Aprendizaje elemental a pesar de entrenamiento configuracional en una tarea de navegación

Se entrenó a unas ratas a encontrar una plataforma invisible definida por una configuración de dos objetos en la mitad de los ensayos y por una segunda configuración de dos objetos en la otra mitad. Los objetos estaban espaciados alrededor del borde de la piscina. Las dos configuraciones se presentaron con la misma frecuencia cada día, entremezcladas semi-al azar. En el Experimento 1, las configuraciones de las ratas fueron A y B (configuración 1), y B y C (configuración 2). B era un objeto común a ambas configuraciones. Al final de esta fase los animales recibieron ensayos de prueba en los que se colocaba a una rata en la piscina sin la plataforma y se registraba el tiempo que pasaba en el cuadrante de la plataforma. Los animales tuvieron ensayos de prueba con las configuraciones del entrenamiento, con los objetos por separado, y con una nueva configuración, A y C (una prueba de integración). Tanto ante las configuraciones del entrenamiento como en presencia de B, las ratas pasaron una cantidad de tiempo sustancial buscando la plataforma en el cuadrante de la plataforma; no se obtuvo ningún otro efecto en las otras pruebas. En el Experimento 2 se introdujeron varios cambios metodológicos y se replicaron los principales resultados del Experimento 1. Concluimos que tras un entrenamiento configuracional como el empleado, la navegación de las ratas hacia una plataforma invisible estuvo controlada por un aprendizaje elemental, por B.

Elemental analysis of wood materials by external millibeam thick target PIXE

PIXE (Particle Induce X-ray Emission spectrometry) was used for analysing stem bark and stem wood of Scots pine, Norway spruce and Silver birch. Thick samples were irradiated, in laboratory atmosphere, with 3 MeV protons and the beam current was measured indirectly using a photo multiplicator (PM) tube. Both point scans and bulk analyses were performed with the 1 mm diameter proton beam. In bulk analyses, whole bark and sectors of discs of the stem wood were dry ashed at 550 ˚C. The ashes were homogenised by shaking and prepared to target pellets for PIXE analyses. This procedure generated representative samples to be analysed, but the enrichment also enabled quantification of some additional trace elements. The ash contents obtained as a product of the sample preparation procedure also showed to be of great importance in the evaluation of results in environmental studies. Spot scans from the pith of pine wood outwards, showed clearly highest concentrations of manganese, calcium and zinc in the first spot irradiated, or 2-3 times higher than in the surrounding wood. For stem wood from the crown part of a pine this higher concentration level was found in the first four spots/mms, including the pith and the two following growth rings. Zinc showed increasing concentrations outwards in sapwood of the pine stem, with the over-all lowest concentrations in the inner half of the sapwood. This could indicate emigration of this element from sapwood being under transformation to heartwood. Point scans across sapwood of pine and spruce showed more distinct variations in concentrations relative to hearth wood. Higher concentrations of e.g. zinc, calcium and manganese were found in earlywood than in denser latewood. Very high concentrations of iron and copper were also seen for some earlywood increments. The ash content of stem bark is up to and order higher than for the stem wood. However, when the elemental concentration in ashes of bark and wood of the same disc were compared, these are very similar – this when trees are growing at spots with no anthropogenic contamination from the atmosphere. The largest difference was obtained for calcium which appeared at two times high concentrations in ashes of bark than in ashes of the wood (ratio of 2). Pine bark is often used in monitoring of atmospheric pollution, where concentrations in bark samples are compared. Here an alternative approach is suggested: Bark and the underlying stem wood of a pine trees are dry ashed and analysed. The elemental concentration in the bark ash is then compared to the concentration of the same element in the wood ash. Comparing bark to wood includes a normalisation for the varying availability of an element from the soil at different sites. When this comparison is done for the ashes of the materials, a normalisation is also obtained for the general and locally different enrichment of inorganic elements from wood to bark. Already a ratio >2 between the concentration in the bark ash and the concentration in the wood ash could indicate atmospheric pollution. For monitoring where bark is used, this way of “inwards” comparison is suggested - instead of comparing to results from analyses of bark from other trees (read reference areas), growing at sites with different soil and, locally, different climate conditions. This approach also enables evaluation of atmospheric pollution from sampling of only relative few individual trees –preferable during forest felling.

