589 research outputs found

    Two-parameter estimation with three-mode NOON state in a symmetric three-well

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    We propose a theoretical scheme to realize two-parameter estimation via a Bose-Einstein condensates confined in a symmetric triple-well. The three-mode NOON state is prepared adiabatically as the initial state. Two phase differences between the wells are two parameters to be estimated. With the help of classical and quantum Fisher information, we study the sensitivity of the triple-well on estimating two phase parameters simultaneously. The result shows that the precision of simultaneous estimation of two parameters in a triple-well system can reach the Heisenberg scaling

    A Fast Method to Measure the Volume of a Large Cavity

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    How to quickly and accurately measure the volume of a large cavity is challenging. This paper presents an efficient method to measure the volume of a large conducting cavity. The proposed method is based on statistical wave theory. By measuring the Q factor in the time and frequency domains, the volume of the cavity can be extracted. In the time domain, the Q factor can be extracted directly from the time domain response, while in the frequency domain, the Q factor depends on the volume of the cavity and the transferred power; the transferred power can be measured directly. By correcting the frequency domain Q with the radiation efficiency of antennas, the Q factors obtained from both the time and frequency domains are equal in a well-stirred chamber; this provides an opportunity to measure the volume of the cavity. Measurements are conducted to verify the proposed method. Although the measurement is conducted using electromagnetic waves, acoustic waves can also be used; in this case, the approach can be applied to any cavity, not limited to a conducting cavity. The advantages and the limitations of the proposed method are also discussed

    Verum- versus Sham-Acupuncture on Alzheimer’s Disease (AD) in Animal Models: A Preclinical Systematic Review and Meta-Analysis

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    Background. Alzheimer’s disease (AD) is a common health condition affecting senile people and leads to severe cognitive dysfunctions. Acupuncture has been shown to be a possible alternative natural remedy for AD in some animal studies. Objective. To perform a systematic review to identify the effect of verum-acupuncture compared with sham-acupuncture on learning and memory performance among animal models of AD. Methods. Experimental animal studies of treating AD via verum- and sham- acupuncture were searched in nine electronic databases, including Sciverse ScienceDirect, PubMed, Springer, Ebsco Medline, AMED, EMBASE (Elsevier), Scopus (Elsevier), PsycINFO (ProQuest), and OVID from the dates of the databases’ inception to June 2019. The Morris water maze test was considered as an outcome measure. The software Revman 5.3 and Stata 16.0 were used to conduct the meta-analysis. Heterogeneity was examined by using I2 statistics. The publication bias was assessed via Begg’s test by Stata 16.0. Results. Twelve studies involving 229 animals met the inclusion criteria. Most of the studies had a moderate quality according to SYRCLE's risk of bias tool for animal studies. The results of the meta-analysis indicated that verum-acupuncture could reduce the escape latency (MD = −12.90, 95% CI (−17.08, −8.71), ) and increase the time spent in the original platform quadrant (MD = 7.28, 95% CI (4.23, 10.33), ) and frequency of the crossing former platform (MD = 2.01, 95% CI (1.53, 2.50), ) compared with the sham-acupuncture. Conclusions. Acupuncture is effective in improving cognitive functions in AD animal models, and this benefit is more than just a placebo effect. Further clinical trials are needed to confirm the findings.This work was sponsored by the Teaching and Research Award Program for Outstanding Young Teachers, Shanghai Sanda University (No. 2018zz13) and Special Project for Clinical Research, Shanghai Municipal Health Commission (No. 20174Y0009). The publication of this article was funded by the Qatar National Library. The authors would like to extend their gratitude to Yuen-Shan Ho, from School of Nursing, The Hong Kong Polytechnic University, for inspiring them to seek the underlying research directions. Besides, the authors thank Hai-Dong Guo, from School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, for providing help in organizing the data and Yan Xu, the chair of Nursing Department, Shanghai Sanda University, for providing general support

    Numerical study on aerodynamic characteristics of high-speed trains with considering thermal-flow coupling effects

