7,440 research outputs found

    Random l-colourable structures with a pregeometry

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    We study finite ll-colourable structures with an underlying pregeometry. The probability measure that is used corresponds to a process of generating such structures (with a given underlying pregeometry) by which colours are first randomly assigned to all 1-dimensional subspaces and then relationships are assigned in such a way that the colouring conditions are satisfied but apart from this in a random way. We can then ask what the probability is that the resulting structure, where we now forget the specific colouring of the generating process, has a given property. With this measure we get the following results: 1. A zero-one law. 2. The set of sentences with asymptotic probability 1 has an explicit axiomatisation which is presented. 3. There is a formula Ο(x,y)\xi(x,y) (not directly speaking about colours) such that, with asymptotic probability 1, the relation "there is an ll-colouring which assigns the same colour to xx and yy" is defined by Ο(x,y)\xi(x,y). 4. With asymptotic probability 1, an ll-colourable structure has a unique ll-colouring (up to permutation of the colours).Comment: 35 page

    Experimental observation of the trapped rainbow

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    We report on the first experimental demonstration of the broadband "trapped rainbow" in the visible frequency range using an adiabatically tapered waveguide. Being a distinct case of the slow light phenomenon, the trapped rainbow effect could be applied to optical computing and signal processing, and to providing enhanced light-matter interactions.Comment: 2 pages, 1 figur

    Tourist spaces and tourism policy in Spain and Portugal

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    Advances in Cultura, Tourism and Hospitality Research;10, 235-249This study analyses the relationship between the development of the tourism policy of Spain and Portugal and their effects on regional imbalances. Despite the proximity of the two countries and their specialisation in tourism, there are few comparative studies on tourism of the two Iberian countries. The study focuses on the two major phases of tourism policy: the period of mass tourism and post-Fordist stage. In the conclusions we refer the debate on the existence of a model of development based on tourism to the Latin countries of Southern Europe and we note the export process of the Spanish low-cost tourism model to other countries.Financiado por el Gobierno de España, Programa Fundamental de Investigación, Proyecto de I+D (CSO2012-30840) "Geografías de la crisis: anålisis de los territorios urbanos y turísticos de las Islas Baleares, Costa del Sol y principales destinos del Caribe y América Central"

    Effect of two different participant information sheets on recruitment to a falls trial:an embedded randomised recruitment trial

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    Background/Aims: Recruitment to trials of intervention for older people who fall is challenging. Evidence suggests that the word falls has negative connotations for older people, and this may present a barrier to engaging with trials in this area. We therefore tested whether a participant information sheet that minimised reference to falls could improve recruitment rates. Methods: We conducted a study within a trial, embedded within a randomised controlled trial of vitamin K versus placebo to improve postural sway in patients aged 65 and over with a history of falls. Potential participants were identified from primary care lists in 14 practices and were randomised to receive either a standard participant information sheet or an information sheet minimising use of the word falls, instead focussing on maintenance of health, fitness and balance. The primary outcome for this embedded trial was the proportion of responses expressing interest in participating received in each arm. Secondary outcomes were the proportion of those contacted attending a screening visit, consenting at screening, and the proportion contacted who were randomised into the main trial. Results: In all, 4145 invitations were sent, with an overall response rate of 444 (10.7%). In all, 2148 individuals received the new information sheet (minimising reference to falls); 1997 received the standard information sheet. There was no statistically significant difference in response rate between those individuals sent the new information sheet and those sent the standard information sheet (10.1% vs 11.4%; difference 1.3% (95% confidence interval -0.6% to 3.2%); p = 0.19). Similarly, we found no statistically significant difference between the percentage of those who attended and consented at screening in the two groups (2.1% vs 2.7%; difference 0.6% (95% confidence interval: -0.4% to 1.6%); p = 0.20), and no statistically significant difference between the percentage randomised in the two groups (2.0% vs 2.6%; difference 0.6% (95% confidence interval -0.4% to 1.6%); p = 0.20). Conclusions: Use of a participant information sheet minimising reference to falls did not lead to a greater response rate in this trial targeting older people with a history of falls.</p

    On global models for isolated rotating axisymmetric charged bodies; uniqueness of the exterior field

