895 resultados para Guggenheimer, Elinor C. , 1912-2008
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为了研究12C6+离子辐照昆明小鼠全脑对其空间记忆的影响,采用0、0.5、1和2Gy的12C6+离子束辐照昆明小鼠全脑,用八臂迷宫测试小鼠在迷宫中的觅食速度,以及其空间记忆的变化。结果发现,辐照使小鼠的觅食速度降低,但随着训练次数的增加,受辐照组与对照组的觅食速度都提高,到训练第17天,辐照组与对照组觅食能力基本相同;辐照使小鼠的空间记忆能力短期下降,但随着时间的增加,辐照组小鼠的空间记忆能力恢复到了对照水平。以上结果提示,在0~2Gy的碳离子辐照的剂量水平,辐照在短期内影响小鼠的记忆,在一定时间后,这种影响得到恢复。
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Aims.We aim to provide the atmospheric parameters and rotational velocities for a large sample of O- and early B-type stars, analysed in a homogeneous and consistent manner, for use in constraining theoretical models. Methods: Atmospheric parameters, stellar masses, and rotational velocities have been estimated for approximately 250 early B-type stars in the Large (LMC) and Small (SMC) Magellanic Clouds from high-resolution VLT-FLAMES data using the non-LTE TLUSTY model atmosphere code. This data set has been supplemented with our previous analyses of some 50 O-type stars (Mokiem et al. 2006, 2007) and 100 narrow-lined early B-type stars (Hunter et al. 2006; Trundle et al. 2007) from the same survey, providing a sample of ~400 early-type objects. Results: Comparison of the rotational velocities with evolutionary tracks suggests that the end of core hydrogen burning occurs later than currently predicted and we argue for an extension of the evolutionary tracks. We also show that the large number of the luminous blue supergiants observed in the fields are unlikely to have directly evolved from main-sequence massive O-type stars as neither their low rotational velocities nor their position on the H-R diagram are predicted. We suggest that blue loops or mass-transfer binary systems may populate the blue supergiant regime. By comparing the rotational velocity distributions of the Magellanic Cloud stars to a similar Galactic sample, we find that (at 3s confidence level) massive stars (above 8 M?) in the SMC rotate faster than those in the solar neighbourhood. However there appears to be no significant difference between the rotational velocity distributions in the Galaxy and the LMC. We find that the v sin i distributions in the SMC and LMC can modelled with an intrinsic rotational velocity distribution that is a Gaussian peaking at 175 km s-1 (SMC) and 100 km s-1 (LMC) with a 1/e half width of 150 km s-1. We find that in NGC 346 in the SMC, the 10-25 M? main-sequence stars appear to rotate faster than their higher mass counterparts. It is not expected that O-type stars spin down significantly through angular momentum loss via stellar winds at SMC metallicity, hence this could be a reflection of mass dependent birth spin rates. Recently Yoon et al. (2006) have determined rates of GRBs by modelling rapidly rotating massive star progenitors. Our measured rotational velocity distribution for the 10-25 M? stars is peaked at slightly higher velocities than they assume, supporting the idea that GRBs could come from rapid rotators with initial masses as low as 14 M? at low metallicities.
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A quantitative approach is used to understand the chain growth mechanism in FT synthesis on the Ru, Fe, Rh, and Re surfaces. The C-C coupling reactions are extensively calculated on the stepped metal surfaces. Combining the coupling barriers and reactant stabilities, we investigate the reaction rates of all possible C, + C-1 coupling pathways on the metal surfaces. It is found that (i) all the transition-state structures are similar on these surfaces, while some coupling barriers are very different; (ii) the dominant chain growth pathways on these surfaces are different: C + CH and CH + CH on Rh and Ru surfaces, C + CH3 on Fe surface, and C + CH on Re surface. The common features of the major coupling reactions together with those on the Co surface are also discussed.
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We report our attempts to locate the progenitor of the peculiar Type Ic SN 2007gr in Hubble Space Telescope (HST) preexplosion images of the host galaxy, NGC 1058. Aligning adaptive optics Altair/NIRI imaging of SN 2007gr from the Gemini ( North) Telescope with the preexplosion HST WFPC2 images, we identify the supernova (SN) position on the HST frames with an accuracy of 20 mas. Although nothing is detected at the SN position, we show that it lies on the edge of a bright source 134 +/- 23 mas (6.9 pc) from its nominal center. On the basis of its luminosity, we suggest that this object is possibly an unresolved, compact, and coeval cluster and that the SN progenitor was a cluster member, although we note that model profile fitting favors a single bright star. We find two solutions for the age of this assumed cluster: 7 -/+ 0.5 Myr and 20 - 30 Myr, with turnoff masses of 28 +/- M-circle dot and 12 - 9 M-circle dot, respectively. Preexplosion ground-based K- band images marginally favor the younger cluster 4 age/higher turnoff mass. Assuming the SN progenitor was a cluster member, the turnoff mass provides the best estimate for its initial mass. More detailed observations, after the SN has faded, should determine whether the progenitor was indeed part of a cluster and, if so, allow an age estimate to within similar to 2 Myr, thereby favoring either a high-mass single star or lower-mass interacting binary progenitor.
