Exotic galilean symmetry and the Hall effect

The ``Laughlin'' picture of the Fractional Quantum Hall effect can be derived using the ``exotic'' model based on the two-fold centrally-extended planar Galilei group. When coupled to a planar magnetic field of critical strength determined by the extension parameters, the system becomes singular, and ``Faddeev-Jackiw'' reduction yields the ``Chern-Simons'' mechanics of Dunne, Jackiw, and Trugenberger. The reduced system moves according to the Hall law.Comment: Talk given by P. A. Horvathy at the Joint APCTP- Nankai Symposium. Tianjin (China), Oct.2001. To appear in the Proceedings, to be published by Int. Journ. Mod. Phys. B. 7 pages, LaTex, IJMPB format. no figure

Dirac Operator on a disk with global boundary conditions

We compute the functional determinant for a Dirac operator in the presence of an Abelian gauge field on a bidimensional disk, under global boundary conditions of the type introduced by Atiyah-Patodi-Singer. We also discuss the connection between our result and the index theorem.Comment: RevTeX, 11 pages. References adde

An alternative well-posedness property and static spacetimes with naked singularities

In the first part of this paper, we show that the Cauchy problem for wave propagation in some static spacetimes presenting a singular time-like boundary is well posed, if we only demand the waves to have finite energy, although no boundary condition is required. This feature does not come from essential self-adjointness, which is false in these cases, but from a different phenomenon that we call the alternative well-posedness property, whose origin is due to the degeneracy of the metric components near the boundary. Beyond these examples, in the second part, we characterize the type of degeneracy which leads to this phenomenon.Comment: 34 pages, 3 figures. Accepted for publication in Class. Quantum Gra

Implementation of the senior high school program in public schools in Pampanga, Philippines

Este estudio tiene por objeto describir y evaluar la aplicación de la enseñanza secundaria en determinadas escuelas para los años académicos 2016-2018. Concretamente, encontró respuestas sobre la descripción de las escuelas; la evaluación de las competencias pedagógicas de los profesores; la evaluación de los hábitos de trabajo, valores y habilidades de los estudiantes; los problemas encontrados, y las posibles contribuciones para mejorar el programa. Paralelamente se utilizó un método mixto específicamente convergente. Los resultados muestran que las escuelas seleccionadas ofrecen principalmente TVL, HUMSS y ABM. Tienen un promedio de 200 estudiantes o menos. La mayoría de los miembros de su facultad están con unidades de MA. Observaron las políticas del Departamento de Educación sobre admisión, retención y promoción. Las dimensiones de las competencias de enseñanza se consideran de efectivas a muy efectivas, mientras que los hábitos de trabajo, valores y habilidades de los estudiantes se evalúan como altamente desarrollados. Se identificaron problemas relacionados con la adecuación de los materiales de enseñanza, la falta de apoyo de los interesados, el rendimiento de los estudiantes y la necesidad de contar con profesores especializados. Por lo tanto, se recomienda mejorar las instalaciones escolares, contratar profesores para profesores especializados, fortalecer las asociaciones con la industria empresarial y capacitar a los profesores en las últimas tendencias de la enseñanza, así como en tecnología, para que los estudiantes sean competitivos a nivel mundial.This study is intended to describe and evaluate the implementation of high school in selected schools for the 2016-2018 academic years. Specifically, it found answers on the description of the schools; the evaluation of the pedagogical competencies of the teachers; the evaluation of the work habits, values, and skills of the students; the problems encountered, and the possible contributions to improve the program. A specifically convergent mixed method was used in parallel. The results show that the selected schools offer TVL, HUMSS, and ABM. They have an average of two hundred students or less. Most of their faculty members are with MA units. They observed the Department of Education's policies on admission, retention, and promotion. The dimensions of teaching competencies are considered effective to highly effective, while students' work habits, values, and skills are assessed as highly developed. Problems identified related to the adequacy of teaching materials, lack of stakeholder support, student performance, and the need for specialized teachers. Therefore, it is recommended to improve school facilities, hire teachers for specialized teachers, strengthen partnerships with the business industry, and train teachers in the latest teaching trends, as well as in technology, to make students globally competitive

