1,495 research outputs found

    Analysis of a class of boundary value problems depending on left and right Caputo fractional derivatives

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    In this work we study boundary value problems associated to a nonlinear fractional ordinary differential equation involving left and right Caputo derivatives. We discuss the regularity of the solutions of such problems and, in particular, give precise necessary conditions so that the solutions are C1([0, 1]). Taking into account our analytical results, we address the numerical solution of those problems by the augmented-RBF method. Several examples illustrate the good performance of the numerical method.P.A. is partially supported by FCT, Portugal, through the program ‚ÄúInvestigador FCT‚ÄĚ with reference IF/00177/2013 and the scientific projects PEstOE/MAT/UI0208/2013 and PTDC/MAT-CAL/4334/2014. R.F. was supported by the ‚ÄúFunda√ß√£o para a Ci√™ncia e a Tecnologia (FCT)‚ÄĚ through the program ‚ÄúInvestigador FCT‚ÄĚ with reference IF/01345/2014.info:eu-repo/semantics/publishedVersio

    Anomaly detection in Multivariate Temporal Data for Vessels Abnormal Behaviour Detection

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    The growing number of deployed data mining systems leverage the interest in temporal data anomaly detection. From cyber-security or finance to heart-diseases detection, unexpected data often incorporate critical information that must be analysed. Data anomalies have long been studied from an univariate perspective where only one data dimension changes over time. Few works have been dedicated to multivariate anomaly detection. In this work we provide a comprehensive and structured analysis of the main definitions, state-of-art methods and approaches focusing multivariate temporal data anomaly detection. Our research focus on dealing with variable length data series with millions of samples and multiple feature categories, either static or dynamic, real or categorical valued. We describe a case-study in the maritime domain investigating the unusual spatio-temporal behaviour of commercial vessels and experiment over two open datasets and one got from the MARISA H2020 Project1

    Portuguese capital in the XXIst century: a tale of misallocation?

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    We analyze the patterns of productivity in the Portuguese manufacturing sectorfrom 2006 to 2017. With a more comprehensive firm-level dataset and with a largertime-span, we confirm the findings of Gopinath et al. (2017): there is evidence ofincreased capital misallocation. However, we show that the results hinge criticallyon the capital stock measure used. Relying on an improved measure, we find twokey results, contradicting the initial ones: (i) a declining economic potential of themanufacturing firms, measured by an hypothetical efficient-level TFP, likely driven bythe destruction of productive capital during the period; and (ii) a reduction in capitalmisallocation, as actual TFP declined less than the theoretical one.Keyword

    Bio-Inspired Virtual Populations: Adaptive Behavior with Affective Feedback

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    In this paper, we describe an agency model for generative populations of humanoid characters, based upon temporal variation of affective states. We have built on an existing agent framework from Sequeira et al. [17], and adapted it to be susceptible to temperamental and emotive states in the context of cooperative and non-cooperative interactions based on trading activity. More specifically, this model operates within two existing frameworks: a) intrinsically motivated reinforcement learning, structured upon affective appraisals in the relationship of the agents with their environment [19,17]; b) a multi-temporal representation of individual psychology, common in the field of affective computing, structuring individual psychology as a tripartite relationship: emotions-moods-personality [7,15]. Results show a populations of agents that express their individuality and autonomy with a high level of heterogeneous and spontaneous behaviors, while simultaneously adapting and overcoming their perceptual limitations

    Understanding Mexican and Brazilian multilatinas market selection

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    Mexican and Brazilian Multilatinas have become a phenomenon that has caught the attention of many authors and researchers around the world. This Master’s Final Thesis on Multilatinas was developed to understand Mexican and Brazilian Multilatinas’ market selection and why these companies first expand to geographically close countries. The CAGE framework developed by Ghemawat (2001) measures the distance between two countries according to Cultural, Administrative, Geographic and Economic criteria and was the main indicator for this research. The literature review allowed for the exploration of concepts related to a Multilatina’s expansion, such as internationalization, market selection, emerging market multinational companies, and Multilatinas and the CAGE framework. The Uppsala and network models studied in the literature explained how managers decide on market selection and which factors contribute to it. The development of a conceptual framework related to how Mexican and Brazilian Multilatinas select their markets, in a systematic or opportunistic way, and how CAGE factors influence managers’ decisions. It was possible to verify that countries where Mexican and Brazilian Multilatinas expand are the ones with the lowest CAGE distance, so these factors influence market selection for Mexican and Brazilian Multilatinas

