Bouguer gravity anomalies at 1870 locations on the central Piedmont of Virginia from 37° 37' N to 37° 52' N and 77° 44' W to 78° 23' W display patterns of variation produced by upper crustal density contrasts and thickening of the crust in a WNW direction. No other deep sources are evident. Upper crustal density contrasts are associated with rock units known from geologic mapping. ‘The subsurface distribution of these rock units interpreted from seismic reflection data was confirmed by measured variations in gravity. A two-dimensional model analysis indicates the following average in situ density values for the principal formations: Arvonia Formation-2.77 gm/cc, Columbia Granitoid-2.75 gm/cc (tonalite) and 2.73 gm/cc (pegmatite), Chopawamsic Volcanics- 2.77 gm/cc (felsic units), and 2.79 gm/cc (mafic units}, Catoctin/ Lynchburg-2.815 gm/cc, Maidens Gneiss-2.775 gm/cc, Grenville Basement- 2.71 gm/cc. Gravity and seismic data are consistent with the existence of a major thrust fault at depths between 9 km and 16 km that separates Grenville Basement rocks from younger Catoctin/Lynchburg rocks. The slight eastward dip of this thrust fault beneath the western part of the area increases significantly east of 78° 05' W. Gravity anomalies suggest the existence of several mafic inclusions within the Columbia Granitoid that were not identified by geologic mapping. / Master of Science

This thesis estimates the impact of non-tariff measures (NTMs) notified by the importing countries on agricultural trade. The non-tariff measures constitute the technical measures notified under the SPS and TBT agreements and the non-technical measures to trade. Two approaches are used; the inventory approach and the econometric approach which makes use of the gravity model. The inventory results suggest that African countries face more restrictions on their exports than what they impose on their imports. Also, Uganda, Senegal and Mali are among the top twenty most affected importers. The empirical results suggest that the impact of the overall group on non-tariff measures is ambiguous but when measures are disaggregated into technical and non-technical measures, the results show that the technical measures promote agricultural trade and that the non-technical measures restrict trade. Also, imports of industrialized nations from fellow industrialized nations are promoted by the technical measures but are restricted by non-technical measures, while those from non-industrialized countries are affected negatively by both technical and non-technical measures. Out of the five regions considered, Africa faces the largest negative impact by both technical and non-technical measures. / Master of Science

Studies have shown that composition and L2 writing teachers give different scores (Golombek, Weigle, Boldt, & Valsecchi, 2003) and focus on different features (Brown, 1991) when assessing student writing, which is assumed to be due to the differences in their background and training (Santos, 1992; Atkinson & Ramanathan, 1995). Error gravity is thought to be one reason why composition and L2 writing teachers give different scores (Rifkin & Roberts, 1995). Common methods for examining error gravity were to analyze scores and responses given by the raters and to have raters reflect on the rating process and analyze their responses. Only one study had used eye-tracking methodology to explore the raters’ reading behaviors (Eckstein, Briney, Chan & Blackwell, 2018). The current study built on Eckstein et al.’s study to examine how composition and L2 writing teachers rate grammar errors differently. The researchers identified three native-like errors and three nonnative-like errors and introduced them into eight paragraphs written by students in a first-year composition class. The researchers asked composition and L2 writing teachers to read and assess the eight paragraphs while an eye-tracker measured their eye-movements. We assume that what raters look at while assessing the paragraphs reflects what they are cognitively processing (Rayner, 1998). The results indicate that composition and L2 writing teachers assign significantly different scores to grammar (L2 writing teachers assign higher scores), yet their reading behaviors are similar. This indicates that teachers with different backgrounds do not process grammar errors differently, but rather reach different scores based on other differences.

A prototype reinforced concrete moment frame representative of low-rise office buildings in the Central and Eastern United States from the 1950s-1970s was designed and selected for evaluation under seismic loads. A plane frame specimen from the prototype was incorporated into the design of a test-bed of four full-scale, side-by-side nominally identical structures that could be evaluated independently. The testing of the first frame serves as the topic of this dissertation. The specimen was two bays x two stories x 9-ft. wide. A new method for testing full-scale structures under seismic loads was proposed that used a hydraulic linear inertial shaker (LIS) to impart seismic loads. The response of the structure was monitored using 155 strain gages, 38 linear variable differential transformers, six string potentiometers, and 42 accelerometers. The response of the frame to a series of 25 load histories using the nees@UCLA LIS was marked by gradual structural softening and minimal yielding of the steel reinforcing throughout the structure. At a first interstory drift of 1.5% some yielding of the reinforcing bars was measured. Between 1.5% and 2% first interstory drift, a global sway mechanism formed when the failure of a splice at the base of the first story west column led to a cascading set of failures within other first-story column splices. The experimental behavior suggests previous scaled testing of similar structures may have inadequately represented the vulnerability column splices. The design of the test-bed, response of the structure to seismic loads, qualitative evaluation of the test method, and implications on future research are discussed.