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    In order to conduct in-depth researches on rationality of air conditioning system equipment of a high-speed train as well as its pipeline system design, working conditions of the air conditioning system and distribution of aerodynamic characteristics including pressure, velocity and temperature in high speed trains should be computed carefully at the design stage. Therefore, the finite volume method was used to solve a governing equation of computational fluid dynamics. The aerodynamic characteristics of pipelines of the air conditioning system and the complete high speed train were computed, so the indoor distribution of wind velocity, temperature and gas concentration (carbon oxide, carbon dioxide, nitrogen and so forth) was obtained. The flow field index and the thermal comfort index were used to evaluate the indoor thermal comfort degree. In this way, whether rationality of the air conditioning system design and indoor aerodynamic characteristic could satisfy requirements for design specifications can be analyzed. Results show that: Under winter or summer working conditions, wind velocity was relatively high at the passageway door, where the maximum wind velocity was more than 1 m/s and would make passengers uncomfortable. Air flow velocity outside comfortable regions was more than 0.05 m/s, satisfying UIC553 standards. Velocity distribution was basically the same indoors, where wind velocity was large at positions perpendicular to the air supply hole, and the maximum wind velocity was more than 1 m/s, but wind velocity was uniform in the passenger region, which was basically lower than 0.2 m/s and satisfied UIC553 standards. In summer and winter working conditions, distribution of pressure, velocity and temperature was not uniform, where the maximum temperature gradient was near the air inlet in the compartment. Air components in the compartment satisfied requirements for comfort. The most uncomfortable regions in the compartment were concentrated at the passageway. Air supply holes distributed symmetrically on the train roof caused high air flow intensity, high wind velocity, low temperature and high humidity at the passageway in the compartment, so the thermal comfort was low, and it is feasible to adjust the layout of air supply holes appropriately

    High remission and low relapse with prolonged intensive DMARD therapy in rheumatoid arthritis (PRINT): A multicenter randomized clinical trial

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    Objectives: To determine whether prolonged intensive disease-modifying antirheumatic drug (DMARD) treatment (PRINT) leads to high remission and low relapse rates in patients with severe rheumatoid arthritis (RA). Methods: In this multicenter, randomized and parallel treatment trial, 346 patients with active RA (disease activity score (28 joints) [DAS28] (erythrocyte sedimentation rate [ESR]) > 5.1) were enrolled from 9 centers. In phase 1, patients received intensive treatment with methotrexate, leflunomide, and hydroxychloroquine, up to 36 weeks, until remission (DAS28 ≤ 2.6) or a low disease activity (2.6 < DAS28 ≤ 3.2) was achieved. In phase 2, patients achieving remission or low disease activity were followed up with randomization to 1 of 2 step-down protocols: leflunomide plus hydroxychloroquine combination or leflunomide monotherapy. The primary endpoints were good European League Against Rheumatism (EULAR) response (DAS28 (ESR) < 3.2 and a decrease of DAS28 by at least 1.2) during the intensive treatment and the disease state retention rate during step-down maintenance treatment. Predictors of a good EULAR response in the intensive treatment period and disease flare in the maintenance period were sought. Results: A good EULAR response was achieved in 18.7%, 36.9%, and 54.1% of patients at 12, 24, and 36 weeks, respectively. By 36 weeks, 75.4% of patients achieved good and moderate EULAR responses. Compared with those achieving low disease activity and a high health assessment questionnaire (HAQ > 0.5), patients achieving remission (DAS28 ≤ 2.6) and low HAQ (≤ 0.5) had a significantly higher retention rate when tapering the DMARDs treatment (P = 0.046 and P = 0.01, respectively). There was no advantage on tapering to combination rather than monotherapy. Conclusions: Remission was achieved in a proportion of patients with RA receiving prolonged intensive DMARD therapy. Low disease activity at the start of disease taper leads to less subsequent flares. Leflunomide is a good maintenance treatment as single treatment

    Early Triassic microbialites from the Changxing Region of Zhejiang Province, South China

