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We demonstrate efficient heralded generation of high purity narrow-bandwidth single photons from a transient collective spin excitation in a hot atomic vapor cell. Employing optical homodyne tomography, we fully reconstruct the density matrix of the generated photon and observe a Wigner function reaching the zero value without correcting for any inefficiencies. The narrow bandwidth of the photon produced is accompanied by a high generation rate yielding a high spectral brightness. The source is, therefore, compatible with atomic-based quantum memories as well as other applications in light-atom interfacing. This Letter paves the way to preparing and measuring arbitrary superposition states of collective atomic excitations. [ABSTRACT FROM AUTHOR]

A course of treatments with electroconvulsive shock (ECS) has been reported to reestablish L-dopa efficacy in patients with advanced Parkinson's disease. We wished to determine if ECS could modify L-dopa and dopamine metabolism in an animal model of Parkinson's disease. Therefore, we administered repeated ECS (8 ECS at 48 hr intervals) to rats with partial destruction of the nigrostriatal dopamine pathway and used the cerebral microdialysis technique to monitor extracellular concentrations of dopamine and dopamine metabolites (DOPAC and HVA) in the corpus striatum. The control group of animals received sham-ECS treatments. Basal dopamine levels were decreased by 20% in animals receiving repeated-ECS versus sham-ECS. DOPAC levels, on the other hand, were increased by 84% in animals receiving repeated-ECS. HVA levels were equal in the two groups. Following L-dopa administration, dopamine and HVA levels increased equally in control animals and animals which had previously received repeated-ECS. DOPAC concentrations were uniformly greater in rats receiving repeated-ECS. When ECS was administered acutely, dopamine levels increased 390% and returned to baseline values in 75 minutes, DOPAC and HVA were unchanged, and 5HIAA levels decreased 30%. We conclude that 1) acute ECS administration produces a transient, marked release of striatal dopamine and 2) repeated ECS can reset the level of basal dopamine release, a finding compatible with ECS-induced dopamine receptor supersensitivity, and 3) neither single nor repeated administration of ECS has a major effect on the formation of dopamine or HVA from exogenously administered L-dopa although there was a strong tendency for increased DOPAC formation. ECS may exert its putative antiparkinsonian effect by enhancing dopamine receptor sensitivity. [ABSTRACT FROM AUTHOR]

Thirty-eight cases of basal ganglia calcification imaged on computed axial tomography were reviewed. Most cases were felt to represent senescent calcification. The possibility of a vascular aetiology in this group is discussed. A less common group of patients was identified with calcification secondary to abnormalities in calcium metabolism or radiation therapy. Three cases of basal ganglia calcifications were detected in juvenile epileptic patients receiving chronic anticonvulsants. These cases may be related to abnormalities in calcium metabolism and alkaline phosphatase activity. Clinical evidence of basal ganglia abnormality was generally absent demonstrating the preservation of neuronal pathways in most cases. [ABSTRACT FROM AUTHOR]