title: Superantigen architecture: Functional decoration on a conserved scaffold

authors: Arcus, Vickery L.

subjects: biology

abstract: A defining and consistent feature of the bacterial superantigens from Staphylococcus aureus and Streptococcus pyogenes is their strongly conserved three-dimensional structure. Structural studies to date show that the array of more than 280 amino acid sequences known for superantigens (SAgs) and staphylococcal superantigen-like (SSL) proteins all have the same fold-a structure in which the same three-dimensional arrangement of α-helices and β-sheets is traced by each amino acid sequence, with the same topology (for recent reviews, see references 29 and 43). A typical SAg structure comprises two domains-an N-terminal β -barrel domain called an OB-fold (4, 25) and a C-terminal β-grasp domain in which a long α-helix packs on to a mixed parallel and antiparallel β-sheet. These two domains are traversed by an α-helix that lies at the N terminus of the protein and packs against the β-grasp domain, thus linking the N- and C-terminal domains.

text: Superantigen architecture: Functional decoration on a conserved scaffold A defining and consistent feature of the bacterial superantigens from Staphylococcus aureus and Streptococcus pyogenes is their strongly conserved three-dimensional structure. Structural studies to date show that the array of more than 280 amino acid sequences known for superantigens (SAgs) and staphylococcal superantigen-like (SSL) proteins all have the same fold-a structure in which the same three-dimensional arrangement of α-helices and β-sheets is traced by each amino acid sequence, with the same topology (for recent reviews, see references 29 and 43). A typical SAg structure comprises two domains-an N-terminal β -barrel domain called an OB-fold (4, 25) and a C-terminal β-grasp domain in which a long α-helix packs on to a mixed parallel and antiparallel β-sheet. These two domains are traversed by an α-helix that lies at the N terminus of the protein and packs against the β-grasp domain, thus linking the N- and C-terminal domains.

year: 2007

title: In-kernel passive measurement of the performance impact of hidden terminals in 802.11 wireless networks

authors: Raynel, Scott McKenzie

subjects: computer science

abstract: The negative performance impact of the presence of hidden terminals in wireless networks has been well know for decades. Despite much research in the area, many deployed networks continue to suffer a performance penalty because of hidden terminals. Ad hoc wireless networks are particularly susceptible to hidden terminal collisions because there are fewer opportunities to plan the network in a way that avoids or reduces the number of hidden terminals. Measuring the presence of hidden terminals and the impact they are having on performance is difficult, especially in a network of many nodes. Without such measurements, the users and operators of wireless networks can not tell if performance problems are caused by hidden terminals or some other problem. We introduce new methodology that can detect the presence of hidden terminals and estimate the performance impact they are causing. The methodology requires no additional hardware and is suitable for wide scale deployment and long term operation. The approach is based on in-kernel instrumentation of the wireless network stack. The design, implementation, and testing of the approach are covered. Results from in-lab testing and the measurement of a live commercial 802.11 network are also presented, including a case study where performance was significantly improved.

text: In-kernel passive measurement of the performance impact of hidden terminals in 802.11 wireless networks The negative performance impact of the presence of hidden terminals in wireless networks has been well know for decades. Despite much research in the area, many deployed networks continue to suffer a performance penalty because of hidden terminals. Ad hoc wireless networks are particularly susceptible to hidden terminal collisions because there are fewer opportunities to plan the network in a way that avoids or reduces the number of hidden terminals. Measuring the presence of hidden terminals and the impact they are having on performance is difficult, especially in a network of many nodes. Without such measurements, the users and operators of wireless networks can not tell if performance problems are caused by hidden terminals or some other problem. We introduce new methodology that can detect the presence of hidden terminals and estimate the performance impact they are causing. The methodology requires no additional hardware and is suitable for wide scale deployment and long term operation. The approach is based on in-kernel instrumentation of the wireless network stack. The design, implementation, and testing of the approach are covered. Results from in-lab testing and the measurement of a live commercial 802.11 network are also presented, including a case study where performance was significantly improved.

