The jamming avoidance response in the weakly electric fishEigenmannia

This study analyzes the algorithm by which the animal's nervous system evaluates spatially distributed temporal patterns of electroreceptive information. The outcome of this evaluation controls the jamming avoidance response, which is a shift in the animal's electric organ discharge frequency away from similar foreign frequencies. The encoding of “behaviorally relevant” stimulus variables by electroreceptors and the central computation of their messages are investigated by combined behavioral and neurophysiological strategies.     

Magnetic compass orientation in birds and its physiological basis

A current model suggests that magnetoreception of compass information starts with light-dependent primary processes. Light-dependency of magnetoreception is supported by behavioral experiments with homing pigeons and caged migratory birds. Three passerine species showed normal orientation under dim monochromatic light from the blue-green range of the spectrum, while they were disoriented under yellow and red light. A sevenfold increase in intensity and pre-exposure to specific wavelengths caused changes in behavior. The behavioral data indicate a complex relationship between the wavelength of light and magnetoreception, suggesting the involvement of more than one type of receptors. Extracellular recordings from the nucleus of the basal optic root and the tectum opticum identified units that responded to changes in magnetic North. Each unit showed a peak in a distinct spatial direction, so that the input of these units, processed collectively and integrated, would indicate compass directions.     

The immunoglobulin-like genetic predetermination of the brain: the protocadherins, blueprint of the neuronal network

The morphogenesis of the brain is governed by synaptogenesis. Synaptogenesis in turn is determined by cell adhesion molecules, which bridge the synaptic cleft and, by homophilic contact, decide which neurons are connected and which are not. Because of their enormous diversification in specificities, protocadherins (pcdh!, pcdh#, pcdh%), a new class of cadherins, play a decisive role. Surprisingly, the genetic control of the protocadherins is very similar to that of the immunoglobulins. There are three sets of variable (V) genes followed by a corresponding constant (C) gene. Applying the rules of the immunoglobulin genes to the protocadherin genes leads, despite of this similarity, to quite different results in the central nervous system. The lymphocyte expresses one single receptor molecule specifically directed against an outside stimulus. In contrast, there are three specific recognition sites in each neuron, each expressing a different protocadherin. In this way, 4,950 different neurons arising from one stem cell form a neuronal network, in which homophilic contacts can be formed in 52 layers, permitting an enormous number of different connections and restraints between neurons. This network is one module of the central computer of the brain. Since the V-genes are generated during evolution and V-gene translocation during embryogenesis, outside stimuli have no influence on this network. The network is an inborn property of the protocadherin genes. Every circuit produced, as well as learning and memory, has to be based on this genetically predetermined network. This network is so universal that it can cope with everything, even the unexpected. In this respect the neuronal network resembles the recognition sites of the immunoglobulins.     

氯咪巴唑在鱼体的富集和代谢动力学

选取中国南方地区典型生物尼罗罗非鱼作为受试生物,将其置于氯咪巴唑含量为2.00ng/mL的水体中暴露7d,考察氯咪巴唑在罗非鱼体内不同部位（鳃、肝脏、胆汁和血浆）的吸收和清除动力学过程,比较了氯咪巴唑在鱼体内不同部位的吸收和清除动力学速率.罗非鱼暴露于氯咪巴唑水溶液3d后,鱼体鳃、肝脏、胆汁和血浆中的氯咪巴唑达到最高浓度,分别为2.91ng/g,33.7ng/g,4.84ng/mL和2.58ng/mL;结束暴露3d后,氯咪巴唑在鳃、胆汁和血浆中的稳定浓度低于方法检测限,在肝脏中的稳定浓度为1.28ng/g.鱼体鳃、肝脏、胆汁和血浆中氯咪巴唑的吸收动力学常数k_u分别为0.069,0.813,0.286和0.136h^-1;清除动力学常数k_e分别为0.033,0.029,0.082和0.060h^-1;半衰期t_1/2分别为21.1,23.9,8.51和11.6h.氯咪巴唑在罗非鱼体内的吸收/清除动力学过程均符合伪一级动力学方程,方程的相关系数r²范围为0.75~0.98.氯咪巴唑在鱼体鳃、肝脏、胆汁和血浆中的稳态生物富集系数对数值logBCF_ss分别为0.50,1.56,0.72和0.45,低于氯咪巴唑在野生罗非鱼体内的富集系数.     

恢复生态学的理论基础、关键技术与应用前景

从群落自然演替的理论出发,指出生态系统的退化并不是不可逆的。恢复生态学阐述了在被破坏的生态系统自然演替的过程中,可以通过人为手段加以调控,改变演替的方向和速度,缩短生态恢复的时间过程的理论。作者指出生态恢复并不一定恢复原状,而是根据自然和社会条件恢复或重建生态系统的结构和功能,并使之达到自维持状态。生物种类及其生长介质的丧失或改变是影响生态恢复的主要障碍,因此,提出选择适合植物种类改造介质和利用物理、化学方法直接改良介质等生态恢复的关键技术。根据我国现实的环境、社会、经济情况提出生态恢复工程技术产业化的问题,并列举了详细数据和成功的范例     

The effect of specimen size,shape, and orientation on dry deposition to galvanized steel surfaces

Galvanized steel specimens varying in size, shape, orientation angle and previous exposure history (weathered specimens) were exposed at Research Triangle Park, NC, in the absence of natural precipitation. The soluble corrosion products were assumed to represent the effects of dry deposition of airborne substances. The statistical analysis of their variability in relation to atmospheric conditions suggested that these substances included sulfur dioxide, nitric acid, hydrochloric acid, and calcium (presumably from coarse particles). The specimen characteristic most influencing inferred dry deposition was previous exposure history. Deposition of gases depended on surface condition (wetness), wind speed, temperature, and to a lesser extent, orientation angle. Deposition of particles depended on orientation angle. Loss of soluble zinc from specimens varied with specimen size to the −0.2 power, even though Reynolds numbers based on average wind speeds and specimen length were well below those classically expected to produce turbulent flow.     

Forest carbon management,the greenhouse effect and electric utilities

Electric utilities in the US have initiated forestry projects to conserve energy and to offset carbon dioxide (CO₂) emissions. In 1995, 40 companies raised US$2.5 million to establish the non-profit UtiliTree Carbon Company which is now sponsoring eight projects representing a mix of rural tree planting, forest preservation, forest management and research efforts at both domestic (Arkansas, Louisiana, Mississippi, and Oregon) and international sites (Belize and Malaysia). The projects include extensive external verification. Such forestry projects — properly documented, monitored and verified — should be a component of domestic and international strategies to address greenhouse gas (GHG) emissions, due to GHG benefits, cost-effectiveness and many other environmental benefits (e.g., related to habitat, erosion and biodiversity). These projects on average are projected to manage CO₂ at a cost of about US $1 per ton. Experts have determined through a series of technical workshops and projects that GHG benefits can be accurately quantified for most types of forestry projects and, in fact, forestry projects in general present no greater challenges than energy-related projects. Near-term policy decision-making related to CO₂ management via forestry is discussed.