177 research outputs found

    Entanglement Dynamics in Anti-PT\mathcal{PT}-Symmetric Systems

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    In the past years, many efforts have been made to study various noteworthy phenomena in both parity-time (PT\mathcal{PT}) and anti-parity-time (APT\mathcal{APT}) symmetric systems. However, entanglement dynamics in APT\mathcal{APT}-symmetric systems has not previously been investigated in both theory and experiments. Here, we investigate the entanglement evolution of two qubits in an APT\mathcal{APT}-symmetric system. In the APT\mathcal{APT}-symmetric unbroken regime, our theoretical simulations demonstrate the periodic oscillations of entanglement when each qubit evolves identically, while the nonperiodic oscillations of entanglement when each qubit evolves differently. In particular, when each qubit evolves near the exceptional point in the APT\mathcal{APT}-symmetric unbroken regime, there exist entanglement sudden vanishing and revival. Moreover, our simulations demonstrate rapid decay and delayed death of entanglement provided one qubit evolves in the APT\mathcal{APT}-symmetric broken regime. In this work, we also perform an experiment with a linear optical setup. The experimental results agree well with our theoretical simulation results. Our findings reveal novel phenomena of entanglement evolution in the APT\mathcal{APT}-symmetric system and opens a new direction for future studies on the dynamics of quantum entanglement in multiqubit APT\mathcal{APT}-symmetric systems or other non-Hermitian quantum systems.Comment: 13 pages, 8 figure

    Epidemiology and risk factors for Carbapenemase-Producing Enterobacteriaceae carriage in the hospital: a population-based nested case-control study

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    Objective: This study aims to study the epidemiology of Carbapenemase-producing Enterobacteriaceae (CPE) in Hong Kong. / Methods: This is a longitudinal population-based study reporting monthly CPE incidence rate and a nested case-control study for identifying risk factors for CPE carriage. The cases were patients with at least one CPE positive genotypic test, while the controls were randomly selected from the cohort with negative tests. Up to four controls per case were matched by sex, age group, and admission year-month. The independent risk factors were identified from a conditional logistic regression with potential covariates. / Results: From 1st January 2008 to 31st December 2019, 8,588 patients received CPE genotyping tests, and 2,353 had at least one positive result. Class B carbapenemase was the predominant enzyme in the samples (78.6%). The incidence rate increased from 0.04 in 2015 to 1.62 in 2019 per 10,000 person-year. In the nested case-control study, 1709 cases and 6664 controls were matched. Previous use of any beta-lactam antibiotics [Odds ratio:1.37 (1.22-1.53), p<.001] was found as an independent risk factor for carriage of CPE. / Conclusion: The carriage of CPE was found with an increasing trend in Hong Kong. Previous use of any beta-lactam antibiotics is a risk factor for CPE. / Summary: The incidence rate of Carbapenemase-producing Enterobacteriaceae is increasing in Hong Kong, with the predominant enzyme of class B carbapenemase. With multivariable conditional logistic regression, the previous use of any beta-lactam antibiotics was found as an independent risk factor for CPE carriage

    Chelation-driven fluorescence deactivation in three alkali earth metal MOFs containing 2,2’-dihydroxybiphenyl-4,4’-dicarboxylate

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    First published online 04 Sep 2013Three new metal-organic frameworks (MOFs) have been synthesised from alkali earth metal ions of increasing ionic radii (Mg, Ca and Sr) and 2,2’-dihydroxybiphenyl-4,4’-dicarboxylic acid (H4diol). The distinct coordination environments, framework topologies and the non-coordinated diol moieties accessed are a result of using differently sized metal ions for MOF synthesis which affects the ability of the diol moieties to chelate the metal. Detailed structural analysis of [Sr3(H2diol)3(DMF)5], [Ca3.5(Hdiol)(H2diol)2(DMF)5] and [Mg(H2diol)(DMF)2] show distinctive variations in variable temperature expansion/contraction properties and porosity. In addition, [Sr3(H2diol)3(DMF)5] and [Ca3.5(Hdiol)(H2diol)2(DMF)5] display a broad fluorescence emission (λmax = ~435 nm) under ultraviolet light due to the presence of non-coordinated biphenyl-diol moieties within the structures, while chelation of Mg by the diol pocket in [Mg(H2diol)(DMF)2] leads to quenching of the ligand fluorescence.Damien Rankine, Tony D. Keene, Christopher J. Sumby and Christian J. Doona

    Clinical and Epidemiologic Research Ethnic Variation in Early Age-Related Macular Degeneration Lesions Between White Australians and Singaporean Asians

