7,091 research outputs found
Hierarchical network structure as the source of power-law frequency spectra (state-trait continua) in living and non-living systems: how physical traits and personalities emerge from first principles in biophysics
What causes organisms to have different body plans and personalities? We
address this question by looking at universal principles that govern the
morphology and behavior of living systems. Living systems display a small-world
network structure in which many smaller clusters are nested within fewer larger
ones, producing a fractal-like structure with a power-law cluster size
distribution. Their dynamics show similar qualities: the timeseries of inner
message passing and overt behavior contain high frequencies or 'states' that
are nested within lower frequencies or 'traits'. Here, we argue that the nested
modular (power-law) dynamics of living systems results from their nested
modular (power-law) network structure: organisms 'vertically encode' the deep
spatiotemporal structure of their environments, so that high frequencies
(states) are produced by many small clusters at the base of a nested-modular
hierarchy and lower frequencies (traits) are produced by fewer larger clusters
at its top. These include physical as well as behavioral traits. Nested-modular
structure causes higher frequencies to be embedded in lower frequencies,
producing power-law dynamics. Such dynamics satisfy the need for efficient
energy dissipation through networks of coupled oscillators, which also governs
the dynamics of non-living systems (e.g. earthquake dynamics, stock market
fluctuations). Thus, we provide a single explanation for power-law frequency
spectra in both living and non-living systems. If hierarchical structure indeed
produces hierarchical dynamics, the development (e.g. during maturation) and
collapse (e.g. during disease) of hierarchical structure should leave specific
traces in power-law frequency spectra that may serve as early warning signs to
system failure. The applications of this idea range from embryology and
personality psychology to sociology, evolutionary biology and clinical
medicine
Modeling the emergence of modular leadership hierarchy during the collective motion of herds made of harems
Gregarious animals need to make collective decisions in order to keep their
cohesiveness. Several species of them live in multilevel societies, and form
herds composed of smaller communities. We present a model for the development
of a leadership hierarchy in a herd consisting of loosely connected sub-groups
(e.g. harems) by combining self organization and social dynamics. It starts
from unfamiliar individuals without relationships and reproduces the emergence
of a hierarchical and modular leadership network that promotes an effective
spreading of the decisions from more capable individuals to the others, and
thus gives rise to a beneficial collective decision. Our results stemming from
the model are in a good agreement with our observations of a Przewalski horse
herd (Hortob\'agy, Hungary). We find that the harem-leader to harem-member
ratio observed in Przewalski horses corresponds to an optimal network in this
approach regarding common success, and that the observed and modeled harem size
distributions are close to a lognormal.Comment: 18 pages, 7 figures, J. Stat. Phys. (2014
Low cost construction: state of the art and prospects for using structure wood apartment buildings in Portugal
The Low cost concept in buildings is normally associated with the construction of
social housing. Today, with the economic crisis, this concept becomes increasingly important to
all areas and in the different social hierarchies. Low cost architecture emerges as the demand to
find economical constructive solutions, but still allowing good visual, hygrothermal and acoustic
performances. Wood emerges as an excellent material able to achieve all these objectives.
The ease decomposition and re-composition of prefabrication wood systems allow the flexibility
of the building components, being capable of generating multiple combinatorial possibilities,
customized and capable of responding to the users’ changing requests.
This work aims to make a description of the evolution of the low cost concept within the industry
of building construction, to provide a description of the state of the art and characterization
of the potential of wood structures in multi-storey buildings, and place this type of structural
solution in the “purposes” or objectives of the low cost construction
Cortical Hubs Form a Module for Multisensory Integration on Top of the Hierarchy of Cortical Networks
Sensory stimuli entering the nervous system follow particular paths of processing, typically separated (segregated) from the paths of other modal information. However, sensory perception, awareness and cognition emerge from the combination of information (integration). The corticocortical networks of cats and macaque monkeys display three prominent characteristics: (i) modular organisation (facilitating the segregation), (ii) abundant alternative processing paths and (iii) the presence of highly connected hubs. Here, we study in detail the organisation and potential function of the cortical hubs by graph analysis and information theoretical methods. We find that the cortical hubs form a spatially delocalised, but topologically central module with the capacity to integrate multisensory information in a collaborative manner. With this, we resolve the underlying anatomical substrate that supports the simultaneous capacity of the cortex to segregate and to integrate multisensory information
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