scholarly journals Are Cities Truly Dispersed? A Long-Term Analysis of Vertical Profile of Settlements in Athens’ Metropolitan Region

2021 ◽  
Vol 13 (6) ◽  
pp. 3365
Author(s):  
Jesús Rodrigo-Comino ◽  
Barbara Ermini
Keyword(s):  
Urban Form ◽  
Vertical Profile ◽  
Urban Expansion ◽  
Metropolitan Region ◽  
Time Interval ◽  
Spatial Direction ◽  
Socioeconomic Changes ◽  
Long Time ◽  
Nonparametric Correlation ◽  
Over Time

Using nonparametric, exploratory statistics, the spatial structure of the city’s vertical profile was investigated at the municipal scale in Athens’ metropolitan region (Greece), evaluating changes over a sufficiently long time interval (1983–2019) that encompasses different phases of the urban cycle in Greece. Assuming the vertical profile of cities as an honest indicator of urban form, the study was aimed to test the intensity and spatial direction of the (supposed) change in settlement models toward sprawl. Transitioning slowly from a dense to a more dispersed settlement structure, Athens’ dynamics revealed a quite representative model for cities expanding significantly but remaining substantially compact and dense, while responding similarly to different (external) economic stimuli. Nonparametric correlation between the average (vertical) profile of each municipality and the distance from downtown Athens revealed a substantially stable mono-centric structure over time, with small changes over time still responding to factors dependent on the urban gradient. The inherent shift towards “horizontal” urban expansion was relatively modest and characteristic of few periurban contexts. The empirical results of this study can be envisaged as a practical tool of regional planning, allowing continuous monitoring of urban sprawl and land take in complex systems under rapid socioeconomic changes.

scholarly journals Rural in Town: Traditional Agriculture, Population Trends, and Long-Term Urban Expansion in Metropolitan Rome

Land ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 53 ◽  
Author(s):  
Gianluca Egidi ◽  
Rares Halbac-Cotoara-Zamfir ◽  
Sirio Cividino ◽  
Giovanni Quaranta ◽  
Luca Salvati ◽  
...  
Keyword(s):  
Urban Agriculture ◽  
Urban Growth ◽  
Urban Expansion ◽  
Population Trends ◽  
Metropolitan Region ◽  
Economic Activities ◽  
Metropolitan Regions ◽  
Scale Population ◽  
Mediterranean Regions ◽  
Long Time

Mediterranean regions have experienced a shift from accelerated urban growth typical of a post-industrial phase to a more recent spatial delocalization of population and economic activities reflecting discontinuous settlement expansion, land take, and the abandonment of cultivated areas around central cities. On the basis of a comprehensive analysis of land-use, settlement, and demographic indicators, the present study explores urban growth and population density over a sufficiently long time period in a metropolitan region of Southern Europe (Rome, Italy). Local-scale population trends were compared with the evolution of the primary sector (workers in agriculture, number of farms, cultivated land) between 1951 and 2011. Our results indicate non-linear growth waves alternating compact and discontinuous expansion shaping fringe land. The future development of metropolitan regions is increasingly dependent on the relationship between urban diffusion and economic viability of peri-urban agriculture. Crop abandonment and land take rates increase in local contexts where peri-urban agriculture rapidly declines. Policies managing ex-urban development and promoting the recovery of fringe soils are increasingly required to contain the expansion of dispersed settlements and preserve relict agricultural systems from land conversion to urban use.

