This paper describes a new Heterodyne Array Receiver Program (HARP) and Auto‐Correlation Spectral Imaging System (ACSIS) that have recently been installed and commissioned on the James Clerk Maxwell Telescope. The 16‐element focal‐plane array receiver, operating in the submillimetre from 325 to 375 GHz, offers high (three‐dimensional) mapping speeds, along with significant improvements over single‐detector counterparts in calibration and image quality. Receiver temperatures are ∼120 K across the whole band, and system temperatures of ∼300 K are reached routinely under good weather conditions. The system includes a single‐sideband (SSB) filter so these are SSB values. Used in conjunction with ACSIS, the system can produce large‐scale maps rapidly, in one or more frequency settings, at high spatial and spectral resolution. Fully sampled maps of size can be observed in under 1 h. The scientific need for array receivers arises from the requirement for programmes to study samples of objects of statistically significant size, in large‐scale unbiased surveys of galactic and extra‐galactic regions. Along with morphological information, the new spectral imaging system can be used to study the physical and chemical properties of regions of interest. Its three‐dimensional imaging capabilities are critical for research into turbulence and dynamics. In addition, HARP/ACSIS will provide highly complementary science programmes to wide‐field continuum studies and produce the essential preparatory work for submillimetre interferometers such as the Submillimeter Array (SMA) and Atacama Large Millimeter/Submillimeter Array (ALMA).

The Arcminute Microkelvin Imager is a pair of interferometer arrays operating with six frequency channels spanning 13.9-18.2 GHz, for observations on angular scales of 30 arcsec-10 arcmin and for declinations greater than −15 • ; the Small Array has a sensitivity of 30 mJy s −1/2 and the Large Array has a sensitivity of 3 mJy s −1/2 . The telescope is aimed principally at Sunyaev-Zel'dovich imaging of clusters of galaxies. We discuss the design of the telescope and describe and explain its electronic and mechanical systems.

To determine whether donated blood samples in African countries could be pooled, then tested for the presence of human immunodeficiency virus (HIV) antibodies with a single test without loss of accuracy, a single test on five pooled samples was used, followed by individual testing of positive pools. This resulted in no loss of either sensitivity or specificity. Pooling 10 samples resulted in a loss of sensitivity for low antibody titre specimens. Pooling reduced the costs of screening by 70% and time needed for analysis. It is concluded that pooling of five samples for HIV screening may result in a substantial reduction in costs; in countries where the prevalence of HIV is higher than the 2-3% found in Zimbabwean donors, however, savings may not be as great.

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Objective: To describe the haematologic features of the HIV infection in adult Zimbabweans and compare the features in the different clinical stages of the disease. Design: Descriptive cross sectional study. Setting: Parirenyatwa Hospital, a tertiary and referral medical centre in Harare, and the blood donor clinics of the Blood Transfusion Service in Harare. Subjects: Patients attending HIV outpatients clinics or receiving inpatient care at Parirenyatwa Hospital and asymptomatic persons donating blood at the BTS Harare. Main Outcome M easures: Full blood counts and bone marrow cell counts and morphology. Results: Blood cytopenia was found in 47.5% of adults with HIV infection. The most frequent abnormalities were lymphopenia (31.5%); anaemia (30.8%); neutropenia (29.6%); thrombocytopenia (24.7%); eosinophilia (23.5%) and leucopenia (11.7%). Frequency of anaemia in the AIDS and symptomatic groups (43.4% and 24.5% respectively) was greater than in the carriers (6.7%), while the frequency of other cytopenias and of eosinophilia was about the same in all groups. There was also a general lack of association between the severity of haematologic abnormalities and the clinical stage of the disease. Conclusion: Severe haematologic changes occur frequently in HIV infection and AIDS but routine full blood count may not be helpful in the monitoring of the disease or the prediction o f onset of AIDS.