46 research outputs found
Old and Young. Can they coexist?
The object of the study is semelparous species, i.e. those whose individuals reproduce only once in their life and die afterwards. Examples are annual and biennial plants, salmon, cicada. If reproduction is restricted to a short time interval during the year (in the spring) and the duration of life is fixed to, say, k years, the population of semelparous species is subdivided into year classes according to the year of birth (modulo k). Since individuals in different year classes have different age, they can compete for a shared resource. As a result of the competition one or several year classes can go extinct. We have following questions: when we should expect to find coexistence of year classes (as, e.g., in salmon) and when competitive exclusion (as in the periodical insects, e.g. cicada)? When does one year class tune the environmental conditions such that other year classes are driven to extinction? And when, on the other hand, can a missing year class invade successfully? We construct a discrete-time k-dimensional nonlinear matrix model and investigate its dynamics. The main dynamical states are the "coexistence" equilibrium, i.e. a steady state with all year classes present, and k-periodic points on invariant coordinate axes and (hyper-)planes, which correspond to the situation of one or several year classes missing. The coexistence equilibrium is unique, we construct a characteristic equation for it and perform local bifurcation analysis for k=2 and 3 (biennial and triennial species). Also, in these cases, we analyse the local stability of the k-periodic points. In other words we derive criteria for coexistence or competitive exclusion in terms of parameters such that impacts of different age classes on the environment and sensitivities to the environment.
One of the most interesting feature of the dynamics is the existence of so-called vertical bifurcations, i.e. highly degenerate bifurcations for which an invariant manifold filled with periodic points occurs in the phase space. These bifurcations can serve as a switch between coexistence and competitive exclusion, in other words the coexistence equilibrium becomes stable and the k-periodic points on the coordinate axes/planes become transversally unstable (or vice versa) for the same combinations of parameter values. Transversal (in)stability corresponds to directions transversal to the coordinate axes/planes. Conditions for a vertical bifurcation are when a certain circulant matrix becomes singular or a certain nonlinear circulant system becomes degenerate.
We discuss also internal stability of the k-periodic points on the axes. They corresponds to the situation when only one year class is present (and the other are missing). We call it Single Year Class (SYC) behaviour. The k-periodic points are fixed points of the k-iterate of the original map restricted to the axes or a SYC-map. A SYC-map is a composition of several functions of similar type. We construct various analytical and numerical bifurcaion diagrams corresponding to local and global stability of these fixed points.
In addition, we construct competition models of several age-structured populations to explain a well-known phenomenon of prime numbers in life cycle length of Magicicada. This species live 13 or 17 years and population consists of a single year class (a brood). Our explanation for this phenomenon is that the long-living cicada "do not want" to be in resonance with short-living (2-3 years) cicada
The state of prooxidant system in rats’ kidneys under alcoholic intoxication and its combination with light exposure
Although the negative effects of excessive alcohol consumption are generally known in the human population, drinking alcoholic beverages is prevalent in society. According to WHO, alcohol abuse contributes to three million deaths per year globally and millions of people’s disabilities and organ damage.
In modern life, the use of ethanol is often combined with the influence of other harmful factors, such as the violation of the light regime. A modern person is exposed to light almost all the time. Night shifts, flights, jet lag and active nightlife contribute to the disturbance of circadian rhythms. Normally, the biological rhythms are regulated by melatonin, which is known to be secreted in the dark. Even a slight lighting inhibits its synthesis. It has been shown that melatonin has a wide range of biological effects but its main feature is a powerful antioxidant action
Year class coexistence or competitive exclusion for strict biennials?
