112 research outputs found

    Theory of NMR as a local probe for the electronic structure in the mixed state of the high-TcT_c cuprates

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    We argue that nuclear magnetic resonance experiments are a site-sensitive probe for the electronic spectrum in the mixed state of the high-TcT_c cuprates. Within a spin-fermion model, we show that the Doppler-shifted electronic spectrum arising from the circulating supercurrent changes the low-frequency behavior of the imaginary part of the spin-susceptibility. For a hexagonal vortex lattice, we predict that these changes lead to {\it (a)} a unique dependence of the 63^{63}Cu spin lattice relaxation rate, 1/T11/T_1, on resonance frequency, and {\it (b)} a temperature dependence of T1T_1 which varies with frequency. We propose a nuclear quadrupole experiment to study the effects of a uniform supercurrent on the electronic structure and predict that T1T_1 varies with the direction of the supercurrent.Comment: RevTex, 5 pages, 3 figures embedded in the tex

    Physical Properties of (2) Pallas

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    We acquired and analyzed adaptive-optics imaging observations of asteroid (2) Pallas from Keck II and the Very Large Telescope taken during four Pallas oppositions between 2003 and 2007, with spatial resolution spanning 32-88 km (image scales 13-20 km/pix). We improve our determination of the size, shape, and pole by a novel method that combines our AO data with 51 visual light-curves spanning 34 years of observations as well as occultation data. The shape model of Pallas derived here reproduces well both the projected shape of Pallas on the sky and light-curve behavior at all the epochs considered. We resolved the pole ambiguity and found the spin-vector coordinates to be within 5 deg. of [long, lat] = [30 deg., -16 deg.] in the ECJ2000.0 reference frame, indicating a high obliquity of ~84 deg., leading to high seasonal contrast. The best triaxial-ellipsoid fit returns radii of a=275 km, b= 258 km, and c= 238 km. From the mass of Pallas determined by gravitational perturbation on other minor bodies [(1.2 +/- 0.3) x 10-10 Solar Masses], we derive a density of 3.4 +/- 0.9 g.cm-3 significantly different from the density of C-type (1) Ceres of 2.2 +/- 0.1 g.cm-3. Considering the spectral similarities of Pallas and Ceres at visible and near-infrared wavelengths, this may point to fundamental differences in the interior composition or structure of these two bodies. We define a planetocentric longitude system for Pallas, following IAU guidelines. We also present the first albedo maps of Pallas covering ~80% of the surface in K-band. These maps reveal features with diameters in the 70-180 km range and an albedo contrast of about 6% wrt the mean surface albedo.Comment: 16 pages, 8 figures, 6 table

    Interplay of quantum and classical fluctuations near quantum critical points

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    For a system near a quantum critical point (QCP), above its lower critical dimension dLd_L, there is in general a critical line of second order phase transitions that separates the broken symmetry phase at finite temperatures from the disordered phase. The phase transitions along this line are governed by thermal critical exponents that are different from those associated with the quantum critical point. We point out that, if the effective dimension of the QCP, deff=d+zd_{eff}=d+z (dd is the Euclidean dimension of the system and zz the dynamic quantum critical exponent) is above its upper critical dimension dCd_C, there is an intermingle of classical (thermal) and quantum critical fluctuations near the QCP. This is due to the breakdown of the generalized scaling relation ψ=νz\psi=\nu z between the shift exponent ψ\psi of the critical line and the crossover exponent νz\nu z, for d+z>dCd+z>d_C by a \textit{dangerous irrelevant interaction}. This phenomenon has clear experimental consequences, like the suppression of the amplitude of classical critical fluctuations near the line of finite temperature phase transitions as the critical temperature is reduced approaching the QCP.Comment: 10 pages, 6 figures, to be published in Brazilian Journal of Physic

    Effective Actions and Phase Fluctuations in d-wave Superconductors

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    We study effective actions for order parameter fluctuations at low temperature in layered d-wave superconductors such as the cuprates. The order parameter lives on the bonds of a square lattice and has two amplitude and two phase modes associated with it. The low frequency spectral weights for amplitude and relative phase fluctuations is determined and found to be subdominant to quasiparticle contributions. The Goldstone phase mode and its coupling to density fluctuations in charged systems is treated in a gauge-invariant manner. The Gaussian phase action is used to study both the cc-axis Josephson plasmon and the more conventional in-plane plasmon in the cuprates. We go beyond the Gaussian theory by deriving a coarse-grained quantum XY model, which incorporates important cutoff effects overlooked in previous studies. A variational analysis of this effective model shows that in the cuprates, quantum effects of phase fluctuations are important in reducing the zero temperature superfluid stiffness, but thermal effects are small for T<<TcT << T_c.Comment: Some numerical estimates corrected and figures changed. to appear in PRB, Sept.1 (2000

    Glycogen-rich Clear Cell Carcinoma of the Breast: A Comprehensive Review.

