scholarly journals The Discrete Time-Space SIR-SI Age-Structured Model for Leptospirosis

2018 ◽  
Vol 7 (4.30) ◽  
pp. 484
Author(s):  
Nor Azah Samat ◽  
Aznida Che Awang
Keyword(s):  
Discrete Time ◽  
Disease Transmission ◽  
Transition Rate ◽  
Age Groups ◽  
Future Application ◽  
Structured Model ◽  
Time Space ◽  
Age Structured ◽  
Age Structured Model ◽  
Transmission Models

The aim of this study is to introduce new discrete time-space SIR-SI age-structured disease transmission models for Leptospirosis disease. The term “age-structured” here refers to having two different age groups, which are children and adult. These models are important because it will later lead to a conclusion of whether children or adult have high risk of being infected by Leptospirosis disease. In this study, two types of SIR-SI age-structured models are introduced. These include models with and without the transition rate between age groups. The future application of these two models will be based on the availability of parameter value and Leptospirosis data.

scholarly journals Future scenarios for the SARS-CoV-2 epidemic in Switzerland: an age-structured model

F1000Research ◽  
2021 ◽  
Vol 9 ◽  
pp. 646
Author(s):  
Janne Estill ◽  
Plamenna Venkova-Marchevska ◽  
Maroussia Roelens ◽  
Erol Orel ◽  
Alexander Temerev ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Compartmental Model ◽  
Critical Level ◽  
Age Groups ◽  
Future Scenarios ◽  
Structured Model ◽  
Increased Risk ◽  
Age Structured ◽  
Age Structured Model

The recent lifting of COVID-19 related restrictions in Switzerland causes uncertainty about the future of the epidemic. We developed a compartmental model for SARS-CoV-2 transmission in Switzerland and projected the course of the epidemic until the end of year 2020 under various scenarios. The model was age-structured with three categories: children (0-17), adults (18-64) and seniors (65- years). Lifting all restrictions according to the plans disclosed by the Swiss federal authorities by mid-May resulted in a rapid rebound in the epidemic, with the peak expected in July. Measures equivalent to at least 76% reduction in all contacts were able to eradicate the epidemic; a 54% reduction in contacts could keep the intensive care unit occupancy under the critical level and delay the next wave until October. In scenarios where strong contact reductions were only applied in selected age groups, the epidemic could not be suppressed, resulting in an increased risk of a rebound in July, and another stronger wave in September. Future interventions need to cover all age groups to keep the SARS-CoV-2 epidemic under control.

scholarly journals Future scenarios for the SARS-CoV-2 epidemic in Switzerland: an age-structured model

2020 ◽  
Author(s):  
Janne Estill ◽  
Plamenna Venkova-Marchevska ◽  
Maroussia Roelens ◽  
Erol Orel ◽  
Alexander Temerev ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Compartmental Model ◽  
Critical Level ◽  
Age Groups ◽  
Future Scenarios ◽  
Structured Model ◽  
The Future ◽  
Age Structured ◽  
Age Structured Model

The recent lifting of COVID-19 related restrictions in Switzerland causes uncertainty about the future of the epidemic. We developed a compartmental model for SARS-CoV-2 transmission in Switzerland and projected the course of the epidemic until the end of year 2020 under various scenarios. The model was age-structured with three categories, children (0-17), adults (18-64) and seniors (65- years). Lifting all restrictions according to the plans disclosed by the Swiss federal authorities by mid-May resulted in a rapid rebound in the epidemic, with the peak expected in July. Measures equivalent to at least 90% reduction in all contacts were able to eradicate the epidemic; 56% reduction in contacts could keep the intensive care unit occupancy under the critical level, and delay the next wave until October. Scenarios where strong contact reductions were only applied in selected age groups could not suppress the epidemic, increasing the risk of a next wave in July, and another stronger wave in September. Future interventions need to cover all age groups to keep the SARS-CoV-2 epidemic under control.

scholarly journals Future scenarios for the SARS-CoV-2 epidemic in Switzerland: an age-structured model

