351 research outputs found

    Resource Variations across the Landscape Mediate the Impact of Grazing on Vegetation in Mongolian Rangeland under High Climatic Variability

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    Assessment of grazing-induced degradation of arid and semi-arid rangelands with stochastic rainfall regimes is challenging. For the last two decades, rangeland ecologists have been discussing the relative importance of biotic and abiotic factors in controlling vegetation dynamics. According to the non-equilibrium concept, which emerged as a new paradigm to describe ecosystems in highly variable and poorly predictable environments, vegetation dynamics are driven primarily by abiotic factors such as rainfall, rather than by internal biotic regulation (e.g. grazing impact). Although a number of studies have emphasized the non-equilibrium nature of most rangelands, they have produced inconsistent results and there is still no consensus on the relative importance of grazing impact. Alternatively, recent studies have suggested that a continuum of systems exists, rather than a stark dichotomy between equilibrium and non-equilibrium rangelands. Moreover, theoretical studies have predicted that, in addition to climatic variability, resource variations occurring in space and time as a result of landscape heterogeneity should be taken into account in assessments of grazing impact. However, there have been few empirical studies of the role of resource variations in either mitigating or enhancing the impacts of grazing on vegetation. This study explores the impact of grazing strategies on vegetation in Mongolian rangelands under high climatic variability. Specifically, it is focused on key resource areas, defined in terms of the key factor determining livestock population, and thus the ability to forage during drought. Based on the prediction proposed by Illius and O’Connor (1999) that animal numbers are regulated in a density-dependent manner by the limited forage availability in key resource areas, we established and examined the hypothesis that grazing impacts would be greater in key resource areas than in other areas even in Mongolian rangelands

    Candida albicans keratitis modified by steroid application

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    The paper reports on Candida albicans ocular infection modified by steroid eye drops. A 74-year-old male complained of conjunctival injection and pain in his right eye three months after pterygium and cataract surgery. After treatment with antibiotics and steroid eye drops for three days, he was referred to our hospital. Clear localized corneal endothelial plaque with injection of ciliary body was observed. No erosion of the corneal epithelium, or infiltration of stromal edema was observed, suggesting that the pathological organism derived from the intracameral region. Because ocular infection was suspected, steroid eye drops were stopped, which led immediately to typical infectious keratitis in the pathological region, with epithelial erosion, fluffy abscess, stromal infiltration, and edema. For diagnostic purposes, the plaque was surgically removed with forceps and the anterior chamber was irrigated with antibiotics. The smear and culture examination from the plaque revealed C. albicans surrounded by neutrophils. However, aqueous fluid and fibrous tissue after gonio procedure contained no mycotic organisms. Topical fluconazole, micafungin, and pimaricin with oral itraconazole (150 mg/day) were effective. Special attention is needed when prescribing steroid eye drops to treat corneal disease especially postoperatively. Diagnosing infectious keratitis is sometimes difficult because of modification by some factors, such as postoperative conditions, scarring, and drug-induced masking. Here, we report on mycotic keratitis modified by postoperative steroid administration
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