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The remarkable ecological and evolutionary success of ants was associated with the evolution of reproductive division of labor, in which sterile workers perform most colony tasks whereas reproductives become specialized in reproduction. In some lineages, the worker force became further subdivided into morphologically distinct subcastes (e.g. minor vs. major workers), allowing for the differential performance of particular roles in the colony. However, the functional and ecological significance of morphological differences between subcastes is not well understood. Here, we applied Finite Element Analysis (FEA) to explore the functional differences between major and minor ant worker mandibles. Analyses were carried out on mandibles of twoPheidolespecies, a dimorphic ant genus. In particular, we test whether major mandibles evolved to minimize stress when compared to minors using combinations of tooth and masticatory margin bites under strike and pressure conditions. Majors performed better in pressure conditions yet, contrary to our expectations, minors performed better in strike bite scenarios. Moreover, we demonstrate that even small morphological differences in ant mandibles might lead to substantial differences in biomechanical responses to bite loading. These results also underscore the potential of FEA to uncover biomechanical consequences of morphological differences within and between ant worker castes.

This work aims to verify the influence of characteristic compressive cylinder strength ( f c k), section geometry and eccentric axial load on the strength of square, cross, “T” and “L” reinforced concrete sections, under oblique composite flexion. A computational algorithm was created to calculate sections interaction diagram of bending strength, taking into account NBR 6118 idealized parabola-rectangle stress-strain relationships for 20 to 90 MPa f c k concretes. The results show that f c k influence is stronger for higher values of axial load and that the failure surface shape in interaction diagrams depends directly on the f c k and on the rebars distribution in the section. Furthermore, under lower compressive axial loads, higher oblique composite flexion strengths are reached when there is more reinforcement area in tension regions but, as the compression increases, the reinforcement presence and larger concrete areas in compression zones provide higher bending moment strengths. resumo: Este trabalho objetiva verificar a influência da variação da resistência do concreto ( f c k), da geometria da seção transversal e do esforço axial de compressão excêntrico na resistência à flexão composta oblíqua de seções com formato quadrado, “cruz”, “T” e “L”, com mesmas áreas de concreto e de armaduras. Para isso, cria-se um algoritmo computacional que calcula as envoltórias de resistência, aplicando os diagramas tensão-deformação propostos pela NBR 6118:2014 para concretos com f c k de 20 a 90 MPa. Os resultados revelam que o f c k exerce maior influência para esforços de compressão mais elevados e que o f c k e a distribuição das barras de aço interferem diretamente no formato das envoltórias. Mostra-se também que, sob compressões baixas, a concentração das barras de aço nas zonas de tração leva às maiores resistências mas, à medida que a compressão cresce, a presença da armadura e de maiores áreas de concreto nas zonas de maior compressão é que induzem momentos resistentes maiores.

Ants show remarkable ecological and evolutionary success due to their social life history and division of labour among colony members. In some lineages, the worker force became subdivided into morphologically distinct individuals (i.e. minor versus major workers), allowing for the differential performance of particular roles in the colony. However, the functional and ecological significance of these morphological differences are not well understood. Here, we applied finite element analysis (FEA) to explore the biomechanical differences between major and minor ant worker mandibles. Analyses were carried out on mandibles of two Pheidole species, a dimorphic ant genus. We tested whether major mandibles evolved to minimize stress when compared to minors using combinations of the apical tooth and masticatory margin bites under strike and pressure conditions. Majors performed better in pressure conditions yet, contrary to our expectations, minors performed better in strike bite scenarios. Moreover, we demonstrated that even small morphological differences in ant mandibles might lead to substantial differences in biomechanical responses to bite loading. These results also underscore the potential of FEA to uncover biomechanical consequences of morphological differences within and between ant workers.

