An analysis of variations in the age structure of Fasciola hepatica populations in sheep

Parasitology ◽  
1982 ◽  
Vol 84 (1) ◽  
pp. 49-61 ◽  
Author(s):  
Gary Smith
Keyword(s):  
Mathematical Model ◽  
Mortality Rate ◽  
Age Structure ◽  
Distribution Curve ◽  
Fasciola Hepatica ◽  
Age Distribution ◽  
Parasite Population ◽  
Simple Mathematical Model ◽  
Age Classes

SUMMARYThe processes which govern the age structure of Fasciola hepatica populations in sheep were investigated by means of a simple mathematical model. The mortality of the metacercariae on the pasture was shown to be a factor of major importance. The mortality rate depends on the micro-climate that prevails at the pasture surface, and thus the age distribution curve of a population of flukes is also determined in part by the weather. This has important implications for the chemotherapy of fascioliasis: flukicides are not equally effective over the whole range of age-classes of parasite and so the factors which govern the age distribution curve of the parasite population within individual hosts ultimately determine the efficiency of chemotherapy.

scholarly journals Unreported cases for Age Dependent COVID-19 Outbreak in Japan

2020 ◽  
Author(s):  
Quentin Griette ◽  
Pierre Magal ◽  
Ousmane Seydi
Keyword(s):  
Mathematical Model ◽  
Age Structure ◽  
Early Stage ◽  
Structured Data ◽  
Computational Method ◽  
Mitigation Measures ◽  
Age Classes ◽  
The Social ◽  
Age Dependent ◽  
Age Structured

AbstractWe investigate the age structured data for the COVID-19 outbreak in Japan. We consider a mathematical model for the epidemic with unreported infectious patient with and without age structure. In particular, we build a new mathematical model and a new computational method to fit the data by using age classes dependent exponential growth at the early stage of the epidemic. This allows to take into account differences in the response of patients to the disease according to their age. This model also allows for a heterogeneous response of the population to the social distancing measures taken by the local government. We fit this model to the observed data and obtain a snapshot of the effective transmissions occurring inside the population at different times, which indicates where and among whom the disease propagates after the start of public mitigation measures.

POPULATION ATTRIBUTES OF BLUE GROUSE IN SOUTHWESTERN ALBERTA

1966 ◽  
Vol 44 (5) ◽  
pp. 799-814 ◽  
Author(s):  
D. A. Boag
Keyword(s):  
Mortality Rate ◽  
Adult Male ◽  
Age Distribution ◽  
Older Age ◽  
Home Ranges ◽  
Adult Males ◽  
Age Classes ◽  
Adult Females ◽  
Dendragapus Obscurus ◽  
Breeding Grounds

A population of blue grouse (Dendragapus obscurus) was studied over a 10-year period in southwestern Alberta. During this time a number of population attributes were documented. Density declined from a maximum of 47 adult males in 1955 to a minimum of 6 in 1964 on the 620-acre study area. Dispersion of adult male blue grouse on the breeding grounds was accomplished by establishing territories which averaged 1.5 ac. Adult females inhabited overlapping home ranges which averaged 43 ac in size. The age distribution among marked birds on the breeding grounds in May and June indicated 75% adult (2 years and older) and 25% subadult (1 year of age). Of the adults, approximately one-half were 2-year-olds with decreasing proportions in older age classes until none remained after they were 9 years old. Juveniles formed 40% of the fall population each year. The average hatch was 5.1 chicks per breeding female. Recruitment to the population has been inadequate to maintain numbers. Excessive mortality or dispersal rates must account for this. Minimum recorded loss of chicks during their first summer averaged 27%. Mortality rate of birds more than 1 year old averaged 56% per annum. Dispersal to other breeding ranges was recorded only in juvenile grouse.

scholarly journals Unreported Cases for Age Dependent COVID-19 Outbreak in Japan

Biology ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 132 ◽  
Author(s):  
Quentin Griette ◽  
Pierre Magal ◽  
Ousmane Seydi
Keyword(s):  
Mathematical Model ◽  
Age Structure ◽  
Early Stage ◽  
Structured Data ◽  
Computational Method ◽  
Mitigation Measures ◽  
Age Classes ◽  
The Social ◽  
Age Dependent ◽  
Age Structured

We investigate the age structured data for the COVID-19 outbreak in Japan. We consider a mathematical model for the epidemic with unreported infectious patient with and without age structure. In particular, we build a new mathematical model and a new computational method to fit the data by using age classes dependent exponential growth at the early stage of the epidemic. This allows to take into account differences in the response of patients to the disease according to their age. This model also allows for a heterogeneous response of the population to the social distancing measures taken by the local government. We fit this model to the observed data and obtain a snapshot of the effective transmissions occurring inside the population at different times, which indicates where and among whom the disease propagates after the start of public mitigation measures.

scholarly journals On estimating the age composition of the commercial catch of Northeast Arctic cod from a sample of clusters

2003 ◽  
Vol 60 (2) ◽  
pp. 297-303 ◽  
Author(s):  
Aanes Sondre ◽  
Michael Pennington
Keyword(s):  
Age Structure ◽  
Age Distribution ◽  
Significant Loss ◽  
Effective Sample Size ◽  
Commercial Fishing ◽  
Total Catch ◽  
Intracluster Correlation ◽  
Age Composition ◽  
Commercial Catch ◽  
Arctic Cod

Abstract Assessment of Northeast Arctic cod is based on estimates of the commercial catch in numbers at age. The age structure of the catch is estimated by sampling fish from commercial fishing trips. Although it is commonly assumed that a sample of individuals is a random sample from the population, fish sampled from the same trip (i.e. from a “cluster” of fish) tend to be more similar in age than those in the total catch. For Northeast Arctic cod, the intracluster correlation for age is positive, and therefore the effective sample size is much smaller than the number of fish aged. Given the number of fish aged, the precision of the estimated age distribution is rather low, and the number of fish aged from each trip could be reduced from approximately 85 to 20 without a significant loss in precision.

scholarly journals SIR Model for Dengue Disease with Effect of Dengue Vaccination

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Pratchaya Chanprasopchai ◽  
I. Ming Tang ◽  
Puntani Pongsumpun
Keyword(s):  
Mathematical Model ◽  
Mortality Rate ◽  
Dengue Virus ◽  
Numerical Solutions ◽  
Specific Treatment ◽  
Sir Model ◽  
Dengue Vaccine ◽  
Dengue Disease ◽  
Modelling Methods

The dengue disease is caused by dengue virus, and there is no specific treatment. The medical care by experienced physicians and nurses will save life and will lower the mortality rate. A dengue vaccine to control the disease is available in Thailand since late 2016. A mathematical model would be an important way to analyze the effects of the vaccination on the transmission of the disease. We have formulated an SIR (susceptible-infected-recovered) model of the transmission of the disease which includes the effect of vaccination and used standard dynamical modelling methods to analyze the effects. The equilibrium states and their stabilities are investigated. The trajectories of the numerical solutions plotted into the 2D planes and 3D spaces are presented. The main contribution is determining the role of dengue vaccination in the model. From the analysis, we find that there is a significant reduction in the total hospitalization time needed to treat the illness.

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