Properties of the stochastic Gross-Pitaevskii equation: finite temperature Ehrenfest relations and the optimal plane wave representation

We present Ehrenfest relations for the high temperature stochastic Gross-Pitaevskii equation description of a trapped Bose gas, including the effect of growth noise and the energy cutoff. A condition for neglecting the cutoff terms in the Ehrenfest relations is found which is more stringent than the usual validity condition of the truncated Wigner or classical field method-that all modes are highly occupied. The condition requires a small overlap of the nonlinear interaction term with the lowest energy single particle state of the noncondensate band, and gives a means to constrain dynamical artefacts arising from the energy cutoff in numerical simulations. We apply the formalism to two simple test problems: (i) simulation of the Kohn mode oscillation for a trapped Bose gas at zero temperature, and (ii) computing the equilibrium properties of a finite temperature Bose gas within the classical field method. The examples indicate ways to control the effects of the cutoff, and that there is an optimal choice of plane wave basis for a given cutoff energy. This basis gives the best reproduction of the single particle spectrum, the condensate fraction and the position and momentum densities.

Communicative practices in online communication: A case of agreeing to disagree

Online communities have evolved beyond the realm of social phenomenon to become important knowledge-sharing media with real economic consequences. However, the sharing of knowledge and the communication of meaning through Internet technology presents many difficulties. This is particularly so for online finance forums where market-sensitive information and disinformation about exchange-traded stocks is regularly disseminated. The development of trust and the effect of misinformation in this environment are important in the growth of this communication medium. Forum administrators need to better understand and handle the development of trust. In this article, we analyze and discuss the communicative practices of a group of investors and members of an online community of interest. We found that conflict as a driver of knowledge sharing is an important consideration for forum administrators and designers.

Bilberry adulteration using the food dye amaranth

Vaccinium myrtillus or bilberry fruit is a commonly used herbal product. The usual method of determining the anthocyanin content is a single-wavelength spectrophotometric assay. Using this method, anthocyanin levels of two extracts were found to be 25% as claimed by the manufacturers. When high-performance liquid chromatography (HPLC) was used, however, one extract was found to contain 9% anthocyanins probably not derived from V. myrtillus but from an adulterant. This adulterant was subsequently identified, using HPLC, mass spectroscopy, and nuclear magnetic resonance, as amaranth, that is, 3-hydroxy-4-[(4-sulfo-1-naphthalenyl)azo]-2,7-naphthalenedisulfonic acid trisodium saltsa synthetic dark red sulfonic acid based naphthylazo dye. As described in this study, if deliberate adulteration occurs in an extract, a single-wavelength spectrophotometric assay is inadequate to accurately determine the levels of compounds such as anthocyanins. Detection of deliberate adulteration in commercial samples thus requires the use of alternative, more sophisticated, methods of analysis such as HPLC with photodiode array detection as a minimum.

Ecological-economic modeling for biodiversity management: Potential, pitfalls, and prospects

Ecologists and economists both use models to help develop strategies for biodiversity management. The practical use of disciplinary models, however, can be limited because ecological models tend not to address the socioeconomic dimension of biodiversity management, whereas economic models tend to neglect the ecological dimension. Given these shortcomings of disciplinary models, there is a necessity to combine ecological and economic knowledge into ecological-economic models. It is insufficient if scientists work separately in their own disciplines and combine their knowledge only when it comes to formulating management recommendations. Such an approach does not capture feedback loops between the ecological and the socioeconomic systems. Furthermore, each discipline poses the management problem in its own way and comes up with its own most appropriate solution. These disciplinary solutions, however are likely to be so different that a combined solution considering aspects of both disciplines cannot be found. Preconditions for a successful model-based integration of ecology and economics include (1) an in-depth knowledge of the two disciplines, (2) the adequate identification and framing of the problem to be investigated, and (3) a common understanding between economists and ecologists of modeling and scale. To further advance ecological-economic modeling the development of common benchmarks, quality controls, and refereeing standards for ecological-economic models is desirable.

