Impact of Inter-Country Distances on International Tourism

Tourism is a worldwide practice with international tourism revenues increasing from US\$495 billion in 2000 to US\$1340 billion in 2017. Its relevance to the economy of many countries is obvious. Even though the World Airline Network (WAN) is global and has a peculiar construction, the International Tourism Network (ITN) is very similar to a random network and barely global in its reach. To understand the impact of global distances on local flows, we map the flow of tourists around the world onto a complex network and study its topological and dynamical balance. We find that although the WAN serves as infrastructural support for the ITN, the flow of tourism does not correlate strongly with the extent of flight connections worldwide. Instead, unidirectional flows appear locally forming communities that shed light on global travelling behaviour inasmuch as there is only a 15% probability of finding bidirectional tourism between a pair of countries. We conjecture that this is a consequence of one-way cyclic tourism by analyzing the triangles that are formed by the network of flows in the ITN. Finally, we find that most tourists travel to neighbouring countries and mainly cover larger distances when there is a direct flight, irrespective of the time it takes

Spatial and temporal organization of a coastal lagoon fish community: Ria de Aveiro, Portugal

The fish community and its spatial and temporal organization were studied in the Ria de Aveiro. This lagoon system (43 km2 in area), has both marine and fluvial influences and is located between 40º 30’ - 40º 52’N and 8º35’ - 8º 47’W on the central coast of Portugal. The ichthyofauna was sampled monthly, from December 1996 to November 1997, at nine selected stations, with “chincha”, a traditionally-used beach-seine-type net of the region. A total of 14,598 specimens representing 43 species from 21 families were caught. The abiotic parameters (temperature, salinity and dissolved oxygen) showed significant seasonal variations, although only salinity and transparency showed statistically significant trends among sampling stations. The diversity and evenness were greater at the borders of the lagoon. The species richness, diversity and evenness peaked in mid-Summer. Marine seasonal migrant species were the most numerous, and the marine juvenile and estuarine resident categories had the highest number of species. Species number and diversity of the ecological guilds showed some spatio-temporal patterns due to some particular dominant species. Mugilidae, Atherinidae, Moronidae and Clupeidae were the most abundant families. Six species were dominant and represented more than 74% of the total fish abundance, although they did not occur over the whole lagoon area or during the whole sampling period. The study concludes that the fish community of the Ria de Aveiro has well-defined seasonal and spatial patterns.Organis ation spatiale et temporelle de la communauté de poissons d’une lagune côtière – Ria de Aveiro, Portugal. La communauté de poissons et son organisation spatiale et temporelle ont été étudiées dans la Ria de Aveiro. Ce système de lagune (43 km2 de superficie) subit des influences maritimes et fluviales et est situé entre 40º 30’ - 40º 52’N et 8º35’ - 8º 47’W sur la côte centrale du Portugal. Des échantillons ont été prélevés mensuellement de décembre 1996 à novembre 1997, dans neuf stations, avec un filet de pêche traditionnel de la région, la “chincha”. Au total 14 2 598 spécimens ont été collectés représentant 43 espèces et 21 familles. Les paramètres abiotiques (température, salinité et oxygène dissou) ont montré des variations saisonnières significatives, tandis que sur l’ensemble des stations de prélèvement seules la salinité et la transparence ont présenté une variation significative. La diversité et l’équatibilité ont été maximales le long des rives de la lagune. La richesse en espèces, diversité et équatibilité ont leur maximum été. Les espèces marines étaient les plus nombreuses et les catégories “juvénile marin” et “résident estuarien” sont celles qui avaient le plus grand nombre d’espèces. Le nombre d’espèces et la diversité des catégories écologiques ont montré des patterns liés à certaines espèces dominantes. Mugilidae, Atherinidae, Moronidae et Clupeidae étaient les familles les plus abondantes. Six espèces dominaient, même si elles n’étaient pas présentes sur toute la superficie de la lagune ou durant toute la période des échantillons, représentant plus de 74% du total de l’abondance en poisson. Cette étude permet de conclure que la communauté de poisson de la Ria de Aveiro a des patrons saisonniers et spatiaux très bien définis

Vibration of the railway track-viaduct system under moving vehicles taking into account the interaction effect

Vibration of the railway track-viaduct system under moving vehicles taking into account the interaction effec

Influência das irregularidades da via na resposta dinâmica de pontes ferroviárias de médio vão

