27,937 research outputs found

    Parameter estimates for fractional autoregressive spatial processes

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    A binomial-type operator on a stationary Gaussian process is introduced in order to model long memory in the spatial context. Consistent estimators of model parameters are demonstrated. In particular, it is shown that d^Nd=OP((LogN)3N)\hat{d}_N-d=O_P(\frac{(\operatorname {Log}N)^3}{N}), where d=(d1,d2)d=(d_1,d_2) denotes the long memory parameter.Comment: Published at http://dx.doi.org/10.1214/009053605000000589 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Comparison of different objective functions for parameterization of simple respiration models

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    The eddy covariance measurements of carbon dioxide fluxes collected around the world offer a rich source for detailed data analysis. Simple, aggregated models are attractive tools for gap filling, budget calculation, and upscaling in space and time. Key in the application of these models is their parameterization and a robust estimate of the uncertainty and reliability of their predictions. In this study we compared the use of ordinary least squares (OLS) and weighted absolute deviations (WAD, which is the objective function yielding maximum likelihood parameter estimates with a double exponential error distribution) as objective functions within the annual parameterization of two respiration models: the Q10 model and the Lloyd and Taylor model. We introduce a new parameterization method based on two nonparametric tests in which model deviation (Wilcoxon test) and residual trend analyses (Spearman test) are combined. A data set of 9 years of flux measurements was used for this study. The analysis showed that the choice of the objective function is crucial, resulting in differences in the estimated annual respiration budget of up to 40%. The objective function should be tested thoroughly to determine whether it is appropriate for the application for which the model will be used. If simple models are used to estimate a respiration budget, a trend test is essential to achieve unbiased estimates over the year. The analyses also showed that the parameters of the Lloyd and Taylor model are highly correlated and difficult to determine precisely, thereby limiting the physiological interpretability of the parameter

    Do student nurses feel a lack of comfort in providing support for Lesbian, Gay, Bisexual or Questioning adolescents: what factors influence their comfort level?

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    Aim: The aim of this study was to find out if student nurses feel comfortable in caring by providing support for Lesbian, Gay, Bisexual or Questioning adolescents and what factors influence their level of comfort. Background: Research indicates that nurses and nursing students experience varying levels of comfort when caring for adults who are Lesbian, Gay, Bisexual or Questioning: adult patients feel that nurse’s attitudes change towards them once they disclose their sexuality. There has been minimal research to date on nursing attitudes to working with adolescents who are Lesbian, Gay, Bisexual or Questioning. Design Both quantitative and qualitative methods were used in this descriptive study. Questionnaires were completed by 152 nursing students and 9 took part in semi-structured focus groups. Method: A two way ANOVA was used to analyse the questionnaires. Thematic analysis was used to identify the themes arising from the focus groups. Data was collected between August 2013 and July 2014. Results/Findings: The results and findings of the study were that student nurse’s felt discomfort in providing support; due to a lack of knowledge of Lesbian, Gay or Bisexual sexuality, personal and religious beliefs and the perceptions of others. However, all students indicated they had a positive attitude towards Lesbian, Gay, Bisexual and Questioning adolescents. Conclusion: More needs to be done to raise self-awareness and improve the level of knowledge in relation to Lesbian, Gay and Bisexual issues amongst student nurses. Educational institutions and practice areas need to recognize this fact and reflect this in their educational programmes

    Evolutionary cell biology: Functional insight from “Endless forms most beautiful”

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    In animal and fungal model organisms, the complexities of cell biology have been analyzed in exquisite detail and much is known about how these organisms function at the cellular level. However, the model organisms cell biologists generally use include only a tiny fraction of the true diversity of eukaryotic cellular forms. The divergent cellular processes observed in these more distant lineages are still largely unknown in the general scientific community. Despite the relative obscurity of these organisms, comparative studies of them across eukaryotic diversity have had profound implications for our understanding of fundamental cell biology in all species and have revealed the evolution and origins of previously observed cellular processes. In this Perspective, we will discuss the complexity of cell biology found across the eukaryotic tree, and three specific examples of where studies of divergent cell biology have altered our understanding of key functional aspects of mitochondria, plastids, and membrane trafficking

    Radiation and mortality of workers at Oak Ridge National Laboratory: positive associations for doses received at older ages.

