Fatores de inibição na compra on-line

O objetivo deste trabalho consiste em identificar as barreiras ao comércio eletrónico em Portugal, face a outros países europeus. Foi adotado um modelo para compreender a variação das práticas de comércio eletrónico em Portugal com base em quatro dimensões: Risco Percebido, Facilidade de Uso Percebida, Utilidade Percebida, e Experiência Online. Este modelo foi testado numa amostra de 101 indivíduos, tendo sido possível encontrar uma correlação positiva entre as práticas de comércio eletrónico e a facilidade de utilização percebida, a utilidade percebida e a experiência online.The purpose of this paper is to understand the obstacles to e-commerce in Portugal compared to other European countries. In order to understand the variation of the e-commerce practices in Portugal, a model was proposed. In this model four constructs were used as explanatory variables: Perceived Risks; Perceived Ease of Use; Perceived Usefulness; and Online Experience. This model was tested in a sample of 101 respondents which allowed finding a positive correlation between the E-commerce Practices and the Perceived Ease of Use, the Perceived Usefulness, and the Online Experience constructsinfo:eu-repo/semantics/publishedVersio

NEW EQUATIONS TO DETERMINE EXERCISE INTENSITY USING DIFFERENT EXERCISE MODES

The purpose of this study was to determine new equations from the relationship of %·VO2max versus %HRmax, based on direct measures of oxygen uptake, in four exercise modes (leg cycling, rowing, stepping and running), in young adult females and males with low risk for cardiovascular disease. Ten adult males and ten females volunteered for the study. The participants performed an incremental test for each exercise mode until exhaustion. Regression analyses were carried out for each participant at a target % of VO2max and %HRmax was computed. At 40-90%·VO2max, the regression equations predicted similar values of %HRmax for males and females in the four exercise modes. In contrast, estimated %HRmax for cycling was higher at 40-70%·VO2max, when compared with stepping and running. The results support the notion that a single equation to predict target heart rate values for both males and females can be applied. Furthermore, at light and moderate intensities, leg cycling produces different %·VO2max-%HRmax regression equations than stepping and running

Revisão bibliográfica e descrição de um caso clínico

O tumor glómico é uma lesão neoplásica benigna, geralmente única, que se desenvolve a partir de uma estrutura neuromioarterial existente na pele, o glomo. O glomo tem como função regular a circulação sanguínea e a temperatura corporal. É constituído por uma arteríola aferente, um vaso anastomótico chamado canal de Soucquet-Hoyer, envolto por fibras musculares lisas, uma veia eferente, fibras nervosas e cápsula periférica. Esta estrutura está distribuída por toda a superfície corporal, em particular nos leitos ungueais, polpas digitais, palmas das mãos e plantas dos pés. A apresentação típica do tumor glómico é caracterizada pela tríade clássica de sintomas de dor paroxística (80%), hipersensibilidade ao frio (63%) e localização precisa do ponto doloroso (100%). Trata-se de um tumor bastante raro e particularmente difícil de diagnosticar. A intenção deste trabalho é descrever um caso clínico sobre o tema, bem como uma revisão literária sobre o mesmo.Glomus tumor is a benign lesion that develops from a neuromyoarterial structure that exists in the skin, the glomus. Glomus function is to regulate blood circulation and body temperature. It consists of an afferent, anastomotic vessel called Soucquet-Hoyer canal, surrounded by smooth muscle fibers, an efferent vein, nerve fibers and peripheral capsule. This structure is distributed throughout the body surface, particularly in the nail beds, fingertips, palms of the hands and soles of the feet. Typical presentation of glomus tumor is characterized by the classical symptom triad of paroxysmal pain (80%), local hyperalgia (100%) and temperature sensibility to cold (63%). This consists of a very rare tumor and particularly difficult to diagnose. The intention of this work is to describe a clinical case about this subject, as well the literature review of the theme

Effect of relining on fiber post retention to root canal

One of the clinically relevant problems dentists face when restoring endodontically treated teeth is the mismatch between fiber post and post space diameters, which results in an excessively thick resin cement layer. Fiber post relining appears as a solution for this problem. OBJECTIVES: The aim of this study was to evaluate the effect of fiber post relining with composite resin on push-out bond strength. MATERIAL AND METHODS: Twenty bovine incisors were selected to assess post retention. The crowns were removed below the cementoenamel junction and the root canals were treated endodontically and flared with diamond burs. The roots were allocated into two groups (n=10): G1: fiber posts without relining and G2: fiber posts relined with composite resin. The posts were cemented with a dual-cured resin cement and the specimens were sectioned transversally. Three 1.5-mm thick slabs were obtained per root and identified as cervical, medium and apical thirds. The push-out test was performed at a crosshead speed of 0.5 mm/min until post dislodgement occurred. The failure mode of fractured specimens was analyzed under scanning electron microscopy. Data were analyzed by split-plot ANOVA and post-hoc Tukey's test at a pre-set alpha of 0.05. RESULTS: Relined fiber posts presented higher retention values than non-relined post in all thirds. No statistically significant differences (p>;0.05) were found among thirds for relined posts. All failures occurred at the interface between resin cement and root dentin. CONCLUSIONS: Relining with composite resin seems to be an effective method to improve the retention of fiber posts to flared root canals

