Classifying dynamical forcing mechanisms using a climatology of extratropical cyclones

A climatology of almost 700 extratropical cyclones is compiled by applying an automated feature tracking algorithm to a database of objectively identified cyclonic features. Cyclones are classified according to the relative contributions to the midlevel vertical motion of the forcing from upper and lower levels averaged over the cyclone intensification period (average U/L ratio) and also by the horizontal separation between their upper-level trough and low-level cyclone (tilt). The frequency distribution of the average U/L ratio of the cyclones contains two significant peaks and a long tail at high U/L ratio. Although discrete categories of cyclones have not been identified, the cyclones comprising the peaks and tail have characteristics that have been shown to be consistent with the type A, B, and C cyclones of the threefold classification scheme. Using the thresholds in average U/L ratio determined from the frequency distribution, type A, B, and C cyclones account for 30\%, 38\%, and 32\% of the total number of cyclones respectively. Cyclones with small average U/L ratio are more likely to be developing cyclones (attain a relative vorticity $\ge 1.2 \times 10^{-4} \mbox{s}^{-1}$) whereas cyclones with large average U/L ratio are more likely to be nondeveloping cyclones (60\% of type A cyclones develop whereas 31\% of type C cyclones develop). Type A cyclogenesis dominates in the development region East of the Rockies and over the gulf stream, type B cyclogenesis dominates in the region off the East coast of the USA, and type C cyclogenesis is more common over the oceans in regions of weaker low-level baroclinicity.

Food-chain transfer of cadmium and zinc from contaminated Urtica dioica to Helix aspersa and Lumbricus terrestris

The present study examines the potential of Urtica dioica as an ecologically relevant species for use in ecotoxicological testing. It is prevalent in degraded ecosystems and is a food source for invertebrates. Urtica dioica grown in hydroponic solutions containing from less than 0.003 to 5.7 mg Cd/L or from 0.02 to 41.9 mg Zn/L accumulated metals resulting in leaf tissue concentrations in the range of 0.10 to 24.9 mg Cd/kg or 22.5 to 2,772.0 mg Zn/kg. No toxicological effects were apparent except at the highest concentrations tested, suggesting that this species may be an important pathway for transfer of metals to primary plant consumers. Helix aspersa and Lumbricus terrestris were fed the Cd- and Zn-rich leaves of U. dioica for six and four weeks, respectively. Cadmium and Zn body load increased with increasing metal concentration in the leaves (p < 0.001). Ratios of invertebrate metal concentration to leaf metal concentration were in the range of 1:0.03 to 1:1.4 for Cd and 1:0.2 to 1:2.8 for Zn in H. aspersa and 1:0.002 to 1:3.9 for Cd and 1:0.2 to 1:8.8 for Zn in L. terrestris. Helix aspersa Cd and Zn tissue concentrations (15.5 and 1,220.2 mg/kg, respectively) were approximately threefold those in L. terrestris when both species were fed nettle leaves with concentrations of approximately 23 mg Cd/ kg and 3,400 mg Zn/kg. Models demonstrate that L. terrestris Cd tissue concentrations (r(2) = 0.74, p < 0.001) and H. aspersa Zn tissue concentrations (r(2) = 0.69, p < 0.001) can be estimated from concentrations of Cd and Zn within the leaves of U. dioica and suggest that reasonably reproducible results can be obtained using these species for ecotoxicological testing.

Characterization of the quaternary amine transporters of Rhizobium leguminosarum bv. viciae 3841

Rhizobium leguminosarum bv. viciae 3841 contains six putative quaternary ammonium transporters (Qat), of the ABC family. Qat6 was strongly induced by hyperosmosis although the solute transported was not identified. All six systems were induced by the quaternary amines choline and glycine betaine. It was confirmed by microarray analysis of the genome that pRL100079-83 (qat6) is the most strongly upregulated transport system under osmotic stress, although other transporters and 104 genes are more than threefold upregulated. A range of quaternary ammonium compounds were tested but all failed to improve growth of strain 3841 under hyperosmotic stress. One Qat system (gbcXWV) was induced 20-fold by glycine betaine and choline and a Tn5::gbcW mutant was severely impaired for both transport and growth on these compounds, demonstrating that it is the principal system for their use as carbon and nitrogen sources. It transports glycine betaine and choline with a high affinity (apparent K-m, 168 and 294 nM, respectively).

