A study of reactive sputter etching by directed ion beams and R.F. plasmas.

This work compares the alternative methods of etching silicon semiconductor materials. Conventional methods of pattern delineation using aqueous etchants are being replaced for some applications by dry processing. The reasons for the move towards plasma and ion beam etching are examined particularly in relation to very large scale integration (VLSI) technology and the required reduction in feature size. A review of the published information on the use of reactive gas plasmas shows that this etching process is capable of producing vertical profiles without loss of pattern definition in lum. features. Noble gas ion beam sputtering, another alternative dry etching process, has some advantages over plasma etching but does not compare favourably in terms of material etch-rate selectivity and profile replication. Reactive ion beams produced by heated filament sources etch silicon compounds more rapidly than argon beams, but undesirable topographical features such as "facets" and "trenches" may be observed after beam energies greater than about 1 keV have been used. The total beam current and current distribution have been determined for a medium sized (B93) Saddle-Field source. The etch rates of several materials were greater with a fluorocarbon beam than with an argon beam produced by this source. Examination of profiles produced by etching silicon dioxide with beams from the B93 source injected with either CHF3 or CF4 showed no evidence of sputtering induced artefacts or lateral attack due to the diffusion of chemically reactive fragments. The results of reactive ion beam etching (RIEB) with a Saddle-Field source suggest that chemical attack predominates over sputtering. A two stage mechanism is proposed in which the incident particles cause bond cleavage at the surface followed by addition and abstraction reactions, leading ultimately to the formation of volatile products. The possible commercial applications of RIBE with Saddle-Field sources are discussed, and suggestions are advanced for further work in this area

The Prince and the railwaymen: the origins of the 1920 Amalgamated Society of Railway Servants' strike

This paper provides an account of the events which culmininated in the 1920 railways strike. Focusing on the period 1913-1920. it exa1nines the Amalgamated Society of Railway Servants' (ASRS) executive's attempts to provide for the members needs in the face of ever increasing difficulties. It also provides some insight into the history of other labour groups and illustrates how workers in New Zealand united once rheir problems became too big to handle alone. Nevertheless the policies followed by the ASRS execurive were always those which were expected to yield the most benefits to ASRS numbers despite the feelings of orher labour groups

Exploring the anthelmintic properties of Australian native shrubs with respect to their potential role in livestock grazing systems

We measured in vitro anthelmintic activity in extracts from 85 species of Australian native shrub, with a view to identifying species able to provide a degree of worm control in grazing systems. Approximately 40% of the species showed significant activity in inhibiting development of Haemonchus contortus larvae. The most active extracts showed IC50 values of 60–300 mg/ml. Pre-incubation with polyvinylpolypyrrolidine removed the activity from some extracts, implicating tannins as the bioactive agent, while in other cases the pre-incubation had no effect, indicating the presence of other anthelmintic compounds. Plant reproductive maturity (onset of flowering or fruiting) was associated with increasing anthelmintic activity in some species. Variability was observed between plants of the same species growing in different environments, while variation between individual plants of the same species within a single field suggests the existence of distinct chemotypes. Significant activity against adult H. contortus worms in vitro was also demonstrated in a limited number of extracts tested against this life stage. Our study indicates that there is potential for Australian native shrubs to play an anthelmintic role in grazing systems, and highlights some plant biology factors which will need to be considered in order to maximize any anthelmintic effects.A. C. Kotze, J. O’Grady, J. Emms, A. F. Toovey, S. Hughes, P. Jessop, M. Bennell P. E. Vercoe and D. K. Revel

New Zealand labour force participation: the ninety years to 1981

This paper emanines labour force participation in New Zealand from l891 to 1981. It commences with a brief review of previous work in the area and then draws upon data from the New Zealand Census of Population and Dwellings to investigate participation races. Age-specific data for Maoris, non-Maoris and Pacific Island Polynesians are analysed and male rates are compared with female rates. The paper concludes by identifying unresolved questions requiring further research

How to Remove a Dumbbell Tumour of the Sciatic Notch

Purpose.To look at a method for treating soft tissue sarcoma of the retroperitoneal area

Sexual Dimorphism in Primate Aerobic Capacity: A Phylogenetic Test

Male intrasexual competition should favour increased male physical prowess. This should in turn result in greater aerobic capacity in males than in females (i.e. sexual dimorphism) and a correlation between sexual dimorphism in aerobic capacity and the strength of sexual selection among species. However, physiological scaling laws predict that aerobic capacity should be lower per unit body mass in larger than in smaller animals, potentially reducing or reversing the sex difference and its association with measures of sexual selection. We used measures of haematocrit and red blood cell (RBC) counts from 45 species of primates to test four predictions related to sexual selection and body mass: (i) on average, males should have higher aerobic capacity than females, (ii) aerobic capacity should be higher in adult than juvenile males, (iii) aerobic capacity should increase with increasing sexual selection, but also that (iv) measures of aerobic capacity should co-vary negatively with body mass. For the first two predictions, we used a phylogenetic paired t-test developed for this study. We found support for predictions (i) and (ii). For prediction (iii), however, we found a negative correlation between the degree of sexual selection and aerobic capacity, which was opposite to our prediction. Prediction (iv) was generally supported. We also investigated whether substrate use, basal metabolic rate and agility influenced physiological measures of oxygen transport, but we found only weak evidence for a correlation between RBC count and agility.Human Evolutionary Biolog

Periosteal Osteosarcoma: A Review of 17 Cases with Mean Follow-up of 52 Months

Purpose: Periosteal osteosarcomas are rare cartilage-rich bone tumours characterized by a juxtacortical eccentric position and are normally regarded oncologically as of intermediate to high grade.Their low incidence is mirrored by a small number of reported cases in the world literature. While there is general agreement that wide surgical excision is required, there is a paucity of evidence regarding adjuvant therapy. Previous reports have not indicated any consistent approach to this to allow appraisal

Consultancy-Based Projects

This chapter will:; ; ; Show how consultancy work can inform business discourse teaching;; ; ; Discuss how needs analysis and communication audits can be used to generate recommendations for teaching and training;; ; ; Profile a number of consultancy-based business discourse projects and show how they have informed training and course development;; ; ; Provide a case study, together with a set of tasks appropriate for the business discourse classroom, and a set of further readings

Race and sex: teachers' views on who gets ahead in schools?

The research reported here was part of a large study of the impact of age, disability, race and sex on the teaching profession in England. The basic question asked in this research was how do these factors interact with career aspirations and achievements of classteachers, promoted teachers and headteachers? There were three different data sources: a large postal survey drawn from diverse geographic regions across England with over 2000 respondents; face‐to‐face individual interviews with over 100 teachers in 18 case study schools from across all of the main regions of England; discussions with special interest groups of teachers. Not surprisingly, the answer to the above question was complex. Nonetheless, the paper's conclusion highlights some of the noteworthy themes across this broad sample of teachers from primary, secondary and special schools