Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Study of Pc4-5 Geomagnetic Pulsations in the Brazilian Sector   This paper presents a study of Pc4-5 geomagnetic pulsations illustrated by
those which were observed after the sudden commencement of May 02 of 2010 at 09
: 08 UT at the Brazilian stations TTB, VSS and SMS. We carry out the spectral
analysis of a bivariate data using the Morse wavelets and calculate
polarization attributes (ellipticity ratio, tilt angle and phase difference) in
the time-frequency domain. The main pulsation wave packets occurred, for the
selected day, around noon and a small enhancement of the pulsation amplitude is
observed in the TTB station. A change in the pulsation polarization has been
found for the TTB station, which we have attributed to effects of the
equatorial electrojet.

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The categories of this paper are: q-fin
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The categories of this paper are: math-ph
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The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
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The categories of this paper are: alg-geom
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The categories of this paper are: ao-sci
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ex
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The categories of this paper are: mtrl-th
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-ex