The influence of larval density, food availability and habitat longevity on the life history and population growth rate of the midge Chironomus riparius

Despite long-standing interest in the forms and mechanisms of density dependence, these are still imperfectly understood. However, in a constant environment an increase in density must reduce per capita resource availability, which in turn leads to reduced survival, fecundity and somatic growth rate. Here we report two population experiments examining the density dependent responses under controlled conditions of an important indicator species, Chironomus riparius. The first experiment was run for 35 weeks and was started at low density with replicate populations being fed three different rations. Increased ration reduced generation time and increased population growth rate (pgr) but had no effect on survival, fecundity and female body weight in the first generation. In the second generation there was a six-fold increase in generation time, presumably due to the greatly reduced per capita resource availability as the estimated initial densities of the second generation were 300 times greater than the first. Juvenile survival to emergence, fecundity, adult body weight and pgr declined by 90%, 75%, 35% and 99%, respectively. These large between-generation effects may have obscured the effects of the threefold variation in ration, as only survival to emergence significantly increased with ration in the second generation. These results suggest that some chironomid larvae survive a reduction in resource availability by growing more slowly. In the ephemeral habitats sometimes occupied by C. riparius, the effects of population density may depend crucially on the longevity of the environment. A second experiment was therefore performed to measure pgr from six different starting densities over an eight-week period. The relationship between pgr and density was concave, viewed from above. At densities above 16 larvae per cm(2), less than 1% of the population emerged and no offspring were produced. Under the conditions of experiment 2 - an 8-week habitat lifespan carrying capacity was estimated as 8 larvae per cm(2).

Enantiospecific assembly of a homochiral, hexanuclear palladium complex

The linking of orthopalladated ferrocenylene units by parabanato(2-) ligands results in enantiospecific assembly of a hexanuclear complex in which (i) the steric bulk of the ferrocenylene moiety, (ii) the folded configuration dictated by the imidato(2-) bridging ligand, and (iii) the strong preference for a trans arrangement of the carbonyl oxygen and ferrocenyl carbon atoms, combine to ensure that only ferrocenylene-palladium units with the same chirality can be located at adjacent positions in the assembled complex. The resulting tris-parabanato(2-)-bridged, hexapalladium complex is thus homochiral (R,R,R,R,R,R or S,S,S,S,S,S), as demonstrated by H-1 NMR spectroscopy and by X-ray analysis of a racemic crystal which shows the complex to possess a tapering, twisted, trigonal-prismatic skeleton of palladium atoms with threefold crystallographic symmetry. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Effects of high pressure/thermal treatment on lipid oxidation in beef and chicken muscle

Lipid oxidation was studied in beef and chicken muscle after high pressure treatment (0.1-800 MPa) at different temperatures (20-70 degrees C for 20 min, prior to storage at 4 degrees C for 7 days. Pressure treatment of beef samples at room temperature led to increases in TBARS values after 7 days storage at 4 degrees C; however, the increases were more marked after treatment at pressures >= 400 MPa (at least fivefold) than after treatment at lower pressures (less than threefold). Similar results were found in those samples treated at 40 degrees C, but at 60 degrees C and 70 degrees C pressure had little additional effect on the oxidative stability of the muscle. Pressure treatments of 600 MPa and 800 MPa, at all temperatures. induced increased rates of lipid oxidation in chicken muscle, but, in general, chicken muscle was more stable than beef to pressure. and the catalytic effect of pressure was still seen at the higher temperatures of 50 degrees C, 60 degrees C and 70 degrees C. The addition of 1%, Na(2)EDTA decreased TBARS values of the beef muscle during storage and inhibited the increased rates of lipid oxidation induced by pressure. The inhibition by vitamin E (0.05% w/w) and BHT (0.02% w/w), either alone or in combination, were less marked than seen with Na(2)EDTA, suggesting that transition metal ions released from insoluble complexes are of major importance in catalysing lipid oxidation in pressure-treated muscle foods. (c) 2007 Elsevier Ltd. All rights reserved.

