Elementary Particles and Spin Representations

We emphasize that the group-theoretical considerations leading to SO(10) unification of electro-weak and strong matter field components naturally extend to space-time components, providing a truly unified description of all generation degrees of freedoms in terms of a single chiral spin representation of one of the groups SO(13,1), SO(9,5), SO(7,7) or SO(3,11). The realization of these groups as higher dimensional space-time symmetries produces unification of all fundamental fermions is a single space-time spinor.Comment: 4 page

On effects of regular S=1 dilution of S=1/2 antiferromagnetic Heisenberg chains by a quantum Monte Carlo simulation

The effects of regular S=1 dilution of S=1/2 isotropic antiferromagnetic chain are investigated by the quantum Monte Carlo loop/cluster algorithm. Our numerical results show that there are two kinds of ground-state phases which alternate with the variation of $S^1=1$ concentration. When the effective spin of a unit cell is half-integer, the ground state is ferrimagnetic with gapless energy spectrum and the magnetism becomes weaker with decreasing of the $S^1$ concentration $\rho = 1/M$. While it is integer, a non-magnetic ground state with gaped spectrum emerges and the gap gradually becomes narrowed as fitted by a relation of $\Delta \approx 1.25\sqrt{\rho}$.Comment: 6 pages, 9 figure

Huella de carbono de los sitemas de producci?n del centro universitario regional del norte (CURDN) de la Universidad del Tolima, Armero - Guayabal, Tolima Colombia

83 p. Recurso Electr?nicoEl cambio clim?tico es ocasionado por el aumento en las concentraciones de gases de efecto de invernadero. El objetivo de este estudio fue estimar la huella de carbono del Centro Universitario Regional del Norte (CURDN), Armero, Guayabal. La huella de carbono se estim? como la diferencia entre la fijaci?n de carbono en biomasa y las emisiones de gases de efecto invernadero. Se establecieron 44 parcelas temporales de muestreo en los diferentes usos del suelo donde se midi? todos los ?rboles con di?metro del tronco a la altura del pecho > 10 cm y plantas de cacao. Se emplearon modelos alom?tricos y factores de expansi?n de biomasa, la fracci?n de carbono (0,5) y se calcul? el CO2e. Se estim? la fijaci?n de los sistemas productivos en biomasa de le?osas perennes considerando el almacenamiento de carbono y la edad. Se indag?, mediante encuestas semi-estructuradas, las actividades de manejo en los sistemas productivos y del ?rea administrativa que emiten gases de efecto invernadero. La huella de carbono del CURDN fue positiva (1575,7 t CO2e/a?o), es decir, la fijaci?n es mayor que las emisiones de gases de efecto invernadero. Se encontr? que los sistemas de producci?n agr?colas y pecuarios son emisores netos de ?stos gases (1,1 y 2,8 t CO2e/ha/a?o, respectivamente); mientras que los sistemas forestales fijan netamente 14,0 t CO2e/ha/a?o. Los resultados muestran que el CURDN es carbono neutro y podr?a eventualmente vender cr?ditos de carbono, adicionalmente se muestra la importancia de los componentes le?osos como sumideros de carbono para la mitigaci?n del cambio clim?tico. Palabras clave: Cambio clim?tico, huella carbono, fijaci?n de carbono, emisi?n gases de efecto invernadero, modelos alometricosThe climate change is caused by the increase of greenhouse gases. The objective of this study was to estimate the carbon footprint in the Centro Universitario Regional del Norte (CURDN), Armero, Guayabal. The carbon footprint was estimated as the difference between carbon fixation in biomass and the emission of greenhouse gases. A total of 44 temporal sampling plots in the different land uses where all trees with diameter of trunk at the breast height > 10 cm and cacao plants. Alometric models and biomass expansion factors and the carbon fraction (0.5) were employed and CO2e was calculated. It was estimated the fixation of the productive systems in biomass of woody perennial plants considering carbon storage and age. It was consulted, throught semi-estructured interviews, the activity management in the productive systems and the administrative area that emit greenhouse gases. The carbon footprint of the CURDN was positive (1575.7 t CO2e/year), in other words, the fixation is higher tan emissions. It was found that agriculture and cattle productive systems are net emisors (1.1 and 2.8 t CO2e/ha/year, respectively); whereas the forestry systems anually fix 14.0 t CO2e/ha/year. The results show that CURDN is carbon neutral and it could sale carbon credits, additionally it is shown the importance of woody components as carbon sinks for climate change mitigation. Keywords: Climate change, carbon footprint, carbon fixation, emission of greenhouse gases, allometric models

Seis representaciones arquet?picas precolombinas (correspondencias con la narrativa hispanoamericana contempor?nea y creaci?n de minicuento)

