Finite element analysis relating shape, material properties, and dimensions of taenioglossan radular teeth with trophic specialisations in Paludomidae (Gastropoda)

The radula, a chitinous membrane with embedded tooth rows, is the molluscan autapomorphy for feeding. The morphologies, arrangements and mechanical properties of teeth can vary between taxa, which is usually interpreted as adaptation to food. In previous studies, we proposed about trophic and other functional specialisations in taenioglossan radulae from species of African paludomid gastropods. These were based on the analysis of shape, material properties, force-resistance, and the mechanical behaviour of teeth, when interacting with an obstacle. The latter was previously simulated for one species (Spekia zonata) by the finite-element-analysis (FEA) and, for more species, observed in experiments. In the here presented work we test the previous hypotheses by applying the FEA on 3D modelled radulae, with incorporated material properties, from three additional paludomid species. These species forage either on algae attached to rocks (Lavigeria grandis), covering sand (Cleopatra johnstoni), or attached to plant surface and covering sand (Bridouxia grandidieriana). Since the analysed radulae vary greatly in their general size (e.g. width) and size of teeth between species, we additionally aimed at relating the simulated stress and strain distributions with the tooth sizes by altering the force/volume. For this purpose, we also included S. zonata again in the present study. Our FEA results show that smaller radulae are more affected by stress and strain than larger ones, when each tooth is loaded with the same force. However, the results are not fully in congruence with results from the previous breaking stress experiments, indicating that besides the parameter size, more mechanisms leading to reduced stress/strain must be present in radulae.

Prosopanche cocuccii (Hydnoraceae): a new species from Southern Brazil

Prosopanche cocuccii is described as a new species from Southern Brazil. It resembles P. bonacinae due to the trigonous rhizome and by the general size of the flower organs. Nevertheless, P. cocuccii is distinguished by the main floral morphological characteristics used to differentiate species. In addition, the new species presents some rare characters for the genus, such as a highly branched rhizome and flowers usually grouped in fascicles. We provide a description, illustrations, field photographs, morphological details under the stereomicroscope, and comments on habitat, ecology, distribution, and conservation of the new species, as well as an updated key for the genus Prosopanche. In addition, we identified that P. cocuccii produces a large number of rhizomes and fruits for each single host specimen of tobacco (Nicotiana tabacum), which resulted in a decrease in height and growth of its only known host plant.

An Investigation on Machining General Size Cylindrical Parts Using WEDM with Contour Approximation Method

The application of wire EDM to the machining of cylindrical parts is an emerging research topic. The current research is mainly focused on the machining of micro-cylindrical parts, and there is little research on the general-sized parts. This paper proposes to apply the principle of contour approximation method to the machining of cylindrical parts of general size. First, the basic principle of the contour approximation method is introduced, and the machining process is divided into three parts: roughing, semi-finishing and finishing. Roughing corresponds to polygon cutting. Second, the various indicators of polygon cutting are analyzed. The influence of the number of polygonal sides on the residual height and residual area is analyzed. Two methods are proposed for polygon cutting: sequential cutting and multiple edge cutting. The calculation formulas for the processing volume of the two methods are deduced. By comparing the two methods, it is found that different methods are applicable to different part sizes. At last, machining experiments were carried out. The selection of residual variables and the determination of polygon machining methods are detailed. The process parameters and machining time of each stage are listed. In addition, the measurement results of each stage of the machining are also analyzed.

Efficient size-bounded community search over large networks

The problem of community search, which aims to find a cohesive subgraph containing user-given query vertices, has been extensively studied recently. Most of the existing studies mainly focus on the cohesiveness of the returned community, while ignoring the size of the community, and may yield communities of very large sizes. However, many applications naturally require that the number of vertices/members in a community should fall within a certain range. In this paper, we design exact algorithms for the general size-bounded community search problem that aims to find a subgraph with the largest min-degree among all connected subgraphs that contain the query vertex q and have at least l and at most h vertices, where q, l, h are specified by the query. As the problem is NP-hard, we propose a branch-reduce-and-bound algorithm SC-BRB by developing nontrivial reducing techniques, upper bounding techniques, and branching techniques. Experiments on large real graphs show that SC-BRB on average increases the minimum degree of the community returned by the state-of-the-art heuristic algorithm GreedyF by a factor of 2.41 and increases the edge density by a factor of 2.2. In addition, SC-BRB is several orders of magnitude faster than a baseline approach, and all of our proposed techniques contribute to the efficiency of SC-BRB.

Morphological Variation of the Baka Pygmies’ Deciduous Second Molars

The Baka pygmies are known for their short stature resulting from a reduced growth rate during infancy. They are peculiar also for their teeth erupt earlier than in any other African population, and their posterior dentition is larger than in non-pygmies. However, the Baka’s dental morphology, as several other aspects of their biology, is still understudied. In this study we explore the Baka’s upper and lower second deciduous molars variation in comparison to a human sample including Africans, Asians, Europeans, and South Americans by means of 3D geometric morphometrics. We analyzed both the outer and inner aspect of the dental crowns, as well as their general size based on the natural logarithm of centroid sizes. Our results show largely overlapping morphologies between populations, especially for the lower molars. The distal region of the second molars is the most variable, with the Baka’s lower second molars showing the most extreme range of variation for this aspect and in terms of crown height. Upper and lower second molars showed high morphological covariation (RV=0.82). The Baka and South Americans’ second molars were confirmed among the largest in our sample. Despite of the Baka’s particular growth pattern, long-lasting isolation and extreme dental variation, it is not possible to distinguish them from other populations on the basis of their second molar morphology only.

Shared variability in body shape characters at growing phase of indigenous piglets

Body measurement traits, body length (BL) , rump height (RH), rump length (RL), rump width (RW), shoulder width (SW), wither height (WH), heart girth (HG), and flank length (FL) of 52 piglets of indigenous breed, managed under traditional system were obtained at birth and at weaning, to evaluate the sources of shared variability and efficiency of weight determination. Factor analysis reveals four factors accounting for 89.53% at birth and three factors accounting for 73.52% at weaning. Most common variability in body dimension at birth and at weaning could be accounted for by factors representing general size and RL in both cases. Body conformation “shape” was controlled by common and unique factors at both ages. Amount of variation associated with shape characters increased with advancing age and accuracy of weight estimation decreased with increase in age.