594 results on '"Mixing patterns"'
Search Results
2. Exploring human mixing patterns based on time use and social contact data and their implications for infectious disease transmission models
- Author
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Thang Van Hoang, Lander Willem, Pietro Coletti, Kim Van Kerckhove, Joeri Minnen, Philippe Beutels, and Niel Hens
- Subjects
Infectious disease dynamics ,Mixing patterns ,Exposure matrices ,Spatial dynamics ,Time use ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background The increasing availability of data on social contact patterns and time use provides invaluable information for studying transmission dynamics of infectious diseases. Social contact data provide information on the interaction of people in a population whereas the value of time use data lies in the quantification of exposure patterns. Both have been used as proxies for transmission risks within in a population and the combination of both sources has led to investigate which contacts are more suitable to describe these transmission risks. Methods We used social contact and time use data from 1707 participants from a survey conducted in Flanders, Belgium in 2010–2011. We calculated weighted exposure time and social contact matrices to analyze age- and gender-specific mixing patterns and to quantify behavioral changes by distance from home. We compared the value of both separate and combined data sources for explaining seroprevalence and incidence data on parvovirus-B19, Varicella-Zoster virus (VZV) and influenza like illnesses (ILI), respectively. Results Assortative mixing and inter-generational interaction is more pronounced in the exposure matrix due to the high proportion of time spent at home. This pattern is less pronounced in the social contact matrix, which is more impacted by the reported contacts at school and work. The average number of contacts declined with distance. On the individual-level, we observed an increase in the number of contacts and the transmission potential by distance when travelling. We found that both social contact data and time use data provide a good match with the seroprevalence and incidence data at hand. When comparing the use of different combinations of both data sources, we found that the social contact matrix based on close contacts of at least 4 h appeared to be the best proxy for parvovirus-B19 transmission. Social contacts and exposure time were both on their own able to explain VZV seroprevalence data though combining both scored best. Compared with the contact approach, the time use approach provided the better fit to the ILI incidence data. Conclusions Our work emphasises the common and complementary value of time use and social contact data for analysing mixing behavior and analysing infectious disease transmission. We derived spatial, temporal, age-, gender- and distance-specific mixing patterns, which are informative for future modelling studies.
- Published
- 2022
- Full Text
- View/download PDF
3. Exploring human mixing patterns based on time use and social contact data and their implications for infectious disease transmission models.
- Author
-
Hoang, Thang Van, Willem, Lander, Coletti, Pietro, Van Kerckhove, Kim, Minnen, Joeri, Beutels, Philippe, and Hens, Niel
- Subjects
- *
SOCIAL contact , *INFECTIOUS disease transmission , *SOCIAL interaction , *TIME management , *VARICELLA-zoster virus - Abstract
Background: The increasing availability of data on social contact patterns and time use provides invaluable information for studying transmission dynamics of infectious diseases. Social contact data provide information on the interaction of people in a population whereas the value of time use data lies in the quantification of exposure patterns. Both have been used as proxies for transmission risks within in a population and the combination of both sources has led to investigate which contacts are more suitable to describe these transmission risks. Methods: We used social contact and time use data from 1707 participants from a survey conducted in Flanders, Belgium in 2010–2011. We calculated weighted exposure time and social contact matrices to analyze age- and gender-specific mixing patterns and to quantify behavioral changes by distance from home. We compared the value of both separate and combined data sources for explaining seroprevalence and incidence data on parvovirus-B19, Varicella-Zoster virus (VZV) and influenza like illnesses (ILI), respectively. Results: Assortative mixing and inter-generational interaction is more pronounced in the exposure matrix due to the high proportion of time spent at home. This pattern is less pronounced in the social contact matrix, which is more impacted by the reported contacts at school and work. The average number of contacts declined with distance. On the individual-level, we observed an increase in the number of contacts and the transmission potential by distance when travelling. We found that both social contact data and time use data provide a good match with the seroprevalence and incidence data at hand. When comparing the use of different combinations of both data sources, we found that the social contact matrix based on close contacts of at least 4 h appeared to be the best proxy for parvovirus-B19 transmission. Social contacts and exposure time were both on their own able to explain VZV seroprevalence data though combining both scored best. Compared with the contact approach, the time use approach provided the better fit to the ILI incidence data. Conclusions: Our work emphasises the common and complementary value of time use and social contact data for analysing mixing behavior and analysing infectious disease transmission. We derived spatial, temporal, age-, gender- and distance-specific mixing patterns, which are informative for future modelling studies. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
4. SOCRATES-CoMix: a platform for timely and open-source contact mixing data during and in between COVID-19 surges and interventions in over 20 European countries
- Author
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Frederik Verelst, Lisa Hermans, Sarah Vercruysse, Amy Gimma, Pietro Coletti, Jantien A. Backer, Kerry L. M. Wong, James Wambua, Kevin van Zandvoort, Lander Willem, Laurens Bogaardt, Christel Faes, Christopher I. Jarvis, Jacco Wallinga, W. John Edmunds, Philippe Beutels, and Niel Hens
- Subjects
Social contact behaviour ,Mixing patterns ,Contact data ,Mathematical modelling ,SARS-CoV-2 ,COVID-19 ,Medicine - Abstract
Abstract Background SARS-CoV-2 dynamics are driven by human behaviour. Social contact data are of utmost importance in the context of transmission models of close-contact infections. Methods Using online representative panels of adults reporting on their own behaviour as well as parents reporting on the behaviour of one of their children, we collect contact mixing (CoMix) behaviour in various phases of the COVID-19 pandemic in over 20 European countries. We provide these timely, repeated observations using an online platform: SOCRATES-CoMix. In addition to providing cleaned datasets to researchers, the platform allows users to extract contact matrices that can be stratified by age, type of day, intensity of the contact and gender. These observations provide insights on the relative impact of recommended or imposed social distance measures on contacts and can inform mathematical models on epidemic spread. Conclusion These data provide essential information for policymakers to balance non-pharmaceutical interventions, economic activity, mental health and wellbeing, during vaccine rollout.
- Published
- 2021
- Full Text
- View/download PDF
5. Investigating the relationship between interventions, contact patterns, and SARS-CoV-2 transmissibility
- Author
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Filippo Trentini, Adriana Manna, Nicoletta Balbo, Valentina Marziano, Giorgio Guzzetta, Samantha O’Dell, Allisandra G. Kummer, Maria Litvinova, Stefano Merler, Marco Ajelli, Piero Poletti, and Alessia Melegaro
- Subjects
COVID-19 ,SARS-CoV-2 ,Social contacts ,Mixing patterns ,Human behavior ,Non-pharmaceutical interventions ,Infectious and parasitic diseases ,RC109-216 - Abstract
Background: After a rapid upsurge of COVID-19 cases in Italy during the fall of 2020, the government introduced a three-tiered restriction system aimed at increasing physical distancing. The Ministry of Health, after periodic epidemiological risk assessments, assigned a tier to each of the 21 Italian regions and autonomous provinces. It is still unclear to what extent these different sets of measures altered the number of daily interactions and the social mixing patterns. Methods and findings: We conducted a survey between July 2020 and March 2021 to monitor changes in social contact patterns among individuals in the metropolitan city of Milan, Italy, which was hardly hit by the second wave of the COVID-19 pandemic. The number of daily contacts during periods characterized by different levels of restrictions was analyzed through negative binomial regression models and age-specific contact matrices were estimated under the different tiers of restrictions. By relying on the empirically estimated mixing patterns, we quantified relative changes in SARS-CoV-2 transmission potential associated with the different tiers.As tighter restrictions were implemented during the fall of 2020, a progressive reduction in the mean number of daily contacts recorded by study participants was observed: from 15.9 % under mild restrictions (yellow tier), to 41.8 % under strong restrictions (red tier). Higher restrictions levels were also found to increase the relative contribution of contacts occurring within the household. The SARS-CoV-2 reproduction number was estimated to decrease by 17.1 % (95 %CI: 1.5–30.1), 25.1 % (95 %CI: 13.0–36.0) and 44.7 % (95 %CI: 33.9–53.0) under the yellow, orange, and red tiers, respectively. Conclusions: Our results give an important quantification of the expected contribution of different restriction levels in shaping social contacts and decreasing the transmission potential of SARS-CoV-2. These estimates can find an operational use in anticipating the effect that the implementation of these tiered restriction can have on SARS-CoV-2 reproduction number under an evolving epidemiological situation.
- Published
- 2022
- Full Text
- View/download PDF
6. A data-driven metapopulation model for the Belgian COVID-19 epidemic: assessing the impact of lockdown and exit strategies
- Author
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Pietro Coletti, Pieter Libin, Oana Petrof, Lander Willem, Steven Abrams, Sereina A. Herzog, Christel Faes, Elise Kuylen, James Wambua, Philippe Beutels, and Niel Hens
- Subjects
COVID-19 ,Behavioral changes ,Metapopulation ,Epidemic modeling ,Spatial transmission ,Mixing patterns ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background In response to the ongoing COVID-19 pandemic, several countries adopted measures of social distancing to a different degree. For many countries, after successfully curbing the initial wave, lockdown measures were gradually lifted. In Belgium, such relief started on May 4th with phase 1, followed by several subsequent phases over the next few weeks. Methods We analysed the expected impact of relaxing stringent lockdown measures taken according to the phased Belgian exit strategy. We developed a stochastic, data-informed, meta-population model that accounts for mixing and mobility of the age-structured population of Belgium. The model is calibrated to daily hospitalization data and is able to reproduce the outbreak at the national level. We consider different scenarios for relieving the lockdown, quantified in terms of relative reductions in pre-pandemic social mixing and mobility. We validate our assumptions by making comparisons with social contact data collected during and after the lockdown. Results Our model is able to successfully describe the initial wave of COVID-19 in Belgium and identifies interactions during leisure/other activities as pivotal in the exit strategy. Indeed, we find a smaller impact of school re-openings as compared to restarting leisure activities and re-openings of work places. We also assess the impact of case isolation of new (suspected) infections, and find that it allows re-establishing relatively more social interactions while still ensuring epidemic control. Scenarios predicting a second wave of hospitalizations were not observed, suggesting that the per-contact probability of infection has changed with respect to the pre-lockdown period. Conclusions Contacts during leisure activities are found to be most influential, followed by professional contacts and school contacts, respectively, for an impending second wave of COVID-19. Regular re-assessment of social contacts in the population is therefore crucial to adjust to evolving behavioral changes that can affect epidemic diffusion.
