探测地外引力

每个星期天的早上，我都要沿着世界上最灵敏的重力计走上长两公里的一段路。太阳和月球作用于我的身体的引力仅相当于地球引力的百万分之几，然而这样微小的力作用于太平洋上却能推动海平面升高，掀起阵阵波涛拍打我散步时走过的路径。但是在实验室内分离出这些微弱的力即使对专业仪器来说也是一件艰难的任务。     

游动的智能代理人

以蚂蚁和其它群居性昆虫为模型，计算机科学家开发了互相合作以解决复杂问题——例如在繁忙的通信网络中重新安排通信源——的软件代理人。     

当天空不是极限时

智利诗人聂鲁达用一句话概括了他的命运观，即“每次偶然的际遇都是早有安排”。而天体物理学家Neil deGrasse Tyson的观点与之类似，无论是他在思索银河系的演变过程还是在思索个人的人生经历时都持这样的观点。41岁的Tyson的人生际遇把他推到了现在的职位上——美国自然史博物馆海登天文馆(于今年2月重新开放)的罗斯馆长一职。     

Increasing public understanding of transgenic crops through the World Wide Web

Transgenic crops among the most controversial "science and society" issues of recent years. Because of the complex techniques involved in creating these crops and the polarized debate over their risks and beliefs, a critical need has arisen for accessible and balanced information on this technology. World Wide Web sites offer several advantages for disseminating information on a fast-changing technical topic, including their global accessibility; and their ability to update information frequently, incorporate multimedia formats, and link to networks of other sites. An alliance between two complementary web sites at Colorado State University and the University of Nebraska-Lincoln takes advantage of the web environment to help fill the need for public information on crop genetic engineering. This article describes the objectives and features of each site. Viewership data and other feedback have shown these web sites to be effective means of reaching public audiences on a complex scientific topic.     

温顺的野蛮人

加州大学洛杉矶分校的Jared Diamond曾把人类列为"第三种黑猩猩"(第二种是倭黑猩猩).从基因上说,人类与黑猩猩的确非常相近;而且,两个不同群体的黑猩猩彼此间敌意甚深,非常喜欢打斗,在这一点上与人类如出一辙(参看上期本专栏"无知的野蛮人").     

Implementation of a project-based molecular biology laboratory emphasizing protein structure-function relationships in a large introductory biology laboratory course

In introductory laboratory courses, many universities are turning from traditional laboratories with predictable outcomes to inquiry-inspired, project-based laboratory curricula. In these labs, students are allowed to design at least some portion of their own experiment and interpret new, undiscovered data. We have redesigned the introductory biology laboratory course at Brandeis University into a semester-long project-based laboratory that emphasizes concepts and contains an element of scientific inquiry. In this laboratory, students perform a site-directed mutagenesis experiment on the gene encoding human γD crystallin, a human eye lens protein implicated in cataracts, and assess the stability of their newly created protein with respect to wild-type crystallin. This laboratory utilizes basic techniques in molecular biology to emphasize the importance of connections between DNA and protein. This project lab has helped engage students in their own learning, has improved students' skills in critical thinking and analysis, and has promoted interest in basic research in biology.     

Pregnant students in the gross anatomy laboratory: policies and practices at chiropractic colleges

Chiropractic and medical colleges have experienced a significant increase in the number of female applicants in recent years, a percentage of whom are pregnant or become pregnant following admission. It is therefore important to ask the question: How do institutions that educate future health care providers address the issue of pregnancy and the gross anatomy laboratory? A survey instrument was developed and pretested. IRB approval was obtained. The administrators charged with overseeing the policies and practices for the gross anatomy laboratory at each of the 16 chiropractic colleges in the USA were identified and contacted. An email containing a link to the Web based survey was sent to each, using SurveyMonkey. The survey response rate was 100%. A majority of colleges (69%) have a written policy regarding pregnancy and the gross laboratory. Of these, 36% allow pregnant students to take the laboratory if a waiver is signed, 18% do not allow them to take the laboratory, 18% allow them to take it without a waiver, and 27% have other policies. In cases where students do not take the gross laboratory while pregnant, 64% of colleges require them to take the laboratory after completion of their pregnancy, 27% require them to complete an alternative (dry) laboratory, and 9% have other policies. Considerable diversity exists in the way colleges address this issue. It is at present unknown whether pregnant students or their fetuses are at any risk from laboratory chemicals. Risk assessment research is needed before consistent policies can be developed. Anat Sci Educ. © 2011 American Association of Anatomists.     

