932 resultados para combinatorial protocol in multiple linear regressions


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Com a utilização da Internet a fazer cada vez mais parte do dia-a-dia das pessoas, foram muitas as empresas que se adaptaram ao fenómeno E-commerce e outras até se transformaram por completo perante o mesmo. Com normalidade o número de lojas online aumentou assim como as compras através das mesmas. Em igual crescimento está a utilização dos smartphones para aceder à Internet, o que fez com que o tipo de comércio online já existente M-commerce ganhasse uma nova força e posição nas vendas através da Internet. Assim para compreender os fatores que influenciam a intenção de compra do consumidor em plataformas de E-commerce e M-commerce e em qual têm mais influência, realizou-se o presente estudo comparativo. Por forma a realizar este estudo aplicou-se um modelo, que analisa a influência da utilidade percebida, facilidade de uso percebida, influência social, condições facilitadoras, confiança e risco percebido na intenção de compra do consumidor. Foram realizadas duas regressões lineares múltiplas e dois testes à correlação de Spearman para testar as hipóteses propostas. A amostra é constituída por 76 indivíduos do sexo masculino e 125 do sexo feminino, com idades compreendidas entre os 18 e os 65 anos, sendo que a maioria está entre os 18 e os 35 anos. Dos principais resultados conclui-se que a utilidade percebida tem mais influência na intenção de compra em plataformas de E-commerce, na facilidade de uso percebida não existe diferença estatisticamente significativa entre plataformas e a influência social e a confiança têm mais influência em plataformas de M-commerce. Não foi possível comprovar a influência das condições facilitadoras e do risco percebido na intenção de compra do consumidor em ambas as plataformas.

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Introdução: A cintigrafia óssea é um dos exames mais frequentes em Medicina Nuclear. Esta modalidade de imagem médica requere um balanço apropriado entre a qualidade de imagem e a dose de radiação, ou seja, as imagens obtidas devem conter o número mínimo de contagem necessárias, para que apresentem qualidade considerada suficiente para fins diagnósticos. Objetivo: Este estudo tem como principal objetivo, a aplicação do software Enhanced Planar Processing (EPP), nos exames de cintigrafia óssea em doentes com carcinoma da mama e próstata que apresentam metástases ósseas. Desta forma, pretende-se avaliar a performance do algoritmo EPP na prática clínica em termos de qualidade e confiança diagnóstica quando o tempo de aquisição é reduzido em 50%. Material e Métodos: Esta investigação teve lugar no departamento de Radiologia e Medicina Nuclear do Radboud University Nijmegen Medical Centre. Cinquenta e um doentes com suspeita de metástases ósseas foram administrados com 500MBq de metilenodifosfonato marcado com tecnécio-99m. Cada doente foi submetido a duas aquisições de imagem, sendo que na primeira foi seguido o protocolo standard do departamento (scan speed=8 cm/min) e na segunda, o tempo de aquisição foi reduzido para metade (scan speed=16 cm/min). As imagens adquiridas com o segundo protocolo foram processadas com o algoritmo EPP. Todas as imagens foram submetidas a uma avaliação objetiva e subjetiva. Relativamente à análise subjetiva, três médicos especialistas em Medicina Nuclear avaliaram as imagens em termos da detetabilidade das lesões, qualidade de imagem, aceitabilidade diagnóstica, localização das lesões e confiança diagnóstica. No que respeita à avaliação objetiva, foram selecionadas duas regiões de interesse, uma localizada no terço médio do fémur e outra localizada nos tecidos moles adjacentes, de modo a obter os valores de relação sinal-ruído, relação contraste-ruído e coeficiente de variação. Resultados: Os resultados obtidos evidenciam que as imagens processadas com o software EPP oferecem aos médicos suficiente informação diagnóstica na deteção de metástases, uma vez que não foram encontradas diferenças estatisticamente significativas (p>0.05). Para além disso, a concordância entre os observadores, comparando essas imagens e as imagens adquiridas com o protocolo standard foi de 95% (k=0.88). Por outro lado, no que respeita à qualidade de imagem, foram encontradas diferenças estatisticamente significativas quando se compararam as modalidades de imagem entre si (p≤0.05). Relativamente à aceitabilidade diagnóstica, não foram encontradas diferenças estatisticamente significativas entre as imagens adquiridas com o protocolo standard e as imagens processadas com o EPP software (p>0.05), verificando-se uma concordância entre os observadores de 70.6%. Todavia, foram encontradas diferenças estatisticamente significativas entre as imagens adquiridas com o protocolo standard e as imagens adquiridas com o segundo protocolo e não processadas com o software EPP (p≤0.05). Para além disso, não foram encontradas diferenças estatisticamente significativas (p>0.05) em termos de relação sinal-ruído, relação contraste-ruído e coeficiente de variação entre as imagens adquiridas com o protocolo standard e as imagens processadas com o EPP. Conclusão: Com os resultados obtidos através deste estudo, é possível concluir que o algoritmo EPP, desenvolvido pela Siemens, oferece a possibilidade de reduzir o tempo de aquisição em 50%, mantendo ao mesmo tempo uma qualidade de imagem considerada suficiente para fins de diagnóstico. A utilização desta tecnologia, para além de aumentar a satisfação por parte dos doentes, é bastante vantajosa no que respeita ao workflow do departamento.