Functional significance of dauciform roots: exudation of carboxylates and acid phosphatase under phosphorus deficiency in Caustis blakei (Cyperaceae)

Caustis blakei produces an intriguing morphological adaptation by inducing dauciform roots in response to phosphorus (P) deficiency. We tested the hypothesis that these hairy, swollen lateral roots play a similar role to cluster roots in the exudation of organic chelators and ectoenzymes known to aid the chemical mobilization of sparingly available soil nutrients, such as P. Dauciform-root development and exudate composition (carboxylates and acid phosphatase activity) were analysed in C. blakei plants grown in nutrient solution under P-starved conditions. The distribution of dauciform roots in the field was determined in relation to soil profile depth and matrix. The percentage of dauciform roots of the entire root mass was greatest at the lowest P concentration ([P]) in solution, and was suppressed with increasing solution [P], while in the field dauciform roots were predominately located in the upper soil horizons, and decreased with increasing soil depth. Citrate was the major carboxylate released in an exudative burst from mature dauciform roots, which also produced elevated levels of acid phosphatase activity. Malonate was the dominant internal carboxylate present, with the highest concentration in young dauciform roots. The high concentration of carboxylates and phosphatases released from dauciform roots, combined with their prolific distribution in the organic surface layer of nutrient-impoverished soils, provides an ecophysiological advantage for enhancing nutrient acquisition.

Incentive-based approaches to sustainable fisheries

The failures of traditional target-species management have led many to propose an ecosystem approach to fisheries to promote sustainability. The ecosystem approach is necessary, especially to account for fishery-ecosystem interactions, but by itself is not sufficient to address two important factors contributing to unsustainable fisheries: inappropriate incentives bearing on fishers and the ineffective governance that frequently exists in commercial, developed fisheries managed primarily by total-harvest limits and input controls. We contend that much greater emphasis must be placed on fisher motivation when managing fisheries. Using evidence from more than a dozen natural experiments in commercial fisheries, we argue that incentive-based approaches that better specify community and individual harvest or territorial rights and price ecosystem services and that are coupled with public research, monitoring, and effective oversight promote sustainable fisheries.

Protein disulfide isomerase: the structure of oxidative folding

Cellular functions hinge on the ability of proteins to adopt their correct folds, and misfolded proteins can lead to disease. Here, we focus on the proteins that catalyze disulfide bond formation, a step in the oxidative folding pathway that takes place in specialized cellular compartments. In the endoplasmic reticulum of eukaryotes, disulfide formation is catalyzed by protein disulfide isomerase (PDI); by contrast, prokaryotes produce a family of disulfide bond (Dsb) proteins, which together achieve an equivalent outcome in the bacterial periplasm. The recent crystal structure of yeast PDI has increased our understanding of the function and mechanism of PDI. Comparison of the structure of yeast PDI with those of bacterial DsbC and DsbG reveals some similarities but also striking differences that suggest directions for future research aimed at unraveling the catalytic mechanism of disulfide bond formation in the cell.

The molecular basis of temperature compensation in the Arabidopsis circadian clock

Circadian clocks maintain robust and accurate timing over a broad range of physiological temperatures, a characteristic termed temperature compensation. In Arabidopsis thaliana, ambient temperature affects the rhythmic accumulation of transcripts encoding the clock components TIMING OF CAB EXPRESSION1 (TOC1), GIGANTEA (GI), and the partially redundant genes CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY). The amplitude and peak levels increase for TOC1 and GI RNA rhythms as the temperature increases (from 17 to 27 degrees C), whereas they decrease for LHY. However, as temperatures decrease ( from 17 to 12 degrees C), CCA1 and LHY RNA rhythms increase in amplitude and peak expression level. At 27 degrees C, a dynamic balance between GI and LHY allows temperature compensation in wild-type plants, but circadian function is impaired in Ihy and gi mutant plants. However, at 12 degrees C, CCA1 has more effect on the buffering mechanism than LHY, as the cca1 and gi mutations impair circadian rhythms more than Ihy at the lower temperature. At 17 degrees C, GI is apparently dispensable for free-running circadian rhythms, although partial GI function can affect circadian period. Numerical simulations using the interlocking-loop model show that balancing LHY/CCA1 function against GI and other evening-expressed genes can largely account for temperature compensation in wild-type plants and the temperature-specific phenotypes of gi mutants.

Three-body recombination of ultracold Bose gases using the truncated Wigner method

We apply the truncated Wigner method to the process of three-body recombination in ultracold Bose gases. We find that within the validity regime of the Wigner truncation for two-body scattering, three-body recombination can be treated using a set of coupled stochastic differential equations that include diffusion terms, and can be simulated using known numerical methods. As an example we investigate the behavior of a simple homogeneous Bose gas, finding a very slight increase of the loss rate compared to that obtained by using the standard method.

