3,345 research outputs found

    The effects of domestic climate change measures on international competitiveness

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    Under the Kyoto Protocol, industrialized countries (called Annex I countries) have to reduce their combined emissions to 5 percent below 1990 levels in the first commitment period of 2008-12. Efforts to reduce emissions to meet Kyoto targets and beyond have raised issues of competitiveness in countries that are implementing these policies,as well as fear of leakage of carbon-intensive industries to non-implementing countries. This has also led to proposals for tariff or border tax adjustments to offset any adverse impact of capping carbon dioxide emissions. This paper examines the implications of climate change policies such as carbon tax and energy efficiency standards on competitiveness across industries, as well as issues related to leakage, if any, of carbon-intensive industries to developing countries. Although competitiveness issues have been much debated in the context of carbon taxation policies, the study finds no evidence that the energy intensive industries’ competitiveness is affected by carbon taxes. In fact, the analysis suggests that exports of most energy-intensive industries increase when a carbon tax is imposed by the exporting countries, or by both importing and exporting countries. This finding gives credence to the initial assumption that recycling the taxes back to the energy-intensive industries by means of subsidies and exemptions may be overcompensating for the disadvantage to those industries. There is, however, no conclusive evidence that supports relocation (leakage) of carbon-intensive industries to developing countries due to stringent climate change policies.Climate Change Mitigation and Green House Gases,Climate Change Economics,Energy and Environment,Environment and Energy Efficiency,Transport Economics Policy&Planning

    Highly efficient MRI through multi-shot echo planar imaging

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    Multi-shot echo planar imaging (msEPI) is a promising approach to achieve high in-plane resolution with high sampling efficiency and low T2* blurring. However, due to the geometric distortion, shot-to-shot phase variations and potential subject motion, msEPI continues to be a challenge in MRI. In this work, we introduce acquisition and reconstruction strategies for robust, high-quality msEPI without phase navigators. We propose Blip Up-Down Acquisition (BUDA) using interleaved blip-up and -down phase encoding, and incorporate B0 forward-modeling into Hankel structured low-rank model to enable distortion- and navigator-free msEPI. We improve the acquisition efficiency and reconstruction quality by incorporating simultaneous multi-slice acquisition and virtual-coil reconstruction into the BUDA technique. We further combine BUDA with the novel RF-encoded gSlider acquisition, dubbed BUDA-gSlider, to achieve rapid high isotropic-resolution MRI. Deploying BUDA-gSlider with model-based reconstruction allows for distortion-free whole-brain 1mm isotropic T2 mapping in about 1 minute. It also provides whole-brain 1mm isotropic diffusion imaging with high geometric fidelity and SNR efficiency. We finally incorporate sinusoidal wave gradients during the EPI readout to better use coil sensitivity encoding with controlled aliasing.Comment: 13 pages, 10 figure

    Seed-borne mycoflora of local and improved wheat (Triticum sativum L.) cultivars in Kano, Nigeria

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    Three varieties each of local and improved wheat (Triticum sativum) cultivars were investigated for seed-borne pathogenic mycoflora using the plate technique and laid on completely randomized design. A total 99 fungal isolate grouped into five fungal species namely; Rhizopus nigricans, Mucor spp, Penillium jenseni, Aspergillus niger, and Fusarium moloniformes were isolated with Rhizopus nigricans, and Fusarium moloniformes (30.30 % and 35.40%, respectively) being the most frequently occurring fungal species and Penillium jenseni (7.0 %) being the least abundant. Results of the studyhave also indicated that local wheat cultivars were more contaminated than the improved varieties. It is therefore apparent that both improved and local wheat varieties are contaminated by fungal mycoflora.Keywords; wheat, seed-borne fungi, plate techniqu

    Effects of direct-fed lactic acid bacteria on weight gain and ruminal pH of two south African sheep breeds

