Northwestern University

About: Northwestern University is a education organization based out in Evanston, Illinois, United States. It is known for research contribution in the topics: Population & Medicine. The organization has 75430 authors who have published 188857 publications receiving 9463252 citations. The organization is also known as: Northwestern & NU.

Factors relevant to the validity of experiments in social settings.

Abstract: This chapter attempts a specification of the major categories of extraneous variables and employs these categories in evaluating the validity of standard designs for experimentation in the social sciences. The extraneous variables affecting internal validity are introduced in the process of analyzing three pre-experimental designs. In the subsequent evaluation of the applicability of three true experimental designs, factors leading to external invalidity are introduced. In analyzing the extraneous variables which experimental designs for social settings seek to control, seven categories have been distinguished: history, maturation, testing, instrument decay, regression, selection, and mortality. In general, the simple or main effects of these variables jeopardize the internal validity of the experiment and are adequately controlled in standard experimental designs. The interactive effects of these variables and of experimental arrangements affect the external validity of generalizability of experimental results. Standard experimental designs vary in their susceptibility to these interactive effects.

Utopian Enterprise: Articulating the Meanings of Star Trek’s Culture of Consumption

Abstract: In this article, I examine the cultural and subcultural construction of consumption meanings and practices as they are negotiated from mass media images and objects. Field notes and artifacts from 20 months of fieldwork at Star Trek fan clubs, at conventions, and in Internet groups, and 67 interviews with Star Trek fans are used as data. Star Trek’s subculture of consumption is found to be constructed as a powerful utopian refuge. Stigma, social situation, and the need for legitimacy shape the diverse subcultures’ consumption meanings and practices. Legitimizing articulations of Star Trek as a religion or myth underscore fans’ heavy investment of self in the text. These sacralizing articulations are used to distance the text from its superficial status as a commercial product. The findings emphasize and describe how consumption often fulfills the contemporary hunger for a conceptual space in which to construct a sense of self and what matters in life. They also reveal broader cultural tensions between the...

Power and Perspectives Not Taken

Abstract: Four experiments and a correlational study explored the relationship between power and perspective taking. In Experiment 1, participants primed with high power were more likely than those primed with low power to draw an E on their forehead in a self-oriented direction, demonstrating less of an inclination to spontaneously adopt another person's visual perspective. In Experiments 2a and 2b, high-power participants were less likely than low-power participants to take into account that other people did not possess their privileged knowledge, a result suggesting that power leads individuals to anchor too heavily on their own vantage point, insufficiently adjusting to others' perspectives. In Experiment 3, high-power participants were less accurate than control participants in determining other people's emotion expressions; these results suggest a power-induced impediment to experiencing empathy. An additional study found a negative relationship between individual difference measures of power and perspective taking. Across these studies, power was associated with a reduced tendency to comprehend how other people see, think, and feel.

Laparoscopic colectomy for cancer is not inferior to open surgery based on 5-year data from the COST Study Group trial.

Abstract: Purpose: Oncologic concerns from high wound recurrence rates prompted a multi-institutional randomized trial to test the hypothesis that disease-free and overall survival are equivalent, regardless of whether patients receive laparoscopic-assisted or open colectomy. Methods: Eight hundred seventy-two patients with curable colon cancer were randomly assigned to undergo laparoscopic-assisted or open colectomy at 1 of 48 institutions by 1 of 66 credentialed surgeons. Patients were followed for 8 years, with 5-year data on 90% of patients. The primary end point was time to recurrence, tested using a noninferiority trial design. Secondary endpoints included overall survival and disease-free survival. (Kaplan-Meier) Results: As of March 1, 2007, 170 patients have recurred and 252 have died. Patients have been followed a median of 7 years (range 5-10 years). Disease-free 5-year survival (Open 68.4%, Laparoscopic 69.2%, P = 0.94) and overall 5-year survival (Open 74.6%, Laparoscopic 76.4%, P = 0.93) are similar for the 2 groups. Overall recurrence rates were similar for the 2 groups (Open 21.8%, Laparoscopic 19.4%, P = 0.25). These recurrences were distributed similarly between the 2 treatment groups. Sites of first recurrence were distributed similarly between the treatment arms (Open: wound 0.5%, liver 5.8%, lung 4.6%, other 8.4%; Laparoscopic: wound 0.9%, liver 5.5%, lung 4.6%, other 6.1%). Conclusion: Laparoscopic colectomy for curable colon cancer is not inferior to open surgery based on long-term oncologic endpoints from a prospective randomized trial.

Stimulus onset quenches neural variability: a widespread cortical phenomenon

Abstract: Neural responses are typically characterized by computing the mean firing rate, but response variability can exist across trials. Many studies have examined the effect of a stimulus on the mean response, but few have examined the effect on response variability. We measured neural variability in 13 extracellularly recorded datasets and one intracellularly recorded dataset from seven areas spanning the four cortical lobes in monkeys and cats. In every case, stimulus onset caused a decline in neural variability. This occurred even when the stimulus produced little change in mean firing rate. The variability decline was observed in membrane potential recordings, in the spiking of individual neurons and in correlated spiking variability measured with implanted 96-electrode arrays. The variability decline was observed for all stimuli tested, regardless of whether the animal was awake, behaving or anaesthetized. This widespread variability decline suggests a rather general property of cortex, that its state is stabilized by an input.