59 research outputs found

    A risk-based methodology for defining the time of intentional controlled islanding

    Get PDF
    This paper has been accepted for presentation at the IEEE/PES ISGT LA 2015, for publication in the conference proceedings and submitted for publication in the IEEE Xplore.Power systems are operated close to their stability limits and this increases the probability of cascading outages leading to large-area blackouts. To mitigate these phenomena, intentional controlled islanding (ICI) has been suggested as an effective corrective strategy that splits the system into sustainable subsystems (islands). There are two primary aspects associated with ICI: i) where to island, and ii) when to island? This work focuses on the latter and proposes a risk-based methodology that compares in a real-time fashion (i.e., quickly enough) the overall risk of the system without and with islanding (i.e., when an ICI scheme is activated) in order to define a suitable time for system splitting. Simulation results on the IEEE 9-bus system demonstrate the effectiveness of the methodology in determining a suitable time for the creation of islands, which in turn corresponds to the crossing point between the risks of the system without and with islanding.Universidad de Costa Rica. Escuela de Ingeniería EléctricaUCR::Vicerrectoría de Docencia::Ingeniería::Facultad de Ingeniería::Escuela de Ingeniería Eléctric

    Closed genome and comparative phylogenetic analysis of the clinical multidrug resistant Shigella sonnei strain 866

    Get PDF
    Shigella sonneiis responsible for the majority of shigellosis infections in the US with over 500,000 cases reported annually. Here, wepresent the complete genome of the clinical multidrug resistant (MDR) strain 866, which is highly susceptible to bacteriophageinfections. The strain has a circular chromosome of 4.85 Mb and carries a 113 kb MDR plasmid. This IncB/O/K/Z-type plasmid, termedp866, confers resistance to five different classes of antibiotics including ß-lactamase, sulfonamide, tetracycline, aminoglycoside, andtrimethoprim. Comparative analysis of the plasmid architecture and gene inventory revealed that p866 shares its plasmid backbonewith previously described IncB/O/K/Z-typeShigellaspp. andEscherichiacoliplasmids, but is differentiated by the insertion of antibioticresistance cassettes, which we found associated with mobile genetic elements such as Tn3, Tn7, and Tn10. A whole genome-derivedphylogenetic reconstruction showed the evolutionary relationships ofS. sonneistrain 866 and the four establishedShigellaspecies,highlighting the clonal nature ofS. sonnei

    Investigation on the evolution of Shiga Toxin-converting phages based on whole genome sequencing

    Get PDF
    Bacteriophages are pivotal elements in the dissemination of virulence genes. The main virulence determinants of Shiga Toxin producing E. coli, Shiga Toxins (Stx), are encoded by genes localized in the genome of lambdoid bacteriophages. Stx comprise two antigenically different types, Stx1 and Stx2, further divided into subtypes. Among these, certain Stx2 subtypes appear to be more commonly occurring in the most severe forms of the STEC disease, haemorrhagic colitis and haemolytic uremic syndrome (HUS). This study aimed at obtaining insights on the evolution of Stx2 bacteriophages, due to their relevance in public health, and we report here on the analysis of the genomic structure of Stx2 converting phages in relation with the known reservoir of the E. coli strains harboring them. Stx2-converting phages conveying the genes encoding different stx2 subtypes have been isolated from STEC strains and their whole genomes have been sequenced, analyzed and compared to those of other Stx2 phages available in the public domain. The phages' regions containing the stx2 genes have been analyzed in depth allowing to make inference on the possible mechanisms of selection and maintenance of certain Stx2 phages in the reservoir. The 'stx regions' of different stx2 gene subtypes grouped into three different evolutionary lines in the comparative analysis, reflecting the frequency with which these subtypes are found in different animal niches, suggesting that the colonization of specific reservoir by STEC strains could be influenced by the Stx phage that they carry. Noteworthy, we could identify the presence of nanS-p gene exclusively in the 'stx regions' of the phages identified in STEC strains commonly found in cattle. As a matter of fact, this gene encodes an esterase capable of metabolizing sialic acids produced by submaxillary glands of bovines and present in great quantities in their gastrointestinal tract

