Gravitational wave production from the decay of the Standard Model Higgs field after inflation

During or towards the end of inflation, the Standard Model (SM) Higgs forms a condensate with a large amplitude. Following inflation, the condensate oscillates, decaying non-perturbatively into the rest of the SM species. The resulting out-of-equilibrium dynamics converts a fraction of the energy available into gravitational waves (GW). We study this process using classical lattice simulations in an expanding box, following the energetically dominant electroweak gauge bosons $W^\pm$ and $Z$. We characterize the GW spectrum as a function of the running couplings, Higgs initial amplitude, and post-inflationary expansion rate. As long as the SM is decoupled from the inflationary sector, the generation of this background is universally expected, independently of the nature of inflation. Our study demonstrates the efficiency of GW emission by gauge fields undergoing parametric resonance. The initial energy of the Higgs condensate represents however, only a tiny fraction of the inflationary energy. Consequently, the resulting background is very suppressed, with an amplitude $h^2 \Omega_{\rm GW}^{(o)} \lesssim 10^{-29}$ today. The amplitude can be boosted to $h^2 \Omega_{\rm GW}^{(o)} \lesssim 10^{-16}$, if following inflation the universe undergoes a kination-domination stage; however the background is shifted in this case to high frequencies $f_p \lesssim 10^{11} {\rm Hz}$. In all cases the signal is out of the range of current or planned GW detectors. This background will therefore remain, most likely, as a curiosity of the SM.Comment: 16 pages, 6 figures. Minor changes to match version published in PR

Curvature and velocity of methane-air Bunsen flame tips

PIV and photographic recording are used to measure the velocity of the fresh gas and the shape of the reaction layer in a region around the tip of a methane- air Bunsen flame attached to a cylindrical burner. The results compare well with numerical simulations carried out with an infinite activation energy reaction model. The experimental and numerical results confirm that the well-known linear relation between flame velocity and flame stretch derived from asymptotic theory for weakly curved and strained flames is valid for small and moderate values of the flame stretch if the modified definition of stretch introduced by Echekki and Mungal (Proc Combust Inst 23:455–461,1990) and Poinsot et al. (Combust Sci Technol 81:45–73,1992) is used. However, the relation between flame velocity and modified stretch ceases to be linear and approaches a square root law for large values of the stretch, when the curvature of the flame tip becomes large compared to the inverse of the thickness of a planar flam

Estableciendo diálogos entre diferentes marcos teóricos: de los procesos narrativos a la teoría antropológica de lo didáctico

El punto de partida de este artículo es el fenómeno de la co-existencia de diferentes marcos teóricos en didáctica de las matemáticas. Proponemos reformular este fenómeno en términos de un problema científico: el problema del establecimiento de diálogos entre praxeologías de investigación. Iniciamos un diálogo entre dos praxeología de investigación partiendo de una secuencia de clase de una profesora inglesa. El problema de investigación inicial, comprender la acción didáctica de la profesora, fue formulado y abordado, desde la tradición anglosajona, usando el marco de los procesos narrativos. Exploramos aquí los mismos hechos empíricos desde la Teoría Antropológica de lo Didáctico, mostrando que cada praxeología de investigación construye sus propios problemas de investigación y ofreciendo resultados nuevos y complementarios

An annotated checklist of bryophytes of Europe, Macaronesia and Cyprus

Artículo escrito por un elevado número de autores, sólo se referencian el que aparece en primer lugar, los autores pertenecientes a la UAM y el nombre del grupo de colaboración, si lo hubiereIntroduction.Following on from work on the European bryophyte Red List, thetaxonomically and nomenclaturally updated spreadsheets used for that project have beenexpanded into a new checklist for the bryophytes of Europe.Methods.A steering group of ten European bryologists was convened, and over the courseof a year, the spreadsheets were compared with previous European checklists, and allchanges noted. Recent literature was searched extensively. A taxonomic system wasagreed, and the advice and expertise ofmany European bryologists sought.Key results.A new European checklist of bryophytes, comprising hornworts, liverworts andmosses, is presented. Fifteen new combinations are proposed.Conclusions.This checklist provides a snapshot of the current European bryophyteflorain 2019. It will already be out-of-date on publication, and further research, particularlymolecular work, can be expected to result in many more changes over the next few yearsThis project would not have been possible, or at leastwould have been much more difficult, without the initialRed List project, which wasfinanced chiefly through an ECLIFE projec

Productos de alfarería de Cerro Macareno, Sevilla : naturaleza y procedencia de las ánforas y otros objetos cerámicos. Siglos VIII al III a. J.C.

