宇宙中温度最低点

To an Eskimo(爱斯基摩人), the saying goes, hell is a very cold place, not a hot one. Now NASA and European astronomers have pictures of Eskimo hell: the coldest spot in the known universe. The place is 5, 000 light-years from Earth in the constellation Centaurus(人马座). It' s the Boomerang Nebula: a cloud of gases that are being expelled from a dying star.     

International Student Achievement Comparisons and US STEM Workforce Development

Journal of Science Education and Technology - Comparisons of US student achievement to other countries, conducted since the 1960s, have received extensive media coverage in the USA. Policy studies...     

Pacific CRYSTAL Project: Explicit Literacy Instruction Embedded in Middle School Science Classrooms

Science literacy leading to fuller and informed participation in the public debate about science, technology, society, and environmental (STSE) issues that produce justified decisions and sustainable actions is the shared and central goal of the Pacific CRYSTAL Project. There is broad agreement by science education researchers that learners need to be able to construct and interpret specific scientific discourses and texts to be literate in science. We view these capabilities as components in the fundamental sense of science literacy and as interactive and synergetic to the derived sense of science literacy, which refers to having general knowledge about concepts, principles, and methods of science. This article reports on preliminary findings from Years 1, 2, and 3 of the 5-year Pacific CRYSTAL project that aims to identify, develop, and embed explicit literacy instruction in science programs to achieve both senses of science literacy. A community-based, opportunistic, engineering research and development approach has been utilized to identify problems and concerns and to design instructional solutions for teaching middle school (Grades 6, 7, and 8) science. Initial data indicate (a) opportunities in programs for embedding literacy instruction and tasks; (b) difficulties generalist teachers have with new science curricula; (c) difficulties specialist science teachers have with literacy activities, strategies, genre, and writing-to-learn science tasks; and (d) potential literacy activities (vocabulary, reading comprehension, visual literacy, genre, and writing tasks) for middle school science. Preinstruction student assessments indicate a range of challenges in achieving effective learning in science and the need for extensive teacher support to achieve the project’s goals. Postinstructional assessments indicate positive changes in students’ ability to perform target reading and writing tasks. Qualitative data indicate teachers’ desire for external direction and the need for researchers to expand the literacy framework to include oral discourse. A case study of teachers’ use of a specific literacy task and its influence on students revealed indications of robustness and effectiveness. Experiences revealed procedural difficulties and insights regarding community-based research and development approaches.     

Characteristics of School Districts That Participate in Rigorous National Educational Evaluations

Given increasing interest in evidence-based policy, there is growing attention to how well the results from rigorous program evaluations may inform policy decisions. However, little attention has been paid to documenting the characteristics of schools or districts that participate in rigorous educational evaluations, and how they compare to potential target populations for the interventions that were evaluated. Utilizing a list of the actual districts that participated in 11 large-scale rigorous educational evaluations, we compare those districts to several different target populations of districts that could potentially be affected by policy decisions regarding the interventions under study. We find that school districts that participated in the 11 rigorous educational evaluations differ from the interventions' target populations in several ways, including size, student performance on state assessments, and location (urban/rural). These findings raise questions about whether, as currently implemented, the results from rigorous impact studies in education are likely to generalize to the larger set of school districts—and thus schools and students—of potential interest to policymakers, and how we can improve our study designs to retain strong internal validity while also enhancing external validity.     

Neural adaptations with sport-specific resistance training in highly skilled athletes

The aim of this study was to assess the effects of variations in the volume and intensity of resistance training in highly skilled athletes on neural adaptive mechanisms: the maximality and pattern of neural drive. The maximality of muscle activation was measured using a high-resolution sample and hold amplifier to record interpolated twitches. The pattern of neural drive was measured by analysing isometric torque-time curves and electromyographic (EMG) characteristics during the performance of rapid isometric contractions at maximal effort. The volume and intensity of training were varied at 4-weekly intervals to systematically emphasize the development of strength, power and motor performance in 14 highly skilled track and field athletes (e.g. discus, hammer, javelin, shot put and weight). Knee extension strength increased significantly by 15% during steady maximal isometric contractions and by 24% during rapid isometric contractions at maximal effort after the 16-week training programme (P < 0.05). Increases in EMG amplitude and rate of EMG activation indicated that improvements to the pattern of neural drive occurred with sport-specific resistance training (P < 0.05). The maximality and pattern of neural drive did not change in the control group.     

The magnitude and prevalance of significant regressed discrepancies at common test values

An initial criterion to determine severe discrepancies and relative strengths and weaknesses is a significant difference between regressed standard scores. Tables are presented as a convenient method to determine the magnitude of a discrepancy required for significance at common reliability and inter-correlation values. Prevalences of significant discrepancies are also shown, indicating that significant discrepancies are not uncommon in a normal population.