A exposição ambiental ao chumbo é uma das questões mais sérias de contaminação de populações do ponto de vista de saúde pública. Mesmo em pequenas quantidades, o chumbo causa mudanças bioquímicas e neurológicas, convulsões e hiperatividade. No Brasil, não existe programa nacional para detecção de crianças contaminadas por este metal, as quais são mais sensíveis aos efeitos deletérios resultantes da exposição crônica a baixas concentrações de chumbo. A maioria dos trabalhos que comprovaram a associação entre exposição ambiental a chumbo no passado e problemas no desenvolvimento neurológico utilizou dentina de dentes decíduos como tecido marcador de exposição. Trabalhos do nosso grupo indicam que o esmalte superficial de dentes decíduos seria um bom marcador cumulativo da exposição passada ao chumbo, sendo que esse tecido apresenta consideráveis vantagens do ponto de vista de acesso e desenvolvimento de testes para monitoramento ambiental. Uma questão importante é verificar se as concentrações de chumbo encontradas no esmalte superficial decíduo variam ao longo do tempo em crianças de baixa exposição. Outra questão importante é verificar se há correlações entre as concentrações de chumbo no esmalte superficial e aquelas dos principais fluidos corporais a partir dos quais o chumbo seria acumulado no esmalte, que são sangue total, plasma e saliva. Assim, o objetivo deste trabalho foi verificar in vivo, por meio de testes em esmalte em dentes decíduos, se o chumbo acumulado nos primeiros micrometros do esmalte aumenta ao longo de três anos e se as concentrações de chumbo encontradas no esmalte apresentam correlação com aquelas encontradas no sangue total, plasma e saliva. A amostra inicial foi constituída por 50 crianças com idade de 2 a 3 anos procedentes de Ribeirão Preto que estavam recebendo atendimento odontológico na Clínica Infantil da Faculdade de Odontologia de Ribeirão Preto USP e alunos da Creche Carochinha (USPRibeirão Preto). Obtiveram-se as seguintes amostras: primeira etapa (2009): 01 amostra de sangue total e 01 amostra de esmalte de um incisivo central superior; segunda etapa (2010): 01 amostra de sangue total, 01 amostra de plasma sanguíneo, 01 amostra de saliva e 01 amostra de esmalte do dente contralateral. terceira etapa (2011): 01 amostra de sangue total, 01 amostra de plasma sanguíneo, 01 amostra de saliva e 02 amostras de amostra de esmalte dos incisivos laterais. O fósforo foi determinado colorimetricamente, para calcular a profundidade dos testes de esmalte. As concentrações de chumbo no plasma, saliva e esmalte dental foram determinadas por espectrometria de massas com plasma indutivamente acoplado (ICPMS) e no sangue total, por espectrometria de absorção atômica com forno de grafite. Muitas crianças ou seus responsáveis não permitiram a coleta de sangue em algum dos períodos, e assim ao longo dos 3 anos tivemos participação efetiva de 20 crianças. Em 2009, a concentração de chumbo no sangue total variou de 0,2 μg/dL a 7,48 μg/dL e teve como a mediana 0,26 μg/dL. Apenas uma criança apresentou nível de chumbo no sangue 5 μg/dL. Em 2010, a concentração de chumbo no sangue total variou de 0.2 μg/dL a 3,8 μg/dL e teve como a mediana 0,32 μg/dL. Em 2011, a concentração de chumbo no sangue variou de 1,15 μg/dL a 3,55 μg/dL e teve como mediana 0,95 μg/dL. Os dados de chumbo no sangue não apresentam diferenças estatisticamente significantes entre os grupos ao longo dos anos (p>0.05). Em 2010, valores de chumbo no plasma variaram de 0,29 3,20 μg/L e a mediana foi 0,49. Em 2011, variaram de 0,38 1,60 μg/L com mediana 0,52 μg/L. A concentração de chumbo na saliva em 2010 variou de 0,02 3,00 μg/L, com mediana de 0,34 μg/L. Em 2011, esses valores variaram de 0,02 4,27 μg/L e a mediana foi de 0,19 μg/L. Para as concentrações de chumbo no plasma e na saliva, não houve diferenças estatisticamente significantes entre os grupos (Saliva 2010 x Saliva 2011; Plasma 2010 x Plasma 2011) (teste de Mann