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A principal via de infecção pelo Vírus da Imunodeficiência Humana (HIV-1) em crianças é a transmissão materno-infantil (TMI). Diversos fatores podem estar associados com a TMI do HIV-1. Acredita-se que indivíduos homozigotos para o alelo CCR5-?32 são resistentes à infecção pelo HIV-1. Considerando que ainda permanece controverso o papel dos mecanismos envolvidos, especificamente o de polimorfismos de genes associados à infecção do HIV-1, este estudo avalia a influência da deleção do gene CCR5 na TMI da infecção pelo HIV-1. Foram avaliadas 82 duplas de mães e filhos, sendo 56 duplas em que não ocorreu a TMI e 26 em que ocorreu a TMI do HIV-1. Na presente casuística, não detectamos diferenças significantes ao compararmos a presença da deleção do gene CCR5 na TMI, nas duplas de mãe e filhos, mas observamos que há uma predominância da presença da deleção nos filhos não infectados em comparação aos que foram verticalmente infectados. Relativo aos dados socio-demográficos, a utilização da terapia antirretroviral na gestação e parto foram significantemente associados com a proteção da TMI do HIV-1(p= 0,0001 e p= 0,014, respectivamente). Assim, a promoção de intervenções que reduzam a carga viral materna são fundamentais para a redução da TMI do HIV-1. Várias são as estratégias de prevenção da TMI, entretanto, crianças ainda são infectadas, evidenciando-se que ainda há um amplo desafio na sua prevenção. Nesse contexto, a enfermagem pode contribuir com ações que envolvem o pré-natal, parto e puerpério, realizando aconselhamento quanto à realização do teste anti-HIV, utilização de antirretrovirais, promoção e o apoio de práticas ideais de alimentação infantil. / The main via of infection by Human Imunodeficiency Virus (HIV-1) in children is the maternal-infant transmission (MIT). Several factors can be associated to MIT of HIV- 1. It\'s believed that the homozygote individual to the allele CCR5-?32 are resistant to the infection of HIV-1. Considering that the role of the mechanisms involved are still controversial, specifically the one of polymorphism of genes associated to the infection of HIV-1, this study evaluates the influence of deletion of the gene CCR5 in the MIT of the infection by HIV-1. It has been evaluated 82 couples of mothers and children, being 56 couples in which haven\'t occurred MIT and 26 in which have occurred MIT of HIV-1. In the current casuistry, it hasn\'t been detected meaningful differences when compared the presence of deletion of the gene CCR5 in MIT, in mother and children\'s couples, but it has been observed that there is a predominance of the presence of deletion in the not infected children to the ones vertically infected. Related to the social-demographic data, the use of antiretroviral therapy in the gestation and labor was meaningfully associated to the protection of MIT of HIV-1 (p= 0,0001 e p= 0,014, respectively). Therefore, the promotion of interventions that reduce the maternal viral load are fundamental for the reduction of MIT of HIV-1. There are several strategies to prevent the MIT, thus, children are still infected, becoming evident that there is still a wide challenge of its prevention. In this context, the nursing can contribute with actions that involve the prenatal, labor and puerperium, advising about the realization of the test of anti-HIV, the usage of antiretrovials, promotion and support of ideal practices of infant nourishment.

