The performance of three ordination methods

The performance of robust principal component analysis (RPCA), detrended correspondence analysis (DCA) and non-metric multidimensional scaling (NMDS) with two demersal fish data sets were assessed in terms of their stability to bootstrap-generated sample variation and the method’s ability to reflect a well-known depth gradient. Stability was assessed for both species and site orderings and configurations, using scaled rank variance (SRV) and Spearman (q) and Procrustes correlations (t0). The NMDS site and species orderings showed the highest stability. DCA performed best in terms of site ordination stability, but NMDS performed best in terms of species ordination stability. In terms of matching the expected ecological variation, NMDS was the most sensitive method for the wider-depth gradient data and DCA was the most sensitive for the narrower-depth gradient data. According to the sensitivity and informative power criteria associated with the stability assessment, t0 was the best methodological approach for site ordinations, and SRV for species ordinations

Popularity in Facebook Pages: What role network structural variables play?

Facebook pages (FP) are meeting points between events and actors in virtual social networks (RSV) of this platform. Companies and events bring together actors that participate through the online expression mechanisms that are enabled, through reactions, tagging, photo posting, liking, comments, etc. These interactions form online contact networks. We propose to investigate structural variables of the networks captured online with structural variables of these networks. We found that various structural variables related to concentration or disconnection between nodes are negatively associated with popularity measured by the number of likes, on the other hand, the most popular FPs associated with the media (radio and news).Facebook pages (FP) are meeting points between events and actors in virtual social networks (RSV) of this platform. Companies and events bring together actors that participate through the online expression mechanisms that are enabled, through reactions, tagging, photo posting, liking, comments, etc. These interactions form online contact networks. We propose to investigate structural variables of the networks captured online with structural variables of these networks. We found that various structural variables related to concentration or disconnection between nodes are negatively associated with popularity measured by the number of likes, on the other hand, the most popular FPs associated with the media (radio and news)

Effects of the presence of cellulose and curaua fibers on the thermal and mechanical properties of eco-composites based on cellulose acetate

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOLos materiales eco-compósitos han obtenido el interés de la academia, debido a sus características amigables al medio ambiente. En este trabajo, se prepararon dos grupos de eco-compósitos con matriz de acetato de celulosa, reforzados con fibras de celulos172533546FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO2010/02098-02010/17804-7Los autores agradecen el financiamiento de los proyectos CONACYT 251504 y 264110. Además,se agradece a EMBRAPA por donar las fibras y aFAPESP (2010/02098-0 y 2010/17804-7

Extension of the characteristic equation to absorption chillers with adiabatic absorbers

Various researchers have developed models of conventional H2O–LiBr absorption machines with the aim of predicting their performance. In this paper, the methodology of characteristic equations developed by Hellmann et al. (1998) is applied. This model is able to represent the capacity of single effect absorption chillers and heat pumps by means of simple algebraic equations. An extended characteristic equation based on a characteristic temperature difference has been obtained, considering the facility features. As a result, it is concluded that for adiabatic absorbers a subcooling temperature must be specified. The effect of evaporator overflow has been characterized. Its influence on cooling capacity has been included in the extended characteristic equation. Taking into account the particular design and operation features, a good agreement between experimental performance data and those obtained through the extended characteristic equation has been achieved at off-design operation. This allows its use for simulation and control purposes

Confined dynamics in poly(ethylene terephthalate): A coherent and incoherent neutron scattering study

We show that the combination of dielectric relaxation with neutron spin echo and incoherent neutron backscattering measurements performed in deuterated and protonated poly(ethylene terephthalate) suggests that the intrinsic dynamics of semicrystalline polymers occurs in an homogeneous scenario, similar to that valid to describe the dynamics of totally amorphous polymers. The quasielastic neutron scattering data are satisfactorily described by a theoretical model that considers that the proton mobility follows a random jump-diffusion in a restricted environment

Estado de las mutaciones asociadas a las resistencias del VHB

Debido a que la Hepatitis por VHB es una Enfermedad de larga evolución, y los antivirales utilizados fácilmente generan resistencias. Es por lo que hemos detectado las mutaciones asociadas a la resistencia a los antivirales mas frecuentemente utilizados (Adefovir y Lamivudina) viendo además la evolución de estas resistencia

Wavelet analysis of epileptic spikes

Interictal spikes and sharp waves in human EEG are characteristic signatures of epilepsy. These potentials originate as a result of synchronous, pathological discharge of many neurons. The reliable detection of such potentials has been the long standing problem in EEG analysis, especially after long-term monitoring became common in investigation of epileptic patients. The traditional definition of a spike is based on its amplitude, duration, sharpness, and emergence from its background. However, spike detection systems built solely around this definition are not reliable due to the presence of numerous transients and artifacts. We use wavelet transform to analyze the properties of EEG manifestations of epilepsy. We demonstrate that the behavior of wavelet transform of epileptic spikes across scales can constitute the foundation of a relatively simple yet effective detection algorithm.Comment: 4 pages, 3 figure