Probability of Low‐Altitude Midair Collision Between General Aviation and Unmanned Aircraft

Unmanned aircrafts (UA) usually fly below 500 ft to be segregated from manned aircraft. However, while general aviation (GA) usually do fly above 500 ft in areas where UA are allowed to operate, GA will at times also fly below 500 ft. Consequently, there is a distinct risk of near‐miss encounters as well as actual midair collisions (MACs). This work presents a model for determining this risk based on physical parameters of the aircraft and actual figures for the numbers of GA in a given airspace, as well as the probability of having GA below 500 ft. The aim is to achieve a prediction with a precision better than one order of magnitude relative to the true MAC rate value. The model is applied to Danish airspace and the MAC rate for unmitigated operations of UA is found to be approximately 10^?6 MAC per flight hour. The model is particularly well suited for beyond visual line‐of‐sight operations, and is useful for UA operators for conducting risk assessment of planned operations as well as for regulators for determining appropriate operational requirements.     

Institutionalized Ignorance as a Precondition for Rational Risk Expertise

The present case study seeks to explain the conditions for experts’ rational risk perception by analyzing the institutional contexts that constitute a field of food safety expertise in Denmark. The study highlights the role of risk reporting and how contextual factors affect risk reporting from the lowest organizational level, where concrete risks occur, to the highest organizational level, where the body of professional risk expertise is situated. The article emphasizes the role of knowledge, responsibility, loyalty, and trust as risk‐attenuation factors and concludes by suggesting that the preconditions for the expert's rationality may rather be a lack of risk‐specific knowledge due to poor risk reporting than a superior level of risk knowledge.     

Migration, Return, and Development: An Institutional Perspective

The development community has been rather reluctant in the past to integrate migration as a parameter for development policies, as often advocated by politicians and the migration community. The following analysis demonstrates that the position of development institutions on this matter has evolved, e.g., in the direction of increased interest among development practitioners to look at remittances as a tool for development. The article discusses the importance of brain drain and possibilities for using return migration as a brain gain. It introduces the concept "migration band" as an aggregate expression of Martin's "migration hump" for individual countries. Furthermore, it suggests policy options for a foreign input policy mix to developing countries composed of foreign direct investment, trade liberalizations, aid, remittances, return migration, and improved governance.     

Discourse ethics in TA procedures: a game theory model

This article argues that an ethic applying the technology assessment (TA)-method is only feasible as a risk ethic, since the consequences of technical action are ambivalent and uncertain. It first distinguishes possible strategies of justification for a risk ethic, that is (a) deontological, (b) teleological and (c) procedural approaches. On the basis of the critique of both (a) and (b), a central problem for the integration of discourse ethics in the TA-method is highlighted by reverting to a game theory modeling: As it turns out, mechanisms of self-selection undermine the representativity of discourses and thus its legitimation. In view of this dilemma, the article pledges for a complementary approach selectively integrating (a)–(c) into a “provisional moral”.     

Perception of own death risk

Individuals’ perception of their own road-traffic and overall mortality risks are examined in this paper. Perceived risk is compared with the objective risk of the respondents’ peers, i.e. their own gender and age group, and the results suggest that individuals’ risk perception of their own risk is biased. For road-traffic risk we obtain similar results to what have been found previously in the literature, overassessment and underassessment among low- and high-risk groups, respectively. For overall risk we find that all risk groups underestimate their risk. The results also indicate that men's risk bias is larger than women’s.

Client contribution in negotiations on employability – categories revised?

Eskelinen L, Olesen SP, Caswell D. Client contribution in negotiations on employability – categories revised? Int J Soc Welfare 2010: 19: 330–338 © 2010 The Author(s), Journal compilation © 2010 Blackwell Publishing Ltd and International Journal of Social Welfare. In this article, we explore how the institutional category ‘unemployed’ is specified in everyday practice when implementing an active employment policy. We illustrate the process of categorisation as an aspect of the in situ positioning and self‐representation of the client by examining one social worker–client talk: how the category unemployed is shaped and ‘translated’ when the client negotiates her situation with the social worker. Two types of category revisions are identified. First, the employability of the client, rather than her unemployment situation, is the issue under negotiation. Second, the client introduces new categories that are compatible with the demands of the employment system. She contributes by drawing on discursive resources related to the category of ‘active job seeker’ but does this with an own agenda of looking for a suitable job. The analysis elucidates the client's contribution to institutional practice and discusses constitutive and constituted elements of categorisation.     

Problematic Bodies: Past,Present, and Future

Good Days, Bad Days: The Self in Chronic Illness and Time , by Kathy Charmaz. At The Will of The Body: Reflections on Illness , by Arthur W. Frank. The Body: Social Process and Cultural Theory , edited by Mike Featherstone, Mike Hepworth, and Bryan S. Turner.     

Structure Learning of Contextual Markov Networks using Marginal Pseudo‐likelihood

Markov networks are popular models for discrete multivariate systems where the dependence structure of the variables is specified by an undirected graph. To allow for more expressive dependence structures, several generalizations of Markov networks have been proposed. Here, we consider the class of contextual Markov networks which takes into account possible context‐specific independences among pairs of variables. Structure learning of contextual Markov networks is very challenging due to the extremely large number of possible structures. One of the main challenges has been to design a score, by which a structure can be assessed in terms of model fit related to complexity, without assuming chordality. Here, we introduce the marginal pseudo‐likelihood as an analytically tractable criterion for general contextual Markov networks. Our criterion is shown to yield a consistent structure estimator. Experiments demonstrate the favourable properties of our method in terms of predictive accuracy of the inferred models.