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    Glycogen-rich clear cell carcinoma (GRCC) is a very rare form of primary breast cancer (<0.1% of all breast cancers). It is characterized by the presence of neoplastic cells with a glycogen-abundant clear cytoplasm (the Periodic Acid Schiff-positive, diastase-sensitive). The expression of steroid receptors (estrogen and progesterone receptors) has been variably reported (35% to 100% of the cases), whereas most studies reported low human epidermal growth factor receptor 2 positivity in GRCC. High androgen receptor positivity without androgen receptor splice variant-7 was reported in one recent study. Although sparse, the preliminary theranostic data on GRCC indicate the potential of targeted treatments in selected cases (antiandrogen, PIK3CA, and immune checkpoint inhibitors). Because of its rarity, the prognosis for GRCC patients remains controversial. Herein, we comprehensively appraise the epidemiological, morphologic, molecular, and clinical characteristics of this rare mammary malignancy

    Awareness and use of intertrochanteric osteotomies in current clinical practice. An international survey

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    Current literature shows that intertrochanteric osteotomies can produce excellent results in selected hip disorders in specific groups of patients. However, it appears that this surgical option is considered an historical one that has no role to play in modern practice. In order to examine current awareness of and views on intertrochanteric osteotomies among international hip surgeons, an online survey was carried out. The survey consisted of a set of questions regarding current clinical practice and awareness of osteotomies. The second part of the survey consisted of five clinical cases and sought to elicit views on preoperative radiological investigations and preferred (surgical) treatments. The results of our survey showed that most of these experts believe that intertrochanteric osteotomies should still be performed in selected cases. Only 56% perform intertrochanteric osteotomies themselves and of those, only 11% perform more than five per year. The responses to the cases show that about 30–40% recommend intertrochanteric osteotomies in young symptomatic patients. This survey shows that the role of intertrochanteric osteotomies is declining in clinical practice

    Variation in CHI3LI in Relation to Type 2 Diabetes and Related Quantitative Traits

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    CHI3LI encoding the inflammatory glycoprotein YKL-40 is located on chromosome 1q32.1. YKL-40 is involved in inflammatory processes and patients with Type 2 Diabetes (T2D) have elevated circulating YKL-40 levels which correlate with their level of insulin resistance. Interestingly, it has been reported that rs10399931 (-329 G/A) of CHI3LI contributes to the inter-individual plasma YKL-40 levels in patients with sarcoidosis, and that rs4950928 (-131 C/G) is a susceptibility polymorphism for asthma and a decline in lung function. We hypothesized that single nucleotide polymorphisms (SNPs) or haplotypes thereof the CHI3LI locus might influence risk of T2D. The aim of the present study was to investigate the putative association between SNPs and haplotype blocks of CHI3LI and T2D and T2D related quantitative traits.Eleven SNPs of CHI3LI were genotyped in 6514 individuals from the Inter99 cohort and 2924 individuals from the outpatient clinic at Steno Diabetes Center. In cas-control studies a total of 2345 T2D patients and 5302 individuals with a normal glucose tolerance test were examined. We found no association between rs10399931 (OR, 0.98 (CI, 0.88-1.10), p = 0.76), rs4950928 (0.98 (0.87-1.10), p = 0.68) or any of the other SNPs with T2D. Similarly, we found no significant association between any of the 11 tgSNPs and T2D related quantitative traits, all p>0.14. None of the identified haplotype blocks of CHI3LI showed any association with T2D, all p>0.16.None of the examined SNPs or haplotype blocks of CHI3LI showed any association with T2D or T2D related quantitative traits. Estimates of insulin resistance and dysregulated glucose homeostasis in T2D do not seem to be accounted for by the examined variations of CHI3LI

    Extracorporeal cellular therapy (ELAD) in severe alcoholic hepatitis: A multinational, prospective, controlled, randomized trial.

