Strong convergence rates of probabilistic integrators for ordinary differential equations

Probabilistic integration of a continuous dynamical system is a way of systematically introducing discretisation error, at scales no larger than errors introduced by standard numerical discretisation, in order to enable thorough exploration of possible responses of the system to inputs. It is thus a potentially useful approach in a number of applications such as forward uncertainty quantification, inverse problems, and data assimilation. We extend the convergence analysis of probabilistic integrators for deterministic ordinary differential equations, as proposed by Conrad et al. (Stat Comput 27(4):1065–1082, 2017. https://doi.org/10.1007/s11222-016-9671-0), to establish mean-square convergence in the uniform norm on discrete- or continuous-time solutions under relaxed regularity assumptions on the driving vector fields and their induced flows. Specifically, we show that randomised high-order integrators for globally Lipschitz flows and randomised Euler integrators for dissipative vector fields with polynomially bounded local Lipschitz constants all have the same mean-square convergence rate as their deterministic counterparts, provided that the variance of the integration noise is not of higher order than the corresponding deterministic integrator. These and similar results are proven for probabilistic integrators where the random perturbations may be state-dependent, non-Gaussian, or non-centred random variables.

     

When the Norwegian child-welfare services get involved: parents making sense of referrals

There is limited research exploring parents' views and understanding of referrals to the child-welfare services (CWS). This study explores parents' understanding of the circumstances leading to a child-welfare referral, and their understanding of the reporter's objectives in making the referral. Qualitative content analysis and frequency analysis was performed on open-ended survey responses from a sample of 683 Norwegian parents in contact with the CWS. The results showed that the majority (60.2%) of the parents perceived the referral to be initiated solely because of parental difficulties and multiple family life stressors. Some of the parents (22.8%) believed the referrals were initiated exclusively because of their children's problems, whereas a few (13.3%) perceived it to be a combination of parental/familial difficulties and children's problems. The findings reveal that close to half of the parents (46.4%) felt the objective of the person making the referral was to help the child, their parents and the family. Some (36.5%) saw it as a routine or mandated action by public or official services, while others (18.7%) reported that they did not know why referrals had been made, or gave no answer to the question. A small group of parents (6%) viewed the referral as an act of harassment. The main implications of these findings are discussed.     

Sequential Monte Carlo for rare event estimation

This paper discusses a novel strategy for simulating rare events and an associated Monte Carlo estimation of tail probabilities. Our method uses a system of interacting particles and exploits a Feynman-Kac representation of that system to analyze their fluctuations. Our precise analysis of the variance of a standard multilevel splitting algorithm reveals an opportunity for improvement. This leads to a novel method that relies on adaptive levels and produces, in the limit of an idealized version of the algorithm, estimates with optimal variance. The motivation for this theoretical work comes from problems occurring in watermarking and fingerprinting of digital contents, which represents a new field of applications of rare event simulation techniques. Some numerical results show performance close to the idealized version of our technique for these practical applications.     

Mobility and Professional Networks in Academia: An Exploration of the Obligations of Presence

This article explores the obligations of presence behind work-related mobility for academics in internationalizing higher education systems. By further developing John Urry’s concept of ‘meetingness’, the article reveals how academics depend on corporeal and virtual mobility to create and maintain a networked professional life outside their own institution, which is crucial in the context of changing work conditions. Our insights are drawn from original qualitative research (42 interviews) in a Flemish and Danish context. The data reveal obligations of presence associated with an interrelated mix of functionality, and the construction of dense and sparse social networks that together support career success and work at the frontiers of academic knowledge. Despite the now well-recognized costs of corporeal mobility, obligations of presence result in virtual and corporeal mobility coexisting, rather than the former substituting for the latter. Virtual mobility is mainly used when conflicting obligations of presence exist, and as a means of sustaining networks over time given the processual nature of meetingness, rather than as a means to reduce levels of corporeal mobility.     

Bioaccessibility and Risk of Exposure to Metals and SVOCs in Artificial Turf Field Fill Materials and Fibers

