in the past, health planning in iran has been carried out in the context of short-range economic plans. although this mechanism has helped a great deal in the achievement of certain health plans however, the said scheme has been short in meeting the health objectives on a comprehensive basis. most often, the heath programs have lost their values to the priority and cost effectiveness of economi...

Amrican Association for the Advancemnt of Science Science serves its readers as a forum for the presentation and discussion of important issues related to the advancement of science, including the presentation of minority or conflicting points of view, rather than by publishing only material on which a consensus has been reached. Accordingly, all articles published in Science-including editoria...

Proteins are large and complex molecular machines. In order to perform their function, most of them need energy, e.g. either in the form of a photon, as in the case of the visual pigment rhodopsin, or through the breaking of a chemical bond, as in the presence of adenosine triphosphate (ATP). Such energy, in turn, has to be transmitted to specific locations, often several tens of A away from wh...