Population Density Distribution Research Articles

Does High Spatial Density Imply High Population Density? Spatial Mechanism of Population Density Distribution Based on Population–Space Imbalance

Numerous studies have suggested a positive correlation between spatial and population densities. However, few have systematically conducted quantitative analysis and deciphered the detailed correlation in block scale. Here, we construct a population–space correlation algorithm to quantify and compare the correlation between mobile phone signalling data and vector spatial data and identify blocks with uneven population density. We analyse the influences of various urban spatial characteristics on population density and the distribution characteristics of the identified city blocks. Changzhou City, China, was selected as the study case. The results indicate that (1) population density distribution is unbalanced only when spatial density exceeds a critical value, reflecting the level and sphere of influence of blocks with varying spatial densities; (2) low population density distribution is concentrated in the zonal space, along the boundary between primary and secondary urban centres; (3) spatial characteristics affecting population density distribution vary with the type of block, and the green landscape’s attractiveness is reduced. Our study provides a novel perspective on quantifying the link between urban form and population distribution. It can help decision-makers and planners in accurately recommending urban intervention in population density distribution by adjusting the spatial morphology and promoting rational use of urban public resources.

Population Structure of Three Provenances of Vitis tiliifolia (Humb. & Bonpl. ex Schult.) in the Central Zone of the State of Veracruz, México

The objective of this work is to show the population structure of V. tiliifolia under natural conditions. The study was conducted in three municipalities in the state of Veracruz, México; through transects of 20 × 100 m (2000 m2), the population structure, density and spatial distribution of natural populations were determined. The edaphic and climatic factors were also determined through soil analysis and database consultation. The data were analyzed by ANOVA. The population structure for the three selected sites showed a type II curve, that is, mostly adults with few seedlings and juveniles. The spatial distribution presented an aggregate type pattern for the seedling and juvenile state categories, as well as a random type pattern for adults. The CPA allows us to visualize that there is a strong correlation between the chemical variables and the availability of some micronutrients; male individuals are the variable that explain the population structure. This shows that the low density of individuals in their early stages, together with the longevity of adult individuals and factors such as low rainfall, forest fires, reproductive biology and exploitation of the species put the persistence of populations at risk in this region.

The Population Density Map of the Greater Cairo Region Comparison of 2017 Choropleth Map and Dasymetric Map

Although the choropleth method is considered among the easiest cartographic methods, it lacks accurate representation of the real population density. In this regard, dasymetric maps offer the better alternative, especially for heterogonous spaces and those exhibit intense spatial dynamic, like the Greater Cairo Region, which has the highest population and population density among various Egyptian governorates. The current study aims mainly at comparing the dasymetric mapping technique with the choropleth mapping technique for studying the population density in the Greater Cairo Region. To this end, the satellite image processing and ArcGIS (version 10.6.1) were used. For instance, it was found, in the choropleth map, that the population density category ranged from 161.415 to 270.922 person per km2 occupied 1% of the total area of 1481 km2; whereas, in the dasymetric map, the population density category ranged from 139.986 to 761044 person per km2 concentrated in only 0.4% of the total area of 648 km2. Thus it is clear that the dasymetric mapping technique is more representative of the realistic population density distribution, because it eliminates all land uses except the residential land use. Conclusively, it is highly recommended to use the dasymetric mapping technique rather than the choropleth method.

Beyond the Backyard: GIS Analysis of Public Green Space Accessibility in Australian Metropolitan Areas

During times of stress and social pressure, urban green space provides social, cultural, and economic resources that help individuals and communities cope. Green space accessibility is, therefore, an important indicator related to people’s health and welfare. However, green space accessibility is not even throughout urban areas, with some areas better served with green space than others. Green space patterning is, therefore, a major environmental justice challenge. This research uses GIS approaches to analyze and understand urban green space access of urban communities in the Australian metropolitan areas of Adelaide, Melbourne, Sydney, and Brisbane. We calculate indicators to describe green space access in relation to different green space patterns within different metropolitan zones, including the inner urban, suburban, and peri urban. We use the best available open data from the Australian census of 2017 to calculate green space accessibility. Our results describe the relationship between population density and green space distribution and patterning in the four metropolitan areas. We find that even cities which are generally thought of as liveable have considerable environmental justice challenges and inequity and must improve green space access to address environmental inequity. We also find that a range type of measures can be used to better understand green space accessibility. Accessibility varies greatly both within metropolitan areas and also from city to city. Through improving our understanding of the green space accessibility characteristics of Australian metropolitan areas, the result of this study supports the future planning of more just and equal green cities.