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This study aimed to identify physiological markers in superficially scalded 'Rocha' pear (Pyrus communis L 'Rocha') that would relate to chlorophyll a fluorescence (CF), allowing a non-invasive diagnosis of the disorder. Conditions chosen before shelf life provided two fruit groups with different developing patterns and severity of superficial scald: T fruit fully developed the disorder in storage, while C fruit developed it progressively throughout shelf life. Principal component analysis (PCA) of all the measured variables, and simple linear correlations among several major parameters and scald index (SI)/shelf life showed that scald and ripening/aging were concurring processes, and that it was not possible to isolate a particular variable that could deliver a direct non-invasive diagnosis of the disorder. For both fruit groups the SI resulted from the balance between the reducing power (OD200) and the content of conjugated trienols (CTos) and alpha-farnesene (alpha-Farn) in the fruit peel. At OD200 > 150 there was a linear relationship between CTos and OD200, suggesting that the level of antioxidants was self-adjusted in order to compensate the CTos level. However, at OD200 < 150 this relationship disappeared. A consistent linear relationship between dos and alpha-Farn existed throughout shelf life in both fruit groups, contrarily to the early storage stage, when those compounds do not relate linearly. The CF variables F-0, F-v/F-m, and the colorimetric variables, L* and h degrees were used in multi-linear regressions with other physiological variables. The regressions were made on one of the fruit groups and validated through the other. Reliable regressions to alpha-Farn and CTos were obtained (R approximate to 0.6; rmsec approximate to rmsep). Our results suggest that a model based on CF and colorimetric parameters could be used to diagnose non-invasively both the contents and the relationship between alpha-Farn and CTos and hence the stage of scald development. (C) 2011 Elsevier By. All rights reserved.

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O objetivo do estudo foi analisar e interpretar o currículo que é proporcionado nas escolas secundárias da Região de Lisboa e de como o currículo operacional está relacionado com as orientações educacionais (OE) dos professores. Assim, por um lado quisemos saber como as OE se relacionam com os diferentes níveis de currículo e por outro como é que a finalidade curricular de promover estilos de vida ativos nos alunos é percecionada pelos professores. Este objetivo geral deu origem a cinco objetivos específicos de pesquisa que foram estudados em diferentes etapas da investigação numa abordagem quantitativa/qualitativa com a utilização de diferentes técnicas estatísticas. Na etapa extensiva estudou-se as OE de 352 professores de EF de 79 escolas com o ensino secundário geral através do VOI-SF (value orientation inventory – short form) validado através de uma técnica transcultural permitindo encontrar valores de referência das OE para Portugal. Os professores revelaram alta prioridade em Integração ecológica e Auto-realização e baixa prioridade nas restantes OE. O currículo operacional de EF revelou-se essencialmente desportivo e existiram diferenças estatisticamente significativas em relação às variáveis independentes estudadas (idade e experiência profissional). Através de regressões lineares múltiplas comprovou-se que existe uma relação entre as OE e a oferta curricular. Na etapa intensiva estudou-se 14 professores com perfis representativos das suas OE, examinando-se dez dimensões de análise representativas da interpretação e operacionalização do CNEF (análise de conteúdo). Constata-se que as OE influenciam a leitura, interpretação e operacionalização do currículo (e.g., a coeducação no ensino da EF). Dos 14 professores investigados foram selecionados dois professores com perfis de OE opostos para percebermos o comportamento das OE em contexto de sala de aula. Depois das entrevistas, observação e análise do planeamento constatou-se que os dois professores operacionalizam o conhecimento e o ensino/aprendizagem de forma diferenciada e de acordo com as suas OE.

