774 research outputs found

    Sol-gel synthesis of molecular sieving silica membranes

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    Polymeric silica sol was synthesized by the acid catalyzed hydrolysis and condensation of tetra-ethyl-ortho-silicate. Calcined unsupported membranes made from this sol showed microporous nature. Supported membranes on alumina were prepared by dipping and calcining. Helium showed activated diffusion with an apparent activation energy of 17 kJ mol−1. H2 permeation was comparable to that of helium under identical conditions. N2, Ar, O2, C3H6, C3H8, n-C4H10 and i-C4H10 permeation values were extremely small and therefore difficult to fit appropriate diffusion models. At 303 K hydrocarbon permeation was about 2 times higher than that of N2, Ar or O2. permselectivity around 1000 and helium permeation in the order of 10−7–10−8 mol m−2 s−1 Pa−1 were measured in the temperature range of 303–460 K. Comparison of Eact, selectivity and He and N2 permeation of different samples evidenced the dependence of nitrogen flux on processing defects. Obviously permeation rate of nitrogen molecule was insignificant through majority pores of the membrane

    Recent Result from E821 Experiment on Muon g-2 and Unconstrained Minimal Supersymemtric Standard Model

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    Recently, the E821 experiment at the Brookhaven National Laboratory announced their latest result of their muon g-2 measurement which is about 2.6-\sigma away from the standard model prediction. Taking this result seriously, we examine the possibility to explain this discrepancy by the supersymmetric contribution. Our analysis is performed in the framework of the unconstrained supersymmetric standard model which has free seven parameters relevant to muon g-2. We found that, in the case of large \tan\beta, sparticle masses are allowed to be large in the region where the SUSY contribution to the muon g-2 is large enough, and hence the conventional SUSY search may fail even at the LHC. On the contrary, to explain the discrepancy in the case of small \tan\beta, we found that (i) sleptons and SU(2)_L gauginos should be light, and (ii) negative search for the Higgs boson severely constrains the model in the framework of the mSUGRA and gauge-mediated model.Comment: 10 pages, 5 figure

    Anomaly-Mediated Supersymmetry Breaking with Axion

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    We construct hadronic axion models in the framework of the anomaly-mediated supersymmetry breaking scenario. If the Peccei-Quinn symmetry breaking is related to the supersymmetry breaking, mass spectrum of the minimal anomaly-mediated scenario is modified, which may solve the negative slepton mass problem in the minimal anomaly-mediated model. We find several classes of phenomenologically viable models of axion within the framework of the anomaly mediation and, in particular, we point out a new mechanism of stabilizing the axion potential. In this class of models, the Peccei-Quinn scale is related to the messenger scale. We also study phenomenological aspects of this class of models. We will see that, in some case, the lightest particle among the superpartners of the standard-model particles is stau while the lightest superparticle becomes the axino, the superpartner of the axion. With such a unique mass spectrum, conventional studies of the collider physics and cosmology for supersymmetric models should be altered.Comment: 20 pages, 5 figures, added footnotes and references for section

    No-Scale Scenarios in the Light of New Measurement of Muon Anomalous Magnetic Moment

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    Supersymmetric contribution to the muon anomalous magnetic moment a_\mu is discussed in the no-scale-type supersymmetry breaking scenarios. Taking the correlation between the supersymmetric contributions to a_\mu and Br(b\to s\gamma), it is shown that the precise measurements of these quantities serve an important constraint on the relative sign of the gaugino masses; combining the 2.6-\sigma deviation in a_\mu from the standard-model prediction measured by the E821 experiment and Br(b\to s\gamma) measured by CLEO, the sign of the product M_2M_3 is strongly preferred to be positive, where M_2 and M_3 are SU(2)_L and SU(3)_C gaugino mass parameters, respectively. In particular, no-scale-type models with universal gaugino masses are in accord with the two constraints and also with the Higgs mass bound. In addition, it is also shown that future improvements in the measurements of a_\mu and Br(b\to s\gamma) may provide serious test of the cases with M_2M_3<0.Comment: 10 pages, 4 figures, published versio

    The Effect of Dual-Hemisphere Transcranial Direct Current Stimulation Over the Parietal Operculum on Tactile Orientation Discrimination

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    The parietal operculum (PO) often shows ipsilateral activation during tactile object perception in neuroimaging experiments. However, the relative contribution of the PO to tactile judgment remains unclear. Here, we examined the effect of transcranial direct current stimulation (tDCS) over bilateral PO to test the relative contributions of the ipsilateral PO to tactile object processing. Ten healthy adults participated in this study, which had a double-blind, sham-controlled, cross-over design. Participants discriminated grating orientation during three tDCS and sham conditions. In the dual-hemisphere tDCS conditions, anodal and cathodal electrodes were placed over the left and right PO. In the uni-hemisphere tDCS condition, anodal and cathodal electrodes were applied over the left PO and contralateral orbit, respectively. In the tDCS and sham conditions, we applied 2 mA for 15 min and for 15 s, respectively. Computational models of electric fields (EFs) during tDCS indicated that the strongest electric fields were located in regions in and around the PO. Compared with the sham condition, dual-hemisphere tDCS improved the discrimination threshold of the index finger contralateral to the anodal electrode. Importantly, dual-hemisphere tDCS with the anodal electrode over the left PO yielded a decreased threshold in the right finger compared with the uni-hemisphere tDCS condition. These results suggest that the ipsilateral PO inhibits tactile processing of grating orientation, indicating interhemispheric inhibition (IHI) of the PO

    Immunohistochemistry or Molecular Analysis : Which Method Is Better for Subtyping Craniopharyngioma?

