8,772 research outputs found
Taking dibaryon fields seriously
We propose a low energy effective field theory of QCD at the scale of pion
mass for the sector, being the baryon number, which contains two
dibaryon fields in addition to the nucleons and pions. It has a well defined
counting, is renormalizable and the nucleon-nucleon scattering amplitudes are
manifestly unitary at leading order. We work out a lower energy effective
theory for nucleons with energy much lower than the pion mass and three
momentum comparable to it, which also has a well defined counting and is
renormalizable. The dibaryon fields must also be kept as explicit degrees of
freedom in this theory. We calculate the scattering amplitudes at
next-to-leading order for the and channels in this framework
and obtain an excellent description of the phase shifts for center of mass
energies in the range.Comment: 20 pages, 5 figures; misprints corrected, explanations enlarged,
references added. Journal versio
Lesson Study and Service Learning in Teacher Preparation
The aim of this paper is to share an teacher preparation experience that combines Lesson Study (LS) with a Service Learning methodology. This experience is interdisciplinary and includes three subjects from first-grade Childhood Education, carried out at University of Malaga since academic year 2014-2015.
Within this framework, our students carry out Service Learning projects for schools in our area that are designed and developed following the LS methodology. Service Learning projects go through the following phases (Puig, J., MartÃn, & Batlle, 2008): 1) Preparation by the teachers involved in the project; 2) Implementation, i.e. developing the project with the students; 3) Evaluation.
The implementation phase also has three sub-phases: preparation, implementation, and round-up. It is here that the LS is developed through the following phases (Soto & Pérez, 2015): 1. Define the problem; 2. Co-operatively design an experimental lesson and its observation process; 3. First experimental lesson; 4. Analyse and review the lesson; 5. Second experimental lesson; 6. Analysis and drafting of conclusions; 7. Presentation in extended context.
We were able to gather evidence on how students teachers resolved different cognitive conflicts during the process. We saw how the LS process, with its phases and cooperative work, allows them to combine creativity and unique talents in a common project that acquires meaning and relevance thanks to Service Learning. This provides a framework that facilitates the construction of solid structures related to the meaning of the educational process, and which can be used to recalibrate what it means to be a Childhood School teacher: a creative, relevant, complex experience that requires recreating the knowledge and experience that students bring with them to the University about what it means to be a Childhood School teacher.Universidad de Málaga. Campus de Excelencia Internacional AndalucÃa Tech
Metastable states influence on the magnetic behavior of the triangular lattice: Application to the spin-chain compound Ca3Co2O6
It is known that the spin-chain compound Ca3Co2O6 exhibits very interesting
plateaus in the magnetization as a function of the magnetic field at low
temperatures. The origin of them is still controversial. In this paper we study
the thermal behavior of this compound with a single-flip Monte Carlo simulation
on a triangular lattice and demonstrate the decisive influence of metastable
states in the splitting of the ferrimagnetic 1/3 plateau below 10 K. We
consider the [Co2O6]n chains as giant magnetic moments described by large Ising
spins on planar clusters with open boundary conditions. With this simple
frozen-moment model we obtain stepped magnetization curves which agree quite
well with the experimental results for different sweeping rates. We describe
particularly the out-of-equilibrium states that split the low-temperature 1/3
plateau into three steps. They relax thermally to the 1/3 plateau, which has
long-range order at the equilibrium. Such states are further analyzed with
snapshots unveiling a domain-wall structure that is responsible for the
observed behavior of the 1/3 plateau. A comparison is also given of the exact
results in small triangular clusters with our Monte Carlo results, providing
further support for our thermal description of this compound.Comment: 8 pages, 11 figures, submitted to PR
Synchronization and oscillatory dynamics in heterogeneous mutually inhibited neurons
We study some mechanisms responsible for synchronous oscillations and loss of
synchrony at physiologically relevant frequencies (10-200 Hz) in a network of
heterogeneous inhibitory neurons. We focus on the factors that determine the
level of synchrony and frequency of the network response, as well as the
effects of mild heterogeneity on network dynamics. With mild heterogeneity,
synchrony is never perfect and is relatively fragile. In addition, the effects
of inhibition are more complex in mildly heterogeneous networks than in
homogeneous ones. In the former, synchrony is broken in two distinct ways,
depending on the ratio of the synaptic decay time to the period of repetitive
action potentials (), where can be determined either from the
network or from a single, self-inhibiting neuron. With ,
corresponding to large applied current, small synaptic strength or large
synaptic decay time, the effects of inhibition are largely tonic and
heterogeneous neurons spike relatively independently. With ,
synchrony breaks when faster cells begin to suppress their less excitable
neighbors; cells that fire remain nearly synchronous. We show numerically that
the behavior of mildly heterogeneous networks can be related to the behavior of
single, self-inhibiting cells, which can be studied analytically.Comment: 17 pages, 6 figures, Kluwer.sty. Journal of Compuational Neuroscience
(in press). Originally submitted to the neuro-sys archive which was never
publicly announced (was 9802001
Variational approach for walking solitons in birefringent fibres
We use the variational method to obtain approximate analytical expressions
for the stationary pulselike solutions in birefringent fibers when differences
in both phase velocities and group velocities between the two components and
rapidly oscillating terms are taken into account. After checking the validity
of the approximation we study how the soliton pulse shape depends on its
velocity and nonlinear propagation constant. By numerically solving the
propagation equation we have found that most of these stationary solutions are
stable.Comment: LaTeX2e, uses graphicx package, 23 pages with 8 figure
Noncommutative Effects in the Black Hole Evaporation in Two Dimensions
We discuss some possible implications of a two-dimensional toy model for
black hole evaporation in noncommutative field theory. While the
noncommutativity we consider does not affect gravity, it can play an important
role in the dynamics of massless and Hermitian scalar fields in the event
horizon of a Schwarzschild black hole. We find that noncommutativity will
affect the flux of outgoing particles and the nature of its UV/IR divergences.
