A fast Fourier transform approach to dislocation-based polycrystal plasticity

Polycrystalline materials serve as a basis for much of our current technology and will undoubtedly continue to serve a similar role in the future. Their mechanical properties depend not only on intragranular interactions between various defects, including the distribution of sizes and orientations of the grains, but also interactions with the grain boundaries. Modeling the mechanical behavior of polycrystals has become a standard part of the multiscale treatment of deformation. Currently, polycrystalline simulations are done through crystal plasticity methods, which are often informed through elastically isotropic single-crystal dislocation dynamics studies. These single-crystal studies, however, miss out on crucial effects due to the presence of grain boundaries, and as such, a corrective factor has to be taken when applying the output to higher-scale methods. In addition, these studies are generally done under an assumption of isotropic elasticity, due to the computational expense incurred when including anisotropic calculations. I have developed a Fourier transform-based spectral method that allows for the simulation of the evolution defects, such as dislocations, in heterogeneous systems. This method allows for a more accurate understanding of the interplay between defects and their environment, and will have the capability to determine more accurate constitutive laws for the deformation of polycrystals, to be fed into crystal plasticity models

Toward a better understanding of the development of overweight: A study of eating behavior in the natural environment using ecological momentary assessment

Obesogenic eating behavior is driven by a combination of person-specific factors (e.g., individual differences in physiology and attitudes towards food & eating) and environmental factors (e.g., type and amount of foods available). This study used Ecological Momentary Assessment (EMA) via palmtop computers to collect real-time information about participants’ environment, attitudes, and eating patterns to predict overeating (i.e., greater than usual intake during routine meals/snacks, and eating outside of a participant’s normal routine) that could lead to weight gain. The EMA was completed by 43 women of normal weight, who denied any history of an eating disorder. Participants carried a palmtop computer for 7-10 days, which prompted them six times daily to answer questions about eating episodes, including the number of high-calorie foods in the environment, episodes of overeating, and fluctuations in restraint (as measured by efforts to eat less often, less portions, and fewer fattening foods). On average, 29.8% of eating episodes were characterized by self-identified overeating.Hierarchical linear models showed that BMI interacted with the number of high-calorie foods available in the environment to predict the occurrence of overeating (p = .035). Specifically, for individuals with a higher BMI, the probability of overeating was low in the absence of high-calorie foods, but quickly increased as the number of high-calorie foods available increased. For all participants, on days in which overeating occurred, dietary restraint was significantly higher after overeating than before. A significant nonlinear trend in dietary restraint was observed (p = .019), such that restraint began to increase gradually in the hours prior to self-identified overeating, and accelerated as the episode of overeating approached. Restraint reached a peak several hours after overeating. Reminiscent of Schachter’s early work, the eating behavior of heavier individuals is susceptible to environmental cues. Also, dietary restraint appears to have a complex relationship with overeating in that it is unclear whether restraint leads to or results from bouts of over-consumption. In sum, healthy weight control may be facilitated by limiting high-calorie foods in the immediate environment, and by encouraging healthy dietary restraint.Ph.D., Clinical Psychology -- Drexel University, 200

Mineral inclusions in diamonds from Karowe Mine, Botswana: super-deep sources for super-sized diamonds?

