Estimation in a truncated bivariate poisson distribution using the EM algorithm

An EM algorithm (Dempster et al., 1977) is derived for the estimation of parameters of the truncated bivariate Poisson distribution with zeros rnissing from both margins. The observed inforrnation matrix is obtained and a numerical exarnple is given where the convergence of the EM algorithm is accelerated by the methods of Louis (1982) and conjugate gradients (Jamshidian antl Jennrich, 1993).     

The covariance of the backward and forward recurrence times in a renewal process: the stationary case and asymptotics for the ordinary case

In a Poisson process, it is well-known that the forward and backward recurrence times at a given time point t are independent random variables. In a renewal process, although the joint distribution of these quantities is known (asymptotically), it seems that very few results regarding their covariance function exist. In the present paper, we study this covariance and, in particular, we state both necessary and sufficient conditions for it to be positive, zero or negative in terms of reliability classifications and the coefficient of variation of the underlying inter-renewal and the associated equilibrium distribution. Our results apply either for an ordinary renewal process in the steady state or for a stationary process.     

HUSBAND ABUSE: FACT OR FICTION?

During the last thirty years, ideologies, theories and policies relating to domestic violence have changed radically. As a result of this, community concern and state policies shifted considerably towards protecting and supporting abused wives. Although this shift was justified by the extreme severity of the problem and the relative inadequacy of relevant policies of the past to address wife abuse effectively, it nevertheless led to a partial neglect of other types of domestic violence. Particularly wife-to-husband abuse has been totally ignored and neglected, and even taken to be the fault of the victim. This paper explores the status of husband abuse, by re-assessing relevant trends and developments in Australia and other countries, and presents a review of empirical evidence which shows that husband abuse is more common and more serious than it is generally believed to be, and that it is the task of the government to address spouse abuse by means of policies and practices which are free from a sexist bias.     

Discriminating membrane proteins using the joint distribution of length sums of success and failure runs

Discriminating integral membrane proteins from water-soluble ones, has been over the past decades an important goal for computational molecular biology. A major drawback of methods appeared in the literature, is that most of the authors tried to solve the problem using machine learning techniques. Specifically, most of the proposed methods require an appropriate dataset for training, and consequently the results depend heavily on the suitability of the dataset, itself. Motivated by these facts, in this paper we develop a formal discrimination procedure that is based on appropriate theoretical observations on the sequence of hydrophobic and polar residues along the protein sequence and on the exact distribution of a two dimensional runs-related statistic defined on the same sequence. Specifically, for setting up our discrimination procedure, we study thoroughly the exact distribution of a bivariate random variable, which accumulates the exact lengths of both success and failure runs of at least a specific length in a sequence of Bernoulli trials. To investigate the properties of this bivariate random variable, we use the Markov chain embedding technique. Finally, we apply the new procedure to a well-defined dataset of proteins.     

Real-time monitoring of carbon monoxide using value-at-risk measure and control charting

One of the most important environmental health issues is air pollution, causing the deterioration of the population's quality of life, principally in cities where the urbanization level seems limitless. Among ambient pollutants, carbon monoxide (CO) is well known for its biological toxicity. Many studies report associations between exposure to CO and excess mortality. In this context, the present work provides an advanced modelling scheme for real-time monitoring of pollution data and especially of carbon monoxide pollution in city level. The real-time monitoring is based on an appropriately adjusted multivariate time series model that is used in finance and gives accurate one-step-ahead forecasts. On the output of the time series, we apply an empirical monitoring scheme that is used for the early detection of abnormal increases of CO levels. The proposed methodology is applied in the city of Athens and as the analysis revealed has a valuable performance.     

SEX AND POWER IN SAME-SEX COUPLES

The purpose of this paper is to present a part of the findings of a study of 82 homosexual couples (40 gay and 42 lesbian couples) living in three states and in city and country areas. The respondents were chosen by means of snowball sampling and the methods of data collection were semi-standardised questionnaires and interviews. The paper explores the gender identity of homosexual partners, and the power structure of the homosexual units, and examines the types of sexual relationships maintained by homosexual partners. The paper concludes that homosexual couples are diverse in their sex identity, sexual relationships and power structure, and that although in terms of power they are similar to heterosexual couples they are definitely different from them in their sexual attitudes and behaviour and in the perception of their sexual identity. The paper, finally, underlines some implications for social theory and social policy.     

The Atypical Family: Mode or Necessity?

The study of de facto families has been neglected, despite the fact that they occur all round the world under various names and among individuals of all social strata. This paper analyses these atypical families in terms of their appearing to be stable social systems with consciously selected partners. Thirteen motives of individual and social provenance are found to be involved in their establishment. Although the older families are preponderantly a result of societal stress, modern atypical families in most cases are a mode expression.     

Marital power and quality of marriage

This Workshop was organized recently by the “Christians in Social Work-Social Welfare” group in Sydney and was led by Jim Crawley, a Senior Lecturer in Social Work at Preston Institute of Technology. Although the Workshop was intended primarily for social workers, attendance was open to those working in related spheres of activity. The terms “interpersonal helping” and “counsellor” were used as they are indicative of a type of activity and are not associated with any one professional group.