Urban Systems: Understanding and Predicting the Spatial Distribution of China's Population

2021 ◽  
Vol 29 (4) ◽  
pp. 35-62
Author(s):  
Pengfei Li ◽  
Ming Lu
Keyword(s):  
Spatial Distribution ◽  
Urban Systems

Non-linear interactions of urban and freshwater systems: Exploring implications for sustainability and water planning and management

2020 ◽  
Author(s):  
Héctor Angarita ◽  
Vishal Mehta ◽  
Efraín Domínguez
Keyword(s):  
Spatial Distribution ◽  
Urban Areas ◽  
Human Population ◽  
Urban Population ◽  
Urban Systems ◽  
Resource Base ◽  
Freshwater Systems ◽  
Non Linear ◽  
Freshwater System

<p>Human population is progressing into a predominantly urban configuration. Currently, 3.5 billion people – 55% of the total human population – live in urban areas, with an increase to 6.68 billion (68%) projected by 2050. In this progressively more populated world, a central issue of sustainability assessments is understanding the role of cities as entities that, despite their comparatively small physical footprint (less than 0.5% of the global area) demand resources at regional and global scales.</p><p>Many of the resources that sustain urban population directly depend on the freshwater system: from direct fluxes from/to the immediate environment of cities for water supply or waste elimination, to water-dependent activities like biomass (food, biofuels, fibers) and energy production. Urban and freshwater system interactions are subject to multiple sources of non-linearity. Factors like the patterns of size or spatial distribution and interconnection of groups of cities; or the nested and hierarchical character of freshwater systems, can vastly influence the amount of resources required to sustain and grow urban population; likewise, equivalent resource demands can be met through different management strategies that vary substantially in their cumulative pressure exerted on the freshwater system.</p><p>Here we explore the non-linear character of those interactions, to i. identify water management options to avoid, minimize or offset regional impacts of growing urban populations, and ii. explore long term implications of such non-linearities in sustained resource base of urban areas. We propose a framework integrating three elements: 1. properties of the size and spatial distribution of urban center sizes, 2. scaling regime of urban energy resource dependencies, and 3. scaling regime of associated physical and ecological impacts in freshwater systems.</p><p>An example of this approach is presented in a case study in the Magdalena River Basin – MRB (Colombia). The basin covers nearly one quarter of Colombia’s national territory and provides sustenance to 36 million people, with three quarters of basin inhabitants living in medium to large urban settlements of populations of 12 000 or more inhabitants and 50% concentrated in the 15 largest cities. The case study results indicate that freshwater-mediated resource dependencies of urban population are described by a linear or super-linear regime that indicates a lack of scale economies, however, freshwater systems’ capacity to assimilate those resource demands is characterized by a sublinear regime. As a result, current practices and technological approaches to couple freshwater and urban systems will not be able to withstand the resource demands of mid-term future population scenarios.  Our approach allows to quantify the projected gaps to achieve a sustained resource base for urban systems in MRB.</p>

scholarly journals Modelos de Desenvolvimento Regional e Sistemas Urbanos: Portugal, visão integrada / Regional Development Models and Urban Systems: Portugal, integrated approach

Redes ◽  
2016 ◽  
Vol 22 (1) ◽  
pp. 280
Author(s):  
Carlos Gonçalves
Keyword(s):  
Spatial Distribution ◽  
Regional Development ◽  
Integrated Approach ◽  
Urban Systems ◽  
Development Models ◽  
The Future

Resumo Neste artigo, analisam-se os sistemas urbanos representados nos Planos Regionais de Ordenamento do Território em Portugal Continental. A espacialização dos sistemas urbanos regionais reproduz, quer as dinâmicas de desenvolvimento existentes, quer a natureza das propostas formuladas pelo conjunto de entidades que têm responsabilidades de projetar o futuro destas regiões. Propõe-se um exercício de agregação das propostas e, através dele, apresenta-se uma síntese das estruturas definidoras do desenvolvimento do país. Abstract In this article we analyze the urban systems represented in Portuguese Regional Spatial Plans. The spatial distribution of regional urban systems reproduces the development dynamics consolidated and the nature of the proposals made by the group of entities that have responsibilities to design the future of these regions. At the end, we present an exercise that combines the proposals and through it, we present an overview of the structures that organize the development of the country.

scholarly journals Recent demographic-economic processes in the Belgrade agglomeration

2010 ◽  
Vol 90 (1) ◽  
pp. 215-235 ◽  
Author(s):  
Gordana Vojkovic ◽  
Radmila Miletic ◽  
Dragana Miljanovic
Keyword(s):  
Spatial Distribution ◽  
Structural Features ◽  
Urban Systems ◽  
Urban Region ◽  
Economic Changes ◽  
Modern Development ◽  
Global Trend ◽  
Development Processes ◽  
Basic Characteristics ◽  
Demographic Growth

In this paper, basic characteristics of demographic and economic changes in the area of Belgrade agglomeration in the second half of 20th century has been researched, and a global trend of their establishments and motions has been indicated. Changes of territorial arrangement, spatial distribution and structural features of population, within the agglomeration itself, were in close interaction with directions of development and expansion of urban region. Belgrade agglomeration development follows several stages in its physiognomic-spatial, economic and demographic growth, whereby the migrations, as in cases of all large urban systems, had special influence on growth and structural features of population. In this paper, modern development processes and their effects on demographic growth have been emphasized. .

