207,137 research outputs found
Synchronization in Complex Systems Following the Decision Based Queuing Process: The Rhythmic Applause as a Test Case
Living communities can be considered as complex systems, thus a fertile
ground for studies related to their statistics and dynamics. In this study we
revisit the case of the rhythmic applause by utilizing the model proposed by
V\'azquez et al. [A. V\'azquez et al., Phys. Rev. E 73, 036127 (2006)]
augmented with two contradicted {\it driving forces}, namely: {\it
Individuality} and {\it Companionship}. To that extend, after performing
computer simulations with a large number of oscillators we propose an
explanation on the following open questions (a) why synchronization occurs
suddenly, and b) why synchronization is observed when the clapping period
() is ( is the mean self period
of the spectators) and is lost after a time. Moreover, based on the model, a
weak preferential attachment principle is proposed which can produce complex
networks obeying power law in the distribution of number edges per node with
exponent greater than 3.Comment: 16 pages, 5 figure
Varying the Explanatory Span: Scientific Explanation for Computer Simulations
This article aims to develop a new account of scientific explanation for computer simulations. To this end, two questions are answered: what is the explanatory relation for computer simulations? And what kind of epistemic gain should be expected? For several reasons tailored to the benefits and needs of computer simulations, these questions are better answered within the unificationist model of scientific explanation. Unlike previous efforts in the literature, I submit that the explanatory relation is between the simulation model and the results of the simulation. I also argue that our epistemic gain goes beyond the unificationist account, encompassing a practical dimension as well
Viscoelasticity and primitive path analysis of entangled polymer liquids: From f-actin to polyethylene
We combine computer simulations and scaling arguments to develop a unified
view of polymer entanglement based on the primitive path analysis (PPA) of the
microscopic topological state. Our results agree with experimentally measured
plateau moduli for three different polymer classes over a wide rangeof reduced
polymer densities: (i) semi-dilute theta solutions of synthetic polymers, (ii)
the corresponding dense melts above the glass transition or crystallization
temperature, and (iii) solutions of semi-flexible (bio)polymers such as f-actin
or suspensions of rodlike viruses. Together these systems cover the entire
range from loosely to tightly entangled polymers. In particular, we argue that
the primitive path analysis renormalizes a loosely to a tightly entangled
system and provide a new explanation of the successful Lin-Noolandi packing
conjecture for polymer melts.Comment: To appear in J. Chem. Phys
On the narrative form of simulations.
Understanding complex physical systems through the use of simulations often takes on a narrative character. That is, scientists using simulations seek an understanding of processes occurring in time by generating them from a dynamic model, thereby producing something like a historical narrative. This paper focuses on simulations of the Diels-Alder reaction, which is widely used in organic chemistry. It calls on several well-known works on historical narrative to draw out the ways in which use of these simulations mirrors aspects of narrative understanding: Gallie for "followability" and "contingency"; Mink for "synoptic judgment"; Ricoeur for "temporal dialectic"; and Hawthorn for a related dialectic of the "actual and the possible". Through these reflections on narrative, the paper aims for a better grasp of the role that temporal development sometimes plays in understanding physical processes and of how considerations of possibility enhance that understanding
The Self-Organization of Speech Sounds
The speech code is a vehicle of language: it defines
a set of forms used by a community to carry information.
Such a code is necessary to support the linguistic
interactions that allow humans to communicate.
How then may a speech code be formed prior to the
existence of linguistic interactions?
Moreover, the human speech code is discrete and compositional,
shared by all the individuals of a community but different
across communities, and phoneme inventories are characterized by
statistical regularities. How can a speech code with these properties form?
We try to approach these questions in the paper,
using the ``methodology of the artificial''. We
build a society of artificial agents, and detail a mechanism that
shows the formation of a discrete speech code without pre-supposing
the existence of linguistic capacities or of coordinated interactions.
The mechanism is based on a low-level model of
sensory-motor interactions. We show that the integration of certain very
simple and non language-specific neural devices
leads to the formation of a speech code that
has properties similar to the human speech code.
This result relies on the self-organizing properties of a generic
coupling between perception and production
within agents, and on the interactions between agents.
The artificial system helps us to develop better intuitions on how speech
might have appeared, by showing how self-organization
might have helped natural selection to find speech
Closing the door on quantum nonlocality
Bell-type inequalities are proven using oversimplified probabilistic models and/or
counterfactual definiteness (CFD). If setting-dependent variables describing measuring instruments
are correctly introduced, none of these inequalities may be proven. In spite of this, a belief in a
mysterious quantum nonlocality is not fading. Computer simulations of Bell tests allow people to
study the different ways in which the experimental data might have been created. They also allow for
the generation of various counterfactual experiments’ outcomes, such as repeated or simultaneous
measurements performed in different settings on the same “photon-pair”, and so forth. They allow
for the reinforcing or relaxing of CFD compliance and/or for studying the impact of various “photon
identification procedures”, mimicking those used in real experiments. Data samples consistent
with quantum predictions may be generated by using a specific setting-dependent identification
procedure. It reflects the active role of instruments during the measurement process. Each of the
setting-dependent data samples are consistent with specific setting-dependent probabilistic models
which may not be deduced using non-contextual local realistic or stochastic hidden variables. In this
paper, we will be discussing the results of these simulations. Since the data samples are generated in
a locally causal way, these simulations provide additional strong arguments for closing the door on
quantum nonlocality
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