The study presents a numerical analysis of series of unanticipated events that took place upon the excavation of a landfill in a deep deposit of clayey soil in southwestern Ontario, Canada. During the excavation of a landfill cell to be used for waste disposal, unexpected lateral slope movements were observed followed by gas and water venting in several locations (while the excavation in low permeability clayey till was about 14m above the underlying aquifer). The clayey till is known to be underlain by permeable, natural gas bearing rock, and gas has been diffusing through the clayey deposit over about the last 13,000-15,000 years. Preliminary 2D and 3D elasto-plastic effective stress analyses using conventional soil mechanics –similar to what was used in design- are used to capture the general behaviour of the excavation. However, the analyses revealed the need for model modification to account for other governing factors (gassy soil and hydrofracturing) to be able to explain the mechanism that might have lead to the evolution of gas vents and upward water flow through the thick shale aquitard. The clayey deposit contains silty sand lenses at different elevations. The upward diffusion of methane and chloride from the bedrock aquifer through the clay till is modelled and the potential for chloride migration contributing to the exsolution of methane due to reduction in methane solubility is discussed. Two approaches to modelling the lenses are examined where gas exsolution either occurs prior to or during the excavation. The FE model is modified to account for hydrofacturing and gassy soil behaviour (for sand lenses). 2D and 3D forensic modelling studies are presented examining the potential causes for the unanticipated movements and the gas and water venting observed during the excavation. The model investigates the role of presence of gassy sand lenses and of the presence of a discontinuous weak sandy clayey silt layer between the bedrock and the low permeability till on the hydrofracturing path and gas venting. Finally, a parametric study is conducted to examine the effect of different parameters on the soil behaviour when excavated. Recommendations regarding further excavations within the same soil deposit are presented. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2012-08-23 16:33:05.062

Cotton is the most abundant natural fiber in the world. Many countries are involved in the growing, importation, exportation and production of this commodity. Paper documentation claiming geographic origin is the current method employed at U.S. ports for identifying cotton sources and enforcing tariffs. Because customs documentation can be easily falsified, it is necessary to develop a robust method for authenticating or refuting the source of the cotton commodities. This work presents, for the first time, a comprehensive approach to the chemical characterization of unprocessed cotton in order to provide an independent tool to establish geographic origin. Elemental and stable isotope ratio analysis of unprocessed cotton provides a means to increase the ability to distinguish cotton in addition to any physical and morphological examinations that could be, and are currently performed. Elemental analysis has been conducted using LA-ICP-MS, LA-ICP-OES and LIBS in order to offer a direct comparison of the analytical performance of each technique and determine the utility of each technique for this purpose. Multivariate predictive modeling approaches are used to determine the potential of elemental and stable isotopic information to aide in the geographic provenancing of unprocessed cotton of both domestic and foreign origin. These approaches assess the stability of the profiles to temporal and spatial variation to determine the feasibility of this application. This dissertation also evaluates plasma conditions and ablation processes so as to improve the quality of analytical measurements made using atomic emission spectroscopy techniques. These interactions, in LIBS particularly, are assessed to determine any potential simplification of the instrumental design and method development phases. This is accomplished through the analysis of several matrices representing different physical substrates to determine the potential of adopting universal LIBS parameters for 532 nm and 1064 nm LIBS for some important operating parameters. A novel approach to evaluate both ablation processes and plasma conditions using a single measurement was developed and utilized to determine the “useful ablation efficiency” for different materials. The work presented here demonstrates the potential for an a priori prediction of some probable laser parameters important in analytical LIBS measurement.