Lithography below 100 nm

1983 ◽  
Vol 41 ◽  
pp. 96-99
Author(s):  
L. D. Jackel
Keyword(s):  
Spatial Distribution ◽  
Electron Beam ◽  
Electron Scattering ◽  
Electron Beam Lithography ◽  
Substrate Material ◽  
Local Electron ◽  
Electron Dose ◽  
Positive Resist ◽  
Exposure Process

Most production electron beam lithography systems can pattern minimum features a few tenths of a micron across. Linewidth in these systems is usually limited by the quality of the exposing beam and by electron scattering in the resist and substrate. By using a smaller spot along with exposure techniques that minimize scattering and its effects, laboratory e-beam lithography systems can now make features hundredths of a micron wide on standard substrate material. This talk will outline sane of these high- resolution e-beam lithography techniques.We first consider parameters of the exposure process that limit resolution in organic resists. For concreteness suppose that we have a “positive” resist in which exposing electrons break bonds in the resist molecules thus increasing the exposed resist's solubility in a developer. Ihe attainable resolution is obviously limited by the overall width of the exposing beam, but the spatial distribution of the beam intensity, the beam “profile” , also contributes to the resolution. Depending on the local electron dose, more or less resist bonds are broken resulting in slower or faster dissolution in the developer.

SEM evaluation of the TEM cold-stage double-film specimen

1984 ◽  
Vol 42 ◽  
pp. 272-273
Author(s):  
Jayesh Bellare
Keyword(s):  
Spatial Distribution ◽  
Sample Preparation ◽  
Sample Thickness ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Liquid Sample ◽  
Thin Specimen ◽  
Sample Preparation Technique ◽  
Cold Stage ◽  
Film Specimen

Seeing is believing, but only after the sample preparation technique has received a systematic study and a full record is made of the treatment the sample gets.For microstructured liquids and suspensions, fast-freeze thermal fixation and cold-stage microscopy is perhaps the least artifact-laden technique. In the double-film specimen preparation technique, a layer of liquid sample is trapped between 100- and 400-mesh polymer (polyimide, PI) coated grids. Blotting against filter paper drains excess liquid and provides a thin specimen, which is fast-frozen by plunging into liquid nitrogen. This frozen sandwich (Fig. 1) is mounted in a cooling holder and viewed in TEM.Though extremely promising for visualization of liquid microstructures, this double-film technique suffers from a) ireproducibility and nonuniformity of sample thickness, b) low yield of imageable grid squares and c) nonuniform spatial distribution of particulates, which results in fewer being imaged.

Macroprobe Mode for the Study of Segregation in Steels

1990 ◽  
Vol 48 (2) ◽  
pp. 260-261
Author(s):  
Auclair Gilles ◽  
Benoit Danièle
Keyword(s):  
Mechanical Properties ◽  
Spatial Distribution ◽  
High Performance ◽  
Volume Fraction ◽  
Sheet Steel ◽  
Acquisition Time ◽  
Chemical Information ◽  
X Ray ◽  
Accurate Quantitative Analysis ◽  
Optical Micrographs

During these last 10 years, high performance correction procedures have been developed for classical EPMA, and it is nowadays possible to obtain accurate quantitative analysis even for soft X-ray radiations. It is also possible to perform EPMA by adapting this accurate quantitative procedures to unusual applications such as the measurement of the segregation on wide areas in as-cast and sheet steel products.The main objection for analysis of segregation in steel by means of a line-scan mode is that it requires a very heavy sampling plan to make sure that the most significant points are analyzed. Moreover only local chemical information is obtained whereas mechanical properties are also dependant on the volume fraction and the spatial distribution of highly segregated zones. For these reasons we have chosen to systematically acquire X-ray calibrated mappings which give pictures similar to optical micrographs. Although mapping requires lengthy acquisition time there is a corresponding increase in the information given by image anlysis.

Ultrastructural analysis of the spatial distribution of MRNA

1992 ◽  
Vol 50 (1) ◽  
pp. 552-553
Author(s):  
Gary Bassell ◽  
Robert H. Singer
Keyword(s):  
Electron Microscopy ◽  
Spatial Distribution ◽  
In Situ Hybridization ◽  
High Resolution ◽  
Nucleic Acids ◽  
Colloidal Gold ◽  
Dna Probe ◽  
Nucleotide Analogs ◽  
Gold Particles

We have been investigating the spatial distribution of nucleic acids intracellularly using in situ hybridization. The use of non-isotopic nucleotide analogs incorporated into the DNA probe allows the detection of the probe at its site of hybridization within the cell. This approach therefore is compatible with the high resolution available by electron microscopy. Biotinated or digoxigenated probe can be detected by antibodies conjugated to colloidal gold. Because mRNA serves as a template for the probe fragments, the colloidal gold particles are detected as arrays which allow it to be unequivocally distinguished from background.

Membrane microdomains: lessons from microscopy

1995 ◽  
Vol 53 ◽  
pp. 776-777
Author(s):  
J.M. Robinson ◽  
J.M Oliver
Keyword(s):  
Spatial Distribution ◽  
Plasma Membrane ◽  
Epithelial Cells ◽  
Plasma Membranes ◽  
Cell Types ◽  
Imaging Modalities ◽  
Membrane Microdomains ◽  
Membrane Domains ◽  
Lateral Heterogeneity ◽  
Functional Importance

Specialized regions of plasma membranes displaying lateral heterogeneity are the focus of this Symposium. Specialized membrane domains are known for certain cell types such as differentiated epithelial cells where lateral heterogeneity in lipids and proteins exists between the apical and basolateral portions of the plasma membrane. Lateral heterogeneity and the presence of microdomains in membranes that are uniform in appearance have been more difficult to establish. Nonetheless a number of studies have provided evidence for membrane microdomains and indicated a functional importance for these structures.This symposium will focus on the use of various imaging modalities and related approaches to define membrane microdomains in a number of cell types. The importance of existing as well as emerging imaging technologies for use in the elucidation of membrane microdomains will be highlighted. The organization of membrane microdomains in terms of dimensions and spatial distribution is of considerable interest and will be addressed in this Symposium.

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