This research is primarily focused on developing potential applications for microwaveinduced thermoacoustic tomography and correcting for image degradations caused by acoustic heterogeneities. Microwave-induced thermoacoustic tomography was first used to verify the feasibility of noninvasively detecting the coagulated damage based on different dielectric properties between normal tissue and lesion treated with high intensity focused ultrasound. Good image contrasts were obtained for the lesions. A comparison of the size of the lesion measured with microwave-induced thermoacoustic tomography and the size measured by a gross pathologic photograph was presented to verify the effectiveness the proposed method. Clinical data for breast tumors were also collected to verify the feasibility of using microwave-induced thermoacoustic tomography in breast cancer imaging. Next, the effects of acoustic heterogeneities on microwave-induced thermoacoustic tomography in weakly refractive medium were investigated. A correction method based on ultrasonic transmission tomography was proposed to correct for the image distortion. Numerical simulations and phantom experiments verify the effectiveness of this correction method. The compensation is important for obtaining higher resolution images of small tumors in acoustically heterogeneous tissues. Finally, the effects of the highly refractive skull on transcranial brain imaging were studied. A numerical method, which considered wave reflection and refraction at the skull surfaces, was proposed to compensate for the image degradation. The results obtained with the proposed model were compared with the results without considering the skull-induced distortion to evaluate the skull-induced effects on the image reconstruction. It was demonstrated by numerical simulations and phantom experiments that the image quality could be improved by incorporating the skull shape and acoustic properties into image reconstruction. This compensation method is important when the thickness of skull cannot be neglected in transcranial brain imaging.

No description available.

A tradução de Sérgio Milliet dos Essais de Michel de Montaigne para o português brasileiro envolve um trabalho de leitura, interpretação e escritura em várias frentes: estilística, retórica, linguística, antropológica, histórica, etc. O objetivo deste trabalho é identificar como foram traduzidos os pontos de inflexão nos quais os discursos do Outro aparecem no de Montaigne. O fio condutor do estudo pelo texto montaigneano representado pelo o paratexto páginas de rosto, prefácios e notas das edições francesas e das edições usadas na tradução leva, em torno da noção de reformulação, às heterogeneidades enunciativas e à tradução da escritura. O percurso traçado faz com que a reformulação, no sentido amplo da comunicação, seja pensada como uma noção operatória na abordagem de questões discursivas. O princípio que norteia o trabalho é baseado numa análise do discurso que considera o interdiscurso como origem de todo discurso e a heterogeneidade enunciativa como constitutiva da linguagem. Assim, a leitura/interpretação dos capítulos leva em conta a maneira como alguns traços da heterogeneidade a citação e a ironia se realizam na escritura do texto de Montaigne e nas traduções. A partir da observação empírica das traduções em francês moderno e em português brasileiro, nota-se que esses traços, diferentemente reformulados, trazem para dentro dos novos textos características que podem ser atribuídas às representações, sociais e individuais, dos próprios tradutores. / The Brazilian Portuguese translation of the Essais de Michel de Montaigne by Sérgio Milliet involves an effort of reading, interpretation and writing in many ways: stylistic, rhetoric, linguistic, anthropological, historical, etc. This work aims at the identification of how those points of inflexion in which the Others discourse shows up in Montaignes discourse were translated. The paratextual title pages, prefaces and notes of the French editions were the connecting thread through Montaignes texts to the enunciative heterogeneities and to the translation. The reformulation is, in the broad sense of communication, an operating notion in the approach of discourses questions. The research is based on the discourse analysis, which considers the interdiscourse as the origin of all discourse and the heterogeneity as a constructive element of language. The reading/interpretation of chapters takes into account the heterogeneities citation and irony that appear in Montaignes writing and in the translations. From the empirical observation of translations to modern French and to Brazilian Portuguese we noticed that these features, formulated in a different way, bring to the new texts some characteristics that may be imputed to the social and individual representations of the translators themselves.

