Quantum decay of metastable states in small magnetic particles

We present an imaginary-time path-integral study of the problem of quantum decay of a metastable state of a uniaxial magnetic particle placed in the magnetic field at an arbitrary angle. Our findings agree with earlier results of Zaslavskii obtained by mapping the spin Hamiltonian onto a particle Hamiltonian. In the limit of low barrier, weak dependence of the decay rate on the angle is found, except for the field which is almost normal to the anisotropy axis, where the rate is sharply peaked, and for the field approaching the parallel orientation, where the rate rapidly goes to zero. This distinct angular dependence, together with the dependence of the rate on the field strength, provides an independent test for macroscopic spin tunneling.

Solubility and Seeded Metastable Zone width of functional sugar L-arabinose

L-arabinose is widely used in food, medicine, chemistry, and biology fields; however, solubility and seeded metastable zone width (MSZW) of L-arabinose have not been reported in the literature. In this paper, solubility and MSZW of L-arabinose in aqueous solution were determined. Solubility of L-arabinose was measured in the range of 20-68 °C by a conventional equilibrium solubility method and quantitation was determined using the ion chromatography technique. Seeded MSZW was determined in the range of 51-73% by the calorimetric method. The effect of two salts (potassium chloride and calcium chloride) on the solubility and MSZW of L-arabinose were also evaluated. Results showed that both potassium chloride and calcium chloride increased the solubility of L-arabinose, and this increase was intensified with temperature rise. The MSZW of L-arabinose was not constant but a spread. Potassium chloride increased the MSZW of L-arabinose. However, the effect of calcium chloride on MSZW of L-arabinose was concentration dependent. Conclusion: the L-arabinose solubility increased with the increase in temperature, and both potassium chloride and calcium chloride increased the solubility of L-arabinose in aqueous solution. The seeded MSZW of L-arabinose is not a constant; it increases in the presence of potassium chloride and varies with the change in calcium chloride concentration.

Metastable States and Irregular Behaviour in a Josephson Junction with Nonlinear Resistance

We consider a resistively shunted Josephson junction with a resistance that depends inversely on voltage. It is shown that such a junction in the underdamped case can give rise to extremely long-lived metastable states even in the absence of external noise. We investigate numerically this metastable state and its transition to a chaotic state. The junction voltages corresponding to these states are studied.

Finite-size scaling analysis of the avalanches in the three-dimensional Gaussian random-field Ising model with metastable dynamics

A numerical study is presented of the third-dimensional Gaussian random-field Ising model at T=0 driven by an external field. Standard synchronous relaxation dynamics is employed to obtain the magnetization versus field hysteresis loops. The focus is on the analysis of the number and size distribution of the magnetization avalanches. They are classified as being nonspanning, one-dimensional-spanning, two-dimensional-spanning, or three-dimensional-spanning depending on whether or not they span the whole lattice in different space directions. Moreover, finite-size scaling analysis enables identification of two different types of nonspanning avalanches (critical and noncritical) and two different types of three-dimensional-spanning avalanches (critical and subcritical), whose numbers increase with L as a power law with different exponents. We conclude by giving a scenario for avalanche behavior in the thermodynamic limit.

Spanning avalanches in the three-dimensional Gaussian random-field Ising model with metastable dynamics: Field dependence and geometrical properties

Spanning avalanches in the 3D Gaussian Random Field Ising Model (3D-GRFIM) with metastable dynamics at T=0 have been studied. Statistical analysis of the field values for which avalanches occur has enabled a Finite-Size Scaling (FSS) study of the avalanche density to be performed. Furthermore, a direct measurement of the geometrical properties of the avalanches has confirmed an earlier hypothesis that several types of spanning avalanches with two different fractal dimensions coexist at the critical point. We finally compare the phase diagram of the 3D-GRFIM with metastable dynamics with the same model in equilibrium at T=0.

Diluted three-dimensional random field Ising model at zero temperature with metastable dynamics.

The influence of vacancy concentration on the behavior of the three-dimensional random field Ising model with metastable dynamics is studied. We have focused our analysis on the number of spanning avalanches which allows us a clear determination of the critical line where the hysteresis loops change from continuous to discontinuous. By a detailed finite-size scaling analysis we determine the phase diagram and numerically estimate the critical exponents along the whole critical line. Finally, we discuss the origin of the curvature of the critical line at high vacancy concentration.

Quantum decay of metastable states in small magnetic particles

We present an imaginary-time path-integral study of the problem of quantum decay of a metastable state of a uniaxial magnetic particle placed in the magnetic field at an arbitrary angle. Our findings agree with earlier results of Zaslavskii obtained by mapping the spin Hamiltonian onto a particle Hamiltonian. In the limit of low barrier, weak dependence of the decay rate on the angle is found, except for the field which is almost normal to the anisotropy axis, where the rate is sharply peaked, and for the field approaching the parallel orientation, where the rate rapidly goes to zero. This distinct angular dependence, together with the dependence of the rate on the field strength, provides an independent test for macroscopic spin tunneling.

Tender puentes : materiales de EL2 y Ciencias Sociales.

Los datos de ISBN y D.L. han sido tomados de los créditos del CD-ROM, en la carátula del mismo consta: 978-84-691-8422-6 y AS-07594-2008

Interculturalidad, EL2 y didáctica de L2.

Portal de recursos sobre las competencias clave para la realización y desarrollo personal del individuo, la ciudadanía activa, la inclusión social y el empleo. Se recoge una breve presentación del tema y una selección de documentación para facilitar la aproximación a su conocimiento. Las secciones de que consta son: educación para un mundo en cambio; el proceso hacia las competencias; el concepto de competencia; currículo, evaluación y metodologías; ejemplo de desarrollo: competencia en lengua extranjera; y retos y consecuencias.

Tareas Epa: enfoque por tareas y enseñanzas en EL2 para la educación permanente.

Portal de recursos para la enseñanza y aprendizaje del español para el alumnado inmigrante. Su principal objetivo es ofrecer una reflexión teórica ligada a la práctica, promoviendo el conocimiento, la crítica, el análisis y la ejemplificación de soluciones aportadas por especialistas y autores de materiales en los ámbitos de interculturalidad y enseñanza-aprendizaje de español. Se publican reflexiones teóricas, unidades didácticas y propuestas de explotación de recursos que aplican el método didáctico del enfoque para la enseñanza-aprendizaje de una segunda lengua.

Las bibliotecas públicas y el aprendizaje de EL2 (español segunda lengua) : una propuesta para la igualdad, la participación y la interculturalidad con alumnado inmigrante.

Memoria de máster (Universidad Antonio de Nebrija, 2008). Resumen basado en el de la publicación

El cine como recurso didáctico en EL2 : modelo de explotación de la película 'Roma' de Adolfo Aristarain.

Título del encuentro: 'Hispanoamérica en el aula de ELE', organizado por el Instituto Cervantes de Nápoles

El tratamiento de las variedades de español en los manuales de EL2-LE.

Memoria de máster (UNED, 2010). Resumen basado en el de la publicación

No frunzas el ce??o, ni arrugues la nariz : las colocaciones en la ense??anza de EL2

Resumen basado en el de la publicaci??n