The discrete dynamics of small-scale spatial events: agent-based models of mobility in carnivals and street parades

Small-scale spatial events are situations in which elements or objects vary in such away that temporal dynamics is intrinsic to their representation and explanation. Someof the clearest examples involve local movement from conventional traffic modelingto disaster evacuation where congestion, crowding, panic, and related safety issue arekey features of such events. We propose that such events can be simulated using newvariants of pedestrian model, which embody ideas about how behavior emerges fromthe accumulated interactions between small-scale objects. We present a model inwhich the event space is first explored by agents using ?swarm intelligence?. Armedwith information about the space, agents then move in an unobstructed fashion to theevent. Congestion and problems over safety are then resolved through introducingcontrols in an iterative fashion and rerunning the model until a ?safe solution? isreached. The model has been developed to simulate the effect of changing the route ofthe Notting Hill Carnival, an annual event held in west central London over 2 days inAugust each year. One of the key issues in using such simulation is how the processof modeling interacts with those who manage and control the event. As such, thischanges the nature of the modeling problem from one where control and optimizationis external to the model to one where this is intrinsic to the simulation

Traffic, urban growth and suburban sprawl

Cities are still getting bigger in the western world. Even though urbanpopulations are barely reproducing themselves and migration from thecountryside to the town has slowed to a trickle, the demand for more livingspace shows no sign of abating as cities continue to expand their bordersthrough suburban sprawl. The automobile, of course, makes this possiblebut we show no signs of moving to other forms of transport that mightenable our cities to become a little more compact. The problems of sprawlare pervasive. Besides congestion, time wasted, and the long term costs ofusing non-renewable energy, the lack of good social infrastructure inrapidly growing suburban areas together with the erosion of agriculturalland, often of high environmental quality, has focused the debate onwhether or not such forms of development are sustainable. In this paper,we begin by noting that suburban sprawl is an age-old phenomenon whichrepresents a fine balance between the forces that are pushing peopletogether in cities and those that are forcing them out. These lead todifferent types of sprawl in different places and at different times butwhatever the variety, there are costs to be borne. We briefly review these,noting how these affect suburban sprawl in Europe, and the efforts of theEuropean Commission to understand the problem. We conclude not with aplea that cities should be compacted and all automobile traffic removedbut that we should engage in policies for ?smart growth? such as thosebeing adopted in North America

Macro and Micro Dynamics of City Size Distributions: The Case of Israel

We study the distribution of sizes in the Israeli system of cities, using a rank-size representation of population distributions from 1950 to 2005. Based on a multiplicative model of proportionate growth, we develop a quantitative comparison relating the change in the rank-size curves to the change in the real data of Israeli cities during this period. At the level of macro dynamics, there is good agreement between the model and the real data. At the micro level, however, the model is less successful as the mean variation of the cities’ rank during the period studied is much larger in the model than in the real data. To illustrate this difference, we use the rankclock representation

Representing multifunctional cities: density and diversity in space and time

In this paper, we define measures of urban diversity, density and segregation using newdata and software systems based on GIS. These allow us to visualise the meaning of themultifunctional city. We begin with a discussion of how cities have become moresegregated in their land uses and activities during the last 200 years and how the currentfocus is on reversing this trend through limiting urban sprawl and bringing new lifeback to the inner and central city. We define various indices which show how diversityand density manifest themselves spatially. We argue that multifunctionalism is a relativeconcept, dependent upon the spatial and temporal scale that we use to think about themixing and concentration of urban land uses. We present three examples using spatiallysmoothed indicators of diversity: for a world city ? London, for a highly controlledpolycentric urban region ? Randstad Holland, and for a much more diffusely populatedsemi-urban region ? Venice-Padua-Teviso. We conclude by illustrating that urbandiversity varies as people engage in different activities associated with different landuses throughout the day, as well as through the vertical, third dimension of the city. Thisimpresses the point that we need to understand multifunctional cities in all theirdimensions of space and time

The Network Analysis of Urban Streets: A Primal Approach

The network metaphor in the analysis of urban and territorial cases has a long tradition especially in transportation/land-use planning and economic geography. More recently, urban design has brought its contribution by means of the "space syntax" methodology. All these approaches, though under different terms like accessibility, proximity, integration,connectivity, cost or effort, focus on the idea that some places (or streets) are more important than others because they are more central. The study of centrality in complex systems,however, originated in other scientific areas, namely in structural sociology, well before its use in urban studies; moreover, as a structural property of the system, centrality has never been extensively investigated metrically in geographic networks as it has been topologically in a wide range of other relational networks like social, biological or technological. After two previous works on some structural properties of the dual and primal graph representations of urban street networks (Porta et al. cond-mat/0411241; Crucitti et al. physics/0504163), in this paper we provide an in-depth investigation of centrality in the primal approach as compared to the dual one, with a special focus on potentials for urban design.Comment: 19 page, 4 figures. Paper related to the paper "The Network Analysis of Urban Streets: A Dual Approach" cond-mat/041124

