7,730 research outputs found

    A Method to Calculate Fission-Fragment Yields Y(Z,N)Y(Z,N) versus Proton and Neutron Number in the Brownian Shape-Motion Model. Application to calculations of U and Pu charge yields

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    We propose a method to calculate the two-dimensional (2D) fission-fragment yield Y(Z,N)Y(Z,N) versus both proton and neutron number, with inclusion of odd-even staggering effects in both variables. The approach is to use Brownian shape-motion on a macroscopic-microscopic potential-energy surface which, for a particular compound system is calculated versus four shape variables: elongation (quadrupole moment Q2Q_2), neck dd, left nascent fragment spheroidal deformation ϵf1\epsilon_{\rm f1}, right nascent fragment deformation ϵf2\epsilon_{\rm f2} and two asymmetry variables, namely proton and neutron numbers in each of the two fragments. The extension of previous models 1) introduces a method to calculate this generalized potential-energy function and 2) allows the correlated transfer of nucleon pairs in one step, in addition to sequential transfer. In the previous version the potential energy was calculated as a function of ZZ and NN of the compound system and its shape, including the asymmetry of the shape. We outline here how to generalize the model from the "compound-system" model to a model where the emerging fragment proton and neutron numbers also enter, over and above the compound system composition

    South Africa’s new democrats : a 2002 profile of democracy in the making

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    [From the introduction]: South Africa’s dramatic conversion to democracy has been heralded as a modern-day miracle. In former Nobel peace prize winner Archbishop Tutu’s words, it was ‘touch and go’ whether all conflicting parties would participate in the first non-racial elections in April 1994. The ‘rainbow nation’, as the new South Africa liked to call itself in the first years of democracy, was heralded as a beacon of hope and enlightenment for Africa and the world. Since 1994, South Africa has successfully conducted two further national elections that have been declared essentially free and fair. The country has emerged as a leading representative of the economic and political interests of developing countries and the South in the international arena. The question is whether living under democracy has influenced the manner in which South Africans see themselves, their country and the world around them. This report seeks to document how South Africans think and feel some eight years into democracy about issues that are important in their own lives and have significance for the future of their society. The study covers personal experiences, attitudes and beliefs, and the aspirations and fears of ordinary people. It seeks to identify the sentiments and collective experiences that may contribute to or hinder the consolidation of democracy in years to come. The report is based on an inquiry conducted in March 2002 among over two thousand South African adults over 16 years of age in a nationally representative MarkData survey that included all regions of the country.Lettres de Byblos / Letters from Byblos. A series of occasional papers published by UNESCO Centre International des Sciences de l’Homme International Centre for Human Science

    No problem! Avoidance of cultural diversity in teacher training

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    Research all over the world indicates that initial teacher training, as far as multicultural education is concerned, is grossly inadequate or, in many instances, non-existent. In many cases it is still regarded as a luxury which cannot be afforded in a time of scarcity of resources, or as a contentious politically sensitive area best avoided. Avoidance or so-called ";no problem!"; strategies are often the outcome of teacher training that fails or falls short of addressing issues of diversity in schools. There is much talk worldwide of permeating a multicultural perspective in teacher training programmes. Most educational stakeholders agree on the feasibility of training prospective teachers to teach in a multicultural society. In practice, however, very little, if anything (in some cases), is being done to impregnate existing initial teacher training courses with a pluralistic vision or perspective. Teachers cannot be expected to be effective in teaching multicultural content and working effectively with ethnically diverse student groups without being professionally prepared for this task. (South African Journal of Education: 2003 22(3): 184-187

    The Multiphase Intracluster Medium in Galaxy Groups Probed by the Lyman Alpha Forest

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    The case is made that the intracluster medium (ICM) in spiral-rich galaxy groups today probably has undergone much slower evolution than that in elliptical-rich groups and clusters. The environments of proto-clusters and proto-groups at z > 2 are likely similar to spiral-rich group environments at lower redshift. Therefore, like the ICM in spiral-rich groups today, the ICM in proto-groups and proto-clusters at z > 2 is predicted to be significantly multiphased. The QSO Lyman alpha forest in the vicinity of galaxies is an effective probe of the ICM at a wide range of redshift. Two recent observations of Lyman alpha absorption around galaxies by Adelberger et al. and by Pascarelle et al are reconciled, and it is shown that observations support the multiphase ICM scenario. Galaxy redshifts must be very accurate for such studies to succeed. This scenario can also explain the lower metallicity and lower hot gas fraction in groups.Comment: 4 pages, 1 figure, replaced with the version after proo

    The Properties of Field Elliptical Galaxies at Intermediate Redshift. I: Empirical Scaling Laws

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    We present measurements of the Fundamental Plane (FP) parameters (the effective radius, the mean effective surface brightness, and the central velocity dispersion) of six field elliptical galaxies at intermediate redshift. The imaging is taken from the Medium Deep Survey of the Hubble Space Telescope, while the kinematical data are obtained from long-slit spectroscopy using the 3.6-m ESO telescope. The Fundamental Plane appears well defined in the field even at redshift \approx 0.3. The data show a shift in the FP zero point with respect to the local relation, possibly indicating modest evolution, consistent with the result found for intermediate redshift cluster samples. The FP slopes derived for our field data, plus other cluster ellipticals at intermediate redshift taken from the literature, differ from the local ones, but are still consistent with the interpretation of the FP as a result of homology, of the virial theorem and of the existence of a relation between luminosity and mass, LMηL \propto M^{\eta}. We also derive the surface brightness vs. effective radius relation for nine galaxies with redshift up to z0.6z \approx0.6, and data from the literature; the evolution that can be inferred is consistent with what is found using the FP.Comment: 17 pages, including 9 figures, MNRAS, accepte

    DGNB building certification companion: Sustainability Tool for Assessment, Planning, Learning, and Engaging (STAPLE)

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    In the construction industry, the popularity of sustainability and its benefits have been on the rise in recent years. Alas, with various building sustainability assessment schemes on the market, there is still no single general method for a comprehensive and inclusive design and building process for sustainable buildings. The literature describes several barriers of entry preventing actors in the industry from seeking sustainability certifications and prioritizing design methods, supporting sustainability in greater numbers. In the newly developed tool, “DGNB building certification companion: Sustainable Tool for Assessment, Planning, Learning, and Engaging (STAPLE)”, a new Excel-based, interactive, and iterative education focused platform is introduced, intended to engage dialog among stakeholders, building owners, and decision makers, and the assigned group team leaders, based on the five DGNB topics. In order to establish common levels of knowledge, terminology, and understanding for proper interdisciplinary discussions, which would result in suitable and timely decisions, personal and professional development is enabled by imbedded educational documents in multiple formats throughout the tool as plain-language, easily digestible summaries of various topics regarding sustainability and the DGNB certification scheme. The identified barriers are described in the tool followed by a solution to overcome them. The tool, tested at multiple stages of development and moulded by many individuals both within and outside of the sustainable building industry, has shown to achieve the primary goals of assessment of individual’s current knowledge, educating through multiple stages and formats, and the inspiring of conversation among team members through a graphical display of opinions. Based on user feedback, the conclusion was that this is a desired product on the market. This new approach is expected to dramatically reduce misunderstandings, conflicts, and mistakes during a sustainable design process, helping the design team plan a project to possibly obtain the highest DGNB score if desired and properly documented
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