1,173 research outputs found
Evaluación de los modelos ultraestructurales y de efectos aleatorios empleados en la recuperación de anillas para estimar las relaciones entre las tasas de supervivencia y las tasas de cosecha en poblaciones bajo explotación
Increased population survival rate after an episode of seasonal exploitation is considered a type of compensatory population response. Lack of an increase is interpreted as evidence that exploitation results in added annual mortality in the population. Despite its importance to management of exploited species, there are limited statistical techniques for comparing relative support for these two alternative models. For exploited bird species, the most common technique is to use a fixed effect, deterministic ultrastructure model incorporated into band recovery models to estimate the relationship between harvest and survival rate. We present a new likelihood–based technique within a framework that assumes that survival and harvest are random effects that covary through time. We conducted a Monte Carlo simulation study under this framework to evaluate the performance of these two techniques. The ultrastructure models performed poorly in all simulated scenarios, due mainly to pathological distributional properties. The random effects estimators and their associated estimators of precision had relatively small negative bias under most scenarios, and profile likelihood intervals achieved nominal coverage. We suggest that the random effects estimation method approach has many advantages compared to the ultrastructure models, and that evaluation of robustness and generalization to more complex population structures are topics for additional research.El aumento en la tasa de supervivencia poblacional ocurrido tras un episodio de explotación estacional se considera como un tipo de respuesta compensatoria por parte de la población. La ausencia de un aumento se interpreta como una evidencia de que la explotación se traduce en una mayor mortalidad anual de la población. Pese a su importancia para la gestión de especies bajo explotación, sólo se dispone de un número limitado de técnicas estadísticas que permiten comparar el apoyo relativo que reciben estos dos modelos alternativos. Para las especies de aves bajo explotación, la técnica más habitual consiste en utilizar un modelo de efectos fijos, de ultraestructura determinista, incorporado a los modelos de recuperación de anillas para estimar la relación entre la tasa de cosecha y la tasa de supervivencia. En el presente estudio explicamos cómo emplear una nueva técnica basada en la razón de verosimilitud, en un marco que asume que la supervivencia y la cosecha son efectos aleatorios que covarían a lo largo del tiempo. Para ello, llevamos a cabo un estudio bajo dicho marco utilizando la simulación Monte Carlo, con objeto de evaluar el rendimiento de las dos técnicas mencionadas. El rendimiento de los modelos ultraestructurales fue bastante deficiente en todos los escenarios simulados, obedeciendo, principalmente, a propiedades distribucionales patológicas. Los estimadores de efectos aleatorios y sus estimadores de precisión asociados presentaron un sesgo relativamente pequeño en la mayor parte de los escenarios, mientras que los intervalos de verosimilitud del perfil alcanzaron una cobertura nominal. Sugerimos que el planteamiento basado en el método de estimación mediante modelos de efectos aleatorios brinda numerosas ventajas en comparación con los modelos ultraestructurales, y que la evaluación de la robustez y la generalización a estructuras poblacionales más complejas constituyen temas para una investigación adicional
EFFECT OF AVITROL BAITING ON BIRD DAMAGE TO RIPENING SUNFLOWER WITHIN A 144-SECTION BLOCK OF NORTH DAKOTA
The chemical frightening agent 4-aminopyridine (4-AP) has been repeatedly tested as a means of protecting both ripening corn (De Grazio et al. 1971, 1972; Besser et al. 1973; Besser 1976; Dolbeer et al. 1976; Stickley et al. 1972, 1976; Woronecki et al. 1979) and sunflower (Besser and Guarino 1976; Besser and Pfeifer 1978; Henne et al. 1979; Besser et al. in press) from depredating blackbirds. It was reported that less than one percent of a flock need ingest the treated baits and respond with distress symptoms in order to move birds from a corn field (De Grazio et al. 1972) or even shift roosting aggregations from night roosts (Cummings 1979). However, there is still conflicting evidence as to whether frightened blackbirds will subsequently avoid nearby fields, or even the same treated fields, resulting in efficient protection. The efficacy of 4-AP has not been resolved because of questions about the presentation and formulation of the treated baits and the difficulty of conducting a valid, unambiguous field test. This study was a large-scale evaluation of AvitroⓇ (HCI) FC-Corn Chops-99S1, where all commercial sunflower fields were monitored within a 144-sq mi block centered around a major concentration of roosting blackbirds; and all those fields with significant bird pressure were baited. The test was designed to answer two questions: can selective baiting (1) reduce damage overall when compared with pre-treatment damage from 1981, and (2) disperse it within the block? In other words, can the treatment keep blackbirds out of preferred fields? If so, is the result an overall reduction in damage within the surrounding area, or is it a redistribution of the damage
Reducing sugary drink intake through youth empowerment: results from a pilot-site randomized study
BACKGROUND: Efficacious strategies to reduce sugar-sweetened beverage (SSB) consumption among youth are needed. This pilot study assessed the feasibility and preliminary efficacy of a community-based youth empowerment intervention to reduce SSB consumption and obesity risk among a low-income, ethnically diverse sample of youth.
