Cyclic behaviour of Volterra composition operators

We determine the cyclic behaviour of Volterra composition operators, which are defined as $(V_\phif)(x) =\int_0^{\phi(x)}f(t) dt$, $f ? L^p[0, 1]$, 1\leq p <\infty$,
where $?$ is a measurable self-map of [0, 1]. The cyclic behaviour of $V_\phi$ is essentially determined by the behaviour of the inducing symbol $\phi$ at 0 and at 1. As a particular result, we provide new examples of quasinilpotent supercyclic operators, which extend and complement previous ones of Hector Salas.

The Early Asymmetries of Supernova 2008D/XRF 080109

Spectropolarimetry of the Type Ib SN 2008D, associated with the X-ray Flash (XRF) 080109, at two separate epochs, is presented. The epochs of these observations correspond to V-band light curve maximum and 15 days after light curve maximum (or 21 and 36 days after the XRF). We find SN 2008D to be significantly polarized, although the largest contribution is due to the interstellar polarization component of Q ISP = 0% ± 0.1% and U ISP = -1.2% ± 0.1%. At the two epochs, the spectropolarimetry of SN 2008D is classified as being D1+L(He I)+L(Ca II). The intrinsic polarization of continuum wavelength regions is <0.4%, at both epochs, implying an asymmetry of the photosphere of <10%. Similar to other Type Ibc SNe, such as 2005bf, 2006aj, and 2007gr, we observed significant polarization corresponding to the spectral features of Ca II, He I, Mg I, Fe II and, possibly, O I ?7774, about a close-to-spherically symmetric photosphere. We introduce a new plot showing the chemically distinct line-forming regions in the ejecta and comment on the apparent ubiquity of highly polarized high-velocity Ca II features in Type Ibc SNe. The polarization angle of Ca II IR triplet was significantly different, at both epochs, to those of the other species, suggesting high-velocity Ca II forms in a separate part of the ejecta. The apparent structure in the outer layers of SN 2008D has implications for the interpretation of the early-time X-ray emission associated with shock breakout. We present two scenarios, within the jet-torus paradigm, which explain the lack of an apparent geometry discontinuity between the two observations: (1) a jet which punched a hole straight through the progenitor and deposited Ni outside the ejecta and (2) a jet which stalled inside the radius of the photosphere as observed at the second epoch. The lack of a peculiar polarization signature, suggesting strongly asymmetric excitation of the ejecta, and the reported properties of the shock-breakout favor the second scenario.

The Unification of Asymmetry Signatures of Type Ia Supernovae

We present a compilation of the geometry measures acquired using optical and IR spectroscopy and optical spectropolarimetry to probe the explosion geometry of Type Ia supernovae (SNe Ia). Polarization measurements are sensitive to asymmetries in the plane of the sky, whereas line profiles in nebular phase spectra are expected to trace asymmetries perpendicular to the plane of the sky. The combination of these two measures can overcome their respective projection effects, completely probing the structures of these events. For nine normal SNe Ia, we find that the polarization of Si II ?6355 at 5 days before maximum (p Si II ) is well correlated with its velocity evolution (\dot{v}_Si II), implying that \dot{v}_Si II is predominantly due to the asymmetry of the SNe. We find only a weak correlation between the polarization of Si II and the reported velocities (v neb) for peak emission of optical Fe II and Ni II lines in nebular spectra. Our sample is biased, with polarization measurements being only available for normal SNe that subsequently exhibited positive (i.e., redshifted) v neb. In unison these indicators are consistent with an explosion in which the outer layers are dominated by a spherical oxygen layer, mixed with an asymmetric distribution of intermediate-mass elements. The combination of spectroscopic and spectropolarimetric indicators suggests a single geometric configuration for normal SNe Ia, with some of the diversity of observed properties arising from orientation effects.

