Showing papers by "University of Seville published in 2015"

The global threat of antimicrobial resistance: science for intervention

Abstract: In the last decade we have witnessed a dramatic increase in the proportion and absolute number of bacterial pathogens resistant to multiple antibacterial agents. Multidrug-resistant bacteria are currently considered as an emergent global disease and a major public health problem. The B-Debate meeting brought together renowned experts representing the main stakeholders (i.e. policy makers, public health authorities, regulatory agencies, pharmaceutical companies and the scientific community at large) to review the global threat of antibiotic resistance and come up with a coordinated set of strategies to fight antimicrobial resistance in a multifaceted approach. We summarize the views of the B-Debate participants regarding the current situation of antimicrobial resistance in animals and the food chain, within the community and the healthcare setting as well as the role of the environment and the development of novel diagnostic and therapeutic strategies, providing expert recommendations to tackle the global threat of antimicrobial resistance.

Grid-Connected Photovoltaic Systems: An Overview of Recent Research and Emerging PV Converter Technology

Abstract: Photovoltaic (PV) energy has grown at an average annual rate of 60% in the last five years, surpassing one third of the cumulative wind energy installed capacity, and is quickly becoming an important part of the energy mix in some regions and power systems. This has been driven by a reduction in the cost of PV modules. This growth has also triggered the evolution of classic PV power converters from conventional single-phase grid-tied inverters to more complex topologies to increase efficiency, power extraction from the modules, and reliability without impacting the cost. This article presents an overview of the existing PV energy conversion systems, addressing the system configuration of different PV plants and the PV converter topologies that have found practical applications for grid-connected systems. In addition, the recent research and emerging PV converter technology are discussed, highlighting their possible advantages compared with the present technology.

A systematic literature review on entrepreneurial intentions: citation, thematic analyses, and research agenda

Abstract: Entrepreneurial intention is a rapidly evolving field of research. A growing number of studies use entrepreneurial intention as a powerful theoretical framework. However, a substantial part of this research lacks systematization and categorization, and there seems to be a tendency to start anew with every study. Therefore, there is a need to take stock of current knowledge in this field. In this sense, this paper carries out a review of the literature on entrepreneurial intentions. A total of 409 papers addressing entrepreneurial intention, published between 2004 and 2013 (inclusive), have been analyzed. The purpose and contribution of this paper is to offer a clearer picture of the sub-fields in entrepreneurial intention research, by concentrating on two aspects. Firstly, it reviews recent research by means of a citation analysis to categorize the main areas of specialization currently attracting the attention of the academic community. Secondly, a thematic analysis is carried out to identify the specific themes being researched within each category. Despite the large number of publications and their diversity, the present study identifies five main research areas, plus an additional sixth category for a number of new research papers that cannot be easily classified into the five areas. Within those categories, up to twenty-five different themes are recognized. A number of research gaps are singled out within each of these areas of specialization, in order to induce new ways and perspectives in the entrepreneurial intention field of research that may be fruitful in filling these gaps.

Beyond species loss: The extinction of ecological interactions in a changing world

Abstract: Summary 1. The effects of the present biodiversity crisis have been largely focused on the loss of species. However, a missed component of biodiversity loss that often accompanies or even precedes species disappearance is the extinction of ecological interactions. 2. Here, we propose a novel model that (i) relates the diversity of both species and interactions along a gradient of environmental deterioration and (ii) explores how the rate of loss of ecological functions, and consequently of ecosystem services, can be accelerated or restrained depending on how the rate of species loss covaries with the rate of interactions loss. 3. We find that the loss of species and interactions are decoupled, such that ecological interactions are often lost at a higher rate. This implies that the loss of ecological interactions may occur well before species disappearance, affecting species functionality and ecosystems services at a faster rate than species extinctions. We provide a number of empirical case studies illustrating these points. 4. Our approach emphasizes the importance of focusing on species interactions as the major biodiversity component from which the ‘health’ of ecosystems depends.

