In this paper, we analyse demographic data obtained from the population census of Japan carried out in 2005 and 2010, which are provided with a high spatial resolution . Dependence of the population growth rate in a cell on the population density at distance d, ρ¯(d), calculated for the population change between2000 and 2005. Second, rapid population growth encourages international migration. Humans whose migratory behaviour is to be modelled microscopically, statistically or otherwise, may pay less attention to such a unit than a model assumes when they make a decision to move home. Different geographical, demographic and econo-societal factors seem to contribute to migratory decisions made by individual inhabitants. (c) Outflow for the GM. To reach its biotic potential, all females would have to become pregnant every nine months or so during their reproductive years. (e) (t1,t2)=(2005,2010), dag=25 km. (b) s-aggregate GM. We then show that the empirical observation is better accounted for by extensions of the gravity model such that individuals are assumed to perceive the attractiveness, approximated by the population density, of the source or destination cell of migration as the spatial average over a circle of radius ≈1 km. In 6-week old mice, osteoblast density drops 77% after 14 days in a microgravity environment as opposed to a 17% drop in 6-month old mice (Basso et al. Lastly, we investigated an extension of the GM with the aggregation of cells around both the source and destination cells, called the sd-aggregate GM (appendix E). Figure 10. The results for the GM were inaccurate for all parameter combinations that we considered (figure 11a). As a result, the net flow for the sd-aggregate GM (figure 22a) was similar to that for the d-aggregate GM (figure 9d) and the s-aggregate GM (figure 9g). Singer David Bowie wrote “Space Oddity” describing the experiences of the astronaut Major Tom: “I am floating in a most peculiar way”. The biggest problem about low gravity and development is reproduction. We thus divided the range of the latitude into 45 windows, i.e. (f) s-aggregate GM, dag=25 km.Download figureOpen in new tabDownload powerPoint. Dependence of the population growth rate in a cell on the population density at distance d, ρk(d), calculated from the empirical data. In spite of population control policies, the human population continues to grow. [24, 24,5), [24.5, 25),…, [45.5,46]. To calculate ρ¯(d), we used all regions. 3.11 Effects of artificial gravity. Other developed countries, such as Italy, have zero population growth. We also confirmed that the discrepancy measure for the sd-aggregate GM increased as dag increased (figures 20 and 21), similar to the results for the d-aggregate and s-aggregate GMs (figures 6 and 7). The relative contribution of migration to demographic dynamics, denoted by RC in the table, is defined by (inflow + outflow)/(the number of births + the number of deaths + inflow + outflow). The two lines almost overlap with each other. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. Figure 5. (e) (t1,t2)=(2005,2010), dag=25 km. We set α=0.4, β=0.4 and γ=1.0.Download figureOpen in new tabDownload powerPoint. However these effects have only be observed in micro gravity or no gravity. The discrepancy of d-aggregate GM and s-aggregate GM from the empirical data for the population change between 2000 and 2005. Figure 20. Studies show that weightlessness has a number of negative health effects. After more than 50 years of human spaceflight, NASA is an expert in what happens to the human body when it’s in zero gravity. In the past, diseases such as the bubonic plaque of the fourteenth century killed between 30 and 60 percent of Europe’s population and reduced the overall world population by as many as 100 million people. The discrepancy of the GM, d-aggregate GM and s-aggregate GM from the empirical data in terms of the discrepancy measure given by equation (2.8). This result suggests that cells surrounded by cells with a large (small) population density within ≈20 km are more … The survivor function of the number of inhabitants in a cell. The spatial correlation in the number of inhabitants in the cell. http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. (b) (t1,t2)=(2000,2005), dag=1 km. Other factors in human population growth are migration and public health. Public health, sanitation, and the use of antibiotics and vaccines have decreased the ability of infectious disease to limit human population growth. The model has attained reasonably accurate description of human migration in some cases [8,16,17], as well as other phenomena such as international trades [18,19] and the volume of phone calls between cities [20,21]. Note that there were sea regions without any inhabitant. The first extension, which we refer to as the GM with the spatially aggregated population density at the destination (d-aggregate GM), is given by, The second extension of the GM aggregates the population density around the source cell. We set α=0.4, β=0.4, γ=1 and dag=0.65 km.Download figureOpen in new tabDownload powerPointFigure 19. When we speak of mass, we’re talking about the amount of matter in a substance. Age structure allows better prediction of population growth, plus the ability to associate this growth with the level of economic development in the region. Portal Site of Official Statistics of Japan. This result reflects the observation that highly populated cells tend to grow and vice versa [35–37] (but see ). (b) (t1,t2)=(2000,2005). Figure 8. Enter your email address below and we will send you your username, If the address matches an existing account you will receive an email with instructions to retrieve your username, Department of Engineering Mathematics, University of Bristol, Merchant Venturers Building, Woodland