Tunable Nonlocal Spin Control in a Coupled-Quantum Dot System

The effective interaction between magnetic impurities in metals that can lead to various magnetic ground states often competes with a tendency for electrons near impurities to screen the local moment (known as the Kondo effect). The simplest system exhibiting the richness of this competition, the two-impurity Kondo system, was realized experimentally in the form of two quantum dots coupled through an open conducting region. We demonstrate nonlocal spin control by suppressing and splitting Kondo resonances in one quantum dot by changing the electron number and coupling of the other dot. The results suggest an approach to nonlocal spin control that may be relevant to quantum information processing.

Subtrochanteric fractures. A review of treatment options

Subtrochanteric fractures of the femur were originally grouped with comminuted intertrochanteric fractures. However, they pose their own distinct management problems mainly due to biomechanical differences in stability and are now considered separately. There are several classification systems but the most widely accepted is the one proposed by Seinsheimer in 1978. Many different methods have been employed in the management of this group of fractures with varying rates of success. The management has altered as new implants have been developed to try to overcome the shortfalls of the existing implants. This study is a review of the literature and was carried out using Medline and the Cochrane Library to look at the management methods employed in the past and today. Most of the published articles are retrospective uncontrolled reports of the results of management and it is difficult to suggest management principles from them. The other main shortcoming is that, although there are several devices available on the market for the management of these fractures, most of the literature concerns one or two of them. The results reported examine union rates and failure of implants leading to reoperation. This is a crude outcome measure, and there is very little in the literature regarding patient function. In order to provide evidence-based advice on the best management options for these difficult fractures, future studies should be designed as randomized controlled trials and place more emphasis on studying patients' outcomes.

The human 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) gene cluster on chromosome 1p13 contains a presumptive pseudogene; 3 beta-HSD and CYP17 do not segregate with dominantly inherited hirsutism

Four hirsute females from a family exhibiting idiopathic dominant hirsutism were examined. Basal blood levels of delta 5 and delta 4 steroids were within the normal range, but ACTH stimulation led to increases in 17-hydroxypregnenolone and dehydroepiandrosterone that were significantly above control levels. Using polymorphic genetic markers, the genes for cytochrome P450c1717 encoded by CYP17, and the type I and II forms of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) were found not to segregate with hirsutism in this family, though a base substitution was detected in the 3' end of exon 1 of the gene for 3 beta-HSD type I in three of the four patients investigated. Analysis of PCR patients amplification products by denaturing gradient gel electrophoresis (DGGE) and sequencing revealed a novel homologue of exon 3 of 3 beta-HSD. DNA of one of the affected patients was used to create a genomic library in lambda gem 11 and clones containing the novel homologue were obtained and partially sequenced. The equivalent clone was obtained from a genomic library of an unrelated normal individual. The sequences of the clones from patient and control were identical and homologous to exons 2-4 of human 3 beta-HSD types I and II. No difference was found in the PCR primer sites that flanked the exons 3 homologue which led to its detection on DGGE gels. In both clones, stop codons and deletions were identified in the exon 4 homologue, leading to the deduction that the sequence comes from a pseudogene, which we call 3 beta-HSD psi 1. The pseudogene mapped to chromosome 1p13. It was concluded that dominantly inherited idiopathic hirsutism in this rare kindred was not due to deficiencies in 3 beta-HSD types I, II, or psi or of CYP17).