A late Pliocene diatom Ge/Si record from the Southeast Atlantic

As a result of both culture and sediment core studies, the ratio of germanium (Ge) to silicon (Si) in diatom shells has been proposed as a proxy for monitoring whole-ocean changes in seawater Ge/Si, a ratio affected by changes in continental weathering. However, because of the difficulties of extracting and cleaning diatom frustules from deep-sea sediments, only samples from highly pure diatom oozes in the Antarctic region have been previously analyzed. Here we present data on diatom Ge/Si ratios, (Ge/Si)_opal, for the time interval between 3.1 and 1.9 Ma from a mid-latitude, coastal upwelling area where significant terrigenous sediment input complicated the sample processing and analyses. In general, our (Ge/Si)_opal values show the same decreasing trend after 2.6 Ma than previously measured in Antarctic sediments (Shemesh et al., 1989. Paleoceanography 4, 221–231), but with a noisier background that may reflect the local imprint of proximal continental input superimposed upon global changes in the ocean reservoir. The time of initiation of large-scale North Hemisphere glaciation at 2.6 Ma is characterized by a declining pattern of diatom Ge/Si ratios, which could have resulted from a global increase in the input of riverine Si due to enhanced silica weathering and/or equatorward (northward) intrusions of subantarctic waters enriched in silica. High (Ge/Si)_opal ratios are associated with high opal contents from the same sediment samples and with warm climate as indicated by depleted benthic foraminiferal δ¹⁸O values from the North and Equatorial Atlantic. Cold periods signified by enriched benthic δ¹⁸O values, on the contrary, are associated with lower (Ge/Si)_opal ratios. We interpret diatom Ge/Si values to reflect the prevailing weathering state on the continents, with greater chemical weathering during warm and wet periods of the Pliocene and less during cooler and drier intervals.     

东海陆架前缘斜坡(冲绳海槽西坡)北部的断块隆脊地貌

东海陆架前缘斜坡(冲绳海槽西坡)北部的断块隆脊,是呈长条形的脊状台式隆起,位于29°30′N-31°10′N;128°00′E-128°20′E之间。其由NNE向链状排列的断块山地组成,且与NNE向的断裂构造相一致,其顶部水深约300m～400m左右。从实测单道地震剖面看,隆脊的东西两侧均有断层出现。隆脊西坡倾向陆架一侧,坡度大,有的地方坡度超过10°;而东侧坡度较缓,仅1°左右,缓倾至海槽西坡坡底,并以沟坎式与冲绳海槽槽底相连。冲绳海槽地区的构造运动,使隆脊地区受到断裂构造的作用。NNE向的大断裂使该隆脊位置的东西两侧断裂下降而中间抬起,加之下部岩浆上侵,显现出链式排列的断块山地,表现为一条长形的断块隆脊构造地貌体。推测该地貌体形成的时期较晚,它是与断层的发生同时期形成的。     

锯缘青蟹胚胎发育过程主要生化组成

锯缘青蟹胚胎３种主要生化组成以蛋白质含量为最高，脂类含量次之，碳水化合物含量最低。胚胎发育的结果导致三种主要生化组成含量降低，其中蛋白质减少了３９．０％，脂类、碳水化合物含量分别减少了１７．０％、７．７％，说明蛋白是青蟹胚胎发育的主要能源物质，这可能与动物适应热带、亚热带的水生环境有关。     

海湾扇贝肝素样多糖分离方法的研究

于1992年1月-1993年2月，对从海湾扇贝中提取获得的糖胺聚糖（GAG）用乙醇和溴化十六烷基三甲铵（CTAB）分级分离，并对所得制品用琼脂糖凝胶电泳和高效液相色谱验证，以研究一种简便、快速的分离提纯方法。结果表明，扇贝GAG水溶液在乙醇量60％时分离获得的级分，其GAG－GTAB给合物再用2.0 mol/LNaCl溶液解离得到的主要级分，琼脂糖凝胶电泳和高效液相色谱均显示出单一区带，红外光谱类似干肝素的。证明这一提纯过程是一简便、快速的分离提纯方法。     

单锚腿系泊系统动力计算的新方法

在Hamilton型拟变分原理体系下,建立了一种时间子域以三次和五次B样条函数插值的时间子域法,并将这种新方法用于单锚腿系泊系统的动力响应分析中。算例表明,新方法比传统的动力计算方法Wilson-θ法,在计算精度上有明显的优势,表明本方法能够用于计算单锚腿系泊系统的动力响应。     

基于极限学习自编码器的水声信号目标识别方法

传统的机器学习方法在特征提取时容易受到主观经验的影响,导致对水声信号目标的识别准确率不高。而一般深度学习算法模型较复杂,通常具有训练耗时、计算复杂度高等缺点。极限学习自编码器具有很强的非线性处理能力,适合针对具有非线性特点的水声信号目标的识别,而且模型具有学习速度快,泛化能力强等显著优势。将极限学习自编码器算法应用于水声信号目标识别中,并与卷积神经网络、自编码器和极限学习机识别方法进行对比,结果表明：提出的方法对水声信号目标识别的准确率最优,且训练时间较短。     

