Case Report: Anterior Cruciate Ligament Calcification in a Patient With Chondrocalcinosis: Micro-Computed Tomography Presentation

In this case report, an incidental postoperative diagnosis of anterior cruciate ligament (ACL) calcification, associated with calcification of posterior cruciate ligament (PCL) and lateral meniscus insertions, was made using micro-computed tomography (μCT) technology in a knee specimen obtained during a total knee replacement (TKR) surgery due to painful tri-compartmental osteoarthritis (OA) with chondrocalcinosis signs at preoperative X-ray. Anterior cruciate ligament calcification is an uncommon finding, and conventional X-ray and MRI are not so helpful in its identification. μCT scan, in contrast, is of interest because it provides highly spatial three-dimensional information with excellent visualization of bones and calcifications. The μCT technology used in this case report allowed us to perform a detailed analysis and a 3-D reconstruction of the calcium pyrophosphate dihydrate (CPPD) crystal deposition about the knee without the need to section the specimens into slice as performed in previous studies. The 3-D model obtained with μCT scan permits to gain more insight into the shape of the calcification within the fibers of the ligamentous structures of the joint.

A new species of the hermit crab genus Diogenes (Crustacea: Decapoda: Diogenidae) from the coast of KwaZulu-Natal, South Africa

A new diogenid hermit crab with bright-white chelae, Diogenes albimanus n. sp., is described and illustrated, based on a single ovigerous female collected from KwaZulu-Natal, South Africa. The new species is compared to morphologically similar species, in particular to D. holthuisi and D. dorotheae, from which it is distinguishable by the shape and armature of the telson; and also to the superficially-similar South African D. extricatus, from which it differs by having the unarmed dorsal margins of the propodi and meri of the pereopods, as opposed to being armed with rows of strong spines. The unusually white chelae are similar in colour to those of D. takedai, but the coloration of all other parts is different in these two species. High quality macro photographs, a high-resolution microCT (μCT) scan of the whole animal, and the reference to the repository of the molecular barcode of the new species are provided.

The Two-Dimensional Aerodynamic Analysis of Various Cross-Sections of a Morphologically Accurate Bee Wing in Forward Flight

Bees sustain flight at extremely low Reynolds Numbers (500<Re<10,000) using three degrees of freedom and a flap frequency between 100 and 200 Hz. These combined mechanics create a complex vortex field that results in extraordinary agility and flight efficiency. In addition to agility and efficiency, bees are able to carry loads up to 80% of their body weight for miles making bee flight a very interesting subject area for drone and UAV related development. In order to better understand these complex fluid dynamics, Fluent is utilized to resolve the flow fields during forward flight for 4 anatomically accurate cross-sections of the bee wing at a speed of 1 m/s in two-dimensional flow. Each of the four cross-sections are taken at regular 1/6th wingspan intervals from the anatomically accurate bee wing model. The bee wing model was generated from a μCT scan of Bombus pensylvanicus with generalized bee kinematics presented in the literature. The kinematics applied to each cross-section are adjusted for the change in radial distance from the wing base. The presented analysis and discussion investigates the effects of the variation in cross-section and kinematics over the wing on vortex-shedding dynamics, and instantaneous aerodynamic forces.

Geometric modeling of 3D woven preforms in composite T-joints

A common method to fabricate net-shaped three-dimensional (3D) woven preforms for composite T-joints is to weave flat 3D preforms via a standard weaving machine with variation in binder yarn path and then separate the preform in the form of a bifurcation. Folding introduces fiber architecture deformation at the 3D woven bifurcation area. In this paper, a geometric modeling approach is proposed to represent the realistic fiber architecture, as a preprocessor for finite element analyses to predict composite structural performance. Supported by X-ray micro-computed tomography (µCT), three important deformation mechanisms are observed including yarn stack shifting, cross-section bending, and cross-section flattening resulting from the folding process. Furthermore, a set of mathematical formulae for simulation of the deformations in the junction region are developed and satisfactory agreement is observed when compared with μCT scan results.

Triadobatrachus massinoti, the earliest known lissamphibian (Vertebrata: Tetrapoda) re-examined by μCT scan, and the evolution of trunk length in batrachians

Triadobatrachus massinotiis a batrachian known from a single fossil from the Early Triassic of Madagascar that presents a combination of apomorphic salientian and plesiomorphic batrachian characters. Herein we offer a revised description of the specimen based on X-ray micro-tomography data. We report previously unknown caudal vertebrae, possible mentomeckelians, and hidden parts of other structures. We also confirm the presence of a ventrolateral ledge on the opisthotic, and we rectify some previous interpretations. There are no cervical ribs and the jaw may have had an angular. The presacral region is composed of 15 vertebrae with a unique atlas-axis complex instead of 14 vertebrae with a bipartite atlas. The configuration of the pelvic girdle is not very clear, although it is likely more plesiomorphic than the anuran- like condition previously assumed. Our re-assessment of the saltatorial performance of Triadobatrachussupports the traditional interpretation that this animal was not a specialised jumper. In order to assess the sequence of events in the early evolution of the salientian morphotype, we estimated the ancestral length of the trunk region of batrachians under different hypotheses of lissamphibian relationships and divergence times. Most of our results suggest that some trunk reduction took place before the divergence of caudates and salientians (presumably in the Permian), and that the trunk of Triadobatrachusmostly reflects this ancestral condition. Thus, trunk reduction possibly preceded the anteroposterior elongation of the ilia and the shortening of the tail seen in Triadobatrachus. We also provide an updated review of the data relevant for the use of Triadobatrachusas a calibration constraint in molecular divergence age analyses that meets recently-suggested standards.

Reproducibility of Bone Microstructure and Stiffness Measurements in Rats by In Vivo Micro Computed Tomography and Finite Element Analysis

Micro computed tomography (μCT) has been widely used to study 3-dimensional (3D) microstructure of bone specimens. In the recent decade, in vivo μCT scanners have become available to monitor longitudinal bone changes in rodents (1,2). The current in vivo μCT scan can obtain images with an isotropic voxel size up to 10.5 μm, which is high enough for direct 3D bone microstructural analyses. Moreover, based on these high-resolution images, micro finite element (μFE) models can be generated to estimate mechanical properties of bone. Therefore, by using in vivo μCT imaging and μFE analysis techniques, changes in geometry, microstructure, and mechanical properties of rodent bone, in response to either diseases or treatments, can be visualized and quantified over time.