4,964 research outputs found
Pranab Kumar Sen: Life and works
In this article, we describe briefly the highlights and various
accomplishments in the personal as well as the academic life of Professor
Pranab Kumar Sen.Comment: Published in at http://dx.doi.org/10.1214/193940307000000013 the IMS
Collections (http://www.imstat.org/publications/imscollections.htm) by the
Institute of Mathematical Statistics (http://www.imstat.org
Description of nuclear systems with a self-consistent configuration-mixing approach. I: Theory, algorithm, and application to the C test nucleus
Although self-consistent multi-configuration methods have been used for
decades to address the description of atomic and molecular many-body systems,
only a few trials have been made in the context of nuclear structure. This work
aims at the development of such an approach to describe in a unified way
various types of correlations in nuclei, in a self-consistent manner where the
mean-field is improved as correlations are introduced. The goal is to reconcile
the usually set apart Shell-Model and Self-Consistent Mean-Field methods. This
approach is referred as "variational multiparticle-multihole configuration
mixing method". It is based on a double variational principle which yields a
set of two coupled equations that determine at the same time the expansion
coefficients of the many-body wave function and the single particle states. The
formalism is derived and discussed in a general context, starting from a
three-body Hamiltonian. Links to existing many-body techniques such as the
formalism of Green's functions are established. First applications are done
using the two-body D1S Gogny effective force. The numerical procedure is tested
on the C nucleus in order to study the convergence features of the
algorithm in different contexts. Ground state properties as well as
single-particle quantities are analyzed, and the description of the first
state is examined. This study allows to validate our numerical algorithm and
leads to encouraging results. In order to test the method further, we will
realize in the second article of this series, a systematic description of more
nuclei and observables obtained by applying the newly-developed numerical
procedure with the same Gogny force. As raised in the present work,
applications of the variational multiparticle-multihole configuration mixing
method will however ultimately require the use of an extended and more
constrained Gogny force.Comment: 22 pages, 18 figures, accepted for publication in Phys. Rev. C. v2:
minor corrections and references adde
Lesson Study and Service Learning in Teacher Preparation
The aim of this paper is to share an teacher preparation experience that combines Lesson Study (LS) with a Service Learning methodology. This experience is interdisciplinary and includes three subjects from first-grade Childhood Education, carried out at University of Malaga since academic year 2014-2015.
Within this framework, our students carry out Service Learning projects for schools in our area that are designed and developed following the LS methodology. Service Learning projects go through the following phases (Puig, J., Martín, & Batlle, 2008): 1) Preparation by the teachers involved in the project; 2) Implementation, i.e. developing the project with the students; 3) Evaluation.
The implementation phase also has three sub-phases: preparation, implementation, and round-up. It is here that the LS is developed through the following phases (Soto & Pérez, 2015): 1. Define the problem; 2. Co-operatively design an experimental lesson and its observation process; 3. First experimental lesson; 4. Analyse and review the lesson; 5. Second experimental lesson; 6. Analysis and drafting of conclusions; 7. Presentation in extended context.
We were able to gather evidence on how students teachers resolved different cognitive conflicts during the process. We saw how the LS process, with its phases and cooperative work, allows them to combine creativity and unique talents in a common project that acquires meaning and relevance thanks to Service Learning. This provides a framework that facilitates the construction of solid structures related to the meaning of the educational process, and which can be used to recalibrate what it means to be a Childhood School teacher: a creative, relevant, complex experience that requires recreating the knowledge and experience that students bring with them to the University about what it means to be a Childhood School teacher.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
12CO and 13CO J=3-2 observations toward N11 in the Large Magellanic Cloud
After 30 Doradus, N11 is the second largest and brightest nebula in the LMC.
