More People, More Jobs: Urban Renaissance in Germany

Germany's big cities are gaining in attractiveness both as a place for living and as a location for companies. Even as Germany's total population is declining, the population of cities increased by nearly 3 percent between 1999 and 2008. The same is true for spatial shifts in the economy: During the past 10 years employment in big cities increased by nearly 4 percent while stagnating in Germany as a whole. Demographic and economic trends towards cities influence each other. On the one hand young skilled people are accepting job offers in the cities. On the other hand companies are now taking the preferences of highly skilled employees into account when choosing a location because know-how is scarce. The big cities' new attractiveness is especially appealing to young people with an above-average income. Their main problem is to reconcile their career desires with their wish for a family. Cities are more able to profit from the new trend in people's choice of residence if they create better conditions for children. At the same time, good urban planning can help mitigate the social conflicts and expulsion effects that result from gentrification in the city centers.Knowledge-intensive services, Urban renaissance, Population growth

Resolving Gas Flows in the Ultraluminous Starburst IRAS23365+3604 with Keck LGSAO/OSIRIS

Keck OSIRIS/LGSAO observations of the ultraluminous galaxy IRAS~23365+3604 resolve a circumnuclear bar (or irregular disk) of semimajor axis 0.42" (520 pc) in Paschen-alpha emission. The line-of-sight velocity of the ionized gas increases from the northeast toward the southwest; this gradient is perpendicular to the photometric major axis of the infrared emission. Two pairs of bends in the zero-velocity line are detected. The inner bend provides evidence for gas inflow onto the circumnuclear disk/bar structure. We interpret the gas kinematics on kiloparsec scales in relation to the molecular gas disk and multiphase outflow discovered previously. In particular, the fast component of the outflow (detected previously in line wings) is not detected, adding support to the conjecture that the fast wind originates well beyond the nucleus. These data directly show the dynamics of gas inflow and outflow in the central kiloparsec of a late-stage, gas-rich merger and demonstrate the potential of integral field spectroscopy to improve our understanding of the role of gas flows during the growth phase of bulges and supermassive black holes.Comment: 14 pages with 7 figures accepted to the astrophysical journa

Towards finite-dimensional gelation

We consider the gelation of particles which are permanently connected by random crosslinks, drawn from an ensemble of finite-dimensional continuum percolation. To average over the randomness, we apply the replica trick, and interpret the replicated and crosslink-averaged model as an effective molecular fluid. A Mayer-cluster expansion for moments of the local static density fluctuations is set up. The simplest non-trivial contribution to this series leads back to mean-field theory. The central quantity of mean-field theory is the distribution of localization lengths, which we compute for all connectivities. The highly crosslinked gel is characterized by a one-to-one correspondence of connectivity and localization length. Taking into account higher contributions in the Mayer-cluster expansion, systematic corrections to mean-field can be included. The sol-gel transition shifts to a higher number of crosslinks per particle, as more compact structures are favored. The critical behavior of the model remains unchanged as long as finite truncations of the cluster expansion are considered. To complete the picture, we also discuss various geometrical properties of the crosslink network, e.g. connectivity correlations, and relate the studied crosslink ensemble to a wider class of ensembles, including the Deam-Edwards distribution.Comment: 18 pages, 4 figures, version to be published in EPJ

Creating effective focus cues in multi-plane 3D displays.

Focus cues are incorrect in conventional stereoscopic displays. This causes a dissociation of vergence and accommodation, which leads to visual fatigue and perceptual distortions. Multi-plane displays can minimize these problems by creating nearly correct focus cues. But to create the appearance of continuous depth in a multi-plane display, one needs to use depth-weighted blending: i.e., distribute light intensity between adjacent planes. Akeley et al. [ACM Trans. Graph. 23, 804 (2004)] and Liu and Hua [Opt. Express 18, 11562 (2009)] described rather different rules for depth-weighted blending. We examined the effectiveness of those and other rules using a model of a typical human eye and biologically plausible metrics for image quality. We find that the linear blending rule proposed by Akeley and colleagues [ACM Trans. Graph. 23, 804 (2004)] is the best solution for natural stimuli

Economic Growth of Agglomerations and Geographic Concentration of Industries: Evidence for Germany

The vast majority of regions in West Germany, and the EU, have become more similar in terms of per-capita income and productivity between 1980 and 2000. But a number of rich areas - generally large agglomerations - have succeeded in departing from this trend of convergence. They are continuing to rise above the average productivity level. We examine whether this development can also be seen as due to changes in the spatial distribution of economic sectors. Knowledge-intensive services in particular are identified as industries that combine employment growth and further geographical concentration. Logistical and non-parametric regressions confirm a positive relation between the regional weight of sectors that are continuing to concentrate geographically and the probability that this region will develop ahead of the general trend. We find that increasing localisation of fast growing industries is an important factor behind the changes in the spatial pattern of the economy.

