Stimulus generalization of a positive conditioned reinforcer

Stimulus generalization has been observed for discriminative, eliciting, and emotional functions of stimuli. In our study, in order to investigate the generalization of the reinforcing function of stimuli, pigeons were trained in a Skinner box to peck at an unlighted key to obtain aperiodic, brief exposures of light at a wavelength of 550 mmicro, the positive conditioned reinforcer, which was immediately followed by food reward. Testing in extinction, we obtained generalization gradients for the number of responses and the time the pigeons expended to produce exposures on the unlighted key of 550 mmicro, 530 mmicro) 510 mmicro, or no light. This finding suggests that stimulus generalization occurs with all functions of stimuli.     

Fossil mycorrhizae: a case for symbiosis

Vesicular-arbuscular mycorrhizae are significant in the physiology and ecology of extant vascular plants, and they may also have played a major role in the origin of the vascular land flora. The case for fossil vesicular-arbuscular mycorrhizae rests upon hyphae and chlamydospore-like bodies in several Paleozoic taxa, but fossil arbuscles are unknown to date. Specimens from the Triassic of Antarctica represent the first known occurrence of arbuscles in the fossil record.     

Characterization of compounds that induce symbiosis between sea anemone and anemone fish

The species-specific partnership between the sea anemone and anemone fish in many parts of the Indo-Pacific region is a well-known phenomenon. Chemicals secreted by the sea anemone to elicit symbiotic behavior of the fish have been studied for two host-guest pairs, Radianthus kuekenthali (sea anemone)-Amphiprion perideraion (anemone fish) and Stoichactis kenti-A. ocellaris. A new pyridinium compound, amphikuemin, which induces characteristic attracted swimming (toward the chemical stimulus) in A. perideraion, has been isolated from R. kuekenthali and characterized. Several other chemicals that elicit characteristic symbiotic movements have also been identified.     

Cues: their relative effectiveness as a function of the reinforcer

Two cues, either size or flavor of food pellet, were conditionally paired with either malaise induced by x-ray or pain induced by shock in four groups of rats. The combination of flavor and illness produced as conditioned decrement in consumption, but that of size and illness did not. Conversely, the combination of size and pain produced an inhibition of eating, but flavor and pain did not. Apparently, effective associative learning depends on central neural convergence of the paired afferent input.     

A virus in a fungus in a plant: three-way symbiosis required for thermal tolerance

A mutualistic association between a fungal endophyte and a tropical panic grass allows both organisms to grow at high soil temperatures. We characterized a virus from this fungus that is involved in the mutualistic interaction. Fungal isolates cured of the virus are unable to confer heat tolerance, but heat tolerance is restored after the virus is reintroduced. The virus-infected fungus confers heat tolerance not only to its native monocot host but also to a eudicot host, which suggests that the underlying mechanism involves pathways conserved between these two groups of plants.     

Lectins: a possible basis for specificity in the Rhizobium--legume root nodule symbiosis

Soybean lectin labeled with fluorescein isothiocyanate combined specifically with all but 3 of 25 strains of the soybean-nodulating bacterium Rhizobium japonicum. The lectin did not bind to any of 23 other strains representative of rhizobia that do not nodulate soybeans. The evidence suggests that an interaction between legume lectins and Rhizobium cells may account for the specificity expressed between rhizobia and host plant in the initiation of the nitrogen-fixing symbiosis.     

Lyso-phosphatidylcholine is a signal in the arbuscular mycorrhizal symbiosis

The arbuscular mycorrhizal (AM) symbiosis represents the most widely distributed mutualistic root symbiosis. We report that root extracts of mycorrhizal plants contain a lipophilic signal capable of inducing the phosphate transporter genes StPT3 and StPT4 of potato (Solanum tuberosum L.), genes that are specifically induced in roots colonized by AM fungi. The same signal caused rapid extracellular alkalinization in suspension-cultured tomato (Solanum lycopersicum L.) cells and induction of the mycorrhiza-specific phosphate transporter gene LePT4 in these cells. The active principle was characterized as the lysolipid lyso-phosphatidylcholine (LPC) via a combination of gene expression studies, alkalinization assays in cell cultures, and chromatographic and mass spectrometric analyses. Our results highlight the importance of lysophospholipids as signals in plants and in particular in the AM symbiosis.     

原油储罐清洗方法

介绍了油罐清洗的作业步骤,指出了在油罐清洗过程中应注意的事项和操作要点.认为采用蒸汽熏蒸与干洗相结合的清洗方法对油罐进行清洗,可彻底清除罐内油污,减少原油的损耗,并可缩短施工工期,降低油罐清洗成本,为今后类似油罐清洗工作提供了借鉴.     

