Showing papers by "University of Alicante published in 2010"

Alien species in the Mediterranean Sea by 2010. A contribution to the application of European Union's Marine Strategy Framework Directive (MSFD). Part I. Spatial distribution

Abstract: The state-of-art on alien species in the Mediterranean Sea is presented, making distinctions among the four subregions defined in the EU Marine Strategy Framework Directive: (i) the Western Mediterranean Sea (WMED); (ii) the Central Mediterranean Sea (CMED); (iii) the Adriatic Sea (ADRIA); and (iv) the Eastern Mediterranean Sea (EMED). The updated checklist (December 2010) of marine alien species within each subregion, along with their acclimatization status and origin, is provided. A total of 955 alien species is known in the Mediterranean, the vast majority of them having being introduced in the EMED (718), less in the WMED (328) and CMED (267) and least in the Adriatic (171). Of these, 535 species (56%) are established in at least one area. Despite the collective effort of experts who attempted in this work, the number of introduced species remains probably underestimated. Excluding microalgae, for which knowledge is still insufficient, aliens have increased the total species richness of the Mediterranean Sea by 5.9%. This figure should not be directly read as an indication of higher biodiversity, as spreading of so many aliens within the basin is possibly causing biotic homogenization. Thermophilic species, i.e. Indo-Pacific, Indian Ocean, Red Sea, Tropical Atlantic, Tropical Pacific, and circum(sub)tropical, account for 88.4% of the introduced species in the EMED, 72.8% in the CMED, 59.3% in the WMED and 56.1% in the Adriatic. Cold water species, i.e. circumboreal, N Atlantic, and N Pacific, make up a small percentage of the introduced species, ranging between 4.2% and 21.6% and being more numerous in the Adriatic and less so in the EMED. Species that are classified as invasive or potentially invasive are 134 in the whole of the Mediterranean: 108 are present in the EMED, 76 in the CMED, 53 in the Adriatic and 64 in the WMED. The WMED hosts most invasive macrophytes, whereas the EMED has the lion’s share in polychaetes, crustaceans, molluscs and fish.

Nonlocal Diffusion Problems

Abstract: Nonlocal diffusion problems arise in a wide variety of applications, including biology, image processing, particle systems, coagulation models, and mathematical finance. These types of problems are also of great interest for their purely mathematical content. This book presents recent results on nonlocal evolution equations with different boundary conditions, starting with the linear theory and moving to nonlinear cases, including two nonlocal models for the evolution of sandpiles. Both existence and uniqueness of solutions are considered, as well as their asymptotic behaviour. Moreover, the authors present results concerning limits of solutions of the nonlocal equations as a rescaling parameter tends to zero. With these limit procedures the most frequently used diffusion models are recovered: the heat equation, the $p$-Laplacian evolution equation, the porous media equation, the total variation flow, a convection-diffusion equation and the local models for the evolution of sandpiles due to Aronsson-Evans-Wu and Prigozhin. Readers are assumed to be familiar with the basic concepts and techniques of functional analysis and partial differential equations. The text is otherwise self-contained, with the exposition emphasizing an intuitive understanding and results given with full proofs. It is suitable for graduate students or researchers. The authors cover a subject that has received a great deal of attention in recent years. The book is intended as a reference tool for a general audience in analysis and PDEs, including mathematicians, engineers, physicists, biologists, and others interested in nonlocal diffusion problems.

High-Surface-Area Carbon Molecular Sieves for Selective CO2 Adsorption

Abstract: A series of carbon molecular sieves (CMSs) has been prepared, either as powders or monoliths, from petroleum pitch using potassium hydroxide as the activating agent. The CMS monoliths are prepared without the use of a binder based on the self-sintering ability of the mesophase pitch. Characterization results show that these CMSs combine a large apparent surface area (up to ca. 3100 m(2) g(-1)) together with a well-developed narrow microporosity (V(n) up to ca. 1.4 cm(3) g(-1)). The materials exhibit high adsorption capacities for CO(2) at 1 bar and 273 K (up to ca. 380 mg CO(2) g sorbent(-1)). To our knowledge, this is the best result obtained for CO(2) adsorption using carbon-based materials. Furthermore, although the CO(2) adsorption capacity for activated carbons has usually been considered lower than that of zeolites, the reported values exceed the total amount adsorbed on traditional 13X and 5A zeolites (ca. 230 mg and 180 mg CO(2) g sorbent(-1), respectively), under identical experimental conditions. Additionally, the narrow pore openings found in the CMS samples (ca. 0.4 nm) allows for the selective adsorption of CO(2) from molecules of similar dimensions (e.g., CH(4) and N(2)).

