1,611 research outputs found
Enhancement of quantum nondemolition measurements with an electro-optic feed-forward amplifier
Methods for the enhancement of optical quantum nondemolition (QND) measurements are discussed. We review the use of meter squeezing; as a QND enhancement tool and present a method of QND enhancement using an electro-optic feed-forward amplifier. By applying a linearized theory it is shown that these techniques work very well together. The combined effect of these enhancement methods is modeled for two QND systems, a squeezed light beam splitter and an optical parametric amplifier. We also discuss the conflict between the normal QND criteria and QND systems that involve noiseless amplification. We use an additional parameter to quantify the problem. A method for correcting the effects of noiseless amplification is discussed and modeled. We also discuss a special case of QND that eliminates the optical interaction between the meter and signal input beams. This system is shown to be a very effective QND device. [S1050-2947(99)06411-2]
Noiseless electro-optic processing of optical signals generated with squeezed light
We demonstrate an elegant way of handling optical signals which are generated using squeezed states of light without losing their improved signal to noise ratio. We do this by amplifying, without significant noise penalty, both signal and noise away from the quantum noise limit into the classical domain. This makes the information robust to losses. Our system achieves a signal transfer coefficient, T-s, close to unity. As a demonstration we amplify a small signal carried by 35% amplitude squeezed light and show that unlike the fragile squeezed input, the signal amplified output is robust to propagation losses. A signal transfer coefficient of T-s = 0.75 is achieved even in the presence of large introduced (86%) downstream losses. (C) 1998 Optical Society of America
於香港一所大學醫院推行以畸變產物耳聲發射檢查為新生兒進行聽覺普查計劃之可行性
OBJECTIVE: To assess the feasibility of implementing a universal neonatal hearing screening programme using distortion product otoacoustic emission detection at a major teaching hospital in Hong Kong. DESIGN: Descriptive study and questionnaire. SETTING. Teaching hospital, Hong Kong. METHODS: A total of 1064 infants, together with their mothers, were successfully recruited for the study. The participation rate was 99.3%. A three-stage hearing screening protocol using distortion product otoacoustic emission detection was adopted. Each of the participating infants was screened on three separate occasions (day 1-4, day 5-14, and day 21-30 after birth), irrespective of the test results. A questionnaire was administered to 364 randomly selected mothers to determine whether as consumers of the hearing screening service, mothers would find screening desirable. RESULTS: Results of the screening demonstrated an incidence of permanent bilateral hearing loss (>or=40 dB in the better ear) of 0.28%. The results also showed that 3.5% of the screened infants were referred for subsequent diagnostic audiological assessment, including those suspected with unilateral as well as bilateral hearing loss. Data obtained were comparable to other reported results obtained using multi-stage screening protocols. Taking both the false positive rate and the default rate into consideration, the most appropriate time for screening in this hospital setting appeared to be around day 5 to 14 when infants returned to the hospital's day centre as out-patients for routine medical follow-up. Since this day centre service is not generally provided by all maternity hospitals in Hong Kong, an alternative time for screening would be around day 21 to 30 when infants could return as out-patients solely for the hearing test. The results of the questionnaire suggested that most mothers thought a neonatal hearing screening would be desirable (91.35%). The majority (81.70%) indicated a preference for screening either within a few days of birth at the maternity ward prior to discharge from the hospital, or between 5 and 30 days when returning to the hospital as an out-patient. CONCLUSION: It was concluded that a universal neonatal hearing screening programme could be readily implemented in a maternity hospital setting in Hong Kong.published_or_final_versio
HRCT quantification of bronchiectasis: a functional-morphologic study
published_or_final_versio
Case series of Jehovah's witnesses having Total Knee Arthroplasty in Hong Kong
Electronic Poster Presentations: P48INTRODUCTION: Total knee arthroplasty (TKA) is challenging in Jehovah’s Witnesses (JW), as they do not accept transfusions. We report our experiences with a series of TKAs in JW in our ...postprin
Motivating smokers at outdoor public smoking hotspots to have a quit attempt with a nicotine replacement therapy sample: study protocol for a randomized controlled trial
