10 research outputs found
Guiding center picture of magnetoresistance oscillations in rectangular superlattices
We calculate the magneto-resistivities of a two-dimensional electron gas
subjected to a lateral superlattice (LSL) of rectangular symmetry within the
guiding-center picture, which approximates the classical electron motion as a
rapid cyclotron motion around a slowly drifting guiding center. We explicitly
evaluate the velocity auto-correlation function along the trajectories of the
guiding centers, which are equipotentials of a magnetic-field dependent
effective LSL potential. The existence of closed equipotentials may lead to a
suppression of the commensurability oscillations, if the mean free path and the
LSL modulation potential are large enough. We present numerical and analytical
results for this suppression, which allow, in contrast to previous quantum
arguments, a classical explanation of similar suppression effects observed
experimentally on square-symmetric LSL. Furthermore, for rectangular LSLs of
lower symmetry they lead us to predict a strongly anisotropic resistance
tensor, with high- and low-resistance directions which can be interchanged by
tuning the externally applied magnetic field.Comment: 12 pages, 9 figure
An uncommon, unilateral motor variation of the intercostobrachial nerve
The intercostobrachial nerve (ICBN) is commonly defined as a purely sensory nerve supplying the skin of the lateral chest wall, axilla, and medial arm. However, numerous branching patterns and distributions, including motor, have been reported. This report describes an uncommon variant of the right ICBN observed in both an 86-year-old white female cadaver and a 77-year-old white male cadaver. In both cases the ICBN presented with an additional muscular branch, termed the “medial pectoral branch”, piercing and therefore innervating the pectoralis major and minor muscles. Clinically, the ICBN is relevant during surgical access to the axilla and can result in sensory deficits (persistent pain/loss of sensory function) to this region following injury. However, damage to the variation observed in these cadavers may result in additional partial motor loss to pectoralis major and minor.http://www.elsevier.com/journals/morphologie/1286-0115hj2022Anatom
Nkx6.1 controls migration and axon pathfinding of cranial branchio-motoneurons
As many studies have focused on the mechanisms of motoneuron specification, little is known about the factors that control the subsequent development of postmitotic motoneurons. Previously, we showed that the transcription factor Nkx6.1 is required for the early specification of somatic motoneuron progenitors in the spinal cord. Our present analysis of hindbrain motoneuron development in Nkx6.1-deficient mouse embryos reveals that the early specification of branchio-motoneurons is independent of Nkx6.1 function, but that it is required for their subsequent development. In Nkx6.1 mutant mice, we observed defects in the migration, as well as in the axon projections of branchio-motoneurons. A detailed analysis of the migratory defect in facial branchio-motoneurons reveals ectopic expression of the cell surface receptors Ret and Unc5h3 in premigratory neurons, but no changes in the rhombomeric environment. Taken together, our findings demonstrate a requirement for Nkx6.1 in the development of postmitotic motoneurons, and suggest a cell-autonomous function in the control of branchio-motoneuron migration
CONCENTRATION AND DISTRIBUTION OF ELEMENTS IN NORMAL AND TUMOR TISSUE OF THE RAT ANALYZED BY THE HAMBURG PROTON MICROPROBE
HPLC analysis in drug level monitoring of K027
HPLC monitoring of pharmacokinetics was done in two body compartments of rats following intramuscular treatments with three different doses of K027, a bispyridinium mono-aldoxime type of antidotes to organoposphate intoxicated subjects. Reversed-phase HPLC separation with electrochemical detections was done to monitor the onset, the maximum level, and offset in K027 concentration. Serum level of K027 showed a fast onset, independently from the doses of K027. Drug level in brain was showing an essentially delayed kinetics