منابع مشابه
The Periods of Cataclysmic Variables
The present status of the period studies of cataclysmic variables is briefly reviewed, mainly from the observational point of view. A few comments on individual objects include EM Cyg, Z Cha, WZ Sge and AM CVn.
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We prove that all polynomials in several variables can be decomposed as the sum of kth powers: P (x1, . . . , xn) = Q1(x1, . . . , xn) + · · ·+Qs(x1, . . . , xn), provided that elements of the base field are themselves sum of kth powers. We also give bounds for the number of terms s and the degree of the Qi . We then improve these bounds in the case of two variables polynomials to get a decompo...
متن کاملWaring’s Problem for Polynomials in Two Variables
We prove that all polynomials in several variables can be decomposed as the sums of kth powers: P (x1, . . . , xn) = Q1(x1, . . . , xn) + · · ·+Qs(x1, . . . , xn), provided that elements of the base field are themselves sums of kth powers. We also give bounds for the number of terms s and the degree of the Qi . We then improve these bounds in the case of two variables polynomials of large degre...
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Continuing our work from Paper I (Southworth et al., 2006) we present mediumresolution spectroscopy and broad-band photometry of seven cataclysmic variables (CVs) discovered by the Sloan Digital Sky Survey. For six of these objects we derive accurate orbital periods, all which are measured for the first time. For SDSS J013132.39−090122.2, which contains a non-radially pulsating white dwarf, we ...
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The performance of a decision making unit (DMU) can be evaluated in either across-sectional or a time-series manner, and data envelopment analysis (DEA) is a useful method for both types of evaluation. The Malmquist productivity index (MPI) evaluates the change in efficiency of a DMU between two time periods. It is defined as the product of the Catch-up and Frontier-shift terms. In this pape...
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 1973
ISSN: 0035-8711,1365-2966
DOI: 10.1093/mnras/162.1.91