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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 197 (1988), S. 476-489 
    ISSN: 1432-041X
    Keywords: Cell surface patterns ; Double mutant analysis ; Ciliate development ; Tetrahymena thermophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An analysis of bcd, janA; bcd, janB; and bcd, janC double-mutant phenotypes in Tetrahymena thermophila has allowed us to examine patterning processes affected by two different classes of mutations. bcd brings about a broadening of the oral and contractile vacuole pore domains in the ciliate cortex, while the janus mutations generate a mirror-image duplication of the ventral cortical pattern. We observed both bcd and janus characteristics expressed in the double mutants, as well as features unique to the double-mutant. Temperature-shift experiments employing the temperature-sensitive janB mutation in a double-mutant (bcd, janB) combination allowed us to observe the changes in pattern as a mirror-image geometry was brought into expression and subsequently removed within the bcd, janB double homozygote. These experiments suggest that there are multiple pattern-mechanisms at work with differing kinetics of expression in the ciliate cortex. We discuss how the bcd mutation could influance expression of the janus mutations in light of a model previously proposed to account for the janus phenotype.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 194 (1984), S. 107-120 
    ISSN: 1432-041X
    Keywords: Cellular asymmetry reversal ; Cell surface patterns ; Mutations affecting patterns ; Ciliate development ; Tetrahymena thermophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of the oral apparatus (OA) and of neighboring ciliary structures ofTetrahymena thermophila was analyzed in cells homozygous for ajanus (jan A) mutation plus a recessiveenhancer of janA (eja). Such cells frequently possess two OAs located on opposite sides of the cell, a primary (1°) OA previously reported to be normal, and a secondary (2°) OA previously reported to express a mirror-reversal of right-left asymmetry. This study confirms the reality of a reversal in the gross orientation of membranelles in most developing 2° OAs. It also shows that there is a reversal of asymmetry in the pattern of resorption of basal bodies of ciliary rows adjacent to the 2° OA, and in the arrangement of basal-body couplets making up the portion of the apical “crown” of the cell situated close to the 2° OA. However, the locations at which membranelles of the 2° OA become modified during late phases of oral development remain normal, so that membranelles of 2° OAs are superimposable on those of 1° OAs. In addition, the membranelles of 2° OAs frequently undergo a rotation during the final phases of oral development, so that even their spatial orientation becomes normal. This mixture of reversed and normal features can be accounted for by postulating a superimposition of a reversed largescale asymmetry on a normal local asymmetry of ciliary units. This postulate predicts that no single mutation can bring about a complete mirror-image reversal of ciliary patterns. 1° OAs appear normal by light microscopy. However, detailed analysis of SEM, preparations of isolated 1° OAs indicate subtle abnormalities of basal body arrangement in some of these OAs.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 196 (1987), S. 421-433 
    ISSN: 1432-041X
    Keywords: Cell surface patterns ; Mutations affecting patterns ; Ciliate development ; Tetrahymena thermophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A single-gene recessive mutation, bcd (broadened cortical domains), of Tetrahymena thermophila is characterized by a variable broadening of the spatial domains within which cortical organelles, including both the contractile vacuole pores (CVP) and oral apparatus (OA), are formed. The phenotype is not temperature-sensitive. During the development of the organelles of the mutant prior to cell division, extra CVPs and extra oral primordia (OP) appear near ciliary rows adjacent to the rows at which these structures normally form. In the later stages of development, some, but not all, of these extra structures are resorbed, or in the case of the oral domain, multiple adjacent OPs may be completely or partially integrated into a single enlarged OA. When multiple OAs persist, one or more of these may display a reversed orientation reminiscent of those encountered in janus mutants. However, unlike janus, bcd cells do not express any sign of a mirror-image global organization. Our results can best be accounted for by postulating that the bcd mutation affects some common determinant of the widths of both CVP and OA domains. Studies are in progress which explore the relationship between this width-determining mechanism(s) and the mechanism(s) determining the location of cortical organelles around the cell circumference.
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 17 (1981), S. 43-52 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A parametric element is formulated which enables the economic modelling of ‘infinite domain’ type problmes. A typical problem is an opening in a stress field in an infinite medium, either in two or three dimensions. The strategy is to model around the opening with two or three layers of conventional isoparametric finite elements and surround these with a single layer of ‘infinite domain’ elements.Several sample problems has been analysed for circular, square and spherical openings in infinite media, and the results compared with either theoretical or boundary element solutions which include the ‘infinite’ boundary in their solution technique.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 21 (1985), S. 1381-1390 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A numerical scheme has been constructed to simulate the imposition of a step in heat transfer at the surface of a multi-layered substrate. The numerical simulation of this process is carried out by applying an extended version of the Keller Box-Scheme to multi-layered diffusion problems. Numerical calculations show that accurate choice of length and time-scales is critical in determining the behaviour of the heat flow through the substrate. Thus, the results from the numerical simulations are of value to the experimentalist, particularly in determining the accurate shape of the response curves which enable experimental apparatus to be designed effectively. The proposed scheme yields heat fluxes as accurately as temperatures, and can be easily adapted to other related applications.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 9 (1975), S. 765-773 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The paper examines two triangular finite elements used in plate bending analyses for which Lagrange multiplier techniques have been used to set up the necessary equations for the solution. These equations involve either equilibrium of the system or the inter-element compatibility. Starting from only the notions of equilibrium and continuity as used in the analyses of redundant structures, the paper proceeds to solutions of the same problems. It is found that end results are the same when the equations obtained from the minimization techniques are reduced by Gauss-elimination in partitioned from.
    Additional Material: 4 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 10 (1976), S. 954-957 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 49-67 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A flat shell element which utilizes the linear strain triangle (LST) for membrane representation and a plate-bending element labelled DKL (for discrete Kirchhoff element with Loof nodes) previously derived by the authors in Reference 1, is presented. This element is free from the deficiencies of displacement incompatibility, singularity with coplanar elements, inability to model intersections and low order membrane strain representation, which are associated with existing faceted shell elements. The results of the numerical examples indicate that the convergence characteristics of this element are good.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 20 (1984), S. 1175-1175 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 3761-3774 
    ISSN: 0029-5981
    Keywords: history ; finite elements ; structural mechanics ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper presents summaries of the works of several authors associated with the invention of the analysis technique now referred to as the finite element method. It stresses the notion of first development from which subsequent ideas evolved and gives what is believed to be an accurate record of the historical sequence of published papers in the international literature.
    Additional Material: 7 Ill.
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