56,016 research outputs found

    Who Manages The Money? How Foundations Should Help Democratize Capital

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    For the past twenty-five years or more there has been a groundswell of activity among investment managers institutional investors, consultants and diversity advocates to democratize capital -- that is, to create more opportunities for diverse investment professionals and the firms they lead, to manage institutional capital This effort, grounded in both fiduciary and equity principles, has led to the growth of many diverse investment management firms like Progress Investment Management Company LLC ("Progress") and others. A range of stakeholders now recognizes that democratization of capital brings a range of positive benefits to our industry and society at larg

    Nanoscale Charge Balancing Mechanism in Alkali Substituted Calcium-Silicate-Hydrate Gels

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    Alkali-activated materials and related alternative cementitious systems are sustainable material technologies that have the potential to substantially lower CO2_2 emissions associated with the construction industry. However, the impact of augmenting the chemical composition of the material on the main binder phase, calcium-silicate-hydrate gel, is far from understood, particularly since this binder phase is disordered at the nanoscale. Here, we reveal the presence of a charge balancing mechanism at the molecular level, which leads to stable structures when alkalis (i.e., Na or K) are incorporated into a calcium-silicate-hydrate gel, as modeled using crystalline 14{\AA} tobermorite. These alkali containing charge balanced structures possess superior mechanical properties compared to their charge unbalanced counterparts. Our results, which are based on first-principles simulations using density functional theory, include the impact of charge balancing on the optimized geometries of the new model phases, formation energies, local bonding environments, bulk moduli and diffusion barriers of the alkali atoms within the crystals

    Towards a Molecular Inventory of Protostellar Discs

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    The chemical environment in circumstellar discs is a unique diagnostic of the thermal, physical and chemical environment. In this paper we examine the structure of star formation regions giving rise to low mass stars, and the chemical environment inside them, and the circumstellar discs around the developing stars.Comment: 9 page PDF, 550 kbyte

    Lagrangian Pairs and Lagrangian Orthogonal Matroids

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    Represented Coxeter matroids of types CnC_n and DnD_n, that is, symplectic and orthogonal matroids arising from totally isotropic subspaces of symplectic or (even-dimensional) orthogonal spaces, may also be represented in buildings of type CnC_n and DnD_n, respectively. Indeed, the particular buildings involved are those arising from the flags or oriflammes, respectively, of totally isotropic subspaces. There are also buildings of type BnB_n arising from flags of totally isotropic subspaces in odd-dimensional orthogonal space. Coxeter matroids of type BnB_n are the same as those of type CnC_n (since they depend only upon the reflection group, not the root system). However, buildings of type BnB_n are distinct from those of the other types. The matroids representable in odd dimensional orthogonal space (and therefore in the building of type BnB_n) turn out to be a special case of symplectic (flag) matroids, those whose top component, or Lagrangian matroid, is a union of two Lagrangian orthogonal matroids. These two matroids are called a Lagrangian pair, and they are the combinatorial manifestation of the ``fork'' at the top of an oriflamme (or of the fork at the end of the Coxeter diagram of DnD_n). Here we give a number of equivalent characterizations of Lagrangian pairs, and prove some rather strong properties of them.Comment: Requires amssymb.sty; 12 pages, 2 LaTeX figure

    A mathematical model for predicting cyclic voltammograms of electronically conductive polypyrrole

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    Polypyrrole is an attractive polymer for use as a high-energy-density secondary battery because of its potential as an inexpensive, lightweight, and noncorrosive electrode material. A mathematical model to simulate cyclic voltammograms for polypyrrole is presented. The model is for a conductive porous electrode film on a rotating disk electrode (RDE) and is used to predict the spatial and time dependence of concentration, overpotential, and stored charge profiles within a polypyrrole film. The model includes both faradic and capacitance charge components in the total current density expression
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