Urban Sprawl and the Quantification of Spatial Dispersion

2013 ◽  
pp. 129-142 ◽  
Author(s):  
Federico Martellozzo ◽  
Keith C. Clarke
Keyword(s):  
Urban Sprawl ◽  
Urban Growth ◽  
Urban Form ◽  
Spatial Dispersion ◽  
Temporal Dynamics ◽  
Urban Expansion ◽  
Natural Land ◽  
Spatio Temporal ◽  
Environment Agency ◽  
Over Time

The uncontrolled spread of cities into their surrounding rural and natural land is an issue of high popular interest and has been the topic of considerable research. Urban sprawl remains controversial, even though among scholars there are still no unambiguous definitions of sprawled zones--their spatial form and their causative factors--nor about the urban processes and dynamics involved. In order to create such a definition, the authors describe the spatio-temporal patterns of urban form in a study area noted for sprawl, focusing on measures that can detect the degree of urban spatial dispersion over time (Batty 2002). The data used is a fusion of archived thematic maps, classified satellite imagery, census data, and forecast maps of future urban scenarios. The area investigated was the northeastern province of Pordenone in Italy, which is particularly relevant and curious because despite being a small city, it was assessed in 2002 as one of the most explicative examples of sprawl in Europe by the European Environment Agency. The authors analyzed urban growth mainly through the evolution of urban patterns over time, hence sprawl is considered as a specific case of growth that drives urban expansion from denser and compact extent to an unorganized and fragmented pattern. How the spatio-temporal dynamics of urban growth are quantified is crucial for urban planners, as knowledge of amounts and rates allows more efficient selection and application of policy and could help researchers to better understand urban sprawl’s etiology.

scholarly journals Clustering or Scattering? The Spatial Distribution of Cropland in a Metropolitan Region, 1960–2010

2018 ◽  
Vol 10 (7) ◽  
pp. 2584 ◽  
Author(s):  
Andrea Colantoni ◽  
Ilaria Zambon ◽  
Maria Gras ◽  
Enrico Maria Mosconi ◽  
Alessandra Stefanoni ◽  
...  
Keyword(s):  
Land Use ◽  
Growth Rate ◽  
Population Growth ◽  
Population Growth Rate ◽  
Spatial Behavior ◽  
Metropolitan Region ◽  
Time Interval ◽  
Non Linear ◽  
Long Time ◽  
Agricultural Areas

This article presents empirical results of a multivariate analysis run with the aim to identify (apparent and latent) socioeconomic transformations that shape the distribution pattern of cropland in a metropolitan region of southern Europe (Athens, Greece) over a sufficiently long time interval spanning from 1960 to 2010. The study area is representative of monocentric cities expanding in an unregulated fashion and experiencing sequential cycles of economic growth and recession. Percent share of cropland in total municipal area increased moderately over time. A non-linear relationship with the distance from downtown Athens was also observed, indicating that the highest rates of cropland were observed at a distance ranging between 20 and 30 km from the inner city. A multivariate regression was run by decade at each municipality of the study area using 11 predictors with the aim to identify the factors most associated with cropland decline along urban fringes. Distance from downtown Athens, soil and climate quality, population growth rate, and competing land use were the most relevant factors correlated with cropland expansion (or decline) in the study area. Competing land use was particularly important for cropland decline in a first urbanization phase (1960–1980), while population growth rate—and hence an increased human pressure—was positively associated with agricultural areas in a subsequent phase (1990–2010). In these regards, per capita urban land had a non-linear spatial behavior, being correlated negatively with cropland in 1960 and 1970 and positively in 2010, possibly indicating a moderate change from a monocentric model towards a more dispersed metropolitan configuration impacting distribution of agricultural areas. Empirical findings of this study suggest that effective strategies supporting peri-urban agriculture require a comprehensive knowledge of the local socioeconomic context and relevant biophysical conditions—specifically focusing on the dominant soil and climate attributes.

