5,079 research outputs found

    Implementing the Simple Biosphere Model (SiB) in a general circulation model: Methodologies and results

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    The Simple Biosphere MOdel (SiB) of Sellers et al., (1986) was designed to simulate the interactions between the Earth's land surface and the atmosphere by treating the vegetation explicitly and relistically, thereby incorporating biophysical controls on the exchanges of radiation, momentum, sensible and latent heat between the two systems. The steps taken to implement SiB in a modified version of the National Meteorological Center's spectral GCM are described. The coupled model (SiB-GCM) was used with a conventional hydrological model (Ctl-GCM) to produce summer and winter simulations. The same GCM was used with a conventional hydrological model (Ctl-GCM) to produce comparable 'control' summer and winter variations. It was found that SiB-GCM produced a more realistic partitioning of energy at the land surface than Ctl-GCM. Generally, SiB-GCM produced more sensible heat flux and less latent heat flux over vegetated land than did Ctl-GCM and this resulted in the development of a much deeper daytime planetary boundary and reduced precipitation rates over the continents in SiB-GCM. In the summer simulation, the 200 mb jet stream and the wind speed at 850 mb were slightly weakened in the SiB-GCM relative to the Ctl-GCM results and equivalent analyses from observations

    Bistable molecular conductors with a field-switchable dipole group

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    A class of bistable "stator-rotor" molecules is proposed, where a stationary bridge (stator) connects the two electrodes and facilitates electron transport between them. The rotor part, which has a large dipole moment, is attached to an atom of the stator via a single sigma bond. Hydrogen bonds formed between the rotor and stator make the symmetric orientation of the dipole unstable. The rotor has two potential minima with equal energy for rotation about the sigma bond. The dipole orientation, which determines the conduction state of the molecule, can be switched by an external electric field that changes the relative energy of the two potential minima. Both orientation of the rotor correspond to asymmetric current-voltage characteristics that are the reverse of each other, so they are distinguishable electrically. Such bistable stator-rotor molecules could potentially be used as parts of molecular electronic devices.Comment: 8 pages, 7 figure

    Spectrum of Sizes for Perfect Deletion-Correcting Codes

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    One peculiarity with deletion-correcting codes is that perfect tt-deletion-correcting codes of the same length over the same alphabet can have different numbers of codewords, because the balls of radius tt with respect to the Levenshte\u{\i}n distance may be of different sizes. There is interest, therefore, in determining all possible sizes of a perfect tt-deletion-correcting code, given the length nn and the alphabet size~qq. In this paper, we determine completely the spectrum of possible sizes for perfect qq-ary 1-deletion-correcting codes of length three for all qq, and perfect qq-ary 2-deletion-correcting codes of length four for almost all qq, leaving only a small finite number of cases in doubt.Comment: 23 page

    Implications of translational research for the field of residential child care

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    This article will address a brief history of the nature and definition of translational research and introduce several relevant debates within the field of translational research, specifically the relationship between practice-based knowledge and research in therapeutic residential child care. We offer a model of translational research developed by Hamilton (2014), particularly for work related to youth development that has the potential to bring the child care practitioner to the centre of the process to improve the outcomes of high-needs children. Finally, we provide some lessons learned from the implementation and evaluation of two major programmes designed to improve the quality of therapeutic residential care
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