Deformation of canonical morphisms and the moduli of surfaces of general type

In this article we study the deformation of finite maps and show how to use this deformation theory to construct varieties with given invariants in a projective space. Among other things, we prove a criterion that determines when a finite map can be deformed to a one--to--one map. We use this criterion to construct new simple canonical surfaces with different $c_1^2$ and $\chi$. Our general results enable us to describe some new components of the moduli of surfaces of general type. We also find infinitely many moduli spaces $\mathcal M_{(x',0,y)}$ having one component whose general point corresponds to a canonically embedded surface and another component whose general point corresponds to a surface whose canonical map is a degree 2 morphism.Comment: 32 pages. Final version with some simplifications and clarifications in the exposition. To appear in Invent. Math. (the final publication is available at springerlink.com

Ferromagnetism in defect-ridden oxides and related materials

The existence of high-temperature ferromagnetism in thin films and nanoparticles of oxides containing small quantities of magnetic dopants remains controversial. Some regard these materials as dilute magnetic semiconductors, while others think they are ferromagnetic only because the magnetic dopants form secondary ferromagnetic impurity phases such as cobalt metal or magnetite. There are also reports in d0 systems and other defective oxides that contain no magnetic ions. Here, we investigate TiO2 (rutile) containing 1 - 5% of iron cations and find that the room-temperature ferromagnetism of films prepared by pulsed-laser deposition is not due to magnetic ordering of the iron. The films are neither dilute magnetic semiconductors nor hosts to an iron-based ferromagnetic impurity phase. A new model is developed for defect-related ferromagnetism which involves a spin-split defect band populated by charge transfer from a proximate charge reservoir in the present case a mixture Fe2+ and Fe3+ ions in the oxide lattice. The phase diagram for the model shows how inhomogeneous Stoner ferromagnetism depends on the total number of electrons Ntot, the Stoner exchange integral I and the defect bandwidth W; the band occupancy is governed by the d-d Coulomb interaction U. There are regions of ferromagnetic metal, half-metal and insulator as well as nonmagnetic metal and insulator. A characteristic feature of the high-temperature Stoner magnetism is an an anhysteretic magnetization curve which is practically temperature independent below room temperature. This is related to a wandering ferromagnetic axis which is determined by local dipole fields. The magnetization is limited by the defect concentration, not by the 3d doping. Only 1-2 % of the volume of the films is magnetically ordered.Comment: 22 pages, 6 figure

Selfsimilar Domain Growth, Localized Structures and Labyrinthine Patterns in Vectorial Kerr Resonators

We study domain growth in a nonlinear optical system useful to explore different scenarios that might occur in systems which do not relax to thermodynamic equilibrium. Domains correspond to equivalent states of different circular polarization of light. We describe three dynamical regimes: a coarsening regime in which dynamical scaling holds with a growth law dictated by curvature effects, a regime in which localized structures form, and a regime in which polarization domain walls are modulationally unstable and the system freezes in a labyrinthine pattern.Comment: 13 pages, 6 figure

Towards a Precision Cosmology from Starburst Galaxies at z>2

This work investigates the use of a well-known empirical correlation between the velocity dispersion, metallicity, and luminosity in H beta of nearby HII galaxies to measure the distances to HII-like starburst galaxies at high redshifts. This correlation is applied to a sample of 15 starburst galaxies with redshifts between z=2.17 and z=3.39 to constrain Omega_m, using data available from the literature. A best-fit value of Omega_m = 0.21 +0.30 -0.12 in a Lambda-dominated universe and of Omega_m = 0.11 +0.37 -0.19 in an open universe is obtained. A detailed analysis of systematic errors, their causes, and their effects on the values derived for the distance moduli and Omega_m is carried out. A discussion of how future work will improve constraints on Omega_m by reducing the errors is also presented.Comment: 7 pages, 3 figures, accepted for publication in MNRA

CLIWOC multilingual meteorological dictionary

This dictionary is the first attempt to express the wealth of archaic logbook wind force terms in a form that is comprehensible to the modern-day reader. Oliver and Kington (1970) and Lamb (1982) have drawn attention to the importance of logbooks in climatic studies, and Lamb (1991) offered a conversion scale for early eighteenth century English wind force terms, but no studies have thus far pursued the matter to any greater depth. This text attempts to make good this deficiency, and is derived from the research undertaken by the CLIWOC project1 in which British, Dutch, French and Spanish naval and merchant logbooks from the period 1750 to 1850 were used to derive a global database of climatic information. At an early stage in the project it was apparent that many of the logbook weather terms, whilst conforming to a conventional vocabulary, possessed meanings that were unclear to twenty-first century readers or had changed over time. This was particularly the case for the important element of wind force; but no special plea is entered for the evolution in nautical vocabulary, which often reflected more wide-ranging changes in the respective native languages.The key objective was to translate the archaic vocabulary of the late eighteenth and early nineteenth century mariner into expressions directly comparable with the Beaufort Scale (see Appendix I). Only then could the projects scientific programme be embarked upon. This dictionary is the result of the largest undertaking into logbook studies that has yet been carried out. Several thousand logbooks from British, Dutch, French and Spanish archives were examined, and the exercise offered a unique opportunity to explore the vocabulary of the one hundred year period beginning in 1750. The logbooks from which the raw data have been abstracted range widely across the North and South Atlantic and the Indian Oceans. Only the Pacific, largely in consequence of the paucity of regular naval activity in that area, is not well represented. The range of climates encountered in this otherwise wide geographic domain gives ample opportunity for the full range of the mariners nautical weather vocabulary to be assessed, from the calms of the Equatorial regions, through the gales of the mid-latitude systems to the fearsome storms of the tropical latitudes. The Trade Winds belts, the Doldrums, the unsettled mid-latitudes, even the icy wastes of the high latitudes, are all embraced in this study. It is not here intended to pass any judgements on the climatological record of the logbooks, and this text seeks only to provide a means of understanding archaic wind force terms and, other than to indicate those items that were not commonly used, no information is given on the frequency with which different terms appeared in the logbooks. Attention is, furthermore, confined to Dutch, English, French and Spanish because these once great imperial powers were the only nations able to support wide-ranging ocean-going fleets with their attendant collections of logbooks and documents over this long period of time. The work is offered to the wider academic community in the hope that they will prove to be of as much value as it has been to the CLIWOC team

