On the Economic Foundation of the Urban Network Paradigm: Spatial Integration, Functional Integration and Economic Complementarities within the Dutch Randstad

The current debate on polycentric urban development suggests that inter-firm relations are important for the creation and sustainment of urban networks. Conceptually, the degrees of spatial and functional integration and urban complementarities in economic network relations are hypothesised to be important. However, the theoretical economic rationale has not been convincingly tested. In this paper, we use data on inter-firm relations in the Dutch Randstad to test conditions for integration and the existence of economic complementarities within this region. Contrary to the ‘polycentricity hypothesis’, we observe a clear hierarchy in the different types of spatial interdependencies in the Randstad, in which the central place model prevails. Furthermore, we do not find evidence for the functional integration of municipalities in the Randstad. We conclude that at this moment the Randstad does not function as a spatially and functionally integrated region, and that spatial economic policy can better focus on smaller regions within the Randstad when urban economic complementarities and integration are desired. This also calls into question the applicability of the urban network concept in general, as the Dutch Randstad is usually seen as a prime example of an economically successful polycentric urban system

Agglomeration and New Establishment Survival: A Mixed Hierarchical and Cross-Classified Model

Recent empirical studies in regional science and urban economics show that agglomeration economies may be one source of the uneven distribution of economic activities and economic growth across cities and regions. At the same time, the body of research into the importance of agglomeration economies for the performance of firms is still growing. Such development is necessary, as the theories that underlie agglomeration economies are microeconomic in nature, but still insufficiently understood. In this study, we focus on the determinants of survival among new establishments in the advanced producer services sector in the Netherlands. Employing a mixed hierarchical and cross-classified probit regression, we introduce a model of establishment survival that is specific to characteristics of the internal and external environment of the establishment. Controlling for firm and sector characteristics, we conclude that location accounts for about 4% of the variance in the probability of survival of new establishments. We also find that localization and urbanization economies have a positive effect on the survival of new establishments. However, new establishments with large start-up sizes appear to profit more from agglomeration economies than new establishments with small start-up sizes

What is the market potential for on-demand services as a train station access mode?

Ride-hailing and other on-demand mobility services are often proposed as a solution for improving the accessibility of public transport by offering first/last mile connectivity. We study the potential of using on-demand services to improve train station access by means of a three-step sequential stated preference survey. We compare the preferences for on-demand services with the bicycle, car and public transport for accessing two alternative train stations at different access distances. We estimate a joint access mode and train station choice model. By estimating a latent class choice model, we uncover five distinct segments in the population. We describe the classes based on their stated preferences, travel behaviour, attitudes towards new mobility and their socio-demographic characteristics. The two largest classes, accounting for over half of the sample, are the most likely to adopt on-demand services. Having an average willingness-to-pay, they would choose these services for longer access distances, competing mainly with the car and local public transport. Applying the model estimates, we observe that while on-demand services mainly compete with public transportation (obtaining most of its travellers from it), they are not able to fully substitute a public transport service for train station access, as many users would switch to cycling or driving a car, rather than opting for the on-demand service

Potential of on-demand services for urban travel

On-demand mobility services are promising to revolutionise urban travel, but preliminary studies are showing that they may actually increase the total vehicle miles travelled, thereby worsening road congestion in cities. In this study, we assess the demand for on-demand mobility services in urban areas, using a stated preference survey, to understand the potential impact of introducing on-demand services on the current modal split. The survey was carried out in the Netherlands and offered respondents a choice between bike, car, public transport and on-demand services. 1,063 valid responses are analysed with a multinomial logit and a latent class choice model. By means of the latter, we uncover four distinctive groups of travellers based on the observed choice behaviour. The majority of the sample (55%) are avid cyclists and do not see on-demand mobility as an alternative for making urban trips. Two classes (27% and 9% of the sample) would potentially use on-demand services: the former is fairly time-sensitive and would thus use on-demand service if they were sufficiently fast. The latter class however is highly cost-sensitive, and would therefore use on-demand mobility primarily if it is cheap. The fourth class (9%) shows very limited potential for using on-demand services

