A proposed approach to the application of nonlinear irreversible thermodynamics to fracture in composite materials

The fracture criteria upon which most fracture mechanics is based involves an energy balance that is not appropriate for the fracture mechanics of viscoelastic materials such as polymer matrix composites. A more appropriate criterion based upon nonequilibrium thermodynamics and involving a power balance rather than an energy balance is proposed. This crierion is based upon a reformulation of the second law of thermodynamics which focuses attention on the total Legendre transform of energy expressed as a functional over time and space. This excess energy functional can be shown to be equivalent to the Rice J integral if the only irreversible process is the propogation of a single crack completely through the thickness of the specimen and if the crack propogation is assured to be independent of time. For the more general case of more than one crack in a viscoelastic medium integration over both time and space is required. Two experimentally measurable parameters are proposed which should permit the evaluation of this more general fracture criterion

Thermal, Mechanical, and Rehealing Properties of Cross-linked Ionene Networks

Polymers which contain ionic liquid groups have numerous applications in a wide variety of fields. Past research from our group has shown that IL-containing polymers which exist in covalently crosslinked networks can exhibit good ionic conductivities despite the hindrance in polymer chain mobility and relaxation. In part one of this thesis, efforts to create ionic networks which have the capability of being rehealed after exposure to an external stimulus are discussed. Thermoreversible maleimide-furan chemistry was incorporated into an imidazolium-containing ionene network. Maleimide-terminated, imidazolium-containing monomers were coupled with furan-functionalized monomers, prepared from commercially available multifunctional acrylates. Thermal, mechanical and rheological characterization of the networks will be presented and discussed. In the second part of the thesis, the use of thiol-yne photopolymerization as a way to prepare new ionene networks is explained. A series of imidazolium-based bis(trifluoromethylsulfonyl)imide [NTf2] ionene networks were prepared by using thiol-yne ‘click’ photopolymerization to crosslink bisalkynylimidazolium [NTf2] monomers with pentaerythritol tetrakis(3-mercaptopropionate) (PTMP). The thiol:yne molar ratio was varied in order to examine changes in the thermal and mechanical properties of the resulting polymer networks. Photorheology was utilized to determine the approximate gel points for each of the polymer networks prepared. Crosslink density was the primary factor in changing glass transition temperature and tensile properties of the networks

Laser measuring system accurately locates point coordinates on photograph

Laser activated ultraprecision ranging apparatus interfaced with a computer determines point coordinates on a photograph. A helium-neon gas CW laser provides collimated light for a null balancing optical system. This system has no mechanical connection between the ranging apparatus and the photograph

Why are health care interventions delivered over the internet? : a systematic review of the published literature

Background: As Internet use grows, health interventions are increasingly being delivered online. Pioneering researchers are using the networking potential of the Internet, and several of them have evaluated these interventions. Objective: The objective was to review the reasons why health interventions have been delivered on the Internet and to reflect on the work of the pioneers in this field in order to inform future research. Methods: We conducted a qualitative systematic review of peer-reviewed evaluations of health interventions delivered to a known client/patient group using networked features of the Internet. Papers were reviewed for the reasons given for using the Internet, and these reasons were categorized. Results: We included studies evaluating 28 interventions plus 9 interventions that were evaluated in pilot studies. The interventions were aimed at a range of health conditions. Reasons for Internet delivery included low cost and resource implications due to the nature of the technology; reducing cost and increasing convenience for users; reduction of health service costs; overcoming isolation of users; the need for timely information; stigma reduction; and increased user and supplier control of the intervention. A small number of studies gave the existence of Internet interventions as the only reason for undertaking an evaluation of this mode of delivery. Conclusions: One must remain alert for the unintended effects of Internet delivery of health interventions due to the potential for reinforcing the problems that the intervention was designed to help. Internet delivery overcomes isolation of time, mobility, and geography, but it may not be a substitute for face-to-face contact. Future evaluations need to incorporate the evaluation of cost, not only to the health service but also to users and their social networks. When researchers report the outcomes of Internet-delivered health care interventions, it is important that they clearly state why they chose to use the Internet, preferably backing up their decision with theoretical models and exploratory work. Evaluation of the effectiveness of a health care intervention delivered by the Internet needs to include comparison with more traditional modes of delivery to answer the following question: What are the added benefits or disadvantages of Internet use that are particular to this mode of delivery

Revitalizing Grammar Instruction for High School Juniors: Toward a Contextual, Student-Driven, and Minimalistic Method