基于生态-产业共生关系的林业生态安全测度方法构想

通过对林业生态安全内涵构成的研究和对现有测度方法的比较分析,发现国内外林业生态安全测度研究中存在“就生态论生态”的预警滞后性、评价指标体系及权重设定的主观性、指标体系和特征指数难以优势互补、生态安全性判据缺乏客观依据等问题.为解决这些问题,需要基于生态与产业系统的共生关系研究林业生态安全测度的新方法.首先,研究林业生态安全的压力-状态-影响-响应结构模型和结构方程模型(SEM)的构建方法,从而为评价指标体系的构建和权重的确定提供了理论依据和结构化、定量化方法.然后,通过寻求指标体系和特征指数的有机结合,得出描述林业生态安全演变趋势的性质和程度的特征指数——生态-产业共生度和成熟度.由此提出确定林业生态安全阈值和底线的定量化方法,并建立林业生态安全双特征判断矩阵,从而将林业生态安全度分为3个安全区间、6个安全等级和4个预警级别.最后,综合以上成果,构建了基于生态-产业共生关系的林业生态安全测度方法的整体框架:目标-手段树和技术路线.根据新方法的构建机理,所得出的林业生态安全测度和预警信息具有主观性弱、预测性强、特征指数值的生态经济意义明确、便于追溯问题的原因等技术优势,有利于林业生态安全的监控和管理.     

热媒炉积炭的化学清洗工艺

在管道输送原油的间接加热过程中，热媒的导热油由于长期在高温下使用，会劣化变质，形成积炭，影响热媒炉的传热效率，讨论了热媒炉积炭的成因，形态及化学清洗条件，在介绍了水基复合清洗剂和酸性清洗剂清除积炭化学原理的基础上，给出了清除积炭的施工工艺和注意事项。     

网箱养殖水下清洗装置设计

针对深远海网箱养殖需求,基于高压水射流技术设计了网箱水下自动清洗装置。对清洗装置进行了结构设计,分析了装置的工作原理。根据要求对装置主要参数进行选配分析,设计装置相关性能参数为流量15 L/min、工作压力20 MPa,该清洗装置清洗效率高,综合性能能够满足设计要求。     

气泡对蔬菜的清洗作用及清洗参数模型的建立

气泡溃灭和回弹再生时产生巨大的瞬时压强、气蚀作用和高速微射流以及气流引起水的翻滚、漩涡等复杂的扰动冲击蔬菜时可以有效地清除蔬菜表面的污染物。通过叶类蔬菜清洗试验,确定了蔬菜洗净率y和气流量x1与清洗时间x2的二元线性回归模型y=28.98+1.21x1+8.23x2。验证试验结果表明:当气泡强度在5~25m3/h、清洗时间在1~4m in范围时,试验值和模型值之间的相对误差率在8%以内。     

Developmental biology of a plant-prokaryote symbiosis: the legume root nodule

The development of nitrogen fixing root nodules on the roots of leguminous plants is induced by soil bacteria (for example, from the genus Rhizobium). The formation of this plant organ involves specific activation of genes in both plant and bacterium. Analysis of these genes gives insight into the way in which plant and bacterium succeed in coordinating plant development.     

LysM-type mycorrhizal receptor recruited for rhizobium symbiosis in nonlegume Parasponia

Rhizobium-root nodule symbiosis is generally considered to be unique for legumes. However, there is one exception, and that is Parasponia. In this nonlegume, the rhizobial nodule symbiosis evolved independently and is, as in legumes, induced by rhizobium Nod factors. We used Parasponia andersonii to identify genetic constraints underlying evolution of Nod factor signaling. Part of the signaling cascade, downstream of Nod factor perception, has been recruited from the more-ancient arbuscular endomycorrhizal symbiosis. However, legume Nod factor receptors that activate this common signaling pathway are not essential for arbuscular endomycorrhizae. Here, we show that in Parasponia a single Nod factor-like receptor is indispensable for both symbiotic interactions. Therefore, we conclude that the Nod factor perception mechanism also is recruited from the widespread endomycorrhizal symbiosis.     

原油储罐清淤用的射流器

为防止原油储罐中沉淀物沉积,国外一些公司采用了皮托管射流器系统进行清渣除淤工作。皮托管射流器主要由连接法兰、主体、涡轮、喷嘴、机械主体等构成,其工作原理是被外循环泵压送的原油带动涡轮高速旋转,并同原油主流一起从喷嘴喷出,形成的高速射流随着喷嘴的旋转在罐底板上作360°周期性冲刷,使沉积物扩散到原油中随原油排出。采用皮托管射流器的优点是安全可靠,操作简单,不易形成射流死区,减少排水作业困难,便于实现海底(地下)储罐的清淤渣工作,并能缩短开罐检查的工期,降低清洗、防腐、动力费用,该系统与原油加热相结合还可取代加热盘管。     

清选装置电气控制系统设计

自行研制了纵轴流风筛式清选装置试验台,并对清选装置的电气控制系统进行了设计研究,配有扭矩仪和风速传感器等硬件设备,采用了计算机数据采集与监控系统,可实现数据的实时采集,可以对参数进行实时调节控制,控制面板简洁规范,操作简便。该设计提高了清选装置试验台的操作简便性和试验数据测量的准确性,对于指导清选装置的设计制造具有重要意义。     

油库清罐作业中事故的成因及预防

清罐作业是油库一项经常性的工作,具有较大的危险性.分析了清罐作业中存在的危险因素,提出了清罐作业中预防事故发生的防范措施.