University of Almería

About: University of Almería is a education organization based out in Almería, Spain. It is known for research contribution in the topics: Population & Context (language use). The organization has 4674 authors who have published 10905 publications receiving 233036 citations. The organization is also known as: University of Almeria & Universidad de Almería.

A parallel algorithm for Bayesian network structure learning from large data sets

Abstract: This paper considers a parallel algorithm for Bayesian network structure learning from large data sets. The parallel algorithm is a variant of the well known PC algorithm. The PC algorithm is a constraint-based algorithm consisting of five steps where the first step is to perform a set of (conditional) independence tests while the remaining four steps relate to identifying the structure of the Bayesian network using the results of the (conditional) independence tests. In this paper, we describe a new approach to parallelization of the (conditional) independence testing as experiments illustrate that this is by far the most time consuming step. The proposed parallel PC algorithm is evaluated on data sets generated at random from five different real-world Bayesian networks. The algorithm is also compared empirically with a process-based approach where each process manages a subset of the data over all the variables on the Bayesian network. The results demonstrate that significant time performance improvements are possible using both approaches.

Spanish adaptation of the acceptance and action questionnaire (AAQ)

Abstract: In this paper, we present the Spanish adaptation of the Acceptance and Action Questionnaire (AAQ). Hayes et al. (2000) developed the AAQ to assess experiential avoidance and psychological acceptance, two key concepts of the Acceptance and Commitment Therapy. We evaluate its psychometric properties in clinical and non- clinical sample. The results suggest that -as in the English original version- the Spanish AAQ is an internally consistent and valid scale, which is useful in the measurement of experiential avoidance and psychological acceptance in our population.

Poly(β-hydroxybutyric acid) thermoplastic production by Alcaligenes latus : Behavior of fed-batch cultures

Abstract: Fed-batch culture of Alcaligenes latus, ATCC 29713, was investigated for producing the intracellular bioplastic poly(β–hydroxybutyric acid), PHB. Constant rate feeding, exponentially increasing feeding rate, and pH-stat fed batch methods were evaluated. pH-stat fed batch culture reduced or delayed accumulation of the substrate in the broth and led to significantly enhanced PHB productivity relative to the other modes of feeding. Presence of excessive substrate appeared to inhibit PHB synthesis, but not the production of cells. In fed-batch culture, the maximum specific growth rate (0.265 h−1) greatly exceeded the value (0.075 h−1) previously observed in batch culture of the same strain. Similarly, the maximum PHB production rate (up to 1.15 g · l−1 · h−1) was nearly 8-fold greater than values observed in batch operations. Fed-batch operation was clearly superior to batch fermentation for producing PHB. A low growth rate was not a prerequisite for PHB accumulation, but a reduced or delayed accumulation of substrate appeared to enhance PHB accumulation. Under the best conditions, PHB constituted up to 63% of dry cell mass after 12 h of culture. The average biomass yield coefficient on sucrose was about 0.35, or a little less than in batch fermentations. The highest PHB concentrations attained were about 18 g · l−1.

Leaf litter breakdown in a Mediterranean stream characterised by travertine precipitation

Abstract: 1. Breakdown of four leaf species (Platanus orientalis, Populus nigra, Salix atrocinerea, Rubus ulmifolius) was studied in a Mediterranean second-order stream characterised by abundant travertine precipitation, a history of fire in its catchment, and a recently revegetated alluvial corridor. 2. Compared to breakdown rates reported in the literature for congeneric species, breakdown of the four species was slow (k = 0.0024–0.0069 day−1 for the tree species, and 0.0103 and 0.0111 day−1 for Rubus), in spite of high water temperatures, indicating that the travertine layer that quickly covered submerged leaves impeded decomposer activity and physical fragmentation losses. 3. Breakdown rates nevertheless differed between leaf species in a predictable manner, suggesting that the observed mass loss was largely due to biological processes. 4. The observed tendency towards increasing leaf nitrogen and phosphorus concentrations during breakdown suggests that microorganisms were actively involved in leaf breakdown; however, this interpretation must be viewed with caution because of potentially confounding effects by nutrients contained in the travertine layer. 5. Leaf breakdown of the three indigenous species was faster than that of the exotic species P. orientalis. Due to the recalcitrance of its leaves, the frequent use of Platanus in revegetation schemes following the destruction of indigenous vegetation by fire, exacerbates the negative effect of travertine precipitation on leaf breakdown and, by extension, energy flow in Mediterranean karst streams.