Population Dynamics of Cities in a Region: Conditions for a State of Simultaneous Growth

1979 ◽  
Vol 11 (6) ◽  
pp. 609-628 ◽  
Author(s):  
A Okabe
Keyword(s):  
Population Dynamics ◽  
Data Analysis ◽  
Nonlinear Dynamic ◽  
Total Population ◽  
Migration Model ◽  
Migration Flows ◽  
Empirical Implications ◽  
Over Time ◽  
Simultaneous Growth

This paper first proposes a nonlinear dynamic migration model that describes the population dynamics of cities in a region. Second, by use of this model, several theorems are proved about the conditions necessary for (1) a state of simultaneous growth (that is, when the population of every city in a region increases simultaneously), and (2) a state of proportional growth (that is, when every city's proportion of the total population remains the same over time). Third, based upon the data analysis of interprefectural migration flows in Japan in 1970, some empirical implications of these theorems are considered.

scholarly journals COVID-19 data analysis and modeling in Palestine

2020 ◽  
Author(s):  
Ines Abdeljaoued-Tej
Keyword(s):  
Population Dynamics ◽  
Data Analysis ◽  
Reproduction Number ◽  
Transmission Rate ◽  
Removal Rate ◽  
Reproductive Number ◽  
Critical Threshold ◽  
Actual Number ◽  
Over Time ◽  
The Basic Reproduction Number

AbstractWe estimate an actual number of infected cases in Palestine based on the 18-day effect from infection to death. We find that the number of cases in April 22 varies between 506 and 2 026 infected cases. We also focus on the reproductive number in Palestine based on population dynamics with two SEIR models. Dataset is from 5 March to 22 April 2020. With a transmission rate equal to 4.55 10−6, on May 22, the simulations predict 11 014 total infected cases in the optimistic scenario and 113 171 in the worst one. The crest of the pandemic is from 22 to 27 May 2020. The reproductive number ℛ0 is equal to 1.54 for a fixed fraction of 0.6 of symptomatic cases that are reported and for a removal rate of 7. Palestinian COVID-19 mortality number is equal to 6 per million. It is small compared to countries neighboring Palestine. The infected number is equal to 88.4 per million, which is less than most of its neighbors. The basic reproduction number is still greater than 1. Changes to the transmission rate (over time) would be advisable, to fall ℛ0 below the critical threshold.

Pengaruh Pengembangan Karir dan Penempatan Kerja Terhadap Prestasi Kerja Karyawan pada PDAM Tirtanadi Provinsi Sumatera Utara

MBIA ◽  
2019 ◽  
Vol 17 (3) ◽  
pp. 17-24
Author(s):  
Cut Ermiati ◽  
Dita Amanah ◽  
Dedy Ansari Harahap ◽  
Fitriani Tanjung
Keyword(s):  
Data Analysis ◽  
Career Development ◽  
Linear Regression ◽  
Work Performance ◽  
Total Population ◽  
Employee Performance ◽  
Work Placement ◽  
Analysis Technique ◽  
Calculation Results ◽  
North Sumatra

This study aims to determine the effect of career development and work placement on employee work performance at PDAM Tirtanadi, North Sumatra Province. The population in this study were all employees per division, amounting to 182 employees. From the total population can be determined the number of samples in this study amounted to 65 people. The data analysis technique used is the t-test, f-test, multiple linear regression and determinant coefficient test using SPSS 22. From the calculation results using SPSS shows that there is an influence of career development on employee work performance, there is the influence of work placement on employee performance and there is the influence of career development and work placement on employee performance.

scholarly journals Analysis of 220 Years of Floodplain Population Dynamics in the US at Different Spatial Scales

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 141
Author(s):  
Firoza Akhter ◽  
Maurizio Mazzoleni ◽  
Luigia Brandimarte
Keyword(s):  
Population Dynamics ◽  
Large Scale ◽  
Spatial Scales ◽  
National Level ◽  
State Level ◽  
Economic Activities ◽  
Protection Measures ◽  
Management Planning ◽  
The Us ◽  
Over Time

In this study, we explore the long-term trends of floodplain population dynamics at different spatial scales in the contiguous United States (U.S.). We exploit different types of datasets from 1790–2010—i.e., decadal spatial distribution for the population density in the US, global floodplains dataset, large-scale data of flood occurrence and damage, and structural and nonstructural flood protection measures for the US. At the national level, we found that the population initially settled down within the floodplains and then spread across its territory over time. At the state level, we observed that flood damages and national protection measures might have contributed to a learning effect, which in turn, shaped the floodplain population dynamics over time. Finally, at the county level, other socio-economic factors such as local flood insurances, economic activities, and socio-political context may predominantly influence the dynamics. Our study shows that different influencing factors affect floodplain population dynamics at different spatial scales. These facts are crucial for a reliable development and implementation of flood risk management planning.

