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The purpose of this study was to explore patterns of within-group variability in the emergent literacy skills of preschoolers who are at risk for academic difficulties. We used the person-centered approach of cluster analysis to identify profiles of emergent literacy skills, taking into account both oral language and code-related skills. Participants were 492 preschoolers (aged 42-60 months) enrolled in needs-based programs. In the fall of the academic year, children were administered eight measures of emergent literacy: four oral language measures (i.e., expressive and receptive grammar, expressive and receptive vocabulary) and four code-related measures (i.e., print concepts, alphabet knowledge, name writing, and rhyme). Controlling for age, hierarchical-agglomerative and K-means cluster analysis procedures were employed. Five psychometrically sound profiles emerged: highest emergent literacy (prevalence = 14%); three profiles with average oral language and differential code-related abilities (16%, 24%; 23%); and lowest oral language with broad code-related weaknesses (23%). Profiles were then compared on midyear teacher ratings of emergent literacy as well as end-of-kindergarten literacy performance; results provided convergent evidence of predictive validity. This study highlights the considerable heterogeneity of emergent literacy abilities within an “at-risk” group. The resulting profiles have theoretical and practical relevance when examining both concurrent relationships between oral language and code-related skills as well as longitudinal relationships between early patterns of performance and later reading achievement.  相似文献   
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The mechanism and criterion of crack initiation and propagation of rocks were investigated by many researchers,And the creep behaviour of rocks was also theoretically and experimentally studied by some scientists and engineers.The characteristics of crack initation and propagation of rocks under creep condition.however,are very improtant for rock engineering and still not paid enough attention by researchers,In this paper,the criterion and mechanism of crack initiation and propagation under creep condition were investigated using specimens collected from sandstone rock formations outcropping in the Emei Mountain,the Sichuan Province of China.Cuboid specimens under three point bending were used in this investigation.All specimens were classified into four sorts and used for Mode-I fracutre of creep frcture tests.The experimental result shows that due to creep deformation.rock crack will inevitably initialt and propagate under a load of KI,which is less than fracture toughness KIC but not less than a constant(marked as KIC2),KIC2 indicates the ability of rock to resist crack initiation and propagation under creep conditions and is less than fracture tough ness KIC.defined as creep fracture toughness in this paper,KIC2 should be considered as an importnat parameter on design and computation of rock engineering.The microstructureal mechanism for crack initiation and propagation of rock materials under creep condition was introduced based on competitive model between softening effect and hardening effect,and the validity of test result was explained.The test result was also verified in rheological theory.When KI is more than KIC2 but less than KIC,rock crack will initiate and propagate after a time interval of sustained loading under creep condition.In order to find the relation between duration of sustained lading.which can lead to crack initiation and propagation,and the initial stress intensity factor KI,an unequal0interval time sequence forecasting and predicting model was introduced,and the relation was obtained for homogeneous and isotropic fine-grained red sandstone.Finally a modified fracture toughness formula was given,in which the influence of fracture process zone(FPZ) was fully considered.  相似文献   
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Two groups of albino rats were trained on a simultaneous pattern discrimination task, one with a classical procedure in which the discriminanda remained invariant throughout training, and the other with a fading procedure in which the final task was approached through a series of graduated steps. In a subsequent reversal stage, during which the initial positive stimulus became negative and vice versa, each group was subdivided so that half of the subjects in each original group received reversal training with the same procedure as during acquisition and the other half with the other method. Fading procedures yielded a more proficient performance on every occasion, independently of experimental stage or previous learning history. Results are analyzed in terms of favorable conditions offered by the procedure itself and of beneficial influences exerted over subsequent learning.  相似文献   
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This study examined social, emotional, and cognitive characteristics of American and Chinese children's narratives. Twenty-four American and 26 Chinese 6-year-old children participated. Each child was interviewed individually twice with a 1-week delay interval. During the two interviews, children were asked to tell 11 stories prompted by pictures and standard verbal leads and to recount 7 emotional memories. Content analyses were performed on children's stories and memories. In line with predictions, findings indicated that compared with American children, Chinese children showed greater orientation toward social engagement, greater concern with moral correctness, greater concern with authority, a less autonomous orientation, more expressions of emotions, and more situational details in both their stories and memories. A few gender differences were found. Findings are discussed in terms of different value systems and early socialization practices in these two cultures.  相似文献   
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The study examined whether schools for the deaf were providing services to assist parents in communicating with their children about sexuality (including sexual signs) and whether parents were involved in the sexuality education curriculum within their child's school. The Sexuality Curriculum Questionnaire for Educators of Students Who Are Deaf (Getch & Gabriel, 1998) was completed by 71 educators teaching sexuality curricula in schools for the deaf across the United States. Results indicated that parents were more likely to be involved in approval and development of their children's sexuality education than to receive assistance with sexuality education from the schools. Although the level of parental participation in curriculum development and approval is encouraging, the number of parents actually participating in curriculum development and approval remains low.  相似文献   
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Trade in Australian education services has expanded rapidly over recent years. The sector is the third largest exporter of Australian services. In 2001–2002, exports of education were about $A 4.2 billion. Government assistance to the sector includes export market development, regulation of education standards, and funding education activities; university research and development, for example. This paper examines the case for further government intervention in the export of education, and the appropriate forms of assistance if further government intervention is justified. The paper predominately focuses on assisting higher education exports because this activity dominates education exports.  相似文献   
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