A principal via de infecção pelo Vírus da Imunodeficiência Humana (HIV-1) em crianças é a transmissão materno-infantil (TMI). Diversos fatores podem estar associados com a TMI do HIV-1. Acredita-se que indivíduos homozigotos para o alelo CCR5-?32 são resistentes à infecção pelo HIV-1. Considerando que ainda permanece controverso o papel dos mecanismos envolvidos, especificamente o de polimorfismos de genes associados à infecção do HIV-1, este estudo avalia a influência da deleção do gene CCR5 na TMI da infecção pelo HIV-1. Foram avaliadas 82 duplas de mães e filhos, sendo 56 duplas em que não ocorreu a TMI e 26 em que ocorreu a TMI do HIV-1. Na presente casuística, não detectamos diferenças significantes ao compararmos a presença da deleção do gene CCR5 na TMI, nas duplas de mãe e filhos, mas observamos que há uma predominância da presença da deleção nos filhos não infectados em comparação aos que foram verticalmente infectados. Relativo aos dados socio-demográficos, a utilização da terapia antirretroviral na gestação e parto foram significantemente associados com a proteção da TMI do HIV-1(p= 0,0001 e p= 0,014, respectivamente). Assim, a promoção de intervenções que reduzam a carga viral materna são fundamentais para a redução da TMI do HIV-1. Várias são as estratégias de prevenção da TMI, entretanto, crianças ainda são infectadas, evidenciando-se que ainda há um amplo desafio na sua prevenção. Nesse contexto, a enfermagem pode contribuir com ações que envolvem o pré-natal, parto e puerpério, realizando aconselhamento quanto à realização do teste anti-HIV, utilização de antirretrovirais, promoção e o apoio de práticas ideais de alimentação infantil. / The main via of infection by Human Imunodeficiency Virus (HIV-1) in children is the maternal-infant transmission (MIT). Several factors can be associated to MIT of HIV- 1. It\'s believed that the homozygote individual to the allele CCR5-?32 are resistant to the infection of HIV-1. Considering that the role of the mechanisms involved are still controversial, specifically the one of polymorphism of genes associated to the infection of HIV-1, this study evaluates the influence of deletion of the gene CCR5 in the MIT of the infection by HIV-1. It has been evaluated 82 couples of mothers and children, being 56 couples in which haven\'t occurred MIT and 26 in which have occurred MIT of HIV-1. In the current casuistry, it hasn\'t been detected meaningful differences when compared the presence of deletion of the gene CCR5 in MIT, in mother and children\'s couples, but it has been observed that there is a predominance of the presence of deletion in the not infected children to the ones vertically infected. Related to the social-demographic data, the use of antiretroviral therapy in the gestation and labor was meaningfully associated to the protection of MIT of HIV-1 (p= 0,0001 e p= 0,014, respectively). Therefore, the promotion of interventions that reduce the maternal viral load are fundamental for the reduction of MIT of HIV-1. There are several strategies to prevent the MIT, thus, children are still infected, becoming evident that there is still a wide challenge of its prevention. In this context, the nursing can contribute with actions that involve the prenatal, labor and puerperium, advising about the realization of the test of anti-HIV, the usage of antiretrovials, promotion and support of ideal practices of infant nourishment.

abstract: The experience base of practitioners with expansive soils is largely devoid of directly measured soil suction. This historical lack of soil suction measurement represents an impediment to adoption of modern unsaturated soil engineering to problems of expansive soils. Most notably, soil suction-based analyses are paramount to proper design of foundations in expansive soils. Naturally, the best method to obtain design suction profiles is to perform an appropriate geotechnical investigation that involves soil moisture change-appropriate drilling depths, sampling intervals, and requisite laboratory testing, including suction measurement. However, as practitioners are slow to embrace changes in methodology, specifically regarding the adoption of even relatively simple suction measurement techniques, it has become imperative to develop a method by which the routine geotechnical procedures currently employed can be used to arrive at acceptable approximations of soil suction profiles. Herein, a substitute, or surrogate, for soil suction is presented, such that the surrogate agrees with observed field soil suction patterns and provides estimates of soil suction that are acceptable for use in practice. Field investigations with extensive laboratory testing, including direct suction measurement, are used in development of the soil suction surrogate. This surrogate, a function of water content and routinely measured soil index properties, is then used in estimation of field expansive soil suction values. The suction surrogate, together with existing geotechnical engineering reports, is used to augment the limited existing database of field soil suction profiles. This augmented soil suction profile database is used in development of recommendations for design suction envelopes and design suction profiles. Using the suction surrogate, it is possible to proceed from the beginning to the end of the Suction-Oedometer soil heave/shrinkage analysis without directly measuring soil suction. The magnitude of suction surrogate-based heave estimates is essentially the same as heave estimates obtained using direct soil suction measurements. The soil suction surrogate-based approach, which uses a complete-stress-state approach, considering both net normal stress and soil suction, is an intermediate step towards the adoption of unsaturated soil engineering in expansive soils analyses, wherein direct soil suction measurements are routinely made. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2019

