Editor's Special Invited Paper: Second-Guessing Clinical Trial Designs

Abstract

Modern change-point detection had its origins about 50 years ago in the work of Page, Shiryaev, and Lorden, who focused on sequential detection of a change-point in a sequence of observations. Motivation often arose from sequential quality control: to detect a disruption in the quality of a continuous production process. More recently, motivation from a broad range of applications has led to a variety of different problem formulations. In this article I will review this history with particular attention to a selected subset of applications arising in biology and to common features of different likelihood-based formulations.     

Chemical response of lakes in the Adirondack Region of New York to declines in acidic deposition

Long-term changes in the chemistry of wet deposition and lake water were investigated in the Adirondack Region of New York. Marked decreases in concentrations of SO4(2-) and H+ in wet deposition have occurred at two sites since the late 1970s. These decreases are consistent with long-term declines in emissions of sulfur dioxide (SO2) in the eastern United States. Changes in wet NO3- deposition and nitrogen oxides (NOx) emissions have been minor over the same interval. Virtually all Adirondack Lakes have shown marked decreases in concentrations of SO4(2-), which coincide with decreases in atmospheric S deposition. Concentrations of NO3- have also decreased in several Adirondack lakes. As atmospheric N deposition has not changed over this period, the mechanism contributing to this apparent increase in lake/watershed N retention is not evident. Decreases in concentrations of SO4(2-) + NO3- have resulted in increases in acid-neutralizing capacity (ANC) and pH and resulted in a shift in the speciation of monomeric Al from toxic inorganic species toward less toxic organic forms in some lakes. Nevertheless, many lakes continue to exhibit pH values and concentrations of inorganic monomeric Al that are critical to aquatic biota. Extrapolation of rates of ANC increase suggests that the time frame of chemical recovery of Adirondack Lakes will be several decades if current decreases in acidic deposition are maintained.     

From the editor.

In an attempt to make Rehabilitation Psychology an interactive forum, two new sections appear in this issue. The first is the "Readers' Forum," designed to present a submission that has successfully undergone the journal's anonymous review process and that addresses a significant rehabilitation issue. The second section, "Letters to the Editor," is designed to present feedback from readers, brief responses to and comments about previously published materials, and other information determined to be of potential interest to readers but that does not lend itself to more formal presentation. Every effort will continue to be made to make Rehabilitation Psychology responsive to its readers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How upstream collocation works

The smoothing effects of upstream collocation in convective problems are attributable to a dissipative error term analogous to that in upstream-weighted finite differences.     

Analysis of the steam injection at the Visalia Superfund Project with fully compositional nonisothermal finite difference simulations

By injecting steam, over 1.1 million pounds of creosote has been recovered at the Visalia, California Superfund Site from an aquifer 102ft underground. In the first 6 weeks of injection 320,000lb of creosote were recovered or destroyed versus <1lb per day in a pump and treat. The finite difference simulator STARS1, which is widely used in the oil industry to model thermal recovery, has been used to simulate simplified models of the project, to analyze recovery mechanisms, and to demonstrate how the operation of similar projects can be improved.The simulations indicate that vaporization of dense, nonaqueous, phase liquids (DNAPLs) is the most important recovery mechanism, that liquid production is enhanced because a gas phase is present, and that the project could have been completed more rapidly if an additional injector or producer had been added in the center of the site. In addition, the mineralization (conversion to carbon dioxide) of DNAPLs could result from reaction with water, injected air or, most likely, both. The mechanisms are likely to be similar to subcritical water oxidation.While this analysis suggests methods to improve operation of future steam projects, Visalia has been a very successful demonstration of the potential of steam injection to clean up recalcitrant hydrocarbons and will be an inspiration for future projects.     

Perception of out-group homogeneity and levels of social categorization: Memory for the subordinate attributes of in-group and out-group members.

Explored the hypothesis that in-group members perceive their own group as more variegated and complex than do out-group members (the out-group homogeneity principle). In Exps I and II, 168 men and 171 women estimated the proportion of men or women who would endorse a variety of personality/attitude items that varied on stereotypic meaning (masculinity–femininity) and social desirability (favorable–unfavorable). It was predicted and found that out-group members viewed a group as endorsing more stereotypic and fewer counterstereotypic items than did in-group members. Findings are interpreted as support for the out-group homogeneity principle, and it is argued that since this effect was general across items varying in social desirability, the phenomenon was independent of traditional ethnocentrism effects. Exp III asked 90 members of 3 campus sororities to judge the degree of intragroup similarity for their own and 2 other groups. Again, each group judged its own members to be more dissimilar to one another than did out-group judges. In Exp IV, a theory was proposed suggesting that different "levels of social categorization" are used to encode in- and out-group members' behavior and that this process could account for the perception of out-group homogeneity. It was predicted and found that 109 men and 131 women were more likely to remember the subordinate attributes of an in- than out-group member, which provides some evidence for the theoretical model. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The mechanism of cobalt drier action

The influence of cobalt driers on the initial stages of the drying of polyunsaturated esters has been studied. Cobalt (II) appears to from an unstable complex of variable composition with the polyunsaturated ester. This complex catalyzes the uptake of oxygen and increases the rate of oxygen absorption by the ester. The energy of activation for oxygen uptake by the ester in the presence of cobalt is only 1.3 kcal/mole, while in the absence of cobalt, the activation energy is 10.8 kcal/mole. The absorption of oxygen by the ester is followed by the formation of hydroxy and/or hydroperoxy groups, the loss of alkene groups, an increase in conjugation and conversion from the cis to the trans isomer. Polymerization occurs during these latter changes. Formerly Nuodex Division, Heyden Newport Chemical Corporation.     

Electromyographic patterns associated with nonnutritive sucking in 11–13-day-old rat pups.

Three experiments used an EMG technique to measure the frequency, duration, and intensity of nonnutritive sucking (NNS) in 56 11–13 day old Wistar pups. Ss were separated from their mothers for 2–6 or 20–24 hrs and then allowed to suckle an anesthetized dam for up to 3 hrs without receiving any milk. Jaw-muscle EMG and nipple detachments were recorded. EMG patterns representing 2 discrete modes of sucking were reliably discerned, as were changes in overall intensity of EMG. 20–24 hr separated Ss engaged in more frequent NNS bouts and bouts of longer duration than 2–6 hr separated Ss. Ss separated by 20–24 hrs also engaged in a mode of NNS not seen in 2–6 hr separated Ss. Overall EMG intensity was higher and frequency of nipple detachments was lower in Ss separated for 20–24 hrs. In both groups, but particularly the 20–24 hr Ss, frequency of some NNS patterns decreased as the length of the "dry" suckling increased. EMG intensity also decreased over time in both groups, and frequency of nipple detachments increased in 2–6 hr separated Ss. Data indicate that some aspects of NNS are highly labile and respond to variations of both deprivation from the mother and nutritive deprivation. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Letters from Wundt's doctoral students.

Presents letters written by 2 of Wilhelm Wundt's doctoral students, A. Berliner and B. Berliner, regarding the students' careers and graduate work with Wundt. (PsycINFO Database Record (c) 2010 APA, all rights reserved)