To reduce maintenance costs, municipalities and schools are starting to replace natural grass fields with a new generation synthetic turf. Unlike Astro‐Turf, which was first introduced in the 1960s, synthetic field turf provides more cushioning to athletes. Part of this cushioning comes from materials like crumb rubber infill, which is manufactured from recycled tires and may contain a variety of chemicals. The goal of this study was to evaluate potential exposures from playing on artificial turf fields and associated risks to trace metals, semi‐volatile organic compounds (SVOCs), and polycyclic aromatic hydrocarbons (PAHs) by examining typical artificial turf fibers (n = 8), different types of infill (n = 8), and samples from actual fields (n = 7). Three artificial biofluids were prepared, which included: lung, sweat, and digestive fluids. Artificial biofluids were hypothesized to yield a more representative estimation of dose than the levels obtained from total extraction methods. PAHs were routinely below the limit of detection across all three biofluids, precluding completion of a meaningful risk assessment. No SVOCs were identified at quantifiable levels in any extracts based on a match of their mass spectrum to compounds that are regulated in soil. The metals were measurable but at concentrations for which human health risk was estimated to be low. The study demonstrated that for the products and fields we tested, exposure to infill and artificial turf was generally considered de minimus, with the possible exception of lead for some fields and materials.     

Who Gets Custody Now? Dramatic Changes in Children’s Living Arrangements After Divorce

This article reexamines the living arrangements of children following their parents’ divorce, using Wisconsin Court Records, updating an analysis that showed relatively small but significant increases in shared custody in the late 1980s and early 1990s. These changes have accelerated markedly in the intervening years: between 1988 and 2008, the proportion of mothers granted sole physical custody fell substantially, the proportion of parents sharing custody increased dramatically, and father–sole custody remained relatively stable. We explore changes in the correlates of alternative custody outcomes, showing that some results from the earlier analysis still hold (for example, cases with higher total family income are more likely to have shared custody), but other differences have lessened (shared-custody cases have become less distinctive as they have become more common). Despite the considerable changes in marriage and divorce patterns over this period, we do not find strong evidence that the changes in custody are related to changes in the characteristics of families experiencing a divorce; rather, changes in custody may be the result of changes in social norms and the process by which custody is determined.     

Unruly Voices in the Museum

ABSTRACT

This article addresses the use of audio recordings and oral memory for the critical engagement with colonial pasts in ethnographic museums by focusing on the traveling exhibition What We See, curated by Anette Hoffmann (2009). Specifically, it draws on Jeffrey Feldman's notion of colonial “contact points,” i.e. material traces of colonial encounter, to highlight the exhibition's ability to convey and critique the sensory experience of colonial contact. In What We See, this colonial contact consisted in an anthropometric project conducted in South-West Africa, today's Namibia, in 1931, resulting in an archive of anthropometric measurements and photographs, life-casts, and phonographic recordings. The exhibition proposed an innovative way of reworking this archive by staging an intricate interplay between sound and sight, thereby disrupting conventional ocularcentric forms of display. However, this multisensory approach provoked highly divergent reactions at its various exhibition venues. This article argues that the divergent reactions in Cape Town, South Africa, and Vienna, Austria, were due to different levels of what Ann Stoler describes as “colonial aphasia”—that is the context-dependent difficulty of addressing disquieting colonial pasts and its sensory dimensions.     

‘Notorious Beyond Any Other European Woman of Her Generation’: The Case of Count(ess) Sarolta/Sándor Vay

The paper investigates the curious case of the Hungarian Count(ess) Sarolta/Sándor Vay, journalist and writer, but, above all, a notorious gender bender in late nineteenth-century Austro-Hungarian Monarchy. The article examines her case in the context of the history of European cross-dressing and of narrative transvestism. The author argues that nineteenth-century dandyism provided an effective cultural framework for Vay’s contemporaries to accept her unconventional presence in fin-de-siècle Hungarian society. Moreover, she claims that Vay’s narrative transvestism may also be construed within the cultural phenomenon of dandyism, as her writing practices prove to be further instruments for her self-fashioning. Finally, she concludes that Vay’s gender performance and narrative transvestism become illustrative examples of instances that both frame and confuse accepted cultural patterns, destabilize gender binarism, and participate in its maintenance.     

Perceived emotional intelligence and social competence in neglected adolescents

This research work analyses the emotional intelligence (EI) and the social cognitive attitudes and strategies in adolescents between 12 and 17 years of age in residential care. The aim of the work is to identify those aspects that hinder their socio-emotional competence, requiring a more urgent intervention. We explore the presence of significant differences between the variables under study according to gender and age range (12–14 and 15–17) and we analyse the relationship between the dimensions of their EI and their social competence. The results show a lack of EI in these adolescents, with all three dimensions being affected: emotional attention, clarity of feelings and emotional repair. As for social competence, it can be seen that the adolescents are characterised by a lack of confidence and firmness in their interactions. Worthy of note is the impulsive cognitive style, as are the rigidity of thought and the tendency towards social mistrust and suspicion. There are many difficulties concerning the strategies for resolving social problems. This research highlights the need to design training programmes for the residential care centres that will favour their socio-emotional development.