Productivity Differences in the European Union: National, Regional and Spatial Effects

Using panel data on European regions and applying Analysis of Covariance, our study provides an empirical assessment of the relative importance of national, regional and spatial factors for explaining variations of productivity. Our analysis shows that initial economic conditions or agglomeration and centrality are indeed relevant for differences in productivity levels. What is far more important, however, is which country a region belongs to. Productivity differences in the European Union are thus obviously dominated by national regimes. In light of the historically strong influence of the nation states, this result may come as no surprise. What is surprising is the fact that the role of countries has not decreased over time, despite intensive integration efforts (European Single Market, Economic and Monetary Union).Regional productivity, agglomeration and centrality, panel data econometrics

Multistep Predictions for Multivariate GARCH Models: Closed Form Solution and the Value for Portfolio Management

The missing wage rigidity in general equilibrium models of efficiency wages is an artifact of the external wage reference perspective conventionally adopted by the literature. Efficiency wage models based on an internal wage reference perspective are capable of generating strong wage rigidity. We propose a structural model of efficiency wages that is broadly consistent with the reported evidence on fairness in labor relations and rent-sharing. Our model provides a robust explanation for wage rigidity and procyclical effort. It also rationalizes reciprocal behavior by workers and the observation that firm productivity is a significant predictor of wage setting.multivariate GARCH models; volatility forecasts; portfolio optimization; minimum variance portfolio

Regional productivity differences in the European Union - Theoretical predictions and empirical evidence

The analysis of regional income and productivity differences in the European Union (EU) has some tradition. The theoretical framework of most empirical studies on these subjects is the neoclassical growth model. Thus, research has focussed on convergence of income and productivity among EU regions. While spatial clustering is an issue in a number of studies, geography is rarely taken into account. This paper takes an explicitly spatial perspective, so we are able to look at an alternative theoretical approach, the New Economic Geography (NEG). Our regional classification is a modified version of the NUTS2 level. We use the degree of agglomeration and the geographical location (core vs. periphery) as geographical indicators. This allows for the empirical evaluation of some of the ideas of NEG regarding the pattern and development of regional productivity differences of EU regions. The analysis covers the period from 1982 to 2000. We develop a two-stage estimation strategy. Using panel data analysis in the first stage we estimate region-specific effects on productivity and its dynamics in terms of production and employment growth. In the second stage we apply Analysis of Covariance in order to explain those region-specific effects through other time-invariant factors and to estimate the impact of these factors on productivity. Our results indicate a strong significance of region-specific factors for productivity differences in the EU. The geographical indicators are significant but their impact appears to be rather limited. While the estimated parameters of the categorial spatial variables are consistent with predictions of the NEG, unobserved heterogenity at the national level is much more important. State-specific effects can explain a major part of variation in regional productivity. This implies that the regional pattern of productivity in the EU still is largely determined by national "productivity regimes". Regarding the productivity dynamics in the EU, we find a tendency towards convergence. This is in line with most other empirical studies on this subject. However the decrease of regional productivity differences is the result of two opposite processes: There is convergence of production but divergence of employment. Again national factors appear to dominate. We find that the dynamics of regional development in terms of output and employment growth are strongly determined by state-specific effects and these effects are varying significantly over time. A tentative interpretation of our results is that the economic development of regions within the EU can not be easily explained by either neoclassical theory or NEG. The reduction in regional productivity differences appears to be formed to a large extent by factors at the national level. Examples are the downsizing of low productivity agriculture in southern european countries or the boost in part-time employment in the Netherlands during the eighties. Further empirical research will have to establish whether the national component in regional development is attenuating and a European pattern of productivty growth is emerging.

Economic Growth of Agglomerations and Geographic Concentration of Industries – Evidence for Germany

The vast majority of regions in West Germany, and the EU, have become more similar in terms of per-capita income and productivity between 1980 and 2000. But a number of rich areas - generally large agglomerations - have succeeded in departing from this trend of convergence. They are continuing to rise above the average productivity level. We examine whether this development can also be seen as due to changes in the spatial distribution of economic sectors. Knowledge-intensive services in particular are identified as industries that combine employment growth and further geographical concentration. Logistical and nonparametric regressions confirm a positive relation between the regional weight of sectors that are continuing to concentrate geographically and the probability that this region will develop ahead of the general trend. We find that increasing localisation of fast growing industries is an important factor behind the changes in the spatial pattern of the economy.regional convergence, knowledge-intensive services, industry-specific local linkages, logistical regressions, non-parametric regressions