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

The manipulation of fluids in channels with dimensions of tens of micrometres--microfluidics--has emerged as a distinct new field. Microfluidics has the potential to influence subject areas from chemical synthesis and biological analysis to optics and information technology. But the field is still at an early stage of development. Even as the basic science and technological demonstrations develop, other problems must be addressed: choosing and focusing on initial applications, and developing strategies to complete the cycle of development, including commercialization. The solutions to these problems will require imagination and ingenuity.

The origins and the future of microfluidics

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Self-assembled monolayers of thiolates on metals as a form of nanotechnology.

Self-assembly is the autonomous organization of components into patterns or structures without human intervention. Self-assembling processes are common throughout nature and technology. They involve components from the molecular (crystals) to the planetary (weather systems) scale and many different kinds of interactions. The concept of self-assembly is used increasingly in many disciplines, with a different flavor and emphasis in each.

http://science.sciencemag.org/content/sci/295/5564/2418.full.pdf

Self-assembly at all scales.

Modeling the dynamics of remobilized CO2 within the geologic subsurface

Irrigation takes considerable amount of water; however, in many cases up to half of it is wasted. Improving the efficiency of irrigation control, therefore, is an important task for sustainable water management. Most existing irrigation control systems are based on soil moisture level. In this work, we explore theoretically the use of continuous values stem water potential (SWP) as a basis for control. SWP is a more direct measure of plant water status than the soil moisture level. After linearizing and discretizing a nonlinear dynamic model of water dynamics in a plant, we develop a model predictive control (MPC) framework for regulating SWP. To prevent plants from suffering water stress, data-driven robust MPC (DDRMPC) which captures the uncertainty of weather forecast error is implemented. A case study based on almond tree is presented to characterize the effectiveness of the DDRMPC strategy relative to on-off control. Sensitivity analysis on the prediction horizon and penalty weights were performed to investigate the varying irrigation control decisions. For the case characterized, the analysis shows that controlling tree trunk water potential through DDRMPC can save 2.5% amount of water comparing to on-off control while maintaining zero violation.

Theoretical Exploration of Irrigation Control for Stem Water Potential through Model Predictive Control

We consider laminar flow in channels constrained geometrically to remain between two parallel planes; this geometry is typical of microchannels obtained with a single step by current microfabrication techniques. For pressure-driven Stokes flow in this geometry and assuming that the channel dimensions change slowly in the streamwise direction, we show that the velocity component perpendicular to the constraint plane cannot be zero unless the channel has both constant curvature and constant cross-sectional width. This result implies that it is, in principle, possible to design "planar mixers", i.e. passive mixers for channels that are constrained to lie in a flat layer using only streamwise variations of their in-plane dimensions. Numerical results are presented for the case of a channel with sinusoidally varying width.

http://arxiv.org/pdf/cond-mat/0306572.pdf

Three-dimensional flows in slowly-varying planar geometries

We investigate the filling and emptying of extreme ink-bottle porous media—micrometer-scale pores connected by nanometer-scale pores—when changing the pressure of the external vapor, in a case where the pore liquid contains solutes. These phenomena are relevant in diverse contexts, such as the weathering of building materials and artwork, aerosol formation in the atmosphere, and the hydration of soils and plants. Using model systems made of vein-shaped microcavities interconnected by a mesoporous matrix, we show experimentally that the presence of a nonvolatile solute shifts the condensation and evaporation transitions and in a way that is consistent with a modified Kelvin–Laplace equation that takes into account the osmotic pressure of the solution. Emptying occurs far below saturation, when the Kelvin stress, mediated by the large curvature of the liquid–vapor interfaces in the nanopores, is negative enough to induce spontaneous bubble nucleation in the microveins. Filling, on the other hand, occurs clo...

/pdf/how-solutes-modify-the-thermodynamics-and-dynamics-of-pv1dxhjqqp.pdf

How Solutes Modify the Thermodynamics and Dynamics of Filling and Emptying in Extreme Ink-Bottle Pores.

Although visual and olfactory floral signals attract pollinators from a distance, at the flower’s threshold, pollinators can use floral humidity as an index cue for nectar presence. We evaluate the role of floral humidity in the Datura wrightii-Manduca sexta nocturnal pollination system. In addition to our finding that M. sexta shows strong innate attraction toward humid flowers, we identify the hygrosensing sensillum on their antennae, demonstrate its extreme sensitivity to minute changes in RH, and observe the elimination of moths’ behavioral preference towards humid flowers following experimental occlusion of the sensilla. Despite Manduca’s attraction toward humid flowers, we find that floral humidity is not a reliable cue for nectar presence in this system. While Datura floral headspace sustains an enormous humidity gradient, it is not a consequence of nectar evaporation, but an outcome of gas exchange through floral stomata and is decoupled from nectar presence. Using interdisciplinary tools, we demonstrate the function of floral humidity as an attractive signal, not a cue, in this pollination system, thus showcasing an underappreciated modality by which flowers may manipulate their visitors.

Abraham D. Stroock

Papers

Modeling the dynamics of remobilized CO2 within the geologic subsurface

Theoretical Exploration of Irrigation Control for Stem Water Potential through Model Predictive Control

Three-dimensional flows in slowly-varying planar geometries

How Solutes Modify the Thermodynamics and Dynamics of Filling and Emptying in Extreme Ink-Bottle Pores.

Floral humidity as a signal – not a cue – in a nocturnal pollination system