On the convergence of two sequential Monte Carlo methods for maximum a posteriori sequence estimation and stochastic global optimization

This paper addresses the problem of maximum a posteriori (MAP) sequence estimation in general state-space models. We consider two algorithms based on the sequential Monte Carlo (SMC) methodology (also known as particle filtering). We prove that they produce approximations of the MAP estimator and that they converge almost surely. We also derive a lower bound for the number of particles that are needed to achieve a given approximation accuracy. In the last part of the paper, we investigate the application of particle filtering and MAP estimation to the global optimization of a class of (possibly non-convex and possibly non-differentiable) cost functions. In particular, we show how to convert the cost-minimization problem into one of MAP sequence estimation for a state-space model that is “matched” to the cost of interest. We provide examples that illustrate the application of the methodology as well as numerical results.     

The Effect of Sensorimotor Training on the Postural Stability of Visually Impaired Women Over 50 Years of Age

Previous studies indicated that blind and visually impaired people are a group with greater risk of falls. Postmenopausal changes significantly decrease physical efficiency and impair the body’s mechanisms for maintaining postural stability. In addition, the frequency of falls among women is much higher than in men. The aim of this study was to analyze the effect of sensorimotor exercise on changes in postural stability of visually impaired women over 50 years of age. Visually impaired women from group E showed a lower level of postural stability measured with EO compared to the healthy women. After completing the exercise, a more pronounced improvement in the level of postural stability was observed in group E.     

Futurelessness,migration, or a lucky break: narrative tropes of the ‘blocked future’ among Serbian high school students

ABSTRACT

This article uses ethnographic discourse analysis to understand how Serbian high school students at ‘Belgrade Professional’ (BP) respond to coursework and discussions about their individual futures. Contextualizing the conversations at BP within broader local and international social forces, the paper shows how students’ perceptions of their future chances are mediated by both the school’s outdated promises of secure skilled employment and a broad understanding of Western liberal democracies as ‘meritocratic’. In short, I argue that BP students recognize the elective ‘choice biography’ as a real pathway to adulthood. However, they primarily imagine the choice biography as existing outside of Serbia, while feeling constrained by – even hostile to – such an idea within the country. To counter choice biography framings of futures in Serbia, students mobilize a discourse I call the ‘blocked future’, comprised of three related narrative tropes informed by the decades-long recession: domestic futurelessness, meritocracy abroad, and local chance. These narrative tropes illuminate the emerging cultural structures in Serbia which reflect how people cope with and processes the conflicting structural demands and unfulfilled promises of the post-socialist transition in everyday life.     

What’s off-centre of empire? Introduction to the special issue

ABSTRACT

In this Introduction, we discuss the aims of this publication along with guidelines to locate and connect the essays part of the edited volume. We start by highlighting the original contribution of our intervention in terms of what off-centring empire offers in relation to scholarship that de-centres empire. To us, this means to look at the processes, dynamics, and movements that connect empire (as a centre of power) to its peripheries (as a site of difference, struggles, and resistance). To be sure, attempts to off-centre and de-centre empire are related, relational, and they both commit to the project of challenging the centrality of empire, to confronting its lasting legacies and normative powers. Yet to off-centre, as we argue, is to focus on the electrifying force-field generated by the poles of imperial power, rather than oppose centre and peripheries to subvert their relationship. Our aim is to reveal the complex ways centre and periphery connect and distance with the aim to highlight emerging modes of counter-imperial practice. Further, this introduction serves as the opportunity to discuss the structure of the SI and its three main sections – Public Memory, Orientations, and More-than-human. Here we reflect upon how each essay brings to the fore a unique way to off-centre empire, and thus provide examples that may inspire future research. Finally, we highlight how conversations emerging from individual essays can be assembled and read into threads, pointing to multiple ways in which we seek to off-centre empire through empirical research.     

The workplace perspective on supporting family caregivers at end of life: evaluating a new Canadian social program

There is a growing realization that employers need to accommodate the issue of work-life balance for employees who are also providing care for family members or friends in palliative or end-of-life situations, as this phenomenon is only expected to increase within developed nations in the future given demographic trends and health care restructuring. This research aims to uncover the expectations that Canadian employers/human resources (HR) professionals have of the Compassionate Care Benefit (CCB), in addition to their experienced realities of having staff utilize this social program. The CCB provides employed family/informal caregivers with a job-secured work leave and six weeks of employment insurance benefits while they take time off to provide care to a dying family member or close other, often at home (in the community). Five focused discussions were implemented with employers/HR across Canada. Using thematic analysis, the data reveal how well (or not) the CCB meets caregivers' needs, as well as the informational and procedural needs of workplaces. In light of these findings, suggestions for program improvement, with respect to the CCB, are made in order to advocate for continued support of family/informal caregivers whose voices are rarely heard.     

Limiting distribution of the number of clumps of palindromes in DNA

An important aspect in the analysis of long DNA sequences is to identify whether palindromes are over- or under-represented. The essential step in that direction is the analysis of the limiting distribution of the number of clumps of palindromes where clump is defined as the overlapping occurrence of palindromes. Using the Chen–Stein method, it is shown in this paper that the limiting distribution, under suitable conditions and a type of heterogeneous sequence, is the Poisson distribution. Moreover, error bounds and the rate of convergence are derived in terms of total variation distance between two probability distributions.     

On the radius of centrality in evolving communication networks

In this article, we investigate how the choice of the attenuation factor in an extended version of Katz centrality influences the centrality of the nodes in evolving communication networks. For given snapshots of a network, observed over a period of time, recently developed communicability indices aim to identify the best broadcasters and listeners (receivers) in the network. Here we explore the attenuation factor constraint, in relation to the spectral radius (the largest eigenvalue) of the network at any point in time and its computation in the case of large networks. We compare three different communicability measures: standard, exponential, and relaxed (where the spectral radius bound on the attenuation factor is relaxed and the adjacency matrix is normalised, in order to maintain the convergence of the measure). Furthermore, using a vitality-based measure of both standard and relaxed communicability indices, we look at the ways of establishing the most important individuals for broadcasting and receiving of messages related to community bridging roles. We compare those measures with the scores produced by an iterative version of the PageRank algorithm and illustrate our findings with three examples of real-life evolving networks: the MIT reality mining data set, consisting of daily communications between 106 individuals over the period of 1 year, a UK Twitter mentions network, constructed from the direct tweets between \(12.4\) k individuals during 1 week, and a subset of the Enron email data set.