Best practice in the training, appointment and remuneration of members of dispute boards for large infrastructure projects

This paper reports part of a qualitative study into evolving practice in the implementation of the Dispute Adjudication Board (DAB) construction dispute resolution technique, a variant of the Dispute Review Board (DRB) concept used in the US and Canada. Data was collected through a focus group interview of 20 highly experienced dispute resolution practitioners from engineering and the law. The group was assembled from members of FIDIC-NET with direct experience of project DABs. The part reported here concerns practice and procedure for establishing DABs. The main findings are that: constitution of the DABs is often delayed because of either project owners' ignorance of the DAB process or deterrence by the cost of the DABs; such owners also tend to insist on appointing DAB members from local engineers and lawyers without sufficient understanding of the DAB process; rates of remuneration of DAB members vary widely; the training provision for DAB membership and advocacy skills is inadequate; the process of selecting candidates for DAB membership and negotiating the tripartite agreement between each member and the contractual parties needs to be navigated with great care to avoid raising ethical problems. The research contribution is threefold. First, it highlights the importance of realistic fees for DAB members within a standard framework in achieving timely establishment of a board that works well as a team. Second, it illustrates the use of qualitative focus group interview to study the impact of new contract terms from multiple stakeholder perspectives. Finally, it identifies areas where further research is needed.

Weak intermolecular interactions in an ionically bound molecular adsorbate: cyclopentadienyl=Cu(111)

The dissociative adsorption of cyclopentadiene (C5H6) on Cu(111) yields a cyclopentadienyl (Cp) species with strongly anionic characteristics. The Cp potential energy surface and frictional coupling to the substrate are determined from measurements of dynamics of the molecule together with density functional calculations. The molecule is shown to occupy degenerate threefold adsorption sites and molecular motion is characterized by a low diffusional energy barrier of 40 +/- 3 meV with strong frictional dissipation. Repulsive dipole-dipole interactions are not detected despite charge transfer from substrate to adsorbate.

Commensalism in an agroecosystem: hydraulic redistribution by deep-rooted legumes improves survival of a droughted shallow-rooted legume companion

We investigated commensalism of water use among annual shallow-rooted and perennial deep-rooted pasture legumes by examining the effect of hydraulic lift by Cullen pallidum (N.T.Burb.) J.W.Grimes and Medicago sativa on growth, survival and nutrient uptake of Trifolium subterraneum L. A vertically split-root design allowed separate control of soil water in top and bottom soil. Thirty-five days after watering ceased in the top tube, but soil remained at field capacity in the bottom tube, an increase in shallow soil water content by hydraulic lift was 5.6 and 5.9 g kg−1 soil overnight for C. pallidum and M. sativa, respectively. Trifolium subterraneum in this treatment maintained higher leaf water potentials (with M. sativa) or exhibited a slower decline (with C. pallidum) than without companion perennial plants; and shoot biomass of T. subterraneum was 56% (with C. pallidum) and 67% (with M. sativa) of that when both top and bottom tubes were at field capacity. Uptake of rubidium (a potassium analog) and phosphorus by T. subterraneum was not facilitated by hydraulic lift. Interestingly, phosphorus content was threefold greater, and shoot biomass 1.5–3.3-fold greater when T. subterraneum was interplanted with C. pallidum compared with M. sativa, although dry weight of C. pallidum was much greater than that of M. sativa. This study showed that interplanting with deep-rooted perennial legumes has benefited the survival of T. subterraneum.