2,364 research outputs found
Language Classroom Anxiety: College Students’ Perceptions, Experiences, and Manifestations in a University
The study assessed the factors that contributed to the language anxiety of college female students in the use of English as a second language; their perceptions, experiences, manifestations, and the extent to which the classroom environment contributes to the students’ anxiety in learning the target language. The mixed method was used in the study with quantitative and qualitative data analysis. The quantitative dealt with numeric data and analyses, while qualitative dealt with narrative data and analyses. The Foreign Language Classroom Anxiety Scale [1] was the main research tool used in gathering the data and the Focus Group Discussion (FGD) for an in-depth analysis of the students’ language anxiety. Considering the low-risk status of the study, the Research Ethics Committee approved the research protocol and informed consent in an expedited manner considering the respondents as a non-vulnerable group. In quantitative analysis, the findings revealed that the majority of the respondents agreed having perceived, experienced, and manifested their English language anxiety in the classroom as per composite mean of 3.52; 3.19; and 3.30 respectively. In qualitative analysis, the findings disclosed that three-fourths or a little less of the student respondents had anxiety in each of the ten themes: (1) students’ perceptions in English; (2) actual language anxiety experiences; (3) students’ academic outputs in English; (4) characteristics of English teachers; (5) teaching strategies employed; (6) attendance in English language class; (7) participation in dialogue/role play; (8) importance of English language; (9) fear of negative evaluation; and (10) test-taking. However, some of the anxieties were mitigated by using appropriate teaching strategies and the accommodating-positive attitudes of the English teachers in handling the English class. Hence, regardless of sex and race, the cited related literature and the present findings have revealed that learners of a second/foreign language had experienced anxiety in the classroom. Further studies may be explored to unravel new insights using the time-honored Anxiety Theory not just to test the theory but to build a new one if possible
On Unitary Time Evolution in Gowdy Cosmologies
A non-perturbative canonical quantization of Gowdy polarized models
carried out recently is considered. This approach profits from the equivalence
between the symmetry reduced model and 2+1 gravity coupled to a massless real
scalar field. The system is partially gauge fixed and a choice of internal time
is performed, for which the true degrees of freedom of the model reduce to a
massless free scalar field propagating on a 2-dimensional expanding torus. It
is shown that the symplectic transformation that determines the classical
dynamics cannot be unitarily implemented on the corresponding Hilbert space of
quantum states. The implications of this result for both quantization of fields
on curved manifolds and physically relevant questions regarding the initial
singularity are discussed.Comment: 16 pages, no figures, latex file; references added, a proof included.
Final version to appear in IJMP
PAHs and metals in a coastal lagoon (Esmoriz/Paramos), Portugal
Esmoriz/Paramos is a coastal lagoon on the northwest coast of Portugal with an area of approximately 5.6 km2
and occasional communication with the sea. This habitat has a great ecological importance due to the
characteristics of its fauna and vegetation. For the last 25 years, the wet area of the lagoon has been reduced as
well as its biodiversity and at present it is very degraded and in-filled. The transport of particles from land
through the main affluent is one of the causes for siltation. Pollution sources include untreated sewage water,
industrial effluents and run-off from agricultural activities. Dredging the sediments is the strategy planned by the
local authorities to restore this ecosystem and improve its recreational value. Thus, evaluation of sediment
quality is important for planning disposal purposes. The objective of this work was to evaluate de water quality
of the lagoon and to assess the contamination of its sediments by polycyclic aromatic hydrocarbons (PAHs) and
heavy metals. The water analysis carried out in three different stations within the lagoon, showed a poor quality,
namely low oxygen concentrations and high inorganic nitrogen and biochemical oxygen demand, whereas the
sediments revealed moderate concentrations of PAHs with different patterns of distribution along stations and
depth. Zinc was the most abundant metal followed by copper and smaller concentrations of lead and chromium.