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    Craniopharyngioma (CP) is mainly classified into two pathological subtypes: adamantinomatous (ACP) and papillary (PCP). CTNNB1 (β-catenin) mutations are detected in ACPs, and the BRAF V600E mutation is detected in PCPs. However, genetic analysis is not always possible in general medical practice. In this study, we investigated whether immunohistochemistry could replace genetic analysis as an aid in subtype diagnosis. Here, 38 CP patients who had undergone their first tumor resection were included. Among the 38 cases, 22 were morphologically diagnosed as ACP, 10 cases were diagnosed as PCP, and six cases were diagnosed as undetermined CP that were morphologically difficult to classify as either ACP or PCP. Results of immunohistochemistry and genetic analysis and clinical features were compared. Based on the immunohistochemistry, 26 (22 ACPs and four undetermined CPs) showed nuclear β-catenin expression, 11 (nine PCPs and two undetermined CPs) exhibited positive BRAF V600E immunostaining and one PCP showed membranous β-catenin expression and negative for BRAF V600E immunostaining. Among the 26 nuclear β-catenin expression cases, 11 had CTNNB1 mutations; however, 15 cases had mutations of neither CTNNB1 nor BRAF V600E. All 11 BRAF V600E immunopositive cases had BRAF V600E mutations. When comparing clinical features between, pediatric patients and those with tumor calcification and less solid components on MRI more commonly had nuclear β-catenin expression tumors than BRAF V600E immunopositive tumors, reflecting the differences in clinical features between ACP and PCP. Accordingly, immunohistochemistry can replace genetic analysis as an aid to determine the subtype diagnosis of CP in general medical practice

    Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) III. Star formation properties of the host galaxies at z≳6z \gtrsim 6 studied with ALMA

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    We present our ALMA Cycle 4 measurements of the [CII] emission line and the underlying far-infrared (FIR) continuum emission from four optically low-luminosity (M1450>−25M_{\rm 1450} > -25) quasars at z≳6z \gtrsim 6 discovered by the Subaru Hyper Suprime Cam (HSC) survey. The [CII] line and FIR continuum luminosities lie in the ranges L[CII]=(3.8−10.2)×108 L⊙L_{\rm [CII]} = (3.8-10.2) \times 10^8~L_\odot and LFIR=(1.2−2.0)×1011 L⊙L_{\rm FIR} = (1.2-2.0) \times 10^{11}~L_\odot, which are at least one order of magnitude smaller than those of optically-luminous quasars at z≳6z \gtrsim 6. We estimate the star formation rates (SFR) of our targets as ≃23−40 M⊙ yr−1\simeq 23-40~M_\odot ~{\rm yr}^{-1}. Their line and continuum-emitting regions are marginally resolved, and found to be comparable in size to those of optically luminous quasars, indicating that their SFR or likely gas mass surface densities (key controlling parameter of mass accretion) are accordingly different. The L[CII]/LFIRL_{\rm [CII]}/L_{\rm FIR} ratios of the hosts, ≃(2.2−8.7)×10−3\simeq (2.2-8.7) \times 10^{-3}, are fully consistent with local star-forming galaxies. Using the [CII] dynamics, we derived their dynamical masses within a radius of 1.5-2.5 kpc as ≃(1.4−8.2)×1010 M⊙\simeq (1.4-8.2) \times 10^{10}~M_\odot. By interpreting these masses as stellar ones, we suggest that these faint quasar hosts are on or even below the star-forming main sequence at z∼6z \sim 6, i.e., they appear to be transforming into quiescent galaxies. This is in contrast to the optically luminous quasars at those redshifts, which show starburst-like properties. Finally, we find that the ratios of black hole mass to host galaxy dynamical mass of the most of low-luminosity quasars including the HSC ones are consistent with the local value. The mass ratios of the HSC quasars can be reproduced by a semi-analytical model that assumes merger-induced black hole-host galaxy evolution.Comment: 20 pages, 9 figures, 4 tables. Accepted for publication in PAS

    Growth hormone-producing pituitary adenomas in childhood and young adulthood : clinical features and outcomes

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    Purpose Growth hormone (GH)-producing pituitary adenomas (PAs) in childhood or young adulthood are rare, and the details surrounding these tumors remain enigmatic. We present the clinical, pathological and genetic features of this disease. Methods We identified 25 patients aged 20 years or younger with GH-producing PAs who underwent surgery between 2003 and 2016 at Toranomon Hospital in Tokyo. We retrospectively reviewed the clinical data, treatment outcomes and pathological features of these patients to shed light on childhood acromegaly. Results The cohort comprised 14 male and 11 female patients whose average age at the time of surgery was 17.3 years. Germline AIP mutations were present in 5 of 13 patients examined, and Carney complex was identified in 2 of 25 patients. The mean maximum tumor diameter was 26.7 mm, and total resection assessed during surgery was achieved in 17 patients. Based on their respective pathological findings, patients were divided into the following 4 groups: sparsely granulated adenomas (5), densely granulated (DG) adenomas (6), plurihormonal adenomas (9), and silent subtype 3 (SS3) adenomas (5). During the mean follow-up period of 50.3 months, complete endocrinological remission was achieved in 14 of 25 patients (56%) by surgery alone and in 19 patients (76%) after postoperative adjuvant therapy. Conclusions GH-producing PAs in young patients are intriguing and difficult to treat due to their distinct tumor characteristics, including a lower incidence of the DG subtype and a higher incidence of SS3 adenomas and genetic abnormalities. Therefore, multi-modal therapies are essential to achieve optimal clinical outcomes
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