2,549 research outputs found
Identificación, evaluación y prevención de riesgos en las colecciones de restos momificados: el caso práctico del Museo Reverte Coma
X Congreso Nacional de Paleopatología. Univesidad Autónoma de Madrid, septiembre de 200
La participación del alumnado en el Proyecto Piloto "Agenda 21 Escolar" en Málaga
En la ciudad de Málaga se puso marcha, en otoño del 2013, un proceso participativo donde la comunidad educativa se comprometía a trabajar la sostenibilidad y la calidad ambiental siguiendo la metodología de la Agenda 21 local. Para lograrlo, se creó el Programa Educativo Agenda 21 escolar, cuyos componentes básicos son la participación comunitaria, la gestión sostenible del centro educativo y del municipio y la innovación curricular. Siete centros educativos se adscribieron al programa, eligieron una temática ambiental y la trabajaron durante el curso en cinco fases: organización y planificación, sensibilización y motivación, diagnóstico y reflexión, plan de acción y evaluación. De este modo, cada centro educativo creó su propio proyecto. El proyecto Agenda 21 escolar brinda la oportunidad a toda la comunidad educativa que exista una participación activa en las dinámicas de enseñanza formal y no formal, en el propio centro educativo y en su ámbito local, donde la participación del alumnado es clave para alcanzar su éxito. Por ello, el objetivo de la investigación fue evaluar la participación de una muestra de 84 alumnos/as del tercer curso de Educación Secundaria Obligatoria perteneciente a cinco centros educativos pilotos adscritos al programa. El paradigma de la investigación es empírico-analítico y el diseño descriptivo. El instrumento que se utilizó para medir la participación fue un cuestionario de escala aditiva de Likert formado por veinte ítems. El cuestionario usado fue cerrado y ordinal, de este modo los datos que se obtuvieron se pudieron tratar en hojas de cálculo. En cada centro educativo se averiguó la puntuación total que cada estudiante obtuvo del cuestionario, así como la de los/as coordinadores/as. También se calcularon las medianas y las modas en cada ítem por centro educativo, el porcentaje de las frecuencias de las respuestas del alumnado en cada fase, y el porcentaje final de la participación de la muestra en el proyecto. Se elaboraron tablas y gráficas, facilitando la interpretación de los resultados, y se comprobaron si se alcanzaron los objetivos propuestos en la investigación. Una vez analizados los resultados se concluyó que la participación de la muestra en todas las fases del proyecto no fue verdadera, salvo en la fase del plan de acción donde la participación del alumnado fue informada pero sólo asignada, es decir, en esta fase el alumnado se limitó a realizar las actividades que les propuso el profesorado.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
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Cardiovascular Risk Factors and Dehydroepiandrosterone Sulfate Among Latinos in the Boston Puerto Rican Health Study.
Low blood dehydroepiandrosterone sulfate (DHEAS) levels have strong positive associations with stroke and coronary heart disease. However, it is unclear whether DHEAS is independently associated with cardiovascular risk factors. Therefore, we examined the association between cardiovascular risk factors and DHEAS concentration among a high-risk population of Latinos (Puerto Ricans aged 45 to 75 years at baseline) in a cross-sectional analysis of the Boston Puerto Rican Health Study. Of eligible participants, 72% completed baseline interviews and provided blood samples. Complete data were available for 1355 participants. Associations between cardiovascular risk factors (age, sex, total cholesterol, high-density lipid cholesterol, triglycerides, and glucose) and log-transformed DHEAS (μg/dL) were assessed. In robust multivariable regression analyses, DHEAS was significantly inversely associated with age (β = -12.4; 95% CI: -15.2, -9.7; per 5 years), being female (vs. male) (β = -46; 95% CI: -55.3, -36.6), and plasma triglyceride concentration (β = -0.2; 95% CI: -0.3, -0.1; per 10 mg/dL) and was positively associated with total cholesterol and plasma glucose levels (β = 1.8; 95% CI: 0.6, 3 and β = 0.2; 95% CI: 0.04, 0.3, respectively, per 10 mg/dL) after adjustment for smoking, alcohol, and physical activity and for postmenopausal hormone use in women. Estimates were unchanged after adjustment for measures of chronic disease and inflammation. Women exhibited a stronger age-related decline in DHEAS and a positive association with glucose in contrast to findings among men (P interaction < 0.05). In conclusion, in this large study of Latinos with a heavy cardiovascular risk factor burden, we observed significant associations between cardiovascular disease (CVD) risk factors and DHEAS, with variations by sex. These findings improve our understanding of the role DHEAS may play in CVD etiology
