10,846 research outputs found
Renormalizing Sznajd model on complex networks taking into account the effects of growth mechanisms
We present a renormalization approach to solve the Sznajd opinion formation
model on complex networks. For the case of two opinions, we present an
expression of the probability of reaching consensus for a given opinion as a
function of the initial fraction of agents with that opinion. The calculations
reproduce the sharp transition of the model on a fixed network, as well as the
recently observed smooth function for the model when simulated on a growing
complex networks.Comment: 5 pages, 7 figure
Interplay between chiral and axial symmetries in a SU(2) Nambu--Jona-Lasinio Model with the Polyakov loop
We consider a two flavor Polyakov--Nambu--Jona-Lasinio (PNJL) model where the
Lagrangian includes an interaction term that explicitly breaks the U
anomaly. At finite temperature, the restoration of chiral and axial symmetries,
signaled by the behavior of several observables, is investigated. We compare
the effects of two regularizations at finite temperature, one of them, that
allows high momentum quarks states, leading to the full recovery of chiral
symmetry. From the analysis of the behavior of the topological susceptibility
and of the mesonic masses of the axial partners, it is found in the SU(2) model
that, unlike the SU(3) results, the recovery of the axial symmetry is not a
consequence of the full recovery of the chiral symmetry. Thus, one needs to use
an additional idea, by means of a temperature dependence of the anomaly
coefficient, that simulates instanton suppression effects.Comment: 21 pages, 5 figures; PRD versio
CVD of CrO2 Thin Films: Influence of the Deposition Parameters on their Structural and Magnetic Properties
This work reports on the synthesis of CrO2 thin films by atmospheric pressure
CVD using chromium trioxide (CrO3) and oxygen. Highly oriented (100) CrO2 films
containing highly oriented (0001) Cr2O3 were grown onto Al2O3(0001) substrates.
Films display a sharp magnetic transition at 375 K and a saturation
magnetization of 1.92 Bohr magnetons per f.u., close to the bulk value of 2
Bohr magnetons per f.u. for the CrO2.
Keywords: Chromium dioxide (CrO2), Atmospheric pressure CVD, Spintronics.Comment: 5 pages, 6 figure
Chaos and Synchronized Chaos in an Earthquake Model
We show that chaos is present in the symmetric two-block Burridge-Knopoff
model for earthquakes. This is in contrast with previous numerical studies, but
in agreement with experimental results. In this system, we have found a rich
dynamical behavior with an unusual route to chaos. In the three-block system,
we see the appearance of synchronized chaos, showing that this concept can have
potential applications in the field of seismology.Comment: To appear in Physical Review Letters (13 pages, 6 figures
Influence of wood storage time in the paper properties of Eucalyptus globulus
In this work we studied the effect of moisture and chip pile storage time of Eucalyptus globulus wood, regarding the impact in kraft cooking and papermaking.
Experimentally, chip samples were collected with different storage times (0, 15, 30, 60 and 90 days) from two distinct piles (wet and dry). The cooked chips after disintegration, screening and washing were submitted to a bleaching stage, in ECF sequence following five stages (D0E1D1E2D2). The pulps were beaten in a PFI mill at 1000, 2000 and 3000 revolutions. For the cooking results we observed higher yield and lower alkali consumption for the wet pile chips and lower storage time (15 days).
