The role of the disorder range and electronic energy in the graphene nanoribbons perfect transmission

Numerical calculations based on the recursive Green's functions method in the tight-binding approximation are performed to calculate the dimensionless conductance $g$ in disordered graphene nanoribbons with Gaussian scatterers. The influence of the transition from short- to long-ranged disorder on $g$ is studied as well as its effects on the formation of a perfectly conducting channel. We also investigate the dependence of electronic energy on the perfectly conducting channel. We propose and calculate a backscattering estimative in order to establish the connection between the perfectly conducting channel (with $g=1$) and the amount of intervalley scattering.Comment: 7 pages, 9 figures. To be published on Phys. Rev.

Cotidiano de trabajo y formación de educadores sociales: la relación con educandos en centros educativos asistenciales

In Porto Alegre (Brazil), public education supported by the welfare system, in most cases, plays its role in very poor neighborhoods. The population of these communities, especially children and adolescents, has strong references in the work of social educators, not only pedagogical, but affective and socio-symbolic references, in its daily practice. As such, this report presents the results of research with educators who coordinate a welfare system-supported educational center in the community of Lomba do Pinheiro: The Child and Adolescent Support Center (CPCA). Examining the question «How does the formal education of the educators influence the educational practice implemented with the students?», the work has been taken from an action research perspective supported by observation techniques, relationship mapping and interviews, with the goal being to know the life histories of the people involved, to characterize the work context built within the organization and, from that point, to reflect on the relationships established with the students. The inferences thus derived point out that educators, on the one hand, establish relationships strongly guided by «the protection» of the students and, on the other hand, stimulate practices which are hardly emancipatory in nature and are quite hierarchal relative to the community where they perform their work. In this work, the research was oriented to question the pedagogical references of the educators, as practices derived from their self-eco-organization, to stimulate them to establish new socio-educational relationships with the objective of creating (self) shaping activities in the work of educating

Itinerários em periferias e redes no entorno escolar: diálogos com moradoras idosas da Restinga/Porto Alegre

This study problematizes the networks of elderly women’s biographical itineraries, in Restinga neighborhood, Porto Alegre/Brazil, by analyzing articulations vis-à-vis the school experiences. For such, this study relies on contributions from Martuccelli and Requena Santos concerning the delimitation of supports and social networks. After an inventory of the social conditions and of the relational arrangements managed by these women, this study highlights the links with the political, religious and musical-carnival arenas, regarded as social spaces of itinerary differentiation. The place of the school is interpreted from the spaces of the possibilities produced, so that they can indicate different meanings for these experiences in the institution, in relation to political actions or labor activities.El artículo problematiza las redes de acción en los itinerarios biográficos de moradoras mayores del barrio Restinga, en Porto Alegre/Brasil, analizando las articulaciones com experiencias escolares. Considera, así, las contribuciones de Martuccelli y de Requena Santos en la delimitación de soportes y redes sociales. Tras un inventario de las condiciones sociales y de los conjuntos relacionales agenciados por las estas mujeres, el texto destaca los lazos con las arenas política, religiosa y musicalcarnavalesca como espacios sociales de diferenciación de los recurridos. El lugar de la escuela es interpretado, adelante, desde los espacios de posibles construidos y hacia sentidos diversos para las vivencias en la institución, en la acción política o en la temporalidad distinta de la laboral.O artigo problematiza as redes de ação que compunham os itinerários biográficos de moradoras idosas do bairro Restinga, em Porto Alegre/RS, analisando as articulações com experiências escolares. Para tanto, apoia-se em contribuições de Martuccelli e de Requena Santos na delimitação de suportes e redes sociais. Após um inventário das condições sociais e dos arranjos relacionais agenciados pelas mulheres, o texto destaca os laços com as arenas política, religiosa e musical-carnavalesca, transversalizadas pela pertença territorial, como espaços sociais de diferenciação dos percursos. O lugar da escola é interpretado, então, a partir do espaço de possíveis construído, de modo a indiciar sentidos diversos para as vivências na instituição, na ação política ou na temporalidade distinta da laboral

Youth itineraries, individuation, and reflexivities: approaches to social participation in low-income metropolitan neighborhoods

En este artículo se presenta un análisis de itinerarios de individuación, en atención a las formas de participación y reflexividad de personas jóvenes que viven en barrios populares de tres áreas metropolitanas: Buenos Aires/Argentina, Porto Alegre/Brasil y Santiago/Chile. Para ello, se articulan resultados de diferentes estudios empíricos desarrollados entre 2013 y 2019, con herramientas conceptuales de la sociología del individuo de Danilo Martuccelli, especialmente las nociones de pruebas, soportes y texturas sociales. En primer lugar, se abordan los referentes teóricos utilizados para el despliegue del problema y las estrategias metodológicas utilizadas para la construcción y el análisis de las narrativas juveniles. Posteriormente, se realiza la interpretación del corpus de datos en torno a dos ejes centrales: a) territorios, actores e intermundos populares; b) jóvenes, participación social y reflexividades. Las personas jóvenes enfrentan, en diversos territorios populares, una pluralidad de coerciones materiales y simbólicas. Sin embargo, allí también traman espacios colectivos donde establecen identificaciones personales y grupales, cuando descubren o generan propuestas deportivas, artístico-políticas y educativas. En estas, producen vínculos intergeneracionales, recuperan saberes ancestrales y construyen marcos referenciales y reflexivos, volviendo la territorialidad un soporte y un signo de reconocimiento. En este sentido, el estudio de las narrativas juveniles constituye una herramienta privilegiada para el análisis de las agencias y las individualidades populares latinoamericanas.This study analyzes individuation itineraries by considering the forms of participation and reflexivity of young people who live in low-income neighborhoods in three metropolitan areas: Buenos Aires/Argentina, Porto Alegre/Brazil, and Santiago/Chile. For this, this study articulated the results of several empirical studies conducted from 2013 to 2019 with the conceptual tools in Danilo Martuccelli’s sociology of the individual, especially its notions of tests, supports, and social textures. This research first addresses theoretical frameworks to implement its problem and methodological strategies to build and analyze youth’s narratives. Then, it interpreted its data corpus around two central axes: a) low-income territories, actors, and interworlds and b) young people, social participation, and reflexivities. Young people face a plurality of material and symbolic coercions in several low-income territories. However, these territories also create collective spaces in which youths establish personal and group identifications as they discover or generate sports, artistic-political, and educational proposals, which create intergenerational bonds, recover ancestral knowledge, and build referential and reflective landmarks, transforming territorialities into supports and a sign of recognition. Thus, studying youth narratives offers a privileged tool to analyze Latin American low-income agencies and individualities