The Landau problem and noncommutative quantum mechanics

The conditions under which noncommutative quantum mechanics and the Landau problem are equivalent theories is explored. If the potential in noncommutative quantum mechanics is chosen as $V= \Omega \aleph$ with $\aleph$ defined in the text, then for the value ${\tilde \theta} = 0.22 \times 10^{-11} cm^2$ (that measures the noncommutative effects of the space), the Landau problem and noncommutative quantum mechanics are equivalent theories in the lowest Landau level. For other systems one can find differents values for ${\tilde \theta}$ and, therefore, the possible bounds for ${\tilde \theta}$ should be searched in a physical independent scenario. This last fact could explain the differents bounds for $\tilde \theta$ found in the literature.Comment: This a rewritten and corrected version of our previous preprint hep-th/010517

Motion and Trajectories of Particles Around Three-Dimensional Black Holes

The motion of relativistic particles around three dimensional black holes following the Hamilton-Jacobi formalism is studied. It follows that the Hamilton-Jacobi equation can be separated and reduced to quadratures in analogy with the four dimensional case. It is shown that: a) particles are trapped by the black hole independently of their energy and angular momentum, b) matter alway falls to the centre of the black hole and cannot understake a motion with stables orbits as in four dimensions. For the extreme values of the angular momentum of the black hole, we were able to find exact solutions of the equations of motion and trajectories of a test particle.Comment: Plain TeX, 9pp, IPNO-TH 93/06, DFTUZ 93/0

Determinants of Dirac operators with local boundary conditions

We study functional determinants for Dirac operators on manifolds with boundary. We give, for local boundary conditions, an explicit formula relating these determinants to the corresponding Green functions. We finally apply this result to the case of a bidimensional disk under bag-like conditions.Comment: standard LaTeX, 24 pages. To appear in Jour. Math. Phy

Effects on Berry Shrinkage in Vitis vinifera. L cv. ‘Merlot’ From Changes in Canopy/Root Ratio: A Preliminary Approach

A trial was conducted to find a possible relationship between the canopy/root ratio and the incidence and severity of premature berry shrinkage, and to propose an alternative to avoid this phenomenon in ‘Merlot’ grapevines. The ratio was changed by cutting foliage at a certain height 15 days before véraison, and by delaying the removal of trunk shoots. Treatments were the control (T1), 50% foliage area of control (T2), 75% foliage area of control (T3), and delayed trunk shoot removal (T4). Foliage area and the canopy/root ratio were lower in the T2 and T3 treatments. T4 was ineffective in changing the parameters. The incidence of berry shrinkage was lower for the T2 and T3 treatments, with the percentage of affected plants dropping from the 52% of the control to 22.9% and 31.3% for T2 and T3 respectively, and from 52.4% of the affected bunches to 16.6% and 21.2% for the same treatments respectively. The percentage of affected bunches falling into the range of moderate to severe damage fell from the 24% of the control to 5.2% and 3.9% for T2 and T3 respectively. Therefore, it is possible to avoid the incidence and severity of berry shrinkage by decreasing the canopy/root ratio in ‘Merlot’ grapevines

Symmetry types of hyperelliptic Riemann surfaces

Let $X$ be a compact hyperelliptic Riemann surface which admits anti-analytic involutions (also called symmetries or real structures). For instance, a complex projective plane curve of genus two, defined by an equation with real coefficients, gives rise to such a surface, and complex conjugation is such a symmetry. In this memoir, the real structures $\tau$ of $X$ are classified up to isomorphism (i.e., up to conjugation). This is done as follows: the number of connected components of the set of fixed points of $\tau$ together with the connectedness or disconnectedness of the complementary set in $X$ classifies $\tau$ topologically; they determine the species of $\tau$, which only depends on the conjugacy class of $\tau$ (however, different conjugacy classes may have identical species). On these grounds, for a given genus $g\ge2$, the authors first give a list of all full groups of analytic and anti-analytic automorphisms of genus $g$ compact hyperelliptic Riemann surfaces. For every such group $G$, the authors compute polynomial equations for a surface $X$ having $G$ as full group and then find the number of conjugacy classes containing symmetries; they also compute a representative $\tau$ in every such class. Finally, they compute the species corresponding to such classes. This memoir is an exhaustive piece of work, going through a case-by-case analysis. The problem for general compact Riemann surfaces dates back to 1893, when {\it F. Klein} [Math. Ann. 42, 1--29 (1893)] first studied it. For zero genus, it is easy. For genus one, that is, for elliptic surfaces, it was solved by {\it N. Alling} ["Real elliptic curves" (1981)]. Partial results for hyperelliptic surfaces of genus two were obtained by {\it E. Bujalance} and {\it D. Singerman} [Proc. Lond. Math. Soc. 51, 501--519 (1985)]