scholarly journals Dynamic Modes of Limited Structured Population under Age Specific Harvest

2017 ◽  
Vol 12 (2) ◽  
pp. 327-342 ◽  
Author(s):  
Г.П. Неверова ◽  
G.P. Neverova
Keyword(s):  
Population Size ◽  
Age Groups ◽  
Stability Loss ◽  
Maximum Sustainable Yield ◽  
Harvest Rate ◽  
Attraction Basin ◽  
Current Population ◽  
Reproduction Process ◽  
Reproduction Season ◽  
The Stability

The paper investigates influence of age specific harvest on the dynamics of populations with density dependent regulation of birth rate. We consider the population which by the end of each reproduction season, consists of two age groups: juveniles (immature individuals) and adults (participants of the reproduction process). A harvest rate growth of any age class is shown to give, as a rule, the dynamics stabilization. However, the system with harvesting demonstrates multimodality phenomenon as well as the population model without exploitation. The phenomenon means different dynamic modes are observed with the same values of the population parameters. As a result, some difficulties occur in predicting population dynamics, because harvest can lead to significant changes of population size due to shifting current population size from one attraction basin to another. To neutralize the oscillations emerged is necessary to change the current population size so that it falls into the attraction basin of the fixed point. The stability loss way of model with juvenile harvesting does not depend on the harvest rate value and is completely determined by the intensity of competitive relationships between the age classes. In the case of adult exploitation, a higher harvest rate can result in growing stationary population size. The changing the time of adult harvesting can lead to both the dynamics population stabilization and the occurrence of fluctuations. Exploitation before the reproduction season allows to have more yield than after reproduction season because mature age group size is higher. Conditions when the age specific harvest gives the maximum sustainable yield are considered.

scholarly journals The effect of change in population size on DNA polymorphism.

Genetics ◽  
1989 ◽  
Vol 123 (3) ◽  
pp. 597-601 ◽  
Author(s):  
F Tajima
Keyword(s):  
Population Size ◽  
Dna Sequences ◽  
Dna Polymorphism ◽  
Population Bottleneck ◽  
Expected Number ◽  
Original Population ◽  
Current Population ◽  
Segregating Sites

Abstract The expected number of segregating sites and the expectation of the average number of nucleotide differences among DNA sequences randomly sampled from a population, which is not in equilibrium, have been developed. The results obtained indicate that, in the case where the population size has changed drastically, the number of segregating sites is influenced by the size of the current population more strongly than is the average number of nucleotide differences, while the average number of nucleotide differences is affected by the size of the original population more severely than is the number of segregating sites. The results also indicate that the average number of nucleotide differences is affected by a population bottleneck more strongly than is the number of segregating sites.

Production, Mortality, And Sustainable Yield Of Northwest Atlantic Harp Seals (Pagophilus groenlandicus)

1978 ◽  
Vol 35 (9) ◽  
pp. 1249-1261 ◽  
Author(s):  
G. H. Winters
Keyword(s):  
Population Size ◽  
Total Population ◽  
Historical Data ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Natural Mortality ◽  
Northwest Atlantic ◽  
The Past ◽  
Relative Contribution ◽  
Pagophilus Groenlandicus

From recent and historical data the natural mortality rate of adult harp seals (Pagophilus groenlandicus) is estimated to be 0.10 which is within the range of previous estimates (0.08–0.11). New estimates of bedlamer and 0-group natural mortality rates were not significantly different from those of adult seals. Pup production estimates from survival indices agreed well with those from sequential population analyses and indicated a decline from about 350 000 animals in the early 1950s to about 310 000 animals in the early 1970s. Over the same period the 1+ population size declined from 2.5 to 1.1 million animals but has been increasing at the rate of 3%/yr since the introduction of quotas in 1972. The relative contribution of the "Front" production to total ("Front" plus Gulf) production during the past decade has fluctuated from 49 to 87%, the average of 64% being very similar to the 61% obtained previously. These fluctuations suggest some interchange between "Front" and Gulf adults and it is concluded that homing in the breeding areas is a facultative rather than obligatory aspect of seal behavior. Thus the heavier exploitation of the "Front" production is probably sufficiently diffused into the total population to avoid serious effects on "Front" production. The maximum sustainable yield of Northwest Atlantic seals harvested according to recent patterns is estimated to be 290 000 animals (80% pups) from a 1+ population size of 1.8 million animals producing 460 000 pups annually. The sustainable yield at present levels of pup production (335 000 animals) is calculated to be 220 000 animals which is substantially above the present TAC of 180 000 animals and coincides with present harvesting strategies designed to enable the seal hunt to increase slowly towards the MSY level. Key words: mortality, production, sustainable yield, population dynamics, marine mammal

