Ashok Krishnamurthy | Mount Royal University (original) (raw)

Papers by Ashok Krishnamurthy

We present a spatial variant of the time series susceptible-infectious-recovered (TSIR) stochasti... more We present a spatial variant of the time series susceptible-infectious-recovered (TSIR) stochastic population-based model to capture the spatial transmission dynamics of a measles outbreak across the landscape of England and Wales during the pre-vaccine era. Specifically, we explore how the basic dynamical features of a measles outbreak with a seasonal forcing of transmission acts as a major driver of a long-term epidemic behavior.

We use a 20-year pre-vaccination era biweekly time series data (births by year and incidence of measles for the years 1944-1966) from 60 towns and cities in England and Wales to capture the spatial spread of measles.

In England and Wales prior to vaccination, measles was endemic in large cities, but in smaller cities disease fadeout occurred. Reappearance of the disease would then occur only after a case was imported from a surrounding city where measles was endemic. To capture spatio-temporal dynamics, multi-city models must be developed, but these models can become very large requiring more memory and processing power than a single computer can deliver.

Rather than represent the population as a linked set of cities, we represent the population as a gridded map. Each grid cell can transmit infectious disease to its neighbors, with probabilities that decline exponentially with distance. We present a stochastic spatial model with six compartments. We call this the kids-susceptible-infectious-recovered-adults-dead (KSIRAD) model.

From the simulation, we recover spatiotemporal maps of the incidence of the infection. We compare simulated time-series graphs with real data compiled by Grenfell and others.

Our future work includes testing of our spatial model for measles outbreaks reported in the modern era, for example, in conflict affected areas of the Republic of the Niger in Western Africa in 2016. Socioeconomic disparities in a country like Niger presents significant challenges to reporting and real-time tracking of human infectious diseases.

Journal of midwifery & women's health, 2015

Research on health care provided to clients with limited English proficiency in the United States... more Research on health care provided to clients with limited English proficiency in the United States has revealed poor satisfaction and increased use of the health care system. This mixed-methods study explored health literacy and the perinatal experiences of Somali and Somali Bantu women living in Lewiston, Maine. The study also describes the development and validation of historietas (comic-book style health education brochure) used to increase knowledge and awareness of why emergency cesareans may be required and the symptoms of postpartum depression (PPD). During phase 1, a focus group to discuss the perinatal experiences of Somali women (n = 4) was undertaken and 2 historietas were developed to create greater understanding of emergency cesareans and PPD. In phase 2, Somali and Somali Bantu women (n = 19) completed a health literacy questionnaire and a perinatal experiences questionnaire. A focus group was also conducted during phase 2 to determine the perinatal experiences of the p...

The benefits of experiencing green space and nature experiences are increasingly being recognized... more The benefits of experiencing green space and nature experiences are increasingly being recognized and translated into policy and practice. Alongside this trend, inclusion of all people into parks and nature has been an important area of therapeutic recreation practice. Nature inclusion for those with disabilities, youth, seniors and immigrants has become a focus of Alberta Parks in collaboration with the Ministry of Tourism Parks and Recreation in Western Canada. This study was designed to examine the influence of two such government supported nature interventions, including day trips and a more extensive week-end or week-long nature experience, on mental well-being outcomes. A mixed methods pilot study (N=70) baseline and post intervention measures of quality of live using the standard Quality of Life Inventory alongside other qualitative accounts. In addition to the qualitative comments within the QOLI, qualitative data was elicited through reflective writing during the nature int...

Procedia computer …, Jan 1, 2010

In this major paper, we explore Boneh's Set-Covering (SC) equivalence technique for the classific... more In this major paper, we explore Boneh's Set-Covering (SC) equivalence technique for the classification of constraints in mathematical programmes as either redundant or necessary. At the core of Boneh's technique is a method for sampling in n-space and for each such point generating a binary row of a SC matrix, E p 0 , whose j th component is one if and only if the j th constraint is violated at that point. We describe a simple implementation of Boneh's technique that we refer to as the base method. The base method produces a redundancy free constraint matrix for a SC problem. Boneh has shown that any solution to the SC problem yields a constraint classification, which, in turn, yields a reduction of the constraint set.

Poster presented at the Statistical Society of Canada Conference - 2013

Proceedings of the Joint Statistical Meetings 2010

We explore the use of the optimal statistical interpolation (OSI) data assimilation method for th... more We explore the use of the optimal statistical interpolation (OSI) data assimilation method for the statistical tracking of emerging epidemics and to study the spatial dynamics of a disease. The epidemic models that we used for this study are spatial variants of the common susceptible-infectious-removed (S-I-R) compartmental model of epidemiology. The spatial S-I-R epidemic model is illustrated by application to simulated spatial dynamic epidemic data from the historic "Black Death" plague of 14th century Europe. Bayesian statistical tracking of emerging epidemic diseases using the OSI as it unfolds is illustrated for a simulated epidemic wave originating in Santa Fe, New Mexico.

