Background INTEROCC is a seven-country cohort study of occupational exposures and brain cancer ri... more Background INTEROCC is a seven-country cohort study of occupational exposures and brain cancer risk, including occupational exposure to electromagnetic fields (EMF). In the absence of data on individual exposures, a Job Exposure Matrix (JEM) may be used to construct likely exposure scenarios in occupational settings. This tool was constructed using statistical summaries of exposure to EMF for various occupational categories for a comparable group of workers. Methods In this study, we use the Canadian data from INTEROCC to determine the best EMF exposure surrogate/estimate from three appropriately chosen surrogates from the JEM, along with a fourth surrogate based on Berkson error adjustments obtained via numerical approximation of the likelihood function. In this article, we examine the case in which exposures are gamma-distributed for each occupation in the JEM, as an alternative to the log-normal exposure distribution considered in a previous study conducted by our research team. ...
ABSTRACT Government agencies and fact-checking websites have been combating the spread of falseho... more ABSTRACT Government agencies and fact-checking websites have been combating the spread of falsehoods on social media by issuing correction messages. There has been, however, no research on the effectiveness of correction messages on falsehoods and their dynamic interaction. We develop a theoretical model of the competition between falsehoods and correction messages on Twitter and show different interventions under which falsehoods could be hampered. Moreover, we use panel vector autoregressive models and machine learning techniques to empirically investigate the dynamic interactions between falsehoods and correction messages through a unique longitudinal dataset of 279,597 tweets. We find that correction messages cause an increase in the propagation of falsehoods on social media if their use is not optimized. This study highlights the importance of having government agencies, fact-checking websites, and social media platforms work together to optimize effective correction messages. We argue such an effort will counter the spread of falsehoods.
In this talk, I am going to present a mathematical model of vaccine acceptance based on evolution... more In this talk, I am going to present a mathematical model of vaccine acceptance based on evolutionary game theory and disease modeling in which parents choose between vaccination and non-vaccination strategies by comparing their payoffs which involve perceived probability of infection and risk of vaccination. By incorporating social norms into the model, we found that it better fits pertussis vaccination rate and incidence data of the UK in 1967-2010, a period that has witnessed the DTP vaccine scare. Contrary to previous models, our model explains the widely observed phenomenon of attaining high levels of vaccine uptake in voluntary vaccination campaigns. Further model analyses and simulations reveal interesting dynamical behaviors of the ODE system depicting the vaccination behavior and disease incidence, e.g. exhibition of bi-stability regions. That bi-stability reveals that, depending on the context, social norms can either support or hinder immunization goals. This talk is based...
Chronic wasting disease (CWD) is a spongiform encephalopathy disease caused by the transmission o... more Chronic wasting disease (CWD) is a spongiform encephalopathy disease caused by the transmission of infectious prion agents. CWD is a fatal disease that affects wild and farmed cervids in North America with few cases reported overseas. Social interaction of cervids, feeding practices by wildlife keepers and climate effects on the environmental carrying capacity all can affect CWD transmission in deer. Wildlife deer game hunting is economically important to the semi-arid South Texas region and is affected by climate change. In this paper, we model and investigate the effect of climate change on the spread of CWD using typical climate scenarios. We use a system of impulsive differential equations to depict the transmission of CWD between different age groups and gender of cervids. The carrying capacity and contact rates are assumed to depend on climate. Due to the polygamy of bucks, we use mating rates that depend on the number of bucks and does. We analyze the stability of the model a...
Supplementary data tml http://rspb.royalsocietypublishing.org/content/suppl/2014/02/06/rspb.2013.... more Supplementary data tml http://rspb.royalsocietypublishing.org/content/suppl/2014/02/06/rspb.2013.3172.DC1.h "Data Supplement" References http://rspb.royalsocietypublishing.org/content/281/1780/20133172.full.html#ref-list-1 This article cites 43 articles, 9 of which can be accessed free Subject collections (230 articles) health and disease and epidemiology Articles on similar topics can be found in the following collections Email alerting service here right-hand corner of the article or click Receive free email alerts when new articles cite this article sign up in the box at the top
The recent COVID-19 pandemic has caused significant societal impacts. Besides loss of life there ... more The recent COVID-19 pandemic has caused significant societal impacts. Besides loss of life there were large additional costs incurred by every country including the treatment of patients and costs to implement response plans. The pandemic resulted in major economic disruptions and stalled growth worldwide due to travel bans, lockdowns, social distancing, and non-essential business closures. Public health officials in almost every country implemented and encouraged Nonpharmaceutical Interventions (NPIs) such as contact tracing, social distancing, masks, and isolation. Human behavioral decision-making concerning social isolation was a major hindrance to the success in curbing the pandemic worldwide. In many developing countries individuals’ choices were motivated by the competing risk of losing jobs, and daily income. In this chapter we focus on human behavior concerning social isolation in the context of decision-making during the pandemic. We developed a conceptual framework and det...
