We investigate upper crustal anisotropy of the Endeavour Segment of the Juan de Fuca Ridge using shear wave splitting measurements of ~3000 earthquakes recorded during three years using the Keck seafloor seismic network. We apply a new cluster analysis of shear-wave splitting measurements to our database. The methodology reduces the use of subjective criteria and improves the accuracy of measurements in the presence of noisy data. Fast polarization directions at a given seismic station are constant and stable during the deployment; however, fast-polarization directions between stations vary significantly. We presume that the lack of consistency of shear wave splitting among seismic stations reflects the spatial distribution of anisotropy in the vicinity of the ridge axis. We infer that the variation of fast polarization directions and delay times is caused by spatial variations in shallow hydrogeological structures and the stress field. Local faults and fissures are unlikely to be the primary cause of this anisotropy since most of the fast polarization directions are not consistent with the ridge parallel trend of faults. Stress perturbations induced by magmatic injection into the axial magma chamber or spatial variation in the rates of a hydrothermal heat transfer may contribute to the observed heterogeneity in seismic anisotropy.

This literature analysis examines terahertz (THz) imaging as a non-invasive tool for the imaging of friction ridge detail from the first painted layer (imprimatura) in multilayered painted works of art. The paintings of interest are those created utilizing techniques developed during the Renaissance and still in use today. The goal of analysis serves to answer two questions. First, can THz radiation penetrate paint layers covering the imprimatura to reveal friction ridge information? Secondly, can the this technology recover friction ridge detail such that the fine details are sufficiently resolved to provide images suitable for comparison and identification purposes. If a comparison standard exists, recovered friction ridge detail from this layer can be used to establish linkages to an artist or between works of art. Further, it can be added to other scientific methods currently employed to assist with the authentication efforts of unattributed paintings. Flanked by the microwave and far-infrared edges, THz straddles the electronic and optic perspectives of the electromagnetic spectrum. As a consequence, this range is imparted with unique and useful properties. Able to penetrate and image through many opaque materials, its non-ionizing radiation is an ideal non-destructive technique that provides visual information from a painting’s sub-strata. Imaging is possible where refractive index differences exist between different paint layers. Though it is impossible, at present, to determine when a fingerprint was deposited, one can infer approximately when a print was created if it is recovered from the imprimatura layer of a painting, and can be subsequently attributed to a known source. Fingerprints are unique, a person is only able to deposit prints while their physical body is intact and thus, in some cases, the multiple layer process some artists use in their work may be used to the examiner’s advantage. Impressions of friction ridge detail have been recorded on receiving surfaces from human hands throughout time (and have also been discovered in works of art). Yet, the potential to associate those recorded impressions to a specific individual was only realized just over one hundred years ago. Much like the use of friction ridge skin, the relatively recently discovered THz range is now better understood; its tremendous potential unlocked by growing research and technology designed to exploit its unique properties.

Book Summary: Breathtaking photographs and original essays illuminate this tribute to the natural wonders of the Blue Ridge Parkway. The 469 miles of the Parkway run through some of the most magnificent landscapes in the United States, connecting the Shenandoah National Park to the Great Smoky Mountains National Park and these photographs capture the unique beauty of the region. Accompanying the images are heartfelt writings of regional poets and essayists who celebrate their abiding love for the Blue Ridge Mountains.

The purpose of this study was to investigate if the addition of biologic materials and/or oral steroids would affect horizontal bone gain, or the bone density of the grafted bone in horizontal alveolar ridge augmentations. A retrospective chart review was completed to assess the clinical and radiographic outcomes of 53 ridge augmentation patients. An average bone gain of 3.6mm of width was found in our study based on radiographic analysis. There were no statistically significant differences found in the linear bone gain with the addition of biologic materials and steroids. A marginally statistically significant difference was found in the bone density when biologics were added (p-value=0.0653). No statistically significant difference found in the bone density with the addition of oral steroids. The use of tenting screws and resorbable occlusive membranes and a combination of allograft and xenograft bone materials provides significant clinical and radiographic dimensional changes in alveolar ridge width.

Only a few studies have looked at microbial biogeography in soils and whether microorganisms are endemic to an area is still debatable. Tramway Ridge, a geothermal area on Mount Erebus, Antarctica, provides a unique opportunity due to its isolation and extreme conditions to explore the possibilities of microbial endemism and to identify novel Bacteria and Archaea. This site was chosen for a culture-independent study with a preliminary culturing survey for bacterial communities along three temperature gradients (65 C - 2.5'C). In addition, a physico-chemical analysis was undertaken to identify which environmental factors were driving the different diversity along the transects. An automated rRNA intergenic spacer analysis (ARISA) was used to assess the diversity across the transects using Bacteria and Cyanobacteria-specific primers and results showed that temperature and pH were the main drivers for these communities. Due to its unique physico-chemical and ARISA profile, a hot temperature site (T-3A, 65'C) was chosen for further investigation by bacterial and archaeal 16S rDNA clone libraries. Unique rDNA types among the 78 bacterial and 83 archaeal clones were identified by restriction fragment length polymophisms and 18 bacterial and 5 archaeal operational taxonomic units (gt97% identity) were observed. All of the bacterial sequences were deeply branching and loosely affiliated with other recognised bacterial divisions, with 40% of the sequences not affiliated to any genus. The archaeal clones were found to be deep-branching and sequences clustered together within the Crenarcaheota. In addition, two strains of Bacilli were isolated. The novel microorganisms show that the Tramway Ridge communities are unique from organisms found in other environments and show that quotEverything is (not) everywherequot.

