Our concept of the structure and function of the normal and diseased brain has developed throughout the centuries. The first stage in the discovery of the brain stretched over three millennia, from the earliest descriptions by the Egyptians in the sixteenth century B.C. to the comprehensive anatomical treatise of Vesalius. The invention of the light microscope brought to the eye a previously invisible world, and heralded the beginnings of the systematic histological investigation of the immensely complex cellular networks of the brain. With the advent of electron microscopy, the organelles and connections of brain cells have been revealed, and the new era of molecular biology has begun. Neuropathology, which concerns itself with diseases of the brain, spinal cord, nerve and muscle, has enormously benefited from these developments to establish the morphological basis of diseases of the nervous system.

Plasmodium falciparum parasites use multiple ligand-receptor interactions to invade human erythrocytes. Variant expression levels of members of the PfRh and PfEBA ligand families are associated with the use of different erythrocyte receptors, defining invasion pathways. Here we analyse a major polymorphism, a large sequence deletion in the PfRh2b ligand, and erythrocyte invasion profiles in uncultured Senegalese isolates. Parasites vary considerably in their use of sialic acid-containing and protease-sensitive erythrocyte receptors for invasion. The erythrocyte selectivity index was not related to invasion pathway usage, while parasite multiplication rate was associated with enhanced use of a trypsin-resistant invasion pathway. PfRh2b protein was expressed in all parasite isolates, although the PfRh2b deletion was present in a subset (~68%). Parasites with the PfRh2b deletion were found to preferentially utilize protease-resistant pathways for erythrocyte invasion. Sialic acid-independent invasion is reduced in parasites with the PfRh2b deletion, but only in isolates derived from blood group O patients. Our results suggest a significant role for PfRh2b sequence polymorphism in discriminating between alternative erythrocyte receptors for invasion and as a possible determinant of virulence.

The study of naturally-occurring radiation and its associated risk is one of the preoccupations of bodies responsible for radiation protection. Cosmic particle flux is significantly higher on board aircraft that at ground level. Furthermore, its intensity depends on solar activity and eruptions. Due to their professional activity, flight crews and frequent flyers may receive an annual dose of some millisieverts. This is why the European directive adopted in 1996 requires the aircraft operators to assess the dose and to inform their flight crews about the risk. The effective dose is to be estimated using various experimental and calculation means. In France, the computerized system for flight assessment of exposure to cosmic radiation in air transport (SIEVERT) is delivered to airlines for assisting them in the application of the European directive. This dose assessment tool was developed by the French General Directorate of Civil Aviation (DGAC) and partners: the Institute for Radiation Protection and Nuclear Safety (IRSN), the Paris Observatory and the French Institute for Polar Research - Paul-Emile Victor (IPEV). This professional service is available on an Internet server accessible to companies with a public section. The system provides doses that consider the routes flown by aircraft. Various results obtained are presented.

The aims of this report are, firstly, to review the activities of Commission 5 during the period since the IAU General Assembly in Delhi in November 1985 and, secondly, to draw attention to other relevant activities. It is based mainly on contributions from the Chairmen of the working groups and other members of the Commission, but it also includes some items of general interest that have been taken from the Commission’s Newsletter. The Working Groups and their Chairmen are as follows:

Two dimensional maps obtained with the Nançay Radioheliograph at 169 MHz from 1980 are used to describe and identify the features of the quiet sun at meter wavelengths.

The report period 1982-84 was characterized by an again increased volume of material processed in data and abstracting centers, and by a growing clientele particularly of online services. The Working Groups of Commission 5 seek continued consultation with research object commissions so that the advanced documentation technology be efficiently employed toward specific demands of subject areas as to indexing, tagging, comprehensive, selective and inter-discliplinary retrievals. The guideline library for these purposes has been augmented by the First Dictionary of the Nomenclature of Celestial Objects by A. Fernandez, M.-C. Lortet and F. Spite (Astr. Astrophys. Suppl. 52 no.4, 1983) and by the Guide to the Presentation of Astronomical Data by G.A. Wilkins (CODATA Bull.46 1982); a new draft of the IAU Style Manual is before the IAU EC.

The range of activities of Commission 5 has considerably broadened over the last decade, compared with its originally bibliographical emphasis. This fact is also reflected in the new name of this Commission as adopted at the Montreal conference. The increased production of astronomical data, the growing role of data centers in the organisation and retrieval of information, as well as the editorial and bibliographic processing of the large number of primary papers have indicated the need for new and more efficient coordinative guidelines. Several documents have been published and are under consideration, or are in preparation, for the agenda at the IAU General Assembly in 1982.

In 1950, a few years after the detection of the Sun at radiowavelengths by Southworth (1945), two important points were already established:

1. 1 — The theory (Martyn 1946, Ginzburg, 1946) indicates that the thermal bremmstrahlung is dominant.

2. 2 — The transfer calculations by Smerd (1950) and the total flux measurements (Pawsey 1946, Pawsey and Yabsley, 1949) lead to a coronal temperature of one million degrees.