Las propuestas de conocimiento escolar : entre el conocimiento científico y el escolar

Se presentan algunos resultados de tres estudios de caso en los que se analizan consideraciones sobre el conocimiento científico como referente en la elaboración y desarrollo de las propuestas de conocimiento escolar en las clases de ciencias, así como la relación con otros posibles referentes. El análisis de las entrevistas realizadas a profesores de ciencias, de la unidad didáctica por ellos diseñada y la grabación audiovisual del desarrollo de las clases, permiten establecer posibles relaciones entre las declaraciones de los profesores sobre el conocimiento científico y las propuestas de conocimiento escolar. Los resultados permiten señalar la necesidad de analizar las particularidades epistemológicas sobre el conocimiento escolar, se plantean tres niveles diferentes en la constitución del conocimiento escolar

Synthesis and Characterization of LnAg(WO4)(MoO4)

Polycrystalline LnAg(WO4)(MoO4) powders, with Ln = La to Lu and Y, have been obtained by ceramic method. Rietveld refinement for all compounds reveals that they present tetragonal symmetry, space group I41/a (No. 88), where the Ln3+/Ag+ ions are located in the 4a atomic positions, since the W/Mo are randomly distributed into 4b crystal sites. In these compounds, a and b lattice parameters take values between those corresponding to tungstate and molybdate compounds. A progressive decrease in the lattice parameters is observed in going from La to Lu derivatives as a consequence of the well-known lanthanide contraction

Accumulation of Flavonols over Hydroxycinnamic Acids Favors Oxidative Damage Protection under Abiotic Stress

Efficient detoxification of reactive oxygen species (ROS) is thought to play a key role in enhancing the tolerance of plants to abiotic stresses. Although multiple pathways, enzymes, and antioxidants are present in plants, their exact roles during different stress responses remain unclear. Here, we report on the characterization of the different antioxidant mechanisms of tomato plants subjected to heat stress, salinity stress, or a combination of both stresses. All the treatments applied induced an increase of oxidative stress, with the salinity treatment being the most aggressive, resulting in plants with the lowest biomass, and the highest levels of H2O2 accumulation, lipid peroxidation, and protein oxidation. However, the results obtained from the transcript expression study and enzymatic activities related to the ascorbate-glutathione pathway did not fully explain the differences in the oxidative damage observed between salinity and the combination of salinity and heat. An exhaustive metabolomics study revealed the differential accumulation of phenolic compounds depending on the type of abiotic stress applied. An analysis at gene and enzyme levels of the phenylpropanoid metabolism concluded that under conditions where flavonols accumulated to a greater degree as compared to hydroxycinnamic acids, the oxidative damage was lower, highlighting the importance of flavonols as powerful antioxidants, and their role in abiotic stress tolerance.This work was supported by the Ministry of Economy and Competitiveness from Spain (GrantNo. AGL2015-66033-R), and Seneca Foundation from Region of Murcia, Spain (Grant no.15288/ PI/10).Peer reviewedPeer Reviewe

Análisis Campo-Sustancia de TRIZ para el uso de Trichoderma asperelloides como antagónico en Citrus sinensis

La teoría de solución de problemas de inventiva (TRIZ), es el resultado del análisis minucioso de patentes a nivel mundial, forma parte de un sistema de principios y algoritmos donde se amplifica la posibilidad de encontrar soluciones innovadoras a problemas científicos, superando la inercia psicológica basada en paradigmas. El presente trabajo propone un análisis biológico utilizando la herramienta analítica TRIZ con el uso del Análisis Campo-Sustancia (Su-Field) originalmente destinado a resolver problemas de ingeniería para determinar el efecto antagónico de Trichoderma asperelloides frente a Fusarium, patógeno presentado en plantas de cítricos encontrando como el resultado final ideal el uso de T. asperelloides como agente de control patógeno en plantas de cítricos (Citrus sinensis) en el norte de Veracruz, México

The U(1)-Higgs Model: Critical Behaviour in the Confinig-Higgs region

We study numerically the critical properties of the U(1)-Higgs lattice model, with fixed Higgs modulus, in the region of small gauge coupling where the Higgs and Confining phases merge. We find evidence of a first order transition line that ends in a second order point. By means of a rotation in parameter space we introduce thermodynamic magnitudes and critical exponents in close resemblance with simple models that show analogous critical behaviour. The measured data allow us to fit the critical exponents finding values in agreement with the mean field prediction. The location of the critical point and the slope of the first order line are accurately given.Comment: 21 text pages. 12 postscript figures available on reques

