5,656 research outputs found

    Problemas Actuales de Política Educacional en Chile, indagando en tiempo. Investigación Documental. ¿ Qué refleja el actual sistema de evalucación docente, como politica educativa, de la democracia chilena?

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    Trabajo presentado en la cátedra Política y Gestión Educacional en Chile, Magíster en política y gestión Educacional.Vivimos en una sociedad que ve a las formas evaluativas como parte de la realidad diaria. Dentro de este ámbito, la Evaluación Docente debería ser una más entre tantas, por lo que no tendría que llamar la atención más de lo que es en sí misma; sin embargo esto no sucede, puesto que no ha quedado lo suficientemente claro el tipo de evaluación que es, su finalidad como fortalecimiento, por una parte, de la profesión docente y por otra, su influencia directa, pero no exclusiva, en la calidad de la educación. No se debe dejar de lado su origen, el cual se gesta en un modelo de Democracia tan singular como lo es el modelo neoliberal de nuestra democracia, que pareciera tener más ribetes de una democracia más bien técnica, que una de carácter participativo. Bajo esta mirada, la Política de la Evaluación Docente se puede definir bajo dos ámbitos evaluativos: el democrático versus el tecno-evaluativo

    Diversity of Decline-Rate-Corrected Type Ia Supernova Rise Times: One Mode or Two?

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    B-band light-curve rise times for eight unusually well-observed nearby Type Ia supernovae (SNe) are fitted by a newly developed template-building algorithm, using light-curve functions that are smooth, flexible, and free of potential bias from externally derived templates and other prior assumptions. From the available literature, photometric BVRI data collected over many months, including the earliest points, are reconciled, combined, and fitted to a unique time of explosion for each SN. On average, after they are corrected for light-curve decline rate, three SNe rise in 18.81 +- 0.36 days, while five SNe rise in 16.64 +- 0.21 days. If all eight SNe are sampled from a single parent population (a hypothesis not favored by statistical tests), the rms intrinsic scatter of the decline-rate-corrected SN rise time is 0.96 +0.52 -0.25 days -- a first measurement of this dispersion. The corresponding global mean rise time is 17.44 +- 0.39 days, where the uncertainty is dominated by intrinsic variance. This value is ~2 days shorter than two published averages that nominally are twice as precise, though also based on small samples. When comparing high-z to low-z SN luminosities for determining cosmological parameters, bias can be introduced by use of a light-curve template with an unrealistic rise time. If the period over which light curves are sampled depends on z in a manner typical of current search and measurement strategies, a two-day discrepancy in template rise time can bias the luminosity comparison by ~0.03 magnitudes.Comment: As accepted by The Astrophysical Journal; 15 pages, 6 figures, 2 tables. Explanatory material rearranged and enhanced; Fig. 4 reformatte

