The grain-scale distribution and behaviour of melt and fluid in crystalline analogue systems

The production, segregation and migration of melt and aqueous fluids (henceforth called liquid) plays an important role for the transport of mass and energy within the mantle and the crust of the Earth. Many properties of large-scale liquid migration processes such as the permeability of a rock matrix or the initial segregation of newly formed liquid from the host-rock depends on the grain-scale distribution and behaviour of liquid. Although the general mechanisms of liquid distribution at the grain-scale are well understood, the influence of possibly important modifying processes such as static recrystallization, deformation, and chemical disequilibrium on the liquid distribution is not well constrained. For this thesis analogue experiments were used that allowed to investigate the interplay of these different mechanisms in-situ. In high-temperature environments where melts are produced, the grain-scale distribution in “equilibrium” is fully determined by the liquid fraction and the ratio between the solid-solid and the solid-liquid surface energy. The latter is commonly expressed as the dihedral or wetting angle between two grains and the liquid phase (Chapter 2). The interplay of this “equilibrium” liquid distribution with ongoing surface energy driven recrystallization is investigated in Chapter 4 and 5 with experiments using norcamphor plus ethanol liquid. Ethanol in contact with norcamphor forms a wetting angle of about 25°, which is similar to reported angles of rock-forming minerals in contact with silicate melt. The experiments in Chapter 4 show that previously reported disequilibrium features such as trapped liquid lenses, fully-wetted grain boundaries, and large liquid pockets can be explained by the interplay of the liquid with ongoing recrystallization. Closer inspection of dihedral angles in Chapter 5 reveals that the wetting angles are themselves modified by grain coarsening. Ongoing recrystallization constantly moves liquid-filled triple junctions, thereby altering the wetting angles dynamically as a function of the triple junction velocity. A polycrystalline aggregate will therefore always display a range of equilibrium and dynamic wetting angles at raised temperature, rather than a single wetting angle as previously thought. For the deformation experiments partially molten KNO3–LiNO3 experiments were used in addition to norcamphor–ethanol experiments (Chapter 6). Three deformation regimes were observed. At a high bulk liquid fraction >10 vol.% the aggregate deformed by compaction and granular flow. At a “moderate” liquid fraction, the aggregate deformed mainly by grain boundary sliding (GBS) that was localized into conjugate shear zones. At a low liquid fraction, the grains of the aggregate formed a supporting framework that deformed internally by crystal plastic deformation or diffusion creep. Liquid segregation was most efficient during framework deformation, while GBS lead to slow liquid segregation or even liquid dispersion in the deforming areas.

(De)colonization through topophilia: Marjorie Kinnan Rawlings’s life and work in Florida

(De)colonization Through Topophilia: Marjorie Kinnan Rawlings’s Life and Work in Florida attempts to reveal the author’s intimate connection to and mental growth through her place, namely the Cross Creek environs, and its subsequent effect on her writing. In 1928, Marjorie Kinnan Rawlings and her first husband Charles Rawlings came to Cross Creek, Florida. They bought the shabby farmhouse on Cross Creek Road, trying to be both, writers and farmers. However, while Charles Rawlings was unable to write in the backwoods of the Florida Interior, Rawlings found her literary voice and entered a symbiotic, reciprocal relationship with the natural world of the Cracker frontier. Her biographical preconditions – a childhood spent in the rural area of Rock Creek, outside of Washington D. C. - and a father who had instilled in her a sense of place or topophilia, enabled her to overcome severe marriage tensions and the hostile climate women writers faced during the Depression era. Nature as a helping ally and as an “undomesticated”(1) space/place is a recurrent motif throughout most of Rawlings’s Florida literature. At a time when writing the American landscape/documentary and the extraction of the self from texts was the prevalent literary genre, Marjorie Kinnan Rawlings inscribed herself into her texts. However, she knew that the American public was not yet ready for a ‘feminist revolt’, but was receptive of the longtime ‘inaudible’ voices from America’s regions, especially with regard to urban poverty and a homeward yearning during the Depression years. Fusing with the dynamic eco-consciousness of her Cracker friends and neighbors, Rawlings wrote in the literary category of regionalism enabling her to pursue three of her major aims: an individuated self, a self that assimilated with the ‘master narratives’ of her time and the recognition of the Florida Cracker and Scrub region. The first part of this dissertation briefly introduces the largely unknown and underestimated writer Marjorie Kinnan Rawlings, providing background information on her younger years, the relationship toward her family and other influential persons in her life. Furthermore, it takes a closer look at the literary category of regionalism and Rawlings’s use of ‘place’ in her writings. The second part is concerned with the ‘region’ itself, the state of Florida. It focuses on the natural peculiarities of the state’s Interior, the scrub and hammock land around her Cracker hamlet as well as the unique culture of the Florida Cracker. Part IV is concerned with the analysis of her four Florida books. The author is still widely related to the ever-popular novel The Yearling (1938). South Moon Under (1933) and Golden Apples (1935), her first two novels, have not been frequently republished and have subsequently fallen into oblivion. Cross Creek (1942), Rawlings’s last Florida book, however, has recently gained renewed popularity through its use in classes on nature writers and the non-fiction essay but it requires and is here re-evaluated as the author’s (relational) autobiography. The analysis through place is brought to completion in this work and seems to intentionally close the circle of Rawlings’s Florida writings. It exemplifies once more that detachment from place is impossible for Rawlings and that the intermingling of life and place in literature, is essential for the (re)creation of her identity. Cross Creek is therefore not only one of Rawlings’s greatest achievements; it is more importantly the key to understanding the author’s self and her fiction. Through the ‘natural’ interrelationship of place and self and by looking “mutually outward and inward,”(2) Marjorie Kinnan Rawlings finds her literary voice, a home and ‘a room of her own’ in which to write and come to consciousness. Her Florida literature is not only product but also medium and process in her assessment of her identity and self. _____________ (1) Alaimo, Stacy. Undomesticated Ground: Recasting Nature as Feminist Space (Ithaca: Cornell UP, 2000) 23. (2) Libby, Brooke. “Nature Writing as Refuge: Autobiography in the Natural World” Reading Under the Sign of Nature. New Essays in Ecocriticism. Ed. John Tallmadge and Henry Harrington. (Salt Lake City: The U of Utah P, 2000) 200.

