Wear Tests of a Potential Biolubricant for Orthopedic Biopolymers

Most wear testing of orthopedic implant materials is undertaken with dilute bovine serum used as the lubricant. However, dilute bovine serum is different to the synovial fluid in which natural and artificial joints must operate. As part of a search for a lubricant which more closely resembles synovial fluid, a lubricant based on a mixture of sodium alginate and gellan gum, and which aimed to match the rheology of synovial fluid, was produced. It was employed in a wear test of ultra high molecular weight polyethylene pins rubbing against a metallic counterface. The test rig applied multidirectional motion to the test pins and had previously been shown to reproduce clinically relevant wear factors for ultra high molecular weight polyethylene. After 2.4 million cycles (125 km) of sliding in the presence of the new lubricant, a mean wear factor of 0.099 × 10−6 mm3/Nm was measured for the ultra high molecular weight polyethylene pins. This was over an order of magnitude less than when bovine serum was used as a lubricant. In addition, there was evidence of a transfer film on the test plates. Such transfer films are not seen clinically. The search for a lubricant more closely matching synovial fluid continues

Chamber Structure and Wallcrossing in the ADHM Theory of Curves II

This is the second part of a project concerning variation of stability and chamber structure for ADHM invariants of curves. Wallcrossing formulas for such invariants are derived using the theory of stack function Ringel-Hall algebras constructed by Joyce and the theory of generalized Donaldson-Thomas invariants of Joyce and Song. Some applications are presented, including strong rationality for local stable pair invariants of higher genus curves and comparison with wallcrossing formulas of Kontsevich and Soibelman, and the halo formula of Denef and Moore.Comment: 32 pages, AMS LaTex; v.2: Thm 1.2 improved; v3: many proofs simplified based on a remark of Dominic Joyce, results unchanged; v3: 18 pages, shorter version to appear in J Geom Phy

Midwifery basics. Infant feeding: Managing baby related challenges

Infant feeding: is the twelfth series of ‘Midwifery basics’ targeted at practising midwives. It aims to provide information to raise awareness of the impact of the work of midwives on women’s experience and encourage midwives to seek further information through a series of activities. In this fifth article Joyce Marshall considers a range of baby related issues that pose challenges for both mothers and midwives in relation to infant feeding

Complex solutions of Monge-Amp\`ere equations

We describe a method to reduce partial differential equations of Monge-Amp\`ere type in 4 variables to complex partial differential equations in 2 variables. To illustrate this method, we construct explicit holomorphic solutions of the special lagrangian equation, the real Monge-Amp\`ere equations and the Plebanski equations.Comment: 16 pages, 5 tables To appear in Journal of Geometry and Physic

Does therapeutic massage support mental well-being?

Massage was once a traditional medical practice of many ancient cultures. Today, the practice of modern therapeutic massage is embedded within the field of complementary or alternative medicine (CAM). The demand for evidence based medicine requires the integration of clinical expertise with the best available external evidence from systematic research. Thus in the last twenty years the therapeutic uses of massage have broadened and research has sought to investigate its physical, physiological and psychological effects. This paper reviews the literature in order to determine whether massage is an effective CAM modality that contributes positively to mental wellbeing. The evidence suggests that massage therapy is a relatively safe intervention with no significant adverse effects being reported

Singularities of special Lagrangian submanifolds

We survey what is known about singularities of special Lagrangian submanifolds (SL $m$-folds) in (almost) Calabi-Yau manifolds. The bulk of the paper summarizes the author's work [18-22] on SL $m$-folds $X$ with isolated conical singularities. That is, near each singular point $x$, $X$ is modelled on an SL cone $C$ in $\mathbb{C}^m$ with isolated singularities at 0. We also discuss directions for future research, and give a list of open problems

Compact manifolds with exceptional holonomy

In the classification of Riemannian holonomy groups, the exceptional holonomy groups are G2 in 7 dimensions, and Spin(7) in 8 dimensions. We outline the construction of the first known examples of compact 7- and 8-manifolds with holonomy G2 and Spin(7)