Effects of petroleum on estuarine bacteria

The effects of petroleum on the natural microbial flora of a given environment, that is, on the bacteria, yeasts, filamentous fungi, and achlorophyllous algae, have largely been ignored. This paper represents the first recorded investigation of the impact of petroleum on ecologically important groups of bacteria.     

Developing yellowtail kingfish (Seriola lalandi) and hāpuku (Polyprion oxygeneios) for New Zealand aquaculture

Two high value species, yellowtail kingfish (Seriola lalandi) and hāpuku (groper, Polyprion oxygeneios), have been identified as suitable new candidates for New Zealand aquaculture. This paper reviews the research by NIWA and collaborators conducted to test the biological, technological and economic feasibility of farming these two species. NIWA now has the capability to produce sufficient kingfish fingerlings per year to meet the needs of the early stages of an industry. Advances in hāpuku aquaculture have also been significant, from spawning in captivity through to the selection of juveniles for improved growth. Recently, the first spawning of captive hāpuku F1 broodstock and production of F2 eggs, larvae and juveniles was achieved. Although hāpuku larval survival remains variable, the ability to close the life cycle, and the availability of domesticated broodstock, provide a significant step forward and increase the chances of this species being commercially farmed.     

Kepler's Equation and Newton's method

Power series solutions of Kepler's Equation associated with Lagrange, Levi-Civita and Stumpff may be obtained by Newton's method as an algorithm for formal power series.     

The disruption of planetary satellites and the creation of planetary rings

The Voyager spacecraft discovered that small moons orbit within all four observed ring systems coincident with the discovery of narrow and dusty rings around Jupiter, Saturn, Uranus and Neptune. These moons can provide the source for new rings if they are catastrophically disrupted by a comet or large meteoroid impact. This hypothesis for ring origins provides a natural mechanism for the ongoing creation of planetary rings. While it relieves somewhat the problem of explaining the continued existence of rings with apparently short evolutionary lifetimes, it raises the problem of explaining the continued existence of small moons, and the coexistence of moons and rings at comparable locations within the Roche zones of the giant planets. This problem has been studied in some detail recently, and the present work is a review of our current understanding of the processes in satellite disruption that pertain to the creation of planetary rings and the collisional cascade of circumplanetary bodies. Significant progress has been made. Narrow rings are produced by disruption of small moons in numerical simulations, and a self-consistent model of the collisional cascade can explain present-day moon populations. Absolute timescales and initial moon populations remain uncertain due to our poor knowledge of the impactor population and uncertainties in the strength of planetary satellites. More pressing are the qualitative issues that remain to be resolved including the nature of reaccretion of the debris and the origin of Saturn's rings.     

A predator–prey model for moon-triggered clumping in Saturn’s rings

UVIS occultation data show clumping in Saturn’s F ring and at the B ring outer edge, indicating aggregation and disaggregation at these locations that are perturbed by Prometheus and by Mimas. The inferred timescales range from hours to months. Occultation profiles of the edge show wide variability, indicating perturbations by local mass aggregations. Structure near the B ring edge is seen in power spectral analysis at scales 200–2000 m. Similar structure is also seen at the strongest density waves, with significance increasing with resonance strength. For the B ring outer edge, the strongest structure is seen at longitudes 90° and 270° relative to Mimas. This indicates a direct relation between the moon and the ring clumping. We propose that the collective behavior of the ring particles resembles a predator–prey system: the mean aggregate size is the prey, which feeds the velocity dispersion; conversely, increasing dispersion breaks up the aggregates. Moons may trigger clumping by streamline crowding, which reduces the relative velocity, leading to more aggregation and more clumping. Disaggregation may follow from disruptive collisions or tidal shedding as the clumps stir the relative velocity. For realistic values of the parameters this yields a limit cycle behavior, as for the ecology of foxes and hares or the “boom-bust” economic cycle. Solving for the long-term behavior of this forced system gives a periodic response at the perturbing frequency, with a phase lag roughly consistent with the UVIS occultation measurements. We conclude that the agitation by the moons in the F ring and at the B ring outer edge drives aggregation and disaggregation in the forcing frame. This agitation of the ring material may also allow fortuitous formation of solid objects from the temporary clumps, via stochastic processes like compaction, adhesion, sintering or reorganization that drives the denser parts of the aggregate to the center or ejects the lighter elements. Any of these more persistent objects would then orbit at the Kepler rate. We would also expect the formation of clumps and some more permanent objects at the other perturbed regions in the rings… including satellite resonances, shepherded ring edges, and near embedded objects like Pan and Daphnis (where the aggregation/disaggregation cycles are forced similar to Prometheus forcing of the F ring).     

