Environmental estrogens: dose–response relationships for vitellogenin formation and reproductive toxicity in male rainbow trout

The appearance of the egg-yolk protein vitellogenin (Vg) in plasma of male fish is a sensitive indicator of exposure to estrogenic compounds. We have been studying the kinetics of Vg formation and excretion in rainbow trout with a goal towards developing an integrated pharmacokinetic–pharmcodynamic (PK–PD) model to quantitatively relate cumulative estrogenic exposure of fish to the expression and appearance of Vg in plasma. We administered graded doses of ethynylestradiol (EE2), o,p-DDT, DDD and DDE and octylphenol to male rainbow trout via a dorsal aortic cannula which allowed repetitive blood sampling from individual fish for up to 48 days after injection. The plasma concentrations of the xenobiotics and Vg were simultaneously quantified using ELISA and GC–MS or GC–ECD. In separate experiments, sexually mature trout were exposed to graded water concentrations of EE2 for 3 months and various parameters indicative of the functional status of the male reproductive system determined. These parameters included tissue-somatic indices, histopathological evaluation, spermatocrit, sperm motility (quantified using computer-assisted-motion analysis) and viability of semen based on fertilization assays using eggs harvested from untreated trout. Results from fertilization assays indicated that 12 week exposure to EE2 concentrations of 10 and 100 ng/l caused a 50% reduction in the fertilization rate of semen harvested from exposed trout. PK–PD modeling strategies proved valuable tools for linking chemical exposures to Vg formation.     

A dual sensor device to estimate fluid flow velocity at diffuse hydrothermal vents

Numerous attempts have been made over the last thirty years to estimate fluid flow rates at hydrothermal vents, either at the exit of black smoker chimneys or within diffuse flow areas. In this study, we combine two methods to accurately estimate fluid flow velocities at diffuse flow areas. While the first method uses a hot film anemometer that performs high-frequency measurements, the second allows a relatively rapid assessment of fluid flow velocity through video imagery and provides in situ data to calibrate the sensor. Measurements of flow velocities on hydrothermal diffuse flow areas were obtained on the Mid-Atlantic Ridge (MAR). They range from 1.1 to 4.9 mm/s at the substratum level, in low-temperature (4.5–16.4 °C) diffuse flow areas from the Tour Eiffel sulfide edifice. A strong correlation was observed between fluid flow velocities and temperature, supporting the possible use of temperature as a proxy to estimate the flow rates in diffuse flow areas where such a simple linear flow/temperature relation is shown to dominate.     

First record of stereospondyls (Tetrapoda,Temnospondyli) in the Upper Triassic of Southern Brazil

Stereospondyls survived the Permo-Triassic extinctions in a refuge probably located in the landmass that nowadays comprises Australia. Subsequently, they radiated to other parts of Pangaea, reaching their highest distribution and diversification during the Early Triassic. An incomplete interclavicle from the Caturrita Formation represents their first record in the Upper Triassic of Brazil. Previously, Upper Triassic South American stereospondyls were restricted to Argentina. This new record reinforces a former hypothesis that suggests the presence of a more diverse stereospondyl fauna in South America during the Late Triassic than previously assumed. Additionally, the presence of a stereospondyl and a phytosaur in the Caturrita Formation reinforces the hypothesis of a change to more humid climatic conditions in the Paraná Basin during the Upper Triassic. The record of Early Triassic stereospondyls in South America suggests that they first colonized Brazil and/or Uruguay, spreading from South Africa during the Early Triassic, subsequently reaching Argentina. Up till now, there is no record of Middle Triassic stereospondyls in either Argentina and Brazil, probably due to either taphonomic bias or insufficient prospecting. Despite the lack of direct evidence, one should not dismiss an earlier stereospondyl colonization of Argentina still during the Early or Middle Triassic.     