Reported Foodborne Outbreaks Due to Fresh Produce in the United States and European Union: Trends and Causes

Abstract: The consumption of fruit and vegetables continues to rise in the United States and European Union due to healthy lifestyle recommendations. Meanwhile, the rate of foodborne illness caused by the consumption of these products remains high in both regions, representing a significant public health and financial issue. This study addresses the occurrence of reported foodborne outbreaks associated with fresh fruits and vegetables consumption in the United States and European Union during the period 2004–2012, where data are available. Special attention is paid to those pathogens responsible for these outbreaks, the mechanisms of contamination, and the fresh produce vehicles involved. Norovirus is shown to be responsible for most of the produce-related outbreaks, followed by Salmonella. Norovirus is mainly linked with the consumption of salad in the United States and of berries in the European Union, as demonstrated by the Multiple Correspondence Analysis (MCA). Salmonella was the leading cause of mult...

Copper-catalysed azide-alkyne cycloadditions (CuAAC): an update.

Abstract: The reactions of organic azides and alkynes catalysed by copper species represent the prototypical examples of click chemistry. The so-called CuAAC reaction (copper-catalysed azide-alkyne cycloaddition), discovered in 2002, has been expanded since then to become an excellent tool in organic synthesis. In this contribution the recent results described in the literature since 2010 are reviewed, classified according to the nature of the catalyst precursor: copper(I) or copper(II) salts or complexes, metallic or nano-particulated copper and several solid-supported copper systems.

Highly Efficient Perovskite Solar Cells with Tunable Structural Color

Abstract: The performance of perovskite solar cells has been progressing over the past few years and efficiency is likely to continue to increase However, a negative aspect for the integration of perovskite solar cells in the built environment is that the color gamut available in these materials is very limited and does not cover the green-to-blue region of the visible spectrum, which has been a big selling point for organic photovoltaics Here, we integrate a porous photonic crystal (PC) scaffold within the photoactive layer of an opaque perovskite solar cell following a bottom-up approach employing inexpensive and scalable liquid processing techniques The photovoltaic devices presented herein show high efficiency with tunable color across the visible spectrum This now imbues the perovskite solar cells with highly desirable properties for cladding in the built environment and encourages design of sustainable colorful buildings and iridescent electric vehicles as future power generation sources

Optimal Economical Schedule of Hydrogen-Based Microgrids With Hybrid Storage Using Model Predictive Control

Abstract: The electricity market rules determine the energy prices in the day-ahead market, matching offers from generators to bids from consumers. The unpredictability of renewable energy combined with the penalty deviations used in the regulation market makes it difficult for clean energy to play an important role in the electricity market. The high density of hydrogen as an energy storage system (ESS) appears to be one solution to the problems outlined. There is still not a perfect ESS, everyone has different limitations from the point of view of time autonomy, time response, degradation issues, or acquisition cost. The design of a hybrid energy storage management system emerges as a technological solution to the problems commented. The development of an optimal control for renewable energy microgrids with hybrid ESS is carried out using model predictive control (MPC). The MPC techniques allow maximizing the economical benefit of the microgrid, minimizing the degradation causes of each storage system, and fulfilling the different system constraints. In order to capture both continuous/discrete dynamics and switching between different operating conditions, the plant is modeled with the framework of mixed logic dynamic. The MPC problem is solved within mixed-integer quadratic programming.

Update of Guidelines on Laparoscopic (TAPP) and Endoscopic (TEP) Treatment of Inguinal Hernia (International Endohernia Society)

Abstract: Guidelines are the bridge between science and clinical practice [1]. Science is a dynamic process and it is continuously evolving. Consequently, there is a continual development of new insights necessitation updates of existing guidelines. For this update, the authors concentrated on studies with level of 1 and 2 evidence. All references are marked with the level of evidence, according to the Oxford classification. In general “Recommendation Grade D” does not constitute a recommendation, but in some instances it is shown in the text to indicate lack of quality data. We recommended all readers to download the original statements and recommendations [2], for fully appreciation of the Update Guidelines on Laparoscopic Hernia Surgery. Updates should include issues that were not yet sufficiently covered in the original guidelines or those which have gained increased clinical importance. For this reason, the Update includes four new chapters: single port surgery, convalescence, costs and training. The update process was started in March 2013. All the authors were requested to commence revision of their chapters between January 2009 and September 30th 2013. An Update Consensus Conference was held on October 23–26, 2013 in Windhoek/Namibia, following which, the first versions of the updates were presented to the delegates and extensively discussed. Based on these discussions the definite update was formulated and circulated for approval by all the involved experts.

