208 research outputs found

    Electro-spinon in one-dimensional Mott insulator

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    The low-energy dynamical optical response of dimerized and undimerized spin liquid states in a one-dimensional charge transfer Mott insulator is theoretically studied. An exact analysis is given for the low-energy asymptotic behavior using conformal field theory for the undimerized state. In the dimerized state, the infrared absorption due to the bound state of two solitons, i.e, the breather mode, is predicted with an accurate estimate for its oscillator strength, offering a way to detect experimentally the excited singlet state. Effects of external magnetic fields are also discussed.Comment: 5 pages, 2 figures, some typos are correcte

    Electrical conductivity of basaltic and carbonatite melt-bearing peridotites at high pressures: Implications for melt distribution and melt fraction in the upper mantle

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    International audienceElectrical impedance measurements were performed on two types of partial molten samples with basaltic and carbonatitic melts in a Kawai-type multi-anvil apparatus in order to investigate melt fraction-conductivity relationships and melt distribution of the partial molten mantle peridotite under high pressure. The silicate samples were composed of San Carlos olivine with various amounts of mid-ocean ridge basalt (MORB), and the carbonate samples were a mixture of San Carlos olivine with various amounts of carbonatite. High-pressure experiments on the silicate and carbonate systems were performed up to 1600 K at 1.5 GPa and up to at least 1650 K at 3 GPa, respectively. The sample conductivity increased with increasing melt fraction. Carbonatite-bearing samples show approximately one order of magnitude higher conductivity than basalt-bearing ones at the similar melt fraction. A linear relationship between log conductivity (σbulk) and log melt fraction (phi) can be expressed well by the Archie's law (Archie, 1942) (σbulk/σmelt = Cphin) with parameters C = 0.68 and 0.97, n = 0.87 and 1.13 for silicate and carbonate systems, respectively. Comparison of the electrical conductivity data with theoretical predictions for melt distribution indicates that the model assuming that the grain boundary is completely wetted by melt is the most preferable melt geometry. The gradual change of conductivity with melt fraction suggests no permeability jump due to melt percolation at a certain melt fraction. The melt fraction of the partial molten region in the upper mantle can be estimated to be 1-3% and not, vert, similar 0.3% for basaltic melt and carbonatite melt, respectively

    Electrical conductivity of partial molten carbonate peridotite

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    International audienceIn order to investigate the effect of carbonate-content in partial melt on bulk conductivity under high pressure, electrical conductivity measurements were performed on carbonate melt-bearing peridotites using a Kawai-type multi-anvil apparatus. The starting materials were composed of spinel lherzolite (KLB1) with small amounts of dolomite (1 and 3 wt.%). To obtain various melt fractions, annealing experiments were performed at different temperatures above 1400 K at 3 GPa. At low temperatures (⩽ 1500 K), the conductivity was distinctly higher than that of carbonate-free peridotite and close to that of the carbonatite melt-bearing olivine aggregates. Although the sample conductivity increased with increasing temperature, the rate at which the conductivity increases was small and the conductivity approached that of silicate melt-bearing peridotite. CO2 concentration in the partial melt decreased with increasing annealing temperature. Thus, the small increase of the conductivity with annealing temperature is attributed to a decrease of the melt conductivity due to a decrease in carbonate content in the partial melt. As the carbonate concentration in the melt decreases, the estimated melt conductivity approaches that of the basaltic melt. Therefore, conductivity enhancement by the carbonate-bearing melt is very effective at temperature just above that of the carbonate peridotite solidus

    Position Heaps for Parameterized Strings

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    We propose a new indexing structure for parameterized strings, called parameterized position heap. Parameterized position heap is applicable for parameterized pattern matching problem, where the pattern matches a substring of the text if there exists a bijective mapping from the symbols of the pattern to the symbols of the substring. We propose an online construction algorithm of parameterized position heap of a text and show that our algorithm runs in linear time with respect to the text size. We also show that by using parameterized position heap, we can find all occurrences of a pattern in the text in linear time with respect to the product of the pattern size and the alphabet size

    Prevalence of Hypertension, Diabetes Mellitus, and Dyslipidemia in Patients with Chronic Obstructive Pulmonary Disease