The removal of systematic brightness temperature (Tb) biases is necessary when producing decadal passive microwave data sets for weather and climate research. It is crucial to achieve Tb measurement consistency among all satellites in a constellation as well as to maintain sustained calibration accuracy over the lifetime of each satellite sensor. In-orbit inter-satellite radiometric calibration techniques provide a long term, group-wise solution; however, since radiometers operate at different frequencies and viewing angles, Tb normalizations are made before making intermediate comparisons of their near-simultaneous measurements. In this dissertation, a new approach is investigated to perform these normalizations from one satellite's measurements to another. It uses Taylor's series expansion around a source frequency to predict Tb of a desired frequency. The relationship between Tb's and frequencies are derived from simulations using an oceanic Radiative Transfer Model (RTM) over a wide variety of environmental conditions. The original RTM is built on oceanic radiative transfer theory. Refinements are made to the model by modifying and tuning algorithms for calculating sea surface emission, atmospheric emission and attenuations. Validations were performed with collocated WindSat measurements. This radiometric calibration approach is applied to establish an absolute brightness temperature reference using near-simultaneous pair-wise comparisons between a non-sun synchronous radiometer and two sun-synchronous polar-orbiting radiometers: the Tropical Rain Measurement Mission (TRMM) Microwave Imager (TMI), WindSat (on Coriolis) and Advanced Microwave Scanning Radiometer (AMSR) on Advanced Earth Observing System -II (ADEOSII), respectively. Collocated measurements between WindSat and TMI as well as between AMSR and TMI, within selected 10 weeks in 2003 for each pair, are collected, filtered and applied in the cross calibration. AMSR is calibrated to WindSat using TMI as a transfer standard. Accuracy prediction and error source analysis are discussed along with calibration results. This inter-satellite radiometric calibration approach provides technical support for NASA's Global Precipitation Mission which relies on a constellation of cooperative satellites with a variety of microwave radiometers to make global rainfall measurements.

This dissertation provides a robust radiometric calibration for the TRMM Microwave Imager to correct systematic brightness temperature errors, which vary dynamically with orbit position (time) and day of the year. The presence of a time-varying bias in TMI is confirmed by inter-calibration with WindSat and SSMI. This time varying bias is manifested as a time of day dependent variation of the relative biases between TMI and both WindSat and SSMI. In this dissertation, we provide convincing evidence that this time-varying Tb bias in TMI is caused by variations in the physical temperature of the emissive TMI reflector antenna. This dissertation provides an empirical correction that largely corrects this time-varying bias. The TMI bias is estimated by comparing the 10.7 GHz V-polarization channel observations with RTM Tb predictions, and the Tb correction is applied as a function of orbit time for every day of the one year period. Furthermore, this dissertation provides a qualitative physical basis for the estimated Tb bias patterns and provides conclusive evidence that the empirical correction applied to TMI Tb measurements (both ocean and land) largely corrects the time-varying TMI calibration. This is accomplished by demonstrating that the local time-of-day dependence (in the uncorrected TMI Tb values) is removed in the corrected TMI Tb's.

This dissertation revisits, develops, and documents methods that can be used to calibrate spaceborne microwave radiometers once in orbit. The on-orbit calibration methods discussed within this dissertation can provide accurate and early results by utilizing Calibration Attitude Maneuvers (CAM), which encompasses Deep Space Calibration (DSC) and a new use of the Second Stokes (SS) analysis that can provide early and much needed insight on the performance of the instrument. This dissertation describes pre-existing and new methods of using DSC maneuvers as well as a simplified use of the SS procedure. Over TRMM's 17 years of operation it has provided invaluable data and has performed multiple CAMs over its lifetime. These maneuvers are analyzed to implement on-orbit calibration procedures that will be applied for future missions. In addition, this research focuses on the radiometric calibration of TMI that will be incorporated in the final processing (Archive/Legacy of the NASA TMI 1B11 brightness temperature data product). This is of importance since TMI's 17-year sensor data record must be vetted of all known calibration errors so to provide the final stable data for science users, specifically, climatological data records.

