Are Letter Detection and Proofreading Tasks Equivalent?

When readers search for misspellings in a proofreading task or for a letter in a letter detection task, they are more likely to omit function words than content words. However, with misspelled words, previous findings for the letter detection task were mixed. In two experiments, the authors tested the functional equivalence of both tasks. Results reveal similar patterns of omissions for both search tasks when misspellings were produced by substituting one letter for another: There were more omissions for function words than for content words. However, when two letters were transposed, differences between the two tasks emerged. It is possible to conclude that letter detection and proofreading are based on common cognitive processes but the nature of the target can modulate the effects. Results are interpreted in light of the attentional disengagement model and the guidance organization model of the missing-letter effect.     

Incorporating Uncertainty Into Parallel Analysis for Choosing the Number of Factors via Bayesian Methods

A number of psychometricians have suggested that parallel analysis (PA) tends to yield more accurate results in determining the number of factors in comparison with other statistical methods. Nevertheless, all too often PA can suggest an incorrect number of factors, particularly in statistically unfavorable conditions (e.g., small sample sizes and low factor loadings). Because of this, researchers have recommended using multiple methods to make judgments about the number of factors to extract. Implicit in this recommendation is that, when the number of factors is chosen based on PA, uncertainty nevertheless exists. We propose a Bayesian parallel analysis (B-PA) method to incorporate the uncertainty with decisions about the number of factors. B-PA yields a probability distribution for the various possible numbers of factors. We implement and compare B-PA with a frequentist approach, revised parallel analysis (R-PA), in the contexts of real and simulated data. Results show that B-PA provides relevant information regarding the uncertainty in determining the number of factors, particularly under conditions with small sample sizes, low factor loadings, and less distinguishable factors. Even if the indicated number of factors with the highest probability is incorrect, B-PA can show a sizable probability of retaining the correct number of factors. Interestingly, when the mode of the distribution of the probabilities associated with different numbers of factors was treated as the number of factors to retain, B-PA was somewhat more accurate than R-PA in a majority of the conditions.     

Penguin Promises: encouraging aquarium visitors to take conservation action

This study investigates the impact of an innovative conservation action campaign called Penguin Promises implemented at uShaka Sea World in Durban, South Africa. Communication tools included interpretive signage, exhibits with and without animals, presentations, and personal interactions, along with a specially designed postcard, on which visitors could write a promise (pledge) to make a change in their daily lives to become more environmentally responsible. Visitors who completed a card were contacted a year or more after their visit and asked about the outcomes of their promise. The results (N = 316) showed that 49.4% of respondents could give an example of something positive they had done for the environment, that they attributed to the campaign. Based on the study, recommendations are provided for the design of effective visitor conservation action campaigns.     

Amplitude-modulated sinusoidal microchannels for observing adaptability in C. elegans locomotion

In this paper, we present a movement-based assay to observe adaptability in Caenorhabditis elegans locomotion behavior. The assay comprises a series of sinusoidal microchannels with a fixed wavelength and modulating (increasing or decreasing) amplitude. The channel width is comparable to the body diameter of the organism. Worms are allowed to enter the channel from the input port and migrate toward the output port. Within channel sections that closely match the worm's natural undulations, the worm movement is relatively quick and steady. As the channel amplitude increases or decreases along the device, the worm faces difficulty in generating the propulsive thrust, begins to slow down and eventually fails to move forward. A set of locomotion parameters (i.e., average forward velocity, number and duration of stops, range of contact angle, and cut-off region) is defined for worm locomotion in modulated sinusoidal channels and extracted from the recorded videos. The device is tested on wild-type C. elegans (N2) and two mutants (lev-8 and unc-38). We anticipate this passive, movement-based assay can be used to screen nematodes showing difference in locomotion phenotype.     

A large-scale donor attempt to improve educational status of the poor and household income distribution: The experience of PEDC in Vietnam

In 2003, donors combined together in Vietnam to support the provision of quality primary schooling for 226 disadvantaged districts (about a third of the country). US$160 million was invested in infrastructure, materials and training across the 226 districts. The programme has been commended by donors and received good press inside Vietnam. Comparison of achievement surveys in 2001 and 2007 showed, however, that there had been a decline in performance in the targeted districts. This article explores various hypotheses as to how this could have happened; and in particular the increasing amounts spent by better-off households on their children's education.     

陌生的父亲

这位海军陆战队员赶到医院时,期盼儿子归来的垂危老人已神智不清。为了给予老人最温暖的临终关怀,海军陆战队员寸步不离地陪伴着老人度过了漫长而安详的一夜。可是,送走老人后他却问护士:"那个男人是谁?"     

Projectile motion with quadratic damping in a constant gravitational field

The motion of a projectile in a constant gravitational field is an age-old problem. If there is no resistive force, the problem is simple. However, with the intoduction of resistive forces, the complexity of the problem increases. Recently, there has been a growing interest in the problem of projectile motion under a resistive force proportional to the square of velocity. The problem for resistive force proportional to vv cannot be solved in closed analytical form. A series solution of the equation leads to divergent series for x (t) and y (t) for reasonable values of the initial speed and angle of projection. However, we demonstrate that by inverting the series for x (t), i.e., expressing t in terms of x, and substituting this in y (t) one can express y in terms of x which is a highly convergent series and one can obtain the path of projectile with a few terms of the series. We further demonstrate that one can obtain the path even with a few terms of the divergent series for x (t) and y (t) by using extrapolation methods.     

Assessing Model Similarity in Structural Equation Modeling

Two models can be nonequivalent, but fit very similarly across a wide range of data sets. These near-equivalent models, like equivalent models, should be considered rival explanations for results of a study if they represent plausible explanations for the phenomenon of interest. Prior to conducting a study, researchers should evaluate plausible models that are alternatives to those hypothesized to evaluate whether they are near-equivalent or equivalent and, in so doing, address the adequacy of the study’s methodology. To assess the extent to which alternative models for a study are empirically distinguishable, we propose 5 indexes that quantify the degree of similarity in fit between 2 models across a specified universe of data sets. These indexes compare either the maximum likelihood fit function values or the residual covariance matrices of models. Illustrations are provided to support interpretations of these similarity indexes.