Cross Recurrence Plot Based Synchronization of Time Series

The method of recurrence plots is extended to the cross recurrence plots (CRP), which among others enables the study of synchronization or time differences in two time series. This is emphasized in a distorted main diagonal in the cross recurrence plot, the line of synchronization (LOS). A non-parametrical fit of this LOS can be used to rescale the time axis of the two data series (whereby one of it is e.g. compressed or stretched) so that they are synchronized. An application of this method to geophysical sediment core data illustrates its suitability for real data. The rock magnetic data of two different sediment cores from the Makarov Basin can be adjusted to each other by using this method, so that they are comparable.Comment: Nonlinear Processes in Geophysics, 9, 2002, in pres

Mechanisms of Emulsion Destabilization: An Investigation of Surfactant, Stabilizer, and Detergent Based Formulations Using Diffusing Wave Spectroscopy

Conventional approaches for studying emulsions, such as microscopy and macroscopic phase tracking, present challenges when it comes to establishing detailed mechanistic descriptions of the impact of emulsifier and stabilizer additives. Additionally, while a combination of sizing methods and macroscopic phase tracking can provide insights into droplet size changes and concentration, the use of multiple measurements can be cumbersome and error-prone. It is the focus of this work, to present a new method for studying water in oil (W/O) emulsions that involves using diffusing wave spectroscopy (DWS) to examine the impact of three different surface stabilizing additives at varying concentrations. By monitoring changes in the transport mean free path length ($l^*$) it is demonstrated that a single DWS measurement provides similar insights to traditional methods. In addition to revealing physical dynamics inaccessible through conventional techniques. Nine specific additives were analyzed and detailed characterization and classification with relation to mechanisms of destabilization are detailed, and provide useful in improving formulations. The wealth of information provided by DWS measurements suggests that it could be useful in developing formulations tailored to specific use cases, rather than just in fundamental research

Palaeolimnology of Lake Sapanca and identification of historic earthquake signals, Northern Anatolian Fault Zone (Turkey)

Lake Sapanca is located on a strand of the Northern Anatolian Fault Zone (NAFZ, Turkey), where a series of strong earthquakes (Ms >6.0) have occurred over the past hundred years. Identifying prehistoric earthquakes in and around Lake Sapanca is key to a better understanding of plate movements along the NAFZ. This study contributes to the development of palaeolimnological tools to identify past earthquakes in Lake Sapanca. To this end several promising proxies were investigated, specifically lithology, magnetic susceptibility, grain size (thin-section and laser analysis), geochemistry, pollen concentration, diatom assemblages, 137Cs and 210Pb. Sedimentological indicators provided evidence for reworked, turbidite-like or homogeneous facies (event layers) in several short cores (<45 cm). Other indicators of sediment input and the historical chronicles available for the area suggest that three of these event layers likely originated from the AD 1957, 1967 and 1999 earthquakes. Recent changes in sediment deposition and nutrient levels have also been identified, but are probably not related to earthquakes. This study demonstrates that a combination of indicators can be used to recognize earthquake-related event layers in cores that encompass a longer period of time

Authigenic magnetite formation from goethite and hematite and chemical remanent magnetization acquisition

Post-print (lokagerð höfundar)The iron oxyhydroxide goethite is unstable at elevated temperatures and can transform to magnetite under reducing conditions. In this study, various heating experiments were conducted to simulate Fe-mineral transformations during pyrogenic or burial diagenesis alteration in the presence of organic matter. Thermomagnetic measurements, capsule heating experiments and thermo-chemical remanence acquisition measurements were performed to determine the effect of organic carbon additions on samples containing synthetic microcrystalline goethite, microcrystalline hematite or nanocrystalline goethite. Changes in magnetic properties with heating were monitored to characterize the magnetic behavior of secondary magnetite and hematite formed during the experiments. Authigenic magnetite formed in all samples containing organic C, while goethite heated without organic C altered to poorly crystalline pseudomorphic hematite. The concentration of organic matter was found to have little influence on the rate or extent of reaction or on the characteristics of the secondary phases. Authigenic magnetite formed from microcrystalline goethite and hematite dominantly behaves as interacting single-domain particles, while nanophase goethite alters to a mixture of small single-domain and superparamagnetic magnetite. Authigenic magnetite and hematite both acquire a stable thermo-chemical remanence on heating to temperatures between 350 and 600°C, although the remanence intensity acquired below 500°C is much weaker than that at higher temperatures. Reductive transformation of fine-grained goethite or hematite is therefore a potential pathway for the production of authigenic magnetite and the generation of stable chemical remanence that may be responsible for remagnetization in organic matter-bearing sedimentary rocks.Alexander von Humboldt FoundationPeer Reviewe