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    A ruminant’s digestion depends on microbial degradation of feed rather than endogenous enzyme degradation as in most monogastric animals. The study was conducted to assess the effects of Lactic Acid Bacteria (LAB) strains administered as direct-fed microbials on weight gain and ruminal pH of Damara and Meatmaster sheep breeds. Sixty-four Damara and Meatmaster sheep breeds [Damara males (36.6 } 8.3 kg); Damara females (28.9 } 6.9 kg); Meatmaster males (24.6 } 3.4 kg); Meat master females (21.5 } 3.1 kg)] were subjected to a 30-day trial and divided into five treatment groups as follows: pellets with no antibiotic and no probiotics administered (T1); pellets with no antibiotics, only Lactobacillus rhamnosus SCH administered (T2); pellets with no antibiotics, only Lactobacillus rhamnosus AF3G administered (T3); pellets with no antibiotics, with the combination of Lactobacillus rhamnosus SCH and Lactobacillus rhamnosus AF3G, administered (T4); pellets fortified with antibiotic and no probiotic administered (T5). The animals were fed on commercial pellets fortified with or without antibiotics. Animals were each weighed, and rumen fluids were collected using a stomach tube, and pH was read immediately, before and at the end of the trials. Data obtained were subjected to analysis of variance using SPSS version 4.0. The results showed that the effect of treatment, sex and some of their interactive effects were significant (p <0.001) on the body weight of sheep irrespective of breed. The effect of treatments revealed that the animals in the combination of probiotics gained more weight than those in other groups. Damara breed had a heavier body weight than Meatmaster while males were 6 kg heavier relative to females (p <0.001). Only breed was significant (p <0.05) on weight gained. Treatment (p <0.05), breed (p <0.001) and their interactive effect (p <0.05) were significant on ruminal pH. The highest pH value was 7.27 for the T5 group and 7.37 for the Damara breed. Results suggest that LAB may have beneficial effects on the growth performances of sheep and therefore may be suitable as future growth promoters in sheep production, as they don't have any harmful residues compared to antibiotics

    Potential of plant beneficial bacteria and arbuscular mycorrhizal fungi in phytoremediation of metal-contaminated saline soils

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    Phytoremediation has been considered as a promising technique to decontaminate polluted soils. However, climatic stress particularly salinity, is a potential threat to soil properties and plant growth, thus restricting the employment of this technology. The aim of this study was to access the impact of microbial inoculation on phytoremediation of nickel (Ni) contaminated saline soils using Helianthus annuus. Salt resistant plant beneficial bacterium (PBB) Pseudomonas libanensis TR1 and arbuscular mycorrhizal fungus (AMF) Claroideoglomus claroideum BEG210 were used. Inoculation of P. libanensis alone or in combination with C. claroideum significantly enhanced plant growth, changed physiological status (e.g. electrolyte leakage, chlorophyll, proline and malondialdehyde contents) as well as Ni and sodium (Na+) accumulation potential (e.g. uptake and translocation factor of Ni and Na+) of H. annuus under Ni and salinity stress either alone or in combination. These results revealed that bioaugmentation of microbial strains may serve as a preferred strategy for improving phytoremediation of metal-polluted saline soils.info:eu-repo/semantics/publishedVersio

    Serpentine bacteria influence metal translocation and bioconcentration of Brassica juncea and Ricinus communis grown in multi-metal polluted soils

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    The aim of this study was to assess the effects of inoculation of rhizosphere or endophytic bacteria (Psychrobacter sp. SRS8 and Pseudomonas sp. A3R3, respectively) isolated from a serpentine environment on the plant growth and the translocation and accumulation of Ni, Zn, and Fe by Brassica juncea and Ricinus communis on a multi-metal polluted serpentine soil (SS). Field collected SS was diluted to 0, 25, 50, and 75% with pristine soil in order to obtain a range of heavy metal concentrations and used in microcosm experiments. Regardless of inoculation with bacteria, the biomass of both plant species decreased with increase of the proportion of SS. Inoculation of plants with bacteria significantly increased the plant biomass and the heavy metal accumulation compared with non-inoculated control in the presence of different proportion of SS, which was attributed to the production of plant growth promoting and/or metal mobilizing metabolites by bacteria. However, SRS8 showed a maximum increase in the biomass of the test plants grown even in the treatment of 75% SS. In turn, A3R3 showed maximum effects on the accumulation of heavy metals in both plants. Regardless of inoculation of bacteria and proportion of SS, both plant species exhibited low values of bioconcentration factor (<1) for Ni and Fe. The inoculation of both bacterial strains significantly increased the translocation factor (TF) of Ni while decreasing the TF of Zn in both plant species. Besides this contrasting effect, the TFs of all metals were <1, indicating that all studied bacteria–plant combinations are suitable for phytostabilization. This study demonstrates that the bacterial isolates A3R3 and SRS8 improved the growth of B. juncea and R. communis in SS soils and have a great potential to be used as inoculants in phytostabilization scenarios of multi-metal contaminated soils.info:eu-repo/semantics/publishedVersio

