Random field models in image analysis

Image models are useful in quantitatively specifying natural constraints and general assumptions about the physical world and the imaging process. This review paper explains how Gibbs and Markov random field models provide a unifying theme for many contemporary problems in image analysis. Random field models permit the introduction of spatial context into pixel labeling problems, such as segmentation and restoration. Random field models also describe textured images and lead to algorithms for generating textured images, classifying textures, and segmenting textured images. In spite of some impressive model-based image restoration and texture segmentation results reported in the literature, a number of fundamental issues remain unexplored, such as the specification of MRF models, modeling noise processes, performance evaluation, parameter estimation, the phase transition phenomenon, and the comparative analysis of alternative procedures. The literature of random field models is filled with great promise, but a better mathematical understanding of these issues is needed as well as efficient algorithms for applications. These issues need to be resolved before random field models will be widely accepted as general tools in the image processing community.     

Socio-economic correlates of fecundability in a sample of taiwanese women

Estimates of fecundability (monthly probability of conception) in the absence of contraception are derived from the frequency distribution of conceptive delays immediately following marriage, reported by 2,443 married women aged 20 to 39 included in the Taichung (Taiwan) Intensive Fertility Survey of 1962. Average fecundability of women is positively associated with their socio-economic status. These differentials are not accounted for by differences among socio-economic groups with respect to memory and truncation biases (associated with the marriage duration), wife’s age at marriage, or unreported premarital conceptions. A Multiple Classification Analysis suggests that among the socio-economic characteristics, husband’s education, rural background, and modern family type are the more important predictors of fecundability. The importance of genetic factors as opposed to cultural factors in producing these socio-economic differences in fecundability can not be evaluated systematically. Moreover, the relation of a couple’s privacy, their attitude toward family building, and patterns of mate selection to their socioeconomic status would have to be taken into account before the differences in fecundability could be attributed to factors such as nutrition, health, or infections which might directly influence their physiological ability to conceive.     

Mortality in Ghana: Evidence from the cape coast project data

Abstract This paper deals with the estimation of mortality for a rural community of about 20,000 persons in the rain-forest area of south-west Ghana. Specifically, infant, child and adult mortality estimates have been obtained by the application of a wide range of direct and indirect methods of measuring mortality from the different statistics collected by a longitudinal mortality and fertility project conducted during 1974-7. It was noted that infant and childhood mortality rates obtained from death registrations were consistent with those rates yielded by pregnancy histories and child survival statistics. However, the adult mortality estimates derived from orphanhood statistics tended to be lower than those suggested by death registrations. The analysis revealed an infant mortality rate of 100 for boys and 84 for girls, equal childhood mortality rates for boys and girls (85-6), a lower expectation of life at birth for men (45.8 years) than for women (52.8), and a much more severe incidence of mortality among men aged over 40 than for women at the corresponding ages.     

Net delay of next conception by contraception: A highly simplified case

Abstract A probability model, building on the work of Perrin and Sheps, is presented and applied. The model makes it possible to follow a cohort of women from a pregnancy outcome to next conception. Principal simplifying assumptions are homogeneity among women and constant fecundity. Cases treated include no contraception; a single contraceptive method practised; and a second contraceptive method practised following a first one. Expected durations to next conception may be calculated in relation to the following factors: outcome of previous pregnancy, length of anovulation, natural fecundability, time first contraceptive method is initiated, characteristics of first contraceptive (effectiveness and continuation rate), characteristics of second contraceptive, and gap between termination of first and commencing second contraceptive. By suitably pairing runs of the model, one can construct experiments in which the only differentiating factor is use and non-use of a specified contraceptive, and, by differencing the corresponding mean durations to next conception, compute the net delay of next conception produced by that contraceptive.     

Post-reform India’s automotive-iconic-cement assemblages: uneven globality,territorial spectacle and iconic exhibition value

India’s post-liberalisation landscape has unexpectedly been populated by monumental iconic statues. These statues, co-emergent with an automobile and construction boom and an attendant resignification and revaluing of land, are a productive site for rethinking the role of spectacle in neoliberal globalisation from the locus of post-liberalisation India. Against theories that characterise spectacle as primarily virtual and deterritorialised, they illuminate how spectacle is enmeshed in the imaginaries, spatial politics, material processes and heterogeneous temporalities of uneven development. Their religious aspect also calls for a re-examination of Benjamin’s distinction between cult value and exhibition value.     

Comparison of confidence intervals of traffic intensity forM/E k/1 queueing systems

This paper compares the width of confidence intervals for the traffic intensity inM/E _k/1 queueing systems with three methods-Lilliefors' method, a second method based on the number of arrivals during the service period, and a third method using censored observations, in which only those service periods with no arrivals are observed. It is shown that the width of confidence intervals, based on the number of arrivals during the service period, is narrower than for other methods.     

Demographic aspects of lactation and postpartum amenorrhea

Interrelations between lactation and post-partum amenorrhea are studied from the reports of about 5,000 married women included in a 1966 Follow-up Survey of Acceptors of an Intrauterine Device (IUD) in Taiwan. The length of post-partum amenorrhea and of breastfeeding are positively associated. On an average, breastfeeding delayed the resumption of menstruation by about 7 months. The association between lactation and amenorrhea is not accounted for by differences in mother’s age, parity, education and her place of residence. A multiple regression analysis suggests that (1) age affects amenorrhea both directly and through lactation, (2) parity has no independent effect on either lactation or amenorrhea, and (3) education and place of residence affect amenorrhea mainly through the cultural variations in the practice of breastfeeding.     

Centrality Asymmetry and Partner Complementarity as Influences on Alliance Dissolution

Research on interfirm alliances indicates that partner firms’ asymmetry in network centrality increases the likelihood of alliance dissolution because it gives rise to a power imbalance and opportunism in the partnership. We contend that this view of centrality asymmetry does not consider the binding force that network resource complementarity can provide in an alliance, which motivates partners to ally for the long term. We propose that centrality asymmetry can have both divisive and cohesive forces in an alliance, which – when considered together – lead to a prediction that centrality asymmetry has a U‐shaped relationship with alliance dissolution. Moderate levels of asymmetry lead to lower rates of dissolution than high and low levels of asymmetry. The degree of cooperation between partners and the degree of external competition reduce the effects of centrality asymmetry on alliance dissolution because they mitigate power imbalances while encouraging partners to strengthen the alliance to withstand competitive challenges.     

Analytic evaluation of the expectation and variance of different performance measures of a schedule on a single machine under processing time variability

In this paper, we present closed-form expressions, wherever possible, or devise algorithms otherwise, to determine the expectation and variance of a given schedule on a single machine. We consider a variety of completion time and due date-based objectives. The randomness in the scheduling process is due to variable processing times with known means and variances of jobs and, in some cases, a known underlying processing time distribution. The results that we present in this paper can enable evaluation of a schedule in terms of both the expectation and variance of a performance measure considered, and thereby, aid in obtaining a stable schedule. Additionally, the expressions and algorithms that are presented, can be incorporated in existing scheduling algorithms in order to determine expectation-variance efficient schedules.     

A test for bivariate exponentiality against bifr alternative

A test is proposed for testing bivariate exponentiality against the Bivariate Increasing Failure Rate (BIFR) class of alternatives. The test statistic is a function of U-statistics and hence asymptotically normally distributed and consistent