84 research outputs found

    On the cohomology of plus/minus Selmer groups of supersingular elliptic curves in weakly ramified base fields

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    Let E/QE/\mathbb{Q} be an elliptic curve and let p5p\ge 5 be a prime of good supersingular reduction. We generalize results due to Meng Fai Lim proving Kida's formula and integrality results for characteristic elements of signed Selmer groups along the cyclotomic Zp\mathbb{Z}_p-extension of weakly ramified base fields K/QpK/\mathbb{Q}_p.Comment: 29 page

    Application of the magnetoresistive sensor for displacement measurement

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    An experimental rig was designed and successfully built to perform static and dynamic calibrations of the Philips magnetoresistive sensor. Characteristic of the sensor was also evaluated. A larger linear range can be achieved by having the sensor's transverse magnetic field pointing towards the stainless steel target. The measuring system behaves linearly with the variation of air gap from 0 to 0.46mm. The sensitivity of the measurement system is about 3 milivolts per micron of air gap variation. In terms of dynamic response, the magnetoresistive sensor performs as well as the commercially available Bently Nevada 5mm eddy curent displacement probe.Master of Science (Mechanics & Processing of Materials

    On order of vanishing of characteristic elements

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    Let pp be a fixed odd prime. Let EE be an elliptic curve defined over a number field with either good ordinary reduction or multiplicative reduction at each prime of FF above pp. We shall study the characteristic element of the Selmer group of EE over a pp-adic Lie extension. In particular, we relate the order of vanishing of these characteristic element evaluated at Artin representations to the Selmer coranks and their twists in the intermediate subextensions of the pp-adic Lie extension.Comment: Several minor changes; added new reference

    Notes on the fine Selmer groups

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    On the structure of even KK-groups of rings of algebraic integers

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    In this paper, we describe the higher even KK-groups of the ring of integers of a number field in terms of class groups of an appropriate extension of the number field in question. This is a natural extension of the previous collective works of Browkin, Keune and Kolster, where they considered the case of K2K_2. We then revisit the Kummer's criterion of totally real fields as generalized by Greenberg and Kida. In particular, we give an algebraic KK-theoretical formulation of this criterion which we will prove using the algebraic KK-theoretical results developed here.Comment: Some minor change

    On the pp-divisibility of even KK-groups of the ring of integers of a cyclotomic field

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    Let kk be a given positive odd integer and pp an odd prime. In this paper, we shall give a sufficient condition when a prime pp divides the order of the groups K2k(Z[ζm+ζm1])K_{2k}(\mathbb{Z}[\zeta_m+\zeta_m^{-1}]) and K2k(Z[ζm])K_{2k}(\mathbb{Z}[\zeta_m]), where ζm\zeta_m is a primitive mmth root of unity. When FF is a pp-extension contained in Q(ζl)\mathbb{Q}(\zeta_l) for some prime ll, we also establish a necessary and sufficient condition for the order of K2(p2)(OF)K_{2(p-2)}(\mathcal{O}_F) to be divisible by pp. This generalizes a previous result of Browkin which in turn has applications towards establishing the existence of infinitely many cyclic extensions of degree pp which are (p,p1)(p, p-1)-rational.Comment: Some minor corrections, some reogranization of the presentatio
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