in this area has focused on considering the effect of underlying network structure on epidemic dynamics by using tools from probability theory and computer simulation. This work has provided much insight on the role that heterogeneity in host contact patterns plays on infectious disease dynamics. Despite the important understanding afforded by the probability and simulation paradigm, this approach does not directly address important questions about the structure of contact networks such as what is the best network model for a particular mode of disease transmission, how parameter values of a given model should be estimated, or how precisely the data allow us to estimate these parameter values. We argue that these questions are best answered within a statistical framework and discuss the role of statistical inference in estimating contact networks from epidemiological data. Copyright © 2011 Elsevier B.V. All rights reserved.

Robustness analysis of interdependent networks under multiple-attacking strategies

Science.gov (United States)

Gao, Yan-Li; Chen, Shi-Ming; Nie, Sen; Ma, Fei; Guan, Jun-Jie

2018-04-01

The robustness of complex networks under attacks largely depends on the structure of a network and the nature of the attacks. Previous research on interdependent networks has focused on two types of initial attack: random attack and degree-based targeted attack. In this paper, a deliberate attack function is proposed, where six kinds of deliberate attacking strategies can be derived by adjusting the tunable parameters. Moreover, the robustness of four types of interdependent networks (BA-BA, ER-ER, BA-ER and ER-BA) with different coupling modes (random, positive and negative correlation) is evaluated under different attacking strategies. Interesting conclusions could be obtained. It can be found that the positive coupling mode can make the vulnerability of the interdependent network to be absolutely dependent on the most vulnerable sub-network under deliberate attacks, whereas random and negative coupling modes make the vulnerability of interdependent network to be mainly dependent on the being attacked sub-network. The robustness of interdependent network will be enhanced with the degree-degree correlation coefficient varying from positive to negative. Therefore, The negative coupling mode is relatively more optimal than others, which can substantially improve the robustness of the ER-ER network and ER-BA network. In terms of the attacking strategies on interdependent networks, the degree information of node is more valuable than the betweenness. In addition, we found a more efficient attacking strategy for each coupled interdependent network and proposed the corresponding protection strategy for suppressing cascading failure. Our results can be very useful for safety design and protection of interdependent networks.

Using Social Networking Sites for Communicable Disease Control: Innovative Contact Tracing or Breach of Confidentiality?

Science.gov (United States)

Mandeville, Kate L; Harris, Matthew; Thomas, H Lucy; Chow, Yimmy; Seng, Claude

2014-04-01

Social media applications such as Twitter, YouTube and Facebook have attained huge popularity, with more than three billion people and organizations predicted to have a social networking account by 2015. Social media offers a rapid avenue of communication with the public and has potential benefits for communicable disease control and surveillance. However, its application in everyday public health practice raises a number of important issues around confidentiality and autonomy. We report here a case from local level health protection where the friend of an individual with meningococcal septicaemia used a social networking site to notify potential contacts.

Analysis and Reduction of Complex Networks Under Uncertainty.

Energy Technology Data Exchange (ETDEWEB)

Ghanem, Roger G [University of Southern California

2014-07-31

This effort was a collaboration with Youssef Marzouk of MIT, Omar Knio of Duke University (at the time at Johns Hopkins University) and Habib Najm of Sandia National Laboratories. The objective of this effort was to develop the mathematical and algorithmic capacity to analyze complex networks under uncertainty. Of interest were chemical reaction networks and smart grid networks. The statements of work for USC focused on the development of stochastic reduced models for uncertain networks. The USC team was led by Professor Roger Ghanem and consisted of one graduate student and a postdoc. The contributions completed by the USC team consisted of 1) methodology and algorithms to address the eigenvalue problem, a problem of significance in the stability of networks under stochastic perturbations, 2) methodology and algorithms to characterize probability measures on graph structures with random flows. This is an important problem in characterizing random demand (encountered in smart grid) and random degradation (encountered in infrastructure systems), as well as modeling errors in Markov Chains (with ubiquitous relevance !). 3) methodology and algorithms for treating inequalities in uncertain systems. This is an important problem in the context of models for material failure and network flows under uncertainty where conditions of failure or flow are described in the form of inequalities between the state variables.

Contact Dynamics of EHL Contacts under Time Varying Conditions

NARCIS (Netherlands)

Venner, Cornelis H.; Popovici, G.; Wijnant, Ysbrand H.; Dalmaz, G.; Lubrecht, A.A.; Priest, M

2004-01-01

By means of numerical simulations of two situations with time varying operating conditions it is shown that the dynamic behaviour of Elasto-Hydrodynamically Lubricated contacts in terms of vibrations can be characterized as: Changes in the mutual approach lead to film thickness changes in the inlet

Some scale-free networks could be robust under selective node attacks

Science.gov (United States)

Zheng, Bojin; Huang, Dan; Li, Deyi; Chen, Guisheng; Lan, Wenfei

2011-04-01

It is a mainstream idea that scale-free network would be fragile under the selective attacks. Internet is a typical scale-free network in the real world, but it never collapses under the selective attacks of computer viruses and hackers. This phenomenon is different from the deduction of the idea above because this idea assumes the same cost to delete an arbitrary node. Hence this paper discusses the behaviors of the scale-free network under the selective node attack with different cost. Through the experiments on five complex networks, we show that the scale-free network is possibly robust under the selective node attacks; furthermore, the more compact the network is, and the larger the average degree is, then the more robust the network is; with the same average degrees, the more compact the network is, the more robust the network is. This result would enrich the theory of the invulnerability of the network, and can be used to build robust social, technological and biological networks, and also has the potential to find the target of drugs.

A sparse autoencoder-based deep neural network for protein solvent accessibility and contact number prediction.

Science.gov (United States)

Deng, Lei; Fan, Chao; Zeng, Zhiwen

2017-12-28

Direct prediction of the three-dimensional (3D) structures of proteins from one-dimensional (1D) sequences is a challenging problem. Significant structural characteristics such as solvent accessibility and contact number are essential for deriving restrains in modeling protein folding and protein 3D structure. Thus, accurately predicting these features is a critical step for 3D protein structure building. In this study, we present DeepSacon, a computational method that can effectively predict protein solvent accessibility and contact number by using a deep neural network, which is built based on stacked autoencoder and a dropout method. The results demonstrate that our proposed DeepSacon achieves a significant improvement in the prediction quality compared with the state-of-the-art methods. We obtain 0.70 three-state accuracy for solvent accessibility, 0.33 15-state accuracy and 0.74 Pearson Correlation Coefficient (PCC) for the contact number on the 5729 monomeric soluble globular protein dataset. We also evaluate the performance on the CASP11 benchmark dataset, DeepSacon achieves 0.68 three-state accuracy and 0.69 PCC for solvent accessibility and contact number, respectively. We have shown that DeepSacon can reliably predict solvent accessibility and contact number with stacked sparse autoencoder and a dropout approach.

Effect of different atmospheres on the electrical contact performance of electronic components under fretting wear

Science.gov (United States)

Liu, Xin-Long; Cai, Zhen-Bing; Cui, Ye; Liu, Shan-Bang; Xu, Xiao-Jun; Zhu, Min-Hao

2018-04-01

The effects of oxide etch on the surface morphology of metals for industrial application is a common cause of electrical contacts failure, and it has becomes a more severe problem with the miniaturization of modern electronic devices. This study investigated the effects of electrical contact resistance on the contactor under three different atmospheres (oxygen, air, and nitrogen) based on 99.9% copper/pogo pins contacts through fretting experiments. The results showed the minimum and stable electrical contact resistance value when shrouded in the nitrogen environment and with high friction coefficient. The rich oxygen environment promotes the formation of cuprous oxide, thereby the electrical contact resistance increases. Scanning electron microscope microscopy and electron probe microanalysis were used to analyze the morphology and distribution of elements of the wear area, respectively. The surface product between contacts was investigated by x-ray photoelectron spectroscopy analysis to explain the different electrical contact properties of the three tested samples during fretting.

A Mathematical and Numerically Integrable Modeling of 3D Object Grasping under Rolling Contacts between Smooth Surfaces

Directory of Open Access Journals (Sweden)

Suguru Arimoto

2011-01-01

Full Text Available A computable model of grasping and manipulation of a 3D rigid object with arbitrary smooth surfaces by multiple robot fingers with smooth fingertip surfaces is derived under rolling contact constraints between surfaces. Geometrical conditions of pure rolling contacts are described through the moving-frame coordinates at each rolling contact point under the postulates: (1 two surfaces share a common single contact point without any mutual penetration and a common tangent plane at the contact point and (2 each path length of running of the contact point on the robot fingertip surface and the object surface is equal. It is shown that a set of Euler-Lagrange equations of motion of the fingers-object system can be derived by introducing Lagrange multipliers corresponding to geometric conditions of contacts. A set of 1st-order differential equations governing rotational motions of each fingertip and the object and updating arc-length parameters should be accompanied with the Euler-Lagrange equations. Further more, nonholonomic constraints arising from twisting between the two normal axes to each tangent plane are rewritten into a set of Frenet-Serre equations with a geometrically given normal curvature and a motion-induced geodesic curvature.

Evolution of real contact area under shear and the value of static friction of soft materials.

Science.gov (United States)

Sahli, R; Pallares, G; Ducottet, C; Ben Ali, I E; Al Akhrass, S; Guibert, M; Scheibert, J

2018-01-16

The frictional properties of a rough contact interface are controlled by its area of real contact, the dynamical variations of which underlie our modern understanding of the ubiquitous rate-and-state friction law. In particular, the real contact area is proportional to the normal load, slowly increases at rest through aging, and drops at slip inception. Here, through direct measurements on various contacts involving elastomers or human fingertips, we show that the real contact area also decreases under shear, with reductions as large as 30[Formula: see text], starting well before macroscopic sliding. All data are captured by a single reduction law enabling excellent predictions of the static friction force. In elastomers, the area-reduction rate of individual contacts obeys a scaling law valid from micrometer-sized junctions in rough contacts to millimeter-sized smooth sphere/plane contacts. For the class of soft materials used here, our results should motivate first-order improvements of current contact mechanics models and prompt reinterpretation of the rate-and-state parameters.

Complex networks under dynamic repair model

Science.gov (United States)

Chaoqi, Fu; Ying, Wang; Kun, Zhao; Yangjun, Gao

2018-01-01

Invulnerability is not the only factor of importance when considering complex networks' security. It is also critical to have an effective and reasonable repair strategy. Existing research on network repair is confined to the static model. The dynamic model makes better use of the redundant capacity of repaired nodes and repairs the damaged network more efficiently than the static model; however, the dynamic repair model is complex and polytropic. In this paper, we construct a dynamic repair model and systematically describe the energy-transfer relationships between nodes in the repair process of the failure network. Nodes are divided into three types, corresponding to three structures. We find that the strong coupling structure is responsible for secondary failure of the repaired nodes and propose an algorithm that can select the most suitable targets (nodes or links) to repair the failure network with minimal cost. Two types of repair strategies are identified, with different effects under the two energy-transfer rules. The research results enable a more flexible approach to network repair.

New patterns in human biogeography revealed by networks of contacts between linguistic groups.

Science.gov (United States)

Capitán, José A; Bock Axelsen, Jacob; Manrubia, Susanna

2015-03-07

Human languages differ broadly in abundance and are distributed highly unevenly on the Earth. In many qualitative and quantitative aspects, they strongly resemble biodiversity distributions. An intriguing and previously unexplored issue is the architecture of the neighbouring relationships between human linguistic groups. Here we construct and characterize these networks of contacts and show that they represent a new kind of spatial network with uncommon structural properties. Remarkably, language networks share a meaningful property with food webs: both are quasi-interval graphs. In food webs, intervality is linked to the existence of a niche space of low dimensionality; in language networks, we show that the unique relevant variable is the area occupied by the speakers of a language. By means of a range model analogous to niche models in ecology, we show that a geometric restriction of perimeter covering by neighbouring linguistic domains explains the structural patterns observed. Our findings may be of interest in the development of models for language dynamics or regarding the propagation of cultural innovations. In relation to species distribution, they pose the question of whether the spatial features of species ranges share architecture, and eventually generating mechanism, with the distribution of human linguistic groups. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Double Contact During Drop Impact on a Solid Under Reduced Air Pressure

KAUST Repository

Li, Erqiang

2017-11-20

Drops impacting on solid surfaces entrap small bubbles under their centers, owing to the lubrication pressure which builds up in the thin intervening air layer. We use ultrahigh-speed interference imaging, at 5 Mfps, to investigate how this air layer changes when the ambient air pressure is reduced below atmospheric. Both the radius and the thickness of the air disc become smaller with reduced air pressure. Furthermore, we find the radial extent of the air disc bifurcates, when the compressibility parameter exceeds similar to 25. This bifurcation is also imprinted onto some of the impacts, as a double contact. In addition to the central air disc inside the first ring contact, this is immediately followed by a second ring contact, which entraps an outer toroidal strip of air, which contracts into a ring of bubbles. We find this occurs in a regime where Navier slip, due to rarefied gas effects, enhances the rate gas can escape from the path of the droplet.

Water Contact Angle Dependence with Hydroxyl Functional Groups on Silica Surfaces under CO2 Sequestration Conditions.

Science.gov (United States)

Chen, Cong; Zhang, Ning; Li, Weizhong; Song, Yongchen

2015-12-15

Functional groups on silica surfaces under CO2 sequestration conditions are complex due to reactions among supercritical CO2, brine and silica. Molecular dynamics simulations have been performed to investigate the effects of hydroxyl functional groups on wettability. It has been found that wettability shows a strong dependence on functional groups on silica surfaces: silanol number density, space distribution, and deprotonation/protonation degree. For neutral silica surfaces with crystalline structure (Q(3), Q(3)/Q(4), Q(4)), as silanol number density decreases, contact angle increases from 33.5° to 146.7° at 10.5 MPa and 318 K. When Q(3) surface changes to an amorphous structure, water contact angle increases 20°. Water contact angle decreases about 12° when 9% of silanol groups on Q(3) surface are deprotonated. When the deprotonation degree increases to 50%, water contact angle decreases to 0. The dependence of wettability on silica surface functional groups was used to analyze contact angle measurement ambiguity in literature. The composition of silica surfaces is complicated under CO2 sequestration conditions, the results found in this study may help to better understand wettability of CO2/brine/silica system.

Reliability of lifeline networks under seismic hazard

International Nuclear Information System (INIS)

Selcuk, A. Sevtap; Yuecemen, M. Semih

1999-01-01

Lifelines, such as pipelines, transportation, communication and power transmission systems, are networks which extend spatially over large geographical regions. The quantification of the reliability (survival probability) of a lifeline under seismic threat requires attention, as the proper functioning of these systems during or after a destructive earthquake is vital. In this study, a lifeline is idealized as an equivalent network with the capacity of its elements being random and spatially correlated and a comprehensive probabilistic model for the assessment of the reliability of lifelines under earthquake loads is developed. The seismic hazard that the network is exposed to is described by a probability distribution derived by using the past earthquake occurrence data. The seismic hazard analysis is based on the 'classical' seismic hazard analysis model with some modifications. An efficient algorithm developed by Yoo and Deo (Yoo YB, Deo N. A comparison of algorithms for terminal pair reliability. IEEE Transactions on Reliability 1988; 37: 210-215) is utilized for the evaluation of the network reliability. This algorithm eliminates the CPU time and memory capacity problems for large networks. A comprehensive computer program, called LIFEPACK is coded in Fortran language in order to carry out the numerical computations. Two detailed case studies are presented to show the implementation of the proposed model

Laser-fired contact formation on metallized and passivated silicon wafers under short pulse durations

Science.gov (United States)

Raghavan, Ashwin S.

The objective of this work is to develop a comprehensive understanding of the physical processes governing laser-fired contact (LFC) formation under microsecond pulse durations. Primary emphasis is placed on understanding how processing parameters influence contact morphology, passivation layer quality, alloying of Al and Si, and contact resistance. In addition, the research seeks to develop a quantitative method to accurately predict the contact geometry, thermal cycles, heat and mass transfer phenomena, and the influence of contact pitch distance on substrate temperatures in order to improve the physical understanding of the underlying processes. Finally, the work seeks to predict how geometry for LFCs produced with microsecond pulses will influence fabrication and performance factors, such as the rear side contacting scheme, rear surface series resistance and effective rear surface recombination rates. The characterization of LFC cross-sections reveals that the use of microsecond pulse durations results in the formation of three-dimensional hemispherical or half-ellipsoidal contact geometries. The LFC is heavily alloyed with Al and Si and is composed of a two-phase Al-Si microstructure that grows from the Si wafer during resolidification. As a result of forming a large three-dimensional contact geometry, the total contact resistance is governed by the interfacial contact area between the LFC and the wafer rather than the planar contact area at the original Al-Si interface within an opening in the passivation layer. By forming three-dimensional LFCs, the total contact resistance is significantly reduced in comparison to that predicted for planar contacts. In addition, despite the high energy densities associated with microsecond pulse durations, the passivation layer is well preserved outside of the immediate contact region. Therefore, the use of microsecond pulse durations can be used to improve device performance by leading to lower total contact resistances

Characterizing hydrophobicity of amino acid side chains in a protein environment via measuring contact angle of a water nanodroplet on planar peptide network.

Science.gov (United States)

Zhu, Chongqin; Gao, Yurui; Li, Hui; Meng, Sheng; Li, Lei; Francisco, Joseph S; Zeng, Xiao Cheng

2016-11-15

Hydrophobicity of macroscopic planar surface is conventionally characterized by the contact angle of water droplets. However, this engineering measurement cannot be directly extended to surfaces of proteins, due to the nanometer scale of amino acids and inherent nonplanar structures. To measure the hydrophobicity of side chains of proteins quantitatively, numerous parameters were developed to characterize behavior of hydrophobic solvation. However, consistency among these parameters is not always apparent. Herein, we demonstrate an alternative way of characterizing hydrophobicity of amino acid side chains in a protein environment by constructing a monolayer of amino acids (i.e., artificial planar peptide network) according to the primary and the β-sheet secondary structures of protein so that the conventional engineering measurement of the contact angle of a water droplet can be brought to bear. Using molecular dynamics simulations, contact angles θ of a water nanodroplet on the planar peptide network, together with excess chemical potentials of purely repulsive methane-sized Weeks-Chandler-Andersen solute, are computed. All of the 20 types of amino acids and the corresponding planar peptide networks are studied. Expectedly, all of the planar peptide networks with nonpolar amino acids are hydrophobic due to θ [Formula: see text] 90°, whereas all of the planar peptide networks of the polar and charged amino acids are hydrophilic due to θ [Formula: see text] 90°. Planar peptide networks of the charged amino acids exhibit complete-wetting behavior due to θ [Formula: see text] 0°. This computational approach for characterization of hydrophobicity can be extended to artificial planar networks of other soft matter.

Social network community structure and the contact-mediated sharing of commensal E. coli among captive rhesus macaques (Macaca mulatta).

Science.gov (United States)

Balasubramaniam, Krishna; Beisner, Brianne; Guan, Jiahui; Vandeleest, Jessica; Fushing, Hsieh; Atwill, Edward; McCowan, Brenda

2018-01-01

In group-living animals, heterogeneity in individuals' social connections may mediate the sharing of microbial infectious agents. In this regard, the genetic relatedness of individuals' commensal gut bacterium Escherichia coli may be ideal to assess the potential for pathogen transmission through animal social networks. Here we use microbial phylogenetics and population genetics approaches, as well as host social network reconstruction, to assess evidence for the contact-mediated sharing of E. coli among three groups of captively housed rhesus macaques ( Macaca mulatta ), at multiple organizational scales. For each group, behavioral data on grooming, huddling, and aggressive interactions collected for a six-week period were used to reconstruct social network communities via the Data Cloud Geometry (DCG) clustering algorithm. Further, an E. coli isolate was biochemically confirmed and genotypically fingerprinted from fecal swabs collected from each macaque. Population genetics approaches revealed that Group Membership, in comparison to intrinsic attributes like age, sex, and/or matriline membership of individuals, accounted for the highest proportion of variance in E. coli genotypic similarity. Social network approaches revealed that such sharing was evident at the community-level rather than the dyadic level. Specifically, although we found no links between dyadic E. coli similarity and social contact frequencies, similarity was significantly greater among macaques within the same social network communities compared to those across different communities. Moreover, tests for one of our study-groups confirmed that E. coli isolated from macaque rectal swabs were more genotypically similar to each other than they were to isolates from environmentally deposited feces. In summary, our results suggest that among frequently interacting, spatially constrained macaques with complex social relationships, microbial sharing via fecal-oral, social contact-mediated routes may

Patch test results of the European baseline series among patients with occupational contact dermatitis across Europe - analyses of the European Surveillance System on Contact Allergy network, 2002-2010.

Science.gov (United States)

Pesonen, Maria; Jolanki, Riitta; Larese Filon, Francesca; Wilkinson, Mark; Kręcisz, Beata; Kieć-Świerczyńska, Marta; Bauer, Andrea; Mahler, Vera; John, Swen M; Schnuch, Axel; Uter, Wolfgang

2015-03-01

Occupational contact dermatitis is one of the most common occupational diseases in Europe. In order to develop effective preventive measures, detailed and up-to-date data on the incidence, main causes and professions at risk of occupational contact dermatitis are needed. To describe the pattern of patch test reactivity to allergens in the European baseline series of patients with occupational contact dermatitis in different occupations. We analysed data collected by the European Surveillance System on Contact Allergy (ESSCA) network from 2002 to 2010, from 11 European countries. Allergens in the European baseline series associated with an at least doubled risk of occupational contact dermatitis include: thiuram rubber chemical accelerators, epoxy resin, and the antimicrobials methylchloroisothiazolinone/methylisothiazolinone, methyldibromo glutaronitrile, and formaldehyde. The highest risk of occupational contact dermatitis was found in occupations classified as 'other personal services workers', which includes hairdressers, nursing and other healthcare professionals, precision workers in metal and related materials, and blacksmiths, tool-makers and related trades workers. In the planning and implementation of measures aimed at preventing occupational contact dermatitis, the focus should be on the identified high-risk occupational groups and the most common occupational allergies. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Line and lattice networks under deterministic interference models

NARCIS (Netherlands)

Goseling, Jasper; Gastpar, Michael; Weber, Jos H.

Capacity bounds are compared for four different deterministic models of wireless networks, representing four different ways of handling broadcast and superposition in the physical layer. In particular, the transport capacity under a multiple unicast traffic pattern is studied for a 1-D network of

A non-contact shape measuring system using an artificial neural network

International Nuclear Information System (INIS)

Jeon, Woo Tae; Lee, Myung Chan; Koh, Duck Joon; Cho, Hyung Suck

1996-01-01

We developed a non-contact shape measuring device using computer image processing technology. We present a method of calibrating a CCD video camera and a laser range finder which is the most important step toward making an accurate shape measuring system. An artificial neural network is used for the calibration. Our measurement system is composed of a semiconductor laser, a CCD video camera, a personal computer, and a linear motion table. We think that the developed system could be used for measuring the change in shape of the spent nuclear fuel rod before and after irradiation which is one of the most important tasks for developing a better nuclear fuel. A radiation shield is suggested for the possible utilization of the range finder in radioactive environment

Flows in networks under fuzzy conditions

CERN Document Server

Bozhenyuk, Alexander Vitalievich; Kacprzyk, Janusz; Rozenberg, Igor Naymovich

2017-01-01

This book offers a comprehensive introduction to fuzzy methods for solving flow tasks in both transportation and networks. It analyzes the problems of minimum cost and maximum flow finding with fuzzy nonzero lower flow bounds, and describes solutions to minimum cost flow finding in a network with fuzzy arc capacities and transmission costs. After a concise introduction to flow theory and tasks, the book analyzes two important problems. The first is related to determining the maximum volume for cargo transportation in the presence of uncertain network parameters, such as environmental changes, measurement errors and repair work on the roads. These parameters are represented here as fuzzy triangular, trapezoidal numbers and intervals. The second problem concerns static and dynamic flow finding in networks under fuzzy conditions, and an effective method that takes into account the network’s transit parameters is presented here. All in all, the book provides readers with a practical reference guide to state-of-...

Electrical equivalent thermal network for direct contact membrane distillation modeling and analysis

KAUST Repository

Karam, Ayman M.

2016-09-19

Membrane distillation (MD) is an emerging water desalination technology that offers several advantages compared to conventional desalination methods. Although progress has been made to model the physics of the process, there are two common limitations of existing models. Firstly, many of the models are based on the steady-state analysis of the process and secondly, some of the models are based on partial differential equations, which when discretized introduce many states which are not accessible in practice. This paper presents the derivation of a novel dynamic model, based on the analogy between electrical and thermal systems, for direct contact membrane distillation (DCMD). An analogous electrical thermal network is constructed and its elements are parameterized such that the response of the network models the DCMD process. The proposed model captures the spatial and temporal responses of the temperature distribution along the flow direction and is able to accurately predict the distilled water flux output. To demonstrate the adequacy of the proposed model, validation with time varying and steady-state experimental data is presented. (C) 2016 Elsevier Ltd. All rights reserved.

Connection Management and Recovery Strategies under Epidemic Network Failures in Optical Transport Networks

DEFF Research Database (Denmark)

Fagertun, Anna Manolova; Ruepp, Sarah Renée

2014-01-01

The current trend in deploying automatic control plane solutions for increased flexibility in the optical transport layer leads to numerous advantages for both the operators and the customers, but also pose challenges related to the stability of the network and its ability to operate in a robust...... manner under attacks. This work proposes four policies for failure handling in a connection-oriented optical transport network, under Generalized MultiProtocol Label Switching control plane, and evaluates their performance under multiple correlated large-scale failures. We employ the Susceptible...... of their transport infrastructures. Applying proactive methods for avoiding areas where epidemic failures spread results in 50% less connections requiring recovery, which translates in improved quality of service to customers....

The association of drinking water treatment and distribution network disturbances with Health Call Centre contacts for gastrointestinal illness symptoms.

Science.gov (United States)

Malm, Annika; Axelsson, Gösta; Barregard, Lars; Ljungqvist, Jakob; Forsberg, Bertil; Bergstedt, Olof; Pettersson, Thomas J R

2013-09-01

There are relatively few studies on the association between disturbances in drinking water services and symptoms of gastrointestinal (GI) illness. Health Call Centres data concerning GI illness may be a useful source of information. This study investigates if there is an increased frequency of contacts with the Health Call Centre (HCC) concerning gastrointestinal symptoms at times when there is a risk of impaired water quality due to disturbances at water works or the distribution network. The study was conducted in Gothenburg, a Swedish city with 0.5 million inhabitants with a surface water source of drinking water and two water works. All HCC contacts due to GI symptoms (diarrhoea, vomiting or abdominal pain) were recorded for a three-year period, including also sex, age, and geocoded location of residence. The number of contacts with the HCC in the affected geographical areas were recorded during eight periods of disturbances in the water works (e.g. short stops of chlorine dosing), six periods of large disturbances in the distribution network (e.g. pumping station failure or pipe breaks with major consequences), and 818 pipe break and leak repairs over a three-year period. For each period of disturbance the observed number of calls was compared with the number of calls during a control period without disturbances in the same geographical area. In total about 55, 000 calls to the HCC due to GI symptoms were recorded over the three-year period, 35 per 1000 inhabitants and year, but much higher (>200) for children water works or in the distribution network. Our results indicate that GI symptoms due to disturbances in water works or the distribution network are rare. The number of serious failures was, however limited, and further studies are needed to be able to assess the risk of GI illness in such cases. The technique of using geocoded HCC data together with geocoded records of disturbances in the drinking water network was feasible. Copyright © 2013 Elsevier

Stability of selected volatile contact allergens in different patch test chambers under different storage conditions.

Science.gov (United States)

Mose, Kristian F; Andersen, Klaus E; Christensen, Lars Porskjaer

2012-04-01

Patch test preparations of volatile substances may evaporate during storage, thereby giving rise to reduced patch test concentrations. To investigate the stability of selected acrylates/methacrylates and fragrance allergens in three different test chambers under different storage conditions. Petrolatum samples of methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (2-HEMA), 2-hydroxypropyl acrylate (2-HPA), cinnamal and eugenol in patch test concentrations were stored in three different test chambers (IQ chamber™, IQ Ultimate™, and Van der Bend® transport container) at room temperature and in a refrigerator. The samples were analysed in triplicate with high-performance liquid chromatography. The decrease in concentration was substantial for all five allergens under both storage conditions in IQ chamber™ and IQ Ultimate™, with the exception of 2-HEMA during storage in the refrigerator. For these two chamber systems, the contact allergen concentration dropped below the stability limit in the following order: MMA, cinnamal, 2-HPA, eugenol, and 2-HEMA. In the Van der Bend® transport container, the contact allergens exhibited acceptable stability under both storage conditions, whereas MMA and 2-HPA required cool storage for maintenance of the limit. The Van der Bend® transport container was the best device for storage of samples of volatile contact allergens. © 2012 John Wiley & Sons A/S.

Competing spreading processes and immunization in multiplex networks

International Nuclear Information System (INIS)

Gao, Bo; Deng, Zhenghong; Zhao, Dawei

2016-01-01

Epidemic spreading on physical contact network will naturally introduce the human awareness information diffusion on virtual contact network, and the awareness diffusion will in turn depress the epidemic spreading, thus forming the competing spreading processes of epidemic and awareness in a multiplex networks. In this paper, we study the competing dynamics of epidemic and awareness, both of which follow the SIR process, in a two-layer networks based on microscopic Markov chain approach and numerical simulations. We find that strong capacities of awareness diffusion and self-protection of individuals could lead to a much higher epidemic threshold and a smaller outbreak size. However, the self-awareness of individuals has no obvious effect on the epidemic threshold and outbreak size. In addition, the immunization of the physical contact network under the interplay between of epidemic and awareness spreading is also investigated. The targeted immunization is found performs much better than random immunization, and the awareness diffusion could reduce the immunization threshold for both type of random and targeted immunization significantly.

Asymptotic stability of a genetic network under impulsive control

International Nuclear Information System (INIS)

Li Fangfei; Sun Jitao

2010-01-01

The study of the stability of genetic network is an important motif for the understanding of the living organism at both molecular and cellular levels. In this Letter, we provide a theoretical method for analyzing the asymptotic stability of a genetic network under impulsive control. And the sufficient conditions of its asymptotic stability under impulsive control are obtained. Finally, an example is given to illustrate the effectiveness of the obtained method.

Increased resistance of contact lens related bacterial biofilms to antimicrobial activity of soft contact lens care solutions

Science.gov (United States)

Szczotka-Flynn, Loretta B.; Imamura, Yoshifumi; Chandra, Jyotsna; Yu, Changping; Mukherjee, Pranab K.; Pearlman, Eric; Ghannoum, Mahmoud A.

2014-01-01

PURPOSE To determine if clinical and reference strains of Pseudomonas aeruginosa, Serratia marcescens, and Staphylococcus aureus form biofilms on silicone hydrogel contact lenses, and ascertain antimicrobial activities of contact lens care solutions. METHODS Clinical and American Type Culture Collection (ATCC) reference strains of Pseudomonas aeruginosa, Serratia marcescens, and Staphylococcus aureus were incubated with lotrafilcon A lenses under conditions that facilitate biofilm formation. Biofilms were quantified by quantitative culturing (colony forming units, CFUs), and gross morphology and architecture were evaluated using scanning electron microscopy (SEM) and confocal microscopy. Susceptibilities of the planktonic and biofilm growth phases of the bacteria to five common multipurpose contact lens care solutions and one hydrogen peroxide care solution were assessed. RESULTS P. aeruginosa, S. marcescens, and S. aureus reference and clinical strains formed biofilms on lotrafilcon A silicone hydrogel contact lenses, as dense networks of cells arranged in multiple layers with visible extracellular matrix. The biofilms were resistant to commonly used biguanide preserved multipurpose care solutions. P. aeruginosa and S. aureus biofilms were susceptible to a hydrogen peroxide and a polyquaternium preserved care solution, whereas S. marcescens biofilm was resistant to a polyquaternium preserved care solution but susceptible to hydrogen peroxide disinfection. In contrast, the planktonic forms were always susceptible. CONCLUSIONS P. aeruginosa, S. marcescens, and S. aureus form biofilms on lotrafilcon A contact lenses, which in contrast to planktonic cells, are resistant to the antimicrobial activity of several soft contact lens care products. PMID:19654521

Analyses of a steel containment vessel with an outer contact structure under severe internal overpressurization conditions

International Nuclear Information System (INIS)

Porter, V.L.

1994-01-01

Many Mark-I and Mark-II BWR plants are designed with a steel vessel as the primary containment. Typically, the steel containment vessel (SCV) is enclosed within a reinforced concrete shield building with only a small gap (74-90 mm) separating the two structures. This paper describes finite element analyses performed to evaluate the effects of contact and friction between a steel containment vessel and an outer contact structure when the containment vessel is subjected to large internal pressures. These computations were motivated by a joint program on containment integrity involving the Nuclear Power Engineering Corporation (NUPEC) of Japan, the US Nuclear Regulatory Commission (NRC), and Sandia National Laboratories for testing model containments. Under severe accident loading conditions, the steel containment vessel in a typical Mark-I or Mark-II plant may deform under internal pressurization such that it contacts the inner surface of a shield building wall. (Thermal expansion from increasing accident temperatures would also close the gap between the SCV and the shield building, but temperature effects are not considered in these analyses.) The amount and location of contact and the pressure at which it occurs all affect how the combined structure behaves. A preliminary finite element model has been developed to analyze a model of a typical steel containment vessel con-ling into contact with an outer structure. Both the steel containment vessel and the outer contact structure were modelled with axisymmetric shell finite elements. Of particular interest are the influence that the contact structure has on deformation and potential failure modes of the containment vessel. Furthermore, the coefficient of friction between the two structures was varied to study its effects on the behavior of the containment vessel and on the uplift loads transmitted to the contact structure. These analyses show that the material properties of an outer contact structure and the amount

Robust Optimization of Fourth Party Logistics Network Design under Disruptions

Directory of Open Access Journals (Sweden)

Jia Li

2015-01-01

Full Text Available The Fourth Party Logistics (4PL network faces disruptions of various sorts under the dynamic and complex environment. In order to explore the robustness of the network, the 4PL network design with consideration of random disruptions is studied. The purpose of the research is to construct a 4PL network that can provide satisfactory service to customers at a lower cost when disruptions strike. Based on the definition of β-robustness, a robust optimization model of 4PL network design under disruptions is established. Based on the NP-hard characteristic of the problem, the artificial fish swarm algorithm (AFSA and the genetic algorithm (GA are developed. The effectiveness of the algorithms is tested and compared by simulation examples. By comparing the optimal solutions of the 4PL network for different robustness level, it is indicated that the robust optimization model can evade the market risks effectively and save the cost in the maximum limit when it is applied to 4PL network design.

A social activity and physical contact-based routing algorithm in mobile opportunistic networks for emergency response to sudden disasters

Science.gov (United States)

Wang, Xiaoming; Lin, Yaguang; Zhang, Shanshan; Cai, Zhipeng

2017-05-01

Sudden disasters such as earthquake, flood and hurricane necessitate the employment of communication networks to carry out emergency response activities. Routing has a significant impact on the functionality, performance and flexibility of communication networks. In this article, the routing problem is studied considering the delivery ratio of messages, the overhead ratio of messages and the average delay of messages in mobile opportunistic networks (MONs) for enterprise-level emergency response communications in sudden disaster scenarios. Unlike the traditional routing methods for MONS, this article presents a new two-stage spreading and forwarding dynamic routing algorithm based on the proposed social activity degree and physical contact factor for mobile customers. A new modelling method for describing a dynamic evolving process of the topology structure of a MON is first proposed. Then a multi-copy spreading strategy based on the social activity degree of nodes and a single-copy forwarding strategy based on the physical contact factor between nodes are designed. Compared with the most relevant routing algorithms such as Epidemic, Prophet, Labelled-sim, Dlife-comm and Distribute-sim, the proposed routing algorithm can significantly increase the delivery ratio of messages, and decrease the overhead ratio and average delay of messages.

Spatial networks

Science.gov (United States)

Barthélemy, Marc

2011-02-01

Complex systems are very often organized under the form of networks where nodes and edges are embedded in space. Transportation and mobility networks, Internet, mobile phone networks, power grids, social and contact networks, and neural networks, are all examples where space is relevant and where topology alone does not contain all the information. Characterizing and understanding the structure and the evolution of spatial networks is thus crucial for many different fields, ranging from urbanism to epidemiology. An important consequence of space on networks is that there is a cost associated with the length of edges which in turn has dramatic effects on the topological structure of these networks. We will thoroughly explain the current state of our understanding of how the spatial constraints affect the structure and properties of these networks. We will review the most recent empirical observations and the most important models of spatial networks. We will also discuss various processes which take place on these spatial networks, such as phase transitions, random walks, synchronization, navigation, resilience, and disease spread.

Electrical contacts to nanorod networks at different length scales: From macroscale ensembles to single nanorod chains

KAUST Repository

Lavieville, Romain; Zhang, Yang; Di Fabrizio, Enzo M.; Krahne, Roman

2013-01-01

The nature of metal-semiconductor interfaces at the nanoscale is an important issue in micro- and nanoelectronic engineering. The study of charge transport through chains of CdSe semiconductor nanorods linked by Au particles represents an ideal model system for this matter, because the metal semiconductor interface is an intrinsic feature of the nanosystem. Here we show the controlled fabrication of all-inorganic hybrid metal-semiconductor networks with different size, in which the semiconductor nanorods are linked by Au domains at their tips. We demonstrate different approaches to selectively contact the networks and single nanorod chains with planar electrodes, and we investigate their charge transport at room temperature. © 2013 Elsevier B.V. All rights reserved.

Electrical contacts to nanorod networks at different length scales: From macroscale ensembles to single nanorod chains

KAUST Repository

Lavieville, Romain

2013-11-01

The nature of metal-semiconductor interfaces at the nanoscale is an important issue in micro- and nanoelectronic engineering. The study of charge transport through chains of CdSe semiconductor nanorods linked by Au particles represents an ideal model system for this matter, because the metal semiconductor interface is an intrinsic feature of the nanosystem. Here we show the controlled fabrication of all-inorganic hybrid metal-semiconductor networks with different size, in which the semiconductor nanorods are linked by Au domains at their tips. We demonstrate different approaches to selectively contact the networks and single nanorod chains with planar electrodes, and we investigate their charge transport at room temperature. © 2013 Elsevier B.V. All rights reserved.

Role of long- and short-range hydrophobic, hydrophilic and charged residues contact network in protein’s structural organization

Directory of Open Access Journals (Sweden)

Sengupta Dhriti

2012-06-01

Full Text Available Abstract Background The three-dimensional structure of a protein can be described as a graph where nodes represent residues and the strength of non-covalent interactions between them are edges. These protein contact networks can be separated into long and short-range interactions networks depending on the positions of amino acids in primary structure. Long-range interactions play a distinct role in determining the tertiary structure of a protein while short-range interactions could largely contribute to the secondary structure formations. In addition, physico chemical properties and the linear arrangement of amino acids of the primary structure of a protein determines its three dimensional structure. Here, we present an extensive analysis of protein contact subnetworks based on the London van der Waals interactions of amino acids at different length scales. We further subdivided those networks in hydrophobic, hydrophilic and charged residues networks and have tried to correlate their influence in the overall topology and organization of a protein. Results The largest connected component (LCC of long (LRN-, short (SRN- and all-range (ARN networks within proteins exhibit a transition behaviour when plotted against different interaction strengths of edges among amino acid nodes. While short-range networks having chain like structures exhibit highly cooperative transition; long- and all-range networks, which are more similar to each other, have non-chain like structures and show less cooperativity. Further, the hydrophobic residues subnetworks in long- and all-range networks have similar transition behaviours with all residues all-range networks, but the hydrophilic and charged residues networks don’t. While the nature of transitions of LCC’s sizes is same in SRNs for thermophiles and mesophiles, there exists a clear difference in LRNs. The presence of larger size of interconnected long-range interactions in thermophiles than mesophiles, even at

An innovative wheel–rail contact model for railway vehicles under degraded adhesion conditions

International Nuclear Information System (INIS)

Meli, E.; Ridolfi, A.

