7,904 research outputs found
Information Literacy Instruction for Upper-Year Undergraduate Students: A Stratified Course-Integrated Approach
Undergraduate students face many potential barriers to learning about the process of conducting research. Information literacy instruction provided through faculty-librarian collaboration in an effort to expand the abilities of the “novice researcher” can ease the experience of undergraduate students. In addition, information literacy instruction may invoke increased student participation in the scholarly discourse of their chosen discipline. The implementation of a stratified course-integrated approach may be particularly valuable to upper-level undergraduates in preparation for completing a thesis or other culminating project in their final year of study. This claim is examined within the context of an instruction session observed as a component of a third-year undergraduate Materials Science and Engineering course
Solar Twins and Possible Solutions of the Solar and Jupiter Abundance Problems
Implications of the recently discovered systematic abundance difference
between the Sun and two collections of `solar twins' are discussed. The
differences can be understood as an imprint on the abundances of the solar
convection zone caused by the lock-up of heavy elements in the planets. Such a
scenario also leads naturally to possible solutions of two other abundance
peculiarities; 1) the discrepancy between photospheric abundances derived from
accurate 3-D models of the solar photosphere and the abundance of heavy
elements in the solar interior deduced from helioseismology, and 2) the
abundance pattern of Jupiter, which can either--with great difficulty--be
interpreted as a general and similar overabundance of both common elements such
as carbon, nitrogen and sulphur and rare inert gases such as argon, krypton and
xenon, or--much more simply--as an under-abundance of hydrogen.Comment: 4 pages, submitted to ApJL, v2 has improved formatting of reference
lis
Perceived Constraints and Opportunities for Brazilian Smallholders Going Organic: a case of coffee in the state of Minas Gerais
This paper presents the findings of an analysis of the perceived rationales of smallholders for declining or entering organically certified coffee production, in the case Poço Fundo region, Minas Gerais. Based on group interviews and questionnaires, the rationale for farmers who declined organic production were found to be avoidance of perceived risk of harvest failure associated with the process of convertion from conventional to organic coffee production. Rationales for farmers who entered organic production included non-market benefits such as environmental quality and life quality enhancement
Dis-embedded Openness: Inequalities in European Economic Integration at the Sectoral Level
The process of European integration resulted in a marked increase in
transnational economic flows, yet regional inequalities along many
developmental indicators remain. We analyze the unevenness of European
economies with respect to the embedding of export sectors in upstream domestic
flows, and their dependency on dominant export partners. We use the WIOD data
set of sectoral flows for the period of 1995-2011 for 24 European countries. We
found that East European economies were significantly more likely to experience
increasing unevenness and dependency with increasing openness, while core
countries of Europe managed to decrease their unevenness while increasing their
openness. Nevertheless, by analyzing the trajectories of changes for each
country, we see that East European countries are also experiencing a turning
point, either switching to a path similar to the core, or to a retrograde path
with decreasing openness. We analyze our data using pooled time series models
and case studies of country trajectories
The observable prestellar phase of the IMF
The observed similarities between the mass function of prestellar cores (CMF)
and the stellar initial mass function (IMF) have led to the suggestion that the
IMF is already largely determined in the gas phase. However, theoretical
arguments show that the CMF may differ significantly from the IMF. In this
Letter, we study the relation between the CMF and the IMF, as predicted by the
IMF model of Padoan and Nordlund. We show that 1) the observed mass of
prestellar cores is on average a few times smaller than that of the stellar
systems they generate; 2) the CMF rises monotonically with decreasing mass,
with a noticeable change in slope at approximately 3-5 solar masses, depending
on mean density; 3) the selection of cores with masses larger than half their
Bonnor-Ebert mass yields a CMF approximately consistent with the system IMF,
rescaled in mass by the same factor as our model IMF, and therefore suitable to
estimate the local efficiency of star formation, and to study the dependence of
the IMF peak on cloud properties; 4) only one in five pre-brown-dwarf core
candidates is a true progenitor to a brown dwarf.Comment: ApJ Letters, accepte
3D non-LTE line formation in the solar photosphere and the solar oxygen abundance
We study the formation of O I and OH spectral lines in three-dimensional
hydrodynamic models of the solar photosphere. The line source function of the O
I 777 nm triplet is allowed to depart from local thermodynamic equilibrium
(LTE), within the two-level-atom approximation. Comparison with results from 1D
models show that the 3D models alleviate, but do not remove, the discrepancy
between the oxygen abundances reported from non-LTE work on the 777 nm triplet
and from the [O I] 630 nm and OH lines. Results for the latter two could imply
that the solar oxygen abundance is below 8.8 (lg(H) = 12). If this is
confirmed, the discrepancy between theory and observation for the 777 nm
triplet lines might fall within the range of errors in equivalent width
measurements and f-values. The line source function of the 777 nm triplet in
the 1.5D approximation is shown to differ insignificantly from the full 3D
non-LTE result.Comment: 10 pages, uuencoded compressed PostScript file including figures, to
appear in Astronomy & Astrophysics. Also available at
ftp://www.astro.su.se/pub/da
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