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991.
What we believe to be a new arrangement of an optical vortex interferometer (OVI) is presented. In the proposed configuration the optical vortex lattice is generated in a one-wave setup by use of birefringent elements--Wollaston compensators. The obtained vortex lattice is regular and stable, which is necessary for predicted applications. The new OVI configuration allows the measurement of waves and optical media properties. 相似文献
992.
Beaconless stochastic parallel gradient descent laser beam control: numerical experiments 总被引:4,自引:0,他引:4
We apply a target-in-the-loop strategy to the case of adaptive optics beam control in the presence of strong atmospheric turbulence for air-to-ground directed energy laser applications. Using numerical simulations we show that in the absence of a cooperative beacon to probe the atmosphere it is possible to extract information suitable for effective beam control from images of the speckled and strongly turbulence degraded intensity distribution of the laser energy at the target. We use a closed-loop, single-deformable-mirror adaptive optics system driven by a target-in-the-loop stochastic parallel gradient descent optimization algorithm minimizing a mean-radius performance metric defined on the image of the laser beam intensity distribution formed at the receiver. We show that a relatively low order 25-channel zonal adaptive optical beam control system controlled in this way is capable of achieving a high degree of turbulence compensation with respect to energy concentration if the tilt can be corrected separately. 相似文献
993.
M. Czaja M. Makowski M. Szociński K. Darowicki L. Chmurzyński 《International Journal of Thermophysics》2007,28(3):865-875
The acidity constants of molecular acid, K
a
(HA), cationic acid, K
a
(BH+), as well as the equilibrium constants of anionic homoconjugation, , cationic homoconjugation, , and molecular heteroconjugation, KAHB, have been determined in (n-butylamine + acetic acid) systems without proton transfer in binary [dimethyl sulfoxide (DMSO) + 1,4-dioxane (D)] solvent
mixtures. The constants were determined by using the potentiometric titration method at a fixed ionic strength. It is concluded
that the molecular heteroconjugation constants in the mixed solvent systems studied are linearly related to the 1,4-dioxane
content. Furthermore, in the (acid + base) systems without proton transfer, the direction of titration (direct B + HA or reverse
HA + B) has been found to affect the precision of determination of reliable values of molecular heteroconjugation constants.
Moreover, it has been found that the relative dielectric constants of the solvent mixtures studied change linearly as a function
of solvent composition, as well as solvent components do not show interactions of solvent–solvent type. 相似文献
994.
Aaron Gilbert Alireza Tourani-Rad Tomasz Piotr Wisniewski 《Management International Review》2007,47(5):745-766
Abstract and Key Results
相似文献
• | Despite the importance of insider trading laws in promoting a strong financial market, the impact of regulations in minimizing the detrimental effects of insider trading is unsettled. |
• | We add to the literature by examining the impact of the introduction of the Securities Market Amendment Act 2002 in New Zealand on several aspects of the market, namely bid-ask spreads, liquidity, price volatility and the cost of capital. |
• | We find strong evidence of predicted reductions in the cost of capital, bid-ask spreads and volatility accompanied by increases in liquidity. We conclude that the change in regulations has had a positive impact on the market. |
995.
RAPD with microsatellite as a tool for differentiation of Candida genus yeasts isolated in brewing 总被引:3,自引:0,他引:3
Walczak E Czaplińska A Barszczewski W Wilgosz M Wojtatowicz M Robak M 《Food microbiology》2007,24(3):305-312
Fifteen wild yeast strains were isolated in two factories of a lager brewing company in Poland. Their identification with API 32C system showed mainly the presence of Candida sake species (7/15). To differentiate the isolates, randomly amplified polymorphic DNA (RAPD) with (GTG)(5), (GAC)(5), (GACA)(4) microsatellite primers and M13 core sequence (5'-GAG GGT GGC GGT TCT-3') were chosen. The results of patterns similarity are presented as dendrograms for each RAPD analysis and for overall patterns. On the overall patterns, all isolates identified as C. sake, except Strain No. 1, were regrouped in one cluster. Collection strain C. sake CBS 617 was similar in 46% to the cluster with six isolates (Strain Nos. 3, 6, 8, 11, 13, 14). The second reference strain C. sake CBS 159 and the Strain No. 1 were regrouped with other Candida species (collection strains) showing, respectively, only 20% and 42% of similarity to other C. sake strains. The similarity based on the overall dendrogram between isolate Nos. 3, 6, 8, 11, 13, 14 and C. sake CBS 617 was 49%. Between those strains and other Candida, the similarity was only 37%. 相似文献
996.
