2,643 research outputs found

    A summary of the published data on host plants and morphology of immature stages of Australian jewel beetles (Coleoptera: Buprestidae) : with additional new records

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    A summary is given of the published host plant and descriptive immature stage morphology data for 671 species and 11 subspecies in 54 genera of Australian jewel beetles (Coleoptera: Buprestidae). New host data for 155 species and 3 subspecies in 17 genera including the first published data for 75 species are included

    A comparison of the use of X-ray and neutron tomographic core scanning techniques for drilling projects: insights from scanning core recovered during the Alpine Fault Deep Fault Drilling Project

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    Abstract. It is now commonplace for non-destructive X-ray computed tomography (CT) scans to be taken of core recovered during a drilling project. However, other forms of tomographic scanning are available, and these may be particularly useful for core that does not possess significant contrasts in density and/or atomic number to which X-rays are sensitive. Here, we compare CT and neutron tomography (NT) scans of 85 mm diameter core recovered during the first phase of the Deep Fault Drilling Project (DFDP-1) through New Zealand's Alpine Fault. For the instruments used in this study, the highest resolution images were collected in the NT scans. This allows clearer imaging of some rock features than in the CT scans. However, we observe that the highly neutron beam attenuating properties of DFDP-1 core diminish the quality of images towards the interior of the core. A comparison is also made of the suitability of these two scanning techniques for a drilling project. We conclude that CT scanning is far more favourable in most circumstances. Nevertheless, it could still be beneficial to take NT scans over limited intervals of suitable core, where varying contrast is desired. </jats:p

    Use of TanDEM-X and Sentinel Products to Derive Gully Activity Maps in Kunene Region (Namibia) Based on Automatic Iterative Random Forest Approach

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    Gullies are landforms with specific patterns of shape, topography, hydrology, vegetation, and soil characteristics. Remote sensing products (TanDEM-X, Sentinel-1, and Sentinel-2) serve as inputs into an iterative algorithm, initialized using a micromapping simulation as training data, to map gullies in the northwestern of Namibia. A Random Forest Classifier examines pixels with similar characteristics in a pool of unlabeled data, and gully objects are detected where high densities of gully pixels are enclosed by an alpha shape. Gully objects are used in subsequent iterations following a mechanism where the algorithm uses the most reliable pixels as gully training samples. The gully class continuously grows until an optimal scenario in terms of accuracy is achieved. Results are benchmarked with manually tagged gullies (initial gully labeled area <0.3% of the total study area) in two different watersheds (408 and 302 km2, respectively) yielding total accuracies of >98%, with 60% in the gully class, Cohen Kappa >0.5, Matthews Correlation Coefficient >0.5, and receiver operating characteristic Area Under the Curve >0.89. Hence, our method outlines gullies keeping low false-positive rates while the classification quality has a good balance for the two classes (gully/no gully). Results show the most significant gully descriptors as the high temporal radar signal coherence (22.4%) and the low temporal variability in Normalized Difference Vegetation Index (21.8%). This research builds on previous studies to face the challenge of identifying and outlining gully-affected areas with a shortage of training data using global datasets, which are then transferable to other large (semi-) arid regions.This research is part of the DEM_HYDR2024 project sup ported by TanDEM-X Science Team, therefore the authors would like to express thanks to the Deutsches Zentrum für Luft und Raumfahrt (DLR) as the donor for the used TanDEM-X datasets. They acknowledge the financial support provided by the Namibia University of Science and Technology (NUST) within the IRPC research funding programme and to ILMI for the sponsorship of field trips to identify suitable study areas. Finally, they would like to express gratitude toward Heidelberg University and the Kurt-Hiehle-Foundation for facilitating the suitable work conditions during this research

    Soil Microbes Compete Strongly with Plants for Soil Inorganic and Amino Acid Nitrogen in a Semiarid Grassland Exposed to Elevated CO\u3ci\u3e2\u3c/i\u3e and Warming

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    Free amino acids (FAAs) in soil are an important N source for plants, and abundances are predicted to shift under altered atmospheric conditions such as elevated CO2. Composition, plant uptake capacity, and plant and microbial use of FAAs relative to inorganic N forms were investigated in a temperate semiarid grassland exposed to experimental warming and free-air CO2 enrichment. FAA uptake by two dominant grassland plants, Bouteloua gracilis and Artemesia frigida, was determined in hydroponic culture. B. gracilis and microbial N preferences were then investigated in experimental field plots using isotopically labeled FAA and inorganic N sources. Alanine and phenylalanine concentrations were the highest in the field, and B. gracilis and A. frigida rapidly consumed these FAAs in hydroponic experiments. However, B. gracilis assimilated little isotopically labeled alanine, ammonium and nitrate in the field. Rather, soil microbes immobilized the majority of all three N forms. Elevated CO2 and warming did not affect plant or microbial uptake. FAAs are not direct sources of N for B. gracilis, and soil microbes outcompete this grass for organic and inorganic N when N is at peak demand within temperate semiarid grasslands

    Long-term exposure to elevated CO\u3csub\u3e2\u3c/sub\u3e enhances plant community stability by suppressing dominant plant species in a mixed-grass prairie

