Miocene stable isotopic stratigraphy and magnetostratigraphy of Buff Bay, Jamaica

Previously reported biostratigraphic relationships from middle-upper Miocene sections exposed near Buff Bay, Jamaica (18°N, tropical bioprovince), differ from the subtropical North Atlantic (Sites 563 and 558). Time scales for this interval rely on correlations established at these subtropical sites, and the differences with the tropical section have implications to global correlations. Planktonic foraminiferal Zones N13 and N15 are thick at Buff Bay but are virtually absent at Sites 563 and 558; nannofossil Zone NN9 is associated with Zone N15 and uppermost Zone N14 at Buff Bay but is associated with Zone N16 at the other sites. Magnetostratigraphic data presented here further complicate the interpretation: Zone NN9 is associated with a thick normal magnetozone at Sites 563 and 558; at Buff Bay, it is associated with a thick reversed magnetozone. Although a secondary magnetization at Buff Bay makes it difficult to identify confidently Miocene normal magnetozones, the thick reversed magnetozone most likely represents the paleomagnetic field and correlates with Chron C5r. The magnetobiostratigraphic relationships require either diachrony of taxa or two mutually exclusive hiatuses in Jamaica and the North Atlantic. We address this problem by analyzing benthic foraminiferal δ^18O and δ^13C from the Buff Bay section. These isotopic data allow us to evaluate three hypotheses that reconcile the magneto-, bio-, and isotopic stratigraphic data and conclude that the first and last occurrences of five taxa were diachronous by ~0.3-0.5 m.y. between tropical and subtropical locations. This requires revised age estimates for late middle to early late Miocene biostratigraphic datum levels. We suggest that the ranges of several taxa are useful for endemic tropical or subtropical zonations, but correlations between the low and midlatitudes were affected by an increase in latitudinal thermal gradients during the late middle Miocene. However, we admit that further studies are needed before this issue is resolved

Pass-through core measurements of magnetic susceptibility and natural gamma ray, New Jersey Coastal Plain

We measured magnetic susceptibility (MS) and core gamma radiation (CGR) on 3162 ft (963.9 m) of core recovered by the New Jersey Coastal Plain Drilling Project (Ocean Drilling Program Leg 150X) at Island Beach, Atlantic City, and Cape May, New Jersey. Integration of core lithology, core/log (MS and CGR), and downhole gamma-ray (DGR) log studies have (1) documented the core/log expression of previously determined unconformities; (2) shown that MS is a proxy for glauconite percent in the New Jersey Coastal Plain; (3) illustrated a major change in sedimentation from shelfal glauconite evidenced by very high MS values to deltaic deposition with low MS values in the earliest Miocene (ca. 22 Ma); (4) shown that comparison of MS and CGR with DGR can be used to resolve discrepancies in depth between downhole logs and cores; and (5) shown that the CGR detects some zones noted in the lithology (e.g., phosphate rich zones) that are not resolved in the DGR

Electron Paramagnetic Resonance and Optical Absorption Study of Acceptors in CdSiP\u3csub\u3e2\u3c/sub\u3e Crystals

Cadmium silicon diphosphide (CdSiP2) is a nonlinear material often used in optical parametric oscillators (OPOs) to produce tunable laser output in the mid-infrared. Absorption bands associated with donors and acceptors may overlap the pump wavelength and adversely affect the performance of these OPOs. In the present investigation, electron paramagnetic resonance (EPR) is used to identify two unintentionally present acceptors in large CdSiP2 crystals. These are an intrinsic silicon-on-phosphorus antisite and a copper impurity substituting for cadmium. When exposed to 633 µm laser light at temperatures near or below 80 K, they convert to their neutral paramagnetic charge states (Si0P and Cu0Cd) and can be monitored with EPR. The corresponding donor serving as the electron trap is the silicon-on-cadmium antisite (Si2+Cd before illumination and Si+Cd after illumination). Removing the 633 µm light and warming the crystal above 90 K quickly destroys the EPR signals from both acceptors and the associated donor. Broad optical absorption bands peaking near 0.8 and 1.4 μm are also produced at low temperature by the 633 µm light. These absorption bands are associated with the Si0P and Cu0Cd acceptors

