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Notes: A computational simulation of a dispersion of iron particles undertaken to study the influence of the magnetostatic interactions on the microstructure of a particle ensemble is reported herein. The simulation considers an equilibrium state derived from an initial random state by the force-bias Monte Carlo technique. This method favors particle moves in the direction of the magnetostatic forces. A three dimensional ensemble in zero field and a saturating field are studied. An approach which takes into account the magnetostatic interactions between clusters by allowing Monte Carlo moves of whole clusters has been developed. This approach leads to the formation of extended networks consisting of particles in strongly bound clusters which themselves interact and give rise to an extended network. This is similar to the long-range order observed in practical dispersions. The structure analysis is found to characterize the local order, being especially sensitive to anisotropy in the order produced by an aligning field.

Notes: Eight experiments aimed at improving methods for the village-based farming of giant clams were conducted in the Solomon Islands. The experiments focused on either improving the fitness of seed clams delivered to village farmers, assessing whether differential growth rates of seed clams in nursery tanks persisted during grow-out at farms, or testing the effects of alterations to the design of grow-out cages on the growth and survival of clams. We found that Tridacna squamosa (Lamarck) ‘seed’ transferred from land-based nursery tanks to a floating ocean nursery (FON) for ≈ 3 months at the end of the nursery phase were significantly larger than seed reared only in land-based nursery tanks. Similarly, T. maxima (Röding) placed in a FON for 2–5 months generally grew at a significantly greater rate than tank-reared ‘seed’. However, the use of FONs did not improve survival. There were no consistent differences in the growth and survival of fast- and slow-growing seed of T. derasa (Röding) at village sites when slow-growing seed were retained in the nursery until reaching a larger size. The survival of T. maxima was enhanced significantly by placing an insert of smaller mesh (a ‘settlement ring’) in grow-out cages for the first 2 months after delivery of seed to farmers. The settlement ring retained clams in cages until they found a suitable place to attach their byssal threads. Attempts to remove the sediment which impedes the attachment of T. maxima to the base of grow-out cages by perforating the substrate did not improve survival: the perforated substrate resulted in poor attachment of clams and harboured predators (Cymatium spp.). The survival of T. crocea (Lamarck) was not improved by ‘softening’ the concrete base of grow-out cages to simulate dead coral rock and to encourage the clams to burrow in the substrate. The survival of T. crocea in grow-out cages was enhanced significantly by enclosing the cages in fine mesh after the delivery of the seed clams to prevent predation and disturbance by juvenile wrasse, Thalassoma spp. The experiments indicate that the critical stage for village farming of giant clams is during the initial weeks following distribution of seed. Further research is needed to improve the survival of T. crocea and T. maxima during this phase.

Notes: Inequalities in health care provision: the relationship between contemporary policy and contemporary practice in maternity services in England Aim. The project Addressing Inequalities in Health: new directions in midwifery education and practice (Hart et al. 2001) was commissioned by the English National Board for Nursing, Midwifery and Health Visiting (ENB). Here, we draw on those research findings to consider current midwifery policy and practice in England. Background. Little guidance on providing equality of care exists for midwives. The Code of Conduct [United Kingdom Central Council for Nursing, Midwifery and Health Visiting (UKCC) 1992] makes no specific requirement for midwives to address issues of inequalities of health in their practice. Recent policy documents emphasize the need to work towards reducing inequalities and to target practice to `disadvantaged clients' without giving guidelines on how to identify and care for target groups. Methods. In-depth studies of midwifery education and service provision were conducted in three very different parts of England. Three months of fieldwork were undertaken at each site, comprising a series of interviews with midwifery educators, managers, students, midwives and service users. Focus groups were also held and observation of classroom sessions and midwifery practice undertaken. Findings. A lack of clear and specific strategies concerning inequalities in health was evident at managerial level. Patchy knowledge of current policy was also evident amongst practising midwives. Specific projects with disadvantaged clients usually resulted from a particular midwife's personal interest or evident local need. All midwives emphasized the importance of `equality of care'. How this was operationalized varied, and `individualized' or `woman-centred' care was assumed to encompass the concept. In the few examples where care was systematically targeted in accordance with policy directives, the midwife's public health role was increased. Conclusion. In the absence of a co-ordinated strategic vision driven by managers, practitioners find difficulty in prioritizing care and targeting resources to disadvantaged clients in line with policy directives. Tensions between policy and practice in the care of `disadvantaged' women clearly exist. Successful implementation of policy at practice level needs: commitment from managers; clarity of purpose in documentation; and provision of specific targets for practitioners. However, the latter should remain flexible enough for the delivery of care to be appropriate and sensitive to individual needs.

