El embrollo conceptual alrededor del conocimiento didáctico del contenido

Desde que en 1986 Shulman introdujo el concepto de Conocimiento Didáctico del Contenido, numerosos autores han sugerido modificaciones a las categorías propuestas. El propósito de este trabajo es proporcionar un panorama de cómo ha ido cambiando y desarrollándose la noción del CDC, y de las controversias acerca de la naturaleza y la utilidad del CDC que han ido apareciendo en estos años. Las diferentes visiones que tienen los investigadores acerca del CDC influyen sobre el diseño de sus investigaciones y los métodos utilizados, entonces repensar la conceptualización del CDC nos ayudará a encontrar las líneas de investigación que deberíamos reforzar para poder responder a las preguntas para las cuales aún no se han encontrado respuestas

El embrollo conceptual alrededor del conocimiento didáctico del contenido

Desde que en 1986 Shulman introdujo el concepto de Conocimiento Didáctico del Contenido, numerosos autores han sugerido modificaciones a las categorías propuestas. El propósito de este trabajo es proporcionar un panorama de cómo ha ido cambiando y desarrollándose la noción del CDC, y de las controversias acerca de la naturaleza y la utilidad del CDC que han ido apareciendo en estos años. Las diferentes visiones que tienen los investigadores acerca del CDC influyen sobre el diseño de sus investigaciones y los métodos utilizados, entonces repensar la conceptualización del CDC nos ayudará a encontrar las líneas de investigación que deberíamos reforzar para poder responder a las preguntas para las cuales aún no se han encontrado respuestas

PROPULSION APPARATUS FOR SPACE VEHICLES AND CORRESPONDING METHOD

Propulsion apparatus (10) for space vehicles, comprising a solid state oxygen-rich source layer (11), means (12) for extracting oxygen from said solid state oxygen-rich source layer (11), means (16, 14, 17) for accelerating correspondingly extracted oxygen ions into vacuum. According to the invention, it comprises a stack including said solid state oxygen-rich source layer (11), an active layer (16) being deposited above said solid state oxygen-rich source layer (11), in contact with said solid state oxygen-rich source layer, said active layer (16) being formed with a material different from said solid state oxygen-rich source layer (11), said material being an oxide presenting impedance hysteresis behavior, i.e. a memristor, wherein in a low resistance state oxygen ions (22) are expelled through the active layer (16) and wherein in a high resistance state the active layer (16) ceases expelling oxygen ions (22)

PROPULSION APPARATUS FOR SPACE VEHICLES AND CORRESPONDING METHOD

A propulsion apparatus for space vehicles, includes a solid state oxygen-rich source layer, means for extracting oxygen from said solid state oxygen-rich source layer, means for accelerating correspondingly extracted oxygen ions into vacuum. A stack includes the solid state oxygen-rich source layer, an active layer being deposited above the solid state oxygen-rich source layer, in contact with the solid state oxygen rich source layer, the active layer being formed with a material different from the solid state oxygen-rich source layer, the material being an oxide presenting impedance hysteresis behavior

Campesinato de fronteira, pagamentos e serviços ambientais: análise da expressão diferenciada da lógica de mercado em Anapu, Pará.

Analisando quatro estudos de caso no município de Anapu, no Pará, este artigo contrasta duas abordagens para a provisão de serviços ambientais: através do pagamento em efetivo para conservação, ou pagamento por serviços ambientais (PSA), e do apoio a sistemas sustentáveis agrícolas e florestais. As abordagens são avaliadas à luz da teoria do campesinato de fronteira, destacando-se como conclusão que a abordagem de ?PSA de conservação? não se mostra adequada para replicação nesse contexto, enquanto as demais abordagens são mais adequadas no propósito de aliar conservação ambiental e produção sustentável, desde que o acesso aos recursos financeiros e de capital humano se consolide com perspectivas de longo praz

In vivo cranial bone strain and bite force in the agamid lizard Uromastyx geyri

In vivo bone strain data are the most direct evidence of deformation and strain regimes in the vertebrate cranium during feeding and can provide important insights into skull morphology. Strain data have been collected during feeding across a wide range of mammals; in contrast, in vivo cranial bone strain data have been collected from few sauropsid taxa. Here we present bone strain data recorded from the jugal of the herbivorous agamid lizard Uromastyx geyri along with simultaneously recorded bite force. Principal and shear strain magnitudes in Uromastyx geyri were lower than cranial bone strains recorded in Alligator mississippiensis, but higher than those reported from herbivorous mammals. Our results suggest that variations in principal strain orientations in the facial skeleton are largely due to differences in feeding behavior and bite location, whereas food type has little impact on strain orientations. Furthermore, mean principal strain orientations differ between male and female Uromastyx during feeding, potentially because of sexual dimorphism in skull morphology

Agência e contingência no acesso à terra e reprodução social camponesa no vale do rio Mearim, estado do Maranhão.

