Thesis--Universität Dortmund, 2006. / Includes bibliographical references.

published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

published_or_final_version / Applied Geosciences / Master / Master of Science

Tian Shan is one of the most important orogenic belts in central Asia. It has been reactivated as a result of the Cenozoic India-Eurasia collision. Dating of the late Cenozoic tectonic deformation of Tian Shan and its piedmonts is important for understanding the mountain building as well as evaluating seismic hazards in the region. This study is focused on the applications of optical dating to the late Quaternary uplift and thrust activity along Manas River, in the northern piedmont of the Tian Shan, China. The sediments on river terraces were dated with optical dating. The elevations were measured with the kinematic global position system (GPS). The results suggest that two phases can be identified according to the significantly different river incision rates. One phase was from ~20 ka to ~4.8 ka, with a much slower incision rate of ~ 2.2 ± 0.6 mm/yr. The other phase was from ~4.8 ka to present, with a faster incision rate of ~ 13.5 ± 0.6 mm/yr. The accelerated incision rate of Manas River was mainly attributed to the tectonic forces, suggesting that the tectonic uplift was significantly intensified since ~4.8 ka in the northern piedmont of Tian Shan. The study region has suffered from multiple thrust activities during the late Quaternary, which led to the intensive deformations of the river terraces. By studying the deformed terraces, I evaluated the timing of the past thrust activities as well as the vertical slip rate of the thrust faults. The results demonstrated that the thrust activity intensified during the late Holocene, as manifested by the more frequent thrust activities and higher vertical slip rates. Both quartz and potassium feldspar can be as dosimeters for optical dating of sediments. However, quartz OSL is sometimes seriously impeded with problems such as very dim signals and insufficient bleaching problems. K-feldspar has attractive advantages over quartz, despite of problem of anomalous fading. K-feldspar was explored in this study, by investigating the relationship between the infrared stimulated luminescence (IRSL) and blue light stimulated luminescence (BLSL) signals. For IRSL and BLSL at 60 °C, it was suggested that most of the IRSL could be bleached by blue light (BL), while the BLSL could only be partially bleached by infrared (IR) stimulation. Besides, the fast and medium components of BLSL were mainly associated with the IRSL. If IR stimulation temperature was raised from 60 to 200 °C, at least two portions of the IRSL signals at 200 °C were observed. One portion could be bleached by BL at 60 °C and the other portion was hardly bleached by BL at 60 °C. Dating of K-feldspar from the various signals provided cross-checking for the reliability of quartz OSL for dating sedimentary samples. / published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

New applications of the optically stimulated luminescence (OSL) dating were carried out with the aim of understanding late Quaternary activities for the Tibetan Plateau. This included studying the slip rate of the Altyn Tagh Fault, northeast Tibetan Plateau, and revealing the environmental changes derived from large inland lake’s evolution, central south Tibet. Two deflected streams across the Altyn Tagh Fault close to Aksay (39°24.572’N, 94°16.012’E) were investigated. Geomorphological analysis suggests that loess covering deflected stream banks has recorded past faulting events. A conceptual model is proposed illustrating the relationship. OSL dating of sixteen loess samples at both streams support the model, suggesting the loess is deposited episodically after fault strikes and subsequent channel wall refreshment. The age and offset indicate a slip rate of 11 ±2 mm/yr for this part of the Altyn Tagh Fault. Another river section near Aksay was also investigated for the slip rate information. Two risers between three terraces are clearly offset; OSL dating of loess covering terrace surfaces yielded terrace ages. Using the upper-terrace age to represent riser displacement duration, the rate is estimated to be 12 ±1 mm/yr. The result suggests that using upper terrace is more suitable in this region. Notably, though, the slow rate is at odds with proposals that assume high-speed extrusion (~23 mm/year) of the Tibetan Plateau being accommodated by the Altyn Tagh Fault. Palaeo-shorelines around the third largest lake in Tibet, Zhari Namco, were for the first time systematically investigated using OSL dating. Twenty-two sediment samples from eleven shorelines indicate that the water level has dropped ~128 m and the lake has undergone stepwise shrinkage since 8.2 ka. Digital elevation model calculation indicates the lake has shrunk from 4605 km2 in size at 8.2 ka to 996 km2 at present, which is equivalent to ~300 km3 of water. This implies a significant reduction in precipitation over the past 8.2 ka, a result of weakening Indian Monsoon or a shift of monsoon circulation path. The result is consistent with other lake-core, ice-core climate proxies and solar insolation changes, implying the dominance of a weakening Indian Monsoon over central Tibet in the Holocene. Using the elevation of the highest shoreline of the four largest lakes in Tibet, the early Holocene Pan-lake hypothesis is proposed for the central Tibet. In addition to these applications of OSL dating, technical studies on sensitivity changes and residual doses have been carried out for potassium rich feldspar (K-feldspar). Recent development of infrared stimulated luminescence (IRSL) signals from K-feldspar has shown great potential for extending the datable range for OSL dating. Sensitivity changes and residual doses of post-IR IRSL and multi-elevated -temperature post-IR IRSL protocols for K-feldspar were studied. A sensitivity decrease is observed after adopting a high temperature IRSL. IRSL signals stimulated at high temperature are found to contain large residual doses. The residual dose rises with stimulation time, suggesting that the initial part of IRSL signals contains more easy-to-bleach signals comparing with the later part. / published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

