Automorphisms of prime order of smooth cubic n-folds

In this paper we give an effective criterion as to when a prime number p is the order of an automorphism of a smooth cubic hypersurface of P^{n+1}, for a fixed n > 1. We also provide a computational method to classify all such hypersurfaces that admit an automorphism of prime order p. In particular, we show that p<2^{n+1} and that any such hypersurface admitting an automorphism of order p>2^n is isomorphic to the Klein n-fold. We apply our method to compute exhaustive lists of automorphism of prime order of smooth cubic threefolds and fourfolds. Finally, we provide an application to the moduli space of principally polarized abelian varieties.Comment: 10 page

Automorphisms of prime order of smooth cubic n -folds

In this paper we give an effective criterion as to when a prime number p is the order of an automorphism of a smooth cubic hypersurface of $${\mathbb{P}^{n+1}}$$ , for a fixed n ≥ 2. We also provide a computational method to classify all such hypersurfaces that admit an automorphism of prime order p. In particular, we show that p2 n is isomorphic to the Klein n-fold. We apply our method to compute exhaustive lists of automorphism of prime order of smooth cubic threefolds and fourfolds. Finally, we provide an application to the moduli space of principally polarized abelian varietie

On a Torelli Principle for automorphisms of Klein hypersurfaces

We compute all the remaining automorphism groups of Klein hypersurfaces of dimension n>0 and degree d>2 with (n,d) different from (2,4). We introduce the concept of extremal polarized Hodge structures, which are structures that admit an automorphism of large prime order. Using this notion, we compute the automorphism group of the rational polarized Hodge structure of certain Klein hypersurfaces that we call of Wagstaff type, which are characterized by the existence of an automorphism of large prime order. For cubic hypersurfaces and some other values of (n,d), we show that both groups coincide (up to involution) as predicted by the Torelli Principle.Comment: 21 page

Efecto alelopático de la invasora Acacia dealbata Link (Fabaceae) en dos especies de plantas nativas del centro-sur de Chile

Plant species that growth close to or under the canopy of Acacia dealbata Link (Fabaceae, subfamily: Mimosoideae) withinits non-native range, survive with difficulty or not at all, especially if they are native. This phenomenon has been attributedto allelopathy; one of the strategies used by A. dealbata to trigger an invasion process. Native species Quillaja saponariaMolina (tree) and Helenium aromaticum (Hook.) H.L. Bailey (herb), share A. dealbata’s range in South-central Chile. Thisstudy was performed on the Mediterranean Biobío Region of Chile. We evaluated the effect of leaves, flowers, pods andseeds of A. dealbata on the germination and early growth of these native species. Biological assays were carried out underlaboratory conditions, based on aqueous extracts and the direct effect of plant material. Leaf litter prevented the germinationof both species and seeds of the invasive species impeded the germination of Q. saponaria. Other plant parts from A.dealbata also induced reductions of hypocotyl and radicle lengths in the native species, reaching over 50 % in some treatmentvalues. All plant parts caused radicle necrosis, preventing the formation of root hairs and, consequently, jeopardizing thesurvival possibility of the recipient species. The results show that A. dealbata can interfere with the establishment of pioneerherbaceous species in ecological succession and can also affect trees if they are reached by the invasion front.Las plantas que crecen cerca o bajo el dosel de Acacia dealbata Link (Fabaceae, subfamilia: Mimosoideae), cuando esta seencuentra en el rango no nativo, sobreviven con dificultad o no lo logran, especialmente si son nativas. Este fenómeno se haatribuido a la alelopatía; una de las estrategias utilizadas por A. dealbata para promover su proceso de invasión. Las especiesnativas Quillaja saponaria Molina (arbórea) y Helenium aromaticum (Hook.) H.L. Bailey (herbácea) comparten el rango dedistribución de A. dealbata en el centro-sur de Chile. El presente trabajo se realizó en la Región del Biobío y se evaluaronlos efectos de hojas, flores, vainas y semillas de A. dealbata en la germinación y crecimiento temprano de las especiesnativas mencionadas. Los ensayos biológicos se llevaron a cabo en condiciones de laboratorio, basados en extractos acuososy efectos directos del material vegetal. Nuestros resultados indicaron que las hojas impidieron la germinación de ambasespecies nativas, pero las semillas impidieron sólo la germinación de Q. saponaria. Otras partes de la planta de A. dealbatatambién indujeron fuertes reducciones de las longitudes del hipocótilo y radícula en las especies nativas, superándose el50% en algunos tratamientos. Todas las partes de la planta causaron necrosis en la radícula, evitando la formación de pelosradicales y, por consiguiente, comprometiendo la posibilidad de supervivencia de las especies receptoras. Estos resultadosmuestran que A. dealbata puede interferir en el establecimiento de especies herbáceas pioneras en la sucesión ecológica ytambién puede afectar especies arbóreas secundarias si son alcanzadas por el frente de invasión

Simulación prospectiva del crecimiento urbano en la Comunidad Autónoma de Madrid a partir de modelos basados en autómatas celulares y modelos basados en EMC

