Resumen: El objetivo de este breve trabajo es dar noticia de un interesante viaje a España del explorador escocés James Bruce, aportar información bibliográfica sobre unos manuscritos poco conocidos en España, e invitar a los investigadores a profundizar en el conocimiento de la España del siglo XVIII vista por los ojos de un viajero de la talla de James Bruce.
Resumen: It is well-known that quasi-isometrics between R-trees induce power quasi-symmetric homeomorphisms between their ultrametric end spaces. This paper investigates power quasi-symmetric homeomorphisms between bounded, complete, uniformly perfect, ultrametric spaces (i.e., those ultrametric spaces arising up to similarity as the end spaces of
bushy trees). A bounded distortion property is found that characterizes power quasi-symmetric homeomorphisms between such ultrametric spaces that are also pseudo-doubling. Moreover, examples are given showing the extent to which the power quasi-symmetry of homeomorphisms is not captured by the quasiconformal and bi-Holder conditions for this class of ultrametric spaces.
Palabras clave: Tree; real tree; bushy tree; ultrametric; end space; quasi-isometry; quasiconformal; quasi-symmetric; PQ-symmetric; doubling metric space
Resumen: Value-at-Risk (VaR) is commonly used for financial risk measurement. It has recently become even more important, especially during the 2008-09 global financial crisis. We pro-pose some novel nonlinear threshold conditional autoregressive VaR (CAViaR) models that incorporate intra-day price ranges. Model estimation and inference are performed using the Bayesian approach via the link with the Skewed-Laplace distribution.
We examine how a range of risk models perform during the 2008-09 fnancial crisis, and evaluate how the crisis afects the performance of risk models via forecasting VaR. Empirical analysis is conducted
on five Asia-Pacific Economic Cooperation stock market indices as well as two exchange rate series. We examine violation rates, back-testing criteria, market risk charges and quantile loss function values to measure and assess the forecasting performance of a variety of risk models. The proposed threshold CAViaR model, incorporating range information, is shown to forecast VaR more eficiently than other models, across the series considered, which should
be useful for financial practitioners.
Resumen: A genome-wide search using major histocompatibility complex (MHC) class I binding and proteosome cleavage site algorithms identified 101 influenza A PR8 virus-derived peptides as potential epitopes for CD8+ T cell recognition in the H-2b mouse. Cytokine-based flow cytometry, ELISPOT, and cytotoxic T lymphocyte assays reveal that 16 are
recognized by CD8+ T cells recovered directly ex vivo from infected animals, accounting for greater than 70% of CD8+ T cells recruited to lung after primary infection. Only six of the 22 highest affinity MHC class I binding peptides comprise cytotoxic T lymphocyte epitopes. The remaining non-immunogenic peptides have equivalent MHC affinity and MHC-peptide complex half-lives, eliciting T cell responses when given in adjuvant and with T cell receptor-ligand avidity comparable with their immunogenic counterparts. As revealed by a novel high sensitivity nanospray tandem mass spectrometry methodology, failure to process those predicted epitopes may contribute significantly to the absent response. These results have important implications for rationale design of CD8+ T cell vaccines.
Resumen: The Permian alkaline lamprophyres from the Spanish Central System (SCS) are highly porphyritic rocks which carry
a heterogeneous population of clinopyroxene and kaersutite zoned phernocrysts. Clinopyroxene phenocrysts may show 1) normal
zoning (Cpx-I), 2) reverse zoning with Fe-rich green cores (Cpx-II), and 3) reverse zoning with colourless Al-poor,
(Cpx-III). Kaersutite phenocrysts also show a slight reverse zoning. Major and trace element composition of Cpx-I suggests that
their compositional variation is related to a crystal fractionation process from melts similar to the host lamprophyres. The Cpx-II
cores represent crystallization from highly evolved melts (low Mg-Cr contents and incompatible element enrichment), genetically
related with the SCS alkaline magmatism, and the growth or surrounding Mg-rich inner rims points to a magma mixing process.
The major and trace element composition of Cpx-III cores supports derivation from a magma which has fractionated plagioclase.
This characteristic, together with their similarities when compared to clinopyroxenes from charnockite xenoliths, suggests that
they might be xenocrysts from deep calc-alkaline cumulates. The composition of melts in equilibrium with clinopyroxene and
amphibole phenocrysts supports a model in which Cpx-II and Cpx-III cores would have been incorporated into a more primitive
lamprophyric magma stagnated at lower crustal levels. The low pressure composition of all phenocryst outer rims indicates that
they crystallised directly from the host alkaline magma at their subvolcanic emplacement levels.