FISH: A 3D parallel MHD code for astrophysical applications

FISH is a fast and simple ideal magneto-hydrodynamics code that scales to ~10 000 processes for a Cartesian computational domain of ~1000^3 cells. The simplicity of FISH has been achieved by the rigorous application of the operator splitting technique, while second order accuracy is maintained by the symmetric ordering of the operators. Between directional sweeps, the three-dimensional data is rotated in memory so that the sweep is always performed in a cache-efficient way along the direction of contiguous memory. Hence, the code only requires a one-dimensional description of the conservation equations to be solved. This approach also enable an elegant novel parallelisation of the code that is based on persistent communications with MPI for cubic domain decomposition on machines with distributed memory. This scheme is then combined with an additional OpenMP parallelisation of different sweeps that can take advantage of clusters of shared memory. We document the detailed implementation of a second order TVD advection scheme based on flux reconstruction. The magnetic fields are evolved by a constrained transport scheme. We show that the subtraction of a simple estimate of the hydrostatic gradient from the total gradients can significantly reduce the dissipation of the advection scheme in simulations of gravitationally bound hydrostatic objects. Through its simplicity and efficiency, FISH is as well-suited for hydrodynamics classes as for large-scale astrophysical simulations on high-performance computer clusters. In preparation for the release of a public version, we demonstrate the performance of FISH in a suite of astrophysically orientated test cases.Comment: 27 pages, 11 figure

Schnittstelle Notaufnahme: Interdisziplinäre Perspektiven

Zusammenfassung: Die Notaufnahme des Basler Universitätsspitals wird interdisziplinär als "Notfallstation" geführt. Das dort praktizierte "Basler Modell" wird schlaglichtartig beleuchtet. Ethische Fragestellungen, insbesondere die Frage nach dem Sistieren einer Behandlung, sollten frühzeitig und interdisziplinär besprochen werden. Da das Ziel der Versorgung in der präklinischen Phase zumeist der möglichst rasche Transport in ein geeignetes Zielkrankenhaus ist, bietet sich oft erst im Reanimationsraum der Notfallstation erstmals die Chance, diese Fragen überhaupt auszusprechen. Hier können entscheidungsrelevante Zusatzinformationen berücksichtigt werden wie etwa der mutmaßliche Wille des Patienten, aber auch die Prognose. Die unterschiedlichen Standards der präklinischen und der klinischen Phase können an der Schnittstelle Notfallstation zu Konflikten führen. Hier ist die Kommunikation des Teamleaders mit dem Rettungsteam, aber auch mit den Kollegen der anderen Disziplinen von entscheidender Bedeutun

Incidence of Reinfections with Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae in Pig Farms Located in Respiratory-Disease-Free Regions of Switzerland – Identification and Quantification of Risk Factors

The objective of the study was to identify risk factors for reintroduction of Actinobacillus pleuopneumoniae and Mycoplasma hyopneumoniae (enzootic pneumonia) onto pig farms in areas in Switzerland that were involved in an eradication programme from 1996 to 1999 and to assess the role of dealers in relation to these reinfections. The study was based on the comparison of pig farms that were reinfected in the year 2000 (cases) and pig farms that remained uninfected in the same area (controls). Additionally, data were collected from Swiss pig dealers and transport companies. Out of a total of 3983 farms, 107 farms were reinfected in the year 2000. The incidences were 0.1% for Actinobacillus pleuopneumoniae and 2.6% for Mycoplasma hyopneumoniae (enzootic pneumonia). Compared to reinfection rates prior to the eradication programme, this is a considerable reduction. Statistically significant risk factors for the reinfection were 'finishing farm', 'large mixed breeding-finishing farm', 'reinfected neighbour' and 'parking site for pig transport vehicles close to the farm'. Pig farmers that purchased pigs from only one supplier per batch had a lower risk of reintroducing infection (protective factor). As long as infected and uninfected regions co-exist in Switzerland, direct and indirect contact between farms, pig herds and slaughter sites via transport vehicles are a major pathway of disease spread. Risk management measures linked to these contacts are therefore of key importance. The survey of dealers indicated various areas for improvement such as strategic planning of pick-up routes or cleaning and disinfecting of trucks

Can skills assessment on a virtual reality trainer predict a surgical trainee's talent in laparoscopic surgery?