Foetal fibroblasts introduced to cleaving mouse embryos contribute to full-term development 总被引:1,自引:0,他引:1
Piliszek A Modliński JA Pyśniak K Karasiewicz J 《Reproduction (Cambridge, England)》2007,133(1):207-218
Foetal fibroblasts (FFs) labelled with vital fluorescent dye were microsurgically introduced into eight-cell mouse embryos, three cells to each embryo. FFs were first identified in the inner cell mass (ICM) in about one-third of embryos, whereas in three quarters of embryos FFs were located among trophoblast cells. Some elimination of FFs from trophoblast occurred later on. Eventually, in blastocysts' outgrowths, an equally high contribution from FFs progeny (60%) was found in both ICM and trophoblast. Three days after manipulation, FFs resumed proliferation in vitro. More than three FFs were found in 46.2% of embryos on day 4. On the 7th day in vitro in 70% of embryos more than 12 FFs were found, proving at least three cell divisions. To study postimplantation development, the embryos with FFs were transferred to pseudopregnant recipients a day after manipulation. After implantation, FFs were identified by electrophoresis for isozymes of glucose phosphate isomerase (GPI). A single 11-day embryo delayed to day 8 proved chimeric by expressing both donor isozyme GPI-1B and recipient GPI-1A. Similar chimerism was found in the extraembryonic lineage of 11% of embryos by day 12. Starting from day 11 onwards, in 32% of normal embryos and in 57% of foetal membranes, hybrid GPI-1AB isozyme, as well as recipient isozyme, was present. Hybrid GPI-1AB can only be produced in hybrid cells derived by cell fusion, therefore, we suggest that during postimplantation development, FFs are rescued by fusion with recipient cells. In the mice born, hybrid isozyme was found in several tissues, including brain, lung, gut and kidney. We conclude that somatic cells (FFs) can proliferate in early embryonic environment until early postimplantation stages. Foetuses and the mice born are chimeras between recipient cells and hybrid cells with contributions from the donor FFs. Transdifferentiation as opposed to reprogramming by cell fusion can be considered as underlying cellular processes in these chimeras. 相似文献
997.
Piotr Dobrzynski 《Polymer》2007,48(8):2263-2279
The paper presents the mechanism of the polymerization of ?-caprolactone with the use of Zr(Acac)4. At the first stage of the initiation of the polymerization, a reaction consisting of proton transfer from caprolactone to acetylacetonate ligand and then ligand exchange reaction with release of free acetylacetone (HAcac) occur. Complex 1, arisen as a product of this reaction, is the actual initiator of the observed polymerization. During the conducted polymerization the molar mass increase is directly proportional to monomer conversion degree. On the basis of observed phenomenon, the polymerization of cyclic trimethylene carbonate (TMC) applying ?-caprolactone as a co-initiator is possible. Complex 1 arose in the initial phase of this reaction as well, being an equally efficient initiator for TMC polymerization. Using Zr(Acac)4 as an initiator for an ?-caprolactone/TMC copolymerization resulted in obtaining a series of copolymers with varied, predicted composition and high molar mass values. 相似文献
998.
999.
Lemek T Mazurkiewicz J Stobinski L Lin HM Tomasik P 《Journal of nanoscience and nanotechnology》2007,7(9):3081-3088
Several aromatic compounds derived from benzene by its annelation (naphthalene, anthracene, phenanthrene, pyrene) and exocyclic substitution (e.g., nitrobenzene, dinitrobenzenes, trinitrobenzene, chlorobenzene, N,N-dimethylaniline, and others) and endocyclic substitution (pyridine, quinoline, isoquinoline) efficiently sorbed on multi-walled carbon nanotubes (MWCNTs). Equilibrium constants for the sorption process have been determined. Computations of the energy of formation were performed for surface complexes of those arenes on single-walled carbon nanotubes (SWCNTs). Formation energies of those complexes were correlated against the experimental equilibrium constants. The latter were also correlated against calculated LUMO energy of the arenes. Solely, limited tendencies to the linearity could be observed. The analysis of the results of the correlations indicated that the arenes acting as the charge acceptors formed stronger complexes than arenes with a high electron density in the molecular orbital, for instance, N, N-dimethylaniline. The area of the arene--SWCNT contact was very essential for the complexation. The proximity of the HOMO orbital of SWCNT and LUMO of the arene was another essential factor. Bulky substituents in the arene molecules obscured their efficient contact with SWCNT. 相似文献
1000.
Hashimoto M Garstecki P Whitesides GM 《Small (Weinheim an der Bergstrasse, Germany)》2007,3(10):1792-1802
A method is described for the formation of stable, composite aqueous emulsions of 1) combinations of distinct families of bubbles of nitrogen, 2) combinations of distinct families of droplets of an organic fluid (either perfluoro(methyl)decalin or hexadecane), and 3) combinations of bubbles and droplets. A system of two or three microfluidic flow-focusing units is coupled to a single outlet channel. The composite emulsions can be precisely tuned, both in their composition and in the number fraction of components--either bubbles or droplets--of different types. The use of microfluidic technology, with closely coupled flow-focusing units, guarantees that the emulsions are mixed locally at a controlled local stoichiometry. The emulsions self-assemble in a nonequilibrium process to form a wide variety of highly organized periodic lattices. 相似文献