Overstating the evidence - double counting in meta-analysis and related problems

Background: The problem of missing studies in meta-analysis has received much attention. Less attention has been paid to the more serious problem of double counting of evidence. Methods: Various problems in overstating the precision of results from meta-analyses are described and illustrated with examples, including papers from leading medical journals. These problems include, but are not limited to, simple double-counting of the same studies, double counting of some aspects of the studies, inappropriate imputation of results, and assigning spurious precision to individual studies. Results: Some suggestions are made as to how the quality and reliability of meta-analysis can be improved. It is proposed that the key to quality in meta-analysis lies in the results being transparent and checkable. Conclusions: Existing quality check lists for meta-analysis do little to encourage an appropriate attitude to combining evidence and to statistical analysis. Journals and other relevant organisations should encourage authors to make data available and make methods explicit. They should also act promptly to withdraw meta-analyses when mistakes are found

The impact of sexual education and socialization on sexual satisfaction, attitudes, and self-efficacy

This study examined the relation between school-based sexual education and parental messages about sex received in adolescence, and sexual attitudes and experiences in young adulthood. Participants—99 Canadian undergraduate students aged 17–25 years—reported that their sexual education largely focused on traditional topics (e.g., negative health outcomes, physiology, etc.), while social and emotional topics were less likely to be formally covered. Parental sexual socialization that was more comfortable and accepting of teen sexuality was related to more permissive sexual attitudes in young adults, but was unrelated to self-efficacy or sexual satisfaction. When all variables were examined using hierarchical regression, sexual education and parental socialization did not predict sexual satisfaction. However, mediation analysis revealed an indirect effect of sexual self-efficacy on the relation between sexual education and sexual satisfaction. More comprehensive and higher-quality sexual education increased sexual self-efficacy, which was then related to higher sexual satisfaction beyond the role of gender and relationship status. This provides insight into the mechanism by which sexual education in Canada may impact sexual satisfaction. The influence of parental socialization and school-based sexual education are apparent and complementary. Both sources of information and values (parents/school) offered benefits for young adults’ positive sexual attitudes, but school-based education appears to be key. How sexual education is delivered (e.g., if teachers are knowledgeable and comfortable discussing topics) may be even more important than the content itself. These findings suggest that prioritizing teacher training to improve their comfort with delivery of sexual education programming would improve adolescents and young adults’ sexual lives

Ellipsoidal analysis of coordination polyhedra

The idea of the coordination polyhedron is essential to understanding chemical structure. Simple polyhedra in crystalline compounds are often deformed due to structural complexity or electronic instabilities so distortion analysis methods are useful. Here we demonstrate that analysis of the minimum bounding ellipsoid of a coordination polyhedron provides a general method for studying distortion, yielding parameters that are sensitive to various orders in metal oxide examples. Ellipsoidal analysis leads to discovery of a general switching of polyhedral distortions at symmetry-disallowed transitions in perovskites that may evidence underlying coordination bistability, and reveals a weak off-centre ‘d(5) effect' for Fe(3+) ions that could be exploited in multiferroics. Separating electronic distortions from intrinsic deformations within the low temperature superstructure of magnetite provides new insights into the charge and trimeron orders. Ellipsoidal analysis can be useful for exploring local structure in many materials such as coordination complexes and frameworks, organometallics and organic molecules

Atomic-scale structure and properties of highly stable antiphase boundary defects in Fe3O4

The complex and intriguing properties of the ferrimagnetic half metal magnetite (Fe3O4) are of continuing fundamental interest as well as being important for practical applications in spintronics, magnetism, catalysis and medicine. There is considerable speculation concerning the role of the ubiquitous antiphase boundary (APB) defects in magnetite, however, direct information on their structure and properties has remained challenging to obtain. Here we combine predictive first principles modelling with high-resolution transmission electron microscopy to unambiguously determine the three-dimensional structure of APBs in magnetite. We demonstrate that APB defects on the {110} planes are unusually stable and induce antiferromagnetic coupling between adjacent domains providing an explanation for the magnetoresistance and reduced spin polarization often observed. We also demonstrate how the high stability of the {110} APB defects is connected to the existence of a metastable bulk phase of Fe3O4, which could be stabilized by strain in films or nanostructures

Hsp21potentiates antifungal drug tolerance in Candida albicans

Peer reviewedPublisher PD

Long range electronic phase separation in CaFe3O5

Electronic phase separation is an important feature of many correlated perovskite compounds but hasn’t been seen in other complex oxides with similar physical behaviour such as magnetite. Hong et al. find phase separation between a magnetite-like charge ordered phase and a charge averaged phase in CaFe3O5

Frustration wave order in iron(II) oxide spinels

Frustrated magnetic materials provide a great laboratory to study the interplay between classical order and quantum fluctuations. The authors study the frustrated magnetic ground states of two Fe spinel oxides showing that the frustration is a fluctuating characteristic that manifests itself as a “frustration wave