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51.
We consider a continuous time multivariate financial market with proportional transaction costs and study the problem of finding the minimal initial capital needed to hedge, without risk, European-type contingent claims. The model is similar to the one considered in Bouchard and Touzi [B. Bouchard, N. Touzi, Explicit solution of the multivariate super-replication problem under transaction costs, The Annals of Applied Probability 10 (3) (2000) 685–708] except that some of the assets can be exchanged freely, i.e. without paying transaction costs. In this context, we generalize the result of the above paper and prove that the super-replication price is given by the cost of the cheapest hedging strategy in which the number of non-freely exchangeable assets is kept constant over time. Our proof relies on the introduction of a new auxiliary control problem whose value function can be interpreted as the super-hedging price in a model with unbounded stochastic volatility (in the directions where transaction costs are non-zero). In particular, it confirms the usual intuition that transaction costs play a similar role to stochastic volatility. 相似文献
52.
Hadji I Marzouki MN Ferraro D Fasano E Majdoub H Pani G Limam F 《Applied biochemistry and biotechnology》2007,143(2):129-141
Crude garlic extract contains one Mn-superoxide dismutase designated as SOD1 and two Cu,Zn superoxide dismutases as SOD2 and
SOD3. The major isoform SOD2 was purified to homogeneity by Sephacryl S200-HR gel filtration, DEAE Sepharose ion exchange
chromatography, and chromatofocusing using PBE 94. SOD2 was purified 82-fold with a specific activity of 4,960 U/mg protein.
This enzyme was stable in a broad pH range from 5.0 to 10.0 and at various temperatures from 25 to 60°C. The native molecular
mass of SOD2 estimated by high performance liquid chromatography on TSK gel G2000SW column was 39 kDa. Sodium dodecyl sulfate–polyacrylamide
gel electrophoresis analysis showed a single band near 18 kDa, suggesting that native enzyme was homodimeric. The isoelectric
point as determined by chromatofocusing was 5. Analysis of its N terminal amino acid sequence revealed high sequence homology
with several other cytosolic Cu,Zn-SODs from plants. Exposure of cancer cell lines to garlic Cu,Zn-SOD2 led to a significant
decrease in superoxide content with a concomitant rise in intracellular peroxides, indicating that the enzyme is active in
mammalian cells and could, therefore, be used in pharmacological applications. 相似文献
53.
Leila Kalai-Grami Sabrine Saidi Sarra Bachkouel Imen Ben Slimene Monia Mnari-Hattab Mohamed Rebah Hajlaoui Ferid Limam 《Applied biochemistry and biotechnology》2014,174(1):365-375
A collection of 200 bacterial isolates recovered from citrus plants (Citrus limon, Citrus sinensis, and Citrus reticulata), Medicago truncatula and Laurus nobilis, was established. In vitro screening indicated that 28 isolates exhibited an inhibitory activity against the vascular pathogens Phoma tracheiphila and Verticillium albo-atrum. Isolates were screened according to their hydrolytic activities, plant growth-promoting bacteria (PGPB) abilities, as well as for the presence of nonribosomal peptide synthetase (NRPS) genes responsible of the lipopeptide biosynthesis. The results were positive for 16 isolates which exhibited at least two PGPB activities and a single NRPS gene. Genetic diversity of the selected isolates was studied using random amplified polymorphic DNA (RAPD) and repetitive element PCR (REP) tools that showed clustering of strains into three major groups (I, II, and III) (i, ii, and iii), respectively. Clustering was further confirmed by the 16S rDNA sequencing that assigned nine isolates to Bacillus velezensis, four isolates to Bacillus methyltrophicus, one isolate to Bacillus amyloliquefaciens, and two isolates to Bacillus mojavensis. Organ-bacterial genotype interaction as well as positive correlation with NRPS genes are discussed. 相似文献
54.
