Molecular phylogenies help resolve taxonomic confusion with Asian <Emphasis Type="Italic">Crassostrea</Emphasis> oyster species

Identification of oyster species is still largely based on phenotypic characters that are highly plastic. Prompted by the proposed introduction of the Asian oyster species Crassostrea ariakensis into the Chesapeake Bay region of the U.S.A., this study uses molecular genetic information to understand the taxonomic framework surrounding C. ariakensis and to confidently distinguish among various sympatric oyster species. Putative samples of C. ariakensis and other species of cupped oysters from across Asia were collected and phylogenetic analyses were conducted on DNA sequences of both nuclear (ITS-1) and mitochondrial (COI) regions. Trees generated based on the two independent molecular datasets were highly congruent, and indicate that many oysters collected for this study as C. ariakensis were originally misidentified. Results also indicate that C. ariakensis, C. hongkongensis and C. nippona are distinct, but closely related species. There is strong support in both analyses for a close relationship between C. gigas and C. sikamea, as well as between C. belcheri and C. gryphoides, and between C. iredalei and C. madrasensis. The parsimony analyses based on these DNA markers, however, did not provide evidence to support C. angulata as a distinct species from C. gigas. Overall, the results emphasize the need for rigorous species identification, and additional extensive and intensive sampling to more accurately determine relationships among Crassostrea species, define their geographic distributions, and establish existing sympatry patterns.     

A global evaluation of metabolic theory as an explanation for terrestrial species richness gradients

We compiled 46 broadscale data sets of species richness for a wide range of terrestrial plant, invertebrate, and ectothermic vertebrate groups in all parts of the world to test the ability of metabolic theory to account for observed diversity gradients. The theory makes two related predictions: (1) In-transformed richness is linearly associated with a linear, inverse transformation of annual temperature, and (2) the slope of the relationship is near -0.65. Of the 46 data sets, 14 had no significant relationship; of the remaining 32, nine were linear, meeting prediction 1. Model I (ordinary least squares, OLS) and model II (reduced major axis, RMA) regressions then tested the linear slopes against prediction 2. In the 23 data sets having nonlinear relationships between richness and temperature, split-line regression divided the data into linear components, and regressions were done on each component to test prediction 2 for subsets of the data. Of the 46 data sets analyzed in their entirety using OLS regression, one was consistent with metabolic theory (meeting both predictions), and one was possibly consistent. Using RMA regression, no data sets were consistent. Of 67 analyses of prediction 2 using OLS regression on all linear data sets and subsets, two were consistent with the prediction, and four were possibly consistent. Using RMA regression, one was consistent (albeit weakly), and four were possibly consistent. We also found that the relationship between richness and temperature is both taxonomically and geographically conditional, and there is no evidence for a universal response of diversity to temperature. Meta-analyses confirmed significant heterogeneity in slopes among data sets, and the combined slopes across studies were significantly lower than the range of slopes predicted by metabolic theory based on both OLS and RMA regressions. We conclude that metabolic theory, as currently formulated, is a poor predictor of observed diversity gradients in most terrestrial systems.     

Applicability of the Arrhenius model for ammonia oxidizing bacteria subjected to temperature time gradients

The aim of this work is to identify the range of applicability of Arrhenius type temperature dependence for Ammonia Oxidizing Bacteria (AOB) subjected to temperature time gradients through continuous titrimetric tests. An innovative online differential titrimetric technique was used to continuously monitor the maximum biologic ammonia oxidation rate of the biomass selected in a pilot scale membrane bioreactor, as a function of temperature time gradients. The monitoring technique is based on the measurement of alkalinity and hydrogen peroxide consumption rates in two parallel reactors operated in non-limiting substrate conditions for AOB; both reactors were continuously fed with mixed liquor and in one of them AOB were inhibited with allylthiourea. The effects of temperature decrease rates in the range 1 to 4°C·h⁻¹ were evaluated by controlling the titrimetric reactor in the temperature range 10°C–20°C. The dependence of growth kinetics on temperature time gradients and the range of applicability of Arrhenius model for temperature dependency of AOB growth kinetics were assessed. The Arrhenius model was found to be accurate only with temperature gradients lower than 2°C·h⁻¹. The estimated Arrhenius coefficients (θ) were shown to increase from 1.07 to 1.6 when the temperature decrease rate reached 4°C·h⁻¹.     

