8,492 research outputs found

    Networks of Gratitude: Structures of Thanks and User Expectations in Workplace Appreciation Systems

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    Appreciation systems--platforms for users to exchange thanks and praise--are becoming common in the workplace, where employees share appreciation, managers are notified, and aggregate scores are sometimes made visible. Who do people thank on these systems, and what do they expect from each other and their managers? After introducing the design affordances of 13 appreciation systems, we discuss a system we call Gratia, in use at a large multinational company for over four years. Using logs of 422,000 appreciation messages and user surveys, we explore the social dynamics of use and ask if use of the system addresses the recognition problem. We find that while thanks is mostly exchanged among employees at the same level and different parts of the company, addressing the recognition problem, managers do not always act on that recognition in ways that employees expect.Comment: in Tenth International AAAI Conference on Web and Social Media, 201

    Boundary stress tensor and asymptotically AdS3 non-Einstein spaces at the chiral point

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    Chiral gravity admits asymptotically AdS3 solutions that are not locally equivalent to AdS3; meaning that solutions do exist which, while obeying the strong boundary conditions usually imposed in General Relativity, happen not to be Einstein spaces. In Topologically Massive Gravity (TMG), the existence of non-Einstein solutions is particularly connected to the question about the role played by complex saddle points in the Euclidean path integral. Consequently, studying (the existence of) non-locally AdS3 solutions to chiral gravity is relevant to understand the quantum theory. Here, we discuss a special family of non-locally AdS3 solutions to chiral gravity. In particular, we show that such solutions persist when one deforms the theory by adding the higher-curvature terms of the so-called New Massive Gravity (NMG). Moreover, the addition of higher-curvature terms to the gravity action introduces new non-locally AdS3 solutions that have no analogues in TMG. Both stationary and time-dependent, axially symmetric solutions that asymptote AdS3 space without being locally equivalent to it appear. Defining the boundary stress-tensor for the full theory, we show that these non-Einstein geometries have associated vanishing conserved charges.Comment: 8 pages. v2 minor typos correcte

    Counting the negative eigenvalues of the thermalon in three dimensions

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    Some years ago it was shown that the cosmological constant may be reduced by thermal production of membranes that, after nucleation, collapse into a black hole. The probability of the process was calculated in the leading semiclassical approximation by studying an associated Euclidean configuration called the thermalon. Here we investigate the thermalon in three spacetime dimensions, describing the nucleation of closed strings that collapse into point particle singularities. In this context we may analyze the one-loop structure without the well known problems brought in by the propagating gravitational degrees of freedom. We found that the coupling to gravity may increase the number of negative eigenvalues of the operator

    Differential Privacy: on the trade-off between Utility and Information Leakage

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    Differential privacy is a notion of privacy that has become very popular in the database community. Roughly, the idea is that a randomized query mechanism provides sufficient privacy protection if the ratio between the probabilities that two adjacent datasets give the same answer is bound by e^epsilon. In the field of information flow there is a similar concern for controlling information leakage, i.e. limiting the possibility of inferring the secret information from the observables. In recent years, researchers have proposed to quantify the leakage in terms of R\'enyi min mutual information, a notion strictly related to the Bayes risk. In this paper, we show how to model the query system in terms of an information-theoretic channel, and we compare the notion of differential privacy with that of mutual information. We show that differential privacy implies a bound on the mutual information (but not vice-versa). Furthermore, we show that our bound is tight. Then, we consider the utility of the randomization mechanism, which represents how close the randomized answers are, in average, to the real ones. We show that the notion of differential privacy implies a bound on utility, also tight, and we propose a method that under certain conditions builds an optimal randomization mechanism, i.e. a mechanism which provides the best utility while guaranteeing differential privacy.Comment: 30 pages; HAL repositor

    Représentations, modèles normatifs et compétences sociales : une étude exploratoire dans un lycée sensible en Espagne.

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    This exploratory research conducted in a Spanish Secondary school proposes to structure the study of social representations with the domain of social competencies and is in line with the psychology of social education. The rapid social changes in Spain during the last decades have had a strong influence on education. A number of school conflicts linked to social interaction are at the origin of a vast variety of intervention programs focused on the development of student social skills. From this perspective, it is necessary to take the representations of different community members (families, students, teachers) into account. To evaluate students’ « social skills » a questionnaire was administered in a secondary school located in a deprived area of Madrid. In order to study families’ and teachers’ reference models, we substituted instructions in pro conditions (well-viewed) and against-normative conditions (badly-viewed). Factor analysis in the main components of the different normative models detects an interesting Guttman effect. Results show a social competence representation linked to the behavior expectations promoted by traditional society. With peers, this representation is not adapted to favourable individual and social development
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