62,741 research outputs found

    Matrilines in Neolithic cattle from Orkney, Scotland reveals complex husbandry patterns of ancestry

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    mtDNA, isotopic and archaeozoological analyses of cattle teeth and bones from the Late Neolithic site of Links of Noltland, Orkney, Scotland revealed these animals followed similar grazing regimes but displayed diverse genetic origins and included one cattle skull that carried an aurochs (wild cattle) genetic haplotype. Morphometric analyses indicate the presence of some cattle larger than published dimensions of Neolithic domestic cattle. Several explanations for these finding are possible but may be the evidence of a complex pattern of domestic cattle introductions into Neolithic Orkney and interbreeding between domestic and wild cattle

    University of Aarhus - the stepping stones

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    The University of Aarhus has more than 20,000 students, making it the second-largest university in Denmark. It is also the second-oldest university in the country, and is celebrating its 75th anniversary in 2003. Like the other Danish universities, the University of Aarhus is currently facing major challenges. Changes in the Danish University Act and a strong political wish for closer partnerships between the private business community, the public sector and the country?s universities have gradually altered the role of the universities in Denmark today. This paper looks more closely at the history of the University of Aarhus, the importance of the University for the Aarhus region, and the opportunities and barriers facing an ?old? comprehensive University in its attempts to adapt to the new role of universities in the modern world.

    Living Without a Mobile Phone: An Autoethnography

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    This paper presents an autoethnography of my experiences living without a mobile phone. What started as an experiment motivated by a personal need to reduce stress, has resulted in two voluntary mobile phone breaks spread over nine years (i.e., 2002-2008 and 2014-2017). Conducting this autoethnography is the means to assess if the lack of having a phone has had any real impact in my life. Based on formative and summative analyses, four meaningful units or themes were identified (i.e., social relationships, everyday work, research career, and location and security), and judged using seven criteria for successful ethnography from existing literature. Furthermore, I discuss factors that allow me to make the choice of not having a mobile phone, as well as the relevance that the lessons gained from not having a mobile phone have on the lives of people who are involuntarily disconnected from communication infrastructures.Comment: 12 page

    GIER: A Danish computer from 1961 with a role in the modern revolution of astronomy

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    A Danish computer, GIER, from 1961 played a vital role in the development of a new method for astrometric measurement. This method, photon counting astrometry, ultimately led to two satellites with a significant role in the modern revolution of astronomy. A GIER was installed at the Hamburg Observatory in 1964 where it was used to implement the entirely new method for the measurement of stellar positions by means of a meridian circle, then the fundamental instrument of astrometry. An expedition to Perth in Western Australia with the instrument and the computer was a success. This method was also implemented in space in the first ever astrometric satellite Hipparcos launched by ESA in 1989. The Hipparcos results published in 1997 revolutionized astrometry with an impact in all branches of astronomy from the solar system and stellar structure to cosmic distances and the dynamics of the Milky Way. In turn, the results paved the way for a successor, the one million times more powerful Gaia astrometry satellite launched by ESA in 2013. Preparations for a Gaia successor in twenty years are making progress.Comment: 19 pages,8 figures, Accepted for publication in Nuncius Hamburgensis, Volume 2

    Probing the Protosolar Disk Using Dust Filtering at Gaps in the Early Solar System

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    Jupiter and Saturn formed early, before the gas disk dispersed. The presence of gap-opening planets affects the dynamics of the gas and embedded solids and halts the inward drift of grains above a certain size. A drift barrier can explain the absence of calcium aluminium rich inclusions (CAIs) in chondrites originating from parent bodies that accreted in the inner solar system. Employing an interdisciplinary approach, we use a μ\mu-X-Ray-fluorescence scanner to search for large CAIs and a scanning electron microscope to search for small CAIs in the ordinary chondrite NWA 5697. We carry out long-term, two-dimensional simulations including gas, dust, and planets to characterize the transport of grains within the viscous α\alpha-disk framework exploring the scenarios of a stand-alone Jupiter, Jupiter and Saturn \textit{in situ}, or Jupiter and Saturn in a 3:2 resonance. In each case, we find a critical grain size above which drift is halted as a function of the physical conditions in the disk. From the laboratory search we find four CAIs with a largest size of \approx200μ\,\mum. \Combining models and data, we provide an estimate for the upper limit of the α\alpha-viscosity and the surface density at the location of Jupiter, using reasonable assumptions about the stellar accretion rate during inward transport of CAIs, and assuming angular momentum transport to happen exclusively through viscous effects. Moreover, we find that the compound gap structure in the presence of Saturn in a 3:2 resonance favors inward transport of grains larger than CAIs currently detected in ordinary chondrites.Comment: 16 pages, 10 figures, updated to match published version in Astrophysical Journa

    Environmental conditions during early life accelerate the rate of senescence in a short-lived passerine bird

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    Environmental conditions experienced in early life may shape subsequent phenotypic traits including life history. We investigated how predation risk caused by domestic cats (Felis silvestris catus) and local breeding density affected patterns of reproductive and survival senescence in Barn Swallows (Hirundo rustica) breeding semicolonially in Denmark. We recorded the abundance of cats and the number of breeding pairs at 39 breeding sites during 24 years and related these to age-specific survival rate and reproductive senescence to test predictions of the life history theory of senescence. We found evidence for actuarial senescence for the first time in this species. Survival rate increased until reaching a plateau in midlife and then decreased later. We also found that survival rate was higher for males than females. Local breeding density or predation risk did not affect survival as predicted by theory. Barn Swallows with short lives did not invest more in reproduction in early life, inconsistent with expectations for trade-offs between reproduction and survival as theory suggests. However, we found that the rate of reproductive decline during senescence was steeper for individuals exposed to intense competition, and predation pressure accelerated the rate of reproductive senescence, but only in sites with many breeding pairs. These latter results are in accordance with one of the predictions suggested by the life history theory of aging. These results emphasize the importance of considering intraspecific competition and interspecific interactions such as predation when analyzing reproductive and actuarial senescence