Low-Orbit Large-Scale Communication Satellite Constellation Configuration Performance Assessment

A constellation configuration performance evaluation method is proposed for the performance evaluation of the low-orbit large-scale communication satellite constellations. The practicality and feasibility analysis of the constellation configuration is mainly studied from the constellation coverage performance. Based on the consideration of the coverage performance of the LEO satellite constellation, four simulation models are established for the single coverage rate, observation elevation angle, number of visible satellites under different observation elevation angles, and coverage efficiency of the constellation. A population distribution density function is established according to the characteristics of population distribution to find the average minimum observation elevation angle and the average number of visible satellites under the population distribution. The evaluation method is applied to three typical low-orbit large-scale communication satellite constellations, Telesat, OneWeb, and Starlink, to derive the coverage performance index values of each constellation and to compare and analyze the characteristics of the three constellations. The results show that the evaluation method can evaluate the configuration performance of different types of LEO large-scale constellations and provide a basis and reference for the optimal design and evaluation of future LEO large-scale constellation configurations.

Flight Scheduling and Fleet Sizing for an Airport Shuttle Air Taxi Service

A multicommodity network flow framework for optimal flight scheduling for an envisioned airport shuttle air taxi service is presented. The framework includes a trip generation model that simulates requests from individuals who travel to and from the airport and are willing to pay for the travel time savings associated with an airport shuttle air taxi service. The framework can be used to determine the fleet size required to satisfy a given user demand and to assess how an operator’s profitability can be influenced by multiple factors, including the population density and income distribution in a metropolitan area, fleet size, ticket price, and air taxi operating costs. The results for an example business airport shuttle service to and from Atlanta Hartsfield Jackson International Airport suggest that a viable business case is possible using electric vertical take-off and landing aircraft. For example, the results for this Atlanta case study indicate that it is possible to have profitable business use case with positive cash flow with a four-seat aircraft with a 60-mile design range and a 150 mph cruise speed using a fleet size of five aircraft at a price point of $5 per passenger-mile during near-term small-scale operations.

Land Use Change and Its Driving Factors in the Rural–Urban Fringe of Beijing: A Production–Living–Ecological Perspective

Production–Living–Ecological Space (PLES) is a useful tool to identify land use status patterns and optimize land resource allocation. In this study, the spatial econometric model was chosen to analyze the driving factors of land use change in Chaoyang District, part of the rural–urban fringe in Beijing, from the perspective of PLES evolution, from 2005 to 2020. The results showed the following: (1) Production Space (PS) to Living-Non-Farm Production Space (LNPS) has been the most significant conversion process of PLES since 2005, making LNPS the PLES type with the highest proportion in the study area. (2) With the spatial order from near-to-far from the city center, the scale of PS was reduced and concentrated, Ecological Space (ES) was formed in a green belt at the periphery of Beijing, Eco-Agricultural Production Space (EAPS) and Living-Agricultural Production Space were rapidly reduced, and LNPS was rapidly expanded in the point-line-plane order. (3) The PS to LNPS conversion was mainly driven by economic development and industrial structure upgrades, while the PS to ES conversion was mainly due to the distribution of population density and also industrial structures. The conversion of EAPS to LNPS was driven by the increase of the urbanization rate and economic growth. This study confirmed the policy-driven effect of the conversion from PS to ES. Due to the “Concentric Circle” spatial structure of Beijing, the conversion of PLES is generally related to the distance from the city center.

