Structure and fault rock sequences of the Moonlight Fault Zone, West Otago: constraints on fault reactivation during basin inversion

Large normal faults are often reactivated as high-angle reverse faults during compressional basin inversion. Although a common situation worldwide, basin inversion is poorly understood from a mechanical perspective, as high-angle reverse faults are severely misoriented for reactivation (frictional ‘lock-up’ should occur at dips of c. 60°). Prevailing models of failure on high-angle reverse faults rely on fluid overpressure, however such models are calculated on the assumption of Byerlee-type friction (friction coefficient of 0.6 – 0.85). The Moonlight Fault Zone in New Zealand, is a >200 km long Oligocene basin-bounding normal fault that reactivated in the Miocene as a high-angle reverse fault during basin inversion (present dip angle 65°-77°). Excellent exposures of the fault zone exhumed from c. 4-10 km depth are found in creek sections along the entire strike length. This thesis presents field and microstructural observations concerning the structure and fault rock assemblages found in five creek sections within the MFZ, and aims to provide some of the first observational constraints on the structure and possible mechanical properties of reactivated normal faults. In the MFZ wall rocks are mainly quartz-albite-muscovite-chlorite schists with a strong foliation that is everywhere sub-parallel to the Moonlight Fault (i.e. dip angle 65°-75°), with deformation varying in response to host rock composition. Where the hanging wall consists of well foliated, intact greenschist or quartzofeldspathic gneiss, pseudotachylyte is present lying largely sub-parallel to the foliation. Where the hanging wall consists of fissile greyschist it is host to foliation-parallel fault breccias. The footwall is mainly greyschist where fault movements resulted in the formation of meso to macro scale folds whose fold axial planes lie parallel to the orientation of the Moonlight Fault. Where folding has not accommodated all reverse-slip, Moonlight Fault-parallel breccias are present. Although the overall structure of the fault zone changes significantly along strike in response to wall rock composition, the fault core always contains interconnected layers of foliated cataclasite or gouge rich in authigenically-grown chlorite and muscovite which is regionally significant and, critically, interconnected on a regional scale. The fault core is regularly flanked by a zone of breccia which at times shows a strain transition into the <5 metre thick fault core. Microstructural evidence suggests deformation in the fault core was accommodated by a combination of cataclasis, frictional slip along phyllosilicate seams and dissolution-precipitation. Published frictional strength measurements for chlorite and muscovite (friction coefficient of 0.32-0.38) are used to explore mechanical models of frictional reactivation along high-angle reverse faults. Results show that low-friction fault cores increase the frictional lock-up angle to 71°, allowing for easier reactivation of faults that initially formed at 60°. These results indicate that low frictional strength may play an important role in slip on high-angle reverse faults during basin inversion

A Theory of Structural Change That Can Fit the Data

We study structural change in historical consumption expenditure of theUnited States, the United Kingdom, Canada, and Australia over morethan a century. We characterize the most general class of preferencesin a time-additive setting that admits aggregation of the saving deci-sion and allows to identify preference parameters from aggregate data.We parametrize and estimate such intertemporally aggregable (IA) pref-erences and discuss their properties in a dynamic general equilibriumframework with sustained growth. Our preference class is considerablymore flexible than the Gorman form or PIGL, giving rise to a good fit ofthe non-monotonic pattern of structural change

Fluid/solid transition in a hard-core system

We prove that a system of particles in the plane, interacting only with a certain hard-core constraint, undergoes a fluid/solid phase transition

Wie beurteilen Sozialarbeitende ihre Beratungskompetenz?

Ein an der BFH entwickeltes Inventar zur Beratungskompetenz in der Sozialen Arbeit beruht auf der Selbstbeurteilung von Fachpersonen. Es gliedert die Beratungskompetenz in fünf Dimensionen. Mit Hilfe eines Online-Instruments können Sozialarbeitende nun ihre Stärken und Schwächen ermitteln

Gewässeranschluss erosionsgefährdeter Flächen

Offsite-Schäden durch Bodenerosion, insbesondere die Gewässerbelastung, haben in der Erosionsforschung deutlich an Relevanz gewonnen. Damit man umweltwirksam und kosteneffizient Verminderungsmaßnahmen ergreifen kann, müssen gezielt die Flächen, die sowohl ein hohes Erosionsrisiko als auch einen Gewässeranschluss haben, identifiziert werden. Es wird ein einfaches Risikoab-schätzungstool präsentiert, welches die Ausscheidung von potentiell beitragenden Flächen (critical source areas) bezüglich Sedimenteintrag in die Gewässer der Schweiz ermöglicht

Optimized broad-histogram simulations for strong first-order phase transitions: Droplet transitions in the large-Q Potts model

