758 research outputs found

    Computer Modeling of Non-Isothermal Crystallization

    Get PDF
    A realistic computer model for simulating isothermal and non-isothermal phase transformations proceeding by homogeneous and heterogeneous nucleation and interface-limited growth is presented. A new treatment for particle size effects on the crystallization kinetics is developed and is incorporated into the numerical model. Time-dependent nucleation rates, size-dependent growth rates, and surface crystallization are also included. Model predictions are compared with experimental measurements of DSC/DTA peak parameters for the crystallization of lithium disilicate glass as a function of particle size, Pt doping levels, and water content. The quantitative agreement that is demonstrated indicates that the numerical model can be used to extract key kinetic data from easily obtained calorimetric data. The model can also be used to probe nucleation and growth behavior in regimes that are otherwise inaccessible. Based on a fit to data, an earlier prediction that the time-dependent nucleation rate in a DSC/DTA scan can rise above the steady-state value at a temperature higher than the peak in the steady-state rate is demonstrated

    Social identity mapping online.

    Get PDF
    This is the author accepted manuscript Social identities play an important role in many aspects of life, not least in those pertaining to health and well-being. Decades of research shows that these relationships are driven by a range of social identity processes, including identification with groups, social support received from groups, and multiple group memberships. However, to date, researchers have not had access to methods that simultaneously capture these social identity processes. To fill this void, this article introduces an online Social Identity Mapping (oSIM) tool designed to assess the multidimensional and connected nature of social identities. Four studies (total N = 721) featuring community, student, new parent, and retiree samples, test the reliability and validity of oSIM. Results indicate that the tool is easy to use, engaging, has good internal consistency as well as convergent and discriminant validity, and predicts relevant outcomes across a range of contexts. Furthermore, using meta-analytic findings, the tool is able to index a higher-order social identity construct, here introduced as a supergroup. This new concept provides holistic information about groups (reflecting an integrated index of several social identity processes) that are predictive of well-being outcomes, as well as outcomes related to successful adjustment to challenging life events. We discuss how the tool can be used to tackle key debates in the literature and contribute to theory by affording researchers the opportunity to capture the nuanced and contextual nature of social identity in action.Australian Research Counci

    The impact of genetic counselling about breast cancer risk on women's risk perceptions and levels of distress

    Get PDF
    Women referred to a familial breast cancer clinic completed questionnaires before and after counselling and at annual follow-up to assess their risk estimate and psychological characteristics. The aims were to determine whether those who attended the clinic overestimated their risk or were highly anxious and whether counselling influenced risk estimates and levels of distress. Women (n = 450) at this clinic were more likely to underestimate (39%) than overestimate (14%) their risk. Mean trait anxiety scores were higher than general population data (t = 4.9, n = 1059, P < 0.001) but not significantly different from published data from other screening samples. Overestimators (z = 5.69, P < 0.0001) and underestimators (z = –8.01, P < 0.0001) reported significantly different risk estimates (i.e. increased accuracy) after counselling, but significant inaccuracies persisted. Over- (n = 12) and underestimators (n = 60) were still inaccurate in their risk estimates by a factor of 2 after counselling. Thirty per cent of the sample scored above the cut-off (5/6) for case identification on a screening measure for psychological distress, the General Health Questionnaire (GHQ). GHQ scores were significantly lower after counselling (t = 3.6, d.f. = 384, P = 0.0004) with no evidence of increasing risk estimate causing increased distress. The risk of distress after counselling was greater for younger women and those who were more distressed at first presentation. The counselling offered was effective in increasing the accuracy of risk perceptions without causing distress to those who initially underestimated their risk. It is worrying that inaccuracies persisted, particularly as the demand for service has since reduced the consultation time offered in this clinic. Further work is needed to evaluate alternative models of service delivery using more sophisticated methods of assessing understanding of risk. © 1999 Cancer Research Campaig

    A randomised controlled trial of a psychoeducational intervention for women at increased risk of breast cancer

    Get PDF
    This study aimed to compare the impact of two versions of a psychoeducational written intervention on cancer worry and objective knowledge of breast cancer risk-related topics in women who had been living with an increased risk of familial breast cancer for several years. Participants were randomised to three conditions: scientific and psychosocial information pack (Group 1), scientific information pack only (Group 2) or standard care control (Group 3). They completed postal questionnaires at baseline (n¼163) and\ud 4 weeks (n¼151). As predicted, there was a significant decrease in cancer worry for Group 1, but not Group 2. Objective\ud knowledge significantly improved for both Group 1 and Group 2 as expected, but not Group 3. However, there was an unpredicted\ud decline in cancer worry for Group 3. This study supports the value of a scientific and psychosocial information pack in providing up-to-date information related to familial risk of breast cancer for long-term attendees of a familial breast cancer clinic. Further research is warranted to determine how the information pack could be incorporated into the existing clinical service, thus providing these\ud women with the type of ongoing psychosocial support that many familial breast cancer clinics are currently lacking
    • …
    corecore