The effect of decrease in salinity on the dynamics of abundance and the cell size of <Emphasis Type="Italic">Corethron Hystrix</Emphasis> (Bacillariophyta) in laboratory culture

Effect of salinity on abundance dynamics and cell size of microalga Corethron hystrix Hensen (Bacillariophyta) were studied. C. hystrix can normally grow within a rather narrow salinity range between 32 and 28‰. The viable cells of this microalga change their morphological characters at a salinity of 24‰. This salinity level probably marks the beginning of cell division restriction, because the general number of cells by the end of the experiment was lower than in the control. The decrease of salinity to 16‰ caused pronounced irreversible morphological changes: cell height increased, chloroplasts compressed, protoplasm became granular, cytoplasm retracted, and spines shortened.     

Relationship between shell weight and cadmium content in whole digestive gland of the Japanese scallop Patinopecten yessoensis (Jay)

Seasonal and age-specific variations of cadmium (Cd) concentration in the digestive gland were investigated in the Japanese scallop Patinopecten yessoensis from Peter the Great Bay, Sea of Japan, with different degrees of Cd pollution. The seasonal changes in Cd concentrations of the digestive gland were inversely proportional to the dry weight of the gland. Concentrations of Cd and total Cd content (mug Cd per organ) increased with age (age-specific) to the same extent in contaminated and uncontaminated areas. There was also a strong positive correlation between Cd content in the whole digestive gland and shell weight and it is proposed that this relationship can be used as a new criterion for comparative evaluation of Cd levels in scallops from different areas We hypothesize that Cd is uptaken into scallops in proportion to the amount of calcium that absorbed through ion channels, and in addition, Cd in the digestive gland is in immobile forms (e.g. metal-rich granules) that accumulate with age. Moderate environmental pollution has no effect on the relationship between Cd content and shell size and the observed decrease in growth performance of the scallops from polluted areas may be due to other factors.     

Food and feeding habits of juvenile flounder Platichthys flesus (L.), abd turbot Scophthalmus maximus L. in the åland archipelago, northern Baltic Sea

The food choice of juvenile flounder (Platichthys flesus) and turbot (Scophthalmus maximus) was studied in the northern Baltic Sea during the years 1988, 1989, 1994 and 1995. The diet included organisms from 30 species/taxa in flounder (n = 306) and 10 species/taxa in turbot (n = 41). Flounder 45 mm mainly consumed meiofauna (dominating taxon: Harpacticoida, Copepoda) and larger fish (46–101 mm) consumed macrofauna (dominating taxa: Oligochaeta, Amphipoda and Chironomidae). In terms of biomass, macrofauna dominated for all sizes of flounders, and meiofauna was important only for the smallest fish. A strong seasonal variation could be detected in the diet. In spring, macrofauna dominated for all size classes of fish (only fish > 30 mm were caught in spring), while in summer and autumn meiofauna dominated the diets for fish 45 mm in size. Juvenile turbot (22–88 mm) consumed macrofauna and small fish. Turbot 30 mm consumed mainly amphipods, while > 30 mm turbot consumed mysid shrimps, amphipods and fish.The ontogenetic shift from meio- to macrofauna-sized prey in flounders occurs at a larger fish size in the northern Baltic Sea than reported in other areas, possibly depending on the increased relative importance of meiofauna in the northern Baltic. The seasonal variation in the diet could be due to seasonally changing abundances in the zoobenthos, or for the small fish (1-group, spring), to switching from meio- to macrofauna in order to optimize their energy gain. The 0-group flounders consumed meiofauna for a long period, possibly due to a learning-process or simply due to easy availability of meiofauna. Turbot has a much larger mouth gap than flounders, thus allowing them to consume macrofauna from the beginning of their benthic life.     

地图编制中的字形曲线变换

在信息完整的情况下,用在图形系统中作为标准图元形态的三次Bezier曲线来表达空间数据对数据加工、处理及传输具有重要意义。在地图文字的字库中,普遍的做法是用直线和二次Bezier曲线的集合来描述字符的字形轮廓,而二次Bezier曲线是非标准的曲线,在处理过程中带来很多不便。针对这一问题,本文研究用三次Bezier曲线拟合二次Bezier曲线的工作,提出了用三次Bezier曲线拟合二次Bezier曲线的方法并推证其计算公式。通过从字库中取出不同字体的字的轮廓曲线段进行实验,证明该方法实现了文字曲线图形的数据处理,对字库文字到地图文字的变换提供了有效的途径。     

晚第四纪构造与气候控制下的金沙江支流巴楚河阶地序列

河流阶地的形成过程研究是理解地区气候变化、构造隆升过程的重要手段。巴楚河地处青藏高原东南缘, 隶属于金沙江支流水系, 两岸阶地发育。因其独特的地理位置, 为第四纪以来青藏高原的隆升研究提供了天然场地条件, 对该地区金沙江水系的形成演化过程的研究也具有重要补充作用。野外勘查发现, 巴楚河发育有四级阶地。对阶地堆积物进行宇宙成因核素测年和光释光测年, 得到T1~T4阶地形成时代分别为1.7±0.1 ka、2.3±0.21 ka、4.5±0.5 ka和62.3±2 ka。T4阶地的形成主要为构造活动因素影响, T1~T3阶地的形成和阶地沉积物的堆积主要与气候有关。通过对阶地的拔河高度和形成时代的分析得巴楚河阶地下切速率由慢到快再平稳。研究结果对巴塘地区气候变化及构造运动历史的研究提供重要依据, 促进了该地区金沙江水系形成演化的研究, 与前人对青藏高原全新世以来隆升过程的研究相互呼应。

     

A white dwarf in the state of an ejector

We analyze the possibility of observational identification of white dwarfs in the state of an ejector. Among the distinctive features of this class of objects are a high rate of rotational energy loss comparable to or higher than the observed luminosity of the object and nonthermal gamma-ray and/or radio spectra. The manifestations of the white dwarf in the close binary system AE Aquarii closely match these criteria. We show that most of the peculiar manifestations of this object in the hard spectral range and the observed pattern of mass transfer in the system can be explained in terms of a model in which the state of the white dwarf is classified as an ejector.     

Influence of atmospheric circulation on precipitation in Altai Mountains

We analyzed the changes in precipitation regime in the Altai Mountains for 1959-2014 and estimate the influence of atmospheric circulations on these changes. Our study showed that during last 56 years the changes in the precipitation regime had a positive trend for the warm seasons(April-October),but weakly positive or negative trends for the cold seasons(November-March). It was found that these changes correspond to the decreasing contribution of “Northern meridional and Stationary anticyclone(Nm-Sa)” and “Northern meridional and East zonal(Nm-Ez)” circulation groups and to the increasing contribution of “West zonal and Southern meridional(Wz-Sm)” circulation groups,accordingly to the Dzerdzeevskii classification. In addition,it was found that the variation of precipitation has a step change point in 1980. For the warm seasons,the precipitation change at this point is associated with the reduced influence of “West zonal(Wz)”,“Northern meridional and Stationary anticyclone(Nm-Sa)” and “Northern meridional and Southern meridional(Nm-Sm)” circulation groups. For the cold seasons,a substantialincrease of “Wz-Sm” and a decrease of “Nm-Sa”,“Nm-Ez” circulation groups are responsible for the precipitation change in the two time periods(1959-1980 and 1981-2014).