Beyond "The limits to peat bog growth'': Cross-scale feedback in peatland development

Copyright by the Ecological Society of America 2006, for personal or educational use only. Article is available at <http://dx.doi.org/10.1890/0012-9615(2006)076[0299:BTLTPB]2.0.CO;2

Centrality in children's best friend networks: the role of social behaviour

Centrality is an indicator of an individual's relative importance within a social group. Predictors of centrality in best friendship networks were examined in 146 children (70 boys, 76 girls, Mage= 9.95). Children completed measures of social confidence, social desirability, friendship quality, school liking, and loneliness, and nominated their best friends from within their class at two time points, 3 months apart. Multigroup path analysis revealed gender differences in the antecedents of centrality. Social confidence, social desirability, and friendship quality predicted changes in the indicators of centrality in best friend networks over time. In boys’ social behaviour positively predicted changes in centrality whereas in girls’ social behaviour negatively predicted changes in centrality. Together, these findings suggest that some aspects of social behaviour are influential for centrality in best friend groups

Heterogeneity of gene expression of the hemagglutinin-esterase (HE) protein of murine coronaviruses.

The hemagglutinin-esterase (HE) membrane glycoprotein is present only in some members of the coronavirus family, including some strains of mouse hepatitis virus (MHV). In the JHM strain of MHV, expression of the HE gene is variable and corresponds to the number of copies of a UCUAA pentanucleotide sequence present at the 3'-end of the leader RNA. This copy number varies among MHV strains, depending on their passage history. The JHM isolates with two copies of UCUAA in their leader RNA showed a high level of HE expression, whereas the JHM isolate with three copies had a low-level expression. In this study, the analysis of HE gene expression was extended to other MHV strains. The synthesis of HE mRNA in these viruses also correlates with the copy number of UCUAA in the leader RNA and the particular intergenic sequence preceding the HE gene. In one MHV strain, MHV-1, no detectable HE mRNA was synthesized, despite the presence of a proper transcription initiation signal. This lack of HE mRNA expression was consistent with a leader RNA containing three UCUAA copies. However, mutations and deletions within the coding region of the MHV-1 HE gene have generated a stretch of sequence which resembled the transcriptional initiation motif, and was shown to initiate the synthesis of a novel smaller mRNA. These findings strengthened the theory that interactions between leader RNA and transcriptional initiation sequences regulate MHV subgenomic mRNA transcription. Sequence analysis revealed that most MHV strains, through extensive mutations, deletions, or insertions, have lost the complete HE open reading frame, thus turning HE into a pseudogene. This high degree of variation is unusual as the other three structural proteins (spike, membrane, and nucleocapsid) are well-maintained. In contrast to bovine coronavirus, which apparently requires HE for viral replication, the HE protein in MHV may be only an accessory protein which is not necessary for viral replication. JHM and MHV-S, however, have preserved the expression of HE protein

Agreement Among Radiographs, Fluoroscopy and Bronchoscopy in Documentation of Airway Collapse in Dogs.

BackgroundAirway collapse is a common finding in dogs with chronic cough, yet the diagnosis can be difficult to confirm without specialty equipment.HypothesisBronchoscopic documentation of tracheobronchial collapse will show better agreement with fluoroscopic imaging than with standard radiography.AnimalsForty-two dogs prospectively evaluated for chronic cough.MethodsIn this prospective study, three-view thoracic radiographs were obtained followed by fluoroscopy during tidal respiration and fluoroscopy during induction of cough. Digital images were assessed for the presence or absence of collapse at the trachea and each lobar bronchus. Bronchoscopy was performed under general anesthesia for identification of tracheobronchial collapse at each lung segment. Agreement of imaging tests with bronchoscopy was evaluated along with sensitivity and specificity of imaging modalities as compared to bronchoscopy.ResultsAirway collapse was identified in 41/42 dogs via 1 or more testing modalities. Percent agreement between pairs of tests varied between 49 and 87% with poor-moderate agreement at most bronchial sites. Sensitivity for the detection of bronchoscopically identified collapse was highest for radiography at the trachea, left lobar bronchi, and the right middle bronchus, although specificity was relatively low. Detection of airway collapse was increased when fluoroscopy was performed after induction of cough compared to during tidal respiration.ConclusionsRadiography and fluoroscopy are complementary imaging techniques useful in the documentation of bronchial collapse in dogs. Confirming the presence or absence of tracheal or bronchial collapse can require multiple imaging modalities as well as bronchoscopy

Examining the components of children's peer liking as antecedents of school adjustment

Children’s social interactions with their peers influence their psychosocial adjustment; consequently, the relationship between class-wide peer liking, same-gender peer liking, and school adjustment was explored in two age groups. Peer liking was analysed using the social relations model (SRM). In Study 1, 205 children (103 female and 102 male, Mage = 7.15, SD = 7 months) completed measures of peer liking and school adjustment, and teachers completed the Short-Form TRSSA. In Study 2, 197 children (98 female and 90 male, Mage = 9.87, SD = 5.9 months) completed measures of peer liking and school adjustment. Both studies yielded evidence of reciprocal liking and individual differences in the ratings of liking awarded to, and elicited from, both peer groups. Multigroup path analysis, with groups created according to gender, revealed that elements of liking predicted different aspects of school adjustment with some variation according to age and gender. Together, these findings suggest that the SRM can be used to examine peer liking and underscore the importance of children’s peers for school adjustment

Does correction for guessing reduce students' performance on multiple-choice examinations? Yes? No? Sometimes?

Multiple-choice (MC) examinations are becoming increasingly popular in higher education because they can be used effectively to assess breadth of knowledge in large cohorts of students. This present research investigated Psychology students' performance on, and experiences of, MC examinations with and without correction for guessing. In Study 1, data were collected from two cohorts of students across three Psychology MC examinations. The results revealed that students scored higher, and left fewer questions unanswered, when there was no correction for guessing. Furthermore, when the correction for guessing was removed from the theory MC examination, students who were told there was no correction for guessing did better than those told there was a correction. In addition, there was limited evidence of gender differences, with female students performing significantly better on one MC examination than males. In Study 2, a further set of first-year Psychology students reported their experiences of correction for guessing on open-book and closed-book MC examinations. Students reported feeling less anxious and more confident on the open-book MC examination. The findings of both of these studies have implications for instructors deciding whether or not correction for guessing is appropriate, and for the advice to be given to students preparing for MC examinations