Resting metabolic rates of two orbweb spiders: A first approach to evolutionary success of ecribellate spiders

Spiders are considered conservative with regard to their resting metabolic rate, presenting the same allometric relation with body mass as the majority of land-arthropods. Nevertheless, web-building is thought to have a great impact on the energetic metabolism, and any modification that affects this complex behavior is expected to have an impact over the daily energetic budget. We analyzed the possibility of the presence of the cribellum having an effect on the allometric relation between resting metabolic rate and body mass for an ecribellate species (Zosis geniculata) and a cribellate one (Metazygia rogenhoferi), and employed a model selection approach to test if these species had the same allometric relationship as other land-arthropods. Our results show that M. rogenhoferi has a higher resting metabolic rate, while Z. geniculata fitted the allometric prediction for land arthropods. This indicates that the absence of the cribellum is associated with a higher resting metabolic rate, thus explaining the higher promptness to activity found for the ecribellate species. If our result proves to be a general rule among spiders, the radiation of Araneoidea could be connected to a more energy-consuming life style. Thus, we briefly outline an alternative model of diversification of Araneoidea that accounts for this possibility. (C) 2011 Elsevier Ltd. All rights reserved.

Herbivory in Spiders: The Importance of Pollen for Orb-Weavers

Orb-weaving spiders (Araneidae) are commonly regarded as generalist insect predators but resources provided by plants such as pollen may be an important dietary supplementation. Their webs snare insect prey, but can also trap aerial plankton like pollen and fungal spores. When recycling their orb webs, the spiders may therefore also feed on adhering pollen grains or fungal spores via extraoral digestion. In this study we measured stable isotope ratios in the bodies of two araneid species (Aculepeira ceropegia and Araneus diadematus), their potential prey and pollen to determine the relative contribution of pollen to their diet. We found that about 25% of juvenile orb-weaving spiders’ diet consisted of pollen, the other 75% of flying insects, mainly small dipterans and hymenopterans. The pollen grains in our study were too large to be taken up accidentally by the spiders and had first to be digested extraorally by enzymes in an active act of consumption. Therefore, pollen can be seen as a substantial component of the spiders’ diet. This finding suggests that these spiders need to be classified as omnivores rather than pure carnivores.

The role of salt and shear on the storage and assembly of spider silk proteins

Major ampullate silk fibers of orb web-weaving spiders have impressive mechanical properties due to the fact that the underlying proteins partially fold into helical/amorphous structures, yielding relatively elastic matrices that are toughened by anisotropic nanoparticulate inclusions (formed from stacks of beta-sheets of the same proteins). In vivo the transition from soluble protein to solid fibers involves a combination of chemical and mechanical stimuli (such as ion exchange, extraction of water and shear forces). Here we elucidate the effects of such stimuli on the in vitro aggregation of engineered and recombinantly produced major ampullate silk-like proteins (focusing on structure-function relationships with respect to their primary structures), and discuss their relevance to the storage and assembly of spider silk proteins in vivo. (C) 2009 Elsevier Inc. All rights reserved.

Tenacity and silk investment of two orb weavers: considerations about diversification of the Araneoidea

Orbiculariae consists of two major clades: the cribellate Deinopidea and the much more diverse ecribellate Araneoidea. It has been hypothesized that the higher diversity of Araneoidea is a consequence of the superiority of the viscid orb web. However, this explanation seems incomplete: for example, cribellate silk may perform better than viscid silk in some contexts. Here, we consider the hypothesis that the diversification of Araneoidea was facilitated by changes in microhabitat occupation behavior due to the cheaper viscid orb web. In the present work we investigate the idea that the reduction in site tenacity caused by the emergence of the viscid orb web has led to an increase in the exploration of different resources and to a greater diversification of the Arancoidea through the evolutionary time. To test this idea, we evaluated the response of one cribellate orb web spider (Zosis geniculata Olivier 1789, Uloboridae) and one ecribellate orb web spider (Metazygia rogenhoferi Keyserling 1878, Arancidae) to abrupt prey absence. The changes in site tenacity and the day-to-day investment in web silk were evaluated. Spiders with three-dimensional webs tend to exhibit greater site tenacity than spiders making orb webs. Zosis geniculata and M. rogenhoferi show similar site tenacity when prey is ample. When prey is unavailable, the tenacity of the cribellate species increases while the tenacity of the ecribellate remains unchanged, and the silk investment of both species decreases. However, this decrease in silk investment is more extensive in Z. geniculata. These results coincide with the idea that a less costly ecribellate orb web leads to a lower tenacity and suggest that more frequent microhabitat abandonment in a context of insect radiation (Neiptera) leads to more diverse and opportunistic exploration of microhabitats that, in the long term, may be one explanation for the greater Araneoidea diversification.

