Temperature tolerances of two southern African Ecklonia species (Alariaceae: Laminariales) and of hybrids between them

The temperature tolerances in culture of Ecklonia maxima (Osbeck) Papenf., the dominant kelp in the Benguela upwelling region on the west coast of southern Africa, and the smaller E. biruncinata (Bory) Papenf., growing on the warmer south coast, have been investigated. Vegetative growth and reproduction of gametophytes show very similar patterns in the two species, although temperature optima in E. biruncinata are consistently 2 ° to 3 °C higher than those of E. maxima. Reciprocal crosses between clonal female and male gametophytes of the two species produced healthy juvenile sporophytes, indistinguishable from the parent crosses. All parents and hybrids grew well over a wide range of temperatures (8 ° to 22°C), with E. biruncinata sporophytes again having slightly higher optima than E. maxima. Both reciprocal crosses exhibited optima intermediate between the parent crosses. The results are discussed with respect to the origins and evolution of Ecklonia species in the region.     

Survey of chemical constituents of Tehran's groundwater

One hundred and forty wells throughout the City of Tehran and its environs were sampled to determine the chemical quality of the groundwater. Total alkalinity, pH, conductivity, total dissolved solids, hardness and detergent concentrations were determined as well as levels of bicarbonate, calcium, magnesium, sulphate, chloride, sodium, potassium, fluoride, iodide and nitrate. Generally, chemical pollution of the water supplies was low. There were, however, regional elevations in nitrate, chloride and fluoride. Elevated fluoride levels were primarily in the northern regions of the city while high nitrates and chlorides were found primariiy in industrial areas. The health implications of chemical constituents in drinking water are discussed.     

Does the preferential microbial colonisation of ferromagnesian minerals affect mineral weathering in soil?

Fungal activity is thought to play a direct and effective role in the breakdown and dissolution of primary minerals and in the synthesis of clay minerals in soil environments, with important consequences for plant growth and ecosystem functioning. We have studied primary mineral weathering in volcanic soils developed on trachydacite in southern Tuscany using a combination of qualitative and quantitative mineralogical and microbiological techniques. Specifically, we characterized the weathering and microbiological colonization of the magnetically separated ferromagnesian minerals (biotite and orthopyroxene) and non-ferromagnesian constituents (K-feldspar and volcanic glass) of the coarse sand fraction (250-1,000 microm). Our results show that in the basal horizons of the soils, the ferromagnesian minerals are much more intensively colonized by microorganisms than K-feldspar and glass, but that the composition of the microbial communities living on the two mineral fractions is similar. Moreover, X-ray diffraction, optical and scanning electron microscope observations show that although the ferromagnesian minerals are preferentially associated with an embryonic form of the clay mineral halloysite, they are still relatively fresh. We interpret our results as indicating that in this instance microbial activity, and particularly fungal activity, has not been an effective agent of mineral weathering, that the association with clay minerals is indirect, and that fungal weathering of primary minerals may not be as important a source of plant nutrients as previously claimed.     

Morphological responses and tolerance of a tree native to the Brazilian Cerrado Astronium fraxinifolium Schott to boron toxicity

Environmental Science and Pollution Research - The indiscriminate use of fertilizers and chemical pesticides can lead to boron contamination of the soil. Decontamination in general is expensive and...     

What is an explosion? A case history of an investigation for the insurance industry

After a large property loss, the insured and insurers of a hydroelectric power plant in North America became embroiled in subrogation to determine if the event could be characterized as an explosion. The subject insurance policy provided coverage for explosions, but excluded mechanical breakdowns. Analysis by Exponent Failure Analysis Associates indicated that a consistent, cross-disciplinary definition for explosions can be extracted from published scientific literature, and that this incident was not an explosion because certain key requirements were missing during the accident. However, this investigation has highlighted the necessity for insurance companies and their insureds to better understand this term and thereby minimize future coverage disputes. This paper presents an analysis of this incident and describes the necessary characteristics of an explosion.     

