417 research outputs found

    A Closed-Form Approximated Expression for the Residual ISI Obtained by Blind Adaptive Equalizers with Gain Equal or Less than One

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    In this paper we propose for the real and two independent quadrature carrier case, a closed-form approximated expression for the achievable residual Inter-Symbol Interference (ISI) that depends on the step-size parameter, equalizer’s tap length, equalized output gain, input signal statistics, channel power and SNR. This expression is valid for blind adaptive equalizers, where the error that is fed into the adaptive mechanism which updates the equalizer‘s taps can be expressed as a polynomial function of order three of the equalized output and where the gain between the input and equalized output signal is less than or equal to one, as is in the case of Godard (gain = 1) and WNEW (gain < 1) algorithm. Since the channel power is measurable or can be calculated if the channel coefficients are given, there is no need to carry out simulation with various step-size parameters in order to reach the required residual ISI. In addition, we show two new equalization methods (gain dependent), which have shown to have improved equalization performance compared to Godard and WNEW

    The isolation and structural elucidation of voacristine hydroxyindolenine

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    Isolation and characterization of voacristine hydroxyindolenin

    Willow Leaves' Extracts Contain Anti-Tumor Agents Effective against Three Cell Types

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    Many higher plants contain novel metabolites with antimicrobial, antifungal and antiviral properties. However, in the developed world almost all clinically used chemotherapeutics have been produced by in vitro chemical synthesis. Exceptions, like taxol and vincristine, were structurally complex metabolites that were difficult to synthesize in vitro. Many non-natural, synthetic drugs cause severe side effects that were not acceptable except as treatments of last resort for terminal diseases such as cancer. The metabolites discovered in medicinal plants may avoid the side effect of synthetic drugs, because they must accumulate within living cells. The aim here was to test an aqueous extract from the young developing leaves of willow (Salix safsaf, Salicaceae) trees for activity against human carcinoma cells in vivo and in vitro. In vivo Ehrlich Ascites Carcinoma Cells (EACC) were injected into the intraperitoneal cavity of mice. The willow extract was fed via stomach tube. The (EACC) derived tumor growth was reduced by the willow extract and death was delayed (for 35 days). In vitro the willow extract could kill the majority (75%–80%) of abnormal cells among primary cells harvested from seven patients with acute lymphoblastic leukemia (ALL) and 13 with AML (acute myeloid leukemia). DNA fragmentation patterns within treated cells inferred targeted cell death by apoptosis had occurred. The metabolites within the willow extract may act as tumor inhibitors that promote apoptosis, cause DNA damage, and affect cell membranes and/or denature proteins

    Chemopreventive potential of ÎČ-Sitosterol in experimental colon cancer model - an In vitro and In vivo study

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    <p>Abstract</p> <p>Background</p> <p><it>Asclepias curassavica </it>Linn. is a traditional medicinal plant used by tribal people in the western ghats, India, to treat piles, gonorrhoea, roundworm infestation and abdominal tumours. We have determined the protective effect of ÎČ-sitosterol isolated from <it>A. curassavica </it>in colon cancer, using <it>in vitro </it>and <it>in vivo </it>models.</p> <p>Methods</p> <p>The active molecule was isolated, based upon bioassay guided fractionation, and identified as ÎČ-sitosterol on spectral evidence. The ability to induce apoptosis was determined by its <it>in vitro </it>antiradical activity, cytotoxic studies using human colon adenocarcinoma and normal monkey kidney cell lines, and the expression of ÎČ-catenin and proliferating cell nuclear antigen (PCNA) in human colon cancer cell lines (COLO 320 DM). The chemopreventive potential of ÎČ-sitosterol in colon carcinogenesis was assessed by injecting 1,2-dimethylhydrazine (DMH, 20 mg/kg b.w.) into male Wistar rats and supplementing this with ÎČ-sitosterol throughout the experimental period of 16 weeks at 5, 10, and 20 mg/kg b.w.</p> <p>Results</p> <p>ÎČ-sitosterol induced significant dose-dependent growth inhibition of COLO 320 DM cells (IC<sub>50 </sub>266.2 ÎŒM), induced apoptosis by scavenging reactive oxygen species, and suppressed the expression of ÎČ-catenin and PCNA antigens in human colon cancer cells. ÎČ-sitosterol supplementation reduced the number of aberrant crypt and crypt multiplicity in DMH-initiated rats in a dose-dependent manner with no toxic effects.</p> <p>Conclusion</p> <p>We found doses of 10-20 mg/kg b.w. ÎČ-sitosterol to be effective for future <it>in vivo </it>studies. ÎČ-sitosterol had chemopreventive potential by virtue of its radical quenching ability <it>in vitro</it>, with minimal toxicity to normal cells. It also attenuated ÎČ-catenin and PCNA expression, making it a potential anticancer drug for colon carcinogenesis.</p

    A Distinct Translation Initiation Mechanism Generates Cryptic Peptides for Immune Surveillance

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    MHC class I molecules present a comprehensive mixture of peptides on the cell surface for immune surveillance. The peptides represent the intracellular protein milieu produced by translation of endogenous mRNAs. Unexpectedly, the peptides are encoded not only in conventional AUG initiated translational reading frames but also in alternative cryptic reading frames. Here, we analyzed how ribosomes recognize and use cryptic initiation codons in the mRNA. We find that translation initiation complexes assemble at non-AUG codons but differ from canonical AUG initiation in response to specific inhibitors acting within the peptidyl transferase and decoding centers of the ribosome. Thus, cryptic translation at non-AUG start codons can utilize a distinct initiation mechanism which could be differentially regulated to provide peptides for immune surveillance

    Re-thinking Regionalism: Europe and East Asia in Comparative Historical Perspective

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    Regionally-based processes of political and economic integration, security cooperation, and even social identification have become increasingly important and prominent parts of the international system. Nowhere have such processes gone further than in Western Europe. Somewhat surprisingly, similar patterns of regional integration have been steadily developing in East Asia - a region many observers consider unlikely to replicate the European experience. What are the factors that encourage regional political cooperation and economic integration? Are there common forces encouraging such outcomes in very different geographical areas and at very different moments in history? This paper uses an historically grounded comparative approach to examine the historical pre-conditions that underpinned the formation of the European Union, and then contrasts them with the situation in East Asia today. While the overall geopolitical and specific national contexts are very different, the East Asian experience may ultimately generate relationships and structures that are more like the European Union's than some of the sceptics imagine

    How do religious norms diffuse? Institutional translation and international change in a post-secular world society

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    This article draws from Habermasian post-secular theory to broaden the scope of Constructivist research on norm dynamics beyond its current Western-centric focus. In an increasingly post-secular world society, we conceptualize the mechanism of institutional translation to explain processes of norm diffusion whereby culturally situated ‘thick’ norms acquire a ‘thinner’ ethical status via a dialogical process of normative contestation across diverse ethical perspectives. Institutional translation differs from, but also complements, mechanisms of norm diffusion, such as persuasion and localization, by illustrating how norms conceived and promoted by non-Western religious-based actors can acquire global legitimacy within the institutions of the international liberal order. The article investigates the explanatory value of this framework through an empirical analysis of two contrasting cases of norm promotion by the Organization of Islamic Conference at the United Nations. The first case considers the global diffusion of the norm of dialogue of civilizations as an example of successful institutional translation. The second case illustrates the failed diffusion of the norm against th
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