873 publications from this institution
The authors report on a postirradiation osteosarcoma of the calvicule in a patient treated for thyroid cancer. The total absorbed dose to the right calvicule was estimated 149 Gy 60 Co and 18 MeV elektron beam). The findings are demonstrated on plain radiographs, CT-scan and bone scintigraphy. The literature on this subject is reviewed and the possible pathogenesis discussed.
This paper exposes problems of the commonly used technique of splitting the available data in neural spatial interaction modelling into training, validation, and test sets that are held fixed and warns about drawing too strong conclusions from such static splits. Using a bootstrapping procedure, we compare the uncertainty in the solution stemming from the data splitting with model specific uncertainties such as parameter initialization. Utilizing the Austrian interregional telecommunication traffic data and the differential evolution method for solving the parameter estimation task for a fixed topology of the network model [ i.e. J = 9] this paper illustrates that the variation due to different resamplings is significantly larger than the variation due to different parameter initializations. This result implies that it is important to not over-interpret a model, estimated on one specific static split of the data.(This abstract was borrowed from another version of this item.)
This paper presents a methodology for neural spatial interaction modelling. Particular emphasis is laid on design, estimation and performance issues in both cases, unconstrained and singly constrained spatial interaction. Families of classical neural network models, but also less classical ones such as product unit neural network models are considered. Some novel classes of product unit and summation unit models are presented for the case of origin or destination constrained spatial interaction flows. The models are based on a modular connectionist architecture that may be viewed as a linked collection of functionally independent neural modules with identical feedforward topologies, operating under supervised learning algorithms. Parameter estimation is viewed as Maximum Likelihood (ML) learning. The nonconvex nature of the loss function makes the Alopex procedure, a global search procedure, an attractive and appropriate optimising scheme for ML learning. A benchmark comparison against the classical gravity models illustrates the superiority of both, the unconstrained and the origin constrained, neural network model versions in terms of generalization performance measured by Kullback and Leibler`s information criterion. Hereby, the authors make use of the bootstrapping pairs approach to overcome the largely neglected problem of sensitivity to the specific splitting of the data into training, internal validation and testing data sets, and to get a better statistical picture of prediction variability of the models. Keywords: Neural spatial interaction models, origin constrained or destination constrained spatial interaction, product unit network, Alopex procedure, boostrapping, benchmark performance tests.
During the last few years, the economic landscape of Europe has changed dramatically, both in the East and in the West. In Eastern Europe, the peaceful revolutions — except Yugoslavia — are among the most dramatic events of the current epoch. A central...
This paper explores the relationship between household income inequality and macroeconomic uncertainty in the United States. Using a novel large-scale macroeconometric model, we shed light on regional disparities of inequality responses to a national uncertainty shock. The results suggest that income inequality decreases in most states, with a pronounced degree of heterogeneity in terms of the dynamic responses. By contrast, some few states, mostly located in the Midwest, display increasing levels of income inequality over time. Forecast error variance and historical decompositions highlight the importance of uncertainty shocks in explaining income inequality in most regions considered. Finally, we explain differences in the responses of income inequality by means of a simple regression analysis. These regressions reveal that the income composition as well as labor market fundamentals determine the directional pattern of the dynamic responses.
This paper contains an analysis of a multiregional labour-supply model for Austria. In the approach suggested here attempts are made to combine the advantages of random-utility-based discrete choice theory and partial reduced-form estimation. Two recursive submodels, the labour-force participation submodel, and the commuting and employment submodel, are developed. Three different types of model specifications at the mesolevel are used to analyse the consequences of choosing a spatial framework of overlapping regional labour markets upon the model parameters, to investigate the usefulness of the model approach in relation to different regionalisation variants, and to carry out a sensitivity analysis with respect to the effects of the model parameters used to delineate the labour-market regions.
