Algorithm for numerical integration of the rigid-body equations of motion

A new algorithm for numerical integration of the rigid-body equations of motion is proposed. The algorithm uses the leapfrog scheme and the quantities involved are angular velocities and orientational variables which can be expressed in terms of either principal axes or quaternions. Due to specific features of the algorithm, orthonormality and unit norms of the orientational variables are integrals of motion, despite an approximate character of the produced trajectories. It is shown that the method presented appears to be the most efficient among all known algorithms of such a kind.Comment: 4 pages, 1 figur

Development Studies Working Paper, no. 13

In Ciskei, the development of urban housing and local authority structures has not been able to keep up with this immigration. As a result, a number of communities have sprung up in the tribal Authority areas close to this conurbation of some half a million people. These communities are neither urban nor rural, and comprise people with rural farmworker backgrounds who obtain their main source of income from employment in urban areas. In contradistinction to their true rural cousins, the breadwinners in these communities do not need to become migrants living and working far from home. Rather, they work during the week in an urban location close to home, and return on weekends to their families and children. This volume reports on one such community. The settlement of Tsweletswele is new, situated in a Tribal area, and within thirty kilometres of East London. Its residents who came from farms in the region work in East London. Their level of living is low, their access to state services minimal, and their tenure in the settlement uncertain. This report aims quite simply to establish what strategies these people choose to survive in their settlement. Subsequently, a set of recommendations are made which are aimed at improving the levels of living in the community, the delivery of essential services, and the tenure arrangements in the settlementDigitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER

Problem-based learning in dental education: what's the evidence for and against... and is it worth the effort?

The document attached has been archived with permission from the Australian Dental Association. An external link to the publisher’s copy is included.All Australian dental schools have introduced problem-based learning (PBL) approaches to their programmes over the past decade, although the nature of the innovations has varied from school to school. Before one can ask whether PBL is better than the conventional style of education, one needs to consider three key issues. Firstly, we need to agree on what is meant by the term PBL; secondly, we need to decide what “better” means when comparing educational approaches; and thirdly, we must look carefully at how PBL is implemented in given situations. It is argued that PBL fulfils, at least in theory, some important principles relating to the development of new knowledge. It also represents a change in focus from teachers and teaching in conventional programmes to learners and learning. Generally, students enjoy PBL programmes more than conventional programmes and feel they are more nurturing. There is also some evidence of an improvement in clinical and diagnostic reasoning ability associated with PBL curricula. The main negative points raised about PBL are the costs involved and mixed reports of insufficient grounding of students in the basic sciences. Financial restraints will probably preclude the introduction of pure or fully integrated PBL programmes in Australian dental schools. However, our research and experience, as well as other published literature, indicate that well-planned hybrid PBL programmes, with matching methods of assessment, can foster development of the types of knowledge, skills and attributes that oral health professionals will need in the future.T Winning and G Townsen

Creating Non-Believed Memories for Recent Autobiographical Events

A recent study showed that many people spontaneously report vivid memories of events that they do not believe to have occurred [1]. In the present experiment we tested for the first time whether, after powerful false memories have been created, debriefing might leave behind nonbelieved memories for the fake events. In Session 1 participants imitated simple actions, and in Session 2 they saw doctored video-recordings containing clips that falsely suggested they had performed additional (fake) actions. As in earlier studies, this procedure created powerful false memories. In Session 3, participants were debriefed and told that specific actions in the video were not truly performed. Beliefs and memories for all critical actions were tested before and after the debriefing. Results showed that debriefing undermined participants' beliefs in fake actions, but left behind residual memory-like content. These results indicate that debriefing can leave behind vivid false memories which are no longer believed, and thus we demonstrate for the first time that the memory of an event can be experimentally dissociated from the belief in the event's occurrence. These results also confirm that belief in and memory for an event can be independently-occurring constructs