Ejecta from impacts at 0.2-2.3 m/s in low gravity

Collisions between planetary ring particles and in some protoplanetary disk environments occur at speeds below 10 m/s. The particles involved in these low-velocity collisions have negligible gravity and may be made of or coated with smaller dust grains and aggregates. We undertook microgravity impact experiments to better understand the dissipation of energy and production of ejecta in these collisions. Here we report the results of impact experiments of solid projectiles into beds of granular material at impact velocities from 0.2 to 2.3 m/s performed under near-weightless conditions on the NASA KC-135 Weightless Wonder V. Impactors of various densities and radii of 1 and 2 cm were launched into targets of quartz sand, JSC-1 lunar regolith simulant, and JSC-Mars-1 martian regolith simulant. Most impacts were at normal or near-normal incidence angles, though some impacts were at oblique angles. Oblique impacts led to much higher ejection velocities and ejecta masses than normal impacts. For normal incidence impacts, characteristic ejecta velocities increase with impactor kinetic energy, KE, as approximately KE^0.5. Ejecta masses could not be measured accurately due to the nature of the experiment, but qualitatively also increased with impactor kinetic energy. Some experiments were near the threshold velocity of 0.2 m/s identified in previous microgravity impact experiments as the minimum velocity needed to produce ejecta [Colwell, J.E., 2003. Icarus 164, 188-196], and the experimental scatter is large at these low speeds in the airplane experiment. A more precise exploration of the transition from low-ejecta-mass impacts to high-ejecta-mass impacts requires a longer and smoother period of reduced gravity. Coefficient of restitution measurements are not possible due to the varying acceleration of the airplane throughout the experiment.     

Quaternary hemipelagic sedimentation in the basins flanking the Solomon Islands volcanic arc

Quaternary sediments in the Woodlark Basin and New Georgia Sound, adjacent to the Solomon Islands volcanic arc, are hemipelagic. They consist of mixtures of clay minerals, calcareous plankton (foraminifera, coccoliths, and pteropods), and sand- and silt-sized volcanic debris. Variations in sediment composition are related primarily to distance from land (the source of volcanic components), water depth (because of the Aragonite and Calcite Compensation Depths), and bathymetric isolation. Much of the sedimentary debris is delivered to the basin by turbidity currents and other mass movements; little material is supplied by ash fall. Sedimentation rates appear to exceed 3 cm/1,000 years in New Georgia Sound, and range from 2 to 4.5 cm/1,000 years in the Woodlark Basin.     

