First insights into the biodiversity and biogeography of the Southern Ocean deep sea

Shallow marine benthic communities around Antarctica show high levels of endemism, gigantism, slow growth, longevity and late maturity, as well as adaptive radiations that have generated considerable biodiversity in some taxa. The deeper parts of the Southern Ocean exhibit some unique environmental features, including a very deep continental shelf and a weakly stratified water column, and are the source for much of the deep water in the world ocean. These features suggest that deep-sea faunas around the Antarctic may be related both to adjacent shelf communities and to those in other oceans. Unlike shallow-water Antarctic benthic communities, however, little is known about life in this vast deep-sea region. Here, we report new data from recent sampling expeditions in the deep Weddell Sea and adjacent areas (748-6,348 m water depth) that reveal high levels of new biodiversity; for example, 674 isopods species, of which 585 were new to science. Bathymetric and biogeographic trends varied between taxa. In groups such as the isopods and polychaetes, slope assemblages included species that have invaded from the shelf. In other taxa, the shelf and slope assemblages were more distinct. Abyssal faunas tended to have stronger links to other oceans, particularly the Atlantic, but mainly in taxa with good dispersal capabilities, such as the Foraminifera. The isopods, ostracods and nematodes, which are poor dispersers, include many species currently known only from the Southern Ocean. Our findings challenge suggestions that deep-sea diversity is depressed in the Southern Ocean and provide a basis for exploring the evolutionary significance of the varied biogeographic patterns observed in this remote environment.     

Controls on tropical Pacific Ocean productivity revealed through nutrient stress diagnostics

In situ enrichment experiments have shown that the growth of bloom-forming diatoms in the major high-nitrate low-chlorophyll (HNLC) regions of the world's oceans is limited by the availability of iron. Yet even the largest of these manipulative experiments represents only a small fraction of an ocean basin, and the responses observed are strongly influenced by the proliferation of rare species rather than the growth of naturally dominant populations. Here we link unique fluorescence attributes of phytoplankton to specific physiological responses to nutrient stress, and use these relationships to evaluate the factors that constrain phytoplankton growth in the tropical Pacific Ocean on an unprecedented spatial scale. On the basis of fluorescence measurements taken over 12 years, we delineate three major ecophysiological regimes in this region. We find that iron has a key function in regulating phytoplankton growth in both HNLC and oligotrophic waters near the Equator and further south, whereas nitrogen and zooplankton grazing are the primary factors that regulate biomass production in the north. Application of our findings to the interpretation of satellite chlorophyll fields shows that productivity in the tropical Pacific basin may be 1.2-2.5 Pg C yr(-1) lower than previous estimates have suggested, a difference that is comparable to the global change in ocean production that accompanied the largest El Ni?o to La Ni?a transition on record.     

Oceanic Cd/P ratio and nutrient utilization in the glacial Southern Ocean

During glacial periods, low atmospheric carbon dioxide concentration has been associated with increased oceanic carbon uptake, particularly in the southern oceans. The mechanism involved remains unclear. Because ocean productivity is strongly influenced by nutrient levels, palaeo-oceanographic proxies have been applied to investigate nutrient utilization in surface water across glacial transitions. Here we show that present-day cadmium and phosphorus concentrations in the global oceans can be explained by a chemical fractionation during particle formation, whereby uptake of cadmium occurs in preference to uptake of phosphorus. This allows the reconstruction of past surface water phosphate concentrations from the cadmium/calcium ratio of planktonic foraminifera. Results from the Last Glacial Maximum show similar phosphate utilization in the subantarctic to that of today, but much smaller utilization in the polar Southern Ocean, in a model that is consistent with the expansion of glacial sea ice and which can reconcile all proxy records of polar nutrient utilization. By restricting communication between the ocean and atmosphere, sea ice expansion also provides a mechanism for reduced CO2 release by the Southern Ocean and lower glacial atmospheric CO2.     