175 p. Recurso Electr?nicoLa presente investigaci?n compila un corpus de representaciones arquet?picas a la luz de la teor?a sobre el inconsciente colectivo y los arquetipos planteados por Carl Gustav Jung. La configuraci?n de las representaciones fue realizada con mitos precolombinos, posterior a ello, a trav?s del m?todo de Gilbert Durand, denominado mitocr?tica, se comprob? la vigencia de las representaciones en cuentos de autores hispanoamericanos. As? mismo, se dise?? una unidad did?ctica para trasformar la ense?anza del mito en el grado noveno de la Instituci?n Educativa Alberto Castilla, con el fin de ampliar desde la teor?a de Mircea Eliade y de Carl Jung el concepto de mito, y el corpus de relatos le?dos por los estudiantes, para poder descubrir las convergencias arquet?picas, los atributos simb?licos y el car?cter sagrado que demuestran la relaci?n vigente entre mito y hombre. Finalmente, los estudiantes tuvieron la oportunidad de actualizar mitos, arquetipos y representaciones, mediante un proceso de escritura de minicuentos a trav?s del taller como espacio de aprendizaje, juego y creaci?n. Palabras Claves: Mito, Arquetipo, Mitocr?tica, Minicuento.The present investigation, compiles a corpus of representations archetypical in the light of theory about the collective unconscious and the archeotype raised by Carls Gustav Jung. The configuration of the representations were presented with pre-columbian myths, subsequently to it through the method of Gilbert Duran called mitochritic, was verified the validity of the representation in the stories of Hispanic -American authors. Likewise, a didactic unit was designed to transform the teaching of myth in the ninth grade of the educational institution Alberto Castilla, in order to expand from the theory of Mircea Eliade and of Carl Jung the concept of myth, and the corpus of stories read by the students, in order to discover the archetypal convergences, the symbolic attributes and the sacred character that demonstrates the current relationship between myth and man. Finally the students had the opportunity to update myths, archetypes and representations, through a process of writing mini-stories through the workshop as a space for learning, play and creation. Keywords: Myth, Archetype, Mitocritical, Mini-stories

A DMRG Study of Low-Energy Excitations and Low-Temperature Properties of Alternating Spin Systems

We use the density matrix renormalization group (DMRG) method to study the ground and low-lying excited states of three kinds of uniform and dimerized alternating spin chains. The DMRG procedure is also employed to obtain low-temperature thermodynamic properties of these systems. We consider a 2N site system with spins $s_1$ and $s_2$ alternating from site to site and interacting via a Heisenberg antiferromagnetic exchange. The three systems studied correspond to $(s_1 ,s_2 )$ being equal to $(1,1/2),(3/2,1/2)$ and $(3/2,1)$; all of them have very similar properties. The ground state is found to be ferrimagnetic with total spin $s_G =N(s_1 - s_2)$. We find that there is a gapless excitation to a state with spin $s_G -1$, and a gapped excitation to a state with spin $s_G +1$. Surprisingly, the correlation length in the ground state is found to be very small for this gapless system. The DMRG analysis shows that the chain is susceptible to a conditional spin-Peierls instability. Furthermore, our studies of the magnetization, magnetic susceptibility $\chi$ and specific heat show strong magnetic-field dependences. The product $\chi T$ shows a minimum as a function of temperature T at low magnetic fields; the minimum vanishes at high magnetic fields. This low-field behavior is in agreement with earlier experimental observations. The specific heat shows a maximum as a function of temperature, and the height of the maximum increases sharply at high magnetic fields. Although all the three systems show qualitatively similar behavior, there are some notable quantitative differences between the systems in which the site spin difference, $|s_1 - s_2|$, is large and small respectively.Comment: 16 LaTeX pages, 13 postscript figure

El E- Portafolio como estrategia metodol?gica de evaluaci?n del ?rea de ciencias sociales en b?sica secundaria. Una experiencia educativa en el sector rural en la Instituci?n Educativa T?cnica Camacho Angarita, El Lim?n ? Chaparral

