RESUMO
We investigate symmetry-breaking bifurcation patterns in evolution in the framework of adaptive dynamics (AD). We define weak and strong symmetry. The former applies for populations where only the simultaneous reflection of all individuals is an invariant transformation. The symmetry is strong in populations where reflection of some, but not all, individuals leaves the situation unchanged. We show that in case of weak symmetry evolutionary branching can lead to the emergence of two asymmetric variants, which are mirror images of each other, and the loss of the symmetric ancestor. We also show that in case of strong symmetry, evolutionary branching can occur into a symmetric and an asymmetric variant, both of which survive. The latter, asymmetric branching differs from the generic branching patterns of AD, which is always symmetric. We discuss biological examples for weak and strong symmetries and a specific model producing the new kind of branching.
Assuntos
Evolução Biológica , Genética Populacional , Animais , Modelos Estatísticos , Dinâmica PopulacionalAssuntos
Ortodontia Corretiva/métodos , Anormalidades Dentárias/genética , Raiz Dentária/anormalidades , Adolescente , Anodontia/diagnóstico por imagem , Anodontia/genética , Anodontia/reabilitação , Criança , Humanos , Contenções Ortodônticas , Ortodontia Corretiva/instrumentação , Radiografia Panorâmica , Anormalidades Dentárias/diagnóstico por imagem , Anormalidades Dentárias/terapia , Raiz Dentária/diagnóstico por imagemRESUMO
The advantage and disadvantage of applying ceramic orthodontic brackets were compared on base of practical experiences. The application of ceramic brackets is recommended in the clinical practice, considering that also enamel injuries may develop by debonding.
Assuntos
Braquetes Ortodônticos , Adolescente , Cerâmica , Esmalte Dentário/lesões , Feminino , Humanos , Masculino , Braquetes Ortodônticos/efeitos adversosAssuntos
Substitutos Sanguíneos/farmacocinética , Hemoglobinas/farmacocinética , Lipossomos , Neutrófilos/metabolismo , Substitutos Sanguíneos/administração & dosagem , Soluções Tampão , Hemoglobinas/administração & dosagem , Humanos , Técnicas In Vitro , Taxa de Depuração Metabólica , Fagocitose , Fosfatos , Plasma/metabolismoRESUMO
The authors report about a 3 years examination of children wearing fixed orthodontic appliances. The patient were divided into three groups (each comprising 70 persons): 1. Elmex fluid, 2. Elmex gel, 3. control group. Increase of caries intensity was lower while condition of the gingiva was better in the groups using aminofluoride preparations. Good results were obtained especially by employing the Elmex gel.
Assuntos
Aminas/administração & dosagem , Fluoretos , Ortodontia Corretiva/métodos , Aminas/uso terapêutico , Cariostáticos/uso terapêutico , Criança , Cárie Dentária/prevenção & controle , Placa Dentária/prevenção & controle , Diaminas , Fluoretos Tópicos/administração & dosagem , Humanos , Aparelhos Ortodônticos/efeitos adversosRESUMO
The effect of the laxative component rhein on electrical properties and Cl transport was investigated in partially stripped epithelial sheets of rabbit distal colon under short-circuit conditions. Whereas mucosal rhein had no effect, serosally applied rhein stimulated electrogenic Cl secretion in a dose-dependent manner with a half-maximal stimulation at 0.05 mmol/l. The stimulation was partially reversible by serosal bumetanide. Indomethacin preincubation inhibited the effect of rhein, but did not prevent theophylline-induced Cl secretion. The results suggest a prostaglandin-mediated effect of rhein on the apical Cl conductance of the colonic cells.
