Arthur Douglas : missionary on Lake Nyasa, the story of his life

http://www.archive.org/details/arthurdouglasmi00douguoft

Analysis of institutional arrangements and common pool resources governance: the case of Lake Tana sub-basin, Ethiopia

Although Common Pool Resources (CPRs) make up a significant share of total income for rural households in Ethiopia and elsewhere in developing world, limited access to these resources and environmental degradation threaten local livelihoods. As a result, the issues of management, governance of CPRs and how to prevent their over-exploitation are of great importance for development policy. This study examines the current state and dynamics of CPRs and overall resource governance system of the Lake Tana sub-basin. This research employed the modified form of Institutional Analysis and Development (IAD) framework. The framework integrates the concept of Socio-Ecological Systems (SES) and Interactive Governance (IG) perspectives where social actors, institutions, the politico-economic context, discourses and ecological features across governance and government levels were considered. It has been observed that overexploitation, degradation and encroachment of CPRs have increased dramatically and this threatens the sustainability of Lake Tana ecosystem. The stakeholder analysis result reveals that there are multiple stakeholders with diverse interest in and power over CPRs. The analysis of institutional arrangements reveals that the existing formal rules and regulations governing access to and control over CPRs could not be implemented and were not effective to legally bind and govern CPR user’s behavior at the operational level. The study also shows that a top-down and non-participatory policy formulation, law and decision making process overlooks the local contexts (local knowledge and informal institutions). The outcomes of examining the participation of local resource users, as an alternative to a centralized, command-and-control, and hierarchical approach to resource management and governance, have called for a fundamental shift in CPR use, management and governance to facilitate the participation of stakeholders in decision making. Therefore, establishing a multi-level stakeholder governance system as an institutional structure and process is necessary to sustain stakeholder participation in decision-making regarding CPR use, management and governance.

Geochemistry, mineralogy, and chemical modeling of the acid crater lake of Kawah Ijen volcano, Indonesia

The Kawah Ijen volcano-with a record of phreatic eruptions-has its 1000 m wide crater filled with a lake that has existed for at least one century. At present, the lake waters are hot (T ≈ 37°C), strongly mineralized (TDS = 105 g/L) and extremely acidic (pH ≈ 0.4). By its volume, the Javanese lake is probably the largest accumulation in the world of such acidic waters. Mineralogy of the suspended solids within the lake waters suggests that concentrations of Si, Ca, Ti, and Ba are controlled by precipitation of silica, gypsum, anatase, and barite. Lake sediment is composed of chemical precipitates with composition similar to the suspended solids. Thermodynamic calculations predict that the lake waters have reached equilibrium with respect to α-cristobalite, barite, gypsum, anglesite, celestite, and amorphous silica, in agreement with the analytical observations. Significant concentrations of ferric iron suggest that the current lake waters are fairly oxidized. Sulfides are absent in the water column but are always present in the native S spherules that form porous aggregates which float on the lake. The presence of native S provides direct evidence of more reduced conditions at the lake floor where H2S is probably being injected into the lake. With progressive addition of H2S to the acid waters, native S, pyrite, and enargite are theoretically predicted to be saturated. Reactions between upward streaming H2S-bearing gases discharged by subaqueous fumaroles, and metals dissolved in the acidic waters could initiate precipitation of these sulfides. A model of direct absorption of hot magmatic gases into cool water accounts for the extreme acidity of the crater lake. Results show that strongly acidic, sulfate-rich solutions are formed under oxidizing conditions at high gas/water ratios. Reactions between the acidic fluids and the Ijen andesite were modeled to account for elevated cation concentrations in lake water. Current concentrations of conservative rockforming elements are produced by dissolution of approximately 60 g of andesite per kg of acid solution. Complete neutralization of the acid lake waters by reaction with the wallrock produces a theoretical alteration assemblage equivalent to that observed in volcano-hosted, acid-sulfate epithermal ore deposits. © 1994.

High-field FMRI reveals brain activation patterns underlying saccade execution in the human superior colliculus.

