Effect of butadiene/styrene ratio, block structure and carbon nanotube content on the mechanical and electrical properties of thermoplastic elastomers after UV ageing

Thermoplastic elastomers based on a triblock copolymer styrene-butadiene-styrene (SBS) with different butadiene/styrene ratios, block structure and carbon nanotube (CNT) content were submitted to accelerated weathering in a Xenontest set up, in order to evaluate their stability to UV ageing. It was concluded that ageing mainly depends on butadiene/styrene ratio and block structure, with radial block structures exhibiting a faster ageing than linear block structures. Moreover, the presence of carbon nanotubes in the SBS copolymer slows down the ageing of the copolymer. The evaluation of the influence of ageing on the mechanical and electrical properties demonstrates that the mechanical degradation is higher for the C401 sample, which is the SBS sample with the largest butadiene content and a radial block structure. On the other hand, a copolymer derivate from SBS, the styrene-ethylene/butadiene-styrene (SEBS) sample, retains a maximum deformation of ~1000% after 80 h of accelerated ageing. The hydrophobicity of the samples decreases with increasing ageing time, the effect being larger for the samples with higher butadiene content. It is also verified that cytotoxicity increases with increasing UV ageing with the exception of SEBS, which remains not cytotoxic up to 80 h of accelerated ageing time, demonstrating its potential for applications involving exposition to environmental conditions.

TP perturbation of TN matrices and totally positive directions

Here, we define and consider (linear) TP-directions and TP-paths for a totally nonnegative matrix, in an effort to more deeply understand perturbation of a TN matrix to a TP matrix. We give circumstances in which a TP-direction exists and an example to show that they do not always exist. A strategy to give (nonlinear) TP-paths is given (and applied to this example). A long term goal is to understand the sparsest TP-perturbation for application to completion problems.

Clinical characteristics of women diagnosed with carcinoma who tested positive for cervical and anal high-risk human papillomavirus DNA and E6 RNA

High-risk human papillomavirus (hrHPV) is an essential cause of cervical carcinoma and is also strongly related to anal cancer development. The hrHPV E6 oncoprotein plays a major role in carcinogenesis. We aimed to evaluate the frequency of hrHPV DNA and E6 oncoprotein in the anuses of women with cervical carcinoma. We analyzed 117 women with cervical cancer and 103 controls for hrHPV and the E6 oncogene. Positive test results for a cervical carcinoma included 66.7 % with hrHPV-16 and 7.7 % with hrHPV-18. One case tested positive for both HPV variants (0.9 %). The samples from the anal canal were positive for HPV-16 in 59.8 % of the cases. Simultaneous presence of HPV in the cervix and anal canal was found in 53.8 % of the cases. Regarding expression of E6 RNA, positivity for HPV-16 in the anal canal was found in 21.2 % of the cases, positivity for HPV-16 in the cervix was found in 75.0 %, and positivity for HPV-18 in the cervix was found in 1.9 %. E6 expression in both the cervix and anal canal was found in 19.2 % of the cases. In the controls, 1 % tested positive for HPV-16 and 0 % for HPV-18. Anal samples from the controls showed a hrHPV frequency of 4.9 % (only HPV16). The presence of hrHPV in the anal canal of women with cervical cancer was detected at a high frequency. We also detected E6 RNA expression in the anal canal of women with cervical cancer, suggesting that these women are at risk for anal hrHPV infection.

Prevalence of excessive daytime sleepiness in Brazilian community-dwelling older adults with very low levels of schooling, and its association with sociodemographic characteristics and lifestyle: the Bambuí Health and Ageing Study (BHAS)

OBJECTIVE: Population-based studies on excessive daytime sleepiness (EDS) in older adults living in less developed countries are scarce. The purpose of this paper was to estimate the prevalence of EDS and its association with sociodemographic characteristics and lifestyle factors in Brazilian community-dwelling older adults. METHODS: The study was carried out in Bambuí, a city in the state of Minas Gerais, Brazil. EDS was defined as the presence of sleepiness in the last month occurring three or more times per week, with any interference in usual activities. The exploratory variables were: gender, age, skin color, marital status, schooling level, current employment status, religion, recent migration, smoking, binge drinking and physical activities during leisure time. RESULTS: Of 1,742 residents aged > 60 years, 1,514 (86.9%) participated. The prevalence of EDS was 13%. After adjustment for confounders, female gender and low schooling level remained positively and independently associated with EDS. CONCLUSIONS: The prevalence of EDS in the study population was within the range observed in studies carried out in developed countries. The most impressive finding was the association of EDS with schooling, indicating that even in a population with low levels of schooling, this was an important factor to explain the distribution of EDS.

The positive effect on ketamine as a priming adjuvant in antidepressant treatment.