Road, Clifton, Bristol BS8 1UB, UK, Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Aramaki aza Aoba 6-3, Aoba-ku, Sendai 980-8578, Japan. [122.4, 123), [123, 123.5),…, [153.5, 154]. We used data from the censuses conducted in 2005 and 2010 because data with such a high spatial resolution over the entirety of Japan were only available for these years. In the main text, we refer to the two time points 2005 and 2010 as t1 and t2, respectively. The performance of the d-aggregate GM was better than that of the s-aggregate GM in terms of the robustness against variation in the parameter values. population growth rate), inflow and outflow of populations as a function of x and x′ using the three GMs. We set α=0.4, β=0.4, γ=1 and dag=0.65 km. Figure 15. At this late date nothing can prevent a substantial increase in the world death rate.” While many critics view this statement as an exaggeration, the laws of exponential population growth are still in effect, and unchecked human population growth cannot continue indefinitely. See, Effects of the distant population density on spatial patterns of demographic dynamics, The number of births, deaths, incoming inhabitants and outgoing inhabitants in the 47 prefectures in Japan between 2005 and 2009. The number of inhabitants in cell i (1≤i≤K) at time t is denoted by ni(t). The spatial correlation in the number of inhabitants in the cell. In the standard gravity model (GM), the migration flow from source cell i to destination cell j (≠i), Tij, is given by, In addition to the GM, we investigated two extensions of the GM in which the migration flow depends on the numbers of inhabitants in a neighbourhood of cell i or j. In fact, individuals at a certain life stage are more likely to migrate in general [4,5]. In the main text, we used the data on the population census in Japan in 2005 and 2010. Mass is independent of gravity, unlike weight, which is the force exerted by mass due to the acceleration of gravity (F = ma). niα−1njβ/dijγ. In other words, the effects of the population density within 1 km is the most positively correlated with the growth rate of a cell. 2004). We tested an intermittent short-arm centrifuge of 1.4 G with 60-W ergometric exercise with a step-up increase of 0.2 G and 15 W, respectively, for 30 min every day for 21 days during −6° head-down bedrest . Additional information about the geographical property of cells such as the water area within the cell and the land use may improve the present analysis. Bulk density reflects the soil’s ability to function for structural support, water and nutrient and microbial life movement, and soil aeration. Here, we set t1=2000 and t2=2005 and ran the same analysis pipeline with that in the main text to examine the robustness of our results. (a) (t1,t2)=(2005,2010). Ocean acidification (OA) threatens coral reef futures by reducing the concentration of carbonate ions that corals need to construct their skeletons. According to the World Health Organization, global death from infectious disease declined from 16.4 million in 1993 to 14.7 million in 1992. The thick lines represent ρ¯(d), which is the average of ρk(d) over all the regions. The net flow, inflow and outflow for the GM, d-aggregate GM and s-aggregate GM in the one-dimensional model with 21 cells. The survival function of the number of inhabitants in a cell at t1 and t2 is shown in figure 2. (d) s-aggregate GM, dag=5 km. (f) Outflow for the d-aggregate GM. (b) (t1,t2)=(2000,2005). (b) (t1,t2)=(2000,2005). (b) Inflow for the GM. Figure 22. Blood pressure equalizes and becomes about 100 mmHg throughout the body. The depletion of the ozone layer, erosion due to acid rain, and damage from global climate change are caused by human activities. This chapter explores gravity, its impact on life when gravity changes, necessity of gravity for life, and the role of gravity in the evolution of life on the Earth. A number of models have been proposed to describe and predict spatio-temporal patterns of human migration [7–13]. Thus, we enter the future with considerable uncertainty about our ability to curb human population growth and protect our environment. The discrepancy of the GM, d-aggregate GM and s-aggregate GM from the empirical data, calculated for the population change between 2000 and 2005. In the main text, we aggregated the cells around either the source or destination cell but not both. Growth hormone at high doses may decrease body fat in these patients, but the effects of growth hormone at more physiologic doses on bone density and body composition have not been convincingly shown. A soils bulk density plays a huge role in determining the effectiveness of the soil and the future productivity of a farming operation. Humans are unique in their ability to alter their environment with the conscious purpose of increasing its carrying capacity. In studies of humans and some animals (15, 23, 24, 27, 45), artificial gravity (AG) or hypergravity has been shown to positively affect bone (or related markers), and for this reason, among other benefits, it has been brought to the attention of the … The loss of bone and muscle mass, change in cardiac performance, variation in behavior, and body-wide alterations initiated by a changing nervous system are some of the most apparent and potentially detrimental effects … No Comments on Positive and negative effects of population growth Here, population growth refers to the increase in the number of individuals across the world. The initial condition is a symmetric distribution of the density of inhabitants that is uniform except in the central three cells. The ultimate effect of these changes on our carrying capacity is unknown. Clearly blood flow directly affects osteoblast populations and bone mass.
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