Multilevel Approaches and the Firm-Agglomeration Ambiguity in Economic Growth Studies

Empirical studies in spatial economics have shown that agglomeration economies may be a source of the uneven distribution of economic activities and economic growth across cities and regions. Both localization and urbanization economies are hypothesized to foster agglomeration and growth, but recent meta-analyses of this burgeoning body of empirical research show that the results are ambiguous. Recent overviews show that this ambiguity is fuelled by measurement issues and heterogeneity in terms of scale of time and space, aggregation, growth definitions, and the functional form of the models applied. Alternatively, in this paper, we argue that ambiguity may be due to a lack of research on firm-level performance in agglomerations. This research is necessary because the theories that underlie agglomeration economies are microeconomic in nature. Hierarchical or multilevel modeling, which allows micro levels and macro levels to be modeled simultaneously, is becoming an increasingly common practice in the social sciences. As illustrated by detailed Dutch data on firm-level productivity, employment growth and firm survival, we argue that these approaches are also suitable for reducing the ambiguity surrounding the agglomeration-firm performance relationship and for addressing spatial, sectoral and cross-level heterogeneity

SDSS Observations of Kuiper Belt Objects: Colors and Variability

Colors of Trans Neptunian Objects (TNOs) are used to study the evolutionary processes of bodies in the outskirts of the Solar System, and to test theories regarding their origin. Here I describe a search for serendipitous Sloan Digital Sky Survey (SDSS) observations of known TNOs and Centaurs. I present a catalog of SDSS photometry, colors and astrometry of 388 measurements of 42 outer Solar-System objects. I find a weak evidence, at the ~2-sigma level (per trial), for a correlation between the g-r color and inclination of scattered disk objects and hot classical KBOs. I find a correlation between the g-r color and the angular momentum in the z direction of all the objects in this sample. Light curves as a function of phase angle are constructed for 13 objects. The steepness of the slopes of these light curves suggests that the coherent backscatter mechanism plays a major role in the reflectivity of outer Solar-System small objects at small phase angles. I find a weak evidence for an anti-correlation, significant at the 2-sigma confidence level (per trial), between the g-band phase angle slope parameter and the semi-major axis, as well as the aphelion distance, of these objects. I discuss the origin of this possible correlation and argue that if this correlation is real it probably indicates that "Sedna"-like objects have a different origin than other classes of TNOs. Finally, I identify several objects with large variability amplitudes (abridged).Comment: 8 pages, ApJ in pres

Gravity with extra dimensions and dark matter interpretation: Phenomenological example via Miyamoto-Nagai galaxy

A configuration whose density profile coincides with the Newtonian potential for spiral galaxies is constructed from a 4D isotropic metric plus extra dimensional components. A Miyamoto-Nagai ansatz is used to solve Einstein equations. The stable rotation curves of such system are computed and, without fitting techniques, we recover with accuracy the observational data for flat or not asymptotically flat galaxy rotation curves. The density profiles are reconstructed and compared to that obtained from the Newtonian potential.Comment: 10 pages, 10 figures, submitted to Brazilian Journal of Physic

Hierarchical clustering and formation of power-law correlation in 1-dimensional self-gravitating system

The process of formation of fractal structure in one-dimensional self-gravitating system is examined numerically. It is clarified that structures created in small spatial scale grow up to larger scale through clustering of clusters, and form power-law correlation.Comment: 9pages,4figure

Errors in kinematic distances and our image of the Milky Way Galaxy

Errors in the kinematic distances, under the assumption of circular gas orbits, were estimated by performing synthetic observations of a model disk galaxy. It was found that the error is < 0.5 kpc for most of the disk when the measured rotation curve was used, but larger if the real rotation curve is applied. In both cases, the error is significantly larger at the positions of the spiral arms. The error structure is such that, when kinematic distances are used to develope a picture of the large scale density distribution, the most significant features of the numerical model are significantly distorted or absent, while spurious structure appears. By considering the full velocity field in the calculation of the kinematic distances, most of the original density structures can be recovered.Comment: Accepted for publication in A