Bioestadística : princípios y procedimientos / Robert G. D. Steel, James H. Torrie

SERBIULA (sistema Librum 2.0)
Source: OAI

ABSTRACT Traducción de: Principles and procedures of statistics : a biomedical approach Incluye índice

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    Florida Entomologist 09/2009; DOI:10.1653/0015-4040(2006)89[524:EOHBNH]2.0.CO;2 · 1.06 Impact Factor
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    ABSTRACT: The importance of agroforestry systems as carbon sinks has recently been recognized due to the need of climate change mitigation. The objective of this study was to compare the carbon content in living biomass, soil (0–10, 10–20, 20–30cm in depth), dead organic matter between a set of non-agroforestry and agroforestry prototypes in Chiapas, Mexico where the carbon sequestration programme called Scolel’te has been carried out. The prototypes compared were: traditional maize (rotational prototype with pioneer native trees evaluated in the crop period), Taungya (maize with timber trees), improved fallow, traditional fallow (the last three rotational prototypes in the crop-free period), Inga-shade-organic coffee, polyculture-shade organic coffee, polyculture-non-organic coffee, pasture without trees, pasture with live fences, and pasture with scattered trees. Taungya and improved fallow were designed agroforestry prototypes, while the others were reproduced traditional systems. Seventy-nine plots were selected in three agro-climatic zones. Carbon in living biomass, dead biomass, and soil organic matter was measured in each plot. Results showed that carbon in living biomass and dead organic matter were different according to prototype; while soil organic carbon and total carbon were influenced mostly by the agro-climatic zone (P<0.01). Carbon density in the high tropical agro-climatic zone (1,000m) was higher compared to the intermediate and low tropical agro-climatic zones (600 and 200m, respectively, P<0.01). All the systems contained more carbon than traditional maize and pastures without trees. Silvopastoral systems, improved fallow, Taungya and coffee systems (especially polyculture-shade coffee and organic coffee) have the potential to sequester carbon via growing trees. Agroforestry systems could also contribute to carbon sequestration and reducing emissions when burning is avoided. The potential of organic coffee to maintain carbon in soil and to reduce emissions from deforestation and ecosystem degradation (REDD) is discussed.
    Agroforestry Systems 01/2010; 78(1):39-51. DOI:10.1007/s10457-009-9247-5 · 1.24 Impact Factor
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    ABSTRACT: Introduction: Pelargonium peltatum (L.) L'Her (ivy geranium) is widely used in natural medicine for the treatment of oral disease, but its pharmacological properties, antibacterial activity and phytoconstituent composition are still unknown. Objective: carry out a comparative study of the in vitro antibacterial activity of the aqueous extract obtained from leaves of Pelargonium peltatum (L.) L'Her (ivy geranium) against Streptococcus mutans, Streptococcus sanguis and Streptococcus mitis versus chlorhexidine. Methods: the agar diffusion method was used for the antibacterial assay. A study was conducted of 18 samples of microorganisms from the above-mentioned species, isolated from patients cared for at a dental clinic. Six different concentrations were prepared of the aqueous extract to compare antibacterial activity versus the chlorhexidine gargle. Preliminary phytochemical analysis was conducted by drop assay. The data obtained were subjected to statistical analyses such as mean and dispersion estimators, unifactorial analysis of variance and Tukey's test. Results: the highest antibacterial activity against the three species of Streptococcus was obtained with the 400 mg/ml concentration, and the lowest with the 25 mg/ml concentration of the aqueous extract, in comparison with chlorhexidine, with a similar effect to the 200 mg/ml concentration. The preliminary phytochemical assay revealed the presence of flavonoids, tannins, steroids, anthocyanins and saponins. Conclusions: the aqueous extract of Pelargonium peltatum has antibacterial activity against Streptococcus mutans, Streptococcus mitis and Streptococcus sanguis. Key words: antibacterial activity, Pelargonium peltatum (L.) L'Her, Streptococcus mutans, Streptococcus sanguis, Streptococcus mitis, chlorhexidine.
    Revista Cubana de Plantas Medicinales 05/2013; 18(02):224-236.