Quantifying ice-shelf basal melt and ice-stream dynamics using high-resolution DEM and GPS time series

Thesis (Ph.D.)--University of Washington, 2016-06

High resolution provenancing of long travelled dust deposited on the Southern Alps, New Zealand

On 7 February 2000 an atypical orange discolouration of snowfields in the central Southern Alps, New Zealand occurred following the passage of a cold front. Analysis of snow samples identified fine orangey-brown dust mixed with much coarser grey dust. Air parcel forward trajectories from dust sources in southern and central Australia, where dust storms were reported on 4 February 2000, were computed to identify the deposits source. Geochemical analyses of the dust deposit using 26 trace elements, unaffected by regional air pollution and gravitational sorting, indicate that 20% of the dust was sourced from western New South Wales, with 45% from the eastern Eyre Peninsula of South Australia and the remaining 35% was local New Zealand dust. This provenancing approach provides a spatial resolution of long travelled dust sourcing not previously achieved. (c) 2005 Elsevier B.V. All rights reserved.

A high-resolution sedimentology and age determination of core PS2185 from the central Arctic Ocean

A high-resolution multiparameter stratigraphy allows the identification of late Quaternary glacial and interglacial cycles in a central Arctic Ocean sediment core. Distinct sandy layers in the upper part of the otherwise fine-grained sediment core from the Lomonosov Ridge (lat 87.5°N) correlate to four major glacials since ca. 0.7 Ma. The composition of these ice-rafted terrigenous sediments points to a glaciated northern Siberia as the main source. In contrast, lithic carbonates derived from North America are also present in older sediments and indicate a northern North American glaciation since at least 2.8 Ma. We conclude that large-scale northern Siberian glaciation began much later than other Northern Hemisphere ice sheets.

High resolution study of narrow tailed radio galaxies in clusters

Clusters of galaxies are the most massive and large gravitationally bounded systems in the whole Universe. Their study is of fundamental importance to constrain cosmological parameters and to obtain informations regarding various kind of emission in different wavebands. In particular, in the radio domain, beside the diffuse emission, the study is focused on the radio galaxies emission. Radio galaxies in clusters can have peculiar morphology, since they interact with the intracluster medium (ICM) in which they are embedded. Particularly, in this thesis we focused our attention on the so-called Narrow-Angle Tailed radio galaxies (NAT), which present radio jets that are bent at extreme angle, up to 90 degrees, from their original orientation. Some NAT show a narrow extended structure and the two radio tails are not resolved even with high resolution radio observations. An example is provided by the source IC310, in the Perseus Cluster, whose structure has been recently interpreted as due to Doppler boosting effects of a relativistic jet oriented at a small angle with respect to the line of sight. If the structure is due to relativistic effects, this implies that the jets are relativistic at about 400 kpc from the core, but this is in contrast with unified models, which predict that for low-power radio source (NAT are classified as FRI radio galaxies) the jets decelerate to sub-relativistic speed within a few kpc from the core. To investigate this scientific topic, in this thesis we have analyzed the innermost structure of a sample of eleven radio galaxies showing a very narrow NAT structure. We can conclude that the structure of these radio galaxies is different from that of IC310. These radio galaxies are indeed strongly influenced by environmental effects and are similar to classical NAT sources.

High-Resolution In Situ Oxygen-Argon Studies of Surface Biological and Physical Processes in the Polar Oceans

The Arctic Ocean and Western Antarctic Peninsula (WAP) are the fastest warming regions on the planet and are undergoing rapid climate and ecosystem changes. Until we can fully resolve the coupling between biological and physical processes we cannot predict how warming will influence carbon cycling and ecosystem function and structure in these sensitive and climactically important regions. My dissertation centers on the use of high-resolution measurements of surface dissolved gases, primarily O2 and Ar, as tracers or physical and biological functioning that we measure underway using an optode and Equilibrator Inlet Mass Spectrometry (EIMS). Total O2 measurements are common throughout the historical and autonomous record but are influenced by biological (net metabolic balance) and physical (temperature, salinity, pressure changes, ice melt/freeze, mixing, bubbles and diffusive gas exchange) processes. We use Ar, an inert gas with similar solubility properties to O2, to devolve distinct records of biological (O2/Ar) and physical (Ar) oxygen. These high-resolution measurements that expose intersystem coupling and submesoscale variability were central to studies in the Arctic Ocean, WAP and open Southern Ocean that make up this dissertation.

