20,504 research outputs found
A Growth model for DNA evolution
A simple growth model for DNA evolution is introduced which is analytically
solvable and reproduces the observed statistical behavior of real sequences.Comment: To be published in Europhysics Letter
Evaluation of analytical methodologies to derive vulnerability functions
The recognition of fragility functions as a fundamental tool in seismic risk assessment has led to the
development of more and more complex and elaborate procedures for their computation. Although vulnerability
functions have been traditionally produced using observed damage and loss data, more recent studies propose the
employment of analytical methodologies as a way to overcome the frequent lack of post-earthquake data. The
variation of the structural modelling approaches on the estimation of building capacity has been the target of
many studies in the past, however, its influence in the resulting vulnerability model, impact in loss estimations or
propagation of the uncertainty to the seismic risk calculations has so far been the object of restricted scrutiny.
Hence, in this paper, an extensive study of static and dynamic procedures for estimating the nonlinear response
of buildings has been carried out in order to evaluate the impact of the chosen methodology on the resulting
vulnerability and risk outputs. Moreover, the computational effort and numerical stability provided by each
approach were evaluated and conclusions were obtained regarding which one offers the optimal balance between
accuracy and complexity
Ab initio calculation of the dynamical properties of PPP and PPV
In this work, we have calculated the vibrational modes and frequencies of the
crystalline PPP (in both the Pbam and Pnnm symmetries) and PPV (in the P21/c
symmetry). Our results are in good agreement with the available experimental
data. Also, we have calculated the temperature dependence of their specific
heats at constant volume, and of their vibrational entropies. Based on our
results, at high temperatures, the PPP is more stable in the Pnnm structure
than in the Pbam one.Comment: 5 pages, 7 figures, accepted for publication in Braz. J. Phys.,
special number, Proceedings of BWSP-12, 12th Brazilian Workshop on
Semiconductor Physic
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
Experimental characterization of the structural response of adobe arches
Earth was one of the first construction materials used by mankind and has been used as a building material since ancient times until the present days. Its qualities related to thermal comfort, low cost or simple construction techniques have contributed to such a long tradition throughout the world with several different architectural expressions, integrating the culture and history of each region.
With the wide propagation of steel and concrete structures, there has been a general loss of the traditional knowledge in earth construction. This type of construction presents important structural fragilities and requires a special maintenance to preserve its qualities. In order to understand the structural behaviour of this type of structures, the associated construction methods and processes have to be considered.
Aveiro University has been developing studies on adobe constructions, with research on the material mechanical characterization, experimental study of the structural behaviour of adobe masonry walls and, more recently, in the development of a detailed survey methodology for the characterization of buildings in Aveiro district.
Integrated in these studies, arches with different geometries were built using adobe blocks and traditional construction methods. These arches were tested under different types of vertical loading (distributed symmetrical, distributed non-symmetrical and point load) until collapse. The experimental tests performed reproduce the typical loading conditions of these structures during construction and use. The tests conducted, the results obtained and the main conclusions attained are described in this paper
The QCD Critical End Point in the Context of the Polyakov--Nambu--Jona-Lasinio Model
We investigate the phase diagram of the so-called
Polyakov--Nambu--Jona-Lasinio model at finite temperature and nonzero chemical
potential with three quark flavors. Chiral and deconfinement phase transitions
are discussed, and the relevant order-like parameters are analyzed. A special
attention is payed to the critical end point (CEP): the influence of the
strangeness on the location of the CEP is studied; also the strength of the
flavor-mixing interaction alters the CEP location, once when it becomes weaker
the CEP moves to low temperatures and can even disappear.Comment: Prepared for Strangeness in Quark Matter 2011, Sept. 18--24, Cracow,
Polan
Exploring the role of model parameters and regularization procedures in the thermodynamics of the PNJL model
The equation of state and the critical behavior around the critical end point
are studied in the context of the Polyakov--Nambu--Jona--Lasinio model. We
prove that a convenient choice of the model parameters is crucial to get the
correct description of isentropic trajectories. The physical relevance of the
effects of the regularization procedure is insured by the agreement with
general thermodynamic requirements. The results are compared with simple
thermodynamic expectations and lattice data.Comment: Talk given at XIII International Conference on Hadron Spectroscopy
(Hadron 2009), Tallahassee, Florida, USA, 29 Nov - 4 Dec, 200
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