Discriminating cool-water from warm-water carbonates and their diagenetic environments using element geochemistry: the Oligocene Tikorangi Formation (Taranaki Basin) and the dolomite effect

Fields portrayed within bivariate element plots have been used to distinguish between carbonates formed in warm- (tropical) water and cool- (temperate) water depositional settings. Here, element concentrations (Ca, Mg, Sr, Na, Fe, and Mn) have been determined for the carbonate fraction of bulk samples from the late Oligocene Tikorangi Formation, a subsurface, mixed dolomite-calcite, cool-water limestone sequence in Taranaki Basin, New Zealand. While the occurrence of dolomite is rare in New Zealand Cenozoic carbonates, and in cool-water carbonates more generally, the dolomite in the Tikorangi carbonates is shown to have a dramatic effect on the "traditional" positioning of cool-water limestone fields within bivariate element plots. Rare undolomitised, wholly calcitic carbonate samples in the Tikorangi Formation have the following average composition: Mg 2800 ppm; Ca 319 100 ppm; Na 800 ppm; Fe 6300 ppm; Sr 2400 ppm; and Mn 300 ppm. Tikorangi Formation dolomite-rich samples (>15% dolomite) have average values of: Mg 53 400 ppm; Ca 290 400 ppm; Na 4700 ppm; Fe 28 100 ppm; Sr 5400 ppm; and Mn 500 ppm. Element-element plots for dolomite-bearing samples show elevated Mg, Na, and Sr values compared with most other low-Mg calcite New Zealand Cenozoic limestones. The increased trace element contents are directly attributable to the trace element-enriched nature of the burial-derived dolomites, termed here the "dolomite effect". Fe levels in the Tikorangi Formation carbonates far exceed both modern and ancient cool-water and warm-water analogues, while Sr values are also higher than those in modern Tasmanian cool-water carbonates, and approach modern Bahaman warm-water carbonate values. Trace element data used in conjunction with more traditional petrographic data have aided in the diagenetic interpretation of the carbonate-dominated Tikorangi sequence. The geochemical results have been particularly useful for providing more definitive evidence for deep burial dolomitisation of the deposits under the influence of marine-modified pore fluids

Entanglement, fidelity, and quantum-classical correlations with an atom walking in a quantized cavity field

Stability and instability of quantum evolution are studied in the interaction between a two-level atom with photon recoil and a quantized field mode in an ideal cavity, the basic model of cavity quantum electrodynamics (QED). It is shown that the Jaynes-Cummings dynamics can be unstable in the regime of chaotic walking of the atomic center-of-mass in the quantized field of a standing wave in the absence of any kind of interaction with environment. This kind of quantum instability manifests itself in strong variations of reduced quantum purity and entropy, correlating with the respective classical Lyapunov exponent, and in exponential sensitivity of fidelity of quantum states to small variations in the atom-field detuning. The connection between quantum entanglement and fidelity and the center-of-mass motion is clarified analytically and numerically for a few regimes of that motion. The results are illustrated with two specific initial field states: the Fock and coherent ones. Numerical experiments demonstrate various manifestations of the quantum-classical correspondence, including dynamical chaos and fractals, which can be, in principle, observed in real experiments with atoms and photons in high finesse cavities

Skill assessment of multiple hypoxia models in Chesapeake Bay and implications for management decisions

The Chesapeake Bay Program (CBP) has used their coupled watershed-water quality modeling system to develop a set of Total Maximum Daily Loads (TMDLs) for nutrients and sediment in an effort to reduce eutrophication impacts which include decreasing the seasonal occurrence of hypoxia within the Bay. The CBP is now considering the use of a multiple model approach to enhance the confidence in their model projections and to better define uncertainty. This study statistically compares the CBP regulatory model with multiple implementations of the Regional Ocean Modeling System (ROMS) in terms of skill in reproducing monthly profiles of hydrodynamics, nutrients, chlorophyll and dissolved oxygen at ~30 stations throughout the Bay. Preliminary results show that although all the models substantially underestimate stratification throughout the Bay, they all have significant skill in reproducing the mean and seasonal variability of bottom dissolved oxygen. This study demonstrates that multiple community models can be used together to provide independent confidence bounds for management decisions based on CBP model results

A three-dimensional study of reconnection, current sheets and jets resulting from magnetic flux emergence in the Sun

