Resonant whirling of two-piece propshafts in rear-wheel-drive cars

Many modern cars with rear-wheel drives have a two-piece, rather than the traditional one-piece, props haft (or tail-shaft). The two-piece shaft requires less floor clearance, and hence a smaller floor tunnel, and does not suffer from the high-speed twisting resonances to which the one-piece shaft is susceptible. The two-piece shaft is, however, susceptible to a lower speed, high load (high torque) phenomenon in which the propshaft whirls with increasing amplitude until its restraining rubber bush is fully compressed in its mounting bracket, causing a thump sound. The whirling amplitude builds up periodically, so that a regular series of thumps is heard at a frequency of about 5 per second. The effect is very sensitive to the properties of the rubber bush and to its temperature. Different designs of bush are used by different makers, each with the purpose of minimizing both the whirling problem and the transmission of other vibrations to the car body. GMH has a particular design which it would prefer not to vary, because of retooling costs. It can however vary the properties of the rubber material itself. By trial and error it has achieved rubber properties which control the whirling problem to an acceptable level under normal conditions. GMH posed the question, to the MISG, of whether one can give theoretical guidelines for optimal rubber properties. This might lead to improved control of the whirling problem. It would also be useful for new and modified propshafts, if it could replace the tedious trial and error process previously employed. GMH were also anxious to gain a better understanding of the whirling phenomenon, and felt, with us, that a mathematical description of the phenomenon was a prerequisite for the study of the rubber properties. The thumping phenomenon is observed at both 40 and 80 kph approximately, although the phenomenon had a different quality at these two speeds

Think Different: Applying the Old Macintosh Mantra to the Computability of the SUSY Auxiliary Field Problem

Starting with valise supermultiplets obtained from 0-branes plus field redefinitions, valise adinkra networks, and the "Garden Algebra," we discuss an architecture for algorithms that (starting from on-shell theories and, through a well-defined computation procedure), search for off-shell completions. We show in one dimension how to directly attack the notorious "off-shell auxiliary field" problem of supersymmetry with algorithms in the adinkra network-world formulation.Comment: 28 pages, 1 figur

The advanced solar cell orbital test

The motivation for advanced solar cell flight experiments is discussed and the Advanced Solar Cell Orbital Test (ASCOT) flight experiment is described. Details of the types of solar cells included in the test and the kinds of data to be collected are given. The orbit will expose the cells to a sufficiently high radiation dose that useful degradation data will be obtained in the first year

Non-Minimal String Corrections And Supergravity

We reconsider the well-known issue of string corrections to Supergravity theory. Our treatment is carried out to second order in the string slope parameter. We establish a procedure for solving the Bianchi identities in the non minimal case, and we solve a long standing problem in the perturbative expansion of D=10, N=1 string corrected Supergravity, obtaining the H sector tensors, torsions and curvatures.Comment: 19 pages, PACS number: 04.65.+

Mechanical chest-compression devices: current and future roles

Purpose of review: It is recognised that the quality of CPR is an important predictor of outcome from cardiac arrest yet studies consistently demonstrate that the quality of CPR performed in real life is frequently sub-optimal. Mechanical chest compression devices provide an alternative to manual CPR. This review will consider the evidence and current indications for the use of these devices. Recent findings: Physiological and animal data suggest that mechanical chest compression devices are more effective than manual CPR. However there is no high quality evidence showing improved outcomes in humans. There are specific circumstances where it may not be possible to perform manual CPR effectively e.g. during ambulance transport to hospital, en-route to and during cardiac catheterisation, prior to organ donation and during diagnostic imaging where using these devices may be advantageous. Summary: There is insufficient evidence to recommend the routine use of mechanical chest compression devices. There may be specific circumstances when CPR is difficult or impossible where mechanical devices may play an important role in maintaining circulation. There is an urgent need for definitive clinical and cost effectiveness trials to confirm or refute the place of mechanical chest compression devices during resuscitation

On Supermultiplet Twisting and Spin-Statistics

Twisting of off-shell supermultiplets in models with 1+1-dimensional spacetime has been discovered in 1984, and was shown to be a generic feature of off-shell representations in worldline supersymmetry two decades later. It is shown herein that in all supersymmetric models with spacetime of four or more dimensions, this off-shell supermultiplet twisting, if non-trivial, necessarily maps regular (non-ghost) supermultiplets to ghost supermultiplets. This feature is shown to be ubiquitous in all fully off-shell supersymmetric models with (BV/BRST-treated) constraints.Comment: Extended version, including a new section on manifestly off-shell and supersymmetric BRST treatment of gauge symmetry; added reference

The early expansion and evolutionary dynamics of POU class genes.

The POU genes represent a diverse class of animal-specific transcription factors that play important roles in neurogenesis, pluripotency, and cell-type specification. Although previous attempts have been made to reconstruct the evolution of the POU class, these studies have been limited by a small number of representative taxa, and a lack of sequences from basally branching organisms. In this study, we performed comparative analyses on available genomes and sequences recovered through "gene fishing" to better resolve the topology of the POU gene tree. We then used ancestral state reconstruction to map the most likely changes in amino acid evolution for the conserved domains. Our work suggests that four of the six POU families evolved before the last common ancestor of living animals-doubling previous estimates-and were followed by extensive clade-specific gene loss. Amino acid changes are distributed unequally across the gene tree, consistent with a neofunctionalization model of protein evolution. We consider our results in the context of early animal evolution, and the role of POU5 genes in maintaining stem cell pluripotency