恐龙的晚餐

一只饥饿的恐龙悄悄来到我的家。它已饿了一整天,大大的肚子饿扁扁！     

Electron lenses of hyperbolic field structure

Increasing lens voltage, higher than the incident electron voltage, at first blocks the beam and then converts the electron lens into a curved mirror, the focal properties of which are analyzed.The embodiment of hyperbolic lenses is discussed by means of the boundary conditions which may be rigorously or approximately satisfied in actual designs. The effects of lateral apertures and windows on the imaging qualities of the field are considered in detail.Expressions are derived for velocity-, angular- and aperture-defects, the latter being merely a surface effect of the hyperbolic field. They all depend on a few parameters only of the lens field and are relatively small in magnitude. An experi- mental verification of the field structure with partial compensation of the defects shows favorable imaging qualities.Two-dimensional fields, constituting electron cylinder lenses, are considered in a similar way, leading to analogous formulations for the cardinal properties.     

The comprehension and production of Wh-questions in deaf and hard-of-hearing children

Hearing loss during the critical period for language acquisition restricts spoken language input. This input limitation, in turn, may hamper syntactic development. This study examined the comprehension, production, and repetition of Wh-questions in deaf or hard-of-hearing (DHH) children. The participants were 11 orally trained Hebrew-speaking children aged 9.1-12.4 with moderate-to-profound hearing loss from birth, who consistently used hearing aids or cochlear implants and who had difficulties understanding relative clauses. Experiment 1 tested the comprehension of Wh-questions using a picture selection task, comparing subject with object questions and who- with which-questions; Experiment 2 tested the production of subject and object who-questions using an elicitation task; and Experiment 3 tested the repetition of Wh-questions and other structures derived by Wh-movement. All the DHH participants showed difficulty in the comprehension, production, and repetition of object questions, and their performance was significantly below that of hearing children. In contrast, they repeated embedded sentences without movement well, indicating that their deficit is in syntactic movement rather than embedding or the CP node in the syntactic tree. The results provide additional evidence that DHH children have difficulties with Wh-movement and emphasize that Wh-questions, which are crucial for communication, can be severely impaired in these children.     

重寫人

一、重寫人和报紙的关系作为编輯部內部的工作者,他的許多工作公众很少知道,就是他的报館同事也很少知道。他是寫作工匠,对新聞有特别的了解,并且有可貴的采訪經驗。他是有經驗的記者有些記者在报館內工作比在街上采訪工作得好些。有些記者相反。一个人只要善于了解别人就能找到新聞重要來源的门徑了。可是,他們也許不会組織摘記,不会寫精彩的新聞。如果把他們采訪到的事     

The information requirements and information-seeking behaviours of health and social care professionals providing care to children with health care needs: a pilot study

OBJECTIVES: The objectives of this work were to identify the sources of information currently received, information-seeking behaviours, information requirements and preferences for future information provision amongst health and social care professionals providing care to children with health care needs. METHODS: Data were collected using a cross-sectional postal questionnaire survey. RESULTS: A wide range of information resources was reported as being available to professionals. However, a large proportion of respondents found it necessary to perform additional searches for information, suggesting that current resources were not satisfying their needs. The majority of professionals reported a preference for electronic formats, whilst a smaller proportion preferred hard copy materials. Participants promoted the use of informal networks as a means of support and exchange of information. CONCLUSION: Supplementing the information that is provided in electronic and hard copy formats, by enhancing informal networks, may be the most effective way of meeting the information needs of this group of professionals.     

Standardization of search methods for guideline development: an international survey of evidence-based guideline development groups

BACKGROUND: Effective literature searching is particularly important for clinical practice guideline development. Sophisticated searching and filtering mechanisms are needed to help ensure that all relevant research is reviewed. PURPOSE: To assess the methods used for the selection of evidence for guideline development by evidence-based guideline development organizations. METHODS: A semistructured questionnaire assessing the databases, search filters and evaluation methods used for literature retrieval was distributed to eight major organizations involved in evidence-based guideline development. RESULTS: All of the organizations used search filters as part of guideline development. The medline database was the primary source accessed for literature retrieval. The OVID or SilverPlatter interfaces were used in preference to the freely accessed PubMed interface. The Cochrane Library, embase, cinahl and psycinfo databases were also frequently used by the organizations. All organizations reported the intention to improve and validate their filters for finding literature specifically relevant for guidelines. DISCUSSION: In the first international survey of its kind, eight major guideline development organizations indicated a strong interest in identifying, improving and standardizing search filters to improve guideline development. It is to be hoped that this will result in the standardization of, and open access to, search filters, an improvement in literature searching outcomes and greater collaboration among guideline development organizations.