    Participatory design and participatory development: a comparative review

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    This paper examines literature in the twin domains of participatory interactive systems design and participatory approaches to international development. As interactive systems are increasingly promoted as a possible means of achieving international development goals, designers generally agree that participatory design approaches should be applied. However, review of the literature reveals that these two different traditions have more complex relationships, and questions must be asked about: the aims of participation, the forms of participation that are being advocated, and the skills and strategies required of practitioners. The findings suggest that successful integration of participatory interactive systems design into development will require careful reflection on the nature of development and the approaches adopted.</p

    Taxonomy, systematics and ecology of the phylum Tardigrada

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    This thesis is based on published papers, however there have been issues encountered with copyright permissions, therefore a fuller version may be submitted in the future.I conducted a series of research programmes on various aspects of Tardigrada biology. The published results of which are hereby presented as part fulfilment of my submission for a PhD by publications at Plymouth University. In this thesis my research publications are grouped into four chapters: Ecology & Faunistics, Alpha Taxonomy, Freshwater Fauna – a taxonomic challenge, and Superfamilies. In the first, I highlight my early papers which dealt with the faunistic surveys as I trained in systematics and taxonomy of the phylum. Amongst the key findings reported were the protozoan symphoriant, Pyxidium tardigradum van der Land, 1966, Marley and Wright (1994); a new addition to the reported fauna of the United Kingdom, Greaves & Marley(1996); and my first work on international samples from Arctic Canada, Sutcliffe et al.(2000). In the second chapter, Alpha Taxonomy, I have included five papers. The first, Marley and Wright (1996), illustrates my work with one of the Royal Museums of Scotland’s collections, where I updated the diagnoses of their specimens and described a new addition to the Icelandic fauna. The second paper, Russell, Marley & Hockings (2001), demonstrates how I was searching for new research methods to apply to tardigrades. It was because of similar exploration, with methods of SEM preparation, that I was invited to join the Australian-Anglo team working on sediment core samples from Antarctic freshwater lakes, Gibson et al. 2009. The remaining two papers in the chapter describe species new to science, Echiniscus ollantaytamboensis Nickel, Miller and Marley, 2001, and my first sole authored paper describing a species new to science, Platicrista ramsayi Marley, 2006. The third chapter, Freshwater Fauna – a taxonomic challenge, deals with a programme of research based initially on my findings at the Royal Museums of Scotland, Edinburgh. This then required subsequent visits the USA and Italy to work on the taxonomic issues with original authors on their more recently described genera. I prepared the original Case for the ICZN, but this was then held by the commission for several years pending their amendments to the Code. I then rewrote the Case into the final paper, Marley, Bertolani & Nelson (2008). The final chapter consists of two papers in which I worked on combining my expertise on the morphological characters of the buccal apparatus and claws, and combining this with new molecular dataset derived from sequencing individual specimens. My colleagues on these papers were Dr S.J. McInnes and Mr C.J. Sands, both from the British Antarctic Survey. Overall I am including 14 published papers and 5 published conference abstracts and three online articles. The following taxa were erected during this work: Pseudobiotus kathmanae, Echiniscus ollantaytamboensis, Platicrista ramsayi, Ramazzottidae, Isohypsibiidae, Macrobiotoidea, Eohypsibioidea, Hypsibioidea, and Isohypsibioidea. Plus the following taxa were re-described, Pseudobiotus, Thulinius, Thulinius augusti, Thulinius ruffoi, and Thulinius stephanae

    Assessing computer skills in Tanzanian medical students: an elective experience

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    Background: One estimate suggests that by 2010 more than 30% of a physician's time will be spent using information technology tools. The aim of this study is to assess the information and communication technologies (ICT) skills of medical students in Tanzania. We also report a pilot intervention of peer mentoring training in ICT by medical students from the UK tutoring students in Tanzania. Methods: Design: Cross sectional study and pilot intervention study. Participants: Fourth year medical students (n = 92) attending Muhimbili University College of Health Sciences, Dar es Salaam, Tanzania. Main outcome measures: Self-reported assessment of competence on ICT-related topics and ability to perform specific ICT tasks. Further information related to frequency of computer use (hours per week), years of computer use, reasons for use and access to computers. Skills at specific tasks were reassessed for 12 students following 4 to 6 hours of peer mentoring training. Results: The highest levels of competence in generic ICT areas were for email, Internet and file management. For other skills such as word processing most respondents reported low levels of competence. The abilities to perform specific ICT skills were low – less than 60% of the participants were able to perform the core specific skills assessed. A period of approximately 5 hours of peer mentoring training produced an approximate doubling of competence scores for these skills. Conclusion: Our study has found a low level of ability to use ICT facilities among medical students in a leading university in sub-Saharan Africa. A pilot scheme utilising UK elective students to tutor basic skills showed potential. Attention is required to develop interventions that can improve ICT skills, as well as computer access, in order to bridge the digital divide
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