Spherical functions on the de Sitter group

Matrix elements and spherical functions of irreducible representations of the de Sitter group are studied on the various homogeneous spaces of this group. It is shown that a universal covering of the de Sitter group gives rise to quaternion Euler angles. An explicit form of Casimir and Laplace-Beltrami operators on the homogeneous spaces is given. Different expressions of the matrix elements and spherical functions are given in terms of multiple hypergeometric functions both for finite-dimensional and unitary representations of the principal series of the de Sitter group.Comment: 40 page

Everolimus in patients with metastatic renal cell carcinoma previously treated with bevacizumab: a prospective multicenter study CRAD001LRU02T⃰

Everolimus is an orally administered inhibitor of the mammalian target of rapamycin (mTOR) recommended for patients with metastatic renal cell carcinoma (mRCC) who progressed on previous vascular endothelial growth factor (VEGF) receptor-tyrosine kinase inhibitor therapy. Efficacy of everolimus in patients who progressed on anti-VEGF monoclonal antibody bevacizumab is unknown. We did a multicenter prospective trial of everolimus in patients with mRCC whose disease had progressed on bevacizumab ± interferon alpha (IFN). Patients with clear-cell mRCC which had progressed on bevacizumab ± IFN received everolimus 10 mg once daily. The primary end point was the proportion of patients remaining progression-free for 56 days, and a two-stage Simon design was used, with 80 % power and an alpha risk of 5 %. This study is registered with ClinicalTrials.gov, number NCT02056587. From December 2011 to October 2013, a total of 37 patients (28 M, 9 F) were enrolled. Median age was 60.5 years (range 41-66), 11 % had Eastern Cooperative Oncology Group Performance Status (ECOG PS) > 2, and Memorial Sloan-Kettering Cancer Center (MSKCC) favorable/intermediate risk was 38/62 %. Five (14 %) patients had a confirmed partial response and 26 (70 %) patients had a stable disease. Median progression-free survival was 11.5 months (95 % CI, 8.8–14.2). Median overall survival was not reached. No grade 3 or 4 treatment-related toxicities were observed. The most common grade 2 adverse events were fatigue (19 %) and pneumonitis (8 %). Everolimus demonstrated a favorable toxicity profile and promising anti-tumor activity as a second-line therapy in metastatic renal cell carcinoma (RCC) patients previously treated with bevacizumab ± IFN

Strong vortex-antivortex fluctuations in the type II superconducting film

The small size vortex-antivortex pairs proliferation in type II superconducting film is considered for the wide interval of temperatures below Tc. The corresponding contribution to free energy is calculated. It is shown that these fluctuations give the main contribution to the heat capacity of the film both at low temperatures and in the vicinity of transition

Theory of the pseudogap in the elementary excitation spectrum of the normal phase of bilayer cuprates

Solutions of the integral equations for the pseudogap in the elementary excitation spectrum of current carriers in bilayer cuprates are found. In the general case, the pseudogap possesses s+id symmetry, where the s component is determined by the interaction of holes via the phonon field and the d component is due to the superexchange interaction of the copper spins and the Coulomb-repulsion screened holes. The s and d components exhibit different temperature dependences. This fact enabled us to explain the characteristic features of the temperature behavior of the normal-phase spin susceptibility of lightly doped cuprates, specifically, for the compound YBa2Cu4O8 in the entire temperature interval T>Tc. The wave-number dependence of the pseudogap agrees with the photoemission data for Bi2Sr2CaCu2O8+y. © 1997 American Institute of Physics

Dynamical charge susceptibility in layered cuprates: Beyond the conventional random-phase-approximation scheme

The analytical expression for a dynamical charge susceptibility in layered cuprates has been derived in the framework of a singlet-correlated band model beyond the random-phase-approximation (RPA) scheme. Our calculations performed near optimal doping regime show that there is a peak in the real part of the charge susceptibility χch(q, ω) at Q=(π,π) at strong enough intersite Coulomb repulsion. Together with strong maximum in the Im χch(Q, ω) at low frequencies, it confirms the formation of low-energy collective excitations or charge fluctuations. This justifies that these excitations are important and together with spin fluctuations can contribute to the Cooper pairing in layered cuprates. Analyzing the charge susceptibility with respect to the instability we obtain a new plasmon branch, ωq, along the Brillouin zone (BZ). In particular, we have found that it goes to zero around Q≈(π,π)

Magnitude of spin and charge density wave amplitudes in underdoped cuprates

Self-consistent calculation of spin (charge) density wave (S(C)DW) order parameters have been performed for bilayered cuprates on the basis of a singlet-correlated band model. Evolution of the Fermi surface in the strongly underdoped regime is described by a two-band approach. The smooth development of the pseudogap formation temperature from underdoped to overdoped states is explained and the Fourier amplitudes 〈sq〉 (spin) and 〈eq〉 (charge) modulations are calculated. We have found a maximum of the incommensurability for doping 0.09÷0.11 holes per copper site. © Springer-Verlag 2000

CDW scenario for pseudogap in normal state of bilayer cuprates

Using the model of the singlet-correlated band the temperature dependence of d-wave superconducting (SC) and charge density wave (CDW) gaps have been calculated. Temperature interval of SC and CDW coexistence strongly depends on the relation between superexchange and Coulomb parameters. At low temperature the superconductivity suppresses CDW. © 1999 Published by Elsevier Science B.V. All rights reserved

Gaussian superconducting fluctuations, thermal transport, and the Nernst effect

We calculate the contribution of superconducting fluctuations to thermal transport in the normal state, for low magnetic fields. We do so in the Gaussian approximation to their critical dynamics which is also the Aslamazov-Larkin approximation in the microscopics. Our results for the thermal conductivity tensor and the transverse thermoelectric response are new. The latter compare favorably with the data of Ong and collaborators on the Nernst effect in the cuprates.Comment: 4 pages, 1 figure; improved introduction, minor changes; published versio

Temperature dependence of the collective mode and its influence on the band splitting in bilayer cuprates

The recently observed bilayer splitting in high-T$_c$ cuprates is analyzed within a model where the charge carriers are coupled to a phenomenological bosonic spectrum which interpolates between the marginal Fermi liquid structure and collective mode type behavior as a function of temperature. We argue that the origin of the collective mode is probably associated with dynamic incommensurate charge density waves. Moreover it is shown that the resulting temperature dependence of the self-energy $\Sigma$ is in good agreement with $\Sigma$ as extracted from angle-resolved photoemission data.Comment: 6 pages, 4 figures, accepted for PR