Son muchos los métodos empleados para el estudio de las arcillas y de los productos cerámicos, contribuyendo de distinta manera, aunque complementaria, en el conocimiento de la composición, procedencia de los materiales, tecnología empleada en su elaboración y en general en todos aquellos procesos que se pudieron seguir en la tibricación del objeto cerámico. Estos métodos pueden ser, bien destructivos, aunque utilizando cantidades muy pequeñas de muestra, o bien no destructivos, cada vez más empleados en la investigación moderna. En el estudio de los materiales cerámicos, bien sea el soporte, o bien sea la pintura que ha servido para decorarlo, se emplea el análisisq\límico tradicional cualitativo y cuantitativo. Para este último se emplea cada \leimás la técnica de la absorción atómica. Asimismo, se emplean los siguientes métodos de análisis por vía física: La espectroscopía de emisión en el ultravioleta, que permite obtener un espectro de emisión en el que la parte más frecuentemente utilizada se sitúa entre 200 y 400 nm (ultravioleta). La espectrometría de fluorescencia de rayos X es una técnica desde hace tiempo utilizada. El método tiene poca sensibilidad para elementos tales como el cobre, níquel, cinc o hierro, a causa del «ruido de fondo» que el mismo aparato emite. La microfluorescencia permite operar directamente sobre una capa de pintura y su análisis no es destructivo. La microsonda electrónica es una aplicación de los principios y de la técnica de la espectrografía de emisión de rayos X. Su poder separador es infinitamente superior al del mejor instrumento óptico. La activación por neutrones, que precisa de una fuente generadora de estas radiaciones (pila atómica), es, por tanto, de muy difícil empleo. En España se utiliza la pila atómica de la Junta de Energía Nuclear. Este análisis permite determinar los elementos mayores, menores y trazas existentes en los objetos cerámicos y en los pigmentos. Es de un gran interés para conocer la procedencia de los materiales empleados, detectando el posible o posibles yacimientos de las arcillas utilizadas. La difracción de rayos X determina la estructura cristalina de los elementos y compuestos químicos ya sean orgánicos o inorgánicos, si bien la técnica no es válida para los compuestos amorfos. Para el estudio de aquellos materiales en los que la pintura se encuentre unida al soporte mediante lacas, gomas o barnices se emplean métodos de absorción en el infrarrojo, así como la cromatografía en fase gaseosa. Los métodos seguidos que se enumeran en el siguiente apartado nos han permitido identificar la procedencia y naturaleza de las arcillas utilizadas en los objetos cerámicos objeto de este estudio.Peer reviewe

Materias primas y datos tecnológicos de piezas cerámicas antiguas del yacimiento arqueológico de Cerro Macareno (Sevilla)

14 páginas, 5 figuras, 7 tablas, 7 referencias.[EN]: A study of twenty eight fragments of amphoras from the archaeological bed of Cerro Macareno (Sevilla) has been done by chemical, physicochemical, X-ray diffraction and thermal methods, in order to establish the nature and provenance of the raw materials and the technological aspects of their fabrication. All the data lead to the conclusion that four of the pieces were probably imported from the Palestine-Phoenicie; the rest were made out of raw materials from the surrounding areas of Cerro Macareno. Most of the pieces were fired below 700°C, only four of them at about 700-750°C, and the other seven, probably from 800-850°C.[ES]: Se estudian la composición química y mineralógica, contenido en determinados elementos escasos, materias primas y temperaturas probables de cocción empleadas en la fabricación de un conjunto de 25 fragmentos de ánforas del yacimiento arqueológico de Cerro Macareno (Sevilla). Los métodos empleados fueron análisis químico, difracción de rayos-X, A.T.D., análisis por activación neutrónica y pruebas de cocción intermitente por calentamiento de cien en cien grados, desde 400° a 1.100° C seguido en cada caso de estudios por difracción de rayos-X y de observación de los cambios de color y aspecto de los cortes de las piezas. De todo ello se concluye que cuatro de las piezas estudiadas son de origen importado (Palesti-na-Fenicia), estando fabricadas las restantes con materiales procedentes de los aluviones del Guadalquivir, en las inmediaciones del Cerro Macareno. Del total de las piezas, 17 se cocieron probablemente a temperaturas inferiores a 700°C, cuatro a 700-750° C y siete a 800-850°C.Peer reviewe