2015-01-01

The accurate modelling of the wheel–rail contact plays a fundamental role in the railway field since the contact forces heavily affect the vehicle dynamics, the wear of the contact surfaces and the vehicle safety. Concerning the wheel–rail contact, an important open problem is represented by the degraded adhesion. A realistic adhesion model is quite difficult to obtain because of the complex and highly non-linear behaviour of the adhesion coefficient and the presence of external unknown contaminants (the third body); this is especially true when degraded adhesion and large sliding between the wheel and rail contact surfaces occur.In this work the authors present an adhesion model particularly developed to describe degraded adhesion conditions. The new approach will have to be suitable to be employed within the wheel–rail contact models typical of the multibody applications. In other words, the contact model, comprising the new adhesion model, will have to guarantee a good accuracy and, at the same time, a high numerical efficiency to be implemented directly online inside the general multibody model of the vehicles (e.g. in Matlab-Simulink or Simpack environments) ( www.mathworks.com http://www.mathworks.com , 2012; www.simpack.com http://www.simpack.com , 2012).The model analysed in the paper is based on some of the main phenomena characterising the degraded adhesion, such as large sliding at the contact interface, high energy dissipation, the consequent cleaning effect on the contact surfaces and the final adhesion recovery due to the removal of external unknown contaminants.The adhesion model has been validated because of the experimental data provided by Trenitalia S.p.A. coming from on-track tests performed in Velim (Czech Republic). The tests have been carried out on a straight railway track under degraded adhesion conditions with the railway vehicle UIC-Z1 equipped with a fully-working Wheel Slide Protection (WSP) system.The validation highlighted the

An innovative wheel–rail contact model for railway vehicles under degraded adhesion conditions

Energy Technology Data Exchange (ETDEWEB)

Meli, E., E-mail: enrico.meli@unifi.it; Ridolfi, A., E-mail: a.ridolfi@unifi.it [University of Florence, Department of Industrial Engineering (Italy)

2015-03-15

The accurate modelling of the wheel–rail contact plays a fundamental role in the railway field since the contact forces heavily affect the vehicle dynamics, the wear of the contact surfaces and the vehicle safety. Concerning the wheel–rail contact, an important open problem is represented by the degraded adhesion. A realistic adhesion model is quite difficult to obtain because of the complex and highly non-linear behaviour of the adhesion coefficient and the presence of external unknown contaminants (the third body); this is especially true when degraded adhesion and large sliding between the wheel and rail contact surfaces occur.In this work the authors present an adhesion model particularly developed to describe degraded adhesion conditions. The new approach will have to be suitable to be employed within the wheel–rail contact models typical of the multibody applications. In other words, the contact model, comprising the new adhesion model, will have to guarantee a good accuracy and, at the same time, a high numerical efficiency to be implemented directly online inside the general multibody model of the vehicles (e.g. in Matlab-Simulink or Simpack environments) ( www.mathworks.com http://www.mathworks.com , 2012; www.simpack.com http://www.simpack.com , 2012).The model analysed in the paper is based on some of the main phenomena characterising the degraded adhesion, such as large sliding at the contact interface, high energy dissipation, the consequent cleaning effect on the contact surfaces and the final adhesion recovery due to the removal of external unknown contaminants.The adhesion model has been validated because of the experimental data provided by Trenitalia S.p.A. coming from on-track tests performed in Velim (Czech Republic). The tests have been carried out on a straight railway track under degraded adhesion conditions with the railway vehicle UIC-Z1 equipped with a fully-working Wheel Slide Protection (WSP) system.The validation highlighted the

Energy network dispatch optimization under emergency of local energy shortage

International Nuclear Information System (INIS)

Cai, Tianxing; Zhao, Chuanyu; Xu, Qiang

2012-01-01

The consequence of short-time energy shortage under extreme conditions, such as earthquake, tsunami, and hurricane, may cause local areas to suffer from delayed rescues, widespread power outages, tremendous economic losses, and even public safety threats. In such urgent events of local energy shortage, agile energy dispatching through an effective energy transportation network, targeting the minimum energy recovery time, should be a top priority. In this paper, a novel methodology is developed for energy network dispatch optimization under emergency of local energy shortage, which includes four stages of work. First, emergency-area-centered energy network needs to be characterized, where the capacity, quantity, and availability of various energy sources are determined. Second, the energy initial situation under emergency conditions needs to be identified. Then, the energy dispatch optimization is conducted based on a developed MILP (mixed-integer linear programming) model in the third stage. Finally, the sensitivity of the minimum dispatch time with respect to uncertainty parameters is characterized by partitioning the entire space of uncertainty parameters into multiple subspaces. The efficacy of the developed methodology is demonstrated via a case study with in-depth discussions. -- Highlights: ► Address the energy network dispatch problem under emergency of local energy shortage. ► Minimize the energy restoration time for the entire energy network under emergency events. ► Develop a new MILP model and a sensitivity analysis method with respect to uncertainties.

The role of network bridging organisations in compensation payments for agri-environmental services under the EU Common Agricultural Policy.

Science.gov (United States)

Dedeurwaerdere, Tom; Polard, Audrey; Melindi-Ghidi, Paolo

2015-11-01

Compensation payments to farmers for the provision of agri-environmental services are a well-established policy scheme under the EU Common Agricultural Policy. However, in spite of the success in most EU countries in the uptake of the programme by farmers, the impact of the scheme on the long term commitment of farmers to change their practices remains poorly documented. To explore this issue, this paper presents the results of structured field interviews and a quantitative survey in the Walloon Region of Belgium. The main finding of this study is that farmers who have periodic contacts with network bridging organisations that foster cooperation and social learning in the agri-environmental landscapes show a higher commitment to change. This effect is observed both for farmers with high and low concern for biodiversity depletion. Support for network bridging organisations is foreseen under the EU Leader programme and the EU regulation 1306/2013, which could open-up interesting opportunities for enhancing the effectiveness of the current payment scheme for agri-environmental services.

Evaluation of metal–nanowire electrical contacts by measuring contact end resistance

International Nuclear Information System (INIS)

Park, Hongsik; Beresford, Roderic; Xu, Jimmy; Ha, Ryong; Choi, Heon-Jin; Shin, Hyunjung

2012-01-01

It is known, but often unappreciated, that the performance of nanowire (NW)-based electrical devices can be significantly affected by electrical contacts between electrodes and NWs, sometimes to the extent that it is really the contacts that determine the performance. To correctly understand and design NW device operation, it is thus important to carefully measure the contact resistance and evaluate the contact parameters, specific contact resistance and transfer length. A four-terminal pattern or a transmission line model (TLM) pattern has been widely used to measure contact resistance of NW devices and the TLM has been typically used to extract contact parameters of NW devices. However, the conventional method assumes that the electrical properties of semiconducting NW regions covered by a metal are not changed after electrode formation. In this study, we report that the conventional methods for contact evaluation can give rise to considerable errors because of an altered property of the NW under the electrodes. We demonstrate that more correct contact resistance can be measured from the TLM pattern rather than the four-terminal pattern and correct contact parameters including the effects of changed NW properties under electrodes can be evaluated by using the contact end resistance measurement method. (paper)

Contact and symplectic topology

CERN Document Server

Colin, Vincent; Stipsicz, András

2014-01-01

Symplectic and contact geometry naturally emerged from the mathematical description of classical physics. The discovery of new rigidity phenomena and properties satisfied by these geometric structures launched a new research field worldwide. The intense activity of many European research groups in this field is reflected by the ESF Research Networking Programme "Contact And Symplectic Topology" (CAST). The lectures of the Summer School in Nantes (June 2011) and of the CAST Summer School in Budapest (July 2012) provide a nice panorama of many aspects of the present status of contact and symplectic topology. The notes of the minicourses offer a gentle introduction to topics which have developed in an amazing speed in the recent past. These topics include 3-dimensional and higher dimensional contact topology, Fukaya categories, asymptotically holomorphic methods in contact topology, bordered Floer homology, embedded contact homology, and flexibility results for Stein manifolds.

Contact Line Instability Caused by Air Rim Formation under Nonsplashing Droplets.

Science.gov (United States)

Pack, Min; Kaneelil, Paul; Kim, Hyoungsoo; Sun, Ying

2018-05-01

Drop impact is fundamental to various natural and industrial processes such as rain-induced soil erosion and spray-coating technologies. The recent discovery of the role of air entrainment between the droplet and the impacting surface has produced numerous works, uncovering the unique physics that correlates the air film dynamics with the drop impact outcomes. In this study, we focus on the post-failure air entrainment dynamics for We numbers well below the splash threshold under different ambient pressures and elucidate the interfacial instabilities formed by air entrainment at the wetting front of impacting droplets on perfectly smooth, viscous films of constant thickness. A high-speed total internal reflection microscopy technique accounting for the Fresnel reflection at the drop-air interface allows for in situ measurements of an entrained air rim at the wetting front. The presence of an air rim is found to be a prerequisite to the interfacial instability which is formed when the capillary pressure in the vicinity of the contact line can no longer balance the increasing gas pressure near the wetting front. A critical capillary number for the air rim formation is experimentally identified above which the wetting front becomes unstable where this critical capillary number inversely scales with the ambient pressure. The contact line instabilities at relatively low We numbers ( We ∼ O(10)) observed in this study provide insight into the conventional understanding of hydrodynamic instabilities under drop impact which usually require We ≫ 10.

Design and Feasibility of an International Study Assessing the Prevalence of Contact Allergy to Fragrances in the General Population : The European Dermato-Epidemiology Network Fragrance Study

NARCIS (Netherlands)

Rossi, Marta; Coenraads, Pieter-Jan; Diepgen, Thomas; Svensson, Ake; Elsner, Peter; Goncalo, Margarida; Bruze, Magnus; Naldi, Luigi

2010-01-01

Background/Aims: Data on contact allergy to fragrances in the general population are limited. Data from allergological services suggest that the frequency of contact allergy to fragrances is increasing. The European Dermato-Epidemiology Network (EDEN) Fragrance Study aims to obtain reliable data on

Better sales networks.

Science.gov (United States)

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.

Information Diffusion in Facebook-Like Social Networks Under Information Overload

Science.gov (United States)

Li, Pei; Xing, Kai; Wang, Dapeng; Zhang, Xin; Wang, Hui

2013-07-01

Research on social networks has received remarkable attention, since many people use social networks to broadcast information and stay connected with their friends. However, due to the information overload in social networks, it becomes increasingly difficult for users to find useful information. This paper takes Facebook-like social networks into account, and models the process of information diffusion under information overload. The term view scope is introduced to model the user information-processing capability under information overload, and the average number of times a message appears in view scopes after it is generated is proposed to characterize the information diffusion efficiency. Through theoretical analysis, we find that factors such as network structure and view scope number have no impact on the information diffusion efficiency, which is a surprising result. To verify the results, we conduct simulations and provide the simulation results, which are consistent with the theoretical analysis results perfectly.

A statistical network analysis of the HIV/AIDS epidemics in Cuba

OpenAIRE

Clémençon, Stéphan; De Arazoza, Hector; Rossi, Fabrice; Tran, Viet Chi

2014-01-01

International audience; The Cuban contact-tracing detection system set up in 1986 allowed the reconstruction and analysis of the sexual network underlying the epidemic (5,389 vertices and 4,073 edges, giant component of 2,386 nodes and 3,168 edges), shedding light onto the spread of HIV and the role of contact-tracing. Clustering based on modularity optimization provides a better visualization and understanding of the network, in combination with the study of covariates. The graph has a globa...

Vibration Analysis of a Tire in Ground Contact under Varied Conditions

Directory of Open Access Journals (Sweden)

Karakus Murat

2017-03-01

Full Text Available The effect of three different factors, which are inflation pressure, vertical load and coefficient of friction on the natural frequencies of a tire (175/70 R13 has been studied. A three dimensional tire model is constructed, using four different material properties and parts in the tire. Mechanical properties of the composite parts are evaluated. After investigating the free vibration, contact analysis is carried out. A concrete block and the tire are modelled together, using three different coefficients of friction. Experiments are run under certain conditions to check the accuracy of the numerical model. The natural frequencies are measured to describe free vibration and vibration of the tire contacted by ground, using a damping monitoring method. It is seen, that experimental and numerical results are in good agreement. On the other hand, investigating the impact of three different factors together is quite difficult on the natural frequencies. When some of these factors are assumed to be constant and the variables are taken one by one, it is easier to assess the effects.

Contact isotopic- and contact ion-exchange between two adsorbents

International Nuclear Information System (INIS)

Bunzl, K.; Mohan, R.; Haimerl, M.

1975-01-01

The kinetics of contact ion exchange processes between an ion exchange membrane and resin ion exchange beads, stirred in pure water, was investigated. A general criterion was derived, which indicates whether diffusion of the ions between the intermingling electric double layers or the collision frequency between the two adsorbents is the rate dermining step. Since the latter process proved to be rate controlling under our experimental conditions, the corresponding rate equations were derived under various initial and boundary conditions. Experimentally, the kinetics of contact isotopic exchange of Cs + - and Na + -ions as well as of the reverse contact ion exchange process of Cs + -versus Na + -ions were investigated by using Na 22 and Cs 137 radioisotopes. The experiments reveal in quantitative accord with the theory that the rate of collision controlled contact ion exchange processes depends mainly on the 'exchange coefficient', the separation factor and the collision frequency. While the latter two quantities were determined independently by separate experiments, the 'exchange coefficient' was evaluated from a contact isotopic exchange experiment. (orig.) [de

The Analysis of Three-Body Contact Temperature under the Different Third Particle Size, Density, and Value of Friction

Directory of Open Access Journals (Sweden)

Horng-Wen Wu

2017-10-01

Full Text Available Recently, many studies have investigated the friction, wear, and temperature characteristics of the interface between two relative movements. Such analyses often set the coefficient of friction as a fixed value and are analyzed in cases of two-body contact; however, the interface is often a three-body contact and the coefficient of friction varies depending on the operating conditions. This is a significant error in the analysis of contact characteristics, therefore, in this study, the actual interface and the change of the coefficient of friction were analyzed based on three-body micro-contact theory where the contact temperature was also analyzed and the difference between the generally assumed values were compared. The results showed that under three-body contact, the coefficient of total friction increased with an increase in particle size; and at a different particle size and area density of particles, the surface contact temperature increased with the plasticity index and load increases, and the particle contact temperature increased with the increasing particle size. The surface temperature rise was mainly affected by the ratio of the average temperature between surface 1 and surface 2 to the multiplication between the 100th root of the area density of particles and the square root of the equivalent surface roughness (Ts1s2_ave*/ηa0.01σ0.5 and the ratio of the 10th root of the mean particle diameter to the 100th root of the equivalent surface roughness (xa0.1/σ0.001. Particle temperature was mainly affected by the ratio of the 10th root of the mean particle diameter to the 100th root of the equivalent surface roughness (xa0.1/σ0.001 and the area density of particles ηa. Our study indicated that when the contact of surface with surface and the contact of the particles with the surface, the resulting heat balance was assigned to the particles and the surface in a three-body contact situation. Under this contact behavior, it could avoid

A study on the evolution of crack networks under thermal fatigue loading

International Nuclear Information System (INIS)

Kamaya, Masayuki; Taheri, Said

2008-01-01

The crack network is a typical cracking morphology caused by thermal fatigue loading. It was pointed out that the crack network appeared under relatively small temperature fluctuations and did not grow deeply. In this study, the mechanism of evolution of crack network and its influence on crack growth was examined by numerical calculation. First, the stress field near two interacting cracks was investigated. It was shown that there are stress-concentration and stress-shielding zones around interacting cracks, and that cracks can form a network under the bi-axial stress condition. Secondly, a Monte Carlo simulation was developed in order to simulate the initiation and growth of cracks under thermal fatigue loading and the evolution of the crack network. The local stress field formed by pre-existing cracks was evaluated by the body force method and its role in the initiation and growth of cracks was considered. The simulation could simulate the evolution of the crack network and change in number of cracks observed in the experiments. It was revealed that reduction in the stress intensity factor due to stress feature in the depth direction under high cycle thermal fatigue loading plays an important role in the evolution of the crack network and that mechanical interaction between cracks in the network affects initiation rather than growth of cracks. The crack network appears only when the crack growth in the depth direction is interrupted. It was concluded that the emergence of the crack network is preferable for the structural integrity of cracked components

Brain network response underlying decisions about abstract reinforcers.

Science.gov (United States)

Mills-Finnerty, Colleen; Hanson, Catherine; Hanson, Stephen Jose

2014-12-01

Decision making studies typically use tasks that involve concrete action-outcome contingencies, in which subjects do something and get something. No studies have addressed decision making involving abstract reinforcers, where there are no action-outcome contingencies and choices are entirely hypothetical. The present study examines these kinds of choices, as well as whether the same biases that exist for concrete reinforcer decisions, specifically framing effects, also apply during abstract reinforcer decisions. We use both General Linear Model as well as Bayes network connectivity analysis using the Independent Multi-sample Greedy Equivalence Search (IMaGES) algorithm to examine network response underlying choices for abstract reinforcers under positive and negative framing. We find for the first time that abstract reinforcer decisions activate the same network of brain regions as concrete reinforcer decisions, including the striatum, insula, anterior cingulate, and VMPFC, results that are further supported via comparison to a meta-analysis of decision making studies. Positive and negative framing activated different parts of this network, with stronger activation in VMPFC during negative framing and in DLPFC during positive, suggesting different decision making pathways depending on frame. These results were further clarified using connectivity analysis, which revealed stronger connections between anterior cingulate, insula, and accumbens during negative framing compared to positive. Taken together, these results suggest that not only do abstract reinforcer decisions rely on the same brain substrates as concrete reinforcers, but that the response underlying framing effects on abstract reinforcers also resemble those for concrete reinforcers, specifically increased limbic system connectivity during negative frames. Copyright © 2014 Elsevier Inc. All rights reserved.

Robustness Analysis of Real Network Topologies Under Multiple Failure Scenarios

DEFF Research Database (Denmark)

Manzano, M.; Marzo, J. L.; Calle, E.

2012-01-01

on topological characteristics. Recently approaches also consider the services supported by such networks. In this paper we carry out a robustness analysis of five real backbone telecommunication networks under defined multiple failure scenarios, taking into account the consequences of the loss of established......Nowadays the ubiquity of telecommunication networks, which underpin and fulfill key aspects of modern day living, is taken for granted. Significant large-scale failures have occurred in the last years affecting telecommunication networks. Traditionally, network robustness analysis has been focused...... connections. Results show which networks are more robust in response to a specific type of failure....

CDMA coverage under mobile heterogeneous network load

NARCIS (Netherlands)

Saban, D.; van den Berg, Hans Leo; Boucherie, Richardus J.; Endrayanto, A.I.

2002-01-01

We analytically investigate coverage (determined by the uplink) under non-homogeneous and moving traffic load of third generation UMTS mobile networks. In particular, for different call assignment policies, we investigate cell breathing and the movement of the coverage gap occurring between cells

Analysis of Network Topologies Underlying Ethylene Growth Response Kinetics

Directory of Open Access Journals (Sweden)

Aaron M. Prescott

2016-08-01

underlying ethylene signaling. Analysis of each network topology results in predictions about changes that occur in network components that can be experimentally tested to give insights into which, if either, network underlies ethylene responses.

Analysis of Network Topologies Underlying Ethylene Growth Response Kinetics.

Science.gov (United States)

Prescott, Aaron M; McCollough, Forest W; Eldreth, Bryan L; Binder, Brad M; Abel, Steven M

2016-01-01

Most models for ethylene signaling involve a linear pathway. However, measurements of seedling growth kinetics when ethylene is applied and removed have resulted in more complex network models that include coherent feedforward, negative feedback, and positive feedback motifs. The dynamical responses of the proposed networks have not been explored in a quantitative manner. Here, we explore (i) whether any of the proposed models are capable of producing growth-response behaviors consistent with experimental observations and (ii) what mechanistic roles various parts of the network topologies play in ethylene signaling. To address this, we used computational methods to explore two general network topologies: The first contains a coherent feedforward loop that inhibits growth and a negative feedback from growth onto itself (CFF/NFB). In the second, ethylene promotes the cleavage of EIN2, with the product of the cleavage inhibiting growth and promoting the production of EIN2 through a positive feedback loop (PFB). Since few network parameters for ethylene signaling are known in detail, we used an evolutionary algorithm to explore sets of parameters that produce behaviors similar to experimental growth response kinetics of both wildtype and mutant seedlings. We generated a library of parameter sets by independently running the evolutionary algorithm many times. Both network topologies produce behavior consistent with experimental observations, and analysis of the parameter sets allows us to identify important network interactions and parameter constraints. We additionally screened these parameter sets for growth recovery in the presence of sub-saturating ethylene doses, which is an experimentally-observed property that emerges in some of the evolved parameter sets. Finally, we probed simplified networks maintaining key features of the CFF/NFB and PFB topologies. From this, we verified observations drawn from the larger networks about mechanisms underlying ethylene

An approximate JKR solution for a general contact, including rough contacts

Science.gov (United States)

Ciavarella, M.

2018-05-01

In the present note, we suggest a simple closed form approximate solution to the adhesive contact problem under the so-called JKR regime. The derivation is based on generalizing the original JKR energetic derivation assuming calculation of the strain energy in adhesiveless contact, and unloading at constant contact area. The underlying assumption is that the contact area distributions are the same as under adhesiveless conditions (for an appropriately increased normal load), so that in general the stress intensity factors will not be exactly equal at all contact edges. The solution is simply that the indentation is δ =δ1 -√{ 2 wA‧ /P″ } where w is surface energy, δ1 is the adhesiveless indentation, A‧ is the first derivative of contact area and P‧‧ the second derivative of the load with respect to δ1. The solution only requires macroscopic quantities, and not very elaborate local distributions, and is exact in many configurations like axisymmetric contacts, but also sinusoidal waves contact and correctly predicts some features of an ideal asperity model used as a test case and not as a real description of a rough contact problem. The solution permits therefore an estimate of the full solution for elastic rough solids with Gaussian multiple scales of roughness, which so far was lacking, using known adhesiveless simple results. The result turns out to depend only on rms amplitude and slopes of the surface, and as in the fractal limit, slopes would grow without limit, tends to the adhesiveless result - although in this limit the JKR model is inappropriate. The solution would also go to adhesiveless result for large rms amplitude of roughness hrms, irrespective of the small scale details, and in agreement with common sense, well known experiments and previous models by the author.

Inferring the gene network underlying the branching of tomato inflorescence.

Directory of Open Access Journals (Sweden)

Laura Astola

Full Text Available The architecture of tomato inflorescence strongly affects flower production and subsequent crop yield. To understand the genetic activities involved, insight into the underlying network of genes that initiate and control the sympodial growth in the tomato is essential. In this paper, we show how the structure of this network can be derived from available data of the expressions of the involved genes. Our approach starts from employing biological expert knowledge to select the most probable gene candidates behind branching behavior. To find how these genes interact, we develop a stepwise procedure for computational inference of the network structure. Our data consists of expression levels from primary shoot meristems, measured at different developmental stages on three different genotypes of tomato. With the network inferred by our algorithm, we can explain the dynamics corresponding to all three genotypes simultaneously, despite their apparent dissimilarities. We also correctly predict the chronological order of expression peaks for the main hubs in the network. Based on the inferred network, using optimal experimental design criteria, we are able to suggest an informative set of experiments for further investigation of the mechanisms underlying branching behavior.

Design and feasibility of an international study assessing the prevalence of contact allergy to fragrances in the general population: the European Dermato-Epidemiology Network Fragrance Study

OpenAIRE

Rossi, M; Coenraads, PJ; Diepgen, T; Svensson, A; Elsner, P; Gonçalo, Margarida; Bruze, M; Naldi, L

2010-01-01

Background/Aims: Data on contact allergy to fragrances in the general population are limited. Data from allergological services suggest that the frequency of contact allergy to fragrances is increasing. The European Dermato-Epidemiology Network (EDEN) Fragrance Study aims to obtain reliable data on the prevalence of contact allergy to fragrances and other sensitizers of the European baseline series, in the general population of different geographical areas of Europe. We report the methodology...

Enhanced Contact Graph Routing (ECGR) MACHETE Simulation Model

Science.gov (United States)

Segui, John S.; Jennings, Esther H.; Clare, Loren P.

2013-01-01

Contact Graph Routing (CGR) for Delay/Disruption Tolerant Networking (DTN) space-based networks makes use of the predictable nature of node contacts to make real-time routing decisions given unpredictable traffic patterns. The contact graph will have been disseminated to all nodes before the start of route computation. CGR was designed for space-based networking environments where future contact plans are known or are independently computable (e.g., using known orbital dynamics). For each data item (known as a bundle in DTN), a node independently performs route selection by examining possible paths to the destination. Route computation could conceivably run thousands of times a second, so computational load is important. This work refers to the simulation software model of Enhanced Contact Graph Routing (ECGR) for DTN Bundle Protocol in JPL's MACHETE simulation tool. The simulation model was used for performance analysis of CGR and led to several performance enhancements. The simulation model was used to demonstrate the improvements of ECGR over CGR as well as other routing methods in space network scenarios. ECGR moved to using earliest arrival time because it is a global monotonically increasing metric that guarantees the safety properties needed for the solution's correctness since route re-computation occurs at each node to accommodate unpredicted changes (e.g., traffic pattern, link quality). Furthermore, using earliest arrival time enabled the use of the standard Dijkstra algorithm for path selection. The Dijkstra algorithm for path selection has a well-known inexpensive computational cost. These enhancements have been integrated into the open source CGR implementation. The ECGR model is also useful for route metric experimentation and comparisons with other DTN routing protocols particularly when combined with MACHETE's space networking models and Delay Tolerant Link State Routing (DTLSR) model.

Contact mechanical characteristics of Nb3Sn strands under transverse electromagnetic loads in the CICC cross-section

International Nuclear Information System (INIS)

Zhu Jiyue; Luo Wei; Zhou Youhe; Zheng Xiaojing

2012-01-01

This paper presents a new code for the two-dimensional discrete element method (DEM) and relevant simulations to quantitatively characterize the contact force behavior of the Nb 3 Sn strands in the ITER CICC cross-section under a transverse electromagnetic load. In order to obtain the essential parameters in the contact force model employed in the DEM, a simulation of the experiments conducted by Nijhuis et al (2004 IEEE Trans. Appl. Supercond. 14 1489–94) is first performed, where the load–displacement curve predicted by the code is in good agreement with the measurements. After that, the contact force chain between strands and its distribution is quantitatively analyzed by the code. It is found that the contact force distribution among strands is heterogeneous and strongly anisotropic. In other words, the force chain distribution, which determines the behavior of the assembly of strands with discrete media, and the distribution of area average magnitude of the contact force are obviously inhomogeneous. To describe this inhomogeneity, here, the probability density function (PDF) is used in the statistical analysis. The numerical results show that the PDFs of the magnitudes of the resultant contact force, normal contact force, and tangential contact force all decay with an exponential law, and that PDFs of the directions of the contact forces are all anisotropic and exhibit about six periodic changes in which the peak values in the direction parallel to the applied electromagnetic load are appreciably larger than the other peaks. (paper)

Asymmetrically interacting spreading dynamics on complex layered networks.

Science.gov (United States)

Wang, Wei; Tang, Ming; Yang, Hui; Younghae Do; Lai, Ying-Cheng; Lee, GyuWon

2014-05-29

The spread of disease through a physical-contact network and the spread of information about the disease on a communication network are two intimately related dynamical processes. We investigate the asymmetrical interplay between the two types of spreading dynamics, each occurring on its own layer, by focusing on the two fundamental quantities underlying any spreading process: epidemic threshold and the final infection ratio. We find that an epidemic outbreak on the contact layer can induce an outbreak on the communication layer, and information spreading can effectively raise the epidemic threshold. When structural correlation exists between the two layers, the information threshold remains unchanged but the epidemic threshold can be enhanced, making the contact layer more resilient to epidemic outbreak. We develop a physical theory to understand the intricate interplay between the two types of spreading dynamics.

A Nondominated Genetic Algorithm Procedure for Multiobjective Discrete Network Design under Demand Uncertainty

Directory of Open Access Journals (Sweden)

Bian Changzhi

2015-01-01

Full Text Available This paper addresses the multiobjective discrete network design problem under demand uncertainty. The OD travel demands are supposed to be random variables with the given probability distribution. The problem is formulated as a bilevel stochastic optimization model where the decision maker’s objective is to minimize the construction cost, the expectation, and the standard deviation of total travel time simultaneously and the user’s route choice is described using user equilibrium model on the improved network under all scenarios of uncertain demand. The proposed model generates globally near-optimal Pareto solutions for network configurations based on the Monte Carlo simulation and nondominated sorting genetic algorithms II. Numerical experiments implemented on Nguyen-Dupuis test network show trade-offs among construction cost, the expectation, and standard deviation of total travel time under uncertainty are obvious. Investment on transportation facilities is an efficient method to improve the network performance and reduce risk under demand uncertainty, but it has an obvious marginal decreasing effect.

Network flow model of force transmission in unbonded and bonded granular media.

Science.gov (United States)

Tordesillas, Antoinette; Tobin, Steven T; Cil, Mehmet; Alshibli, Khalid; Behringer, Robert P

2015-06-01

An established aspect of force transmission in quasistatic deformation of granular media is the existence of a dual network of strongly versus weakly loaded particles. Despite significant interest, the regulation of strong and weak forces through the contact network remains poorly understood. We examine this aspect of force transmission using data on microstructural fabric from: (I) three-dimensional discrete element models of grain agglomerates of bonded subspheres constructed from in situ synchrotron microtomography images of silica sand grains under unconfined compression and (II) two-dimensional assemblies of unbonded photoelastic circular disks submitted to biaxial compression under constant volume. We model force transmission as a network flow and solve the maximum flow-minimum cost (MFMC) problem, the solution to which yields a percolating subnetwork of contacts that transmits the "maximum flow" (i.e., the highest units of force) at "least cost" (i.e., the dissipated energy from such transmission). We find the MFMC describes a two-tier hierarchical architecture. At the local level, it encapsulates intraconnections between particles in individual force chains and in their conjoined 3-cycles, with the most common configuration having at least one force chain contact experiencing frustrated rotation. At the global level, the MFMC encapsulates interconnections between force chains. The MFMC can be used to predict most of the force chain particles without need for any information on contact forces, thereby suggesting the network flow framework may have potential broad utility in the modeling of force transmission in unbonded and bonded granular media.

EpiContactTrace: an R-package for contact tracing during livestock disease outbreaks and for risk-based surveillance.

Science.gov (United States)

Nöremark, Maria; Widgren, Stefan

2014-03-17

During outbreak of livestock diseases, contact tracing can be an important part of disease control. Animal movements can also be of relevance for risk-based surveillance and sampling, i.e. both when assessing consequences of introduction or likelihood of introduction. In many countries, animal movement data are collected with one of the major objectives to enable contact tracing. However, often an analytical step is needed to retrieve appropriate information for contact tracing or surveillance. In this study, an open source tool was developed to structure livestock movement data to facilitate contact-tracing in real time during disease outbreaks and for input in risk-based surveillance and sampling. The tool, EpiContactTrace, was written in the R-language and uses the network parameters in-degree, out-degree, ingoing contact chain and outgoing contact chain (also called infection chain), which are relevant for forward and backward tracing respectively. The time-frames for backward and forward tracing can be specified independently and search can be done on one farm at a time or for all farms within the dataset. Different outputs are available; datasets with network measures, contacts visualised in a map and automatically generated reports for each farm either in HTML or PDF-format intended for the end-users, i.e. the veterinary authorities, regional disease control officers and field-veterinarians. EpiContactTrace is available as an R-package at the R-project website (http://cran.r-project.org/web/packages/EpiContactTrace/). We believe this tool can help in disease control since it rapidly can structure essential contact information from large datasets. The reproducible reports make this tool robust and independent of manual compilation of data. The open source makes it accessible and easily adaptable for different needs.

Dynamics of the cell-cycle network under genome-rewiring perturbations

International Nuclear Information System (INIS)

Katzir, Yair; Elhanati, Yuval; Braun, Erez; Averbukh, Inna

2013-01-01

The cell-cycle progression is regulated by a specific network enabling its ordered dynamics. Recent experiments supported by computational models have shown that a core of genes ensures this robust cycle dynamics. However, much less is known about the direct interaction of the cell-cycle regulators with genes outside of the cell-cycle network, in particular those of the metabolic system. Following our recent experimental work, we present here a model focusing on the dynamics of the cell-cycle core network under rewiring perturbations. Rewiring is achieved by placing an essential metabolic gene exclusively under the regulation of a cell-cycle's promoter, forcing the cell-cycle network to function under a multitasking challenging condition; operating in parallel the cell-cycle progression and a metabolic essential gene. Our model relies on simple rate equations that capture the dynamics of the relevant protein–DNA and protein–protein interactions, while making a clear distinction between these two different types of processes. In particular, we treat the cell-cycle transcription factors as limited ‘resources’ and focus on the redistribution of resources in the network during its dynamics. This elucidates the sensitivity of its various nodes to rewiring interactions. The basic model produces the correct cycle dynamics for a wide range of parameters. The simplicity of the model enables us to study the interface between the cell-cycle regulation and other cellular processes. Rewiring a promoter of the network to regulate a foreign gene, forces a multitasking regulatory load. The higher the load on the promoter, the longer is the cell-cycle period. Moreover, in agreement with our experimental results, the model shows that different nodes of the network exhibit variable susceptibilities to the rewiring perturbations. Our model suggests that the topology of the cell-cycle core network ensures its plasticity and flexible interface with other cellular processes

Analysis of Heat Transfer in Power Split Device for Hybrid Electric Vehicle Using Thermal Network Method

Directory of Open Access Journals (Sweden)

Jixin Wang

2014-06-01

Full Text Available This paper presents a rational prediction of temperature field on the differential hybrid system (DHS based on the thermal network method (TNM. The whole thermal network model is built by considering both the contact thermal resistance between gasket and planet gear and the temperature effect on the physical property parameters of lubricant. The contact thermal resistance is obtained by using the concept of contact branch thermal resistance and G-W elastic model. By building an elaborate thermal network model and computing models for power losses and thermal resistances between components, the whole temperature field of DHS under typical operating condition is predicted. Results show that thermal network method can be effectively used to predict the temperature distribution and the rule of temperature variation, the surface roughness significantly affects contact thermal conduction, and the decrease in the thermal resistance of the natural convection between air and DHS housing can effectively improve the thermal environment of DHS.

Performance in wireless networks and industrial wireless networks on control processes in real time under industrial environments

Directory of Open Access Journals (Sweden)

Juan F. Monsalve-Posada

2015-01-01

Full Text Available The growing use of Ethernet networks on the industrial automation pyramid has led many companies to develop new devices to operate in requirements of this level, nowadays it is called Industrial Ethernet network, on the market there are various sensors and actuators to industrial scale equipped with this technology, many of these devices are very expensive. In this paper, the performance of two wireless networks is evaluated, the first network has conventional Ethernet devices, and the second network has Industrial Ethernet devices. For the process we vary four parameters such as distance, number of bytes, the signal to noise ratio, and the packet error rate, and then we measure delays and compare with metric statistics results, Box Plot graphs were used for the analysis. Finally, we conclude that under the parameters and conditions tested, wireless networks can serve as a communication system in control applications with allowable delays of up to 50 ms, in addition, the results show a better performance of Industrial Ethernet networks over conventional networks, with differences in the RTT of milliseconds. Therefore, it is recommended to establish what risk is for the process to control these delays to determine if the equipment conventional applies, since under certain features like humidity and temperature can operate properly for a considerable time and at lower cost than devices to Industrial Ethernet.

EPA Alternative Dispute Resolution Contacts

Science.gov (United States)

The success of EPA's ADR efforts depends on a network of talented and experienced professionals in Headquarters offices and EPA Regions. For Agency-wide ADR information, please contact the Conflict Prevention and Resolution Center.

Epidemics scenarios in the "Romantic network".

Directory of Open Access Journals (Sweden)

Alexsandro M Carvalho

Full Text Available The networks of sexual contacts together with temporal interactions play key roles in the spread of sexually transmitted infections. Unfortunately, data for this kind of network is scarce. One of the few exceptions, the "Romantic network", is a complete structure of a real sexual network in a high school. Based on many network measurements the authors of the work have concluded that it does not correspond to any other model network. Regarding the temporal structure, several studies indicate that relationship timing can have an effect on the diffusion throughout networks, as relationship order determines transmission routes. The aim is to check if the particular structure, static and dynamic, of the Romantic network is determinant for the propagation of an STI. We performed simulations in two scenarios: the static network where all contacts are available and the dynamic case where contacts evolve over time. In the static case, we compared the epidemic results in the Romantic network with some paradigmatic topologies. In the dynamic scenario, we considered the dynamics of formation of pairs in the Romantic network and we studied the propagation of the diseases. Our results suggest that although this real network cannot be labeled as a Watts-Strogatz network, it is, in regard to the propagation of an STI, very similar to a high disorder network. Additionally, we found that: the effect that any individual contacting an externally infected subject is to make the network closer to a fully connected one, the higher the contact degree of patient zero the faster the spread of the outbreaks, and the epidemic impact is proportional to the numbers of contacts per unit time. Finally, our simulations confirm that relationship timing severely reduced the final outbreak size, and also, show a clear correlation between the average degree and the outbreak size over time.

Projecting social contact matrices in 152 countries using contact surveys and demographic data.

Directory of Open Access Journals (Sweden)

Kiesha Prem

2017-09-01

Full Text Available Heterogeneities in contact networks have a major effect in determining whether a pathogen can become epidemic or persist at endemic levels. Epidemic models that determine which interventions can successfully prevent an outbreak need to account for social structure and mixing patterns. Contact patterns vary across age and locations (e.g. home, work, and school, and including them as predictors in transmission dynamic models of pathogens that spread socially will improve the models' realism. Data from population-based contact diaries in eight European countries from the POLYMOD study were projected to 144 other countries using a Bayesian hierarchical model that estimated the proclivity of age-and-location-specific contact patterns for the countries, using Markov chain Monte Carlo simulation. Household level data from the Demographic and Health Surveys for nine lower-income countries and socio-demographic factors from several on-line databases for 152 countries were used to quantify similarity of countries to estimate contact patterns in the home, work, school and other locations for countries for which no contact data are available, accounting for demographic structure, household structure where known, and a variety of metrics including workforce participation and school enrolment. Contacts are highly assortative with age across all countries considered, but pronounced regional differences in the age-specific contacts at home were noticeable, with more inter-generational contacts in Asian countries than in other settings. Moreover, there were variations in contact patterns by location, with work-place contacts being least assortative. These variations led to differences in the effect of social distancing measures in an age structured epidemic model. Contacts have an important role in transmission dynamic models that use contact rates to characterize the spread of contact-transmissible diseases. This study provides estimates of mixing patterns for

Projecting social contact matrices in 152 countries using contact surveys and demographic data.

Science.gov (United States)

Prem, Kiesha; Cook, Alex R; Jit, Mark

2017-09-01

Heterogeneities in contact networks have a major effect in determining whether a pathogen can become epidemic or persist at endemic levels. Epidemic models that determine which interventions can successfully prevent an outbreak need to account for social structure and mixing patterns. Contact patterns vary across age and locations (e.g. home, work, and school), and including them as predictors in transmission dynamic models of pathogens that spread socially will improve the models' realism. Data from population-based contact diaries in eight European countries from the POLYMOD study were projected to 144 other countries using a Bayesian hierarchical model that estimated the proclivity of age-and-location-specific contact patterns for the countries, using Markov chain Monte Carlo simulation. Household level data from the Demographic and Health Surveys for nine lower-income countries and socio-demographic factors from several on-line databases for 152 countries were used to quantify similarity of countries to estimate contact patterns in the home, work, school and other locations for countries for which no contact data are available, accounting for demographic structure, household structure where known, and a variety of metrics including workforce participation and school enrolment. Contacts are highly assortative with age across all countries considered, but pronounced regional differences in the age-specific contacts at home were noticeable, with more inter-generational contacts in Asian countries than in other settings. Moreover, there were variations in contact patterns by location, with work-place contacts being least assortative. These variations led to differences in the effect of social distancing measures in an age structured epidemic model. Contacts have an important role in transmission dynamic models that use contact rates to characterize the spread of contact-transmissible diseases. This study provides estimates of mixing patterns for societies for which

The Network Structure Underlying the Earth Observation Assessment

Science.gov (United States)

Vitkin, S.; Doane, W. E. J.; Mary, J. C.

