Hong Kong dentists' preparedness for medical emergency in dental clinics

Aim: The aim of this study was to investigate the Hong Kong dentists’ and dental clinics’ preparedness for medical emergency in the dental clinic. Methods: Two custom designed questionnaires were developed, one for dentists and another for dental clinics, to collect the required information. The sampling frame for participants was the list of registered dentists published by the Hong Kong Dental Council on its website in January 2016. A total of 434 dentists and 143 dental clinics were selected from the list by systematic random sampling. The latter sample was supplemented by 10 randomly selected government dental clinics. The questionnaires were mailed the selected dentists together with a cover letter and a stamped return envelope. A reminder letter and another copy of the questionnaire were sent out two weeks after the first mailing. Results: 167 (38%) completed dentist questionnaires and 53 (35%) clinic questionnaires were collected. Most of the respondent dentists had some deficient knowledge on basic life support (BLS), their mean score was 3.5 out of a maximum of 5. Most (>60%) of the respondents thought they were competent in performing medical emergency procedures except giving intravenous injection. Moreover, most (>60%) of them held positive attitude towards having immediate availability of essential medical emergency equipment and drugs in their clinic. Dentists who were more recent graduates, those with postgraduate qualifications, and those who work with accompaniment generally had higher mean BLS knowledge scores. In the dental clinics, the most commonly kept medical emergency equipment/drug was instant glucose (70%) and followed by antihistamine (62%). Only a quarter of the clinics were equipped with AED, and 45% were equipped with oxygen cylinder. For 8 out of the 11 items, a higher proportion of the bigger clinics (>2 dental chairs) than the smaller clinics had the medical emergency equipment/drug available (Chi-square test, p<0.05). Conclusion: Hong Kong dentists have a moderate level of knowledge on BLS which should be enhanced through regular attendance at CE courses. Their knowledge level is affected by a number of their background and professional activities factors. Most dental clinics in Hong Kong have only few of the essential medical emergency equipment and drugs while the larger clinics are better equipped than the smaller clinics.published_or_final_versio

Search for a light Higgs boson with the BABAR detector : with proposals to improve drift chamber aging studies and particle identification

In the Standard Model of particle physics, the Higgs boson is an elementary particle required to explain the origin of mass. One extension, the next-to-minimal supersymmetric Standard Model, predicts the existence of a GeV/c² scale Higgs boson, denoted A^0. This can be produced at B meson factories such as the BABAR experiment at the Stanford Linear Accelerator Center. We study e⁺e- → Υ(2S)→ π⁺π-Y(1S), Y(1S)→ γA^0, A^0 → gg, ss-bar, cc-bar decays using data collected by the BABAR detector at a centre-of-mass energy of 10.02 GeV/c². The search for A^0 → gg or ss-bar is performed by fully reconstructing the entire decay chain. We search for an excess of events relative to expected backgrounds in the reconstructed A^0 mass spectra. No significant excess is found. We set upper limits on product branching fraction B(Y(1S) → γA^0)xB(A^0 → gg) from 1x10-⁶ to 2x10-² for A^0 masses from 0.50 to 9.00 GeV/c², and B(Y(1S) → γA^0)x B(A^0 → ss-bar) from 5x10-⁶ to 1x10-³ for A^0 masses from 1.50 to 9.00 GeV/c². The search for A^0 → cc-bar is done by reconstructing the dipion transition, the radiative photon, and a D meson as a tag for cc-bar decays. We infer the mass of an A^0 candidate from the recoil of the dipion transition and the radiative photon. No significant signal is seen in the data and we set upper limits on product branching fraction B(Y(1S) → γA^0)xB(A^0 → cc-bar) from 7x10-⁵ to 2x10-³ for A^0 masses from 4.00 to 8.95 GeV/c² and 9.10 to 9.25 GeV/c². These are the first measurements to date and set constraints on the next-to-minimal supersymmetric Standard Model. Proposals to improve drift chamber aging studies and particle identification are included as part of the thesis. We propose to improve aging studies with prototypes that better resemble a full-scale drift chamber. Using TRIUMF beam data, we establish that at a particle identification efficiency of 95%, misidentification rates may be reduced from 2.2% to 1.9% by including likelihood tests and Kolmogorov-Smirnov tests and to 0.5% by including cluster counting.Science, Faculty ofPhysics and Astronomy, Department ofGraduat

