256 research outputs found

    Smart Knowledge Capture for Developing Adaptive Management Systems

    Get PDF
    In this paper we describe how a welldesigned Spatial Decision Support System (SDSS) may facilitate initial (immediate) decision making, while establishing a robust foundation and framework for improving effectiveness over time as new data and knowledge becomes available. \u27Smart Knowledge Capture\u27 is a set of methods for rapidly developing a strong SDSS for adaptive management. We review some of the MIS tools used in Smart Knowledge Capture: multicriteria decision analysis (MCDA) tools, online surveys, online knowledge portals, ontology systems, and describe the architecture of an SDSS that stores and utilizes this knowledge. We illustrate these concepts using our recent work supporting the development of a revised desert tortoise recovery plan

    Correlation effects in ionic crystals: I. The cohesive energy of MgO

    Full text link
    High-level quantum-chemical calculations, using the coupled-cluster approach and extended one-particle basis sets, have been performed for (Mg2+)n (O2-)m clusters embedded in a Madelung potential. The results of these calculations are used for setting up an incremental expansion for the correlation energy of bulk MgO. This way, 96% of the experimental cohesive energy of the MgO crystal is recovered. It is shown that only 60% of the correlation contribution to the cohesive energy is of intra-ionic origin, the remaining part being caused by van der Waals-like inter-ionic excitations.Comment: LaTeX, 20 pages, no figure

    Analyzing and enhancing OSKI for sparse matrix-vector multiplication

    Get PDF
    Sparse matrix-vector multiplication (SpMxV) is a kernel operation widely used in iterative linear solvers. The same sparse matrix is multiplied by a dense vector repeatedly in these solvers. Matrices with irregular sparsity patterns make it difficult to utilize cache locality effectively in SpMxV computations. In this work, we investigate single- and multiple-SpMxV frameworks for exploiting cache locality in SpMxV computations. For the single-SpMxV framework, we propose two cache-size-aware top-down row/column-reordering methods based on 1D and 2D sparse matrix partitioning by utilizing the column-net and enhancing the row-column-net hypergraph models of sparse matrices. The multiple-SpMxV framework depends on splitting a given matrix into a sum of multiple nonzero-disjoint matrices so that the SpMxV operation is performed as a sequence of multiple input- and output-dependent SpMxV operations. For an effective matrix splitting required in this framework, we propose a cache-size-aware top-down approach based on 2D sparse matrix partitioning by utilizing the row-column-net hypergraph model. The primary objective in all of the three methods is to maximize the exploitation of temporal locality. We evaluate the validity of our models and methods on a wide range of sparse matrices by performing actual runs through using OSKI. Experimental results show that proposed methods and models outperform state-of-the-art schemes.Comment: arXiv admin note: substantial text overlap with arXiv:1202.385

    Raman scattering in C_{60} and C_{48}N_{12} aza-fullerene: First-principles study

    Full text link
    We carry out large scale {\sl ab initio} calculations of Raman scattering activities and Raman-active frequencies (RAFs) in C48N12{\rm C}_{48}{\rm N}_{12} aza-fullerene. The results are compared with those of C60{\rm C}_{60}. Twenty-nine non-degenerate polarized and 29 doubly-degenerate unpolarized RAFs are predicted for C48N12{\rm C}_{48}{\rm N}_{12}. The RAF of the strongest Raman signal in the low- and high-frequency regions and the lowest and highest RAFs for C48N12{\rm C}_{48}{\rm N}_{12} are almost the same as those of C60{\rm C}_{60}. The study of C60{\rm C}_{60} reveals the importance of electron correlations and the choice of basis sets in the {\sl ab initio} calculations. Our best calculated results for C60{\rm C}_{60} with the B3LYP hybrid density functional theory are in excellent agreement with experiment and demonstrate the desirable efficiency and accuracy of this theory for obtaining quantitative information on the vibrational properties of these molecules.Comment: submitted to Phys.Rev.

