title: Reply to Mahowald and Gibson and to Heggarty: No problems with short words, and no evidence provided

authors: Pagel, Mark

abstract: Mahowald and Gibson (1) suggest that the shorter word length of frequently used words, and not their stability, could mean that chance sound correspondences account for the pattern of results we report for cognate relationships among proto-words in our study of seven Eurasian language families (2). However, their −0.24 correlation between the phonological length of contemporary English words and our measure of cognate class size is not relevant to the question of chance sound correspondences among the proto-words from different language families. What must be demonstrated is that shorter proto-words were more likely to be judged cognate simply on the basis of their length.

text: Reply to Mahowald and Gibson and to Heggarty: No problems with short words, and no evidence provided Mahowald and Gibson (1) suggest that the shorter word length of frequently used words, and not their stability, could mean that chance sound correspondences account for the pattern of results we report for cognate relationships among proto-words in our study of seven Eurasian language families (2). However, their −0.24 correlation between the phonological length of contemporary English words and our measure of cognate class size is not relevant to the question of chance sound correspondences among the proto-words from different language families. What must be demonstrated is that shorter proto-words were more likely to be judged cognate simply on the basis of their length.

year: 2013

title: Synthesis, Microstructure and Mechanical Properties of Titanium with Controlled Levels of Porosity

authors: Xu, Qian

subjects: Titanium

abstract: Porous titanium (Ti) products have many applications due to their excellent corrosion resistance, high strength-to-weight ratio, high specific surface area, etc. However, the major limitation is the expensive cost of porous Ti products because of the high raw materials costs and the difficulty of processing. The novelty of this research work is concerned with a study of a ceramic casting technique, slip casting, to create porous Ti products and the effect of porosity on the mechanical properties and gas permeability of Ti compacts. 

An optimised Ti slurry was developed from 43 vol.% of Ti powder, 0.3 dw.% of dispersant, 0.8 dw.% of plasticiser and 0.8 dw.% of binder, mixed with a balance of distilled water, which produced a viscosity of 290 cP. It was then poured into a plaster mould to form compacts with a green density of 45%. Thermal debinding was carried out at 320°C with an argon flow for 2 hours, followed by vacuum sintering different samples at 1000°C and 1200°C for 0.5 hours, respectively. The porous sintered compacts had satisfactory tensile strength with some plastic deformation. The increase in oxygen and carbon content during processing was minor. The results from this investigation suggested that slip casting is a potentially low-cost, simple manufacturing route for porous Ti products.

Porous Ti compacts with porosity in the range of 12.3 vol.% to 35.3 vol.% were fabricated by slip casting. The mechanical properties, fracture morphology, gas permeability, pore size analysis and pore shape factors for the porous Ti compacts were determined for different porosity levels. A decreasing porosity level resulted in less open porosity and gas permeability, reduced pore size, and an increased tensile stress and elongation. The mechanical properties of porous Ti compacts produced by slip casting were comparable with more conventional press and sintered materials at the same porosity levels. Theoretical models for tensile stress and ductility as a function of porosity were examined and incorporated into the results and differences between the theoretical models and experimental results are discussed. The pore shape factor analysis showed that tensile loading would stretch the pores in the compacts to produce more irregular pores, which were acting as linkage sites to allow the propagation of cracks. Additionally, a novel interconnected pore characterisation method using ammonium meta-tungstate solution is presented. By using backscatter scanning electron microscopy, the interconnected pores can be directly observed. 

The packing behaviour and sintering behaviour of Ti compacts fabricated with different particles size distribution were characterised and studied, in terms of porosity, pore size analysis, tensile properties and gas permeability. Two different particles size (avg. 14 μm & avg. 56 μm) of pure Ti hydride-dehydride powder were used in five volume proportions (20:80, 40:60, 60:40, 80:20 & 100:0). A theoretical model predicted that the green density reaches a maximum when the volume fraction of fine particles is 0.35. It was found that although experimental results showed similar behaviour there was no well-defined maximum green density. The sintered compacts showed that an increase in the volume fraction of fine powder particles reduced the porosity, permeability level and pore size, and increased the tensile properties. The relationship between permeability and porosity level was non-linear and this was caused by the differences in pore diameters in the compacts. The capillary tube model was used to discuss the relationship between the permeability, pore diameter and porosity. Using this information, a graded porosity compact was designed and fabricated by slip casting. A future study on this graded porosity compacts is recommended to undertake in more depth.

