Infrared reflectivity spectra of single crystals of La2CuO4.

Infrared reflectivity spectra of a La2CuO4+x single crystal have been studied over a spectral range of 50"5500 cm-1. Anisotropy of the spectra has been observed, indicating a strong anisotropy of the high-frequency conductivity of the crystal. New lines have been found in the optical-phonon excitation spectra. A classification of lattice optical vibrations has been proposed. Spectral reconstruction has been observed in the phonon region of 370 and 445 cm-1 at T0=220±5 K, which correlates with the antiferromagnetic transition. © 1989 The American Physical Society

Raman scattering in single crystal La2CuO4

The results of a Raman scattering study of single crystal La CuO are reported. Three Ag symmetry modes are observed, rather than the two predicted by group theory. Mode assignments are discussed. © 1988. 2

Raman scattering in single crystal La2CuO4

The results of a Raman scattering study of single crystal La2CuO4 are reported. Three Ag symmetry modes are observed, rather than the two predicted by group theory. Mode assignments are discussed. © 1988

Resolving the dynamics of EEG generators by multichannel recordings

The voltage recorded over the cortex (ECoG) or over the scalp (EEG) is generated by currents derived from many sources called “generators”. Different patterns and amplitudes are observed in aroused, sleepy, epileptic or other brain states. Differences in amplitude are generally attributed to differences in synchrony among generators. The degree of EEG synchrony is measured by the correlation between electrodes placed over different cortical regions. We present a new way to quantitatively assess the degree of synchronization of these generators via multichannel recordings. We illustrate how situations where there are several groups of generators with different inter-group and intra-group synchronies can be analyzed. Finally, we present a way to identify the organization of groups exhibiting topographic organization. Although the model presented here is highly simplified, several methods are based on averaging activity over increasingly larger areas. These types of measurements may be applied as well to EEG and ECoG recordings

Specific activity of cyclin-dependent kinase I is a new potential predictor of tumour recurrence in stage II colon cancer

BACKGROUND: There are no established biomarkers to identify tumour recurrence in stage II colon cancer. As shown previously, the enzymatic activity of the cyclin-dependent kinases 1 and 2 (CDK1 and CDK2) predicts outcome in breast cancer. Therefore, we investigated whether CDK activity identifies tumour recurrence in colon cancer. METHODS: In all, 254 patients with completely resected (R0) UICC stage II colon cancer were analysed retrospectively from two independent cohorts from Munich (Germany) and Leiden (Netherlands). None of the patients received adjuvant treatment. Development of distant metastasis was observed in 27 patients (median follow-up: 86 months). Protein expression and activity of CDKs were measured on fresh-frozen tumour samples. RESULTS: Specific activity (SA) of CDK1 (CDK1SA), but not CDK2, significantly predicted distant metastasis (concordance index=0.69, 95% confidence interval (CI): 0.55–0.79, P=0.036). Cutoff derivation by maximum log-rank statistics yielded a threshold of CDK1SA at 11 (SA units, P=0.029). Accordingly, 59% of patients were classified as high-risk (CDK1SA ⩾11). Cox proportional hazard analysis revealed CDK1SA as independent prognostic variable (hazard ratio=6.2, 95% CI: 1.44–26.9, P=0.012). Moreover, CKD1SA was significantly elevated in microsatellite-stable tumours. CONCLUSION: Specific activity of CDK1 is a promising biomarker for metastasis risk in stage II colon cancer