971 resultados para Anthony G. Marshall
Resumo:
A complete census of planetary systems around a volume-limited sample of solar-type stars (FGK dwarfs) in the Solar neighborhood (d a parts per thousand currency signaEuro parts per thousand 15 pc) with uniform sensitivity down to Earth-mass planets within their Habitable Zones out to several AUs would be a major milestone in extrasolar planets astrophysics. This fundamental goal can be achieved with a mission concept such as NEAT-the Nearby Earth Astrometric Telescope. NEAT is designed to carry out space-borne extremely-high-precision astrometric measurements at the 0.05 mu as (1 sigma) accuracy level, sufficient to detect dynamical effects due to orbiting planets of mass even lower than Earth's around the nearest stars. Such a survey mission would provide the actual planetary masses and the full orbital geometry for all the components of the detected planetary systems down to the Earth-mass limit. The NEAT performance limits can be achieved by carrying out differential astrometry between the targets and a set of suitable reference stars in the field. The NEAT instrument design consists of an off-axis parabola single-mirror telescope (D = 1 m), a detector with a large field of view located 40 m away from the telescope and made of 8 small movable CCDs located around a fixed central CCD, and an interferometric calibration system monitoring dynamical Young's fringes originating from metrology fibers located at the primary mirror. The mission profile is driven by the fact that the two main modules of the payload, the telescope and the focal plane, must be located 40 m away leading to the choice of a formation flying option as the reference mission, and of a deployable boom option as an alternative choice. The proposed mission architecture relies on the use of two satellites, of about 700 kg each, operating at L2 for 5 years, flying in formation and offering a capability of more than 20,000 reconfigurations. The two satellites will be launched in a stacked configuration using a Soyuz ST launch vehicle. The NEAT primary science program will encompass an astrometric survey of our 200 closest F-, G- and K-type stellar neighbors, with an average of 50 visits each distributed over the nominal mission duration. The main survey operation will use approximately 70% of the mission lifetime. The remaining 30% of NEAT observing time might be allocated, for example, to improve the characterization of the architecture of selected planetary systems around nearby targets of specific interest (low-mass stars, young stars, etc.) discovered by Gaia, ground-based high-precision radial-velocity surveys, and other programs. With its exquisite, surgical astrometric precision, NEAT holds the promise to provide the first thorough census for Earth-mass planets around stars in the immediate vicinity of our Sun.
Resumo:
Background: Acute respiratory distress syndrome (ARDS) is associated with high in-hospital mortality. Alveolar recruitment followed by ventilation at optimal titrated PEEP may reduce ventilator-induced lung injury and improve oxygenation in patients with ARDS, but the effects on mortality and other clinical outcomes remain unknown. This article reports the rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART). Methods/Design: ART is a pragmatic, multicenter, randomized (concealed), controlled trial, which aims to determine if maximum stepwise alveolar recruitment associated with PEEP titration is able to increase 28-day survival in patients with ARDS compared to conventional treatment (ARDSNet strategy). We will enroll adult patients with ARDS of less than 72 h duration. The intervention group will receive an alveolar recruitment maneuver, with stepwise increases of PEEP achieving 45 cmH(2)O and peak pressure of 60 cmH2O, followed by ventilation with optimal PEEP titrated according to the static compliance of the respiratory system. In the control group, mechanical ventilation will follow a conventional protocol (ARDSNet). In both groups, we will use controlled volume mode with low tidal volumes (4 to 6 mL/kg of predicted body weight) and targeting plateau pressure <= 30 cmH2O. The primary outcome is 28-day survival, and the secondary outcomes are: length of ICU stay; length of hospital stay; pneumothorax requiring chest tube during first 7 days; barotrauma during first 7 days; mechanical ventilation-free days from days 1 to 28; ICU, in-hospital, and 6-month survival. ART is an event-guided trial planned to last until 520 events (deaths within 28 days) are observed. These events allow detection of a hazard ratio of 0.75, with 90% power and two-tailed type I error of 5%. All analysis will follow the intention-to-treat principle. Discussion: If the ART strategy with maximum recruitment and PEEP titration improves 28-day survival, this will represent a notable advance to the care of ARDS patients. Conversely, if the ART strategy is similar or inferior to the current evidence-based strategy (ARDSNet), this should also change current practice as many institutions routinely employ recruitment maneuvers and set PEEP levels according to some titration method.
Resumo:
A uniform algebra A on its Shilov boundary X is maximal if A is not C(X) and no uniform algebra is strictly contained between A and C(X) . It is essentially pervasive if A is dense in C(F) whenever F is a proper closed subset of the essential set of A. If A is maximal, then it is essentially pervasive and proper. We explore the gap between these two concepts. We show: (1) If A is pervasive and proper, and has a nonconstant unimodular element, then A contains an infinite descending chain of pervasive subalgebras on X . (2) It is possible to find a compact Hausdorff space X such that there is an isomorphic copy of the lattice of all subsets of N in the family of pervasive subalgebras of C(X). (3) In the other direction, if A is strongly logmodular, proper and pervasive, then it is maximal. (4) This fails if the word “strongly” is removed. We discuss examples involving Dirichlet algebras, A(U) algebras, Douglas algebras, and subalgebras of H∞(D), and develop new results that relate pervasiveness, maximality, and relative maximality to support sets of representing measures.
