Améliorer les apprentissages en sciences en milieu francophone minoritaire : résultats de l’expérimentation d’un modèle pédagogique

Selon les postulats théoriques, les faibles résultats scolaires chez les populations linguistiques minoritaires s’expliqueraient par des facteurs socioculturels et économiques, on recommande donc une pédagogie qui composerait avec ces éléments. Dans le cadre de cette recherche, les auteurs ont créé et expérimenté un modèle pédagogique pour enseigner les sciences en milieu minoritaire tenant compte de ces facteurs. Lors d’une intervention de deux mois, des élèves de cinquième année ont étudié les marais salés à partir de ce modèle pédagogique. L’expression écrite et orale de leurs observations demeurait une priorité. Les résultats ont révélé une attitude positive envers l’approche, un apprentissage scientifique important et une progression lexicale aux niveaux oral et écrit.Socio-cultural and economic factors may in part explain poor academic results for linguistic minorities. In such a case, pedagogical considerations in light of such factors should be put in place. This research created and experimented a pedagogical model for teaching science to minority language students, while considering socio-cultural factors. During a two-month intervention, grade five students studied salt-water marshes in a unit conceived within this model. Oral and written expression of their observations constituted an important part of the experiment. Results indicate a favourable attitude towards the pedagogical approach and progression in science and lexical learning in both written and oral language.Los postulados teóricos indican que los bajos resultados escolares en las poblaciones de lenguas minoritarias se justifican por factores socioculturales y económicos. Por lo tanto, se requiere de una pedagogía que tome en cuenta estos elementos. En el marco de esta investigación, los autores han creado y experimentado un modelo pedagógico para enseñar las ciencias en un ámbito minoritario tomando en cuenta estos factores. En una intervención de una duración de dos meses, alumnos de quinto grado estudiaron las marismas saladas a partir de un modelo pedagógico. Quedó prioritaria la expresión escrita y oral de sus observaciones. Los resultados revelaron una actitud positiva hacia el enfoque, un aprendizaje científico importante así como una progresión lexical a nivel oral y escrito

Infrared luminosities and aromatic features in the 24 μm flux-limited sample of 5muses

We study a 24 μm selected sample of 330 galaxies observed with the infrared spectrograph for the 5 mJy Unbiased Spitzer Extragalactic Survey. We estimate accurate total infrared luminosities by combining mid-IR spectroscopy and mid-to-far infrared photometry, and by utilizing newempirical spectral templates from Spitzer data. The infrared luminosities of this sample range mostly from 10^9 L_⊙ to 10^(13.5) L_⊙,with 83% in the range 10^(10) L_⊙ < L_(IR) < 10^(12) L_⊙. The redshifts range from 0.008 to 4.27, with a median of 0.144. The equivalent widths of the 6.2 μm aromatic feature have a bimodal distribution, probably related to selection effects. We use the 6.2μm polycyclic aromatic hydrocarbon equivalent width (PAH EW) to classify our objects as starburst (SB)-dominated (44%), SB-AGN composite (22%), and active galactic nucleus (AGN)-dominated (34%). The high EW objects (SB-dominated) tend to have steeper mid-IR to far-IR spectral slopes and lower L_(IR) and redshifts. The low EW objects (AGN-dominated) tend to have less steep spectral slopes and higher L_(IR) and redshifts. This dichotomy leads to a gross correlation between EW and slope, which does not hold within either group. AGN-dominated sources tend to have lower log(L_(PAH7.7 μm)/L_(PAH11.3 μm)) ratios than star-forming galaxies, possibly due to preferential destruction of the smaller aromatics by the AGN. The log(L_(PAH7.7 μm)/L_(PAH11.3 μm)) ratios for star-forming galaxies are lower in our sample than the ratios measured from the nuclear spectra of nearby normal galaxies, most probably indicating a difference in the ionization state or grain size distribution between the nuclear regions and the entire galaxy. Finally, we provide a calibration relating the monochromatic continuum or aromatic feature luminosity to L_(IR) for different types of objects

