一维铁磁链中量子孤波的能级和磁矩

使用Hartree近似和一种简化的准离散多标度方法,研究了具有交换作用和经典磁矩相互作用的一维铁磁链中的量子孤波解. 这种一维铁磁链中不仅存在着运动的量子孤波,也存在着静态的量子孤波(即量子内禀局域模).利用所获得的量子孤波解,进一步研究了量子孤波的能级和由量子孤波所携带的磁矩. 研究表明,量子孤波的能量和磁矩都是量子化的,这些结果为正确理解磁性材料中像磁滞回线的量子台阶等宏观量子特性提供了一条可能的途径.     

斑节对虾虾苗白斑综合症杆状病毒的检测和养殖跟踪

利用 2步 PCR检测技术对湛江和阳西地区的虾苗进行白斑综合病杆状病毒 ( WSSV)检测。在仔虾 2日龄最早检测到病毒 ,有 2 5%的虾苗带有 WSSV病毒。带病毒虾苗和不带病毒虾苗分别在不同养殖模式的养殖过程中跟踪。前者在湛江湖光镇普通虾塘跟踪养殖 ,它们在变化的环境中容易发病 ,p H、盐度和温度是重要的诱发因子 ,在养殖 50～ 60 d时发病死亡 ;后者在高位池和普通池养殖跟踪 ,它们对变化的环境有较大的适应性 ,养殖时间为 80～ 1 1 0 d,在相对优良的养殖技术条件下大部分可望养殖成功。环境中有 WSSV病原传入 ,不带病毒虾苗在养殖后期可以带有 WSSV病毒 ,出现白斑虾。跟踪的普通池有爆发病害 ,但是时间延后 ,跟踪的高位池没有爆发病害。     

兰州市城市供水现状评价及可持续发展对策研究

兰州市辖3县5区,总面积1.3万km2。位于陇西黄土高原西部,海拔1 500~3 500m,地势总体上表现为西南部高、东北部低。广覆黄土的低山丘陵及其夹峙的河谷平原,构成了本区的基本地貌景观。平原区生态地质环境较好,特别是河谷平原内的一、二级阶地,具有地形平坦、地势开阔的优越条件,是人类生产与生活最佳地段、也是人口相对密集的区域,如兰州黄河河谷平原、永登庄浪河谷平原、榆中盆地、秦王川盆地等。本文剖析,评价其供水现状,提供可持续发展的对策,具有重要意义。     

台风诱发暴潮极端潮位的预测方法

以杭州湾为例,根据水文站历史潮位资料,采用改进的灰色马尔可夫预测模型对台风诱发暴潮的极端潮位进行预测.同时采用复合极值分布理论对可能出现的极端潮位进行概率预测,使预测结果更为接近真实数值.     

Sediment supply to the Orange sedimentary system over the last 150 My: An evaluation from sedimentation/denudation balance

The South African plateau is bordered by passive margin basins preserving the terrigeneous sediment produced during onshore erosion. As such, these basins potentially provide a record of the variation in onshore elevation and relief over time. Here we bring new constraints on the uplift and erosion of the Southern African plateau over the last 150 Ma from the perspective of the stratigraphic architecture of these basins. We review published data to quantify the terrigeneous supply eroded in the drainage area and preserved in the basins. The novel aspect of our approach is the integration of the evolution of the whole domain in sedimentation (i.e. not only the platform) as well as the onshore eroding region.     

Markov chain Monte Carlo (MCMC) sampling methods to determine optimal models,model resolution and model choice for Earth Science problems

We present an overview of Markov chain Monte Carlo, a sampling method for model inference and uncertainty quantification. We focus on the Bayesian approach to MCMC, which allows us to estimate the posterior distribution of model parameters, without needing to know the normalising constant in Bayes' theorem. Given an estimate of the posterior, we can then determine representative models (such as the expected model, and the maximum posterior probability model), the probability distributions for individual parameters, and the uncertainty about the predictions from these models. We also consider variable dimensional problems in which the number of model parameters is unknown and needs to be inferred. Such problems can be addressed with reversible jump (RJ) MCMC. This leads us to model choice, where we may want to discriminate between models or theories of differing complexity. For problems where the models are hierarchical (e.g. similar structure but with a different number of parameters), the Bayesian approach naturally selects the simpler models. More complex problems require an estimate of the normalising constant in Bayes' theorem (also known as the evidence) and this is difficult to do reliably for high dimensional problems. We illustrate the applications of RJMCMC with 3 examples from our earlier working involving modelling distributions of geochronological age data, inference of sea-level and sediment supply histories from 2D stratigraphic cross-sections, and identification of spatially discontinuous thermal histories from a suite of apatite fission track samples distributed in 3D.     

