State-dependent threshold STAR models

In this paper we consider extensions of smooth transition autoregressive (STAR) models to situations where the threshold is a time-varying function of variables that affect the separation of regimes of the time series under consideration. Our specification is motivated by the observation that unusually high/low values for an economic variable may sometimes be best thought of in relative terms. State-dependent logistic STAR and contemporaneous-threshold STAR models are introduced and discussed. These models are also used to investigate the dynamics of U.S. short-term interest rates, where the threshold is allowed to be a function of past output growth and inflation.

The Coordinated Radio and Infrared Survey for High-Mass Star Formation (The CORNISH Survey). I. Survey Design

We describe the motivation, design, and implementation of the CORNISH survey, an arcsecondresolution radio continuum survey of the inner galactic plane at 5 GHz using the Very Large Array (VLA). It is a blind survey coordinated with the northern SpitzerGLIMPSE I region covering 10° star formation. A sensitivity around 2 mJy will allow the automatic distinction between radio-loud and radio-quiet midIR sources found in the Spitzersurveys. This survey has many legacy applications beyond star formation, including evolved stars, active stars and binaries, and extragalactic sources. The CORNISH survey for compact ionized sources complements other Galactic plane surveys that target diffuse and nonthermal sources, as well as atomic and molecular phases to build up a complete picture of the interstellar medium in the Galaxy.

Isospin-rich nuclei in neutron star matter

Stability of nuclei beyond the drip lines in the presence of an enveloping gas of nucleons and electrons, as prevailing in the inner crust of a neutron star, is studied in the temperature-dependent Thomas-Fermi framework. A limiting asymmetry in the isospin space beyond which nuclei cannot exist emerges from the calculations. The ambient conditions such as temperature, baryon density, and neutrino concentration under which these exotic nuclear systems can be formed are studied in some detail.

Brittle to ductile transition in a fiber bundle with strong heterogeneity

We analyze the failure process of a two-component system with widely different fracture strength in the framework of a fiber bundle model with localized load sharing. A fraction 0≤α≤1 of the bundle is strong and it is represented by unbreakable fibers, while fibers of the weak component have randomly distributed failure strength. Computer simulations revealed that there exists a critical composition αc which separates two qualitatively different behaviors: Below the critical point, the failure of the bundle is brittle, characterized by an abrupt damage growth within the breakable part of the system. Above αc, however, the macroscopic response becomes ductile, providing stability during the entire breaking process. The transition occurs at an astonishingly low fraction of strong fibers which can have importance for applications. We show that in the ductile phase, the size distribution of breaking bursts has a power law functional form with an exponent μ=2 followed by an exponential cutoff. In the brittle phase, the power law also prevails but with a higher exponent μ=92. The transition between the two phases shows analogies to continuous phase transitions. Analyzing the microstructure of the damage, it was found that at the beginning of the fracture process cracks nucleate randomly, while later on growth and coalescence of cracks dominate, which give rise to power law distributed crack sizes.

A Be-type star with a black-hole companion

Stellar-mass black holes have all been discovered through X-ray emission, which arises from the accretion of gas from their binary companions (this gas is either stripped from low-mass stars or supplied as winds from massive ones). Binary evolution models also predict the existence of black holes accreting from the equatorial envelope of rapidly spinning Be-type stars (stars of the Be type are hot blue irregular variables showing characteristic spectral emission lines of hydrogen). Of the ~80 Be X-ray binaries known in the Galaxy, however, only pulsating neutron stars have been found as companions. A black hole was formally allowed as a solution for the companion to the Be star MWC 656 (also known as HD 215227), although that was based on a single radial velocity curve of the Be star, a mistaken spectral classification and rough estimates of the inclination angle. Here we report observations of an accretion disk line mirroring the orbit of the Be star. This, together with an improved radial velocity curve of the Be star through fitting sharp Fe II profiles from the equatorial disk, and a refined Be classification (to that of a B1.5-B2 III star), reveals a black hole of 3.8 to 6.9 solar masses orbiting MWC 656, the candidate counterpart of the gamma-ray source AGL J2241+4454. The black hole is X-ray quiescent and fed by a radiatively inefficient accretion flow giving a luminosity less than 1.6 x 10-7 times the Eddington luminosity. This implies that Be binaries with black-hole companions are difficult to detect by conventional X-ray surveys.

The star forming region Monoceros R2 as a gamma-ray source

After the release of the gamma-ray source catalog produced by the Fermi satellite during its first two years of operation, a significant fraction of sources still remain unassociated at lower energies. In addition to well-known high-energy emitters (pulsars, blazars, supernova remnants, etc.), theoretical expectations predict new classes of gamma-ray sources. In particular, gamma-ray emission could be associated with some of the early phases of stellar evolution, but this interesting possibility is still poorly understood. Aims: The aim of this paper is to assess the possibility of the Fermi gamma-ray source 2FGL J0607.5-0618c being associated with the massive star forming region Monoceros R2. Methods: A multi-wavelength analysis of the Monoceros R2 region is carried out using archival data at radio, infrared, X-ray, and gamma-ray wavelengths. The resulting observational properties are used to estimate the physical parameters needed to test the different physical scenarios. Results: We confirm the 2FGL J0607.5-0618c detection with improved confidence over the Fermi two-year catalog. We find that a combined effect of the multiple young stellar objects in Monoceros R2 is a viable picture for the nature of the source.

