University of Alcalá

About: University of Alcalá is a education organization based out in Alcalá de Henares, Spain. It is known for research contribution in the topics: Population & Context (language use). The organization has 10795 authors who have published 20718 publications receiving 410089 citations. The organization is also known as: University of Alcala & University of Alcala de Henares.

Effect of cytochalasin A on apical growth, actin cytoskeleton organization and enzyme secretion in Aspergillus nidulans

Abstract: Summary: The role of actin in apical growth and enzyme secretion in the filamentous fungus Aspergillus nidulans was studied by treating the hyphae with cytochalasin A (CA), which inhibits actin polymerization. Indirect immunofluorescence microscopy revealed actin at the tips of main hyphae and branches, and at the sites of developing septa. CA inhibited the growth of the fungus and changed the growth pattern of hyphal tips from cylindrical tubes to spherical beads. The regions with swellings showed no actin fluorescence, and neither was actin seen in association with septa. After 4 h exposure, hyphae were able to resume the normal tip growth pattern in the presence of CA for a short period of time and new cylindrical hyphae, with actin fluorescence at the apex, emerged from the swollen tips. Later, the tips of the hyphae swelled again, which led to a beaded apperance. We also studied the effect of CA on the secretion of α- and β-galactosidase. α-Galactosidase is secreted into the culture medium, whereas β-galactosidase remains in the mycelium, with part of its activity bound to the cell wall. When A. nidulans mycelium was incubated in the presence of CA, a reduction in the secretion of α-galactosidase into the culture medium and a decrease in the α- and β-galactosidase activities bound to the cell wall was detected. However, the CA dose used for the hyphae did not modify the secretion of the enzymes from protoplasts. Results described here provide evidence that a polymerized actin cytoskeleton is required for normal apical growth, hyphal tip shape and polarized enzyme secretion in A. nidulans. Cytochalasin-induced disruptions of the actin cytoskeleton could result in the alterations of apical growth and inhibition of enzyme secretion observed by blocking secretory vesicle transport to the apex.

Toward Prevention of Pipeline Integrity Threats Using a Smart Fiber-Optic Surveillance System

Abstract: This paper presents the first available report in the literature of a system aimed at the detection and classification of threats in the vicinity of a long gas pipeline. The system is based on phase-sensitive optical time-domain reflectometry technology for signal acquisition and pattern recognition strategies for threat identification. The system operates in two different modes: 1) machine+activity identification, which outputs the activity being carried out by a certain machine; and 2) threat detection, aimed at detecting threats no matter what the real activity being conducted is. Different strategies dealing with position selection and normalization methods are presented and evaluated using a rigorous experimental procedure on realistic field data. Experiments are conducted with $\text{eight}$ machine+activity pairs, which are further labeled as threat or nonthreat for the second mode of the system. The results obtained are promising given the complexity of the task and open the path to future improvements toward fully functional pipeline threat detection systems operating in real conditions.

Labour Market Assimilation of Immigrants in Spain: Employment at the Expense of Bad Job-Matches?.

Abstract: Spain has traditionally been known as a country of emigrants. In the last decade, however, Spain has experienced unprecedented levels of immigration from three areas: Latin America, Africa, and Eastern Europe. In this paper, we study the behavior of recent immigrants in the Spanish labour market, identifying the major differences compared to the native population and tracking whether these differences fade away over the years. With this objective, we focus on four labour market outcomes: labour supply, unemployment, incidence of overeducation, and incidence of temporary contracts. Results show that, compared to natives, immigrants face initially higher participation rates, higher unemployment rates, higher incidence of overeducation and higher incidence of temporary contracts. However, five years after their arrival we could broadly say that participation rates start to converge to native rates, unemployment rates decrease to levels even lower than those of natives, and the incidence of temporary contracts and overeducation remains constant: no reduction of the gap with Spanish workers is observed. Therefore, we conclude that the Spanish labour market is managing to absorb the so-called "immigration boom", but at the expense of allocating immigrants in bad job-matches.

A new grouping genetic algorithm for clustering problems

Abstract: Highlights? A hybrid grouping-encoding algorithm for clustering problems is presented. ? Details on the encoding, operators and parallelization are given. ? Results in synthetic and real clustering problems are provided. In this paper we present a novel grouping genetic algorithm for clustering problems. Though there have been different approaches that have analyzed the performance of several genetic and evolutionary algorithms in clustering, the grouping-based approach has not been, to our knowledge, tested in this problem yet. In this paper we fully describe the grouping genetic algorithm for clustering, starting with the proposed encoding, different modifications of crossover and mutation operators, and also the description of a local search and an island model included in the algorithm, to improve the algorithm's performance in the problem. We test the proposed grouping genetic algorithm in several experiments in synthetic and real data from public repositories, and compare its results with that of classical clustering approaches, such as K-means and DBSCAN algorithms, obtaining excellent results that confirm the goodness of the proposed grouping-based methodology.