Improving Reachability and Navigability in Recommender Systems

In this paper, we investigate recommender systems from a network perspective and investigate recommendation networks, where nodes are items (e.g., movies) and edges are constructed from top-N recommendations (e.g., related movies). In particular, we focus on evaluating the reachability and navigability of recommendation networks and investigate the following questions: (i) How well do recommendation networks support navigation and exploratory search? (ii) What is the influence of parameters, in particular different recommendation algorithms and the number of recommendations shown, on reachability and navigability? and (iii) How can reachability and navigability be improved in these networks? We tackle these questions by first evaluating the reachability of recommendation networks by investigating their structural properties. Second, we evaluate navigability by simulating three different models of information seeking scenarios. We find that with standard algorithms, recommender systems are not well suited to navigation and exploration and propose methods to modify recommendations to improve this. Our work extends from one-click-based evaluations of recommender systems towards multi-click analysis (i.e., sequences of dependent clicks) and presents a general, comprehensive approach to evaluating navigability of arbitrary recommendation networks

"Getting Switzerland to move”: E valuation of a new "Sport for All” programme

Summary: Objectives: Even though sports participation in Switzerland appears to be quite elevated, recent research suggests that only about a third of the population are doing enough sports from a health perspective. Methods: Against this background several Swiss health insurance companies together with the Swiss Olympic Association have recently developed a novel approach to get people to start physical exercise: Under the label of > sport clubs offer training and information courses aimed at motivating and helping previously inactive people to take on regular exercise. Results: The paper presents results from an interdisciplinary evaluation of the first three years of the > campaign. Starting from an overview of the basic idea and features of the campaign it asks whether > has reached its self-declared goal of "getting Switzerland moving”. Available evidence on the social background of participants and their further activities shows that by systematically avoiding any reference to conventional notions of sport and by stressing the health and fun aspect instead, > has indeed managed to mobilise an important group with underaverage levels of activity (particularly middle-aged women). In addition, on average the level of physical exercise of participants appears to have increased. Yet, the number of participants is below the original target values and, contrary to the campaign's initial goal, participants are reluctant to leave the programme after one course to take up an independent activity or to join a club. Conclusions: The paper explores the achievements and problems of the campaign so far and offers an explanation of recent problems which can also serve as a basis for the implementation of similar programmes in other countrie

Sport and leisure-time physical activity over the life course

It is desirable to get as many people as possible to engage in long-term leisure-time physical activity (LTPA) due to the health-enhancing effects. Although the proportion of individuals who are physically active in their leisure time appears to have increased in Switzerland in the past years (e.g., Lamprecht et al., 2020), little is known so far about the dynamic of change in LTPA trajectories over the life course. LTPA trajectories of 1,456 Swiss resi- dents aged 35 to 76 years (random sampling) were reconstructed with the help of a retrospective telephone interview (CATI method). To address the dif- ficulties of retrospective data collection, the article presents the careful development of the questionnaire on the basis of current evidence. The majority of the respondents (approx. 73%) show a long-term LTPA without dropout (dropout = LTPA less than once a week over one year and longer), only a minority of whom (approx. 18%) took up their LTPA after the age of 20. In addition, there is also a group with a somewhat unstable LTPA trajectory (approx. 24%) that includes at least one dropout. For members of the latter group, the longer the inactive episode lasted, the lower were their chances of entering an LTPA. While the different LTPA trajectory groups differed only slightly with regard to socioeconomic characteristics, analyses of their sport- and physical activity-related history reveal that self-organized LTPA in child- hood and youth may be seen as a success factor for lifelong LTPA. The pro- portion of people practicing (long-term) LTPA is presumably overrepresented in the sample. This limitation should be taken into account, but analyses of possible advantageous conditions of long-term or lifelong LTPA are neverthe- less possible. The results indicate a demand for more specific theories related to the causality behind the observable LTPA behavio