Whitney; p>0.05). No caso dos dados obtidos no esmalte dentário, os valores de chumbo foram recalculados para uma mesma profundidade, que foi de 3,4 μm. Nenhum dos grupos (Esmalte 2009, Esmalte 2010 e Esmalte 2011) teve distribuição normal, e não houve diferença entre nas concentrações de chumbo encontradas ao longo dos anos, com medianas de 36, 35 e 38 μg/g em 2009, 2010 e 2011, respectivamente (p=0,71, teste de Kruskal-Wallis). A análise de correlação foi feita após a transformação logarítmica (log10) de todos os valores. Mesmo após esta transformação, dois grupos ainda não apresentaram distribuição normal, o grupo Plasma 2011 e Esmalte 2010. As associações que envolviam estes grupos foram testadas utilizando-se a correlação de Spearman, enquanto todas as demais associações foram testadas utilizando-se o teste de correlação de Pearson. As correlações significativas positivas encontradas foram: entre Sangue Total 2009 e Sangue Total 2010 (rP = 0,64; p = 0,002) ; Sangue Total 2010 e Sangue Total 2011 (rP = 0,66; p = 0,002); Esmalte 2011 e Sangue Total 2009 (rP= 0,44; p=0,05) e entre Esmalte 2009 e Esmalte 2010 (rS = 0,45 e p=0,03). Houve uma associação inversa entre a Saliva 2010 e Esmalte 2011 (rP = - 0,55; p=0,013). Conclusão: Os valores de chumbo obtidos em todas as amostras ao longo de 3 anos caracterizam baixa exposição a chumbo no grupo estudado. As concentrações de chumbo no sangue, saliva, plasma e esmalte não variaram ao longo do tempo. Das 28 associações testadas, foram estatisticamente significantes e positivas aquelas entre o Sangue Total 2009 e o Esmalte 2011 e entre o Esmalte 2009 e Esmalte 2010. A associação entre Saliva 2010 e Esmalte 2011 foi inversa. Os resultados sugerem que o esmalte tenha associação com a exposição de chumbo passada, neste estudo caracterizado pelos valores de chumbo no sangue total. Os resultados sugerem que o esmalte possa ser um biomarcador fidedigno para avaliar o grau de exposição a chumbo em populações com baixa exposição a este metal, uma vez que o esmalte superficial de dentes decíduos não incorporou chumbo em quantidades significativas entre 2 e 5 anos de idade em crianças com baixa exposição e baixa atividade de cárie. / Environmental exposure to lead is one of the most serious contamination problems that affect public health. Even in small amounts, lead can cause neurological and biochemical changes, such as mental problems and hyperactivity. In Brazil, there is no program for the detection of children contaminated by this metal. Children are more sensitive to the deleterious effects of chronic lead exposure. Studies that proved association between environmental exposure to lead and neurological developmental problems used dentine of primary teeth as a marker of lead exposure. Studies by our group suggest that superficial enamel of deciduous teeth would be a good cumulative marker of past exposure to lead, and this tissue has considerable advantages regarding access and the perspective of development of tests for environmental monitoring of children. An important question is whether the concentrations of lead found in deciduous enamel surface vary over time in children with low exposure and if there are correlations between the concentrations of lead in the enamel surface and those of the main body fluids from which the lead was accumulated in the enamel, which are whole blood, plasma and saliva. The aims of this study was to investigate in vivo, by testing lead concentration in deciduous enamel of primary teeth, if the lead accumulated in the first micrometers of enamel increases along three years and if the concentrations of lead found in enamel surface were correlated with those found in whole blood, plasma and saliva. The initial sample consisted of 50 children aged 2 to 3 years from Ribeirão Preto, who were receiving dental care at Children\'s Clinic of the Faculty of Dentistry of Ribeirão Preto - USP and students of Nursery Carochinha (USP-Ribeirão