Ring-theoretic properties of PVMDs

We extend to Pr\"ufer $v$-multiplication domains some distinguished ring-theoretic properties of Pr\"ufer domains. In particular we consider the t##-property, the $t$-radical trace property, $w$-divisoriality and $w$-stability.Comment: 15 pages, to appear in Communications in Algebr

w-Divisorial Domains

We study the class of domains in which each w-ideal is divisorial, extending several properties of divisorial and totally divisorial domains to a much wider class of domains. In particular we consider PvMDs and Mori domains

Semistar Dedekind Domains

Let $D$ be an integral domain and $\star$ a semistar operation on $D$. As a generalization of the notion of Noetherian domains to the semistar setting, we say that $D$ is a $\star$--Noetherian domain if it has the ascending chain condition on the set of its quasi--$\star$--ideals. On the other hand, as an extension the notion of Pr\"ufer domain (and of Pr\"{u}fer $v$--multiplication domain), we say that $D$ is a Pr\"ufer $\star$--multiplication domain (P$\star$MD, for short) if $D_M$ is a valuation domain, for each quasi--$\star_{_{f}}$--maximal ideal $M$ of $D$. Finally, recalling that a Dedekind domain is a Noetherian Pr\"{u}fer domain, we define a $\star$--Dedekind domain to be an integral domain which is $\star$--Noetherian and a P$\star$MD. In the present paper, after a preliminary study of $\star$--Noetherian domains, we investigate the $\star$--Dedekind domains. We extend to the $\star$--Dedekind domains the main classical results and several characterizations proven for Dedekind domains. In particular, we obtain a characterization of a $\star$--Dedekind domain by a property of decomposition of any semistar ideal into a ``semistar product'' of prime ideals. Moreover, we show that an integral domain $D$ is a $\star$--Dedekind domain if and only if the Nagata semistar domain Na$(D, \star)$ is a Dedekind domain. Several applications of the general results are given for special cases of the semistar operation $\star$

Petrology and Geochemistry of Ourika Gneissic Rocks (High-Atlas, Morocco): Implications for Provenance and Geotectonic Setting

Gneissic terranes under studied are one of the various formations constituting the Ourika Old massif. They underwent a metamorphic evolution characterized by a first amphibole facies event and a second greenschist facies metamorphism. The high-grade metamorphism is related to a Pan-African orogenesis that produced subduction-related granitoids preserved as GAA and GBA gneisses. These two gneissic groups have different geochemical compositions which were likely linked to the protolith nature. Petrology and geochemical investigations reveal that the protolith of GBA gneisses is calc-alkali peraluminous S-type granodiorite and thus of GAA gneisses is calc-alkali metaluminous diorite. The GBA protolith showed a continental active margin characteristic that may belong to the earlier Pan-African event, at ~780 to 750 Ma, whereas the GAA protolith could be formed in the island arc/fore-arc event, at ~753 Ma. Both groups were ordered in two lines suggesting two different sources where the crustal intervention is more or less marked, by juvenile upper continental crust for GBA protolith, and by young lower continental crust for GAA protolith. Correlated to the anti-atlasic formations of the same age, the geochemical similarities suggest a comparable geodynamic evolution that is closely linked to a Neoproterozoic continental convergent margin in the north of West-African Craton (WAC), collided at late Pan-African orogenesis. This collision induced the strongly N-S deformation that was materialized by the overthrusting of the GAA protolith onto the GBA protolith, and by the forming of the Ourika gneissic massif as a submeridian dome. Keywords: Ourika old massif; gneissic protoliths; Pan-African orogenesis; mineralogy and geochemistry; geodynamic evolution

Unique representation domains, II

Given a star operation * of finite type, we call a domain R a *-unique representation domain (*-URD) if each *-invertible *-ideal of R can be uniquely expressed as a *-product of pairwise *-comaximal ideals with prime radical. When * is the t-operation we call the *-URD simply a URD. Any unique factorization domain is a URD. Generalizing and unifying results due to Zafrullah and Brewer-Heinzer, we give conditions for a *-ideal to be a unique *-product of pairwise *-comaximal ideals with prime radical and characterize *-URDs. We show that the class of URDs includes rings of Krull type, the generalized Krull domains introduced by El Baghdadi and weakly Matlis domains whose t-spectrum is treed. We also study when the property of being a URD extends to some classes of overrings, such as polynomial extensions, rings of fractions and rings obtained by the D+XD_S[X] construction.Comment: 21 page