We present a spatial variant of the time series susceptible-infectious-recovered (TSIR) stochasti... more We present a spatial variant of the time series susceptible-infectious-recovered (TSIR) stochastic population-based model to capture the spatial transmission dynamics of a measles outbreak across the landscape of England and Wales during the pre-vaccine era. Specifically, we explore how the basic dynamical features of a measles outbreak with a seasonal forcing of transmission acts as a major driver of a long-term epidemic behavior.

We use a 20-year pre-vaccination era biweekly time series data (births by year and incidence of measles for the years 1944-1966) from 60 towns and cities in England and Wales to capture the spatial spread of measles.

In England and Wales prior to vaccination, measles was endemic in large cities, but in smaller cities disease fadeout occurred. Reappearance of the disease would then occur only after a case was imported from a surrounding city where measles was endemic. To capture spatio-temporal dynamics, multi-city models must be developed, but these models can become very large requiring more memory and processing power than a single computer can deliver.

Rather than represent the population as a linked set of cities, we represent the population as a gridded map. Each grid cell can transmit infectious disease to its neighbors, with probabilities that decline exponentially with distance. We present a stochastic spatial model with six compartments. We call this the kids-susceptible-infectious-recovered-adults-dead (KSIRAD) model.

From the simulation, we recover spatiotemporal maps of the incidence of the infection. We compare simulated time-series graphs with real data compiled by Grenfell and others.

Our future work includes testing of our spatial model for measles outbreaks reported in the modern era, for example, in conflict affected areas of the Republic of the Niger in Western Africa in 2016. Socioeconomic disparities in a country like Niger presents significant challenges to reporting and real-time tracking of human infectious diseases.

Journal of midwifery & women's health, 2015

Research on health care provided to clients with limited English proficiency in the United States... more Research on health care provided to clients with limited English proficiency in the United States has revealed poor satisfaction and increased use of the health care system. This mixed-methods study explored health literacy and the perinatal experiences of Somali and Somali Bantu women living in Lewiston, Maine. The study also describes the development and validation of historietas (comic-book style health education brochure) used to increase knowledge and awareness of why emergency cesareans may be required and the symptoms of postpartum depression (PPD). During phase 1, a focus group to discuss the perinatal experiences of Somali women (n = 4) was undertaken and 2 historietas were developed to create greater understanding of emergency cesareans and PPD. In phase 2, Somali and Somali Bantu women (n = 19) completed a health literacy questionnaire and a perinatal experiences questionnaire. A focus group was also conducted during phase 2 to determine the perinatal experiences of the p...

The benefits of experiencing green space and nature experiences are increasingly being recognized... more The benefits of experiencing green space and nature experiences are increasingly being recognized and translated into policy and practice. Alongside this trend, inclusion of all people into parks and nature has been an important area of therapeutic recreation practice. Nature inclusion for those with disabilities, youth, seniors and immigrants has become a focus of Alberta Parks in collaboration with the Ministry of Tourism Parks and Recreation in Western Canada. This study was designed to examine the influence of two such government supported nature interventions, including day trips and a more extensive week-end or week-long nature experience, on mental well-being outcomes. A mixed methods pilot study (N=70) baseline and post intervention measures of quality of live using the standard Quality of Life Inventory alongside other qualitative accounts. In addition to the qualitative comments within the QOLI, qualitative data was elicited through reflective writing during the nature int...

Procedia computer …, Jan 1, 2010

In this major paper, we explore Boneh's Set-Covering (SC) equivalence technique for the classific... more In this major paper, we explore Boneh's Set-Covering (SC) equivalence technique for the classification of constraints in mathematical programmes as either redundant or necessary. At the core of Boneh's technique is a method for sampling in n-space and for each such point generating a binary row of a SC matrix, E p 0 , whose j th component is one if and only if the j th constraint is violated at that point. We describe a simple implementation of Boneh's technique that we refer to as the base method. The base method produces a redundancy free constraint matrix for a SC problem. Boneh has shown that any solution to the SC problem yields a constraint classification, which, in turn, yields a reduction of the constraint set.

Poster presented at the Statistical Society of Canada Conference - 2013

Proceedings of the Joint Statistical Meetings 2010

We explore the use of the optimal statistical interpolation (OSI) data assimilation method for th... more We explore the use of the optimal statistical interpolation (OSI) data assimilation method for the statistical tracking of emerging epidemics and to study the spatial dynamics of a disease. The epidemic models that we used for this study are spatial variants of the common susceptible-infectious-removed (S-I-R) compartmental model of epidemiology. The spatial S-I-R epidemic model is illustrated by application to simulated spatial dynamic epidemic data from the historic "Black Death" plague of 14th century Europe. Bayesian statistical tracking of emerging epidemic diseases using the OSI as it unfolds is illustrated for a simulated epidemic wave originating in Santa Fe, New Mexico.