842 research outputs found
Solitons in relativistic mean field models
Assuming that the nucleus can be treated as a perfect fluid we study the
conditions for the formation and propagation of Korteweg-de Vries (KdV)
solitons in nuclear matter. The KdV equation is obtained from the Euler and
continuity equations in nonrelativistic hydrodynamics. The existence of these
solitons depends on the nuclear equation of state, which, in our approach,
comes from well known relativistic mean field models. We reexamine early works
on nuclear solitons, replacing the old equations of state by new ones, based on
QHD and on its variants. Our analysis suggests that KdV solitons may indeed be
formed in the nucleus with a width which, in some cases, can be smaller than
one fermi.Comment: 15 pages, 1 figur
Introducing a fifth pedagogy: Experience-based strategies for facilitating learning in natural environments
Educators have identified four categories of 'productive pedagogies' that are considered to lead to authentic student engagement and learning in the classroom. This study was designed to explore and extend these pedagogies in the context of learning in natural environments, in particular, through the programmes of Queensland environmental education centres. In-depth interview and observation data were collected from students, classroom teachers and centre teachers who had participated in 12 environmental education programmes across Queensland, in order to identify the strategies that are most effective in facilitating learning in the natural environment. A fifth productive pedagogy category, 'experience-based learning', is proposed. Experience-based learning is particularly important in addressing students' environmental attitudes and actions. The implications for the delivery of environmental education programmes both within and outside the classroom are discussed
Putting theory oriented evaluation into practice
Evaluations of gaming simulations and business games as teaching devices are typically end-state driven. This emphasis fails to detect how the simulation being evaluated does or does not bring about its desired consequences. This paper advances the use of a logic model approach which possesses a holistic perspective that aims at including all elements associated with the situation created by a game. The use of the logic model approach is illustrated as applied to Simgame, a board game created for secondary school level business education in six European Union countries
Developing construction graduates fit for the 4th industrial revolution through fieldwork application of active learning
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Problem-based learning approaches in meteorology
Problem-Based Learning, despite recent controversies about its effectiveness, is used extensively as a teaching method throughout higher education. In meteorology, there has been little attempt to incorporate Problem-Based Learning techniques into the curriculum. Motivated by a desire to enhance the reflective engagement of students within a current field course module, this project describes the implementation of two test Problem-Based Learning activities and testing and improvement using several different and complementary means of evaluation. By the end of a 2-year program of design, implementation, testing, and reflection and re-evaluation, two robust, engaging activities have been developed that provide an enhanced and diverse learning environment in the field course. The results suggest that Problem-Based Learning techniques would be a useful addition to the meteorology curriculum and suggestions for courses and activities that may benefit from this approach are included in the conclusions
Supernova Bounds on Majoron-emitting decays of light neutrinos
Neutrino masses arising from the spontaneous violation of ungauged
lepton-number are accompanied by a physical Goldstone boson, generically called
Majoron. In the high-density supernova medium the effects of Majoron-emitting
neutrino decays are important even if they are suppressed in vacuo by small
neutrino masses and/or small off-diagonal couplings. We reconsider the
influence of these decays on the neutrino signal of supernovae in the light of
recent Super-Kamiokande data on solar and atmospheric neutrinos. We find that
majoron-neutrino coupling constants in the range 3\times 10^{-7}\lsim g\lsim
2\times 10^{-5} or g \gsim 3 \times 10^{-4} are excluded by the observation
of SN1987A. Then we discuss the potential of Superkamiokande and the Sudbury
Neutrino Observatory to detect majoron neutrino interactions in the case of a
future galactic supernova. We find that these experiments could probe majoron
neutrino interactions with improved sensitivity.Comment: 28 pages, 5 figure
Assisted Inflation from Geometric Tachyon
We study the effect of rolling of N D3-branes in the vicinity of NS5-branes.
We find out that this system coupled with the four dimensional gravity gives
the slow roll assisted inflation of the scalar field theory. Once again this
expectation is exactly similar to that of N-tachyon assisted inflation on
unstable D-branes.Comment: 15 pages, 3 figures, minor modifications, to appear in JHE
Non-minimally Coupled Tachyonic Inflation in Warped String Background
We show that the non-minimal coupling of tachyon field to the scalar
curvature, as proposed by Piao et al, with the chosen coupling parameter does
not produce the effective potential where the tachyon field can roll down from
T=0 to large along the slope of the potential. We find a correct choice of
the parameters which ensures this requirement and support slow-roll inflation.
However, we find that the cosmological parameter found from the analysis of the
theory are not in the range obtained from observations. We then invoke warped
compactification and varying dilaton field over the compact manifold, as
proposed by Raeymaekers, to show that in such a setup the observed parameter
space can be ensured.Comment: minor typos corrected and references adde
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