BACKGROUND: The superior colliculus (SC) has been shown to play a crucial role in the initiation and coordination of eye- and head-movements. The knowledge about the function of this structure is mainly based on single-unit recordings in animals with relatively few neuroimaging studies investigating eye-movement related brain activity in humans. METHODOLOGY/PRINCIPAL FINDINGS: The present study employed high-field (7 Tesla) functional magnetic resonance imaging (fMRI) to investigate SC responses during endogenously cued saccades in humans. In response to centrally presented instructional cues, subjects either performed saccades away from (centrifugal) or towards (centripetal) the center of straight gaze or maintained fixation at the center position. Compared to central fixation, the execution of saccades elicited hemodynamic activity within a network of cortical and subcortical areas that included the SC, lateral geniculate nucleus (LGN), occipital cortex, striatum, and the pulvinar. CONCLUSIONS/SIGNIFICANCE: Activity in the SC was enhanced contralateral to the direction of the saccade (i.e., greater activity in the right as compared to left SC during leftward saccades and vice versa) during both centrifugal and centripetal saccades, thereby demonstrating that the contralateral predominance for saccade execution that has been shown to exist in animals is also present in the human SC. In addition, centrifugal saccades elicited greater activity in the SC than did centripetal saccades, while also being accompanied by an enhanced deactivation within the prefrontal default-mode network. This pattern of brain activity might reflect the reduced processing effort required to move the eyes toward as compared to away from the center of straight gaze, a position that might serve as a spatial baseline in which the retinotopic and craniotopic reference frames are aligned.

When strangers pass: processing of mutual and averted social gaze in the superior temporal sulcus.

Using functional magnetic resonance imaging (fMRI), we investigated brain activity evoked by mutual and averted gaze in a compelling and commonly experienced social encounter. Through virtual-reality goggles, subjects viewed a man who walked toward them and shifted his neutral gaze either toward (mutual gaze) or away (averted gaze) from them. Robust activity was evoked in the superior temporal sulcus (STS) and fusiform gyrus (FFG). For both conditions, STS activity was strongly right lateralized. Mutual gaze evoked greater activity in the STS than did averted gaze, whereas the FFG responded equivalently to mutual and averted gaze. Thus, we show that the STS is involved in processing social information conveyed by shifts in gaze within an overtly social context. This study extends understanding of the role of the STS in social cognition and social perception by demonstrating that it is highly sensitive to the context in which a human action occurs.

Different stimuli, different spatial codes: a visual map and an auditory rate code for oculomotor space in the primate superior colliculus.

Maps are a mainstay of visual, somatosensory, and motor coding in many species. However, auditory maps of space have not been reported in the primate brain. Instead, recent studies have suggested that sound location may be encoded via broadly responsive neurons whose firing rates vary roughly proportionately with sound azimuth. Within frontal space, maps and such rate codes involve different response patterns at the level of individual neurons. Maps consist of neurons exhibiting circumscribed receptive fields, whereas rate codes involve open-ended response patterns that peak in the periphery. This coding format discrepancy therefore poses a potential problem for brain regions responsible for representing both visual and auditory information. Here, we investigated the coding of auditory space in the primate superior colliculus(SC), a structure known to contain visual and oculomotor maps for guiding saccades. We report that, for visual stimuli, neurons showed circumscribed receptive fields consistent with a map, but for auditory stimuli, they had open-ended response patterns consistent with a rate or level-of-activity code for location. The discrepant response patterns were not segregated into different neural populations but occurred in the same neurons. We show that a read-out algorithm in which the site and level of SC activity both contribute to the computation of stimulus location is successful at evaluating the discrepant visual and auditory codes, and can account for subtle but systematic differences in the accuracy of auditory compared to visual saccades. This suggests that a given population of neurons can use different codes to support appropriate multimodal behavior.

