283 research outputs found

    Predictions of structural elements for the binding of Hin recombinase with the hix site of DNA

    Get PDF
    Molecular dynamics simulations were coupled with experimental data from biochemistry and genetics to generate a theoretical structure for the binding domain of Hin recombinase complexed with the hix site of DNA. The theoretical model explains the observed sequence specificity of Hin recombinase and leads to a number of testable predictions concerning altered sequence selectivity for various mutants of protein and DNA. Combining molecular dynamics simulations with constraints based on current knowledge of protein structure leads to a theoretical structure of the binding domain of Hin recombinase with the hix site of DNA. The model offers a mechanistic explanation of the presently known characteristics of Hin and predicts the effects of specific mutations of both protein and DNA. The predictions can be tested by currently feasible experiments that should lead to refinements in and improvements on the current theoretical model. Because current experimental and theoretical methods are all limited to providing only partial information about protein-DNA interactions, we believe that this approach of basing molecular simulations on experimental knowledge and using the results of these simulations to design new, more precise experimental tests will be of general utility. These results provide additional evidence for the generality of the helix-turn-helix motif in DNA recognition and stabilization of proteins on DNA

    What do indigenous communities think of the CSR practices of mining companies?

    Full text link
    This paper examines how one indigenous community in the Western Province of Papua New Guinea (PNG) views the social responsibility initiatives of OK Tedi Mining Ltd (OTML). This mining operation has been controversial since its inception, and various operators of the mine have sought to engage the community and to undertake a number of CSR-related projects. Insights gained from four focus groups amongst the Ok Tedi River indigenous communities show that while some members of the community are satisfied with the company’s efforts at the macro level, many have reservations about the effectiveness of the programs at the micro level on the village and family unit. The implementation of CSR activities are slow and in many instances do not effectively address stakeholder concerns

    An Unusual Hydrogen Migration/C−H Activation Reaction with Group 3 Metals

    Get PDF
    A novel hydrogen migration from the phenyl ring to the pyridine ring of an yttrium pyridyl complex supported by a 1,1′-ferrocene diamide ligand is reported. Density functional theory calculations were instrumental in probing the mechanism for this transformation

    Defined by wine : a study of sacramentalism in George Herbertʾs poetry

    Get PDF
    This dissertation proposes that George Herbertʾs poetry may profitably be understood as a sacramental means by which the divine is made present in temporal existence. In order to support this claim, the relation between sacramental symbolism and literary symbolism, particularly Herbertʾs, is examined from a number of perspectives. The symbolic meanings suggested by Herbertʾs title (The Temple), and their relation to sacramentalism are considered in the opening chapter. This includes a consideration of some of the background to the analogical thinking prevalent in both the seventeenth-century and Herbert. It is followed in the second chapter by an examination of some of the modern theories about how literary symbolism may relate to sacramental symbolism, a discussion which is followed by a consideration of this dissertation's argument in relation to modern scholarship. The chapter ends with a reading of ʺThe Flowerʺ. The third chapter discusses the poet's attempt to imitate the divine by ʺcopyingʺ both Scripture and Nature, and this includes a consideration of the allegorical and hieroglyphic modes of thought prevalent in the poems. The concern with imitation encourages an examination of the poet's frequent invitation for God actually to assume the poet's role, and this is the subject of the fourth chapter. The argument suggests that the poet's attempt to ʺsacrificeʺ his own writing may be seen in his concern with corporate imagery and corporate (impersonal) structures. The five ʺAfflictionʺ poems are examined as examples of the first, while structures such as synecdoche and metonymy are examined as examples of the second. The final chapter considers aspects of narrative time in the poems, particularly the sense often evoked of the eternal being imminent in the present. This involves a consideration of both liturgical imagery, and what may be called liturgical structures as they can be seen to operate in the poems. Particular examples of the latter are the relation between the liturgical anamnesis and the poems, as well as certain narrative structures that may be called ʺachronisticʺ

