8,259 research outputs found

    Curvature terms in D-brane actions and their M-theory origin

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    We derive the complete (curvature)2(curvature)^2 terms of effective D-brane actions, for arbitrary ambient geometries and world-volume embeddings, at lowest order (disk-level) in the string-loop expansion. These terms reproduce the o(α2)o(\alpha'^2) corrections to string scattering amplitudes, and are consistent with duality conjectures. In the particular case of the D3-brane with trivial normal bundle, considerations of SL(2,Z)SL(2,\mathbb{Z}) invariance lead to a complete sum of D-instanton corrections for both the parity-conserving and the parity-violating parts of the effective action. These corrections are required for the cancellation of the modular anomalies of massless modes, and are consistent with the absence of chiral anomalies in the intersection domain of pairs of D-branes. We also show that the parity-conserving part of the non-perturbative R^2 action follows from a one-loop quantum calculation in the six-dimensional world-volume of the M5-brane compactified on a two-torus.Comment: tex file, 31 pages, uses harvmac. Some rewriting of section 2, conclusions and appendix B, in particular in what concerns the discussion of seven-branes in the conclusions and the structure of α2\alpha'^2 terms in appendix B. Other minor corrections plus added reference

    CFD Mixing Analysis of Jets Injected from Straight and Slanted Slots into Confined Crossflow in Rectangular Ducts

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    A CFD study was performed to analyze the mixing potential of opposed rows of staggered jets injected into confined crossflow in a rectangular duct. Three jet configurations were numerically tested: (1) straight (0 deg) slots; (2) perpendicular slanted (45 deg) slots angled in opposite directions on top and bottom walls; and (3) parallel slanted (45 deg) slots angled in the same direction on top and bottom walls. All three configurations were tested at slot spacing-to-duct height ratios (S/H) of 0.5, 0.75, and 1.0; a jet-to-mainstream momentum flux ratio (J) of 100; and a jet-to-mainstream mass flow ratio of 0.383. Each configuration had its best mixing performance at S/H of 0.75. Asymmetric flow patterns were expected and predicted for all slanted slot configurations. The parallel slanted slot configuration was the best overall configuration at x/H of 1.0 for S/H of 0.75

    Handbook for Learning-centred evaluation of Computer-facilitated learning projects in higher education

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    This handbook supports a project funded by the Australian Government Committee for University Teaching and Staff Development (CUTSD). The amended project title is “Staff Development in Evaluation of Technology-based Teaching Development Projects: An Action Inquiry Approach”. The project is hosted by Murdoch University on behalf of the Australasian Society for Computers in Learning in Tertiary Education (ASCILITE), as a consortium of 11 universities. The rationale of the project is to guide a group of university staff through the evaluation of a Computer-facilitated Learning (CFL1) project by a process of action inquiry and mentoring, supported by the practical and theoretical material contained in this handbook

    Educación. Discurso del Sr. Wilfred C. Bain

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    CFD mixing analysis of axially opposed rows of jets injected into confined crossflow

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    A computational fluid dynamics (CFD) parametric study was performed to analyze axially opposed rows of jets mixing with crossflow in a rectangular duct. Isothermal analysis was conducted to determine the influence of lateral geometric arrangement on mixing. Two lateral arrangements were analyzed: (1) inline (jets' centerlines aligned with each other on top and bottom walls), and (2) staggered (jets' centerlines offset with each other on top and bottom walls). For a jet-to-mainstream mass flow ratio (MR) of 2.0, design parameters were systematically varied for jet-to-mainstream momentum-flux ratios (J) between 16 and 64 and orifice spacing-to-duct height ratios (S/H) between 0.125 and 1.5. Comparisons were made between geometries optimized for S/H at a specified J. Inline configurations had a unique spacing for best mixing at a specified J. In contrast, staggered configurations had two 'good mixing' spacings for each J, one corresponding to optimum inline spacing and the other corresponding to optimum non-impinging jet spacing. The inline configurations, due to their smaller orifice size at optimum S/H, produced better initial mixing characteristics. At downstream locations (e.g. x/H of 1.5), the optimum non-impinging staggered configuration produced better mixing than the optimum inline configuration for J of 64; the opposite results were observed for J of 16. Increasing J resulted in better mixing characteristics if each configuration was optimized with respect to orifice spacing. Mixing performance was shown to be similar to results from previous dilution jet mixing investigations (MR less than 0.5)

    Dynamic soil clays

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    Exploring the challenges of single mothers in the Philippines: Empowerment as diaconal task of Evangelical church in the Philippines.

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    Single mothers are in need, discriminated against and marginalized in the Philippines. The issues of gender inequality affect the life of single mothers globally. In this master thesis I reflect upon and discuss the research question: “What are the challenges of single motherhood in the Philippines? And how does the Evangelical church meet the needs and empower single mothers?”. The research explores the challenges and experiences of a single motherhood in the Philippines in the extended societal context they live within and looking at the overview of how the church can be a vehicle in empowering these women. Qualitative interview was used in this study. The participant consisted of 4 single mothers and 1 local church leader. Data collection took place using open-ended interviews. Three relevant theories have been employed in this master thesis- perspectives of gender, ecclesiology and the theory of empowerment as diakonia which utilized to answer and explore my research question. The interviews with the single mothers reveal that they live under challenging conditions. The cultural norms and practices have seen to be continually discriminating and undergird inequalities to the daily life journey of the single mothers in the Philippines. The study reveals that the paternalistic and discriminatory practices influenced by the society are existing within the church, deterring the church to fully meet the needs of the single mothers. The study reveals that the church has primarily been working through traditional ways (e.g. preaching) as responding to the needs of the single mothers in the Philippines. The study found out that there is no collaboration between the church and the public states in response to the needs of single mothers. The church as diaconal agent is called to respond to the human suffering, injustice, care for creation; fostering empowerment to every individual, in family and in communities. Empowering single mothers might be best fulfilled and meet the needs of the single mothers if the civic society and church are both collaborating between programs and initiatives

    Cu-Au type orderings in the staggered quadrupolar region of the fcc Blume Emery Griffiths model

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    The spin-1 Ising (BEG) model has been simulated using a cellular automaton (CA) algorithm improved from the Creutz cellular automaton (CCA) for a face-centered cubic (fcc) lattice. The ground state diagram (kk, dd) of the fcc BEG model has ferromagnetic (FF), quadrupolar (QQ) and staggered quadrupolar (SQSQ) ordering regions. The simulations have been made in the staggered quadrupolar region for the parameter values in the intervals 24d=D/J<0 -24\leq d=D/J<0 and 3k=K/J0-3\leq k=K/J\leq 0 . The phase diagrams on the (kTC/J kT_{C}/J, dd) and the (kTC/JkT_{C}/J, kk) planes have been obtained through k=3 k=-3 and d=4d=-4 lines, respectively. The staggered quadrupolar ordering region separates into five ordering regions (A3B(a)A_{3}B(a), A3B(f)A_{3}B(f), ABAB (type-I), ABAB(type-II) and AB3(f)AB_{3}(f)) which have the different stoichiometric Cu-Au type structures.Comment: 24 pages, 11 figure
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