1,367 research outputs found
Algunos elementos de armamento de la Segunda Edad del Hierro localizados en prospección en Navarra
Se estudia un pequeño lote de elementos de equipamiento militar de la Segunda
Edad del Hierro. Todos ellos han sido localizados en prospección superficial en Navarra. Un
pomo de puñal -de cuerna- procede de El Dorre (Artajona) y puede fecharse dentro del siglo IV a.
de J.e. Parte de un vástago y de una punta de lanza - de hierro- y una escama de coraza -de
aleación de cobre- proceden de Cabezo Lobo (Bardenas Reales) y podrían fecharse en el siglo 11 a.
de J.e. o a finales del anterior
La necrópolis de San Pelayo (Alegría-Dulantzi, Álava) y la cuestión de la fecha de inicio de las necrópolis de tipo merovingio en Álava
En este artículo se discute, fundamentalmente, la fecha de establecimiento de
las dos necrópolis de tipo merovingio descubiertas, por el momento, en Álava.
De las evidencias publicadas hasta ahora por su excavador, A. Azkarate, parece
desprenderse para Aldaieta (Nanclares de Gamboa) un inicio durante la primera mitad del siglo
VI de J.e. Ligeramente más antigua parece la de San Pelayo (Alegría), fechada por la presencia
de TSHT en sus ajuares a comienzos del mismo siglo.
De esa manera, resulta factible conectar el origen de un área dependiente del reino franco en
la zona occidental al sur de los Pirineos con el hundimiento del reino visigodo de Tolosa tras la
batalla de Vouillé
Algunos elementos de cultura material tardorromana procedentes de la "Villa" de San Blas (Olite, Navarra)
Se estudia un pequeño lote de materiales de fecha tardorromana (mediados del
siglo IV, siglo V de J.C.) procedentes de la villa de San Blas (Olite). Se trata de fragmentos de DS-
P gris (representadas las formas la, 5b, 15 y 18b), un huso de hierro y un recipiente de chapa de
bronce. Tanto el plato D-S-P la, como el huso y el recipiente de bronce, pudieran provenir de un
contexto funerario
Protein aggregates nucleate ice: the example of apoferritin
Biological material has gained increasing attention recently as a source of ice-nucleating particles that may account for cloud glaciation at moderate supercooling. While the ice-nucleation (IN) ability of some bacteria can be related to membrane-bound proteins with epitaxial fit to ice, little is known about the IN-active entities present in biological material in general. To elucidate the potential of proteins and viruses to contribute to the IN activity of biological material, we performed bulk freezing experiments with the newly developed drop freezing assay DRoplet Ice Nuclei Counter Zurich (DRINCZ), which allows the simultaneous cooling of 96 sample aliquots in a chilled ethanol bath. We performed a screening of common proteins, namely the iron storage protein ferritin and its iron-free counterpart apoferritin, the milk protein casein, the egg protein ovalbumin, two hydrophobins, and a yeast ice-binding protein, all of which revealed IN activity with active site densities > 0.1 mg−1 at −10 ∘C. The tobacco mosaic virus, a plant virus based on helically assembled proteins, also proved to be IN active with active site densities increasing from 100 mg−1 at −14 ∘C to 10 000 mg−1 at −20 ∘C. Among the screened proteins, the IN activity of horse spleen ferritin and apoferritin, which form cages of 24 co-assembled protein subunits, proved to be outstanding with active site densities > 10 mg−1 at −5 ∘C. Investigation of the pH dependence and heat resistance of the apoferritin sample confirmed the proteinaceous nature of its IN-active entities but excluded the correctly folded cage monomer as the IN-active species. A dilution series of apoferritin in water revealed two distinct freezing ranges, an upper one from −4 to −11 ∘C and a lower one from −11 to −21 ∘C. Dynamic light scattering measurements related the upper freezing range to ice-nucleating sites residing on aggregates and the lower freezing range to sites located on misfolded cage monomers or oligomers. The sites proved to persist during several freeze–thaw cycles performed with the same sample aliquots. Based on these results, IN activity seems to be a common feature of diverse proteins, irrespective of their function, but arising only rarely, most probably through defective folding or aggregation to structures that are IN active.This research has been supported by the Swiss National Foundation (grant nos. IZSEZ0_179149/1 and 200021_156581), the Basque government (Elkartek programmes ng 15 and ng 17), and the Spanish MINECO (grant no. MAT2013- 46006-R, programme MDM-2016-0618)
Experimental test of a trace formula for two-dimensional dielectric resonators
Resonance spectra of two-dimensional dielectric microwave resonators of
