920 resultados para antipredator defence
Resumo:
Predation is an important source of mortality for most aquatic animals. Thus, the ability to avoid being eaten brings substantial fitness benefits to individuals. Predator detection abilities and antipredator behaviour were examined in various planktivores, i.e. the littoral mysids Neomysis integer and Praunus flexuosus, three-spined stickleback Gasterosteus aculeatus larvae, pelagic mysids Mysis mixta and M. relicta, and the predatory cladoceran Cercopagis pengoi, with cues from their respective predators European perch Perca fluviatilis and Baltic herring Clupea harengus membras. The use of different aquatic macrophytes as predation refuges by the littoral planktivores was also examined. All pelagic planktivores and stickleback larvae were able to detect the presence of their predator by chemical cues alone. The littoral mysids N. integer and P. flexuosus responded only when chemical and visual predator cues were combined. The responses of stickleback larvae were stronger to the combined cues than the chemical cue alone. A common antipredator behaviour in all of the planktivores studied was decreased ingestion rate in response to predator cues. N. integer and stickleback larvae also decreased their swimming activity. Pelagic mysids and C. pengoi altered their prey selectivity patterns in response to predator cues. The effects of predator cues on the swarming behaviour of N. integer were examined. Swarming brings clear antipredator advantages to N. integer, since when they feed in a swarm, they do not significantly decrease their feeding rate. However, the swarming behaviour of N. integer was not affected by predation risk, but was instead a fixed strategy. Despite the presence or absence of predator cues, N. integer individuals attempted to associate with a swarm and preferred larger to smaller swarms. In studies with aquatic macrophytes, stickleback larvae and P. flexuosus utilized vegetation as a predation refuge, spending more time within vegetation when under predation threat. The two macroalgal species studied, bladderwrack Fucus vesiculosus and stonewort Chara tomentosa, were preferred by P. flexuosus, whereas Eurasian watermilfoil Myriophyllum spicatum was strongly avoided by N. integer and stickleback larvae. In fact, when in dense patches in aquaria, M. spicatum caused acute and high mortality (> 70%) in littoral mysids, but not in sticklebacks, whereas C. tomentosa and northern watermilfoil M. sibiricum did not. In contrast, only 2-4% mortality in N. integer was observed with intact and broken stems of M. spicatum in field experiments. The distribution of littoral mysids in different vegetations, however, suggests that N. integer avoids areas vegetated by M. spicatum.
Resumo:
Non-resident workforces experience high labour turnover, which has an impact on organisational operations and affects worker satisfaction and, in turn, partners’ ability to cope with work-related absences. Research suggests that partner satisfaction may be increased by providing a range of support services, which include professional, practical, and social support. A search was conducted to identify support available for resources and health-industry non-resident workers. These were compared to the supports available to families of deployed defence personnel. They were used to compare and contrast the spread available for each industry. The resources industry primarily provided social support, and lacked an inclusion of professional and practical supports. Health-professional support services were largely directed towards extended locum support, rather than to Fly-In Fly-Out workers. Improving sources of support which parallel support provided to the Australian Defence Force is suggested as a way to increase partner satisfaction. The implications are to understand the level of uptake, perceived importance, and utilisation of such support services.
Resumo:
This research is connected with an education development project for the four-year-long officer education program at the National Defence University. In this curriculum physics was studied in two alternative course plans namely scientific and general. Observations connected to the later one e.g. student feedback and learning outcome gave indications that action was needed to support the course. The reform work was focused on the production of aligned course related instructional material. The learning material project produced a customized textbook set for the students of the general basic physics course. The research adapts phases that are typical in Design Based Research (DBR). The research analyses the feature requirements for physics textbook aimed at a specific sector and frames supporting instructional material development, and summarizes the experiences gained in the learning material project when the selected frames have been applied. The quality of instructional material is an essential part of qualified teaching. The goal of instructional material customization is to increase the product's customer centric nature and to enhance its function as a support media for the learning process. Textbooks are still one of the core elements in physics teaching. The idea of a textbook will remain but the form and appearance may change according to the prevailing technology. The work deals with substance connected frames (demands of a physics textbook according to the PER-viewpoint, quality thinking in educational material development), frames of university pedagogy and instructional material production processes. A wide knowledge and understanding of different frames are useful in development work, if they are to be utilized to aid inspiration without limiting new reasoning and new kinds of models. Applying customization even in the frame utilization supports creative and situation aware design and diminishes the gap between theory and practice. Generally, physics teachers produce their own supplementary instructional material. Even though customization thinking is not unknown the threshold to produce an entire textbook might be high. Even though the observations here are from the general physics course at the NDU, the research gives tools also for development in other discipline related educational contexts. This research is an example of an instructional material development work together the questions it uncovers, and presents thoughts when textbook customization is rewarding. At the same time, the research aims to further creative customization thinking in instruction and development. Key words: Physics textbook, PER (Physics Education Research), Instructional quality, Customization, Creativity
Resumo:
In Finland the organising of defence is undergoing vast restructuring. Recent legislation has redefined the central tasks of the Finnish Defence Forces. At the same time, international security cooperation, economic pressures and new administrative paradigms have steered the military towards new ways of organising. National defence is not just politics and principles; to a large extent it is also enacted in day-to-day life in organisations. The lens through which these realities of defence are analysed in this study is gender. How is the security sector – and national defence as part of it – organised in the changing security environment? What is the new division of labour between different societal actors in the face of security challenges? What happens ‘at work’ within the military and the defence sector more broadly? How does gender affect the way in which defence is organised and understood, and how do the changes in the organising of security affect gender relations? The thesis searches for answers to these questions in the context of two organisational settings in the male-dominated defence sector. The case study on a Finnish peacekeeping unit in the Balkans opens a critical view on men’s social practices and the everyday life of crisis management organisations. In the second case study, reorganising of provisioning in the Finnish Defence Forces turns out to be a complicated process where different power relations and social divisions intermingle. Tallberg’s extensive ethnographic fieldwork in the two focal organisations has produced a detailed set of data that lays the basis for critical analysis and policy development in terms of defence organising, cooperation around peace and security issues, and gender equality in organisations. Observations and results are provided for understanding social networks, militarisation, authority relations, care, public-private partnerships, personnel policies, career planning, and humour.
