検索結果 1207 件
| JaLCDOI | 10.18926/fest/11510 |
|---|---|
| フルテキストURL | 007_001_005.pdf |
| 著者 | 大賀 潔生| 石川 洋文| 土井 陸雄| 石井 裕之| |
| 抄録 | In our study, we have investigated the influence of the intermediate host population density on the prevalence of Echinococcus multilocularis in the definitive host using a mathematical model of transmission. For the vole population (intermediate host) in Hokkaido, a model of population dynamics has been constructed in this paper which follows the seasonal and annual fluctuations. In the northeastern area, the vole density appears to fluctuate periodically with a 4 year cycle. The prevalence of Echinococcus multilocularis in the fox population (definitive host) can be affected by the density of vole through the fox ingesting infectious voles. Therefore we have prepared a food habit function of foxes and the logistic distribution has been proposed. The simulations which have been carried out using the mathematical model for transmission of Echinococcus multilocularis together with the vole dynamics have indicated that the prevalence in foxes is correlated and synchronized with the population dynamics of vole. In addition they have also made us recognize that it is necessary to introduce a suitable food habit function into the transmission model. |
| キーワード | Echinococcus multilocularis food habit of foxes Hokkaido population dynamics vole |
| 出版物タイトル | 岡山大学環境理工学部研究報告 |
| 発行日 | 2002-03-22 |
| 巻 | 7巻 |
| 号 | 1号 |
| 開始ページ | 1 |
| 終了ページ | 5 |
| ISSN | 1341-9099 |
| 言語 | 英語 |
| 論文のバージョン | publisher |
| JaLCDOI | 10.18926/fest/11487 |
|---|---|
| フルテキストURL | 008_001_007.pdf |
| 著者 | Tsunekuni Yasuhiro| Ohga Yukio| 石川 洋文| |
| 抄録 | In 1990s, there were rapid increases in the number of HIV epidemics and AIDS cases in Thailand, Southeast Asia. In particular the risk of HIV infection was very high among female prostitutes who played a large part in the transmission of HIV infection. We formulated a mathematical model for the transmission of HIV in prostitutes. We carried out the model simulations to analyze the incipient spread of HIV infection and the effect of AIDS prevention methods in prostitutes. The simulation of our model indicates that even if the effect of AIDS prevention methods such as the recommendation of condom use for commercial sex workers would block the transmission at rate by 70%, the elimination of the HIV epidemic is still beyond attainment. |
| キーワード | AIDS HIV prostitution Thailand transmission model |
| 出版物タイトル | 岡山大学環境理工学部研究報告 |
| 発行日 | 2003-03 |
| 巻 | 8巻 |
| 号 | 1号 |
| 開始ページ | 1 |
| 終了ページ | 7 |
| ISSN | 1341-9099 |
| 言語 | 英語 |
| 論文のバージョン | publisher |
| NAID | 120002314019 |
| JaLCDOI | 10.18926/fest/11481 |
|---|---|
| フルテキストURL | 010_009_011.pdf |
| 著者 | 梶原 毅| 佐々木 徹| |
| 抄録 | An elementary proof of permanence for a simple mathematical model proposed by Nowak and Bangham. In many papers, permanence property is proved by theorems established by the general theory of dynamical system. In this paper, we present an elementary proof only using differential inequalities and the theory of linear differential equations with constant coefficients. |
| キーワード | Permanence dynamical system pathogen |
| 出版物タイトル | 岡山大学環境理工学部研究報告 |
| 発行日 | 2005-02-28 |
| 巻 | 10巻 |
| 号 | 1号 |
| 開始ページ | 9 |
| 終了ページ | 11 |
| ISSN | 1341-9099 |
| 言語 | 英語 |
| 論文のバージョン | publisher |
| NAID | 120002313596 |
| JaLCDOI | 10.18926/fest/11455 |
|---|---|
| フルテキストURL | 009_045_051.pdf |
| 著者 | Iuchi Takuma| 梶原 毅| |
| 抄録 | Qualitative analysis for the model of HIV infection in vivo presented by Perelson and Nelson are developed. The local stability analysis is done for the interior equilibrium, and it is shown that, for some paramter value, the interior equilibrium can be unstable and a Hopf bifurcation can occur. It is shown that the boundary equilibrium is globally asymptotically stable. Last, it is shown that this system is permanent. |
| キーワード | HIV Mathematical model Stability Liapunov function |
| 出版物タイトル | 岡山大学環境理工学部研究報告 |
| 発行日 | 2004-02-27 |
| 巻 | 9巻 |
| 号 | 1号 |
| 開始ページ | 45 |
| 終了ページ | 51 |
| ISSN | 1341-9099 |
