3,755 research outputs found
Adaptive reuse of Libre software systems for supporting on-line collaboration
In this paper, the adaptive reuse of Plone; an open source content management system is described. In one instance, Plone has been used as the backbone of a collaboration and communication support infrastructure within a large research project. In the other, Plone has been used as the main web-presence of a specialist group of the British Computer Society. This paper analyses the benefits and problems of reusing Plone to support collaboration. Based on this reuse experience, a more systematic approach to supporting Plone reuse is proposed. This approach takes into account the special case of reuse support relevant to open source software developments
Static dielectric response of icosahedral fullerenes from C60 to C2160 by an all electron density functional theory
The static dielectric response of C60, C180, C240, C540, C720, C960, C1500,
and C2160 fullerenes is characterized by an all-electron density-functional
method. First, the screened polarizabilities of C60, C180, C240, and C540, are
determined by the finite-field method using Gaussian basis set containing 35
basis functions per atom. In the second set of calculations, the unscreened
polarizabilities are calculated for fullerenes C60 through C2160 from the
self-consistent Kohn-Sham orbitals and eigen-values using the sum-over-states
method. The approximate screened polarizabilities, obtained by applying a
correction determined within linear response theory show excellent agreement
with the finite-field polarizabilities. The static dipole polarizability per
atom in C2160 is (4 Angstrom^3) three times larger than that in C60 (1.344
Angstrom^3). Our results reduce the uncertainty in various theoretical models
used previously to describe the dielectric response of fullerenes and show that
quantum size effects in polarizability are significantly smaller than
previously thought.Comment: RevTex, 3 figure
Using open source tools to support collaboration within CALIBRE
Abstract – This paper describes the deployment of Plone, an
Open-Source content management system, to support the
activities of CALIBRE, an EU-funded coordination action
integrating research into Libre software. The criteria by
which Plone was selected are described, and the goodness of
fit to these criteria is analysed.
As a coordination action, CALIBRE involves 12 partners
with different requirements and characteristics. The
CALIBRE Working Environment (CWE) must therefore
support a variety of users with different levels of technical expertise and expectations.
Implementation of the support infrastructure for CALIBRE
is ongoing, and has provided some interesting insights into the benefits of the use of libre software. Although Plone has not been explicitly developed as a collaboration infrastructure, with its wealth of plugins, it has proven highly adaptable for this purpose
Self-Regulation of Breathing as a Primary Treatment for Anxiety
Understanding the autonomic nervous system and homeostatic changes associated with emotions remains a major challenge for neuroscientists and a fundamental prerequisite to treat anxiety, stress, and emotional disorders. Based on recent publications, the inter-relationship
between respiration and emotions and the influence of respiration on autonomic changes, and subsequent widespread membrane potential changes resulting from changes in homeostasis are discussed. We hypothesize that reversing homeostatic alterations with meditation and breathing techniques rather than targeting neurotransmitters with medication may be a superior method to address the whole body changes that occur in stress, anxiety, and depression. Detrimental effects of stress, negative emotions, and
sympathetic dominance of the autonomic nervous system have been shown to be counteracted by different forms of meditation, relaxation, and breathing techniques. We propose that these breathing techniques could be used as firstline and supplemental treatments for stress, anxiety, depression, and some emotional disorders
Electronic structure, vibrational stability, infra-red, and Raman spectra of B24N24 cages
We examine the vibrational stability of three candidate structures for the
B24N24 cage and report their infra-red (IR) and Raman spectra. The candidate
structures considered are a round cage with octahedral O symmetry, a cage with
S_4 symmetry that satisfies the isolated square rule, and a cage of S_8
symmetry, which combines the caps of the (4,4) nanotube, and contains two extra
squares and octagons. The calculations are performed within density functional
theory, at the all electron level, with large basis sets, and within the
generalized gradient approximation. The vertical ionization potential (VIP) and
static dipole polarizability are also reported. The
S_4 and S_8 cages are energetically nearly degenerate and are favored over
the O cage which has six extra octagons and squares. The IR and Raman spectra
of the three clusters show notable differences providing thereby a way to
identify and possibly synthesize the cages.Comment: (Uses Elsevier style file; To appear in Chemical Physics Letters
The limitations of Slater's element-dependent exchange functional from analytic density functional theory
Our recent formulation of the analytic and variational Slater-Roothaan (SR)
method, which uses Gaussian basis sets to variationally express the molecular
orbitals, electron density and the one body effective potential of density
functional theory, is reviewed. Variational fitting can be extended to the
resolution of identity method,where variationality then refers to the error in
each two electron integral and not to the total energy. It is proposed that the
appropriate fitting functions be charge neutral and that all ab initio energies
be evaluated using two-center fits of the two-electron integrals. The SR method
has its root in the Slater's Xalpha method and permits an arbitrary scaling of
the Slater-Gaspar-Kohn-Sham exchange-correlation potential around each atom in
the system. Of several ways of choosing the scaling factors (Slater's exchange
parameters), two most obvious are the Hartree-Fock (HF), alpha_HF, values and
the exact atomic, alpha_EA, values. The performance of this simple analytic
model with both sets for atomization energies of G2 set of 148 molecules is
better than the local density approximation or the HF theory, although the
errors in atomization energy are larger than the target chemical accuracy.
To improve peformance for atomization energies, the SR method is
reparametrized to give atomization energies of 148 molecules to be comparbale
to those obtained by one of the most widely used generalized gradient
approximations. The mean absolute error in ionization potentials of 49 atoms
and molecules is about 0.5 eV and that in bond distances of 27 molecules is
about 0.02 Angstrom. The overall good performance of the computationally
efficient SR method using any reasonable set of alpha values makes it a
promising method for study of large systems.Comment: 33 pages, Uses RevTex, to appear in The Journal of Chemical Physic
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