Global bifurcation for monotone fronts of elliptic equations

In this paper, we present two results on global continuation of monotone front-type solutions to elliptic PDEs posed on infinite cylinders. This is done under quite general assumptions, and in particular applies even to fully nonlinear equations as well as quasilinear problems with transmission boundary conditions. Our approach is rooted in the analytic global bifurcation theory of Dancer and Buffoni--Toland, but extending it to unbounded domains requires contending with new potential limiting behavior relating to loss of compactness. We obtain an exhaustive set of alternatives for the global behavior of the solution curve that is sharp, with each possibility having a direct analogue in the bifurcation theory of second-order ODEs. As a major application of the general theory, we construct global families of internal hydrodynamic bores. These are traveling front solutions of the full two-phase Euler equation in two dimensions. The fluids are confined to a channel that is bounded above and below by rigid walls, with incompressible and irrotational flow in each layer. Small-amplitude fronts for this system have been obtained by several authors. We give the first large-amplitude result in the form of continuous curves of elevation and depression bores. Following the elevation curve to its extreme, we find waves whose interfaces either overturn (develop a vertical tangent) or become exceptionally singular in that the flow in both layers degenerates at a single point on the boundary. For the curve of depression waves, we prove that either the interface overturns or it comes into contact with the upper wall.Comment: 60 pages, 6 figure

Pathologic use of video games and gotivation. Can the Gaming Motivation Scale (GAMS) predict depression and trait anxiety?

Videogaming is an increasingly prevalent activity among adolescents worldwide. The present study aimed at adapting the Gaming Motivation Scale (GAMS) to the Italian context, assessing its psychometric properties and verifying its sensitivity to predict depression and anxiety levels. From a sample of 1899 participants, a group of 388 adolescents who participated in the survey was divided into two subgroups of Heavy (HG, N = 188) and Light Gamers (LG, N = 200). A sub-sample of N = 172 adolescents also filled-in CESD and STAI to assess, respectively, depression and trait anxiety. Internal consistency and factorial structure of the Italian version of GAMS (GAMS-it) have been evaluated. Moreover, a latent regression structural equation model by predicting the CES-D and STAI scores with the GAMS-it factors has been carried out. GAMS-it has adequate validity and reliability levels, showing a very similar factorial structure to the original version. Therefore, this scale can be used to evaluate gaming motivation, which is useful for gaming motivation screening. Finally, it has been found that lower gaming motivation can be related to high level of depression and anxiety. The present findings provide a coherent picture, supporting the reliability and validity of the GAMS-it, that appears potentially useful in predicting anxiety and depression levels in a population of adolescent

Is there a rural-urban divide? Location and Productivity of UK manufacturing

We compute the productivity gaps in manufacturing industries by urban, rural less sparse and rural sparse locations in the UK. This is done by using firm-specific total factor productivities, which are estimated by a semi-parametric algorithm within 4-digit manufacturing industries using FAME data over the period 1994-2001, by each location. We analyse the productivity differentials across locations by decomposing them into firm differences within the same industry and by differences that are explained by industry composition effects. Our analysis indicates that at the end of twentieth century a rural-urban divide in manufacturing productivity still remains but there is a tendency of convergence between rural and urban location categories. Even though industry productivity is different by location, industry composition effects are positively correlated with industry productivity by location suggesting that locations with high productivity are also characterised by industrial structures with higher productivity.Total factor productivity, structural estimation, rural-urban divides, UK manufacturing

ANALYSING THREE BASIC DECISIONS OF TOURISTS: GOING AWAY, GOING ABROAD AND GOING ON TOUR

This study analyses determinant factors in the taking of three basic decisions on the part of holidaymakers: going on holiday, foreign holidays and multi-destination holidays. We propose various research hypotheses relating to the impact on these decisions of various personal characteristics. The methodology used estimates various Binomial Logit models. The empirical application carried out in Spain on a sample of 3,781 individuals allows us to conclude that personal characteristics related to the chosen destination, personal restrictions and socio-demographic and psychographic characteristics are determinants of these decisions. This study analyses determinant factors in the taking of three basic decisions onthe part of holidaymakers: going on holiday, foreign holidays and multi-destinationholidays. We propose various research hypotheses relating to the impact on thesedecisions of various personal characteristics. The methodology used estimates variousBinomial Logit models. The empirical application carried out in Spain on a sample of3,781 individuals allows us to conclude that personal characteristics related to thechosen destination, personal restrictions and socio-demographic and psychographiccharacteristics are determinants of these decisions.Tourism Marketing, Choice Behaviour, Probabilistic Choice Models Marketing Turístico, Comportamiento de Elección, Modelos Probabilísticos de Elección.