Book review

Environmental Management, (3 Volumes) Editors B. Nath, L. Hens and D. Devuyst (Brussels, Vubpress: 1993. Approx. 890 Pp. Paperback) (£25 Per Volume) Isbn 90 5487 035 4-6

The Chemistry and Deposition of Nitrogen Species in the Troposphere, Editor A. T. Cocks, Publisher Royal Society of Chemistry, 1993, X + 134pp., Isbn 0 85186 355 8, Price £35.00.     

Investigating the potential for different scooter and car exhaust emissions to cause cytotoxic and (pro-)inflammatory responses to a 3D in vitro model of the human epithelial airway

The aim of this study was to compare the cytotoxicity and the (pro-)inflammatory responses of two-stroke (direct injection and carburetor technology) and four-stroke scooter and diesel car exhaust emissions on lung cells in vitro. This was analyzed by exposing a 3D in vitro model of the epithelial airway (consisting of human bronchial epithelial cells (cell line 16HBE14o^?) combined with human whole blood monocyte-derived macrophages and dendritic cells) to physically characterized exhaust emissions. Biological endpoints of cytotoxicity (lactate dehydrogenase release), as well as pro-inflammatory cytokine (tumor necrosis factor (TNF)-α) and inflammatory chemokine (interleukin(IL)-8) stimulation were examined. Two-stroke direct injection scooter exhaust contained the highest particle number concentration and nitrogen oxides (NO _x ) concentrations and the emissions from the two-stroke carburetor scooter contained the highest hydrocarbon and lowest NO _x concentrations. The four-stroke scooter emitted the highest carbon monoxide concentration whereas the cars emitted the lowest. The combination of various technical optimizations for the two-stroke direct injection scooter (particle filter, oxidative catalyst, better oil and fuel) reduced the total emissions strongly and the TNF-α concentration significantly (p?相似文献   

Reproductive seasonality is a poor predictor of receptive synchrony and male reproductive skew among nonhuman primates

Among nonhuman primates, male reproductive skew (i.e., the distribution of reproductive success across males) appears to be affected primarily by receptive synchrony and the number of males per group. These factors have been assumed to depend on reproductive seasonality, with strong seasonality increasing receptive synchrony, which in turn reduces the strength of male monopolization associated with more males and lower skew. Here we tested the importance of reproductive seasonality for 26 populations representing 15 species living in multimale groups. We obtained data from the literature on paternity, number of males per group, receptive synchrony, and three measures of seasonality of reproduction. We analyzed these data using bivariate regressions and hierarchical regression by sets and controlled for the effect of evolutionary relationships using phylogenetic generalized least squares. As expected, alpha male paternity decreased as the number of males per group increased as well as with increasing female receptive synchrony. Reproductive seasonality did not explain variation in reproductive skew over and above the variation explained by synchrony and the number of males. Reproductive seasonality alone only explained a small proportion of the variation in skew, and there was no strong association between reproductive seasonality and synchrony. The effects of receptive synchrony and reproductive seasonality as well as their link were reduced if we excluded captive populations. These results indicate that across primates male reproductive skew is related to the number of competitors in a group and that seasonality does not reliably predict synchrony or male reproductive skew.     

