Experimental systems that are amenable to genetic manipulation can be used to address fundamental questions about genetic and nongenetic determinants of longevity. Analysis of large cohorts of ten genotypes of Drosophila melanogaster raised under conditions that favored extended survival has revealed variation between genotypes in both the slope and location of age-specific mortality curves. More detailed examination of a single genotype showed that the mortality trajectory was best fit by a two-stage Gompertz model, with no age-specific increase in mortality rates beyond 30 days after emergence. These results are contrary to the limited life-span paradigm, which postulates well-defined, genotype-specific limits on life-span and brief periods of intense and rapidly accelerating mortality rates at the oldest age.

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The liquid jet impact technique has been used extensively for the quantitative study of rain impact. Most of this work has been for normal impact. Although some angled impact studies have been pursued using jets, these have been purely of a qualitative nature. This paper develops the theory of angled drop impact. This allows the establishment of a method of correlating between angled drop and jet impact and obtaining ‘‘equivalent drop’’ curves for jet impact. The correlation is also applied to normal impact. For normal impact it is shown that the previously published equivalent drop curves need to be modified especially at low velocities. The results for both normal and angled impact are discussed with reference to the details of the jet profile, and it is shown that angled jets may be considered as having an average equivalent drop size. The theory of angled impact also explains the shape of damage marks produced by impact and why the amount of damage decreases so rapidly with increasing angle.

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An instrumental method for the individual, sequential or collective measurement of the physical and chemical properties of liquids is presented. A prototype of the fibre drop analyser (FDA), working at only one wavelength in the infrared, has been constructed and tested. The instrument has been used to measure individually surface tension, viscosity, refractive index and the chemical composition of the test solution. The instrument has the capability of simultaneously measuring all of these quantities in one measurement cycle and this possibility is discussed on the basis of one set of results obtained from the sugar processing industry. The instrument is also potentially capable of measuring electrochemical properties of a liquid and some preliminary results are presented. The laboratory FDA has been used to test a series of samples from a large cane sugar manufacturer's process and these measurements demonstrate that the FDA technology has the potential to be used as a remote optrode industrial process monitor for sucrose manufacture, and possibly in other industrial applications.