Diet of giant kokopu,Galaxias argenteus

The stomach contents of 105 preserved specimens of giant kokopu, Galaxias argenteus (Gmelin 1789), collected from various locations around New Zealand between c. 1963 and 1994, were used to investigate giant kokopu diet. A total of 76 food taxa, predominantly invertebrates, were identified and categorised as either of aquatic or terrestrial origin from the 91 stomachs that contained food items. Aquatic Trichoptera, Gastropoda, and Hemiptera comprised 29.1, 12.6, and 14.4% by abundance respectively, and terrestrial Coleoptera 12.2% by abundance. Adult terrestrial Coleoptera were the most commonly occurring taxa, and were found in 59% of the stomachs that contained food. Food items of aquatic origin occurred in 94.5% of the giant kokopu stomachs that contained food and comprised 74.9% of the items by abundance. Although fewer items of terrestrial origin were encountered, they nevertheless appeared to be a significant component of the diet, and occurred in 83.5% of the giant kokopu stomachs that contained food, and comprised 25.1% of the items by abundance. Items of terrestrial origin occurred slightly more frequently in giant kokopu from lotic habitats than from lentic habitats. The significance of terrestrial food may be associated with giant kokopu preference for habitats with riparian cover. Fish also appeared to be a significant component of the diet, as 26% of the giant kokopu examined contained fish remains. Giant kokopu are probably best described as generalist feeders, as they utilise a wide range of foods of both aquatic and terrestrial origin.     

松辽冰盖与松辽分水岭翘板迁移间的动力关系探讨

广布于松辽平原科尔沁沙地的巨型弧形沙垄的成因一直未能得到很好解释,该项研究采用罗根冰碛变形机理对该区的巨型弧形沙垄、密布的湖泡等特征地貌进行分析,发现其与斯堪的纳维亚冰盖、劳伦泰德冰盖的冰下软基变形地貌特征具有同一性,从而确认巨型弧形沙垄为冰盖冰流形成的巨型流线、罗根冰碛与锅穴构造的遗留,从而佐证了“松辽冰盖”的存在。研究发现松辽平原的巨型弧形流线显示出具有从盆地周围向沉降中心延伸、汇聚的特征,这表明流线的走向受制于地势的控制,而非所谓的风力所为。此外根据巨型冰川流线的展布形态与松辽分水岭之间存在的反常关系,发现在冰盖消融后松辽分水岭发生了北移现象,这一现象的产生可能与冰盖消融后导致的松辽盆地的失压反弹隆升有关。根据松辽分水岭的迁移时间、风沙层序年龄、荷载构造扰动地层年龄的综合约束,初步判断松辽冰盖的最近一次的发生时间在晚更新世早期(MIS4阶段)的东山冰期。     

彗木相撞的不可压缩分层流体模型

提出了一个彗木相撞的线性模型．在这个模型中，将木星大气看作是一个分层的、不可压缩和无粘滞的流体层，而与撞击相联的引力波则由一个初始冲力所造成．采用初始冲压P(r，z，0)代替初始表面形变作为初始条件．发现这种做法使得问题的数学处理更加方便，特别是在计算流体粒子的垂直位移和摄动势能方面，后者可以表为P(r，z，0)的有限傅立叶正弦和余弦变换．导出了一个联系彗星碰撞参数、木星大气参数和所设初始冲力之间的关系式．还对两种P(r，z，0)的假设形式分析地导出表面波波高．     

Structure and Dynamics of the Centaur Population: Constraints on the Origin of Short-Period Comets

The origin of Jupiter-family comets is linked to the intermediate stage of evolution through the Centaur region. Thus the structure of the Centaur population provides important constraints on sources of short-period comets. We show that our model of the Oort cloud evolution gives results which are consistent with the orbital distribution of observed Centaurs. In particular, it explains the existence of the large population of Centaurs with semimajor axes greater than 60 AU. The main source for these objects is the inner Oort cloud. Both Jupiter-family and Halley-type comets are produced by Centaurs originating from the Oort cloud. The injection rate for Jupiter-family comets coming from the inner Oort cloud is, at least, not less than that for a model based on the observed sample of high-eccentricity trans-Neptunian objects.     

夹金山脉大熊猫栖息地自然遗产的国家公园管理模式

大熊猫栖息地是全球关注的生态系统和价值最突出的自然遗产之一。夹金山脉既是重要的大熊猫栖息地,又是独特的风景区域,“四川大熊猫栖息地———卧龙.四姑娘山.夹金山脉”世界自然遗产已获得了联合国教科文组织第30届世界遗产委员会的提名。目前的以省级为主的多个风景名胜区与自然保护区分别管理,已不能满足保护其突出的遗产价值的要求。作者提出从国家层面上,规划夹金山脉大熊猫栖息地国家公园统一整体管理该项遗产,以增强有效管理能力。然后讨论了夹金山脉在生物多样性保护上的重要性与风景资源价值,论证了国家公园的管理模式,并从国际上关于国家公园的界定、中国国家公园的法律依据、国家公园管理世界自然遗产,分析了国家公园管理大熊猫栖息地自然遗产的可行性。     