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Este trabajo se enmarcará en la primera presidencia de George W. Bush y más especficamente entre el 11 de septiembre de 2001 cuando se dio el ataque a las torres gemelas y la invasión a Afganistán el 7 de octubre de este mismo año. En consecuencia lo que se busca con este estudio es demostrar que el gobierno estadounidense se ayuda de herramientas y elementos como la comunicación política, la fijación de agenda y el discurso para la inscripción del concepto terrorismo en la agenda gubernamental. Es así como genera un gran poder de influencia a nivel local logrando que los ciudadanos se tornen hacia el Estado y al mismo tiempo logra apoyo internacional generando el clima perfecto para legitimar la guerra anti-terrorista como una respuesta a los hechos ocurridos.
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En el presente trabajo se realiza una exploración de la posible relación que existe entre la psicosis y el proceso creativo desde una perspectiva psicoanalítica, ilustrando esta relación con el análisis de casos especficos. Con base en una revisión de la literatura sobre los conceptos de psicosis, sublimación y creatividad desde el enfoque psicodinámico, se hace un acercamiento a la teoría de arte Outsider, puntuando algunos aspectos relativos a las obras de determinados artistas en relación con los conceptos revisados.
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Resumen tomado de la publicación
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Mode of access: Internet.
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En este trabajo nos proponemos analizar la colocación latina poena afficere, ‘imponer un castigo’, un tipo de colocación con especificidades tanto sintácticas como semánticas que la distinguen de las construcciones verbo-nominales más prototípicas: el sustantivo predicativo funciona no como Objeto Directo sino como tercer argumento del verbo soporte, un esquema sintáctico que, como intentaremos demostrar, resulta ideal para la expresión de predicados causativos. De los ejemplos documentados de poena afficere en un amplio corpus de textos, intentaremos destacar las principales características de este tipo de colocación. Para su descripción y formalización nos serviremos del marco teórico propuesto por la Teoría Sentido-Texto.
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El interés de este caso de estudio es reflexionar sobre los procesos participativos en la formulación de instrumentos de planeamiento urbano y sus efectos en la gestión de las ciudades, particularmente en el espacio público. Esto se realiza partir de una revisión normativa en el presente y de algunos aspectos históricos de los procesos de “Participación Ciudadana” y del concepto de “Espacio Público” como escenarios propicios para que la ciudadanía aporte en las decisiones de planificación. Además, se plantea una revisión de cmo estos se constituyen en elementos estructurantes de la ciudad que la dotan de identidad, referentes simbólicos y apropiación ciudadana. Para este efecto, se realizó un balance de la estrategia de gestión social y participativa propuesta por el Plan Maestro de Espacio Público de 2005, con el fin de resaltar la importancia de la participación ciudadana en la gestión de los instrumentos de planificación con los que cuenta la ciudad y sus resultados en la gestión de espacio público en Bogotá.
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Classical negotiation models are weak in supporting real-world business negotiations because these models often assume that the preference information of each negotiator is made public. Although parametric learning methods have been proposed for acquiring the preference information of negotiation opponents, these methods suffer from the strong assumptions about the specific utility function and negotiation mechanism employed by the opponents. Consequently, it is difficult to apply these learning methods to the heterogeneous negotiation agents participating in e‑marketplaces. This paper illustrates the design, development, and evaluation of a nonparametric negotiation knowledge discovery method which is underpinned by the well-known Bayesian learning paradigm. According to our empirical testing, the novel knowledge discovery method can speed up the negotiation processes while maintaining negotiation effectiveness. To the best of our knowledge, this is the first nonparametric negotiation knowledge discovery method developed and evaluated in the context of multi-issue bargaining over e‑marketplaces.
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This volume is the second in a series that addresses change and development in the delivery of vocational and education programs in Queensland. A similar volume was published in 2007. Considerable change was foreshadowed for TAFE Queensland by the release of The Queensland Skill Plan (QSP) in 2006. This volume addresses implementation issues for the Actions identified in the QSP. The chapters focus on a breadth of issues that relate to the changing landscape for teaching and learning in TAFE Institutes. The incorporation of Information Communication Technologies (ICTs) and e-learning approaches into the delivery of training packages remain key foci for change, as was evident in the first volume of this series. The chapters also consider issues for some client groups in VET, as well as approaches to professional development to build the capabilities of staff for new teaching and learning environments. The chapter by Sandra Lawrence examines the professional development issues for staff across TAFE institutes in the implementation of the Learning Management System. Suzanne Walsh discusses the issues of new “learning spaces” and “Mode 2 learning in the re-development at Southbank Institute. The chapter by Angela Simpson focuses on VET in schools and school-to-work transition programs. Josie Drew, in her chapter, takes up the issues of embedding employability skills into the delivery of training packages through flexible delivery. The chapter by Colleen Hodgins focuses on the organisational challenges for Lead Institutes in relation to the professional development for TAFE educators in light of policy changes. Bradley Jones discusses the changing roles of libraries in VET contexts and their importance. He examines the adequacy of the VOCED database and reflects on the current nature, role, and practices of VET libraries. Finally, Piero Dametto discusses the pragmatics for TAFE educators in understanding the use of digital objects and learning objects within the LMS and LCMS systems that were presaged in the QSP. These papers were completed by the authors as a part of their postgraduate studies at QUT. The views reported are those of the authors and should not be attributed to the Queensland Department of Education, Training and the Arts. Donna Berthelsen Faculty of Education Queensland University of Technology