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Engineering educational research section Science Center for Engineering Education |
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KON Ryusuke
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Research Areas 【 display / non-display 】
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Natural Science / Applied mathematics and statistics
Papers 【 display / non-display 】
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Cross-diffusion predator–prey model derived from the dichotomy between two behavioral predator states Reviewed
Masato Iida, Hirofumi Izuhara, Ryusuke Kon
Discrete and Continuous Dynamical Systems - B 28 ( 12 ) 6159 - 6178 2023.12
Authorship：Last author Language：English Publishing type：Research paper (scientific journal)
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Invariant curves in a discrete-time two-species system Reviewed
Ryusuke Kon
Journal of Difference Equations and Applications 2023.11
Authorship：Lead author, Last author, Corresponding author Publishing type：Research paper (scientific journal) Publisher：Journal of Difference Equations and Applications
The dynamics of discrete-time two-species systems may not be simple even if they have no positive fixed points. To reveal the behaviour of such systems, we focus on a special class of discrete-time two-species systems whose degenerate cases have a line segment of positive fixed points. As a main result, we show that the line segment of positive fixed points persists as an invariant curve under a small perturbation of the degenerate case. The absence of a positive fixed point ensures that such an invariant curve consists of heteroclinic orbits connecting two axial fixed points. The general result is applied to a discrete-time competition model of Ricker type with reproductive delay. The application reveals the existence of heteroclinic orbits connecting two axial 2-cycles, not only heteroclinic orbits connecting two axial fixed points.
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Adaptive delayed reproduction in a 2-dimensional discrete-time competition model Reviewed
Ryusuke Kon
Journal of Biological Dynamics 17 ( 1 ) 2023.8
Authorship：Lead author, Last author, Corresponding author Publishing type：Research paper (scientific journal) Publisher：Journal of Biological Dynamics
This paper studies a 2-dimensional discrete-time competition model of Ricker type with reproductive delay. The model is examined under the assumption that species 1 and 2 have the same properties except that a fraction η of species 1 individuals delays the initiation of reproduction. This assumption ensures that species 1 is dominated by species 2 in the sense that species 2 is increasing whenever species 1 is increasing. It is shown that, even under this assumption, delayed reproduction can be adaptive, i.e. species 1 can invade the monoculture system of species 2 while species 2 cannot invade the monoculture system of species 1, if the population is fluctuating. The result is obtained by analytically examining the species invasibility at boundary 2-cycles, whose coordinates can be estimated by assuming (Formula presented.).
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Stability of Rosenzweig–MacArthur models with non-diffusive dispersal on non-regular networks Reviewed International coauthorship
Ryusuke Kon and Dinesh Kumar
Theoretical Population Biology 150 14 - 22 2023.4
Authorship：Lead author, Corresponding author Language：English Publishing type：Research paper (scientific journal)
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A Mathematical Model for Transmission of Hantavirus among Rodents and Its Effect on the Number of Infected Humans Reviewed International coauthorship
Supriatna A.K., Napitupulu H., Ndii M.Z., Ghosh B., Kon R.
Computational and Mathematical Methods in Medicine 2023 2023
Authorship：Last author Publishing type：Research paper (scientific journal) Publisher：Computational and Mathematical Methods in Medicine
In this paper, we present a mathematical model for the transmission of hantavirus among rodents and its effect on the number of hantavirus-infected human population. We investigate the model and present a standard analysis in mathematical epidemiology, such as determining the equilibria of the system and their stability analysis, together with the relationship to the basic reproduction number. It is found that the endemic equilibrium exists and is locally asymptotically stable when the basic reproduction number is greater than one; otherwise, the disease-free equilibrium is stable. Later on, we also show that by constructing a suitable Lyapunov function, the endemic equilibrium is globally asymptotically stable whenever it exists. Based on the basic reproduction number, we present a critical level of intervention to control the spread of the disease to humans. We found a significant finding from the present model that if the basic reproduction number is greater than one, then it is impossible to completely eliminate hantavirus disease in the system by solely focusing on any intervention for humans, like vaccination and curative action, without paying any attention to interventions for rodent populations. However, we can still decrease the density of infected humans with those interventions. Hence, we suggest that a combination of several interventions is needed to obtain effective control in eliminating the hantavirus. This information is useful for further study in finding an optimal control strategy to reduce or eliminate the transmission of hantavirus to humans.