Genome scan meta-analysis of schizophrenia and bipolar disorder, part II:Schizophrenia

Schizophrenia is a common disorder with high heritability and a 10-fold increase in risk to siblings of probands. Replication has been inconsistent for reports of significant genetic linkage. To assess evidence for linkage across studies, rank-based genome scan meta-analysis (GSMA) was applied to data from 20 schizophrenia genome scans. Each marker for each scan was assigned to 1 of 120 30-cM bins, with the bins ranked by linkage scores (1 = most significant) and the ranks averaged across studies (R(avg)) and then weighted for sample size (N(sqrt)[affected casess]). A permutation test was used to compute the probability of observing, by chance, each bin's average rank (P(AvgRnk)) or of observing it for a bin with the same place (first, second, etc.) in the order of average ranks in each permutation (P(ord)). The GSMA produced significant genomewide evidence for linkage on chromosome 2q (PAvgRnk

The PREDICTS database: a global database of how local terrestrial biodiversity responds to human impacts

Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species' threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project - and avert - future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups - including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems - http://www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015.

The timing and spatiotemporal patterning of Neanderthal disappearance

ThetimingofNeanderthal disappearanceandtheextent to whichthey overlapped with the earliest incoming anatomically modern humans (AMHs)inEurasia arekey questions inpalaeoanthropology1,2 .Deter- mining the spatiotemporal relationship between the two populations is crucial if we are to understand the processes, timing and reasons leading to the disappearance of Neanderthals and the likelihood of cultural and genetic exchange. Serious technical challenges, however, havehinderedreliable datingof the period,as theradiocarbonmethod reaches its limit at 50,000 years ago3 .Herewe apply improved accel- erator mass spectrometry 14C techniques to construct robust chro- nologies from 40 key Mousterian and Neanderthal archaeological sites, ranging fromRussia toSpain.Bayesianagemodellingwas used togenerate probability distributionfunctions todetermine the latest appearancedate.Weshowthat theMousterianendedby41,030–39,260 calibratedyears BP(at95.4%probability) acrossEurope.Wealsodem- onstrate that succeeding ‘transitional’ archaeological industries, one ofwhich has beenlinked withNeanderthals (Cha ˆtelperronian)4 ,end at a similar time. Our data indicate that the disappearance of Nean- derthals occurred at different times in different regions.Comparing the data with results obtained fromthe earliest datedAMHsites in Europe, associated with the Uluzzian technocomplex5 , allows us to quantify the temporal overlap between the two human groups. The results revealasignificantoverlap of 2,600–5,400years (at 95.4%prob- ability).This hasimportant implications formodels seeking toexplain the cultural, technological and biological elements involved in the replacement of Neanderthals byAMHs.Amosaic of populations in Europe during the Middle to Upper Palaeolithic transition suggests that there was ample time for the transmission of cultural and sym- bolic behaviours, as well as possible genetic exchanges, between the two groups.

Control of ionization and dissociation of H2+ by elliptically polarized ultra-short VUV laser pulses

Resonance-enhanced multiphoton ionization of H₂ ⁺ exposed to elliptically polarized VUV laser pulses is investigated. Differential cross sections for nuclei and electron are obtained using numerical solutions of the time-dependent Schrödinger equation. In this work in progress, we explore the dependence of the dissociative ionization observables with the polarization of the light.

Real-space grids and the Octopus code as tools for the development of new simulation approaches for electronic systems

Real-space grids are a powerful alternative for the simulation of electronic systems. One of the main advantages of the approach is the flexibility and simplicity of working directly in real space where the different fields are discretized on a grid, combined with competitive numerical performance and great potential for parallelization. These properties constitute a great advantage at the time of implementing and testing new physical models. Based on our experience with the Octopus code, in this article we discuss how the real-space approach has allowed for the recent development of new ideas for the simulation of electronic systems. Among these applications are approaches to calculate response properties, modeling of photoemission, optimal control of quantum systems, simulation of plasmonic systems, and the exact solution of the Schrödinger equation for low-dimensionality systems.

