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

Conservation and human livelihoods at the crossroads : local needs and knowledge in the management of Arabuko Sokoke Forest

Arabuko Sokoke Forest is the largest remaining single block of indigenous dry coastal tropical forest in Eastern Africa. Households within a 5 km buffer zone depend heavily on the forest for their livelihood needs, and the pressure on forest resources is on the increase. In May 2015, 109 households were interviewed on resources they obtain from the forest, in terms of the self-reported level of monthly income. We found household income and farm size significantly positively correlated with benefits from the forest, highlighting the possible influence of household wealth in exploiting forest resources. A large proportion of households (32%) had limited knowledge of local birds, while human–bird conflict was reported by 44% of the households. While many households were keen to participate in conservation projects that maintain the forest, 44% had no knowledge of the forest management plan, and 60% of those interviewed had no idea of how forest zones were designated for particular activities. Drivers for local community participation in conservation projects appear to be sustainable income and fulfilment of basic household needs

A Novel Modulation and Demodulation Technique for the Downlink of Spread Spectrum

Abstract—In this letter, a novel method for modulation and demodulation of user information bit in spread spectrum code-division multiple-access (CDMA) systems is proposed. Synchronous CDMA poses intrinsic protection against co-channel interference due to orthogonal spreading codes used. However, in the presence of multipath, signals lose their orthogonality property, leading to an increased cross correlation. In this letter, we show that the performance of the system will be close to single user system if we assign two codes to each user and these two codes are used for modulation and demodulation. The well-known maximum length sequence codes are good candidates for the present modulation and demodulation technique. The limiting factor to the system capacity is the maximum number of codes and the capacity is half of that number. Index Terms—Code-division multiple access (CDMA), demodulation, modulation, spread spectrum. I

The Dead Walk

The Zombie Walk in Brisbane is a chance for people who love scaring onlookers to dress up like the "dead who walk"