Millimeter-Wave Line Ratios and Sub-beam Volume Density Distributions

We explore the use of mm-wave emission line ratios to trace molecular gas density when observations integrate over a wide range of volume densities within a single telescope beam. For observations targeting external galaxies, this case is unavoidable. Using a framework similar to that of Krumholz and Thompson (2007), we model emission for a set of common extragalactic lines from lognormal and power law density distributions. We consider the median density of gas producing emission and the ability to predict density variations from observed line ratios. We emphasize line ratio variations, because these do not require knowing the absolute abundance of our tracers. Patterns of line ratio variations have the prospect to illuminate the high-end shape of the density distribution, and to capture changes in the dense gas fraction and median volume density. Our results with and without a high density power law tail differ appreciably; we highlight better knowledge of the PDF shape as an important area. We also show the implications of sub-beam density distributions for isotopologue studies targeting dense gas tracers. Differential excitation often implies a significant correction to the naive case. We provide tabulated versions of many of our results, which can be used to interpret changes in mm-wave line ratios in terms of changes in the underlying density distributions.Comment: 24 pages, 16 figure, Accepted for publication in the Astrophysical Journal, two online tables temporarily available at http://www.astronomy.ohio-state.edu/~leroy.42/densegas_table2.txt and http://www.astronomy.ohio-state.edu/~leroy.42/densegas_table3.tx

Les rapports préoccupants des futurs enseignants avec les milieux physiques et numériques

Les futurs enseignants, dont plusieurs sont des natifs numériques, se distinguent des générations précédentes par leur manière de vivre et de travailler. L'utilisation des TIC contribue-t-elle à les distancer du milieu physique ? Sont-ils engagés dans l'action environnementale ? Notre étude visait à comprendre les rapports des futurs enseignants avec les milieux physiques et numériques. L'analyse des entrevues menées avec des étudiants en formation des maîtres, à Montréal et à Moncton, montre que les futurs enseignants entretiennent une relation discontinue avec le milieu naturel. Ils sont toutefois conscients que la nature leur procure calme, ressourcement et beauté. Fréquenté souvent, le milieu numérique leur offre distraction, affiliation sociale, information personnalisée, rapidité d’exécution et connexion avec un monde planétaire. Les futurs enseignants interrogés sont peu engagés en matière d’environnement. La recherche montre la nécessité de favoriser les rapports des futurs enseignants avec leur milieu de vie, à l'aide d'activités de terrain, de façon à les inciter à mieux connaître, apprécier et améliorer leur communauté écologique et sociale.Future teachers among whom many are digital natives, can be distinguished from preceding generations by their way of life and work. Does the use of ICT contribute in distancing them from the physical environment ? Are they involved in environmental action ? Our study aimed at understanding the relationships future teachers have with the physical and digital environments. The analysis of interviews conducted with pre-service teachers in Montreal and in Moncton shows that future teachers have a fragmented relationship with the natural environment. However, they are aware that nature provides them calmness, rejuvenation and beauty. Often visited, the digital environment offers them distraction, social affiliation, personalised information, quick execution and connection with the global world. The interviewed future teachers have few committment to the environment. The research shows the necessity to promote future teachers’ relationships with their living environment with the help of outdoor activities in order to encourage them to better know, appreciate and improve their ecological and social community

ALMA Resolves 30 Doradus: Sub-parsec Molecular Cloud Structure Near the Closest Super-Star Cluster

