Ecological factors related to the distribution of Bankia gouldi Bartsch in Chesapeake Bay

Organisms were collected on test panels, six inch lengths of dressed two by four inch pine, suspended in the water in a vertical position as described by Turner (1947). The panels were usually located at some convenient structure such as a dock-piling or sea-wall. Except where otherwise indicated by the data, the samples were collected from each station once a month between May 1950 and May 1953. During the three year period, seven hundred and nineteen panels were submerged in Chesapeake Bay. Approximately 14,000 organisms were encountered on these panels of which 20% or approximately 3,000 organisms could be identified from the dried pallets. Preliminary notes on the extent of fouling were made in the field after which the samples were removed to the laboratory for further study.

Fresh-water dinoflagellates of Maryland

Collections were made in the summer of 1942 and again at different times in 1946 and 1947. Some collections were not sufficient in numbers to allow for proper identification, so the present paper does not give a complete list. Of the 20 identified species reported on in the paper, two are new to science and ten have not been reported previously for the United States.

广布小蝶兰及两种根茎兰属植物的传粉生物学研究

植物与传粉者的关系并非一门独立的学科，它包含很多进化生物学的内容。传粉生物学研究为我们理解植物进化的一些关键问题，如生殖隔离、物种形成、适应进化等提供重要证据。兰科植物由于其精巧的花部结构及其独特的传粉机制，备受传粉生物学家的关注。从达尔文时代以来，有大量的文献记载了欧洲兰族植物的传粉生物学的各个方面，其中，共涉及4种欺骗性传粉方式，它们几乎代表了兰科植物中近1/3没有报偿兰花所有的欺骗类型。然而，到目前为止，尽管在中国有丰富的兰族植物资源，中国兰科植物的传粉生物学研究仍然很缺乏。 在本研究中，作者以黄龙自然保护区内兰族的2种根茎兰属植物和1种小蝶兰属植物为材料，研究它们的传粉生物学，并探讨他们之间的生殖隔离机制。 1． 根茎兰属Galearis 及小蝶兰属Ponerorchis植物的交配系统 所研究的2种根茎兰属植物和1种小蝶兰属植物人工自交授粉均可以成功结实。在自然条件下，广布小蝶兰和二叶根茎兰都必须依赖于昆虫才能结实成功，而黄龙根茎兰则是以自花授粉为主。 2． 广布小蝶兰Ponerorchis chusua的传粉系统 在黄龙自然保护区进行了连续2 年的野外观测和实验，结果表明，广布小蝶兰是一种自交亲和，但需要昆虫传粉的欺骗性植物。广布小蝶兰的主要传粉者为雌性Bombus rufofasciatus，雌性B. consobrinus wittenburg，B. cucorun的蜂王和雄性B. pyrosona。熊蜂对广布小蝶兰具有典型的欺骗性兰花传粉的特征，即访问十分迅速，并且一般一个植株只访问一朵花，避免了同株异花授粉。 3． 二叶根茎兰Galearis diantha的传粉系统 野外观察表明，二叶根茎兰只有一种有效的传粉者，其访问频率不高，访 问时间短，并且会一次访问一个植株的两朵花，不可避免的产生同株异花授粉。自然结实率为23.0－26.8％，人工授粉实验证明传粉者限制是结实率较低的主要原因。 4. 黄龙根茎兰Galearis huanglongensis的传粉系统 研究结果表明，黄龙根茎兰为自动自花授粉的植物，黄龙根茎兰的花粉约在花开放4天后，花粉块从花粉囊中掉出，由于重力作用，花粉块柄弯曲使花粉接触到柱头，完成传粉。 5. 根茎兰属Galearis及小蝶兰属Ponerorchis植物的生殖隔离机制 本文的研究表明，根茎兰属内的杂交及与小蝶兰属间植物之间人工杂交授粉均可以成功结实，它们物种之间的生殖隔离主要是通过受精前隔离机制。具有相同传粉者（B. rufofasciatus）的广布小蝶兰与二叶根茎兰通过机械隔离机制保持物种界限。

Water quality studies of the Delaware River with reference to shad migration

For some time pollution of the waters of the Delaware River by municipal and industrial wastes has been suspected of playing a major role in the decline of the shad fishery. Accordingly, studies were planned to ascertain whether any conditions of water quality caused by stream pollution and harmful or lethal to shad were existant in the waters of the Delaware River during the migration periods of the shad.

Toxicity of phenyl-mercuric lactate for fish

Phenyl-mercuric lactate is included in the pulp processing reagents by some paper mills to eliminate slime formation in the pulp. Small quantities of this chemical are added to the wet pulp in the beaters, particularly for the bactericidal action against Aerobacter aerogenes. Subsequently the mecurial is carried away in the wash waters. However, as the highly poisonous nature of many compounds of mercury is well known, questions have been raised concerning the pollution hazards created by phenyl-mercuric lactate in streams receiving effluents from mills using this substance.

ANNEALING BEHAVIOUR OF HIGH DOSE As** plus IMPLANTS.

The annealing behaviour of doses up to 4. 10**1**6 ions/cm**2 implanted at ion currents up to 10ma is described. Differences between rapid isothermal and furnace annealing in the measured sheet resistances are due to different amounts of diffusion and to loss of dopant by evaporation. Implantation at high currents (10ma) does not appear to affect the quality of the regrown material provided the temperature rise during implantation is small.

