23,998 research outputs found

    Borderland Identity

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    Teen Sexuality and Pregnancy in Nevada

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    We begin this report by examining recent data regarding the national and Nevada specific trends in teen sexuality and pregnancy and discuss the socioeconomic determinants and disparities in teen pregnancy. Next, we focus on the national and local policies and programs designed to reduce teen pregnancy and to promote health equity among teenage youth. We conclude with a survey of programs that provide housing, case management, mental health services, life skills, career counseling and teen parenting education in Las Vegas and in Henderson, NV. Appendix provides information about local and national community resources that readers can use to further their understanding of the issues raised in this chapter and learn more about the best practices designed to prevent teen pregnancies

    Thin Sequences and Their Role in HpH^p Theory, Model Spaces, and Uniform Algebras

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    In this paper we revisit some facts about thin interpolating sequences in the unit disc from three perspectives: uniform algebras, model spaces, and HpH^p spaces. We extend the notion of asymptotic interpolation to HpH^p spaces, for 1≤p≤∞1 \leq p \leq \infty, providing several new ways to think about these sequences.Comment: v1: 21 pages; To appear in Rev. Mat. Iberoa

    Business forecasts 1978 : a year of moderate economic growth

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    An abstract for this article is not availableForecasting

    Assessing the Performance of the Diffusion Monte Carlo Method as Applied to the Water Monomer, Dimer, and Hexamer

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    The Diffusion Monte Carlo (DMC) method is applied to the water monomer, dimer, and hexamer, using q-TIP4P/F, one of the most simple, empirical water models with flexible monomers. The bias in the time step (Δτ\Delta\tau) and population size (NwN_w) is investigated. For the binding energies, the bias in Δτ\Delta\tau cancels nearly completely, while a noticeable bias in NwN_w still remains. However, for the isotope shift, (e.g, in the dimer binding energies between (H2_2O)2_2 and (D2_2O)2_2) the systematic errors in NwN_w do cancel. Consequently, very accurate results for the latter (within ∼0.01\sim 0.01 kcal/mol) are obtained with relatively moderate numerical effort (Nw∼103N_w\sim 10^3). For the water hexamer and its (D2_2O)6_6 isotopomer the DMC results as a function of NwN_w are examined for the cage and prism isomers. For a given isomer, the issue of the walker population leaking out of the corresponding basin of attraction is addressed by using appropriate geometric constraints. The population size bias for the hexamer is more severe, and in order to maintain accuracy similar to that of the dimer, the population size NwN_w must be increased by about two orders of magnitude. Fortunately, when the energy difference between cage and prism is taken, the biases cancel, thereby reducing the systematic errors to within ∼0.01\sim 0.01 kcal/mol when using a population of Nw=4.8×105N_w=4.8\times 10^5 walkers. Consequently, a very accurate result for the isotope shift is also obtained. Notably, both the quantum and the isotope effects for the prism-cage energy difference are small.Comment: 11 pages, 5 figures, 36 references. Submitted to the Journal of Physical Chemistr

    Fluorescence visualization of a convective instability which modulates the spreading of volatile surface films

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    The spontaneous spreading of a thin liquid film along the surface of a deep liquid layer of higher surface tension is a ubiquitous process which provides rapid and efficient surface transport of organic or biological material. For a source of constant concentration, the leading edge of a nonvolatile, immiscible film driven to spread by gradients in surface tension is known to advance as t^3/4 in time. Recent experiments using laser shadowgraphy to detect the advancing front of spreading films indicate, however, that immiscible but volatile sources of constant concentration spread with a reduced exponent according to t^1/2. Using a novel technique whereby fluorescent lines are inscribed in water, we have detected the evolution of a thermal instability beneath the leading edge of volatile films which strongly resembles a Rayleigh-Bénard roll. We propose that the increased dissipation from this rotational flow structure is likely responsible for the reduction in spreading exponent. This observation suggests a conceptual framework for coupling the effects of evaporation to the dynamics of spreading

    Spreading characteristics of an insoluble surfactant film on a thin liquid layer: comparison between theory and experiment

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    We describe measurements of the surface slope and reconstruction of the interface shape during the spreading of an oleic acid film on the surface of a thin aqueous glycerol mixture. This experimental system closely mimics the behaviour of an insoluble surfactant film driven to spread on a thin viscous layer under the action of a tangential (Marangoni) surface stress. Refracted image Moiré topography is used to monitor the evolution of the surface slope over macroscopic distances, from which the time variant interface shape and advancing speed of the surfactant film are inferred. The interfacial profile exhibits a strong surface depression ahead of the surfactant source capped by an elevated rim at the surfactant leading edge. The surface slope and shape as well as the propagation characteristics of the advancing rim can be compared directly with theoretical predictions. The agreement is quite strong when the model allows for a small level of pre-existing surface contamination of the initial liquid layer. Comparison between theoretical and experimental profiles reveals the importance of the initial shear stress in determining the evolution in the film thickness and surfactant distribution. This initial stress appears to thin the underlying liquid support so drastically that the surfactant droplet behaves as a finite and not an infinite source, even though there is always an excess of surfactant present at the origin
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