36 research outputs found

    Spin-driven stationary turbulence in spinor Bose-Einstein condensates

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    We report the observation of stationary turbulence in antiferromagnetic spin-1 Bose-Einstein condensates driven by a radio-frequency magnetic field. The magnetic driving injects energy into the system by spin rotation and the energy is dissipated via dynamic instability, resulting in the emergence of an irregular spin texture in the condensate. Under continuous driving, the spinor condensate evolves into a nonequilibrium steady state with characteristic spin turbulence, while the low energy scale of spin excitations ensures that the sample's lifetime is minimally affected. When the driving strength is on par with the system's spin interaction energy and the quadratic Zeeman energy, remarkably, the stationary turbulent state exhibits spin-isotropic features in spin composition and spatial spin texture. We numerically show that ambient field fluctuations play a crucial role in sustaining the turbulent state within the system. These results open up new avenues for exploring quantum turbulence in spinor superfluid systems.Comment: 9 pages, 9 figure

    Factors for progressive pulmonary fibrosis in connective tissue disease-related interstitial lung disease

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    Background: Progressive fibrosis can occur in connective tissue disease (CTD)-related interstitial lung disease (ILD) and make the prognosis worse. Objectives: This study aimed to investigate factors related to progressive pulmonary fibrosis (PPF) phenotype in CTD-ILDs. Design: Medical records of patients diagnosed as CTD and ILD at a single, tertiary hospital in South Korea were retrospectively reviewed. Methods: Patients whose lung functions were followed up for more than a year were included in analysis. PPF was defined as forced vital capacity (FVC) declined ⩾10% or diffusion capacity of carbon monoxide (DLco) ⩾15%. Results: Of 110 patients with CTD-ILD, 24.5% progressed into PPF. Rheumatoid arthritis (RA) and Sjogren’s disease accounted for more than 63% of PPF. Compositions of CTD type were similar between PPF and non-PPF. Clinical characteristics and proportion of usual interstitial pneumonia (UIP) pattern on chest images were also similar between PPF and non-PPF. Approximately 10% of patients in both groups were treated with anti-fibrotic agents. Use of systemic steroids and/or other immunomodulating agents lowered the risk of developing PPF in CTD-ILD patients after adjusting for gender-age-physiology score and smoking status (adjusted odds ratio: 0.25, 95% confidence interval: 0.07–0.85). Conclusion: About a quarter of CTD-ILD progressed into PPF. The use of immunomodulating agents lowered the risk of developing PPF. To improve outcomes of patients, future studies need to detect patients at higher risk for PPF earlier and set up clinical guidelines for treatment strategies in the process of PPF

    Performance Evaluation of Waterproofing Membrane Systems Subject to the Concrete Joint Load Behavior of Below-Grade Concrete Structures

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    Below-grade structures such as parking lots, underground subway tunnels, and basements are growing in scale and reaching deeper below-ground levels. In this type of environment, they become subject to higher water pressure. The concrete material of the structures is exposed to wet conditions for longer periods of time, which makes the proper adhesion of waterproofing membranes difficult. Joint movements from increased structural settlement, thermal expansion/shrinkage, and physical loads from external sources (e.g., vehicles) make securing durable waterproofing challenging. While ASTM Guides, Korean Codes, and BS Practice Codes on below-grade waterproofing stress the importance of manufacturer specification for quality control, ensuring high quality waterproofing for the ever-changing scale of construction remains a challenge. This study proposes a new evaluation method and criteria which allow for the selection of waterproofing membranes based on specific performance attributes and workmanship. It subjects six different waterproofing membrane systems (installed on dry and wet surface conditioned mortar slab specimens with an artificial joint to different cyclic movement widths) to 300 cycles in water to demonstrate that inadequate material properties and workmanship are key causes for leakages

    Arc Stability Index Using Phase Electrical Power in AC Electric Arc Furnace

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    Critical Energy Dissipation in a Binary Superfluid Gas by a Moving Magnetic Obstacle

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    © 2021 American Physical Society.We study the critical energy dissipation in an atomic superfluid gas with two symmetric spin components by an oscillating magnetic obstacle. Above a certain critical oscillation frequency, spin-wave excitations are generated by the magnetic obstacle, demonstrating the spin superfluid behavior of the system. When the obstacle is strong enough to cause density perturbations via local saturation of spin polarization, half-quantum vortices (HQVs) are created for higher oscillation frequencies, which reveals the characteristic evolution of critical dissipative dynamics from spin-wave emission to HQV shedding. Critical HQV shedding is further investigated using a pulsed linear motion of the obstacle, and we identify two critical velocities to create HQVs with different core magnetization.11Nsciescopu

