Temat: population dynamics

Skocz do pozycji: 1.

Tytuł:: Von Bertalanffys growth dynamics with strong Allee effect
Autorzy:: Rocha, J.
Aleixo, Sandra
Tematy:: Von Bertalanffy's model
population dynamics
Allee effect; Pokaż więcej
Wydawca:: Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Powiązania:: https://bibliotekanauki.pl/articles/729888.pdf Link otwiera się w nowym oknie
Opis:: Von Bertalanffy's model is one of the most popular differential equation used in order to study the increase in average length or weight of fish. However, this model does not include demographic Allee effect. This phenomenon is known in the fisheries literature as "depensation", which arises when populations decline rapidly at low densities. In this paper we develop and investigate new corrected von Bertalanffy's models with Allee effects. The generalization that we propose results from considering correction factors, one of rational type and the others of polynomial type, where two parameters are considered. The use of a parameter C > 0 leads the presented generalization, which yields some more flexible models with variable extinction rates. An Allee limit or unstable equilibrium $E^u$ is incorporated so that the models under study have strong Allee effect. We analyze and show the transition from the strong Allee effect to the inexistence of this effect, through by a "weakening" of the Allee effect, depending on the parameters C and $E^u$. Finally, we discuss the flexibility of corrected von Bertalanffy's sigmoid growth curves. So, the correspondents inflexion points are variable, i.e., the fish mass when the growth rate is maximum may be varied.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Badania nad liczebnością wyspowej populacji nornicy rudej (Clethrionomys glareolus, Schreber 1780) i ich znaczenie dla teorii
The population dynamics of bank voles (Clethrionomys glareolus, Schreber 1780) and its significance for theory
Autorzy:: Bujalska, Gabriela
Tematy:: Clethrionomys glareolus
nornica ruda
liczebność populacji
population dynamics; Pokaż więcej
Wydawca:: Uniwersytet Kardynała Stefana Wyszyńskiego w Warszawie
Powiązania:: https://bibliotekanauki.pl/articles/1817871.pdf Link otwiera się w nowym oknie
Opis:: This is an overview of long-term studies (1966-1997) on the bank vole - Clethrionomys glareolus (Photo 1). population inhabiting Crabapple Island in NE Poland. The history of recognition of causes affecting population dynamics as well as variable interpretation of the facts comprising the theory of functional relations in that population is described. Meandering ideas can be illustrated by Fig. 1. The population dynamics (each year data on population numbers in April, July, and October are shown) is presented in Fig. 2. The evidence is provided that the population exhibits a weak 3.8 year and a much more clear 9.4-year cycle (Fig. 3). The number of sexually mature females, that is those able to reproduce, has been relatively stable and independent of the population size or of the immature female numbers (Fig. 4). The reason is the territoriality of mature females: the female territory (part of the female home range) cannot be visited by other mature females. A tendency toward territoriality was also noted among mature males, which numbers were limited by the availability of mature females, and therefore also relatively stable. Such a social system can be considered gynocentric.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Field and Laboratory Studies of the Earthworm Dendrobaena Alpina
Autorzy:: Kostecka, J.
Butt, K. R.
Tematy:: earthworms
Dendrobaena alpina
field study
laboratory culture
population dynamics; Pokaż więcej
Wydawca:: Polskie Towarzystwo Inżynierii Ekologicznej
Powiązania:: https://bibliotekanauki.pl/articles/124743.pdf Link otwiera się w nowym oknie
Opis:: Distribution of Dendrobaena alpina covers the mountainous region of central Europe, where it has a high dominance and frequency index. This work describes data from field studies conducted over two annual cycles in the Bieszczady National Park (BNP), Poland, in different types of beech forest. Densities of this species ranged from 47–231 g·m ^-2 with associated biomasses of 19–90 g·m ^-2. Most (66%) were recovered from less than 0.1 m soil depth with a further 28% from up to 0.2 m. Further, the animals were collected alive from Lutowiska, close to the BNP to obtain baseline data on the life history of D. alpina. Mature individuals were kept in isolation and cocoon production monitored on a 2 monthly basis. Immature individuals were kept until they reached maturity, when they were paired, with combined output of cocoons regularly monitored. Cocoons were collected, had their masses determined and were incubated. Hatchability was recorded, as was estimated duration of incubation and growth to maturity. Field-collected adults had a mean mass of 1.4 g and at 15 ºC, these produced an average of 1.83 cocoons·worm ^-1·month ^-1. Zero cocoons were produced by further specimens, collected as immature, grown to maturity and maintained in isolation. Recently-matured, paired D. alpina produced an average of 1.65 cocoons·worm ^-1·month ^-3. Cocoons had a mean mass of 19 mg. At 15 ºC, cocoons produced by recently matured adults hatched after 80 days (82% viable), but after 2 months the majority of cocoons failed to hatch. Hatchling growth from an average of 18 mg to maturity required 7–11 months in the given substrate.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Changes in the aquatic moss Sphagnum denticulatum Brid. population abundance in a softwater lake over a period of three years