This article investigates the impact of knowledge capital stocks on total factor productivity (TFP) through the lens of the knowledge capital model proposed by Griliches (1979), augmented with a spatially discounted cross‐region knowledge spillover pool variable. The objective is to shift attention from firms and industries to regions and to estimate the impact of cross‐region knowledge spillovers on TFP in Europe. The dependent variable is the region‐level TFP, measured in terms of the superlative TFP index suggested by Caves, Christensen, and Diewert (1982). This index describes how efficiently each region transforms physical capital and labor into output. The explanatory variables are internal and out‐of‐region stocks of knowledge, the latter capturing the contribution of cross‐region knowledge spillovers. We construct patent stocks to proxy annual regional knowledge capital stocks for N=203 regions during 1997–2002. In estimating the effects, we implement a spatial panel data model that controls for spatial autocorrelation as well as individual heterogeneity across regions. The findings provide a fairly remarkable confirmation of the role of knowledge capital contributing to productivity differences among regions and add an important spatial dimension to discussions in the literature by showing that productivity effects of knowledge spillovers increase with geographic proximity.
This article presents a theoretical growth model that accounts for technological interdependence among regions in a Mankiw-Romer-Weil world. The reasoning behind the theoretical work is that technological ideas cannot be fully appropriated by investors and these ideas may diffuse and increase the productivity of other firms. We link the diffusion of ideas to spatial proximity and allow ideas to flow to nearby regional economies. Through the magic of solving for the reduced form of the theoretical model and the magic of spatial autoregressive processes, the simple dependence on a small number of neighboring regions leads to a reduced form theoretical model and an associated empirical model where changes in a single region can potentially impact all other regions. This implies that conventional regression interpretations of the parameter estimates would be wrong. The proper way to interpret the model has to rely on matrices of partial derivatives of the dependent variable with respect to changes in the Mankiw-Romer-Weil variables, using scalar summary measures for reporting the estimates of the marginal impacts from the model. The summary impact measure estimates indicate that technological interdependence among the European regions works through physical rather than human capital externalities.
Spatial interaction models of the gravity type are widely used to describe origin-destination flows. They draw attention to three types of variables to explain variation in spatial interactions across geographic space: variables that characterize the origin region of interaction, variables that characterize the destination region of interaction, and variables that measure the separation between origin and destination regions. A violation of standard minimal assumptions for least squares estimation may be associated with two problems: spatial autocorrelation within the residuals, and spatial autocorrelation within explanatory variables. This paper compares a spatial econometric solution with the spatial statistical Moran eigenvector spatial filtering solution to accounting for spatial autocorrelation within model residuals. An example using patent citation data that capture knowledge flows across 257 European regions serves to illustrate the application of the two approaches.
Zusammenfassung Teil I Vor der Durchführung einer Radiosynoviorthese (RSO) bei entzündlichen Gelenkerkrankungen oder einer pigmentierten villonodulären Synovitis muss grundsätzlich abgeklärt werden, ob eine Thromboseprophylaxe erforderlich ist, oder eine bereits eingeleitete Antikoagulationstherapie unterbrochen werden soll. Nach vorliegenden Publikationen besteht nach einer intra-artikulären Injektion bei einer laufenden Antikoagulationstherapie keine signifikant erhöhte Blutungsgefahr. Deshalb ist eine Unterbrechung oder Einleitung einer Bridgingtherapie nicht notwendig. Anderenfalls sollte dies mit dem primär behandelnden Fachkollegen abgesprochen werden. Nach den Leitlinien chirurgischer Fachgesellschaften wird eine intra-artikuläre Injektion zu den sehr niedrig einzuordnenden Risikofaktoren für eine Thrombose gerechnet. Nach Ausschluss zusätzlicher angeborener oder erworbener Risikofaktoren kann eine Thromboseprophylaxe unterbleiben. Aus juristischer Sicht ist es erforderlich, die Patienten besonders über die Vor- und möglichen Nachteile eines entsprechenden Vorgehens aufzuklären. Teil II Ärztliche Berufsausübung ist auch mit forensischen Risiken behaftet. Dies betrifft insbesondere etwaige haftungs- und strafrechtliche Konsequenzen, welche es zu vermeiden gilt. Infolgedessen sollte jede Ärztin und jeder Arzt auch die rechtlichen Anforderungen, welche an die Berufsausübung gestellt sind, kennen. So muss sich die Patientenbehandlung als solche sorgfaltspflichtgerecht bzw. lege artis, d. h. gemäß aktuell geltendem medizinischen Standard gestalten. Zudem bedarf es der adäquaten Aufklärung des Patienten bez. Behandlungsmaßnahmen, welche in seine körperliche Integrität eingreifen. Unter beiden Aspekten kommt der Behandlungsdokumentation – unbeschadet ihrer therapeutischen Funktion und rechtlicher Verpflichtung zur Vornahme – erhebliche rechtspraktische Bedeutung zu. Denn zivilrechtlich resultieren aus mangelnder bzw. fehlender Dokumentation Beweisnachteile für die Behandlerseite. Auch die Einhaltung rechtlicher Maßgaben optimiert zum einen die Patientenbehandlung und senkt zum anderen forensische Risiken.
