Francis Bacon and the practice of painting

This article addresses the question about why painting continues to be relevant in our contemporary cultural climate. A key reason can be located in the means by which the material of paint can be utilized, manipulated, and perceived through entire sensory and bodily mechanisms. As the practice of Francis Bacon (1909–1992) demonstrates, it is within the elusive behaviour and handling of pigment that the full transformative potential of painting can be released. In fact it can activate a whole field of sensory responses on the part of painter and viewer. The painter can manipulate the material to achieve a variety of effects but needs also to acknowledge how the material can potentially assume an independent life of its own, an almost unruly character. The strength and enduring quality of painting which links modern to postmodern practice, lies in its potential to utilise the painter's tacit skills as well as releasing the inherent and ‘unruly’ qualities of the pigment. The potential of painting practice lies within the orbit of the individual painter who can recognize implicitly how to let the paint ‘work’ according to the needs of the image being constructed

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

Preface - rethinking structural reform in Latin America

The process of structural reform in Latin America has thus far been uneven, and various economic crises have raised doubts about reforms’ effectiveness and have caused public support for further reforms to wane. To promote and highlight research exploring structural reform’s impact on economic growth and income distribution in Latin America, the Federal Reserve Bank of Atlanta and the Inter-American Development Bank (IDB) cosponsored the conference “Rethinking Structural Reform in Latin America” in October 2003. ; This issue of the Economic Review contains four articles that were among the papers presented at the conference. The preface summarizes the conference speeches, papers, and discussant comments.Economic stabilization

Practical Bayesian Optimization for Variable Cost Objectives

We propose a novel Bayesian Optimization approach for black-box functions with an environmental variable whose value determines the tradeoff between evaluation cost and the fidelity of the evaluations. Further, we use a novel approach to sampling support points, allowing faster construction of the acquisition function. This allows us to achieve optimization with lower overheads than previous approaches and is implemented for a more general class of problem. We show this approach to be effective on synthetic and real world benchmark problems.Comment: 8 pages, 7 figure

Deflection of a Viscoelastic Cantilever under a Uniform Surface Stress: Applications to Static-mode Microcantilever Sensors Undergoing Adsorption

The equation governing the curvature of a viscoelastic microcantilever beam loaded with a uniform surface stress is derived. The present model is applicable to static-mode microcantilever sensors made with a rigid polymer, such as SU-8. An analytical solution to the differential equation governing the curvature is given for a specific surface stress representing adsorption of analyte onto the viscoelastic beam’s surface. The solution for the bending of the microcantilever shows that, in many cases, the use of Stoney’s equation to analyze stress-induced deflection of viscoelastic microcantilevers (in the present case due to surface analyte adsorption) can lead to poor predictions of the beam’s response. It is shown that using a viscoelastic substrate can greatly increase sensitivity (due to a lower modulus), but at the cost of a longer response time due to viscoelasticcreep in the microcantilever. In addition, the effects of a coating on the cantilever are considered. By defining effective moduli for the coated-beam case, the analytical solution for the uncoated case can still be used. It is found that, unlike the case of a silicon microcantilever, the stress in the coating due to bending of a polymer cantilever can be significant, especially for metalcoatings. The theoretical results presented here can also be used to extract time-domain viscoelasticproperties of the polymermaterial from beam response data