77 research outputs found

    Drought effects on buds growth and dynamic of Tunisian cork oak populations

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    Forest species have adapted to their local climate by changing some of their phenological characteristics. Differential phenological responses may modify tree chance of survival by altering the competitive balance between them. The study of key phenological stages (budding, budburst, flowering, falling leaves ...) knew a renewed interest these last years for climate changes consequences researches. Characterizing the phenological variability response, of five Tunisian cork oak populations from contrasting climatic situations, in front to water deficit, has been the subject of this study. Large differences between populations from highest and coldest sites as well as those of lowest and warm sites were detected and adaptative responses specific to some populations were founded

    Review of Multilevel Inverter Topologies and Its Applications

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    Nowadays, multilevel inverter technologies have attracted attention as a convenient solution in many industrial applications. There are a few interesting features of using this configuration, where less component count, less switching losses, and improved output voltage/current waveform. The most significant criteria in multilevel inverter is the minimization of harmonic components in the inverter output voltage/current. The evolution of multilevel inverter technologies and the commercial products based on a multilevel inverter topology has shown tremendous developments due to the many advantages. In this paper, a review of the classical multilevel inverters and the recently introduced topologies are presented. They are trending as the most preferable power electronics device that have been widely used in the applications like motor-drive applications up to MegaWatt (MW) power levels, renewable energy (solar/wind power inverters) and reactive power compensation (i.e. STATCOM). This paper provides a general comparisons for various type of multilevel inverters and their suitable applications with useful references

    Emergency medicine in Oman: current status and future challenges

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    The Sultanate of Oman has a relatively young national health care system that could demonstrate its high performance at an international level. Emergency medicine as a specialty has developed rapidly in the country over the last decade. This has involved the parallel development of local emergency residency training, prehospital emergency care, and emergency nursing programs. This article reviews the progress of emergency care practice in this country from a general primary care system toward becoming an established specialty in hospital, prehospital, and private emergency care settings. It also describes aspects of undergraduate, postgraduate, and continuous emergency medicine education in the country. Further, a glimpse into academic emergency medicine and emergency nursing is provided. Since it describes a developing specialty, the article also attempts to address briefly major future challenges and their importance to the future development of the specialty in Oman

    The Arabian Sea as a high-nutrient, low-chlorophyll region during the late Southwest Monsoon

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    © The Authors, 2010. This article is distributed under the terms of the Creative Commons Attribution 3.0 License. The definitive version was published in Biogeosciences 7 (2010): 2091-2100, doi:10.5194/bg-7-2091-2010.Extensive observations were made during the late Southwest Monsoon of 2004 over the Indian and Omani shelves, and along a transect that extended from the southern coast of Oman to the central west coast of India, tracking the southern leg of the US JGOFS expedition (1994–1995) in the west. The data are used, in conjunction with satellite-derived data, to investigate long-term trends in chlorophyll and sea surface temperature, indicators of upwelling intensity, and to understand factors that control primary production (PP) in the Arabian Sea, focussing on the role of iron. Our results do not support an intensification of upwelling in the western Arabian Sea, reported to have been caused by the decline in the winter/spring Eurasian snow cover since 1997. We also noticed, for the first time, an unexpected development of high-nutrient, low-chlorophyll condition off the southern Omani coast. This feature, coupled with other characteristics of the system, such as a narrow shelf and relatively low iron concentrations in surface waters, suggest a close similarity between the Omani upwelling system and the Peruvian and California upwelling systems, where PP is limited by iron. Iron limitation of PP may complicate simple relationship between upwelling and PP assumed by previous workers, and contribute to the anomalous offshore occurrence of the most severe oxygen (O2) depletion in the region. Over the much wider Indian shelf, which experiences large-scale bottom water O2-depletion in summer, adequate iron supply from reducing bottom-waters and sediments seems to support moderately high PP; however, such production is restricted to the thin, oxygenated surface layer, probably because of the unsuitability of the O2-depleted environment for the growth of oxygenic photosynthesizers.Financial support was provided by CSIR through the Network Project CMM0009 to SWAN and by NSF through OCE-0327227S to JWM

    Reliability, availability, maintainability and safety (rams) in railway’s assurance system and implementation challenges : A Review

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    RAMS forms an integral part of railway’s system assurance. It integrates reliability engineering, availability or performance calculation, maintenance strategies and system safety. While RAMS is widely implemented in other industries like petroleum, aviation and chemical, the practice in railway is relatively new. RAMS task needs to be implemented from earliest phase of system design, tendering, project execution, operation up to decommissioning. Due to its compulsory extensive involvement of railway personnel as well as authorities, RAMS is not being fully utilized as an assurance tool in railway industry. This paper will introduce the core components of RAMS and their stakeholder

    Impacts of contrasting light on bud burst and on RwMAX1 and RwMAX2 expression in rose

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    Bud burst is a crucial factor in plant architecture and is strongly induced by light. In Rosa sp., this light effect was correlated with the growth of axillary buds and RwMAX1 and RwMAX2 expression within buds. In this paper, we investigated whether strigolactone pathway is involved in the regulation of axillary bud in response to light intensity. Hence, young roses were subjected to two contrasting light intensity regimes: high/high and high/low. The phenotype was characterized in both conditions and the expression of RwMAX1 and RwMAX2 genes was measured in the basal, middle and apical parts of rose primary branch. Light treatments showed a strong impact on axillary bud. The percentage of bud burst was severely reduced in the treatment high/low compared to the treatment high/high in all branch parts. In addition, the expression of RwMAX1 and RwMAX2 was strongly inhibited by high/high light regime and was conversely correlated with the rate of bud burst. In in vitro-grown axillary buds supplied with sucrose, glucose and fructose, RwMAX1 expression was significantly stimulated whereas that of RwMAX2 was significantly inhibited. Our results suggest that although RwMAX1 and RwMAX2 expression can be regulated by light, this expression does not explain the ability of bud burst

    Insight into the Role of Sugars in Bud Burst Under Light in the Rose

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    Bud burst is a decisive process in plant architecture that requires light in Rosa sp. This light effect was correlated with stimulation of sugar transport and metabolism in favor of bud outgrowth. We investigated whether sugars could act as signaling entities in the light-mediated regulation of vacuolar invertases and bud burst. Full-length cDNAs encoding two vacuolar invertases (RhVI1 and RhVI2) were isolated from buds. Unlike RhVI2, RhVI1 was preferentially expressed in bursting buds, and was up-regulated in buds of beheaded plants exposed to light. To assess the importance of sugars in this process, the expression of RhVI1 and RhVI2 and the total vacuolar invertase activity were further characterized in buds cultured in vitro on 100 mM sucrose or mannitol under light or in darkness for 48 h. Unlike mannitol, sucrose promoted the stimulatory effect of light on both RhVI1 expression and vacuolar invertase activity. This up-regulation of RhVI1 was rapid (after 6 h incubation) and was induced by as little as 10 mM sucrose or fructose. No effect of glucose was found. Interestingly, both 30 mM palatinose (a non-metabolizable sucrose analog) and 5 mM psicose (a non-metabolizable fructose analog) promoted the light-induced expression of RhVI1 and total vacuolar invertase activity. Sucrose, fructose, palatinose and psicose all promoted bursting of in vitro cultured buds under light. These findings indicate that soluble sugars contribute to the light effect on bud burst and vacuolar invertases, and can function as signaling entities
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