Preto). The following samples were obtained: first stage (2009): 01 sample of whole blood and 01 sample of enamel of a central upper incisor, second stage (2010): 01 sample of whole blood, 01 sample of blood plasma, 01 sample of saliva and 01 sample of enamel from the contralateral tooth; third stage (2011): 01 sample of whole blood, 01 sample of blood plasma, 01 sample of saliva and 02 enamel samples of lateral upper incisors. Phosphorus was determined by a colorimetric method, in order to calculate the depth of enamel tests. Lead concentrations in plasma, saliva and enamel were determined by inductively coupled plasma mass spectrometry (ICPMS) and whole blood by atomic absorption spectrometer with graphite furnace. Many children or their guardians did not allow the collection of blood in any of the periods, and thus, over the three years, we had the enrollment of only 20 children. In 2009, the concentration of lead in whole blood varied from 0.2 μg / dL to 7.48 μg /dL and the median was 0.26 μg/dL. Only one child had a blood lead level 5 μg/ dL. In 2010, the concentration of lead in whole blood ranged from 0.2 μg/dL to 3.8 μg/dL and the median was 0.32 μg/dL. In 2011, the concentration of lead in blood ranged from 1.15 μg/dL to 3.55 μg/dL and the median was 0.95 μg/dL. The blood lead data do not show statistically significant differences over the years (p> 0.05). In 2010, values of lead in plasma ranged from 0.29 to 3.20 μg/L and the median was 0.49 μg/L. In 2011, lead levels in plasma ranged from 0.38 to 1.60 μg/L with median 0.52 μg/L. The lead concentration in Saliva 2010 ranged from 0.02 to 3.00μ g/L, median 0.34 μg/L. In 2011, these values ranged from 0.02 to 4.27 μg/L and the median was 0.19 μg/L. For lead concentrations in plasma and saliva, there were no statistically significant differences between groups (Saliva 2010 x Saliva 2011; Plasma 2010 x Plasma 2011)(Mann-Whitney test, p> 0.05). To analyze enamel samples, the values of lead were recalculated so they would reflect the lead found in one same depth, which was 3.4 micrometers. None of the groups (enamel from 2009, enamel from 2010 and enamel from 2011) presented normal distribution. There was no statistically significant difference between these three groups (p=0.71, Kruskal-Wallis). A correlation analysis was performed after logarithmic transformation (log10) of all values. Even after this transformation, two groups still did not exhibit normal distribution, which were Plasma 2011 & Enamel 2010. The associations that involved these two groups were tested using the Spearman correlation test, while all other associations were tested using the Pearson correlation test. The significant positive correlations found were: Whole Blood 2009 and Whole Blood 2010 (rP = 0,64; p = 0,002) ; Whole Blood 2010 and Whole Blood 2011 (rP = 0,66; p = 0,002); between Enamel 2011 and Whole Blood 2009 (rP= 0.44, p = 0.05) and between Enamel 2009 and Enamel 2010 (rS= 0.45, p= 0.03). There was an inverse association between Saliva 2010 and Enamel 2011 (rP= - 0,55; p = 0,013). Conclusion: The lead values obtained in all samples over three years characterized low exposure to lead by the group studied. Lead concentrations in blood, saliva, plasma and enamel did not vary over time. Of the 28 associations tested, the ones between Whole Blood 2009 and 2011 and between Enamel 2009 and 2010 were positive and significant. The association between Saliva 2010 and Enamel 2011 was negative and significant. The results suggest that the lead found in the enamel is correlated with past exposure to lead characterized in this study by the yearly whole blood lead data. The results further suggest that the dental enamel can be a reliable marker to assess the degree of exposure to lead of populations, since the primary teeth´s enamel surface did not incorporate lead in substantial quantities between 2 and 5 years in children with low exposure to this metal and low caries activity.

