2,852 research outputs found

    Elements of paradoxes in supply chain management literature: A systematic literature review

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    This study reports the results of a systematic literature review investigating paradoxes in supply chain management. This issue is important because supply chain practitioners frequently face paradoxes in industry with little direction provided in supply chain literature. Investigating the years 1997 through 2019, we identified 64 articles as the basis of our research containing a total of 68 unique paradoxes. In identifying the paradox elements (PEs), we adopted paradox theory (PT) as the base theoretical approach, which was utilized in only 7 of the articles. We employed contingency theory, institutional complexity theory, and complexity theory to support our findings. For each paradox, we also extracted and summarized managerial insights for practitioners. This study addresses the emergent needs of investigating paradoxes in the supply chain management domain to extend the use of PT and complementary theories that can aid practitioners in how to efficiently manage the paradoxes they encounter in industry

    Interactions in sustainable supply chain management: a framework review

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    Purpose ā€“ This study evaluates the research conducted among the interim, dyadic interactions that bridge the stand-alone measures of economic, environmental, and social performance and the level of sustainability, as suggested in the Carter & Rogers (2008) framework. Design/methodology/approach ā€“ This paper conducts a systematic literature review based on the Tranfield et al. (2003) method of the articles published in 13 major journals in the area of supply chain management between the years of 2010 and 2016. Results were analyzed using an expert panel. Findings ā€“ The area of research between environmental and social performance is sparse and relegated to empirical investigation. As an important area of interaction, this area needs more research to answer the how and why questions. The economic activity seems to be the persistent theme among the interactions. Research implications ā€“ The literature on the ā€œESā€ interactions is lacking in both theoretical and analytical content. Studies explaining the motivations, optimal levels, and context that drive these interactions are needed. The extant research portrays economic performance as if it cannot be sacrificed for social welfare. This approach is not in line with the progressive view of SSCM but instead the binary view with an economic emphasis. Practical implications ā€“ To improve sustainability, organizations need the triple bottom line (TBL) framework that defines sustainability in isolation. However, they also need to understand how and why these interactions take place that drive sustainability in organizations. Originality/value ā€“ This is the first study to examine the literature specifically dedicated to the essential, interim, dyadic interactions that bridge the gap between stand-alone performance and the TBL that creates true sustainability. It also shows how the literature views the existence of sustainability is progressive, but many describe sustainability as binary. It is possible that economic sustainability is binary, and progressive characterizations of SSCM could be the reason behind the results favoring economic performance over environmental and social

    Monoamine Neurotransmitters as Substrates for Novel Tick Sulfotransferases, Homology Modeling, Molecular Docking, and Enzyme Kinetics

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    Blacklegged ticks (Ixodes scapularis) transmit the causative agent of Lyme disease in the Northeastern United States. Current research focuses on elucidating biochemical pathways that may be disrupted to prevent pathogen transmission, thereby preventing disease. Genome screening reported transcripts coding for two putative sulfotransferases in whole tick extracts of the nymphal and larval stages. Sulfotransferases are known to sulfonate phenolic and alcoholic receptor agonists such as 17Ī²-estradiol, thereby inactivating the receptor ligands. We used bioinformatic approaches to predict substrates for Ixosc Sult 1 and Ixosc Sult 2 and tested the predictions with biochemical assays. Homology models of 3D protein structure were prepared, and visualization of the electrostatic surface of the ligand binding cavities showed regions of negative electrostatic charge. Molecular docking identified potential substrates including dopamine, R-octopamine and S-octopamine, which docked into Ixosc Sult 1 with favorable binding affinity and correct conformation for sulfonation. Dopamine, but not R- or S-octopamine, also docked into Ixosc Sult 2 in catalytic binding mode. The predictions were confirmed using cytosolic fractions of whole tick extracts. Dopamine was a good substrate (Km = 0.1āˆ’0.4 Ī¼M) for the native Ixodes scapularis sulfotransferases from larval and nymphal stages regardless of their fed/unfed status. Octopamine sulfonation was detected only after feeding when gene expression data suggests that Ixosc Sult 1 is present. Because dopamine is known to stimulate salivation in ticks through receptor stimulation, these results imply that the function(s) of Ixosc Sult 1 or 2 may include inactivation of the salivation signal via sulfonation of dopamine and/or octopamine

    Molecular characterization of novel sulfotransferases from the tick, Ixodes scapularis

