Comparison and history of Polydora websteri and P. haswelli (Polychaeta: Spionidae) as mud-blister worms in New Zealand shellfish

Shells of commercially valued bivalves in New Zealand, Crassostrea gigas, Perna canaliculus and Pecten novaezelandiae, are damaged by blister-causing Polydora polychaete species known to be close in morphology to the widely recorded oyster pest Polydora websteri Hartman. Recent New Zealand occurrences are here confirmed to relate to two species, P. websteri, and a second similar species, Polydora haswelli Blake & Kudenov, a new record for New Zealand, previously known only from Australia; the two species are described and compared. The worms have limited distributions, with P. websteri confirmed only for Pacific oysters (C. gigas) in northern New Zealand, although prior reports indicate it may also occur on scallops and have reached the northern South Island. Polydora haswelli has been found only in northern New Zealand, occurring on subtidal mussels and scallops and native oysters (Perna canaliculus, Pecten novaezelandiae, Ostrea chilensis), as well as co-existing with intertidal P. websteri on Pacific oysters. The worms are not present in Foveaux Strait O. chilensis beds, a major source of past oyster exports to Australia. The history of mud-blister worm outbreaks in Australasia is examined. While trans-Tasman exports of live oysters from New Zealand were commonplace during the nineteenth century, there is no evidence that mud-blister worms were present in New Zealand then. The earliest reports only date from the early 1970s and only from northern New Zealand, whereas a century earlier in the 1870s at least one of these pest worms had become widespread along eastern Australian coasts.     

Semi‐active tuned mass damper building systems: Application

Seismic performance attributes of multi‐story passive and semi‐active tuned mass damper (PTMD and SATMD) building systems are investigated for 12‐story moment resisting frames modeled as ‘10+2’ stories and ‘8+4’ stories. Segmented upper portion of the stories are isolated as a tuned mass, and a passive viscous damper or semi‐active resetable device is adopted as energy dissipation strategy. The semi‐active approach uses feedback control to alter or manipulate the reaction forces, effectively re‐tuning the system depending on the structural response. Optimum tuned mass damper control parameters and appropriate matching SATMD configurations are adopted from a companion study on a simplified two‐degree‐of‐freedom system. Statistical performance metrics are presented for 30 probabilistically scaled earthquake records from the SAC project. Time history analyses are used to compute response reduction factors across a wide range of seismic hazard intensities. Results show that large SATMD systems can effectively manage seismic response for multi‐degree‐of freedom systems across a broad range of ground motions in comparison to passive solutions. Specific results include the identification of differences in the mechanisms by which SATMD and PTMD systems remove energy, based on the differences in the devices used. Additionally, variability is seen to be tighter for the SATMD systems across the suites of ground motions used, indicating a more robust control system. While the overall efficacy of the concept is shown the major issues, such as isolation layer displacement, are discussed in detail not available in simplified spectral analyses, providing further insight into the dynamics of these issues for these systems. Copyright © 2009 John Wiley & Sons, Ltd.     

Comparison of the Hill–Siscoe polar cap potential theory with the Weimer and AMIE models

The magnetic storm on November 2004 was characterized by a high solar wind pressure and thus offers a unique opportunity to test the Hill–Siscoe formula (H–S) for the polar cap potential (PCP). To estimate the polar cap potential, we use the Weimer Statistical Convection Model (WCM), and the Assimilative Mapping of Ionospheric Electrodynamics Model (AMIE), based on ingestion of a number of data sets. H–S is in excellent agreement with WCM, and with AMIE during times when DMSP is used in the latter. The implication is that the AMIE conductivity model yields conductivities that are too high by a factor of 2–3. Both H–S and WCM display saturation effects, although WCM is more severe. The two methods track well until an IEF of about 20 mV/m occurs, where H–S continues to increase while WCM levels off. Even at high electric field values, the pressure increases the denominator of the H–S formula by 60%, keeping the potential lower than its saturation value. There are several H–S points above 250 kV, even up to 400 kV, that are not found in WCM and occur right after a rapid transition from B_z north to south. For B_z north, we find evidence for a saturation effect on the PCP at large IEF, little effect as a function of solar wind velocity, and an increase of the PCP with increasing pressure. This seems to rule out viscous interaction but may involve geometric changes in the high-altitude polar cusp that affect recombination there for B_z north.     

