scholarly journals Disentangling network topology and pathogen spread

2021 ◽  
Author(s):  
Maria Perez-Ortiz ◽  
Petru Manescu ◽  
Fabio Caccioli ◽  
Delmiro Fernandez-Reyes ◽  
Parashkev Nachev ◽  
...  
Keyword(s):  
Network Topology ◽  
Large Scale ◽  
Social Contact ◽  
Small World ◽  
Pathogen Transmission ◽  
Stochastic Simulations ◽  
Equal Weight ◽  
Topological Features ◽  
Network Metrics ◽  
The Impact

How do we best constrain social interactions to prevent the transmission of communicable respiratory diseases? Indiscriminate suppression, the currently accepted answer, is both unsustainable long term and implausibly presupposes all interactions to carry equal weight. Transmission within a social network is determined by the topology of its graphical structure, of which the number of interactions is only one aspect. Here we deploy large-scale numerical simulations to quantify the impact on pathogen transmission of a set of topological features covering the parameter space of realistic possibility. We first test through a series of stochastic simulations the differences in the spread of disease on several classes of network geometry (including highly skewed networks and small world). We then aim to characterise the spread based on the characteristics of the network topology using regression analysis, highlighting some of the network metrics that influence the spread the most. For this, we build a dataset composed of more than 9000 social networks and 30 topological network metrics. We find that pathogen spread is optimally reduced by limiting specific kinds of social contact -- unfamiliar and long range -- rather than their global number. Our results compel a revaluation of social interventions in communicable diseases, and the optimal approach to crafting them.

scholarly journals Organization of Areal Connectivity in the Monkey Frontoparietal Network

2020 ◽  
Author(s):  
Bryan D. Conklin
Keyword(s):  
Cognitive Functions ◽  
Large Scale ◽  
Small World ◽  
Connectivity Matrix ◽  
Anatomical Connectivity ◽  
Optimal Arrangement ◽  
Frontoparietal Network ◽  
Simultaneous Integration ◽  
Single Scale ◽  
The Impact

AbstractAnatomical connectivity between cortical areas condition the set of observable functional activity in a neural network. The large-scale cortical monkey frontoparietal network (FPN) has been shown to facilitate complex cognitive functions. However, the organization of anatomical connectivity between areas in the FPN supporting such function is unknown. Here, a new connectivity matrix is proposed which shows the FPN utilizes a small-world architecture with an over-reliance on the M9 dynamical relay 3-node motif and degree distributions which can be characterized as single scale. The FPN uses its small-world architecture to achieve the kind of simultaneous integration and specialization of function which cognitive functions like attention and working memory require. Contrary to many real-world networks, the in and out single scale degree distributions illustrate the relatively homogeneous connectivity of each area in the FPN, suggesting an absence of hubs. Crucially, the M9 dynamical relay motif is the optimal arrangement for previously reported near-zero and non-zero phase synchrony to propagate through the network, serving as a candidate topological mechanism. These results signify the impact of the organization of anatomical connectivity in the FPN. They can serve as a benchmark to be used in the network-level treatment of neurological disorders where the types of cognition the FPN supports are impaired. Additionally, they can inform future neuromorphic circuit designs which aim to perform aspects of cognition.

scholarly journals Close contact infection dynamics over time: insights from a second large-scale social contact survey in Flanders, Belgium, in 2010-2011

2020 ◽  
Author(s):  
Thang Van Hoang ◽  
Pietro Coletti ◽  
Yimer Wasihun Kiffe ◽  
Kim Van Kerckhove ◽  
Sarah Vercruysse ◽  
...  
Keyword(s):  
Large Scale ◽  
Close Contact ◽  
Social Contact ◽  
Contact Rates ◽  
Contact Patterns ◽  
Time Period ◽  
Social Mixing ◽  
Mixing Patterns ◽  
Contact Survey ◽  
The Impact