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    A relatively recent study by Mars and Senovilla provided us with a uniqueness result for the exterior vacuum gravitational field generated by an isolated distribution of matter in axial rotation in equilibrium in General Relativity. The generalisation to exterior electrovacuum gravitational fields, to include charged rotating objects, is presented here.Comment: LaTeX, 21 pages, uses iopart styl

    Investigation of the role of morphology on the magnetic properties of Ca2Mn3O8 materials

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    Ca2Mn3O8 exhibits a complex layered structure comprised of Mn3O84- layers separated by Ca2+ ions. In contrast with the more traditional triangular Delafossite layered materials the Mn3O84- layers additionally exhibit an ordered vacancy which forms a 'bow-tie' like arrangement of the Mn4+ ions. We report a comprehensive study of the magnetic properties of a series of Ca2Mn3O8 materials with different morphologies. EXAFS and XANES analysis confirm no differences in either manganese environment or oxidation state between materials. Apparent differences in magnetic order from SQUID magnetometry can be rationalised by uncompensated surface spins arising as a result of changes to the surface:volume ratio between morphologies. Furthermore, these data suggest these materials are potentially frustrated in nature, due to the triangular connectivity of Mn4+ spins with a simple ‘spin-up/spin-down’ (↑↓) antiferromagnetic model unable to explain the data collected

    Extracellular vesicles from airway secretions: New insights in lung diseases

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    Lung diseases (LD) are one of the most common causes of death worldwide. Although it is known that chronic airway inflammation and excessive tissue repair are processes associated with LD such as asthma, chronic obstructive pulmonary disease (COPD) or idiopathic pulmonary fibro-sis (IPF), their specific pathways remain unclear. Extracellular vesicles (EVs) are heterogeneous na-noscale membrane vesicles with an important role in cell-to-cell communication. EVs are present in general biofluids as plasma or urine but also in secretions of the airway as bronchoalveolar lavage fluid (BALF), induced sputum (IS), nasal lavage (NL) or pharyngeal lavage. Alterations of airway EV cargo could be crucial for understanding LD. Airway EVs have shown a role in the pathogenesis of some LD such as eosinophil increase in asthma, the promotion of lung cancer in vitro models in COPD and as biomarkers to distinguishing IPF in patients with diffuse lung diseases. In addition, they also have a promising future as therapeutics for LD. In this review, we focus on the importance of airway secretions in LD, the pivotal role of EVs from those secretions on their pathophysiology and their potential for biomarker discovery

    Immune-Mediated Inflammation May Contribute to the Pathogenesis of Cardiovascular Disease in Mucopolysaccharidosis Type I.

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    BackgroundCardiovascular disease, a progressive manifestation of α-L-iduronidase deficiency or mucopolysaccharidosis type I, continues in patients both untreated and treated with hematopoietic stem cell transplantation or intravenous enzyme replacement. Few studies have examined the effects of α-L-iduronidase deficiency and subsequent glycosaminoglycan storage upon arterial gene expression to understand the pathogenesis of cardiovascular disease.MethodsGene expression in carotid artery, ascending, and descending aortas from four non-tolerized, non-enzyme treated 19 month-old mucopolysaccharidosis type I dogs was compared with expression in corresponding vascular segments from three normal, age-matched dogs. Data were analyzed using R and whole genome network correlation analysis, a bias-free method of categorizing expression level and significance into discrete modules. Genes were further categorized based on module-trait relationships. Expression of clusterin, a protein implicated in other etiologies of cardiovascular disease, was assessed in canine and murine mucopolysaccharidosis type I aortas via Western blot and in situ immunohistochemistry.ResultsGene families with more than two-fold, significant increased expression involved lysosomal function, proteasome function, and immune regulation. Significantly downregulated genes were related to cellular adhesion, cytoskeletal elements, and calcium regulation. Clusterin gene overexpression (9-fold) and protein overexpression (1.3 to 1.62-fold) was confirmed and located specifically in arterial plaques of mucopolysaccharidosis-affected dogs and mice.ConclusionsOverexpression of lysosomal and proteasomal-related genes are expected responses to cellular stress induced by lysosomal storage in mucopolysaccharidosis type I. Upregulation of immunity-related genes implicates the potential involvement of glycosaminoglycan-induced inflammation in the pathogenesis of mucopolysaccharidosis-related arterial disease, for which clusterin represents a potential biomarker
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