175 research outputs found

    The Synthesis and Testing of Highly Strained Cyclic and Polycyclic Molecules as Hypergolic Fuels

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    Increasing fuel efficiency has been a goal for chemists for several decades. Particularly, a more efficient fuel can increase the range of liquid-hydrocarbon-fueled ram-jets and cruise missiles. A storable high-energy fuel that spontaneously ignites upon addition of an oxidizer is defined as a hypergolic fuel. Hypergolic storable fuels provide an increase in energy per unit volume of fuel and eliminate the need for an external ignition system. Several classes of functionalized hydrocarbons such as amines, boranes, and phosphines are known to be hypergolic with nitric acid oxidizers, but only hydrazine and its simple derivatives5 have been found to exhibit true hypergolic behavior with H2O2. Hydrogen peroxide is a good candidate for an oxidizer due to its reduced toxicity and improved storage capability. Hydrazine-based fuels are expensive, highly corrosive, and toxic, thus providing the need for investigation of other fuels that may be hypergolic with H2O2. Strained hydrocarbons have been studied as high-density fuels. Some examples including benzvalene and cubane, exhibit an increase in heat of combustion as the density of the fuel increases. Many conventional hydrocarbon fuels, such as JP-5 and JP-10, show a decrease in heat of combustion as density of the fuel increases. Strained hydrocarbons can therefore increase the range of the missile by increasing the combustion efficiency per volume of fuel. The goal of this research is to investigate hypergolic behavior of strained hydrocarbons by adding an amine functional group which has been found to hypergolic with nitric acid oxidizers. N,N-Dimethyl-[3]-triangulane-7-methylamine (l), cyclopropylamines (2), cyclobutylamines (3), propylamines (4), and butylamines (5) were synthesized and investigated. The amino group should react with oxygen, providing the initiation step for ring decomposition. The highly exothermic reactions will accumulate energy and potentially lead to spontaneous ignition of the fuel. Triangulanes possess high strain energy, while the less strained cyclopropane and cyclobutanes are more volatile and may show shorter ignition times

    Strengthening evaluation and implementation by specifying components of behaviour change interventions: a study protocol.

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    BACKGROUND: The importance of behaviour change in improving health is illustrated by the increasing investment by funding bodies in the development and evaluation of complex interventions to change population, patient, and practitioner behaviours. The development of effective interventions is hampered by the absence of a nomenclature to specify and report their content. This limits the possibility of replicating effective interventions, synthesising evidence, and understanding the causal mechanisms underlying behaviour change. In contrast, biomedical interventions are precisely specified (e.g., the pharmacological 'ingredients' of prescribed drugs, their dose and frequency of administration). For most complex interventions, the precise 'ingredients' are unknown; descriptions (e.g., 'behavioural counseling') can mean different things to different researchers or implementers. The lack of a method for specifying complex interventions undermines the precision of evidence syntheses of effectiveness, posing a problem for secondary, as well as primary, research.We aim to develop a reliable method of specifying intervention components ('techniques') aimed at changing behaviour. METHODS/DESIGN: The research will be conducted in three phases. The first phase will develop the nomenclature. We will refine a preliminary list of techniques and definitions. Using a formal consensus method, experts will then define the key attributes of each technique and how it relates to, and differs from, others. They will evaluate the techniques and their definitions until they achieve an agreed-upon list of clearly defined, nonredundant techniques. The second phase will test the nomenclature. Trained experts (primary researchers and systematic reviewers), equipped with a coding manual and guidance, will use the nomenclature to code published descriptions of complex interventions. Reliability between experts, over time, and across types of users will be assessed. We will assess whether using the nomenclature to write intervention descriptions enhances the clarity and replicability of interventions. The third phase will develop a web-based users' resource of clearly specified and nonredundant techniques, which will aid the scientific understanding of, and development of, effective complex interventions. Dissemination throughout the project will be through stakeholder meetings, targeted multidisciplinary workshops, conference presentation, journal publication, and publication in an interactive web-based platform (a Wiki). DISCUSSION: The development of a reliable method of specifying intervention components aimed at changing behaviour will strengthen the scientific basis for developing, evaluating, and reporting complex interventions. It will improve the precision of evidence syntheses of effectiveness, thus enhancing secondary, as well as primary, research.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

    Family- and school-based correlates of energy balance-related behaviours in 10-12-year-old children: a systematic review within the ENERGY (EuropeaN Energy balance Research to prevent excessive weight Gain among Youth) project