acase@tulane.edu / Advanced omics technologies have been generating abundant multi-ethnic multi-omics data, including DNA sequences, methylations, gene expressions, and copious clinical traits. Such big data pose unprecedented challenges due to the high complexity of heterogeneous networks between biomarkers. Heteroscedasticity (aka, dispersion heterogeneity of trait residuals) is a common phenomenon in multi-omics data mining. It can be caused by interactions such as gene×gene, gene×enviroment, linkage disequilibrium (LD) between marker loci, and pleiotropic traits as well. Especially, it occurs in the data mining of the multi-omics data of admixed individuals subjects due to broad admixture LD and gene×ancestry interactions. Meanwhile, it can be induced by background confounders, e.g., population structure, cryptic relatedness, polygenetic effects, and correlations between residuals of multiple traits. However, existent univariate and multivariate methods neglect all the high-order effects of both test biomarkers and background confounders. This dissertation contributes systematic harmonious signal augmentation methods with applications for distilling high-order information from multiethnic DNA sequences to microarrays. In Chapter I, we proposed a novel harmonious signal augmentation schemes in single-based association tests. The harmonious single-based association test (HSAT) is more powerful then existent single-based methods in both simulations and real data application. In Chapter II we put forth harmonious gene-based association tests (HGAT) to incorporate high-order effects. Within a gene, the importance of a test variant is measured by the signal of marker-wise high-order effects. Leveraging high-order effects of genetic variants has proven to improve power for identifying susceptive genes. By extensive simulations under published designs, the proposed method properly controlled type I error rates and appeared strikingly more powerful than existent prominent gene-based sequence association methods. We apply HGAT methods in homogeneous population and admixed population. There are two parts in Chapter III, the first part introduced integrating informative mean and variance effects to identify differentially expressed (DE) genes. The second part illustrated the application of harmonious integration of mean and high order effects to identify differentially expressed (DE) genes. In summary, this dissertation demonstrated tremendous potential of explicitly distilling informative higher-order effects in big multiethnic multi-level data mining and offered paradigm applications for integrating high-order information resources while effectively calibrating major heteroscedastic confounders. / 1 / Weiwei Ouyang

acase@tulane.edu / 1 / Weiwei Ouyang

Doctor of Philosophy (PhD) / The glass-transition traverses continuously from liquid to solid behaviour, yet the role of structure in this large and gradual dynamic transition is poorly understood. This thesis presents a theoretical study of the relationship between structure and dynamics in two-dimensional glass-forming alloys, and provides new tools and real-space insight into the relationship at a microscopic level. The work is divided into two parts. Part I is concerned with the role of structure in the appearance of spatially heterogeneous dynamics in a supercooled glass-forming liquid. The isoconfigurational ensemble method is introduced as a general tool for analysing the effect that a configuration has on the subsequent particle motion, and the dynamic propensity is presented as the aspect of structural relaxation that can be directly related to microscopic variations in the structure. As the temperature is reduced, the spatial distribution of dynamic propensity becomes increasingly heterogeneous. This provides the first direct evidence that the development of spatially heterogeneous dynamics in a fragile glass-former is related to spatial variations in the structure. The individual particle motion also changes from Gaussian to non- Gaussian as the temperature is reduced, i.e. the configuration expresses its character more and more intermittently. The ability of several common measures of structure and a measure of structural ‘looseness’ to predict the spatial distribution of dynamic propensity are then tested. While the local coordination environment, local potential energy, and local free volume show some correlation with propensity, they are unable to predict its spatial variation. Simple coarse-graining does not help either. These results cast doubt on the microscopic basis of theories of the glass transition that are based purely on concepts of free volume or local potential energy. In sharp contrast, a dynamic measure of structural ‘looseness’ - an isoconfigurational single-particle Debye-Waller (DW) factor - is able to predict the spatial distribution of propensity in the supercooled liquid. This provides the first microscopic evidence for previous correlations found between short- and long-time dynamics in supercooled liquids. The spatial distribution of the DW factor changes rapidly in the supercooled liquid and suggests a picture of structural relaxation that is inconsistent with simple defect diffusion. Overall, the work presented in Part I provides a real-space description of the transition from structure-independent to structure-dependent dynamics, that is complementary to the configuration-space description provided by the energy landscape picture of the glass transition. In Part II, an investigation is presented into the effect of varying the interparticle potential on the phase behaviour of the binary soft-disc model. This represents a different approach to studying the role of structure in glass-formation, and suggests many interesting directions for future work. The structural and dynamic properties of six different systems are characterised, and some comparisons are made between them. A wide range of alloy-like structures are formed, including substitutionally ordered crystals, amorphous solids, and multiphase materials. Approximate phase diagrams show that glass-formation generally occurs between competing higher symmetry structures. This work identifies two new glass-forming systems with effective chemical ordering and substantially different short- and medium-range structure compared to the glassformer studied in Part I. These represent ideal candidates for extending the study presented in Part I. There also appears to be a close connection between quasicrystal and glass-formation in 2D via random-tiling like structures. This may help explain the experimental observation that quasicrystals sometimes vitrify on heating. The alignment of asymmetric unit cells is found to be the rate-limiting step in the crystal nucleation and growth of a substitutionally ordered crystal, and another system shows amorphous-crystal coexistence and appears highly stable to complete phase separation. The generality of these results and their implications for theoretical descriptions of the glass transition are also discussed.