- Published
- 2021
- Full Text
- View/download PDF
7. Modeling the interplay between demography, social contact patterns, and SARS-CoV-2 transmission in the South West Shewa Zone of Oromia Region, Ethiopia
- Author
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Filippo Trentini, Giorgio Guzzetta, Margherita Galli, Agnese Zardini, Fabio Manenti, Giovanni Putoto, Valentina Marziano, Worku Nigussa Gamshie, Ademe Tsegaye, Alessandro Greblo, Alessia Melegaro, Marco Ajelli, Stefano Merler, and Piero Poletti
- Subjects
COVID-19 ,SARS-CoV-2 ,Mixing patterns ,Contact data ,Rural ,Urban ,Medicine - Abstract
Abstract Background COVID-19 spread may have a dramatic impact in countries with vulnerable economies and limited availability of, and access to, healthcare resources and infrastructures. However, in sub-Saharan Africa, a low prevalence and mortality have been observed so far. Methods We collected data on individuals’ social contacts in the South West Shewa Zone (SWSZ) of Ethiopia across geographical contexts characterized by heterogeneous population density, work and travel opportunities, and access to primary care. We assessed how socio-demographic factors and observed mixing patterns can influence the COVID-19 disease burden, by simulating SARS-CoV-2 transmission in remote settlements, rural villages, and urban neighborhoods, under school closure mandate. Results From national surveillance data, we estimated a net reproduction number of 1.62 (95% CI 1.55–1.70). We found that, at the end of an epidemic mitigated by school closure alone, 10–15% of the population residing in the SWSZ would have been symptomatic and 0.3–0.4% of the population would require mechanical ventilation and/or possibly result in a fatal outcome. Higher infection attack rates are expected in more urbanized areas, but the highest incidence of critical disease is expected in remote subsistence farming settlements. School closure contributed to reduce the reproduction number by 49% and the attack rate of infections by 28–34%. Conclusions Our results suggest that the relatively low burden of COVID-19 in Ethiopia observed so far may depend on social mixing patterns, underlying demography, and the enacted school closures. Our findings highlight that socio-demographic factors can also determine marked heterogeneities across different geographical contexts within the same region, and they contribute to understand why sub-Saharan Africa is experiencing a relatively lower attack rate of severe cases compared to high-income countries.
- Published
- 2021
- Full Text
- View/download PDF
8. Mathematical modeling of COVID-19 in British Columbia: An age-structured model with time-dependent contact rates
- Author
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Sarafa A. Iyaniwura, Rebeca C. Falcão, Notice Ringa, Prince A. Adu, Michelle Spencer, Marsha Taylor, Caroline Colijn, Daniel Coombs, Naveed Z. Janjua, Michael A. Irvine, and Michael Otterstatter
- Subjects
SARS-CoV-2 ,COVID-19 ,Age-structured model ,Mixing patterns ,Epidemics ,Bayesian inference ,Infectious and parasitic diseases ,RC109-216 - Abstract
Following the emergence of COVID-19 at the end of 2019, several mathematical models have been developed to study the transmission dynamics of this disease. Many of these models assume homogeneous mixing in the underlying population. However, contact rates and mixing patterns can vary dramatically among individuals depending on their age and activity level. Variation in contact rates among age groups and over time can significantly impact how well a model captures observed trends. To properly model the age-dependent dynamics of COVID-19 and understand the impacts of interventions, it is essential to consider heterogeneity arising from contact rates and mixing patterns. We developed an age-structured model that incorporates time-varying contact rates and population mixing computed from the ongoing BC Mix COVID-19 survey to study transmission dynamics of COVID-19 in British Columbia (BC), Canada. Using a Bayesian inference framework, we fit four versions of our model to weekly reported cases of COVID-19 in BC, with each version allowing different assumptions of contact rates. We show that in addition to incorporating age-specific contact rates and mixing patterns, time-dependent (weekly) contact rates are needed to adequately capture the observed transmission dynamics of COVID-19. Our approach provides a framework for explicitly including empirical contact rates in a transmission model, which removes the need to otherwise model the impact of many non-pharmaceutical interventions. Further, this approach allows projection of future cases based on clear assumptions of age-specific contact rates, as opposed to less tractable assumptions regarding transmission rates.
- Published
- 2022
- Full Text
- View/download PDF
9. Close contact infection dynamics over time: insights from a second large-scale social contact survey in Flanders, Belgium, in 2010-2011
- Author
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Thang Van Hoang, Pietro Coletti, Yimer Wasihun Kifle, Kim Van Kerckhove, Sarah Vercruysse, Lander Willem, Philippe Beutels, and Niel Hens
- Subjects
Contact rates ,Contact behaviour ,Mixing patterns ,Behavioural changes ,Infectious diseases ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background In 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. Methods Different 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 generalized additive models for location, scale and shape (GAMLSS) model. We compare different matrices using assortativeness measures. The relative change in the basic reproduction number (R 0) 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 sex, 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. Results All estimated contact patterns featured strong homophily in age and sex, especially for small children and adolescents. A 30% (95% BCI [17%; 37%]) and 29% (95% BCI [14%; 40%]) reduction in R 0 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. Conclusions The 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.
- Published
- 2021
- Full Text
- View/download PDF
10. Influence of heterogeneous edge weights on assortative mixing patterns in military personnel networks.
- Author
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McDonald, Chris
- Subjects
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MILITARY personnel , *ARMED Forces , *EDGES (Geometry) ,CANADIAN military - Abstract
A toy model to examine the effect of a heterogeneous edge weight structure on assortative mixing patterns is developed. This model is used as a benchmark to assess assortative mixing patterns in a real military personnel network describing occupation changes among recruits to the Canadian Armed Forces. Mixing patterns on the network suggest a strong tendency for members to transfer between different occupation groups; possible areas on which to focus retention strategies are identified. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
11. SOCRATES-CoMix: a platform for timely and open-source contact mixing data during and in between COVID-19 surges and interventions in over 20 European countries.
- Author
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Verelst, Frederik, Hermans, Lisa, Vercruysse, Sarah, Gimma, Amy, Coletti, Pietro, Backer, Jantien A., Wong, Kerry L. M., Wambua, James, van Zandvoort, Kevin, Willem, Lander, Bogaardt, Laurens, Faes, Christel, Jarvis, Christopher I., Wallinga, Jacco, Edmunds, W. John, Beutels, Philippe, and Hens, Niel
- Subjects
- *
COVID-19 pandemic , *SOCIAL distancing , *SOCIAL contact , *EPIDEMIOLOGICAL models , *SARS-CoV-2 - Abstract
Background: SARS-CoV-2 dynamics are driven by human behaviour. Social contact data are of utmost importance in the context of transmission models of close-contact infections.Methods: Using online representative panels of adults reporting on their own behaviour as well as parents reporting on the behaviour of one of their children, we collect contact mixing (CoMix) behaviour in various phases of the COVID-19 pandemic in over 20 European countries. We provide these timely, repeated observations using an online platform: SOCRATES-CoMix. In addition to providing cleaned datasets to researchers, the platform allows users to extract contact matrices that can be stratified by age, type of day, intensity of the contact and gender. These observations provide insights on the relative impact of recommended or imposed social distance measures on contacts and can inform mathematical models on epidemic spread.Conclusion: These data provide essential information for policymakers to balance non-pharmaceutical interventions, economic activity, mental health and wellbeing, during vaccine rollout. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
12. A data-driven metapopulation model for the Belgian COVID-19 epidemic: assessing the impact of lockdown and exit strategies.
- Author
-
Coletti, Pietro, Libin, Pieter, Petrof, Oana, Willem, Lander, Abrams, Steven, Herzog, Sereina A., Faes, Christel, Kuylen, Elise, Wambua, James, Beutels, Philippe, and Hens, Niel
- Subjects
- *
COVID-19 pandemic , *STAY-at-home orders , *SOCIAL distancing , *SOCIAL contact , *COVID-19 - Abstract
Background: In response to the ongoing COVID-19 pandemic, several countries adopted measures of social distancing to a different degree. For many countries, after successfully curbing the initial wave, lockdown measures were gradually lifted. In Belgium, such relief started on May 4th with phase 1, followed by several subsequent phases over the next few weeks.Methods: We analysed the expected impact of relaxing stringent lockdown measures taken according to the phased Belgian exit strategy. We developed a stochastic, data-informed, meta-population model that accounts for mixing and mobility of the age-structured population of Belgium. The model is calibrated to daily hospitalization data and is able to reproduce the outbreak at the national level. We consider different scenarios for relieving the lockdown, quantified in terms of relative reductions in pre-pandemic social mixing and mobility. We validate our assumptions by making comparisons with social contact data collected during and after the lockdown.Results: Our model is able to successfully describe the initial wave of COVID-19 in Belgium and identifies interactions during leisure/other activities as pivotal in the exit strategy. Indeed, we find a smaller impact of school re-openings as compared to restarting leisure activities and re-openings of work places. We also assess the impact of case isolation of new (suspected) infections, and find that it allows re-establishing relatively more social interactions while still ensuring epidemic control. Scenarios predicting a second wave of hospitalizations were not observed, suggesting that the per-contact probability of infection has changed with respect to the pre-lockdown period.Conclusions: Contacts during leisure activities are found to be most influential, followed by professional contacts and school contacts, respectively, for an impending second wave of COVID-19. Regular re-assessment of social contacts in the population is therefore crucial to adjust to evolving behavioral changes that can affect epidemic diffusion. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
13. Modeling the interplay between demography, social contact patterns, and SARS-CoV-2 transmission in the South West Shewa Zone of Oromia Region, Ethiopia.