Key findings of this work include the documentation of under ice and ice-edge blooms and basin scale net sea ice freeze/melt processes in the Arctic Ocean. In the WAP O2 and pCO2 are both biologically driven and net community production (NCP) variability is controlled by Fe and light availability tied to glacial and sea ice meltwater input. Further, we present a feasibility study that shows the ability to use modeled Ar to derive NCP from total O2 records. This approach has the potential to unlock critical carbon flux estimates from historical and autonomous O2 measurements in the global oceans.

The morphology of ordered block copolymer patterns as probed by high resolution imaging

The microphase separation of block copolymer (BCP) thin films can afford a simple and cost-effective means to studying nanopattern surfaces, and especially the fabrication of nanocircuitry. However, because of complex interface effects and other complications, their 3D morphology, which is often critical for application, can be more complex than first thought. Here, we describe how emerging microscopic methods may be used to study complex BCP patterns and reveal their rich detail. These methods include helium ion microscopy (HIM) and high resolution x-section transmission electron microscopy (XTEM), and complement conventional secondary electron and atomic force microscopies (SEM and TEM). These techniques reveal that these structures are quite different to what might be expected. We illustrate the advances in the understanding of BCP thin film morphology in several systems, which result from this characterization. The systems described include symmetric, lamellar forming polystyrene-b-polymethylmethacrylate (PS-b-PMMA), cylinder forming polystyrene-b-polydimethylsiloxane (PS-b-PDMS), as well as lamellar and cylinder forming patterns of polystyrene-b-polyethylene oxide (PS-b-PEO) and polystyrene-b-poly-4-vinylpyridine (PS-b-P4VP). Each of these systems exhibits more complex arrangements than might be first thought. Finding and developing techniques whereby complex morphologies, particularly at very small dimensions, can be determined is critical to the practical use of these materials in many applications. The importance of quantifying these complex morphologies has implications for their use in integrated circuit manufacture, where they are being explored as alternative pattern forming methods to conventional UV lithography.

A high-flux BEC source for mobile atom interferometers

Quantum sensors based on coherent matter-waves are precise measurement devices whose ultimate accuracy is achieved with Bose-Einstein condensates (BECs) in extended free fall. This is ideally realized in microgravity environments such as drop towers, ballistic rockets and space platforms. However, the transition from lab-based BEC machines to robust and mobile sources with comparable performance is a challenging endeavor. Here we report on the realization of a miniaturized setup, generating a flux of 4x10(5) quantum degenerate Rb-87 atoms every 1.6 s. Ensembles of 1 x 10(5) atoms can be produced at a 1 Hz rate. This is achieved by loading a cold atomic beam directly into a multi-layer atom chip that is designed for efficient transfer from laser-cooled to magnetically trapped clouds. The attained flux of degenerate atoms is on par with current lab-based BEC experiments while offering significantly higher repetition rates. Additionally, the flux is approaching those of current interferometers employing Raman-type velocity selection of laser-cooled atoms. The compact and robust design allows for mobile operation in a variety of demanding environments and paves the way for transportable high-precision quantum sensors.

Climate variability of the last 1000 years in the NW Pacific: high resolution, multi-biomarker records from Lake Toyoni

