1,817 research outputs found

    Compressed gas handbook

    Get PDF
    Handbook includes thermodynamic and related fluid flow data required to analyze high pressure compressible and incompressible fluid systems. Some theory and applications include thermodynamic fundamentals, gas behavior, adiabatic and isentropic flow, shock waves, flow measurement, and adiabatic and isothermal friction flow in pipes

    Fibronectin Contributes To Notochord Intercalation In The Invertebrate Chordate, Ciona Intestinalis

    Get PDF
    Background: Genomic analysis has upended chordate phylogeny, placing the tunicates as the sister group to the vertebrates. This taxonomic rearrangement raises questions about the emergence of a tunicate/vertebrate ancestor. Results: Characterization of developmental genes uniquely shared by tunicates and vertebrates is one promising approach for deciphering developmental shifts underlying acquisition of novel, ancestral traits. The matrix glycoprotein Fibronectin (FN) has long been considered a vertebrate-specific gene, playing a major instructive role in vertebrate embryonic development. However, the recent computational prediction of an orthologous “vertebrate-like” Fn gene in the genome of a tunicate, Ciona savignyi, challenges this viewpoint suggesting that Fn may have arisen in the shared tunicate/vertebrate ancestor. Here we verify the presence of a tunicate Fn ortholog. Transgenic reporter analysis was used to characterize a Ciona Fn enhancer driving expression in the notochord. Targeted knockdown in the notochord lineage indicates that FN is required for proper convergent extension. Conclusions: These findings suggest that acquisition of Fn was associated with altered notochord morphogenesis in the vertebrate/tunicate ancestor

    Cosmological simulations using a static scalar-tensor theory

    Full text link
    We present Λ\LambdaCDM NN-body cosmological simulations in the framework of a static general scalar-tensor theory of gravity. Due to the influence of the non-minimally coupled scalar field, the gravitational potential is modified by a Yukawa type term, yielding a new structure formation dynamics. We present some preliminary results and, in particular, we compute the density and velocity profiles of the most massive group.Comment: 4 pages, 6 figures, to appear in Journal of Physics: Conference Series: VII Mexican School on Gravitation and Mathematical Physics. 26 November to 1 December 2006, Playa del Carmen, Quintana Roo, Mexic

    Matrix Adhesion Polarizes Heart Progenitor Induction In The Invertebrate Chordate Ciona Intestinalis

    Get PDF
    Cell-matrix adhesion strongly influences developmental signaling. Resulting impacts on cell migration and tissue morphogenesis are well characterized. However, the in vivo impact of adhesion on fate induction remains ambiguous. Here, we employ the invertebrate chordate Ciona intestinalis to delineate an essential in vivo role for matrix adhesion in heart progenitor induction. In Ciona pre-cardiac founder cells, invasion of the underlying epidermis promotes localized induction of the heart progenitor lineage. We found that these epidermal invasions are associated with matrix adhesion along the pre-cardiac cell/epidermal boundary. Through targeted manipulations of RAP GTPase activity, we were able to manipulate pre-cardiac cell-matrix adhesion. Targeted disruption of pre-cardiac cell-matrix adhesion blocked heart progenitor induction. Conversely, increased matrix adhesion generated expanded induction. We were also able to selectively restore cell-matrix adhesion and heart progenitor induction through targeted expression of Ci-Integrin β2. These results indicate that matrix adhesion functions as a necessary and sufficient extrinsic cue for regional heart progenitor induction. Furthermore, time-lapse imaging suggests that cytokinesis acts as an intrinsic temporal regulator of heart progenitor adhesion and induction. Our findings highlight a potentially conserved role for matrix adhesion in early steps of vertebrate heart progenitor specification

    Potential--density pairs for spherical galaxies and bulges: the influence of scalar fields

    Full text link
    A family of potential--density pairs has been found for spherical halos and bulges of galaxies in the Newtonian limit of scalar--tensor theories of gravity. The scalar field is described by a Klein--Gordon equation with a source that is coupled to the standard Poisson equation of Newtonian gravity. The net gravitational force is given by two contributions: the standard Newtonian potential plus a term stemming from massive scalar fields. General solutions have been found for spherical systems. In particular, we compute potential--density pairs of spherical galactic systems, and some other astrophysical quantities that are relevant to generating initial conditions for spherical galaxy simulations.Comment: Paper accepted for publication in MNRAS, with four figure

    Cycle Ascension: 2023

    Get PDF
    Poster is of the Cycle Ascension: 2023 that is designed to maximize function and efficiency with an easy glide telescoping ramp feature, for effortless loading, without additional attachment parts or physical assistance.https://jdc.jefferson.edu/id/1006/thumbnail.jp
    • …
    corecore