42,783 research outputs found

    From Structure to Function in Open Ionic Channels

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    We consider a simple working hypothesis that all permeation properties of open ionic channels can be predicted by understanding electrodiffusion in fixed structures, without invoking conformation changes, or changes in chemical bonds. We know, of course, that ions can bind to specific protein structures, and that this binding is not easily described by the traditional electrostatic equations of physics textbooks, that describe average electric fields, the so-called `mean field'. The question is which specific properties can be explained just by mean field electrostatics and which cannot. I believe the best way to uncover the specific chemical properties of channels is to invoke them as little as possible, seeking to explain with mean field electrostatics first. Then, when phenomena appear that cannot be described that way, by the mean field alone, we turn to chemically specific explanations, seeking the appropriate tools (of electrochemistry, Langevin, or molecular dynamics, for example) to understand them. In this spirit, we turn now to the structure of open ionic channels, apply the laws of electrodiffusion to them, and see how many of their properties we can predict just that way.Comment: Nearly final version of publicatio

    A palaeoecological approach to neotectonics : the geomorphic evolution of the Ntem River in and below its interior delta, SW Cameroon

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    The Late Tertiary to Quaternary evolution of the Ntem interior delta in SW Cameroon shall be modelled. A step fault was formed along neotectonically remobilized Precambrian structures. Uncalibrated 14C-datations in this ‘sediment trap’ show Pleistocene to Holocene ages. Both within and below the interior delta pebbles and clasts which are cemented in an iron and manganese matrix were found. These ‘fanglomerates’ are used to discuss different processes of the younger evolution also concerning climatic fluctuations in the study area

    Toward Ambidexterity

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    A poem

    Musical Property Rights Regimes in Tanzania and Kenya after TRIPS

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    Despite the passage of relatively uniform copyright legislation throughout East Africa and the formation of regional organizations meant to further standardize these laws, the protection of musical works in East African creative industries has varied significantly within and between Tanzania and Kenya. While enforcement remains weak throughout East Africa, each country has also taken a different path in the implementation of copyright policies meant to support musical property rights. These different trajectories can be explained, in large part, by the particular political, social and economic paths taken by East African countries toward the neoliberal present

    Space

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    Sound and space—however one defines these terms—are phenomenologically and ontologically intertwined
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