Mapping biodiversity

It is argued that there is no simple metadata solution to the problems of integrating information from multiple scientific disciplines in biodiversity and thus to problems of adopting GIS for producing maps of biodiversity. To the contrary, it is maintained that within this field, GIS needs to take account of and represent an irreducible ontological diversity in the many biodiversity databases being produced.     

Intensity–duration–frequency curves exploiting neighbouring extreme precipitation data

ABSTRACT

Records of precipitation extremes are essential for hydrological design. In urban hydrology, intensity–duration–frequency curves are typically estimated from observation records. However, conventional approaches seldom consider the areal extent of events. If they do, duration-dependent area reduction factors are used, but precipitation is measured at only a few locations. Due to the high spatial variability of precipitation, it is relatively unlikely that a gauged observation network will capture the extremes that occur during a precipitation event. Therefore, the area reduction approach cannot be regarded as the reduction of an observed maximum. To investigate precipitation extremes, spatial aspects need to be considered using different approaches. Here, we both address the conventional practice of area reduction and consider a within-area chance of increased precipitation, defined as the maximum precipitation intensity observed in a cluster within a selected domain. The results show that (1) the risk of urban flooding is routinely underestimated in current design practice, and (2) traditional calculations underestimate extremes by as much as 30–50%. We show how they can be revised sensibly.     

A low temperature X-ray single-crystal diffraction and polarised infra-red study of epidote

The effects of low-temperature on the crystal structure of a natural epidote [Ca_1.925Fe_0.745Al_2.265Ti_0.004Si_3.037O₁₂(OH), a = 8.8924(7), b = 5.6214(3), c = 10.1547(6)? and β = 115.396(8)° at room conditions, Sp. Gr. P2₁ /m] have been investigated with a series of structure refinements down to 100 K on the basis of X-ray single-crystal diffraction data. The reflection conditions confirm that the space group is maintained within the T-range investigated. Structural refinements at all temperatures show the presence of Fe³⁺ at the octahedral M(3) site only [%Fe(M3) = 70.6(4)% at 295 K]. Only one independent proton site was located and two possible H-bonds occur, with O(10) as donor and O(4) and O(2) as acceptors. The H-bonding scheme is maintained down to 100 K and is supported by single crystal room-T polarised FTIR data. FTIR Spectra over the region 4,000–2,500 cm⁻¹ are dominated by the presence of a strongly pleochroic absorption feature which can be assigned to protonation of O(10)–O(4). Previously unobserved splitting of this absorption features is consistent with a NNN influence due to the presence of Al and Fe³⁺ on the nearby M(3) site. An additional relatively minor absorption feature in FTIR spectra can be tentatively assigned to protonation of O(10)–O(2). Low-T does not affect significantly the tetrahedral and octahedral bond distances and angles, even when distances are corrected for “rigid body motions”. A more significant effect is observed for the bond distances of the distorted Ca(1)- and Ca(2)-polyhedra, especially when corrected for “non-correlated motion”. The main low-T effect is observed on the vibrational regime of the atomic sites, and in particular for the two Ca-sites. A significant reduction of the magnitude of the thermal displacement ellipsoids, with a variation of U _eq (defined as one-third of the trace of the orthogonalised U _ij tensor) by ~40% is observed for the Ca-sites between 295 and 100 K. Within the same T-range, the U _eq of the octahedral and oxygen sites decrease similarly by ~35%, whereas those of the tetrahedral cations by ~22%.     