QMCPACK: Advances in the development, efficiency, and application of auxiliary field and real-space variational and diffusion Quantum Monte Carlo

We review recent advances in the capabilities of the open source ab initio Quantum Monte Carlo (QMC) package QMCPACK and the workflow tool Nexus used for greater efficiency and reproducibility. The auxiliary field QMC (AFQMC) implementation has been greatly expanded to include k-point symmetries, tensor-hypercontraction, and accelerated graphical processing unit (GPU) support. These scaling and memory reductions greatly increase the number of orbitals that can practically be included in AFQMC calculations, increasing accuracy. Advances in real space methods include techniques for accurate computation of band gaps and for systematically improving the nodal surface of ground state wavefunctions. Results of these calculations can be used to validate application of more approximate electronic structure methods including GW and density functional based techniques. To provide an improved foundation for these calculations we utilize a new set of correlation-consistent effective core potentials (pseudopotentials) that are more accurate than previous sets; these can also be applied in quantum-chemical and other many-body applications, not only QMC. These advances increase the efficiency, accuracy, and range of properties that can be studied in both molecules and materials with QMC and QMCPACK

Interpatient heterogeneity in expression of CYP3A4 and CYP3A5 in small bowel: Lack of prediction by the erythromycin breath test

The CYP3A subfamily of cytochromes P450 metabolize many medications and environmental contaminants. CYP3A4 and, in 25% of patients, CYP3A5 seem to be the major CYP3A genes expressed in adult liver. Hepatic levels of CYP3A4 can be estimated by the erythromycin breath test and vary at least 10-fold among patients. CYP3A4 has also been shown to be present in small bowel where it is responsible for significant "first-pass" metabolism of orally administered substrates. However, it is not known whether there is significant interindividual variability in the intestinal expression of CYP3A4, or whether the liver and intestinal catalytic activities of CYP3A4 correlate within an individual. It is also not known whether CYP3A5 is expressed in the small intestine. To address these questions, we administered the erythromycin breath test to 20 patients and obtained biopsies from their small bowel. There was a 6-fold variation in CYP3A catalytic activity (midazolam hydroxylation), an 11-fold variation in CYP3A4 protein content, and an 8-fold variation in CYP3A4 mRNA content in intestinal biopsies. There was an excellent correlation between intestinal CYP3A4 protein level and catalytic activity (r = 0.86; p = 0.0001); however, neither parameter significantly correlated with hepatic CYP3A4 activity as measured by the erythromycin breath test result (r = 0.27; p = 0.24 and r = 0.33; p = 0.15, respectively). We also found that CYP3A5 protein was readily detectable in biopsies from 14 (70%) of the patients, indicating that CYP3A5 is commonly expressed in human small intestine

Sonar-induced pressure fields in a post-mortem common dolphin

Author Posting. © Acoustical Society of America, 2012. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 131 (2012): 1595-1604, doi:10.1121/1.3675005.Potential physical effects of sonar transmissions on marine mammals were investigated by measuring pressure fields induced in a 119-kg, 211-cm-long, young adult male common dolphin (Delphinus delphis) cadaver. The specimen was instrumented with tourmaline acoustic pressure gauges used as receiving sensors. Gauge implantation near critical tissues was guided by intraoperative, high-resolution, computerized tomography (CT) scanning. Instrumented structures included the melon, nares, ear, thoracic wall, lungs, epaxial muscle, and lower abdomen. The specimen was suspended from a frame equipped with a standard 50.8-mm-diameter spherical transducer used as the acoustic source and additional receiving sensors to monitor the transmitted and external, scattered field. Following immersion, the transducer transmitted pulsed sinusoidal signals at 5, 7, and 10 kHz. Quantitative internal pressure fields are reported for all cases except those in which the gauge failed or no received signal was detected. A full necropsy was performed immediately after the experiment to examine instrumented areas and all major organs. No lesions attributable to acoustic transmissions were found, consistent with the low source level and source-receiver distances.Work supported by NOPP through ONR Grant No. N000140710992. Work at CSI additionally supported by ONR Grant No. N000140811231