Una propuesta de enseñanza de didáctica general y didáctica especial en la formación inicial de profesores de biología (Córdoba, Argentina)

La profesionalidad docente puede considerarse como uno de los aspectos característicos de las tendencias actuales en el campo de la didáctica y de la educación (Camilloni, 2016). De hecho, una de las preocupaciones de la gestión universitaria en Argentina está centrada más que nunca en transformar la formación de los profesores para la educación secundaria (Rasetto, 2012). De hecho, una de las preocupaciones de la gestión universitaria en Argentina está centrada más que nunca en transformar la formación de los profesores para la educación secundaria, recuperando la centralidad de la enseñanza como eje de la actividad profesional, la articulación teoría-práctica, la investigación educativa, la contextualización en los distintos ámbitos de intervención docente, así como también, los fundamentos éticos y el compromiso social de la tarea educativa (Rasetto, 2012). En esta ponencia relatamos la génesis y algunas experiencias que emergen del desarrollo de una propuesta de trabajo en las cátedras de Didáctica General (DG) y Didáctica Especial (DE) del quinto y sexto semestre, respectivamente, de la carrera de Profesorado en Ciencias Biológicas en la Universidad Nacional de Córdoba, Argentina. Con ello, nos proponemos no sólo dar sentido a nuestros posicionamientos epistemológicos, ideológicos, teórico-metodológicos -lo que abordaremos a continuación-, sino también, seguidamente, recuperar la reflexión a partir de la experiencia (Larrosa, 2006) como profesores de DG y DE

Measurement of the prompt J/ψ and ψ(2S) polarizations in pp collisions at √s=7 TeV

This article is published Open Access at sciencedirect.com. It is distributed under the terms of the Creative Commons Attribution License 3.0.-- et al.The polarizations of prompt J/ψ and ψ(2S) mesons are measured in proton-proton collisions at √s=7 TeV, using a dimuon data sample collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.9 fb-1. The prompt J/ψ and ψ(2S) polarization parameters λθ{symbol}, λφ, and λθ{symbol}φ, as well as the frame-invariant quantity λ~, are measured from the dimuon decay angular distributions in three different polarization frames. The J/ψ results are obtained in the transverse momentum range 14<pT<70 GeV, in the rapidity intervals |y|<0.6 and 0.6<|y|<1.2. The corresponding ψ(2S) results cover 14<pT<50 GeV and include a third rapidity bin, 1.2<|y|<1.5. No evidence of large polarizations is seen in these kinematic regions, which extend much beyond those previously explored. © 2013 CERN.We acknowledge the support for the funding agencies: BMWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MEYS (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Republic of Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEPCenter, IPST and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA). Individuals have received support from the Marie-Curie programme and the European Research Council and EPLANET (European Union); the Leventis Foundation; the A. P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of Czech Republic; the Council of Science and Industrial Research, India; the Compagnia di San Paolo (Torino); the HOMING PLUS programme of Foundation for Polish Science, cofinanced by EU, Regional Development Fund; and the Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF.Peer Reviewe

Electron-phonon renormalization of the absorption edge of the cuprous halides

Compared to most tetrahedral semiconductors, the temperature dependence of the absorption edges of the cuprous halides (CuCl, CuBr, CuI) is very small. CuCl and CuBr show a small increase of the gap $E_0$ with increasing temperature, with a change in the slope of $E_0$ vs. $T$ at around 150 K: above this temperature, the variation of $E_0$ with $T$ becomes even smaller. This unusual behavior has been clarified for CuCl by measurements of the low temperature gap vs. the isotopic masses of both constituents, yielding an anomalous negative shift with increasing copper mass. Here we report the isotope effects of Cu and Br on the gap of CuBr, and that of Cu on the gap of CuI. The measured isotope effects allow us to understand the corresponding temperature dependences, which we also report, to our knowledge for the first time, in the case of CuI. These results enable us to develop a more quantitative understanding of the phenomena mentioned for the three halides, and to interpret other anomalies reported for the temperature dependence of the absorption gap in copper and silver chalcogenides; similarities to the behavior observed for the copper chalcopyrites are also pointed out.Comment: 14 pages, 5 figures, submitted to Phys. Rev.