Evolutionary analysis of swimming speed in early vertebrates challenges the ‘New Head Hypothesis’

The ecological context of early vertebrate evolution is envisaged as a long-term trend towards increasingly active food acquisition and enhanced locomotory capabilities culminating in the emergence of jawed vertebrates. However, support for this hypothesis has been anecdotal and drawn almost exclusively from the ecology of living taxa, despite knowledge of extinct phylogenetic intermediates that can inform our understanding of this formative episode. Here we analyse the evolution of swimming speed in early vertebrates based on caudal fin morphology using ancestral state reconstruction and evolutionary model fitting. We predict the lowest and highest ancestral swimming speeds in jawed vertebrates and microsquamous jawless vertebrates, respectively, and find complex patterns of swimming speed evolution with no support for a trend towards more active lifestyles in the lineage leading to jawed groups. Our results challenge the hypothesis of an escalation of Palaeozoic marine ecosystems and shed light into the factors that determined the disparate palaeobiogeographic patterns of microsquamous versus macrosquamous armoured Palaeozoic jawless vertebrates. Ultimately, our results offer a new enriched perspective on the ecological context that underpinned the assembly of vertebrate and gnathostome body plans, supporting a more complex scenario characterized by diverse evolutionary locomotory capabilities reflecting their equally diverse ecologies

Novel Microscopic Mechanism of Intermixing during Growth on Soft Metallic Substrates

Generic computer simulations using empiric interatomic potentials suggest a new, collective mechanism that could be responsible for mixing at heteroepitaxial interfaces. Even if single adsorbate atoms diffuse by hopping on the substrate surface and do not mix at the terraces, two-dimensional islands formed by nucleation may become unstable above a certain critical size and explode upwards forming clusters of several atomic layers. This process is accompanied by strong distortions of the underlying atomic layers, and on soft materials it can result in surface etching and incorporation of substrate atoms into the islands.Fil: Gomez, Liliana Maria. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; ArgentinaFil: Slutzky, Claudia Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Ferron, Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: de la Figuera, J.. Sandia National Laboratories; Estados UnidosFil: Camarero, J.. Universidad Autónoma de Madrid; EspañaFil: Vazquez de Parga, A.. Universidad Autónoma de Madrid; EspañaFil: de Miguel, J.J.. Universidad Autónoma de Madrid; EspañaFil: Miranda, R.. Universidad Autónoma de Madrid; Españ

The Stargazin-Related Protein {gamma}7 Interacts with the mRNA-Binding Protein Heterogeneous Nuclear Ribonucleoprotein A2 and Regulates the Stability of Specific mRNAs, Including CaV2.2

The role(s) of the novel stargazin-like {gamma}-subunit proteins remain controversial. We have shown previously that the neuron-specific {gamma}7 suppresses the expression of certain calcium channels, particularly CaV2.2, and is therefore unlikely to operate as a calcium channel subunit. We now show that the effect of {gamma}7 on CaV2.2 expression is via an increase in the degradation rate of CaV2.2 mRNA and hence a reduction of CaV2.2 protein level. Furthermore, exogenous expression of {gamma}7 in PC12 cells also decreased the endogenous CaV2.2 mRNA level. Conversely, knockdown of endogenous {gamma}7 with short-hairpin RNAs produced a reciprocal enhancement of CaV2.2 mRNA stability and an increase in endogenous calcium currents in PC12 cells. Moreover, both endogenous and expressed {gamma}7 are present on intracellular membranes, rather than the plasma membrane. The cytoplasmic C terminus of {gamma}7 is essential for all its effects, and we show that {gamma}7 binds directly via its C terminus to a heterogeneous nuclear ribonucleoprotein (hnRNP A2), which also binds to a motif in CaV2.2 mRNA, and is associated with native CaV2.2 mRNA in PC12 cells. The expression of hnRNP A2 enhances CaV2.2 IBa, and this enhancement is prevented by a concentration of {gamma}7 that alone has no effect on IBa. The effect of {gamma}7 is selective for certain mRNAs because it had no effect on {alpha}2{delta}-2 mRNA stability, but it decreased the mRNA stability for the potassium-chloride cotransporter, KCC1, which contains a similar hnRNP A2 binding motif to that in CaV2.2 mRNA. Our results indicate that {gamma}7 plays a role in stabilizing CaV2.2 mRNA

Roadmap for BIM Adoption and Implementation by Small-Sized Construction Companies

Building Information Modeling (BIM) offers a variety of tools to help a wide range of stakeholders in the construction industry. There has been substantial research on the advantages and challenges of implementing BIM for large and medium-sized construction companies; however, there is a dearth of research on the benefits and challenges faced by smaller construction firms when adopting and implementing BIM. Thus, this study focuses on developing a BIM Adoption Roadmap that can be used as a starting point by small-sized construction companies. To achieve this objective, first, medium and large-sized construction firms who already have implemented BIM in several of their projects were interviewed. The purpose of these interviews was to understand what motivated these firms to start using BIM. Based on the findings from the interviews, a set of survey questions was prepared and distributed among all types of construction firms in order to identify which BIM functions they use. The semi-structured survey included questions regarding company demographics, innovativeness, and BIM-specific topics. A second survey was sent out to collect feedback on the proposed BIM Adoption Roadmap from large and small-sized construction companies. The roadmap for small-sized construction companies aims to help them adopt at least one of the BIM functions identified in this study. The idea is to have small-sized construction companies to start implementing simple and easy BIM functions in some of their projects and then explore other BIM applications in the future

Measuring Low Intensity Light Reflections of High Temperature CO₂ Adsorbed on SiO₂ Near Brewster's Angle

This investigation expands on earlier methods of using surface polarization reflection (SPR) to characterize the first few monolayers of a surface. Past research measured intensities of light reflecting off an SiO₂ optical flat inside a vacuum. Pressure of applied gas was changed to view a change in reflection. In an attempt to remove the need of a vacuum chamber, this experiment was run in the open air. P-polarized light is reflected at Brewster's angle to measure low intensity reflections. Using an SBIG 8300 CCD camera intensities are measured in an open air environment and compared to that of applied CO₂ by the use of a gas jet. SPR theory predicts that higher polarizabilities will cause a larger reflection. Temperature of the applied gas was increased in order to quantify a difference in reflections based on this change in temperature. Removing ambient particles from the open air by use of a heated gas stream was thought to change the signal to a more consistent level of measurement. The intensity was found to change at higher temperatures but no trend was quantified. Increasing the temperature beyond 323K caused signal fluctuation and was found not to be beneficial in SPR analysis. SPR was found to not have been improved by heating the applied gas

Imaging benign inflammatory syndromes

AbstractBenign mastitis is a rare disease and its management is difficult. The diagnostic challenge is to distinguish it from carcinomatous mastitis. We make a distinction between acute mastitis secondary to an infection, to inflammation around a benign structure or to superficial thrombophlebitis, and chronic, principally plasma cell and idiopathic granulomatous mastitis. Imaging is often non-specific but we need to know and look for certain ultrasound, mammogram or magnetic resonance imaging (MRI) signs to give a pointer as early as possible towards a benign aetiology. A biopsy should be undertaken systematically where there is the slightest diagnostic doubt, to avoid failing to recognise a carcinomatous mastitis