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

Phylogeny and molecular signatures (conserved proteins and indels) that are specific for the Bacteroidetes and Chlorobi species

<p>Abstract</p> <p>Background</p> <p>The <it>Bacteroidetes </it>and <it>Chlorobi </it>species constitute two main groups of the <it>Bacteria </it>that are closely related in phylogenetic trees. The <it>Bacteroidetes </it>species are widely distributed and include many important periodontal pathogens. In contrast, all <it>Chlorobi </it>are anoxygenic obligate photoautotrophs. Very few (or no) biochemical or molecular characteristics are known that are distinctive characteristics of these bacteria, or are commonly shared by them.</p> <p>Results</p> <p>Systematic blast searches were performed on each open reading frame in the genomes of <it>Porphyromonas gingivalis </it>W83, <it>Bacteroides fragilis </it>YCH46, <it>B. thetaiotaomicron </it>VPI-5482, <it>Gramella forsetii KT0803, Chlorobium luteolum </it>(formerly <it>Pelodictyon luteolum</it>) DSM 273 and <it>Chlorobaculum tepidum </it>(formerly <it>Chlorobium tepidum</it>) TLS to search for proteins that are uniquely present in either all or certain subgroups of <it>Bacteroidetes </it>and <it>Chlorobi</it>. These studies have identified > 600 proteins for which homologues are not found in other organisms. This includes 27 and 51 proteins that are specific for most of the sequenced <it>Bacteroidetes </it>and <it>Chlorobi </it>genomes, respectively; 52 and 38 proteins that are limited to species from the <it>Bacteroidales </it>and <it>Flavobacteriales </it>orders, respectively, and 5 proteins that are common to species from these two orders; 185 proteins that are specific for the <it>Bacteroides </it>genus. Additionally, 6 proteins that are uniquely shared by species from the <it>Bacteroidetes </it>and <it>Chlorobi </it>phyla (one of them also present in the <it>Fibrobacteres</it>) have also been identified. This work also describes two large conserved inserts in DNA polymerase III (DnaE) and alanyl-tRNA synthetase that are distinctive characteristics of the <it>Chlorobi </it>species and a 3 aa deletion in ClpB chaperone that is mainly found in various <it>Bacteroidales, Flavobacteriales </it>and <it>Flexebacteraceae</it>, but generally not found in the homologs from other organisms. Phylogenetic analyses of the <it>Bacteroidetes </it>and <it>Chlorobi </it>species is also reported based on concatenated sequences for 12 conserved proteins by different methods including the character compatibility (or clique) approach. The placement of <it>Salinibacter ruber </it>with other <it>Bacteroidetes </it>species was not resolved by other phylogenetic methods, but this affiliation was strongly supported by the character compatibility approach.</p> <p>Conclusion</p> <p>The molecular signatures described here provide novel tools for identifying and circumscribing species from the <it>Bacteroidetes </it>and <it>Chlorobi </it>phyla as well as some of their main groups in clear terms. These results also provide strong evidence that species from these two phyla (and also possibly <it>Fibrobacteres</it>) are specifically related to each other and they form a single superphylum. Functional studies on these proteins and indels should aid in the discovery of novel biochemical and physiological characteristics that are unique to these groups of bacteria.</p

Development and Longevity: Cellular and Molecular Determinants - A Mini-Review

Across species, development and longevity are tightly linked. We discuss the relevant literature and suggest that the root for this stringent relationship is the rate of development. The basis for the relationship between rate of development and longevity lies in adaptations that have occurred through evolution at multiple levels of biological complexity: organism, organ, cellular, and molecular. Thus, the analysis of the relationship is of interest for multiple fields of biology

Vespa orientalis (Hymenoptera; Vespidae), the first record in Marche region

Vespa orientalis (Hymenoptera Vespidae), prima segnalazione nella Regione Marche. Viene segnalata per la prima volta nel versante orientale della Penisola italiana, ad Ancona (Regione Marche) la presenza di Vespa orientalis Linnaeus, 1771 (Hymenoptera Vespidae). Dopo un primo avvistamento da parte di un apicoltore, sono stati effettuati dei campionamenti direttamente in apiario e l’identità degli insetti catturati è stata successivamente confermata in laboratorioThe presence of Vespa orientalis Linnaeus, 1771 (Hymenoptera Vespidae) was reported for the first time on the eastern side of the Italian peninsula, in Ancona (Marche Region). After an initial sighting by a beekeeper, sampling was carried out directly in the apiary and the identity of the insects captured was subsequently confirmed in the laborator

Retraction Note to: Magnetohydrodynamic 3D slip flow in a suspension of carbon nanotubes over a slendering sheet with heat source/sink

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Analytical modeling of MHD flow over a permeable rotating disk in the presence of soret and dufour effects: Entropy analysis.

