Insights into the Ecology and Evolutionary Success of Crocodilians Revealed through Bite-Force and Tooth-Pressure Experimentation

BackgroundCrocodilians have dominated predatory niches at the water-land interface for over 85 million years. Like their ancestors, living species show substantial variation in their jaw proportions, dental form and body size. These differences are often assumed to reflect anatomical specialization related to feeding and niche occupation, but quantified data are scant. How these factors relate to biomechanical performance during feeding and their relevance to crocodilian evolutionary success are not known.Methodology/Principal FindingsWe measured adult bite forces and tooth pressures in all 23 extant crocodilian species and analyzed the results in ecological and phylogenetic contexts. We demonstrate that these reptiles generate the highest bite forces and tooth pressures known for any living animals. Bite forces strongly correlate with body size, and size changes are a major mechanism of feeding evolution in this group. Jaw shape demonstrates surprisingly little correlation to bite force and pressures. Bite forces can now be predicted in fossil crocodilians using the regression equations generated in this research.Conclusions/SignificanceCritical to crocodilian long-term success was the evolution of a high bite-force generating musculo-skeletal architecture. Once achieved, the relative force capacities of this system went essentially unmodified throughout subsequent diversification. Rampant changes in body size and concurrent changes in bite force served as a mechanism to allow access to differing prey types and sizes. Further access to the diversity of near-shore prey was gained primarily through changes in tooth pressure via the evolution of dental form and distributions of the teeth within the jaws. Rostral proportions changed substantially throughout crocodilian evolution, but not in correspondence with bite forces. The biomechanical and ecological ramifications of such changes need further examination

Do people with benign joint hypermobility syndrome (BJHS) have reduced joint proprioception?:A systematic review and meta-analysis

Joint proprioceptive deficit is documented in a variety of musculoskeletal conditions including osteoarthritis, ligament and meniscal injuries, and individuals with increased joint hypermobility, such as those with Ehlers-Danlos. No systematic reviews have assessed joint proprioception in people with benign joint hypermobility syndrome (BJHS). This study addresses this to determine whether people with BJHS exhibit reduced joint proprioception, and, if so, whether this is evident in all age groups. The search strategy was conducted on 31st January 2013. The published literature was assessed using the databases: AMED, CINAHL, MEDLINE, EMBASE, PubMed and the Cochrane Library. Unpublished literature and trial registries were assessed including: OpenGrey, the WHO International Clinical Trials Registry Platform, Current Controlled Trials, the UK National Research Register Archive. All studies comparing the proprioceptive capability of people with and without BJHS were included. Study methodological quality was assessed using the CASP appraisal tool. Meta-analysis techniques were used when study homogeneity permitted. Five studies including 254 people were identified. People with BJHS demonstrated statistically significantly poorer lower limb joint position sense (JPS) (

Linear operators on the (LB)-sequence spaces ces(p−)ces(p-), 1 < p≤∞

We determine various properties of the regular (LB)-spaces (formula presented), generated by the family of Banach sequence spaces (formula presented). For instance, $ces(p-)$ is a (DFS)-space which coincides with a countable inductive limit of weighted $ell_1$-spaces; it is also Montel but not nuclear. Moreover, $ces(-p)$ and $ces(-q)$ are isomorphic as locally convex Hausdorff spaces for all choices of (formula presented). In addition, with respect to the coordinatewise order, $ces(p-)$ is also a Dedekind complete, reflexive, locally solid, lc-Riesz space with a Lebesgue topology. A detailed study is also made of various aspects (e.g., the spectrum, continuity, compactness, mean ergodicity, supercyclicity) of the Cesàro operator, multiplication operators and inclusion operators acting on such spaces (and between the spaces $ell_r$ and $ces(p-)$)

Prevalence data on all Ghent features in a cross-sectional study of 87 adults with proven Marfan syndrome

The prevalence of each single feature in the Ghent criteria in patients with Marfan syndrome (MFS) is not known. To elucidate this, a cross-sectional study of 105 adults with presumed MFS was carried out. All patients were examined by the same group of investigators with standardized and complete assessment of all features in the Ghent criteria. Eighty-seven (83%) fulfilled the criteria in 56 different variants. The most prevalent major criterion in Ghent-positive persons was dural ectasia (91%), followed by major genetic criterion (89%) and ectopic lenses (62 %). In 14 persons (16%), the diagnosis was dependent on the dural findings. In all, 79% fulfilled both major dural and major genetic (positive family history and/or FBN1 mutation) criteria, suggesting that most patients with MFS might be identified by investigating these criteria. A history or finding of ascending aortic disease was present in 46 patients (53%). This low prevalence might partly reflect a high number of diagnosed patients encompassing the whole spectrum of the syndrome. The study confirms the need to examine for the complete set of features in the Ghent criteria to identify all patients with MFS. The majority of persons with MFS might be identified by the combined assessment of dura mater and family history, supplemented with DNA analysis in family-negative cases. The low prevalence of ascending aortic disease might indicate better future prospects in an adult population than those traditionally considered