Land Surface Temperature and its Relationship to Population Density

Population density due to urbanization contributes to the SUHI phenomenon and urban climate change. Understanding the SUHI phenomenon that brings enormous negative impacts to the environment and human life, Land Surface Temperature (LST) assessment is essential for creating a feasible and livable city. By utilizing the data of 1999 and 2018, this study aims to assess the LST value and its relationship to population density in Tanjungpinang city over two decades. As an island, Tanjungpinang has a vulnerability to SUHI and the climate change phenomenon. This study applied GIS and remote sensing models based on the mathematical formula of digital remote sensing images to calculate the LST value, and the relationship between LST and population density was examined using correlation analyses with Microsoft Excel. The results showed that Tanjungpinang city had increased 3.5oC in LST and 94.80% in density population over two decades. SUHI phenomenon has occurred during this period. It also indicated that there was a significant relationship between population density and LST. The LST spatial pattern spread from west to east of Tanjungpinang city was in line with the population density distribution pattern. The area with the highest percentage of population density addition and experienced the highest LST was Tanjungpinang Barat District. This study considers local governments to create effective population control and adaptive planning strategies for SUHI phenomenon mitigation.

Geospatial model of COVID-19 spreading and vaccination with event Gillespie algorithm

We have developed a mathematical model and stochastic numerical simulation for the transmission of COVID-19 and other similar infectious diseases that accounts for the geographic distribution of population density, detailed down to the level of location of individuals, and age-structured contact rates. Our analytical framework includes a surrogate model optimization process to rapidly fit the parameters of the model to the observed epidemic curves for cases, hospitalizations, and deaths. This toolkit (the model, the simulation code, and the optimizer) is a useful tool for policy makers and epidemic response teams, who can use it to forecast epidemic development scenarios in local settings (at the scale of cities to large countries) and design optimal response strategies. The simulation code also enables spatial visualization, where detailed views of epidemic scenarios are displayed directly on maps of population density. The model and simulation also include the vaccination process, which can be tailored to different levels of efficiency and efficacy of different vaccines. We used the developed framework to generate predictions for the spread of COVID-19 in the canton of Geneva, Switzerland, and validated them by comparing the calculated number of cases and recoveries with data from local seroprevalence studies.

A multicriteria decision analysis framework to measure equitable healthcare access during COVID-19

The ongoing novel coronavirus (COVID-19) pandemic has highlighted the need for individuals to have easy access to healthcare facilities for treatment as well as vaccinations. The surge in COVID-19 hospitalizations during 2020 also underscored the fact that accessibility to nearby hospitals for testing, treatment and vaccination sites is crucial for patients with fever or respiratory symptoms. Although necessary, quantifying healthcare access is challenging as it depends on a complex interaction between underlying socioeconomic and physical factors. In this case study, we deployed a Multi Criteria Decision Analysis (MCDA) approach to uncover the barriers and their effect on healthcare access. Using a least cost path (LCP) analysis we quantified the costs associated with healthcare access from each census block group in the Los Angeles metropolitan area (LA Metro) to the nearest hospital. Social vulnerability reported by the Centers for Disease Control and Prevention (CDC), the daily number of COVID-19 cases from the Los Angeles open data portal and built environment characteristics (slope of the street, car ownership, population density distribution, walkability, traffic collision density, and speed limit) were used to quantify overall accessibility index for the entire study area. Our results showed that the census block groups with a social vulnerability index above 0.75 (high vulnerability) had low accessibility owing to the higher cost of access to nearby hospitals. These areas were also coincident with the hotspots for COVID-19 cases and deaths which highlighted the inequitable exposure of socially disadvantaged populations to COVID-19 infections and how the pandemic impacts were exacerbated by the synergistic effect of socioeconomic status and built environment characteristics of the locations where the disadvantaged populations resided. The framework proposed herein could be adapted to geo-target testing/vaccination sites and improve accessibility to healthcare facilities in general and more specifically among the socially vulnerable populations residing in urban areas to reduce their overall health risks during future pandemic outbreaks.