Antipredator responses of koomal (Trichosurus vulpecula hypoleucus) against introduced and native predators

Antipredator behavior studies generally assess prey responses to single predator species although most real systems contain multiple species. In multi-predator environments prey ideally use antipredator responses that are effective against all predator species, although responses may only be effective against one predator and counterproductive for another. Multi-predator systems may also include introduced predators that the prey did not co-evolve with, so the prey may either fail to recognize their threat (level 1 naiveté), use ineffective responses (level 2 naiveté) or succumb to their superior hunting ability (level 3 naiveté). We analyzed microhabitat selection of an Australian marsupial (koomal, Trichosurus vulpecula hypoleucus) when faced with spatiotemporal differences in the activity/density levels of one native (chuditch, Dasyurus geoffroii) and two introduced predators (red fox, Vulpes vulpes; feral cat, Felis catus). From this, we inferred whether koomal recognized introduced predators as a threat, and whether they minimized predation risk by either staying close to trees and/or using open or dense microhabitats. Koomal remained close to escape trees regardless of the predator species present, or activity/density levels, suggesting koomal employ this behavior as a first line of defense. Koomal shifted to dense cover only under high risk scenarios (i.e., with multiple predator species present at high densities). When predation risk was low, koomal used open microhabitats, which likely provided benefits not associated with predator avoidance. Koomal did not exhibit level 1 naiveté, although further studies are required to determine if they exhibit higher levels of naiveté (2–3) against foxes and cats.     

Turbulent secondary flows in wall turbulence: vortex forcing,scaling arguments,and similarity solution

Spanwise surface heterogeneity beneath high-Reynolds number, fully-rough wall turbulence is known to induce a mean secondary flow in the form of counter-rotating streamwise vortices—this arrangement is prevalent, for example, in open-channel flows relevant to hydraulic engineering. These counter-rotating vortices flank regions of predominant excess(deficit) in mean streamwise velocity and downwelling(upwelling) in mean vertical velocity. The secondary flows have been definitively attributed to the lower surface conditions, and are now known to be a manifestation of Prandtl’s secondary flow of the second kind—driven and sustained by spatial heterogeneity of components of the turbulent (Reynolds averaged) stress tensor (Anderson et al. J Fluid Mech 768:316–347, 2015). The spacing between adjacent surface heterogeneities serves as a control on the spatial extent of the counter-rotating cells, while their intensity is controlled by the spanwise gradient in imposed drag (where larger gradients associated with more dramatic transitions in roughness induce stronger cells). In this work, we have performed an order of magnitude analysis of the mean (Reynolds averaged) transport equation for streamwise vorticity, which has revealed the scaling dependence of streamwise circulation intensity upon characteristics of the problem. The scaling arguments are supported by a recent numerical parametric study on the effect of spacing. Then, we demonstrate that mean streamwise velocity can be predicted a priori via a similarity solution to the mean streamwise vorticity transport equation. A vortex forcing term has been used to represent the effects of spanwise topographic heterogeneity within the flow. Efficacy of the vortex forcing term was established with a series of large-eddy simulation cases wherein vortex forcing model parameters were altered to capture different values of spanwise spacing, all of which demonstrate that the model can impose the effects of spanwise topographic heterogeneity (absent the need to actually model roughness elements); these results also justify use of the vortex forcing model in the similarity solution.     

Internal cohesion and geometric shape of spatial clusters

The geographic delineation of irregularly shaped spatial clusters is an ill defined problem. Whenever the spatial scan statistic is used, some kind of penalty correction needs to be used to avoid clusters’ excessive irregularity and consequent reduction of power of detection. Geometric compactness and non-connectivity regularity functions have been recently proposed as corrections. We present a novel internal cohesion regularity function based on the graph topology to penalize the presence of weak links in candidate clusters. Weak links are defined as relatively unpopulated regions within a cluster, such that their removal disconnects it. By applying this weak link cohesion function, the most geographically meaningful clusters are sifted through the immense set of possible irregularly shaped candidate cluster solutions. A multi-objective genetic algorithm (MGA) has been proposed recently to compute the Pareto-sets of clusters solutions, employing Kulldorff’s spatial scan statistic and the geometric correction as objective functions. We propose novel MGAs to maximize the spatial scan, the cohesion function and the geometric function, or combinations of these functions. Numerical tests show that our proposed MGAs has high power to detect elongated clusters, and present good sensitivity and positive predictive value. The statistical significance of the clusters in the Pareto-set are estimated through Monte Carlo simulations. Our method distinguishes clearly those geographically inadequate clusters which are worse from both geometric and internal cohesion viewpoints. Besides, a certain degree of irregularity of shape is allowed provided that it does not impact internal cohesion. Our method has better power of detection for clusters satisfying those requirements. We propose a more robust definition of spatial cluster using these concepts.     

Correction to: Status and trends of circumpolar peregrine falcon and gyrfalcon populations

While collating contributions and comments from 36 researchers, the coordinating authors accidentally omitted Dr. Suzanne Carrière from the list of contributing co-authors. Dr. Carrière’s data are described in Tables 1 and 3, Figure 2 and several places in the narrative. The new author list is thus updated in this article.