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Introduction: Adiponectin, an adipocyte derived peptide, has anti-inflammatory and antiatherogenic effects, and improves insulin sensitivity. However, little is known about dietary predictors and their interactions with lifestyle on adiponectin concentrations, in apparently healthy young adults. Objective: To evaluate the associations between plasma concentrations of adiponectin with dietary components and lifestyle in apparently healthy young adults. Methods: Anthropometric and body composition, systolic and diastolic blood pressure, diet and lifestyle data of 157 healthy young adults, aged 18 and 35, were collected and analyzed. Blood samples were collected after fasting for 12 hours to determine adiponectin concentrations. Dietary and anthropometric indexes were calculated and analyzed. Results: Adiponectin concentrations were significantly higher for women compared to men; and there was an indirect and significant correlation between adiponectin concentrations with BMI. There was a significant association between adiponectin concentrations with the healthy eating index, calories, lipids, proteins, fibers, riboflavin, and phosphorus, among others; and a tendency with carbohydrates and niacin. In multiple linear regression analysis, fiber and riboflavin (r² = 0.0928; p = 0.0013) and carbohydrates and phosphorus were associated with the concentrations of adiponectin. The association with carbohydrates and phosphorus suffered interaction with gender (r²= 0.2400; p < 0.0001), as well as the association with phosphorus also suffered interaction with physical activity (r²= 0.1275; p = 0.0003). Conclusion: Plasma concentrations of adiponectin, in healthy young adults, seem to be modulated by components of diet depending on gender and physical activity.

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This study aimed to identify physiological markers in superficially scalded 'Rocha' pear (Pyrus communis L 'Rocha') that would relate to chlorophyll a fluorescence (CF), allowing a non-invasive diagnosis of the disorder. Conditions chosen before shelf life provided two fruit groups with different developing patterns and severity of superficial scald: T fruit fully developed the disorder in storage, while C fruit developed it progressively throughout shelf life. Principal component analysis (PCA) of all the measured variables, and simple linear correlations among several major parameters and scald index (SI)/shelf life showed that scald and ripening/aging were concurring processes, and that it was not possible to isolate a particular variable that could deliver a direct non-invasive diagnosis of the disorder. For both fruit groups the SI resulted from the balance between the reducing power (OD200) and the content of conjugated trienols (CTos) and alpha-farnesene (alpha-Farn) in the fruit peel. At OD200 > 150 there was a linear relationship between CTos and OD200, suggesting that the level of antioxidants was self-adjusted in order to compensate the CTos level. However, at OD200 < 150 this relationship disappeared. A consistent linear relationship between dos and alpha-Farn existed throughout shelf life in both fruit groups, contrarily to the early storage stage, when those compounds do not relate linearly. The CF variables F-0, F-v/F-m, and the colorimetric variables, L* and h degrees were used in multi-linear regressions with other physiological variables. The regressions were made on one of the fruit groups and validated through the other. Reliable regressions to alpha-Farn and CTos were obtained (R approximate to 0.6; rmsec approximate to rmsep). Our results suggest that a model based on CF and colorimetric parameters could be used to diagnose non-invasively both the contents and the relationship between alpha-Farn and CTos and hence the stage of scald development. (C) 2011 Elsevier By. All rights reserved.

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We report for the first time, rogue waves generation in a mode-locked fiber laser that worked in multiple-soliton state in which hundreds of solitons occupied the whole laser cavity. Using real-time spatio-temporal intensity dynamics measurements, it is unveiled that nonlinear soliton collision accounts for the formation of rogue waves in this laser state. The nature of interactions between solitons are also discussed. Our observation may suggest similar formation mechanisms of rogue waves in other systems.

