99 research outputs found

    X-Ray Spectral Study of AGN Sources Content in Some Deep Extragalactic XMM-Newton Fields

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    We undertake a spectral study of a sample of bright X-ray sources taken from six XMM-Newton fields at high galactic latitudes, where AGN are the most populous class. These six fields were chosen such that the observation had an exposure time more than 60 ksec, had data from the EPIC-pn detector in the full-Frame mode and lying at high galactic latitude ∣b∣>25o|b| > 25^o . The analysis started by fitting the spectra of all sources with an absorbed power-law model, and then we fitted all the spectra with an absorbed power-law with a low energy black-body component model.The sources for which we added a black body gave an F-test probability of 0.01 or less (i.e. at 99% confidence level), were recognized as sources that display soft excess. We perform a comparative analysis of soft excess spectral parameters with respect to the underlying power-law one for sources that satisfy this criterion. Those sources, that do not show evidence for a soft excess, based on the F-test probability at a 99% confidence level, were also fitted with the absorbed power-law with a low energy black-body component model with the black-body temperature fixed at 0.1 and 0.2 keV. We establish upper limits on the soft excess flux for those sources at these two temperatures. Finally we have made use of Aladdin interactive sky atlas and matching with NASA/IPAC Extragalactic Database (NED) to identify the X-ray sources in our sample. For those sources which are identified in the NED catalogue, we make a comparative study of the soft excess phenomenon for different types of systems

    Insights into seeds priming effects using a magnetic field and algal treatments on growth and productivity of faba bean under salinity stress conditions

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    Soil fertility and crop productivity in the Nile Delta are severely threatened by soil salinization. Hence, the development of reliable techniques to enhance the salinity tolerance of plants is an essential prerequisite for the desirable sustainable agricultural development in Egypt. In the present study, we evaluated the influence of seeds priming using a magnetic field (MF) at different exposure times (0, 15, 30, and 45 min), either alone or combined with seeds pre-soaking or foliar spraying with seaweed extracts of Hydroclathrus clathratus and Acanthophora spicifera. The effects on soil properties, growth, yield, and seed quality of Vicia faba grown in saline soil were assessed. Results indicated that MF-treated seeds (MFTS), either alone or coupled with seaweed treatments, distinctly improved soil characterization by decreasing EC and pH niches, and also increased the availability of soil macro- and micronutrient elements, particularly at MF long exposure time (≄30 min). MFTS and/or MFTS with seaweed treatments at 30 min improved soil fertility indices (CO2 evolution and nitrogenase activity) and induced the highest increases of macro- and micro-nutrient contents in seeds, plant growth and seed quality. Additionally, enhancement of chlorophyll a and b, carbohydrates and amino acids, and decreasing proline levels were the bases of salinity stress alleviation. Conclusively, seed priming in the MF coupled with foliar spraying of seaweed extracts could be a sustainable and affordable approach for cultivating V. faba plants under salinity stress conditions

    Why Do States Develop Multi-tier Emigrant Policies? Evidence from Egypt

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    Why do states vary their policies towards their citizens abroad, and why are some emigrant groups treated preferentially to others? The literature on the politics of international migration has yet to explore this as a separate field of inquiry, assuming that states adopt a single policy that encourages, sustains or prevents emigration abroad. Yet, in the case of Egypt, the state developed a multi-tiered policy that distinctly favoured specific communities abroad over others. I hypothesise that policy differentiation is based upon the perceived utility of the emigrant group remaining abroad versus the utility of its return. This utility is determined by two factors: the sending state’s domestic political economy priorities and its foreign policy objectives

    Mode of gene action and heterosis for physiological, biochemical, and agronomic traits in some diverse rice genotypes under normal and drought conditions

