46 research outputs found

    Two essays in computational optimization: computing the clar number in fullerene graphs and distributing the errors in iterative interior point methods

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    Fullerene are cage-like hollow carbon molecules graph of pseudospherical sym- metry consisting of only pentagons and hexagons faces. It has been the object of interest for chemists and mathematicians due to its widespread application in various fields, namely including electronic and optic engineering, medical sci- ence and biotechnology. A Fullerene molecular, Γ n of n atoms has a multiplicity of isomers which increases as N iso ∼ O(n 9 ). For instance, Γ 180 has 79,538,751 isomers. The Fries and Clar numbers are stability predictors of a Fullerene molecule. These number can be computed by solving a (possibly N P -hard) combinatorial optimization problem. We propose several ILP formulation of such a problem each yielding a solution algorithm that provides the exact value of the Fries and Clar numbers. We compare the performances of the algorithm derived from the proposed ILP formulations. One of this algorithm is used to find the Clar isomers, i.e., those for which the Clar number is maximum among all isomers having a given size. We repeated this computational experiment for all sizes up to 204 atoms. In the course of the study a total of 2 649 413 774 isomers were analyzed.The second essay concerns developing an iterative primal dual infeasible path following (PDIPF) interior point (IP) algorithm for separable convex quadratic minimum cost flow network problem. In each iteration of PDIPF algorithm, the main computational effort is solving the underlying Newton search direction system. We concentrated on finding the solution of the corresponding linear system iteratively and inexactly. We assumed that all the involved inequalities can be solved inexactly and to this purpose, we focused on different approaches for distributing the error generated by iterative linear solvers such that the convergences of the PDIPF algorithm are guaranteed. As a result, we achieved theoretical bases that open the path to further interesting practical investiga- tion

    WEB-BASED LANGUAGE CLUB AFFECTING EFL LEARNERS' PROFICIENCY: A CASE OF IRANIAN LEARNERS

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    Abstract: Language clubs have been reported to be effective in learning languages, increasing motivation and independence (Gao, 2009). The present study was an attempt to investigate the effect of a web-based language club on the language proficiency of Iranian EFL learners. A number of pre-intermediate learners form two universities (118) were selected among 154 through a test of proficiency (TOEFL PBL), then they were put into experimental and control groups. The participants in experimental group got on line and acted as a member of a virtual language club for a period of 6 months. They got involved with activities like emailing, chatting, and weblogging. Data were collected through TOEFL PBL. The analyzed data from the test of proficiency indicated the outperformance of those in experimental group. Consequently, it might be proposed that web-based language clubs can make language learning easier and more efficient.      Keywords: Web-based language club, English Proficiency, EFL learner

    The Fourth World and Politics of Social Identity in Margaret Atwood’s MaddAddam Trilogy

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    With the advent of the 21st century, the way characters and identities interact under the influence of dominant powers has brought a new world into existence, a world dubbed by Manuel Castells as the ‘Fourth World’. Within the Castellsian theoretical matrix of the Fourth World and politics of identity, the present study seeks to investigate the true nature of the futuristic world Margaret Atwood has created in the MaddAddam trilogy. The trilogy literarily reflects a global crisis that ultimately leads to dystopia and the destruction of the human race: what remains of humanity is a small group of survivors who must struggle to conserve what remains of humanity. Identity as the main determining factor in the Fourth World represents personal and public privileges, characteristics, and means of differentiating oneself from others. The Fourth World and its political peculiarities reflect contemporary powers, i.e. the power of the network society, network communication and media. Humankind, in this wheel, is just a toy in the hands of an intelligence broker. What exactly happens to human and semi-human characters in Atwood’s trilogy is the result of Fourth World structures and values, and how they shape and reconstruct identities to lead the world toward fabricated truths and values, and terminate in dystopia

    Variation in bioactive contents and anatomical characteristics of different fennel (<i>Foeniculum vulgare</i> Mill.) populations as affected by self-pollination

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    The production of self pollinated plant genotypes could be critical for improving medicinal plants. Pollination in Apiaceae family can also affect secondary metabolites. In this study, 23 fennel populations were used to assess the effect of self pollination on essential oil yield, antioxidant activity (based on three model system), total phenolic (TPC) and flavonoid content (TFC). First, some plant inflorescences were divided in two parts. Then the half was bagged and the second half was permitted for out crossing. The self and outcross pollinated seeds were sown in a randomized complete block design (RCBD) in three replicates. Results revealed that inbreeding led to increase in the secretary ducts number (9.36%) as well as essential oil yield (25.61%) in all fennel populations. Essential oil yield ranged from 2.4% to 6.4% in seeds produced via out crossing, while it varied from 3.5% to 6.5% in self pollinated ones. Furthermore, self pollination increased TPC (21.66%), TFC (49.40%) and antioxidant activity (6.23%). Among the populations derived from self pollinated seeds Tabriz showed the highest TFC (8.4 mgQUEg-1DW) and antioxidant activity (IC50=83.1μg/ml), whereas Semirom possessed the highest TPC (150 mgTAEg-1DW), respectively. In overall, self pollination can produce lead to the populations with higher amount of secondary metabolites

    Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

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    Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

    Comparative toxic effect of bulk zinc oxide (ZnO) and ZnO nanoparticles on human red blood cells

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    Metal oxide nanoparticles (NPs) are a member of nanomaterials family that have been produced on a large scale and their toxicity affected by their high surface-to-volume ratio. The hemolytic toxic effects of metal oxide NPs may be completely different from those observed in their bulk counterparts. So, the main purpose of this research was to measure the difference between the hemolytic effects of ZnO (NPs and bulk) on isolated human red blood cells (RBCs). Hemolysis was measured after incubation of human RBCs with 0.01-1 mM of ZnO (bulk and NPs) for 6 h. For measurement of other variables, human RBCs were treated with 0.1 mM of ZnO (NPs and bulk) for 1, 2, and 3 h. Our results demonstrate that bulk ZnO did not show any toxic effects in the concentrations tested, while ZnO NPs caused toxic hemolytic effects through formation of ROS, lipid peroxidation, and glutathione depletion
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