173 research outputs found

    Magnetic phase diagram of the spin-1/2 antiferromagnetic zigzag ladder

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    We study the one-dimensional spin-1/2 Heisenberg model with antiferromagnetic nearest-neighbor J_1 and next-nearest-neighbor J_2 exchange couplings in magnetic field h. With varying dimensionless parameters J_2/J_1 and h/J_1, the ground state of the model exhibits several phases including three gapped phases (dimer, 1/3-magnetization plateau, and fully polarized phases) and four types of gapless Tomonaga-Luttinger liquid (TLL) phases which we dub TLL1, TLL2, spin-density-wave (SDW_2), and vector chiral phases. From extensive numerical calculations using the density-matrix renormalization-group method, we investigate various (multiple-)spin correlation functions in detail, and determine dominant and subleading correlations in each phase. For the one-component TLLs, i.e., the TLL1, SDW_2, and vector chiral phases, we fit the numerically obtained correlation functions to those calculated from effective low-energy theories of TLLs, and find good agreement between them. The low-energy theory for each critical TLL phase is thus identified, together with TLL parameters which control the exponents of power-law decaying correlation functions. For the TLL2 phase, we develop an effective low-energy theory of two-component TLL consisting of two free bosons (central charge c=1+1), which explains numerical results of entanglement entropy and Friedel oscillations of local magnetization. Implications of our results to possible magnetic phase transitions in real quasi-one-dimensional compounds are also discussed.Comment: 22 pages, 17 figures. v2: published versio

    キーンベック病に対する手関節背側からの血管柄付骨移植術

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    Purpose The objective of this article is to evaluate functional and radiological outcomes of vascularized bone grafts for stage 2 and 3 Kienböck disease. The outcomes of three different donor sites via dorsal approach of the wrist were compared. Pearls and pitfalls in surgical technique were discussed. Methods There were 28 patients who underwent vascularized bone grafts, including the extensor fourth and fifth compartmental artery graft of distal radius in 8 patients, the first and second supraretinacular intercompartmental artery graft of distal radius in 12 patients, and the second dorsal metacarpal neck graft in 8 patients. Average age was 32 years, and radiological grading according to Lichtman classification was stage 2 in 8 patients, stage 3A in 10 patients, and stage 3B in 10 patients. Temporary pinning fixing the midcarpal joint was conducted for 10 weeks postoperatively. Results Follow-up periods averaged 70 months. Pain reduced in 27 patients, and visual analog scale for pain of pre- and postoperative level averaged 59 and 18. Range of wrist flexion and extension motion improved from 87 to 117 degrees, and average grip strength improved from 21 kg preoperatively to 33 kg postoperatively. Carpal height ratio had almost no change from 0.52 to 0.53. Fragmentation of necrotic bone healed in 7 of the 14 cases. Comparative analyses of functional and radiological outcomes between three donor sites found no significant difference. Conclusion Three different vascularized bone grafts from the dorsal wrist and hand area demonstrated favorable and comparable functional outcomes. It was technically important to elevate vascular bundle with surrounding retinaculum or fascia, to include sufficient periosteum, and to insert the vascularized bone as the cortex aligned longitudinally.博士(医学)・乙第1385号・平成28年11月24日最終稿掲載不可のため本文の掲載無し(国立国会図書館には送付済み

    Deformation Behavior and Workability of Supercooled Liquid in Zr_<65>Al_<10>Ni_<10>Cu_<15> Metallic Glass

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    The tensile deformation behavior and the workability of Zr_Al_Ni_Cu_ Metallic Glass with a wide supercooled liquid have been examined. The glassy solid exhibited the homogeneous deformation at higher temperatures and lower strain rates. The supercooled liquid revealed a homogeneous deformation even at high strain rates above 0.5 s^. The strength in the homogeneous deformation region was lower at higher temperatures and lower strain rates. The supercooled liquid exhibited similar deformation behavior to the other high-strain-rate superplastic materials. Using this superplastic-like deformation in the supercooled liquid, complex-shaped glassy component with original strength was produced through an extrusion process