Marine reserves: fish life history and ecological traits matter.

Abstract: Marine reserves are assumed to protect a wide range of species from deleterious effects stemming from exploitation. However, some species, due to their ecological characteristics, may not respond positively to protection. Very little is known about the effects of life history and ecological traits (e.g., mobility, growth, and habitat) on responses of fish species to marine reserves. Using 40 data sets from 12 European marine reserves, we show that there is significant variation in the response of different species of fish to protection and that this heterogeneity can be explained, in part, by differences in their traits. Densities of targeted size-classes of commercial species were greater in protected than unprotected areas. This effect of protection increased as the maximum body size of the targeted species increased, and it was greater for species that were not obligate schoolers. However, contrary to previous theoretical findings, even mobile species with wide home ranges benefited from protection: the effect of protection was at least as strong for mobile species as it was for sedentary ones. Noncommercial bycatch and unexploited species rarely responded to protection, and when they did (in the case of unexploited bentho-pelagic species), they exhibited the opposite response: their densities were lower inside reserves. The use of marine reserves for marine conservation and fisheries management implies that they should ensure protection for a wide range of species with different life-history and ecological traits. Our results suggest this is not the case, and instead that effects vary with economic value, body size, habitat, depth range, and schooling behavior.

A survey on the role of negation in sentiment analysis

Abstract: This paper presents a survey on the role of negation in sentiment analysis. Negation is a very common linguistic construction that affects polarity and, therefore, needs to be taken into consideration in sentiment analysis. We will present various computational approaches modeling negation in sentiment analysis. We will, in particular, focus on aspects, such as level of representation used for sentiment analysis, negation word detection and scope of negation. We will also discuss limits and challenges of negation modeling on that task.

Firms in International Trade: Importers and Exporters Heterogeneity in the Italian Manufacturing Industry

Abstract: Combining data on structural characteristics and economic performance for a large sample of Italian firms with data on exporting and importing activity, we uncover evidence supporting recent theories on firm heterogeneity and international trade, together with some new facts. In particular, we find that importing is associated with substantial firm heterogeneity. First, we document that trade is more concentrated than employment and sales, and show that importing is even more concentrated than exporting both within sectors and along the sector- and country-extensive margins. Second, while supporting the fact that firms involved in both are the best performers, we also find that firms involved only in importing activities perform better than those involved only in exporting. Our evidence suggests there is a strong self-selection effect in the case of importers and the performance premia of internationalised firms correlate relatively more with the degree of geographical and sectoral diversification of imports.

Imaging structure sensitive catalysis on different shape-controlled platinum nanoparticles.

Abstract: The structure sensitive catalytic activity for oxygen reduction reaction (ORR) on shape-controlled Pt nanoparticles (NPs) is directly imaged using scanning electrochemical microscopy (SECM). We synthesize and compare four types of Pt NPs: spherical, cubic, hexagonal, and tetrahedral-octahedral. Our SECM images show the hexagonal Pt NPs displaying the highest activity for ORR in two acid electrolytes. Meanwhile, cubic and tetrahedral-octahedral NPs drastically change their activity depending on specific adsorption of the different anions in solution. The NPs morphology produces predominant crystallographic planes at the surface of these shape-controlled Pt NPs, which are responsible for their different catalytic activity. Our results translate the studies on Pt single crystal electrodes present in the literature into Pt NPs that are useful as a catalyst in real fuel cells.

Oxime-derived palladacycles as source of palladium nanoparticles.

Abstract: Oxime-derived palladacycles are very efficient and versatile pre-catalysts for a wide range of carbon–carbon bond coupling reactions in air, under very low loading conditions, and employing reagent-grade chemicals. This tutorial review presents the main achievements, advantages and limitations of oxime palladacycles as a source of highly active palladium nanoparticles for high-turnover catalyzed Heck, as well as other homo- and cross-coupling reactions usually carried out employing organic or aqueous solvents. Comparison with other ligandless Pd(II) catalysts is also presented. Recent advances to develop supported oxime-derived palladacycles in order to facilitate precatalyst recovery and reuse in cross-coupling reactions, especially under aqueous reaction conditions, are also discussed.

