395 research outputs found

    Impact of Flower Harvesting on the Salt Marsh Plant \u3cem\u3eLimonium carolinianum\u3c/em\u3e

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    Because of the potentially detrimental effects of seed production on adult survivorship and growth, moderate flower harvesting may have little negative impact on population growth of long-lived perennial plants such as Limonium carolinianum (Walter) Britton. We examined this by collecting data on survivorship, growth, and fecundity of an unharvested population over a period of 5 years and conducted a controlled experiment to examine the effect of harvesting on adult survivorship and growth over a 3-year period. Data were summarized in the form of a stage structured matrix population model with a stochastic element that incorporated year-to-year variation in transition probabilities. Contrary to our original hypothesis, we found that preventing seed set through removal of flowers did not increase adult survivorship or growth. By determining the harvest level that reduced population growth rate to 1.0, we estimated the maximum sustainable harvest level to be 16%, a value that is approximately half that of reported harvest levels on accessible marshes in the study area. In spite of this, the reported harvest levels are unlikely to drive local populations to extinction in the foreseeable future. Providing the adult population size is \u3e100 and harvest levels are \u3c90%, time to local extinction will exceed 100 years. This is a function of the very high survivorship of adults in this species and the fact that harvesting has no negative impact on adult survivorship or growth. However, because of the long preadult phase in this species (8ā€“9 years) and the fact that fecundity of young adults is low, recovery from overharvesting is extremely slow. Adult population size can be reduced to 25% of its original value in 7 years at high harvest levels, but it will take 34 years on average to recover once harvesting is terminated

    Single-frequency ytterbium-doped fibre laser stabilised by spatial hole burning

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    We have exploited spatial hole burning to achieve remarkably stable single-frequency operation and mode-hop-free tuning over 300 free spectral ranges in an ytterbium-doped fiber laser with a sample standing-wave geometry. This approach makes possible stable and narrow-linewidth single-frequency fiber lasers that do not require components such as Faraday isolators, fiber couplers, and Fabry-Perot filters

    Risk of cancer following primary total hip replacement or primary resurfacing arthroplasty of the hip : A retrospective cohort study in Scotland

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    Acknowledgements: We are grateful to Lee Barnsdale, Doug Clark, and Richard Dobbie for advice and assistance with data preparation before analysis, and to the three anonymous referees for their helpful comments and suggestions.Peer reviewedPublisher PD

    Trends in chlamydia and gonorrhoea testing and positivity in Western Australian Aboriginal and non-Aboriginal women 2001-2013: a population based cohort study

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    Aims: To examine trends in chlamydia and gonorrhoea testing and positivity in Aboriginal and non-Aboriginal women of reproductive age. Methods: A cohort of 318002 women, born between 1974-1995, residing in Western Australia (WA) was determined from birth registrations and the 2014 electoral roll. This cohort was then probabilistically linked to all records of chlamydia and gonorrhoea nucleic acid amplification tests (NAAT) conducted between 1st January 2001 and 31st December 2013 by two large WA pathology laboratories. Trends in chlamydia and gonorrhoea testing and positivity were investigated over time and stratified by Aboriginality and age group. Results: The proportion of women tested annually for chlamydia increased significantly between 2001 and 2013 from 24% to 37% in Aboriginal and 4.0% to 8.5% in non-Aboriginal women (both p-values80%) and so patterns of gonorrhoea testing were similar. Chlamydia and gonorrhoea positivity were substantially higher in Aboriginal compared to non-Aboriginal women; age-, region- and year-adjusted Incidence Rate Ratioā€™s 1.52(95%CI 1.50-1.69, p Conclusion: Between 2001 and 2013 in WA chlamydia and gonorrhoea positivity remained highest in young Aboriginal women despite chlamydia positivity increasing among young non-Aboriginal women. More effective prevention strategies, particularly in young Aboriginal women are needed to addres these disparitie

    Factors associated with zidovudine substitution in HIV/AIDS patients attending Badung Hospital, Bali, Indonesia between 2006-2014