Easter Island and Sala y Gomez are part of the Sala y Gomez Ridge, a broad band of high topography and scattered seamounts extending ESE from the East Pacific Rise. It has been proposed that the Sala y Gomez Ridge results from the movement of the Nazca Plate over a fixed melting spot in the mantle. To test this hypothesis volcanic rocks from Easter Island and Sala y Gomez were analyzed for their K-Ar ages and major element abundances. Subaerial Easter Island was constructed in three distinct episodes, occurring at 2.5 m.y., 0.9 m.y., and 0.4 m.y. ago. The youngest rocks on the island are the Roiho olivine basalts, and are probably less than 50,000 years old. Eruptive activity on Sala y Gomez was essentially contemporaneous with the early volcanism on Easter Island. No migration of volcanism with time is apparent along the Sala y Gomez Ridge, thus a major criterion of the melting spot hypothesis is not fulfilled. Volcanic rocks from Easter Island constitute a tholeiitic differentiation series; they are chemically similar to those from other islands situated near mid-ocean rise crests. The wide compositional spectrum is most likely the result of fractional crystallization from a basaltic parent liquid, though the data is ambiguous for the highly silicic differentiates. The youngest basalts possess more alkaline affinities which are probably not related to fractional crystallization from the earlier basalts. The alkaline nature of these rocks may be the result of a downward migration of the fusion zone with time, as the island moved eastward over a progressively thickening lithosphere. Volcanic rocks from Sala y Gomez belong to an alkali olivine basalt series. The fundamental chemical differences between the Easter Island and Sala y Gomez suites suggest that the two islands were not derived from a common source, as predicted by the melting spot hypothesis. The evidence does not support a melting spot origin for Easter Island, Sala y Gomez, and the Sala y Gomez Ridge. An alternative model involving diapiric intrusion and decompression melting of asthenosphere material along a major fracture in the Nazca Plate provides a better explanation for the data. Synchronous volcanism along the eastern extension of the Easter Island transform fault has given rise to the islands and seamounts on the Sala y Gomez Ridge. / Graduation date: 1975

A 3D seismic volume was acquired summer 2000 over the southern end of Hydrate Ridge (FIR), an anomalously shallow ridge 100 km offshore Newport, Oregon. The survey followed a succession of scientific expeditions aimed at studying the gas hydrates present in the shallow subsurface that gave the name to the ridge. This thesis consists of a seismic sequence analysis of the high-resolution (125 Hz) 3D survey. Identification of seismic units and interpretation of depositional sequences observed on the seismic sections is presented. The sequence analysis is compared with the results from nine sites cored during ODP Leg 204 during summer 2002. The first objective is to document in detail the stratigraphy of the ridge so that we can compare it with the gas hydrate distribution. The second is to reconstruct the structural evolution through time of this complex anticline as inferred from the depositional history. The result is a time series of structural evolutionary cross-sections as well as a series of paleo-bathymetric maps revealing the development of and interplay between the structures now buried in the subsurface of southern HR. The structural evolutionary diagrams show the existence of three anticlines, interpreted as thrust-related folds. They formed at the deformation front and controlled the distribution and deformation of the sediments during the Pleistocene. The current southern HR started its uplift less than 0.5 Ma. A seismic relict in the form of a double BSR is a witness to the evolution of the gas hydrate system of HR. It confirms the recent uplift of the ridge and consequent shallowing of the base of the gas hydrate stability zone (GHSZ). Further detailed studies of the stratigraphy reveal stratigraphic controls on the fluid flow, which in turn control the distribution of gas hydrates. Analysis of the amplitude map of the bottom-simulating reflector (BSR), which is a proxy for the free gas distribution, shows a relationship between anticlinal features within the older strata (older than 1.6 Ma) and strong amplitude anomalies of the BSR, which confirm previous observations suggesting a very low permeability for the young slope-basin sediments and an accumulation of gas within the older sediments underneath. / Graduation date: 2004