Notes: Ryegrass, some white clover cultivars (Grasslands Huia, Trifo, Barbian and Luclair) and lotus were grown in the presence of mineral nitrogen and at a range of phosphorus (P) supply. Ryegrass had the highest leaf inorganic P concentrations on a dry weight basis, and lotus the lowest. In the clovers and lotus shoot yield was correlated with inorganic P concentration; it was not correlated in ryegrass, although this was possibly a result of the stage of development of ryegrass when it was harvested. Ryegrass was always more efficient than the legumes in acquiring P and growing rapidly. When inorganic P concentration was expressed on the basis of DNA, lotus had concentrations intermediate between that of ryegrass and the clovers, i.e. lotus had at least as much inorganic P per unit of DNA as white clover. It is suggested that although lotus is more efficient than white clover in terms of the concentration of inorganic P on a dry weight basis, the amount of inorganic P required per ‘module of metabolism’ (or cell), is similar. Lotus also has larger cells than white clover and the relatively greater efficiency of lotus may lie at least partly in its ability to achieve an equivalent leaf area or weight with fewer cells, i.e. cytology contributes to efficiency.

Notes: Two cultivars of white clover (Ladino and Kent Wild White) and two cultivars of lotus (Grasslands Maku and G4703) were grown in pots of soil at low to moderate levels of phosphorus (P) supply. Nitrogen supply was by fixation. Cell size and nitrogen, phosphorus and chlorophyll content per cell were estimated from samples of leaf tissue. Maku lotus had larger cells and higher cellular contents of metabolites than the clovers. These measurements support earlier suggestions that, compared with white clover, the higher P-efficiency (dry matter per unit of internal P) of Maku lotus may be explained by cytological factors without recourse to explanations based on differences in nutrient metabolism. The relatively large cells and high metabolite levels per cell of Maku lotus appear to arise from its creation as an artificial tetraploid.

Notes: White clover (Grasslands Huia) and lotus (Grasslands Maku) were grown in pots of soil at a range of phosphorus supply, and reliant on symbiotic nitrogen fixation (SN plants) or entirely on mineral nitrogen (MN plants). Shoots increased in weight with phosphorus supply. White clover MN shoots were bigger than those of SN plants except at the lowest level of phosphorus supply; lotus MN shoots were only bigger than SN shoots at the highest level of phosphorus supply. Leaf growth rate and size increased with phosphorus supply but were not significantly affected by the nitrogen treatments.Estimates of cell size were made by determining DNA concentration, by digestion of tissue followed by counting and by taking vinyl impressions of epidermal cell surfaces. Lotus cells are bigger than those of white clover. ‘Digested’ cell sizes were not significantly affected by changes in phosphorus supply. Epidermal cell size increased with phosphorus supply, but the relationship was weaker in SN than in MN plants. Methods which give values for ‘average’ cell size are capable of detecting large-scale differences, but methods able to resolve cell heterogeneity are necessary for an accurate picture of the relationship between leaf growth and cellular nutrition.Average concentrations of total and inorganic phosphorus on a DNA basis did not differ between the species, contrary to concentrations on a dry weight basis, indicating that differences in phosphorus efficiency can be partly explained on the basis of average differences in cell size. Differences in inorganic phosphorous on a DNA basis at higher levels of supply suggested an additional intrinsic difference in cellular accumulation of inorganic phosphorus between the two species.

Notes: The origins of gyroremanent magnetization (GRM) in single domain particles are studied using a dynamic model based on the Landau–Lifschitz equation. The results show an asymmetry in the motion of the magnetic moment of a particle with three unequal axes of anisotropy. This asymmetry is interpreted in terms of an effective bias field which gives a good qualitative explanation of the origins of GRM.

Notes: For ion beams used for ion beam etching and sputtering in electronic device technology and for monitoring plasma wall interactions, a pyroelectric detector has been developed to measure the current density of neutralized ions and the fraction of the total beam which is neutralized. The pyroelectrically induced charges due to beam heating of a PVDF film and the deposited charge from the ion beam are measured with a charge sensitive and current sensitive amplifier, respectively. The pyroelectric detector has a sensitivity of 1000 V/W and 1/e response time of 2 s. Beam current densities in the range 0.01–100 μA/cm2 of 1 keV particle energy can be measured.

Notes: A comprehensive study of the stress release and structural changes caused by postdeposition thermal annealing of tetrahedral amorphous carbon (ta-C) on Si has been carried out. Complete stress relief occurs at 600–700 °C and is accompanied by minimal structural modifications, as indicated by electron energy loss spectroscopy, Raman spectroscopy, and optical gap measurements. Further annealing in vacuum converts sp3 sites to sp2 with a drastic change occurring after 1100 °C. The field emitting behavior is substantially retained up to the complete stress relief, confirming that ta-C is a robust emitting material. © 1999 American Institute of Physics.

Notes: The work function of tetrahedral amorphous carbon (ta-C) has been measured by Kelvin probe to lie in the range 4–5 eV, irrespective of its sp3 content or nitrogen addition. This implies that the surface barrier to emission is dominant and that emission changes caused by sp3 bonding or nitrogen addition are not directly due to changes in work function. Hydrogen, oxygen, and argon plasma treatments are all found to increase the emission of a-C, but hydrogen and argon treatments are found to reduce the work function while oxygen treatment increases it. Detailed studies of the surface with varying plasma treatment conditions suggest that the changes in emission arise mainly from changes in the surface microstructure, such as the formation of sp2 regions within the sp3 bulk. The need for local field enhancement mechanisms to account for emission over the sizeable barrier is emphasized, which may arise from local chemical nonhomogeneity, or formation of nanometer-size sp2 clusters embedded in an sp3 matrix. © 2000 American Institute of Physics.