Morphological similarities between DBM and a microeconomic model of sprawl

We present a model that simulates the growth of a metropolitan area on a 2D lattice. The model is dynamic and based on microeconomics. Households show preferences for nearby open spaces and neighbourhood density. They compete on the land market. They travel along a road network to access the CBD. A planner ensures the connectedness and maintenance of the road network. The spatial pattern of houses, green spaces and road network self-organises, emerging from agents individualistic decisions. We perform several simulations and vary residential preferences. Our results show morphologies and transition phases that are similar to Dieletric Breakdown Models (DBM). Such similarities were observed earlier by other authors, but we show here that it can be deducted from the functioning of the land market and thus explicitly connected to urban economic theory.     

Investigation of Small‐Scale Preferential Flow with a Forced‐Gradient Tracer Test

A new tracer experiment (referred to as MADE‐5) was conducted at the well‐known Macrodispersion Experiment (MADE) site to investigate the influence of small‐scale mass‐transfer and dispersion processes on well‐to‐well transport. The test was performed under dipole forced‐gradient flow conditions and concentrations were monitored in an extraction well and in two multilevel sampler (MLS) wells located at 6, 1.5, and 3.75 m from the source, respectively. The shape of the breakthrough curve (BTC) measured at the extraction well is strongly asymmetric showing a rapidly arriving peak and an extensive late‐time tail. The BTCs measured at seven different depths in the two MLSs are radically different from one another in terms of shape, arrival times, and magnitude of the concentration peaks. All of these characteristics indicate the presence of a complex network of preferential flow pathways controlling solute transport at the test site. Field‐experimental data were also used to evaluate two transport models: a stochastic advection‐dispersion model (ADM) based on conditional multivariate Gaussian realizations of the hydraulic conductivity field and a dual‐domain single‐rate (DDSR) mass‐transfer model based on a deterministic reconstruction of the aquifer heterogeneity. Unlike the stochastic ADM realizations, the DDSR accurately predicted the magnitude of the concentration peak and its arrival time (within a 1.5% error). For the multilevel BTCs between the injection and extraction wells, neither model reproduced the observed values, indicating that a high‐resolution characterization of the aquifer heterogeneity at the subdecimeter scale would be needed to fully capture 3D transport details.     

FT-IR measurements of cold C3H8 cross sections at 7–15 μm for Titan atmosphere

We present absorption cross sections of propane (C₃H₈) at temperatures from 145 K to 297 K in the 690–1550 cm⁻¹ region. Pure and N₂-broadened spectra were measured at pressures from 3 Torr to 742 Torr using a Bruker IFS125 FT-IR spectrometer at JPL. The gas absorption cell, developed at Connecticut College, was cooled by a closed-cycle helium refrigerator. The cross sections were measured and compiled for individual spectra recorded at various experimental conditions covering the planetary atmosphere and Titan. In addition to the cross sections, a propane pseudoline list with a frequency grid of 0.005 cm⁻¹, was fitted to the 34 laboratory spectra. Line intensities and lower state energies were retrieved for each line, assuming a constant width. Validation tests showed that the pseudoline list reproduces discrete absorption features and continuum, the latter contributed by numerous weak and hot band features, in most of the observed spectra within 3%. Based on the pseudoline list, the total intensity in the 690–1550 cm⁻¹ region was determined to be 52.93 (±3%) × 10⁻¹⁹ cm⁻¹/(molecule cm⁻²) at 296 K; this value is within 3% of the average from four earlier studies. Finally, the merit of the pseudoline approach is addressed for heavy polyatomic molecules in support of spectroscopic observation of atmospheres of Titan and other planets. The cold cross sections will be submitted to the HITRAN database (hitran.harvard.edu), and the list of C₃H₈ pseudolines will be available from a MK-IV website of JPL (http://mark4sun.jpl.nasa.gov/data/spec/Pseudo).