106 research outputs found

    A Survey on Alliances and Related Parameters in Graphs

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    In this paper, we show that several graph parameters are known in different areas under completely different names.More specifically, our observations connect signed domination, monopolies, α\alpha-domination, α\alpha-independence,positive influence domination,and a parameter associated to fast information propagationin networks to parameters related to various notions of global rr-alliances in graphs.We also propose a new framework, called (global) (D,O)(D,O)-alliances, not only in order to characterizevarious known variants of alliance and domination parameters, but also to suggest a unifying framework for the study of alliances and domination.Finally, we also give a survey on the mentioned graph parameters, indicating how results transfer due to our observations

    Alliance free and alliance cover sets

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    A \emph{defensive} (\emph{offensive}) kk-\emph{alliance} in Γ=(V,E)\Gamma=(V,E) is a set SVS\subseteq V such that every vv in SS (in the boundary of SS) has at least kk more neighbors in SS than it has in VSV\setminus S. A set XVX\subseteq V is \emph{defensive} (\emph{offensive}) kk-\emph{alliance free,} if for all defensive (offensive) kk-alliance SS, SXS\setminus X\neq\emptyset, i.e., XX does not contain any defensive (offensive) kk-alliance as a subset. A set YVY \subseteq V is a \emph{defensive} (\emph{offensive}) kk-\emph{alliance cover}, if for all defensive (offensive) kk-alliance SS, SYS\cap Y\neq\emptyset, i.e., YY contains at least one vertex from each defensive (offensive) kk-alliance of Γ\Gamma. In this paper we show several mathematical properties of defensive (offensive) kk-alliance free sets and defensive (offensive) kk-alliance cover sets, including tight bounds on the cardinality of defensive (offensive) kk-alliance free (cover) sets

    Ingeniería Forestal y ambiental en medios insulares

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    Las Islas Canarias a pesar de su reducida extensión y del relativo poco peso específico a nivel mundial, no es ajena a los problemas globales detectados en la conservación de bosques y en la importancia que éstos tienen para obtener beneficios económicos, socioculturales y ambientales. La gestión forestal sostenible es en este sentido esencial para asegurar y compatibilizar los diversos beneficios del bosque. El papel específico de los bosques y su gestión son sin embargo temas aún por conocer en nuestras islas, por lo que el Año Internacional de los Bosques ha representado una oportunidad única para dar a conocer el mundo forestal y acercarlo a nuestra sociedad. El presente libro consta de 25 capítulos donde se ha contemplado la mayoría de los aspectos a tener en cuenta en la planificación y gestión del medio forestal y natural. Desde la historia forestal del archipiélago, hasta el uso y técnicas de manejo de los recursos naturales, incluyendo el agua, la energía en forma de biomasa y la selvicultura

    Equity in the delivery of community healthcare to older people: findings from 10/66 Dementia Research Group cross-sectional surveys in Latin America, China, India and Nigeria

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    <p>Abstract</p> <p>Background</p> <p>To describe patterns of recent health service utilisation, and consequent out-of-pocket expenses among older people in countries with low and middle incomes, and to assess the equity with which services are accessed and delivered.</p> <p>Methods</p> <p>17,944 people aged 65 years and over were assessed in one-phase population-based cross-sectional surveys in geographically-defined catchment areas in nine countries - urban and rural sites in China, India, Mexico and Peru, urban sites in Cuba, Dominican Republic, Puerto Rico and Venezuela, and a rural site in Nigeria. The main outcome was use of community health care services in the past 3 months. Independent associations were estimated with indicators of need (dementia, depression, physical impairments), predisposing factors (age, sex, and education), and enabling factors (household assets, pension receipt and health insurance) using Poisson regression to generate prevalence ratios and fixed effects meta-analysis to combine them.</p> <p>Results</p> <p>The proportion using healthcare services varied from 6% to 82% among sites. Number of physical impairments (pooled prevalence ratio 1.37, 95% CI 1.26-1.49) and ICD-10 depressive episode (pooled PR 1.21, 95% CI 1.07-1.38) were associated with service use, but dementia was inversely associated (pooled PR 0.93, 95% CI 0.90-0.97). Other correlates were female sex, higher education, more household assets, receiving a pension, and health insurance. Standardisation for age, sex, physical impairments, depression and dementia did not explain variation in service use. There was a strong borderline significant ecological correlation between the proportion of consultations requiring out-of-pocket costs and the prevalence of health service use (r = -0.50, p = 0.09).</p> <p>Conclusions</p> <p>While there was little evidence of ageism, inequity was apparent in the independent enabling effects of education and health insurance cover, the latter particularly in sites where out-of-pocket expenses were common, and private health insurance an important component of healthcare financing. Variation in service use among sites was most plausibly accounted for by stark differences in the extent of out-of-pocket expenses, and the ability of older people and their families to afford them. Health systems that finance medical services through out-of-pocket payments risk excluding the poorest older people, those without a secure regular income, and the uninsured.</p

