Subset sum problems with digraph constraints

We introduce and study optimization problems which are related to the well-known Subset Sum problem. In each new problem, a node-weighted digraph is given and one has to select a subset of vertices whose total weight does not exceed a given budget. Some additional constraints called digraph constraints and maximality need to be satisfied. The digraph constraint imposes that a node must belong to the solution if at least one of its predecessors is in the solution. An alternative of this constraint says that a node must belong to the solution if all its predecessors are in the solution. The maximality constraint ensures that no superset of a feasible solution is also feasible. The combination of these constraints provides four problems. We study their complexity and present some approximation results according to the type of input digraph, such as directed acyclic graphs and oriented trees.     

Divorce and parity progression following the death of a child: A register-based study from Finland

Most studies that have examined whether a child’s death influences parental relationship stability have used small-scale data sets and their results are inconclusive. A likely reason is that child loss affects not only the risk of parental separation, but also the risk of having another child. Hence parity progression and separation must be treated as two competing events in relation to child loss. The analysis in this paper used Finnish register data from 1971 to 2003, covering over 100,000 married couples whose durations of both first marriage and parenthood could be observed. We ran parity-specific Cox regressions in which process time started from the birth of each additional child. All marriages included women of childbearing age, none of whom had experienced any child death on entering the analysis. We find that child loss only modestly influences the divorce risk, whereas its effect on the risk of parity progression is considerable.     

Initiative in work teams: adaptation and validation of the Personal Initiative at Group Level Scale / Iniciativa en los equipos de trabajo: adaptación y validación de la Escala de Iniciativa Personal a nivel Grupal

In this study, we conceptualize personal initiative as a collective construct and adapt and validate a scale to evaluate it with a sample of 308 Spanish participants belonging to 91 work teams. Personal initiative at group level is a behavioural syndrome in which the team shows an approach to work that is self-initiated, proactive, persistent, capable of modifying the atmosphere and pro organization. As a predictive variable, we analysed the climate for initiative as well as personal initiative at group level. The resulting variables that were analysed referred to organization and team performance, with the team productivity and innovation as the criteria, analysing radical innovation. The scale has suitable psychometric properties. The results show that there is a relationship between the two predictive variables. Furthermore, personal initiative at group level is related to team productivity, while the climate for initiative is related to innovation.     

‘What Was I Thinking?!’ Rhetorical Questions as a Technique to Identify and Explore Impasses in Therapy

Rhetorical questions emerging spontaneously in consultations can be used as a tool for developing self‐reflexivity and exploring the therapeutic alliance in the process of therapy with couples and families. This paper presents a technique based on the enunciation of rhetorical questions, which can point to an impasse in the process of therapy and contain a key to its resolution. The technique focuses on the distinctive feature of rhetorical questions as convening a paradoxical injunction: a question not intended as a question, while uttered as such. The technique in four steps is illustrated by examples from therapy, supervision, consultation, and self‐supervision. Its focus is the interlink between the therapeutic relationship and the process of therapy and it is informed by a second‐order cybernetics approach, dialogical practice, and the systemic literature on emotion. The technique can help develop curiosity in working with families, lead to unforeseen developments, and touch on prejudices not made explicit in previous therapeutic encounters. Whether we are acting as supervisors, therapists, or clients, the creation of a ‘secure enough’ context for rhetorical questions becomes critical to allow freeform exploration.     

Ventriloquism,racism and the politics of decoloniality in Ecuador

ABSTRACT

This article discusses two forms of discrimination against indigenous people: ventriloquism and open racism, and argues that a transition from paternalism to open intolerance has taken place in Ecuador in the context of governmental emphasis on natural resource extraction. Ventriloquism, when non-Indians speak for indigenous people, is analysed through the Sumak Kawsay (Good Living) policies of the government of Rafael Correa (2007–2017). Public racism is examined by looking at government repression against indigenous leaders and communities and Presidential speeches. The article concludes that the state’s ventriloquist and racist discourses and practices are equally rooted in the country’s colonial past. These findings are contrasted with the writings of scholars that have called the government of Mr. Correa decolonizing. The article examines the ways in which decolonial theorists informed and promoted the policies of this regime, and argues that decolonial scholars have been insufficiently self-critical and reflective of their own complicity with the state’s repressive project vis-à-vis indigenous communities.     

A copula-based Markov chain model for the analysis of binary longitudinal data

A fully parametric first-order autoregressive (AR(1)) model is proposed to analyse binary longitudinal data. By using a discretized version of a copula, the modelling approach allows one to construct separate models for the marginal response and for the dependence between adjacent responses. In particular, the transition model that is focused on discretizes the Gaussian copula in such a way that the marginal is a Bernoulli distribution. A probit link is used to take into account concomitant information in the behaviour of the underlying marginal distribution. Fixed and time-varying covariates can be included in the model. The method is simple and is a natural extension of the AR(1) model for Gaussian series. Since the approach put forward is likelihood-based, it allows interpretations and inferences to be made that are not possible with semi-parametric approaches such as those based on generalized estimating equations. Data from a study designed to reduce the exposure of children to the sun are used to illustrate the methods.     

Bayesian robustness of the compound Poisson distribution under bidimensional prior: an application to the collective risk model

The distribution of the aggregate claims in one year plays an important role in Actuarial Statistics for computing, for example, insurance premiums when both the number and size of the claims must be implemented into the model. When the number of claims follows a Poisson distribution the aggregated distribution is called the compound Poisson distribution. In this article we assume that the claim size follows an exponential distribution and later we make an extensive study of this model by assuming a bidimensional prior distribution for the parameters of the Poisson and exponential distribution with marginal gamma. This study carries us to obtain expressions for net premiums, marginal and posterior distributions in terms of some well-known special functions used in statistics. Later, a Bayesian robustness study of this model is made. Bayesian robustness on bidimensional models was deeply treated in the 1990s, producing numerous results, but few applications dealing with this problem can be found in the literature.     

Living a Deportation Threat: Anticipatory Stressors Confronted by Undocumented Mexican Immigrant Women

Previous sociological research shows that exposure to stress varies by individuals’ social statuses and is a central mechanism in producing mental health disparities. This line of research suggests that ethnoracial groups are more exposed to racial discrimination, thus negatively impacting their mental health. There has also been a growing literature showing how legal status impacts the mental health of immigrants and their families. However, the sociology of mental health and migration literature has largely remained disparate. This paper bridges these literatures to highlight how living a deportation threat manifests itself as an anticipatory stressor that negatively impacts undocumented Mexican migrant women’s access to resources, social relationships, and social roles. Based on 30 semi-structured in-depth interviews with undocumented Mexican immigrant women from Houston, Texas, my findings reveal living a deportation threat is a perpetual anticipatory stressor that intensifies the effects of avoiding authorities, family fragmentation, and economic uncertainty. I argue this anticipatory stressor transforms into a chronic stressor that undocumented Mexican women confront daily. By situating this study within an anti-immigrant social context, it highlights the social processes and mechanisms that exacerbate the stressors undocumented Mexican immigrant women confront.