978 resultados para CORRELATIONS
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Every year forest fires consume large areas, being a major concern in many countries like Australia, United States and Mediterranean Basin European Countries (e.g., Portugal, Spain, Italy and Greece). Understanding patterns of such events, in terms of size and spatiotemporal distributions, may help to take measures beforehand in view of possible hazards and decide strategies of fire prevention, detection and suppression. Traditional statistical tools have been used to study forest fires. Nevertheless, those tools might not be able to capture the main features of fires complex dynamics and to model fire behaviour [1]. Forest fires size-frequency distributions unveil long range correlations and long memory characteristics, which are typical of fractional order systems [2]. Those complex correlations are characterized by self-similarity and absence of characteristic length-scale, meaning that forest fires exhibit power-law (PL) behaviour. Forest fires have also been proved to exhibit time-clustering phenomena, with timescales of the order of few days [3]. In this paper, we study forest fires in the perspective of dynamical systems and fractional calculus (FC). Public domain forest fires catalogues, containing data of events occurred in Portugal, in the period 1980 up to 2011, are considered. The data is analysed in an annual basis, modelling the occurrences as sequences of Dirac impulses. The frequency spectra of such signals are determined using Fourier transforms, and approximated through PL trendlines. The PL parameters are then used to unveil the fractional-order dynamics characteristics of the data. To complement the analysis, correlation indices are used to compare and find possible relationships among the data. It is shown that the used approach can be useful to expose hidden patterns not captured by traditional tools.
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Abstract: Preferential flow and transport through macropores affect plant water use efficiency and enhance leaching of agrochemicals and the transport of colloids, thereby increasing the risk for contamination of groundwater resources. The effects of soil compaction, expressed in terms of bulk density (BD), and organic carbon (OC) content on preferential flow and transport were investigated using 150 undisturbed soil cores sampled from 15 × 15–m grids on two field sites. Both fields had loamy textures, but one site had significantly higher OC content. Leaching experiments were conducted in each core by applying a constant irrigation rate of 10 mm h−1 with a pulse application of tritium tracer. Five percent tritium mass arrival times and apparent dispersivities were derived from each of the tracer breakthrough curves and correlated with texture, OC content, and BD to assess the spatial distribution of preferential flow and transport across the investigated fields. Soils from both fields showed strong positive correlations between BD and preferential flow. Interestingly, the relationships between BD and tracer transport characteristics were markedly different for the two fields, although the relationship between BD and macroporosity was nearly identical. The difference was likely caused by the higher contents of fines and OC at one of the fields leading to stronger aggregation, smaller matrix permeability, and a more pronounced pipe-like pore system with well-aligned macropores.
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Eight tropical fruit pulps from Brazil were simultaneously characterised in terms of their antioxidant and antimicrobial properties. Antioxidant activity was screened by DPPH radical scavenging activity (126–3987 mg TE/100 g DW) and ferric reduction activity power (368–20819 mg AAE/100 g DW), and complemented with total phenolic content (329–12466 mg GAE/100 g DW) and total flavonoid content measurements (46–672 mg EE /100 g DW), whereas antimicrobial activity was tested against the most frequently found food pathogens. Acerola and açaí presented the highest values for the antioxidant-related measurements. Direct correlations between these measurements could be observed for some of the fruits. Tamarind exhibited the broadest antimicrobial potential, having revealed growth inhibition of Pseudomonas aeruginosa. Escherichia coli, Listeria monocytogenes, Salmonella sp. and Staphylococcus aureus. Açaí and tamarind extracts presented an inverse relationship between antibacterial and antioxidant activities, and therefore, the antibacterial activity cannot be attributed (only) to phenolic compounds.
