'Neurons in Action' in Action - Educational settings for simulations and tutorials using NEURON

Neurons in Action (NIA1, 2000; NIA1.5, 2004; NIA2, 2007), a set of tutorials and linked simulations, is designed to acquaint students with neuronal physiology through interactive, virtual laboratory experiments. Here we explore the uses of NIA in lecture, both interactive and didactic, as well as in the undergraduate laboratory, in the graduate seminar course, and as an examination tool through homework and problem set assignments. NIA, made with the simulator NEURON (http://www.neuron.yale.edu/neuron/), displays voltages, currents, and conductances in a membrane patch or signals moving within the dendrites, soma and/or axon of a neuron. Customized simulations start with the plain lipid bilayer and progress through equilibrium potentials; currents through single Na and K channels; Na and Ca action potentials; voltage clamp of a patch or a whole neuron; voltage spread and propagation in axons, motoneurons and nerve terminals; synaptic excitation and inhibition; and advanced topics such as channel kinetics and coincidence detection. The user asks and answers "what if" questions by specifying neuronal parameters, ion concentrations, and temperature, and the experimental results are then plotted as conductances, currents, and voltage changes. Such exercises provide immediate confirmation or refutation of the student's ideas to guide their learning. The tutorials are hyperlinked to explanatory information and to original research papers. Although the NIA tutorials were designed as a sequence to empower a student with a working knowledge of fundamental neuronal principles, we find that faculty are using the individual tutorials in a variety of educational situations, some of which are described here. Here we offer ideas to colleagues using interactive software, whether NIA or another tool, for educating students of differing backgrounds in the subject of neurophysiology.

An in-situ surface electrochemistry approach toward whole-cell studies: Charge transfer between Geobacter sulfurreducens and electrified metal/electrolyte interfaces through linker molecules

Electrochemical reactivity and structure properties of electrogenic bacteria, Geobacter sulfurreducens (Gs) were studied to explore the heterogeneous electron transfer at the bacteria/electrode interface using electrochemical and in-situ spectroscopic techniques. The redox behavior of Gs adsorbed on a gold electrode, which is modified with a ω-functionalized self-assembled monolayer (SAM) of alkanethiols, depends strongly on the terminal group. The latter interacts directly with outermost cytochromes embedded into the outer membrane of the Gs cells. The redox potential of bacterial cells bound electrostatically to a carboxyl-terminated SAM is close to that observed for bacteria attached to a bare gold electrode, revealing a high electronic coupling at the cell/SAM interface. The redox potentials of bacterial cells adsorbed on amino- and pyridyl-terminated SAMs are significantly different suggesting that the outermost cytochromes changes their conformation upon adsorption on these SAMs. No redox activity of Gs was found with CH3-, N(CH3)3+- and OH-terminated SAMs. Complementary in-situ spectroscopic studies on bacteria/SAMs/Au electrode assemblies were carried out to monitor structure changes of the bacterial cells upon polarization. Spectro-electrochemical techniques revealed the electrochemical turnover of the oxidized and reduced states of outer membrane cytochromes (OMCs) in Gs, providing evidence that the OMCs are responsible for the direct electron transfer to metal electrodes, such as gold or silver, during the electricity production. Furthermore, we observed spectroscopic signatures of the native structure of the OMCs and no conformational change during the oxidation/reduction process of the microorganisms. These findings indicate that the carboxyl-anchoring group provides biocompatible conditions for the outermost cytochromes of the Gs, which facilitate the heterogeneous electron transfer at the microorganism/electrode interface.

Next-generation tissue microarray (ngTMA) increases the quality of biomarker studies: an example using CD3, CD8, and CD45RO in the tumor microenvironment of six different solid tumor types

