4,672 research outputs found
Similarity Structure Analysis and Structural Equation Modeling in Studying Latent Structures: An Application to the Attitudes towards Portuguese Language Questionnaire
Several international studies such as PISA and PILRS (Progress in
International Reading Literacy Study), have stressed the importance of positive attitudes
and behaviours as facilitators of individuals reading literacy during the school years
and throughout their lives.
Considering that there are not available instruments for assessing attitudes Towards
Portuguese Language, it was proposed the development of the Attitudes towards
Portuguese Language Questionnaire – ATPLQ (Questionário de Atitudes Face Ã
LÃngua Portuguesa: QAFLP, Neto et al., 2011; Rebelo, 2012). The questionnaire has
22 Likert-type items, with four levels of response (Strongly Disagree, Disagree, Agree,
Strongly Agree), spread, through exploratory factor analysis (EFA), over three attitudinal
dimensions: Behavioural, Affective, and Motivational.In this study we aimed to analyse
the ATPLQ’s latent structure with a pooled sample data of 1441 participants, applying
similarity structure analysis (SSA) and confirmatory factor analysis of ordinal data
(CFA). The SSA was carried out with Hudap in order to identify the structural properties
of the questionnaire and to assess its adequacy in a Portuguese population. The CFA
was carried out with LISREL in order to assure structural validity, i.e., accounting
for factorial validity, but also for factors’ convergent and discriminant validity, and
composite reliability. These psychometric features allowed the comparison of both the
EFA derived model and the SSA derived model.
We justify the selection of the SSA’s model, and we discuss the similarities between the
results generated by SSA and LISREL procedures, highlighting their use in modeling
constructs with ordinal indicators
Ultrafast QND measurements based on diamond-shape artificial atom
We propose a Quantum Non Demolition (QND) read-out scheme for a
superconducting artificial atom coupled to a resonator in a circuit QED
architecture, for which we estimate a very high measurement fidelity without
Purcell effect limitations. The device consists of two transmons coupled by a
large inductance, giving rise to a diamond-shape artificial atom with a logical
qubit and an ancilla qubit interacting through a cross-Kerr like term. The
ancilla is strongly coupled to a transmission line resonator. Depending on the
qubit state, the ancilla is resonantly or dispersively coupled to the
resonator, leading to a large contrast in the transmitted microwave signal
amplitude. This original method can be implemented with state of the art
Josephson parametric amplifier, leading to QND measurements in a few tens of
nanoseconds with fidelity as large as 99.9 %.Comment: 5 pages, 4 figure
Triple seesaw mechanism
On fitting the type II seesaw mechanism into the type I seesaw mechanism, we
obtain a formula to the neutrino masses which get suppressed by high-scale
in its denominator. As a result, light neutrinos are naturally obtained
with new physics at TeV scale. As interesting consequence, the mechanism may be
directly probed at the LHC by directly producing the TeV states intrinsic of
the mechanism. We show that the 3-3-1 model with right-handed neutrinos
realizes naturally such seesaw mechanism.Comment: About 13 pages, no figure
Outflows, Inflows and Young Stars in the inner 200 pc of the Seyfert galaxy NGC 2110
We present a two-dimensional mapping of stellar population age components,
emission-line fluxes, gas excitation and kinematics within the inner
pc of the Seyfert 2 galaxy NGC 2110. We used the Gemini North Integral Field
Spectrograph (NIFS) in the J and K bands at a spatial resolution of
pc. The unresolved nuclear continuum is originated in combined contributions of
young stellar population (SP; age Myr), a featureless AGN continuum
and hot dust emission. The young-intermediate SP (age Myr) is
distributed in a ring-shaped structure at pc from the nucleus,
which is roughly coincident with the lowest values of the stellar velocity
dispersion. In the inner pc the old SP (age Gyr) is dominant.
The [FeII]1.25m emission-line flux distribution is correlated with the
radio emission and its kinematics comprise two components, one from gas
rotating in the galaxy plane and another from gas in outflow within a bicone
oriented along north-south. These outflows seem to originate in the interaction
of the radio jet with the ambient gas producing shocks that are the main
excitation mechanism of the [FeII] emission. We estimate: (1) an ionized gas
mass outflow rate of M/yr at 70 pc from the nucleus;
and (2) a kinetic power for the outflow of only 0.05% of the AGN bolometric
luminosity implying weak feedback effect on the galaxy.Comment: Accepted for publication in MNRA
Sequential Allocation and Balancing Prognostic Factors in a Psychiatric Clinical Trial
In controlled clinical trials, each of several prognostic factors should be balanced across the trial arms. Traditional restricted randomization may be proved inadequate especially with small sample sizes. In psychiatric disorders such as obsessive compulsive disorder (OCD), small trials prevail. Therefore, procedures to minimize the chance of imbalance between treatment arms are advisable. This paper describes a minimization procedure specifically designed for a clinical trial that evaluates treatment efficacy for OCD patients. Aitchison's compositional distance was used to calculate vectors for each possibility of allocation in a covariate adaptive method. Two different procedures were designed to allocate patients in small blocks or sequentially one-by-one. Partial results of this allocation procedure as well as simulated ones are shown. In the clinical trial for which this procedure was developed, the balancing between treatment arms was achieved successfully. Simulations of results considering different arrival order of patients showed that most of the patients are allocated in a different treatment arm if arrival order is modified. Results show that a random factor is maintained with the random arrival order of patients. This specific procedure allows the use of a large number of prognostic factors for the allocation decision and was proved adequate for a psychiatric trial design
Storage and Retrieval of a Microwave Field in a Spin Ensemble
We report the storage and retrieval of a small microwave field from a
superconducting resonator into collective excitations of a spin ensemble. The
spins are nitrogen-vacancy centers in a diamond crystal. The storage time of
the order of 30 ns is limited by inhomogeneous broadening of the spin ensemble.Comment: 4 pages + supplementary material. Submitted to PR
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