1,405 research outputs found
First performance of the gems + gmos system. Part1. Imaging
During the commissioning of the Gemini MCAO System (GeMS), we had the
opportunity to obtain data with the Gemini Multi-Object Spectrograph (GMOS),
the most utilised instrument at Gemini South Observatory, in March and May
2012. Several globular clusters were observed in imaging mode that allowed us
to study the performance of this new and untested combination. GMOS is a
visible instrument, hence pushing MCAO toward the visible.We report here on the
results with the GMOS instruments, derive photometric performance in term of
Full Width Half Maximum (FWHM) and throughput. In most of the cases, we
obtained an improvement factor of at least 2 against the natural seeing. This
result also depends on the Natural Guide Star constellation selected for the
observations and we then study the impact of the guide star selection on the
FWHM performance.We also derive a first astrometric analysis showing that the
GeMS+GMOS system provide an absolute astrometric precision better than 8mas and
a relative astrometric precision lower than 50 mas.Comment: 13 pages, 11 figures, accepted for publication in MNRAS on March 23rd
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Discrimination of Chiral Guests by Chiral Channels: Variable Temperature Studies by SXRD and Solid State 13C NMR of the Deoxycholic Acid Complexes of Camphorquinone and Endo-3-Bromocamphor
3a,12a-Dihydroxy-5b-cholan-24-oic acid (deoxycholic acid DCA) is able to discriminate between the R- and S-enantiomers of camphorquinone and endo-(1)-3-bromocamphor and select only the S-enantiomers from a racemic mixture. DCA forms novel well ordered 1:1 adducts with (1S)-(1)-camphorquinone and (1S)-endo-(-)-3-bromocamphor,
both of which have been characterized by single crystal X-ray diffraction SXRD). When DCA is cocrystallized with (RS)-camphorquinone and (RS)-endo-3-bromocamphor,1:1 adducts of the S-enantiomers are produced together with crystals of the
free racemic guest. In contrast, in the absence of (1S)-(1)-camphorquinone, DCA forms a 2:1 adduct with (1R)-(2)-camphorquinone. In this 2:1 adduct the guest is disordered
at ambient temperature and undergoes a phase change in the region 160–130 K similar to that observed for the ferrocene adduct, but with only partial ordering of the guest.
The SXRD structure of the low temperature form and the variable temperature 13C CP/MAS NMR are reported. Cocrystallizing DCA with (1R)-endo-(1)-3-bromocamphor gives
the free guest and a glassy solid
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Ecological theatre and the evolutionary game: how environmental and demographic factors determine payoffs in evolutionary games
In the standard approach to evolutionary games and replicator dynamics, differences in fitness can be interpreted as an excess from the mean Malthusian growth rate in the population. In the underlying reasoning, related to an analysis of "costs" and "benefits", there is a silent assumption that fitness can be described in some type of units. However, in most cases these units of measure are not explicitly specified. Then the question arises: are these theories testable? How can we measure "benefit" or "cost"? A natural language, useful for describing and justifying comparisons of strategic "cost" versus "benefits", is the terminology of demography, because the basic events that shape the outcome of natural selection are births and deaths. In this paper, we present the consequences of an explicit analysis of births and deaths in an evolutionary game theoretic framework. We will investigate different types of mortality pressures, their combinations and the possibility of trade-offs between mortality and fertility. We will show that within this new approach it is possible to model how strictly ecological factors such as density dependence and additive background fitness, which seem neutral in classical theory, can affect the outcomes of the game. We consider the example of the Hawk-Dove game, and show that when reformulated in terms of our new approach new details and new biological predictions are produced
Childhood and the politics of scale: Descaling children's geographies?