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    Citation: Joachim N, Mitchell P, Younan C, et al. Ethnic variation in early age-related macular degeneration lesions between white Australians and Singaporean Asians. Invest Ophthalmol Vis Sci. 2014;55:4421-4429. DOI:10.1167/iovs.14-14476 PURPOSE. We compared early age-related macular degeneration (AMD) lesion characteristics between white Australians and Singaporean Asians. METHODS. Participants of the Blue Mountains Eye Study (BMES; whites, n ¼ 3508) and the Singapore Epidemiology of Eye Disease Study (SEED; Malay, n ¼ 3280, Indian, n ¼ 3400, and Chinese, n ¼ 3353) underwent examinations, including retinal photography. The AMD lesions were assessed following the Wisconsin AMD grading protocol by the same photographic grader. Prevalence and characteristics of early AMD lesions were compared between the BMES and the SEED. The associations between ethnicity and early AMD lesion types were analyzed using logistic regression models adjusting for age, sex, smoking status, lipids, and genetic polymorphisms associated with AMD. RESULTS. After age-standardization to the BMES population, the prevalence of distinct soft drusen was significantly higher in Singaporeans compared to Australians (23.9%, 95% confidence interval [CI] 22.9-25.0 vs. 6.2%, 95% CI 5.3-7.0), with an adjusted odds ratio (OR) of 4.6 (95% CI 3.4-6.0). In contrast, the prevalence of indistinct soft or reticular drusen was significantly lower in Singaporeans compared to Australians (6.5%, 95% CI 5.9-7.1 vs. 8.3%, 95% CI 7.4-9.3, with nonsignificant adjusted OR of 1.2, 95% CI 0.8-1.7). Soft drusen of any type were present frequently at the inner and outer macula (within a zone ‡500 to &lt;3000 lm radius from the foveal center) among Singaporeans, while among Australians soft drusen were present more frequently at the central macula (&lt;500 lm radius). CONCLUSIONS. Singaporean Asians had a milder spectrum of early AMD lesions and lesion characteristics (predominantly distinct soft drusen and noncentral location) compared to white Australians

    Risk of thyroid dysfunction associated with mRNA and inactivated COVID-19 vaccines: a population-based study of 2.3 million vaccine recipients

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    Background: In view of accumulating case reports of thyroid dysfunction following COVID-19 vaccination, we evaluated the risks of incident thyroid dysfunction following inactivated (CoronaVac) and mRNA (BNT162b2) COVID-19 vaccines using a population-based dataset. / Methods: We identified people who received COVID-19 vaccination between 23 February and 30 September 2021 from a population-based electronic health database in Hong Kong, linked to vaccination records. Thyroid dysfunction encompassed anti-thyroid drug (ATD)/levothyroxine (LT4) initiation, biochemical picture of hyperthyroidism/hypothyroidism, incident Graves’ disease (GD), and thyroiditis. A self-controlled case series design was used to estimate the incidence rate ratio (IRR) of thyroid dysfunction in a 56-day post-vaccination period compared to the baseline period (non-exposure period) using conditional Poisson regression. / Results: A total of 2,288,239 people received at least one dose of COVID-19 vaccination (57.8% BNT162b2 recipients and 42.2% CoronaVac recipients). 94.3% of BNT162b2 recipients and 92.2% of CoronaVac recipients received the second dose. Following the first dose of COVID-19 vaccination, there was no increase in the risks of ATD initiation (BNT162b2: IRR 0.864, 95% CI 0.670–1.114; CoronaVac: IRR 0.707, 95% CI 0.549–0.912), LT4 initiation (BNT162b2: IRR 0.911, 95% CI 0.716–1.159; CoronaVac: IRR 0.778, 95% CI 0.618–0.981), biochemical picture of hyperthyroidism (BNT162b2: IRR 0.872, 95% CI 0.744–1.023; CoronaVac: IRR 0.830, 95% CI 0.713–0.967) or hypothyroidism (BNT162b2: IRR 1.002, 95% CI 0.838–1.199; CoronaVac: IRR 0.963, 95% CI 0.807–1.149), GD, and thyroiditis. Similarly, following the second dose of COVID-19 vaccination, there was no increase in the risks of ATD initiation (BNT162b2: IRR 0.972, 95% CI 0.770–1.227; CoronaVac: IRR 0.879, 95%CI 0.693–1.116), LT4 initiation (BNT162b2: IRR 1.019, 95% CI 0.833–1.246; CoronaVac: IRR 0.768, 95% CI 0.613–0.962), hyperthyroidism (BNT162b2: IRR 1.039, 95% CI 0.899–1.201; CoronaVac: IRR 0.911, 95% CI 0.786–1.055), hypothyroidism (BNT162b2: IRR 0.935, 95% CI 0.794–1.102; CoronaVac: IRR 0.945, 95% CI 0.799–1.119), GD, and thyroiditis. Age- and sex-specific subgroup and sensitivity analyses showed consistent neutral associations between thyroid dysfunction and both types of COVID-19 vaccines. / Conclusions: Our population-based study showed no evidence of vaccine-related increase in incident hyperthyroidism or hypothyroidism with both BNT162b2 and CoronaVac
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