The geometry of feather barbs (barb length and barb angle) determines feather vane asymmetry and vane rigidity, which are both critical to a feather's aerodynamic performance. Here, we describe the relationship between barb geometry and aerodynamic function across the evolutionary history of asymmetrical flight feathers, from Mesozoic taxa outside of modern avian diversity (Microraptor, Archaeo...

According to the Tits conjecture proved by Crisp and Paris, [CP], the subgroups of the braid group generated by proper powers of the Artin elements σi are presented by the commutators of generators which are powers of commuting elements. Hence they are naturally presented as right-angled Artin groups. The case of subgroups generated by powers of the band generators aij is more involved. We show...

In mathematics, a group is the set of symmetries of an object. Coxeter groups are a broad and natural class of groups that are related to reflectional symmetries. Each Coxeter group is determined by a diagram, called a labeled graph, that encodes algebraic information about the group. In general, two different labeled graphs can give rise to the same group. It is therefore natural to ask: are t...

UNLABELLED Although the use of zirconia abutments for implant-supported restorations has gained momentum with the increasing demand for esthetics, little informed design rationale has been developed to characterize their fatigue behavior under different clinical scenarios. However, to prevent the zirconia from fracturing, the use of a titanium connection in bi-component aesthetic abutments has ...

Recently, right-angled Artin groups have attracted much attention in geometric group theory. They have a rich structure of subgroups and nice algorithmic properties, and they give rise to cubical complexes with a variety of applications. This survey article is meant to introduce readers to these groups and to give an overview of the relevant literature. Artin groups span a wide range of groups ...

  Background: There are few studies comparing the biomechanical properties of angled blade plate and locking compression plates in supracondylar osteotomy. In the current randomized study, we prospectively compared the clinical and radiological outcomes of supracondylar osteotomy using these two plates. Methods: Forty patients with valgus knee malalignment were randomly assigned to two equal nu...

A total of 2,261 2-stage implants was placed in 467 patients in combination with angled abutments ranging from 0 to 45 degrees. These were observed over a period of up to 96 months, with a mean observation time of 28.8 months. Single and multiple teeth were replaced and restored using angled abutments. For patients who contributed multiple survival data, the data were considered dependent. Ther...

OBJECTIVES The angled blade plate has been the historical standard in fixed-angle extramedullary subtrochanteric femur fracture fixation, but it requires an extensile lateral approach to the femur. Little formal evaluation exists for specifically designed percutaneous extramedullary implants. The purpose of this study was to compare 3 locked plating constructs, all with percutaneous insertion c...

Background: Shearing is a fast and inexpensive method to cut sheet metal that has been used since the beginning of the industrialism. Consequently, published experimental studies of shearing can be found from over a century back in time. Recent studies, however, are due to the availability of low-cost digital computation power, mostly based on finite element simulations that guarantees quick re...

FOR MANY YEARS ANGIOCARDIOGRAPHIC DIAGNOSIS in patients with congenital heart disease has been primarily dependent upon frontal (vertical) and lateral (horizontal) projections. Oblique views have been recognized as helpful, but their use has been limited by the inconvenience and delay caused by repositioning of an infant or child on the catheterization table. The same reluctance to turn or move...