QUALITATIVE PROPERTIES OF A POPULATION DYNAMICS SYSTEM DESCRIBING PREGNANCY

2005 ◽  
Vol 15 (04) ◽  
pp. 507-554 ◽  
Author(s):  
G. FRAGNELLI ◽  
P. MARTINEZ ◽  
J. VANCOSTENOBLE
Keyword(s):  
Population Dynamics ◽  
Asymptotic Behavior ◽  
Linear Model ◽  
Nonlinear Model ◽  
Total Population ◽  
Type A ◽  
Qualitative Properties

We study a model of population dynamics describing pregnancy: our model is composed by an equation describing the evolution of the total population, and an equation describing the evolution of pregnant individuals. These equations are of course coupled: one coupling expresses that the total population varies with the number of born people, and another coupling says that the number of fecundated individuals depends on the total population. We study three models of that type: a linear model without diffusion, a nonlinear model without diffusion and a linear model with diffusion. For these three models, we study precisely the qualitative properties and the asymptotic behavior of the solutions.

scholarly journals The influence of microhabitat on the population dynamics of four herbaceous species in a semiarid area of northeastern Brazil

2016 ◽  
Vol 76 (1) ◽  
pp. 45-54 ◽  
Author(s):  
K. A. Silva ◽  
J. M. F. F. Santos ◽  
J. R. Andrade ◽  
E. N. Lima ◽  
U. P. Albuquerque ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Population Size ◽  
Mortality Rates ◽  
Dry Forest ◽  
Northeastern Brazil ◽  
Annual Rainfall ◽  
Herbaceous Species ◽  
Forest Fragment ◽  
Experimental Station ◽  
Over Time

Abstract Variation in annual rainfall is considered the most important factor influencing population dynamics in dry environments. However, different factors may control population dynamics in different microhabitats. This study recognizes that microhabitat variation may attenuate the influence of climatic seasonality on the population dynamics of herbaceous species in dry forest (Caatinga) areas of Brazil. We evaluated the influence of three microhabitats (flat, rocky and riparian) on the population dynamics of four herbaceous species (Delilia biflora, Commelina obliqua, Phaseolus peduncularis and Euphorbia heterophylla) in a Caatinga (dry forest) fragment at the Experimental Station of the Agronomic Research Institute of Pernambuco in Brazil, over a period of three years. D. biflora, C. obliqua and P. peduncularis were found in all microhabitats, but they were present at low densities in the riparian microhabitat. There was no record of E. heterophylla in the riparian microhabitat. Population size, mortality rates and natality rates varied over time in each microhabitat. This study indicates that different establishment conditions influenced the population size and occurrence of the four species, and it confirms that microhabitat can attenuate the effect of drought stress on mortality during the dry season, but the strength of this attenuator role may vary with time and species.

scholarly journals The dynamics of questing ticks collected for 164 consecutive months off the vegetation of two landscape zones in the Kruger National Park (1988–2002). Part II. Rhipicephalus appendiculatus and Rhipicephalus zambeziensis

2011 ◽  
Vol 78 (1) ◽  
Author(s):  
Arthur M. Spickett ◽  
Gordon J. Gallivan ◽  
Ivan G. Horak
Keyword(s):  
Population Dynamics ◽  
Relative Humidity ◽  
National Park ◽  
Rhipicephalus Appendiculatus ◽  
Kruger National Park ◽  
Large Herbivore ◽  
Questing Ticks ◽  
Over Time

The study aimed to assess the long-term population dynamics of questing Rhipicephalus appendiculatus and Rhipicephalus zambeziensis in two landscape zones of the Kruger National Park (KNP). Ticks were collected by dragging the vegetation monthly in three habitats (grassland, woodland and gully) at two sites in the KNP (Nhlowa Road and Skukuza) from August 1988 to March 2002. Larvae were the most commonly collected stage of both species. More R. appendiculatus were collected at Nhlowa Road than at Skukuza, with larvae being most abundant from May to August, while nymphs were most abundant from August to December. Larvae were most commonly collected in the gullies from 1991 to 1994, but in the grassland and woodland habitats from 1998 onwards. Nymphs were most commonly collected in the grassland and woodland. More R. zambeziensis were collected at Skukuza than at Nhlowa Road, with larvae being most abundant from May to September, while nymphs were most abundant from August to November. Larvae and nymphs were most commonly collected in the woodland and gullies and least commonly in the grassland (p < 0.01). The lowest numbers of R. appendiculatus were collected in the mid-1990s after the 1991/1992 drought. Rhipicephalus zambeziensis numbers declined after 1991 and even further after 1998, dropping to their lowest levels during 2002. The changes in numbers of these two species reflected changes in rainfall and the populations of several of their large herbivore hosts, as well as differences in the relative humidity between the two sites over time.

