The Experts below are selected from a list of 623379 Experts worldwide ranked by ideXlab platform
Mark Jit - One of the best experts on this subject based on the ideXlab platform.
-
projecting social contact matrices in 152 countries using contact surveys and Demographic Data
PLOS Computational Biology, 2017Co-Authors: Kiesha Prem, Alex R Cook, Mark JitAbstract:Heterogeneities in contact networks have a major effect in determining whether a pathogen can become epidemic or persist at endemic levels. Epidemic models that determine which interventions can successfully prevent an outbreak need to account for social structure and mixing patterns. Contact patterns vary across age and locations (e.g. home, work, and school), and including them as predictors in transmission dynamic models of pathogens that spread socially will improve the models' realism. Data from population-based contact diaries in eight European countries from the POLYMOD study were projected to 144 other countries using a Bayesian hierarchical model that estimated the proclivity of age-and-location-specific contact patterns for the countries, using Markov chain Monte Carlo simulation. Household level Data from the Demographic and Health Surveys for nine lower-income countries and socio-Demographic factors from several on-line Databases for 152 countries were used to quantify similarity of countries to estimate contact patterns in the home, work, school and other locations for countries for which no contact Data are available, accounting for Demographic structure, household structure where known, and a variety of metrics including workforce participation and school enrolment. Contacts are highly assortative with age across all countries considered, but pronounced regional differences in the age-specific contacts at home were noticeable, with more inter-generational contacts in Asian countries than in other settings. Moreover, there were variations in contact patterns by location, with work-place contacts being least assortative. These variations led to differences in the effect of social distancing measures in an age structured epidemic model. Contacts have an important role in transmission dynamic models that use contact rates to characterize the spread of contact-transmissible diseases. This study provides estimates of mixing patterns for societies for which contact Data such as POLYMOD are not yet available.
Zuzana Munzbergova - One of the best experts on this subject based on the ideXlab platform.
-
how best to collect Demographic Data for population viability analysis models
Journal of Applied Ecology, 2005Co-Authors: Zuzana Munzbergova, Johan EhrlenAbstract:Summary 1. Matrix population models have become important tools in many fields of ecology and conservation biology, and are the most commonly used method in population viability analysis (PVA). There is a large literature concerned with different aspects of matrix model analysis, but relatively little attention has been paid to how Data are collected. 2. In most Demographic population viability studies, Data are sampled in permanent plots, often resulting in poor representation of some stages. It has been suggested that by using previous knowledge of species’ demography it is possible to sample Demographic Data more efficiently. Here we propose an alternative method that is much simpler and does not rely on any assumptions, namely sampling an equal number of individuals per stage. 3. By using Demographic Data from 32 species we showed that sampling an equal number of individuals per stage provides more precise estimates of both population growth rate and elasticity than the traditional plot-based method. In some cases it is also better than the estimates gained using the method based on previous knowledge of the species’ demography. The conclusions of the latter method are very sensitive to the quality of the previous knowledge of the species’ demography. In contrast, collecting Demographic Data from an equal number of individuals per stage is independent of any assumptions. 4. Synthesis and applications . A central aim for management of threatened species is to develop robust and accurate methods for assessing population viability that are also efficient in terms of costs and labour. A key issue is how to collect the Data on which viability assessments are based. We show that it is possible to increase considerably the accuracy and robustness of Demographic PVA without increasing sampling effort, by using a simple method based on sampling an equal number of individuals per life-cycle stage. Improved PVA model performance will be important to guide conservation efforts and to evaluate different management options.
Johan Ehrlen - One of the best experts on this subject based on the ideXlab platform.