    Ageing and dementia in low and middle income countries - Using research to engage with public and policy makers

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    Abstract While two thirds of the 24 million people with dementia worldwide live in low and middle income countries, very little research has been conducted to support policy making in these regions. Among the non-communicable diseases, dementia (in common with other chronic NCDs linked more to long-term disability than to mortality) has been relatively under-prioritized. International agreements, plans and policy guidelines have called for an end to ageist discrimination and a focus upon reducing disadvantage arising from poverty and the consequences of ill health. Social protection, access to good quality age-appropriate healthcare and addressing the problem of disability are all key issues. However, as yet, little progress has been made in addressing these concerns. In this review we outline the current international policy agenda for older individuals, and its specific relevance to those with dementia and other disabling non-communicable diseases. We consider the potential for epidemiological research to raise awareness, refine the policy agenda, and promote action, using the example of the dissemination strategy developed by the 10/66 Dementia Research Group

    Measurements of Cloud Base Height and Coverage using Elastic Multiangle Lidar Scans at the Pierre Auger Observatory

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    Combined fit to the spectrum and composition data measured by the Pierre Auger Observatory including magnetic horizon effects

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    The measurements by the Pierre Auger Observatory of the energy spectrum and mass composition of cosmic rays can be interpreted assuming the presence of two extragalactic source populations, one dominating the flux at energies above a few EeV and the other below. To fit the data ignoring magnetic field effects, the high-energy population needs to accelerate a mixture of nuclei with very hard spectra, at odds with the approximate E2^{-2} shape expected from diffusive shock acceleration. The presence of turbulent extragalactic magnetic fields in the region between the closest sources and the Earth can significantly modify the observed CR spectrum with respect to that emitted by the sources, reducing the flux of low-rigidity particles that reach the Earth. We here take into account this magnetic horizon effect in the combined fit of the spectrum and shower depth distributions, exploring the possibility that a spectrum for the high-energy population sources with a shape closer to E2^{-2} be able to explain the observations

    Studies of the mass composition of cosmic rays and proton-proton interaction cross-sections at ultra-high energies with the Pierre Auger Observatory

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    In this work, we present an estimate of the cosmic-ray mass composition from the distributions of the depth of the shower maximum (Xmax) measured by the fluorescence detector of the Pierre Auger Observatory. We discuss the sensitivity of the mass composition measurements to the uncertainties in the properties of the hadronic interactions, particularly in the predictions of the particle interaction cross-sections. For this purpose, we adjust the fractions of cosmic-ray mass groups to fit the data with Xmax distributions from air shower simulations. We modify the proton-proton cross-sections at ultra-high energies, and the corresponding air shower simulations with rescaled nucleus-air cross-sections are obtained via Glauber theory. We compare the energy-dependent composition of ultra-high-energy cosmic rays obtained for the different extrapolations of the proton-proton cross-sections from low-energy accelerator data

    Study of downward Terrestrial Gamma-ray Flashes with the surface detector of the Pierre Auger Observatory

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    The surface detector (SD) of the Pierre Auger Observatory, consisting of 1660 water-Cherenkov detectors (WCDs), covers 3000 km2 in the Argentinian pampa. Thanks to the high efficiency of WCDs in detecting gamma rays, it represents a unique instrument for studying downward Terrestrial Gamma-ray Flashes (TGFs) over a large area. Peculiar events, likely related to downward TGFs, were detected at the Auger Observatory. Their experimental signature and time evolution are very different from those of a shower produced by an ultrahigh-energy cosmic ray. They happen in coincidence with low thunderclouds and lightning, and their large deposited energy at the ground is compatible with that of a standard downward TGF with the source a few kilometers above the ground. A new trigger algorithm to increase the TGF-like event statistics was installed in the whole array. The study of the performance of the new trigger system during the lightning season is ongoing and will provide a handle to develop improved algorithms to implement in the Auger upgraded electronic boards. The available data sample, even if small, can give important clues about the TGF production models, in particular, the shape of WCD signals. Moreover, the SD allows us to observe more than one point in the TGF beam, providing information on the emission angle
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