Stripe formation: A quantum critical point for cuprate superconductors

We discuss the effects of a quantum critical point located nearby optimum doping and related to local charge segregation (stripe phase). The fluctuations in the critical region produce at the same time a strong pairing mechanism and a non-Fermi liquid behavior in the normal phase above the superconducting critical temperature. Superconductivity is a stabilizing mechanism against charge ordering, i.e. the incommensurate charge density wave quantum critical point is unstable with respect to superconductivity. A complete scenario for the cuprates is presented.Comment: Proceedings of the Cape Cod Conference on "Spectroscopies in Novel Superconductors, SNS 97", to appear on J. Phys. and Chem. of Solid

Permanence of the information given during oncogenetic counseling to persons at familial risk of breast/ovarian and/or colon cancer

How long counselees retain the information given during their genetic consultation is of major importance. To address this issue, we conducted a survey among the 3500 families that have been offered genetic counseling at our Center since 1988. In August 2007, we mailed a questionnaire to a representative subset of 579 persons belonging to breast/ovarian or colon cancer families seen in the last 10 years, either carrying an identified mutation or not. Targeted topics included the meaning of hereditary predisposition, the medical prevention related to the familial risk, the steps to undertake for a new family member to enter the genetic testing program and general knowledge of hereditary predisposition to cancer. A total of 91 randomized non-respondents were sent a second, more inciting letter, in order to assess any non-response bias. Overall, 337 questionnaires were collected: response rate was 58%. Standardized average knowledge was 7.28±1.52 of 10. Scores were lowest concerning medical prevention. The level of knowledge decreased with age (P<10−6), but increased with educational level (P<10−5) and mutation status (P=0.01). Surprisingly, no erosion of patients' knowledge over the time was observed (P=0.41). Among persons at hereditary risk of colon cancer, the level of knowledge tended to improve with time, in contrast to the breast/ovarian group (P=0.017). Among persons with a familial risk of breast/ovarian or colon cancer, a renewal of oncogenetic counseling does not seem necessary to maintain the level of specific knowledge. Measures to help patients follow their medical prevention, as organizing or checking their medical examinations, seem indicated

Enhancement of the spin susceptibility in disordered interacting electrons and the metal-insulator transition

The response of a disordered interacting electron gas to a time and spatially varying magnetic field is discussed. Local spin conservation leads to a generalized Ward identity, which together with global spin conservation implies that the dynamic magnetic susceptibility (q,) must obey a simple diffusive form. The same identity, when combined with the general perturbative structure of (q,), also relates the renormalization of static susceptibility st and the spin diffusion constant Ds to the renormalization of the charge diffusion constant and the Fermi-liquid interaction amplitudes. These relations are shown to be consistent with perturbations to first order in t {=1/[(2)2N0D]} but only after nontrivial cancellations. Thus the Ward identity allows both easy derivation of (q,) from the renormalized theory and a consistency check on the scaling equations. By using the renormalization-group equations for these parameters, it is shown that there is strong enhancement of st and decrease in Ds with lowering temperature. The significance of this with respect to the metal-insulator transition is discussed. \ua9 1986 The American Physical Society