Juan Valenzuela - Academia.edu (original) (raw)

Papers by Juan Valenzuela

Este documento indica la importancia de la descentralización para mejorar la eficiencia del gasto... more Este documento indica la importancia de la descentralización para mejorar la eficiencia del gasto públicos y alcanzar el potencial de desarrollo de las regiones y municipios en Chile.

espanolResumen: El objetivo de este articulo es describir la magnitud, los niveles de recurrencia... more espanolResumen: El objetivo de este articulo es describir la magnitud, los niveles de recurrencia y las caracteristicas de las practicas de segregacion o agrupamiento por habilidad que ocurren en el sistema escolar chileno. Mediante analisis cuantitativos, se identificaron tres tipos de agrupamiento: a) al inicio del ciclo escolar, b) el reordenamiento de estudiantes y c) la distribucion no aleatoria de alumnos nuevos. Los resultados sugieren que el agrupamiento por habilidad es mas frecuente durante los ultimos anos de la educacion obligatoria, especialmente en el primer y tercer grados de ensenanza media o secundaria alta. Asimismo, el agrupamiento por habilidad es mas frecuente entre escuelas mas vulnerables y de mayor tamano. EnglishAbstract: The objective of this article is to describe the magnitude, the levels of recurrence, and the characteristics of the practices of segregation or grouping by ability that occur in the Chilean school system. Through quantitative analysis, thr...

REICE. Revista Iberoamericana sobre Calidad, Eficacia y Cambio en Educación, 2020

Si bien las políticas educativas y la investigación en educación han abordado la segregación entr... more Si bien las políticas educativas y la investigación en educación han abordado la segregación entre escuelas, las formas menos visibles de segregación y exclusión dentro de la escuela apenas se han estudiado. El objetivo de este estudio fue caracterizar y analizar la ocurrencia y concurrencia de dos tipos de prácticas: punitivas y de ordenamiento por habilidades. Se utilizó las bases de datos del sistema de información general de estudiantes de los años 2003 al 2018 para identificar prácticas de ordenamiento académico, y los cuestionarios que acompañan la prueba SIMCE del año 2018 para analizar las prácticas punitivas reportadas por estudiantes de 6° (N = 224.274) y 10° grado (N = 202.282) y a padres de estudiantes de 4° grado (N = 214.211), 6° grado (N = 204.894) y 10° grado (N = 171.596). Los resultados muestran que los estudiantes de sexo masculino y en condición de pobreza reciben más prácticas punitivas, y que el ordenamiento académico es utilizado ampliamente en las escuelas ch...

Learning and Individual Differences, 2016

This paper analyzes the segregation within schools in Chile, looking at the related institutional... more This paper analyzes the segregation within schools in Chile, looking at the related institutional factors and the effect that this process has on students' academic performance. To analyze the relationship between institutional factors and within-school segregation, it uses a logistic regression, controlling for a set of school characteristics. This analysis finds that within-school segregation is related to institutional factors such as school size and the characteristics of their students. To determine the effects of within-school segregation on academic performance, a multilevel regression model is used, organized in three levels: school, classroom and student. The results show that within-school segregation has negative consequences on educational quality, efficiency and equity, since internal segregation reduces the average educational outcomes of the schools and mostly affects students of middle groups within the school in both academic achievement and socioeconomic terms.

Serie Política Fiscal 101, CEPAL/GTZ, 1997

SIDALC - Servicio de Informacion y Documentacion Agropecuaria de las Americas.

Revista Iberoamericana de Educación, 2008

En el presente artículo pretendemos realizar un recorrido por la historia reciente de las polític... more En el presente artículo pretendemos realizar un recorrido por la historia reciente de las políticas de educación en Chile, centrándonos principalmente en los elementos de continuidad y ruptura que han sido característicos de este proceso. La herencia del gobierno militar no solo ha dejado su huella en la conciencia colectiva de un pueblo, sino también en la continuidad de un modelo macroeconómico, sustentado en los principios del libre mercado, lo que ha debilitado sistemáticamente la influencia del Estado en temas tales como previsión social, salud y educación. La privatización de la educación en Chile se ha constituido en uno de los elementos clave que caracterizan nuestro sistema educativo, y ha acrecentado la brecha existente entre la educación a la que accede la población con mejores ingresos y aquella que reciben los sectores más vulnerables. Con el retorno a la democracia se ha puesto énfasis en la necesidad de contar con un sistema educativo capaz de asegurar calidad y equid...