abstract: Social media has become the norm of everyone for communication. The usage of social media has increased exponentially in the last decade. The myriads of Social media services such as Facebook, Twitter, Snapchat, and Instagram etc allow people to connect with their friends, and followers freely. The attackers who try to take advantage of this situation has also increased at an exponential rate. Every social media service has its own recommender systems and user profiling algorithms. These algorithms use users current information to make different recommendations. Often the data that is formed from social media services is Linked data as each item/user is usually linked with other users/items. Recommender systems due to their ubiquitous and prominent nature are prone to several forms of attacks. One of the major form of attacks is poisoning the training set data. As recommender systems use current user/item information as the training set to make recommendations, the attacker tries to modify the training set in such a way that the recommender system would benefit the attacker or give incorrect recommendations and hence failing in its basic functionality. Most existing training set attack algorithms work with ``flat" attribute-value data which is typically assumed to be independent and identically distributed (i.i.d.). However, the i.i.d. assumption does not hold for social media data since it is inherently linked as described above. Usage of user-similarity with Graph Regularizer in morphing the training data produces best results to attacker. This thesis proves the same by demonstrating with experiments on Collaborative Filtering with multiple datasets. / Dissertation/Thesis / Masters Thesis Computer Science 2019

This research integrates the theoretical implications of risk perception, the social amplification of risk, and the role of place-specific contexts, in order to explore the various perceptions surrounding Florida red tides. Florida red tides are a naturally-occurring event, yet most scientists agree that they are increasing in frequency, duration, and severity. This has profound implication for public health, the local economy, and the biological community. While many of the negative impacts are not easily controllable at this time, some of the secondary impacts can be mitigated through individuals' responses. Unfortunately, public perceptions and consequent reactions to red tides have not been investigated. This research uses questionnaire surveys, semi-structured interviews, and newspaper content analysis to explore the various perceptions of risk surrounding red tides. Surveys and interviews were conducted along two Florida west coast beaches, Fort De Soto Park and Siesta Key. Results indicate that the underlying foundations of the social amplification of risk framework are applicable to understanding how individuals form perceptions of risk relative to red tide events. There are key differences between the spatial locations of individuals and corresponding perceptions, indicating that place-specific contexts are essential to understanding how individuals receive and interpret risk information. The results also suggest that individuals may be lacking efficient and up-to-date information about red tides and their impacts due to inconsistent public outreach. Overall, particular social and spatial factors appear to be more influential as to whether individuals amplify or attenuate the risks associated with red tides.

The United States is in the midst of an opioid epidemic. In addition to other system level interventions, almost all states have responded to the crisis by implementing prescription drug monitoring programs (PDMPs). PDMPs are state-level interventions that track the dispensing of Controlled Substances. Data generated at the time of medication dispensing is uploaded to a central data server that may be used to assist in identifying drug diversion, medication misuse, or potentially aberrant prescribing practices. Prior studies assessing the impact of PDMPs on trends in opioid-related morbidity have often failed to take into account the wide heterogeneity of program features and how the effectiveness of these features may be mitigated by insurance status. Previous research has also failed to differentiate the effects of these programs on prescription vs. illicit opioid-related morbidity. The studies in this dissertation attempt to address these gaps using epidemiological techniques to examine the associations between specific PDMP features and trends in prescription and illicit opioid-related poisonings in populations of different insurance beneficiaries. Results of these studies demonstrate that implementation of specific PDMP features is significantly associated with differential trends in prescription and illicit-opioid related poisonings and that the effectiveness of these features vary depending on the insurance status of the population studied. These results suggest that PDMPs offer a valuable tool in addressing the United States’ opioid epidemic, and may be used as empirical evidence to support PDMP best practices in the future.