Stochastic simulation model for tropical cyclone tracks,with special emphasis on landfall behavior

We consider a spatial stochastic model for the simulation of tropical cyclone tracks, which has recently been introduced. Cyclone tracks are represented as labeled polygonal lines, which are described by the movement directions, translational speeds, and wind speeds of the cyclones in regular 6-h intervals. In the present paper, we compare return levels for wind speeds of historically observed cyclone tracks with those generated by the simulator, where a mismatch is shown for most of the considered coastal regions. To adjust this discrepancy, we develop a stochastic algorithm for acceptance and rejection of simulated cyclone tracks with landfall. It is based on the fact that the locations, translational speeds, and wind speeds of cyclones at landfall constitute three-dimensional Poisson point processes, which are a basic model type in stochastic geometry. Due to that, a well-known thinning property of Poisson processes can be applied. This means that to each simulated cyclone, an acceptance probability is assigned, which is higher for cyclones with suitable landfall characteristics and lower for implausible ones. More intuitively, the algorithm comprises the simulation of a more comprehensive cyclone event set than needed and the random selection of those tracks that best match historical observations at landfall. A particular advantage of our algorithm is its applicability to multiple landfalls, i.e., to cyclones that successively make landfall at two geographically distinct coastlines, which is the most relevant case in applications. It turns out that the extended simulator provides a much better accordance between landfall characteristics of historical and simulated cyclone tracks.     

Itqiy: A study of noble gases and oxygen isotopes including its terrestrial age and a comparison with Zakłodzie

Abstract— We report noble gas, oxygen isotope, ¹⁴C and ¹⁰Be data of Itqiy as well as noble gas, ¹⁴C and ¹⁰Be results for Zak?odzie. Both samples have been recently classified as anomalous enstatite meteorites and have been compared in terms of their mineralogy and chemical composition. The composition of enstatite and kamacite and the occurrence of specific sulfide phases in Itqiy indicate it formed under similar reducing conditions to those postulated for enstatite chondrites. The new results now seem to point at a direct spatial link. The noble gas record of Itqiy exhibits the presence of a trapped subsolar component, which is diagnostic for petrologic types 4–6 among enstatite chondrites. The concentration of radiogenic ⁴He is very low in Itqiy and indicates a recent thermal event. Its ²¹Ne cosmic‐ray exposure age is 30.1 ± 3.0 Ma and matches the most common age range of enstatite chondrites (mostly EL6 chondrites) but not that of Zak?odzie. Itqiy's isotopic composition of oxygen is in good agreement with that observed in Zak?odzie as well as those found in enstatite meteorites suggesting an origin from a common oxygen pool. The noble gas results, on the other hand, give reason to believe that the origin and evolution of Itqiy and Zak?odzie are not directly connected. Itqiy's terrestrial age of 5800 ± 500 years sheds crucial light on the uncertain circumstances of its recovery and proves that Itqiy is not a modern fall, whereas the ¹⁴C results from Zak?odzie suggest it hit Earth only recently.     

Noble gases in enstatite chondrites II: The trapped component

Abstract— The trapped noble gas record of 57 enstatite chondrites (E chondrites) has been investigated. Basically, two different gas patterns have been identified dependent on the petrologic type. All E chondrites of type 4 to 6 show a mixture of trapped common chondritic rare gases (Q) and a subsolar component (range of elemental ratios for E4–6 chondrites: ³⁶Ar/¹³²Xe = 582 ± 270 and ³⁶Ar/⁸⁴Kr = 242 ± 88). E3 chondrites usually contain Q gases, but also a composition with lower ³⁶Ar/¹³²Xe and ³⁶Ar/⁸⁴Kr ratios, which we call sub‐Q (³⁶Ar/¹³²Xe = 37.0 ± 18.0 and ³⁶Ar/⁸⁴Kr = 41.7 ± 18.1). The presence of either the subsolar or the sub‐Q signature in particular petrologic types cannot be readily explained by parent body metamorphism as postulated for ordinary chondrites. We therefore present a different model that can explain the bimodal distribution and composition of trapped heavy noble gases in E chondrites. Trapped solar noble gases have been observed only in some E3 chondrites. About 30% of each group, EH3 and EL3 chondrites, amounting to 9% of all analyzed E chondrites show the solar signature. Notably, only one of those meteorites has been explicitly described as a regolith breccia.     

The irradiation history of the Ghubara (L5) regolith breccia

Abstract— We measured cosmic‐ray products—noble gases, radionuclides, thermoluminescence, and nuclear tracks—and trace element contents and mineralogy of samples of three orthogonal and mutually intersecting cores (41–46 cm long) of a 101.6 kg Ghubara individual (1958,805) at The Natural History Museum, London. The xenoliths, like the host, have high concentrations of trapped solar gases and are heavily shocked. While contents of noble gases and degree of shock‐loading in this individual and three others differ somewhat, the data indicate that Ghubara is a two‐generation regolith breccia. Contents of cosmogenic ²⁶Al and ¹⁰Be and low track densities indicate that the Ghubara individuals were located more than 15 cm below the surface of an 85 cm meteoroid. Because of its large size, Ghubara's cosmic‐ray exposure age is poorly defined to be 15–20 Ma from cosmogenic nuclides. Ghubara's terrestrial age, based on ¹⁴C data, is 2–3 ka. Not only is Ghubara the first known case of a two‐generation regolith breccia on the macroscale, it also has a complicated thermal and irradiation history.     

