The European Social Model and eastern enlargement

"The European Social Model (ESM) is increasingly becoming a model of integration policy. The idea is based on a combination of economic efficiency, in the sense of high productivity, competition and economic growth, and a high level of employment on the one hand together with social cohesion on the other hand. At the same time the ESM is understood as a dynamic model in evolution, whose development is influenced by global, European and national processes, including eastern enlargement. With the accession of the eight Central and Eastern European countries to the European Union, the economic and social disparities between the now 25 EU Member States have grown considerably. On the basis of theoretical and empirical literature this paper develops answers to the following questions in particular: will there be a gradual erosion of the ESM, are there prospects of convergence or are new vectors developing in the enlarged field of power? The authors reach the conclusion that the old and the new Member States, starting out from different historical experiences in the past decades and different levels of production and productivity, will have to withstand structurally similar challenges in the foreseeable future if they wish to achieve economic efficiency and social cohesion simultaneously. From the perspective of the new Member States, which come from an egalitarian tradition, there is every reason to believe that the majority of the population desires social cohesion and will demand it. Together with the diverse integration advantages of enlargement, a successful catching-up process in the new Member States provides good preconditions for the preservation and productive development of the ESM." (Author's abstract, IAB-Doku) ((en))EU-Osterweiterung, regionale Disparität, europäische Sozialpolitik, europäische Integration, Konvergenz, Arbeitsmarktentwicklung, Wirtschaftsentwicklung, Produktivitätsentwicklung, soziale Integration, Integrationspolitik, Leitbild, Europäische Union, Osteuropa, Mitteleuropa

An O(n^{2.75}) algorithm for online topological ordering

We present a simple algorithm which maintains the topological order of a directed acyclic graph with n nodes under an online edge insertion sequence in O(n^{2.75}) time, independent of the number of edges m inserted. For dense DAGs, this is an improvement over the previous best result of O(min(m^{3/2} log(n), m^{3/2} + n^2 log(n)) by Katriel and Bodlaender. We also provide an empirical comparison of our algorithm with other algorithms for online topological sorting. Our implementation outperforms them on certain hard instances while it is still competitive on random edge insertion sequences leading to complete DAGs.Comment: 20 pages, long version of SWAT'06 pape

Adaptive Wavelet Methods for Inverse Problems: Acceleration Strategies, Adaptive Rothe Method and Generalized Tensor Wavelets

In general, inverse problems can be described as the task of inferring conclusions about the cause u from given observations y of its effect. This can be described as the inversion of an operator equation K(u) = y, which is assumed to be ill-posed or ill-conditioned. To arrive at a meaningful solution in this setting, regularization schemes need to be applied. One of the most important regularization methods is the so called Tikhonov regularization. As an approximation to the unknown truth u it is possible to consider the minimizer v of the sum of the data error K(v)-y (in a certain norm) and a weighted penalty term F(v). The development of efficient schemes for the computation of the minimizers is a field of ongoing research and a central Task in this thesis. Most computation schemes for v are based on some generalized gradient descent approach. For problems with weighted lp-norm penalty terms this typically leads to iterated soft shrinkage methods. Without additional assumptions the convergence of these iterations is only guaranteed for subsequences, and even then only to stationary points. In general, stationary points of the minimization problem do not have any regularization properties. Also, the basic iterated soft shrinkage algorithm is known to converge very poorly in practice. This is critical as each iteration step includes the application of the nonlinear operator K and the adjoint of its derivative. This in itself may already be numerically demanding. This thesis is concerned with the development of strategies for the fast computation of the solution of inverse problems with provable convergence rates. In particular, the application and generalization of efficient numerical schemes for the treatment of the arising nonlinear operator equations is considered. The first result of this thesis is a general acceleration strategy for the iterated soft thresholding iteration to compute the solution of the inverse problem. It is based on a decreasing strategy for the weights of the penalty term. The new method converges with linear rate to a global minimizer. A very important class of inverse problems are parameter identification problems for partial differential equations. As a prototype for this class of problems the identification of parameters in a specific parabolic partial differential equation is investigated. The arising operators are analyzed, the applicability of Tikhonov Regularization is proven and the parameters in a simplified test equation are reconstructed. The parabolic differential equations are solved by means of the so called horizontal method of lines, also known as Rothes method. Here the parabolic problem is interpreted as an abstract Cauchy problem. It is discretized in time by means of an implicit scheme. This is combined with a discretization of the resulting system of spatial problems. In this thesis the application of adaptive discretization schemes to solve the spatial subproblems is investigated. Such methods realize highly nonuniform discretizations. Therefore, they tend to require much less degrees of freedom than classical discretization schemes. To ensure the convergence of the resulting inexact Rothe method, a rigorous convergence proof is given. In particular, the application of implementable asymptotically optimal adaptive methods, based on wavelet bases, is considered. An upper bound for the degrees of freedom of the overall scheme that are needed to adaptively approximate the solution up to a prescribed tolerance is derived. As an important case study, the complexity of the approximate solution of the heat equation is investigated. To this end a regularity result for the spatial equations that arise in the Rothe method is proven. The rate of convergence of asymptotically optimal adaptive methods deteriorates with the spatial dimension of the problem. This is often called the curse of dimensionality. One way to avoid this problem is to consider tensor wavelet discretizations. Such discretizations lead to dimension independent convergence rates. However, the classical tensor wavelet construction is limited to domains with simple product geometry. Therefor, in this thesis, a generalized tensor wavelet basis is constructed. It spans a range of Sobolev spaces over a domain with a fairly general geometry. The construction is based on the application of extension operators to appropriate local bases on subdomains that form a non-overlapping domain decomposition. The best m-term approximation of functions with the new generalized tensor product basis converges with a rate that is independent of the spatial dimension of the domain. For two- and three-dimensional polytopes it is shown that the solution of Poisson type problems satisfies the required regularity condition. Numerical tests show that the dimension independent rate is indeed realized in practice