Agriculture, 2021

We tested an efficient, easily and economically manufactured wind-transported particle collector ... more We tested an efficient, easily and economically manufactured wind-transported particle collector of our own design, called a multidirectional trap (MDt), on fine-tilled Anthrosols. Results from the logs of nine vaned masts, each with four MDt collectors at different heights, showed a clear predominance of northeast and south winds. After analyzing sediment transport rates and their balance, we found that sediments from the south were being deposited rather than lost. A large amount of phyllosilicates, which are highly adhesive sediments, and therefore, increase aggregation, decreasing erodibility, were captured in the upper traps. Moreover, they are rich in calcium carbonate, mainly calcite, which is a powerful aggregate, and therefore, also decreases their wind erodibility. Sediments from the northeast, however, with almost double the total mass transport, contained the largest amount of captured quartz, promoting abrasion and increasing soil erodibility. Nevertheless, large amount...

Antioxidants, 2021

Cucurbitaceae is one of the most economically important plant families, and includes some worldwi... more Cucurbitaceae is one of the most economically important plant families, and includes some worldwide cultivated species like cucumber, melons, and squashes, and some regionally cultivated and feral species that contribute to the human diet. For centuries, cucurbits have been appreciated because of their nutritional value and, in traditional medicine, because of their ability to alleviate certain ailments. Several studies have demonstrated the remarkable contents of valuable compounds in cucurbits, including antioxidants such as polyphenols, flavonoids, and carotenoids, but also tannins and terpenoids, which are abundant. This antioxidant power is beneficial for human health, but also in facing plant diseases and abiotic stresses. This review brings together data on the antioxidant properties of cucurbit species, addressing the genetic and pre- and postharvest factors that regulate the antioxidant content in different plant organs. Environmental conditions, management, storage, and pr...

Agriculture, 2020

Zucchini is a vegetable fruit that is very susceptible to postharvest chilling injury, and fruit ... more Zucchini is a vegetable fruit that is very susceptible to postharvest chilling injury, and fruit ethylene production is correlated with chilling injury sensitivity, such that the more tolerant the cultivar, the lower is its ethylene production. It is expected that zucchini fruit with reduced sensitivity to ethylene would have a higher chilling injury tolerance. In this study, we compared the postharvest fruit quality of wild type and ethylene-insensitive mutant etr2b, in which a mutation was identified in the coding region of the ethylene receptor gene CpETR2B. Flowers from homozygous WT (wt/wt), mutant plants in homozygous (etr2b/etr2b) and heterozygous (wt/etr2b) were hand-pollinated, and all fruits were harvested with the same length, at about 8 days after pollination. After harvesting, fruit of each genotype was randomly divided in 3 batches of 12 fruits each (four replications with three fruits each), and then stored at 4 °C and 95% RH. At 0, 7, and 14 days after cold storage, ...

Revista de Ciencias Sociales, 2012

La gestión de los centros educativos es uno de los elementos relevantes a la hora de explicar la ... more La gestión de los centros educativos es uno de los elementos relevantes a la hora de explicar la mejora en la calidad y la equidad en la educación. En Chile se ha puesto atención a una serie de variables tales como liderazgo, gestión curricular, gestión de recursos, convivencia escolar que incidirían en el logro de resultados de aprendizaje de los estudiantes. A partir del año 2009, los Planes de Mejoramiento Educativo (PME) se propusieron como la principal estrategia para el logro de un aprendizaje continuo en cada una de estas variables. El objetivo del artículo es comprender las prácticas de liderazgo y aprendizaje organizacional que se dan durante el proceso de elaboración e implementación de dichos planes. Se utilizó una metodología cualitativa de tipo descriptiva e inductiva basada en el método hermenéutico. 6 Escuelas Básicas y 1 Liceo de Enseñanza Básica y Media pertenecientes a una Comuna Rural participaron en este estudio. El diseño es longitudinal utilizando entrevistas a...