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Imperfect assessment and limited information preclude optimal strategies in male-male fights in the orb-weaving spider Metellina mengei

Agonistic behaviour between male orb-web spiders Metellina mengei competing for access to female webs was examined in field experiments to test the major predictions of game theory. Winners of fights were significantly larger than losers, particularly with respect to the length of the first pair of legs, which are sexually dimorphic in this species and used extensively in agonistic encounters. The size of the winning male had no influence on contest intensity or duration, and neither did relative size. However, fight intensity and duration were both positively correlated with the size of the losing male. Resident males won significantly more contests than intruders. Winning intruders were significantly larger than winning residents and it was these winning intruders that tended to produce the longer fights. Female weight and hence reproductive value had a marked influence on fight intensity and duration of fights won by the intruder but not those won by the resident. This indicates that only the resident obtains information about the female. These data are discussed with reference to the discrepancy with theory and a failure of some contestants to obtain information on resource value and relative contestant size necessary to optimize fight strategy.

Weaving yarns : the lived experience of Indigenous Australians with adult-onset disability in Brisbane

Indigenous Australians have lower levels of health than mainstream Australians and (as far as statistics are able to indicate) higher levels of disability, yet there is little information on Indigenous social and cultural constructions of disability or the Indigenous experience of disability. This research seeks to address these gaps by using an ethnographic approach, couched within a critical medical anthropology (CMA) framework and using the “three bodies” approach, to study the lived experience of urban Indigenous people with an adult-onset disability. The research approach takes account of the debate about the legitimacy of research into Indigenous Australians, Foucault‟s governmentality, and the arguments for different models of disability. The possibility of a cultural model of disability is raised. After a series of initial interviews with contacts who were primarily service providers, more detailed ethnographic research was conducted with three Indigenous women in their homes and with four groups of Indigenous women and men at an Indigenous respite centre. The research involved multiple visits over a period extending more than two years, and the establishment of relationships with all participants. An iterative inductive approach utilising constant comparison (i.e. a form of grounded theory) was adopted, enabling the generation and testing of working hypotheses. The findings point to the lack of an Indigenous construct of disability, related to the holistic construction of health among Indigenous Australians. Shame emerges as a factor which affects the way that Indigenous Australians respond to disability, and which operates in apparent contradiction to expectations of community support. Aspects of shame relate to governmentality, suggesting that self-disciplinary mechanisms have been taken up and support the more obvious exertion of government power. A key finding is the strength of Indigenous identity above and beyond other forms of identification, e.g. as a person with a disability, expressed in forms of resistance by individuals and service providers to the categories and procedures of the mainstream. The implications of a holistic construction of health are discussed in relation to the use of CMA, the interpretation of the “three bodies”, governmentality and resistance. The explanatory value of the concept of sympatricity is discussed, as is the potential value of a cultural model of disability which takes into account the cultural politics of a defiant Indigenous identity.

Boundary weaving : the social structure and processes of organizational boundaries

Boundaries are an important field of study because they mediate almost every aspect of organizational life. They are becoming increasingly more important as organizations change more frequently and yet, despite the endemic use of the boundary metaphor in common organizational parlance, they are poorly understood. Organizational boundaries are under-theorized and researchers in related fields often simply assume their existence, without defining them. The literature on organizational boundaries is fragmented with no unifying theoretical basis. As a result, when it is recognized that an organizational boundary is "dysfunctional". there is little recourse to models on which to base remediating action. This research sets out to develop just such a theoretical model and is guided by the general question: "What is the nature of organizational boundaries?" It is argued that organizational boundaries can be conceptualised through elements of both social structure and of social process. Elements of structure include objects, coupling, properties and identity. Social processes include objectification, identification, interaction and emergence. All of these elements are integrated by a core category, or basic social process, called boundary weaving. An organizational boundary is a complex system of objects and emergent properties that are woven together by people as they interact together, objectifying the world around them, identifying with these objects and creating couplings of varying strength and polarity as well as their own fragmented identity. Organizational boundaries are characterised by the multiplicity of interconnections, a particular domain of objects, varying levels of embodiment and patterns of interaction. The theory developed in this research emerged from an exploratory, qualitative research design employing grounded theory methodology. The field data was collected from the training headquarters of the New Zealand Army using semi-structured interviews and follow up observations. The unit of analysis is an organizational boundary. Only one research context was used because of the richness and multiplicity of organizational boundaries that were present. The model arose, grounded in the data collected, through a process of theoretical memoing and constant comparative analysis. Academic literature was used as a source of data to aid theory development and the saturation of some central categories. The final theory is classified as middle range, being substantive rather than formal, and is generalizable across medium to large organizations in low-context societies. The main limitation of the research arose from the breadth of the research with multiple lines of inquiry spanning several academic disciplines, with some relevant areas such as the role of identity and complexity being addressed at a necessarily high level. The organizational boundary theory developed by this research replaces the typology approaches, typical of previous theory on organizational boundaries and reconceptualises the nature of groups in organizations as well as the role of "boundary spanners". It also has implications for any theory that relies on the concept of boundaries, such as general systems theory. The main contribution of this research is the development of a holistic model of organizational boundaries including an explanation of the multiplicity of boundaries . no organization has a single definable boundary. A significant aspect of this contribution is the integration of aspects of complexity theory and identity theory to explain the emergence of higher-order properties of organizational boundaries and of organizational identity. The core category of "boundary weaving". is a powerful new metaphor that significantly reconceptualises the way organizational boundaries may be understood in organizations. It invokes secondary metaphors such as the weaving of an organization's "boundary fabric". and provides managers with other metaphorical perspectives, such as the management of boundary friction, boundary tension, boundary permeability and boundary stability. Opportunities for future research reside in formalising and testing the theory as well as developing analytical tools that would enable managers in organizations to apply the theory in practice.

