3,071 research outputs found
Taking over someone else's design: implications for the tutor's role in networked learning
The experience of taking over an already designed Web-based course helps us to investigate the claims in the literature about the role that tutors have more generally in networked learning. This paper addresses this issue through a case study and brings together the tutor's experience and her reflective diary, as well as the interview data from a JISC/CALT phenomenographic study of tutors' and students' experiences. This particular case study raises issues about the tutors' role, teaching activity, design and the value of content resources and knowledge representation. Finally the paper reflects on the implications for the tutor in this situation and provides suggestions for future practice
Detection of polarization from the E^4\Pi-A^4\Pi system of FeH in sunspot spectra
Here we report the first detection of polarization signals induced by the
Zeeman effect in spectral lines of the E^4\Pi-A^4\Pi system of FeH located
around 1.6 m. Motivated by the tentative detection of this band in the
intensity spectrum of late-type dwarfs, we have investigated the full Stokes
sunspot spectrum finding circular and linear polarization signatures that we
associate with the FeH lines of the E^4\Pi-A^4\Pi band system. We investigate
the Zeeman effect in these molecular transitions pointing out that in Hund's
case (a) coupling the effective Land\'e factors are never negative. For this
reason, the fact that our spectropolarimetric observations indicate that the
Land\'e factors of pairs of FeH lines have opposite signs, prompt us to
conclude that the E^4\Pi-A^4\Pi system must be in intermediate angular momentum
coupling between Hund's cases (a) and (b). We emphasize that theoretical and/or
laboratory investigations of this molecular system are urgently needed for
exploiting its promising diagnostic capabilities.Comment: 11 pages, 4 figures, accepted for publication in Astrophysical
Journal Letter
The political legitimacy of the healthcare system in Portugal: insights from the European Social Survey
This article investigates the political legitimacy of the health care system and the effects of austerity on the population’s welfare, paying particular attention to Portugal, a country severely harmed by the economic crisis. Based on analysis of data collected from the European Social Survey on 14,988 individuals living in private households during the years between 2002 and 2018, the findings of this study aim to analyze the social and political perception of citizens on the state of health services in two distinctive periods—before and after the economic crisis, according to self-interest, ideological preferences, and institutional setup as predictors of the satisfaction with the health system. The results demonstrate a negative attitude towards the health system over the years, a consistent drop during the financial crisis period, and a rapid recovery afterward. The research also shows that healthcare evaluations depend on the perceived institutional effectiveness in the citizenry’s eyes. The more the citizens perceive the government as effective and trust-worthy, the more they are satisfied with the health system. Also, differences in healthcare evaluations among social groups were felt unequally: while vulnerable citizens were more affected by the Government’s plan of austerity measures for health reform, healthcare evaluations of better-off social groups—younger individuals, those with higher incomes, higher education, and better health status—did not decline. This study contributes to the academic debate on the effects of austerity on the population’s welfare attitudes and highlights the need to examine the different impacts of reforms introduced by the crisis on social groups.info:eu-repo/semantics/publishedVersio
Penumbral thermal structure below the visible surface
. The thermal structure of the penumbra below its visible surface
(i.e., ) has important implications for our present understanding
of sunspots and their penumbrae: their brightness and energy transport, mode
conversion of magneto-acoustic waves, sunspot seismology, and so forth. .
We aim at determining the thermal stratification in the layers immediately
beneath the visible surface of the penumbra: ( km below the visible continuum-forming layer). . We analyzed
spectropolarimetric data (i.e., Stokes profiles) in three Fe \textsc{i} lines
located at 1565 nm observed with the GRIS instrument attached to the 1.5-meter
solar telescope GREGOR. The data are corrected for the smearing effects of
wide-angle scattered light and then subjected to an inversion code for the
radiative transfer equation in order to retrieve, among others, the temperature
as a function of optical depth . . We find that the
temperature gradient below the visible surface of the penumbra is smaller than
in the quiet Sun. This implies that in the region the penumbral
temperature diverges from that of the quiet Sun. The same result is obtained
when focusing only on the thermal structure below the surface of bright
penumbral filaments. We interpret these results as evidence of a thick
penumbra, whereby the magnetopause is not located near its visible surface. In
addition, we find that the temperature gradient in bright penumbral filaments
is lower than in granules. This can be explained in terms of the limited
expansion of a hot upflow inside a penumbral filament relative to a granular
upflow, as magnetic pressure and tension forces from the surrounding penumbral
magnetic field hinder an expansion like this.Comment: 5 pages; 2 figures; accepted for publication in Astronomy and
Astrophysics Letter
Uncertainties in the solar photospheric oxygen abundance
The purpose of this work is to better understand the confidence limits of the
photospheric solar oxygen abundance derived from three-dimensional models using
the forbidden [OI] line at 6300 \AA , including correlations with other
parameters involved. We worked with a three-dimensional empirical model and two
solar intensity atlases. We employed Bayesian inference as a tool to determine
the most probable value for the solar oxygen abundance given the model chosen.
We considered a number of error sources, such as uncertainties in the continuum
derivation, in the wavelength calibration and in the abundance/strength of Ni.
Our results shows correlations between the effects of several parameters
employed in the derivation. The Bayesian analysis provides robust confidence
limits taking into account all of these factors in a rigorous manner. We obtain
that, given the empirical three-dimensional model and the atlas observations
employed here, the most probable value for the solar oxygen abundance is
. However, we note that this uncertainty does
not consider possible sources of systematic errors due to the model choice.Comment: Accepted for publication in Astronomy and Astrophysic
Estimating the magnetic field strength from magnetograms
A properly calibrated longitudinal magnetograph is an instrument that
measures circular polarization and gives an estimation of the magnetic flux
density in each observed resolution element. This usually constitutes a lower
bound of the field strength in the resolution element, given that it can be
made arbitrarily large as long as it occupies a proportionally smaller area of
the resolution element and/or becomes more transversal to the observer and
still produce the same magnetic signal. Yet, we know that arbitrarily stronger
fields are less likely --hG fields are more probable than kG fields, with
fields above several kG virtually absent-- and we may even have partial
information about its angular distribution. Based on a set of sensible
considerations, we derive simple formulae based on a Bayesian analysis to give
an improved estimation of the magnetic field strength for magnetographs.Comment: 8 pages, 7 figures, accepted for publication in A&
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