Does the mass distribution in discs influence encounter-induced losses in young star clusters?

One mechanism for the external destruction of protoplanetary discs in young dense clusters is tidal disruption during the flyby of another cluster member. The degree of mass loss in such an encounter depends, among other parameters, on the distribution of the material within the disc. Previous work showed that this is especially so in encounters that truncate large parts of the outer disc. The expectation is that the number of completely destroyed discs in a cluster depends also on the mass distribution within the discs. Here we test this hypothesis by determining the influence of encounters on the disc fraction and average disc mass in clusters of various stellar densities for different mass distributions in the discs. This is done by performing Nbody6 simulation of a variety of cluster environments, where we track the encounter dynamics and determine the mass loss due to these encounters for different disc-mass distributions. We find that although the disc mass distribution has a significant impact on the disc losses for specific star-disc encounters, the overall disc frequency generally remains rather unaffected. The reason is that in single encounters the dependence on the mass distribution is strongest if both stars have very different masses. Such encounters are rather infrequent in sparse clusters. In dense clusters such encounters are more common, however, here the disc frequency is largely determined by encounters between low-mass stars such that the overall disc frequency does not change significantly. For tidal disruption the disc destruction in clusters is fairly independent of the actual distribution of the material in the disc. The all determining factor remains the cluster density.Comment: 7pages, 4 figures, accepted by A&

Sizes of protoplanetary discs after star-disc encounters

Most stars do not form in isolation, but as part of a star cluster or association. These young stars are initially surrounded by protoplanetary discs. In these cluster environments tidal interactions with other cluster members can alter the disc properties. Besides the disc frequency, its mass, angular momentum, and energy, in particular the disc's size is prone to being changed by a passing star. So far the change in disc size was only investigated for a small number of very specific encounters. Several studies investigated the effect of the cluster environment on the sizes of planetary systems, like our own solar system, based on a generalisation of information from this limited sample. We performed numerical simulations covering the wide parameter space typical for young star clusters, to test the validity of this approach. Here the sizes of discs after encounters are presented, based on a size definition which is comparable to that one used in observational studies. We find that, except for encounters between equal-mass stars, the usually applied estimates are insufficient. They tend to severely overestimate the remaining disc size. We show that the disc size after an encounter can be described by a relatively simple dependence on the periastron distance and the mass ratio of the encounter partners. This knowledge allows, for example, to pin down the types of encounter possibly responsible for the structure of today's solar system.Comment: 7 pages, 4 figures, + 2 pages Online material, accepted by A&

Child and adolescent psychiatric disorders in a public service over seventy years

The entire sample of N=45554 patients attending the child and adolescent psychiatric service of the Canton of Zurich, Switzerland between 1921 and 1990 was analyzed with regard to age, sex, and diagnoses. Data were based on annual reports of the institution for the period between 1921 and 1978. From 1979 onwards, electronically stored data on each patient were available. ICD-9 diagnoses were applied between 1979 and 1987. The ICD-10 system was introduced in 1988. The total administrative prevalence rate varied between 0.15 and 0.40 percent with an increasing trend over time. On the average, boys outnumbered girls by a sex ratio of 2:1. The age distribution showed peaks at 8 to 9 years and during adolescence. The distributions of the most common diagnoses showed remarkable differences over time. It is assumed that changes in diagnostic categories rather than changes in true prevalence rates play a major role in the latter tren

Applications of the electric potential sensor for healthcare and assistive technologies

The work discussed in this thesis explores the possibility of employing the Electric Potential Sensor for use in healthcare and assistive technology applications with the same and in some cases better degrees of accuracy than those of conventional technologies. The Electric Potential Sensor is a generic and versatile sensing technology capable of working in both contact and non-contact (remote) modes. New versions of the active sensor were developed for specific surface electrophysiological signal measurements. The requirements in terms of frequency range, electrode size and gain varied with the type of signal measured for each application. Real-time applications based on electrooculography, electroretinography and electromyography are discussed, as well as an application based on human movement. A three sensor electrooculography eye tracking system was developed which is of interest to eye controlled assistive technologies. The system described achieved an accuracy at least as good as conventional wet gel electrodes for both horizontal and vertical eye movements. Surface recording of the electroretinogram, used to monitor eye health and diagnose degenerative diseases of the retina, was achieved and correlated with both corneal fibre and wet gel surface electrodes. The main signal components of electromyography lie in a higher bandwidth and surface signals of the deltoid muscle were recorded over the course of rehabilitation of a subject with an injured arm. Surface electromyography signals of the bicep were also recorded and correlated with the joint dynamics of the elbow. A related non-contact application of interest to assistive technologies was also developed. Hand movement within a defined area was mapped and used to control a mouse cursor and a predictive text interface