    Association between Obesity and Carotid Intima-Media Thickness in Korean Office Workers: The Mediating Effect of Physical Activity

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    Background. Obesity and physical inactivity are associated with higher prevalence of cardiovascular disease (CVD). Objective. This study investigated the association between obesity and carotid intima-media thickness (CIMT) stratified by physical activity (PA) in Korean office workers. Methods. Data obtained from 914 office workers aged 21-60 years (347 women) were used. Resting blood pressures, body mass index (BMI), and waist-to-height ratio (WHtR) were measured. PA was assessed using the international physical activity questionnaire. CIMT was assessed with a carotid artery ultrasonography. Logistic regression analysis was used to estimate the odds ratio (OR) and 95% confidence interval (CI) of obesity stratified by weekly PA for an abnormally increased CIMT. Results. Logistic regression analyses showed that those who were overall obese (OR=2.50, 95% CI=1.60-3.91, P<0.001) or central obese (OR=2.08, 95% CI=1.29-3.40, P=0.003) had significantly higher estimated risks of having an abnormally increased CIMT even after adjustments for age, sex, smoking, alcohol consumption, resting blood pressures, and history of hypertension, diabetes, and hyperlipidemia, as compared with those who were not overall or central obese (OR=1). A multivariate linear regression suggested that age (P<0.001), sex (P=0.002), hypertension (P=0.014), smoking (P=0.054), BMI (P<0.001), and physical activity (P=0.011) were important determinants of abnormally elevated CIMT in this study population. Conclusion. The current findings suggest that the risk of obesity for an abnormally increased CIMT is significantly modulated by demographics as well as lifestyle-related risk factors including smoking and physical inactivity in Korean office workers

    A comparative study on field, temperature, and strain dependences of the critical current for doped and undoped MgB2 wires based on the percolation model

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    Field, temperature, and strain dependences of the critical current for a SiC doped multifilamentary in situ MgB2 wire have been studied. Measurement results were compared with that of the undoped wire, and the origin of the difference in the critical current is discussed. The critical current can be calculated with the percolation model considering the effect of anisotropy. The temperature dependence of the fitting parameters, the upper critical field along the ab-plane, and c-axis is compared with the dirty-limit two-gap theory. To assess the validity of the fitting parameters, resistive transition has been measured especially to extract the upper critical field directly. It is shown that even the resistive broadening can be well explained by a simple parallel path model using the fitting parameters obtained from the critical current analysis

    Vision-based surface defect inspection for thick steel plates

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    There are several types of steel products, such as wire rods, cold-rolled coils, hot-rolled coils, thick plates, and electrical sheets. Surface stains on cold-rolled coils are considered defects. However, surface stains on thick plates are not considered defects. A conventional optical structure is composed of a camera and lighting module. A defect inspection system that uses a dual lighting structure to distinguish uneven defects and color changes by surface noise is proposed. In addition, an image processing algorithm that can be used to detect defects is presented in this paper. The algorithm consists of a Gabor filter that detects the switching pattern and employs the binarization method to extract the shape of the defect. The optics module and detection algorithm optimized using a simulator were installed at a real plant, and the experimental results conducted on thick steel plate images obtained from the steel production line show the effectiveness of the proposed method. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)111sciescopu

    Al2O3-Coated Si-Alloy Prepared by Atomic Layer Deposition as Anodes for Lithium-Ion Batteries

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    Silicon-based anodes can increase the energy density of Li-ion batteries (LIBs) owing to their large weights and volumetric capacities. However, repeated charging and discharging can rapidly deteriorate the electrochemical properties because of a large volume change in the electrode. In this study, a commercial Fe-Si powder was coated with Al2O3 layers of different thicknesses via atomic layer deposition (ALD) to prevent the volume expansion of Si and suppress the formation of crack-induced solid electrolyte interfaces. The Al2O3 content was controlled by adjusting the trimethyl aluminum exposure time, and higher Al2O3 contents significantly improved the electrochemical properties. In 300 cycles, the capacity retention rate of a pouch full-cell containing the fabricated anodes increased from 69.8% to 72.3% and 79.1% depending on the Al2O3 content. The powder characterization and coin and pouch cell cycle evaluation results confirmed the formation of an Al2O3 layer on the powder surface. Furthermore, the expansion rate observed during the charging/discharging of the pouch cell indicated that the deposited layer suppressed the powder expansion and improved the cell stability. Thus, the performance of an LIB containing Si-alloy anodes can be improved by coating an ALD-synthesized protective Al2O3 layer
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