| 言語 | 英語 |
| 論文のバージョン | publisher |
| NAID | 120002313809 |
| JaLCDOI | 10.18926/fest/11425 |
|---|---|
| タイトル（別表記） | A mathematical model of Plasmodium falciparum transmission incorporating drug resistance: Simulations of the Solomon Islands situation |
| フルテキストURL | 012_019_027.pdf |
| 著者 | 陳 甜甜| 仁科 朝彦| 久兼 直人| 石川 洋文| |
| 抄録 | The Solomon Islands are known as a high endemic region of malaria. The resistance of Plasmodium falciparum to chloroquine has been confirmed since 1980 in the Solomon Islands, and the spread of chloroquine resistance is a big hurdle to malaria control. We have constructured the model for P. falciparum making allowance of chloroquine resistance. We distinguish the infection of resistance strains from that of sensitive strains in both the human and the vector populations. Since the overall parasite rate and the parasite rate of gametocytes for P. falciparum are strongly dependent on age, the human population is divided into 7 age groups in the model. The epidemiological parameters are determined by malariological survey in northeastern Guadalcanal (Ishii et al.) and the sporozoite rate in vector population is assumed as 0.1% based on the entomological study (Harada et al.) Our study aims at estimating the effect of mass drug administration under the presence of drug-resistance and also analyzing the escalation of drug-resistance through the transmission model for P. falciparum which can deal with chloroquine resistance. |
| キーワード | Solomon Islands Plasmodium falciparum drug resistance model |
| 出版物タイトル | 岡山大学環境理工学部研究報告 |
| 発行日 | 2007-03-15 |
| 巻 | 12巻 |
| 号 | 1号 |
| 開始ページ | 19 |
| 終了ページ | 27 |
| ISSN | 1341-9099 |
| 言語 | 日本語 |
| 論文のバージョン | publisher |
| NAID | 120002313858 |
| JaLCDOI | 10.18926/fest/11422 |
|---|---|
| フルテキストURL | 011_001_007.pdf |
| 著者 | Fujita Kazutoshi| Tian Tian Chen| Nishina Tomohiko| 石川 洋文| |
| 抄録 | Plasmodium vivax re-emerged in 1993 near the demilitarized zone (DMZ) in South Korea, although P. vivax malaria disappeared in South Korea in 1979. The re-emergence of malaria in South Korea is believed to have originated from infection by mosquitoes from North Korea across the DMZ. The principal vector of P. vivax in the Korean Peninsula is Anopheles sinensis. The density of An. sinensis has a peak during the second week of July. The North Korean strain of P. vivax has 2 characteristics: a wide distribution of the terms of relapse and a high rate of relapse. Therefore, we may well wonder why the incidence of malaria is concentrated in summer, especially in August. Mathematical models in North Korea and South Korea were constructed in which the South Korean model was affected unidirectionally by the North Korean model. We carried out simulations of the model for the Paju-shi and Yonchon-gun situations near the DMZ region. The simulation results followed the time-course of the re-emergence of P. vivax there, and revealed the mechanism of the elevation of the incidence of P. vivax in summer. |
| キーワード | DMZ Korea model Plasmodium vivax re-emergence |
| 出版物タイトル | 岡山大学環境理工学部研究報告 |
| 発行日 | 2006-03-15 |
| 巻 | 11巻 |
| 号 | 1号 |
| 開始ページ | 1 |
| 終了ページ | 7 |
| ISSN | 1341-9099 |
| 言語 | 英語 |
| 論文のバージョン | publisher |
| NAID | 40007297549 |
| JaLCDOI | 10.18926/fest/11421 |
|---|---|
| フルテキストURL | 012_001_006.pdf |
| 著者 | 渡邊 雅二| 河合 富佐子| |
| 抄録 | A mathematical model for exogenous depolymerization with time dependent degradation rate is analyzed in order to study the biodegradation of polyethylene glycol. The weight distribution with respect to the molecular weight before and after cultivation of microorganisms were analyzed an inverse problem to determine the time dependent degradation rate. Numerical techniques to solve the inverse problem and to simulate the transition of the weight distribution are described. |
| キーワード | biodegradation polyethylene glycol mathematical model numerical simulation |
| 出版物タイトル | 岡山大学環境理工学部研究報告 |
| 発行日 | 2007-03-15 |
| 巻 | 12巻 |
| 号 | 1号 |
| 開始ページ | 1 |
| 終了ページ | 6 |
| ISSN | 1341-9099 |
| 言語 | 英語 |
| 論文のバージョン | publisher |
| NAID | 120002313599 |