‘Putting apes (body and language) together again’, a review article of Savage-Rumbaugh, S., Taylor, T. J., and Shanker, S. G. Apes, Language, and the Human Mind (Oxford: 1999) and Clark, A. Being There: Putting Brain, Body, and World Together Again (MIT: 1997)

It is argued that the account of Savage-Rumbaugh’s ape language research in Savage-Rumbaugh, Shanker and Taylor (1998. Apes, Language and the Human Mind. Oxford University Press, Oxford) is profitably read in the terms of the theoretical perspective developed in Clark (1997. Being There, Putting Brain, Body and World Together Again. MIT Press, Cambridge, MA). The former work details some striking results concerning chimpanzee and bonobo subjects, trained to make use of keyboards containing ‘lexigram’ symbols. The authors, though, make heavy going of a critique of what they take to be standard approaches to understanding language and cognition in animals, and fail to offer a worthwhile theoretical position from which to make sense of their own data. It is suggested that the achievements of Savage-Rumbaugh’s non-human subjects suggest that language ability need not be explained by reference to specialised brain capacities. The contribution made by Clark’s work is to show the range of ways in which cognition exploits bodily and environmental resources. This model of ‘distributed’ cognition helps makes sense of the lexigram activity of Savage-Rumbaugh’s subjects, and points to a re-evaluation of the language behaviour of humans

On the instability of hypersonic flow past a wedge

The instability of a compressible flow past a wedge is investigated in the hypersonic limit. Particular attention is given to the Tollmien-Schlichting waves governed by triple-deck theory though some discussion of inviscid modes is given. It is shown that the attached shock has a significant effect on the growth rates of Tollmien-Schlichting waves. Moreover, the presence of the shock allows for more than one unstable Tollmien-Schlichting wave. Indeed, an infinite discrete spectrum of unstable waves is induced by the shock, but these modes are unstable over relatively small but high frequency ranges. The shock is shown to have little effect on the inviscid modes considered by previous authors and an asymptotic description of inviscid modes in the hypersonic limit is given

Teaching the Doppler Effect in Astrophysics

The Doppler effect is a shift in the frequency of waves emitted from an object moving relative to the observer. By observing and analysing the Doppler shift in electromagnetic waves from astronomical objects, astronomers gain greater insight into the structure and operation of our universe. In this paper, a simple technique is described for teaching the basics of the Doppler effect to undergraduate astrophysics students using acoustic waves. An advantage of the technique is that it produces a visual representation of the acoustic Doppler shift. The equipment comprises a 40 kHz acoustic transmitter and a microphone. The sound is bounced off a computer fan and the signal collected by a DrDAQ ADC and processed by a spectrum analyser. Widening of the spectrum is observed as the fan power supply potential is increased from 4 to 12 V.Comment: 9 pages, 5 figures, published in Eur. J. Phy

On the Lagrangian description of unsteady boundary layer separation. Part 1: General theory

Although unsteady, high-Reynolds number, laminar boundary layers have conventionally been studied in terms of Eulerian coordinates, a Lagrangian approach may have significant analytical and computational advantages. In Lagrangian coordinates the classical boundary layer equations decouple into a momentum equation for the motion parallel to the boundary, and a hyperbolic continuity equation (essentially a conserved Jacobian) for the motion normal to the boundary. The momentum equations, plus the energy equation if the flow is compressible, can be solved independently of the continuity equation. Unsteady separation occurs when the continuity equation becomes singular as a result of touching characteristics, the condition for which can be expressed in terms of the solution of the momentum equations. The solutions to the momentum and energy equations remain regular. Asymptotic structures for a number of unsteady 3-D separating flows follow and depend on the symmetry properties of the flow. In the absence of any symmetry, the singularity structure just prior to separation is found to be quasi 2-D with a displacement thickness in the form of a crescent shaped ridge. Physically the singularities can be understood in terms of the behavior of a fluid element inside the boundary layer which contracts in a direction parallel to the boundary and expands normal to it, thus forcing the fluid above it to be ejected from the boundary layer

