Reflexiones sobre la enseñanza de la física universitaria

In spite of the scientific and technological development and a worldwide increment in the number of university students, it is evident a decrease in the number of students of physics in this level. This work brings out some features of the university education, particularly the teaching of the firsts courses. At the same time it is stated that a poor didactic knowledge, a rutinary teaching, that is not participative from the part of the teachers can be linked to a growing loss of interest from the part of the students. Finally the authors give some trends to make a deep study of this problem

Thermodynamics of the classical spin-ice model with nearest neighbour interactions using the Wang-Landau algorithm

In this article we study the classical nearest-neighbour spin-ice model (nnSI) by means of Monte Carlo simulations, using the Wang-Landau algorithm. The nnSI describes several of the salient features of the spin-ice materials. Despite its simplicity it exhibits a remarkably rich behaviour. The model has been studied using a variety of techniques, thus it serves as an ideal benchmark to test the capabilities of the Wang Landau algorithm in magnetically frustrated systems. We study in detail the residual entropy of the nnSI and, by introducing an applied magnetic field in two different crystallographic directions ([111] and [100],) we explore the physics of the kagome-ice phase, the transition to full polarisation, and the three dimensional Kasteleyn transition. In the latter case, we discuss how additional constraints can be added to the Hamiltonian, by taking into account a selective choice of states in the partition function and, then, show how this choice leads to the realization of the ideal Kasteleyn transition in the system.Comment: 9 pages, 9 figure

Facies analysis and stratigraphic assignment of Middle Jurassic unnamed fluvial deposits in the Southern Mendoza Neuquén Basin

Se realizaron estudios sedimentológico-estratigráficos en los depósitos fluviales innominados del Jurásico Medio de la Cuenca Neuquina surmendocina, que afloran en el anticlinal de Malargüe y Bardas Blancas. En el primero de ellos se reconocieron facies de sistemas fluviales entrelazados gravo-arenosos que se apilan en tres secuencias depositacionales mostrando un decrecimiento paulatino en el espacio de acomodación, en tanto que en el segundo se reconocieron facies de sistemas fluviales anastomosados que se agrupan en dos secuencias depositacionales con un incremento progresivo del espacio de acomodación. En el anticlinal de Malargüe las relaciones estratigráficas y el patrón de apilamiento sugiere la asignación de estos depósitos al Bajociano tardío-Bathoniano y su correlación con la Formación Lajas, por lo que se propone la denominación de Formación Puesto Pacheco nov. nom., con su estratotipo en la sección del arroyo Loncoche. En el área de Bardas Blancas la presencia de clastos de calizas y fragmentos de ostras en la base de la unidad permitiría establecer que los depósitos fluviales se habrían depositado con posterioridad a la discordancia Intracaloviana. En este sector se le asigna una edad Caloviana media - tardía y se los asigna a la Formación Lotena.Stratigraphic-sedimentological studies were performed on Middle Jurassic unnamed fluvial deposits of the Southern Mendoza Neuquén Basin, cropping out in the Malargüe anticline and Bardas Blancas. In the first area we recognized braided fluvial systems facies stacked in three depositional sequences showing a gradual decrease in the accommodation space, whereas in the second we recognized anastomosing fluvial systems facies grouped into two depositional sequences with a progressive increase in the accommodation space. Stratigraphic relationships and stacking pattern in the Malargüe anticline suggests the assignment of this unit to the late Bajocian-Bathonian and its correlation with the Lajas Formation, so the name of Puesto Pacheco Formation nov. nom. is proposed, with its stratotype in the Loncoche creek section. In the Bardas Blancas area the presence of limestone clasts and oysters fragments at the base of the unit, would establish that unnamed fluvial deposits would have been deposited after the Intracallovian unconformity. In this area it is given a middle-late Callovian age and the assignment to the Lotena Formation.Fil: Kietzmann, Diego Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos; ArgentinaFil: Palma, Ricardo Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos; ArgentinaFil: Ferreyra, Teresita M. A.. YPF - Tecnología; Argentin

