265 research outputs found
Inhibiting the Thermal Gelation of Copolymer Stabilized Nonaqueous Dispersions and the Synthesis of Full Color PMMA Particles
Polymeric particle dispersions have numerous potential applications; currently one of the most relevant is their use as inks in electrophoretic displays. These colloidal particles are synthesized from the appropriate monomer using nonaqueous dispersion (NAD) polymerization in a nonpolar solvent, which requires a stabilizer to control particle size and morphology. We have previously reported the facile synthesis of poly(methyl methacrylate)-block-poly(octadecyl acrylate) (PMMA-b-PODA) by atom transfer radical polymerization (ATRP), and its use in the NAD polymerization of MMA in hexane/dodecane solvent mixtures. Here we report the synthesis of monodisperse PMMA particles in dodecane following a standard “industrial” procedure using these PMMA-b-PODA stabilizers. However, it was observed that the particle suspensions solidified when they were left at temperatures below ?18 °C yet redispersed upon being heated. Differential scanning calorimetry, dynamic light scattering, and rheological studies demonstrated that this thermoresponsive behavior was due to a liquid–gel transition occurring at 17.5 °C as a consequence of the upper critical solution temperature of PODA in dodecane being traversed. Consequently, new copolymers were synthesized by ATRP with an ethylhexyl acrylate (EHA) co-monomer incorporated into the lyophilic (dodecane compatible) block. Dispersions stabilized by these PMMA-b-P(ODA-co-EHA) polymers with high EHA contents exhibited lower gelation temperatures because of the greater solvent compatibility with dodecane. The use of a PMMA65-b-(ODA10-co-EHA45) copolymer stabilizer (with the highest EHA content) gave PMMA dispersions that showed no gelation down to 4 °C and monodisperse cross-linked PMMA particles containing organic dyes (cyan, magenta, red, and black) giving colored particles across the size range of approximately 100–1300 nm
Common HLA Alleles Associated with Health, but Not with Facial Attractiveness
Three adaptive hypotheses have been proposed to explain the link between the human leucocyte antigen (HLA) genes, health measures and facial attractiveness: inbreeding avoidance, heterozygote advantage and frequency-dependent selection. This paper reports findings that support a new hypothesis relating HLA to health. We suggest a new method to quantify the level of heterozygosity. HLA heterozygosity did not significantly predict health measures in women, but allele frequency did. Women with more common HLA alleles reported fewer cold and flu bouts per year, fewer illnesses in the previous year and rated themselves healthier than women with rare alleles. To our knowledge, this is the first study to show a positive correlation between HLA allele frequency and general health measures. We propose that certain common HLA alleles confer resistance to prevalent pathogens. Nevertheless, neither HLA heterozygosity nor allele frequency significantly predicted how healthy or attractive men rated the female volunteers. Three non-mutually exclusive explanations are put forward to explain this finding
Facial-based ethnic recognition: insights from two closely related by ethnically distinct groups
Sherpa Romeo blue journal; open accessPrevious studies on facial recognition have considered widely
separated populations, both geographically and culturally, making
it hard to disentangle effects of familiarity with an ability to identify
ethnic groups per se.We used data from a highly intermixed population
of African peoples from South Africa to test whether individuals
from nine different ethnic groups could correctly differentiate between facial images of two of these, the Tswana and Pedi. Individuals
could not assign ethnicity better than expected by chance, and
there was no significant difference between genders in accuracy of
assignment. Interestingly, we observed a trend that individuals of
mixed ethnic origin were better at assigning ethnicity to Pedi and
Tswanas, than individuals from less mixed backgrounds. This
result supports the hypothesis that ethnic recognition is based on
the visual expertise gained with exposure to different ethnic
groups
Individual-level movement bias leads to the formation of higher-order social structure in a mobile group of baboons
Sherpa Romeo green journal. Open access article. Creative Commons Attribution 4.0 International LIcense (CC BY 4.0) applies.In mobile social groups, influence patterns driving group movement can vary between democratic and despotic. The arrival at any single pattern of influence is thought to be underpinned by both environmental factors and group composition. To identify the specific patterns of influence driving travel decision-making in a chacma baboon troop, we used spatially explicit data to extract patterns of individual movement bias. We scaled these estimates of individual-level bias to the level of the group by constructing an influence network and assessing its emergent structural properties. Our results indicate that there is heterogeneity in movement bias: individual animals respond consistently to particular group members, and higher-ranking animals are more likely to influence the movement of others. This heterogeneity resulted in a group-level network structure that consisted of a single core and two outer shells. Here, the presence of a core suggests thatasetofhighlyinterdependentanimalsdroveroutinegroup movements. These results suggest that heterogeneity at the individual level can lead to group-level influence structures, and that movement patterns in mobile social groups can add to the exploration of both how these structures develop (i.e. mechanistic aspects) and what consequences they have for individual- and group-level outcomes (i.e. functional aspects).Ye
Ontogenetic scaling of fore- and hind limb posture in wild chacma baboons (Papio hamadryas ursinus)
Sherpa Romeo green journal: open accessLarge-scale interspecific studies of mammals ranging between 0.04–280 kg have shown that larger animals walk with more
extended limb joints. Within a taxon or clade, however, the relationship between body size and joint posture is less
straightforward. Factors that may affect the lack of congruence between broad and narrow phylogenetic analyses of limb
kinematics include limited sampling of (1) ranges of body size, and/or (2) numbers of individuals. Unfortunately, both issues
are inherent in laboratory-based or zoo locomotion research. In this study, we examined the relationship between body
mass and elbow and knee joint angles (our proxies of fore- and hind limb posture, respectively) in a cross-sectional
ontogenetic sample of wild chacma baboons (Papio hamadryas ursinus) habituated in the De Hoop Nature Reserve, South
Africa. Videos were obtained from 33 individuals of known age (12 to $108 months) and body mass (2–29.5 kg) during
walking trials. Results show that older, heavier baboons walk with significantly more extended knee joints but not elbow
joints. This pattern is consistent when examining only males, but not within the female sample. Heavier, older baboons also
display significantly less variation in their hind limb posture compared to lighter, young animals. Thus, within this
ontogenetic sample of a single primate species spanning an order of magnitude in body mass, hind limb posture exhibited
a postural scaling phenomenon while the forelimbs did not. These findings may further help explain 1) why younger
mammals (including baboons) tend to have relatively stronger bones than adults, and 2) why humeri appear relatively
weaker than femora (in at least baboons). Finally, this study demonstrates how field-acquired kinematics can help answer
fundamental biomechanical questions usually addressed only in animal gait laboratories.Ye
Does gender matter? A cross-national investigation of primary class-room discipline.