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 646
Author(s):  
Janne Estill ◽  
Plamenna Venkova-Marchevska ◽  
Maroussia Roelens ◽  
Erol Orel ◽  
Alexander Temerev ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Compartmental Model ◽  
Critical Level ◽  
Age Groups ◽  
Future Scenarios ◽  
Structured Model ◽  
Increased Risk ◽  
Age Structured ◽  
Age Structured Model

The recent lifting of COVID-19 related restrictions in Switzerland causes uncertainty about the future of the epidemic. We developed a compartmental model for SARS-CoV-2 transmission in Switzerland and projected the course of the epidemic until the end of year 2020 under various scenarios. The model was age-structured with three categories: children (0-17), adults (18-64) and seniors (65- years). Lifting all restrictions according to the plans disclosed by the Swiss federal authorities by mid-May resulted in a rapid rebound in the epidemic, with the peak expected in July. Measures equivalent to at least 90% reduction in all contacts were able to eradicate the epidemic; a 56% reduction in contacts could keep the intensive care unit occupancy under the critical level and delay the next wave until October. In scenarios where strong contact reductions were only applied in selected age groups, the epidemic could not be suppressed, resulting in an increased risk of a rebound in July, and another stronger wave in September. Future interventions need to cover all age groups to keep the SARS-CoV-2 epidemic under control.

POTENTIAL YIELD OF A ROCK SHRIMP STOCK, SICYONIA PENICILLATA IN THE NORTHERN GULF OF CALIFORNIA

Crustaceana ◽  
1999 ◽  
Vol 72 (6) ◽  
pp. 581-590 ◽  
Author(s):  
Juana Lopez-Martinez ◽  
Edgar Alcantara-Razo ◽  
Sergio Hernandez-Vazquez ◽  
Ernesto Chavez
Keyword(s):  
Gulf Of California ◽  
Age Groups ◽  
Potential Yield ◽  
Natural Oscillations ◽  
Recruitment Pattern ◽  
Stock Recruitment ◽  
Age Structured ◽  
Stochastic Recruitment ◽  
Age Structured Model ◽  
Compensatory Effect

AbstractA stock of rock shrimp Sicyonia penicillata was assessed in a fishery recently opened at Bahoa Kino, Sonora, Mexico. An age-structured model with stochastic recruitment was developed, which considers growth rate, natural mortality, and fishing mortality by age. Age groups were followed year by year with a stock-recruitment Ricker function where the seasonal recruitment pattern was defined as well. Simulations might be interpreted as showing a stable population with four year cycles, reflecting a density-dependent process. In 1996, fishing intensity had an apparent compensatory effect on the stock, decreasing the amplitude of natural oscillations and maintaining the stock at a biomass level similar to the size observed in a condition of no exploitation. The stock was found currently underexploited. As a result of the seasonal accessibility and the age of first-catch fishing (adult shrimp), the stock might be capable to withstand high fishing pressure without being overexploited. Se evaluo una poblacion de camaron de roca Sicyonia penicillata, de una pesqueroa recientemente abierta en Bahoa Kino, Sonora, Mexico. Se desarrollo un modelo basado en la estructura por edades que considera reclutamiento estocastico, tasa de crecimiento, mortalidad natural y mortalidad por pesca por grupo de edad. Estos grupos de edad fueron determinados ano tras ano mediante la funcion de reclutamiento de Ricker, en los que tambien se definio el patron estacional de reclutamiento. Las simulaciones muestran una poblacion estable con ciclos de cuatro anos, que indican un proceso de densodependencia. En 1996, la intensidad de pesca tuvo un efecto compensatorio sobre la poblacion, reduciendo la amplitud de las oscilaciones naturales y manteniendo al stock en un nivel de biomasa similar al observado en la condicion sin explotacion. Se encontro que el recurso esta subexplotado. Como resultado de la accesibilidad estacional y de que la edad de primera captura corresponde a camaron adulto, el recurso soporta alta presion de pesca sin dar evidencias de sobreexplotacion.

An Age-Structured Model of Fish Population Enhancement

2002 ◽  
pp. 376-394
Author(s):  
Richard Langton ◽  
James Lindholm ◽  
James Wilson ◽  
Sally Sherman
Keyword(s):  
Fish Population ◽  
Structured Model ◽  
Age Structured ◽  
Age Structured Model
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