2017-12-01

The Earth Observations Assessment (EOA 2016) is a multiyear project designed to assess the effectiveness of civil earth observation data sources (instruments, sensors, models, etc.) on societal benefit areas (SBAs) for the United States. Subject matter experts (SMEs) provided input and scored how data sources inform products, product groups, key objectives, SBA sub-areas, and SBAs in an attempt to quantify the relationships between data sources and SBAs. The resulting data were processed by Integrated Applications Incorporated (IAI) using MITRE's PALMA software to create normalized relative impact scores for each of these relationships. However, PALMA processing obscures the natural network representation of the data. Any network analysis that might identify patterns of interaction among data sources, products, and SBAs is therefore impossible. Collaborating with IAI, we cleaned and recreated a network from the original dataset. Using R and Python we explore the underlying structure of the network and apply frequent itemset mining algorithms to identify groups of data sources and products that interact. We reveal interesting patterns and relationships in the EOA dataset that were not immediately observable from the EOA 2016 report and provide a basis for further exploration of the EOA network dataset.

Electric contact arcing

International Nuclear Information System (INIS)

Cuthrell, R.E.

1976-01-01

Electrical contacts must function properly in many types of components used in nuclear weapon systems. Design, application, and testing of these components require detailed knowledge of chemical and physical phenomena associated with stockpile storage, stockpile testing, and operation. In the past, investigation of these phenomena has led to significant discoveries on the effects of surface contaminants, friction and wear, and the mechanics of closure on contact performance. A recent investigation of contact arcing phenomena which revealed that, preceding contact closure, arcs may occur at voltages lower than had been previously known is described. This discovery is important, since arcing may damage contacts, and repetitive testing of contacts performed as part of a quality assurance program might produce cumulative damage that would yield misleading life-test data and could prevent proper operation of the contacts at some time in the future. This damage can be avoided by determining the conditions under which arcing occurs, and ensuring that these conditions are avoided in contact testing

Vulnerability of complex networks under intentional attack with incomplete information

International Nuclear Information System (INIS)

Wu, J; Deng, H Z; Tan, Y J; Zhu, D Z

2007-01-01

We study the vulnerability of complex networks under intentional attack with incomplete information, which means that one can only preferentially attack the most important nodes among a local region of a network. The known random failure and the intentional attack are two extreme cases of our study. Using the generating function method, we derive the exact value of the critical removal fraction f c of nodes for the disintegration of networks and the size of the giant component. To validate our model and method, we perform simulations of intentional attack with incomplete information in scale-free networks. We show that the attack information has an important effect on the vulnerability of scale-free networks. We also demonstrate that hiding a fraction of the nodes information is a cost-efficient strategy for enhancing the robustness of complex networks

Inference of Transmission Network Structure from HIV Phylogenetic Trees.

Science.gov (United States)

Giardina, Federica; Romero-Severson, Ethan Obie; Albert, Jan; Britton, Tom; Leitner, Thomas

2017-01-01

Phylogenetic inference is an attractive means to reconstruct transmission histories and epidemics. However, there is not a perfect correspondence between transmission history and virus phylogeny. Both node height and topological differences may occur, depending on the interaction between within-host evolutionary dynamics and between-host transmission patterns. To investigate these interactions, we added a within-host evolutionary model in epidemiological simulations and examined if the resulting phylogeny could recover different types of contact networks. To further improve realism, we also introduced patient-specific differences in infectivity across disease stages, and on the epidemic level we considered incomplete sampling and the age of the epidemic. Second, we implemented an inference method based on approximate Bayesian computation (ABC) to discriminate among three well-studied network models and jointly estimate both network parameters and key epidemiological quantities such as the infection rate. Our ABC framework used both topological and distance-based tree statistics for comparison between simulated and observed trees. Overall, our simulations showed that a virus time-scaled phylogeny (genealogy) may be substantially different from the between-host transmission tree. This has important implications for the interpretation of what a phylogeny reveals about the underlying epidemic contact network. In particular, we found that while the within-host evolutionary process obscures the transmission tree, the diversification process and infectivity dynamics also add discriminatory power to differentiate between different types of contact networks. We also found that the possibility to differentiate contact networks depends on how far an epidemic has progressed, where distance-based tree statistics have more power early in an epidemic. Finally, we applied our ABC inference on two different outbreaks from the Swedish HIV-1 epidemic.

Noneczematous Contact Dermatitis

Science.gov (United States)

Foti, Caterina; Vestita, Michelangelo; Angelini, Gianni

2013-01-01

Irritant or allergic contact dermatitis usually presents as an eczematous process, clinically characterized by erythematoedematovesicous lesions with intense itching in the acute phase. Such manifestations become erythematous-scaly as the condition progresses to the subacute phase and papular-hyperkeratotic in the chronic phase. Not infrequently, however, contact dermatitis presents with noneczematous features. The reasons underlying this clinical polymorphism lie in the different noxae and contact modalities, as well as in the individual susceptibility and the various targeted cutaneous structures. The most represented forms of non-eczematous contact dermatitis include the erythema multiforme-like, the purpuric, the lichenoid, and the pigmented kinds. These clinical entities must obviously be discerned from the corresponding “pure” dermatitis, which are not associated with contact with exogenous agents. PMID:24109520

Temporal network epidemiology

CERN Document Server

Holme, Petter

2017-01-01

This book covers recent developments in epidemic process models and related data on temporally varying networks. It is widely recognized that contact networks are indispensable for describing, understanding, and intervening to stop the spread of infectious diseases in human and animal populations; “network epidemiology” is an umbrella term to describe this research field. More recently, contact networks have been recognized as being highly dynamic. This observation, also supported by an increasing amount of new data, has led to research on temporal networks, a rapidly growing area. Changes in network structure are often informed by epidemic (or other) dynamics, in which case they are referred to as adaptive networks. This volume gathers contributions by prominent authors working in temporal and adaptive network epidemiology, a field essential to understanding infectious diseases in real society.

Node vulnerability of water distribution networks under cascading failures

International Nuclear Information System (INIS)

Shuang, Qing; Zhang, Mingyuan; Yuan, Yongbo

2014-01-01

Water distribution networks (WDNs) are important in modern lifeline system. Its stability and reliability are critical for guaranteeing high living quality and continuous operation of urban functions. The aim of this paper is to evaluate the nodal vulnerability of WDNs under cascading failures. Vulnerability is defined to analyze the effects of the consequent failures. A cascading failure is a step-by-step process which is quantitatively investigated by numerical simulation with intentional attack. Monitored pressures in different nodes and flows in different pipes have been used to estimate the network topological structure and the consequences of nodal failure. Based on the connectivity loss of topological structure, the nodal vulnerability has been evaluated. A load variation function is established to record the nodal failure reason and describe the relative differences between the load and the capacity. The proposed method is validated by an illustrative example. The results revealed that the network vulnerability should be evaluated with the consideration of hydraulic analysis and network topology. In the case study, 70.59% of the node failures trigger the cascading failures with different failure processes. It is shown that the cascading failures result in severe consequences in WDNs. - Highlights: • The aim of this paper is to evaluate the nodal vulnerability of water distribution networks under cascading failures. • Monitored pressures and flows have been used to estimate the network topological structure and the consequences of nodal failure. • Based on the connectivity loss of topological structure, the nodal vulnerability has been evaluated. • A load variation function is established to record the failure reason and describe the relative differences between load and capacity. • The results show that 70.59% of the node failures trigger the cascading failures with different failure processes

Epidemic Survivability: Characterizing Networks Under Epidemic-like Failure Propagation Scenarios

DEFF Research Database (Denmark)

Manzano, Marc; Calle, Eusebi; Ripoll, Jordi

2013-01-01

Epidemics theory has been used in different contexts in order to describe the propagation of diseases, human interactions or natural phenomena. In computer science, virus spreading has been also characterized using epidemic models. Although in the past the use of epidemic models...... in telecommunication networks has not been extensively considered, nowadays, with the increasing computation capacity and complexity of operating systems of modern network devices (routers, switches, etc.), the study of possible epidemic-like failure scenarios must be taken into account. When epidemics occur......, such as in other multiple failure scenarios, identifying the level of vulnerability offered by a network is one of the main challenges. In this paper, we present epidemic survivability, a new network measure that describes the vulnerability of each node of a network under a specific epidemic intensity. Moreover...

Wireless Networks under a Backoff Attack: A Game Theoretical Perspective.

Science.gov (United States)

Parras, Juan; Zazo, Santiago

2018-01-30

We study a wireless sensor network using CSMA/CA in the MAC layer under a backoff attack: some of the sensors of the network are malicious and deviate from the defined contention mechanism. We use Bianchi's network model to study the impact of the malicious sensors on the total network throughput, showing that it causes the throughput to be unfairly distributed among sensors. We model this conflict using game theory tools, where each sensor is a player. We obtain analytical solutions and propose an algorithm, based on Regret Matching, to learn the equilibrium of the game with an arbitrary number of players. Our approach is validated via simulations, showing that our theoretical predictions adjust to reality.

Supply chain network design under uncertainty

DEFF Research Database (Denmark)

Govindan, Kannan; Fattahi, Mohammad; Keyvanshokooh, Esmaeil

2017-01-01

Supply chain network design (SCND) is one of the most crucial planning problems in supply chain management (SCM). Nowadays, design decisions should be viable enough to function well under complex and uncertain business environments for many years or decades. Therefore, it is essential to make...... programming, risk-averse stochastic programming, robust optimization, and fuzzy mathematical programming are explored in terms of mathematical modeling and solution approaches. Finally, the drawbacks and missing aspects of the related literature are highlighted and a list of potential issues for future...

Capacity planning of link restorable optical networks under dynamic change of traffic

Science.gov (United States)

Ho, Kwok Shing; Cheung, Kwok Wai

2005-11-01

Future backbone networks shall require full-survivability and support dynamic changes of traffic demands. The Generalized Survivable Networks (GSN) was proposed to meet these challenges. GSN is fully-survivable under dynamic traffic demand changes, so it offers a practical and guaranteed characterization framework for ASTN / ASON survivable network planning and bandwidth-on-demand resource allocation 4. The basic idea of GSN is to incorporate the non-blocking network concept into the survivable network models. In GSN, each network node must specify its I/O capacity bound which is taken as constraints for any allowable traffic demand matrix. In this paper, we consider the following generic GSN network design problem: Given the I/O bounds of each network node, find a routing scheme (and the corresponding rerouting scheme under failure) and the link capacity assignment (both working and spare) which minimize the cost, such that any traffic matrix consistent with the given I/O bounds can be feasibly routed and it is single-fault tolerant under the link restoration scheme. We first show how the initial, infeasible formal mixed integer programming formulation can be transformed into a more feasible problem using the duality transformation of the linear program. Then we show how the problem can be simplified using the Lagrangian Relaxation approach. Previous work has outlined a two-phase approach for solving this problem where the first phase optimizes the working capacity assignment and the second phase optimizes the spare capacity assignment. In this paper, we present a jointly optimized framework for dimensioning the survivable optical network with the GSN model. Experiment results show that the jointly optimized GSN can bring about on average of 3.8% cost savings when compared with the separate, two-phase approach. Finally, we perform a cost comparison and show that GSN can be deployed with a reasonable cost.

Optimizing targeted vaccination across cyber-physical networks: an empirically based mathematical simulation study.

Science.gov (United States)

Mones, Enys; Stopczynski, Arkadiusz; Pentland, Alex 'Sandy'; Hupert, Nathaniel; Lehmann, Sune

2018-01-01

Targeted vaccination, whether to minimize the forward transmission of infectious diseases or their clinical impact, is one of the 'holy grails' of modern infectious disease outbreak response, yet it is difficult to achieve in practice due to the challenge of identifying optimal targets in real time. If interruption of disease transmission is the goal, targeting requires knowledge of underlying person-to-person contact networks. Digital communication networks may reflect not only virtual but also physical interactions that could result in disease transmission, but the precise overlap between these cyber and physical networks has never been empirically explored in real-life settings. Here, we study the digital communication activity of more than 500 individuals along with their person-to-person contacts at a 5-min temporal resolution. We then simulate different disease transmission scenarios on the person-to-person physical contact network to determine whether cyber communication networks can be harnessed to advance the goal of targeted vaccination for a disease spreading on the network of physical proximity. We show that individuals selected on the basis of their closeness centrality within cyber networks (what we call 'cyber-directed vaccination') can enhance vaccination campaigns against diseases with short-range (but not full-range) modes of transmission. © 2018 The Author(s).

Elastic contact mechanics: percolation of the contact area and fluid squeeze-out.

Science.gov (United States)

Persson, B N J; Prodanov, N; Krick, B A; Rodriguez, N; Mulakaluri, N; Sawyer, W G; Mangiagalli, P

2012-01-01

The dynamics of fluid flow at the interface between elastic solids with rough surfaces depends sensitively on the area of real contact, in particular close to the percolation threshold, where an irregular network of narrow flow channels prevails. In this paper, numerical simulation and experimental results for the contact between elastic solids with isotropic and anisotropic surface roughness are compared with the predictions of a theory based on the Persson contact mechanics theory and the Bruggeman effective medium theory. The theory predictions are in good agreement with the experimental and numerical simulation results and the (small) deviation can be understood as a finite-size effect. The fluid squeeze-out at the interface between elastic solids with randomly rough surfaces is studied. We present results for such high contact pressures that the area of real contact percolates, giving rise to sealed-off domains with pressurized fluid at the interface. The theoretical predictions are compared to experimental data for a simple model system (a rubber block squeezed against a flat glass plate), and for prefilled syringes, where the rubber plunger stopper is lubricated by a high-viscosity silicon oil to ensure functionality of the delivery device. For the latter system we compare the breakloose (or static) friction, as a function of the time of stationary contact, to the theory prediction.

Formal Models of the Network Co-occurrence Underlying Mental Operations.

Science.gov (United States)

Bzdok, Danilo; Varoquaux, Gaël; Grisel, Olivier; Eickenberg, Michael; Poupon, Cyril; Thirion, Bertrand

2016-06-01

Systems neuroscience has identified a set of canonical large-scale networks in humans. These have predominantly been characterized by resting-state analyses of the task-unconstrained, mind-wandering brain. Their explicit relationship to defined task performance is largely unknown and remains challenging. The present work contributes a multivariate statistical learning approach that can extract the major brain networks and quantify their configuration during various psychological tasks. The method is validated in two extensive datasets (n = 500 and n = 81) by model-based generation of synthetic activity maps from recombination of shared network topographies. To study a use case, we formally revisited the poorly understood difference between neural activity underlying idling versus goal-directed behavior. We demonstrate that task-specific neural activity patterns can be explained by plausible combinations of resting-state networks. The possibility of decomposing a mental task into the relative contributions of major brain networks, the "network co-occurrence architecture" of a given task, opens an alternative access to the neural substrates of human cognition.

Experimental investigation on the electrical contact behavior of rolling contact connector

Energy Technology Data Exchange (ETDEWEB)

Chen, Junxing; Yang, Fei, E-mail: yfei2007@mail.xjtu.edu.cn; Luo, Kaiyu; Zhu, Mingliang; Wu, Yi; Rong, Mingzhe [State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049 (China)

2015-12-15

Rolling contact connector (RCC) is a new technology utilized in high performance electric power transfer systems with one or more rotating interfaces, such as radars, satellites, wind generators, and medical computed tomography machines. Rolling contact components are used in the RCC instead of traditional sliding contacts to transfer electrical power and/or signal. Since the requirement of the power transmission is increasing in these years, the rolling electrical contact characteristics become more and more important for the long-life design of RCC. In this paper, a typical form of RCC is presented. A series of experimental work are carried out to investigate the rolling electrical contact characteristics during its lifetime. The influence of a variety of factors on the electrical contact degradation behavior of RCC is analyzed under both vacuum and air environment. Based on the surface morphology and elemental composition changes in the contact zone, which are assessed by field emission scanning electron microscope and confocal laser scanning microscope, the mechanism of rolling electrical contact degradation is discussed.

Measuring The Contact Resistances Of Photovoltaic Cells

Science.gov (United States)

Burger, D. R.

1985-01-01

Simple method devised to measure contact resistances of photovoltaic solar cells. Method uses readily available equipment and applicable at any time during life of cell. Enables evaluation of cell contact resistance, contact-end resistance, contact resistivity, sheet resistivity, and sheet resistivity under contact.

Contact technique and concussions in the South African under-18 Coca-Cola Craven Week Rugby tournament.

Science.gov (United States)

Hendricks, Sharief; O'connor, Sam; Lambert, Michael; Brown, James; Burger, Nicholas; Mc Fie, Sarah; Readhead, Clint; Viljoen, Wayne

2015-01-01

In rugby union, understanding the techniques and events leading to concussions is important because of the nature of the injury and the severity and potential long-term consequences, particularly in junior players. Proper contact technique is a prerequisite for successful participation in rugby and is a major factor associated with injury. However, the execution of proper contact technique and its relationship to injury has yet to be studied in matches. Therefore, the aim of this study was to compare contact techniques leading to concussion with a representative sample of similarly matched non-injury (NI) contact events. Injury surveillance was conducted at the 2011-2013 under-18 Craven Week Rugby tournaments. Video footage of 10 concussive events (5 tackle, 4 ruck and 1 aerial collision) and 83 NI events were identified (19 tackle, 61 ruck and 3 aerial collisions). Thereafter, each phase of play was analysed using standardised technical proficiency criteria. Overall score for ruck proficiency in concussive events was 5.67 (out of a total of 15) vs. 6.98 for NI events (n = 54) (effect size = 0.52, small). Overall average score for tackler proficiency was 7.25 (n = 4) and 6.67 (n = 15) for injury and NI tackles, respectively (out of 16) (effect size = 0.19, trivial). This is the first study to compare concussion injury contact technique to a player-matched sample of NI contact techniques. Certain individual technical criteria had an effect towards an NI outcome, and others had an effect towards a concussive event, highlighting that failure to execute certain techniques may substantially increase the opportunity for concussion.

Incident Type 2 Diabetes Risk is Influenced by Obesity and Diabetes in Social Contacts: a Social Network Analysis.

Science.gov (United States)

Raghavan, Sridharan; Pachucki, Mark C; Chang, Yuchiao; Porneala, Bianca; Fox, Caroline S; Dupuis, Josée; Meigs, James B

2016-10-01

Obesity and diabetes family history are the two strongest risk factors for type 2 diabetes (T2D). Prior work shows that an individual's obesity risk is associated with obesity in social contacts, but whether T2D risk follows similar patterns is unknown. We aimed to estimate the relationship between obesity or diabetes in an individual's social contacts and his/her T2D risk. We hypothesized that obesity and diabetes in social contacts would increase an individual's T2D risk. This was a retrospective analysis of the community-based Framingham Offspring Study (FOS). FOS participants with T2D status, height and weight, and at least one social contact were eligible for this study (n = 4797 at Exam 1). Participants' interpersonal ties, cardiometabolic and demographic variables were available at eight exams from 1971 to 2008, and a T2D additive polygenic risk score was measured at the fifth exam. Primary exposures were T2D (fasting glucose ≥ 7 mmol/L or taking diabetes medications) and obesity status (BMI ≥ 30 kg/m(2)) of social contacts at a prior exam. Primary outcome was incident T2D in participants. Incident T2D was associated with having a social contact with diabetes (OR 1.32, p = 0.004) or with obesity (OR 1.21, p = 0.004). In stratified analyses, incident T2D was associated with diabetes in siblings (OR 1.64, p = 0.001) and obesity in spouses (OR 1.54, p = 0.0004). The associations between diabetes and obesity in social contacts and an individual's incident diabetes risk were stronger in individuals with a high diabetes genetic risk score. T2D and obesity in social contacts, particularly siblings and spouses, were associated with an individual's risk of incident diabetes even after accounting for parental T2D history. Assessing risk factors in an individual's siblings and spouses can inform T2D risk; furthermore, social network based lifestyle interventions involving spouses and siblings might be a novel T2D prevention approach.

Epidemic spreading in networks with nonrandom long-range interactions.

Science.gov (United States)

Estrada, Ernesto; Kalala-Mutombo, Franck; Valverde-Colmeiro, Alba

2011-09-01

An "infection," understood here in a very broad sense, can be propagated through the network of social contacts among individuals. These social contacts include both "close" contacts and "casual" encounters among individuals in transport, leisure, shopping, etc. Knowing the first through the study of the social networks is not a difficult task, but having a clear picture of the network of casual contacts is a very hard problem in a society of increasing mobility. Here we assume, on the basis of several pieces of empirical evidence, that the casual contacts between two individuals are a function of their social distance in the network of close contacts. Then, we assume that we know the network of close contacts and infer the casual encounters by means of nonrandom long-range (LR) interactions determined by the social proximity of the two individuals. This approach is then implemented in a susceptible-infected-susceptible (SIS) model accounting for the spread of infections in complex networks. A parameter called "conductance" controls the feasibility of those casual encounters. In a zero conductance network only contagion through close contacts is allowed. As the conductance increases the probability of having casual encounters also increases. We show here that as the conductance parameter increases, the rate of propagation increases dramatically and the infection is less likely to die out. This increment is particularly marked in networks with scale-free degree distributions, where infections easily become epidemics. Our model provides a general framework for studying epidemic spreading in networks with arbitrary topology with and without casual contacts accounted for by means of LR interactions.

Wireless Networks under a Backoff Attack: A Game Theoretical Perspective

Directory of Open Access Journals (Sweden)

Juan Parras

2018-01-01

Full Text Available We study a wireless sensor network using CSMA/CA in the MAC layer under a backoff attack: some of the sensors of the network are malicious and deviate from the defined contention mechanism. We use Bianchi’s network model to study the impact of the malicious sensors on the total network throughput, showing that it causes the throughput to be unfairly distributed among sensors. We model this conflict using game theory tools, where each sensor is a player. We obtain analytical solutions and propose an algorithm, based on Regret Matching, to learn the equilibrium of the game with an arbitrary number of players. Our approach is validated via simulations, showing that our theoretical predictions adjust to reality.

Double Contact During Drop Impact on a Solid Under Reduced Air Pressure

KAUST Repository

Li, Erqiang; Langley, Kenneth R.; Tian, Yuan Si; Hicks, Peter D.; Thoroddsen, Sigurdur T

2017-01-01

the compressibility parameter exceeds similar to 25. This bifurcation is also imprinted onto some of the impacts, as a double contact. In addition to the central air disc inside the first ring contact, this is immediately followed by a second ring contact, which

High-resolution of particle contacts via fluorophore exclusion in deep-imaging of jammed colloidal packings

Science.gov (United States)

Kyeyune-Nyombi, Eru; Morone, Flaviano; Liu, Wenwei; Li, Shuiqing; Gilchrist, M. Lane; Makse, Hernán A.

2018-01-01

Understanding the structural properties of random packings of jammed colloids requires an unprecedented high-resolution determination of the contact network providing mechanical stability to the packing. Here, we address the determination of the contact network by a novel strategy based on fluorophore signal exclusion of quantum dot nanoparticles from the contact points. We use fluorescence labeling schemes on particles inspired by biology and biointerface science in conjunction with fluorophore exclusion at the contact region. The method provides high-resolution contact network data that allows us to measure structural properties of the colloidal packing near marginal stability. We determine scaling laws of force distributions, soft modes, correlation functions, coordination number and free volume that define the universality class of jammed colloidal packings and can be compared with theoretical predictions. The contact detection method opens up further experimental testing at the interface of jamming and glass physics.

Concurrency-Induced Transitions in Epidemic Dynamics on Temporal Networks.

Science.gov (United States)

Onaga, Tomokatsu; Gleeson, James P; Masuda, Naoki

2017-09-08

Social contact networks underlying epidemic processes in humans and animals are highly dynamic. The spreading of infections on such temporal networks can differ dramatically from spreading on static networks. We theoretically investigate the effects of concurrency, the number of neighbors that a node has at a given time point, on the epidemic threshold in the stochastic susceptible-infected-susceptible dynamics on temporal network models. We show that network dynamics can suppress epidemics (i.e., yield a higher epidemic threshold) when the node's concurrency is low, but can also enhance epidemics when the concurrency is high. We analytically determine different phases of this concurrency-induced transition, and confirm our results with numerical simulations.

Concurrency-Induced Transitions in Epidemic Dynamics on Temporal Networks

Science.gov (United States)

Onaga, Tomokatsu; Gleeson, James P.; Masuda, Naoki

2017-09-01

Social contact networks underlying epidemic processes in humans and animals are highly dynamic. The spreading of infections on such temporal networks can differ dramatically from spreading on static networks. We theoretically investigate the effects of concurrency, the number of neighbors that a node has at a given time point, on the epidemic threshold in the stochastic susceptible-infected-susceptible dynamics on temporal network models. We show that network dynamics can suppress epidemics (i.e., yield a higher epidemic threshold) when the node's concurrency is low, but can also enhance epidemics when the concurrency is high. We analytically determine different phases of this concurrency-induced transition, and confirm our results with numerical simulations.

Analytic Treatment of Deep Neural Networks Under Additive Gaussian Noise

KAUST Repository

Alfadly, Modar

2018-01-01

Despite the impressive performance of deep neural networks (DNNs) on numerous vision tasks, they still exhibit yet-to-understand uncouth behaviours. One puzzling behaviour is the reaction of DNNs to various noise attacks, where it has been shown that there exist small adversarial noise that can result in a severe degradation in the performance of DNNs. To rigorously treat this, we derive exact analytic expressions for the first and second moments (mean and variance) of a small piecewise linear (PL) network with a single rectified linear unit (ReLU) layer subject to general Gaussian input. We experimentally show that these expressions are tight under simple linearizations of deeper PL-DNNs, especially popular architectures in the literature (e.g. LeNet and AlexNet). Extensive experiments on image classification show that these expressions can be used to study the behaviour of the output mean of the logits for each class, the inter-class confusion and the pixel-level spatial noise sensitivity of the network. Moreover, we show how these expressions can be used to systematically construct targeted and non-targeted adversarial attacks. Then, we proposed a special estimator DNN, named mixture of linearizations (MoL), and derived the analytic expressions for its output mean and variance, as well. We employed these expressions to train the model to be particularly robust against Gaussian attacks without the need for data augmentation. Upon training this network on a loss that is consolidated with the derived output probabilistic moments, the network is not only robust under very high variance Gaussian attacks but is also as robust as networks that are trained with 20 fold data augmentation.

Analytic Treatment of Deep Neural Networks Under Additive Gaussian Noise

KAUST Repository

Alfadly, Modar M.

2018-04-12

Despite the impressive performance of deep neural networks (DNNs) on numerous vision tasks, they still exhibit yet-to-understand uncouth behaviours. One puzzling behaviour is the reaction of DNNs to various noise attacks, where it has been shown that there exist small adversarial noise that can result in a severe degradation in the performance of DNNs. To rigorously treat this, we derive exact analytic expressions for the first and second moments (mean and variance) of a small piecewise linear (PL) network with a single rectified linear unit (ReLU) layer subject to general Gaussian input. We experimentally show that these expressions are tight under simple linearizations of deeper PL-DNNs, especially popular architectures in the literature (e.g. LeNet and AlexNet). Extensive experiments on image classification show that these expressions can be used to study the behaviour of the output mean of the logits for each class, the inter-class confusion and the pixel-level spatial noise sensitivity of the network. Moreover, we show how these expressions can be used to systematically construct targeted and non-targeted adversarial attacks. Then, we proposed a special estimator DNN, named mixture of linearizations (MoL), and derived the analytic expressions for its output mean and variance, as well. We employed these expressions to train the model to be particularly robust against Gaussian attacks without the need for data augmentation. Upon training this network on a loss that is consolidated with the derived output probabilistic moments, the network is not only robust under very high variance Gaussian attacks but is also as robust as networks that are trained with 20 fold data augmentation.

Occupational contact urticaria: lessons from the French National Network for Occupational Disease Vigilance and Prevention (RNV3P).

Science.gov (United States)

Bensefa-Colas, L; Telle-Lamberton, M; Faye, S; Bourrain, J-L; Crépy, M-N; Lasfargues, G; Choudat, D; Momas, I

2015-12-01

Occupational contact urticaria (OCU) is an occupational contact dermatitis that can cause serious health consequences and disability at work. To describe OCU and its temporal trends by the main causal agents and activity sectors in a nationwide scheme in France. Using data from the French National Network for Occupational Disease Vigilance and Prevention (RNV3P), we described OCU reported during the period 2001-10 and analysed the temporal trends of OCU and OCU attributed to the most frequent agents over the study period. Trends analyses were supported by reporting odds ratios using a logistic regression model with reference to 2001, or with time as a continuous variable. During the study period, 251 cases of OCU were reported in RNV3P, half of which were due to natural rubber latex, in particular in the health and social work activity sector (HSW). The number of these cases declined significantly over the study period (19% per year), and particularly after 2006. Conversely, the other causes of OCU did not decrease. Using surveillance data from a French national network, this study has found that there was a significant decline in OCU due to natural rubber latex, particularly in the HSW, when powdered latex gloves were banned from French hospitals. Our results show the effectiveness of this preventive measure, and suggest that this practice should be extended to other sectors. © 2015 British Association of Dermatologists.

Epidemic spreading in networks with nonrandom long-range interactions

Science.gov (United States)

Estrada, Ernesto; Kalala-Mutombo, Franck; Valverde-Colmeiro, Alba

2011-09-01

An “infection,” understood here in a very broad sense, can be propagated through the network of social contacts among individuals. These social contacts include both “close” contacts and “casual” encounters among individuals in transport, leisure, shopping, etc. Knowing the first through the study of the social networks is not a difficult task, but having a clear picture of the network of casual contacts is a very hard problem in a society of increasing mobility. Here we assume, on the basis of several pieces of empirical evidence, that the casual contacts between two individuals are a function of their social distance in the network of close contacts. Then, we assume that we know the network of close contacts and infer the casual encounters by means of nonrandom long-range (LR) interactions determined by the social proximity of the two individuals. This approach is then implemented in a susceptible-infected-susceptible (SIS) model accounting for the spread of infections in complex networks. A parameter called “conductance” controls the feasibility of those casual encounters. In a zero conductance network only contagion through close contacts is allowed. As the conductance increases the probability of having casual encounters also increases. We show here that as the conductance parameter increases, the rate of propagation increases dramatically and the infection is less likely to die out. This increment is particularly marked in networks with scale-free degree distributions, where infections easily become epidemics. Our model provides a general framework for studying epidemic spreading in networks with arbitrary topology with and without casual contacts accounted for by means of LR interactions.

Mixed Transportation Network Design under a Sustainable Development Perspective

Directory of Open Access Journals (Sweden)

Jin Qin

2013-01-01

Full Text Available A mixed transportation network design problem considering sustainable development was studied in this paper. Based on the discretization of continuous link-grade decision variables, a bilevel programming model was proposed to describe the problem, in which sustainability factors, including vehicle exhaust emissions, land-use scale, link load, and financial budget, are considered. The objective of the model is to minimize the total amount of resources exploited under the premise of meeting all the construction goals. A heuristic algorithm, which combined the simulated annealing and path-based gradient projection algorithm, was developed to solve the model. The numerical example shows that the transportation network optimized with the method above not only significantly alleviates the congestion on the link, but also reduces vehicle exhaust emissions within the network by up to 41.56%.

Mixed Transportation Network Design under a Sustainable Development Perspective

Science.gov (United States)

Qin, Jin; Ni, Ling-lin; Shi, Feng

2013-01-01

A mixed transportation network design problem considering sustainable development was studied in this paper. Based on the discretization of continuous link-grade decision variables, a bilevel programming model was proposed to describe the problem, in which sustainability factors, including vehicle exhaust emissions, land-use scale, link load, and financial budget, are considered. The objective of the model is to minimize the total amount of resources exploited under the premise of meeting all the construction goals. A heuristic algorithm, which combined the simulated annealing and path-based gradient projection algorithm, was developed to solve the model. The numerical example shows that the transportation network optimized with the method above not only significantly alleviates the congestion on the link, but also reduces vehicle exhaust emissions within the network by up to 41.56%. PMID:23476142

Trade networks evolution under the conditions of stock market globalization

Directory of Open Access Journals (Sweden)

Kopylova Olga Volodymyrivna

2016-12-01

Full Text Available The modern perception of the stock market in terms of information technologies rapid development and under the institutionalists influence has been significantly modified and becomes multifaceted. It was detected that the main function of the market is activated, information asymmetry is minimized and more advanced financial architecture space is formed through trade networks. Formation of the modern trade networks has started on the basis of the old infrastructure, that had the highest tendency to self-organization and adaptation. The proposed architecture of trade networks of the stock market has a very clear vector of subordination – from top to bottom and has a number of positive points.

Comparison of Contact Patterns Relevant for Transmission of Respiratory Pathogens in Thailand and the Netherlands Using Respondent-Driven Sampling

Science.gov (United States)

Stein, Mart L.; van Steenbergen, Jim E.; Buskens, Vincent; van der Heijden, Peter G. M.; Chanyasanha, Charnchudhi; Tipayamongkholgul, Mathuros; Thorson, Anna E.; Bengtsson, Linus; Lu, Xin; Kretzschmar, Mirjam E. E.

2014-01-01

Understanding infection dynamics of respiratory diseases requires the identification and quantification of behavioural, social and environmental factors that permit the transmission of these infections between humans. Little empirical information is available about contact patterns within real-world social networks, let alone on differences in these contact networks between populations that differ considerably on a socio-cultural level. Here we compared contact network data that were collected in the Netherlands and Thailand using a similar online respondent-driven method. By asking participants to recruit contact persons we studied network links relevant for the transmission of respiratory infections. We studied correlations between recruiter and recruited contacts to investigate mixing patterns in the observed social network components. In both countries, mixing patterns were assortative by demographic variables and random by total numbers of contacts. However, in Thailand participants reported overall more contacts which resulted in higher effective contact rates. Our findings provide new insights on numbers of contacts and mixing patterns in two different populations. These data could be used to improve parameterisation of mathematical models used to design control strategies. Although the spread of infections through populations depends on more factors, found similarities suggest that spread may be similar in the Netherlands and Thailand. PMID:25423343

Formal Models of the Network Co-occurrence Underlying Mental Operations.

Directory of Open Access Journals (Sweden)

Danilo Bzdok

2016-06-01

Full Text Available Systems neuroscience has identified a set of canonical large-scale networks in humans. These have predominantly been characterized by resting-state analyses of the task-unconstrained, mind-wandering brain. Their explicit relationship to defined task performance is largely unknown and remains challenging. The present work contributes a multivariate statistical learning approach that can extract the major brain networks and quantify their configuration during various psychological tasks. The method is validated in two extensive datasets (n = 500 and n = 81 by model-based generation of synthetic activity maps from recombination of shared network topographies. To study a use case, we formally revisited the poorly understood difference between neural activity underlying idling versus goal-directed behavior. We demonstrate that task-specific neural activity patterns can be explained by plausible combinations of resting-state networks. The possibility of decomposing a mental task into the relative contributions of major brain networks, the "network co-occurrence architecture" of a given task, opens an alternative access to the neural substrates of human cognition.

Two-dimensional plasmons in lateral carbon nanotube network structures and their effect on the terahertz radiation detection

International Nuclear Information System (INIS)

Ryzhii, V.; Otsuji, T.; Ryzhii, M.; Leiman, V. G.; Fedorov, G.; Goltzman, G. N.; Titova, N.; Gayduchenko, I. A.; Coquillat, D.; But, D.; Knap, W.; Mitin, V.; Shur, M. S.

2016-01-01

We consider the carrier transport and plasmonic phenomena in the lateral carbon nanotube (CNT) networks forming the device channel with asymmetric electrodes. One electrode is the Ohmic contact to the CNT network and the other contact is the Schottky contact. These structures can serve as detectors of the terahertz (THz) radiation. We develop the device model for collective response of the lateral CNT networks which comprise a mixture of randomly oriented semiconductor CNTs (s-CNTs) and quasi-metal CNTs (m-CNTs). The proposed model includes the concept of the collective two-dimensional (2D) plasmons in relatively dense networks of randomly oriented CNTs (CNT “felt”) and predicts the detector responsivity spectral characteristics exhibiting sharp resonant peaks at the signal frequencies corresponding to the 2D plasmonic resonances. The detection mechanism is the rectification of the ac current due the nonlinearity of the Schottky contact current-voltage characteristics under the conditions of a strong enhancement of the potential drop at this contact associated with the plasmon excitation. The detector responsivity depends on the fractions of the s- and m-CNTs. The burning of the near-contact regions of the m-CNTs or destruction of these CNTs leads to a marked increase in the responsivity in agreement with our experimental data. The resonant THz detectors with sufficiently dense lateral CNT networks can compete and surpass other THz detectors using plasmonic effects at room temperatures.

Two-dimensional plasmons in lateral carbon nanotube network structures and their effect on the terahertz radiation detection

Energy Technology Data Exchange (ETDEWEB)

Ryzhii, V. [Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Institute of Ultra High Frequency Semiconductor Electronics of RAS, Moscow 117105 (Russian Federation); Center for Photonics and Infrared Engineering, Bauman Moscow State Technical University, Moscow 111005 (Russian Federation); Otsuji, T. [Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Ryzhii, M. [Department of Computer Science and Engineering, University of Aizu, Aizu-Wakamatsu 965-8580 (Japan); Leiman, V. G. [Department of General Physics, Moscow Institute of Physics and Technology, Dolgoprudny, 147100 (Russian Federation); Fedorov, G. [Department of General Physics, Moscow Institute of Physics and Technology, Dolgoprudny, 147100 (Russian Federation); Physics Department, Moscow State Pedagogical University, Moscow 119991 (Russian Federation); Goltzman, G. N.; Titova, N. [Physics Department, Moscow State Pedagogical University, Moscow 119991 (Russian Federation); Gayduchenko, I. A. [Physics Department, Moscow State Pedagogical University, Moscow 119991 (Russian Federation); National Research Center “Kurchatov Institute,” Moscow 123182 (Russian Federation); Coquillat, D.; But, D.; Knap, W. [Laboratoire Charles Coulomb UMR 5221, Universite Montpellier 2 and CNRS, F-34095, Montpellier (France); Mitin, V. [Department of Electrical Engineering, University at Buffalo, Buffalo, New York 1460-1920 (United States); Shur, M. S. [Departments of Electrical, Computer, and Systems Engineering and Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

2016-07-28

We consider the carrier transport and plasmonic phenomena in the lateral carbon nanotube (CNT) networks forming the device channel with asymmetric electrodes. One electrode is the Ohmic contact to the CNT network and the other contact is the Schottky contact. These structures can serve as detectors of the terahertz (THz) radiation. We develop the device model for collective response of the lateral CNT networks which comprise a mixture of randomly oriented semiconductor CNTs (s-CNTs) and quasi-metal CNTs (m-CNTs). The proposed model includes the concept of the collective two-dimensional (2D) plasmons in relatively dense networks of randomly oriented CNTs (CNT “felt”) and predicts the detector responsivity spectral characteristics exhibiting sharp resonant peaks at the signal frequencies corresponding to the 2D plasmonic resonances. The detection mechanism is the rectification of the ac current due the nonlinearity of the Schottky contact current-voltage characteristics under the conditions of a strong enhancement of the potential drop at this contact associated with the plasmon excitation. The detector responsivity depends on the fractions of the s- and m-CNTs. The burning of the near-contact regions of the m-CNTs or destruction of these CNTs leads to a marked increase in the responsivity in agreement with our experimental data. The resonant THz detectors with sufficiently dense lateral CNT networks can compete and surpass other THz detectors using plasmonic effects at room temperatures.

an architecture-based technique to mobile contact recommendation

African Journals Online (AJOL)

user

Aside being able to store the name of contacts and their phone numbers, there are ... the artificial neural network technique [21], along with ... Recommendation is part of everyday life. This concept ... However, to use RSs some level of intelligence must be ...... [3] Min J.-K. & Cho S.-B.Mobile Human Network Management.