- Author
-
Trentini, Filippo, Guzzetta, Giorgio, Galli, Margherita, Zardini, Agnese, Manenti, Fabio, Putoto, Giovanni, Marziano, Valentina, Gamshie, Worku Nigussa, Tsegaye, Ademe, Greblo, Alessandro, Melegaro, Alessia, Ajelli, Marco, Merler, Stefano, and Poletti, Piero
- Subjects
- *
SARS-CoV-2 , *SOCIAL contact , *SOCIAL interaction , *COVID-19 , *DEMOGRAPHY - Abstract
Background: COVID-19 spread may have a dramatic impact in countries with vulnerable economies and limited availability of, and access to, healthcare resources and infrastructures. However, in sub-Saharan Africa, a low prevalence and mortality have been observed so far.Methods: We collected data on individuals' social contacts in the South West Shewa Zone (SWSZ) of Ethiopia across geographical contexts characterized by heterogeneous population density, work and travel opportunities, and access to primary care. We assessed how socio-demographic factors and observed mixing patterns can influence the COVID-19 disease burden, by simulating SARS-CoV-2 transmission in remote settlements, rural villages, and urban neighborhoods, under school closure mandate.Results: From national surveillance data, we estimated a net reproduction number of 1.62 (95% CI 1.55-1.70). We found that, at the end of an epidemic mitigated by school closure alone, 10-15% of the population residing in the SWSZ would have been symptomatic and 0.3-0.4% of the population would require mechanical ventilation and/or possibly result in a fatal outcome. Higher infection attack rates are expected in more urbanized areas, but the highest incidence of critical disease is expected in remote subsistence farming settlements. School closure contributed to reduce the reproduction number by 49% and the attack rate of infections by 28-34%.Conclusions: Our results suggest that the relatively low burden of COVID-19 in Ethiopia observed so far may depend on social mixing patterns, underlying demography, and the enacted school closures. Our findings highlight that socio-demographic factors can also determine marked heterogeneities across different geographical contexts within the same region, and they contribute to understand why sub-Saharan Africa is experiencing a relatively lower attack rate of severe cases compared to high-income countries. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
14. Ecosystem-scale insights into the dynamics of dissolved organic matter in an Asia's largest brackish water lagoon: Sources, fluxes, and biogeochemical significance.
- Author
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Kanuri, Vishnu Vardhan, Muduli, Pradipta Ranjan, Robin, R.S., Basuri, Charan Kumar, Avvari, Lovaraju, Patra, Sivaji, Gupta, G.V.M., Gollapalli, Nageswara Rao, and Subramanian, B.R.
- Subjects
DISSOLVED organic matter ,BRACKISH waters ,LAGOONS ,ENVIRONMENTAL health ,CARBON cycle - Abstract
A twenty-four month long observational study conducted in an Asia's largest brackish water ecosystem, Chilika Lagoon, India, aimed to unravel dissolved organic matter (DOM) dynamics in this tropical brackish water ecosystem. The study assessed the interplay between allochthonous and autochthonous DOM sources during lean and active flow periods based on regional rainfall. Dissolved organic carbon (DOC), nitrogen (DON), and phosphorus (DOP) fluxes were analyzed, considering catchment runoff, phytoplankton production, benthic-pelagic interactions, and sea-lagoon exchanges as contributors. Contrary to conventional thinking, the study found autochthonous processes to be more significant than conservative mixing in shaping DOM dynamics. It introduced a novel conceptual model illustrating the multifaceted origins of DOM, encompassing catchment runoff, phytoplankton, benthic-pelagic interactions, bacterial activity, and sea-lagoon exchanges. These findings underscore the importance of holistic management strategies for Chilika Lagoon to preserve its ecological health, given its vital role in global carbon cycling, fisheries, and aquaculture. [Display omitted] • Results revealed a significant variations in DOM stoichiometry over time. • Sizeable seasonal shifts in benthic DOC fluxes for weedy and non-weedy environment. • Prevalence of autochthonous processes favoured DON and DOP mineralization over DOC. • DOC affected by catchment, phytoplankton, benthic-pelagic, bacteria, and sea exchange. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
15. Mathematical modelling, analysis and simulation of the spread of gangs in interacting youth and adult populations
- Author
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M. Rivera-Castro, P. Padmanabhan, C. Caiseda, P. Seshaiyer, and C. Boria-Guanill
- Subjects
Mixing patterns ,criminal gang ,reproduction number ,stability analysis ,SIR ,modelling and simulation ,Biology (General) ,QH301-705.5 ,Mathematics ,QA1-939 - Abstract
Youth that live in public housing communities with high social and financial needs are at risk of getting involved in illegal drug trafficking gangs that are controlled by adults. This social disease spreads like an epidemic in these densely populated sectors and metropolitan area. In this work, a model based on SIR disease dynamics is used to study the spread of gangs in vulnerable youth and adult sub-populations. Three types of mixing patterns govern interaction between the groups: proportionate, preferred and like-with-like. This new model is analysed presenting formulations for the reproduction number, sensitivity analysis, and stability analysis for the like-with-like mixing. Insights gained from simulation results on the sensitivity of the model to parameters show the relevance of the activity parameter over the reproduction number when heterogeneous mixing is present.
- Published
- 2019
- Full Text
- View/download PDF
16. Close contact infection dynamics over time: insights from a second large-scale social contact survey in Flanders, Belgium, in 2010-2011.
- Author
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Hoang, Thang Van, Coletti, Pietro, Kifle, Yimer Wasihun, Kerckhove, Kim Van, Vercruysse, Sarah, Willem, Lander, Beutels, Philippe, and Hens, Niel
- Subjects
- *
SOCIAL contact , *SOCIAL interaction , *BASIC reproduction number , *OLDER people - Abstract
Background: In 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. Methods: Different 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 generalized additive models for location, scale and shape (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 sex, 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. Results: All estimated contact patterns featured strong homophily in age and sex, 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. Conclusions: The 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. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
17. Conformity: A Path-Aware Homophily Measure for Node-Attributed Networks.
- Author
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Rossetti, Giulio, Citraro, Salvatore, and Milli, Letizia
- Subjects
CONFORMITY ,SOCIAL network analysis - Abstract
Unveiling the homophilic/heterophilic behaviors that characterize the wiring patterns of complex networks is an important task in social network analysis, often approached studying the assortative mixing of node attributes. Recent works have underlined that a global measure to quantify node homophily necessarily provides a partial, often deceiving, picture of the reality. Moving from such literature, in this work, we propose a novel measure, namely Conformity, designed to overcome such limitation by providing a node-centric quantification of assortative mixing patterns. Different from the measures proposed so far, Conformity is designed to be path-aware, thus allowing for a more detailed evaluation of the impact that nodes at different degrees of separations have on the homophilic embeddedness of a target. Experimental analysis on synthetic and real data allowed us to observe that Conformity can unveil valuable insights from node-attributed graphs. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
18. Collaboration in sensor network research: an in-depth longitudinal analysis of assortative mixing patterns
- Author
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Pepe, Alberto and Rodriguez, Marko A.
- Subjects
Computer Science ,Interdisciplinary Studies ,Library Science ,Information Storage and Retrieval ,Scientific collaboration networks ,Sensor network and wireless research ,Network evolution ,Mixing patterns ,Discrete assortativity ,Homophily - Abstract
Many investigations of scientific collaboration are based on statistical analyses of large networks constructed from bibliographic repositories. These investigations often rely on a wealth of bibliographic data, but very little or no other information about the individuals in the network, and thus, fail to illustrate the broader social and academic landscape in which collaboration takes place. In this article, we perform an in-depth longitudinal analysis of a relatively small network of scientific collaboration (N = 291) constructed from the bibliographic record of a research centerin the development and application of wireless and sensor network technologies. We perform a preliminary analysis of selected structural properties of the network, computing its range, configuration and topology. We then support our preliminary statistical analysis with an in-depth temporal investigation of the assortative mixing of selected node characteristics, unveiling the researchers’ propensity to collaborate preferentially with others with a similar academic profile. Our qualitative analysis of mixing patterns offers clues as to the nature of the scientific community being modeled in relation to its organizational, disciplinary, institutional, and international arrangements of collaboration.
- Published
- 2010
19. Experimental studies in antisolvent crystallization: Effect of antisolvent ratio and mixing patterns.
- Author
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Waval, Aniket S., Patel, Pooja, Nemade, Parag R., and Mathpati, Channamallikarjun S.