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Purpose: The studies on links between sustainability, innovation, and competitiveness have been mainly focused at organizational and business level. The purpose of this research is to investigate if there is a correlation between these three variables at country level. Using international well recognized rankings of countries sustainability, innovation, and competitiveness, correlation analysis was performed allowing for the conclusion that there are indeed high correlations (and possible relationships) between the three variables at country level. Design/methodology/approach: Sustainability, innovation, and competitiveness literature were reviewed identifying a lack of studies examining these three variables at country level. Three major well recognized indexes were used to support the quantitative research: The World Economic Forum (2013) Sustainability-adjusted global competitiveness index, the Global Innovation Index (2014) issued by Cornell University, INSEAD, and WIPO and the IMD World Competitiveness Yearbook (2014). After confirming the distributions normality, Pearson correlation analysis was made with results showing high linear correlations between the three indexes. Findings: The results of the correlation analysis using Pearson correlation coefficient (all correlation coefficients are greater than 0.73) give a strong support to the conclusion that there is indeed a high correlation (and a possible relationship) between social sustainability, innovation and competitiveness at country level. Research limitations/implications: Further research is advisable to better understand the factors that contribute to the presented results and to establish a global paradigm linking these three main constructs (social sustainability, innovation, and competitiveness). Some authors consider that these measurements are not fully supported (e.g. due to different countries standards), however, it is assumed these differing underlying methodological approaches, by being used in conjunction, can be considered as a set of reliable and useful performance indicators. Practical implications: The results highlight the simultaneous relationship between social sustainability, innovation and competitiveness superior performance and the need to take that these considerations into business and operating models. Social implications: This research suggests that sustainability and innovation policies, strategies and practices are relevant for countries competitiveness and should be promoted particularly in countries ranked low on sustainability and innovation global scoring indexes. Originality/value: This is one of the few studies addressing the relationships between sustainability, innovation and competitiveness at country level.
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PURPOSE: 1. Identify differences in optic nerve sheath diameter (ONSD) as an indirect measure of intracranial pressure (ICP) in glaucoma patients and a healthy population. 2. Identify variables that may correlate with ONSD in primary open-angle glaucoma (POAG) and normal tension glaucoma (NTG) patients. METHODS: Patients with NTG (n = 46) and POAG (n = 61), and healthy controls (n = 42) underwent B-scan ultrasound measurement of ONSD by an observer masked to the patient diagnosis. Intraocular pressure (IOP) was measured in all groups, with additional central corneal thickness (CCT) and visual field defect measurements in glaucomatous patients. Only one eye per patient was selected. Kruskal-Wallis or Mann-Whitney were used to compare the different variables between the diagnostic groups. Spearman correlations were used to explore relationships among these variables. RESULTS: ONSD was not significantly different between healthy, NTG and POAG patients (6.09 ± 0.78, 6.03 ± 0.69, and 5.71 ± 0.83 respectively; p = 0.08). Visual field damage and CCT were not correlated with ONSD in either of the glaucoma groups (POAG, p = 0.31 and 0.44; NTG, p = 0.48 and 0.90 respectively). However, ONSD did correlate with IOP in NTG patients (r = 0.53, p < 0.001), while it did not in POAG patients and healthy controls (p = 0.86, p = 0.46 respectively). Patient's age did not relate to ONSD in any of the groups (p > 0.25 in all groups). CONCLUSIONS: Indirect measurements of ICP by ultrasound assessment of the ONSD may provide further insights into the retrolaminar pressure component in glaucoma. The correlation of ONSD with IOP solely in NTG patients suggests that the translaminar pressure gradient may be of particular importance in this type of glaucoma.
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PURPOSE: To describe the anatomy and imaging findings of the prostatic arteries (PAs) on multirow-detector pelvic computed tomographic (CT) angiography and digital subtraction angiography (DSA) before embolization for symptomatic benign prostatic hyperplasia (BPH). MATERIALS AND METHODS: In a retrospective study from May 2010 to June 2011, 75 men (150 pelvic sides) underwent pelvic CT angiography and selective pelvic DSA before PA embolization for BPH. Each pelvic side was evaluated regarding the number of independent PAs and their origin, trajectory, termination, and anastomoses with adjacent arteries. RESULTS: A total of 57% of pelvic sides (n = 86) had only one PA, and 43% (n = 64) had two independent PAs identified (mean PA diameter, 1.6 mm ± 0.3). PAs originated from the internal pudendal artery in 34.1% of pelvic sides (n = 73), from a common trunk with the superior vesical artery in 20.1% (n = 43), from the anterior common gluteal-pudendal trunk in 17.8% (n = 38), from the obturator artery in 12.6% (n = 27), and from a common trunk with rectal branches in 8.4% (n = 18). In 57% of pelvic sides (n = 86), anastomoses to adjacent arteries were documented. There were 30 pelvic sides (20%) with accessory pudendal arteries in close relationship with the PAs. No correlations were found between PA diameter and patient age, prostate volume, or prostate-specific antigen values on multivariate analysis with logistic regression. CONCLUSIONS: PAs have highly variable origins between the left and right sides and between patients, and most frequently arise from the internal pudendal artery.