载畜率对荒漠草原冷蒿植物种群密度及其空间分布的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 载畜率对荒漠草原冷蒿植物种群密度及其空间分布的影响 DOI: 10.5846/stxb202102060390 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（31760143）；内蒙古重大科技专项（ZDZX2018020）；内蒙古自治区科技成果转化项目（2020CG0013）；科技成果转化项目（2019CG069） Effects of stocking rate on population density and spatial distribution of Artemisia frigida in desert steppe Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:载畜率是衡量草原生产能力的指标之一，研究荒漠草原冷蒿（Artemisia frigida）植物种群在不同载畜率下的耐牧程度和空间分布特征，对退化草原的恢复具有重要的指导意义。以短花针茅荒漠草原优势种冷蒿为研究对象，在4个不同载畜率放牧试验设计（对照区CK （0只/hm2）、轻度放牧区LG （0.93只/hm2）、中度放牧区MG （1.82只/hm2）和重度放牧区HG （2.71只/hm2））小区中选择代表性样地（面积为40m×40m），采用机械取样法进行取样，记录冷蒿植物种群的密度，使用SAS 9.4软件对其进行描述性统计和方差分析，并用地统计学软件GS+9.0进行空间异质性统计分析。结果表明：荒漠草原优势种冷蒿密度、出现频率和单位均值上的变异值随载畜率增大都明显下降，其植物种群空间分布的决定性因素随载畜率增大由结构性因素转变为随机性因素。LG和HG处理区的空间自相关距离较大，但这两者表现结果的影响因素存在差异。在CK和HG区，冷蒿空间分布斑块化较为明显，LG区的冷蒿空间分布的特征表现为带状分布，MG区冷蒿空间分布形成了一处大的条带和零星的几块斑块。基于上述研究结果可以得出，随着载畜率增加，荒漠草原冷蒿种群密度下降，空间分布趋于单一化，导致冷蒿的生产力下降，进而影响草地的可持续利用。 Abstract:Stocking rate is one of the most important indicators to measure the productivity of grassland. Study on the grazing tolerance and spatial distribution characteristics of Artemisia frigida population under different stocking rates in desert steppe has significant effects for the restoration of the degraded grassland. The experiment design selected Artemisia frigida, a dominant species in Stipa breviflora desert steppe as the research object, which conducted with four different stocking rates (CK, 0 sheep unit hm-2; LG, 0.93 sheep unit hm-2; MG, 1.82 sheep unit hm-2; and HG, 2.71 sheep unit hm-2), and the representative sample plot (40 m×40 m) with the same terrain in each treatment was selected. The plant population density of Artemisia frigida is recorded by mechanical sampling method. Then, the descriptive statistics and variance analysis were performed by SAS9.4 software, and the spatial heterogeneity was analyzed using statistical software GS+9.0. The results showed that the density, frequency of occurrence, and the variation of mean value of Artemisia frigida decreased significantly with the increase of stocking rate. The spatial distribution decisive factor of plant population changed from structural factor to random factor with the increase of stocking rate. The fractal dimension value D0 was ranked from large to small under different stocking rates is CK>HG>MG>LG, under different grazing conditions, the values of fractal dimension were between 1.700 and 2.000, indicating that the spatial distribution of these four regions with different stocking rates was relatively uniform. The spatial auto-correlative distances in LG and HG treatments were relatively larger than other treatments, which caused by different impact factors, LG area was significantly affected by random factors, and HG area was significantly affected by structural factors. With the increase of stocking rate, the spatial correlation of Artemisia frigida gradually weakened. Artemisia frigida has different spatial states in different stocking rates, the spatial distribution of Artemisia frigida were patchy in CK and HG treatments, while it was characterized by banded distribution in LG treatment, and it formed a large strip and scattered patches in MG treatment, the density distributions of LG and MG were similar, but the uniformity of MG is greater than LG treatment. Based on the research results above mentioned, we can conclude that the population density of Artemisia frigida decreased and the spatial distribution tended to be simplified, resulted in the decrease of productivity of Artemisia frigida with the increase of stocking rate, which affected the sustainable utilization of grassland in the desert steppe. 参考文献 相似文献 引证文献

La cabra montés coloniza la Vega de Granada, una nueva especie para Sierra Elvira (España)

The Iberian ibex (Capra pyrenaica) is an endemic species of the Iberian Peninsula that is expanding throughout the province of Granada (Andalucía). Historical records of this species in the Sierra Elvira massif, in the Vega de Granada, are missing. This recent permanent establishment of this species in the study area allows us to examine different demographic parameters from this population (density, reproductive index, sex ratio and age distribution). To approach this goal, we sampled by the Distance Sampling method this ibex population during the spring of 2019. Besides, to evaluate the use of the space and determine the range size, we captured and marked one individual. Although the preliminary basis of the study, the results define several population parameters of this newly established ibex population. Overall, this study can be used to develop a proper management program of this population that includes monitoring, habitat adaptation and a harvest control plan.

