3D mesh refinement procedure using the bisection and rivara algorithms with mesh quality assessment

Mesh refinement procedures for the solution of three dimensional problems are described. The computational\ud domain is represented by an assembly of tetrahedral elements and the mesh refinement is acheived by the bisection\ud and Rivara methods using an explicit mesh density function coupled with an automatic 3D mesh generator.\ud A couple of benchmark examples is used to compare the performance of both refinement methods in terms of mesh\ud and size qualities, number of generated elements and CPU time consume

Case of Thomas P. Boden, the Consumptive Irish Immigrant.: Its Medical, Sociological, International and Humanitarian Aspect.

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Alfred A. Knopf to Mr. Silver, 16 May 1956

Personal correspondenc

Alfred A Knopf to Mr. Silver, undated

Professional correspondenc

Alfred A. Knopf to Mr. Silver, 25 November 1960

Professional correspondenc

Empowering Latino parents to transform the education of their children

This article emphasizes the role of parental involvement in the college preparation of Latino elementary and secondary school students. Although literature shows that education is highly valued in Latino families, actual college enrollment rates for Latino youth are below average. This has been attributed to barriers including lack of financial resources, problems in communication with schools, and low familiarity with the college planning process. The American Dream Academy is a university outreach program that is designed to help Latino families overcome these barriers. We conducted a qualitative analysis of speeches that were prepared and delivered by parents at graduation ceremonies of the program from 2007 to 2009. Our analysis revealed six themes: facing challenges, envisioning success, understanding the school system, taking ownership, community raising a child, and creating a supportive home environment. The findings enrich existing literature and help understand the complex systems that are at play with parental involvement in Latino families

Ice nucleation from aqueous NaCl droplets with and without marine diatoms

Ice formation in the atmosphere by homogeneous and heterogeneous nucleation is one of the least understood processes in cloud microphysics and climate. Here we describe our investigation of the marine environment as a potential source of atmospheric IN by experimentally observing homogeneous ice nucleation from aqueous NaCl droplets and comparing against heterogeneous ice nucleation from aqueous NaCl droplets containing intact and fragmented diatoms. Homogeneous and heterogeneous ice nucleation are studied as a function of temperature and water activity, <i>a</i><sub>w</sub>. Additional analyses are presented on the dependence of diatom surface area and aqueous volume on heterogeneous freezing temperatures, ice nucleation rates, ω<sub>het</sub>, ice nucleation rate coefficients, <i>J</i><sub>het</sub>, and differential and cumulative ice nuclei spectra, <i>k(T)</i> and <i>K(T)</i>, respectively. Homogeneous freezing temperatures and corresponding nucleation rate coefficients are in agreement with the water activity based homogeneous ice nucleation theory within experimental and predictive uncertainties. Our results confirm, as predicted by classical nucleation theory, that a stochastic interpretation can be used to describe the homogeneous ice nucleation process. Heterogeneous ice nucleation initiated by intact and fragmented diatoms can be adequately represented by a modified water activity based ice nucleation theory. A horizontal shift in water activity, Δ<i>a</i><sub>w, het</sub> = 0.2303, of the ice melting curve can describe median heterogeneous freezing temperatures. Individual freezing temperatures showed no dependence on available diatom surface area and aqueous volume. Determined at median diatom freezing temperatures for <i>a</i><sub>w</sub> from 0.8 to 0.99, ω<sub>het</sub><u>~</u>0.11<sup>+0.06</sup><sub>−0.05</sub> s<sup>−1</sup>, <i>J</i><sub>het</sub><u>~</u>1.0<sup>+1.16</sup><sub>−0.61</sub>×10<sup>4</sup> cm<sup>−2</sup> s<sup>−1</sup>, and <i>K</i><u>~</u>6.2<sup>+3.5</sup><sub>−4.1</sub> ×10<sup>4</sup> cm<sup>−2</sup>. The experimentally derived ice nucleation rates and nuclei spectra allow us to estimate ice particle production which we subsequently use for a comparison with observed ice crystal concentrations typically found in cirrus and polar marine mixed-phase clouds. Differences in application of time-dependent and time-independent analyses to predict ice particle production are discussed

New Dimensions for Wound Strings: The Modular Transformation of Geometry to Topology

We show, using a theorem of Milnor and Margulis, that string theory on compact negatively curved spaces grows new effective dimensions as the space shrinks, generalizing and contextualizing the results in hep-th/0510044. Milnor's theorem relates negative sectional curvature on a compact Riemannian manifold to exponential growth of its fundamental group, which translates in string theory to a higher effective central charge arising from winding strings. This exponential density of winding modes is related by modular invariance to the infrared small perturbation spectrum. Using self-consistent approximations valid at large radius, we analyze this correspondence explicitly in a broad set of time-dependent solutions, finding precise agreement between the effective central charge and the corresponding infrared small perturbation spectrum. This indicates a basic relation between geometry, topology, and dimensionality in string theory.Comment: 28 pages, harvmac big. v2: references and KITP preprint number added, minor change