    Transpupillary thermotherapy for atypical central serous chorioretinopathy

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    Ryosuke Kawamura1,2, Hidenao Ideta1, Hideyuki Hori1, Kenya Yuki2, Tsuyoshi Uno1, Tatsurou Tanabe1, Kazuo Tsubota2, Tsutomu Kawasaki11Ideta Eye Hospital, Kumamoto, Japan; 2Keio University, School of Medicine, Department of Ophthalmology, Tokyo, JapanBackground: Central serous chorioretinopathy (CSC) has been traditionally treated with laser photocoagulation. We thought that transpupillary thermotherapy (TTT) utilizing a lower temperature than that of conventional laser photocoagulation might minimize permanent retinal and choroidal damage. Studies suggest that undesirable effects on vision due to TTT are minimal even if it is applied to foveal and/or parafoveal lesions when TTT requires a larger irradiation spot. The aim of this study was to evaluate the efficacy of TTT in the management of atypical CSC.Methods: We defined atypical CSC as bullous retinal detachment with diffuse or several leakages, severe leakage with fibrin formation under serous retinal detachment, or leakage within a pigment epithelium detachment. Eight consecutive patients with atypical CSC underwent visual acuity testing, ophthalmic examination, color photography, fluorescein angiography, and optical coherence tomography to evaluate the results of transpupillary thermotherapy. Retreatment of atypical CSC was based on ophthalmic examination, optical coherence tomography, and fluorescein angiography. TTT was performed on the leaking spots shown in fluorescein angiography, with a power of 50&amp;ndash;250 mW, spot size of 500&amp;ndash;1200 &amp;micro;m, and exposure time of 13&amp;ndash;60 seconds to minimize retinal damage.Results: In five of eight affected eyes, serous detachments completely resolved within 1 month after the initial TTT. One eye had persistent subretinal fluid and required a second TTT treatment. Two eyes showed no resolution of CSC and were treated by conventional photocoagulation. Initial best-corrected visual acuity (BCVA) ranged from 20/600 to 20/20 (mean, 20/40; median, 20/30). Final BCVA ranged from 20/200 to 20/20 (mean, 20/25; median, 20/20). BCVA improved in all cases. Only two eyes with persistent subretinal fibrin and existing retinal pigment epithelial alternations in macular area showed limited improvement of BCVA despite the absence of subretinal exudation. The presence of retinal attachment was confirmed by optical coherence tomography in six eyes (75%).Conclusions: TTT seems to be effective for the treatment of atypical CSC in the short term. Additional studies are necessary to evaluate the long-term effectiveness and safety.Keywords: transpupillary thermotherapy, central serous chorioretinopathy, optical coherence tomography, fluorescein angiography, serous detachmen

    Changes in 12-Year First-Line Eradication Rate of Helicobacter pylori Based on Triple Therapy with Proton Pump Inhibitor, Amoxicillin and Clarithromycin

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    A triple therapy based on a proton pump inhibitor (PPI), amoxicillin (AMPC), and clarithromycin (CAM) is recommended as a first-line therapy for Helicobacter pylori (H. pylori) eradication and is widely used in Japan. However, a decline in eradication rate associated with an increase in prevalence of CAM resistance is viewed as a problem. We investigated CAM resistance and eradication rates over time retrospectively in 750 patients who had undergone the triple therapy as first-line eradication therapy at Nagoya City University Hospital from 1995 to 2008, divided into four terms (Term 1: 1997–2000, Term 2: 2001–2003, Term 3: 2004–2006, Term 4: 2007–2008). Primary resistance to CAM rose significantly over time from 8.7% to 23.5%, 26.7% and 34.5% while the eradication rate decreased significantly from 90.6% to 80.2%, 76.0% and 74.8%. Based on the PPI type, significant declines in eradication rates were observed with omeprazole or lansoprazole, but not with rabeprazole. A decrease in the H. pylori eradication rate after triple therapy using a PPI + AMPC + CAM has been acknowledged, and an increase in CAM resistance is considered to be a factor. From now on, a first-line eradication regimen that results in a higher eradication rate ought to be investigated

    Development of a non-destructive depth-selective quantification method for sub-percent carbon contents in steel using negative muon lifetime analysis

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    鋼鉄の品質管理・日本刀など文化財の非破壊分析も 鋼鉄中のわずかな炭素を素粒子で透視する --ミュオンによる新しい非破壊微量軽元素分析法の開発--. 京都大学プレスリリース. 2024-02-09.The amount of C in steel, which is critical in determining its properties, is strongly influenced by steel production technology. We propose a novel method of quantifying the bulk C content in steel non-destructively using muons. This revolutionary method may be used not only in the quality control of steel in production, but also in analyzing precious steel archaeological artifacts. A negatively charged muon forms an atomic system owing to its negative charge, and is finally absorbed into the nucleus or decays to an electron. The lifetimes of muons differ significantly, depending on whether they are trapped by Fe or C atoms, and identifying the elemental content at the muon stoppage position is possible via muon lifetime measurements. The relationship between the muon capture probabilities of C/Fe and the elemental content of C exhibits a good linearity, and the C content in the steel may be quantitatively determined via muon lifetime measurements. Furthermore, by controlling the incident energies of the muons, they may be stopped in each layer of a stacked sample consisting of three types of steel plates with thicknesses of 0.5 mm, and we successfully determined the C contents in the range 0.20–1.03 wt% depth-selectively, without sample destruction

