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Striving against invalidity in qualitative research: Discussing a reflective framework
The aim of this paper is to discuss a reflective validation framework related with the study of teaching approaches, teaching styles or teaching orientations of university academics. In the recent years, and particularly since the eighties, there have been a growing number of investigations linking teaching conceptions with teaching practices. The majority of investigations dealing with university teachers’ conceptions and practices draw their conclusions based on indirect observation, since data gathering involves mainly semi-structured interviews or the application of questionnaires and inventories. Therefore ‘only-half-the-story’ has been reported. The presented validation framework has a five-part three-stage structure and was built upon earlier work (Selvaruby, O’Sullivan, & Watts, 2007). In this model validity is conceptualized as an ‘iterative-interactive-process’, therefore integrating a set of specific strategies envisaging the maximization of scientific quality. The application of the model is illustrated by using it for the discussion of a longitudinal study involving the investigation of the relationship between questioning practices and Trigwell and co-workers’ concept of preferential teaching approaches (Trigwell, Prosser & Taylor, 1994). Field work of this naturalistic-interpretative research was conducted during two academic years (2009/2010 and 2010/2011) and implied close collaboration with a group of four university teachers lecturing biology to undergraduates.This work was financed by Fundação para a Ciência e a Tecnologia (SFRH/BD/44611/2008) and by Fundos FEDER através do Programa Operacional Fatores de Competitividade – COMPETE e por Fundos Nacionais através da FCT (PTDC/CPE-CED/117516/2010)
Morphology of galaxies with quiescent recent assembly history in a Lambda-CDM universe
The standard disc formation scenario postulates that disc forms as the gas
cools and flows into the centre of the dark matter halo, conserving the
specific angular momentum. Major mergers have been shown to be able to destroy
or highly perturb the disc components. More recently, the alignment of the
material that is accreted to form the galaxy has been pointed out as a key
ingredient to determine galaxy morphology. However, in a hierarchical scenario
galaxy formation is a complex process that combines these processes and others
in a non-linear way so that the origin of galaxy morphology remains to be fully
understood. We aim at exploring the differences in the formation histories of
galaxies with a variety of morphology, but quite recent merger histories, to
identify which mechanisms are playing a major role. We analyse when minor
mergers can be considered relevant to determine galaxy morphology. We also
study the specific angular momentum content of the disc and central spheroidal
components separately. We used cosmological hydrodynamical simulations that
include an effective, physically motivated supernova feedback that is able to
regulate the star formation in haloes of different masses. We analysed the
morphology and formation history of a sample of 15 galaxies of a cosmological
simulation. We performed a spheroid-disc decomposition of the selected galaxies
and their progenitor systems. The angular momentum orientation of the merging
systems as well as their relative masses were estimated to analyse the role
played by orientation and by minor mergers in the determination of the
morphology. We found the discs to be formed by conserving the specific angular
momentum in accordance with the classical disc formation model. The specific
angular momentum of the stellar central spheroid correlates with the dark
matter halo angular momentum and determines a power law. AbridgedComment: 10 pages, 9 figures, A&A in pres
The gas metallicity gradient and the star formation activity of disc galaxies
We study oxygen abundance profiles of the gaseous disc components in
simulated galaxies in a hierarchical universe. We analyse the disc metallicity
gradients in relation to the stellar masses and star formation rates of the
simulated galaxies. We find a trend for galaxies with low stellar masses to
have steeper metallicity gradients than galaxies with high stellar masses at z
~0. We also detect that the gas-phase metallicity slopes and the specific star
formation rate (sSFR) of our simulated disc galaxies are consistent with
recently reported observations at z ~0. Simulated galaxies with high stellar
masses reproduce the observed relationship at all analysed redshifts and have
an increasing contribution of discs with positive metallicity slopes with
increasing redshift. Simulated galaxies with low stellar masses a have larger
fraction of negative metallicity gradients with increasing redshift. Simulated
galaxies with positive or very negative metallicity slopes exhibit disturbed
morphologies and/or have a close neighbour. We analyse the evolution of the
slope of the oxygen profile and sSFR for a gas-rich galaxy-galaxy encounter,
finding that this kind of events could generate either positive and negative
gas-phase oxygen profiles depending on their state of evolution. Our results
support claims that the determination of reliable metallicity gradients as a
function of redshift is a key piece of information to understand galaxy
formation and set constrains on the subgrid physics.Comment: 12 pages, 8 figures, accepted MNRA
Contexts for questioning: Two zones of teaching and learning in undergraduate science
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ Springer Science+Business Media B.V. 2012.Higher education institutions are currently undertaking a challenging process in moving from teacher-orientated to student-focused approaches. Students’ ability to asking questions is fundamental to developing critical reasoning, and to the process of scientific enquiry itself. Our premise is that questioning competences should become a central focus of current reforms in higher education. This study, part of a broader naturalistic research project, aims at developing a theoretical framework for conceptualizing different contexts for questioning, illustrating the application of the proposed framework (contextual questioning zones) and reflecting about some of the dimensions of teaching and learning, for overcoming some of the challenges that higher education institutions are facing presently. The discussion of two ‘opposite’ contexts of enquiry is based on qualitative data, gathered through close collaboration with four teachers of undergraduate biology at a Portuguese university. These teachers were observed during their ‘daily activity’ during an academic year. Data was also gathered by interviewing these teachers and 8 selected students, at the end of the year, and used to sustain the argumentation. The paper concludes with some reflections and suggestions to promote authentic enquiry-based learning experiences.Portuguese Fundação para a Ciência e a Tecnologi
On the mass assembly of low-mass galaxies in hydrodynamical simulations of structure formation
Cosmological hydrodynamical simulations are studied in order to analyse
generic trends for the stellar, baryonic and halo mass assembly of low-mass
galaxies (M_* < 3 x 10^10 M_sun) as a function of their present halo mass, in
the context of the Lambda-CDM scenario and common subgrid physics schemes. We
obtain that smaller galaxies exhibit higher specific star formation rates and
higher gas fractions. Although these trends are in rough agreement with
observations, the absolute values of these quantities tend to be lower than
observed ones since z~2. The simulated galaxy stellar mass fraction increases
with halo mass, consistently with semi-empirical inferences. However, the
predicted correlation between them shows negligible variations up to high z,
while these inferences seem to indicate some evolution. The hot gas mass in z=0
halos is higher than the central galaxy mass by a factor of ~1-1.5 and this
factor increases up to ~5-7 at z~2 for the smallest galaxies. The stellar,
baryonic and halo evolutionary tracks of simulated galaxies show that smaller
galaxies tend to delay their baryonic and stellar mass assembly with respect to
the halo one. The Supernova feedback treatment included in this model plays a
key role on this behaviour albeit the trend is still weaker than the one
inferred from observations. At z>2, the overall properties of simulated
galaxies are not in large disagreement with those derived from observations.Comment: 19 pages, 12 figures. Accepted for publication in MNRAS: 6th August
2013. First submitted: 7th July 201
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