1,650 research outputs found

    Improved Randomization Tests for a Class of Single-Case Intervention Designs

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    Forty years ago, Eugene Edgington developed a single-case AB intervention design-and-analysis procedure based on a random determination of the point at which the B phase would start. In the present simulation studies encompassing a variety of AB-type contexts, it is demonstrated that by also randomizing the order in which the A and B phases are administered, a researcher can markedly increase the procedure’s statistical power

    An Improved Two Independent-Samples Randomization Test for Single-Case AB-Type Intervention Designs: A 20-Year Journey

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    Detailed is a 20-year arduous journey to develop a statistically viable two-phase (AB) single-case two independent-samples randomization test procedure. The test is designed to compare the effectiveness of two different interventions that are randomly assigned to cases. In contrast to the unsatisfactory simulation results produced by an earlier proposed randomization test, the present test consistently exhibited acceptable Type I error control under various design and effect-type configurations, while at the same time possessing adequate power to detect moderately sized intervention-difference effects. Selected issues, applications, and a multiple-baseline extension of the two-sample test are discussed

    Novel Microscopic Mechanism of Intermixing during Growth on Soft Metallic Substrates

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    Generic computer simulations using empiric interatomic potentials suggest a new, collective mechanism that could be responsible for mixing at heteroepitaxial interfaces. Even if single adsorbate atoms diffuse by hopping on the substrate surface and do not mix at the terraces, two-dimensional islands formed by nucleation may become unstable above a certain critical size and explode upwards forming clusters of several atomic layers. This process is accompanied by strong distortions of the underlying atomic layers, and on soft materials it can result in surface etching and incorporation of substrate atoms into the islands.Fil: Gomez, Liliana Maria. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; ArgentinaFil: Slutzky, Claudia Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Ferron, Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: de la Figuera, J.. Sandia National Laboratories; Estados UnidosFil: Camarero, J.. Universidad Autónoma de Madrid; EspañaFil: Vazquez de Parga, A.. Universidad Autónoma de Madrid; EspañaFil: de Miguel, J.J.. Universidad Autónoma de Madrid; EspañaFil: Miranda, R.. Universidad Autónoma de Madrid; Españ

    Características da madeira de Populus sp. e Platanus sp.

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    bitstream/CNPF-2009-09/30393/1/com_tec52.pd

    The synzootic potential of common epidemics in chamois populations

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    Altres ajuts: acords transformatius de la UABSouthern chamois (Rupicapra pyrenaica) is a medium-sized and gregarious mountain ungulate with populations affected by periodic outbreaks of border disease virus (BD), infectious keratoconjunctivitis (IKC), and sarcoptic mange (SM). Even though the impact of each disease on chamois populations has been described in detail, there is a lack of information about the potential impact of concomitant epidemics and the synzootic potential (co-occurring enzootic or epizootic processes producing worse health outcomes in wildlife) on chamois populations. Furthermore, whether a specific order of apparition of epidemics is more or less harmful for the host population is practically unknown not only for chamois but also for most mammal populations. Using a population viability analysis (PVA), we studied the consequences of multiple disease outbreaks with synzootic potential on growth rates and probabilities of extinction of virtual populations exposed to hard winters, density dependence, and co-occurring BD, IKC, and SM outbreaks. Such infections are not under cross-immunity nor density-dependent processes and thus are supposed to affect population demography independently. Heavy snowfalls are also likely to occur in our simulated populations. Our simulations showed that a second outbreak, even caused by a low virulent pathogen, causes an increase in the probability of extinction of the host population with regard to the first outbreak. IKC-BD- and SM-BD-affected populations had a higher risk of becoming extinct in 50 years confirming the extra risk of multiple outbreaks on the viability of the affected populations

    Comment on: "The treatment of sarcoptic mange in wildlife: a systematic review"

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    This letter comments on the article "The treatment of sarcoptic mange in wildlife: a systematic review" published in Parasites & Vectors 2019, 12:99, and discusses the limitations in the use of endectocides for scabies control in free-ranging wildlife. The ecological impact and drug resistance to ivermectin are also discussed. In our view, scabies control in free-ranging wildlife should be based preferably on population management measures, and whether to apply individual treatments to free-ranging populations should be considered very carefully and avoided where not absolutely warranted. $x 1756-330
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