31,746 research outputs found

    The average rank of elliptic curves

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    Zeros of Systems of p{\mathfrak p}-adic Quadratic Forms

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    It is shown that a system of rr quadratic forms over a p{\mathfrak p}-adic field has a non-trivial common zero as soon as the number of variables exceeds 4r4r, providing that the residue class field has cardinality at least (2r)r(2r)^r.Comment: Revised version, with better treatment and results for characteristic

    The largest prime factor of X3+2X^3+2

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    The largest prime factor of X3+2X^3+2 has been investigated by Hooley, who gave a conditional proof that it is infinitely often at least as large as X1+δX^{1+\delta}, with a certain positive constant δ\delta. It is trivial to obtain such a result with δ=0\delta=0. One may think of Hooley's result as an approximation to the conjecture that X3+2X^3+2 is infinitely often prime. The condition required by Hooley, his R^{*} conjecture, gives a non-trivial bound for short Ramanujan-Kloosterman sums. The present paper gives an unconditional proof that the largest prime factor of X3+2X^3+2 is infinitely often at least as large as X1+δX^{1+\delta}, though with a much smaller constant than that obtained by Hooley. In order to do this we prove a non-trivial bound for short Ramanujan-Kloosterman sums with smooth modulus. It is also necessary to modify the Chebychev method, as used by Hooley, so as to ensure that the sums that occur do indeed have a sufficiently smooth modulus

    Recent advances in satellite observations of solar variability and global atmospheric ozone

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    The launch of Nimbus 4 in April 1974 has made possible simultaneous measurements of the ultraviolet solar irradiance and the global distribution of atmospheric ozone by the monitor of ultraviolet solar energy (MUSE) and backscatter ultraviolet (BUV) experiments respectively. Two long lived ultraviolet active solar regions which are about 180 deg apart in solar longitude were observed to be associated with central meridian passages of solar magnetic sector boundaries. The boundaries may be significant in the evaluation of correlations between solar magnetic sector structure and atmospheric circulation
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