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Strong competition model with non-uniform dispersal in a heterogeneous environment
Choi, Wonhyung,Ahn, Inkyung Elsevier 2019 APPLIED MATHEMATICS LETTERS Vol.88 No.-
<P><B>Abstract</B></P> <P>In this study, a strong competition model was considered between two species in a heterogeneous environment. For a system with two different constant diffusion rates for each competitor, the fast diffuser can be selected evolutionally under suitable assumptions if the competing interaction between the species is strong. We also claim that a strongly interacting competition leads to a more evolutionary selection than that with the same population dynamics if a species moves with a certain non-uniform dispersal. Furthermore, species with a certain non-uniform dispersal have a competitive advantage over linear random diffusers. In addition, a species with highly sensitive dispersal response to the environment may survive. These strongly competitive advantages were demonstrated by investigating the stability of semi-trivial solutions of the system with non-uniform dispersal and comparing it to the conditions of the model with constant diffusion.</P>
Choi, Wonhyung,Ahn, Inkyung Elsevier 2019 Journal of mathematical analysis and applications Vol.479 No.1
<P><B>Abstract</B></P> <P>In many cases, the movement of species within a region depends on the availability of food and other resources necessary for their survival. Starvation-driven diffusion (SDD) is a non-uniform dispersal strategy that increases the motility of biological organisms in unfavorable environments, i.e., a species moves more frequently in search of food if resources are insufficient . In this study, the proposed model represents the dispersion of an invasive species undergoing SDD, where the free boundary represents the expanding front. We observed that the spreading-vanishing dichotomy, which holds in the linear dispersal model, also holds in the model undergoing SDD. In the case that spreading of species occurs, it is shown that the asymptotic spreading speed of the moving front is uniquely determined in relation to the semi-wave speed. Moreover, our results are compared with the results of the linear dispersal model to investigate the advantages of this strategic dispersal with respect to survival in new environments, i.e., the conditions that allowed the species undergoing SDD to spread and the random diffusers to vanish are monitored.</P>
SeungHo Jung,WonHyung Kim,HyeJin Choi,MinHee Kang,JeongSeop Lee,JaeNam Bae,ChulEung Kim 대한신경정신의학회 2011 PSYCHIATRY INVESTIGATION Vol.8 No.1
Objective-There have been few long-term studies that have assessed factors influencing treatment discontinuation and long-term outcome of schizophrenia in Korea. The present study aimed to evaluate factors affecting treatment discontinuation and treatment outcome, after 10 years, in patients with schizophrenia. Methods-Among hospitalized patients between 1997 and 1999, 191 patients were given continuous follow-up service. We examined the clinical characteristics and outcome of patients who remained in treatment. Regression analyses were used to find any clinical factors affecting treatment discontinuation. Results-One hundred thirty-three patients (71.12%) discontinued the treatment. The treatment retention group contained more female patients, paranoid-type patients, patients who had shown self-harming behavior, patients receiving clozapine, and patients with good medication compliance. The recovery rate was 25%. However, 42.3% did not have gainful employment. Further, most patients couldn’t live independently. Conclusion-The results show the importance of gender, patient behavior, medication, and medication compliance in predicting treatment discontinuation in patients with schizophrenia.
