Morphometry of the Cranial Base in Subjects with Class III Malocclusion

The significance of the cranial base in the development of Class III malocclusion remains uncertain. The purpose of this study was to determine whether the form of the cranial base differs between prepubertal Class I and Class III subjects. Lateral cephalographs of 73 children of European-American descent aged between 5 and 11 years with Class III malocclusion were compared with those of their counterparts with a normal, Class I molar occlusion. The cephalographs were traced, checked, and subdivided into seven age- and sex-matched groups. Average geometries, scaled to an equivalent size, were generated based on 13 craniofacial landmarks by means of Procrustes analysis, and these configurations were statistically tested for equivalence. Bivariate and multivariate analyses utilizing 5 linear and angular measurements were undertaken to corroborate the Procrustes analysis. Graphical analysis, utilizing thin-plate spline and finite element methods, was performed for localization of differences in cranial base morphology. Results indicated that cranial base morphology differed statistically for all age-wise comparisons. Graphical analysis revealed that the greatest differences in morphology occurred in the posterior cranial base region, which generally consisted of horizontal compression, vertical expansion, and size contraction. The sphenoidal region displayed expansion, while the anterior regions showed shearing and local increases in size. It is concluded that the shape of the cranial base differs in subjects with Class III malocclusion compared with the normal Class I configuration, due in part to deficient orthocephalization, or failure of the cranial base to flatten during development.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67377/2/10.1177_00220345970760021101.pd

Inconsistent impacts of decomposer diversity on the stability of aboveground and belowground ecosystem functions

The intensive discussion on the importance of biodiversity for the stability of essential processes in ecosystems has prompted a multitude of studies since the middle of the last century. Nevertheless, research has been extremely biased by focusing on the producer level, while studies on the impacts of decomposer diversity on the stability of ecosystem functions are lacking. Here, we investigate the impacts of decomposer diversity on the stability (reliability) of three important aboveground and belowground ecosystem functions: primary productivity (shoot and root biomass), litter decomposition, and herbivore infestation. For this, we analyzed the results of three laboratory experiments manipulating decomposer diversity (1–3 species) in comparison to decomposer-free treatments in terms of variability of the measured variables. Decomposer diversity often significantly but inconsistently affected the stability of all aboveground and belowground ecosystem functions investigated in the present study. While primary productivity was mainly destabilized, litter decomposition and aphid infestation were essentially stabilized by increasing decomposer diversity. However, impacts of decomposer diversity varied between plant community and fertility treatments. There was no general effect of the presence of decomposers on stability and no trend toward weaker effects in fertilized communities and legume communities. This indicates that impacts of decomposers are based on more than effects on nutrient availability. Although inconsistent impacts complicate the estimation of consequences of belowground diversity loss, underpinning mechanisms of the observed patterns are discussed. Impacts of decomposer diversity on the stability of essential ecosystem functions differed between plant communities of varying composition and fertility, implicating that human-induced changes of biodiversity and land-use management might have unpredictable effects on the processes mankind relies on. This study therefore points to the necessity of also considering soil feedback mechanisms in order to gain a comprehensive and holistic understanding of the impacts of current global change phenomena on the stability of essential ecosystem functions

Plant Diversity Surpasses Plant Functional Groups and Plant Productivity as Driver of Soil Biota in the Long Term

One of the most significant consequences of contemporary global change is the rapid decline of biodiversity in many ecosystems. Knowledge of the consequences of biodiversity loss in terrestrial ecosystems is largely restricted to single ecosystem functions. Impacts of key plant functional groups on soil biota are considered to be more important than those of plant diversity; however, current knowledge mainly relies on short-term experiments.We studied changes in the impacts of plant diversity and presence of key functional groups on soil biota by investigating the performance of soil microorganisms and soil fauna two, four and six years after the establishment of model grasslands. The results indicate that temporal changes of plant community effects depend on the trophic affiliation of soil animals: plant diversity effects on decomposers only occurred after six years, changed little in herbivores, but occurred in predators after two years. The results suggest that plant diversity, in terms of species and functional group richness, is the most important plant community property affecting soil biota, exceeding the relevance of plant above- and belowground productivity and the presence of key plant functional groups, i.e. grasses and legumes, with the relevance of the latter decreasing in time.Plant diversity effects on biota are not only due to the presence of key plant functional groups or plant productivity highlighting the importance of diverse and high-quality plant derived resources, and supporting the validity of the singular hypothesis for soil biota. Our results demonstrate that in the long term plant diversity essentially drives the performance of soil biota questioning the paradigm that belowground communities are not affected by plant diversity and reinforcing the importance of biodiversity for ecosystem functioning

