Selfconsistent hybridization expansions for static properties of the Anderson impurity model

By means of a projector-operator formalism we derive an approximation based on a self consistent hybridization expansion to study the ground state properties of the Anderson Impurity model. We applied the approximation to the general case of finite Coulomb repulsion $U$, extending previous work with the same formalism in the infinite-$U$ case. The treatment provides a very accurate calculation of the ground state energy and their related zero temperature properties in the case in which $U$ is large enough, but still finite, as compared with the rest of energy scales involved in the model. The results for the valence of the impurity are compared with exact results that we obtain from equations derived using the Bethe ansatz and with a perturbative approach. The magnetization and magnetic susceptibility is also compared with Bethe ansatz results. In order to do this comparison, we also show how to regularize the Bethe ansatz integral equations necessary to calculate the impurity valence, for arbitrary values of the parameters.Comment: 8 pages, 5 figure

Simplicial Quantum Gravity

This is my PhD thesis on four-dimensional simplicial quantum gravity using the dynamical triangulation model. Most of the results we have published in separate papers are collected here for your convenience. Some new results have been added as well. Besides these results this thesis also contains an introduction to simplicial quantum gravity and a detailed description of my dynamical triangulation program for arbitrary dimension. Some small formal parts are in Dutch.Comment: 160 pages, PostScript (because you don't have all the mf fonts), replaced because of file corruptio

Crystal-field splittings in CeX (X= N, P, As, Sb, Bi) compounds

The unusual and interesting physical properties of rare earth intemetallic compounds have their origin in the combination of strongly correlated 4f states and their hybridization with the conduction electron sea, which gives rise to their complex low temperature Kondo behavior. In particular, Ce compounds are very sensitive to the crystalline and chemical environment, as compared to other rare earth systems. The interaction of the 4f state with the conduction band plays an important role in the determination of the different magnetic, structural and transport properties of these systems. Among the cerium compounds, those of the type CeX, which crystallize in the rock salt structure, exhibit extremely unusual magnetic properties. By making use of the mixed LDA-NCA calculation technique we analyse the crystal-field splittings of CeX compounds (X=N, P, As, Sb, Bi). The obtained ab-initio hybridization functions are taken as imputs to calculate the crystal-field splittings within NCA (non crossing approximation) and the tendencies are contrasted with experiments. KEY WORDS: Highly correlated systems, crystal fields, p-electron.Comment: 8 pages, 2 figure

Absence of barriers in dynamical triangulation

Due to the unrecognizability of certain manifolds there must exist pairs of triangulations of these manifolds that can only be reached from each other by going through an intermediate state that is very large. This might reduce the reliability of dynamical triangulation, because there will be states that will not be reached in practice. We investigate this problem numerically for the manifold $S^5$, which is known to be unrecognizable, but see no sign of these unreachable states.Comment: 8 pages, LaTeX2e source with postscript resul

Orbit bifurcations and the scarring of wavefunctions

We extend the semiclassical theory of scarring of quantum eigenfunctions psi_{n}(q) by classical periodic orbits to include situations where these orbits undergo generic bifurcations. It is shown that |psi_{n}(q)|^{2}, averaged locally with respect to position q and the energy spectrum E_{n}, has structure around bifurcating periodic orbits with an amplitude and length-scale whose hbar-dependence is determined by the bifurcation in question. Specifically, the amplitude scales as hbar^{alpha} and the length-scale as hbar^{w}, and values of the scar exponents, alpha and w, are computed for a variety of generic bifurcations. In each case, the scars are semiclassically wider than those associated with isolated and unstable periodic orbits; moreover, their amplitude is at least as large, and in most cases larger. In this sense, bifurcations may be said to give rise to superscars. The competition between the contributions from different bifurcations to determine the moments of the averaged eigenfunction amplitude is analysed. We argue that there is a resulting universal hbar-scaling in the semiclassical asymptotics of these moments for irregular states in systems with a mixed phase-space dynamics. Finally, a number of these predictions are illustrated by numerical computations for a family of perturbed cat maps.Comment: 24 pages, 6 Postscript figures, corrected some typo

Use of modern educational technologies and standardization of control by the department of general dentistry of OMU IHU in order to improve the quality of training of dentists

In the implementation of the strategy of Ukraine's integration into the European Union, one of the directions of the higher educational establishments in general and higher medical educational institutions in particular is the introduction of a system of integrated licensed examinations with a university-independent assessment of knowledge according to state standards. The results of the licensed exam allow you to get an objective picture of the level of theoretical training of graduate students, and the integral exam Krok-2 is a progressive form in the work of a higher medical school. The authors cover aspects of improving the educational process at the Department of General Dentistry. The implemented methods of teaching allowed to combine theoretical training of students for the practical training of their practical skills; made more interesting and clear independent non-auditing work of students; gave teachers the ability to control the quality of this work. It allows to improve the quality of preparation of students-dentists both for final examinations, and for the further professional activity

Pseudosubluxación C2-C3: un hallazgo radiológico frecuente en la infancia

Objetivo: Mostrar un hallazgo radiológico fisiológico de la columna cervical infantil que tiende a ser malinterpretado como patológico: la pseudosubluxación C2-C3. Se presenta un caso de una niña de 14 meses de edad remitida a nuestro centro bajo sospecha de subluxación C2-C3. Se aporta una metodología para el diagnóstico diferencial entre pseudosubluxación C2-C3 y subluxación C2-C3 verdadera. Una anamnesis detallada así como una exploración clínica y radiográfica minuciosas, permiten establecer el diagnóstico en la mayoría de los casos. La normal movilidad en flexión de C2 sobre C3 en la columna cervical infantil puede ser tan pronunciada que llegue a confundirse con una lesión. La interpretación adecuada de las radiografías simples de la columna cervical en los niños requiere el conocimiento de las peculiaridades de este segmento en la edad pediátrica.Objective: To report on a physiological radiographic finding of the cervical spine in childhood that trends to be misjudged as pathologic: C2-C3 pseudosubluxation. We presented a girl, aged 14 months, who was remitted to our Center for clinical suspect of C2-C3 subluxation. A diagnostic methodology is offered to distinguish between C2-C3 pseudosubluxation and a true C2-C3 subluxation. A detailed anamnesis as well as a meticulous radiological and clinical exploration, allow to establish the right diagnosis in most cases, without any other complementary probe. The normal mobility of C2 on C3 in flexion could be so pronounced as to be mistaken for a pathological finding. The suitable radiographic interpretation of the cervical spine in children requires the knowledge of the peculiarities of this segment in the pediatric age