Structural and morphological evolution of powders nanostructured ceramics: transitional aluminas
This work aims with the study of the transformation of boehmite into transitional aluminas. Boehmite was obtained by a sol-gel method from an aluminium hazardous waste. The thermal behaviour of boehmite was followed by thermogravimetry and differential thermal analysis to determine the transformation temperatures. By calcinations of boehmite at temperatures ranging between 250-1000ºC, transitional aluminas (?, ? , ?-Al2O3) were synthesized and characterized by XRD, TEM and FTIR. All the transitional aluminas exhibit nanometric crystallite size, ranging from 2.5-15nm. ?-Al2O3 was obtained as a nanostructured material at 500ºC with a cell parameter a=7.923Å. ?-phase stars to appear at 850ºC with a crystallite size of 6nm and cell parameters a=5.672Å and c=24.600Å. For ?-Al2O3 the cell parameters, in Å, were a=11.817, b=2.912, c=5.621 and ?=103.8º. The progressive conversion of the transitional phase ?-Al2O3 into the stable polymorph ?-alumina, takes place gradually and a four-phases region is achieved at 1000ºC, where coexist with other transitional phase such as ?- and ?-Al2O3
On the Lebesgue measure of Li-Yorke pairs for interval maps
We investigate the prevalence of Li-Yorke pairs for and
multimodal maps with non-flat critical points. We show that every
measurable scrambled set has zero Lebesgue measure and that all strongly
wandering sets have zero Lebesgue measure, as does the set of pairs of
asymptotic (but not asymptotically periodic) points.
If is topologically mixing and has no Cantor attractor, then typical
(w.r.t. two-dimensional Lebesgue measure) pairs are Li-Yorke; if additionally
admits an absolutely continuous invariant probability measure (acip), then
typical pairs have a dense orbit for . These results make use of
so-called nice neighborhoods of the critical set of general multimodal maps,
and hence uniformly expanding Markov induced maps, the existence of either is
proved in this paper as well.
For the setting where has a Cantor attractor, we present a trichotomy
explaining when the set of Li-Yorke pairs and distal pairs have positive
two-dimensional Lebesgue measure.Comment: 41 pages, 3 figure
Magnetite mineralization inside cross-linked protein crystals
Crystallization in confined spaces is a widespread process in nature that also has important implications for the stability and durability of many man-made materials. It has been reported that confinement can alter essential crystallization events, such as nucleation and growth and, thus, have an impact on crystal size, polymorphism, morphology, and stability. Therefore, the study of nucleation in confined spaces can help us understand similar events that occur in nature, such as biomineralization, design new methods to control crystallization, and expand our knowledge in the field of crystallography. Although the fundamental interest is clear, basic models at the laboratory scale are scarce mainly due to the difficulty in obtaining well-defined confined spaces allowing a simultaneous study of the mineralization process outside and inside the cavities. Herein, we have studied magnetite precipitation in the channels of cross-linked protein crystals (CLPCs) with different channel pore sizes, as a model of crystallization in confined spaces. Our results show that nucleation of an Fe-rich phase occurs inside the protein channels in all cases, but, by a combination of chemical and physical effects, the channel diameter of CLPCs exerted a precise control on the size and stability of those Fe-rich nanoparticles. The small diameters of protein channels restrain the growth of metastable intermediates to around 2 nm and stabilize them over time. At larger pore diameters, recrystallization of the Fe-rich precursors into more stable phases was observed. This study highlights the impact that crystallization in confined spaces can have on the physicochemical properties of the resulting crystals and shows that CLPCs can be interesting substrates to study this process
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