976 research outputs found

    Temperature-dependent evolutions of excitonic superfluid plasma frequency in a srong excitonic insulator candidate, Ta2_2NiSe5_5

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    We investigate an interesting anisotropic van der Waals material, Ta2_{2}NiSe5_{5}, using optical spectroscopy. Ta2_{2}NiSe5_{5} has been known as one of the few excitonic insulators proposed over 50 years ago. Ta2_{2}NiSe5_{5} has quasi-one dimensional chains along the aa-axis. We have obtained anisotropic optical properties of a single crystal Ta2_{2}NiSe5_{5} along the aa- and cc-axes. The measured aa- and cc-axis optical conductivities exhibit large anisotropic electronic and phononic properties. With regard to the aa-axis optical conductivity, a sharp peak near 3050 cm1^{-1} at 9 K, with a well-defined optical gap (ΔEI\Delta^{EI} \simeq 1800 cm1^{-1}) and a strong temperature-dependence, is observed. With an increase in temperature, this peak broadens and the optical energy gap closes around \sim325 K(TcEIT_c^{EI}). The spectral weight redistribution with respect to the frequency and temperature indicates that the normalized optical energy gap (ΔEI(T)/ΔEI(0)\Delta^{EI}(T)/\Delta^{EI}(0)) is 1(T/TcEI)21-(T/T_c^{EI})^2. The temperature-dependent superfluid plasma frequency of the excitonic condensation in Ta2_{2}NiSe5_{5} has been determined from measured optical data. Our findings may be useful for future research on excitonic insulators.Comment: 17 pages, 5 figure

    Prevalence and Management of Diabetes in Korean Adults: Korea National Health and Nutrition Examination Surveys 1998–2005

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    OBJECTIVE: This research investigated recent changes in the prevalence and management status of diabetes among Korean adults. RESEARCH DESIGN AND METHODS: The Korea National Health and Nutrition Examination Survey (KNHANES), a nationwide survey examining the general health and nutrition status of the Korean people, was conducted in 1998, 2001, and 2005. Using the first (1998; n = 5,645), second (2001; n = 4,154), and third (2005; n = 4,628) KNHANES datasets, in the present study, we estimated the prevalence of diabetes among Korean adults (aged >or=30 years), the proportions of known cases of diabetes, and the proportions of well-controlled cases of diabetes, as defined by either the American Diabetes Association (A1C <7%) or the International Diabetes Federation guidelines (A1C <6.5%). RESULTS: In 2005, the prevalence of diabetes was estimated to be 9.1% (approximately 2.58 million people: 10.2% of men and 7.9% of women), including 6.2% with known diabetes and 2.9% with newly diagnosed diabetes. The prevalence of impaired fasting glucose was 17.4% (approximately 4.94 million people). The proportion of known cases of diabetes drastically increased from 23.2% in 1998 to 41.2% in 2001 and 68.0% in 2005 (P < 0.0001). Among known diabetic patients in 2005, 43.5 and 22.9% had A1C levels <7.0 and <6.5%, respectively. CONCLUSIONS: The overall prevalence of diabetes in Korea has not changed significantly between 1998 and 2005. Physician diagnosis and treatment rates of diabetes have significantly improved during this period, but glycemic control was still poorer than that in other developed countriesope

    Critical current densities and flux creep rates in near optimally doped BaFe2-xRuxAs2 (x≈0.7) single crystals

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    We present an investigation of the critical current densities Jc and flux creep rates in a near optimally doped BaFe2-xRuxAs2 (x≈0.7) single crystal by (measuring magnetization). The superconducting critical temperature is 18 K. The in-field dependences of the critical current density Jc are due to a mixed pinning scenario produced mainly by large precipitates and a less significant contribution of random disorder. Furthermore, a Maley analysis in the regime dominated by strong pinning centers (μ0H=0.1 T) is well described through a glassy exponent μ=1.9 and a collective pinning energy (U0) smaller than 100 K.Fil: Haberkorn, Nestor Fabian. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Eom, Man Jin. Pohang University of Science and Technology; Corea del SurFil: You, Jung Sang. Pohang University of Science and Technology; Corea del SurFil: Kim, Jeehoon. Pohang University of Science and Technology; Corea del SurFil: Kim, Jun Sung. Pohang University of Science and Technology; Corea del Su

    Intraosseous Hemangioma of the Middle Turbinate Misdiagnosed As a Nasal Polyp

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    Intraosseous hemangiomas account for 1% of all bone tumors and primarily originate from the vertebral column and skull bones. However, intraosseous hemangiomas of the nasal cavity are extremely rare. Here, we report a case of intraosseous hemangioma with a cavernous pattern arising from the middle turbinate that was preoperatively misdiagnosed as chronic rhinosinusitis with polyps. Except for nasal obstruction, there were no specific rhinologic symptoms. The tumor was excised en bloc by the endoscopic endonasal approach without preoperative embolization

    Optimizing Ship Speed to Minimize Total Fuel Consumption with Multiple Time Windows

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    We study the ship speed optimization problem with the objective of minimizing the total fuel consumption. We consider multiple time windows for each port call as constraints and formulate the problem as a nonlinear mixed integer program. We derive intrinsic properties of the problem and develop an exact algorithm based on the properties. Computational experiments show that the suggested algorithm is very efficient in finding an optimal solution
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