Melting of polymer blends in single-screw extrusion : an experimental study

Melting is a major step in plasticating single screw extrusion, but most of the existing phenomenological know how was gathered by performing Maddock-type experiments with homopolymers. Given the current widespread industrial use of polymer blends, it is worth determining whether the same mechanisms and mathematical models apply, or whether different sequences develop. This work reports the results of Maddock-type experiments using a PA6/PP blend, both in its immiscible and compatibilized varieties. A melting mechanism combining the features of the classical Tadmor mechanism and of the dispersed melting mechanism, also previously reported in the literature, was observed.The authors are grateful to Portuguese Fundacao para a Ciencia e Tecnologia for supporting this work under grant SFRH/BD/19997/2004 and to DSM, the Netherlands, for supplying PA6

The associations of use of social network sites with perceived social support and loneliness

Research shows that use of social network sites is associated with loneliness and this may be amplified in tertiary students by their transition from home life, especially if they struggle to integrate with peers. The buffering effects of social support may offer a solution and the online dimension may offer a suitable outlet for lonely and isolated students. In this study, N = 111 university students, aged 18-40, completed a frequency assessment of Instagram and WhatsApp, the Spanish version of the UCLA loneliness scale and the Multidimensional Scale of Social Support in an online survey. The statistical analysis was completed by Structural Equation Modeling using AMOS 25.0. The construct validity of social network sites was established by good factor loadings for WhatsApp and Instagram, but Facebook was excluded as it did not load adequately on to the latent measurement model, in keeping with the diminishing trend for Facebook use in young students. Loneliness emerged as pivotal in a mediation model, and online social support from friends/significant others, emerged as salient in the predictive model in contrast to family. However, these associations may not have the same advantageous weight for mature students given the observed negative associations with age. Results may have implications for policy and planning through highlighting the psychological variables that are operative in the dynamics of integration, retention, and adjustment to tertiary level experience

Whole Exome Sequence Analysis Provides Novel Insights into the Genetic Framework of Childhood-Onset Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) describes a rare, progressive vascular disease caused by the obstruction of pulmonary arterioles, typically resulting in right heart failure. Whilst PAH most often manifests in adulthood, paediatric disease is considered to be a distinct entity with increased morbidity and often an unexplained resistance to current therapies. Recent genetic studies have substantially increased our understanding of PAH pathogenesis, providing opportunities for molecular diagnosis and presymptomatic genetic testing in families. However, the genetic architecture of childhood-onset PAH remains relatively poorly characterised. We sought to investigate a previously unsolved paediatric cohort (n = 18) using whole exome sequencing to improve the molecular diagnosis of childhood-onset PAH. Through a targeted investigation of 26 candidate genes, we applied a rigorous variant filtering methodology to enrich for rare, likely pathogenic variants. This analysis led to the detection of novel PAH risk alleles in five genes, including the first identification of a heterozygous ATP13A3 mutation in childhood-onset disease. In addition, we provide the first independent validation of BMP10 and PDGFD as genetic risk factors for PAH. These data provide a molecular diagnosis in 28% of paediatric cases, reflecting the increased genetic burden in childhood-onset disease and highlighting the importance of next-generation sequencing approaches to diagnostic surveillance

Haploinsufficiency of the NOTCH1 Receptor as a Cause of Adams-Oliver Syndrome With Variable Cardiac Anomalies.

BACKGROUND: Adams-Oliver syndrome (AOS) is a rare disorder characterized by congenital limb defects and scalp cutis aplasia. In a proportion of cases, notable cardiac involvement is also apparent. Despite recent advances in the understanding of the genetic basis of AOS, for the majority of affected subjects, the underlying molecular defect remains unresolved. This study aimed to identify novel genetic determinants of AOS. METHODS AND RESULTS: Whole-exome sequencing was performed for 12 probands, each with a clinical diagnosis of AOS. Analyses led to the identification of novel heterozygous truncating NOTCH1 mutations (c.1649dupA and c.6049_6050delTC) in 2 kindreds in which AOS was segregating as an autosomal dominant trait. Screening a cohort of 52 unrelated AOS subjects, we detected 8 additional unique NOTCH1 mutations, including 3 de novo amino acid substitutions, all within the ligand-binding domain. Congenital heart anomalies were noted in 47% (8/17) of NOTCH1-positive probands and affected family members. In leukocyte-derived RNA from subjects harboring NOTCH1 extracellular domain mutations, we observed significant reduction of NOTCH1 expression, suggesting instability and degradation of mutant mRNA transcripts by the cellular machinery. Transient transfection of mutagenized NOTCH1 missense constructs also revealed significant reduction in gene expression. Mutant NOTCH1 expression was associated with downregulation of the Notch target genes HEY1 and HES1, indicating that NOTCH1-related AOS arises through dysregulation of the Notch signaling pathway. CONCLUSIONS: These findings highlight a key role for NOTCH1 across a range of developmental anomalies that include cardiac defects and implicate NOTCH1 haploinsufficiency as a likely molecular mechanism for this group of disorders

Trabalho educativo do enfermeiro na Estratégia Saúde da Família: dificuldades e perspectivas de mudanças

Este estudo objetivou conhecer as dificuldades e perspectivas de mudanças que os enfermeiros identificam no desenvolvimento das ações educativas na Estratégia Saúde da Família (ESF). Trata-se de uma pesquisa qualitativa descritivo-exploratória. Os dados foram coletados junto a 20 enfermeiros que atuam na ESF, no âmbito da 10ª Regional de Saúde do Paraná, por meio de entrevistas semiestruturadas, no mês de abril de 2010, as quais foram submetidas à análise de conteúdo. Os resultados demonstraram que os enfermeiros enfrentam dificuldades no desenvolvimento da educação em saúde junto aos usuários, à equipe, aos gestores e quanto à falta de recursos físicos, materiais e financeiros. Mas, a partir das dificuldades sentidas, buscam alternativas diversificadas para superá-las e sugerem modificações visando à melhoria na atenção primária à saúde da população, principalmente, no que tange ao trabalho educativo

Using simulation to interpret a discrete time survival model in a complex biological system: fertility and lameness in dairy cows

The ever-growing volume of data routinely collected and stored in everyday life presents researchers with a number of opportunities to gain insight and make predictions. This study aimed to demonstrate the usefulness in a specific clinical context of a simulation-based technique called probabilistic sensitivity analysis (PSA) in interpreting the results of a discrete time survival model based on a large dataset of routinely collected dairy herd management data. Data from 12,515 dairy cows (from 39 herds) were used to construct a multilevel discrete time survival model in which the outcome was the probability of a cow becoming pregnant during a given two day period of risk, and presence or absence of a recorded lameness event during various time frames relative to the risk period amongst the potential explanatory variables. A separate simulation model was then constructed to evaluate the wider clinical implications of the model results (i.e. the potential for a herd’s incidence rate of lameness to influence its overall reproductive performance) using PSA. Although the discrete time survival analysis revealed some relatively large associations between lameness events and risk of pregnancy (for example, occurrence of a lameness case within 14 days of a risk period was associated with a 25% reduction in the risk of the cow becoming pregnant during that risk period), PSA revealed that, when viewed in the context of a realistic clinical situation, a herd’s lameness incidence rate is highly unlikely to influence its overall reproductive performance to a meaningful extent in the vast majority of situations. Construction of a simulation model within a PSA framework proved to be a very useful additional step to aid contextualisation of the results from a discrete time survival model, especially where the research is designed to guide on-farm management decisions at population (i.e. herd) rather than individual level