    Bioreceptive interfaces for biophilic urban resilience

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    The emerging field of Biodesign sees living organisms as embedded in the design process to create bio-generated materials and artefacts. To support the growth and maintenance of these organisms, designers can adopt a Bioreceptive Design (BD) approach, recently defined as a design approach occurring every time materials or artefacts are intentionally designed to be colonized by life forms. Through this approach, the inert counterpart undergoes specific studies to reach the best bioreceptive potential for the designated life form, also considering the environment in which the artifact will be placed. In urban environments, BD examples tackle vegetation to create greener spaces and provide phytoremediation for better air quality and biodiversity in the built environment, in the wider view of nature-based solutions and climatic transitions of cities. This study addresses the possibility of developing bioreceptive interfaces for mosses and lichens to respond to biophilic and regenerative sustainability needs in urban contexts. These organisms have contributed as pioneers, during the evolution of life on our Planet, in the formation and regulation of soil and atmosphere; moreover, they are currently used in biomonitoring actions, also contributing to the environmental awareness of the built environment. The paper proposes BD as a design approach of mutual interest, aiming at responding to the host needs and preferable environmental conditions, serving multiple species that act as co-authors of an open-ended design, increasing urban biodiversity, and providing resilient, restorative, and regenerative environments. In particular, we present some of the results of an interdisciplinary research through design, born from the collaboration between design and biology, aiming both to bring sustainable and innovative solutions for the Biodesign and architecture sectors, but also to positively affect biological activities of biomonitoring and citizen awareness. From the design perspective, BD is applied for the selection of those material features that match the needs of the selected organism (e.g., porosity, color). Moreover, the use of Computational Design has played a crucial role in designing and prototyping bioinspired, organic shapes and textures. From a biological perspective, the research compares different methodologies for the bio-colonization of artefacts to obtain the best results for the timing and survival of the organisms. The prototypes were therefore exposed open-air with no protection or superficial treatments in a highly colonized area (from mosses and lichens), favoring the attachment of spores and propagules on the surfaces. On the other hand, some prototypes were used to test the transplant of the organisms as an alternative and faster possibility, also suitable for interior design. This study points out how BD can be applicable when designing for the living, making clear the designer’s possibilities for adopting this approach: ranging from material design to biomimicry, designing for not-only-human users, considering the host’s needs and preferable growth conditions, adopting a multispecies design approach while suggesting new relationships among biotic and abiotic agents. The paper highlights how BD can provide sustainable, low-maintenance, and regenerative nature-based solutions to foster resilient urban environments

    First Impressions: Early-Time Classification of Supernovae using Host Galaxy Information and Shallow Learning

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    Substantial effort has been devoted to the characterization of transient phenomena from photometric information. Automated approaches to this problem have taken advantage of complete phase-coverage of an event, limiting their use for triggering rapid follow-up of ongoing phenomena. In this work, we introduce a neural network with a single recurrent layer designed explicitly for early photometric classification of supernovae. Our algorithm leverages transfer learning to account for model misspecification, host galaxy photometry to solve the data scarcity problem soon after discovery, and a custom weighted loss to prioritize accurate early classification. We first train our algorithm using state-of-the-art transient and host galaxy simulations, then adapt its weights and validate it on the spectroscopically-confirmed SNe Ia, SNe II, and SNe Ib/c from the Zwicky Transient Facility Bright Transient Survey. On observed data, our method achieves an overall accuracy of 82±282 \pm 2% within 3 days of an event's discovery, and an accuracy of 87±587 \pm 5% within 30 days of discovery. At both early and late phases, our method achieves comparable or superior results to the leading classification algorithms with a simpler network architecture. These results help pave the way for rapid photometric and spectroscopic follow-up of scientifically-valuable transients discovered in massive synoptic surveys.Comment: 24 pages, 8 figures. Accepted to Ap

    The Rise Time of Type Ia Supernovae from the Supernova Legacy Survey

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    We compare the rise times of nearby and distant Type Ia supernovae (SNe Ia) as a test for evolution using 73 high-redshift spectroscopically-confirmed SNe Ia from the first two years of the five year Supernova Legacy Survey (SNLS) and published observations of nearby SN. Because of the ``rolling'' search nature of the SNLS, our measurement is approximately 6 times more precise than previous studies, allowing for a more sensitive test of evolution between nearby and distant supernovae. Adopting a simple t2t^2 early-time model (as in previous studies), we find that the rest-frame BB rise times for a fiducial SN Ia at high and low redshift are consistent, with values 19.10−0.17+0.18(stat)±0.2(syst)19.10^{+0.18}_{-0.17}({stat}) \pm 0.2 ({syst}) and 19.58−0.19+0.2219.58^{+0.22}_{-0.19} days, respectively; the statistical significance of this difference is only 1.4 \sg . The errors represent the uncertainty in the mean rather than any variation between individual SN. We also compare subsets of our high-redshift data set based on decline rate, host galaxy star formation rate, and redshift, finding no substantive evidence for any subsample dependence.Comment: Accepted for publication in AJ; minor changes (spelling and grammatical) to conform with published versio