超大型钨多金属矿床成矿特殊性──以湖南柿竹园矿床为例

 柿竹园超大型钨多金属矿床形成具有一系列特殊因素:三期高度分异花岗质岩浆的先后叠加,并同为高热花岗岩,前两期又为BELIF花岗岩。与三期花岗岩有关,形成了三大成矿系统。这三大成矿系统内的多级次接触交代一退化蚀变、多层次裂隙控矿及泥质大理岩的屏蔽作用,导致成矿物质的最大富集和有效保存,以致于形成巨大的含矿矽卡岩体,退化蚀变岩和云英岩。NE和EW向两组深大断裂交织致使热流上涌及花岗质岩浆的多期定位,使柿竹园地区在70多百万年时期保持着高温度环境,这不仅有益于各期岩浆的分异演化和期后成矿,还利于形成热水对流系统,将原分散在地层岩石中的成矿元素活化、运移和沉淀。另外,地球物质分布不均一性及华南地区地质成矿发展历史揭示出燕山期在湘南地区必然形成超大型钨多金属矿床。     

The lost city of north‐west Queensland: a test of the model of giant Grikeland development in semi‐arid Karst

Jennings and Sweeting's (1963) model of landscape evolution in the Limestone Ranges of Western Australia has been proposed as a general scheme of semi‐arid karstification by Williams (1978) and Ford and Williams (1989). The model involves an initial plateau surface which undergoes progressive karstic dissection. The resultant landscape is characterised first by giant grikelands, then by box valleys and finally by karst towers. The depth of dissection is governed by the altitude of successive levels of pediplanation adjacent to the karst, with each karst level representing the location of a former erosion surface. The Lost City, a giant grikeland in the Barkly karst of north‐west Queensland, has evolved by the karstic dissection and stripping of a gently dipping sequence of carbonates and cherts. By contrast with the type example, the depth of dissection, the altitude of successive surfaces, the form and even the location of the grikeland are all controlled by rock structure. Not only does this cast doubt on the general applicability of Jennings and Sweeting's model, it suggests that such landscapes may also be the result of structural control and that the role played by semi‐arid climates may be less important than has previously been proposed. Given our present poverty of knowledge of semi‐arid karstification, any attempt to identify type examples of semi‐arid karst may be premature.     

DISTRIBUTION FEATURES OF GIANT SEA-SALT NUCLEI IN ATMOSPHERE OVER YONGXING ISLAND, XISHA ISLANDS,DURING NORTHEAST WINTER MONSOON

In this paper, the chlorine ions nuclei data, observed at Yongxing (Xisha Islands) during November 1987, are analyzed. The main results are:1) The average concentration of chiorine ions nuclei with dry diameters larger than 2 μm is 878 per litre and the average salt content is 105. 4μg/m³, in which special giant nuclei with dry diameters larger than 4 μm are 19O per litre. The largest dry diameter of chloride ions observed reaches 57 μm, which are larger than that observed there during the southwest summer monsoon. The spetrum type shows quasi-unimodal and exponential lapse. 2) The salt content decreases with the height over sea surface. 3) The concentrations of chlorine ions nuclei reach the maximum value at 0800 (Local time, same below). and minimum at 0200.     

Energy and Stress Distributions in Ellipsoids

A closed form solution for a uniform, isotropic, homogenous, rotating, and self-gravitating solid ellipsoid is analyzed as a function of its material properties and angular momentum. This solution recovers the classical results for an incompressible material, namely that Maclaurin and Jacobi ellipsoids minimize the total strain energy of an ellipsoid. As the solid becomes compressible we find that Maclaurin-type spheroids are energetically preferred over all relevant values of angular momentum, although the gradient toward these spheroids is weak, at best. Compressibility allows the weak minima to encompass most observed asteroid shapes.Using this solution, a simple failure criterion of maximum principal stress is examined. Under this failure criterion, an ellipsoid rotating at a sufficiently rapid rate can have positive stress on the periphery and in the polar regions. Contours for this failure theory are compared with estimated asteroid rotation rates and ellipsoidal shape estimates. For compressible materials there is surprisingly good correspondence for such a simple theory and criterion, with the failure curve delimiting a demarcation that few observed asteroids cross.This research has implications for the shapes and distortions of rubble pile asteroids. In particular, the theory gives insight into the internal stress field and the effects of energy dissipation in an asteroid after it has been boosted into a nonminimum energy configuration due to an impact event or a close flyby with a planet. Internally there are double-lobed compressive stress regions reminiscent of the external shape of Kleopatra.     

Evolution of Comet Nucleus Rotation

The secular evolution of comet nucleus rotation states subject to outgassing torques is studied. The dynamical model assumes that the nucleus inertia ellipsoid is axially symmetric. The outgassing torques acting on the surface are modeled using standard cometary activity formulae. The general rotational equations of motion are derived and separately averaged over the fast rotational dynamics terms and the comet orbit. Special cases where the averaging assumptions cannot be applied are evaluated separately. The modification of the comet orbit due to comet outgassing is neglected. Resulting from this analysis is a system of secular differential equations that describes the dynamics of the comet nucleus angular momentum and rotation state. We find that the qualitative secular evolution of the rotation state is controlled by a single parameter that combines parameters related to the comet orbit and parameters related to the nucleus surface geometry and activity. From this solution, we find qualitatively different evolutionary paths for comet nuclei whose entire surface is active, as compared to nuclei with only a single active region. For surface activity models between these extremes, we show that certain evolutionary paths are more likely than others. Additionally, our solution indicates that a comet nucleus' rotational angular momentum will tend to increase over time, potentially contributing to the observed phenomenon of comet nucleus splitting.