The Gravity Recovery and Climate Experiment (GRACE) is a joint National Aeronautics and Space Administration / Deutsches Zentrum für Luftund Raumfahrt (NASA/DLR) mission to map the time-variable and mean gravity field of the Earth, and was launched on March 17, 2002. The nature of the gravity field inverse problem amplifies the noise in the data that creeps into the mid and high degree and order harmonic coefficients of the earth's gravity fields for monthly variability, making the GRACE estimation problem ill-posed. These errors, due to the use of imperfect models and data noise, are manifested as peculiar errors in the gravity estimates as north-south striping in the monthly global maps of equivalent water heights. In order to reduce these errors, this study develops a methodology based on Tikhonov regularization technique using the L-curve method in combination with orthogonal transformation method. L-curve is a popular aid for determining a suitable value of the regularization parameter when solving linear discrete ill-posed problems using Tikhonov regularization. However, the computational effort required to determine the L-curve can be prohibitive for a large scale problem like GRACE. This study implements a parameter-choice method, using Lanczos bidiagonalization that is a computationally inexpensive approximation to L-curve called L-ribbon. This method projects a large estimation problem on a problem of size of about two orders of magnitude smaller. Using the knowledge of the characteristics of the systematic errors in the GRACE solutions, this study designs a new regularization matrix that reduces the systematic errors without attenuating the signal. The regularization matrix provides a constraint on the geopotential coefficients as a function of its degree and order. The regularization algorithms are implemented in a parallel computing environment for this study. A five year time-series of the candidate regularized solutions show markedly reduced systematic errors without any reduction in the variability signal compared to the unconstrained solutions. The variability signals in the regularized series show good agreement with the hydrological models in the small and medium sized river basins and also show non-seasonal signals in the oceans without the need for post-processing. / text

The Bouguer correction using a mean sea level reduction datum compensates the gravitational effect of the mass of the terrain above sea level. This correction generally results in long -wavelength Bouguer gravity anomalies if the mass of the terrain is isostatically compensated. These anomalies correlate with regional elevations, especially in areas with significant regional variations in elevation, such as western North America. The adverse effect of this correlation is that other anomalies of potential interest in a tectonic or geologic analysis may be overshadowed. To circumvent this problem in an analysis of gravity in Arizona, a residual Bouguer gravity anomaly map has been constructed for the state in which a trend surface of the elevation is used as the reduction datum in the Bouguer correction. Elevation values from topographic maps and not gravity station elevations have been used to prepare the regional elevation datum because station elevations do not adequately sample the range in elevations. Small- and large-wavelength residual Bouguer gravity anomalies and trends of anomalies are brought out more clearly by the residual Bouguer gravity anomaly map than by previous gravity maps. The most prominent features in the residual anomalies are a strong gravity gradient 50 km wide striking west -northwest across southern Arizona and a large wavelength residual Bouguer gravity anomaly low in the Coconino Plateau of northwest Arizona . The long-wavelength residual Bouguer gravity anomalies reflect lateral density variations in the crust and mantle that may be related to lateral temperature variations.

Einstein's field equations are a system of ten partial differential equations. For a special class of spacetimes known as Gowdy spacetimes, the number of equations is reduced due to additional structure of two dimensional isometry groups with mutually orthogonal Killing vectors. In this thesis, we focus on a particular model of Gowdy spacetimes known as the polarized T3 model, and provide an explicit solution to Einstein's equations.

In orbit, finding the "bottom" of your coffee cup is a non-trivial task. Subtle forces often masked by gravity influence the containment and transport of fluids aboard spacecraft, often in surprising non-intuitive ways. Terrestrial experience with capillary forces is typically relegated to the micro-scale, but engineering community exposure to large length scale capillary fluidics critical to spacecraft fluid management design is low indeed. Low-cost drop towers and fast-to-flight International Space Station (ISS) experiments are increasing designer exposure to this fresh field of study. This work first provides a wide variety of drop tower tests that demonstrate fundamental and applied capillary fluidics phenomena related to liquid droplets and gas bubbles. New observations in droplet auto-ejection, droplet combustion, forced jet combustion, puddle jumping, bubble jumping, and passive phase separation are presented. We also present the Capillary Beverage Experiment on ISS as a fun and enlightening application of capillary fluidics where containment and passive control of poorly wetting aqueous capillary systems is observed. Astronauts are able to smell their coffee from the open stable container while still drinking in an Earth-like manner with the role of gravity replaced by the combined effects of surface tension, wetting, and special container geometry. The design, manufacture, low-g demonstrations, and quantitative performance of the Space Cups are highlighted. Comparisons of numerical simulations, drop tower experiments, and ISS experiments testify to the prospects of new no-moving-parts capillary solutions for certain water-based life support operations aboard spacecraft.