Moreover, we show that the noncommutative interaction does not affect Leahy's
and Unruh's interpretation of thermal ingoing and outgoing fluxes in the black
hole evaporation process. Thus, the noncommutative interaction still destroys
the thermal nature of fluxes. In the process, some nonlocal implications of the
noncommutativity are discussed.Comment: 33+1 pages, 3 eps figures, typos corrected, references added, figure
3 corrected, modifications in sections 4 and 6, version published in Phys.
Rev.
Breather turbulence versus soliton turbulence: Rogue waves, probability density functions, and spectral features
10 págs.; 12 figs.Turbulence in integrable systems exhibits a noticeable scientific advantage: it can be expressed in terms of the nonlinear modes of these systems. Whether the majority of the excitations in the system are breathers or solitons defines the properties of the turbulent state. In the two extreme cases we can call such states >breather turbulence> or >soliton turbulence.> The number of rogue waves, the probability density functions of the chaotic wave fields, and their physical spectra are all specific for each of these two situations. Understanding these extreme cases also helps in studies of mixed turbulent states when the wave field contains both solitons and breathers, thus revealing intermediate characteristics. ©2016 American Physical SocietyThe authors acknowledge the support from the Volkswagen
Stiftung. The work of JMSC was also supported by MINECO
under Contract No. TEC2015-71127-C2-1-R, and by C.A.M.
under Contract No. S2013/MIT-2790. N.D. and N.A. acknowledge
support of the Australian Research Council (Discovery
Project No. DP140100265).Peer Reviewe
Evaluación preliminar de emisiones de plomo en automóviles
El presente trabajo reporta emisiones de plomo contenido en el material particulado emitido por el escape. de una muestra tÃpica de automóviles a gasolina, mediame muestreo isocinético a volumen constante según normas de la Environmental Protection Agency de USA. Los resultados obtenidos muestran ww emisión promedio de 7.4 ± 0.68 (mg Pb · km- 1) obtenido al aplicar un ciclo de conducción representativo de la A 1·enida Bemardo O'Higgins en el área de restricción vehicular. simulado en dinamómetro de rodillos y a través de dilución variable de gases de escape. Este valor sugiere que la información utilizada en la evaluación de los inventarios de emisiones en Santiago, sobredimensiona la contribución del material particulado proveniente de vehÃculos livianos a gasolina
Influences of thermal environment on fish growth
Indexación: Scopus.Thermoregulation in ectothermic animals is influenced by the ability to effectively respond to thermal variations. While it is known that ectotherms are affected by thermal changes, it remains unknown whether physiological and/or metabolic traits are impacted by modifications to the thermal environment. Our research provides key evidence that fish ectotherms are highly influenced by thermal variability during development, which leads to important modifications at several metabolic levels (e.g., growth trajectories, microstructural alterations, muscle injuries, and molecular mechanisms). In Atlantic salmon (Salmo salar), a wide thermal range (ΔT 6.4°C) during development (posthatch larvae to juveniles) was associated with increases in key thermal performance measures for survival and growth trajectory. Other metabolic traits were also significantly influenced, such as size, muscle cellularity, and molecular growth regulators possibly affected by adaptive processes. In contrast, a restricted thermal range (ΔT 1.4°C) was detrimental to growth, survival, and cellular microstructure as muscle growth could not keep pace with increased metabolic demands. These findings provide a possible basic explanation for the effects of thermal environment during growth. In conclusion, our results highlight the key role of thermal range amplitude on survival and on interactions with major metabolism-regulating processes that have positive adaptive effects for organisms.http://onlinelibrary.wiley.com/doi/10.1002/ece3.3239/ful
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