Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Investigating population dynamics of the Kumbh Mela through the lens of
  cell phone data   The Kumbh is a religious Hindu festival that has been celebrated for
centuries. The 2013 Kumbh Mela, a grander form of the annual Kumbh, was
purportedly the largest gathering of people in human history. Many of the
participants carried cell phones, making it possible for us to use a
data-driven approach to document this magnificent festival. We used Call Detail
Records (CDRs) from participants attending the event, a total of 390 million
records, to investigate its population dynamics. We report here on some of our
preliminary findings.

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The categories of this paper are: nlin
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The categories of this paper are: math
33
The categories of this paper are: plasm-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: q-fin
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The categories of this paper are: supr-con
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The categories of this paper are: solv-int
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The categories of this paper are: cmp-lg
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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: cond-mat
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The categories of this paper are: dg-ga
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The categories of this paper are: gr-qc
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The categories of this paper are: chao-dyn
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ex