The photodisintegration of cosmic ray nuclei by solar photons: the Gerasimova-Zatsepin effect revisted

The interesting possibility of measuring the masses of high energy cosmic ray particles by observing pairs of extensive air showers arriving at the earth nearly simultaneously was proposed some years ago by Gerasimova and Zatsepin (1960). Such showers would be created by the nuclear fragments originating as a result of the photodisintegration of massive nuclei interacting with the solar radiation field. In this paper we re-visit this possibility in the context of existing and proposed detectors of high and ultra-high energy cosmic rays considering a simple, yet realistic, model of the interplanetary magnetic field. The possibilty of observing the mass fragmentation of cosmic rays directly, however, remains challenging.Comment: 14 pages, 7 figures (3 ps + 4 jpg), Astroparticle Physics (in press) - typos corrected and other minor modification

Immunocytochemical and pharmacological evidence for GABAergic spiking local interneurons in the locust

In the locust thoracic nervous system, spiking local interneurons within a ventral midline population are stained by a polyclonal antibody raised against GABA. Their cell bodies, their primary neurites in ventral commissure II, and their prominent neurites in the perpendicular tract linking ventral and dorsal fields of fine branches are all stained. Individual interneurons in this population were labeled with Lucifer yellow after their receptive fields had been determined physiologically. Alternate sections were stained with the antibody. Some, but not all, of the spiking local interneurons labeled with Lucifer yellow are also stained with the antibody. Apart from having somata that lie more posteriorly within the midline population, the antibody-stained interneurons cannot be distinguished on morphological or physiological grounds from those that are unstained. The way in which this cytochemical heterogeneity within an otherwise homogenous population might arise during development is discussed. A second group of spiking local interneurons with similar sensory input to that of the ventral midline population, but with cell bodies in the anterior lateral region of the ganglion and primary neurites in ventral commissure I, are not stained. Interneurons in the midline group receive direct inputs from sensory neurons and some directly inhibit particular leg motor neurons that mediate interjoint and tactile reflexes. Picrotoxin reversibly blocks the inhibition of the motor neurons and therefore abolishes these reflexes. Immunocytochemical and pharmacological experiments thus suggest that inhibition by some spiking local interneurons may be mediated by GABA

Short communication: a hierarchy of items within Eysenck’s EPI

Based on the recent finding of a hierarchical scale for Neuroticism in the NEO-Five Factor Inventory, two further personality inventories: the Eysenck Personality Inventory and Goldberg’s International Personality Item Pool were analysed using the Mokken Scaling Procedure for hierarchical scales. Items from two dimensions of the Eysenck Personality Inventory: Neuroticism and Extraversion produced hierarchical scales of 12 and five items, respectively. The Neuroticism items ran from items expressing mild to more extreme worry and the Extraversion items ran from mild sociability to more extreme ‘showing off’. The utility of hierarchical scales in personality measurement is discussed in terms of furthering theoretical understanding of personality and also practical application. In addition, the reasons why only one of these scales should produce hierarchical sets of items is discussed