Autorzy:: Szmeja, J
Tematy:: aquatic moss
population dynamics
Sphagnum denticulatum
population abundance
soft water lake
lake
phenology; Pokaż więcej
Wydawca:: Polskie Towarzystwo Botaniczne
Powiązania:: https://bibliotekanauki.pl/articles/57078.pdf Link otwiera się w nowym oknie
Opis:: Changes in population abundance of submerged Sphagnum denticulatum Brid. were studied in an acidic and oligotrophic lake in NW Poland over three years. Individuals were counted in a moss carpet at a depth of 2.5 m on 4 experimental plots, 1 × 1 m each, every 30 days for 36 months using the SCUBA method. PAR intensity was seasonally variable (in winter higher than in summer). Changes in water pH, conductivity, HCO3- concentration, hydration and sediment pH were statistically insignificant (p > 0.05). In the summer of the second study year the moss carpet disappeared almost completely due to a massive bloom of filamentous green algae. Periods of growth, regression and regeneration were observed in the population. The stabilisation of population size took 24 months and followed the pattern: slight fluctuations, then rapid growth and repetition of slight fluctuations. The first stage lasted nine, the second four and the third nine months. These stages took place irrespective of seasons, temperature or PAR intensity. Each rapid increase in abundance lasted about 30 days, at PAR intensity >20% and water temperature ranging from 11 to 16oC (in winter, spring or autumn). The regression stage brought about by the algal bloom started in the second year (in summer) and lasted six months (until the end of January in the third year). The population regeneration began in winter (in February, water temperature 3.0oC, PAR about 20%, ice cover 0.15 m) and finished with the end of spring. The population of S. denticulatum shows a repetitive pattern of abundance variations, which is seriously disturbed in summer, especially after a warm spring, by a massive bloom of filamentous green algae.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Storage of hydrogenous gas in geological formations: self-organisation methane gas
Autorzy:: Toleukhanov, A.
Kaltayev, A.
Panfilov, M.
Tematy:: porous media
hydrogen
reactive transport
bacteria
neuston
chemotaxis
population dynamics
oscillations; Pokaż więcej
Wydawca:: Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Powiązania:: https://bibliotekanauki.pl/articles/298661.pdf Link otwiera się w nowym oknie
Opis:: In the case of producing large amounts of hydrogenous gas, currently there are no problems related to basic techniques of hydrogen production and distribution, but the main technological problem will consists of storing it in order to regulate the difference between permanent or increasing gas production and seasonally modulated gas consumption. The most efficient and most inexpensive method of storing large amounts of hydrogen is to inject them in geological formations like aquifers, depleted gas reservoirs, or salt caverns (Zittel and Wurster 1996). The cost is of order $ 3.5 per 1 GJ (Taylor et al. 1986). Several underground storages of hydrogen (USH) or town gas exist in the word, as for instance, Teeside in the UK, in Texas, in Russia, Kiel in Germany, Lobodice in Czechoslovakia, Beynes - an ex-storage in France. During several tens of years the storage of hydrogen was considered as something deja-vu, to be similar to that of natural gas, which is amplified by the chemical inactivity of hydrogen and its very low solvability in groundwater [Bulatov 1979; Carden and Paterson 1979; Lindblom 1985; Paterson 1983]. Nevertheless, quite unusual behaviour of UHS was discovered by in situ monitoring of the gas composition extracted during the cycle "production" which followed the cycle "injection". These observations (Smigai et al. 1990; Buzek et al. 1994) revealed high variations of gas composition in time and space. In particular, a significant reduction in the H2 and CO2 contents and a simultaneous increase in CH4 contents were observed in the Lobodice town gas storage facility (Smigai et al. 1990). Similar phenomena were recorded in Beynes. After several months of injection and storage, at the beginning of the cycle "production" the twofold increase of the methane contents in the reservoir gas and the twofold reduction of the CO2 CO contents was observed. The contents of hydrogen decreased by 1.4. The explanation to these observations has been done in (Buzek et al. 1994) in terms of the in situ methane generators by methanogenic bacteria which catalyse the reaction between hydrogen and CO2/CO, by producing methane and water. Further observations have revealed even more unusual effects within the storage facility, such as creating a spatial alternation of the areas saturated preferably by hydrogen or methane. This proved an in situ natural separation of chemical components in space. Thus, we are dealing with a natural reactor which partially destroys CO2 and H2 and doubles the mass of methane. It is clear that the problem is important for industry as it concerns both the energy sector and ecology. The resulting economical efficiency of such a process can be estimated only after the physical and mathematical modeling of all possible scenarios of the reservoir behaviour. The development of such a model represents the main objective of this paper.