Effects of Urbanization on the Dynamics and Equity of Access to Urban Parks from 2000 to 2015 in Beijing, China

Urban parks provide multiple ecosystem services as an important element of the urban space and improve human health and wellbeing. This study used the Gaussian-based 2SFCA method to evaluate the spatiotemporal distribution of and changes in park accessibility within the Sixth Ring Road in Beijing over 15 years. The study also used bivariate correlation analysis to analyze the relationship between urbanization factors and park access. The results showed that the overall park accessibility in both quantity and proximity had increased from 2000 to 2015, but there were still certain areas (percentage) that had limited access to parks. The inequity of distribution in park accessibility had been detected accompanying the rapid increase in park quantity in 2015. Furthermore, the development of urban parks mismatched that of urbanization in terms of urban land increase. The correlation between accessibility changes and population urbanization is not significant. Proper urban green space planning based on the distribution of population density and urban land use is indispensable in avoiding the aggravation of inequity in the process of urban expansion. This study contributes to the assessment of the current park allocation efficiency and helps urban planners and policymakers make prompt adjustments in the rapidly urbanizing process.

Molecular characteristics of Legionella pneumophila in shower water of public places in Ma'anshan city from 2019 to 2020

Objective: To understand the epidemiological and pathogenic characteristics of Legionella pneumophila in shower water of public places in Ma'anshan City from 2019 to 2020, and to provide scientific basis for further prevention and control of legionellosis. Methods: From 2019 to 2020, according to population density distribution and business scale of bathing places in the main urban area of Ma'anshan City (Huashan District and Yushan District), 8 public bathing places (including 3 large, 3 medium and 2 small) were selected to collect 308 shower water and water storage pool water samples (294 shower water samples and 14 water storage pool water samples). After the collected water samples were treated, cultured, isolated and identified, the type characteristics of Legionella pneumophila were analyzed. Results: Legionella pneumophila were detected in 120 water samples among 308 shower water and water storage pool water samples, with an overall positive rate of 39.0% (120/308). A total of 154 Legionella pneumophila strains were detected, including 10 different serotypes, predominated by serotype 1 (LP1) and serotype 3 (LP3), accounting for 40.9% (63/154) and 22.7% (35/154). Among 154 strains of Legionella pneumophila, 23 strains of Legionella pneumophila were positive for all 14 virulence genes, accounting for 14.9% (23/154), including 19 serotype 1 (LP1) and 4 serotype 8 (LP8). Pulsed field gel electrophoresis (PFGE) cluster analysis of 154 Legionella pneumophila strains showed 60 different patterns. Conclusion: Legionella pneumophila was seriously polluted in the shower water environment of public places in Ma, anshan City. The serotypes are widely distributed and the virulence of the strains is strong. The results of molecular typing show that these strains have genetic diversity.

Benthic foraminiferal assemblages and environmental drivers along the Kveithola Trough (NW Barents Sea)

We describe the population density, biodiversity and vertical distribution in the sediment of benthic foraminifera, and their relationship to environmental parameters, in the Kveithola Trough (NW Barents Sea). Two staining methods, Cell Tracker Green (CTG) and Rose Bengal (RB), were used to distinguish between living and dead tests. CTG proved to be more effective than RB, and we therefore used this approach to document faunal assemblage variability along a transect of the Trough. The outer shelf shows a diverse benthic foraminiferal assemblage suggesting an oxygenated and oligotrophic environment. The central part appears to be a disturbed area due to rapid circulation changes and organic matter burial in sediments where opportunistic foraminifera colonize only the first centimetres. In contrast, the inner part of the Trough seems to be a stressed environment where species associated with organic-rich sediment and oxygen-depleted environments dominate the living assemblage. At all sites, delicate monothalamids species form part of the assemblage. The peculiar geomorphological and environmental conditions of this area, and the high regional primary and secondary production, are key drivers of foraminiferal assemblage distribution. • This work analyses the living benthic foraminifera of the Kveithola Trough. • The peculiar conditions shape the living benthic foraminiferal structure. • Faunal distribution varies along the longitudinal transect of the area. • The main determining factor in the diversity is the organic matter concentration. • CTG method is appropriate to document the vitality of foraminifera in this area.