Journal of Small Business & Entrepreneurship, 2020

Despite its widespread occurrence, the topic of failure is barely addressed in entrepreneurship e... more Despite its widespread occurrence, the topic of failure is barely addressed in entrepreneurship education. Consequently, students are given an incomplete and unrealistic picture of the complexity of being entrepreneurs. This study explores the pedagogical potential of introducing vicarious learning about failure in educational programs rather than focusing solely on starting, growing and success. Taking a qualitative approach, this study examined students' reflective reports written after an interview with an entrepreneur on their experience of failure. Using concepts emerging from these reports and theoretical constructs, it was established whether and how students drew lessons and reflections from the failure stories. The findings show that interviewing and reflecting about the experiences of entrepreneurs allow for vicarious learning from failure, yet without students having to experience it themselves. The lessons learned and the reflections feed each other in a continuous loop. Students recognized that entrepreneurship involves trial and error instead of one straight road. Important lessons include the importance of adaptable behavior, access to key resources, insights in business development and the benefits of networking. Hence, this article contributes to the pedagogy of entrepreneurial education and provides initial suggestions for educators to introduce vicarious learning about failure as a topic in their programs. RÉSUMÉ Malgr e sa fr equence elev ee, le sujet de l' echec est a peine abord e dans l'enseignement de l'entrepreneuriat. En cons equence, il est communiqu e aux etudiants une image incompl ete et irr ealiste de la complexit e d'être un entrepreneur. Cette etude explore le potentiel p edagogique de l'apprentissage par procuration sur l' echec dans les programmes educatifs, plutôt qu'une focalisation seulement sur le d emarrage, la croissance et la r eussite. En adoptant une approche qualitative, l' etude a examin e les rapports de r eflexions r edig es par les etudiants a la suite d'un entretien avec un entrepreneur, centr e sur son exp erience de l' echec. A l'aide de ARTICLE HISTORY

CEPAL Review, 2012

Students' performance at the lower secondary level in Uruguay is examined on the basis of the mat... more Students' performance at the lower secondary level in Uruguay is examined on the basis of the mathematics scores compiled by the Programme for International Student Assessment (pisa) for 2003 and 2006. An effort is made to analyse the differences in score distributions, to identify the variables influencing students' performance and to trace the trends over that period and weigh their significance. In order to do so, a production function for educational achievement is defined and a number of different decomposition methodologies are applied. The findings indicate that the small increase in scores between 2003 and 2006 is the net result of differing changes, most of which are primarily the result of an across-the-board increase in the school system's efficiency, especially in the case of public schools. However, this improvement is partially offset by reduced resource endowments and, in particular, unfavourable socioeconomic and cultural conditions in many of the students' households. Most of the changes that are analysed in this study are found to be of a redistributive nature.

International journal of molecular sciences, Jan 8, 2017

Immature, vegetable-like fruits are produced by crops of great economic importance, including cuc... more Immature, vegetable-like fruits are produced by crops of great economic importance, including cucumbers, zucchini, eggplants and bell peppers, among others. Because of their high respiration rates, associated with high rates of dehydration and metabolism, and their susceptibility to chilling injury (CI), vegetable fruits are highly perishable commodities, requiring particular storage conditions to avoid postharvest losses. This review focuses on the oxidative stress that affects the postharvest quality of vegetable fruits under chilling storage. We define the physiological and biochemical factors that are associated with the oxidative stress and the development of CI symptoms in these commodities, and discuss the different physical, chemical and biotechnological approaches that have been proposed to reduce oxidative stress while enhancing the chilling tolerance of vegetable fruits.

International Mathematical Forum, 2007

The extremal number ex(n; MK p) denotes the maximum number of edges of a graph of order n not con... more The extremal number ex(n; MK p) denotes the maximum number of edges of a graph of order n not containing a complete graph K p as a minor. In this paper we find a lower bound for this extremal number in terms of Turán Numbers that improves the only lower bound known up to now and it is best possible for infinitely many values of n and p. This lower bound also allows us to prove that every Turán Graph T r (n) is shown to contain K p as a minor for all n ≥ 2p − 2.

Pensamiento Educativo: Revista de Investigación Educacional Latinoamericana, 2016

Los autores agradecen el financiamiento del Fondo de Investigación y Desarrollo en Educación (FON... more Los autores agradecen el financiamiento del Fondo de Investigación y Desarrollo en Educación (FONIDE) F711296 del Ministerio de Educación de Chile.

Análise dos genes diferencialmente expressos através de microarranjos de DNA (Codelink), durante ... more Análise dos genes diferencialmente expressos através de microarranjos de DNA (Codelink), durante a osteodiferenciação das células C2C12, induzida por rhBMP2 e rhBMP7.