AbstractBackgroundIn 2010-2011, we conducted a social contact survey in Flanders, Belgium, aimed at improving and extending the design of the first social contact survey conducted in Belgium in 2006. This second social contact survey aimed to enable, for the first time, the estimation of social mixing patterns for an age range of 0 to 99 years and the investigation of whether contact rates remain stable over this 5-year time period.MethodsDifferent data mining techniques are used to explore the data, and the age-specific number of social contacts and the age-specific contact rates are modelled using a GAMLSS model. We compare different matrices using assortativeness measures. The relative change in the basic reproduction number (R0) and the ratio of relative incidences with 95% bootstrap confidence intervals (BCI) are employed to investigate and quantify the impact on epidemic spread due to differences in gender, day of the week, holiday vs. regular periods and changes in mixing patterns over the 5-year time gap between the 2006 and 2010-2011 surveys. Finally, we compare the fit of the contact matrices in 2006 and 2010-2011 to Varicella serological data.ResultsAll estimated contact patterns featured strong homophily in age and gender, especially for small children and adolescents. A 30% (95% BCI [17%; 37%] ) and 29% (95% BCI [14%; 40%] ) reduction in R0 was observed for weekend versus weekdays and for holiday versus regular periods, respectively. Significantly more interactions between people aged 60+ years and their grandchildren were observed on holiday and weekend days than on regular weekdays. Comparing contact patterns using different methods did not show any substantial differences over the 5-year time period under study.ConclusionsThe second social contact survey in Flanders, Belgium, endorses the findings of its 2006 predecessor and adds important information on the social mixing patterns of people older than 60 years of age. Based on this analysis, the mixing patterns of people older than 60 years exhibit considerable heterogeneity, and overall, the comparison of the two surveys shows that social contact rates can be assumed stable in Flanders over a time span of 5 years.

scholarly journals Predicting social and health vulnerability to floods in Bangladesh

2021 ◽  
Vol 21 (6) ◽  
pp. 1807-1823
Author(s):  
Donghoon Lee ◽  
Hassan Ahmadul ◽  
Jonathan Patz ◽  
Paul Block
Keyword(s):  
Disaster Management ◽  
Large Scale ◽  
Management Practices ◽  
Principal Component ◽  
Social Health ◽  
Equal Weight ◽  
Coping Capacity ◽  
Health Vulnerability ◽  
And Coping ◽  
The Impact

Abstract. Floods are the most common and damaging natural disaster in Bangladesh, and the effects of floods on public health have increased significantly in recent decades, particularly among lower socioeconomic populations. Assessments of social vulnerability on flood-induced health outcomes typically focus on local to regional scales; a notable gap remains in comprehensive, large-scale assessments that may foster disaster management practices. In this study, socioeconomic, health, and coping capacity vulnerability and composite social-health vulnerability are assessed using both equal-weight and principal-component approaches using 26 indicators across Bangladesh. Results indicate that vulnerable zones exist in the northwest riverine areas, northeast floodplains, and southwest region, potentially affecting 42 million people (26 % of the total population). Subsequently, the vulnerability measures are linked to flood forecast and satellite inundation information to evaluate their potential for predicting actual flood impact indices (distress, damage, disruption, and health) based on the immense August 2017 flood event. Overall, the forecast-based equally weighted vulnerability measures perform best. Specifically, socioeconomic and coping capacity vulnerability measures strongly align with the distress, disruption, and health impact records observed. Additionally, the forecast-based composite social-health vulnerability index also correlates well with the impact indices, illustrating its utility in identifying predominantly vulnerable regions. These findings suggest the benefits and practicality of this approach to assess both thematic and comprehensive spatial vulnerabilities, with the potential to support targeted and coordinated public disaster management and health practices.

scholarly journals Augmenting contact matrices with time-use data for fine-grained intervention modelling of disease dynamics: A modelling analysis

2021 ◽  
pp. 096228022110370
Author(s):  
Edwin van Leeuwen ◽  
Frank Sandmann ◽  
Keyword(s):  
Public Health ◽  
Time Use ◽  
Large Scale ◽  
Leisure Activities ◽  
Public Health Intervention ◽  
Social Contact ◽  
Daily Activities ◽  
Transmission Model ◽  
Fine Grained ◽  
The Impact

Social distancing is an important public health intervention to reduce or interrupt the sustained community transmission of emerging infectious pathogens, such as severe acute respiratory syndrome-coronavirus-2 during the coronavirus disease 2019 pandemic. Contact matrices are typically used when evaluating such public health interventions to account for the heterogeneity in social mixing of individuals, but the surveys used to obtain the number of contacts often lack detailed information on the time individuals spend on daily activities. The present work addresses this problem by combining the large-scale empirical data of a social contact survey and a time-use survey to estimate contact matrices by age group (0--15, 16--24, 25–44, 45–64, 65+ years) and daily activity (work, schooling, transportation, and four leisure activities: social visits, bar/cafe/restaurant visits, park visits, and non-essential shopping). This augmentation allows exploring the impact of fewer contacts when individuals reduce the time they spend on selected daily activities as well as when lifting such restrictions again. For illustration, the derived matrices were then applied to an age-structured dynamic-transmission model of coronavirus disease 2019. Findings show how contact matrices can be successfully augmented with time-use data to inform the relative reductions in contacts by activity, which allows for more fine-grained mixing patterns and infectious disease modelling.