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    Background: Zidovudine (AZT) is the most commonly used drug in first line antiretroviral therapy (ART) in Indonesia; however, substitution due to its side effect is common. The majority of HIV positive patients in Badung Hospital Bali are treated with AZT yet no longitudinal studies in Bali have investigated the number of substitutions or the factors associated with it.Methods: A retrospective cohort study of HIV positive persons aged >15 years, receiving AZT between 1st January 2006 ā€“ 31st August 2014 was conducted. Persons were included from their date of starting AZT. Cox proportional hazard models were applied to estimate the risk and time to substitution. Substitution was defined as single drug change due to side effects and initiating another drug of the same class.Results: During our study 260 patients started AZT, of which 77 (29.6%) experienced substitution. The risk of substitution was 19 per 100 person years. Of those 77, the median time to AZT substitution was 69 days (IQR 25-178). Factors significantly associated with an increased risk of AZT substitution included women (HR 1.79; 95% CI 1.09-2.94), having low hemoglobin levels <10g% (HR 2.72; 95% CI 1.02-7.21), clinical stage III and IV (HR 3.53; 95% CI 1.26-6.19) at the time of starting AZT, and starting ART after 2012 (HR 3.83; 95% CI 2.19-6.70).Conclusions: Present study identified individuals that may be at a high risk of AZT substitution who should be monitored more closely or consideration given to initiating them on another treatment regimen

    The role of polycyclic frameworks in modulating P2X<inf>7</inf> receptor function

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    Herein we describe our recent attempts to target the P2X7 receptor for potential treatment of neurological disorders. This work focusses on different polycycles including carborane, adamantane or cubane, joined by either a cyanoguanidine or an amide linker to phenyl or isoquinoline moieties. We have demonstrated the superiority of the adamantyl moiety over other polycycles in terms of synthetic accessibility and biological (cellular) activity. We have also shown that an amide or cyanoguanidine linker can greatly alter the biological activity of compounds. This SAR study provides important insights into the types of functionality required to target the P2X7 receptor

    An overview of late-stage functionalization in today's drug discovery

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    Introduction: Late-stage functionalization (LSF) can introduce important chemical groups in the very last steps of the synthesis. LSF has the potential to speed up the preparation of novel chemical entities and diverse chemical libraries and have a major impact on drug discovery. Functional group tolerance and mild conditions allows access to new molecules not easily accessible by conventional approaches without the need for laborious de novo chemical synthesis. Areas Covered: A historical overview of late-stage functionalization and its applicability to drug discovery is provided. Pioneering methodologies that laid the foundations for the field are briefly covered and archetypal examples of their application to drug discovery are discussed. Novel methodologies reported in the past few years mainly stemming from the recent renaissances of photoredox catalysis and radical chemistry are reviewed and their application to drug discovery considered. Expert opinion: It is envisioned that late-stage functionalization will improve the efficiency and efficacy of drug discovery. There is evidence of the widespread uptake of LSF by the medicinal chemistry community and it is expected that the recent and continuing endeavors of many academic laboratories and pharmaceutical companies will soon have an impact on drug development.The authors are supported by the National Health and Medical Research Council of Australi

    HIV testing in re-education through labour camps in Guangxi Autonomous Region, China (a cross-sectional survey)

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    Objective: HIV testing is mandatory in re-education-through-labour camps (laojiaosuo) in China yet no studies have reported on the process. Methods: The survey response rate was 100% although 29 detainees were excluded because they were under 18 years of age. A cross-sectional face-to-face survey was conducted in three labour camps in Guangxi, located in the south-western region of China. Results: Of the 755 detainees surveyed, 725 (96%) reported having a blood test in the labour camps of whom 493 (68%) thought this included an HIV test. 61 detainees self-reported they were HIV infected, their status confirmed by medical records, if available. Of these, 53 (87%) recalled receiving post-test HIV education, and 15 (25%) were currently receiving HIV antiretroviral therapy. Pretest education on HIV was provided to 233/725 (32%) detainees. The study further reports on detaineesā€™ reactions and feelings towards non-disclosure and disclosure of their HIV test results in the labour camps. Conclusions: Mandatory testing is almost universal in the labour camps although a proportion of detainees were unaware that this included an HIV test. HIV test results should be disclosed to all labour camp detainees to reduce their distress of not knowing and prevent misconceptions about their HIV status. Labour camps provide another opportunity to implement universal treatment (ā€˜Test and Treatā€™) to prevent the spread of HIV
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