text: Synthesis, Microstructure and Mechanical Properties of Titanium with Controlled Levels of Porosity Porous titanium (Ti) products have many applications due to their excellent corrosion resistance, high strength-to-weight ratio, high specific surface area, etc. However, the major limitation is the expensive cost of porous Ti products because of the high raw materials costs and the difficulty of processing. The novelty of this research work is concerned with a study of a ceramic casting technique, slip casting, to create porous Ti products and the effect of porosity on the mechanical properties and gas permeability of Ti compacts. 

An optimised Ti slurry was developed from 43 vol.% of Ti powder, 0.3 dw.% of dispersant, 0.8 dw.% of plasticiser and 0.8 dw.% of binder, mixed with a balance of distilled water, which produced a viscosity of 290 cP. It was then poured into a plaster mould to form compacts with a green density of 45%. Thermal debinding was carried out at 320°C with an argon flow for 2 hours, followed by vacuum sintering different samples at 1000°C and 1200°C for 0.5 hours, respectively. The porous sintered compacts had satisfactory tensile strength with some plastic deformation. The increase in oxygen and carbon content during processing was minor. The results from this investigation suggested that slip casting is a potentially low-cost, simple manufacturing route for porous Ti products.

Porous Ti compacts with porosity in the range of 12.3 vol.% to 35.3 vol.% were fabricated by slip casting. The mechanical properties, fracture morphology, gas permeability, pore size analysis and pore shape factors for the porous Ti compacts were determined for different porosity levels. A decreasing porosity level resulted in less open porosity and gas permeability, reduced pore size, and an increased tensile stress and elongation. The mechanical properties of porous Ti compacts produced by slip casting were comparable with more conventional press and sintered materials at the same porosity levels. Theoretical models for tensile stress and ductility as a function of porosity were examined and incorporated into the results and differences between the theoretical models and experimental results are discussed. The pore shape factor analysis showed that tensile loading would stretch the pores in the compacts to produce more irregular pores, which were acting as linkage sites to allow the propagation of cracks. Additionally, a novel interconnected pore characterisation method using ammonium meta-tungstate solution is presented. By using backscatter scanning electron microscopy, the interconnected pores can be directly observed. 

The packing behaviour and sintering behaviour of Ti compacts fabricated with different particles size distribution were characterised and studied, in terms of porosity, pore size analysis, tensile properties and gas permeability. Two different particles size (avg. 14 μm & avg. 56 μm) of pure Ti hydride-dehydride powder were used in five volume proportions (20:80, 40:60, 60:40, 80:20 & 100:0). A theoretical model predicted that the green density reaches a maximum when the volume fraction of fine particles is 0.35. It was found that although experimental results showed similar behaviour there was no well-defined maximum green density. The sintered compacts showed that an increase in the volume fraction of fine powder particles reduced the porosity, permeability level and pore size, and increased the tensile properties. The relationship between permeability and porosity level was non-linear and this was caused by the differences in pore diameters in the compacts. The capillary tube model was used to discuss the relationship between the permeability, pore diameter and porosity. Using this information, a graded porosity compact was designed and fabricated by slip casting. A future study on this graded porosity compacts is recommended to undertake in more depth.

year: 2014

title: Schooling  for  'lesser beings'