Um dos sistemas utilizados na geofísica de exploração são os sistemas gravimétricos aerotransportados. Estes sistemas, no entanto,necessitam parametrizações para aferir a qualidade dos levantamentos executados. Com a introdução da aerogravimetria no Brasil, através do levantamento da Bacia do Parnaíba, foi necessário desenvolver uma área de testes para aferição destes equipamentos. Em 2004 foram implantadas 166 estações gravimétricas na região da pista de teste, localizada no município de Tietê, SP. Devido ao crescente interesse na utilização do tensor gradiente da gravidade no estudo de localização de jazidas minerais tornou-se necessário gerar modelos geofísicos mais detalhados com o objetivo de localizar alvos rasos em subsuperfície. Com a finalidade de melhorar o limite de resolução dos testes realizados utilizando diferentes sistemas gravimétricos aerotransportados foi realizado um adensamento da malha gravimétrica da pista teste de Tietê. Para tanto, foram implementadas novas estações gravimétricas, distribuídas em diferentes espaçamentos, estabelecendo a primeira pista brasileira para calibração de aerogravimetria escalar e sistemas de aerogradiometria gravimétrica 3D. / Airborne gravimetric systems are among geophysical systems applied to expl oration. These systems rely on parametrization to gauge the quality of surveys. With the introduction of airborne gravity surveys in Brazil, with the Parnaiba Basin survey, demand for an equipment calibration lane arose.In 2004, 166 gravity stations were set in the test lane area located in the municipality of Tietê, SP. The need for more detailed geophysical models capable of identifying shallow targets resulted from surging interest in applying gravity gradiometric tensor to locate mineral deposits. The Tietê test lane was densified in order to improve the resolution limitation in tests of a range of airborne gravity systems. To achieve that, new gravity stations were set with different spacing. This stablished the first Brazilian calibration lane for scalar gravimetry and 3D airborne gravity gradiometry systems.

O estudo de teorias de calibre não-Abelianas fortemente acopladas, em especial de aspectos térmicos e fora do equilíbrio, é um problema central para a compreensão da Cromodinâmica Quântica (Quantum Chromodynamics - QCD) - em particular, para entender a evolução do Plasma de Quarks e Glúons (Quark-Gluon Plasma- QGP). A técnica mais promissora, QCD na rede, obteve sucesso ao tratar de fenômenos no vácuo e em equilíbrio térmico, como espectros e termodinâmica, mas enfrenta desafios consideráveis ao lidar com fenômenos fora do equilíbrio. Uma ferramenta adaptada para lidar com problemas envolvendo plasmas fortemente acoplados em tempo real é a dualidade gauge/gravity, que mapeia uma Teoria Quântica de Campos (Quantum Field Theory - QFT) fortemente acoplada em d dimensões em uma teoria de gravitação em d + 1 dimensões, a qual, de modo geral, é mais fácil de ser resolvida. Nesta tese, estudamos diversas aplicações da dualidade gauge/gravity em teorias não-Abelianas fortemente acopladas que modelam qualitativamente o QGP. Nós estudamos o cálculo holográfico do potencial entre um par quark-antiquark pesado (QQ) para dipolos QQ estáticos e se movendo com relação ao plasma, apresentando um formalismo geral para o cálculo da parte real e imaginária para uma grande classe de teorias gravitacionais duais. Um estudo da massa de Debye holográfica, baseado no maior comprimento de correlação de operadores ímpares por transformações de CT, foi empreendido, com aplicações em modelos bottom-up que reproduzem a termodinâmica da teoria de Yang-Mills SU(Nc) pura e da QCD. Para estes modelos, também calculamos vários coeficientes de transporte associados com o transporte de cargas no plasma, como a condutitividade elétrica, a constante de difusão de carga e coeficientes de transporte associados a uma teoria de hidrodinâmica relativística de segunda ordem. / The study of strongly coupled non-Abelian gauge theories, especially concerning their thermal and non-equilibrium aspects, is a central problem for understanding Quantum Chromodynamics (QCD) - in particular, to understand the evolution of the Quark-Gluon Plasma (QGP). The most successful approach, lattice QCD, succeeds in dealing with vacuum and equilibrium phenomena, such as spectra and thermodynamics, but faces a considerable challenge when it comes to with non-equilibrium phenomena. A tool adapted to deal with real time problems in strongly coupled plasmas is the gauge/gravity, which maps a strongly coupled d dimensional Quantum Field Theory (QFT) to a d + 1 dimensional theory of gravity, which, in general, is easier to solve. In this thesis, we study several applications of the gauge/gravity duality to strongly coupled non-Abelian theories which model qualitatively the QGP. We deal with the holographic evaluation of the heavy quark-antiquark (Q Q) potential for static and moving QQ dipoles, presenting a general formalism for the computation of the real and imaginary parts for a large class of dual theories of gravity. A study of the holographic Debye mass, based on the largest screening length of CT-odd operators, is pursued, with applications on bottom-up holographic models that reproduce the thermodynamics of pure SU(Nc) Yang-Mills theory and QCD. For these models, we also compute several transport coefficients associated with charge transport in the plasma, such as the electric conductivity, the charge diffusion constant, and transport coefficients associated with a theory of second order relativistic hydrodynamics.