This is the post-print version of the final published paper that is available from the link below. Copyright @ 2008 SAGE Publications.The past decade has witnessed a resurgence of interest in the geographies of children's lives, and particularly in engaging the voices and activities of young people in geographical research. Much of this growing body of scholarship is characterized by a very parochial locus of interest — the neighbourhood, playground, shopping mall or journey to school. In this paper I explore some of the roots of children's geographies' preoccupation with the micro-scale and argue that it limits the relevance of research, both politically and to other areas of geography. In order to widen the scope of children's geographies, some scholars have engaged with developments in the theorization of scale. I present these arguments but also point to their limitations. As an alternative, I propose that the notion of a flat ontology might help overcome some difficulties around scalar thinking, and provide a useful means of conceptualizing sociospatiality in material and non-hierarchical terms. Bringing together flat ontology and work in children's geographies on embodied subjectivity, I argue that it is important to examine the nature and limits of children's spaces of perception and action. While these spaces are not simply `local', they seldom afford children opportunities to comment on, or intervene in, the events, processes and decisions that shape their own lives. The implications for the substance and method of children's geographies and for geographical work on scale are considered
Decreased neuroinflammation correlates to higher vagus nerve activity fluctuations in near-term ovine fetuses: a case for the afferent cholinergic anti-inflammatory pathway?
Motor Nucleus of Vagus---Location. Methods supplementary material: Neuroanatomical approach to locating vagal motor nucleus in fetal sheep brain (PDF 1716 kb
Beings in their own right? Exploring Children and young people's sibling and twin relationships in the Minority World
This paper examines the contributions that the sociological study of sibship and twinship in the Minority World can make to childhood studies. It argues that, in providing one forum within which to explore children and young people's social relationships, we can add to our understanding of children and young people's interdependence and develop a more nuanced understanding of agency. As emergent subjects, children, young people and adults are in a process of ‘becoming’. However, this does not mean that they can ‘become’ anything they choose to. The notion of negotiated interdependence (Punch 2002) is useful in helping us to grasp the contingent nature of children and young people's agency
Understanding children’s constructions of meanings about other children: implications for inclusiveeducation
This paper explores the factors that influence the way children construct meanings about other children, and especially those who seem to experience marginalisation, within school contexts. The research involved an ethnographic study in a primary school in Cyprus over a period of 5 months. Qualitative methods were used, particularly participant observations and interviews with children. Interpretation of the data suggests that children's perceptions about other children, and especially those who come to experience marginalisation, are influenced by the following factors: other children and the interactions between them; adults’ way of behaving in the school; the existing structures within the school; and the cultures of the school and the wider educational context. Even though the most powerful factor was viewed to be the adults’ influence, it was rather the interweaving between different factors that seemed to lead to the creation of particular meanings for other children. In the end, it is argued that children's voices should be seen as an essential element within the process of developing inclusive practices.<br/
Investigating child participation in the everyday talk of a teacher and children in a preparatory year
In early years research, policy and education, a democratic perspective that positions children as participants and citizens is increasingly emphasized. These ideas take seriously listening to children’s opinions and respecting children’s influence over their everyday affairs. While much political and social investment has been paid to the inclusion of participatory approaches little has been reported on the practical achievement of such an approach in the day to day of early childhood education within school settings. This paper investigates talk and interaction in the everyday activities of a teacher and children in an Australian preparatory class (for children age 4-6 years) to see how ideas of child participation are experienced. We use an interactional analytic approach to demonstrate how participatory methods are employed in practical ways to manage routine interactions. Analysis shows that whilst the teacher seeks the children’s opinion and involves them in decision-making, child participation is at times constrained by the context and institutional categories of “teacher” and “student” that are jointly produced in their talk. The paper highlights tensions that arise for teachers as they balance a pedagogical intent of “teaching” and the associated institutional expectations, with efforts to engage children in decision-making. Recommendations include adopting a variety of conversational styles when engaging with children; consideration of temporal concerns and the need to acknowledge the culture of the school
Conceptualisations of children’s wellbeing at school: the contribution of recognition theory
A large study in Australian schools aimed to elucidate understandings of ‘wellbeing’ and of factors in school life that contribute to it. Students and teachers understood wellbeing primarily, and holistically, in terms of interpersonal relationships, in contrast to policy documents which mainly focused on ‘problem areas’ such as mental health. The study also drew on recognition theory as developed by the social philosopher Axel Honneth. Results indicate that recognition theory may be useful in understanding wellbeing in schools, and that empirical research in schools may give rise to further questions regarding theory
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