Neste artigo, examinamos as trajetórias familiares de três lideranças rurais no vale do Mearim, que ilustram as principais formas de acesso e ocupação da terra protagonizadas pelo campesinato maranhense nos últimos 150 anos. A análise dessas trajetórias tomadas como alegorias permite apresentar as contingências vividas por este campesinato que, a despeito das interações desfavoráveis na estrutura social e sob o aparato legal do Estado brasileiro, agencia sua reprodução social, fundada na permanência na terra. Nos três casos estudados, frente a essas contingências, os processos de ação coletiva e a articulação política protagonizados pelos entrevistados representam descontinuidades entre gerações, com consequências distintas para as respectivas trajetórias familiares. Em apenas um dos casos, são mantidos práticas e discursos que expandiram a base agrária do grupo familiar, em contraste com as aparentes estagnação e contração observadas nos demais casos. A análise aponta a relevância da relação da unidade familiar com o mercado formal de terras, assim como das relações sociopolíticas estabelecidas para além do parentesco, para a definição das possibilidades do campesinato no rural contemporâneo

Design of an Intrinsically Motivating AR Experience for Environmental Awareness

Augmented Reality seems a promising tool to provide engaging and effective educational experiences, thanks to its potentiality in stimulating intrinsic motivation, that could influence the learning process and the attitude of the users towards behaviours. This paper presents the Resized Plastic Augmented Reality learning experience, designed on the basis of Dunleavy's framework to provide a systemic overview of the microplastics issue to allow users to understand its mechanisms, educate them about their role in the system and help them to connect this information to their everyday actions

A BIOGECHEMICAL APPROACH FOR THE ENVIRONMENTAL CHARACTERISATION OF MINE LANDS

Abstract The determination of PTE environmental impacts at mine lands is a complex issues, since it regards different environmental matrix, as earth material (soils and waste-rocks), superficial and underground waters and also living beings. All of these can be investigated by biogeochemical tools, as they are very useful to understand how PTE move from waste-rocks to the surrounding ecosystems and how a careful mine land management can control their impacts. This project was carried out in order to check and develop analytical methodologies for the evaluation of: 1. PTE contamination of earth materials (soil or waste rock), with a special care for arsenic, one of the most dangerous elements for human health; 2. AMD evaluation, by the application of different analytical methodologies (static and kinetic tests); 3. biogeochemical features of wild flora growing on mine sites, in order to collect useful information for mine lands remediation. AMD evaluation was done by the applications of AMIRA procedure (IWRI & EGI, 2002), that allowed to identify the acid production or neutralising potential of earth materials. Moreover, an important tool for geochemical assessment of abandoned mine-waste dumps was applied, as it is a quick, cost-effective and qualitative leach procedure, designed by the Environmental Protection Agency (1994) to evaluate the impact of contaminated earth material on groundwaters. This kinetic test provides an insight into the behaviour of the waste-rocks during the interaction with meteoric water and gives useful indication of the potential chemical composition of the run-off from the weathered surface of mining areas. Moreover, the relationship between earth materials and plants growing on mine areas were investigated and metal tolerance strategies were identify by the calculation of the appropriate biogeochemical parameters as Bioaccumulation Factor and Traslocation Factor. These approaches have been developed on two ancient mine sites, with different geo-environmental setting: Rosia Montana mining area (Romania) and Gromo-Gandellino mining area (Valseriana, Northern Italy). Rosia Montana mining area (Romania) is a hydrothermal gold deposit hosted in andesites and dacites of Neogene age, piercing the pre-volcanic sedimentary basement as breccia pipes, that host polymetallic sulphides and Au-Ag-Te mineralisations. Century of exploitation caused a significant environmental damage and the excavation and exploitation of tunnels and open pits has generated a large amount of waste-rocks dumps, some of them located close to villages. Private company provided remediation plans for the past mining activity and mitigation plans for reopening. Gromo-Gandellino ancient mining area is a Ag \u2013 Fe ore deposit made up mainly by sulphide, sulphosalts and carbonate, intensely exploited in the medieval epoch and abandoned in the early decades of 20th century. The area is not exploited at the present time, but the numerous underground cavities and waste-rock dumps, some of them located very closed to villages, testify the historical activities linked to the exploitation of Fe, Zn, Pb, Ag and Cu mineralisations. At Hop waste-rock dump (Rosia Montana mine site, Romania) the spatial heterogeneity is well represented. Earth material is composed by two different rock types: (1) the so-called WR1 samples, a source of acid drainage ; and (2) the WR2 samples, able to buffer the production of acidic water. On the whole, Hop waste rock dump is however a source of acid drainage, as showed both by static and kinetic tests. These last have confirmed to be an important tools for geochemical assessment of abandoned mine-waste dumps, as they are a quick, cost-effective and qualitative leach procedure to evaluate the impact of contaminated earth material on groundwater and to assess metal mobilisation from waste-rocks. The tree species growing on Hop waste-rock dump, belonging to Salix spp., B. pendula and P. tremula, are able to tolerate limiting conditions (such as acid pH values and mean As content of 80 mg/kg), as known from the literature. They actively accumulate Cu and Zn in their tissues, specially in leaves, although they can not be considered as hyper-accumulators. On the other hand, the same species act as excluders for As, whose concentration in plant tissues are lower than in soils, exceeding however toxic values.\uf020Salix spp. represents the species more able to tolerate different environmental situations and to grow on strong acid substrates, acting as a pioneer species that could be used for revegetation of mine lands and stabilization of dump slopes, even on the area still not vegetated. At Gromo-Gandellino mine site, the occurrence of waste-rock dumps represents an environmental hazard for the area: soil heavy metal concentrations is about one order of magnitude higher than in natural soils, specially at Coren del Cuc\uec site, located in the vicinity of Gromo village. The mining area is colonised by the metal tolerant species C. vulgaris and D. filix-mas. These plants behave as excluders and accumulation occurs only in roots, where internal metal detoxification mechanisms might exist in addition to exclusion strategies. So, they can be used surely as slope dump \u201cstabilizators\u201d and, in particular, C. vulgaris appears interesting for mine land restoration and soil stabilization of Cu, Zn, Pb, Ni, Cd and As. The biogeochemical characterisation of these mine lands gave useful information to support their management, as it provided information for the choice of sites that need priority remediation activities, and identified, within these sites, the areas responsible for contamination. Moreover, the identification of metal tolerance species and their strategies provided useful information for project of rehabilitation, but also highlighted how PTE move through food webs