7,581 research outputs found

    Vibrational properties of phonons in random binary alloys: An augmented space recursive technique in the k-representation

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    We present here an augmented space recursive technique in the k-representation which include diagonal, off-diagonal and the environmental disorder explicitly : an analytic, translationally invariant, multiple scattering theory for phonons in random binary alloys.We propose the augmented space recursion (ASR) as a computationally fast and accurate technique which will incorporate configuration fluctuations over a large local environment. We apply the formalism to Ni55Pd45Ni_{55}Pd_{45}, Ni_{88}Cr_12} and Ni50Pt50Ni_{50}Pt_{50} alloys which is not a random choice. Numerical results on spectral functions, coherent structure factors, dispersion curves and disordered induced FWHM's are presented. Finally the results are compared with the recent itinerant coherent potential approximation (ICPA) and also with experiments.Comment: 20 pages, LaTeX, 23 figure

    Numerical Study of Length Spectra and Low-lying Eigenvalue Spectra of Compact Hyperbolic 3-manifolds

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    In this paper, we numerically investigate the length spectra and the low-lying eigenvalue spectra of the Laplace-Beltrami operator for a large number of small compact(closed) hyperbolic (CH) 3-manifolds. The first non-zero eigenvalues have been successfully computed using the periodic orbit sum method, which are compared with various geometric quantities such as volume, diameter and length of the shortest periodic geodesic of the manifolds. The deviation of low-lying eigenvalue spectra of manifolds converging to a cusped hyperbolic manifold from the asymptotic distribution has been measured by ζ−\zeta- function and spectral distance.Comment: 19 pages, 18 EPS figures and 2 GIF figures (fig.10) Description of cusped manifolds in section 2 is correcte

    The correction of the littlest Higgs model to the Higgs production process e−γ→νeW−He^{-}\gamma\to \nu_{e}W^{-}H in e−γe^{-}\gamma collisions

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    The littlest Higgs model is the most economical one among various little Higgs models. In the context of the littlest Higgs(LH) model, we study the process e−γ→νeW−He^{-}\gamma\to \nu_{e}W^{-}H and calculate the contributions of the LH model to the cross section of this process. The results show that, in most of parameter spaces preferred by the electroweak precision data, the value of the relative correction is larger than 10%. Such correction to the process e−γ→νeW−He^{-}\gamma\to \nu_{e}W^{-}H is large enough to be detected via e−γe^{-}\gamma collisions in the future high energy linear e+e−e^{+}e^{-} collider(LCLC) experiment with the c.m energy s\sqrt{s}=500 GeV and a yearly integrated luminosity £=100fb−1\pounds=100fb^{-1}, which will give an ideal way to test the model.Comment: 13 pages, 4 figure

    Squark anti-squark pair production at the LHC: the electroweak contribution

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    We present the complete NLO electroweak contribution of O(αs2α)\mathcal{O}(\alpha^2_s \alpha) to the production of diagonal squark--anti-squark pairs in proton--proton collisions. Compared to the lowest-order O(αsα+α2)\mathcal{O}(\alpha_s\alpha + \alpha^2) electroweak terms, the NLO contributions are also significant. We discuss the LO and NLO electroweak effects in cross sections and distributions at the LHC for the production of squarks different from top squarks, in various supersymmetric benchmark scenarios.Comment: 38 pages, 21 figures. Replaced with the version published in JHE

    The littlest Higgs model and Higgs boson associated production with top quark pair at high energy linear e+e−e^{+}e^{-} collider

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    In the parameter space allowed by the electroweak precision measurement data, we consider the contributions of the new particles predicted by the littlest Higgs(LHLH) model to the Higgs boson associated production with top quark pair in the future high energy linear e+e−e^{+}e^{-} collider(ILCILC). We find that the contributions mainly come from the new gauge bosons ZHZ_{H} and BHB_{H}. For reasonable values of the free parameters, the absolute value of the relative correction parameter δσ/σSM\delta\sigma/\sigma^{SM} can be significanly large, which might be observed in the future ILCILC experiment with S=800GeV\sqrt{S}=800GeV.Comment: latex files, 13 pages, 3 figure

    High STEAP1 expression is associated with improved outcome of Ewing's sarcoma patients

