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In the Ross Sea region, most South Polar Skuas (Stercorarius maccormicki) nest near Adelie Penguin (Pygoscelis adeliae) colonies, preying and scavenging on fish, penguins, and other carrion. To derive a relationship to predict skua numbers from better-quantified penguin numbers, we used distance sampling to estimate breeding skua numbers within 1000 m of 5 penguin nesting locations (Cape Crozier, Cape Royds, and 3 Cape Bird locations) on Ross Island in 3 consecutive years. Estimated numbers of skua breeding pairs were highest at Cape Crozier (270,000 penguin pairs; 1099 and 1347 skua pairs in 2 respective years) and lowest at Cape Royds (3000 penguin pairs; 45 skua pairs). The log–log linear relationship (R 2 = 0.98) between pairs of skuas and penguins was highly significant, and most historical estimates of skua and penguin numbers in the Ross Sea were within 95 % prediction intervals of the regression. Applying our regression model to current Adelie Penguin colony sizes at 23 western Ross Sea locations predicted that 4635 pairs of skuas now breed within 1000 m of penguin colonies in the Ross Island metapopulation (including Beaufort Island) and northern Victoria Land. We estimate, using published skua estimates for elsewhere in Antarctica, that the Ross Sea South Polar Skua population comprises ~50 % of the world total, although this may be an overestimate because of incomplete data elsewhere. To improve predictions and enable measurement of future skua population change, we recommend additional South Polar Skua surveys using consistent distance-sampling methods at penguin colonies of a range of sizes.

Biological control systems are integral to New Zealand’s success as a nation reliant on exporting quality agricultural, forestry and horticultural products. The likely impacts of climate change projections to 2090 on one weed and four invertebrate management systems in differing production sectors were investigated, and it was concluded that most natural enemies will track the changing distributions of their hosts. The key climate change challenges identified were: disparities in natural enemy capability to change distribution, lack of frosts leading to emergence of new pests and additional pest generations, non-target impacts from range and temperature changes, increased disruptions caused by extreme weather events, disruption of host-natural enemy synchrony, and insufficient genetic diversity to allow evolutionary adaptation. Five classical biological control systems based on the introduced species Longitarsus jacobaeae, Cotesia kazak, Aphelinus mali, Microctonus aethiopoides and Microctonus hyperodae are discussed in more detail.

The objective of this work was to compare the efficiency of four pathometric variables, i.e., grading scale, infection intensity index, global leaf disease index, and global incidence and severity index, in evaluations of the passion fruit/Cowpea aphid-borne mosaic virus (CABMV) pathosystem. In ‘yellow’ passion fruit plants, mechanically inoculated with CABMV isolates, the degree of association between leaf symptoms and the total fruit yield was determined, as well as the relative infectivity between viral isolates. Only infection intensity index and the global incidence and severity index presented significant regressions with yield (p = 0.007 and 0.006, respectively). These two pathometric variables could also distinguish groups of viral isolates inducing different severity levels (0.001 and 0.002, respectively). The results indicate that infection intensity index and global incidence and severity index are equally efficient in early identification of passion fruit populations with a higher resistance/susceptibility level to CABMV, and can be helpful in identifying more severe CABMV isolates, both useful aids in breeding programs.

The last two years have seen a renaissance of monoclonal antibodies for the treatment of disease. Of the eight antibodies currently approved for human therapy, two are for the treatment of cancer. In large part, the revival of antibodies has been driven by technology developments geared toward making antibodies less likely to elicit an anti-antibody response in humans. The development of transgenic mice, XenoMouse animals, capable of making fully human antibodies offers new opportunities for generating antibodies of therapeutic quality. Recently, this technology has been applied to the generation of a fully human antibody to the epidermal growth factor receptor. A description of the development of this antibody serves to illustrate the power and ease of use of XenoMouse technology.

Mode shape measurement of rectangular plates, one of a classical issue in structural vibrations, has been widely investigated for a long time. In principle, multiexcitation must be applied in order to obtain a single normal mode among many while shaking the structure at a single frequency. Yet this is not always the case in engineering practice. The reason is that computer-based multiexcitation usually involves expensive equipment and massive test work. Consequently, monoexcitation is being extensively employed as an inexpensive alternative. However, it only gives approximation of mode shapes with varying accuracy, depending largely on the test condition, such as available spatial resolution, excitation frequency, and location. With sparse spatial resolution of the conventional measurement scheme, such as piezoelectric accelerometer array, the consequential results are usually thought acceptable as one can hardly detect any minor differences between a normal mode and a contaminated mode shape.