This large nebula has several OB associations with bright nebulae at its
surroundings. N11 was previously mapped at the lowest rotational transitions of
CO (J=1--0 and 2--1), and in some particular regions pointings of the
CO J=1--0 and 2--1 lines were also performed. Using ASTE we mapped the
whole extension of the N11 nebula in the CO J=3--2 line, and three
sub-regions in the CO J=3--2 line. The regions mapped in the CO
J=3--2 were selected based on that they may be exposed to the radiation at
different ways: a region lying over the nebula related to the OB association
LH10 (N11B), another one that it is associated with the southern part of the
nebula related to the OB association LH13 (N11D), and finally a farther area at
the southwest without any embedded OB association (N11I). We found that the
morphology of the molecular clouds lying in each region shows some signatures
that could be explained by the expansion of the nebulae and the action of the
radiation. Fragmentation generated in a molecular shell due to the expansion of
the N11 nebula is suggested. The integrated line ratios CO/CO
show evidences of selective photodissociation of the CO, and probably
other mechanisms such as chemical fractionation. The CO contribution to the
continuum at 870 m was directly derived. The distribution of the
integrated line ratios CO J=3--2/2--1 show hints of stellar feedback in
N11B and N11D. The ratio between the virial and LTE mass (M/M) is higher than unity in all analyzed molecular clumps, which suggests
that the clumps are not gravitationally bounded and may be supported by
external pressure. A non-LTE analysis suggests that we are mapping gas with
densities about a few 10 cm.Comment: Accepted to be published in A&A. Figures were degrade
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Integration with Ontologies
One of today’s hottest IT topics is integration, as bringing together information from different sources and structures is not completely solved. The approach outlined here wants to illustrate how ontologies [Gr93] could help to support the integration process
Kinematic study of planetary nebulae in NGC 6822
By measuring precise radial velocities of planetary nebulae (which belong to
the intermediate age population), H II regions, and A-type supergiant stars
(which are members of the young population) in NGC 6822, we aim to determine if
both types of population share the kinematics of the disk of H I found in this
galaxy.
Spectroscopic data for four planetary nebulae were obtained with the high
spectral resolution spectrograph Magellan Inamori Kyocera Echelle (MIKE) on the
Magellan telescope at Las Campanas Observatory. Data for other three PNe and
one H II region were obtained from the SPM Catalog of Extragalactic Planetary
Nebulae which employed the Manchester Echelle Spectrometer attached to the 2.1m
telescope at the Observatorio Astron\'omico Nacional, M\'exico. In the
wavelength calibrated spectra, the heliocentric radial velocities were measured
with a precision better than 5-6 km s. Data for three additional H II
regions and a couple of A-type supergiant stars were collected from the
literature. The heliocentric radial velocities of the different objects were
compared to the velocities of the H i disk at the same position.
From the analysis of radial velocities it is found that H II regions and
A-type supergiants do share the kinematics of the H I disk at the same
position, as expected for these young objects. On the contrary, planetary
nebula velocities differ significantly from that of the H I at the same
position. The kinematics of planetary nebulae is independent from the young
population kinematics and it is closer to the behavior shown by carbon stars,
which are intermediate-age members of the stellar spheroid existing in this
galaxy. Our results are confirming that there are at least two very different
kinematical systems in NGC 6822
La educación superior en Colombia y la teoría de los costos de transacción política
This essay argues how the structure of higher education in Colombia is a reflection of a dependent organizational political contract with tenuous advances on independence. Therefore, its implementation requires higher cost in terms of political transaction compared with a contract of interdependent nature. This leads to an unequal distribution of quality and an unequal coverage, because it will favour mature institutions of higher education located in Bogotá, Medellín, Cali and Bucaramanga, over emergent institutions. Professor Peña justify normatively a new contract, and propose a policy with emphasis in connectivity, its formulation and implementation would reduce the costs of political transaction and the inequity without too much sacrifice in the efficiency.political transaction costs, public policies, higher education, organizational behaviour, interorganizational cooperation
Analyzing a Bose polaron across resonant interactions
Recently, two independent experiments reported the observation of long-lived
polarons in a Bose-Einstein condensate, providing an excellent setting to study
the generic scenario of a mobile impurity interacting with a quantum reservoir.
Here, we expand the experimental analysis by disentangling the effects of trap
inhomogeneities and the many-body continuum in one of these experiments. This
makes it possible to extract the energy of the polaron at a well-defined
density as a function of the interaction strength. Comparisons with quantum
Monte-Carlo as well as diagrammatic calculations show good agreement, and
provide a more detailed picture of the polaron properties at stronger
interactions than previously possible. Moreover, we develop a semi-classical
theory for the motional dynamics and three-body loss of the polarons, which
partly explains a previously unresolved discrepancy between theory and
experimental observations for repulsive interactions. Finally, we utilize
quantum Monte-Carlo calculations to demonstrate that the findings reported in
the two experiments are consistent with each other
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