80 P?ginasEl presente trabajo tiene como objeto de estudio proponer el e-portafolio como estrategia metodol?gica de evaluaci?n del ?rea de Ciencias Sociales en los estudiantes del grado noveno de la Instituci?n Educativa T?cnica Camacho Angarita ubicada en el sector rural, corregimiento el Lim?n ? Chaparral, con el fin de promover en el educando una mayor capacidad de reflexi?n sobre su aprendizaje. Esta propuesta surge con la utilizaci?n inicialmente de recursos audiovisuales hasta el uso de las TIC en el ?rea de Ciencias Sociales, caracterizando al docente con un papel orientador m?s que transmisor, a la clase con un lenguaje audiovisual interactivo de im?genes y conceptos que favorecen los procesos de comunicaci?n y socializaci?n entre el docente y los estudiantes. La evaluaci?n en esta experiencia ocupa un lugar central en el proceso educativo, al ser tenida en cuenta en cada momento de la construcci?n del e-portafolio del estudiante, considerando de igual manera que en la actualidad los procesos educativos requieren en el aula curr?culos flexibles en los que el estudiante cuente con espacios no s?lo para aprender, sino tambi?n para reaprender al tener la oportunidad de reestructurar sus producciones acad?micas. El trabajo comprende la sistematizaci?n de una experiencia educativa: antecedentes, caracterizaci?n, etapas para el desarrollo e implicaciones del e-portafolio del estudiante, de igual manera se resaltan las dificultades, obst?culos, alcances y posibles reformas consider?ndose categor?as desde lo rural, pedag?gico, did?ctico, evaluativo y social. Finalmente, se pretende motivar a los docentes para que se integren a los procesos educativos de manera reflexiva y consciente dentro de formas educativas y en especial evaluativas no tradicionales. Palabras claves: TIC, educaci?n, sector rural, evaluaci?n, portafolio educativo, e-portafolio.ABSTRACT. The present work aims to propose the e-portfolio as an assessment methodological strategy of Social Sciences in ninth grade students at the Technical Educational Institution Camacho Angarita located in the rural areas of the district El Lim?n - Chaparral, with the purpose of promoting in students a greater ability to reflect on their own learning. This proposal arises initially with the use of audiovisual resources until the use of ICT in the area of Social Sciences, characterizing the teacher with a guiding role rather than transmitter, adding to the class an interactive audiovisual language of images and concepts that promote processes of communication and socialization between teacher and students. The evaluation of this experience is central to the educational process, when taken into account all the time during the construction of the e-portfolio for the student, also considering that nowadays the educational processes in the classroom require flexible curricula through which the student has space not only to learn, but also to relearn by having the opportunity to restructure their academic productions. This work includes the systematization of an educational experience: backgrounds, characterization, development stages and implications of the student portfolio; likewise It is highlighted the difficulties, obstacles, achievements and possible reforms considering some categories as the rural, pedagogical, didactic, evaluative and social. Finally, it is intended to motivate teachers to be integrated into educational processes in a thoughtful and conscious way in educational forms and more especially in non-traditional evaluative forms.La Facultad de Ciencias de la Educaci?n de la Universidad del Tolima, el director, codirector y el jurado calificador, no son responsables de los conceptos ni de las ideas expuestas por los autores del presente trabajo. Art?culo 16, Acuerdo 032 de 1976 y Art?culo 29, Acuerdo 064 de 1991, Concejo Acad?mico de la Universidad del Tolima.INTRODUCCI?N 13 1. JUSTIFICACI?N 15 2. OBJETIVOS 17 2.1 OBJETIVO GENERAL 17 2.2 OBJETIVOS ESPEC?FICOS 17 3. ANTECEDENTES 18 4. MARCO CONCEPTUAL 20 4.1 GENERALIDADES Y EVOLUCI?N DE LA EDUCACI?N EN LAS INSTITUCIONES EDUCATIVAS DESDE EL CONTEXTO RURAL 20 4.2 EDUCACI?N DEL ?REA DE CIENCIAS SOCIALES EN B?SICA SECUNDARIA 26 4.3 INTEGRACI?N DE LAS TIC AL PROCESO ENSE?ANZA-APRENDIZAJE 28 4.4 GENERALIDADES DE LA EVALUACI?N EDUCATIVA 34 4.5 LA EVALUACI?N DEL APRENDIZAJE EN EL ?REA DE CIENCIAS SOCIALES EN B?SICA SECUNDARIA 39 4.6 EL PORTAFOLIO EDUCATIVO 42 4.7 EL E-PORTAFOLIO COMO ESTRATEGIA METODOL?GICA PARA LA EVALUACI?N DE LOS ESTUDIANTES 46 5. METODOLOG?A DEL TRABAJO 51 6. DESCRIPCI?N DE LA EXPERIENCIA CON EL PORTAFOLIO EDUCATIVO 52 6.1 RECUENTO HIST?RICO DE LA INCORPORACI?N DE LAS TIC Y EL PORTAFOLIO EDUCATIVO EN LA INSTITUCI?N EDUCATIVA T?CNICA CAMACHO ANGARITA 52 6.2 RECUENTO HIST?RICO DEL DESORRALLO DEL PORTAFOLIO EDUCATIVO Y DEL USO DEL E-PORTAFOLIO EN EL ?REA DE CIENCIAS SOCIALES 53 6.3 CARACTER?STICAS DEL PORTAFOLIO EDUCATIVO. 55 6.4 COMPONENTES DEL PORTAFOLIO EDUCATIVO 58 6.5 EL E-PORTAFOLIO DEL ESTUDIANTE COMO ESTRATEGIA DE EVALUACI?N 61 6.5.1 Alcances del e-portafolio del estudiante en la evaluaci?n 62 6.5.2 Uso pedag?gico del software educativo Edraw Max. 65 6.5.3 Implicaciones del portafolio educativo y del e-portafolio del estudiante. 66 7. CONCLUSIONES 71 REFERENCIAS 73 ANEXOS 7

