山东海域赤潮灾害特征及预警报管理

掌握赤潮灾害时空分布规律是科学设计赤潮监控方案、提高防灾管理效率的基础和依据。本文统计分析了1990—2010年间山东海域的76次赤潮灾害事件数据。结果表明:赤潮灾害频率显著地分为4个波段,且峰值呈递增趋势;灾害面积呈现周期性倒U型曲线变化;每年的5—10月是赤潮灾害的多发期,其中,8月的灾害次数和灾害面积均占全年总数的30%以上;灾害空间分布集中在莱州湾海域、青岛近海、庙岛群岛的北隍城海域,烟台四十里湾的赤潮灾害最频繁;夜光藻(Noctiluca scintillans)和球型棕囊藻(Phaeocystis globosa)引发的赤潮灾害面积最高,夜光藻和红色裸甲藻(Gymnodinium sanguineum)致灾次数最多。本文从赤潮监测与信息采集、赤潮预报方法以及赤潮灾害预警报管理机制3个方面分析总结了山东海域赤潮灾害预警报业务化管理现状,结合山东海域赤潮灾害特征和预警报管理实践,提出了以控制污染和修复生态环境为根本的赤潮防控建议。     

Projected impacts of climate change on spatio‐temporal patterns of freshwater fish beta diversity: a deconstructing approach

Aim To assess the potential impacts of future climate change on spatio‐temporal patterns of freshwater fish beta diversity. Location Adour–Garonne River Basin (France). Methods We first applied an ensemble modelling approach to project annually the future distribution of 18 fish species for the 2010–2100 period on 50 sites. We then explored the spatial and temporal patterns of beta diversity by distinguishing between its two additive components, namely species turnover and nestedness. Results Taxonomic homogenization of fish assemblages was projected to increase linearly over the 21st century, especially in the downstream parts of the river gradient. This homogenization process was almost entirely caused by a decrease in spatial species turnover. When considering the temporal dimension of beta diversity, our results reveal an overall pattern of decreasing beta diversity along the upstream–downstream river gradient. In contrast, when considering the turnover and nestedness components of temporal beta diversity we found significant U‐shaped and hump‐shaped relationships, respectively. Main conclusions Future climate change is projected to modify the taxonomic composition of freshwater fish assemblages by increasing their overall similarity over the Adour–Garonne River Basin. Our findings suggest that the distinction between the nestedness and turnover components of beta diversity is not only crucial for understanding the processes shaping spatial beta‐diversity patterns but also for identifying localities where the rates of species replacement are projected to be greatest. Specifically we recommend that future conservation studies should not only consider the spatial component of beta diversity but also its dynamic caused by climate warming.     

农作物产量预报模型研究与实践

选取玉米、大豆、小麦三种作物,建立产量的定性和定量预报模型,即年景趋势预报模型、逐步回归周期分量预报模型和多层递阶预报模型。经过检验和预报实践检验,表明所得到的预测模型具有一定的实用价值。     

Backbone dynamics of the cytotoxic ribonuclease alpha-sarcin by 15N NMR relaxation methods

The cytotoxic ribonuclease -sarcin is a 150-residue protein that inactivates ribosomes by selectively cleaving a single phosphodiester bond in a strictly conserved rRNA loop. In order to gain insights on the molecular basis of its highly specific activity, we have previously determined its solution structure and studied its electrostatics properties. Here, we complement those studies by analysing the backbone dynamics of -sarcin through measurement of longitudinal relaxation rates R₁, off resonance rotating frame relaxation rates R₁, and the ¹⁵N¹HNOE of the backbone amide ¹⁵N nuclei at two different magnetic field strengths (11.7 and 17.6 T). The two sets of relaxation parameters have been analysed in terms of the reduced spectral density mapping formalism, as well as by the model-free approach. -Sarcin behaves as an axial symmetric rotor of the prolate type (D/D=1.16 ± 0.02) which tumbles with a correlation time _m of 7.54 ± 0.02 ns. The rotational diffusion properties have been also independently evaluated by hydrodynamic calculations and are in good agreement with the experimental results. The analysis of the internal dynamics reveals that -sarcin is composed of a rigid hydrophobic core and some exposed segments which undergo fast (ps to ns) internal motions. Slower motions in the s to ms time scale are less abundant and in some cases can be assigned to specific motional processes. All dynamic data are discussed in relation to the role of some particular residues of -sarcin in the process of recognition of its ribosomal target.     