Airbnb and its potential impact on the London housing market

This article identifies proxies which account for the impacts that the Airbnb platform is having on housing in Greater London. We identify these by analysing the relationships between possible Airbnb misuse and the attributes of housing in the same locations. We assume misuse when listings of entire properties within the Airbnb platform do not conform with local regulations and where hosts who offer such housing have multiple listings. In particular, we examine (1) the dwelling type based on building typology; (2) the type of housing tenure, whether it is owned or rented; and (3) the spatial distribution of changes in rent payable. Three important findings emerge from our analysis. First, based on 2018 data, we estimate that more than 2% of all properties in London, and up to 7% in some local areas are being misused through Airbnb as short-term holiday rentals. Second, the location of these particular Airbnb rentals is negatively correlated with the diversity of dwelling types and positively correlated with dwelling type such as an apartment (or flat) in areas of high private rental stock. Last, we show that a 100% increase in the density of possible Airbnb misuse can be associated with up to an 8% increase in unit rental price per-bedroom per-week, an equivalent to up to an average of £90 price increase per year. Finally, we discuss how this type of analysis can help build instruments to inform policies associated with the platform economy in relation to increasing polarisation in the London housing market

Diverse cities or the systematic paradox of Urban Scaling Laws

Scaling laws are powerful summaries of the variations of urban attributes with city size. However, the validity of their universal meaning for cities is hampered by the observation that different scaling regimes can be encountered for the same territory, time and attribute, depending on the criteria used to delineate cities. The aim of this paper is to present new insights concerning this variation, coupled with a sensitivity analysis of urban scaling in France, for several socio-economic and infrastructural attributes from data collected exhaustively at the local level. The sensitivity analysis considers different aggregations of local units for which data are given by the Population Census. We produce a large variety of definitions of cities (approximatively 5000) by aggregating local Census units corresponding to the systematic combination of three definitional criteria: density, commuting flows and population cutoffs. We then measure the magnitude of scaling estimations and their sensitivity to city definitions for several urban indicators, showing for example that simple population cutoffs impact dramatically on the results obtained for a given system and attribute. Variations are interpreted with respect to the meaning of the attributes (socio-economic descriptors as well as infrastructure) and the urban definitions used (understood as the combination of the three criteria). Because of the Modifiable Areal Unit Problem (MAUP) and of the heterogeneous morphologies and social landscapes in the cities' internal space, scaling estimations are subject to large variations, distorting many of the conclusions on which generative models are based. We conclude that examining scaling variations might be an opportunity to understand better the inner composition of cities with regard to their size, i.e. to link the scales of the city-system with the system of cities

Antiproton-deuteron annihilation at low energies

Recent experimental studies of the antiproton-deuteron system at low energies have shown that the imaginary part of the antiproton-deuteron scattering length is smaller than the antiproton-proton one. Two- and three-body systems with strong annihilation are investigated and a mechanism explaining this unexpected relation between the imaginary parts of the scattering lengths is proposed.Comment: 6 pages, 3 figures, to be published in The European Physical Journal

Estimated cardiorespiratory fitness in childhood and cardiometabolic health in adulthood: 1970 British Cohort Study

BACKGROUND Associations of cardiorespiratory fitness in childhood and adulthood with adult cardiometabolic risk factors are poorly understood, not least because of the paucity of studies. OBJECTIVES We investigated associations between nonexercise testing cardiorespiratory fitness (NETCRF) in childhood/adulthood and cardiometabolic risk factors in adulthood. METHODS Based on an established algorithm comprising gender, age, body mass index, resting heart rate, and self‐reported physical activity at age 10, we computed NETCRF. Risk factors were assessed at age 46 in 5,009 participants when NETCRF was again calculated. Linear regression was used to summarise associations between NETCRF in childhood and risk factors in adulthood and, additionally, the relationship between NETCRF in adulthood and risk factors in adulthood after adjusting for childhood NETCRF. RESULTS Inconsistent associations were observed between childhood NETCRF and adult risk factors. NETCRF in adulthood was associated with blood pressure [‐5.8 (‐6.7, ‐4.9)], glycated haemoglobin [‐3.41 (‐4.06, ‐2.76)], total cholesterol [‐0.16 (‐0.24, ‐0.08)], HDL‐cholesterol [0.19 (0.16, 0.22)], triglycerides [‐0.68 (‐0.85, ‐0.50)] and C‐reactive protein [‐0.29 (‐0.35, ‐0.22)] in adult males. Similar associations were observed in adult females. Compared to those with low estimated fitness in both childhood and adulthood, participants with low fitness in childhood and high fitness in adulthood had a lower risk of two or more cardiometabolic risk factors (odds ratio: 0.22; 95% confidence interval: 0.16, 0.30). CONCLUSION Associations between estimated fitness and risk factors are stronger in adulthood than from childhood to adulthood. Adults with previously sedentary childhoods may still gain benefits from improving their fitness

A land-use transport-interaction framework for large scale strategic urban modeling

We introduce a family of land use transportation interaction (LUTI) models which enable future employment, population and flows or trips between these activities to be explained and predicted. We begin by focusing on the generic spatial interaction model, noting the ways in which its components reflect demand and supply at different locations measured in terms of employment and working population. This suggests an equilibrium structure which is our starting point in developing a simplified version of the model which we extend to deal with four different activity sectors – housing, retail activities, schools, and health facilities. We use this generic structure to develop four related versions of the generic LUTI model equations for residential populations, retailing, education and hospitals which are all driven by employment in terms of where people live and work. This constitutes our integrated framework that we use in calibrating, that is fine-tuning the model to three urban areas (cities) in Europe: to Oxford and its county, Turin and its region, and Athens in its hinterland of Attica reflecting population volumes from 700,000, 1.7 million and 3.8 million persons respectively. In each case, we use the models to predict the impact of different scenarios – new housing developments in Oxfordshire, new universities and metro lines in Turin, and economic development in the Athens region. We describe the details of these scenarios in Supplementary Information (SI) which shows the versatility of using the models to examine such impacts and we conclude with directions for improving the various models and nesting them at different scales within the land use-transport planning process