<p>This study reports on the changes in the structural properties of a tungsten-filament when exposed to a methane / hydrogen ambient for different durations at various filament-temperatures.</p>

This study is aimed to assess the extent of street food vendor information and education on food safety. Aim: To determine the knowledge, attitudes and practices (KAP) of street food vendors, within the City of Johannesburg, with regard to food hygiene and safety. Methods: A descriptive, cross-sectional study utilizing a quantitative research approach. Data was collected through face-to-face interviewing of street food vendors, with observations of general hygiene and cleanliness. Data was captured in Excel and imported into CDC Epi Info version 3.4.3 (2007) for analysis. Numerical data was analyzed using descriptive statistics and categorical data was analyzed using frequencies. Bivariate analysis was used to establish differences between regions with high and low proportions of street food vendors with regard to knowledge, practices and attitudes variables.

High fossil fuel consumption in transportation and industry results in an increase of the emission of green-house gases. To preserve clean air, new strategies are required. The main intention is to decrease the amount of CO2 emission by using lean-burn engines while increasing the combustion efficiency and decreasing the fuel consumption. However, the lean-burn engines have high air-to-fuel ratio which complicates the reduction of the oxides of nitrogen, NOx . The emission of these highly noxious pollutants, NOx , breeds both environmental and health problems. Thus, new catalytic strategies have been steadily developed. One of these strategies is the NOx storage and reduction (NSR) catalysts. Since the reduction of the NOx under excess oxygen condition is very difficult, the NSR catalysts store the NOx until the end of the lean phase that is subsequently alternated with the rich-fuel phase during which the trapped NOx is released and reduced. To develop NSR technology, different storage materials, the coverage of these metals/metal-oxides, support materials, precious metals, temperature, etc. have been widely investigated. In this thesis, the (100) surface of BaO with dopants (K, Na, Ca and La), (100) and (110) surfaces of Li2O, Na2O and K2O are investigated as storage materials. In addition, alkali metal (Li, Na and K) loaded (001) surface of TiO2 (titania) anatase is investigated as a support material for the NOx storage and reduction catalysts. The main aim is to increase the sulfur resistance. The introduction of the dopants on the BaO (100) surface has increased the stability of the NO2 . The combination of local lattice strain and different oxidation state, which is obtained by the La doped BaO (100) surface, benefit both NO2 adsorption performance and sulfur tolerance. The binding energies of NO2 adsorption configurations over the alkali metal oxide (100) and (110) surfaces were higher than the binding energies of SO2 adsorption configurations. The stability of all of NO2 adsorption geometries on the alkali metal-loaded TiO2 (001) surface were higher than the stability of SO2 adsorption geometries. Increasing basicity enhanced the adsorption of NO2 molecule.

Unlike polymer electrolyte fuel cells, solid-oxide fuel cells (SOFCs) have the potential to use a wide variety of fuels, including hydrocarbons and gasified coal or different types of ample carbonaceous solids. However, the conventional anode for an SOFC, a composite consisting of nickel and yttria-stabilized-zirconia (YSZ), is highly susceptible to carbon buildup (coking) and deactivation (poisoning) by contaminants commonly encountered in readily available fuels. Further, the low ionic conductivity of the electrolyte and the poor performance of the cathode at lower temperatures require SOFCs to operate at high temperatures (>800°C), thereby increasing costs and reduce system operation life. Thus, in order to make SOFCs fully fuel-flexible, cost-effective power systems, the issues of anode tolerance to coking and sulfur poisoning as well as the slow ionic conduction in the electrolyte and the sluggish kinetics at the cathode need to be addressed. In this thesis, a novel electrolyte was shown to have the highest ionic conductivity below 750°C of all known electrolyte materials for SOFCs applications, which allowed for fabrication of a thin-electrolyte cell with high power output at lower temperatures. The detailed electrochemical analyses of BZCYYb conductor revealed that the conductivities were sensitive to doping and partial pressure of oxygen, hydrogen, and water. When