Information Transmission around Block Trades on the Spanish Stock Market.

This study investigates the informational effects of large transactions, or Block Trades (BT), in the Spanish Stock Exchange (SSE). In the open market period, this topic was not facilitated in the SSE as it was in other markets until 1998. The SSE thus provides a special environment for analysing the information transmission of these specific transactions. It is assumed that information can be better reflected by changes in true asset value, proxied by the midpoint of bid-ask best quotes. Therefore, we will look at changing true asset value orders instead of trades. Three different effects are studied around BTs: price, liquidity and information transmission. To capture them, three different endogenous variables are considered: true asset returns, relative spreads and adverse selection spread component. With this approach, no clear effects of BTs are found. The main result of the study is that there seems to be an increase in information asymmetries when one looks at the adverse selection spread component in some of the different subsample classifications (buyer, seller and sweeping BT), but there is no significant permanent effect on returns. This result could be related to insiders trading in the market. In sharp contrast with adverse selection evidence, a temporary decrease in bid/ask spread around BTs is also observed. These changes reflect temporary liquidity effects related to other spread components (order processing costs and inventory costs).

Information transmission around block trades on the Spanish stock market

Current fmancial research is placing increasing attention on the effects of large transactions, or Block Trades (BT), on the fmancial markets. In order to analyze whether BT transmit information, we assume that information can be better reflected by changes in asset true value, proxied by the midpoint of bid-ask best quotes, instead of transactions prices or returns. Moreover, following market microstructure literature, we also look at changes in relative spread and in their adverse selection component. The Madrid Stock Exchange offers us a particularly appropriate testing ground for examining these issues, since this topic has not been facilitated as in other markets till 1998. We analyze 195 BT, classified according with trading volume, the side of the market initiating the BT (buyer, seller or indeterminate initiated), its type (inside the spread, sweeping or not classified) and if they change or not the asset true value. The main result of the paper is that it seems that there is BT information transmission when we look at adverse selection spread component in the different subsample classification, but there is no significant permanent effect in returns. We also observe changes in liquidity around BTs but the effect is related with temporary spread component

Infrared Spectral Energy Distributions of Seyfert Galaxies: Spitzer Space Telescope Observations of the 12 micron Sample of Active Galaxies

The mid-far-infrared spectral energy distributions (SEDs) of 83 active galaxies, mostly Seyfert galaxies, selected from the extended 12 micron sample are presented. The data were collected using all three instruments, IRAC, IRS, and MIPS, aboard the Spitzer Space Telescope. The IRS data were obtained in spectral mapping mode, and the photometric data from IRAC and IRS were extracted from matched, 20 arcsec diameter circular apertures. The MIPS data were obtained in SED mode, providing very low resolution spectroscopy (R ~ 20) between ~ 55 and 90 microns in a larger, 20 by 30 arcsec synthetic aperture. We further present the data from a spectral decomposition of the SEDs, including equivalent widths and fluxes of key emission lines; silicate 10 and 18 micron emission and absorption strengths; IRAC magnitudes; and mid-far infrared spectral indices. Finally, we examine the SEDs averaged within optical classifications of activity. We find that the infrared SEDs of Seyfert 1s and Seyfert 2s with hidden broad line regions (HBLR, as revealed by spectropolarimetry or other technique) are qualitatively similar, except that Seyfert 1s show silicate emission and HBLR Seyfert 2s show silicate absorption. The infrared SEDs of other classes with the 12 micron sample, including Seyfert 1.8-1.9, non-HBLR Seyfert 2 (not yet shown to hide a type 1 nucleus), LINER and HII galaxies, appear to be dominated by star-formation, as evidenced by blue IRAC colors, strong PAH emission, and strong far-infrared continuum emission, measured relative to mid-infrared continuum emission.Comment: 78 pages, 13 figure

Whole-mount three-dimensional imaging of internally localized immunostained cells within mouse embryos