Diversity of CRISPR loci in Escherichia coli.

Abstract: CRISPR (clustered regularly interspaced short palindromic repeats) and CAS (CRISPR-associated sequence) proteins are constituents of a novel genetic barrier that limits horizontal gene transfer in prokaryotes by means of an uncharacterized mechanism. The fundamental discovery of small RNAs as the guides of the defence apparatus arose as a result of Escherichia coli studies. However, a survey of the system diversity in this species in order to further contribute to the understanding of the CRISPR mode of action has not yet been performed. Here we describe two CRISPR/CAS systems found in E. coli, following the analysis of 100 strains representative of the species' diversity. Our results substantiate different levels of activity between loci of both CRISPR types, as well as different target preferences and CRISPR relevances for particular groups of strains. Interestingly, the data suggest that the degeneration of one CRISPR/CAS system in E. coli ancestors could have been brought about by self-interference.

Membrane fluidity determines sensitivity of filamentous fungi to chitosan

Abstract: The antifungal mode of action of chitosan has been studied for the last 30 years, but is still little understood. We have found that the plasma membrane forms a barrier to chitosan in chitosan-resistant but not chitosan-sensitive fungi. The plasma membranes of chitosan-sensitive fungi were shown to have more polyunsaturated fatty acids than chitosan-resistant fungi, suggesting that their permeabilization by chitosan may be dependent on membrane fluidity. A fatty acid desaturase mutant of Neurospora crassa with reduced plasma membrane fluidity exhibited increased resistance to chitosan. Steady-state fluorescence anisotropy measurements on artificial membranes showed that chitosan binds to negatively charged phospholipids that alter plasma membrane fluidity and induces membrane permeabilization, which was greatest in membranes containing more polyunsaturated lipids. Phylogenetic analysis of fungi with known sensitivity to chitosan suggests that chitosan resistance may have evolved in nematophagous and entomopathogenic fungi, which naturally encounter chitosan during infection of arthropods and nematodes. Our findings provide a method to predict the sensitivity of a fungus to chitosan based on its plasma membrane composition, and suggests a new strategy for antifungal therapy, which involves treatments that increase plasma membrane fluidity to make fungi more sensitive to fungicides such as chitosan.

Multicomponent Synthesis of 1,2,3‐Triazoles in Water Catalyzed by Copper Nanoparticles on Activated Carbon

Abstract: Copper nanoparticles on activated carbon have been found to effectively catalyze the multicomponent synthesis of 1,2,3-triazoles from different azide precursors, such as organic halides, diazonium salts, anilines and epoxides in water. The first one-pot transformation of an olefin into a triazole is also described. The catalyst is easy to prepare, very versatile and reusable at a low copper loading.

Corneal volume, pachymetry, and correlation of anterior and posterior corneal shape in subclinical and different stages of clinical keratoconus.

Abstract: Purpose To evaluate the corneal volume, pachymetry, and correlation of anterior and posterior corneal shape in subclinical and clinical keratoconus. Setting Vissum Corporation, Alicante, Spain. Methods Eyes were placed into 1 of 4 groups as follows: keratoconus 2 (grade II), keratoconus 1 (grade I), subclinical (subclinical keratoconus), and control (normal eyes). All eyes had an ophthalmologic examination including corneal evaluation (curvature, elevation, asphericity, pachymetry, corneal volume) by rotating Scheimpflug imaging (Pentacam). The posterior–anterior corneal power ratio was also calculated. Results Seventy-one eyes (51 patients; aged 16 to 64 years) were evaluated. Astigmatism and keratometry of both corneal surfaces were statistically significantly higher in the keratoconus 1 and 2 groups ( P ≤.02). Posterior astigmatism was statistically significantly higher in the subclinical group than in the control group ( P = .01). A strong correlation ( r ≥−0.81) was found between anterior and posterior curvature in the normal and subclinical groups; the correlation was weaker in clinical keratoconus cases ( r ≤−0.56). The correlation in astigmatism between the anterior and posterior surface was good in all keratoconus groups ( r ≥0.81). The posterior–anterior corneal power ratio was significantly higher in the keratoconus 2 group than in the other groups ( P ≤.01). Pachymetric readings were progressively lower in eyes with subclinical, early, or moderate keratoconus ( P P = .04). Conclusion The correlation between anterior and posterior corneal curvature was lower in keratoconus, although the correlation between anterior and posterior astigmatism was maintained. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

