Analysing the interevent time distribution to identify seismicity phases: a Bayesian nonparametric approach to the multiple-changepoint problem

In the study of earthquakes, several aspects of the underlying physical process, such as the time non-stationarity of the process, are not yet well understood, because we lack clear indications about its evolution in time. Taking as our point of departure the theory that the seismic process evolves in phases with different activity patterns, we have attempted to identify these phases through the variations in the interevent time probability distribution within the framework of the multiple-changepoint problem. In a nonparametric Bayesian setting, the distribution under examination has been considered a random realization from a mixture of Dirichlet processes, the parameter of which is proportional to a generalized gamma distribution. In this way we could avoid making precise assumptions about the functional form of the distribution. The number and location in time of the phases are unknown and are estimated at the same time as the interevent time distributions. We have analysed the sequence of main shocks that occurred in Irpinia, a particularly active area in southern Italy: the method consistently identifies changepoints at times when strong stress releases were recorded. The estimation problem can be solved by stochastic simulation methods based on Markov chains, the implementation of which is improved, in this case, by the good analytical properties of the Dirichlet process.     

A note on testing for nonstationarity in autoregressive processes with level dependent conditional heteroskedasticity

In this paper, we investigate the empirical distribution and the statistical properties of maximum likelihood (ML) unit-root t-statistics computed from data sampled from a first-order autoregressive (AR) process with level-dependent conditional heteroskedasticity (LDCH). This issue is of particular importance for applications on interest rate time-series. Unfortunately, the extent of the technical complexity related associated to LDCH patterns does not offer a feasible theoretical analysis, and there is no formal knowledge about the finite-sample size and power behaviour or the ML test for this context. Our analysis provides valuable guidelines for applied work and directions for future work.     

Pruning regression trees for censored survival data: the recpam approach

RECPAM is a methodology, implemented in a computer program of the same name, for the construction of tree-structured models in Biostatistics. In this work we present algorithms for pruning and amalgamating terminal nodes of a tree, within the RECPAM approach. These algorithms construct sequences of nested models and calculate at each step the AIC of the corresponding model and correct significance levels, according to Gabriel's theory of Simultaneous Test Procedures. As an example, the analysis of data from clinical trials involving patients with Small Cell Carcinoma of the Lung is presented.     

The majority rule with a chairman

For the case of two alternatives and a given finite set of at least three individuals, seven axioms are shown to characterize the rules that are either the relative majority rule or the relative majority in which a given individual, the chairman, can always break ties. An axiomatization of the relative majority rules with a chairman is suggested that holds for an even number of individuals and that, for an odd number of individuals, characterizes the rules that are either the relative majority rule or a relative majority rule with a chairman.     

‘SUBTERRANEAN PASSAGES OF THOUGHT’: EMPIRE'S INSERTS

Scattered throughout Hardt and Negri's Empire are a number of short sections whose manifesto-like energy contrasts with the relatively expository style of the main text. These passages, modeled after the scholie of Spinoza's Ethics, are meant to suggest new ways of thinking about material already presented, to highlight the affective aspect of the material, and to point to hidden connections among different discursive elements. Several of these which did not appear in the published version of Empire for reasons of space are published here for the first time. The matters touched on are as diverse as those in Empire itself: Totality as a philosophical problem, the gender of biopolitical production, the relationship between genocide and the nationstate, the possibility of hope; the paradoxes of unemployment, the function of fear, postmodern prophecy,Hollywood's imperial fantasy, and the paradoxical relationship between being-against and love that has puzzled and fascinated many of Empire's readers.     

Aesthetic Understanding of Work and Organizational Life: Approaches and Research Developments

The aesthetic dimension of work and organizational life attracted the attention of organization scholars during the 1980s and 1990s, and its study burgeoned at the turn of the new millennium. There are today four main approaches to the study of organizational aesthetics: (i) the archaeological approach which privileges the symbolic dimension of aesthetic understanding; (ii) the empathic-logical approach which seeks to grasp the pathos of organizational life; (iii) the aesthetic approach which emphasizes the negotiation of organizational aesthetics; (iv) the artistic approach which examines flow, creativity, and playfulness. They all engage in an intellectual controversy with approaches to the study of organizations which privilege the mental, cognitive, and rational dimension of social action whilst neglecting the material, sensible, and emotional dimension of work relations in organizations. This article will illustrate and discuss these approaches by paying particular attention to the topics of the emancipation of people at work and the style of work and organizational practices.     

Physical consequences of falls in the elderly: a literature review from 1995 to 2010

In the last decade, population ageing has been registered as a global phenomenon. A relation exists between falling and ageing, since falling frequency increases significantly with age. In fact, one in three older adult falls annually. Although ageing is generically associated with decrease and degeneration of psychological and physical functions, it is still not common for the correct identification of risk factors to lead to a clinical prognosis of the elder being in risk of falling. Therefore, the goal of this review article is to identify, categorise and analyse typical ageing and fall factors mentioned in the literature as well as to quantify the number of times they were referenced. The research considered hundreds of publications, but analysis was then restricted to the 87 most pertinent articles written in English and published in journals or scientific magazines between 1995 and 2010. We concluded that falls among older adults can be characterised by the following: anatomic characteristics and physiological consequences of ageing; the pathologies that induce falls, which can be neurological, musculoskeletal, cardiovascular and other diseases; causes and risk factors of falls that can be behavioural, biological, environmental or socio-economic; type of physical consequences of falls, including fractures, bruises, injuries or other physical consequences; and strategies to prevent, mitigate or rehabilitate, which can be of a physical, environmental or behavioural nature.