    Virulence of Salmonella typhimurium 1,4,[5],12:i:- : the new emergent strain

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    Tese de Doutoramento em Ci√™ncias Veterin√°rias na Especialidade Sanidade AnimalSalmonella serovar 1,4,[5],12:i:- is presently considered one of the major serovars responsible for human salmonellosis worldwide. A multidisciplinary approach, including the fields of epidemiology, spatial statistics, clinical and applied microbiology was used to perform an extensive characterization of Salmonella 1,4,[5],12:i:- isolates obtained by the National Health Institute Dr. Ricardo Jorge, which was lacking due to the recent emergence. It was observed that cases are reported in most districts, being more frequent in the Portuguese coastland. Spatial statistical analysis showed a significant geographic clustering, pointing out for the importance of evaluating these areas to identify risk factors, in order to establish adequate prevention programs. The most relevant antimicrobial profile in this serovar is the tetra-resistance pattern (R-type ASSuT), displaying resistance to ampicillin, streptomycin, sulphonamides and tetracyclines. A high occurrence of R-type ASSuT isolates was observed in the isolates under study, with the majority harboring the resistance genes frequently associated with the European clone, namely blaTEM, sul2, straA-straB, tetB. Additionally, resistance to quinolones and 3rd generation cephalosporin was also detected. In Portugal, the rapid spread of Salmonella 1,4,[5],12:i:- R-type ASSuT might be related with the diversity of pulsotypes and also the presence of a core of virulence factors, including biofilm production. Biofilm-forming ability varied between sample locations and collection year, and can be one of the virulence features related with the rise of this serovar. Furthermore, biofilm formation was evaluated in vitro using a simulated human intestinal environment. In such conditions was observed an impairment of biofilm production, revealing that conditions mimicking the human intestinal tract can influence the biofilm-forming ability of the isolates under study. This research highlight the critical importance of close surveillance of Salmonella 1,4,[5],12:i:- in Portugal, including R-type ASSuT isolates. Information gathered may unravel Salmonella 1,4,[5],12:i:- features, prevent the dissemination to other regions and also benefit the medical community in order to rationalize salmonellosis antimicrobial therapeutics.RESUMO - Virul√™ncia de Salmonella Typhimurium 1,4,[5],12:i:-, a nova estirpe pand√©mica* - Salmonella √© uma bact√©ria Gram-negativa pertencente √† fam√≠lia Enterobacteriaceae, sendo uma das principais respons√°veis pela morbilidade e mortalidade associadas a toxinfec√ß√Ķes alimentares. Pode manifestar-se num espectro de sintomatologia variado, incluindo a gastroenterite, a bacteri√©mia e a infec√ß√£o focal. Este g√©nero inclu√≠ mais de 2600 serovares descritos, distribu√≠dos por apenas duas esp√©cies: Salmonella enterica que inclui todos os serovares patog√©nicos para os humanos e Salmonella bongori. Actualmente, um dos principais serovares respons√°veis pela salmonelose humana em todo o mundo √© o 1,4,[5],12:i:-. Este serovar √© uma variante monof√°sica de Salmonella Typhimurium, muito semelhante a n√≠vel molecular, sendo caracterizado pela aus√™ncia da express√£o do gene fljB. Devido √† sua recente emerg√™ncia, estudos que avaliem este serovar s√£o escassos, particularmente em Portugal, o que definiu o √Ęmbito desta investiga√ß√£o, que teve como objectivo a caracteriza√ß√£o epidemiol√≥gica e microbiol√≥gica, tanto do ponto de vista fenot√≠pico e genot√≠pico, de isolados de Salmonella 1,4,[5],12:i:- obtidos em Portugal a partir de diferentes origens, incluindo amostras humanas, animais e ambientais. Numa primeira fase foi realizada uma caracteriza√ß√£o demogr√°fica, epidemiol√≥gica e espacial de todos os casos de Salmonelose 1,4,[5],12:i:- humana notificados em Portugal pelo Instituto Nacional de Sa√ļde Dr. Ricardo Jorge (INSA), durante um per√≠odo de 10 anos, desde 2001 a 2011. Foram recolhidos dados sobre a origem, ano e m√™s de amostragem, g√©nero, idade, distrito e munic√≠pio de resid√™ncia dos pacientes. Foi realizada a an√°lise estat√≠stica descritiva, bem como, a an√°lise estat√≠stica espacial atrav√©s do software SaTScan‚ĄĘ, combinada com an√°lise atrav√©s de software de georeferencia√ß√£o, o QGIS‚ĄĘ, de forma a caracterizar a epidemiologia e identificar agrupamentos espaciais de risco superior de infec√ß√£o por Salmonella 1,4,[5],12:i:- em Portugal. Globalmente, observou-se que em Portugal, a maioria dos distritos tem casos notificados de infec√ß√£o por Salmonella 1,4,[5],12:i:-. Verificou-se tamb√©m um aumento da incid√™ncia durante o intervalo de 2004 a 2011, com um maior n√ļmero de casos na regi√£o litoral do pa√≠s, incluindo distritos como Porto, Lisboa e Aveiro, o que pode ser explicado pela maior densidade populacional nestas √°reas. A maioria das infec√ß√Ķes ocorreu durante Maio e Outubro, e o menor n√ļmero em Fevereiro, afectando principalmente indiv√≠duos jovens.[...]*O autor escreve segundo o antigo Acordo Ortogr√°ficoThis work was supported by National Health Institute Doutor Ricardo Jorge (INSA) and funded by Centre for Interdisciplinary Research in Animal Health (CIISA)N/