Background Tissue microarray (TMA) technology revolutionized the investigation of potential biomarkers from paraffin-embedded tissues. However, conventional TMA construction is laborious, time-consuming and imprecise. Next-generation tissue microarrays (ngTMA) combine histological expertise with digital pathology and automated tissue microarraying. The aim of this study was to test the feasibility of ngTMA for the investigation of biomarkers within the tumor microenvironment (tumor center and invasion front) of six tumor types, using CD3, CD8 and CD45RO as an example. Methods Ten cases each of malignant melanoma, lung, breast, gastric, prostate and colorectal cancers were reviewed. The most representative H&E slide was scanned and uploaded onto a digital slide management platform. Slides were viewed and seven TMA annotations of 1 mm in diameter were placed directly onto the digital slide. Different colors were used to identify the exact regions in normal tissue (n = 1), tumor center (n = 2), tumor front (n = 2), and tumor microenvironment at invasion front (n = 2) for subsequent punching. Donor blocks were loaded into an automated tissue microarrayer. Images of the donor block were superimposed with annotated digital slides. Exact annotated regions were punched out of each donor block and transferred into a TMA block. 420 tissue cores created two ngTMA blocks. H&E staining and immunohistochemistry for CD3, CD8 and CD45RO were performed. Results All 60 slides were scanned automatically (total time < 10 hours), uploaded and viewed. Annotation time was 1 hour. The 60 donor blocks were loaded into the tissue microarrayer, simultaneously. Alignment of donor block images and digital slides was possible in less than 2 minutes/case. Automated punching of tissue cores and transfer took 12 seconds/core. Total ngTMA construction time was 1.4 hours. Stains for H&E and CD3, CD8 and CD45RO highlighted the precision with which ngTMA could capture regions of tumor-stroma interaction of each cancer and the T-lymphocytic immune reaction within the tumor microenvironment. Conclusion Based on a manual selection criteria, ngTMA is able to precisely capture histological zones or cell types of interest in a precise and accurate way, aiding the pathological study of the tumor microenvironment. This approach would be advantageous for visualizing proteins, DNA, mRNA and microRNAs in specific cell types using in situ hybridization techniques.

Thermal and Barometric Constraints on the Intrusive and Unroofing History of the Black Mountains: Implications for Timing, Initial Dip, and Kinematics of Detachment Faulting in the Death-Valley Region, California

Unroofing of the Black Mountains, Death Valley, California, has resulted in the exposure of 1.7 Ga crystalline basement, late Precambrian amphibolite facies metasedimentary rocks, and a Tertiary magmatic complex. The Ar-40/Ar-39 cooling ages, obtained from samples collected across the entire length of the range (>55 km), combined with geobarometric results from synextensional intrusions, provide time-depth constraints on the Miocene intrusive history and extensional unroofing of the Black Mountains. Data from the southeastern Black Mountains and adjacent Greenwater Range suggest unroofing from shallow depths between 9 and 10 Ma. To the northwest in the crystalline core of the range, biotite plateau ages from approximately 13 to 6.8 Ma from rocks making up the Death Valley turtlebacks indicate a midcrustal residence (with temperatures >300-degrees-C) prior to extensional unroofing. Biotite Ar-40/Ar-39 ages from both Precambrian basement and Tertiary plutons reveal a diachronous cooling pattern of decreasing ages toward the northwest, subparallel to the regional extension direction. Diachronous cooling was accompanied by dike intrusion which also decreases in age toward the northwest. The cooling age pattern and geobarometric constraints in crystalline rocks of the Black Mountains suggest denudation of 10-15 km along a northwest directed detachment system, consistent with regional reconstructions of Tertiary extension and with unroofing of a northwest deepening crustal section. Mica cooling ages that deviate from the northwest younging trend are consistent with northwestward transport of rocks initially at shallower crustal levels onto deeper levels along splays of the detachment. The well-known Amargosa chaos and perhaps the Badwater turtleback are examples of this "splaying" process. Considering the current distance of the structurally deepest samples away from moderately to steeply east tilted Tertiary strata in the southeastern Black Mountains, these data indicate an average initial dip of the detachment system of the order of 20-degrees, similar to that determined for detachment faults in west central Arizona and southeastern California. Beginning with an initially listric geometry, a pattern of footwall unroofing accompanied by dike intrusion progress northwestward. This pattern may be explained by a model where migration of footwall flexures occur below a scoop-shaped banging wall block. One consequence of this model is that gently dipping ductile fabrics developed in the middle crust steepen in the upper crust during unloading. This process resolves the low initial dips obtained here with mapping which suggests transport of the upper plate on moderately to steeply dipping surfaces in the middle and upper crust.

L' education et l'instruction des enfants chez les anciens Juifs d'après la Bible et le Talmud

par Joseph Simon

STUDIES ON THE PATTERNS OF NUCLEOTIDE AND AMINO ACID SUBSTITUTION (ELECTROPHORESIS, MUTATION RATE, SELECTION, BASE, COMPOSITION)