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Multiple Sclerosis (MS), an idiopathic progressive immune-mediated neurological disorder of the central nervous system (CNS), is characterized by recurrent episodes of inflammatory demyelination and consequent axonal deterioration. It accounts for functional deterioration and lasting disability among young adults. A body of literature demonstrates that physical activity counteracts fatigue and depression and may improve overall quality of life in MS patients. Furthermore, much data indicates that exercise ameliorates chronic neuroinflammation and its related pathologies by tipping cytokine profiles toward an anti-inflammatory signature. Recent data has focused on the direct impact of exercise training on the innate immune system by targeting toll-like receptors (TLRs), signaling pattern recognition receptors that govern the innate immune response, shedding light on the physiological role of TLRs in health and disease. Indeed, TLRs continue to emerge as players in the neuroinflammatory processes underpinning MS. This review will highlight evidence that physical activity and exercise are potential immunomodulatory therapies, targeting innate signaling mechanism(s) to modulate MS symptom development and progression.

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Introduction: A higher frequency of sleep and breathing disorders in Multiple System Atrophy (MSA) populations is documented in literature. The analysis of disease progression and prognosis in patients with sleep and breathing disorders could shed light on specific neuropathology and pathophysiology of MSA. Objective: To characterize sleep disorders and their longitudinal modifications during disease course in MSA patients, and to determine their prognostic value. Methods: This is a retrospective and prospective cohort study including 182 MSA patients (58.8% males). Type of onset was defined by the first reported motor or autonomic symptom/sign related to MSA. The occurrence of symptoms/signs and milestones of disease progression and their latency were collected. REM sleep behaviour disorder (RBD) and stridor were video-polysomnography (VPSG)-confirmed. VPSG recordings were analysed in a standardized fashion during the disease course. Survival data were based on time to death from the first symptom of disease. Results: Isolated RBD represented the first MSA symptom in 30% of patients, preceding disease onset according to international criteria with a median of 3(1–5) years. Patients developing early stridor or presenting with RBD at disease onset showed a more rapid and severe disease progression. These features had independent negative prognostic value for survival. Sleep architecture was characterized by peculiar features which could represent negative markers in MSA prognosis. Patients with stridor treated with tracheostomy showed a reduced risk of death. Conclusions: This is one of the first studies focusing on longitudinal progression of sleep in MSA. Sleep disorders are key features of disease, playing a role in presentation, prognosis and progression. In our MSA cohort, RBD represented the most frequent mode of disease presentation. Moreover, some specific clinical and instrumental sleep features could represent a hallmark of MSA and could be involved in prognosis and, in particular, in sudden death and death during sleep.

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Torpor is a successful survival strategy displayed by several mammalian species to cope with harsh environmental conditions. A complex interplay of ambient, genetic and circadian stimuli acts centrally to induce a severe suppression of metabolic rate, usually followed by an apparently undefended reduction of body temperature. Some animals, such as marmots, are able to maintain this physiological state for months (hibernation), during which torpor bouts are periodically interrupted by short interbouts of normothermia (arousals). Interestingly, torpor adaptations have been shown to be associated with a large resistance towards stressors, such as radiation: indeed, if irradiated during torpor, hibernators can tolerate higher doses of radiation, showing an increased survival rate. New insights for radiotherapy and long-term space exploration could arise from the induction of torpor in non-hibernators, like humans. The present research project is centered on synthetic torpor (ST), a hypometabolic/hypothermic condition induced in a non-hibernator, the rat, through the pharmacological inhibition of the Raphe Pallidus, a key brainstem area controlling thermogenic effectors. By exploiting this procedure, this thesis aimed at: i) providing a multiorgan description of the functional cellular adaptations to ST; ii) exploring the possibility, and the underpinning molecular mechanisms, of enhanced radioresistance induced by ST. To achieve these aims, transcriptional and histological analysis have been performed in multiple organs of synthetic torpid rats and normothermic rats, either exposed or not exposed to 3 Gy total body of X-rays. The results showed that: i) similarly to natural torpor, ST induction leads to the activation of survival and stress resistance responses, which allow the organs to successfully adapt to the new homeostasis; ii) ST provides tissue protection against radiation damage, probably mainly through the cellular adaptations constitutively induced by ST, even though the triggering of specific responses when the animal is irradiated during hypothermia might play a role.

