| Project/Area Number |
15540108
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General mathematics (including Probability theory/Statistical mathematics)
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| Research Institution | The University of Tokyo |
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Principal Investigator |
INABA Hisashi The University of Tokyo, Graduate School of Mathematical Sciences, Associate Professor, 大学院数理科学研究科, 助教授 (80282531)
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| Project Period (FY) |
2003 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2005: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2004: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2003: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | infectious diseases / population / basic reproduction number / threshold phenomena / mathematical model / age structure / SIR model / epidemic model / 感染症モデル / 安定人ロモデル / サバイバルモデル / 閾値定理 / 分岐 / HIV / AIDS / 構造化個体群モデル / AIDSの流行モデル / シャガス病 / 感染症流行モデル / テンポ調整出生率 / 後退分岐 |
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| Research Abstract |
Our main concern in this research is mathematical analysis and model developments for structured population models in demography, epidemiology and theoretical biology. Main results are as follows:
[1] Chagas disease (American trypanosomiasis) is transmitted by the vector population and also by blood transfusion and characterized by the existence of the acute short duration stage and the long chronic stage. We have formulated the duration-dependent population model for the Chagas disease and examined the existence and stability of the steady state. Depending on parameter values, the backward bifurcation of the endemic steady stat e can occur, which is an important fact to be considered in the preventive policy.
[2] We consider an age-duration-structured population model for HIV infection in a homosexual community. W e have shown sufficient conditions for backward or forward bifurcation to occur when the basic reproduction ratio crosses the unity. We have given sufficient conditions for th
… More
e local stability of the endemic steady states.
[3] We have considered a SIR type epidemic model for the spread of horizontally and vertically transmitted infectious diseases in an age-structured population. We proved that an endemic steady state exists if and only if the basic reproduction ratio is grater than unity, while the disease-free steady state is globally asymptotically stable it is less than unity. We also show that the locally stable endemic steady states are forwardly bifurcated from the disease-free steady state when the basic reproduction number crosses the unity.
[4] We have studied mathematical structure of the SIR epidemic model for the spread of directly transmitted infectious diseases in age-structured host populations, in which the basic system is formulated as infinite-dimensional homogeneous dynamical systems. We consider the case that the host population is described by the stable population model and proved the linearized stability principle such that as far as we concern the asymptotic behavior of the basic system, it is sufficient to examine the normalized system induced by assuming that the host population has already attained the stable population. Less
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