In this paper we present a formal analysis that incorporates returns to transportation into a Ricardian framework to predict trade patterns. The important point gained from this analysis is that increasing returns to transportation, coupled with appropriate distances between trading partners, can be shown to reverse Ricardian predictions even when there are no international differences in tastes, technology, or factor endowments. Additional gains from trade may emerge from reductions in aggregate delivery costs owing to scale economies.
This paper explores the contribution of knowledge capital to total factor productivity differences among regions within a regression framework. We provide an econometric derivation of the relationship and show that the presence of latent/unobservable regional knowledge capital leads to a model relationship that includes both spatial and technological dependence. This model specification accounts for both spatial and technological dependence between regions, which allows us to quantify spillover impacts arising from both types of interaction. Sample data on 198 NUTS-2 regions spanning the period from 1997 to 2002 was used to empirically test the model, to measure both direct and indirect effects of knowledge capital on regional total factor productivity, and to assess the relative importance of knowledge spillovers from spatial versus technological proximity.
No abstract is provided for this article.
Within the EU-SAFEST project, the Swedish Radiation Safety Authority (SSM) proposed to perform tests on molten corium-concrete interaction (MCCI) with basaltic concrete and BWR-specific corium, characterized by a higher Zr/U ratio than PWR corium. These tests (denoted SSM-1a/2b/2c/3) were carried out in Framatome’s SICOPS facility in Erlangen. Once the melt initially containing ≈75 wt% UO2, ≈17 wt% ZrO2, was generated and its interaction with the concrete had started, metallic Zr was subsequently added to the melt from the top. All tests showed a fast concrete ablation by the melt, faster than in previous SICOPS experiments without Zr addition, most likely due to the higher temperature of the melt caused by the Zr oxidation. The absence of crusts and even erosion profiles at the bottom seen during post-test examination support the assumption of a homogeneously mixed melt pool during MCCI. In the presence of high melt temperatures and the vivid mixing by rising concrete decomposition gases, local crusts between melt and concrete should not be stable and no evidence for them has been found. As the formation of such crusts is seen as the main potential mechanism for anisotropic concrete ablation in the early stages of an MCCI, the investigated conditions with Zr being present in the melt can be considered capable of suppressing this effect. This is important since the core melt, after its release from the RPV, typically contains a high fraction of non-oxidized Zr. While no crusts were found at the interface, sampling in the late phase of the SSM-3 test revealed evidence for the formation of a kind of transition zone between melt and concrete. This conclusion was drawn based on tactile feedback during sampling from the bottom of the melt pool where a soft/viscous zone could be felt and from the appearance of taken samples including small solid aggregates from the transition zone. Gas measurements during SSM-3 showed a significant H2 production, due to the reaction of water from the concrete with metallic zirconium. The peaks in the H2 concentration occurred when the concrete erosion velocities were highest. This confirms that, even at high erosion and superficial gas rates, the Zr in the bulk is still capable of reducing the percolating steam.
Die deutsche, österreichische und schweizerische wissenschaftliche Gesellschaft für Nuklearmedizin legen eine 3-Länder-Leitlinie vor, bei der es sich um eine S1-Leitlinie und damit um eine Handlungsempfehlung handelt [1].