The application of mixed methods in organisational research: a literature review

Abstract: Mixed methods research (the combined use of quantitative and qualitative methods in the same study) is becoming an increasingly popular approach in the discipline fields of sociology, psychology, education and health sciences. Calls for the integration of quantitative and qualitative research methods have been advanced in these fields. A key feature of mixed methods research is its methodological pluralism, which frequently results in research which provides broader perspectives than those offered by monomethod designs. The overall purpose and central premise of mixed methods is that the use of quantitative and qualitative approaches in combination provides a better understanding of research problems and complex phenomena than either approach alone. Despite calls for the combined use of quantitative and qualitative research in business and management studies, the use of mixed methods in business and management has seldom been studied. The purpose of this paper is to review the application of mixed methods research within organisational research. The study reported in this paper identifies the use of mixed methods in three organisational journals for the period 2003 to 2009: the Strategic Management Journal, Journal of Organizational Behavior and Organizational Research Methods. The landmark Tashakkori and Teddlie (2003) Handbook of mixed methods in social and behavioral research, played a pivotal role in providing both the visibility and credibility of mixed methods as a third methodological movement and since the publication of this seminal work the mixed methods movement has rapidly gained popularity. Business and management researchers need to be made aware of the growing use and acceptance of mixed methods research across business and organisational journals. This paper examines the main characteristics of mixed methods studies identified in the sample in terms of purposes and designs, and posits suggestions on the application of mixed methodologies.

Transition-Metal-Catalyzed Synthesis of Hydroxylated Arenes

Abstract: An overview of the recent bibliography in the transition-metal-catalyzed hydroxylation of aryl derivatives is presented. Two reaction protocols are considered: 1) C--H activation/hydroxylation and, 2) cross-coupling hydroxylation of aryl halides. The achievements and limitations for both procedures are described taking into consideration different metal catalyst/oxidant combinations.

Competitive strategy, structure and firm performance

Abstract: Purpose – Decisions about the design of the organization and the competitive strategy of a firm are very important in order to gain competitive advantage and to improve firm performance. The relationship between organizational structure, competitive strategy, and firm performance has usually been analyzed using the contingency approach. The objective of this paper is to extend the relevant empirical literature of the strategy‐structure‐performance paradigm by comparing the resource‐based view (RBV) with contingency theory. To that end, the paper seeks to examine how organizational structure affects firm performance, taking into account the relationship with competitive strategy.Design/methodology/approach – A sample of large Spanish firms was studied using the partial least squares (PLS) technique.Findings – The results support both the RBV and the contingency approach, but the RBV is more strongly supported. The findings show that organizational structure does not exert a direct influence on performance,...

Mechanistic studies of the 'blue' Cu enzyme, bilirubin oxidase, as a highly efficient electrocatalyst for the oxygen reduction reaction

Abstract: The ‘blue copper’ enzyme bilirubin oxidase from Myrothecium verrucaria shows significantly enhanced adsorption on a pyrolytic graphite ‘edge’ (PGE) electrode that has been covalently modified with naphthyl-2-carboxylate functionalities by diazonium coupling. Modified electrodes coated with bilirubin oxidase show electrocatalytic voltammograms for the direct, four-electron reduction of O2 by bilirubin oxidase with up to four times the current density of an unmodified PGE electrode. Electrocatalytic voltammograms measured with a rapidly rotating electrode (to remove effects of O2 diffusion limitation) have a complex shape (an almost linear dependence of current on potential below pH 6) that is similar regardless of how PGE is chemically modified. Importantly, the same waveform is observed if bilirubin oxidase is adsorbed on Au(111) or Pt(111) single-crystal electrodes (at which activity is short-lived). The electrocatalytic behavior of bilirubin oxidase, including its enhanced response on chemically-modified PGE, therefore reflects inherent properties that do not depend on the electrode material. The variation of voltammetric waveshapes and potential-dependent (O2) Michaelis constants with pH and analysis in terms of the dispersion model are consistent with a change in rate-determining step over the pH range 5–8: at pH 5, the high activity is limited by the rate of interfacial redox cycling of the Type 1 copper whereas at pH 8 activity is much lower and a sigmoidal shape is approached, showing that interfacial electron transfer is no longer a limiting factor. The electrocatalytic activity of bilirubin oxidase on Pt(111) appears as a prominent pre-wave to electrocatalysis by Pt surface atoms, thus substantiating in a single, direct experiment that the minimum overpotential required for O2 reduction by the enzyme is substantially smaller than required at Pt. At pH 8, the onset of O2 reduction lies within 0.14 V of the four-electron O2/2H2O potential.

