Binding branched and linear DNA structures: from isolated clusters to fully bonded gels

The proper design of DNA sequences allows for the formation of well defined supramolecular units with controlled interactions via a consecution of self-assembling processes. Here, we benefit from the controlled DNA self-assembly to experimentally realize particles with well defined valence, namely tetravalent nanostars (A) and bivalent chains (B). We specifically focus on the case in which A particles can only bind to B particles, via appropriately designed sticky-end sequences. Hence AA and BB bonds are not allowed. Such a binary mixture system reproduces with DNA-based particles the physics of poly-functional condensation, with an exquisite control over the bonding process, tuned by the ratio, r, between B and A units and by the temperature, T. We report dynamic light scattering experiments in a window of Ts ranging from 10{\deg}C to 55{\deg}C and an interval of r around the percolation transition to quantify the decay of the density correlation for the different cases. At low T, when all possible bonds are formed, the system behaves as a fully bonded network, as a percolating gel and as a cluster fluid depending on the selected r.Comment: 15 pages, 11 figure

Evidence of a Metal Rich Galactic Bar from the Vertex Deviation of the Velocity Ellipsoid

We combine radial velocities, proper motions, and low resolution abundances for a sample of 315 K and M giants in the Baade's Window (l,b)=(0.9,-4) Galactic bulge field. The velocity ellipsoid of stars with [Fe/H]>-0.5 dex shows a vertex deviation in the plot of radial versus transverse velocity, consistent with that expected from a population with orbits supporting a bar. We demonstrate that the significance of this vertex deviation using non-parametric rank correlation statistic is >99%. The velocity ellipsoid for the metal poor ([FeH]<-0.5) part of the population shows no vertex deviation and is consistent with an isotropic, oblate rotating population. We find no evidence for kinematic subgroups, but there is a mild tendency for the vertical velocity dispersion sigma_b to decrease with increasing metallicity.Comment: 4 pages, ApJ Letters, submitte

Innovating Pedagogy 2015: Open University Innovation Report 4

This series of reports explores new forms of teaching, learning and assessment for an interactive world, to guide teachers and policy makers in productive innovation. This fourth report proposes ten innovations that are already in currency but have not yet had a profound influence on education. To produce it, a group of academics at the Institute of Educational Technology in The Open University collaborated with researchers from the Center for Technology in Learning at SRI International. We proposed a long list of new educational terms, theories, and practices. We then pared these down to ten that have the potential to provoke major shifts in educational practice, particularly in post-school education. Lastly, we drew on published and unpublished writings to compile the ten sketches of new pedagogies that might transform education. These are summarised below in an approximate order of immediacy and timescale to widespread implementation

AN ALTERNATIVE METHOD TO THAT OF THE R6 PROCEDURE FOR THE TREATMENT OF COMBINED PRIMARY AND SECONDARY LOADING

ABSTRACT An alternative definition for the assessment point parameter of the R6 defect assessment procedure is proposed, for combined primary and secondary loading. This alternative definition removes the requirement to calculate a plasticity correction factor for secondary stresses, ρ (or V), used in the conventional R6 definition of . To compare these definitions, both the R6 procedure and the alternative method are presented as Crack Driving Force (CDF) estimation schemes. The required inputs to these estimation schemes have been determined from finite element analyses, for the particular case, of a thick-walled cylinder with a fully circumferential internal defect and subjected to internal pressure and a radial through-wall temperature gradient. Comparisons of CDF estimates with those determined from full inelastic finite element analyses have shown, for the cases studied, that both the R6 and alternative approaches provide conservative estimates of CDF compared to those obtained from finite element analyses, with the degree of conservatism far greater for the conventional R6 approach. Further finite element validation with different geometries, loadings and material properties is required before the alternative procedure could be considered for inclusion in the R6 defect assessment procedure as an alternative to the procedure of the main section of the document