- Subjects
SALTING out (Chemistry) ,DRUGS ,BIOAVAILABILITY ,SUPERSATURATION ,ULTRASONIC imaging - Abstract
The crystals size and distribution play an important role in drug properties which has a major impact on the performance e.g., stability, solubility and bioavailability. The crystal size distribution (CSD) depends on the hydrodynamics and local degree of supersaturation in the crystallizer. In this study, we have investigated the effects of various operating conditions (antisolvent ratio, power, agitator design) using different mixing techniques such as impellers and ultrasound on CSD and average crystal size (ACS). It is found that mixing plays a dominant role in CSD and ACS. The hydrofoil (axial flow impeller) provides a wide range of ACS (406 to 240 µm) at lower power as compared to Rushton turbine (radial flow impeller) (395 to 375 µm). The mixed flow impeller produces the intermediate crystal size (365 to 345 µm). The increase in the antisolvent ratio results in a decrease in ACS. The same results observed for the power input. [ABSTRACT FROM AUTHOR]
- Published
- 2020
20. The interplay between individual social behavior and clinical symptoms in small clustered groups
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Piero Poletti, Roberto Visintainer, Bruno Lepri, and Stefano Merler
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Mixing patterns ,Time-varying networks ,Risk factor ,Bluetooth proximity ,Influenza-like illness ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background Mixing patterns of human populations play a crucial role in shaping the spreading paths of infectious diseases. The diffusion of mobile and wearable devices able to record close proximity interactions represents a great opportunity for gathering detailed data on social interactions and mixing patterns in human populations. The aim of this study is to investigate how social interactions are affected by the onset of symptomatic conditions and to what extent the heterogeneity in human behavior can reflect a different risk of infection. Methods We study the relation between individuals’ social behavior and the onset of different symptoms, by making use of data collected in 2009 among students sharing a dormitory in a North America university campus. The dataset combines Bluetooth proximity records between study participants with self-reported daily records on their health state. Specifically, we investigate whether individuals’ social activity significantly changes during different symptomatic conditions, including those defining Influenza-like illness, and highlight to what extent possible heterogeneities in social behaviors among individuals with similar age and daily routines may be responsible for a different risk of infection for influenza. Results Our results suggest that symptoms associated with Influenza-like illness can be responsible of a reduction of about 40% in the average duration of contacts and of 30% in the daily time spent in social interactions, possibly driven by the onset of fever. However, differences in the number of daily contacts were found to be not statistically significant. In addition, we found that individuals who experienced clinical influenza during the study period were characterized by a significantly higher social activity. In particular, both the number of person-to-person contacts and the time spent in social interactions emerged as significant risk factors for influenza infection. Conclusions Our findings highlight that Influenza-like illness can remarkably reduce the social activity of individuals and strengthen the idea that the heterogeneity in social habits among individuals can significantly contribute in shaping differences among the individuals’ risk of infection.
- Published
- 2017
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21. Reactive school closure weakens the network of social interactions and reduces the spread of influenza.
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Litvinova, Maria, Quan-Hui Liu, Kulikov, Evgeny S., and Ajelli, Marco
- Subjects
- *
SOCIAL networks , *SOCIAL interaction , *INFLUENZA , *SEASONAL influenza , *SCHOOL absenteeism , *PANDEMICS - Abstract
School-closure policies are considered one of the most promising nonpharmaceutical interventions for mitigating seasonal and pandemic influenza. However, their effectiveness is still debated, primarily due to the lack of empirical evidence about the behavior of the population during the implementation of the policy. Over the course of the 2015 to 2016 influenza season in Russia, we performed a diary-based contact survey to estimate the patterns of social interactions before and during the implementation of reactive school-closure strategies. We develop an innovative hybrid survey-modeling framework to estimate the time-varying network of human social interactions. By integrating this network with an infection transmission model, we reduce the uncertainty surrounding the impact of school-closure policies in mitigating the spread of influenza. When the school-closure policy is in place, we measure a significant reduction in the number of contacts made by students (14.2 vs. 6.5 contacts per day) and workers (11.2 vs. 8.7 contacts per day). This reduction is not offset by the measured increase in the number of contacts between students and nonhousehold relatives. Model simulations suggest that gradual reactive school closure policies based on monitoring student absenteeism rates are capable of mitigating influenza spread. We estimate that without the implemented reactive strategies the attack rate of the 2015 to 2016 influenza season would have been 33% larger. Our study sheds light on the social mixing patterns of the population during the implementation of reactive school closures and provides key instruments for future cost-effectiveness analyses of school-closure policies. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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22. Structural properties of statistically validated empirical information networks.
- Author
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Han, Rui-Qi, Li, Ming-Xia, Chen, Wei, Zhou, Wei-Xing, and Stanley, H. Eugene
- Subjects
- *
INFORMATION networks , *DEFINITIONS , *ECONOPHYSICS - Abstract
We construct the empirical information network (EIN) of traders using the order flow data of the constituent stocks of SZSE 100 Index in 2013. A statistical validation method is applied to the edges of the network to filter out noises and uncover the intrinsic interaction behaviors of traders. We investigate the correlation between topological structures and statistical properties for their largest connected components. We find that the statistical validated network shows an assortative mixing pattern while the original network exhibits a disassortative mixing pattern. We consider two definitions of edge weight for comparison but there is no significant difference in a same network. We also analyze the mutual relationships among node degree, edge weight and node strength. • We construct the empirical information network (EIN) using SZSE stock data. • The statistical validated EINs are obtained. • The raw EIN exhibits a disassortative mixing pattern. • The statistically validated EIN is assortative. • The properties of the giant components of EINs are investigated. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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23. Mathematical modelling, analysis and simulation of the spread of gangs in interacting youth and adult populations.
- Author
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Rivera-Castro, M., Padmanabhan, P., Caiseda, C., Seshaiyer, P., and Boria-Guanill, C.
- Subjects
MATHEMATICAL models ,GANGS - Abstract
Youth that live in public housing communities with high social and financial needs are at risk of getting involved in illegal drug trafficking gangs that are controlled by adults. This social disease spreads like an epidemic in these densely populated sectors and metropolitan area. In this work, a model based on SIR disease dynamics is used to study the spread of gangs in vulnerable youth and adult sub-populations. Three types of mixing patterns govern interaction between the groups: proportionate, preferred and like-with-like. This new model is analysed presenting formulations for the reproduction number, sensitivity analysis, and stability analysis for the like-with-like mixing. Insights gained from simulation results on the sensitivity of the model to parameters show the relevance of the activity parameter over the reproduction number when heterogeneous mixing is present. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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24. Effect of Inclination Angle of Baffled Reactor at Up-Flow on Residence Time Distribution.
- Author
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Bouakaz, Nadji, Bendjama, Zoubida, Hamitouche, Adh’ya-eddine, Amrane, Abdeltif, and Trari, Mohamed
- Subjects
- *
TUBULAR reactors , *BIOTECHNOLOGY , *HYDRODYNAMICS - Abstract
The effect of wave baffles inclination angle on the behavior of a packed bed operating under liquid up-flow was experimentally investigated. The system has been widely used in biotechnology due to the large surface area available for the microorganisms attachment. The results of different flow rates showed that the reactor “e” at θ=180∘
behaves as a plug flow distorted by a constant axial dispersion. At low flow rates, the mean residence time (MRT) and variance residence time (VRT) are high. However, both parameters increase with increasing the height of the sand bed for all reactors “a”, “b”, “c”, “d” and “e” (i.e. θ=0∘,15∘,30∘,45∘ and 180∘ ), respectively, and the flow patterns lie between plug flow and perfectly mixed. Other results of residence time distribution (RTD) obtained from all reactors showed that these reactors do not have segregations or dead volumes and the reactor “c” at θ=30∘ presents a uniform dispersion, high N-tanks number and a low MRT compared with the reference reactor at flat baffles. [ABSTRACT FROM AUTHOR] - Published
- 2018
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25. Scale-up and flow behavior of cohesive granular material in a four-bladed mixer: effect of system and particle size
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Veerakiet Boonkanokwong, Johannes Khinast, and Benjamin J. Glasser
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Physics::Fluid Dynamics ,Impeller ,Materials science ,Mixing patterns ,Mechanics of Materials ,General Chemical Engineering ,Flow (psychology) ,Mixing (process engineering) ,Particle ,Particle size ,Mechanics ,Granular material ,Discrete element method - Abstract
Flow of cohesive granular materials with different moisture contents was examined in a four-bladed mixer via the discrete element method (DEM). Firstly, the mixer diameter (D) was increased while keeping the particle diameter (d) constant. It was observed that when the mixer diameter to the particle diameter ratio (D/d) was larger than a certain critical size (D/d ≥ 75), granular flow behaviors and mixing kinetics followed simple scaling relations. For D/d ≥ 75, flow patterns and mixing kinetics were found to be independent of system size, and velocities of particles scaled linearly with the tip speed of the impeller blades and particle diffusivities scaled with the tip speed of the blades and mixer diameter. These results suggest that past a certain system size the flow and mixing of cohesive particles in large-scale units can be predicted from smaller systems. Secondly, system size was kept constant and particle diameter was changed and it was observed that by keeping the Bond number constant (by changing the level of cohesion) the flow behavior and mixing patterns did not change, showing that larger particles can be used to simulate flow of smaller cohesive particles in a bladed mixer by matching the Bond numbers.
- Published
- 2021
26. Influence of heterogeneous edge weights on assortative mixing patterns in military personnel networks
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Christopher McDonald
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Military personnel ,Mixing patterns ,Artificial Intelligence ,Computer science ,Econometrics ,Computer Vision and Pattern Recognition ,Enhanced Data Rates for GSM Evolution ,Assortative mixing - Abstract
A toy model to examine the effect of a heterogeneous edge weight structure on assortative mixing patterns is developed. This model is used as a benchmark to assess assortative mixing patterns in a real military personnel network describing occupation changes among recruits to the Canadian Armed Forces. Mixing patterns on the network suggest a strong tendency for members to transfer between different occupation groups; possible areas on which to focus retention strategies are identified.
- Published
- 2021
27. Investigation of solid phase mixing in the multistage circulating fluidized bed
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Gongpeng Wu, Mingjian Zhang, and Yan He
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Materials science ,General Chemical Engineering ,Flow (psychology) ,Mixing (process engineering) ,Flux ,02 engineering and technology ,Mechanics ,021001 nanoscience & nanotechnology ,020401 chemical engineering ,Mixing patterns ,Particle ,Fluidized bed combustion ,0204 chemical engineering ,Diffusion (business) ,0210 nano-technology ,Dispersion (chemistry) - Abstract
Solid mixing process plays a crucial role in evaluating the reaction performance of multiphase reactor. However, there still lacks the systematic research on solid mixing for the multistage circulating fluidized bed with enlarged sections. Solid mixing mechanism in a multistage riser is investigated numerically in this study. Some individual characteristics of solid mixing are found. It is shown by analyzing residence time distributions that solid mean residence time and the degree of solid dispersion increase with the increasing solid flux or the decreasing superficial gas velocity. Nevertheless, particle diffusion coefficient increases as solid flux decreases or superficial gas velocity increases. Moreover, the diffusion coefficient in enlarged sections decreases with the increasing height, which is contrary to the variations in traditional risers. Compared with the traditional riser, particle diffusion is weak, but overall solid mixing is enhanced in the multistage riser. Furthermore, two mixing patterns that gas-solid flow develops towards the plug-type flow in the center region of riser and the mixed-type flow in the enlarged section are identified. In addition, the dominant recirculation time of solids in the enlarged section is predicted as 1.5 s under examined cases.
