Immunotoxicity effect of benzo[α]pyrene on scallop Chlamys farreri

The toxic effects of benzo[α]pyrene (B[α]P) at different concentrations (0.1, 0.5, 1, 2.5 and 7.5 μgL⁻¹) on scallop (Chlamy farreri) immune system were studied. The results showed that B[α]P had significant toxic effects on the haemocyte counts, neutral red uptake, phagocytosis, bacteriolytic and antibacterial activity (P<0.05), while the seawater control and acetone control had no significant differences. The haemocyte counts, neutral red uptake, phagocytosis and bacteriolytic activity in all B[α]P treatment groups as well as antibacterial activity in groups of 0.5, 1, 2.5 and 7.5 μgL⁻¹ B[α]P decreased significantly (P<0.05). Some of these indices tended to be stable on the sixth day and others on the ninth day, and the indices showed clear time- and concentration-response to B[α]P. Bacteriolytic activity in 0.1μgL⁻¹ B[α]P treatment group and antibacterial activity in 0.1 μgL⁻¹ and 0.5 μgL- B[α]P treatment groups increased at the beginning of exposure and reached their peaks on day 1 and day 6, respectively. Following that, both activities decreased gradually and became stable after day 9. When all the indices reached stability, they were significantly lower than those in control group (P<0.05), except for antibacterial activity in 0.1 μgL⁻¹ B[α]P treatment group (P>0.05). Thus, B[α] has evident toxic effects on scallop immune system, which supports the view that a relationship exists between pollution and immunomodulation in aquatic organisms.     

Long-range forecasts of River Po discharges based on predictable solar activity and a fuzzy neural network model / Prévisions à long terme des débits du Fleuve Pô basées sur l’activité solaire prévisible et sur un modèle de réseau de neurones flou

Abstract

Abstract Is it possible to make seasonal and interannual forecasts of hydrological variables if one cannot predict next week’s rainfall? Contrary to common view, some scientists support the hypothesis that variations in mean global temperature and precipitation are controlled more by external forcing (solar variability and volcanic eruptions) than by increasing atmospheric concentration of greenhouse gases. Temperature and precipitation are connected with special phases of the 11-year sunspot cycle, which coincide with significant accumulation of energetic solar eruptions. Because of the possibility of identifying years with many solar eruptions, the attractive prospect emerges of the long-term hydrological forecasting based on cycles of solar activity. Starting from this assumption, an expert system was built based on a fuzzy neural network model for seasonal and interannual forecasting of the Po River discharge. It was found that indices of solar activity and of global circulation are sufficient to yield useful forecasts of hydrological variables.     

全新世以来南疆地区气候环境演变与人类活动的关系

根据南疆地区不同沉积相的沉积记录的研究 ,初步建立了南疆地区 1 2 ka BP以来气候环境演化序列。研究揭示 ,此期间南疆地区气候与环境的演变具有较为显著的西风型特征 ,共经历了 5次相对暖干和 4次相对冷湿时期。特别是在全新世大暖期中出现于 7.0～ 5.0 ka BP期间相对暖湿的气候环境特征可能与西南季风势力的增强有关 ,而且还揭示了此地区暖干化趋势存在阶梯式增强的特征 ,研究还发现 ,近 4ka BP以来 ,气候环境的变化与一些人文事件如古城的废弃、丝绸之路的兴衰和人地关系类型的演化存在着一定的关系。     

Comment la Terre a-t-elle pu vieillir de plus de quatre milliards d’années en quatre siècles ?

The history of the determination of the Earth's age is interesting in two ways. First, it is a great school for understanding the genesis of a scientific theory. It stands at the crossroads of almost all scientific disciplines, and also philosophy or even theology. This history shows how what one may well call a “scientific truth” was established through polemics. Second, that age of 4.567 billion years is not just another figure in the series of ages that would be of concern only to astrophysicists; this scale is the only one that makes it possible to understand the genesis of the marvelous order of the solar system (that Newton attributed to God) and the fantastic complexity of Life on Earth.     

Delay-dependent stability and added damping of SDOF real-time dynamic hybrid testing

It is well-recognized that a transfer system response delay that reduces the test stability inevitably exists in real-time dynamic hybrid testing (RTDHT).This paper focuses on the delay-dependent stability and added damping of SDOF systems in RTDHT.The exponential delay term is transferred into a rational fraction by the Padé approximation, and the delay-dependent stability conditions and instability mechanism of SDOF RTDHT systems are investigated by the root locus technique.First, the stability conditions are discussed separately for the cases of stiffness, mass, and damping experimental substructure.The use of root locus plots shows that the added damping effect and instability mechanism for mass are different from those for stiffness.For the stiffness experimental substructure case, the instability results from the inherent mode because of an obvious negative damping effect of the delay.For the mass case, the delay introduces an equivalent positive damping into the inherent mode, and instability occurs at an added high frequency mode.Then, the compound stability condition is investigated for a general case and the results show that the mass ratio may have both upper and lower limits to remain stable.Finally, a high-emulational virtual shaking table model is built to validate the stability conclusions.     