Study on the bearing resistance of axially compressed L-shaped stainless steel core plate wall based on the stability loss

2021 ◽  
Vol 249 ◽  
pp. 113264
Author(s):  
Xing-Ping Shu ◽  
Huai-Bing Wang ◽  
Yi Li ◽  
Zhi-Shen Yuan ◽  
Ke Li
Keyword(s):  
Stainless Steel ◽  
Stability Loss ◽  
Steel Core ◽  
The Stability

DEMOGRAPHIC STABILITY OF ENTERPRISES: INDUSTRY SECTION

2021 ◽  
Author(s):  
Алёна Амирановна Арошидзе
Keyword(s):  
Economic Development ◽  
Age Groups ◽  
Demographic Analysis ◽  
Socio Economic Development ◽  
The Stability ◽  
Key Indicators ◽  
Industry Section

Демографический анализ предприятий служит одним из ключевых индикаторов социально-экономического развития страны. Кроме того, он позволяет в некоторой степени оценить результативность политики по стимулированию предпринимательской деятельности. В этой связи данная статья посвящена оценке жизненности предприятий по возрастным группам и стабильности отраслевых позиций по данному коэффициенту. Demographic analysis of enterprises is one of the key indicators of the country's socio-economic development. In addition, it allows to assess to some extent the effectiveness of policies to stimulate entrepreneurship. In this regard, this article is devoted to assessing the viability of enterprises by age groups and the stability of industry positions according to this coefficient.

scholarly journals Statistical Estimation of Modern Trends and Prospects of the Size and Structure Population of Ukraine

2017 ◽  
pp. 65-72
Author(s):  
Z. О. Palian ◽  
I. H. Bondarenko
Keyword(s):  
Population Size ◽  
Age Structure ◽  
Structural Changes ◽  
Age Groups ◽  
Natural Increase ◽  
Reproductive Age ◽  
Structural Factors ◽  
Forecast Horizon ◽  
The Crimea ◽  
Size And Structure

A balanced change in demographic processes should be considered as a prerequisite and, at the same time, as a result of the stable development of the state. Reproduction intensity depends not only on the character of demographic behavior, but also on the presence of contingents of the population, providing or potentially able to provide for its replacement. The dynamics of Ukrainian population, the transformation of its gender-age structure during the period of independence, taking into account the intensive and structural factors of natural increase and migration, is considered. During 2002-2015, the regime of survival and fertility improved in Ukraine, due to which the depopulation slowed down somewhat. But even these positive changes do not compensate for the loss of population size as a result of systematic aging, reducing the proportion of reproductive contingent and its aging. Significant demographic losses, direct and indirect, were caused by a hybrid war from Russia. Alienation of the territory of the Crimea and parts of Donbas is not only a minus 2.5 million citizens of Ukraine. This is a change in the structure of the population - a decrease in the proportion of older age groups that increase the demographic load and worsen the characteristics of survival and fertility of the maternal generation. In this work are presented the results of the short-term simulation of population size and structure taking into account modern trends of replacements components and existing administrative-territorial changes. Two scenarios of the forecast for 2018 have been developed, and the base year it was taken in 2013, when the Crimea was part of Ukraine. The first, realistic scenario was based on the preservation of the current situation - Ukraine without the annexed Crimea and the occupied part of the Donbas. The second scenario imitates the return to Ukraine of all the lost territories. Simulation showed that the population of Ukraine will be reduced by both scenarios, but to 41.9 million people under the scenario without the occupied and annexed territories and to 44.7 million people in the second scenario. The finish of war will due to slow down the death rate to 14.9%0. The age structure of the population does not differ significantly in two scenarios, because the forecast horizon is very short (4 years). The share of generation of parents and women of reproductive age in both variants of the forecast decreases. However, in the case of returning Crimea, it will be even lower (47.4% vs. 47.5% in the first scenario). The reason for this is the emigration of young and middle-aged people to the mainland of Ukraine and to the Russian Federation, which provided some preferences to the settlers from Ukraine. Expected structural changes combined with the modern life and fertility regime will worsen natural population growth rates in both scenarios. In further research is planned to build trend models of births and deaths that will allow the artificially restore the interrupted time series due to administrative-territorial incomparability of data on demographic events

scholarly journals The role of the antioxidant: Selenopyran in the stability of the antioxidant system to toxic effect of cadmium chloride