Efficiently Generating Geometric Inhomogeneous and Hyperbolic Random Graphs

Hyperbolic random graphs (HRG) and geometric inhomogeneous random graphs (GIRG) are two similar generative network models that were designed to resemble complex real world networks. In particular, they have a power-law degree distribution with controllable exponent beta, and high clustering that can be controlled via the temperature T. We present the first implementation of an efficient GIRG generator running in expected linear time. Besides varying temperatures, it also supports underlying geometries of higher dimensions. It is capable of generating graphs with ten million edges in under a second on commodity hardware. The algorithm can be adapted to HRGs. Our resulting implementation is the fastest sequential HRG generator, despite the fact that we support non-zero temperatures. Though non-zero temperatures are crucial for many applications, most existing generators are restricted to T = 0. We also support parallelization, although this is not the focus of this paper. Moreover, we note that our generators draw from the correct probability distribution, i.e., they involve no approximation. Besides the generators themselves, we also provide an efficient algorithm to determine the non-trivial dependency between the average degree of the resulting graph and the input parameters of the GIRG model. This makes it possible to specify the desired expected average degree as input. Moreover, we investigate the differences between HRGs and GIRGs, shedding new light on the nature of the relation between the two models. Although HRGs represent, in a certain sense, a special case of the GIRG model, we find that a straight-forward inclusion does not hold in practice. However, the difference is negligible for most use cases

Rescue of myeloid lineage-committed preprogenitor cells from cytomegalovirus-infected bone marrow stroma

The effect of murine cytomegalovirus on myelopoiesis was studied in long-term bone marrow culture to find an in vitro correlate for the lethal virus interference with bone marrow reconstitution (W. Mutter, M. J. Reddehase, F. W. Busch, H.-J. Bühring, and U. H. Koszinowski, J. Exp. Med. 167:1645-1658, 1988). The in vitro generation of granulocyte-monocyte progenitors (CFU-GM) discontinued after infection of the stromal cell layer, whereas the proliferation and differentiation of CFU-GM to granulocyte-monocyte colonies remained unaffected. A protocol was established to probe the functional integrity of earlier hematopoietic cells. Pre-CFU-GM (the progenitors of the CFU-GM) could be recovered from an infected bone marrow donor culture by transfer onto an inductive recipient stromal cell layer. Thus, at least in vitro, infection of bone marrow stroma appears to be the only cause of the defect in myelopoiesis

The Fen1 extrahelical 3′‐flap pocket is conserved from archaea to human and regulates DNA substrate specificity

Fen1 is a key enzyme for the maintenance of genetic stability in archaea and eukaryotes and is classified as a tumor suppressor. Very recent structural data obtained from Archaeoglobus fulgidus Fen1 suggest that an extrahelical 3′‐flap pocket is responsible for substrate specificity, by binding to the unpaired 3′‐flap and by opening and kinking the DNA. Since the extrahelical 3′‐flap pocket in archaeal Fen1 contains seven amino acids that are conserved to a great extent in human Fen1, we have mutated the four conserved or all seven amino acids in the human Fen1 extrahelical 3′‐flap pocket to alanine. Our data suggest that the human extrahelical 3′‐flap pocket mutants have lost substrate specificity to the double‐flap DNA. Moreover, loss of high affinity for the unpaired 3′‐flap suggests that the extrahelical 3′‐flap pocket is essential for recognition and processing of the ‘physiological' template. Human PCNA could stimulate the human Fen1 extrahelical 3′‐flap pocket mutants but not restore their specificity. Thus the substrate specificity of Fen1 has been functionally conserved over a billion years from archaea to huma