Density waves in Cassini UVIS stellar occultations: 1. The Cassini Division

We analyze density waves in the Cassini Division of Saturn's rings revealed by multiple stellar occultations by Saturn's rings observed with the Cassini Ultraviolet Imaging Spectrograph. The dispersion and damping of density waves provide information on the local ring surface mass density and viscosity. Several waves in the Cassini Division are on gradients in the background optical depth, and we find that the dispersion of the wave reflects a change in the underlying surface mass density. We find that over most of the Cassini Division the ring opacity (the ratio of optical depth to surface mass density) is nearly constant and is ∼5 times higher than the opacity in the A ring where most density waves are found. However, the Cassini Division ramp, a 1100-km-wide, nearly featureless region of low optical depth that connects the Cassini Division to the inner edge of the A ring, has an opacity like that of the A ring and significantly less than that in the rest of the Cassini Division. This is consistent with particles in the ramp originating in the A ring and being transported into the Cassini Division through ballistic transport processes. Damping of the waves in the Cassini Division suggests a vertical thickness of 3–6 m. Using a mean opacity of 0.1 cm²/g we find the mass of the Cassini Division, excluding the ramp, is 3.1×¹⁰¹⁶ kg while the mass of the Cassini Division ramp, with an opacity of 0.015 cm²/g, is 1.1×¹⁰¹⁷ kg. Assuming a power-law size distribution for the ring particles, the larger opacity of the main Cassini Division is consistent with the largest ring particles there being ∼5 times smaller than the largest particles in the ramp and A ring.     

Data-moderate assessments of Cape monkfish Lophius vomerinus and west coast sole Austroglossus microlepis in Namibian waters

There is global interest in providing scientific advice on optimal harvesting of all commercially exploited fish stocks. Nevertheless, many commercially important stocks lack analytical assessments. Therefore, we evaluate a data-moderate stock assessment method: the stochastic surplus production model in continuous time (SPiCT). The method was applied to two Namibian stocks: (i) the data-rich Cape monkfish Lophius vomerinus, where results are compared to a new data-rich assessment using a state–space assessment model (SAM); and (ii) the data-moderate west coast sole Austroglossus microlepis, which is an important bycatch species in the Cape monkfish fishery, but currently unassessed. The information available to the data-moderate assessment is total commercial catch, commercial catch per unit effort (CPUE), and survey CPUE. SPiCT and SAM gave largely consistent estimates of relative fishing mortality (F/F_MSY) and relative exploitable biomass (B/B_MSY) for the Cape monkfish stock, although with some discrepancies. Differences in the biomass estimates between the two assessments suggest that further investigation is required to understand the cause, and that some caution is necessary when considering the biomass of the stock. SPiCT shows that the west coast sole may be overexploited, although the confidence bounds were too wide for a firm conclusion. Similarity in the estimates of F/F_MSY for Cape monkfish in recent years, using SPiCT relative to SAM, likewise indicates the suitability of SPiCT for managing west coast sole.     

Early Carboniferous blueschist facies metamorphism in metapelites of the West Sudetes (Northern Saxothuringian Domain,Bohemian Massif)

The metamorphic evolution of micaschists in the north‐eastern part of the Saxothuringian Domain in the Central European Variscides is characterized by the early high‐pressure M1 assemblage with chloritoid in cores of large garnet porphyroblasts and a Grt–Chl–Phe–Qtz ± Pg M2 assemblage in the matrix. Minerals of the M1–M2 stage were overprinted by the low‐pressure M3 assemblage Ab–Chl–Ms–Qtz ± Ep. Samples with the best‐preserved M1–M2 mineralogy mostly appear in domains dominated by the earlier D1 deformation phase and are only weakly affected by subsequent D2 overprint. Thermodynamic modelling suggests that mineral assemblages record peak‐pressure conditions of ≥18–19 kbar at 460–520 °C (M1) followed by isothermal decompression 10.5–13.5 kbar (M2) and final decompression to <8.5 kbar and <480 °C (M3). The calculated peak P–T conditions indicate a high‐pressure/low‐temperature apparent thermal gradient of ～7–7.5 °C km^?1. Laser ablation inductively coupled plasma mass spectrometry isotopic dating and electron microprobe chemical dating of monazite from the M1–M2 mineral assemblages give ages of 330 ± 10 and 328 ± 6 Ma, respectively, which are interpreted as the timing of a peak pressure to early decompression stage. The observed metamorphic record and timing of metamorphism in the studied metapelites show striking similarities with the evolution of the central and south‐western parts of the Saxothuringian Domain and suggest a common tectonic evolution along the entire eastern flank of the Saxothuringian Domain during the Devonian–Carboniferous periods.