On the instability of hypersonic flow past a flat plate

The instability of hypersonic boundary-layer flows over flat plates is considered. The viscosity of the fluid is taken to be governed by Sutherland's law, which gives a much more accurate representation of the temperature dependence of fluid viscosity at hypersonic speeds than Chapman's approximate linear law; although at lower speeds the temperature variation of the mean state is less pronounced so that the Chapman law can be used with some confidence. Attention is focussed on the so-called (vorticity) mode of instability of the viscous hypersonic boundary layer. This is thought to be the fastest growing inviscid disturbance at hypersonic speeds; it is also believed to have an asymptotically larger growth rate than any viscous or centrifugal instability. As a starting point the instability of the hypersonic boundary layer which exists far downstream from the leading edge of the plate is investigated. In this regime the shock that is attached to the leading edge of the plate plays no role, so that the basic boundary layer is non-interactive. It is shown that the vorticity mode of instability of this flow operates on a significantly different lengthscale than that obtained if a Chapman viscosity law is assumed. In particular, it is found that the growth rate predicted by a linear viscosity law overestimates the size of the growth rate by O(M(exp 2). Next, the development of the vorticity mode as the wavenumber decreases is described, and it is shown that acoustic modes emerge when the wavenumber has decreased from it's O(1) initial value to O(M (exp -3/2). Finally, the inviscid instability of the boundary layer near the leading edge in the interaction zone is discussed and particular attention is focussed on the strong interaction region which occurs sufficiently close to the leading edge. It is found that the vorticity mode in this regime is again unstable, and that it is concentrated in the transition layer at the edge of the boundary layer where the temperature adjusts from its large, O(M(exp 2), value in the viscous boundary layer, to its O(1) free stream value. The existence of the shock indirectly, but significantly, influences the instability problem by modifying the basic flow structure in this layer

On the nonlinear three dimensional instability of Stokes layers and other shear layers to pairs of oblique waves

The nonlinear evolution of a pair of initially oblique waves in a high Reynolds Number Stokes layer is studied. Attention is focused on times when disturbances of amplitude epsilon have O(epsilon(exp 1/3)R) growth rates, where R is the Reynolds number. The development of a pair of oblique waves is then controlled by nonlinear critical-layer effects. Viscous effects are included by studying the distinguished scaling epsilon = O(R(exp -1)). This leads to a complicated modification of the kernel function in the integro-differential amplitude equation. When viscosity is not too large, solutions to the amplitude equation develop a finite-time singularity, indicating that an explosive growth can be introduced by nonlinear effects; we suggest that such explosive growth can lead to the bursts observed in experiments. Increasing the importance of viscosity generally delays the occurrence of the finite-time singularity, and sufficiently large viscosity may lead to the disturbance decaying exponentially. For the special case when the streamwise and spanwise wavenumbers are equal, the solution can evolve into a periodic oscillation. A link between the unsteady critical-layer approach to high-Reynolds-number flow instability, and the wave vortex approach is identified

OH&S in small business : Influencing the decision makers : The application of a social marketing model to increase the uptake of OHS risk control

Losses resulting from traumatic injuries and occupational disease are prevalent in the small business sector of Australian industry. Although the true size of the problem is unclear, it is estimated that the losses amount to more than $8 billion annually. The hazard control measures to counter these losses are largely known and are available to small businesses but they are not widely adopted. Regulators and other bodies have employed a range of intervention strategies to influence decision-makers in small businesses but most have focussed on the dissemination of printed materials or broadbased advertising campaigns with limited success......... The research concludes that the listening processes at the heart of social marketing add to the methods already used in the OHS discipline by forcing the marketer to listen to the subjective assessment of risk as perceived by targets as well as to question the evidence base that supports the legitimacy and efficacy of the proposed intervention. The TTM was found to be a useful means of categorising small business decision-maker behaviour and assessing the readiness for change of individuals and therefore the messages that are needed to unfreeze behaviour. The TTM also provides a tool for evaluation of the impact of an intervention.As a result of this research it is suggested that opinion leaders, who are employed within a social marketing model to diffuse information, multiply the effort of those wishing to increase the adoption of an innovation. Thus engagement of opinion leaders by an OHS authority for the communication of risk control messages may be more cost-effective than attempting to visit every workplace within an industry group. Thus, although social marketing is not in the general repertoire of OHS interventions, it appears to be extremely useful as a framework for interventions and, when used in concert with a stages of change model, provides natural lead indicators for evaluating the impact of OHS interventions. Application of social marketing to people who have the responsibility for the health and safety of others was unique.Doctor of Philosph