Degenerate Feedback Loops in Recommender Systems

Machine learning is used extensively in recommender systems deployed in products. The decisions made by these systems can influence user beliefs and preferences which in turn affect the feedback the learning system receives - thus creating a feedback loop. This phenomenon can give rise to the so-called "echo chambers" or "filter bubbles" that have user and societal implications. In this paper, we provide a novel theoretical analysis that examines both the role of user dynamics and the behavior of recommender systems, disentangling the echo chamber from the filter bubble effect. In addition, we offer practical solutions to slow down system degeneracy. Our study contributes toward understanding and developing solutions to commonly cited issues in the complex temporal scenario, an area that is still largely unexplored

Structural validation of a realistic wing structure: the RIBES test article

Several experimental test cases are available in literature to study and validate fluid structure interaction methods. They, however, focus the attention mainly on replicating typical cruising aerodynamic conditions forcing the adoption of fully steel made models able to operate with the high loads generated in high speed facilities. This translates in a complete loss of similitude with typical realistic aeronautical wing structures configurations. To reverse this trend, and to better study the aerolastic mechanism from a structural point of view, an aeroelastic measurement campaign was carried within the EU RIBES project. A half wing model for wind tunnel tests was designed and manufactured replicating a typical metallic wing box structure, producing a database of loads, pressure, stress and deformation measurements. In this paper the design, manufacturing and validation activities performed within the RIBES project are described, with a focus on the structural behavior of the test article. All experimental data and numerical models are made freely available to the scientific community

Recent progress in the truncated Lanczos method : application to hole-doped spin ladders

The truncated Lanczos method using a variational scheme based on Hilbert space reduction as well as a local basis change is re-examined. The energy is extrapolated as a power law function of the Hamiltonian variance. This systematic extrapolation procedure is tested quantitatively on the two-leg t-J ladder with two holes. For this purpose, we have carried out calculations of the spin gap and of the pair dispersion up to size 2x15.Comment: 5 pages, 4 included eps figures, submitted to Phys. Rev. B; revised versio

Cruise tourism externalities and residents’ support: a generalized ordered logit analysis

This paper investigates residents’ preferences towards cruise tourism investment in their home port. The research uses data collected during the peak cruise season in 2011 at Messina, a port of call in Sicily, Italy. A generalized ordered logit analysis is run to analyse what factors influence the residents’ preferences towards investment in cruise tourism. Positive and negative externalities produced by this economic activity, as well as socio-demographic and economic determinants are taken into account. Overall, the resource investment choice of residents in Messina was dependet upon: their income dependency on the cruise activity, their own personal cruise experience, family size, the expected increase in welfare (i.e. increase in public and private investment), whether they are affected by urban and rural gentrification and the value placed on community life style and heritage conservation. Nevertheless, residents would tend to decrease investments in cruise activity if they are female, retired or perceive the environment to be deteriorating. Implications for policy makers are drawn from the empirical findings

Superplastic Behaviour of an Mg-Ag-RE Magnesium Alloy

Fine-grained magnesium alloy QE22 (Mg-2.5wt.%Ag-2.5wt.%RE-0.6wt.%Zr) was prepared from cast ingot which was submitted to a two stages heat treatment. Subsequently the billet was overaged and extruded at high temperature. Samples were deformed at elevated temperatures from 380 °C up to 480 °C at various strain rates. Microstructure of deformed samples was studied using light and electron microscopy. Conditions for superplasticity of the investigated alloys have been estimated. Possible deformation mechanisms are discussed.JRC.F.4-Innovative Technologies for Nuclear Reactor Safet

Challenges in Italian wine routes: managing stakeholder networks

Purpose – The aim of this article is to analyse how wine and tourism operators understand the concept of a wine route, in order to determine the impact that definition can have on the extent to which stakeholders working within distinct, but related sectors (namely wine production, tourism, food and hospitality) collaborate with each other and share knowledge. Design/methodology/approach – By adopting the theoretical lens of “boundary objects” (understood as tangible or intangible entities that allow the sharing of meaning to different groups and facilitate collaboration), this article uses a qualitative approach, based on semi-structured interviews of 20 informants working in three different wine routes in Italy. Analysis of data is carried out in order to highlight the similarities and differences between the wine and tourism (including identified associated service) industries. Findings – Wine routes can be considered boundary objects that, if clearly defined by local stakeholders, can facilitate knowledge sharing and collaboration. Problems in collaboration could be explained by an initial mis-definition by stakeholders of what a wine route and its remit are. Research limitations – Since the theoretical lens of “boundary objects” was applied for the first time to wine routes and tourism, further research is necessary in order to validate its application. Practical implications – It is suggested that managers of wine routes involve all stakeholders in discussions to achieve a common understanding on what a wine route is and its role in the promotion of “place” (geographical context of the wine route). Only if this is done successfully, is it possible to achieve collaboration. Originality/value of the paper – This article uses the concept of “boundary objects” (a concept traditionally applied to the study of innovation) to the analysis of wine routes, and provides further theoretical and managerial insights concerning networking between wine and tourism sectors, taking a supply-side perspective