1,534 research outputs found
Individual heterogeneity generates explosive system network dynamics
Individual heterogeneity is a key characteristic of many real-world systems,
from organisms to humans. However its role in determining the system's
collective dynamics is typically not well understood. Here we study how
individual heterogeneity impacts the system network dynamics by comparing
linking mechanisms that favor similar or dissimilar individuals. We find that
this heterogeneity-based evolution can drive explosive network behavior and
dictates how a polarized population moves toward consensus. Our model shows
good agreement with data from both biological and social science domains. We
conclude that individual heterogeneity likely plays a key role in the
collective development of real-world networks and communities, and cannot be
ignored.Comment: 6 pages, 4 figure
Chiral currents in gold nanotubes
Results are presented for the electron current in gold chiral nanotubes
(AuNTs). Starting from the band structure of (4,3) and (5,3) AuNTs, we find
that the magnitude of the chiral currents are greater than those found in
carbon nanotubes. We also calculate the associated magnetic flux inside the
tubes and find this to be higher than the case of carbon nanotubes. Although
(4,3) and (5,3) AuNTs carry transverse momenta of similar magnitudes, the
low-bias magnetic flux carried by the former is far greater than that carried
by the latter. This arises because the low-bias longitudinal current carried by
a (4,3) AuNT is significantly smaller than that of a (5,3) AuNT.Comment: 5 pages, 6 figure
Internal character dictates phase transition dynamics between isolation and cohesive grouping
We show that accounting for internal character among interacting,
heterogeneous entities generates rich phase transition behavior between
isolation and cohesive dynamical grouping. Our analytical and numerical
calculations reveal different critical points arising for different
character-dependent grouping mechanisms. These critical points move in opposite
directions as the population's diversity decreases. Our analytical theory helps
explain why a particular class of universality is so common in the real world,
despite fundamental differences in the underlying entities. Furthermore, it
correctly predicts the non-monotonic temporal variation in connectivity
observed recently in one such system
Atypical viral dynamics from transport through popular places
The flux of visitors through popular places undoubtedly influences viral
spreading -- from H1N1 and Zika viruses spreading through physical spaces such
as airports, to rumors and ideas spreading though online spaces such as
chatrooms and social media. However there is a lack of understanding of the
types of viral dynamics that can result. Here we present a minimal dynamical
model which focuses on the time-dependent interplay between the {\em mobility
through} and the {\em occupancy of} such spaces. Our generic model permits
analytic analysis while producing a rich diversity of infection profiles in
terms of their shapes, durations, and intensities. The general features of
these theoretical profiles compare well to real-world data of recent social
contagion phenomena.Comment: 14 pages, 16 figure
Proyecto de fuentes documentales etnográficas sobre indígenas de Iberoamérica en archivos eclesiásticos y civiles de Europa y América
Anomalous Contagion and Renormalization in Dynamical Networks with Nodal Mobility
The common real-world feature of individuals migrating through a network --
either in real space or online -- significantly complicates understanding of
network processes. Here we show that even though a network may appear static on
average, underlying nodal mobility can dramatically distort outbreak profiles.
Highly nonlinear dynamical regimes emerge in which increasing mobility either
amplifies or suppresses outbreak severity. Predicted profiles mimic recent
outbreaks of real-space contagion (social unrest) and online contagion
(pro-ISIS support). We show that this nodal mobility can be renormalized in a
precise way for a particular class of dynamical networks
Oscillatory combustion in rockets Third semiannual report, Jun. 1 - Nov. 30, 1965
Rocket engine oscillatory combustion studie
Effective photon mass and exact translating quantum relativistic structures
Using a variation of the celebrated Volkov solution, the Klein-Gordon
equation for a charged particle is reduced to a set of ordinary differential
equations, exactly solvable in specific cases. The new quantum relativistic
structures can reveal a localization in the radial direction perpendicular to
the wave packet propagation, thanks to a non-vanishing scalar potential. The
external electromagnetic field, the particle current density and the charge
density are determined. The stability analysis of the solutions is performed by
means of numerical simulations. The results are useful for the description of a
charged quantum test particle in the relativistic regime, provided spin effects
are not decisive
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