An Adaptive and Learning System for Feedback-Controlled Evoked Response Studies

1981 ◽  
Vol 20 (03) ◽  
pp. 169-173
Author(s):  
J. Wagner ◽  
G. Pfurtscheixer
Keyword(s):  
Brain Activity ◽  
Evoked Response ◽  
Learning System ◽  
Time Interval ◽  
Electrical Brain Activity ◽  
Long Time ◽  
The Subject ◽  
Eeg Power ◽  
Stimulation System ◽  
Background Eeg

The shape, latency and amplitude of changes in electrical brain activity related to a stimulus (Evoked Potential) depend both on the stimulus parameters and on the background EEG at the time of stimulation. An adaptive, learnable stimulation system is introduced, whereby the subject is stimulated (e.g. with light), whenever the EEG power is subthreshold and minimal. Additionally, the system is conceived in such a way that a certain number of stimuli could be given within a particular time interval. Related to this time criterion, the threshold specific for each subject is calculated at the beginning of the experiment (preprocessing) and adapted to the EEG power during the processing mode because of long-time fluctuations and trends in the EEG. The process of adaptation is directed by a table which contains the necessary correction numbers for the threshold. Experiences of the stimulation system are reflected in an automatic correction of this table. Because the corrected and improved table is stored after each experiment and is used as the starting table for the next experiment, the system >learns<. The system introduced here can be used both for evoked response studies and for alpha-feedback experiments.

scholarly journals Optimal Perturbations of an Oceanic Vortex Lens

Fluids ◽  
2018 ◽  
Vol 3 (3) ◽  
pp. 63 ◽  
Author(s):  
Thomas Meunier ◽  
Claire Ménesguen ◽  
Xavier Carton ◽  
Sylvie Le Gentil ◽  
Richard Schopp
Keyword(s):  
Normal Mode ◽  
Growth Rates ◽  
Time Interval ◽  
Time Intervals ◽  
Horizontal Structure ◽  
Azimuthal Wave ◽  
Wave Numbers ◽  
Non Linear ◽  
Long Time ◽  
Short Time

The stability properties of a vortex lens are studied in the quasi geostrophic (QG) framework using the generalized stability theory. Optimal perturbations are obtained using a tangent linear QG model and its adjoint. Their fine-scale spatial structures are studied in details. Growth rates of optimal perturbations are shown to be extremely sensitive to the time interval of optimization: The most unstable perturbations are found for time intervals of about 3 days, while the growth rates continuously decrease towards the most unstable normal mode, which is reached after about 170 days. The horizontal structure of the optimal perturbations consists of an intense counter-shear spiralling. It is also extremely sensitive to time interval: for short time intervals, the optimal perturbations are made of a broad spectrum of high azimuthal wave numbers. As the time interval increases, only low azimuthal wave numbers are found. The vertical structures of optimal perturbations exhibit strong layering associated with high vertical wave numbers whatever the time interval. However, the latter parameter plays an important role in the width of the vertical spectrum of the perturbation: short time interval perturbations have a narrow vertical spectrum while long time interval perturbations show a broad range of vertical scales. Optimal perturbations were set as initial perturbations of the vortex lens in a fully non linear QG model. It appears that for short time intervals, the perturbations decay after an initial transient growth, while for longer time intervals, the optimal perturbation keeps on growing, quickly leading to a non-linear regime or exciting lower azimuthal modes, consistent with normal mode instability. Very long time intervals simply behave like the most unstable normal mode. The possible impact of optimal perturbations on layering is also discussed.

scholarly journals Significant increase in quantity and quality of knee arthroplasty related research in KSSTA over the past 15 years

2021 ◽  
Author(s):  
Stephanie Kirschbaum ◽  
Thilo Kakzhad ◽  
Fabian Granrath ◽  
Andrzej Jasina ◽  
Jakub Oronowicz ◽  
...  
Keyword(s):  
Knee Arthroplasty ◽  
Special Topic ◽  
Computer Assisted ◽  
Time Interval ◽  
Search Term ◽  
Level Of Evidence ◽  
The Past ◽  
Patient Reported ◽  
Over Time ◽  
Number Of Authors