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    © 2019, The Author(s). Microbialites, often considered as a signal of extreme marine environment, are common in the Lower Triassic strata of South China where they flourished in the aftermath of the end-Permian mass extinction. Early Triassic microbialite facies are known to vary palaeogeographically, perhaps due to differing climates, ocean chemistry, and water depths. This paper provides the first record of a brief, but spectacular development of microbialites in the aftermath of the end-Permian mass extinction at Panjiazhuang section, Changxing Region of Zhejiang Province (eastern South China). Here, the Upper Permian Changxing Formation comprises typical shallow platform facies rich in calcareous algae and foraminifera, the development of which was terminated by the major end-Permian regression. A 3.4-m-thick microbialite began to form at the onset of the transgression in the earliest Triassic. The microbialite at Panjiazhuang section is composed of thrombolite that contains abundant calcified cyanobacteria, small gastropods, microconchid tubes and ostracods, representing a low-diversity shallow marine community in the aftermath of the end-Permian crisis. The microbialites are succeeded by thin-bedded micrites bearing thin-shelled bivalves, which record a rapid sea-level rise in the Early Triassic. Abundant populations of small pyrite framboids are observed in the upper part of the microbialites and the overlying thin-bedded micrites, suggesting that dysoxic water conditions developed at that time. The appearance of microbialites near the Permian–Triassic boundary (PTB) at Panjiazhuang section was the result of peculiar marine conditions following the end-Permian regression, whilst their disappearance was due to the increasing water depth and the development of dysoxia

    Seroprevalence of Toxoplasma gondii infection in pet dogs in Kunming, Southwest China

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    BACKGROUND: Toxoplasmosis is a zoonotic parasitic disease caused by the protozoan Toxoplasma gondii, which infects almost all warm-blooded animals, including humans, with a worldwide distribution. However, little is known of T. gondii seroprevalence in pet dogs in Kunming, the capital of Yunnan Province, southwest China. The objective of this investigation was to estimate the seroprevalence of T. gondii infection in pet dogs in this area. METHODS: A total of 611 serum samples were collected from 7 pet hospitals in Kunming, and assayed for T. gondii antibodies by the indirect haemagglutination (IHA) using a commercially-marked kit. RESULTS: 132 (21.6%) pet dogs were positive for T. gondii antibodies, and the seroprevalence ranged from 17.3% to 34.7% among different sampling regions, the difference was statistically significant (P < 0.05). The T. gondii seroprevalence in female and male dogs were 20.8% and 22.4%, respectively, the difference was not statistically significant (P > 0.05). The seroprevalence ranged from 17.5% to 23.6% among different age groups, but the difference was not statistically significant (P > 0.05), and there were no interactions in statistics (P > 0.05) between gender and age of pet dogs in the region. CONCLUSIONS: The findings of the present survey indicate high T. gondii seroprevalance in pet dogs in Kunming, southwest China, posing significant public health concern. It is necessary to enhance integrated strategies and measures to prevent and control T. gondii infection in pet dogs in this area

    Even-Odd Layer-Dependent Anomalous Hall Effect in Topological Magnet MnBi2Te4 Thin Films

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    A central theme in condensed matter physics is to create and understand the exotic states of matter by incorporating magnetism into topological materials. One prime example is the quantum anomalous Hall (QAH) state. Recently, MnBi2Te4 has been demonstrated to be an intrinsic magnetic topological insulator and the QAH effect was observed in exfoliated MnBi2Te4 flakes. Here, we used molecular beam epitaxy (MBE) to grow MnBi2Te4 films with thickness down to 1 septuple layer (SL) and performed thickness-dependent transport measurements. We observed a non-square hysteresis loop in the antiferromagnetic state for films with thickness greater than 2 SL. The hysteresis loop can be separated into two AH components. Through careful analysis, we demonstrated that one AH component with the larger coercive field is from the dominant MnBi2Te4 phase, while the other AH component with the smaller coercive field is from the minor Mn-doped Bi2Te3 phase in the samples. The extracted AH component of the MnBi2Te4 phase shows a clear even-odd layer-dependent behavior, a signature of antiferromagnetic thin films. Our studies reveal insights on how to optimize the MBE growth conditions to improve the quality of MnBi2Te4 films, in which the QAH and other exotic states are predicted.Comment: 23 pages, 4 figures, comments are welcom
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