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

Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.

/pdf/climate-change-2007-the-physical-science-basis-1x93ttz9jt.pdf

Climate Change 2007: The Physical Science Basis.

Drafting Authors: Neil Adger, Pramod Aggarwal, Shardul Agrawala, Joseph Alcamo, Abdelkader Allali, Oleg Anisimov, Nigel Arnell, Michel Boko, Osvaldo Canziani, Timothy Carter, Gino Casassa, Ulisses Confalonieri, Rex Victor Cruz, Edmundo de Alba Alcaraz, William Easterling, Christopher Field, Andreas Fischlin, Blair Fitzharris, Carlos Gay García, Clair Hanson, Hideo Harasawa, Kevin Hennessy, Saleemul Huq, Roger Jones, Lucka Kajfež Bogataj, David Karoly, Richard Klein, Zbigniew Kundzewicz, Murari Lal, Rodel Lasco, Geoff Love, Xianfu Lu, Graciela Magrín, Luis José Mata, Roger McLean, Bettina Menne, Guy Midgley, Nobuo Mimura, Monirul Qader Mirza, José Moreno, Linda Mortsch, Isabelle Niang-Diop, Robert Nicholls, Béla Nováky, Leonard Nurse, Anthony Nyong, Michael Oppenheimer, Jean Palutikof, Martin Parry, Anand Patwardhan, Patricia Romero Lankao, Cynthia Rosenzweig, Stephen Schneider, Serguei Semenov, Joel Smith, John Stone, Jean-Pascal van Ypersele, David Vaughan, Coleen Vogel, Thomas Wilbanks, Poh Poh Wong, Shaohong Wu, Gary Yohe

Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change

The purpose of this paper is to provide a comprehensive presentation and interpretation of the Ensemble Kalman Filter (EnKF) and its numerical implementation. The EnKF has a large user group, and numerous publications have discussed applications and theoretical aspects of it. This paper reviews the important results from these studies and also presents new ideas and alternative interpretations which further explain the success of the EnKF. In addition to providing the theoretical framework needed for using the EnKF, there is also a focus on the algorithmic formulation and optimal numerical implementation. A program listing is given for some of the key subroutines. The paper also touches upon specific issues such as the use of nonlinear measurements, in situ profiles of temperature and salinity, and data which are available with high frequency in time. An ensemble based optimal interpolation (EnOI) scheme is presented as a cost-effective approach which may serve as an alternative to the EnKF in some applications. A fairly extensive discussion is devoted to the use of time correlated model errors and the estimation of model bias.

The Ensemble Kalman Filter: Theoretical formulation and practical implementation

Privileged substructures are of potentially great importance in medicinal chemistry. These scaffolds are characterized by their ability to promiscuously bind to a multitude of receptors through a variety of favorable characteristics. This may include presentation of their substituents in a spatially defined manner and perhaps also the ability to directly bind to the receptor itself, as well as exhibiting promising characteristics to aid bioavailability of the overall molecule. It is believed that some privileged substructures achieve this through the mimicry of common protein surface elements that are responsible for binding, such as β- and gamma;-turns. As a result, these structures represent a promising means by which new lead compounds may be identified.

The combinatorial synthesis of bicyclic privileged structures or privileged substructures

The rise in atmospheric CO2 concentration is regarded as the dominant reason for observed warming since the mid-20th century. Based on the Paris Agreement target, this research designs three conceptual pathways to achieve the warming target of 1.5 °C above the pre-industrial level by using the Fast Ocean Atmosphere Model. The three different scenarios contain one equilibrium experiment (equilibrium, EQ) and two transient experiments (never-exceed pathway, NE; overshoot pathway, OS). Then, we choose a ten year average that achieves 1.5 °C warming to calculate the climatology of the warming situation. Since OS achieves 1.5 °C twice, we obtain four warming situations to explore the response of ocean temperature. In 2100, the global ocean temperature increases over the global region, except the surface of the Southern Ocean. The difference in heat content mainly depends on the cumulative force of CO2 concentration. It is worth pointing out that during the increase in warming, the ocean surface temperature and heat content start to respond in different hemispheres. The weakening of decadal variability in the North Pacific and North Atlantic is robust in all three scenarios. However, there is a tremendous growth in the low-pass ocean surface temperature standard deviation in the Southern Ocean in EQ, which is different to NE and OS, and causes the increase in global mean total standard deviation. The shortening of decadal variability can only be seen from the EQ power spectrum, while NE and OS have similar power spectra with pre-industrial runs. It suggests that all previous studies that use equilibrium experiments data may have overestimated the shortening of decadal variability under global warming.

/pdf/change-of-global-ocean-temperature-and-decadal-variability-2m04kpmg.pdf

Change of Global Ocean Temperature and Decadal Variability under 1.5 °C Warming in FOAM

Atmospheric CO2 forcing on glacial thermohaline and climate

The effect of continental slope on buoyancy-driven circulation has been studied using a two-layer quasigeostrophic model. In the model, buoyancy flux is incorporated as interfacial mass flux, which consists of narrow intense detrainment in the north and broad entrainment in the south. The model explicitly shows that, in the presence of the continental slope, a small amount of buoyancy flux can drive a strong barotropic flow. This flow develops because the beta effect of bottom topography either reduces or deflects the buoyancy-driven deep flow so that it cannot compensate its overlying counterflow, thus generating a net transport. As a result, in a double gyre circulation with a western continental slope, a small amount of detrainment/entrainment water mass can substantially enhance the transport of the western boundary current through southwestern deflection of the deep subpolar circulation. For example, with a reasonable western continental slope, a 10 Sv (Sv ≡ 106 m3 s−1) detrainment mass flux...

/pdf/the-effect-of-continental-slope-on-buoyancy-driven-367rkmpgkn.pdf

The Effect of Continental Slope on Buoyancy-Driven Circulation

. The responses of El Nino-Southern Oscillation (ENSO) and the equatorial Pacific annual cycle to external forcing changes are studied in three 3,000-year-long NCAR-CCSM3 model simulations. The simulations represent the period from 300 thousand years before present (ka BP) to present day. The first idealized simulation is forced only with accelerated orbital variations, and the rest are conducted more realistically by further adding on the time-varying boundary conditions of greenhouse gases (GHGs) and continental ice sheets. It is found that orbital forcing dominates slow ENSO evolution, while the effects of GHGs and ice-sheet forcing tend to compensate each other. On the orbital time scales, ENSO variability and annual cycle amplitude change in-phase and both have pronounced precessional cycles (~ 21,000 years) modulated by variations of eccentricity. Orbital forced ENSO intensity is dominated linearly by the change of the coupled ocean-atmosphere instability, notably the Ekman upwelling feedback and the thermocline feedback; and is also possibly affected during ENSO intrinsic developing season by the remote (or extratropical) influences of the short-scale stochastic weather noises. The acceleration technique is found to dampen the precessional signal in ENSO intensity. In glacial-interglacial cycles, additionally, the weakening/strengthening of ENSO owning to a more concentrated/depleted GHGs level leaves little net signal as compensated by the effect coherent change of decaying/expanding ice sheets. They influence the ENSO variability through changes in annual cycle amplitude via a common nonlinear frequency entrainment mechanism while the GHGs effect might has an additional linear part.

/pdf/evolution-and-forcing-mechanisms-of-enso-over-the-last-300-ry9f5yy3gx.pdf

Evolution and forcing mechanisms of ENSO over the last 300,000 years in CCSM3

Penetration of interannual planetary waves across a gyre boundary

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