7,449 research outputs found
Constraints to the magnetospheric properties of T Tauri stars - II. The Mg II ultraviolet feature
The atmospheric structure of T Tauri Stars (TTSs) and its connection with the
large scale outflow is poorly known. Neither the effect of the magnetically
mediated inter- action between the star and the disc in the stellar atmosphere
is well understood. The Mg II multiplet is a fundamental tracer of TTSs
atmospheres and outflows, and is the strongest feature in the near-ultraviolet
spectrum of TTSs. The International Ultraviolet Explorer and Hubble Space
Telescope data archives provide a unique set to study the main physical
compounds contributing to the line profile and to derive the properties of the
line formation region. The Mg II profiles of 44 TTSs with resolution 13,000 to
30,000 are available in these archives. In this work, we use this data set to
measure the main observables: flux, broadening, asymmetry, terminal velocity of
the outflow, and the velocity of the Discrete Absorption Components. For some
few sources repeated observations are available and variability has been
studied. There is a warm wind that at sub-AU scales absorbs the blue wing of
the Mg II profiles. The main result found in this work is the correlation
between the line broadening, Mg II flux, terminal velocity of the flow and
accretion rate. Both outflow and magnetospheric plasma contribute to the Mg II
flux. The flux-flux correlation between Mg II and C IV or He II is confirmed;
however, no correlation is found between the Mg II flux and the ultraviolet
continuum or the H2 emission.Comment: 21 pages, 20 figure
Constraints to the magnetospheric properties of T Tauri stars. I. The C II], Fe II] and Si II] ultraviolet features
The C II] feature at ~2325 Angstrom is very prominent in the spectra of T
Tauri stars (TTSs). This feature is a quintuplet of semiforbidden transitions
excited at electron temperatures around 10,000 K that, together with the nearby
Si II] and Fe II] features, provides a reliable optically thin tracer for
accurate measurement of the plasma properties in the magnetospheres of TTSs.
The spectra of 20 (out of 27) TTSs observed with the Space Telescope Imaging
Spectrograph (STIS) on board the Hubble Space Telescope (HST) have good enough
signal to noise ratio (S/N) at the C II] wavelength. For these stars we have
determined electron densities (ne) and temperatures (Te) in the line emission
region as well as the profile broadening (sigma). For most of the stars in the
sample (17) we obtain 10^{4.1} < Te < 10^{4.5} K and 10^{8} < ne < 10^{12}
cm^{-3}. These stars have suprathermal line broadening (35 < sigma < 165 km
s^{-1}), except TW Hya and CY Tau with thermal line broadening. Both C II] line
luminosity and broadening are found to correlate with the accretion rate. Line
emission seems to be produced in the magnetospheric accretion flow, close to
the disk. There are three exceptions: DG Tau, RY Tau and FU Ori. The line
centroids are blueshifted indicating that the line emission in these three
stars is dominated by the outflow.Comment: 13 pages, 15 figures, published in MNRAS minor change
PUBLIC INVESTMENT, ECONOMIC PERFORMANCE AND BUDGETARY CONSOLIDATION: VAR EVIDENCE FOR THE FIRST 12 EURO COUNTRIES
In a period of heightened concern about fiscal consolidation in the euro area, a politically expedient way of controlling the public budget is to cut public investment. A critical question, however, is whether or not political expediency comes at a cost, in terms of both long-term economic performance and future budgetary contention efforts. First, common wisdom suggests that public investments have positive effects on economic performance although the empirical evidence is less clear. Second, it is conceivable that public investment has such strong effects on output that over time it generates enough additional tax revenues to pay for itself. Obviously, it is equally plausible that the effects on output although positive are not strong enough for the public investment to pay for itself. In this paper, we investigate these issues empirically for the first twelve countries in the euro area using a vector auto-regressive approach. We conclude that the euro countries can be gathered in four groups according to the nature of the economic and budgetary impact of public investment. The first group includes Austria, Belgium, Luxembourg, and Netherlands, where the economic effects are either negative or positive but very small and, therefore, cuts will be harmless for the economy and effective from a budgetary perspective. The second group includes Finland, Portugal, and Spain, where public investment does not pay for itself and, therefore, cuts are an effective tool of budgetary consolidation although they are harmful for the economy. The third group includes France, Greece, and Ireland where public investment just pays for itself and therefore cuts are not an effective way of achieving long-term budgetary consolidation and are harmful for the economy. Finally, the fourth group includes Germany and Italy, where public investment more than pays for itself and, therefore, cuts are not only harmful for the economy but also counterproductive from a budgetary perspective.Public Investment, Economic Performance, Budgetary Consolidation, Euro Area
Impact of Public Investment Upon Economic Performance and Budgetary Consolidation Efforts in the European Union
In an period of heightened concern about fiscal consolidation in the Euro zone, a politically expedient way of dealing with the situation is to cut public investment. A critical question, however, is whether or not political expediency comes at a cost, in terms of both long-term economic performance and future budgetary consolidation efforts. In fact, one would expect any type of investment, including public investment, to improve the long-term economic performance. Moreover, to the extent that public investment increases output in the long-term, it also expands the tax base and, therefore, tax revenues in the long term. It is conceivable that public investment has such strong effects on output, that over time it generates enough additional tax revenues to pay for itself. It is equally plausible that the effects on output although positive are not strong enough for the public investment to pay for itself. In the first case, cuts in public investment hurt long-term growth and make the future budgetary situation worse. In the second case, cuts in public investment hurt the long-term economic performance without hurting the future budgetary situation. In this paper we investigate this question empirically in the context of a number of countries in the Euro zone using a vector auto-regressive/error correction mechanism approach to determine the effects of aggregated public investment on output, employment and private investment. Our ultimate objective is to determine in which regime do the different countries seem to fit and determine to what extent cuts in public investment may turn out to be counter-productive in the long-term from a budgetary perspective. JEL Classification: C32, E62, H54, O52