METHODS: The H2GO! intervention was pilot-tested in an afterschool setting (Boys and Girls Clubs (BGC)) in Massachusetts, USA. One site was randomized to receive the intervention; the other site received standard programming. Youth ages 9-12 years and their parents/caregivers were eligible to participate. A total of N = 110 parent-child pairs (N = 55 parent-child pairs per site) were recruited. The 6-week intervention consisted of group-based weekly sessions delivered by trained BGC staff and youth-led activities that engaged parents. Child outcomes included self-reported SSB and water intake and measured body mass index z scores (zBMI). Parent outcomes included self-reported SSB and water intake, SSB purchasing, and availability of SSBs at home. Outcomes were measured at baseline, 2 months, and 6 months. Generalized linear and logistic regression models were used to estimate intervention effects over time.
RESULTS: The final analytic study sample consisted of 100 child participants (38% Black, 20% Hispanic, 13% White, 12% Multiracial, 11% Asian) and 87 parent participants (78.2% female; 78.2% reporting eligibility for the free-or-reduced price lunch program). 6-month retention rates were \u3e /= 82%. Intervention attendance rates among intervention child participants (N = 51) averaged 78.1% (SD = 10.3). Over half (56.0%) of child participants were overweight or obese at baseline. Relative to the comparison site, intervention site child participants had decreased SSB intake (beta = - 1.64; 95% CI: 2.52, - 0.76), increased water intake (beta = 1.31; 95% CI: 0.38, 2.23), and decreased zBMI (- 0.23 units; 95% CI: - 0.31, - 0.14) over 6 months (p \u3c 0.001). Intervention parent participants also reported decreased SSB intake (beta = - 1.76; 95% CI: - 2.56, - 0.96) and increased water intake (beta = 1.75; 95% CI: 1.11, 2.40) than comparison parent participants at 6 months (p \u3c 0.001).
CONCLUSIONS: Findings demonstrate the potential of a youth empowerment intervention on reducing SSB intake and zBMI among a diverse sample. Findings will guide a larger cluster-randomized controlled trial to test intervention efficacy on preventing childhood obesity, as well as inform future interventions that aim to target additional diet and physical activity behaviors through youth empowerment.
TRIAL REGISTRATION: ClinicalTrials.gov NCT02890056 . Registered 31 August 2016
The development and validation of sexual health indicators of Canadians aged 16-24 years
Objectives: We developed and validated a set of self-administered, multidimensional indicators of sexual health among Canadians aged 16–24 years. Methods: This study used a mixed-method qualitative and quantitative approach to develop and validate indicators of sexual health. We used the four-stage Dillman method to identify, focus-test, pilot-test, and validate key metrics to measure sexual health. We collected quantitative data to validate the measures through a computer-assisted self-interviewing program among a purposive sample of 1,158 people aged 16–24 years recruited from four Canadian provinces. Results: The survey contained 75 items measuring five dimensions of sexual health: (1) physical, mental, emotional, and social well-being in relation to sexuality; (2) approach to sexuality; (3) sexual relationships; (4) sexual experiences; and (5) discrimination, coercion, and violence. Principal components analysis for composite measures found seven components with eigenvalues ≥ 1. The factor structure was stable across gender, age, size of area of residence, and language in which the survey was completed. Cronbach’s alpha coefficients ranged from 0.79 to 0.90. Indicators of condom use at last vaginal sex, protection self-efficacy, sexually transmitted infection/HIV testing self-efficacy, and sexual orientation also showed good construct validity. Conclusions: The indicators constituted a conceptually grounded survey that is easy for young adults to complete and contains valid, reliable, and psychometrically robust measures. The survey instrument provides a tool for future research to collect population-level data to measure and monitor trends in the sexual health of young people in Canada
Estimation of capture probabilities using generalized estimating equations and mixed effects approaches
