Existence of Hamiltonians for Some Singular Interactions on Manifolds

The existence of the Hamiltonians of the renormalized point interactions in two and three dimensional Riemannian manifolds and that of a relativistic extension of this model in two dimensions are proven. Although it is much more difficult, the proof of existence of the Hamiltonian for the renormalized resolvent for the non-relativistic Lee model can still be given. To accomplish these results directly from the resolvent formula, we employ some basic tools from the semigroup theory.Comment: 33 pages, no figure

Relation of age and sex with carotid intima media thickness in healthy children

Background/aim: To investigate the age- and sex-associated carotid intima media thickness (cIMT) changes in healthy children to determine the age- and sex-specific normal range of values for childhood. Materials and methods: This study examined 91 healthy school-age children aged 7-15 years prospectively. Standardized sonographic cIMT measurements and analyses were performed. Body mass index and blood pressure were obtained, and atherosclerotic risk factors were investigated. Age- and sex-specific cIMT measurements for different age groups were calculated and the relation with sex was investigated. Results: Regarding the total study group, mean cIMT measurements for age groups 7-9, 10-12, and 13-15 years were 4.1 ± 0.5 mm, 4.4 ± 0.6 mm, and 4.6 ± 0.4 mm, respectively. cIMT did not differ between boys and girls in the same age group. Age related analyses showed significant variations among the age groups with positive correlation between cIMT and age. Conclusion: Our results suggest that age-related physiologic thickening of the carotid artery intima-media occurs not only in adults but also in children and that sex is not a factor for cIMT differences in childhood. © TÜBİTAK

Incommensurate Magnetic Fluctuations in YBa2Cu3O6.6

We use inelastic neutron scattering to demonstrate that at low temperatures, the low frequency magnetic fluctuations in YBa_2Cu_3O_{6.6} ($T_c=62.7$ K) are incommensurate, being found at positions displaced by $\pm\delta$ ($0.057\pm 0.006$ r.l.u.) along the $[\pi,\pi]$ direction from the wave vector $(\pi,\pi)$ associated with the antiferromagnetic order of the parent insulator, YBa_2Cu_3O_{6}. The dynamical susceptibility $\chi''(q,\omega)$ at the incommensurate positions increases on cooling below $T_c$, accompanied by a suppression of magnetic fluctuations at the commensurate points.Comment: 11 pages, Latex, 4 figure

Asteroseismic modelling of the metal-poor star Tau Ceti

Context. Asteroseismology is an effcient tool not only for testing stellar structure and evolutionary theory but also constraining the parameters of stars for which solar-like oscillations are detected, presently. As an important southern asteroseismic target, Tau Ceti, is a metal-poor star. The main features of the oscillations and some frequencies of ? Ceti have been identified. Many scientists propose to comprehensively observe this star as part of the Stellar Observations Network Group. Aims. Our goal is to obtain the optimal model and reliable fundamental parameters for the metal-poor star Tau Ceti by combining all non-asteroseismic observations with these seismological data. Methods. Using the Yale stellar evolution code (YREC), a grid of stellar model candidates that fall within all the error boxes in the HR diagram have been constructed, and both the model frequencies and large- and small- frequency separations are calculated using the Guenther's stellar pulsation code. The \chi2c minimization is performed to identify the optimal modelling parameters that reproduce the observations within their errors. The frequency corrections of near-surface effects to the calculated frequencies using the empirical law, as proposed by Kjeldsen and coworkers, are applied to the models. Results. We derive optimal models, corresponding to masses of about 0.775 - 0.785 M? and ages of about 8 - 10 Gyr. Furthermore, we find that the quantities derived from the non-asteroseismic observations (effective temperature and luminosity) acquired spectroscopically are more accurate than those inferred from interferometry for ? Ceti, because our optimal models are in the error boxes B and C, which are derived from spectroscopy results.Comment: 8 pages, 5 figures, accepted by A&

Open issues in probing interiors of solar-like oscillating main sequence stars 1. From the Sun to nearly suns

We review some major, open issues in the current modelling of low and intermediate mass, main sequence stars based on seismological studies. In the present paper, the solar case is discussed together with current problems that are common to the Sun and stars with a structure similar to that of the Sun. Several additional issues specific to main sequence stars other than the Sun are reviewed and illustrated with a few stars observed with CoRoT in a companion paper.Comment: GONG 2010 - SoHO 24, A new era of seismology of the Sun and solar-like stars. To be published in the Journal of Physics: Conference Series (JPCS

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Stock market return and volatility relationship: Monday effect

This paper assesses whether the return-volatility relationship is the same on Monday compared to other days. Empirical evidence suggests that the Monday return-volatility relationship is different from the other days for equally and value weighted NYSE, S&P500, AMEX and equally weighted NASDAQ indexes. © International Economic Society

Effects of the evidence-based history teaching on Turkish primary students' perception of history and related concepts

AbstractThe purpose of this study is to determine the effects of evidence-based history teaching on students’ perception of the history and related concepts. The study was conducted as an action research. A teaching intervention was designed. The main theoretical perspective informing the teaching intervention was evidence-based history teaching. The teaching intervention was put into practice in a 8th grade class consisting of 25 primary students (aged 14-15). It lasted 15 teaching hours. The effectiveness of the teaching intervention was determined by using both a questionnaire consisting of open-ended questions and worksheets used during the teaching intervention. Students completed the same questionnaire, designed by the researchers, prior to and after the teaching intervention. Additionally, students’ works as in the form of worksheets were collected and analysed so as to find out effectiveness of the specific teaching activities. The descriptive and content analyses methods were employed in analysis of data collected. The findings of the study indicated that students’ perceptions on history and related concepts changed as result of evidence-based history teaching used in their courses