Structural and strain analysis in the Late Paleozoic coastal accretionary wedge of central Chile

Abstract In this study structural and finite strain data are used to explore the tectonic evolution and the exhumation history of the Chilean accretionary wedge. The Chilean accretionary wedge is part of a Late Paleozoic subduction complex that developed during subduction of the Pacific plate underneath South America. The wedge is commonly subdivided into a structurally lower Western Series and an upper Eastern Series. This study shows the progressive development of structures and finite strain from the least deformed rocks in the eastern part of the Eastern Series of the accretionary wedge to higher grade schist of the Western Series at the Pacific coast. Furthermore, this study reports finite-strain data to quantify the contribution of vertical ductile shortening to exhumation. Vertical ductile shortening is, together with erosion and normal faulting, a process that can aid the exhumation of high-pressure rocks. In the east, structures are characterized by upright chevron folds of sedimentary layering which are associated with a penetrative axial-plane foliation, S1. As the F1 folds became slightly overturned to the west, S1 was folded about recumbent open F2 folds and an S2 axial-plane foliation developed. Near the contact between the Western and Eastern Series S2 represents a prominent subhorizontal transposition foliation. Towards the structural deepest units in the west the transposition foliation became progressively flat lying. Finite-strain data as obtained by Rf/Phi and PDS analysis in metagreywacke and X-ray texture goniometry in phyllosilicate-rich rocks show a smooth and gradual increase in strain magnitude from east to west. There are no evidences for normal faulting or significant structural breaks across the contact of Eastern and Western Series. The progressive structural and strain evolution between both series can be interpreted to reflect a continuous change in the mode of accretion in the subduction wedge. Before ~320-290 Ma the rocks of the Eastern Series were frontally accreted to the Andean margin. Frontal accretion caused horizontal shortening and upright folds and axial-plane foliations developed. At ~320-290 Ma the mode of accretion changed and the rocks of the Western Series were underplated below the Andean margin. This basal accretion caused a major change in the flow field within the wedge and gave rise to vertical shortening and the development of the penetrative subhorizontal transposition foliation. To estimate the amount that vertical ductile shortening contributed to the exhumation of both units finite strain is measured. The tensor average of absolute finite strain yield Sx=1.24, Sy=0.82 and Sz=0.57 implying an average vertical shortening of ca. 43%, which was compensated by volume loss. The finite strain data of the PDS measurements allow to calculate an average volume loss of 41%. A mass balance approximates that most of the solved material stays in the wedge and is precipitated in quartz veins. The average of relative finite strain is Sx=1.65, Sy=0.89 and Sz=0.59 indicating greater vertical shortening in the structurally deeper units. A simple model which integrates velocity gradients along a vertical flow path with a steady-state wedge is used to estimate the contribution of deformation to ductile thinning of the overburden during exhumation. The results show that vertical ductile shortening contributed 15-20% to exhumation. As no large-scale normal faults have been mapped the remaining 80-85% of exhumation must be due to erosion.