Physical activity of adults aged 50years and older in Switzerland

Summary.: Objective: This study explores the prevalence of guideline-compliant physical activity (PA) behavior based on socio-demographic, health-related and environmental variables. Methods: Cross-sectional data of the Swiss Health Survey 2002 were used in a Swiss population segment aged 50+. Four categories of PA were created with respect to Swiss and US guidelines: "moderate sports/exercise”, "vigorous sports/exercise”, "habitual PA”, and "optimal PA” (i. e. combined variable used when both "vigorous sports/exercise” and "habitual PA” apply). Sedentary lifestyle was a fifth category. Results: In the total sample considered for analysis (N=8405) the prevalence of guideline-compliant PA was: 9.1% moderate sports/exercise; 18.2% vigorous sports/exercise; 45% habitual PA; 8.7% optimal PA. Almost 50% of the age groups 65-79 and 80+ were involved in habitual PA. Higher socio-economic status was associated with involvement in moderate sports/exercise, vigorous sports/exercise, or optimal PA. In contrast, lower socioeconomic status was associated with habitual PA. While living in an urban or rural environment had no differentiating effect on sports/exercise, living in rural areas was associated with a sedentary lifestyle and little involvement in habitual PA and/or optimal PA. Self-reported good health and/or health orientation were associated with vigorous sports/exercise, habitual PA and optimal PA, regardless of whether the person had chronic health problems or not. Conclusion: Habitual PA seems to have the greatest potential for increasing overall guideline-compliant activity levels. A behavioral/ cognitive and political/environmental approach to improving PA is suggeste

Professionalization and organizational problems of sports clubs: Is there a relationship?

Sports clubs have been reporting several organizational problems in recent decades (e.g., recruitment and retention of members and volunteers). At the same time, certain sports clubs have professionalized their strategies, structures, processes, and staff. However, previous research has not analyzed whether the professionalization of sports clubs is related to their organizational problems. Therefore, this study conducts, in the first step, a cluster analysis based on three dimensions of professionalization to identify professionalization types among sports clubs. In the second step, it examines differences in organizational problems among the identified professionalization types. The main findings are that (1) sports clubs with paid staff report fewer problems with recruiting and retaining members but more problems with finances than sports clubs that rely on voluntary work, and (2) sports clubs with increased professionalization of human resources management (HRM) and strategy have fewer problems with recruiting and retaining board members and coaches than sports clubs with low professionalization of HRM and strategy. These results show that professionalized sports clubs have different, but not necessarily fewer, organizational problems

Integrated optical backplane amplifier

A solution for compensating losses in optical interconnects is provided. Large-core Al2O3:Nd3+ channel waveguide amplifiers are characterized and tested in combination with passive polymer waveguides. Coupling losses between the two waveguides are investigated in order to optimize the channel geometries of the two waveguide types. A tapered Al2O3:Nd3+ waveguide is designed to improve the pump intensity in the active region. A maximum 0.21-dB net gain at a signal wavelength of 880 nm is demonstrated in a structure in which an Al2O3:Nd3+ waveguide is coupled between two polymer waveguides. The gain can be improved by increasing the pump power and adjusting the waveguide properties of the amplifier

Types of professionalization: understanding contemporary organizational designs of Swiss national sport federations

Purpose – The purpose of this paper is to identify types of professionalization in Swiss national sport federations (NSFs) and analyze organizational characteristics associated with specific types of professionalization. Such types reveal common patterns among the increasingly complex organizational designs of NSFs and thus contribute to the understanding of professionalization in NSFs. Design/methodology/approach – An online survey of all Swiss NSFs was conducted to identify types of professionalization in these organizations using hierarchical cluster analysis, based on a multi-dimensional framework of professionalization. Findings – The analysis revealed four types of professionalization: formalized NSFs managed by paid staff, NSFs managed by volunteers and a few paid staff off the field, NSFs with differing formalization and paid staff on the field, and moderately formalized NSFs managed by volunteers. The types differ in terms of the NSFs’ organizational characteristics, in particular, size, financial resources, Olympic status, and performance. Originality/value – Applying factor and cluster analysis is a new approach to analyzing professionalization in NSFs that makes uncovering distinctive organizational patterns among a large number of NSFs possible. These results lay the foundation for understanding the professionalization of NSFs, counseling NSFs on their organizational development, and conducting future research on the design types of sport organizations

Countrywide campaign to prevent soccer injuries in Swiss amateur players.

Background: In Switzerland, the national accident insurance company registered a total of 42 262 soccer injuries, resulting in costs of approximately 145 million Swiss francs (~US$130 million) in 2003. Research on injury prevention has shown that exercise-based programs can reduce the incidence of soccer injuries

Countrywide campaign to prevent soccer injuries in Swiss amateur players.

Background: In Switzerland, the national accident insurance company registered a total of 42 262 soccer injuries, resulting in costs of approximately 145 million Swiss francs (~US$130 million) in 2003. Research on injury prevention has shown that exercise-based programs can reduce the incidence of soccer injuries