Deep‐water ascidians from the North Atlantic (RV Academic Keldysh,cruise 46 and 49)

Ascidians from two locations in the North Atlantic are discussed. Predominantly small specimens of five known species were taken by Sigsbi trawl in the vicinity of the wreck of the Titanic (the region referred to as the Titanic location), and two large specimens of a Corynascidia species were taken by manned submersible MIR‐2 on the mid‐Atlantic Ridge (the Charlie Gibbs Fracture Zone). Definitions of the species are reviewed and their relationships and intraspecific variations are discussed and revised.     

A reassessment of neotropical species of Corvospongilla (Porifera: Spongillidae)

This paper expands the known geographic distribution of Corvospongilla seckti Bonetto and Ezcurra de Drago, 1966 to another two Brazilian hydrographic basins, the East Atlantic and São Francisco basins. Simultaneously, it reassesses the status of C. seckti and Corvospongilla volkmeri De Rosa Barbosa, 1988. Re-examination of the holotype of C. volkmeri revealed no remarkable diagnostic features to differentiate it from C. seckti, given our present knowledge on the variability of the latter. Accordingly, C. volkmeri is considered a junior synonym of C. seckti.     

Species of genus Schizotheca Hincks (Bryozoa,Cheilostomata) described in the Atlantic‐Mediterranean region,with notes on some species of Parasmittina Osburn

Material held in collections, originally ascribed to the genus Schizotheca and originating from the NE Atlantic and Mediterranean, is revised. Two new species are described: Schizotheca carmenae sp. nov. from Azores and Portugal, originally cited as Strophiella tubigera [sic], and Schizotheca buski sp. nov. from Cape Verde and Brazil, originally cited as Schizotheca fissa. Schizotheca talismani, also from Cape Verde, is redescribed from original material and transferred to the genus Parasmittina. The Atlantic species Schizotheca tuberigera is redescribed and a new synonymy is established. Schizotheca aviculifera, from Morocco, is also redescribed and a lectotype designated. A lectotype is also chosen for Schizotheca fissa, type species of the genus. Schizotheca lepida, from north France, is considered to be an unrecognizable species.     

Sipunculans and echiurans from the deep Angola Basin

Sipunculans and echiurans collected by the “DIVA 1” expedition by RV Meteor (Cruise M48/1) to the deep‐sea bottom of the Angola Basin are recorded. Seven species from five genera and two separate phyla are recognized; only the echiuran Pseudoikedella achaeta has not been recorded hitherto in the southern sector of the Atlantic Ocean. A gradient analysis using redundancy analysis (RDA) under the CANOCO package indicates the existence of a neat latitudinal gradient of sipunculans along the Angola Basin from the southernmost stations towards the northern ones. The local abundance of abandoned horny tubes of polychaetes at some of the sampling sites of the northernmost stations explains the dense aggregations of Nephasoma diaphanes. This species exhibits an opportunistic lifestyle inside empty polychaete tubes on the abyssal plains of the Angola Basin.     

An abyssal species of Sagitta (Chaetognatha) from the North East Atlantic

A Chaetognath species new to science, Sagitta abyssicola is described from specimens taken at abyssal depths (3500–4000 m) in the north east Atlantic Ocean and comparisons are made with related species of the ‘planctonis’ group namely S. planctonis Steinhaus, 1896, S. zetesios Fowler, 1905 and S. marri David, 1956. Ecological data are provided.     

New species of Corcyrogobius,Thorogobius and Wheelerigobius from West Africa (Teleostei: Gobiidae)

Three new West African species of gobiid fishes are described from the Gulf of Guinea in the tropical eastern Atlantic. These are Corcyrogobius lubbocki sp. nov., Thorogobius rofeni sp. nov. and Wheelerigobius wirtzi sp. nov. Generic features are discussed. T. rofeni, known from only the holotype, was trawled on the upper continental slope, an unusually deep occurrence for a gobiid species.     

基于本体的初中数学大纲知识表示方法研究

目前领域本体的构建,还缺乏系统有效的针对特定领域的工程化的方法。本文介绍了本体相关的基本理论,结合斯坦福大学的本体构建七步法实现了基于本体的初中数学大纲知识表示,分析和归纳了领域本体构建的一般步骤和方法,并对本体构建方法存在的问题提出了看法。     

实二次域K=Q(（5n）1/2)的整数环OK

用简单的证明方法推出实二次域K=Q(（5n）^1/2)（其中n为正整数,5n无平方因子）的整数环OK只有在n=24t+1（t∈Z）的时候才有可能是主理想整环,其他情况下,二次域K=(（5n）^1/2)的整数环OK一定不是主理想整环。     

A PRECONDITIONER FOR DOMAIN DECOMPOSITION METHODS WITH MORTAR LAGRANGE MULTIPLIERS

In this paper we consider the domain decomposition methods with mortar element Lagrange multipliers to two-dimensional elliptic problems. We shall construct a kind of simple preconditioners for the corresponding interface equation. It will be shown that condition number of the preconditioned interface matrix is almost optimal.