2,805 research outputs found

    Structure Thermolysis Relationships for Energetic Materials

    Get PDF
    The technique of fast thermolysis/FTIR spectroscopy, in which temperature profiling of the condensed phase is also conducted, is described. Applications are given to show how the formation of NO2, HONO, NO, and CH2O can be related to underlying parent molecular features. The effect of pressure in the 1-1000 psi range on the overall process is presented along with an example of how pressure can be used to distinguish the gas phase reactions from the condensed phase reactions during fast thermolysis

    Arrival At the Same Point: My Long, Winding, and Not-So-Circular Path to Professor

    Get PDF
    This is my story of the constant struggle between wanting both mathematics and motherhood, and realizing I could have it all but not all at once.The story involves earning degrees, securing a tenure-track position only to resign two years later, and then, through a gauntlet of adjunct and fixed-term positions, applying for and accepting another tenure-track position at the same institution, finally arriving back at the same point on the path I had been on sixteen years earlier. I walked this long, winding, and ultimately no-so-circular path while becoming and being a mother of four. It is my hope that this story inspires other mathematicians and mothers to carve their own path, and to know it does not have to look like the path most others have walked; it just has to be a path that works for them

    Replication factor-A from Saccharomyces cerevisiae is encoded by three essential genes coordinately expressed at S phase

    Get PDF
    Replication factor-A (RF-A) is a three-subunit protein complex originally purified from human cells as an essential component for SV40 DNA replication in vitro. We have previously identified a functionally homologous three-subunit protein complex from the yeast Saccharomyces cerevisiae. Here we report the cloning and characterization of the genes encoding RF-A from S. cerevisiae. Each of the three subunits is encoded by a single essential gene. Cells carrying null mutations in any of the three genes arrest as budded and multiply budded cells. All three genes are expressed in a cell-cycle-dependent manner; the mRNA for each subunit peaks at the G1/S-phase boundary. A comparison of protein sequences indicates that the human p34 subunit is 29% identical to the corresponding RFA2 gene product. However, expression of the human protein fails to rescue the rfa2::TRP1 disruption

    Interacting scalar and spinor fields in Bianchi type I universe filled with magneto-fluid

    Full text link
    Self-consistent system of spinor, scalar and BI gravitational fields in presence of magneto-fluid and Λ\Lambda-term is considered. Assuming that the expansion of the BI universe is proportional to the σ11\sigma_1^1 component of the shear tensor, exact solutions for the metric functions, as well as for scalar and spinor fields are obtained. For a non-positive Λ\Lambda the initially anisotropic space-time becomes isotropic one in the process of expansion, whereas, for Λ>0\Lambda > 0 an oscillatory mode of expansion of the BI model occurs.Comment: RevTex4, 8 pages, no figure

    Investigating Peer Review as an Intentional Learning Strategy to Foster Collaborative Knowledge-Building in Students of Instructional Design

    Get PDF
    Peer review has been advocated for as an intentional strategy to support the knowledge and skill attainment of adult learners preparing for professional practice, including those students preparing for instructional design and technology practice. The purposes of this article are to discuss the practical application of peer review as an instructional strategy by articulating its use in both face-to-face and online Instructional Design courses and to formulate directions for future research on the use of peer review in instructional practice. Findings from a literature review of student-to-student peer review and the authors\u27 experiences with the use of peer review in Instructional Design courses are used to foster a discussion that interweaves both important scholarly and practical elements

    Curvature tensors on distorted Killing horizons and their algebraic classification

    Full text link
    We consider generic static spacetimes with Killing horizons and study properties of curvature tensors in the horizon limit. It is determined that the Weyl, Ricci, Riemann and Einstein tensors are algebraically special and mutually aligned on the horizon. It is also pointed out that results obtained in the tetrad adjusted to a static observer in general differ from those obtained in a free-falling frame. This is connected to the fact that a static observer becomes null on the horizon. It is also shown that finiteness of the Kretschmann scalar on the horizon is compatible with the divergence of the Weyl component Ψ3\Psi_{3} or Ψ4\Psi_{4} in the freely falling frame. Furthermore finiteness of Ψ4\Psi_{4} is compatible with divergence of curvature invariants constructed from second derivatives of the Riemann tensor. We call the objects with finite Krestschmann scalar but infinite Ψ4\Psi_{4} ``truly naked black holes''. In the (ultra)extremal versions of these objects the structure of the Einstein tensor on the horizon changes due to extra terms as compared to the usual horizons, the null energy condition being violated at some portions of the horizon surface. The demand to rule out such divergencies leads to the constancy of the factor that governs the leading term in the asymptotics of the lapse function and in this sense represents a formal analog of the zeroth law of mechanics of non-extremal black holes. In doing so, all extra terms in the Einstein tensor automatically vanish.Comment: 21 pages, To appear in Class. Quant. Gra

    Quantum Creation of Topological Black Hole

    Get PDF
    The constrained instanton method is used to study quantum creation of a vacuum or charged topological black hole. At the WKBWKB level, the relative creation probability is the exponential of a quarter sum of the horizon areas associated with the seed instanton.Comment: Report-no change onl

    Black Hole Thermodynamics and Riemann Surfaces

    Get PDF
    We use the analytic continuation procedure proposed in our earlier works to study the thermodynamics of black holes in 2+1 dimensions. A general black hole in 2+1 dimensions has g handles hidden behind h horizons. The result of the analytic continuation is a hyperbolic 3-manifold having the topology of a handlebody. The boundary of this handlebody is a compact Riemann surface of genus G=2g+h-1. Conformal moduli of this surface encode in a simple way the physical characteristics of the black hole. The moduli space of black holes of a given type (g,h) is then the Schottky space at genus G. The (logarithm of the) thermodynamic partition function of the hole is the Kaehler potential for the Weil-Peterson metric on the Schottky space. Bekenstein bound on the black hole entropy leads us to conjecture a new strong bound on this Kaehler potential.Comment: 17+1 pages, 9 figure
    corecore