circular and square shapes have been measured. The deduced length spectra of
periodic orbits were analyzed and a trace formula for dielectric resonators
recently proposed by Bogomolny et al. [Phys. Rev. E 78, 056202 (2008)] was
tested. The observed deviations between the experimental length spectra and the
predictions of the trace formula are attributed to a large number of missing
resonances in the measured spectra. We show that by taking into account the
systematics of observed and missing resonances the experimental length spectra
are fully understood. In particular, a connection between the most long-lived
resonances and certain periodic orbits is established experimentally.Comment: 14 pages, 12 figures, 1 tabl
Enhancement of photoacoustic detection of inhomogeneities in polymers
We report a series of experiments on laser pulsed photoacoustic excitationin
turbid polymer samples addressed to evaluate the sound speed in the samples and
the presence of inhomogeneities in the bulk. We describe a system which allows
the direct measurement of the speed of the detected waves by engraving the
surface of the piece under study with a fiduciary pattern of black lines. We
also describe how this pattern helps to enhance the sensitivity for the
detection of an inhomogeneity in the bulk. These two facts are useful for
studies in soft matter systems including, perhaps, biological samples. We have
performed an experimental analysis on Grilon(R) samples in different situations
and we show the limitations of the method.Comment: 8 pages, 7 figure
Revisión de los elementos de ajuar conservados del sepulcro megalítico de Unón (Clavijo, La Rioja)
En este artículo se procede a la revisión de los materiales conservados del
megalito desaparecido de Uñón (Clavijo, La Rioja), entre los que destacan varios recipientes campaniformes
Zooplankton variability at four monitoring sites of the Northeast Atlantic shelves differing in latitude and trophic status
Zooplankton abundance series (1999–2013) from the coastal sites of Bilbao 35 (B35), Urdaibai 35 (U35), Plymouth
L4 (L4) and Stonehaven (SH), in the Northeast Atlantic were compared to assess differences in the magnitude of
seasonal, interannual and residual scales of variability, and in patterns of seasonal and interannual variation in relation
to latitudinal location and trophic status. Results showed highest seasonal variability at SH consistent with its
northernmost location, highest interannual variability at U35 associated to an atypical event identified in 2012 in
the Bay of Biscay, and highest residual variability at U35 and B35 likely related to lower sampling frequency and
higher natural and anthropogenic stress. Interannual zooplankton variations were not coherent across sites, suggesting
the dominance of local influences over large scale environmental drivers. For most taxa the seasonal pattern
showed coherent differences across sites, the northward delay of the annual peak being the most common feature.
The between-site seasonal differences in spring–summer zooplankton taxa were related mainly to phytoplankton
biomass, in turn, related to differences in latitude or anthropogenic nutrient enrichment. The northward delay in
water cooling likely accounted for between-site seasonal differences in taxa that increase in the second half of
the year
Genomic variation and population structure detected by single nucleotide polymorphism arrays in Corriedale, Merino and Creole sheep.
THE AIM OF THIS STUDY WAS TO INVESTIGATE THE GENETIC DIVERSITY WITHIN AND AMONG THREE BREEDS OF SHEEP: Corriedale, Merino and Creole. Sheep from the three breeds (Merino n = 110, Corriedale n = 108 and Creole n = 10) were genotyped using the Illumina Ovine SNP50 beadchip(®). Genetic diversity was evaluated by comparing the minor allele frequency (MAF) among breeds. Population structure and genetic differentiation were assessed using STRUCTURE software, principal component analysis (PCA) and fixation index (FST). Fixed markers (MAF = 0) that were different among breeds were identified as specific breed markers. Using a subset of 18,181 single nucleotide polymorphisms (SNPs), PCA and STUCTURE analysis were able to explain population stratification within breeds. Merino and Corriedale divergent lines showed high levels of polymorphism (89.4% and 86% of polymorphic SNPs, respectively) and moderate genetic differentiation (FST = 0.08) between them. In contrast, Creole had only 69% polymorphic SNPs and showed greater genetic differentiation from the other two breeds (FST = 0.17 for both breeds). Hence, a subset of molecular markers present in the OvineSNP50 is informative enough for breed assignment and population structure analysis of commercial and Creole breeds
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