Using digital images of the zebra finch song system as a tool to teach organizational effects of steroid hormones: a free downloadable module

Zebra finch song behavior is sexually dimorphic: males sing and females do not. The neural system underlying this behavior is sexually dimorphic, and this sex difference is easy to quantify. During development, the zebra finch song system can be altered by steroid hormones, specifically estradiol, which actually masculinizes it. Because of the ease of quantification and experimental manipulation, the zebra finch song system has great potential for use in undergraduate labs. Unfortunately, the underlying costs prohibit use of this system in undergraduate labs. Further, the time required to perform a developmental study renders such undertakings unrealistic within a single academic term. We have overcome these barriers by creating digital tools, including an image library of song nuclei from zebra finch brains. Students using this library replicate and extend a published experiment examining the dose of estradiol required to masculinize the female zebra finch brain. We have used this library for several terms, and students not only obtain significant experimental results but also make gains in understanding content, experimental controls, and inferential statistics (analysis of variance and post hoc tests). We have provided free access to these digital tools at the following website: http://mdcune.psych.ucla.edu/modules/birdsong.     

2002-2012年达累斯萨拉姆城市蔓延特征及影响因素

以坦桑尼亚首位城市达累斯萨拉姆2002、2007和2012年土地利用分类数据为基础,结合实地调研,运用扇形分析和同心圆分析等方法,以及用地增长弹性系数、扩展强度指数、紧凑度、分形维数等指标,研究达累斯萨拉姆近年来城市蔓延的总体态势和空间格局特征。研究结果表明：1）2002-2012年间达累斯萨拉姆城市蔓延特征明显,蔓延程度较高,蔓延速度不断加快,主要表现为非正式聚落不断增长情况下的城乡混合发展,侵占的土地类型主要为裸地,其次为植被;2）2002-2007年城市建成区主要沿交通干道以及在市中心周边进行轴线式蔓延,2007-2012年主要在交通干道间及城市边缘地区进行填充式蔓延,城市空间形态由指状向团块状演变;3）城市蔓延方向性明显,向西北、西、西南和东南扩展较多,东南方向成为新的扩展热点,且表现出明显的距离衰减特征;4）城市蔓延主要受到人口与经济增长、交通条件改善、政策变化及土地制度缺陷等因素的影响,其中交通设施起到重要的空间引导作用。     

Finite element modelling and experimental study of oblique soccer ball bounce

In this study, we develop a finite element model to examine the oblique soccer ball bounce. A careful simulation of the interaction between the ball membrane and air pressure in the ball makes the model more realistic than analytical models, and helps us to conduct an accurate study on the effect of different parameters on a bouncing ball. This finite element model includes a surface-based fluid cavity to model the mechanical response between the ball carcass and the internal air of the ball. An experimental set-up was devised to study the bounce of the ball in game-relevant impact conditions. Ball speed, angle, and spin were measured before and after the bounce, as well as ball deformation and the forces during the impact. The finite element model has been validated with three different sets of data, and the results demonstrate that the finite element model reported here is a valuable tool for the study of ball bounce. After validation of the model, the effect of the friction coefficient on soccer ball bounce was studied numerically. Simulation results show that increasing the friction coefficient may result in reversal of the horizontal impact force.     

Differential item functioning analysis of the 2003-04 NHANES physical activity questionnaire

Using differential item functioning (DIF) analyses, this study examined whether there were any DF items in the National Health and Nutrition Examination Survey (NHANES) physical activity (PA) questionnaire. A subset of adult data from the 2003-04 NHANES study (n = 3,083) was used. PA items related to respondents' occupational, transportation, domestic, leisure-time, strength-related, and sedentary activities were analyzed for DIF using Mantel-Haenszel, SIBTEST, and analysis of variance procedures. Some items were identified as DF items, with the majority of those items favoring advantaged social groups. For example, items about domestic activity and moderate-intensity leisure-time activity were DF items favoring non-Hispanic Whites, and persons with higher levels of education (e.g., some college or more) or income (e.g, annual family income [AFI] > $34,999). The vigorous activity item was a DIF item favoring younger adults (ages 20-59 years) and persons with higher levels of education or income. Occupational PA presented DF favoring Hispanics and persons with lower levels of education (e.g., high school or less), and the transportation-related PA item presented DF favoring persons with lower incomes (e.g., AFI $34,999). These findings highlight the importance of conducting DF analysis in PA survey construction and emphasize the need to introduce DIF concepts and methods to PA researchers.     

Fundamental movement skill performance of preschool children in relation to family context

Evidence suggests the development of fundamental movement skill (FMS) is a key factor in promoting long-term physical activity. Low levels of activity among preschool children and the relationship between physical activity and the development of fundamental movement skills underline the need to determine the factors associated with children's development of such skills. As parents play an important role in the socialization process, the aim of this study was to examine correlates of family and neighbourhood characteristics as well as parental behaviour and beliefs on FMS performance in 4- to 6-year-old preschool children. Relationships between preschool children's FMS performance and family contextual variables were examined within a sample of 846 preschool children. Results identified positive associations of FMS performance with parental education, father's physical activity, transport to school by bicycle, and the high value placed by parents high on sport-specific aspects of children's physical activity. Variables negatively associated with preschool children's FMS performance included father-child interaction in TV-viewing and reading books, the high importance placed by parents on winning and performance in children's physical activity. Furthermore, the ambiguity of associations between FMS performance and parental beliefs underlined its complexity.     

加拿大城市原住民教育所面临的问题

原住民是加拿大人口增长最快的少数民族。而且正经历着大规模由农村移民到城市的过程,这一过程是其他民族都必须经历的。然而加拿大原住民在正规教育和教育机会方面还落后于整个国家的水准。造成这种现实的原因是复杂的,涉及历史关系、政府政策、变化的形势以及社会经济挑战等因素。本文力图阐述存在的问题并分析其对原住民教育机会的限制,同时对克服原住民教育机会不平等的具体措施进行了探讨。     

班级讨论会及其实践

W·格拿塞先生倡导并经多年实践的班级讨论会,已经取得了令人信服的成果,且为越来越多的教师所掌握。实践表明,班级讨论会是一种行之有效的教育措施,不论是对干解决学校普遍存在的纪律问题,还是启迪学生智慧和塑造健康心理与人格,都有积极意义。鉴于此,特将本文推荐给有志于教育改革的朋友们。     

生死大逃杀美剧《越狱》第二季劲爆开播

《越狱》回来了,Seasoon2终于重回屏幕。《越狱》称得上去年最成功的剧集之一,更创下了北美电视淡季七年来最高的周一收视纪录。今年第二季一开始,故事情节便悬念依然迭起,一场生死大逃杀又要开始了。