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991.
992.
We study the vortex glass transition in disordered high temperature superconductors using Monte Carlo simulations. We use a random pinning model with strong point-correlated quenched disorder, a net applied magnetic field, long-range vortex interactions, and periodic boundary conditions. From a finite size scaling study of the helicity modulus, the rms current, and the resistivity, we obtain critical exponents at the phase transition. The new exponents differ substantially from those of the gauge glass model, but are close to those of the pure three-dimensional XY model. 相似文献
993.
Removable singularities for Hardy spaces Hp() = {f Hol(): |f|p u in for some harmonic u}, 0 < p < are studied. A setE = is a weakly removable singularity for Hp(\E) if Hp(\E) Hol(), and a strongly removable singularity for Hp(\E) if Hp(\E)= Hp(). The two types of singularities coincide for compactE, and weak removability is independent of the domain . The paper looks at differences between weak and strong removability,the domain dependence of strong removability, and when removabilityis preserved under unions. In particular, a domain and a setE that is weakly removable for all Hp, but not strongly removablefor any Hp(\E), 0 < p < , are found. It is easy to show that if E is weakly removable for Hp(\E)and q > p, then E is also weakly removable for Hq(\E). Itis shown that the corresponding implication for strong removabilityholds if and only if q/p is an integer. Finally, the theory of Hardy space capacities is extended, anda comparison is made with the similar situation for weightedBergman spaces. 相似文献
994.
Mats Anders Olofsson 《Proceedings of the American Mathematical Society》2001,129(2):515-524
We prove that every non quasi-analytic Carleman class contains functions whose graph supports measures that are absolutely continuous with respect to arc length measure and yet they have independent convolution powers in the measure algebra . The proof relies on conditions which ensure that the canonical map between two Cantor sets can be extended to a function in an arbitrary prescribed non quasi-analytic Carleman class.
995.
Philippe Grangier Anders Karlsson John Rarity 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(1):3
The collective phenomena of quantum interference, including wave particle duality and apparent non-locality, have intrigued the physics community for many years. It is only recently that we have begun to turn these somewhat counter intuitive quantum phenomena to good use. A leading force in that direction is quantum cryptography - absolute secure key exchange encoding data on the polarisation or phase of individual photons, or using the quantum correlations between pairs of particles. Technologies are now implemented to bring the various forms of quantum cryptography to commercial application. At the same time the possibility of communications applications has stimulated the study of a variety of novel quantum interference phenomena. Quantum information experiments involving two, three and four photons are planned and a novel Field of continuous variable (many photon) quantum information has emerged. These various aspects of quantum cryptography are considered in the conference “QUICK: Quan- tum interference and cryptographic keys: novel physics and advancing technologies", taking place in Cargese from April 7 to 13, 2001. Following that conference, we invite submission of original papers to a special issue of the European Physical Journal D, on the following topics: - quantum cryptography technologies, - quantum cryptography systems, - free space quantum cryptography and satellites, - pair-photon sources and multiphoton interference, - single photon sources, - continuous variable quantum information, - security aspects, - cryptographic protocols, - entanglement purification in cryptographic schemes, - novel physics and quantum gates for photonic qubits. The submitted articles should be sent to the EPJ D Editorial Office in Orsay. The deadline is July 15, 2001. We look forward to a stimulating special issue. 相似文献
996.
Wasse JC Howard CA Thompson H Skipper NT Delaplane RG Wannberg A 《The Journal of chemical physics》2004,121(2):996-1004
The microscopic structures of calcium-ammonia solutions have been established by using neutron diffraction. Total structure factors measured at 230 K reveal immediately the evolution of an uncommonly intense diffraction prepeak in the metallic solutions. As concentration is increased from 4 mole percent metal to 10 mole percent metal (i.e., saturation), this feature intensifies and shifts from 0.6 to 0.9 A(-1). It is therefore evidence of well developed intermediate-range ordering among the solvated cations, and is a microstructural signature of the observed strong phase separation of metallic (concentrated) and nonmetallic (dilute) solutions. The technique of isotopic labelling of *N by 15N was then used in conjunction with difference analysis to focus on the solvent structure in metallic solutions at 4 and 10 mole percent metal. These nitrogen-centered functions are analyzed in conjunction with classical Monte Carlo computer simulation techniques, to provide us with detailed insight into the calcium solvation and the extent of hydrogen bonding. We find that calcium is solvated by approximately 6-7 ammonia molecules, with a Ca-N distance of around 2.45 A. There is evidence of hydrogen bonding among the solvent molecules, even in the saturated 10 mole percent metal solution. 相似文献
997.
Holm A Solbu K Molander P Lundanes E Greibrokk T 《Analytical and bioanalytical chemistry》2004,378(7):1762-1768
A rapid and sensitive method for the determination of the phthalate monoesters monoethyl phthalate (MEP), monobutyl phthalate (MBP), monobenzyl phthalate (MBzP) and monoethylhexyl phthalate (MEHP), in human urine, using packed capillary column liquid chromatography coupled to electrospray quadrupole-ion trap mass spectrometry (ESI-QITMSn) has been developed. Sample volumes of 200 L of deconjugated and diluted urine were loaded onto a precolumn of 30 mm×0.32 mm I.D. packed with Hypercarb 5 m particles, using a sample carrier consisting of acetonitrile/water (15/85, v/v, adjusted to pH 2 using HCl) with a flow rate of 20 L/min. Backflushed elution onto a 100 mm×0.32 mm I.D. analytical column packed with 5 m Hypercarb particles was conducted using a tetrahydrofuran/water gradient where both solvents contained 10 mM ammonium acetate, at a flow rate of 4 L/min. Determination of the monophthalates was achieved within 8 min. Ionization was performed in the negative mode and the analytes were observed as [M-H]– at m/z=193.1, 221.1, 255.1 and 277.0 for MEP, MBP, MBzP and MEHP, respectively. Quantification was performed in the multiple reaction monitoring (MRM) mode monitoring the fragments at m/z=121.1, 177.0, 183.0 and 233.0 for MEP, MBP, MBzP and MEHP, respectively. The method was validated over the concentration range 2.5–125 ng/mL in pretreated urine samples, corresponding to 25–1250 ng/mL untreated urine, yielding correlation coefficients in the range 0.996–0.999. The within-assay (n=6) and between-assay (n=6) repeatabilities were in the range 4.0–18% and 4.8–15% RSD, respectively. The mass limits of detection were in the range 32–70 pg, corresponding to concentration limits of detection of 1.6–3.5 ng/mL of untreated urine. 相似文献
998.
Hjelm J Constable EC Figgemeier E Hagfeldt A Handel R Housecroft CE Mukhtar E Schofield E 《Chemical communications (Cambridge, England)》2002,(3):284-285
A new rod-like coordination polymer consisting of (Ru-(terpy)2) motifs bridged by bithiophene units has been prepared by electrochemical polymerisation in acidic organic medium. 相似文献
999.
Middleton DA Peng X Saunders D Shankland K David WI Markvardsen AJ 《Chemical communications (Cambridge, England)》2002,(17):1976-1977
Solid-state NMR is used to dramatically improve the efficiency and reliability of molecular crystal structure determination from X-ray powder diffraction data. 相似文献
1000.