Tackling the burden of injury in Australasia: developing a binational trauma registry

Existing trauma registries in Australia and New Zealand play an important role in monitoring the management of injured patients. Over the past decade, such monitoring has been translated into changes in clinical processes and practices. Monitoring and changes have been ad hoc, as there are currently no Australasian benchmarks for optimal injury management. A binational trauma registry is urgently needed to benchmark injury management to improve outcomes for injured patients.

mu O-conotoxin MrVIB selectively blocks Na(v)1.8 sensory neuron specific sodium channels and chronic pain behavior without motor deficits

The tetroclotoxin-resistant voltage-gated sodium channel (VGSC) Na(v)1.8 is expressed predominantly by damage-sensing primary afferent nerves and is important for the development and maintenance of persistent pain states. Here we demonstrate that mu O-conotoxin MrVIB from Conus marmoreus displays substantial selectivity for Na(v)1.8 and inhibits pain behavior in models of persistent pain. In rat sensory neurons, submicromolar concentrations of MrVIB blocked tetroclotoxin-resistant current characteristic of Na(v)1.8 but not Na(v)1.9 or tetroclotoxin-sensitive VGSC currents. MrVIB blocked human Nav1.8 expressed in Xenopus oocytes with selectivity at least 10-fold greater than other VGSCs. In neuropathic and chronic inflammatory pain models, allodynia and hyperalgesia were both reduced by intrathecal infusion of MrVIB (0.03-3 nmol), whereas motor side effects occurred only at 30-fold higher doses. In contrast, the nonselective VGSC blocker lignocaine displayed no selectivity for allodynia and hyperalgesia versus motor side effects. The actions of MrVIB reveal that VGSC antagonists displaying selectivity toward Na(v)1.8 can alleviate chronic pain behavior with a greater therapeutic index than nonselective antagonists.

Alveolar haemorrhage in anti-glomerular basement membrane disease without detectable antibodies by conventional assays

Anti-glomerular basement membrane (anti-GBM) disease represents the spectrum of disease attributable to circulating anti-GBM antibodies. While active anti-GBM disease in the absence of circulating anti-GBM antibodies has been described, it is considered rare with the use of current routinely available assays. We report four subjects with features consistent with active anti-GBM antibody disease without detectable antibodies by routinely available enzyme linked immunosorbent assay (ELISA) and immunoblot techniques. All were smokers who presented with diffuse alveolar haemorrhage, minimal renal involvement, and undetectable anti-GBM antibodies. Seronegative anti-GBM disease with predominant pulmonary involvement may be more common than previously appreciated and should be part of the differential diagnosis for otherwise unexplained diffuse alveolar haemorrhage. Renal biopsy with immunofluorescent studies should be considered in the diagnostic evaluation of such subjects, including those with idiopathic pulmonary haemosiderosis.

Partitioning of deformation within a subduction channel during exhumation of high-pressure rocks: a case study from the Western Alps

The metamorphic belt of the Western Alps was subjected to widespread extensional tectonism at the end of the Eocene (ca. 45-35 Ma). Extension was accommodated by hinterland-directed movements along gently inclined extensional shear zones, which facilitated rapid exhumation of high-pressure and ultra-high-pressure rocks. This deformation resulted in a normal metamorphic sequence. Extension in the inner parts of the Western Alps was coeval with shortening at the front of the belt (foreland-directed thrusts), which took place during decompression, and emplaced higher grade metamorphic units over lower grade metamorphic rocks, thus forming an inverse metamorphic sequence. Two mechanisms for this extensional episode are discussed: (1) collapse of an overthickened lithosphere, and (2) internal readjustments within the orogenic wedge due to subduction channel dynamics. We favour the latter mechanism because it can account for the development of the observed inverse and normal metamorphic sequences along foreland-directed thrusts and hinterland-directed detachments, respectively. This hypothesis is supported by published structural, metamorphic and geochronological data from four geological transects through the Western Alps. This study also emphasizes the importance of post-shearing deformation (e.g. horizontal buckling versus vertical flattening), which can modify the distribution of hinterland- and foreland-directed shear zones in orogenic belts. (c) 2006 Elsevier Ltd. All rights reserved.