Theoretical and empirical studies were conducted on the pattern of nucleotide and amino acid substitution in evolution, taking into account the effects of mutation at the nucleotide level and purifying selection at the amino acid level. A theoretical model for predicting the evolutionary change in electrophoretic mobility of a protein was also developed by using information on the pattern of amino acid substitution. The specific problems studied and the main results obtained are as follows: (1) Estimation of the pattern of nucleotide substitution in DNA nuclear genomes. The pattern of point mutations and nucleotide substitutions among the four different nucleotides are inferred from the evolutionary changes of pseudogenes and functional genes, respectively. Both patterns are non-random, the rate of change varying considerably with nucleotide pair, and that in both cases transitions occur somewhat more frequently than transversions. In protein evolution, substitution occurs more often between amino acids with similar physico-chemical properties than between dissimilar amino acids. (2) Estimation of the pattern of nucleotide substitution in RNA genomes. The majority of mutations in retroviruses accumulate at the reverse transcription stage. Selection at the amino acid level is very weak, and almost non-existent between synonymous codons. The pattern of mutation is very different from that in DNA genomes. Nevertheless, the pattern of purifying selection at the amino acid level is similar to that in DNA genomes, although selection intensity is much weaker. (3) Evaluation of the determinants of molecular evolutionary rates in protein-coding genes. Based on rates of nucleotide substitution for mammalian genes, the rate of amino acid substitution of a protein is determined by its amino acid composition. The content of glycine is shown to correlate strongly and negatively with the rate of substitution. Empirical formulae, called indices of mutability, are developed in order to predict the rate of molecular evolution of a protein from data on its amino acid sequence. (4) Studies on the evolutionary patterns of electrophoretic mobility of proteins. A theoretical model was constructed that predicts the electric charge of a protein at any given pH and its isoelectric point from data on its primary and quaternary structures. Using this model, the evolutionary change in electrophoretic mobilities of different proteins and the expected amount of electrophoretically hidden genetic variation were studied. In the absence of selection for the pI value, proteins will on the average evolve toward a mildly basic pI. (Abstract shortened with permission of author.) ^

A Jewel in Our Midst: a photo essay of the Connecticut River

Its unique tidal marshes, ecology, geology, scenic areas, and fascinating history make the Connecticut River a treasure to residents and visitors alike. It is one of the 1,713 “Wetlands of International Importance” designated throughout the world by the International Ramsar Convention. This photo essay also describes the education efforts underway by Connecticut Sea Grant and its partners to assist educators with resource materials.

Improving Automaticity with Basic Addition Facts: Do Taped Problems Work Faster Than Cover, Copy, Compare?

This small pilot study compared the effectiveness of two interventions to improve automaticity with basic addition facts: Taped Problems (TP) and Cover, Copy, Compare (CCC), in students aged 6-10. Automaticity was measured using Mathematics Curriculum-Based Measurement (M-CBM) at pretest, after 10 days, and after 20 days of intervention. Our hypothesis was that the TP group will gain higher levels of automaticity more quickly than the CCC and control groups. However, when gain scores were compared, no significant differences were found between groups. Limitations to the study include low treatment integrity and a short duration of intervention.

Metodología de la enseñanza y formación del profesorado : El caso de la Sección Pedagógica y la Facultad de Ciencias de la Educación de la Universidad Nacional de La Plata entre 1906 y 1920

En este trabajo investigamos la Metodología de la enseñanza como asignatura y como habilidad del desempeño profesional en la formación inicial de los profesores en la Sección Pedagógica entre 1906 y 1914, y en la Facultad de Ciencias de la Educación entre 1914 y 1920, ambas en la Universidad Nacional de La Plata. Dicha formación se gestó y desarrolló en el marco de un proyecto fundacional integral para nuestra Universidad. Estudiamos desde una perspectiva curricular la formación inicial de los profesores, es decir, aquella instancia institucional y formal de preparación para el ejercicio de la docencia. Aparecen en un segundo plano de importancia referencias al ejercicio profesional en tanto algunas prescripciones pedagógicas y didácticas resultaban también recomendadas para los docentes ya recibidos. Recurrimos al análisis de documentos. Tomamos como universo de análisis las Revistas Archivos de Pedagogía y Ciencias Afines y Archivos de Ciencias de la Educación que, en tanto órgano de difusión de las instituciones mencionadas, nos aportaron valiosos elementos para la reconstrucción de los trayectos formativos de los profesorados y para conocer ciertas características generales adjudicadas a la Metodología de la enseñanza. También utilizamos escritos de Víctor Mercante y otros de Joaquín V. González, quienes fueron referentes claves en la concreción de la formación de docentes en nuestra Universidad. Visualizamos la presencia de un sustento positivista tiñendo diferentes dimensiones formativas: la secuencia y organización de las asignaturas del curriculum, en las que predominaría una supremacía de la teoría sobre la práctica; la exigencia de complementar las lecciones teóricas con instancias de observación y experimentación; las constantes y dominantes manifestaciones sobre la principalidad de la ciencia. Además, a partir del estudio de los programas de "Metodología general" y "Metodología especial" como asignaturas del curriculum, y de la concepción de Mercante sobre éstas, pudimos inferir una confianza depositada en que un buen uso de la Metodología de la enseñanza facilitaría un desempeño profesional eficaz. En el interjuego permanente entre el marco conceptual-referencial y el material empírico, construimos dos ejes a partir de los cuales analizar esa Metodología de enseñanza. El primero es de carácter curricular e incluye, por un lado, entenderla como asignatura del curriculum de la formación de profesores y, por el otro, como una habilidad profesional conformando parte de las intencionalidades formativas de éste. El segundo eje se arma entendiendo a la Metodología de enseñanza como una habilidad del profesional docente que facilita el desempeño en el aula, y a esta habilidad como un lugar reservado para la normatividad del saber pedagógico. Esta mirada histórica sobre los orígenes de la formación docente en nuestra Casa de Estudios, pretende aportar elementos para la reflexión curricular actual sobre la formación de formadores. A su vez, en un segundo plano, nos interesa destacar la presencia y características de un espacio de normatividad/prescripción propio del saber pedagógico de la época. En los debates didácticos actuales, cobra relevancia la conformación de ese componente normativo/prescriptivo, por lo que consideramos que la perspectiva de estudio aquí propuesta nos aporta elementos para enriquecer la reflexión.

