24,598 research outputs found
Structure, bonding and morphology of hydrothermally synthesised xonotlite
The authors have systematically investigated the role of synthesis conditions upon the structure and morphology of xonotlite. Starting with a mechanochemically prepared, semicrystalline phase with Ca/Si=1, the authors have prepared a series of xonotlite samples hydrothermally, at temperatures between 200 and 250 degrees C. Analysis in each case was by X-ray photoelectron spectroscopy, environmental scanning electron microscopy and X-ray diffraction. The authors’ use of a much lower water/solid ratio has indirectly confirmed the ‘through solution’ mechanism of xonotlite formation, where silicate dissolution is a key precursor of xonotlite formation. Concerning the role of temperature, too low a temperature (~200 degrees C) fails to yield xonotlite or leads to increased number of structural defects in the silicate chains of xonotlite and too high a temperature (>250 degrees C) leads to degradation of the xonotlite structure, through leaching of interchain calcium. Synthesis duration meanwhile leads to increased silicate polymerisation due to diminishing of the defects in the silicate chains and more perfect crystal morphologies
Chromatin proteins and RNA are associated with DNA during all phases of mitosis.
Mitosis brings about major changes to chromosome and nuclear structure. We used recently developed proximity ligation assay-based techniques to investigate the association with DNA of chromatin-associated proteins and RNAs in Drosophila embryos during mitosis. All groups of tested proteins, histone-modifying and chromatin-remodeling proteins and methylated histones remained in close proximity to DNA during all phases of mitosis. We also found that RNA transcripts are associated with DNA during all stages of mitosis. Reduction of H3K27me3 levels or elimination of RNAs had no effect on the association of the components of PcG and TrxG complexes to DNA. Using a combination of proximity ligation assay-based techniques and super-resolution microscopy, we found that the number of protein-DNA and RNA-DNA foci undergoes significant reduction during mitosis, suggesting that mitosis may be accompanied by structural re-arrangement or compaction of specific chromatin domains
Recommended from our members
Designing information for families caring for people with dementia
A health communication project, to develop information to support families caring for people with dementia, is described. Close collaboration of designers with carers – ‘experts by experience’ – and clinicians and other professionals – ‘experts by training’ – was used. Carer consultation led to a printed (rather than digital) handbook. An iterative process of carer and clinician consultation and design shaped the material form of the handbook. Carers’ needs for different kinds of information were met by a modular approach, and tailored module design. Evaluation following distribution of the handbook suggested it improved carers’ understanding of dementia significantly compared to the information from diverse sources supplied previously. It did not, however, influence people’s confidence in their ability to care, which appeared to be supported better through carer education courses. The specific contribution of information design and its potential for delivering return on investment are discussed
Reducing the drag: creating v formations through slow scholarship and story
Every seed destroys its container, or else there would be no fruition (Scott-Maxwell, 1979). We are three women working across two Australian universities. Frustrated at the deadening, withering nature and containment of the neoliberal university, and inspired by the wisdom of slow scholarship and the cooperative reciprocity inherent in the V formations adopted by groups of flying birds to boost vital energy, our chapter encapsulates our efforts to ‘care for self and others’ and ‘count what others don’t’. It follows our attempts to resist the insidious, diminishing drag of metric-based audits and managerialism. Having joyfully discovered we have ‘outgrown’ narrow academic containers of measurement, comparison, and productivity, we are responding to our longing to connect and to ‘be’ differently in academia. Our resistance is characterised by efforts to listen and converse in meaningful ways, ways that speak our lives into the academy. For over a year we have been initiating conversations with a trusted group of colleagues and acquiring responsive, personal and aesthetic ways to address and reconcile our personal/professional lives. Inviting the reader into our deliberate storying and de-storying of our lived experience whilst practicing a politics of care, collaboration and authenticity, we are subverting what it means to be productive and accountable and what it means to be an academic. And in so doing we are seeding new and fruitful ways of working. We are unearthing our individual and collective voice, and creating and expanding safe spaces for scholarly, professional and personal disclosure and meaning-making
Wind tunnel investigation of an oblique wing transport model at mach numbers between 0.6 and 1.4
Models of three practical oblique-wing transport configurations were tested in the NASA Ames 11 foot wind tunnel. The three configurations used a common forward fuselage, wing, and support system but employed different aft fuselage sections simulating alternate propulsion system installations. These included an integrated propulsion system, pylon-mounted nacelles, and clean (no propulsion system) configuration. The tests were conducted over a Mach number range from 0.6 to 1.4 and at sweep angles from 0 to 60 degrees. The nominal unit Reynolds number was 1.83 million per meter and the angle of attack range was -3 to +6 degrees. The models were mounted in the tunnel by means of a lower blade support system. The interference effects of this lower blade and the flow inclination were determined by using an image blade system and testing the configuration in both the upright and inverted positions
What Every Faculty Developer Needs to Know about Learning Groups
This article advances two related propositions. One is that virtually all of the commonly reported problems with learning groups, such as less content coverage, free-riders, and students\u27 feeling that instructors are not teaching unless they are talking, are a natural consequence of they way the groups are being used. The other is that the vast majority of the problems can be prevented by avoiding group assignments that retard the development of effective learning teams and limit student learning. This article will a) examine the underlying causes of the most commonly reported problems with learning groups, b) outline some simple, but effective, strategies for preventing their occurrence in the first place and, c) describe a new tool, the Learning Activity Impact Grid (LAI-Grid), that can be used to ensure that assignments promote both team development and learning
Mechanisms for Non-Trivial Magnetization Plateaux of an S=1 Frustrated Spin Ladder
We investigate the non-trivial magnetization plateau at 1/4 of the saturation
magnetization of S=1 spin ladder, especially with reference to recent
experimental results on a new organic tetraradical
3,3',5,5'-tetrakis(N-tert-butylaminoxyl)biphenyl, abbreviated as BIP-TENO. We
propose three mechanisms for the formation of the plateau; the Neel mechanism,
the dimer mechanism and the spin-Peierls mechanism. We also discuss the effect
of four-spin exchange interactions.Comment: 3 pages, 5 figures, Orbital2001 (International Conference on Strongly
Correlated Electrons with Orbital Degrees of Freedom) (September 11-14, 2001.
