3,883 research outputs found

    Defective λ interferon production in leprosy reversal with antigen and interleukin 2

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    Indeterminacy by underspecification

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    We examine the formal encoding of feature indeterminacy, focussing on case indeterminacy as an exemplar of the phenomenon. Forms that are indeterminately specified for the value of a feature can simultaneously satisfy conflicting requirements on that feature and thus are a challenge to constraint-based formalisms which model the compatibility of information carried by linguistic items by combining or integrating that information. Much previous work in constraint-based formalisms has sought to provide an analysis of feature indeterminacy by departing in some way from ‘vanilla’ assumptions either about feature representations or about how compatibility is checked by integrating information from various sources. In the present contribution we argue instead that a solution to the range of issues posed by feature indeterminacy can be provided in a ‘vanilla’ feature-based approach which is formally simple, does not postulate special structures or objects in the representation of case or other indeterminate features, and requires no special provision for the analysis of coordination. We view the value of an indeterminate feature such as case as a complex and possibly underspecified feature structure. Our approach correctly allows for incremental and monotonic refinement of case requirements in particular contexts. It uses only atomic boolean-valued features and requires no special mechanisms or additional assumptions in the treatment of coordination or other phenomena to handle indeterminacy. Our account covers the behaviour of both indeterminate arguments and indeterminate predicates, that is, predicates placing indeterminate requirements on their arguments.</jats:p

    The Languages Spoken in the Water Body (or the Biological Role of Cyanobacterial Toxins)

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    Although intensification of toxic cyanobacterial blooms over the last decade is a matter of growing concern due to bloom impact on water quality, the biological role of most of the toxins produced is not known. In this critical review we focus primarily on the biological role of two toxins, microcystins and cylindrospermopsin, in inter- and intra-species communication and in nutrient acquisition. We examine the experimental evidence supporting some of the dogmas in the field and raise several open questions to be dealt with in future research. We do not discuss the health and environmental implications of toxin presence in the water body

    A computational scheme to evaluate Hamaker constants of molecules with practical size and anisotropy

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    We propose a computational scheme to evaluate Hamaker constants, AA, of molecules with practical sizes and anisotropies. Upon the increasing feasibility of diffusion Monte Carlo (DMC) methods to evaluate binding curves for such molecules to extract the constants, we discussed how to treat the averaging over anisotropy and how to correct the bias due to the non-additivity. We have developed a computational procedure for dealing with the anisotropy and reducing statistical errors and biases in DMC valuations, based on possible validations on predicted AA. We applied the scheme to cyclohexasilane molecule, Si6_6H12_{12}, used in 'printed electronics' fabrications, getting A105±2A \sim 105 \pm 2 [zJ], being in plausible range supported even by other possible extrapolations. The scheme provided here would open a way to use handy {\it ab initio} evaluations to predict wettabilities as in the form of materials informatics over broader molecules.Comment: The manuscript was revised according to review comment

    Does Corporate Lobbying Benefit Society?

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    Lobbying, defined as an effort to influence policy through strategic communication, has grown dramatically in recent years. This paper presents three viewpoints regarding the societal impact of corporate lobbying on society: one perspective argues that lobbying will be primarily beneficial, an alternative perspective contests this viewpoint and suggests that it is generally harmful, and the third argues that the impact is contingent on a number of factors. Proponents of lobbying argue that it is a vital mechanism to transmit valuable information and expertise to policymakers, leading to substantive legislative solutions for resolving complex societal issues. Critics, on the other hand, point out that business dominates lobbying and can leverage vast resources to push biased information in the pursuit of narrow profit-oriented interests. There are three key axes of contention between these three perspectives; first, concerning the definition of lobbying and its relation to corporate power; second, its relationship to democratic processes; and third, regarding alignment or conflict between societal and business interests. The paper examines these issues and draws implications for future research