Estudio de propiedades estructurales y magn?ticas de aleaciones de tierras raras y metales de transici?n

101 p. Recurso Electr?nicoEn el presente trabajo se reporta el estudio de las propiedades estructurales y magn?ticas de polvos de Gd0.257-xTbxFe0.743 con x = 0, 0.1285, y 0.257, preparadas por Aleamiento Mec?nico (MA) en atm?sfera de arg?n durante 48 y 72 horas mediante un molino planetario de alta energ?a. La caracterizaci?n estructural se realiz? por medio de Difractometr?a de rayos X (XRD), para la caracterizaci?n magn?tica se utiliz? la espectroscopia M?ssbauer y ciclos de hist?resis de las muestras utilizando un magnet?metro de muestra vibrante VSM (Vibration Sample Magnetometry) de un sistema PPMS (Physical Property Measurement System). La fase ?-Fe se presenta, en difracci?n de rayos-x, para todo x, mediante un pico caracter?stico cuya intensidad permanece ligeramente constante; sin embargo un aumento de su ancho al sustituir el Gd por el Tb se observa, que se correlaciona con una disminuci?n del tama?o de cristalito de la fase ?-Fe. Los resultados de los espectros M?ssbauer a temperatura ambiente indican que el sistema presenta un comportamiento ferromagn?tico para todas las composiciones y los ciclos de hist?resis revelan que presenta un comportamiento magn?ticamente semiduro, que es una propiedad importante de materias prima para memorias magneto-?pticas. Palabras Clave: Aleamiento mec?nico, Difractometr?a de rayos X, Espectroscopia M?ssbauer, Sistema GdTbFe.In present work the study of the structural and magnetic properties of powders of composition Gd0.257-xTbxFe0.743 with x = 0, 0.1285, 0.257, prepared by Mechanical Alloying (MA) in argon atmosphere, during 48 and 72 hours, using a high energy planetary ball mill is reported. The structural characterization was performed by means of X-ray diffractometry (XRD); and for the magnetic characterization M?ssbauer spectroscopy was used, the hysteresis cycles of the samples were obtained using the VSM (vibration sample magnetometry) of a PPMS (Physical Property Measurement System). The ?-Fe phase is presented, in the RDX patterns, for all x, by a characteristic peak whose intensity remains slightly constant, however, an increase of its width is obtained when the Gd is replaced by the Tb, which is associated to a decrease in the crystallite size of the ?-Fe phase. The M?ssbauer results at room temperature indicate that the system exhibits a ferromagnetic behavior for all compositions, and the hysteresis cycles show that it exhibits a magnetically semi-hard behavior, which is an important characteristic for raw material for magneto-optical memory. Keywords: Mechanical alloying, X-ray diffraction, M?ssbauer spectroscopy, GdTbFe System

Inflation in minimal left-right symmetric model with spontaneous D-parity breaking

We present a simplest inflationary scenario in the minimal left-right symmetric model with spontaneous D-parity breaking, which is a well motivated particle physics model for neutrino masses. This leads us to connect the observed anisotropies in the cosmic microwave background to the sub-eV neutrino masses. The baryon asymmetry via the leptogenesis route is also discussed briefly.Comment: (v1) 4 pages, 1 figure; (v2) typos corrected; (v3) title and abstract changed, numerical estimates given, minor changes; (v4) 5 pages, relations between the neutrino masses and the CMB fluctuations become more explicit, miscellaneous changes, to appear in Physical Review

Quantum cobwebs: Universal entangling of quantum states

Entangling an unknown qubit with one type of reference state is generally impossible. However, entangling an unknown qubit with two types of reference states is possible. To achieve this, we introduce a new class of states called zero sum amplitude (ZSA) multipartite, pure entangled states for qubits and study their salient features. Using shared-ZSA state, local operation and classical communication we give a protocol for creating multipartite entangled states of an unknown quantum state with two types of reference states at remote places. This provides a way of encoding an unknown pure qubit state into a multiqubit entangled state. We quantify the amount of classical and quantum resources required to create universal entangled states. This is possibly a strongest form of quantum bit hiding with multiparties.Comment: Invited talk in II Winter Institute on FQTQO: Quantum Information Processing, held at S. N. Bose Center for Basic Science, Kolkata, during Jan 2-11, 2002. (To appear in Pramana-J. of Physics, 2002.