The numerical simulation of strongly first-order phase transitions has remained a notoriously difficult problem even for classical systems due to the exponentially suppressed (thermal) equilibration in the vicinity of such a transition. In the absence of efficient update techniques, a common approach to improve equilibration in Monte Carlo simulations is to broaden the sampled statistical ensemble beyond the bimodal distribution of the canonical ensemble. Here we show how a recently developed feedback algorithm can systematically optimize such broad-histogram ensembles and significantly speed up equilibration in comparison with other extended ensemble techniques such as flat-histogram, multicanonical or Wang-Landau sampling. As a prototypical example of a strong first-order transition we simulate the two-dimensional Potts model with up to Q=250 different states on large systems. The optimized histogram develops a distinct multipeak structure, thereby resolving entropic barriers and their associated phase transitions in the phase coexistence region such as droplet nucleation and annihilation or droplet-strip transitions for systems with periodic boundary conditions. We characterize the efficiency of the optimized histogram sampling by measuring round-trip times tau(N,Q) across the phase transition for samples of size N spins. While we find power-law scaling of tau vs. N for small Q \lesssim 50 and N \lesssim 40^2, we observe a crossover to exponential scaling for larger Q. These results demonstrate that despite the ensemble optimization broad-histogram simulations cannot fully eliminate the supercritical slowing down at strongly first-order transitions.Comment: 11 pages, 12 figure

Dynamics of the Wang-Landau algorithm and complexity of rare events for the three-dimensional bimodal Ising spin glass

We investigate the performance of flat-histogram methods based on a multicanonical ensemble and the Wang-Landau algorithm for the three-dimensional +/- J spin glass by measuring round-trip times in the energy range between the zero-temperature ground state and the state of highest energy. Strong sample-to-sample variations are found for fixed system size and the distribution of round-trip times follows a fat-tailed Frechet extremal value distribution. Rare events in the fat tails of these distributions corresponding to extremely slowly equilibrating spin glass realizations dominate the calculations of statistical averages. While the typical round-trip time scales exponential as expected for this NP-hard problem, we find that the average round-trip time is no longer well-defined for systems with N >= 8^3 spins. We relate the round-trip times for multicanonical sampling to intrinsic properties of the energy landscape and compare with the numerical effort needed by the genetic Cluster-Exact Approximation to calculate the exact ground state energies. For systems with N >= 8^3 spins the simulation of these rare events becomes increasingly hard. For N >= 14^3 there are samples where the Wang-Landau algorithm fails to find the true ground state within reasonable simulation times. We expect similar behavior for other algorithms based on multicanonical sampling.Comment: 9 pages, 12 figure

Status of art of reaction models for projectiles far from stability

This talk will review the status of art of nuclear and Coulomb breakup theories and their relation to optical models of elastic scattering of exotic projectiles. The effect of the final state interactions between the breakup particle and the core and target nuclei will be clarified and some typical numerical calculations for the relevant observables will be presented and compared to experimental data. Finally new results will be shown to demonstrate the feasibility of a novel type of experiment involving heavy projectiles far from stability on heavy targets.Comment: 10 pages, 4 figures. Proceedings of NN2007, Rio de Janeir

Feedback-optimized parallel tempering Monte Carlo

We introduce an algorithm to systematically improve the efficiency of parallel tempering Monte Carlo simulations by optimizing the simulated temperature set. Our approach is closely related to a recently introduced adaptive algorithm that optimizes the simulated statistical ensemble in generalized broad-histogram Monte Carlo simulations. Conventionally, a temperature set is chosen in such a way that the acceptance rates for replica swaps between adjacent temperatures are independent of the temperature and large enough to ensure frequent swaps. In this paper, we show that by choosing the temperatures with a modified version of the optimized ensemble feedback method we can minimize the round-trip times between the lowest and highest temperatures which effectively increases the efficiency of the parallel tempering algorithm. In particular, the density of temperatures in the optimized temperature set increases at the "bottlenecks'' of the simulation, such as phase transitions. In turn, the acceptance rates are now temperature dependent in the optimized temperature ensemble. We illustrate the feedback-optimized parallel tempering algorithm by studying the two-dimensional Ising ferromagnet and the two-dimensional fully-frustrated Ising model, and briefly discuss possible feedback schemes for systems that require configurational averages, such as spin glasses.Comment: 12 pages, 14 figure

Facilitating the analysis of a UK national blood service supply chain using distributed simulation

In an attempt to investigate blood unit ordering policies, researchers have created a discrete-event model of the UK National Blood Service (NBS) supply chain in the Southampton area of the UK. The model has been created using Simul8, a commercial-off-the-shelf discrete-event simulation package (CSP). However, as more hospitals were added to the model, it was discovered that the length of time needed to perform a single simulation severely increased. It has been claimed that distributed simulation, a technique that uses the resources of many computers to execute a simulation model, can reduce simulation runtime. Further, an emerging standardized approach exists that supports distributed simulation with CSPs. These CSP Interoperability (CSPI) standards are compatible with the IEEE 1516 standard The High Level Architecture, the defacto interoperability standard for distributed simulation. To investigate if distributed simulation can reduce the execution time of NBS supply chain simulation, this paper presents experiences of creating a distributed version of the CSP Simul8 according to the CSPI/HLA standards. It shows that the distributed version of the simulation does indeed run faster when the model reaches a certain size. Further, we argue that understanding the relationship of model features is key to performance. This is illustrated by experimentation with two different protocols implementations (using Time Advance Request (TAR) and Next Event Request (NER)). Our contribution is therefore the demonstration that distributed simulation is a useful technique in the timely execution of supply chains of this type and that careful analysis of model features can further increase performance