马尔可夫时滞网络控制系统的稳定性

针对同时具有马尔可夫(Markov)链跳变特性时滞和随机丢包现象的网络控制系统,建立了网络控制系统的离散模型,利用李亚普诺夫稳定性理论、线性矩阵不等式和自由权矩阵方法,分析了系统的均方稳定性和均方可镇定性,并基于线性不等式给出了系统均方稳定、镇定判据.该方法能判定具有马尔可夫时滞和丢包的网络控制系统的均方稳定性,并设计出同等条件下的均方可镇定时滞依赖控制器.与现有方法相比.能更准确地描述网络时滞特性,有效减小系统保守性,结果更具一般性.最后通过仿真实例证明了方法的有效性.     

Cellular peptide composition governed by major histocompatibility complex class I molecules

Major histocompatibility complex (MHC) class I molecules present peptides derived from cellular proteins to cytotoxic T lymphocytes (CTLs), which check these peptides for abnormal features. How such peptides arise in the cell is not known. Here we show that the MHC molecules themselves are substantially involved in determining which peptides occur intracellularly: normal mouse spleen cells identical at all genes but MHC class I express different patterns of peptides derived from cellular non-MHC proteins. We suggest several models to explain this influence of MHC class I molecules on cellular peptide composition.     

Reduced North Atlantic Deep Water flux to the glacial Southern Ocean inferred from neodymium isotope ratios

The global circulation of the oceans and the atmosphere transports heat around the Earth. Broecker and Denton suggested that changes in the global ocean circulation might have triggered or enhanced the glacial-interglacial cycles. But proxy data for past circulation taken from sediment cores in the South Atlantic Ocean have yielded conflicting interpretations of ocean circulation in glacial times--delta13C variations in benthic foraminifera support the idea of a glacial weakening or shutdown of North Atlantic Deep Water production, whereas other proxies, such as Cd/Ca, Ba/Ca and 231Pa/230Th ratios, show little change from the Last Glacial Maximum to the Holocene epoch. Here we report neodymium isotope ratios from the dispersed Fe-Mn oxide component of two southeast Atlantic sediment cores. Both cores show variations that tend towards North Atlantic signatures during the warm marine isotope stages 1 and 3, whereas for the full glacial stages 2 and 4 they are closer to Pacific Ocean signatures. We conclude that the export of North Atlantic Deep Water to the Southern Ocean has resembled present-day conditions during the warm climate intervals, but was reduced during the cold stages. An increase in biological productivity may explain the various proxy data during the times of reduced North Atlantic Deep Water export.     

安康市辖县县城文化设施适宜性标准研究

目的完善国家标准普适性强而针对性较弱的问题,探索适宜安康市县城的文化设施规划标准。方法运用文献查阅、比较分析、问卷调查和实地调研的方法。结果现有相关规划标准与安康9县文化设施的实际建设相差较大,不能满足规划建设的现实需要,有必要建立针对性较强的适宜性标准,其标准应包含配建体系和相关标准两方面内容,具体包括设施类型、设施规模、服务人口、千人指标等。结论县城文化设施的配置既要满足县城居民的需求,同时也要为县城周边的乡镇和农村地区人口提供相应的公共服务,构建覆盖全县域的城乡文化设施服务体系。     

二阶差分方程边值问题的一个存在定理

运用拓扑度理论获得了如下边值问题Δ2 u(k) +g(k)f(u(k) ) =0 ,　k∈ [0 ,T]u(0 ) =0 =u(T+2 )的一个新的存在定理 ,其中T为固定的正整数     

测度链上分数阶动力方程的最优控制问题

通过给相关函数适当的条件,对于任意给定的控制策略,获得非线性分数阶控制系统唯一解的存在性,并且研究测度链上分数阶动力方程最优控制问题最优解的存在性.     

一类二阶积微分受控系统的最优控制

研究了受控系统为受无界算子扰动的一类二阶非线性积微分方程的控制问题.对一类Lagrange问题(P),证明了最优控制的存在性.     

