Minimal model for aeolian sand dunes

We present a minimal model for the formation and migration of aeolian sand dunes. It combines a perturbative description of the turbulent wind velocity field above the dune with a continuum saltation model that allows for saturation transients in the sand flux. The latter are shown to provide the characteristic length scale. The model can explain the origin of important features of dunes, such as the formation of a slip face, the broken scale invariance, and the existence of a minimum dune size. It also predicts the longitudinal shape and aspect ratio of dunes and heaps, their migration velocity and shape relaxation dynamics. Although the minimal model employs non-local expressions for the wind shear stress as well as for the sand flux, it is simple enough to serve as a very efficient tool for analytical and numerical investigations and to open up the way to simulations of large scale desert topographies.Comment: 19 pages, 22 figure

ANÁLISE CLÍNICA E HISTOLÓGICA DA UTILIZAÇÃO DA RESINA ACRÍLICA AUTOPOLIMERIZÁVEL NAS FRATURAS DE MANDÍBULA E MAXILA E SEPARAÇÃO DA SÍNFISE MENTONIANA EM CÃES E GATOS CLINICAL AND HISTOLOGICAL EVALUATION OF ACRYLIC RESIN IN THE FRACTURE OF THE MANDIBLE AND MAXILLA AND SEPARATION OF MANDIBULAR SYMPHISIS IN DOGS AND CATS

O trabalho foi desenvolvido em duas fases. A primeira constou de aplicação de resina acrílica autopolimerizável sobre dentes de cães experimentais, sem condicionamento ácido do esmalte dental; a gengiva foi analisada histologicamente nos períodos de um, três, sete, 14, 21 e 30 dias. A segunda fase foi conduzida em 20 cães e 10 gatos com fraturas do sistema estomatognático, atendidos no Ambulatório Central da FMVZ/USP. Nessa segunda fase, clínica, foi aplicado condicionamento ácido do esmalte. A resina era usada nas fraturas rostrais às raízes distais do primeiro molar inferior e do quarto pré-molar superior, bem como na separação da sínfise mentoniana. Os resultados da primeira fase mostraram que mesmo sem o condicionamento ácido houve aderência da resina acrílica sobre os dentes, embora houvesse necessidade de maior volume do material, o que provocou ulcerações dos tecidos moles da boca. Essa fase também evidenciou, à sondagem, que o epitélio de aderência sulcular permaneceu aderido, além de gengivite, ulceração da gengiva, língua e mucosa alveolar. A análise histológica revelou predominantemente ulceração dos tecidos em contato com a resina. Na segunda fase, todos os animais evidenciaram consolidação óssea das fraturas, além de gengivite e ulceração. Lesões periodontais foram encontradas em dois animais dos quais a resina foi removida tardiamente, com quatro e 12 meses após a aplicação, respectivamente. Em ambas as fases, os animais adaptaram-se bem à resina sobre os dentes.<br>This paper was performed in two phases. In the first one, the stability of the acrylic resin over the teeth of dogs, without enamel acid conditioning, the clinical and histological reaction on the gingiva were analyzed in periods of 1, 3, 7, 14, 21 and 30 days. The second phase was conducted in 20 dogs and 10 cats, with acid etching technique. The resin was used in the rostral fractures to the distal roots of the lower first molar and upper fourth premolar, as well as in the separation of the symphisis. The results of the first phase indicated that even without the acid etching technique, the acrylic resin remained fixed over the teeth, although a higher volume of resin was needed, thus inducing more areas of ulceration on the lips, gingiva and tongue. This phase also demonstrated that the sulcular gingival adhesion epithelium remained attached to the teeth. Gingivitis, ulceration on the gingiva, tongue and alveolar mucosa were also observed. The histologic analyses mainly showed ulceration of the gingival epithelium. In the second phase all animals featured clinical bone healing in the site of fracture, as well as gingivitis and ulceration. Periodontitis was found in two animals whose resin was not removed up to four and twelve months after application of the acrylic resin. The results also showed that the method can be used in fractures rostral to the distal roots of upper fourth pre-molar an first lower molar

Association of Genetic Variants With Primary Open-Angle Glaucoma Among Individuals With African Ancestry

Item does not contain fulltextImportance: Primary open-angle glaucoma presents with increased prevalence and a higher degree of clinical severity in populations of African ancestry compared with European or Asian ancestry. Despite this, individuals of African ancestry remain understudied in genomic research for blinding disorders. Objectives: To perform a genome-wide association study (GWAS) of African ancestry populations and evaluate potential mechanisms of pathogenesis for loci associated with primary open-angle glaucoma. Design, Settings, and Participants: A 2-stage GWAS with a discovery data set of 2320 individuals with primary open-angle glaucoma and 2121 control individuals without primary open-angle glaucoma. The validation stage included an additional 6937 affected individuals and 14917 unaffected individuals using multicenter clinic- and population-based participant recruitment approaches. Study participants were recruited from Ghana, Nigeria, South Africa, the United States, Tanzania, Britain, Cameroon, Saudi Arabia, Brazil, the Democratic Republic of the Congo, Morocco, Peru, and Mali from 2003 to 2018. Individuals with primary open-angle glaucoma had open iridocorneal angles and displayed glaucomatous optic neuropathy with visual field defects. Elevated intraocular pressure was not included in the case definition. Control individuals had no elevated intraocular pressure and no signs of glaucoma. Exposures: Genetic variants associated with primary open-angle glaucoma. Main Outcomes and Measures: Presence of primary open-angle glaucoma. Genome-wide significance was defined as P C) with primary open-angle glaucoma (odds ratio [OR], 1.32 [95% CI, 1.20-1.46]; P = 2 x 10-8). The association was validated in an analysis of an additional 6937 affected individuals and 14917 unaffected individuals (OR, 1.15 [95% CI, 1.09-1.21]; P < .001). Each copy of the rs59892895*C risk allele was associated with increased risk of primary open-angle glaucoma when all data were included in a meta-analysis (OR, 1.19 [95% CI, 1.14-1.25]; P = 4 x 10-13). The rs59892895*C risk allele was present at appreciable frequency only in African ancestry populations. In contrast, the rs59892895*C risk allele had a frequency of less than 0.1% in individuals of European or Asian ancestry. Conclusions and Relevance: In this genome-wide association study, variants at the APBB2 locus demonstrated differential association with primary open-angle glaucoma by ancestry. If validated in additional populations this finding may have implications for risk assessment and therapeutic strategies