24,595 research outputs found
Monochromatic Clique Decompositions of Graphs
Let be a graph whose edges are coloured with colours, and be a -tuple of graphs. A monochromatic -decomposition of is a partition of the edge set of such that each
part is either a single edge or forms a monochromatic copy of in colour
, for some . Let be the smallest
number , such that, for every order- graph and every
-edge-colouring, there is a monochromatic -decomposition with at
most elements. Extending the previous results of Liu and Sousa
["Monochromatic -decompositions of graphs", Journal of Graph Theory},
76:89--100, 2014], we solve this problem when each graph in is a
clique and is sufficiently large.Comment: 14 pages; to appear in J Graph Theor
Modelling a layer for real-time management of interactions in web based distance learning
In the last few years, the University of Aveiro, Portugal, has been offering several distance learning courses
over the Web, using e-learning platforms.
Experience showed that different editions of a same course, using the same contents and structure, and having
similar target learners, had different success rates. What would be the reason for that?
A hypothesis was considered: The level of success could be directly related with the remote follow-up of the
learners’ participation in the courses; the best results usually occur when the follow-up is closer.
The existing e-learning platforms offer and the standardization works being developed by organizations and
consortiums like IMS (IMS Global Learning Consortium, Inc), ADL SCORM (Advanced Distributed Learning
Sherable Content Object Reference Model), IEEE LTSC LOM (Institute of Electrical and Electronic Engineers
Learning Technologies Standard Committee Learning Object Metadata), ARIADNE (ARIADNE Foundation
for the European Knowledge Pool), AICC CMI (Aviation Industry CBT Committee Computer Managed
Instruction), etc, don’t cover the course monitorization concerns mentioned. Those projects were focused on
aspects like contents and its delivery in the context of the execution of the courses’ activities. This is even
true in the SCORM project that doesn’t include any reference to the management of the e-learning processes.
Recently, in the context of the IMS Global Consortium, a new project designated IMS LD (Learning Design) is
under development, providing a framework for the description of learning units under a three level model. In
the most recently defined level, the C level, some functionalities related to notifications were proposed,
expressing similar concerns to the ones that triggered our research. However, the extent at which IMS LD
takes the functionalities is, from our point of view, not complete.
This article describes a proposal of a reference model and functionalities towards a specification of a layer for
real-time management of user interactions on LMSs, and its possible integration with the ADL SCORM
standard proposal. The paper includes a discussion of the management metadata model for the LMS
sub-system and how the integration of the management module under SCORM may be achieved
Enhancing web supported learning in higher education by adding a management layer to LMSs
There are many situations in the e-Learning experiences
that can compromise the success of the courses. Many
times simple reasons are great enough to motivate people
to abandon them. For example, if someone does not
execute a programmed activity inside the defined window
of time, it can compromise the rest of the course to that
person. In such situations it would be important that the
teacher knew about the situation in useful time, to be able
to take any corrective action.
Another example could be presented, involving the
professor and the learners. Let us assume that an activity
A2 is programmed to be executed by the learners and that
it depends on the previous knowledge of the result of the
evaluation of a work submitted by the learners to the
teacher (activity A1). If the teacher doesn’t inform the
learners about their classification in useful time, that can
compromise the execution of the activity A2.
It seems to be necessary to use mechanisms of automatic
management, in real time, of the envolvement of each
participant in a distance learning course using LMS
(Learning Management System). Such a functionality
allows the detection of deviations to the scheduled
activities planned for each actor. If it is the case, the
referred mechanism can initiate the process of sending
notifications to the relevant entities, enabling the
correction of these deviations.
Several organizations and consortiuns, involving the
industry, governmental institutions and universities, are
developing projects of standardization. It seemed
important to us to see how the referred aspects were
covered by those projects, and to perceive how it could be
possible to articulate our work with the ones that are
available from these organizations and consortiuns.
This article describes the work that the authors are
developing towards the specification of a layer for
real-time management of user interactions with LMSs,
during the operationalization of a course, and also
includes a management meta-data model, related to that
management layer
The importance of target audiences in the design of training actions
This paper describes the process of definition, conceptualization and implementation of a business course addressed for logistic and industrial managers. This course was designed using a blended methodology, with training in classroom, visits to enterprises and self- study, supported by an eLearning platform. The aim of this work is to create an opportunity to reflect about the decisions and strategies implemented and point future developments
Site-dependent hydrogenation on graphdiyne
Graphene is one of the most important materials in science today due to its
unique and remarkable electronic, thermal and mechanical properties. However in
its pristine state, graphene is a gapless semiconductor, what limits its use in
transistor electronics. In part due to the revolution created by graphene in
materials science, there is a renewed interest in other possible graphene-like
two-dimensional structures. Examples of these structures are graphynes and
graphdiynes, which are two-dimensional structures, composed of carbon atoms in
sp2 and sp-hybridized states. Graphdiynes (benzenoid rings connecting two
acetylenic groups) were recently synthesized and some of them are intrinsically
nonzero gap systems. These systems can be easily hydrogenated and the relative
level of hydrogenation can be used to tune the band gap values. We have
investigated, using fully reactive molecular dynamics (ReaxFF), the structural
and dynamics aspects of the hydrogenation mechanisms of graphdiyne membranes.
Our results showed that the hydrogen bindings have different atom incorporation
rates and that the hydrogenation patterns change in time in a very complex way.
The formation of correlated domains reported to hydrogenated graphene is no
longer observed in graphdiyne cases.Comment: Submitted to Carbo
On the functional form of the metallicity-giant planet correlation
It is generally accepted that the presence of a giant planet is strongly
dependent on the stellar metallicity. A stellar mass dependence has also been
investigated, but this dependence does not seem as strong as the metallicity
dependence. Even for metallicity, however, the exact form of the correlation
has not been established. In this paper, we test several scenarios for
describing the frequency of giant planets as a function of its host parameters.
We perform this test on two volume-limited samples (from CORALIE and HARPS). By
using a Bayesian analysis, we quantitatively compared the different scenarios.
We confirm that giant planet frequency is indeed a function of metallicity.
However, there is no statistical difference between a constant or an
exponential function for stars with subsolar metallicities contrary to what has
been previously stated in the literature. The dependence on stellar mass could
neither be confirmed nor be discarded.Comment: 5 pages, 2 figures, accepted in A&
Wealth Effects in Emerging Market Economies
We build a panel of 14 emerging economies to estimate the magnitude of housing, stock market, and money wealth effects on consumption. Using modern panel data econometric techniques and quarterly data for the period 1990/1-2008/2, we show that; (i) wealth effects are statistically significant and relatively large in magnitude; (ii) housing wealth effects tend to be smaller for Asian emerging markets while stock markets wealth effects are, in general, smaller for Latin American countries; (iii) housing wealth effects have increased for Asian countries in recent years; and (iv) consumption reacts stronger to negative than to positive shocks in housing and financial wealth.wealth effects, consumption, emerging markets.
Quantum theory of spectral diffusion induced electron spin decoherence
A quantum cluster expansion method is developed for the problem of localized
electron spin decoherence due to dipolar fluctuations of lattice nuclear spins.
At the lowest order it provides a microscopic explanation for the Lorentzian
diffusion of Hahn echoes without resorting to any phenomenological Markovian
assumption. Our numerical results show remarkable agreement with recent
electron spin echo experiments in phosphorus doped silicon.Comment: 5 pages, 1 figur
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