    Versions of confinement: Melville's bodies and the psychology of conquest

    Get PDF
    This thesis explores aspects of Melville’s presentation of both the whale and the human bodies in Moby-Dick and human bodies in other important novels. It argues that Melville uses his presentation of bodies to explore some of the versions of confinement those bodies experience, and by doing so, analyses the psychology which subtends that confinement. Throughout Melville’s works bodies are confined, both within literal spatial limits and by the psychology which creates and/or accepts these spatial limits. The thesis argues that perhaps the most important version of bodily confinement Melville addresses is the impulse to conquer bodies, both that of the other and one’s own. It adopts a largely psychoanalytic approach to interpreting bodies and their impulse to conquer, so that the body is seen to figure both in its actions and its external appearance the operations of the inner psyche. The figure of the body is equally prevalent in Melville’s exploration of nationalist conquest, where, as with Manifest Destiny and antebellum expansionism, the psychological and physical lack experienced by characters can be read as motivating factors in the ideology of conquest. A final important strand of the thesis is its argument in favour of a gradual shift in Melville’s interpretation of the value and possibility of genuine communion between human beings and between humans and the whale. One may read Typee as an attempt by Melville to explore the possibility of a this-worldly utopia in which human beings can return to a version of primitive interconnectedness. This exploration may be seen to be extended in Moby-Dick, particularly in Ishmael’s attempts to find communion with others and in some moments of encounter with the whales. The thesis uses phenomenology as a theory to interpret what Melville is trying to suggest in these moments of encounter. However, it argues, finally, that such encounter, or ‘intersubjectivity’ is eventually jettisoned, especially in the works after Moby-Dick. By the end of Melville’s life and work, any hope of an intersubjective utopia he may have harboured as a younger man have been removed in favour of a refusal actually to assert any final ‘truth’ about social, political or even religious experience. Billy Budd, his last body, is hanged, and his final word is silence

    Reaction of Group III Biheterocyclic Complexes

    Get PDF
    Group III alkyl complexes supported by a ferrocene diamide ligand (1,1′-fc(NSitBuMe_2)_2) have been found to be reactive toward aromatic N-heterocycles such as 1-methylimidazole and pyridines. These reactions were investigated experimentally and computationally. An initial C−H activation event is followed by a coupling reaction to form biheterocyclic complexes, in which one of the rings is dearomatized. In the case of 1-methylimidazole, the biheterocyclic compound could not be isolated and further led to an imidazole ring-opened product; in the case of pyridines, it transformed into an isomer with extended conjugation of double bonds. Mechanisms for both reactions are proposed on the basis of experimental and computational results. DFT calculations were also used to show that an energetically accessible pathway for the ring-opening of pyridines exists

    No silver bullet: a Delphi study of emergent leadership in Missouri high-performing, high-poverty schools

    Get PDF
    Title from PDF of title page (University of Missouri--Columbia, viewed on May 25, 2010).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Dissertation advisor: Dr. Peggy Placier.Vita.Ph. D. University of Missouri--Columbia 2010.This dissertation studied how principals allow leadership to emerge in high performing, high poverty schools (HP2S) in Missouri. Complexity science, self-organization, and emergence are keys to understanding how leadership can impact student performance in low-performing schools. A Trend Model Delphi implementing lead-user strategy yielded mixed data revealing the leadership practices of 6 expert principals in Missouri HP2S. Results indicated the Domains and Stages of Emergence can be a useful framework for categorizing interactions in HP2S. The domains of Identity, Information, and Relationships overlap to open a novel space for stages to function and allow punctuated renewal. The stages of Networking, Commitment to a Community of Practice, and Strengthening and Diversifying Connections help explain the emergence of a complex system capable of multi-dimensional learning across multiple dimensions of time and in an infinite number of spaces including the space for novelty for the emergence of leadership and innovative practice. Out of 9 intersections of domain and stage, 3 produce emergent properties: 3rd order change, Critical Praxis, High-capacity building. In short, leadership is something that is shared with and emerges from many diverse agents interacting with the principal during processes designed to achieve HP2S. Findings present principals with order parameters they can feed into a low-performing school to facilitate transition to high performing. Other areas for further study include replication across geographically and demographically diverse areas of the state, nation, and globe to fully develop a model of emergent leadership as well as high-quality professional development opportunities.Includes bibliographical reference

    An et al. Reply

    Get PDF
    Our Letter reported high-resolution transmission electron microscopy on commercial quality boron showing that ∼2=3 of the grains exhibit smooth microstructure, leading to an x-ray diffraction pattern of well-known beta boron [1]. The other 1=3 grains exhibit a uniform zigzag pattern that extends across the entire grain and exhibits a very regular twinlike symmetry on every other lattice plane. This second phase gives diffraction patterns that are different from beta

    New Ground-State Crystal Structure of Elemental Boron

    Get PDF
    Elemental boron exhibits many polymorphs in nature based mostly on an icosahedral shell motif, involving stabilization of 13 strong multicenter intraicosahedral bonds. It is commonly accepted that the most thermodynamic stable structure of elemental boron at atmospheric pressure is the β rhombohedral boron (β−B). Surprisingly, using high-resolution transmission electron microscopy, we found that pure boron powder contains grains of two different types, the previously identified β−B containing a number of randomly spaced twins and what appears to be a fully transformed twinlike structure. This fully transformed structure, denoted here as τ−B, is based on the Cmcm orthorhombic space group. Quantum mechanics predicts that the newly identified τ−B structure is 13.8  meV/B more stable than β−B. The τ−B structure allows 6% more charge transfer from B_(57) units to nearby B_(12) units, making the net charge 6% closer to the ideal expected from Wade’s rules. Thus, we predict the τ−B structure to be the ground state structure for elemental boron at atmospheric pressure
    • …
    corecore