Ultimate ocean depth packaging for a digital ring laser gyroscope

A Honeywell GG 1320AN Digital Ring Laser Gyroscope (RLG), typically an aviation sensor, has been adapted for use as part of a navigation package rated to ocean depths of 6,000 meters. Researchers and engineers at the Deep Submergence Laboratory (DSL) of the Woods Hole Oceanographic Institution (WHOI) designed a high-density instrument package around the basic RLG. The integrated instrument is modular and field serviceable. It includes a chassis, housing, a Crossbow 6-axis dynamic measurement unit (DMU), battery backup, power regulation, support circuitry and robust interfaces. A pressure-proof titanium case and non-corroding accessories ensure that the RLG will remain unaffected by prolonged immersion in seawater. Associated mounting bracketry allow the housing to be axially registered alongside the navigation suites of various deep diving WHOI assets, or with any host platform capable of caring a 25 pound payload. Primary RLG platforms will be the manned deep submergence vehicle ALVIN, the unmanned remotely operated vehicle JASON, and the unmanned autonomous vehicle ABE. As an extremely accurate yaw rate measuring device, the RLG will provide navigation data far more reliable and precise that has been available to scientists in the past. The WHOI RLG has been used successfully on one JASON cruise.Funding was provided by the National Science Foundation under Grant No. OCE-9710512

A passive capture latch for ODYSSEY-class AUVs

Under subcontract to the Massachusetts Institute of Techology's (MIT) Sea Grant Autonomous Ocean Sampling Network (AOSN) program, the Woods Hole Oceanographic Institution's Deep Submergence Laboratory (WHOI-DSL) produced a passive capture latch for ODYSSEY -class autonomous underwater vehicles (AUVs). The latch is an all-titanium, split tine device, shock-mounted to the bow of the AUV. When the AUV concludes a survey mission and returns to a moored, midwater docking station, the latch leads the AUV's approach and is the first device to collide with the station's vertical docking pole. Latching to the pole is an entirely passive event requiring only forward motion of the AUV. A positive capture indication generated by proximity switches mounted on the device initiates AUV power and data transfer servicing by the station. Unlatching action requires one revolution of a latch motor cam and a brief backing command to the AUV thruster. The possibility of system malfunction was considered in latch design. If for any reason the latched vehicle canot perform normal unlatching behavior, or the station fails, the latch defaults by securing the AUV to the moored station indefinitely. Two WHOI AUV latches have been used successfully on three offshore engineering test cruises.Funding was provided by the Offce of Naval Research under Grant No. NOOO-14-95-1-1316

The Quantum Measurement Spintronic Engine: Using Entanglement to Harvest Vacuum Fluctuations

Several experimental reports have described electrical power output by electronic devices that channel spin-polarized currents across paramagnetic centers. Phononic radiation have been proposed as the source of the engine's energy, though other hypotheses, such as quantum vacuum fluctuations, should also be examined. This paper is the first of a series which will address these hypotheses. Herein, we investigate the more basic hypothesis that quantum vacuum fluctuations power a quantum engine that converts entanglement energy into useful electrical work. The system under review is composed of two atom-level quantum dots that are tunnel-coupled and exhibit a magnetic exchange interaction. This working substance is connected in series with two ferromagnetic electrodes. The engine cycle comprises two strokes. The thermalizing stroke puts the system into equilibrium with the electrode baths, leading to a release of electrical energy into the leads and to an increase in the system entropy due to entanglement. Then the measurement stroke breaks the entanglement between the two quantum dots, thereby reducing its entropy while energizing it on average. Using a perturbative master equation approach, we analytically demonstrate the efficiency of the engine, and we study the cycle numerically to gain insight into the relevant parameters to maximize power. Although the possibility of harvesting energy from the quantum vacuum fluctuations and the interactions with the baths is proven on paper and confirmed by numerical experiments, the efficiency remains low and is unstable. Our results indicate that quantum vacuum fluctuations alone are unlikely to be the energy source in the the quantum spintronic engine experiments that have been reported thus far

Extraordinarily high leaf selenium to sulfur ratios define ‘se-accumulator’ plants

Background and Aims: Selenium (Se) and sulfur (S) exhibit similar chemical properties. In flowering plants (angiosperms) selenate and sulfate are acquired and assimilated by common transport and metabolic pathways. It is hypothesized that most angiosperm species show little or no discrimination in the accumulation of Se and S in leaves when their roots are supplied a mixture of selenate and sulfate, but some, termed Se-accumulator plants, selectively accumulate Se in preference to S under these conditions. Methods: This paper surveys Se and S accumulation in leaves of 39 angiosperm species, chosen to represent the range of plant Se accumulation phenotypes, grown hydroponically under identical conditions. Results: The data show that, when supplied a mixture of selenate and sulfate: (1) plant species differ in both their leaf Se ([Se]leaf) and leaf S ([S]leaf) concentrations; (2) most angiosperms show little discrimination for the accumulation of Se and S in their leaves and, in non-accumulator plants, [Se]leaf and [S]leaf are highly correlated; (3) [Se]leaf in Se-accumulator plants is significantly greater than in other angiosperms, but [S]leaf, although high, is within the range expected for angiosperms in general; and (4) the Se/S quotient in leaves of Se-accumulator plants is significantly higher than in leaves of other angiosperms. Conclusion: The traits of extraordinarily high [Se]leaf and leaf Se/S quotients define the distinct elemental composition of Se-accumulator plants

