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.     

Reaction time as a function of the cardiac cycle in young adults

Simple reaction times to auditory stimuli varied with the phase of the cardiac cycle in which the stimuli were presented, tending to be fastest to stimuli presented during the P-phase of the electrocardiogram. One hundred reaction times obtained from each of 56 men and women between the ages of 20 and 30 years were analyzed.     

Predation through geological time: evidence from gastropod shell repair

Warm-water marine gastropods from soft-bottom habitats show an increase in the incidence of breakage-resistant shell characteristics over geological time. The hypothesis that breakage became a more important component of selection in the middle of the Mesozoic Era is supported by the finding that frequencies of breakage-induced shell repair increased from the Pennsylvanian and Triassic periods to the Cretaceous, Miocene, and Recent.     

Cholinergic sensitivity: normal variability as a function of stimulus background

The sensitivity of the normally innervated iris sphincter to its neuro-transmitter, acetylchloline, and to relatd agents varies inversely with the preexisting physiological stimulus background, that is, the environmental light intnsity. This normal variability suggests the existence of a negative feedback mechahnism whereby sensitivity of the effector cell is modutlated by a product of neuronal activity.     

Vestibulospinal reflexes as a function of microgravity

The idea that sustained microgravity will result in altered otolith input requiring a modification of postural control was explored by using the pathway that links the otolith organs and spinal motoneurons. Two related methods were used. First, the Hoffmann reflex was used to measure at specific times the excitability of the soleus-spinal motoneuron pool during a brief unexpected linear acceleration. Second, extensive dynamic postural testing with a moving platform was done before and after flight. The Hoffmann reflex amplitude, reflecting otolith-modulated motoneuron sensitivity, was low in flight after adaptation, and its postflight potentiation may have been dependent on rate of adaptation. The strength of inflight motion sickness symptoms was related to postflight Hoffmann reflex amplitude. Dynamic posture tests showed significant deviations from the results obtained before flight. The strategy used for balance on the moving platform was modified, and the behavior of the subjects suggested a decrease in awareness of the direction and magnitude of the motion.     

Information as a thermodynamic function of a living system

It is suggested to introduce an information term into the Gibbs thermodynamic equation in the case of living systems. The possibility of describing the behavior of organisms by means of such an approach is shown.     

Sedimentary phosphate method for estimating paleosalinities: a paleontological assumption

Paleosalinity values in certain rocks determined by the sedimentary phosphate method differ from salinity estimates based upon contained fossil assemblages, geochemical methods, and existing stratigraphic controls. Some anomalous values are related to the abundance of fossil organisms known to be concentrators of calcium phosphate. Because of the abundance and diversity of organisms which might introduce significant errors into paleosalinity estimates, the sedimentary phosphate method seemingly is of limited applicability.     

Cell sorting: automated separation of mammalian cells as a function of intracellular fluorescence

A system for high-speed sorting of fluorescent cells was able to sort mouse spleen cells from Chinese hamster ovarian cells after development of fluorochromasia. Highly fluorescent fractions separated after similar treatment from mouse spleen cells immunized to sheep erythrocytes were enriched in antibody-producing cells by factors of 4 to 10.     

Ectodermal Wnt function as a neural crest inducer

Neural crest cells, which generate peripheral nervous system and facial skeleton, arise at the neural plate/ectodermal border via an inductive interaction between these tissues. Wnts and bone morphogenetic proteins (BMPs) play roles in neural crest induction in amphibians and zebrafish. Here, we show that, in avians, Wnt6 is localized in ectoderm and in vivo inhibition of Wnt signaling perturbs neural crest formation. Furthermore, Wnts induce neural crest from naive neural plates in vitro in a defined medium without added factors, whereas BMPs require additives. Our data suggest that Wnt molecules are necessary and sufficient to induce neural crest cells in avian embryos.     

Multiplicity reactivation as a test for recombination function

Multiplicity reactivation of bacteriophage inactivated by ultraviolet light is dependent on the recombination function of either the host bacterial cell or the infecting bacteriophage. Absence of both recombination systems leads to a loss of multiplicity reactivation.     

Grand banks and j-anomaly ridge: a geological comparison

Geological and geophysical evidence supports the hypothesis that the J-anomaly ridge was a part of the Grand Banks in (late) Early Cretaceous time.     

纸坊沟小流域3种景观功能类型的动态变化研究

【目的】统计分析纸坊沟流域3种景观功能类型的动态变化过程,为流域治理效果评价和进一步的景观格局优化提供依据。【方法】以纸坊沟流域1982,1990,2005和2009年的景观斑块图为基础,应用GIS技术对其进行数字化,运用景观生态学原理建立纸坊沟流域景观分类系统,对流域景观进行分类并统计各类型景观指数,分析流域景观功能类型在不同治理时期的动态变化。【结果】(1)利用建立的景观分类系统,可将纸坊沟流域景观划分为生态防护型、经济生产型和生活服务型3种功能类型;根据人类活动对景观的影响,又可将其划分为人类主导景观和自然景观。(2)各个治理时期,生态防护型景观斑块的数量、面积及周长均最大,是流域的主导景观;生态防护型景观形状最复杂,表明其受到的人类干扰最小;生活服务型景观的斑块密度和边缘密度最大,其景观破碎化程度高;人类主导景观的数量、面积占流域景观的半数以上。(3)不同治理时期生态防护型景观斑块面积持续增加,经济生产型景观面积相对减少,各景观功能类型的景观形状指数和分维数增加;自然景观与人类主导景观斑块数量与面积比例随时间推移而减小。【结论】国家各项政策措施使人类对脆弱生态系统的干扰减弱,生态系统得以休养生息,其内因演替逐渐得以增强。     

压裂液在火山岩不同类型孔隙中的分布特征——以新疆西泉井区火山岩油藏为例

火山岩毛细管压力强,渗吸作用明显,明确火山岩渗吸规律对提高火山岩油藏采收率具有至关重要的作用.基于核磁共振技术,对新疆西泉井区火山岩油藏岩样开展渗吸作用下压裂液分布特征试验研究,通过监测静态自发渗吸过程中压裂液在火山岩岩样不同类型孔隙中的分布状况,分析了自发渗吸过程中油水变化特征,定量表征了不同孔隙在渗吸过程中的渗吸速率和采出贡献率.试验结果表明,火山岩发生自发渗吸作用的主要孔隙为毛细管束缚孔隙,孔隙区间为0.0017～0.0365μm;渗吸作用前14h毛细管束缚孔隙渗吸速率大,14h后渗吸速率逐渐减小,38h后渗吸作用基本结束,毛细管束缚孔隙渗吸速率与渗吸时间符合乘幂函数关系;毛细管束缚孔隙最终采收率较可动流体孔隙最终采收率高,毛细管束缚孔隙为渗吸产油主要贡献孔隙,在渗吸作用中占有主要地位.该研究结果对于火山岩油藏压裂后焖井优化有一定的指导意义,可为火山岩油藏高效开采提供一定的理论基础.     

Geochronology: New techniques provide knowledge of the time and mode of formation and subsequent evolution of rock systems

In summary, it now seems possible to obtain accurate ages for many of the common rock types. When rocks have been affected by metamorphic episodes after the time of crystallization, it is possible to recognize this from the age values and, in some cases, to date both the time of crystallization and the time of metamorphism. Work is under way that will make it possible to draw accurate geochronological maps of the continents. An impressive regularity is already evident in the map for North America. Knowledge of the temporal and areal distribution of ages should have an important bearing on theories of the origin of continents and of mountain-building processes (50).