Isotopic analysis of faunal material from South Uist, Western Isles, Scotland

This paper reports on the results from stable isotope analysis of faunal bone collagen from a number of Iron Age and later sites on the island of South Uist, in the Western Isles, Scotland. This preliminary investigation into the isotopic signatures of the fauna is part of a larger project to model the interaction between humans, animals, and the broader environment in the Western Isles. The results demonstrate that the island fauna data fall within the range of expected results for the UK, with the terrestrial herbivorous diets of cattle and sheep confi rmed. The isotopic composition for pigs suggests that some of these animals had an omnivorous diet, whilst a single red deer value might be suggestive of the consumption of marine foods, such as by grazing on seaweed. However, further analysis is needed in order to verify this anomalous isotopic ratio

Promoting proactive bystander responses to racism and racial discrimination in primary schools: a mixed methods evaluation of the ‘Speak Out Against Racism’ program pilot

BackgroundRacism and racial discrimination are fundamental causes and determinants of health and health inequalities globally, with children and adolescents particularly vulnerable. Racial discrimination is a common stressor in the lives of many children and adolescents, with growing evidence of negative associations between racial discrimination and multiple domains of child and adolescent health. Addressing racism and racial discrimination must be core public health priorities, even more so among children and young people. Schools are key settings in the lives of children and adolescents and become increasingly more important to identity formation. School communities, teachers and peers greatly influence children and adolescents' beliefs about race and difference. Schools are therefore key sites for the delivery of population-based programs to reduce racism and promote proactive bystander behaviour and healthy resistance to racism among all children and adolescents as well as among the adults.MethodsThis study examines the feasibility and acceptability of the 'Speak Out Against Racism (SOAR)' program, a whole of school, multi-level, multi-strategy program that aimed to promote effective bystander responses to racism and racial discrimination in primary schools. A mixed-methods, quasi-experimental design was used. Students in Years 5 and 6 (10-12 years) across six schools completed surveys pre- and post- intervention (N = 645; 52% female; 6% Indigenous, 10% Middle Eastern, African, Latinx or Pacific Islander, 21% Asian, 52% Anglo/European). Focus groups with students and interviews with staff collected qualitative data about their experiences of the program and their views about the program's perceived need, implementation, impacts and suggested improvements.ResultsQuantitative data showed student prosocial skills and teacher inter-racial climate improved in intervention schools compared to comparison schools. Qualitative data highlighted teacher attitudinal and behaviour change regarding racism, and student reduced interpersonal racial discrimination, improved peer prosocial norms, commitment to anti-racism, knowledge of proactive bystander responses and confidence and self-efficacy to intervene to address racism.ConclusionsThis study provides quantitative evidence of the potential of the SOAR program to improve the prosocial skills of students and their perceptions of the inter-racial school climate provided by their teachers. This program also provided qualitative evidence of the potential to promote teacher and student attitudinal and behavioural change. Further refinement and testing of the program in a large scale implementation trial is recommended

Application of the finite-temperature Lanczos method for the evaluation of magnetocaloric properties of large magnetic molecules

We discuss the magnetocaloric properties of gadolinium containing magnetic molecules which potentially could be used for sub-Kelvin cooling. We show that a degeneracy of a singlet ground state could be advantageous in order to support adiabatic processes to low temperatures and simultaneously minimize disturbing dipolar interactions. Since the Hilbert spaces of such spin systems assume very large dimensions we evaluate the necessary thermodynamic observables by means of the Finite-Temperature Lanczos Method.Comment: 7 pages, 10 figures, invited for the special issue of EPJB on "New trends in magnetism and magnetic materials

Lifespan theorem for constrained surface diffusion flows

We consider closed immersed hypersurfaces in $\R^{3}$ and $\R^4$ evolving by a class of constrained surface diffusion flows. Our result, similar to earlier results for the Willmore flow, gives both a positive lower bound on the time for which a smooth solution exists, and a small upper bound on a power of the total curvature during this time. By phrasing the theorem in terms of the concentration of curvature in the initial surface, our result holds for very general initial data and has applications to further development in asymptotic analysis for these flows.Comment: 29 pages. arXiv admin note: substantial text overlap with arXiv:1201.657