Robustness of Dengue Complex Network under Targeted versus Random Attack

Directory of Open Access Journals (Sweden)

Hafiz Abid Mahmood Malik

2017-01-01

Full Text Available Dengue virus infection is one of those epidemic diseases that require much consideration in order to save the humankind from its unsafe impacts. According to the World Health Organization (WHO, 3.6 billion individuals are at risk because of the dengue virus sickness. Researchers are striving to comprehend the dengue threat. This study is a little commitment to those endeavors. To observe the robustness of the dengue network, we uprooted the links between nodes randomly and targeted by utilizing different centrality measures. The outcomes demonstrated that 5% targeted attack is equivalent to the result of 65% random assault, which showed the topology of this complex network validated a scale-free network instead of random network. Four centrality measures (Degree, Closeness, Betweenness, and Eigenvector have been ascertained to look for focal hubs. It has been observed through the results in this study that robustness of a node and links depends on topology of the network. The dengue epidemic network presented robust behaviour under random attack, and this network turned out to be more vulnerable when the hubs of higher degree have higher probability to fail. Moreover, representation of this network has been projected, and hub removal impact has been shown on the real map of Gombak (Malaysia.

Solar Cels With Reduced Contact Areas

Science.gov (United States)

Daud, T.; Crotty, G. T.; Kachare, A. H.; Lewis, J. T.

1987-01-01

Efficiency of silicon solar cells increased about 20 percent using smaller metal-contact area on silicon at front and back of each cell. Reduction in contact area reduces surface recombination velocity under contact and thus reduces reverse saturation current and increases opencircuit voltage..

Colors and contact dermatitis.

Science.gov (United States)

Bonamonte, Domenico; Foti, Caterina; Romita, Paolo; Vestita, Michelangelo; Angelini, Gianni

2014-01-01

The diagnosis of skin diseases relies on several clinical signs, among which color is of paramount importance. In this review, we consider certain clinical presentations of both eczematous and noneczematous contact dermatitis in which color plays a peculiar role orientating toward the right diagnosis. The conditions that will be discussed include specific clinical-morphologic subtypes of eczematous contact dermatitis, primary melanocytic, and nonmelanocytic contact hyperchromia, black dermographism, contact chemical leukoderma, and others. Based on the physical, chemical, and biologic factors underlying a healthy skin color, the various skin shades drawing a disease picture are thoroughly debated, stressing their etiopathogenic origins and histopathologic aspects.

Optimal Intermittent Operation of Water Distribution Networks under Water Shortage

Directory of Open Access Journals (Sweden)

mohamad Solgi

2017-07-01

Full Text Available Under water shortage conditions, it is necessary to exercise water consumption management practices in water distribution networks (WDN. Intermittent supply of water is one such practice that makes it possible to supply consumption nodal demands with the required pressure via water cutoff to some consumers during certain hours of the day. One of the most important issues that must be observed in this management practice is the equitable and uniform water distribution among the consumers. In the present study, uniformity in water distribution and minimum supply of water to all consumers are defined as justice and equity, respectively. Also, an optimization model has been developed to find an optimal intermittent supply schedule that ensures maximum number of demand nodes are supplied with water while the constraints on the operation of water distribution networks are also observed. To show the efficiency of the proposed model, it has been used in the Two-Loop distribution network under several different scenarios of water shortage. The optimization model has been solved using the honey bee mating optimization algorithm (HBMO linked to the hydraulic simulator EPANET. The results obtained confirm the efficiency of the proposed model in achieving an optimal intermittent supply schedule. Moreover, the model is found capable of distributing the available water in an equitable and just manner among all the consumers even under severe water shoratges.

Stability of selected volatile contact allergens in different patch test chambers under different storage conditions

DEFF Research Database (Denmark)

Mose, Kristian Fredløv; Andersen, Klaus Ejner; Christensen, Lars Porskjaer

2012-01-01

Background. Patch test preparations of volatile substances may evaporate during storage, thereby giving rise to reduced patch test concentrations. Objectives. To investigate the stability of selected acrylates/methacrylates and fragrance allergens in three different test chambers under different...... both storage conditions, whereas MMA and 2-HPA required cool storage for maintenance of the limit. Conclusion. The Van der Bend® transport container was the best device for storage of samples of volatile contact allergens....

Mechanical Contact Experiments and Simulations

DEFF Research Database (Denmark)

Nielsen, Chris Valentin; Martins, P; Zhang, W.

2011-01-01

Mechanical contact is studied under dynamic development by means of a combined numerical and experimental investigation. The experiments are designed to allow dynamical development of non-planar contact areas with significant expansion in all three directions as the load is increased. Different....... The overall investigation serves for testing and validating the numerical implementation of the mechanical contact, which is one of the main contributions to a system intended for 3D simulation of resistance welding. Correct modelling of contact between parts to be welded, as well as contact with electrodes......, is crucial for satisfactory modelling of the resistance welding process. The resistance heating at the contact interfaces depends on both contact area and pressure, and as the contact areas develop dynamically, the presented tests are relevant for assessing the validity and accuracy of the mechanical contact...

Convergence and approximate calculation of average degree under different network sizes for decreasing random birth-and-death networks

Science.gov (United States)

Long, Yin; Zhang, Xiao-Jun; Wang, Kui

2018-05-01

In this paper, convergence and approximate calculation of average degree under different network sizes for decreasing random birth-and-death networks (RBDNs) are studied. First, we find and demonstrate that the average degree is convergent in the form of power law. Meanwhile, we discover that the ratios of the back items to front items of convergent reminder are independent of network link number for large network size, and we theoretically prove that the limit of the ratio is a constant. Moreover, since it is difficult to calculate the analytical solution of the average degree for large network sizes, we adopt numerical method to obtain approximate expression of the average degree to approximate its analytical solution. Finally, simulations are presented to verify our theoretical results.

Analysis of core-periphery organization in protein contact networks reveals groups of structurally and functionally critical residues.

Science.gov (United States)

Isaac, Arnold Emerson; Sinha, Sitabhra

2015-10-01

The representation of proteins as networks of interacting amino acids, referred to as protein contact networks (PCN), and their subsequent analyses using graph theoretic tools, can provide novel insights into the key functional roles of specific groups of residues. We have characterized the networks corresponding to the native states of 66 proteins (belonging to different families) in terms of their core-periphery organization. The resulting hierarchical classification of the amino acid constituents of a protein arranges the residues into successive layers - having higher core order - with increasing connection density, ranging from a sparsely linked periphery to a densely intra-connected core (distinct from the earlier concept of protein core defined in terms of the three-dimensional geometry of the native state, which has least solvent accessibility). Our results show that residues in the inner cores are more conserved than those at the periphery. Underlining the functional importance of the network core, we see that the receptor sites for known ligand molecules of most proteins occur in the innermost core. Furthermore, the association of residues with structural pockets and cavities in binding or active sites increases with the core order. From mutation sensitivity analysis, we show that the probability of deleterious or intolerant mutations also increases with the core order. We also show that stabilization centre residues are in the innermost cores, suggesting that the network core is critically important in maintaining the structural stability of the protein. A publicly available Web resource for performing core-periphery analysis of any protein whose native state is known has been made available by us at http://www.imsc.res.in/ ~sitabhra/proteinKcore/index.html.

Effect of surfaces similarity on contact resistance of fractal rough surfaces under cyclic loading

Science.gov (United States)

Gao, Yuanwen; Liu, Limei; Ta, Wurui; Song, Jihua

2018-03-01

Although numerous studies have shown that contact resistance depends significantly on roughness and fractal dimension, it remains elusive how they affect contact resistance between rough surfaces. The interface similarity index is first proposed to describe the similarity of the contact surfaces, which gives a good indication of the actual contact area between surfaces. We reveal that the surfaces' similarity be an origin of contact resistance variation. The cyclic loading can increase the contact stiffness, and the contact stiffness increases with the increase of the interface similarity index. These findings explain the mechanism of surface roughness and fractal dimension on contact resistance, and also provide reference for the reliability design of the electrical connection.

Similarity between community structures of different online social networks and its impact on underlying community detection

Science.gov (United States)

Fan, W.; Yeung, K. H.

2015-03-01

As social networking services are popular, many people may register in more than one online social network. In this paper we study a set of users who have accounts of three online social networks: namely Foursquare, Facebook and Twitter. Community structure of this set of users may be reflected in these three online social networks. Therefore, high correlation between these reflections and the underlying community structure may be observed. In this work, community structures are detected in all three online social networks. Also, we investigate the similarity level of community structures across different networks. It is found that they show strong correlation with each other. The similarity between different networks may be helpful to find a community structure close to the underlying one. To verify this, we propose a method to increase the weights of some connections in networks. With this method, new networks are generated to assist community detection. By doing this, value of modularity can be improved and the new community structure match network's natural structure better. In this paper we also show that the detected community structures of online social networks are correlated with users' locations which are identified on Foursquare. This information may also be useful for underlying community detection.

Patch test results with fragrance markers of the baseline series - analysis of the European Surveillance System on Contact Allergies (ESSCA) network 2009-2012

DEFF Research Database (Denmark)

Frosch, Peter J; Duus Johansen, Jeanne; Schuttelaar, Marie-Louise A

2015-01-01

BACKGROUND: Contact allergy to fragrances is common, and impairs quality of life, particularly in young women. OBJECTIVE: To provide current results on the prevalences of sensitization to fragrance allergens used as markers in the baseline series of most European countries. METHODS: Data of patie......BACKGROUND: Contact allergy to fragrances is common, and impairs quality of life, particularly in young women. OBJECTIVE: To provide current results on the prevalences of sensitization to fragrance allergens used as markers in the baseline series of most European countries. METHODS: Data...... of patients consecutively patch tested between 2009 and 2012 in 12 European countries with fragrance allergens contained in the baseline series were collected by the European Surveillance System on Contact Allergies network and descriptively analysed. Four departments used the TRUE Test(®) system. RESULTS......: Contact allergy to fragrances is common throughout Europe, with regional variation probably being explained by patch test technique, and differences in exposure and referral patterns. The current basic markers of fragrance sensitivity in the baseline series should be supplemented with additional fragrance...

Design, simulation and fabrication of a novel contact-enhanced MEMS inertial switch with a movable contact point

International Nuclear Information System (INIS)

Cai Haogang; Ding Guifu; Yang Zhuoqing; Su Zhijuan; Zhou Jiansheng; Wang Hong

2008-01-01

A novel inertial switch based on a micro-electro-mechanical system (MEMS) was designed, which consists of three main parts: a proof mass as the movable electrode, a cross beam as the stationary electrode and a movable contact point to prolong the contact time. A MATLAB/Simulink model, which had been verified by comparison with ANSYS transient simulation, was built to simulate the dynamic response, based on which the contact-enhancing mechanism was confirmed and the dependence of threshold acceleration on the proof mass thickness was studied. The simulated dynamic responses under various accelerations exhibit satisfactory device behaviors: the switch-on time is prolonged under transient acceleration; the switch-on state is more continuous than the conventional design under long lasting acceleration. The inertial micro-switch was fabricated by multilayer electroplating technology and then tested by a drop hammer experiment. The test results indicate that the contact effect was improved significantly and a steady switch-on time of over 50 µs was observed under half-sine wave acceleration with 1 ms duration, in agreement with the dynamic simulation

25G compared with 20G vitrectomy under Resight non-contact wide-angle lenses for Terson syndrome.

Science.gov (United States)

Mao, Xinbang; You, Zhipeng

2017-08-01

The aim of the present study was to compare the effectiveness of 25G vitrectomy to standard 20G vitrectomy for treatment of Terson syndrome under Resight non-contact wide-angle lenses. This was a case-control study of 20 patients with Terson syndrome (study group) that underwent 25G vitrectomy under Resight non-contact wide-angle lenses, with those of 20 matched patients that underwent 20G vitrectomy (control group). Medical records were reviewed from between July 2011 and October 2013. Data included results of the Early Treatment Diabetic Retinopathy Study examination, ophthalmology B-scan ultrasonography and fundus photography. The mean age, follow-up time, the preoperative visual acuity of LogMAR and the preoperative intraocular pressure (IOP) were all comparable in the two groups (all P>0.05). There were statistically significant differences in postoperative visual acuity of LogMAR compared with preoperative visual acuity (Pcontact wide-angle lenses can achieve a significantly shorter operative time and lower post-operative IOP compared with 20G Vitrectomy.

PyContact: Rapid, Customizable, and Visual Analysis of Noncovalent Interactions in MD Simulations.

Science.gov (United States)

Scheurer, Maximilian; Rodenkirch, Peter; Siggel, Marc; Bernardi, Rafael C; Schulten, Klaus; Tajkhorshid, Emad; Rudack, Till

2018-02-06

Molecular dynamics (MD) simulations have become ubiquitous in all areas of life sciences. The size and model complexity of MD simulations are rapidly growing along with increasing computing power and improved algorithms. This growth has led to the production of a large amount of simulation data that need to be filtered for relevant information to address specific biomedical and biochemical questions. One of the most relevant molecular properties that can be investigated by all-atom MD simulations is the time-dependent evolution of the complex noncovalent interaction networks governing such fundamental aspects as molecular recognition, binding strength, and mechanical and structural stability. Extracting, evaluating, and visualizing noncovalent interactions is a key task in the daily work of structural biologists. We have developed PyContact, an easy-to-use, highly flexible, and intuitive graphical user interface-based application, designed to provide a toolkit to investigate biomolecular interactions in MD trajectories. PyContact is designed to facilitate this task by enabling identification of relevant noncovalent interactions in a comprehensible manner. The implementation of PyContact as a standalone application enables rapid analysis and data visualization without any additional programming requirements, and also preserves full in-program customization and extension capabilities for advanced users. The statistical analysis representation is interactively combined with full mapping of the results on the molecular system through the synergistic connection between PyContact and VMD. We showcase the capabilities and scientific significance of PyContact by analyzing and visualizing in great detail the noncovalent interactions underlying the ion permeation pathway of the human P2X 3 receptor. As a second application, we examine the protein-protein interaction network of the mechanically ultrastable cohesin-dockering complex. Copyright © 2017 Biophysical Society

An absorptive single-pole four-throw switch using multiple-contact MEMS switches and its application to a monolithic millimeter-wave beam-forming network

International Nuclear Information System (INIS)

Lee, Sanghyo; Kim, Jong-Man; Kim, Yong-Kweon; Kwon, Youngwoo

2009-01-01

In this paper, a new absorptive single-pole four-throw (SP4T) switch based on multiple-contact switching is proposed and integrated with a Butler matrix to demonstrate a monolithic beam-forming network at millimeter waves (mm waves). In order to simplify the switching driving circuit and reduce the number of unit switches in an absorptive SP4T switch, the individual switches were replaced with long-span multiple-contact switches using stress-free single-crystalline-silicon MEMS technology. This approach improves the mechanical stability as well as the manufacturing yield, thereby allowing successful integration into a monolithic beam former. The fabricated absorptive SP4T MEMS switch shows insertion loss less than 1.3 dB, return losses better than 11 dB at 30 GHz and wideband isolation performance higher than 39 dB from 20 to 40 GHz. The absorptive SP4T MEMS switch is integrated with a 4 × 4 Butler matrix on a single chip to implement a monolithic beam-forming network, directing beam into four distinct angles. Array factors from the measured data show that the proposed absorptive SPnT MEMS switch can be effectively used for high-performance mm-wave beam-switching systems. This work corresponds to the first demonstration of a monolithic beam-forming network using switched beams

Modern contact investigation methods for enhancing tuberculosis control in Aboriginal communities

Directory of Open Access Journals (Sweden)

Victoria J. Cook

2012-05-01

Full Text Available The Aboriginal communities in Canada are challenged by a disproportionate burden of TB infection and disease. Contact investigation (CI guidelines exist but these strategies do not take into account the unique social structure of different populations. Because of the limitations of traditional CI, new approaches are under investigation and include the use of social network analysis, geographic information systems and genomics, in addition to the widespread use of genotyping to better understand TB transmission. Guidelines for the routine use of network methods and other novel methodologies for TB CI and outbreak investigation do not exist despite the gathering evidence that these approaches can positively impact TB control efforts, even in Aboriginal communities. The feasibility and efficacy of these novel approaches to CI in Aboriginal communities requires further investigation. The successful integration of these novel methodologies will require community involvement, capacity building and ongoing support at every level. The outcome will not only be the systematic collection, analysis, and interpretation of CI data in high-burden communities to assess transmission but the prioritization of contacts who are candidates for treatment of LTBI which will break the cycle of transmission. Ultimately, the measure of success will be a clear and sustained decline in TB incidence in Aboriginal communities.

Developmental Dynamics of Intergroup Contact and Intergroup Attitudes: Long-Term Effects in Adolescence and Early Adulthood

NARCIS (Netherlands)

Wölfer, R.; van Zalk, M.H.W.; Schmid, K.; Hewstone, M.

2016-01-01

Intergroup contact represents a powerful way to improve intergroup attitudes and to overcome prejudice and discrimination. However, long-term effects of intergroup contact that consider social network dynamics have rarely been studied at a young age. Study 1 validated an optimized social network

Potential for transmission of infections in networks of cattle farms

Directory of Open Access Journals (Sweden)

V.V. Volkova

2010-09-01

Full Text Available The aim of this analysis is to evaluate how generic properties of networks of livestock farms connected by movements of cattle impact on the potential for spread of infectious diseases. We focus on endemic diseases with long infectious periods in affected cattle, such as bovine tuberculosis. Livestock farm networks provide a rare example of large but fully specified directed contact networks, allowing investigations into how properties of such networks impact the potential for spread of infections within them. Here we quantify the latter in terms of the basic reproduction number, R0, and partition the contributions to R0 from first order moments (mean contact rates and second order moments (variances and covariances of contact rates of the farm contact matrices. We find that the second order properties make a substantial contribution to the magnitude of R0, similarly to that reported for other populations. Importantly, however, we find that the magnitude of these effects depends on exactly how the contacts between farms are defined or weighted. We note that the second order properties of a directed contact network may vary through time even with little change in the mean contact rates or in overall connectedness of the network. Keywords: Basic reproduction number, Infectious disease, Heterogeneity, 20–80 rule, Contact network, Bovine tuberculosis

Will electrical cyber-physical interdependent networks undergo first-order transition under random attacks?

Science.gov (United States)

Ji, Xingpei; Wang, Bo; Liu, Dichen; Dong, Zhaoyang; Chen, Guo; Zhu, Zhenshan; Zhu, Xuedong; Wang, Xunting

2016-10-01

Whether the realistic electrical cyber-physical interdependent networks will undergo first-order transition under random failures still remains a question. To reflect the reality of Chinese electrical cyber-physical system, the "partial one-to-one correspondence" interdependent networks model is proposed and the connectivity vulnerabilities of three realistic electrical cyber-physical interdependent networks are analyzed. The simulation results show that due to the service demands of power system the topologies of power grid and its cyber network are highly inter-similar which can effectively avoid the first-order transition. By comparing the vulnerability curves between electrical cyber-physical interdependent networks and its single-layer network, we find that complex network theory is still useful in the vulnerability analysis of electrical cyber-physical interdependent networks.

Transfer characteristics and contact resistance in Ni- and Ti-contacted graphene-based field-effect transistors

International Nuclear Information System (INIS)

Di Bartolomeo, A; Giubileo, F; Iemmo, L; Romeo, F; Santandrea, S; Gambardella, U

2013-01-01

We produced graphene-based field-effect transistors by contacting mono- and bi-layer graphene by sputtering Ni or Ti as metal electrodes. We performed electrical characterization of the devices by measuring their transfer and output characteristics. We clearly observed the presence of a double-dip feature in the conductance curve for Ni-contacted transistors, and we explain it in terms of charge transfer and graphene doping under the metal contacts. We also studied the contact resistance between the graphene and the metal electrodes with larger values of ∼30 kΩμm 2 recorded for Ti contacts. Importantly, we prove that the contact resistance is modulated by the back-gate voltage. (paper)

Contact-impact algorithms on parallel computers

International Nuclear Information System (INIS)

Zhong Zhihua; Nilsson, Larsgunnar

1994-01-01

Contact-impact algorithms on parallel computers are discussed within the context of explicit finite element analysis. The algorithms concerned include a contact searching algorithm and an algorithm for contact force calculations. The contact searching algorithm is based on the territory concept of the general HITA algorithm. However, no distinction is made between different contact bodies, or between different contact surfaces. All contact segments from contact boundaries are taken as a single set. Hierarchy territories and contact territories are expanded. A three-dimensional bucket sort algorithm is used to sort contact nodes. The defence node algorithm is used in the calculation of contact forces. Both the contact searching algorithm and the defence node algorithm are implemented on the connection machine CM-200. The performance of the algorithms is examined under different circumstances, and numerical results are presented. ((orig.))

2D simulation and performance evaluation of bifacial rear local contact c-Si solar cells under variable illumination conditions

KAUST Repository

Katsaounis, Theodoros; Kotsovos, Konstantinos; Gereige, Issam; Al-Saggaf, Ahmed; Tzavaras, Athanasios

2017-01-01

A customized 2D computational tool has been developed to simulate bifacial rear local contact PERC type PV structures based on the numerical solution of the transport equations through the finite element method. Simulations were performed under various device material parameters and back contact geometry configurations in order to optimize bifacial solar cell performance under different simulated illumination conditions. Bifacial device maximum power output was also compared with the monofacial equivalent one and the industrial standard Al-BSF structure. The performance of the bifacial structure during highly diffused irradiance conditions commonly observed in the Middle East region due to high concentrations of airborne dust particles was also investigated. Simulation results demonstrated that such conditions are highly favorable for the bifacial device because of the significantly increased diffuse component of the solar radiation which enters the back cell surface.

2D simulation and performance evaluation of bifacial rear local contact c-Si solar cells under variable illumination conditions

KAUST Repository

Katsaounis, Theodoros

2017-09-18

A customized 2D computational tool has been developed to simulate bifacial rear local contact PERC type PV structures based on the numerical solution of the transport equations through the finite element method. Simulations were performed under various device material parameters and back contact geometry configurations in order to optimize bifacial solar cell performance under different simulated illumination conditions. Bifacial device maximum power output was also compared with the monofacial equivalent one and the industrial standard Al-BSF structure. The performance of the bifacial structure during highly diffused irradiance conditions commonly observed in the Middle East region due to high concentrations of airborne dust particles was also investigated. Simulation results demonstrated that such conditions are highly favorable for the bifacial device because of the significantly increased diffuse component of the solar radiation which enters the back cell surface.

Nepal Networking

DEFF Research Database (Denmark)

Hansen, Annette Skovsted

, as a Danida fellow. Today, the older sister works in Nepal and the younger in Seattle, where they still make use of their personal networks including connections to their fellow alumni of technical assistance courses. Inspired by work on social remittances in combination with network theory , I argue......Technical Assistance courses have many functions apart from disseminating knowledge and information, one such function is to engender networks. During the course period, participants meet and establish contact and some of these contacts remain connections between alumni for many years after...... the courses are finished. The alumni networks depend on the uses they are put to by the individual alumni and the support they get from alumni and host countries. The United Nations initiated technical assistance courses in the late 1940s in order to train nationals from developing countries as a means...

Contact lines are unstable even under non-splashing droplets

Science.gov (United States)

Pack, Min; Kaneelil, Paul; Sun, Ying

2017-11-01

Drop impact is fundamental to natural and industrial processes such as rain-induced soil erosion and spray coating technologies. In this study, we elucidate the interfacial instabilities formed by air entrainment at the wetting front of impacting droplets on atomically smooth, viscous silicone oil films of constant thickness with varying droplet velocity, viscosity, surface tension, and ambient pressures. A high-speed total internal reflection microscopy technique accounting for the Fresnel relations at the droplet interface allowed for in-situ measurements of an entrained air rim at the wetting front. The growth of the air rim is a prerequisite to the instability which is formed when the gas pressure balances the capillary pressure near the wetting front. A critical capillary number, which inversely scales as the ambient pressure, is predicted and the result agrees well with the experiments. The wavenumber in the instability is shown to increase with viscosity and velocity but decrease with surface tension of the impacting drop. We thus conclude that the instability mechanism is in qualitative agreement with the Saffman-Taylor instability - where the low viscosity air is displacing the higher viscosity droplet. The low We contact line instabilities observed in this study provide a paradigm shift in the conventional understanding of hydrodynamic instabilities under drop impact which usually require We >>10.

Network Performance Improvement under Epidemic Failures in Optical Transport Networks

DEFF Research Database (Denmark)

Fagertun, Anna Manolova; Ruepp, Sarah Renée

2013-01-01

In this paper we investigate epidemic failure spreading in large- scale GMPLS-controlled transport networks. By evaluating the effect of the epidemic failure spreading on the network, we design several strategies for cost-effective network performance improvement via differentiated repair times....... First we identify the most vulnerable and the most strategic nodes in the network. Then, via extensive simulations we show that strategic placement of resources for improved failure recovery has better performance than randomly assigning lower repair times among the network nodes. Our OPNET simulation...... model can be used during the network planning process for facilitating cost- effective network survivability design....

Relationship between the real contact area and contact force in pre-sliding regime

International Nuclear Information System (INIS)

Song Baojiang; Yan Shaoze

2017-01-01

The pre-sliding regime is typically neglected in the dynamic modelling of mechanical systems. However, the change in contact state caused by static friction may decrease positional accuracy and control precision. To investigate the relationship between contact status and contact force in pre-sliding friction, an optical experimental method is presented in this paper. With this method, the real contact state at the interface of a transparent material can be observed based on the total reflection principle of light by using an image processing technique. A novel setup, which includes a pair of rectangular trapezoidal blocks, is proposed to solve the challenging issue of accurately applying different tangential and normal forces to the contact interface. The improved Otsu’s method is used for measurement. Through an experimental study performed on polymethyl methacrylate (PMMA), the quantity of contact asperities is proven to be the dominant factor that affects the real contact area. The relationship between the real contact area and the contact force in the pre-sliding regime is studied, and the distribution of static friction at the contact interface is qualitatively discussed. New phenomena in which the real contact area expands along with increasing static friction are identified. The aforementioned relationship is approximately linear at the contact interface under a constant normal pressure, and the distribution of friction stress decreases from the leading edge to the trailing edge. (paper)

Outbreak of contact sensitization to methylisothiazolinone: an analysis of French data from the REVIDAL-GERDA network.

Science.gov (United States)

Hosteing, Stéphanie; Meyer, Nicolas; Waton, Julie; Barbaud, Annick; Bourrain, Jean-Luc; Raison-Peyron, Nadia; Felix, Brigitte; Milpied-Homsi, Brigitte; Ferrier Le Bouedec, Marie-Christine; Castelain, Michel; Vital-Durand, Dominique; Debons, Michèle; Collet, Evelyne; Avenel-Audran, Martine; Mathelier-Fusade, Pascale; Vermeulen, Christophe; Assier, Haudrey; Gener, Gwendoline; Lartigau-Sezary, Isabelle; Catelain-Lamy, Amandine; Giordano-Labadie, Françoise

2014-05-01

The preservative methylisothiazolinone (MI) is used in combination with methylchloroisothiazolinone (MCI), but the MCI/MI mixture has been identified as highly allergenic. MI is considered to be less allergenic, and since the mid-2000s has been widely used alone, but is now clearly identified as a contact allergen. The French Vigilance Network for Dermatology and Allergy of the Study and Research Group on Contact Dermatitis (REVIDAL-GERDA) added MI to its baseline patch testing series in 2010. To evaluate the change in the proportion of MI-positive tests in France between 2010 and 2012. We conducted a nationwide, multicentre, retrospective study of all MI-tested patients between 2010 and 2012. Sixteen centres participated in the study (7874 patients were tested). Patch tests were performed mainly at a concentration of MI 200 ppm aq. We observed a significant increase in the proportion of MI-positive tests in 2012 and 2011 as compared with 2010 (5.6%, 3.3%, and 1.5%, respectively; p < 0.001). We report a significant increase in the number of MI-positive tests. MI is confirmed to be a rapidly emerging allergen, as also observed in other European countries. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Switching performance of OBS network model under prefetched real traffic

Science.gov (United States)

Huang, Zhenhua; Xu, Du; Lei, Wen

2005-11-01

Optical Burst Switching (OBS) [1] is now widely considered as an efficient switching technique in building the next generation optical Internet .So it's very important to precisely evaluate the performance of the OBS network model. The performance of the OBS network model is variable in different condition, but the most important thing is that how it works under real traffic load. In the traditional simulation models, uniform traffics are usually generated by simulation software to imitate the data source of the edge node in the OBS network model, and through which the performance of the OBS network is evaluated. Unfortunately, without being simulated by real traffic, the traditional simulation models have several problems and their results are doubtable. To deal with this problem, we present a new simulation model for analysis and performance evaluation of the OBS network, which uses prefetched IP traffic to be data source of the OBS network model. The prefetched IP traffic can be considered as real IP source of the OBS edge node and the OBS network model has the same clock rate with a real OBS system. So it's easy to conclude that this model is closer to the real OBS system than the traditional ones. The simulation results also indicate that this model is more accurate to evaluate the performance of the OBS network system and the results of this model are closer to the actual situation.

Evolution of cooperation under social pressure in multiplex networks.

Science.gov (United States)

Pereda, María

2016-09-01

In this work, we aim to contribute to the understanding of human prosocial behavior by studying the influence that a particular form of social pressure, "being watched," has on the evolution of cooperative behavior. We study how cooperation emerges in multiplex complex topologies by analyzing a particular bidirectionally coupled dynamics on top of a two-layer multiplex network (duplex). The coupled dynamics appears between the prisoner's dilemma game in a network and a threshold cascade model in the other. The threshold model is intended to abstract the behavior of a network of vigilant nodes that impose the pressure of being observed altering hence the temptation to defect of the dilemma. Cooperation or defection in the game also affects the state of a node of being vigilant. We analyze these processes on different duplex networks structures and assess the influence of the topology, average degree and correlated multiplexity, on the outcome of cooperation. Interestingly, we find that the social pressure of vigilance may impact cooperation positively or negatively, depending on the duplex structure, specifically the degree correlations between layers is determinant. Our results give further quantitative insights in the promotion of cooperation under social pressure.

Social network sites: Indispensable or optional social tools?

DEFF Research Database (Denmark)

Shklovski, Irina

2012-01-01

Much research has enumerated potential benefits of online social network sites. Given the pervasiveness of these sites and the numbers of people that use them daily, both re-search and media tend to make the assumption that social network sites have become indispensible to their users. Based...... on the analysis of qualitative data from users of social network sites in Russia and Kazakhstan, this paper consid-ers under what conditions social network sites can become indispensable to their users and when these technologies remain on the periphery of life despite fulfilling useful func-tions. For some...... respondents, these sites had become indis-pensable tools as they were integrated into everyday rou-tines of communicating with emotionally important and proximal contacts and were often used for coordination of offline activities. For others social network sites remained spaces where they occasionally visited...

Prediction of serviceability of the material working under conditions of dynamic contact with liquid medium

International Nuclear Information System (INIS)

Veksler, Yu.G.; Poluyanov, V.B.

1977-01-01

A method is suggested for selecting materials working in contact with fusible liquid metals under namic loading. It is recommended to determine the rate of failure in short-time tests of materials which have shown good corrosion resistence. A material thus selected is subject to short-time cavitation mechanical strength test and a creep test. After that the cavitation-mechanical strength is to be calculated with an account for variation of transverse cross-section area. An equation of cavitation failure rate vs. time is given

Intergranular Pressure Solution in Nacl: Grain-To-Grain Contact Experiments under the Optical Microscope Dissolution sous contrainte dans NaCl : expériences de contact grain à grain sous microscope optique

Directory of Open Access Journals (Sweden)

Spiers C. J.

2006-12-01

Full Text Available Intergranular Pressure Solution (IPS is an important geologic lithification, compaction and deformation mechanism in a wide variety of crustal rocks. Experimental studies of IPS in quartz aggregates have not been very successful due to the low rate of IPS, and IPS experiments performed using wet halite as a rock analogue (Spiers and Schutjens, 1990; Hickman and Evans, 1991 have left uncertainty about the detailed IPS mechanism and grain contact structure/wetting in this material. The present study reports four contact dissolution experiments performed under the optical microscope to study the mechanism and kinetics of IPS at single halite/halite and halite/glass contacts loaded under brine (room temperature. Normal constant contact forces in the range 1. 0 to 2. 6 N were applied in the presence of NaCl-saturated brine, exerting stresses of 0. 8 to 7. 4 MPa. Time-dependent mass removal and convergence were observed at all contacts. In all cases, loading of the contact (or increasing the load on the contact led to instantaneous formation of a rough contact morphology, composed of a crystallographically-controlled pattern of islands and channels with a length scale of several micrometers. This nonequilibrium microstructure evolved with time to an optically flat contact face while contact broadening and convergence continued. The smoothing/convergence process must therefore have involved diffusion of mass out of the contact, and expulsion of brine, through a connected brine phase within the contact. Whether a fine-scale rough structure persisted in contacts which evolved to optical flatness is not known, though post-test SEM (Scanning Electron Microscopy observations suggest that it may have. If so, its amplitude was less than 500 nm. Measurements of dissolution rates enabled comparison with a model for IPS. The analysis suggests that solute diffusion through the contact boundary was probably rate-controlling, with the contact structure and

Uranium mining and metallurgy library information service under the network environment

International Nuclear Information System (INIS)

Tang Lilei

2012-01-01

This paper analyzes the effect of the network environment on the uranium mining and metallurgy of the information service. Introduces some measures such as strengthening professional characteristic literature resources construction, changing the service mode, building up information navigation, deepening service, meet the individual needs of users, raising librarian's quality, promoting the co-construction and sharing of library information resources, and puts forward the development idea of uranium mining and metallurgy library information service under the network environment. (author)

Security Evaluation of the Cyber Networks under Advanced Persistent Threats

NARCIS (Netherlands)

Yang, L.; Li, Pengdeng; Yang, Xiaofan; Tang, Yuan Yan

2017-01-01

Advanced persistent threats (APTs) pose a grave threat to cyberspace, because they deactivate all the conventional cyber defense mechanisms. This paper addresses the issue of evaluating the security of the cyber networks under APTs. For this purpose, a dynamic model capturing the APT-based

Familiarity breeds contempt: combining proximity loggers and GPS reveals female white-tailed deer (Odocoileus virginianus) avoiding close contact with neighbors.

Science.gov (United States)

Tosa, Marie I; Schauber, Eric M; Nielsen, Clayton K

2015-01-01

Social interactions can influence infectious disease dynamics, particularly for directly transmitted pathogens. Therefore, reliable information on contact frequency within and among groups can better inform disease modeling and management. We compared three methods of assessing contact patterns: (1) space-use overlap (volume of interaction [VI]), (2) direct contact rates measured by simultaneous global positioning system (GPS) locations (<10 m apart), and (3) direct contact rates measured by proximity loggers (PLs; 1-m detection) among female white-tailed deer (Odocoileus virginianus). We calculated the PL∶GPS contact ratios to see whether both devices reveal similar contact patterns and thus predict similar pathogen transmission patterns. Contact rates measured by GPS and PLs were similarly high for two within-group dyads (pairs of deer in the same social groups). Dyads representing separate but neighboring groups (high VI) had PL∶GPS contact ratios near zero, whereas dyads further apart (intermediate VI) had higher PL∶GPS contact ratios. Social networks based on PL contacts showed the fewest connected individuals and lowest mean centrality measures; network metrics were intermediate when based on GPS contacts and greatest when based on VI. Thus, the VI network portrayed animals to be more uniformly and strongly connected than did the PL network. We conclude that simultaneous GPS locations, compared with PLs, substantially underestimate the impact of group membership on direct contact rates of female deer and make networks appear more connected. We also present evidence that deer coming within the general vicinity of each other are less likely to come in close contact if they are in neighboring social groups than deer whose home ranges overlap little if at all. Combined, these results provide evidence that direct transmission of disease agents among female and juvenile white-tailed deer is likely to be constrained both spatially and by social structure, more

Signaling mechanisms underlying the robustness and tunability of the plant immune network

Science.gov (United States)

Kim, Yungil; Tsuda, Kenichi; Igarashi, Daisuke; Hillmer, Rachel A.; Sakakibara, Hitoshi; Myers, Chad L.; Katagiri, Fumiaki

2014-01-01

Summary How does robust and tunable behavior emerge in a complex biological network? We sought to understand this for the signaling network controlling pattern-triggered immunity (PTI) in Arabidopsis. A dynamic network model containing four major signaling sectors, the jasmonate, ethylene, PAD4, and salicylate sectors, which together explain up to 80% of the PTI level, was built using data for dynamic sector activities and PTI levels under exhaustive combinatorial sector perturbations. Our regularized multiple regression model had a high level of predictive power and captured known and unexpected signal flows in the network. The sole inhibitory sector in the model, the ethylene sector, was central to the network robustness via its inhibition of the jasmonate sector. The model's multiple input sites linked specific signal input patterns varying in strength and timing to different network response patterns, indicating a mechanism enabling tunability. PMID:24439900

Prediction of plastic deformation under contact condition by quasi-static and dynamic simulations using explicit finite element analysis

International Nuclear Information System (INIS)

Siswanto, W. A.; Nagentrau, M.; Tobi, A. L. Mohd; Tamin, M. N.

2016-01-01

We compared the quasi-static and dynamic simulation responses on elastic-plastic deformation of advanced alloys using Finite element (FE) method with an explicit numerical algorithm. A geometrical model consisting of a cylinder-on-flat surface contact under a normal load and sliding motion was examined. Two aeroengine materials, Ti-6Al-4V and Super CMV (Cr-Mo-V) alloy, were employed in the FE analysis. The FE model was validated by comparative magnitudes of the FE-predicted maximum contact pressure variation along the contact half-width length with the theoretical Hertzian contact solution. Results show that the (compressive) displacement of the initial contact surface steadily increases for the quasi-static load case, but accumulates at an increasing rate to the maximum level for the dynamic loading. However, the relatively higher stiffness and yield strength of the Super CMV alloy resulted in limited deformation and low plastic strain when compared to the Ti-6Al-4V alloy. The accumulated equivalent plastic strain of the material point at the initial contact position was nearly a thousand times higher for the dynamic load case (for example, 6.592 for Ti-6Al-4V, 1.0 kN) when compared to the quasi-static loading (only 0.0072). During the loading step, the von Mises stress increased with a decreasing and increasing rate for the quasi-static and dynamic load case, respectively. A sudden increase in the stress magnitude to the respective peak value was registered due to the additional constraint to overcome the static friction of the mating surfaces during the sliding step

Prediction of plastic deformation under contact condition by quasi-static and dynamic simulations using explicit finite element analysis

Energy Technology Data Exchange (ETDEWEB)

Siswanto, W. A.; Nagentrau, M.; Tobi, A. L. Mohd [Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, Batu Pahat (Malaysia); Tamin, M. N. [Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, Johor Bahru (Malaysia)

2016-11-15

We compared the quasi-static and dynamic simulation responses on elastic-plastic deformation of advanced alloys using Finite element (FE) method with an explicit numerical algorithm. A geometrical model consisting of a cylinder-on-flat surface contact under a normal load and sliding motion was examined. Two aeroengine materials, Ti-6Al-4V and Super CMV (Cr-Mo-V) alloy, were employed in the FE analysis. The FE model was validated by comparative magnitudes of the FE-predicted maximum contact pressure variation along the contact half-width length with the theoretical Hertzian contact solution. Results show that the (compressive) displacement of the initial contact surface steadily increases for the quasi-static load case, but accumulates at an increasing rate to the maximum level for the dynamic loading. However, the relatively higher stiffness and yield strength of the Super CMV alloy resulted in limited deformation and low plastic strain when compared to the Ti-6Al-4V alloy. The accumulated equivalent plastic strain of the material point at the initial contact position was nearly a thousand times higher for the dynamic load case (for example, 6.592 for Ti-6Al-4V, 1.0 kN) when compared to the quasi-static loading (only 0.0072). During the loading step, the von Mises stress increased with a decreasing and increasing rate for the quasi-static and dynamic load case, respectively. A sudden increase in the stress magnitude to the respective peak value was registered due to the additional constraint to overcome the static friction of the mating surfaces during the sliding step.