This study addresses the origin of the combined He-Ne-Ar-Xe noble gas isotopic variation in mantle derived oceanic basalts. High precision heavy noble gas compositions of basalts from the Rochambeau Rift along the Northwestern Lau Basin, the Gakkel Ridge, the Southeast Indian Ridge and the South Atlantic Ridge presented here confirms fundamental differences between the volatile constituents of the depleted mid-ocean ridge basalt (MORB) source and plume sources. We find that the depleted MORB mantle is characterized by systematically lower proportions of Pu-fission derived Xe than the Iceland plume and the Samoan-like plume sampled at the Rochambeau Rift. These two plume sources are associated with low radiogenic \(^{129}Xe/^{130}Xe\) ratios that are not attributable to recycled atmosphere and must sample ancient (4.45 Ga) volatile rich mantle reservoir that experienced a lower degree of mantle processing than the depleted MORB source. I report \(^{128}Xe/^{130}Xe\) ratios in excess with respect to the atmosphere in deeply erupting Gakkel lavas, similar to mantle derived volatiles in natural gas samples. Deconvolution of fission derived xenon isotopes indicate that natural gas samples and the Gakkel MORBs are derived from the same volatile depleted mantle reservoir. The radiogenic He isotopic composition, the low estimated ratio of Pu to U derived xenon isotopes, and the low \(^{129}Xe/^{130}Xe_E\) ratio found in the source of the West Volcanic Zone (WVZ) along the Gakkel Ridge indicates the presence of increased amounts of recycled atmospheric volatiles. I suggest that the low \(^{129}Xe/^{130}Xe\) ratio beneath the WVZ cannot be explained by sampling an ancient (>4.45 Ga) lithospheric mantle component that evolved in isolation from convection throughout Earth's history. Instead, the Xe isotopic composition may be consistent with the presence of subduction derived metasomatizing fluids with atmospheric heavy noble gases trapped in the sub-continental lithospheric mantle sampled along the ridge. Available Ne isotope MORB data and new high precision Ne data presented in this study (including basalts from the East Pacific Rise, the Galapagos Spreading Center, and the Juan de Fuca Ridge) allows me to construct a combined He-Ne isotope distribution and infer first order source mixing systematics in the upper mantle. / Earth and Planetary Sciences

