Effect of cortisone or triiodothyronine administration to pregnant rats on lysosomal hydrolases in fetal forebrain and cerebellum

Triiodothyronine injected daily to pregnant rats for the last week of gestation (50 microgram/100 g b.wt) increased the specific activities of 5 acid glycosidases in the fetal forebrain and cerebellum. Cortisone (50 mg/100 g b.wt) administered in the same period had no effect on cerebellum acid hydrolases, but decreased their activity in the forebrain.     

Effect in vivo of norepinephrine on the membrane resistance of brown fat cells

Résumé La dépolarisation de la membrane des cellules adipeuses brunes, produite par l'administration in vivo de noradrénaline, est aussi accompagnée d'une augmentation de la perméabilité mesurée par une augmentation de la résistance membranaire.

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Supported in part by research grant NASA No. NGR-05-004-035.     

Genetic tracing reveals a stereotyped sensory map in the olfactory cortex.

The olfactory system translates myriad chemical structures into diverse odour perceptions. To gain insight into how this is accomplished, we prepared mice that coexpressed a transneuronal tracer with only one of about 1,000 different odorant receptors. The tracer travelled from nasal neurons expressing that receptor to the olfactory bulb and then to the olfactory cortex, allowing visualization of cortical neurons that receive input from a particular odorant receptor. These studies revealed a stereotyped sensory map in the olfactory cortex in which signals from a particular receptor are targeted to specific clusters of neurons. Inputs from different receptors overlap spatially and could be combined in single neurons, potentially allowing for an integration of the components of an odorant's combinatorial receptor code. Signals from the same receptor are targeted to multiple olfactory cortical areas, permitting the parallel, and perhaps differential, processing of inputs from a single receptor before delivery to the neocortex and limbic system.     

Cognitive psychology: rare items often missed in visual searches

Our society relies on accurate performance in visual screening tasks--for example, to detect knives in luggage or tumours in mammograms. These are visual searches for rare targets. We show here that target rarity leads to disturbingly inaccurate performance in target detection: if observers do not find what they are looking for fairly frequently, they often fail to notice it when it does appear.     

电子学艺术 第二版

本书被公认为是有关模拟与数字电子学线路设计的权威性教课书与参考书。本书第一版出版后即在世界范围销售了12．5万册，并且被翻译成8种文字。作者通过实际使用的方法来革命化电子学的教学，即将基本定律、经验方法与窍门相结合，在很大程度上采取非数学处理，鼓励线路直觉、奇思妙想以及线路数值与性能的简单计算。第二版是经过彻底修改与更新的，完全重写有关微计算机和微处理器的章节，通过对有关数字电子学、运算放大器与精确设计和构建技术的具体修订，来回应电子学中极其危险的变化步伐。第二版对每一张表格都做了修订，还增加了许多新的表格。本书的第一作者是美国哈佛大学的物理教授，第二作者是Rowland科学研究所的电气工程主任，他曾在哈佛大学设计了一百多种电子科学仪器。     

Membrane permeability changes duringRana oocyte maturation

A transition from an open system to a closed one must occur during the complex process of meiotic maturation of the amphibian oocyte. Membrane permeability to urea inRana oocytes following progesterone stimulation was determined, and the largest decrease was found to coincide with germinal vesicle breakdown. These findings suggest that the timing of the disappearance of membrane permeability correlates with developmental events that prepare the oocyte for a hostile environment.