Childhood abuse and later parenting outcomes in two American Indian tribes

OBJECTIVES: To examine the relationship of childhood physical and sexual abuse with reported parenting satisfaction and parenting role impairment later in life among American Indians (AIs). METHODS: AIs from Southwest and Northern Plains tribes who participated in a large-scale community-based study (n=3,084) were asked about traumatic events and family history; those with children were asked questions about their parenting experiences. Regression models estimated the relationships between childhood abuse and parenting satisfaction or parenting role impairment, and tested for mediation by depression or substance use disorders. RESULTS: Lifetime substance use disorder fully mediated the relationship between childhood physical abuse and both parenting satisfaction and parenting role impairment in the Northern Plains tribe. There was only partial mediation between childhood sexual abuse and parenting role impairment in the Southwest. In both tribes, lifetime depression did not meet the criteria for mediation of the relationship between childhood abuse and the two parenting outcomes. Instrumental and perceived social support significantly enhanced parenting satisfaction; negative social support reduced satisfaction and increased the likelihood of parenting role impairment. Exposure to parental violence while growing up had deleterious effects on parenting outcomes. Mothers and fathers did not differ significantly in the relation of childhood abuse experience and later parenting outcomes. CONCLUSIONS: Strong effects of social support and mediation of substance abuse disorders in the Northern Plains offer direct ways in which childhood victims of abuse could be helped to avoid negative attributes of parenting that could put their own children at risk. PRACTICE IMPLICATIONS: Mothers were not significantly different from fathers in the relation of abusive childhood experiences and later parenting outcomes, indicating both are candidates for interventions. Strong effects of social support offer avenues for interventions to parents. The prevalence of substance use disorders and their role as a mediator of two parenting outcomes in the Northern Plains should focus special attention on substance use treatment, especially among those who experienced childhood victimization. These factors offer direct ways in which childhood victims of abuse can be helped to avoid negative attributes of parenting that could put their own children at risk of violence.     

The influence of racial socialization practices on the cognitive and behavioral competence of African American preschoolers

The association between parent racial socialization and child competence was examined in a socioeconomically diverse sample of African American preschoolers living in an urban setting. Interviews were conducted in the homes of 200 families. Racial socialization was assessed by parent report as well as by observation of the sociocultural context of the home, and child outcomes were assessed using the Kaufman Assessment Battery for Children and the Child Behavior Checklist. Results indicated that African American parents who provided homes that were rich in African American culture had preschool children who had greater amounts of factual knowledge and better developed problem-solving skills. African American parents who socialized their preschool children to be proud of their heritage reported fewer problem behaviors.     

Randomized trial of a statewide home visiting program: impact in preventing child abuse and neglect

OBJECTIVES: To assess the impact of home visiting in preventing child abuse and neglect in the first 3 years of life in families identified as at-risk of child abuse through population-based screening at the child's birth. METHODS: This experimental study focused on Hawaii Healthy Start Program (HSP) sites operated by three community-based agencies. From 11/94 to 12/95, 643 families were enrolled and randomly assigned to intervention and control groups. Child abuse and neglect were measured by observed and self-reported parenting behaviors, all hospitalizations for trauma and for conditions where hospitalization might have been avoided with adequate preventive care, maternal relinquishment of her role as primary caregiver, and substantiated CPS reports. Data were collected through annual maternal interviews (88% follow-up each year of all families with baseline interviews); observation of the home environment; and review of CPS, HSP, and pediatric medical records. RESULTS: HSP records rarely noted home visitor concern about possible abuse. The HSP and control groups were similar on most measures of maltreatment. HSP group mothers were less likely to use common corporal/verbal punishment (AOR=.59, p=.01) but this was attributable to one agency's reduction in threatening to spank the child. HSP group mothers reported less neglectful behavior (AOR=.72, .02), related to a trend toward decreased maternal preoccupation with problems and to improved access to medical care for intervention families at one agency. CONCLUSIONS: The program did not prevent child abuse or promote use of nonviolent discipline; it had a modest impact in preventing neglect. Possible targets for improved effectiveness include the program's implementation system and model.