We present ALMA observations of 30 Doradus -- the highest resolution view of molecular gas in an extragalactic star formation region to date (~0.4pc x 0.6pc). The 30Dor-10 cloud north of R136 was mapped in 12CO 2-1, 13CO 2-1, C18O 2-1, 1.3mm continuum, the H30alpha recombination line, and two H2CO 3-2 transitions. Most 12CO emission is associated with small filaments and clumps (<1pc, ~1000 Msun at the current resolution). Some clumps are associated with protostars, including "pillars of creation" photoablated by intense radiation from R136. Emission from molecular clouds is often analyzed by decomposition into approximately beam-sized clumps. Such clumps in 30 Doradus follow similar trends in size, linewidth, and surface density to Milky Way clumps. The 30 Doradus clumps have somewhat larger linewidths for a given size than predicted by Larson's scaling relation, consistent with pressure confinement. They extend to higher surface density at a given size and linewidth compared to clouds studied at 10pc resolution. These trends are also true of clumps in Galactic infrared-dark clouds; higher resolution observations of both environments are required. Consistency of clump masses calculated from dust continuum, CO, and the virial theorem reveals that the CO abundance in 30 Doradus clumps is not significantly different from the LMC mean, but the dust abundance may be reduced by ~2. There are no strong trends in clump properties with distance from R136; dense clumps are not strongly affected by the external radiation field, but there is a modest trend towards lower dense clump filling fraction deeper in the cloud.Comment: accepted to Ap

The Relationship Between Molecular Gas, HI, and Star Formation in the Low-Mass, Low-Metallicity Magellanic Clouds

The Magellanic Clouds provide the only laboratory to study the effect of metallicity and galaxy mass on molecular gas and star formation at high (~20 pc) resolution. We use the dust emission from HERITAGE Herschel data to map the molecular gas in the Magellanic Clouds, avoiding the known biases of CO emission as a tracer of H$_{2}$. Using our dust-based molecular gas estimates, we find molecular gas depletion times of ~0.4 Gyr in the LMC and ~0.6 SMC at 1 kpc scales. These depletion times fall within the range found for normal disk galaxies, but are shorter than the average value, which could be due to recent bursts in star formation. We find no evidence for a strong intrinsic dependence of the molecular gas depletion time on metallicity. We study the relationship between gas and star formation rate across a range in size scales from 20 pc to ~1 kpc, including how the scatter in molecular gas depletion time changes with size scale, and discuss the physical mechanisms driving the relationships. We compare the metallicity-dependent star formation models of Ostriker, McKee, and Leroy (2010) and Krumholz (2013) to our observations and find that they both predict the trend in the data, suggesting that the inclusion of a diffuse neutral medium is important at lower metallicity.Comment: 24 pages, 14 figures, accepted for publication in ApJ. FITS files of the dust-based estimates of the H2 column densities for the LMC and SMC (shown in Figures 2 and 3) will be available online through Ap

Strengthening Developmental Education Reforms: Evidence on Implementation Efforts From the Scaling Innovation Project

In this paper, the authors draw on empirical data from the Community College Research Center’s Scaling Innovation project to examine trends in developmental education instructional reform and outline a framework for reform adoption and adaptation. The paper’s findings are based on two qualitative data sources: a scan of developmental education reforms that involved changes to curricula, course structure, and/or pedagogy; and fieldwork conducted at 11 colleges working to replicate highpotential instructional innovations developed at other colleges. The data suggest that colleges tend to enact developmental education reforms in ways that may unintentionally undermine their potential benefits. The authors present a framework for engaging practitioners in activities that will increase the impact of their developmental education reforms while strengthening institutional capacity

Gas-phase metallicity profiles of the Bluedisk galaxies: Is metallicity in a local star formation regulated equilibrium?

As part of the Bluedisk survey, we analyse the radial gas-phase metallicity profiles of 50 late-type galaxies. We compare the metallicity profiles of a sample of H I-rich galaxies against a control sample of H I-`normal' galaxies. We find the metallicity gradient of a galaxy to be strongly correlated with its H I mass fraction (M(H I) / M_{*}). We note that some galaxies exhibit a steeper metallicity profile in the outer disc than in the inner disc. These galaxies are found in both the H I-rich and control samples. This contradicts a previous indication that these outer drops are exclusive to H I-rich galaxies. These effects are not driven by bars, although we do find some indication that barred galaxies have flatter metallicity profiles. By applying a simple analytical model, we are able to account for the variety of metallicity profiles that the two samples present. The success of this model implies that the metallicity in these isolated galaxies may be in a local equilibrium, regulated by star formation. This insight could provide an explanation of the observed local mass-metallicity relation