Less but more : weaving disparate disciplines together for learners to construct their own knowledge

This paper reports on a Professional Learning Program conducted in China with 140 general technology teachers. It aimed to integrate robotics technology across and within the disciplines of science, technology, engineering and mathematics. With the help of university facilitators teachers developed General Technology lessons that seamlessly integrated with rich learning content across disciplines. Teachers engaged in seminars and workshops, which provided the opportunities for them to actively couch sound principles of learning in their daily work. They gained first-hand experience in applying an aligned system of assessments, standards and quality learning experiences geared to the needs of each student. Teachers worked collaboratively in teams to create inquiry, design and collaborative learning activities that aligned with their curriculum and which dealt with real world problems, issues and challenges. They continually discussed and reflected deeply on the activities and shared the newly developed resources online with teachers across the entire country. It is evident from the preliminary analysis of data that teachers are beginning to apply rich pedagogical practices and are becoming ‘adaptive’ in their approach when using LEGO® robotic tools to design, redesign, create and re-create learning activities for their students.

Dynamic weaving of aspects for business process management systems

Reducing complexity in Information Systems is a main concern in both research and industry. One strategy for reducing complexity is separation of concerns. This strategy advocates separating various concerns, like security and privacy, from the main concern. It results in less complex, easily maintainable, and more reusable Information Systems. Separation of concerns is addressed through the Aspect Oriented paradigm. This paradigm has been well researched and implemented in programming, where languages such as AspectJ have been developed. However, the rsearch on aspect orientation for Business Process Management is still at its beginning. While some efforts have been made proposing Aspect Oriented Business Process Modelling, it has not yet been investigated how to enact such process models in a Workflow Management System. In this paper, we define a set of requirements that specifies the execution of aspect oriented business process models. We create a Coloured Petri Net specification for the semantics of so-called Aspect Service that fulfils these requirements. Such a service extends the capability of a Workflow Management System with support for execution of aspect oriented business process models. The design specification of the Aspect Service is also inspected through state space analysis.

Weaving the past into the present : Indigenous stories of education across generations

In Queensland, there is little research that speaks to the historical experiences of schooling. Aboriginal education remains a part of the silenced history of Aboriginal people. This thesis presents stories of schooling from Aboriginal people across three generations of adult storytellers. Elders, grandparents, and young parents involved in an early childhood urban playgroup were included. Stories from the children attending the playgroup were also welcomed. The research methodology involved narrative storywork. This is culturally appropriate because Aboriginal stories connect the past with the present. The conceptual framework for the research draws on decolonising theory. Typically, reports of Aboriginal schooling and outcomes position Aboriginal families and children within a deficit discourse. The issues and challenges faced by urban Murri families who have young children or children in school are largely unknown. This research allowed Aboriginal families to participate in an engaged dialogue about their childhood and offered opportunities to tell their stories of education. Key research questions were: What was the reality of school for different generations of Indigenous people? What beliefs and values are held about mainstream education for Indigenous children? What ideas are communicated about school across generations? Narratives from five elders, five grandparents, and five (urban) mothers of young Indigenous children are presented. The elders offer testimony on their recollected experiences of schooling in a mission, a Yumba school (fringe-dwellers’ camp), and country schools. Their stories also speak to the need to pass as non-indigenous and act as “white”. The next generation of storytellers are the grandparents and they speak to their lives as “stolen children”. The final story tellers are the Murri parents. They speak to the current and recent past of education, as well as their family experiences as they parent young children who are about to enter school or who are in the early years of school.