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: The dynamics of the population of a steppe perennial Senecio macrophyllus M.BIEB. during xerothermic grassland overgrowing
Autorzy:: Czarnecka, B
Tematy:: population dynamics
steppe plant
Senecio macrophyllus
xerothermic grassland
life-stage structure; Pokaż więcej
Wydawca:: Polskie Towarzystwo Botaniczne
Powiązania:: https://bibliotekanauki.pl/articles/56894.pdf Link otwiera się w nowym oknie
Opis:: The study aimed to determine the long-term changes of the Senecio macrophyllus M.BIEB. population traits: the abundance, reproduction mode, individual fecundity, seed rain and recruitment of new genets in the course of xerothermic grassland overgrowing. The study had also the applied goal: to estimate the chances of "special care" species to survive in the changing environment without management regime for the maintenance of grassland. The model object was the island population of large-leaved ragwort on Biała Góra (the White Mountain) near Tomaszów Lubelski, South-East Poland. To achieve these aims I used the following sets of data: phytosociological relev,s made in plant communities in an interval of 16-18 years; repeated elaboration of the numbers and life-stage structure of the population, both by non-surface and surface method; observation of plants, life cycle in 50 labelled genets; population reproduction and seed rain amounts. The area of an open xerothermic grassland decreased due to the process of overgrowing by bushes which was accompanied by the increasing coverage of forest and meadow herbs as well as monocotyledons, mainly Brachypodium pinnatum and Calamagrostis epigejos. The abundance of the S. macrophyllus population noticable diminished. The flowering mode has been changing during years from an oscillation to a chaotic type which caused the significant decreasing of the individual fecundity, population reproduction and seed rain. In last years it was reflected in the interruption of juveniles’ recruitment.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Dynamics of a two sex population with gestation period
Autorzy:: Busoni, Giorgio
Palczewski, Andrzej
Tematy:: differential equations with delay
stationary solutions
population dynamics
mathematical modelling; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Matematyczny PAN
Powiązania:: https://bibliotekanauki.pl/articles/1208215.pdf Link otwiera się w nowym oknie
Opis:: We investigate a mathematical model of population dynamics for a population of two sexes (male and female) in which new individuals are conceived in a process of mating between individuals of opposed sexes and their appearance is postponed by a period of gestation. The model is a system of two partial differential equations with delay which are additionally coupled by mathematically complicated boundary conditions. We show that this model has a global solution. We also analyze stationary ('permanent') solutions and show that such solutions exist if the model parameters satisfy two nonlinear relations.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Labor force dynamics and economic performance: A case of Nigeria, India, and China
Autorzy:: Omolola Oyedepo, Elizabeth
Tematy:: labor force
economic performance
demographic change
population dynamics
ARDL model; Pokaż więcej
Wydawca:: Uniwersytet Ekonomiczny w Katowicach
Powiązania:: https://bibliotekanauki.pl/articles/32443882.pdf Link otwiera się w nowym oknie
Opis:: Aim/purpose – This study investigated the nexus between labor force dynamics and economic performance in Nigeria, India, and China. Design/methodology/approach – The study used annual time series data spanning from 1991 to 2021 obtained from World Development Indicators (WDI). After the unit root stationarity test, the Autoregressive Distributed Lag Model (ARDL) was used for the analysis. Findings – Findings from the study support a positive short-run relationship between labor force participation and economic growth in all three countries. However, in China, population growth impacts the economy positively in the long run, while life expectancy at birth negatively impacts the economy in the short run. This is because China’s population is aging. In India, employment in the industrial and service sectors positively impacts the economy in the long run. In the short run, life expectancy at birth influences the economy negatively. Furthermore, in Nigeria, the industrial and service sector employment impact the economy negatively in the long run, though there are positive effects in