Abstract Purpose This study aimed to evaluate both publication and authorship characteristics in Knee Surgery, Sports Traumatology, Arthroscopy journal (KSSTA) regarding knee arthroplasty over the past 15 years. Methods PubMed was searched for articles published in KSSTA between January 1, 2006, and December 31st, 2020, utilising the search term ‘knee arthroplasty’. 1288 articles met the inclusion criteria. The articles were evaluated using the following criteria: type of article, type of study, main topic and special topic, use of patient-reported outcome scores, number of references and citations, level of evidence (LOE), number of authors, gender of the first author and continent of origin. Three time intervals were compared: 2006–2010, 2011–2015 and 2016–2020. Results Between 2016 and 2020, publications peaked at 670 articles (52%) compared with 465 (36%) published between 2011 and 2016 and 153 articles (12%) between 2006 and 2010. While percentage of reviews (2006–2010: 0% vs. 2011–2015: 5% vs. 2016–2020: 5%) and meta-analyses (1% vs. 6% vs. 5%) increased, fewer case reports were published (13% vs. 3% vs. 1%) (p < 0.001). Interest in navigation and computer-assisted surgery decreased, whereas interest in perioperative management, robotic and individualized surgery increased over time (p < 0.001). There was an increasing number of references [26 (2–73) vs. 30 (2–158) vs. 31 (1–143), p < 0.001] while number of citations decreased [30 (0–188) vs. 22 (0–264) vs. 6 (0–106), p < 0.001]. LOE showed no significant changes (p = 0.439). The number of authors increased between each time interval (p < 0.001), while the percentage of female authors was comparable between first and last interval (p = 0.252). Europe published significantly fewer articles over time (56% vs. 47% vs. 52%), whereas the number of articles from Asia increased (35% vs. 45% vs. 37%, p = 0.005). Conclusion Increasing interest in the field of knee arthroplasty-related surgery arose within the last 15 years in KSSTA. The investigated topics showed a significant trend towards the latest techniques at each time interval. With rising number of authors, the part of female first authors also increased—but not significantly. Furthermore, publishing characteristics showed an increasing number of publications from Asia and a slightly decreasing number in Europe. Level of evidence IV.

scholarly journals Assessing the Impact of Urban Expansion on Surrounding Forested Landscape Connectivity across Space and Time

Land ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 359
Author(s):  
Zhouqiao Ren ◽  
Jianhua He ◽  
Qiaobing Yue
Keyword(s):  
Landscape Connectivity ◽  
Urban Expansion ◽  
Landscape Fragmentation ◽  
Sustainable Urban Development ◽  
Delayed Response ◽  
Conservation Practices ◽  
Rapid Urbanization ◽  
Dynamic Landscapes ◽  
The Impact ◽  
Over Time

Landscape connectivity is important for all organisms as it directly affects population dynamics. Yet, rapid urbanization has caused serious landscape fragmentation, which is the primary contributor of species extinctions worldwide. Previous studies have mostly used spatial snap-shots to evaluate the impact of urban expansion on landscape connectivity. However, the interactions among habitats over time in dynamic landscapes have been largely ignored. Here, we demonstrated that overlooking temporal connectivity can lead to the overestimation of the impact of urban expansion. How much greater the overestimation is depends on the amount of net habitat loss. Moreover, we showed that landscape connectivity may have a delayed response to urban expansion. Our analysis shifts the way to understand the ecological consequences of urban expansion. Our framework can guide sustainable urban development and can be inspiring to conservation practices under other contexts (e.g., climate change).

scholarly journals Dynamics of life expectancy and life span equality

2020 ◽  
Vol 117 (10) ◽  
pp. 5250-5259 ◽  
Author(s):  
José Manuel Aburto ◽  
Francisco Villavicencio ◽  
Ugofilippo Basellini ◽  
Søren Kjærgaard ◽  
James W. Vaupel
Keyword(s):  
Life Expectancy ◽  
Life Span ◽  
Health Policies ◽  
Public Health Policies ◽  
Dynamic Relationship ◽  
Mortality Increase ◽  
Long Time ◽  
Underlying Causes ◽  
The Relationship ◽  
Over Time