We describe a three-dimensional (3D) confocal imaging technique to characterize and enumerate rare, newly emerging hematopoietic cells located within the vasculature of whole-mount preparations of mouse embryos. However, the methodology is broadly applicable for examining the development and 3D architecture of other tissues. Previously, direct whole-mount imaging has been limited to external tissue layers owing to poor laser penetration of dense, opaque tissue. Our whole-embryo imaging method enables detailed quantitative and qualitative analysis of cells within the dorsal aorta of embryonic day (E) 10.5-11.5 embryos after the removal of only the head and body walls. In this protocol we describe the whole-mount fixation and multimarker staining procedure, the tissue transparency treatment, microscopy and the analysis of resulting images. A typical two-color staining experiment can be performed and analyzed in ∼6 d

Erythroid/myeloid progenitors and hematopoietic stem cells originate from distinct populations of endothelial cells

SummaryHematopoietic stem cells (HSCs) and an earlier wave of definitive erythroid/myeloid progenitors (EMPs) differentiate from hemogenic endothelial cells in the conceptus. EMPs can be generated in vitro from embryonic or induced pluripotent stem cells, but efforts to produce HSCs have largely failed. The formation of both EMPs and HSCs requires the transcription factor Runx1 and its non-DNA binding partner core binding factor β (CBFβ). Here we show that the requirements for CBFβ in EMP and HSC formation in the conceptus are temporally and spatially distinct. Panendothelial expression of CBFβ in Tek-expressing cells was sufficient for EMP formation, but was not adequate for HSC formation. Expression of CBFβ in Ly6a-expressing cells, on the other hand, was sufficient for HSC, but not EMP, formation. The data indicate that EMPs and HSCs differentiate from distinct populations of hemogenic endothelial cells, with Ly6a expression specifically marking the HSC-generating hemogenic endothelium

Presión sobre los precios en las revisiones del índice IBEX35

Este trabajo analiza el efecto de las redefiniciones del índice Ibex35 en los precios y la actividad de negociación de las acciones incluidas y excluidas. La muestra utilizada está formada por 26 entradas y 22 salidas estables en el periodo enero 1991-diciembre 1998. Los resultados obtenidos demuestran que las revisiones del Ibex35 provocan una importante reacción positiva (negativa)en el precio de las acciones que entran (salen), fundamentalmente en el día siguiente al anuncio de la medida y en la fecha anterior a la recomposición efectiva del indicador. Las rentabilidades anormales positivas (negativas)generadas no están relacionadas con información acerca de las perspectivas futuras de las empresas afectadas ni con medidas de cambio de liquidez. Con posterioridad al cambio efectivo los precios experimentan un proceso de reversión parcial (completo) a sus niveles previos en las entradas (salidas). En conjunto, la evidencia obtenida apoya la hipótesis de presión sobre los precios como explicación de los efectos provocados por las revisiones en la composición del Ibex35. (Copyright: Fundación SEPI)Revisión de índices, efectos precio y volumen, presión sobre los precios.

Indeterminación semántico-sintáctica en el discurso jurídico civil

The close relationship between the semantic and syntactic elements of legal discourse implies the handling of a specific terminology, which, without being eminently lexical, is adequately combined with technolects, connectors and deontic operators for the full interpretation of its sense and meaning. so that ambiguities are avoided. In this perspective, the norms contained in books IV, V and VI of the Peruvian Civil Code have been analyzed. The analysis has been carried out based on norms of standard articles, in terms of structure and significance of the legal norm, which has made it easier to specify elements of semantic-syntactic indeterminacy that show ambiguities, incorrect use of punctuation marks and inappropriate use of connectors. "e" and "and". The most relevant conclusions reached are: the elements of semantic-syntactic indeterminacy in the Peruvian civil legal norm lead to the unilateral interpretation of the norm for its application, generating discrepancies in the light of jurisprudence and legal pragmatics and the relationship semantic-syntactic present in the legal norm implies the individual knowledge of the words, in terms of their sense and meaning of the discursive context in which it is used.La estrecha relación entre los elementos semánticos y sintácticos del discurso jurídico, implica el manejo de una terminología específica, que, sin ser eminentemente lexical, se combine adecuadamente con los tecnolectos, los conectores y los operadores deónticos para la interpretación cabal de su sentido y significado, de modo que se eviten ambigüedades. En esa perspectiva, se han analizado las normas contenidas en los libros IV, V y VI del Código Civil Peruano. El análisis se ha realizado en base a normas de artículos tipo, en cuanto estructura y significación de la norma jurídica, lo cual ha facilitado precisar elementos de indeterminación semántico-sintáctica que evidencian ambigüedades, uso incorrecto de signos de puntuación y uso inapropiado de los conectores “e” e “y”. Las conclusiones más relevantes a las cuales se arribó son: los elementos de indeterminación semántico-sintáctica en la norma jurídica civil peruana inducen a la interpretación unilateral de la norma para su aplicación, generando discrepancias a la luz de la jurisprudencia y pragmática jurídica y la relación semántico- sintáctica presente en la norma jurídica implica el conocimiento individual de las palabras, en cuanto su sentido y significado del contexto discursivo en el cual se usa