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    <p>Abstract</p> <p>Background</p> <p><it>Ixodes scapularis</it>, commonly known as the blacklegged or deer tick, is the main vector of Lyme disease in the United States. Recent progress in transcriptome research has uncovered hundreds of different proteins expressed in the salivary glands of hard ticks, the majority of which have no known function, and include many novel protein families. We recently identified transcripts coding for two putative cytosolic sulfotransferases in these ticks which recognized phenolic monoamines as their substrates. In this current study, we characterize the genetic expression of these two cytosolic sulfotransferases throughout the tick life cycle as well as the enzymatic properties of the corresponding recombinant proteins. Interestingly, the resultant recombinant proteins showed sulfotransferase activity against both neurotransmitters dopamine and octopamine.</p> <p>Results</p> <p>The two sulfotransferase genes were coded as <it>Ixosc </it>SULT 1 & 2 and corresponding proteins were referred as <it>Ixosc </it>Sult 1 and 2. Using gene-specific primers, the sulfotransferase transcripts were detected throughout the blacklegged tick life cycle, including eggs, larvae, nymphs, adult salivary glands and adult midgut. Notably, the mRNA and protein levels were altered upon feeding during both the larval and nymphal life stages. Quantitative PCR results confirm that <it>Ixosc </it>SULT1 was statistically increased upon blood feeding while <it>Ixosc </it>SULT 2 was decreased. This altered expression led us to further characterize the function of these proteins in the Ixodid tick. The sulfotransferase genes were cloned and expressed in a bacterial expression system, and purified recombinant proteins <it>Ixosc </it>Sult 1(R) and 2(R) showed sulfotransferase activity against neurotransmitters dopamine and octopamine as well as the common sulfotransferase substrate <it>p-</it>nitrophenol. Thus, dopamine- or octopamine-sulfonation may be involved in altering the biological signal for salivary secretion in <it>I. scapularis.</it></p> <p>Conclusions</p> <p>Collectively, these results suggest that a function of <it>Ixosc </it>Sult 1 and Sult 2 in <it>Ixodid </it>tick salivary glands may include inactivation of the salivation signal via sulfonation of dopamine or octopamine.</p

    Efficient utilization of DSPs and BRAMs revisited : new AES-GCM recipes on FPGAs

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    In 2008, Drimer et al. proposed different AES implementations on a Xilinx Virtex-5 FPGA, making efficient use of the DSP slices and BRAM tiles available on the device. Inspired by their work, we evaluate the feasibility of extending AES with the popular GCM mode of operation, still concentrating on the optimal use of DSP slices and BRAM tiles. We make use of a Xilinx Zynq UltraScale+ MPSoC FPGA with improved DSP features. For the AES part, we implement Drimer's round-based and unrolled pipelined architectures differently, still using DSPs and BRAMs efficiently based on the AES Tbox approach. On top of AES, we append the GCM mode of operation, where we use DSP slices to support the GCM finite field multiplication. This allows us to implement AES-GCM with a small amount of FFs and LUTs. We propose two implementations: A relatively compact round-based design and a faster unrolled design

    Secondary metabolites of Phlomis viscosa and their biological activities

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    Further phytochemical studies on the aerial parts of Phlomis viscosa (Lamiaceae) led to the isolation of 24 compounds: 3 iridoid glycosides, 10 phenylethanoid glycosides, a megastigmane glycoside and a hydroquinone glycoside, as well as 2 lignan glucosides and 7 neolignan glucosides, 1 of which is new (17b). Compound 17b was obtained as a minor component of an inseparable mixture (2:1) of 2 neolignan glucosides (17a/b), and characterized as 3',4-O-dimethylcedrusin 9-O-b -glucopyranoside. Full NMR data of the known 8-O-4' neolignan glucoside, erythro-1-(4-O-b-glucopyranosyl-3-methoxyphenyl)- 2-{2-methoxyl-4-[1-(E)-propene-3-ol]-phenoxyl}-propane-1,3-diol (18) are also reported. All isolated compounds were screened for cell growth inhibition versus 3 tumor cell lines (MCF7, NCI-H460, and SF-268) and several phenylethanoid glycosides were found to possess weak antitumoral activity. The phenylethanoid glycosides were also evaluated for their free radical (DPPH) scavenging, antibacterial and antifungal activities. The free radical (DPPH) scavenging activities of verbascoside (4), isoacteoside (5), forsythoside B (10), myricoside (13) and samioside (14) were found to be comparable to that of dl-a -tocopherol. Compounds 4, 5, 10 and 14 (MIC: 500 m g/mL) as well as Leucosceptoside A (8) and 13 (MIC:1000 m g/mL) showed very weak activity against Gram (+) bacteria

    Using Zebrafish for Investigating the Molecular Mechanisms of Drug-Induced Cardiotoxicity

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    Over the last decade, the zebrafish (Danio rerio) has emerged as amodel organismfor cardiovascular research.Zebrafish have several advantages over mammalian models. For instance, the experimental cost of using zebrafish is comparatively low; the embryos are transparent, develop externally, and have high fecundity making them suitable for large-scale genetic screening. More recently, zebrafish embryos have been used for the screening of a variety of toxic agents, particularly for cardiotoxicity testing. Zebrafish has been shown to exhibit physiological responses that are similar to mammals after exposure to medicinal drugs including xenobiotics, hormones, cancer drugs, and also environmental pollutants, including pesticides and heavy metals. In this review, we provided a summary for recent studies that have used zebrafish to investigate themolecularmechanisms of drug-induced cardiotoxicity. More specifically, we focused on the techniques that were exploited by us and others for cardiovascular toxicity assessment and described several microscopic imaging and analysis protocols that are being used for the estimation of a variety of cardiac hemodynamic parameters.Huseyin C. Yalcin is supported by Qatar National Research Fund (QNRF), National Priority Research Program NPRP 10-0123-170222,and Qatar University internal funds,QUUGBRC-2017-3 and QUST-BRC-SPR\2017-1. The publication of this article was partially funded by the Qatar National Library
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