667 research outputs found

    Calibration of Multicurrency LIBOR Market Models

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    This paper presents a methodf or calibrating a multi currency lognormal LIBOR Market Model to market data of at-the-money caps, swaptions and FX options. By exploiting the fact that multivariate normal distributions are invariant under orthonormal transformations, the calibration problem is decomposed into manageable stages, while maintaining the ability to achieve realistic correlation structures between all modelled market variables.currency options; LIBOR market model; exchange rate risk; interest rate risk

    Cholate-interspersed porphyrin-anthraquinone conjugates: photonuclease activity of large sized, 'tweezer-like' molecules

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    In a new approach towards the development of a 'dual-wavelength dual-mechanism' type of photosensitizer for use in photodynamic therapy (PDT), covalently linked bichromophoric systems comprising of porphyrin (P) and anthraquinone (AnQ) subunits have been synthesized and fully characterized by FAB-MS, IR, UV-Visible and 1H NMR methods. The porphyrin donor and the anthraquinone acceptor subunits of these mono- or bis-intercalating hybrid molecules are interspersed with either cholate or polymethylene spacers. There exists minimal ground- and singlet-state interaction between the porphyrin and anthraquinone subunits in the giant-sized, cholate-interspersed P-AnQ systems as revealed by a comparison of their spectroscopic and electrochemical properties with those of the corresponding individual reference compounds. On the other hand, quenching of fluorescence observed for the P-AnQ systems endowed with polymethylene spacers has been interpreted in terms of a possible intramolecular electron transfer between the singlet porphyrin and the anthraquinone acceptor. When excited into their porphyrin absorption band maxima, each new P-AnQ system could generate singlet molecular oxygen in good-to-moderate yield. Wavelength-dependent photonuclease activity of these new bis-intercalating species has been examined

    Observation of the hepatoprotective and antioxidant activities of Trianthema decandra Linn. (Vallai sharunnai) roots on carbon tetrachloride-treated rats

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    The present study was carried out to observe the hepatoprotective effect and antioxidant activity of the ethanol extract of the roots of Trianthema decandra Linn. (200 and 400 mg/kg) in rats treated with carbon tetrachloride for 8 weeks. Extract at the tested doses restored the levels of all serum (aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total bilirubin and total protein) and liver homogenate enzymes (glutathione peroxidase, glutathione reductase, superoxide dismutase and catalase) significantly. Histology demonstrated profound steatosis degeneration and nodule formation were observed in the hepatic architecture of carbon tetrachloride treated rats which were found to acquire near-normalcy in extract plus carbon tetrachloride administrated rats, and supported the biochemical observations. This study suggests that ethanol extract of T. decandra has a liver protective effect against carbon tetrachloride- induced hepatotoxicity and possess antioxidant activities

    Bioactivity in Echinoderms

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    Man in his pursuit for knowledge of newer and better drugs for eradicating diseases to which he is prone to has turned to the sea, which is a more potential treasure house of drugs due to its vast and diverse range of marine life. Many marine organisms exhibit toxicity as well as bioactivity. Some are toxic and lethal to terrestrial animals as well as to the man. The Phylum Echinodermata consists of sea cucumbers (holothurians), star lishes and sea urchins. These are known for their toxicity. This report deals with the results of the screening of 10 species of echinoderms collected from Gulf of Mannar area for biotoxicity to fishes and mice and also for hemolytic activity. The results showed that all the parts of Holothuria atra H. spinifera and Behadschia marmorata exhibited a high degree of toxicity to fish fingerlings and mice and also destructive action on erythrocyte cells

    Bloch Approximation in Homogenization and Applications

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    The classical problem of homogenization of elliptic operators with periodically oscillating coefficients is revisited in this paper. As is well known, the homogenization process in a classical framework is concerned with the study of asymptotic behavior of solutions uεu^\varepsilon of boundary value problems associated with such operators when the period ε>0\varepsilon>0 of the coefficients is small. In a previous work by C. Conca and M. Vanninathan [SIAM J. Appl. Math., 57 (1997), pp. 1639--1659], a new proof of weak convergence as ε0\varepsilon\to 0 towards the homogenized solution was furnished using Bloch wave decomposition. Following the same approach here, we go further and introduce what we call Bloch approximation, which will provide energy norm approximation for the solution uεu^\varepsilon. We develop several of its main features. As a simple application of this new object, we show that it contains both the first and second order correctors. Necessarily, the Bloch approximation will have to capture the oscillations of the solution in a sharper way. The present approach sheds new light and offers an alternative for viewing classical results