© 2018 Informa UK Limited, trading as Taylor & Francis GroupFewer than 15% of primary school teachers in both Germany and the UK are male. With the on-going international debate about educational performance highlighting the widening gender achievement gap between girl and boy pupils, the demand for more male teachers has become prevalent in educational discourse. Concerns have frequently been raised about the underachievement of boys, with claims that the lack of male ‘role models’ in schools has an adverse effect on boys’ academic motivation and engagement. Although previous research has examined ‘teaching’ as institutional talk, men’s linguistic behaviour in the classroom remains largely ignored, especially in regard to enacting discipline. Using empirical spoken data collected from four primary school classrooms in both the UK and in Germany, this paper examines the linguistic discipline strategies of eight male and eight female teachers using Interactional Sociolinguistics to address the question, does teacher gender matter?Peer reviewedFinal Accepted Versio
Population ecology of vervet monkeys in a high latitude, semi-arid riparian woodland
Sherpa Romeo green journal: open accessNarrow riparian woodlands along non-perennial streams have made it possible for vervet
monkeys to penetrate the semi-arid karoo ecosystem of South Africa, whilst artificial water
points have more recently allowed these populations to colonize much more marginal habitat
away from natural water sources. In order to better understand the sequelae of life in these
narrow, linear woodlands for historically ‘natural’ populations and to test the prediction that
they are ecologically stressed, we determined the size of troops in relation to their reliance
on natural and artificial water sources and collected detailed data from two river-centred
troops on activity, diet and ranging behaviour over an annual cycle. In comparison to other
populations, our data indicate that river-centred troops in the karoo were distinctive primarily
both for their large group sizes and, consequently, their large adult cohorts, and in the extent of
home range overlap in what is regarded as a territorial species. Whilst large group size carried
the corollary of increased day journey length and longer estimated interbirth intervals, there
was little other indication of the effects of ecological stress on factors such as body weight
and foraging effort. We argue that this was a consequence of the high density of Acacia karroo,
which accounted for a third of annual foraging effort in what was a relatively depauperate
floristic habitat. We ascribed the large group size and home range overlap to constraints on
group fission.
Conservation implications: The distribution of group sizes, sampled appropriately across
habitats within a conservation area, will be of more relevance to management than average
values, which may be nothing more than a statistical artefact, especially when troop sizes are
bimodally distributed.Ye
Developing inclusive practice in Scotland: the National Framework for Inclusion
Introduction and context Developing the Framework Principles of the revised National Framework for Inclusion Reflections on the collaborative processes in developing the Framework Using the Framework Conclusion References Full Article Figures & data References Citations Metrics Reprints & Permissions PDF Abstract This paper reports on the collaborative development of a ‘National Framework for Inclusion’ under the auspices of the Scottish Teacher Education Committee by a working party representing each of the Scottish Universities providing initial teacher education. Recent research, international legislation and Scottish education policy have refocused the notion of ‘special educational needs’ based on ideas of individual deficit to support and provision for all learners. As teachers are therefore charged with responsibility for an increasingly diverse population of learners, the National Framework of Inclusion was developed to support both pre-service and qualified teachers to work inclusively to provide fair and meaningful experiences for all learners. The paper examines the underpinning principles of the Framework, describes the collaborative process of its development and provides one innovative example of its use
Investigating hyper-vigilance for social threat of lonely children
The hypothesis that lonely children show hypervigilance for social threat was examined in a series of three studies that employed different methods including advanced eye-tracking technology. Hypervigilance for social threat was operationalized as hostility to ambiguously motivated social exclusion in a variation of the hostile attribution paradigm (Study 1), scores on the Children’s Rejection-Sensitivity Questionnaire (Study 2), and visual attention to socially rejecting stimuli (Study 3). The participants were 185 children (11 years-7 months to 12 years-6 months), 248 children (9 years-4 months to 11 years-8 months) and 140 children (8 years-10 months to 12 years-10 months) in the three studies, respectively. Regression analyses showed that, with depressive symptoms covaried, there were quadratic relations between loneliness and these different measures of hypervigilance to social threat. As hypothesized, only children in the upper range of loneliness demonstrated elevated hostility to ambiguously motivated social exclusion, higher scores on the rejection sensitivity questionnaire, and disengagement difficulties when viewing socially rejecting stimuli. We found that very lonely children are hypersensitive to social threat
Phocine Distemper Virus in Seals, East Coast, United States, 2006
: Phocine Distemper Virus in Seal
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