the short run. Research implications – The Indian government needs policy reforms in the areas of education and health to take advantage of the potential of its youthful population. The Nigerian government requires implementing a wide range of education, investment, and employment-generating policies to foster tangible economic growth. These reforms could help both India and Nigeria take advantage of the potential for demographic change. The Chinese government, already having policy reforms in place, is geared towards improved fertility and population growth for economic growth in the near future. These policies, coupled with the study’s findings, could provide a more comprehensive understanding of the implications of demographic change on economic performance. Originality/value contribution – This analysis explored and compared the demographic potentials of two young countries (India and Nigeria) and an aging, wealthy economy (China) from the working class. Policy lessons for the attainment of demographic dividends are borrowed from China.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Divergent population dynamics: The case of the inner city of Riga
Dywergencja dynamiki populacji: przypadek centrum Rygi
Autorzy:: Balode, Sindija
Krišjāne, Zaiga
Tematy:: dynamika populacji
rozwój miast
reurbanizacja
population dynamics
urban development
reurbanisation; Pokaż więcej
Wydawca:: Uniwersytet im. Adama Mickiewicza w Poznaniu
Powiązania:: https://bibliotekanauki.pl/articles/55993572.pdf Link otwiera się w nowym oknie
Opis:: Population dynamics shape the spatial landscape of Europe. Although broadly studied, both suburban sprawl and inner-city reurbanisation have often been treated in isolation. Furthermore, these processes manifest distinctively across different local contexts. This research aimed to explore the population dynamics in the inner city of Riga from 2011 to 2021, contrasting them with the bordering municipalities of Riga, and to analyze how these dynamics align with the urban development model. Covering 58 neighborhoods and 7 bordering municipalities of Riga, the analysis revealed a shift in the trajectory of inner-city population dynamics during the latter half of the decade, which was finally characterized by growth. However, suburbanisation continued to outpace reurbanisation, indicating the coexistence of multiple urban development model stages.
Dynamika populacji wpływa na krajobraz przestrzenny Europy. Choć w literaturze podejmuje się badania w tym aspekcie zarówno obszarów podmiejskich, jak i śródmiejskich, to często traktowane są one oddzielnie. Co więcej, procesy te są odmienne w różnych kontekstach lokalnych. Celem opracowania było zbadanie dynamiki populacji w centrum Rygi w latach 2011–2021, porównanie z sąsiadującymi gminami Rygi, a także przeanalizowanie sposobu, w jaki dynamika ta odpowiada modelowi rozwoju obszarów miejskich. Analiza, obejmująca 58 dzielnic Rygi i 7 sąsiadujących gmin, wykazała zmianę trajektorii dynamiki populacji śródmiejskiej w drugiej połowie dekady, która ostatecznie charakteryzowała się wzrostem. Należy podkreślić, że urbanizacja w dalszym ciągu wyprzedzała reurbanizację, co wskazuje na współistnienie wielu etapów modelu rozwoju obszarów miejskich.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Population changes and characteristics of demographic processes in Tbilisi
Zmiany liczby ludności i charakter procesów demograficznych w Tbilisi
Autorzy:: Meladze, Giorgi
Loladze, Nika
Tematy:: płodność
migracje
prognoza
dynamika liczby ludności
fertility
migration
Tbilisi
prognosis
population dynamics; Pokaż więcej
Wydawca:: Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Powiązania:: https://bibliotekanauki.pl/articles/691729.pdf Link otwiera się w nowym oknie
Opis:: Na początku lat 90. XX wieku w Gruzji miało miejsce natychmiastowe zakończenie wieloletnich stosunków gospodarczych ze Związkiem Radzieckim. Dodatkowo konflikty zbrojne w Abchazji i Osetii Północnej doprowadziły do kryzysu społeczno-gospodarczego i politycznego w Gruzji. Wszystkie te wydarzenia miały ogromny wpływ na procesy demograficzne w Tbilisi. Niniejszy artykuł ma na celu ukazanie głównych czynników społeczno-ekonomicznych i kulturowych dotyczących zmian demograficznych i procesów demograficznych w postsowieckiej Tbilisi. Dodatkowo autorzy przedstawili prognozy zmian liczby ludności w latach 2015–2030.
At the beginning of the 1990s, as a result of the dissolution of the Soviet Union, an instant termination of economic relations that had existed for dozens of years took place in Georgia. Along with the armed conflicts in the regions of Tskhinvali and Abkhazia it has led to a full-fledged socio-economic and political crisis in Georgia. These unordinary events have had a great influence on the demographic processes at hand in Tbilisi. This article aims to establish the effects of the main socio-economic and cultural factors on population change and demographic processes in post-Soviet Tbilisi and offers prognosis on population change according to low, medium and high estimates for 2015–2030.
Dostawca treści:: Biblioteka Nauki

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