Chemical Competition between Microscopic Stages of Macrocystis pyrifera and Five Native Kelp Species: Does Giant Kelp Always Lose?

The giant kelp Macrocystis pyrifera is often considered competitively dominant to other kelp species due to its high productivity. However, on the microscopic level, previous studies found that Macrocystis can be inferior to other kelp species through microscopic interspecies chemical competition. Recruitment failure can be caused by neighboring kelps because there is no species specificity in the stereochemistry of the signaling chemical used during reproduction to initiate spermatozoid release; therefore, Macrocystis spermatozoid release is pre-empted by that of its competitors. To date, this interaction has been tested between Macrocystis and only one other kelp taxon, Pterygophora. To test whether Macrocystis is always chemically outcompeted microscopically, I investigated the competitive outcome, by tracking sporophyte production, between Macrocystis and five native kelps using laboratory studies. Tests with Pterygophora californica and Ecklonia arborea showed asymmetric results indicating that Macrocystis was the inferior kelp. Studies using Alaria marginata and Egregia menziesii found symmetric results where both competing species did poorly in the presence of Macrocystis. Lastly, when Macrocystis was settled with Postelsia palmaeformis, there was no significant difference in sporophyte production between polycultures and monocultures for either species. These results indicate that the competitively superior species will vary depending on the specific species interaction

Comparison of academic performance of twins and singletons in adolescence : follow-up study

Objectives To determine whether twins in recent cohorts show similar academic performance in adolescence to singletons and to test the effect of birth weight on academic performance in twins and singletons. Design Follow-up study. Setting Denmark. Participants All twins (n = 3411) and a 5% random sample of singletons (n = 7796) born in Denmark during 1986-8. Main outcome measures Test scores in ninth grade (age 15 or 16), birth weight, gestational age at birth, parents’ age, and parents’ education. Results Ninth grade test scores were normally distributed, with almost identical mean and standard deviations for twins and singletons (8.02 v 8.02 and 1.05 v 1.06) despite the twins weighing on average 908 g (95% confidence interval 886 to 930 g) less than the singletons at birth. Controlling for birth weight, gestational age at birth, age at test, and parents’ age and education confirmed the similarity of test scores for twins and singletons (difference 0.04, 95% confidence interval − 0.03 to 0.10). A significant, positive association between test score and birth weight was observed in both twins and singletons, but the size of the effect was small: 0.06-0.12 standard deviations for every kilogram increase in birth weight. Conclusions Although older cohorts of twins have been found to have lower mean IQ scores than singletons, twins in recent Danish cohorts show similar academic performance in adolescence to that of singletons. Birth weight has a minimal effect on academic performance in recent cohorts; for twins this effect is best judged relative to what is a normal birth weight for twins and not for singletons

Homology and Cohomology of E-infinity Ring Spectra

Every homology or cohomology theory on a category of E-infinity ring spectra is Topological Andre-Quillen homology or cohomology with appropriate coefficients. Analogous results hold for the category of A-infinity ring spectra and for categories of algebras over many other operads

Degree of disability among female healthcare workers who are overweight or obese

Background: The prevalence of overweight and obesity is increasing worldwide. Research has clarified that being overweight or obese can lead to disability in everyday life. Aim: The present study explores the association between the degrees of experienced disability in Danish female healthcare workers with a Body Mass Index (BMI) classified as being overweight or obese, compared to female healthcare workers classified as being normal weight. Material and methods: 67 females with a mean age of 49.5 years and a mean BMI of 27.5 kg/m2 completed a questionnaire exploring the degree of experienced disability in their everyday lives. Results: The degree of disability in the following activities were significantly higher among females who were obese compared to females who were normal weight; Walking up/down two or more staircases, Pedicure, Dressing the lower body and Exercising outside the home. No statistical differences were found between the females that were overweight and the females that were normal weight. Conclusion: Female healthcare workers who are obese experience a higher degree of disability, than females with a normal weight. Offering an occupational therapy intervention to reduce disability and facilitate participation in everyday life could be relevant

Embodied Practices of Prosthesis

While the prosthesis is often thought of as a technology or an artefact used to ‘fix’ or make ‘whole’ a disabled body, it has also become an important figuration and metaphor for thinking about disabled embodiment as an emblematic manifestation of bodily difference and mobility. Furthermore, the ambiguity and broadness of prosthesis as an object and a concept, as well as its potential as a theoretical and analytical thinking tool, show up in widely different areas of popular culture, art and academic scholarship. In this article, we explore the opportunities of the ways in which prosthesis might be a helpful and productive fi gure in relation to framing, analyzing and understanding certain healthcare-related practices that are not traditionally associated with disability. Our aim is to suggest new ways of building onto the idea of the performative value of the prosthetic fi gure and its logics as a continuum through which very different forms of embodied practices could be meaningfully understood and analyzed. Thus, we argue that the logic of the prosthesis can be helpful in uncovering tensions related to idealistic and dominant ideas about health and embodiment. First, we engage with the theoretical discussions from cultural studies, including critical disability studies, in which we broaden the scope of the concept of prosthesis. Second, we introduce and discuss two illustrative case examples in the form of dance therapeutic practices for people with Parkinson’s disease and group therapeutic practices in male-friendly spaces. In doing so, we seek to raise new questions about the ongoing cultivation of bodily and health-related interventions through the lens of the prosthetic spectrum, which we have labelled embodied practices of prosthesis

Trans-kingdom cross-talk:small RNAs on the move

This review focuses on the mobility of small RNA (sRNA) molecules from the perspective of trans-kingdom gene silencing. Mobility of sRNA molecules within organisms is a well-known phenomenon, facilitating gene silencing between cells and tissues. sRNA signals are also transmitted between organisms of the same species and of different species. Remarkably, in recent years many examples of RNA-signal exchange have been described to occur between organisms of different kingdoms. These examples are predominantly found in interactions between hosts and their pathogens, parasites, and symbionts. However, they may only represent the tip of the iceberg, since the emerging picture suggests that organisms in biological niches commonly exchange RNA-silencing signals. In this case, we need to take this into account fully to understand how a given biological equilibrium is obtained. Despite many observations of trans-kingdom RNA signal transfer, several mechanistic aspects of these signals remain unknown. Such RNA signal transfer is already being exploited for practical purposes, though. Pathogen genes can be silenced by plant-produced sRNAs designed to affect these genes. This is also known as Host-Induced Genes Silencing (HIGS), and it has the potential to become an important disease-control method in the future