1,033 research outputs found
Competition and dual users in complex contagion processes
We study the competition of two spreading entities, for example innovations,
in complex contagion processes in complex networks. We develop an analytical
framework and examine the role of dual users, i.e. agents using both
technologies. Searching for the spreading transition of the new innovation and
the extinction transition of a preexisting one, we identify different phases
depending on network mean degree, prevalence of preexisting technology, and
thresholds of the contagion process. Competition with the preexisting
technology effectively suppresses the spread of the new innovation, but it also
allows for phases of coexistence. The existence of dual users largely modifies
the transient dynamics creating new phases that promote the spread of a new
innovation and extinction of a preexisting one. It enables the global spread of
the new innovation even if the old one has the first-mover advantage.Comment: 9 pages, 4 figure
Multilayer coevolution dynamics of the nonlinear voter model
We study a coevolving nonlinear voter model on a two-layer network.
Coevolution stands for coupled dynamics of the state of the nodes and of the
topology of the network in each layer. The plasticity parameter p measures the
relative time scale of the evolution of the states of the nodes and the
evolution of the network by link rewiring. Nonlinearity of the interactions is
taken into account through a parameter q that describes the nonlinear effect of
local majorities, being q = 1 the marginal situation of the ordinary voter
model. Finally the connection between the two layers is measured by a degree of
multiplexing `. In terms of these three parameters, p, q and ` we find a rich
phase diagram with different phases and transitions. When the two layers have
the same plasticity p, the fragmentation transition observed in a single layer
is shifted to larger values of p plasticity, so that multiplexing avoids
fragmentation. Different plasticities for the two layers lead to new phases
that do not exist in a coevolving nonlinear voter model in a single layer,
namely an asymmetric fragmented phase for q > 1 and an active shattered phase
for q
1, we can find two different transitions by increasing the plasticity
parameter, a first absorbing transition with no fragmentation and a subsequent
fragmentation transition
Competing contagion processes: Complex contagion triggered by simple contagion
Empirical evidence reveals that contagion processes often occur with
competition of simple and complex contagion, meaning that while some agents
follow simple contagion, others follow complex contagion. Simple contagion
refers to spreading processes induced by a single exposure to a contagious
entity while complex contagion demands multiple exposures for transmission.
Inspired by this observation, we propose a model of contagion dynamics with a
transmission probability that initiates a process of complex contagion. With
this probability nodes subject to simple contagion get adopted and trigger a
process of complex contagion. We obtain a phase diagram in the parameter space
of the transmission probability and the fraction of nodes subject to complex
contagion. Our contagion model exhibits a rich variety of phase transitions
such as continuous, discontinuous, and hybrid phase transitions, criticality,
tricriticality, and double transitions. In particular, we find a double phase
transition showing a continuous transition and a following discontinuous
transition in the density of adopted nodes with respect to the transmission
probability. We show that the double transition occurs with an intermediate
phase in which nodes following simple contagion become adopted but nodes with
complex contagion remain susceptible.Comment: 9 pages, 4 figure
Deformation and reverse snapping of a circular shallow shell under uniform edge tension
AbstractIn this paper we study the deformation and stability of a shallow shell under uniform edge tension, both theoretically and experimentally. Von Karman’s plate model is adopted to formulate the equations of motion. For a shell with axisymmetrical initial shape, the equilibrium positions can be classified into axisymmetrical and unsymmetrical solutions. While there may exist both stable and unstable axisymmetrical solutions, all the unsymmetrical solutions are unstable. Since the unsymmetrical solutions will not affect the stability of the axisymmetrical solutions, it is concluded that for quasi-static analysis, there is no need to include unsymmetrical assumed modes in the calculation. If the shell is initially in the unstrained configuration, it will only be flattened smoothly when the edge tension is applied. No snap-through buckling is possible in this case. On the other hand, if the shell is initially in the strained position, it will be snapped back to the stable position on the other side of the base plane when the edge tension reaches a critical value. Experiment is conducted on several free brass shells of different initial heights to verify the theoretical predictions. Generally speaking, for the range of initial height H<10 the experimental measurements of the deformation and the reverse snapping load agree well with theoretical predictions
Multi-particle and High-dimension Controlled Order Rearrangement Encryption Protocols
Based on the controlled order rearrange encryption (CORE) for quantum key
distribution using EPR pairs[Fu.G.Deng and G.L.Long Phys.Rev.A68 (2003)
042315], we propose the generalized controlled order rearrangement encryption
(GCORE) protocols of qubits and qutrits, concretely display them in the
cases using 3-qubit, 2-qutrit maximally entangled basis states. We further
indicate that our protocols will become safer with the increase of number of
particles and dimensions. Moreover, we carry out the security analysis using
quantum covariant cloning machine for the protocol using qutrits. Although the
applications of the generalized scheme need to be further studied, the GCORE
has many distinct features such as great capacity and high efficiency
Pilots’ visual scan pattern and situation awareness in flight operations
Introduction: Situation awareness (SA) is considered an essential prerequisite for safe flying. If the impact of visual scanning patterns on a pilot’s situation awareness could be identified in flight operations, then eye-tracking tools could be integrated with flight simulators to improve training efficiency. Method: Participating in this research were 18 qualified, mission-ready fighter pilots. The equipment included high-fidelity and fixed-base type flight simulators and mobile head-mounted eye-tracking devices to record a subject’s eye movements and SA while performing air-to-surface tasks. Results: There were significant differences in pilots’ percentage of fixation in three operating phases: preparation (M = 46.09, SD = 14.79), aiming (M = 24.24, SD = 11.03), and release and break-away (M = 33.98, SD = 14.46). Also, there were significant differences in pilots’ pupil sizes, which were largest in the aiming phase (M = 27,621, SD = 6390.8), followed by release and break-away (M = 27,173, SD = 5830.46), then preparation (M = 25,710, SD = 6078.79), which was the smallest. Furthermore, pilots with better SA performance showed lower perceived workload (M = 30.60, SD = 17.86), and pilots with poor SA performance showed higher perceived workload (M = 60.77, SD = 12.72). Pilots’ percentage of fixation and average fixation duration among five different areas of interest showed significant differences as well. Discussion: Eye-tracking devices can aid in capturing pilots’ visual scan patterns and SA performance, unlike traditional flight simulators. Therefore, integrating eye-tracking devices into the simulator may be a useful method for promoting SA training in flight operations, and can provide in-depth understanding of the mechanism of visual scan patterns and information processing to improve training effectiveness in aviation
Novel Non-apoptotic Pathway of Caspase 3 Activation During Mild Oxidative Stress
Ph.DDOCTOR OF PHILOSOPH
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