The geology of the Viking Lander 2 site revisited

Reevaluating the geologic history of the prior Mars landing sites provides important ground truth for recent and ongoing orbital missions. At the Viking 2 Lander (VL2) site, topographic measurements of relict landforms indicate that at least 100 m of sedimentary mantle material has been stripped away. The observed paucity of impact craters <100 m in diameter suggests that resurfacing processes (likely in the form of the recent deposition and removal of thin 1-10 m mantle layers) continue up to the present. A dearth of craters in the 100-500 m diameter range, however, also necessitates erosion of a thicker mantle layer. Partially inverted chains of secondary craters from nearby Mie Crater indicate that the mantle was already in place when the impact occurred. The density of craters superposed on Mie ejecta is consistent with a Late Hesperian age and provides a minimum age constraint for the mantle's emplacement. The thermophysical properties of the surface around VL2 as observed with Thermal Emission Imaging System (THEMIS) data indicate that the landing site occurs in an intracrater region that may typify mid to high northern latitude sites. Elevated thermal inertias of a pedestal crater superposed atop a larger pedestal crater suggest that rocky or indurated material can be created by impacts into sedimentary targets. Rock abundances at VL2 are consistent with the addition of impact-emplaced material from the missing small impact crater population documented in this study. Thus, the VL2 site may be a reasonable proxy for the landscape expected at the upcoming Phoenix Lander site.     

The Deep Impact oblique impact cratering experiment

The Deep Impact probe collided with 9P Tempel 1 at an angle of about 30° from the horizontal. This impact angle produced an evolving ejecta flow field very similar to much smaller scale oblique-impact experiments in porous particulate targets in the laboratory. Similar features and phenomena include a decoupled vapor/dust plume at the earliest times, a pronounced downrange bias of the ejecta, an uprange “zone of avoidance” (ZoA), heart-shaped ejecta ray system (cardioid pattern), and a conical (but asymmetric) ejecta curtain. Departures from nominal cratering evolution, however, provide clues on the nature of the impact target. These departures include: fainter than expected flash at first contact, delayed emergence of the self-luminous vapor/dust plume, uprange-directed plume, narrow early-time uprange ray followed by a late-stage uprange plume, persistence of ejecta asymmetries (and the uprange ZoA) throughout the approach sequence, emergence of a downrange ZoA at late times, detachment of uprange curved rays, very long lasting non-radial ejecta rays, and high-angle ejecta plume lasting over the entire encounter. The first second of crater formation most closely resembles the consequences of a highly porous target, while later evolution indicates that the target may be layered as well. Experiments also reveal that impacts into highly porous targets produce a vapor/dust plume directed back up the incoming trajectory. This uprange plume is attributed to cavitation within a narrow penetration funnel. The observed lateral expansion speed of the initial vapor plume downrange provides an estimate for the total vaporized mass equal to ∼5mp (projectile masses) of water ice or 6mp of CO₂. The downrange plume speed is consistent with the gas expansion added to the downrange horizontal component of the DI probe. Based on high-speed spectroscopy of experimental impacts, the observed delay in brightening of the DI plume may be the result of delayed condensation of carbon, in addition to silicates. Observed molecular species in the initial self-luminous vapor plume likely represent recombination products from completely dissociated target materials. The crater produced by the impact can be estimated from Earth-based observations of total ejected mass to be 130-220 m in diameter. This size range is consistent with a 220 m-diameter circular feature at the point of impact visible in highly processed, deconvolved HRI images. The final crater, however, may resemble an inverted sombrero-hat, with a deep central pit surrounded by a shallow excavation crater. Excavated distal material observed from the Earth was likely from the upper few meters contrasted with ballistic ejecta observed from the DI flyby, which included deep materials (10-30 m) within the diffuse plume above the crater and shallower (5-10 m) materials within the ejecta curtain.