2007 ◽  
Vol 23 (5-6-1) ◽  
pp. 181-191
Author(s):  
U. Kravchenko ◽  
G. Borjaev ◽  
M. Nevitov ◽  
A. Ostapchuk ◽  
E. Kistanova
Keyword(s):  
Oxidative Stress ◽  
Antioxidant System ◽  
Antioxidant Defense ◽  
Age Groups ◽  
Selenium Concentration ◽  
Antioxidant Defense System ◽  
The Stability ◽  
Gpx Activity ◽  
Preventive Role

The purpose of the present work was, under conditions of the model experiment on rats, to tap the information about the features of shortterm acclimatization of the antioxidant system in various organs to toxicity of cadmium at stages of an ontogenesis and about the preventive role of the antioxidant selenopyran in this process. The obtained results showed the ontogenetic differences in the adaptive reactivity of the enzymatic antioxidant defense system in the most important organs and tissues of rats under conditions of oxidative stress induced by cadmium. The ontogenetic differences of Se redistribution in a body under influence of cadmium administration were found. The discovered decrease of Se concentration in the liver of young animals and the increase of its concentration in the liver of old animals correlated positively with the changes of GPx activity. Preventive administration of selenopyran (9- phenyl-simmetrical octa-hydroselenoxanthene) to old animals reduced the oxidative stress intensity. Animals of all age groups showed higher selenium concentration in the tissues and the increase in the selenium-dependent GPx activity.

scholarly journals ALGORITHM AND SOFTWARE FOR CALCULATING THE STABILITY OF THE FORM OF EQUILIBRIUM OF DISCRETE SYSTEMS

2019 ◽  
Vol 13 (3) ◽  
pp. 44-49
Author(s):  
A.A. SHKURUPIY ◽  
A.N. PASCHENKO ◽  
P.B. MYTROFANOV
Keyword(s):  
Discrete Systems ◽  
Stability Loss ◽  
Transcendental Equation ◽  
Loss Of Stability ◽  
Displacement Method ◽  
Software Complex ◽  
Complex Functions ◽  
Transcendental Functions ◽  
The Stability ◽  
Theoretical Mechanics

The paper presents an algorithm for calculating the stability of the form of equilibrium of the first kind of compressed discrete systems by the method of displacements in combination with themethods of iterations and bisection. The use of the displacement method in combination with the iteration and bisection methods makes it possible to effectively determine the minimum critical stress or strain at the first bifurcation and their corresponding form of loss of stability, both for statically determined and statically undetectable systems. This approach, using matrixforms, makes it possible to significantly simplify the calculations of the analytical condition for the loss of stability of compressed discrete systems (the stability loss equation), which has high orders, as well as to construct the form of loss of stability corresponding to a critical load, that is, to solve the problem of loss of stability of equilibrium. The calculation of the compressed discrete system on the stability of the form of equilibrium actually reduces to the solution of the difficultly described nonlinear transcendental equation, which is the equation of loss of stability. The difficulty lies in the absence of an analytical solution of such an equation due to the presence of complex functions of Zhukovsky, which have transcendental functions in their structure. Such solution can be performed only with the use of numerical methods. This algorithm for calculating the loss of equilibrium of the first kind of compressed discrete systems by displacement in combination with the methods of iteration and bisection is implemented in the software complex "Persist" for a PC in Windows OS. The program was approbated and implemented in theeducational process at the Department of Structural and Theoretical Mechanics of the Poltava National Technical Yuri Kondratyuk University during the training of specialists in engineering specialties.

scholarly journals Influence of seasonal changes on the karyotype stability of Ukrainian Black and White dairy cows

2020 ◽  
Vol 22 (93) ◽  
pp. 29-34
Author(s):  
N. Y. Temekh ◽  
L. F. Starodub
Keyword(s):  
Seasonal Changes ◽  
Age Groups ◽  
Summer Season ◽  
Black And White ◽  
Structural Disorders ◽  
Different Seasons ◽  
The Stability ◽  
The Impact ◽  
Dairy Breed ◽  
Karyotype Stability

