1,076 research outputs found

    The role and purpose of middle leaders in schools

    Get PDF

    Masticatory musculature of the African mole-rats (Rodentia: Bathyergidae)

    Get PDF
    The Bathyergidae, commonly known as blesmols or African mole-rats, is a family of rodents well-known for their subterranean lifestyle and tunnelling behaviour. Four of the five extant bathyergid genera (Cryptomys, Fukomys, Georychus and Heliophobius) are chisel-tooth diggers, that is they dig through soil with their enlarged incisors, whereas the remaining genus (Bathyergus) is a scratch-digger, only using its forelimbs for burrowing. Heterocephalus glaber, the naked mole-rat, is also a chisel-tooth digger and was until recently included within the Bathyergidae (as the most basally branching genus), but has now been placed by some researchers into its own family, the Heterocephalidae. Given the importance of the masticatory apparatus in habitat construction in this group, knowledge and understanding of the morphology and arrangement of the jaw-closing muscles in Bathyergidae is vital for future functional analyses. Here, we use diffusible iodine-based contrast-enhanced microCT to reveal and describe the muscles of mastication in representative specimens of each genus of bathyergid mole-rat and to compare them to the previously described musculature of the naked mole-rat. In all bathyergids, as in all rodents, the masseter muscle is the most dominant component of the masticatory musculature. However, the temporalis is also a relatively large muscle, a condition normally associated with sciuromorphous rodents. Unlike their hystricomorphous relatives, the bathyergids do not show an extension of the masseter through the infraorbital foramen on to the rostrum (other than a very slight protrusion in Cryptomys and Fukomys). Thus, morphologically, bathyergids are protrogomorphous, although this is thought to be secondarily derived rather than retained from ancestral rodents. Overall, the relative proportions of the jaw-closing muscles were found to be fairly consistent between genera except in Bathyergus, which was found to have an enlarged superficial masseter and relatively smaller pterygoid muscles. It is concluded that these differences may be a reflection of the behaviour of Bathyergus which, uniquely in the family, does not use its incisors for digging

    Net Yield Efficiency:Comparing Salad and Vegetable Waste between Community Supported Agriculture and Supermarkets in the UK

    Get PDF
    Food security is high on the global agenda. Two factors make it particularly pressing: the continuing rise in the global population, and the failure to adequately feed the current one. An area that has been the focus of much recent attention has been food waste; the Food and Agriculture Organization of the United Nations (FAO) estimates that as much as a third of all food is lost or wasted. This paper argues that by taking a food system approach that accounts for yields as well as loss and waste in distribution and consumption, we can compare the contribution of different food systems to food security. A novel concept of “net yield efficiency” (NYE) is introduced that accounts for this. We present an illustrative case study of the levels of fresh vegetable and salad waste in the supermarket-controlled food system compared with a commu­nity supported agriculture (CSA) scheme. This case study explores whether the CSA and its members are less wasteful than the supermarket system. The study found that when all stages of the food system were measured for waste, the CSA dramatically outperformed the supermarket system, wasting only 6.71% by weight compared to 40.7–47.7%. Even accounting for difficulties in estimating waste, the findings underline the differences between these systems. On this basis, the paper argues that the NYE measure provides a more accurate picture of food system performance than current measures, which tend to focus on yield alone

    Energetic Benefits of Sociality Offset the Costs of Parasitism in a Cooperative Mammal

    Get PDF
    We thank the owners for access to their property for animal capture and KwaZulu-Natal Nature Conservation Service for issuing the capture permit. This research was funded by the NRF-SAR Chair for Mammalian Behavioural Ecology and Physiology to NCB and University of Pretoria PDRF's to MS and HL. Many assistants were involved with fieldwork but we would especially like to thank Marietjie Oosthuizen and Craig Jackson for their help. This research was funded by the Department of Science and Technology/National Research Foundation-South African Research Chairs Initiative Chair for Mammalian Behavioural Ecology and Physiology to N.C.B. and University of Pretoria Postdoctoral Research Fellowships to M.S. and H.L. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

    Effects of cortisol administration on cooperative behavior in meerkat helpers

    Get PDF
    Experimental administration of stress hormones to meerkat helpers does not affect their contributions to cooperative activities. Previous work on cooperative breeders suggested that levels of stress hormones are related to helping behavior. We tested this experimentally by injecting meerkat helpers with cortisol, whilst matched controls received a saline injection. This did not lead to changes in cooperative behaviour, but induced females, and not males, to spend more time near pups and less time foragin

    Judging the impact of leadership-development activities on school practice

    Get PDF
    The nature and effectiveness of professional-development activities should be judged in a way that takes account of both the achievement of intended outcomes and the unintended consequences that may result. Our research project set out to create a robust approach that school staff members could use to assess the impact of professional-development programs on leadership and management practice without being constrained in this judgment by the stated aims of the program. In the process, we identified a number of factors and requirements relevant to a wider audience than that concerned with the development of leadership and management in England. Such an assessment has to rest upon a clear understanding of educational leadership,a clearly articulated model of practice, and a clear model of potential forms of impact. Such foundations, suitably adapted to the subject being addressed, are appropriate for assessing all teacher professional development
    corecore