Different crab species influence feeding of the snail Nucella lapillus through trait‐mediated indirect interactions

Indirect interactions are among the many important factors that influence the community structure of the rocky intertidal zone. Trait‐mediated indirect interactions, in which the presence of a predator or competitor can influence the relationship between two other species, have emerged as vital for understanding community dynamics. This study examined the effect of different crab species on the feeding habits of an intertidal snail, Nucella lapillus. Crab species were defined as being sympatric predatory (Carcinus maenas and Cancer irroratus), sympatric non‐predatory (Uca pugnax and Pagurus longicarpus), or allopatric predatory (Mithrax sculptus and Percnon gibbesi). Nucella lapillus were potentially exposed to risk cues from each of the crab species. Crabs were kept in perforated boxes, which allowed any chemical cues to be emitted but prevented direct contact. Nucella lapillus had significantly lower feeding rates in the presence of sympatric predatory crab species than N. lapillus exposed to either sympatric non‐predatory crabs or allopatric predatory crabs. There was no difference in feeding rate between N. lapillus exposed to the sympatric non‐predatory crabs and to the allopatric predatory crabs. Nucella lapillus in the presence of sympatric predatory crabs had a feeding rate of only 0.07 barnacles per snail per day, whereas N. lapillus housed with non‐predatory crabs and allopatric predatory crabs had rates of 0.11 and 0.12, respectively, suggesting that N. lapillus alter their behavior in response to chemical risk cues from local predators. These results suggest that the ability to detect and respond to risk cues is a selectively evolved trait.     

Role of mysid seasonal migrations in the organic matter transfer in the Curonian Lagoon,south-eastern Baltic Sea

We investigated population dynamics, growth and feeding of an omnivorous mysid, Paramysis lacustris, performing seasonal horizontal migrations in the Curonian Lagoon. In autumn, increased predation pressure and deteriorated feeding conditions, due to zooplankton and phytoplankton decline in the open water, forces mysids to migrate to the shoreline, where large amounts of decaying submersed vegetation occur at the end of plant growth season. Using stable isotope analysis and mixing models, we evaluated relative importance of decaying submersed macrophytes, lagoon phytoplankton and mesozooplankton in the diet of mysids during this period. In September–November, mysids actively grew and produced three cohorts. Specific growth rates of adults (10.9 ± 1.9 mm) and subadults (6 ± 0.5 mm) were 3 and 9% DW d⁻¹, respectively, resulting in population somatic production of 36 g DW m⁻². Both δ¹⁵N and δ¹³C of mysids varied in concert with those in suspended and bottom particulate organic matter (POM) and mesozooplankton. The mixing models estimated that 45% of mysid diets were composed of bottom POM originated from the decaying macrophyte Potamogeton perfoliatus, 45% by suspended POM largely consisting of phytoplankton, while mesozooplankton contributed less than 10% of the diet. This diet composition differs from that in summer, when mysids rely mostly on zooplankton and phytoplankton. Therefore, mysid horizontal migrations and their ability to efficiently utilize littoral detritus improve the efficiency of macrophyte detritus transfer up the food chain and inshore/offshore habitat coupling in the Curonian Lagoon.     

Geographical and seasonal variations in biomass and estimated production rates of net zooplankton in Yatsushiro Bay, Japan

The biomass and production rate of net zooplankton were studied at eight stations in Yatsushiro Bay, Japan, monthly from May 2002 to April 2003. Based on environmental conditions, the bay was divided into three regions, viz. northern (average depth, salinity and chlorophyll a concentration: 11 m, 31.8 and 6.5 μg l⁻¹, respectively), central (30 m, 32.8 and 3.2 μg l⁻¹, respectively) and southern (43 m, 33.4 and 1.9 μg l⁻¹, respectively). Net zooplankton biomass was high in warm months and low in cold ones, with annual averages of 20.2, 38.8 and 16.4 mg C m⁻³ in the northern, central and southern regions, respectively. Copepods were the most important constituent (>ca. 70% of net zooplankton biomass) in all regions. The northern region was characterized by the dominance of Oithona spp. in summer and Acartia spp. in winter-spring. In the central region, Microsetella norvegica was most pronounced in summer-fall. In both central and southern regions, Calanus sinicus and Eucalanus spp. dominated in winter-spring and fall, respectively. The annual average net zooplankton secondary production rate was 4.4, 7.5 and 3.9 mg C m⁻³d⁻¹ in the northern, central and southern region, respectively. Combining the results from the present study with those from other collaborative works on microzooplankton allowed us to determine the trophic interactions in Yatsushiro Bay. If the secondary producers depend entirely on phytoplankton for food, their daily carbon requirement is equivalent to 12.5, 21.6 and 19.1% of the phytoplankton biomass in the respective regions.     

网箱养殖石斑鱼病毒性神经坏死病流行调查

厦门海水网箱养殖石斑鱼春、夏季节暴发性疾病经过流行病学调查和病原检测,确认主要病原为病毒性神经坏死病毒,病鱼外观表现典型的神经异常症状。应用逆转录聚合酶链式反应（RT—PCR）技术检测5种石斑鱼：赤点石斑鱼（Epinephelus akaara）、青石斑鱼（E．awoara）、云纹石斑鱼（Emoara）、紫石斑鱼（E．lanceolatus）、马拉巴石斑鱼（E．malabaricus）.检测76条石斑鱼,检出率90％;病鱼的脑、视网膜、肾脏、肝脏、脾脏等组织均能检出神经坏死病毒（NNV）,以脑和视网膜检出率最高,肾脏次之,肝脏、脾脏检出率较少,鳃未检出。