The Coordinated Radio and Infrared Survey for High-mass Star Formation. II. Source Catalog

The CORNISH project is the highest resolution radio continuum survey of the Galactic plane to date. It is the 5 GHz radio continuum part of a series of multi-wavelength surveys that focus on the northern GLIMPSE region (10° < l < 65°), observed by the Spitzer satellite in the mid-infrared. Observations with the Very Large Array in B and BnA configurations have yielded a 1.''5 resolution Stokes I map with a root mean square noise level better than 0.4 mJy beam 1. Here we describe the data-processing methods and data characteristics, and present a new, uniform catalog of compact radio emission. This includes an implementation of automatic deconvolution that provides much more reliable imaging than standard CLEANing. A rigorous investigation of the noise characteristics and reliability of source detection has been carried out. We show that the survey is optimized to detect emission on size scales up to 14'' and for unresolved sources the catalog is more than 90% complete at a flux density of 3.9 mJy. We have detected 3062 sources above a 7σ detection limit and present their ensemble properties. The catalog is highly reliable away from regions containing poorly sampled extended emission, which comprise less than 2% of the survey area. Imaging problems have been mitigated by down-weighting the shortest spacings and potential artifacts flagged via a rigorous manual inspection with reference to the Spitzer infrared data. We present images of the most common source types found: H II regions, planetary nebulae, and radio galaxies. The CORNISH data and catalog are available online at http://cornish.leeds.ac.uk.

Analog Modelling of N-S anticlines of the External Sierras (Jaca basin, Southern Pyrenees)

Report for the scientific sojourn carried out at the Uppsala Universitet, Sweden, from April to July the 2007. Two series of analogue models are used to explore ductile-frictional contrasts of the basal décollement in the development of oblique and transverse structures simultaneously to thin-skinned shortening. These models simulate the evolution of the Central External Sierras (Southern Pyrenees, Spain), which constitute the frontal emerging part of the southernmost Pyrenean thrust sheet. They are characterized by the presence of transverse N-S to NW-SE anticlines, which are perpendicular to the Pyrenean structural trend and developed in the hangingwall of the Santo Domingo thrust system, detaching on an unevenly distributed Triassic materials (evaporitic-dolomitic interfingerings). Model setup performs a décollement made by three patches of silicone neighbouring pure brittle sand. Model series A test the thickness ratio between overburden and décollement. Model series B test the width of frictional detachment areas. Model results show how deformation reaches further in areas detached on ductile layer whereas frictional décollement areas assimilate the strain by means of an additional uplift. This replicates the structural style of Central External Sierras: higher structural relief of N-S anticlines with regard to orogen-parallel structures, absence of a representative ductile décollement in the core, tilting towards the orogen and foreland-side closure not thrusted by the frontal emerging South-Pyrenean thrust.

Amor i literatura: dos conceptes per a la creació d'una novel·la

Treball de recerca realitzat per una alumna d'ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit cientí­fic del Jovent l'any 2009. L'amor, l'etern tema en el món literari és el protagonista de la temàtica en què se centra el projecte però, des de les primeres mostres literàries fins l'actualitat són infinites les creacions aparegudes. El treball s'ha centrat en algunes que són una digna representació de l'amor literari en cada època i en diverses parts de la literatura universal. Fins aquí un plantejament que no s'alunya de cap model realitzat dins de la temàtica de la literatura comparada. Però per solucionar la manca d'un fil conductor es va crear una novel·la que és la que guia aquest treball. Així es mostra el que una persona pot extreure llegint diverses obres d'amor literari, i no només sobre teories generals, sinó també d'opinions i pròpies emocions que provoca l'experiència de lectura. De la mà d en Marco, un jove veronès, i la seva vella amiga, la bibliotecària Sophie, es guia al lector a través d'un viatge que sorgeix de les primeres mostres d'amor escrit i arriba fins als nostres dies.

Behavior study of pipes after forming, coating and bending

A study of the main types of coatings and its processes that modern industry commonly apply to prevent to the corrosion due to the environmental effects to energetic market pipelines have been done. Extracting main time and temperature range values, coating heat treatment recreation have been applied to x65 pipelines steel grade samples obtained from a pipe which was formed using UOE forming process. Experimental tensile tests and Charpy V‐Notch Impact test have been carried out for a deeply knowledge of the influence on the steel once this recreations are applied. The Yield Strength and toughness have been improved despite lower values in rupture strain and ductile‐brittle temperature transition have been obtained. Finite Element Method have been applied to simulate the entirely pipe cold bending process to predict the mechanical properties and behaviour of the pipe made from x65 steel grade under different conditions.

