The blooming of location-sharing services has led to serious privacy concerns, particularly location privacy concerns. In this paper, we first discuss the definition of location privacy and then review several location privacy protection mechanisms. After that, we classify location privacy protection mechanisms into four categories: legislation & regulatory, anonymity & obfuscation, protocol an...

The universal C*-algebra generated by n projections has been described. As an immediate corollary one obtains structure theorem for a pair of projections and the solution to an associated index problem. This puts the study of a pair of projections in the proper perspective of noncommutative geometry. keyword: Index problem, crossed product, Fredholm module, pair of projections. MSC 46L87.

The surrounding of a vertex in a network can be more or less symmetric. We derive measures of a specific kind of symmetry of a vertex which we call degree symmetry--the property that many paths going out from a vertex have overlapping degree sequences. These measures are evaluated on artificial and real networks. Specifically we consider vertices in the human metabolic network. We also measure ...

In this work, we explore the relations between sales growth and a set of innovation indicators that capture the different sources, modes and results of the innovative activity undertaken within firms. We exploit a rich panel on innovation activity of Spanish manufacturing firms, reporting detailed CIS-type information continuously over the period 2004-2011. Standard GMMpanel estimates of the av...

OBJECTIVES. Responsiveness has been identified as one of the intrinsic goals of health care systems. Little is known, however, about its determinants. Our objective is to investigate the potential country-level drivers of health system responsiveness. DATA SOURCE. Data on responsiveness are taken from the World Health Survey. Information on country-level characteristics is obtained from a varie...

We show that, for any rotationally symmetric projection with a single virtual viewpoint, it is possible to design a two-mirror rotationally symmetric system that realizes the projection exactly. These mirror pairs are derived from two coupled differential equations. We give examples in which the projections from the sphere at infinity are stereographic, perspective, and equiresolution.

The authors conducted a meta-analysis of the relationship between turnover rates and organizational performance to (a) determine the magnitude of the relationship; (b) test organization-, context-, and methods-related moderators of the relationship; and (c) suggest future directions for the turnover literature on the basis of the findings. The results from 300 total correlations (N = 309,245) a...

PURPOSE To investigate the dynamics of volunteering in the population aged 50 years or older across 11 Continental European countries. DESIGN AND METHODS Using longitudinal data from the first 2 waves of the Survey of Health, Ageing and Retirement in Europe, we run multivariate regressions on a set of binary-dependent variables indicating transitions from active volunteering to inactivity and...

Let Γ = G1 ∗G2 ∗ ... ∗Gn ∗ ... be a free product of at least two but at most countably many cyclic groups. With each such group Γ we associate a family of C*-algebras, denoted C∗ r (Γ,PΛ) and generated by the reduced group C*-algebra C∗ r Γ and a collection PΛ of projections onto the `2-spaces over certain subsets of Γ. We determine W ∗(Γ,PΛ), the weak closure of C∗ r (Γ,PΛ) in L(`2(Γ)), and us...

We examine the internal geometry of a Kleinian surface group and its relations to the asymptotic geometry of its ends, using the combinatorial structure of the complex of curves on the surface. Our main results give necessary conditions for the Kleinian group to have ‘bounded geometry’ (lower bounds on injectivity radius) in terms of a sequence of coefficients (subsurface projections) computed ...