14,089 research outputs found
New family of potentials with analytical twiston-like solutions
In this letter we present a new approach to find analytical twiston models.
The effective two-field model was constructed by a non-trivial combination of
two one field systems. In such an approach we successfully build analytical
models which are satisfied by a combination of two defect-like solutions, where
one is responsible to twist the molecular chain by , while the other
implies in a longitudinal movement. Such a longitudinal movement can be fitted
to have the size of the distance between adjacent molecular groups. The
procedure works nicely and can be used to describe the dynamics of several
other molecular chains.Comment: 7 pages, 3 figure
Science-religion dialogue in education: religion teachers’ perceptions in a roman-catholic context
This paper examines the relationship between science and religion in the education system of Roman-Catholic Portuguese society. In particular, we explored perceptions of the relationship between science and religion for religious education teachers. We surveyed 198 Portuguese religious education teachers about how they view science and religion. The questionnaires’ results revealed a number of similarities: religious education teachers are highly involved in religious practices and exposed to science; they perceived a compatibility between science and religion; and they have an openness to dialogue between both. They do not adhere to anti-scientific perspectives, but they simultaneously try to limit what can be explained by science. Thus, an interpretative view of dialogue and/or integration seems to best explain the perceptions of religious education teachers of the relationship between science and religion. These findings allow a space of discussion, enabling teachers to possibly foster the science-religion dialogue in their contexts of pedagogical activity.info:eu-repo/semantics/acceptedVersio
Ferromagnetic tendency at the surface of CE charge-ordered manganites
Most previous investigations have shown that the surface of a ferromagnetic
material may have antiferromagnetic tendencies. However, experimentally the
opposite effect has been recently observed: ferromagnetism appears in some
nano-sized manganites with a composition such that the antiferromagnetic
charge-ordered CE state is observed in the bulk. A possible origin is the
development of ferromagnetic correlations at the surface of these small
systems. To clarify these puzzling experimental observations, we have studied
the two-orbital double-exchange model near half-doping n=0.5, using open
boundary conditions to simulate the surface of either bulk or nano-sized
manganites. Considering the enhancement of surface charge density due to a
possible AO termination (A = trivalent/divalent ion composite, O = oxygen), an
unexpected surface phase-separated state emerges when the model is studied
using Monte Carlo techniques on small clusters. This tendency suppresses the CE
charge ordering and produces a weak ferromagnetic signal that could explain the
experimental observations.Comment: 8 pages, 5 figure
Prognostic Factors of Tympanoplasty Type I in Pediatric Population – 4 Years Series of Dona Estefânia Hospital (HDE) of Centro Hospitalar Lisboa CentraL (CHLC –EPE)
Objetivos: Identificação de fatores de prognóstico em crianças submetidas a timpanoplastia tipo I.
Materiais e mĂ©todos: Estudo retrospetivo baseado na análise de todos os processos clĂnicos de crianças atá aos 15 anos de idade, submetidas a timpanoplastia tipo I de Portmann durante um perĂodo de 4 anos.
Resultados: Das 260 timpanoplastias realizadas neste perĂodo no serviço foram incluĂdos no estudo apenas 109 crianças. Das timpanoplastias realizadas, obteve-se sucesso cirĂşrgico em 68.8%, nĂŁo se tendo identificado fatores de mau prognĂłstico cirĂşrgico com significância estatĂstica.
Conclusões: As timpanoplastias tipo I em crianças sĂŁo um procedimento válido e com elevada taxa de sucesso, nĂŁo tendo sido identificado qualquer fator de mau prognĂłstico cirĂşrgico com significado estatĂstico.info:eu-repo/semantics/publishedVersio
Testing the performance of warehousing rival policies through discrete event simulation
This research tested the performance of alternative warehouse designs concerning the picking process. Travel Distance and Total Fulfillment Time were the chosen measures. An explanatory case study was built up around a model implemented with SIMUL8. Hypotheses were set by selecting outcomes of the literature survey matching popular
empirical findings. 15% reductions were found out for Total Fulfillment Time and Resource Utilisation, which was used as a proxy for operational efficiency. Literal replication of theoretical data patterns was considered as an internal validity sign. Assessing estimated changes benefits ahead of implementation was found out as a relevant contribution to practice.info:eu-repo/semantics/acceptedVersio
Irrigação do arroz de terras altas em função da porcentagem de cobertura do solo pela palhada, no sistema plantio direto.
Introdução; Coeficiente do tanque; Coeficiente de cultura; Controle de irrigação.bitstream/CNPAF/23535/1/circ_69.pd
Time Resolution and Linearity Measurements for a Scintillating Fiber Detector Instrumented with VLPC's
The time resolution for a charged particle detection is reported for a
typical scintillating fiber detector instrumented with Rockwell HISTE-IV
Visible Light Photon Counters. The resolution measurements are shown to agree
with a simple Monte Carlo model, and the model is used to make recomendations
for improved performance. In addition, the gain linearity of a sample of VLPC
devices was measured. The gain is shown to be linear for incident light
intensities which produce up to approximately 600 photoelectrons per event.Comment: 18 pages, 14 figures; Submitted to Nucl. Instr & Meth. in Phys. Res.
A; Please direct correspondence to [email protected]
Statics and dynamics of an Ashkin-Teller neural network with low loading
An Ashkin-Teller neural network, allowing for two types of neurons is
considered in the case of low loading as a function of the strength of the
respective couplings between these neurons. The storage and retrieval of
embedded patterns built from the two types of neurons, with different degrees
of (in)dependence is studied. In particular, thermodynamic properties including
the existence and stability of Mattis states are discussed. Furthermore, the
dynamic behaviour is examined by deriving flow equations for the macroscopic
overlap. It is found that for linked patterns the model shows better retrieval
properties than a corresponding Hopfield model.Comment: 20 pages, 6 figures, Latex with postscript figures in one tar.gz fil
Transport on exploding percolation clusters
We propose a simple generalization of the explosive percolation process
[Achlioptas et al., Science 323, 1453 (2009)], and investigate its structural
and transport properties. In this model, at each step, a set of q unoccupied
bonds is randomly chosen. Each of these bonds is then associated with a weight
given by the product of the cluster sizes that they would potentially connect,
and only that bond among the q-set which has the smallest weight becomes
occupied. Our results indicate that, at criticality, all finite-size scaling
exponents for the spanning cluster, the conducting backbone, the cutting bonds,
and the global conductance of the system, change continuously and significantly
with q. Surprisingly, we also observe that systems with intermediate values of
q display the worst conductive performance. This is explained by the strong
inhibition of loops in the spanning cluster, resulting in a substantially
smaller associated conducting backbone.Comment: 4 pages, 4 figure
- …