Ketamine is an anesthetic with antidepressant properties. The rapid and lasting effect of ketamine observed in preclinical and clinical research makes it a promising therapeutic to improve current major depression (MD) treatment. Our work intended to evaluate whether the combined use of classic antidepressants (imipramine or fluoxetine) and ketamine would improve the antidepressant response. Using an animal model of depressive-like behavior, we show that the addition of ketamine to antidepressants anticipates the behavioral response and accelerates the neuroplastic events when compared with the use of antidepressants alone. In conclusion, our results suggest the need for a reappraisal of the current pharmacological treatment of MD.

Doppler echocardiographic evaluation of HIV-positive patients in different stages of the disease

OBJETIVE: To evaluate by Doppler echocardiography (DE) early abnormalities of ventricular function in HIV-positive patients, as well as other cardiac abnormalities that can be detected by this method, with special emphasis on mitral valve flow. METHODS: 84 HIV- positive patients, 59 with CD4 cell count >500/mm³ (Group A) and 25 with CD4 cell count <500/mm³ (Group B), were analyzed. CD4 cells were counted and matched with structural data and systolic and diastolic function of the left ventricle (LV), as analyzed by DE. The results were compared with those obtained in 47 healthy individuals (Group C). RESULTS: 8% of patients in Group B had mild pericardial effusion; 31.5% showed decreased systolic function of the LV, and 12% had moderate mitral regurgitation. A wave velocity from the mitral inflow was different among the 3 groups, being higher in Group B, where the deceleration time of the E wave of the mitral inflow and the E/A ratio were significantly lower with a normal value of the isovolumic relaxation time (IVRT). CONCLUSION: HIV-positive patients with a CD4 cell count >500/mm³ had no abnormalities by DE. Patients with a more advanced infection (those with a CD4 cell count <500/mm³), had a significantly abnormal LV systolic function and a higher incidence of pericardial effusion and mitral regurgitation. Mitral valve inflow by Doppler did not indicate diastolic dysfunction.

Oxygen therapy, continuous positive airway pressure, or noninvasive bilevel positive pressure ventilation in the treatment of acute cardiogenic pulmonary edema

OBJECTIVE: To compare the effects of 3 types of noninvasive respiratory support systems in the treatment of acute pulmonary edema: oxygen therapy (O2), continuous positive airway pressure, and bilevel positive pressure ventilation. METHODS: We studied prospectively 26 patients with acute pulmonary edema, who were randomized into 1 of 3 types of respiratory support groups. Age was 69±7 years. Ten patients were treated with oxygen, 9 with continuous positive airway pressure, and 7 with noninvasive bilevel positive pressure ventilation. All patients received medicamentous therapy according to the Advanced Cardiac Life Support protocol. Our primary aim was to assess the need for orotracheal intubation. We also assessed the following: heart and respiration rates, blood pressure, PaO2, PaCO2, and pH at begining, and at 10 and 60 minutes after starting the protocol. RESULTS: At 10 minutes, the patients in the bilevel positive pressure ventilation group had the highest PaO2 and the lowest respiration rates; the patients in the O2 group had the highest PaCO2 and the lowest pH (p<0.05). Four patients in the O2 group, 3 patients in the continuous positive pressure group, and none in the bilevel positive pressure ventilation group were intubated (p<0.05). CONCLUSION: Noninvasive bilevel positive pressure ventilation was effective in the treatment of acute cardiogenic pulmonary edema, accelerated the recovery of vital signs and blood gas data, and avoided intubation.

Hypertension and clustering of cardiovascular risk factors in a community in Southeast Brazil: the Bambuí Health and Ageing Study

OBJECTIVE - A population-based prospective study was analysed to: a) determine the prevalence of hypertension; b) investigate the clustering of other cardiovascular risk factors and c) verify whether older differed from younger adults in the pattern of clustering. METHODS - The data comprised a representative sample of the population of Bambuí, Brazil. Multiple logistic regression was used to investigate the independent association between hypertension and selected factors. RESULTS - A total of 820 younger adults (82.5%) and 1494 older adults (85.9%) participated in this study. The overall prevalence of hypertension was 24.8% (SE=1.4 %), being higher in women (26.9±1.5%) than in men (22.0± 1.7%) (p=0.033). Hypertension was positively and significantly associated with physical inactivity, overweight, hypercholesterolemia hyperglycemia and hypertriglyceridemia. The coexistence of hypertension with 4 or more of these risk factors occurred 6 times more than expected by chance, after adjusting for age and sex (OR=6.3; 95%CI: 3.4-11.9). The pattern of risk factor clustering in hypertensive individuals differed with age. CONCLUSION - Our results reinforce the need to increase detection and treatment of hypertension and to approach patients' global risk profiles.

