In exploration seismology, seismic waves are emitted into the structurally complex Earth. Its response, consisting of a mixture of arrivals including primary reflections, conversions, multiples, and transmissions, is used to infer the internal structure and properties. Waves that interact multiple times with the inhomogeneities in the medium probe areas of the subsurface that are sometimes inaccessible to singly scattered waves. However, these contributions are notoriously difficult to use for imaging because multiple scattering turns out to be a highly nonlinear process. Conventionally, imaging algorithms assume singly scattered energy dominates data. Hence these require that energy that scatters more than once is attenuated. The principal focus of this thesis is to incorporate the effect of complex nonlinear scattering in the construction of subsurface elastic images. Reciprocity theory is used to establish an exact relation between the full recorded data and the local (zero-offset, zero-time) scattering response in the subsurface which constitutes our image. Fully nonlinear, elastic imaging conditions are shown to lead to better illumination, higher resolution and improved amplitudes in pure-mode imaging. Strikingly it is also observed that when multiple scattering is correctly handled, no converted-wave energy is mapped to any image point. I explain this result by noting that conversions require finite time and space to manifest. The construction of wavefield propagators (Green’s functions) that are used to extrapolate recorded data from the surface to points in the Earth’s interior is a crucial component of any imaging technique. Classical approaches are based on strong assumptions about the propagation direction of recorded data, and their polarization; preliminary steps of wavefield decomposition (directional and modal) are required to extract upward propagating waves at the recording surface and separate different wave modes. These algorithms also generally fail to explain the trajectories of multiply scattered and converted waves, representing a major problem when constructing nonlinear images as we do not know where such energy interacted with the scatterers to be imaged. A secondary aim of this thesis is to improve on the practice of wavefield extrapolation or redatuming by taking advantage of the different nature of multi-component data compared with single-mode acoustic data. Two-way representation theorems are used to define novel formulations in elastic media which allow both up- and downward propagating fields to be back-propagated correctly without ambiguity in the direction, and such that no cross-talk between wave modes is generated. As an application of directional extrapolation, the acoustic counterpart of the new approach is tested on an ocean-bottom cable field dataset acquired over the Volve field, North Sea. Interestingly, the process of redatuming sources to locations beneath a complex overburden by means of multi-dimensional deconvolution also requires preliminary wavefield separation to be successful: I propose to use the two-way convolution-type representation as a way to combine full pressure and particle velocity recordings. Accurate redatumed wavefields can then be obtained directly from multi-component data without separation. Another major challenge in seismic imaging is to construct detailed velocity models through which recorded data will be extrapolated. Nowadays the information contained in the extension of subsurface images along either the time or space axis is commonly exploited by velocity model building techniques acting in the image domain. Recent research has shown that when both extensions are taken into account, it is possible to estimate the data that would have been recorded if a small, local seismic survey was conducted around any image point in the subsurface. I elaborate on the use of nonlinear elastic imaging conditions to construct such so-called extended image gathers: missing events, incorrect amplitudes, and spurious energy generated from the use of only primary arrivals are shown to be mitigated when multiple scattering is included in the migration process. Finally, having access to virtual recordings in the subsurface is also very useful for target-oriented imaging applications. In the context of one-way representation, I apply the novel methodology of Marchenko redatuming to the Volve field dataset as a way to unravel propagation effects in the overburden structure. Constructed wavefields are then used to synthesize local, subsurface reflection responses that are only sensitive to local heterogeneities, and detailed images of target areas of the subsurface are ultimately produced. Overall the findings of this thesis demonstrate that, while incorporating multiply scattered waves as well as multi-component data in imaging may be not a trivial task, such information is vital for achieving high-resolution and true-amplitude seismic imaging.

