111,955 research outputs found

    Utilization of information theory in digital data guidance systems Quarterly progress report no. 1, 1 Sep. - 30 Nov. 1965

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    Information theory in improving digital data guidance syste

    A note on non-binary orthogonal codes

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    Construction of orthogonal matrices using integer as elements for nonbinary codin

    Site-directed mutagenesis of the proposed catalytic amino acids of the Sindbis virus capsid protein autoprotease

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    The structural proteins of Sindbis virus are translated as a polyprotein precursor that is cleaved upon translation. The capsid protein is postulated to be a serine protease that releases itself from the N terminus of the nascent polyprotein by autoproteolysis. We have tested the importance in autoproteolysis of His-141, Asp-147, and Ser-215, previously postulated to form the catalytic triad of the protease, and of Asp-163. Several site-specific mutations were constructed at each of these positions, and the release of the capsid protein during translation in a cell-free system was examined. Because proteolysis occurs in cis during translation, the kinetics of release cannot be determined in this system, but the extent of proteolysis can be ascertained. Ser-215 appears to be the catalytic serine of the proteinase. Cys or Thr could substitute inefficiently for Ser-215, but substitution with Ala or Ile led to complete loss of activity. His-141 was also important for proteolysis. Substitution with Ala or Pro led to total loss of activity. Surprisingly, substitution with Arg resulted in complete proteolysis in vitro. Changes at the two Asp residues resulted in complete proteolysis of the substrate in vitro. All mutations that resulted in at least partial cleavage in vitro were incorporated into a full-length clone of Sindbis virus and an attempt was made to recover mutant virus. All changes tested were lethal for the virus except Asp-163 to Asn. Thus, production of infectious virus is either a more sensitive measure of the catalytic rate than the extent of in vitro cleavage, or these residues have necessary functions in addition to their possible role in proteolysis

    Airborne infrared mineral mapping survey of Marysvale, Utah

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    Infrared spectroradiometer survey results from flights over the Marysvale, Utah district show that hydrothermal alteration mineralogy can be mapped using very rapid and effective airborne techniques. The system detects alteration mineral absorption band intensities in the infrared spectral region with high sensitivity. The higher resolution spectral features and high spectral differences characteristic of the various clay and carbonate minerals are also readily identified by the instrument allowing the mineralogy to be mapped as well as the mineralization intensity

    Structure of the Partition Function and Transfer Matrices for the Potts Model in a Magnetic Field on Lattice Strips

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    We determine the general structure of the partition function of the qq-state Potts model in an external magnetic field, Z(G,q,v,w)Z(G,q,v,w) for arbitrary qq, temperature variable vv, and magnetic field variable ww, on cyclic, M\"obius, and free strip graphs GG of the square (sq), triangular (tri), and honeycomb (hc) lattices with width LyL_y and arbitrarily great length LxL_x. For the cyclic case we prove that the partition function has the form Z(Λ,Ly×Lx,q,v,w)=∑d=0Lyc~(d)Tr[(TZ,Λ,Ly,d)m]Z(\Lambda,L_y \times L_x,q,v,w)=\sum_{d=0}^{L_y} \tilde c^{(d)} Tr[(T_{Z,\Lambda,L_y,d})^m], where Λ\Lambda denotes the lattice type, c~(d)\tilde c^{(d)} are specified polynomials of degree dd in qq, TZ,Λ,Ly,dT_{Z,\Lambda,L_y,d} is the corresponding transfer matrix, and m=Lxm=L_x (Lx/2L_x/2) for Λ=sq,tri(hc)\Lambda=sq, tri (hc), respectively. An analogous formula is given for M\"obius strips, while only TZ,Λ,Ly,d=0T_{Z,\Lambda,L_y,d=0} appears for free strips. We exhibit a method for calculating TZ,Λ,Ly,dT_{Z,\Lambda,L_y,d} for arbitrary LyL_y and give illustrative examples. Explicit results for arbitrary LyL_y are presented for TZ,Λ,Ly,dT_{Z,\Lambda,L_y,d} with d=Lyd=L_y and d=Ly−1d=L_y-1. We find very simple formulas for the determinant det(TZ,Λ,Ly,d)det(T_{Z,\Lambda,L_y,d}). We also give results for self-dual cyclic strips of the square lattice.Comment: Reference added to a relevant paper by F. Y. W

    Computer aided design and analysis of gear tooth geometry

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    A simulation method for gear hobbing and shaping of straight and spiral bevel gears is presented. The method is based upon an enveloping theory for gear tooth profile generation. The procedure is applicable in the computer aided design of standard and nonstandard tooth forms. An inverse procedure for finding a conjugate gear tooth profile is presented for arbitrary cutter geometry. The kinematic relations for the tooth surfaces of straight and spiral bevel gears are proposed. The tooth surface equations for these gears are formulated in a manner suitable for their automated numerical development and solution
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