The East Asian Monsoon (EAM) is an active component of the global climate system and has a profound social and economic impact in East Asia and its surrounding countries. Its impact on regional hydrological processes may influence society through industrial water supplies, food productivity and energy use. In order to predict future rates of climate change, reliable and accurate reconstructions of regional temperature and rainfall are required from all over the world to test climate models and better predict future climate variability. Hokkaido is a region which has limited palaeo-climate data and is sensitive to climate change. Instrumental data show that the climate in Hokkaido is influenced by the East Asian Monsoon (EAM), however, instrumental data is limited to the past ~150 years. Therefore down-core climate reconstructions, prior to instrumental records, are required to provide a better understanding of the long-term behaviour of the climate drivers (e.g. the EAM, Westerlies, and teleconnections) in this region. The present study develops multi-proxy reconstructions to determine past climatic and hydrologic variability in Japan over the past 1000 years and aid in understanding the effects of the EAM and the Westerlies independently and interactively. A 250-cm long sediment core from Lake Toyoni, Hokkaido was retrieved to investigate terrestrial and aquatic input, lake temperature and hydrological changes over the past 1000-years within Lake Toyoni and its catchment using X-Ray Fluorescence (XRF) data, alkenone palaeothermometry, the molecular and hydrogen isotopic composition of higher plant waxes (δD(HPW)). Here, we conducted the first survey for alkenone biomarkers in eight lakes in the Hokkaido, Japan. We detected the occurrence of alkenones within the sediments of Lake Toyoni. We present the first lacustrine alkenone record from Japan, including genetic analysis of the alkenone producer. C37 alkenone concentrations in surface sediments are 18µg C37 g−1 of dry sediment and the dominant alkenone is C37:4. 18S rDNA analysis revealed the presence of a single alkenone producer in Lake Toyoni and thus a single calibration is used for reconstructing lake temperature based on alkenone unsaturation patterns. Temperature reconstructions over the past 1000 years suggest that lake water temperatures varies between 8 and 19°C which is in line with water temperature changes observed in the modern Lake Toyoni. The alkenone-based temperature reconstruction provides evidence for the variability of the EAM over the past 1000 years. The δD(HPW) suggest that the large fluctuations (∼40‰) represent changes in temperature and source precipitation in this region, which is ultimately controlled by the EAM system and therefore a proxy for the EAM system. In order to complement the biomarker reconstructions, the XRF data strengthen the lake temperature and hydrological reconstructions by providing information on past productivity, which is controlled by the East Asian Summer monsoon (EASM) and wind input into Lake Toyoni, which is controlled by the East Asian Winter Monsoon (EAWM) and the Westerlies. By combining the data generated from XRF, alkenone palaeothermometry and the δD(HPW) reconstructions, we provide valuable information on the EAM and the Westerlies, including; the timing of intensification and weakening, the teleconnections influencing them and the relationship between them. During the Medieval Warm Period (MWP), we find that the EASM dominated and the EAWM was suppressed, whereas, during the Little Ice Age (LIA), the influence of the EAWM dominated with time periods of increased EASM and Westerlies intensification. The El Niño Southern Oscillation (ENSO) significantly influenced the EAM; a strong EASM occurred during El Niño conditions and a strong EAWM occurred during La Niña. The North Atlantic Oscillation, on the other hand, was a key driver of the Westerlies intensification; strengthening of the Westerlies during a positive NAO phase and weakening of the Westerlies during a negative NAO phase. A key finding from this study is that our data support an anti-phase relationship between the EASM and the EAWM (e.g. the intensification of the EASM and weakening of the EAWM and vice versa) and that the EAWM and the Westerlies vary independently from each other, rather than coincide as previously suggested in other studies.

High-resolution Transcript Profiling Of The Atypical Biotrophic Interaction Between Theobroma Cacao And The Fungal Pathogen Moniliophthora Perniciosa.

Witches' broom disease (WBD), caused by the hemibiotrophic fungus Moniliophthora perniciosa, is one of the most devastating diseases of Theobroma cacao, the chocolate tree. In contrast to other hemibiotrophic interactions, the WBD biotrophic stage lasts for months and is responsible for the most distinctive symptoms of the disease, which comprise drastic morphological changes in the infected shoots. Here, we used the dual RNA-seq approach to simultaneously assess the transcriptomes of cacao and M. perniciosa during their peculiar biotrophic interaction. Infection with M. perniciosa triggers massive metabolic reprogramming in the diseased tissues. Although apparently vigorous, the infected shoots are energetically expensive structures characterized by the induction of ineffective defense responses and by a clear carbon deprivation signature. Remarkably, the infection culminates in the establishment of a senescence process in the host, which signals the end of the WBD biotrophic stage. We analyzed the pathogen's transcriptome in unprecedented detail and thereby characterized the fungal nutritional and infection strategies during WBD and identified putative virulence effectors. Interestingly, M. perniciosa biotrophic mycelia develop as long-term parasites that orchestrate changes in plant metabolism to increase the availability of soluble nutrients before plant death. Collectively, our results provide unique insight into an intriguing tropical disease and advance our understanding of the development of (hemi)biotrophic plant-pathogen interactions.