Background: Kuwait had its first COVID-19 in late February, and until October 6, 2020 it recorded... more Background: Kuwait had its first COVID-19 in late February, and until October 6, 2020 it recorded 108,268 cases and 632 deaths. Despite implementing one of the strictest control measures-including a three-week complete lockdown, there was no sign of a declining epidemic curve. The objective of the current analyses is to determine, hypothetically, the optimal timing and duration of a full lockdown in Kuwait that would result in controlling new infections and lead to a substantial reduction in case hospitalizations. Methods: The analysis was conducted using a stochastic Continuous-Time Markov Chain (CTMC), eight state model that depicts the disease transmission and spread of SARS-CoV 2. Transmission of infection occurs between individuals through social contacts at home, in schools, at work, and during other communal activities. Results: The model shows that a lockdown 10 days before the epidemic peak for 90 days is optimal but a more realistic duration of 45 days can achieve about a ...
In a frequency selective slow-fading channel in a MIMO system, the channel matrix is of the form ... more In a frequency selective slow-fading channel in a MIMO system, the channel matrix is of the form of a block matrix. We propose a method to calculate the limit of the eigenvalue distribution of block matrices if the size of the blocks tends to infinity. We will also calculate the asymptotic eigenvalue distribution of $HH^*$, where the entries of $H$ are jointly Gaussian, with a correlation of the form $E[h_{pj}\bar h_{qk}]= \sum_{s=1}^t \Psi^{(s)}_{jk}\hat\Psi^{(s)}_{pq}$ (where $t$ is fixed and does not increase with the size of the matrix). We will use an operator-valued free probability approach to achieve this goal. Using this method, we derive a system of equations, which can be solved numerically to compute the desired eigenvalue distribution.
The relationship between socioeconomic development and environmental degradation measures such as... more The relationship between socioeconomic development and environmental degradation measures such as SO2, CO, and NOx emissions and deforestation has sometimes been claimed to follow an environmental Kuznets curve. However, in an era of globalization where the populations that experience economic benefits may be geographically distant from the populations that experience the resulting environmental degradation, it is not clear whether mechanisms which may have supported an environmental Kuznets curve (EKC) previously can still be relied upon. Game theory—the mathematical formalization of strategic interactions in groups of two or more—can be useful in such situations. Here we present a game theoretical framework for thinking about strategic dimensions of the EKC, wherein each agent is a population. The framework captures how economic activities can impact ecosystem services for one or both agents, depending on degree of globalization. We show how the EKC can give way to undesirable out...
Cross border situations complicate epidemiologic risk assessments in transboundary regions such a... more Cross border situations complicate epidemiologic risk assessments in transboundary regions such as the USMexico border. Countries have different health policies, mosquito control policies, and mosquito surveillance systems. We established a binational Aedes mosquito surveillance program in Reynosa, Tamaulipas, and McAllen, Texas by replicating a part of the Mexican Integrated Vector Monitoring System (IVMS) across the international border. The entomologic surveillance of the IVMSs is based on ova collection cups (ovitraps) and for the binational project, the surveillance protocol was modified to include an Autocidal Gravid Ovitrap (AGO) in the center of every city-block (100 m) distribution of four ovitraps. We measured the weekly abundance of Aedes eggs and adult females in 72 clusters (cluster = one AGO and four ovitraps) in Reynosa and 67 clusters in McAllen from Epidemiologic Week (EW) 17 to EW 36. The mean weekly egg counts were 34 and 22 in McAllen and Reynosa respectively. Th...
