Pulsed nuclear magnetic resonance of potassium (39K) of whole body live and dead newborn mice. Double oscillation frequencies in T1 decay curves.

Pulsed nuclear magnetic resonance relaxation curves (T2 and T1) of potassium (39K) have been measured in detail on whole body newborn mice when alive, and on the same mice after death. The T2 curves are simple exponential with respect to time, but are shorter than for 39K in simple solutions. The T1 curves are not exponential decays, but show large oscillations that may be described approximately as the sum of two separate sine waves of different frequencies. Large T1 oscillations of complex waveform were previously observed by us with 39K in cancer tissues. Gyroscopic motion of adsorbed magnetoelectric dipoles is proposed as a possible physical mechanism accounting for the experimental observations.     

Solid state theory of competitive diffusion of associated Na+ and K+ in cells by free cation and vacancy (hole) mechanisms, with application to nerve

If, as recent evidence indicates, most cell potassium is associated with macromolecular fixed charge, then diffusion of potassium ions in cells might occur by (1) diffusion of the small fraction of free potassium in cell water (analogous to electrons in the conduction band of a semiconductor) or by (2) diffusion of vacancies on association sites (analogous to holes in a semiconductor). Derivations of the Fick first law of diffusion predict that partial substitution of sodium for potassium in the cell produces opposite effects on the effective diffusion constant of potassium for those mechanisms. Application of that substitution to nerve data suggests that rubidium ions diffuse by a free cation result when the nerve is clamped at its resting potential, but by a vacancy mechanism when the nerve is clamped at zero voltage.     

Pre-processing Agilent microarray data

Background  

Pre-processing methods for two-sample long oligonucleotide arrays, specifically the Agilent technology, have not been extensively studied. The goal of this study is to quantify some of the sources of error that affect measurement of expression using Agilent arrays and to compare Agilent's Feature Extraction software with pre-processing methods that have become the standard for normalization of cDNA arrays. These include log transformation followed by loess normalization with or without background subtraction and often a between array scale normalization procedure. The larger goal is to define best study design and pre-processing practices for Agilent arrays, and we offer some suggestions.     

Postgraduate training for overseas doctors in Britain.

Foreign doctors, other than those from the European Economic Area, who want to train in Britain have to satisfy registration and immigration requirements before they can take up a post. The General Medical Council administers the registration regulations. These are quite separate from the immigration formalities, which are handled by the Home Office. The rules on both are complicated, and doctors should seek advice early to ensure that unnecessary difficulties do not add to the inevitable stresses associated with moving to a new country and working in a strange system.