A systematic literature review on entrepreneurial intentions: citation, thematic analyses, and research agenda

Abstract: Entrepreneurial intention is a rapidly evolving field of research. A growing number of studies use entrepreneurial intention as a powerful theoretical framework. However, a substantial part of this research lacks systematization and categorization, and there seems to be a tendency to start anew with every study. Therefore, there is a need to take stock of current knowledge in this field. In this sense, this paper carries out a review of the literature on entrepreneurial intentions. A total of 409 papers addressing entrepreneurial intention, published between 2004 and 2013 (inclusive), have been analyzed. The purpose and contribution of this paper is to offer a clearer picture of the sub-fields in entrepreneurial intention research, by concentrating on two aspects. Firstly, it reviews recent research by means of a citation analysis to categorize the main areas of specialization currently attracting the attention of the academic community. Secondly, a thematic analysis is carried out to identify the specific themes being researched within each category. Despite the large number of publications and their diversity, the present study identifies five main research areas, plus an additional sixth category for a number of new research papers that cannot be easily classified into the five areas. Within those categories, up to twenty-five different themes are recognized. A number of research gaps are singled out within each of these areas of specialization, in order to induce new ways and perspectives in the entrepreneurial intention field of research that may be fruitful in filling these gaps.

New insights into organic–inorganic hybrid perovskite CH3NH3PbI3 nanoparticles. An experimental and theoretical study of doping in Pb2+ sites with Sn2+, Sr2+, Cd2+ and Ca2+

Abstract: This paper presents the synthesis of the organic–inorganic hybrid perovskite, CH3NH3PbI3, doped in the Pb2+ position with Sn2+, Sr2+, Cd2+ and Ca2+. The incorporation of the dopants into the crystalline structure was analysed, observing how the characteristics of the dopant affected properties such as the crystalline phase, emission and optical properties. XRD showed how doping with Sn2+, Sr2+ and Cd2+ did not modify the normal tetragonal phase. When doping with Ca2+, the cubic phase was obtained. Moreover, DR-UV-Vis spectroscopy showed how the band gap decreased with the dopants, the values following the trend Sr2+ Cd2+ > Sr2+ for the tetragonal structure and Pb2+ > Ca2+ for the cubic phase. The electron localization function (ELF) analysis showed similar electron localizations for undoped and Sn2+-doped tetragonal structures, which were different from those doped with Sr2+ and Cd2+. Furthermore, when Cd2+ was incorporated, the Cd–I interaction was strengthened. For Ca2+ doping, the Ca–I interaction had a greater ionic nature than Cd–I. Finally, an analysis based on the non-covalent interaction (NCI) index is presented to determine the weak-type interactions of the CH3NH3 groups with the dopant and I atoms. To our knowledge, this kind of analysis with these hybrid systems has not been performed previously.

Fault Diagnosis of Electric Power Systems Based on Fuzzy Reasoning Spiking Neural P Systems

Abstract: This paper proposes a graphic modeling approach, fault diagnosis method based on fuzzy reasoning spiking neural P systems (FDSNP), for power transmission networks. In FDSNP, fuzzy reasoning spiking neural P systems (FRSN P systems) with trapezoidal fuzzy numbers are used to model candidate faulty sections and an algebraic fuzzy reasoning algorithm is introduced to obtain confidence levels of candidate faulty sections, so as to identify faulty sections. FDSNP offers an intuitive illustration based on a strictly mathematical expression, a good fault-tolerant capacity due to its handling of incomplete and uncertain messages in a parallel manner, a good description for the relationships between protective devices and faults, and an understandable diagnosis model-building process. To test the validity and feasibility of FDSNP, seven cases of a local subsystem in an electrical power system are used. The results of case studies show that FDSNP is effective in diagnosing faults in power transmission networks for single and multiple fault situations with/without incomplete and uncertain SCADA data, and is superior to four methods, reported in the literature, in terms of the correctness of diagnosis results.

