Showing papers by "École Polytechnique Fédérale de Lausanne published in 1979"
TL;DR: An exact method is given which performs better than the Randall-Brown algorithm and is able to color larger graphs and the new heuristic methods, the classical methods, and the exact method are compared.
Abstract: This paper describes efficient new heuristic methods to color the vertices of a graph which rely upon the comparison of the degrees and structure of a graph. A method is developed which is exact for bipartite graphs and is an important part of heuristic procedures to find maximal cliques in general graphs. Finally an exact method is given which performs better than the Randall-Brown algorithm and is able to color larger graphs, and the new heuristic methods, the classical methods, and the exact method are compared.
1,510 citations
TL;DR: A comparison of CBI for rat-liver DNA with hepatocarcinogenic potency reveals a surprisingly good quantitative correlation and refineements for a DNA-binding assay are proposed.
Abstract: The covalent binding of chemical carcinogens to DNA of mammalian organs is expressed per unit dose, and a 'Covalent-Binding Index', CBI, is defined. CBI for various carcinogens span over 6 orders of magnitude. A similar range is observed for the carcinogenic potency in long-term bioassays on carcinogenicity. For the assessment of a risk from exposure to a carcinogen, the total DNA dmaage can be estimated if the actual dose is also accounted for. A detailed description is given for planning and performing a DNA-binding assay. A complete literature survey on DNA binding in vivo (83 compounds) is given with a calculation of CBI, where possible, 153 compounds are listed where a covalent binding to any biological macromolecule has been shown in vivo or in vitro. Recent, so far unpublished findings with aflatoxin M1, macromolecule-bound aflatoxin B1, diethylstilbestrol, and 1,2-epithiobutyronitrile are included. A comparison of CBI for rat-liver DNA with hepatocarcinogenic potency reveals a surprisingly good quantitative correlation. Refinements for a DNA-binding assay are proposed. Possibilites and limitations in the use of DNA binding in chemical carcinogenesis are discussed extensively.
408 citations
TL;DR: In this article, the angular distribution of light emitted by an atomic system, e.g., a fluorescent molecule, located in a dielectric medium 1 at distance z 0 from the interface to a different dielectrous medium 2, was derived.
Abstract: We have derived analytic expressions for the angular distribution of light emitted by an atomic system, e.g., a fluorescent molecule, located in a dielectric medium 1 at distance z0 from the interface to a different dielectric medium 2. The theory is rigorously valid for electric and magnetic dipole transitions with arbitrary orientation of the dipole transition moment. (In Paper II [ J. Opt. Soc. Am.57, 1615– 1619 ( 1977)], only the special case of dipoles oriented perpendicular to the interface had been treated.) The radiation patterns of dipoles located on the interface (z0 = 0) and oriented parallel to it, and ensembles of such dipoles radiating incoherently with randomly oriented dipole moments were examined in particular. They differ greatly from the corresponding well-known dipole radiation patterns in an unbounded medium 1, due to the wide-angle interferences of emitted plane waves, and radiation from evanescent waves in the dipole’s near field into medium 2, if this is denser than medium 1.
279 citations
TL;DR: In this paper, a direct numerical treatment for arbitrary one-and two-dimensional internal motions of an arbitrary non-linear molecule is presented for comparison with observed intramolecular motion spectra and shifts of rotational constants associated with excitation of such motions.
261 citations
TL;DR: In this article, the relevance of the statistical distribution of the quencher amongst the micelles with respect to the interpretation of fluorescence quenching experiments is discussed and several mechanisms are analyzed.
237 citations
TL;DR: Recent data, and concepts gradually emerging, now permit us to look at the process from a new perspective, which is synthesized here in the proposal of a mitochondrial Ca*’ cycle.
177 citations
TL;DR: In this paper, a series of PMMA samples of different molecular weights and degrees of copolymerisation have been tested for their crack-healing behavior, and a qualitative explanation of these effects, based on structural parameters, is given.
