Constraining the Origin of Magnetar Flares

Sudden relaxation of the magnetic field in the core of a magnetar produces mechanical energy primarily in the form of shear waves which propagate to the surface and enter the magnetosphere as relativistic Alfv\'en waves. Due to a strong impedance mismatch, shear waves excited in the star suffer many reflections before exiting the star. If mechanical energy is deposited in the core and is converted {\em directly} to radiation upon propagation to the surface, the rise time of the emission is at least seconds to minutes, and probably minutes to hours for a realistic magnetic field geometry, at odds with observed rise times of \lap 10 ms for both and giant flares. Mechanisms for both small and giant flares that rely on the sudden relaxation of the magnetic field of the core are rendered unviable by the impedance mismatch, requiring the energy that drives these events to be stored in the magnetosphere just before the flare. ends, unless the waves are quickly damped.Comment: Final version in Monthly Notices of the Royal Astronomical Society. 13 pages, 5 figure

Model updating using uncertain experimental modal data

The propagation of parameter uncertainty in structural dynamics has become a feasible method to determine the probabilistic description of the vibration response of industrial scale �nite element models. Though methods for uncertainty propagation have been developed extensively, the quanti�cation of parameter uncertainty has been neglected in the past. But a correct assumption for the parameter variability is essential for the estimation of the uncertain vibration response. This paper shows how to identify model parameter means and covariance matrix from uncertain experimental modal test data. The common gradient based approach from deterministic computational model updating was extended by an equation that accounts for the stochastic part. In detail an inverse approach for the identi�cation of statistical parametric properties will be presented which will be applied on a numerical model of a replica of the GARTEUR SM-AG19 benchmark structure. The uncertain eigenfrequencies and mode shapes have been determined in an extensive experimental modal test campaign where the aircraft structure was tested repeatedly while it was 130 times dis- and reassembled in between each experimental modal analysis

Estimates of marginal infrastructure costs for different modes of transport

One component of optimal prices for infrastructure use is the marginal cost of maintaining and operating infrastructure. While extensive studies on optimal congestion and environmental charges as well as the respective cost estimates are available much less attention has been paid to the estimation of marginal infrastructure costs probably due to the assumed lower quantitative importance for pricing compared to environmental and congestion costs. This paper presents results from a set of studies on marginal infrastructure costs for different modes of transport. It is based on research previously undertaken for the European Commission within the UNITE project (Unification of Marginal Costs and Accounts for Transport Efficiency in Europe). The studies employed different methodologies for estimating marginal costs ranging from econometric approaches up to engineering based methods. The focus of the analysis is on road and rail, however, the paper includes also results for an airport and for seaports. The main finding from the methodological point of view is that the "one" ideal methodological approach to estimate marginal infrastructure costs does not exist. Econometric approaches are based on observed behaviour of costs and cost drivers. It is obvious that the actual or observed costs do not always follow technical needs resulting from the use of infrastructure, i.e. do not necessarily reflect true marginal costs. In comparison, marginal costs derived with engineering-based methods are built on measured technical relationships, but which are not necessarily reflected in actual spending. Both econometric and engineering based approaches require a considerable amount of high-quality data with a demanding level of detail so that under this aspect one cannot express a preference for one of the two. The experience with econometric approaches was that in absence of data on axle-load km (for road and rail) the inclusion of transport performance indicators for different vehicle categories or types of transport as explanatory variables cause serious multicollinearity problems which can only be solved by constructing aggregate indicators with the consequence of restrictions to interpretation of results. Engineering based approaches which use axle-load km face vice versa the problem that marginal costs per axle-load km have to be translated back into marginal costs per vehicle type. The research presented in the paper provides evidence that for rail tracks and road infrastructure it is mainly the cost of maintenance, repair and renewal that vary with traffic volume. For terminal infrastructure such as ports and airports it is staff costs which varies in the short run with traffic. For rail tracks and road infrastructure the main cost drivers identified are traffic load, especially measured by weight indicators such as gross-tonne km and axle-load km, infrastructure characteristics such as number of bridges, tunnels, electrification etc., age of infrastructure and maintenance history. For terminal infrastructure where staff costs form the major category of marginal infrastructure costs the traffic load (measured as throughput in ports and as aircraft movements and departing/arriving passengers at airports) is again the main cost driver. In addition, the studies provided evidence that the season, the weekday and the salaries' arrangement have to be considered for analysing operation costs of terminal infrastructure. Both the econometric and the engineering based approaches mostly provided results which are consistent with the u-shaped marginal cost curve suggested by neoclassical economic theory. However, in many cases the detected non-linearities were rather weak in the relevant range of traffic variables. No uniform result was obtained with respect to the question which branch of the "u" describes marginal infrastructure cost behaviour. The quantitative results of the studies are widespread and indicate the need for further research in the field. This holds also true for airport infrastructure and waterborne infrastructure were so far only few studies are available.

Precision Measurement of sin^2 theta_W at a Reactor

This paper presents a strategy for measuring sin^2 theta_W to ~1% at a reactor-based experiment, using antineutrinos electron elastic scattering. This error is comparable to the NuTeV, SLAC E158, and APV results on sin^2 theta_W, but with substantially different contributions to the systematics. An improved method for identifying antineutrino proton events, which serve both as a background and as a normalization sample, is described. The measurement can be performed using the near detector of the presently proposed reactor-based oscillation experiments. We conclude that an absolute error of delta(sin^2 theta_W)=0.0019 may be achieved.Comment: To be Submitted to Phys. Rev.