    Phenotypic and genotypic characterization of virulence traits of staphylococci from animal origin

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    Disserta√ß√£o de Mestrado Integrado em Medicina Veterin√°riaStaphylococci can express a wide array of virulence traits which may strongly influence the infection prognosis, often being a multidrug resistant animal pathogen, responsible for conditions such as abscesses, dermatitis or mastitis. In this study we aimed to perform a phenotypic and genotypic characterization of virulence traits of methicillin-resistant staphylococci (MRS) isolates of animal origin. A total of 253 staphylococci were evaluated for methicillin resistance. This collection comprises isolates from bovine clinical and subclinical mastitis and other clinical isolates from dogs, cats, horses and goats. Identification had been previously performed by biochemical tests and confirmed to genus or species level by PCR and isolates clonality was evaluated by PFGE. Methicillin resistance screening was performed by the oxacillin disc diffusion according to CLSI guidelines and confirmed using a MRSA modified medium and by PCR amplification of the mecA gene. The occurrence of the new mecA homolog, LGA251 was evaluated by PCR in mecA negative MRS isolates. Virulence traits of MRS such as coagulase, haemolysins, DNase, gelatinase and lipase were phenotypically evaluated. Biofilm production was also phenotypically evaluated and by PCR of icaA, icaD and bap genes. Quorum-sensing system agr was determined by PCR. Antimicrobial susceptibility to 18 compounds was evaluated according to CLSI guidelines. The presence of bacteriophages and the production of bacteriocins were determined by plaque assays. A total of 26 isolates were identified as MRS: S. epidermidis (n=16), S. aureus (n=4) and Staphylococcus spp. (n=6). From the 26 MRS detected, 19.2% were coagulase-positive, 73.1% produced haemolysins, 26.9% produced DNase, 96.2% were gelatinase-positive, 69.2% were lipase-positive and 38.5% of the isolates were able to express biofilm in vitro. IcaA and icaD genes were both present in 38.5% of the isolates, but none was bap-positive. Only 11.5% of the isolates were typeable for agr. Antimicrobial co-resistance ranged from 0% (Chloramphenicol, Vancomycin) to 92.3% (Nalidixic acid). Bacteriophages were present in 34.6% of the isolates and none produced bacteriocins. The high frequencies of virulence traits present combined with the high antimicrobial coresistance profiles observed, suggest that these isolates may represent a serious problem with major public health implications, re-enforcing the importance of the wide concept of ‚ÄúOne Health‚ÄĚ.RESUMO - Caracteriza√ß√£o fenot√≠pica e genot√≠pica de factores de virul√™ncia de staphylococci de origem animal - As bact√©rias pertencentes ao g√©nero Staphylococcus podem expressar uma ampla gama de factores de virul√™ncia que influenciam o progn√≥stico de uma infec√ß√£o. Podem ser agentes patog√©nicos multirresistentes em animais, respons√°veis por doen√ßas como abcessos, dermatites ou mastites. Neste estudo realizou-se uma caracteriza√ß√£o fenot√≠pica e genot√≠pica dos factores de