We consider a discrete time model of semelparous biennial pop-
ulation dynamics. Interactions between individuals are modelled
with the aid of an "environmental" variable I. The impact on and
the sensitivity to the environmental condition is age specific. The
main result is that competitive exclusion between the year classes
is possible as is their coexistence. For moderate values of the basic
reproduction ratio R0 there is a strict dichotomy: depending on
the other parameters we either find competitive exclusion or coexis-
tence. We characterize rather precisely the patterns of age specific
impact and sensitivity that lead to either of these outcomes
ОВЛАДЕНИЕ ИННОВАЦИОННЫМИ МЕТОДАМИ И ТЕХНОЛОГИЯМИ В ФОРМАТЕ КОМЛЕКСНОГО ПОДХОДА ПРИ ОБУЧЕНИИ ИНОСТРАННОМУ ЯЗЫКУ В ВЫСШИХ УЧЕБНЫХ ЗАВЕДЕНИЯХ НЕЛИНГВИСТИЧЕСКОГО ПРОФИЛЯ
У статті визначені поняття «інновація» та «інноваційні методи викладання», представлена узагальнююча характеристика інноваційних методів та технологій викладання іноземної мови у вищому закладі освіти немовного профілю. Зроблено акцент на необхідності впровадження комплексного підходу при використанні інноваційних методів викладання. Доведено ефективність використання новітніх технологій викладання іноземної мови у процесі навчання. Визначені особливості сучасної методики викладання іноземних мов, яка пропонує широкий вибір концепцій навчання, методів та технологій – як традиційних, так і новаторських. Запропоновано віддати перевагу тим або іншим методам в залежності від цілей навчання, контингенту студентів, тривалості та інтенсивності навчального курсу. Авторами статті проведено ретельний аналіз сучасних досліджень та публікацій щодо питання впровадження інноваційних підходів викладання іноземної мови у вищій школі та визначено актуальність дослідницьких завдань, які вимагають суттєвих змін в освітній системі. У статті вказується на необхідність оптимального співвідношення традицій та інновацій, комплексне поєднання різноманітних технологій та методів викладання іноземної мови, що вимагає використання комплексного підходу. Метою статті є обґрунтування доцільності використання комплексного підходу при запровадженні інноваційних методів та технологій викладання іноземних мов у вищих закладах освіти немовного профілю.The article defines the concepts of "innovation" and "innovative teaching methods", provides a generalized characteristic of innovative methods and technologies of teaching a foreign language at a higher education institution of the non-linguistic profile. The emphasis is given on the necessity of implementing an integrated approach when applying the innovative teaching methods. The efficiency of using the newest technologies of teaching a foreign language in the learning process has been proved. The features of modern teaching methods of foreign languages are defined, which offers a wide range of teaching concepts, methods and technologies - both traditional and innovative. It is suggested to give preference to one or another method depending on the purpose of studying, the student contingent, the duration and intensity of the training course. The authors of the article carried out a thorough analysis of contemporary research and publications regarding the problem of innovative approaches involved in teaching foreign languages at a higher school and identified the relevance of research tasks that require significant changes in the educational system. The article points to the need for an optimal balance of traditions and innovations, a comprehensive combination of various technologies and methods of teaching a foreign language, which requires the use of an integrated approach. The purpose of the article is to justify the expediency of using an integrated approach in applying the innovative methods and technologies of teaching foreign languages at higher education institutions of the non-formal profile.В статье определены понятия «инновация» и «инновационные методы преподавания», представлена обобщающая характеристика инновационных методов и технологий преподавания иностранного языка в высшем учебном заведении неязыкового профиля. Сделан акцент на необходимости внедрения комплексного подхода при использовании инновационных методов преподавания. Доказана эффективность использования новейших технологий преподавания иностранного языка в процессе обучения. Определены особенности современной методики преподавания иностранных языков, которая предлагает широкий выбор концепций обучения, методов и технологий - как традиционных, так и новаторских. Предложено отдать предпочтение тем или иным методам в зависимости от целей обучения, контингента студентов, продолжительности и интенсивности учебного курса. Авторами статьи проведен тщательный анализ современных исследований и публикаций по вопросу внедрения инновационных подходов преподавания иностранного языка в высшей школе и определены актуальность исследовательских задач, которые требуют существенных изменений в образовательной системе. В статье указывается на необходимость оптимального соотношения традиций и инноваций, комплексное сочетание различных технологий и методов преподавания иностранного языка, что требует использования комплексного подхода. Целью статьи является обоснование целесообразности использования комплексного подхода при внедрении инновационных методов и технологий преподавания иностранных языков в высших учебных заведениях неязыкового профиля
Optimization of the Androgenesis Method in the In Vitro Culture of Anteneson the Basis ofT. AestivumHybrids
This study aimed to examine the regularities of the regenerationprocesses of haploid plants, the dependence of in vitro microspore morphogenesis in anther culture on optimization factors, and their efficiency in F1 hybrids of T. aestivumof different ecological and geographicorigin. It was found that heterosis contributed to an increased yield of haploid chlorophyll-bearing regenerants from hybrids obtained from the crossing of parental forms with different responsiveness to androclinia. Results were obtained for the complex optimization of the androgenesis method for the in vitro anther culture of T. aestivum, in order to create diploidized haploid lines (DHL) regardless of the influence of the genotype. The agroecological properties for a complex of economically useful traits were also assessed. DHLs were created that combined high yield (5.1-6.8 t / ha) with lodging resistance (straw height – 60-80 cm) and consistently high grain quality; these were characterized by increased resistance to major leaf diseases in comparison with the standard variety in the conditions of the Central Economic Region of the Non-Black Earth Zone of the Russian Federation.
Keywords: spring soft wheat, androgenesis, embyroidogenesis, callusogenesis, diploidized haploids, in vitro, yield and qualit
Contemporary simulation-based teaching methods in biochemistry education: exploring possibilities for medical universities
Abstract. Modern education faces the challenge of teaching science in a way that students not only acquire theoretical knowledge but also develop practical skills necessary for their future professional endeavors. In medical education, simulation-based teaching methods stand out as an effective tool for achieving these goals. This article delves into contemporary simulation-based teaching methods in biological chemistry and their significance and possibilities for medical universities