自然颂

坦白的讲,成年人很少能发现大自然。……热爱大自然的人是精神形体和谐统一的人,是已经步入成年却仍童心未泯的人。他与天地间的交流,是他的精神食粮。尽管他的心灵深处确有悲伤,但面对自然,仍是满心喜悦。大自然说,这就是我创造的生灵,任凭他有千种悲哀,只要与我在一起,他就应     

Ubiquitous Computing in the Library:Indiana State University Library s Experience

1 Introduction New technologies and other developments haye changedthe information seeking behaviors of the academic communityand the general public.Nowhere is this more evident than inthe exponential growth of the World Wide Web and cellularphone usage.Responding to these user needs and newtechnologies,libraries are moving from being InformationWarehouses to becoming Information Portals.Full-text     

Improving GIS Consultations： A Case Study at Yale University Library

面向服务的体系结构、对等网络和网格技术的发展为数宇图书馆体系结构的研究和应用带来了新的机遇，使其在开放性和柔性方面的拓展成为可能。下一代数字图书馆应当是能为更多用户服务的、自适性更强的服务组织，它是以联邦模式进行资源库的构建和服务的组织。与传统数字图书馆相比，下一代数字图书馆的体系结构将更为分布和动态，从而适应资源库、元数据和服务所呈现出的高度异构性。     

Disability hate crime: persecuted for difference

This article briefly discusses the long history of violence towards disabled people which sets the context for an analysis of the modern‐day form of violence known as disability hate crime (DHC). People who look or behave differently to others often find themselves victims of violent crimes. The language used to describe disabled people contributes to their diminished position in society. A brief review of definitions of DHC and exploration of news media coverage of the Pilkington and Askew DHC cases are undertaken. Cultural scapegoating of disabled people is discussed. Disabled people are perceived as contributing to their own victimisation, the lack of support afforded to them by society and the failure of systems meant to protect them. As long as disabled people remain outside mainstream society, they are unlikely to achieve the same levels of respect and protection from crime that other groups in society are afforded.     

Successive reversals of a discriminated preference for signaled tailshock

Three rats received unmodifiable tailshock at random intervals in a shuttlebox. In a continuous-choice situation, Ss could choose between an auditory signal immediately preceding or immediately following the tailshock. Over repeated daily 3-h sessions, each S acquired a spatial discrimination indicating a strong preference for the signal preceding tailshock. This preference continued undiminished through two successive reversals of the position associated with signaled shock. This demonstration precludes explanations of the preference-for-signaled-shock phenomenon based upon primary reinforcement value or acquired value of the signal, position preferences, and overt modification of the aversiveness of the reinforcer through such means as postural adjustments. An explanation of recent failures to obtain the preference-for-signaled-shock effect is offered.     

The questionable role of higher education as an occupational screening device

Employers optimally pursue activities which facilitate the coordinating of employee characteristics and the requirements of the job. One allegedly important employee characteristic is the level of education. Employees with higher levels of education are rewarded with higher wages than employees with lower levels. This may occur if higher levels of education make an employee truly more productive or if because of an employer's beliefs only those individuals with higher levels of education are allowed to enter the higher paying positions (occupational screening).The above propositions are testable, depending crucially upon the theoretical model employed for determining occupational choices. We shall compare the implications of two possible occupation choice models: (1) enter the job which offers the highest lifetime income, (2) enter the job which offers the highest level of overall satisfaction. We estimate these two models using the NBER-TH data sample. By distributing our estimated results and the actual distribution of occupations over the education levels of high school, some college and BA we can see if more or less people are expected to enter specific occupations at each education level. Support for screening exists if more people are expected in high status occupations at low education levels than are actually in those occupations.When comparing the estimated results for each model we see different outcomes emerge. The latter indicates that screening does not exist while the former does. We present arguments as to why we feel that the second model is the more correct and appropriate and, consequently, why we feel that education is not an effective screening device.     

Two components of responding in Pavlovian lick suppression

The present research examined the temporal distribution of responding in a lick suppression paradigm. In Experiment 1, rats were trained with either a 30- or a 120-s conditioned stimulus (CS), which was followed either by a footshock (unconditioned stimulus [US]) or nothing. Licking during the CS was suppressed only in the former condition. Suppression was more pronounced early in the CS. In Experiment 2, rats were exposed to two 30-s or two 120-s CSs, with delivery of the shock being contingent on CS1 for half of the animals and on CS2 for the other half. For both the paired and the unpaired conditions, suppression at the beginning of CS1 was observed for all the groups. By discounting the possibility of generalization between CS1 and CS2, it appears that this initial suppression was not a conditioned response to the CS, but an unconditioned one due to mere exposure to the shock US.     

Some determinants of second-order conditioning

In a Pavlovian conditioning situation, an initially neutral stimulus may be made excitatory by nonreinforced presentations in compound with an established conditioned excitor [i.e., second-order conditioning (SOC)]. The established excitor may be either a punctate cue or the training context. In four conditioned suppression experiments using rats, we investigated whether SOC phenomena parallel other cue interaction effects. In Experiment 1, we found that the response potential of a target stimulus was directly related to the intertrial interval when SOC was mediated by a punctate cue, and inversely related to the intertrial interval when SOC was mediated by the training context. Experiment 2 demonstrated that punctate- and context-mediated SOC are oppositely affected by posttraining context extinction, and Experiments 3 and 4 demonstrated that context- and punctate-mediated SOC are differentially affected by conditioned stimulus (Experiment 3) and unconditioned stimulus (Experiment 4) preexposure treatments. These findings parallel phenomena in conditioned inhibition and cue competition situations.