    Tracking bacterial virulence: global modulators as indicators

    Get PDF
    The genomes of Gram-negative bacteria encode paralogues and/or orthologues of global modulators. The nucleoid-associated H-NS and Hha proteins are an example: several enterobacteria such as Escherichia coli or Salmonella harbor H-NS, Hha and their corresponding paralogues, StpA and YdgT proteins, respectively. Remarkably, the genome of the pathogenic enteroaggregative E. coli strain 042 encodes, in addition to the hha and ydgT genes, two additional hha paralogues, hha2 and hha3. We show in this report that there exists a strong correlation between the presence of these paralogues and the virulence phenotype of several E. coli strains. hha2 and hha3 predominate in some groups of intestinal pathogenic E. coli strains (enteroaggregative and shiga toxin-producing isolates), as well as in the widely distributed extraintestinal ST131 isolates. Because of the relationship between the presence of hha2/hha3 and some virulence factors, we have been able to provide evidence for Hha2/Hha3 modulating the expression of the antigen 43 pathogenic determinants. We show that tracking global modulators or their paralogues/orthologues can be a new strategy to identify bacterial pathogenic clones and propose PCR amplification of hha2 and hha3 as a virulence indicator in environmental and clinical E. coli isolates

    Prevalence and distribution of infectious and parasitic agents in roe deer from Spain and their possible role as reservoirs

    Get PDF
    In order to provide up-to-date information about the prevalence of infectious and parasitic agents in Spanish roe deer (Capreolus capreolus), samples from 93 animals hunted from January 2013 to April 2015 were collected and analysed by parasitological, serological and molecular techniques. Sampled animals came from four roe deer populations corresponding to Oceanic, Continental, Mediterranean and Mountainous ecosystems of Spain. Data regarding sex, age and year were also considered. A high percentage of roe deer (95.7%) resulted positive for at least one agent. Sarcocystis spp. was the most frequently diagnosed genus (88.8%), followed by gastrointestinal nematodes (62.9%) and Schmallenberg virus (53.5%). Varestrongylus capreoli (38%), Anaplasma phagocitophylum (34.2%), Eimeria spp. (29.2%), Toxoplasma gondii (25%) and Cephenemyia stimulator (23.8%) displayed medium prevalences and, finally low percentages were registered for Moniezia spp. (6.7%), Dictyocaulus noerneri (2.4%) and Mycobacterium avium subsp. paratuberculosis (1.5%). No infections by Neospora caninum, Bovine herpesvirus, pestivirus or Coxiella burnetii were found. Climate was significantly associated with the prevalence of T. gondii, C. stimulator and A. phagocitophylum, with higher prevalences in animals from Oceanic and Mediterranean areas. Our results suggest that infections affecting Spanish roe deer, especially those of parasitic aetiology, represent one of the causes of the descent in the abundance of this ungulate in the last years. Moreover, the high prevalence of zoonotic agents such as T. gondii and A. phagocitophylum could also have a great relevance in the environmental and/or Public Health.This research was supported by a Programme for consolidating and structuring competitive research groups (GRC2015/003, Xunta de Galicia) and by the Research Project ‘RUMIGAL: Rede de estudo multidisciplinar dos ruminantes en Galicia’ (R2014/005, Xunta de Galicia, Spain)S

