Student Voice report

Student Voice report and recommendations

An investigation of synthetic body covering materials in soil burials for forensic application

University of Technology Sydney. Faculty of Science.During the forensic investigation of grave sites artefacts are often located and have the potential to provide valuable information about the victim or the perpetrator. Such artefacts may include body coverings used by the perpetrator to interfere with the crime scene. Polymer materials are now frequently encountered at crime scenes and given their use in bag and carpet manufacture, there was an increased likelihood that this class of materials will form part of a clandestine grave. Understanding the degradation of these materials in potential crime scene soils will provide insight into the age and nature of the burial. Previous forensic research on polymers at the crime scene has mostly focused on identifying polymer materials such as fibres and the studies that have investigated polymer degradation, examined the effect degradation had on identifying the polymer rather than the information the polymer can provide about the burial. This thesis provides a comprehensive examination of the degradation of five commonly encountered polymers with potential to be used as body coverings in a variety of soil t types. A comparison of the suitability of a range of analytical techniques to understand polymer degradation associated with burial has also been made in this thesis. The five polymers -polyethylene (PE), polypropylene (PP), poly vinyl chloride (PVC), polyethylene terephthalate (PET) and nylon- in the form of films and carpets were buried in a series of laboratory controlled environments that varied by soil type, moisture content, soil pH and temperature for a burial period of 24 months. Scanning electron microscopy and atomic force microscopy were utilised for the examination of changes to the morphology of polymer surface. Spectroscopic analyses, including infrared, Raman and ultraviolet-visible spectroscopies, were applied to monitor changes to the chemical structure of the polymers and their additives. Thermal analysis was also investigated as an approach to monitoring the subtle changes associated with the degradation processes. This study determined that certain soil environments enhanced the degradation of the polymers in soil, while other environments were shown to preserve the polymers. The degradation of these polymers often included the interaction of polymer additives with the soil environment. The factors that were shown to enhance polymer degradation included the availability of water and the ability of the soil environment to encourage microbial growth. In this thesis, a combination of morphological changes determined by scanning electron microscopy and the microstructural changes determined using infrared spectroscopy, and to a lesser extent, thermal changes monitored using thermogravimetric analysis, were determined to be the most powerful methods for monitoring degradation processes in the polymer systems investigated. This thesis provides new knowledge about the impact different soil variations have on the degradation of polymers that are more and more likely to be found at clandestine grave sites

Reduced tillage in organic cropping systems on the Canadian prairies

Organic producers on the Canadian prairies rely heavily on tillage for weed control and soil nutrient management. Intensive tillage degrades soil quality, and therefore efforts to reduce tillage in organic agriculture are increasing. Research has focused on replacing tillage for green manure termination with alternative low-disturbance methods. The roller-crimper terminates green manures by rolling over the crop and creating a mulch that is anchored to the ground. Rolled mulches can suppress weeds and conserve soil moisture, but surface-placed residues can delay N mineralization and result in subsequent yield loss. Three field studies were conducted in Saskatchewan, Alberta and Manitoba using the roller-crimper to determine the extent to which tillage can be reduced in organic systems without negatively impacting nutrient availability and yield. At two sites in Saskatchewan, the effects of termination timing (early flower, late flower, early pod) and termination method (rolling, mowing, tillage) of field pea (Pisum sativum) and faba bean (Vicia faba) green manures on soil properties and spring wheat (Triticum aestivum) performance were measured in 2009 and 2010. Faba bean did not establish well and failed as a green manure crop. Termination timing and method affected soil properties in the first year, but did not affect wheat yield significantly. Wheat yield was equivalent in the rolled and mowed treatments to the tilled treatment, indicating field pea termination without incorporation does not inhibit wheat yield under moist conditions. Soil inorganic N was measured in the spring of 2011 following green manure (field pea/barley [Hordeum vulgare]) termination in 2010 by tillage, rolling, rolling + fall tillage, and mowing at two locations. Inorganic N was highest in the tilled plots at both sites, but effects on 4 wk mineralized N (Nmin) differed between sites. When the green manure C:N was narrow (14:1), tillage resulted in lower Nmin than the other treatments; when the C:N was wider (20:1), tillage resulted in the highest Nmin. These results confirm mineralization rates vary with residue placement and N content. Lastly, the effect of 2 yr of continuous no-tillage (NT) or conventional tillage on available N and P, soil microbial biomass (SMB), and oat (Avena sativa) N and P uptake was measured at one site in 2010. Overall, tillage regime did not affect N and P availability, SMB, or oat nutrient uptake. Microbial biomass C and inorganic N tended to be higher in the NT treatment at 0 to 5 cm, suggesting differences may become apparent in the long term. This research confirms that a reduction in tillage is possible in organic systems on the Canadian prairies. The degree of reduction is dependent on the green manure used, soil and climatic factors, and the goals of the producer