    Abundance stratification in Type Ia Supernovae - II: The rapidly declining, spectroscopically normal SN 2004eo

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    The variation of properties of Type Ia supernovae, the thermonuclear explosions of Chandrasekhar-mass carbon-oxygen white dwarfs, is caused by different nucleosynthetic outcomes of these explosions, which can be traced from the distribution of abundances in the ejecta. The composition stratification of the spectroscopically normal but rapidly declining SN2004eo is studied performing spectrum synthesis of a time-series of spectra obtained before and after maximum, and of one nebular spectrum obtained about eight months later. Early-time spectra indicate that the outer ejecta are dominated by oxygen and silicon, and contain other intermediate-mass elements (IME), implying that the outer part of the star was subject only to partial burning. In the inner part, nuclear statistical equilibrium (NSE) material dominates, but the production of 56Ni was limited to ~0.43 \pm 0.05 Msun. An innermost zone containing ~0.25 Msun of stable Fe-group material is also present. The relatively small amount of NSE material synthesised by SN2004eo explains both the dimness and the rapidly evolving light curve of this SN.Comment: 12 pages, 7 figures. Accepted for publication in MNRA

    Type Ia supernova SN 2003du: optical observations

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    UBVRI photometry and optical spectra of type Ia supernova SN 2003du obtained at the Indian Astronomical Observatory for nearly a year since discovery are presented. The apparent magnitude at maximum was B=13.53 +/- 0.02 mag, and the colour (B-V) = -0.08 +/- 0.03 mag. The luminosity decline rate, Delta(m_{15}(B)) = 1.04 +/- 0.04 mag indicates an absolute B magnitude at maximum of M_B = -19.34 +/- 0.3 mag and the distance modulus to the parent galaxy as mu=32.89 +/- 0.4.The light curve shapes are similar, though not identical, to those of SNe 1998bu and 1990N, both of which had luminosity decline rates similar to that of SN 2003du and occurred in spiral galaxies. The peak bolometric luminosity indicates that 0.9 Msun mass of 56Ni was ejected by the supernova. The spectral evolution and the evolution of the Si II and Ca II absorption velocities closely follows that of SN 1998bu, and in general, is within the scatter of the velocities observed in normal type Ia supernovae. The spectroscopic and photometric behaviour of SN 2003du is quite typical for SNe Ia in spirals. A high velocity absorption component in the Ca II (H & K) and IR-triplet features, with absorption velocities of ~20,000 km/s and ~22,000 km/s respectively, is detected in the pre-maximum spectra of days -11 and -7.Comment: 10 pages, 10 figures; Accepted for publication in A&

    Optical and Infrared Photometry of the Unusual Type Ia Supernova 2000cx

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    We present optical and infrared photometry of the unusual Type Ia supernova 2000cx. With the data of Li et al. (2001) and Jha (2002), this comprises the largest dataset ever assembled for a Type Ia SN, more than 600 points in UBVRIJHK. We confirm the finding of Li et al. regarding the unusually blue B-V colors as SN 2000cx entered the nebular phase. Its I-band secondary hump was extremely weak given its B-band decline rate. The V minus near infrared colors likewise do not match loci based on other slowly declining Type Ia SNe, though V-K is the least ``abnormal''. In several ways SN 2000cx resembles other slow decliners, given its B-band decline rate (Delta m_15(B) = 0.93), the appearance of Fe III lines and weakness of Si II in its pre-maximum spectrum, the V-K colors and post-maximum V-H colors. If the distance modulus derived from Surface Brightness Fluctuations of the host galaxy is correct, we find that the rate of light increase prior to maximum, the characteristics of the bolometric light curve, and the implied absolute magnitude at maximum are all consistent with a sub-luminous object with Delta m_15(B) ~ 1.6-1.7 having a higher than normal kinetic energy.Comment: 46 pages, 17 figures, to be published in Publications of the Astronomical Society of the Pacifi
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