Integrating Mine Development Planning with Resource Management Strategy

2010 S.C. Water Resources Conference - Science and Policy Challenges for a Sustainable Futur

A deep sea docking station for ODYSSEY class autonomous underwater vehicles

Under subcontract to the Massachusetts Institute of Technology's (MIT) Sea Grant Autonomous Ocean Sampling Network (AOSN) program, engineers and researchers at the Woods Hole Oceanographic Institution (WHOI) designed, fabricated and operated a deep sea Docking Station for ODYSSEY-class autonomous underwater vehicles (AUVs). The docking station provides shelter as well as power transfer and data exchange services for an AUV that is between autonomous midwater missions. The Station is integrated into the main tension member of a deep sea mooring system. A large subsea flotation sphere supports the mass of the Station above the seafoor. A surface expression connected by an umbilcal to the Station was capable of bi-directional satellite or radio frequency communications. Primary subsystems of the Docking Station described in this report include a dock controller with multi-sensor support, long-duration battery packs, a docking pole with a moving carage, an inductive link for power and data transfer, and information about how the Station was deployed, operated and recovered.Funding was provided by the Offce of Naval Research under Grant No. NOOO-14-95-1-1316

The MgII Cross-section of Luminous Red Galaxies

We describe a search for MgII(2796,2803) absorption lines in Sloan Digital Sky Survey (SDSS) spectra of QSOs whose lines of sight pass within impact parameters of 200 kpc of galaxies with photometric redshifts of z=0.46-0.6 and redshift errors Delta z~0.05. The galaxies selected have the same colors and luminosities as the Luminous Red Galaxy (LRG) population previously selected from the SDSS. A search for Mg II lines within a redshift interval of +/-0.1 of a galaxy's photometric redshift shows that absorption by these galaxies is rare: the covering fraction is ~ 10-15% between 20 and 100 kpc, for Mg II lines with rest equivalent widths of Wr >= 0.6{\AA}, falling to zero at larger separations. There is no evidence that Wr correlates with impact parameter or galaxy luminosity. Our results are consistent with existing scenarios in which cool Mg II-absorbing clouds may be absent near LRGs because of the environment of the galaxies: if LRGs reside in high-mass groups and clusters, either their halos are too hot to retain or accrete cool gas, or the galaxies themselves - which have passively-evolving old stellar populations - do not produce the rates of star formation and outflows of gas necessary to fill their halos with Mg II absorbing clouds. In the rarer cases where Mg II is detected, however, the origin of the absorption is less clear. Absorption may arise from the little cool gas able to reach into cluster halos from the intergalactic medium, or from the few star-forming and/or AGN-like LRGs that are known to exist.Comment: Accepted by ApJ; minor correction

Silsesquioxane polymer as a potential scaffold for laryngeal reconstruction

Cancer, disease and trauma to the larynx and their treatment can lead to permanent loss of structures critical to voice, breathing and swallowing. Engineered partial or total laryngeal replacements would need to match the ambitious specifications of replicating functionality, outer biocompatibility, and permissiveness for an inner mucosal lining. Here we present porous polyhedral oligomeric silsesquioxane-poly(carbonate urea) urethane (POSS-PCUU) as a potential scaffold for engineering laryngeal tissue. Specifically, we employ a precipitation and porogen leaching technique for manufacturing the polymer. The polymer is chemically consistent across all sample types and produces a foam-like scaffold with two distinct topographies and an internal structure composed of nano- and micro-pores. Whilst the highly porous internal structure of the scaffold contributes to the complex tensile behaviour of the polymer, the surface of the scaffold remains largely non-porous. The low number of pores minimise access for cells, although primary fibroblasts and epithelial cells do attach and proliferate on the polymer surface. Our data show that with a change in manufacturing protocol to produce porous polymer surfaces, POSS-PCUU may be a potential candidate for overcoming some of the limitations associated with laryngeal reconstruction and regeneration

Random barrier double-well model for resistive switching in tunnel barriers

The resistive switching phenomenon in MgO-based tunnel junctions is attributed to the effect of charged defects inside the barrier. The presence of electron traps in the MgO barrier, that can be filled and emptied, locally modifies the conductance of the barrier and leads to the resistive switching effects. A double-well model for trapped electrons in MgO is introduced to theoretically describe this phenomenon. Including the statistical distribution of potential barrier heights for these traps leads to a power-law dependence of the resistance as a function of time, under a constant bias voltage. This model also predicts a power-law relation of the hysteresis as a function of the voltage sweep frequency. Experimental transport results strongly support this model and in particular confirm the expected power laws dependencies of resistance. They moreover indicate that the exponent of these power laws varies with temperature as theoretically predicted.Comment: 18 pages, 5 figures, final versio

Z Logic and its Consequences

This paper provides an introduction to the specification language Z from a logical perspective. The possibility of presenting Z in this way is a consequence of a number of joint publications on Z logic that Henson and Reeves have co-written since 1997. We provide an informal as well as formal introduction to Z logic and show how it may be used, and extended, to investigate issues such as equational logic, the logic of preconditions, the issue of monotonicity and both operation and data refinement