Diagnosis of acute pancreatitis (AP) is erroneous in up to one third of patients when based on clinical criteria and elevated serum amylase values. Furthermore, according to autopsy reports fatal pancreatitis remains clinically undiagnosed in 22 to 86 % of hospitalised patients. Consequently, search for better methods for the diagnosis of AP seems not only justified but urgent. The pancreas secretes an nonspecific lipase, the carboxylic ester hydrolase (CEH) with molecular properties different from other pancreatic secretory enzymes. These differences may imply that sites and rates of clearances from blood of pancreatic enzymes differ. Except for the pancreas this enzyme is secreted from the lactating mammary gland with milk. A sensitive and reproducible sandwich-ELISA for quantitative determination of CEH was developed. When establishing referent values it was noted that in individuals aged 20 to 65 years serum concentrations of CEH did not depend on age, gender, the time of the day or duration from food intake to blood sampling, or use of nicotine. The mammary gland did not contribute significantly to basal serum levels of CEH; enzyme levels in lactating women or women with mammary tumours were identical to those of the reference population. Seventy percent of patients with the diagnosis AP, based on elevated serum amylase levels and abdominal pain, had elevated CEH values. Among the patients with elevated amylase alone a probable cause of pancreatitis was lacking in the majority of patients. Contrastingly, a likely cause of AP could be identified in all patients presenting with abdominal pain and elevated CEH levels alone. These findings suggested that an elevated CEH level indicated AP more reliably than an elevated amylase level. In patients with AP diagnosed by contrast enhanced computed tomography (CECT) alone, or combined with histopathological diagnosis, serum CEH levels were elevated on admission in all but one patient, and in all within the next 24 h. Furthermore, in patients with severe pancreatitis CEH levels remained at a raised level from the second to at least the 10:th day following admission, whereas a significant decrease was noted in patients with mild pancreatitis. In contrast, serum amylase values were higher in patients with mild pancreatitis during the observation period than in those with severe pancreatitis. CEH levels were higher in patients with three or more Ranson signs than in those with less than three signs from the first day after admission. CEH levels were within referent range in 164 patients without known pancreatic disease admitted due to abdominal emergency conditions, or due to planned surgery for chronic extrapancreatic gastrointestinal diseases, and 16 patients having CECT without pathological findings in the pancreas. This suggests that AP can be excluded with very high degree of probability in presence of non-elevated CEH levels. A sandwich ELISA for determination of Guinea pig CEH and a model for graded pancreatitis in the same species were developed. CEH levels showed proportional to severity of inflammation, thus confirming previous clinical observations. CEH levels in bile were proportional to inflammation, while it was absent in urine. Amylase levels in urine were identical regardless of severity of inflammation, but low in bile. These results suggested differences in sites and rates of clearance between the two enzymes. Seemingly elevated CEH levels allowed identification of clinically significant pancreatitis following ERCP, which amylase levels did not. The presented studies have shown that quantitative determination in serum of CEH by the described method is a more reliable test for the diagnosis of AP than determination of amylase activity. The differences between CEH and amylase are, at least partly, due to differences in molecular properties determining rates and routes of clearances of the two enzymes from serum. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1994, härtill 5 uppsatser.</p> / digitalisering@umu.se

