655 research outputs found

    Homeowners’ Willingness to Adopt Environmentally Beneficial Landscape Practices in an Urbanizing Watershed

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    Streams in urbanizing watersheds often experience low flows in summer due to increased water use for residential landscaping and decreased base flow as impervious land cover limits aquifer recharge. Environmentally beneficial landscape practices that save water and infiltrate runoff have the potential to provide multiple ecological benefits including reducing stress on urban streams, but can face opposition by local homeowners. Thus, this study explored attitudes toward landscape water conservation including the barriers and motivations that exist to adoption of water conserving landscape practices by residents in the Ipswich River watershed north of Boston, Massachusetts (USA) that experiences seasonal water shortages. The study used a mail-out and on-line survey with images of different water conserving landscape practices (including rain gardens and native plantings) and questions about homeowners’ watering practices, likelihood of adopting these landscape practices, and attitudes towards environmental issues in the region, including existing water policies to restrict use. The results showed that residents (n=265) were aware of existing water shortages and supportive of water conservation policies. Their willingness to adopt water conserving landscape practices was influenced by aesthetic preference with more support for practices that appeared neat rather than those that appeared unkempt. Barriers to residential adoption of these landscape practices included concern about disease-carrying pests and the perceived cost of landscape change. Knowledge about the environment, as operationalized by membership in a local watershed association, as well as educational attainment and income were statistically significant variables in predicting aesthetic preferences and willingness to adopt landscape practices. Promoting widespread adoption of water conserving landscape practices could benefit from local community support and educational initiatives about the multiple-benefits of these practices, including potential long-term cost savings for homeowners. Residential landscape design and management, however, are only part of overarching policy changes that could address water conservation in urbanizing watersheds

    Towards a unified theory of Sobolev inequalities

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    We discuss our work on pointwise inequalities for the gradient which are connected with the isoperimetric profile associated to a given geometry. We show how they can be used to unify certain aspects of the theory of Sobolev inequalities. In particular, we discuss our recent papers on fractional order inequalities, Coulhon type inequalities, transference and dimensionless inequalities and our forthcoming work on sharp higher order Sobolev inequalities that can be obtained by iteration.Comment: 39 pages, made some changes to section 1

    Microwave radiometric observations near 19.35, 92 and 183 GHz of precipitation in tropical storm Cora

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    Observations of rain cells in the remains of a decaying tropical storm were made by Airborne Microwave Radiometers at 19.35,92 and three frequencies near 183 GHz. Extremely low brightness temperatures, as low as 140 K were noted in the 92 and 183 GHz observations. These can be accounted for by the ice often associated with raindrop formation. Further, 183 GHz observations can be interpreted in terms of the height of the ice. The brightness temperatures observed suggest the presence of precipitation sized ice as high as 9 km or more

    Bogoliubov Excitations of Disordered Bose-Einstein Condensates

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    We describe repulsively interacting Bose-Einstein condensates in spatially correlated disorder potentials of arbitrary dimension. The first effect of disorder is to deform the mean-field condensate. Secondly, the quantum excitation spectrum and condensate population are affected. By a saddle-point expansion of the many-body Hamiltonian around the deformed mean-field ground state, we derive the fundamental quadratic Hamiltonian of quantum fluctuations. Importantly, a basis is used such that excitations are orthogonal to the deformed condensate. Via Bogoliubov-Nambu perturbation theory, we compute the effective excitation dispersion, including mean free paths and localization lengths. Corrections to the speed of sound and average density of states are calculated, due to correlated disorder in arbitrary dimensions, extending to the case of weak lattice potentials.Comment: 23 pages, 11 figure

    Notes about the Caratheodory number

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    In this paper we give sufficient conditions for a compactum in Rn\mathbb R^n to have Carath\'{e}odory number less than n+1n+1, generalizing an old result of Fenchel. Then we prove the corresponding versions of the colorful Carath\'{e}odory theorem and give a Tverberg type theorem for families of convex compacta

    Evidence for Narrow N*(1685) Resonance in Quasifree Compton Scattering on the Neutron

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    The first study of quasi-free Compton scattering on the neutron in the energy range of Eγ=0.751.5E_{\gamma}=0.75 - 1.5 GeV is presented. The data reveals a narrow peak at W1.685W\sim 1.685 GeV. This result, being considered in conjunction with the recent evidence for a narrow structure at W1.68W\sim 1.68GeV in the η\eta photoproduction on the neutron, suggests the existence of a new nucleon resonance with unusual properties: the mass M1.685M\sim 1.685GeV, the narrow width Γ30\Gamma \leq 30MeV, and the much stronger photoexcitation on the neutron than on the proton.Comment: Replaced with the version published in Phys. Rev.

    A Multiscale Approach to Determination of Thermal Properties and Changes in Free Energy: Application to Reconstruction of Dislocations in Silicon

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    We introduce an approach to exploit the existence of multiple levels of description of a physical system to radically accelerate the determination of thermodynamic quantities. We first give a proof of principle of the method using two empirical interatomic potential functions. We then apply the technique to feed information from an interatomic potential into otherwise inaccessible quantum mechanical tight-binding calculations of the reconstruction of partial dislocations in silicon at finite temperature. With this approach, comprehensive ab initio studies at finite temperature will now be possible.Comment: 5 pages, 3 figure

    Effects of pressure on diffusion and vacancy formation in MgO from non-empirical free-energy integrations

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    The free energies of vacancy pair formation and migration in MgO were computed via molecular dynamics using free-energy integrations and a non-empirical ionic model with no adjustable parameters. The intrinsic diffusion constant for MgO was obtained at pressures from 0 to 140 GPa and temperatures from 1000 to 5000 K. Excellent agreement was found with the zero pressure diffusion data within experimental error. The homologous temperature model which relates diffusion to the melting curve describes well our high pressure results within our theoretical framework.Comment: 4 pages, latex, 1 figure, revtex, submitted to PR

    The multiplicative property characterizes p\ell_p and LpL_p norms

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    We show that p\ell_p norms are characterized as the unique norms which are both invariant under coordinate permutation and multiplicative with respect to tensor products. Similarly, the LpL_p norms are the unique rearrangement-invariant norms on a probability space such that XY=XY\|X Y\|=\|X\|\cdot\|Y\| for every pair X,YX,Y of independent random variables. Our proof relies on Cram\'er's large deviation theorem.Comment: 8 pages, 1 figur
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