    Electron affinities of the first- and second- row atoms: benchmark ab initio and density functional calculations

    Full text link
    A benchmark ab initio and density functional (DFT) study has been carried out on the electron affinities of the first- and second-row atoms. The ab initio study involves basis sets of spdfghspdfgh and spdfghispdfghi quality, extrapolations to the 1-particle basis set limit, and a combination of the CCSD(T), CCSDT, and full CI electron correlation methods. Scalar relativistic and spin-orbit coupling effects were taken into account. On average, the best ab initio results agree to better than 0.001 eV with the most recent experimental results. Correcting for imperfections in the CCSD(T) method improves the mean absolute error by an order of magnitude, while for accurate results on the second-row atoms inclusion of relativistic corrections is essential. The latter are significantly overestimated at the SCF level; for accurate spin-orbit splitting constants of second-row atoms inclusion of (2s,2p) correlation is essential. In the DFT calculations it is found that results for the 1st-row atoms are very sensitive to the exchange functional, while those for second-row atoms are rather more sensitive to the correlation functional. While the LYP correlation functional works best for first-row atoms, its PW91 counterpart appears to be preferable for second-row atoms. Among ``pure DFT'' (nonhybrid) functionals, G96PW91 (Gill 1996 exchange combined with Perdew-Wang 1991 correlation) puts in the best overall performance. The best results overall are obtained with the 1-parameter hybrid modified Perdew-Wang (mPW1) exchange functionals of Adamo and Barone [J. Chem. Phys. {\bf 108}, 664 (1998)], with mPW1LYP yielding the best results for first-row, and mPW1PW91 for second-row atoms. Indications exist that a hybrid of the type aa mPW1LYP + (1−a)(1-a) mPW1PW91 yields better results than either of the constituent functionals.Comment: Phys. Rev. A, in press (revised version, review of issues concerning DFT and electron affinities added

    A mathematical and computational review of Hartree-Fock SCF methods in Quantum Chemistry

    Get PDF
    We present here a review of the fundamental topics of Hartree-Fock theory in Quantum Chemistry. From the molecular Hamiltonian, using and discussing the Born-Oppenheimer approximation, we arrive to the Hartree and Hartree-Fock equations for the electronic problem. Special emphasis is placed in the most relevant mathematical aspects of the theoretical derivation of the final equations, as well as in the results regarding the existence and uniqueness of their solutions. All Hartree-Fock versions with different spin restrictions are systematically extracted from the general case, thus providing a unifying framework. Then, the discretization of the one-electron orbitals space is reviewed and the Roothaan-Hall formalism introduced. This leads to a exposition of the basic underlying concepts related to the construction and selection of Gaussian basis sets, focusing in algorithmic efficiency issues. Finally, we close the review with a section in which the most relevant modern developments (specially those related to the design of linear-scaling methods) are commented and linked to the issues discussed. The whole work is intentionally introductory and rather self-contained, so that it may be useful for non experts that aim to use quantum chemical methods in interdisciplinary applications. Moreover, much material that is found scattered in the literature has been put together here to facilitate comprehension and to serve as a handy reference.Comment: 64 pages, 3 figures, tMPH2e.cls style file, doublesp, mathbbol and subeqn package

    Anthropometric, biochemical, dietary, morbidity and well-being assessments in women and children in Indonesia, India and Senegal : A UKRI GCRF Action Against Stunting Hub protocol paper

    Get PDF
    HD-K and EF were responsible for the overall design, training and overseeing implementation of the research. UF, MKH, BK, BF, RM, RPullakhandam, RPalika, TD, SFR, SD, RPradeilles, SA, AW, JPW, PH and CH were involved in its design. UF, MKH, BK, BF, DY, DS, NLZ, TCA, RM, RPullakhandam, RPalika, TD, SFR, SKB KS, DPP, DY, SD, PL-S, BD, PM, SF, ID, AD, TDVI, FT, AD, SS, BMK and DTT implemented the research. HD-K and EF wrote the manuscript. All authors read, provided comments on and approved the final version of the manuscript.Peer reviewe

    An integrative review exploring decision-making factors influencing mental health nurses in the use of restraint

    Get PDF
    Introduction: While mechanical and manual restraint as an institutional method of control within mental health settings may be perceived to seem necessary at times, there is emergent literature highlighting the potential counter-therapeutic impact of this practice for patients as well as staff. Nurses are the professional group who are most likely to use mechanical and manual restraint methods within mental health settings. In-depth insights to understand what factors influence nurses’ decision-making related to restraint use are therefore warranted. Aim: To explore what influences mental health nurses’ decision-making in the use of restraint. Method: An integrative review using Cooper’s framework was undertaken. Results: Eight emerging themes were identified: ‘safety for all’, ‘restraint as a necessary intervention’, ‘restraint as a last resort’, ‘role conflict’, ‘maintaining control’, ‘staff composition’, ‘knowledge and perception of patient behaviours’, and ‘psychological impact’. These themes highlight how mental health nurses’ decision-making is influenced by ethical and safety responsibilities, as well as, interpersonal and staff-related factors. Conclusion: Research to further understand the experience and actualization of ‘last resort’ in the use of restraint and to provide strategies to prevent restraint use in mental health settings are needed
    • 

    corecore