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Aim of the present study was to develop a statistical approach to define the best cut-off Copy number alterations (CNAs) calling from genomic data provided by high throughput experiments, able to predict a specific clinical end-point (early relapse, 18 months) in the context of Multiple Myeloma (MM). 743 newly diagnosed MM patients with SNPs array-derived genomic and clinical data were included in the study. CNAs were called both by a conventional (classic, CL) and an outcome-oriented (OO) method, and Progression Free Survival (PFS) hazard ratios of CNAs called by the two approaches were compared. The OO approach successfully identified patients at higher risk of relapse and the univariate survival analysis showed stronger prognostic effects for OO-defined high-risk alterations, as compared to that defined by CL approach, statistically significant for 12 CNAs. Overall, 155/743 patients relapsed within 18 months from the therapy start. A small number of OO-defined CNAs were significantly recurrent in early-relapsed patients (ER-CNAs) - amp1q, amp2p, del2p, del12p, del17p, del19p -. Two groups of patients were identified either carrying or not ≥1 ER-CNAs (249 vs. 494, respectively), the first one with significantly shorter PFS and overall survivals (OS) (PFS HR 2.15, p<0001; OS HR 2.37, p<0.0001). The risk of relapse defined by the presence of ≥1 ER-CNAs was independent from those conferred both by R-IIS 3 (HR=1.51; p=0.01) and by low quality (< stable disease) clinical response (HR=2.59 p=0.004). Notably, the type of induction therapy was not descriptive, suggesting that ER is strongly related to patients’ baseline genomic architecture. In conclusion, the OO- approach employed allowed to define CNAs-specific dynamic clonality cut-offs, improving the CNAs calls’ accuracy to identify MM patients with the highest probability to ER. As being outcome-dependent, the OO-approach is dynamic and might be adjusted according to the selected outcome variable of interest.

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Objetivou-se descrever e avaliar a influência da renda sobre a participação da alimentação fora do domicílio no Brasil. Utilizaram-se dados coletados pela Pesquisa de Orçamentos Familiares realizada em 2002/2003 (POF 2002/2003), pelo Instituto Brasileiro de Geografia e Estatística. Analisaram-se os registros dos gastos com aquisições de alimentos e bebidas consumidos fora do domicílio. A associação entre a participação da alimentação fora do domicílio e a renda, ajustada para atributos sócio-demográficos, foi estudada por meio de modelos de regressão utilizados para estimação de coeficientes de elasticidade-renda. A alimentação fora do domicílio representou 21% do total dos gastos com alimentação; destaque-se que o incremento de 10% na renda aumentaria em 3% a participação da alimentação fora do domicílio. O efeito da renda sobre a participação da alimentação fora, ainda que sempre positivo, diminui conforme elevação da renda, sendo alto nos domicílios com renda inferior a R$68,70 per capita/mês. Há influência da renda nos gastos com alimentação fora do domicílio, assim a evolução favorável da renda resultará em aumento dessa forma de se alimentar.

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Left ventricular hypertrophy (LVH) is a complication that may result from chronic hypertension. While nitric oxide (NO) deficiency has been associated with LVH, inconsistent results have been reported with regards to the association of endothelial NO synthase (eNOS) polymorphisms and LVH in hypertensive patients. This study aims to assess whether eNOS haplotypes are associated with LVH in hypertensive patients. This study included 101 healthy controls and 173 hypertensive patients submitted to echocardiography examination. Genotypes for three eNOS polymorphisms were determined: a single-nucleotide polymorphism in the promoter region (T-786C) and in exon 7 (Glu298Asp), and variable number of tandem repeats in intron 4. We found no significant association between eNOS genotypes and hypertension or with LVH (all p>0.05). However, while we found two eNOS haplotypes associated with variable risk of hypertension (all p<0.05), we found no significant associations between eNOS haplotypes and LVH (all p>0.05), even after adjustment in multiple linear regression analysis. These findings suggest that eNOS haplotypes that have been associated with variable susceptibility to hypertension were not associated with LVH in hypertensive patients. Further studies are necessary to examine whether other genes downstream may interact with eNOS polymorphisms and predispose to LVH in hypertensive patients.