Symmetry Decomposition of Chaotic Dynamics

Discrete symmetries of dynamical flows give rise to relations between periodic orbits, reduce the dynamics to a fundamental domain, and lead to factorizations of zeta functions. These factorizations in turn reduce the labor and improve the convergence of cycle expansions for classical and quantum spectra associated with the flow. In this paper the general formalism is developed, with the $N$-disk pinball model used as a concrete example and a series of physically interesting cases worked out in detail.Comment: CYCLER Paper 93mar01

Abyssal hydrothermal springs-Cryptic incubators for brooding octopus

Does warmth from hydrothermal springs play a vital role in the biology and ecology of abyssal animals? Deep off central California, thousands of octopus (Muusoctopus robustus) migrate through cold dark waters to hydrothermal springs near an extinct volcano to mate, nest, and die, forming the largest known aggregation of octopus on Earth. Warmth from the springs plays a key role by raising metabolic rates, speeding embryonic development, and presumably increasing reproductive success; we show that brood times for females are ∼1.8 years, far faster than expected for abyssal octopods. Using a high-resolution subsea mapping system, we created landscapescale maps and image mosaics that reveal 6000 octopus in a 2.5-ha area. Because octopuses die after reproducing, hydrothermal springs indirectly provide a food supplement to the local energy budget. Although localized deep-sea heat sources may be essential to octopuses and otherwarm-tolerant species, most of these unique and often cryptic habitats remain undiscovered and unexplored

Five million years of compositionally diverse, episodic volcanism : construction of Davidson Seamount atop an abandoned spreading center

Davidson Seamount, a volcano located about 80 km off the central California coast, has a volume of ~320 km³ and consists of a series of parallel ridges serrated with steep cones. Davidson was sampled and its morphology observed during 27 ROV Tiburon dives. During those dives, 286 samples of lava, volcaniclastite, and erratics from the continental margin were collected, with additional samples from one ROV-collected push core and four gravity cores. We report glass compositions for 99 samples and ⁴⁰Ar-³⁹Ar incremental heating age data for 20 of the samples. The glass analyses are of hawaiite (62%), mugearite (13%), alkalic basalt (9%), and tephrite (8%), with minor transitional basalt (2%), benmoreite (2%), and trachyandesite (2%). The lithologies are irregularly distributed in space and time. The volcano erupted onto crust inferred to be 20 Ma from seafloor magnetic anomalies. Ages of the lavas range from 9.8 to 14.8 Ma. The oldest rocks are from the central ridge, and the youngest are from the flanks and southern end of the edifice. The compositions of the 18 reliably dated volcanic cones vary with age such that the oldest lavas are the most fractionated. The melts lost 65% to nearly 95% of their initial S because of bubble loss during vesiculation, and the shallowest samples have S contents similar to lava erupted subaerially in Hawaii. Despite this similarity in S contents, there is scant other evidence to suggest that Davidson was ever an island. The numerous small cones of disparate chemistry and the long eruptive period suggest episodic growth of the volcano over at least 5 Myr and perhaps as long as 10 Myr if it began to grow when the spreading ridge was abandoned

Regulation of inositol 1,4,5-trisphosphate-induced Ca2+ release by reversible phosphorylation and dephosphorylation

AbstractThe inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) is a universal intracellular Ca2+-release channel. It is activated after cell stimulation and plays a crucial role in the initiation and propagation of the complex spatio-temporal Ca2+ signals that control cellular processes as different as fertilization, cell division, cell migration, differentiation, metabolism, muscle contraction, secretion, neuronal processing, and ultimately cell death. To achieve these various functions, often in a single cell, exquisite control of the Ca2+ release is needed. This review aims to highlight how protein kinases and protein phosphatases can interact with the IP3R or with associated proteins and so provide a large potential for fine tuning the Ca2+-release activity and for creating efficient Ca2+ signals in subcellular microdomains

Role of IP3 Receptors during Early Zebrafish Development.

Fluctuations in cytosolic Ca2+ are crucial for a variety of cellular processes including many aspects of development. Mobilization of intracellular Ca2+ stores via the production of inositol trisphosphate (IP3) and the consequent activation of IP3-sensitive Ca2+ channels is a ubiquitous means by which diverse stimuli mediate their cellular effects. Although IP3 receptors have been well studied at fertilization, information regarding their possible involvement during subsequent development is scant. In the present study we examined the role of IP3 receptors in early development of the zebrafish. We report the first molecular analysis of zebrafish IP3 receptors which indicates that, like mammals, the zebrafish genome contains three distinct IP3 receptor genes. mRNA for all isoforms was detectable at differing levels by the 64 cell stage, and IP3-induced Ca2+ transients could be readily generated (by flash photolysis) in a controlled fashion throughout the cleavage period in vivo. Furthermore, we show that early blastula formation was disrupted by pharmacological blockade of IP3 receptors or phospholipase C, by molecular inhibition of the former by injection of IRBIT (IP3 receptor-binding protein released with IP3) and by depletion of thapsigargin-sensitive Ca2+ stores after completion of the second cell cycle. Inhibition of Ca2+ entry or ryanodine receptors, however, had little effect. Our work defines the importance of IP3 receptors during early development of a genetically and optically tractable model vertebrate organism