title: The effect of surface tension on free surface flow induced by a point sink in a fluid of finite depth

authors: Hocking, Graeme Charles

subjects: mathematics

abstract: Solutions are presented to the problem of steady, axisymmetric flow of an inviscid fluid into a point sink. The fluid is of finite depth and has a free surface. Two numerical schemes, a spectral method and an integral equation approach, are implemented to confirm results for the maximum-flow-rate steady solution for each configuration. The effects of surface tension and sink depth are included and constitute the new component of the work. Surface tension has the effect of increasing the maximum flow rate at which steady-state solutions can exist.

text: The effect of surface tension on free surface flow induced by a point sink in a fluid of finite depth Solutions are presented to the problem of steady, axisymmetric flow of an inviscid fluid into a point sink. The fluid is of finite depth and has a free surface. Two numerical schemes, a spectral method and an integral equation approach, are implemented to confirm results for the maximum-flow-rate steady solution for each configuration. The effects of surface tension and sink depth are included and constitute the new component of the work. Surface tension has the effect of increasing the maximum flow rate at which steady-state solutions can exist.

year: 2017

title: Benthic microbial communities of coastal terrestrial and ice shelf Antarctic meltwater ponds.

authors: Archer, Stephen David James

subjects: Antarctic

abstract: The numerous perennial meltwater ponds distributed throughout Antarctica represent diverse and productive ecosystems central to the ecological functioning of the surrounding ultra oligotrophic environment. The dominant taxa in the pond benthic communities have been well described however, little is known regarding their regional dispersal and local drivers to community structure. The benthic microbial communities of 12 meltwater ponds in the McMurdo Sound of Antarctica were investigated to examine variation between pond microbial communities and their biogeography. Geochemically comparable but geomorphologically distinct ponds were selected from Bratina Island (ice shelf) and Miers Valley (terrestrial) (<40 km between study sites), and community structure within ponds was compared using DNA fingerprinting and pyrosequencing of 16S rRNA gene amplicons. More than 85% of total sequence reads were shared between pooled benthic communities at different locations (OTU0.05), which in combination with favorable prevailing winds suggests aeolian regional distribution. Consistent with previous findings Proteobacteria and Bacteroidetes were the dominant phyla representing over 50% of total sequences; however, a large number of other phyla (21) were also detected in this ecosystem. Although dominant Bacteria were ubiquitous between ponds, site and local selection resulted in heterogeneous community structures and with more than 45% of diversity being pond specific. Potassium was identified as the most significant contributing factor to the cosmopolitan community structure and aluminum to the location unique community based on a BEST analysis (Spearman's correlation coefficient of 0.632 and 0.806, respectively). These results indicate that the microbial communities in meltwater ponds are easily dispersed regionally and that the local geochemical environment drives the ponds community structure.

text: Benthic microbial communities of coastal terrestrial and ice shelf Antarctic meltwater ponds. The numerous perennial meltwater ponds distributed throughout Antarctica represent diverse and productive ecosystems central to the ecological functioning of the surrounding ultra oligotrophic environment. The dominant taxa in the pond benthic communities have been well described however, little is known regarding their regional dispersal and local drivers to community structure. The benthic microbial communities of 12 meltwater ponds in the McMurdo Sound of Antarctica were investigated to examine variation between pond microbial communities and their biogeography. Geochemically comparable but geomorphologically distinct ponds were selected from Bratina Island (ice shelf) and Miers Valley (terrestrial) (<40 km between study sites), and community structure within ponds was compared using DNA fingerprinting and pyrosequencing of 16S rRNA gene amplicons. More than 85% of total sequence reads were shared between pooled benthic communities at different locations (OTU0.05), which in combination with favorable prevailing winds suggests aeolian regional distribution. Consistent with previous findings Proteobacteria and Bacteroidetes were the dominant phyla representing over 50% of total sequences; however, a large number of other phyla (21) were also detected in this ecosystem. Although dominant Bacteria were ubiquitous between ponds, site and local selection resulted in heterogeneous community structures and with more than 45% of diversity being pond specific. Potassium was identified as the most significant contributing factor to the cosmopolitan community structure and aluminum to the location unique community based on a BEST analysis (Spearman's correlation coefficient of 0.632 and 0.806, respectively). These results indicate that the microbial communities in meltwater ponds are easily dispersed regionally and that the local geochemical environment drives the ponds community structure.

year: 2015

title: Arnold Manaaki Wilson: Te Awakaunua

authors: Te Awekotuku, Ngahuia

subjects: Arnold Manaaki Wilson

abstract: Arnold Manaaki Wilson was born in 1928, in Ruatoki, a community which nestles beneath the misty Taiarahia hills, following the curves of the Ohinemataroa river valley – known to others as of his tuhoe people. They know him there as Te Wakaunua, after a provocative late 19th century political visionary. From Such radical Tuhoe ideas fused with the sculptural genius of his father, a renowned carver of the art-making Ngati Tarawhai of Te Arawa, Arnold Wilson emerged.

text: Arnold Manaaki Wilson: Te Awakaunua Arnold Manaaki Wilson was born in 1928, in Ruatoki, a community which nestles beneath the misty Taiarahia hills, following the curves of the Ohinemataroa river valley – known to others as of his tuhoe people. They know him there as Te Wakaunua, after a provocative late 19th century political visionary. From Such radical Tuhoe ideas fused with the sculptural genius of his father, a renowned carver of the art-making Ngati Tarawhai of Te Arawa, Arnold Wilson emerged.

year: 2008