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。     

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").     

Teaching students how to study: a workshop on information processing and self-testing helps students learn

We implemented a "how to study" workshop for small groups of students (6-12) for N = 93 consenting students, randomly assigned from a large introductory biology class. The goal of this workshop was to teach students self-regulating techniques with visualization-based exercises as a foundation for learning and critical thinking in two areas: information processing and self-testing. During the workshop, students worked individually or in groups and received immediate feedback on their progress. Here, we describe two individual workshop exercises, report their immediate results, describe students' reactions (based on the workshop instructors' experience and student feedback), and report student performance on workshop-related questions on the final exam. Students rated the workshop activities highly and performed significantly better on workshop-related final exam questions than the control groups. This was the case for both lower- and higher-order thinking questions. Student achievement (i.e., grade point average) was significantly correlated with overall final exam performance but not with workshop outcomes. This long-term (10 wk) retention of a self-testing effect across question levels and student achievement is a promising endorsement for future large-scale implementation and further evaluation of this "how to study" workshop as a study support for introductory biology (and other science) students.     

Avoidance of interspecific mating in female Syrian hamsters is stronger toward familiar than toward unfamiliar heterospecific males

Adult Syrian hamster females (Mesocricetus auratus) learn to discriminate against familiar heterospecific males (Turkish hamster, M. brandti). We investigated whether females learn to avoid any heterospecific male after exposure to just one heterospecific male. We predicted that, after being exposed to one heterospecific male, a female would avoid mating not only with that familiar male but also with any unfamiliar heterospecific male. We exposed females to a heterospecific male across a wire-mesh barrier for 8 days and then paired the female with (a) that same heterospecific male or (b) an unfamiliar heterospecific male. Females exhibited lordosis faster and for a longer duration toward the unfamiliar than toward the familiar heterospecific male. However, females were similarly aggressive toward familiar and unfamiliar heterospecific males. Perhaps exposure to stimuli from several heterospecific males (a likely scenario in the wild) would result in females behaving similarly toward familiar and unfamiliar heterospecific males.     

Neighborhood poverty and early transition to sexual activity in young adolescents: a developmental ecological approach

This study examined how the link between neighborhood poverty and the timing of sexual initiation varies as a function of age, gender, and background characteristics. A sample of N = 2,596 predominately White Canadian adolescents from the National Longitudinal Survey of Children and Youth was used. Sexual initiations occurring between 12 and 15 years old were considered. Results showed that younger adolescent females who lived in poor neighborhoods and who had a history of conduct problems were more likely to report early sexual activity. Peer characteristics partly accounted for this susceptibility. Among adolescent males, no direct neighborhood effects were found, but those who had combined risks at multiple levels appeared more vulnerable. The theoretical and practical implications of these findings are discussed.     

Obstetrical complications and violent delinquency: testing two developmental pathways

This study focused on the interaction between specific obstetrical complications and early family adversity in predicting violent behavior during childhood and adolescence, in a sample of 849 boys from low socioeconomic areas of Montreal, Canada. Obstetrical complication data from medical records were used to create three scales using a nonlinear principal component analysis followed by rotation. Family adversity and teacher-rated physical aggression were assessed when the boys were in kindergarten and self-reports of delinquency were collected when they were 17. Elevated scores on the Deadly Risk Situation scale of obstetrical complications (preeclampsia, umbilical cord prolapse, and induced labor) increased the risk of being violent at both 6 and 17 years of age, only among boys who grew up in high adverse familial environments. Moreover, this interaction partly accounted for the continuity between violence in childhood and adolescence. Interventions for young pregnant women from deprived environments and their babies are discussed in light of these results.     

From farm and family to career naturalist: the apprenticeship of Vernon Bailey

How are scientists made? How, as young adults, have they discovered a scientific vocation and career? Through formal schooling, typically; but in the field sciences also through practical apprenticeship--through work. This essay presents the story of a frontier farm lad who became a career naturalist as a hired collector of animal specimens in the American West. Family and work are the leitmotifs of Vernon Bailey's story. It was family farming--bringing in the hay and finding the cows--that connected Bailey's love of skilled outdoor work with a desire to know nature scientifically. Traveling and working with professional naturalists, he came to see himself as a professional as well. His socialization was less a replacement than a layering of two identities, family and career.