- Published
- 2021
28. Mixing Patterns in Social Trust Networks: A Social Identity Theory Perspective
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Cuiqing Jiang, Yudong Zhang, Xianwen Fang, Shui-Hua Wang, Shixi Liu, and Xiaojing Hu
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Distrust ,Computer science ,Assortativity ,media_common.quotation_subject ,Network theory ,Data science ,Human-Computer Interaction ,Social group ,Mixing patterns ,Modeling and Simulation ,Centrality ,Social identity theory ,Assortative mixing ,Social Sciences (miscellaneous) ,media_common - Abstract
Mixing patterns (MPs) in social trust networks (STNs) are increasingly attracting attention because they can assist analysts in designing information dissemination tactics and planning electronic word-of-mouth (eWOM) campaigns. However, the existing studies on MPs do not explain the assortative or disassortative tendencies of STNs due to their omission of the support of the sociological theory, as well as that of network theory. To address this issue, this study investigates the MPs in STNs from the standpoint of social identity theory (SIT). The user trust networks (UTNs) are modeled by a directed multigraph (DMG). Then, the structural properties of homogeneous trust networks and heterogeneous trust networks are explored via measures that include degree centrality, the correlation coefficient (CC), the cumulative distribution of the ratio of trust degree to distrust degree (CDRTD), and the assortativity coefficient. The MPs of homogeneous trust networks and heterogeneous trust networks are explained from the perspective of SIT. An experiential evaluation is conducted in the constructed homogeneous trust networks and heterogeneous trust networks using a real-world data set crawled from Epinions. The research findings indicate that the MPs in homogeneous trust networks tend toward assortative mixing (AM), and those in heterogeneous trust networks tend toward disassortative mixing (DM). The experimental results show that the performance of the proposed approach is superior to that of the state-of-the-art approach to influential user identification.
- Published
- 2021
29. Analyzing Trust-Based Mixing Patterns in Signed Networks
- Author
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Rathore, Amit Singh, Mutalikdesai, Mandar R., Patil, Sanket, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Urs, Shalini R., editor, Na, Jin-Cheon, editor, and Buchanan, George, editor
- Published
- 2013
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30. Wearable Sensor Networks for Measuring Face-to-Face Contact Patterns in Healthcare Settings
- Author
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Barrat, Alain, Cattuto, Ciro, Colizza, Vittoria, Isella, Lorenzo, Rizzo, Caterina, Tozzi, Alberto E., Van den Broeck, Wouter, Akan, Ozgur, Series editor, Bellavista, Paolo, Series editor, Cao, Jiannong, Series editor, Dressler, Falko, Series editor, Ferrari, Domenico, Series editor, Gerla, Mario, Series editor, Kobayashi, Hisashi, Series editor, Palazzo, Sergio, Series editor, Sahni, Sartaj, Series editor, Shen, Xuemin (Sherman), Series editor, Stan, Mircea, Series editor, Xiaohua, Jia, Series editor, Zomaya, Albert, Series editor, Coulson, Geoffrey, Series editor, Szomszor, Martin, editor, and Kostkova, Patty, editor
- Published
- 2012
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31. SOCRATES-CoMix: a platform for timely and open-source contact mixing data during and in between COVID-19 surges and interventions in over 20 European countries
- Author
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Philippe Beutels, Christel Faes, Pietro Coletti, Lisa Hermans, Amy Gimma, Kerry L. M. Wong, Lander Willem, James Wambua, Sarah Vercruysse, Niel Hens, Frederik Verelst, Christopher I Jarvis, Kevin van Zandvoort, W. John Edmunds, Jacco Wallinga, Laurens Bogaardt, Jantien A. Backer, Willem, Lander/0000-0002-9210-1196, Coletti, Pietro/0000-0001-9935-1692, Verelst, Frederik/0000-0001-8399-743X, Jarvis, Christopher/0000-0002-0812-2446, Verelst, Frederik, HERMANS, Lisa, VERCRUYSSE, Sarah, Gimma, Amy, COLETTI, Pietro, Backer, Jantien A., Wong, Kerry L. M., WAMBUA, James, van Zandvoort, Kevin, WILLEM, Lander, Bogaardt, Laurens, Faes, Christel, Jarvis, Christopher, I, Wallinga, Jacco, Edmunds, W. John, Beutels, Philippe, and HENS, Niel
- Subjects
Adult ,Coronavirus disease 2019 (COVID-19) ,Internet privacy ,Psychological intervention ,Context (language use) ,modelling ,SARS-CoV-2 ,COVID-19 ,Europe ,Database ,03 medical and health sciences ,0302 clinical medicine ,Medicine, General & Internal ,General & Internal Medicine ,Pandemic ,Medicine ,Humans ,Contact data ,030212 general & internal medicine ,Social contact behaviour ,Mixing patterns ,Mathematical ,Child ,Pandemics ,Mixing (physics) ,030304 developmental biology ,0303 health sciences ,Science & Technology ,Mathematical modelling ,business.industry ,Social distance ,General Medicine ,Models, Theoretical ,Mental health ,SOCRATES ,Human medicine ,SPREAD ,business ,Life Sciences & Biomedicine - Abstract
Background SARS-CoV-2 dynamics are driven by human behaviour. Social contact data are of utmost importance in the context of transmission models of close-contact infections. Methods Using online representative panels of adults reporting on their own behaviour as well as parents reporting on the behaviour of one of their children, we collect contact mixing (CoMix) behaviour in various phases of the COVID-19 pandemic in over 20 European countries. We provide these timely, repeated observations using an online platform: SOCRATES-CoMix. In addition to providing cleaned datasets to researchers, the platform allows users to extract contact matrices that can be stratified by age, type of day, intensity of the contact and gender. These observations provide insights on the relative impact of recommended or imposed social distance measures on contacts and can inform mathematical models on epidemic spread. Conclusion These data provide essential information for policymakers to balance non-pharmaceutical interventions, economic activity, mental health and wellbeing, during vaccine rollout.
- Published
- 2021
32. Fingerprint for Network Topologies
- Author
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Guo, Yuchun, Chen, Changjia, Zhou, Shi, Akan, Ozgur, Series editor, Bellavista, Paolo, Series editor, Cao, Jiannong, Series editor, Dressler, Falko, Series editor, Ferrari, Domenico, Series editor, Gerla, Mario, Series editor, Kobayashi, Hisashi, Series editor, Palazzo, Sergio, Series editor, Sahni, Sartaj, Series editor, Shen, Xuemin (Sherman), Series editor, Stan, Mircea, Series editor, Xiaohua, Jia, Series editor, Zomaya, Albert, Series editor, Coulson, Geoffrey, Series editor, and Zhou, Jie, editor
- Published
- 2009
- Full Text
- View/download PDF
33. A data-driven metapopulation model for the Belgian COVID-19 epidemic: assessing the impact of lockdown and exit strategies
- Author
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Niel Hens, Pieter Libin, Oana Petrof, Steven Abrams, Philippe Beutels, Christel Faes, Lander Willem, Pietro Coletti, Elise Kuylen, Sereina A. Herzog, James Wambua, and Informatics and Applied Informatics
- Subjects
0301 basic medicine ,TRANSMISSION ,030231 tropical medicine ,Physical Distancing ,Population ,Metapopulation ,schools ,Infectious and parasitic diseases ,RC109-216 ,Phase (combat) ,03 medical and health sciences ,0302 clinical medicine ,Belgium ,Mixing patterns ,Pandemic ,Spatial transmission ,Humans ,030212 general & internal medicine ,education ,Belgium/epidemiology ,Pandemics ,COVID-19/epidemiology ,education.field_of_study ,Science & Technology ,Exit strategy ,Social distance ,COVID-19 ,Models, Theoretical ,3. Good health ,Hospitalization ,workplace ,030104 developmental biology ,Infectious Diseases ,Geography ,Behavioral changes ,Work (electrical) ,Epidemic modeling ,Communicable Disease Control ,Demographic economics ,Human medicine ,Business ,Life Sciences & Biomedicine ,Contact tracing ,Research Article - Abstract
Background In response to the ongoing COVID-19 pandemic, several countries adopted measures of social distancing to a different degree. For many countries, after successfully curbing the initial wave, lockdown measures were gradually lifted. In Belgium, such relief started on May 4th with phase 1, followed by several subsequent phases over the next few weeks. Methods We analysed the expected impact of relaxing stringent lockdown measures taken according to the phased Belgian exit strategy. We developed a stochastic, data-informed, meta-population model that accounts for mixing and mobility of the age-structured population of Belgium. The model is calibrated to daily hospitalization data and is able to reproduce the outbreak at the national level. We consider different scenarios for relieving the lockdown, quantified in terms of relative reductions in pre-pandemic social mixing and mobility. We validate our assumptions by making comparisons with social contact data collected during and after the lockdown. Results Our model is able to successfully describe the initial wave of COVID-19 in Belgium and identifies interactions during leisure/other activities as pivotal in the exit strategy. Indeed, we find a smaller impact of school re-openings as compared to restarting leisure activities and re-openings of work places. We also assess the impact of case isolation of new (suspected) infections, and find that it allows re-establishing relatively more social interactions while still ensuring epidemic control. Scenarios predicting a second wave of hospitalizations were not observed, suggesting that the per-contact probability of infection has changed with respect to the pre-lockdown period. Conclusions Contacts during leisure activities are found to be most influential, followed by professional contacts and school contacts, respectively, for an impending second wave of COVID-19. Regular re-assessment of social contacts in the population is therefore crucial to adjust to evolving behavioral changes that can affect epidemic diffusion. This work received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (PC and NH, grant number 682540 – TransMID project, PL, NH, PB grant number 101003688 – EpiPose project). SA and NH gratefully acknowledge support from the Fonds voor Wetenschappelijk Onderzoek (FWO) (RESTORE project – G0G2920N). LW received funding from the Research Foundation Flanders (1234620N). PL received funding from the Research Foundation Flanders (post-doctoral grant 1242021N). The resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation – Flanders (FWO) and the Flemish Government. We thank several researchers from the SIMID COVID-19 consortium from the University of Antwerp and Hasselt University for numerous constructive discussions and meetings. We thank Giulia Pullano, Laura Di Domenico and Vittoria Colizza for useful discussions. The authors are also very grateful for access to the data from the Belgian Scientific Institute for Public Health, Sciensano.
