New combinatorial structures with applications to efficient group testing with inhibitors

Group testing with inhibitors (GTI) is a variant of classical group testing where in addition to positive items and negative items, there is a third class of items called inhibitors. In this model the response to a test is YES if and only if the tested group of items contains at least one positive item and no inhibitor. This model of group testing has been introduced by Farach et al. (Proceedings of compression and complexity of sequences, pp 357–367, 1997) for applications in the field of molecular biology. In this paper we investigate the GTI problem both in the case when the exact number of positive items is given, and in the case when the number of positives is not given but we are provided with an upper bound on it. For the latter case, we present a lower bound on the number of tests required to determine the positive items in a completely nonadaptive fashion. Also under the same hypothesis, we derive an improved lower bound on the number of tests required by any algorithm (using any number of stages) for the GTI problem. As far as it concerns the case when the exact number of positives is known, we give an efficient trivial two-stage algorithm. Instrumental to our results are new combinatorial structures introduced in this paper. In particular we introduce generalized versions of the well known superimposed codes (Du, D.Z., Hwang, F.K. in Pooling designs and nonadaptive group testing, 2006; Dyachkov, A.G., Rykov, V.V. in Probl. Control Inf. Theory 12:7–13, 1983; Dyachkov, A.G., et al. in J. Comb. Theory Ser. A 99:195–218, 2002; Kautz, W.H., Singleton, R.R. in IEEE Trans. Inf. Theory 10:363–377, 1964) and selectors (Clementi, A.E.F, et al. in Proceedings of symposium on discrete algorithms, pp. 709–718, 2001; De Bonis, A., et al. in SIAM J Comput. 34(5):1253–1270, 2005; Indyk, P. in Proceedings of symposium on discrete algorithms, pp. 697–704, 2002) that we believe to be of independent interest.     

Self-enforcing family rules,marriage and the (non)neutrality of public intervention

We demonstrate that the notion of a family ‘constitution’ (self-enforcing, renegotiation-proof norm) requiring adults to provide attention for their elderly parents carries over from a world where identical individuals reproduce asexually, to one where individuals differentiated by sex and preferences marry, have children and bargain over the allocation of domestic resources. In this heterogenous world, couples are sorted by their preferences. If a couple’s common preferences satisfy a certain condition, the couple have an interest in instilling those preferences into their children. Policies are generally nonneutral. In particular, wage redistribution may raise, and compulsory education will reduce, the share of the adult population that is governed by family constitutions, and thus the share of the elderly population who receive attention from their children.     

From Talk to Action: Experiencing Interlocution in Developmental Interventions

This article explores how to analyze and conceptualize the dynamics through which conversations in Change Laboratory research interventions lead to envisioning and implementing material changes in activities. Leont'ev's concept of personal sense is used as a theoretical lens for tracing these dynamics and to provide a means to relate local conversations to overall transformation of professional practices. In addition, the article tests the potential of Vasilyuk's theory of experiencing and Trognon's interlocutionary logic for analyzing Change Laboratory conversations from the point of view of how talk is experienced by the interlocutors. Experiencing is seen as a dialogical process that connects ongoing conversations and future-oriented actions, and through which interlocutors overcome critical situations. The analysis of Change Laboratory discussions in a Finnish middle school provides ground for looking at Change Laboratory as a research setting and a practice of intervention which can enrich our understanding of how change unfolds through discourse. The article concludes that interventions such as Change Laboratory could benefit from identifying systematic procedures for facilitating experiencing and interlocution. Within the perspective of seeking such methodological procedures, the article opens up a discussion on complementarities and possibilities of integration between the Change Laboratory and another interventionist approach called the Clinic of Activity.     

Fathers' Stories of Resistance and Hegemony in Organizational Cultures

This article focuses on the practices of resistance and hegemony that oppose change in gender cultures in organizations. It suggests that analysis of the narratives produced by organizational actors is a fruitful method with which to deal with issues of this kind. In particular, the analysis concentrates on how resistance and hegemony practices may affect the implementation of changes promoted at a normative level — as in the case of the Italian law that has extended the right to take parental leave for childcare to men as well, in opposition to the dominant cultural models of gender. The analysis of the experiences reported by men belonging to different organizations, and having in common the use of parental leave to spend time with their children, allows us to reflect upon the fact that the symbolic orders of gender in organizations cannot be challenged at a normative level if the change does not affect the organizational culture, becoming embedded in everyday organizational practices.     