As people live longer, ages at death are becoming more similar. This dual advance over the last two centuries, a central aim of public health policies, is a major achievement of modern civilization. Some recent exceptions to the joint rise of life expectancy and life span equality, however, make it difficult to determine the underlying causes of this relationship. Here, we develop a unifying framework to study life expectancy and life span equality over time, relying on concepts about the pace and shape of aging. We study the dynamic relationship between life expectancy and life span equality with reliable data from the Human Mortality Database for 49 countries and regions with emphasis on the long time series from Sweden. Our results demonstrate that both changes in life expectancy and life span equality are weighted totals of rates of progress in reducing mortality. This finding holds for three different measures of the variability of life spans. The weights evolve over time and indicate the ages at which reductions in mortality increase life expectancy and life span equality: the more progress at the youngest ages, the tighter the relationship. The link between life expectancy and life span equality is especially strong when life expectancy is less than 70 y. In recent decades, life expectancy and life span equality have occasionally moved in opposite directions due to larger improvements in mortality at older ages or a slowdown in declines in midlife mortality. Saving lives at ages below life expectancy is the key to increasing both life expectancy and life span equality.

scholarly journals Radiomorphology of the Habib Sealer-Induced Resection Plane during Long-Time Followup:A Longitudinal Single Center Experience after 64 Radiofrequency-AssistedLiver Resections

HPB Surgery ◽  
2010 ◽  
Vol 2010 ◽  
pp. 1-7 ◽  
Author(s):  
Robert Kleinert ◽  
Roger Wahba ◽  
Christoph Bangard ◽  
Klaus Prenzel ◽  
Arnulf H. Hölscher ◽  
...  
Keyword(s):  
Liver Resection ◽  
Morphological Characteristics ◽  
Postoperative Mortality ◽  
Coagulation Necrosis ◽  
Time Interval ◽  
Safe Alternative ◽  
Time Points ◽  
Single Center Experience ◽  
Long Time

Background. Radiofrequency (RF-) assisted liver resection devices like the Habib sealer induce a necrotic resection plane from which a small margin of necrotic liver tissue remains in situ. The aim of the present paper was to report our long-time experience with the new resection method and the morphological characteristics of the remaining necrotic resection plane. Methods. 64 RF-assisted liver resections were performed using the Habib sealer. Followup was assessed at defined time points. Results. The postoperative mortality was 3,6% and morbidity was 18%. The followup revealed that the necrotic zone was detectable in all analyzed CT and MRI images as a hypodense structure without any contrast enhancement at all time points, irrespectively of the time interval between resection and examination. Conclusion. Liver resection utilizing radiofrequency-induced resection plane coagulation is a safe alternative to the established resection techniques. The residual zone of coagulation necrosis remains basically unchanged during a followup of three years. This has to be kept in mind when evaluating the follow up imaging of these patients.

LONG‐TIME RESPONSE PREDICTED BY EXACT ELASTIC RAY THEORY

Geophysics ◽  
1965 ◽  
Vol 30 (3) ◽  
pp. 363-368 ◽  
Author(s):  
T. W. Spencer
Keyword(s):  
Formal Solution ◽  
Intermediate Stage ◽  
Time Limit ◽  
Time Interval ◽  
Individual Response ◽  
Axially Symmetric ◽  
Long Time ◽  
The Difference ◽  
The Individual ◽  
Significant Figures

The formal solution for an axially symmetric radiation field in a multilayered, elastic system can be expanded in an infinite series. Each term in the series is associated with a particular raypath. It is shown that in the long‐time limit the individual response functions produced by a step input in particle velocity are given by polynomials in odd powers of the time. For rays which suffer m reflections, the degree of the polynomials is 2m+1. The total response is obtained by summing all rays which contribute in a specified time interval. When the rays are selected indiscriminately, the difference between the magnitude of the partial sum at an intermediate stage of computation and the magnitude of the correct total sum may be greater than the number of significant figures carried by the computer. A prescription is stated for arranging the rays into groups. Each group response function varies linearly in the long‐time limit and goes to zero when convolved with a physically realizable source function.

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