The interception of a corner kick from the contraints-led perspective

El comportamiento motor surge de la continua interacción entre tres limitadores (organismo, entorno y tarea), que nunca actúan de forma aislada. Este artículo estudia su efecto en el rendimiento, comportamiento motor y comportamiento visual de porteros de fútbol durante el lanzamiento de córner. 31 participantes, divididos en tres grupos en función del nivel de juego, intentaron atrapar el balón procedente del lanzamiento de córner en dos situaciones (estática y dinámica), mientras que se registraron sus movimientos oculares. Entre los resultados se observa que los expertos tienen un rendimiento más estable, mientras que los otros grupos rinden peor en la situación más difícil; que los expertos realizan un inicio más tardío de la carrera hacia el balón y un patrón motor más rápido para atraparlo; y que la información contenida en los jugadores implicados no es relevante, ya que los porteros dedican valores cercanos al 0% del tiempo total a su fijaciónMotor behavior arises from the continuous interaction between three constraints (organism, environment and task), which never act in isolation. This paper studies the effect of the constraints on the performance, motor behavior and visual search behavior of soccer goalkeepers during the corner kick. 31 participants, divided into three groups depending on the level of play, tried to catch the ball out of a corner kick in two situations (static and dynamic), while their eye movements were recorded. Among the results it is observed that the experts have a more stable performance, while the other groups perform worse in the most difficult situation; that the experts make a later start of their run up towards the ball and a faster motor pattern to catch it; and that the that the information of the players involved is not relevant, goalkeepers dedicate values close to 0% of their visual total time to themLa presente investigación se llevó a cabo mientras el primer autor y la segunda autora disfrutaban de una beca FPU (Formación del Profesorado Universitario) otorgada por el Ministerio de Educación, Cultura y Deporte del Gobierno de España

The gaseous mediator, hydrogen sulphide, inhibits in vitro motor patterns in the human, rat and mouse colon and jejunum

Hydrogen sulphide (H2S) has been recently proposed as a transmitter in the brain and peripheral tissues. Its role in the gastrointestinal tract is still unknown despite some data which suggest an involvement mediating smooth muscle relaxation. The aim of this study was to investigate the effect of this gas on intestinal segments from mouse jejunum and colon, and muscular strips from the human and rat colon. In isolated segments of mouse colon and jejunum, bath applied sodium hydrogen sulphide (NaHS) (a H2S donor) caused a concentration-dependent inhibition of spontaneous motor complexes (MCs) (IC50 121 μmol L-1 in the colon and 150 μmol L-1 in the jejunum). This inhibitory effect of NaHS on MCs was (i) unaffected by tetrodotoxin (TTX), capsaicin, pyridoxal-phosphate- 6-azophenyl-2',4'-disulfonate and N-nitro-l-arginine suggesting a non-neural effect and (ii) significantly reduced by apamin 3 μmol L -1. NaHS concentration-dependently inhibited the spontaneous motility in strips from human colon (IC50 261 μmol L-1) and rat colon (IC50 31 μmol L-1). The inhibitory effect of NaHS on colonic strips was (i) unaffected by the neural blocker TTX (1 μmol L-1) with IC50 183 μmol L-1 for the human colon and of 26 μmol L-1 for the rat colon and (ii) significantly reduced by glybenclamide (10 μmol L-1), apamin (3 μmol L -1) and TEA (10 mmol L-1) with IC50 values of 2464, 1307 and 2421 μmol L-1 for human strips, and 80, 167 and 674 μmol L-1 for rat strips respectively. We conclude that H 2S strongly inhibits in vitro intestinal and colonic motor patterns. This effect appears to be critically dependent on K channels particularly apamin-sensitive SK channels and glybenclamide-sensitive K (ATP) channels. © 2008 The Authors

The importance of ship log data: reconstructing North Atlantic, European and Mediterranean sea level pressure fields back to 1750

Local to regional climate anomalies are to a large extent determined by the state of the atmospheric circulation. The knowledge of large-scale sea level pressure (SLP) variations in former times is therefore crucial when addressing past climate changes across Europe and the Mediterranean. However, currently available SLP reconstructions lack data from the ocean, particularly in the pre-1850 period. Here we present a new statistically-derived 5°×5° resolved gridded seasonal SLP dataset covering the eastern North Atlantic, Europe and the Mediterranean area (40°W-50°E; 20°N-70°N) back to 1750 using terrestrial instrumental pressure series and marine wind information from ship logbooks. For the period 1750-1850, the new SLP reconstruction provides a more accurate representation of the strength of the winter westerlies as well as the location and variability of the Azores High than currently available multiproxy pressure field reconstructions. These findings strongly support the potential of ship logbooks as an important source to determine past circulation variations especially for the pre-1850 period. This new dataset can be further used for dynamical studies relating large-scale atmospheric circulation to temperature and precipitation variability over the Mediterranean and Eurasia, for the comparison with outputs from GCMs as well as for detection and attribution studie