Collaborative Categorization on the Web

Collaborative categorization is an emerging direction for research and innovative applications. Arguably, collaborative categorization on the Web is an especially promising emerging form of collaborative Web systems because of both, the widespread use of the conventional Web and the emergence of the Semantic Web providing with more semantic information on Web data. This paper discusses this issue and proposes two approaches: collaborative categorization via category merging and collaborative categorization proper. The main advantage of the first approach is that it can be rather easily realized and implemented using existing systems such as Web browsers and mail clients. A prototype system for collaborative Web usage that uses category merging for collaborative categorization is described and the results of field experiments using it are reported. The second approach, called collaborative categorization proper, however, is more general and scales better. The data structure and user interface aspects of an approach to collaborative categorization proper are discussed

Subsidies and Exports in Germany First Evidence from Enterprise Panel Data

We use newly available representative panel data for manufacturing enterprises in West and East Germany to investigate the link between production-related subsidies and exports. We document that only a small fraction of enterprises is subsidized, and that exports and subsidies are positively related. Using a matching approach to investigate the causal effect of subsidies on export activities we find no impact of subsidies on the probability to start exporting, and only weak evidence for an impact of subsidies on the share of exports in total sales in West Germany but no evidence in East Germany.Subsidies, export, Germany, enterprise panel data

Consumption habits and humps : [Version 23 June 2013]

We show that the optimal consumption of an individual over the life cycle can have the hump shape (inverted U-shape) observed empirically if the preferences of the individual exhibit internal habit formation. In the absence of habit formation, an impatient individual would prefer a decreasing consumption path over life. However, because of habit formation, a high initial consumption would lead to high required consumption in the future. To cover the future required consumption, wealth is set aside, but the necessary amount decreases with age which allows consumption to increase in the early part of life. At some age, the impatience outweighs the habit concerns so that consumption starts to decrease. We derive the optimal consumption strategy in closed form, deduce sufficient conditions for the presence of a consumption hump, and characterize the age at which the hump occurs. Numerical examples illustrate our findings. We show that our model calibrates well to U.S. consumption data from the Consumer Expenditure Survey

Numerical calculation of the complex berry phase in non-Hermitian systems

We numerically investigate topological phases of periodic lattice systems in tight-binding description under the influence of dissipation. The effects of dissipation are effectively described by $\mathcal{PT}$-symmetric potentials. In this framework we develop a general numerical gauge smoothing procedure to calculate complex Berry phases from the biorthogonal basis of the system's non-Hermitian Hamiltonian. Further, we apply this method to a one-dimensional $\mathcal{PT}$-symmetric lattice system and verify our numerical results by an analytical calculation.Comment: 7 pages, 3 figures, minor modifications in the final versio

Cryoglobulinaemic vasculitis: classification and clinical and therapeutic aspects

Cryoglobulinaemia may cause cutaneous vasculitis and glomerulonephritis, potentially leading to end stage renal failure. An important proportion of cryoglobulinaemias are secondary to hepatitis C virus infection. Emerging antiviral treatment options offer a chance for causal therapy of these cases of cryoglobulinaemia. This review summarises the classification and clinical and therapeutic aspects of cryoglobulinaemic vasculitis and glomerulonephritis

Der Entwicklungsaufwand der Anwendungsintegration. Eine empirische Untersuchung der Einflussfaktoren

