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<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" article-type="research-article" dtd-version="1.2" xml:lang="en"><front><journal-meta><journal-id journal-id-type="publisher-id">Contemporary Mathematics. Fundamental Directions</journal-id><journal-title-group><journal-title xml:lang="en">Contemporary Mathematics. Fundamental Directions</journal-title><trans-title-group xml:lang="ru"><trans-title>Современная математика. Фундаментальные направления</trans-title></trans-title-group></journal-title-group><issn publication-format="print">2413-3639</issn><issn publication-format="electronic">2949-0618</issn><publisher><publisher-name xml:lang="en">Peoples’ Friendship University of Russia named after Patrice Lumumba (RUDN University)</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="publisher-id">39910</article-id><article-id pub-id-type="doi">10.22363/2413-3639-2024-70-2-253-277</article-id><article-id pub-id-type="edn">YJBKWV</article-id><article-categories><subj-group subj-group-type="toc-heading" xml:lang="en"><subject>Articles</subject></subj-group><subj-group subj-group-type="toc-heading" xml:lang="ru"><subject>Статьи</subject></subj-group><subj-group subj-group-type="article-type"><subject>Research Article</subject></subj-group></article-categories><title-group><article-title xml:lang="en">Class of Keller-Segel chemotactic systems based on Einstein method of Brownian motion modeling</article-title><trans-title-group xml:lang="ru"><trans-title>Хемотаксические системы Келлера-Сегеля, основанные на модели броуновского движения Эйнштейна</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author"><name-alternatives><name xml:lang="en"><surname>Islam</surname><given-names>R.</given-names></name><name xml:lang="ru"><surname>Ислам</surname><given-names>Р.</given-names></name></name-alternatives><email>akif.ibraguimov@ttu.edu</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><name-alternatives><name xml:lang="en"><surname>Ibragimov</surname><given-names>A.</given-names></name><name xml:lang="ru"><surname>Ибрагимов</surname><given-names>А.</given-names></name></name-alternatives><email>akif.ibraguimov@ttu.edu</email><xref ref-type="aff" rid="aff1"/><xref ref-type="aff" rid="aff2"/></contrib></contrib-group><aff-alternatives id="aff1"><aff><institution xml:lang="en">Texas Tech University</institution></aff><aff><institution xml:lang="ru">Техасский технологический университет</institution></aff></aff-alternatives><aff-alternatives id="aff2"><aff><institution xml:lang="en">Institute of Oil and Gas Problems of the RAS</institution></aff><aff><institution xml:lang="ru">Институт проблем нефти и газа РАН</institution></aff></aff-alternatives><pub-date date-type="pub" iso-8601-date="2024-06-30" publication-format="electronic"><day>30</day><month>06</month><year>2024</year></pub-date><volume>70</volume><issue>2</issue><issue-title xml:lang="en">Functional spaces. Differential operators. Problems of mathematics education</issue-title><issue-title xml:lang="ru">Функциональные пространства. Дифференциальные операторы. Проблемы математического образования</issue-title><fpage>253</fpage><lpage>277</lpage><history><date date-type="received" iso-8601-date="2024-07-08"><day>08</day><month>07</month><year>2024</year></date></history><permissions><copyright-statement xml:lang="en">Copyright ©; 2024, Islam R., Ibragimov A.</copyright-statement><copyright-statement xml:lang="ru">Copyright ©; 2024, Ислам Р., Ибрагимов А.</copyright-statement><copyright-year>2024</copyright-year><copyright-holder xml:lang="en">Islam R., Ibragimov A.</copyright-holder><copyright-holder xml:lang="ru">Ислам Р., Ибрагимов А.</copyright-holder><ali:free_to_read xmlns:ali="http://www.niso.org/schemas/ali/1.0/"/><license><ali:license_ref xmlns:ali="http://www.niso.org/schemas/ali/1.0/">https://creativecommons.org/licenses/by-nc/4.0</ali:license_ref></license></permissions><self-uri xlink:href="https://journals.rudn.ru/CMFD/article/view/39910">https://journals.rudn.ru/CMFD/article/view/39910</self-uri><abstract xml:lang="en"><p style="text-align: justify;">We study the movement of the living organism in a band form towards the presence of chemical substrates based on a system of partial differential evolution equations. We incorporate Einstein’s method of Brownian motion to deduce the chemotactic model exhibiting a traveling band. It is the first time that Einstein’s method has been used to motivate equations describing the mutual interaction of the chemotactic system. We have shown that in the presence of limited and unlimited substrate, traveling bands are achievable and it has been explained accordingly. We also study the stability of the constant steady states for the system. The linearized system about a constant steady state is obtained under the mixed Dirichlet and Neumann boundary conditions. We are able to find explicit conditions for linear instability. The linear stability is established with respect to the L<sup>2</sup>-norm, H<sup>1</sup>-norm, and L<sup>∞</sup>-norm under certain conditions.</p></abstract><trans-abstract xml:lang="ru"><p style="text-align: justify;">Изучается движение живого организма ленточной формы в направлении концентрации химических субстратов с помощью системы эволюционных дифференциальных уравнений в частных производных. Используется метод броуновского движения Эйнштейна для вывода хемотаксической модели, демонстрирующей бегущую полосу. Впервые применен метод Эйнштейна для обоснования уравнений, описывающих взаимодействие хемотаксической системы. Показано, что при наличии как ограниченного, так и неограниченного субстрата возможны бегущие полосы, и это соответствующим образом обосновано. Также изучается устойчивость постоянных стационарных состояний системы. Линеаризованная система в окрестности постоянного стационарного состояния получена при смешанных граничных условиях Дирихле и Неймана. Нам удалось найти явные условия линейной неустойчивости. Установлена линейная устойчивость по L<sup>2</sup>-норме, H<sup>1</sup>-норме и L<sup>∞</sup>-норме при определенных условиях.</p></trans-abstract><kwd-group xml:lang="en"><kwd>chemotactic model</kwd><kwd>Einstein’s method of Brownian motion</kwd><kwd>traveling band</kwd></kwd-group><kwd-group xml:lang="ru"><kwd>хемотаксическая модель</kwd><kwd>метод броуновского движения Эйнштейна</kwd><kwd>бегущая полоса</kwd></kwd-group><funding-group><funding-statement xml:lang="en">The research was supported by the state assignment of the Institute of Oil and Gas Problems of the RAS, project 122022800272-4.</funding-statement><funding-statement xml:lang="ru">Исследования поддержаны госзаданием Института проблем нефти и газа РАН, проект 122022800272-4.</funding-statement></funding-group></article-meta></front><body></body><back><ref-list><ref id="B1"><label>1.</label><mixed-citation>Adler J. 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