We present the results of a set of three-dimensional numerical simulations of magnetic flux emergence from below the photosphere into the corona that include a uniform and horizontal coronal magnetic field mimicking a pre-existing large-scale coronal magnetic system. Cases with different relative orientations of the upcoming and coronal fields are studied. Upon contact, a concentrated current sheet with the shape of an arch or bridge is formed at the interface which marks the positions of maximum jump in the field vector between the two systems. Relative angles above 90 degrees yield abundant magnetic reconnection and plasma heating. The reconnection is seen to be intrisincally three-dimensional in nature, except at singular positions along the current sheet. It drives collimated high-speed and high-temperature outflows only a short distance from the reconnection site that propagate along the ambient magnetic field lines as jets. Due to the low plasma density in the corona, these jets may propagate over large distances and, therefore help distribute high-density and high-temperature plasma along these newly reconnected field lines. The experiments permit to discern and visualize the three-dimensional shape and relative position of the upcoming plasma hill, high-speed jets and subphotospheric flux system. As a result of the reconnection, magnetic field lines from the magnetized plasma below the surface end up as coronal field lines, thus causing a profound change in the connectivity of the magnetic regions in the corona. The experiments presented here thus yield a number of features repeatedly observed with the TRACE satellite and the YOHKOH-SXT detector, like the establishment of connectivity between emergent and pre-existing active regions, local heating and high-velocity outflows.Comment: 13 pages, 7 figures, inpress ApJ

Two-dimensional limit of exchange-correlation energy functional approximations in density functional theory

We investigate the behavior of three-dimensional (3D) exchange-correlation energy functional approximations of density functional theory in anisotropic systems with two-dimensional (2D) character. Using two simple models, quasi-2D electron gas and two-electron quantum dot, we show a {\it fundamental limitation} of the local density approximation (LDA), and its semi-local extensions, generalized gradient approximation (GGA) and meta-GGA (MGGA), the most widely used forms of which are worse than the LDA in the strong 2D limit. The origin of these shortcomings is in the inability of the local (LDA) and semi-local (GGA/MGGA) approximations to describe systems with 2D character in which the nature of the exchange-correlation hole is very nonlocal. Nonlocal functionals provide an alternative approach, and explicitly the average density approximation (ADA) is shown to be remarkably accurate for the quasi-2D electron gas system. Our study is not only relevant for understanding of the functionals but also practical applications to semiconductor quantum structures and materials such as graphite and metal surfaces. We also comment on the implication of our findings to the practical device simulations based on the (semi-)local density functional method.Comment: 21 pages including 9 figures, to be published in Phys. Rev.

Detection of Central Visual Field Defects in Early Glaucomatous Eyes: comparison of Humphrey and Octopus perimetry

Purpose: To compare the detection rate of central visual field defect (CVFD) between the 30-degree Octopus G1 program (Dynamic strategy) and the HFA 10–2 SITA-Standard test in early glaucoma eyes not showing any CVFD on the HFA 24–2 SITA-Standard test. Methods: One eye of 41 early glaucoma patients without CVFD in the central 10 on HFA 24–2 test was tested with both the HFA 10–2 test and the Octopus G1 program 15 minutes apart, in random order. The primary outcome measure was the comparison of CVFD detection rates. Secondary outcome measures comprised the agreement in detecting CVFD, and the comparison of test durations and the numbers of depressed test points outside the central 10-degree area between the HFA 24–2 test and the Octopus G1 program. Results: The mean age of the population was 65.2±10.1 years, and the mean deviation with HFA 24–2 was -3.26±2.6 dB. The mean test duration was not significantly different between the tests (p = 0.13). A CVFD was present in 33 (80.4%) HFA 10–2 test and in 23 (56.0%) Octopus G1 tests (p = 0.002). The overall agreement between the HFA 10–2 and Octopus G1 examinations in classifying eyes as having or not having CVFD was moderate (Cohen’s kappa 0.47). The Octopus G1 program showed 69.6% sensitivity and 100% specificity to detect CVFD in eyes where the HFA 10–2 test revealed a CVFD. The number of depressed test points (p<5%) outside the central 10 area detected with the Octopus G1 program (19.68±10.6) was significantly higher than that detected with the HFA 24–2 program (11.95±5.5, p<0.001). Conclusion: Both HFA 10–2 and Octopus G1programs showed CVFD not present at HFA 24–2 test although the agreement was moderate. The use of a single Octopus G1 examination may represent a practical compromise for the assessment of both central and peripheral visual field up to 30 eccentricity without any additional testing and increasing the total investigation time

Quantum Communication with Phantom Photons

We show that quantum information may be transferred between atoms in different locations by using ``phantom photons'': the atoms are coupled through electromagnetic fields, but the corresponding field modes do not have to be fully populated. In the case where atoms are placed inside optical cavities, errors in quantum information processing due to photon absorption inside the cavity are diminished in this way. This effect persists up to intercavity distances of about a meter for the current levels of cavity losses, and may be useful for distributed quantum computing.Comment: 6 pages RevTex, 4 eps figures included. Revised calculation with more details about mode structure calculation and the introduction of losse

Coherent dynamics of Bose-Einstein condensates in high-finesse optical cavities

We study the mutual interaction of a Bose-Einstein condensed gas with a single mode of a high-finesse optical cavity. We show how the cavity transmission reflects condensate properties and calculate the self-consistent intra-cavity light field and condensate evolution. Solving the coupled condensate-cavity equations we find that while falling through the cavity, the condensate is adiabatically transfered into the ground state of the periodic optical potential. This allows time dependent non-destructive measurements on Bose-Einstein condensates with intriguing prospects for subsequent controlled manipulation.Comment: 5 pages, 5 figures; revised version: added reference