A Study on the Effect of the Contact Point and the Contact Force of a Glass Fiber under End-Face Polishing Process

Directory of Open Access Journals (Sweden)

Ying-Chien Tsai

2015-01-01

Full Text Available The offset between the center lines of the polished end-face and the fiber core has a significant effect on coupling efficiency. The initial contact point and the contact force are two of the most important parameters that induce the offset. This study proposes an image assistant method to find the initial contact point and a mathematical model to estimate the contact force when fabricating the double-variable-curvature end-face of single mode glass fiber. The repeatability of finding the initial contact point via the vision assistant program is 0.3 μm. Based on the assumption of a large deflection, a mathematical model is developed to study the relationship between the contact force and the displacement of the lapping film. In order to verify the feasibility of the mathematical model, experiments, as well as DEFORM simulations, are carried out. The results show that the contact forces are alomst linearly proportional to the feed amounts of the lapping film and the errors are less than 9%. By using the method developed in this study, the offset between the grinding end-face and the center line of the fiber core is within 0.15 to 0.35 μm.

A method of non-contact reading code based on computer vision

Science.gov (United States)

Zhang, Chunsen; Zong, Xiaoyu; Guo, Bingxuan

2018-03-01

With the purpose of guarantee the computer information exchange security between internal and external network (trusted network and un-trusted network), A non-contact Reading code method based on machine vision has been proposed. Which is different from the existing network physical isolation method. By using the computer monitors, camera and other equipment. Deal with the information which will be on exchanged, Include image coding ,Generate the standard image , Display and get the actual image , Calculate homography matrix, Image distort correction and decoding in calibration, To achieve the computer information security, Non-contact, One-way transmission between the internal and external network , The effectiveness of the proposed method is verified by experiments on real computer text data, The speed of data transfer can be achieved 24kb/s. The experiment shows that this algorithm has the characteristics of high security, fast velocity and less loss of information. Which can meet the daily needs of the confidentiality department to update the data effectively and reliably, Solved the difficulty of computer information exchange between Secret network and non-secret network, With distinctive originality, practicability, and practical research value.

Timing of product introduction in network economies under heterogeneous demand

DEFF Research Database (Denmark)

Winther, Christian Dahl

This paper studies the introduction of a new and incompatible technology in a spatial market with network externalities. In competition with an established network, the entrant chooses how long to do research and a level of product differentiation, which determine the adoption patterns of consumers...... level of product differentiation that should be chosen by the sponsor of the new technology in equilibrium. Third, the formal relationship between these variables are derived under compatibility.  Fourth, the entering firm's problem is solved by numerical methods to gain insight into the optimal linkage...... between research time and product design....

Contact mechanics: contact area and interfacial separation from small contact to full contact

International Nuclear Information System (INIS)

Yang, C; Persson, B N J

2008-01-01

We present a molecular dynamics study of the contact between a rigid solid with a randomly rough surface and an elastic block with a flat surface. The numerical calculations mainly focus on the contact area and the interfacial separation from small contact (low load) to full contact (high load). For a small load the contact area varies linearly with the load and the interfacial separation depends logarithmically on the load. For a high load the contact area approaches the nominal contact area (i.e. complete contact), and the interfacial separation approaches zero. The numerical results have been compared with analytical theory and experimental results. They are in good agreement with each other. The present findings may be very important for soft solids, e.g. rubber, or for very smooth surfaces, where complete contact can be reached at moderately high loads without plastic deformation of the solids

Interaction of pantographs and contact lines at Shinkansen

Energy Technology Data Exchange (ETDEWEB)

Ikeda, Mitsuru; Uzuka, Tetsuo [Railway Technical Research Institute (RTRI), Tokyo (Japan)

2011-07-15

Tokaido Shinkansen started service between Tokyo and Osaka in 1964. Today, the Shinkansen network comprises 2388 km of lines. The Shinkansen pantograph/contact line system was continuously developed in response to changes in the conditions surrounding railways. Today, there are several unique features. The Auto-transformer feeding system with changeover sections permits electrical connection between pantographs. The Shinkansen train sets are equipped with two pantographs with electrical connection in general. Since due to the electrical connection of pantographs which avoids intense arcing, the mean contact force can be kept low leading to a highly reliable design without serious troubles caused by fatigue. New pantographs achieve very low noise performance, helping the system to be environmental friendly. Today, the Shinkansen network provides stable operation whereby the achievements reported hereafter were implemented. (orig.)

Stochastic Online Learning in Dynamic Networks under Unknown Models

Science.gov (United States)

2016-08-02

The key is to develop online learning strategies at each individual node. Specifically, through local information exchange with its neighbors, each...infinitely repeated game with incomplete information and developed a dynamic pricing strategy referred to as Competitive and Cooperative Demand Learning...Stochastic Online Learning in Dynamic Networks under Unknown Models This research aims to develop fundamental theories and practical algorithms for

Analysis and Reduction of Complex Networks Under Uncertainty

Energy Technology Data Exchange (ETDEWEB)

Knio, Omar M

2014-04-09

This is a collaborative proposal that aims at developing new methods for the analysis and reduction of complex multiscale networks under uncertainty. The approach is based on combining methods of computational singular perturbation (CSP) and probabilistic uncertainty quantification. In deterministic settings, CSP yields asymptotic approximations of reduced-dimensionality “slow manifolds” on which a multiscale dynamical system evolves. Introducing uncertainty raises fundamentally new issues, particularly concerning its impact on the topology of slow manifolds, and means to represent and quantify associated variability. To address these challenges, this project uses polynomial chaos (PC) methods to reformulate uncertain network models, and to analyze them using CSP in probabilistic terms. Specific objectives include (1) developing effective algorithms that can be used to illuminate fundamental and unexplored connections among model reduction, multiscale behavior, and uncertainty, and (2) demonstrating the performance of these algorithms through applications to model problems.

Analysis of deep learning methods for blind protein contact prediction in CASP12.

Science.gov (United States)

Wang, Sheng; Sun, Siqi; Xu, Jinbo

2018-03-01

Here we present the results of protein contact prediction achieved in CASP12 by our RaptorX-Contact server, which is an early implementation of our deep learning method for contact prediction. On a set of 38 free-modeling target domains with a median family size of around 58 effective sequences, our server obtained an average top L/5 long- and medium-range contact accuracy of 47% and 44%, respectively (L = length). A complete implementation has an average accuracy of 59% and 57%, respectively. Our deep learning method formulates contact prediction as a pixel-level image labeling problem and simultaneously predicts all residue pairs of a protein using a combination of two deep residual neural networks, taking as input the residue conservation information, predicted secondary structure and solvent accessibility, contact potential, and coevolution information. Our approach differs from existing methods mainly in (1) formulating contact prediction as a pixel-level image labeling problem instead of an image-level classification problem; (2) simultaneously predicting all contacts of an individual protein to make effective use of contact occurrence patterns; and (3) integrating both one-dimensional and two-dimensional deep convolutional neural networks to effectively learn complex sequence-structure relationship including high-order residue correlation. This paper discusses the RaptorX-Contact pipeline, both contact prediction and contact-based folding results, and finally the strength and weakness of our method. © 2017 Wiley Periodicals, Inc.

Functional brain networks underlying detection and integration of disconfirmatory evidence.

Science.gov (United States)

Lavigne, Katie M; Metzak, Paul D; Woodward, Todd S

2015-05-15

.g., 17s after trial onset) the hemodynamic responses associated with all three networks were simultaneously active. These findings highlight distinct cognitive processes and corresponding functional brain networks underlying stages of disconfirmatory evidence integration, and demonstrate the power of multivariate and multi-experiment methodology in cognitive neuroscience. Copyright © 2015 Elsevier Inc. All rights reserved.

Reliability growth of thin film resistors contact

Directory of Open Access Journals (Sweden)

Lugin A. N.

2010-10-01

Full Text Available Necessity of resistive layer growth under the contact and in the contact zone of resistive element is shown in order to reduce peak values of current flow and power dissipation in the contact of thin film resistor, thereby to increase the resistor stability to parametric and catastrophic failures.

Feasibility of Optical Packet Switched WDM Networks without Packet Synchronisation Under Bursty Traffic Conditions

DEFF Research Database (Denmark)

Fjelde, Tina; Hansen, Peter Bukhave; Kloch, Allan

1999-01-01

We show that complex packet synchronisation may be avoided in optical packetswitched networks. Detailed traffic analysis demonstrates that packet lossratios of 1e-10 are feasible under bursty traffic conditions for a highcapacity network consisting of asynchronously operated add-drop switch...

Common and distinct brain networks underlying verbal and visual creativity.

Science.gov (United States)

Zhu, Wenfeng; Chen, Qunlin; Xia, Lingxiang; Beaty, Roger E; Yang, Wenjing; Tian, Fang; Sun, Jiangzhou; Cao, Guikang; Zhang, Qinglin; Chen, Xu; Qiu, Jiang

2017-04-01

Creativity is imperative to the progression of human civilization, prosperity, and well-being. Past creative researches tends to emphasize the default mode network (DMN) or the frontoparietal network (FPN) somewhat exclusively. However, little is known about how these networks interact to contribute to creativity and whether common or distinct brain networks are responsible for visual and verbal creativity. Here, we use functional connectivity analysis of resting-state functional magnetic resonance imaging data to investigate visual and verbal creativity-related regions and networks in 282 healthy subjects. We found that functional connectivity within the bilateral superior parietal cortex of the FPN was negatively associated with visual and verbal creativity. The strength of connectivity between the DMN and FPN was positively related to both creative domains. Visual creativity was negatively correlated with functional connectivity within the precuneus of the pDMN and right middle frontal gyrus of the FPN, and verbal creativity was negatively correlated with functional connectivity within the medial prefrontal cortex of the aDMN. Critically, the FPN mediated the relationship between the aDMN and verbal creativity, and it also mediated the relationship between the pDMN and visual creativity. Taken together, decreased within-network connectivity of the FPN and DMN may allow for flexible between-network coupling in the highly creative brain. These findings provide indirect evidence for the cooperative role of the default and executive control networks in creativity, extending past research by revealing common and distinct brain systems underlying verbal and visual creative cognition. Hum Brain Mapp 38:2094-2111, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Contact activity and dynamics of the social core

DEFF Research Database (Denmark)

Mones, Enys; Stopczynski, Arkadiusz; Jørgensen, Sune Lehmann

2017-01-01

arising from communication events via phone calls and instant messages, the extent to which these networks differ is not clear. We show here that the network structure of these channels show large structural variations. The various channels account for diverse relationships between pairs of individuals......Humans interact through numerous communication channels to build and maintain social connections: they meet face-to-face, make phone calls or send text messages, and interact via social media. Although it is known that the network of physical contacts, for example, is distinct from the network...... of the network within a low number of steps, in contrast to the nodes on the periphery. The origin and purpose of each communication network also determine the role of their respective central members: highly connected individuals in the person-to-person networks interact with their environment in a regular...

Origin of Peer Influence in Social Networks

Science.gov (United States)

Pinheiro, Flávio L.; Santos, Marta D.; Santos, Francisco C.; Pacheco, Jorge M.

2014-03-01

Social networks pervade our everyday lives: we interact, influence, and are influenced by our friends and acquaintances. With the advent of the World Wide Web, large amounts of data on social networks have become available, allowing the quantitative analysis of the distribution of information on them, including behavioral traits and fads. Recent studies of correlations among members of a social network, who exhibit the same trait, have shown that individuals influence not only their direct contacts but also friends' friends, up to a network distance extending beyond their closest peers. Here, we show how such patterns of correlations between peers emerge in networked populations. We use standard models (yet reflecting intrinsically different mechanisms) of information spreading to argue that empirically observed patterns of correlation among peers emerge naturally from a wide range of dynamics, being essentially independent of the type of information, on how it spreads, and even on the class of underlying network that interconnects individuals. Finally, we show that the sparser and clustered the network, the more far reaching the influence of each individual will be.

Epidemic Wave Dynamics Attributable to Urban Community Structure: A Theoretical Characterization of Disease Transmission in a Large Network

Science.gov (United States)

Eggo, Rosalind M; Lenczner, Michael

2015-01-01

Background Multiple waves of transmission during infectious disease epidemics represent a major public health challenge, but the ecological and behavioral drivers of epidemic resurgence are poorly understood. In theory, community structure—aggregation into highly intraconnected and loosely interconnected social groups—within human populations may lead to punctuated outbreaks as diseases progress from one community to the next. However, this explanation has been largely overlooked in favor of temporal shifts in environmental conditions and human behavior and because of the difficulties associated with estimating large-scale contact patterns. Objective The aim was to characterize naturally arising patterns of human contact that are capable of producing simulated epidemics with multiple wave structures. Methods We used an extensive dataset of proximal physical contacts between users of a public Wi-Fi Internet system to evaluate the epidemiological implications of an empirical urban contact network. We characterized the modularity (community structure) of the network and then estimated epidemic dynamics under a percolation-based model of infectious disease spread on the network. We classified simulated epidemics as multiwave using a novel metric and we identified network structures that were critical to the network’s ability to produce multiwave epidemics. Results We identified robust community structure in a large, empirical urban contact network from which multiwave epidemics may emerge naturally. This pattern was fueled by a special kind of insularity in which locally popular individuals were not the ones forging contacts with more distant social groups. Conclusions Our results suggest that ordinary contact patterns can produce multiwave epidemics at the scale of a single urban area without the temporal shifts that are usually assumed to be responsible. Understanding the role of community structure in epidemic dynamics allows officials to anticipate epidemic

An 8.68% efficiency chemically-doped-free graphene-silicon solar cell using silver nanowires network buried contacts.

Science.gov (United States)

Yang, Lifei; Yu, Xuegong; Hu, Weidan; Wu, Xiaolei; Zhao, Yan; Yang, Deren

2015-02-25

Graphene-silicon (Gr-Si) heterojunction solar cells have been recognized as one of the most low-cost candidates in photovoltaics due to its simple fabrication process. However, the high sheet resistance of chemical vapor deposited (CVD) Gr films is still the most important limiting factor for the improvement of the power conversion efficiency of Gr-Si solar cells, especially in the case of large device-active area. In this work, we have fabricated a novel transparent conductive film by hybriding a monolayer Gr film with silver nanowires (AgNWs) network soldered by the graphene oxide (GO) flakes. This Gr-AgNWs hybrid film exhibits low sheet resistance and larger direct-current to optical conductivity ratio, quite suitable for solar cell fabrication. An efficiency of 8.68% has been achieved for the Gr-AgNWs-Si solar cell, in which the AgNWs network acts as buried contacts. Meanwhile, the Gr-AgNWs-Si solar cells have much better stability than the chemically doped Gr-Si solar cells. These results show a new route for the fabrication of high efficient and stable Gr-Si solar cells.

Structure of the human chromosome interaction network.

Directory of Open Access Journals (Sweden)

Sergio Sarnataro

Full Text Available New Hi-C technologies have revealed that chromosomes have a complex network of spatial contacts in the cell nucleus of higher organisms, whose organisation is only partially understood. Here, we investigate the structure of such a network in human GM12878 cells, to derive a large scale picture of nuclear architecture. We find that the intensity of intra-chromosomal interactions is power-law distributed. Inter-chromosomal interactions are two orders of magnitude weaker and exponentially distributed, yet they are not randomly arranged along the genomic sequence. Intra-chromosomal contacts broadly occur between epigenomically homologous regions, whereas inter-chromosomal contacts are especially associated with regions rich in highly expressed genes. Overall, genomic contacts in the nucleus appear to be structured as a network of networks where a set of strongly individual chromosomal units, as envisaged in the 'chromosomal territory' scenario derived from microscopy, interact with each other via on average weaker, yet far from random and functionally important interactions.

Epidemics in Adaptive Social Networks with Temporary Link Deactivation

Science.gov (United States)

Tunc, Ilker; Shkarayev, Maxim S.; Shaw, Leah B.

2013-04-01

Disease spread in a society depends on the topology of the network of social contacts. Moreover, individuals may respond to the epidemic by adapting their contacts to reduce the risk of infection, thus changing the network structure and affecting future disease spread. We propose an adaptation mechanism where healthy individuals may choose to temporarily deactivate their contacts with sick individuals, allowing reactivation once both individuals are healthy. We develop a mean-field description of this system and find two distinct regimes: slow network dynamics, where the adaptation mechanism simply reduces the effective number of contacts per individual, and fast network dynamics, where more efficient adaptation reduces the spread of disease by targeting dangerous connections. Analysis of the bifurcation structure is supported by numerical simulations of disease spread on an adaptive network. The system displays a single parameter-dependent stable steady state and non-monotonic dependence of connectivity on link deactivation rate.

Crosslinked Remote-Doped Hole-Extracting Contacts Enhance Stability under Accelerated Lifetime Testing in Perovskite Solar Cells.

Science.gov (United States)

Xu, Jixian; Voznyy, Oleksandr; Comin, Riccardo; Gong, Xiwen; Walters, Grant; Liu, Min; Kanjanaboos, Pongsakorn; Lan, Xinzheng; Sargent, Edward H

2016-04-13

A crosslinked hole-extracting electrical contact is reported, which simultaneously improves the stability and lowers the hysteresis of perovskite solar cells. Polymerizable monomers and crosslinking processes are developed to obviate in situ degradation of the under lying perovskite. The crosslinked material is band-aligned with perovskite. The required free carrier density is induced by a high-work-function metal oxide layer atop the device, following a remote-doping strategy. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A method for under-sampled ecological network data analysis: plant-pollination as case study

Directory of Open Access Journals (Sweden)

Peter B. Sorensen

2012-01-01

Full Text Available In this paper, we develop a method, termed the Interaction Distribution (ID method, for analysis of quantitative ecological network data. In many cases, quantitative network data sets are under-sampled, i.e. many interactions are poorly sampled or remain unobserved. Hence, the output of statistical analyses may fail to differentiate between patterns that are statistical artefacts and those which are real characteristics of ecological networks. The ID method can support assessment and inference of under-sampled ecological network data. In the current paper, we illustrate and discuss the ID method based on the properties of plant-animal pollination data sets of flower visitation frequencies. However, the ID method may be applied to other types of ecological networks. The method can supplement existing network analyses based on two definitions of the underlying probabilities for each combination of pollinator and plant species: (1, pi,j: the probability for a visit made by the i’th pollinator species to take place on the j’th plant species; (2, qi,j: the probability for a visit received by the j’th plant species to be made by the i’th pollinator. The method applies the Dirichlet distribution to estimate these two probabilities, based on a given empirical data set. The estimated mean values for pi,j and qi,j reflect the relative differences between recorded numbers of visits for different pollinator and plant species, and the estimated uncertainty of pi,j and qi,j decreases with higher numbers of recorded visits.

Learning gene networks under SNP perturbations using eQTL datasets.

Directory of Open Access Journals (Sweden)

Lingxue Zhang

2014-02-01

Full Text Available The standard approach for identifying gene networks is based on experimental perturbations of gene regulatory systems such as gene knock-out experiments, followed by a genome-wide profiling of differential gene expressions. However, this approach is significantly limited in that it is not possible to perturb more than one or two genes simultaneously to discover complex gene interactions or to distinguish between direct and indirect downstream regulations of the differentially-expressed genes. As an alternative, genetical genomics study has been proposed to treat naturally-occurring genetic variants as potential perturbants of gene regulatory system and to recover gene networks via analysis of population gene-expression and genotype data. Despite many advantages of genetical genomics data analysis, the computational challenge that the effects of multifactorial genetic perturbations should be decoded simultaneously from data has prevented a widespread application of genetical genomics analysis. In this article, we propose a statistical framework for learning gene networks that overcomes the limitations of experimental perturbation methods and addresses the challenges of genetical genomics analysis. We introduce a new statistical model, called a sparse conditional Gaussian graphical model, and describe an efficient learning algorithm that simultaneously decodes the perturbations of gene regulatory system by a large number of SNPs to identify a gene network along with expression quantitative trait loci (eQTLs that perturb this network. While our statistical model captures direct genetic perturbations of gene network, by performing inference on the probabilistic graphical model, we obtain detailed characterizations of how the direct SNP perturbation effects propagate through the gene network to perturb other genes indirectly. We demonstrate our statistical method using HapMap-simulated and yeast eQTL datasets. In particular, the yeast gene network

Contact fatigue in rolling-element bearings

CSIR Research Space (South Africa)

Fernandes, PJL

1997-06-01

Full Text Available to the "cyclone pitting effect" also observed in gear teeth \\[1\\]. The initiation of surface cracks under rollin~sliding contact can be significantly accelerated by the presence of stress concentration sites on the contact surf... formed by rolling and rollin~sliding contact fatigue may progress to form a more severe form of damage known as flaking \\[3\\]. This results in the formation of large, irregular pits which cause rapid deterioration...

A multi-period distribution network design model under demand uncertainty

Science.gov (United States)

Tabrizi, Babak H.; Razmi, Jafar

2013-05-01

Supply chain management is taken into account as an inseparable component in satisfying customers' requirements. This paper deals with the distribution network design (DND) problem which is a critical issue in achieving supply chain accomplishments. A capable DND can guarantee the success of the entire network performance. However, there are many factors that can cause fluctuations in input data determining market treatment, with respect to short-term planning, on the one hand. On the other hand, network performance may be threatened by the changes that take place within practicing periods, with respect to long-term planning. Thus, in order to bring both kinds of changes under control, we considered a new multi-period, multi-commodity, multi-source DND problem in circumstances where the network encounters uncertain demands. The fuzzy logic is applied here as an efficient tool for controlling the potential customers' demand risk. The defuzzifying framework leads the practitioners and decision-makers to interact with the solution procedure continuously. The fuzzy model is then validated by a sensitivity analysis test, and a typical problem is solved in order to illustrate the implementation steps. Finally, the formulation is tested by some different-sized problems to show its total performance.

An effective method to improve the robustness of small-world networks under attack

International Nuclear Information System (INIS)

Zhang Zheng-Zhen; Xu Wen-Jun; Lin Jia-Ru; Zeng Shang-You

2014-01-01

In this study, the robustness of small-world networks to three types of attack is investigated. Global efficiency is introduced as the network coefficient to measure the robustness of a small-world network. The simulation results prove that an increase in rewiring probability or average degree can enhance the robustness of the small-world network under all three types of attack. The effectiveness of simultaneously increasing both rewiring probability and average degree is also studied, and the combined increase is found to significantly improve the robustness of the small-world network. Furthermore, the combined effect of rewiring probability and average degree on network robustness is shown to be several times greater than that of rewiring probability or average degree individually. This means that small-world networks with a relatively high rewiring probability and average degree have advantages both in network communications and in good robustness to attacks. Therefore, simultaneously increasing rewiring probability and average degree is an effective method of constructing realistic networks. Consequently, the proposed method is useful to construct efficient and robust networks in a realistic scenario. (interdisciplinary physics and related areas of science and technology)

Investigation of subsurface fatigue crack in PEEK shaft under one-point rolling contact by using 2.5D layer observation method

Directory of Open Access Journals (Sweden)

KOIKE Hitonobu

2017-01-01

Full Text Available Subsurface fatigue cracks under rolling contact area of the PEEK shaft against an alumina bearing’s ball were investigated for application of frictional part in mechanical element in special situations such as chemical environments. In order to explore the flaking process of the PEEK shaft, the rolling contact fatigue tests were carried out by using a one-point radial loading rolling contact machine. The flaking occurred on the rolling track of the PEEK shaft at approximate 4⨉105 fatigue cycles. The subsurface fatigue crack propagation was investigated by using 2.5-Dimension layer observation method. The flaking was caused by the propagations of surface cracks and subsurface shear cracks, and the flaking shape was half-ellipse. Moreover, beach marks as fatigue crack propagation in the flaking were observed.

Robustness of the Drinking Water Distribution Network under Changing Future Demand

NARCIS (Netherlands)

Agudelo-Vera, C.; Blokker, M.; Vreeburg, J.; Bongard, T.; Hillegers, S.; Van der Hoek, J.P.

2014-01-01

A methodology to determine the robustness of the drinking water distribution system is proposed. The performance of three networks under ten future demand scenarios was tested, using head loss and residence time as indicators. The scenarios consider technological and demographic changes. Daily

Mathematical Modeling of Contact Problems of Elasticity Theory with Unilateral Discrete Contact

Directory of Open Access Journals (Sweden)

I. V. Stankevich

2015-01-01

Full Text Available Development and operation of modern machinery and latest technology require reliable estimates of the strength characteristics of the critical elements of structures and technological equipment under the impact of high-intensity thermomechanical loading, accompanied, as a rule, by complex contact interaction. Mathematical modeling of stress-strain state of such parts and components in the contact area, based on adequate mathematical models, modern numerical methods and efficient algorithms that implement the direct determination of displacement fields, strains and stresses, is the main tool that allows fast acquisition of data required for the calculations of strength and durability. The paper considers an algorithm for constructing the numerical solution of the contact problem of elasticity theory in relation to the body, which has an obvious one-sided discrete contact interaction with an elastic half-space. The proposed algorithm is specially designed to have a correction of the tangential forces at discrete contact points, allowing us to achieve sufficiently accurate implementation of the adopted law of friction. The algorithm is embedded in a general finite element technology, with which the application code is generated. Numerical study of discrete unilateral contact interaction of an elastic plate and a rigid half-space showed a high efficiency of the developed algorithm and the application code that implements it.

Ground Contact Analysis for Korea’s Fictitious Lunar Orbiter Mission

Directory of Open Access Journals (Sweden)

Young-Joo Song

2013-12-01

Full Text Available In this research, the ground contact opportunity for the fictitious low lunar orbiter is analyzed to prepare for a future Korean lunar orbiter mission. The ground contact opportunity is basically derived from geometrical relations between the typical ground stations at the Earth, the relative positions of the Earth and Moon, and finally, the lunar orbiter itself. Both the cut-off angle and the orbiter’s Line of Sight (LOS conditions (weather orbiter is located at near or far side of the Moon seen from the Earth are considered to determine the ground contact opportunities. Four KOMPSAT Ground Stations (KGSs are assumed to be Korea’s future Near Earth Networks (NENs to support lunar missions, and world-wide separated Deep Space Networks (DSNs are also included during the contact availability analysis. As a result, it is concluded that about 138 times of contact will be made between the orbiter and the Daejeon station during 27.3 days of prediction time span. If these contact times are converted into contact duration, the duration is found to be about 8.55 days, about 31.31% of 27.3 days. It is discovered that selected four KGSs cannot provide continuous tracking of the lunar orbiter, meaning that international collaboration is necessary to track Korea’s future lunar orbiter effectively. Possible combinations of world-wide separated DSNs are also suggested to compensate for the lack of contact availability with only four KGSs, as with primary and backup station concepts. The provided algorithm can be easily modified to support any type of orbit around the Moon, and therefore, the presented results could aid further progress in the design field of Korea’s lunar orbiter missions.

Network maintenance

CERN Multimedia

GS Department

2009-01-01

A site-wide network maintenance operation has been scheduled for Saturday 28 February. Most of the network devices of the general purpose network will be upgraded to a newer software version, in order to improve our network monitoring capabilities. This will result in a series of short (2-5 minutes) random interruptions everywhere on the CERN sites throughout the day. This upgrade will not affect the Computer Centre itself, Building 613, the Technical Network and the LHC experiments, dedicated networks at the pits. For further details of this intervention, please contact Netops by phone 74927 or e-mail mailto:Netops@cern.ch. IT/CS Group

Network maintenance

CERN Multimedia

IT Department

2009-01-01

A site wide network maintenance has been scheduled for Saturday 28 February. Most of the network devices of the General Purpose network will be upgraded to a newer software version, in order to improve our network monitoring capabilities. This will result in a series of short (2-5 minutes) random interruptions everywhere on the CERN sites along this day. This upgrade will not affect: the Computer centre itself, building 613, the Technical Network and the LHC experiments dedicated networks at the pits. Should you need more details on this intervention, please contact Netops by phone 74927 or email mailto:Netops@cern.ch. IT/CS Group

A review of micro-contact physics, materials, and failure mechanisms in direct-contact RF MEMS switches

International Nuclear Information System (INIS)

Basu, A; Adams, G G; McGruer, N E

2016-01-01

Direct contact, ohmic MEMS switches for RF applications have several advantages over other conventional switching devices. Advantages include lower insertion loss, higher isolation, and better switching figure-of-merit (cut-off frequency). The most important aspect of a direct-contact RF MEMS switch is the metal microcontact which can dictate the lifetime and reliability of the switch. Therefore, an understanding of contact reliability is essential for developing robust MEMS switches. This paper discusses and reviews the most important work done over the past couple of decades toward understanding ohmic micro-contacts. We initially discuss the contact mechanics and multi-physics models for studying Hertzian and multi-asperity contacts. We follow this with a discussion on models and experiments for studying adhesion. We then discuss experimental setups and the development of contact test stations by various groups for accelerated testing of microcontacts, as well as for analysis of contact reliability issues. Subsequently, we analyze a number of material transfer mechanisms in microcontacts under hot and cold switching conditions. We finally review the material properties that can help determine the selection of contact materials. A trade-off between contact resistance and high reliability is almost always necessary during selection of contact material; this paper discusses how the choice of materials can help address such trade-offs. (paper)

Optimization of temporal networks under uncertainty

CERN Document Server

Wiesemann, Wolfram

2012-01-01

Many decision problems in Operations Research are defined on temporal networks, that is, workflows of time-consuming tasks whose processing order is constrained by precedence relations. For example, temporal networks are used to model projects, computer applications, digital circuits and production processes. Optimization problems arise in temporal networks when a decision maker wishes to determine a temporal arrangement of the tasks and/or a resource assignment that optimizes some network characteristic (e.g. the time required to complete all tasks). The parameters of these optimization probl

Head-disk interface nanotribology for Tbit/inch2 recording densities: near-contact and contact recording

Science.gov (United States)

Vakis, Antonis I.; Polycarpou, Andreas A.

2010-06-01

In the effort to achieve Tbit/inch2 recording densities, thermal fly-height control (TFC) nanotechnology was developed to effectively reduce the clearance (which is of the order of a few nanometres) at the head-disk interface (HDI) of hard-disk drives. In this work, we present a model of the HDI that can predict the dynamic flying and nanotribological contacting behaviour, allowing for accurate predictions and characterization of the operating regime as a function of TFC actuation. A geometric model for TFC is presented and an improved definition of contact at the interface is developed in the presence of nanoscale topographical roughness and dynamic microwaviness. A new methodology is proposed for the calculation of the nominal area of contact, which affects both near- and at-contact behaviour, while the stiffening of the air bearing force with TFC actuation is also accounted for. Slider behaviour is analysed by quantifying the approach, jump-to-contact, lubricant and solid contact regimes of operation and identifying the critical and optimum TFC actuations. The feasibility of near-contact, light molecularly thin lubricant contact versus solid contact recording is explored under the effect of the interfacial forces and stresses present at the HDI. The clearance and the state of vibrations are analysed and design guidelines are proposed for improved performance.

Head-disk interface nanotribology for Tbit/inch2 recording densities: near-contact and contact recording

International Nuclear Information System (INIS)

Vakis, Antonis I; Polycarpou, Andreas A

2010-01-01

In the effort to achieve Tbit/inch 2 recording densities, thermal fly-height control (TFC) nanotechnology was developed to effectively reduce the clearance (which is of the order of a few nanometres) at the head-disk interface (HDI) of hard-disk drives. In this work, we present a model of the HDI that can predict the dynamic flying and nanotribological contacting behaviour, allowing for accurate predictions and characterization of the operating regime as a function of TFC actuation. A geometric model for TFC is presented and an improved definition of contact at the interface is developed in the presence of nanoscale topographical roughness and dynamic microwaviness. A new methodology is proposed for the calculation of the nominal area of contact, which affects both near- and at-contact behaviour, while the stiffening of the air bearing force with TFC actuation is also accounted for. Slider behaviour is analysed by quantifying the approach, jump-to-contact, lubricant and solid contact regimes of operation and identifying the critical and optimum TFC actuations. The feasibility of near-contact, light molecularly thin lubricant contact versus solid contact recording is explored under the effect of the interfacial forces and stresses present at the HDI. The clearance and the state of vibrations are analysed and design guidelines are proposed for improved performance.

Network Formation under the Threat of Disruption

NARCIS (Netherlands)

Hoyer, B.

2013-01-01

The studies in this thesis are focused on the impact the presence of a network disruptor has on network formation models. In particular, we build two theoretical models to study the effect of network disruption on network formation and test the effect network disruption has on equilibrium selection

Predicting epidemic risk from past temporal contact data.

Directory of Open Access Journals (Sweden)

Eugenio Valdano

2015-03-01

Full Text Available Understanding how epidemics spread in a system is a crucial step to prevent and control outbreaks, with broad implications on the system's functioning, health, and associated costs. This can be achieved by identifying the elements at higher risk of infection and implementing targeted surveillance and control measures. One important ingredient to consider is the pattern of disease-transmission contacts among the elements, however lack of data or delays in providing updated records may hinder its use, especially for time-varying patterns. Here we explore to what extent it is possible to use past temporal data of a system's pattern of contacts to predict the risk of infection of its elements during an emerging outbreak, in absence of updated data. We focus on two real-world temporal systems; a livestock displacements trade network among animal holdings, and a network of sexual encounters in high-end prostitution. We define the node's loyalty as a local measure of its tendency to maintain contacts with the same elements over time, and uncover important non-trivial correlations with the node's epidemic risk. We show that a risk assessment analysis incorporating this knowledge and based on past structural and temporal pattern properties provides accurate predictions for both systems. Its generalizability is tested by introducing a theoretical model for generating synthetic temporal networks. High accuracy of our predictions is recovered across different settings, while the amount of possible predictions is system-specific. The proposed method can provide crucial information for the setup of targeted intervention strategies.

Contact angles of water-repellent porous media inferred by tensiometer - TDR probe measurement under controlled wetting and drying cycles

DEFF Research Database (Denmark)

Subedi, Shaphal; Kawamoto, Ken; Komatsu, Toshiko

2013-01-01

with water, eventually allowing water imbibition. However, the effect of the reduction in CA with soil-water contact time on the water retention function of hydrophobic media is not yet fully understood. In this study, water retention characteristics were measured using a hanging water column apparatus...... retention curves. For both water-repellent VAS and hydrophobized sand samples, the calculated CA–SWRC increased with increasing WR. This was determined from both the water drop penetration time and the initial contact angle (CAi) by the sessile drop method. Calculated CA–SWRC values ranged from 20° to 48......-filled pore distributions under controlled wetting and drying cycles was found on calculating the soil water capacity and pore size density as a function of water potential....

Threshold model of cascades in empirical temporal networks

Science.gov (United States)

Karimi, Fariba; Holme, Petter

2013-08-01

Threshold models try to explain the consequences of social influence like the spread of fads and opinions. Along with models of epidemics, they constitute a major theoretical framework of social spreading processes. In threshold models on static networks, an individual changes her state if a certain fraction of her neighbors has done the same. When there are strong correlations in the temporal aspects of contact patterns, it is useful to represent the system as a temporal network. In such a system, not only contacts but also the time of the contacts are represented explicitly. In many cases, bursty temporal patterns slow down disease spreading. However, as we will see, this is not a universal truth for threshold models. In this work we propose an extension of Watts’s classic threshold model to temporal networks. We do this by assuming that an agent is influenced by contacts which lie a certain time into the past. I.e., the individuals are affected by contacts within a time window. In addition to thresholds in the fraction of contacts, we also investigate the number of contacts within the time window as a basis for influence. To elucidate the model’s behavior, we run the model on real and randomized empirical contact datasets.

The Economics of Networks: theory and empirics

NARCIS (Netherlands)

M.J. van der Leij (Marco)

2006-01-01

textabstractWherever we are, networks are all around us. The roads that we travel form a network. The websites that we visit form an enormous information network. But, above all, we are part of a network ourselves, the network of social contacts and relations. These networks play an

Synchronisation of networked Kuramoto oscillators under stable Lévy noise

Science.gov (United States)

Kalloniatis, Alexander C.; Roberts, Dale O.

2017-01-01

We study the Kuramoto model on several classes of network topologies examining the dynamics under the influence of Lévy noise. Such noise exhibits heavier tails than Gaussian and allows us to understand how 'shocks' influence the individual oscillator and collective system behaviour. Skewed α-stable Lévy noise, equivalent to fractional diffusion perturbations, are considered. We perform numerical simulations for Erdős-Rényi (ER) and Barabási-Albert (BA) scale free networks of size N = 1000 while varying the Lévy index α for the noise. We find that synchrony now assumes a surprising variety of forms, not seen for Gaussian-type noise, and changing with α: a noise-generated drift, a smooth α dependence of the point of cross-over of ER and BA networks in the degree of synchronisation, and a severe loss of synchronisation at low values of α. We also show that this robustness of the BA network across most values of α can also be understood as a consequence of the Laplacian of the graph working within the fractional Fokker-Planck equation of the linearised system, close to synchrony, with both eigenvalues and eigenvectors alternately contributing in different regimes of α.

Optimal information dissemination strategy to promote preventive behaviors in multilayer epidemic networks.

Science.gov (United States)

Shakeri, Heman; Sahneh, Faryad Darabi; Scoglio, Caterina; Poggi-Corradini, Pietro; Preciado, Victor M

2015-06-01

Launching a prevention campaign to contain the spread of infection requires substantial financial investments; therefore, a trade-off exists between suppressing the epidemic and containing costs. Information exchange among individuals can occur as physical contacts (e.g., word of mouth, gatherings), which provide inherent possibilities of disease transmission, and non-physical contacts (e.g., email, social networks), through which information can be transmitted but the infection cannot be transmitted. Contact network (CN) incorporates physical contacts, and the information dissemination network (IDN) represents non-physical contacts, thereby generating a multilayer network structure. Inherent differences between these two layers cause alerting through CN to be more effective but more expensive than IDN. The constraint for an epidemic to die out derived from a nonlinear Perron-Frobenius problem that was transformed into a semi-definite matrix inequality and served as a constraint for a convex optimization problem. This method guarantees a dying-out epidemic by choosing the best nodes for adopting preventive behaviors with minimum monetary resources. Various numerical simulations with network models and a real-world social network validate our method.

Dynamics of social contagions with limited contact capacity.

Science.gov (United States)

Wang, Wei; Shu, Panpan; Zhu, Yu-Xiao; Tang, Ming; Zhang, Yi-Cheng

2015-10-01

Individuals are always limited by some inelastic resources, such as time and energy, which restrict them to dedicate to social interaction and limit their contact capacities. Contact capacity plays an important role in dynamics of social contagions, which so far has eluded theoretical analysis. In this paper, we first propose a non-Markovian model to understand the effects of contact capacity on social contagions, in which each adopted individual can only contact and transmit the information to a finite number of neighbors. We then develop a heterogeneous edge-based compartmental theory for this model, and a remarkable agreement with simulations is obtained. Through theory and simulations, we find that enlarging the contact capacity makes the network more fragile to behavior spreading. Interestingly, we find that both the continuous and discontinuous dependence of the final adoption size on the information transmission probability can arise. There is a crossover phenomenon between the two types of dependence. More specifically, the crossover phenomenon can be induced by enlarging the contact capacity only when the degree exponent is above a critical degree exponent, while the final behavior adoption size always grows continuously for any contact capacity when degree exponent is below the critical degree exponent.