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Reed-Solomon codes are a well known family of error-correcting codes with many good properties. However, they require a finite field to operate, limiting the alphabet size to a prime power. In this work, we build a weaker algebraic structure which supports alphabet of any integer size and requires only standard addition, multiplication and division to implement. Then we study a family of error-correcting codes based on matrix multiplication over this structure. We also adapt the Reed-Solomon code principle on this code family and study its properties. We prove and verify experimentally that while a random code of this family has high distance, the Reed-Solomon adaptation fails to perform well. 1

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The IEEE standard of decimal floating-point arithmetic was officially released in 2008. The new decimal floating-point (DFP) format and arithmetic can be applied to remedy the conversion error caused by representing decimal floating-point numbers in binary floating-point format and to improve the computing performance of the decimal processing in commercial and financial applications. Nowadays, many architectures and algorithms of individual arithmetic functions for decimal floating-point numbers are proposed and investigated (e.g., addition, multiplication, division, and square root). However, because of the less efficiency of representing decimal number in binary devices, the area consumption and performance of the DFP arithmetic units are not comparable with the binary counterparts. IBM proposed a binary fused multiply-add (FMA) function in the POWER series of processors in order to improve the performance of floating-point computations and to reduce the complexity of hardware design in reduced instruction set computing (RISC) systems. Such an instruction also has been approved to be suitable for efficiently implementing not only stand-alone addition and multiplication, but also division, square root, and other transcendental functions. Additionally, unconventional number systems including digit sets and encodings have displayed advantages on performance and area efficiency in many applications of computer arithmetic. In this research, by analyzing the typical binary floating-point FMA designs and the design strategy of unconventional number systems, ``a high performance decimal floating-point fused multiply-add (DFMA) with redundant internal encodings" was proposed. First, the fixed-point components inside the DFMA (i.e., addition and multiplication) were studied and investigated as the basis of the FMA architecture. The specific number systems were also applied to improve the basic decimal fixed-point arithmetic. The superiority of redundant number systems in stand-alone decimal fixed-point addition and multiplication has been proved by the synthesis results. Afterwards, a new DFMA architecture which exploits the specific redundant internal operands was proposed. Overall, the specific number system improved, not only the efficiency of the fixed-point addition and multiplication inside the FMA, but also the architecture and algorithms to build up the FMA itself. The functional division, square root, reciprocal, reciprocal square root, and many other functions, which exploit the Newton's or other similar methods, can benefit from the proposed DFMA architecture. With few necessary on-chip memory devices (e.g., Look-up tables) or even only software routines, these functions can be implemented on the basis of the hardwired FMA function. Therefore, the proposed DFMA can be implemented on chip solely as a key component to reduce the hardware cost. Additionally, our research on the decimal arithmetic with unconventional number systems expands the way of performing other high-performance decimal arithmetic (e.g., stand-alone division and square root) upon the basic binary devices (i.e., AND gate, OR gate, and binary full adder). The proposed techniques are also expected to be helpful to other non-binary based applications.

Chronic infection with P. aeruginosa is expected in patients with cystic fibrosis (CF), but the ability to delay, prevent, or better manage infection with multiply-resistant P. aeruginosa (MRPA) can potentially increase quality of life and extend survival. The Texas Children’s Hospital CF Care Center has identified an endemic MRPA strain (dominant clone), and this study aimed to identify risk factors for acquisition of the clone as well as determine differences in patient outcome associated with subsequent infection with the clone. The study included 71 patients with CF with documented MRPA infection. Designation of patients as members of the dominant clone or a non-dominant clone group was based on molecular typing by rep-PCR of MRPA isolates from respiratory cultures. Patient data was collected from Port CF, the national patient registry of the CF Foundation. Patient demographic information and clinical parameters prior to MRPA infection were analyzed by logistic regression as potential risk factors. Differences in patient outcome including change in BMI, change in FEV1, and hospitalization rate were evaluated by MANOVA. Recent hospitalization (< 90 days) was a statistically significant (p = 0.035) risk factor for acquisition of the dominant clone. Patients hospitalized < 90 days prior to MRPA diagnosis were four times more likely to be infected with the dominant clone, and patients hospitalized 91-180 days prior were almost three times more likely. Increased hospitalization rates were seen in the dominant clone group both pre- (11 more days/year) and post-infection (14 more days/year) as compared to the non-dominant clone group. Patients infected with the endemic strain exhibited poorer outcomes in terms of nutritional status (3.73% decrease/year in BMI %ile) and lung function (3.7% decrease/year in FEV1 %ile). Significant overlap in hospitalization episodes of patients known to be infected with the dominant clone and patients subsequently infected with the dominant clone was observed. Recent hospitalization was a significant risk factor for infection with the dominant MRPA clone, and following infection, patients infected with the endemic strain exhibited declines in nutritional status and lung function and increased hospitalization rates. The results suggest potentially increased virulence and transmissibility of the endemic MRPA strain.

