3,116 research outputs found

    Northern European retired residents in nine southern European areas: characteristics, motivations and adjustment

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    During the last two decades, northern European retirement residence in the southern European sunbelt has grown strongly and its forms have rapidly changed, but standard demographic and social statistical sources provide no information about the flows, the migrants or their increasingly mobile and complex residential patterns. Considerable primary research has however recently been undertaken into the causes, conditions, experiences and consequences of international retirement migration (IRM) by investigators from Germany, Spain, Switzerland and the United Kingdom. Many collaborated when designing their studies and instruments, and all have subsequently worked together in a European Science Foundation Scientific Network. This paper compares the findings of six systematic social surveys in (to be more precise than the title) eight regions of southern Europe and the Canary Islands: all that have tackled similar research questions with similar methods and instruments. It presents interpretations of several comparative tables compiled from their original data, with a focus on the socio-economic backgrounds, motivations and behaviour of the various migrant groups and their relationship with the host and home countries. The paper presents new findings about the typical and variant forms of IRM, and additional understanding of the heterogeneity of the retirees of different nations and in the several regions

    Anonymity Metrics Revisited

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    In 2001, two information theoretic anonymity metrics were proposed: the "effective anonymity set size" and the "degree of anonymity". In this talk, we propose an abstract model for a general anonymity system which is consistent with the definition of anonymity on which the metrics are based. We revisit entropy-based anonymity metrics, and we apply them to Crowds, a practical anonymity system. We discuss the differences between the two metrics and the results obtained in the example

    The Evolution of the Bel Canto Technique Through the 20th and 21st Century: Annotated Bibliography

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    The Bel canto technique is the quintessential technique of opera performance. Throughout history, it has adapted itself and survived through pedagogies, composers, influential artists, and scientific specialists from the field. Although the bel canto technique has a wide range of sources and complete history, this will focus more on the evolution occurring through the 20th and 21st centuries. How the bel canto technique has managed to survive is key to understanding its future

    On the Measurement of Privacy as an Attacker's Estimation Error

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    A wide variety of privacy metrics have been proposed in the literature to evaluate the level of protection offered by privacy enhancing-technologies. Most of these metrics are specific to concrete systems and adversarial models, and are difficult to generalize or translate to other contexts. Furthermore, a better understanding of the relationships between the different privacy metrics is needed to enable more grounded and systematic approach to measuring privacy, as well as to assist systems designers in selecting the most appropriate metric for a given application. In this work we propose a theoretical framework for privacy-preserving systems, endowed with a general definition of privacy in terms of the estimation error incurred by an attacker who aims to disclose the private information that the system is designed to conceal. We show that our framework permits interpreting and comparing a number of well-known metrics under a common perspective. The arguments behind these interpretations are based on fundamental results related to the theories of information, probability and Bayes decision.Comment: This paper has 18 pages and 17 figure

    Angiotensin-converting enzyme inhibitors stimulate cerebral arteriogenesis

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    A potent stimulatory effect of Angiotensin-converting-enzyme inhibitors (ACEI) on cerebralarteriogenesis, involving bradykinin, was recently demonstrated by Hillmeister et. al, in a ratmodel of three-vessel occlusion. The evidences presented by the authors show clearly that thecollateral growth in the posterior cerebral artery occurs, resulting in blood supply and cerebralautoregulation recovery.Fil: Bregonzio Diaz, Claudia. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - CĂłrdoba. Instituto de FarmacologĂ­a Experimental de CĂłrdoba. Universidad Nacional de CĂłrdoba. Facultad de Ciencias QuĂ­micas. Instituto de FarmacologĂ­a Experimental de CĂłrdoba; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂ­mica. Departamento de FarmacologĂ­a; Argentin

    A sample of Seyfert-2 galaxies with ultra-luminous galaxy-wide NLRs -- Quasar light echos?