Entwicklung und Ursachen von mis-match-Arbeitslosigkeit in Westdeutschland

"Der Aufsatz beschäftigt sich mit den Fragen: (a) Hat mis-match-Arbeitslosigkeit im Zuge des jüngsten konjunkturellen Aufschwungs in Westdeutschland zugenommen? (b) (Wenn ja,) welche Ursachen sind dafür maßgeblich gewesen? (c) Welche arbeitsmarktpolitischen Konsequenzen ergeben sich daraus? Zu (a) werden zwei Ansätze vorgestellt: Aus einer empirisch-statistisch orientierten Darstellung der Ausgleichsprozesse zwischen offenen Stellen und Arbeitslosen für die Jahre 1983 und 1990 wird gefolgert, daß es sehr viel seltener gelingt, Arbeitslose auf vakante Arbeitsplätze zu vermitteln. Sichere makroökonomische Schlüsse können jedoch daraus nicht gezogen werden. Deshalb wird in einem zweiten Anlauf das Konzept der Beveridge-Kurve anhand eines theoretisch-mathematischen Modells analysiert. Hieraus werden weitere Indizien für zunehmende mis-match-Arbeitslosigkeit abgeleitet. Multiple Regressionsanalysen zur Erklärung der Laufzeit offener Stellen und der Dauer der Arbeitslosigkeit bilden das methodische Instrumentarium zur Ursachenanalyse (b). Daraus ergibt sich insgesamt eine andere - oder jedenfalls modifizierte Sichtweise von mis-match-Arbeitslosigkeit als die traditionelle. Jene rückte die Profildiskrepanzen zwischen Arbeitslosen und offenen Stellen in den Vordergrund. Den größten Einfluß auf die Dauer der Arbeitslosigkeit haben nach unseren Ergebnissen vielmehr die Merkmale, die auf eine geringere individuelle Leistungsfähigkeit schließen lassen, wie Alter und gesundheitliche Einschränkungen. Die bisherigen unterschiedlichen technischen und organisatorischen Ausgestaltungen der Vermittlungstätigkeit in den Arbeitsämtern werden davon fast vollständig überlagert. Angesichts des empirischen Befundes 'mis-match-Arbeitslosigkeit als Ergebnis von Sortierprozessen auf beiden Marktseiten' steht Arbeitsmarktausgleichspolitik (c) vor größeren Schwierigkeiten als bisher. Diese werden durch die Zulassung privater Vermittler selbst nicht überwunden. Sie können insgesamt nicht allein durch Verbesserung der Vermittlungsleistung gemeistert werden, vielmehr sind zusätzliche Hilfen zur Eingliederung in Problemsituationen vor allem für Ältere nötiger denn je. Hier werden in Übereinstimmung mit Leitlinien zur Weiterentwicklung der Arbeitsvermittlung und Arbeitsberatung der Bundesanstalt für Arbeit insbesondere drei Ansatzpunkte für die Weiterentwicklung aus der Sicht der Ergebnisse dieser Untersuchung und unter Einbeziehung jüngerer Forschungsergebnisse diskutiert und in ihrer Notwendigkeit unterstrichen: - Ausbau der Kontakte der Arbeitsvermittlung und Arbeitsberatung zu Klein- und Mittelbetrieben, - Konzentration der Vermittler auf das eigentliche Vermittlungsgeschäft bei Aufrechterhaltung des Dienstleistungsangebots der Arbeitsförderung aus einer Hand, - Nutzung der Unschärfen des Arbeitsmarktes/der arbeitnehmerseitigen Flexibilitäts- und arbeitgeberseitigen Substitutionsspielräume." (Autorenreferat)strukturelle Arbeitslosigkeit, Arbeitslosigkeit - Determinanten, mismatch, Arbeitslosigkeit - Dauer, offene Stellen, Arbeitsvermittlung - Quote, Arbeitsmarktpolitik, Arbeitsmarktgleichgewicht, Westdeutschland, Bundesrepublik Deutschland