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    Severe alcoholic hepatitis (sAH) is associated with a poor prognosis. There is no proven effective treatment for sAH, which is why early transplantation has been increasingly discussed. Hepatoblastoma-derived C3A cells express anti-inflammatory proteins and growth factors and were tested in an extracorporeal cellular therapy (ELAD) study to establish their effect on survival for subjects with sAH. Adults with sAH, bilirubin ≥8 mg/dL, Maddrey\u27s discriminant function ≥ 32, and Model for End-Stage Liver Disease (MELD) score ≤ 35 were randomized to receive standard of care (SOC) only or 3-5 days of continuous ELAD treatment plus SOC. After a minimum follow-up of 91 days, overall survival (OS) was assessed by using a Kaplan-Meier survival analysis. A total of 203 subjects were enrolled (96 ELAD and 107 SOC) at 40 sites worldwide. Comparison of baseline characteristics showed no significant differences between groups and within subgroups. There was no significant difference in serious adverse events between the 2 groups. In an analysis of the intent-to-treat population, there was no difference in OS (51.0% versus 49.5%). The study failed its primary and secondary end point in a population with sAH and with a MELD ranging from 18 to 35 and no upper age limit. In the prespecified analysis of subjects with MELD \u3c 28 (n = 120), ELAD was associated with a trend toward higher OS at 91 days (68.6% versus 53.6%; P = .08). Regression analysis identified high creatinine and international normalized ratio, but not bilirubin, as the MELD components predicting negative outcomes with ELAD. A new trial investigating a potential benefit of ELAD in younger subjects with sufficient renal function and less severe coagulopathy has been initiated. Liver Transplantation 24 380-393 2018 AASLD

    Synthesis and Characterization of Rutile TiO2Nanopowders Doped with Iron Ions

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    Titanium dioxide nanopowders doped with different amounts of Fe ions were prepared by coprecipitation method. Obtained materials were characterized by structural (XRD), morphological (TEM and SEM), optical (UV/vis reflection and photoluminescence, and Raman), and analytical techniques (XPS and ICP-OES). XRD analysis revealed rutile crystalline phase for doped and undoped titanium dioxide obtained in the same manner. Diameter of the particles was 5–7 nm. The presence of iron ions was confirmed by XPS and ICP-OES. Doping process moved absorption threshold of TiO2into visible spectrum range. Photocatalytic activity was also checked. Doped nanopowders showed normal and up-converted photoluminescence

    Expression analysis of carbohydrate antigens in ductal carcinoma in situ of the breast by lectin histochemistry

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    <p>Abstract</p> <p>Background</p> <p>The number of breast cancer patients diagnosed with ductal carcinoma <it>in situ </it>(DCIS) continues to grow. Laboratory and clinical data indicate that DCIS can progress to invasive disease. Carbohydrate-mediated cell-cell adhesion and tumor-stroma interaction play crucial roles in tumorigenesis and tumor aggressive behavior. Breast carcinogenesis may reflect quantitative as well as qualitative changes in oligosaccharide expression, which may provide a useful tool for early detection of breast cancer. Because tumor-associated carbohydrate antigens (TACA) are implicated in tumor invasion and metastasis, the purpose of this study was to assess the expression of selected TACA by lectin histochemistry on DCIS specimens from the archival breast cancer tissue array bank of the University of Arkansas for Medical Sciences.</p> <p>Methods</p> <p>For detection of TACA expression, specimens were stained with <it>Griffonia simplicifolia </it>lectin-I (GS-I) and <it>Vicia vilosa </it>agglutinin (VVA). We studied associations of lectin reactivity with established prognostic factors, such as tumor size, tumor nuclear grade, and expression of Her-2/neu, p53 mutant and estrogen and progesterone receptors.</p> <p>Results</p> <p>We observed that both lectins showed significant associations with nuclear grade of DCIS. DCIS specimens with nuclear grades II and III showed significantly more intense reactivity than DCIS cases with nuclear grade I to GS-1 (Mean-score chi-square = 17.60, DF = 2; <it>P </it>= 0.0002) and VVA (Mean-score chi-square = 15.72, DF = 2; <it>P </it>= 0.0004).</p> <p>Conclusion</p> <p>The results suggest that the expression of VVA- and GS-I-reactive carbohydrate antigens may contribute to forming higher grade DCIS and increase the recurrence risk.</p
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