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    We examined associations between low-level exposure to ionizing radiation and mortality among 14,095 workers hired at the Oak Ridge National Laboratory between 1943 and 1972. Workers at the facility were individually monitored for external exposure to ionizing radiation and have been followed through 1990 to ascertain cause of death information. Positive associations were observed between low-level exposure to external ionizing radiation and mortality. These associations were larger for doses received after 45 years of age, larger under longer lag assumptions, and primarily due to cancer causes of death. All cancer mortality was estimated to increase 4.98% [standard error (SE) = 1.5] per 10-mSv cumulative dose received after age 45 under a 10-year lag, and 7.31% (SE = 2.2) per 10-mSv cumulative dose received after age 45 under a 20-year lag. Associations between radiation dose and lung cancer were of similar magnitude to associations between radiation dose and all cancers except lung cancer. Nonmalignant respiratory disease exhibited a positive association with cumulative radiation dose received after age 45, whereas ischemic heart disease exhibited no association with radiation dose. These findings suggest increases in cancer mortality associated with low-level external exposure to ionizing radiation and potentially greater sensitivity to the carcinogenic effects of ionizing radiation with older ages at exposure

    Contribution of Non-Timber Forest Products to Rural Household Income in Zambia

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    Non-timber forest products (NTFPs) play an important role in supporting rural livelihoods and food security in Zambia. NTFP-dependent households are poorer, have younger household heads with lower levels of education, and are located closer to district towns than other rural households are. NTFPs are a particularly important source of income in Luapula, Northwestern and Western provinces. • Income from woodfuel represented the greatest share of income for households that participated in NTFPs, and it was the most commonly reported business activity, with 68% of NTFP households reporting income from charcoal and firewood. NTFPs contribute an average of 32% to total household income among participants, with the poorest being more dependent on these sources. • Given the widespread demand for woodfuel and other forest products, it is likely that rural households will continue to engage in the extraction and trade of NTFPs as a business activity. However, charcoal production, if left unchecked, could compromise the integrity of forests and adversely affect the availability of other NTFPs. In order to reduce households’ reliance on charcoal/firewood as an income source, outreach efforts could promote other NTFPs such as wild honey, ants, and mushrooms as business activities. Mushrooms, ants, and caterpillars may particularly be important activities for female-headed households, as more female-headed households derived income from these sources.NON-TIMBER FOREST, ZAMBIA, Agricultural and Food Policy, Consumer/Household Economics,

    Weekend hospitalization and additional risk of death: An analysis of inpatient data

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    Objective To assess whether weekend admissions to hospital and/or already being an inpatient on weekend days were associated with any additional mortality risk.Design Retrospective observational survivorship study. We analysed all admissions to the English National Health Service (NHS) during the financial year 2009/10, following up all patients for 30 days after admission and accounting for risk of death associated with diagnosis, co-morbidities, admission history, age, sex, ethnicity, deprivation, seasonality, day of admission and hospital trust, including day of death as a time dependent covariate. The principal analysis was based on time to in-hospital death.Participants National Health Service Hospitals in England.Main Outcome Measures 30 day mortality (in or out of hospital).Results There were 14,217,640 admissions included in the principal analysis, with 187,337 in-hospital deaths reported within 30 days of admission. Admission on weekend days was associated with a considerable increase in risk of subsequent death compared with admission on weekdays, hazard ratio for Sunday versus Wednesday 1.16 (95% CI 1.14 to 1.18; P < .0001), and for Saturday versus Wednesday 1.11 (95% CI 1.09 to 1.13; P < .0001). Hospital stays on weekend days were associated with a lower risk of death than midweek days, hazard ratio for being in hospital on Sunday versus Wednesday 0.92 (95% CI 0.91 to 0.94; P < .0001), and for Saturday versus Wednesday 0.95 (95% CI 0.93 to 0.96; P < .0001). Similar findings were observed on a smaller US data set.Conclusions Admission at the weekend is associated with increased risk of subsequent death within 30 days of admission. The likelihood of death actually occurring is less on a weekend day than on a mid-week day

    A predictive phenomenological tool at small Bjorken-x

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    We present the results from global fits of inclusive DIS experimental data using the Balitsky-Kovchegov equation with running coupling.Comment: 5 pages, 2 figures, prepared for the Proceedings of 'Hot Quarks 2010
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