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41.
M. Guillot A. Marchand F. Tchéou P. Feldmann H. Le Gall 《Zeitschrift für Physik B Condensed Matter》1981,44(1-2):41-52
The magnetic properties of single crystals of erbium iron garnet (ErIG) were studied in applied fields up to 150kOe between 1.4 and 300K. At low temperature, the macroscopic easy direction of the bulk magnetization is [100]; below the compensation temperature (80±2K), the magnetization presents non-linear field evolution. On the assumption of an isolated ground doublet, the anisotropy constantsK
i
(i=1,2) of ErIG are given byK
i
(Er)+K
i
(YIG); theK
i
are calculated as a function of theG andg tensor components. It is worthwhile noting that theK
i
(Er) are strongly temperature dependent; so at low temperature the anisotropy of the garnet is determined by the rare earth ions, while in the 50 K regionK
1(Er) becomes comparable toK
1(YIG) with the opposite sign which results in a very weak anisotropy of the garnet. Above 50 K,K
1(YIG) is predominant and the Fe3+ ions determine the garnet anisotropy. 相似文献
42.
43.
We derive microscopically precise identities for the geometry of small clusters in the equilibrium states of the two-dimensional Ising model with emphasis on near-critical phenomena. 相似文献
44.
Simon G. Bott Alan P. Marchand Sulejman Alihodzic Kaipenchy A. Kumar 《Journal of chemical crystallography》1998,28(4):251-258
The crystal structures of three compounds formed via ultimate nucleophilic attack of unsaturated hydrocarbon fragments are reported. Geometries of the bis(vinyl)-, mono(vinyl), and bis(ethynyl)-substituted PCU species are unexceptional. The crystal structures are dictated by the availability of intermolecular hydrogen bonding. 相似文献
45.
Sebastián Ceria Cécile Cordier Hugues Marchand Laurence A. Wolsey 《Mathematical Programming》1998,81(2):201-214
We investigate the use of cutting planes for integer programs with general integer variables. We show how cutting planes arising from knapsack inequalities can be generated and lifted as in the case of 0–1 variables. We also explore the use of Gomory's mixed-integer cuts. We address both theoretical and computational issues and show how to embed these cutting planes in a branch-and-bound framework. We compare results obtained by using our cut generation routines in two existing systems with a commercially available branch-and-bound code on a range of test problems arising from practical applications. © 1998 The Mathematical Programming Society, Inc. Published by Elsevier Science B.V.Corresponding author.This research was partly performed when the author was affiliated with CORE, Université Catholique de Louvain. 相似文献
46.
47.
48.
Rodney W. Benoist Jean-Paul Marchand Wolfgang Yourgrau 《Foundations of Physics》1977,7(11-12):827-833
We analyze the quantum mechanical measuring process from the standpoint of information theory. Statistical inference is used in order to define the most likely state of the measured system that is compatible with the readings of the measuring instrument and the a priori information about the correlations between the system and the instrument. This approach has the advantage that no reference to the time evolution of the combined system need be made. It must, however, be emphasized that the result is to be interpreted as the statistically inferred state of the original system rather than the state of the system after measurement. The phenomenon of “reduction of states” appears in this light as a consequence of incomplete information rather than the physical interaction between measured system and measuring instrument. 相似文献
49.
Courtney?L.?Sherman Jennifer?S.?BrodbeltEmail author Alan?P.?Marchand Bhaskar?Poola 《Journal of the American Society for Mass Spectrometry》2005,16(7):1162-1171
The self-assembly of ligand-metal-ligand sandwich complexes involving a novel quinoxaline-containing crown ether, 1, was studied by electrospray ionization mass spectrometry (ESI-MS). Donor-acceptor π-stacking interactions between the electron-poor
quinoxaline group of 1 and electron-rich benzene groups from benzo- or dibenzo-18-crown-6 were found to significantly enhance the formation of mixed-ligand
sandwich complexes with a free energy gain of up to 17 kJ/mol relative to sandwich formation involving macrocycles without
such aromatic functionalities. The relative intensities of the sandwich complexes were greatest with the alkali metals Na+, K+, and Rb+ as well as with the ammonium ion in equimolar concentrations with the macrocycles. The preferential formation of the mixed-ligand
sandwich complexes demonstrated that donor-acceptor π-stacking interactions contribute to the assembly of molecular structures
and can be monitored by ESI-MS. 相似文献
50.
Antignac JP Marchand P Gade C Matayron G Qannari el M Le Bizec B Andre F 《Analytical and bioanalytical chemistry》2006,384(1):271-279
Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) are widely recognized by the scientific community as persistent organic
pollutants due to their toxicity and adverse effects on wildlife and human health. The actual regulation dedicated to the
monitoring of dioxins in food is based on the measurement of 17 congener concentrations. The final result is reported as a
toxic equivalent value that takes into account the relative toxicity of each congener. This procedure can minimize the qualitative
information available from the abundances of each PCDD/PCDF congener: the characteristic contamination profile of the sample.
Multivariate statistical techniques, such as principal component analysis (PCA) or linear discriminant analysis (LDA), represent
an interesting way to investigate this qualitative information. Nevertheless, they have only been applied to the analysis
of contamination data from food products and biological matrices infrequently. The objective of the present study was to analyze
a large data set from dioxin analyses performed on various food products of animal origin. The results demonstrate the existence
of differences in congener-specific patterns between the analyzed samples. Variability was first demonstrated in terms of
the food type (fish, meat, milk, fatty products). Then a variability was observed that was related to the specific animal
species for meat and milk samples (bovine, ovine, porcine, caprine and poultry). Some practical applications of these results
are discussed. The origin(s) of the observed differences, as well as their significance, now remain to be investigated, both
in terms of environmental factors and transfer through living organisms. A better knowledge of the relation between a contamination
profile and its specific source and/or food product should be of great interest to scientists working in the fields of contaminant
analysis, toxicology and metabolism, as well as to regulatory bodies and risk assessors in charge of final decisions regarding
the eventual hazards associated with theses substances. 相似文献