Dynamic characteristics of far-field radiation of current modulated phase-locked diode laser arrays

A versatile and powerful streak camera/frame grabber system for studying the evolution of the near and far field radiation patterns of diode lasers was assembled and tested. Software needed to analyze and display the data acquired with the steak camera/frame grabber system was written and the total package used to record and perform preliminary analyses on the behavior of two types of laser, a ten emitter gain guided array and a flared waveguide Y-coupled array. Examples of the information which can be gathered with this system are presented

Determination of stability constants using genetic algorithms

A genetic algorithm (GA)-simplex hybrid approach has been developed for the determination of stability constants using calorimetric and polarographic data obtained from literature sources. The GA determined both the most suitable equilibrium model for the systems studied and the values of the stability constants and the heats of formation for the calorimetric studies. As such, a variable length chromosome format was devised to represent the equilibrium models and stability constants (and heats of formation). The polarographic data were obtained from studies of cadmium chloride and lead with the crown ether dicyclohexyl-18-crown-6. The calorimetric data were obtained from a study of a two step addition reaction of Hg(CN)2 with thiourea. The stability constants obtained using the GA-simplex hybrid approach compare favourably with the values quoted in the literature

Regulation of pro-apoptotic phosphorylation of Kv2.1 K⁺ channels

Caspase activity during apoptosis is inhibited by physiological concentrations of intracellular K+. To enable apoptosis in injured cortical and hippocampal neurons, cellular loss of this cation is facilitated by the insertion of Kv2.1 K+ channels into the plasma membrane via a Zn2+ /CaMKII/SNARE-dependent process. Pro-apoptotic membrane insertion of Kv2.1 requires the dual phosphorylation of the channel by Src and p38 at cytoplasmic N- and C- terminal residues Y124 and S800, respectively. In this study, we investigate if these phosphorylation sites are mutually co-regulated, and whether putative N- and C-terminal interactions, possibly enabled by Kv2.1 intracellular cysteine residues C73 and C710, influence the phosphorylation process itself. Studies were performed with recombinant wild type and mutant Kv2.1 expressed in Chinese hamster ovary (CHO) cells. Using immunoprecipitated Kv2.1 protein and phospho-specific antibodies, we found that an intact Y124 is required for p38 phosphorylation of S800, and, importantly, that Src phosphorylation of Y124 facilitates the action of the p38 at the S800 residue. Moreover, the actions of Src on Kv2.1 are substantially decreased in the non-phosphorylatable S800A channel mutant. We also observed that mutations of either C73 or C710 residues decreased the p38 phosphorylation at S800 without influencing the actions of Src on tyrosine phosphorylation of Kv2.1. Surprisingly, however, apoptotic K+ currents were suppressed only in cells expressing the Kv2.1(C73A) mutant but not in those transfected with Kv2.1(C710A), suggesting a possible structural alteration in the C-terminal mutant that facilitates membrane insertion. These results show that intracellular N-terminal domains critically regulate phosphorylation of the C-terminal of Kv2.1, and vice versa, suggesting possible new avenues for modifying the apoptotic insertion of these channels during neurodegenerative processes

Spectral and picosecond temporal properties of flared guide Y‐coupled phase‐locked laser arrays

Spatio‐spectral and spatio‐temporal properties of flared waveguide ‘‘Y’’‐coupled laser arrays are investigated in both cw and pulsed operation. In each case, regular sustained self‐pulsations are exhibited. Destabilization of phase locking, caused by amplitude phase coupling, is thought to be the origin of the pulsations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70525/2/APPLAB-53-24-2380-1.pd

Spiral galaxy rotation curves determined from Carmelian general relativity

Equations of motion, in cylindrical co-ordinates, for the observed rotation of gases within the gravitational potential of spiral galaxies have been derived from Carmeli's Cosmological General Relativity theory. A Tully-Fisher type relation results and rotation curves are reproduced without the need for non-baryonic halo dark matter. Two acceleration regimes are discovered that are separated by a critical accleration $\approx 4.75 \times 10^{-10}$ $m.s^{-2}$. For accelerations larger than the critical value the Newtonian force law applies, but for accelerations less than the critical value the Carmelian regime applies. In the Newtonian regime the accelerations fall off as $r^{-2}$, but in the Carmelian regime the accelerations fall off as $r^{-1}$. This is new physics but is exactly what is suggested by Migrom's phenomenological MOND theory.Comment: 9 pages, 10 figures, Int. J. Theor. Phys, corrected typo