5,110 research outputs found
The group of strong Galois objects associated to a cocommutative Hopf quasigroup
Let H be a cocommutative faithfully flat Hopf quasigroup in a strict
symmetric monoidal category with equalizers. In this paper we introduce the
notion of (strong) Galois H-object and we prove that the set of isomorphism
classes of (strong) Galois H-objects is a (group) monoid which coincides, in
the Hopf algebra setting, with the Galois group of H-Galois objects introduced
by Chase and Sweedler
Time relaxation of interacting single--molecule magnets
We study the relaxation of interacting single--molecule magnets (SMMs) in
both spatially ordered and disordered systems. The tunneling window is assumed
to be, as in Fe8, much narrower than the dipolar field spread. We show that
relaxation in disordered systems differs qualitatively from relaxation in fully
occupied cubic and Fe_8 lattices. We also study how line shapes that develop in
''hole--digging'' experiments evolve with time t in these fully occupied
lattices. We show (1) that the dipolar field h scales as t^p in these hole line
shapes and show (2) how p varies with lattice structure. Line shapes are not,
in general, Lorentzian. More specifically, in the lower portion of the hole,
they behave as (h/t^p)^{(1/p)-1} if h is outside the tunnel window. This is in
agreement with experiment and with our own Monte Carlo results.Comment: 21 LaTeX pages, 6 eps figures. Submitted to PRB on 15 June 2005.
Accepted on 13 August 200
A pioneer of modernity in the illustrated press of the 19th century: Emilia Serrano de Wilson
Daremos en este artículo un repaso a la labor de las mujeres periodistas en el siglo XIX en España, sus ideas, del tradicionalismo al progresismo, y algunas de las principales publicaciones de la prensa ilustrada en las que publicaron su trabajo, y analizaremos a continuación algunas contribuciones de Emilia Serrano a esta, entre los años 1857-1874. Junto a apuntes costumbristas describiendo fiestas y vestidos, esta autora critica ciertas costumbres y la situación de la mujer en la época.We will review the role of journalist women in the Spain of the 19th century, their ideas, from traditionalism to progressivism, and some of the main publications of the illustrated press, where some of them published their work. Then, we will analyze some contributions done between 1857 and 1874 by Emilia Serrano. Along with some costumbrist articles where she describes parties and dresses, this author criticizes the situations of women in that time
Magnetization Process of Single Molecule Magnets at Low Temperatures
We show that correlations established before quenching to very low
temperatures, later drive the magnetization process of systems of single
molecule magnets, after a magnetic field is applied at t=0. We also show that
in SC lattices, m \propto sqrt(t), as observed in Fe_8, but only for
1+2*log_10(h_d/h_w) time decades, where h_d is a nearest neighbor dipolar
magnetic field and a spin reversal can occur only if the field on it is within
(-h_w,h_w). However, the sqrt(t) behavior is not universal. For BCC and FCC
lattices, m \propto t^p, but p \simeq 0.7. The value to which m finally levels
off is also given.Comment: 5 LaTeX pages, 2 figures. Submitted to Phys. Rev. Lett. on 26 January
2003, accepted on 24 July 200
Phases of anisotropic dipolar antiferromagnets
We study systems of classical magnetic dipoles on simple cubic lattices with
dipolar and antiferromagnetic exchange interactions. By analysis and Monte
Carlo (MC) simulations, we find how the antiferromagnetic phases vary with
uniaxial and fourfold anisotropy constants, C and D, as well as with exchange
strength J. We pay special attention to the spin reorientation (SR) phase, and
exhibit in detail the nature of its broken symmetries. By mean field theory and
by MC, we also obtain the ratio of the higher ordering temperature to the SR
transition temperature, and show that it depends mainly on D/C, and rather
weakly on J. We find a reverse SR transition.Comment: 10 LaTeX pages, 14 eps figures. Submitted to PRB on 03 October 2005.
Accepted on 13 December 200
Influencia del sedentarismo en las desviaciones raquídeas de la población escolar de Léon
Nuestra investigación trata de evaluar los hábitos sedentarios, en los escolares de 10 y 14 años de una zona de León, y su influencia en las desviaciones raquídeas. Para la obtención de los hábitos nos basamos en el tets de Medoza, R. también se realizó una evaluación física de los niños para observar las desviaciones raquídeas. En el tratamiento de la información se utilizó el análisis de la varianza univariante y multivariante, además del análisis de componentes principales y análisis discriminante. Llegando a la conclusión, respecto al tiempo de televisión que el día de la semana que más tiempo dedican los niños a ver la televisión es discrimante de los escolares que tienen desviación raquídea
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