COVID‐19 as a breakdown in the texture of social practices

‘A lot of things need to be repaired and a lot of relationships are in need of a knowledgeable mending. Can we start to talk/write about them?’ This invitation — sent by one of the authors to the others — led us, as feminist women in academia, to join together in an experimental writing about the effects of COVID‐19 on daily social practices and on potential (and innovative) ways for repairing work in different fields of social organization. By diffractively intertwining our embodied experiences of becoming together‐with Others, we foreground a multiplicity of repair (care) practices COVID‐19 is making visible. Echoing one another, we take a stand and say that we need to prevent the future from becoming the past. We are not going back to the past; our society has already changed and there is a need to cope with innovation and repairing practices that do not reproduce the past.     

Toward a Grammar of Collaboration

Inspired by Susan Leigh Star’s work, we propose a conceptual grammar for analyzing and comparing culturally and historically different kinds of collaboration. Drawing on cultural-historical activity theory and Bakhtin’s theorizing, the grammar is tested and concretized with the help of the macroscale case of different types of social movements and the microscale case of different types of collaboration in home care encounters. There is no direct mapping across these scales, but the conceptual lens seems to work at both. This is seen as a first step toward a grammar of collaboration that allows some continuity of movement across the levels.     

How to make good choices? Ethical perspectives guiding social workers moral reasoning

Framing and distinguishing mainstream social work ethical perspectives could be useful for social work students and practitioners facing moral choices in daily practice. The article presents a summary and classification of a range of ethical theories and provides some insights into the relationship between ethical thinking and practice issues. It distinguishes between classical approaches and ‘situated’ positions. The former – which includes teleological, deontological, and rights-based approaches – refer to universal and general principles. ‘Situated’ ethics are linked to specific and unique situations of professional practice. Finally, the article suggests some useful questions derived from each approach in order to help students to reflect on complex ethical choices occurring in daily practice.     

Measures of Optimal Centrality: Indicators of City Effect and Urban Overloading

'City-effect' is the peculiar quality of large urban settlements enjoyed by their residents and users. It involves a direct access to special ('superior') urban functions, opportunities and services. This is why it is a very much sought after object of individual and collective aspirations. Large cities concentrate city-effect and often act as powerful magnets in attracting commuters and new residents from surrounding areas, where city-effect is weaker. But when concentration goes beyond a certain threshold, overburdened cities pay for their city-effect in terms of decreasing liveability. Searching for optimal centrality, that is an acceptable trade-off between city effect and decreasing liveability, is among the aims of territorial planning. This paper illustrates a research on the measures of optimal centrality, where social indicators play a key methodological role. It was jointly carried out in four European countries. The indicator-building process is described, and a few points resulting from the study on the operational prerequisites for harmonising and standardising the proposed measures for territorial policies are also offered for reflection.     

Breaking the Stability Pact: Was it predictable?

We show analytically that the credibility problem which has affected the European Stability Pact originates from the insufficient distinction between two reasons for having binding fiscal constraints. The first reason deals with the governments’ tendency to neglect the effects of their fiscal policy on foreign governments (fiscal free-riding). The second reason follows from the governments’ tendency to raise debt by lowering taxes or increasing expenditures, and then to leave it to their successors (fiscal short-termism). An enforcement mechanism relying on governments’ collusion works if the fiscal constraints are not calibrated for curing fiscal short-termism but only for preventing fiscal free-riding.     

A normative justification of compulsory education

Using a household production model of educational choices, we characterise a free-market situation in which some agents (high wagers) fully educate their children and spend a sizable amount of resources on them, while others (low wagers) educate them only partially. The free-market equilibrium is iniquitous, both because the households have different resources and because the children have different access to education. Public policy is thus called for, for vertical as well as horizontal equity purposes. Conventional wisdom has it that both objectives could be achieved using price control instruments, i.e. income taxes and price subsidies. We find instead that income taxes reduce equality of opportunity and that price subsidies cannot remedy this. Quantity controls become necessary: a compulsory education package, financed by a redistributive tax system, achieves both types of equity. Redistributive taxation and compulsory education are therefore best seen as complementary policies.