抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

to be done in this area. Face recognition is a problem that scarcely clamoured for attention before the computer age but, having surfaced, has involved a wide range of techniques and has attracted the attention of some fine minds (David Mumford was a Fields Medallist in 1974). This singular application of mathematical modelling to a messy applied problem of obvious utility and importance but with no unique solution is a pretty one to share with students: perhaps, returning to the source of our opening quotation, we may invert Duncan's earlier observation, 'There is an art to find the mind's construction in the face!'.

Linear and nonlinear waves, by G. B. Whitham. Pp.636. £50. 1999. ISBN 0 471 35942 4 (Wiley).

To say that this is the best book on the quantum theory of fields is no praise, since to my knowledge it is the only book on this subject But it is a very good and most useful book The original was written in German and appeared in 1942 This is a translation with some minor changes A few remarks have been added, concerning meson theory and nuclear forces, also footnotes referring to modern work in this field, and finally an appendix on the symmetrization of the energy momentum tensor according to Belinfante Quantum Theory of Fields Prof Gregor Wentzel Translated from the German by Charlotte Houtermans and J M Jauch Pp ix + 224, (New York and London: Interscience Publishers, Inc, 1949) 36s

Quantum Theory of Fields

There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Handbook of Chemistry and Physics

Water striders (Gerris remigis) have remarkable non-wetting legs that enable them to stand effortlessly and move quickly on water, a feature believed to be due to a surface-tension effect caused by secreted wax. We show here, however, that it is the special hierarchical structure of the legs, which are covered by large numbers of oriented tiny hairs (microsetae) with fine nanogrooves, that is more important in inducing this water resistance.

/pdf/biophysics-water-repellent-legs-of-water-striders-3a4p860uri.pdf

Biophysics: Water-repellent legs of water striders

Spin-up from rest in a stratified fluid

A hydrodynamic analog of the Talbot or self-imaging effect is observed on the surface of a vertically shaken fluid bath when a periodic row of pillars protrudes from the surface. The self-images are used to trap bouncing and walking droplets.

Hydrodynamic analog of particle trapping with the Talbot effect

We examine the spin-up from rest of a stratified fluid with initial Brunt-Vaisalafrequency N bound within a cylindrical container of height 2H and radius R which is set to rotate impulsively with angular speed f/2. Particular attention is given to characterizing the dependence of the form of the resulting flow on the govern- ing parameters. Our experimental study reveals a wealth of flow behaviours and instabilities. In all experi- ments, the initial phase of motion is marked by the establishment of mixed axisymmetric corner regions fed by radial Ekman transport, a process detailed in Flor et al. (Flor, J.B., Ungarish, M. and Bush, J.W.M., ''Spin-up from rest of a stratified fluid: boundary flows'', J. Fluid Mech., 472, 51-82 (2002).). The subsequent evolution of the central vortex depends critically on the Burger number Bcore ¼ NcH=ð fRÞ, where Nc ¼ Nð1 � 0:2B � 1 Þ 1=2 is the buoyancy frequency of the central core following the establishment of the corner regions. For B > 1:0, the axisymmetry of the system is retained throughout the spin-up process: the central vortex attains a state of near solid body rotation by the diffusion of vorticity from the sidewalls. For B 1, the centreline of the stratified core is deflected into a helical form before the core breaks into a series of stacked vortices. A Burger number criterion, B ¼ NH=ð fRÞ < 1:0, for the baroclinic instability of the central core is derived and found to be consistent with the experimental observations.

http://www.legi.grenoble-inp.fr/people/Jan-Bert.Flor/PUBLICATIONS/FBU.pdf

An experimental investigation of spin-up from rest of a stratified fluid

We present the results of a combined experimental and theoretical investigation of the capillary instability of an elastic helical thread bound within a fluid. The influence of the thread's elastic energy on the classic Rayleigh–Plateau instability is elucidated. The most unstable wavelength can be substantially increased by the influence of the helical coil. The relation between our system and the capture thread of the orb-spider is discussed.

Capillary instability on an elastic helix

The motion of a buoyant inviscid drop rising vertically along the rotation axis of a rapidly rotating low viscosity fluid bounded above and below by rigid horizontal boundaries is considered in the case that the drop is circumscribed by a Taylor column that spans the entire fluid depth. Both the shape and steady rise speed of the drop are deduced as a function of the interfacial tension. The analysis demonstrates that the drop assumes the form of the prolate ellipsoidal figure of revolution which would arise in the absence of any relative motion in the surrounding fluid. The hydrodynamic drag on the drop follows simply from the analysis of Moore and Saffman [J. Fluid Mech. 31, 635 (1968)], who considered the equivalent motion of a rigid particle. The rise speed of a deformed inviscid drop is approximately one‐half that of an identically shaped rigid particle; in particular, the rise speed of a spherical inviscid drop is 0.41 that of a rigid sphere.

John W. M. Bush

Papers

Spin-up from rest in a stratified fluid

Hydrodynamic analog of particle trapping with the Talbot effect

An experimental investigation of spin-up from rest of a stratified fluid

Capillary instability on an elastic helix

The motion of an inviscid drop in a bounded rotating fluid