year: 2011

title: Indigenous Psychology in Aotearoa: Realising Māori Aspirations

authors: Levy, Michelle Patricia

subjects: Maori

abstract: Indigenous psychology in Aotearoa positions the aspirations of Māori as central.  The aim of this thesis is to describe and contribute to the development of a psychological discipline which is relevant and of benefit for Māori communities.  Part One sets the scene in Aotearoa, examining the relationship between Māori development and psychology.  Part Two explores the indigenous psychology literature base, identifying strategies which may be relevant to Aotearoa.  The key themes of context, critical mass, and mechanisms to support indigenous psychology development are identified as being relevant to Aotearoa.  Part Three explores indigenous psychology development in Aotearoa.  Data from a range of sources is qualitatively analysed to develop five themes which describe the current status of Māori development in psychology, the importance of the critical mass and the notion of collective responsibility.  Part Four, drawing from the analysis in Parts One, Two and Three, identifies 'reaching the point of irreversible change' as the next phase of indigenous psychology development in Aotearoa.  This is the point at which indigenous psychology development becomes self-sustaining.  

The point at which irreversible change occurs is when: Māori knowledge bases are a legitimate part of psychology in Aotearoa; resistance to the legitimacy of Māori knowledge bases in psychology is not a characteristic of our landscape; environments supportive of indigenous psychology development are commonplace; and responsibility for contributing to indigenous psychology development is shared among and sustained by the collective capacity of the Leaders and Producers.  Consolidation, the process by which multiple and interrelated pathways are connected to form a unified whole, is fundamental to reaching the point of irreversible change.  An original interactional framework for consolidation is proposed.  This framework is based on two key consolidating mechanisms: a working description of Kaupapa Māori Psychologies; and a Kaupapa Māori Psychologies Research and Training Centre.  Psychologies relevant and of benefit to Māori communities which contribute to the realisation of Māori aspirations are the cornerstones, with all elements of the framework leading back into this fundamental foundation.

text: Indigenous Psychology in Aotearoa: Realising Māori Aspirations Indigenous psychology in Aotearoa positions the aspirations of Māori as central.  The aim of this thesis is to describe and contribute to the development of a psychological discipline which is relevant and of benefit for Māori communities.  Part One sets the scene in Aotearoa, examining the relationship between Māori development and psychology.  Part Two explores the indigenous psychology literature base, identifying strategies which may be relevant to Aotearoa.  The key themes of context, critical mass, and mechanisms to support indigenous psychology development are identified as being relevant to Aotearoa.  Part Three explores indigenous psychology development in Aotearoa.  Data from a range of sources is qualitatively analysed to develop five themes which describe the current status of Māori development in psychology, the importance of the critical mass and the notion of collective responsibility.  Part Four, drawing from the analysis in Parts One, Two and Three, identifies 'reaching the point of irreversible change' as the next phase of indigenous psychology development in Aotearoa.  This is the point at which indigenous psychology development becomes self-sustaining.  

The point at which irreversible change occurs is when: Māori knowledge bases are a legitimate part of psychology in Aotearoa; resistance to the legitimacy of Māori knowledge bases in psychology is not a characteristic of our landscape; environments supportive of indigenous psychology development are commonplace; and responsibility for contributing to indigenous psychology development is shared among and sustained by the collective capacity of the Leaders and Producers.  Consolidation, the process by which multiple and interrelated pathways are connected to form a unified whole, is fundamental to reaching the point of irreversible change.  An original interactional framework for consolidation is proposed.  This framework is based on two key consolidating mechanisms: a working description of Kaupapa Māori Psychologies; and a Kaupapa Māori Psychologies Research and Training Centre.  Psychologies relevant and of benefit to Māori communities which contribute to the realisation of Māori aspirations are the cornerstones, with all elements of the framework leading back into this fundamental foundation.

year: 2007