Cátedras extraordinarias. Semestre 2009-1

Folleto y programa descriptivo de las Cátedras Extraordinarias . Semestre 2009-1

Chiapas a través de los viajeros del siglo XVII: aspectos narrativos e historia descriptiva en Thomas Gage y Antonio Vázquez de Espinosa

Chiapas representó en el siglo XVII una región donde confluían los mitos, temores y fascinaciones de colonos y europeos. Al ser visitada por Thomas Gage en su travesía hacia Guatemala, es descrita en su Nuevo reconocimiento de las Indias Occidentales de modo muy distinto cuando el narrador, como es este caso, registra sus vivencias personales e, incluso, pasionales. Sólo la historiografía moderna podría explicarnos particulares pasajes en que el viajero es abordado súbitamente por una realidad que pasa desapercibida a otros viajeros con un programa muy claro de supervisión y registro de datos, como es el caso de Antonio Vázquez de Espinosa en su Descripción de la Nueva España. Si el historiógrafo describe puntualmente flora, fauna y geografía, el narrador huele, paladea y recorre con nosotros el laberinto de la tierra chiapaneca. El paisaje a través de la persona, con todos los cabos sueltos y apariciones inexplicables para quien se interna en lo desconocido, cobran, a la luz de investigaciones recientes acerca del contexto sociohistórico de Chiapas, un sentido cabal que no sólo nos ilustra, sino que nos interna y se nos interna.

Cátedras extraordinarias. Semestre 2009-2

Folleto y programa descriptivo de las Cátedras Extraordinarias . Semestre 2009-2

The PREDICTS database: a global database of how local terrestrial biodiversity responds to human impacts

Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species’ threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project – and avert – future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups – including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems – www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015.

Do people have insight into their face recognition abilities?

Diagnosis of developmental or congenital prosopagnosia (CP) involves self-report of everyday face recognition difficulties, which are corroborated with poor performance on behavioural tests. This approach requires accurate self-evaluation. We examine the extent to which typical adults have insight into their face recognition abilities across four studies involving nearly 300 participants. The studies used five tests of face recognition ability: two that tap into the ability to learn and recognise previously unfamiliar faces (the Cambridge Face Memory Test, CFMT, Duchaine & Nakayama, 2006 and a newly devised test based on the CFMT but where the study phases involve watching short movies rather than viewing static faces – the CFMT-Films) and three that tap face matching (Benton Facial Recognition Test, BFRT, Benton, Sivan, Hamsher, Varney, & Spreen, 1983; and two recently devised sequential face matching tests). Self-reported ability was measured with the 15-item Kennerknecht et al. (2008) questionnaire; two single-item questions assessing face recognition ability; and a new 77-item meta-cognition questionnaire). Overall, we find that adults with typical face recognition abilities have only modest insight into their ability to recognise faces on behavioural tests. In a fifth study, we assess self-reported face recognition ability in people with CP and find that some people who expect to perform poorly on behavioural tests of face recognition do indeed perform poorly. However, it is not yet clear whether individuals within this group of poor performers have greater levels of insight (i.e., into their degree of impairment) than those with more typical levels of performance.

Engagement no trabalho: a perspetiva do modelo demandas-recursos laborais

Cada vez mais as organizações encetam a dar valor ao funcionamento ótimo do indivíduo, uma vez que acarreta vantagens, tanto para o indivíduo, como para a própria organização. Partindo deste pressuposto, surge o engagement como o conceito em estudo na presente investigação. O objetivo desta investigação, a partir do modelo demandas-recursos laborais (Job Demand-Resources), é analisar as relações entre o empowerment psicológico e o engagement no trabalho, bem como o seu impacto sobre a satisfação no trabalho e no bem-estar dos trabalhadores. Participaram 306 sujeitos empregados de ambos os géneros, com idades compreendidas entre os 18 e 72 anos (M = 35.59, DP = 10.66), através de um questionário online. Os resultados indicam que o empowerment psicológico prediz significativamente o engagement, e o engagement prediz positivamente a satisfação profissional e o bemestar positivo no trabalho. Os resultados demonstram ainda, através da realização de uma path analysis que o engagement medeia a relação entre o empowerment psicológico e a satisfação profissional e o bem-estar positivo no trabalho. Constata-se assim a importância do engagement para a melhoria de qualidade de vida no trabalho. Futuras investigações deverão analisar profundamente as relações entre estas variáveis, com diferentes amostras e instituições.