The Relationship between Urban Population Density Distribution and Land Use in Guangzhou, China: A Spatial Spillover Perspective.

Urban population density distribution contributes towards a deeper understanding of peoples’ activities patterns and urban vibrancy. The associations between the distribution of urban population density and land use are crucial to improve urban spatial structure. Despite numerous studies on population density distribution and land use, the significance of spatial dependence has attained less attention. Based on the Baidu heat map data and points of interests data in the main urban zone of Guangzhou, China, the current paper first investigated the spatial evolution and temporal distribution characteristics of urban population density and examined the spatial spillover influence of land use on it through spatial correlation analysis methods and the spatial Durbin model. The results show that the urban population density distribution is characterized by aggregation in general and varies on weekends and weekdays. The changes in population density within a day present a trend of “rapid growth-gentle decline-rapid growth-rapid decline”. Furthermore, the spatial spillover effects of land use exist and play the same important roles in population density distribution as the direct effects. Additionally, different types of land use show diverse direct effects and spatial spillover effects at various times. These findings suggest that balancing the population density distribution should consider the indirect effect from neighboring areas, which hopefully provide implications for urban planners and policy makers in utilizing the rational allocation of public resources and regarding optimization of urban spatial structure.

Spatializing inequality across residential built-up types: A relational geography of urban density in São Paulo, Brazil.

Overcrowding in informal housing is a core problem in international development debates, whereby slum upgrading is viewed as a dominant policy to integrate formal and informal areas. Conceptually, challenges to socio-spatial integration are associated with unbalanced development processes of urban de- and re-densification beyond the housing level. However, a lack of empirical understanding of these processes limits the case for redistributive land use policies to complement slum upgrading. To address this gap, our study adopts an exploratory approach, applying GIS-based techniques to population census and open data on land use in São Paulo, Brazil, in order to analyze the distribution of population densities across residential built-up types in informal and informal areas, although there are constrains related to small-scale spatial data sources on urban density. This shows that informal settlements are indeed the densest residential built-up type in the city while revealing the underlying spatial inequality between informal settlements and low-rise, high-standard residential areas. We suggest that more emphasis be placed on the design and implementation of redistributive policies to avoid spatialized forms of inequality associated with uneven urban development. This will ensure the spatial and social integration of urban areas.

Spiral waves in population density distributions of invasive pests in warm-temperate deciduous forest ecosystems

Globally, forests are increasingly being affected by invasive alien pests, some of which have caused wholesale destruction of trees. Recent research suggests that, in the United States, large-scale forests have been invaded by an astonishing number (> 450) of tree-feeding pests. Invasive alien pests always induce cascading ecological effects, leading to harmful socioeconomic consequences; however, the prevention and control of invasive alien pests in forests have been facing significant challenges worldwide. Here, we studied theoretically the control of invasive nonnative pests in warm-temperate deciduous forest ecosystems by their natural enemies (biological control), and controlled them to an extent that ecosystems can bear. We obtained a novel type of spiral wave in the spatial distribution of population density, and also observed a transition phenomenon between spiral wave and anti-spiral wave, which is explained by a mathematical analysis. Specifically, the formation of this type of spiral wave is attributed to the directional transformation of states between the period-5 orbits under the impact of diffusion transport. And the transition phenomenon is caused by changes of relative positions of the period-5 orbits in phase space. Moreover, we also found a novel type of instability of spiral wave, which includes a birth-growth-death process of spiral fragments. The findings provide possible regularities in the process of biological control of invasive alien pests in the complex and changeable forest ecosystems, which may guide actual biological control projects.