authors: Holdom, Jim

subjects: Maori

abstract: Using Edward Said’s notion of ‘lesser beings’, it is argued that the political culture of schooling for Maori was and still is part of a pervasive Western European intellectual climate and culture which has a quite recent history, and which provided powerful support for the notion of Europe possessing a categorical superiority over all other continents, which in turn justified imperialism or neo-colonialism as civilising missions.
Racism and violence were endemic in colonialism and, despite the claimed moral high ground, were endemic in Aotearoa/New Zealand.  War was eulogised in the Native School system more than once.  The rise and demise of the World War II Maori War Organisation is illustrative of the rejection of Maori aspirations.  There were still no Maori in the senior echelons of the Maori Department in 1972.
The Native, later Maori, School system was overtly designed to 'Europeanise' Maori children and therefore Maori society.  Individualism was deeply embedded in English and set-tler thinking, whilst communal, ‘communist’ Maori society was to be destroyed.
The thesis examines images of colonialism, empire and imperialism in fiction and non-fiction, New Zealand and British, for adults and children, and notes the attitudes of think-ers like J S Mill and Darwin, of children’s authors Jules Verne and G H Henty, and of New Zealand author William Satchell.  The images continue, pervasive and endemic, in recent adult novels.  Science also played a role, as did history.
 Ranginui Walker, who is Maori, is the only historian to have written a history of New Zea-land which addressed the issue of waste lands, an issue on which Pakeha historians have a blind spot.  New Zealand encyclopedia do not index ‘waste land’ or ‘confiscation’.  Only two Waikato histories deal adequately, or even accurately, with confiscation, the central episode in the history of the Waikato.  Tourist material is equally illustrative.
The Native Schools section of the Education Department ran the Native Schools like a fiefdom, operating in legislative and regulatory black holes for the first thirty years and for much of the time after that.  Teachers were moved around at will.  
The practice of James H Pope, the first inspector of Native Schools, is closely and critically examined, and negatively assessed.  His official writings were consistently derogatory of Maori, and his decisions in respect of Te Kopua Native School were at times detrimental to the pupils.  Pope was a product of his times.
The Te Kopua record is closely scrutinised, and the practice of the Education Department is frequently found wanting.  It is probable that the establishment of the school was aimed to destabilise King Country Maori, not to benefit the children.  It is a story of Maori co-operation and contribution.
Part Two is a detailed partial biography of Te Kopua, it being argued that until there is a significant corpus of studies of Native Schools a valid history of the Native/Maori School system and of schooling for Maori is not possible

text: Schooling  for  'lesser beings' Using Edward Said’s notion of ‘lesser beings’, it is argued that the political culture of schooling for Maori was and still is part of a pervasive Western European intellectual climate and culture which has a quite recent history, and which provided powerful support for the notion of Europe possessing a categorical superiority over all other continents, which in turn justified imperialism or neo-colonialism as civilising missions.
Racism and violence were endemic in colonialism and, despite the claimed moral high ground, were endemic in Aotearoa/New Zealand.  War was eulogised in the Native School system more than once.  The rise and demise of the World War II Maori War Organisation is illustrative of the rejection of Maori aspirations.  There were still no Maori in the senior echelons of the Maori Department in 1972.
The Native, later Maori, School system was overtly designed to 'Europeanise' Maori children and therefore Maori society.  Individualism was deeply embedded in English and set-tler thinking, whilst communal, ‘communist’ Maori society was to be destroyed.
The thesis examines images of colonialism, empire and imperialism in fiction and non-fiction, New Zealand and British, for adults and children, and notes the attitudes of think-ers like J S Mill and Darwin, of children’s authors Jules Verne and G H Henty, and of New Zealand author William Satchell.  The images continue, pervasive and endemic, in recent adult novels.  Science also played a role, as did history.
 Ranginui Walker, who is Maori, is the only historian to have written a history of New Zea-land which addressed the issue of waste lands, an issue on which Pakeha historians have a blind spot.  New Zealand encyclopedia do not index ‘waste land’ or ‘confiscation’.  Only two Waikato histories deal adequately, or even accurately, with confiscation, the central episode in the history of the Waikato.  Tourist material is equally illustrative.
The Native Schools section of the Education Department ran the Native Schools like a fiefdom, operating in legislative and regulatory black holes for the first thirty years and for much of the time after that.  Teachers were moved around at will.  
The practice of James H Pope, the first inspector of Native Schools, is closely and critically examined, and negatively assessed.  His official writings were consistently derogatory of Maori, and his decisions in respect of Te Kopua Native School were at times detrimental to the pupils.  Pope was a product of his times.
The Te Kopua record is closely scrutinised, and the practice of the Education Department is frequently found wanting.  It is probable that the establishment of the school was aimed to destabilise King Country Maori, not to benefit the children.  It is a story of Maori co-operation and contribution.
Part Two is a detailed partial biography of Te Kopua, it being argued that until there is a significant corpus of studies of Native Schools a valid history of the Native/Maori School system and of schooling for Maori is not possible

year: 1998