The results showed that storage time is a significant factor (ANOVA results) for almost paper properties studied and influenced mainly the internal fibre links. For what paper properties are concerned, the difference between piles isn’t so evident, the major differences are observed for the lower storage time (15 days)
Research-based spin-offs as agents of knowledge dissemination: Evidence from the analysis of innovation networks
The paper addresses the role played by research-based spin-offs (RBSOs) as knowledge dissemination
mechanisms, through their position in knowledge networks. For this purpose the paper analyses the formal
networks established by Portuguese RBSOs, in the context of publicly funded research, technology and precommercial product development projects, and investigates their configuration along two levels. At
organisational level, in order to understand whether RBSOs extend their reach beyond the academic sphere;
and if they do, whether they connect to organisations located downstream in the knowledge value chain, and
which is their position in networks involving both research organisations and other firms. At spatial level, in
order to understand whether RBSOs extend their reach beyond the region where they are created, thus
potentially acting as connectors between diverse regions. The analysis starts from the population of RBSOs
created in Portugal until 2007 (327 firms) and identifies those that have established formal technological
relationships, as part of projects funded by all the relevant programmes launched in the period 1993-2012. As
a result, the analysis encompasses 192 collaborative projects and involves 82 spin-offs and 281 partners, of
which only 20% are research organisations, the remaining being other firms and a variety of other
downstream organisations. The results, although still preliminary, provide some insights into the knowledge
networking behaviour of the RBSOs. As expected, research organisations are a central actor in spin-offs’
networks, being the sole partner for some of them. But half of the RBSOs have moved beyond the academic
sphere, being frequently a central element in tripartite technological relationships between research and other
organisations, and occupying an intermediation position in the network, thus potentially acting as facilitators
in knowledge circulation and transformation. Also as expected, RBSOs are predominantly located in the main
metropolitan areas and tend to relate with organisations similarly located. But while geographical proximity
emerges as important in the choice of partners, in about half of the cases, RBSOs knowledge networks have
extended beyond regional boundaries. Given their central position in the network, this suggests a role as
connectors across regions that will be explored in subsequent research.info:eu-repo/semantics/publishedVersio
Statistical Dynamics of Religions and Adherents
Religiosity is one of the most important sociological aspects of populations.
All religions may evolve in their beliefs and adapt to the society
developments. A religion is a social variable, like a language or wealth, to be
studied like any other organizational parameter.
Several questions can be raised, as considered in this study: e.g. (i) from a
``macroscopic'' point of view : How many religions exist at a given time? (ii)
from a ``microscopic'' view point: How many adherents belong to one religion?
Does the number of adherents increase or not, and how? No need to say that if
quantitative answers and mathematical laws are found, agent based models can be
imagined to describe such non-equilibrium processes.
It is found that empirical laws can be deduced and related to preferential
attachment processes, like on evolving network; we propose two different
algorithmic models reproducing as well the data. Moreover, a population
growth-death equation is shown to be a plausible modeling of evolution dynamics
in a continuous time framework. Differences with language dynamic competition
is emphasized.Comment: submitted to EP
Inter-industrial relationships driving the blue economy industrial transformation
The “Blue Economy” is considered one of the drivers of European growth, based on the development of new competences and activities that enable a sustainable exploitation of ocean resources (EC, 2021; Howard, 2018). Strategies and policies were formulated, both at the UE and national levels, to address “Blue growth”, combining industrial growth objectives with sustainability concerns. These strategies have targeted a broad variety of actors engaged in ocean-related activities, namely companies from established and new industries, and have promoted the development of new transversal technologies through the support of research and innovation (Sousa et al, 2020; EC, 2012).info:eu-repo/semantics/publishedVersio
Some properties of two Nambu--Jona-Lasinio -type models with inputs from lattice QCD
We investigate the phase diagram of the so-called
Polyakov--Nambu--Jona-Lasinio (PNJL) model at finite temperature and nonzero
chemical potential. The calculations are performed in the light and strange
quark sectors (, , ), which includes the 't Hooft instanton induced
interaction term that breaks the axial symmetry, and the quarks are coupled to
the (spatially constant) temporal background gauge field. On one hand, a
special attention is payed to the critical end point (CEP). The strength of the
flavor-mixing interaction alters the CEP location, since when it becomes weaker
the CEP moves to low temperatures and can even disappear. On the other hand, we
also explore the connection between QCD, a nonlocal Nambu--Jona-Lasinio type
model and the Landau gauge gluon propagator. Possible links between the
quenched gluon propagator and low energy hadronic phenomenology are
investigated.Comment: Contribution to the International Meeting "Excited QCD", Peniche,
Portugal, 06 - 12 May 201
Desenvolvimento de mudas de Portulacaria afra Jacq. oriundas de diferentes explantes e irrigadas com água salina.
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