Heading direction with respect to a reference point modulates place-cell activity.

The tuning of neurons in area CA1 of the hippocampus emerges through a combination of non-spatial input from different sensory modalities and spatial information about the animal's position and heading direction relative to the spatial enclosure being navigated. The positional modulation of CA1 neuronal responses has been widely studied (e.g. place tuning), but less is known about the modulation of these neurons by heading direction. Here, utilizing electrophysiological recordings from CA1 pyramidal cells in freely moving mice, we report that a majority of neural responses are modulated by the heading-direction of the animal relative to a point within or outside their enclosure that we call a reference point. The finding of heading-direction modulation relative to reference points identifies a novel representation encoded in the neuronal responses of the dorsal hippocampus.

Varicella-zoster infections in pediatric renal transplant recipients.

Varicella-zoster infections developed in ten of 76 children receiving a renal transplant during 1973 to 1978. Two children had varicella and one died during this infection. Eight children had herpes zoster and one experienced encephalitis. In the latter group, reduction of prednisone and azathioprine therapy resulted in rejection and loss of the graft in two of three patients in whom this drug therapy was altered.

Negative echo in the density evolution of ultracold fermionic gases.

We predict a nonequilibrium critical phenomenon in the space-time density evolution of a fermionic gas above the temperature of transition into the superfluid phase. On the BCS side of the Bose-Einstein condensation-BCS crossover, the evolution of a localized density disturbance exhibits a negative echo at the point of the initial inhomogeneity. Approaching the Bose-Einstein condensation side, this effect competes with the slow spreading of the density of bosonic molecules. However, even here the echo dominates for large enough times. This effect may be used as an experimental tool to locate the position of the transition.

Possible urate nephropathy of the newborn infant as a cause of transient renal insufficiency.

Oliguric renal failure, bilateral renal enlargement, and hyperuricemia were noted in three term infants. The findings on intravenous pyelography and radionuclide renography were consistent with intratubular obstruction to urinary outflow in two of the infants. The onset of diuresis appeared to follow intravenous pyelography in these infants. Urinary urate crystalluria was prominent in each infant in the first few days after the onset of diuresis, during which normal serum urate concentrations and normal renal function were established.