Proposiciones de Euclides: problema-demostración desde una perspectiva antropológica

Se realiza este trabajo en el marco de una investigación acerca de la Resolución de Problemas como herramienta de aprendizaje de la matemática. Proclo, matemático griego, en su Comentario al libro primero de los Elementos de Euclides, dice que a pesar de que Euclides indica la diferencia entre problema y teorema con las palabras “lo que hay que hacer” o “lo que hay que mostrar”, respectivamente, las proposiciones de los Elementos que son problemas contienen demostraciones que fundamentan y justifican su resolución y no son para mostrar la naturaleza de lo que se ha investigado. En este trabajo se analizan desde una perspectiva antropológica dos de las proposiciones de Euclides para determinar la conveniencia o no de su presentación a los alumnos del Profesorado en Matemática

Mutual information and sensitivity analysis for feature selection in customer targeting: a comparative study

WOS:000454945400004Feature selection is a highly relevant task in any data-driven knowledge discovery project. The present research focuses on analysing the advantages and disadvantages of using mutual information (MI) and data-based sensitivity analysis (DSA) for feature selection in classification problems, by applying both to a bank telemarketing case. A logistic regression model is built on the tuned set of features identified by each of the two techniques as the most influencing set of features on the success of a telemarketing contact, in a total of 13 features for MI and 9 for DSA. The latter performs better for lower values of false positives while the former is slightly better for a higher false-positive ratio. Thus, MI becomes a better choice if the intention is reducing slightly the cost of contacts without risking losing a high number of successes. However, DSA achieved good prediction results with less features.info:eu-repo/semantics/acceptedVersio

Solving an open problem about the G-Drazin partial order

[EN] G-Drazin inverses and the G-Drazin partial order for square matrices have been both recently introduced by Wang and Liu. They proved the following implication: If A is below B under the G-Drazin partial order, then any G-Drazin inverse of B is also a G-Drazin inverse of A. However, this necessary condition could not be stated as a characterization and the validity (or not) of the converse implication was posed as an open problem. In this paper, this problem is completely solved. It is obtained that the converse, in general, is false, and a form to construct counterexamples is provided. It is also proved that the converse holds under an additional condition (which is also necessary) as well as for some special cases of matrices.Partially supported by Universidad Nacional de Río Cuarto (Grant PPI 18/C472), CONICET (Grant PIP 112-201501-00433CO), and by ANPCyT (Grant PICT 2018-03492) Partially supported by Universidad Nacional de La Pampa, Facultad de Ingeniería (Grant Resol. Nro. 155/14) Partially supported by Ministerio de Economía, Industria y Competitividad of Spain (Grant Red de Excelencia MTM2017-90682-REDT), and by Universidad Nacional del Sur of Argentina (Grant 24/L108)Ferreyra, DE.; Lattanzi, M.; Levis, FE.; Thome, N. (2020). Solving an open problem about the G-Drazin partial order. The Electronic Journal of Linear Algebra. 36:55-66. http://hdl.handle.net/10251/161871S55663

Estabilidade de agregados em solos sódicos e salino-sódicos.

bitstream/item/36226/1/Estabilidade-de-Agregados.pd

Catatonia en la población infantojuvenil

La catatonia es un síndrome neuropsiquiátrico descrito en 1874 por el Dr. Karl Kahlbaum. Se caracteriza por presentar mutismo, estupor, catalepsia, estereotipias, negativismo y ecofenómenos, entre otros. Si bien se encuentra bien definido en adultos, existe poca información referida a su presentación en población infantil. En el presente artículo se revisarán diferentes aspectos de la presentación clínica y del abordaje terapéutico de este síndrome.Catatonia is a neuropsychiatric syndrome described by Karl Kahlbaum in 1874. It is characterized by mutism, stupor, catalepsy, stereotypes, negativism and ecophenomena, among others. Although it is well described in adults, there is little information regarding its presentation in children. In this article different aspects of the clinical presentation and therapeutic approach of this syndrome will be reviewed