Objetivo: O objetivo desse estudo foi avaliar e comparar as propriedades mecânicas dos cimentos resinosos duais convencionais e autoadesivos em macro e nanoescala. Métodos: Foram confeccionados 15 espécimes de cada marca de cimentos resinosos, AllCem (FGM), RelyX ARC (3M/ESPE) e RelyX U200 (3M/ESPE), para cada teste realizado (flexão de três pontos, compressão e nanoindentação) de acordo com as instruções dos fabricantes. Os espécimes foram fotoativados com aparelho Optilux Demetron (Kerr) por 40 segundos e armazenados em frascos escuros a 37ºC por 24 horas. Foram obtidos os resultados de resistência flexural, resistência à compressão, dureza e de módulo de Young para os diferentes testes mecânicos. Os dados foram avaliados pelos testes ANOVA, múltiplas comparações de Tukey HSD para análise dos valores de resistência, dureza e módulo de elasticidade entre os diferentes cimentos resinosos e ANOVA dois critérios e múltiplas comparações de Games Howell para análise dos módulos de Young entre os diferentes experimentos. Resultados: Os resultados revelaram que o AllCem obteve os maiores valores de resistência flexural e compressão axial (129±22,01 MPa; 243,71±29,75, respectivamente) e o RelyX U200 os menores valores (82,35±19,83 MPa; 134,57±48,93 MPa, respectivamente). Os valores de dureza não diferiram entre os cimentos estudados. No teste de flexão os valores de módulo de Young não diferiram entre os cimentos resinosos. No teste de compressão axial o AllCem apresentou módulo de Young estatisticamente maiores que dos demais cimentos. Para nanoindentação AllCem e RelyX U200 apresentaram maiores valores de módulo de Young que RelyX ARC. Os valores de módulo de Young diferiram significativamente entre todos os experimentos (p

Fractal geometry presents a comprehensive mathematical richness capable of describing different aspects of irregular growth phenomena of which the bone structure is an example. In this context we can mention osteoporosis, which is a disease that reaches the bones. It is characterized when the amount of bone mass decreases substantially and develops hollow bones, fine and extremely sensitive, more subject to fractures. It is a variation in the density of the trabecular bone, or a variation in the quantity of trabeculae. Generic modeling of an irregular structure, such as that of the trabeculae of bone, will allow an analytical description of the phenomena resulting from the structure of these trabeculae within the models of bone growth, bone remodeling, osseointegration, etc. In this way, the theoretical models of these phenomena may incorporate the fractal aspects of the trabeculae, explaining them more appropriately, as well as the properties deriving from their geometry in a general way. The objective of this work is to develop a methodology for the measurement of void volume variation and volume variation of trabecular bone material based on fractals.

O método lattice Boltzmann (LBM) foi proposto na década de 1980, fundamentado num modelo de lattice gas com a discretização da equação de transporte de Boltzmann. Esse método tem sido utilizado para retratar o fluxo sanguíneo pela possibilidade de simular computacionalmente a dinâmica de fluidos regida pelas equações de Navier-Stokes, conseguindo representar desde geometrias complexas até fluxos turbulentos e multifásicos. Com a necessidade de criar bons modelos físicos e matemáticos para representar o sistema cardiovascular humano (HCVS) é preciso utilizar teorias que analisem as leis físicas que regem o fluxo sanguíneo através de veias ou artérias do corpo humano. O objetivo deste trabalho é apresentar todo o processo de construção de um modelo idealizado para representar o fluxo sanguíneo em artérias, considerando um fluído newtoniano, viscoso, em regime laminar e pulsátil. A pulsação é definida conforme disposto por Womersley em seu artigo publicado em 1955 e posteriormente reproduzido com a utilização de diversos métodos numéricos por outros autores. Uma aplicação representativa de um trecho da artéria femoral ilustra o procedimento e os resultados são comparados com a literatura médica. Julgou-se que o modelo proposto para o fluxo pulsátil de um escoamento sanguíneo idealizado gerou resultados satisfatórios sob o ponto de vista qualitativo.

Introduction The aim of this study was to use the finite element method to evaluate the distribution of stresses and strains on the local bone tissue adjacent to the miniplate used for anchorage of orthodontic forces. Methods A 3-dimensional model composed of a hemimandible and teeth was constructed using dental computed tomographic images, in which we assembled a miniplate with fixation screws. The uprighting and mesial movements of the mandibular second molar that was anchored with the miniplate were simulated. The miniplate was loaded with horizontal forces of 2, 5, and 15 N. A moment of 11.77 N·mm was also applied. The stress and strain distributions were analyzed, and their correlations with the bone remodeling criteria and miniplate stability were assessed. Results When orthodontic loads were applied, peak bone strain remained within the range of bone homeostasis (100-1500 μ strain) with a balance between bone formation and resorption. The maximum deformation was found to be 1035 μ strain with a force of 5 N. At a force of 15 N, bone resorption was observed in the region of the screws. Conclusions We observed more stress concentration around the screws than in the cancellous bone. The levels of stress and strain increased when the force was increased but remained within physiologic levels. The anchorage system of miniplate and screws could withstand the orthodontic forces, which did not affect the stability of the miniplate.