As irregularidades na via-férrea influenciam o comportamento dinâmico das pontes ferroviárias e aumentam os efeitos dinâmicos produzidos pela passagem dos eixos do comboio. Neste estudo é analisada a influência das irregularidades da via-férrea na resposta dinâmica de uma ponte, cuja primeira frequência natural de vibração se encontra sobre os limites definidos no Eurocódigo 1. São consideradas diferentes irregularidades, isolada a meio-vão e contínua de amplitude aleatória existente em toda a extensão do carril. As respostas máximas da ponte com as irregularidades são determinadas em termos de deslocamentos e acelerações, e comparadas com as obtidas sem as irregularidades. Recorre-se ao modelo dinâmico de via-férrea balastrada ERRI. São analisadas as acelerações na massa vibrante do balastro via-férrea bem como as forças de contacto entre a roda e o carril

Chronic hemolytic anemia is associated with a new glucose-6-phosphate dehydrogenase in-frame deletion in an older woman

Glucose-6-phosphate dehydrogenase (G6PD) deficiency, an X-linked disorder, is usually observed in hemizygote males and very rarely in females. The G6PD class 1 variants, very uncommon, are associated with chronic hemolytic anemia. Here we report a Portuguese woman who suffered in her sixties from a chronic hemolytic anemia due to G6PD deficiency. Molecular studies revealed heterozygosity for an in-frame 18-bp deletion, mapping to exon 10 leading to a deletion of 6 residues, 362-367 (LNERKA), which is a novel G6PD class 1 variant, G6PD Tondela. Two of her three daughters, asymptomatic, with G6PD activity within the normal range, are heterozygous for the same deletion. The patient's leukocyte and reticulocyte mRNA studies revealed an almost exclusive expression of the mutant allele, explaining the chronic hemolytic anemia. Patient whole blood genomic DNA HUMARA assay showed a balanced pattern of X chromosome inactivation (XCI), but granulocyte DNA showed extensive skewing, harboring the mutated allele, implying that in whole blood, lymphocyte DNA, with a very long lifetime, may cover up the current high XCI skewing. This observation indicates that HUMARA assay in women should be assessed in granulocytes and not in total leukocytes

Experimental study of single span railway bridges

The main purpose of this paper is to present some results concerning the investigation that has been done by the authors regarding the dynamic response of small to médium span railway bridges using response acceleration data colleted during the measurements carried out on single span bridges on the railway track Linz-Wels, in Austria. Using output-only methods in this experimental program, it was possible to have an estimation of the igenfrequencies, mode shapes and the corresponding viscous damping. Due to the fact that the bridges were of the same type some generalizations concerning their structural behavior was possible and finite element models were calibrated in order to compute responses for real traffic. The numerical model of the bridges takes into account the track and the real boundary conditions of the decks. The measured and the computed acceleration responses of the track/bridge system are compared using two methods: the moving forces method and the interaction vehicle/track/bridge method

Radiocarbon and blue optically stimulated luminescence chronologies of the Oitavos consolidated dune (Western Portugal)

The dune of Oitavos, the underlying paleosol, and Helix sp. gastropod shells found within the paleosol were dated using a combination of radiocarbon and blue optically stimulated luminescence (OSL). The organic component of the paleosol produced a significantly older age (~20,000 cal BP) than the OSL age measurement (~15,000 yr), while 14C age measurements on the inorganic component and the gastropods produced ages of ~35,000 yr and ~34,000 yr, respectively. Rare-earth element analyses provide evidence that the gastropods incorporate geological carbonate, making them an unreliable indicator of the age of the paleosol. We propose that the 14C age of the small organic component of the paleosol is also likely to be unreliable due to incorporation of residual material. The OSL age measurement of the upper paleosol (~15,000 yr) is consistent with the age for the base of the dune (~14,500 yr). The younger OSL age for the top of the dune (~12,000 yr) suggests that it was built up by at least 2 sand pulses or that there was a remobilization of material at the top during its evolution, prior to consolidation

A nonpolynomial collocation method for fractional terminal value problems

NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Computational and Applied Mathematics. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Computational and Applied Mathematics, 275, February 2015, doi: 10.1016/j.cam.2014.06.013In this paper we propose a non-polynomial collocation method for solving a class of terminal (or boundary) value problems for differential equations of fractional order α, 0 < α < 1. The approach used is based on the equivalence between a problem of this type and a Fredholm integral equation of a particular form. Taking into account the asymptotic behaviour of the solution of this problem, we propose a non-polynomial collocation method on a uniform mesh. We study the order of convergence of the proposed algorithm and a result on optimal order of convergence is obtained. In order to illustrate the theoretical results and the performance of the method we present several numerical examples.The work was supported by an International Research Excellence Award funded through the Santander Universities scheme

An implicit finite difference approximation for the solution of the diffusion equation with distributed order in time

In this paper we are concerned with the numerical solution of a diffusion equation in which the time order derivative is distributed over the interval [0,1]. An implicit numerical method is presented and its unconditional stability and convergence are proved. A numerical example is provided to illustrate the obtained theoretical results