virul√™ncia de staphylococci resistentes √† meticilina (MRS) de origem animal. Um total de 253 staphylococci foram avaliados para resist√™ncia √† meticilina. Esta colec√ß√£o inclui isolados de mastites cl√≠nicas e subcl√≠nicas bovinas e isolados cl√≠nicos de c√£es, gatos, cavalos e cabras. A identifica√ß√£o dos isolados tinha sido previamente realizada por testes bioqu√≠micos e foi confirmada ao g√©nero ou esp√©cie por PCR e a clonalidade dos isolados foi avaliada por PFGE. A resist√™ncia √† meticilina foi avaliada pelo m√©todo de difus√£o em disco com oxacilina de acordo com as normas do CLSI e confirmada pelo meio MRSA modificado e por PCR do gene mecA. A ocorr√™ncia do novo hom√≥logo mecA, LGA251 foi avaliada por PCR em MRS mecA negativos. A presen√ßa de factores de virul√™ncia como coagulase, hemolisinas, DNase, gelatinase e lipase foi avaliada fenotipicamente. A produ√ß√£o de biofilme foi tamb√©m avaliada fenotipicamente e por PCR dos genes icaA, icaD and bap. O sistema de quorum-sensing agr foi avaliado por PCR. A susceptibilidade a 18 antimicrobianos foi determinada de acordo com as normas do CLSI. A presen√ßa de bacteri√≥fagos e a produ√ß√£o de bacteriocinas foram avaliadas por ensaios em placa. Um total de 26 isolados foram identificados como MRS: S. epidermidis (n=16), S. aureus (n=4) e Staphylococcus spp. (n=6). Dos 26 MRS, 19,2% eram coagulase-positivos, 73,1% produziram hem√≥lise, 26,9% produziram DNase, 96,2% foram gelatinase-positivos, 69,2% foram lipase-positivos e 38,5% dos isolados foram capazes de expressar biofilme in vitro. Os genes icaA e icaD est√£o presentes em 38,5% dos isolados, mas nenhum foi bap-positivo. Apenas 11,5% dos isolados foram tipificados para com o sistema agr. A co-resist√™ncia a agentes antimicrobianos variou de 0% (cloranfenicol e vancomicina) at√© 92,3% (√°cido nalid√≠xico). Os bacteri√≥fagos estavam presentes em 34,6% dos isolados e nenhum produziu bacteriocinas. As elevadas frequ√™ncias de factores de virul√™ncia combinadas com os elevados perfis de coresist√™ncia a antimicrobianos sugerem que estes isolados podem representar um problema s√©rio para sa√ļde p√ļblica, refor√ßando a import√Ęncia do conceito de "Uma s√≥ sa√ļde"

    Scalable semantic aware context storage

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    In recent years the Internet has grown by incorporating billions of small devices, collecting real-world information and distributing it though various systems. As the number of such devices grows, it becomes increasingly difficult to manage all these new information sources. Several context representation schemes have tried to standardize this information, however none of them have been widely adopted. Instead of proposing yet another context representation scheme, we discuss an efficient way to deal with this diversity of representation schemes. We define the basic requirements for context storage systems, analyse context organizations models and propose a new context storage solution. Our solution implements an organizational model that improves scalability, semantic extraction and minimizes semantic ambiguity
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