Resolving the Timing of Late Pleistocene Dome Emplacement at Mono Craters, California, from U–Th and Ar/Ar Dating

The Mono Craters chain in eastern California is one of the youngest sites of rhyolitic volcanism in North America and comprises at least 28 overlapping lava domes, flows, and tephra rings of mostly Holocene age. New U-series and 40Ar/39Ar geochronological data presented here extend the age of the Mono Craters into the Late Pleistocene. Ion microprobe 238U–230Th isochron dating of unpolished rims of allanite and zircon and 40Ar/39Ar laser fusion and step-heating dating of sanidine from the porphyritic biotite-bearing dome lavas of the Mono Craters yield Late Pleistocene ages, but the two techniques yield discordant results. The 238U–230Th isochron method gives ages of 26 ± 1.2 ka, 38 ± 1.2 ka, and 42 ± 1.1 ka for domes 31 (newly recognized), 24, and 19, respectively, whereas the corresponding 40Ar/39Ar sanidine ages are all older by an amount that exceed analytical errors. The anomalously older 40Ar/39Ar sanidine ages are attributed to excess argon from incompletely degassed antecrysts and/or melt inclusions trapped in juvenile phenocrysts. Explosive eruptions preceded dome emplacement and produced tephra layers in the Wilson Creek formation of ancestral Mono Lake. The independently dated tephra layers can be correlated to the domes via titanomagnetite geochemistry. Correlation of specific tephras to the domes verifies that the 238U–230Th isochron rim ages of euhedral zircon and allanite provide the best estimates of eruption ages for the Mono Craters

L'Au del paradís en la cultura visual moderna

Este artículo está sujeto a una licencia CC BY-NC-ND 3.0Peer reviewe

On a homeomorphism between orbit spaces of linear systems and matrix polynomials

AbstractThe orbit space of controllable systems under system similarity and the orbit space of matrix polynomials with determinant degree equal to the order of the state matrix under right equivalence are proved to be homeomorphic when the quotient compact–open topology is considered in the latter. As a consequence, the variation of the finite and left Wiener–Hopf structures under small perturbations of matrix polynomials with fixed degree for their determinants is described

Velázquez, ingenioso : intertextuality and biographical artifice in early modern Spanish artistic writing

Funding: The research for this article was supported by the European Research Council under the European Union’s Seventh Framework Programme (FP/2007–2013)/ERC grant agreement No. 617391.Focusing on the figure of Diego Velázquez, this article examines the significance of the notion of ingenio in early modern Spanish writings about painting. First, it considers its relevance to discussions about natural talent, including the links with treatises like Examen de ingenios. Second, it shows how the adoption of ingenio as a motif in two biographies of the young Velázquez contributed to the crafting of a contrived narrative on the artist, privileging his giftedness and independence. Third, it considers other articulations of this rhetoric of ingenio in relation to Velázquez’s art, particularly regarding matters of practice and skill.Publisher PDFPeer reviewe

Local Wiener–Hopf factorization and indices over arbitrary fields

AbstractIn this paper, a generalization to arbitrary fields of the usual Wiener–Hopf equivalence of complex valued rational matrix functions is given and the left local Wiener–Hopf factorization indices defined in our previous work [A. Amparan, S. Marcaida, I. Zaballa, Local realizations and local polynomial matrix representations of systems, Linear Algebra Appl. 425 (2007) 757–775] are proved to form a complete system of invariants for this equivalence relation. For the case when the field is algebraically closed a reduced form of a controllable matrix pair under the feedback equivalence is presented for which the controllability indices can be written as sums of the local controllability indices [A. Amparan, S. Marcaida, I. Zaballa, On the existence of linear systems with prescribed invariants for system similarity, Linear Algebra Appl. 413 (2006) 510–533]

Estudio geológico del área de Peñacerrada (Alava) : petrografía y cristalografía de las silificaciones existentes