Evaluation de l'activité catalytique des composés zirconyle phosphates, alumines bêta et perovskites pour le couplage oxydatif du méthane

Mécanismes réactionnels de l'oxydation partielle du méthane -- Rôle de l'oxygène -- Effet de la température -- Effet de la dilution par un gaz inerte -- Effet du rapport CH4/O2 -- Nature du catalyseur -- Les catalyseurs perovskites -- Catalyseurs à base de métaux nobles -- Modes d'alimentation -- L'oxyde nitreux comme oxydant -- Propriétés physico-chimiques des composés types zirconyles phosphates, de type alumine bêta et perovskites -- Méthodologie -- Dispositif expérimental -- Calcul des conversions et des sélectivités -- Préparation des catalyseurs -- Calcul thermodynamique -- Résultats expérimentaux -- Réacteur vide -- Réacteur avec diluant -- Catalyseurs de type zirconyle phosphate (ZP) -- Catalyseurs types oxydes -- Catalyseurs type perovskites -- Effet de l'ion métallique sur l'activité des catalyseurs type ZP -- Effet de la substitution du zirconium par l'yttrium dans le cas du catalyseur SZP -- Effet du dopage par les métaux de transition dans le composé CZP -- Effet de la structure à base d'oxydes de métaux -- Effet de dopage par les métaux de transition dans les catalyseurs à base de métaux

Algoritmos numéricos de reconstrucción de conductancias

La idea de este trabajo surge de la investigación que están llevando a cabo mis tutores del departamento de matemáticas de la EEBE. Es una investigación que estudia los problemas inversos ydeduce algoritmos para la recuperación de las características interiores de un elemento a partirde aplicarle una entrada y obtener la respuesta . Este trabajo trata de implementar algunos de éstos algoritmos en Matlab y demostrar su vera-cidad además de visualizar el potencial que pueden llegar a tener, ya que se pueden aplicar enmúltiples ámbitos. Este proyecto se puede ampliar en múltiples áreas ya que es el principiode una potente herramienta para el uso industrial, médico, astronómico,... En esta memoria serecoge los fundamentos teóricos del trabajo como los algoritmos implementados. Estos algo-ritmos proceden de los artículos citados en las referencias. Para finalizar, se ofrecen una seriede conclusiones sobre el desarrollo de este trabajo y el cumplimiento de los objetivos marcados

Considering the economic value of natural design elements at city scale

With increasing signs of climate change and the influence of national and international carbon-related laws and agreements, governments all over the world are grappling with how to rapidly transition to low-carbon living. This includes adapting to the impacts of climate change that are very likely to be experienced due to current emission levels (including extreme weather and sea level changes), and mitigating against further growth in greenhouse gas emissions that are likely to result in further impacts. Internationally, the concept of ‘Biophilic Urbanism’, a term coined by Professors Tim Beatley and Peter Newman to refer to the use of natural elements as design features in urban landscapes, is emerging as a key component in addressing such climate change challenges in rapidly growing urban contexts. However, the economics of incorporating such options is not well understood and requires further attention to underpin a mainstreaming of biophilic urbanism. Indeed, there appears to be an ad hoc, reactionary approach to creating economic arguments for or against the design, installation or maintenance of natural elements such as green walls, green roofs, streetscapes, and parklands. With this issue in mind, this paper will overview research as part of an industry collaborative research project that considers the potential for using a number of environmental economic valuation techniques that have evolved over the last several decades in agricultural and resource economics, to systematically value the economic value of biophilic elements in the urban context. Considering existing literature on environmental economic valuation techniques, the paper highlights opportunities for creating a standardised language for valuing biophilic elements. The conclusions have implications for expanding the field of environmental economic value to support the economic evaluations and planning of the greater use of natural elements in cities. Insights are also noted for the more mature fields of agricultural and resource economics