DNA is packaged into the nucleus of a mammalian cell as a nucleoprotein complex called chromatin. Changes in chromatin structure occur during processes that are critical to an understanding of mammalian cell biology such as cell division. Existing fixed-cell techniques have provided insight into chromatin organization in the mammalian nucleus. In addition, fluorescence microscopy techniques have allowed us to study changes in chromatin structure in living cells. However, most of these fluorescence techniques cannot be used for tissue imaging or long-term imaging due to photobleaching. In this thesis, we demonstrate that a label-free technique called Stimulated Raman Scattering (SRS) microscopy can be used to solve these problems and study chromatin structure in living mammalian cells both in culture and in tissue. SRS is a vibrational microscopy technique that takes advantage of intrinsic contrast arising from specific chemical bonds in a molecule. Nucleic acids have specifc phosphate and CH vibrations that can be used to determine their cellular distributions. Imaging at specific phosphate peaks using fingerprint SRS microscopy allows the detection of polytene chromosomes in Drosophila salivary gland cells and condensed chromatin in metaphase mammalian cells. In addition, we develop a technique called multicolor SRS microscopy, in which we image at several wavelengths across the CH vibrational band, and then use linear combination to simultaneously determine the nucleic acid, lipid and protein distributions in living mammalian cells. This technique achieves greater contrast than imaging at the phosphate vibrational peak due to the stronger SRS signal in the high wavenumber CH band and so allows us to determine chromatin structure in interphase mammalian cells. This technique also allows long-term imaging of living mammalian cells and the imaging of tissue such as mouse skin. The technique is used to monitor mammalian cell division in culture and paves the way for similar studies in living tissue. This technique will provide insight into cell division, differentiation and apoptosis during development and in disease models such as cancer.

The understanding of the biological processes at the cellular and subcellular level requires the ability to directly visualize them. Fluorescence microscopy played a key role in biomedical imaging because of its high sensitivity and specificity. However, traditional fluorescence microscopy has a limited resolution due to optical diffraction. In recent years, various approaches have been developed to overcome the diffraction limit. Among these techniques, nonlinear structured illumination microscopy (SIM) has been demonstrated a fast and full field superresolution imaging tool, such as Saturated-SIM and Photoswitching-SIM. In this dissertation, I report a new approach that applies nonlinear structured illumination by combining a uniform excitation field and a patterned stimulated emission depletion (STED) field. The nature of STED effect allows fast switching response, negligible stochastic noise during switching, low shot noise and theoretical unlimited resolution, which predicts STED-SIM to be a better nonlinear SIM. After the algorithm development and the feasibility study by simulation, the STED-SIM microscope was tested on fluorescent beads samples and achieved full field imaging over 1 x 10 micron square at the speed of 2s/frame with 4-fold improved resolution. Our STED-SIM technique has been applied on biological samples and superresolution images with tubulin of U2OS cells and granules of neuron cells have been obtained. In this dissertation, an effort to apply a field enhancement mechanism, surface plasmon resonance (SPR), to nonlinear STED-SIM has been made and around 8 time enhancement on STED quenching effect was achieved. Based on this enhancement on STED, 1D SPR enhanced STED-SIM was built and 50 nm resolution of fluorescence beads sample was achieved. Algorithm improvement is required to achieve full field superresolution imaging with SPR enhanced STED-SIM. The application of nonlinear structured illumination in two photon light-sheet microscopy is also studied in this dissertation. Fluorescent cellular imaging of deep internal organs is highly challenging because of the tissue scattering. By combining two photon Bessel beam light-sheet microscopy and nonlinear SIM, 3D live sample imaging at cellular resolution in depth beyond 200 microns has been achieved on live zebrafish. Two-color imaging of pronephric glomeruli and vasculature of zebrafish kidney, whose cellular structures located at the center of the fish body are revealed in high clarity.

High-speed optical networks will require all-optical signalprocessing to avoid bottleneck due to optical-to-electrical (O/E)and electrical-to-optical (E/O) conversion. Enabling of opticalprocessing tasks such as optical buffering and data synchronizationwill require large tunable delay. Recently, slow-light physics gotwide attention to generate tunable delay. However, for a slow-lightsystem large delay comes at the expense of increased distortion.This dissertation presents a study of the slow-light systems andquantifies the limitations imposed on delay due to distortion andsystem resource constraints. Optimal designs for two- and three-lineBrillouin slow-light systems showed fractional pulse delay of up to1.7 compared to a single-line gain system. Optimal designs forbroadband Brillouin gain system showed upto 100\% delay improvementcompared to the Gaussian pump. Wavelength conversion and dispersionbased tunable delay systems showed bit delay of 15 bits. An opticalbuffer based on photorefractive medium for real-time data storagewas demonstrated by storing and retrieving a 7-bit data sequence.

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