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    Climate controls vegetation distribution across the globe, and some vegetation types are more vulnerable to climate change, whereas others are more resistant. Because resistance and resilience can influence ecosystem stability and determine how communities and ecosystems respond to climate change, we need to evaluate the potential for resistance as we predict future ecosystem function. In a mixed-grass prairie in the northern Great Plains, we used a large field experiment to test the effects of elevated CO2, warming, and summer irrigation on plant community structure and productivity, linking changes in both to stability in plant community composition and biomass production. We show that the independent effects of CO2 and warming on community composition and productivity depend on interannual variation in precipitation and that the effects of elevated CO2 are not limited to water saving because they differ from those of irrigation. We also show that production in this mixed-grass prairie ecosystem is not only relatively resistant to interannual variation in precipitation, but also rendered more stable under elevated CO2 conditions. This increase in production stability is the result of altered community dominance patterns: Community evenness increases as dominant species decrease in biomass under elevated CO2. In many grasslands that serve as rangelands, the economic value of the ecosystem is largely dependent on plant community composition and the relative abundance of key forage species. Thus, our results have implications for how we manage native grasslands in the face of changing climate

    Anisotropic magnetoresistance in the organic superconductor β″–(BEDT-TTF)2SF5CH2CF2SO3

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    In this paper, we report transport measurements of interlayer magnetoresistance with field parallel and perpendicular to the current direction in an all organic superconductor β″–(BEDT-TTF)₂SF₅CH₂CF₂SO₃. For H∥I, the isothermal magnetoresistance R(H) at low temperatures (

    Antecedent moisture and temperature conditions modulate the response of ecosystem respiration to elevated CO\u3csub\u3e2\u3c/sub\u3e and warming

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    Terrestrial plant and soil respiration, or ecosystem respiration (Reco), represents a major CO2 flux in the global carbon cycle. However, there is disagreement in how Reco will respond to future global changes, such as elevated atmosphere CO2 and warming. To address this, we synthesized six years (2007–2012) of Reco data from the Prairie Heating And CO2 Enrichment (PHACE) experiment. We applied a semi-mechanistic temperature–response model to simultaneously evaluate the response of Reco to three treatment factors (elevated CO2, warming, and soil water manipulation) and their interactions with antecedent soil conditions [e.g., past soil water content (SWC) and temperature (SoilT)] and aboveground factors (e.g., vapor pressure deficit, photosynthetically active radiation, vegetation greenness). The model fits the observed Reco well (R2 = 0.77). We applied the model to estimate annual (March–October) Reco, which was stimulated under elevated CO2 in most years, likely due to the indirect effect of elevated CO2 on SWC. When aggregated from 2007 to 2012, total six-year Reco was stimulated by elevated CO2 singly (24%) or in combination with warming (28%). Warming had little effect on annual Reco under ambient CO2, but stimulated it under elevated CO2 (32% across all years) when precipitation was high (e.g., 44% in 2009, a ‘wet’ year). Treatment-level differences in Reco can be partly attributed to the effects of antecedent SoilT and vegetation greenness on the apparent temperature sensitivity of Reco and to the effects of antecedent and current SWC and vegetation activity (greenness modulated by VPD) on Reco base rates. Thus, this study indicates that the incorporation of both antecedent environmental conditions and aboveground vegetation activity are critical to predicting Reco at multiple timescales (subdaily to annual) and under a future climate of elevated CO2 and warming

    Asymptotics for turbulent flame speeds of the viscous G-equation enhanced by cellular and shear flows

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    G-equations are well-known front propagation models in turbulent combustion and describe the front motion law in the form of local normal velocity equal to a constant (laminar speed) plus the normal projection of fluid velocity. In level set formulation, G-equations are Hamilton-Jacobi equations with convex (L1L^1 type) but non-coercive Hamiltonians. Viscous G-equations arise from either numerical approximations or regularizations by small diffusion. The nonlinear eigenvalue Hˉ\bar H from the cell problem of the viscous G-equation can be viewed as an approximation of the inviscid turbulent flame speed sTs_T. An important problem in turbulent combustion theory is to study properties of sTs_T, in particular how sTs_T depends on the flow amplitude AA. In this paper, we will study the behavior of Hˉ=Hˉ(A,d)\bar H=\bar H(A,d) as A+A\to +\infty at any fixed diffusion constant d>0d > 0. For the cellular flow, we show that Hˉ(A,d)O(logA)for all d>0. \bar H(A,d)\leq O(\sqrt {\mathrm {log}A}) \quad \text{for all $d>0$}. Compared with the inviscid G-equation (d=0d=0), the diffusion dramatically slows down the front propagation. For the shear flow, the limit \nit limA+Hˉ(A,d)A=λ(d)>0\lim_{A\to +\infty}{\bar H(A,d)\over A} = \lambda (d) >0 where λ(d)\lambda (d) is strictly decreasing in dd, and has zero derivative at d=0d=0. The linear growth law is also valid for sTs_T of the curvature dependent G-equation in shear flows.Comment: 27 pages. We improve the upper bound from no power growth to square root of log growt
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