Searches for solar-influenced radioactive decay anomalies using Spacecraft RTGs

Experiments showing a seasonal variation of the nuclear decay rates of a number of different nuclei, and decay anomalies apparently related to solar flares and solar rotation, have suggested that the Sun may somehow be influencing nuclear decay processes. Recently, Cooper searched for such an effect in $^{238}$Pu nuclei contained in the radioisotope thermoelectric generators (RTGs) on board the Cassini spacecraft. In this paper we modify and extend Cooper's analysis to obtain constraints on anomalous decays of $^{238}$Pu over a wider range of models, but these limits cannot be applied to other nuclei if the anomaly is composition-dependent. We also show that it may require very high sensitivity for terrestrial experiments to discriminate among some models if such a decay anomaly exists, motivating the consideration of future spacecraft experiments which would require less precision.Comment: 8 pages, 4 figures (to appear in Astroparticle Physics

Beta-adrenergic blockade during memory retrieval in humans evokes a sustained reduction of declarative emotional memory enhancement.

Contains fulltext : 88606.pdf (publisher's version ) (Open Access)Memory enhancement for emotional events is dependent on amygdala activation and noradrenergic modulation during learning. A potential role for noradrenaline (NE) during retrieval of emotional memory is less well understood. Here, we report that administration of the beta-adrenergic receptor antagonist propranolol at retrieval abolishes a declarative memory enhancement for emotional items. Critically, this effect persists at a subsequent 24 h memory test, in the absence of propranolol. Thus, these findings extend our current understanding of the role of NE in emotional memory to encompass effects at retrieval, and provide face validity to clinical interventions using beta-adrenergic antagonists in conjunction with reactivation of unwanted memories in anxiety-related disorders

Propofol-induced deep sedation reduces emotional episodic memory reconsolidation in humans

Contains fulltext : 202689.pdf (publisher's version ) (Open Access)The adjustment of maladaptive thoughts and behaviors associated with emotional memories is central to treating psychiatric disorders. Recent research, predominantly with laboratory animals, indicates that memories can become temporarily sensitive to modification following reactivation, before undergoing reconsolidation. A method to selectively impair reconsolidation of specific emotional or traumatic memories in humans could translate to an effective treatment for conditions such as posttraumatic stress disorder. We tested whether deep sedation could impair emotional memory reconsolidation in 50 human participants. Administering the intravenous anesthetic propofol following memory reactivation disrupted memory for the reactivated, but not for a non-reactivated, slideshow story. Propofol impaired memory for the reactivated story after 24 hours, but not immediately after propofol recovery. Critically, memory impairment occurred selectively for the emotionally negative phase of the reactivated story. One dose of propofol following memory reactivation selectively impaired subsequent emotional episodic memory retrieval in a time-dependent manner, consistent with reconsolidation impairment