Error characteristics associated with satellite-derived precipitation products are important for atmospheric and hydrological model data assimilation, forecasting, and climate diagnostic applications. This information also aids in the refinement of physical assumptions within algorithms by identifying geographical regions and seasons where existing algorithm physics may be incorrect or incomplete. Examination of relative errors between independent estimates derived from satellite microwave data is particularly important over regions with limited surface-based equipments for measuring rain rate such as the global oceans and tropical continents. In this context, analysis of microwave based satellite datasets from the Tropical Rainfall Measuring Mission (TRMM) enables to not only provide information regarding the inherent uncertainty within the current TRMM products, but also serves as an opportunity to prototype error characterization methodologies for the TRMM follow-on program, the Global Precipitation Measurement (GPM) . Most of the TRMM uncertainty evaluation studies focus on the accuracy of rainfall accumulated over time (e.g., season/year). Evaluation of instantaneous rainfall intensities from TRMM orbital data products is relatively rare. These instantaneous products are known to potentially cause large uncertainties during real time flood forecasting studies at the watershed scale. This is more so over land regions, where the highly varying land surface emissivity offers a myriad of complications, hindering accurate rainfall estimation. The error components of orbital data products also tend to interact nonlinearly with hydrologic modeling uncertainty. Keeping these in mind, the present thesis fosters the development of uncertainty analysis using instantaneous satellite orbital data products (latest version 7 of 1B11, 2A25, 2A23, 2B31, 2A12) derived from the passive and active microwave sensors onboard TRMM satellite, namely TRMM Microwave Imager (TMI) and precipitation radar (PR). The study utilizes 11 years of orbital data from 2002 to 2012 over the Indian subcontinent and examines the influence of various error sources on the convective and stratiform precipitation types. Two approaches are taken up to examine uncertainty. While the first approach analyses independent contribution of error from these orbital data products, the second approach examines their combined effect. Based on the first approach, analysis conducted over the land regions of Mahanadi basin, India investigates three sources of uncertainty in detail. These include 1) errors due to improper delineation of rainfall signature within microwave footprint (rain/no rain classification), 2) uncertainty offered by the transfer function linking rainfall with TMI low frequency channels and 3) sampling errors owing to the narrow swath and infrequent visits of TRMM sensors. The second approach is hinged on evaluating the performance of rainfall estimates from each of these orbital data products by accumulating them within a spatial domain and using error decomposition methodologies. Microwave radiometers have taken unprecedented satellite images of earth’s weather, proving to be a valuable tool for quantitative estimation of precipitation from space. However, as mentioned earlier, with the widespread acceptance of microwave based precipitation products, it has also been recognized that they contain large uncertainties. One such source of uncertainty is contributed by improper detection of rainfall signature within radiometer footprints. To date, the most-advanced passive microwave retrieval algorithms make use of databases constructed by cloud or numerical weather model simulations that associate calculated microwave brightness temperature to physically plausible sample rain events. Delineation of rainfall signature from microwave footprints, also known as rain/norain classification (RNC) is an essential step without which the succeeding retrieval technique (using the database) gets corrupted easily. Although tremendous advances have been made to catapult RNC algorithms from simple empirical relations formulated for computational expedience to elaborate computer intensive schemes which effectively discriminate rainfall, a number of challenges remain to be addressed. Most of the algorithms that are globally developed for land, ocean and coastal regions may not perform well for regional catchments of small areal extent. Motivated by this fact, the present work develops a regional rainfall detection algorithm based on scattering index methodology for the land regions of study area. Performance evaluation of this algorithm, developed using low frequency channels (of 19 GHz, 22 GHz), are statistically tested for individual case study events during 2011 and 2012 Indian summer monsoonal months. Contingency table statistics and performance diagram show superior performance of the algorithm for land regions of the study region with accurate rain detection observed in 95% of the case studies. However, an important limitation of this approach is comparatively poor detection of low intensity stratiform rainfall. The second source of uncertainty which is addressed by the present thesis, involves prediction of overland rainfall using TMI low frequency channels. Land, being a radiometrically warm and highly variable background, offers a myriad of complications for overland rain retrieval using microwave radiometer (like TMI). Hence, land rainfall algorithms of TRMM TMI have traditionally incorporated empirical relations of microwave brightness temperature (Tb) with rain rate, rather than relying on physically based radiative transfer modeling of rainfall (as implemented in TMI ocean algorithm). In the present study, sensitivity analysis is conducted using spearman rank correlation coefficient as the indicator, to estimate the best combination