Hydrodynamic interactions in colloidal ferrofluids: A lattice Boltzmann study

We use lattice Boltzmann simulations, in conjunction with Ewald summation methods, to investigate the role of hydrodynamic interactions in colloidal suspensions of dipolar particles, such as ferrofluids. Our work addresses volume fractions $\phi$ of up to 0.20 and dimensionless dipolar interaction parameters $\lambda$ of up to 8. We compare quantitatively with Brownian dynamics simulations, in which many-body hydrodynamic interactions are absent. Monte Carlo data are also used to check the accuracy of static properties measured with the lattice Boltzmann technique. At equilibrium, hydrodynamic interactions slow down both the long-time and the short-time decays of the intermediate scattering function $S(q,t)$, for wavevectors close to the peak of the static structure factor $S(q)$, by a factor of roughly two. The long-time slowing is diminished at high interaction strengths whereas the short-time slowing (quantified via the hydrodynamic factor $H(q)$) is less affected by the dipolar interactions, despite their strong effect on the pair distribution function arising from cluster formation. Cluster formation is also studied in transient data following a quench from $\lambda = 0$; hydrodynamic interactions slow the formation rate, again by a factor of roughly two

Amelogenin Nanoparticles in Suspension: Deviations from Spherical Shape and pH-Dependent Aggregation

It is well-known that amelogenin self-assembles to form nanoparticles, usually referred to as amelogenin nanospheres, despite the fact that not much is known about their actual shape in solution. In the current paper, we combine SAXS and DLS to study the three-dimensional shape of the recombinant amelogenins rP172 and rM179. Our results show for the first time that amelogenins build oblate nanoparticles in suspension using experimental approaches that do not require the proteins to be in contact with a support material surface. The SAXS studies give evidence for the existence of isolated amelogenin nano-oblates with aspect ratios in the range of 0.45-0.5 at pH values higher than pH 7.2 and show an aggregation of these nano-oblates at lower pH values. The role of the observed oblate shape in the formation of chain-like structures at physiological conditions is discussed as a key factor in the biomineralization of dental enamel

A randomised controlled feasibility trial of music-assisted language telehealth intervention for minimally verbal autistic children-the MAP study protocol.

BACKGROUND: About 30% of children with autism spectrum disorder (ASD) do not develop functional speech and remain non-verbal or minimally verbal even after years of speech, language and educational interventions. A wide range of interventions have been developed for improving communication in ASD, but none have proved effective in eliciting functional language in ASD children. Research has found that people with ASD are more likely to have perfect pitch and prefer music to language. Further, it seems that language delay tends to co-occur with better musical skills. Brain imaging research has found that music alongside words increases the attention that people with ASD pay to spoken words. METHODS: In this protocol, we describe our music-assisted programmes (MAP) that will use music to attract the attention of people with ASD to speech. MAP may open the brain pathways to language and therefore help improve communication skills for people with ASD more than standard communication protocols. In particular, we aim to develop and test whether individualised, easily used MAP would increase spoken language in 24-60-month-old, nonverbal or minimally verbal children with ASD. We will develop a structured training method, delivered through naturalistic, interactive activities (e.g. songs) to teach language to ASD children. We will test this by comparing two groups: one undertaking music-assisted programmes, and the other receiving speech and language therapy in the way that is recommended in NHS clinics. Participants will be allocated to groups randomly. The feasibility of MAP will be assessed through estimations of recruitment and retention rates, the sensitivity and reliability of the outcome measures, the intensity and frequency of the trial, the usability of the MAP app (beta version), and the burden of the assessments for the children and parents. DISCUSSION: This feasibility randomised controlled trial will establish the acceptability and estimate the power of the MAP intervention to improve early word learning in children with ASD. In the longer term, this research will help us develop an app for parents or carers of children with ASD to design their own songs and implement their own individualised MAP. TRIAL REGISTRATION: ISRCTN, ISRCTN12536062 . Registered on 26 June 2019