The Impact of the Movement of Labour: Results from a Model of Bilateral Migration Flows

2011 ◽  
Vol 11 (4) ◽  
pp. 1850240 ◽  
Author(s):  
Terrie L. Walmsley ◽  
Alan Winters ◽  
Amer Ahmed
Keyword(s):  
Developing Economies ◽  
Migration Model ◽  
Global Migration ◽  
Developed Economies ◽  
Migration Data ◽  
Economics Literature ◽  
Unskilled Labour ◽  
Migration Flows ◽  
The Impact

The economics literature increasingly recognizes the importance of migration. In this paper, a bilateral global migration model is developed to investigate the impact of lifting restrictions on the movement of labour. Quotas on skilled and unskilled labour in the developed economies are increased by 3% of their labour forces, with the additional labour supplied by developing economies. This paper improves upon the previous work of Walmsley and Winters (2005). A critical weakness of the previous work was that it was unable to capture the impacts of specific bilateral migration flows or liberalizations between countries. This paper uses a bilateral global migration model that exploits migration data obtained from Parsons, Skeldon, Winters, and Walmsley (2007) that allow the model to account for bilateral migration flows. The results confirm that restrictions on migration impose significant costs on nearly all countries, with the modest liberalization increasing global GDP by US$ 288 billion. All of the developed (labour importing) economies gain in terms of real incomes. While results differ across the developing (labour exporting) economies, most gain as a result of the higher remittances sent home.

scholarly journals THE USE OF VIDEO TO IMPROVE STUDENTS' PRONUNCIATION COMPETENCE AT SMP NEGERI 8 PULAU MOROTAI

2021 ◽  
Author(s):  
balqis husain ◽  
Fincun Makatika ◽  
Megawati Basri
Keyword(s):  
Data Analysis ◽  
Experimental Method ◽  
Random Sampling ◽  
Total Population ◽  
Simple Random Sampling ◽  
Quantitative Approach

This research aims to determine whether or not VOA video can improve students' pronunciation at SMPN 8 Pulau Morotai. This research was conducted at eight grade students of SMP N 8 Pulau Morotai. Thedesign of this research used a quantitative approach, particularly the true-experimental method. Thesampling technique was simple random sampling through a lottery, the sample in this research was 21students, and the total population was 24 students. The data analysis used Wilcoxon Signed Ranks Test.The finding showed that Asymp. Sig (2-tailed) was 0.008; it can be said that Hypothesis null was rejected(p&gt;0.05), and Ha was accepted.

scholarly journals Population Dynamics and Tree Damage of the Invasive Chestnut Gall Wasp, Dryocosmus kuriphilus, in Its Southernmost European Distributional Range

Insects ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 900
Author(s):  
Javier Quinto ◽  
María Eva Wong ◽  
Juan Ramón Boyero ◽  
José Miguel Vela ◽  
Martin Aguirrebengoa
Keyword(s):  
Population Dynamics ◽  
Control Mechanisms ◽  
Gall Wasp ◽  
Local Conditions ◽  
Tree Damage ◽  
Dryocosmus Kuriphilus ◽  
Distributional Range ◽  
The Status ◽  
Spatio Temporal ◽  
Over Time

The invasive chestnut gall wasp (CGW), Dryocosmus kuriphilus, the worst pest of chestnut cultivation, has spread worryingly throughout Europe in less than 20 years. Despite the great concern around this pest, little is known about the status in its southernmost distribution in continental Europe. We assessed spatio-temporal patterns in the population dynamics, phenology and tree damage caused by CGW in southern Spain. Likewise, the relationship between these variables and thermal trends was evaluated. We found strong variation in the population dynamics and flight phenology among localities and over time, which were highly influenced by changes in thermal regimes. Specifically, warmer localities and vegetative periods promoted higher population densities, a partial increase in the survival of immature stages, and advanced flight activity. Moreover, tree damage evolved differently over time in each locality, which suggests that local conditions may determine differences in damage evolution. Our findings evidence that great spatio-temporal variability in the CGW populations takes place across invaded areas in its southernmost European distributional range. Although control mechanisms have been introduced, implementation of further control and management measures are critical to cope with this main threat for the chestnut industry and to prevent its spread to nearing chestnut-producing areas.

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