685 research outputs found

    Probing onset of strong localization and electron-electron interactions with the presence of direct insulator-quantum Hall transition

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    We have performed low-temperature transport measurements on a disordered two-dimensional electron system (2DES). Features of the strong localization leading to the quantum Hall effect are observed after the 2DES undergoes a direct insulator-quantum Hall transition with increasing the perpendicular magnetic field. However, such a transition does not correspond to the onset of strong localization. The temperature dependences of the Hall resistivity and Hall conductivity reveal the importance of the electron-electron interaction effects to the observed transition in our study.Comment: 9 pages, 4 figure

    Optimal Color Stability for White Organic Light-Emitting Diode (WOLED) by Using Multiple-Ultra-Thin Layers (MUTL)

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    The work demonstrates the improvement of color stability for white organic light-emitting diode (WOLED). The devices were prepared by vacuum deposition on ITO-glass substrates. These guest materials of 5,6,11,12-tetraphenylnaphthacene (Rubrene) were deposited in 4,4′-bis(2,2-diphenyl vinyl)-1,1′-biphenyl (DPVBi), resulting in an emitting layer. Experimental results reveal that the properties in the multiple-ultra-thin layer (MUTL) are better than those of the emitting layer with a single guest material, reaching the commercial white-light wavelength requirement of 400–700 nm. The function of the MUTL is as the light-emitting and trapping layer. The results show that the MUTL has excellent carrier capture effect, leading to high color stability of the device at various applied voltages. The Commissions Internationale De L’Eclairage (CIE) coordinate of this device at 3~7 V is few displacement and shows a very slight variation of (0.016, 0.009). The CIE coordinates at a maximal luminance of 9980 cd/m2 are (0.34, 0.33)

    Minimally invasive strategy for gynecologic cancer with solitary periacetabular metastasis

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    SummaryTumor with bone metastases to the periacetabulum is rare, and its surgical management is challenging. Instead of wide excision with reconstruction of the hip joint, we used a relatively noninvasive method to manage periacetabular metastasis. Such a procedure for this condition has the benefits of short surgical time, less bleeding, and fewer complications during surgery. Our surgical management of the case reported here included curettage, phenol cauterization and filling of cisplatin-loaded cement in order to reduce local recurrence. After following-up for 2 years, there was no local recurrence and disease progression

    First-order magnetic and structural phase transitions in Fe1+y_{1+y}Sex_xTe1x_{1-x}

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    We use bulk magnetic susceptibility, electronic specific heat, and neutron scattering to study structural and magnetic phase transitions in Fe1+y_{1+y}Se% x_xTe1x_{1-x}. Fe1.068_{1.068}Te exhibits a first order phase transition near 67 K with a tetragonal to monoclinic structural transition and simultaneously develops a collinear antiferromagnetic (AF) order responsible for the entropy change across the transition. Systematic studies of FeSe%_{1-x}Tex_x system reveal that the AF structure and lattice distortion in these materials are different from those of FeAs-based pnictides. These results call into question the conclusions of present density functional calculations, where FeSe1x_{1-x}Tex_x and FeAs-based pnictides are expected to have similar Fermi surfaces and therefore the same spin-density-wave AF order.Comment: 5 pages, 3 figure

    Subcutaneous nerve activity is more accurate than heart rate variability in estimating cardiac sympathetic tone in ambulatory dogs with myocardial infarction

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    BACKGROUND: We recently reported that subcutaneous nerve activity (SCNA) can be used to estimate sympathetic tone. OBJECTIVE: The purpose of this study was to test the hypothesis that left thoracic SCNA is more accurate than heart rate variability (HRV) in estimating cardiac sympathetic tone in ambulatory dogs with myocardial infarction (MI). METHODS: We used an implanted radiotransmitter to study left stellate ganglion nerve activity (SGNA), vagal nerve activity (VNA), and thoracic SCNA in 9 dogs at baseline and up to 8 weeks after MI. HRV was determined based on time-domain, frequency-domain, and nonlinear analyses. RESULTS: The correlation coefficients between integrated SGNA and SCNA averaged 0.74 (95% confidence interval [CI] 0.41-1.06) at baseline and 0.82 (95% CI, 0.63-1.01) after MI (P <.05 for both). The absolute values of the correlation coefficients were significantly larger than that between SGNA and HRV analysis based on time-domain, frequency-domain, and nonlinear analyses, respectively, at baseline (P <.05 for all) and after MI (P <.05 for all). There was a clear increment of SGNA and SCNA at 2, 4, 6, and 8 weeks after MI, whereas HRV parameters showed no significant changes. Significant circadian variations were noted in SCNA, SGNA, and all HRV parameters at baseline and after MI, respectively. Atrial tachycardia (AT) episodes were invariably preceded by SCNA and SGNA, which were progressively increased from 120th, 90th, 60th, to 30th seconds before AT onset. No such changes of HRV parameters were observed before AT onset. CONCLUSION: SCNA is more accurate than HRV in estimating cardiac sympathetic tone in ambulatory dogs with MI
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