The application of cutting plus waterlogging to control Spartina alterniflora on saltmarshes in the Yangtze Estuary,China

Control and eradication of the exotic and invasive plant Spartina alterniflora within the Chongming Dongtan nature reserve, Shanghai, China, is vital for the management and conservation of the saltmarshes. A demonstration project was established using waterlogging and cutting to control this invasive species. Results from 2007 to 2008 showed that, although the managed waterlogging significantly reduced biomass and seed production of S. alterniflora at an early stage, the species subsequently showed rapid adaptation to the long-term waterlogging stress. Thus, managed waterlogging alone was insufficient for the effective eradication of S. alterniflora. However, managed waterlogging for around 3 months, combined with cutting the above-ground part of S. alterniflora at a key stage (flowering period in July), controlled and eradicated the plant successfully. Both the above-ground and below-ground parts of S. alterniflora were killed and the plants began to decompose after 3 months. Furthermore, there was no re-growth of the emergent part of S. alterniflora in the following years. However, once the impounded water was released restoring the natural hydrodynamic regime of the saltmarshes, the seeds and seedlings of S. alterniflora reinvaded the controlled site from the neighboring areas and the S. alterniflora community was re-established. Thus, after eradication of S. alterniflora, control measures should be maintained to prevent the re-establishment of S. alterniflora. The results of this demonstration project indicate a potentially useful and effective approach for the control and management of large-scale invasion by S. alterniflora on saltmarshes in the Yangtze Estuary, China.     

Appraisal of storm beach buffer width for cyclonic waves

The loss of beach sand from berm and dune due to high waves and surge is a universal phenomenon associated with sporadic storm activities. To protect the development in a coastal hazard zone, hard structures or coastal setback have been established in many countries around the world. In this paper, the requirement of a storm beach buffer, being a lesser extent landward comparing with the coastal setback to ensure the safety of infrastructures, is numerically assessed using the SBEACH model for three categories of wave conditions in terms of storm return period, median sand grain size, berm width, and design water level. Two of the key outputs from the numerical calculations, berm retreat and bar formation offshore, are then analysed, as well as beach profile change. After having performed a series of numerical studies on selected large wave tank (LWT) test results with monochromatic waves using SBEACH, we may conclude that: (1) Berm erosion increases and submerged bar develops further offshore as the storm return period increases for beach with a specific sand grain size, or as the sand grain reduces on a beach under the action of identical wave condition; (2) Higher storm waves yield a large bar to form quicker and subsequently cause wave breaking on the bar crest, which can reduce the wave energy and limit the extent of the eroding berm; (3) A larger buffer width is required for a beach comprising small sand grain, in order to effectively absorb storm wave energy; and (4) Empirical relationships can be tentatively proposed to estimate the storm beach buffer width, from the input of wave conditions and sediment grain size. These results would benefit a beach nourishment project for shore protection or design of a recreational beach.     

Laboratory tests of vortex-induced vibrations of a long flexible riser pipe subjected to uniform flow

Laboratory tests have been conducted on vortex-induced vibration (VIV) of a long flexible riser towed horizontally in a wave basin. The riser model has an external diameter of 16 mm and a total length of 28.0 m giving an aspect ratio of about 1750. Reynolds numbers ranged from about 3000 to 10,000. Fiber optic grating strain gages are adopted to measure the dynamic response in both cross-flow and in-line directions. The cross-flow vibrations were observed to vibrate at modes up to 6 and the in-line reached up to 12. The fundamental response frequencies can be predicted by a Strouhal number of about 0.18. Multi-mode responses and the asymmetry of the bare pipe response in uniform flow were observed and analyzed. The experimental results confirmed that the riser pipe vibrated multi-modally despite it being subject to a uniform current profile and all of the excited modes vibrated at the Strouhal frequency. The asymmetrical distribution of displacement mainly resulted from the modal composition. Higher harmonics of the VIV response such as the third, fourth and fifth harmonics frequencies were found to be steady over the entire duration of the test even if they varied along the length of the riser pipe.     

Quantitative proteomics provides insight into the response of the marine dinoflagellate Prorocentrum donghaiense to changes in ambient phosphorus

Dinoflagellates are the major causative agents of harmful algal blooms in the global ocean and they usually form blooms under conditions of very low dissolved inorganic phosphorus(DIP). However, the mechanisms underpinning the dinoflagellate blooms remain unclear. Here, we quantitatively compared protein expression profiles of a marine dinoflagellate, Prorocentrum donghaiense, grown in inorganic P-replete, P-deficient, and DIP-and dissolved organic phosphorus(DOP)-resupplied conditions by employ...