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

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Bose-Einstein condensation (BEC) has been observed in a dilute gas of sodium atoms. A Bose-Einstein condensate consists of a macroscopic population of the ground state of the system, and is a coherent state of matter. In an ideal gas, this phase transition is purely quantum-statistical. The study of BEC in weakly interacting systems which can be controlled and observed with precision holds the promise of revealing new macroscopic quantum phenomena that can be understood from first principles.

Bose-Einstein condensation in a gas of sodium atoms

Evolutionary games on graphs

2. GRAVITY 7. MICROSCOPIC PHYSICS 13. TOPOLOGY OF DEFECTS 18. ANOMALOUS NON-CONSERVATION OF FERMIONIC CHARGE 22. EDGE STATES AND FERMION ZERO MODES ON SOLITON 26. LANDAU CRITICAL VELOCITY 29. CASIMIR EFFECT AND VACUUM ENERGY

The Universe in a Helium Droplet

TOPOLOGICAL defects in the geometry of space–time (such as cosmic strings) may have played an important role in the evolution of the early Universe, by supplying initial density fluctuations which seeded the clusters of galaxies that we see today1. The formation of cosmic strings during a symmetry-breaking phase transition shortly after the Big Bang is analogous to vortex creation in liquid helium following a rapid transition into the superfluid state; the underlying physics of this cosmological defect-forming process (known as the Kibble mechanism1) should therefore be accessible to experimental study. Superfluid vortices have been observed in 4He following rapid quenching to the superfluid state2, lending qualitative support to Kibble's contention that topological defects are generated by such phase transitions. Here we quantify this process by using an exothermic neutron-induced nuclear reaction to heat small volumes of super-fluid 3He above the superfluid transition temperature, and then measuring the deficit in energy released as these regions of normal liquid pass back into the superfluid state. By ascribing this deficit to the formation of a tangle of vortices, we are able to infer the resulting vortex density; we find that this agrees very well with the predictions of Zurek's modification3 of the original Kibble mechanism1.

Laboratory simulation of cosmic string formation in the early Universe using superfluid 3He

Rotating superfluid helium-3 produces vortices, much like water disappearing down a plughole, but these vortices are governed by quantum mechanics. A new type of quantum vortex has been created in helium-3 that may be the superfluid analogue of cosmic strings (vortices in the structure of space-time).

Superfluidity. A new twist to an old story

We describe the first direct observations of turbulence in super-fluid He-3-B. The turbulence is generated by a vibrating-wire resonator driven at velocities exceeding the pair-breaking critical velocity. It is detected by the resulting decrease in the thermal damping on a neighboring "detector" vibrating-wire resonator. The superfluid flow field associated with the turbulence Andreev reflects thermal quasiparticle excitations, effectively screening the detector wire, resulting in a decrease in the thermal damping.

Generation and Detection of Quantum Turbulence in Superfluid 3He-B

We describe measurements of the decay of pure superfluid turbulence in superfluid He-3-B, in the low temperature regime where the normal fluid density is negligible. We follow the decay of the turbulence generated by a vibrating grid as detected by vibrating wire resonators. Despite the absence of any classical normal fluid dissipation processes, the decay is consistent with turbulence having the classical Kolmogorov energy spectrum and is remarkably similar to that measured in superfluid He-4 at relatively high temperatures. Further, our results strongly suggest that the decay is governed by the superfluid circulation quantum rather than kinematic viscosity.

Decay of pure quantum turbulence in superfluid 3He-B.

An experimental procedure is described for the characterization of the response of very small vibrating wires to liquid3He at temperatures down to 120 µK. The relative scales of the mean free path in the liquid and the radius of the wire play a significant role in the interpretation of the results. It is shown that the same ideas concerning the transition from hydrodynamic to ballistic behavior as the temperature is reduced can be applied both to saturated3He-4He solutions and to superfluid3He-B.

George R. Pickett

Papers

Laboratory simulation of cosmic string formation in the early Universe using superfluid 3He

Superfluidity. A new twist to an old story

Generation and Detection of Quantum Turbulence in Superfluid 3He-B

Decay of pure quantum turbulence in superfluid 3He-B.

The mechanical behavior of a vibrating wire in superfluid 3 He-B in the ballistic limit