Este trabalho trata de estimativas inferiores para o primeiro autovalor de Dirichlet para dom nios multiplamente conexos contidos em variedades riemannianas. Essas estimativas consideram o supremo da curvatura seccional da variedade e a curvatura do bordo do domínio. Para obter os resultados, usa-se uma estimativa C0 para solucões da equação de Poisson. / Lower bounds for the rst Dirichlet eigenvalue are presented. We consider multiply connected domains in riemannian manifolds. The estimates are obtained using hypothesis on the supremum of the manifold's sectional curvature and on the domain's boundary curvature. C0 estimates for solutions of Poissons equation are used to prove the results.

abstract: In the daily life of an individual problems of varying difficulty are encountered. Each problem may include a different number of constraints placed upon the problem solver. One type of problem commonly used in research are multiply-constrained problems, such as the compound remote associates. Since their development they have been related to creativity and insight. Moreover, research has been conducted to determine the cognitive abilities underlying problem solving abilities. We sought to fully evaluate the range of cognitive abilities (i.e., working memory, episodic and semantic memory, and fluid and crystallized intelligence) linked to multiply-constrained problem solving. Additionally, we sought to determine whether problem solving ability and strategies (analytical or insightful) were task specific or domain general through the use of novel problem solving tasks (TriBond and Location Bond). Results indicated that multiply-constrained problem solving abilities were domain general, solutions derived through insightful strategies were more often correct than analytical, and crystallized intelligence was the only cognitive ability that provided unique predictive value. / Dissertation/Thesis / Masters Thesis Psychology 2019

In digital signal processing and multimedia applications, floating-point(FP) multiplication and addition are the most commonly used operations. In addition, FP multiplication operations are frequently followed by the FP addition operations. Therefore, in order to achieve high performance and low cost, multiplication and addition are usually combined into a single unit, known as the FP Multiply-Add Fused (MAF). On the other hand, the mobile devices nowadays are rapidly developing. For this kind of devices, performance and power sustainability have to become the major trend in the research area. As a result, the mechanisms to reduce energy consumption become more important. Therefore, we propose a multi-mode FP MAF based on the concept of iterative multiplication and truncated addition, to achieve different operating modes with different errors. This MAF, with a total of seven modes, includes three modes for the FP multiply-accumulate operations, two modes for single FP multiplication operation and single FP addition operation, respectively. FP multiply-accumulate operations provide three modes to user, and this three modes have 0%, 0.328% and 1.107% of error. The 0% error is the same with the standard IEEE754 single-precision FP Multiply-Add Fused operations. For FP multiplication and FP addition operations, the proposed MAF allows users to choose two kinds of error modes, which are 0%, 0.328% error for FP multiplication and 0%, 0.781% error for FP addition. The 0% error is the same with the standard IEEE754 single-precision floating-point operations. When compared with the standard IEEE754 single-precision FP MAF, the proposed multi-mode FP MAF architecture has 4.5% less area and increase about 22% delay to achieve the effect of multi-mode. To demonstrate the power efficiency of proposed FP MAF, it is used to perform the operations of FP MAF, FP multiplication, and FP addition in the application of RGB to YUV format conversion. Experimental results show that, the proposed multi-mode FP MAF can significantly reduce power consumption when the modes with error are adopted.