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Biomedical subjects

Rebecca Brown

Publications and source records attributed to Rebecca Brown.

7 recordsLinked to original sources
PubMed2006

Changes in arch width. A 20-year longitudinal study of orthodontic treatment.

The changes in the dental arch dimensions that occur as a result of growth and treatment are of interest to the orthodontist and require careful consideration during treatment planning. A greater understanding of these changes could influence the patient's expectations from treatment as well as the formulation of the treatment and retention plans by the clinician. A retrospective study of the maxillary and mandibular canine and molar arch width changes in 60 patients over 20 years was carried out. Approximately half were treated orthodontically, and measurements were made on dental casts taken at four time points during the study: 1981, 1985, 1989, and 2001. Between baseline and final follow-up, the treated group demonstrated a statistically significant increase in maxillary intercanine arch width and statistically significant decreases in maxillary intermolar and mandibular intercanine and intermolar widths. No significant changes were observed for the untreated group. When comparing the orthodontically treated group with the untreated group, there was a significantly greater increase in maxillary intercanine width and a significantly greater reduction in mandibular intercanine width in the treated group over the duration of the study. No significant difference was observed between treated and untreated groups for maxillary and mandibular intermolar width changes. Sex had no statistically significant effect on these treatment differences. Type of orthodontic treatment had no effect on arch width changes within the treated group; however, the effect of tooth extraction needs further investigation.

Adolescent↗
PubMed2006

Computer-aided forensics: facial reconstruction.

The 3D reconstruction of facial features from skeletal remains is a key component to the identification of missing persons and victims of violent crime. A comprehensive Computed Tomography (CT) head-scan database is currently being collected which will enable a new approach to forensic facial reconstruction. Using this unique resource, we show how a face space can be tailored to a specific unknown, or questioned skull. A set of database derived estimates of the questioned face is constructed by first computing non-rigid transformations between the known head-scan skulls and the questioned skull followed by application of these transformations to the known head-scan faces. This effectively factors out influences due to skeletal variation. A tailored face space is formed by applying Principal Component Analysis (PCA) to this ensemble of estimates of the questioned face. Thus, the face space is a direct approximation of correlated soft tissue variance indicative of the population. Ours is the first mathematical representation of the face continuum associated with a given skull. Embedded in this space resides the elements needed for recognition.

Computer-Aided Design↗
PubMed2005

A cultural comparison of treatment need.

The aims of this study were two-fold. First to compare the perceptions of African dental aesthetics as determined by a panel of black African Senegalese and French Caucasian judges, and second to compare the sensitivity and specificity of both components of the Index of Orthodontic Treatment Need (IOTN) and the Index of Complexity, Outcome and Need (ICON) in relation to the opinions of African and Caucasian judges. Ninety-eight colour digital dental images of black adolescents and adults were scored for attractiveness on a 100 mm visual analogue scale (VAS) by 45 Caucasian and 41 black African judges. In addition the judges were asked to classify the level of treatment need. Both components of the IOTN and ICON were recorded for the 98 cases. The results indicated that Caucasian judges perceived the majority of images to be less attractive than African judges. African and Caucasian judges showed similar levels in the estimation of treatment need. The aesthetic component (AC) of the IOTN and ICON showed similar levels of sensitivity. Taking all factors into account, it would appear that the ICON is marginally better at identifying those individuals who are perceived to need orthodontic treatment.

Adolescent↗
PubMed2005

An update on the analysis of agreement for orthodontic indices.

The training of clinicians in the correct use of commonly used orthodontic indices involves calibration. The level of agreement between the trainee and a standard is assessed both as a measure of reproducibility and the success of training programmes. For the Peer Assessment Rating (PAR) index and the Index of Complexity, Outcome and Need (ICON), the recommended level of acceptable inter-rater agreement is no more than +/-12 and +/-18, respectively. Many commonly used methods of analysing this type of agreement are inappropriate. The method used in this investigation allows the calculation of limits of agreement, which easily demonstrate any major departures in agreement between trainee scores and standard scores. The basic method assumes that the differences between trainee and standard scores are normally distributed and that there is no relationship between these differences and the magnitude of the index. An extension to this approach is required when the assumptions of the basic method are not upheld. This extension provides a regression-based approach to calculating limits of agreement. The results of this study demonstrate that the assumptions of the basic approach need to be checked for each comparison of trainee versus standard. In addition, regression-based methods are a more accurate means of calculating limits of agreement when these assumptions are not upheld. They also provide more information about bias and the range of disagreement between raters.

Algorithms↗
PubMed2004

Comanagement of wildlife corridors: the case for citizen participation in the Algonquin to Adirondack proposal.

The debate between top-down and bottom-up planning has recently re-emerged in environmental management. Many commentators agree on the merits of comanagement, in which affected citizens and professional managers share responsibility for planning. Nevertheless, the manifold advantages of comanagement have not always been fully appreciated in environmental planning. For example, a group representing NGOs and academic institutions recently proposed an ecological corridor linking Algonquin Provincial Park in southern Ontario to the Adirondack Park in northern New York. This corridor, known as A2A, was designed to encourage the migration of wolves and other wildlife between the parks. Much of the land in A2A is private property. A survey of households, randomly scattered throughout the United States portion of the corridor, revealed that affected landowners had little knowledge of the proposal and no contact with its advocates. Many respondents were farmers who utilized land for livelihood. Other landowners enjoyed property for a variety of recreational purposes. Regardless of use, survey participants placed high value on the importance of conserving biological diversity. They also expressed great distrust toward restrictions that might be placed on their activities. In general, respondents felt very unsure about A2A, and they were uncertain about personal involvement in the planning process. Certain landowners indicated a willingness to have their land be included in an ecological corridor, despite not knowing about it before the survey was administered. These results suggest that A2A proponents have little to lose and much to gain by disseminating information locally and by embracing comanagement for further formulation of this plan.

Animals↗
PubMed2003

NPR1 modulates cross-talk between salicylate- and jasmonate-dependent defense pathways through a novel function in the cytosol.

Plant defenses against pathogens and insects are regulated differentially by cross-communicating signal transduction pathways in which salicylic acid (SA) and jasmonic acid (JA) play key roles. In this study, we investigated the molecular mechanism of the antagonistic effect of SA on JA signaling. Arabidopsis plants unable to accumulate SA produced 25-fold higher levels of JA and showed enhanced expression of the JA-responsive genes LOX2, PDF1.2, and VSP in response to infection by Pseudomonas syringae pv tomato DC3000, indicating that in wild-type plants, pathogen-induced SA accumulation is associated with the suppression of JA signaling. Analysis of the Arabidopsis mutant npr1, which is impaired in SA signal transduction, revealed that the antagonistic effect of SA on JA signaling requires the regulatory protein NPR1. Nuclear localization of NPR1, which is essential for SA-mediated defense gene expression, is not required for the suppression of JA signaling, indicating that cross-talk between SA and JA is modulated through a novel function of NPR1 in the cytosol.

Arabidopsis Proteins↗