scholarly journals Effects of network topology on the performance of consensus and distributed learning of SVMs using ADMM

2021 ◽  
Vol 7 ◽  
pp. e397
Author(s):  
Shirin Tavara ◽  
Alexander Schliep
Keyword(s):  
Network Topology ◽  
Large Scale ◽  
Learning Problems ◽  
Support Vector ◽  
Spectral Gaps ◽  
Distributed Framework ◽  
Alternating Direction ◽  
Communication Time ◽  
Network Topologies ◽  
The Impact

The Alternating Direction Method of Multipliers (ADMM) is a popular and promising distributed framework for solving large-scale machine learning problems. We consider decentralized consensus-based ADMM in which nodes may only communicate with one-hop neighbors. This may cause slow convergence. We investigate the impact of network topology on the performance of an ADMM-based learning of Support Vector Machine using expander, and mean-degree graphs, and additionally some of the common modern network topologies. In particular, we investigate to which degree the expansion property of the network influences the convergence in terms of iterations, training and communication time. We furthermore suggest which topology is preferable. Additionally, we provide an implementation that makes these theoretical advances easily available. The results show that the performance of decentralized ADMM-based learning of SVMs in terms of convergence is improved using graphs with large spectral gaps, higher and homogeneous degrees.

scholarly journals The impact of COVID-19 control measures on social contacts and transmission in Kenyan informal settlements

BMC Medicine ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Matthew Quaife ◽  
◽  
Kevin van Zandvoort ◽  
Amy Gimma ◽  
Kashvi Shah ◽  
...  
Keyword(s):  
Food Security ◽  
Social Contact ◽  
Informal Settlements ◽  
Pathogen Transmission ◽  
Control Measures ◽  
Respiratory Pathogen ◽  
African Countries ◽  
Contact Patterns ◽  
And Control ◽  
The Impact

Abstract Background Many low- and middle-income countries have implemented control measures against coronavirus disease 2019 (COVID-19). However, it is not clear to what extent these measures explain the low numbers of recorded COVID-19 cases and deaths in Africa. One of the main aims of control measures is to reduce respiratory pathogen transmission through direct contact with others. In this study, we collect contact data from residents of informal settlements around Nairobi, Kenya, to assess if control measures have changed contact patterns, and estimate the impact of changes on the basic reproduction number (R0). Methods We conducted a social contact survey with 213 residents of five informal settlements around Nairobi in early May 2020, 4 weeks after the Kenyan government introduced enhanced physical distancing measures and a curfew between 7 pm and 5 am. Respondents were asked to report all direct physical and non-physical contacts made the previous day, alongside a questionnaire asking about the social and economic impact of COVID-19 and control measures. We examined contact patterns by demographic factors, including socioeconomic status. We described the impact of COVID-19 and control measures on income and food security. We compared contact patterns during control measures to patterns from non-pandemic periods to estimate the change in R0. Results We estimate that control measures reduced physical contacts by 62% and non-physical contacts by either 63% or 67%, depending on the pre-COVID-19 comparison matrix used. Masks were worn by at least one person in 92% of contacts. Respondents in the poorest socioeconomic quintile reported 1.5 times more contacts than those in the richest. Eighty-six percent of respondents reported a total or partial loss of income due to COVID-19, and 74% reported eating less or skipping meals due to having too little money for food. Conclusion COVID-19 control measures have had a large impact on direct contacts and therefore transmission, but have also caused considerable economic and food insecurity. Reductions in R0 are consistent with the comparatively low epidemic growth in Kenya and other sub-Saharan African countries that implemented similar, early control measures. However, negative and inequitable impacts on economic and food security may mean control measures are not sustainable in the longer term.

scholarly journals On the impact of network size and average degree on the robustness of centrality measures

2020 ◽  
pp. 1-22
Author(s):  
Christoph Martin ◽  
Peter Niemeyer
Keyword(s):  
Network Topology ◽  
Measurement Errors ◽  
Network Size ◽  
Average Degree ◽  
Centrality Measures ◽  
Central Node ◽  
Free Network ◽  
Common Concept ◽  
Network Metrics ◽  
The Impact