Background INTEROCC is a seven-country cohort study of occupational exposures and brain cancer ri... more Background INTEROCC is a seven-country cohort study of occupational exposures and brain cancer risk, including occupational exposure to electromagnetic fields (EMF). In the absence of data on individual exposures, a Job Exposure Matrix (JEM) may be used to construct likely exposure scenarios in occupational settings. This tool was constructed using statistical summaries of exposure to EMF for various occupational categories for a comparable group of workers. Methods In this study, we use the Canadian data from INTEROCC to determine the best EMF exposure surrogate/estimate from three appropriately chosen surrogates from the JEM, along with a fourth surrogate based on Berkson error adjustments obtained via numerical approximation of the likelihood function. In this article, we examine the case in which exposures are gamma-distributed for each occupation in the JEM, as an alternative to the log-normal exposure distribution considered in a previous study conducted by our research team. ...
ABSTRACT Government agencies and fact-checking websites have been combating the spread of falseho... more ABSTRACT Government agencies and fact-checking websites have been combating the spread of falsehoods on social media by issuing correction messages. There has been, however, no research on the effectiveness of correction messages on falsehoods and their dynamic interaction. We develop a theoretical model of the competition between falsehoods and correction messages on Twitter and show different interventions under which falsehoods could be hampered. Moreover, we use panel vector autoregressive models and machine learning techniques to empirically investigate the dynamic interactions between falsehoods and correction messages through a unique longitudinal dataset of 279,597 tweets. We find that correction messages cause an increase in the propagation of falsehoods on social media if their use is not optimized. This study highlights the importance of having government agencies, fact-checking websites, and social media platforms work together to optimize effective correction messages. We argue such an effort will counter the spread of falsehoods.
In this talk, I am going to present a mathematical model of vaccine acceptance based on evolution... more In this talk, I am going to present a mathematical model of vaccine acceptance based on evolutionary game theory and disease modeling in which parents choose between vaccination and non-vaccination strategies by comparing their payoffs which involve perceived probability of infection and risk of vaccination. By incorporating social norms into the model, we found that it better fits pertussis vaccination rate and incidence data of the UK in 1967-2010, a period that has witnessed the DTP vaccine scare. Contrary to previous models, our model explains the widely observed phenomenon of attaining high levels of vaccine uptake in voluntary vaccination campaigns. Further model analyses and simulations reveal interesting dynamical behaviors of the ODE system depicting the vaccination behavior and disease incidence, e.g. exhibition of bi-stability regions. That bi-stability reveals that, depending on the context, social norms can either support or hinder immunization goals. This talk is based...
Chronic wasting disease (CWD) is a spongiform encephalopathy disease caused by the transmission o... more Chronic wasting disease (CWD) is a spongiform encephalopathy disease caused by the transmission of infectious prion agents. CWD is a fatal disease that affects wild and farmed cervids in North America with few cases reported overseas. Social interaction of cervids, feeding practices by wildlife keepers and climate effects on the environmental carrying capacity all can affect CWD transmission in deer. Wildlife deer game hunting is economically important to the semi-arid South Texas region and is affected by climate change. In this paper, we model and investigate the effect of climate change on the spread of CWD using typical climate scenarios. We use a system of impulsive differential equations to depict the transmission of CWD between different age groups and gender of cervids. The carrying capacity and contact rates are assumed to depend on climate. Due to the polygamy of bucks, we use mating rates that depend on the number of bucks and does. We analyze the stability of the model a...
Supplementary data tml http://rspb.royalsocietypublishing.org/content/suppl/2014/02/06/rspb.2013.... more Supplementary data tml http://rspb.royalsocietypublishing.org/content/suppl/2014/02/06/rspb.2013.3172.DC1.h "Data Supplement" References http://rspb.royalsocietypublishing.org/content/281/1780/20133172.full.html#ref-list-1 This article cites 43 articles, 9 of which can be accessed free Subject collections (230 articles) health and disease and epidemiology Articles on similar topics can be found in the following collections Email alerting service here right-hand corner of the article or click Receive free email alerts when new articles cite this article sign up in the box at the top
The recent COVID-19 pandemic has caused significant societal impacts. Besides loss of life there ... more The recent COVID-19 pandemic has caused significant societal impacts. Besides loss of life there were large additional costs incurred by every country including the treatment of patients and costs to implement response plans. The pandemic resulted in major economic disruptions and stalled growth worldwide due to travel bans, lockdowns, social distancing, and non-essential business closures. Public health officials in almost every country implemented and encouraged Nonpharmaceutical Interventions (NPIs) such as contact tracing, social distancing, masks, and isolation. Human behavioral decision-making concerning social isolation was a major hindrance to the success in curbing the pandemic worldwide. In many developing countries individuals’ choices were motivated by the competing risk of losing jobs, and daily income. In this chapter we focus on human behavior concerning social isolation in the context of decision-making during the pandemic. We developed a conceptual framework and det...