Association Between Genetic Risk for Psychiatric Disorders and the Probability of Living in Urban Settings

Urban residence has been highlighted as an environmental risk factor for schizophrenia and, to a lesser extent, several other psychiatric disorders. However, few studies have explored genetic effects on the choice of residence. To investigate whether individuals with genetic predisposition to a range of psychiatric disorders have an increased likelihood to live in urban areas. A cross-sectional retrospective cohort study including genotypes, address history, and geographic distribution of population density in the UK based on census data from 1931-2011 was conducted. Polygenic risk score (PRS) analyses, genome-wide association studies, genetic correlation, and 2-sample mendelian randomization analyses were applied to 385 793 UK Biobank participants with self-reported or general practitioner registration-based address history. The study was conducted from February 2018 to May 2021, and data analysis was performed from April 2018 to May 2021. Population density of residence at different ages and movement during the life span between urban and rural environments. In this cohort study of 385 793 unrelated UK Biobank participants (207 963 [54%] were women; age, 37-73 years; mean [SD], 56.7 [8] years), PRS analyses showed significant associations with higher population density across adult life (age 25 to >65 years) reaching highest significance at the 45- to 55-year age group for schizophrenia (88 people/km2; 95% CI, 65-98 people/km2), bipolar disorder (44 people/km2; 95% CI, 34-54 people/km2), anorexia nervosa (36 people/km2; 95% CI, 22-50 people/km2), and autism spectrum disorder (35 people/km2; 95% CI, 25-45 people/km2). The schizophrenia PRS was also significantly associated with higher birthplace population density (37 people/km2; 95% CI, 19-55 people/km2; P = 8 × 10-5). Attention-deficit/hyperactivity disorder PRS was significantly associated with reduced population density in adult life (-31 people/km2; 95% CI, -42 to -20 people/km2 at age 35-45 years). Individuals with higher PRS for schizophrenia, bipolar disorder, anorexia nervosa, and autism spectrum disorder and lower PRS for attention-deficit/hyperactivity disorder preferentially moved from rural environments to cities (difference in PRS with Tukey pairwise comparisons for schizophrenia: 0.05; 95% CI, 0.03 to 0.60; bipolar disorder: 0.10; 95% CI, 0.08 to 0.13; anorexia nervosa: 0.05; 95% CI, 0.03 to 0.07; autism spectrum disorder: 0.04; 95% CI 0.03 to 0.06; and attention-deficit/hyperactivity disorder: -0.09, 95% CI, -0.12 to -0.06). Genetic correlation results were largely consistent with PRS analyses, whereas mendelian randomization provided support for associations between schizophrenia and bipolar disorder and living in high population-density areas. These findings suggest that a high genetic risk for a variety of psychiatric disorders may affect an individual's choice of residence. This result supports the hypothesis of genetic selection of an individual's environment, which intersects the traditional gene-environment dichotomy.

Population distribution characteristics and its relationship with natural factors in karst mountainous areas of Northwest Guangxi

The smallest administrative unit of the sixth national census-township (town) is selected as the basic unit, the population spatial distribution characteristics at the township (town) level in karst mountainous areas of northwest Guangxi are analyzed by using Lorenz curve and spatial correlation analysis method, and the influence intensity of natural factors on regional population spatial distribution is detected by using geographic detector method. The results show that: 1. the spatial distribution of population at the township (town) level has the characteristics of imbalance, showing generally significant positive correlation and certain aggregation; 2. there are significant differences in the impact of the spatial distribution of various natural factors on the population distribution. For the towns without karst distribution in the northwest and central south of the study area, the population density increases with the increase of factors conducive to human residence, but the average population density is only 79 people / km2. In the towns with karst distribution in the East and south, the spatial distribution of population density and natural factors is not a simple increase or decrease relationship, but fluctuates with the change of karst distribution area. 3. The factor detection results of the geographic detector show that the altitude has the greatest impact on the spatial distribution of population. The interactive detection results show that the impact intensity of any two natural factors after superposition and interaction presents nonlinear enhancement and two factor enhancement. It can be seen that the karst mountain area in northwest Guangxi is similar to other areas. Altitude is one of the main factors affecting the spatial distribution of population, but the river network density and unique geological landform of karst mountain area have a strong catalytic effect on the spatial distribution of population. The superposition and interaction with other factors can further strengthen the impact on population distribution.