-
how best to collect Demographic Data for population viability analysis models
Journal of Applied Ecology, 2005Co-Authors: Zuzana Munzbergova, Johan EhrlenAbstract:Summary 1. Matrix population models have become important tools in many fields of ecology and conservation biology, and are the most commonly used method in population viability analysis (PVA). There is a large literature concerned with different aspects of matrix model analysis, but relatively little attention has been paid to how Data are collected. 2. In most Demographic population viability studies, Data are sampled in permanent plots, often resulting in poor representation of some stages. It has been suggested that by using previous knowledge of species’ demography it is possible to sample Demographic Data more efficiently. Here we propose an alternative method that is much simpler and does not rely on any assumptions, namely sampling an equal number of individuals per stage. 3. By using Demographic Data from 32 species we showed that sampling an equal number of individuals per stage provides more precise estimates of both population growth rate and elasticity than the traditional plot-based method. In some cases it is also better than the estimates gained using the method based on previous knowledge of the species’ demography. The conclusions of the latter method are very sensitive to the quality of the previous knowledge of the species’ demography. In contrast, collecting Demographic Data from an equal number of individuals per stage is independent of any assumptions. 4. Synthesis and applications . A central aim for management of threatened species is to develop robust and accurate methods for assessing population viability that are also efficient in terms of costs and labour. A key issue is how to collect the Data on which viability assessments are based. We show that it is possible to increase considerably the accuracy and robustness of Demographic PVA without increasing sampling effort, by using a simple method based on sampling an equal number of individuals per life-cycle stage. Improved PVA model performance will be important to guide conservation efforts and to evaluate different management options.
Stefano Merler - One of the best experts on this subject based on the ideXlab platform.
-
Inferring the Structure of Social Contacts from Demographic Data in the Analysis of Infectious Diseases Spread
PLOS Computational Biology, 2012Co-Authors: Laura Fumanelli, Marco Ajelli, Piero Manfredi, Alessandro Vespignani, Stefano MerlerAbstract:Social contact patterns among individuals encode the transmission route of infectious diseases and are a key ingredient in the realistic characterization and modeling of epidemics. Unfortunately, the gathering of high quality experimental Data on contact patterns in human populations is a very difficult task even at the coarse level of mixing patterns among age groups. Here we propose an alternative route to the estimation of mixing patterns that relies on the construction of virtual populations parametrized with highly detailed census and Demographic Data. We present the modeling of the population of 26 European countries and the generation of the corresponding synthetic contact matrices among the population age groups. The method is validated by a detailed comparison with the matrices obtained in six European countries by the most extensive survey study on mixing patterns. The methodology presented here allows a large scale comparison of mixing patterns in Europe, highlighting general common features as well as country-specific differences. We find clear relations between epidemiologically relevant quantities (reproduction number and attack rate) and socio-Demographic characteristics of the populations, such as the average age of the population and the duration of primary school cycle. This study provides a numerical approach for the generation of human mixing patterns that can be used to improve the accuracy of mathematical models in the absence of specific experimental Data.
Brenda Rousset - One of the best experts on this subject based on the ideXlab platform.
-
trends in infant mortality in venezuela between 1985 and 2016 a systematic analysis of Demographic Data
The Lancet Global Health, 2019Co-Authors: Jenny Garcia, Gerardo Correa, Brenda RoussetAbstract:Summary Background Between the 1950s and 2000, Venezuela showed one of the most substantial improvements in infant mortality rates in Latin America. However, the recent economic crisis alongside an increase in infectious and parasitic diseases might be reversing previous patterns. Because no official updated mortality statistics have been published since 2013, the effect of these recent events has been difficult to assess accurately. We therefore aimed to estimate infant mortality rate trends and report the effect of the crisis. Methods We estimated infant mortality rates using direct methods (ie, death counts from Venezuelan Ministry of Health via yearbooks and notifiable diseases bulletins, and birth records published by the UN Economic Commission for Latin America and the Caribbean and the Venezuelan National Institute of Statistics) and indirect methods (using census Data and a Living Conditions Survey ENCOVI 2016). We shaped yearly estimations using a semiparametric regression model, specifically a P-Spline model with a cubic thin plate base. The primary objective was to estimate infant mortality rate trends from 1985 to 2016. Findings Around 2009, the long-term decline in infant mortality rate stopped, and a new pattern of increase was observed. The infant mortality rate reached 21·1 deaths per 1000 livebirths (90% CI −17·8 to 24·3) in 2016, almost 1·4 times the rate of 2008 (15·0, −14·0 to 16·1). This increase represents a huge setback on previous achievements in reducing infant mortality. Interpretation Our conservative estimation indicates that Venezuela is in the throes of a humanitarian crisis. The increase in infant mortality rate in 2016 compared with 2008 takes the country back to the level observed at the end of the 1990s, wiping out 18 years of expected progress, and leaves the Venezuelan Government far from achieving the target of nine deaths per 1000 livebirths stated in the UN Millennium Development Goals. Funding None.
