Suchergebnisse

We have developed a teaching learning sequence on friction based on a preliminary study involving three dimensions: an analysis of didactic research on the topic, an overview of usual approaches, and a critical analysis of the subject, considered also in its historical development. We found that mostly the usual presentations do not take into account the complexity of friction as it emerges from scientific research, may reinforce some inaccurate students' conceptions and favour a limited vision of friction phenomena. The TLS we propose begins by considering a wide range of friction phenomena to favour an initial motivation and a broader view of the topic and then develops a path of interrelated observations, experiments and theoretical aspects. It proposes the use of structural models, involving visual representations and stimulating intuition, aimed at helping students build mental models of friction mechanisms. To facilitate the reproducibility in school contexts, the sequence is designed as an open source structure, with a core of contents, conceptual correlations and methodological choices, and a cloud of elements that can be re-designed by teachers. The sequence has been tested in teacher education and in upper secondary school, and has shown positive results in overcoming student difficulties and stimulating richer reasoning based on the structural models we suggested. The proposed path has modified the teachers' view of the topic, producing a motivation to change their traditional presentations. The open structure of the sequence has facilitated its implementation by teachers in school in coherence with the rationale of the proposal.

BackgroundHIV can spread into the central nervous system (CNS) early in the course of infection and this turns into intrathecal inflammation and neuronal damage. We aimed to investigate clinical and immunological parameters associated with elevated CSF VL in HIV‐infected ART‐naïve patients.Materials and MethodsHIV+ ART‐naïve patients underwent a comprehensive battery of neurocognitive (NC) tests and lumbar puncture (LP) for CSF HIV‐RNA detection. Plasma HIV‐RNA and peripheral T‐cell immune‐phenotypes (CD38/CD45RA/CD45R0/CD127 on CD4/CD8) were also assessed (flow cytometry). High‐CSF HIV RNA was defined as≥10000cp/mL (H‐CSF), while CSF HIV RNA<10000cp/mL characterized low VL patients (L‐CSF). Chi‐square and Mann‐Whitney tests were used. Parameters independently associated with CSF VL were explored by multivariate regression.ResultsA total of 131 patients were retrospectively enrolled. Forty‐two patients (32%) had CSF VL >10000 cp/mL.Table 1 shows the features of H‐ versus L‐CSF patients. Compared to L‐CSF patients, H‐CSF patients displayed lower current CD4+%, lower CD4/CD8 ratio and higher CD8%. No differences in NC tests performance were observed between groups (p=0.6). Regarding T‐cell immuno‐phenotypes, H‐CSF patients displayed a higher proportion of CD45R0+CD38+CD8+ (11 vs 7%, p=0.02) and lower expression of CD45RA+CD8+ % (16 vs 20%, p=0.007), in comparison to L‐CSF patients. In multivariate analysis CD45RA+CD8+ T‐cells % (OR 0.917, CI 95% 0.852–0.987, p=0.002) was associated with H‐CSF, even after adjustment for plasma VL, CD8 and CD4 count. Globally, in univariate CSF VL inversely correlated with CD45RA+CD8+ % (r=−0.223, p=0.0217) and CD127+CD4+ % (r= −0.204, p= 0.0225), while a positive association was found between CSF and plasma VL (r=0.303, p=0.0004) and CD8 % (r=0.211, p=0.016). In multivariate linear regression, in addition to positive association between plasma and CSF VL (β: 0.212, 95% CI 0.02–0.41, p=0.032), also CD45RA+CD8+ % were confirmed inversely associated to CSF VL (β: 0.21, 95% CI −0.5 to −0.002, p=0.036), adjusting for CD4/CD8 and CD4CD127 %.ConclusionsWe hereby describe a 32% prevalence of H‐CSF in a cohort of HIV+ ART‐naïve patients. Subjects with high‐CSF viral replication are mostly with higher systemic immune activation, in particular the percentage of naïve CD8 T‐cell is positively associated with CSF VL, irrespective of plasma VL. In HIV+ ART‐naïve patients, especially if featuring a hyperactivated T‐cell immune‐phenotype, lumbar puncture should be considered to further guide CNS‐targeted cART.