Linear Estimating Equations for Exponential Families with Application to Gaussian Linear Concentration Models

In many families of distributions, maximum likelihood estimation is intractable because the normalization constant for the density which enters into the likelihood function is not easily available. The score matching estimator of Hyv\"arinen (2005) provides an alternative where this normalization constant is not required. The corresponding estimating equations become linear for an exponential family. The score matching estimator is shown to be consistent and asymptotically normally distributed for such models, although not necessarily efficient. Gaussian linear concentration models are examples of such families. For linear concentration models that are also linear in the covariance we show that the score matching estimator is identical to the maximum likelihood estimator, hence in such cases it is also efficient. Gaussian graphical models and graphical models with symmetries form particularly interesting subclasses of linear concentration models and we investigate the potential use of the score matching estimator for this case

Stellenwert der Ausbildungs- und Beschäftigungskrise in der internationalen Jugenddiskussion

"Die internationale Jugenddiskussion verändert sich in Stil und Inhalten zunehmend unter dem Druck der Beschäftigungskrise. Der Tenor dieser Diskussion wird im wesentlichen von den internationalen, nichtgouvernementalen Jugendorganisationen und den im Europäischen Jugendrat (CENYC) zusammengeschlossenen Nationalkommittees für Jugendarbeit bestimmt, die sich sowohl im Jugendforum der Europäischen Gemeinschaften als auch im Europäischen Jugendwerk und Europäischen Jugendzentren des Europarates in den letzten Jahren spezielle Vertretungsrechte erkämpft haben. Die ursprüngliche Orientierung dieser Diskussion an Konzepten der emanzipatorischen Jugendarbeit geht langsam verloren; aus Jugendarbeit als Freiraum gegenüber Schule und Familie wird in vielen europäischen Ländern zunehmend ein neuer Typ von Sozialarbeit. Jugendorganisationen müssen in wachsendem Maße ihren Beitrag zur Gesellschaft auf dem Hintergrund der Beschäftigungskrise legitimieren; dies hat Auswirkungen auf ihre Arbeitsweise, ihr Personal und ihre Funktion. Ihre um das soziale Experiment zentrierte Bildungsfunktion und ihr informeller Charakter verschwinden nach und nach. Diese Organisationen nehmen gegenüber internationalen Organisationen allmählich die Haltung einer affirmativen Jugendlobby ein, ohne die Chance zu sehen, auf Existenz und Handlungsweise dieser Einrichtungen irgendeinen Einfluß ausüben zu können. Dies ist die eigentliche Krise des Konzepts der "Partizipation" im Internationalen Jahr der Jugend." (Autorenreferat)Jugendarbeit, Ausbildung - Krise, Beschäftigung - Krise, Jugendorganisation, Sozialarbeit

Fingerprint Analysis with Marked Point Processes

We present a framework for fingerprint matching based on marked point process models. An efficient Monte Carlo algorithm is developed to calculate the marginal likelihood ratio for the hypothesis that two observed prints originate from the same finger against the hypothesis that they originate from different fingers. Our model achieves good performance on an NIST-FBI fingerprint database of 258 matched fingerprint pairs

Exact Algorithms for Solving Stochastic Games

Shapley's discounted stochastic games, Everett's recursive games and Gillette's undiscounted stochastic games are classical models of game theory describing two-player zero-sum games of potentially infinite duration. We describe algorithms for exactly solving these games

Four phases of video streaming: A case study of medical teaching

This article examines video streaming in teaching situations with varying degrees of student activation ranging from lectures to team-based learning. The article is a case study of the implementation of video streaming at the Department of Medicine, Aarhus University. The aim of the article is to develop a model of video streaming in student-centered teaching. The research question is what characterizes the phases of video streaming in relation to student-centered teaching? The article develops a model with four phases of video streaming based on the case study and the literature on learning design. The article argues that both educators, e-moderators and students play a role in making video streaming a useful teaching technology. There are advantages to embedding the technology in a social educational context in relation to roles and phases of teaching. In collaboration with educators, instructional developers must learn to see the possibilities of video streaming from the perspective of the instructional process.Denne artikel undersøger videostreaming i forskellige undervisningssituationer med varierende grader af studenteraktivering lige fra forelæsninger til team-baseret læring. Artiklen er et casestudie om implementering af video-streaming på Medicin, Aarhus Universitet. Artiklens mål er at udvikle en model af videostreaming i studenter-centreret undervisning. Forskningsspørgsmålet er: Hvad kendetegner faser i video-streaming i forhold til studentercentreret undervisning? Artiklen udvikler en model med fire faser af videostreaming baseret på et empirisk casestudie og teori om læringsdesign. Artiklen argumenterer for at både undervisere, e-moderatorer og studerende spiller en rolle i forhold til at gøre video-streaming til en nyttig undervisningsteknologi. Selvom universitetsundervisere relativt nemt kan udvikle videoer med sin smartphone eller ved hjælp af et digitalt videokamera, er der fordele ved at indlejre teknologien i en social uddannelsessammenhæng i forhold til roller og faser i undervisningsforløb. Undervisningsudviklere skal i samarbejde med undervisere lære at se mulighederne i video-streaming ud fra et undervisningsforløb

Numerical impacts on tracer transport: A proposed intercomparison test of Atmospheric General Circulation Models

The transport of trace gases by the atmospheric circulation plays an important role in the climate system and its response to external forcing. Transport presents a challenge for Atmospheric General Circulation Models (AGCMs), as errors in both the resolved circulation and the numerical representation of transport processes can bias their abundance. In this study, two tests are proposed to assess transport by the dynamical core of an AGCM. To separate transport from chemistry, the tests focus on the age‐of‐air, an estimate of the mean transport time by the circulation. The tests assess the coupled stratosphere–troposphere system, focusing on transport by the overturning circulation and isentropic mixing in the stratosphere, or Brewer–Dobson Circulation, where transport time‐scales on the order of months to years provide a challenging test of model numerics. Four dynamical cores employing different numerical schemes (finite‐volume, pseudo‐spectral, and spectral‐element) and discretizations (cubed sphere versus latitude–longitude) are compared across a range of resolutions. The subtle momentum balance of the tropical stratosphere is sensitive to model numerics, and the first intercomparison reveals stark differences in tropical stratospheric winds, particularly at high vertical resolution: some cores develop westerly jets and others easterly jets. This leads to substantial spread in transport, biasing the age‐of‐air by up to 25% relative to its climatological mean, making it difficult to assess the impact of the numerical representation of transport processes. This uncertainty is removed by constraining the tropical winds in the second intercomparison test, in a manner akin to specifying the Quasi‐Biennial Oscillation in an AGCM. The dynamical cores exhibit qualitative agreement on the structure of atmospheric transport in the second test, with evidence of convergence as the horizontal and vertical resolution is increased in a given model. Significant quantitative differences remain, however, particularly between models employing spectral versus finite‐volume numerics, even in state‐of‐the‐art cores