Work on directional properties in granular media is briefly reviewed with an emphasis on the angular frequency of normals to particle contact tangents. Data from a two dimensional model material is compared with that of sand sheared in plane strain with a similar stress path. This stress path included a chosen sudden change in major principal stress direction.

Levels of free tryptophan in the leaves, phloem and xylem saps of Ricinus communis L. were determined by colorimetric assay. Values of 0.38 μg ml(-1) in root pressure sap and 96.0 μg ml(-1) in phloem sap were recorded. Tryptophan levels were highest in mature and senescing leaves. Levels of indoleacetic acid (IAA) in the phloem sap and leaves were determined by gas chromatography-mass spectrometry using a deuterated internal standard. A mean value of 13.0 ng ml(-1) was recorded in phloem sap. The distribution in the leaves showed an inverse relationship to that of tryptophan, being highest in young leaves.

The neurosecretory system of the freshwater snail Bulinus truncatus was investigated. With the Alcian blue-Alcian yellow (AB/AY) staining method at least 10 different types of neurosecretory cells (NSC) were distinguished in the ganglia of the central nervous system. The differences in staining properties of the NSC - with AB/AY the cells take on different shades of green and yellow - are borne out at the ultrastructural level: the NSC types contain different types of neurosecretory elementary granules. The neurosecretory system of B. truncatus is compared to that of Lymnaea stagnalis, the species which has received the most attention among the pulmonates. It appears from the comparison that the systems of both species show many similarities, although some differences are also apparent.

CELL FUSION has been used to study problems in genetics, neoplasia and virology1. Its application to immunology was initiated by the experiments of Kohler and Milstein2, in which it was shown that a myeloma cell (a neoplastic B cell) could be fused with a normal antibody-producing B cell, and that the hybrids continued to secrete the specific antibody of the latter and grew as permanent lines. This type of fusion has since been used to produce homogeneous antibodies to a variety of antigens3,4. The same principle can also be applied to T cells, with the aim of producing T-hybrid lines with characteristic T-cell functions, such as cytotoxicity or the ability to help or suppress the responses of other lymphocytes. Recently, fusion of T cells with T-lymphoma cells has been described, leading to the establishment of lines carrying markers characteristic of the normal T-cell partner5–7, and some lines with T-cell activities have been reported8,9. We describe here the production of a hybrid line which exhibits a characteristic T-cell function, namely, specific suppression of the antibody response. The hybrid cells produce a suppressor molecule or ‘factor’ which binds to an antigen, sheep red blood cells (SRBC), and specifically suppresses the antibody response to this antigen in vitro. The factor is non-immunoglobulin, but carries determinants of the H–2 complex.

The association constant of the NaSO 4 − complex has been determined using a sodium-selective electrode in an aqueous medium of 0.5 M ionic strength at 25°C. The constant calculated was 2.5±0.2, and no evidence was found under the present conditions for the existence of higher complexes.

The effect of reinforcing PVDF with short carbon fibres was studied by injection moulding commercially available and laboratory compounded materials, with the result that components with increased tensile strength and modulus were produced. The extent of the improvements in properties was influenced by the processing techniques used. In order to ascertain the practical applications of such a material, an investigation of the integrity of butt-fusion welds of the material both to itself and to the unfilled material, was carried out, and on the basis of the findings a procedure for jointing two filled components is proposed. The overall conclusion can be expressed as a strong vindication of the use of both filled and unfilled PVDF as practical engineering materials.

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Measurements of particle packing by radiography have been analysed in terms of a general geometrical model.

The tendency in granular media to change volume during shear, known as dilatancy, was discussed first in 18861 and subsequently by other workers2–5. Strength and resistance to slow deformation can be profoundly affected by dilatancy and this is important for the bulk handling of materials in the process industries and soil behaviour in civil engineering. Here we propose a minimal form of local collapse as a mechanism of slow steady-state deformation, complementing the familiar mechanism of potentially expansive sliding and rolling. Both are applied to ideal frictionless grains and involve, respectively, maximum and minimum rates of internal energy dissipation. Subsequent comparison to the behaviour of real granular material shows surprising similarities. Apparently, our proposed very simple idealization identifies the mechanisms in real materials and provides the possibility of quantitative predictions.