Background: Kuwait had its first COVID-19 in late February, and until October 6, 2020 it recorded... more Background: Kuwait had its first COVID-19 in late February, and until October 6, 2020 it recorded 108,268 cases and 632 deaths. Despite implementing one of the strictest control measures-including a three-week complete lockdown, there was no sign of a declining epidemic curve. The objective of the current analyses is to determine, hypothetically, the optimal timing and duration of a full lockdown in Kuwait that would result in controlling new infections and lead to a substantial reduction in case hospitalizations. Methods: The analysis was conducted using a stochastic Continuous-Time Markov Chain (CTMC), eight state model that depicts the disease transmission and spread of SARS-CoV 2. Transmission of infection occurs between individuals through social contacts at home, in schools, at work, and during other communal activities. Results: The model shows that a lockdown 10 days before the epidemic peak for 90 days is optimal but a more realistic duration of 45 days can achieve about a ...
In a frequency selective slow-fading channel in a MIMO system, the channel matrix is of the form ... more In a frequency selective slow-fading channel in a MIMO system, the channel matrix is of the form of a block matrix. We propose a method to calculate the limit of the eigenvalue distribution of block matrices if the size of the blocks tends to infinity. We will also calculate the asymptotic eigenvalue distribution of $HH^*$, where the entries of $H$ are jointly Gaussian, with a correlation of the form $E[h_{pj}\bar h_{qk}]= \sum_{s=1}^t \Psi^{(s)}_{jk}\hat\Psi^{(s)}_{pq}$ (where $t$ is fixed and does not increase with the size of the matrix). We will use an operator-valued free probability approach to achieve this goal. Using this method, we derive a system of equations, which can be solved numerically to compute the desired eigenvalue distribution.
The relationship between socioeconomic development and environmental degradation measures such as... more The relationship between socioeconomic development and environmental degradation measures such as SO2, CO, and NOx emissions and deforestation has sometimes been claimed to follow an environmental Kuznets curve. However, in an era of globalization where the populations that experience economic benefits may be geographically distant from the populations that experience the resulting environmental degradation, it is not clear whether mechanisms which may have supported an environmental Kuznets curve (EKC) previously can still be relied upon. Game theory—the mathematical formalization of strategic interactions in groups of two or more—can be useful in such situations. Here we present a game theoretical framework for thinking about strategic dimensions of the EKC, wherein each agent is a population. The framework captures how economic activities can impact ecosystem services for one or both agents, depending on degree of globalization. We show how the EKC can give way to undesirable out...
Cross border situations complicate epidemiologic risk assessments in transboundary regions such a... more Cross border situations complicate epidemiologic risk assessments in transboundary regions such as the USMexico border. Countries have different health policies, mosquito control policies, and mosquito surveillance systems. We established a binational Aedes mosquito surveillance program in Reynosa, Tamaulipas, and McAllen, Texas by replicating a part of the Mexican Integrated Vector Monitoring System (IVMS) across the international border. The entomologic surveillance of the IVMSs is based on ova collection cups (ovitraps) and for the binational project, the surveillance protocol was modified to include an Autocidal Gravid Ovitrap (AGO) in the center of every city-block (100 m) distribution of four ovitraps. We measured the weekly abundance of Aedes eggs and adult females in 72 clusters (cluster = one AGO and four ovitraps) in Reynosa and 67 clusters in McAllen from Epidemiologic Week (EW) 17 to EW 36. The mean weekly egg counts were 34 and 22 in McAllen and Reynosa respectively. Th...
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