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In the last two decades, small strain shear modulus became one of the most important geotechnical parameters to characterize soil stiffness. Finite element analysis have shown that in-situ stiffness of soils and rocks is much higher than what was previously thought and that stress-strain behaviour of these materials is non-linear in most cases with small strain levels, especially in the ground around retaining walls, foundations and tunnels, typically in the order of 10−2 to 10−4 of strain. Although the best approach to estimate shear modulus seems to be based in measuring seismic wave velocities, deriving the parameter through correlations with in-situ tests is usually considered very useful for design practice.The use of Neural Networks for modeling systems has been widespread, in particular within areas where the great amount of available data and the complexity of the systems keeps the problem very unfriendly to treat following traditional data analysis methodologies. In this work, the use of Neural Networks and Support Vector Regression is proposed to estimate small strain shear modulus for sedimentary soils from the basic or intermediate parameters derived from Marchetti Dilatometer Test. The results are discussed and compared with some of the most common available methodologies for this evaluation.
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In the last two decades, small strain shear modulus became one of the most important geotechnical parameters to characterize soil stiffness. Finite element analysis have shown that in-situ stiffness of soils and rocks is much higher than what was previously thought and that stress-strain behaviour of these materials is non-linear in most cases with small strain levels, especially in the ground around retaining walls, foundations and tunnels, typically in the order of 10−2 to 10−4 of strain. Although the best approach to estimate shear modulus seems to be based in measuring seismic wave velocities, deriving the parameter through correlations with in-situ tests is usually considered very useful for design practice.The use of Neural Networks for modeling systems has been widespread, in particular within areas where the great amount of available data and the complexity of the systems keeps the problem very unfriendly to treat following traditional data analysis methodologies. In this work, the use of Neural Networks and Support Vector Regression is proposed to estimate small strain shear modulus for sedimentary soils from the basic or intermediate parameters derived from Marchetti Dilatometer Test. The results are discussed and compared with some of the most common available methodologies for this evaluation.
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HIV-infected patients may be affected by a variety of renal disorders. Portugal has a high incidence of HIV2 infection and a low prevalence of HIV-infected patients under dialysis treatment. The aim of this study was to characterise the type of renal disease in Portuguese HIV-infected patients and to determine if HIV2 infection is associated to renal pathology. Only 60 of the 5158 HIV-infected patients followed in our hospital underwent renal biopsy. Clinical and laboratory data and the type of renal disease were reviewed. Male gender was predominant (76.7%), as was Caucasian race (78.3%). Mean age was 37.9±10.6 years. The majority had criteria for AIDS, 66% were on combined antiretroviral therapy and 18.3% were on dialysis. The predominant lesions were immunecomplex glomerulonephritis (n=19), tubulointerstitial nephropathy (n=12), focal segmental glomerulosclerosis(n=11), followed by HIVAN (n=8). Other patterns(amyloidosis, vasculitis, minimal change lesion) were observed. Only three patients were HIV2 infected, and presented diabetic nephropathy, acute tubular necrosis and tubulointerstitial nephritis. No correlations between clinical findings and renal pathology were found. In conclusion, renal disease in HIV patients has a broad spectrum, and renal biopsy remains the gold standard for establishing the diagnosis and guide treatment. Renal disease is not frequent in HIV2-infected patients, and, when present, is probably not directly associated with HIV infection.