On the sustainability of the Spanish public budget performance

In this paper, we address the issue of whether the current fiscal policy in Spain is sustainable. For this purpose we apply traditional empirical tests of fiscal sustainability proposed in the literature and, in addition, we introduce a deeper univariate analysis of the series involved. Our results show that a structural break seems to have taken place gradually in the Spanish budget performance, allowing to verifying the intertemporal borrowing constraint in a «strong sense», which means that no problems in marketing public debt are expected to arise if fiscal variables follow the pattern of the past in the future. Classification-JEL : E60, F41,: Sustainability, cointegration, structural breaks, intertemporal borrowing constraint.

How Skillful are the Multiannual Forecasts of Atlantic Hurricane Activity?

The recent emergence of near-term climate prediction, wherein climate models are initialized with the contemporaneous state of the Earth system and integrated up to 10 years into the future, has prompted the development of three different multiannual forecasting techniques of North Atlantic hurricane frequency. Descriptions of these three different approaches, as well as their respective skill, are available in the peer-reviewed literature, but because these various studies are sufficiently different in their details (e.g., period covered, metric used to compute the skill, measure of hurricane activity), it is nearly impossible to compare them. Using the latest decadal reforecasts currently available, we present a direct comparison of these three multiannual forecasting techniques with a combination of simple statistical models, with the hope of offering a perspective on the current state-of-the-art research in this field and the skill level currently reached by these forecasts. Using both deterministic and probabilistic approaches, we show that these forecast systems have a significant level of skill and can improve on simple alternatives, such as climatological and persistence forecasts.The first author would like to thank Isadora Jimenez for providing the necessary material for Fig. 2. The first author would like to acknowledge the financial support from the Ministerio de Economía, Industria y Competitividad (MINECO; Project CGL2014- 55764-R), the Risk Prediction Initiative at BIOS (Grant RPI2.0-2013-CARON), and the EU [Seventh Framework Programme (FP7); Grant Agreement GA603521]. We additionally acknowledge the World Climate Research Programme’s Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modeling groups for producing and making available their model output. For CMIP, the U.S. Department of Energy’s Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. LPC's contract is cofinanced by the MINECO under the Juan de la Cierva Incorporacion postdoctoral fellowship number IJCI-2015-23367. Finally, we thank the National Hurricane Center for making the HURDAT2 data available. All climate model data are available at https://esgf-index1.ceda.ac.uk/projects/esgf-ceda/.Peer ReviewedPostprint (published version

Is there a limit to agglomeration? Evidence from productivity of Dutch firms

Abstract We compute aggregate productivity of three categories of regions, classified by level of urbanization in the Netherlands, from firm-specific total factor productivity (TFP) measures. TFP measures are estimated by a semi-parametric algorithm, within 2-digit industries, covering agriculture, manufacturing, construction, trade and services, using AMADEUS data over the period 1997-2006. We analyse the productivity differentials across urbanization categories by decomposing them into industry productivity effect and industry composition effect. Our analysis indicates that there is non-linear, inverted U-shape effect of agglomeration on productivity growth but in levels agglomeration is associated with higher productivity.

Advanced optimal extraction for the Spitzer/IRS

We present new advances in the spectral extraction of point-like sources adapted to the Infrared Spectrograph onboard the Spitzer Space Telescope. For the first time, we created a super-sampled point spread function of the low-resolution modules. We describe how to use the point spread function to perform optimal extraction of a single source and of multiple sources within the slit. We also examine the case of the optimal extraction of one or several sources with a complex background. The new algorithms are gathered in a plugin called Adopt which is part of the SMART data analysis software.Comment: Accepted for publication in PAS