Measurement of the oscillation frequency of B s mesons in the hadronic decay mode B s pi D s (phi pi) X with the D0 detector at the Fermilab Tevatron collider

The standard model (SM) of particle physics is a theory, describing three out of four fundamental forces. In this model the Cabibbo-Kobayashi-Maskawa (CKM) matrix describes the transformation between the mass and weak eigenstates of quarks. The matrix properties can be visualized as triangles in the complex plane. A precise measurement of all triangle parameters can be used to verify the validity of the SM. The least precisely measured parameter of the triangle is related to the CKM element |Vtd|, accessible through the mixing frequency (oscillation) of neutral B mesons, where mixing is the transition of a neutral meson into its anti-particle and vice versa. It is possible to calculate the CKM element |Vtd| and a related element |Vts| by measuring the mass differences Dmd (Dms ) between neutral Bd and bar{Bd} (Bs and bar{Bs}) meson mass eigenstates. This measurement is accomplished by tagging the initial and final state of decaying B mesons and determining their lifetime. Currently the Fermilab Tevatron Collider (providing pbar{p} collisions at sqrt{s}=1.96 TeV) is the only place, where Bs oscillations can be studied. The first selection of the "golden", fully hadronic decay mode Bs->Ds pi(phi pi)X at DØ is presented in this thesis. All data, taken between April 2002 and August 2007 with the DØ detector, corresponding to an integrated luminosity of int{L}dt=2.8/fb is used. The oscillation frequency Dms and the ratio |Vtd|/|Vts| are determined as Dms = (16.6 +0.5-0.4(stat) +0.4-0.3(sys)) 1/ps, |Vtd|/|Vts| = 0.213 +0.004-0.003(exp)pm 0.008(theor). These results are consistent with the standard model expectations and no evidence for new physics is observable.

Quantifying and modeling financial market fluctuations

Die Entstehung eines Marktpreises für einen Vermögenswert kann als Superposition der einzelnen Aktionen der Marktteilnehmer aufgefasst werden, die damit kumulativ Angebot und Nachfrage erzeugen. Dies ist in der statistischen Physik mit der Entstehung makroskopischer Eigenschaften vergleichbar, die von mikroskopischen Wechselwirkungen zwischen den beteiligten Systemkomponenten hervorgerufen werden. Die Verteilung der Preisänderungen an Finanzmärkten unterscheidet sich deutlich von einer Gaußverteilung. Dies führt zu empirischen Besonderheiten des Preisprozesses, zu denen neben dem Skalierungsverhalten nicht-triviale Korrelationsfunktionen und zeitlich gehäufte Volatilität zählen. In der vorliegenden Arbeit liegt der Fokus auf der Analyse von Finanzmarktzeitreihen und den darin enthaltenen Korrelationen. Es wird ein neues Verfahren zur Quantifizierung von Muster-basierten komplexen Korrelationen einer Zeitreihe entwickelt. Mit dieser Methodik werden signifikante Anzeichen dafür gefunden, dass sich typische Verhaltensmuster von Finanzmarktteilnehmern auf kurzen Zeitskalen manifestieren, dass also die Reaktion auf einen gegebenen Preisverlauf nicht rein zufällig ist, sondern vielmehr ähnliche Preisverläufe auch ähnliche Reaktionen hervorrufen. Ausgehend von der Untersuchung der komplexen Korrelationen in Finanzmarktzeitreihen wird die Frage behandelt, welche Eigenschaften sich beim Wechsel von einem positiven Trend zu einem negativen Trend verändern. Eine empirische Quantifizierung mittels Reskalierung liefert das Resultat, dass unabhängig von der betrachteten Zeitskala neue Preisextrema mit einem Anstieg des Transaktionsvolumens und einer Reduktion der Zeitintervalle zwischen Transaktionen einhergehen. Diese Abhängigkeiten weisen Charakteristika auf, die man auch in anderen komplexen Systemen in der Natur und speziell in physikalischen Systemen vorfindet. Über 9 Größenordnungen in der Zeit sind diese Eigenschaften auch unabhängig vom analysierten Markt - Trends, die nur für Sekunden bestehen, zeigen die gleiche Charakteristik wie Trends auf Zeitskalen von Monaten. Dies eröffnet die Möglichkeit, mehr über Finanzmarktblasen und deren Zusammenbrüche zu lernen, da Trends auf kleinen Zeitskalen viel häufiger auftreten. Zusätzlich wird eine Monte Carlo-basierte Simulation des Finanzmarktes analysiert und erweitert, um die empirischen Eigenschaften zu reproduzieren und Einblicke in deren Ursachen zu erhalten, die zum einen in der Finanzmarktmikrostruktur und andererseits in der Risikoaversion der Handelsteilnehmer zu suchen sind. Für die rechenzeitintensiven Verfahren kann mittels Parallelisierung auf einer Graphikkartenarchitektur eine deutliche Rechenzeitreduktion erreicht werden. Um das weite Spektrum an Einsatzbereichen von Graphikkarten zu aufzuzeigen, wird auch ein Standardmodell der statistischen Physik - das Ising-Modell - auf die Graphikkarte mit signifikanten Laufzeitvorteilen portiert. Teilresultate der Arbeit sind publiziert in [PGPS07, PPS08, Pre11, PVPS09b, PVPS09a, PS09, PS10a, SBF+10, BVP10, Pre10, PS10b, PSS10, SBF+11, PB10].