Efron-type measures of prediction error for survival analysis

Estimates of the prediction error play an important role in the development of statistical methods and models, and in their applications. We adapt the resampling tools of Efron and Tibshirani (1997, Journal of the American Statistical Association92, 548-560) to survival analysis with right-censored event times. We find that flexible rules, like artificial neural nets, classification and regression trees, or regression splines can be assessed, and compared to less flexible rules in the same data where they are developed. The methods are illustrated with data from a breast cancer trial.     

Accuracy and precision of NMR relaxation experiments and MD simulations for characterizing protein dynamics

Model-free parameters obtained from nuclear magnetic resonance (NMR) relaxation experiments and molecular dynamics (MD) simulations commonly are used to describe the intramolecular dynamical properties of proteins. To assess the relative accuracy and precision of experimental and simulated model-free parameters, three independent data sets derived from backbone ¹⁵N NMR relaxation experiments and two independent data sets derived from MD simulations of Escherichia coli ribonuclease HI are compared. The widths of the distributions of the differences between the order parameters for pairs of NMR data sets are congruent with the uncertainties derived from statistical analyses of individual data sets; thus, current protocols for analyzing NMR data encapsulate random uncertainties appropriately. Large differences in order parameters for certain residues are attributed to systematic differences between samples for intralaboratory comparisons and unknown, possibly magnetic field-dependent, experimental effects for interlaboratory comparisons. The widths of distributions of the differences between the order parameters for two NMR sets are similar to widths of distributions for an NMR and an MD set or for two MD sets. The linear correlations between the order parameters for an MD set and an NMR set are within the range of correlations observed between pairs of NMR sets. These comparisons suggest that the NMR and MD generalized order parameters for the backbone amide N—H bond vectors are of comparable accuracy for residues exhibiting motions on a fast time scale (<100 ps). Large discrepancies between NMR and MD order parameters for certain residues are attributed to the occurrence of “rare” motional events over the simulation trajectories, the disruption of an element of secondary structure in one of the simulations, and lack of consensus among the experimental data sets. Consequently, (easily detectable) severe distortions of local protein structure and infrequent motional events in MD simulations appear to be the most serious artifacts affecting the accuracy and precision, respectively, of MD order parameters relative to NMR values. In addition, MD order parameters for motions on a fast (<100 ps) timescale are more precisely determined than their NMR counterparts, thereby permitting more detailed dynamic characterization of biologically important residues by MD simulation than is sometimes possible by experimental methods. Proteins 28:481–493, 1997. © 1997 Wiley-Liss, Inc.     

基于LAI的东亚飞蝗发生面积的预测模型

20世纪80年代以来东亚飞蝗在我国再度猖獗危害,及时、准确地监测东亚飞蝗的危害状况,对于东亚飞蝗的有效防治有重要意义.以河北省黄骅市为研究区,从光学模型的建立机理为着眼点,定量分析和对比了4种由植被冠层孔隙度反演LAI的算法.结果表明,LAI与植被指数之间呈明显的正相关关系,即随着LAI的增大,植被指数也在增大;在4种估算方法中,LAI-2000算法最适用于研究区植被LAI的估算.此外,还分析了LAI与飞蝗发生面积的关系,发现两者呈负相关.并在此基础上建立了飞蝗发生面积的预测模型,即：ALO=-aln（LAI）＋b,其中,a、b为调节系数.