Doctor of Philosophy (PhD) / The glass-transition traverses continuously from liquid to solid behaviour, yet the role of structure in this large and gradual dynamic transition is poorly understood. This thesis presents a theoretical study of the relationship between structure and dynamics in two-dimensional glass-forming alloys, and provides new tools and real-space insight into the relationship at a microscopic level. The work is divided into two parts. Part I is concerned with the role of structure in the appearance of spatially heterogeneous dynamics in a supercooled glass-forming liquid. The isoconfigurational ensemble method is introduced as a general tool for analysing the effect that a configuration has on the subsequent particle motion, and the dynamic propensity is presented as the aspect of structural relaxation that can be directly related to microscopic variations in the structure. As the temperature is reduced, the spatial distribution of dynamic propensity becomes increasingly heterogeneous. This provides the first direct evidence that the development of spatially heterogeneous dynamics in a fragile glass-former is related to spatial variations in the structure. The individual particle motion also changes from Gaussian to non- Gaussian as the temperature is reduced, i.e. the configuration expresses its character more and more intermittently. The ability of several common measures of structure and a measure of structural ‘looseness’ to predict the spatial distribution of dynamic propensity are then tested. While the local coordination environment, local potential energy, and local free volume show some correlation with propensity, they are unable to predict its spatial variation. Simple coarse-graining does not help either. These results cast doubt on the microscopic basis of theories of the glass transition that are based purely on concepts of free volume or local potential energy. In sharp contrast, a dynamic measure of structural ‘looseness’ - an isoconfigurational single-particle Debye-Waller (DW) factor - is able to predict the spatial distribution of propensity in the supercooled liquid. This provides the first microscopic evidence for previous correlations found between short- and long-time dynamics in supercooled liquids. The spatial distribution of the DW factor changes rapidly in the supercooled liquid and suggests a picture of structural relaxation that is inconsistent with simple defect diffusion. Overall, the work presented in Part I provides a real-space description of the transition from structure-independent to structure-dependent dynamics, that is complementary to the configuration-space description provided by the energy landscape picture of the glass transition. In Part II, an investigation is presented into the effect of varying the interparticle potential on the phase behaviour of the binary soft-disc model. This represents a different approach to studying the role of structure in glass-formation, and suggests many interesting directions for future work. The structural and dynamic properties of six different systems are characterised, and some comparisons are made between them. A wide range of alloy-like structures are formed, including substitutionally ordered crystals, amorphous solids, and multiphase materials. Approximate phase diagrams show that glass-formation generally occurs between competing higher symmetry structures. This work identifies two new glass-forming systems with effective chemical ordering and substantially different short- and medium-range structure compared to the glassformer studied in Part I. These represent ideal candidates for extending the study presented in Part I. There also appears to be a close connection between quasicrystal and glass-formation in 2D via random-tiling like structures. This may help explain the experimental observation that quasicrystals sometimes vitrify on heating. The alignment of asymmetric unit cells is found to be the rate-limiting step in the crystal nucleation and growth of a substitutionally ordered crystal, and another system shows amorphous-crystal coexistence and appears highly stable to complete phase separation. The generality of these results and their implications for theoretical descriptions of the glass transition are also discussed.

A tradução de Sérgio Milliet dos Essais de Michel de Montaigne para o português brasileiro envolve um trabalho de leitura, interpretação e escritura em várias frentes: estilística, retórica, linguística, antropológica, histórica, etc. O objetivo deste trabalho é identificar como foram traduzidos os pontos de inflexão nos quais os discursos do Outro aparecem no de Montaigne. O fio condutor do estudo pelo texto montaigneano representado pelo o paratexto páginas de rosto, prefácios e notas das edições francesas e das edições usadas na tradução leva, em torno da noção de reformulação, às heterogeneidades enunciativas e à tradução da escritura. O percurso traçado faz com que a reformulação, no sentido amplo da comunicação, seja pensada como uma noção operatória na abordagem de questões discursivas. O princípio que norteia o trabalho é baseado numa análise do discurso que considera o interdiscurso como origem de todo discurso e a heterogeneidade enunciativa como constitutiva da linguagem. Assim, a leitura/interpretação dos capítulos leva em conta a maneira como alguns traços da heterogeneidade a citação e a ironia se realizam na escritura do texto de Montaigne e nas traduções. A partir da observação empírica das traduções em francês moderno e em português brasileiro, nota-se que esses traços, diferentemente reformulados, trazem para dentro dos novos textos características que podem ser atribuídas às representações, sociais e individuais, dos próprios tradutores. / The Brazilian Portuguese translation of the Essais de Michel de Montaigne by Sérgio Milliet involves an effort of reading, interpretation and writing in many ways: stylistic, rhetoric, linguistic, anthropological, historical, etc. This work aims at the identification of how those points of inflexion in which the Others discourse shows up in Montaignes discourse were translated. The paratextual title pages, prefaces and notes of the French editions were the connecting thread through Montaignes texts to the enunciative heterogeneities and to the translation. The reformulation is, in the broad sense of communication, an operating notion in the approach of discourses questions. The research is based on the discourse analysis, which considers the interdiscourse as the origin of all discourse and the heterogeneity as a constructive element of language. The reading/interpretation of chapters takes into account the heterogeneities citation and irony that appear in Montaignes writing and in the translations. From the empirical observation of translations to modern French and to Brazilian Portuguese we noticed that these features, formulated in a different way, bring to the new texts some characteristics that may be imputed to the social and individual representations of the translators themselves.

No description available.