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    Background Ewing's sarcoma (ES) is the second most common bone or soft-tissue sarcoma in childhood and adolescence and features a high propensity to metastasize. The six-transmembrane epithelial antigen of the prostate 1 (STEAP1) is a membrane-bound mesenchymal stem cell marker highly expressed in ES. Here, we investigated the role of STEAP1 as an immunohistological marker for outcome prediction in patients with ES. Patients and methods Membranous STEAP1 immunoreactivity was analyzed using immunohistochemistry in 114 primary pre-chemotherapy ES of patients diagnosed from 1983 to 2010 and compared with clinical parameters and patient outcome. Median follow-up was 3.85 years (range 0.43-17.51). Results A total of 62.3% of the ES samples displayed detectable STEAP1 expression with predominant localization of the protein at the plasma membrane. High membranous STEAP1 immunoreactivity was found in 53.5%, which correlated with better overall survival (P=0.021). Accordingly, no or low membranous STEAP1 expression was identified as an independent risk factor in multivariate analysis (hazard ratio 2.65, P=0.036). Conclusion High membranous STEAP1 expression predicts improved outcome and may help to define a specific subgroup of ES patients, who might benefit from adapted therapy regimen

    On the Whitehead spectrum of the circle

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    The seminal work of Waldhausen, Farrell and Jones, Igusa, and Weiss and Williams shows that the homotopy groups in low degrees of the space of homeomorphisms of a closed Riemannian manifold of negative sectional curvature can be expressed as a functor of the fundamental group of the manifold. To determine this functor, however, it remains to determine the homotopy groups of the topological Whitehead spectrum of the circle. The cyclotomic trace of B okstedt, Hsiang, and Madsen and a theorem of Dundas, in turn, lead to an expression for these homotopy groups in terms of the equivariant homotopy groups of the homotopy fiber of the map from the topological Hochschild T-spectrum of the sphere spectrum to that of the ring of integers induced by the Hurewicz map. We evaluate the latter homotopy groups, and hence, the homotopy groups of the topological Whitehead spectrum of the circle in low degrees. The result extends earlier work by Anderson and Hsiang and by Igusa and complements recent work by Grunewald, Klein, and Macko.Comment: 52 page

    Prolonged fixed dose rate infusion of gemcitabine with autologous haemopoietic support in advanced pancreatic adenocarcinoma

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    This study aimed to define the maximum-tolerated dose (MTD) of fixed dose rate (FDR) of gemcitabine (2′-2′-difluorodeoxycitidine) infusion with circulating haemopoietic progenitor support and to evaluate the activity of the treatment. Secondary end points were pharmacokinetic of gemcitabine and difluorodeoxyuridina (dFdU) measured at first course and the activity andexpression profile of cytidine deaminase (CdA) on circulating mononuclear cells. Patients with advanced pancreatic carcinoma received escalating dose of gemcitabine 10 mg m−2 min−1 every 2 weeks with circulating haemopoietic progenitor support. First dose level was 3000 mg m−2 and the doses were increased by 500 mg m−2 until MTD. In all, 23 patients were enrolled. Toxicities were mild or moderate; the only patient treated at 7000 mg m−2 died because of toxicity; therefore; the MTD was established at 6500 mg m−2. The overall response rate was 22.2%. The AUC of gemcitabine showed a dose-dependent increase, while the AUC of dFdU reached a plateau at 4500 mg m−2. A significant relationship was found between the AUC of dFdU and CdA expression and activity (P<0.05). Moreover, progression rate and survival were significantly related to CdA expression and activity levels. The activity of high-dose gemcitabine is not superior to that reported with less intensive FDR schedules. The predictive role of CdA expression and activity on outcome deserves further investigation

    CD4\u3csup\u3e+\u3c/sup\u3e T cells in the lungs of acute sarcoidosis patients recognize an Aspergillus nidulans epitope

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    Löfgren’s syndrome (LS) is an acute form of sarcoidosis characterized by a genetic association with HLA-DRB1*03 (HLA-DR3) and an accumulation of CD4+ T cells of unknown specificity in the bronchoalveolar lavage (BAL). Here, we screened related LS-specific TCRs for antigen specificity and identified a peptide derived from NAD-dependent histone deacetylase hst4 (NDPD) of Aspergillus nidulans that stimulated these CD4+ T cells in an HLA-DR3–restricted manner. Using ELISPOT analysis, a greater number of IFN-γ– and IL-2–secreting T cells in the BAL of DR3+ LS subjects compared with DR3+ control subjects was observed in response to the NDPD peptide. Finally, increased IgG antibody responses to A. nidulans NDPD were detected in the serum of DR3+ LS subjects. Thus, our findings identify a ligand for CD4+ T cells derived from the lungs of LS patients and suggest a role of A. nidulans in the etiology of LS
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