Tabbene O Ben Slimene I Bouabdallah F Mangoni ML Urdaci MC Limam F 《Applied biochemistry and biotechnology》2009,157(3):407-419
B38 bacterial strain, isolated from Tunisian soil showed a strong antimicrobial activity. Based on biochemical characterization
and 16S rDNA sequence analysis, B38 strain was identified as Bacillus subtilis. Cell culture supernatant showed antibacterial activity against clinical isolates of methicillin-resistant Staphylococcus species and several Gram-positive and Gram-negative bacteria. Antifungal activity against phytopathogenic fungi was also
observed. Antibacterial activity production started at early exponential growth phase, and maximum activity was reached at
the stationary phase. This antibacterial activity was neither affected by proteases, lipase, and organic solvents, nor by
surfactants. It was stable over a wide pH range and still active after autoclaving at 121 °C during 20 min. Thin layer chromatography
followed by bioautography assay allowed the detection of four active spots with R
f values of 0.30, 0.47, 0.70, and 0.82. The single spot with R
f 0.30 showed antifungal activity, whereas the spots with R
f values of 0.47, 0.70, and 0.82 exhibited antibacterial activity. 相似文献
55.
This article has been retracted. 相似文献
56.
H. Mosbahi M. Gassoumi Imen Saidi Houcine Mejri C. Gaquière M.A. Zaidi H. Maaref 《Current Applied Physics》2013,13(7):1359-1364
AlGaN/GaN/Si HEMTs grown by molecular beam epitaxy have been investigated using spectroscopy capacitance, direct and pulse current–voltage and small-signal microwave measurements. Passivation of the HEMT devices by SiO2/SiN with NH3 and N2O pretreatments is made in order to reduce the trapping effects. As has been found from DLTS data, some of electron traps are eliminated after passivation. This has led to an improvement in the drain current. To describe the electron transport, we have developed a charge-control model by including the deep traps observed from DLTS experiments. The thermal and trapping effects have been, on the other hand, studied from a comparison between direct-current and pulsed conditions. As a result, a gate-lag and a drain-lag were revealed indicating the presence of deep lying centers in the gate-drain spacing. Finally, small-signal microwave results have shown that the radio-frequency parameters of the AlGaN/GaN/Si transistors are improved by SiO2/SiN passivation and more increasingly with N2O pretreatment. 相似文献
57.
Synthesis and characterisation of poly(ester-amide)s from aromatic bisoxazoline precursors 总被引:1,自引:0,他引:1
A series of novel aliphatic aromatic poly(ester-amide)s (PEA) have been synthesized by condensation reaction of aromatic bisoxazolines with aliphatic dicarboxylic compounds. These polymers have a number average molecular weight of 20,000-25,000. Depending of the aromatic structure of the bisoxazoline precursor, they are either amorphous or semi-crystalline. A good solubility in aprotic solvents was observed for all PEAs. 相似文献
58.
Two inorganic compounds entitled tetrasodium hexaaquacobalt decavanadate tetraco-sahydrate,(I), and diammonium bis[hexaaquamanganese] decavanadate tetrahydrate,(II), have been isolated by conventional solution method and structurally characterized by single-crystal X-ray diffraction methods, scanning electron microscopy, IR spectra, thermal analyses and cyclic voltammetry measurements. They crystallize with triclinic (P-1) symmetry and consists of a centrosymmetric [V10O28]6? anion. The Co2+ and Mn2+ cations in (I) and (II) respectively are octahedrally coordinated by six water molecules. Compound (I) also contains a polymeric linear array of edge-sharing [Na(OH2)6]+ and [Co(OH2)6]2+ octahedra and compound (II) exhibit a catenary structure consisting of [V10O28]6? anions linked to [Mn(OH2)6]2+ and NH4 +via hydrogen bonds. 相似文献
59.
This Note is concerned with the severely ill-posed Cauchy–Stokes problem. This inverse problem is rephrased into an optimization one: An energy-like error functional is introduced. We prove that the optimality condition of the first order is equivalent to solving an interfacial equation which turns out to be a Cauchy–Steklov–Poincaré operator. Numerical trials highlight the efficiency of the present method. To cite this article: A. Ben Abda et al., C. R. Mecanique 337 (2009). 相似文献
60.
This paper is concerned with the severely ill-posed Cauchy–Stokes problem. We are interested in a data completion problem which is exploited to detect small leaks to control water loss Kim et al. (2008) [1]. This inverse problem is rephrased into an optimization one: An energy-like error functional is introduced. We prove that the optimality condition of the first order is equivalent to solving an interfacial equation which turns out to be a Cauchy-Steklov-Poincaré operator. Numerical trials highlight the efficiency of the method. 相似文献