    Robots miniaturizados: diseño, implementación y aplicaciones

    Get PDF
    Proyecto de Investigación (Código: 5402-1360-2401 FI-298-09) Instituto Tecnológico de Costa Rica. Escuela de Ingeniería Electrónica, Escuela de Física, Escuela de Ingeniería en Computación, 2014Este informe presenta los resultados obtenidos en el proyecto “Robots miniaturizados: diseño, implementación y aplicaciones”, con número de proyecto 5402-1360-2401. Se presentan los resultados obtenidos con respecto a locomoción autónoma, comunicación inalámbrica óptica y alimentación inalámbrica, actuadores para manipulación y microcorte e interfaz con una PC para datos y comandos. El minirobot fue diseñado para operar en un área de al menos 30cm de diámetro y tiene un tamaño de 2.3 cm x 2.6 cm x 1.78 cm. Para el estudio de los actuadores del minirobot se utilizó simulación multifísica por el método de elementos finitos con el software COMSOL Multiphysics. La estructura del informe es la siguiente: en la sección de Introducción se tratan los antecedentes, la descripción del problema a resolver, así como los objetivos planteados en el proyecto de investigación. En la sección de metodología se resume el método de investigación y los flujos de diseño. En la sección de resultados se presentan los resultados obtenidos correspondientes a: comunicación inlámbrica óptica, sistema de locomoción, interfaz humano-máquina y software, alimentación inalámbrica de energia y actuadores. Posteriormente, se discuten los resultados obtenidos junto con las principales conclusiones del proyecto y las recomendaciones para su continuación y/o aprovechamiento de los resultados.Instituto Tecnológico de Costa Rica. Escuela de Ingeniería Electrónica. Escuela de Física. Escuela de Ingeniería en Computación

    Greenhouse gases emissions from the diet and risk of death and chronic diseases in the EPIC-Spain cohort

    Get PDF
    The Author(s) 2020.[Background]: Evidence from the scientific literature shows a significant variation in greenhouse gas (GHG) emissions from the diet, according to the type of food consumed. We aim to analyze the relationship between the daily dietary GHG emissions according to red meat, fruit and vegetables consumption and their relationship with risk of total mortality, and incident risk of chronic diseases. [Methods]: We examined data on the EPIC-Spain prospective study, with a sample of 40 621 participants. Dietary GHG emission values were calculated for 57 food items of the EPIC study using mean emission data from a systematic review of 369 published studies. [Results]: Dietary GHG emissions (kgCO2eq/day), per 2000 kcal, were 4.7 times higher in those with high red-meat consumption (>140 g/day) than those with low consumption (<70 g/day). The average dietary GHG emissions were similar in males and females, but it was significantly higher in youngest people and in those individuals with lower educational level, as well as for northern EPIC centers of Spain. We found a significant association with the risk of mortality comparing the third vs. the first tertile of dietary GHG emissions [hazard ratio (HR) 1.095; 95% confidence interval (CI) 1.007–1.19; trend test 0.037]. Risk of coronary heart disease (HR 1.26; 95% CI 1.08–1.48; trend test 0.003) and risk of type 2 diabetes (HR 1.24; 95% CI 1.11–1.38; trend test 0.002) showed significant association as well. [Conclusions]: Decreasing red-meat consumption would lead to reduce GHG emissions from diet and would reduce risk of mortality, coronary heart disease and type 2 diabetes.Peer reviewe

    Novedades corológicas y nomenclaturales para la flora vascular de la Sierra de Gredos (Sistema Central), III

    Get PDF
    In the present paper we present the floristic novelties for the flora of the Sierra de Gredos resulting from the explorations of these mountains and that, mostly, are the result of the field trips of the year 2021. We present 31 chorological novelties, among which we highlight the finding in the Community of Madrid of the restricted endemic Iberodes brassicifolia (Lag.) M. Serrano, R. Carbajal & S. Ortiz. Also relevant are Herniaria hirsuta L., Rosa glauca Pourr. (new for the Spanish Central System) and Rosa coriifolia Fr. (new for Extremadura and the whole of the Sierra de Gredos), as well as Soliva sessilisRuiz & Pav., Trifolium vesiculosumSavi (new for Castilla y León) and Lepidium villarsii Gren. & Godr. subsp. villarsii (new for the Sierra de Gredos). Finally, two new nomenclatural combinations are made in the genus Tephroseris (Rchb.) Rchb.: Tephroseris balbisiana (DC.) Holub subsp. coincy (Rouy) P. Vargas & Luceño, endemic to Gredos range, and Tephroseris balbisiana subsp. elodes (Boiss. ex DC.) P. Vargas & Luceño, endemic to Sierra Nevada
    corecore