Algae “super blooms” are a commonly encountered environmental issue in fresh and brackish water that occurs due to the buildup of cyanobacteria. Many of the commonly encountered cyanobacteria such as Mycrocystis aeruginosa (M. aeruginosa) produce potent cyanotoxins (microcystins) that pose serious health threats and even death to local wild life and humans. Microcystin contaminated fresh-water that empties into the ocean has been shown to lethally affect marine life in the area of contamination. Human consumption of tainted sea life and other routes of mycrocystin exposure can lead to serious liver damage and even death. Thus, a method was developed for forensic postmortem analysis of microcystins RR, LR and YR by Two-Dimensional (2D) Liquid Chromatography (LC) - tandem Mass Spectrometry (MS/MS). A final 2D LC-MS/MS method was selected from 6x6 automated method development experiments. Each microcystin were subjected to a total of 36 methods, which were completed over an 18hr period. The extraction process was performed using a reverse-phase sorbent (Oasis HLB, Waters Corporation, Milford, MA) with a 3cc solid phase extraction (SPE) barrel using sequential elution. From acetonitrile (ACN) and methanol (MeOH) stock solutions, 10 μL of the internal standard (IS) Nodularin was added to the final extract. The concept of sequential micro extraction was designed to capture the retention behaviour of the target analyte in response to various extraction parameters (sorbent strength, elution polarity, and solubility). Therefore, optimized conditions were selected to excise the region of interest during extraction. The elution solvents chosen for the microcystins were acetonitrile, methanol and acetone with 10 % sequential increments. Since microcystins exhibit a zwitterionic structure, three sets of elution solutions were created to evaluate their elution profile (pH 3, pH 7, pH 10). When the elution profile for low pH and high pH are compared, microcystin RR was eluted over the 40% to 70% methanol fractions under low pH conditions with a slight shift towards higher organic % (50%-70% fractions) under high pH. This elution behaviour suggests that the basic moieties of the structure demonstrate a stronger retention for the stationary phase. Microcystin LR and YR however, eluted at a higher organic solvent percentage under low pH conditions and at a lower organic solvent percentage under high pH conditions, indicates that the acidic moieties of the structures have stronger retention. The urine sample gave recovery values for all three microcystins in the 80-90% range, as to be expected with type of complexity associated with biological samples. The sequential extraction protocol produced an extraction method that delivered a clean extract after a 30 min workflow using a single and optimized 2D LC-MS/MS method. The total analytical run time was set at 10 minutes.

<p>WeChat is one of the most popular applications in the world. By 2021, there were 1.24 billion users of WeChat. Many people call it the `super app` because it is an application for everything. Besides the basic messaging feature, it also supports online payment, video posts, news feeds, and more. Due to its wide usage, many criminals are using the platforms for illegal activities such as bank fraud, cyberbullying, and stalking. For these reasons, we need to understand WeChat forensically to assist investigators in cases involving WeChat.</p> <p>Previous research was mostly focused on the messaging of the WeChat application. However, artifacts of other features remain on the device undiscovered. These features can provide crucial evidence to a case such as geo-locations or monetary transactions. WeChat keeps updates monthly, and these updates may add new features or modify the data structure. The official website does not provide a detailed description of its features so it is hard for a non-WeChat user to understand the functionalities. Therefore, research is required to analyze the background, structure, and possible artifacts remaining of the WeChat app to assist practitioners who encounter WeChat in an investigation. This study included all platforms that WeChat provides, Windows, MacOS, Android, and iOS.</p>

No description available.

Regulations and societal expectations have recently emphasized the need to mediate access to valuable databases, even by insiders. At one end of a spectrum is the approach of restricting access to information; at the other is information accountability. The focus of this work is on effecting information accountability of data stored in relational databases. One way to ensure appropriate use and thus end-to-end accountability of such information is through continuous assurance technology, via tamper detection in databases built upon cryptographic hashing. We show how to achieve information accountability by developing and refining the necessary approaches and ideas to support accountability in high-performance databases. These concepts include the design of a reference architecture for information accountability and several of its variants, the development of a sequence of successively more sophisticated forensic analysis algorithms and their forensic cost model, and a systematic formulation of forensic analysis for determining when the tampering occurred and what data were tampered with. We derive a lower bound for the forensic cost and prove that some of the algorithms are optimal under certain circumstances. We introduce a comprehensive taxonomy of the types of possible corruption events, along with an associated forensic analysis protocol that consolidates all extant forensic algorithms and the corresponding type(s) of corruption events they detect. Finally, we show how our information accountability solution can be used for databases residing in the cloud. In order to evaluate our ideas we design and implement an integrated tamper detection and forensic analysis system named DRAGOON. This work shows that information accountability is a viable alternative to information restriction for ensuring the correct storage, use, and maintenance of high-performance relational databases.