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    Water scarcity is a crucial environmental stress that constrains rice growth and production. Thus, breeding for developing high-yielding and drought-tolerant rice genotypes is decisive in sustaining rice production and ensuring global food security, particularly under stress conditions. To this end, this study was conducted to evaluate the effects of water deficit on 31 genotypes of rice (seven lines, viz., Puebla, Hispagran, IET1444, WAB1573, Giza177, Sakha101, and Sakha105, and three testers, viz., Sakha106, Sakha107, and Sakha108) and their 21 crosses produced by line × tester mating design under normal and water deficit conditions; this was to estimate the combining ability, heterosis, and gene action for some traits of physiological, biochemical, and yield components. This study was performed during the summer seasons of 2017 and 2018. The results showed that water deficit significantly decreased relative water content, total chlorophyll content, grain yield, and several yield attributes. However, osmolyte (proline) content and antioxidant enzyme activities (CAT and APX) were significantly increased compared with the control condition. Significant mean squares were recorded for the genotypes and their partitions under control and stress conditions, except for total chlorophyll under normal irrigation. Significant differences were also detected among the lines, testers, and line × tester for all the studied traits under both irrigation conditions. The value of the σÂČGCA variance was less than the value of the σÂČSCA variance for all the studied traits. In addition, the dominance genetic variance (σ2D) was greater than the additive genetic variance (σ2A) in controlling the inheritance of all the studied traits under both irrigation conditions; this reveals that the non-additive gene effects played a significant role in the genetic expression of the studied traits. The two parental genotypes (Puebla and Hispagran) were identified as good combiners for most physiological and biochemical traits, earliness, shortness, grain yield, and 1,000-grains weight traits. Additionally, the cross combinations Puebla × Sakha107, Hispagran × Sakha108, and Giza177 × Sakha107 were the most promising. These results demonstrated the substantial and desirable specific combining ability effects on all the studied traits, which suggested that it could be considered for use in rice hybrid breeding programs

    Effect of foliar application of nano-nutrients solution on growth and biochemical attributes of tomato (Solanum lycopersicum) under drought stress

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    IntroductionDrought stress has drastically hampered the growth and yield of many crops. Therefore, environmentally safe agricultural techniques are needed to mitigate drought stress impact. To this end, foliar spray of nano-nutrients solution to (NNS) alleviate harmful aspects of drought stress.MethodsIn a completely randomized design (CRD) experiment, seedlings were transplanted into pots at 2-3 leaf stage, each filled with loam-compost- organic manure soil (3:1:1). Plants were divided into two groups. (a) control group (b) applied stress group. Plants at vegetative stage were treated with 100% FC for control group and 60% FC for drought group, and these levels were maintained until harvesting. Three treatments of NNS with four levels i.e., 0%, 1%, 3% and 5% were given to all the pots after two weeks of drought stress treatment with a gap of 5 days at vegetative stage.Results and discussionApplication of 1% of nano-nutrient solution displayed an improvement in shoot length, shoot fresh and dry weight, number of leaves and flowers. Leaf chlorophylls and carotenoids and total phenolics contents were found maximum while minimum electrolyte leakage was observed at 3% application compared to control. Further, 1% application of NNS increased the Leaf RWC%, total soluble sugars, flavonoids contents. 5% NNS application exhibited higher total free amino acids with minimum lipid peroxidation rate in leaves of tomato under drought. Antioxidant enzyme activities increased in a concentration dependent manner as gradual increase was observed at 1%, 3% and 5%, respectively. Overall, this study introduced a new insights on using nano-nutrient solutions to maintain natural resources and ensure agricultural sustainabilit

    Egyptian Satirical Graphics on Social Media after the Arab Spring

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    This paper investigates Egyptian digital forms of satirical graphics mostly published on Social Media by cartoonists and amateurs after the Arab Spring. These include: webcomics memes, and Graphic Interchange Format (GIF). The paper will focus on two Facebook pages as a case study: Asa7be Sarcasm Society and Islam Gawish's Elwarka/The Paper. With this aim in mind, I will show how these forms of political satire incorporate, cinema, theatre, religion, western elements and pan-Arabism to express a political view in a creative manner to appeal to a more diverse and broad audience. The first part of the paper provides a brief discussion of Arabic/Egyptian satire with specific reference to political cartoons and Egyptian youth activism on social media (specifically Facebook). It will also introduce the concept of satirical graphics and some of its concrete applications. The second part describes the methodology and provides an analysis of the case study

    Angst Springs Eternal:Dangerous Times and the Dangers of Timing the “Arab Spring”

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    Various reflections on the ‘Arab Spring’ evince a common view of the relationship between change and time that imbues events with a sense of intrinsic peril. Based on a framework developed from Norbert Elias’s concept of timing, this article elaborates the relationship between time and the ‘Arab Spring’ by unpacking and explaining three rhetorical tropes prevalent in academic responses to the revolts. The first two construct a problem to which the third proffers a solution. First, analysts treat time itself as a problematic force confounding stability and progress. Second, they deploy fluvial metaphors to present dynamic events as inherently insecure. Third, they use temporal Othering to retrofit the ‘Arab Spring’ to the familiar arc of liberal democracy, which renders the revolts intelligible and amenable to external intervention. These moves prioritize certainty and order over other considerations and constrain open-ended transformations within a familiar rubric of political progress. They also constitute an active timing effort based on a conservative standard, with important implications for our understanding of security and for scholarly reflexivity. The article concludes with three temporal alternatives for engaging novel changes like the ‘Arab Spring’
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