In this thesis, I explore best practices in grammar instruction for high school juniors. Practicing English teachers have been engaging in the great grammar debate for years, essentially arguing if and how grammar is best taught. Thoughts on teaching grammar greatly differ in the professional community, but most scholars call for a middle ground to be sought in the great grammar debate. In other words, very few scholars think traditional methods that isolate grammar instruction from the writing process are best, but even fewer scholars call for teachers to entirely rid their curriculum of all grammar instruction. I conclude that effective grammar instruction is three-tiered: it is contextual, or directly tied to any unit taught; it is student-driven, or reflective of each student group’s specific needs; and it is minimalistic, or slim in the number of skills that should be taught in one school year. In the second chapter, I identify the target student group, my own high school juniors, and its needs, using text from student essays to show the variety in student ability when it comes to grammar usage. I also identify how the ACT and Common Core Standards serve as baseline tools for the junior-level English teacher in determining what juniors need in terms of instruction. Though the ACT is not the only standardized test juniors across the nation take, it is nationally recognized by all colleges and universities and is heavily used in the Midwest. The Common Core Standards are currently used in nearly all states. In the third chapter, I outline how grammatical instruction can follow the aforementioned three-tiered method by explaining how the instruction can coincide with basic units taught in a junior-level English class. I include appendices of assignments and rubrics that will aid junior-level teachers in assessing students on the subject of grammar

Autobiography as myth of origin

The following PhD thesis will explore the connection between autobiography and myth of origin: On the one hand, I am concerned with the ways in which women autobiographers rewrite classical myths of origin; on the other hand, I contend that autobiography itself is a myth of origin, a recreation of the forces that created the narrator. Throughout this thesis, I will develop two main themes: the first is the use of myth as a framework for autobiographical writing. This is possible because of myth's characteristic double focus on the universal and on the particular version, the historical context. Myth allows feminist autobiographers to connect themselves to universal truths from which they are barred by patriarchal tradition and to carve out their own, highly personal version. The second theme is that the autobiographers depict the origin as the core of the self and utterly Other. First, the narrator has to rely on the stories of other people, or a 'family memory'. Second, the past can be seen as connected to or leaving traces in the present; at the same time, it can be completely Other and incompehensible. Third, the autobiographical I is often cut off from her origins, and a constructive return that integrates the past and the present self is only possible through a deliberate act of mythmaking: It is mythmaking and storytelling that provides a connection between self and Other. I hope to make a contribution to feminist theory of autobiography as well as to feminist theory. Reading autobiography as myth of origin approaches the persistent problem of the relationship between the historical author and the autobiographical self. Moreover, I will explore the the specific relation between women and origins, and address the necessity for feminist theory to develop a framework where self and Other are intimately connected

Boosting and predictability of macroeconomic variables : evidence from Brazil

This paper aims to elaborate a treated data set and apply the boosting methodology to monthly Brazilian macroeconomic variables to check its predictability. The forecasting performed here consists in using linear and nonlinear base-learners, as well as a third type of model that has both linear and nonlinear components in the estimation of the variables using the history itself with lag up to 12 periods. The results obtained here through different evaluation approaches point out that, on average, the performance of boosting models using P-Splines as base-learner are the ones that have the best results, especially the methodology with two components: two-stage boosting. Finally, we perform alternative methods to check the robustness of the results.Este trabalho visa elaborar um conjunto de dados tratados e aplicar a metodologia L2Boosting às variáveis macroeconômicas mensais brasileiras selecionadas para verifcar sua previsibilidade. A previsão aqui realizada consiste no uso de estimações de base lineares e não lineares, assim como um terceiro tipo de modelo que tem componentes lineares e não lineares na estimativa das variáveis usando o próprio histórico com defasagem de até 12 períodos. Os resultados obtidos aqui através de diferentes abordagens de avaliação apontam que, em média, o desempenho dos modelos de boosting usando P-Splines como base-learner são os que têm os melhores resultados, especialmente a metodologia com dois componentes: o boosting em dois estágios. Finalmente, realizamos métodos alternativos para verifcar a robustez dos resultados

Oral health awareness and care preferences in patients with diabetes : a qualitative study

Background People with type 2 diabetes have an increased risk of oral health problems; however, oral health is currently not included in structured diabetes reviews and education in the UK. Aim and Objectives This study explores the patient experience related to oral health and diabetes, especially in relation to: • Awareness of the link between oral health and diabetes and oral self care needs • Interaction with health professionals in dental and general practice • Preferences for receiving oral health information and education Methods This nested qualitative study involved semi-structured telephone interviews with a purposive sample of 20 participants from a questionnaire study on oral health awareness in patients with diabetes. Interview transcripts were analysed using a thematic framework approach. Results Participants were mostly unaware of the link between oral health and diabetes. Those that had been made aware by a health professional were not given concrete self care advice. Interactions with dental professionals were often limited to informing the dental practice of their diagnosis and current medication. Most participants were in favour of dentists screening for diabetes, but as their general practice was the hub for diabetes care, they felt GPs or nurses should provide oral health information and discuss oral health with patients. Conclusions Written information regarding diabetes and its possible effects on oral health needs to be more readily available to people with diabetes, especially at diagnosis. There may be a place for introducing a structured oral health question in routine diabetes reviews