A adição de diferentes substâncias (adulterantes e diluentes) no crack (freebase) é um fenômeno bem conhecido no mercado ilícito. Os adulterantes podem interagir com a cocaína e determinar novas e desconhecidas síndromes tóxicas influindo no estado clínico das intoxicações, especialmente em casos em que houve modificação das vias de administração. No Brasil a análise de adulterantes, contaminantes e/ou diluentes adicionados ao crack não constitui rotina nos laboratórios oficiais. Nesse contexto, o presente trabalho pretendeu a caracterização de um grupo de amostras de crack que fornecerá informações na investigação sobre o narcotráfico, no estudo da morbi-letalidade, bem como na toxicovigilância. O método utilizado neste trabalho foi realizado com a técnica de cromatografia gasosa acoplada a detector em ionização de chamas CG-DIC. Os resultados obtidos nas análises de amostras provenientes de apreensões realizadas na região metropolitana de São Paulo num período de 20 meses, no período de março de 2008 a novembro de 2009, mostraram que 9,16% das amostras continham lidocaína, benzocaína e cafeína como adulterantes e 14,57% continham outros adulterantes totalizando 23,73%. O percentual em teor médio de cocaína presentes nas amostras de crack foi de 71,3%. Adicionalmente foram avaliadas as propriedades organolépticas. O resultado das análises das amostras estudadas mostrou maior teor de cocaína em relação à cocaína comercializada na forma de sal (cloridrato ou sulfato) comercializado como \"droga de rua\" no Estado de São Paulo. Ainda, os interferentes e adulterantes encontrados nas amostras estudadas permitem a inferência do importante problema de saúde pública advindos do uso dessa droga. / The addition of different substances (contaminants and fillers) in the crack (freebase) is a well known phenomenon in the illicit market. The contaminants can interact with cocaine and identify new and unknown toxic syndromes influencing the clinical state of intoxication, especially in cases where there was a modification of the routes. In Brazil, the analysis of adulterants, contaminants and / or extenders added to the crack is not routine in official laboratories. In this context, this work aims to characterize a sample group of crack that provides information on an investigation into drug trafficking in the study of morbidity and mortality, as well as toxicological. The method used in this study utilized the technique of gas chromatography coupled with flame ionization detector GC-FID. The analysis results of samples from seizures made in the metropolitan region of Sao Paulo in a period of 20 months, from March 2008 to November 2009 showed that 9.16% of the samples contained lidocaine, benzocaine, and caffeine as adulterants and 14.57% contained other adulterants totaling 23.73%. The average content in percentage of cocaine present in the samples of crack was 71.3%. Additionally, we evaluated the organoleptic properties of the row samples. The results of analysis of the samples tested showed higher levels of cocaine in the cocaine sold in the form of salt (hydrochloride or sulfate) marketed as \"street drug\" in the State of São Paulo. Still, the interferences and adulterants found in the samples studied allow the inference of important public health problem arising from the use of this drug.