    The import substituted poultry industry; evidence from Ghana

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    Rapid growth in Ghana’s poultry imports revealed the weaknesses of the domestic industry in competing with imported products. Establishment of an intensive poultry system as a benchmark for examining the performance poultry production and marketing in addition to interviews with poultry stakeholders revealed the constraints in the poultry industry in Ghana. Results emphasized that Feed Conversion Rate is a major factor in reducing production cost and improving the broilers growth efficiency. The BNARI feed conversion rate for the broiler is 1.56 Kilogram of feed needed to produce 1 kg live weight compared to 2.12 kg of feed to produce 1 kg live weight by other poultry farmers engaged in the study. Feed costs represent more than 70% of the total cost of broilers production, and feed utilization efficiency, are critical for the growth rate of broilers. A major constraint is the lack of protection on the infant poultry industry by the Ghana government leading to unfair competition with cheap imported poultry products, which is 30-40 percent cheaper and undermines the growth of the local industry. Other constraints are high feed cost, high chick mortality as a result electricity power outage for brooding, feed and water contamination and consumer preference for imported poultry meat. There is still 74% demand market share to be fulfilled. The Ghana poultry industry is insecure because poultry farms are collapsing faster than new farms are being established or old farms are being expanded. There is a need for serious intervention by the government through policies and enforcements to reverse this trend.Kwamina Ewur. Banson, Gobinath Muthusamy, Ebenezer Kond

    PRODUCTION AND PURIFICATION OF ANGIOTENSIN-CONVERTING ENZYME INHIBITOR BY SELECTED BACTERIAL STRAIN FOR CANCER THERAPY

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    Objective: The present study was planned to explore safer, innovative and economic Angiotensin-converting enzyme inhibitors (ACEi) from beef extract by the action of a proteolytic Micrococcus luteus. Cytotoxicity of the stable peptide was predicted using MCF-7 cell line in vitro.Methods: ACEi was purified by sequential steps of ethanol precipitation, ion exchange column chromatography (MonoQ) and gel filtration column chromatography (Sephadex G25). The apparent molecular mass was determined by SDS-PAGE. The anticancer property was analyzed by studying the cytotoxicity effects of angiotensin converting enzyme inhibitor using Breast cancer MCF-7 cell linesResults: The peptide was purified and molecular mass was determined as 4.5 kDa. The IC50 value of peptide was found to be 59.5 µg/ml. The DNA fragmentation was not observed in the treated cells. The purified peptide has demonstrated to induce apoptosis of cancer cell. The results proved that the peptide has the ability to be used for cancer therapy.Conclusion: The presence of ACE inhibition activities in the fermentation of beef extract using Micrococcus luteus has been investigated. The Peptide has been determined as an active compound that inhibited the activity of ACE. These properties indicate the possibilities of the use of purified protein as a potent anticancer agent.Keywords: Angiotensin-converting enzyme inhibitors, Micrococcus luteus, Anti-proliferative, Anti-metastatic, MCF-7 cell line, Anticancer activity

    Bioactivity in marine algae

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    Marine algae have been reponed to possess a wide range of bio active properties (Hashimoto 1979, Baslow 1969, Hoppe, et al. 1979, Hoppe et al. 1984, Blunden et al. 1981, Cocamese et al. 1981, Ramamurthy et al. 1967, Mc Lachan 1964, Byrkholder and Sharma 1969. Conover and Sieburth 1964, Garber et al. 1958). Quite recently, Naqvi et al. (1980) studied the bioactivities of 25 species of marine algae and sea grasses collected mainly from the North Eastern coast of India and a few from the coast of Tamil Nadu

    ISOLATION OF ANGIOTENSIN-CONVERTING ENZYME INHIBITOR PRODUCING BACTERIA FROM COW MILK

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    Objective: To evaluate the potential of protease producing organism for the production of Angiotensin I–converting enzyme (ACE) inhibitor by fermentation of various protein substrates.Methods: Bacterial strains were isolated from cow milk collected in Coimbatore, Tamil Nadu, India by using serial dilution technique, plated on nutrient agar medium. The identity of the strain was ascertained by 16s rRNA gene sequencing method and was submitted to the NCBI GenBank nucleotide database. Various substrates were screened for ACE inhibitor production by the fermentation with the isolated strain.Results: The isolated coded as BUCTL09, which showed a significant zone of clearance was selected and identified as Micrococcus luteus (KF303592.1). Among the seven substrates, only beef extract fermented broth showed an inhibition of 79% and was reported as the best substrate.Conclusion: In the search for non-toxic, and economic ACE inhibitors as an alternative to the synthetic drugs, many natural ACE inhibitors have been isolated from a microbial source. In the present study, isolate BUCTL09 was selected for the production of ACE inhibitor from the beef extract. Findings from this study lead us to investigate this potent ACE inhibitor further for its biological properties and to explore the impending efficacy of the ACE inhibitor which may conceivably be developed into a prospective drug
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