Standard model and exotic physics with the top quark at ATLAS

The top quark is the most massive fundamental particle in the Standard Model of particle physics. Only experimentally observed in 1995, it can be used as a precise test of Standard Model predictions, and it could lend insight to the problem of what lies beyond the Standard Model. This thesis presents a measurement of top-quark pair production using data collected at a center-of-mass energy √s=7 TeV in 2011, and a search for production of vector-like quarks using data collected at √s=8 TeV in 2012. Both datasets were recorded by the ATLAS detector, a multipurpose proton-proton collider located at the CERN LHC outside of Geneva Switzerland. The top-quark pair production cross-section is measured as a function of four different variables and the results are presented as normalized, differential spectra. The variables considered are the transverse momentum of the top quark, and the mass, rapidity, and transverse momentum of the top-quark pair system. Events are selected in the lepton+jets channel, and the measured spectra are corrected for detector resolution and efficiency. The final results are compared with predictions from various Monte Carlo generators, theoretical calculations and proton parton distribution functions and found to be in reasonable agreement. Data is found to be softer than all predictions, particularly for high values of top-quark transverse momentum and the top-quark pair invariant mass. The search for vector-like quarks focuses on new heavy quarks that decay with a large branching ratio to a Z boson and a third generation Standard Model quark. Events are selected with at least two leptons (electrons or muons), and two of the leptons are required to reconstruct a Z boson with high transverse momentum. No significant excess of events is observed above the Standard Model prediction. Upper limits on the masses of vector-like T and B quarks are derived for various branching ratio hypotheses

Governance Challenges of AI-enabled Decentralized Autonomous Organizations: Toward a Research Agenda

The emergence of novel applications using distributed ledger technologies (DLTs) has gathered pace since the introduction of Bitcoin and the subsequent release of the Ethereum platform for decentralized applications (dApps). Such decentrally governed DLT systems are accelerating the displacement of intermediaries in regulated contexts such as the financial system and challenging the efficacy of governance regimes that have conventionally levered governance controls on identifiable, accountable decision-makers. The governance challenges of DLT systems are exacerbated by the arrival of digital autonomous organizations (DAOs) that use on-ledger decision-making mechanisms to further displace or eliminate human decision-makers. When DAOs are augmented with artificial intelligence (AI), their potent combination of computational power and access to large on-platform data sets and resources, signals a significant disruption to conventional institutional, regulatory, and legal governance regimes. This paper discusses the governance challenges of AI-enabled DAOs and presents a research agenda to address these challenges

A test to measure the reliability of imagery in grades four and five.

Thesis (Ed.M.)--Boston Universit

Quantitative Susceptibility Mapping by Inversion of a Perturbation Field Model: Correlation With Brain Iron in Normal Aging

There is increasing evidence that iron deposition occurs in specific regions of the brain in normal aging and neurodegenerative disorders such as Parkinson's, Huntington's, and Alzheimer's disease. Iron deposition changes the magnetic susceptibility of tissue, which alters the MR signal phase, and allows estimation of susceptibility differences using quantitative susceptibility mapping (QSM). We present a method for quantifying susceptibility by inversion of a perturbation model, or “QSIP.” The perturbation model relates phase to susceptibility using a kernel calculated in the spatial domain, in contrast to previous Fourier-based techniques. A tissue/air susceptibility atlas is used to estimate B[subscript 0] inhomogeneity. QSIP estimates in young and elderly subjects are compared to postmortem iron estimates, maps of the Field-Dependent Relaxation Rate Increase, and the L1-QSM method. Results for both groups showed excellent agreement with published postmortem data and in vivo FDRI: statistically significant Spearman correlations ranging from Rho=0.905 to Rho=1.00 were obtained. QSIP also showed improvement over FDRI and L1-QSM: reduced variance in susceptibility estimates and statistically significant group differences were detected in striatal and brainstem nuclei, consistent with age-dependent iron accumulation in these regions.National Institutes of Health (U.S.) (Grant P41EB015902)National Institutes of Health (U.S.) (Grant P41RR013218)National Institutes of Health (U.S.) (Grant P41EB015898)National Institutes of Health (U.S.) (Grant P41RR019703)National Institutes of Health (U.S.) (Grant T32EB0011680-06)National Institutes of Health (U.S.) (Grant K05AA017168)National Institutes of Health (U.S.) (Grant R01AA012388

U.S. Foreign Assistance to Latin America and the Caribbean

This report concerns the trends in U.S. assistance to the Latin America and Caribbean region generally reflect the trends and rationales for U.S. foreign aid programs globally. Aid to the region increased during the 1960's with the Alliance for Progress and during the 1980s with aid to Central America. Since 2000, aid levels have increased, especially in the Andean region as the focus has shifted from Cold War issues to counternarcotics and security assistance. Current aid levels to Latin America and the Caribbean comprise about 11.8% of the worldwide FY2006 bilateral aid budget. Amounts requested for FY2007 would reduce this ratio to 10.6%

111th Congress

This report covers the North American Free Trade Agreement (NAFTA), and U.S.-Mexico drug trafficking. It also looks at migration, environmental issues, legislation in the 111th Congress, and the relationship between the Obama Administration and Mexico