1,647 research outputs found
Induced order and reentrant melting in classical two-dimensional binary clusters
A binary system of classical charged particles interacting through a dipole
repulsive potential and confined in a two-dimensional hardwall trap is studied
by Brownian dynamics simulations. We found that the presence of small particles
\emph{stabilizes} the angular order of the system as a consequence of radial
fluctuations of the small particles. There is an optimum in the increased
rigidity of the cluster as function of the number of small particles. The small
(i.e. defect) particles melt at a lower temperature compared to the big
particles and exhibit a \emph{reentrant} behavior in its radial order that is
induced by the intershell rotation of the big particles.Comment: 7 pages, 3 figure
Structural transitions in vertically and horizontally coupled parabolic channels of Wigner crystals
Structural phase transitions in two vertically or horizontally coupled
channels of strongly interacting particles are investigated. The particles are
free to move in the -direction but are confined by a parabolic potential in
the -direction. They interact with each other through a screened power-law
potential (). In vertically coupled systems the channels
are stacked above each other in the direction perpendicular to the
-plane, while in horizontally coupled systems both channels are aligned
in the confinement direction. Using Monte Carlo (MC) simulations we obtain the
ground state configurations and the structural transitions as a function of the
linear particle density and the separation between the channels. At zero
temperature the vertically coupled system exhibits a rich phase diagram with
continuous and discontinuous transitions. On the other hand the vertically
coupled system exhibits only a very limited number of phase transitions due to
its symmetry. Further we calculated the normal modes for the Wigner crystals in
both cases. From MC simulations we found that in the case of vertically coupled
systems the zigzag transition is only possible for low densities. A
Ginzburg-Landau theory for the zigzag transition is presented, which predicts
correctly the behavior of this transition from which we interpret the
structural phase transition of the Wigner crystal through the reduction of the
Brillouin zone.Comment: 9 pages, 13 figure
Hysteresis and re-entrant melting of a self-organized system of classical particles confined in a parabolic trap
A self-organized system composed of classical particles confined in a
two-dimensional parabolic trap and interacting through a potential with a
short-range attractive part and long-range repulsive part is studied as
function of temperature. The influence of the competition between the
short-range attractive part of the inter-particle potential and its long-range
repulsive part on the melting temperature is studied. Different behaviors of
the melting temperature are found depending on the screening length ()
and the strength () of the attractive part of the inter-particle potential.
A re-entrant behavior and a thermal induced phase transition is observed in a
small region of ()-space. A structural hysteresis effect is observed
as a function of temperature and physically understood as due to the presence
of a potential barrier between different configurations of the system.Comment: 8 pages, 6 figure
Conceptualising humiliation
Humiliation lacks an empirically derived definition, sometimes simply being equated with shame. We approached the conceptualisation of humiliation from a prototype perspective, identifying 61 features of humiliation, some of which are more central to humiliation (e.g. losing self-esteem) than others (e.g. shyness). Prototypical humiliation involved feeling powerless, small, and inferior in a situation in which one was brought down and in which an audience was present, leading the person to appraise the situation as unfair and resulting in a mix of emotions, most notably disappointment, anger, and shame. Some of the features overlapped with those of shame (e.g. looking like a fool, losing self-esteem, presence of an audience) whereas other features overlapped with those of anger (e.g. being brought down, unfairness). Which specific features are present may determine whether the humiliation experience becomes more shame- or anger-like (or a combination thereof)
Response-Time Analysis for Non-Preemptive Global Scheduling with {FIFO} Spin Locks
Motivated by the lack of response-time analyses for non-preemptive global scheduling that consider shared resources, this paper provides such an analysis for global job-level fixed-priority (JLFP) scheduling policies and FIFO-ordered spin locks. The proposed analysis computes response-time bounds for a set of resource-sharing jobs subject to release jitter and execution-time uncertainties by implicitly exploring all possible execution scenarios using state-abstraction and state-pruning techniques. A large-scale empirical evaluation of the proposed analysis shows it to be substantially less pessimistic than simple execution-time inflation methods, thanks to the explicit modeling of contention for shared resources and scenario-aware blocking analysis
Transition from single-file to two-dimensional diffusion of interacting particles in a quasi-one-dimensional channel
Diffusive properties of a monodisperse system of interacting particles
confined to a \textit{quasi}-one-dimensional (Q1D) channel are studied using
molecular dynamics (MD) simulations. We calculate numerically the mean-squared
displacement (MSD) and investigate the influence of the width of the channel
(or the strength of the confinement potential) on diffusion in finite-size
channels of different shapes (i.e., straight and circular). The transition from
single-file diffusion (SFD) to the two-dimensional diffusion regime is
investigated. This transition (regarding the calculation of the scaling
exponent () of the MSD ) as a
function of the width of the channel, is shown to change depending on the
channel's confinement profile. In particular the transition can be either
smooth (i.e., for a parabolic confinement potential) or rather sharp/stepwise
(i.e., for a hard-wall potential), as distinct from infinite channels where
this transition is abrupt. This result can be explained by qualitatively
different distributions of the particle density for the different confinement
potentials.Comment: 13 pages, 11 figure
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