Sendai
Brain structure in pediatric Tourette syndrome
Previous studies of brain structure in Tourette syndrome (TS) have produced mixed results, and most had modest sample sizes. In the present multicenter study, we used structural magnetic resonance imaging (MRI) to compare 103 children and adolescents with TS to a well-matched group of 103 children without tics. We applied voxel-based morphometry methods to test gray matter (GM) and white matter (WM) volume differences between diagnostic groups, accounting for MRI scanner and sequence, age, sex and total GM+WM volume. The TS group demonstrated lower WM volume bilaterally in orbital and medial prefrontal cortex, and greater GM volume in posterior thalamus, hypothalamus and midbrain. These results demonstrate evidence for abnormal brain structure in children and youth with TS, consistent with and extending previous findings, and they point to new target regions and avenues of study in TS. For example, as orbital cortex is reciprocally connected with hypothalamus, structural abnormalities in these regions may relate to abnormal decision making, reinforcement learning or somatic processing in TS
Engineering advice in policy-making: a new domain of inquiry in evidence and policy
Background. Academic research on technical advice to policy commonly focuses on social
and related policy areas such as health, education and crime (Oliver et al. 2014) and
disciplinary advice from science disciplines (Jasanoff 1994; Millstone and van Zwanenberg
2001). Little or no prior research in the social sciences have explored engineering expertise
in policy domains where such advice is critical (e.g. energy policy).
Aims and objectives. We aim to establish ‘engineering advice’ as a new domain of inquiry
by showing how civil servants view it as distinctive (from ‘science advice’), important and
similar to policy making – implying it can clash or complement it.
Methods. 18 qualitative interviews with a purposive sample of officials across a UK ministry
were conducted by the authors (all but one of whom were civil servants) in 2012. The
qualitative data were thematically coded to address the study aims.
Findings. A majority of officials spontaneously identified engineering expertise as both
distinctive and important for their work. There was clear evidence that it both
complemented and clashed with policymaking.
Discussion. We identified a range of interactions that imply a need to consider styles of
management internal deployment of experts within policy organisations as well as the
implications for policy making and engineering expertise given the way practices overlap.
Conclusions. Further research on the ontological, epistemological nature of engineering as it
relates to policy making is needed if governments and therefore society are to fully benefit
from engineering advice
Detection of 6 K gas in Ophiuchus D
Cold cores in interstellar molecular clouds represent the very first phase in
star formation. The physical conditions of these objects are studied in order
to understand how molecular clouds evolve and how stellar masses are
determined. The purpose of this study is to probe conditions in the dense,
starless clump Ophichus D (Oph D). The ground-state (1(10)-1(11)) rotational
transition of ortho-H2D+ was observed with APEX towards the density peak of Oph
D. The width of the H2D+ line indicates that the kinetic temperature in the
core is about 6 K. So far, this is the most direct evidence of such cold gas in
molecular clouds. The observed H2D+ spectrum can be reproduced with a
hydrostatic model with the temperature increasing from about 6 K in the centre
to almost 10 K at the surface. The model is unstable against any increase in
the external pressure, and the core is likely to form a low-mass star. The
results suggest that an equilibrium configuration is a feasible intermediate
stage of star formation even if the larger scale structure of the cloud is
thought to be determined by turbulent fragmentation. In comparison with the
isothermal case, the inward decrease in the temperature makes smaller, i.e.
less massive, cores susceptible to externally triggered collapse.Comment: 7 pages, 5 figures, accepted for Astronomy and Astrophysic
- …