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    Objective: To identify family- and school-based correlates of specific energy balance-related behaviours (physical activity, sedentary behaviour, breakfast consumption, soft drink consumption) among 10-12-year-olds, using the EnRG framework (Environmental Research framework for weight Gain prevention). Design: A literature review to identify observational studies exploring at least one family- or school-based correlate of the specific behaviours, resulting in seventy-six articles. Setting: Eighteen studies were conducted in Europe, forty-one studies in North America and seventeen studies in Australasia. Subjects: Healthy children aged 10-12 years. Results: Parental and maternal physical activity, doing physical activities with parents and parental logistic support were identified as the most important, positive correlates of physical activity. Parental rules was the most important correlate of sedentary behaviour and was inversely related to it. School socioeconomic status was positively related to physical activity and inversely related to sedentary behaviour. The available studies suggested a positive relationship between soft drink availability at home and consumption. Soft drink availability and consumption at school were the most important school-based correlates of soft drink consumption. A permissive parenting style was related to more soft drink consumption and less breakfast consumption. Conclusions: An important role has been awarded to parents, suggesting parents should be involved in obesity prevention programmes. Despite the opportunities a school can offer, little research has been done to identify school-environmental correlates of energy balance-related behaviours in this age group. Obesity prevention programmes can focus on the most important correlates to maximize the effectiveness of the programme. Future research should aim at longitudinal studies

    Experiencing fear appeals as a challenge or a threat influences attainment value and academic self-efficacy

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    © 2015 Elsevier Ltd. Fear appeals are persuasive messages that highlight the negative consequences of a particular course of action. Studies have shown that attainment value and academic self-efficacy predict how fear appeals are appraised. In this study we examined how the appraisal of fear appeals might also influence subsequent attainment value and academic self-efficacy. Self-report data were collected from 1433 students in their final two years of secondary education over three waves. Findings revealed that when students saw fear appeals as a challenge attainment value and academic self-efficacy were higher. When students saw fear appeals as a threat, attainment value and academic self-efficacy were lower. These results highlight the functional importance of how fear appeals are appraised. Challenge and threat appraisals were not mere by products of attainment value or academic self-efficacy but impacted on attainment value and academic self-efficacy; variables that are likely to make a critical impact on educational progress and attainment. We conclude that initial teacher education and teacher professional development programs would benefit from enhanced interpersonal and relational-skills training to enable teachers to judge more effectively how fear appeals are appraised

    Can programme theory be used as a 'translational tool’ to optimise health service delivery in a national early years’ initiative in Scotland: a case study

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    Background Theory-based evaluation (TBE) approaches are heralded as supporting formative evaluation by facilitating increased use of evaluative findings to guide programme improvement. It is essential that learning from programme implementation is better used to improve delivery and to inform other initiatives, if interventions are to be as effective as they have the potential to be. Nonetheless, few studies describe formative feedback methods, or report direct instrumental use of findings resulting from TBE. This paper uses the case of Scotland’s, National Health Service, early years’, oral health improvement initiative (Childsmile) to describe the use of TBE as a framework for providing feedback on delivery to programme staff and to assess its impact on programmatic action.<p></p> Methods In-depth, semi-structured interviews and focus groups with key stakeholders explored perceived deviations between the Childsmile programme 'as delivered’ and its Programme Theory (PT). The data was thematically analysed using constant comparative methods. Findings were shared with key programme stakeholders and discussions around likely impact and necessary actions were facilitated by the authors. Documentary review and ongoing observations of programme meetings were undertaken to assess the extent to which learning was acted upon.<p></p> Results On the whole, the activities documented in Childsmile’s PT were implemented as intended. This paper purposefully focuses on those activities where variation in delivery was evident. Differences resulted from the stage of roll-out reached and the flexibility given to individual NHS boards to tailor local implementation. Some adaptations were thought to have diverged from the central features of Childsmile’s PT, to the extent that there was a risk to achieving outcomes. The methods employed prompted national service improvement action, and proposals for local action by individual NHS boards to address this.<p></p> Conclusions The TBE approach provided a platform, to direct attention to areas of risk within a national health initiative, and to agree which intervention components were 'core’ to its hypothesised success. The study demonstrates that PT can be used as a 'translational tool’ to facilitate instrumental use of evaluative findings to optimise implementation within a complex health improvement programme.<p></p&gt

    How behavioural science can contribute to health partnerships: The case of The Change Exchange

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    © 2017 The Author(s). Background: Health partnerships often use health professional training to change practice with the aim of improving quality of care. Interventions to change practice can learn from behavioural science and focus not only on improving the competence and capability of health professionals but also their opportunity and motivation to make changes in practice. We describe a project that used behavioural scientist volunteers to enable health partnerships to understand and use the theories, techniques and assessments of behavioural science. Case studies: This paper outlines how The Change Exchange, a collective of volunteer behavioural scientists, worked with health partnerships to strengthen their projects by translating behavioural science in situ. We describe three case studies in which behavioural scientists, embedded in health partnerships in Uganda, Sierra Leone and Mozambique, explored the behaviour change techniques used by educators, supported knowledge and skill development in behaviour change, monitored the impact of projects on psychological determinants of behaviour and made recommendations for future project developments. Discussion: Challenges in the work included having time and space for behavioural science in already very busy health partnership schedules and the difficulties in using certain methods in other cultures. Future work could explore other modes of translation and further develop methods to make them more culturally applicable. Conclusion: Behavioural scientists could translate behavioural science which was understood and used by the health partnerships to strengthen their project work