The Tugaloo terrane in the eastern Blue Ridge, located in the high-grade southern Appalachian crystalline core,contains small internal basement massifs, the Neoproterozoic Tallulah Falls Formation, and Paleozoic granitoid plutons. Detailed geologic mapping in the Lake Toxaway and eastern Big Ridge quadrangles was done to better understand the regional tectonic history. Whole-rock geochemistry was used to determine similarities between the augen phase of the 1.15 Ga Toxaway Gneiss and the 1.15 Ga Wiley Gneiss of northeastern Georgia. The study found that all eastern Blue Ridge orthogneisses are similar and probably share a source. The previously identified Whiteside, Looking Glass, and Pink Beds plutons, and the newly identified Horseshoe Rock and Round Mountain plutons were also characterized. All plutons are low-K, catazonal granodiorites and trondhjemites that plot as volcanic arc or syncollisional granites on tectonic discrimination diagrams. The Looking Glass, Pink Beds, and Round Mountain plutons were dated using U-Pb SHRIMP zircon geochronology, and their ages are 333 + 16 Ma, 371.3 + 4.2 Ma, and 342.5 + 2.4 Ma, respectively. Zircon saturation temperature estimates for these plutons, and a Whitney and Stormer two-feldspar estimate for the Round Mountain pluton, indicate that they intruded at 700-800° C. Whole-rock geochemistry was used to constrain the origin of amphibolites and hornblende gneisses around the Toxaway dome. One sample was a metabasalt with MORB composition, like other eastern Blue Ridge samples. Two other samples have a metasedimentary protolith . Migmatitic aureoles found in the amphibolite facies rocks around the Whiteside, Looking Glass, and Horseshoe Rock plutons are syn-intrusional and represent a zone of contact metasomatism. The new pluton ages constrain the regional deformation history. At least 6 deformations are recognized in the eastern Blue Ridge. Dominant regional foliation is traditionally attributed to the second event (~466 Ma). However, foliations measured within all plutons are identical to foliations measured in the surrounding rock, indicating that foliations had to form after the youngest pluton intruded (~333 Ma), and that Alleghanian deformation was dominant in this region. These observations do not explain cross-cutting relationships observed around older plutons and raise new questions about southern Appalachian tectonics.

The Far-Offset Active-Source Imaging of Mantle (FAIM) experiment was conducted along an 800-km-long transect in the Western Atlantic to study the evolution of 108-157 m.y. lithosphere. The main transect (Line 1) crosses a transition from slow (13-14 mm/yr in half rate) to ultra-slow (~8 mm/yr) paleo spreading rates, and thus represents an ideal setting to study spreading-rate dependent processes as expressed in preserved lithospheric structure. This thesis presents results of four analysis efforts along this transect. We present a crustal model based on seismic refraction and wide-angle traveltime modeling, we extend the crustal model to an upper lithosphere density model using gravity constraints, we constrain Poissons ratio in oceanic Layer 3 using converted shear-wave phases, and we consider regional lithospheric structure by analysis of geoid/topography ratios. The crustal model indicates that a transition in crustal thickness accompanies the spreading-rate change, with the crust produced at slow rates being 1.0-1.5 km thinner. The gravity modeling shows that a density model can be constructed that simultaneously satisfies observed gravity, seismic constraints on crustal thickness, and our expectation of isostacy if ~1.3 km of low-density material is distributed into the upper 30-60 km of the mantle. This amount of material (~1.3 km) roughly equals the difference in thickness between slow and ultra-slow spreading crust, suggesting that that the thinner crust formed during very slow spreading arises due to melt retention in the mantle rather than decreased mantle melting. Modeling of mode-converted S-wave phases reveals a uniform of Poissons ratio (~0.27) in the lower crust. Along with the observation of sharp crust/mantle boundary, this result suggests that crust along the FAIM transect is primarily melt-derived igneous crust. Geoid versus topography relationships along Line 1 and nearby parallel tracks show abrupt changes that may originate from lateral changes in mantle density, possibly in response to the transition from slow to ultra-slow spreading. This type of observation may enable us to extend our inferences to a more regional scale.

With a rapid increase in information capacity of Internet access, high-speed, highly-efficiency, and cost-effectiveness laser source for optical fiber communication is required. High-speed 25Gb/s directly modulated laser is essential of this communication range, because of its simple structure, direct-modulation characteristics, low cost, and integration capability for wavelength division multiplexing (WDM) system, and moreover, it can achieved 100Gb/s data transmission by four channel module system. In this work, data modulation speed of 25Gb/s direct modulation DFB laser has been achieved. By employing high-speed coplanar waveguide structure with semi-insulating substrate, high-speed with f3dB > 20GHz has been demonstrated. By the electrical reflection measurement, it confirmed that the high-speed direction modulation can be realized through reduction of electrical parasitics. The laser chips is measured under continuous-wave mode at room temperature. In 1300nm and 1550nm wavelength device, slope efficiency obtained by taper fiber coupled of 0.045 and 0.07mW/mA respectively, output power up to 2.73 and 3.96mW/facet at 60mA. The Side Mode Suppression Ratio was greater than 35dB. 3dB bandwidth of greater than 16GHz and 20.5GHz, relaxation oscillation frequency of 12GHz and 16.6GHz. Finally, clearly back-to-back 25Gb/s eye diagram and error-floor-free performance were obtained.