Background: A number of studies have investigated several aspects of feasibility and validity of performance assessments with virtual reality surgical simulators. However, the validity of performance assessments is limited by the reliability of such measurements, and some issues of reliability still need to be addressed. This study aimed to evaluate the hypothesis that test subjects show logarithmic performance curves on repetitive trials for a component task of laparoscopic cholecystectomy on a virtual reality simulator, and that interindividual differences in performance after considerable training are significant. According to kinesiologic theory, logarithmic performance curves are expected and an individual's learning capacity for a specific task can be extrapolated, allowing quantification of a person's innate ability to develop task-specific skills. Methods: In this study, 20 medical students at the University of Basel Medical School performed five trials of a standardized task on the LS 500 virtual reality simulator for laparoscopic surgery. Task completion time, number of errors, economy of instrument movements, and maximum speed of instrument movements were measured. Results: The hypothesis was confirmed by the fact that the performance curves for some of the simulator measurements were very close to logarithmic curves, and there were significant interindividual differences in performance at the end of the repetitive trials. Conclusions: Assessment of perceptual motor skills and the innate ability of an individual with no prior experience in laparoscopic surgery to develop such skills using the LS 500 VR surgical simulator is feasible and reliabl

Evolutionary Trends in the Physciaceae

The current delimitation of the family Physciaceae has been generally accepted since detailed descriptions of ascus characters allowed for a more natural circumscription of lichenized ascomycetes. The generic relations within the family are, however, still controversial and depend on the importance different authors attribute to specific morphological or chemical characteristics. The aim of this paper is to describe ascospore ontogeny and to test the present taxonomic structure of the family against a parsimony-based cladistic analysis, which includes three different scenarios of a priori character weighting. A study of ascospore ontogeny revealed two distinct developmental lines. One line revealed a delayed septum formation, which clearly showed transitions from spores with apical and median thickenings to spores without apical, but still well developed median thickenings, and to spores without any thickenings. In the second developmental line with an early septum formation again taxa with no thickenings, median thickenings, and both median and apical thickenings were found. Although these characters were constant at a species level, median wall thickenings especially varied among otherwise closely related taxa. In the cladistic analyses the current taxonomic structure of the Physciaceae was only obtained after the five character groups, namely morphology and anatomy of the vegetative thallus, conidiomata and conidia, morphology and anatomy of the apothecia, ontogeny of the ascospores, and secondary metabolites of the thallus, were given equal importance, and after a subjective a priori weighting further increased the weight of the three characters ‘conidial shape', ‘presence of apical thickenings', and ‘spore septation delayed'. This structure was not supported by a cladistic analysis with equally weighted characters but reflected the biased character weighting of the present day Physdaceae taxonomy. The taxonomic importance of conidial characters and of anatomical and ontogenetical spore characteristics need, therefore, a careful reconsideration in futur

Breakdown of Kolmogorov scaling in models of cluster aggregation with deposition

The steady state of the model of cluster aggregation with deposition is characterized by a constant flux of mass directed from small masses towards large masses. It can therefore be studied using phenomenological theories of turbulence, such as Kolmogorov's 1941 theory. On the other hand, the large scale behavior of the aggregation model in dimensions lower than or equal to two is governed by a perturbative fixed point of the renormalization group flow, which enables an analytic study of the scaling properties of correlation functions in the steady state. In this paper, we show that the correlation functions have multifractal scaling, which violates linear Kolmogorov scaling. The analytical results are verified by Monte Carlo simulations.Comment: 5 pages 4 figure

Noether-Lefschetz theory and the Yau-Zaslow conjecture

The Yau-Zaslow conjecture determines the reduced genus 0 Gromov-Witten invariants of K3 surfaces in terms of the Dedekind eta function. Classical intersections of curves in the moduli of K3 surfaces with Noether-Lefschetz divisors are related to 3-fold Gromov-Witten theory via the K3 invariants. Results by Borcherds and Kudla-Millson determine the classical intersections in terms of vector-valued modular forms. Proven mirror transformations can often be used to calculate the 3-fold invariants which arise. Via a detailed study of the STU model (determining special curves in the moduli of K3 surfaces), we prove the Yau-Zaslow conjecture for all curve classes on K3 surfaces. Two modular form identities are required. The first, the Klemm-Lerche-Mayr identity relating hypergeometric series to modular forms after mirror transformation, is proven here. The second, the Harvey-Moore identity, is proven by D. Zagier and presented in the paper.Comment: 40 page

Copper flows in buildings, infrastructure and mobiles: a dynamic model and its application to Switzerland

During the last century, the consumption of materials for human needs increased by several orders of magnitude, even for non-renewable materials such as metals. Some data on annual consumption (input) and recycling/waste (output) can often be found in the federal statistics, but a clear picture of the main flows is missing. A dynamic material flow model is developed for the example of copper in Switzerland in order to simulate the relevant copper flows and stocks over the last 150years. The model is calibrated using data from statistical and published sources as well as from interviews and measurements. A simulation of the current state (2000) is compared with data from other studies. The results show that Swiss consumption and losses are both high, at a level of about 8 and 2kg/(capyear), respectively, or about three times higher than the world average. The model gives an understanding of the flows and stocks and their interdependencies as a function of time. This is crucial for materials whose consumption dynamics are characterised by long lifetimes and hence for relating the current output to the input of the whole past. The model allows a comprehensive discussion of possible measures to reduce resource use and losses to the environment. While increasing the recycling reduces losses to landfill, only copper substitution can reduce the different losses to the environment, although with a time delay of the order of a lifetim