Abstract: A series of PMMA samples of different molecular weights and degrees of copolymerisation have been tested for their crack-healing behavior. Slightly above Tg, a diffusional interpenetration of chain segments takes place. The fracture toughness in the plane of the interpenetrated interface was measured in short- and longtime experiments. After very short penetration times of only 5 min, full material resistance was regained in short-time experiments, whereas the long-time properties were not restored. A qualitative explanation of these effects, based on structural parameters, is given.
151 citations
TL;DR: For a given concentration and optical depth, the absorption was found to be dependent on the imaginary part, n2, of the complex index of refraction, n = n 1 − in 2, of material used.
132 citations
TL;DR: In this paper, anelastic measurements in the low frequency range have been made on a martensitic equiatomic NiTi alloy, where an internal friction peak was observed with a corresponding sharp minimum of frequency at the same temperature.
117 citations
TL;DR: A simple device for the application of ion-selective liquid membrane electrodes to biochemistry is described, suitable for the measurement of fast changes in ion activities, since the stirring system described has a mixing time below 0.1 s.
116 citations
TL;DR: In this paper, the U Pb zircon suite method was used to date eclogitic rocks from the Munchberg Gneiss Massif (northeast Bavaria).
TL;DR: A method for the isolation of vacuoles which is based on the slicing of plasmolysed horseradish root tissue is described, and it is calculated that 100% of the glucosinolates as well as the bulk of acid phosphatase activity are present in this compartment.
TL;DR: The organ distribution of poly(methyl-2-14C-methacrylate) nanoparticles after 0.5,1,2,6, and 24 hr and after 7 days, as well as the elimination of degradation products in urine, feces, and breath, was measured for 7 days after intravenous administration to rats.
TL;DR: In this article, the optical absorption spectrum of excited ruthenium tris-bipyridyl (Ru(bpy)2+3) in the range of 244-500 nm was determined by applying the method of intensity dependence measurement.
TL;DR: In this article, a computer program for solving the general production planning problem in the case of multi-purpose batch chemical plants is presented, where the procedure starts with an evolutionary enumeration of alternative production strategies.
TL;DR: It is proposed to investigate new aspects of the induced speckle motion due to rigid-body movements of a model using as a starting point the well-known concept of homology, first stated in holographic interferometry.
Abstract: In line with the current interest in speckle motion in free-space propagation, it is proposed to investigate new aspects of the induced speckle motion due to rigid-body movements of a model using as a starting point the well-known concept of homology, first stated in holographic interferometry, the importance of which has only recently been realized in speckle metrology. At the outset, stating the homology conditions leads to a general expression relating the speckle shift to the geometrical parameters at the recording and to the six degrees of movement of the object surface. The expression presented in this explicit form is found to be true for both opaque and thin transparent diffusing models and for different conditions of illumination and observation. The study is then extended to (1) when the object is at rest, subjecting the illuminating source to a small displacement and (2) when the wavelength of the illuminating beam is changed between the two exposures. The case of the rigid-body displacement of the object is experimentally verified and the results are found to be in good agreement with theory. The viability of the method to make measurements is assessed, several applications are envisaged, and some advantages are pointed out.
TL;DR: This first set of data clearly demonstrates that the study of maternal effects in Drosophila is an efficient tool to analyse the in vivo function of repair mutations on chemically induced mutagenesis.
Abstract: Drosophila melanogaster males from a Basc stock were mutagenized with either X-rays, ethyl methanesulfonate (EMS), or nitrogen mustard (HN2). Groups of identically treated males were crossed to different types of female. Sex-linked recessive lethals were scored as a genetic end point. The females used were homozygous for X-chromosomal mutations (mus(1)101D1, mus(1)104D1, mei-9 or mei-41D5) which lead to defective DNA repair and which increase the mutagen sensitivity of larvae. Females from a white stock with normal DNA repair capacities served as controls. The premutational lesions induced in mature sperm are only processed after insemination by the maternal enzyme systems present in the oocytes. Differences in the efficiency of the processing of lesions can lead to maternal effects on the frequency of mutations recovered from mutagenized sperm. It was found that, with the exception of mus(1)104D1, all mutants analysed significantly modify the mutation fixation of one or more types of premutational lesions. The most drastic effect is found with the mus(1)101D1 stock in which HN2-induced DNA cross-links do not lead to sex-linked recessive lethals. It is assumed that mus(1)101D1 is defective in an early step of DNA cross-link repair. Our first set of data clearly demonstrates that the study of maternal effects in Drosophila is an efficient tool to analyse the in vivo function of repair mutations on chemically induced mutagenesis.