Mineral inclusions in diamonds play a critical role in constraining the relationship between diamonds and mantle lithologies. Here we report the first major and trace element study of mineral inclusions in diamonds from the Karowe Mine in north-east Botswana, along the western edge of the Zimbabwe Craton. From a total of 107 diamonds, 134 silicate, 15 oxide, and 22 sulphide inclusions were recovered. The results reveal that 53% of Karowe inclusion-bearing diamonds derived from eclogitic sources, 44% are peridotitic, 2% have a sublithospheric origin, and 1% are websteritic. The dominant eclogitic diamond substrates sampled at Karowe are compositionally heterogeneous, as reflected in wide ranges in the CaO contents (4–16 wt%) of garnets and the Mg# (69–92) and jadeite contents (14–48 mol%) of clinopyroxenes. Calculated bulk rock REEN patterns indicate that both shallow and deep levels of the subducted slab(s) were sampled, including cumulate-like protoliths. Peridotitic garnet compositions largely derive from harzburgite/dunite substrates (~90%), with almost half the garnets having CaO contents <1.8 wt%, consistent with pyroxene-free (dunitic) sources. The highly depleted character of the peridotitic diamond substrates is further documented by the high mean and median Mg# (93.1) of olivine inclusions. One low-Ca garnet records a very high Cr2O3 content (14.7 wt%), implying that highly depleted cratonic lithosphere at the time of diamond formation extended to at least 220 km depth. Inclusion geothermobarometry indicates that the formation of peridotitic diamonds occurred along a 39–40 mW/m2 model geotherm. A sublithospheric inclusion suite is established by three eclogitic garnets containing a majorite component, a feature so far unique within the Orapa cluster. These low- and high-Ca majoritic garnets follow pyroxenitic and eclogitic trends of majoritic substitution, respectively. The origin of the majorite-bearing diamonds is estimated to be between 330 to 420 km depth, straddling the asthenosphere–transition zone boundary. This new observation of superdeep mineral inclusions in Karowe diamonds is consistent with a sublithospheric origin for the exceptionally large diamonds from this mine

Preclinical detection of infectivity and disease-specific PrP in blood throughout the incubation period of prion disease.

Variant Creutzfeldt-Jakob disease (vCJD) is a fatal neurodegenerative disorder characterised by accumulation of pathological isoforms of the prion protein, PrP. Although cases of clinical vCJD are rare, there is evidence there may be tens of thousands of infectious carriers in the United Kingdom alone. This raises concern about the potential for perpetuation of infection via medical procedures, in particular transfusion of contaminated blood products. Accurate biochemical detection of prion infection is crucial to mitigate risk and we have previously reported a blood assay for vCJD. This assay is sensitive for abnormal PrP conformers at the earliest stages of preclinical prion disease in mice and precedes the maximum infectious titre in blood. Not only does this support the possibility of screening asymptomatic individuals, it will also facilitate the elucidation of the complex relationship that exists between the ensemble of abnormal PrP conformers present in blood and the relationship to infectivity

Learning about IT and learning using IT - A review of current practice on Higher Education AEC Programmes in Ireland

There is a debate concerning the appropriate extent, content and delivery of IT education for AEC programmes. The aim of the research work described in this paper was to generate information to assist the debate, specifically in Ireland, but the results and conclusions may also be of relevance to other countries. A survey of the relevant Heads of Academic Departments in the Universities and Institutes of Technology was carried out in June 2006 with a response rate of 89%. The context to this survey has been the relatively unique development of Ireland over the past ten years (population, economy, IT, construction industry, and higher education) in comparison to other European countries. The recent implementation of the Irish National Framework of Qualifications (NFQ) and its relationship with the European Qualifications Framework (EQF) for lifelong learning is also an important contextual issue for this research. The survey results include the range of specific software training on the AEC programmes, as well as the extent of inclusion of basic IT training, understanding how computers work, understanding and writing computer programmes, consideration of Building Information Modeling (BIM) and the use of Learning Management Systems (LMS). A further interesting feature of the survey has been the identification of the record number of students on higher education AEC programmes in Ireland

Judicial Review, Irrationality, and the Legitimacy of Merits-Review

The definition of the irrationality ground of judicial review recognises the constitutional principle of the separation of powers, in allowing for judicial control of the executive only very rarely. The author in a previous article in this study found that the courts, on occasions, had intervened in circumstances where administrative decisions arguably were not irrational. To this end, the purpose of this article is to assess the constitutionality of these seemingly low standards of irrationality. The author does so by reference either to the manner of review employed—the use of the proportionality principle, for example—or the context of the administrative decision under scrutiny, such as the infringement of the applicant’s fundamental rights. The author finds that the cases from the previous article where low standards of irrationality were arguably adopted were, in fact, legitimate according to these chosen methods of evaluation. However, this is an interim conclusion because, for reasons of word length, the author is unable to complete a full assessment here. It is therefore proposed that a subsequent article will continue to examine the constitutionality of these cases. Furthermore, the author will also try and establish a zone of executive decision-making, for reasons of democracy, where the courts are excluded from irrationality review. If the author is unsuccessful in this regard, the final conclusion of this study will inevitably be that low standards of judicial intervention exist without limit—a clear assault on the constitutional principle stated above