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Título, resumen, palabras clave en español e ingles Resumen basado en el de la publicación Se describe cómo estudiantes de enfermería expresan niveles de incomodidad visual al leer texto en papel ultrablanco y en papel de color beige, ya sea con iluminación estándar del aula (600 lux; n = 31) o con iluminación reducida (400 lux ; n = 25). Bajo la iluminación estándar, 10 (28%) de los sujetos informaron niveles notables de estrés visual (puntuación ≥ 15 en una escala de1 a 30). Al leer en color beige, el grupo presentó menos malestar en los síntomas. Estas diferencias fueron estadísticamente significativas para cinco síntomas y el total de malestar. Los resultados fueron menos pronunciados para el grupo en la condición de iluminación reducida. Encontrándose que la incomodidad de lectura relacionada con estrés visual también puede afectar a lectores expertos y, además, que simples ajustes a la iluminación y/o medios visuales pueden reducirla. Se discuten las implicaciones para la práctica en entornos educativos y sanitarios. ESP

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Resumen tomado de la publicación En los últimos años ha aumentado el número artículos recogidos en revistas de Psicología de la Educación que discuten acerca de la incidencia de alumnos con bajo nivel de alfabetización y bajas habilidades aritméticas en las aulas. Por otro lado, en relación al ámbito de la educación, los medios no han tenido dificultades para obtener, de manera informal, datos de empleados y educadores que sugieren un descenso en las competencias académicas, de alfabetización y numéricas. Este trabajo examina la literatura perteneciente a los años 90 y la actualidad, donde se observan problemas relacionados con la alfabetización y las habilidades aritméticas en los países de la OCDE. También se analiza en qué medida los cambios en el contexto del aula pueden haber tenido un impacto negativo en la lectura y dificultades del aprendizaje. En concreto, se analiza el papel que puede estar jugando un déficit específico de percepción visual (síndrome Meares-Irlen / estrés visual) en los procesos de alfabetización y adquisición de habilidades aritméticas, explorando la posibilidad de que la actual tendencia a integrar iluminación fluorescente y medios visuales brillantes en las aulas, hayan contribuido a aumentar las dificultades en la adquisición de estas habilidades. Universidad de Oviedo. Biblioteca de Formación del Profesorado y Educación; Calle Aniceto Sela s/n; 33005 Oviedo; Tel. +34985103215; Fax +34985103214; buoccee@uniovi.es ESP

Mediastinal fat necrosis (MFN) or epipericardial fat necrosis, as it is commonly referred to in the literature, is a rare self-limiting cause of chest pain of unclear etiology. MFN affects previously healthy individuals who present with acute pleuritic chest pain. Characteristic computed tomography (CT) findings include a fat attenuation lesion with intrinsic and surrounding increased attenuation stranding. There is often associated thickening of the adjacent pericardium and/or pleural effusions. We present two cases of MFN manifesting as ovoid fat attenuation lesions demarcated by a soft tissue attenuation rim with intrinsic and surrounding soft tissue attenuation stranding and review the clinical and pathologic features of these lesions. Knowledge of the clinical presentation of patients with MFN and familiarity with the characteristic imaging findings of these lesions should allow radiologists to prospectively establish the correct diagnosis and suggest conservative management and follow-up.

In 1971 the Secondary Schools Board of New South Wales introduced a new English Syllabus for Forms I-IV (later to be termed Years 7—10). This Syllabus embodied the main principles of what is often referred to as the 'new English'. It sought 'a deliberate shift in emphasis from English as information to English as activity'; it saw mastery of the language as being achieved through its lively use in situations which had meaning and purpose for the pupil; it quoted with approval the dictum that 'English is the meeting point of experience, language and society'; it stressed the integration of the various aspects of English.

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An apparatus was constructed to measure the thermal conductivity of powders in vacuum from 150° to 350°K. It was found that the conductivity of selected silicate powders can be adequately represented, within the experimental errors, by a temperature independent term related to the contact conduction plus a temperature cube term which is due to radiative transfer between and through the grains. The conductivity for glass spheres approximately suggests an inverse grain size dependence and does not appear to be related in any simple manner to the elastic contact area between the spheres. The effects of angular grains, produced by crushing, and limited chemical composition range are not significant when compared with the experimental errors. The radiative transfer term which is grossly independent of chemical composition and grain texture is dominated by radiation between the grains for grain sizes > 300 μ. Radiation through the grains is significant for grain sizes < 100 μ. Previous interpretations of the eclipse observations of Pettit and Nicholson indicate that homogeneous constant thermal property models provide an adequate fit. The recent lunation observations of Murray and Wildey cannot be adequately explained by homogeneous models with either constant thermal properties or with thermal properties which are based on the results of this experimental investigation and existing specific heat data. It is suggested that the possibility of layering can best be examined in the region of the morning terminator.

