Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Temperature Dependent Heterogeneous Rotational Correlation in Lipids   Lipid structures exhibit complex and highly dynamic lateral structure; and
changes in lipid density and fluidity are believed to play an essential role in
membrane targeting and function. The dynamic structure of liquids on the
molecular scale can exhibit complex transient density fluctuations. Here the
lateral heterogeneity of lipid dynamics is explored in free standing lipid
monolayers. As the temperature is lowered the probes exhibit increasingly broad
and heterogeneous rotational correlation. This increase in heterogeneity
appears to exhibit a critical onset, similar to those observed for glass
forming fluids. We explore heterogeneous relaxation in in a single constituent
lipid monolayer of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) by
measuring the rotational diffusion of a fluorescent probe,
1-palmitoyl-2-[1]-sn-glycero-3-phosphocholine (NBD-PC), using wide-field
time-resolved fluorescence anisotropy (TRFA). The observed relaxation exhibits
a narrow, liquid-like distribution at high temperatures ({\tau} ~ 2.4 ns),
consistent with previous experimental measures [1, 2]. However, as the
temperature is quenched, the distribution broadens, and we observe the
appearance of a long relaxation population ({\tau} ~ 16.5 ns). This supports
the heterogeneity observed for lipids at high packing densities, and
demonstrates that the nanoscale diffusion and reorganization in lipid
structures can be significantly complex, even in the simplest amorphous
architectures. Dynamical heterogeneity of this form can have a significant
impact on the organization, permeability and energetics of lipid membrane
structures.

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The categories of this paper are: hep-ex
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The categories of this paper are: physics
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
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The categories of this paper are: econ
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The categories of this paper are: nlin
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The categories of this paper are: cs
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The categories of this paper are: mtrl-th
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The categories of this paper are: chem-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-th
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The categories of this paper are: quant-ph
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The categories of this paper are: q-alg
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The categories of this paper are: stat
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The categories of this paper are: alg-geom
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The categories of this paper are: eess