High resolution study of 104Pd(d,t)103Pd

Information collected in the present high resolution study of 104Pd(d,t)103Pd is interpreted within the systematics of the A ~ 100 region. The paper complements data previously presented by the S.Paulo Group, which were taken with the Pelletron-Enge-Spectrograph facility. A one-to-one correspondence to gamma ray results for 103Pd, collected by the Nuclear Data Sheets (NDS), was achieved and at least four open questions were settled. More reliable spectroscopic strengths were extracted in the present study.

Chemical abundances of 11 bulge stars from high-resolution, near-IR spectra

Context. It is debated whether the Milky Way bulge has characteristics more similar to those of a classical bulge than those of a pseudobulge. Detailed abundance studies of bulge stars are important when investigating the origin, history, and classification of the bulge. These studies provide constraints on the star-formation history, initial mass function, and differences between stellar populations. Not many similar studies have been completed because of the large distance and high variable visual extinction along the line-of-sight towards the bulge. Therefore, near-IR investigations can provide superior results. Aims. To investigate the origin of the bulge and study its chemical abundances determined from near-IR spectra for bulge giants that have already been investigated with optical spectra. The optical spectra also provide the stellar parameters that are very important to the present study. In particular, the important CNO elements are determined more accurately in the near-IR. Oxygen and other alpha elements are important for investigating the star-formation history. The C and N abundances are important for determining the evolutionary stage of the giants and the origin of C in the bulge. Methods. High-resolution, near-infrared spectra in the H band were recorded using the CRIRES spectrometer mounted on the Very Large Telescope. The CNO abundances are determined from the numerous molecular lines in the wavelength range observed. Abundances of the alpha elements Si, S, and Ti are also determined from the near-IR spectra. Results. The abundance ratios [O/Fe], [Si/Fe], and [S/Fe] are enhanced to metallicities of at least [Fe/H] = -0.3, after which they decline. This suggests that the Milky Way bulge experienced a rapid and early burst of star formation similar to that of a classical bulge. However, a similarity between the bulge trend and the trend of the local thick disk seems to be present. This similarity suggests that the bulge could have had a pseudobulge origin. The C and N abundances suggest that our giants are first-ascent red-giants or clump stars, and that the measured oxygen abundances are those with which the stars were born. Our [C/Fe] trend does not show any increase with [Fe/H], which is expected if W-R stars contributed substantially to the C abundances. No ""cosmic scatter"" can be traced around our observed abundance trends: the measured scatter is expected, given the observational uncertainties.

Magnetoelastic and thermal effects in the BiMn(2)O(5) lattice: A high-resolution x-ray diffraction study

High-resolution synchrotron x-ray diffraction measurements were performed on single crystalline and powder samples of BiMn(2)O(5). A linear temperature dependence of the unit cell volume was found between T(N)=38 and 100 K, suggesting that a low-energy lattice excitation may be responsible for the lattice expansion in this temperature range. Between T(*)similar to 65 K and T(N), all lattice parameters showed incipient magnetoelastic effects, due to short-range spin correlations. An anisotropic strain along the a direction was also observed below T(*). Below T(N), a relatively large contraction of the a parameter following the square of the average sublattice magnetization of Mn was found, indicating that a second-order spin Hamiltonian accounts for the magnetic interactions along this direction. On the other hand, the more complex behaviors found for b and c suggest additional magnetic transitions below T(N) and perhaps higher-order terms in the spin Hamiltonian. Polycrystalline samples grown by distinct routes and with nearly homogeneous crystal structure above T(N) presented structural phase coexistence below T(N), indicating a close competition amongst distinct magnetostructural states in this compound.