Osteosynthesis with plate of under contact (LC DCP) in long bones

International Nuclear Information System (INIS)

Suarez Romero, Fabio; Bocanegra Navia, Sergio; Nino C, Jose Maria; Tapias Urrego Alexander

2002-01-01

In this study 98 patients were evaluated to who are carried out osteosynthesis with plates of under contact in the hospital military of Bogota, between January of 1996 and January of the 2002, with diagnostic of open fractures, fracture closed and pseudoarthrosis that committed the humerus, the cube and the radius, the metacarpal, the femur and the tibia. Of the total, 67,3% corresponded to open fractures and 32,7% they were closed fractures; as for its origin, 54,1% was hurt by firearm, 28,6% for accident rail car and 17,3% for direct trauma. The segment more affected it was the forearm with 43 cases. In the open fractures the cultivation was positive in 11,2%. The average of surgical washed was of 3,2. 110 plates were placed in 98 patients. In 58% one carries out boarding of the fracture focus, and in 41,8% limited boarding. The pursuit average was of 28,2 months. It was not any difference statistically significant between the boarding type and the time of consolidation. It doesn't present osteomyelitis neither septic loosening in the patient's treaties

Algorithm Design on Network Game of Chinese Chess

Science.gov (United States)

Xianmei, Fang

This paper describes the current situation of domestic network game. Contact the present condition of the local network game currently, we inquired to face to a multithread tcp client and server, such as Chinese chess, according to the information, and study the contents and meanings. Combining the Java of basic knowledge, the article study the compiling procedure facing to the object according to the information in Java Swing usage, and the method of the network procedure. The article researched the method and processes of the network procedure carry on the use of Sprocket under the Java Swing. Understood the basic process of compiling procedure using Java and how to compile a network procedure. The most importance is how a pair of machines correspondence-C/S the service system-is carried out. From here, we put forward the data structure,the basic calculate way of the network game- Chinese chess, and how to design and realize the server and client of that procedure. The online games -- chess design can be divided into several modules as follows: server module, client module and the control module.

Evaluation of Blast Resistance of Fiber Reinforced Composite Specimens under Contact Blast Load

Science.gov (United States)

Janota, O.; Foglar, M.

2017-09-01

This paper presents results of experimental programme which took place in 2014, 2015 and 2016. Experiments were focused on the resistance of full scale concrete panels subjected to contact blast loading. Specimens were loaded by contact blast by plastic explosive. All specimens were reinforced concrete slabs made of fiber concrete. Basalt mesh and textile sheets were added to some of the experiments for creating more heterogeneous material to achieve better resistance of the specimens. Evaluation of experiments was mainly focused on the damaged area on the contact side and soffit of the specimens. Dependency of the final damage of concrete panels on the weight of explosive and concrete strength was assessed.

Contact force structure and force chains in 3D sheared granular systems

Science.gov (United States)

Mair, Karen; Jettestuen, Espen; Abe, Steffen

2010-05-01

Faults often exhibit accumulations of granular debris, ground up to create a layer of rock flour or fault gouge separating the rigid fault walls. Numerical simulations and laboratory experiments of sheared granular materials, suggest that applied loads are preferentially transmitted across such systems by transient force networks that carry enhanced forces. The characterisation of such features is important since their nature and persistence almost certainly influence the macroscopic mechanical stability of these systems and potentially that of natural faults. 3D numerical simulations of granular shear are a valuable investigation tool since they allow us to track individual particle motions, contact forces and their evolution during applied shear, that are difficult to view directly in laboratory experiments or natural fault zones. In characterising contact force distributions, it is important to use global structure measures that allow meaningful comparisons of granular systems having e.g. different grain size distributions, as may be expected at different stages of a fault's evolution. We therefore use a series of simple measures to characterise the structure, such as distributions and correlations of contact forces that can be mapped onto a force network percolation problem as recently proposed by Ostojic and coworkers for 2D granular systems. This allows the use of measures from percolation theory to both define and characterise the force networks. We demonstrate the application of this method to 3D simulations of a sheared granular material. Importantly, we then compare our measure of the contact force structure with macroscopic frictional behaviour measured at the boundaries of our model to determine the influence of the force networks on macroscopic mechanical stability.

Suppression of anomalous synchronization and nonstationary behavior of neural network under small-world topology

Science.gov (United States)

Boaretto, B. R. R.; Budzinski, R. C.; Prado, T. L.; Kurths, J.; Lopes, S. R.

2018-05-01

It is known that neural networks under small-world topology can present anomalous synchronization and nonstationary behavior for weak coupling regimes. Here, we propose methods to suppress the anomalous synchronization and also to diminish the nonstationary behavior occurring in weakly coupled neural network under small-world topology. We consider a network of 2000 thermally sensitive identical neurons, based on the model of Hodgkin-Huxley in a small-world topology, with the probability of adding non local connection equal to p = 0 . 001. Based on experimental protocols to suppress anomalous synchronization, as well as nonstationary behavior of the neural network dynamics, we make use of (i) external stimulus (pulsed current); (ii) biologic parameters changing (neuron membrane conductance changes); and (iii) body temperature changes. Quantification analysis to evaluate phase synchronization makes use of the Kuramoto's order parameter, while recurrence quantification analysis, particularly the determinism, computed over the easily accessible mean field of network, the local field potential (LFP), is used to evaluate nonstationary states. We show that the methods proposed can control the anomalous synchronization and nonstationarity occurring for weak coupling parameter without any effect on the individual neuron dynamics, neither in the expected asymptotic synchronized states occurring for large values of the coupling parameter.

Temperature dependence of contact resistance at metal/MWNT interface

Energy Technology Data Exchange (ETDEWEB)

Lee, Sang-Eui; Moon, Kyoung-Seok; Sohn, Yoonchul, E-mail: yoonchul.son@samsung.com [Materials Research Center, Samsung Advanced Institute of Technology, Samsung Electronics, Suwon 443-803 (Korea, Republic of)

2016-07-11

Although contact resistance of carbon nanotube (CNT) is one of the most important factors for practical application of electronic devices, a study regarding temperature dependence on contact resistance of CNTs with metal electrodes has not been found. Here, we report an investigation of contact resistance at multiwalled nanotube (MWNT)/Ag interface as a function of temperature, using MWNT/polydimethylsiloxane (PDMS) composite. Electrical resistance of MWNT/PDMS composite revealed negative temperature coefficient (NTC). Excluding the contact resistance with Ag electrode, the NTC effect became less pronounced, showing lower intrinsic resistivity with the activation energy of 0.019 eV. Activation energy of the contact resistance of MWNT/Ag interface was determined to be 0.04 eV, two times larger than that of MWNT-MWNT network. The increase in the thermal fluctuation assisted electron tunneling is attributed to conductivity enhancement at both MWNT/MWNT and MWNT/Ag interfaces with increasing temperature.

Modeling the Propagation of Mobile Phone Virus under Complex Network

Science.gov (United States)

Yang, Wei; Wei, Xi-liang; Guo, Hao; An, Gang; Guo, Lei

2014-01-01

Mobile phone virus is a rogue program written to propagate from one phone to another, which can take control of a mobile device by exploiting its vulnerabilities. In this paper the propagation model of mobile phone virus is tackled to understand how particular factors can affect its propagation and design effective containment strategies to suppress mobile phone virus. Two different propagation models of mobile phone viruses under the complex network are proposed in this paper. One is intended to describe the propagation of user-tricking virus, and the other is to describe the propagation of the vulnerability-exploiting virus. Based on the traditional epidemic models, the characteristics of mobile phone viruses and the network topology structure are incorporated into our models. A detailed analysis is conducted to analyze the propagation models. Through analysis, the stable infection-free equilibrium point and the stability condition are derived. Finally, considering the network topology, the numerical and simulation experiments are carried out. Results indicate that both models are correct and suitable for describing the spread of two different mobile phone viruses, respectively. PMID:25133209

Dynamical interplay between awareness and epidemic spreading in multiplex networks

OpenAIRE

Granell, Clara; Gomez, Sergio; Arenas, Alex

2013-01-01

We present the analysis of the interrelation between two processes accounting for the spreading of an epidemics, and the information awareness to prevent its infection, on top of multiplex networks. This scenario is representative of an epidemic process spreading on a network of persistent real contacts, and a cyclic information awareness process diffusing in the network of virtual social contacts between the same individuals. The topology corresponds to a multiplex network where two diffusiv...

Enhancing network performance under single link failure with AS-disjoint BGP extension

DEFF Research Database (Denmark)

Manolova, Anna Vasileva; Romeral, S.; Ruepp, Sarah Renée

2009-01-01

In this paper we propose an enhancement of the BGP protocol for obtaining AS-disjoint paths in GMPLS multi-domain networks. We evaluate the benefits of having AS-disjoint paths under single inter-domain link failure for two main applications: routing of future connection requests during routing...... protocol re-convergence and applying multi-domain restoration as survivability mechanism in case of a single link failure. The proposed BGP modification is a simple and effective solution for disjoint path selection in connection-oriented multi-domain networks. Our results show that applying the proper...

Sustainable and Resilient Supply Chain Network Design under Disruption Risks

Directory of Open Access Journals (Sweden)

Sonia Irshad Mari

2014-09-01

Full Text Available Sustainable supply chain network design is a rich area for academic research that is still in its infancy and has potential to affect supply chain performance. Increasing regulations for carbon and waste management are forcing firms to consider their supply chains from ecological and social objectives, but in reality, however, facilities and the links connecting them are disrupted from time to time, due to poor weather, natural or manmade disasters or a combination of any other factors. Supply chain systems drop their sustainability objectives while coping with these unexpected disruptions. Hence, the new challenges for supply chain managers are to design an efficient and effective supply chain network that will be resilient enough to bounce back from any disruption and that also should have sufficient vigilance to offer same sustainability under a disruption state. This paper focuses on ecological sustainability, because an environmental focus in a supply chain system is more important and also links with other pillars of sustainability, as the products need to be produced, packed and transported in an ethical way, which should not harm social balance and the environment. Owing to importance of the considered issue, this paper attempts to introduce a network optimization model for a sustainable and resilient supply chain network by incorporating (1 sustainability via carbon emissions and embodied carbon footprints and (2 resilience by incorporating location-specific risks. The proposed goal programming (GP model optimizes the total cost, while considering the resilience and sustainability of the supply chain network.

A performance study of unmanned aerial vehicle-based sensor networks under cyber attack

Science.gov (United States)

Puchaty, Ethan M.

In UAV-based sensor networks, an emerging area of interest is the performance of these networks under cyber attack. This study seeks to evaluate the performance trade-offs from a System-of-Systems (SoS) perspective between various UAV communications architecture options in the context two missions: tracking ballistic missiles and tracking insurgents. An agent-based discrete event simulation is used to model a sensor communication network consisting of UAVs, military communications satellites, ground relay stations, and a mission control center. Network susceptibility to cyber attack is modeled with probabilistic failures and induced data variability, with performance metrics focusing on information availability, latency, and trustworthiness. Results demonstrated that using UAVs as routers increased network availability with a minimal latency penalty and communications satellite networks were best for long distance operations. Redundancy in the number of links between communication nodes helped mitigate cyber-caused link failures and add robustness in cases of induced data variability by an adversary. However, when failures were not independent, redundancy and UAV routing were detrimental in some cases to network performance. Sensitivity studies indicated that long cyber-caused downtimes and increasing failure dependencies resulted in build-ups of failures and caused significant degradations in network performance.

Consensus formation on coevolving networks: groups' formation and structure

International Nuclear Information System (INIS)

Kozma, Balazs; Barrat, Alain

2008-01-01

We study the effect of adaptivity on a social model of opinion dynamics and consensus formation. We analyse how the adaptivity of the network of contacts between agents to the underlying social dynamics affects the size and topological properties of groups and the convergence time to the stable final state. We find that, while on static networks these properties are determined by percolation phenomena, on adaptive networks the rewiring process leads to different behaviors: adaptive rewiring fosters group formation by enhancing communication between agents of similar opinion, though it also makes possible the division of clusters. We show how the convergence time is determined by the characteristic time of link rearrangement. We finally investigate how the adaptivity yields nontrivial correlations between the internal topology and the size of the groups of agreeing agents

Temporal networks

Science.gov (United States)

Holme, Petter; Saramäki, Jari

2012-10-01

A great variety of systems in nature, society and technology-from the web of sexual contacts to the Internet, from the nervous system to power grids-can be modeled as graphs of vertices coupled by edges. The network structure, describing how the graph is wired, helps us understand, predict and optimize the behavior of dynamical systems. In many cases, however, the edges are not continuously active. As an example, in networks of communication via e-mail, text messages, or phone calls, edges represent sequences of instantaneous or practically instantaneous contacts. In some cases, edges are active for non-negligible periods of time: e.g., the proximity patterns of inpatients at hospitals can be represented by a graph where an edge between two individuals is on throughout the time they are at the same ward. Like network topology, the temporal structure of edge activations can affect dynamics of systems interacting through the network, from disease contagion on the network of patients to information diffusion over an e-mail network. In this review, we present the emergent field of temporal networks, and discuss methods for analyzing topological and temporal structure and models for elucidating their relation to the behavior of dynamical systems. In the light of traditional network theory, one can see this framework as moving the information of when things happen from the dynamical system on the network, to the network itself. Since fundamental properties, such as the transitivity of edges, do not necessarily hold in temporal networks, many of these methods need to be quite different from those for static networks. The study of temporal networks is very interdisciplinary in nature. Reflecting this, even the object of study has many names-temporal graphs, evolving graphs, time-varying graphs, time-aggregated graphs, time-stamped graphs, dynamic networks, dynamic graphs, dynamical graphs, and so on. This review covers different fields where temporal graphs are considered

Phenotypic stability and plasticity in GMP-derived cells as determined by their underlying regulatory network.

Science.gov (United States)

Ramírez, Carlos; Mendoza, Luis

2018-04-01

Blood cell formation has been recognized as a suitable system to study celular differentiation mainly because of its experimental accessibility, and because it shows characteristics such as hierarchical and gradual bifurcated patterns of commitment, which are present in several developmental processes. Although hematopoiesis has been extensively studied and there is a wealth of molecular and cellular data about it, it is not clear how the underlying molecular regulatory networks define or restrict cellular differentiation processes. Here, we infer the molecular regulatory network that controls the differentiation of a blood cell subpopulation derived from the granulocyte-monocyte precursor (GMP), comprising monocytes, neutrophils, eosinophils, basophils and mast cells. We integrate published qualitative experimental data into a model to describe temporal expression patterns observed in GMP-derived cells. The model is implemented as a Boolean network, and its dynamical behavior is studied. Steady states of the network can be clearly identified with the expression profiles of monocytes, mast cells, neutrophils, basophils, and eosinophils, under wild-type and mutant backgrounds. All scripts are publicly available at https://github.com/caramirezal/RegulatoryNetworkGMPModel. lmendoza@biomedicas.unam.mx. Supplementary data are available at Bioinformatics online.

Standard test method for damage to contacting solid surfaces under fretting conditions

CERN Document Server

American Society for Testing and Materials. Philadelphia

2010-01-01

1.1 This test method covers the studying or ranking the susceptibility of candidate materials to fretting corrosion or fretting wear for the purposes of material selection for applications where fretting corrosion or fretting wear can limit serviceability. 1.2 This test method uses a tribological bench test apparatus with a mechanism or device that will produce the necessary relative motion between a contacting hemispherical rider and a flat counterface. The rider is pressed against the flat counterface with a loading mass. The test method is intended for use in room temperature air, but future editions could include fretting in the presence of lubricants or other environments. 1.3 The purpose of this test method is to rub two solid surfaces together under controlled fretting conditions and to quantify the damage to both surfaces in units of volume loss for the test method. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5...

Identifiability of tree-child phylogenetic networks under a probabilistic recombination-mutation model of evolution.

Science.gov (United States)

Francis, Andrew; Moulton, Vincent

2018-06-07

Phylogenetic networks are an extension of phylogenetic trees which are used to represent evolutionary histories in which reticulation events (such as recombination and hybridization) have occurred. A central question for such networks is that of identifiability, which essentially asks under what circumstances can we reliably identify the phylogenetic network that gave rise to the observed data? Recently, identifiability results have appeared for networks relative to a model of sequence evolution that generalizes the standard Markov models used for phylogenetic trees. However, these results are quite limited in terms of the complexity of the networks that are considered. In this paper, by introducing an alternative probabilistic model for evolution along a network that is based on some ground-breaking work by Thatte for pedigrees, we are able to obtain an identifiability result for a much larger class of phylogenetic networks (essentially the class of so-called tree-child networks). To prove our main theorem, we derive some new results for identifying tree-child networks combinatorially, and then adapt some techniques developed by Thatte for pedigrees to show that our combinatorial results imply identifiability in the probabilistic setting. We hope that the introduction of our new model for networks could lead to new approaches to reliably construct phylogenetic networks. Copyright © 2018 Elsevier Ltd. All rights reserved.

Defining an essence of structure determining residue contacts in proteins.

Science.gov (United States)

Sathyapriya, R; Duarte, Jose M; Stehr, Henning; Filippis, Ioannis; Lappe, Michael

2009-12-01

The network of native non-covalent residue contacts determines the three-dimensional structure of a protein. However, not all contacts are of equal structural significance, and little knowledge exists about a minimal, yet sufficient, subset required to define the global features of a protein. Characterisation of this "structural essence" has remained elusive so far: no algorithmic strategy has been devised to-date that could outperform a random selection in terms of 3D reconstruction accuracy (measured as the Ca RMSD). It is not only of theoretical interest (i.e., for design of advanced statistical potentials) to identify the number and nature of essential native contacts-such a subset of spatial constraints is very useful in a number of novel experimental methods (like EPR) which rely heavily on constraint-based protein modelling. To derive accurate three-dimensional models from distance constraints, we implemented a reconstruction pipeline using distance geometry. We selected a test-set of 12 protein structures from the four major SCOP fold classes and performed our reconstruction analysis. As a reference set, series of random subsets (ranging from 10% to 90% of native contacts) are generated for each protein, and the reconstruction accuracy is computed for each subset. We have developed a rational strategy, termed "cone-peeling" that combines sequence features and network descriptors to select minimal subsets that outperform the reference sets. We present, for the first time, a rational strategy to derive a structural essence of residue contacts and provide an estimate of the size of this minimal subset. Our algorithm computes sparse subsets capable of determining the tertiary structure at approximately 4.8 A Ca RMSD with as little as 8% of the native contacts (Ca-Ca and Cb-Cb). At the same time, a randomly chosen subset of native contacts needs about twice as many contacts to reach the same level of accuracy. This "structural essence" opens new avenues in the

Slip-rolling resistance of novel Zr(C,N) thin film coatings under high Hertzian contact pressures

Energy Technology Data Exchange (ETDEWEB)

Manier, Charles-Alix

2010-08-24

Today, coatings are used in many applications ranging from the decoration purposes to the improvement of efficiency such as in machining tools, medical tools, computer devices (hard disks) and many more. Especially the automotive industry anticipates a benefit in using coatings for example in powertrains and gears where the mechanical components are stressed under slip-rolling motion. A cost effective option to increase efficiency is based on the increase of the load carrying capacity by thin film coatings. It would also represent a way towards downsizing. In the work presented here, a small review concerning rolling contact fatigue of coatings was performed. Experimentally it is then shown, that crystalline Zr(C,N) coatings can be slip-rolling resistant at 120 C in factory fill engine oil up to ten million cycles under average Hertzian contact pressures up to P{sub 0mean} = 1.94 GPa (P{sub 0max} = 2.91 GPa). Basically, it represents here the doubling of the normal force acting on the surface compared to uncoated steel traditionally lubricated with fully formulated oil. Typically, the coated substrates are made of the quenched and tempered bearing steel Cronidur 30. The Zr(C,N) coatings were fully characterized using different characterisation techniques in order to understand the difference in slip-rolling resistance under those high tribological demands. Effectively, the slip-rolling resistance of different batches of the Zr(C,N) coatings is evaluated using a defined and powerful testing procedure. Different results of lifetime were achieved without fundamental changes of the deposition procedure. The characterisation achieved permits the identification of microstructural disparities which should affect the load carrying capacity of the coating. Moreover, the efficiency of the high slip-rolling resistant Zr(C,N) coating was considered not only with respect to the improvement of the load carrying capacity of the substrate but also in terms of tribological

Non-conformal contact mechanical characteristic analysis on spherical components

Energy Technology Data Exchange (ETDEWEB)

Zhen-zhi, G.; Bin, H.; Zheng-ming, G.; Feng-mei, Y.; Jin, Q [The 2. Artillery Engineering Univ., Xi' an (China)

2017-03-15

Non-conformal spherical-contact mechanical problems is a three-dimensional coordination or similar to the coordination spherical contact. Due to the complexity of the problem of spherical-contact and difficulties of solving higher-order partial differential equations, problems of three-dimensional coordination or similar to the coordination spherical-contact is still no exact analytical method for solving. It is based on three-dimensional taper model is proposed a model based on the contour surface of the spherical contact and concluded of the formula of the contact pressure and constructed of finite element model by contact pressure distribution under the non-conformal spherical. The results shows spherical contact model can reflect non-conformal spherical-contacting mechanical problems more than taper-contacting model, and apply for the actual project.

Sheep movement networks and the transmission of infectious diseases.

Directory of Open Access Journals (Sweden)

Victoriya V Volkova

2010-06-01

Full Text Available Various approaches have been used to investigate how properties of farm contact networks impact on the transmission of infectious diseases. The potential for transmission of an infection through a contact network can be evaluated in terms of the basic reproduction number, R(0. The magnitude of R(0 is related to the mean contact rate of a host, in this case a farm, and is further influenced by heterogeneities in contact rates of individual hosts. The latter can be evaluated as the second order moments of the contact matrix (variances in contact rates, and co-variance between contacts to and from individual hosts. Here we calculate these quantities for the farms in a country-wide livestock network: >15,000 Scottish sheep farms in each of 4 years from July 2003 to June 2007. The analysis is relevant to endemic and chronic infections with prolonged periods of infectivity of affected animals, and uses different weightings of contacts to address disease scenarios of low, intermediate and high animal-level prevalence.Analysis of networks of Scottish farms via sheep movements from July 2003 to June 2007 suggests that heterogeneities in movement patterns (variances and covariances of rates of movement on and off the farms make a substantial contribution to the potential for the transmission of infectious diseases, quantified as R(0, within the farm population. A small percentage of farms (80% and these farms could be efficiently targeted by interventions aimed at reducing spread of diseases via animal movement.

Credal Networks under Maximum Entropy

OpenAIRE

Lukasiewicz, Thomas

2013-01-01

We apply the principle of maximum entropy to select a unique joint probability distribution from the set of all joint probability distributions specified by a credal network. In detail, we start by showing that the unique joint distribution of a Bayesian tree coincides with the maximum entropy model of its conditional distributions. This result, however, does not hold anymore for general Bayesian networks. We thus present a new kind of maximum entropy models, which are computed sequentially. ...

STI patients are effective recruiters of undiagnosed cases of HIV: results of a social contact recruitment study in Malawi.

Science.gov (United States)

Rosenberg, Nora E; Kamanga, Gift; Pettifor, Audrey E; Bonongwe, Naomi; Mapanje, Clement; Rutstein, Sarah E; Ward, Michelle; Hoffman, Irving F; Martinson, Francis; Miller, William C

2014-04-15

Patients with newly diagnosed HIV may be part of social networks with elevated prevalence of undiagnosed HIV infection. Social network recruitment by persons with newly diagnosed HIV may efficiently identify undiagnosed cases of HIV infection. We assessed social network recruitment as a strategy for identifying undiagnosed cases of HIV infection. In a sexually transmitted infection (STI) clinic in Lilongwe, Malawi, 3 groups of 45 "seeds" were enrolled: STI patients with newly diagnosed HIV, STI patients who were HIV-uninfected, and community controls. Seeds were asked to recruit up to 5 social "contacts" (sexual or nonsexual). Mean number of contacts recruited per group was calculated. HIV prevalence ratios (PRs) and number of contacts needed to test to identify 1 new case of HIV were compared between groups using generalized estimating equations with exchangeable correlation matrices. Mean number of contacts recruited was 1.3 for HIV-infected clinic seeds, 1.8 for HIV-uninfected clinic seeds, and 2.3 for community seeds. Contacts of HIV-infected clinic seeds had a higher HIV prevalence (PR: 3.2, 95% confidence interval: 1.3 to 7.8) than contacts of community seeds, but contacts of HIV-uninfected clinic seeds did not (PR: 1.1, 95% confidence interval: 0.4 to 3.3). Results were similar when restricted to nonsexual contacts. To identify 1 new case of HIV, it was necessary to test 8 contacts of HIV-infected clinic seeds, 10 contacts of HIV-uninfected clinic seeds, and 18 contacts of community seeds. Social contact recruitment by newly diagnosed STI patients efficiently led to new HIV diagnoses. Research to replicate findings and guide implementation is needed.

Helping Behavior in Executives' Global Networks

DEFF Research Database (Denmark)

Miller, Stewart; Mors, Marie Louise; McDonald, Michael

2014-01-01

Drawing on research on helping behavior in networks at the upper echelons, we develop and test theory about helping behavior in senior executive networks. We examine the location and relational dependence of the network contact. Our results reveal that executives are more likely to perceive...... insiders in their network to be helpful, but geographic location has no effect on expectations of receiving help. With regards to relational dependence: executives who are more dependent on their contacts are more likely to perceive them to be helpful. We also look at whether perceived helpfulness affects...... an executive’s willingness to engage in risky new business development -- an important performance indicator - and indeed find that those executives that perceive their networks to be helpful are more likely to be willing to take risky decisions. We test these arguments using primary data on 1845 relationships...

Thermo-Mechanical Properties of Semi-Degradable Poly(β-amino ester)-co-Methyl Methacrylate Networks under Simulated Physiological Conditions

Science.gov (United States)

Safranski, David L.; Crabtree, Jacob C.; Huq, Yameen R.; Gall, Ken

2011-01-01

Poly(β-amino ester) networks are being explored for biomedical applications, but they may lack the mechanical properties necessary for long term implantation. The objective of this study is to evaluate the effect of adding methyl methacrylate on networks' mechanical properties under simulated physiological conditions. The networks were synthesized in two parts: (1) a biodegradable crosslinker was formed from a diacrylate and amine, (2) and then varying concentrations of methyl methacrylate were added prior to photopolymerizing the network. Degradation rate, mechanical properties, and glass transition temperature were studied as a function of methyl methacrylate composition. The crosslinking density played a limited role on mechanical properties for these networks, but increasing methyl methacrylate concentration improved the toughness by several orders of magnitude. Under simulated physiological conditions, networks showed increasing toughness or sustained toughness as degradation occurred. This work establishes a method of creating degradable networks with tailorable toughness while undergoing partial degradation. PMID:21966028

Improvements to Integrated Tradespace Analysis of Communications Architectures (ITACA) Network Loading Analysis Tool

Science.gov (United States)

Lee, Nathaniel; Welch, Bryan W.

2018-01-01

NASA's SCENIC project aims to simplify and reduce the cost of space mission planning by replicating the analysis capabilities of commercially licensed software which are integrated with relevant analysis parameters specific to SCaN assets and SCaN supported user missions. SCENIC differs from current tools that perform similar analyses in that it 1) does not require any licensing fees, 2) will provide an all-in-one package for various analysis capabilities that normally requires add-ons or multiple tools to complete. As part of SCENIC's capabilities, the ITACA network loading analysis tool will be responsible for assessing the loading on a given network architecture and generating a network service schedule. ITACA will allow users to evaluate the quality of service of a given network architecture and determine whether or not the architecture will satisfy the mission's requirements. ITACA is currently under development, and the following improvements were made during the fall of 2017: optimization of runtime, augmentation of network asset pre-service configuration time, augmentation of Brent's method of root finding, augmentation of network asset FOV restrictions, augmentation of mission lifetimes, and the integration of a SCaN link budget calculation tool. The improvements resulted in (a) 25% reduction in runtime, (b) more accurate contact window predictions when compared to STK(Registered Trademark) contact window predictions, and (c) increased fidelity through the use of specific SCaN asset parameters.

28 CFR 810.1 - Supervision contact requirements.

Science.gov (United States)

2010-07-01

... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Supervision contact requirements. 810.1 Section 810.1 Judicial Administration COURT SERVICES AND OFFENDER SUPERVISION AGENCY FOR THE DISTRICT OF COLUMBIA COMMUNITY SUPERVISION: ADMINISTRATIVE SANCTIONS § 810.1 Supervision contact requirements. If you are an offender under supervision by th...

Increase of reliability of contact networks of electric transport, due to increase of strength of the joint unit of pipes of different diameters

Science.gov (United States)

Sabitov, L. S.; Kashapov, N. F.; Gilmanshin, I. R.; Gatiyatov, I. Z.; Kuznetsov, I. L.

2017-09-01

The feature of the stress state of the supports of the contact networks is the presence of a joint of pipes of different diameters, the ultimate state of which is determined, as a rule, the strength of the weld. The proposed unit allows to increase the reliability and strength of the connection and also exclude the presence of a weld bead on the outer surface of the pipe of smaller diameter in the place of its attachment to the upper end of the support ring.

Temporal node centrality in complex networks

Science.gov (United States)

Kim, Hyoungshick; Anderson, Ross

2012-02-01

Many networks are dynamic in that their topology changes rapidly—on the same time scale as the communications of interest between network nodes. Examples are the human contact networks involved in the transmission of disease, ad hoc radio networks between moving vehicles, and the transactions between principals in a market. While we have good models of static networks, so far these have been lacking for the dynamic case. In this paper we present a simple but powerful model, the time-ordered graph, which reduces a dynamic network to a static network with directed flows. This enables us to extend network properties such as vertex degree, closeness, and betweenness centrality metrics in a very natural way to the dynamic case. We then demonstrate how our model applies to a number of interesting edge cases, such as where the network connectivity depends on a small number of highly mobile vertices or edges, and show that our centrality definition allows us to track the evolution of connectivity. Finally we apply our model and techniques to two real-world dynamic graphs of human contact networks and then discuss the implication of temporal centrality metrics in the real world.

Optimal Retrofit Scheme for Highway Network under Seismic Hazards

Directory of Open Access Journals (Sweden)

Yongxi Huang

2014-06-01

Full Text Available Many older highway bridges in the United States (US are inadequate for seismic loads and could be severely damaged or collapsed in a relatively small earthquake. According to the most recent American Society of Civil Engineers’ infrastructure report card, one-third of the bridges in the US are rated as structurally deficient and many of these structurally deficient bridges are located in seismic zones. To improve this situation, at-risk bridges must be identified and evaluated and effective retrofitting programs should be in place to reduce their seismic vulnerabilities. In this study, a new retrofit strategy decision scheme for highway bridges under seismic hazards is developed and seamlessly integrate the scenario-based seismic analysis of bridges and the traffic network into the proposed optimization modeling framework. A full spectrum of bridge retrofit strategies is considered based on explicit structural assessment for each seismic damage state. As an empirical case study, the proposed retrofit strategy decision scheme is utilized to evaluate the bridge network in one of the active seismic zones in the US, Charleston, South Carolina. The developed modeling framework, on average, will help increase network throughput traffic capacity by 45% with a cost increase of only $15million for the Mw 5.5 event and increase the capacity fourfold with a cost of only $32m for the Mw 7.0 event.

Slow, bursty dynamics as a consequence of quenched network topologies

Science.gov (United States)

Ådor, Géza

2014-04-01

Bursty dynamics of agents is shown to appear at criticality or in extended Griffiths phases, even in case of Poisson processes. I provide numerical evidence for a power-law type of intercommunication time distributions by simulating the contact process and the susceptible-infected-susceptible model. This observation suggests that in the case of nonstationary bursty systems, the observed non-Poissonian behavior can emerge as a consequence of an underlying hidden Poissonian network process, which is either critical or exhibits strong rare-region effects. On the contrary, in time-varying networks, rare-region effects do not cause deviation from the mean-field behavior, and heterogeneity-induced burstyness is absent.

Slow, bursty dynamics as a consequence of quenched network topologies.

Science.gov (United States)

Ódor, Géza

2014-04-01

Bursty dynamics of agents is shown to appear at criticality or in extended Griffiths phases, even in case of Poisson processes. I provide numerical evidence for a power-law type of intercommunication time distributions by simulating the contact process and the susceptible-infected-susceptible model. This observation suggests that in the case of nonstationary bursty systems, the observed non-Poissonian behavior can emerge as a consequence of an underlying hidden Poissonian network process, which is either critical or exhibits strong rare-region effects. On the contrary, in time-varying networks, rare-region effects do not cause deviation from the mean-field behavior, and heterogeneity-induced burstyness is absent.

Phase transitions in cooperative coinfections: Simulation results for networks and lattices

Science.gov (United States)

Grassberger, Peter; Chen, Li; Ghanbarnejad, Fakhteh; Cai, Weiran

2016-04-01

We study the spreading of two mutually cooperative diseases on different network topologies, and with two microscopic realizations, both of which are stochastic versions of a susceptible-infected-removed type model studied by us recently in mean field approximation. There it had been found that cooperativity can lead to first order transitions from spreading to extinction. However, due to the rapid mixing implied by the mean field assumption, first order transitions required nonzero initial densities of sick individuals. For the stochastic model studied here the results depend strongly on the underlying network. First order transitions are found when there are few short but many long loops: (i) No first order transitions exist on trees and on 2-d lattices with local contacts. (ii) They do exist on Erdős-Rényi (ER) networks, on d -dimensional lattices with d ≥4 , and on 2-d lattices with sufficiently long-ranged contacts. (iii) On 3-d lattices with local contacts the results depend on the microscopic details of the implementation. (iv) While single infected seeds can always lead to infinite epidemics on regular lattices, on ER networks one sometimes needs finite initial densities of infected nodes. (v) In all cases the first order transitions are actually "hybrid"; i.e., they display also power law scaling usually associated with second order transitions. On regular lattices, our model can also be interpreted as the growth of an interface due to cooperative attachment of two species of particles. Critically pinned interfaces in this model seem to be in different universality classes than standard critically pinned interfaces in models with forbidden overhangs. Finally, the detailed results mentioned above hold only when both diseases propagate along the same network of links. If they use different links, results can be rather different in detail, but are similar overall.

Social network predictors of latrine ownership.

Science.gov (United States)

Shakya, Holly B; Christakis, Nicholas A; Fowler, James H

2015-01-01

Poor sanitation, including the lack of clean functioning toilets, is a major factor contributing to morbidity and mortality from infectious diseases in the developing world. We examine correlates of latrine ownership in rural India with a focus on social network predictors. Participants from 75 villages provided the names of their social contacts as well as their own relevant demographic and household characteristics. Using these measures, we test whether the latrine ownership of an individual's social contacts is a significant predictor of individual latrine ownership. We also investigate whether network centrality significantly predicts latrine ownership, and if so, whether it moderates the relationship between the latrine ownership of the individual and that of her social contacts. Our results show that, controlling for the standard predictors of latrine ownership such as caste, education, and income, individuals are more likely to own latrines if their social contacts own latrines. Interaction models suggest that this relationship is stronger among those of the same caste, the same education, and those with stronger social ties. We also find that more central individuals are more likely to own latrines, but the correlation in latrine ownership between social contacts is strongest among individuals on the periphery of the network. Although more data is needed to determine how much the clustering of latrine ownership may be caused by social influence, the results here suggest that interventions designed to promote latrine ownership should consider focusing on those at the periphery of the network. The reason is that they are 1) less likely to own latrines and 2) more likely to exhibit the same behavior as their social contacts, possibly as a result of the spread of latrine adoption from one person to another. Copyright © 2014 Elsevier Ltd. All rights reserved.

Polymer-interaction driven diffusionof eyeshadow in soft contact lenses.

Science.gov (United States)

Tavazzi, Silvia; Rossi, Alessandra; Picarazzi, Sara; Ascagni, Miriam; Farris, Stefano; Borghesi, Alessandro

2017-10-01

Soft contact lenses used for the correction of ametropia are often made of hydrogel and silicone-hydrogel materials. Since they are placed directly on the surface of the eye and they are hydrated by tears, eye cosmetics can compromise the lens performance and, even worse, can be transported from an external environment to the ocular surface through the contact lens. The diffusion of the dye component of a purple eyeshadow in soft contact lenses of different materials is here evaluated. Diffusivity is found to be typically higher in silicone-hydrogels than in hydrogels. In hydrogels, diffusivity is greater in the case of lower oxygen transmissibility. Despite differences between materials, absorbed mass of dye is much larger (10-100 times) than the expected mass by simple hydration and swelling of the contact lens. The most contaminated materials are also resistant to cleaning solutions. The results indicate that, notwithstanding the complexity of contact lens networks, diffusion of dye is found to follow Fick's law and it is driven by polymer-dye interaction, which governs lens hydration and swelling. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Temporal characterisation of the network of Danish cattle movements and its implication for disease control: 2000–2009

DEFF Research Database (Denmark)

Mweu, Marshal M.; Fournié, Guillaume; Hisham Beshara Halasa, Tariq

2013-01-01

-world properties in March–April 2001 as well as in 24 other months during the period October 2006 to December 2009. The network was sparsely connected with markets being the key influential holdings. Its vulnerability to removal of markets suggests that targeting highly connected holdings during epidemics should......Social network analysis provides a valuable framework for understanding the dynamics of diseases on networks as well as a means for defining effective control measures. An understanding of the underlying contact pattern for a susceptible population is advisable before embarking on any strategy...

In situ recording of particle network formation in liquids by ion conductivity measurements.

Science.gov (United States)

Pfaffenhuber, Christian; Sörgel, Seniz; Weichert, Katja; Bele, Marjan; Mundinger, Tabea; Göbel, Marcus; Maier, Joachim

2011-09-21

The formation of fractal silica networks from a colloidal initial state was followed in situ by ion conductivity measurements. The underlying effect is a high interfacial lithium ion conductivity arising when silica particles are brought into contact with Li salt-containing liquid electrolytes. The experimental results were modeled using Monte Carlo simulations and tested using confocal fluorescence laser microscopy and ζ-potential measurements.

Hop-by-HopWorm Propagation with Carryover Epidemic Model in Mobile Sensor Networks

Directory of Open Access Journals (Sweden)

Jun-Won Ho

2015-10-01

Full Text Available In the internet, a worm is usually propagated in a random multi-hop contact manner. However, the attacker will not likely select this random multi-hop propagation approach in a mobile sensor network. This is because multi-hop worm route paths to random vulnerable targets can be often breached due to node mobility, leading to failure of fast worm spread under this strategy. Therefore, an appropriate propagation strategy is needed for mobile sensor worms. To meet this need, we discuss a hop-by-hop worm propagation model in mobile sensor networks. In a hop-by-hop worm propagation model, benign nodes are infected by worm in neighbor-to-neighbor spread manner. Since worm infection occurs in hop-by-hop contact, it is not substantially affected by a route breach incurred by node mobility. We also propose the carryover epidemic model to deal with the worm infection quota deficiency that might occur when employing an epidemic model in a mobile sensor network. We analyze worm infection capability under the carryover epidemic model. Moreover, we simulate hop-by-hop worm propagation with carryover epidemic model by using an ns-2 simulator. The simulation results demonstrate that infection quota carryovers are seldom observed where a node’s maximum speed is no less than 20 m/s.

Wetting dynamics at high values of contact line speed

OpenAIRE

Пономарев, К. О.; Феоктистов, Дмитрий Владимирович; Орлова, Евгения Георгиевна

2015-01-01

Experimental results analyses of dynamic contact angle change under the conditions of substrate wetting by distilled water at high values of the contact line speed was conducted. Three spreading modes for copper substrates with different roughness were selected: drop formation, spreading and equilibrium contact angle formation. Peculiarity of droplet spreading on superhydrophobic surface is found. It consists in a monotonic increase of the advancing dynamic contact angle. The effect of the dr...

The effects of online social networks on tacit knowledge transmission

Science.gov (United States)

Zhu, Hong-Miao; Zhang, Sheng-Tai; Jin, Zhen

2016-01-01

Due to the popular use of online social networks in today's world, how to propagate employees' tacit knowledge via online social networks has attracted managers' attention, which is critical to enhance the competitiveness of firms. In this paper, we propose a tacit knowledge transmission model on networks with even mixing based on the propagation property of tacit knowledge and the application of online social networks. We consider two routes of transmission, which are contact through online social networks and face-to-face physical contact, and derive the threshold that governs whether or not a kind of tacit knowledge can be shared in an organization with few initial employees who have acquired it. The impact of the degree distribution of the users' contact network on the transmission is investigated analytically. Some numerical simulations are presented to support the theoretical results. We perform the sensitivity analysis of the threshold in terms of the propagation parameters and confirm that online social networks contribute significantly to enhancing the transmission of tacit knowledge among employees.

