Experimental pool boiling investigations of vertical coalescence for FC-72 on silicon from an isolated artificial cavity

In this study bubble growth from an isolated artificial cavity micro-fabricated on a horizontal 380 µm thick silicon wafer was investigated. The horizontally oriented boiling surface was heated by a thin resistance heater integrated on the rear of the silicon test section. The temperature was measured using an integrated micro-sensor situated on the boiling surface with the artificial cavity located in its geometrical centre. A resistive track was used as the sensor, which when calibrated, exhibited a near-linear behaviour with increasing temperature. To conduct pool boiling experiments the test section was immersed in degassed fluorinert FC-72. Bubble nucleation, growth and detachment at different pressures were observed using high-speed imaging. Coalescence was observed at the boundary between the isolated bubble and interference regimes. The occurrence of vertical coalescence was found to be more frequent, with increasing wall superheat and decreasing pressure. The equivalent sphere volumes of two bubbles before and after coalescence were evaluated from area measurements. It was observed that the second nucleated bubble is always smaller than its predecessor. The vapour generation appears not to stop during coalescence as the volume of the merged bubble was typically 5-18% larger than the sum of the bubble volumes just before coalescence

Underwriting Apophenia and Cryptids: Are Cycles Statistical Figments of our Imagination?

This paper re-examines the evidence in favour of the existence of underwriting cycles in property and casualty insurance and their economical significance. Using a meta-analysis of published papers in the area of insurance economics, we show that the evidence supporting the existence of underwriting cycles is misleading. There is, in fact, little evidence in favour of insurance cycles with a linear autoregressive character. This means that any cyclicality in firm profitability in the property and casualty insurance industry is not predictable in a classical econometric framework. It follows that pricing in the property and casualty insurance industry is not incompatible with that of a competitive market

Meaning behind measurement : self-comparisons affect responses to health related quality of life questionnaires

Purpose The subjective nature of quality of life is particularly pertinent to the domain of health-related quality of life (HRQOL) research. The extent to which participants’ responses are affected by subjective information and personal reference frames is unknown. This study investigated how an elderly population living with a chronic metabolic bone disorder evaluated self-reported quality of life. Methods Participants (n = 1,331) in a multi-centre randomised controlled trial for the treatment of Paget’s disease completed annual HRQOL questionnaires, including the SF-36, EQ-5D and HAQ. Supplementary questions were added to reveal implicit reference frames used when making HRQOL evaluations. Twenty-one participants (11 male, 10 female, aged 59–91 years) were interviewed retrospectively about their responses to the supplementary questions, using cognitive interviewing techniques and semi-structured topic guides. Results The interviews revealed that participants used complex and interconnected reference frames to promote response shift when making quality of life evaluations. The choice of reference frame often reflected external factors unrelated to individual health. Many participants also stated that they were unclear whether to report general or disease-related HRQOL. Conclusions It is important, especially in clinical trials, to provide instructions clarifying whether ‘quality of life’ refers to disease-related HRQOL. Information on selfcomparison reference frames is necessary for the interpretation of responses to questions about HRQOL.The Chief Scientist Office of the Scottish Government Health Directorates, The PRISM funding bodies (the Arthritis Research Campaign, the National Association for the Relief of Paget’s disease and the Alliance for Better Bone Health)Peer reviewedAuthor final versio

Time-Based Partitioning Model for Predicting Neurologically Favorable Outcome among Adults with Witnessed Bystander Out-of-Hospital CPA

Background：Optimal acceptable time intervals from collapse to bystander cardiopulmonary resuscitation (CPR) for neurologically favorable outcome among adults with witnessed out-of-hospital cardiopulmonary arrest (CPA) have been unclear. Our aim was to assess the optimal acceptable thresholds of the time intervals of CPR for neurologically favorable outcome and survival using a recursive partitioning model.Methods and Findings：From January 1, 2005 through December 31, 2009, we conducted a prospective population-based observational study across Japan involving consecutive out-of-hospital CPA patients (N = 69,648) who received a witnessed bystander CPR. Of 69,648 patients, 34,605 were assigned to the derivation data set and 35,043 to the validation data set. Time factors associated with better outcomes: the better outcomes were survival and neurologically favorable outcome at one month, defined as category one (good cerebral performance) or two (moderate cerebral disability) of the cerebral performance categories. Based on the recursive partitioning model from the derivation dataset (n = 34,605) to predict the neurologically favorable outcome at one month, 5 min threshold was the acceptable time interval from collapse to CPR initiation; 11 min from collapse to ambulance arrival; 18 min from collapse to return of spontaneous circulation (ROSC); and 19 min from collapse to hospital arrival. Among the validation dataset (n = 35,043), 209/2,292 (9.1%) in all patients with the acceptable time intervals and 1,388/2,706 (52.1%) in the subgroup with the acceptable time intervals and pre-hospital ROSC showed neurologically favorable outcome.Conclusions：Initiation of CPR should be within 5 min for obtaining neurologically favorable outcome among adults with witnessed out-of-hospital CPA. Patients with the acceptable time intervals of bystander CPR and pre-hospital ROSC within 18 min could have 50% chance of neurologically favorable outcome

A demonstration of 'broken' visual space

It has long been assumed that there is a distorted mapping between real and ‘perceived’ space, based on demonstrations of systematic errors in judgements of slant, curvature, direction and separation. Here, we have applied a direct test to the notion of a coherent visual space. In an immersive virtual environment, participants judged the relative distance of two squares displayed in separate intervals. On some trials, the virtual scene expanded by a factor of four between intervals although, in line with recent results, participants did not report any noticeable change in the scene. We found that there was no consistent depth ordering of objects that can explain the distance matches participants made in this environment (e.g. A > B > D yet also A < C < D) and hence no single one-to-one mapping between participants’ perceived space and any real 3D environment. Instead, factors that affect pairwise comparisons of distances dictate participants’ performance. These data contradict, more directly than previous experiments, the idea that the visual system builds and uses a coherent 3D internal representation of a scene