Domain-wall dynamics in 4C pyrrhotite at low temperature

Monoclinic 4C pyrrhotite (Fe7S8) is ferrimagnetic due to an ordered defect structure with alternating vacancy and vacancy-free sublattices. Its low-temperature magnetic transition near 35 K is characterized by the distinct increase in coercivity and remanent magnetization. The increase of these parameters has been attributed to changes in the domain wall structure. We present static and dynamic magnetization data of a powder sample to study the domain-wall dynamics across the low-temperature transition. The amplitude-dependent ac susceptibility and the ferromagnetic resonance spectroscopy indicate that the hardening of the domain-wall pinning at the transition occurs simultaneously with the decrease in initial saturation remanent magnetization. These two effects are explained by the enhanced inhomogeneity of the bulk material caused by the persistency of the ordered vacancies and by newly formed defects due to localized distortion of Fe(II) sites in the vacancy-free sublattice. The generated localized defects are the link between the domain wall dynamics and the low-temperature transition in 4C pyrrhotit

Bias-free photoelectrochemical water splitting with photosystem II on a dye-sensitized photoanode wired to hydrogenase

Natural photosynthesis stores sunlight in chemical energy carriers, but it has not evolved for the efficient synthesis of fuels, such as H2. Semi-artificial photosynthesis combines the strengths of natural photosynthesis with synthetic chemistry and materials science to develop model systems that overcome Nature’s limitations, such as low-yielding metabolic pathways and non-complementary light absorption by Photosystem (PS) I and II. Here, we report a bias-free semi-artificial tandem platform that wires PSII to hydrogenase for overall water splitting. This photoelectrochemical cell integrated the red and blue light-absorber PSII with a green light-absorbing diketopyrrolopyrrole dye-sensitised TiO2 photoanode enabling complementary panchromatic solar light absorption. Effective electronic communication at the enzyme-material interface was engineered using an Os complex-modified redox polymer on a hierarchically-structured TiO2. This system provides a design protocol for bias-free semi-artificial Z-schemes in vitro and provides an extended toolbox of biotic and abiotic components to re-engineer photosynthetic pathways.ERC Consolidator Grant, EPSRC (nanoDTC, DTA studentship), Christian Doppler Research Association, OMV Group, Royal Society Newton International Fellowship, Cluster of Excellence RESOLV (DFG) and European Unions' Horizon 202

Evidence for geomagnetic excursions recorded in Brunhes and Matuyama Chron lavas from the trans‐Mexican volcanic belt

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99072/1/arar_methodology.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/99072/2/jgrb50214.pd

Mass movement deposits in the 3.6 Ma sediment record of Lake El'gygytgyn, Far East Russian Arctic

This paper focuses on the characterization and genesis of mass movement deposits (MMDs) in the Quater- nary and Pliocene sediments of Lake El’gygytgyn, Far East Russian Arctic. Three partly overlapping holes were drilled into the 320 m long sediment record at International Conti- nental Scientific Drilling Program (ICDP) Site 5011-1 in the lake basin, recovering the Quaternary almost completely, and the Pliocene down to 3.6 Ma with 52 % recovery. Mass move- ment deposits were investigated in all three cores, based on macroscopical core descriptions, radiographic images, high- resolution magnetic susceptibility and gamma-ray density. Five different types of MMDs were identified: turbidites, grain-flow deposits, debrites, slumps and slides. These are formed by transitional mass movement processes, and thus can be co-generic. An initial slope failure is thought to trans- form into a debris flow that deforms frontal sediments, partly disintegrates and dilutes into a turbidity flow. Turbidites are by far the most frequent MMD type in the lake center. They occur throughout the record in all pelagic sedimentary fa- cies, but they are thinner in facies formed during cold cli- mate conditions. All other MMDs, by contrast, incise exclu- sively the pelagic facies deposited during warm climates. In the 123 m thick Quaternary composite sediment record 230 mass movement events are identified, comprising 33% of the sediment length. Turbidites contribute 93 % of the num- ber of Quaternary MMDs, but only 35 % of their thickness. In the Pliocene sediments between 123 and 320 m, 181 ad- ditional mass movement deposits are identified, which con- stitute ⇠ 33 % of the recovered sediments. The mean recur- rence interval for MMDs is 11 and 5 ka in the Quaternary and Pliocene, respectively