84 research outputs found
Microscopic intervention yields abrupt transition in interdependent magnetic networks
The study of interdependent networks has recently experienced a boost with
the development of experimentally testable materials that physically realize
their critical behaviors, calling for systematic studies that go beyond the
percolation paradigm. Here we study the critical phase transition of
interdependent spatial magnetic networks model where dependency couplings
between networks are realized by a thermal interaction having a tunable spatial
range. We show how the critical phenomena and the phase diagram of this
realistic model are highly affected by the range of thermal dissipation and how
the latter changes the transition from continuous to abrupt. Furthermore, we
show that microscopic interventions of localized heating and localized magnetic
field yield a macroscopic phase transition and novel phase diagrams. Our
results provide novel and realistic insights about controlling the macroscopic
phases of interdependent materials by means of localized microscopic
interventions
Liquid-gas phase transition in finite nuclei
In a finite temperature Thomas-Fermi framework, we calculate density
distributions of hot nuclei enclosed in a freeze-out volume of few times the
normal nuclear volume and then construct the caloric curve, with and without
inclusion of radial collective flow. In both cases, the calculated specific
heats show a peaked structure signalling a liquid-gas phase transition.
Without flow, the caloric curve indicates a continuous phase transition whereas
with inclusion of flow, the transition is very sharp. In the latter case, the
nucleus undergoes a shape change to a bubble from a diffuse sphere at the
transition temperature.Comment: Proc. of 6th Int. Conf. on N-N Collisions (Gatlinburg); Nuclear
Physics A (in press
Flow effects on multifragmentation in the canonical model
A prescription to incorporate the effects of nuclear flow on the process of
multifragmentation of hot nuclei is proposed in an analytically solvable
canonical model. Flow is simulated by the action of an effective negative
external pressure. It favors sharpening the signatures of liquid-gas phase
transition in finite nuclei with increased multiplicity and a lowered phase
transition temperature.Comment: 13 pages, 5 Post Script figures (accepted for publication in PRC
Nucleation phenomena and extreme vulnerability of spatial k-core systems
K-core percolation is a fundamental dynamical process in complex networks
with applications that span numerous real-world systems. Earlier studies focus
primarily on random networks without spatial constraints and reveal intriguing
mixed-order transitions. However, real-world systems, ranging from
transportation and communication networks to complex brain networks, are not
random but are spatially embedded. Here, we study k-core percolation on
two-dimensional spatially embedded networks and show that, in contrast to
regular percolation, the length of connections can control the transition type,
leading to four different types of phase transitions associated with novel
phenomena and a rich phase diagram. A key finding is the existence of a
metastable phase in which microscopic localized damage, independent of system
size, can cause a macroscopic phase transition, a result which cannot be
achieved in traditional percolation. In this case, local failures can
spontaneously propagate the damage radially until the system entirely
collapses, a phenomenon analogous to the nucleation process. These findings
suggest novel features and extreme vulnerabilities of spatially embedded k-core
network systems, and highlight the necessity to take into account the
characteristic length of links when designing robust spatial networks.
Furthermore, our insight about the microscopic processes and their origin
during the mixed order and first order abrupt transitions in k-core networks
could shed light on the mechanisms of many systems where such transitions
occur.Comment: 12 pages, 10 figure
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