Raman-scattering detection of nearly degenerate s-wave and d-wave pairing channels in iron-based Ba0.6K0.4Fe2As2 and Rb0.8Fe1.6Se2 superconductors

We show that electronic Raman scattering affords a window into the essential properties of the pairing potential V(k,k') of iron-based superconductors. In Ba0.6K0.4Fe2As2 we observe band dependent energy gaps along with excitonic Bardasis-Schrieffer modes characterizing, respectively, the dominant and subdominant pairing channel. The d(x(2)-y(2)) symmetry of all excitons allows us to identify the subdominant channel to originate from the interaction between the electron bands. Consequently, the dominant channel driving superconductivity results from the interaction between the electron and hole bands and has the full lattice symmetry. The results in Rb(0.8)Fe(1.6)Se(2) along with earlier ones in Ba(Fe(0.939)Co(0.061))(2)As(2) highlight the influence of the Fermi surface topology on the pairing interactions.

Abstract P4-13-11: Prognostic factors in young breast cancer patients over time – a 40 year longitudinal analysis

Background: In younger patients (pts) breast cancer (BC) is associated with a worse prognosis compared to older pts. Only few data are available presenting the development of prognostic factors regarding a period of several decades. This 40 year (y) longitudinal comparison of the main prognostic factors was performed to investigate differences in younger women with primary BC in contrast to older women over time.

Patients and Methods: In this retrospective analysis a consecutive pts cohort of 4010 pts was analyzed. Pts were documented and treated for primary invasive breast cancer between 1963 and 2003 at two University Hospitals in Germany. To be eligible, pts were required to have identified tumor characteristics, including TNM-status. Pts with carcinoma in situ or distant metastases were excluded. The cohort was divided in two age groups, ≤40y and >40y. Furthermore to reveal trends and changes over the duration of 41 years the period of analysis was split into 3 time frames: 1963–1976, 1977–1989 and 1990–2003. We analyzed the main prognostic factors for BC including tumor size, grading, nodal status and HR-status in longitudinal comparison regarding the three time frames, respectively. During 1963–77 HR-status was determined in just 12.6% of pts. Thus, this time frame was excluded in the analysis of HR-status.

Results: In 41 yrs, 747 (18.6%) pts were treated between 1963–76, 1722 pts (42.9%) in 1977–89 and 1541 pts (38.4%) in 1990–2003. Overall 358 pts were ≤40y and 3652 pts were over the age of 40.

A significant reduction of tumor size (metric assessment) at primary diagnosis was observed for both age groups (pts≤40y: p = 0.012; pts>40y: p < 0.0001) with no difference between the time frames, respectively (1963–76: p = 0.289; 1977–89: p = 0.647; 1990–2003: p = 0.937).

The number of node-positive pts significantly decreased in pts >40 y (p = 0.001) whereas no difference could be seen in pts aged ≤40 y (p = 0.991).

In both age groups the number of G2/3 tumors increased over the yrs (pts≤40y: p = 0.001; pts>40y: p < 0.0001). Between 1963–76 more G1-tumors were diagnosed in younger pts (p = 0.041) whereas in the two following periods significantly more G2/3 tumors (p = 0.001; p = 0.002) were observed in this group.

In young pts, 54.2% were HR-negative in 1977–89 and 47.6% in 1990–2003 (p = 0.323). In pts >40y 38.4% and 21.7% were HR-negative, respectively (p < 0.0001). Comparing the age groups, significantly more pts were HR-negative in the young patient group (p = 0.001 (1977–89) and p < 0.0001 (1990–2003)).

Conclusions: Concerning the large period of 40yrs, technical improvement and increasing awareness for BC are reasons for decreasing tumor size at the time of primary diagnosis. However, the rate of node-positive pts in the young patient group remained stable. Furthermore, the high percentage of HR-negative pts and the increasing number of pts with unfavorable tumor grade demonstrate more aggressive tumor types in younger pts. These data confirm the need to improve screening tools to early identify young women with the risk to develop breast cancer, and for personalized treatment approaches in these patients.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-13-11.

An electron-boson glue function derived from electronic Raman scattering

Raman scattering cross sections depend on photon polarization. In the cuprates, nodal and antinodal directions are weighted more strongly in B(2g) and B(1g) symmetries, respectively. On the other hand, in angle-resolved photoemission spectroscopy (ARPES), electronic properties are measured along well-defined directions in momentum space rather than their weighted averages being taken. In contrast, the optical conductivity involves a momentum average over the entire Brillouin zone. Newly measured Raman response data on high-quality Bi(2)Sr(2)CaCu(2)O(8 + δ) single crystals up to high energies have been inverted using a modified maximum entropy inversion technique to extract from B(1g) and B(2g) Raman data corresponding electron-boson spectral densities (glue), and these are compared to the results obtained with known ARPES and optical inversions. We find that the B(2g) spectrum agrees qualitatively with nodal direction ARPES while the B(1g) results look more like the optical spectrum. A large peak around 30-40 meV in B(1g) and a much less prominent one in B(2g) are taken as support for the importance of (π, π) scattering at this frequency.