This report presents an assessment of the efficiency and power density limitations of thermophotovoltaic (TPV) energy conversion systems for both ideal (radiative-limited) and practical (defect-limited) systems. Thermodynamics is integrated into the unique process physics of TPV conversion, and used to define the intrinsic tradeoff between power density and efficiency. The results of the analysis reveal that the selection of diode bandgap sets a limit on achievable efficiency well below the traditional Carnot level. In addition it is shown that filter performance dominates diode performance in any practical TPV system and determines the optimum bandgap for a given radiator temperature. It is demonstrated that for a given radiator temperature, lower bandgap diodes enable both higher efficiency and power density when spectral control limitations are included. The goal of this work is to provide a better understanding of the basic system limitations that will enable successfiil long-term development of TPV energy conversion technology.

Transient radio frequency photoreflectance measurements were performed on 0.53 eV p-type InGaAsSb double heterostructures, grown by organometallic vapor phase epitaxy on lattice matched GaSb substrates, for determining excess carrier lifetime. Direct evidence of photon recycling was observed by changing the GaSb backsurface reflectivity and observing the change in excess carrier lifetime. Consistent with theory developed for this type of structure, effective lifetimes increased by 30%-40% when the backsurface was changed from an absorbing to a reflecting surface. The theory develops a closed-form expression for the total radiative recombination rate, starting with continuity equations for both excess minority carriers and the photon density. Lifetime measurements in these p-InGaAsSb structures with different doping concentrations and epitaxial layer thicknesses allow the extraction of minority carrier recombination parameters. Measurements indicate a value for the radiative recombination coefficient of Bϭ5 -6ϫ10 Ϫ11 cm 3 /s, for the Auger recombination coefficient of Cϭ2 -5ϫ10 Ϫ29 cm 6 /s, for the Shockley-Read-Hall lifetime of 100-150 ns and for the surface recombination velocity of 1 -2ϫ10 3 cm/s.

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SUMMARY This study examined the use of and need for written educational material by the parents of 41 children with cerebral palsy, aged between five and 63 months. After their initial counselling, the majority felt that they needed written information. The parents of 31 children attempted to find suitable books or pamphlets, but in 13 cases they failed to do so or found the material unsatisfactory. A significant association was found between reading material which the parents found satisfactory and their knowledge about the basic features of cerebral palsy. RÉSUMÉ Publications de santë pour les parents d'IMC L'article étudie l'usage et le besoin d'un matériel d'éducation écrit pour les parents de 41 IMC âgés de cinq à 63 mois. Après les conseils initiaux, la majorité des parents ressentent le besoin d'une information écrite. Les parents de 31 enfants avaient essayé de se procurer livres ou articles adaptés mais dans 13 cas, ils n'y étaient pas parvenus ou n'avaient pas trouvé ces écrits satisfaisants. Un lien significatif a été trouvé entre les oeuvres leus jugées satisfaisantes par les parents et leur connaissance des données de base de I'infirmité motrice cérébrale. ZUSAMMENFASSUNG Unterweisungsmaterial für Eltern von Kindern mil Cerebralparese Bei den Eltern von 41 Kindern mit Cerebralparese im Alter zwischen fünf und 63 Monaten wurden der Gebrauch und der Bedarf von schriftlichem Unterweisungsmaterial untersucht. Nach ihrer anfänglichen Unterweisung wollten die meisten schriftliche Informationen haben. Die Eltern von 31 Kindern versuchten brauchbare Bücher oder Zeitschriften zu finden, aber 13 waren nicht erfolgreich oder fanden das Material unbefiedigend. Es fand sich eine signifikante Beziehung zwischen dem Lesen von Material, das die Eltern zufriedenstellend fanden, und ihrer Kenntnis über die Grundlagen der Cerebralparese. RESUMEN Literatura sanitaria para padres con niños con parálisis cerebral Este estudio examina el uso y la necesidad de material educativo escrico dirigido a padres de 41 niños con parálisis cerebral de cinco a 63 meses de edad. Después de unos consejos previos, la mayoria opinó que necesitaba información escrita‐Los padres de 31 niños intentaron hallar libros o panfletos adecuados, pero en 13 casos fracasaron o hallaron un material no satisfactorio. Se halló una asociacion significativa entre la lectura de material que los padres encontraron satisfactoria y sus conocimientos de las caracteristicas básicas de la parálisis cerebral.

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