High-resolution transmission electron microscopy and electron backscatter diffraction in nanoscaled ferritic and ferritic-martensitic oxide dispersion strengthened-steels

For specific blanket and divertor applications in future fusion power reactors a replacement of presently considered reduced activation ferritic martensitic (RAFM) steels as a structural material by suitable oxide dispersion strengthened ferritic martensitic steels would allow a substantial increase of the operating temperature from similar to 823 to about 923 K. Due to this reason the RAFM-alloy ODS-Eurofer has already been developed and produced with industrial partners. In the He-cooled modular divertor concept, where temperatures above 923 K will arise, an ODS-steel with a purely ferritic matrix is advantageous, because of missing phase transitions. Due to this reason, a special ferritic ODS-steel is being manufactured as well. In this work the microstructures of these two ODS-alloy types, analysed mainly by high resolution TEM are compared, with respect to different manufacturing processes. In addition first results of high resolution EBSD scans together with determined orientation maps of the RAFM steel ODS-Eurofer will also be presented. (C) 2008 Elsevier B.V. All rights reserved.

Simultaneous Analysis of Tramadol, O-Desmethyltramadol, and N-Desmethyltramadol Enantiomers in Rat Plasma by High-Performance Liquid Chromatography-Tandem Mass Spectrometry: Application to Pharmacokinetics

Tramadol (T) is available as a racemic mixture of (+)-trans-T and (-)-trans-T. The main metabolic pathways are O-demethylation and N-demethylation, producing trans-O-desmethyltramadol (M1) and trans-N-desmethyltramadol (M2) enantiomers, respectively. The analgesic effect of T is related to the opioid activity of (+)-trans-T and (+)-M1 and to the monoaminergic action of (+/-)-trans-T. This is the first study using tandem mass spectrometry as a detection system for the simultaneous analysis of trans-T, M1, and M2 enantiomers. The analytes were resolved on a Chiralpak (R) AD column using hexane: ethanol (95.5:4.5, v/v) plus 0.1% diethylamine as the mobile phase. The quantitation limits were 0.5 ng/ml for trans-T and M1 and 0.1 ng/ml for M2. The method developed and validated here was applied to a pharmacokinetic study in rats. Male Wistar rats (n = 6 at each time point) received a single oral dose of 20 mg/kg racemic trans-T. Blood samples were collected up to 12 h after drug administration. The kinetic disposition of trans-T and M2 was enantioselective (AUC((+)/(-)) ratio = 4.16 and 6.36, respectively). The direction and extent of enantioselectivity in the pharmacokinetics of trans-T and M2 in rats were comparable to data previously reported for healthy volunteers, suggesting that rats are a suitable model for enantioselective studies of trans-T pharmacokinetics. Chirality 23: 287-293, 2011. (C) 2010 Wiley-Liss, Inc.

High-resolution bulk density images, using calibrated X-ray radiography of impregnated soil slices

Bulk density of undisturbed soil samples can be measured using computed tomography (CT) techniques with a spatial resolution of about 1 mm. However, this technique may not be readily accessible. On the other hand, x-ray radiographs have only been considered as qualitative images to describe morphological features. A calibration procedure was set up to generate two-dimensional, high-resolution bulk density images from x-ray radiographs made with a conventional x-ray diffraction apparatus. Test bricks were made to assess the accuracy of the method. Slices of impregnated soil samples were made using hardsetting seedbeds that had been gamma scanned at 5-mm depth increments in a previous study. The calibration procedure involved three stages: (i) calibration of the image grey levels in terms of glass thickness using a staircase made from glass cover slips, (ii) measurement of ratio between the soil and resin mass attenuation coefficients and the glass mass attenuation coefficient, using compacted bricks of known thickness and bulk density, and (iii) image correction accounting for the heterogeneity of the irradiation field. The procedure was simple, rapid, and the equipment was easily accessible. The accuracy of the bulk density determination was good (mean relative error 0.015), The bulk density images showed a good spatial resolution, so that many structural details could be observed. The depth functions were consistent with both the global shrinkage and the gamma probe data previously obtained. The suggested method would be easily applied to the new fuzzy set approach of soil structure, which requires generation of bulk density images. Also, it would be an invaluable tool for studies requiring high-resolution bulk density measurement, such as studies on soil surface crusts.