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    Recent studies have shown that chronic obstructive pulmonary disease (COPD) causes various extrapulmonary comorbidities. In addition, cardiovascular disease, the pathogenesis of which involves atherosclerosis, has been emphasized as a cause of mortality in patients with COPD. In the present study, we investigated the presence of classical risk factors for atherosclerosis in 183 patients with COPD. The prevalence of comorbidities (hypertension, diabetes mellitus [DM], and dyslipidemia) was investigated and compared with that in a general population. In patients with COPD, the prevalence of hypertension, DM, and dyslipidemia was 43.2%, 15.8%, and 25.7%, respectively, with the prevalence of DM and dyslipidemia significantly higher in patients than in the general population. Furthermore, there were significant differences in the prevalence of the three disorders in patients with COPD. For example, the prevalence of hypertension was significantly higher than that of diabetes mellitus in patients aged 60-69 years and higher than the prevalence of DM and dyslipidemia in patients aged ≥ 70 years. Regardless of age, hypertension was noted in the greatest number of patients. In conclusion, a high proportion of patients with COPD were found to have the classical risk factors for atherosclerosis. In particular, the prevalence of DM and dyslipidemia was significantly higher in COPD patients than in the general population

    Mineralogy of Granulite Facies Rocks in the Area around Lutzow-Holm Bay, Antarctica

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    The chemical compositions of constituent minerals of metamorphic rocks of the area around Lutzow-Holm Bay in Antarctica are described along with their optic properties. The mineralogy and paragenesis of metamorphic rocks are interpreted as that the metamorphic rocks in this terrane belong to the granulite facies

    Desensitization of delayed-type hypersensitivity in mice: suppressive environment

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    The systemic injection of high doses of antigen into a preimmunized animal results in transient unresponsiveness of cell-mediated immune responses. This phenomenon is known as desensitization. Serum interleukin 2 (IL-2) activity was found transiently in desensitized mice at 3 h after the antigen challenge. These mice could not reveal antigen nonspecific delayed-type hypersensitivity (DTH) 1 d after the challenge. Specific suppression of DTH was observed at later stages. Sera from 3 h desensitized mice showed suppressive effects on DTH in preo immunized mice. Administration of recombinant IL-2 into preimmunized mice led to the failure of development of DTH to antigens. These observations suggest that IL-2 plays an important role in the suppressive environment

    Design and simulation tool for ground source heat pump systems considering groundwater advection

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    Calculation of the underground temperature resulting from heat injection/extraction into/from ground heat exchangers (GHEXs) with hourly variation is one of the most noteworthy challenges to address when simulating and designing a ground source heat pump (GSHP) system. Especially in Japan, considering the groundwater flow is desirable because there is the possibility to reduce the installation cost for GSHP system. In order to overcome this challenge, the authors introduce a method to calculate the underground temperature, by considering heat injection/extraction into/from GHEXs with hourly variation. The method applies the superposition of the Moving Infinite Cylindrical Source (MICS) solution and the Moving Infinite Line Source (MILS) solution to calculate the temperature change due to heat injection/extraction into/from the certain GHEX and other neighboring GHEXs, respectively. In this paper, the outlines of the MICS and the method that calculate the MICS solution were firstly introduced. Next, the calculation method of underground temperature and the simulation model for the GSHP system were explained. Finally, the temperature variations of the heat carrier fluid were calculated by changing the conditions the geological layer and groundwater velocity

    A case of a middle-aged patient with a ventricular septal defect complicated by severe pulmonary hypertension-stepwise surgical repair with pulmonary vasodilators-

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    We report a case of ventricular septal defect (VSD) in which we attempted to treat pulmonary arterial hypertension (PAH) with the goal of VSD closure in an adult with suspected Eisenmenger syndrome in childhood. Four years previously (age 41 years), she was referred to our department due to repeated hemoptysis requiring further treatment of PAH. We started combination therapy with several pulmonary vasodilators. Two years later, her pulmonary vascular resistance (PVR) was improved but still not at the level where VSD closure was possible. To control the increased PA flow resulting from intensive PAH treatment and to reduce the risk of hemoptysis, we performed pulmonary artery banding (PAB). As the risk of hemoptysis decreased, a prostacyclin analog was introduced, and the dose was increased. More than 1 year after PAB, active vasoactivity testing became positive, suggesting that the pulmonary vascular lesion was now “reversible”. We performed VSD closure and atrial septal defect creation even though her PVR was still high. After the operation, her exercise capacity was remarkably improved. We suggest that stepwise surgical repair with pulmonary vasodilators is an important treatment option for select patients with VSD with severe PAH.Learning objectiveAdvances in pulmonary arterial hypertension (PAH) treatment have led to the use of a “treat-and-repair” strategy to close the intracardiac shunt after PAH treatment in select patients with adult congenital heart disease. In our case, ventricular septal defect (VSD) closure was achieved with stepwise surgical repair and a combination of pulmonary vasodilators, even though long-standing severe PAH with persistent hemoptysis remained. Even after a long period of exposure to high blood flow, this strategy may reduce pulmonary vascular resistance and permit eventual closure of the VSD
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