541 research outputs found

    Efficiency of fall-banded nitrogen fertilizer in Manitoba: influence of application date, landscape position and fertilizer additives

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    Non-Peer ReviewedA two-year study was conducted to investigate the effects of application date, landscape position and a double inhibitor (urease and nitrification) on the efficiency of fall-banded nitrogen (N) fertilizer under Manitoba conditions. At harvest, the effects of landscape position were apparent at three of the four intensive sites, with significantly greater grain yields and total recovery of N in the high landscape positions than in the low landscape positions. Among fertilization treatments, there were no significant differences in crop response within the high landscape positions. In the low landscape positions, grain yields, total N uptake, grain yield increases and fertilizer N use efficiency were highest for the spring and late fall applications, when compared to early fall, mid fall and early fall with inhibitors. Preliminary soil analyses indicate that percent recovery of total inorganic N in the fall and spring was greater for late fall applications than for early fall, and for high as opposed to low landscape positions. However, there was little evidence of substantial disappearance of mineral N over the winter for all application dates, landscape positions, and with or without inhibitors

    The mental health of university students in the United Kingdom

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    There are increasing concerns globally about the mental health of students (Kadison,& Digeronimo, 2004). In the UK, the actual incidence of mental disturbance is unknown, although university counselling services report increased referrals (Association of University & College Counselling, 2011). This study assesses the levels of mental illness in undergraduate students to examine whether widening participation in education has resulted in increases as hypothesized by the UK Royal College of Psychiatrists (2003, 2011). Patterns of disturbance across years are compared to identify where problems arise. Students (N = 1197) completed the General Health Questionnaire-28 either on day one at university or midway through the academic year for first, second and third year students. Rates of mental illness in students equalled those of the general population but only 5.1% were currently receiving treatment. Second year students reported the most significant increases in psychiatric symptoms. Factors contributing to the problem are discussed

    Economics of preceding crops and nitrogen application rates for canola and barley production in western Canada

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    Non-Peer ReviewedThe objective of this study was to evaluate the economic effects of a range of legume and non-legume preceding crops and N rates on costs and net revenue (NR) of canola (Brassica napus L.), barley (Hordeum vulgare L.) and canola-barley rotation under various environmental conditions. Legumes such as field pea (Pisum sativum L.) and lentil (Lens culinaris Medik.) as preceding crop generated higher net revenues for the following crops canola and barley than when wheat (Triticum aestivum L.) and canola were the preceding crops. Although faba bean (Vicia faba L.) grown as a green manure produced the highest annual net revenues for the following crops canola and barley, this contribution was not enough to compensate for the loss of income during the green manure production year. Therefore, growing faba bean as a green manure was not economical. Response of net revenue to N rates was mainly linear or quadratic, and N was optimal at 60 to 90 kg ha-1 at most sites. The results indicate that growing legumes for seed prior to canola can increase net revenues of canola and subsequent barley

    New directions in island biogeography

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    Aim: Much of our current understanding of ecological and evolutionary processes comes from island research. With the increasing availability of data on distributions and phylogenetic relationships and new analytical approaches to understanding the processes that shape species distributions and interactions, a re-evaluation of this ever-interesting topic is timely. Location: Islands globally. Methods: We start by arguing that the reasons why island research has achieved so much in the past also apply to the future. We then critically assess the current state of island biogeography, focusing on recent changes in emphasis, including research featured in this special issue of Global Ecology and Biogeography. Finally, we suggest promising themes for the future. We cover both ecological and evolutionary topics, although the greater emphasis on island ecology reflects our own backgrounds and interests. Results: Much ecological theory has been directly or indirectly influenced by research on island biotas. Currently, island biogeography is renascent, with research focusing on, among other things, patterns and processes underlying species interaction networks, species coexistence and the assembly of island communities through ecological and evolutionary time. Continuing island research should provide additional insight into biological invasions and other impacts of human activities, functional diversity and ecosystem functioning, extinction and diversification, species pools and more. Deeper understanding of the similarities and differences between island and mainland systems will aid transferability of island theory to continental regions. Main conclusions: As research in biogeography and related fields expands in new directions, islands continue to provide opportunities for developing insights, both as natural laboratories for ecology and evolution and because of the exceptions islands often present to the usual ‘rules’ of ecology. New data collection initiatives are needed on islands world-wide and should be directed towards filling gaps in our knowledge of within-island distributions of species, as well as the functional traits and phylogenetic relationships of island species

    Electromagnetic Interactions GEneRalized (EIGER) - Algorithm abstraction and HPC implementation

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    Modern software development methods combined with key generalizations of standard computational algorithms enable the development of a new class of electromagnetic modeling tools. This paper describes current and anticipated capabilities of a frequency domain modeling code, EIGER, which has an extremely wide range of applicability. In addition, software implementation methods and high performance computing issues are discussed

    Stellar structure and compact objects before 1940: Towards relativistic astrophysics

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    Since the mid-1920s, different strands of research used stars as "physics laboratories" for investigating the nature of matter under extreme densities and pressures, impossible to realize on Earth. To trace this process this paper is following the evolution of the concept of a dense core in stars, which was important both for an understanding of stellar evolution and as a testing ground for the fast-evolving field of nuclear physics. In spite of the divide between physicists and astrophysicists, some key actors working in the cross-fertilized soil of overlapping but different scientific cultures formulated models and tentative theories that gradually evolved into more realistic and structured astrophysical objects. These investigations culminated in the first contact with general relativity in 1939, when J. Robert Oppenheimer and his students George Volkoff and Hartland Snyder systematically applied the theory to the dense core of a collapsing neutron star. This pioneering application of Einstein's theory to an astrophysical compact object can be regarded as a milestone in the path eventually leading to the emergence of relativistic astrophysics in the early 1960s.Comment: 83 pages, 4 figures, submitted to the European Physical Journal

    Automated Analysis in Feature Modelling and Product Configuration

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    The automated analysis of feature models is one of the thriving topics of research in the software product line and variability management communities that has attracted more attention in the last years. A recent literature review reported that more than 30 analysis operations have been identi ed and di erent analysis mechanisms have been proposed. Product con guration is a well established research eld with more than 30 years of successful applications in di erent industrial domains. Our hypothesis, that is not really new, is that these two independent areas of research have interesting synergies that have not been fully explored. To try to explore the potential synergies systematically, in this paper we provide a rapid review to bring together these previously disparate streams of work. We de ne a set of research questions and give a preliminary answer to some of them. We conclude that there are many research opportunities in the synergy of these independent areas.Ministerio de Ciencia e Innovación TIN2009- 07366Junta de Andalucía TIC-590
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