The frontal eye field sends predictively remapped visual signals to the superior colliculus

We perceive a stable visual world even though saccades often move our retinas. One way the brain may achieve a stable visual percept is through predictive remapping of visual receptive fields: just before a saccade, the receptive field of many neurons moves from its current location ("current receptive field") to the location it is expected to occupy after the saccade ("future receptive field"). Goldberg and colleagues found such remapping in cortical areas, e.g. in the frontal eye field (FEF), as well as in the intermediate layers of the superior colliculus (SC). In the present study we investigated the source of the SC's remapped visual signals. Do some of them come from the FEF? We identified FEF neurons that project to the SC using antidromic stimulation. For neurons with a visual response, we tested whether the receptive field shifted just prior to making a saccade. Saccadic amplitudes were chosen to be as small as possible while clearly separating the current and future receptive fields; they ranged from 5-30 deg. in amplitude and were directed contraversively. The saccadic target was a small red spot. We probed visual responsiveness at the current and future receptive field locations using a white spot flashed at various times before or after the saccade. Predictive remapping was indicated by a visual response to a probe flashed in the future receptive field just before the saccade began. We found that many FEF neurons projecting to the SC exhibited predictive remapping. Moreover, the remapping was as fast and strong as any previously reported for FEF or SC. It is clear, therefore, that remapped visual signals are sent from FEF to SC, providing direct evidence that the FEF is one source of the SC's remapped visual signals. Because remapping requires information about an imminent saccade, we hypothesize that remapping in FEF depends on corollary discharge signals such as those ascending from the SC through MD thalamus (Sommer and Wurtz 2002).

Analytical laboratory comparison of major and minor constituents in an active crater lake

info:eu-repo/semantics/published

La inserción laboral de las técnicas forestales de nivel superior egresadas del Instituto Agrotécnico Víctor Navajas Centeno (IAVNC)

La educación superior asume el desafío de promover igualdad de oportunidades en la formación académica. Pero, la igualdad de acceso o el éxito en la trayectoria educativa no implican necesariamente igualdad de oportunidades en la inserción ni en la trayectoria en el mercado laboral. Si bien la educación superior favorece la situación de emplabilidad, se reconoce que la cuestión género atraviesa el mercado de trabajo, en tanto institución socialmente construída. Esta investigación toma esta problemática para una formación específica : Técnicas Forestales de Nivel Superior egresadas del Instituto Agrotécnico Víctor Navajas Centeno. Su inserción profesional constituye una preocupación para el sistema formador a partir de indicios que dan cuenta del descenso de la matrícula femenina; la puesta en discusión sobre supuestos sesgos de esta carrera según diferencias de género; la no explicitación, en los acuerdos previos entre el instituto y las empresas forestales sobre criterios de selección y posible segmentación. La hipótesis de trabajo de estea investigación da cuenta de tensiones entre representaciones de equidad y mecanismos de segregación de género en esta particular articulación entre el mundo de la educación y el mundo del trabajo. Siendo el objetivo general el conocer la vinculación formación - inserción laboral de las técnicas egresadas en el período 1998 - 2007, se privilegió una estrategia metodológica de tipo cualitativo y la entrevista como técnica que permite una mayor profundidad en la construcción de los datos. Fueron entrevistados todos los actores involucrados : graduadas, empleadores y profesores del Instituto. Los resultados obtenidos permiten afirmar el rol de la institución educativa en la obtención del empleo, las ambivalenciasa en el discurso empresarial y la construcción de un campo profesional que segrega ocupaciones según género, la existencia de estrategias de autoempleo y multiocupación que despliegan las graduadas para poner en juego su formación así como el reconocimiento de las heterogeneidades intragénero.

La inserción laboral de las técnicas forestales de nivel superior egresadas del Instituto Agrotécnico Víctor Navajas Centeno (IAVNC)