TL;DR: In this paper, a tensile rheometer for polymer melts was used to measure the elastic recovery eR(e) of a low density polyethylene melt up to total strains e=7, i.e. stretch λ=1097, at 150°C and two strain rates, e=0.03 and 0.1 s−1.
Abstract: By means of a new tensile rheometer for polymer melts, stress-strain curves σ(e) and the elastic recovery eR(e) of a low density polyethylene melt were measured up to total strains e=7, i.e. stretch λ=1097, at 150°C and two strain rates, e=0.03 and 0.1 s−1. Tensile tests up to very high strains e give relevant results only if the test performance is characterized by quality parameters which are defined and given in this paper. The test results show a maximum in a as well as in eR at about e=5.5. Hence, in the range of e investigated, a rheologically steady-state of flow does not exist.
TL;DR: A comparison of two types of ghosts showed that isotonic ghosts possess an intact calmodulin-(Ca 2+ + Mg 2+ )ATPase complex, and that theCalmodulin remained with the ATPase during solubilization and reconstitution.
TL;DR: In this article, the distribution of grain shapes in two-dimensional sections, as characterized by the topological parameter n, is approached from a probabilistic point of view, and it is predicted that the mean coordination number m n of the nearest neighbours of all n -sided grains is related to n through Weaire's relation: m n = 5 + (6 + μ 2 )/n in which μ 2 is the second central moment of the overall distribution of the grain coordination numbers.
TL;DR: In this paper, a hole was observed for the first time within the inhomogeneous absorption profile with a low power diode laser, with a width of 0.006 ± 0.002 cm -1 at temperatures -1.
TL;DR: From the studies reported on Ca*+ transport in (inverted) SMP, one conclusion has in general emerged, namely, the requirement for inorganic phosphate, which has been interpreted with an energylinked uptake of phosphate on one of the two known phosphate carriers, or on a new one.
TL;DR: In this article, the authors studied the optical pumping process in infrared multiphoton induced unimolecular reactions by measuring the pressure dependence of the reaction yield as a function of the laser energy fluence and pulse shape.
TL;DR: In this article, the influence of sputtering on surface composition of ternary Fe-Cr-Mo alloys was investigated using an Auger electron spectroscopy (AES) combined with Kr+-sputtering.
TL;DR: In this article, the amino-carbonylation of aliphatic aldehydes proceeds with exceptionally high selectivity and some aspects of the reaction mechanism are discussed which may explain the failure to obtain an asymmetric synthesis under the conditions used.
TL;DR: In this paper, the authors show that mass transfer at vertical plates with gas sparging obeys formally the same correlation as mass transfer in turbulent natural convenction due to concentration or temperature differences.
TL;DR: It is indicated that internal, but not external Ca2+ is responsible for the inhibition of adenine nucleotide translocase activity and inhibition of the exchange activity by Ca2- occurs even in conditions in which external adenines nucleotide concentrations are rate-limiting.
TL;DR: The measured energies of bulk plasmons, 18.3 ± 0.5 eV and 20.3 −0.5eV for amorphous and black phosphorus, respectively, agree reasonably with the theoretical values as discussed by the authors.
TL;DR: In this paper, the room temperature structures of CH 3 NH 3 ) 2 CdBr 4 and Cs 2 DBr 4 were determined and two compounds with tetrahedral coordination were shown to have monoclinic and orthorhombic properties.