School Effectiveness and School Improvement, 2015

This paper is based on a multiple case study of schools which have been identified as improving t... more This paper is based on a multiple case study of schools which have been identified as improving their performance for about a decade. We proposed different criteria by which to characterize and study these improvement processes and, by applying them to our sample, we elaborated a typology of school improvement trajectories: we identified 4 different trajectories of school improvement. We called the first type restricted improvement because at its center is the management of processes that mainly target academic achievement tests; the second is incipient improvement, which is based on changes that restructure the school processes; the third identified trajectory are cases where school improvement is moving toward institutionalization, while the last are those cases where improvement has been already institutionalized and the schools have achieved high levels of educational effectiveness. We identified challenges that schools face at different stages of school improvement and discussed some related policy issues.

PLOS ONE, 2015

We have studied the effect of individual shrink wrapping (ISW) on the postharvest performance of ... more We have studied the effect of individual shrink wrapping (ISW) on the postharvest performance of refrigerated fruit from two zucchini cultivars that differ in their sensitivity to cold storage: Sinatra (more sensitive) and Natura (more tolerant). The fruit was individually shrink wrapped before storing at 4°C for 0, 7 and 14 days. Quality parameters, ethylene and CO 2 productions, ethylene gene expression, and oxidative stress metabolites were assessed in shrink wrapped and non-wrapped fruit after conditioning the fruit for 6 hours at 20°C. ISW decreased significantly the postharvest deterioration of chilled zucchini in both cultivars. Weight loss was reduced to less than 1%, pitting symptoms were completely absent in ISW fruit at 7 days, and were less than 25% those of control fruits at 14 days of cold storage, and firmness loss was significantly reduced in the cultivar Sinatra. These enhancements in quality of ISW fruit were associated with a significant reduction in coldinduced ethylene production, in the respiration rate, and in the level of oxidative stress metabolites such as hydrogen peroxide and malonyldialdehyde (MDA). A detailed expression analysis of ethylene biosynthesis, perception and signaling genes demonstrated a downregulation of CpACS1 and CpACO1 genes in response to ISW, two genes that are upregulated by cold storage. However, the expression patterns of six other ethylene biosynthesis genes (CpACS2 to CpACS7) and five ethylene signal transduction pathway genes (CpCTR1, CpETR1, CpERS1, CpEIN3.1 and CpEN3.2), suggest that they do not play a major role in response to cold storage and ISW packaging. In conclusion, ISW zucchini packaging resulted in improved tolerance to chilling concomitantly with a reduction in oxidative stress, respiration rate and ethylene production, as well as in the expression of ethylene biosynthesis genes, but not of those involved in ethylene perception and sensitivity.

El estudio analiza el desempeño de la Educación Media en Uruguay utilizando los datos de las prue... more El estudio analiza el desempeño de la Educación Media en Uruguay utilizando los datos de las pruebas PISA Matemática 2003 y 2006. Se buscar investigar la existencia de diferencias en la distribución de puntajes entre ambas pruebas, identificar un conjunto de variables que tienen efecto sobre el desempeño de los alumnos y analizar su evolución e importancia entre ambos años. Para ello se define una función de producción de resultados educativos y se aplican las metodologías de descomposición de diferencias de resultados de Oaxaca-Blinder (1973) y Juhn, Murphy y Pierce (1993), así como la metodología de microsimulaciones siguiendo a Bourguignon, Fournier y Gurgand (1998). La utilización de estas técnicas poco difundidas para el área de la educación resulta un avance metodológico de gran utilidad para entender mejor la evolución de los cambios en los resultados educativos. Las principales conclusiones a las que se arriba se centran en el hecho de que el bajo incremento en el puntaje entre los años 2003 y 2006 esconde movimientos internos que refieren principalmente a una disminución en la dotación de recursos a nivel del estudiante y del centro educativo, y a un aumento generalizado en la eficiencia de los mismos, resultados percibidos especialmente entre los establecimientos públicos. Destaca el hecho de que los cambios se concentran entre las variables a nivel del estudiante, mientras que aquellas a nivel del establecimiento no resultan relevantes para el período. Asimismo, los cambios son en su mayoría redistributivos, reduciendo las brechas entre estudiantes con mejor y peor desempeño educativo a través del tiempo.