of TMI low frequency channels that are highly sensitive to near surface rainfall rate (NSR) from PR. Results indicate that, the TMI channel combinations not only contain information about rainfall wherein liquid water drops are the dominant hydrometeors, but also aids in surface noise reduction over a predominantly vegetative land surface background. Further, the variations of rainfall signature in these channel combinations were seldom assessed properly due to their inherent uncertainties and highly non linear relationship with rainfall. Copula theory is a powerful tool to characterize dependency between complex hydrological variables as well as aid in uncertainty modeling by ensemble generation. Hence, this work proposes a regional model using Archimedean copulas, to study dependency of TMI channel combinations with respect to precipitation, over the land regions of Mahanadi basin, India, using version 7 orbital data from TMI and PR. Studies conducted for different rainfall regimes over the study area show suitability of Clayton and Gumbel copula for modeling convective and stratiform rainfall types for majority of the intraseasonal months. Further, large ensembles of TMI Tb (from the highly sensitive TMI channel combination) were generated conditional on various quantiles (25th, 50th, 75th, 95th) of both convective and stratiform rainfall types. Comparatively greater ambiguity was observed in modeling extreme values of convective rain type. Finally, the efficiency of the proposed model was tested by comparing the results with traditionally employed linear and quadratic models. Results reveal superior performance of the proposed copula based technique. Another persistent source of uncertainty inherent in low earth orbiting satellites like TRMM arise due to sampling errors of non negligible proportions owing to the narrow swath of satellite sensors coupled with a lack of continuous coverage due to infrequent satellite visits. This study investigates sampling uncertainty of seasonal rainfall estimates from PR, based on 11 years of PR 2A25 data product over the Indian subcontinent. A statistical bootstrap technique is employed to estimate the relative sampling errors using the PR data themselves. Results verify power law scaling characteristics of relative sampling errors with respect to space time scale of measurement. Sampling uncertainty estimates for mean seasonal rainfall was found to exhibit seasonal variations. To give a practical demonstration of the implications of bootstrap technique, PR relative sampling errors over the sub tropical river basin of Mahanadi, India were examined. Results revealed that bootstrap technique incurred relative sampling errors of <30% (for 20 grid), <35% (for 10 grid), <40% (for 0.50 grid) and <50% (for 0.250 grid). With respect to rainfall type, overall sampling uncertainty was found to be dominated by sampling uncertainty due to stratiform rainfall over the basin. In order to study the effect of sampling type on relative sampling uncertainty, the study compares the resulting error estimates with those obtained from latin hypercube sampling. Based on this study, it may be concluded that bootstrap approach can be successfully used for ascertaining relative sampling errors offered by TRMM-like satellites over gauged or ungauged basins lacking in in-situ validation data. One of the important goals of TRMM Ground Validation Program has been to estimate the random and systematic uncertainty associated with TRMM rainfall estimates. Disentangling uncertainty in seasonal rainfall offered by independent observations of TMI and PR enables to identify errors and inconsistencies in the measurements by these instruments. Motivated by this thought, the present work examines the spatial error structure of daily precipitation derived from the version 7 TRMM instantaneous orbital data products through comparison with the APHRODITE data over a subtropical region namely Mahanadi river basin of the Indian subcontinent for the seasonal rainfall of 6 years from June 2002 to September 2007. The instantaneous products examined include TMI and PR data products of 2A12, 2A25 and 2B31 (combined data from PR and TMI). The spatial distribution of uncertainty from these data products was quantified based on the performance metrics derived from the contingency table. For the seasonal daily precipitation over 10x10 grids, the data product of 2A12 showed greater skill in detecting and quantifying the volume of rainfall when compared with 2A25 and 2B31 data products. Error characterization using various error models revealed that random errors from multiplicative error models were homoscedastic and that they better represented rainfall estimates from 2A12 algorithm. Error decomposition technique, performed to disentangle systematic and random errors, testified that the multiplicative error model representing rainfall from 2A12 algorithm, successfully estimated a greater percentage of systematic error than 2A25 or 2B31 algorithms. Results indicate that even though the radiometer derived 2A12 is known to suffer from many sources of uncertainties, spatial and temporal analysis over the case study region testifies that the 2A12 rainfall estimates are in a very good agreement with the reference estimates for the data period considered. These findings clearly document that proper characterization of error structure offered by TMI and PR has wider implications in decision making, prior to incorporating the resulting orbital products for basin scale hydrologic modeling. The current missions of GPM envision a constellation of microwave sensors that can provide instantaneous products with a relatively negligible sampling error at daily or higher time scales. This study due to its simplicity and physical approach offers the ideal basis for future improvements in uncertainty modeling in precipitation.