Pollen content study of the lower atmosphere in León (Spain) by use of a tethered balloon

This study was undertaken in order to understand thebehaviour of airborne pollen grains, namely therelationship between their concentrations andconcomitant meteorological parameters, at differentaltitudes (ground level, 200, 400 and 600 m) of thelower atmosphere and its daily variations over onesite (the experimental farm of the University ofLeón). The experimental design involved a tetheredballoon (2.25 m³), an ADAS remote meteorologicalstation and an original radio controlled three headedpollen and spore sampler (called GABIS) using theRotorod design. Each head sampled a differentaltitude, while two control samples were taken atground level. Twenty-one takeoffs could be realized inthe 5 weeks period between end of May and end of June1997. Sampling was done early in the morning and sampling time at each altitudewas of 15 minutes. Results show that 45 differenttypes of pollen grains could be collected at this timeof the year and that significant variations could beobserved in the behaviour of the pollen cloud on a dayto day basis, probably because of differentmeteorological situations. Contrary to what isgenerally believed, pollen was in most cases moreabundant at higher altitude – on average by 30% ascompared to ground level – making evident anaerobiological layer of transport at about 500 m aboveground. This was especially the case for trees (Quercus and Castanea). The atmosphere MixingRatio was the most explicative factor at 200 m, whiletemperature dominated significance analysis at both400 and 600 m.     

Prediction of the preservation of freeze-dried cucumber mosaic virus

A mathematical model to predict the outcome of preserving plant viruses has been developed. The survival of two cucumber mosaic virus strains lyophilized in leaves and in protected plant sap was evaluated using an accelerated storage test at 28, 37 and 45°C. The combinations of 5% (w/v) sorbitol and 7% (w/v) glucose with 3.6% (w/v) dextran 40000 were applied as protecting media. The predicted values to a great extent correspond to the experimental data, achieved after 1, 4 and 7 years of storage.     

基于NOAA PAL数据集的地表蒸散遥感估算方法

基于NOAA AVHRR气象卫星长时间序列10 d合成的PAL数据集（分辨率8 km×8 km）以及地表能量平衡原理和“VI-T_s”方法,建立了地表蒸散的遥感估算方法,该方法不需要地面气象观测数据的支持,所需参数可直接从遥感数据反演或推算,并选择国际上著名的遥感蒸散模型——SEBS模型对新建模型进行了验证比较.结果表明：新建模型和SEBS模型模拟的地表蒸散值及其季节性变化趋势非常一致,说明新构建模型的模拟结果比较可靠,能够反映地表蒸散的实际情况.新建地表蒸散遥感估算模型可操作性强,为利用长时间序列的卫星遥感数据研究我国乃至全球地表蒸散的时空变化规律提供了一个新的途径.     

Normal‐mode‐based modeling of allosteric couplings that underlie cyclic conformational transition in F1 ATPase

F₁ ATPase, a rotary motor comprised of a central stalk ( γ subunit) enclosed by three α and β subunits alternately arranged in a hexamer, features highly cooperative binding and hydrolysis of ATP. Despite steady progress in biophysical, biochemical, and computational studies of this fascinating motor, the structural basis for cooperative ATPase involving its three catalytic sites remains not fully understood. To illuminate this key mechanistic puzzle, we have employed a coarse‐grained elastic network model to probe the allosteric couplings underlying the cyclic conformational transition in F₁ ATPase at a residue level of detail. We will elucidate how ATP binding and product (ADP and phosphate) release at two catalytic sites are coupled with the rotation of γ subunit via various domain motions in α ₃ β ₃ hexamer (including intrasubunit hinge‐bending motions in β subunits and intersubunit rigid‐body rotations between adjacent α and β subunits). To this end, we have used a normal‐mode‐based correlation analysis to quantify the allosteric couplings of these domain motions to local motions at catalytic sites and the rotation of γ subunit. We have then identified key amino acid residues involved in the above couplings, some of which have been validated against past studies of mutated and γ ‐truncated F₁ ATPase. Our finding strongly supports a binding change mechanism where ATP binding to the empty catalytic site triggers a series of intra‐ and intersubunit domain motions leading to ATP hydrolysis and product release at the other two closed catalytic sites. Proteins 2009. © 2009 Wiley‐Liss, Inc.     

