Determining the equilibrium configuration of an elastic Möbius band is a challenging problem. In recent years numerical results have been obtained by other investigators, employing first the Kirchhoff theory of rods and later the developable, ruledsurface model of Wunderlich. In particular, the strategy employed previously for the latter does not deliver an unconstrained equilibrium configuration for the complete strip. Here we present our own systematic approach to the same problem for each of these models, with the ultimate goal of assessing the stability of flip-symmetric configurations. The presence of pointwise constraints considerably complicates the latter step. We obtain the first stability results for the problem, numerically demonstrating that such equilibria render the total potential energy a local minimum. Along the way we introduce a novel regularization for the for the singular Wunderlich model that delivers unconstrained equilibria for the complete strip, which can then be tested for stability.

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GaAs-based lasers were bonded to oxygen-free high-conductivity (OFHC) copper heat sinks using a eutectic PbSn solder or a silver-filled conductive epoxy, and life tested. Epoxy-bonded devices were observed to have a larger failure rate on life test than solder-bonded devices. Bonding stress, as measured by the degree of polarization (DOP) of photoluminescence, was found to be the largest in epoxy-bonded devices. As well, the type of heat sink and bonding adhesive affected the stress in the laser material, with bonding stress increasing when there was a larger mismatch of coefficients of thermal expansion between the laser material, adhesive, and heat sink. Results suggested that heat sink material and bonding adhesive contribute to stress within the laser material and the resulting performance of the device.

SUMMARYA 66-year-old man presented with a large squamous cell carcinoma of the right nasal vestibule. He underwent partial rhinectomy and medial maxillectomy followed by staged reconstruction. Reconstruction of a full-thickness nasal defect requires repair of three distinct layers: the skin-soft tissue envelope, subsurface framework and intranasal lining. We report the first use in the UK of an osteocutaneous radial forearm free flap in the reconstruction of a subtotal nasal deficit. The skin of the radial forearm free flap was tubed to recreate the nasal lining and the radial bone reconstructed the dorsal contour of the nose. A full-thickness paramedian forehead flap supplied external coverage. The osteocutaneous radial forearm free flap and forehead flap is a viable option for large nasal defects requiring reconstruction of framework, nasal lining and external covering. BACKGROUND

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