Disturbance and ecosystem functioning : the role of changes in benthic biological traits

Rapid changes in biodiversity are occurring globally, as a consequence of anthropogenic disturbance. This has raised concerns, since biodiversity is known to significantly contribute to ecosystem functions and services. Marine benthic communities participate in numerous functions provided by soft-sedimentary ecosystems. Eutrophication-induced oxygen deficiency is a growing threat against infaunal communities, both in open sea areas and in coastal zones. There is thus a need to understand how such disturbance affects benthic communities, and what is lost in terms of ecosystem functioning if benthic communities are harmed. In this thesis, the status of benthic biodiversity was assessed for the open Baltic Sea, a system severely affected by broad-scale hypoxia. Long-term monitoring data made it possible to establish quantitative biodiversity baselines against which change could be compared. The findings show that benthic biodiversity is currently severely impaired in large areas of the open Baltic Sea, from the Bornholm Basin to the Gulf of Finland. The observed reduction in biodiversity indicates that benthic communities are structurally and functionally impoverished in several of the sub-basins due to the hypoxic stress. A more detailed examination of disturbance impacts (through field studies and -experiments) on benthic communities in coastal areas showed that changes in benthic community structure and function took place well before species were lost from the system. The degradation of benthic community structure and function was directed by the type of disturbance, and its specific temporal and spatial characteristics. The observed shifts in benthic trait composition were primarily the result of reductions in species’ abundances, or of changes in demographic characteristics, such as the loss of large, adult bivalves. Reduction in community functions was expressed as declines in the benthic bioturbation potential and in secondary biomass production. The benthic communities and their degradation accounted for a substantial proportion of the changes observed in ecosystem multifunctionality. Individual ecosystem functions (i.e. measures of sediment ecosystem metabolism, elemental cycling, biomass production, organic matter transformation and physical structuring) were observed to differ in their response to increasing hypoxic disturbance. Interestingly, the results suggested that an impairment of ecosystem functioning could be detected at an earlier stage if multiple functions were considered. Importantly, the findings indicate that even small-scale hypoxic disturbance can reduce the buffering capacity of sedimentary ecosystem, and increase the susceptibility of the system towards further stress. Although the results of the individual papers are context-dependent, their combined outcome implies that healthy benthic communities are important for sustaining overall ecosystem functioning as well as ecosystem resilience in the Baltic Sea.

Perennial negotiations/elemental encounters autoethnographic perspectives on approaching food sovereignty

This thesis uses a multifaceted process to engage with the topic of food sovereignty in California. It employs diverse methods, including critical and creative prose, photography, autoethnographic mixed media, storytelling and poetry. I am particularly concerned with the " " challenges of approaching food sovereignty, a radical praxis that combines subsistence practices with anti-capitalist resistance, while in my own "skin," which is thoroughly embedded in white, urban, middle classed culture and in corltextualizing ecological relationshipslkinships via cultural, historical and economic trajectories. The project utilizes a processual methodlology drawing substantially from the work of Brian Massumi to explore these issues through four creative narrative pieces which coalesce around the elemental metaphors of air, fire, water and earth. Following Deleuze and Guatarri's concept ofrhizomatic plateaus, the thesis narratives are comprised of many non-hierarchical layers and can be read from many angles. Each is offered "in process" rather than as a finished piece, thus practically validating the concept of the ongoing work of research and suggesting the equally omnipresent possibility of change and mutation in the formation relationally based knowledges. Cultivating ecological ethic and healing on multisensory levels, as well as commitment to emergent and re-productivist worldviews are goals of this project's research.

Análisis de factores aplicado a datos de composición elemental de materia particulada suspendida en la zona noroeste de la ciudad de Monterrey por Juana María Montoya Zamora

Tesis (Maestría en Ciencias con Especialidad en Ingeniería Cerámica) U.A.N.L.

Manual elemental del derecho de la guerra ; traducción de la parte que con relación a esta materia contiene El manual elemental de derecho internacional público

UANL

Tratado elemental de la destreza del sable

UANL

Curso de filosofía elemental

UANL

Curso elemental teórico-práctico del teneduria de libros por partida doble

UANL

La enseñanza elemental (sus principios y su práctica)

UANL

Nueva aritmética elemental

UANL

Geometría elemental

UANL

Tratado de geometría elemental : adoptado como texto en la Escuela Nacional Preparatoria

UANL

La enseñanza elemental : guía teórica práctica para la instrucción primaria en la ...

UANL

Moral práctica en el primer año elemental.

UANL