Christos C. Tsagalis. The Oral Palimsest. Exploring Intertextuality in the Homeric Epics. Center for Hellenic Studies, Harvard University Press, Cambridge, Massachusetts, and London, England, 2008, ix+325 pp.

Fil: Zecchin de Fasano, Graciela Cristina. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Metodología de la enseñanza y formación del profesorado : El caso de la Sección Pedagógica y la Facultad de Ciencias de la Educación de la Universidad Nacional de La Plata entre 1906 y 1920

En este trabajo investigamos la Metodología de la enseñanza como asignatura y como habilidad del desempeño profesional en la formación inicial de los profesores en la Sección Pedagógica entre 1906 y 1914, y en la Facultad de Ciencias de la Educación entre 1914 y 1920, ambas en la Universidad Nacional de La Plata. Dicha formación se gestó y desarrolló en el marco de un proyecto fundacional integral para nuestra Universidad. Estudiamos desde una perspectiva curricular la formación inicial de los profesores, es decir, aquella instancia institucional y formal de preparación para el ejercicio de la docencia. Aparecen en un segundo plano de importancia referencias al ejercicio profesional en tanto algunas prescripciones pedagógicas y didácticas resultaban también recomendadas para los docentes ya recibidos. Recurrimos al análisis de documentos. Tomamos como universo de análisis las Revistas Archivos de Pedagogía y Ciencias Afines y Archivos de Ciencias de la Educación que, en tanto órgano de difusión de las instituciones mencionadas, nos aportaron valiosos elementos para la reconstrucción de los trayectos formativos de los profesorados y para conocer ciertas características generales adjudicadas a la Metodología de la enseñanza. También utilizamos escritos de Víctor Mercante y otros de Joaquín V. González, quienes fueron referentes claves en la concreción de la formación de docentes en nuestra Universidad. Visualizamos la presencia de un sustento positivista tiñendo diferentes dimensiones formativas: la secuencia y organización de las asignaturas del curriculum, en las que predominaría una supremacía de la teoría sobre la práctica; la exigencia de complementar las lecciones teóricas con instancias de observación y experimentación; las constantes y dominantes manifestaciones sobre la principalidad de la ciencia. Además, a partir del estudio de los programas de "Metodología general" y "Metodología especial" como asignaturas del curriculum, y de la concepción de Mercante sobre éstas, pudimos inferir una confianza depositada en que un buen uso de la Metodología de la enseñanza facilitaría un desempeño profesional eficaz. En el interjuego permanente entre el marco conceptual-referencial y el material empírico, construimos dos ejes a partir de los cuales analizar esa Metodología de enseñanza. El primero es de carácter curricular e incluye, por un lado, entenderla como asignatura del curriculum de la formación de profesores y, por el otro, como una habilidad profesional conformando parte de las intencionalidades formativas de éste. El segundo eje se arma entendiendo a la Metodología de enseñanza como una habilidad del profesional docente que facilita el desempeño en el aula, y a esta habilidad como un lugar reservado para la normatividad del saber pedagógico. Esta mirada histórica sobre los orígenes de la formación docente en nuestra Casa de Estudios, pretende aportar elementos para la reflexión curricular actual sobre la formación de formadores. A su vez, en un segundo plano, nos interesa destacar la presencia y características de un espacio de normatividad/prescripción propio del saber pedagógico de la época. En los debates didácticos actuales, cobra relevancia la conformación de ese componente normativo/prescriptivo, por lo que consideramos que la perspectiva de estudio aquí propuesta nos aporta elementos para enriquecer la reflexión.