    Control-Value Appraisals, Enjoyment, and Boredom in Mathematics:A Longitudinal Latent Interaction Analysis

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    Based on the control-value theory of achievement emotions, this longitudinal study examined students' control-value appraisals as antecedents of their enjoyment and boredom in mathematics. Self-report data for appraisals and emotions were collected from 579 students in their final year of primary schooling over three waves. Data were analyzed using latent interaction structural equation modeling. Control-value appraisals predicted emotions interactively depending on which specific subjective value was paired with perceived control. Achievement value amplified the positive relation between perceived control and enjoyment, and intrinsic value reduced the negative relation between perceived control and boredom. These longitudinal findings demonstrate that control and value appraisals, and their interaction, are critically important for the development of students' enjoyment and boredom over time

    Supporting genetics in primary care: investigating how theory can inform professional education

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    Evidence indicates that many barriers exist to the integration of genetic case finding into primary care. We conducted an exploratory study of the determinants of three specific behaviours related to using breast cancer genetics referral guidelines effectively: 'taking a family history', 'making a risk assessment', and 'making a referral decision'. We developed vignettes of primary care consultations with hypothetical patients, representing a wide range of genetic risk for which different referral decisions would be appropriate. We used the Theory of Planned Behavior to develop a survey instrument to capture data on behavioural intention and its predictors (attitude, subjective norm, and perceived behavioural control) for each of the three behaviours and mailed it to a sample of Canadian family physicians. We used correlation and regression analyses to explore the relationships between predictor and dependent variables. The response rate was 96/125 (77%). The predictor variables explained 38-83% of the variance in intention across the three behaviours. Family physicians' intentions were lower for 'making a risk assessment' (perceived as the most difficult) than for the other two behaviours. We illustrate how understanding psychological factors salient to behaviour can be used to tailor professional educational interventions; for example, considering the approach of behavioural rehearsal to improve confidence in skills (perceived behavioural control), or vicarious reinforcement as where participants are sceptical that genetics is consistent with their role (subjective norm)

    Teacher Use of Loss-Focused, Utility Value Messages, Prior to High-Stakes Examinations, and Their Appraisal by Students

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    This study set out to assess a new instrument designed to measure the perceived frequency that teachers use fear appeals (communicated value messages that focus on avoiding failure) prior to a high-stakes examination and their appraisal as a challenge or a threat. Data were collected from two samples of students preparing for their high-stakes school exit examinations. Exploratory and confirmatory factor analyses supported a three-factor structure of message frequency, challenge, and threat appraisal. Challenge appraisal positively correlated with value, academic self-efficacy, and engagement. Threat appraisal negatively correlated with academic self-efficacy and engagement. Message frequency was unrelated to value, academic self-efficacy, and engagement. The critical factor in determining relations with antecedents and outcomes is not the message frequency but how it is appraised

    Evaluation of polygenic risk scores for breast and ovarian cancer risk prediction in BRCA1 and BRCA2 mutation carriers

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    Background: Genome-wide association studies (GWAS) have identified 94 common single-nucleotide polymorphisms (SNPs) associated with breast cancer (BC) risk and 18 associated with ovarian cancer (OC) risk. Several of these are also associated with risk of BC or OC for women who carry a pathogenic mutation in the high-risk BC and OC genes BRCA1 or BRCA2. The combined effects of these variants on BC or OC risk for BRCA1 and BRCA2 mutation carriers have not yet been assessed while their clinical management could benefit from improved personalized risk estimates. Methods: We constructed polygenic risk scores (PRS) using BC and OC susceptibility SNPs identified through population-based GWAS: for BC (overall, estrogen receptor [ER]-positive, and ER-negative) and for OC. Using data from 15 252 female BRCA1 and 8211 BRCA2 carriers, the association of each PRS with BC or OC risk was evaluated using a weighted cohort approach, with time to diagnosis as the outcome and estimation of the hazard ratios (HRs) per standard deviation increase in the PRS. Results: The PRS for ER-negative BC displayed the strongest association with BC risk in BRCA1 carriers (HR = 1.27, 95% confidence interval [CI] = 1.23 to 1.31, P = 8.2 x 10(53)). In BRCA2 carriers, the strongest association with BC risk was seen for the overall BC PRS (HR = 1.22, 95% CI = 1.17 to 1.28, P = 7.2 x 10(-20)). The OC PRS was strongly associated with OC risk for both BRCA1 and BRCA2 carriers. These translate to differences in absolute risks (more than 10% in each case) between the top and bottom deciles of the PRS distribution; for example, the OC risk was 6% by age 80 years for BRCA2 carriers at the 10th percentile of the OC PRS compared with 19% risk for those at the 90th percentile of PRS. Conclusions: BC and OC PRS are predictive of cancer risk in BRCA1 and BRCA2 carriers. Incorporation of the PRS into risk prediction models has promise to better inform decisions on cancer risk management
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