Strategies for a better performance of RPL under mobility in wireless sensor networks

Science.gov (United States)

Latib, Z. A.; Jamil, A.; Alduais, N. A. M.; Abdullah, J.; Audah, L. H. M.; Alias, R.

2017-09-01

A Wireless Sensor Network (WSN) is usually stationary, which the network comprises of static nodes. The increase demand for mobility in various applications such as environmental monitoring, medical, home automation, and military, raises the question how IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) would perform under these mobility applications. This paper aims to understand performance of RPL and come out with strategies for a better performance of RPL in mobility scenarios. Because of this, this paper evaluates the performance of the RPL protocol under three different scenarios: sink and sensor nodes are static, static sink and mobile sensor nodes, and sink and sensor nodes are mobile. The network scenarios are implemented in Cooja simulator. A WSN consists of 25 sensor nodes and one sink node is configured in the simulation environment. The simulation is varied over different packet rates and ContikiMAC's Clear Channel Assessment (CCA) rate. As the performance metric, RPL is evaluated in term of packet delivery ratio (PDR), power consumption and packet rates. The simulation results show RPL provides a poor PDR in the mobility scenarios when compared to the static scenario. In addition, RPL consumes more power and increases duty-cycle rate to support mobility when compared to the static scenario. Based on the findings, we suggest three strategies for a better performance of RPL in mobility scenarios. First, RPL should operates at a lower packet rates when implemented in the mobility scenarios. Second, RPL should be implemented with a higher duty-cycle rate. Lastly, the sink node should be positioned as much as possible in the center of the mobile network.

Near-optimal Downlink precoding of a MISO system for a secondary network under the SINR constraints of a primary network

KAUST Repository

Park, Kihong

2013-04-01

In this paper, we study a multiple-input single-output cognitive radio (CR) system where only the primary base station (BS) has multiple antennas. We consider a rate maximization problem of the secondary network under signal-to-interference-plus-noise-ratio constraints on the primary network in order to guarantee the quality-of-service for the latter network. While the interference due to the secondary transmission in the conventional underlay CR approach may severely degrade the performance of the primary network, we propose a primary BS-aided approach in which the primary BS helps relay the secondary users\\' signals instead of allowing them to communicate with each other via a direct path between them. In addition, an algorithm to find a near-optimal beamforming solution at the primary BS is proposed. Finally, based on some selected numerical results, we show that the proposed scheme outperforms the conventional underlay CR configuration over a wide transmit power range. © 2013 IEEE.

Micro and macro contact mechanics for interacting asperities

Indian Academy of Sciences (India)

assigned to one surface making the other surface perfectly flat an assumption .... pressure at the middle of contact and 2a being the contact length. p0 and a are related by ... Since this third eye is found to be an isotropic point under hydrostatic.

Temporal networks

CERN Document Server

Saramäki, Jari

2013-01-01

The concept of temporal networks is an extension of complex networks as a modeling framework to include information on when interactions between nodes happen. Many studies of the last decade examine how the static network structure affect dynamic systems on the network. In this traditional approach  the temporal aspects are pre-encoded in the dynamic system model. Temporal-network methods, on the other hand, lift the temporal information from the level of system dynamics to the mathematical representation of the contact network itself. This framework becomes particularly useful for cases where there is a lot of structure and heterogeneity both in the timings of interaction events and the network topology. The advantage compared to common static network approaches is the ability to design more accurate models in order to explain and predict large-scale dynamic phenomena (such as, e.g., epidemic outbreaks and other spreading phenomena). On the other hand, temporal network methods are mathematically and concept...

A Social Network Analysis of Occupational Segregation

DEFF Research Database (Denmark)

Buhai, Ioan Sebastian; van der Leij, Marco

We develop a social network model of occupational segregation between different social groups, generated by the existence of positive inbreeding bias among individuals from the same group. If network referrals are important for job search, then expected homophily in the contact network structure...

Sliding contact fracture of dental ceramics: Principles and validation

Science.gov (United States)

Ren, Linlin; Zhang, Yu

2014-01-01

Ceramic prostheses are subject to sliding contact under normal and tangential loads. Accurate prediction of the onset of fracture at two contacting surfaces holds the key to greater long-term performance of these prostheses. In this study, building on stress analysis of Hertzian contact and considering fracture criteria for linear elastic materials, a constitutive fracture mechanics relation was developed to incorporate the critical fracture load with the contact geometry, coefficient of friction and material fracture toughness. Critical loads necessary to cause fracture under a sliding indenter were calculated from the constitutive equation, and compared with the loads predicted from elastic stress analysis in conjunction with measured critical load for frictionless normal contact—a semi-empirical approach. The major predictions of the models were calibrated with experimentally determined critical loads of current and future dental ceramics after contact with a rigid spherical slider. Experimental results conform with the trends predicted by the models. PMID:24632538

The contact sport of rough surfaces

Science.gov (United States)

Carpick, Robert W.

2018-01-01

Describing the way two surfaces touch and make contact may seem simple, but it is not. Fully describing the elastic deformation of ideally smooth contacting bodies, under even low applied pressure, involves second-order partial differential equations and fourth-rank elastic constant tensors. For more realistic rough surfaces, the problem becomes a multiscale exercise in surface-height statistics, even before including complex phenomena such as adhesion, plasticity, and fracture. A recent research competition, the “Contact Mechanics Challenge” (1), was designed to test various approximate methods for solving this problem. A hypothetical rough surface was generated, and the community was invited to model contact with this surface with competing theories for the calculation of properties, including contact area and pressure. A supercomputer-generated numerical solution was kept secret until competition entries were received. The comparison of results (2) provides insights into the relative merits of competing models and even experimental approaches to the problem.

Development of Shale Gas Supply Chain Network under Market Uncertainties

Directory of Open Access Journals (Sweden)

Jorge Chebeir

2017-02-01

Full Text Available The increasing demand of energy has turned the shale gas and shale oil into one of the most promising sources of energy in the United States. In this article, a model is proposed to address the long-term planning problem of the shale gas supply chain under uncertain conditions. A two-stage stochastic programming model is proposed to describe and optimize the shale gas supply chain network. Inherent uncertainty in final products’ prices, such as natural gas and natural gas liquids (NGL, is treated through the utilization of a scenario-based method. A binomial option pricing model is utilized to approximate the stochastic process through the generation of scenario trees. The aim of the proposed model is to generate an appropriate and realistic supply chain network configuration as well as scheduling of different operations throughout the planning horizon of a shale gas development project.

Occupational contact urticaria and protein contact dermatitis.

Science.gov (United States)

Doutre, Marie-Sylvie

2005-01-01

Irritant dermatitis and eczema are the most prevalent occupational skin diseases. Less common are immediate contact reactions such as contact urticaria and protein contact dermatitis. Occupational contact urticaria can be subdivided into two categories, immunological and non immunological. However, some agents can induce these two types of reactions. Contact urticaria to natural rubber latex is particularly frequent among health care personnel, but contact urticaria to a wide variety of other substances occurs in many other occupations. Among those at risk are cooks, bakers, butchers, restaurant personnel, veterinarians, hairdressers, florists, gardeners, and forestry workers. Protein contact dermatitis in some of these occupations is caused principally by proteins of animal or plant origin, especially among individuals with a history of atopic dermatitis. Diagnosis requires careful interrogation, clinical examination and skin tests (open tests and prick tests with immediate lecture) to identify a particular contact allergen.

THE DYNAMIC INTERACTION OF THE MOVING CONTACTING SURFACES AT THE EXAMPLE OF THE ELECTRIC ROLLING STOCK CURRENT COLLECTOR

Directory of Open Access Journals (Sweden)

M. O. Babiak

2009-07-01

Full Text Available The process of mutual moving and contacting of surfaces of current collecting pantograph elements and contact network is considered taking into account the particularities of inf1uence of speed and acceleration parameters, determination of which will allow to forecast mathematically the wear-out degree of contacting elements.

AcconPred: Predicting Solvent Accessibility and Contact Number Simultaneously by a Multitask Learning Framework under the Conditional Neural Fields Model.

Science.gov (United States)

Ma, Jianzhu; Wang, Sheng

2015-01-01

The solvent accessibility of protein residues is one of the driving forces of protein folding, while the contact number of protein residues limits the possibilities of protein conformations. The de novo prediction of these properties from protein sequence is important for the study of protein structure and function. Although these two properties are certainly related with each other, it is challenging to exploit this dependency for the prediction. We present a method AcconPred for predicting solvent accessibility and contact number simultaneously, which is based on a shared weight multitask learning framework under the CNF (conditional neural fields) model. The multitask learning framework on a collection of related tasks provides more accurate prediction than the framework trained only on a single task. The CNF method not only models the complex relationship between the input features and the predicted labels, but also exploits the interdependency among adjacent labels. Trained on 5729 monomeric soluble globular protein datasets, AcconPred could reach 0.68 three-state accuracy for solvent accessibility and 0.75 correlation for contact number. Tested on the 105 CASP11 domain datasets for solvent accessibility, AcconPred could reach 0.64 accuracy, which outperforms existing methods.

Mechanical deformation of atomic-scale metallic contacts: Structure and mechanisms

DEFF Research Database (Denmark)

Sørensen, Mads Reinholdt; Brandbyge, Mads; Jacobsen, Karsten Wedel

1998-01-01

We have simulated the mechanical deformation of atomic-scale metallic contacts under tensile strain using molecular dynamics and effective medium theory potentials. The evolution of the structure of the contacts and the underlying deformation mechanisms are described along with the calculated......, but vacancies can be permanently present. The transition states and energies for slip mechanisms have been determined using the nudged elastic band method, and we find a size-dependent crossover from a dislocation-mediated slip to a homogeneous slip when the contact diameter becomes less than a few nm. We show...

Visual method for detecting critical damage in railway contact strips

Science.gov (United States)

Judek, S.; Skibicki, J.

2018-05-01

Ensuring an uninterrupted supply of power in the electric traction is vital for the safety of this important transport system. For this purpose, monitoring and diagnostics of the technical condition of the vehicle’s power supply elements are becoming increasingly common. This paper presents a new visual method for detecting contact strip damage, based on measurement and analysis of the movement of the overhead contact line (OCL) wire. A measurement system configuration with a 2D camera was proposed. The experimental method has shown that contact strips damage can be detected by transverse displacement signal analysis. It has been proven that the velocity signal numerically established on that basis has a comparable level in the case of identical damage, regardless of its location on the surface of the contact strip. The proposed method belongs to the group of contact-less measurements, so it does not require interference with the structure of the catenary network nor the mounting of sensors in its vicinity. Measurement of displacements of the contact wire in 2D space makes it possible to combine the functions of existing diagnostic stands assessing the correctness of the mean contact force control adjustment of the current collector with the elements of the contact strip diagnostics, which involves detecting their damage which may result in overhead contact line rupture.

The importance of accurately modelling human interactions. Comment on "Coupled disease-behavior dynamics on complex networks: A review" by Z. Wang et al.

Science.gov (United States)

Rosati, Dora P.; Molina, Chai; Earn, David J. D.

2015-12-01

Human behaviour and disease dynamics can greatly influence each other. In particular, people often engage in self-protective behaviours that affect epidemic patterns (e.g., vaccination, use of barrier precautions, isolation, etc.). Self-protective measures usually have a mitigating effect on an epidemic [16], but can in principle have negative impacts at the population level [12,15,18]. The structure of underlying social and biological contact networks can significantly influence the specific ways in which population-level effects are manifested. Using a different contact network in a disease dynamics model-keeping all else equal-can yield very different epidemic patterns. For example, it has been shown that when individuals imitate their neighbours' vaccination decisions with some probability, this can lead to herd immunity in some networks [9], yet for other networks it can preserve clusters of susceptible individuals that can drive further outbreaks of infectious disease [12].

Serviceability Assessment for Cascading Failures in Water Distribution Network under Seismic Scenario

Directory of Open Access Journals (Sweden)

Qing Shuang

2016-01-01

Full Text Available The stability of water service is a hot point in industrial production, public safety, and academic research. The paper establishes a service evaluation model for the water distribution network (WDN. The serviceability is measured in three aspects: (1 the functionality of structural components under disaster environment; (2 the recognition of cascading failure process; and (3 the calculation of system reliability. The node and edge failures in WDN are interrelated under seismic excitations. The cascading failure process is provided with the balance of water supply and demand. The matrix-based system reliability (MSR method is used to represent the system events and calculate the nonfailure probability. An example is used to illustrate the proposed method. The cascading failure processes with different node failures are simulated. The serviceability is analyzed. The critical node can be identified. The result shows that the aged network has a greater influence on the system service under seismic scenario. The maintenance could improve the antidisaster ability of WDN. Priority should be given to controlling the time between the initial failure and the first secondary failure, for taking postdisaster emergency measures within this time period can largely cut down the spread of cascade effect in the whole WDN.

The research on optimization of auto supply chain network robust model under macroeconomic fluctuations

International Nuclear Information System (INIS)

Guo, Chunxiang; Liu, Xiaoli; Jin, Maozhu; Lv, Zhihan

2016-01-01

Considering the uncertainty of the macroeconomic environment, the robust optimization method is studied for constructing and designing the automotive supply chain network, and based on the definition of robust solution a robust optimization model is built for integrated supply chain network design that consists of supplier selection problem and facility location–distribution problem. The tabu search algorithm is proposed for supply chain node configuration, analyzing the influence of the level of uncertainty on robust results, and by comparing the performance of supply chain network design through the stochastic programming model and robustness optimize model, on this basis, determining the rational layout of supply chain network under macroeconomic fluctuations. At last the contrastive test result validates that the performance of tabu search algorithm is outstanding on convergence and computational time. Meanwhile it is indicated that the robust optimization model can reduce investment risks effectively when it is applied to supply chain network design.

Assessing the role of contact tracing in a suspected H7N2 influenza A outbreak in humans in Wales

Directory of Open Access Journals (Sweden)

Salmon Roland

2010-05-01

Full Text Available Abstract Background The detailed analysis of an outbreak database has been undertaken to examine the role of contact tracing in controlling an outbreak of possible avian influenza in humans. The outbreak, initiating from the purchase of infected domestic poultry, occurred in North Wales during May and June 2007. During this outbreak, extensive contact tracing was carried out. Following contact tracing, cases and contacts believed to be at risk of infection were given treatment/prophylaxis. Methods We analyse the database of cases and their contacts identified for the purposes of contact tracing in relation to both the contact tracing burden and effectiveness. We investigate the distribution of numbers of contacts identified, and use network structure to explore the speed with which treatment/prophylaxis was made available and to estimate the risk of transmission in different settings. Results Fourteen cases of suspected H7N2 influenza A in humans were associated with a confirmed outbreak among poultry in May-June 2007. The contact tracing dataset consisted of 254 individuals (cases and contacts, of both poultry and humans who were linked through a network of social contacts. Of these, 102 individuals were given treatment or prophylaxis. Considerable differences between individuals' contact patterns were observed. Home and workplace encounters were more likely to result in transmission than encounters in other settings. After an initial delay, while the outbreak proceeded undetected, contact tracing rapidly caught up with the cases and was effective in reducing the time between onset of symptoms and treatment/prophylaxis. Conclusions Contact tracing was used to link together the individuals involved in this outbreak in a social network, allowing the identification of the most likely paths of transmission and the risks of different types of interactions to be assessed. The outbreak highlights the substantial time and cost involved in contact

Assessing the role of contact tracing in a suspected H7N2 influenza A outbreak in humans in Wales.

Science.gov (United States)

Eames, Ken T D; Webb, Cerian; Thomas, Kathrin; Smith, Josie; Salmon, Roland; Temple, J Mark F

2010-05-28

The detailed analysis of an outbreak database has been undertaken to examine the role of contact tracing in controlling an outbreak of possible avian influenza in humans. The outbreak, initiating from the purchase of infected domestic poultry, occurred in North Wales during May and June 2007. During this outbreak, extensive contact tracing was carried out. Following contact tracing, cases and contacts believed to be at risk of infection were given treatment/prophylaxis. We analyse the database of cases and their contacts identified for the purposes of contact tracing in relation to both the contact tracing burden and effectiveness. We investigate the distribution of numbers of contacts identified, and use network structure to explore the speed with which treatment/prophylaxis was made available and to estimate the risk of transmission in different settings. Fourteen cases of suspected H7N2 influenza A in humans were associated with a confirmed outbreak among poultry in May-June 2007. The contact tracing dataset consisted of 254 individuals (cases and contacts, of both poultry and humans) who were linked through a network of social contacts. Of these, 102 individuals were given treatment or prophylaxis. Considerable differences between individuals' contact patterns were observed. Home and workplace encounters were more likely to result in transmission than encounters in other settings. After an initial delay, while the outbreak proceeded undetected, contact tracing rapidly caught up with the cases and was effective in reducing the time between onset of symptoms and treatment/prophylaxis. Contact tracing was used to link together the individuals involved in this outbreak in a social network, allowing the identification of the most likely paths of transmission and the risks of different types of interactions to be assessed. The outbreak highlights the substantial time and cost involved in contact tracing, even for an outbreak affecting few individuals. However, when

Dynamic Multi-Rigid-Body Systems with Concurrent Distributed Contacts: Theory and Examples

International Nuclear Information System (INIS)

TRINKLE, JEFFREY C.; TZITZOURIS, J.A.; PANG, J.S.

2001-01-01

Consider a system of rigid bodies with multiple concurrent contacts. The multi-rigid-body contact problem is to predict the accelerations of the bodies and the normal friction loads acting at the contacts. This paper presents theoretical results for the multi-rigid-body contact problem under the assumptions that one or more contacts occur over locally planar, finite regions and that friction forces are consistent with the maximum work inequality. Existence and uniqueness results are presented for this problem under mild assumptions on the system inputs. In addition, the performance of two different time-stepping methods for integrating the dynamics are compared on two simple multi-body systems

THE ELECTROSTATIC CHARACTERISTICS OF LINEAR INSULATORS FOR CONTACT NETWORKS OF RAILWAYS

Directory of Open Access Journals (Sweden)

Ye. D. Kim

2009-03-01

Full Text Available On the base of numeric investigations on mathematical models of stationary electric field the basic electric performances of insulating suspensions from porcelain and polymeric insulators for contact nets of alternating and direct current are compared.

Animal transportation networks

Science.gov (United States)

Perna, Andrea; Latty, Tanya

2014-01-01

Many group-living animals construct transportation networks of trails, galleries and burrows by modifying the environment to facilitate faster, safer or more efficient movement. Animal transportation networks can have direct influences on the fitness of individuals, whereas the shape and structure of transportation networks can influence community dynamics by facilitating contacts between different individuals and species. In this review, we discuss three key areas in the study of animal transportation networks: the topological properties of networks, network morphogenesis and growth, and the behaviour of network users. We present a brief primer on elements of network theory, and then discuss the different ways in which animal groups deal with the fundamental trade-off between the competing network properties of travel efficiency, robustness and infrastructure cost. We consider how the behaviour of network users can impact network efficiency, and call for studies that integrate both network topology and user behaviour. We finish with a prospectus for future research. PMID:25165598

Core regulatory network motif underlies the ocellar complex patterning in Drosophila melanogaster

Science.gov (United States)

Aguilar-Hidalgo, D.; Lemos, M. C.; Córdoba, A.

2015-03-01

During organogenesis, developmental programs governed by Gene Regulatory Networks (GRN) define the functionality, size and shape of the different constituents of living organisms. Robustness, thus, is an essential characteristic that GRNs need to fulfill in order to maintain viability and reproducibility in a species. In the present work we analyze the robustness of the patterning for the ocellar complex formation in Drosophila melanogaster fly. We have systematically pruned the GRN that drives the development of this visual system to obtain the minimum pathway able to satisfy this pattern. We found that the mechanism underlying the patterning obeys to the dynamics of a 3-nodes network motif with a double negative feedback loop fed by a morphogenetic gradient that triggers the inhibition in a French flag problem fashion. A Boolean modeling of the GRN confirms robustness in the patterning mechanism showing the same result for different network complexity levels. Interestingly, the network provides a steady state solution in the interocellar part of the patterning and an oscillatory regime in the ocelli. This theoretical result predicts that the ocellar pattern may underlie oscillatory dynamics in its genetic regulation.

Amino acid empirical contact energy definitions for fold recognition in the space of contact maps

Directory of Open Access Journals (Sweden)

Fogolari Federico

2003-02-01

Full Text Available Abstract Background Contradicting evidence has been presented in the literature concerning the effectiveness of empirical contact energies for fold recognition. Empirical contact energies are calculated on the basis of information available from selected protein structures, with respect to a defined reference state, according to the quasi-chemical approximation. Protein-solvent interactions are estimated from residue solvent accessibility. Results In the approach presented here, contact energies are derived from the potential of mean force theory, several definitions of contact are examined and their performance in fold recognition is evaluated on sets of decoy structures. The best definition of contact is tested, on a more realistic scenario, on all predictions including sidechains accepted in the CASP4 experiment. In 30 out of 35 cases the native structure is correctly recognized and best predictions are usually found among the 10 lowest energy predictions. Conclusion The definition of contact based on van der Waals radii of alpha carbon and side chain heavy atoms is seen to perform better than other definitions involving only alpha carbons, only beta carbons, all heavy atoms or only backbone atoms. An important prerequisite for the applicability of the approach is that the protein structure under study should not exhibit anomalous solvent accessibility, compared to soluble proteins whose structure is deposited in the Protein Data Bank. The combined evaluation of a solvent accessibility parameter and contact energy allows for an effective gross screening of predictive models.

Modeling the Emergence of Contact Languages

Science.gov (United States)

Tria, Francesca; Servedio, Vito D.P.; Mufwene, Salikoko S.; Loreto, Vittorio

2015-01-01

Contact languages are born out of the non-trivial interaction of two (or more) parent languages. Nowadays, the enhanced possibility of mobility and communication allows for a strong mixing of languages and cultures, thus raising the issue of whether there are any pure languages or cultures that are unaffected by contact with others. As with bacteria or viruses in biological evolution, the evolution of languages is marked by horizontal transmission; but to date no reliable quantitative tools to investigate these phenomena have been available. An interesting and well documented example of contact language is the emergence of creole languages, which originated in the contacts of European colonists and slaves during the 17th and 18th centuries in exogenous plantation colonies of especially the Atlantic and Indian Ocean. Here, we focus on the emergence of creole languages to demonstrate a dynamical process that mimics the process of creole formation in American and Caribbean plantation ecologies. Inspired by the Naming Game (NG), our modeling scheme incorporates demographic information about the colonial population in the framework of a non-trivial interaction network including three populations: Europeans, Mulattos/Creoles, and Bozal slaves. We show how this sole information makes it possible to discriminate territories that produced modern creoles from those that did not, with a surprising accuracy. The generality of our approach provides valuable insights for further studies on the emergence of languages in contact ecologies as well as to test specific hypotheses about the peopling and the population structures of the relevant territories. We submit that these tools could be relevant to addressing problems related to contact phenomena in many cultural domains: e.g., emergence of dialects, language competition and hybridization, globalization phenomena. PMID:25875371

Designing container shipping network under changing demand and freight rates

Directory of Open Access Journals (Sweden)

C. Chen

2010-03-01

Full Text Available This paper focuses on the optimization of container shipping network and its operations under changing cargo demand and freight rates. The problem is formulated as a mixed integer non-linear programming problem (MINP with an objective of maximizing the average unit ship-slot profit at three stages using analytical methodology. The issues such as empty container repositioning, ship-slot allocating, ship sizing, and container configuration are simultaneously considered based on a series of the matrices of demand for a year. To solve the model, a bi-level genetic algorithm based method is proposed. Finally, numerical experiments are provided to illustrate the validity of the proposed model and algorithms. The obtained results show that the suggested model can provide a more realistic solution to the issues on the basis of changing demand and freight rates and arrange a more effective approach to the optimization of container shipping network structures and operations than does the model based on the average demand.

Converging models of schizophrenia - Network alterations of prefrontal cortex underlying cognitive impairments

Science.gov (United States)

Sakurai, Takeshi; Gamo, Nao J; Hikida, Takatoshi; Kim, Sun-Hong; Murai, Toshiya; Tomoda, Toshifumi; Sawa, Akira

2015-01-01

The prefrontal cortex (PFC) and its connections with other brain areas are crucial for cognitive function. Cognitive impairments are one of the core symptoms associated with schizophrenia, and manifest even before the onset of the disorder. Altered neural networks involving PFC contribute to cognitive impairments in schizophrenia. Both genetic and environmental risk factors affect the development of the local circuitry within PFC as well as development of broader brain networks, and make the system vulnerable to further insults during adolescence, leading to the onset of the disorder in young adulthood. Since spared cognitive functions correlate with functional outcome and prognosis, a better understanding of the mechanisms underlying cognitive impairments will have important implications for novel therapeutics for schizophrenia focusing on cognitive functions. Multidisciplinary approaches, from basic neuroscience to clinical studies, are required to link molecules, circuitry, networks, and behavioral phenotypes. Close interactions among such fields by sharing a common language on connectomes, behavioral readouts, and other concepts are crucial for this goal. PMID:26408506

Network interactions underlying mirror feedback in stroke: A dynamic causal modeling study

Directory of Open Access Journals (Sweden)

Soha Saleh

2017-01-01

Full Text Available Mirror visual feedback (MVF is potentially a powerful tool to facilitate recovery of disordered movement and stimulate activation of under-active brain areas due to stroke. The neural mechanisms underlying MVF have therefore been a focus of recent inquiry. Although it is known that sensorimotor areas can be activated via mirror feedback, the network interactions driving this effect remain unknown. The aim of the current study was to fill this gap by using dynamic causal modeling to test the interactions between regions in the frontal and parietal lobes that may be important for modulating the activation of the ipsilesional motor cortex during mirror visual feedback of unaffected hand movement in stroke patients. Our intent was to distinguish between two theoretical neural mechanisms that might mediate ipsilateral activation in response to mirror-feedback: transfer of information between bilateral motor cortices versus recruitment of regions comprising an action observation network which in turn modulate the motor cortex. In an event-related fMRI design, fourteen chronic stroke subjects performed goal-directed finger flexion movements with their unaffected hand while observing real-time visual feedback of the corresponding (veridical or opposite (mirror hand in virtual reality. Among 30 plausible network models that were tested, the winning model revealed significant mirror feedback-based modulation of the ipsilesional motor cortex arising from the contralesional parietal cortex, in a region along the rostral extent of the intraparietal sulcus. No winning model was identified for the veridical feedback condition. We discuss our findings in the context of supporting the latter hypothesis, that mirror feedback-based activation of motor cortex may be attributed to engagement of a contralateral (contralesional action observation network. These findings may have important implications for identifying putative cortical areas, which may be targeted with

Patch test results with fragrance markers of the baseline series - analysis of the European Surveillance System on Contact Allergies (ESSCA) network 2009-2012.

Science.gov (United States)

Frosch, Peter J; Duus Johansen, Jeanne; Schuttelaar, Marie-Louise A; Silvestre, Juan F; Sánchez-Pérez, Javier; Weisshaar, Elke; Uter, Wolfgang

2015-09-01

Contact allergy to fragrances is common, and impairs quality of life, particularly in young women. To provide current results on the prevalences of sensitization to fragrance allergens used as markers in the baseline series of most European countries. Data of patients consecutively patch tested between 2009 and 2012 in 12 European countries with fragrance allergens contained in the baseline series were collected by the European Surveillance System on Contact Allergies network and descriptively analysed. Four departments used the TRUE Test(®) system. The 'basic markers' were tested on 51 477 [fragrance mix II (FM II)] to 57 123 [Myroxylon pereirae, balsam of Peru] patients, and yielded positive reactions as follows: fragrance mix I 6.9%, Myroxylon pereirae 5.4%, FM II 3.8%, colophonium 2.6%, and hydroxyisohexyl 3-cyclohexene carboxaldehyde 1.7%, with some regional differences. Prevalences with TRUE Test(®) allergens were lower. Additional fragrances were tested on 3643 (trimethylbenzenepropanol) to 14 071 (oil of turpentine) patients, and yielded between 2.6% (Cananga odorata) and 0.7% (trimethylbenzenepropanol) positive reactions. Contact allergy to fragrances is common throughout Europe, with regional variation probably being explained by patch test technique, and differences in exposure and referral patterns. The current basic markers of fragrance sensitivity in the baseline series should be supplemented with additional fragrance allergens. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Role of copper oxides in contact killing of bacteria.

Science.gov (United States)

Hans, Michael; Erbe, Andreas; Mathews, Salima; Chen, Ying; Solioz, Marc; Mücklich, Frank

2013-12-31

The potential of metallic copper as an intrinsically antibacterial material is gaining increasing attention in the face of growing antibiotics resistance of bacteria. However, the mechanism of the so-called "contact killing" of bacteria by copper surfaces is poorly understood and requires further investigation. In particular, the influences of bacteria-metal interaction, media composition, and copper surface chemistry on contact killing are not fully understood. In this study, copper oxide formation on copper during standard antimicrobial testing was measured in situ by spectroscopic ellipsometry. In parallel, contact killing under these conditions was assessed with bacteria in phosphate buffered saline (PBS) or Tris-Cl. For comparison, defined Cu2O and CuO layers were thermally generated and characterized by grazing incidence X-ray diffraction. The antibacterial properties of these copper oxides were tested under the conditions used above. Finally, copper ion release was recorded for both buffer systems by inductively coupled plasma atomic absorption spectroscopy, and exposed copper samples were analyzed for topographical surface alterations. It was found that there was a fairly even growth of CuO under wet plating conditions, reaching 4-10 nm in 300 min, but no measurable Cu2O was formed during this time. CuO was found to significantly inhibit contact killing, compared to pure copper. In contrast, thermally generated Cu2O was essentially as effective in contact killing as pure copper. Copper ion release from the different surfaces roughly correlated with their antibacterial efficacy and was highest for pure copper, followed by Cu2O and CuO. Tris-Cl induced a 10-50-fold faster copper ion release compared to PBS. Since the Cu2O that primarily forms on copper under ambient conditions is as active in contact killing as pure copper, antimicrobial objects will retain their antimicrobial properties even after oxide formation.

Two classes of bipartite networks: nested biological and social systems.

Science.gov (United States)

Burgos, Enrique; Ceva, Horacio; Hernández, Laura; Perazzo, R P J; Devoto, Mariano; Medan, Diego

2008-10-01

Bipartite graphs have received some attention in the study of social networks and of biological mutualistic systems. A generalization of a previous model is presented, that evolves the topology of the graph in order to optimally account for a given contact preference rule between the two guilds of the network. As a result, social and biological graphs are classified as belonging to two clearly different classes. Projected graphs, linking the agents of only one guild, are obtained from the original bipartite graph. The corresponding evolution of its statistical properties is also studied. An example of a biological mutualistic network is analyzed in detail, and it is found that the model provides a very good fitting of all the main statistical features. The model also provides a proper qualitative description of the same features observed in social webs, suggesting the possible reasons underlying the difference in the organization of these two kinds of bipartite networks.

Human communication dynamics in digital footsteps: a study of the agreement between self-reported ties and email networks.

Directory of Open Access Journals (Sweden)

Stefan Wuchty

Full Text Available Digital communication data has created opportunities to advance the knowledge of human dynamics in many areas, including national security, behavioral health, and consumerism. While digital data uniquely captures the totality of a person's communication, past research consistently shows that a subset of contacts makes up a person's "social network" of unique resource providers. To address this gap, we analyzed the correspondence between self-reported social network data and email communication data with the objective of identifying the dynamics in e-communication that correlate with a person's perception of a significant network tie. First, we examined the predictive utility of three popular methods to derive social network data from email data based on volume and reciprocity of bilateral email exchanges. Second, we observed differences in the response dynamics along self-reported ties, allowing us to introduce and test a new method that incorporates time-resolved exchange data. Using a range of robustness checks for measurement and misreporting errors in self-report and email data, we find that the methods have similar predictive utility. Although e-communication has lowered communication costs with large numbers of persons, and potentially extended our number of, and reach to contacts, our case results suggest that underlying behavioral patterns indicative of friendship or professional contacts continue to operate in a classical fashion in email interactions.

Human communication dynamics in digital footsteps: a study of the agreement between self-reported ties and email networks.

Science.gov (United States)

Wuchty, Stefan; Uzzi, Brian

2011-01-01

Digital communication data has created opportunities to advance the knowledge of human dynamics in many areas, including national security, behavioral health, and consumerism. While digital data uniquely captures the totality of a person's communication, past research consistently shows that a subset of contacts makes up a person's "social network" of unique resource providers. To address this gap, we analyzed the correspondence between self-reported social network data and email communication data with the objective of identifying the dynamics in e-communication that correlate with a person's perception of a significant network tie. First, we examined the predictive utility of three popular methods to derive social network data from email data based on volume and reciprocity of bilateral email exchanges. Second, we observed differences in the response dynamics along self-reported ties, allowing us to introduce and test a new method that incorporates time-resolved exchange data. Using a range of robustness checks for measurement and misreporting errors in self-report and email data, we find that the methods have similar predictive utility. Although e-communication has lowered communication costs with large numbers of persons, and potentially extended our number of, and reach to contacts, our case results suggest that underlying behavioral patterns indicative of friendship or professional contacts continue to operate in a classical fashion in email interactions.

Improving the contact resistance at low force using gold coated carbon nanotube surfaces

Science.gov (United States)

McBride, J. W.; Yunus, E. M.; Spearing, S. M.

2010-04-01

Investigations to determine the electrical contact performance under repeated cycles at low force conditions for carbon-nanotube (CNT) coated surfaces were performed. The surfaces under investigation consisted of multi-walled CNT synthesized on a silicon substrate and coated with a gold film. These planar surfaces were mounted on the tip of a PZT actuator and contacted with a plated Au hemispherical probe. The dynamic applied force used was 1 mN. The contact resistance (Rc) of these surfaces was investigated with the applied force and with repeated loading cycles performed for stability testing. The surfaces were compared with a reference Au-Au contact under the same experimental conditions. This initial study shows the potential for the application of gold coated CNT surfaces as an interface in low force electrical contact applications.

Linear and non-linear simulation of joints contact surface using ...

African Journals Online (AJOL)

The joint modelling including non-linear effects needs accurate and precise study of their behaviors. When joints are under the dynamic loading, micro, macro- slip happens in contact surface which is non-linear reason of the joint contact surface. The non-linear effects of joint contact surface on total behavior of structure are ...

Development of a novel non-contact inspection technique to detect micro cracks under the surface of a glass substrate by thermal stress-induced light scattering method

Science.gov (United States)

Sakata, Yoshitaro; Terasaki, Nao; Nonaka, Kazuhiro

2017-05-01

Fine polishing techniques, such as a chemical mechanical polishing treatment, are important techniques in glass substrate manufacturing. However, these techniques may cause micro cracks under the surface of glass substrates because they used mechanical friction. A stress-induced light scattering method (SILSM), which was combined with light scattering method and mechanical stress effects, was proposed for inspecting surfaces to detect polishing-induced micro cracks. However, in the conventional SILSM, samples need to be loaded with physical contact, and the loading point is invisible in transparent materials. Here, we introduced a novel non-contact SILSM using a heating device. A glass substrate was heated first, and then the light scattering intensity of micro cracks was detected by a cooled charge-couple device camera during the natural cooling process. Results clearly showed during the decreasing surface temperature of a glass substrate, appropriate thermal stress is generated for detecting micro cracks by using the SILSM and light scattering intensity from micro cracks changes. We confirmed that non-contact thermal SILSM (T-SILSM) can detect micro cracks under the surface of transparent materials.

Investigation into the behaviour of bentonite in contact with magnetite and iron under the conditions of a final repository

International Nuclear Information System (INIS)

Mueller-Vonmoos, M.; Kahr, G.; Bucher, F.; Madsen, F.; Mayor, P.A.

1991-05-01

This report presents the results of investigations into how magnetite and iron affect the swelling behaviour of the Na-bentonite MX-80 and the Ca-bentonite Montigel. The experiments were conducted under conditions similar to those expected in a repository and covered cation exchange capacity, exchangeable cations and the swelling behaviour of the Na-bentonite MX-80 and the Ca-bentonite Montigel. Waste disposal is assumed to occur at a temperature of 80 o C under an anoxic atmosphere. In addition to this, the behaviour of trivalent iron in the interlayer space of montmorillonite was investigated. The investigations confirmed that contact between iron and bentonite under such conditions leads mainly to formation of magnetite and hydrogen. Montmorillonite does not take up iron by cation-exchange, either on contact with magnetite or with iron itself. The trivalent iron is unstable in the interlayer space of the montmorillonite and is exchanged mainly for aluminium; no change in the interlayer charge can be determined in such a case. It is therefore to be assumed that the aluminium is taken up from the edges of the clay particles into the interlayer space, but that no chlorite formation can be observed during this process. At 80 o C and 150 o C, the swelling pressures of the highly compacted bentonite-iron samples, related to the dry density of the bentonites, corresponded more or less to the swelling pressures of the untreated bentonites. The swelling pressure of the Fe(III)-bentonites was around 50% higher. It is assumed that this is mainly due to the high hydration energy of the iron and aluminium ions. 6 figs., 6 tabs., 13 refs

The Josephson effect in atomic contacts; Effect Josephson dans les contacts atomiques

Energy Technology Data Exchange (ETDEWEB)

Chauvin, M

2005-11-15

The Josephson effect appears when a weak-link establishes phase coherence between two superconductors. A unifying theory of this effect emerged in the 90's within the framework of mesoscopic physics. Based on two cornerstone concepts, conduction channels and Andreev reflection, it predicts the current-phase relation for the most basic weak-link: a single conduction channel of arbitrary transmission. This thesis illustrates this mesoscopic point of view with experiments on superconducting atomic size contacts. In particular, we have focused on the supercurrent peak around zero voltage, put into evidence the ac Josephson currents in a contact under constant bias voltage (Shapiro resonances and photon assisted multiple Andreev reflections), and performed direct measurements of the current-phase relation. (author)

Contact symmetries and Hamiltonian thermodynamics

International Nuclear Information System (INIS)

Bravetti, A.; Lopez-Monsalvo, C.S.; Nettel, F.

2015-01-01

It has been shown that contact geometry is the proper framework underlying classical thermodynamics and that thermodynamic fluctuations are captured by an additional metric structure related to Fisher’s Information Matrix. In this work we analyse several unaddressed aspects about the application of contact and metric geometry to thermodynamics. We consider here the Thermodynamic Phase Space and start by investigating the role of gauge transformations and Legendre symmetries for metric contact manifolds and their significance in thermodynamics. Then we present a novel mathematical characterization of first order phase transitions as equilibrium processes on the Thermodynamic Phase Space for which the Legendre symmetry is broken. Moreover, we use contact Hamiltonian dynamics to represent thermodynamic processes in a way that resembles the classical Hamiltonian formulation of conservative mechanics and we show that the relevant Hamiltonian coincides with the irreversible entropy production along thermodynamic processes. Therefore, we use such property to give a geometric definition of thermodynamically admissible fluctuations according to the Second Law of thermodynamics. Finally, we show that the length of a curve describing a thermodynamic process measures its entropy production

Diagnostic reasoning and underlying knowledge of students with preclinical patient contacts in PBL

NARCIS (Netherlands)

Diemers, Agnes D.; van de Wiel, Margje W. J.; Scherpbier, Albert J. J. A.; Baarveld, Frank; Dolmans, Diana H. J. M.

2015-01-01

CONTEXT: Medical experts have access to elaborate and integrated knowledge networks consisting of biomedical and clinical knowledge. These coherent knowledge networks enable them to generate more accurate diagnoses in a shorter time. However, students' knowledge networks are less organised and

Social networks and mental health in post-conflict Mitrovica, Kosova.