Titanate ceramic waste forms were prepared using several combinations of calcination atmosphere (N{sub 2}, N{sub 2} {minus} 3.5% H{sub 2},h{sub 2}) and metallic redox buffers (Ni,Fe,Ti,Al) to examine the dependence of microstructure and durability upon oxygen activity. It was found that the microstructures and phase assemblages were mostly insensitive to the fabrication method, although in detail systematic changes were recognized. The correlation of aqueous durability with oxygen fugacity was not straightforward because of density variations in the hot-pressed ceramics. These fluctuations in density dominated the dissolution characteristics of the waste forms and sometimes obscured the more subtle changes associated with redox potential. It is concluded that although the best durability is achieved at lower fugacities (i.e., Ti metal buffer and H{sub 2} calcination atmosphere), a satisfactory product can be produced using any of the preparative routes examined, provided the material is completely densified.

The tolerance of titanate nuclear waste ceramics to fluctuations in the concentrations of processing contaminants was monitored using x-ray diffraction, electron microscopy, secondary ion mass spectrometry, and analysis of dissolution liquors. Several waste forms were fabricated, all of which contained idealized Purex waste simulant and, in addition, varying quantities of the common waste stream impurities P{sub 2}O{sub 5}, MgO, Fe{sub 2}O{sub 3}, Na{sub 2}O, and SiO{sub 2}. Incorporation of the oxides individually stabilized new phases including monazite (P{sub 2}O{sub 5}), pseudobrookite (MgO), loveringite (Fe{sub 2}O{sub 3}), freudenbergite (Na{sub 2}O), and pollucite (SiO{sub 2})--only the latter phase deleteriously affected waste form performance by promoting cesium dissolution. However, when the processing contaminants were added simultaneously, a number of synergetic effects, particularly the stabilization of a soluble glassy phase, resulted in elemental losses which were an order of magnitude greater for some matrix and radwaste species. It was found that up to 25 wt% of the idealized Purex waste could be incorporated in the waste without diminution of its properties.

A titanate ceramic designed to immobilize high-level waste generated by Amine reprocessing of heavy-water reactor fuel and fabricated by uniaxial hot-pressing was characterized. X-ray diffraction and selected-area electron diffraction were used to identify a six-phase assemblage consisting of betafite, a hollandite structure type, perovskite, uraninite, hibonite, and Magneli phases. Secondary electron imaging of polished surfaces revealed many microvoids consistent with a measured density of 5.25 g · cm−2 (∼90% of theoretical density). The waste form was chemically heterogeneous at the hundreds of micrometers scale, as backscattered electron imaging and energy-dispersive X-ray spectroscopy indicated that regions rich in either uranium or titanium oxides were common. Grain sizes ranged from 0.1 to 0.5 μm. All crystals were faceted with the exception of anhedral uraninite grains. Dissolution experiments conducted at 90°C in distilled water gave uranium and titanium loss rates which were solubility limited (10−1 to 10−4 g · m−2· d−1), while cesium dissolution, which was not contrained by solubility limits, was more rapid (23.3 g · m−2· d−1). Hydrothermal testing at 150°C in distilled water resulted in precipitation of uranium(VI) titanate (UTiO5) and brookite (TiO2).

The phase chemistries and microstructures of titanate-based ceramics containing simulated high-level nuclear waste with varying sodium contents were compared. Incorporation of relatively low sodium levels resulted in more complex phase assemblages. The principal hosts for sodium were hibonite and freudenbergite, and, when iron and sodium were present in combination, loveringite was also stabilized. During fabrication, oxygen potential was controlled by Ti-TiO/sub 2/ or TiH/sub 2/-Ti/sub 3/O/sub 5/ solid-state buffers. These metal and hydride oxygen getters behaved similarly, neither disturbing the phase assemblages nor significantly altering the partitioning of waste elements between radiophases. It is believed that the hydrothermal stability of the sodium-bearings ceramics (containing up to 2.7 wt% Na/sub 2/O) will be comparable to sodium-free material, since less durable sodium-rich phases are encapsulated in a resistant matrix. Extensive formation of glassy phases may cause embrittlement at higher sodium loadings.