Modeling individual heterogeneity in capture probabilities has been one of the most challenging tasks in capture-recapture studies. Heterogeneity in capture probabilities can be modeled as a function of individual covariates, but correlation structure among capture occasions should be taking into account. A proposed generalized estimating equations (GEE) and generalized linear mixed modeling (GLMM) approaches can be used to estimate capture probabilities and population size for capture-recapture closed population models. An example is used for an illustrative application and for comparison with currently used methodology. A simulation study is also conducted to show the performance of the estimation procedures. Our simulation results show that the proposed quasi-likelihood based on GEE approach provides lower SE than partial likelihood based on either generalized linear models (GLM) or GLMM approaches for estimating population size in a closed capture-recapture experiment. Estimator performance is good if a large proportion of individuals are captured. For cases where only a small proportion of individuals are captured, the estimates become unstable, but the GEE approach outperforms the other methods
Therapeutic targeting of the NRF2 and KEAP1 partnership in chronic diseases
The transcription factor NF-E2 p45-related factor 2 (NRF2; encoded by NFE2L2) and its principal negative regulator, the E3 ligase adaptor Kelch-like ECH-associated protein 1 (KEAP1), are critical in the maintenance of redox, metabolic and protein homeostasis, as well as the regulation of inflammation. Thus, NRF2 activation provides cytoprotection against numerous pathologies including chronic diseases of the lung and liver; autoimmune, neurodegenerative and metabolic disorders; and cancer initiation. One NRF2 activator has received clinical approval and several electrophilic modifiers of the cysteine-based sensor KEAP1 and inhibitors of its interaction with NRF2 are now in clinical development. However, challenges regarding target specificity, pharmacodynamic properties, efficacy and safety remain.This work was supported by grants SAF2015-71304-REDT and SAF2016-76520-R from the Spanish Ministry Economy and Competitiveness; P_37_732/2016 REDBRAIN from the European Regional Development Fund; Competitiveness Operational Program 2014–2020; US National Institutes of Health grant R35 CA197222; Cancer Research UK grant C20953/A18644; Medical
Research Council grant MR/N009851/1; Biotechnology and Biological Sciences Research Council grant BB/L01923X/1; Tenovus Scotland grant T17/14; and grant 275147 from the Academy of Finland, Sigrid Juselius Foundation and Finnish Cancer Foundation.Peer reviewe
Multivariate morphometric analysis of Apis cerana of southern mainland Asia
Multivariate morphometric analyses were performed on a series of worker honeybees, Apis cerana, representing 557 colonies from all of southern mainland Asia extending from Afghanistan to Vietnam south of the Himalayas. Scores from the principal components analysis revealed five statistically separable but not entirely distinct morphoclusters of bees: (1) the Hindu Kush, Kashmir, N. Myanmar, N. Vietnam and S. China; (2) Himachal Pradesh region of N. India; (3) N. India, Nepal; (4) central and S. Myanmar and Vietnam, Cambodia, Thailand, S. China and peninsular Malaysia; (5) central and S. India. The major morphoclusters are distributed coherently with the different climatic zones of the region. While populations are definable, nomenclatural adjustments remain for the future
Recent Borexino results and prospects for the near future
The Borexino experiment, located in the Gran Sasso National Laboratory, is an
organic liquid scintillator detector conceived for the real time spectroscopy
of low energy solar neutrinos. The data taking campaign phase I (2007 - 2010)
has allowed the first independent measurements of 7Be, 8B and pep fluxes as
well as the first measurement of anti-neutrinos from the earth. After a
purification of the scintillator, Borexino is now in phase II since 2011. We
review here the recent results achieved during 2013, concerning the seasonal
modulation in the 7Be signal, the study of cosmogenic backgrounds and the
updated measurement of geo-neutrinos. We also review the upcoming measurements
from phase II data (pp, pep, CNO) and the project SOX devoted to the study of
sterile neutrinos via the use of a 51Cr neutrino source and a 144Ce-144Pr
antineutrino source placed in close proximity of the active material.Comment: 8 pages, 11 figures. To be published as proceedings of Rencontres de
Moriond EW 201
Search for the lepton-family-number nonconserving decay \mu -> e + \gamma
The MEGA experiment, which searched for the muon- and electron-number
violating decay \mu -> e + \gamma, is described. The spectrometer system, the
calibrations, the data taking procedures, the data analysis, and the
sensitivity of the experiment are discussed. The most stringent upper limit on
the branching ratio of \mu -> e + \gamma) < 1.2 x 10^{-11} was obtained
- …