A adição de diferentes substâncias (adulterantes e diluentes) no crack (freebase) é um fenômeno bem conhecido no mercado ilícito. Os adulterantes podem interagir com a cocaína e determinar novas e desconhecidas síndromes tóxicas influindo no estado clínico das intoxicações, especialmente em casos em que houve modificação das vias de administração. No Brasil a análise de adulterantes, contaminantes e/ou diluentes adicionados ao crack não constitui rotina nos laboratórios oficiais. Nesse contexto, o presente trabalho pretendeu a caracterização de um grupo de amostras de crack que fornecerá informações na investigação sobre o narcotráfico, no estudo da morbi-letalidade, bem como na toxicovigilância. O método utilizado neste trabalho foi realizado com a técnica de cromatografia gasosa acoplada a detector em ionização de chamas CG-DIC. Os resultados obtidos nas análises de amostras provenientes de apreensões realizadas na região metropolitana de São Paulo num período de 20 meses, no período de março de 2008 a novembro de 2009, mostraram que 9,16% das amostras continham lidocaína, benzocaína e cafeína como adulterantes e 14,57% continham outros adulterantes totalizando 23,73%. O percentual em teor médio de cocaína presentes nas amostras de crack foi de 71,3%. Adicionalmente foram avaliadas as propriedades organolépticas. O resultado das análises das amostras estudadas mostrou maior teor de cocaína em relação à cocaína comercializada na forma de sal (cloridrato ou sulfato) comercializado como \"droga de rua\" no Estado de São Paulo. Ainda, os interferentes e adulterantes encontrados nas amostras estudadas permitem a inferência do importante problema de saúde pública advindos do uso dessa droga. / The addition of different substances (contaminants and fillers) in the crack (freebase) is a well known phenomenon in the illicit market. The contaminants can interact with cocaine and identify new and unknown toxic syndromes influencing the clinical state of intoxication, especially in cases where there was a modification of the routes. In Brazil, the analysis of adulterants, contaminants and / or extenders added to the crack is not routine in official laboratories. In this context, this work aims to characterize a sample group of crack that provides information on an investigation into drug trafficking in the study of morbidity and mortality, as well as toxicological. The method used in this study utilized the technique of gas chromatography coupled with flame ionization detector GC-FID. The analysis results of samples from seizures made in the metropolitan region of Sao Paulo in a period of 20 months, from March 2008 to November 2009 showed that 9.16% of the samples contained lidocaine, benzocaine, and caffeine as adulterants and 14.57% contained other adulterants totaling 23.73%. The average content in percentage of cocaine present in the samples of crack was 71.3%. Additionally, we evaluated the organoleptic properties of the row samples. The results of analysis of the samples tested showed higher levels of cocaine in the cocaine sold in the form of salt (hydrochloride or sulfate) marketed as \"street drug\" in the State of São Paulo. Still, the interferences and adulterants found in the samples studied allow the inference of important public health problem arising from the use of this drug.

USF completed a research study in 2005, which prioritized the replacement of 85 deteriorating composite precast deck panel bridges. This thesis re-evaluates the original recommendations in the wake of failures of two of these bridges in 2007. Since funding will not allow all identified bridges to be replaced, it was necessary to determine the most effective repair methods. To assess USF’s recommendations, a forensic study was undertaken in which the most current inspection and work program documents on the two failed bridges were reviewed and FDOT personnel interviewed. The best repair procedures were determined by reviewing repair plans, specifications, reports and site visits. The study found the two bridges that failed had been correctly prioritized by USF (No. 1 of 18 and No. 8 of 15). A new, accelerated repair method encompassing complete bay replacement was developed in a pilot project funded by the Florida Department of Transportation.

It is shown in the literature that the NAT devices have become a convenient way to hide the identity of malicious behaviors. In this thesis, the aim is to identify the presence of the NAT devices in the network traffic and (if possible) to predict the number of users behind those NAT devices. To this end, I utilize different approaches and evaluate the performance of these approaches under different network environments represented by the availability of different data fields. To achieve this, I propose a machine learning (ML) based approach to detect NAT devices. I evaluate my approach against different passive fingerprinting techniques representing the state-of-the-art in the literature and show that the performance of the proposed ML based approach is very promising even without using any payload (application layer) information.