title: Effect of a physical disturbance event on deep-sea nematode community structure and ecosystem function

authors: Leduc, Daniel

subjects: biodiversity

abstract: Numerous studies have been conducted on the effect of physical disturbance on shallow water benthic communities, but there is a paucity of data from deep-sea environments. We conducted a laboratory experiment using undisturbed sediment cores from Chatham Rise (water depth =345 m), Southwest Pacific, to investigate the effects of a physical disturbance event (resuspension of surface sediments) on sediment characteristics (sediment grain size, pigment content), nematode community attributes (abundance, diversity, community structure) and ecosystem function (sediment community oxygen consumption (SCOC)) over a period of 9 days. Disturbance did not have any noticeable impact on sediment characteristics, SCOC, or nematode species richness, but led to changes in vertical distribution patterns and shifts in nematode community structure. The magnitude of disturbance-related effects was, however, much smaller than the effect of sediment depth (0-1, 1-3, and 3-5 cm), and the main impact of disturbance on nematode vertical distribution patterns and community structure appeared to be related to a vertical re-shuffling of nematodes in the sediments rather than mortality. We did not observe substantial increases in the abundance of nematode genera generally regarded as disturbance-tolerant, such as Sabatieria. The worst-affected species belongs to the Stilbonematinae, a group of typically long and slender nematodes that may be easily damaged by physical disturbance. The limited impact of physical disturbance on benthic community structure and function suggests that the Chatham Rise nematode community is relatively resilient to sediment resuspension. This resilience may have arisen from frequent exposure to disturbance in the field (e.g., from strong currents), or may be a more widespread feature of nematode communities.

text: Effect of a physical disturbance event on deep-sea nematode community structure and ecosystem function Numerous studies have been conducted on the effect of physical disturbance on shallow water benthic communities, but there is a paucity of data from deep-sea environments. We conducted a laboratory experiment using undisturbed sediment cores from Chatham Rise (water depth =345 m), Southwest Pacific, to investigate the effects of a physical disturbance event (resuspension of surface sediments) on sediment characteristics (sediment grain size, pigment content), nematode community attributes (abundance, diversity, community structure) and ecosystem function (sediment community oxygen consumption (SCOC)) over a period of 9 days. Disturbance did not have any noticeable impact on sediment characteristics, SCOC, or nematode species richness, but led to changes in vertical distribution patterns and shifts in nematode community structure. The magnitude of disturbance-related effects was, however, much smaller than the effect of sediment depth (0-1, 1-3, and 3-5 cm), and the main impact of disturbance on nematode vertical distribution patterns and community structure appeared to be related to a vertical re-shuffling of nematodes in the sediments rather than mortality. We did not observe substantial increases in the abundance of nematode genera generally regarded as disturbance-tolerant, such as Sabatieria. The worst-affected species belongs to the Stilbonematinae, a group of typically long and slender nematodes that may be easily damaged by physical disturbance. The limited impact of physical disturbance on benthic community structure and function suggests that the Chatham Rise nematode community is relatively resilient to sediment resuspension. This resilience may have arisen from frequent exposure to disturbance in the field (e.g., from strong currents), or may be a more widespread feature of nematode communities.

year: 2013

title: Understanding the properties of low-cost iron-containing powder metallurgy titanium alloys

authors: Bolzoni, Leandro

abstract: The high production costs of titanium in comparison to other structural metals is the main limiting factor for the wide employment of titanium. Cost reduction can be addressed considering creative fabrication methods and/or formulating new chemical compositions. In this work the fabrication of low-cost iron-containing powder metallurgy titanium alloys is studied by using a spherical 85Fe/15Ni powder whose small particle size and spherical morphology favours both the densification of the material and the diffusion of the alloying elements. The designed composition are obtained by the blending elemental approach and processed by means of the conventional powder metallurgy route. The high vacuum sintered α + β alloys show homogeneous microstructure and the formation of brittle intermetallic phases is prevented as checked by XRD and DTA analysis. Similar physical and mechanical behaviour to wrought-equivalent structural titanium alloys is obtained for these new low-cost alloys which, therefore, are potential materials for cheaper structural titanium components.

text: Understanding the properties of low-cost iron-containing powder metallurgy titanium alloys The high production costs of titanium in comparison to other structural metals is the main limiting factor for the wide employment of titanium. Cost reduction can be addressed considering creative fabrication methods and/or formulating new chemical compositions. In this work the fabrication of low-cost iron-containing powder metallurgy titanium alloys is studied by using a spherical 85Fe/15Ni powder whose small particle size and spherical morphology favours both the densification of the material and the diffusion of the alloying elements. The designed composition are obtained by the blending elemental approach and processed by means of the conventional powder metallurgy route. The high vacuum sintered α + β alloys show homogeneous microstructure and the formation of brittle intermetallic phases is prevented as checked by XRD and DTA analysis. Similar physical and mechanical behaviour to wrought-equivalent structural titanium alloys is obtained for these new low-cost alloys which, therefore, are potential materials for cheaper structural titanium components.

year: 2016-11-15

title: What do we know about the intersection of being blind and being Māori in Aotearoa New Zealand? Taking an applied community psychology approach to a systematic review of the published literature

authors: Graham, Rebekah Sarah

subjects: Disability

abstract: Self-determination and dignity are guaranteed rights for disabled persons under the United Nations Convention on the Rights of Persons with Disabilities. However, such rights have been slow to eventuate for Maori (Indigenous people of Aotearoa New Zealand). This paper brings together systematic fashion publications that currently exist regarding blindness and Maori, centring throughout Maori understandings of disability and blindness. We employed a structured approach alongside PRISMA protocols and reflexive dialogue. Included publications were quantitative data reviews, surveys, qualitative studies, literature reviews, and works of fiction. For our analysis, we formulated a matrix that drew from Kaupapa Maori, applied community psychology, and disability rights literature. This meant we made explicit where research practices included—and excluded—self-determination, democratic participation, and inclusion of both disabled and Maori. Our review highlights inconsistency across disciplines regarding self-determination and democratic participation by both Maori and disabled key stakeholders. Our approach can be utilised across disciplines as a tool for considering the ways in which researchers uphold Indigenous self-determination, disability rights, and data sovereignty. Please refer to the Supplementary Material section to find this article's Community and Social Impact Statement.

text: What do we know about the intersection of being blind and being Māori in Aotearoa New Zealand? Taking an applied community psychology approach to a systematic review of the published literature Self-determination and dignity are guaranteed rights for disabled persons under the United Nations Convention on the Rights of Persons with Disabilities. However, such rights have been slow to eventuate for Maori (Indigenous people of Aotearoa New Zealand). This paper brings together systematic fashion publications that currently exist regarding blindness and Maori, centring throughout Maori understandings of disability and blindness. We employed a structured approach alongside PRISMA protocols and reflexive dialogue. Included publications were quantitative data reviews, surveys, qualitative studies, literature reviews, and works of fiction. For our analysis, we formulated a matrix that drew from Kaupapa Maori, applied community psychology, and disability rights literature. This meant we made explicit where research practices included—and excluded—self-determination, democratic participation, and inclusion of both disabled and Maori. Our review highlights inconsistency across disciplines regarding self-determination and democratic participation by both Maori and disabled key stakeholders. Our approach can be utilised across disciplines as a tool for considering the ways in which researchers uphold Indigenous self-determination, disability rights, and data sovereignty. Please refer to the Supplementary Material section to find this article's Community and Social Impact Statement.

year: 2023