    Magnetization plateau in a two-dimensional multiple-spin exchange model

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    We study a multiple-spin exchange model on a triangular lattice, which is a possible model for low-density solid 3He films. Due to strong competitions between ferromagnetic three-spin exchange and antiferromagnetic four-spin one, the ground states are highly degenerate in the classical limit. At least 2^{L/2}-fold degeneracy exists on the L*L triangular lattice except for the SO(3) symmetry. In the magnetization process, we found a plateau at m/m_{sat}=1/2, in which the ground state is "uuud state" (a collinear state with four sublattices). The 1/2-plateau appears due to the strong four-spin exchange interaction. This plateau survives against both quantum and thermal fluctuations. Under a magnetic field which realizes the "uuud" ordered state, a phase transition occurs at a finite temperature. We predict that low-density solid 3He thin films may show the 1/2-plateau in the magnetization process. Experimental observation of the plateau will verify strength of the four-spin exchange. It is also discussed that this magnetization plateau can be understood as an insulating-conducting transition in a particle picture.Comment: 10 pages, RevTeX, 12 figures, added a reference and corrected typos, to be published in Phys.Rev.B (01 APR 99

    Development of a non-destructive depth-selective quantification method for sub-percent carbon contents in steel using negative muon lifetime analysis

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    Ninomiya K., Kubo M.K., Inagaki M., et al. Development of a non-destructive depth-selective quantification method for sub-percent carbon contents in steel using negative muon lifetime analysis. Scientific Reports 14, 1797 (2024); https://doi.org/10.1038/s41598-024-52255-5.The amount of C in steel, which is critical in determining its properties, is strongly influenced by steel production technology. We propose a novel method of quantifying the bulk C content in steel non-destructively using muons. This revolutionary method may be used not only in the quality control of steel in production, but also in analyzing precious steel archaeological artifacts. A negatively charged muon forms an atomic system owing to its negative charge, and is finally absorbed into the nucleus or decays to an electron. The lifetimes of muons differ significantly, depending on whether they are trapped by Fe or C atoms, and identifying the elemental content at the muon stoppage position is possible via muon lifetime measurements. The relationship between the muon capture probabilities of C/Fe and the elemental content of C exhibits a good linearity, and the C content in the steel may be quantitatively determined via muon lifetime measurements. Furthermore, by controlling the incident energies of the muons, they may be stopped in each layer of a stacked sample consisting of three types of steel plates with thicknesses of 0.5 mm, and we successfully determined the C contents in the range 0.20–1.03 wt% depth-selectively, without sample destruction

    Large-scale analysis of full-length cDNAs from the tomato (Solanum lycopersicum) cultivar Micro-Tom, a reference system for the Solanaceae genomics

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    <p>Abstract</p> <p>Background</p> <p>The Solanaceae family includes several economically important vegetable crops. The tomato (<it>Solanum lycopersicum</it>) is regarded as a model plant of the Solanaceae family. Recently, a number of tomato resources have been developed in parallel with the ongoing tomato genome sequencing project. In particular, a miniature cultivar, Micro-Tom, is regarded as a model system in tomato genomics, and a number of genomics resources in the Micro-Tom-background, such as ESTs and mutagenized lines, have been established by an international alliance.</p> <p>Results</p> <p>To accelerate the progress in tomato genomics, we developed a collection of fully-sequenced 13,227 Micro-Tom full-length cDNAs. By checking redundant sequences, coding sequences, and chimeric sequences, a set of 11,502 non-redundant full-length cDNAs (nrFLcDNAs) was generated. Analysis of untranslated regions demonstrated that tomato has longer 5'- and 3'-untranslated regions than most other plants but rice. Classification of functions of proteins predicted from the coding sequences demonstrated that nrFLcDNAs covered a broad range of functions. A comparison of nrFLcDNAs with genes of sixteen plants facilitated the identification of tomato genes that are not found in other plants, most of which did not have known protein domains. Mapping of the nrFLcDNAs onto currently available tomato genome sequences facilitated prediction of exon-intron structure. Introns of tomato genes were longer than those of Arabidopsis and rice. According to a comparison of exon sequences between the nrFLcDNAs and the tomato genome sequences, the frequency of nucleotide mismatch in exons between Micro-Tom and the genome-sequencing cultivar (Heinz 1706) was estimated to be 0.061%.</p> <p>Conclusion</p> <p>The collection of Micro-Tom nrFLcDNAs generated in this study will serve as a valuable genomic tool for plant biologists to bridge the gap between basic and applied studies. The nrFLcDNA sequences will help annotation of the tomato whole-genome sequence and aid in tomato functional genomics and molecular breeding. Full-length cDNA sequences and their annotations are provided in the database KaFTom <url>http://www.pgb.kazusa.or.jp/kaftom/</url> via the website of the National Bioresource Project Tomato <url>http://tomato.nbrp.jp</url>.</p
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