Probabilistic flood loss modelling for residential buildings

Hochwasser stellt ein großes Risiko für Wohngebäude in Europa dar, und es wird erwartet, dass das Risiko in der Zukunft aufgrund klimatischer und sozioökonomischer Veränderungen zunehmen wird. Aktuelle Hochwasserrisikomodelle basieren meist auf einfachen Wasserstands-Schadenskurven. Diese Ansätze vereinfachen die Hochwasserschadensprozesse stark, können ungenau sein und bergen große Unsicherheiten, die oft nicht quantifiziert. Die Doktorarbeit stellt die Integration neuer Daten in probabilistische, multivariable Schadensmodelle zur Verbesserung ihrer Übertragbarkeit vor. Diese neuen Datenquellen und Modellierungsansätze werden verwendet, um zukünftige Veränderung des Hochwasserrisikos für Wohngebäude in Europa abzuschätzen und Risikokomponenten zu analysieren. Die Arbeit zeigt, OpenStreetMap (OSM) Daten liefern nützliche Informationen für die Modellierung von Hochwasserschäden und ermöglichen Modelltransfers. Die Integration von aus OSM abgeleiteten Gebäudeeigenschaften und Hochwassererfahrung aus Ereignisdatenbanken in das Bayes’sche Netzwerk basierte Hochwasserschadensmodelle für den privaten Sektor (BN-FLEMOps) ermöglichte die Implementierung auf der Mesoskala. Durch Vergleiche von Schadensschätzungen mit beobachteten Schäden in mehreren Fallstudien in Europa wurde das Modell validiert und detailliert mit einem Ensemble aus 20 Schadensmodellen verglichen. In einer abschließenden Studie werden die zukünftigen Veränderungen des Risikos für Wohngebäude in Europa modelliert. Die erwarteten jährlichen Schäden bis zum Ende des 21. Jahrhunderts werden um das 10-fache ansteigen. Die Britischen Inseln und der größte Teil von Zentral-Europa müssen mit einer starken Risikozunahme rechnen. Teile Skandinaviens und des Mittelmeerraums werden dagegen ein stagnierendes oder abnehmendes Hochwasserrisiko verzeichnen. Eine Verbesserung der privaten Vorsorgemaßnahmen könnte das Hochwasserrisiko im Mittel um 15 % und in einigen europäischen Regionen um bis zu 20 % verringern.Flooding poses great risks for residential buildings in Europe and is expected to increase in the future, driven by climatic and socio-economic change. Current flood risk models rely mostly on simple stage-damage curves for flood loss estimation. This approach oversimplifies flood damage processes, can be inaccurate and harbour large uncertainties that often are not quantified and transparently communicated. This thesis presents research that integrates new data sources into probabilistic, multi-variable loss models to improve their transferability. These new data sources and approaches are used to estimate future fluvial flood risk change for residential buildings in Europe. Contributions of the three risk components, hazard, exposure, and vulnerability are analysed and compared independently and in combination. OpenStreetMap (OSM) data are identified as a valuable source of information for flood loss modelling and enables model transfers while retaining high predictive performance. Integrating OSM derived building characteristics and flood experience information from flood event databases into the Bayesian Network Flood Loss Estimation MOdel for the private sector (BN-FLEMOps) enables the spatio-temporal and scale transformation of the model. The model is validated with reported losses in multiple case studies in Europe and compared in detail with a model ensemble of 20 internationally published flood loss models. In a final study, the future flood risk changes for residential buildings in Europe are modelled. The expected annual damage will increase up to 10-fold until the end of the 21st century. Most of Central Europe and the British Isles have to expect strong risk increases. Parts of Scandinavia and the Mediterranean on the other hand will see stagnating or decreasing fluvial flood risk. Improving private precaution could reduce flood risk by 15 % on average and up to 20 % in some European regions