Orientation invariant pattern recognition by pigeons (Columba livia) and humans (Homo sapiens).

The orientation invariance of visual pattern recognition in pigeons and humans was studied using a conditioned matching-to-sample procedure. A rotation effect, a lengthening of choice latencies with increasing angular disparities between sample and comparison stimuli, was replicated with humans. The choice speed and accuracy of pigeons was not affected by orientation disparities. Novel mirror-image stimuli, rotation of sample shapes, a delayed display of comparison shapes, and a mixed use of original and reflected sample shapes did not lead to a rotation effect in pigeons. With arbitrarily different odd comparison shapes, neither humans nor pigeons showed a rotation effect. Final experiments supported the possibility that the complete absence of a rotation effect in pigeons is because they are relatively better than humans at discriminating mirror-image shapes compared with arbitrary shapes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceived parental social support and academic achievement: An attachment theory perspective.

[Correction Notice: An erratum for this article was reported in Vol 66(4) of Journal of Personality and Social Psychology (see record 2008-10478-001). This article, which appeared in the Personality and Individual Differences section was accepted for publication by Guest Editor Irwin Sarason. We wish to thank Professor Sarason for his help and to apologize for our oversight in not acknowledging this contribution.] Tested the extent to which parental social support predicted college GPA among undergraduates. A sample of 418 undergraduates completed the Social Provisions Scale—Parent Form (C. E. Cutrona; see record 1990-01422-001) and measures of family conflict and achievement orientation. American College Testing (ACT) Assessment Program college entrance exam scores (American College Testing Program, 1986) and GPA were obtained from the university registrar. Parental social support, especially reassurance of worth, predicted college GPA when controlling for academic aptitude (ACT scores), family achievement orientation, and family conflict. Support from parents, but not from friends or romantic partners, significantly predicted GPA. Results are interpreted in the context of adult attachment theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A mathematical model of serotype replacement in pneumococcal carriage following vaccination

A number of childhood vaccination programmes have recently introduced vaccination against Streptococcus pneumoniae, the pneumococcus, a major cause of pneumonia and meningitis. The pneumococcal conjugate vaccines (PCVs) that are currently in use only protect against some serotypes of the bacterium, and there is now strong evidence that those serotypes not included in the vaccine increase in prevalence among most vaccinated populations. We present a mathematical model for the dynamics of nasopharyngeal carriage of S. pneumoniae that allows for carriage with multiple serotypes. The model is used to predict the prevalence of vaccine type (VT) and non-VT (NVT) serotypes following the introduction of PCV. Parameter estimates for the model are obtained by maximum likelihood using pre-vaccination data from The Gambia. The model predicts that low (1, 6A and 9V) and medium (4, 5, 7F, 14, 18C, 19A and 19F) prevalence serotypes can be eliminated through vaccination, but that the overall prevalence of carriage will be reduced only slightly because of an increase in the prevalence of NVT serotypes. Serotype replacement will be sequential, with high and medium prevalence NVT serotypes dominating initially, followed by an increase of serotypes of low prevalence. We examine the impact of a hypothetical vaccine that provides partial protection against all serotypes, and find that this reduces overall carriage, but is unable to eliminate low or medium prevalence serotypes.     

On the role of conserved proline residues in the structure and function of Clostridium pasteurianum 2[4Fe-4S] ferredoxin

The widespread occurrence of Pro residues adjacent to Cys ligandsin the sequences of [4Fe-4S] electron transfer proteins hasnot yet found a functional basis. The two such Pro of Clostridiumpasteurianum 2[4Fe-4S] ferredoxin have been probed by site-directedmutagenesis. Any one of them, but not both simultaneously, canbe substituted without impairing the proper folding of the protein.The reduction potentials of the ferredoxin variants fall ina narrow range of <20 mV above the potential of the nativeprotein. The biological activities with C.pasteurianum hydrogenaseand pyruvate-ferredoxin oxidoreductase do not change significantly,except when Lys replaces Pro. In these cases, the data suggestthat the two clusters of 2[4Fe-4S] ferredoxin may not alwaysbe equivalent in the interaction with the redox partners. Destabilizationof the structure has been observed as the consequence of theProl9 or Pro48 substitutions. Using 2-D NMR, this effect hasbeen associated with perturbations of both the hydrogen bondnetwork and one amino acid side chain around the [4Fe-4S] clusters.Thus, the conserved Pro found in the binding motif of [4Fe-4S]clusters in proteins strongly stabilizes the active site butdoes not play an essential role in the mechanism of electrontransfer.