Driving forces of Spain׳s CO2 emissions: A LMDI decomposition approach

Abstract: An extended version of the IPAT model and the ‘Kaya identity’ is used to assess the contribution of drivers of CO2 emissions for the 1995–2009 period. The paper carries out a multisector analysis based on the Log-Mean Divisia Index Method (LMDI I). The decomposition factors used are the Carbon Intensity factor (CI), the Energy Intensity factor (EI), the structural composition of Spain׳s economy (Economy Structure, ES), the Economic Activity factor (EA) and Population (P), respectively. Data came from the World Input–Output Database (WIOD) and determined the period under consideration. The paper focuses on the 35 productive sectors included in the WIOD. Major findings show that RES acted in detriment to the drivers of CO2 emissions. This may be stated for the last few years under consideration. The positive trend for the share of RES in Spain׳s energy matrix, together with the negative tendency in the use of fossil fuels, leads us to be optimistic.

Biological roles of fungal carotenoids.

Abstract: Carotenoids are terpenoid pigments widespread in nature, produced by bacteria, fungi, algae and plants. They are also found in animals, which usually obtain them through the diet. Carotenoids in plants provide striking yellow, orange or red colors to fruits and flowers, and play important metabolic and physiological functions, especially relevant in photosynthesis. Their functions are less clear in non-photosynthetic microorganisms. Different fungi produce diverse carotenoids, but the mutants unable to produce them do not exhibit phenotypic alterations in the laboratory, apart of lack of pigmentation. This review summarizes the current knowledge on the functional basis for carotenoid production in fungi. Different lines of evidence support a protective role of carotenoids against oxidative stress and exposure to visible light or UV irradiation. In addition, the carotenoids are intermediary products in the biosynthesis of physiologically active apocarotenoids or derived compounds. This is the case of retinal, obtained from the symmetrical oxidative cleavage of β-carotene. Retinal is the light-absorbing prosthetic group of the rhodopsins, membrane-bound photoreceptors present also in many fungal species. In Mucorales, β-carotene is an intermediary in the synthesis of trisporoids, apocarotenoid derivatives that include the sexual hormones the trisporic acids, and they are also presumably used in the synthesis of sporopollenin polymers. In conclusion, fungi have adapted their ability to produce carotenoids for different non-essential functions, related with stress tolerance or with the synthesis of physiologically active by-products.

New Evidence on Breastfeeding and Postpartum Depression: The Importance of Understanding Women's Intentions

Abstract: This study aimed to identify the causal effect of breastfeeding on postpartum depression (PPD), using data on mothers from a British survey, the Avon Longitudinal Study of Parents and Children. Multivariate linear and logistic regressions were performed to investigate the effects of breastfeeding on mothers’ mental health measured at 8 weeks, 8, 21 and 32 months postpartum. The estimated effect of breastfeeding on PPD differed according to whether women had planned to breastfeed their babies, and by whether they had shown signs of depression during pregnancy. For mothers who were not depressed during pregnancy, the lowest risk of PPD was found among women who had planned to breastfeed, and who had actually breastfed their babies, while the highest risk was found among women who had planned to breastfeed and had not gone on to breastfeed. We conclude that the effect of breastfeeding on maternal depression is extremely heterogeneous, being mediated both by breastfeeding intentions during pregnancy and by mothers’ mental health during pregnancy. Our results underline the importance of providing expert breastfeeding support to women who want to breastfeed; but also, of providing compassionate support for women who had intended to breastfeed, but who find themselves unable to.

Antecedents and Dimensions of Supply Chain Robustness: A Systematic Literature Review

Abstract: Purpose – The purpose of this paper is to provide groundwork for an emerging theory of supply chain robustness – which has been conceptualized as a dimension of supply chain resilience – through reviewing and synthesizing related yet disconnected studies. The paper develops a formal definition of supply chain robustness to build a framework that captures the dimensions, antecedents and moderators of the construct as discussed in the literature. Design/methodology/approach – The authors apply a systematic literature review approach. In order to reduce researcher bias, they involve a team of academics, librarians and managers. Findings – The paper first, provides a formal definition of supply chain robustness; second, builds a theoretical framework of supply chain robustness that augments both causal and descriptive knowledge; third,shows how findings in this review support practice; and fourth,reveals methodological insights on the use of journal rankings in reviews. Research limitations/implications – At ...