Testing genuine savings as a forward-looking indicator of future well-being over the (very) long-run

Genuine Savings (GS) have been much used in recent years as an indicator of a country's sustainability. According to some theorists (e.g. Arrow et al., 2012), under certain conditions a country with a positive level of GS should experience non-declining future utility, given the assumption of unlimited substitutability among all forms of capital (sometimes called “weak” sustainability). This paper reports the first very long-run tests of GS (also called comprehensive investment or adjusted net savings) as a forward-looking indicator of future well-being. We assemble data for British capital back to 1765, and construct several net investment measures which are used as indicators of two alternative measures of future well-being: consumption per capita and real wages. An allowance for a “value of time” due to exogenous technological progress is included in some GS measures, and we demonstrate the importance of this measure and the choice of discount rate over the very long-run. On the whole, our results do not reject the postulated relationship between GS and future well-being, and show GS can be a forward looking indicator of future well-being for periods of up to 100 years.     

Is there a need for new theories,models and approaches to occupational accident prevention?

This paper discusses occupational accident modelling challenges associated with a changing working life, and asks whether ideas from models developed for high-risk, complex socio-technical systems can be transformed and adapted for use in occupational accident prevention. Are occupational accidents mainly simple component failures or is a systemic approach to the phenomenon of some interest and value?     

A study on the effect of trees on gas explosions

The downstream as well as the upstream oil and gas industry has for a number of years been aware of the potential for flame acceleration and overpressure generation due to obstacles in gas clouds caused by leaks of flammable substances. To a large extent the obstacles were mainly considered to be equipment, piping, structure etc. typically found in many installations. For landbased installations there may however also be a potential for flame acceleration in regions of vegetation, like trees and bushes. This is likely to have been the case for the Buncefield explosion that occurred in 2005 (Buncefield Major Incident Investigation Board, 2008), which led to the work described in the present paper. The study contains both a numerical and an experimental part and was performed in the period 2006–2008 (Bakke and Brewerton, 2008, Van Wingerden and Wilkins, 2008).The numerical analysis consisted of modelling the Buncefield tank farm and the surrounding area with FLACS. The site itself was not significantly congested and it was not expected to give rise to high overpressures in case of a hydrocarbon leak. However, alongside the roads surrounding the site (Buncefield Lane and Cherry Tree Lane), dense vegetation in the form of trees and bushes was included in the model. This was based on a site survey (which was documented by video) performed in the summer of 2006.A large, shallow, heavier-than-air gas cloud was defined to cover part of the site and surroundings. Upon ignition a flame was established in the gas cloud. This flame accelerated through the trees along the surrounding roads, and resulted in high overpressures of several barg being generated by FLACS. This is to the authors’ knowledge the first time a possible effect of vegetation on explosions has been demonstrated by 3D analyses.As a consequence of these results, and since the software had been validated against typical industrial congestion rather than dense vegetation, a set of experiments to try to demonstrate if these effects were physical was carried out as well. The test volume consisted of a plastic tunnel, 20 m long with a semi-circular cross-section 3.2 m in diameter allowing for representing lanes of vegetation. The total volume of the tent was approximately 80.4 m³. The experimental programme involved different degrees of vegetation size, vegetation density (blocking ratio) and number of vegetation lanes (over the full length of the tunnel). The experiments were performed with stoichiometric propane–air mixtures resulting in continuously accelerating flames over the full length of the tunnel for some of the scenarios investigated.The main conclusions of the study are that trees can have an influence on flame acceleration in gas–air clouds, and that advanced models such as FLACS can be used to study such influence. More research is needed, however, because even if FLACS predicts flame acceleration in dense vegetation, no evidence exists that applying the code to trees rather than rigid obstacles provides results of acceptable accuracy.     

焦化废水中有机污染物好氧生物降解特性的研究

在实验室条件下,采用瓦勃氏微量呼吸仪测试方法,以处理焦化废水曝气池内活性污泥作为降解所用微生物,研究了焦化废水中咪唑等6种有机污染物的好氧生物降解特性。文中的对这些有机污染物在单一基质和与苯酚共基质条件下的降解规律、它们对微生物的抑制情况进行了详细考察。在与苯酚共基质条件下,6种有机污染物的降解特性有不同程度变化。吩噻嗪、高浓度萘和咔唑抑制苯酚降解,咪唑、吡咯、蒽在共基质条件下降解性有所提高