In spite of efforts to elucidate the structure and properties of the Mn center operating in the photo-synthetic apparatus of green plants and catalyzing the water oxidation reaction of eqn. (l), little is known about 2H,O- O2 t 4H+ t 4e- (1) the arrangement of the metal atoms, their ligation or their precise mode of action. A number of mech-anistic proposals have been presented e.g. [l-4], but none have been able to satisfactorily account for all the available EXAFS [5,6], EPR [7,8] and W-Vis data [9, lo]. Recent reviews of this area are available [ 11, 121. The photosynthetic Mn center is capable of cycling between five distinct oxidation levels,

prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at

a double integrator re-gardless of the magnitude of the input current. Ex-tensive experiments are then carried out in both time domain and frequency domain to show the effects of pivot nonlinearity and the effectiveness of the proposed compensator.

Abstract—This paper presents the design of a real pivot formed by a double-clamped beam for the rotational tuning structures in microelectromechanical systems (MEMS) tunable lasers. Micromechanical properties such as beam deformation, pivot position and pivot shift are investigated and compared

2 ATM-dependent cellular response to DNA double strand breaks plays a pivotal role in the maintenance of the integrity of the genome. Upon irradiation, Activated ATM proteins phosphorylate various downstream mediators and effectors, such as histone H2AX, MDC1, 53BP1 and NBS1. These proteins create

This is an open access article. Unrestricted non-commercial use is permitted provided the original work is properly cited. Open Access Full open access to this and thousands of other papers at

We extend recent work on flat plates undergoing imposed translation of their leading edge, hinged at the leading edge and free to pivot between 45 ° angle limiters, to several parameter studies. The first considers aspect ratio effects, with the finding that aspect ratio affects flowfield history

on these parameters. As a scaled sum of scores this pivot is convenient for bootstraps and double bootstraps, and leads to a meaningful concave consumption function. 1.

Abstract. The construction of a quantum groupoid out of a double groupoid satisfying a filling condition and a perturbation datum is given. Several important classes of examples of tensor categories are shown to fit into this construction. Certain invariants such as a pivotal grouplike element

and present a new polynomial time algorithm for reconstructing evolutionary trees called the Short Quartets Method which is consistent and which has greater statistical power than other polynomial time methods, such as Neighbor-Joining and the 3-approximation algorithm by Agarwala et al. (and the "Double