林地叶面积指数遥感估算方法适用分析

叶面积指数是与森林冠层能量和CO2交换密切相关的一个重要植被结构参数,为了探讨估算林地叶面积指数LAI的遥感适用方法和提高精度的途径,利用TRAC仪器测定北京城区森林样地的LAI,从Landsat TM遥感图像计算NDVI、SR、RSR、SAVI植被指数,分别建立估算LAI的单植被指数统计模型、多植被指数组合的改进BP神经网络,获取最有效描述LAI与植被指数非线性关系的方法并应用到TM图像估算北京城区LAI。结果表明,单植被指数非线性统计模型估算LAI的精度高于线性统计模型;多植被指数组合神经网络中,以NDVI、RSR、SAVI组合估算LAI的精度最高,估算值与观测值线性回归方程的R2最高,为0.827,而RMSE最低,为0.189,神经网络解决了多植被指数组合统计模型非线性回归方程的系数较多、较难确定的问题,可较为有效的应用于遥感图像林地LAI的估算。     

Modelling the vegetation of China using the process-based equilibrium terrestrial biosphere model BIOME3

1 We model the potential vegetation and annual net primary production (NPP) of China on a 10′ grid under the present climate using the processed‐based equilibrium terrestrial biosphere model BIOME3. The simulated distribution of the vegetation was in general in good agreement with the potential natural vegetation based on a numerical comparison between the two maps using the ΔV statistic (ΔV = 0.23). Predicted and measured NPP were also similar, especially in terms of biome‐averages. 2 A coupled ocean–atmosphere general circulation model including sulphate aerosols was used to drive a double greenhouse gas scenario for 2070–2099. Simulated vegetation maps from two different CO₂ scenarios (340 and 500 p.p.m.v.) were compared to the baseline biome map using ΔV. Climate change alone produced a large reduction in desert, alpine tundra and ice/polar desert, and a general pole‐ward shift of the boreal, temperate deciduous, warm–temperate evergreen and tropical forest belts, a decline in boreal deciduous forest and the appearance of tropical deciduous forest. The inclusion of CO₂ physiological effects led to a marked decrease in moist savannas and desert, a general decrease for grasslands and steppe, and disappearance of xeric woodland/scrub. Temperate deciduous broadleaved forest, however, shifted north to occupy nearly half the area of previously temperate mixed forest. 3 The impact of climate change and increasing CO₂ is not only on biogeography, but also on potential NPP. The NPP values for most of the biomes in the scenarios with CO₂ set at 340 p.p.m.v. and 500 p.p.m.v. are greater than those under the current climate, except for the temperate deciduous forest, temperate evergreen broadleaved forest, tropical rain forest, tropical seasonal forest, and xeric woodland/scrub biomes. Total vegetation and total carbon is simulated to increase significantly in the future climate scenario, both with and without the CO₂ direct physiological effect. 4 Our results show that the global process‐based equilibrium terrestrial biosphere model BIOME3 can be used successfully at a regional scale.     

A mechanistic model on the role of “radially-running” collagen fibers on dissection properties of human ascending thoracic aorta

Aortic dissection (AoD) is a common condition that often leads to life-threatening cardiovascular emergency. From a biomechanics viewpoint, AoD involves failure of load-bearing microstructural components of the aortic wall, mainly elastin and collagen fibers. Delamination strength of the aortic wall depends on the load-bearing capacity and local micro-architecture of these fibers, which may vary with age, disease and aortic location. Therefore, quantifying the role of fiber micro-architecture on the delamination strength of the aortic wall may lead to improved understanding of AoD. We present an experimentally-driven modeling paradigm towards this goal. Specifically, we utilize collagen fiber micro-architecture, obtained in a parallel study from multi-photon microscopy, in a predictive mechanistic framework to characterize the delamination strength. We then validate our model against peel test experiments on human aortic strips and utilize the model to predict the delamination strength of separate aortic strips and compare with experimental findings. We observe that the number density and failure energy of the radially-running collagen fibers control the peel strength. Furthermore, our model suggests that the lower delamination strength previously found for the circumferential direction in human aorta is related to a lower number density of radially-running collagen fibers in that direction. Our model sets the stage for an expanded future study that could predict AoD propagation in patient-specific aortic geometries and better understand factors that may influence propensity for occurrence.     

Caffeine-induced Ca2+ oscillations in type I horizontal cell of carp retina: A mathematical model

Oscillations in intracellular free Ca²⁺ concentration ([Ca²⁺]_i) have been observed in a variety of cell types. In the present study, we constructed a mathematical model to simulate the caffeine-induced [Ca²⁺]_i oscillations based on experimental data obtained from isolated type I horizontal cell of carp retina. The results of model analysis confirm the notion that the caffeine-induced [Ca²⁺]_i oscillations involve a number of cytoplasmic and endoplasmic Ca²⁺ processes that interact with each other. Using this model, we evaluated the importance of store-operated channel (SOC) in caffeine-induced [Ca²⁺]_i oscillations. The model suggests that store-operated Ca²⁺ entry (SOCE) is elicited upon depletion of the endoplasmic reticulum (ER). When the SOC conductance is set to 0, caffeine-induced [Ca²⁺]_i oscillations are abolished, which agrees with the experimental observation that [Ca²⁺]_i oscillations were abolished when SOC was blocked pharmacologically, verifying that SOC is necessary for sustained [Ca²⁺]_i oscillations.