- Published
- 2021
34. Numerical Investigation of Producer Gas Combustion Under Different Mixing Patterns of Air–Fuel Injections in a Cyclone Combustor
- Author
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Lemthong Chanphavong and Keophousone Phonhalath
- Subjects
Multidisciplinary ,Mixing patterns ,Combustion process ,Combustor ,Environmental science ,Cyclone ,Thermal power station ,Producer gas ,Mechanics ,Dissipation ,Combustion - Abstract
This paper presents numerical modeling to determine characteristics of producer gas combustion in a cyclone combustor under different air–fuel mixing patterns. The burner was configured by varying in premixed, non-premixed, and co-flow modes. The combustion process was operated at a thermal power input of about 50 kW with respect to ambient conditions of air–fuel injections. The numerical modeling was carried out using the eddy dissipation concept combustion model integrated with a 17 species skeletal (SK17) reaction mechanism. The numerical result was validated with the existing experimental data before implementing the studied cases. Swirling flow field and combustion characteristics were compared for all three cases. It could be concluded that the premixed combustion mode was a better option in comparison with two other cases, considering that it gives higher swirling flow field characteristics, leading to a good result in combustion efficiency and lower both CO and NO emissions.
- Published
- 2021
35. Conformity: A Path-Aware Homophily Measure for Node-Attributed Networks
- Author
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Letizia Milli, Salvatore Citraro, and Giulio Rossetti
- Subjects
Social and Information Networks (cs.SI) ,FOS: Computer and information sciences ,Theoretical computer science ,Computer Networks and Communications ,Computer science ,Node (networking) ,media_common.quotation_subject ,Mixing patterns ,Attributed networks ,Computer Science - Social and Information Networks ,02 engineering and technology ,Complex network ,Homophily ,Conformity ,Measure (mathematics) ,Artificial Intelligence ,Path (graph theory) ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Assortative mixing ,Social network analysis ,media_common - Abstract
Unveil the homophilic/heterophilic behaviors that characterize the wiring patterns of complex networks is an important task in social network analysis, often approached studying the assortative mixing of node attributes. Recent works underlined that a global measure to quantify node homophily necessarily provides a partial, often deceiving, picture of the reality. Moving from such literature, in this work, we propose a novel measure, namely Conformity, designed to overcome such limitation by providing a node-centric quantification of assortative mixing patterns. Differently from the measures proposed so far, Conformity is designed to be path-aware, thus allowing for a more detailed evaluation of the impact that nodes at different degrees of separations have on the homophilic embeddedness of a target. Experimental analysis on synthetic and real data allowed us to observe that Conformity can unveil valuable insights from node-attributed graphs., Comment: Submitted to IEEE Intelligent Systems
- Published
- 2021
36. Age-specific social mixing of school-aged children in a US setting using proximity detecting sensors and contact surveys
- Author
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Charles J. Vukotich, Jonathan M. Read, Gabby M. H. Yearwood, Hongjiang Gao, Jeanette J. Rainey, Eva Noble, Hasan Guclu, Mary Lou Schweizer, Jennifer Cousins, Patti Calderone, Kan Li, Shanta M. Zimmer, David Galloway, Amra Uzicanin, Derek A. T. Cummings, Carrie Lingle, and Kyra H. Grantz
- Subjects
Male ,0301 basic medicine ,Adolescent ,Epidemiology ,Science ,Wearable computer ,Article ,03 medical and health sciences ,Survey methodology ,0302 clinical medicine ,Mixing patterns ,Surveys and Questionnaires ,Proximity sensor ,Statistics ,Humans ,030212 general & internal medicine ,Child ,Mixing (physics) ,Ecological epidemiology ,Multidisciplinary ,Ecology ,Age specific ,Social relation ,030104 developmental biology ,Geography ,Virus Diseases ,Viral infection ,Child, Preschool ,Respiratory virus ,Medicine ,Female ,Contact Tracing - Abstract
Comparisons of the utility and accuracy of methods for measuring social interactions relevant to disease transmission are rare. To increase the evidence base supporting specific methods to measure social interaction, we compared data from self-reported contact surveys and wearable proximity sensors from a cohort of schoolchildren in the Pittsburgh metropolitan area. Although the number and type of contacts recorded by each participant differed between the two methods, we found good correspondence between the two methods in aggregate measures of age-specific interactions. Fewer, but longer, contacts were reported in surveys, relative to the generally short proximal interactions captured by wearable sensors. When adjusted for expectations of proportionate mixing, though, the two methods produced highly similar, assortative age-mixing matrices. These aggregate mixing matrices, when used in simulation, resulted in similar estimates of risk of infection by age. While proximity sensors and survey methods may not be interchangeable for capturing individual contacts, they can generate highly correlated data on age-specific mixing patterns relevant to the dynamics of respiratory virus transmission.
- Published
- 2021
37. Mathematical modeling, analysis, and simulation of the COVID-19 pandemic with explicit and implicit behavioral changes
- Author
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Kirthi Kumar, Comfort Ohajunwa, and Padmanabhan Seshaiyer
- Subjects
Computer science ,QC1-999 ,Population ,Biophysics ,social behavior ,Next-generation matrix ,Mixing patterns ,Econometrics ,education ,Molecular Biology ,Mathematical Physics ,Graphical user interface ,education.field_of_study ,34axx ,Mathematical model ,business.industry ,Applied Mathematics ,Physics ,92bxx ,Computational Mathematics ,Range (mathematics) ,Transmission (telecommunications) ,covid-19 ,92-08 ,business ,Basic reproduction number ,compartmental model ,TP248.13-248.65 ,Biotechnology - Abstract
As COVID-19 cases continue to rise globally, many researchers have developed mathematical models to help capture the dynamics of the spread of COVID-19. Specifically, the compartmental SEIR model and its variations have been widely employed. These models differ in the type of compartments included, nature of the transmission rates, seasonality, and several other factors. Yet, while the spread of COVID-19 is largely attributed to a wide range of social behaviors in the population, several of these SEIR models do not account for such behaviors. In this project, we consider novel SEIR-based models that incorporate various behaviors. We created a baseline model and explored incorporating both explicit and implicit behavioral changes. Furthermore, using the Next Generation Matrix method, we derive a basic reproduction number, which indicates the estimated number of secondary cases by a single infected individual. Numerical simulations for the various models we made were performed and user-friendly graphical user interfaces were created. In the future, we plan to expand our project to account for the use of face masks, age-based behaviors and transmission rates, and mixing patterns.
- Published
- 2020
38. The Family of Assortativity Coefficients in Signed Social Networks
- Author
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Ai-Wen Li, Xiao-Ke Xu, and Jing Xiao
- Subjects
Physics::Physics and Society ,Theoretical computer science ,Degree (graph theory) ,Computer science ,Assortativity ,Node (networking) ,020206 networking & telecommunications ,020207 software engineering ,Computer Science::Social and Information Networks ,02 engineering and technology ,Function (mathematics) ,Measure (mathematics) ,Human-Computer Interaction ,Correlation ,Mixing patterns ,Null (SQL) ,Modeling and Simulation ,0202 electrical engineering, electronic engineering, information engineering ,Social Sciences (miscellaneous) - Abstract
Signed networks are a special type of networks with both positive and negative edges, and the signs of links play a significant role in functional analysis and structural evolution. Because of the particularity of signed networks, the existing methods to measure their degree assortativity only rely on dividing the original network by link signs ignoring the signs of node degrees, which cannot measure the complicated degree mixing patterns. In this study, considering the complex types of link signs and node degree signs, we propose four new mixing patterns that have not been measured before for signed social networks and define a set of six signed assortativity measures based on traditional assortativity coefficients, to form a complete family of assortativity coefficients. The statistical significance of the family of assortativity coefficients is confirmed by comparing with null models, showing the assortativity significance profile (ASP) of different empirical signed networks. Besides, the relationship and distinction between the family of assortativity coefficients and classical network indexes, such as excess average degree and network embeddedness, are analyzed, revealing the endogenous complexity of signed social networks and the diversity of their assortativities. The proposed method enriches the assortativity diversity of social networks, which is beneficial to measure and analyze complex structure, function, and evolution of real-world social networks.