    The evolving doublecortin (DCX) superfamily

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    BACKGROUND: Doublecortin (DCX) domains serve as protein-interaction platforms. Mutations in members of this protein superfamily are linked to several genetic diseases. Mutations in the human DCX gene result in abnormal neuronal migration, epilepsy, and mental retardation; mutations in RP1 are associated with a form of inherited blindness, and DCDC2 has been associated with dyslectic reading disabilities. RESULTS: The DCX-repeat gene family is composed of eleven paralogs in human and in mouse. Its evolution was followed across vertebrates, invertebrates, and was traced to unicellular organisms, thus enabling following evolutionary additions and losses of genes or domains. The N-terminal and C-terminal DCX domains have undergone sub-specialization and divergence. Developmental in situ hybridization data for nine genes was generated. In addition, a novel co-expression analysis for most human and mouse DCX superfamily-genes was performed using high-throughput expression data extracted from Unigene. We performed an in-depth study of a complete gene superfamily using several complimentary methods. CONCLUSION: This study reveals the existence and conservation of multiple members of the DCX superfamily in different species. Sequence analysis combined with expression analysis is likely to be a useful tool to predict correlations between human disease and mouse models. The sub-specialization of some members due to restricted expression patterns and sequence divergence may explain the successful addition of genes to this family throughout evolution

    Computational Strategy for Graphene: Insight from Odd Electrons Correlation

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    The correlation of odd electrons in graphene turns out to be significant so that the species should be attributed to correlated ones. This finding profoundly influences the computational strategy addressing it to multireference computational schemes. Owing to serious problems related to the schemes realization, a compromise can be suggested by using single-determinant approaches based on either Hartree-Fock or Density-Functional theory in the form of unrestricted open-shell presentation. Both computational schemes enable to fix the electron correlation, while only the Hartree-Fock theory suggests a set of quantities to be calculated that can quantitatively characterize the electron correlation and be used for a quantitative description of such graphene properties as magnetism, chemical reactivity, and mechanical response. The paper presents concepts and algorithms of the unrestricted Hartree-Fock theory applied for the consideration of magnetic properties of nanographenes, their chemical modification by the example of stepwise hydrogenation, as well as a possible governing the electron correlation by the carbon skeleton deformation.Comment: 17 pages, 11 figures, 3 table

    Simple hydrogenic estimates for the exchange and correlation energies of atoms and atomic ions, with implications for density functional theory

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    Exact density functionals for the exchange and correlation energies are approximated in practical calculations for the ground-state electronic structure of a many-electron system. An important exact constraint for the construction of approximations is to recover the correct non-relativistic large-ZZ expansions for the corresponding energies of neutral atoms with atomic number ZZ and electron number N=ZN=Z, which are correct to leading order (0.221Z5/3-0.221 Z^{5/3} and 0.021ZlnZ-0.021 Z \ln Z respectively) even in the lowest-rung or local density approximation. We find that hydrogenic densities lead to Ex(N,Z)0.354N2/3ZE_x(N,Z) \approx -0.354 N^{2/3} Z (as known before only for ZN1Z \gg N \gg 1) and Ec0.02NlnNE_c \approx -0.02 N \ln N. These asymptotic estimates are most correct for atomic ions with large NN and ZNZ \gg N, but we find that they are qualitatively and semi-quantitatively correct even for small NN and for NZN \approx Z. The large-NN asymptotic behavior of the energy is pre-figured in small-NN atoms and atomic ions, supporting the argument that widely-predictive approximate density functionals should be designed to recover the correct asymptotics. It is shown that the exact Kohn-Sham correlation energy, when calculated from the pure ground-state wavefunction, should have no contribution proportional to ZZ in the ZZ\to \infty limit for any fixed NN.Comment: This work has been accepted for publication at the Journal of Chemical Physics. Revisions: new Appendix A (former Appendix A is now Appendix B) discussing exact Kohn-Sham perturbation series for Ec. Added material discussing the Becke 1988 functional. More discussion of non-empirical functionals' recovery of the asymptotic series, and their accuracy in predicting atomic/molecular energie

    Defective axonal transport in motor neuron disease

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    Several recent studies have highlighted the role of axonal transport in the pathogenesis of motor neuron diseases. Mutations in genes that control microtubule regulation and dynamics have been shown to cause motor neuron degeneration in mice and in a form of human motor neuron disease. In addition, mutations in the molecular motors dynein and kinesins and several proteins associated with the membranes of intracellular vesicles that undergo transport cause motor neuron degeneration in humans and mice. Paradoxically, evidence from studies on the legs at odd angles (Loa) mouse and a transgenic mouse model for human motor neuron disease suggest that partial limitation of the function of dynein may in fact lead to improved axonal transport in the transgenic mouse, leading to delayed disease onset and increased life span
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