Imunorreatividade para endotelina-1 no plasma e fluido folicular de eqüinos e bovinos

Endothelin-1, a recently isolated peptide, has been observed in different tissues and is involved in several reproductive functions. The objective of the present study was to determine the concentrations of immunoreactive endothelin-1 in the plasma of horses and cattle and in the follicular fluid of horses using a commercial radioimmunoassay kit. Mean immunoreactivity was 47.5%, the minimum detectable dose was 1 pg/tube and the interassay and intra-assay coefficients of variation were 2.36% and 7.26%, respectively. The parallelism between the standard curves and the curves determined with different volumes of plasma and follicular fluid validates the radioimmunoassay of endothelin-1 for these species. To our knowledge, this is the first report in the literature of detection of endothelin-1 in the plasma and follicular fluid of horses and in the plasma of cattle by radioimmunoassay. The present results suggest the use of the radioimmunoassay method employing commercial kits for the determination of endothelin-1 concentrations in horse and cattle plasma and horse follicular fluid because of its high sensitivity, accuracy and reproducibility, in order to study the multiple functions of endothelin-1 in these animals species, and especially in the endocrine-reproductive system.A endotelina-1, um peptídeo isolado recentemente, tem sido observada em diferentes tecidos e está envolvida em várias funções reprodutivas. Propusemo-nos a determinar as concentrações da endotelina-1 por radioimunoensaio no plasma de eqüinos e bovinos e no fluido folicular de eqüinos. Foram testados 2 tipos de inibidores de degradação protéica no plasma e fluido folicular. A imunorreatividade média foi de 47,5%, a dose mínima detectável foi de 1 pg/tubo e o coeficiente de variação inter e intra-ensaio foi de 2,36% e 7,26%, respectivamente. O paralelismo entre a curva padrão e as curvas determinadas com diferentes volumes de plasma e fluido folicular valida o radioimunoensaio de endotelina-1 para estas espécies. Segundo nosso conhecimento, este é o primeiro relato de literatura que detecta por radioimunoensaio a endotelina-1 no plasma e fluido folicular de eqüinos e plasma de bovinos. Os resultados do presente trabalho sugerem a utilização do método de radioimunoensaio utilizando-se kits comerciais para a determinação das concentrações da endotelina-1 no plasma de eqüinos e bovinos e fluido folicular de eqüinos, pelo fato de este apresentar alta sensibilidade, precisão e reprodutibilidade, podendo assim ser utilizado no estudo de múltiplas funções da endotelina-1 nestas espécies animais e, em especial, no sistema endócrino-reprodutivo

Perfluoropolyethers: Development of an All-Atom Force Field for Molecular Simulations and Validation with New Experimental Vapor Pressures and Liquid Densities

A force field for perfluoropolyethers (PFPEs) based on the general optimized potentials for liquid simulations all-atom (OPLS-AA) force field has been derived in conjunction with experiments and ab initio quantum mechanical calculations. Vapor pressures and densities of two liquid PFPEs, perfluorodiglyme (CF3−O−(CF2−CF2−O)2−CF3) and perfluorotriglyme (CF3−O−(CF2−CF2−O)3−CF3), have been measured experimentally to validate the force field and increase our understanding of the physical properties of PFPEs. Force field parameters build upon those for related molecules (e.g., ethers and perfluoroalkanes) in the OPLS-AA force field, with new parameters introduced for interactions specific to PFPEs. Molecular dynamics simulations using the new force field demonstrate excellent agreement with ab initio calculations at the RHF/6-31G* level for gas-phase torsional energies (<0.5 kcal mol−1 error) and molecular structures for several PFPEs, and also accurately reproduce experimentally determined densities (<0.02 g cm−3 error) and enthalpies of vaporization derived from experimental vapor pressures (<0.3 kcal mol−1). Additional comparisons between experiment and simulation show that polyethers demonstrate a significant decrease in enthalpy of vaporization upon fluorination unlike related molecules (e.g., alkanes and alcohols). Simulation suggests this phenomenon is a result of reduced cohesion in liquid PFPEs due to a reduction in localized associations between backbone oxygen atoms and neighboring molecules