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61.
We develop measure theory in the context of subsystems of second order arithmetic with restricted induction. We introduce a combinatorial principleWWKL (weak-weak König's lemma) and prove that it is strictly weaker thanWKL (weak König's lemma). We show thatWWKL is equivalent to a formal version of the statement that Lebesgue measure is countably additive on open sets. We also show thatWWKL is equivalent to a formal version of the statement that any Borel measure on a compact metric space is countably additive on open sets.The research of both authors was partially supported by NSF Grant DMS-8701481. 相似文献
62.
63.
Samit Mandal J Gerl H Geissel K Hauschild M Hellström Z Janas I Kojouharov Y Kopatch RC Lemmon P Mayet Z Podolyak PH Regan H Schaffner C Schlegel J Simpson HJ Wollersheim 《Pramana》2001,57(1):161-164
Feasibility of gamma-ray spectroscopy at relativistic energies with exotic heavy-ions and new generation of germanium detectors
(segmented Clover) is discussed. An experiment with such detector array and radioactive is discussed. 相似文献
64.
The construction and evaluation of a gamma-ray detector for capillary zone electrophoresis is described. The detector was shown to have a linear response from the limit of detection 10 to 500 Bqcm-3 corresponding to 5.1 x 10(-17) to 2.55 x 10(-15) gcm-3 43Tc99m. The application of the detector for the analysis of some radiopharmaceuticals is presented. 相似文献
65.
Wai Kuan Foong Angus R. Simpson Holger R. Maier Stephen Stolp 《Annals of Operations Research》2008,159(1):433-450
A number of algorithms have been developed for the optimization of power plant maintenance schedules. However, the true test
of such algorithms occurs when they are applied to real systems. In this paper, the application of an Ant Colony Optimization
formulation to a hydropower system is presented. The formulation is found to be effective in handling various constraints
commonly encountered in practice. Overall, the results obtained using the ACO formulation are better than those given by traditional
methods using engineering judgment, which indicates the potential of ACO in solving realistic power plant maintenance scheduling
problems. 相似文献
66.
Camilla Nilsson Neil Simpson Michael Malkoch Mats Johansson Eva Malmström 《Journal of polymer science. Part A, Polymer chemistry》2008,46(4):1339-1348
Well‐defined, allyl‐ether functional, first‐generation dendrimers have been synthesized. The convergent growth approach was utilized, using the anhydride of the allyl‐ether terminated building block. Three different core moieties were used: trimethylolpropane, trisphenol, and ditrimethylolpropane. The coupling reactions proceeded in good yields and all compounds were characterized by NMR, MALDI‐TOF, and SEC. The allyl‐terminated dendrimers were crosslinked by thiol–ene chemistry, using a multifunctional thiol, TriThiol, to give clear and smooth films. The photopolymerization was conducted in the presence of a photoinitiator, Irgacure 651, and no traces of either allyl‐ether groups or thiols were observed by FT‐Raman after cure. All crosslinked films were characterized with respect to mechanical (DMA) and thermal (DSC) properties. It was found that homogeneous networks were formed and that the core functionality and structure had little effect on the network properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1339–1348, 2008 相似文献
67.
We have investigated the smectic E-smectic B transition with the aid of a model smectogen whose properties have been calculated using the Monte Carlo technique of computer simulation. The lath-like mesogenic molecules are defined to lie in a plane with their centres on a triangular lattice and with their long axes orthogonal to the smectic layer. The quadrupolar interaction, restricted to nearest neighbours, is assumed to be responsible for the herring-bone arrangement of the molecular short axes, characteristic of the smectic E phase. The computer simulations have been employed to evaluate both thermodynamic and structural parameters as a function of temperature. The model smectogen is found to exhibit a continuous transition at which the long range herring-bone structure of the smectic E phase is destroyed only to be replaced by the analogous short range structure of the smectic B. Where possible the results simulated for the model smectogen are compared with the behaviour of real mesogens and the predictions of molecular field theories for the transition. In particular, contact is made with X-ray diffraction studies of the two phases by using optical techniques to generate the diffraction patterns associated with configurations produced by the simulation. The model is found to be in good accord with experiment but the molecular field prediction of the smectic E-smectic B transition temperature is shown to be poor. 相似文献
68.
Richard Ducray Pascal Boutron Hervé Germain Maryannick Lamorlette Mickael Maudet Georges Pasquet Iain Simpson 《Tetrahedron letters》2010,51(36):4755-4701
A two-step synthesis of 3-(2-chloropyrimidin-4-yl)imidazo[1,2-a]pyridines is presented. The late stage elaboration of the imidazopyridine through a cyclocondensation allows a rapid access to a variety of substitution patterns. The intermediate enol ethers were obtained from inexpensive reagents in a ligand-free Heck coupling. This methodology has been extended to the formation of pyrazolo[1,5-a]pyridines via a formal 1,3-dipolar cycloaddition. 相似文献
69.
Bucaro JA Kraus L Houston BH Simpson H Sarkissian A 《The Journal of the Acoustical Society of America》2011,129(6):3453-3456
A 48 m rail with a moving receiver was used to measure forward scattering from a spherical shell lying on the bottom in the Gulf of Mexico. The target was mid-way between the source and rail, on a line from the source bisecting the rail. The major obstacle to the measurement of forward scattering is the much stronger source signal which overlaps the scattered signal in space and time. Here, forward scattered target strength is obtained by processing the received signals using a wavenumber filter to remove the incident wave. The result compares favorably to that obtained from numerical predictions. 相似文献
70.
Bun Chan Elicia Wong Leh See Jim Simpson Eng Wui Tan 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):e354-e355
The stereochemistries at positions 2 and 3 of the title compounds, C15H21BrClNO, (I), and C15H12BrClN2O3, (II), have been confirmed by X‐ray structural analysis. The halogen atoms adopt an antiperiplanar arrangement in each case. 相似文献