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Eric Bach Richard Lukes Jeffrey Shallit H. C. Williams. 《Mathematics of Computation》1996,65(216):1737-1747
Let be a positive integer. We say looks like a power of 2 modulo a prime if there exists an integer such that . First, we provide a simple proof of the fact that a positive integer which looks like a power of modulo all but finitely many primes is in fact a power of . Next, we define an -pseudopower of the base to be a positive integer that is not a power of , but looks like a power of modulo all primes . Let denote the least such . We give an unconditional upper bound on , a conditional result (on ERH) that gives a lower bound, and a heuristic argument suggesting that is about for a certain constant . We compare our heuristic model with numerical data obtained by a sieve. Some results for bases other than are also given.
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This paper describes alternative measurement and data-processing approaches that can reduce effects of experimental variables on results obtained with a membrane-based sensor for oxygen. In the new approaches, the membrane-based sensor is first equilibrated with the sample solution, after which a polarizing voltage is applied and current vs. time data are recorded as the response decays toward a steady-state condition. Current vs. time data are then processed by a fixed-time option and an integration option designed to determine the charge corresponding to the total amount of oxygen inside the membrane when a polarizing voltage is applied. The current measured at a fixed time and the total charge varied linearly with oxygen concentration between 0.05 and 0.26 mmol l(-1). Pooled relative standard deviations (N = 35) for the measurement/data-processing step were near 0.4% for the new pre-equilibrium options compared to a value of 0.3% for the steady-state option. Dependencies of the pre-equilibrium options on membrane thickness and stirring rate in the most sensitive regions were at least two orders of magnitude smaller than for the steady-state option. 相似文献
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In this paper the enhancement of the values of the cubic molecular hyperpolarizability of the nickel benzendithiol system, resulting from the selective addition of acceptor and donor groups to the ligand structure, is presented. The polarization of the molecular electronic structure is calculated by the finite field method. Significant increases in the values of are obtained from bridging two p-nitroaniline molecules with the square planar nickel structure. These results show that structures with significant values of x
(2) that are derived from the inclusion of donor and acceptor groups might also be included into the ligands of the nickel dithiolene complex to give rise to materials with enhanced values of x
(3). 相似文献