Solar radiation,longwave radiation and emergent wetland evapotranspiration estimates from satellite data in Florida,USA / Estimations à partir de données satellitales du rayonnement solaire,du rayonnement de grande longueur d’onde et de l’évapotranspiration d’une zone humide de Floride (EUA)

Abstract

Abstract Routine estimates of daily incoming solar radiation from the GOES-8 satellite were compared to locally measured values in Florida. Longwave radiation estimates corrected using GOES-derived cloud amount and cloud top temperature products improved net radiation estimates as compared to a clear sky longwave approach. The Penman-Monteith, Turc, Hargreaves and Makkink models were applied using GOES-derived estimates of solar radiation and net radiation to predict daily evapotranspiration and were compared to evapotranspiration measured with an eddy-correlation system in an emergent wetland experimental site in north-central Florida under unstressed conditions. While the Penman-Monteith model provided the best estimates of evapotranspiration (R ² = 0.92), the empirical Makkink method demonstrated nearly comparable agreement (R ² = 0.90) using only the GOES solar radiation and measured temperature. The results show that it is possible to generate spatially distributed daily potential evapotranspiration estimates using GOES-derived solar radiation and net radiation with limited additional surface measurements.     

三维约束四面体网格的拓扑关系描述

针对约束四面体网格(TEN)拓扑关系描述单一的问题,该文基于拓扑结构和拓扑关系两方面对约束TEN进行了组合拓扑关系描述。借助于点集拓扑理论,传统TEN拓扑关系被重新定义为基本拓扑关系、方向关系和位置关系,其中在位置关系中首次提出了基于矢量的描述方法;基本拓扑关系描述中以体-体关系为例分析了已有的8种拓扑关系,并据此提出了拓扑关系细化与筛选准则,以更准确地描述TEN的拓扑关系。通过分析可知,约束TEN的组合关系描述具有拓扑结构简单、易于描述与实现的特点。     

湖北大冶铁山地区缝合线三维形态模拟及其成因分析

广泛发育于碳酸盐岩中的缝合线构造可以用来分析构造应力方位、计算岩层的有限应变和恢复原始地层厚度;同时,缝合线可以是石油、天然气和地下水的储积场所和运移通道。湖北大冶铁山地区发育有大量的缝合线构造。通过影像云纹法和GIS技术恢复了采自该地区的数枚缝合线标本的三维数字形态。利用该模型对缝合线的尺度、坡角、粗糙度、谷底点分布、二维剖面形态和压溶量等进行了定量分析,完善了缝合线的几何形态学研究并在此基础上对其成因进行了解释,认为铁山地区的缝合线主要由成岩压实作用和压溶作用形成,缝合线在从初始到各种复杂形态的发展过程中主要受两个因素控制：一是岩石的力学性质;二是由主压应力引起的局部应力集中而产生的溶解释放。      

捷克Jílové金矿集区中硒矿物的特征与硒化物-碲化物的形成物理化学条件

捷克Jílové金矿集区在中世纪时期曾是波希米亚地块最大、最富集金的地区,黄金开采已具有2000多年的悠久历史。最重要的矿床有Pepˇr、Bohuliby、Radlík和Rotlev,主要赋存于新元古界těchovice组火山-沉积岩和波希米亚花岗闪长岩深成岩体中。金矿化存在3种类型:脉状矿化、含金网脉状矿化、浸染状矿化。金矿床中的矿物组成已超过70种,包括Cu、Pb、Zn、Fe、As、Mo、Bi、Hg、Au和Ag的一些硫化物、硫盐、氧化物、氢氧化物、硫酸盐、碳酸盐、钨酸盐、硅酸盐,还有碲化物、卤化物和自然元素的矿物。笔者通过显微镜观察、电子探针和扫描分析等综合分析技术,确认金矿床中也存在一些硒矿物。金矿石中的矿物种类较多,组成复杂以及存在大量碲化物、自然金,构成Jílové金矿集区的一大特色。一般说来,亲硫环境越强,出现硒化物、碲化物这样的特殊矿物就越少。因此,金矿床中同时存在大量碲化物、硒化物矿物,表明金矿床的形成具有特殊的物理化学条件。在成矿早阶段,具有高f(S2)和低f(Se2)、f(Te2)、f(O2)的介质,且f(S2)/f(Se2)>1、f(S2)/f(Te2)>1,此时形成大量的黄铁矿、白铁矿、磁黄铁矿、黄铜矿、毒砂、方铅矿、闪锌矿等硫化物。而Se、Te有可能以类质同象的形式赋存于硫化物矿物中。在成矿晚阶段,随着硫化物的大量沉淀,具有f(Se2)/f(S2)、f(Te2)/f(S2)、f(O2)逐渐增高,有利于硒化物、碲化物的形成。根据金矿石中的硒矿物、碲矿物组合,获得在300℃成矿温度下形成硒化物、碲化物时的f(Se2)、f(Te2)分别为10-14.97～10-7.09和10-10.98～10-7.50。