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The recent developments on Hidden Markov Models (HMM) based speech synthesis showed that this is a promising technology fully capable of competing with other established techniques. However some issues still lack a solution. Several authors report an over-smoothing phenomenon on both time and frequencies which decreases naturalness and sometimes intelligibility. In this work we present a new vowel intelligibility enhancement algorithm that uses a discrete Kalman filter (DKF) for tracking frame based parameters. The inter-frame correlations are modelled by an autoregressive structure which provides an underlying time frame dependency and can improve time-frequency resolution. The system’s performance has been evaluated using objective and subjective tests and the proposed methodology has led to improved results.
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RESUMO:O objectivo deste estudo foi analisar a relação entre mobilidade funcional, risco de queda, nível de actividade física e percepção de saúde de 34 indivíduos praticantes (n=18) e não praticantes (n=16) de exercício físico duas ou mais vezes por semana durante pelo menos 45 minutos, residentes na comunidade e ambulatórios. Tipo de estudo: transversal exploratório-descritivo. Metodologia: foi feito um levantamento das variáveis de caracterização (idade, sexo, habilitações literárias, situação sócio-económica, situação familiar) e do estado cognitivo e estado emocional/depressão (Mini-Mental State Examination e Geriatric Depression Scale). As variáveis em análise foram: a mobilidade funcional avaliada através do Timed up and GoTest, o risco de queda medido com o Funtional Reach Test, o nível de actividade física avaliado através do Questionário Internacional de Actividade Física (IPAQ) e a percepção de saúde medida através do SF-6D. Foi também questionada a prática de alguma modalidade de exercício físico, da sua frequência e duração. Os dados foram analisados através de estatística descritiva, foi realizada uma regressão linear múltipla e uma análise bivariada das correlações, utilizando o coeficiente de correlação linear de Pearson (p ≤ 0,05).Resultados: verificou-se que, na amostra global, a maioria dos indivíduos apresentou uma mobilidade funcional considerada normal (TUG<10 segundos), e um risco de queda moderado (FRT entre 15,24 e 25,40 cm), embora sem diferenças entre os grupos em análise. A actividade física apresentou uma duração média de 685,88±540,16 minutos por semana, sendo que 18 indivíduos praticavam exercício físico pelo menos 45 minutos e duas ou mais vezes por semana.A percepção do estado de saúde foi bastante satisfatória, sendo a pontuação média do SF-6D de 0,915±0,067. A análise entre grupos demonstrou que o grupo que praticava exercício físico apresentava um maior número de indivíduos na faixa etária dos 65-74 anos, tinha mais escolarização e melhor estado cognitivo. Estes indivíduos eram fisicamente mais activos e faziam-o, na sua maioria, com uma frequência bissemanal, apenas um desempenhando uma modalidade de intensidade vigorosa. A análise estatística demonstrou que: a mobilidade funcional e o risco de queda eram mais desfavoráveis nos indivíduos com mais idade; o estado cognitivo estava associado a maior mobilidade funcional; uma boa mobilidade funcional correspondeu a um risco de queda reduzido, a mais prática de actividade física, a melhor percepção do estado de saúde e a manutenção do estado cognitivo. Os indivíduos com menor risco de queda apresentaram melhor estado cognitivo e emocional. E este último correspondeu a uma melhor percepção do estado de saúde e a um melhor estado cognitivo. Conclusão: a manutenção da mobilidade funcional reduz o risco de queda aumenta a prática de actividade física e melhora a percepção de saúde de indivíduos com 65 ou mais anos residentes na comunidade.--------- ABSTRACT: Objective: the aim of this study was to analyze the relationship between functional mobility, falls risk, level of physical activity and health perception in a sample of 34 subjects, 18 that practice exercise two or more times a week for at least 45 minutes and 16 that don’t practice exercise, residents and community. Designs: cross-sectional exploratory-descriptive survey. Methods: descriptive variables are age, sex, education, socio-economic level, family status, cognitive status (Mini-Mental State Examination) and emotional status/depression (Geriatric Depression Scale). We analyze the functional mobility with the Timed up and Go Test, the falls risk with Functional Reach Test, the level of physical activity with the International Physical Activity Questionnaire (IPAQ) and health perception with SF-6D. We also questioned the practice of exercise, their frequency and duration. Data were analyzed using descriptive statistics, a multiple linear regression analysis and bivariate