A New Era of Minimal Effects? A Response to Bennett and Iyengar

This article takes up Bennett and Iyengar's (2008) call for debate about the future of political communication effects research. We outline 4 key criticisms. First, Bennett and Iyengar are too quick to dismiss the importance of attitude reinforcement, long recognized as an important type of political media influence. Second, the authors take too narrow a view of the sources of political information, remaining fixated on news. Third, they offer an incomplete portrayal of selective exposure, exaggerating the extent to which individuals avoid attitude-discrepant information. Finally, they lean toward determinism when describing the role technologies play in shaping our political environment. In addition, we challenge Bennett and Iyengar's assertion that only brand new theory can serve to help researchers understand today's political communication landscape. We argue that existing tools, notably the Elaboration Likelihood Model (ELM), retain much utility for examining political media effects. Contrary to Bennett and Iyengar's claims, the ELM suggests that the contemporary political information environment does not necessarily lead to minimal effects.     

Destructive testing of defective weldments: Fracture mechanics predictions of failure loads and defect criticalities compared with experimental results

Thirty welded test plates containing discrete artificial defects were tested to destruction under controlled four point bending, and the failure loads recorded. The defect parameters, length, height and depth, were measured from the resulting fracture surfaces. Prior to destructive testing, the defective welds had been ultrasonically inspected, in two separate UT programmes, by a number of independent operators. Both actual and predicted defect sizes were used in conjunction with the Design Curve approach of British Standard PD 6493 to calculate failure stresses for each of the test plates. In addition, the Failure Assessment Diagram of the Central Electricity Generating Board (UK) R-6 document was used to establish defect criticality, of both the actual and the predicted defect parameters.

The results obtained indicate that there appeared to be some tolerance in both assessment routes to the significant variability observed in the ultrasonic defect size predictions. However, precise predictions of failure stress levels and defect criticalities are only possible when defects are accurately sized.     

Multiple measures of hand-use lateralization in the ring-tailed lemur (Lemur catta).

Evaluated a free-ranging matriline of 13 ring-tailed lemurs (Lemur catta) from videotaped records for lateralized hand use with 2 tasks and 4 measures: food reaching, feeding posture, duration of food holding, and manipulation of food between mouth and hand while eating. Binomial z scores determined 7 lemurs to be left preferent in reaching, 3 right, and 3 ambipreferent. Ideographic analyses suggested possible sex-linked and early experience twin effects. When compared to right and ambipreferent lemurs, left reach preferent lemurs used the left hand more but bimanuals grasped less in food holding and also engaged in less hand-mouth food manipulation. The tendency to manipulate food was not correlated with bimanual holding but was inversely related to left hand holding and directly related to right hand holding. These patterns are discussed as possible precursors of human bimanual manipulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Knowledge, strategy, and motivational contributions to preschool children's object recall.

This study examined the contributions of four individual difference predictors to preschool children's recall for object names. Measures of object knowledge (the Peabody Picture Vocabulary Test [PPVT]), conceptual tempo (the Kansas Reflection-Impulsivity Scale for Preschoolers [KRISP] error scores), strategic study period activities, and teacher ratings of children's mastery motivation were used to predict recall scores of 3- and 4-year-old children. KRISP-error scores, strategic study activities, and motivation ratings were found to be significant correlates of recall. Motivation ratings entered a regression prediction equation first, followed by the strategic study activity measure, yielding a multiple correlation of .62. These predictors were unrelated, suggesting that motivational factors contributed to young children's recall proficiency directly, perhaps through greater task involvement and analysis and more effortful retrieval activity, and do not mediate strategic study behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The development of a coded 8 PSK modem using digital signal processors

A prototype 64 kb/s coded eight phase shift key (C8PSK) modem has been successfully developed using a combination of conventional analogue circuitry and software-based digital signal processing. The C8PSK scheme is fully compatible regarding interference criteria with existing satellite FDMA access requirements and offers more efficient use of the satellite resource than conventional quaternary PSK (QPSK) systems. The C8PSK unit may either maintain channel performance with a lower satellite power requirement or improve the user bit error rate (BER) without the need for extra satellite power or bandwidth. The prototype modem was developed in a general way so that other PSK modulation schemes could be accommodated by replacing PROM units. Software processing also allows adaptive operation which adjusts the processing technique to optimize operation for a degraded signal-to-noise environment.     

Crystal structures of a marginally active thymidylate synthase mutant, Arg 126-->Glu

Thymidylate synthase (TS) is a long-standing target for anticancer drugs and is of interest for its rich mechanistic features. The enzyme catalyzes the conversion of dUMP to dTMP using the co-enzyme methylenetetrahydrofolate, and is perhaps the best studied of enzymes that catalyze carbon-carbon bond formation. Arg 126 is found in all TSs but forms only 1 of 13 hydrogen bonds to dUMP during catalysis, and just one of seven to the phosphate group alone. Despite this, when Arg 126 of TS from Escherichia coli was changed to glutamate (R126E), the resulting protein had kcat reduced 2000-fold and Km reduced 600-fold. The crystal structure of R126E was determined under two conditions--in the absence of bound ligand (2.4 A resolution), and with dUMP and the antifolate CB3717 (2.2 A resolution). The first crystals, which did not contain dUMP despite its presence in the crystallization drop, displayed Glu 126 in a position to sterically and electrostatically interfere with binding of the dUMP phosphate. The second crystals contained both dUMP and CB3717 in the active site, but Glu 126 formed three hydrogen bonds to nearby residues (two through water) and was in a position that partially overlapped with the normal phosphate binding site, resulting in a approximately 1 A shift in the phosphate group. Interestingly, the protein displayed the typical ligand-induced conformational change, and the covalent bond to Cys 146 was present in one of the protein's two active sites.     

Colonic and anorectal function in constipated patients with anorexia nervosa

OBJECTIVES: Many patients with eating disorders complain of severe constipation. Previous studies have suggested that constipation in patients with anorexia nervosa may be associated with slow colonic transit. However, it is unclear whether a refeeding program will alter colonic transit in these patients. The aim of this study was to investigate colorectal function by measuring colonic transit and anorectal function in anorexic patients with constipation during treatment with a refeeding program. METHODS: We prospectively studied 13 female patients with anorexia nervosa who were admitted to an inpatient treatment unit and compared them to 20 previously studied, age-matched, healthy female control subjects. Patients underwent colonic transit studies using a radiopaque marker technique and anorectal manometry measuring anal sphincter function, rectal sensation, expulsion dynamics, and rectal compliance. Patients were studied both early (< 3 wk) and late (> 3 wk) in their admission. We restudied two patients who had slow colonic transit. All patients also underwent structured interviews. RESULTS: Four of six patients studied within the first 3 wk of their admission had slow colonic transit, defined as > 70 h (108.0 +/- 17.0 h, mean +/- SEM), on initial evaluation. In contrast, none of the seven patients studied later than 3 wk into their admission had slow colonic transit. Two of the four patients with slow transit were restudied later in their admission and were found to have normal transit times. Rectal sensation, internal anal sphincter relaxation threshold, rectal compliance, sphincter pressures, and expulsion pattern were normal in all subjects. CONCLUSIONS: Despite complaints of severe constipation, colonic transit is normal or returns to normal in the majority of patients with anorexia nervosa once they are consuming a balanced weight gain or weight maintenance diet for at least 3 wk.