Fibrilação atrial e demência: resultados do São Paulo ageing & health study

FUNDAMENTO: A fibrilação atrial é um fator de risco controverso para demência. OBJETIVO: O objetivo deste estudo é avaliar a associação entre fibrilação atrial e demência em participantes do São Paulo Ageing & Health. MÉTODOS: O São Paulo Ageing & Health é um estudo transversal, de base populacional, de idosos residentes em um uma região de baixa renda da cidade de São Paulo, Brasil. Diagnóstico de demência foi realizado de acordo com o protocolo do grupo 10/66, com base em critérios do Manual de Diagnóstico e Estatística das Perturbações Mentais (DSM-IV). O diagnóstico de fibrilação atrial foi feito por eletrocardiograma de 12 derivações, avaliado por dois cardiologistas. Dados demográficos e de fatores de risco cardiovasculares também foram obtidos. RESULTADOS: A demência foi diagnosticada em 66 (4,3%) e fibrilação atrial em 36 (2,4%) de 1.524 participantes com um eletrocardiograma válido. A razão de chances bruta para demência em participantes com fibrilação atrial foi 2,8 (intervalo de confiança [IC] 95%: 1,0-8,1; p = 0,06) em comparação com indivíduos sem fibrilação atrial. Relação positiva foi encontrada em mulheres (RC 4,2; IC 95%: 1,2-15,1; p = 0,03). Após ajuste para idade, no entanto, essa associação tornou-se não significativa (RC 2,2, IC 95%: 0,6-8,9; p = 0,26). CONCLUSÃO: Não houve associação independente entre a fibrilação atrial e demência nessa amostra. A prevalência da fibrilação atrial pode ser baixa nesta população em virtude da mortalidade cardiovascular prematura.

Growth of positive words and lower bounds of the growth rate for Thompson's group (F)p

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Diagnostic d'embolie pulmonaire: problématique résiduelle des D-dimères faussement positifs [The unresolved issue of false-positive D-dimer results in the diagnostic workup of pulmonary embolism].

The unresolved issue of false-positive D-dimer results in the diagnostic workup of pulmonary embolism Pulmonary embolism (PE) remains a difficult diagnosis as it lacks specific symptoms and clinical signs. After the determination of the pretest PE probability by a validated clinical score, D-dimers (DD) is the initial blood test in the majority of patients whose probability is low or intermediate. The low specificity of DD results in a high number of false-positives that then require thoracic angio-CT. A new clinical decision rule, called the Pulmonary Embolism Rule-out criteria (PERC), identifies patients at such low risk that PE can be safely ruled-out without a DD test. Its safety has been confirmed in US emergency departments, but retrospective European studies showed that it would lead to 5-7% of undiagnosed PE. Alternative strategies are needed to reduce the proportion of false-positive DD results.

Elements of algebraic geometry and the positive theory of partially commutative groups

The first main result of the paper is a criterion for a partially commutative group G to be a domain. It allows us to reduce the study of algebraic sets over G to the study of irreducible algebraic sets, and reduce the elementary theory of G (of a coordinate group over G) to the elementary theories of the direct factors of G (to the elementary theory of coordinate groups of irreducible algebraic sets). Then we establish normal forms for quantifier-free formulas over a non-abelian directly indecomposable partially commutative group H. Analogously to the case of free groups, we introduce the notion of a generalised equation and prove that the positive theory of H has quantifier elimination and that arbitrary first-order formulas lift from H to H * F, where F is a free group of finite rank. As a consequence, the positive theory of an arbitrary partially commutative group is decidable.

A comparison of results from MRIO and interregional computable general equilibrium (CGE) analyses of the impacts of a positive demand shock on the ‘CO2 trade balance’ between Scotland and the rest of the UK

In previous work we have applied the environmental multi-region input-output (MRIO) method proposed by Turner et al (2007) to examine the ‘CO2 trade balance’ between Scotland and the Rest of the UK. In McGregor et al (2008) we construct an interregional economy-environment input-output (IO) and social accounting matrix (SAM) framework that allows us to investigate methods of attributing responsibility for pollution generation in the UK at the regional level. This facilitates analysis of the nature and significance of environmental spillovers and the existence of an environmental ‘trade balance’ between regions. While the existence of significant data problems mean that the quantitative results of this study should be regarded as provisional, we argue that the use of such a framework allows us to begin to consider questions such as the extent to which a devolved authority like the Scottish Parliament can and should be responsible for contributing to national targets for reductions in emissions levels (e.g. the UK commitment to the Kyoto Protocol) when it is limited in the way it can control emissions, particularly with respect to changes in demand elsewhere in the UK. However, while such analysis is useful in terms of accounting for pollution flows in the single time period that the accounts relate to, it is limited when the focus is on modelling the impacts of any marginal change in activity. This is because a conventional demand-driven IO model assumes an entirely passive supply-side in the economy (i.e. all supply is infinitely elastic) and is further restricted by the assumption of universal Leontief (fixed proportions) technology implied by the use of the A and multiplier matrices. In this paper we argue that where analysis of marginal changes in activity is required, a more flexible interregional computable general equilibrium approach that models behavioural relationships in a more realistic and theory-consistent manner, is more appropriate and informative. To illustrate our analysis, we compare the results of introducing a positive demand stimulus in the UK economy using both IO and CGE interregional models of Scotland and the rest of the UK. In the case of the latter, we demonstrate how more theory consistent modelling of both demand and supply side behaviour at the regional and national levels affect model results, including the impact on the interregional CO2 ‘trade balance’.