Simulação baseada na web: uma ferramenta para o ensino de enfermagem em terapia intensiva
The objectives of this study were to develop, to implement and to evaluate a web-based simulation for critical care nursing, as a tool for teaching nursing students at the undergraduate level. An adapted methodology was used to develop teaching material in a web-based learning environment, consisting of three evaluation phases (ergonomic, pedagogical and usability), carried out by web-designers/programmers, nursing teachers/nurses, and undergraduate nursing students. The research tools used were three different evaluation forms, based on a five-point Likert scale, which were applied after using the simulation. The results garnered from the forms show positive analyses in every evaluation, with special emphasis on the encouragement of learning in the pedagogical evaluation period. In the usability evaluation, the highlight was on the students' satisfaction in using the environment and how easy it was to navigate. This shows the feasibility of using this simulation to improve the learning process.Este estudio tuvo por objetivos desarrollar, implementar y evaluar una simulación de terapia intensiva, utilizando la tecnología web, para la enseñanza de graduación en enfermería. Fue utilizada una metodología adaptada para la construcción de material de instrucción en ambiente de enseñanza web, compuesta por tres fases de evaluación (ergonómica, pedagógica y utilización), realizadas por webdesigners/programadores, docentes/enfermeros y alumnos del curso de graduación en enfermería. Como instrumentos de investigación, fueron aplicados tres diferentes formularios de evaluación, basados en la escala Likert de cinco puntos, después de la utilización de la simulación. Los resultados presentados en los formularios muestran análisis positivos en todas las evaluaciones, destacando en la evaluación pedagógica el estímulo al aprendizaje y en la evaluación de utilización la satisfacción de los alumnos al usar el ambiente y al constatar la facilidad del manoseo, traduciendo la indicación del uso de esa simulación en un proceso para mejorar la enseñanza y el aprendizaje.Este estudo teve por objetivos desenvolver, implementar e avaliar uma simulação em terapia intensiva, utilizando a tecnologia web, para o ensino de graduação em enfermagem. Foi utilizada metodologia adaptada para construção de material instrucional em ambiente de ensino web, composta por três fases de avaliação (ergonômica, pedagógica e usabilidade), realizadas por webdesigners/programadores, docentes/enfermeiros e alunos do curso de graduação em enfermagem. Como instrumentos de pesquisa, foram aplicados três diferentes formulários de avaliação, baseados em escala Likert de cinco pontos, após a utilização da simulação. Os resultados apresentados nos formulários mostram análises positivas em todas as avaliações, destacando na avaliação pedagógica o estímulo ao aprendizado e na avaliação de usabilidade a satisfação dos alunos na utilização do ambiente e a facilidade de manuseio, traduzindo a indicação do uso dessa simulação para melhoria do processo ensino-aprendizagem.Universidade Federal de Santa CatarinaUniversidade Federal de São Paulo (UNIFESP)UNIFESPSciEL
Web-based simulation: a tool for teaching critical care nursing
Este estudo teve por objetivos desenvolver, implementar e avaliar uma simulação em terapia intensiva, utilizando a tecnologia web, para o ensino de graduação em enfermagem. Foi utilizada metodologia adaptada para construção de material instrucional em ambiente de ensino web, composta por três fases de avaliação (ergonômica, pedagógica e usabilidade), realizadas por webdesigners/programadores, docentes/enfermeiros e alunos do curso de graduação em enfermagem. Como instrumentos de pesquisa, foram aplicados três diferentes formulários de avaliação, baseados em escala Likert de cinco pontos, após a utilização da simulação. Os resultados apresentados nos formulários mostram análises positivas em todas as avaliações, destacando na avaliação pedagógica o estímulo ao aprendizado e na avaliação de usabilidade a satisfação dos alunos na utilização do ambiente e a facilidade de manuseio, traduzindo a indicação do uso dessa simulação para melhoria do processo ensino-aprendizagem.Este estudio tuvo por objetivos desarrollar, implementar y evaluar una simulación de terapia intensiva, utilizando la tecnología web, para la enseñanza de graduación en enfermería. Fue utilizada una metodología adaptada para la construcción de material de instrucción en ambiente de enseñanza web, compuesta por tres fases de evaluación (ergonómica, pedagógica y utilización), realizadas por webdesigners/programadores, docentes/enfermeros y alumnos del curso de graduación en enfermería. Como instrumentos de investigación, fueron aplicados tres diferentes formularios de evaluación, basados en la escala Likert de cinco puntos, después de la utilización de la simulación. Los resultados presentados en los formularios muestran análisis positivos en todas las evaluaciones, destacando en la evaluación pedagógica el estímulo al aprendizaje y en la evaluación de utilización la satisfacción de los alumnos al usar el ambiente y al constatar la facilidad del manoseo, traduciendo la indicación del uso de esa simulación en un proceso para mejorar la enseñanza y el aprendizaje.The objectives of this study were to develop, to implement and to evaluate a web-based simulation for critical care nursing, as a tool for teaching nursing students at the undergraduate level. An adapted methodology was used to develop teaching material in a web-based learning environment, consisting of three evaluation phases (ergonomic, pedagogical and usability), carried out by web-designers/programmers, nursing teachers/nurses, and undergraduate nursing students. The research tools used were three different evaluation forms, based on a five-point Likert scale, which were applied after using the simulation. The results garnered from the forms show positive analyses in every evaluation, with special emphasis on the encouragement of learning in the pedagogical evaluation period. In the usability evaluation, the highlight was on the students' satisfaction in using the environment and how easy it was to navigate. This shows the feasibility of using this simulation to improve the learning process
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