1,046 research outputs found

    Algorithms to Evaluate Multiple Sums for Loop Computations

    Full text link
    We present algorithms to evaluate two types of multiple sums, which appear in higher-order loop computations. We consider expansions of a generalized hypergeometric-type sums, \sum_{n_1,...,n_N} [Gamma(a1.n+c1) Gamma(a2.n}+c2) ... Gamma(aM.n+cM)] / [Gamma(b1.n+d1) Gamma(b2.n+d2) ... Gamma(bM.n+dM)] x1^n1...xN^nN with ai.n=j=1Naijnjai.n=\sum_{j=1}^N a_{ij}nj, etc., in a small parameter epsilon around rational values of ci,di's. Type I sum corresponds to the case where, in the limit epsilon -> 0, the summand reduces to a rational function of nj's times x1^n1...xN^nN; ci,di's can depend on an external integer index. Type II sum is a double sum (N=2), where ci,di's are half-integers or integers as epsilon -> 0 and xi=1; we consider some specific cases where at most six Gamma functions remain in the limit epsilon -> 0. The algorithms enable evaluations of arbitrary expansion coefficients in epsilon in terms of Z-sums and multiple polylogarithms (generalized multiple zeta values). We also present applications of these algorithms. In particular, Type I sums can be used to generate a new class of relations among generalized multiple zeta values. We provide a Mathematica package, in which these algorithms are implemented.Comment: 30 pages, 2 figures; address of Mathematica package in Sec.6; version to appear in J.Math.Phy

    Significance of myocardial tenascin-C expression in left ventricular remodelling and long-term outcome in patients with dilated cardiomyopathy

    Get PDF
    Aim Dilated cardiomyopathy (DCM) has a variety of causes, and no useful approach to predict left ventricular (LV) remodelling and long-term outcome has yet been established. Myocardial tenascin-C (TNC) is known to appear under pathological conditions, possibly to regulate cardiac remodelling. The aim of this study was to clarify the significance of myocardial TNC expression in LV remodelling and the long-term outcome in DCM. Methods and results One hundred and twenty-three consecutive DCM patients who underwent endomyocardial biopsy for initial diagnosis were studied. Expression of TNC in biopsy sections was analysed immunohistochemically to quantify the ratio of the TNC-positive area to the whole myocardial tissue area (TNC area). Clinical parameters associated with TNC area were investigated. The patients were divided into two groups based on receiver operating characteristic analysis of TNC area to predict death: high TNC group with TNC area ≥2.3% (22 patients) and low TNC group with TNC area <2.3% (101 patients). High TNC was associated with diabetes mellitus. Comparing echocardiographic findings between before and 9 months after endomyocardial biopsy, the low TNC group was associated with decreased LV end-diastolic diameter and increased LV ejection fraction, whereas the high TNC group was not. Survival analysis revealed a worse outcome in the high TNC group than in the low TNC group (P < 0.001). Multivariable Cox regression analysis revealed that TNC area was independently associated with poor outcome (HR = 1.347, P = 0.032). Conclusions Increased myocardial TNC expression was associated with worse LV remodeling and long-term outcome in DCM

    Orbital Degeneracy and Peierls Instability in Triangular Lattice Superconductor Ir1x_{1-x}Ptx_xTe2_2

    Full text link
    We have studied electronic structure of triangular lattice Ir1x_{1-x}Ptx_xTe2_2 superconductor using photoemission spectroscopy and model calculations. Ir 4f4f core-level photoemission spectra show that Ir 5d5d t2gt_{2g} charge modulation established in the low temperature phase of IrTe2_2 is suppressed by Pt doping. This observation indicates that the suppression of charge modulation is related to the emergence of superconductivity. Valence-band photoemission spectra of IrTe2_2 suggest that the Ir 5d5d charge modulation is accompanied by Ir 5d5d orbital reconstruction. Based on the photoemission results and model calculations, we argue that the orbitally-induced Peierls effect governs the charge and orbital instability in the Ir1x_{1-x}Ptx_xTe2_2.Comment: 5 pages,4 figure

    Violation of Casimir Scaling for Static QCD Potential at Three-loop Order

    Full text link
    We compute the full O(αs4){\cal O}(\alpha_s^4) and O(αs4logαs){\cal O}(\alpha_s^4\log\alpha_s) corrections to the potential VR(r)V_R(r) between the static color sources, where VR(r)V_R(r) is defined from the Wilson loop in a general representation RR of a general gauge group GG. We find a violation of the Casimir scaling of the potential, for the first time, at O(αs4){\cal O}(\alpha_s^4). The effect of the Casimir scaling violation is predicted to reduce the tangent of VR(r)/CRV_R(r)/C_R proportionally to specific color factors dependent on RR. We study the sizes of the Casimir scaling violation for various RR's in the case G=SU(3)G=SU(3). We find that they are well within the present bounds from lattice calculations, in the distance region where both perturbative and lattice computations of VR(r)V_R(r) are valid. We also discuss how to test the Casimir scaling violating effect.Comment: 20 pages, 7 figures, v2: a typo in eq.(13) correcte

    Relationship Between Percutaneous Transhepatic Cholangioscopy Findings and Pattern of Carcinomatous Spread in the Bile Duct

    Get PDF
    To clarify the relationship between percutaneous transhepatic cholangioscopic findings such as papillogranular surface and vascular dilation, which are reportedly characteristic of carcinoma, and the pattern of spread for bile duct carcinomas, we compared endoscopic photographs with histological features of biopsy specimens in 57 regions of specimens from 35 patients with malignant stenosis of the bile duct. Regions with a papillogranular surface were associated with noninvasive mucosal carcinomas and papillary proliferation of superficial epithelia significantly more often than regions without such a surface (P<0.0001). The sensitivity and specificity of the papillogranular surface to noninvasive mucosal carcinoma was 79 and 95%, respectively, that of papillary proliferation of superficial epithelia was 100 and 98%, respectively. Regions with vascular dilation were associated with invasive carcinoma significantly more often than regions without vascular dilation (P<0.0001). The sensitivity and specificity of vascular dilation to invasive carcinoma were 90 and 86%, respectively. Results indicate that a papillogranular surface is related to noninvasive mucosal carcinomas while vascular dilation is related to invasive carcinomas. However, a papillogranular surface was even more closely related to papillary proliferation of superficial epithelia
    corecore