    The hyperaccumulator Sedum plumbizincicola harbors metal-resistant endophytic bacteria that improve its phytoextraction capacity in multi-metal contaminated soil

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    Endophyte-assisted phytoremediation has recently been suggested as a successful approach for ecological restoration of metal contaminated soils, however little information is available on the influence of endophytic bacteria on the phytoextraction capacity of metal hyperaccumulating plants in multimetal polluted soils. The aims of our study were to isolate and characterize metal-resistant and 1-aminocyclopropane-1-carboxylate (ACC) utilizing endophytic bacteria from tissues of the newly discovered Zn/Cd hyperaccumulator Sedum plumbizinci cola and to examine if these endophytic bacterial strains could improve the efficiency of phytoextraction of multi-metal contaminated soils. Among a collection of 42 metal resistant bacterial strains isolated from the tissues of S. plumbizinci cola grown on Pb/Zn mine tailings, five plant growth promoting endophytic bacterial strains (PGPE) were selected due to their ability to promote plant growth and to utilize ACC as the sole nitrogen source. The five isolates were identified as Bacillus pumilus E2S2, Bacillus sp. E1S2, Bacillus sp. E4S1, Achromobacter sp. E4L5 and Stenotrophomonas sp. E1L and subsequent testing revealed that they all exhibited traits associated with plant growth promotion, such as production of indole-3-acetic acid and siderophores and solubilization of phosphorus. These five strains showed high resistance to heavy metals (Cd, Zn and Pb) and various antibiotics. Further, inoculation of these ACC utilizing strains significantly increased the concentrations of water ektractable Cd and Zn in soil. Moreover, a pot experiment was conducted to elucidate the effects of inoculating metal-resistant ACC utilizing strains on the growth of S. plumbizincicola and its uptake of Cd, Zn and Pb in multi-metal contaminated soils. Out of the five strains, B. pumilus E2S2 significantly increased root (146%) and shoot (17%) length, fresh (37%) and dry biomass (32%) of S. plumbizincicola as well as plant Cd uptake (43%), whereas Bacillus sp. E1S2 significantly enhanced the accumulation of Zn (18%) in plants compared with non-inoculated controls. The inoculated strains also showed high levels of colonization in rhizosphere and plant tissues. Results demonstrate the potential to improve phytoextraction of soils contaminated with multiple heavy metals by inoculating metal hyperaccumulating plants with their own selected functional endophytic bacterial strains.info:eu-repo/semantics/acceptedVersio

    Unexpected features of branched flow through high-mobility two-dimensional electron gases

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    GaAs-based two-dimensional electron gases (2DEGs) show a wealth of remarkable electronic states, and serve as the basis for fast transistors, research on electrons in nanostructures, and prototypes of quantum-computing schemes. All these uses depend on the extremely low levels of disorder in GaAs 2DEGs, with low-temperature mean free paths ranging from microns to hundreds of microns. Here we study how disorder affects the spatial structure of electron transport by imaging electron flow in three different GaAs/AlGaAs 2DEGs, whose mobilities range over an order of magnitude. As expected, electrons flow along narrow branches that we find remain straight over a distance roughly proportional to the mean free path. We also observe two unanticipated phenomena in high-mobility samples. In our highest-mobility sample we observe an almost complete absence of sharp impurity or defect scattering, indicated by the complete suppression of quantum coherent interference fringes. Also, branched flow through the chaotic potential of a high-mobility sample remains stable to significant changes to the initial conditions of injected electrons.Comment: 22 pages, 4 figures, 1 tabl
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