Effects of antioxidants on the neuronal cell death
Park, Younjoo,Jeong, Wonhyung,Kang, Ju-Hee,Kim, Joo-Il,Chung, Soo Youn,Chung, Myeon Woo,Lim, Hwa-Kyung,Hwang, Onyou,Lee, Sun Hee,Choi, Ki Hwan 식품의약품안전청 2000 식품의약품안전청 연보 Vol.4 No.-
증추신경흥분꼭로 낭용피고 있는 methamphetamine(METH)은 doparnine 신경세포에서 dopandne유리를 증가시킴으로서 흥분작움, 약물의존성 등의 효과를 나타낼 뿐 아니라, dopamine 신경계에 작용하여 세포손상을 유도한다. dopamine 신경세포주인 CATH.a 세포배양을 이용한 지난해의 in uifro 연구결과 MEH에 의한 신경세포사는 apoptosis에 의한 것으로 산화성 스트레스가 관여하며, MEHfl의해 세폰밖으로 유리틴 dopamine의 산화에 의한 것으로 확인되었다. 본 실험에서는 항산화 효능을 가진 것으로 알려져 있는 물질 중 인삼의 성븐 중 하나인 ginsenos펀e Rbl, 록차의 성분인 opjgallocatechin g패ate 및 selenium, aminoguanidine과 JV-acetyl cysteine이 METH과 6-hy강oxydopamine(6-·OHDA)에 의한 신경세포독성에 보호효과를 가지는지 여부에 대하여 살펴보았다. ginsenoside Rbl의 전처치레 의하여 6-0딘DA 및 METH 투여에 의한 도파민 신경세포손상이 유의성 있게 감소되었듬을 착인하고, 녹차의 성분 중 하나인 (-)eP구allocatechin 토allate 처리에 의하여 금-OHDA에 의한 도_파민 신경세포손상이 통계적으로 유의성 있게 감소되었음을 착인하였다. iNO즈 inhibitor인 aminoguanidine이 UfETH 투여에 의한 신경세포손상을 감소시킨 결과를 얻어, METH에 의한 신경세포독성을 」:1해하는 ginsenoside Rbl의 효과가 nitric oxide 기전과 관련이 있는지 여부를 살펴럴았다. 그러나 끄nsenoside Rbl 투여가 UfETH에 의하여 증가되는 NO 유리 및 iNO를 발현 증가를 억제하지는 않f=것으로 관찰되었다. 이러한 결과는, 도파민신경세포에 대한 MEH 및 6-OHDA의 손상효과를 확인하고, finsenoside Rbl, catechins, selenium 등 천연물 유래성분과 aminoguanidine,rf-acetylcystelne이 이들 신경세포손상에 미치는 영향을 살펴보고 그 기전을 검토함으로써 도파민신경 기능장애 및 보호 기전연구의 기초자료를 제공할 수 있을 것으로 사료된다. The methamphetamine(METH) Is commonly abused for its rewarding effects, which are thought to result from dopamine release in the nucleus accumbens, and is amonoaminergic toxi(:ant that destroys dopamine terminals in uivo. Previous study from ourlaboratory showed dopamine-dependent oxidative stress was the initial event of METH-inducedneurotoxicity, by using an in uifro model of immortaEzed neuronal cetl tine, CATH.a(CNSadrenergic tyrosine hydroxylase(THf expressing). In the present study, effects of possibleantioxidants, ginsenoside Rbl, epigallocatechin 2allate, selenillm, ardnoguanidine and N-acetylcysteine were exarfed whether they have protective effort from neurotoxicity induced byafETH or 6-OHDA. Pretreatment of ginsenoside Rbl significantly reduced neurotoxicity inducedby METH and 6-OHDA. Epigallocatechin gallate also sigaificantly reduced 6-OHDA inducedneurotoldcy, whereas it did not show protective effect from TvfETH-induced toxicity in CATH.acelT- Pretreatment of aminoguanidine, a specific iNOS inhibitor, decreased cytotoxicity inducedby METH. Ginsenoside Rbl, however, Od not show any difference in METH-induced increasein iNOS nor it did affect nftric oxide release. Aminoguanidine itself also did not affect ftricoxide release nor a10s induction induced by afETH. These results suggest possible role ofginsenoside Rbl..3hd epigallocatechin gallate in protectiHg dopandnergic neurotoxicity induced byMETH or 6-OHDA and that more investigations should be done to claffy the involvement ofnitric oxide as a possible mechanism of ginsenoside Rbl against bfETH-induced nevrotoxirity.