Complete Genome Sequence of Crohn's Disease-Associated Adherent-Invasive E. coli Strain LF82

Abstract: BACKGROUND: Ileal lesions of Crohn's disease (CD) patients are abnormally colonized by pathogenic adherent-invasive Escherichia coli (AIEC) able to invade and to replicate within intestinal epithelial cells and macrophages. PRINCIPAL FINDINGS: We report here the complete genome sequence of E. coli LF82, the reference strain of adherent-invasive E. coli associated with ileal Crohn's disease. The LF82 genome of 4,881,487 bp total size contains a circular chromosome with a size of 4,773,108 bp and a plasmid of 108,379 bp. The analysis of predicted coding sequences (CDSs) within the LF82 flexible genome indicated that this genome is close to the avian pathogenic strain APEC_01, meningitis-associated strain S88 and urinary-isolated strain UTI89 with regards to flexible genome and single nucleotide polymorphisms in various virulence factors. Interestingly, we observed that strains LF82 and UTI89 adhered at a similar level to Intestine-407 cells and that like LF82, APEC_01 and UTI89 were highly invasive. However, A1EC strain LF82 had an intermediate killer phenotype compared to APEC-01 and UTI89 and the LF82 genome does not harbour most of specific virulence genes from ExPEC. LF82 genome has evolved from those of ExPEC B2 strains by the acquisition of Salmonella and Yersinia isolated or clustered genes or CDSs located on pLF82 plasmid and at various loci on the chromosome. CONCLUSION: LF82 genome analysis indicated that a number of genes, gene clusters and pathoadaptative mutations which have been acquired may play a role in virulence of AIEC strain LF82.

Sentiment Analysis in the News

Abstract: Recent years have brought a significant growth in the volume of research in sentiment analysis, mostly on highly subjective text types (movie or product reviews). The main difference these texts have with news articles is that their target is clearly defined and unique across the text. Following different annotation efforts and the analysis of the issues encountered, we realised that news opinion mining is different from that of other text types. We identified three subtasks that need to be addressed: definition of the target; separation of the good and bad news content from the good and bad sentiment expressed on the target; and analysis of clearly marked opinion that is expressed explicitly, not needing interpretation or the use of world knowledge. Furthermore, we distinguish three different possible views on newspaper articles ― author, reader and text, which have to be addressed differently at the time of analysing sentiment. Given these definitions, we present work on mining opinions about entities in English language news, in which we apply these concepts. Results showed that this idea is more appropriate in the context of news opinion mining and that the approaches taking this into consideration produce a better performance.

The Application of Mindfulness to Eating Disorders Treatment: A Systematic Review

Abstract: The present study is an exploratory examination of the efficacy of the application of mindfulness-based interventions to the treatment of eating disorders. It employs a systematic review technique in which terms from the Psychological Index Terms of the American Psychological Association (APA) were chosen and analyzed in conjunction with Boolean operators. Using data obtained by the online consultation of references from 12 different bibliographical databases, 8 studies were included in the systematic review. Each study reported satisfactory results, although trial qualities were variable and sample sizes were small. Nonetheless, the current study found initial evidence supporting the effectiveness of mindfulness-based interventions to the treatment of eating disorders. The application of mindfulness-based interventions to the treatment of eating disorders remains a promising approach worthy of further research.

Impregnated copper on magnetite: an efficient and green catalyst for the multicomponent preparation of propargylamines under solvent free conditions.

Abstract: Impregnated copper on magnetite is a versatile, inexpensive and simple catalyst for the selective multicomponent reaction of terminal alkynes, aldehydes and secondary amines to give the corresponding propargylamines with excellent yields. The catalyst can be easily recovered and reused by using a simple magnet. The process could be repeated up to ten times without losing its activity.