Metal variation in sediments was larger between stations than along depth. Therefore an average concentration
of metals exposure to living organisms was calculated
A Expressão Global da Doença de Chagas – Oportunidades Emergentes e Impacto em Portugal
Chagas disease, caused by the protozoan Trypanosoma cruzi is endemic in the countries of Central and South America. Despite vector control programs and other measures taken in the blood banks and maternity hospitals, it is estimated that there are about eight million people infected worldwide. Although traditionally associated with rural life and poverty, the current migration flows transform it into a global public health problem. In Portugal, this problem is poorly known, with an estimated underdiagnosis index that exceeds 99%. In European countries, besides imported cases, autochthonous infections arise through vertical transmission and blood/organ donation.The conventional serological tests for diagnosing Chagas disease and verifying its cure are indirect hemagglutination (IHA), indirect immunofluorescence (IFAT), and enzyme-linked immunoabsorbent assay (ELISA).The hypothesis of autoimmunity as a basic mechanism of this disease and the absence of early markers of cure are the causes of controversy regarding the specific treatment of this disease. The currently available drugs have adverse effects on a large number of patients and parasitological efficacy in chronic disease is suboptimal.The authors reinforce the need of a high level of suspicion in patients with suggestive epidemiology and the need of populational screening of specific high risk groups
Quantum Gowdy Model: Schrodinger Representation with Unitary Dynamics
The linearly polarized Gowdy model is paradigmatic for studying
technical and conceptual issues in the quest for a quantum theory of gravity
since, after a suitable and almost complete gauge fixing, it becomes an exactly
soluble midisuperspace model. Recently, a new quantization of the model,
possessing desired features such as a unitary implementation of the gauge group
and of the time evolution, has been put forward and proven to be essentially
unique. An appropriate setting for making contact with other approaches to
canonical quantum gravity is provided by the Schr\"odinger representation,
where states are functionals on the configuration space of the theory. Here we
construct this functional description, analyze the time evolution in this
context and show that it is also unitary when restricted to physical states,
i.e. states which are solutions to the remaining constraint of the theory.Comment: 21 pages, version accepted for publication in Physical Review
Uniqueness of the Fock quantization of fields with unitary dynamics in nonstationary spacetimes
The Fock quantization of fields propagating in cosmological spacetimes is not
uniquely determined because of several reasons. Apart from the ambiguity in the
choice of the quantum representation of the canonical commutation relations,
there also exists certain freedom in the choice of field: one can scale it
arbitrarily absorbing background functions, which are spatially homogeneous but
depend on time. Each nontrivial scaling turns out into a different dynamics
and, in general, into an inequivalent quantum field theory. In this work we
analyze this freedom at the quantum level for a scalar field in a
nonstationary, homogeneous spacetime whose spatial sections have
topology. A scaling of the configuration variable is introduced as part of a
linear, time dependent canonical transformation in phase space. In this
context, we prove in full detail a uniqueness result about the Fock
quantization requiring that the dynamics be unitary and the spatial symmetries
of the field equations have a natural unitary implementation. The main
conclusion is that, with those requirements, only one particular canonical
transformation is allowed, and thus only one choice of field-momentum pair (up
to irrelevant constant scalings). This complements another previous uniqueness
result for scalar fields with a time varying mass on , which selects a
specific equivalence class of Fock representations of the canonical commutation
relations under the conditions of a unitary evolution and the invariance of the
vacuum under the background symmetries. In total, the combination of these two
different statements of uniqueness picks up a unique Fock quantization for the
system. We also extend our proof of uniqueness to other compact topologies and
spacetime dimensions.Comment: 12 page
Microtesting of micro-injection molded parts
With the growth and demand for microinjection
moulded thermoplastic parts becoming ever so popular, an increased need for determination and understanding of material mechanical properties at the micro-scale level is observed. One of the most widespread mechanical characterization experiments is the tensile test. The use of miniaturised tensile apparatus is therefore a need. In this work we developed a novel universal microtesting apparatus for performing mechanical tests in micro-mouldigs. The influence of injection moulding processing conditions on the
mechanical behaviour of Polypropylene (PP) and Methyl Methacrylate-Butadiene-Styrene (MABS) microinjection moulded specimens is studied
Algumas espécies coprófilas de Psilocybe (Strophariaceae) do Estado de Pernambuco, Brasil
Coprophilous species Psilocybe argentina, P. pegleriana and P. cubensis are reported for the first time for Northeast Brazil. The last one is a hallucinogenic mushroom. Descriptions, discussions and drawings of the species are provided.As espécies coprófilas Psilocybe argentina, P. pegleriana e P. cubensis são referidas pela primeira vez para o Nordeste Brasileiro, sendo esta última uma espécie de cogumelo alucinógeno. Descrições, discussões e desenhos das espécies são fornecidos
Decoherence times of universal two-qubit gates in the presence of broad-band noise
The controlled generation of entangled states of two quantum bits is a
fundamental step toward the implementation of a quantum information processor.
In nano-devices this operation is counteracted by the solid-state environment,
characterized by a broadband and non-monotonic power spectrum, often 1/f at low
frequencies. For single-qubit gates, incoherent processes due to fluctuations
acting on different time scales result in peculiar short- and long-time
behavior. Markovian noise gives rise to exponential decay with relaxation and
decoherence times, T1 and T2, simply related to the symmetry of the
qubit-environment coupling Hamiltonian. Noise with the 1/f power spectrum at
low frequencies is instead responsible for defocusing processes and algebraic
short-time behavior. In this paper, we identify the relevant decoherence times
of an entangling operation due to the different decoherence channels
originating from solid-state noise. Entanglement is quantified by concurrence,
which we evaluate in an analytic form employing a multi-stage approach. The
'optimal' operating conditions of reduced sensitivity to noise sources are
identified. We apply this analysis to a superconducting \sqrt{i-SWAP} gate for
experimental noise spectra.Comment: 35 pages, 11 figure
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