分布式环境中的编程艺术

分布式数据中心是实现云计算的物理与技术保证。Berkeley计算机系教授David A．Patterson提出,以服务为核心的需求促使分布式数据中心产生,如果说计算以数据中心的模式进行的话,那么,它的指令、它的语言是什么呢？     

Proactive interference in the retention of “attentional sets” in pigeons

In Experiment 1, six groups of pigeons (n=8) were tested for wavelength generalization either immediately or 24 h after learning a successive discrimination, with 550 nm reinforced and a black vertical line extinguished. The groups differed in the stimulus present during single stimulus pretraining, which was 550 nm (pretrain S+), the vertical Une (pretrain S?), or a neutral dim white light (pretrain Sn), respectively. The three immediate generalization gradients were steep and indistinguishable, reflecting only the immediately preceding discrimination training condition. The three delay gradients were flatter, with the flattening particularly marked in the pretrain S? group. This was interpreted as proactive interference (PI) resulting from the memory that both the 550-nm and the line stimuli had previously been reinforced. In Experiment 2, two (TD) groups of pigeons (n=16) were given single stimulus training with a 555-nm keylight followed by eight sessions of discrimination training with two line angles, then one session of non-differential (ND) training with the same two lines, and then a wavelength generalization test either immediately or after a 24-h delay. Two other (hold) groups (n=16) received similar training, except for the TD Une angle training sessions, in these hold groups, the wavelength gradient was flatter in a delayed test; in the TD groups it was steeper, indicating PI from the prior TD training. These two experiments suggest that the “attentional sets,” which purportedly result from TD and ND training, may fruitfully be viewed as target memories subject to the principles of interference theory.     

NURTURING EARLY CHILDHOOD PROFESSIONALISM: THE RHODE ISLAND EARLY CHILDHOOD SUMMER INSTITUTE

This article describes the independent study project of a student who was a graduate assistant in a child development laboratory preschool when Hurricanes Katrina and Rita struck the Gulf Coast area. Through her experiences with “Project Katrina” she deepens her understanding of developmentally appropriate practices as she learns firsthand about the project approach and writing an article for publication in a professional journal.     

Congruence between mother and handicapped child's view of the child's sense of adjustment

The responses of 22 physically handicapped children to selected items of the Piers‐Harris Self Concept Scale for Children were compared with their mothers’ responses to equivalent items of the Personality Inventory for Children. The direction of the responses, whether children were more or less positive in self‐evaluation than mothers perceived them to. be, was analyzed with respect to sex of child, type of school attended, and diagnosis of handicap (cerebral palsy or spina bifida). Only diagnosis of handicap was significantly related to the tendency for children to be either less or more positive in response to the items than their mothers, with cerebral palsy children more positive and spina bifida children consistently less positive in direction. Possible explanations are considered, with particular reference to the children's views regarding peer relationships.