Effects of exercise on circadian rhythms and mobility in aging Drosophila melanogaster.

Daily life functions such as sleep and feeding oscillate with circa 24 h period due to endogenous circadian rhythms generated by circadian clocks. Genetic or environmental disruption of circadian rhythms is associated with various aging-related phenotypes. Circadian rhythms decay during normal aging, and there is a need to explore strategies that could avert age-related changes in the circadian system.

Interlayer coupling in EuS/SrS, EuS/PbSe and EuS/PbTe magnetic semiconductor superlattices.

Neutron reflectivity studies of EuS/SrS, EuS/PbSe and EuS/PbTe all-semiconductor superlattices were carried out in a search for exchange interlayer coupling. A relatively weak antiferromagnetic coupling was found in EuS/SrS and EuS/PbSe systems but no interlayer coupling was detected in EuS/PbTe superlattices. In EuS/SrS, where the SrS spacer is an insulator (E(g)≈4 eV), a very weak and short range interlayer coupling is in agreement with the earlier theoretical predictions that the interlayer coupling strength in EuS-based magnetic semiconductor superlattices depends strongly on the energy gap of the nonmagnetic layer and should decrease with an increase of the energy gap of the spacer material.

Probing hole-induced ferromagnetic exchange in magnetic semiconductors by inelastic neutron scattering.

The effect of hole doping on the exchange coupling of the nearest neighbor (NN) Mn pairs in Zn(1-x)MnxTe is probed by inelastic neutron scattering. The difference in the NN exchange energy DeltaJ1 in the presence and in the absence of the holes is determined. The obtained value of DeltaJ1 is in good agreement with the predictions of the Zener/RKKY model, even on the insulator side of the metal-insulator transition.