How students reason about matter flows and accumulations in complex biological phenomena: An emerging learning progression for mass balance

In recent years, there has been a strong push to transform STEM education at K-12 and collegiate levels to help students learn to think like scientists. One aspect of this transformation involves redesigning instruction and curricula around fundamental scientific ideas that serve as conceptual scaffolds students can use to build cohesive knowledge structures. In this study, we investigated how students use mass balance reasoning as a conceptual scaffold to gain a deeper understanding of how matter moves through biological systems. Our aim was to lay the groundwork for a mass balance learning progression in physiology. We drew on a general models framework from biology and a covariational reasoning framework from math education to interpret students' mass balance ideas. We used a constant comparative method to identify students' reasoning patterns from 73 interviews conducted with undergraduate biology students. We helped validate the reasoning patterns identified with >8000 written responses collected from students at multiple institutions. From our analyses, we identified two related progress variables that describe key elements of students' performances: the first describes how students identify and use matter flows in biology phenomena; the second characterizes how students use net rate-of-change to predict how matter accumulates in, or disperses from, a compartment. We also present a case study of how we used our emerging mass balance learning progression to inform instructional practices to support students' mass balance reasoning. Our progress variables describe one way students engage in three dimensional learning by showing how student performances associated with the practice of mathematical thinking reveal their understanding of the core concept of matter flows as governed by the crosscutting concept of matter conservation. Though our work is situated in physiology, it extends previous work in climate change education and is applicable to other scientific fields, such as physics, engineering, and geochemistry.     

Technological change in U.S. jet fighter aircraft

This paper quantitatively measures technological change in U.S. jet fighter aircraft from 1944 to the present day using the hedonic pricing approach. The technical and performance characteristics of jet fighters have changed dramatically between the time they were first developed at the beginning of the 1940s and the present. Parallel to this technological change there has been a sharp escalation in costs regarding the new generations of jet fighter aircraft. We estimate a measure of price for the performance and technical characteristics of these aircraft. Embodied technological change in jet fighter airframes is measured using quality-adjusted prices. Although the flyaway cost of jet fighter aircraft has soared, on average, by about 12.63% per year, the quality-adjusted aircraft cost has only risen by about 2.6% per year, a figure lower than the average observed general inflation rate for the period (around 4%). This represents an impressive average technological progress ratio of around 10% per year. A revealed preferences argument shows that the characteristic most valued by the government is stealth capability, followed by advanced avionics.     

Light emitting diodes and the lighting revolution: The emergence of a solid-state lighting industry

Emergence of new industries from evolving technologies is critical to the global economy, yet has been relatively understudied due to the paucity of available data. This study draws lessons on industry emergence, by analyzing how a solid-state lighting (SSL) industry grew out of light emitting diode (LED) technologies that evolved for half a century, with participation by tens of thousands of researchers in universities, national laboratories, and firms. Using data on publications, patents, and firms combined with business history we trace the evolution of SSL through a succession of market niches. At times a few researchers with unorthodox research approaches made breakthroughs that greatly advanced particular technology trajectories and pushed LED research in unexpected directions. A succession of LED market niches advanced the technology and provided profits to incentivize continuing research while reducing cost and improving efficacy of LEDs. Innovating firms developed a thicket of patents and captured substantial profit, but were embroiled in extensive litigation that was ultimately resolved through cross-licensing. A major new generation of lighting products is now disrupting the traditional lighting industry. Although the leading incumbent lighting firms all invested early and heavily in SSL, the industry's future leadership is uncertain.     

专业镇竞争力评价的指标体系与模型构建

<正>确分析和评价专业镇竞争力,客观认识和了解专业镇发展现状及竞争优势,对专业镇的政策制定及转型发展具有重要现实意义。从专业镇竞争力的内涵及评价内容入手,从城镇竞争力、产业竞争力、企业竞争力、自主创新能力和环境竞争力五个方面构建出一套相对完整的专业镇竞争力评价指标体系以及与之相应的评价模型,为客观、全面、定量地评价和衡量专业镇竞争力提供理论支撑和实践依据。     

我国区域公共图书馆文化服务效率评价及差异分析

[目的/意义]旨在提高我国公共图书馆文化服务效率,为公共图书馆文化服务发展提供参考。[方法/过程]以我国31个省份公共图书馆为数据,运用DEA-BCC模型和K-means聚类分析我国各区域文化服务的效率及差异。[结果/结论]我国公共图书馆文化服务效率整体较低,呈非均衡性,存在不同程度投入冗余和产出不足,最后针对我国公共图书馆文化服务提出相应的改进建议。     

Learning whom not to trust across early and middle adolescence: A longitudinal neuroimaging study to trusting behavior involving an uncooperative other

Longitudinal changes in trusting behavior across adolescence and their neural correlates were examined. Neural regions of interest (ROIs) included the medial prefrontal cortex (mPFC), dorsal anterior cingulate cortex (dACC), left anterior insula (AI), bilateral ventral striatum (VS), and right dorsal striatum (DS). Participants (wave 1 age: M = 12.90) played the investor in a Trust Game with an uncooperative trustee three times (1-year interval). Analyses included 77 primarily Dutch participants (33 females). Participants decreased their investments with wave. Furthermore, activity was heightened in mPFC, dACC, and DS during investment and repayment, and in right VS (investment) and AI (repayment). Finally, DS activity during repayment increased with wave. These findings highlight early–middle adolescence as an important period for developing sensitivity to uncooperative behavior.     

Association between self-reported health and physical and/or sexual abuse experienced before age 18

OBJECTIVE: The present study evaluated the association between women's health and physical and sexual abuse suffered before age 18. METHODS: A total of 3,568 randomly sampled insured women ages 18-64 completed a telephone interview to assess history of physical only, sexual only, or both physical and sexual abuse before age 18 (Behavioral Risk Factor Surveillance System); and current health (Short Form-36, Center for Epidemiologic Studies-Depression, Presence of Symptoms surveys). Adjusted analyses compared the health of women with physical abuse only, sexual abuse only, or physical and sexual abuse to the health of women without these abuse histories. RESULTS: Poorest health status was observed in women with a history of both physical and sexual child abuse compared to women without these abuse histories. In models that adjusted for age and income, women with both abuse types had increased prevalence of depression (prevalence ratio, 2.16), severe depression (PR, 2.84), physical symptoms (PR range, 1.33 for joint pain to 2.78 for nausea/vomiting), fair/poor health (PR, 1.84), and lower SF-36 scores (3.15-5.40 points lower). Women with physical abuse only or sexual abuse only also had higher prevalence of symptoms and lower SF-36 scores but the associations were not as strong. CONCLUSIONS: This study adds to the literature showing a graded association between multiple adverse events in childhood and adult health.     

The relationship between listening styles and conversational sensitivity

This study examines the relationship between the listening styles people tend to employ habitually and related levels of conversational sensitivity. Conversational sensitivity deals with the extent to which people enjoy listening in social interaction, can identify hidden meaning in conversations, and generally are highly aware of implicit messages that may be gained from conversations. One way in which conversational sensitivity might be apparent is in the listening styles which people rely on habitually. Conversationally sensitive receivers may favor one or two listening styles over others. The results indicate a positive relationship between the People listening style and conversational sensitivity, as well as weaker positive relationships between the Content and Action styles and sensitivity. Conversationally sensitive people are most likely to employ the People listening style. The results illustrate the conversational advantages of employing a People listening style.