used in combination with Ni as a composite anode (Ni-BZCYYb), it was shown to provide excellent tolerance to coking and sulfur poisoning. Extensive investigations on surfaces of BZCYYb and Ni by Raman Spectroscopy and Scanning Auger Nanoprobe disclosed that its unique ability appears linked to the mixed conductor's enhanced catalytic activity for sulfur oxidation and hydrocarbon cracking/reforming, as well as enhanced multilayer water adsorption capability. In addition, the nanostructured oxide layers on Ni from dispersion of BZCYYb traces during high-temperature calcinations may effectively suppress the formation of carbon from dehydrogenation. Based on the fundamental understanding on surface properties, a new and simple modification strategy was developed to hinder the carbon-induced deactivation of the state-of-the-art Ni-YSZ anode. Compared to the complex Ni-BZCYYb anode, this modified Ni-YSZ anode could be readily adopted in the latest fuel cell systems based on YSZ electrolyte. The much-improved power output and tolerance to coking of the modified Ni-YSZ anode were attributed to the nanostructured BaO/Ni interfaces observed by synchrotron-based X-ray and advanced electron microscopy, which readily adsorbed water and facilitated water-mediated carbon removal reactions. Density functional theory (DFT) calculations predicted that the dissociated OH from H₂O on BaO reacted with C on Ni near the BaO/Ni interface to produce CO and H species, which were then electrochemically oxidized at the triple-phase boundaries of the anode. Also, some new insights into the sulfur poisoning behavior of the Ni-YSZ anode have been revealed. The so-called "second-stage poisoning" commonly reported in the literatures can be avoided by using a new sealant, indicating that this poisoning is unlikely the inherent electrochemical behavior of a Ni-YSZ anode but associated with other complications. Furthermore, a new composite cathode with simultaneous transport of proton, oxygen vacancies and electronic defects was developed for low-temperature SOFCs based on oxide proton conductors. Compared to the conventional oxygen ion-electron conducting cathode, this cathode is very active for oxygen reduction, extending the electrochemically active sites and significantly reducing the cathodic polarization resistance. Towards the end, these findings have great potential to dramatically improve the economical competitiveness and commercial viability of SOFCs that are driven by cost-effective and renewable fuels.

Domoic acid (DA), a potent neurotoxin that has the potential to cause amnesic shellfish poisoning (ASP), is produced by members of the marine diatom genus Pseudo-nitzschia. Outbreaks of ASP in humans and of DA poisoning in birds and marine mammals have been reported across the United States and Canada since the late 1980's. Pseudo-nitzschia species can be extremely abundant in Florida waters, with densities often exceeding 106 cells/L, and sometimes exceeding 107 cells/L. Based on preliminary data, it is evident that at least nine species of Pseudo-nitzschia are found in Florida coastal waters. At least six of these species are known to produce DA in other parts of the world, and some are morphologically identical to some of the major toxin-producing species in Californian and Canadian waters. Despite the strong presence of Pseudo-nitzschia, there has never been a report of ASP or a DA-related animal mortality event from Florida. Data collected from 2004 to 2011 show maximum Pseudo-nitzschia abundances exceeded 4 x 107 cells/L. Six species of Pseudo-nitzschia were identified from central west and southwest Florida waters via light and electron microscopy. This is the first report of P. micropora from the Gulf of Mexico. Additionally P. calliantha, P. cuspidata, and P. pungens were identified as producers of DA in Florida coastal waters; although cell quotas of DA were low. Low levels of DA were detected in about one third of the water samples analyzed and DA concentrations measured in the majority of shellfish from the study area were at least an order of magnitude below the regulatory limit of 20 µg/g, suggesting that Pseudo-nitzschia currently poses little threat to human health in Florida. However, DA production in Pseudo-nitzschia species has been shown to be variable and dependent on nutrient conditions, indicating that the potential for DA-related events to occur in Florida warrants further investigation.

<p>This study reports on the changes in the structural properties of a tungsten-filament when exposed to a methane / hydrogen ambient for different durations at various filament-temperatures.</p>