Anomalous-filling-factor-dependent nuclear-spin polarization in a 2D electron system.

Spin-related electronic phase transitions in the fractional quantum Hall regime are accompanied by a large change in resistance. Combined with their sensitivity to spin orientation of nuclei residing in the same plane as the 2D electrons, they offer a convenient electrical probe to carry out nuclear magnetometry. Despite conditions which should allow both electronic and nuclear-spin subsystems to approach thermodynamic equilibrium, we uncover for the nuclei a remarkable and strongly electronic filling-factor-dependent deviation from the anticipated thermal nuclear-spin polarization.

Gate-voltage control of spin interactions between electrons and nuclei in a semiconductor.

Semiconductors are ubiquitous in device electronics, because their charge distributions can be conveniently manipulated with voltages to perform logic operations. Achieving a similar level of control over the spin degrees of freedom, either from electrons or nuclei, could provide intriguing prospects for both information processing and the study of fundamental solid-state physics issues. Here we report procedures that carry out the controlled transfer of spin angular momentum between electrons-confined to two dimensions and subjected to a perpendicular magnetic field-and the nuclei of the host semiconductor, using gate voltages only. We show that the spin transfer rate can be enhanced near a ferromagnetic ground state of the electron system, and that the induced nuclear spin polarization can be subsequently stored and 'read out'. These techniques can also be combined into a spectroscopic tool to detect the low-energy collective excitations in the electron system that promote the spin transfer. The existence of such excitations is contingent on appropriate electron-electron correlations, and these can be tuned by changing, for example, the electron density via a gate voltage.

Ising ferromagnetism and domain morphology in the fractional quantum Hall regime.

The density driven quantum phase transition between the unpolarized and fully spin polarized nu = 2/3 fractional quantum Hall state is accompanied by hysteresis in accord with 2D Ising ferromagnetism and domain formation. The temporal behavior is reminiscent of the Barkhausen and time-logarithmic magnetic after-effects ubiquitous in familiar ferromagnets. It too suggests domain morphology and, in conjunction with NMR, intricate domain dynamics, which is partly mediated by the contact hyperfine interaction with nuclear spins of the host semiconductor.

Quantum interference in artificial band structures.

Magnetotransport experiments on two-dimensional electron systems with an atomically precise, one-dimensional potential modulation reveal striking quantum interference oscillations. Within a semiclassical framework, they are recognized either as self-interference along closed orbits, many of them rendered possible by magnetic breakdown between Fermi contour segments of the artificial band structure, or as interference-enhanced backscattering. The known commensurability oscillations appear as a special case of the latter mechanism.

Effectiveness of in-patient rehabilitation for sub-chronic and chronic low back pain by an integrative group treatment program (Swiss Multicentre Study).

In this multicentre intervention study, we compared an integrated group treatment program which combines psychological and education methods into a more active training approach, with the traditional individual approach of physiotherapy and physical procedures for sub-chronic and chronic low back pain. Our 411 patients had a 4-week inpatient treatment: 243 patients in an experimental program and 168 in a traditional program. Outcomes of 283 patients were assessed 3 months and 1 year after entry. The dropout rate was 31.1%. Both conditions demonstrated favourable initial effects on functional and psychological parameters, but the integrated approach showed better long-term results for work rehabilitation than the traditional approach. The most successful patients (n = 58) were younger and had a higher educational level in comparison to the unsuccessful subgroup (n = 71). The main conclusion is that an integrated approach promoting self control and behaviour change through educational measures achieves better long-term results than the traditional individual physiotherapy approach.

[Congenital melanotic tumors]. / Der kongenitale melanotische Tumor. Ein Beitrag zur Klinik, Pathogenese und Dignität anhand von 2 Fallbeobachtungen.

Congenital melanotic tumors are among the very rare tumors of early childhood. Their histogenesis and biological significance are still controversial today. The ideas of an odontogenic origin and of a neuroectodermal pathogenesis of these tumors range among the most frequently advocated hypotheses. Until about 1970 this type of tumor was almost always referred to as benign. Meanwhile there has been a change in the assessment of the character of congenital melanotic tumors. Above all, this is due to the fact that malignant cases have been repeatedly reported since 1970. Apart from an extensive review of the literature, 2 own cases are described which were treated surgically. The histological evaluation of the tumor material supports the assumption that these tumors are of odontogenic origin.

[Problems of tongue neoplasms in the light of personal observations]. / Zur Problematik des Zungenkarzinoms an Hand eigener Beobachtungen.

Due to unfavourable local and general conditions, the treatment of carcinoma of the tongue still yields unsatisfactory results. The authors ascertained that 101 patients with carcinoma of the tongue (68 males and 37 females), having an average age of 65.2 years, had been treated at their clinic within a period of 27 years (1948--1974). Only 21% of them survived five years. In this connexion, certain questions, which are essential in the authors' opinion, are discussed. Furthermore, the patients are subdivided with regard to different aspects.

[Topical treatment of maxillary sinusitis. Preliminary report]. / Ein Beitrag zur lokalen Behandlung der Kieferhöhlenentzündung Vorläufige Mitteilung

The representation of fundamental ideas is followed by the description of a new instillation preparation for the local treatment of sinusitis. The sterile filling material contains chloramphenicol, sulphanilamide and prednisolone in an organic, absorbable carrier substance based on gelatin. The indication, the technique of application and the results obtained up to now are mentioned. An average of 2.4 instillations was sufficient to achieve healing in 78.5% of the patients. Spontaneous closure of a great perforation occurred in some cases. It is emphasized that the surgical intervention nevertheless remains an integral part of sinusitis therapy and that the results obtained up to now should be corroborated by a greater number of cases and additional investigations.

[An interesting case]. / Der interessante Fall

A rare observation on a 57-year-old female patient serves to emphasize that striking findings may also occur in the orofacial region. In the present case, the patient was afflicted with a tubular cystadenoma of the oral mucosa, extending from 22 to 24. In this connection, the authors briefly deal with the epidemiology, clinic and morphology of these tumours.