TECHNIQUES FOR PRODUCING DEFECT-FREE SOI BY DUAL ELECTRON BEAM HEATING OF DEPOSITED POLYSILICON.

Advances in the dual electron-beam recrystallization technique arising from the fast scanning of a line beam parallel to the edges of narrow seeding windows are described. The resultant recrystallized layers are essentially defect-free, have good surface flatness, and cover large areas.

The hammerhead sharks in Ceylon seas (Family Sphyrnidae)

The present study confirmed the previous listing of this species in the tropical seas around Ceylon (Misra 1947, Munro 1955). Photographs of the ventral surface of the head are shown in Fig. 1 and the distinguishing characteristics of the head are noted in the key to the species.

The wave transmission coefficients and coupling loss factors of point connected structures

This analysis is concerned with the calculation of the elastic wave transmission coefficients and coupling loss factors between an arbitrary number of structural components that are coupled at a point. A general approach to the problem is presented and it is demonstrated that the resulting coupling loss factors satisfy reciprocity. A key aspect of the method is the consideration of cylindrical waves in two-dimensional components, and this builds upon recent results regarding the energetics of diffuse wavefields when expressed in cylindrical coordinates. Specific details of the method are given for beam and thin plate components, and a number of examples are presented. © 2002 Acoustical Society of America.

Y染色体单倍型在中国汉族人群中的多态性分布与中国人群的起源及迁移

观察了由19个单核苷酸多态位点（SNP）组成的Y染色体单倍型在全国22个省市汉族人群中的分布。结果表明，中国南北人群的Y染色体单倍型组成有较大差异，南方人群的多态性明显高于北方人群，而后者中的单倍型仅含前者的一部分，其中单倍型H7，H10和H12仅出现在南方群体，这一观察结果与中国南北少数民族人群间差异相符，提示现代人类自南方进入中国，随后由南向北逐渐迁移，同时对携带南北人群共同的单倍型个体在3个Y染色体微卫星标记位点进行了基因组分型，据此估算了现代人类进入中国的时间大致在18000#approx#60000a前。

The status and significance of invertebrate communities

Invertebrates constitute a major link in energy flow culminating into fish production in aquatic ecosystems. In tropical water bodies relatively little research has been done on invertebrate ecology especially their role in fishery production. European scientists through periodic expeditions to Africa in the last quarter of the 20th century carried out the earliest research on zooplankton. Rzoska (1957) listed these early workers including Stuhlmann (1888), Weltner (1897) and Mrazek (1897-1898). Daday (1907), Verestchagin (1915) and Delachaux (1917) undertook further work during the early twentieth century. These earlyworks provide a useful basis for tracking community changes by comparison with modem investigations. Worthington (1931) provided the first quantitative account of the zooplankton of Lake Victoria along with information on diurnal vertical migrations, compared to a temperate lake. The establishment of the East African Freshwater Fisheries Research Organisation (EAFFRO) at Jinja in 1947 enabled investigations on the fisheries, algae, invertebrates and water quality aspects of the lake (EAFFRO Annual Reports 1947-1977) to be regularly carried out. Macdonald (1956) made the first detailed observations on the biology of chaoborids and chironomids (IakefJies) in relation to the feeding of the elephant snout fish, Mormyrus kannume. A detailed study of the biology of the mayfly, Povilla adusta Navas with special reference to the diurnal rhythms of activity was carried out by Hartland-Rowe (1957). The search to unravel the ecological role of aquatic invertebrates in the production dynamics of the lake has taken invertebrate research to greater heights through recent investigations including Okedi (1990), Mavut

Effect of superstructure stiffness on liquefaction-induced failure Mechanisms

Soil liquefaction following strong earthquakes causes extensive damage to civil engineering structures. Foundations of buildings, bridges etc can suffer excessive rotation/settlement due to liquefaction. Many of the recent earthquakes bear testimony for such damage. In this article a hypothesis that "Superstructure stiffness can determine the type of liquefaction-induced failure mechanism suffered by the foundations" is proposed. As a rider to this hypothesis, it will be argued that liquefaction will cause failure of a foundation system in a mode of failure that offers least resistance. Evidence will be offered in terms of field observations during the 921 Ji-Ji earthquake in 1999 in Taiwan and Bhuj earthquake of 2001 in India. Dynamic centrifuge test data and finite element analyses results are presented to illustrate the traditional failure mechanisms. Copyright © 2010, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited.

Drain groups in liquefiable soil

One of the major concerns for engineers in seismically active regions is the prevention of damage caused by earthquake-induced soil liquefaction. Vertical drains can aid dissipation of excess pore pressures both during and after earthquakes. Drain systems are designed using standard design charts based around the concept of a unit cell, assuming each drain is surrounded by more drains. It is unclear how predictable drain performance is outside that unit cell concept, for example, drains at the edge of a group. Centrifuge testing is a logical method of performing controlled experiments to establish the efficacy of vertical drains. Centrifuge testing is used to identify the effect of drains dealing with very different catchment areas. The importance of this is further highlighted by the results of a test where the same drains have been modified so that each should behave as a unit cell. It is shown that drains with large catchment areas perform more poorly than unit cells, and also have a knock-on detrimental effect on other drains. Copyright © 2011, IGI Global.