52 research outputs found

    Equity market contagion during global financial and Eurozone crises: Evidence from a dynamic correlation analysis

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    The devastation resulting from the recent global financial and Eurozone crises is immense. Most researchers commonly believe that the global financial crisis originated in the United States, and spread immediately to global financial hubs where it eventually became the Eurozone crisis. Several studies have been conducted on financial market contagion during both global and Eurozone crises; however, the issue of whether equity market contagion spreads from the United States to the world equity markets during these crises has not been addressed yet. Through using US dollar-denominated MSCI daily indices from fifty-five equity markets for the period 2003–2013, we have found evidence of contagion in developed and emerging markets during the global and Eurozone crises. We show that contagion spread from the United States to the world markets during both crises. Our regression results identify that the bank risk transfer between the United States and other countries is the key transmission channel for cross-country correlations. This study has an important policy implication for portfolio diversification between the United States and other countries during these crises

    Assessment of the Diversity of Fungal Community Composition Associated With Vachellia pachyceras and Its Rhizosphere Soil From Kuwait Desert

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    This research examined the general soil fungi and AM fungal communities associated with a Lonely Tree species (Vachellia pachyceras) existing in the Sabah Al-Ahmad Natural Reserve located at the Kuwait desert. The goals of the study were to describe the general fungal and AM fungal communities present in the rhizospheric, non-rhizospheric soils and roots of V. pachyceras, respectively, as well as local and non-local V. pachyceras seedlings when grown under standard nursery growing environments. Soil and root samples were analyzed for an array of characteristics including soil physicochemical composition, and culture-independent method termed PCR-cloning, intermediate variable region of rDNA, the large subunit (LSU) and internal transcribed spacer (ITS) region sequence identifications. The results reveal that the fungal phylotypes were classified in four major fungal phyla namely Ascomycota, Basidiomycota, Chytridiomycota, and Zygomycota. The largest assemblage of fungal analyses showed communities dominated by members of the phylum Ascomycota. The assays also revealed a wealth of incertae sedis fungi, mostly affiliated to uncultured fungi from diverse environmental conditions. Striking difference between rhizosphere and bulk soils communities, with more fungal diversities and Operational Taxonomic Units (OTUs) richness associated with both the field and nursery rhizosphere soils. In contrast, a less diverse fungal community was found in the bulk soil samples. The characterization of AM fungi from the root system demonstrated that the most abundant and diversified group belongs to the family Glomeraceae, with the common genus Rhizophagus (5 phylotypes) and another unclassified taxonomic group (5 phylotypes). Despite the harsh climate that prevails in the Kuwait desert, studied roots displayed the existence of considerable number of AM fungal biota. The present work thus provides a baseline of the fungal and mycorrhizal community associated with rhizosphere and non-rhizosphere soils and roots of only surviving V. pachyceras tree from the Kuwaiti desert and seedlings under nursery growing environments

    Effects of Heavy Metals and Arbuscular Mycorrhiza on the Leaf Proteome of a Selected Poplar Clone: A Time Course Analysis

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    Arbuscular mycorrhizal (AM) fungi establish a mutualistic symbiosis with the roots of most plant species. While receiving photosynthates, they improve the mineral nutrition of the plant and can also increase its tolerance towards some pollutants, like heavy metals. Although the fungal symbionts exclusively colonize the plant roots, some plant responses can be systemic. Therefore, in this work a clone of Populus alba L., previously selected for its tolerance to copper and zinc, was used to investigate the effects of the symbiosis with the AM fungus Glomus intraradices on the leaf protein expression. Poplar leaf samples were collected from plants maintained in a glasshouse on polluted (copper and zinc contaminated) or unpolluted soil, after four, six and sixteen months of growth. For each harvest, about 450 proteins were reproducibly separated on 2DE maps. At the first harvest the most relevant effect on protein modulation was exerted by the AM fungi, at the second one by the metals, and at the last one by both treatments. This work demonstrates how importantly the time of sampling affects the proteome responses in perennial plants. In addition, it underlines the ability of a proteomic approach, targeted on protein identification, to depict changes in a specific pattern of protein expression, while being still far from elucidating the biological function of each protein

