1,348 research outputs found
Thermal Conductance for Single Wall Carbon Nanotubes
We report a theoretical analysis of the phonon thermal conductance, \kappa
(T), for single wall carbon nanotubes (SWCN). In a range of low temperatues up
to 100K, \kappa (T) of perfect SWCN is found to increase with temperature,
approximately, in a parabolic fashion. This is qualitatively consistent with
recent experimental measurements where the tube-tube interactions are
negligibly weak. When the carbon-carbon bond length is slightly varied, \kappa
(T) is found to be qualitatively unaltered which implies that the anharmonic
effect does not change the qualitative behavior of \kappa (T).Comment: Revtex, 4 figure
Critical size of ego communication networks
With the help of information and communication technologies, studies on the
overall social networks have been extensively reported recently. However,
investigations on the directed Ego Communication Networks (ECNs) remain
insufficient, where an ECN stands for a sub network composed of a centralized
individual and his/her direct contacts. In this paper, the directed ECNs are
built on the Call Detail Records (CDRs), which cover more than 7 million people
of a provincial capital city in China for half a year. Results show that there
is a critical size for ECN at about 150, above which the average emotional
closeness between ego and alters drops, the balanced relationship between ego
and network collapses, and the proportion of strong ties decreases. This paper
not only demonstrate the significance of ECN size in affecting its properties,
but also shows accordance with the "Dunbar's Number". These results can be
viewed as a cross-culture supportive evidence to the well-known Social Brain
Hypothesis (SBH).Comment: 6 pages, 4 figures, 1 tabl
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