La educación superior asume el desafío de promover igualdad de oportunidades en la formación académica. Pero, la igualdad de acceso o el éxito en la trayectoria educativa no implican necesariamente igualdad de oportunidades en la inserción ni en la trayectoria en el mercado laboral. Si bien la educación superior favorece la situación de emplabilidad, se reconoce que la cuestión género atraviesa el mercado de trabajo, en tanto institución socialmente construída. Esta investigación toma esta problemática para una formación específica : Técnicas Forestales de Nivel Superior egresadas del Instituto Agrotécnico Víctor Navajas Centeno. Su inserción profesional constituye una preocupación para el sistema formador a partir de indicios que dan cuenta del descenso de la matrícula femenina; la puesta en discusión sobre supuestos sesgos de esta carrera según diferencias de género; la no explicitación, en los acuerdos previos entre el instituto y las empresas forestales sobre criterios de selección y posible segmentación. La hipótesis de trabajo de estea investigación da cuenta de tensiones entre representaciones de equidad y mecanismos de segregación de género en esta particular articulación entre el mundo de la educación y el mundo del trabajo. Siendo el objetivo general el conocer la vinculación formación - inserción laboral de las técnicas egresadas en el período 1998 - 2007, se privilegió una estrategia metodológica de tipo cualitativo y la entrevista como técnica que permite una mayor profundidad en la construcción de los datos. Fueron entrevistados todos los actores involucrados : graduadas, empleadores y profesores del Instituto. Los resultados obtenidos permiten afirmar el rol de la institución educativa en la obtención del empleo, las ambivalenciasa en el discurso empresarial y la construcción de un campo profesional que segrega ocupaciones según género, la existencia de estrategias de autoempleo y multiocupación que despliegan las graduadas para poner en juego su formación así como el reconocimiento de las heterogeneidades intragénero.

Una caracterización del tratamiento y asimilación de contenidos en los cursos de álgebra superior

Las Instituciones de Educación Superior,en México, reportan bajos índices de Eficiencia Terminal, hecho relacionado con la reprobación, como es el caso de la Facultad de Matemáticas de la Universidad Autónoma de Yucatán, donde se presentan altos porcentajes de reprobación en la asignatura de Álgebra. Desarrollamos un estudio cualitativo empleando la etnografía, para caracterizar el tratamiento de los contenidos, otorgado por el profesor, y el nivel de asimilación de estos, por parte de los estudiantes. Identificamos las principales representaciones semióticas empleadas por el profesor, donde concluimos que el tratamiento otorgado a los contenidos es preferentemente algebraico y conjuntista. Además, la práctica de evaluación limita a los estudiantes a reproducir los conceptos enseñados.

O ensino de estatística via projetos: motivaçâo de acesso ao ensino superior de alunos do 3º ano do ensino médio de escolas estaduais em uberaba

A atividade que descrevemos teve como objetivo possibilitar aos alunos e professores supervisores bolsistas do Programa de Bolsas de Iniciação à Docência - PIBID do curso de Matemática da Universidade Federal do Triângulo Mineiro em Uberaba, Minas Gerais, a prática da estatística através de atividades de ensino utilizando projetos. Assim, através da aplicação de um questionário a 198 alunos do 3º ano do Ensino Médio de duas escolas estaduais pretendeu-se compreender os problemas que afetam a escolha profissional e a motivação ou não em continuar os estudos. Os resultados indicaram que a maioria dos alunos pretende dar continuidade aos estudos e o que dificultaria esse processo seria: condições financeiras e disponibilidade de tempo. Evidenciamos que as atividades de organização de pesquisa de campo, coleta, tabulação de dados, interpretação e análise dos dados despertou o espírito investigativo nos alunos.

Explotando los conocimientos geométricos de los alumnos de enseñanza media superior

La enseñanza de la Geometría es una ramificación de las Matemáticas que tiene una importancia fundamental en el razonamiento de los chicos y chicas de cualquiera nivel de la Educación Básica. El presente artículo tiene como objetivo presentar los resultados obtenidos de la evaluación diagnostica de Geometría Euclidiana Plana en los alumnos de Enseñanza Medio Superior. La metodología utilizada ha sido la Cuantitativa con Estudio Descriptivo. La muestra ha sido compuesta de 534 alumnos de cuatro escuelas particulares de Enseñanza Mediana de Belém – Pará – Brasil. Ha sido aplicado un cuestionario con cinco cuestiones básicas de Geometría. Los resultados muestran que los discentes están llegando en la enseñanza medio superior con poco o casi ningún conocimiento de Geometría.