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Trends in human immunodeficiency virus (HIV) counselling and antibody testing at a London clinic for sexually transmitted diseases showed substantial changes over a 12 month period. From around 100 a month in the summer of 1986 the numbers of people attending rose substantially to 276 in October 1986 and 475 in November at the time of the campaign in the popular press. They rose further still, to 700, at the time of AIDS (acquired immune deficiency syndrome) week in March 1987. In April they fell to the levels seen six months previously. Apart from this increase in overall numbers the proportions of women and heterosexual men who were seen increased.

The involvement of the brain, lungs and kidneys was studied in a lethal rat malaria. Lewis inbred rats were infected with Plasmodium berghei K173. The disease proved fatal within 10-14 days. Parasitaemia showed an increase of up to 43% parasitised red blood cells on Day 10 p.i. The haematocrit decreased from 50% to 12%. The systolic blood pressure dropped from 99 to 56 mmHg. The lactate dehydrogenase activity rose to 2,543 U/l. BUN and serum creatinine doubled during the course of the disease. The transaminases increased tenfold and the cholinesterase decreased from 943 U/l to 271 U/l. Morphologically the kidneys showed an immune complex glomerulo-nephritis with a normal tubulo-interstitial system. The brain, heart and lungs were normal by light microscopic examination. Marked anaemia and shock were the main causes of death in the above-mentioned specimen rat, showing that the course of the disease is significantly different from lethal infections in humans with Plasmodium falciparum who show severe pulmonary, renal and cerebral complications.

The laboratory has been active for some time in the development of improved desalination equipment to provide potable water at advanced bases. A review of the current literature on the physics of boiling disclosed a consensus that (1) nucleation is necessary for boiling, (2) nucleation is accomplished by sites of certain sizes only, and (3) the amount of superheat above the boiling point that is necessary for bubble formation is a function of site orifice diameter. Because no supporting theory accompanied the latter two observations, a study was made to determine why these limiting factors should apply--if in fact they do. A simple theory derived by the author indicated, on the contrary, that for a given wetting angle at the solid-vapor-liquid interface, the superheat necessary should be a function of the effective radius of vapor bubbles as determined by the wetting angle and the angle formed by the site's walls. This hypothesis was tested using a small copper hot plate with several relatively large sites (on the order of 1 to 2 mm in diameter); nucleation proved possible with superheats of only a few degrees Fahrenheit. Although steam would form a bubble, the emergence and growth of the bubble was inhibited by the thickness of the boundary layer, because a large radius bubble would penetrate to the area in which the covering layer was at or below the boiling point. The vapor within the bubble would therefore be condensed by this relatively cooler water.

A study is made to explore promising mechanisms of heat transfer which may be used to develop more efficient sea-water distillation units. As a basis of investigation, an extensive research survey of low-temperature- difference boiling heat transfer is briefly summarized, with the conclusion that with the present understanding of ebullition there is little prospect of achieving the desired heat transfer with active boiling. The metal-to-fluid superheat necessary to form a steam bubble with known types and sizes of nucleation sites prevents ebullition except with minimum temperature differences of 8 to 10F between the temperature of the metal wall and the saturation temperature of the fluid. The concept of evaporation from a very thin film without boiling is considered in detail, and two small experiments are reported. It is shown, both theoretically and experimentally, that very high evaporation rates can be obtained with the very thin film technique; methods of maintaining a thin film continuously in a practical vapor-compression still are considered. A single-tube experiment, in which methods of introducing feed water and checking probable scaling problems will be studied, is described as the next phase of this task. (Author)

In support of planned development of construction systems for precise excavation and drilling in the deep ocean floor, a study of the potential problems which might be encountered has been made. Two Deep Ocean Technology (DOT) efforts are considered, and two major subsystems are described. The first subsystem is a seafloor excavator which can shape the ocean floor, prepare trenches and drill shallow foundation holes. To avoid the problems of man in undersea environment, this equipment will be unmanned, and remotely controlled by computer and/or numerical techniques. The primary work function will be similar to a conventional milling machine, with similar ability to bore shallow holes. The second subsystem is for penetration of ocean bottom rock with large holes, sealing off the cavity with a prepared steel structure, dewatering, and lateral tunneling at one-atmosphere pressure. Initial penetration will be by equipment similar to large mining or tunneling moles, recent technology in rock disintegration may allow use of a less massive machine with low thrust and torque.

A small pulse jet engine formerly used for heat transfer studies was operated briefly in a section of a model tunnel, the size of which is representative of those found in Vietnam. Because the noise had been a continual problem in doing the original heat transfer research, it was predicted that a larger version might be suitable for tunnel clearance, provided the sound intensity attenuation with distance from the tunnel's mouth was not too rapid. Free field tests as well as those in a single right angle of a 3 x 3 foot cross section duct showed that attenuation was not rapid. It was concluded that a larger engine suitably mounted at the tunnel might provide a lightweight, convenient noise source for the intended purpose.

Objective: To describe the use of hospital and community services for children infected with HIV and estimate the cost per patient-year by stage of HIV infection during the era of antiretroviral monotherapy. Design: Data on the use of hospital services were collected from case notes; the use of statutory and nonstatutory community services was recorded through diaries and interviews. Total cost estimates were calculated from unit costs from relevant hospital departments and community organisations. Setting: Children managed at St. Mary’s Hospital (London, England) between 1 January 1986 and 31 December 1994, some of whom used statutory and nonstatutory community services in South East England between 1 November 1994 and 31 May 1996. Patients and participants: 118 children with positive HIV antibody status. Main outcome measures and results: Mean inpatient days, outpatient visits, tests and procedures performed, drugs prescribed, community services used, associated unit costs and average cost estimates per patient-year by stage of HIV infection (1995/1996 values), and lifetime costs. Service provision during the study period was predominantly hospital-based. The use of services increased for different stages of HIV infection and increased with increasing severity of HIV infection. A shift from an inpatient-based to an outpatient-based service was seen between the periods 1986 to 1991 and 1992 to 1994. As symptoms evolved, children used more hospital inpatient services, with an accompanying shift in the use of community services from general services, such as schooling, to increased use of nurses, social care and home help. The estimated total cost of hospital and community care was £18 600 per symptomatic non-AIDS patient per year and £46 600 per AIDS patient per year. Similar estimates for children with indeterminate HIV infection and asymptomatic infection amounted to £8300 and £4800 per patient-year, respectively. Nondiscounted lifetime costs for hospital care amounted to £152 400 (£44 300 to £266 800) compared with discounted lifetime costs of £122 700 (£42 000 to £182 200); nondiscounted lifetime costs for community care amounted to £24 300 (£7900 to £41600) compared with discounted lifetime costs of £21 000 (£6800 to £32 000). Conclusions: The continued emphasis on the use of hospital services may be due to the small number of children infected with HIV, most of whom lived in the London metropolitan area where specialist care was concentrated in a few centres. A shift from an inpatient- to an outpatient-based service was observed over time; the advent of the use of combination antiretroviral therapy in this population may further facilitate a shift in service provision and promote shared care between specialist centres, local hospitals and community-based services.