Of the total dairy cattle, 49 % belong to the Ukrainian black-and-white dairy breed. Animals are demanding to the conditions of detention, so the aim of the study was to study the impact of seasonal changes in the environment on the stability of the karyotype of cows of three age groups (first-born, adult and cows 8–10 years). The variability of the karyotype of the studied animals in different seasons of the year was manifested in the form of quantitative and structural disorders of chromosomes. Of the total dairy cattle, 49 % belong to the Ukrainian black-and-white dairy breed. Animals are demanding to the conditions of detention, so the aim of the study was to study the impact of seasonal changes in the environment on the stability of the karyotype of cows of three age groups (first-born, adult and cows 8–10 years). The variability of the karyotype of the studied animals in different seasons of the year was manifested in the form of quantitative and structural disorders of chromosomes. In primiparous women, the most pronounced genomic variability (aneuploidy) was observed in summer and winter and was 16.4 % and 8.8 %. In summer, this variability was more than twice the limit of spontaneous chromosomal variability. The highest percentage of structural chromosome abnormalities (chromosomal breaks) in cows of three age groups was observed in winter and was 2.5 %, 2.8 %, 3.0 %, respectively, and did not exceed the limit of spontaneous mutagenesis characteristic of cattle. An increased proportion of lymphocytes with a micronucleus in first-borns and cows aged 8–10 years (5.6 ‰, 6.4 ‰, respectively) was observed in the summer. The increased proportion of dinuclear lymphocytes appeared in the first-born in the summer season and amounted to 7.6 ‰ (at P > 0.99), and in cows 8–10 years, this variability in the summer season was 6.2 ‰, in winter – 6.7 ‰ with a statistically significant difference (P > 0.95) between the spontaneous level of cytogenetic variability. The association between karyotype stability of the studied animals and seasonal environmental factors was determined using a correlation coefficient (r). A significant positive correlation was found between aneuploidy and air temperature in primiparous and cows aged 8–10 years, relative humidity, precipitation and wind strength and chromosomal gaps in primiparous and adult cows, atmospheric pressure, relative humidity and asynchronous divergence. in adult cows and cows aged 8–10 years. A positive reliable associative dependence of the appearance of micronucleus lymphocytes and dinuclear lymphocytes on the amount of precipitation and wind strength in this area in primiparous and adult cows was established.

scholarly journals ANÁLISE DA INTEGRIDADE E DA INSTABILIDADE DINÂMICA DE UM SISTEMA MECÂNICO SUJEITO A BIFURAÇÃO DO TIPO BUTTERFLY

2021 ◽  
Vol 12 (3) ◽  
pp. 14-22
Author(s):  
Michael Dowglas de Gois Silva ◽  
Fábio Roberto Chavarette ◽  
Milton Batista Ferreira Junior ◽  
Rodrigo Francisco Borges Lourenco
Keyword(s):  
Static Load ◽  
Structural Systems ◽  
Spring Stiffness ◽  
Bifurcation Diagrams ◽  
Model Uncertainties ◽  
Geometric Imperfections ◽  
Attraction Basin ◽  
Linear Buckling ◽  
Lower Load ◽  
The Stability

Slender structural systems susceptible to unstable buckling generally losestability at lower load levels than the linear buckling load of the perfect structure. This is mainly due to the geometric imperfections present in real structures. The objective of this work is to determine the integrity measures, together with the stability of the post-critical solutions of a mechanical system subject to unstable symmetrical buckling, Burtterfly-type bifurcation, using a discrete degree of freedom model. Uncertainties in the order of 10% will be considered in its deterministic parameters, to obtain lower and reliable limits for the project. The proposed uncertainty in the spring stiffness parameters does not change the type of bifurcation and the value of the critical load, only the value of the minimum post-critical of the bifurcation diagrams. The results showed the erosion of the attraction basin and the decrease of the factors of integrity, local and global, for the trivial solutions with the increase of the static load, for the investigated bifurcation.

Reliability Estimates and Age and Gender Comparisons of Expectations of Success in Sex-Typed Activities

1985 ◽  
Vol 7 (4) ◽  
pp. 379-388 ◽  
Author(s):  
Charlotte Sanguinetti ◽  
Amelia M. Lee ◽  
Jack Nelson
Keyword(s):  
Skill Acquisition ◽  
Motor Skill ◽  
Age Groups ◽  
Motor Tasks ◽  
Sex Typing ◽  
Age And Gender ◽  
Motor Skill Acquisition ◽  
Reliability Estimates ◽  
And Gender ◽  
The Stability

The purposes of this study were to determine the stability of estimations of success in masculine, feminine, and gender-neutral motor tasks with subjects of three age groups, and to compare expectancies for success of boys and girls at each of the ages. A total of 90 subjects took part in the study, including 15 males and 15 females randomly selected from the three age groups (grades 1 & 2; grades 6 & 7; and adults). Three activities (football, ballet, and swimming) had been sex-typed in a previous study as masculine, feminine, and neutral, respectively. Subjects were asked to indicate how they would expect to perform on three occasions in all three tasks. Results indicated that all age groups can provide reliable expectations for their success in motor skill acquisition, although the younger children's estimates are slightly less reliable, especially on the first trial. Sex-typing of activities was found to definitely affect the performance estimations in all three age groups. Males' expectancies were higher on the male task and females' expectancies were higher on the female task. The younger children's overall estimates of success were higher than those of the older groups.

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