Science.gov (United States)

Nakayama, Risa; Koyanagi, Ai; Stickley, Andrew; Kondo, Tetsuo; Gilmour, Stuart; Arenliu, Aliriza; Shibuya, Kenji

2014-11-17

To investigate the relation between social networks and mental health in the post-conflict municipality of Mitrovica, Kosovo. Using a three-stage stratified sampling method, 1239 respondents aged 16 years or above were recruited in the Greater Mitrovica region. Social network depth was measured by the frequency of contacts with friends, relatives and strangers. Depression and anxiety were measured using the Hospital Anxiety and Depression Scale (HADS). Multivariate logistic regression was used to examine the association between social network depth and mental health. The analytical sample consisted of 993 respondents. The prevalence of depression (54.3%) and anxiety (64.4%) were extremely high. In multiple regression analysis, a lower depth of social network (contact with friends) was associated with higher levels of both depression and anxiety. This study has shown that only one variety of social network--contact with friends--was important in terms of mental health outcomes in a population living in an area heavily affected by conflict. This suggests that the relation between social networks and mental health may be complex in that the effects of different forms of social network on mental health are not uniform and may depend on the way social networks are operationalised and the particular context in which the relationship is examined.

Electro-thermal analysis of contact resistance

Science.gov (United States)

Pandey, Nitin; Jain, Ishant; Reddy, Sudhakar; Gulhane, Nitin P.

2018-05-01

Electro-Mechanical characterization over copper samples are performed at the macroscopic level to understand the dependence of electrical contact resistance and temperature on surface roughness and contact pressure. For two different surface roughness levels of samples, six levels of load are selected and varied to capture the bulk temperature rise and electrical contact resistance. Accordingly, the copper samples are modelled and analysed using COMSOLTM as a simulation package and the results are validated by the experiments. The interface temperature during simulation is obtained using Mikic-Elastic correlation and by directly entering experimental contact resistance value. The load values are varied and then reversed in a similar fashion to capture the hysteresis losses. The governing equations & assumptions underlying these models and their significance are examined & possible justification for the observed variations are discussed. Equivalent Greenwood model is also predicted by mapping the results of the experiment.

Effect of contact barrier on electron transport in graphene.

Science.gov (United States)

Zhou, Yang-Bo; Han, Bing-Hong; Liao, Zhi-Min; Zhao, Qing; Xu, Jun; Yu, Da-Peng

2010-01-14

The influence of the barrier between metal electrodes and graphene on the electrical properties was studied on a two-electrode device. A classical barrier model was used to analyze the current-voltage characteristics. Primary parameters including barrier height and effective resistance were achieved. The electron transport properties under magnetic field were further investigated. An abnormal peak-valley-peak shape of voltage-magnetoresistance curve was observed. The underlying mechanisms were discussed under the consideration of the important influence of the contact barrier. Our results indicate electrical properties of graphene based devices are sensitive to the contact interface.

Securing ad hoc wireless sensor networks under Byzantine attacks by implementing non-cryptographic method

Directory of Open Access Journals (Sweden)

Shabir Ahmad Sofi

2017-05-01

Full Text Available Ad Hoc wireless sensor network (WSN is a collection of nodes that do not need to rely on predefined infrastructure to keep the network connected. The level of security and performance are always somehow related to each other, therefore due to limited resources in WSN, cryptographic methods for securing the network against attacks is not feasible. Byzantine attacks disrupt the communication between nodes in the network without regard to its own resource consumption. This paper discusses the performance of cluster based WSN comparing LEACH with Advanced node based clusters under byzantine attacks. This paper also proposes an algorithm for detection and isolation of the compromised nodes to mitigate the attacks by non-cryptographic means. The throughput increases after using the algorithm for isolation of the malicious nodes, 33% in case of Gray Hole attack and 62% in case of Black Hole attack.

AcconPred: Predicting Solvent Accessibility and Contact Number Simultaneously by a Multitask Learning Framework under the Conditional Neural Fields Model

Directory of Open Access Journals (Sweden)

Jianzhu Ma

2015-01-01

Full Text Available Motivation. The solvent accessibility of protein residues is one of the driving forces of protein folding, while the contact number of protein residues limits the possibilities of protein conformations. The de novo prediction of these properties from protein sequence is important for the study of protein structure and function. Although these two properties are certainly related with each other, it is challenging to exploit this dependency for the prediction. Method. We present a method AcconPred for predicting solvent accessibility and contact number simultaneously, which is based on a shared weight multitask learning framework under the CNF (conditional neural fields model. The multitask learning framework on a collection of related tasks provides more accurate prediction than the framework trained only on a single task. The CNF method not only models the complex relationship between the input features and the predicted labels, but also exploits the interdependency among adjacent labels. Results. Trained on 5729 monomeric soluble globular protein datasets, AcconPred could reach 0.68 three-state accuracy for solvent accessibility and 0.75 correlation for contact number. Tested on the 105 CASP11 domain datasets for solvent accessibility, AcconPred could reach 0.64 accuracy, which outperforms existing methods.

The impact of awareness on epidemic spreading in networks.

Science.gov (United States)

Wu, Qingchu; Fu, Xinchu; Small, Michael; Xu, Xin-Jian

2012-03-01

We explore the impact of awareness on epidemic spreading through a population represented by a scale-free network. Using a network mean-field approach, a mathematical model for epidemic spreading with awareness reactions is proposed and analyzed. We focus on the role of three forms of awareness including local, global, and contact awareness. By theoretical analysis and simulation, we show that the global awareness cannot decrease the likelihood of an epidemic outbreak while both the local awareness and the contact awareness can. Also, the influence degree of the local awareness on disease dynamics is closely related with the contact awareness.

Emergence of amplitude death scenario in a network of oscillators under repulsive delay interaction

Energy Technology Data Exchange (ETDEWEB)

Bera, Bidesh K., E-mail: bideshbera18@gmail.com [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata 700108 (India); Hens, Chittaranjan, E-mail: chittaranjanhens@gmail.com [Department of Mathematics, Bar-Ilan University, Ramat Gan 52900 (Israel); Ghosh, Dibakar, E-mail: dibakar@isical.ac.in [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata 700108 (India)

2016-07-15

Highlights: • Amplitude death is observed using repulsive mean coupling. • Analytical conditions for amplitude death are derived. • Effect of asymmetry time delay coupling for death is discussed. - Abstract: We report the existence of amplitude death in a network of identical oscillators under repulsive mean coupling. Amplitude death appears in a globally coupled network of identical oscillators with instantaneous repulsive mean coupling only when the number of oscillators is more than two. We further investigate that, amplitude death may emerge even in two coupled oscillators as well as network of oscillators if we introduce delay time in the repulsive mean coupling. We have analytically derived the region of amplitude death island and find out how strength of delay controls the death regime in two coupled or a large network of coupled oscillators. We have verified our results on network of delayed Mackey–Glass systems where parameters are set in hyperchaotic regime. We have also tested our coupling approach in two paradigmatic limit cycle oscillators: Stuart–Landau and Van der Pol oscillators.

Emergence of amplitude death scenario in a network of oscillators under repulsive delay interaction

International Nuclear Information System (INIS)

Bera, Bidesh K.; Hens, Chittaranjan; Ghosh, Dibakar

2016-01-01

Highlights: • Amplitude death is observed using repulsive mean coupling. • Analytical conditions for amplitude death are derived. • Effect of asymmetry time delay coupling for death is discussed. - Abstract: We report the existence of amplitude death in a network of identical oscillators under repulsive mean coupling. Amplitude death appears in a globally coupled network of identical oscillators with instantaneous repulsive mean coupling only when the number of oscillators is more than two. We further investigate that, amplitude death may emerge even in two coupled oscillators as well as network of oscillators if we introduce delay time in the repulsive mean coupling. We have analytically derived the region of amplitude death island and find out how strength of delay controls the death regime in two coupled or a large network of coupled oscillators. We have verified our results on network of delayed Mackey–Glass systems where parameters are set in hyperchaotic regime. We have also tested our coupling approach in two paradigmatic limit cycle oscillators: Stuart–Landau and Van der Pol oscillators.

Epidemics on adaptive networks with geometric constraints

Science.gov (United States)

Shaw, Leah; Schwartz, Ira

2008-03-01

When a population is faced with an epidemic outbreak, individuals may modify their social behavior to avoid exposure to the disease. Recent work has considered models in which the contact network is rewired dynamically so that susceptibles avoid contact with infectives. We consider extensions in which the rewiring is subject to constraints that preserve key properties of the social network structure. Constraining to a fixed degree distribution destroys previously observed bistable behavior. The most effective rewiring strategy is found to depend on the spreading rate.

Preservation of atomically clean silicon surfaces in air by contact bonding

DEFF Research Database (Denmark)

Grey, Francois; Ljungberg, Karin

1997-01-01

When two hydrogen-passivated silicon surfaces are placed in contact under cleanroom conditions, a weak bond is formed. Cleaving this bond under ultrahigh vacuum (UHV) conditions, and observing the surfaces with low energy electron diffraction and scanning tunneling microscopy, we find that the or...... reconstruction from oxidation in air, Contact bonding opens the way to novel applications of reconstructed semiconductor surfaces, by preserving their atomic structure intact outside of a UHV chamber. (C) 1997 American Institute of Physics.......When two hydrogen-passivated silicon surfaces are placed in contact under cleanroom conditions, a weak bond is formed. Cleaving this bond under ultrahigh vacuum (UHV) conditions, and observing the surfaces with low energy electron diffraction and scanning tunneling microscopy, we find...... that the ordered atomic structure of the surfaces is protected from oxidation, even after the bonded samples have been in air for weeks. Further, we show that silicon surfaces that have been cleaned and hydrogen-passivated in UHV can be contacted in UHV in a similarly hermetic fashion, protecting the surface...

Molecular dynamics study of contact mechanics: contact area and interfacial separation from small to full contact

OpenAIRE

Yang, C.; Persson, B. N. J.

2007-01-01

We report a molecular dynamics study of the contact between a rigid solid with a randomly rough surface and an elastic block with a flat surface. We study the contact area and the interfacial separation from small contact (low load) to full contact (high load). For small load the contact area varies linearly with the load and the interfacial separation depends logarithmically on the load. For high load the contact area approaches to the nominal contact area (i.e., complete contact), and the i...

Connecting Land-Based Networks to Ships

Science.gov (United States)

2013-06-01

multipoint wireless broadband systems, and WiMAX networks were initially deployed for fixed and nomadic (portable) applications. These standards...CAPABILITIES OF SHIP-TO-SHORE COMMUNICATIONS A. US Navy Automated Digital Network System (ADNS) The U.S. Navy’s Automated Digital Network System (ADNS...submit digitally any necessary documents to the terminal operators, contact their logistics providers, access tidal information and receive

Optimal contact definition for reconstruction of Contact Maps

Directory of Open Access Journals (Sweden)

Stehr Henning

2010-05-01

Full Text Available Abstract Background Contact maps have been extensively used as a simplified representation of protein structures. They capture most important features of a protein's fold, being preferred by a number of researchers for the description and study of protein structures. Inspired by the model's simplicity many groups have dedicated a considerable amount of effort towards contact prediction as a proxy for protein structure prediction. However a contact map's biological interest is subject to the availability of reliable methods for the 3-dimensional reconstruction of the structure. Results We use an implementation of the well-known distance geometry protocol to build realistic protein 3-dimensional models from contact maps, performing an extensive exploration of many of the parameters involved in the reconstruction process. We try to address the questions: a to what accuracy does a contact map represent its corresponding 3D structure, b what is the best contact map representation with regard to reconstructability and c what is the effect of partial or inaccurate contact information on the 3D structure recovery. Our results suggest that contact maps derived from the application of a distance cutoff of 9 to 11Å around the Cβ atoms constitute the most accurate representation of the 3D structure. The reconstruction process does not provide a single solution to the problem but rather an ensemble of conformations that are within 2Å RMSD of the crystal structure and with lower values for the pairwise average ensemble RMSD. Interestingly it is still possible to recover a structure with partial contact information, although wrong contacts can lead to dramatic loss in reconstruction fidelity. Conclusions Thus contact maps represent a valid approximation to the structures with an accuracy comparable to that of experimental methods. The optimal contact definitions constitute key guidelines for methods based on contact maps such as structure prediction through

3D characterization of rolling contact fatigue crack networks

DEFF Research Database (Denmark)

Jessop, Casey; Ahlström, Johan; Hammar, Lars

2016-01-01

analysis method for geometrical reconstruction, and a 3D representation of the complex crack network was achieved. This was compared with measurements on cross-sections after repeated metallographic sectioning to determine the accuracy of prediction of the geometrical reconstruction. A second squat...... was investigated by X-ray tomography after extraction of a section of the rail head. A third squat was opened by careful cutting, which gave full access to the crack faces, and the topography was measured by stylus profilometry. The high-energy X-ray, 3D reconstruction method showed accurate main crack geometry...... to the crack face. However this time-consuming method requires destruction of the specimen investigated. The X-ray tomography revealed the 3D crack network including side branches in a 10×10×30mm3 sample, and provided topographic information without completely opening the squat. Topography measurements...

Network structure underlying resolution of conflicting non-verbal and verbal social information.

Science.gov (United States)

Watanabe, Takamitsu; Yahata, Noriaki; Kawakubo, Yuki; Inoue, Hideyuki; Takano, Yosuke; Iwashiro, Norichika; Natsubori, Tatsunobu; Takao, Hidemasa; Sasaki, Hiroki; Gonoi, Wataru; Murakami, Mizuho; Katsura, Masaki; Kunimatsu, Akira; Abe, Osamu; Kasai, Kiyoto; Yamasue, Hidenori

2014-06-01

Social judgments often require resolution of incongruity in communication contents. Although previous studies revealed that such conflict resolution recruits brain regions including the medial prefrontal cortex (mPFC) and posterior inferior frontal gyrus (pIFG), functional relationships and networks among these regions remain unclear. In this functional magnetic resonance imaging study, we investigated the functional dissociation and networks by measuring human brain activity during resolving incongruity between verbal and non-verbal emotional contents. First, we found that the conflict resolutions biased by the non-verbal contents activated the posterior dorsal mPFC (post-dmPFC), bilateral anterior insula (AI) and right dorsal pIFG, whereas the resolutions biased by the verbal contents activated the bilateral ventral pIFG. In contrast, the anterior dmPFC (ant-dmPFC), bilateral superior temporal sulcus and fusiform gyrus were commonly involved in both of the resolutions. Second, we found that the post-dmPFC and right ventral pIFG were hub regions in networks underlying the non-verbal- and verbal-content-biased resolutions, respectively. Finally, we revealed that these resolution-type-specific networks were bridged by the ant-dmPFC, which was recruited for the conflict resolutions earlier than the two hub regions. These findings suggest that, in social conflict resolutions, the ant-dmPFC selectively recruits one of the resolution-type-specific networks through its interaction with resolution-type-specific hub regions. © The Author (2013). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Deciding where to attend: Large-scale network mechanisms underlying attention and intention revealed by graph-theoretic analysis.

Science.gov (United States)

Liu, Yuelu; Hong, Xiangfei; Bengson, Jesse J; Kelley, Todd A; Ding, Mingzhou; Mangun, George R

2017-08-15

The neural mechanisms by which intentions are transformed into actions remain poorly understood. We investigated the network mechanisms underlying spontaneous voluntary decisions about where to focus visual-spatial attention (willed attention). Graph-theoretic analysis of two independent datasets revealed that regions activated during willed attention form a set of functionally-distinct networks corresponding to the frontoparietal network, the cingulo-opercular network, and the dorsal attention network. Contrasting willed attention with instructed attention (where attention is directed by external cues), we observed that the dorsal anterior cingulate cortex was allied with the dorsal attention network in instructed attention, but shifted connectivity during willed attention to interact with the cingulo-opercular network, which then mediated communications between the frontoparietal network and the dorsal attention network. Behaviorally, greater connectivity in network hubs, including the dorsolateral prefrontal cortex, the dorsal anterior cingulate cortex, and the inferior parietal lobule, was associated with faster reaction times. These results, shown to be consistent across the two independent datasets, uncover the dynamic organization of functionally-distinct networks engaged to support intentional acts. Copyright © 2017 Elsevier Inc. All rights reserved.

Old persons' contact with general practitioners in relation to health: a Danish population study

DEFF Research Database (Denmark)

Almind, G; Holstein, B E; Holst, E

1991-01-01

The study describes health, social situation, and contact with general practitioners in a random sample of non-institutionalized persons 70-95 years old in Denmark. There was a strong correlation between health and contact with general practitioners. A small group, 3% of the respondents, had...... no health problems, but had been in contact with a general practitioner within the previous month. This group was characterized by a strong social network and a high degree of life satisfaction. Another small group, including 3% of the respondents, had extensive health problems, but had nevertheless...

Social Networks and Sales Performance

Directory of Open Access Journals (Sweden)

Danny Pimentel Claro

2011-05-01

Full Text Available This paper argues that an informal network can itself be a basis for the increase in a sales manager’s performance. Informal networks create a structure that surpasses the formal hierarchical structure defined by the firm. We concentrated on the advice network and considered two different views of network structure that claim to have impact on performance. To explore this claim, we examined whether sales managers develop either a highly cohesive network structure (i.e. Coleman’s view or one containing structural holes (i.e. Burt’s view in order to achieve higher sales. We also investigated the matter of tie strength put forward by Granovetter in his seminal 1973 work. Census data was collected from about 500 personnel from an agricultural input retailer having 23 divisions. Estimates from a sample of 101 sales managers showed the importance of a highly cohesive structure (degree centrality for the three measures of sales manager’s performance. The strong ties have a positive impact on performance, suggesting the importance of building up strong bonds with network contacts. Sales managers’ age, time within the retailer and education also influence performance. These results imply that firms should stimulate contacts among personnel to spread technical and commercial information.

Analysis of Informationization Construction of Business Financial Management under the Network Economy

Science.gov (United States)

Dong, Yahui; Zhang, Pengwei; Li, Wei

To strengthen the informationization construction of the financial management has great significance to the achievement of business management informationization, and under the network economic environment, it is an important task of the financial management that how to conduct informationization construction of traditional financial management to provide true, reliable and complete financial information system for the business managers. This paper thoroughly researches the problem of financial information orientation management (FIOM) by taking the method of combining theory with practice. This paper puts forward the thinking method of financial information management, makes the new contents of E-finance. At last, this paper rebuilds the system of finance internal control from four aspects such as control of organization and management, system development control and safety control of network system.

Contact angle and local wetting at contact line.

Science.gov (United States)

Li, Ri; Shan, Yanguang

2012-11-06

This theoretical study was motivated by recent experiments and theoretical work that had suggested the dependence of the static contact angle on the local wetting at the triple-phase contact line. We revisit this topic because the static contact angle as a local wetting parameter is still not widely understood and clearly known. To further clarify the relationship of the static contact angle with wetting, two approaches are applied to derive a general equation for the static contact angle of a droplet on a composite surface composed of heterogeneous components. A global approach based on the free surface energy of a thermodynamic system containing the droplet and solid surface shows the static contact angle as a function of local surface chemistry and local wetting state at the contact line. A local approach, in which only local forces acting on the contact line are considered, results in the same equation. The fact that the local approach agrees with the global approach further demonstrates the static contact angle as a local wetting parameter. Additionally, the study also suggests that the wetting described by the Wenzel and Cassie equations is also the local wetting of the contact line rather than the global wetting of the droplet.

[Sport injuries in full contact and semi-contact karate].

Science.gov (United States)

Greier, K; Riechelmann, H; Ziemska, J

2014-03-01

Karate enjoys great popularity both in professional and recreational sports and can be classified into full, half and low contact styles. The aim of this study was the analysis of sports injuries in Kyokushinkai (full contact) and traditional Karate (semi-contact). In a retrospective study design, 215 active amateur karateka (114 full contact, 101 semi-contact) were interviewed by means of a standardised questionnaire regarding typical sport injuries during the last 36 months. Injuries were categorised into severity grade I (not requiring medical treatment), grade II (single medical treatment), grade III (several outpatient medical treatments) and grade IV (requiring hospitalisation). In total, 217 injuries were reported in detail. 125 injuries (58%) occurred in full contact and 92 (42%) in semi-contact karate. The time related injury rate of full contact karateka was 1.9/1000 h compared to 1.3/1000 h of semi-contact karateka (p injuries were musculoskeletal contusions (33% full contact, 20% semi-contact), followed by articular sprains with 19% and 16%. The lower extremity was affected twice as often in full contact (40%) as in semi-contact (20%) karate. Training injuries were reported by 80% of the full contact and 77% of the semi-contact karateka. Most injuries, both in training and competition, occurred in kumite. 75% of the reported injuries of full contact and 70% of semi-contact karateka were classified as low grade (I or II). The high rate of injuries during training and kumite (sparring) points to specific prevention goals. The emphasis should be put on proprioceptive training and consistent warm-up. In the actual competition the referees play a vital role regarding prevention. © Georg Thieme Verlag KG Stuttgart · New York.

NUMERICAL ANALYSIS OF THE STRESS-STRAIN STATE OF A ROPE STRAND WITH LINEAR CONTACT UNDER TENSION AND TORSION LOADING CONDITIONS

Directory of Open Access Journals (Sweden)

Evgenij Kalentev

2017-06-01

Full Text Available The paper presents the results of a numerical analysis of the stress-strain state of a rope strand with linear contact under tension and torsion loading conditions. Calculations are done using the ANSYS software package. Different approaches to calculation of the stress-strain state of ropes are reviewed, and their advantages and deficiencies are considered. The analysis of the obtained results leads us to the conclusion that the proposed method can be used in engineering calculations.

Elastomers in Combined Rolling-Sliding Contact; Wear and its Underlying Mechanisms

Science.gov (United States)

Rowe, Kyle Gene

Elastomeric materials, specifically rubbers, being both of a practical and scientific importance, have been the subjects of vast amounts of research spanning well over two centuries. There is currently a large effort by tire manufacturers to design new rubber compounds with lower rolling resistance, higher sliding friction, and reduced or predictable wear. At present, these efforts are primarily based on a few empirical rules and very costly trial and error testing; only a basic understanding of the mechanisms involved in the wear of elastomeric materials exists despite rigorous study. In general, the only well controlled experiments have been for simple loading and sliding schemes. The aim of this work is to characterize the tribological properties of a carbon black filled natural rubber sample. This work explores (1) its behavior in unidirectional sliding, (2) contact mechanics, (3) traction properties in combined rolling and sliding, (4) frictional heating response, and (5) wear. It was found that the friction coefficient of this material was dependent upon sliding velocity, contact pressure, and surface roughness. The high friction coefficients also lead to a bifurcation of the contact area into two different pressure regimes at sliding velocities greater than 10 mm/s . The traction response of this material in combined rolling and sliding exhibited similar behavior, being a function of the contact pressure, but not rolling velocity. The wear of this material was found to be linearly dependent upon the global slip condition and occurred preferentially on the sample. Investigations of the worn surface revealed that the most likely mechanism of wear is the degradation of surface material in a confined layer a few micrometers thick. A simple spring-mass model was developed to offer an explanation of localized wear. It was found that the coupling of system elements in the normal direction helped to shift the load from wearing elements to non-wearing ones. The

A Neural Network Model to Learn Multiple Tasks under Dynamic Environments

Science.gov (United States)

Tsumori, Kenji; Ozawa, Seiichi

When environments are dynamically changed for agents, the knowledge acquired in an environment might be useless in future. In such dynamic environments, agents should be able to not only acquire new knowledge but also modify old knowledge in learning. However, modifying all knowledge acquired before is not efficient because the knowledge once acquired may be useful again when similar environment reappears and some knowledge can be shared among different environments. To learn efficiently in such environments, we propose a neural network model that consists of the following modules: resource allocating network, long-term & short-term memory, and environment change detector. We evaluate the model under a class of dynamic environments where multiple function approximation tasks are sequentially given. The experimental results demonstrate that the proposed model possesses stable incremental learning, accurate environmental change detection, proper association and recall of old knowledge, and efficient knowledge transfer.

Social dilemmas in an online social network: The structure and evolution of cooperation

International Nuclear Information System (INIS)

Fu Feng; Chen Xiaojie; Liu Lianghuan; Wang Long

2007-01-01

We investigate two paradigms for studying the evolution of cooperation-Prisoner's Dilemma and Snowdrift game in an online friendship network, obtained from a social networking site. By structural analysis, it is revealed that the empirical social network has small-world and scale-free properties. Besides, it exhibits assortative mixing pattern. Then, we study the evolutionary version of the two types of games on it. It is found that cooperation is substantially promoted with small values of game matrix parameters in both games. Whereas the competent cooperators induced by the underlying network of contacts will be dramatically inhibited with increasing values of the game parameters. Further, we explore the role of assortativity in evolution of cooperation by random edge rewiring. We find that increasing amount of assortativity will to a certain extent diminish the cooperation level. We also show that connected large hubs are capable of maintaining cooperation. The evolution of cooperation on empirical networks is influenced by various network effects in a combined manner, compared with that on model networks. Our results can help understand the cooperative behaviors in human groups and society

Contact and Non-contact Measurements of Grinding Pins

Directory of Open Access Journals (Sweden)

Magdziak Marek

2015-01-01

Full Text Available The paper presents the results of contact and non-contact measurements of external profiles of selected grinding pins. The measurements were conducted in order to choose the appropriate measuring technique in the case of the considered measurement task. In the case of contact measurements the coordinate measuring machine ACCURA II was applied. The used coordinate measuring machine was equipped with the contact scanning probe VAST XT and the Calypso inspection software. Contact coordinate measurements were performed by using of different measurement strategies. The applied strategies included different scanning velocities and distances between measured points. Non-contact measurements were conducted by means of the tool presetter produced by the Mahr company. On the basis of gained results the guidelines concerning measurements of grinding pins were formulated. The measurements of analyzed grinding pins performed by means of the non-contact measuring system are characterized by higher reproducibility than the contact measurements. The low reproducibility of contact measurements may be connected with the inaccuracy of the selected coordinate measuring machine and the measuring probe, the measurement parameters and environmental conditions in the laboratory where the coordinate measuring machine is located. Moreover, the paper presents the possible application of results of conducted investigations. The results of non-contact measurements can be used in the simulation studies of grinding processes. The simulations may reduce the costs of machining processes.

Efficient local behavioral-change strategies to reduce the spread of epidemics in networks

Science.gov (United States)

Bu, Yilei; Gregory, Steve; Mills, Harriet L.

2013-10-01

It has recently become established that the spread of infectious diseases between humans is affected not only by the pathogen itself but also by changes in behavior as the population becomes aware of the epidemic, for example, social distancing. It is also well known that community structure (the existence of relatively densely connected groups of vertices) in contact networks influences the spread of disease. We propose a set of local strategies for social distancing, based on community structure, that can be employed in the event of an epidemic to reduce the epidemic size. Unlike most social distancing methods, ours do not require individuals to know the disease state (infected or susceptible, etc.) of others, and we do not make the unrealistic assumption that the structure of the entire contact network is known. Instead, the recommended behavior change is based only on an individual's local view of the network. Each individual avoids contact with a fraction of his/her contacts, using knowledge of his/her local network to decide which contacts should be avoided. If the behavior change occurs only when an individual becomes ill or aware of the disease, these strategies can substantially reduce epidemic size with a relatively small cost, measured by the number of contacts avoided.

Schizophrenia alters intra-network functional connectivity in the caudate for detecting speech under informational speech masking conditions.

Science.gov (United States)

Zheng, Yingjun; Wu, Chao; Li, Juanhua; Li, Ruikeng; Peng, Hongjun; She, Shenglin; Ning, Yuping; Li, Liang

2018-04-04

Speech recognition under noisy "cocktail-party" environments involves multiple perceptual/cognitive processes, including target detection, selective attention, irrelevant signal inhibition, sensory/working memory, and speech production. Compared to health listeners, people with schizophrenia are more vulnerable to masking stimuli and perform worse in speech recognition under speech-on-speech masking conditions. Although the schizophrenia-related speech-recognition impairment under "cocktail-party" conditions is associated with deficits of various perceptual/cognitive processes, it is crucial to know whether the brain substrates critically underlying speech detection against informational speech masking are impaired in people with schizophrenia. Using functional magnetic resonance imaging (fMRI), this study investigated differences between people with schizophrenia (n = 19, mean age = 33 ± 10 years) and their matched healthy controls (n = 15, mean age = 30 ± 9 years) in intra-network functional connectivity (FC) specifically associated with target-speech detection under speech-on-speech-masking conditions. The target-speech detection performance under the speech-on-speech-masking condition in participants with schizophrenia was significantly worse than that in matched healthy participants (healthy controls). Moreover, in healthy controls, but not participants with schizophrenia, the strength of intra-network FC within the bilateral caudate was positively correlated with the speech-detection performance under the speech-masking conditions. Compared to controls, patients showed altered spatial activity pattern and decreased intra-network FC in the caudate. In people with schizophrenia, the declined speech-detection performance under speech-on-speech masking conditions is associated with reduced intra-caudate functional connectivity, which normally contributes to detecting target speech against speech masking via its functions of suppressing masking-speech signals.

Mining Important Nodes in Directed Weighted Complex Networks

Directory of Open Access Journals (Sweden)

Yunyun Yang

2017-01-01

Full Text Available In complex networks, mining important nodes has been a matter of concern by scholars. In recent years, scholars have focused on mining important nodes in undirected unweighted complex networks. But most of the methods are not applicable to directed weighted complex networks. Therefore, this paper proposes a Two-Way-PageRank method based on PageRank for further discussion of mining important nodes in directed weighted complex networks. We have mainly considered the frequency of contact between nodes and the length of time of contact between nodes. We have considered the source of the nodes (in-degree and the whereabouts of the nodes (out-degree simultaneously. We have given node important performance indicators. Through numerical examples, we analyze the impact of variation of some parameters on node important performance indicators. Finally, the paper has verified the accuracy and validity of the method through empirical network data.

Contact: Releasing the news

Science.gov (United States)

Pinotti, Roberto

The problem of mass behavior after man's future contacts with other intelligences in the universe is not only a challenge for social scientists and political leaders all over the world, but also a cultural time bomb as well. In fact, since the impact of CETI (Contact with Extraterrestrial Intelligence) on human civilization, with its different cultures, might cause a serious socio-anthropological shock, a common and predetermined worldwide strategy is necessary in releasing the news after the contact, in order to keep possible manifestations of fear, panic and hysteria under control. An analysis of past studies in this field and of parallel historical situations as analogs suggests a definite "authority crisis" in the public as a direct consequence of an unexpected release of the news, involving a devastating "chain reaction" process (from both the psychological and sociological viewpoints) of anomie and maybe the collapse of today's society. The only way to prevent all this is to prepare the world's public opinion concerning contact before releasing the news, and to develop a long-term strategy through the combined efforts of scientists, political leaders, intelligence agencies and the mass media, in order to create the cultural conditions in which a confrontation with ETI won't affect mankind in a traumatic way. Definite roles and tasks in this multi-level model are suggested.

Adaptive neural network motion control for aircraft under uncertainty conditions

Science.gov (United States)

Efremov, A. V.; Tiaglik, M. S.; Tiumentsev, Yu V.

2018-02-01

We need to provide motion control of modern and advanced aircraft under diverse uncertainty conditions. This problem can be solved by using adaptive control laws. We carry out an analysis of the capabilities of these laws for such adaptive systems as MRAC (Model Reference Adaptive Control) and MPC (Model Predictive Control). In the case of a nonlinear control object, the most efficient solution to the adaptive control problem is the use of neural network technologies. These technologies are suitable for the development of both a control object model and a control law for the object. The approximate nature of the ANN model was taken into account by introducing additional compensating feedback into the control system. The capabilities of adaptive control laws under uncertainty in the source data are considered. We also conduct simulations to assess the contribution of adaptivity to the behavior of the system.

PERSON IN SOCIAL NETWORKS

Directory of Open Access Journals (Sweden)

Андрей Борисович Шалимов

2013-11-01

Full Text Available Purpose: Our scientific purpose is creation of practical model of person’s representation in social networks (Facebook, Twitter, Classmates. As user of social networks, person is made conditional not only upon its own identity, but also upon the information about himself, which he is ready to share with his friends in contact list. Goal-setting and practical activities for their achievement mean that you should apply force, it can completely eliminates systemic factors, the system of power relations, which overwhelms human being in social networks.Methodology: The reconstruction of the model of human in the popularity of social networksResults: There is descripton of practical model of person's representation in social networks, it includes the management of own identity and the audience (the list of contacts. When person manages own identity, he answers the question, «Whom I can dare to be?». Person perceives himself in social networks' being, he understands himself and his place in the world, he identifies.Managing the way in social media means that you answer the question «What I want to tell?». Person in social media looks at events in the field of culture, economy, politics, social relations through the prism of his own attitudes, he forms and formulates his own agenda and he is going to tell about himself through them.Practical implications: Everyday people’s life, practical activities, including marketing in social networks.DOI: http://dx.doi.org/10.12731/2218-7405-2013-9-51

Experimental study and artificial neural network modeling of tartrazine removal by photocatalytic process under solar light.

Science.gov (United States)

Sebti, Aicha; Souahi, Fatiha; Mohellebi, Faroudja; Igoud, Sadek

2017-07-01

This research focuses on the application of an artificial neural network (ANN) to predict the removal efficiency of tartrazine from simulated wastewater using a photocatalytic process under solar illumination. A program is developed in Matlab software to optimize the neural network architecture and select the suitable combination of training algorithm, activation function and hidden neurons number. The experimental results of a batch reactor operated under different conditions of pH, TiO 2 concentration, initial organic pollutant concentration and solar radiation intensity are used to train, validate and test the networks. While negligible mineralization is demonstrated, the experimental results show that under sunlight irradiation, 85% of tartrazine is removed after 300 min using only 0.3 g/L of TiO 2 powder. Therefore, irradiation time is prolonged and almost 66% of total organic carbon is reduced after 15 hours. ANN 5-8-1 with Bayesian regulation back-propagation algorithm and hyperbolic tangent sigmoid transfer function is found to be able to predict the response with high accuracy. In addition, the connection weights approach is used to assess the importance contribution of each input variable on the ANN model response. Among the five experimental parameters, the irradiation time has the greatest effect on the removal efficiency of tartrazine.

Social contact patterns relevant to the spread of respiratory infectious diseases in Hong Kong.

Science.gov (United States)

Leung, Kathy; Jit, Mark; Lau, Eric H Y; Wu, Joseph T

2017-08-11

The spread of many respiratory infections is determined by contact patterns between infectious and susceptible individuals in the population. There are no published data for quantifying social contact patterns relevant to the spread of respiratory infectious diseases in Hong Kong which is a hotspot for emerging infectious diseases due to its high population density and connectivity in the air transportation network. We adopted a commonly used diary-based design to conduct a social contact survey in Hong Kong in 2015/16 using both paper and online questionnaires. Participants using paper questionnaires reported more contacts and longer contact duration than those using online questionnaires. Participants reported 13 person-hours of contact and 8 contacts per day on average, which decreased over age but increased with household size, years of education and income level. Prolonged and frequent contacts, and contacts at home, school and work were more likely to involve physical contacts. Strong age-assortativity was observed in all age groups. We evaluated the characteristics of social contact patterns relevant to the spread of respiratory infectious diseases in Hong Kong. Our findings could help to improve the design of future social contact surveys, parameterize transmission models of respiratory infectious diseases, and inform intervention strategies based on model outputs.

Moving contact lines on vibrating surfaces

Science.gov (United States)

Solomenko, Zlatko; Spelt, Peter; Scott, Julian

2017-11-01

Large-scale simulations of flows with moving contact lines for realistic conditions generally requires a subgrid scale model (analyses based on matched asymptotics) to account for the unresolved part of the flow, given the large range of length scales involved near contact lines. Existing models for the interface shape in the contact-line region are primarily for steady flows on homogeneous substrates, with encouraging results in 3D simulations. Introduction of complexities would require further investigation of the contact-line region, however. Here we study flows with moving contact lines on planar substrates subject to vibrations, with applications in controlling wetting/dewetting. The challenge here is to determine the change in interface shape near contact lines due to vibrations. To develop further insight, 2D direct numerical simulations (wherein the flow is resolved down to an imposed slip length) have been performed to enable comparison with asymptotic theory, which is also developed further. Perspectives will also be presented on the final objective of the work, which is to develop a subgrid scale model that can be utilized in large-scale simulations. The authors gratefully acknowledge the ANR for financial support (ANR-15-CE08-0031) and the meso-centre FLMSN for use of computational resources. This work was Granted access to the HPC resources of CINES under the allocation A0012B06893 made by GENCI.

Percolation and epidemics in random clustered networks

Science.gov (United States)

Miller, Joel C.

2009-08-01

The social networks that infectious diseases spread along are typically clustered. Because of the close relation between percolation and epidemic spread, the behavior of percolation in such networks gives insight into infectious disease dynamics. A number of authors have studied percolation or epidemics in clustered networks, but the networks often contain preferential contacts in high degree nodes. We introduce a class of random clustered networks and a class of random unclustered networks with the same preferential mixing. Percolation in the clustered networks reduces the component sizes and increases the epidemic threshold compared to the unclustered networks.

Multiple dynamical time-scales in networks with hierarchically ...

Indian Academy of Sciences (India)

cists from resistor networks to polymer contact structure to spin interactions in disordered ... the intracellular signalling system to neuronal networks to ecological food ... tion of the key players can be used to develop drugs targeted specifically ...

Covalently crosslinked diels-alder polymer networks.

Energy Technology Data Exchange (ETDEWEB)

Bowman, Christopher (University of Colorado, Boulder, CO); Adzima, Brian J. (University of Colorado, Boulder, CO); Anderson, Benjamin John

2011-09-01

This project examines the utility of cycloaddition reactions for the synthesis of polymer networks. Cycloaddition reactions are desirable because they produce no unwanted side reactions or small molecules, allowing for the formation of high molecular weight species and glassy crosslinked networks. Both the Diels-Alder reaction and the copper-catalyzed azide-alkyne cycloaddition (CuAAC) were studied. Accomplishments include externally triggered healing of a thermoreversible covalent network via self-limited hysteresis heating, the creation of Diels-Alder based photoresists, and the successful photochemical catalysis of CuAAC as an alternative to the use of ascorbic acid for the generation of Cu(I) in click reactions. An analysis of the results reveals that these new methods offer the promise of efficiently creating robust, high molecular weight species and delicate three dimensional structures that incorporate chemical functionality in the patterned material. This work was performed under a Strategic Partnerships LDRD during FY10 and FY11 as part of a Sandia National Laboratories/University of Colorado-Boulder Excellence in Science and Engineering Fellowship awarded to Brian J. Adzima, a graduate student at UC-Boulder. Benjamin J. Anderson (Org. 1833) was the Sandia National Laboratories point-of-contact for this fellowship.

[Social Networks of Children with Mentally Ill Parents].

Science.gov (United States)

Stiawa, Maja; Kilian, Reinhold

2017-10-01

Social Networks of Children with Mentally Ill Parents Mental illness of parents can be a load situation for children. Supporting social relations might be an important source in such a situation. Social relations can be shown by social network analysis. Studies about social networks and mental health indicate differences regarding structure and potential for support when compared with social networks of healthy individuals. If and how mental illness of parents has an impact on their children's network is widely unknown. This systematic review shows methods and results of studies about social networks of children with mentally ill parents. By systematic search in electronic databases as well as manual search, two studies were found who met the target criteria. Both studies were conducted in the USA. Results of studies indicate that parental mental illness affects the state of mental health and social networks of children. Symptomatology of children changed due to perceived social support of network contacts. Impact of social support and strong network contacts seems to depend on age of children and the family situation. That's why support offers should be adapt to children's age. Focusing on social networks as potential resource for support and needs of the family affected seems appropriate during treatment.

An analysis pipeline for the inference of protein-protein interaction networks

Energy Technology Data Exchange (ETDEWEB)

Taylor, Ronald C.; Singhal, Mudita; Daly, Don S.; Gilmore, Jason M.; Cannon, William R.; Domico, Kelly O.; White, Amanda M.; Auberry, Deanna L.; Auberry, Kenneth J.; Hooker, Brian S.; Hurst, G. B.; McDermott, Jason E.; McDonald, W. H.; Pelletier, Dale A.; Schmoyer, Denise A.; Wiley, H. S.