Local Employment Growth in West Germany - A Dynamic Panel Approach

In times of high and persistent unemployment, it has become one of the most important policy tasks in many developed countries to trigger a process of sustained employment growth. An illustrative example is the policy of regional “growth-poles”, which assumes that a local concentration of a specific industry in a limited geographical area will lead to a growth take-off. The theoretical rationale for this type of regional policy can be knowledge spillovers, whose importance for the economic (employment) growth has been emphasised in the endogenous growth literature. Yet, there is a considerable debate about the precise nature of knowledge spillovers. Do the externalities accrue between sectors (Jacobs-externalities), or are they rather intra-sectoral (MAR-externalities)? Apart from the question what local economic structure is conducive for employment growth, an equally important issue concerns the timing of the impact of externalities. Is it the current economic structure that matters for employment growth, or rather the historical economic structure? If the former turns out to be the case, regional policies might become effective immediately. In the latter case the impact of policy might be slower but also longer lasting. In this paper we study the dynamics of local employment growth in West Germany from 1980 to 2001. Using dynamic panel techniques, we analyse the nature and the timing of Jacobs- and Marshall-Arrow-Romer externalities, as well as the impact of general human capital spillovers. Jacobs-externalities are stronger in manufacturing than in services, the opposite is true for MAR-externalities. General human capital spillovers are only found in manufacturing. The influence of all forms of externalities rapidly decays in time, suggesting that they are rather static than dynamic. Additionally, we look at the impact of competition, general agglomeration effects and overly high regional wages on local employment growth.

Cultural Diversity and Local Labour Markets

During the last decade there have been marked changes in the composition of the non-native workforce in the German labour market. In particular there has been a notable increase in the diversity of nationalities of which the foreign workforce is composed. In this paper we investigate the effects of this diversity for native employees. Our analysis is conducted at the local level and uses a panel of 326 Western German regions over the time period 1995-2006. When considering high-skilled foreign workers, we find that both the size of this group and the diversification into different nationalities raise local wages and employment for native employees. For low-skilled foreign workers we find negative size effects. However, these negative effects can be partly offset if the group of low-skilled foreigners is culturally diversified. Our results imply that diversity raises productivity at the local level, but that it is important to distinguish the skill composition of the foreign workforce. These findings remain robust in a variety of robustness checks that take into account omitted variable bias, self-selection of foreigners into particular regions, and spatial autocorrelation.regional labour markets, cultural diversity, immigration, spatial equilibrium

The Complexity of Relating Quantum Channels to Master Equations

Completely positive, trace preserving (CPT) maps and Lindblad master equations are both widely used to describe the dynamics of open quantum systems. The connection between these two descriptions is a classic topic in mathematical physics. One direction was solved by the now famous result due to Lindblad, Kossakowski Gorini and Sudarshan, who gave a complete characterisation of the master equations that generate completely positive semi-groups. However, the other direction has remained open: given a CPT map, is there a Lindblad master equation that generates it (and if so, can we find it's form)? This is sometimes known as the Markovianity problem. Physically, it is asking how one can deduce underlying physical processes from experimental observations. We give a complexity theoretic answer to this problem: it is NP-hard. We also give an explicit algorithm that reduces the problem to integer semi-definite programming, a well-known NP problem. Together, these results imply that resolving the question of which CPT maps can be generated by master equations is tantamount to solving P=NP: any efficiently computable criterion for Markovianity would imply P=NP; whereas a proof that P=NP would imply that our algorithm already gives an efficiently computable criterion. Thus, unless P does equal NP, there cannot exist any simple criterion for determining when a CPT map has a master equation description. However, we also show that if the system dimension is fixed (relevant for current quantum process tomography experiments), then our algorithm scales efficiently in the required precision, allowing an underlying Lindblad master equation to be determined efficiently from even a single snapshot in this case. Our work also leads to similar complexity-theoretic answers to a related long-standing open problem in probability theory.Comment: V1: 43 pages, single column, 8 figures. V2: titled changed; added proof-overview and accompanying figure; 50 pages, single column, 9 figure

Do more placement officers lead to lower unemployment? : evidence from Germany

"In this paper we examine the effect of a pilot project of the German Federal Employment Agency, where in 14 German local employment offices the caseload (number of unemployed per caseworker) was significantly reduced. Since the participating local offices were not chosen at random, we have to take into account potential selection bias. Therefore, we rely on a combination of matching and a difference-in-differences estimator. We use two indicators of the offices' success (unemployment rate, growth of the number of SCIII clients). Our results indicate a positive effect of a lower caseload on both outcome variables." (Author's abstract, IAB-Doku) ((en))Arbeitsvermittlung - Erfolgskontrolle, Arbeitsvermittler - Modellversuch, berufliche Reintegration - Quote, Arbeitslosenquote, Arbeitsvermittlerquote

The Economic Effects of Constitutions: Replicating – and Extending – Persson and Tabellini

Persson and Tabellini (2003) show that presidential regimes and majoritarian election systems have important effects on fiscal policy, government effectiveness and productivity. Here, their dataset is extended in a number of ways: the number of countries included is increased from 85 to up to 116, and more recent data for both government effectiveness and productivity are used. In replicating and extending their analyses, we find that the effect of presidential regimes on all three groups of economic variables vanishes almost entirely. With regard to electoral systems, the original results are largely confirmed: majoritarian (as opposed to proportional) electoral systems lead to lower government expenditure, lower levels of rent seeking but also lower output per worker. The institutional details such as the proportion of candidates that are not elected via party lists and the district magnitude have proved to be of particular importance. The question whether societies can improve their lot by choosing specific constitutional rules remains open.

Services Grids in Industry – On-Demand Provisioning and Allocation of Grid-Based Business Services

Over the last few years Grid computing has attracted considerable attention from the industry, because it offers opportunities for new on-demand business services for enterprises. In this article, we depict the current trend of enterprises to source Grid services offered by third-party utility providers on a use-on-demand, pay-per-use basis, thus leading to faster IT response to changing business needs. We outline the emerging expansion of Grid computing in industry and discuss the significant challenges still needing to be solved to further promote the adoption of Grid technology in the business domain

Acoustic and Large Eddy Simulation studies of azimuthal modes in annular combustion chambers

The objectives of this paper are the description of azimuthal instability modes found in annular combus- tion chambers using two numerical tools: (1) Large Eddy Simulation (LES) methods and (2) acoustic solv- ers. These strong combustion instabilities are difficult to study experimentally and the present study is based on a LES of a full aeronautical combustion chamber. The LES exhibits a self-excited oscillation at the frequency of the first azimuthal eigenmode. The mesh independence of the LES is verified before ana- lysing the nature of this mode using various indicators over more than 100 cycles: the mode is mostly a pure standing mode but it transitions from time to time to a turning mode because of turbulent fluctu- ations, confirming experimental observations and theoretical results. The correlation between pressure and heat release fluctuations (Rayleigh criterion) is not verified locally but it is satisfied when pressure and heat release are averaged over sectors. LES is also used to check modes predicted by an acoustic Helmholtz solver where the flow is frozen and flames are modelled using a Flame Transfer Function (FTF) as done in most present tools. The results in terms of mode structure compare well confirming that the mode appearing in the LES is the first azimuthal mode of the chamber. Moreover, the acoustic solver provides stability maps suggesting that a reduction of the time delay of the FTF would be enough to sta- bilise the mode. This is confirmed with LES by increasing the flame speed and verifying that this modi- fication leads to a damped mode in a few cycles