498 research outputs found

    Observation of finite excess noise in the voltage-biased quantum Hall regime as a precursor for breakdown

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    We performed noise measurements in a two-dimensional electron gas to investigate the nonequilibrium quantum Hall effect (QHE) state. While excess noise is perfectly suppressed around the zero-biased QHE state reflecting the dissipationless electron transport of the QHE state, considerable finite excess noise is observed in the breakdown regime of the QHE. The noise temperature deduced from the excess noise is found to be of the same order as the energy gap between the highest occupied Landau level and the lowest empty one. Moreover, unexpected finite excess noise is observed at a finite source-drain bias voltagesmaller than the onset voltage of the QHE breakdown, which indicates finite dissipation in the QHE state and may be related to the prebreakdown of the QHE.Comment: 8 pages, 8 figure

    Kampo Medicines for Mite Antigen-Induced Allergic Dermatitis in NC/Nga Mice

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    We have established an allergic dermatitis model in NC/Nga mice by repeated local exposure of mite antigen for analyzing atopic dermatitis. We examined how four Kampo medicines, Juzen-taiho-to, Hochu-ekki-to, Shofu-san and Oren-gedoku-to, on the dermatitis model to obtain basic information on their usefulness for treating atopic dermatitis. Mite antigen (Dermatophagoides farinae crude extract) solution at a concentration of 10 mg/ml was painted on the ear of NC/Nga mice after tape stripping. The procedure was repeated five times, at 7 day intervals. An apparent biphasic ear swelling was caused after the fourth and fifth antigen exposures with elevated serum IgE levels and accumulation of inflammatory cells. In the cervical lymph nodes and ear lobes, the five procedures of antigen exposure induced interleukin-4 mRNA expression but reduced interferon-γ mRNA expression. Oral administration of all four Kampo medicines inhibited the formation of ear swelling and inflammatory cell accumulation. Juzen-taiho-to and Hochu-ekki-to apparently prevented the elevation of serum IgE level. Furthermore, the four Kampo medicines showed a tendency to prevent not only the increase in interleukin-4 mRNA expression but also the decrease in interferon-γ mRNA expression. The present results indicate that Juzen-taiho-to, Hochu-ekki-to, Shofu-san and Oren-gedoku-to may correct the Th1/Th2 balance skewed to Th2, and this activity helps inhibit dermatitis in NC/Nga mice. The ability of the Kampo medicines to correct the Th1/Th2 balance seems to underlie their effectiveness in treating of atopic dermatitis

    The inhibitory effects of Orengedokuto on inducible PGE2 production in BV-2 microglial cells

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    [Background and aim] Reactive microglia has been associated with neuroinflammation caused by the production of proinflammatory molecules such as cytokines, nitric oxide, and prostaglandins. The overexpression of these molecules may provoke neuronal damage that can cause neurodegenerative diseases. A traditional herbal medicine, Orengedokuto (OGT), has been widely used for treating inflammation-related diseases. However, how it influences neuroinflammation remains poorly understood. [Experimental procedure] This study investigated the effects of OGT on inflammatory molecule induction in BV-2 microglial cells using real-time RT-PCR and ELISA. An in vivo confirmation of these effects was then performed in mice. [Results and conclusion] OGT showed dose-dependent inhibition of prostaglandin E2 (PGE2) production in BV-2 cells stimulated with lipopolysaccharide (LPS). To elucidate the mechanism of PGE2 inhibition, we examined cyclooxygenases (COXs) and found that OGT did not suppress COX-1 expression or inhibit LPS-induced COX-2 upregulation at either the transcriptional or translational levels. In addition, OGT did not inhibit COX enzyme activities within the concentration that inhibited PGE2 production, suggesting that the effect of OGT is COX-independent. The inhibitory effects of OGT on PGE2 production in BV-2 cells were experimentally replicated in primary cultured astrocytes and mice brains. OGT can be useful in the treatment of neuroinflammatory diseases by modulating PGE2 expression

    Spiral Tissue Microarrays as Next Evolutionary Step in the High-density Tissue Microarray Technology

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    Tissue microarray (TMA) is a well-established technique that connects basic research with clinical applications that allow the validation of many pathobiologic events from gene expression dysregulation to genomic aberrations. However, conventional TMAs have several limitations such as limited representation of tissue heterogeneity, destruction of donor tissue blocks due to coring and usage of particular specimens that have limited evaluable material (tissue from thin specimens or needle biopsies). We have developed a novel method, which we termed "Spiral TMA" that generates TMAs that allow for improved representation of the donor tissue while keeping the architectural details of the donor block intact. This technology is ideal for specimens with limited tissue without the need to punch holes into the original block and therefore preserving the tissue integrity. In this report, we describe the methodology of constructing Spiral TMA and demonstrate the validation of tumor representation and tissue heterogeneity by comparing Spiral TMA to conventional TMA using immunohistochemical staining to EGFR and CK7

    A new quadruple gravitational lens from the Hyper Suprime-Cam Survey: the puzzle of HSC~J115252+004733

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    We report the serendipitous discovery of a quadruply lensed source at zs=3.76z_{\rm s}=3.76, HSC~J115252+004733, from the Hyper Suprime-Cam (HSC) Survey. The source is lensed by an early-type galaxy at zl=0.466z_{\rm l}=0.466 and a satellite galaxy. Here, we investigate the properties of the source by studying its size and luminosity from the imaging and the luminosity and velocity width of the Ly-α\alpha line from the spectrum. Our analyses suggest that the source is most probably a low-luminosity active galactic nucleus (LLAGN) but the possibility of it being a compact bright galaxy (e.g., a Lyman-α\alpha emitter or Lyman Break Galaxy) cannot be excluded. The brighter pair of lensed images appears point-like except in the HSC ii-band (with a seeing 0.5"\sim0.5"). The extended emission in the ii-band image could be due to the host galaxy underneath the AGN, or alternatively, due to a highly compact lensed galaxy (without AGN) which appears point-like in all bands except in ii-band. We also find that the flux ratio of the brighter pair of images is different in the Ks-band compared to optical wavelengths. Phenomena such as differential extinction and intrinsic variability cannot explain this chromatic variation. While microlensing from stars in the foreground galaxy is less likely to be the cause, it cannot be ruled out completely. If the galaxy hosts an AGN, then this represents the highest redshift quadruply imaged AGN known to date, enabling study of a distant LLAGN. Discovery of this unusually compact and faint source demonstrates the potential of the HSC survey.Comment: 9 pages, 7 figures, 3 Tables, MNRAS accepted, text reduce
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