Ecoetiqueta de serveis i aprofitament dels recursos hídrics i energètics als establiments hotelers de Sitges

Aquest projecte té com a objectiu l’estudi de l’estat ambiental dels hotels del municipi de Sitges i l’estudi d’aprofitament dels recursos hídrics i energètics característics d’aquesta zona del Mediterrani per hotels de 4 i 5 estrelles. Sitges és un municipi que al període estival dobla la població, i que amb una superfície de 43,85 Km2 conta amb 35 hotels i apart pensions, hostals i càmpings, per tant, el turisme és l’activitat més important a Sitges. Per desenvolupar aquest projecte s’ha realitzat una enquesta senzilla sobre qualitat ambiental per conèixer el comportament ambiental dels diferents hotels. En aquest estudi han participat 15 dels 35 hotels del municipi, ja que el 49% d’aquests romanen tancats des d’Octubre fins a Març i dels 18 hotels restants 15 han accedit a formar part d’aquest estudi. A través d’una prova pilot s’ha avaluat la implantació del Distintiu de Garantia de Qualitat Ambiental a l’hotel Antemare i a l’hotel Sunway Playa Golf, aquests dos hotels pertanyen a la categoria de quatre estrelles, categoria que reuneix més nombre d’hotels i el tant per cent d’ocupació és major en comparació amb les altres categories. El DGQA és una ecoetiqueta de serveis que atorga la Generalitat de Catalunya a partir de la revisió de l’establiment per mitjà d’un tècnic autoritzat. S’ha analitzat l’aprofitament dels recursos local com, les aigües pluvials i la radiació solar en els hotels de 4 i 5 estrelles per obtenir l’autosuficiència individual dels 9 hotels objecte d’estudi. Els resultats obtinguts en aquest estudi reflecteixen la possibilitat de millorar l’estat ambiental dels establiments hotelers, duent a terme alguns criteris bàsics com, la recollida selectiva i una major implantació d’energies renovables, així com també la utilització d’aquestes per assolir un cert nivell d’autosuficiència energètica i hídrica. La prova pilot mostra que els dos hotels estudiats estan molt a prop d’aconseguir el DGQA, els vectors on s’haurien de fer millores són, informació ambiental, energia, aigua i residus.

Emissió ràdio a baixa freqüència en fenòmens eruptius i en fonts esteses de raigs gamma d'alta i molt alta energia

La tasca investigadora presentada en aquesta memòria s'ha centrat en les fonts galàctiques de raigs gamma de molt alta energia LS I +61 303, HESS J1708-410 i HESS J1858+020. La primera és una binària de raigs gamma molt estudiada, formada per una estrella massiva i un objecte compacte. S'ha proposat un escenari on l'objecte compacte seria un púlsar jove, i la interacció del seu vent amb el vent de l'estrella generaria els raigs gamma. De totes formes, no s'ha detectat polsos procedents d'aquest putatiu púlsar. L'investigador va realitzar observacions en fase a 1280 MHz amb el radiotelescopi GMRT, sense trobar-hi polsos, cosa que implica un estricte límit superior de 0,38 mJy a la densitat mitjana de flux polsat en un putatiu púlsar amb un període major que 2 mil•lisegons en el sistema binari LS I +61 303. Per altra banda, HESS J1708-410 i HESS J1858+020 són dues fonts esteses de raigs gamma de molt alta energia de les quals no es coneix cap contrapart a d'altres longituds d'ona. L'investigador les va observar amb el GMRT, quatre vegades HESS J1708-410 (dues a 610 MHz i dues a 1400 MHz) i dues vegades HESS J1858+020 (una a cada freqüència). En les imatges realitzades amb aquestes dades no hi ha emissió estesa coincident amb les regions d'emissió de raigs gamma. HESS J1858+020 se solapa parcialment amb una font estesa que podria ser un SNR. De confirmar-se la falta de contrapartida ràdio de HESS J1708-410, estaríem parlant d'un accelerador hadrònic extraordinàriament eficient, d'una classe desconeguda fins ara.

Predicting random level and seasonality of hotel prices. A structural equation growth curve approach

This article examines the effect on price of different characteristics of holiday hotels in the sun-and-beach segment, under the hedonic function perspective. Monthly prices of the majority of hotels in the Spanish continental Mediterranean coast are gathered from May to October 1999 from the tour operator catalogues. Hedonic functions are specified as random-effect models and parametrized as structural equation models with two latent variables, a random peak season price and a random width of seasonal fluctuations. Characteristics of the hotel and the region where they are located are used as predictors of both latent variables. Besides hotel category, region, distance to the beach, availability of parking place and room equipment have an effect on peak price and also on seasonality. 3- star hotels have the highest seasonality and hotels located in the southern regions the lowest, which could be explained by a warmer climate in autumn

Desarrollo de una metodología fluídica para el estudio del confort climático en el habitáculo de un vehículo

El objetivo primordial de este proyecto es establecer y documentar las condiciones deconfort climático y desarrollar un modelo dummy capaz de interpretar la sensación térmica teniendo en cuenta factores internos como; temperatura, velocidad, y dirección del aire.La simulación numérica se realizará con el código Star CCM + de CD- ADAPCO