Abstract Measurement errors are omnipresent in network data. Most studies observe an erroneous network instead of the desired error-free network. It is well known that such errors can have a severe impact on network metrics, especially on centrality measures: a central node in the observed network might be less central in the underlying, error-free network. The robustness is a common concept to measure these effects. Studies have shown that the robustness primarily depends on the centrality measure, the type of error (e.g., missing edges or missing nodes), and the network topology (e.g., tree-like, core-periphery). Previous findings regarding the influence of network size on the robustness are, however, inconclusive. We present empirical evidence and analytical arguments indicating that there exist arbitrary large robust and non-robust networks and that the average degree is well suited to explain the robustness. We demonstrate that networks with a higher average degree are often more robust. For the degree centrality and Erdős–Rényi (ER) graphs, we present explicit formulas for the computation of the robustness, mainly based on the joint distribution of node degrees and degree changes which allow us to analyze the robustness for ER graphs with a constant average degree or increasing average degree.

scholarly journals Predicting social and health vulnerability to floods in Bangladesh

2020 ◽  
Author(s):  
Donghoon Lee ◽  
Hassan Ahmadul ◽  
Jonathan Patz ◽  
Paul Block
Keyword(s):  
Disaster Management ◽  
Large Scale ◽  
Management Practices ◽  
Principal Component ◽  
Social Health ◽  
Equal Weight ◽  
Coping Capacity ◽  
Health Vulnerability ◽  
And Coping ◽  
The Impact

Abstract. Floods are the most common and damaging natural disaster in Bangladesh, and the effects of floods on public health have increased significantly in recent decades, particularly among lower socio-economic populations. Assessments of social vulnerability on flood-induced health outcomes typically focus on local to regional scales; a notable gap remains in comprehensive, large-scale assessments that may foster disaster management practices. In this study, socio-economic, health, and coping capacity vulnerability and composite social-health vulnerability are assessed using both equal-weight and principal component approaches using 26 indicators across Bangladesh. Results indicate that vulnerable zones exist in the northwest riverine areas, northeast floodplains, and southwest region, potentially affecting 42 million people (26 % of total population). Subsequently, the vulnerability measures are linked to flood forecast and satellite inundation information to evaluate their potential for predicting actual flood impact indices (distress, damage, disruption, and health) based on the immense August 2017 flood event. Overall, the forecast-based equally weighted vulnerability measures perform best. Specifically, socio-economic and coping capacity vulnerability measures strongly align with the distress, disruption, and health impacts records observed. Additionally, the forecast-based composite social-health vulnerability index also correlates well with the impact indices, illustrating its utility in identifying predominantly vulnerable regions. These findings suggest the benefits and practicality of this approach to assess both thematic and comprehensive spatial vulnerabilities, with the potential to support targeted and coordinated public disaster management and health practices.

scholarly journals Within and between classroom transmission patterns of seasonal influenza and implications for pandemic management strategies at schools

2021 ◽  
Author(s):  
Akira Endo ◽  
Mitsuo Uchida ◽  
Yang Liu ◽  
Katherine Atkins ◽  
Adam Kucharski ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Large Scale ◽  
Seasonal Influenza ◽  
Management Strategies ◽  
Social Contact ◽  
Screening Tests ◽  
Initial Growth ◽  
Precautionary Measures ◽  
Reduced Class Sizes ◽  
The Impact

Abstract Schools can play a central role in driving infectious disease transmission. Strategies for safe operation of schools during pandemics therefore need to carefully consider both the efficiency of measures for infection control and the impact on children through lost face-to face schooling time. Heterogeneous social contact patterns associated with the social structures of schools (i.e. classes/grades) are likely to influence the within-school transmission dynamics; however, empirical evidence on the fine-scale transmission patterns between students has been limited. Using a mathematical model, we analysed a large-scale dataset of seasonal influenza outbreaks in Matsumoto city, Japan to infer social interactions within and between classes/grades from observed transmission patterns. The overall within-school reproduction number, which determines the initial growth of cases and the risk of sustained transmission, was only minimally associated with class sizes and the number of classes per grade. We then used these patterns in a model parameterised separately to COVID-19 and pandemic influenza, and simulated school outbreaks under multiple strategies for minimising the risk of within-school transmission. Simulations suggested that with such transmission patterns, interventions changing class structures (e.g. reduced class sizes) may not be effective in reducing the risk of major school outbreaks upon introduction of a case and that other precautionary measures (e.g. screening and isolation) need to be employed. Class-level closures in response to detection of a case were suggested to be effective in reducing the size of an outbreak when regular screening tests for students are not available.

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