En el presente trabajo se analizan los resultados de varias simulaciones prospectivas de crecimiento urbano, entre los años 2000 y 2020, realizadas en la Comunidad de Madrid, aplicando dos modelos diferentes: uno basado en Autómatas Celulares (AC) y otro en técnicas de Evaluación MultiCriterio (EMC). El objetivo es comparar los resultados de las simulaciones de ambos modelos para detectar si se aproximan o están fuertemente influidos por la técnica empleada. Esto también permitiría, en cierta forma, evaluar los modelos desarrollados y su utilidad, pudiendo generar una cartografía de los resultados más robustos, es decir, de localizaciones que reiteradamente aparecen en las distintas simulaciones como las más apropiadas para desarrollar una futura ocupación urbana. En este caso concreto, se ha podido comprobar la escasa coincidencia entre resultados, evidenciando la necesidad, por un lado, de utilizar metodologías de comparación de mapas más flexibles, que permitan valorar mejor las semejanzas/diferencias encontradas, y, por otro, de detectar particularidades de los modelos que estén condicionando los resultados e, inclusive, deficiencias en su desarrollo.Proyecto SIMURBAN2: Instrumentos de Geosimulación y planificación ambiental en la ordenación territorial de ámbitos metropolitanos. Aplicación a escalas intermedias (Ref.: CSO2012-38158-C02-01)

On the order of an automorphism of a smooth hypersurface

In this paper we give an effective criterion as to when a positive integer q is the order of an automorphism of a smooth hypersurface of dimension n and degree d, for every d>2, n>1, (n,d)\neq (2,4), and \gcd(q,d)=\gcd(q,d-1)=1. This allows us to give a complete criterion in the case where q=p is a prime number. In particular, we show the following result: If X is a smooth hypersurface of dimension n and degree d admitting an automorphism of prime order p then p(d-1)^n then X is isomorphic to the Klein hypersurface, n=2 or n+2 is prime, and p=\Phi_{n+2}(1-d) where \Phi_{n+2} is the (n+2)-th cyclotomic polynomial. Finally, we provide some applications to intermediate jacobians of Klein hypersurfaces

Influence of SC-HAZ microstructure on the mechanical behavior of Si-TRIP steel welds

Transformation induced plasticity (TRIP) steel provides enormous potential for auto-body construction in the automotive sector, owing to its enhanced mechanical behavior. In this work, Si-alloyed TRIP steel is joined by employing laser beam welding (LBW) and by utilizing two arc welding processes: gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) in order to assess the effect of the net heat input on the microstructure, the uniaxial tensile properties and the forming response. Results indicate that in spite of the Si content in TRIP steel; precipitation and growth of carbides (tempering) are observed in both: the martensite islands and the retained austenite phase, thus leading to the measurable softening at the sub-critical heat affected zone (SCHAZ) of the arc welded samples. Although the failure location was predominantly found at the sub-critical heat affected zone of the GMAW samples, the maximum stress and elongation was basically controlled by the total extension of the weldment including fusion zone and heat affected zone. While the limiting dome height upon tension-tension (T-T) and tension-compression (T-C) depended primarily on the fusion zone hardness, weld width and geometry of the sample; the fracture location was outside the weld for T-C, whereas the fracture initiated at the weld in T-T samples. LBW specimens showed optimum forming performance.Transformation induced plasticity (TRIP) steel provides enormous potential for auto-body construction in the automotive sector, owing to its enhanced mechanical behavior. In this work, Si-alloyed TRIP steel is joined by employing laser beam welding (LBW) and by utilizing two arc welding processes: gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) in order to assess the effect of the net heat input on the microstructure, the uniaxial tensile properties and the forming response. Results indicate that in spite of the Si content in TRIP steel; precipitation and growth of carbides (tempering) are observed in both: the martensite islands and the retained austenite phase, thus leading to the measurable softening at the sub-critical heat affected zone (SCHAZ) of the arc welded samples. Although the failure location was predominantly found at the sub-critical heat affected zone of the GMAW samples, the maximum stress and elongation was basically controlled by the total extension of the weldment including fusion zone and heat affected zone. While the limiting dome height upon tension-tension (T-T) and tension-compression (T-C) depended primarily on the fusion zone hardness, weld width and geometry of the sample; the fracture location was outside the weld for T-C, whereas the fracture initiated at the weld in T-T samples. LBW specimens showed optimum forming performance

Centro para el Estudio de la Interdependencia Provincial en la Antigüedad Clásica CEIPAC

En 1988 se creó, por primera vez, una cátedra de Historia Antigua en la Cataluña postguerra civil. La cátedra de Historia Antigua había sido asociada a la de Prehistoria, regida por el profesor. D. Joan Maluquer de Montes i Nicolau, quien no aprovechó la oportunidad de dividir ambas cátedras en el momento, en el que tanto la asignatura de Prehistoria como la de Historia Antigua se convirtieron en dos materias troncales en los planes de estudio