DOI： 10.1155/2023/9578283
Books 【 display / non-display 】
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常微分方程式とロトカ・ヴォルテラ方程式 = Ordinary differential equations and Lotka‐Volterra equations
今 隆助, 竹内 康博（ Role： Joint author）
共立出版 2018.10
Language：Japanese Book type：Textbook, survey, introduction
MISC 【 display / non-display 】
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第31回日本数理生物学会大会報告
飯田雅人，今隆助，出原浩史
日本数理生物学会ニュースレター ( 96 ) 2 - 5 2022.2
Publishing type：Meeting report
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私とロトカ・ヴォルテラ方程式 Invited
今 隆助
日本数理生物学会ニュースレター ( 86 ) 2 - 9 2018.9
Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (scientific journal)
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Network structures and permanence of Lotka-Volterra equations
Ryusuke Kon
The Japanese Society for Mathematical Biology - Newsletter 58 72 - 77 2009.5
Language：Japanese Publishing type：Research paper, summary (national, other academic conference) Publisher：The Japanese Society for Mathematical Biology
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Mathematics on Permanence and Extinction
Yasuhiro Takeuchi, Ryusuke Kon, Yasuhisa Saito, Kazunori Sato
Bulletin of the Japan Society for Industrial and Applied Mathnematics 16 ( 4 ) 280 - 292 2006.12
Language：Japanese Publishing type：Research paper, summary (national, other academic conference)
Presentations 【 display / non-display 】
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単純な離散時間競争モデルにおける適応的な繁殖遅延
今 隆助
2023年度日本数理生物学会年会 2023.9
Event date： 2023.9.4 - 2023.9.6
Language：Japanese Presentation type：Oral presentation (general)
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A discrete-time competition model of Ricker type with reproductive delay International conference
Ryusuke Kon
The 10th International Congress on Industrial and Applied Mathematics (ICIM2023)) 2023.8
Event date： 2023.8.20 - 2023.8.25
Language：English Presentation type：Oral presentation (general)
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Dynamics of a discrete-time competition model of Ricker type with reproductive delay Invited International conference
Ryusuke Kon
The 28th International Conference on Difference Equations and Applications (ICDEA 2023) 2023.7
Event date： 2023.7.17 - 2023.7.21
Language：English Presentation type：Oral presentation (general)
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単純な離散時間競争モデルにおける適応的な繁殖遅延 Invited
今 隆助
日本人口学会第75回研究大会 2023.6
Event date： 2023.6.10 - 2023.6.11
Language：Japanese Presentation type：Oral presentation (general)
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Dynamics of a discrete-time competition model of Ricker type with reproductive delay International conference
Ryusuke Kon
Progress on Difference Equations (PODE2023) 2023.5
Event date： 2023.5.29 - 2023.5.31
Language：English Presentation type：Oral presentation (general)
Awards 【 display / non-display 】
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日本数理生物学会研究奨励賞
2007.7 日本数理生物学会
今 隆助
Award type：Award from Japanese society, conference, symposium, etc. Country：Japan
Grant-in-Aid for Scientific Research 【 display / non-display 】
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構造化生態系モデルのパーマネンス
Grant number：20K03735 2020.04 - 2024.03
独立行政法人日本学術振興会 科学研究費補助金 基盤研究(C)
Authorship：Principal investigator
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常微分方程式で近似できる構造化生態系モデルの数理的研究
2016.04 - 2021.03
科学研究費補助金 基盤研究(C)
Authorship：Principal investigator
昆虫の大発生や絶滅のような，自然界の個体数変動のパターンを説明するための理論を構築することは，生態学における重要な目標の一つである．これまで生物の個体数変動のパターンを説明するために研究されてきた生態系モデルの多くは，種内構造を無視している．そのため，種内構造が個体数変動に決定的な影響を及ぼす場合には現象の本質を捉えることが出来ない．本研究では，種内構造を持つ生態系モデル（構造化生態系モデル）の研究を行う．具体的には，常微分方程式による近似を利用することにより，従来の構造化生態系モデルでは扱いが難しかった振動的な個体数変動に対しても応用可能な理論を構築し，振動的な個体数変動が関係してくる生態学の未解決問題の解決を目指す．
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Lotka-Volterra方程式を用いた構造化生態系モデルの数理的研究
2011.04 - 2013.03
科学研究費補助金 若手研究(スタートアップ)
Authorship：Principal investigator
Lotka-Volterra方程式を用いた構造化生態系モデルの数理的研究．
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Volterraの原理を満たさない生態系の力学系モデルのパーマネンスの研究
2006.04 - 2009.03
科学研究費補助金 特別研究員推奨費
Authorship：Principal investigator
Volterraの原理を満たさない生態系の力学系モデルのパーマネンスの研究．
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非ロトカ・ボルテラ型モデルのパーマネンスの研究
2005.04 - 2006.03
科学研究費補助金 若手研究(B)
Authorship：Principal investigator
非ロトカ・ボルテラ型モデルのパーマネンスの研究．