Politicization of administrative elites in Western Europe: an introduction

The Institutions of Politics; Design, Workings, and implications ( do not use, ended 1-1-2020

Estudo comparativo cefalométrico dos padrões dentofaciais de indivíduos portadores de oclusão normal e de más oclusões de Angle Comparative cephalometric study of dentofacial patterns of individuals with normal occlusion and Angle malocclusions

OBJETIVO: avaliar os padrões dentofaciais de pacientes portadores de oclusão normal e más oclusões de Angle quanto a possíveis diferenças entre as grandezas estudadas, em relação ao sexo, dentro de cada grupo e entre os grupos. MÉTODOS: a amostra constou de 200 telerradiografias cefalométricas laterais obtidas de jovens brasileiros, de ambos os sexos, na faixa etária de 11 anos e 2 meses a 19 anos e 10 meses, apresentando dentição permanente. O material foi dividido, quanto ao tipo de oclusão, em cinco grupos: um de pacientes portadores de oclusão normal, e quatro de pacientes portadores de más oclusões de Angle, sendo cada grupo dividido igualmente quanto ao sexo. Foram avaliadas grandezas cefalométricas angulares e lineares. RESULTADOS: na grande maioria das grandezas, os sexos masculino e feminino não diferiram; entre os grupos, a posição da maxila não mostrou diferença significativa, o retrognatismo mandibular foi marcante nos grupos de Classe II divisões 1ª e 2ª e foram observados alguns desequilíbrios verticais com diferenças significativas; o padrão foi hipodivergente para os grupos de oclusão normal e Classe II, divisão 2ª, e neutro para os grupos de Classe I; Classe II, divisão 1ª; e Classe III; a compensação dentoalveolar foi evidente nos grupos de Classe III e de Classe II, divisão 2ª; o grupo de oclusão normal apresentou perfil mais convexo que os padrões americanos. CONCLUSÃO: foi possível configurar, de forma geral, algumas características da morfologia facial para alguns tipos de más oclusões. Entretanto, existe a necessidade de avaliar a face individualmente, pois algumas características permeiam entre os diferentes tipos de oclusão.<br>OBJECTIVE: To determine the dentofacial patterns in patients presenting normal occlusion and Angle malocclusions, evaluating the possible differences in the studied measurements, considering the gender, the differences within each group and the differences among the groups. METHODS: The sample comprised 200 lateral cephamometric radiographs of young Brazilian subjects, from both genders, with average age between 11 years and 2 months and 19 years and 10 months. The sample was classified according to the type of occlusion into five groups: one group with subjects presenting normal malocclusions, and four groups with subjects presenting Angle malocclusions. Each group was equally divided according to the gender of subjects. Angular and linear measurements were evaluated in this study. RESULTS: For most measurements, males and females did not differ; among the groups, the position of the maxilla did not show a significant difference, mandibular retrognathia was notable in the groups with Class II division 1 and 2, with a few vertical imbalances with significant differences were observed; the pattern was hypodivergent for the groups with normal occlusion and Class II division 1; and neutral for Class I, Class II division 1 and Class III groups; dentoalveolar compensation was evident in Class III and Class II division 2 groups; the normal occlusion group had a more convex profile than American standards. CONCLUSION: It was possible to generally construct a few characteristics of facial morphology for some types of malocclusion. However, there is the need to individually evaluate each face, as some characteristics prevail among the different occlusion types