椭圆方程约束的最优边界控制问题的非重叠型区域分解迭代方法

研究了一类椭圆方程约束的最优边界控制问题的数值求解方法。为了避免运用传统数值方法所产生庞大的计算量,我们采用非重叠型区域分解迭代方法。即:将求解区域Ω分解成若干个非重叠子区域,把上述的最优边界控制问题分解成这些子区域上的局部问题,这些局部问题间的内边界条件采用Robin条件。建立了求解这些局部问题的迭代格式,推导证明了迭代格式的收敛性。最后,给出一个数值算例,验证了迭代格式的有效性。     

种群服从Gompertz增长的数学生物经济模型的定性分析

对种群服从Gompertz增长的开放式生物资源建立了价格随供求而变化的捕获模型,并对其进行了详细分析。讨论了平衡点的存在性、稳定性及极限环的不存在性,从生态学和经济学的角度对所得到的结果做出了解释。探讨了关于生物资源开发的相关问题,为生物资源的实际开发与管理提供了必要的理论依据。     

一类退化半线性椭圆方程支配系统的最优控制条件

研究了一类由退化半线性椭圆方程所支配的分布参数系统的最优控制问题.当退化点集的测度为零时,利用正则化方法和变分思想,得到了该分布参数系统最优控制所满足的必要条件.     

受控系统为一类紧半群非线性发展方程的最优控制

研究无穷维空间中一类紧半群的非线性积微分方程及其对应的最优控制问题。首先，我们讨论对应的积分算子的紧性，给出此类积微分不等式相应Gronwall不等式。进而，证明了此类积微粉方程的温和解局部和全局存在性。最后，给出了相应的Lagrange型最优控制存在的充分条件。     

中等复杂程度全球热带海洋模式模拟的热带印度洋海表温度变率

利用一个中等复杂程度全球热带海洋模式模拟研究了表面强迫异常引起的热带印度洋海表温度(SST)变率．利用1958—1998年表面分析资料作为强迫场，积分海洋模式41年作为控制试验，并利用模式分别做动量(风应力)通量和热量通量无异常变化的平行试验，与控制试验作比较．通过3组试验模拟的上层海洋变率状况的比较，分析了动量和热量通量异常对热带印度洋SST变率的影响，并比较了其影响的相对重要性．结果表明，模拟的热带印度洋SST变率的主要模态表现为与热带太平洋ENSO相联系的海盆尺度的一致性增暖或变冷特征，次级模态为热带印度洋SST偶极子模态．通过3组试验结果的比较表明，动量通量和热量通量异常强迫对热带印度洋SST变率第一模态均有贡献，但热量通量异常强迫的影响比动量通量异常强迫的作用大．热带印度洋偶极子模态主要受动量(风应力)异常强迫影响，热量通量异常强迫主要起阻尼作用．     

糖蜜发酵培养高铁营养酵母

采用生长周期短，易于工业化生产的酵母为菌株，以糖蜜为主要培养基，通过现代发酵工程技术，在3m^3发酵罐上进行中间试验，在12m^3发酵罐上试生产高铁营养酵母．其发酵产品高铁营养酵母铁的含量为1061mg／kg，高铁营养酵母的产率为2．54％，蛋白质的含量(质量分数)为51.90％.     

一类二阶积微分方程的控制问题

考虑了二阶非线性积微分方程的最优控制问题,其中系统中的主算子没有紧性,通过对控制变量附加条件,最后我们证明了Lagrange问题(P)最优控制的存在性.     

Ocean primary productivity estimation of China Sea by remote sensing

Ocean primary productivity is a key parameter in the research of globalcarbon cycle, ocean biological resources, and in evaluation of the feature and quality of ocean biological environment. Traditional shipboard measurement which is costly and time-consuming is impossible to obtain the spatial and temporal information on primary productivity on a large scale in a short period of time. Satellite remote sensing is an effective strategy to acquire the ocean information in near real time. Here we propose a model special for China Sea based on the concept of primary productivity using in situ primary productivity and environmental data from 1984 to 1990, and discuss every modeling parameter which can be retrieved by remote sensing in detail. The reliability of this model is tested by in situ data, and the comparison of other primary productivity models is made. We also analyze the temporal and spatial distribution of China Sea primary productivity in 2000. From our analysis the satellite remote sensing data have been proved very useful for ocean primary productivity study.