Assessment of field rolling resistance of manual wheelchairs

This article proposes a simple and convenient method for assessing the subject-specific rolling resistance acting on a manual wheelchair, which could be used during the provision of clinical service. This method, based on a simple mathematical equation, is sensitive to both the total mass and its fore-aft distribution, which changes with the subject, wheelchair properties, and adjustments. The rolling resistance properties of three types of front casters and four types of rear wheels were determined for two indoor surfaces commonly encountered by wheelchair users (a hard smooth surface and carpet) from measurements of a three-dimensional accelerometer during field deceleration tests performed with artificial load. The average results provided by these experiments were then used as input data to assess the rolling resistance from the mathematical equation with an acceptable accuracy on hard smooth and carpet surfaces (standard errors of the estimates were 4.4 and 3.9 N, respectively). Thus, this method can be confidently used by clinicians to help users make trade-offs between front and rear wheel types and sizes when choosing and adjusting their manual wheelchair.This material was based on work supported by the SACR-FRM project, French National Research Agency (ANR-06-TecSan-020) and the Centre d’Etudeset de Recherche sur l’Appareillage des Handicapés (loaned all MWCs required to fulfill this work

Optimal Drug Synergy in Antimicrobial Treatments

The rapid proliferation of antibiotic-resistant pathogens has spurred the use of drug combinations to maintain clinical efficacy and combat the evolution of resistance. Drug pairs can interact synergistically or antagonistically, yielding inhibitory effects larger or smaller than expected from the drugs' individual potencies. Clinical strategies often favor synergistic interactions because they maximize the rate at which the infection is cleared from an individual, but it is unclear how such interactions affect the evolution of multi-drug resistance. We used a mathematical model of in vivo infection dynamics to determine the optimal treatment strategy for preventing the evolution of multi-drug resistance. We found that synergy has two conflicting effects: it clears the infection faster and thereby decreases the time during which resistant mutants can arise, but increases the selective advantage of these mutants over wild-type cells. When competition for resources is weak, the former effect is dominant and greater synergy more effectively prevents multi-drug resistance. However, under conditions of strong resource competition, a tradeoff emerges in which greater synergy increases the rate of infection clearance, but also increases the risk of multi-drug resistance. This tradeoff breaks down at a critical level of drug interaction, above which greater synergy has no effect on infection clearance, but still increases the risk of multi-drug resistance. These results suggest that the optimal strategy for suppressing multi-drug resistance is not always to maximize synergy, and that in some cases drug antagonism, despite its weaker efficacy, may better suppress the evolution of multi-drug resistance.Molecular and Cellular Biolog

A Theater of Anxiety: The Irrepresentable in Shelley\u27s The Cenci and in Musset\u27s Lorenzaccio

In this dissertation I develop a comparative study of two outstanding Romantic dramas, Shelley\u27s The Cenci (1819) and Musset\u27s Lorenzaccio (1834), with the purpose of demonstrating that both offer a viable answer to the difficult problems facing the revival of tragedy at the beginning of the Nineteenth Century. Both Shelley and Musset took into account the tragic traditions available in their time, starting with the Greek models, to the evolution and transformation of the genre during Elizabethan and Jacobean periods in England, Neo-classicism in France and the Baroque in Germany. I argue that these plays aggravated in particular the Historical Tragedy created by Shakespeare. They belong to the Aesthetics of the sublime elaborated by the philosophers at the end of the Eighteenth Century (Burke, Kant, Hegel). They were designed to shock audiences by provoking in them the dominant feeling of anxiety. Indeed, the dramatic action and the rhetoric of both plays ceaselessly address the radical fact that language has limits and that beyond there lurks an irrepresentable, unimaginable and undefinable real . Both works center around a cause for anxiety in the central characters which language, i.e. the written text, can only approach indirectly, through elaborate linguistic constructions or sublime metaphors. Relevant analysis by Freud, Heidegger and Lacan allow me to specify anxiety among related feelings (anxiety versus fear). De Quincey\u27s and Mallarme\u27s self-observations at the reception of tragedy confirm the importance of the feeling for modern audiences and provide concrete and personal insights into the mechanism that triggers it in the theater. My overall point is that Shelley and Musset practically responded to the question Kierkegaard was to confront in Either/ Or by the middle of the Century (1843): what would be specific to the Romantic serious drama? They answered in strikingly similar terms to the philosopher\u27s theory by creating what I call, A Theater of Anxiety

Third‐order, nonlinear optical interactions of some benzporphyrins

We measured third‐order, nonlinear optical susceptibility χ(3) for a series of tetrabenzporphyrins in solution in tetrahydrofuran at 532 nm using degenerate four‐wave mixing with picosecond pulses and obtained values of molecular second hyperpolarizability 〈γ〉. The corresponding macroscopic χ(3) values calculated for nine compounds with different substituent groups are four to five orders larger than CS2. For five of the compounds the χ(3) values are in the range 1.2–2.8×10−8 esu. Our experiments indicate that the nonlinearity is predominately electronic in origin with a response time faster than the 15 ps resolution of our system

Magnetic Behavior Of Rare-earth Iron-rich Intermetallic Compounds

The thermal variation of lattice parameters of rare earth-transition metal intermetallic compounds rich in Fe, Co, or Ni in the temperature range of 25-900oK is studied. For the Fe compounds, negative thermal expansion is observed below their magnetic ordering temperatures regardless of the nature of substitutional ordering. For Co and Ni compounds, the thermal expansion behavior is normal. It is then concluded that for the Fe compounds, the magnetic properties are mainly determined by the Fe-Fe interatomic distances and the number of Fe nearest neighbors, whereas for Co and Ni compounds the magnetic properties are determined by the conduction electron transfer from the rare earth to the 3 d band of Co or Ni, The anomalous thermal expansion of Fe compounds and the metamagnetic transition of the Lu compound is explained in terms of the distance dependence. of the interaction energy as proposed by Neel. © 1971, IEEE. All rights reserved