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    We report the discovery of Seyfert-2 galaxies in SDSS-DR8 with galaxy-wide, ultra-luminous narrow-line regions (NLRs) at redshifts z=0.2-0.6. With a space density of 4.4 per cubic Gpc at z~0.3, these "Green Beans" (GBs) are amongst the rarest objects in the Universe. We are witnessing an exceptional and/or short-lived phenomenon in the life cycle of AGN. The main focus of this paper is on a detailed analysis of the GB prototype galaxy J2240-0927 (z=0.326). Its NLR extends over 26x44 kpc and is surrounded by an extended narrow-line region (ENLR). With a total [OIII]5008 luminosity of (5.7+/-0.9)x10e43 erg/s, this is one of the most luminous NLR known around any type-2 galaxy. Using VLT/XSHOOTER we show that the NLR is powered by an AGN, and we derive resolved extinction, density and ionization maps. Gas kinematics is disturbed on a global scale, and high velocity outflows are absent or faint. This NLR is unlike any other NLR or extended emission line region (EELR) known. Spectroscopy with Gemini/GMOS reveals extended, high luminosity [OIII] emission also in other GBs. WISE 24micron luminosities are 5-50 times lower than predicted by the [OIII] fluxes, suggesting that the NLRs reflect earlier, very active quasar states that have strongly subsided in less than a galaxies' light crossing time. These light echos are about 100 times more luminous than any other such light echo known to date. X-ray data are needed for photo-ionization modeling and to verify the light echos.Comment: This is an update of our previous submission (1211.7098). Apart from layout it is identical to the publication in ApJ. Compared to v1 (1211.7098) type settings and language errors have been corrected. We also added 4 more redshifts, confirming 3 sources (objects #002, #017, #21) and rejecting one (#020, low-z HII region

    Are compact groups hostile towards faint galaxies?

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    The goal of this work is to understand whether the extreme environment of compact groups can affect the distribution and abundance of faint galaxies around them. We performed an analysis of the faint galaxy population in the vicinity of compact groups and normal groups. We built a light-cone mock galaxy catalogue constructed from the Millennium Run Simulation II plus a semi-analytical model of galaxy formation. We identified a sample of compact groups in the mock catalogue as well as a control sample of normal galaxy groups and computed the projected number density profiles of faint galaxies around the first- and the second-ranked galaxies. We also compared the profiles obtained from the semi-analytical galaxies in compact groups with those obtained from observational data. In addition, we investigated whether the ranking or the luminosity of a galaxy is the most important parameter in the determination of the centre around which the clustering of faint galaxies occurs. There is no particular influence of the extreme compact group environment on the number of faint galaxies in such groups compared to control groups. When selecting normal groups with separations between the 1st and 2nd ranked galaxies similar to what is observed in compact groups, the faint galaxy projected number density profiles in compact groups and normal groups are similar in shape and height. We observed a similar behaviour of the population of faint galaxies in observations and simulations in the regions closer to the 1st and 2nd ranked galaxies. Finally, we find that the projected density of faint galaxies is higher around luminous galaxies,regardless of the ranking in the compact group. The semi-analytical approach shows that compact groups and their surroundings do not represent a hostile enough environment to make faint galaxies to behave differently than in normal groups.Comment: 12 pages, 10 figures. Accepted for publication in Astronomy & Astrophysic

    VerLoc: Verifiable Localization in Decentralized Systems

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    This paper tackles the challenge of reliably determining the geo-location of nodes in decentralized networks, considering adversarial settings and without depending on any trusted landmarks. In particular, we consider active adversaries that control a subset of nodes, announce false locations and strategically manipulate measurements. To address this problem we propose, implement and evaluate VerLoc, a system that allows verifying the claimed geo-locations of network nodes in a fully decentralized manner. VerLoc securely schedules roundtrip time (RTT) measurements between randomly chosen pairs of nodes. Trilateration is then applied to the set of measurements to verify claimed geo-locations. We evaluate VerLoc both with simulations and in the wild using a prototype implementation integrated in the Nym network (currently run by thousands of nodes). We find that VerLoc can localize nodes in the wild with a median error of 60km, and that in attack simulations it is capable of detecting and filtering out adversarial timing manipulations for network setups with up to 20% malicious nodes
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