Measurement of Upsilon (1S) Production at BaBar

BABAR is a particle physics experiment at the Stanford Linear Accelerator Center (SLAC). The purpose of BABAR is to study matter-antimatter asymmetry in the bottom quark system. At SLAC, electons and positrons collide, which annihilate and decay into a variety of daughters. An Upsilon(4S) meson is one of the possible daughters. An Upsilon(4S) decays into a B meson and an anti-B meson more than 96% of the time. A B meson has an anti-bottom quark and an anti-B meson has a bottom quark. The purpose of this thesis is to measure how many Upsilon(1S) originated from Upsilon(4S) in the entire BABAR data set. This thesis compares on-peak data and off-peak data. On-peak data was taken at center of mass energy 10.58GeV. One of the possible interactions is e+e− -> Upsilon(4S) since the mass of Upsilon(4S) is 10.58GeV/c^2. On-peak data, taken at center of mass energy 10.54GeV, is not enough to have any BB pairs because 10.54GeV is less than the mass of an Upsilon(4S). This thesis can be useful for BABAR physicist because it helps set an upper limit on how many BB pairs there are in the entire BABAR data set. In other words, it sets an upper limit on how much more than 96% does Upsilon(4S) decay to BB. Measurement of the decay of Upsilon(4S) -> Upsilon(1S) + X give evidence for non-BB decays of the Upsilon(4S). The final results of this study show that there were (110 +- 3) × 10^5 Upsilon(1S) on-peak, of which (10 +- 9) × 10^5 originated from an Upsilon(4S). Increasing the centre of mass energy from 10.54GeV to 10.58GeV increases the Upsilon(1S) production by (10 +- 8)%.Science, Faculty ofPhysics and Astronomy, Department ofUnreviewedUndergraduat

Device Sizing Guided by Echocardiography-Based Three-Dimensional Printing Is Associated with Superior Outcome after Percutaneous Left Atrial Appendage Occlusion

BACKGROUND: Left atrial appendage (LAA) occlusion is an alternative to anticoagulation for stroke prevention in patients with atrial fibrillation. Accurate device sizing is crucial for optimal outcome. Patient-specific LAA models can be created using three-dimensional (3D) printing from 3D transesophageal echocardiographic (TEE) images, allowing in vitro model testing for device selection. The aims of this study were to assess the association of model-based device selection with procedural safety and efficacy and to determine if preprocedural model testing leads to superior outcomes. METHODS: In 72 patients who underwent imaging-guided LAA occlusion, 3D models of the LAA were created from 3D TEE data sets retrospectively (retrospective cohort). The optimal device determined by in vitro model testing was compared with the actual device used. Associations of model-match and model-mismatch device sizing with outcomes were analyzed. In another 32 patients, device selection was prospectively guided by 3D models in adjunct to imaging (prospective cohort). The impact of model-based sizing on outcomes was assessed by comparing the two cohorts. RESULTS: Patients in the retrospective cohort with model-mismatch sizing had longer procedure times, more implantation failures, more devices used per procedure, more procedural complications, more peridevice leak, more device thrombus, and higher cumulative incidence rates of ischemic stroke and cardiovascular or unexplained death (P \u3c .05 for all) over 3.0 ± 2.3 years after LAA occlusion. Compared with the retrospective imaging-guided cohort, the prospective model-guided patients achieved higher implantation success and shorter procedural times (P \u3c .05) without complications. Clinical device compression (r = 0.92) and protrusion (r = 0.95) agreed highly with model testing (P \u3c .0001). Predictors for sizing mismatch were nonwindsock morphology (odds ratio, 4.7) and prominent LAA trabeculations (odds ratio, 7.1). CONCLUSIONS: In patients undergoing LAA occlusion, device size selection in agreement with 3D-printed model-based sizing is associated with improved safety and efficacy. Preprocedural device sizing with 3D models in adjunct to imaging guidance may lead to superior outcomes