- Published
- 2020
39. Rare earth elements in the East Sea (Japan Sea): Distributions, behaviors, and applications
- Author
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Hojong Seo and Guebuem Kim
- Subjects
Water mass ,010504 meteorology & atmospheric sciences ,Asian Dust ,Rare earth ,Fold (geology) ,010502 geochemistry & geophysics ,01 natural sciences ,Pacific ocean ,Oceanography ,Mixing patterns ,Geochemistry and Petrology ,Warm water ,Scavenging ,Geology ,0105 earth and related environmental sciences - Abstract
The distributions of rare earth elements (REEs) were measured at 14 stations from 0 to 3365 m (n = 176) in the entire East Sea for the first time. The East Sea has its own deep-convection system, which operates on a time scale that is approximately one tenth that of the global ocean; it is also a downwind region of Asian dust. The vertical distributions of REE concentrations increased with depth, similar to those in the North Atlantic Ocean. However, the concentrations of REEs were 1.3–2.7 fold higher than those in the North Atlantic Ocean, associated with relatively larger atmospheric depositions of dust from the Asian continent. In this environmental condition, the removal of Ce relative to the other REEs was about an order of magnitude more efficient than that in the North Pacific Ocean. As such, in the deep layer below 750 m, large increases of heavy-REEs (HREEs) relative to light-REEs (LREEs), opposite to the re-mineralization trend, were observed suggesting that LREEs were preferentially re-scavenged by sinking particles. In addition, the boundary scavenging of REEs was also observed for all REEs in the bottom layer of the East Sea. On the other hand, the warm surface waters of REEs, Tsushima Warm Water (TWW) showed large fractionations, relative to the other water masses. This REE pattern traced the deep physical mixing proportions of TWW up to 750 m (∼10%). Thus, the unique distribution patterns of REEs in this sea illustrate the geochemical scavenging characteristics of REEs, which are concealed in the major oceans, as well as water mass mixing patterns in the upper ocean.
- Published
- 2020
40. Adaptive data-driven age and patch mixing in contact networks with recurrent mobility
- Author
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Sharmistha Mishra, Kevin R. Brown, Jesse Knight, Mackenzi Hamilton, Huiting Ma, and Amir Ghasemi
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education.field_of_study ,contact patterns ,Infectious disease transmission ,Science ,Clinical Biochemistry ,Population ,COVID-19 ,Contact type ,Geometry ,age groups ,Method Article ,Contact patterns in patch-based models with recurrent mobility ,transmission modelling ,Data-driven ,Medical Laboratory Technology ,Mixing patterns ,Age groups ,heterogeneous mixing ,population mobility ,Age distribution ,education ,Mixing (physics) ,ComputingMethodologies_COMPUTERGRAPHICS ,Mathematics - Abstract
Graphical abstract, Infectious disease transmission models often stratify populations by age and geographic patches. Contact patterns between age groups and patches are key parameters in such models. Arenas et al. (2020) develop an approach to simulate contact patterns associated with recurrent mobility between patches, such as due to work, school, and other regular travel. Using their approach, mixing between patches is greater than mobility data alone would suggest, because individuals from patches A and B can form contacts if they meet in patch C. We build upon their approach to address three potential gaps that remain, outlined in the bullets below. We describe the steps required to implement our approach in detail, and present step-wise results of an example application to generate contact matrices for SARS-CoV-2 transmission modelling in Ontario, Canada. We also provide methods for deriving the mobility matrix based on GPS mobility data (appendix). • Our approach includes a distribution of contacts by age that is responsive to the underlying age distributions of the mixing populations. • Our approach maintains different age mixing patterns by contact type, such that changes to the numbers of different types of contacts are appropriately reflected in changes to overall age mixing patterns. • Our approach distinguishes between two mixing pools associated with each patch, with possible implications for the overall connectivity of the population: the home pool, in which contacts can only be formed with other individuals residing in the same patch, and the travel pool, in which contacts can be formed with some residents of, and any other visitors to the patch.
- Published
- 2022
41. The interplay between individual social behavior and clinical symptoms in small clustered groups.
- Author
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Poletti, Piero, Visintainer, Roberto, Lepri, Bruno, and Merler, Stefano
- Subjects
- *
PREVENTION of communicable diseases , *HUMAN behavior , *SOCIAL interaction , *COMMUNICABLE diseases , *TIME-varying systems , *DISEASE risk factors , *INFLUENZA transmission , *INFLUENZA epidemiology , *FEVER , *HOUSING , *INFLUENZA , *INTERPERSONAL relations , *SELF-evaluation , *SOCIAL skills , *STUDENTS , *UNIVERSITIES & colleges , *PSYCHOLOGY - Abstract
Background: Mixing patterns of human populations play a crucial role in shaping the spreading paths of infectious diseases. The diffusion of mobile and wearable devices able to record close proximity interactions represents a great opportunity for gathering detailed data on social interactions and mixing patterns in human populations. The aim of this study is to investigate how social interactions are affected by the onset of symptomatic conditions and to what extent the heterogeneity in human behavior can reflect a different risk of infection.Methods: We study the relation between individuals' social behavior and the onset of different symptoms, by making use of data collected in 2009 among students sharing a dormitory in a North America university campus. The dataset combines Bluetooth proximity records between study participants with self-reported daily records on their health state. Specifically, we investigate whether individuals' social activity significantly changes during different symptomatic conditions, including those defining Influenza-like illness, and highlight to what extent possible heterogeneities in social behaviors among individuals with similar age and daily routines may be responsible for a different risk of infection for influenza.Results: Our results suggest that symptoms associated with Influenza-like illness can be responsible of a reduction of about 40% in the average duration of contacts and of 30% in the daily time spent in social interactions, possibly driven by the onset of fever. However, differences in the number of daily contacts were found to be not statistically significant. In addition, we found that individuals who experienced clinical influenza during the study period were characterized by a significantly higher social activity. In particular, both the number of person-to-person contacts and the time spent in social interactions emerged as significant risk factors for influenza infection.Conclusions: Our findings highlight that Influenza-like illness can remarkably reduce the social activity of individuals and strengthen the idea that the heterogeneity in social habits among individuals can significantly contribute in shaping differences among the individuals' risk of infection. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF
42. Computational Fluid Dynamics study of the CREC Riser Simulator: Mixing patterns.
- Author
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Ahmed, I., Rostom, S., Lanza, A., and De Lasa, H.
- Subjects
- *
COMPUTATIONAL fluid dynamics , *CHEMICAL reactors , *FLUX flow , *FLUIDIZATION , *GAS-solid interfaces , *EQUIPMENT & supplies - Abstract
The CREC Riser Simulator Reactor is a novel mini-Riser unit. This study considers a laminar-turbulent CFD (Computational Fluid Dynamics) simulation using the COMSOL Multiphysics® module to establish gas-solid mixing patterns. The proposed CFD calculations are verified using both experimental data (< 10–15% difference) and mass balance errors (< 0.1%). Results show the significant detrimental effect of basket vertical baffles implemented in earlier designs of the CREC Riser Simulator Reactor. On the basis of this, it is demonstrated that a double vortex flow leading to high gas mixing is favored in a new reactor configuration “without” basket vertical baffles. For instance, at 4200 rpm, in a basket unit loaded with 0.8 g of catalyst, close to ~ 69 cm/s gas axial velocities were observed. This shows turbulent or fast fluidization conditions with smaller than 0.51 s mixing times. In addition, this new suggested design with enhanced mixing places the CREC Riser Simulator in a new class of laboratory scale fluidized catalytic units. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
43. Mixing patterns and deep chlorophyll a maxima in an eutrophic tropical lake in western Mexico
- Author
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Gabriela Vázquez and Margarita Caballero
- Subjects
0106 biological sciences ,Chlorophyll a ,010604 marine biology & hydrobiology ,Aquatic Science ,010603 evolutionary biology ,01 natural sciences ,chemistry.chemical_compound ,Nutrient ,Water column ,Oceanography ,chemistry ,Mixing patterns ,Chlorophyll ,Environmental science ,Water quality ,Hypolimnion ,Eutrophication - Abstract
In many temperate oligotrophic lakes, algal accumulations can form below the mixing zone. However, Deep Chlorophyll Maxima (DCM) have also been found in some eutrophic, tropical lakes and in this paper we aim to identify if they are recurrent features in these kinds of lakes and to recognize the factors that favor their formation. We analyzed 5 years of thermal stratification, water quality, and chlorophyll a concentrations in a tropical eutrophic lake in Central Mexico. Thermal stratification patterns were characteristic of warm monomictic lakes. Full water column deoxygenation during winter mixing was recorded in 3 of the analyzed years, and an increase of ~ 1 °C in the hypolimnion was detected between 2011 and 2015. DCM were detected in 4 out of the 5 studied years, at the top of the hypolimnion when the water column was stratified (spring–summer). This study is the first report of recurrent DCM formation in the northern limit of the Neotropics. It confirms that high light penetration is a necessary condition for DCM. Stratified nutrients with epilimnetic P depletion are also factors favoring DCM formation.
- Published
- 2020
44. Minnesota Social Contacts and Mixing Patterns Survey with Implications for Modelling of Infectious Disease Transmission and Control
- Author
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Eva A. Enns, Alisha Simon, Audrey Dorélien, Kathleen Thiede Call, Sarah Hagge, and Shalini L Kulasingam
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0303 health sciences ,medicine.medical_specialty ,Infectious disease transmission ,Social distance ,Public health ,Psychological intervention ,03 medical and health sciences ,Survey methodology ,0302 clinical medicine ,Geography ,Mixing patterns ,Infectious disease (medical specialty) ,Environmental health ,medicine ,030212 general & internal medicine ,Survey instrument ,030304 developmental biology - Abstract
Emerging infectious diseases, such as the 2019 novel coronavirus (SARS-CoV-2), pose a substantial challenge to United States (US) public health. In the absence of a vaccine, controlling the spread of SARS-CoV-2 depends on social distancing measures, such as school closures and stay-at-home orders. Infectious disease epidemiologists create models to test the effects of these different interventions and to predict their impact on different populations. One key input to these models is data on social contact and mixing patterns. Unfortunately, there is a paucity of this type of data for the US. The Minnesota Department of Health and University of Minnesota launched the Minnesota Social Contact Study (MN SCS) in order to capture social contact and mixing pattern data for MN as different social distancing measures are enacted. This report describes the MN SCS survey and survey methodology. We highlight key differences between the MN SCS and the most widely cited and used social contact survey based on data from eight European countries in 2006. We conclude by highlighting changes others may consider when adopting the survey for use in other populations. A copy of the survey instrument is included in the appendix.