The main concern of the present article is to study steady magnetohydrodynamics (MHD) flow, heat transfer and entropy generation past a permeable rotating disk using a semi numerical/analytical method named Homotopy Analysis Method (HAM). The results of the present study are compared with numerical quadrature solutions employing a shooting technique with excellent correlation in special cases. The entropy generation equation is derived as a function of velocity, temperature and concentration gradients. Effects of flow physical parameters including magnetic interaction parameter, suction parameter, Prandtl number, Schmidt number, Soret and Dufour number on the fluid velocity, temperature and concentration distributions as well as entropy generation number are analysed and discussed in detail. Results show that increasing the Soret number or decreasing the Dufour number tends to decrease the temperature distribution while the concentration distribution is enhanced. The averaged entropy generation number increases with increasing magnetic interaction parameter, suction parameter, Prandtl number, and Schmidt number

Temporal integration for amplitude modulation in childhood: Interaction between internal noise and memory

It is still unclear whether the gradual improvement in amplitude-modulation (AM) sensitivity typically found in children up to 10 years of age reflects an improvement in “processing efficiency” (the central ability to use information extracted by sensory mechanisms). This hypothesis was tested by evaluating temporal integration for AM, a capacity relying on memory and decision factors. This was achieved by measuring the effect of increasing the number of AM cycles (2 vs 8) on AM-detection thresholds for three groups of children aged from 5 to 11 years and a group of young adults. AM-detection thresholds were measured using a forced-choice procedure and sinusoidal AM (4 or 32 Hz rate) applied to a 1024-Hz pure-tone carrier. All age groups demonstrated temporal integration for AM at both rates; that is, significant improvements in AM sensitivity with a higher number of AM cycles. However, an effect of age is observed as both 5–6 year olds and adults exhibited more temporal integration compared to 7–8 and 10–11 year olds at both rates. This difference is due to: (i) the 5–6 year olds displaying the worst thresholds with 2 AM cycles, but similar thresholds with 8 cycles compared to the 7–8 and 10–11 year olds, and, (ii) adults showing the best thresholds with 8 AM cycles but similar thresholds with 2 cycles compared to the 7–8 and 10–11 year olds. Computational modelling indicated that higher levels of internal noise combined with poorer short-term memory capacities in children accounted for the developmental trends. Improvement in processing efficiency may therefore account for the development of AM detection in childhood

Performance Analysis of Vibrotactile and Slide-and-Squeeze Haptic Feedback Devices for Limbs Postural Adjustment

Recurrent or sustained awkward body postures are among the most frequently cited risk factors to the development of work-related musculoskeletal disorders (MSDs). To prevent workers from adopting harmful configurations but also to guide them toward more ergonomic ones, wearable haptic devices may be the ideal solution. In this paper, a vibrotactile unit, called ErgoTac, and a slide-and-squeeze unit, called CUFF, were evaluated in a limbs postural correction setting. Their capability of providing single-joint (shoulder or knee) and multi-joint (shoulder and knee at once) guidance was compared in twelve healthy subjects, using quantitative task-related metrics and subjective quantitative evaluation. An integrated environment was also built to ease communication and data sharing between the involved sensor and feedback systems. Results show good acceptability and intuitiveness for both devices. ErgoTac appeared as the suitable feedback device for the shoulder, while the CUFF may be the effective solution for the knee. This comparative study, although preliminary, was propaedeutic to the potential integration of the two devices for effective whole-body postural corrections, with the aim to develop a feedback and assistive apparatus to increase workers' awareness about risky working conditions and therefore to prevent MSDs

Measurement of the quality factor of a new low-frequency differential accelerometer for testing the equivalence principle

A cryogenic differential accelerometer has been developed to test the weak equivalence principle to a few parts in 1015 within the framework of the general relativity accuracy test in an Einstein elevator experiment. The prototype sensor was designed to identify, address, and solve the major issues associated with various aspects of the experiment. This paper illustrates the measurements conducted on this prototype sensor to attain a high quality factor (Q ∼ 105) at low frequencies (<20 Hz). Such a value is necessary for reducing the Brownian noise to match the target acceleration noise of 10−14 g/√Hz, hence providing the desired experimental accuracy.AstronomyPhysic