In den vergangenen Jahren hat die Anwendungsintegration zunehmend an praktischer Bedeutung gewonnen. Gleichwohl ist die wissenschaftliche Auseinandersetzung mit dieser spezifischen Ausprägung der Softwareentwicklung erst wenig fortgeschritten. Unter anderem sind keine geeigneten Methoden zur Schätzung des Entwicklungsaufwands der Anwendungsintegration verfügbar. Diese unzureichende methodische Unterstützung der Aufwandschätzung wird als wichtiger Grund dafür angesehen, dass viele Integrationsvorhaben durch große Termin- und Kostenüberschreitungen gekennzeichnet sind. Die Frage, welche Faktoren in die Aufwandschätzung einbezogen werden müssen, konnte bislang aufgrund des Mangels angemessener empirischer oder theoretischer Erkenntnisse nicht zuverlässig beantwortet werden. Diese Arbeit leistet einen Beitrag zur Behebung dieses Mangels. In einer empirischen Untersuchung wurden erstmals die Erfahrungswerte und Einschätzungen kompetenter Praktiker zu den maßgeblichen Einflussfaktoren auf den Entwicklungsaufwand der Anwendungsintegration in systematischer Weise erhoben und inhaltlich ausgewertet. Durch die angewandte Forschungsmethode, eine qualitative und idiographische Variante der Repertory Grid Technique, konnte ein umfangreicher Katalog persönlicher Konstrukte erhoben werden, der einen wertvollen wissenschaftlichen Beitrag zur Untersuchung der Einflussfaktoren auf den Entwicklungsaufwand der Anwendungsintegration darstellt. Die Untersuchungsergebnisse wurden darüber hinaus in eine Checkliste für die Durchführung von Aufwandschätzungen überführt. Auf diese Weise leistet die vorgelegte Arbeit einen unmittelbaren Beitrag zur Lösung des aufgezeigten Praxisproblems: sie bietet erstmalig eine spezifische Unterstützung zur Schätzung des Entwicklungsaufwands der Anwendungsintegration

A tool to model 3D coarse-root development with annual resolution

Dynamic root-development models are indispensable for biomechanical and biomass allocation studies, and also play an important role in understanding slope stability. There are few root-development models in the literature, and there is a specific lack of dynamic models. Therefore, the aim of this study is to develop a 3D growth-development model for coarse roots, which is species independent, as long as annual rings are formed. In order to implement this model, the objectives are (I) to interpolate annual growth layers, and (II) to evaluate the interpolations and annual volume computations. The model developed is a combination of 3D laser scans and 2D tree-ring data. A FARO laser ScanArm is used to acquire the coarse-root structure. A MATLAB program then integrates the ring-width measurements into the 3D model. A weighted interpolation algorithm is used to compute cross sections at any point within the model to obtain growth layers. The algorithm considers both the root structure and the ring-width data. The model reconstructed ring profiles with a mean absolute error for mean ring chronologies of <9% and for single radii of <20%. The interpolation accuracy was dependent on the number of input sections and root curvature. Total volume computations deviated by 3.5-6.6% from the reference model. A new robust root-modelling tool was developed which allows for annual volume computations and sophisticated root-development analyse

Incorporating 2D tree-ring data in 3D laser scans of coarse-root systems

In times of global change biomass calculations and the carbon cycle is gaining in importance. Forests act as carbon sinks and hence, play a crucial role in worlds and forests carbon budgets. Unfortunately, growth models and biomass calculations existing so far mainly concentrate on the above-ground part of trees. For this reason, the aim of the present study is to develop an annually resolved 3D growth model for tree roots, which allows for reliable biomass calculations and can later be combined with above-ground models. A FARO scan arm was used to measure the surface of a tree-root segment. In addition, ring-width measurements were performed manually on sampled cross sections using WinDENDRO. The main goal of this study is to model root growth on an annual scale by combining these data sets. In particular, a laser scan arm was tested as a device for the realistic reproduction of tree-root architecture, although the first evaluation has been performed for a root segment rather than for an entire root system. Deviations in volume calculations differed between 5% and 7% from the actual volume and varied depending on the used modeling technique. The model with the smallest deviations represented the structure of the root segment in a realistic way and distances and diameter of cross sections were acceptable approximations of the real values. However, the volume calculations varied depending on object complexity, modeling technique and order of modeling steps. In addition, it was possible to merge tree-ring borders as coordinates into the surface model and receive age information in connection with the spatial allocation. The scan arm was evaluated as an innovative and applicable device with high potential for root modeling. Nevertheless, there are still many problems connected with the scanning technique which have an influence on the accuracy of the model but are expected to improve with technical progres