© 2016 Cheung et al.Background: About half of the daily smokers in Hong Kong have never tried and have no intention to quit smoking. More than one-third (37.9 %) of daily smokers have attempted to quit but failed. Nicotine replacement therapy (NRT) is a safe and effective pharmacotherapy to increase abstinence by reducing withdrawal symptoms during the early stage of smoking abstinence. However, the prevalence of NRT use in Hong Kong is lower than in most developed countries. The proposed study aims to assess the effectiveness of providing free NRT samples to smokers on increasing quit attempts and the quit rate. Methods: Trained university undergraduate students as ambassadors will invite smokers at outdoor public smoking hotspots to participate in the randomized controlled trial, in which eligible smokers will be randomized to receive a 1-week free NRT sample and medication counselling (intervention) or advice to purchase NRT on their own (control). The primary outcome is self-reported quit attempts (no smoking for at least 24 hours) in the past 30 days at 1-month and 3-month telephone follow-up. Discussion: The findings will inform the effectiveness of delivering free NRT samples at outdoor public smoking hotspots to increase quit attempts and abstinence. The study will also provide information on smokers' adherence to the NRT sample, side effects and safety issues related to the usage. This will improve the design of a large trial to test the effect of the NRT sample. Trial registration: ClinicalTrials.gov NCT02491086. Registered on 7 July 2015.published_or_final_versio
Quantum Communications with Compressed Decoherence Using Bright Squeezed Light
We propose a scheme for long-distance distribution of quantum entanglement in
which the entanglement between qubits at intermediate stations of the channel
is established by using bright light pulses in squeezed states coupled to the
qubits in cavities with a weak dispersive interaction. The fidelity of the
entanglement between qubits at the neighbor stations (10 km apart from each
other) obtained by postselection through the balanced homodyne detection of 7
dB squeezed pulses can reach F=0.99 without using entanglement purification, at
same time, the probability of successful generation of entanglement is 0.34.Comment: 4 pages, 2 figure
Hong Kong domestic health spending: financial years 1989/90 to 2005/06
This report presents the latest estimates of Hong Kong domestic health spending between fiscal years 1989/90 and 2005/06, cross-stratified and categorised by financing source, provider, and function on an annual basis. In fiscal year 2005/06, total health expenditure was HK71 557 million total health expenditure in 2005/06, HK2746 million (3.8%) on capital expenses (ie investment in medical facilities). Services of curative care accounted for the largest share (67.3%) and were made up of ambulatory services (35.7%), in-patient services (27.7%), day patient hospital services (3.4%), and home care (0.6%). The second largest share was spending on medical goods outside the patient care setting (10.8%). In terms of health care providers, hospitals (44.0%) accounted for the largest share of total health expenditure in 2005/06, followed by providers of ambulatory health care (31.4%). We observed a system-wide trend towards service consolidation at institutions (as opposed to free-standing ambulatory clinics, most of which are staffed by solo practitioners). Not taking capital expenses (ie investment in medical facilities) into account, public current expenditure on health amounted to HK33 961 million) was mostly incurred at providers of ambulatory health care (55.8%). This reflects the mixed health care economy of Hong Kong, where public hospitals generally account for about 90% of total bed-days and private doctors (including western and Chinese medicine practitioners) provide about 70% of out-patient care. Although both public and private spending were mostly expended on personal health care services and goods (93.0%), the patterns of distribution among functional categories differed. Public expenditure was targeted at in-patient care (53.7%) and substantially less on out-patient care (24.6%), especially low-intensity first-contact care. In comparison, private spending was concentrated on out-patient care (49.9%), followed by medical goods outside the patient care setting (22.0%) and in-patient care (19.0%). Compared to countries of the Organisation for Economic Co-operation and Development, Hong Kong has devoted a relatively low percentage of gross domestic product on health services in the last decade. As a share of total spending, public funding (either general government revenue or social security funds) was also lower than in most comparably developed economies, although commensurate with its public revenue collection base.published_or_final_versio
- …