Resumo:
This report discusses steps for the integration and adoption of information and communication technologies (ICT) in Uganda schools. Barriers of ICT adoption for teachers were determined through surveys at three schools in Eastern Uganda. Teachers identified lack of familiarity of ICT resources and lack of ICT skills as the two greatest barriers to ICT integration. Administrators and staffs were also interviewed to determine current resources. Through observations, interviews and collected data the report addresses two major ideas, promoting utilization of ICT resources and development of sustainable ICT programs. Promotion of utilization not only relies on overcoming the major barriers listed, but also developing a positive attitude of ICT. Sustainability is an issue reliant on all three groups of the school community; administration, staff and users.
Resumo:
The rationale for policy interest in career development services, and the way in which this rationale is being strengthened by the current transformations in work and career, are discussed. The potential roles of public policy in relation to career development services are explored, along with ways in which such services can influence the policy-making process. A range of policy issues related to making career development services available to all throughout life are identified: these include the nature of such services, where they are to be located, and who is to pay for them. It is argued that there is a need for stronger structures and processes to bring together career development practitioners with policy- makers and other stakeholder interests in order to address tasks of common concern, at both national and international levels.
Resumo:
El trabajo analiza la base para el interés político en los servicios de desarrollo vocacional, y la manera en la cual esta base está siendo fortalecida por las actuales transformaciones en el trabajo y en el desarrollo vocacional. Se exploran los papeles potenciales de la política pública en los servicios de desarrollo vocacional así como las formas en las que dichos servicios pueden influenciar el proceso de la creación de políticas. Se identifican una gama de temas de política relacionados con los servicios de desarrollo vocacional disponibles para todos a lo largo de toda la vida: estos incluyen la naturaleza de ese tipo de servicios, dónde deben situarse, y quién debe pagar por ellos. Se sostiene que existe la necesidad de estructuras y procesos más fuertes a fin de reunir a quienes hacen del desarrollo vocacional su profesión habitual y a quienes hacen las políticas y a otros grupos interesados para estudiar tareas de interés común, tanto en el nivel nacional como en el internacional.
Resumo:
The rationales for comparative studies of guidance systems are outlined. The key differences between guidance systems in different countries can be related to stage of economic development, to the political system, to social and cultural factors, to the education and training system, and to professional and organisational structures. The competing pressures towards convergence and divergence between guidance systems are explored.
Resumo:
Se bosquejan las bases lógicas para los estudios comparativos de los sistemas de orientación. Las diferencias fundamentales entre sistemas de orientación en distintos países pueden relacionarse con el estado de desarrollo económico, con el sistema político, con factores sociales y culturales, con la educación y los sistemas de capacitación, y con las estructuras profesionales y organizativas. Se exploran las presiones en conflicto hacia la convergencia y divergencia entre los sistemas de orientación.
Resumo:
The rationale for policy interest in career development services, and the way in which this rationale is being strengthened by the current transformations in work and career, are discussed. The potential roles of public policy in relation to career development services are explored, along with ways in which such services can influence the policy-making process. A range of policy issues related to making career development services available to all throughout life are identified: these include the nature of such services, where they are to be located, and who is to pay for them. It is argued that there is a need for stronger structures and processes to bring together career development practitioners with policy- makers and other stakeholder interests in order to address tasks of common concern, at both national and international levels.
Resumo:
El trabajo analiza la base para el interés político en los servicios de desarrollo vocacional, y la manera en la cual esta base está siendo fortalecida por las actuales transformaciones en el trabajo y en el desarrollo vocacional. Se exploran los papeles potenciales de la política pública en los servicios de desarrollo vocacional así como las formas en las que dichos servicios pueden influenciar el proceso de la creación de políticas. Se identifican una gama de temas de política relacionados con los servicios de desarrollo vocacional disponibles para todos a lo largo de toda la vida: estos incluyen la naturaleza de ese tipo de servicios, dónde deben situarse, y quién debe pagar por ellos. Se sostiene que existe la necesidad de estructuras y procesos más fuertes a fin de reunir a quienes hacen del desarrollo vocacional su profesión habitual y a quienes hacen las políticas y a otros grupos interesados para estudiar tareas de interés común, tanto en el nivel nacional como en el internacional.
Resumo:
The rationales for comparative studies of guidance systems are outlined. The key differences between guidance systems in different countries can be related to stage of economic development, to the political system, to social and cultural factors, to the education and training system, and to professional and organisational structures. The competing pressures towards convergence and divergence between guidance systems are explored.
Resumo:
Se bosquejan las bases lógicas para los estudios comparativos de los sistemas de orientación. Las diferencias fundamentales entre sistemas de orientación en distintos países pueden relacionarse con el estado de desarrollo económico, con el sistema político, con factores sociales y culturales, con la educación y los sistemas de capacitación, y con las estructuras profesionales y organizativas. Se exploran las presiones en conflicto hacia la convergencia y divergencia entre los sistemas de orientación.