11,199 research outputs found
An Innovative University Course for Cooperating Teachers
The transformation of a course for certifying cooperating teachers in Puerto Rico is described. The course was transformed to strengthen the teaching of science and mathematics and to make the course more congruent with the educational principles of constructivism promoted by the CETP projects at the national level, including Puerto Rico. The 45-hour requirement was distributed over nine days. The Open Space strategy was modified to include multiple active teaching-learning and assessment techniques, which promoted a learning environment based on trust, dedication, and the commitment of all participants to learn and help each other learn. Even more relevant was the fact that more content was covered and in more depth. The modified version of the course was offered to secondary level science and mathematics teachers, especially to teachers who work at the practicum centers that are part of the PR-CETP
Equation of state of hadronic matter with dibaryons in an effective quark model
The equation of state of symmetric nuclear matter with the inclusion of
non-strange dibaryons is studied. We pay special attention to the existence of
a dibaryon condensate at zero temperature. These calculations have been
performed in an extended quark-meson coupling model with density-dependent
parameters, which takes into account the finite size of nucleons and dibaryons.
A first-order phase-transition to pure dibaryon matter has been found. The
corresponding critical density is strongly dependent on the value of the
dibaryon mass. The density behavior of the nucleon and dibaryon effective
masses and confining volumes have also been discussed.Comment: 9 pages, LaTex, 3 Postscript figures, a misprint correcte
An 80 pc Long Massive Molecular Filament in the Galactic Mid-Plane
The ubiquity of filaments in star forming regions on a range of scales is
clear, yet their role in the star formation process remains in question. We
suggest that there are distinct classes of filaments which are responsible for
their observed diversity in star-forming regions. An example of a massive
molecular filament in the Galactic mid-plane formed at the intersection of
UV-driven bubbles which displays a coherent velocity structure (< 4 km/s) over
80 pc is presented. We classify such sources as Massive Molecular Filaments
(MMFs; M > 10^4 Msun, length > 10 pc, velocity gradient < 5 km/s) and suggest
that MMFs are just one of the many different classes of filaments discussed in
the literature today. Many MMFs are aligned with the Galactic Plane and may be
akin to the dark dust lanes seen in Grand Design Spirals.Comment: To appear in proceedings of the 'Labyrinth of Star Formation' meeting
(18-22 June 2012, Chania, Greece), published by Springe
AME - Asteroseismology Made Easy. Estimating stellar properties by use of scaled models
We present a new method to obtain stellar properties for stars exhibiting
solar-like oscillations in an easy, fast, and transparent way. The method,
called Asteroseismology Made Easy (AME), can determine stellar masses,
mean-densities, radii, and surface gravities, as well as estimate ages. In this
writing we present AME as a visual and powerful tool which could be useful; in
particular in the light of the large number of exoplanets being found.
AME consists of a set of figures from which the stellar parameters are
deduced. These figures are made from a grid of stellar evolutionary models that
cover masses ranging from 0.7 Msun to 1.6 Msun in steps of 0.1 Msun and
metallicities in the interval -0.3 dex <= [Fe/H] <= +0.3 dex in increments of
0.1 dex. The stellar evolutionary models are computed using the Modules for
Experiments in Stellar Astrophysics (MESA) code with simple input physics.
We have compared the results from AME with results for three groups of stars;
stars with radii determined from interferometry (and measured parallaxes),
stars with radii determined from measurements of their parallaxes (and
calculated angular diameters), and stars with results based on the modelling of
their individual oscillation frequencies. We find that a comparison of the
radii from interferometry to those from AME yield a weighted mean of the
fractional differences of just 2%. This is also the level of deviation that we
find when we compare the parallax-based radii to the radii determined from AME.
The comparison between independently determined stellar parameters and those
found using AME show that our method can provide reliable stellar masses,
radii, and ages, with median uncertainties in the order of 4%, 2%, and 25%
respectively.Comment: 18 pages, 25 figures. To be published in Astronomy & Astrophysic
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