    Nutritional preconditioning and ectomycorrhizal formation of Picea mariana (Mill.) B.S.P. seedlings

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    grantor: University of TorontoEctomycorrhizal inoculated seedlings may improve forest plantation establishment by enhancing growth and nutrition of newly planted seedlings, but successful nursery colonization of planting stock is often incompatible with conventional fertilization practices because of toxic inhibitive effects. A new cultural technique for seedlings is examined, called "mycorrhizal nutrient loading" that integrates exponential high dose fertilization with ectomycorrhizal association without causing serious inhibition. Containerized black spruce ('Picea mariana' (Mill.) B.S.P.) were inoculated at sowing with 'Hebeloma crustuliniforme' or 'Laccaria bicolor ' and fertilized with a complete nutrient solution conventionally at 12.5 mg N/plant and exponentially at 12.5, 25 or 50 mg N/ plant representing conventional, loading and high loading application rates, respectively. At the end of nursery culture, exponential fertilization significantly stimulated ectomycorrhizal formation at higher rates (49-85%) than those of conventionally fertilized (22-26%) seedlings. Improved ectomycorrhizal colonization, even at high loading rates, was attributed to low initial nutrient additions and lower electrical conductivity levels maintained in the growing media under exponential fertilization. The gradual increase in nutrient delivery enabled the fungi to develop tolerance to high fertilizer inputs. Nutrient loading significantly increased N (51-135%), P (29-45%), and K (13-47%) uptake of seedlings, reflecting progressive luxury consumption of nutrients. Mycorrhizal inoculation further elevated loading efficiency by stimulating plant nutrient uptake of N (9-20%), P (7-12%), and K (4-18%), demonstrating accumulation was more efficient with fungal colonization. Vector nutrient diagnosis revealed marked nutrient dilution under conventional fertilization, but induced steady-state nutrition under exponential fertilization that benefited sustained symbiosis. When outplanted on bioassays retrieved from two contrasting boreal forest (Feathermoss and Hardwood-Alnus) sites in northern Ontario, mycorrhizal nutrient loaded seedlings outperformed conventional seedlings by enhancing dry matter production (45-92%), and increasing N (80-124%), P (89-129%), and K (72-106%) assimilation. The new growth drew on greater internal nutrient reserves built up by both exponential fertilization and mycorrhizal colonization in the nursery. Results were integrated into conceptual models demonstrating interactions of fundamental processes involved in mycorrhizal nutrient loading of trees and their resource utilization after planting in relation to different nutritional regimes. Given the current concern about adequate forest regeneration in Canada, nutrient loading in combination with mycorrhizal inoculation practices provides a potentially effective tool to improve early plantation establishment on boreal sites.Ph.D

    Integer-valued moving average modelling of the number of transactions in stocks

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    The Integer-valued Moving Average Model (INMA) is advanced to model the number of transactions in intra-day data of stocks. The conditional mean and variance properties are discussed and model extensions to include explanatory variables are offered. Least squares and generalized method of moment estimators are presented. In a small Monte Carlo study a feasible least squares estimator comes out as the best choice. Empirically we find support for the use of long-lag moving average models in a Swedish stock series. There is evidence of asymmetric effects of news about prices on the number of transactions.

    Quasi-Maximum Likelihood Estimation for Long Memory Stock Transaction Data—Under Conditional Heteroskedasticity Framework

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    This paper introduces Quasi-Maximum Likelihood Estimation for Long Memory Stock Transaction Data of unknown underlying distribution. The moments with conditional heteroscedasticity have been discussed. In a Monte Carlo experiment, it was found that the QML estimator performs as well as CLS and FGLS in terms of eliminating serial correlations, but the estimator can be sensitive to start value. Hence, two-stage QML has been suggested. In empirical estimation on two stock transaction data for Ericsson and AstraZeneca, the 2SQML turns out relatively more efficient than CLS and FGLS. The empirical results suggest that both of the series have long memory properties that imply that the impact of macroeconomic news or rumors in one point of time has a persistence impact on future transactions
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