1,304 research outputs found
Seasonal changes in moult, body mass and reproductive condition in siskins Carduelis spinus exposed to daylength regimes simulating different latitudes
Birds use change in daylength during the year to time events during their annual cycles. Individual Eurasian siskins Carduelis spinus can breed and winter in widely separated areas in different years. Birds at different latitudes will experience different changes in photoperiod. So how does latitude affect photoperiodic control? Our aim in this study was to find whether siskins caught from the wild in Britain and exposed to different photoperiodic regimes, typical of widely separated latitudes, would differ in the subsequent timing and duration of their moults and associated processes. Siskins were caught in late February and early March, and initially kept outside on natural photoperiods. From the spring equinox (21 March), they were divided into three groups kept under photoperiodic regimes that simulated latitudes 40º, 55º and 70º N respectively. All three groups showed highly significant subsequent changes in body mass, fat scores and cloacal protuberance size. Moult of the primary feathers started during June – August (mean 9 July), and lasted 61-99 days (mean 75 days). Birds that started to moult late in the season had shorter moult durations. All individuals showed lower mass and fat levels during moult than before or after moult. Crucially, there were no significant differences in the timing of these events between the three photoperiodic groups. Apparently these birds did not use prevailing absolute photoperiod or the prevailing rate of change in photoperiod to time moult-related seasonal events, but used instead some other feature of the annual photoperiod cycle or some form of interval timer linked to photoperiod
Seeing the trees as well as the forest: the importance of managing forest genetic resources
Reliable data on the status and trends of forest genetic resources are essential for their sustainable management. The reviews presented in this special edition of Forest Ecology and Management on forest genetic resources complement the first ever synthesis of the State of the World’s Forest Genetic Resources (SOW-FGR) that has just been published by the Food and Agriculture Organization. In this editorial, we present some of the key findings of the SOW-FGR and introduce the seven reviews presented in this special edition on: (1) tree genetic resources and livelihoods; (2) the benefits and dangers of international germplasm transfers; (3) genetic indicators for monitoring threats to populations and the effectiveness of ameliorative actions; (4) the genetic impacts of timber management practices; (5) genetic considerations in forest ecosystem restoration projects using native trees; (6) genetic-level responses to climate change; and (7) ex situ conservation approaches and their integration with in situ methods. Recommendations for action arising from the SOW-FGR, which are captured in the first Global Plan of Action for the Conservation, Sustainable Use and Development of Forest Genetic Resources, and the above articles are discussed. These include: increasing the awareness of the importance of and threats to forest genetic resources and the mainstreaming of genetic considerations into forest management and restoration; establishing common garden provenance trials to support restoration and climate change initiatives that extend to currently little-researched tree species; streamlining processes for germplasm exchange internationally for research and development; and the intelligent use of modern molecular marker methods as genetic indicators in management and for improvement purposes
Threshold Resummed and Approximate NNLO results for W+W- Pair Production at the LHC
The next-to-leading order (NLO) QCD radiative corrections to W+W- production
at hadron colliders are well understood. We combine NLO perturbative QCD
calculations with soft-gluon resummation of threshold logarithms to find a
next-to-next-to leading logarithmic (NNLL) prediction for the total cross
section and the invariant mass distribution at the LHC. We also obtain
approximate next-to-next-to-leading order (NNLO) results for the total W+W-
cross section at the LHC which includes all contributions from the scale
dependent leading singular terms. Our result for the approximate NNLO total
cross section is the most precise theoretical prediction available.
Uncertainties due to scale variation are shown to be small when the threshold
logarithms are included. NNLL threshold resummation increases the W+W-
invariant mass distribution by ~ 3-4% in the peak region for both \sqrt{S}=8
and 14 TeV. The NNLL threshold resummed and approximate NNLO cross sections
increase the NLO cross section by 0.5-3% for \sqrt{S}=7, 8, 13, and 14 TeV.Comment: 29 pages, 7 figures, 3 tables. Discussion added to introduction,
references updated, and typos correcte
Evaluation of the reliability of an ergonomic decision system.
A novel approach deemed the Ergonomic Decision System (EDS) was designed to address the physical requirements of modern industry. The EDS, as the name implies, is a system that uses a series of questions and resulting choices to determine the path to the most appropriate ergonomic analysis tool for a given occupational task. The face validity of the EDS has been established through an extensive review of literature. Reliability was evaluated both within and between subjects. In two facilities, 6 Jobs were chosen based upon both injury and illness data and the differing physical requirements of each. These Jobs were video recorded and two Jobs were randomly chosen. Novice subjects (N = 6) were asked to apply the EDS to one of these jobs prior to being provided the basic ergonomic training. Subsequently, all trained subjects (N = 12) applied the EDS to the same 6 recorded Jobs. The results from the EDS applications were then compared to a criterion measure resulting in a total EDS score which was used to determine subject accuracy. A high overall mean accuracy value of 88.4%, was found with experts and novices varying only slightly with mean scores of 92.6% and 84.3%, respectively. Further, a consensus count was taken from each user for each condition to determine consistency. A good overall mean consensus, between subjects, of 76.9% was found with experts scoring 85% and novice subjects 72%. Also, the results of the pre-post training study indicated strong within subject consensus with an average of 88.9% across novice subjects. Finally, after a minimum of two weeks had passed, all subjects applied the EDS to the second randomly chosen Job. Results of the test-retest condition showed good consensus within subjects with a mean of 94.4%, where experts scored 88.9%, and novice subjects showed perfect consensus. The results of the study effectively establish that the EDS provided sufficient subject consistency and accuracy in directing subjects to the most applicable ergonomic resource across Jobs tested.Dept. of Industrial and Manufacturing Systems Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2006 .D39. Source: Masters Abstracts International, Volume: 45-01, page: 0435. Thesis (M.A.Sc.)--University of Windsor (Canada), 2006
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