Low Pressure CO2 Hydrogenation to Methanol over Gold Nanoparticles Activated on a CeOx/TiO2 Interface

Abstract: Capture and recycling of CO2 into valuable chemicals such as alcohols could help mitigate its emissions into the atmosphere. Due to its inert nature, the activation of CO2 is a critical step in improving the overall reaction kinetics during its chemical conversion. Although pure gold is an inert noble metal and cannot catalyze hydrogenation reactions, it can be activated when deposited as nanoparticles on the appropriate oxide support. In this combined experimental and theoretical study, it is shown that an electronic polarization at the metal-oxide interface of Au nanoparticles anchored and stabilized on a CeO(x)/TiO2 substrate generates active centers for CO2 adsorption and its low pressure hydrogenation, leading to a higher selectivity toward methanol. This study illustrates the importance of localized electronic properties and structure in catalysis for achieving higher alcohol selectivity from CO2 hydrogenation.

Bioactive Compounds Isolated from Microalgae in Chronic Inflammation and Cancer.

Abstract: The risk of onset of cancer is influenced by poorly controlled chronic inflammatory processes. Inflammatory diseases related to cancer development include inflammatory bowel disease, which can lead to colon cancer, or actinic keratosis, associated with chronic exposure to ultraviolet light, which can progress to squamous cell carcinoma. Chronic inflammatory states expose these patients to a number of signals with tumorigenic effects, including nuclear factor kappa B (NF-κB) and mitogen-activated protein kinases (MAPK) activation, pro-inflammatory cytokines and prostaglandins release and ROS production. In addition, the participation of inflammasomes, autophagy and sirtuins has been demonstrated in pathological processes such as inflammation and cancer. Chemoprevention consists in the use of drugs, vitamins, or nutritional supplements to reduce the risk of developing or having a recurrence of cancer. Numerous in vitro and animal studies have established the potential colon and skin cancer chemopreventive properties of substances from marine environment, including microalgae species and their products (carotenoids, fatty acids, glycolipids, polysaccharides and proteins). This review summarizes the main mechanisms of actions of these compounds in the chemoprevention of these cancers. These actions include suppression of cell proliferation, induction of apoptosis, stimulation of antimetastatic and antiangiogenic responses and increased antioxidant and anti-inflammatory activity.

Endodontic medicine: connections between apical periodontitis and systemic diseases.

Abstract: The prevalence of apical periodontitis (AP) in Europe has been reported to affect 61% of individuals and 14% of teeth, and increase with age. Likewise, the prevalence of root canal treatment (RCT) in Europe is estimated to be around 30-50% of individuals and 2-9% of teeth with radiographic evidence of chronic persistent AP in 30-65% of root filled teeth (RFT). AP is not only a local phenomenon and for some time the medical and dental scientific community have analysed the possible connection between apical periodontits and systemic health. Endodontic medicine has developed, with increasing numbers of reports describing the association between periapical inflammation and systemic diseases. The results of studies carried out both in animal models and humans are not conclusive, but suggest an association between endodontic variables, that is AP and RCT, and diabetes mellitus (DM), tobacco smoking, coronary heart disease and other systemic diseases. Several studies have reported a higher prevalence of periapical lesions, delayed periapical repair, greater size of osteolityc lesions, greater likelihood of asymptomatic infections and poorer prognosis for RFT in diabetic patients. On the other hand, recent studies have found that a poorer periapical status correlates with higher HbA1c levels and poor glycaemic control in type 2 diabetic patients. However, there is no scientific evidence supporting a causal effect of periapical inflammation on diabetes metabolic control. The possible association between smoking habits and endodontic infection has also been investigated, with controversial results. The aim of this paper was to review the literature on the association between endodontic variables and systemic health (especially DM and smoking habits).

A bounded-search iterated greedy algorithm for the distributed permutation flowshop scheduling problem

Abstract: As the interest of practitioners and researchers in scheduling in a multi-factory environment is growing, there is an increasing need to provide efficient algorithms for this type of decision problems, characterised by simultaneously addressing the assignment of jobs to different factories/workshops and their subsequent scheduling. Here we address the so-called distributed permutation flowshop scheduling problem, in which a set of jobs has to be scheduled over a number of identical factories, each one with its machines arranged as a flowshop. Several heuristics have been designed for this problem, although there is no direct comparison among them. In this paper, we propose a new heuristic which exploits the specific structure of the problem. The computational experience carried out on a well-known testbed shows that the proposed heuristic outperforms existing state-of-the-art heuristics, being able to obtain better upper bounds for more than one quarter of the problems in the testbed.