1,084 research outputs found
Witnessed entanglement and the geometric measure of quantum discord
We establish relations between geometric quantum discord and entanglement
quantifiers obtained by means of optimal witness operators. In particular, we
prove a relation between negativity and geometric discord in the
Hilbert-Schmidt norm, which is slightly different from a previous conjectured
one [Phys. Rev. A 84, 052110 (2011)].We also show that, redefining the
geometric discord with the trace norm, better bounds can be obtained. We
illustrate our results numerically.Comment: 8 pages + 3 figures. Revised version with erratum for PRA 86, 024302
(2012). Simplified proof that discord is bounded by entanglement in any nor
Quantum state of a free spin-1/2 particle and the inextricable dependence of spin and momentum under Lorentz transformations
We revise the Dirac equation for a free particle and investigate Lorentz
transformations on spinors. We study how the spin quantization axis changes
under Lorentz transformations, and evince the interplay between spin and
momentum in this context.Comment: 14 pages, 3 figures, published as a Review in the IJQ
Portuguese Adaptation of Students Engagement in Schools International Scale (SESIS)
The importance of student’s engagement has been recently pointed out in research. However, there has been a lack of engagement assessment instrument, pertaining psychometric qualities. Objective: This paper presents the Portuguese adaptation of the “Student’s Engagement in School International Scale” (SESIS), drawn up from a12 countries international study (Lam et al., 2012; Lam et al., in press). Method: Psychometric properties of this scale were examined with data from 685 students from different grades (6th, 7th, 9th and 10th), from both sexes, and different regions of the country. Results: Factorial analysis of the results, with varimax rotation, lead to three different factors which explain 50.88% of the variance. The scale integrates the original 33 items, and cognitive, affective and behavioural dimensions. For the external validity study, the relationship between student’s engagement in school results and other school variables — academic performance, self-concept — was considered, and significant relations were observed, as expected. Conclusion: The data presented highlights the qualities of SESIS, as well as its usefulness for research purposes. Suggestion: It is suggested the investigation of the extension of SESIS’s three-dimensionality, in future studiesKeywords: Innovation, technology, research projects, etc. [Arial 10-point, justified alignment]
Extrusion compounding of polyethylene with blowing agent
Cellular plastics are very attractive for the production of lightweight, structural and/or large
dimension parts, e.g., boats, floaters, decks, etc. For their production, polymers and chemical
blowing agents are either mixed or compounded prior to processing by injection or rotational
moulding. It is essential to ensure good dispersion of the blowing agent in the polymeric matrix,
and prevent its activation from occurring during compounding, i.e., an optimal processing
window must be used. The aim of this work is to produce medium density polyethylene with
Azodicarbonamide (MDPE/ADCA) masterbatches in pellet form for further processing by
rotational moulding. For that purpose, a set of experimental procedures was conducted to
evaluate the correct processing window without premature expansion during extrusion. Upon
melt compounding of the masterbatch in pellets of different sizes, foamed parts were produced
and characterized in terms of visual aspect, expansion ability and morphology.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska Curie grant agreement No. 734205 – H2020-MSCA-RISE-201
Re-annotation of the genome sequence of Helicobacter pylori 26695
Helicobacter pylori is a pathogenic bacterium that colonizes the human epithelia, causing duodenal and gastriculcers, and gastric cancer. The genome of H. pylori 26695 has been previously sequenced and annotated. In addition, two genome-scale metabolic models have been developed. In order to maintain accurate and relevant information on coding sequences (CDS) and to retrieve new information, the assignment of new functions to Helicobacter pylori 26695s genes was performed in this work. The use of software tools, on-line databases and an annotation pipeline for inspecting each gene allowed the attribution of validated EC numbers and TC numbers to metabolic genes encoding enzymes and transport proteins, respectively. 1212 genes encoding proteins were identified in this annotation, being 712 metabolic genes and 500 non-metabolic, while 191 new functions were assignment to the CDS of this bacterium. This information provides relevant biological information for the scientific community dealing with this organism and can be used as the basis for a new metabolic model reconstruction.This work was supported by the project FCOMP-01-0124-FEDER-009707, entitled HeliSysBio molecular Systems Biology in Helicobacter pylori (Ref.: FCT PTDC/EBB-EBI/104235/2008). Daniela Correia is grateful for financial support from the FCT (PhD grant: SFRH/BD/47596/2008)
PSSA : parallel stretched simulated annealing
We consider the problem of finding all the global (and some local) minimizers of a given nonlinear optimization function (a class of problems also known as multi-local programming problems), using a novel approach based on Parallel Computing. The approach, named Parallel Stretched Simulated Annealing (PSSA), combines simulated annealing with stretching function technique, in a parallel execution environment. Our PSSA software allows to increase the resolution of the
search domains (thus facilitating the discovery of new solutions) while keeping the search time bounded. The software was
tested with a set of well known problems and some numerical results are presented
Grand canonical and canonical solution of self-avoiding walks with up to three monomers per site on the Bethe lattice
We solve a model of polymers represented by self-avoiding walks on a lattice
which may visit the same site up to three times in the grand-canonical
formalism on the Bethe lattice. This may be a model for the collapse transition
of polymers where only interactions between monomers at the same site are
considered. The phase diagram of the model is very rich, displaying coexistence
and critical surfaces, critical, critical endpoint and tricritical lines, as
well as a multicritical point. From the grand-canonical results, we present an
argument to obtain the properties of the model in the canonical ensemble, and
compare our results with simulations in the literature. We do actually find
extended and collapsed phases, but the transition between them, composed by a
line of critical endpoints and a line of tricritical points, separated by the
multicritical point, is always continuous. This result is at variance with the
simulations for the model, which suggest that part of the line should be a
discontinuous transition. Finally, we discuss the connection of the present
model with the standard model for the collapse of polymers (self-avoiding
self-attracting walks), where the transition between the extended and collapsed
phases is a tricritical point.Comment: 34 pages, including 10 figure
Integral Field Spectroscopy of the inner kpc of the elliptical galaxy NGC 5044
We used Gemini Multi-Object Spectrograph (GMOS) in the Integral Field Unit
mode to map the stellar population, emission line flux distributions and gas
kinematics in the inner kpc of NGC 5044. From the stellar populations synthesis
we found that the continuum emission is dominated by old high metallicity stars
(13 Gyr, 2.5Z). Also, its nuclear emission is diluted by a non
thermal emission, which we attribute to the presence of a weak active galactic
nuclei (AGN). In addition, we report for the first time a broad component
(FWHM 3000km) in the H emission line in the nuclear
region of NGC 5044. By using emission line ratio diagnostic diagrams we found
that two dominant ionization processes coexist, while the nuclear region (inner
200 pc) is ionized by a low luminosity AGN, the filamentary structures are
consistent with being excited by shocks. The H velocity field shows
evidence of a rotating disk, which has a velocity amplitude of
240kms at 136 pc from the nucleus. Assuming a Keplerian
approach we estimated that the mass inside this radius is
, which is in agreement with the value obtained through the
M- relation, . Modelling the
ionized gas velocity field by a rotating disk component plus inflows towards
the nucleus along filamentary structures, we obtain a mass inflow rate of
0.4 M. This inflow rate is enough to power the central AGN in NGC
5044.Comment: 16 pages, 12 figures, accepted by MNRA
- …