2,546 research outputs found

    A Status Report Lockheed Launch Vehicle

    Get PDF
    This paper discusses a new family of small and medium space launch vehicles being developed by Lockheed Missiles & Space Company, Inc. The development program will culminate in a demonstration launch in November 1994. The paper gives a brief background and gives the program status as of the date of this paper. Supporting graphics are included

    Exploring potential germline associated roles of the TRIM-NHL protein NHL-2 through RNAi screening

    Get PDF
    TRIM-NHL proteins are highly conserved regulators of developmental pathways in vertebrates and invertebrates. The TRIM-NHL family member NHL-2 in Caenorhabditis elegans functions as a miRNA cofactor to regulate developmental timing. Similar regulatory roles have been reported in other model systems, with the mammalian ortholog in mice, TRIM32, contributing to muscle and neuronal cell proliferation via miRNA activity. Given the interest associated with TRIM-NHL family proteins, we aimed to further investigate the role of NHL-2 in C. elegans development by using a synthetic RNAi screening approach. Using the ORFeome library, we knocked down 11,942 genes in wild-type animals and nhl-2 null mutants. In total, we identified 42 genes that produced strong reproductive synthetic phenotypes when knocked down in nhl-2 null mutants, with little or no change when knocked down in wild-type animals. These included genes associated with transcriptional processes, chromosomal integrity, and key cofactors of the germline small 22G RNA pathway.Gregory M. Davis, Wai Y. Low, Joshua W.T. Anderson and Peter R. Boa

    3D seismic imaging of buried Younger Dryas mass movement flows: Lake Windermere, UK

    No full text
    Windermere is a glacially overdeepened lake located in the southeastern Lake District, UK. Using the threedimensional(3D) Chirp subbottom profiler, we image mass movement deposits related to the Younger Dryas(YD) within a decimetre-resolution 3D seismic volume, documenting their internal structure and interactionwith preexisting deposits in unprecedented detail. Three distinct flow events are identified and mappedthroughout the 3D survey area. Package structures and seismic attributes classify them as: a small (totalvolume of c. 1500 m3) debris flow containing deformed translated blocks; a large (inferred total volume ofc. 500,000 m3), homogeneous fine-grained mass flow deposit; and a debris flow (inferred total volume ofc. 60,000 m3) containing small (c. 8.0×2.0 m) deformed translated blocks. Geomorphological mapping oftheir distribution and interaction with preexisting sediments permit the reconstruction of a depositionalhistory for the stratigraphic units identified in the seismic volume.<br/

    The maximal energy of classes of integral circulant graphs

    Full text link
    The energy of a graph is the sum of the moduli of the eigenvalues of its adjacency matrix. We study the energy of integral circulant graphs, also called gcd graphs, which can be characterized by their vertex count nn and a set D\cal D of divisors of nn in such a way that they have vertex set Zn\mathbb{Z}_n and edge set a,b:a,bZn,gcd(ab,n)D{{a,b}: a,b\in\mathbb{Z}_n, \gcd(a-b,n)\in {\cal D}}. For a fixed prime power n=psn=p^s and a fixed divisor set size D=r|{\cal D}| =r, we analyze the maximal energy among all matching integral circulant graphs. Let pa1<pa2<...<parp^{a_1} < p^{a_2} < ... < p^{a_r} be the elements of D{\cal D}. It turns out that the differences di=ai+1aid_i=a_{i+1}-a_{i} between the exponents of an energy maximal divisor set must satisfy certain balance conditions: (i) either all did_i equal q:=s1r1q:=\frac{s-1}{r-1}, or at most the two differences [q][q] and [q+1][q+1] may occur; %(for a certain dd depending on rr and ss) (ii) there are rules governing the sequence d1,...,dr1d_1,...,d_{r-1} of consecutive differences. For particular choices of ss and rr these conditions already guarantee maximal energy and its value can be computed explicitly.Comment: Discrete Applied Mathematics (2012

    Molecular clouds as hubs in spiral galaxies : gas inflow and evolutionary sequence

    Get PDF
    We decomposed the molecular gas in the spiral galaxy NGC 628 (M74) into multi-scale hub-filament structures using the CO (2−1) line by the dendrogram algorithm. All leaf structures as potential hubs were classified into three categories, i.e. leaf-HFs-A, leaf-HFs-B and leaf-HFs-C. leaf-HFs-A exhibit the best hub-filament morphology, which also have the highest density contrast, the largest mass and the lowest virial ratio. We employed the FILFINDER algorithm to identify and characterize filaments within 185 leaf-HFs-A structures, and fitted the velocity gradients around the intensity peaks. Measurements of velocity gradients provide evidence for gas inflow within these structures, which can serve as a kinematic evidence that these structures are hub-filament structures. The numbers of the associated 21 μm and Hα structures and the peak intensities of 7.7 μm, 21 μm and Hα emissions decrease from leaf-HFs-A to leaf-HFs-C. The spatial separations between the intensity peaks of CO and 21 μm structures of leaf-HFs-A are larger than those of leaf-HFs-C. These evidence indicate that leaf-HFs-A are more evolved than leaf-HFs-C. There may be an evolutionary sequence from leaf-HFs-C to leaf-HFs-A. Currently, leaf-HFs-C lack a distinct gravitational collapse process that would result in a significant density contrast. The density contrast can effectively measure the extent of the gravitational collapse and the depth of the gravitational potential of the structure which, in turn, shapes the hub-filament morphology. Combined with the kinematic analysis presented in previous studies, a picture emerges that molecular gas in spiral galaxies is organized into network structures through the gravitational coupling of multi-scale hub-filament structures. Molecular clouds, acting as knots within these networks, serve as hubs, which are local gravitational centers and the main sites of star formation
    corecore