- Published
- 2020
45. Assortative Analysis of Bulk Trade Complex Network on Maritime Silk Road
- Author
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Naixia Mou, Yujie Fang, Tengfei Yang, and Lingxian Zhang
- Subjects
assortativity ,0209 industrial biotechnology ,General Computer Science ,Node (networking) ,Assortativity ,Scale (chemistry) ,AIS ,General Engineering ,02 engineering and technology ,Complex network ,Port (computer networking) ,Maritime Silk Road ,020901 industrial engineering & automation ,Mixing patterns ,Trade strategy ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,General Materials Science ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,bulk ,lcsh:TK1-9971 ,Assortative mixing ,trade network ,Industrial organization - Abstract
Assortativity, one of the mixing patterns of complex networks, is characterized by measuring whether the nodes are preferentially connected to the nodes with a similar scale. While numerous studies have examined the assortative characteristics of various real-world networks, few studies have attempted to analyze the assortativity of networks in which the subject of trade is bulk. The novelty of this research is that, for the first time, the assortative coefficient method in physics is introduced into the bulk trade network, and the Automatic Identification System (AIS) data is used to explore the assortative mixing characteristics of the network. From the perspective of multi-scale (port and country) and multi-dimensional (node, link, and network) structure, this paper reveals the tendency of trade connection and explores the trade rules of bulk in networks. The results show that: (1) The trade network of bulk on the Maritime Silk Road is assortative. With the increase of spatial scale, the extent of assortativity is also gradually increasing; (2) In the bulk network of ports, trade cooperation shows the rule of distance attenuation; In the national bulk network, it shows the rule of preferential connection; (3) Ports with high out-degree will export bulk to the ports with high out-degree with broad market, while countries with high out-degree export to high in-degree countries with strong demand. The present study is expected to provide valuable references for port planning, national formulation of scientific bulk trade strategy, and promotion of coordinated development of bulk trade network along the Maritime Silk Road.
- Published
- 2020
46. Categorization of atomic mixing patterns in bimetallic nanoparticles by the energy competition
- Author
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Ho-Seok Nam, Kayoung Yun, and Seungchul Kim
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Work (thermodynamics) ,education.field_of_study ,Materials science ,Population ,General Physics and Astronomy ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Surface energy ,0104 chemical sciences ,Mixing patterns ,Chemical physics ,Physical and Theoretical Chemistry ,Bond energy ,0210 nano-technology ,education ,Bimetallic strip ,Phase diagram - Abstract
The superior properties of bimetallic nanoparticles are strongly related to their morphology. A better understanding of the morphological details would be the first step to design bimetallic nanoparticles for target applications. In this study, we discussed three possible categories of the atomic mixing patterns of bimetallic nanoparticles using the concept of competition between bond energy and surface energy. The categorization was confirmed with the thermodynamically stable structures of AgPt, AuPt, CuPt, PdPt, AgPd, AuPd, and CuPd obtained using Monte Carlo simulations. This work also proposed the phase diagrams of AuPt, CuPt, and PdPt nanoparticles, which displayed the details of atomic arrangements depending on the changes in size and atomic composition. The population in low-coordination sites and temperature effects were also intensively studied. The comprehensive understanding of these factors would facilitate the rational design and wide applications of bimetallic nanoparticles.
- Published
- 2020
47. Investigating the relationship between interventions, contact patterns, and SARS-CoV-2 transmissibility
- Author
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Nicoletta Balbo, Giorgio Guzzetta, Marco Ajelli, Stefano Merler, Filippo Trentini, Valentina Marziano, Piero Poletti, Alessia Melegaro, and Adriana Manna
- Subjects
PANDEMICS ,Epidemiology ,Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ,Population ,Negative binomial distribution ,Psychological intervention ,NON-PHARMACEUTICAL INTERVENTIONS ,SARS-COV-2 ,SOCIAL CONTACTS ,Microbiology ,COVID-19, HUMAN BEHAVIOR, MIXING PATTERNS, NON-PHARMACEUTICAL INTERVENTIONS, REPRODUCTION NUMBER, SARS-COV-2, SOCIAL CONTACTS, TIERS, TRANSMISSIBILITY, FAMILY CHARACTERISTICS, HUMANS, PANDEMICS, SURVEYS AND QUESTIONNAIRES, COVID-19, SARS-COV-2 ,REPRODUCTION NUMBER ,Mixing patterns ,Virology ,HUMAN BEHAVIOR ,education ,education.field_of_study ,Public Health, Environmental and Occupational Health ,COVID-19 ,HUMANS ,Metropolitan area ,FAMILY CHARACTERISTICS ,SURVEYS AND QUESTIONNAIRES ,Transmissibility (vibration) ,MIXING PATTERNS ,Infectious Diseases ,Geography ,TIERS ,Parasitology ,TRANSMISSIBILITY ,Risk assessment ,Demography - Abstract
BackgroundAfter a rapid upsurge of COVID-19 cases in Italy during the fall of 2020, the government introduced a three-tiered restriction system aimed at increasing physical distancing. The Ministry of Health, after periodic epidemiological risk assessments, assigned a tier to each of the 21 Italian regions and autonomous provinces (AP). It is still unclear to what extent these different measures altered mixing patterns and how quickly the population adapted their social interactions to continuous changes in restrictions.Methods and findingsWe conducted a survey between July 2020 and March 2021 to monitor changes in social contact patterns among individuals in the metropolitan city of Milan, Italy, which was hardly hit by the second wave of COVID-19 pandemic. The number of contacts during periods characterized by different levels of restrictions was analyzed through negative binomial regression models and age-specific contact matrices were estimated under the different tiers. Relying on the empirically estimated mixing patterns, we quantified relative changes in SARS-CoV-2 transmission potential associated with the different tiers.As tighter restrictions were implemented during the fall of 2020, a progressive reduction in the mean number of contacts recorded by study participants was observed: from 16.4% under mild restrictions (yellow tier), to 45.6% under strong restrictions (red tier). Higher restrictions levels were also found to increase the relative contribution of contacts occurring within the household. The SARS-CoV-2 reproduction number was estimated to decrease by 18.7% (95%CI: 4.6-30.8), 33.4% (95%CI: 22.7-43.2), and 50.2% (95%CI: 40.9-57.7) under the yellow, orange, and red tiers, respectively.ConclusionsOur results give an important quantification of the expected contribution of different restriction levels in shaping social contacts and decreasing the transmission potential of SARS-CoV-2. These estimates can find an operational use in anticipating the effect that the implementation of these tiered restriction can have on SARS-CoV-2 reproduction number under an evolving epidemiological situation.
- Published
- 2021
48. Mathematical modeling of COVID-19 in British Columbia: An age-structured model with time-dependent contact rates
- Author
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Naveed Z. Janjua, Daniel Coombs, Caroline Colijn, Prince A. Adu, Michael A. Irvine, Michael Otterstatter, Michelle Spencer, Marsha Taylor, Rebeca Cardim Falc atildeo, Notice Ringa, and Sarafa A. Iyaniwura
- Subjects
education.field_of_study ,Mathematical model ,Coronavirus disease 2019 (COVID-19) ,British Columbia ,Epidemiology ,Population ,Public Health, Environmental and Occupational Health ,COVID-19 ,Bayes Theorem ,Models, Theoretical ,Bayesian inference ,Microbiology ,Infectious Diseases ,Transmission (telecommunications) ,Mixing patterns ,Virology ,Econometrics ,Humans ,Parasitology ,education ,Age structured ,Mixing (physics) ,Mathematics - Abstract
Following the emergence of COVID-19 at the end of 2019, several mathematical models have been developed to study the transmission dynamics of this disease. Many of these models assume homogeneous mixing in the underlying population. However, contact rates and mixing patterns can vary dramatically among individuals depending on their age and activity level. Variation in contact rates among age groups and over time can significantly impact how well a model captures observed trends. To properly model the age-dependent dynamics of COVID-19 and understand the impacts of interventions, it is essential to consider heterogeneity arising from contact rates and mixing patterns. We developed an age-structured model that incorporates time-varying contact rates and population mixing computed from the ongoing BC Mix COVID-19 survey to study transmission dynamics of COVID-19 in British Columbia (BC), Canada. Using a Bayesian inference framework, we fit four versions of our model to weekly reported cases of COVID-19 in BC, with each version allowing different assumptions of contact rates. We show that in addition to incorporating age-specific contact rates and mixing patterns, time-dependent (weekly) contact rates are needed to adequately capture the observed transmission dynamics of COVID-19. Our approach provides a framework for explicitly including empirical contact rates in a transmission model, which removes the need to otherwise model the impact of many non-pharmaceutical interventions. Further, this approach allows projection of future cases based on clear assumptions of age-specific contact rates, as opposed to less tractable assumptions regarding transmission rates.
- Published
- 2021
49. SOCRATES-CoMix: a platform for timely and open-source contact mixing data during and in between COVID-19 surges and interventions in over 20 European countries
- Subjects
Europe ,Mathematical modelling ,Social contact behaviour ,SARS-CoV-2 ,Mixing patterns ,COVID-19 ,Contact data - Published
- 2021
50. Social Network Mixing Patterns In Mergers & Acquisitions - A Simulation Experiment
- Author
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Robert Fabac, Markus Schatten, and Tomislav Đuričin
- Subjects
mergers & acquisition ,social network analysis ,mixing patterns ,assortativity ,organizational design ,Business ,HF5001-6182 - Abstract
In the contemporary world of global business and continuously growing competition, organizations tend to use mergers and acquisitions to enforce their position on the market. The future organization’s design is a critical success factor in such undertakings. The field of social network analysis can enhance our uderstanding of these processes as it lets us reason about the development of networks, regardless of their origin. The analysis of mixing patterns is particularly useful as it provides an insight into how nodes in a network connect with each other. We hypothesize that organizational networks with compatible mixing patterns will be integrated more successfully. After conducting a simulation experiment, we suggest an integration model based on the analysis of network assortativity. The model can be a guideline for organizational integration, such as occurs in mergers and acquisitions.
- Published
- 2011
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