correlations, using the linear correlation coefficient of Pearson (p ≤ 0.05). Results: we found that, in the total sample, most individuals had considered a normal functional mobility (TUG <10 seconds), and a moderate falls risk (FRT between 15.24 and 25.40 cm), but no difference between groups. Physical activity showed an mean of 685.88 ± 540.16 minutes per week, with 18 individuals pratice physical exercise at least 45 minutes and two or more times per week. The mean score of the SF-6D was 0.915 ± 0.067 and the perception of health was satisfactory. The analysis between groups showed that the group that practice physical exercise had a greater number of individuals aged 65-74 years, had more schooling and better cognitive status. These subjects were more physically active and mostly did it two times a weak and only one playing a kind of vigorous intensity. The multiple linear regression and correlations, using the linear correlation coefficient of Pearson (p≤0.05) showed that: functional mobility and fall risk decrease with age increase. The cognitive status was associated with greater functional mobility, a good functional mobility corresponded to a reduced falls risk, more physical activity, a better perception of health status and maintenance of cognitive status. Subjects with lower falls risk had better cognitive and emotional state. And subjects with a better emotional status have a better health perception and better cognitive status. Conclusion: the maintenance of functional mobility reduces falls risk, increase physical activity and improves health perception of individuals with 65 years or older living in the community.
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O presente trabalho pretende abordar aspectos relacionados com o controlo de compactação em aterros, com base na avaliação de parâmetros “in situ”, tais como: pesos volúmicos, teores em água, graus de compactação e módulos de deformabilidade. Recorrendo aos métodos correntes no controlo de compactação, como o ensaio de carga em placa, gamadensímetro, garrafa e ao ensaio de deflectómetro de impacto portátil. Visa-se comparar os resultados obtidos, nas diferentes condições, de modo a possibilitar alcançar correlações entre os ensaios, bem como determinar aqueles que apresentam maior grau de confiança técnico e vantagens operacionais e económicas. De modo a garantir os índices de qualidade da obra é necessário fazer cumprir os critérios exigidos pelo caderno de encargos, nomeadamente nos parâmetros de avaliação do controlo de compactação, para que estas satisfaçam o seu estado funcional e estrutural. Neste tipo de obras os cadernos de encargos de referência em Portugal são os das Estradas de Portigal (EP) e da Brisa, Auto-estradas de Portugal (Brisa), os quais se baseiam em recomendações de classificações de solos. No contexto experimental, foram efectuados dois estudos com condições e materiais diferentes, em obras pertencentes à empresa Mota-Engil Engenharia e Construções, S.A. Nas campanhas de ensaios foram realizados ensaios “in situ” na obra da Subconcessão do Douro Interior – Lote 6 – IC5 – Troço Murça/ Nó de Pombal nas camadas de sub-base e base num agregado de granulometria extensa, e na obra de modernização do troço ferroviário Bombel e Vidigal a Évora, em solos.
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Twelve strains of Trypanosoma cruzi isolated from wild reservoirs, triatomines, and chronic chagasic patients in the state of Paraná, southern Brazil, and classified as T. cruzi I and II, were used to test the correlation between genetic and biological diversity. The Phagocytic Index (PI) and nitric-oxide (NO) production in vitro were used as biological parameters. The PI of the T. cruzi I and II strains did not differ significantly, nor did the PI of the T. cruzi strains isolated from humans, triatomines, or wild reservoirs. There was a statistical difference in the inhibition of NO production between T. cruzi I and II and between parasites isolated from humans and the strains isolated from triatomines and wild reservoirs, but there was no correlation between genetics and biology when the strains were analyzed independently of the lineages or hosts from which the strains were isolated. There were significant correlations for Randomly Amplified Polymorphic Deoxyribonucleic acid (RAPD) and biological parameters for T. cruzi I and II, and for humans or wild reservoirs when the lineages or hosts were considered individually.
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A thesis submitted in fulfilment of the requirements for the degree of Masters in Molecular Genetics and Biomedicine
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Dissertação de Mestrado apresentado ao Instituto de Contabilidade e Administração do Porto para a obtenção do grau de Mestre em Contabilidade e Finanças, sob orientação do Doutor Carlos Quelhas Martins