Resistance to eyespot (Pseudocercosporella herpotricoides) and distribution of biochemical markers in hexaploid lines derived from double cross (Triticum turgidum x Aegilops ventricosa) x T. aestivum

There are not good intraspecific sources of resistance to the eyespot disea se of wheat, aaused by Cercosporella herpotrichoides Fvon . The -ínterspecifia transfer of genes for resistanoe from Aegitops ventricosa into hexaploid wheat has been only partially achieved, because the degree of resistanoe attained is not as high as that of the donor. We report here on the transfer of resistanoe in a double oross (Triticum turgidum var. rubroatrwv H-1-1 x Ae.ventricosa AP-D x T.aestivum cv. Almatense H-10-15. The high level of resistanoe in a high proportion of the lines strongly suggests a simple genetic control for this oharacter (possibly by one major gene). The gene(s) responsible for resistanoe in the selected lines must be associa ted with the D genome of Aegilops ventricosa on the basis of a detailed study of the distribution of biochemioal markers in the H-93 lines. These results do not exelude that genes with similar effeets might be looated in the M° genome

Measurement of the burning velocity of strongly curved methane-air flames

An experimental and numerical study has been carried out of the region around the tip of a methane-air premixed flame attached to a circular laminar jet burner. On the experimental side, photographic records and PIV have been used to measure the shape of the reaction layer and the velocity of the gas around the tip of the flame. The numerical part of the study includes simulations of stationary axisymmetric flames with infinitely high activation energy reactions. The experimental and numerical results compare well with each other and allow to determine the curvature of the reaction layer at the tip and the velocity and strain rate of the fresh gas flow along the axis of the burner. These data, together with the planar flame velocity determined by extrapolating the velocity of the flame at the tip to the limit of zero stretch, are used to assess the well-known linear flame-velocity/flame-stretch relationship originally proposed by Markstein and later derived in the asymptotic limit of weakly curved and strained flames [1, 2], as well as the phenomenological modification proposed more recently by Mungal and coworker

Curvature and burning velocity of Bunsen Flame tips.

The burning velocity of a premixed flame propagating in a given flammable mixture is known to depend on the difference between the curvature of the flame and the so-called curvature of the flow, which is the strain rate of the flow of fresh gas along the normal to the flame divided by the burning velocity of the planar flame. The difference between the local burning velocity and the burning velocity of a planar flame in a gas at rest is proportional to the difference of the flame and flow curvatures. The proportionality factor is the product of the burning velocity of the planar flame and the Markstein length, which is an intrinsic property of the flame that characterizes its dynamics. The Markstein length can be determined experimentally by simultaneously measuring the curvature of the flame and the strain rate of the flow. To achieve this goal, we have set up a laminar jet burner and used two PIV systems to measure the gas flow velocity in two perpendicular planes normal to the flame. Each PIV system is composed by two Q-switched Nd: YAG pulse lasers (New Wave, maximum 120 mJ/pulse at 532 nm wavelength), a double-shuttered cross-correlation camera (PCO, 1392 × 1040 pixels) and a pulse generator (ILA GmbH) to synchronize all the components as well as the two PIV systems. Oil droplets are used for tracking the flow and the flame. They are formed by condensation after oil evaporation in a seeding chamber placed in the air line. Seeded air and fuel gas (CO,H2, CH4) are mixed in a settling chamber upstream of the burner and burned in a stationary Bunsen flame. The oil droplets evaporate in the flame preheating region, thereby allowing a dual tomography of the front

Local burning velocity in a Bunsen jet flame

A PIV-based system has been set-up for the simultaneous measurement of the local burning velocity of premixed flames and the flame stretch due to the flame front curvature and the incoming flow strain rate. For moderately short jet flames, these measurements allow an indirect determination of the Markstein length, according to Clavin and Joulin (C–J) theory. For tall flames, the flame curvature becomes relatively large in a region around the tip where the C–J theory breaks down. However, our experiments confirm the appearance of a new linear relation between burning velocity and curvature at the flame tip. This relation defines a new proportionality factor which is probably associated to the evolution from rounded tips to slender tips when the jet velocity is increased