The Organizational Account of Function is an Etiological Account of Function

The debate on the notion of function has been historically dominated by dispositional and etiological accounts, but recently a third contender has gained prominence: the organizational account. This original theory of function is intended to offer an alternative account based on the notion of self-maintaining system. However, there is a set of cases where organizational accounts seem to generate counterintuitive results. These cases involve cross-generational traits, that is, traits that do not contribute in any relevant way to the self-maintenance of the organism carrying them, but instead have very important effects on organisms that belong to the next generation. We argue that any plausible solution to the problem of cross-generational traits shows that the organizational account just is a version of the etiological theory and, furthermore, that it does not provide any substantive advantage over standard etiological theories of function

The development and piloting of the graduate assessment of preparedness for practice (GAPP) questionnaire

Introduction Most new dental graduates in the UK begin their professional career following a year in dental foundation training (DFT). There has been little investigation of how prepared they feel for independent general dental practice across all four domains of the General Dental Council’s curriculum ‘Preparing for practice’. This paper describes the development of the Graduate Assessment of Preparedness for Practice (GAPP) questionnaire to address this. Methodology The GAPP questionnaire was developed and piloted using a cohort of educational supervisors (ESs) and foundation dentists (FDs). The questionnaire comprised three parts, the first of which collected respondent demographic data. The second was based on Preparing for practice and was used to develop 34 ‘competence areas’ and required a tick-box response on a 7‑category Likert Scale. The third comprised free text questions in order to further explore the subject’s responses. Results Pilot feedback was positive, the statements were felt to be clear and unambiguous, allowing them sufficient scope to state their position. The pilot study informed small cosmetic changes to the GAPP questionnaire and inclusion of a ‘comments’ column for respondents to qualify their responses. The pilot results indicated that both FDs and their ESs felt that at ten months of DFT, the FDs were very well prepared for independent general dental practice. Discussion The paper describes the important considerations relating to the reliability and validity of the GAPP questionnaire. Conclusions GAPP appears to be a suitable questionnaire to measure preparedness of new graduates with a degree of reliability and validity. The instrument is designed to be simple to complete and provides a useful analytical instrument for both self-assessment of competence and for wider use within dental education

Profile of subjective quality of life and its correlates in a nation-wide sample of high school students in an Arab setting using the WHOQOL-Bref

<p>Abstract</p> <p>Background</p> <p>The upsurge of interest in the quality of life (QOL) of children is in line with the 1989 Convention on the Rights of the Child, which stressed the child's right to adequate circumstances for physical, mental, and social development. The study's objectives were to: (i) highlight how satisfied Kuwaiti high school students were with life circumstances as in the WHOQOL-Bref; (ii) assess the prevalence of at risk status for impaired QOL and establish the QOL domain normative values; and (iii) examine the relationship of QOL with personal, parental, and socio-environmental factors.</p> <p>Method</p> <p>A nation-wide sample of students in senior classes in government high schools (N = 4467, 48.6% boys; aged 14-23 years) completed questionnaires that included the WHOQOL-Bref.</p> <p>Results</p> <p>Using Cummins' norm of 70% - 80%, we found that, as a group, they barely achieved the well-being threshold score for physical health (70%), social relations (72.8%), environment (70.8%) and general facet (70.2%), but not for psychological health (61.9%). These scores were lower than those reported from other countries. Using the recommended cut-off of <1<it>SD </it>of population mean, the prevalence of at risk status for impaired QOL was 12.9% - 18.8% (population age-adjusted: 15.9% - 21.1%). In all domains, boys had significantly higher QOL than girls, mediated by anxiety/depression; while the younger ones had significantly higher QOL (<it>p </it>< 0.001), mediated by difficulty with studies and social relations. Although poorer QOL was significantly associated with parental divorce and father's low socio-economic status, the most important predictors of poorer QOL were perception of poor emotional relationship between the parents, poor self-esteem and difficulty with studies.</p> <p>Conclusion</p> <p>Poorer QOL seemed to reflect a circumstance of social disadvantage and poor psychosocial well-being in which girls fared worse than boys. The findings indicate that programs that address parental harmony and school programs that promote study-friendly atmospheres could help to improve psychosocial well-being. The application of QOL as a school population health measure may facilitate risk assessment and the tracking of health status.</p

Children’s perspectives on scale response options of subjective well-being measures: A comparison between numerical and verbal-response formats

It is crucial to establish the validity of existing measures of children’s subjective well-being (SWB) for use within specific contexts. Two important measurement issues that implicate the validly of SWB scales are ‘question framing’ and ‘response options’. Fundamental to the latter is the concept of scale granularity, which refers to the number of response options imposed on a scale. However, the majority of studies on the topic have used adult and not child samples. The overarching aim of the study was to explore how children from three different contexts (Catalonia, Cape Town and North-Western Romania) perceive, understand, and make sense of SWB instruments, using focus group interviews and thematic analysis. A key finding of the study was the similarities in children’s understandings of the response options across these contexts. While this does not represent a claim for a ‘universal understanding’ of measurement scale response formats, it is suggesting that there are similar cognitive processes that children across the contexts apply when making sense of and deciding on which response option to endorse (for both verbal and numerical formats)