43,152 research outputs found
From Structure to Function in Open Ionic Channels
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
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
Bankruptcy in the Administrative State
A national interacting metasystem of national education and fostering developed in the Finnish speaking region Tornedalen in northern Sweden from the late 19th century to the 1950s. It was not formally agreed as a deliberate education system, but was more of a tacit understanding of a common nationalistic goal within different educational institutions such as primary schools, the residential industrial schools [arbetsstugor], the folk high-schools and the different forms of explicit military education. The aim was to help the poor region economically, to spread the Swedish language and culture in the area, to break the isolation of the region through education and to integrate this geopolitically sensitive border region into the nation. The integrative phase of Swedish nationalism was a common denominator. Leading persons in the educational and fostering activities were many times the same persons. There was a consensus over party lines about the need of acculturation and assimilation of the Tornedalians. The school, the nation and the family was regarded as central concepts in the fostering of the minority into Swedish citizens. By regarding the educations in Tornealen as a metasystem of ideological influences you get an imagination of the ideological power single educations gets when interconnected as a system
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