Resumo:
Defending a large social insect colony containing several thousands of workers requires the simultaneous action of many individuals. Ideally this action involves communication between the workers, enabling coordinated action and a fast response. The Asian dwarf honeybee, Apis florea, is a small honeybee with an open nesting habit and a comparatively small colony size, features that leave them particularly exposed to predators. We describe here a novel defence response of these bees in which the emission of an initial warning signal from one individual (“piping”) is followed 0.3 to 0.7 seconds later by a general response from a large number of bees (“hissing”). Piping is audible to the human ear, with a fundamental frequency of 384 ± 31Hz and lasting for 0.82 ± 0.35 seconds. Hissing is a broad band, noisy signal, clearly audible to the human observer and produced by slight but visible movements of the bees' wings. Hissing begins in individuals close to the piping bee, spreads rapidly to neighbours and results in an impressive coordinated crescendo occasionally involving the entire colony. Piping and hissing are accompanied by a marked decrease, or even cessation, of worker activities such as forager dancing and departures from the colony. We show that whereas hissing of the colony can be elicited without piping, the sequential and correlated piping and hissing response is specific to the presence of potential predators close to the colony. We suggest that the combined audio-visual effect of the hissing might deter small predators, while the cessation of flight activity could decrease the risk of predation by birds and insects which prey selectively on flying bees.
Resumo:
There has been a perception of increasing river channel instability in north west rivers and the River Lune in particular in recent decades. This has been attributed variously to: (a) long-term trends in precipitation-runoff regime; (b) changes in land-use such as moor-draining and sub-soil draining such that the river is more flashy than previously, and (c) a change in the magnitude-frequency relationships of flow such that high discharges are occurring with increased frequency. Resources are available in the form of rainfall and runoff records, archived information on channel planform, land use statistics and local engineering experience which have not been jointly and fully evaluated. Effective interpretation of the nature of channel change through time with respect to this resource may enhance the Environment Agency's ability to manage the river channel efficiently in the future and will aid the development of effective policy. The results of this study will for the first time, provide robust guidance with respect to long-term channel adjustment and the appropriate management options. The research provides suggestions as to how policy might be developed taking account of other pertinent factors.
Resumo:
Background: The impact of nano-scaled materials on photosynthetic organisms needs to be evaluated. Plants represent the largest interface between the environment and biosphere, so understanding how nanoparticles affect them is especially relevant for environmental assessments. Nanotoxicology studies in plants allude to quantum size effects and other properties specific of the nano-stage to explain increased toxicity respect to bulk compounds. However, gene expression profiles after exposure to nanoparticles and other sources of environmental stress have not been compared and the impact on plant defence has not been analysed. Results: Arabidopsis plants were exposed to TiO2-nanoparticles, Ag-nanoparticles, and multi-walled carbon nanotubes as well as different sources of biotic (microbial pathogens) or abiotic (saline, drought, or wounding) stresses. Changes in gene expression profiles and plant phenotypic responses were evaluated. Transcriptome analysis shows similarity of expression patterns for all plants exposed to nanoparticles and a low impact on gene expression compared to other stress inducers. Nanoparticle exposure repressed transcriptional responses to microbial pathogens, resulting in increased bacterial colonization during an experimental infection. Inhibition of root hair development and transcriptional patterns characteristic of phosphate starvation response were also observed. The exogenous addition of salicylic acid prevented some nano-specific transcriptional and phenotypic effects, including the reduction in root hair formation and the colonization of distal leaves by bacteria. Conclusions: This study integrates the effect of nanoparticles on gene expression with plant responses to major sources of environmental stress and paves the way to remediate the impact of these potentially damaging compounds through hormonal priming.
Resumo:
Kohl, U. (2005). Ignorance is no Defence but is Inaccessibility? On the Accessibility of National Laws to Foreign Online Publishers. Information & Communities Technology Law, 14 (1), 25-41. RAE2008 Information & Communications Technology Law Volume 14, Issue 1, 2005 Special Issue: GATED COMMUNITIES
Resumo:
Among the many issues that were raised in the White Book on National Security of the Republic of Poland (WBNSRP), there were also those related to the functioning of a Common Security and Defence Policy (CSDP). Its importance for the security of Poland was indicated, as well as the need on the part of EU Member States to broaden collaboration in the sphere of security and defence. The key problems occurring in the context of CSDP were also emphasised and their causes indicated. The aim of the article is to present the factors responsible for the weakening of CSDP effectiveness, ones taken into account in the White Book, and subsequently to present a Framework for their analysis in the light of further scholarship.