Changements de la distribution de la variance génétique d’un caractère quantitatif dans des populations d’effectif limité de Drosophlla melanogaster

10 Pags.- 3 Tabls.[EN] The coefficient of variation of the genetic variance at generation t, C)AV,t(V of an additive trait among replicated unselected small populations has been theoretically shown to be largely due to linkage disequilibrium from sampling. Starting from a population in linkage equilibrium, CA)Vt(V should initially increase, rapidly approaching an asymptotic value. However, when effective population size expands, CV(V At) is expected to decrease. Experiments with Drosophila melanogaster were carried out to check these predictions. Inbred lines were established by brother-sister single pair matings and continued for 3 generations. Each line was then maintained with as many parents as possible up to generation 10. The trait considered was the total number of abdominal bristles on the 5th and the 6th stemites, in generations 0, 4 and 10. A single generation of divergent selection was carried out in each of 75 lines in the same generations. Assuming no differences in environmental variance between lines, CA)Vt(V can then be estimated from the within-line phenotypic variances or from the responses to selection. As predicted by theory, the value of CV(VA!) substantially increased from generation 0 to 4. No reduction was detected afterwards, possibly because the trait was affected by blocks of genes. Other predictions made concerning the redistribution of the genetic variance have been substantiated.[FR] On a montré théoriquement que le coefficient de variation de la variance génétique d’un caractère additif dans la génération t, C)AV(,tV dans un ensemble de lignées non sélectionnées ayant toutes le même effectif génétique, est dû essentiellement au déséquilibre de linkage" généré par échantillonnage. Si la population est initialement en équilibre, CA)V(tV s accroit au fil des générations, tendant rapidement vers une valeur asymptotique. Si, ensuite, l’effectif de la population augmente, CA)V(lV diminuera. Afin de confro"ler ces prédictions, on a réalisé des accouplements consanguins frère x sceur, pendant 3 générations dans un ensemble de lignées de Drosophila melanogaster. Postérieurement chaque lignée a été maintenue jusqu’à la génération 10 avec le plus grand nombre possible de géniteurs. Le caractère considéré a été le nombre total de soies dans les 5Q et 60 segments abdominaux, évalué dans les générations 0, 4 et 10. Parallèlement, et dans ces mêmes générations, on a effectué une sélection divergente pendant une génération en 75 lignées. En supposant que la variance environnementale du caractère soit la même dans toutes les lignées considérées, CA)V(tV peut être évalué à partir des variances phénotypiques intra-lignée ou à partir des réponses à la sélection. La valeur de CA)V(tV a augmenté considérablement en passant de la génération 0 à la 4, ainsi que le prévoyait la théorie. Toutefois, elle ne s’est pas réduite ensuite, ce qui est probablement dû à l’existence de blocs géniques. Les prédictions théoriques relatives à la redistribution de la variance génétique ont été également vérifiées.his work was supported by a grant from Comision Asesora de Investigacion Cientifica y Técnica.Peer reviewe