El estudio geológico de la zona de Peñacerrada (Alava) pone de manifiesto la existencia de diversas silicificaciones en el Dogger (Jurásico) y en el Thanetiense (Paleoceno). Se han levantado columnas estratigráficas en tres localidades: Montoria, Arroyo de Santiama (Peñacerrada) y Loza, habiéndose realizado una recogida de muestras sistemáticas tanto de la "roca caja" como de las silicificaciones, para poder establecer las posibles relaciones existentes entre las mismas. La fuente de la sílice probablemente sea biogénica debido a la presencia de espículas de esponjas. El ambiente de depósito de los sedimentos carbonatados del Dogger se debió producir en una plataforma de mar abierto (nerítica), mientras que los del Thanetiense lo hicieron en un "lagoon" de circulación restringuida. En este último ambiente los vaivenes de la línea de costa crearon secuencias de somerización hacia arriba "shallowing upward" donde la mezcla de aguas continentales y marinas jugaron un papel importante tanto para la formación de las silicificaciones como para la dolomitización observada en la localidad de Loza. Se han diferenciado cuatro tipos generales de silicificaciones: cuarzos autigénicos, silicificaciones en nódulos, silicificaciones irregulares y silicificaciones en bancos lenticulares. El estudio de la Cristalografía-Mineralogía de los sílex de las tres localidades confirma en líneas generales la dependencia existente entre los valores de cristalinidad (I.C.G.) en el sentido de que a mayor volumen de celda le corresponde una disminución de la cristalinidad. Esto se observa siempre que los datos obtenidos se comparen con valores de otros sílex de la Cuenca, ya que la misma naturaleza de los sílex aquí estudiados (microcuarzo) hace que las diferencias en cuanto al volumen de Celda e I.C.G. de los mismos no sean muy significativasThe geological study of the Peñacerrada (Alava) area shows the existence of different types of silicification in the Dogger (Jurassic) Age and in the Thanetian (Paleocene) Age. We have drawn stratigraphic sections in three places: Montoria, Arroyo de Santiama (Peñacerrada) and Loza, with relations between them. The silica soruce may be biogenci, because a big number of siliceous sponge spicules included in the nodular chert ara appreciated. The Dogger carbonate sediments were deposited in an open platform (neritic) while the Thanetian sediments were in a lagoon environment. The movements of the shoreface generated sequences of "shallowing upward" where the mixing continental and marine waters played an important role for silicification and dolomitization processes observed in Loza. We have differentiated foru types of general silicification: Äutigenic quartzs, nodular chert, irregular silidifications and lenticular chert bands. The Crystallographic and Mineralogic study of the cherts show the general relation between the Crystalinity index values of the cherts and the limestone or dolomitic replacement. The values obtained for the crystallinity and unit cell volume allows us to corfirm the inverse relation existing between the

Functionalization of Cu3BTC2@IL composites with Pd(II) for catalytic applications

Comunicación en forma de panel presentada en el congreso 2nd European Conference on Metal Organic Frameworks and Porous Polymers del 29 de octubre al 1 denoviembre de 2017 en Delft, HolandaMetal-organic frameworks could be excellent supports for active catalytic species in order to obtain heterogeneous and reusable catalysts, easily removable from the reaction media.[1,2] Additionally, the presence of unsaturated metal centres in their pores provides a superb opportunity to tackle with reactions that requires more than one type of metal centre.[3] In order to obtain heterometallic catalyst we have immobilized Pd(II) into the pores of the well studied Cu3BTC2 MOF (BTC= benzene-1,3,5-tricarboxilate) with the help of imidazolium derivated ionic liquids (IL). The preparation of the catalyst was made in two steps. Firstly, the Cu3BTC2 was charged with [BMIM][BF4] and [BMIM][PF6] ionic liquids(BMIM= 1-Butyl-3-methylimidazolium). The stability of the composite materials, both chemical and thermal, was studied. Then, the insertion of palladium was made in basic media. By means of EDX the presence of Pd into the structural pores was proved and the quantification was made by ICP-AES. The powder DRX of the Cu3BTC2@[BMIM][Cation]-Pd samples show no structural changes with respect to the pristine Cu3BTC2. The functionalized material was tested as heterogeneous catalyst for Suzuki-Miyaura coupling reactions. The reactions were made in methanol at 70 ºC and using K2CO3 as base. The Pd:substrate molar ratio was set at 0.1 %. The activity was firstly studied using 4-bromotoluene and phenylboronic acid as reagents. The total conversion of the reaction reached 91 % in 1.5 hours with a selectivity towards the cross-coupling product of 67 %. Afterwards, other substrates were tested to study the scope of the reaction. When using 4-bromoanisole and phenylboronic acid, 67% of conversion was reached after 4 hours with a 100 % of selectivity towards the cross-coupling product. References: [1] P. Valvekens, F. Vermoortele and D. D. Vos, Catal. Sci. Technol., 2013, 3, 1435–1445. [2] E. S. Larrea, R. Fernández de Luis, J. Orive, M. Iglesias and M. I. Arriortua, Eur. J. Inorg. Chem., 2015, 2015, 4699–4707. [3] D. Saha, R. Sen, T. Maity and S. Koner, Langmuir, 2013, 29, 3140–3151

Correspondencia inédita de José Mª Lacoizqueta

El trabajo trata de mostrar una faceta poco conocida, hasta este momento, de la obra del botánico José María de Lacoizqueta: su relación epistolar con otros botánicos, entre ellos Miguel Colmeiro y Blas Lázaro e Ibiza, así como con el vascólogo Arturo Campión, explicándonos algunos aspectos de la génesis y redacción de su Diccionario de los nombres euskaros de las plantas (Pamplona, 1888). Por otro lado, gracias a estas cartas, sabemos más de la aportación de Lacoizqueta a la onomástica botánica en euskera que figura en la obra de Colmeiro.